Caratterizzazione mineralogica e chimica delle ceneri pesanti provenienti dalla combustione dei rifiuti

UNIVERSITÀ DI PARMA Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale Corso di Dottorato in Scienze della Terra Ciclo XXXV (2019 – 2022) MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF BOTTOM ASHES FROM WASTE INCINERATION Caratterizzazione Chimica e Mineralogica delle ceneri pesanti provenienti dalla combustione dei rifiuti Tutor: Prof. Mario Tribaudino Prof.ssa Luciana Mantovani Coordinatore: Prof. Marco Roveri Candidata: Dott.ssa Chiara De Matteis Department of Chemistry, Life Sciences and Environmental Sustainability Ph. D in Earth Sciences XXXV cycle (2019 – 2022) MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF BOTTOM ASHES FROM WASTE INCINERATION Supervisors: Prof. Mario Tribaudino Prof.ssa Luciana Mantovani Coordinator: Prof. Marco Roveri Candidate: Dott.ssa Chiara De Matteis Table of contents PREFACE ....................................................................................................................................... 1 1 INTRODUCTION......................................................................................................................... 4 1.1 AGE OF HUMANS ........................................................................................................... 4 1.2 GLOBAL WASTE PRODUCTION .................................................................................... 5 1.3 EUROPEAN AND ITALIAN WASTE MANAGEMENT .................................................... 6 1.4 WASTE TO ENERGY PLANTS ........................................................................................... 10 1.5 BOTTOM ASHES: COMPOSITION AND PROBLEMS ....................................................... 13 1.5.1 Physical characterization ................................................................................................. 14 1.5.2 Chemical and mineralogical characterization .................................................................... 14 1.5.3 Recovery and recycle of Bottom Ashes ............................................................................... 20 1.5.4 Mineralogy, PTE elements and environmental concern: aims of this thesis .......................... 23 2. MATERIALS AND METHODS ................................................................................................. 25 2.1 DESCRIPTION OF THE WASTE-TO-ENERGY PLANT ..................................................... 25 2.1.1 Parma WtE plant (Iren group) .......................................................................................... 25 1.6.2 Piacenza WtE plant (Iren group) ....................................................................................... 25 1.6.3 Torino WtE plant (Iren group) .......................................................................................... 25 1.6.4 Ferrara WtE plant (Hera group) ....................................................................................... 25 1.6.5 Forlì-Cesena WtE plant (Hera group) ............................................................................... 26 2.2 SAMPLING.......................................................................................................................... 26 2.3 SAMPLE PREPARATION ................................................................................................... 26 2.4 GRAIN SIZE ANALYSIS ..................................................................................................... 26 2.5 THERMO GRAVIMETRIC ANALYSIS (TGA) .................................................................... 26 2.6 SEM-EDS OBSERVATIONS AND ANALYSIS ..................................................................... 27 2.7 X-RAY POWDER DIFFRACTION (XRPD) ANALYSIS ....................................................... 28 2.8 X-RAY FLUORESCENCE (XRF) ANALYSIS ...................................................................... 29 2.8.1 XRF spectroscopy: conventional source ............................................................................. 29 2.8.2 µ - XRF spectroscopy: synchrotron radiation ..................................................................... 30 2.9 X-RAY ABSORPTION SPECTROSCOPY (XAS) ................................................................. 31 2.10 LEACHING TEST .............................................................................................................. 34 2.11 SEQUENTIAL EXTRACTION PROCEDURE (SEP) .......................................................... 35 2.12 ATOMIC ABSORPTION SPECTROSCOPY (AAS) ANALYSIS ......................................... 38 2.13 IONIC CHROMATOGRAPH (IC) ANALYSIS ................................................................... 38 2.14 INDUCTIVELY COUPLED PLASMA – MASS SPECTROMETRY (ICP-MS) ANALYSIS . 38 2 2.15 STATISTICAL ANALYSIS ................................................................................................ 39 3 RESULTS AND DISCUSSION .................................................................................................... 40 3.1 MINERALOGICAL CHARACTERIZATION OF BOTTOM ASHES ................................... 40 3.1.1 Particle size and Potential Toxic Elements speciation in Municipal Solid Waste Incineration (MSWI) Bottom Ash ................................................................................................................ 40 3.2 COMPARISON BETWEEN WtE PLANTS IN NORTHERN ITALY..................................... 59 3.2.1 Grain size and mineralogical constrains on leaching in the bottom ashes from municipal solid waste incineration: a comparison on 5 plants from Northern Italy ............................................... 59 3.3 PTE SPECIATION: COMBINED SEM-EDS ANALYSIS, XRF AND XANES BY SYNCHROTRON RADION STUDY .......................................................................................... 81 3.3.1 PTE speciation in Bottom Ashes from Municipal Solid Waste Incinerator: a combined SEMEDS, XRF and XANES by synchrotron radiation study .............................................................. 81 3.4 SEQUENTIAL EXTRACTION PROCEDURE AND ENVIRONMENTAL CONCERN ....... 106 4 CONCLUSIONS ....................................................................................................................... 112 REFERENCES ............................................................................................................................ 115 WEB REFERENCES ................................................................................................................... 127 APPENDIX I .............................................................................................................................. 128 APPENDIX II.............................................................................................................................. 132 APPENDIX III ............................................................................................................................ 133 APPENDIX IV ............................................................................................................................ 134 APPENDIX V .............................................................................................................................. 136 APPENDIX VI ............................................................................................................................ 138 APPENDIX VII ........................................................................................................................... 139 APPENDIX VIII .......................................................................................................................... 144 APPENDIX IX ............................................................................................................................ 149 APPENDIX X .............................................................................................................................. 154 APPENDIX XI ............................................................................................................................ 159 APPENDIX XII ........................................................................................................................... 160 APPENDIX XIII .......................................................................................................................... 161 APPENDIX XIV .......................................................................................................................... 162 APPENDIX XV ........................................................................................................................... 163 APPENDIX XVII ........................................................................................................................ 165 1 PREFACE Waste generation is, today, a hot topic, strongly linked to environmental problems. Wastes have been produced since the dawn of civilization: the increasing world population and global development occur together with an increasing production of man-made objects, which at the end of their life become waste. Increasing industrial production in the last two centuries pose the problem of their disposal, and in more recent times of their management. Waste management is nowadays a global topic together with that of climatic changes and georesource shortage: it is foreseen to become more and more critical in response to the improvement in life standard in developing countries and in the increased consumption of raw materials. Waste management is a complex issue, aiming to reduce the production and to recycle and reuse the waste, avoiding or minimising any dispersion in the environment. The goal in waste management can be summarised in the mantra “from waste to resource”. Prominent among improvements and innovations concerning waste management are Waste-toEnergy (WtE) plants, systems that generate energy from the combustion of solid waste, mostly municipal. In WTE plants the solid waste is burned, with a positive energy balance, coming from the combustion of the wastes, which is used for the energy production. However, like any anthropogenic activity, this process generates wastes: Bottom Ashes and Fly Ashes. BA are the residual ashes in the bottom part of the combustion chamber, whereas FA are the residuals blowing out from the chamber. Also, BA from Municipal Solid Waste Incinerator (MSWI) can be recycled. Due to their physical and chemical-mineralogical characteristics, BA can be used as a secondary source of raw material or recycled into construction and cementitious materials. However, their recycling may be compromised due to the presence of Potential Toxic Elements (PTE), i.e. chromium, lead, and zinc, as their release may be harmful to the environment and human health. The aim of this thesis is to provide a systematic and in-depth study on the BA, with special focus on the medium-fine fraction (< 4mm). This work has two goals, the mineralogical characterization of the BA and the assessment of their potential release. In both, special attention was paid to PTE. The goals are closely related, as the information on the mineralogical phases hosting the PTE is a key point for interpreting and assessing the potential release of the BA in the environment. In this work BA from 5 WtE plants in Northern Italy were sampled and sorted by grain size. Each sampling was analysed by Thermo Gravimetric Analysis (TGA), X-Ray Powder Diffraction (XRPD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM - EDS) and X-ray Absorption. Synchrotron based Near Edge Spectroscopy (XANES) analyses were further conducted, to obtain a full chemical and mineralogical information. 2 The potential release of BA was investigated on particle sizes < 4mm by leaching test and sequential extraction procedure. From the results obtained, we found that several elements exceed the legal limits (chlorides, copper) already in the leaching test, where extraction is conducted only with ultrapure water at neutral pH. The relation between grain size, composition, and leaching potential were assessed in the ashes to discuss the potential of grain size sorting in high value applications of them. This thesis is organised as follows. In the first chapter the concept of waste is introduced, together with the figures on global and national waste production. The operational procedures and different types of waste-to-energy plants are described, and the characterization of BA is introduced. A literature review on the current state of the art on chemical, physical and mineralogical characteristics, together with the possible environmental problems and reuses of the BA is addressed. In the second chapter the materials and methods used in this work are outlined, in what they are common to this investigation. Specific aspects are further discussed in the sub-chapters 3.1, 3.2, 3.3 and 3.4. The chapter 3 shows the results and discussion of the different topics addressed in this investigation. It is divided in four subchapters, each corresponding to a paper published, submitted, or in preparation. In the subchapter 3.1 the paper “Particle size and Potential Toxic Element speciation in Municipal Solid Waste Incinerator (MSWI) Bottom Ash”, published in 2021 in the journal Sustainability, is reported, giving a mineralogical characterization of the BA, with different grain size, from the Parma WtE plant. In the sub-chapter 3.2 the version submitted to the journal Frontiers of the paper “Toward a deep characterization of bottom ashes from municipal solid waste incineration: new data from 5 plants of Northern Italy” is reported. The BA from the WtE plants of Parma, Piacenza, Torino, Forlì-Cesena and Ferrara were examined. The mineralogy, geochemistry and leaching behaviour of the ashes were compared, and the trend outlined in the sub-chapter 3.1 were discussed in their generalization. In the sub-chapter 3.3 the version submitted to the journal Science of Total Environment of the paper “Potential Toxic Elements speciation in Bottom Ashes from Municipal Solid Waste Incinerator: a combined SEM-EDS, XRF and XANES study”, is reported. This investigation discusses the mineralogy of the PTE, combining a SEM-EDS information on the mineralogy of the host phases, with synchrotron based µ-XRF and XANES data, to outline the local distribution and mineralogy of the PTE at concentrations of the order of few ppm. In the sub-chapter 3.4 the results of a sequential extraction procedure on the BA from Parma and Piacenza are reported, and discussed together with a correlation between elements and grain size in the bulk material and in the leached products. A new protocol for the sequential extraction procedure in BA is proposed. 3 Finally, the fourth chapter reports the general conclusions from this work with a final focus on problems in the recycle of the BA. 4 1 INTRODUCTION 1.1 AGE OF HUMANS Humanity is now a dominant geological actor, as human activities induce great, multiple and irreversible changes on Earth. The study of these human-associated changes led to the suggestion that we should not refer to the present time as pertaining to the Holocene epoch but to a new geological epoch called the “Anthropocene” (Crutzen, 2002; Steffen, 2021; Trischler, 2016; Zalasiewicz et al., 2011). In 2000, the first to propose the idea of the Anthropocene were the atmospheric chemist Paul Jozef Crutzen and the limnologist Eugene Filmore Stoermer; since then, the geological community has begun to take an increasing interest in this issue, analysing scientific evidence leading to a definition of the Anthropocene and establishing the “Anthropocene Working Group” (Trischler, 2016). Other scientific branches (biology, ecology, ethology) also began to study the correlation between environmental changes and human activities and the idea of Anthropocene is now accepted and shared by most of the scientific community. However, the scientific debate is still open on establishing the “starting point” of this new epoch. Figure 1.1.1 Comparison of the current Geologic Time Scale with two alternatives. (Lewis & Maslin, 2015) For example, in Figure 1.1.1 the current Geological Time Scale 2012 (a) is compared with two possible scenarios. In the first alternative (b) the Anthropocene Epoch directly follows the Holocene 11 • fumes expulsion: the fumes are channelled into a chimney and expelled into the atmosphere at a temperature of about 120 °C; • ash collection: the ashes obtained from the combustion of waste and the solid particles obtained from flue gas purification are collected in two separate lines, stored and sent to landfills or recycling companies. The most variable part of waste-to-energy plants is the furnace. Three technologies are used (Figure 1.4.2): • Grate furnace technology: this technique is most commonly used. The waste enters through the fuel chute and then it is pushed onto the grate by a feed mechanism. The fuel then moves along the (usually) sloping grate. The upper fuel surface-layer is exposed to radiation from the refractory structures of the furnace and the flames, formed by the volatile gases above the fuel layer, and heats up and dries. Subsequently, as the temperature of the fuel layer rises, the fuel devolatilises as it moves forwards on the grate. When the ignition temperature is reached, combustion starts, promoted by the primary air from the bottom sections: little air is supplied in the drying section, and the remaining primary air is adjusted in the various supply ducts beneath the grate according to the progress of combustion in the central section of the bed. The combustion front formed moves downwards into the bed against the air flow, while the bed moves forwards (Leckner, 2015). The combustion temperature is between 750 and 1000°C. • Fluised bed technology: in contrast to the fuel bed on the grate, the fuel is introduced to an inert fluidized bed, consisting of sand-like particles of about 0.5 mm in size, and mixes with this bed material and the remaining ashes from the waste. The advantage of the fluidized bed is the hot bed, which has a great thermal inertia for the fuel particles to burn in a controlled and thermally stable environment. This advantage is not entirely effective in waste combustion, though, because the volatile part of the fuels tends to burn in the freeboard above the bed in any case. The bed temperature is usually 850° C, but it could be higher as long as the bed does not sinter. The primary fluidization air is introduced through nozzles, traditionally covering the entire bottom of the furnace, the ‘‘distributor plate’’. This leads to accumulation of larger and denser objects in the bottom region, originating from the waste, which eventually prevents proper air distribution, disturbs fluidization, and favours agglomeration. Therefore, fluidized bed combustion of waste has the reputation of requiring well sorted waste (Leckner B., 2015). • Rotating furnace technology: the rotary furnace, or rotary kiln, is used for drying and other operations involving granular materials. In the field of waste treatment, it is most frequently 12 employed for combustion of hazardous waste. A rotary furnace consists of a cylindrical steel vessel, of 10 m in length and a few metres diameter, inclined by a few degrees from the horizontal plane. Inside, the vessel is protected by refractories. The cylindrical steel vessel rests upon rolls and is rotated at a speed between 0.05 and 2 revolutions per minute. The fuel is fed at one end and the ashes leave at the other end. Drying, devolatilization, and combustion take place, while the fuel is rotated and mixed, sometimes even enhanced by internals. The length and diameter of the cylinder, as well as its rotation speed, slope, and internals, all influence the residence time of the fuel particles. This ability to control the residence time even in wastes of different input is the main advantage of the device. However, the incineration often does not come to completion and usually an afterburner combustion chamber is needed (Leckner B., 2015). Figure 1.4.2 The most common conversion device for waste, here shown in the form of combustors: (a) grate furnace, (b) fluized bed and (c) directly heated rotary furnace (Leckner B., 2015) After an initial cooling phase, bottom ashes are screened manually or mechanically to remove oversized unburned residues. In addition, the ferrous metal fraction is removed with overhead magnetic separators and the non-ferrous metal fraction is removed by Eddy current. Subsequently, the material is stored on site awaiting aging. As mentioned above, from the combustion of waste not only energy is obtained but also residual ashes. The ashes, which are also a waste, can be classified on the basis of its size and hazardousness: • Fly Ashes (FA): their mass represents 2% -5% of the incinerated waste. The FA are the solid particles that are released with the combustion fumes and are removed after the purification process. Due to the high concentration of PTE, the FA are classified as hazardous waste (EWC 13 code 19.01.13 *: fly ash containing hazardous substances) and for this reason they cannot be recycled without pre-treatment and are usually collected and stored in specific landfills (Zhu J. et al., 2020; Qiu et al., 2017; D.Lgs 152/06). • Bottom Ashes (BA): BA are one of the major by-products obtained during municipal solid waste incineration in waste-to-energy plants; their mass is 20% of the incinerated waste. Once the incineration process is complete, the BA are thrown into a tank full of water for rapid cooling. The BA are classified as non-hazardous waste (EWC code 19.01.12: bottom ash and slag other than those in 19.01.11 *). 1.5 BOTTOM ASHES: COMPOSITION AND PROBLEMS The BA are made up of different fractions which, thanks to the non-hazardous nature of the unburned material, can be recycled becoming a resource. The fractions can be divided as: • glass (soda-lime glass), coming from domestic items such as bottles and glasses. The amount of glass is highly dependent on the presence of a selective collection of urban waste. • Synthetic ceramics, derived from clay-based materials (e.g. tiles and bricks), porcelain and concrete. • Paramagnetic metals, which represent a 2-5 wt%; usually they originate from steel and iron pieces oxidised in the incineration furnace. Mineral phases such as magnetite (Fe3O4), hematite (Fe2O3) and wuestite (FeO) are characteristic of the BA fine fraction that is not removed by the magnetic separator. • Minerals, such as feldspars calcite and quartz may have a natural origin (they are common in soil and rock), but they are also common components in ceramics or building materials as well as major weathering products in MSWI BA (calcite). • Diamagnetic metals, which represent 10-12 wt% of the BA weight. They are mainly represented by aluminium and copper, and tend to be concentrated in the finest fraction (below 1 mm). • Unburned organic matter which comes from the partial combustion of food residues, paper, fabric and bone fragments (Chimenos et al., 1999). The composition of BA varies over time and from country to country, due to the differences in lifestyle and waste recycling processes of a country. To note, it is extremely heterogeneous and may change, also in the same plant, depending on the different mix of wastes burned each day; moreover, even within the same mix, there are seasonal differences (Dhir et al., 2017). This heterogeneity in the waste incoming material gives rise to a variation in compositions from grain to grain in the BA. Moreover, some inhomogeneity in the combustion temperature adds further heterogeneity in the 14 thermodynamic conditions of local equilibria. It must be emphasised that, despite this heterogeneity, some phases are commonly found (Chimenos et al., 1999; Forteza et al., 2004; Inkaew et al., 2016; Lynn et al., 2016; John Chandler et al., 1997c; Alam et al., 2019; Tyrer, 2013; Lam et al., 2010; Caviglia et al. 2019; Mantovani et al. 2021). This complex chemical and mineralogical composition gives rise to numerous scientific questions regarding their reuse and non-hazardousness. Over the past 20 years, many research groups studied BA by implementing a multidisciplinary approach merging the contributions of environmental geology, geochemistry, and engineering. The properties of the BA can be divided into chemical and physical properties. These properties are essential for a management of the waste: any proposed recycle must take into account the chemical and physical reactivity of the ashes, to optimise the industrial production, to assess and improve the performance of the recycled product, and to predict its long-term use in terms of pollution and durability. 1.5.1 Physical characterization The mineral fraction of BA is typically light to dark grey and is a granular material (although it may also contain large fused lumps). The physical characterization of the BA involves, preliminary to other investigations, an analysis of the grain size distribution. The grain size distribution is most important in the recycling in the construction industry, and, as discussed in the following, may be different in different incinerators. The particle size distribution is typical of well-graded materials and generally conforms with that of sandy gravel, with a content of 40mm oversize particles commonly below 5% by total mass as well as a low portion of fines (<63 micron) (Astrup et al 2016, Izquiero et al. 2011). Broadly speaking we have that about 45 % of the mass of the BA is made by grains larger than 5 mm, whereas about 35 % of the mass falls in an intermediate grain size between 1 and 5 mm; fine-grained material between 0.1 and 1 mm make about 10 % in weight, whereas the remaining 10 % of the BA shows a grain size less than 0.1 mm (Dou X. et al., 2017; Šyc et al., 2018Huber et al., 2020). Other physical properties that can describe BA are represented by the loss of ignition, usually 1-3% (Lynn et al., 2017) i.e. weight percentage lost when heated for 4 h at 500 °C, specific gravity, bulk density (t/m3) that is typically 1.200-1.800 kg/m3, and water absorption (%). 1.5.2 Chemical and mineralogical characterization The composition of the BA changes with the input material, the combustion technology, and the post combustion weathering. The input material depends on local lifestyle waste production, but also by 15 selective collection of household waste. Selective collection makes it possible to recover materials for which recycling options are available and economically viable. It was observed that, where separate collections were carried out, glass and paper/cardboard fraction sent to incineration fell by 10% and 8% respectively, while the proportion of other materials (e.g. textiles) increased by 30%. A lower silicon content in the of BA was found after the introduction of selective collection, which decreased the input in bottle glass to the incinerator (del Valle-Zermeno et al., 2017). The composition of the ashes changes also as a function of the incineration technology: incineration is a complex technique to master because it involves several essential parameters as the storage and composition of incoming waste, the feeding to the furnace, the combustion temperature, the ignitability of the wastes, the oxygen supply and the process time in the furnace. These parameters have important effects in the mineralogical composition of the ashes and in the presence of organic matter. The same input material, burned with different furnace technologies, rotating, fluidized bed or grate, will produce a different mineralogical composition of the ashes. As mentioned before, the grate furnace is the most used in household waste incineration plants. Also, the cooling after incineration affects the mineralogical composition of the ashes. The cooling can be with water or air. The water-cooling process is the most used and produces a rapid cooling together with chemical reactions between BA and water, loss of metals due to oxidation or adhesion of mineral matter to metals. Air cooling generates dust that requires special treatment but avoids the chemical interaction with water. The maturation processes can reduce the environmental pollution potential of the material, as thermodynamically unstable compounds evolve into more stable secondary compounds in the presence of carbon dioxide, but also of oxygen or water. Usually BA are exposed to air for 1 to 12 months. Maturation changes the chemical and mineralogical composition, absorbing CO2 to form carbonates, mostly calcite, and moisture vapour, to form cement minerals like ettringite. For all these factors the ashes are very heterogeneous even from the same incineration plant. However, despite these variables, there are similarities among the different chemical compositions reported in the literature (Table 1.5.2.1). Generally speaking, the major oxides in BA are CaO, SiO2, Al2O3 and Fe2O3 that represent between 60 and 80 wt% of the chemical composition. The minor elements are Cu, Zn, Cr, Sb, Mo, Co and Ni, and make up about 1.5–2.0 wt% along with 1.5–5.0 wt% of chlorides and sulfates, the actual amount depending also on the size fraction of BA (Alam et al. 2020). For each element systematic differences are observed as a function of the grain size (Caviglia et al., 2019; del Valle-Zermeno et al., 2017; Loginova et al., 2019; Huber et al., 2019). Among the major elements, (Si, Ca, Al, and Fe) Si content 16 increases with grain size, while Ca follows an opposite trend. Al, Fe, Mg and K show definite trend as reported in (Caviglia et al., 2019; Funari et al., 2015; Loginova et al., 2019). For minor and trace elements, on the other hand, greater variability has been reported but in the last literature data published the higher concentrations are found in the finer fraction (Caviglia et al., 2019; Funari et al., 2015; Loginova et al. 2019). The point will be discussed in the following in more detail. These elements combine together to form crystalline and amorphous silico-aluminates. In fact, BA are characterised by refractory (ceramic, metals unaffected by the combustion process) and melt (slag minerals formed during incineration) phases. Quenched BA are formed by agglomerated material, containing carbonates and hydrated phases (Inkaew et al., 2016). Usually, glass/amorphous phases form the particle core, while on the particle surface hydration products are found as calcium silicate hydrates (C-S-H), Friedel’s salt/hydrocalumite, ettringite, gypsum and calcite. The cooling inside the tank can be a source of chlorides and sulphates due to the presence of Cland SO42in the quenching water (Ito et al., 2008). In general, glass and semi-fused metallic material is present in larger amounts in the coarser particle sizes, while slags are present in greater amounts in the finer grain size classes. The most common mineralogical phases are (i) silicates (quartz, melilites, feldspars), (ii) carbonates (calcite, vaterite), (iii) oxides (magnetite, hematite, corundum), and (iiii) hydrated phases typical of cementitious materials (hydrocalumite, portlandite, ettringite, stratlingite). For further details see Table 1.5.2.2, from Syc et al. (2020). In addition to these main phases, a high content of amorphous material is also present (Alam et al., 2019; Bertolini et al., 2004; Bayuseno & Schmahl, 2010; Caviglia et al., 2019; Yao et al., 2012). Mineralogical composition also varies as a function of grain size: for example, the amorphous content is higher in larger grains while carbonates are present in greater amounts in the finer grains. 17 Major Elements Concentration range (min-max) in mg/kg Potential toxic elements Concentration range (min-max) in mg/kg Rare earth elements Concentration range (min-max) in mg/kg Platinum metal group Concentration range (min-max) in mg/kg other precious and critical elements Concentration range (min-max) in mg/kg Al 14000 – 79000 Ba 69 – 5700 Sc 1.3 – 22 Pt 0.074 – 0.53 Ag 0.2 – 36.9 Ca 8600 – 170000 Cd 0.3 – 70 La 2 – 30 Pd 0.03 – 1.8 Au 0.1 – 2.2 Fe 3100 – 150000 Cu 190 – 25000 Ce 11 – 51 Ir 0.0007 – 0.007 Sb 7.6 – 430 K 660 – 16000 Cr 20 – 3400 Pr 1.1 – 10 Rh < 0.030 Be 1.2 – 6 Mg 240 – 26000 Mo 2.5 – 280 Nd 4 – 37 Ru < 0.01 Co 6 – 350 Mn 77 – 3200 Ni 7.0 – 4300 Sm 0.93 – 5 Ga 7 – 24 Na 2200 – 42000 Pb 75 – 14000 Eu 0.25 – 2.6 Ge 0.78 – 2.7 P 440 – 10500 Se 0.05 – 10 Gd 0.88 – 5 In < 1.7 Si 4300 – 308000 Sn 2 – 470 Tb 0.18 – 3 Nb 2 – 14 Ti 2783 – 7479* Tl 0.0077 – 0.23 Gy 0.54 – 3 Ta 2.5 – 14 Cl 3644 – 37633 V 16 – 120 Ho 0.11 – 0.45 W 10 – 320 S 1310 – 16808 Zn 10 – 20000 Er 0.31 – 2 Li 2 – 29* Tm 0.01 – 0.18 Yb 0.31 – 5 Lu 0.02 – 0.23 Table 1.5.2.1: some literature data on the chemical composition of BA (modified from Astrup et al. 2016 and Hjelmar et al. 2013) 18 Mineral phase Chemical formula Unquenced BA Quenced BA Weatered BA quartz SiO2 h, i b, e, f, g, i a, c, d, e, f cristobalite SiO2 g a, g gehlenite Ca2Al2SiO7 h, i b, e, f, g, i a, e, f, g akermanite Ca2MgSi2O7 b, e a, e alkali feldspars (K,Na)(Al,Si)3O8 b, c (albite),g g plagioclase feldspars NaAlSi3O8-CaAl2Si2O8 e, i b, e, i e calcium pyroxene Ca(Mg,Fe)Si2O6 b, g g wollastonite CaSiO3 b, f, g f, g lime CaO e, i b portlandite Ca(OH)2 c, g magnetite Fe3O4 e e, f, g a, e, f, g hematite Fe2O3 h, i i, f, g d, f, g wüstite FeO f, g f, g calcite CaCO3 h, i e, i, f, g a, c, d, e, f, g goethite FeO(OH) d corundum Al2O3 e e gibbsite Al(OH)3 d anhydrite CaSO4 c, e, g d, g gypsum CaSO4 · 2H2O a, g hydrocalumite Ca2Al(OH)6Cl1-x(OH)x 3H2O f, i e friedel’s salt Ca2Al(OH)6Cl · 2H2O i ettringite Ca6Al2(SO4)3 (OH)12 · 26H2O a, c, d, e Table 1.5.2.2 most common mineralogical phases identified in BA. References: a) (Zevenbergen et al., 1998); b) (Eusden et al., 1999); c) (Chimenos et al., 2003); d) (Piantone et al.. 2004); e) (Bayuseno and Schmahl. 2010); f) (Wei et al., 2011); g) (Santos et al., 2013); h) (Bourtsalas. 2015); i) (Inkaew et al., 2016). The negative correlation that exists between grain size and carbonates, but also between grain size and hydrated phases, can be explained through a greater reactivity of the finer grains to the weathering process, as carbonates and hydrated phases are a product of hydration. We may compare the chemical composition of the average continental crust and that of bottom ashes from municipal solid waste incinerators (MSWI), much information on the human activity products can be obtained. Figure 1.5.2.1(a) represents the average composition of the oxides of common element (more an 1wt%) in MSWI BA (from Djikstra et al. (2019), Hjelmar et al. 2013 and this work) vs he composition of the 19 average continental crust (from CRC Handbook 2016). In Figure 1.5.2.1 (a) is clearly visible that most abundant elements in BA (Al, Fe, Si, Ti, K and Na) are very close to that of the continental crust. Only two elements show strong enrichment in BA, Ca and P; also loss on ignition (LOI) content in BA is higher respect to the average crust. Despite the case of Ca and P, the average composition confirms that mineral wastes homogenise the products of industrial activity to obtain something close in composition to the natural continental crust. Figure 1.5.2.1 Average composition of major (a) and minor (b) elements in BA (from Dijkstra et al., (2019), Hjelmar et al. 2013 and this work) vs continental crust composition (from CRC Handbook 2016). Figure 1.5.2.1(b) reports minor elements averaged in the MSWI BA respect to the continental crust. A first group of elements, among which Co, Zr, Li, Hf, Ti, Rb, F, V, Mn, Sr, Ga, U, Th shows an average composition in BA very close to the earth continental crust while a second group made by Cl, Zn, Cu, S, Pb, Br, Mo and Sn, show a significant enrichment in BA, between one and two orders of magnitude. By some respect the chemical processes recorded BA could be similar to those in high temperature geochemistry. The overall composition is not far from that of the global earth, and the temperatures are in the range of the geological high temperature processes; a combustion chamber can be compared with natural high temperature systems. The difference lies in the extreme heterogeneity of the input material. During the incineration we observe in different grains multiple equilibria due to local compositional and temperature heterogeneities. At the local grain size scale the high temperature reactions can be interpreted as indicating the achievement or at least the progress to a thermodynamic 20 equilibrium, obeying to the Gibbs phase rule, whereas at the bulk scale this obviously does not occur. The multiphase, multiple equilibria lead to wealth of phases even in the grains where the high temperature glass and crystals are best preserved. Moreover, unreacted refractory material and low temperature weathering induce further mineralogical complexity. 1.5.3 Recovery and recycle of Bottom Ashes In order to improve the properties of MSWI BA physically or chemically, to obtain a better material for application or to reduce the leaching concentration of contaminants from MSWI BA and lower its environmental risk potential, several treatments have been proposed. Today most plants are equipped with magnetic separators and non-ferrous separators for the recycling of pure metals such as iron or aluminium. From an economic point of view, the recycling of metals provides a financial benefit for the company in addition to obtaining a cleaner stony material. Some authors (Biganzoli & Grosso, 2013; Biganzoli et al., 2012) reported that the recovery level of metals is limited by their particle size. A focal point debated in the last years regards the extraction and immobilisation of contaminants as salts or heavy metals, and their extraction with water or chemical washing. However, it was not recommended to wash the MSWI BA due to the large amount of generated waste water or chemical reagents (Lin et al., 2011; Yang et al., 2012). Generally, the treatments on BA MSWI are matched with their applications, such as using bottom as in concrete and meanwhile, the binders in the concrete have an immobilisation effect on the heavy metals in the BA. The polluting potential of BA is a key factor in deciding on its use as well as its storage in appropriate sites. Actually, each country has defined a regulatory and legislative framework on the management of BA with a view to identify recoverable and non-recoverable materials. The construction sector remains, for all European countries, the main re-use of BA, in order to limit the use of non-renewable natural resources. Unfortunately, the non-uniformity of Country standards act as an obstacle in the full valorisation of these materials. The EU legislation can be found in Directive 2010/75/EU on industrial emissions but each country has its national regulations implementation. Briefly, any waste incineration plant operated in a member state needs to adhere to the minimum requirements set out in the above mentioned directive in which the principal requires are to minimise the amount and potential hazard of combustion residues, and to have recycling strategies in place, after having assessed BA physical and chemical properties, as well as their polluting potential, including the determination of the total soluble fraction and soluble fraction of heavy metals. The European Union requires Member States to carry out leaching tests according to the standards EN 12457/1 2002, EN 12457/2 2002, EN 12457/3 2002, and EN 12457/4 2002, with a liquid-to-solid (L/S) ratio ranging from 2 to 10 l/kg. If the BA respects these statements within the Community of 27 a quantity of material equal to 3 -5mg was sufficient to perform the analysis. TGA were conducted by means of a Perkin Elmer 8000 instrument equipped with a Pt-crucible at a heating rate of 10 °C/min in the temperature range 35°C – 800 °C. All the measurements were run under a constant flux of dry air atmosphere (30 mL/min). 2.6 SEM-EDS OBSERVATIONS AND ANALYSIS In a preliminary step, several BA granules chosen in the Parma WtE plant chosen in the grain size between 8 and 16 mm, to be investigated in the particle size characterization paper, and between 0.5 and 1 mm to be investigated for the paper focussed on XRF-XANES mineral characterization. The grains were embedded in epoxy resin stabs, cut longitudinally. After a preliminary optical observation, by a polarised stereomicroscope BX51, OLYMPUS, Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Spectroscopy (EDX) analysis was done. Scanning Electron microscopy was used to determine the microscopic structure and composition of the phases which are present in the BA. The electron microscopy exploits the interactions that occur between an incident electron beam and the atoms in the sample by returning morphological and chemical information (Figure 2.6.1). Figure 2.6.1 Scheme of electron-matter interactions arising from the impact of an electron beam onto a sample (www.rjl-microanalytic.de/en/) The analyses were done using the SEM image obtained from backscattered electrons, together with EDS point or map analysis. A comparison with optic microscope images was done to highlight the correspondence between compositional and optical inhomogeneities, from the images obtained by backscattered electrons and SEM – EDS mapping. 28 The SEM – EDS analyses were performed at: • Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale (Università di Parma) by a Scanning Electron Microscope coupled with Energy Dispersive System (SEMEDS) JSM IT300LV Jeol 6400 equipped with an Oxford EDX microprobe. Microprobe analysis was performed with operating conditions 20 or 25 kV and 1.2 mA current, ~1µm beam diameter and 75 s counting time; • Dipartimento di Scienze della Terra (Università di Torino) by a JEOL JSM-IT 300LV Scanning Electron Microscope, equipped with Oxford INCA Energy 200 EDS SATW detector (WD 10, KV 15), at 15 kV, 1.2 mA current and 1µm beam diameter. All data collected were processed using the AZTEC software (Oxford instruments, 2006) 2.7 X-RAY POWDER DIFFRACTION (XRPD) ANALYSIS X – Ray Powder Diffraction was used for the identification and quantification of the phases in the samples. It was done on all grain sizes, before further analyses and treatments. The phase determination was done via powder diffraction, using the DIFFRAC.EVA software, whereas the quantitative assessment was done by Rietveld analysis of the diffraction patterns and the GSAS – II package. The samples were ground in an agate mortar in order to obtain a homogeneous powder (< 0.063mm). A 10% by weight standard (Al2O3 or Si) was also placed in each sample to perform quantitative analyses at a later time to assess the degree of crystallinity of the sample and the amount relative to each identified mineralogical phase. The measurements were conducted at: • Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale (Università di Parma) using a Bragg-Brentano Bruker 2D Phaser Diffractometer, with θ – θ geometry, Cu Kα radiation, 30 kV and 10mA and a solid-state detector; • Dipartimento di Scienze della Terra (Università di Torino) using a Bragg-Brentano Rigaku Miniflex 600 Diffractometer, with θ – 2θ geometry, Cu Kα radiation, 40 kV - 15 mA, multistrip detector (128 strip) and Kβ filter on incident beam; The diffraction patterns collected were identified using the Bruker software DIFFRAC.EVA and the Crystallography Open (COD) and PDF-2005 databases. The identification was based on the fit with position and intensity of the main diffraction peaks. Problems in identification of phases with lower concentration came from the complexity of the diffraction patterns, due to the number of mineralogical phases in the BA, and the consequent peak overlapping. Moreover, the intensity of the diffraction pattern was greatly reduced by the presence of glass and amorphous unburned organics. 29 A further bias was that the position and intensity of the main diffraction peaks, in phases showing solid solutions like plagioclase and melilite, was shifted from those in the reference database. By this respect, we can consider fully identified only phases with more than 1-2 wt% presence in the sample. Quantitative analysis was done by means of the Rietveld method. The Rietveld refinement performs the analysis of the measured diffraction profile by modelling the crystal structure, unit cell and relative abundance of the crystalline phases identified in the diffraction pattern. The background, scale factor and sample related peak broadening are modelled as well, whereas instrumental parameters, like wavelength, zero position, and instrumental peak shape are defined by an instrumental file, but can also modelled if necessary (Rietveld, 1967 and 1969; Bish & Post, 1989). The quantitative analysis of the different crystalline phases present in a mixture is based on the principle that from the measured diffraction intensities the amount of the crystalline phases in the mixture can be modelled. In quantitative Rietveld analysis we assume that the pattern contains only crystalline phases, whose concentration is refined. Adding to the sample a known weight of a standard, the assumption is checked. In the case that the weight of the standard is higher than expected, the percentage of the crystalline phases is adjusted, with the addition of an amorphous phase. To note, the amorphous content is given by difference, and no further information on its homogeneity or nature is obtained. 2.8 X-RAY FLUORESCENCE (XRF) ANALYSIS 2.8.1 XRF spectroscopy: conventional source X-ray fluorescence spectroscopy (XRF) is a quantitative analytical technique that is used to determine the elemental composition of a material. XRF is based on the property of atoms to emit X radiation characteristic of the element when they are excited by an X-ray beam. Fluorescence is induced by a beam of primary electromagnetic radiation with energy of the order of tens of keV. It is a multielemental experimental technique, that is, it allows the simultaneous detection of most of the elements present in the sample under investigation (major, minor and trace elements). In this work, the elemental composition of all the grain sizes of the considered WtE plants was analysed by XRF. The BA were crushed and ground with an agate ball mill until a fine homogeneous powder with grain size < 0.063 mm was obtained. Tablets for conducting XRF analyses were prepared using 3 grams of BA ground with 7 grams of boric acid powder. The tablets were analysed at Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (Università di Bologna) with a WDXRF Axios PanAlytical spectrometer, equipped with a Rh tube working at 4 kW. The analyses were performed on both major elements (expressed g/100g) and trace elements (expressed in g/Kg). 30 2.8.2 µ - XRF spectroscopy: synchrotron radiation XRF done with conventional methods gives a bulk composition, average for the powdered tablet. The intensity and focussing which can be obtained from a conventional X-ray source are not sufficient to perform an analysis at the local scale. This can be overcome when synchrotron radiation is used. Synchrotron radiation is an electromagnetic radiation produced when a charge particle of mass m (electron or positron) accelerated to relativistic velocity is being deflected in a magnetic field. When the speed of the charged particle increases to relativistic values (v ≈ c) a radiation is generated with several specific characteristics: 1) it is strongly polarised; 2) it has a very low divergence; 3) it possesses a large and continuous range of energies (it’s white), so scientists can pick whatever wavelength they need for their experiments, as infrared light, ultraviolet or X-rays (soft or hard); 4) it is very intense, several orders of magnitude greater than conventional X-ray tubes. Using synchrotron radiation to excite the analysed area for fluorescence analysis we have a very intense and focussed beam, so that areas as small as 50x50 µm2 can be analysed. Figure 2.8.2.1 Scheme of a synchrotron. Legend: 1) Linac; 2) Booster; 3) Storage ring; 4) Beamline; 5) Front end; 6) Optics hutch; 7) Experimental hutch; 8) Control cabin; 9) RF cavities. (www.diamond.ac.uk) In this work synchrotron radiation was used to make µ - XRF maps and, as described in the following chapter, XANES analyses, at the XRF beamline at Elettra Sincrotrone Trieste (ETS) (Figure 2.8.2.1). 31 Figure 2.8.2.2 (a) Photograph of the IAEAXspe instrument installed at the XRF beamline of Elettra Sincrotrone Trieste (# Iain Darby/IAEA). (b) Seven-axis motorised manipulator. (Artwork courtesy of Huber Diffraktionstechnik GmbH & Co. KG.) (c) Movement range of Theta/2Theta axes depicted in a horizontal cross-sectional view of the IAEA endstation (Karydas et al., 2018). In this work, the experiment has been conducted using both HE multilayer for the collection of µXRF maps, with standard 45°/45° geometry for fluorescence mode measurements, using an XFlash 5030 SDD detector (Bruker, Berlin, Germany). The flat surface of the BA sample embed in epoxy resin has been mounted on a Teflon sample holder, with also reference metal foils mounted on the side (perpendicularly) for the energy calibration of the monochromator (in transmission mode, using an Hamamatsu Si-photodiode S3590-09, 10x10 mm2, 300µm thickness). This setup was necessary to secure the sample and to have a system compatible with the working conditions of the Ultra High Vacuum Chamber (UHVC, 10-7 mbar) available at the XRF beamline. µ-XRF maps were collected with an incident beam energy of 14 keV and a beam size at the exit slits of 50x50 µm2 (H*V). Higher order harmonics contaminations were suppressed by a pair of parallel plane mirrors intercepting the beam in grazing incidence (Figure 2.8.2.2). 2.9 X-RAY ABSORPTION SPECTROSCOPY (XAS) Absorption spectroscopy refers to a number of experimental techniques used to acquire information on the electronic, structural and magnetic properties of the matter. They are based on the study of the variations of the linear absorption coefficient as a function of the energy of the incident photons. In the case in which X-ray are used as radiation we are talking about X-ray Absorption Spectroscopy (XAS). The linear attenuation coefficient depends both on the scattering phenomena (elastic or inelastic), and on the photoelectric absorption. In the range of energies used to perform XAS (1-40 KeV) the component due to the absorption clearly dominates that caused by diffusion; therefore, the 32 attenuation coefficient can be approximated as the coefficient of photoelectric absorption. On large energy ranges, absorption coefficient varies according to a law reported below: 𝜇 ≈ 𝑑𝑍4 𝑚𝐸3 where Z is the atomic number of the target atom, m its mass, d the density of the sample and E the energy of the photon. Figure 2.8.1 Graph of the absorption coefficient of Pb in function of the energy of the photons of the beam (www.physics.nist.gov) In Figure 2.8.1 it appears that absorbance shows some discontinuity in correspondence of particular energies. These are due to photoelectric absorption by quantized energy values. When the energy of the beam is sufficient to extract the electron in a given energy level a large number of photons is absorbed by the sample, dramatically decreasing the number of transmitted particles. This consequently causes the appearance, in the vicinity of that particular energy, of a discontinuity in the absorption spectrum. By studying these seemingly irregular structures and their energy distributions, it is possible to obtain that of the innermost electronic shells of the various chemical elements. Moreover, sinusoidal oscillations of the absorption coefficient occur around the value assumed in the peak, that is, of the presence of a fine structure. 33 When a XAS spectrum is analysed, is possible to obtain different information depending on the considered range of energy; for this reason, is convenient to divide the spectrum into three distinct regions: • Pre-edge region: limited energy range to a few eV before the absorption edge. It’s possible to detect the presence of weak discontinuities (pre-edge peaks) due to transition of core electrons to other bound states. • X-ray Absorption Near Edge Structure (XANES): it is the part of the spectrum which extends from 0 to 50 eV above the absorption edge; the combined study of XANES and pre-edge provides information on geometric and electronic local configuration. In other words it is particularly useful to obtain information on the state of chemical bond between different atoms of the sample and is strongly affected by the oxidation state of the absorber atom. This was the technique used in this work. • Extended X-ray Absorption Fine Structure (EXAFS): defines the region of the spectrum between 100 and 1000 eV beyond the absorption edge. From EXAFS analysis is possible to determine the geometric structure of the sample in the immediate vicinity of the absorber atom (up to 10 Å). Figure 2.8.2 Example of an XAS spectrum of Fe and its components (www.commons.wikimedia.org) Since XANES is a much larger signal than EXAFS, XANES spectra can be collected even in sample containing lower concentrations of the target element. The interpretation of XANES spectra is complicated as there is not a simple analytic or physical description of XANES. However, the spectra can be interpreted by comparison with reference samples, and, as the edge position and shape is 34 sensitive to formal valence state, ligand type, and coordination environment, the XANES spectra can be used as a fingerprint to identify phases. An important and common application of XANES is to use the shift of the edge position to determine the valence state; the heights and positions of pre-edge peaks can also be reliably used to empirically determine oxidation states and coordination chemistry (Figure 2.8.2). A major advantage in XANES is to be element sensitive, and to detect an element even in ppm concentrations. Also, even when a given element under the beam is represented by more than one phase, a deconvolution can be done to assess the different contributions under the beam of the phases where the element is present. In this work, some PTE (Cu, Cr, Zn, Pb, Ni, and Co) were analysed by XANES in order to investigate their oxidation state and the mineralogical environment in which they were hosted. XANES measurements were conducted at the Elettra XRF beamline. The experiment has been conducted using Si111 monochromators, with standard 45°/45° geometry for fluorescence mode measurements, using an X-Flash 5030 SDD detector (Bruker, Berlin, Germany). All spectra were collected using 5 seconds per step and a variable energy step as a function of the energy: Large step (5 eV) in the first 200 eV of the spectrum, smaller step (0.2 eV) in the near-edge region and a k-constant step of 0.05 Å-1 further above the absorption edge. Multiple spectra have been collected and merged in order to increase the signal to noise ratio. The oxidation state will be determined using least-squares Linear Combination Fitting (LCF) based on reference spectra collected on compounds of known oxidation state. Background removal, normalisation of XANES spectra and LCF analyses will be performed using the Athena software package. 2.10 LEACHING TEST The leaching test is a special type of chemical extraction. The material (soil, waste or sludge) undergoes a chemical attack with a reagent (liquid) in order to assess, through the analysis of the eluates, the elements released from the solid sample. The test makes it possible to estimate the potential long-term release of the compounds contained in soils or wastes, particularly those that could constitute potential pollution of the environmental matrices. In this work, leaching tests and analysis of the leachates were performed following the UNI EN 12457-2:2004 “Waste Characterization - Leaching - Compliance test for granular waste and sludge leaching - Part 2: Single-stage test with a liquid/solid ratio of 10 l/kg for materials with particle sizes less than 4 mm (with or without size reduction)”, which in this case has been adapted for BA assessment. This is a single-stage test called “batch leaching method”, where a given volume of sample is placed in a volume of leachate solution for a given period of time. This method requires 35 some type of agitation to ensure constant contact between the sample and leachate. At the end of the leaching period, the liquid is removed and analysed. Following guidelines which indicate a liquid to solid ratio of 10 to 1 (L/S = 10:1), the test was conducted in 50ml falcons into which 3g of BA and 30ml of ultrapure water (Milli-Q ® 18.2 MΩ.cm at 25 °C and TOC < 5 ppb). The test was carried out on the particle size classes below 4mm from all the five WtE plants examined. Three replicates were prepared for each grain size class for greater accuracy of the data and a “blank” sample containing only 30ml of ultrapure water. The entire experimental procedure can be summarised as follows: ● the samples were placed in rotator shaker for 24h at 30 rpm; ● after 24h, each sample was centrifuged at 3600 rpm for 10 minutes in order to separate the eluate from the solid fraction; ● the samples were filtered and the eluates were collected; pH, temperature and electrical conductivity were noted; ● the samples were acidified with 3 drops of nitric acid The leachates were diluted 1:2 and then 1:100 and were analysed by atomic absorption, ion chromatograph, and ICP-MS (analytical techniques that will be explained in detail later) in order to evaluate major elements, ions, and minor or trace elements. 2.11 SEQUENTIAL EXTRACTION PROCEDURE (SEP) The SEP is a procedure where the sample undergoes a series of chemical etching to dissolve the solid phases, in response to their chemical behaviour. With this procedure, we may detect minor phases which from the X-ray diffraction of the original sample could be overlooked. The Standards, Measurements and Testing (formerly BCR) program has proposed a three-step sequential extraction procedure for the analysis of sediment contaminants (Rauret et al., 1999). The procedure consists of three steps in which the sample to be analysed is attacked sequentially by different reagents and the eluates are analysed to assess which elements and in what amounts have passed into solution. Several studies in the literature (Abramov et al., 2018; Alam et al., 2019; Haberl & Schuster, 2019; Pérez-Martínez et al., 2019; Tong et al., 2020; Akyniemi et al., 2020) apply and modify BCR 176 for the study of BA and FA. In this work, a sequential extraction procedure was developed based on the material’s response to different chemical attacks which will be described below. SEP was conducted on the Piacenza BA (sampled in 2019) and the Parma BA (sampled in June 2021). Specifically, for Piacenza material from 0.2 - 0.3mm grain size was analysed, while for Parma 2021 three particle size classes (0.063-0.2, 0.3 - 0.5, 2 - 4 mm) and a bulk made from the particle size 36 classes < 4mm were analysed. For each sample, 30g of material was taken and quartered to obtain samples of 1g each. The final procedure consists of 5 steps described below, each of them promoting dissolution of a given portion of the material (Figure 2.11.1): ● STEP 1 (water-soluble fraction): the first step aimed to removing water-soluble phases, such as hydrated phases (ettringite). In centrifuge-tubes (50ml), 1g of BA and 40 ml of ultra-pure water were added. The samples were placed in an oscillating shaker at 30rpm for 16h (overnight) at room temperature. Then, the solid fraction was separated from the liquid fraction by centrifugation at 3000g for 20min (or until all suspended particles were precipitated). Through a filter apparatus with a vacuum pump, the eluate obtained was filtered, collected and stored with 3 drops of HNO3 at a temperature of 4°C. ● STEP 2 (carbonate fraction): the second step is aimed to removing carbonate fraction, such as calcite and vaterite. In the centrifuge-tube (50ml), 40ml of 5mol/l acetic acid was added to each solid residue from the previous step. The samples were placed in an oscillating shaker at 30rpm for 16h (overnight) at room temperature. Then, the solid fraction was separated from the liquid fraction by centrifugation at 3000g for 20min (or until all suspended particles were precipitated). Through a filter apparatus with a vacuum pump, the eluate obtained was filtered, collected and stored at 4°C. Solid residues are washed with ultrapure water three times in a centrifuge and then proceed to the next step or are stored to conduct chemical-mineralogical analysis. ● STEP 3 (reducible fraction): the third step is aimed to removing reducible fractions, such as Fe – Mn oxyhydroxides. The residues from the previous extraction step are added to 40 ml of hydroxylammonium chloride 0.5mol/l. The samples are placed in an oscillating shaker at 30rpm for 16h (overnight) at room temperature. Then, the solid fraction is separated from the liquid fraction by centrifugation at 3000g for 20min (or until all suspended particles are precipitated). Through a filter apparatus with a vacuum pump, the eluate obtained is filtered, collected and stored at 4°C. The solid residues are washed with ultrapure water three times in a centrifuge and then proceed to the next step or are stored to conduct chemical-mineralogical analysis. ● STEP4 (oxidable fraction): this step is aimed to removing oxidable fraction, such as organic matter and sulphide. solid residues from the third step are transferred into glassy beakers with 10 ml of hydrogen peroxide. beakers are covered with a glass watch and digested at room temperature for 1h with occasional manual shaking. Digestion continues for 1h at 85°C in a thermostatic bath, then reduce the volume to less 3ml by further heating of the uncovered 43 the European Council Regulation 2017/997 concerns the heavy metals glass and mineral-bearing phases, their identification and characterization, and their weathering behavior (EU 2017/997). It is established that the smaller portion of the bottom ashes is the more polluted (Alam et al., 2020; Wiles, 1996). This was systematically verified in a recent investigation that sorted the BA in a range of different grain sizes. BA sorting produces new waste with the further disadvantage that smaller sized grains provide a larger reaction surface and, possibly, higher leaching of heavy metals already present at significant concentrations (Alam et al., 2020; Alam et al., 2019a; Caviglia et al., 2019; Loginova et al., 2019; Šyc et al., 2020). Recovery of the smaller fraction of the BA was proposed in regard to pyroxene glass ceramics by heating at a high temperature (Bourtsalas et al., 2014). However, characterization through different sizes of the BA is required to plan any process of recovery. Previous investigations focused on the characterization of the mineral phases (Alam, et al., 2019a; Bayuseno & Schmahl, 2010)or the analysis of the portions sieved from bottom ashes (Caviglia et al., 2019; Šyc et al., 2020). A systematic investigation regarding mineralogy, composition, and grain size, to constrain the host for the potentially toxic elements (PTE) is still lacking. It is not clear whether the PTE are always concentrated in small grain sizes or whether their presence primarily depends on the waste input or the type of plant (Hyks & Astrup, 2009). This study compares the average mineralogical and chemical composition for each fraction divided by grain size, using results from the literature and new data from the waste-to-energy plant (WtE) located in Parma. X-ray diffraction, chemical analysis of major and minor elements, and optical and electron microscopy, together with microprobe analysis observations, are used to clarify the trends followed by PTE in terms of grain size and BA mineralogy. The aim of this study is to determine how grain size affects the distribution of the different elements and any possible reuse and recycling implication 2. Materials and Methods 2.1 The Bottom ash sampling and sieving Municipal solid waste incineration (MSWI) bottom ash was collected from the WtE plant of Parma (northern Italy), which is located in the first suburbs of the city in the PAIP (Polo Ambientale Integrato per la gestione dei rifiuti di Parma—Environmental Integrated Area for waste management). Designed and built by Iren Group, the plant has been operating since 2014, covering about 150.000 tons/year of material in 2019. The main feedstock waste includes a dry fraction selected from undifferentiated municipal solid wastes (70.000 t/year); special unrecycled wastes (18.000 t/year); discharges from waste recovery and disposal (15.300 t/year); sanitary wastes (3.500 t/year); cemetery wastes (200 t/year); industrial, handicraft, and commercial processes wastes (3.000 t/year); and dried 44 sewage sludge (20.000 t/year). The plant produces about 32.000 t/year of BA, as well as slag and fly ash (about 20% of the ashes). Five samples, each weighing about 600 g, were taken, blending a larger amount of material from different points of the bottom ash pile located inside the plant on five different days (1–5 December 2018) to consider the variability of the material. The individual samples were mixed; the total sample of about 3 kg of fresh BA was dried in the oven at 50° C for 24 h and sieved in order to assess the grain size distribution. The openings standards used were chosen according to European standards for aggregate EN 933–2 (Ente Italiano di Unificazione, 2020), and the grain size used for further investigation was divided into nine classes (<0.063, 0.2, 0.3, 0.5, 1, 2, 4, 8, >16). The cumulative grain size distribution is shown in Figure 3.1.1.1. Figure 3.1.1.1 Cumulative particle size distribution and comparison with the Fuller curve and with literature data (Syc et al., 2018; Funari et al., 2015; Caviglia et al., 2019; del Valle-Zermeno et al, 2017; Fuller et al., 1907). 2.2 X-ray Fluorescence Spectrometry (XRF) The bulk composition was measured for each granulometric class by means of X-ray fluorescence spectrometry (XRF). About three grams of the dried and milled material was used. Before analysis, each sample was first pressed in a boric acid binder to obtain a thin-layer pressed powder pellet (37 45 mm in diameter). A sequential wavelength dispersive X-ray fluorescence (XRF) spectrometer (AxiosPanalytical), equipped with a 4 kW Rh tube and SuperQ 3.0 software, was used. Total loss on ignition (LOI) was gravimetrically estimated after overnight heating at 950° C. The analytical results in Table 3.1.1.1. are provided with measured vs. certified values of the certified reference material (CRM) BCR-CRM176R. The estimated precision for elemental determinations is better than 5% for all elements, except those occurring at concentrations lower than 10 mg/kg, for which the precision is comparably worse (10–15%). 2.3 X-ray powder diffraction (XRPD) phase analysis X-Ray Diffraction (XRD) was performed on each of the sieved portion, and on few mm-sized grains chosen in function of the optical appearance. A Bruker D2 Phaser powder diffractometer with Cu Kα (λ=1.54178 Å) radiation, 30 kV and 10 mA, Ni filtered, 2θ between 5 and 70°, with steps of 0.02° and a sampling time of 1 s was used. The diffractometer acts with a θ-θ focalizing geometry and takes advantage of a solid-state detector. A sample rotation of 30 rpm was applied to minimize crystal preferential orientation effects. The diffraction patterns were identified using the Bruker software EVA and the Crystallography Open Database (COD). The complexity given by the number of mineralogical phases hindered a quantification through Rietveld refinement of all the phases present. The major crystalline phases, found in all samples, were quantified using the GSAS 2 software package (Toby & Von Dreele, 2013). The amorphous content was estimated by Rietveld analysis (Rietveld, 1993) using high purity Al2O3 corundum (10 wt %) as an internal standard. The refined phases and their abundance are listed in Table 3.1.1.2. 2.4 Optical and SEM-EDS microscopy Twelve large fragments (>8 mm) were embedded in epoxy resin and cut longitudinally to obtain thin and polished sections for the analysis. The embedded grains were selected to avoid unburnt and refractory materials, which were instead part of the powder analyzed by XRD and XRF. The sections were first observed by a polarized stereomicroscope (BX51, OLYMPUS), and then with a Scanning Electron Microscope coupled with Energy Dispersive System (SEM-EDS) JSM IT300LV Jeol 6400 equipped with an Oxford EDS microprobe. Microprobe analysis was performed with operating conditions 20 or 25 kV and 1.2 mA current, ~1µm beam diameter and 75 s counting time. Analyses at 25 kV were performed in order to enhance the contribution of the higher energy peaks in metals and heavy metals. 2.5 Statistical analysis 46 A descriptive statistic is applied to selected chemical and mineralogical results based on grain size as a discriminant variable and used for comparative analysis with two suitable works recently carried out by Caviglia et al. (2019) and Loginova et al. (2019). The correlation was investigated by calculating the linear regression (r, Pearson) and Spearman’s rank p order correlation coefficient. Statistical analysis of data distributions was performed using SPSS software (IBM corporation, 2017) and reported in APPENDIX I. 3. Results 3.1 Grain size distribution In Figure 3.1.1.1, the granulometric curve of samples is shown and compared with that of other incinerators with similar technology and conditions as reported by Caviglia et al. (2019), Funari et al., (2015), Šyc et al., (2018) and del Valle-Zermeño et al. (2017). The Fuller curve, which represents the optimal aggregate distribution curve in terms of density and strength, is also plotted (Fuller & Thompson, 1907). Some of the difference may come from the sampling procedure: the curves vary in dependence on the portion of the ashes pile which is sampled, overestimating the larger size in the lower portion (A. F. Gualtieri, 2000), but for all the granulometric plots, the fraction lower than 4 mm accounts for about 55 wt%. In particular, the cumulative particle size distribution of Parma shows that the most of BA (about 60%) lies in the range of 2-9 mm (range of coarse sand and gravel) while a 20% of the total weight has a grain size <2 mm and another 20% is the fraction >9 mm. A difference exists in the portion below 1 mm, which is just 6 wt% in Parma and Funari et al. 2015, whereas it is up to 20 wt% in others (Loginova et al. 2019). Comparing the shape of the Fuller curve to our samples, we have a lower percentage - about 5-10 wt% -of fine material (below the 3 mm). 3.2 Chemical analysis of MSWI bottom ash The bulk chemical composition with grain size is reported in Table 3.1.1.1. Pearson’s r-value and the Spearman rank p to test correlation between elements and with grain size is reported in APPENDIX I. In the Parma bottom ashes, Si is enriched in the larger grains and Ca in the smaller ones. There are several elements that are positively correlated with Si or with Ca. The positive trend with Si is followed by Rb and Zr, and, among major elements, by Al, Fe, K, and Mg, when only the portions smaller than 2 mm are considered. In this case, the correlation is strong (R2 > 0.9). Several other elements are positively correlated with Ca, and negatively with grain size: they are S, Cl, Zn, Cu, Ba, Pb, As, Sn, Ti, and Sr. Few elements, Cr, Ni, V, and Ce, do not seem to be related to Si or Ca. 47 major elements (g/100g) grain size (mm) >16 8-16 4-8 2-4 1-2 0.5-1 0.3-0.5 0.2-0.3 0.063-0.2 <0.063 SiO2 46.23 45.82 38.95 37.75 35.91 31.72 29.20 25.71 24.85 23.71 CaO 21.60 21.78 24.79 24.66 24.63 26.67 28.41 29.67 30.12 30.05 Al2O3 8.59 8.26 8.92 10.39 10.05 9.63 8.96 8.27 8.46 8.27 MgO 3.71 3.95 3.64 4.33 4.42 3.91 3.59 3.26 3.15 3.23 Fe2O3 3.04 3.01 3.60 3.63 4.05 3.74 3.48 2.64 2.49 2.21 Na2O 3.92 3.69 2.78 2.49 2.36 2.20 2.18 2.14 2.26 2.20 P2O5 1.52 1.30 1.59 2.22 2.11 2.10 2.19 2.00 1.91 1.82 K2O 1.21 1.29 1.26 1.36 1.45 1.35 1.29 1.23 1.19 1.11 TiO2 0.69 0.64 0.78 0.86 0.90 0.97 0.92 0.90 0.90 0.90 MnO 0.09 0.08 0.11 0.09 0.10 0.10 0.10 0.09 0.09 0.10 LOI 9.40 10.19 13.60 12.22 14.02 17.62 19.69 24.08 24.58 26.40 Minor and trace elements (mg/Kg) S 8070 7780 9600 9500 10900 12840 14780 16910 17740 16420 Cl 5430 5430 7420 8050 8236 9780 10120 10530 10960 11600 Cu 1261 1413 1104 1669 1335 1640 1885 1664 1637 2041 Zn 1380 4400 1660 3630 3830 4270 5750 5940 6830 8740 Ba 955 907 1098 1684 1461 1681 1618 1631 1529 1879 Pb 1354 409 312 545 676 800 802 913 981 1172 Cr 880 629 573 434 651 644 697 592 621 627 Sr 429 378 436 681 499 485 517 571 568 572 Zr 256 212 186 207 196 173 169 155 156 143 Ni 119 183 140 135 174 144 179 132 134 160 Co 27 27 32 25 62 51 57 44 44 43 V 61 69 73 84 84 90 79 78 78 79 As 54 26 41 36 47 52 56 59 59 74 Ce 37 44 41 46 47 48 36 29 38 51 Sn 19 17 19 44 36 53 43 49 58 91 Rb 32 34 31 30 32 30 27 27 25 24 La 18 35 13 8 25 30 21 6 14 16 Y 14 16 16 17 19 15 14 12 12 11 Nd 18 19 10 10 22 18 20 2 19 5 Mo 15 10 15 11 17 14 13 15 14 14 Ga 14 13 12 13 13 13 14 14 13 14 Nb 11 10 11 12 12 11 10 10 11 10 Sc <3 6 10 15 10 6 13 14 18 14 Th 13 7 6 5 7 7 7 8 9 9 Hf <3 7 6 4 3 <3 <3 <3 <3 <3 U <3 3 <3 <3 <3 <3 <3 <3 <3 <3 Table 3.1.1.1 X-ray fluorescence spectrometry (XRF) analysis of major, minor, and trace elements for the bottom ashes (BA) samples of Parma waste-to-energy (WtE) plant divided by grain size. Elements are in mg/kg, but major elements are expressed as g/100 g of their oxides and loss on ignition (LOI) values in %. The measured vs. certified concentrations of the certified reference material (CRM), BCRCRM176R, is provided with the same unit of measure (n.a. is not available). Thus, we find a Si-trend, which is followed by lithophyle elements, i.e., those having an affinity for Si, incorporated in silicates, and a Ca-trend, for elements with an affinity for carbonates and sulfates (Ca, Ba, Zn, and Pb), sulfides (Sn and As), oxides (Ti), or possibly to the unburnt organics (LOI, Cl, and S). Si-and Ca-trends are also present in other papers where the composition was determined with grain size. The differences with these observations are that Loginova et al. (2019) showed a strong correlation with Ca and S for Ni and Cr, and Caviglia et al. (2019) showed that Ni, but not Cu, follows the Ca-trend (Table S1). Moreover, the positive correlation with Si for Fe, Mg, K, and Al in the smaller grains is not confirmed; in Loginova et al. (2019), Fe has a negative correlation with Si. Within the above correlations, there is a strong differencein the actual compositional values (Figure 48 3.1.1.2). Si vs. Ca ch anged with a similar slope in this work and in that of Loginova et al. (2019), but shifted to lower Ca content in the work of Loginova et al. (2019); similar trends are found by Caviglia et al. (2019) but for the three finer grain sizes, which show higher Ca content than expected following the trend of Parma (Figure 3.1.1.2 a). From the analyses of smaller grains, it appears that Ca from different plants changes similarly with S, with an apparent deviation from the main trend (Figure 3.1.1.2 b). Pb and Zn follow a similar trend in the work of Loginova et al. (2019) and in this work, but they follow a different trend in the work of Caviglia et al. (2019) (Figure 3.1.1.2 c). No correlation between S and Cr is found in any studies. It is likely that these differences in chemical composition may come from the waste input and different burning processes of the WtE plants, despite the fact that a correlation between final composition and waste input may be very difficult to predict with current knowledge. Figure 3.1.1.2 Comparison between a) Si vs Ca, b) S vs Ca, c) Pb vs Zn, values for this work (green bullet) data from Loginova et al. 2019 (red squares) and Caviglia et al. 2019 (dark squares). 49 3.3 XRPD and Rietveld analysis All of the X-ray powder diffractions show heterogeneous assembly of several crystalline phases, together with significant glass content (Figure 3.1.1.3). To identify the mineralogical phases, in addition to the standard X-ray diffraction pattern made on the different grain-sized portion, selected on the basis of their aesthetic appearance, they are taken from the total sample and discussed. The main goal of this procedure is the characterization of specific phases that are hardly recognizable due to their small quantities inside the sample. Microscopic images of the isolated clasts and their identification with XRD analysis are reported in APPENDIX II. Their composition is very heterogeneous and is represented by small pieces of green, brown, or transparent glass (point 3); white spongy granules of hydroxyapatite of bone residues (point 5); pieces of non-combusted piece of metal (point 4); and gray aggregates with red or dark areas, which are the typical product of the burning processes. The mineral phases found in these grey clast resemble those noted in the bulk sample and most of the portions after sieving. Figure 3.1.1.3. XRD patterns made on different grain sizes. Alumina (Al2O3) standard is used. 50 Phase identification was biased by the number of overlapping peaks, which concealed the peaks of the minor phases. Moreover, isomorphic substitutions in plagioclase, gehlenite, phosphates, and sulfates give rise to a shift in peak positions, again hindering correct identification. In Table 3.1.1.2, quantitative Rietveld analysis was conducted on the few phases that could be univocally identified. The results of the Rietveld refinement are given in weight percent normalized to 100%, including the amorphous fraction estimated with the aid of the corundum internal standard. As shown in Table 3.1.1.2, the amorphous phases are the main constituents in BA. The amorphous phase is higher in the larger grain sized portions, between 75 and 70 wt%, andlower in the smaller ones, between 60 and 65%. The residual glass likely explains the higher amorphous phase content in the larger grains. Crystalline silicates (quartz and melilites) are present in higher percentage in larger grains, whereas carbonates, calcite, and vaterite occur more in smaller sized fractions. As expected, this agrees with the chemical analytical results, but as discussed below, most Ca and Si are present within the amorphous phases. Ettringite is concentrated more in the finer fractions, whereas less abundant hydrocalumite,strätlingite, and iron oxides appear to be unrelated to grain size. Calcite is the only crystalline phase present with a concentration higher than 10%. Its concentration in lower grain sized portion is likely related to the small size of crystals, which are formed during the carbonation process in air. Compared to other investigations, a difference in a minor content of feldspar is evident (Bayuseno & Schmahl, 2010; Loginova et al., 2019; Wei et al., 2011a), whose place is partially taken by Ca-Al-Si phases, such as ettringite, strätlingite, and hydrocalumite. Moreover, sylvite, another commonly found phase, is missing here. The amorphous phases here are more present than those in the works Bayuseno and Schmahl (2010) and Alam et al. (2019a), who found an amorphous of 33 and 36 wt%, respectively, but they are similar to those identified by Caviglia et al. (2019), i.e., about 70%. An intermediate value was found by Wei et al. (2011a) of about 50%. Phases Grain Size (mm) < 0.063 0.063-0.2 0.2-0.3 0.3-0.5 0.5-1 1-2 2-4 4-8 8-16 >16 Calcite 10 11 10 9 8 8 5 7 5 7 Quartz 3 4 2 6 3 5 6 6 4 5 Stratlingite 2 2 2 2 2 1 1 1 1 1 Ettringite 4 6 5 3 3 2 1 1 3 3 Hydrocalumite 3 4 4 4 3 3 3 3 3 2 Anorthite 2 2 2 7 2 3 3 2 1 2 Vaterite 3 3 4 4 2 3 1 2 2 2 Gehlenite 2 3 3 2 2 2 2 2 2 2 Hematite 1 1 1 1 3 1 < 1 < 1 < 1 < 1 Magnetite < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 Crystalline 30 36 33 36 28 27 23 24 20 25 Amorphous 70 64 67 64 72 73 77 76 80 75 Table 3.1.1.2 Rietveld refinement quantitative phase analysis (wt%) on different grain size. The estimated error is ±1. 51 3.4 Bottom ash morphology 3.4.1 Optical observation Optical observation was done on few grains, chosen for different colour and lustre, from the portion larger than 4mm. Similar grains were also analysed by XRD (APPENDIX II). The grain colour varies with the crystalline and amorphous phase content, as revealed by XRD. The few whitish grains were made of hydroxyapatite, likely by the burning of cemetery residuals; green or colourless glass come from residual glass, which did not react during incineration. The rounded reddish-grey grains, which are most abundant here, in Chimenos et al., (1999,2003) and in Wei et al., (2011) are most made by a heterogeneous aggregation of residual refractory material and metals coexisting with crystals and amorphous (Figure 3.1.1.4). The amorphous acts as a matrix that binds the crystalline and metallic fractions of the original waste and the new-formed minerals. The original waste grains show rounded edges, indicating partial reabsorption (Figure 3.1.1.4 a), whereas new formed crystals are often present as sharp needles within the glass, like the wollastonite crystals in Figure 3.1.1.4 b. Vesicles and bubbles appear indicating that some degassing occurred (Figure 3.1.1.4 c and 3.1.1.4 g). XRD and subsequent SEM-EDS analysis showed that the grey grains take their colour for the coexistence of gehlenite and wollastonite, mingled with metal, whereas the red portions take their colour from Fe oxides (Table 3.1.1.2 and APPENDIX III). Secondary carbonation is present as an external, fine grey cohesive material that coats the rounded clasts (Figure 3.1.1.4 f). 3.4.2 SEM-EDS investigation SEM backscattered electron images show almost invariably crystals within an amorphous matrix. The prevailing amorphous was investigated in further detail. About 400 EDS point analyses were done on different amorphous areas, sampling five polished sections sized about 8-10 mm; in each five areas were examined, for a total of 20 areas. The point analyses on the amorphous are plotted in the ternary diagram SiO2-CaO-Al2O3 in Figure 3.1.1.5, together with the bulk XRF composition for the 9 granulometric classes (red crosses). The amorphous material is made of an extreme heterogeneous composition, coexisting unmixed at the sub-millimetre scale even within the same grain. This kind of mingling, well known in igneous petrology is related to the crystal structure of silica-rich and silica-poor melts, here occurring at the microscale (Rankin, 1915). The composition of the amorphous within each volume is homogeneous (Figure 3.1.1.4). Optically, this is apparent in the coexistence of reddish and whitish glasses. The chemical composition of the glassy materials is reported in the SiO2-CaO-Al2O3 ternary diagram. Most amorphous compositions fall near or above the cotectic lines, with a crowding on the ternary 52 minimum; this suggests that the amorphous glass forms from melt at eutectic conditions. About 80% of the analyses falls within the field with cornered by pseudowollastonite-gehlenite-larnite. As shown in Figure 3.1.1.4 the average composition of the larger grains is Si-richer than almost all the analysed glasses. Figure 3.1.1.4 photomicrograph showing the inner part of the clasts cut longitudinally. Each of them appears different from the other in terms of morphology but we can observe frequently a part of a dark matrix (dm) (b,e,f,g) and within it areas of different color, sometimes white (c), yellow/red (e,f,d) or transparent (b,e). Many samples present little vesicles and bubble structures, indicating degassing processing (c), metallic, alloy or refractory inclusions (a,g) sometime with reaction rims (a). External grey crust surrounding related to carbonation is shown in figure (d). This likely occurs as XRF analyses consider also pure SiO2 residual glass, which was discarded in the analysis of the grains. The glassy matrix is the host of Na, K, and Mg, elements which are not 59 3.2 COMPARISON BETWEEN WtE PLANTS IN NORTHERN ITALY In this second investigation the results on the first investigation on the Parma WtE plants are discussed with further data from 5 WtE plants from northern Italy. XRD, XRF and TGA analysis were conducted for each grain size; the XRF analysis showed higher concentrations of PTE in the finer grain size and for this reason the granulometric classes < 4mm were used for leaching test. The main results were: 1) a notable similarity in the major element composition, in spite of the different locations and input fluxes; 2) a strong difference in the content of the amorphous phase, between the Ferrara and Forlì-Cesena incinerators, respect to the others; 3) a partial confirm of the trend between grain size and composition found in the first paper, with elements like Al and Fe showing different composition and grain size relations in the 5 incinerators; 4) a varying leaching of the minor elements, among which PTE, with results following a trend and of the same order of magnitude in the samples from each incinerator; 5) a general trend where PTE are released more in the smaller grain size portion, often with values above regulatory limits. The results obtained have been the subject of an article currently being submitted. The article is reported as paragraph 3.2.1. For simplicity, figures and tables have been re-numbered following the structure of this thesis. 3.2.1 Grain size and mineralogical constrains on leaching in the bottom ashes from municipal solid waste incineration: a comparison on 5 plants from Northern Italy Authors: Mantovani L1, De Matteis C.1, Tribaudino M.2, Boschetti T.1, Funari V.3,5, Dinelli E.4, Toller S.1,3, Pelagatti P.1 1Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale (SCVSA), Università di Parma, 43124 Parma 2Dipartimento di Scienze della Terra, Università di Torino, 10124 Torino 3Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (ISMAR-CNR), 40129 Bologna 4Dipartimento di Scienze Biologiche, Geologiche e Ambientali (BiGeA), Università di Bologna, 40126 Bologna 5Dipartimento di Biotecnologie Marine, Stazione Zoologica Anton Dohrn, 80121 Napoli Type: Article Journal: Frontiers Status: Submitted 60 Keywords: MSWI-BA, PTE, material characterization, leaching test, grain size analysis Abstract Introduction. Bottom ash (BA) from municipal solid waste incinerator (MSWI) are currently classified by the European Waste Catalogue as industrial non-hazardous waste. To promote their reuse, identification and characterization of the heavy metals bearing phases (both glass and minerals), as well as their weathering behavior must be addressed for what concern the chemical composition, mineralogical phases and in high concentrations and pollutants’ mobility. An important point is weather the results from a given plant can be generalized. Material and Methods. In this work BA from 5 northern Italy Waste to Energy (WtE) plants were sorted based on different grain sizes. The input waste of the plants is similar, coming from a culturally homogeneous area, and with similar collection management. For each grain size, a mineralogical, chemical and physical characterization has been done using of X-ray fluorescence (XRF), X-ray powder diffraction (XRD) and Rietveld refinement, Thermogravimetric analyses (TGA) and leaching test. Results and Discussion. We found that for major elements the average chemical composition of the incinerators is similar, with some difference in minor elements. Ferrara (FE) and Forlì-Cesena (FC) BA show portlandite, higher ettringite and lower amorphous than the Torino (TO) Parma (PR) and Piacenza (PC) ones. This affects the pH and the release and toxicity of the leachates. In FE and FC ashes ettringite is not dissolved, and we have low sulphate, but also Ni and Ba beyond reglementary limits, suggesting that Ni and Ba are present as hydroxides with portlandite, which dissolves. In TO, PR and PC Cr and sulphates are beyond limits, suggesting that Cr comes from dissolution in ettringite. Cu and Cl are always beyond limits; the dissolution of chlorides accounts just for 30-35% of the global Cl leachate. We observe that in the assessment of potential toxicity of the ashes mineralogy has an effect higher than the bulk chemical composition. Bulk and leachate composition show significant changes with grain size, but generally within an order of magnitude. Grain size sorting, although useful together with other techniques is not by itself able to comply with the PTE risk level. 1. Introduction The world generates 2.01 billion tons of municipal solid waste (MSW) per year, where it has been estimated that at least 33% is not managed in an environmentally safe manner. On average, each individual generates 0.74 kg/day but with strong regional differences. The global waste production is expected to grow up to 3.40 billion tons by 2050 (Kaza et al., 2018). 61 Waste management in Italy is regulated by the legislative decree n°152/2006, which implements main European directives on waste. According to the decree n°152/2006 MSW incineration residues need to be treated before they are disposed of. Landfilling is the most common method used to manage MSW, but landfilling has also concerns about groundwater pollution and soil contamination. Among the different waste management options, waste incineration is most important and widespread: it reduces the volumes and weight of the waste, and in WtE plants it also provides a bonus for energy production (Bawab et al., 2021) . Incineration produces two types of solid residues: bottom ashes (BA) and fly ashes (FA). The BA are the solid residues resulting from the combustion of household waste at the lower outlet of the furnace, after cooling in water tank, whereas the FA are the blown out fraction. In general, BA are about 20% of the total waste mass, and the FA, about 4% (Izquierdo et al., 2002). FA in Italy are usually excluded from recycling as they contain and release several hazardous elements (Setoodeh Jahromy et al., 2019). The BA are composed by a mineral fraction (80–85%), ferrous metals (5–10%), non-ferrous metals (2–5%), and unburned organic matter (CEWEP, 2016). The chemical composition of the bottom ash depends on the MSW feed characteristics and on the combustion system; the content of major elements resembles on average the content of these elements in the soil and lithosphere. The content of minor and trace elements varies depending on the plant; for most elements it is depleted, and for some like Zn, Pb, Cl it is highly enriched with respect to the equivalent average concentrations found in the soil and lithosphere (Dijkstra et al., 2009). Compared with other combustion waste, BA is highly enriched in Cu, Mn, Zn, Pb, Cr, and Ni (Izquierdo et al., 2002). In a circular economy perspective, large quantities of BA can be considered as urban mines, from which it could be possible to extract and recycle materials and chemical elements. In this point of view, the chemical and mineralogical characterization of BA is of paramount importance. In the last 20 years a number of studies investigated the technical and environmental properties, as well as recycling methods, leaching behavior, geochemical and petrological aspects of BA. All these literature data stressed the strong complexity of the BA due to an intrinsic heterogeneity of the material caused by a) selective collection of household waste, b) choice of incineration technology, c) furnace technology, d) cooling processes, e) maturation processes (among others:Zevenbergen et al., 1998; Eusden et al., 1999; Meima and Comans, 1999; Piantone et al., 2004; Ginés et al., 2009; del Valle-Zermeño et al., 2017; Dou et al., 2017; Alam et al., 2019). An important point debated by other authors is the incomplete knowledge of the chemical, physical and mineralogical composition of the BA, thus making any approach to reuse very approximate (di Gianfilippo et al., 2018; Huber et al., 2020). 62 For example, the finer iron particles mingled within the mineral fraction can hardly be separated by magnets and form several compounds containing heavy metals, which can potentially be recycled (Wei et al., 2011b) In recent years, much research has been conducted on the use of bottom ash as concrete in cements (Bawab et al., 2021; Kleib et al., 2021) in ceramic materials (Karamanov et al., 2021; Zanelli et al., 2021) and as fillers bituminous mixture (Suárez-Macías et al., 2021). It appears that any such application requires a focus on the chemical and physical features of the bottom ashes, giving attention to their strong heterogeneity, and to how their mineralogy affects the release of potentially toxic elements (PTE) in the environment. The characterization of waste from incinerators in terms of chemical and mineralogical variation is preliminary to possible reuse paths. A critical parameter was found to be grain size. It was shown that chemical composition changes with grain size, and that several PTE are concentrated in the finer fractions (Chimenos et al., 1999; Wei et al., 2011a; del Valle-Zermeño et al., 2017; Šyc et al., 2018, 2020). More recent investigation, however, contend the above as a general rule, showing for a given element differences in grain size vs composition in different incinerators (Caviglia et al., 2019; Loginova et al., 2019; Huber et al., 2020; Mantovani et al., 2021). A limit in the above investigations is the lack of a quantitative mineralogical composition with grain size, together with leaching tests to determine the possible release of PTE. In this work the chemical, physical and mineralogical analysis of BA from 5 plants located in Northern Italy has been done. The areas show similar MSW production, coming from a culturally homogeneous area, and with similar collection management. This will reduce the bias for possible differences in the input, which affect such comparison between incinerators. The samples were sorted according to the particle size and then analyzed to understand the variability coming from this parameter. XRD, XRF, TGA were performed on each portion, and followed by leaching tests. Grain size, elemental composition, and leachate products have been studied by PCA analysis. The aims of this work are: a) to describe the mineralogical and chemical variability between the bottom ashes from different WtE facilities, arising from plant performance during incineration and weathering; b) to provide general relations between grain size and composition, and between the different elements, for bulk and leachates, in order to assess the potential of grain size sorting for a higher value use of the ashes; c) to provide new suggestions to foresee potential leaching from the mineralogical composition of the ashes. 2. Material and Methods 2.1 MSWI bottom ash sampling and sorting 63 The samples come from 5 WtE plants located in northern Italy, 3 of them owned by Iren Ambiente SpA (Parma, Torino and Piacenza, hereafter PR, TO and PC) and 2 by Herambiente Spa (Ferrara and Forlì Cesena, hereafter FE and FC) (Figure 3.2.1.1). Table 3.2.1.1 summarizes for each plant the starting date of the activity, the type of waste input (tons/year) and the total weight of BA produced. Figure 3.2.1.1: geographical distribution of WTE plants investigated in this work. All the plants analyzed have a grate furnace technology that burns the waste for two to three hours at temperatures between 750 °C and 1000 °C. The input waste includes about 80% of undifferentiated fraction of separate collection (about 80%) and about 20% from special non-hazardous waste (industrial and household waste, sewage sludge, cemetery, biomedical waste, etc.). Only MSWI are burn in the Forlì plant (Iren Ambiente S.p.A., 2018; Hera Ambiente S.p.A., 2020). The BA sampling from the plants was carried out during a typical day of the process activity in different periods as reported in Table 3.2.1.1. Samples were randomly taken from a 2-3 m high stockpile which is representative of more than one month of accumulation. The homogeneity was checked by making X-ray diffractions on repeated days, without showing any significant difference. The samples were taken in May 2019 in PR, TO and PC WtE plants, and in April 2020, during the pandemic lockdown, in FE and FC. About 5 kg of BA samples were collected from each plant. Before 64 the analysis, the ashes were mixed, dried in an oven at 50°C for 24 h and sieved to different size classes. The sequential sieving (Φ: 16, 8, 4, 2, 1, 0.5, 0.3, 0.2 and 0.63 mm) was performed according to the European standards for aggregates EN 933–2(Ente Nazionale Italiano di Unificazione, 2020). WtE plant operating since (using this set up) waste input (tons/y) % of the waste type total waste input BA producted (tons/y) data related to sampling date for this work PARMA 2014 undifferentiated municipal solid waste (MSW) 126 317 79 159 832 32 904 2019 2019 special wastes (SW) 33 515 21 PIACENZA 2002 undifferentiated municipal solid waste (MSW) 110 041 96 114 231 21 135 2018 2019 special wastes (SW) 4 190 4 TORINO 2014 undifferentiated municipal solid waste (MSW) 457 603 81 562 269 118 969 2019 2019 special wastes (SW) 104 666 19 FERRARA 2008 undifferentiated municipal solid waste (MSW) 69 598 53 131 894 27 021 2020 2020 special wastes (SW) 62 296 47 FORLI 2008 undifferentiated municipal solid waste (MSW) 119 215 100 119 215 53 308 2020 2020 Table 3.2.1.1: waste input and output (only for BA) for each sampled WtE plant. Municipal Solid Waste: household and similar waste; Special Waste: waste from municipal sewage network and treatment, municipal construction and demolition waste, sanitary and cemetery wastes (Data from: Hera Ambiente S.p.A., 2020b, 2020a; Iren Ambiente S.p.A., 2018, 2020) The cumulative grain size distribution curves are reported in Figure 3.2.1.2. Aggregates larger than 3 cm were removed to avoid loss of representativeness and distortion of the analytical results. Figure 3.2.1.2: Cumulative particle size distribution of bottom ashes of the 5 plants analyzed. The dashed lines report the Fuller’s curves with n=0.4,0.5 and 0.6 ad dmax=20 65 2.2 XRD analysis X-Ray powder Diffraction (XRD) was performed on each sieved fraction. A Bruker D2 Phaser powder diffractometer was used, operating at 30 kV and 10 mA with Cu Kα (λ = 1.54178 Å) radiation. The collections were done at 2θ between 5 and 100°, steps of 0.02°, and 1sec/step sampling time. The diffractometer works with θ-θ focalizing geometry and takes advantage of a solid state detector. A 30 rpm sample rotation was applied to minimize crystal preferential orientation effects. The diffraction patterns were identified using the Bruker software EVA and the Crystallography Open Database (COD) (Table 3.2.1.2). GSAS 2 software package (Toby and von Dreele, 2013) was used to perform Rietveld analysis and quantify the major crystalline phases and the amorphous content. High purity Al2O3 corundum (10 wt%) was used as internal standard. APPENDIX IV reports the quantitative interpretation of XRD analysis with grain size for each WtE plant. mineral phases WtE plants Name Formula PR PC TO FE FC Calcite CaCO₃ x x x x x Vaterite CaCO₃ x x x x x Quartz SiO2 x x x x x Cristobalite SiO2 / / * / / Anorthite Ca(Al2Si2O8) x x x x x Bytownite (Ca,Na)[Al(Al,Si)Si2O8] x x x x * Albite Na(AlSi3O8) * * * / / Pyroxenes group ABSi2O6 / / x / / Akermanite Ca2Mg(Si2O7) * * * x x Gehlenite Ca2Al(AlSiO7) x x x * * Ettringite Ca6Al2(SO4)3(OH)12 · 26H2O x x x x x Hydrocalumite Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O x x x x x Portlandite Ca(OH)2 x x x x x Strätlingite Ca2Al2SiO7 · 8H2O x / / / / Apatite Ca5(PO4)3(Cl/F/OH) * * * * * Larnite Ca2SiO4 * * * x x Tobermorite Ca4Si6O17(H2O)2 · (Ca · 3H2O) * * * / / Sjogrenite Mg6Fe2(OH)16(CO3) · 4H2O / / / * * Magnetite FeFe2O4 x x x x x Ematite Fe2O3 x x x x x Table 3.2.1.2: XRPD identification of bottom ash. The minerals are arranged in the following sequence: (x) major minerals (*) minor or trace minerals, (/) not found or very doubtful presence. 66 2.3 XRF analysis The bulk composition of each grain size was measured using a wavelength dispersive X-ray fluorescence spectrometer (XRF), Panalytical Axios 4000, equipped with a Rh tube. About three grams of the representative samples were oven-dried at 50° C, homogenized and milled with an agate vibratory disk mill. Thin-layer pressed powder pellets for XRF analysis were prepared using a boric acid binder. The reproducibility, the general accuracy through calibration curve and corrections of the data are the same used in other works (Franzini et al., 1972; Toller et al., 2021). Major, minor and trace elements (SiO2, TiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, P2O5, As, Ba, Br, Ce, Cl, Co, Cr, Cu, Ga, Hf, La, Mo, Nb, Ni, Pb, Rb, S, Sc, Sn, Sr, Th, U, V, W, Y, Zn, Zr) concentrations are calculated using a calibration curve built on a large number of certified reference materials and offline correction of Loss On Ignition (LOI) values. LOI, which is correlated with the influence of humidity, organic matter, and water, was gravimetrically estimated after overnight heating the samples at 950°C in a muffle furnace (Heiri et al., 2001) 2.4 Thermo Gravimetric Analysis Thermal gravimetric analyses were conducted by means of a Perkin Elmer 8000 instrument equipped with a Pt-crucible (sample mass approximatively 3-5 mg) at a heating rate of 10 °C/min in the temperature range 35–800 °C. All the measurements were run under a constant flux of dry air atmosphere (30 mL/min). 2.5 Leaching tests and water elemental analysis Standard leaching tests and analysis of the leachates were performed following the UNI EN 12457-2 (Ente Italiano di Normazione, 2004), a test of compliance for the leaching of granular waste and sludge, which in this case has been adapted for bottom ashes assessment. The test is based on a one stage batch at a defined liquid to solid ratio for materials with particle size below 4 mm. Samples have thus remained in ultrapure water (Milli-Q ® 18.2 MΩ.cm at 25 °C and TOC < 5 ppb) for 24 hours under mechanical oscillation in a controlled environment. The analysis of the leachate samples were conducted using Ion chromatography (Metrohm Compact IC pro 881) for anions (Cl-, SO4-2, F- , Br-, PO43-), Atomic absorption spectroscopy (Thermo S Series AA Spectrometer) for cations (Ca, Mg, Na, K), and Inductively coupled plasma mass spectrometry (Perkin Elmer ICP-MS ELAN DRCe) for trace elements (Al, Ba, B, Cr, Co, Fe, Pb, Li, Mn, Mo, Ni, Se, Sr, Tl, Ti, V, Zn). Finally, the metal extraction (from the solid to the leachate) was calculated as Xlea/Xbulk *100 for each WtE plant in the grain size < 2 mm, where Xlea is the analytical determination of the a certain element on the leachate and Xbulk is the total concentration of the solid by XRF. 67 3. Results and discussion 3.1 Particle size distribution Figure 3.2.1.2 shows the grain size curves of the samples. In all the BA samples the larger fraction prevails: below 1 mm the sieved portion represents between 5 and 8 wt.% of the total mass, and 50% of the mass does not pass the at 4 mm sieve. This was also found in previous investigations (del ValleZermeño et al., 2017; Šyc et al., 2018; Caviglia et al., 2019). An exception is the PC plant, where there is a higher percentage of fine and medium sized particles (the grains passage is almost 80% at 4 mm). It is not clear whether this is due to the sampling methodology or the intrinsic heterogeneity of MSWI residues. In order to test the recyclability of BA in cementitious formulations, we compared our results with the optimum size distribution for concrete according to the Fuller curve, which represents the optimal aggregate distribution curve in terms of density and strength(Fuller and Thompson, 1907). The Fuller curve calculates the optimum percentage of a given particle diameter d as: P (d) =100(d/dmax)n. Three Fuller curves were calculated with an aggregate maximum value of dmax = 20 mm, i.e. the maximum opening sieves used here and n exponential factor n = 0.4, 0.5 and 0.6. In no case the distribution falls completely within the curves, as the smaller dimensions are underrepresented in our sampling. 3.2 XRD Tables 3.2.1.2 and APPENDIX IV show the mineralogical composition of the BA and their separated grain size classes. The bulk mineralogical composition of the ashes for each incinerator was obtained from that of each grain size and their proportion as: ci,bulk= ci,j*wj/wbulk where ci,j is the fraction of the mineral (i) in the sieved portion (j) (as reported in APPENDIX IV), wj the weight of the sieved portion and wbulk, the weight of the sum of the sieved portions. The minerals reported in APPENDIX IV are those most present, whose abundance could be refined by Rietveld analysis. A number of minor phases is also present, which either showed very faint peaks in XRD or could be detected just from microprobe analysis (Bayuseno and Schmahl, 2010; Mantovani et al., 2021). During Rietveld analysis it was shown that the inclusion of a higher number of phases leads to refinement instability, so that a compromise was necessary between the number of phases to be included and the number that could be refined. In some cases, identification of mineral phases was doubtful due to the overlap of identificative reflections associated to certain peaks (Table 3.2.1.2). Most evident is the amorphous content, which is higher in the BA of the three plants (TO, PR, PC) so as that it overtakes the entire quantitative of crystalline component. In these plants, the amorphous is over 75% on average, and ranges in different grain size between 67 and 88 wt%. In the plants of 68 FE and FC, instead, bulk amorphous is, on average, less than 35% (depending on grain size between 7 and 55wt%). Furthermore, there is a slight inverse correlation between the logarithm of the grain size and the amorphous content, with R2 = 0.64, 0.53, 0.41, for PR, PC, TO, respectively. For FE and FC the correlation is not significant (p>0.05) (for statistical value see APPENDIX VII). The large amount of amorphous is common in bottom ashes (among others Eusden et al., 1999; Bayuseno and Schmahl, 2010; Caviglia et al., 2019; Loginova et al., 2019; Šyc et al., 2020). More recently Mantovani et al. (2021) showed that several amorphous phases characterized by a different composition and formation, and likely micro-structure are present rather than a single homogeneous amorphous phase. Residual glasses coming from the input waste are most present in the larger grains, whereas in fine grain and in some areas of aggregates, partly melted glasses are also present. Microprobe analyses on these glasses portion showed that they are different in composition; in general, they coexist with crystals in eutectoid conditions, with the local composition depending on metal (transition, alkali and alkali earth) content. The lower quantity of amorphous material in FE and FC occurs together with higher calcite, quartz and feldspar. Also ettringite content is higher in FE and FC than the other 3 plants sampled, indicating a probable greater reactivity of these ashes in the aging process. FE and FC showed the presence of larnite and portlandite, probably due to the high Ca content and ascribable to carbonation reaction and cementitious material in the input feed. Among minerals, quartz, calcite, melilites, iron oxides and some alteration products such as sulphates, chlorides, and hydrated minerals are ubiquitous. An inverse relation with grain size is found in calcite, mainly in TO and PR incinerators (R2=0.95 and 0.82, respectively) and less in PC and FC (0.53 and 0.45). In FE bottom ashes, the relation is not significant, but the larger size shows a much lower calcite content than the finer portion. Calcite probably derives from secondary carbonation, during weathering in the temporary storage site, but we do not exclude that the higher calcite content in FE and FC may come from an unfinished decarbonation process during thermal decomposition. Portlandite, Ca(OH)2 is found only in the BA ashes from FE and FC as a product of rehydration of CaO. The Ca-oxide forms at a temperature of approximatively 700 °C at an initial atmospheric partial pressure (0.04 atm) and from the de-carbonation reaction (Criado et al., 2018): CaCO3 => CaO + CO2(g) In FC portlandite correlate with the amorphous content (R2= 0.72). Such positive correlation is also found, albeit with lower evidence also in with Ferrara (R2= 0.34). Ettringite, hydrocalumite and strӓtlingite were formed during weathering. Ettringite and hydrocalumite are ubiquitous, whereas strӓtlingite is found only in the PR plant. Ettringite in TO is positively related to calcite and hydrocalumite (R2= 0.82 and 0.83, respectively), and shows a 75 3.5 Leaching Tests Leaching tests were done on particle sizes below 2 mm, as XRF analyses showed that they are richer in PTE. The leaching was done on particles of different size, and their variability was analyzed by PCA. The results are reported in APPENDIX VI and APPENDIX IX. PCA analysis shows that the two major components describe more than 80% of the variability in all WtE. A number of ions, among which Cl, K, Li, Na and Cu show an opposite trend respect to grain size, i.e. show higher leaching in smaller grain sized samples. SO42follows Cl in TO, PR, PC and FC. In FE and FC the sulphates leached are one order of magnitude less than in other incinerators. Ni and Cr follow Cl and sulphates in TO, PR and PC, but not in FE and FC. Pb does not follow a definite trend, with little change with grain size. Al is leached in significant amount only in TO, PR and PC, but not in FE and FC. Marked differences in leaching behavior have been found between the two different owner corporation that is IREN for PR, PC and TO and HERA for FC and FE. Although generally the leaching is higher in smaller grain size portion, great difference, within one order of magnitude, is found. Higher differences are observed between WtE plants. Figure 3.2.1.8: percentage of released elements calculate as (Xbulk/Xlea)*100 for each WtE plant in the grain size < 2 mm 76 With respect to a given particle size, the leaching of an element has been compared to the total content in the bulk sample (from XRF analysis) and calculated in percentage (all referred to mg/kg of material). The most released element is Cl with a release percentage of about 70/90%, higher in the finer fraction (Figure 3.2.1.8 and 3.2.1.9, APPENDIX VI). Figure 3.2.1.9: a) correlation between the leached Na++K+ vs Cland b) SO42vs Ca2+ (mg/l). The extraction efficiency in the smaller portion is almost twice that in the larger one. In agreement with Alam et al. (2020) we suggest that Cl is present in very soluble salts, like NaCl and KCl, dispersed on the surface of the grains. This suggestion is confirmed by the linear relation found in leached Na+K with Cl (Figure 3.2.1.9 a), whereas such relation does not exist in the sample composition determined by XRF as most Na and K are likely caged within the amorphous and silicates structures. However, the amount of chlorides in leachate are considerably greater than the Na+K value (and not in a 1:1 ratio), suggesting that the release of Cl is not only attributable to the dissolution of the Na/K salts. Therefore, no diffraction peaks attributable to Na,KCl are found in XRD analysis, suggesting that not all the Cl is bound to Na and K in salts, and that a significant release of Cl may be originate by the dissolution of ettringite. Therefore, probably the contribution of ettringite dissolution is minor, due to the very similar ratio in Na+K/Cl in the 5 plants, in spite of the different amount and solubilization of ettringite (Figure 3.2.1.10). EDS analyses of the ashes from PR, (Mantovani et al., 2021) showed that Cl is often associated with silicate glassy phases. We suggest therefore that chloride is most released by dissolution of weakly bonded Cl at the surface of the amorphous phases. This would explain the higher leaching in smaller grains, with higher surface. 77 All tests exceeded the legal limits for Cl (Legislative Decree 152/06) suggesting that washing and selection of larger grains may be combined technique to reduce Cl for a correct reuse. S shows a release, about 30% for PR, PC and TO and 3% for FE and FC, with no dependence on the particle size. S is present in the ettringite structure which is observed in XRD in all the plants, especially in FE and FC. However the release in SO42is lower in the two HERA WtE plants, whereas the Ca is higher (Figure 3.2.1.9 b). Moreover, Al is released by at least two order of magnitude less in HERA than in IREN plants. Another relevant difference is that the measured pH in the leached IREN plants is between 10 and 11, whereas in the HERA plants it varies between 12 and 12.5.We suggest that in the HERA plants, the dissolution of portlandite, which is absent in the IREN plants, gives rise to a basic environment, where ettringite is less prone to dissolution. In the IREN plants, ettringite dissolves, with sulphate and Al hydroxide solubilization. Other elements like Mg and Fe do not show a significant leaching, indicating that they are bonded in non-soluble oxide or silicate structures. Figure 3.2.1.10: trend of the Na++K+, Cland Na+K/Cl in the leachate in function of the grain size (< 2mm) for the 5 WtE plants. 78 The different mineralogy in IREN and HERA plants, and the consequent different leaching in major elements has an effect also on minor elements. Minor elements are often present in solid solution within phases more or less prone to dissolution at different pH, and the dissolution of the host phases releases also the exsolved element. Therefore the release in minor elements is different in the different WtE plants, often by two order of magnitude. In a plant the leaching could be above legal limits, whereas in others it could be not (Table 3.2.1.3). Elements ClSO42FPO43Ba Cu Zn As Be Co Ni V Cd Cr Pb Se Legal Limits 100 mg/l 250 mg/l 1.5 mg/l 2 mg/l 1mg/l 0.05 mg/l 3 mg/l 50 ug/l 10 ug/l 250 ug/l 10 ug/l 250 ug/l 5 ug/l 50 ug/l 50 ug/l 10 ug/l WtE plants grain size (mm) mg/l ug/l PR 0.063 - 0.2 703 438 0 0 0.04 0.12 0.06 0 0 0 8 2 0 458 6 17 PR 0.2 - 0.3 678 420 0 0 0.04 0.09 0.06 0 0 0 8 2 0 354 0 17 PR 0.3 - 0.5 463 321 0 0 0.04 0.07 0.06 0 0 0 7 2 0 248 2 13 PR 0.5 - 1 391 267 0 0 0.05 0.05 0.04 0 0 0 8 2 0 212 4 19 PR 1 - 2 319 303 1.0 0 0.04 0.04 0.05 0 0 0 4 2 0 198 2 8 PC 0.063 - 0.2 993 327 4.5 0 0.08 1.15 0 0 0 0 4 2 0 119 4 62 PC 0.2 - 0.3 887 315 0 0 0.06 1.17 0 0 0 0 2 2 0 105 2 56 PC 0.3 - 0.5 662 253 11.4 0 0.06 0.88 0 0 0 0 2 2 0 74 2 46 PC 0.5 - 1 547 236 3.0 8 0.08 0.95 0 0 0 0 38 2 0 75 59 32 PC 1 - 2 428 173 3.9 0 0.04 0.36 0 0 0 0 0 0 0 31 0 34 TO 0.063 - 0.2 1170 756 0 0 0.09 5.31 0.11 0 0 11 57 4 0 306 19 15 TO 0.2 - 0.3 855 677 0 0 0.08 4.08 0.06 0 0 6 44 6 0 229 17 11 TO 0.3 - 0.5 632 457 0 0 0.07 3.36 0 0 0 6 42 6 0 219 33 13 TO 0.5 - 1 574 438 4.6 0 0.07 3.39 0.07 0 0 4 40 8 0 171 15 13 TO 1 - 2 436 359 4.3 1 0.06 3.43 0.12 0 0 4 23 13 0 147 25 11 FE 0.063 - 0.2 1064 59 1.8 0 5.53 0.53 0 0 0 0 15 6 0 6 44 21 FE 0.2 - 0.3 807 30 3.4 0 4.52 0.39 0 0 0 0 15 4 0 4 33 19 FE 0.3 - 0.5 741 42 7.7 0 2.95 0.36 0 0 0 0 16 2 0 6 33 14 FE 0.5 - 1 584 20 3.4 0 1.80 0.30 0 0 0 0 17 2 0 4 36 15 FE 1 - 2 528 18 6.4 0 1.45 0.32 0 0 0 0 15 2 0 11 29 13 FC 0.063 - 0.2 1043 5 0 0 38.53 1.05 0 4 0 2 19 27 0 31 13 31 FC 0.2 - 0.3 919 15 4.6 0 37.32 0.89 0 2 0 2 17 15 0 27 13 20 FC 0.3 - 0.5 779 13 15.5 1 25.20 0.93 0 0 0 2 19 10 0 23 16 10 FC 0.5 - 1 695 45 5.1 4 12.50 0.88 0 0 0 2 21 8 0 37 55 14 FC 1 - 2 608 47 5.1 0 0.80 0.74 0 0 0 2 21 6 0 41 10 14 Table 3.2.1.3: leaching test results for elements subject to regulation for plants (d.lgs 156/2006). In red, concentrations exceeding legal limits. For instance, sulphate and Cr are above regulatory limits only in IREN BA, but Ba and Ni (with the exception of TO) only in the HERA plants. Sr leaching is observed in high percentages in FE and FC (10-15% of the bulk), and less in the IREN plants (4-6% in TO and 1-2% in PR and PC). A likely interpretation is that Cr could have a significant concentration in ettringite, which is dissolved in 79 IREN plants, whereas Ba, Ni and Sr could exchange with Ca in significant amount in portlandite, which is dissolver in HERA plants. Zn and Mg are released only in the TO and PR plants, possibly in relation with ettringite dissolution. In TO the leaching of SO4, Co, Cu, Mg and Zn is higher than in other plants, and in PC B and Mo show higher leaching. These differences, which are more than one order of magnitude look specific of an WtE, or at least of the analyzed sampling from that plant. Cu, Cr and Ni are, among the PTE, the most released in all plants with values below 0.5%, except for TO where the Cu stands at 3%. On the other hand, the release of Ti, Pb and Zn is relatively low (<0.01%), never exceeds law limits (Legislative Decree 152/06) suggesting their presence in a nonsoluble structure, like glass or silicate minerals. 4. Conclusions The bottom ashes from the WtE plants show an average composition remarkably similar in major elements, just with higher iron in TO, and lower Si/higher LOI in PC. The chemical composition of major and minor elements changes with grain size, but within an order of magnitude and similarly in the different plants. The similar BA composition could be related to a similar waste management approach in the area. The mineralogy is different between HERA (FE and FC) and IREN (TO, PR and PC) BA. In the former we have lower amorphous and higher portlandite and ettringite, in the latter we do not have portlandite and the amorphous phases are between 60 and 90%. This affects leaching, which occurs in different basic environment: the leachates show higher sulphate and Al in IREN plants, and lower sulphate-higher Ca in HERA plants. Leaching up to two orders of magnitude lower in Ba and Sr, and higher in Cr occurs in IREN. The balance of Cl leaching shows that alkaline chlorides account just for about 30-35% of the global Cl, a fraction which does not show significant changes with grain size and between WtE, and that is similar to the findings of Alam et al. (2020). Composition and leaching is for most elements size dependent, but almost invariably within an order of magnitude. Some elements like Cl, Zn, S, and the LOI decrease with grain size, but for other PTE like Ni, Cr, Co and Pb this is not a rule. Leaching increases in smaller grains for almost any element, but again within an order of magnitude, whereas between WtE plants we find higher variability in leaching efficiency. From a circular economy perspective, reuse of BA as a supplementary material in concrete is possible: the presence of cement related minerals such as portlandite in FE and FC supports reuse in the concrete, facilitating the setting and hardening reactions. However, significant concentrations of Cl and S, especially in the finer grain size, could be disadvantageous for cement application and a pre-treatment before application as cement bind could be envisaged. Grain sorting 80 could be useful in cases where leaching of the larger grain size falls below the legislative limits for a given element, while the smaller grains do not, like Cr in PC and Cu in PR. It could be more profitable to gain acquaintance with the mineralogical and chemical dissolution behavior of the BA from a given plant being the differences in the leaching of minor elements look more dependent to the mineralogy than to grain size. Author contributions LM, MT: conceptualization, methodology, data collection, data calculation, writing–original draft, and writing–review and editing. CDM, PP, ED, ST, VF, TB: methodology, data collection, data curation, editing. LM, MT, CDM, PP, ED, ST, VF, TB have read and agreed to the published version of the manuscript 81 3.3 PTE SPECIATION: COMBINED SEM-EDS ANALYSIS, XRF AND XANES BY SYNCHROTRON RADION STUDY The focus of this third work was PTE (Pb, Cu, Zn, Ni, Co and Cr). For this reason, BA sampled from the Parma waste-to-energy plant (0.5 - 1mm grain size class), was studied through a multi-technical approach. Previously, as shown in the first two papers, this particle size class was analysed by diffraction and fluorescence techniques to gain an overview of the chemistry and mineralogy of the material. Subsequently, some BA grains were analysed by SEM - EDS and XRF mapping and XANES analysis conducted by synchrotron facility. In this way, information was obtained regarding not only the mineralogical environment in which the PTE are housed but also their oxidation state, information of crucial importance in assessing the potential toxicity of the material under study. From the results obtained, it can be seen that the chemical elements analysed are present in different chemical forms, especially zinc, which turns out to be the element found in a greater variety of mineralogical phases but not in metallic form. Chromium has never been found in +VI oxidation state, its most toxic form. In general, PTE has been found in the form of metal (sheet or alloy), oxide (or hydroxides), carbonates, sulphates, silicates, or as substituted in other crystal structures or amorphous matrices. The results obtained are coming from an article that is in the process of being submitted. The article is reported as paragraph 3.3.1. For simplicity, figures and tables have been re-numbered following the structure of this thesis. 3.3.1 PTE speciation in Bottom Ashes from Municipal Solid Waste Incinerator: a combined SEM-EDS, XRF and XANES by synchrotron radiation study Authors: De Matteis C.1, Pollastri S.2, Mantovani L.1, Tribaudino M.3 1Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale (SCVSA), Università di Parma, 43124 Parma 2Elettra Sincrotrone Trieste S.C.p.A., 34149 Trieste 3Dipartimento di Scienze della Terra, Università di Torino, 10124 Torino Type: Article Journal: Science of Total Environment Status: Submitted 82 Abstract Potential Toxic Elements (PTE) in Municipal Solid Waste Incinerator Bottom Ash (MSWI-BA) may be toxic depending of their oxidation state and mineralogical environment. In this work, Cr, Ni, Pb, Co, Zn and Cu chemical speciation are investigated on BA from Parma Waste to Energy (WtE) plant by means of SEM-EDS, µ-XRF and XANES measurements by synchrotron radiation. This multitechnique approach allowed to examine PTE providing a general picture of mineralogical and chemical properties such as the oxidation state. SEM-EDS analyses show the presence of Zn and Pb in minerals and in glass matrix. Cr oxide and chromite has found whereas Cu and Co are present as metal inclusions or alloy. µ-XRF mapping reveals that Cu, Ni and Cr are generally together with Na, K and Si suggesting their presence in glass matrix. XANES spectra show that Cu has a variable oxidation state suggesting its presence as oxide, hydroxide, acetate and metal form. Zn is mainly in the +II oxidation state confirming the SEM-EDS data. Cr has been found always as +III, whereas the +VI oxidation state was never identified. Pb spectra have a good match with oxides. Ni and Co were found either as oxides and in metal form. Graphical abstract 83 Keywords BA-MSWI, PTE, Chemical-mineralogical characterization, XANES, speciation, leaching 1. Introduction A considerable input of anthropogenic material in the environment is given by waste. In 2016, world waste production was equal to 2.01 billion tons and due to economic and demographic growth will reach the 3.40 billion tons in 2050 (Kaza et al., 2018). The waste can be sent to recycling, composting, incineration processes or deposited in landfills. A considerable amount of waste, as much as 11% of the global production, is incinerated (Kaza et al., 2018). In industrialized countries, the incineration is entrusted to WtE plants, which recover energy as heat and/or electricity through controlled combustion of MSW. FA and BA are the main outputs of WtE processes. FA are classified as hazardous waste and constitute 4% of MSW mass, while BA are non-hazardous waste and represent 20% of MSW mass (Bertolini et al., 2004; Izquierdo et al., 2001; Nazionale, 2002). BA are formed by an extremely complex and heterogeneous mineral fraction. In recent years several studies aimed to characterize BA from a chemical, geochemical, mineralogical and physical point of view (Alam, Schollbach, van Hoek, et al., 2019; Assi et al., 2020; Bayuseno & Schmahl, 2010; Caviglia et al., 2019; Huber et al., 2020; Loginova et al., 2019; Mantovani et al., 2021). BA are made of silicates, carbonates, hydrated minerals, sulphates, phosphates, oxides and an amorphous component that in the larger particle size classes can be up to 80% - 90% of the global content (Alam, Schollbach, van Hoek, et al., 2019; Assi et al., 2020; Bayuseno & Schmahl, 2010; Caviglia et al., 2019; Inkaew et al., 2016). The major elements are Si, Ca, Al, Mg, Fe, K, S, P and Na whereas among the minor few potentially toxic elements (PTE) such as Pb, Cu, Cr, Zn and Ni are found (Alam, Schollbach, van Hoek, et al., 2019; Caviglia et al., 2019; Funari et al., 2015; Mantovani et al., 2021). With respect to the global Earth Crust composition, Dijkstra et al. (Dijkstra et al., 2019) showed an enrichment in Ca, S and P, and slightly less in Si. To note, PTE are strongly enriched respect to the Earth Crust. This poses a bias in re-using BA due to the possible release of PTE in environment. Several investigations on the leaching behaviour of BA were done, demonstrating that PTE release is major in finer grain size because of both the particle dimension and the great presence of watersoluble mineralogical phases such as ettringite and hydrocalumite (Alam, Schollbach, van Hoek, et al., 2019; Caviglia et al., 2019; Feng et al., 2007; Huber et al., 2020; Loginova et al., 2019; Mantovani et al., 2021; Šyc et al., 2020; Wei et al., 2017; Yao et al., 2012). 84 The mobility of an element towards an environmental matrix is strictly connected to chemical and mineralogical characteristics: PTE in silicates or glasses are released only after a strong acid attack, whereas PTE in soluble phases may be easily released in the environment. Therefore, several authors carried out sequential extractions to investigate the association between elements, crystalline or amorphous phases and their leaching behaviour (Abramov et al., 2018; Alam, Schollbach, van Hoek, et al., 2019; Goodarzi & Huggins, 2001; Haberl & Schuster, 2019; Zhu et al., 2018). However, due to the complexity of the material and the low concentration of PTE it is difficult not only to obtain an unambiguous correspondence between mineralogical and chemical information but also to analyse the PTE at a detailed scale, determining its concentration and oxidation state in the different phases. This information is crucial to predict and assess the potential release and toxicity, but also for a valuable reuse of BA (Rissler et al., 2020). Synchrotron-based XAS is one of the techniques that can be used to investigate the chemical speciation of elements. The main advantage of XAS is to determine the local atomic environment and oxidation state of a given element. It is a very sensitive method, able to investigate elements also in low concentration. In literature, there are few studies in the use of synchrotron-bases XAS for MSWI investigation. In details, the most part of the data focused on Cu and Zn speciation in FA (Hsiao et al., 2001, 2002, 2006), less on BA (Lassesson & Steenari, 2013; Rissler et al., 2020; Steenari & Norén, 2008; Tiberg et al., 2021) and no data are found on others critical elements like Pb, Cr and Ni. A limit in XAS methods regards the lack of analytical data on the other elements present in the same point. Therefore, the textural information, like crystal size, clustering, shape and/or inclusions of other phases in the areas of analysis is lost. This affects the reliability of the XAS analyses in showing the distribution of the different phases in the sample. Synchrotron radiation-based micro-XANES together with micro-XRF provides a powerful alternative. With a narrowly focused beam, sized as little as 50µm2, micro-XRF analysis shows the local composition, with a sensitivity down to the ppm for the minor elements. The distribution of the PTE can be revealed, and in chosen points the XANES analysis can be done, showing the local environment for specific elements. Micro-XRF and XANES were combined in environmental and cultural heritage studies, where an heterogeneous matrix is present (Kostomitsopoulou Marketou et al., 2021; Liu et al., 2020), but not in BA from incinerator yet. The novelty of the present study is to present for the first time the combined micro-XRF and XANES data on BA, with the aim to determine not only the chemical form and speciation of PTE, but also their textural distribution and association with other elements. SEM-EDS analyses have been performed on the same studied sample, as well. In respect with micro-XRF, the analytical resolution 91 Figure 3.3.1.2 SEM-BSE image of grains with PTE: a) Willemite-hardystonite assemblage (willemite white, hardistonite gray); b) ZnO (white), overgrowing non stoichiometric Zn bearing gehlenite (gray); c) Cu-Sn oxidized alloy (white); d) Zn-Mn oxide (white); on the left of the image we find Ca-carbonate, gray, and glass, dark gray; e) FeCrO3, white, coexisting in a composite grain with Ca-rich glass (light grey) and alumina (dark gray round phases); f) Ca-plumbate (Ca2PbO4), shown by white squared grains, together with lime (light gray), and silicate glass; g) Pb with TiO2 oxide (white rounded grains) ; h) glass matrix with Croxide inclusions (white points). 92 The embedded grains are generally made by a core, with the shape neatly appearing from the epoxide in BSE images. A rim usually borders the core, with smaller crystals embedded in a darker matrix. SEM-EDS analysis on the rims could be done just in few larger crystals, finding that they have a different composition from the core, i.e., among others, Ca-carbonate, phosphates, residual plagioclase, sulphates and chlorides. µ-XRF maps show that some elements, namely Ca and Si, but also Mg, Al, Fe, P, Cr, Ti, Co, and Pb are generally present within the core of the grains. Zn and Cu are found both in the rims and in the core, whereas others, like S and Cl and, to a lesser extent, Na and K, mostly at the rims. The different mineralogical composition between rim and the core grains suggests a formation of very small crystals of chloride and sulphate during weathering. Leaching tests on the same sample showed that Cl and S are the most leachable, supporting the hypothesis of their presence at the rim of the grains, and not within silicate glasses. Also, the core of the grains is heterogeneous: SEM-EDS observations at higher resolution indicate the coexistence of several crystals as silicates, oxides, carbonates, metals inclusions and glass (Figure 3.3.1.2). µ-XRF data show a more detailed distribution of the PTE than SEM-EDS results: this is expected, as PTE are generally below SEM-EDS analytical resolution. However, in few cases when the µ-XRF indicates a higher concentration of a given element, it is not possible to find a counterpart in the SEM-EDS maps. Although the two methods analyse the same areas, the detected volume is different: in µ-XRF the beam probes a depth of few tens of microns, whereas the SEM-EDS probes 1-2 µm maximum. The PTE rich phase may not be present at the surface of the grain, so to be revealed by SEM-EDS, but just few microns below, and detected instead by µ-XRF. Due to the spatial resolution of acquired µ-XRF maps, lower than that of SEM-EDS, and the heterogeneous nature of BA, a given µ-XRF analytical pixel may sample a number of different phases. Throughout the overlaps of single elements µ-XRF maps, the distribution of PTE was analysed and associated to major elements (Si, Ca, Mg, Na, etc) obtaining the mineralogical environment in which PTE are incorporated. Among the PTE, Cu is present generally together with Na, K and Si, in glass morphologies observed with SEM-EDS. To note, in the same areas EDS analysis do not revealed the presence of Cu-bearing phases, indicating that Cu is below the instrumental resolution or in tiny grains under the surface. Cu was found in one grain as a Cu-Sn alloy also with Ni; Cu was also found as alloy/metal inclusions and droplets dispersed within the glass as observed by Mantovani et al. (Mantovani et al., 2021). In a grain, Ni occurs in alloys with Co and Mn, and with Co and Cr. Generally, however, Ni appears together with Fe and Cr, in a phase that was confirmed as chromite by XANES analysis, and, most 93 frequently, together with Na, K, Si and Al in an assemblage likely a glass. To note, Ni was not found together with S and Cl. Co was found together with Ni, likely in alloy; overlap with O indicates some degree of oxidation. In the same grain, an overlap of Co and Cl might indicate formation of chlorides. Cr is generally associated with Fe, but also with Si, Ca, Fe, Na and K. The suggestion is that it is dissolved in a glass, or in tiny chromite crystals. Cr was not present together with S and Cl. Pb is found most in larger grains, in the core and in the rims of the grains. It is associated with Ca and Zn, but not with Si. This could suggest a carbonate phase. Pb occurs with S in few grains, where S is present within the core. This is not unlikely, in view of the strong affinity of Pb for sulphides. Pb is also found with Si, Na, K and Mg in Pb-rich glass. Zn is found in core as trace in amorphous material and in rims, together with S and Cl suggesting their presence in sulphates and chlorides and together with Ti, in spinel-like structure. 3.4 XANES A major advantage of XAS is to be element specific, modelling the X-ray Absorption Edge of a given electron transition for a given atomic species. It provides information on the local environment and oxidation state of the considered element, but it does not provide a chemical information of the specific phase where the element is present. As the element may be in different oxidation states and different phases within the area sampled by the beam, a deconvolution of the different contributions is often necessary. Comparing XANES results with those from SEM-EDS and µ-XRF analysis, the disadvantage of not having the composition of the emitting phase, is compensated by the sensitivity of the XANES emission, able to probe an element at few ppm concentrations and within submicrometric phases. Oxidation state and possible host phases for each of the PTE are here reported. Cobalt XANES spectra were recorded at the Co K-edge in one clast, on which higher resolution SEM-EDS analysis showed that the grain is made by a partially oxidized Co-Mn alloy, mingled with Al2O3 and a Ca-silicate phase (Figure 3.3.1.3). XANES results confirm that Co is present in a partially oxidized alloy: LCF analysis indicates that Co is present at 68(7)% in the form of metal Co and at 32(4)% as Co-oxide. In the same grain, a single XRF spectrum extracted from the map highlight the presence of also Ni, present below the analytical resolution of SEM-EDS. A XANES spectrum collected at the Ni K-edge (labelled as Ni3_1). indicates that also Ni is present as a partially oxidized alloy: LCF results shows indeed that 94 metal Ni [84(5)%] coexists with divalent Ni-oxide [16(20)%]. Hereafter, the label of the spectra will be reported as Xa_b where X is the element, a is the area and b the point analysed. (APPENDIX XVI). Figure 3.3.1.3 Co-bearing grain. a) Image of the grain taken with the microcamera available at the XRF beamline; b) SEM-BSE image on the same area with a three phases assemblage: metal cobalt (white), oxidized area with Co/Mn ratio 2/1 (gray) and mixture of alumina and Ca-Al silicate (black); c) XRF spectrum representative of the clast, with label of the main fluorescence lines; d) Normalized XANES spectrum collected on the same grain at the Co K-edge. Copper XANES spectra collected at the Cu K-edge in different clasts are reported in Figure 3.3.1.4. LCF analysis (Table 3.3.1.3) suggests that Cu chemical environment and oxidation state are heterogeneous even in the same area, ranging from metallic to Cu +II. Three spectra (Cu1_1, Cu2_1 and Cu2_2) have a broad white line peak at about 8997 eV, together with a minor pre-edge peaks at about 8981 and 8985 eV, respectively. They fit with divalent Cuoxide , but the contribution of monovalent Cu-oxide, and, in one spectrum, of residual metal, are necessary to obtain the best fit. In another grain (Cu3_1) we find a doublet at 8994 and 8998 eV, possibly indicating the presence of cupric acetate. SEM-EDS analysis on the same areas did not show phases with sufficient enrichment in Cu to show significant emission in Cu-Kα peaks. It is possible that Cu in the areas is below the analytical 95 resolution of SEM-EDS, i.e. few thousands of ppm, but it could be also an effect of the different sampling size of SEM-EDS and XANES analyses. Only in one case Cu was found by SEM-EDS analysis as well, in a Cu-Ni-Sn alloy (Figure 3.3.1.2 c). Figure 3.3.1.4 Normalized Cu XANES spectra of reference materials (top) and collected on various clasts of the BA samples (bottom). Compounds Cu1 1 Cu2_1 Cu2_2 Cu3_1 Cu_T Metal Cu 10 (4) 80 (3) Cu2O 6 (4) 24 (5) 13 (4) 16 (4) CuO 94 (2) 66 (3) 87 (3) 4 (2) Cu(OH)2 11 (6) Cu(CH3COO)2 89 (6) Table 3.3.1.3 Results of the LCF analysis performed on the spectra collected at the Cu K-edge on BA clasts (reported quantities are %; sigmas in brackets). 96 In this grain, XANES spectrum fits with metal Cu (Cu_T in Figure 3.3.1.4), showing the typical triplet at 8981, 8994 and 9004 eV, and indeed confirmed by LCF results. The Cu speciation in BA showed that Cu is present in different oxidation states (0, +I and +II); this was also observed by Rissler et al. (Rissler et al., 2020), and interpreted as an effect of zones in the fuel bed with different access to the oxygen. Here, however, we observe coexistence of different oxidation states within the same grain. Zinc Zn was found in BA in a number of different phases, some of them well visible also in SEM-EDS. Various XANES spectra (12 in total) at the Zn K-edge were collected on different clasts; a selection of the most representative ones is reported in APPENDIX XI where is visible that the edge position of all the spectra is similar and shifted with respect to reference Zn foil, indicating that Zn is not present as a metal but mainly occurred in oxidation state +II (Table 3.3.1.4). Clast Zn2_3 is the only one to have a weak pre-edge, whereas two peaks at about 9665.3 and 9667.9 eV are clearly distinguishable in all the spectra except that of clast Zn1_2, which has only one peak at about 9666.5 eV. The LCF proved difficult because of the heterogeneity of the collected spectra. In all the spectra, a great fit is obtained with Zn-carbonate, in the form of smithsonite (ZnCO3) or hydrozincite (Zn5(CO3)2(OH)6). Smithsonite is here first observed, but Zn in solid solution within carbonate was reported by Piantone et al. (Piantone et al., 2004b) in an investigation on weathering phases. Hydrozincite was found by Rissler et al. (Rissler et al., 2020) and dubiously by EXAFS analysis by Tiberg et al. (Tiberg et al., 2021). Zincite (ZnO) was found in few grains, confirming SEM-EDS results and previous XAS data by Rissler et al. (Rissler et al., 2020) and Tiberg et al. (Tiberg et al., 2021). Compounds Zn1_1 Zn1_2 Zn1_3 Zn2_1 Zn2_2 Zn2_3 Zn3_1 Zn3_3 Zn3_4 Zn3_5 Zn3_6 ZnT ZnO 29 (6) 32 (5) 36 (6) 28 (6) ZnS 27 (3) 51 (3) 33 (3) 54 (2) 62 (2) 51 (2) ZnCO3 15 (2) 45 (7) 39 (4) 44 (3) 28 (4) 21 (5) 64 (6) ZnAl2O4 34 (3) Zn4Si2O7(OH)2· (H2O) 41 (6) 17 (3) 9 (3) 24 (5) Zn3(PO4)2 42 (4) 41 (5) 27 (10) ZnFe2O4 34 (7) 43 (4) Zn5(CO3)2(OH)6 31 (5) 34 (0.9) 26 (1) 22 (4) 29 (4) 29 (4) 26 (2) ZnCl2 26 (10) 8 (2) Table 3.3.1.4 Results of the LCF analysis performed on the spectra collected at the Zn K-edge on BA clasts (reported quantities are %; sigmas in brackets). 97 Due to the similarity of the XANES spectra of zincite and Zn-hydroxide, Zn(OH)2 could be also present. In five of the examined spectra the fit required the ZnS phase in substantial amount. The phase is here first observed, and could be present by reduction of sulphates during weathering. The presence of Zn-phosphate is not surprising, as several Zn phosphate phases were found by (Piantone et al., 2004b). However, Zn-phosphate was not found by Rissler et al. (Rissler et al., 2020). Also, spinel phases like gahnite and Zn-ferrite (ZnFe2O4) are present, as well as the silicate hemimorphite [Zn4Si2O7(OH)2·H2O]. Both are common findings in Rissler et al. (Rissler et al., 2020), and Tiberg et al. (Tiberg et al., 2021). However, a possible misinterpretation can be done due to the absence of a standard for Zn in silicate glass, where it was found here and in Mantovani et al. (Mantovani et al., 2021) (Table 3.3.1.5 2). Last, the ZnCl2 was found only in one spectrum (Zn2_1); this compound was found mainly in FA (Cai et al., 2015; Kitamura et al., 2020) but also in BA where its presence can be explained by the encapsulation of chloride within sintered BA particles (Rissler et al., 2020). It is possible that Zn is dispersed in small quantities, but being a highly soluble salt, its presence poses environmental concern. Chromium The LCF analysis results showed that three of the four collected spectra (Cr1_1, Cr2_1, Cr2_2) fit mainly with FeCr2O4, with a percentage ranging from 60-77% (APPENDIX XIV and Figure 3.3.1.5). In the spectra Cr1_1 and Cr2_1 was also found metal Cr (23% and 27%, respectively) and 40% of Cr2O3 in Cr2_2. In one spectrum (Cr3_1) metal Cr (24%) and Cr2O3 (76%) were found, in agreement with SEM-EDS analytical results of chromium-aluminium oxide (Cr1.81Al0.19O3). In all XANES spectra Cr was present in the Cr 0 and Cr III+ oxidation state. No evidence of Cr VI+, which would show the typical high intensity pre-edge peak at about 5993 eV, was found. Lead Several XANES spectra at the Pb L3-edge were collected, which show the same features and are almost identical: a very broad white line peak at 13052 eV is invariably present (APPENDIX XII). From the comparison of the edge position with respect to Pb metal foil and Pb oxide standard compound spectra, Pb is expected to be oxidized in all the clasts. The LCF analysis results showed fits with PbCO3 (29-43%) and Pb3O4 (57-71%) (APPENDIX XV). In these compounds, Pb is present in +II and +III chemical forms. Other reference compounds, like PbO, PbO2, and PbCl2 were tested, but none gave a satisfactory fitting. Also, in the same areas, S fluorescence lines were not detected, which discarded PbS and PbSO4 as possible candidates. As for Zn, we did not try to fit Pb in a glassy environment, so we cannot rule out the presence of Pb in an alkali rich silicate glass, which could be 98 compatible with the chemical composition of some of the investigated clasts (from XRF data). XANES spectra of Pb in PbO-Ga2O3 glasses show, similarly to our sample, a single broad white line peak, which is also similar to the XANES spectrum of Pb in a silicate structure (Choi et al., 1999; Dubrail et al., 2009). Nickel Like Cu, Ni is found in SEM-EDS only in the above described grain together with Co, and is revealed just by XRF. The XANES spectra at the Ni K-edge (APPENDIX XIII) were compared with Ni metal foil, NiO and Ni(OH)2. LCF analysis shows that Ni, like Cu and Co, is present in metal and oxidized form, but hydration is also possible. The results of LCF analysis (APPENDIX XVI) indicate that the metal is always partially oxidized and hydrated. Figure 3.3.1.5 Normalized Cr XANES spectra of reference materials (top) and collected on various clasts of the BA samples (bottom). 4. DISCUSSION The fate of PTE In previous investigations on the speciation of PTE, several potential host minerals were suggested [11, 23, 56, 27, 29, 50–55]. This investigation confirmed the previous results, and possibly widened somehow the list (Table 3.3.1.5.1, 3.3.1.5.2, 3.3.1.5.3). However, being silicate glasses the major 99 phases of BA, a significant speciation in the glassy phases can be expected. In BA, where local equilibria are a rule, we may find glasses with different composition, although generally enriched in alkalies (Mantovani et al., 2021), able to host the different atomic species in their structure. The glass formed by the high temperature of the combustion chamber is easily detected in BSE images: it is present in the core of the grains, it embeds the crystals, and shows a composition of a Ca-Al silicate enriched in alkalies. The same compositional pattern was shown by XRF, in areas where SEM-BSE images showed a glass. SEM-EDS analyses on the glass in the core found in few grains Zn, Cr or Pb just above detection limits, although evidence of PTE in silicate glasses was not confirmed by XANES. In BA several glassy phases coexist with different composition likely hosting PTE. Because of the lack of reference standards for glass, XANES spectra might miss the contribution of PTE present in glasses. Mingling with crystalline phases, and with a non-definite chemical composition, the characterization of this heterogeneous matrix is rather complex task. Even combining µ-XRF and SEM-EDS analysis, only in few grains distinct phases hosting the investigated PTE can be detected. In previous investigations [23, 29], without the use of µ-XRF, the XAS spectra were always interpreted with crystalline phases standards, overlooking possible contribution of the glass. Bearing this in mind we may suggest a possible speciation for each of the PTE. Cu is found in different oxidation states. It was mainly found in metal forms, pure or as an alloy, which is partially oxidized as Cu I+ and Cu II+. It was observed as tiny droplets in the silicate glasses. This work and Rissler et al. (Rissler et al., 2020) suggest that it may also undergo weathering as a hydroxide or a chloride. Co is mostly present as an alloy, where found, with Mn, Ni or Fe, and only partially oxidized to Co II+. XRF shows that Pb, differently from Cu, is distributed mainly in larger grains, both in the core and in the rim, host in glasses and carbonate minerals in agreement with the XANES results. Besides, in SEM investigation, Pb was also found as a Ca-plumbate phase possibly formed by Pb-rich glass and lime. In a previous studies on the speciation of Pb in FA, it was found as metal Pb, PbCl2, PbO and PbCO3 (Zhu et al., 2018). Cr in higher concentration is generally found as an oxide, like spinel chromite or an Al-Fe-Cr oxide. In lower concentration, Cr occurs in glasses. No evidence of Cr VI+ or correlation with sulphate was detected. Ni is present as a metal or in spinel solid solution together with Cr and Fe. However, it looks more prone to alteration than Cr, forming Ni-bearing oxides and hydroxides. Last, Zn is present in a number of phases, some of them probed by SEM-EDS, others mingled within a single 50x50µm2 area, identified by XANES spectral deconvolution. Zn is observed in silicates like willemite, hardystonite or hemimorphite, in oxides and hydroxides, like gahnite spinel and zincite, in ZnS, in the very soluble form of ZnCl2 and in carbonates like smithsonite or hydrozincite that can be 100 an alteration product of hemimorphite. Moreover, the presence of Zn in a silicate glass is suggested by a locally enrichment revealed by SEM-EDS. It was not found in sulphates or as a metal. In Tables 5.1, 5.2, 5.3 a list of the minerals containing the investigated PTE in BA in this work and previous investigations is reported. PTE were found in two mineralogical occurrences, like it was here observed: as minor components in silicates, metals, oxides and hydroxides, including glassy phases, or as phases in their own, as an effect of their local concentration. A further difference is in phases present as tiny inclusions, well below 1 µm, which could be revealed just by XAS or TEM, or, when in significant amount, by XRD. An example is the Cu oxides inclusions, i.e. tenorite and cuprite, which are likely present for oxidation of metal Cu, or that of ZnCl2 and hemimorphite, observed only by XANES in this work and in Rissler et al. (Rissler et al., 2020). The nanoscopic minerals show higher surface and different size-related properties which should be taken care in any geochemical modelling (Hochella et al., 2019). The presence of PTE in submicrometric crystals or glasses was revealed by the XRF mapping, showing significant concentration of them, in areas where they were not found within single phases by SEM. Moreover, in the enclosed list, several minerals appear just in one single paper, like Zn2P2O7, Zn3(PO4)2 · 4H2O or Zn2PO4(OH). These phases were identified by XRD, assumingly in significant amount, but they didn’t find by other authors. In Meima and Comans (Meima & Comans, 1999) as much as 26% of the examined particles were containing Zn in metal form, while here in none of the investigated samples it was found. Likewise, it was observed for Pb. This indicates that each WtE plant has its own mineralogy, and that for any use of the BA, a specific investigation should be done. However, from the list it appears that comparing with different WtE plants, we can see that PTE are found in some common mineralogic phases. For Cu the commonly observed is in metal Cu, which is more or less altered as Cu I+ or Cu II+ oxides or Cu(OH)2. The carbonate form, commonly observed in alteration of mining deposits, is less reported. In few cases it may enter in the complex spinel oxide structure. Cu associated in silicates did not find in this work, but this was reported by Rissler at al. (Rissler et al., 2020) and Meima and Comans (Meima & Comans, 1999). If present, Cu-silicates together with metal Cu are probably combustion products, while the others are related to subsequent weathering. Zn is found in a wealth of different phases. As a high temperature Zn dominant phase, zincite is the main mineral, but also silicate willemite and the spinels franklinite and gahnite are commonly found. Zn-phosphates and metal Zn are also found, but not in this investigation. Zn is also present as an impurity in other oxides, in silicate glasses, in feldspars and pyroxenes. The alteration products are silicate hydrated, hydroxides, carbonates and chlorides. All of them have been observed by XAS, indicating their presence as nanosized grains. Such rather complex mineralogy of Zn produces an 107 Figure 3.4.1: XRD pattern collected for Piacenza samples (PC) and 0.063 – 0.2 samples Parma (PR) for each extraction. 108 Alam et al., 2021 ≤ 0.125mm Alam et al., 2021 0.125 - 1 mm PC 0.2-0.3 mm PR 0.063 - 0.2 mm PR 0.3-0.5 mm PR 2 - 4 mm PR < 4 mm Mineral Chemical formula S0 S1 S2 S3 S4 S0 S1 S2 S3 S4 S0 S1 S2 S3 S4 S5 S0 S1 S2 S3 S4 S0 S1 S2 S3 S4 S0 S1 S2 S3 S4 S0 S1 S2 S3 S4 halite NaCl x x x x x x x gypsum CaSO4 · 2H2O x x ettringite Ca6Al2(SO4)3(OH)12 · 26H2O x x hydrocalumite Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O x x x x x x x x x x portlandite Ca(OH)2 x x x zeolite X(AlO2)n(SiO2)1-n · mH2O x x calcite CaCO3 x x x x x x x x x x x x x apatite Ca5(PO4)3(Cl/F/OH) x x x x x x x x x x x x x x x x x x x anydrite CaSO4 x x x x x larnite Ca2SiO4 x x x x spinel XY2O4 x x x x x x x x x magnetite Fe2+Fe3+2O4 x x x x x x x x x x x x hematite Fe2O3 x x x x x x x x x x x x x x x x x x x x x x x rutile TiO2 x x x x x x x x x x x x x x x x x x x x x x x x x x x corundum Al2O3 x x x x x x Cu-Ti oxide x Pb-Fe oxide x wustite FeO x x x x x muscovite KAl2(AlSi3O10)(OH)2 x x x x x melilite (Ca, Na)2(Mg, Fe, Al, Si)3O7 x x x x x x x x x x x x x x x x x x x x x x x plagioclase (Ca,Na)[Al(Al,Si)Si2O8] x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x pyroxene ABSi2O6 x x x x x x x x x x x x x x x x x x x x quartz SiO2 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x Table 3.4.1: mineralogical phases found (x) after each extraction in Alam et al. (2019), Piacenza BA and Parma BA 109 XRD analyses were performed at the end of each step, and the results obtained were compared with those reported by Alam et al., 2019. X-ray diffraction (Table 3.4.1) showed that after the first step halite is removed in all samples; ettringite, present in Piacenza and found by Alam et al. (2019), and portlandite, present only in Parma samples, are removed after treatment with ultrapure water. After the second step calcite and hydrocalumite are no more present in all samples. Melilite is partially removed in Alam et al., 2019, in this work Piacenza sample and in the 2 - 4 mm and bulk ≤4 mm Parma samples. The dissolution of melilite is complete in 0.063 - 0.2mm and 0.3 - 0.5mm Parma grain size melilite. After the acid attack, new mineralogical phases are identified, no more overlapped by the removed phases. In the Piacenza sample and in Parma smaller grain size (0.063-0.2mm and 0.3-0.5) hematite, magnetite and rutile are identified. In the Piacenza sample Cu-Ti and Pb-Fe oxides were also identified, but were not found after the extraction occurred in the third step. After the third step melilite residual is totally removed and in Piacenza sample appears corundum. In the fourth step plagioclase intensity decreases, indicating the onset of a dissolution, and there are no significant changes from the previous residue. Only the Piacenza samples were undergoing to the fifth step and, after attack with HF and HClO4, only quartz, rutile and corundum are present. Figure 3.4.2 Weight loss in progressive extacted fraction. Green areas corresponding at first step (S1); yellow areas corresponding at second step (S2); red ares corresponding at third step (S3); blue areas corresponding at fourth step (S4); grey ares corresponding at residues 110 In APPENDIX XVII the results of the XRF analyses of the bulk samples at the different steps are reported. These results are averaged to 100% of the residue; to obtain the residual amount of each oxide (for major elements), and atomic concentration (for minor elements), the analytical value was recalculated by multiplying the analytical value with the ratio between the residual value and the one before the SEP. Moreover, the concentrations obtained from the four grain size in the SEP from Parma WtE were averaged. As shown in figure 3.4.2.3 we have for some elements like Cr and Fe, and, to a minor amount Ni, that the corrected value does not show a decreasing value, i.e, the element stays in the residual portion, at least within the experimental uncertainty. Other elements, like S and Zn do show a strong dissolution during the steps. Figure 3.4.3 Sequential extraction of major (a) and minor (b) elements. Green areas corresponding at first step (S1); yellow areas corresponding at second step (S2); red ares corresponding at third step (S3); blue areas corresponding at fourth step (S4); grey ares corresponding at residues The average of each element residual after the different steps from the four fractions was used to obtain Figure 3.4.3. The fraction extracted after each step is outlined for the major and minor elements. Although with the uncertainties related to possible sample in homogeneities, we find that Ba, Cr and Fe are almost completely in the residuals, whereas Pb, Zn, LOI, S, Ca and Sr do show a strong decrease after the acid etching. In the first step Br is almost completely extracted, and Na and K show a significant decrease, suggesting that they are present in a highly soluble phase, like chlorides. This is observed for any grain size, whereas Zn and S (Figure 3.4.4) content decrease in the first step only in the smaller grain size, and for Pb the decrease is just observed in one grain size. A strong decrease of the residual in the reducing stage is observed mainly for Cu, indicating possible reduction of hydroxides and oxides to metal. 111 Figure 3.4.4: Elements (mg/kg) in solid residues from XRF data At the end of step 4, some elements are almost completely leached, like S, Zn, Sr, Pb and Ca, indicating that they are not concentrated in resistant oxides, like spinels or in silicate crystals or glass. Still, for these elements a significant concentration of the element is present in the residual, likely indicating their presence in a silicate phase, as willemite or Zn-rich glass, for Zn, or in solution in feldspars for Sr (Tribaudino et al., 2005) Other elements like Cr and Ba are concentrated in the residual. For Cr this confirms its concentration in non-soluble oxides, whereas for Ba the suggestion is that the element is present in silicates, possibly in feldspars. It is not clear whether Ni has some significant leaching. 112 4 CONCLUSIONS The mineralogy, chemical composition and properties of the BA in five incinerators in Northern Italy were examined. The average composition, and the changes of the composition with grain size follow quite similar trends in all the incinerators. As shown in Figure 3.2.1.3 of chapter 3.2 the major and minor elements compositions are very close, and are well grouped in the compositional variation of the incinerators worldwide. This may indicate that, in spite of the different numbers of waste input between municipal and special waste, the input is comparable, at least in the unburned fraction. On the other side, as shown in Figure 3.2.1.6 in chapter 3.2 there are orders of magnitude in the leached fraction between the different incinerators, with higher differences between the incinerators of Ferrara and Forlì-Cesena, and the others. The difference is related to the mineralogical composition, and to where a given element occurs in a more soluble phase, and affects also whether the ashes are beyond legislation limits, as shown in chapter 3.4. The presence of portlandite in Ferrara and Forlì-Cesena buffers the pH to higher values, to stabilise ettringite, which does not dissolve with sulphates. The quantitative mineralogical differences (amorphous, carbonates) found between the WtE plants of IREN and HERA groups could be related to different burning temperatures, operating procedures or weathering conditions, and make an example on how the mineralogy may affect the properties of the ashes. The combined SEM-EDS, XRF-XANES, XRD analyses on different grain size and different grains enabled to find a number of new mineral hosts of the PTE (Co, Zn, Ni, Cu, Pb, Cr), found in metallic inclusions, oxides, carbonates, and amorphous matrices. As such combined investigation was not previously done, we may assume that the mineralogical variety which has since now been determined in BA, already represented by a considerable number of phases, is just a fraction of the actual one. As long as SEM-EDS is used on single grains, we observe that each grain shows chemically different bulk composition, and mineralogical assemblages. Just for an example Zn was found in BA in 27 mineral phases, of which 15 were confirmed or discovered in this work. Also, what is generally and simply described as an amorphous or glassy phase, is in fact a number of different phases, each of them in local equilibrium with the embedded crystals. This makes the prediction of the leaching behaviour of the ashes a risky task: the leached fraction for PTE is just a very small fraction, between 10-3 and 10-6 of the global content of the element, and a slight change in mineralogy, hardly or not detectable by XRD, may have a profound effect on the leaching of the samples. The precipitation of a small amount of a highly soluble phase containing PTE may increase dramatically the leached fraction. 113 We observed that the mineral fraction of BA is extremely heterogeneous, being made by slags, glass, metallic components, each of them chemically and mineralogically heterogeneous; chemical and mineralogical compositional differences were observed as a function of grain size, among different slags and within a single grain. This comes from a combined effect of the heterogeneous input, but also of the temperature gradients in the combustion chamber, promoting different equilibria at the different temperatures, and, last but not least, by the different weathering conditions, like position in the pile, moisture, different exposure time. There are however some regular features in the compositional relations between the elements, which could be outlined by the analysis of different portions of the same sample, sorted by grain size. Two opposite trends are observed: one shown by Si and grain size, the other, opposite correlated to the first, is shown by Ca, Cl, S and the residual loss on ignition. The first trend is followed also by some more lithophile elements, like Zr and Rb, the latter likely present in feldspar or silicate glass. The second trend is followed by PTE elements like Cu and Zn, but with some exceptions: in the WtE from Piacenza Zn does not follow a specific trend, and in the Forlì-Cesena plant, Cu follows the Si trend. Pb, Ni and Cr do not follow neither trend, with the exception of the Ferrara WtE, where Pb goes with S. It appears that Cu and Zn are hosted in carbonate, sulphate or chlorides in the different grain size, whereas Pb, Ni, Co and Cr may have different host minerals in the different compositions. As for the leaching behaviour it is generally observed that leaching increases as the grain size decreases, for Cl , Na (and K) and Cu, but other elements, like Cr and Ni follow a different trend in the WtE plants of Torino, Piacenza and Parma, where they follow the trend of Cl and Na, respect to Ferrara and ForlìCesena, where they seem unrelated to the grain size. This again, highlights the difference between the different plants. For a possible recycle of the BA, the results in leaching tests indicate that all the grain size below 2 mm, from any incinerator are beyond legal limits for some element. Chlorine and Cu are always beyond legal limits, and again we find a difference between incinerators: Ba, Ni, F are above limits in the Ferrara and Forlì-Cesena plants, SO42and Cr for the other incinerators. Ni and Other elements, like Pb and Zn were always leached below limits, although in Ferrara the Pb leaching is close to the critical value. Therefore, to make any use other than as insulator fillers, some kind of treatment is needed. The observation that PTE decrease with increasing grain size, is not always correct, and for Cu and Cl, in the examined grain size the leaching is so high that it is not expectable that simply sieving the larger portion will solve the issue. However, the larger grain size could be easier to wash, and the reactivity in the grains could be slower: our SEP showed that the leached fraction, no matter its toxicity, is higher in finer grains. The highly reactive nature of the ashes can be used as an aggregate in cement, 114 most for highly maturated material where cement minerals are present. Concrete obtained using BA as aggregate could fix the PTE in a structure where leaching occurs less. By this respect an investigation on the performance and on the leaching of concrete, obtained using ashes of different grain size as aggregates in concrete, before and after washing could be promising. Also, in light of the observed differences in the mineralogy of the different incinerators, we may expect different performances in concrete using ashes from different plants. Preliminary washing at some pH value should be useful, as our observation showed that most of the coarser grains do show a rim, made by smaller grains, and likely the more reactive part. The washing should be made as to disaggregate the rim portion, whose sewage could be subject of further recovery of metals. Finally, a note on the analysis of the ashes, considering as a geological material: generally speaking, BA are on average a material which can be chemically described within the CaO-Al2O3-SiO2 system, not far from the composition of basaltic rocks. The main difference is that the average composition comes from an average of micro or submicrometric equilibria, occurring within each grain. Equilibrium is not always achieved, and weathering plays a major role. To predict the thermodynamic behaviour would require preliminary homogenization, which is not economically feasible, and therefore the predictions on the fate of the incinerated material are a risky task. 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Energy Information Administration, Biomass Explained – Waste-to-Energy (Municipal Solid Waste), https://www.eia.gov/energyexplained/biomass/waste-to-energy-in-depth.php , consulted in 25/10/2022. Wikimedia Commons, https://commons.wikimedia.org/wiki/File:XANES_spectrum_Fe_XAS_Carpenter_2010.png , consulted in 30/11/2022. 128 APPENDIX I Linear Pearson’s r (lower triangle) and Spearman’s p rank correlation (upper triangle) for evaluating correlation grade between elements and the grain size (log10) for a) this work and for those of b) Caviglia et al. (2019) and c) Loginova et al. (2019). Correlation table for < 2mm grain size with major elements are also reported (d) . Pearson’s r represents the linear correlation. r = 0 no correlation. r = 1 completely correlated. while Spearman’s rank is significant (correlated) if p < 0.05. a) Data from this work Log(10) size Si Ca Fe Al Na Mg Ti K P Mn LOI S Cr Cu Ni Zn Pb Sr Cl Ba Zr Rb Log(10) size 0.000 0.000 0.107 0.518 0.007 0.072 0.017 0.189 0.185 0.627 0.000 0.000 0.535 0.005 0.786 0.000 0.277 0.094 0.000 0.003 0.000 0.000 Si 0.954 - 0.000 0.207 0.628 0.001 0.063 0.003 0.306 0.077 0.582 0.000 0.000 0.470 0.014 0.976 0.003 0.362 0.067 0.000 0.002 0.000 0.000 Ca -0.936 -0.992 - 0.152 0.484 0.002 0.030 0.008 0.214 0.117 0.639 0.000 0.000 0.479 0.016 0.902 0.004 0.378 0.079 0.000 0.006 0.682 0.072 Fe 0.541 0.437 -0.489 - 0.003 0.974 0.003 0.781 0.000 0.345 0.372 0.058 0.096 0.745 0.190 0.580 0.042 0.100 0.670 0.281 0.702 0.079 0.063 Al 0.233 0.175 -0.251 0.822 - 0.470 0.004 0.299 0.003 0.050 0.447 0.267 0.337 0.264 0.738 0.966 0.292 0.308 0.299 0.785 0.463 0.890 0.030 Na 0.786 0.881 -0.846 -0.012 -0.259 - 0.553 0.000 0.831 0.004 0.281 0.011 0.009 0.148 0.062 0.819 0.062 0.984 0.036 0.000 0.000 0.720 0.654 Mg 0.591 0.606 -0.680 0.831 0.821 0.214 - 0.714 0.001 0.603 0.996 0.013 0.019 0.603 0.278 0.448 0.094 0.157 0.855 0.098 0.604 0.250 0.894 Ti -0.729 -0.828 0.777 0.101 0.365 -0.958 -0.133 - 0.701 0.001 0.270 0.029 0.018 0.351 0.071 0.967 0.126 0.682 0.043 0.001 0.000 0.228 0.005 K 0.452 0.360 -0.431 0.914 0.826 -0.078 0.891 0.139 - 0.243 0.838 0.107 0.176 0.473 0.330 0.378 0.172 0.079 0.921 0.370 0.889 0.051 0.042 P -0.456 -0.583 0.528 0.335 0.631 -0.819 0.188 0.888 0.407 - 0.655 0.267 0.170 0.283 0.131 0.985 0.402 0.890 0.013 0.051 0.004 0.505 0.052 Mn -0.176 -0.199 0.170 0.317 0.272 -0.378 0.002 0.386 0.075 0.162 - 0.713 0.866 0.743 0.568 0.685 0.651 0.720 0.986 0.505 0.564 0.000 0.434 LOI -0.957 -0.973 0.979 -0.616 -0.389 -0.757 -0.748 0.685 -0.540 0.389 0.134 - 0.000 0.654 0.017 0.938 0.001 0.250 0.151 0.000 0.014 0.000 0.009 S -0.918 -0.973 0.980 -0.554 -0.339 -0.772 -0.721 0.723 -0.465 0.470 0.061 0.981 - 0.744 0.023 0.878 0.003 0.228 0.136 0.000 0.016 0.434 0.997 Cr 0.223 0.259 -0.254 -0.118 -0.391 0.493 -0.188 -0.331 -0.257 -0.377 -0.119 -0.162 -0.119 - 0.574 0.891 0.558 0.048 0.068 0.434 0.221 0.009 0.745 Cu -0.805 -0.744 0.730 -0.451 -0.121 -0.609 -0.381 0.592 -0.344 0.511 -0.206 0.728 0.704 -0.203 - 0.545 0.001 0.280 0.061 0.009 0.004 0.009 0.264 Ni -0.099 0.011 -0.045 0.200 0.015 -0.083 0.272 -0.015 0.313 -0.007 -0.147 -0.028 -0.056 -0.050 0.218 - 0.403 0.269 0.433 0.997 0.969 0.019 0.148 Zn -0.922 -0.833 0.822 -0.650 -0.370 -0.608 -0.558 0.517 -0.468 0.299 -0.164 0.874 0.833 -0.211 0.865 0.298 - 0.357 0.179 0.004 0.023 0.018 0.603 Pb -0.381 -0.323 0.313 -0.550 -0.359 0.007 -0.483 0.149 -0.580 0.050 -0.130 0.402 0.419 0.636 0.379 -0.387 0.327 - 0.662 0.382 0.495 0.176 0.017 Sr -0.557 -0.599 0.579 -0.155 0.366 -0.664 -0.066 0.646 -0.036 0.745 -0.007 0.490 0.506 -0.598 0.610 -0.280 0.462 0.158 - 0.055 0.005 0.170 0.003 Cl -0.954 -0.994 0.979 -0.378 -0.099 -0.905 -0.552 0.868 -0.318 0.630 0.239 0.951 0.947 -0.280 0.770 -0.001 0.819 0.311 0.621 - 0.001 0.866 0.008 Ba -0.829 -0.847 0.799 -0.139 0.263 -0.897 -0.187 0.907 -0.051 0.819 0.208 0.740 0.731 -0.425 0.822 0.014 0.703 0.245 0.804 0.888 - 0.001 0.781 Zr 0.945 0.950 0.284 0.651 0.493 0.842 -0.436 0.396 -0.718 -0.325 -0.967 -0.919 -0.924 -0.661 -0.805 -0.744 -0.201 0.257 -0.488 0.627 0.067 - 0.069 Rb 0.939 0.927 0.350 0.777 0.684 0.704 -0.439 0.645 -0.636 -0.207 -0.920 -0.911 -0.873 -0.754 -0.714 -0.732 -0.541 0.099 -0.647 0.848 0.098 -0.411 -0.319 129 b) Caviglia et al., 2019 Log (10) size Si Ca Fe Al Na Mg Ti K P Mn S Cr Cu Ni Zn Pb Sr Cl Log(10) size 0.00 0.00 0.94 0.89 0.09 0.64 0.00 0.16 0.00 0.03 0.00 0.40 0.50 0.00 0.00 0.00 0.05 0.00 Si 0.91 - 0.00 0.76 0.38 0.28 0.40 0.00 0.57 0.00 0.02 0.00 0.35 0.69 0.00 0.00 0.00 0.04 0.00 Ca -0.91 -0.96 - 0.66 0.44 0.39 0.75 0.00 0.52 0.00 0.05 0.00 0.44 0.39 0.00 0.02 0.00 0.06 0.00 Fe 0.03 -0.11 -0.16 - 0.84 0.23 0.02 0.95 0.78 0.62 0.21 0.75 0.52 0.43 0.59 0.35 0.89 0.99 0.94 Al -0.05 0.31 -0.28 -0.07 - 0.11 0.87 0.85 0.14 0.96 0.90 0.37 0.61 0.77 0.52 0.89 0.88 0.65 0.54 Na 0.57 0.38 -0.30 -0.42 -0.54 - 0.10 0.03 0.04 0.06 0.02 0.40 0.29 0.37 0.45 0.04 0.08 0.54 0.21 Mg -0.17 -0.30 0.12 0.72 -0.06 -0.54 - 0.41 0.96 0.42 0.04 0.76 0.39 0.64 0.86 0.05 0.65 0.24 0.64 Ti -0.90 -0.83 0.84 -0.02 0.07 -0.69 0.29 - 0.04 0.00 0.01 0.01 0.18 0.26 0.01 0.00 0.00 0.10 0.00 K -0.48 -0.21 0.23 -0.10 0.51 -0.65 0.02 0.65 - 0.15 0.30 0.78 0.28 0.50 0.72 0.18 0.15 0.55 0.42 P -0.91 -0.88 0.82 0.18 -0.02 -0.62 0.29 0.87 0.49 - 0.05 0.01 0.59 0.77 0.02 0.00 0.00 0.07 0.00 Mn -0.67 -0.72 0.62 0.44 -0.05 -0.72 0.66 0.78 0.37 0.63 - 0.05 0.03 0.32 0.07 0.01 0.08 0.26 0.02 S -0.85 -0.92 0.97 -0.11 -0.32 -0.30 0.11 0.79 0.10 0.75 0.64 - 0.38 0.22 0.00 0.05 0.00 0.17 0.00 Cr 0.30 0.33 -0.27 -0.23 0.18 0.37 -0.30 -0.46 -0.38 -0.19 -0.68 -0.31 - 0.41 0.45 0.22 0.63 0.55 0.29 Cu 0.24 0.14 -0.31 0.28 -0.10 0.32 0.17 -0.40 -0.24 -0.11 -0.35 -0.43 0.29 - 0.29 0.85 0.44 0.23 0.28 Ni -0.89 -0.90 0.97 -0.20 -0.23 -0.27 0.06 0.76 0.13 0.72 0.60 0.97 -0.27 -0.37 - 0.06 0.00 0.11 0.00 Zn -0.81 -0.83 0.72 0.33 -0.05 -0.66 0.63 0.85 0.46 0.86 0.80 0.63 -0.42 0.07 0.62 - 0.01 0.01 0.01 Pb -0.96 -0.85 0.88 -0.05 0.05 -0.58 0.17 0.88 0.49 0.93 0.58 0.81 -0.17 -0.28 0.84 0.77 - 0.07 0.00 Sr -0.63 -0.66 0.61 0.00 -0.16 -0.22 0.41 0.55 0.22 0.60 0.39 0.47 -0.22 0.42 0.53 0.80 0.59 - 0.14 Cl -0.89 -0.94 0.95 -0.03 -0.22 -0.43 0.17 0.89 0.29 0.85 0.72 0.96 -0.37 -0.38 0.90 0.75 0.83 0.50 - 130 c) Loginova et al., 2019 a) Log (10) size Si Ca Fe Al Na Mg Ti Mn S Cr Cu Ni Zn Pb Ba Sb Log (10) size 0.000 0.000 0.001 0.025 0.663 0.778 0.001 0.035 0.000 0.000 0.000 0.000 0.017 0.000 0.074 0.000 Si 0.914 - 0.000 0.000 0.017 0.580 0.214 0.000 0.009 0.000 0.003 0.000 0.000 0.001 0.000 0.008 0.000 Ca -0.919 -0.954 - 0.004 0.113 0.627 0.356 0.000 0.001 0.000 0.001 0.000 0.000 0.002 0.000 0.018 0.000 Fe -0.797 -0.817 0.719 - 0.005 0.674 0.385 0.047 0.159 0.010 0.001 0.004 0.000 0.024 0.001 0.179 0.001 Al -0.595 -0.624 0.442 0.706 - 0.404 0.667 0.164 0.896 0.056 0.058 0.023 0.021 0.080 0.037 0.042 0.032 Na 0.128 -0.162 0.142 0.124 -0.242 - 0.000 0.976 0.255 0.518 0.614 0.733 0.515 0.138 0.722 0.296 0.976 Mg -0.083 -0.354 0.267 0.252 0.126 0.855 - 0.636 0.294 0.977 0.864 0.228 0.961 0.022 0.262 0.014 0.623 Ti -0.769 -0.847 0.865 0.539 0.394 0.009 0.139 - 0.005 0.000 0.012 0.002 0.005 0.073 0.003 0.015 0.000 Mn -0.564 -0.671 0.781 0.398 0.038 0.326 0.302 0.706 - 0.010 0.013 0.010 0.058 0.015 0.004 0.075 0.019 S -0.956 -0.894 0.935 0.663 0.521 -0.189 -0.008 0.876 0.661 - 0.001 0.000 0.000 0.027 0.000 0.052 0.000 Cr -0.823 -0.737 0.803 0.770 0.518 -0.148 -0.050 0.648 0.643 0.805 - 0.001 0.000 0.053 0.000 0.161 0.000 Cu -0.915 -0.936 0.943 0.711 0.601 0.100 0.344 0.754 0.664 0.891 0.767 - 0.000 0.001 0.000 0.004 0.000 Ni -0.928 -0.810 0.839 0.810 0.608 -0.190 -0.014 0.706 0.517 0.883 0.916 0.839 - 0.098 0.000 0.121 0.000 Zn -0.625 -0.788 0.753 0.597 0.484 0.417 0.604 0.493 0.636 0.587 0.527 0.806 0.460 - 0.002 0.003 0.027 Pb -0.921 -0.919 0.930 0.775 0.560 0.104 0.322 0.726 0.715 0.872 0.827 0.963 0.881 0.743 - 0.021 0.000 Ba -0.491 -0.672 0.622 0.381 0.549 0.301 0.638 0.633 0.490 0.528 0.396 0.720 0.434 0.723 0.609 - 0.019 Sb -0.917 -0.924 0.932 0.779 0.573 -0.009 0.144 0.910 0.618 0.934 0.821 0.869 0.897 0.589 0.846 0.618 - 131 d) this work: data from < 2mm grain size Log (10) size Si Ca Fe Al Na Mg Ti K P Mn LOI Log (10) size 0.00 0.01 0.01 0.01 0.16 0.02 0.91 0.00 0.00 0.73 0.00 Si 0.91 - 0.00 0.01 0.00 0.04 0.00 0.75 0.00 0.02 0.82 0.00 Ca -0.86 -0.99 - 0.01 0.00 0.05 0.00 0.84 0.00 0.04 0.60 0.00 Fe 0.89 0.90 -0.90 - 0.01 0.28 0.00 0.65 0.00 0.01 0.66 0.00 Al 0.86 0.99 -0.98 0.89 - 0.03 0.00 0.87 0.01 0.03 0.70 0.00 Na 0.60 0.79 -0.76 0.48 0.79 - 0.06 0.16 0.21 0.26 0.85 0.05 Mg 0.85 0.98 -1.00 0.91 0.97 0.74 - 0.85 0.00 0.05 0.55 0.00 Ti -0.05 -0.15 0.09 0.21 -0.08 -0.60 -0.09 - 0.84 0.98 0.29 0.82 K 0.93 0.92 -0.92 0.97 0.89 0.54 0.93 0.10 - 0.02 0.72 0.00 P 0.93 0.84 -0.77 0.87 0.80 0.50 0.76 0.01 0.84 - 0.58 0.01 Mn -0.16 0.10 -0.24 0.21 0.18 -0.09 0.27 0.47 0.17 -0.26 - 0.87 LOI -0.92 -1.00 0.98 -0.92 -0.98 -0.76 -0.97 0.11 -0.93 -0.87 -0.08 - 132 APPENDIX II XRD analysis: phase identification and semi-quantitive estimation in XRD pattern of bulk sample (1) and colourbased selected clast: (2) gray. (3) green/transparent. (4) metallic part. (5) white. and (6) red/dark. The semi-quantitive content are represented as: xxxx= 70-100 wt%. xxx = 40-70 wt%. xx=10-40wt%. x=<10 wt%. *=uncertainty presence. Estimated error ±10. 139 APPENDIX VII Statistical analysis between grain size and major and minor elements content; R2 (lower triangle) and p value (upper triangle) for 5 WtE plants investigated a) Parma WtE plant PARMA Grain size SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI As Ba Ce Cl Co Cr Cu Ga Hf La Mo Nb Nd Ni Pb Rb S Sc Sn Sr Th V Y Zn Zr Grain size - 9E-08 0.0078 0.528 0.096 0.498 0.050 9E-06 0.002 0.218 0.093 2E-06 0.009 0.002 0.889 2E-05 0.044 0.741 0.006 0.239 0.023 0.464 0.465 0.331 0.217 0.784 0.135 9E-05 7E-06 0.029 0.000 0.052 0.776 0.102 0.024 0.002 1E-04 SiO2 0.988 - 0.0075 0.476 0.095 0.488 0.028 7E-08 0.002 0.200 0.095 7E-09 0.010 0.004 0.655 7E-06 0.055 0.683 0.014 0.306 0.014 0.322 0.423 0.329 0.167 0.980 0.169 5E-05 1E-07 0.022 0.000 0.049 0.804 0.117 0.018 0.005 4E-05 TiO2 -0.780 -0.782 - 0.306 0.901 0.128 0.630 0.005 0.000 0.749 0.000 0.010 0.050 0.000 0.896 0.000 0.011 0.448 0.073 0.709 0.078 0.494 0.243 0.710 0.557 0.972 0.377 0.048 0.007 0.053 0.002 0.022 0.519 0.002 0.526 0.092 0.019 Al2O3 0.227 0.255 0.361 - 0.005 0.404 0.005 0.556 0.528 0.004 0.066 0.399 0.489 0.418 0.204 0.976 0.754 0.217 0.770 0.296 0.440 0.935 0.910 0.003 0.327 0.926 0.458 0.322 0.461 0.808 0.884 0.340 0.065 0.077 0.014 0.543 0.427 Fe2O3 0.555 0.557 0.045 0.809 - 0.360 0.003 0.157 0.850 0.000 0.460 0.101 0.167 0.684 0.542 0.347 0.791 0.728 0.181 0.159 0.147 0.420 0.877 0.063 0.134 0.610 0.131 0.029 0.132 0.564 0.236 0.596 0.095 0.434 0.000 0.135 0.148 MnO -0.243 -0.249 0.515 0.297 0.325 - 0.924 0.380 0.178 0.853 0.287 0.424 0.221 0.340 0.551 0.252 0.164 0.998 0.797 0.445 0.953 0.982 0.057 0.612 0.954 0.918 0.764 0.566 0.500 0.585 0.559 0.800 0.571 0.301 0.834 0.675 0.360 MgO 0.632 0.689 -0.174 0.805 0.836 -0.035 - 0.031 0.446 0.001 0.772 0.020 0.044 0.568 0.167 0.128 0.671 0.535 0.292 0.298 0.049 0.345 0.583 0.039 0.165 0.463 0.192 0.008 0.025 0.436 0.255 0.691 0.136 0.590 0.000 0.242 0.042 CaO -0.962 -0.989 0.806 -0.212 -0.483 0.312 -0.679 - 0.001 0.251 0.071 0.000 0.016 0.004 0.567 0.000 0.058 0.569 0.022 0.420 0.022 0.261 0.443 0.356 0.173 0.990 0.273 0.000 0.000 0.012 0.001 0.044 0.998 0.097 0.029 0.010 0.000 Na2O 0.846 0.856 -0.963 -0.227 0.069 -0.463 0.273 -0.886 - 0.918 0.002 0.002 0.084 0.000 0.979 0.000 0.016 0.270 0.048 0.761 0.114 0.371 0.385 0.963 0.332 0.740 0.586 0.023 0.002 0.007 0.002 0.020 0.366 0.002 0.407 0.029 0.002 K2O 0.427 0.443 0.116 0.819 0.907 0.067 0.879 -0.401 -0.038 - 0.320 0.192 0.118 0.940 0.533 0.496 0.607 0.484 0.386 0.245 0.263 0.454 0.936 0.059 0.201 0.400 0.180 0.044 0.251 0.887 0.455 0.870 0.067 0.214 0.000 0.510 0.257 P2O5 -0.559 -0.557 0.909 0.601 0.265 0.374 0.105 0.593 -0.841 0.351 - 0.133 0.198 0.001 0.994 0.019 0.063 0.315 0.113 0.626 0.167 0.361 0.445 0.345 0.757 0.964 0.463 0.205 0.084 0.094 0.024 0.007 0.325 0.004 0.969 0.238 0.208 LOI -0.975 -0.994 0.763 -0.300 -0.548 0.286 -0.716 0.989 -0.849 -0.450 0.509 - 0.013 0.008 0.619 0.000 0.047 0.722 0.024 0.376 0.021 0.369 0.400 0.257 0.161 0.918 0.232 0.000 0.000 0.024 0.002 0.091 0.832 0.129 0.018 0.007 0.000 As -0.768 -0.765 0.633 -0.249 -0.473 0.425 -0.646 0.731 -0.572 -0.527 0.445 0.747 - 0.064 0.578 0.020 0.086 0.328 0.149 0.090 0.004 0.474 0.041 0.552 0.338 0.447 0.006 0.007 0.008 0.580 0.023 0.214 0.110 0.614 0.020 0.302 0.069 Ba -0.842 -0.820 0.931 0.289 -0.147 0.338 -0.206 0.822 -0.932 -0.028 0.869 0.780 0.604 - 0.728 0.000 0.076 0.245 0.007 0.421 0.104 0.324 0.611 0.930 0.299 0.912 0.296 0.016 0.007 0.026 0.000 0.002 0.497 0.003 0.332 0.024 0.014 Ce 0.051 0.162 0.047 0.440 0.220 0.215 0.474 -0.206 0.009 0.224 -0.003 -0.180 -0.201 0.126 - 0.885 0.943 0.531 0.866 0.320 0.143 0.132 0.604 0.299 0.288 0.293 0.576 0.665 0.463 0.949 0.671 0.960 0.414 0.322 0.307 0.869 0.864 Cl -0.954 -0.964 0.909 -0.011 -0.333 0.400 -0.514 0.974 -0.956 -0.244 0.721 0.955 0.717 0.914 -0.053 - 0.030 0.459 0.018 0.511 0.038 0.347 0.392 0.622 0.254 0.917 0.300 0.001 0.000 0.011 0.000 0.023 0.779 0.022 0.100 0.012 0.000 Co -0.645 -0.621 0.756 0.114 0.096 0.477 -0.154 0.615 -0.734 0.186 0.606 0.638 0.569 0.584 -0.026 0.683 - 0.547 0.292 0.568 0.142 0.544 0.088 0.810 0.869 0.251 0.390 0.238 0.032 0.298 0.100 0.604 0.949 0.069 0.729 0.129 0.067 Cr 0.120 0.148 -0.271 -0.429 -0.126 0.001 -0.224 -0.205 0.386 -0.251 -0.354 -0.129 0.346 -0.405 -0.226 -0.265 0.217 - 0.608 0.194 0.444 0.143 0.247 0.403 0.345 0.987 0.114 0.785 0.853 0.028 0.466 0.073 0.003 0.094 0.547 0.480 0.473 Cu -0.796 -0.743 0.589 -0.106 -0.460 -0.094 -0.370 0.710 -0.637 -0.309 0.532 0.700 0.492 0.786 0.062 0.724 0.371 -0.186 - 0.059 0.132 0.702 0.501 0.236 0.406 0.526 0.141 0.012 0.024 0.124 0.002 0.048 0.983 0.148 0.081 0.001 0.037 Ga -0.410 -0.361 0.135 -0.368 -0.482 -0.273 -0.366 0.288 -0.110 -0.405 0.176 0.315 0.564 0.287 -0.351 0.236 0.206 0.448 0.614 - 0.066 0.730 0.861 0.141 0.383 0.965 0.004 0.215 0.287 0.752 0.270 0.508 0.075 0.647 0.080 0.283 0.670 Hf 0.704 0.741 -0.581 0.276 0.494 0.021 0.635 -0.707 0.531 0.392 -0.473 -0.711 -0.821 -0.544 0.498 -0.658 -0.499 -0.274 -0.510 -0.601 - 0.315 0.183 0.586 0.376 0.259 0.004 0.022 0.006 0.544 0.043 0.159 0.112 0.614 0.023 0.183 0.124 La 0.262 0.350 -0.246 0.030 0.288 -0.008 0.334 -0.393 0.318 0.268 -0.324 -0.319 -0.257 -0.348 0.510 -0.333 0.218 0.498 -0.139 -0.125 0.354 - 0.733 0.858 0.012 0.064 0.801 0.245 0.359 0.181 0.448 0.032 0.742 0.869 0.350 0.894 0.478 Mo -0.262 -0.286 0.407 0.041 0.056 0.617 -0.198 0.274 -0.309 -0.029 0.273 0.300 0.651 0.184 -0.187 0.305 0.566 0.404 -0.242 0.064 -0.459 -0.124 - 0.528 0.719 0.439 0.289 0.604 0.345 0.881 0.634 0.917 0.271 0.829 0.764 0.626 0.596 Nb 0.344 0.345 0.135 0.826 0.607 0.183 0.658 -0.328 0.017 0.614 0.335 -0.396 -0.214 0.032 0.365 -0.178 -0.088 -0.298 -0.413 -0.500 0.197 -0.065 0.227 - 0.272 0.413 0.630 0.285 0.322 0.899 0.782 0.496 0.406 0.445 0.038 0.214 0.215 Nd 0.428 0.474 -0.212 0.346 0.508 -0.021 0.476 -0.468 0.343 0.442 -0.113 -0.479 -0.339 -0.366 0.374 -0.398 0.060 0.334 -0.296 -0.310 0.315 0.755 -0.131 0.385 - 0.396 0.701 0.199 0.229 0.299 0.299 0.220 0.987 0.828 0.117 0.426 0.155 Ni -0.100 -0.009 0.013 0.034 0.184 0.037 0.263 -0.005 -0.121 0.300 -0.016 0.038 -0.272 0.040 0.370 0.038 0.401 -0.006 0.228 -0.016 0.395 0.604 -0.277 -0.292 0.302 - 0.360 0.787 0.985 0.521 0.975 0.483 0.329 0.491 0.438 0.221 0.627 Pb -0.507 -0.471 0.314 -0.266 -0.512 -0.109 -0.450 0.385 -0.197 -0.461 0.263 0.415 0.795 0.368 -0.202 0.365 0.306 0.532 0.500 0.811 -0.820 -0.092 0.373 -0.174 -0.139 -0.325 - 0.106 0.147 0.662 0.112 0.376 0.008 0.850 0.046 0.405 0.577 Rb 0.932 0.939 -0.636 0.350 0.684 -0.207 0.777 -0.927 0.704 0.645 -0.439 -0.920 -0.790 -0.732 0.157 -0.873 -0.411 0.099 -0.754 -0.430 0.707 0.406 -0.188 0.376 0.444 0.098 -0.541 - 0.000 0.045 0.002 0.043 0.565 0.368 0.003 0.020 0.002 S -0.964 -0.988 0.789 -0.264 -0.511 0.242 -0.698 0.984 -0.851 -0.401 0.572 0.986 0.776 0.784 -0.263 0.951 0.677 -0.067 0.702 0.374 -0.798 -0.325 0.334 -0.350 -0.419 -0.007 0.493 -0.911 - 0.034 0.002 0.075 0.720 0.137 0.021 0.009 0.000 Sc -0.685 -0.709 0.625 0.088 -0.208 0.197 -0.279 0.753 -0.784 -0.052 0.558 0.702 0.200 0.696 -0.023 0.756 0.366 -0.687 0.519 -0.115 -0.218 -0.460 -0.055 -0.046 -0.366 0.231 -0.159 -0.642 0.669 - 0.049 0.024 0.120 0.049 0.534 0.026 0.010 Sn -0.929 -0.896 0.843 0.053 -0.413 0.211 -0.398 0.863 -0.850 -0.267 0.702 0.855 0.703 0.946 0.154 0.919 0.549 -0.261 0.847 0.386 -0.647 -0.271 0.172 -0.101 -0.365 0.011 0.533 -0.847 0.851 0.633 - 0.008 0.992 0.027 0.097 0.006 0.005 Sr -0.628 -0.634 0.707 0.338 -0.192 0.092 -0.144 0.645 -0.715 -0.060 0.790 0.562 0.431 0.847 -0.018 0.703 0.188 -0.590 0.637 0.238 -0.481 -0.675 0.038 0.244 -0.426 -0.252 0.315 -0.647 0.586 0.700 0.781 - 0.470 0.067 0.436 0.137 0.153 Th -0.104 -0.090 -0.232 -0.604 -0.556 -0.204 -0.506 -0.001 0.321 -0.599 -0.348 0.077 0.536 -0.244 -0.291 -0.102 0.023 0.829 -0.008 0.586 -0.534 0.120 0.386 -0.296 0.006 -0.345 0.776 -0.208 0.130 -0.524 -0.004 -0.259 - 0.068 0.089 0.813 0.784 V -0.546 -0.527 0.856 0.583 0.279 0.364 0.195 0.554 -0.849 0.431 0.813 0.513 0.182 0.824 0.349 0.707 0.595 -0.558 0.492 -0.166 -0.183 -0.060 0.079 0.273 -0.079 0.247 -0.069 -0.319 0.504 0.635 0.690 0.600 -0.599 - 0.725 0.098 0.085 Y 0.700 0.724 -0.228 0.743 0.900 0.076 0.941 -0.683 0.295 0.897 0.014 -0.724 -0.714 -0.343 0.360 -0.549 -0.126 -0.217 -0.577 -0.579 0.705 0.331 -0.109 0.660 0.527 0.278 -0.640 0.828 -0.711 -0.224 -0.554 -0.279 -0.564 0.128 - 0.130 0.050 Zn -0.845 -0.805 0.561 -0.219 -0.507 -0.152 -0.408 0.762 -0.684 -0.237 0.411 0.789 0.364 0.702 0.060 0.753 0.514 -0.254 0.860 0.377 -0.458 -0.049 -0.177 -0.430 -0.284 0.425 0.297 -0.714 0.772 0.694 0.796 0.504 -0.086 0.552 -0.512 - 0.005 Zr 0.930 0.945 -0.718 0.284 0.493 -0.325 0.651 -0.950 0.842 0.396 -0.436 -0.967 -0.596 -0.744 0.062 -0.924 -0.600 0.257 -0.661 -0.154 0.520 0.254 -0.191 0.430 0.486 -0.176 -0.201 0.848 -0.919 -0.764 -0.801 -0.488 0.100 -0.570 0.633 -0.805 - 140 b) Piacenza WtE plant PIACENZA Grain size SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI As Ba Ce Cl Co Cr Cu Ga La Mo Nb Nd Ni Pb Rb S Sc Sn Sr Th V Y Zn Zr Grain size - 0.003 0.050 0.001 0.091 0.269 0.796 0.014 0.014 0.657 0.113 0.161 0.318 0.656 0.289 0.008 0.973 0.159 0.002 0.065 0.844 0.107 0.871 0.620 0.849 0.289 0.766 0.133 0.116 0.073 0.073 0.128 0.236 0.952 0.098 0.235 SiO2 0.919 - 0.049 0.000 0.009 0.744 0.675 0.000 0.012 0.657 0.066 0.105 0.295 0.447 0.154 0.001 0.910 0.212 0.004 0.014 0.373 0.036 0.974 0.824 0.572 0.183 0.690 0.028 0.107 0.168 0.045 0.078 0.248 0.486 0.141 0.169 TiO2 -0.755 -0.756 - 0.027 0.116 0.536 0.304 0.026 0.001 0.055 0.005 0.410 0.009 0.067 0.016 0.004 0.548 0.999 0.026 0.031 0.723 0.011 0.149 0.817 0.722 0.009 0.072 0.012 0.007 0.012 0.000 0.001 0.008 0.456 0.002 0.999 Al2O3 -0.944 -0.972 0.812 - 0.016 0.671 0.783 0.000 0.010 0.529 0.048 0.249 0.231 0.389 0.105 0.001 0.846 0.255 0.004 0.007 0.671 0.040 0.900 0.609 0.574 0.168 0.599 0.030 0.078 0.137 0.043 0.062 0.240 0.499 0.114 0.272 Fe2O3 0.682 0.880 -0.647 -0.848 - 0.620 0.657 0.002 0.080 0.703 0.128 0.292 0.261 0.193 0.078 0.015 0.522 0.507 0.084 0.001 0.242 0.018 0.955 0.645 0.256 0.117 0.642 0.014 0.313 0.359 0.082 0.094 0.417 0.084 0.348 0.420 MnO -0.486 -0.152 0.285 0.198 0.230 - 0.685 0.988 0.504 0.907 0.957 0.587 0.798 0.585 0.631 0.740 0.336 0.682 0.424 0.770 0.495 0.930 0.536 0.918 0.297 0.991 0.931 0.700 0.507 0.135 0.633 0.859 0.448 0.061 0.315 0.828 MgO 0.121 0.195 0.456 -0.129 0.207 0.189 - 0.823 0.492 0.011 0.328 0.845 0.058 0.119 0.295 0.828 0.301 0.122 0.897 0.981 0.770 0.471 0.002 0.347 0.044 0.144 0.009 0.586 0.414 0.213 0.298 0.218 0.063 0.797 0.134 0.041 CaO -0.855 -0.972 0.812 0.972 -0.930 0.007 -0.105 - 0.012 0.472 0.033 0.236 0.185 0.244 0.054 0.000 0.839 0.377 0.012 0.001 0.421 0.015 0.849 0.760 0.493 0.100 0.492 0.006 0.083 0.186 0.028 0.038 0.220 0.266 0.129 0.319 Na2O 0.855 0.863 -0.948 -0.875 0.699 -0.306 -0.315 -0.865 - 0.125 0.003 0.139 0.032 0.151 0.038 0.001 0.717 0.561 0.001 0.033 0.587 0.006 0.289 0.857 0.677 0.025 0.149 0.011 0.026 0.017 0.001 0.003 0.015 0.520 0.003 0.676 K2O -0.206 -0.207 0.745 0.289 -0.177 0.055 0.872 0.328 -0.636 - 0.031 0.911 0.007 0.029 0.031 0.259 0.460 0.393 0.367 0.360 0.901 0.127 0.023 0.520 0.186 0.027 0.000 0.126 0.107 0.136 0.070 0.025 0.015 0.426 0.028 0.233 P2O5 -0.651 -0.724 0.903 0.758 -0.632 0.025 0.436 0.793 -0.921 0.800 - 0.320 0.020 0.069 0.005 0.008 0.778 0.771 0.024 0.043 0.687 0.010 0.274 0.788 0.617 0.018 0.040 0.004 0.029 0.102 0.008 0.001 0.021 0.291 0.012 0.935 LOI -0.592 -0.662 0.373 0.504 -0.466 0.251 -0.091 0.516 -0.618 0.052 0.442 - 0.609 0.885 0.707 0.178 0.818 0.189 0.066 0.486 0.136 0.220 0.897 0.502 0.635 0.457 0.864 0.306 0.531 0.301 0.236 0.346 0.292 0.967 0.294 0.209 As -0.444 -0.463 0.882 0.520 -0.493 0.120 0.738 0.566 -0.798 0.894 0.832 0.237 - 0.003 0.008 0.076 0.693 0.525 0.164 0.098 0.785 0.012 0.016 0.758 0.431 0.000 0.005 0.034 0.108 0.024 0.006 0.001 0.005 0.243 0.009 0.350 Ba -0.207 -0.346 0.722 0.388 -0.558 -0.252 0.643 0.508 -0.604 0.804 0.719 0.068 0.918 - 0.005 0.172 0.982 0.321 0.423 0.084 0.600 0.021 0.056 0.837 0.797 0.002 0.013 0.033 0.279 0.186 0.045 0.015 0.069 0.038 0.119 0.248 Ce -0.469 -0.600 0.846 0.663 -0.703 -0.223 0.464 0.747 -0.780 0.800 0.908 0.175 0.884 0.908 - 0.032 0.921 0.799 0.144 0.015 0.709 0.006 0.216 0.963 0.960 0.005 0.026 0.002 0.104 0.184 0.019 0.002 0.068 0.057 0.066 0.660 Cl -0.887 -0.950 0.910 0.960 -0.851 0.155 0.102 0.969 -0.962 0.495 0.884 0.574 0.707 0.580 0.795 - 0.971 0.448 0.002 0.005 0.502 0.005 0.538 0.908 0.868 0.043 0.284 0.004 0.042 0.064 0.005 0.008 0.076 0.352 0.033 0.478 Co 0.016 0.053 0.276 -0.091 0.294 0.430 0.458 -0.095 -0.169 0.337 0.132 0.108 0.184 0.011 -0.046 0.017 - 0.356 0.977 0.587 0.625 0.913 0.315 0.017 0.257 0.745 0.498 0.966 0.180 0.463 0.542 0.710 0.266 0.339 0.321 0.950 Cr -0.595 -0.539 0.001 0.499 -0.304 0.191 -0.639 0.398 -0.268 -0.386 0.136 0.562 -0.292 -0.442 -0.119 0.345 -0.414 - 0.192 0.664 0.968 0.869 0.144 0.368 0.664 0.586 0.315 0.869 0.964 0.960 0.964 0.910 0.697 0.656 0.944 0.033 Cu -0.941 -0.917 0.814 0.914 -0.694 0.363 0.061 0.866 -0.947 0.405 0.818 0.724 0.589 0.364 0.612 0.936 0.013 0.559 - 0.057 0.659 0.034 0.647 0.887 0.819 0.140 0.428 0.049 0.091 0.057 0.027 0.041 0.096 0.727 0.038 0.344 Ga -0.725 -0.854 0.799 0.890 -0.947 -0.137 0.011 0.944 -0.794 0.411 0.769 0.319 0.673 0.694 0.853 0.909 -0.251 0.202 0.740 - 0.545 0.006 0.655 0.544 0.421 0.046 0.349 0.004 0.168 0.205 0.034 0.027 0.245 0.087 0.172 0.704 La -0.092 -0.401 0.165 0.197 -0.510 -0.312 -0.137 0.365 -0.251 -0.058 0.187 0.622 0.128 0.243 0.174 0.307 0.227 -0.019 0.205 0.278 - 0.353 0.934 0.182 0.697 0.460 0.905 0.314 0.708 0.848 0.420 0.555 0.594 0.378 0.770 0.439 Mo -0.660 -0.786 0.871 0.777 -0.839 -0.041 0.329 0.851 -0.897 0.633 0.876 0.531 0.864 0.829 0.898 0.906 -0.051 0.077 0.791 0.895 0.416 - 0.238 0.957 0.956 0.002 0.101 0.001 0.136 0.064 0.002 0.001 0.039 0.105 0.038 0.997 Nb -0.076 -0.016 0.606 0.059 -0.027 0.285 0.936 0.089 -0.468 0.824 0.481 0.061 0.846 0.742 0.535 0.284 0.447 -0.613 0.213 0.207 0.039 0.514 - 0.389 0.123 0.046 0.016 0.387 0.317 0.059 0.118 0.106 0.022 0.668 0.061 0.085 Nd -0.230 -0.104 -0.108 0.237 -0.214 -0.048 -0.421 0.143 0.084 -0.295 -0.126 -0.308 -0.144 -0.097 0.022 0.054 -0.845 0.404 0.067 0.279 -0.569 -0.025 -0.388 - 0.252 0.687 0.454 0.842 0.445 0.782 0.632 0.742 0.332 0.755 0.521 0.945 Ni 0.089 0.261 0.166 -0.260 0.498 0.462 0.767 -0.314 -0.194 0.565 0.232 0.220 0.358 0.120 0.024 -0.078 0.497 -0.202 0.107 -0.365 -0.181 0.026 0.638 -0.501 - 0.652 0.211 0.864 0.711 0.371 0.682 0.637 0.197 0.419 0.280 0.336 Pb -0.468 -0.568 0.881 0.584 -0.645 -0.006 0.612 0.669 -0.818 0.810 0.840 0.339 0.971 0.941 0.909 0.770 0.152 -0.252 0.617 0.763 0.337 0.935 0.763 -0.188 0.209 - 0.016 0.008 0.109 0.041 0.002 0.000 0.009 0.130 0.018 0.525 Rb -0.139 -0.186 0.713 0.244 -0.216 -0.041 0.879 0.315 -0.607 0.987 0.777 0.080 0.907 0.862 0.813 0.472 0.311 -0.447 0.360 0.419 0.056 0.667 0.849 -0.341 0.540 0.849 - 0.108 0.155 0.160 0.068 0.024 0.016 0.301 0.042 0.193 S -0.625 -0.808 0.866 0.802 -0.857 -0.179 0.252 0.897 -0.870 0.634 0.916 0.455 0.792 0.794 0.930 0.915 0.020 0.077 0.757 0.911 0.448 0.954 0.390 -0.093 -0.080 0.883 0.658 - 0.065 0.163 0.006 0.002 0.066 0.084 0.059 0.813 Sc -0.647 -0.659 0.889 0.703 -0.449 0.304 0.370 0.696 -0.813 0.659 0.805 0.288 0.658 0.477 0.664 0.772 0.572 -0.021 0.682 0.585 0.175 0.621 0.445 -0.347 0.173 0.657 0.599 0.725 - 0.090 0.023 0.037 0.036 0.836 0.014 0.709 Sn -0.712 -0.585 0.867 0.620 -0.411 0.623 0.538 0.565 -0.845 0.621 0.667 0.459 0.820 0.565 0.567 0.727 0.335 -0.024 0.741 0.546 0.090 0.726 0.736 -0.130 0.402 0.774 0.594 0.590 0.684 - 0.010 0.030 0.008 0.918 0.003 0.801 Sr -0.711 -0.766 0.970 0.770 -0.696 0.222 0.461 0.807 -0.950 0.716 0.887 0.515 0.898 0.766 0.835 0.905 0.281 -0.021 0.810 0.792 0.366 0.931 0.644 -0.222 0.191 0.933 0.720 0.899 0.824 0.873 - 0.000 0.004 0.354 0.002 0.994 Th -0.632 -0.703 0.956 0.731 -0.678 0.083 0.533 0.781 -0.928 0.817 0.947 0.422 0.945 0.850 0.929 0.883 0.173 -0.053 0.773 0.810 0.272 0.949 0.661 -0.154 0.219 0.963 0.821 0.931 0.785 0.803 0.972 - 0.005 0.221 0.004 0.812 V -0.516 -0.505 0.885 0.512 -0.368 0.346 0.729 0.531 -0.852 0.853 0.829 0.466 0.909 0.718 0.721 0.706 0.489 -0.181 0.676 0.508 0.247 0.779 0.827 -0.433 0.554 0.880 0.848 0.723 0.785 0.883 0.918 0.905 - 0.642 0.000 0.653 Y 0.028 0.319 -0.340 -0.310 0.693 0.733 -0.120 -0.489 0.296 -0.361 -0.467 -0.019 -0.509 -0.780 -0.740 -0.417 0.427 0.207 -0.163 -0.689 -0.397 -0.663 -0.199 -0.146 0.367 -0.629 -0.458 -0.693 -0.097 -0.048 -0.415 -0.530 -0.216 - 0.762 0.619 Zn 0.672 0.616 -0.942 -0.650 0.420 -0.447 -0.624 -0.630 0.919 -0.808 -0.864 -0.464 -0.879 -0.644 -0.723 -0.794 -0.442 0.033 -0.782 -0.580 -0.137 -0.780 -0.732 0.295 -0.476 -0.838 -0.773 -0.736 -0.854 -0.921 -0.933 -0.911 -0.973 0.141 - 0.857 Zr 0.516 0.584 0.000 -0.483 0.366 -0.102 0.775 -0.443 0.194 0.519 -0.038 -0.542 0.418 0.505 0.205 -0.324 0.029 -0.793 -0.424 -0.177 -0.352 -0.001 0.692 -0.032 0.430 0.292 0.558 -0.111 -0.174 0.118 -0.004 0.111 0.209 -0.231 -0.085 - 141 c) Torino WtE plant TORINO Grain size SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI As Ba Ce Cl Co Cr Cu Ga La Mo Nb Nd Ni Pb Rb S Sc Sn Sr Th V Y Zn Zr Grain size - 0.023 0.008 0.002 0.025 0.469 0.415 0.003 0.048 0.128 0.611 3E-07 0.235 0.006 0.036 0.009 0.612 0.000 0.000 0.014 0.068 0.771 0.563 0.928 0.727 0.143 0.899 0.019 0.261 0.001 0.000 0.263 0.098 0.165 3E-05 0.232 SiO2 0.704 - 0.680 0.261 0.999 0.005 0.326 0.551 0.016 0.829 0.371 0.053 0.756 0.542 0.703 0.000 0.338 0.011 0.154 0.518 0.298 0.250 0.512 0.262 0.075 0.824 0.075 0.681 0.908 0.293 0.110 0.977 0.040 0.244 0.0781 0.403 TiO2 -0.775 -0.149 - 0.001 0.000 0.545 0.043 0.000 0.403 0.027 0.350 0.002 0.049 0.001 0.027 0.377 0.192 0.069 0.002 0.000 0.123 0.978 0.632 0.291 0.547 0.008 0.370 0.000 0.053 0.000 0.003 0.028 0.256 0.433 0.0126 0.270 Al2O3 -0.849 -0.393 0.866 - 0.016 0.742 0.365 0.002 0.277 0.054 0.289 0.002 0.182 0.017 0.018 0.106 0.493 0.052 0.001 0.007 0.029 0.948 0.663 0.955 0.698 0.101 0.607 0.013 0.023 0.003 0.009 0.068 0.161 0.327 0.0030 0.083 Fe2O3 0.697 0.000 -0.910 -0.735 - 0.163 0.004 7E-06 0.495 0.002 0.068 0.010 0.268 0.000 0.009 0.583 0.052 0.096 0.003 0.009 0.178 0.338 0.745 0.202 0.324 0.090 0.081 0.004 0.133 0.003 0.003 0.145 0.738 0.498 0.0090 0.573 MnO -0.260 -0.800 -0.218 0.120 0.478 - 0.017 0.468 0.137 0.219 0.088 0.681 0.866 0.409 0.510 0.026 0.013 0.450 0.900 0.808 0.825 0.113 0.521 0.032 0.037 0.662 0.018 0.543 0.696 0.840 0.979 0.639 0.073 0.750 0.8009 0.426 MgO -0.291 0.347 0.647 0.321 -0.813 -0.726 - 0.043 0.718 0.011 0.222 0.245 0.539 0.005 0.192 0.795 0.027 0.642 0.135 0.115 0.733 0.372 0.350 0.034 0.541 0.269 0.029 0.108 0.263 0.187 0.106 0.289 0.980 0.888 0.1929 0.328 CaO -0.835 -0.215 0.937 0.845 -0.965 -0.260 0.648 - 0.327 0.006 0.102 0.001 0.207 0.000 0.003 0.286 0.124 0.022 0.000 0.004 0.107 0.484 0.819 0.390 0.429 0.069 0.223 0.002 0.162 0.000 0.000 0.135 0.503 0.283 0.0015 0.258 Na2O 0.635 0.733 -0.298 -0.382 0.245 -0.504 -0.131 -0.346 - 0.277 0.629 0.052 0.767 0.134 0.770 0.000 0.567 0.075 0.035 0.394 0.465 0.813 0.011 0.347 0.011 0.999 0.833 0.724 0.895 0.459 0.042 0.935 0.009 0.974 0.0497 0.879 K2O -0.515 0.079 0.690 0.624 -0.856 -0.426 0.761 0.798 -0.381 - 0.016 0.090 0.845 0.003 0.032 0.489 0.146 0.379 0.010 0.176 0.325 0.058 0.290 0.763 0.596 0.698 0.004 0.191 0.205 0.147 0.035 0.554 0.795 0.915 0.0300 0.874 P2O5 -0.184 0.318 0.331 0.373 -0.598 -0.566 0.424 0.547 0.175 0.730 - 0.615 0.498 0.228 0.020 0.658 0.086 0.805 0.302 0.884 0.491 0.002 0.456 0.897 0.032 0.749 0.004 0.609 0.567 0.446 0.449 0.978 0.147 0.748 0.3019 0.453 LOI -0.984 -0.625 0.839 0.846 -0.766 0.149 0.405 0.875 -0.627 0.563 0.182 - 0.152 0.001 0.047 0.019 0.439 0.000 3E-05 0.004 0.046 0.772 0.493 0.712 0.770 0.072 0.971 0.007 0.193 0.000 0.000 0.148 0.078 0.189 4E-05 0.298 As -0.413 -0.113 0.635 0.459 -0.388 -0.062 0.221 0.437 0.108 -0.071 -0.243 0.489 - 0.314 0.515 0.986 0.428 0.210 0.359 0.005 0.233 0.070 0.560 0.082 0.523 0.000 0.363 0.004 0.227 0.023 0.252 0.002 0.295 0.133 0.452 0.310 Ba -0.794 -0.219 0.876 0.726 -0.941 -0.294 0.801 0.929 -0.508 0.830 0.419 0.859 0.355 - 0.022 0.207 0.086 0.032 0.000 0.009 0.186 0.600 0.316 0.250 0.888 0.121 0.200 0.011 0.184 0.005 0.000 0.180 0.309 0.455 0.001 0.848 Ce 0.664 0.138 -0.690 -0.723 0.771 0.237 -0.450 -0.832 0.107 -0.675 -0.714 -0.638 -0.234 -0.709 - 0.516 0.114 0.074 0.030 0.127 0.368 0.305 0.613 0.456 0.157 0.348 0.215 0.060 0.494 0.011 0.031 0.419 0.844 0.099 0.019 0.188 Cl -0.774 -0.919 0.314 0.542 -0.198 0.695 -0.095 0.375 -0.912 0.248 -0.160 0.718 0.006 0.437 -0.233 - 0.467 0.018 0.028 0.354 0.237 0.532 0.115 0.219 0.042 0.891 0.424 0.597 0.720 0.257 0.035 0.931 0.010 0.518 0.019 0.571 Co 0.184 -0.339 -0.450 -0.246 0.629 0.745 -0.691 -0.520 -0.207 -0.495 -0.570 -0.277 -0.283 -0.569 0.531 0.261 - 0.591 0.352 0.338 0.531 0.371 0.645 0.036 0.131 0.310 0.115 0.211 0.392 0.247 0.289 0.291 0.525 0.497 0.374 0.966 Cr -0.912 -0.759 0.596 0.628 -0.554 0.270 0.168 0.708 -0.586 0.313 0.090 0.900 0.434 0.675 -0.588 0.722 -0.194 - 0.007 0.057 0.091 0.679 0.953 0.746 0.747 0.156 0.545 0.054 0.798 0.004 0.001 0.335 0.170 0.023 0.002 0.270 Cu -0.917 -0.486 0.855 0.877 -0.828 0.046 0.507 0.909 -0.666 0.767 0.363 0.946 0.325 0.907 -0.683 0.686 -0.330 0.783 - 0.009 0.043 0.750 0.293 0.909 0.837 0.162 0.440 0.022 0.140 0.004 0.000 0.172 0.093 0.359 0.000 0.330 Ga -0.743 -0.233 0.952 0.786 -0.773 -0.088 0.530 0.821 -0.303 0.465 0.053 0.818 0.805 0.774 -0.516 0.328 -0.339 0.618 0.769 - 0.134 0.476 0.642 0.231 0.794 0.000 0.862 0.000 0.082 0.000 0.008 0.008 0.111 0.345 0.040 0.279 La 0.598 0.366 -0.520 -0.683 0.463 -0.081 -0.124 -0.541 0.262 -0.347 -0.247 -0.640 -0.415 -0.455 0.319 -0.411 0.225 -0.562 -0.648 -0.508 - 0.801 0.947 0.816 0.677 0.204 0.982 0.168 0.042 0.083 0.096 0.033 0.225 0.193 0.040 0.246 Mo -0.106 -0.402 -0.010 0.024 0.339 0.532 -0.317 -0.251 -0.086 -0.617 -0.844 0.105 0.595 -0.189 0.361 0.225 0.318 0.150 -0.116 0.256 -0.092 - 0.774 0.700 0.231 0.208 0.003 0.678 0.668 0.768 0.915 0.243 0.082 0.522 0.856 0.931 Nb -0.209 -0.236 0.174 0.158 -0.118 0.231 0.331 0.083 -0.761 0.372 -0.267 0.246 -0.210 0.354 0.183 0.530 0.167 0.022 0.370 0.168 0.024 0.104 - 0.592 0.010 0.777 0.666 0.876 0.506 0.830 0.419 0.947 0.031 0.167 0.448 0.194 Nd 0.033 -0.392 -0.371 0.020 0.441 0.675 -0.670 -0.306 -0.333 -0.110 -0.047 -0.134 -0.575 -0.401 0.267 0.426 0.666 -0.118 -0.042 -0.417 -0.085 -0.140 0.194 - 0.253 0.075 0.681 0.132 0.808 0.264 0.541 0.187 0.582 0.388 0.839 0.396 Ni -0.127 -0.586 -0.217 -0.141 0.348 0.662 -0.220 -0.283 -0.759 -0.192 -0.674 0.106 -0.230 -0.051 0.483 0.649 0.512 0.117 0.075 -0.095 0.151 0.417 0.766 0.399 - 0.514 0.215 0.399 0.644 0.472 0.807 0.435 0.025 0.385 0.872 0.320 Pb -0.498 -0.081 0.775 0.549 -0.563 -0.159 0.387 0.596 0.000 0.141 -0.116 0.591 0.969 0.523 -0.332 0.050 -0.358 0.485 0.478 0.906 -0.440 0.436 -0.103 -0.586 -0.235 - 0.709 0.000 0.187 0.007 0.111 0.001 0.257 0.195 0.286 0.298 Rb 0.046 0.586 0.318 0.186 -0.576 -0.725 0.685 0.423 0.077 0.818 0.810 0.013 -0.323 0.443 -0.430 -0.285 -0.531 -0.218 0.276 0.063 0.008 -0.837 0.156 -0.149 -0.430 -0.135 - 0.774 0.509 0.887 0.663 0.941 0.301 0.374 0.650 0.758 S -0.720 -0.149 0.942 0.750 -0.819 -0.219 0.539 0.856 -0.128 0.451 0.185 0.786 0.812 0.756 -0.611 0.191 -0.434 0.624 0.709 0.964 -0.473 0.151 -0.057 -0.510 -0.300 0.905 0.104 - 0.130 0.000 0.011 0.017 0.380 0.241 0.051 0.209 Sc 0.393 -0.042 -0.625 -0.705 0.509 0.142 -0.392 -0.478 0.048 -0.439 -0.207 -0.449 -0.420 -0.457 0.245 -0.130 0.305 -0.093 -0.501 -0.575 0.650 -0.155 -0.239 0.088 0.167 -0.455 -0.237 -0.512 - 0.191 0.320 0.031 0.302 0.819 0.195 0.649 Sn -0.875 -0.369 0.911 0.833 -0.826 -0.074 0.454 0.912 -0.265 0.494 0.273 0.902 0.705 0.806 -0.756 0.396 -0.404 0.812 0.817 0.900 -0.573 0.107 -0.078 -0.391 -0.258 0.786 0.052 0.943 -0.450 - 0.001 0.044 0.346 0.073 0.004 0.154 Sr -0.944 -0.536 0.831 0.771 -0.831 0.009 0.542 0.906 -0.649 0.668 0.271 0.974 0.400 0.930 -0.679 0.667 -0.373 0.885 0.954 0.780 -0.554 -0.039 0.288 -0.220 0.089 0.536 0.158 0.757 -0.351 0.871 - 0.224 0.141 0.215 0.000 0.486 Th -0.392 0.011 0.688 0.597 -0.496 -0.170 0.373 0.506 0.030 0.213 -0.010 0.493 0.856 0.461 -0.288 0.031 -0.371 0.341 0.468 0.779 -0.673 0.407 -0.024 -0.455 -0.279 0.866 -0.027 0.729 -0.679 0.645 0.423 - 0.206 0.197 0.274 0.428 V -0.552 -0.654 0.397 0.479 -0.122 0.590 0.009 0.241 -0.772 0.094 -0.494 0.581 0.368 0.358 0.072 0.764 0.229 0.470 0.559 0.535 -0.422 0.574 0.677 0.199 0.698 0.396 -0.364 0.312 -0.363 0.334 0.500 0.437 - 0.820 0.177 0.779 Y 0.475 0.406 -0.280 -0.346 0.243 -0.116 0.051 -0.377 0.012 0.039 -0.117 -0.453 -0.509 -0.267 0.551 -0.233 0.244 -0.703 -0.325 -0.334 0.449 -0.230 0.473 0.307 0.309 -0.447 0.316 -0.408 -0.083 -0.590 -0.430 -0.445 -0.083 - 0.185 0.244 Zn -0.947 -0.581 0.749 0.830 -0.771 0.092 0.449 0.858 -0.633 0.681 0.363 0.945 0.269 0.870 -0.721 0.721 -0.316 0.851 0.944 0.654 -0.654 -0.066 0.272 -0.074 0.059 0.375 0.164 0.630 -0.447 0.811 0.946 0.384 0.464 -0.456 - 0.489 Zr 0.416 0.298 -0.386 -0.574 0.203 -0.285 0.345 -0.395 -0.056 -0.058 -0.269 -0.366 -0.358 -0.070 0.453 -0.204 -0.015 -0.386 -0.345 -0.380 0.405 0.031 0.448 -0.302 0.351 -0.366 0.112 -0.435 0.165 -0.487 -0.250 -0.283 -0.102 0.406 -0.248 - 142 d) Ferrara WtE plant FERRARA Grain size SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI As Ba Ce Cl Co Cr Cu Ga Hf La Mo Nb Nd Ni Pb Rb S Sc Sn Sr Th V Y Zn Zr Grain size - 0,902 0,602 0,851 0,977 0,770 0,852 0,857 0,888 0,786 0,522 0,894 0,323 0,250 0,276 0,213 0,224 0,270 0,216 0,240 0,364 0,653 0,201 0,209 0,750 0,267 0,383 0,184 0,254 0,141 0,388 0,269 0,361 0,219 0,203 0,350 0,208 SiO2 -0,045 - 1E-06 2E-10 1E-09 1E-07 2E-10 4E-10 8E-06 8E-06 2E-06 1E-09 0,004 0,020 0,014 0,046 0,034 0,013 0,043 0,024 0,043 5E-06 0,063 0,060 0,000 0,014 0,001 0,094 0,019 0,325 0,001 0,014 0,001 0,040 0,095 0,003 0,053 TiO2 -0,189 0,976 - 3E-06 3E-06 8E-08 5E-07 4E-06 0,000 1E-05 5E-07 8E-06 0,001 0,008 0,005 0,020 0,014 0,005 0,018 0,009 0,027 4E-06 0,028 0,027 0,000 0,005 0,000 0,045 0,007 0,191 0,000 0,005 0,000 0,017 0,046 0,001 0,024 Al2O3 -0,068 0,997 0,972 - 8E-08 4E-07 1E-10 2E-15 2E-06 3E-06 6E-07 5E-11 0,003 0,018 0,012 0,041 0,030 0,011 0,038 0,021 0,041 2E-06 0,058 0,054 0,000 0,012 0,001 0,086 0,016 0,306 0,001 0,012 0,001 0,036 0,086 0,002 0,048 Fe2O3 0,010 0,996 0,972 0,988 - 1E-07 1E-08 1E-07 2E-05 1E-05 1E-05 1E-07 0,005 0,024 0,017 0,052 0,039 0,016 0,048 0,028 0,044 1E-05 0,070 0,067 0,000 0,017 0,002 0,104 0,022 0,344 0,002 0,016 0,001 0,046 0,103 0,003 0,060 MnO -0,106 0,988 0,988 0,982 0,987 - 1E-07 6E-07 0,000 2E-05 1E-06 1E-06 0,003 0,015 0,011 0,035 0,026 0,010 0,033 0,018 0,038 8E-06 0,048 0,046 0,000 0,010 0,001 0,074 0,014 0,270 0,001 0,010 0,001 0,031 0,075 0,002 0,041 MgO -0,068 0,998 0,981 0,998 0,992 0,986 - 3E-10 8E-06 9E-07 5E-07 3E-09 0,003 0,018 0,012 0,040 0,030 0,011 0,038 0,021 0,041 3E-06 0,057 0,053 0,000 0,012 0,001 0,085 0,016 0,303 0,001 0,012 0,001 0,035 0,085 0,002 0,047 CaO -0,066 0,997 0,969 1,000 0,987 0,980 0,997 - 2E-06 3E-06 7E-07 7E-12 0,004 0,020 0,014 0,045 0,034 0,013 0,042 0,023 0,044 4E-06 0,063 0,059 0,000 0,014 0,001 0,093 0,018 0,324 0,001 0,013 0,001 0,040 0,093 0,002 0,053 Na2O 0,051 0,963 0,902 0,973 0,952 0,919 0,963 0,974 - 4E-05 0,000 3E-06 0,006 0,025 0,017 0,052 0,041 0,017 0,049 0,029 0,041 3E-05 0,073 0,067 0,001 0,017 0,002 0,102 0,023 0,333 0,002 0,017 0,002 0,046 0,099 0,004 0,060 K2O -0,099 0,962 0,960 0,971 0,957 0,953 0,978 0,971 0,945 - 2E-06 6E-06 0,004 0,017 0,012 0,037 0,028 0,011 0,035 0,019 0,043 1E-05 0,052 0,048 0,001 0,011 0,001 0,076 0,015 0,273 0,001 0,011 0,001 0,033 0,073 0,002 0,043 P2O5 -0,230 0,972 0,982 0,981 0,958 0,978 0,981 0,980 0,929 0,976 - 2E-06 0,001 0,008 0,006 0,021 0,015 0,005 0,019 0,010 0,030 2E-06 0,031 0,029 0,001 0,005 0,000 0,048 0,008 0,201 0,000 0,005 0,000 0,018 0,049 0,001 0,025 LOI -0,049 0,996 0,963 0,998 0,987 0,978 0,995 0,999 0,971 0,965 0,974 - 0,007 0,030 0,021 0,063 0,048 0,020 0,059 0,034 0,061 1E-05 0,086 0,081 0,001 0,021 0,002 0,123 0,027 0,392 0,002 0,020 0,002 0,056 0,124 0,004 0,073 As -0,349 0,814 0,862 0,823 0,801 0,828 0,823 0,815 0,794 0,820 0,861 0,788 - 9E-08 9E-09 5E-06 1E-06 6E-09 4E-06 2E-07 6E-05 9E-05 2E-05 1E-05 5E-05 8E-09 1E-09 7E-05 6E-08 0,003 4E-09 7E-09 2E-08 3E-06 7E-05 2E-12 9E-06 Ba -0,402 0,714 0,779 0,725 0,701 0,736 0,726 0,716 0,699 0,730 0,776 0,683 0,988 - 2E-12 3E-09 8E-11 5E-12 1E-09 4E-15 1E-05 0,001 7E-08 4E-08 0,000 2E-12 4E-06 8E-07 9E-18 0,000 5E-06 4E-12 1E-05 6E-10 9E-07 6E-07 1E-08 Ce -0,382 0,741 0,801 0,752 0,728 0,761 0,752 0,743 0,726 0,755 0,799 0,711 0,993 0,999 - 4E-08 4E-09 9E-17 2E-08 4E-11 1E-05 0,001 4E-07 3E-07 0,000 8E-17 9E-07 3E-06 3E-13 0,001 2E-06 5E-17 3E-06 1E-08 4E-06 1E-07 1E-07 Cl -0,432 0,641 0,717 0,653 0,629 0,668 0,654 0,643 0,628 0,662 0,712 0,607 0,968 0,995 0,990 - 1E-12 5E-08 8E-18 5E-10 9E-06 0,005 2E-11 2E-12 0,002 4E-08 5E-05 4E-09 5E-09 5E-05 7E-05 5E-08 0,000 2E-15 6E-09 1E-05 1E-14 Co -0,423 0,670 0,743 0,680 0,657 0,695 0,682 0,670 0,652 0,688 0,737 0,636 0,976 0,998 0,995 0,999 - 5E-09 2E-13 6E-12 9E-06 0,003 8E-10 3E-10 0,001 4E-09 2E-05 5E-08 2E-10 0,000 3E-05 5E-09 5E-05 2E-14 6E-08 5E-06 4E-11 Cr -0,387 0,745 0,805 0,756 0,732 0,765 0,756 0,747 0,729 0,758 0,803 0,715 0,994 0,999 1,000 0,990 0,994 - 3E-08 7E-11 2E-05 0,001 5E-07 3E-07 0,000 3E-20 8E-07 4E-06 9E-13 0,001 1E-06 2E-23 2E-06 2E-08 4E-06 7E-08 2E-07 Cu -0,429 0,648 0,722 0,659 0,635 0,674 0,660 0,649 0,634 0,668 0,718 0,614 0,970 0,996 0,991 1,000 1,000 0,991 - 2E-10 9E-06 0,004 6E-11 8E-12 0,001 3E-08 4E-05 8E-09 3E-09 6E-05 6E-05 3E-08 8E-05 6E-18 1E-08 1E-05 2E-13 Ga -0,410 0,702 0,769 0,713 0,689 0,725 0,713 0,703 0,686 0,718 0,765 0,670 0,985 1,000 0,998 0,997 0,999 0,998 0,997 - 1E-05 0,002 2E-08 1E-08 0,001 4E-11 6E-06 4E-07 8E-14 0,000 9E-06 6E-11 2E-05 9E-11 5E-07 1E-06 3E-09 Hf -0,322 0,648 0,692 0,653 0,646 0,661 0,652 0,644 0,651 0,647 0,682 0,610 0,938 0,960 0,957 0,961 0,962 0,956 0,962 0,960 - 0,005 9E-06 1E-05 0,001 1E-05 2E-04 2E-05 1E-05 0,001 0,000 2E-05 0,000 9E-06 2E-05 1E-04 1E-05 La -0,163 0,966 0,969 0,972 0,958 0,962 0,972 0,969 0,948 0,958 0,974 0,957 0,931 0,863 0,883 0,809 0,830 0,885 0,814 0,854 0,800 - 0,008 7E-03 1E-05 0,001 1E-05 0,014 0,001 0,089 7E-06 0,001 5E-06 0,004 0,014 4E-05 0,006 Mo -0,442 0,606 0,688 0,616 0,595 0,636 0,618 0,606 0,589 0,627 0,678 0,568 0,954 0,989 0,982 0,999 0,996 0,981 0,998 0,991 0,961 0,780 - 2E-13 0,003 5E-07 0,000 9E-11 1E-07 2E-05 0,000 5E-07 0,000 1E-10 3E-10 5E-05 8E-13 Nb -0,435 0,612 0,691 0,624 0,600 0,640 0,625 0,613 0,600 0,637 0,685 0,576 0,957 0,990 0,984 0,999 0,997 0,983 0,999 0,993 0,959 0,787 1,000 - 0,002 3E-07 0,000 1E-10 6E-08 2E-05 0,000 3E-07 0,000 3E-11 2E-10 4E-05 9E-15 Nd -0,116 0,905 0,911 0,900 0,910 0,909 0,903 0,895 0,881 0,876 0,891 0,876 0,942 0,896 0,910 0,856 0,872 0,912 0,860 0,889 0,886 0,959 0,837 0,840 - 0,000 1E-05 0,005 0,000 0,040 1E-05 0,000 2E-05 0,001 0,0048 3E-05 0,002 Ni -0,388 0,743 0,803 0,753 0,730 0,763 0,754 0,744 0,726 0,756 0,801 0,713 0,994 0,999 1,000 0,990 0,994 1,000 0,991 0,998 0,957 0,884 0,982 0,984 0,911 - 9E-07 4E-06 4E-13 0,001 1E-06 3E-21 3E-06 2E-08 4E-06 9E-08 1E-07 Pb -0,310 0,863 0,900 0,872 0,851 0,873 0,871 0,865 0,844 0,865 0,901 0,841 0,996 0,969 0,978 0,940 0,952 0,980 0,943 0,965 0,916 0,960 0,923 0,927 0,958 0,979 - 0,000 3E-06 0,009 2E-16 8E-07 2E-11 4E-05 0,000 1E-11 8E-05 Rb -0,457 0,557 0,642 0,570 0,545 0,588 0,571 0,559 0,547 0,585 0,636 0,520 0,936 0,979 0,970 0,994 0,990 0,969 0,994 0,983 0,952 0,743 0,998 0,998 0,804 0,970 0,899 - 1E-06 3E-06 0,000 4E-06 0,001 1E-08 3E-13 0,000 7E-10 S -0,399 0,720 0,784 0,731 0,707 0,742 0,732 0,722 0,705 0,735 0,781 0,689 0,989 1,000 0,999 0,994 0,997 0,999 0,995 1,000 0,959 0,868 0,988 0,989 0,900 0,999 0,972 0,977 - 0,000 4E-06 6E-13 7E-06 1E-09 1E-06 4E-07 2E-08 Sc -0,501 0,348 0,451 0,361 0,335 0,386 0,363 0,348 0,342 0,384 0,442 0,305 0,827 0,904 0,886 0,942 0,929 0,883 0,939 0,911 0,891 0,565 0,956 0,954 0,654 0,885 0,771 0,972 0,900 - 0,010 0,001 0,012 7E-05 3E-06 0,005 3E-05 Sn -0,307 0,869 0,905 0,878 0,857 0,879 0,877 0,872 0,850 0,870 0,907 0,848 0,994 0,966 0,976 0,936 0,948 0,977 0,939 0,961 0,912 0,964 0,918 0,922 0,960 0,976 1,000 0,894 0,968 0,763 - 1E-06 5E-12 5E-05 0,001 9E-11 0,000 Sr -0,387 0,744 0,804 0,754 0,731 0,764 0,755 0,746 0,728 0,757 0,802 0,714 0,994 0,999 1,000 0,990 0,994 1,000 0,991 0,998 0,956 0,885 0,982 0,984 0,911 1,000 0,979 0,969 0,999 0,884 0,977 - 3E-06 2E-08 4E-06 8E-08 1E-07 Th -0,324 0,876 0,916 0,885 0,862 0,887 0,885 0,879 0,850 0,878 0,917 0,856 0,992 0,961 0,971 0,929 0,942 0,972 0,932 0,956 0,897 0,966 0,911 0,914 0,953 0,972 0,999 0,885 0,963 0,752 0,999 0,972 - 7E-05 0,001 1E-09 0,000 V -0,427 0,654 0,728 0,666 0,641 0,680 0,666 0,656 0,640 0,674 0,723 0,620 0,972 0,997 0,992 1,000 1,000 0,992 1,000 0,998 0,962 0,819 0,998 0,998 0,863 0,992 0,946 0,993 0,996 0,936 0,941 0,992 0,93522 - 2E-08 9E-06 1E-12 Y -0,441 0,557 0,640 0,569 0,546 0,587 0,571 0,558 0,550 0,589 0,635 0,519 0,935 0,978 0,970 0,994 0,989 0,968 0,993 0,982 0,955 0,744 0,997 0,997 0,807 0,969 0,899 0,999 0,977 0,971 0,893 0,969 0,88388 0,99 - 0,0002 1E-09 Zn -0,331 0,836 0,879 0,845 0,823 0,848 0,845 0,838 0,818 0,841 0,879 0,812 0,999 0,981 0,988 0,957 0,967 0,989 0,959 0,977 0,930 0,945 0,941 0,945 0,950 0,988 0,999 0,921 0,983 0,803 0,998 0,988 0,99578 0,96 0,920 - 3E-05 Zr -0,436 0,625 0,702 0,637 0,612 0,652 0,638 0,626 0,612 0,647 0,697 0,590 0,962 0,993 0,987 1,000 0,998 0,986 1,000 0,995 0,961 0,796 0,999 1,000 0,846 0,987 0,933 0,996 0,992 0,949 0,928 0,986 0,92111 1,00 0,996 0,95021 - 143 e) Forlì WtE plant FORLÌ Grain size SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI As Ba Ce Cl Co Cr Cu Ga Hf La Mo Nb Nd Ni Pb Rb S Sc Sn Sr Th V Y Zn Zr Grain size - 2E-05 0,696 0,225 0,0424 0,209 0,338 0,001 0,025 0,029 0,230 0,000 0,113 0,887 0,016 0,271 0,008 0,228 0,053 0,157 0,814 0,347 0,137 0,192 0,416 0,091 0,157 0,031 0,0052 0,208 4E-05 4E-05 0,097 0,675 0,698 0,000 0,006 SiO2 0,969 - 0,655 0,190 0,0443 0,153 0,273 0,000 0,022 0,011 0,201 0,000 0,080 0,815 0,012 0,179 0,024 0,175 0,014 0,117 0,722 0,371 0,087 0,150 0,465 0,180 0,111 0,013 0,0011 0,326 1E-06 1E-05 0,053 0,653 0,687 0,001 0,002 TiO2 -0,152 -0,173 - 0,497 0,1059 0,001 0,113 0,173 0,072 0,921 0,001 0,481 0,006 4E-06 0,138 0,571 0,620 0,000 0,776 0,002 0,206 0,206 0,008 0,081 0,233 0,513 0,008 0,031 0,1927 0,725 0,477 0,775 0,019 0,003 6E-06 0,297 0,734 Al2O3 0,449 0,481 0,261 - 0,0670 0,919 0,100 0,334 0,830 0,002 0,806 0,447 0,831 0,638 0,947 0,873 0,718 0,913 0,213 0,731 0,499 0,487 0,519 0,015 0,569 0,820 0,842 0,434 0,3658 0,112 0,247 0,158 0,707 0,233 0,581 0,712 0,209 Fe2O3 0,683 0,679 0,574 0,634 - 0,609 0,006 0,276 0,832 0,033 0,516 0,153 0,868 0,084 0,536 0,580 0,318 0,487 0,088 0,700 0,405 0,872 0,878 0,001 0,973 0,646 0,837 0,741 0,2869 0,637 0,104 0,046 0,936 0,009 0,119 0,254 0,011 MnO 0,464 0,518 -0,894 -0,040 -0,1983 - 0,621 0,011 0,022 0,434 0,000 0,134 1E-06 0,003 0,009 0,256 0,443 2E-06 0,626 0,000 0,207 0,191 0,001 0,473 0,165 0,522 6E-06 0,001 0,0108 0,678 0,101 0,274 5E-05 0,112 0,001 0,059 0,469 MgO 0,362 0,410 0,564 0,583 0,8289 -0,192 - 0,557 0,492 0,060 0,506 0,720 0,861 0,166 0,760 0,808 0,761 0,400 0,372 0,665 0,963 0,880 0,830 0,011 0,850 0,899 0,956 0,942 0,5009 0,756 0,484 0,430 0,882 0,001 0,153 0,824 0,046 CaO -0,897 -0,926 0,498 -0,365 -0,4080 -0,789 -0,227 - 0,005 0,033 0,017 0,001 0,003 0,245 0,001 0,151 0,063 0,016 0,085 0,007 0,743 0,233 0,008 0,480 0,253 0,195 0,006 0,000 9E-06 0,285 0,000 0,003 0,002 0,797 0,168 0,000 0,021 Na2O 0,731 0,742 -0,625 0,084 0,0832 0,741 -0,264 -0,836 - 0,332 0,023 0,002 0,021 0,171 0,008 0,080 0,018 0,010 0,100 0,019 0,706 0,199 0,037 0,971 0,747 0,171 0,049 0,007 0,0070 0,157 0,004 0,016 0,040 0,233 0,097 0,001 0,186 K2O 0,718 0,791 0,039 0,879 0,7080 0,299 0,647 -0,707 0,367 - 0,560 0,083 0,253 0,999 0,239 0,519 0,365 0,488 0,043 0,252 0,758 0,990 0,152 0,028 0,346 0,534 0,259 0,069 0,0409 0,247 0,024 0,019 0,157 0,310 0,981 0,168 0,019 P2O5 -0,445 -0,470 0,914 0,096 0,2504 -0,991 0,256 0,760 -0,740 -0,225 - 0,154 8E-06 0,002 0,009 0,306 0,414 4E-06 0,769 3E-05 0,161 0,178 0,002 0,366 0,163 0,453 0,000 0,002 0,0200 0,593 0,129 0,330 0,000 0,082 0,000 0,065 0,554 LOI -0,940 -0,947 0,271 -0,291 -0,5180 -0,540 -0,140 0,893 -0,875 -0,607 0,517 - 0,083 0,708 0,007 0,162 0,002 0,121 0,014 0,109 0,578 0,348 0,120 0,367 0,627 0,126 0,133 0,018 0,0038 0,225 5E-06 4E-05 0,077 0,952 0,518 0,000 0,014 As 0,565 0,612 -0,828 0,084 -0,0648 0,986 -0,069 -0,858 0,745 0,426 -0,975 -0,608 - 0,009 0,004 0,289 0,358 0,000 0,503 3E-06 0,199 0,231 0,000 0,673 0,110 0,443 0,000 0,000 0,0040 0,550 0,052 0,171 2E-06 0,212 0,004 0,036 0,303 Ba -0,056 -0,091 0,979 0,183 0,6062 -0,865 0,505 0,433 -0,499 0,000 0,878 0,146 -0,805 - 0,233 0,760 0,901 0,001 0,640 0,003 0,131 0,308 0,007 0,084 0,160 0,654 0,008 0,043 0,2687 0,781 0,648 0,973 0,022 0,006 0,000 0,503 0,619 Ce 0,766 0,788 -0,535 0,026 0,2387 0,803 0,119 -0,906 0,813 0,437 -0,801 -0,821 0,844 -0,443 - 0,109 0,110 0,017 0,149 0,015 0,538 0,113 0,052 0,865 0,493 0,211 0,007 0,006 0,0010 0,523 0,006 0,041 0,005 0,705 0,121 0,001 0,030 Cl -0,412 -0,492 0,219 -0,063 -0,2141 -0,423 -0,095 0,521 -0,612 -0,249 0,385 0,509 -0,398 0,119 -0,570 - 0,652 0,281 0,161 0,387 0,379 0,203 0,427 0,325 0,229 0,994 0,358 0,242 0,0461 0,643 0,134 0,208 0,331 0,947 0,680 0,128 0,146 Co -0,811 -0,734 0,192 -0,141 -0,3762 -0,294 0,119 0,641 -0,759 -0,344 0,312 0,871 -0,349 0,049 -0,569 0,175 - 0,337 0,115 0,347 0,465 0,447 0,360 0,746 0,635 0,027 0,489 0,167 0,1530 0,169 0,013 0,006 0,396 0,694 0,685 0,005 0,175 Cr 0,447 0,496 -0,931 -0,043 -0,2675 0,984 -0,321 -0,765 0,798 0,267 -0,979 -0,555 0,960 -0,893 0,762 -0,404 -0,363 - 0,591 8E-06 0,328 0,202 0,000 0,394 0,202 0,434 0,000 0,001 0,0185 0,524 0,103 0,259 0,001 0,049 0,000 0,060 0,585 Cu 0,660 0,775 0,111 0,460 0,5990 0,189 0,339 -0,604 0,582 0,682 -0,115 -0,776 0,258 0,182 0,522 -0,509 -0,563 0,208 - 0,535 0,113 0,878 0,509 0,082 0,682 0,567 0,587 0,179 0,0701 0,419 0,013 0,009 0,391 0,461 0,718 0,057 0,010 Ga 0,514 0,560 -0,871 0,134 -0,1500 0,973 -0,168 -0,819 0,752 0,427 -0,964 -0,571 0,982 -0,861 0,771 -0,329 -0,356 0,975 0,240 - 0,251 0,284 0,000 0,584 0,099 0,394 1E-05 0,000 0,0111 0,397 0,072 0,199 6E-05 0,121 0,001 0,062 0,439 Hf 0,092 0,139 0,466 0,260 0,3179 -0,465 -0,018 0,128 0,147 0,120 0,509 -0,215 -0,472 0,543 -0,238 -0,334 -0,281 -0,369 0,565 -0,428 - 0,729 0,372 0,165 0,038 0,978 0,128 0,560 0,8501 0,501 0,677 0,415 0,207 0,524 0,113 0,880 0,658 La 0,356 0,340 -0,466 -0,267 -0,0631 0,480 -0,059 -0,443 0,473 -0,005 -0,492 -0,355 0,444 -0,383 0,565 -0,469 -0,291 0,470 0,060 0,402 -0,135 - 0,257 0,676 0,797 0,052 0,249 0,270 0,2302 0,835 0,331 0,525 0,283 0,567 0,342 0,192 0,385 Mo 0,536 0,600 -0,814 0,249 -0,0601 0,915 -0,084 -0,809 0,698 0,520 -0,879 -0,556 0,925 -0,817 0,662 -0,304 -0,347 0,920 0,254 0,951 -0,339 0,422 - 0,772 0,079 0,371 0,001 9E-05 0,0125 0,526 0,067 0,151 0,000 0,172 0,012 0,081 0,444 Nb 0,479 0,521 0,610 0,772 0,8911 -0,276 0,791 -0,271 0,014 0,721 0,343 -0,343 -0,164 0,606 0,067 -0,372 -0,126 -0,325 0,608 -0,212 0,506 -0,163 -0,113 - 0,554 0,915 0,642 0,902 0,3864 0,451 0,236 0,132 0,832 0,009 0,089 0,578 0,041 Nd -0,310 -0,280 0,442 -0,220 -0,0131 -0,505 -0,074 0,426 -0,126 -0,356 0,507 0,189 -0,568 0,511 -0,264 -0,446 0,184 -0,469 0,159 -0,583 0,695 0,100 -0,614 0,228 - 0,654 0,087 0,148 0,4389 0,859 0,528 0,603 0,083 0,503 0,157 0,551 0,979 Ni -0,595 -0,490 0,252 -0,089 -0,1784 -0,247 0,050 0,476 -0,500 -0,240 0,288 0,549 -0,294 0,174 -0,462 -0,003 0,727 -0,299 -0,222 -0,325 -0,011 -0,662 -0,340 0,042 0,174 - 0,505 0,304 0,3942 0,321 0,149 0,168 0,508 0,711 0,598 0,118 0,308 Pb 0,514 0,567 -0,814 0,078 -0,0806 0,977 -0,022 -0,824 0,669 0,421 -0,964 -0,540 0,993 -0,809 0,821 -0,348 -0,266 0,938 0,211 0,971 -0,547 0,429 0,911 -0,181 -0,600 -0,257 - 0,000 0,0076 0,662 0,084 0,243 1E-06 0,250 0,004 0,065 0,324 Rb 0,712 0,779 -0,712 0,299 0,1291 0,911 0,028 -0,937 0,822 0,630 -0,874 -0,757 0,947 -0,682 0,829 -0,435 -0,504 0,908 0,491 0,947 -0,225 0,412 0,949 0,048 -0,524 -0,386 0,923 - 0,0005 0,374 0,007 0,034 6E-05 0,349 0,034 0,012 0,142 S -0,834 -0,896 0,478 -0,343 -0,3994 -0,793 -0,259 0,974 -0,819 -0,687 0,750 0,849 -0,847 0,413 -0,897 0,675 0,518 -0,756 -0,628 -0,791 0,074 -0,445 -0,783 -0,330 0,296 0,325 -0,814 -0,915 - 0,386 0,001 0,007 0,003 0,877 0,198 0,002 0,018 Sc 0,464 0,371 -0,137 0,566 0,1834 0,161 -0,121 -0,401 0,513 0,431 -0,207 -0,449 0,231 -0,108 0,246 -0,180 -0,501 0,245 0,309 0,323 0,259 -0,082 0,244 0,289 -0,069 -0,374 0,170 0,338 -0,330 - 0,207 0,179 0,719 0,740 0,580 0,336 0,564 Sn -0,961 -0,985 0,273 -0,431 -0,5762 -0,580 -0,269 0,945 -0,841 -0,737 0,545 0,978 -0,661 0,177 -0,830 0,540 0,783 -0,579 -0,779 -0,625 -0,162 -0,367 -0,634 -0,440 0,244 0,522 -0,606 -0,817 0,914 -0,465 - 1E-05 0,042 0,906 0,502 0,000 0,005 Sr -0,959 -0,971 0,112 -0,513 -0,6762 -0,409 -0,302 0,859 -0,767 -0,755 0,368 0,960 -0,500 0,013 -0,686 0,464 0,824 -0,421 -0,805 -0,472 -0,311 -0,245 -0,520 -0,542 0,202 0,503 -0,434 -0,705 0,817 -0,492 0,973 - 0,141 0,723 0,824 0,001 0,009 Th 0,587 0,660 -0,753 0,146 0,0314 0,958 0,058 -0,871 0,689 0,514 -0,926 -0,616 0,984 -0,744 0,832 -0,367 -0,323 0,917 0,326 0,955 -0,465 0,402 0,927 -0,083 -0,607 -0,255 0,986 0,955 -0,863 0,140 -0,683 -0,532 - 0,347 0,016 0,039 0,216 V 0,163 0,175 0,860 0,443 0,8067 -0,567 0,894 0,101 -0,443 0,382 0,609 0,023 -0,461 0,829 -0,147 -0,026 0,153 -0,668 0,283 -0,555 0,246 -0,221 -0,499 0,804 0,258 0,144 -0,429 -0,355 0,060 -0,130 -0,046 -0,138 -0,356 - 0,007 0,783 0,151 Y -0,151 -0,157 0,977 0,214 0,5571 -0,895 0,519 0,502 -0,587 0,009 0,928 0,249 -0,848 0,971 -0,555 0,160 0,158 -0,920 0,141 -0,888 0,564 -0,360 -0,786 0,597 0,514 0,204 -0,844 -0,705 0,473 -0,214 0,259 0,087 -0,768 0,818 - 0,329 0,755 Zn -0,922 -0,915 0,392 -0,144 -0,4251 -0,647 -0,087 0,917 -0,894 -0,503 0,636 0,975 -0,699 0,258 -0,895 0,546 0,833 -0,646 -0,652 -0,642 -0,059 -0,479 -0,609 -0,215 0,231 0,559 -0,637 -0,789 0,880 -0,363 0,951 0,898 -0,693 0,107 0,369 - 0,024 Zr 0,827 0,877 0,132 0,463 0,7944 0,278 0,675 -0,747 0,485 0,753 -0,229 -0,776 0,387 0,193 0,718 -0,526 -0,496 0,212 0,796 0,296 0,172 0,330 0,293 0,687 -0,010 -0,384 0,372 0,531 -0,758 0,223 -0,832 -0,805 0,458 0,521 0,122 -0,735 - 144 APPENDIX VIII XRF results analysed by PCA for 5 WtE investigated. a) Parma WtE plant 145 b) Piacenza WtE plant 146 c) Torino WtE plant 147 d) Ferrara WtE plant 148 e) Forlì WtE plants