applied
sciences
Re iew
Ino ganic Was e Gene a ed in K a Pulp Mills:
The T ansi ion om Land ill o
Indus ial Applica ions
Ma ga ida J. Quina * and Ca olina T. Pinhei o
CIEPQPF, Chemical P ocess Enginee ing and Fo es P oduc s Resea ch Cen e,
Depa men o Chemical Enginee ing, Facul y o Sciences and Technology, Uni e si y o Coimb a,
Rua Síl io Lima, Polo II, 3030-790 Coimb a, Po ugal; [email p o ec ed]
*Co espondence: [email p o ec ed]; Tel.: +351-239798700
Recei ed: 29 Feb ua y 2020; Accep ed: 26 Ma ch 2020; Published: 28 Ma ch 2020


Abs ac :
K a pulp mills p oduce he main aw ma e ial o pape , while se e al was e p oduc s a e
gene a ed in la ge quan i ies in he p ocess. This e iew s udy add esses ou o he main ino ganic
was es o med by his indus y, namely g een liquo d egs (GLD), slake g i s (SG), lime mud (LM)
and boile ly ash (BFA), which a e s ill mos ly disca ded in land ills. A b ie o e iew o a ypical
indus ial p ocess was included o ou line he was e gene a ion poin s. The main chemical and
physical p ope ies a e indica ed o highligh ing he mos ele an cha ac e is ics o de e mine
which applica ions may be conside ed in each case. An in-dep h li e a u e e iew allowed he
iden i ica ion o he main applica ions ha ha e been es ed mainly a he labo a o y scale and
some a an indus ial scale. The applica ions a e g ouped in o cons uc ion ma e ials, geo echnical,
en i onmen al, ag icul u al and o he s. This assessmen shows ha he ci cula economy and he
sus ainable de elopmen goals o he UN a e impo an issues o o ganiza ions in gene al, and he
pulp mill in pa icula . In ac , his indus y has managed o close he chemicals loops, eco e ene gy
and educe wa e consump ion in he p ocess. Howe e , he cu en si ua ion o ino ganic was e can
s ill be imp o ed i indus ial applica ions a e de eloped o a oid land ill.
Keywo ds: g een liquo d egs; slake g i s; lime mud; boile ly ash; ecycling; k a pulp mills
1. In oduc ion
Acco ding o he Con ede a ion o Eu opean Pape Indus ies (CEPI), which ep esen s nea ly
151 pulp mills om Eu ope, in 2018, abou 154.9 M o wood (42.8 M o ha dwood and 112.1 M
o so wood) was consumed and 38.3 M o pulp was p oduced [
1
]. Sweden, Finland, and Po ugal
a e he op h ee coun ies, accoun ing o 68.6% o he pulp p oduc ion. The Eu opean coun ies
p oduce 25.3% o wo ld pulp p oduc ion (184.4 M in 2017), which accoun s o a o al pape and boa d
p oduc ion o 92.2 M . Indeed, he pulp and pape indus y is one o he la ges indus ies in he wo ld,
wi h a e y signi ican con ibu ion o he economy o many coun ies (e.g., Sweden, Finland, Po ugal,
Ge many, Spain, F ance, and Poland). Al hough he Eu opean Commission adop ed an ambi ious
Ci cula Economy Ac ion Plan in 2015 [
2
], he e is po en ial o mo e ecycling o pape , wi h bo h
en i onmen al and economic bene i s, including less wood u iliza ion o pulp p oduc ion.
The main aw ma e ials o pulp p oduc ion a e wood, a ious chemicals, and wa e , while
signi ican amoun s o was e a e also gene a ed. Indeed, besides he impac associa ed wi h wood
consump ion, pulp mills gene a e la ge amoun s o solid, liquid and gaseous emissions, equi ing
ea men be o e being eleased in o he en i onmen [
3
]. This s udy is ocused on he main ino ganic
solid was es ha equi e an en i onmen ally iendly solu ion: g een liquo d egs (GLD), slake
Appl. Sci. 2020,10, 2317; doi:10.3390/app10072317 www.mdpi.com/jou nal/applsci
Appl. Sci. 2020,10, 2317 2 o 20
g i s (SG), lime mud (LM) and boile ly ash (BFA). These was es ha e been p oduced in high
quan i ies, and land ill has been he main disposal me hod [
4
,
5
]. Acco ding o he EU Lis o Was e
(Commission Decision 2014/955/EU), he assignmen o codes o GLD is 03 03 02, SG 03 03 09, LM 03
03 09 and BFA 10 01 01, all o hem classi ied as non-haza dous was e. The cu en en i onmen al
policies (Was e F amewo k Di ec i e 2008/98/EC) sugges ha he disposal o ma e ials in land ill
mus be minimized and a clea ecommenda ion is made o ce ain was e o cease o be was e. Fo
ha , end-o -was e (EoW) c i e ia should be de eloped, in pa icula , i —i) ma e ial is commonly used
o speci ic pu poses; ii) he e is an exis ing ma ke o demand; iii) he ma e ial ul ills he echnical
equi emen s o he speci ic pu poses; i ) he use does no lead o ad e se impac s on he en i onmen
o human heal h. Thus, i would be o in e es o de elop EoW c i e ia o hese was es o minimize he
loss o ha an h opogenic esou ces and o p omo e he de elopmen o applica ions a he indus ial
scale. Fu he mo e, aking in o conside a ion he la ge quan i ies o GLD, SG, LM, and BFA o med,
he de elopmen o p ac ical applica ions could make a aluable con ibu ion o a ci cula economy
agenda, because i ensu es ha he esou ces a e kep in he economy o as long as possible.
The li e a u e e iew o iden i y he main wo ks in he ield was ca ied ou mainly on Web o
Science (WoS), sea ching o “g een liquo d egs” o “slake g i s” o “lime mud” o “boile ly ash”,
combined wi h “pulp mills” in he i le o opic. O he e e ences we e collec ed based on hose o he
main wo ks iden i ied in he WoS. O e all, 90 e e ences we e conside ed in his s udy, wi h 75% o
hose sou ces published om 2010 onwa ds.
In his con ex , he main objec i e o his e iew is o summa ize he p ope ies o he main
ino ganic was es gene a ed in k a pulp mills, highligh ing which esou ces can be eco e ed and
he applica ions which can be implemen ed on an indus ial scale o educe o elimina e he cu en
disposal in land ills. Fo each was e (GLD, SG, LM, and BFA) he main applica ions es ed/used a
he labo a o y o indus ial scale we e iden i ied. The s udy ends wi h u u e pe spec i es o he
use o hese esou ces, emphasizing he main ac o s o selec ing he bes pa hs o an eme ging
ci cula economy.
2. K a Pulp Mill P ocess and he Reco e y o Chemicals
Chemical p ocesses a e he mos common o ob aining pulp o cellulose ibe s, among which
s ands ou he ‘sul a e p ocess’, commonly known as ‘k a p ocess’ due o he high physical-mechanical
esis ance o he pulps p oduced (k a means s eng h in Ge man) and is cu en ly he mos widely
used p ocess in he wo ld (80% o o al chemical pulp) [
6
,
7
]. In his cooking p ocess, wa e -solubilized
eagen s (liquo ) a e added o he wood chips in a eac ion essel (diges e ) o 1 o 3 h a 150–170
◦
C [
8
].
Among he se e al ad an ages compa ed o o he chemical p ocesses, i can be highligh ed he
ollowing [9]:
•Highe s eng h and lexibili y o he p oduced pulps;
•Applicabili y o a ious wood species, ega dless o hei physico-chemical cha ac e is ics;
•The wide ange o pulp applica ions;
•
The e icien eco e y o chemicals used in cooking, o -se ing he high capi al cos s, which makes
i economically mo e iable and compe i i e.
The main ac i e chemicals employed in he k a p ocess a e sodium hyd oxide (NaOH) and
sodium sul ide (Na
2
S), commonly known as whi e liquo . Indeed, he designa ion sul a e p ocess is
due o he addi ion o sodium sul a e o eplace los chemical eagen s. This mix u e leads o lignin
agmen a ion and dissolu ion, while cellulose ibe s a e eleased [
10
]. The cooking eagen s a e no
comple ely selec i e o lignin and he e a e also undesi able eac ions o polysaccha ides, mainly
hemicelluloses, which due o hei chemical s uc u e a e e y suscep ible o chemical a ack. The
cellulose ibe s a e eco e ed om he black liquo , which con ains lignin and aluable chemicals.
Figu e 1shows a simpli ied diag am o he phases o ob ain pulp om wood, highligh ing he cycles
Appl. Sci. 2020,10, 2317 3 o 20
o eco e ing sodium and calcium as well as o ene gy eco e y. In addi ion, he gene a ion poin s o
he was es unde conside a ion (GLD, SK, LM, and BFA) a e also shown in he diag am.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 3 o 21
Figu e 1. The chemical eco e y loops and ene gy gene a ion.
G een liquo d egs (GLD) a e gene a ed du ing he cla i ica ion o g een liquo and con ain he
insoluble ma e ial o he eco e y boile ino ganic lux (smel ). The epo ed GLD suspended solids
con en is abou 600–2000 mg/L and he pH is s ongly alkaline [11,12]. Lime mud (LM) is a by-
p oduc o med du ing he caus icizing eac ion, which is sepa a ed om he whi e liquo , washed
and calcined in he lime kiln, while a ac ion is pu ged as was e and eplaced by esh CaCO
3
. Highe
LM p oduc ion occu s when he e a e di e ences be ween he p oduc ion o whi e liquo and he
p oduc ion capaci y o he lime kiln. The pH o LM can a y sligh ly bu is o en s ongly alkaline
[13]. Slake g i s (SG) a e he coa se ma e ial emo ed om he discha ge o he lime slake o a oid
build-up on caus icize s and mechanical wea on il e componen s [14]. The solids con en o SG is
ypically abou 75% and he pH is usually highe han 12.5 [14,15]. The boile ly ash (BFA) is
gene a ed in a biomass luidized bed boile , as a esul o he combus ion o wood ba k and o he
wood esidues o ene gy eco e y. The used pa icles a e ca ied upwa ds along wi h he lue gas.
As he lue gas app oaches he low- empe a u e zones, he used subs ances solidi y o o m ly ash,
which is cap u ed by cyclones, ab ic il e s and/o elec os a ic p ecipi a o s (ESP) wi h cleaning
e iciency abo e 99% [16]. The ly ash consis s o ine pa icula es and p ecipi a ed ola iles, ypically
wi h a high speci ic su ace a ea [17]. The pH o BFA is ypically alkaline bu lowe han he obse ed
o lime esidues [18].
Closing he loops in k a mills has en i onmen al ad an ages bu leads o he build-up in he
liquo cycle o non-p ocess elemen s (NPE), such as Ca, Mg, K, Mn, Ba, Fe, Al, Ni, Cu, Zn, e c., which
may hinde he pulping, bleaching o chemicals eco e y p ocess. NPE en e he pulping p ocess
h ough he main aw ma e ials, namely wood, make-up chemicals, wa e o may a ise om he
equipmen co osion [19]. In addi ion, he end o closing he wa e cycle accumula es NPE such as
Ca and K in he eco e y cycle. Thei accumula ion may lead o il a ion di icul ies, p ecipi a e
o ma ion, o e en in undesi able ca aly ic e ec s. The pu ge o NPE om he eco e y cycles is
essen ial o main ain no mal ope a ing condi ions. The was es unde analysis, speci ically GLD, SG,
and LM a e o g ea impo ance o he elimina ion o many NPE.
The speci ic p oduc ion o GLD, SG, LM and BFA in k a pulp mills is a iable depending on
he echnology and o he speci ic ac o s in each si e. E en hough, Table 1 shows an o e iew o he
speci ic p oduc ion o each esidue.
Table 1. Speci ic was e gene a ion in k a pulp mills (kg/ AD).
Figu e 1. The chemical eco e y loops and ene gy gene a ion.
G een liquo d egs (GLD) a e gene a ed du ing he cla i ica ion o g een liquo and con ain
he insoluble ma e ial o he eco e y boile ino ganic lux (smel ). The epo ed GLD suspended
solids con en is abou 600–2000 mg/L and he pH is s ongly alkaline [
11
,
12
]. Lime mud (LM) is a
by-p oduc o med du ing he caus icizing eac ion, which is sepa a ed om he whi e liquo , washed
and calcined in he lime kiln, while a ac ion is pu ged as was e and eplaced by esh CaCO
3
. Highe
LM p oduc ion occu s when he e a e di e ences be ween he p oduc ion o whi e liquo and he
p oduc ion capaci y o he lime kiln. The pH o LM can a y sligh ly bu is o en s ongly alkaline [
13
].
Slake g i s (SG) a e he coa se ma e ial emo ed om he discha ge o he lime slake o a oid build-up
on caus icize s and mechanical wea on il e componen s [
14
]. The solids con en o SG is ypically
abou 75% and he pH is usually highe han 12.5 [
14
,
15
]. The boile ly ash (BFA) is gene a ed in a
biomass luidized bed boile , as a esul o he combus ion o wood ba k and o he wood esidues
o ene gy eco e y. The used pa icles a e ca ied upwa ds along wi h he lue gas. As he lue gas
app oaches he low- empe a u e zones, he used subs ances solidi y o o m ly ash, which is cap u ed
by cyclones, ab ic il e s and/o elec os a ic p ecipi a o s (ESP) wi h cleaning e iciency abo e 99% [
16
].
The ly ash consis s o ine pa icula es and p ecipi a ed ola iles, ypically wi h a high speci ic su ace
a ea [17]. The pH o BFA is ypically alkaline bu lowe han he obse ed o lime esidues [18].
Closing he loops in k a mills has en i onmen al ad an ages bu leads o he build-up in he
liquo cycle o non-p ocess elemen s (NPE), such as Ca, Mg, K, Mn, Ba, Fe, Al, Ni, Cu, Zn, e c., which
may hinde he pulping, bleaching o chemicals eco e y p ocess. NPE en e he pulping p ocess
h ough he main aw ma e ials, namely wood, make-up chemicals, wa e o may a ise om he
equipmen co osion [
19
]. In addi ion, he end o closing he wa e cycle accumula es NPE such
as Ca and K in he eco e y cycle. Thei accumula ion may lead o il a ion di icul ies, p ecipi a e
o ma ion, o e en in undesi able ca aly ic e ec s. The pu ge o NPE om he eco e y cycles is
essen ial o main ain no mal ope a ing condi ions. The was es unde analysis, speci ically GLD, SG,
and LM a e o g ea impo ance o he elimina ion o many NPE.
Appl. Sci. 2020,10, 2317 4 o 20
The speci ic p oduc ion o GLD, SG, LM and BFA in k a pulp mills is a iable depending on
he echnology and o he speci ic ac o s in each si e. E en hough, Table 1shows an o e iew o he
speci ic p oduc ion o each esidue.
Table 1. Speci ic was e gene a ion in k a pulp mills (kg/ AD).
Was es Indus ial In o ma ion (a) [3] [20] [21] [22] [23]
GLD 12 10–20 (b) 12 15 4–20 12.8
SG 10 7 16
LM 25 10–20 15 13
BFA 30 9(c) 20 5
(a) Da a p o ided by he Po uguese Indus y (The Na iga o Company); (b) includes g een liquo d egs (GLD) and
slake g i s (SG); (c) may be highe i biomass om ex e nal sou ces is also used; AD – ai d ied pulp.
Da a in Table 1demons a e ha he e a e a ia ions in he lows o each esidue, depending on
he echnology and he ope a ing condi ions a each si e. Howe e , conside ing he pulp p oduc ion
wo ldwide, hese was es ep esen a huge amoun . Fo example, acco ding o he li e a u e, in Finland
(one o he main Eu opean pulp p oduce s), abou 100 k o GLD we e p oduced pe yea [
22
], and he
wo ld p oduc ion can ise om 0.5 o 1.3 M [23].
3. Main P ope ies o he Ino ganic Was es
In his sec ion, he main physical and chemical p ope ies o GLD, SG, LM, and BFA a e highligh ed
o e eal he main p os and cons o a speci ic applica ion.
3.1. Chemical composi ion
Table 2shows he composi ion exp essed in oxides, de e mined by XRF, and also he loss on
igni ion (LOI).
Table 2.
Chemical composi ion o g een liquo d egs (GLD), slake g i s (SG), lime mud (LM), and
boile ly ash (BFA) de e mined by XRF (w %).
GLD SG LM BFA
[4] [24] [25] [5] [24] [26] [27] [28] [5] [23] [26] [29]
CaO 34.3 33.0 34.9 49.45 55.8 44.4–52.0 57.12 54.1 16.7 34.9 0.8–10.4 16.5
MgO 10.9 4.65 5.94 0.45 0.47 0.6–3.4 0.91 0.86 3.44 4.4 0.7–1.9 3.07
SiO20.23 2.35 ni 0.47 1.31 3.4–11.0 3.58 0.34 38.5 11.6 33.9–59.7 34.0
Al
2
O
31.94 0.69 0.47 0.29 0.42 0.5–1.4 0.07 0.07 14.8 4.4 16.5–35.4 13.5
Fe
2
O
30.61 0.65 0.59 0.05 <0.1 0.2–1.2 0.20 0.15 5.94 2.6 1.5–19.7 4.95
Na
2
O
2.10 11.7 9.49 4.52 0.60 ni 2.32 0.91 1.53 1.4 ni 1.52
K2O<0.1 1.03 0.37 0.27 <0.1 ni 0.26 0.06 5.97 6.5 ni 5.49
P2O5ni 0.33 0.37 0.38 0.65 ni 0.03 0.96 1.12 1.6 ni 1.11
TiO2ni <0.1 ni ni <0.1 ni ni ni 0.76 0.25 ni 0.65
MnO 4.21 0.37 0.06 ni <0.1 ni ni 0.09 0.50 1.4 ni 0.45
SO33.6 2.82 ni 1.86 0.11 ni 0.4 ni 2.66 11.4 ni 2.77
LOI ni 42.10 * ni 41.1 40.10 31.5–43.5 ni ni 6.38 15.8 1.2–33.6 14.3
LOI–Loss on igni ion; * De e mined a 1200 ◦C; ni–no indica ed.
These da a demons a e ha GLD, SG, and LM a e pa icula ly ich in Ca, while BFA con ains less
o his elemen . Indeed, BFA is ich in Si wi h no ewo hy con en in Al and Fe. In addi ion o Ca, GLD
also con ains no iceable Na and Mg con en . The concen a ion o K and P in BFA can be in e es ing
o he p oduc ion o e ilize s. The high LOI associa ed wi h hese was es is no mally due o he
deca bona ion o calci e ins ead o o ganic ma e , which gene ally is low [30].
Appl. Sci. 2020,10, 2317 5 o 20
3.2. Mine al phases
To selec he bes u iliza ion op ion in each case, i is meaning ul o iden i y he mine al phases
ha compose each ma e ial. Fo ha pu pose, XRD could be a aluable echnique, in pa icula , o
iden i y he c ys alline phases, as indica ed in Table 3. Acco dingly, i can be concluded ha calci e
(CaCO
3
) is p esen in all was es, whe eas in a much mo e exp essi e quan i y in GLD, SG, and LM.
Besides calci e, GLD also con ains dolomi e (CaMg(CO
3
)
2
), cesani e (Ca
2
Na
3
(SO
4
)
3
(OH)) and pi ssoni e
(Na
2
Ca(CO
3
)
2
.2H
2
O). Some e e ences indica e ha pi ssoni e is he dominan mine al [
21
,
29
] in GLD,
while o he s [
31
] indica e calci e as he mos ele an phase. Sodium migh be p esen in pi ssoni e,
cesani e, na i e (Na
2
CO
3
) as well as sodium sesquica bona e (Na
3
H(CO
3
)
2
). Sodium and sul u
con en esul om he g een liquo composi ion (mainly composed o Na
2
CO
3
and Na
2
S). In addi ion,
b uci e (Mg(OH)2) is commonly ound in GLD.
Rega ding SG, besides CaCO
3,
i may con ain dolomi e (CaMg(CO
3
)
2
), pi ssoni e
(Na
2
Ca(CO
3
)
2
.2H
2
O), po landi e (Ca(OH)
2
), la ni e (Ca
2
SiO
4
). The high concen a ion o
calcium-bea ing mine al phases in SG esul s om he slaking eac ion o quick lime wi h g een liquo
(aqueous solu ion o sodium hyd oxide, sodium sul ide, and sodium ca bona e) in he slake uni .
Mo eo e , qua z (SiO
2
), wus i e (FeO) and b uci e (Mg(OH)
2
) a e also de ec ed. Mg concen a ion in
he SG can be ela ed o he use o magnesium sul a e in he deligni ica ion p ocess in some mills [
19
].
As a o emen ioned, LM is o med in he caus icizing eac ion, and hus he main phase (mo e han
90%) is calci e [
30
], while some mino o ace phases may con ain Mg, Si, Al, Fe, Na, K, P, and S, bu
no mally no de ec ed h ough XRD. Besides calci e, which is clea ly iden i ied in X- ay di ac ion
spec a, in he li e a u e some mine als con aining Ca and Mg ca bona es ha e been iden i ied
(Ca(1−x)MgxCO3) [31].
Wi h espec o BFA, he majo mine als a e qua z (SiO
2
), calcium-bea ing mine als such as
calci e (CaCO
3
), dolomi e (CaMg(CO
3
)), anhyd i e (CaSO
4
) and po landi e (Ca(OH)
2
). Mo eo e ,
alumina (Al
2
O
3
), i on oxide (Fe
2
O
3
), pe iclase (MgO) and syl i e (KCl) also cons i u es he BFA in
a iable amoun s. In ac , BFA om coni e ous ees ends o con ain a highe amoun o Si and Ca
when compa ed o ha dwood ees and ela i ely low K and S con en [
32
]. The high calci e and
aluminosilica e con en s seem sui able as a cemen eplacemen ma e ial and as agg ega es o oad
cons uc ion [
32
]. A en ion should be paid o sul a e and chlo ide con en , which can be ha m ul in
conc e e applica ions. In pa icula , sul a e may lead o e ingi e sal s, which can cause c acks in he
inal ma e ial. Chlo ides can p o oke, o example, co osion in ein o ced conc e e. Rega ding he
nu ien s con en , BFA is poo in ni ogen due o i s ola iliza ion du ing combus ion and loss as gaseous
compounds. On he con a y, he amoun o K and P can be in e es ing o ag onomic applica ions.
Table 3. Mine al phases in GLD, SG, LM, and BFA iden i ied by XRD.
GLD SG LM BFA
Calci e (CaCO3) [4,24,31] Calci e (CaCO3) [5,24,31] Calci e (CaCO3) [31] Calci e (CaCO3) [5,23]
Dolomi e (CaMg(CO3)2) [23] Dolomi e (CaMg(CO3)2) [23] Ca(1−x)MgxCO3[31]
Dolomi e (CaMg(CO
3
)
2
) [
23
]
Cesani e (Ca2Na3(SO4)3(OH)) [23] Qua z (SiO2) [24] Hali e (NaCl) [23]
Na i e (Na2CO3) [23,24,33,34]
Pi ssoni e (Na
2
Ca(CO
3
)
2
.2H
2
O) [
31
]
Qua z (SiO2) [5,23,31]
Pi ssoni e (Na2Ca(CO3)2.2H2O) [4,21,30] Po landi e (Ca(OH)2) [31] Syl i e (KCl) [23]
Mangani e (Mn4O8H4) [4] Wus i e (FeO) [31] Anhyd i e (CaSO4) [23]
Sodium sesquica bona e (Na3H(CO3)2) [35] La ni e (Ca2SiO4) [31] Po landi e (Ca(OH)2) [23]
B uci e (Mg(OH)2) [35] B uci e (Mg(OH)2) [31] Pe iclase (MgO) [23]
3.3. Physico-chemical p ope ies
In o de o ind he bes applica ions o he was es conside ed, in addi ion o he elemen al
composi ion and mine als indica ed in Tables 2and 3, he knowledge o o he physical and chemical
p ope ies is undamen al, such as hose epo ed in Table 4.
The mois u e con en can a y in GLD, SG, and LM, depending on he echnology and ope a ing
condi ions in he pulp mill. High mois u e con en can be ad an ageous depending on he applica ion,
namely o dec ease he elease o dus in handling ope a ions. Howe e , anspo a ion cos s can be

Appl. Sci. 2020,10, 2317 6 o 20
highe , as well as he di icul ies in mixing wi h o he powde ed ma e ials ( o example, clay, and
cemen ). BFA is usually gene a ed wi h e y low mois u e, while showing high hyd ophilic p ope ies
and easily o ming agglome a es [32].
Table 4. O he ele an physicochemical p ope ies o selec echnological applica ions.
P ope y GLD SG LM BFA
Mois u e (%) 50.8 [36]; 48.0–57.0 [17],
54.0 [37]
15.7 [36]; 28.4 [19],
7.0–16.0 [17],
41.1 [38], 1.1–45.6
[17], 28.0 [39],
39–60 [26]
0.30–0.80 [40]
pH 12.8 [36]; 12.2 [25], 12.9 [4]13.1 [36]; 12.6 [25],
13.1 [19]12.6 [41] 11 [32]; 12.8 [42]; 13.3 [43]
EC (mS/cm) 26.2 [36]; 9.76 [4] 20,8 [36]; 94.3 [19] 7.3 [41] 13.6 [42]; 11.63 [43]
VS (% TS) 8.3 [36] 2.4 [19]
ANC (% CaCO3)64.4–95.6 [25], 8.3 mmol
H+/g [4]69.4–100 [25] 106 [41] 54.3–77.7 [25]
D50 (µm) 11.6 [24], 8.97 [4]; 6 [29] 24.1 [24] 49.3 [5]; 150–250 [32]
Densi y (g/cm3)2.498 [24], 2.47–2.60 [37] 2.703 [24] 2.83 [44], 2.43 [39] 2.4–2.8 [32], 2.615 [23]
Bulk densi y (g/cm3)1.2–1.64 [4], 0.44–0.67 [37] 0.15–1.3 [32]
Sa (m2/g) 72.08 [24]; 12–21 [37] 2.901 [24] 5.17 [44]3.03 [5]; 4.2–101 [32],
3.25 [23]
HC (m/s) 8.8 ×10−9−1×10−8[4]
Kjeldahl N (%) 0.07 [25] 0.05 [25] 0.17 [25]
Chlo ides (%) 0.30 [29]; 0.8 [36]0.1 [12]; 0.02 [19];
0.1 [36]
0.08 [44]; <LQ [45];
0.06 [46]
1.5 [29]; 2.7 [23]; 1.2 [45];
1.2 [43]; 0.10 [46]
EC–elec ical conduc i i y; VS– ola ile solids; ANC–acid neu aliza ion capaci y; D
50
–median size; S
a
–speci ic a ea;
HC–hyd aulic conduc i i y.
A key p ope y o de ine he bes applica ion o a speci ic ma e ial is he pH. In his case, he ou
was es a e alkaline, and e y high alues (>13) can be obse ed in ce ain cases (e.g., o SG). Thus, i no
p ope ly managed, hey can cause co osion and eco oxici y p oblems in na u al ecosys ems. Howe e ,
his p ope y may also be posi i e in ce ain applica ions, o example, o be used as neu alizing
agen s, liming applica ions o as ope a ing supply in applica ions ha no mally use alkaline aw
ma e ials (e.g., cemen ). BFA e eals an a e age pH o 11, bu can a y be ween 8 and 13 [32].
F om he elec ical conduc i i y (EC) i is possible o in e he o al concen a ion o dissol ed
elec oly es (o o al dissol ed solids, TDS) in aqueous suspension. In his con ex , i is impo an
o no e ha some applica ions do no allow high ionic s eng h (applica ions as liming agen ), bu
i he was e is used in bound ma e ials (e.g., in cemen o mula ions) his would no be a p oblem.
Wa kins e al. [19]
measu ed a concen a ion o TDS equal o 88.5 g/kg in SG leacha es, which exceed
bo h he EU limi s o ine was e land ill (4 g/kg) and he non-haza dous was e land ill (60 g/kg dw).
The o ganic ma e o ola ile solids (VS de e mined a 550
◦
C o 2–4 h un il cons an weigh ) is
in gene al low (much less han 8%) in all hese was es, which a e hen classi ied as ino ganic.
The acid neu aliza ion capaci y (ANC) o alkalini y o bu e ing capaci y o GLD, SG, and LM is
ypically high. This p ope y can be measu ed as calcium ca bona e equi alen s and as can be seen in
Table 4, alues close o 100% can be ob ained o GLD, SG, and LM, while lowe alues a e common
o BFA [
25
]. Mäki alo e al. [
37
] epo ed ha o keep pH >6, he a e age ANC was 18.5 mmol H+/g
o GLD. This p ope y is pa icula ly impo an o assessing he po en ial applica ions as a liming
agen o soil o as neu aliza ion ma e ial o acid was ewa e s o in alkaline ba ie s.
All o hose ma e ials a e gene a ed in g anula o m. BFA shows, in gene al, a coa se pa icle
size dis ibu ion, while GLD is a e y ine powde wi h a mean pa icle size o a ew mic ome e s [
29
].
Some o hem a e gene a ed in agglome a es (SG and LM) bu could be easily disin eg a ed i equi ed.
Thus, he bulk densi y is lowe o close o 1 g/cm
3
, whe eas he eal (o skele al) densi y may each
alues highe han 2.4 g/cm
3
o all o hose was es. Indeed, o ins ance o GLD, al hough he bulk
densi y anges be ween 0.44 and 0.67 g/cm
3
, he eal densi y may achie e om 2.47 o 2.60 g/cm
3
[
37
].
The speci ic su ace a ea, S
a
, may a y wi hin each was e, bu expec ed alues a e om a ew m
2
/g
o abou 100 m
2
/g. Fo using hese ma e ials in geo echnical applica ions such as sealing laye o
wa e and oxygen, he hyd aulic conduc i i y is a ele an p ope y. This pa ame e has no been
Appl. Sci. 2020,10, 2317 7 o 20
epo ed much in he li e a u e. Ne e heless, he hyd aulic conduc i i y measu ed o GLD a y om
3.7 ×10−9–4.6 ×10−8m/s, which is a low alue and simila o hose o sil o muddy mo aine [4].
I is impo an o no e ha hese was es a e de ini ely no ni ogen sou ces (Kjeldahl N less han
0.05%). The con en o chlo ides could limi speci ic applica ions, namely o clinke p oduc ion o in
conc e e and mo a applica ions. Da a om he li e a u e shows ha he con en o chlo ides in GLD,
SG, and LM is no mally low, whils BFA can con ain a sligh ly highe amoun .
3.4. Po en ially oxic me als
To ind eliable applica ions while p o ec ing he en i onmen , he o al con en o po en ially
oxic me als (PTM) and hei leaching beha io a e o high impo ance. Table 5summa izes he o al
quan i ies o di e se PTM commonly ound in he ou ino ganic was es. Fo compa ison pu poses,
h ee addi ional e e ences a e also included. In pa icula , he Finnish limi s o he use o ash as a
o es e ilize , he Finnish limi s in espec o he maximum allowable elemen concen a ions in ashes
(e.g., om coal, pea , and biomass) used as ea h cons uc ion ma e ial [
19
] and he a e age c us al
abundance o hese elemen s.
Table 5. The o al con en o po en ially oxic elemen s (mg/kg).
GLD SG LM BFA Limi FF Limi CM C us *
[4] [25] [30] [19] [25] [28] [41] [25] [42] [47] [47] [19] [48]
Pb 6.12 46.8 13 <3 34.1 6.79 <3 44.3 28.7 31 150 300 12.5
Cd 3.81 5.19 9.4 0.3 4.75 0.91 <0.3 4.7 2.9 3.3 25 15 0.2
Cu 229 80.9 102 <10 4.6 0.73 4.1 25.8 63.6 72 700 400 55
C 295 56.0 118 12.6 12.4 16.7 7.0 24.1 66.9 74 300 400 100
Ni 233 189 84 23.9 25.2 ni 4.0 97.4 32.4 33 150 ni 75
Zn 3197 160 1000 9.9 15.0 ni 36 68.9
295.3
320 4500 2000 70
Hg
<0.05
ni ni
<0.03
ni
<0.04 <0.03
ni 0.03 0.1 1.0 ni ni
Vni ni 1.9 39.0 ni ni ni ni 92.7 ni ni 400 135
Mo 0.29 ni 1.7 <1 ni ni 2 ni 3.8 ni ni 50 1.5
As <0.1 ni 0.3 <3 ni 0.38 2.7 ni 13.0 14 40 50 1.8
ni–no indica ed; Limi FF–cu en Finnish limi alues o ash used as a o es e ilize ; Limi CM–limi s in Finnish
legisla ion o ashes use as an ea h cons uc ion ma e ial; * A e age c us al abundance
Table 5 e eals low concen a ions o PTM in GLD, SG, LM, and BFA. The legal Limi FF is
ul illed o all elemen s, excep o Ni in he GLD, whe eas he Limi CM is exceeded only once o
Zn (concen a ions ma ked in bold in Table 5). The concen a ions o PTM can also be compa ed o
a e age c us al abundances and i is possible o conclude ha some o he elemen s can be signi ican ly
en iched in hese an h opogenic ma e ials. Indeed, he concen a ions o Pb, Cd, Cu, C , Ni, and Zn
may be en iched in all was es. Howe e , i is possible o suppo he bene icial use o ino ganic was es
ins ead o land illing [
19
]. The discussion p esen ed in he nex sec ion will demons a e ha among
he possibili ies o u iliza ion, some o hem encapsula e he was e in a ma ix, and hus educe he
leaching p ocesses. Indeed, om an en i onmen al poin o iew, he leaching beha io o each PTM is
mo e impo an han he o al elemen al con en . I is well known ha he leaching beha io o each
elemen may p esen a speci ic pa e n: ampho e ic leaching (high leaching in acidic and basic pH
condi ions, wi h a U shape), ca ionic leaching (wi h high leaching in acidic pH), and a leaching pa e n
no dependen on he elua e pH. Mo eo e , he leaching can be con olled by solubili y es ic ions
o a ailabili y. Thus, o each applica ion, he leaching beha io mus be conside ed o assess he
en i onmen al impac . In he li e a u e, di e se s udies add essed he leaching o hese was es. Jia e
al. [
4
] analyzed he leaching o GLD ega ding Ca, Fe, K, Mg, Na, Si, Al, As, Cd, Co, C , Cu, Hg, Mn,
Mo, Ni, Pb, Sn, and SO
42−
[
4
]. The leaching solu ions o GLD e ealed low Eh, high pH and EC, and
hus low mobili y o me als. The legal limi s o ine land ills we e exceeded only in a ew samples o
As, C , and Zn. Wa kins e al. [
19
] highligh ed ha he e y low me al concen a ions in SG suppo s
u iliza ion ins ead o disposal in land ill, indica ing ha he concen a ions o As, Ba, Cd, C , Cu, Mo,
Pb, V, and Zn a e clea ly lowe han he allowable concen a ions in o he ma e ials used as an ea h
Appl. Sci. 2020,10, 2317 8 o 20
cons uc ion agen . In addi ion, he leached concen a ions o hea y me als, chlo ide, luo ide om SG
we e lowe han he EU limi s o disposed was e in ine was e land ills. Ne e heless, sul a e can
exceed he limi o ine was e land ills (1000 mg/kg dw), since he alue ound was 5250 mg/kg.
Addi ionally, Che ian and Siddiqua [
32
] concluded ha ly ash om pulp and pape mills is
in gene al conside ed non-haza dous, since PTM a e mainly held in he amo phous aluminosilica e
phases, and hus wi h low solubili y. Ribei o e al. [
49
] p oduced a glass om BFA and he ma e ial
exhibi ed a sa is ac o y leaching beha io . Mo eo e , Al a enga e al. [
43
] highligh ed ha biomass
ashes p oduced in Po ugal con ain e y low me als concen a ion. Cab al e al. [
25
] es ed GLD, SG,
and LM as al e na i e liming ma e ials and concluded ha me als do no appea o be a limi ing ac o
o hei use in he soil.
4. Po en ial Applica ions
Al hough k a pulp mills ha e de eloped sophis ica ed in eg a ed was e managemen plans, wi h
he objec i e o minimizing he gene a ion o was e and land illed quan i ies, possibili ies o euse,
ecycling o eco e y a e s ill lacking. The main objec i e o was e managemen in he pulp indus y
includes i s use on-si e o in o he indus ies ollowing an indus ial ecology app oach. Figu e 2
p o ides an o e iew o he po en ial ca ego ies o applica ions ound in he li e a u e o GLD, SG,
LM, and BFA.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 9 o 21
Figu e 2. Ca ego ies o he po en ial applica ions o ino ganic was es om he pulp indus y.
4.1. G een Liquo D egs
Chemical cha ac e is ics o GLD such as he s ongly alkaline pH (>10), he p esence o alkaline
and alkaline-ea h oxides, and he lack o knowledge o i s long- e m chemical s abili y, echnical
pe o mance and en i onmen al impac o se e al applica ions can hinde i s po en ial inco po a ion
in ma e ials. This may explain why his indus ial by-p oduc emains unexplo ed on an indus ial
scale. Despi e ha , se e al s udies ha e a emp ed o sea ch o al e na i e managemen ou es, as
lis ed in Table 6. Reducing disposal in land ills can esul no only in signi ican en i onmen al and
economic bene i s, bu also in educing he need o na u al aw ma e ials.
Table 6. Applica ions o GLD epo ed in he li e a u e.
Applica ion Highligh s Scale
Cons uc ion ma e ials
Conc e e GLD as a eplacemen o pa o he cemen in conc e e is no sui able since
he loss in mechanical p ope ies is signi ican [23].
Labo a o y
Cemen Subs i u ion o clinke up o 10% is easible o ob ain Po land cemen (CP
I-S and CP II-F) [50].
Labo a o y
Clinke
p oduc ion
The mix u e o GLD (0.13 w %) wi h s anda d ma e ials is echnically
iable and does no p esen no iceable en i onmen al e ec s [34].
Indus ial
Geopolyme
mo a s
GLD can be used as a ine ille up o 25 w % inco po a ion. The ob ained
mo a s exhibi ed enhanced ensile and comp essi e s eng h [29].
Labo a o y
Geo echnical
Land ill co e Al e na ing laye s o 0.15 m o GLD (70 w %) and SG (30 w %) co e ed by
1 m o MSW ha e he po en ial o eplacing soil as in e media e co e ing
in land ills [27].
Indus ial
Figu e 2. Ca ego ies o he po en ial applica ions o ino ganic was es om he pulp indus y.
4.1. G een Liquo D egs
Chemical cha ac e is ics o GLD such as he s ongly alkaline pH (>10), he p esence o alkaline
and alkaline-ea h oxides, and he lack o knowledge o i s long- e m chemical s abili y, echnical
pe o mance and en i onmen al impac o se e al applica ions can hinde i s po en ial inco po a ion
in ma e ials. This may explain why his indus ial by-p oduc emains unexplo ed on an indus ial
scale. Despi e ha , se e al s udies ha e a emp ed o sea ch o al e na i e managemen ou es, as
Appl. Sci. 2020,10, 2317 9 o 20
lis ed in Table 6. Reducing disposal in land ills can esul no only in signi ican en i onmen al and
economic bene i s, bu also in educing he need o na u al aw ma e ials.
Table 6. Applica ions o GLD epo ed in he li e a u e.
Applica ion Highligh s Scale
Cons uc ion ma e ials
Conc e e GLD as a eplacemen o pa o he cemen in conc e e is no
sui able since he loss in mechanical p ope ies is signi ican [23].
Labo a o y
Cemen Subs i u ion o clinke up o 10% is easible o ob ain Po land
cemen (CP I-S and CP II-F) [50].
Labo a o y
Clinke p oduc ion The mix u e o GLD (0.13 w %) wi h s anda d ma e ials is
echnically iable and does no p esen no iceable en i onmen al
e ec s [34].
Indus ial
Geopolyme mo a s GLD can be used as a ine ille up o 25 w % inco po a ion. The
ob ained mo a s exhibi ed enhanced ensile and comp essi e
s eng h [29].
Labo a o y
Geo echnical
Land ill co e Al e na ing laye s o 0.15 m o GLD (70 w %) and SG (30 w %)
co e ed by 1 m o MSW ha e he po en ial o eplacing soil as
in e media e co e ing in land ills [27].
Indus ial
Road pa emen
cons uc ion
GLD equi e washing be o e inco po a ion as agg ega es in
bi uminous mix u es o gua an ee s abili y in e ms o wa e
sensi i i y [36].
Labo a o y
Sealing laye in mines A mix u e wi h he p opo ions 7:2:1 o ailings: GLD: ly ash was
ound o be geo echnically sa is ac o y o be used as a sealing laye
in d y co e s on mine [37]. GLD showed high wa e e en ion
capaci y and low hyd aulic conduc i i y, which p e en s wa e
pe cola ion and oxygen anspo [51].
Labo a o y
Ho -mix asphal
GLD used as ille in ho -mix asphal leads o poo wa e esis ance,
despi e displaying adequa e mechanical p ope ies (s i ness and
pe manen de o ma ion) [52].
Labo a o y
En i onmen al
Neu alize acidic
was ewa e s
The liming e ec o GLD (39.6% Ca eq) is simila o comme cial
limes one (38%). The pH o 10.7 indica es a s ong liming
e ec [53,54].
Indus ial
Acid mine d ainage
emedia ion
GLD exhibi ed high bu e ing capaci y [4] a low dosages o
1 g/L [55] o emedia ion o acid mine d ainage.
Labo a o y
Soil amendmen Doses up o 20 /ha achie ed neu aliza ion o acidic soil, no
causing de e io a ion o soil p ope ies o dep essing c op
yields [56]. A e 5.5 yea s since applica ion, posi i e e ec s we e
obse ed on he soil chemical a ibu es [57].
Labo a o y
D ying adju an o
sewage sludge
A dose o 0.15 g GLD pe g o sewage sludge educed by 8% he
ene gy equi ed o he e apo a ion o humidi y a 130 ◦C. A
educ ion in phy o oxici y was also obse ed in es s wi h ga den
c ess, e ealing a good po en ial o ag icul u al applica ions [34].
Labo a o y
Ag icul u al
Liming ma e ial
Valid op ion o subs i u e comme cial ag icul u al limes one [
25
,
41
].
Indus ial
Co-compos ing The addi ion o a mode a e amoun o GLD (5–8 w %) wi h k a
mill sludge did no show a nega i e e ec on he biological ac i i ies
du ing he compos ing p ocess [58].
Labo a o y
Despi e he in e es in de eloping applica ions o GLD, some s udies ha e e ealed i s p ope ies
inadequa e o he in ended pu pose. Fo example, he inco po a ion o GLD as cemen eplacemen
in conc e e yielded p oduc s wi h inapp op ia e quali y [
23
]. GLD also disclosed inadequa e wa e
esis ance o ho -mix asphal o oad pa emen in geo echnical applica ions [
52
]. Howe e , a ew
Appl. Sci. 2020,10, 2317 16 o 20
Lis o Ac onyms
AMD Acid mine d ainage
ANC Acid neu aliza ion capaci y
BFA Boile ly ash
CEM Types o Cemen
CEPI Con ede a ion o Eu opean Pape Indus ies
CM Limi s in Finnish legisla ion o ashes use
CNP Calcium hyd oxide nanopa icles
COD Chemical oxygen demand
dw D y weigh
EC Elec ical conduc i i y
Eh Redox po en ial
EoW End-o -was e c i e ia
FF Finnish legal limi
HC Hyd aulic conduc i i y
GLD G een liquo d egs
LCA Li e cycle assessmen
LM Lime mud
LOI Loss on igni ion
MSW Municipal Solid Was es
NPE Non-p ocess elemen s
PTM Po en ially oxic me als
Sa Speci ic a ea
SG Slake g i s
TDS To al dissol ed solids
UCS Uncon ined comp essi e s eng h
VS Vola ile solids
XRD X- ay di ac ion
XRF X- ay luo escence
WoS Web o Science
Re e ences
1. CEPI Key S a is ics. Eu opean Pulp & Pape Indus y; CEPI: London, UK, 2018.
2.
Eu opean Commission. COM Communica ion om he Commission o he Eu opean Pa liamen , he Council, he
Eu opean Economic and Social Commi ee and he Commi ee o he Regions, Closing he Loop—An EU Ac ion Plan
o he Ci cula Economy; Eu opean Commission: Maas ich , The Ne he lands, 2015.
3.
Eu opean Commission. BREF Bes A ailable Techniques (BAT) Re e ence Documen o he P oduc ion o Pulp,
Pape and Boa d; Eu opean Commission: Maas ich , The Ne he lands, 2015.
4.
Jia, Y.; Hambe g, R.; Qu eshi, A.; Mäki alo, M.; Mau ice, C. Va ia ion o g een liquo d egs om di e en
pulp and pape mills o use in mine was e emedia ion. En i on. Sci. Pollu . Res.
2019
,26, 31284–31300.
[C ossRe ] [PubMed]
5.
Saeli, M.; Sen , L.; Tobaldi, D.M.; La Scalia, G.; Seab a, M.P.; Lab incha, J.A. Inno a i e ecycling o lime slake
g i s om pape -pulp indus y eused as agg ega e in ambien cu ed biomass ly ash-based geopolyme s o
sus ainable cons uc ion ma e ial. Sus ainabili y 2019,11, 3481. [C ossRe ]
6.
Bajpai, P. En i onmen ally Benign App oaches o Pulp Bleaching, 2nd ed.; Else ie : Ams e dam,
The Ne he lands, 2012.
7. Bie mann, C.J. Handbook o Pulping and Pape making, 2nd ed.; Else ie : Ams e dam, The Ne he lands, 1996.
8.
Sjös öm, E. Wood chemis y: Fundamen als and Applica ions, 2nd ed.; Academic P ess: San Diego, CA,
USA, 1993.
9. Walke , J. P ima y Wood P ocessing: P inciples and P ac ice; Sp inge : Be lin/Heidelbe g, Ge many, 2006.
10. Bajpai, P. Bio echnology o Pulp and Pape P ocessing, 2nd ed.; Sp inge : Singapo e, 2018.
11.
Golmaei, M.; Kinna inen, T.; Je ns öm, E.; Häkkinen, A. Ex ac ion o haza dous me als om g een liquo
d egs by e hylenediamine e aace ic acid. J. En i on. Manage. 2018,212, 219–227. [C ossRe ] [PubMed]

Appl. Sci. 2020,10, 2317 17 o 20
12.
Tikka, P. Pape making Science and Technology, Book 6 (Pa 2), 2nd ed.; Pape Enginee s’ Associa ion/Pape i ja
Puu Oy: Helsinki, Finland, 2008.
13.
He, J.; Lange, C.R.; Doughe y, M. Labo a o y s udy using pape mill lime mud o ag onomic bene i . P ocess
Sa . En i on. P o . 2009,87, 401–405. [C ossRe ]
14.
Sanchez, D.; T an, H. T ea men o Lime Slake G i and G een Liquo D egs-Cu en P ac ice. In P oceedings
o he TAPPI Enginee ing, Pulping & En i onmen al Con e ence, Philadelphia, Pennsyl ania, 25–31 Augus
2005; pp. 1–9.
15.
Poykio, R.; Nu mesniemi, H.; Dahl, O.; Wa kins, G.; Manskinen, K. E alua ion o he bio-accessible
non-p ocess elemen concen a ions in slake g i s by syn he ic swea and gas ic luids ex ac ion. J. En i on.
Occup. Sci. 2014,3, 65–70. [C ossRe ]
16.
Mikkanen, P. Fly Ash Pa icle Fo ma ion in K a Reco e y Boile s; Helsinki Uni e si y o Technology: Espoo,
Finland, 2000.
17.
Sim
ã
o, L.; Ho za, D.; Raupp-Pe ei a, F.; Lab incha, J.A.; Mon edo, O.R.K. Was es om pulp and pape
mills—A e iew o gene a ion and ecycling al e na i es. Ce amica 2018,64, 371. [C ossRe ]
18.
S hiannopkao, S.; S eesai, S. U iliza ion o pulp and pape indus ial was es o emo e hea y me als om
me al inishing was ewa e . J. En i on. Manage. 2009,90, 3283–3289. [C ossRe ]
19.
Wa kins, G.; Pöykiö, R.; Nu mesniemi, H.; Dahl, O. Ea h cons uc ion and land ill disposal op ions o slake
g i s. Res. J. Appl. Sci. Eng. Technol. 2010,2, 757–764.
20.
Modolo, R.C.E. Valo iza ion o Solid Was es om Cellulose and Pape Indus y. PhD Thesis, Uni e si y o
A ei o, A ei o, Po ugal, 2014.
21.
Manskinen, K.; Nu mesniemi, H.; Pöykiö, R. To al and ex ac able non-p ocess elemen s in g een liquo
d egs om he chemical eco e y ci cui o a semi-chemical pulp mill. Chem. Eng. J.
2011
,166, 954–961.
[C ossRe ]
22.
Nu mesniemi, H.; Pöykiö, R.; Pe ämäki, P.; Kuokkanen, T. The use o a sequen ial leaching p ocedu e o
hea y me al ac iona ion in g een liquo d egs om a caus icizing p ocess a a pulp mill. Chemosphe e
2005
,
61, 1475–1484. [C ossRe ]
23.
Ma
í
nez-Lage, I.; Velay-Lizancos, M.; V
á
zquez-Bu go, P.; Ri as-Fe n
á
ndez, M.; V
á
zquez-He e o, C.;
Ram
í
ez-Rod
í
guez, A.; Ma
í
n-Cano, M. Conc e es and mo a s wi h was e pape indus y: Biomass ash
and d egs. J. En i on. Manage. 2016,181, 863–873. [C ossRe ] [PubMed]
24.
San os, V.R.; Dezena Cab elon, M.; de Sousa T ich
ê
s, E.; Quin ei o, E. G een liquo d egs and slake g i s
esidues cha ac e iza ion o a pulp and pape mill o u u e applica ion on ce amic p oduc s. J. Clean. P od.
2019,240, 118220. [C ossRe ]
25.
Cab al, F.; Ribei o, H.M.; Hil
á
io, L.; Machado, L.; Vasconcelos, E. Use o pulp mill ino ganic was es as
al e na i e liming ma e ials. Bio esou . Technol. 2008,99, 8294–8298. [C ossRe ] [PubMed]
26.
Qin, J.; Cui, C.; Cui, X.; Hussain, A.; Yang, C.; Yang, S. Recycling o lime mud and ly ash o ab ica ion o
ano hi e ce amic a low sin e ing empe a u e. Ce am. In . 2015,41, 5648–5655. [C ossRe ]
27.
Fa age, R.M.P.; Sil a, C.M.; Passos Rezende, A.A.; Lelis Leal de Souza, J.J.; Teixei a de Ma os, A.; Vinha
Zanuncio, A.J. In e media e co e ing o municipal solid was e land ills wi h alkaline g i s, d egs and lime
mud by-p oduc s o k a pulp p oduc ion. J. Clean. P od. 2019,239, 117985. [C ossRe ]
28.
Mahmoudkhani, M.; Richa ds, T.; Theliande , H. Recycling o solid esidues o he o es : Expe imen al and
heo e ical s udy o he elease o sodium om lime mud and g een liquo d egs agg ega es. P ocess Sa .
En i on. P o . 2004,82, 230–237. [C ossRe ]
29.
No ais, R.M.; Ca alhei as, J.; Sen , L.; Lab incha, J.A. Upcycling unexplo ed d egs and biomass ly ash
om he pape and pulp indus y in he p oduc ion o eco- iendly geopolyme mo a s: A p elimina y
assessmen . Cons . Build. Ma e . 2018,184, 464–472. [C ossRe ]
30. Kinna inen, T.; Golmaei, M.; Je ns öm, E.; Häkkinen, A. Sepa a ion, ea men and u iliza ion o ino ganic
esidues o chemical pulp mills. J. Clean. P od. 2016,133, 953–964. [C ossRe ]
31.
Ma ins, F.M.; Ma ins, J.M.; Fe acin, L.C.; da Cunha, C.J. Mine al phases o g een liquo d egs, slake g i s,
lime mud and wood ash o a K a pulp and pape mill. J. Haza d. Ma e . 2007,147, 610–617. [C ossRe ]
32. Che ian, C.; Siddiqua, S. Pulp and Pape Mill Fly Ash: A Re iew. Sus ainabili y 2019,11, 4394. [C ossRe ]
33.
Siquei a, F.B.; Holanda, J.N.F. Reuse o g i s was e o he p oduc ion o soil-cemen b icks. J. En i on.
Manage. 2013,131, 1–6. [C ossRe ] [PubMed]
Appl. Sci. 2020,10, 2317 18 o 20
34.
Cas o, F.; Vila inho, C.; T ancoso, D.; Fe ei a, P.; Nunes, F.; Mi agaia, A. U ilisa ion o pulp and pape
indus y was es as aw ma e ials in cemen clinke p oduc ion. In . J. Ma e . Eng. Inno .
2009
,1, 74–90.
[C ossRe ]
35.
Gomes, L.A.; San os, A.F.; G
ó
is, J.C.; Quina, M.J. The mal dehyd a ion o u ban biosolids wi h g een liquo
d egs om pulp and pape mill, Jou nal o En i onmen al Managemen . J. En i on. Manage.
2020
,261,
109944. [C ossRe ]
36.
Modolo, R.; Ben a, A.; Fe ei a, V.M.; Machado, L.M. Pulp and pape plan was es alo isa ion in bi uminous
mixes. Was e Manag. 2010,30, 685–696. [C ossRe ] [PubMed]
37.
Mäki alo, M.; Mau ice, C.; Jia, Y.; Öhlande , B. Cha ac e iza ion o g een liquo d egs, po en ially use ul o
p e en ion o he o ma ion o acid ock d ainage. Mine als 2014,4, 330–344. [C ossRe ]
38.
Roye -Ta di , S.; Whalen, J.; Ri es , D. Can alkaline esiduals om he pulp and pape indus y neu alize
acidi y in o es soils wi hou inc easing g eenhouse gas emissions? Sci. To al En i on.
2019
,663, 537–547.
[C ossRe ] [PubMed]
39.
E o
ˇ
glu, H.; Aca , H.H.; Üçüncü, O.; Imamo
ˇ
glu, S. Soil s abiliza ion o o es oads sub-base using lime mud
was e om he chemical eco e y p ocess in alkaline pulp mill. J. Appl. Sci. 2006,6, 1199–1203.
40. E iegni, L.; Campbell, A.G.; Mahle , R.L. E alua ion o wood ash disposal on ag icul u al land. i. po en ial
as a soil addi i e and liming agen . Commun. Soil Sci. Plan Anal. 1991,22, 243–256. [C ossRe ]
41.
Pöykiö, R.; Nu mesniemi, H. Calcium ca bona e was e om an in eg a ed pulp and pape mill as a po en ial
liming agen . En i on. Chem. Le . 2008,6, 47–51. [C ossRe ]
42.
Pöykiö, R.; Mäkelä, M.; Wa kins, G.; Nu mesniemi, H.; Dahl, O. Hea y me als leaching in bo om ash and ly
ash ac ions om indus ial-scale BFB-boile o en i onmen al isks assessmen . T ans. Non e ous Me . Soc.
China 2016,26, 256–264. [C ossRe ]
43.
Al a enga, P.; Rod igues, D.; Mou inha, C.; Palma, P.; de Va ennes, A.; C uz, N.; Ta elho, L.A.C.; Rod igues, S.
Use o was es om he pulp and pape indus y o he emedia ion o soils deg aded by mining ac i i ies:
Chemical, biochemical and eco oxicological e ec s. Sci. To al En i on.
2019
,686, 1152–1163. [C ossRe ]
[PubMed]
44.
Modolo, R.C.E.; Sen , L.; Lab incha, J.A.; Fe ei a, V.M.; Ta elho, L.A.C. Lime mud om cellulose indus y
as aw ma e ial in cemen mo a s. Ma e . Cons . 2014,64, 316. [C ossRe ]
45.
Bu ube i, L.H.; Seab a, M.P.; Lab incha, J.A. P epa a ion o clinke om pape pulp indus y was es.
J. Haza d. Ma e . 2015,286, 252–260. [C ossRe ] [PubMed]
46.
Sim
ã
o, L.; Jius i, J.; L
ó
h, N.J.; Ho za, D.; Raupp-Pe ei a, F.; Lab incha, J.A.; Mon edo, O.R.K. Was e-con aining
clinke s: Valo iza ion o al e na i e mine al sou ces om pulp and pape mills. P ocess Sa . En i on. P o .
2017,109, 106–116. [C ossRe ]
47.
Nu mesniemi, H.; Mäkelä, M.; Pöykiö, R.; Manskinen, K.; Dahl, O. Compa ison o he o es e ilize
p ope ies o ash ac ions om wo powe plan s o pulp and pape mills incine a ing biomass-based uels.
Fuel P ocess. Technol. 2012,104, 1–6. [C ossRe ]
48.
Taylo , S.R. Abundance o chemical elemen s in he con inen al c us : A new able. Geochim. Cosmochim.
Ac a 1964,28, 1273–1285. [C ossRe ]
49.
Ribei o, A.S.M.; Mon ei o, R.C.C.; Da im, E.J.R.; Fe nandes, M.H.V. Ash om a pulp mill
boile -Cha ac e isa ion and i i ica ion. J. Haza d. Ma e . 2010,179, 303–308. [C ossRe ]
50.
To es, C.M.; Sil a, C.M.; Ped o i, L.G.; Fe nandes, W.; Ballo in, F.C.; Zanuncio, J.C. Cemen Po land
p oduc ion wi h d egs and g i s om k a pulp mills inco po a ed o clinke . In P oceedings o he 6 h
In e na ional Wo kshop Ad ances in Cleane P oduc ion, São Paulo, B azil, 24–26 May 2017; pp. 1–12.
51.
Mäki alo, M. G een Liquo D egs as Sealing Laye Ma e ial o Co e Sulphidic Mine Was e Deposi s. PhD
Thesis, Luleå ekniska uni e si e , Luleå, Sweden, 2012.
52.
Pasand
í
n, A.R.; P
é
ez, I.; Ram
í
ez, A.; Cano, M.M. Mois u e damage esis ance o ho -mix asphal made wi h
pape indus y was es as ille . J. Clean. P od. 2016,112, 853–862. [C ossRe ]
53.
Nu mesniemi, H.; Pöykiö, R.; Keiski, R.L. A case s udy o was e managemen a he No he n Finnish pulp
and pape mill complex o S o a Enso Vei siluo o Mills. Was e Manag. 2007,27, 1939–1948. [C ossRe ]
54.
Pöykö, R.; Nu mesniemi, H.; Kuokkanen, T.; Pe ämäki, P. G een liquo d egs as an al e na i e neu alizing
agen a a pulp mill. En i on. Chem. Le . 2006,4, 37–40. [C ossRe ]
Appl. Sci. 2020,10, 2317 19 o 20
55.
Sebogodi, K.R.; Johakimu, J.K.; Si hole, B.B. Bene icia ion o pulp mill was e g een liquo d egs: Applica ions
in ea men o acid mine d ainage as new disposal solu ion in Sou h A ica. J. Clean. P od.
2019
,246, 118979.
[C ossRe ]
56.
˙
Zołnowski, A.C.; S ˛adej, W.; Suski, M.S.; Wy was, A.; Sk ocki, D. Impac o Pape Mill Was e on
Physicochemical P ope ies o Soil, C op Yield, and Chemical Composi ion o Plan s. CLEAN Soil Ai
Wa e 2019,47, 1900080. [C ossRe ]
57.
P
é
ile, P.; Albuque que, J.A.; Ga iboni, L.C.; da Cos a, A.; Luciano, R.V. Co ec i e Po en ial o Alkaline
Residue (D egs) om Cellulose Indus y in an Acid Soil Cul i a ed Unde No- illage. Commun. Soil Sci.
Plan Anal. 2017,48, 1868–1880. [C ossRe ]
58.
Zamb ano, M.; Pich
ú
n, C.; Al ea , M.; Villa oel, M.; Vel
á
squez, I.; Baeza, J.; Vidal, G. G een liquo d egs
e ec on K a mill seconda y sludge compos ing. Bio esou . Technol. 2010,101, 1028–1035. [C ossRe ]
59.
Pape Chain Ci cula Case 1. A ailable online: h ps://www.pape chain.eu/ci cula -cases/ci cula -case-1/
(accessed on 24 Janua y 2020).
60.
Siquei a, F.B.; Holanda, J.N.F. Applica ion o g i s was e as a enewable ca bona e ma e ial in manu ac u ing
wall iles. Ce am. In . 2018,44, 19576–19582. [C ossRe ]
61.
Pai a, H.; Sim
õ
es, F.; Mo ais, M.; Fe ei a, V.M. Pilo es in ol ing pulp and pape indus y was es in oad
pa emen s. In Was es: Solu ions, T ea men s and Oppo uni ies III; Vila inho, C., Cas o, F., Gonçal es, M.,
Fe nando, A.L., Eds.; CRC P ess: Boca Ra on, FL, USA, 2019; pp. 20–26.
62.
P
é
ez-L
ó
pez, R.; Quispe, D.; Cas illo, J.; Nie o, J.M. Acid neu aliza ion by dissolu ion o alkaline pape mill
was es and implica ions o ea men o sul ide-mine d ainage. Am. Mine al.
2011
,96, 781–791. [C ossRe ]
63.
Fa age, R.; Quina, M.J.; Gando-Fe ei a, L.; Sil a, C.M.; Souza, J.L.; To es, C.M. K a pulp mill d egs and
g i s as pe meable eac i e ba ie o emo al o coppe and sul a e in acid mine d ainage. Sci. Rep.
2020
,
10, 4083. [C ossRe ]
64.
Nu mesniemi, H.; Dahl, O.; Wa kins, G.; Pöykiö, R. Slake g i s om he caus icising p ocess o a pulp
mill—A po en ial e ilise and liming agen ma e ial o use in ag icul u e and o es y. In . J. Ma e . Eng.
Inno . 2010,1, 312–324. [C ossRe ]
65.
Nu mesniemi, H.; Pöykiö, R.; Wa kins, G.; Dahl, O. To al and ex ac able hea y me al, phospho ous and
sul u concen a ions in slake g i s om he caus icizing p ocess o a pulp mill o use as a soil amendmen .
Chem. Specia . Bioa ailab. 2010,22, 87–97. [C ossRe ]
66.
Sa ka , R.; Ku a , R.; Gup a, A.K.; Mudgal, A.; Gup a, V. Use o pape mill was e o b ick making. Cogen Eng.
2017,4, 1405768. [C ossRe ]
67.
Vu, H.; Khan, M.; Chilakala, R.; Lai, T.; Thenepalli, T.; Ahn, J.; Pa k, D.; Kim, J. U iliza ion o Lime Mud
Was e om Pape Mills o E icien Phospho us Remo al. Sus ainabili y 2019,11, 1524. [C ossRe ]
68.
Li, Y.; Sun, R.; Zhao, J.; Han, K.; Lu, C. Sul a ion beha io o whi e mud om pape manu ac u e as SO2
so ben a luidized bed combus ion empe a u es. J. The m. Anal. Calo im. 2012,107, 241–248. [C ossRe ]
69.
Mäkelä, M.; Ha ju-Oksanen, M.L.; Wa kins, G.; Ek oos, A.; Dahl, O. Feasibili y assessmen o in e -indus y
solid esidue u iliza ion o soil amendmen —T ace elemen a ailabili y and legisla i e issues. Resou .
Conse . Recycl. 2012,67, 1–8. [C ossRe ]
70.
Li, H.; Niu, S.; Lu, C.; Liu, M.; Huo, M. T anses e i ica ion ca alyzed by indus ial was e - Lime mud doped
wi h po assium luo ide and he kine ic calcula ion. Ene gy Con e s. Manag.
2014
,86, 1110–1117. [C ossRe ]
71.
Shen, J.; Fa ehi, P.; Soleimani, P.; Ni, Y. Reco e y o lignocelluloses om p e-hyd olysis liquo in he lime kiln
o k a -based dissol ing pulp p oduc ion p ocess by adso p ion o lime mud. Bio esou . Technol. 2011,102,
10035–10039. [C ossRe ] [PubMed]
72.
Yin, X.; Han, P.; Lu, X.; Wang, Y. A e iew on he dewa e abili y o bio-sludge and ul asound p e ea men .
Ul ason. Sonochem 2004,11, 337–348.
73.
Hannam, K.D.; Venie , L.; Hope, E.; McKenney, D.; Allen, D.; Hazle , P.W. AshNe : Facili a ing he use o
wood ash as a o es soil amendmen in Canada. Fo . Ch on. 2017,93, 17–20. [C ossRe ]
74.
IEA Bioene gy. Op ions o Inc eased Use o Ash F om Biomass Combus ion and Co-Fi ing; IEA: Pa is, F ance, 2018.
75. Ellio , A.; Mahmood, T. Bene icial uses o pulp and pape powe boile ash esidues. Tappi J. 2006,5, 9–16.
76.
Rangan, V. Fly ash-based geopolyme conc e e. In P oceedings o he In e na ional Wo kshop on Geopolyme
Cemen and Conc e e, Mumbai, India, 28 June 2010; Allied Publishe s P i a e Limi ed: Mumbai, India, 2010;
pp. 68–106.
Appl. Sci. 2020,10, 2317 20 o 20
77.
Lessa d, J.M.; Om an, A.; Tagni -Hamou, A.; Gagn
é
, R. P oduc ion o RCC using biomass ly and bo om
ashes: F om labo a o y o ieldwo k. J. Ma e . Ci . Eng. 2017,29, 04017225. [C ossRe ]
78.
C is elo, N.; Glendinning, S.; Mi anda, T.; Oli ei a, D.; Sil a, R. Soil s abilisa ion using alkaline ac i a ion o
ly ash o sel compac ing ammed ea h cons uc ion. Cons . Build. Ma e . 2012,36, 727–735. [C ossRe ]
79.
Vu, D.H.; Wang, K.S.; Chen, J.H.; Nam, B.X.; Bac, B.H. Glass-ce amic om mix u es o bo om ash and ly
ash. Was e Manag. 2012,32, 2306–2314. [C ossRe ] [PubMed]
80.
A m, M.; Ves in, J.; Lind, B.B.; Lage k is , A.; No dma k, D.; Hallg en, P. Pulp mill ly ash o s abiliza ion o
low- olume unpa ed o es oads— ield pe o mance. Can. J. Ci . Eng. 2014,41, 955–963. [C ossRe ]
81.
Š
k
,¯
els, P.; Bonda s, K.; Plonis, R.; Ha i ono s, V.; Paegl
¯
ı is, A. Usage o Wood Fly Ash in S abiliza ion
o Unbound Pa emen Laye s and Soils. In P oceedings o he His o ical Expe ience and Challenges o
P oceedings o 13 h Bal ic Sea Geo echnical Con e ence, Vilnius, Li huaniam, 22–24 Sep embe 2016; pp. 1–4.
82.
Rios, S.; C is elo, N.; Mi anda, T.; A a
ú
jo, N.; Oli ei a, J.; Lucas, E. Inc easing he eac ion kine ics o
alkali-ac i a ed ly ash binde s o s abilisa ion o a sil y sand pa emen sub-base. Road Ma e . Pa emen Des.
2018,19, 201–222. [C ossRe ]
83.
Malakoo ian, M.; Almasi, A.; Hossaini, H. Pb and Co emo al om pain indus ies e luen using wood ash.
In . J. En i on. Sci. Technol. 2008,5, 217–222. [C ossRe ]
84.
Laohap apanon, S.; Ma ques, M.; Hogland, W. Remo al o O ganic Pollu an s om Was ewa e Using Wood
Fly Ash as a Low-Cos So ben . CLEAN Soil Ai Wa e 2010,38, 1055–1061. [C ossRe ]
85.
Das, S.K. Yudhbi Geo echnical p ope ies o low calcium and high calcium ly ash. Geo ech. Geol. Eng.
2006
,
24, 249–263. [C ossRe ]
86.
Rissanen, J.; Ohenoja, K.; Kinnunen, P.; Illikainen, M. Pa ial Replacemen o Po land-Composi e Cemen by
Fluidized Bed Combus ion Fly Ash. J. Ma e . Ci . Eng. 2017,29, 04017061. [C ossRe ]
87.
Ohenoja, K.; Tanskanen, P.; Wig en, V.; Kinnunen, P.; Kö kkö, M.; Pel osaa i, O.; Ös e backa, J.; Illikainen, M.
Sel -ha dening o ly ashes om a bubbling luidized bed combus ion o pea , o es indus y esiduals, and
was es. Fuel 2016,165, 440–446. [C ossRe ]
88.
Huo a i, N.; Tillman-Su ela, E.; Moilanen, M.; Laiho, R. Recycling o ash—Fo he good o he en i onmen ?
Fo . Ecol. Manage. 2015,348, 226–240. [C ossRe ]
89.
Fu, K.; Ren, X.Y.; Lin, J.Q.; Yue, P. Compa a i e analysis o en i onmen al impac s be ween d egs disposal
and con en ional cemen p oduc ion by li e cycle assessmen (LCA). P oc. Ad . Ma e . Res.
2013
,777,
461–466. [C ossRe ]
90.
Sa z, L.; Hamil on, I.; M
á
csik, J.; Mau ice, C.; Sädbom, S.; Wes in, G.; Bäcks öm, M. G een liquo d egs
om pulp and pape indus y used in mining was e managemen : A symbiosis p ojec (GLAD) be ween
wo Swedish base indus ies. In P oceedings o he 13 h In e na ional mine wa e associa ion cong ess,
Rauha-Lappeen an a, Finland, 31 Janua y 2017; Wolke sdo e , C., Sa z, L., Sillanpää, M., Häkkinen, A.,
Eds.; Mine Wa e & Ci cula Economy, Lappeen an a Uni e si y o Technology: Lappeen an a, Finland,
2017; pp. 862–868.
©
2020 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access
a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion
(CC BY) license (h p://c ea i ecommons.o g/licenses/by/4.0/).