Document [original]

Citation: Eichholz, C.; Barjenbruch,

M.; Bannick, C.-G.; Hartwig, P. A

Study on the Situation and Learnings

of the Precipitant Shortage in the

German Wastewater Sector. Resources

2024,13, 1. https://doi.org/10.3390/

resources13010001

Academic Editor: Angel

F. Mohedano

Received: 30 October 2023

Revised: 1 December 2023

Accepted: 16 December 2023

Published: 21 December 2023

Licensee MDPI, Basel, Switzerland.

This article is an open access article

distributed under the terms and

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4.0/).

resources

Article

A Study on the Situation and Learnings of the Precipitant

Shortage in the German Wastewater Sector

Cora Eichholz 1,*,† , Matthias Barjenbruch 1, Claus-Gerhard Bannick 2and Peter Hartwig 3

1Department of Urban Water Management, Technical University of Berlin, 13355 Berlin, Germany

2Department of Wastewater Technology Research and Wastewater Disposal, German Environment Agency,

14195 Berlin, Germany

3Aqua & Waste International GmbH, 30177 Hannover, Germany

*Correspondence: [email protected]

†The correspondence author is also the main author.

Abstract:

Wastewater treatment companies are particularly confronted by the energy and supply

crisis resulting from the war in the Ukraine. More specifically, production and supply problems with

precipitant production have shown that today’s wastewater treatment technology in Germany is not

crisis-proofed and must become more resilient. The aim of this paper was to determine a required

precipitant quantity for Germany with regard to chemical phosphorus elimination, as well as the

expected shortfalls due to the shortage situation. Furthermore, possible solutions were identified for

how the precipitant can be saved or substituted. Study surveys were conducted to gather data for

a meaningful response regarding the operators (wastewater treatment plants, industry, and water

suppliers), manufacturers, and the German federal states. A recommendation is given on what a

path to more resilient wastewater management with a focus on phosphorus elimination could look

like. Based on the data obtained, the report focused on wastewater engineering issues for wastewater

treatment plants and industry. The results of the study are relevant for decision-makers, researchers,

and operators in the wastewater sector in order to intervene in the market themselves if necessary,

e.g., money for production or conversion to biological phosphorus elimination.

Keywords:

phosphorus; precipitant shortage; resilience of WWTPs; resilience of wastewater

treatment plants; Bio-P; biological phosphorus removal; chemical phosphorus removal; German

wastewater sector

1. Introduction

Although phosphorus (P) is a limited resource, a total of approx. 15,400 t of P per year

is discharged into German surface waters, including all input pathways [

] (p. 109), [

The urban input pathways of municipal wastewater treatment plants (WWTPs) and sewer

systems account for the largest shares [1,3].

Plant growth is promoted by P, and it has an eutrophic effect on water bodies and

coastal waters, which can lead to odor pollution when biomass dies and temperatures are

high [

]. Accordingly, P inputs have been regulated by annex 1 of the German Wastewater

Ordinance (AbwV) for size class 4 and bigger since 1989. According to this, the following

monitoring values must not be exceeded within the effluent of WWTPs:

•2 mg/L at 10,000 population equivalent (p.e.) (size class 4);

•1 mg/L from 100,000 p.e. (size class 5) [6].

The Baltic Sea area and the Northern Sea need extra protection [

]. According to the

German Surface Water Ordinance (2016), lower monitoring values may be required on

a regional and water body-specific basis. Some federal states have been implementing

stricter operating mean values [8].

Resources 2024,13, 1. https://doi.org/10.3390/resources13010001 https://www.mdpi.com/journal/resources

Resources 2024,13, 1 2 of 16

WWTPs, direct dischargers, and indirect dischargers favorably use precipitants for

the purpose of chemical phosphorus elimination (PC), as well as “support precipitants” in

biological phosphorus elimination (PBC) [9,10].

Precipitants can be used in pre-precipitation, post-precipitation, or simultaneous

precipitation, for example, in the classical aeration tank. Precipitants must be used for

advanced P elimination. This is mainly performed by the flocculation filtration process.

Phosphorus is listed as a critical raw material that is important in various ways, and

the world’s resources are finite [

]. Especially in Europe, there are only a few natural

sources. Thus, alternative efficient strategies of gaining P must be explored [

–

]. Ac-

cording to the reorientation of the German Sewage Sludge Ordinance (AbfKlärV) in 2017,

environmental and resource protection as goals moved further into focus with comprehen-

sive specifications for the recovery of P as a critical raw material [

]. Preference is the

recovery from biological phosphorus elimination (PB), since PC binds the phosphorus too

strongly to the salts, and P can only be recovered with high energy input [3].

Current developments due to the war in the Ukraine and the resulting energy and

supply crises have caused an emergency in wastewater treatment [

–

]. As early as

autumn 2022, WWTP operators have increasingly complained about supply shortages of

chemicals that are needed in particular as precipitants for PC and PBC. The use of ferric

chloride as a precipitant is widespread. Unfortunately, ferric chloride is produced as a

by-product in the titanium industry, which decreased the production immensely. While

the situation has currently eased, the supply of precipitants can be described as fragile,

and the situation of WWTPs in Germany with regard to precipitants can be described

as non-resilient.

If precipitants are not available or only available to a limited extent for the WWTP

operators, then it must be clarified to what extent precipitants can be saved or substituted.

The course of the occurring emergency situation made evident how dependent Ger-

man WWTPs are on precipitants for P. It became apparent that too little data were available

on precipitant usage in Germany in terms of type, quantity, and frequency to react sensibly

to the emergency.

In order to obtain a substantiated overview, the German Environment Agency (UBA)

commissioned a study for Germany-wide surveys on the part of operators and authorities,

as well as Europe-wide surveys on the part of manufacturers. This study was conducted

by the mentioned researchers above. The situation in the industry (direct and indirect

dischargers) and in the drinking water sector was also considered in the surveys. Based on

the data obtained, this article focused on wastewater engineering issues for wastewater

treatment plants and the industry.

2. Materials and Methods

2.1. Survey Procedure and Statistical Analysis

Data were gathered as part of the study for the German Environment Agency (UBA).

The final report of the whole study will soon be available in German via UBA Texte [19].

The study design consisted of three broad surveys, which are shortly introduced

in the following. Additionally, anonymous data of volunteering WWTPs were analyzed

regarding considerations on the German sampling regime.

The design of an online survey was chosen as the preferred method for data collection

because of its advantages, such as a larger geographical area, quicker responses, fewer

errors, and lower costs [

]. All surveys were conducted using the LimeSurvey platform

with a secured server at the Technical University of Berlin. Every survey began with its

purpose, the expected survey duration, and the assurance of anonymity and confidentiality.

All survey designs were developed specifically for the purpose of the study.

•

Survey 1: The operator survey was addressed to the municipal wastewater sector

(WWTP operators) and additionally to water suppliers, as well as indirect and direct

dischargers in Germany. The questions were specifically tailored based on the set

of rules (WWTPs or drinking water industry) for the following recipients: munici-

Resources 2024,13, 1 3 of 16

pal wastewater disposers/WWTPs, industrial dischargers, and water suppliers. The

survey link was distributed through the Federal Ministry for the Environment, Na-

ture Conservation, Nuclear Safety, and Consumer Protection (BMUV) and relevant

industry associations in Germany. The survey was addressed in German and was

administrated between 14 November 2022 and 1 January 2023. An overview of the

questions is attached in Appendix A. The questions consisted of open, as well as

semi-open, multiple-choice and grid questions. In every question, the option ‘other’

was included. The questionnaire was reviewed by the UBA before publication. Based

on the review, some questions were modified and clarified to improve their qual-

ity. After publication, two follow-up participation requests were sent to gain higher

participation in the survey.

•

Survey 2: The manufacturer survey was distributed through LimeSurvey in the

European Inorganic Coagulants Producers Association (INCOPA) and focused on the

30 biggest European manufacturers and manufacturers’ association with a possible

sales market for precipitants in Germany. The goal was to determine the produced

quantities for Germany before the precipitant shortage, the actual situation, and the

predicted future. The survey was administrated in English between 25 November

2022 and 1 January 2023. An overview of the questions is attached in Appendix B. The

questions consisted of open, as well as semi-open, multiple-choice and grid questions.

The questionnaire of survey 2 also included the option ‘other’. The survey link was

distributed through the INCOPA network, and the questionnaire was reviewed by

the UBA before publication, too. Based on the review, some questions were modified

and clarified to improve their quality. One follow-up participation request was sent

after publication.

•

Survey 3: An orienting survey of the water law decisions at the federal state offices

or ministries of the environment was carried out regarding P thresholds and sensible

water bodies in Germany. The survey addressed all federal states in Germany (survey

area), and the survey link was distributed through the BMUV like survey 1. It was

administrated in German between 30 November 2022 and 31 March 2023. The ques-

tions in the survey are attached in Appendix C. The questions consisted of open, as

well as semi-open, multiple-choice or grid questions and included the option ‘other’.

As before, the questionnaire was reviewed before publication. Based on the review,

some questions were modified and clarified to improve their quality. Three follow-up

participation requests were sent.

The responses to each survey were collected and exported to a Microsoft Excel spread-

sheet (version Office16). The software is obtained via a license from the Technical University

of Berlin. The quantitative data of the whole study were analyzed after a plausibility check

using descriptive statistics (percentages) to show the respondents’ choices. Double re-

sponses and extreme outliers were removed best as possible. Due to temporary server

overloads, duplicates and incomplete submissions may have occurred. Accordingly, only

complete submissions were considered for the evaluation. Graphical methods on the data

were employed.

2.2. Further Background Information

Furthermore, background information was collected to support the analysis and will

be listed in the following:

Destatis: The German Federal Statistical Office (Destatis) provides open access to the

wastewater treatment and the disposal database, which was used for validating the

total achievable quantity of WWTP in p.e. in Germany in survey 1 [21].

Background information of the German Association for Water, Wastewater, and Waste

(DWA), which is a politically and economically independent association, was also

used. The DWA works in expert groups designing and further developing the set of

rules for WWTP in Germany, which are not open access. For the decision of common

precipitants, the DWA-A 202 was especially used in survey 1 and 2. DWA-A 202

Resources 2024,13, 1 4 of 16

describes the set of rules for the chemical-physical processes for the elimination of

phosphorus from wastewater [22].

For the set of rules for drinking water facilities, a list of treatment substances and dis-

infection in accordance with §11 of the German Drinking Water Ordinance (TrinkwV)

version of the 24th amendment (November 2022) was used in survey 1 and 2 [23].

Detailed information on the dataset and outcomes from the web-based surveys are

accessible upon request.

3. Results

3.1. Operator Survey Regarding Use of Precipitants

The results of the operator survey with a focus on precipitant usage at WWTPs and

the industry are briefly presented. During the survey period, 2775 complete surveys

of operators were collected. Of these, some consisted of summaries of associations of

wastewater, depending on which level the survey was completed. A total of 72% of the

recipients were WWTPs, 14% were direct and indirect dischargers, and another 14% were

from drinking water facilities. The data show that especially federal states with a lot of

smaller WWTPs like Bavaria or Baden-Wuerttemberg submitted a lot of surveys (49%),

which demonstrates that a lot of plant operators participated in the survey themselves.

In total, Germany has an estimated 152,000,000 p.e. for all size classes of WWTPs. Size

classes of German WWTPs are defined in the AbwV in annex 1, part C [

]. The survey

reached 136,460,601 p.e., including WWTPs and indirect dischargers, which is 89% of the

total p.e. in Germany. The data regarding the size class of the German WWTPs showed

that 66% were in size class 4 (38,200,265 p.e.) or size class 5 (94,213,156 p.e.). The high

participation (95%) of these size classes makes sense in terms of P-elimination, since, for

size class 4 + 5 in the AbwV, P-elimination is obligatory and so is the particular concern of

the shortage of precipitants. Additionally, in size class 3 (16% in survey 1), thresholds may

exist with regard to P. Destatis lists in the open data base for wastewater treatment and

disposal in size class 4 + 5 of WWTPs a sum of 138,000,000 p.e. [

]. Accordingly, around

90% has been collected.

Regarding the industry (365 total choice), 49% are direct and 51% are indirect dis-

chargers. Furthermore, the branches of industry were queried, which could be affected

by the precipitant shortage. The collection of branches was based on annex 2–57 from the

AbwV and the Pollutant Release and Transfer Register (PRTR) [

]. Some industries chose

more than one option; therefore, in total, 368 answers were given. Branches like chemical

industry, chemical parks (summarized 19.6%), paper and pulp industry (11%), meat and

slaughter processing plants (6.25%), and milk processing (5.5%) were chosen regularly. The

most common choice of precipitants was selected on the basis of DWA A 202 and depended

on the local wastewater composition. Due to the precipitant shortage, 63% of the WWTPs

and industries switched to alternative precipitants listed in the DWA A 202, as long as the

precipitant were still available. Only 1% considered the use of alternative precipitants not

listed in the DWA A 202. The following alternatives were listed most often:

•PrecaPhos

•VTA Aluferol 91

•VTA Ferrodual

•FerroSorb

Additionally, it was asked whether there is a fear of impairment of the WWTP by

alternative precipitants. A total of 47% (1132 answers) of the operators said ‘yes’. The main

concerns most frequently cited were the risk of filamentous bacteria and bulking sludge

and an increase in hydrogen sulfide (H2S) from switching to alternative products.

Furthermore, the survey asked the type of P elimination. A total of 62,443,645 p.e.

of the WWTPs use only precipitants for eliminating P (PC), while 4,050,450 p.e. perform

PB without any precipitants and 57,690,832 p.e. PBC with precipitants as support. This

classification uses the high use of precipitants for PC or as a support.

Resources 2024,13, 1 5 of 16

For the inlet and outlet P concentrations in mg/L of the German WWTPs, including

indirect discharger 2004, answers were collected and are presented in the box and whisker

plots of Figure 1. Inlet and outlet concentrations varied regarding the mix of wastewater,

also regarding the indirect dischargers.

Resources 2024, 13, x FOR PEER REVIEW 5 of 17

• VTA Ferrodual

• FerroSorb

Additionally, it was asked whether there is a fear of impairment of the WWTP by

alternative precipitants. A total of 47% (1132 answers) of the operators said ‘yes’. The main

concerns most frequently cited were the risk of filamentous bacteria and bulking sludge

and an increase in hydrogen sulfide (H2S) from switching to alternative products.

Furthermore, the survey asked the type of P elimination. A total of 62,443,645 p.e. of

the WWTPs use only precipitants for eliminating P (PC), while 4,050,450 p.e. perform PB

without any precipitants and 57,690,832 p.e. PBC with precipitants as support. This

classification uses the high use of precipitants for PC or as a support.

For the inlet and outlet P concentrations in mg/L of the German WWTPs, including

indirect discharger 2004, answers were collected and are presented in the box and whisker

plots of Figure 1. Inlet and outlet concentrations varied regarding the mix of wastewater,

also regarding the indirect dischargers.

(a)

(b)

Figure 1. (a) Box and whisker plot P inlet concentrations in mg/L of German WWTPs. (b) Box and

whisker plot P outlet concentrations in mg/L of German WWTPs. Cross shows the average, and the

line in the box shows the median.

The median inlet concentration for P is 8 mg/L and for the outlet is 0.5 mg/L. At

maximum, according to the data of the respondents, an effluent value of 17 mg/L was

determined. This may be possible for small plants without a requirement for P

elimination. Basically, it can be stated that P elimination in Germany is very efficient. In

relation to the monitoring values, these results demonstrate a potential for precipitant

savings.

In addition to the possibility of alternative precipitants, the operator survey analyzed

the use of different precipitants and their percentage distribution in terms of number.

Precipitants, such as ferric-chloride, aluminum ferric chloride, and ferric chloride

sulphate, were used particularly frequently by the respondents before the precipitant

shortage. These are precipitants that, in addition to PC, also counteract bulking sludge

and help to reduce hydrogen sulfide (H2S) formation.

In addition to the choice of precipitants, WWTPs and direct and indirect dischargers

were asked about the average monthly quantity in tones (t) required per precipitant in

order to obtain an estimate of the quantities required per precipitant for all of Germany.

The monthly amounts were scaled up for a year and are shown in Table 1.

Figure 1.

(

) Box and whisker plot P inlet concentrations in mg/L of German WWTPs. (

) Box and

whisker plot P outlet concentrations in mg/L of German WWTPs. Cross shows the average, and the

line in the box shows the median.

The median inlet concentration for P is 8 mg/L and for the outlet is 0.5 mg/L. At

maximum, according to the data of the respondents, an effluent value of 17 mg/L was

determined. This may be possible for small plants without a requirement for P elimination.

Basically, it can be stated that P elimination in Germany is very efficient. In relation to the

monitoring values, these results demonstrate a potential for precipitant savings.

In addition to the possibility of alternative precipitants, the operator survey analyzed

the use of different precipitants and their percentage distribution in terms of number.

Precipitants, such as ferric-chloride, aluminum ferric chloride, and ferric chloride sulphate,

were used particularly frequently by the respondents before the precipitant shortage. These

are precipitants that, in addition to PC, also counteract bulking sludge and help to reduce

hydrogen sulfide (H2S) formation.

In addition to the choice of precipitants, WWTPs and direct and indirect dischargers

were asked about the average monthly quantity in tones (t) required per precipitant in

order to obtain an estimate of the quantities required per precipitant for all of Germany.

The monthly amounts were scaled up for a year and are shown in Table 1.

Germany has a high precipitant usage of ferric chloride, aluminum ferric chloride,

and ferric chloride sulphate. The yearly quantity in total regarding WWTP, including the

industry, for all precipitant is 1,103,743 t. Outliers were eliminated through a plausibility

check. The industry (direct and indirect dischargers) needs in total only 84,941 t per year.

The quantity of precipitants for WWTPs is approximately 1,015,000 t per year.

Based on the monthly quantity of necessary precipitants in t/month, the level of

precipitants in stock in t and possible new delivery (yes or no, if yes: when is the delivery

incoming and how much in t) was the shortage of precipitant calculated and scaled up to

March 2023, June 2023, and the end of 2023 in t for the worst case regarding the WWTP

and the industry. Until:

•1 March 2023 a shortage of −91,412 t;

•1 June 2023 a shortage of −186,226 t;

•The end of 2023 a shortage of −426,994 t.

Resources 2024,13, 1 6 of 16

Table 1.

Estimated quantities in t required per precipitant for WWTP, including industry, in Germany

per year.

Precipitant Estimated Quantities of Precipitant per Year

in t

Aluminum chloride 16,170

Aluminum ferric chloride 111,242

Aluminum sulphate 17,553

Aluminum ferric sulphate 4659

Ferrous chloride 61,172

Ferric chloride 667,109

Ferric chloride sulphate 74,974

Ferrous sulphate 50,125

Ferric sulphate 9418

Calcium hydroxide, white hydrated lime

(slaked lime), stabilized milk of lime 24,355

Sodium aluminate 41,602

Polyaluminum (hydroxide) chloride (PAC) 23,672

Polyaluminum (hydroxide) chloride sulphate 910

Other precipitants 767

Total for all precipitants 1,103,743

Based on the situation in January 2023.

The worst case in total for all precipitants was determined.

All data were based on the status as of 1 January 2023, and the calculation assumed

that no new sources (than mentioned) of supply are incoming. Thus, the calculation only

shows a snapshot and considers the worst-case scenario for 2023.

With no restart of production until the end of 2023, the shortage for precipitants in the

WWTP and industry sector would have been 426,994 t. The included share of industry here

was 59,430 t until the end of 2023. Consequently, without independent countermeasures

taken by operators, it would mean a considerable load of P on the water bodies. The federal

authorities under the leadership of the BMUV have regularly monitored and assessed the

situation in order to be able to intervene further if necessary.

The shortages of aluminum ferric chloride (26,930 t), ferric chloride (14,678 t), fer-

ric chloride sulphate (11,537 t), and ferrous sulphate (12,258 t) were most affected as of

March 2023.

Due to the restart of production, the worst case did not occur, although a very fragile

supply situation developed. In April 2023, the BMUV asked for an assessment of the

situation in the federal states. Most federal states reported no or no further (minority)

exceedances of the water limit values for P. However, the situation was described tense and

was not foreseeable in the long term.

As a logical consequence, an increase in costs for precipitants happened due to the

precipitant shortage. According to the survey data, 60% (1636 answers) of operators were

affected by cost increases for precipitants due to the shortage. The operators had to accept

higher prices and were unable to conclude long-term contracts. Supplies were difficult

to plan for. Respondents were asked to indicate the percentage of price increase and the

precipitant prices in 2022 compared to 2021. In some cases, the raw data included addi-

tional transport costs and energy surcharges. In addition to the desired answer format

of EUR/t, EUR/kg and even EUR/g were given. Additionally, net prices were some-

times given instead of gross prices. Predominantly, ferric chloride was referred to. The

prices were initially scaled to net prices and related to EUR/t. Outliers were removed via

plausibility check.

In Figure 2, precipitant costs for the WWTPs are considered. The query of these

questions was voluntary, and 978 respondents gave an answer. After pre-processing, the

data were transferred into a box and whisker plot.

Resources 2024,13, 1 7 of 16

Resources 2024, 13, x FOR PEER REVIEW 7 of 17

exceedances of the water limit values for P. However, the situation was described tense

and was not foreseeable in the long term.

As a logical consequence, an increase in costs for precipitants happened due to the

precipitant shortage. According to the survey data, 60% (1636 answers) of operators were

affected by cost increases for precipitants due to the shortage. The operators had to accept

higher prices and were unable to conclude long-term contracts. Supplies were difficult to

plan for. Respondents were asked to indicate the percentage of price increase and the

precipitant prices in 2022 compared to 2021. In some cases, the raw data included

additional transport costs and energy surcharges. In addition to the desired answer format

of EUR/t, EUR/kg and even EUR/g were given. Additionally, net prices were sometimes

given instead of gross prices. Predominantly, ferric chloride was referred to. The prices

were initially scaled to net prices and related to EUR/t. Outliers were removed via

plausibility check.

In Figure 2, precipitant costs for the WWTPs are considered. The query of these

questions was voluntary, and 978 respondents gave an answer. After pre-processing, the

data were transferred into a box and whisker plot.

(a)

(b)

Figure 2. (a) Percentual net cost increase of precipitants for WWTPs from 2021 to 2022. (b) Absolute

cost-increase in EUR/t of precipitants for WWTPs in net from 2021 to 2022. The cross shows the

average, and the line in the box demonstrates the median.

The median price increase for WWTPs was 63%. There was a minimum of 0%, which

was related to a long-term contract, and a maximum of 1100%, which was classified as an

outlier and eliminated from the data while pre-processing. The mean value considering

the acceptable outliers resulted in a price increase from 2021 to 2022 of 111%. In absolute

values, this means a median price in 2022 of 310 EUR/t. The mean value indicated a price

of 396 EUR/t. The upper whisker shows a range of up to 700 EUR/t without taking the

outliers into account.

For industry (see Figure 3), the median price increase was 70%, and the average was

166% (for comparison, WWTP was 63% in the median and 111% in the average).

According to the data, there was a minimum price increase of 0% and a maximum of

2246%, which was classified as an outlier and eliminated in the plausibility check.

Accordingly, the upper whisker indicated a range of price increase up to 500%. Translated

into absolute values, this means a median price in 2022 of 472 EUR/t and an average price

of 897 EUR/t (cf. WWTP 310 EUR/t median and 396 EUR/t average). Since the industry

usually buys smaller quantities from the manufacturer than large WWTPs, the higher

prices for the industry were plausible for the time being. The upper whisker shows an

absolute price range of up to 1750 EUR/t.

Figure 2.

(

) Percentual net cost increase of precipitants for WWTPs from 2021 to 2022. (

) Absolute

cost-increase in EUR/t of precipitants for WWTPs in net from 2021 to 2022. The cross shows the

average, and the line in the box demonstrates the median.

The median price increase for WWTPs was 63%. There was a minimum of 0%, which

was related to a long-term contract, and a maximum of 1100%, which was classified as an

outlier and eliminated from the data while pre-processing. The mean value considering

the acceptable outliers resulted in a price increase from 2021 to 2022 of 111%. In absolute

values, this means a median price in 2022 of 310 EUR/t. The mean value indicated a price

of 396 EUR/t. The upper whisker shows a range of up to 700 EUR/t without taking the

outliers into account.

For industry (see Figure 3), the median price increase was 70%, and the average was

166% (for comparison, WWTP was 63% in the median and 111% in the average). According

to the data, there was a minimum price increase of 0% and a maximum of 2246%, which

was classified as an outlier and eliminated in the plausibility check. Accordingly, the upper

whisker indicated a range of price increase up to 500%. Translated into absolute values,

this means a median price in 2022 of 472 EUR/t and an average price of 897 EUR/t (cf.

WWTP 310 EUR/t median and 396 EUR/t average). Since the industry usually buys smaller

quantities from the manufacturer than large WWTPs, the higher prices for the industry

were plausible for the time being. The upper whisker shows an absolute price range of up

to 1750 EUR/t.

Furthermore, all recipients (WWTPs, industry, and drinking water facilities) were

asked for procedural adjustments to reduce precipitants at their plants. The section was

mandatory, and a total of 21% of all respondents performed procedural adjustments.

Regarding the 2159 answers saying ‘no’, 1436 belonged to WWTPs in size class 4. It was

assumed that most plants operated PC and could not switch to other measures at short

notice due to the size of the WWTP. A total of 425 respondents from WWTPs gave additional

information regarding possibilities for procedural adjustments and an estimation for the

reduction of precipitants in percentages (most relevant listed in Table 2). Multiple responses

were possible.

The avoidance of overdosing was indicated as a particularly common measure. A

percentage precipitant reduction of 5–75% was estimated depending on the plant. The

approximation with the threshold was often mentioned with the same goal and the same

estimation for the precipitant reduction. Furthermore, switching to PB was listed as a

process engineering adjustment. Here, a savings effect of 3–90% was estimated depending

on the performance of the WWTP so far. Many adjustments could also aim to optimize and

automate dosing, as well as online P measurement.

Resources 2024,13, 1 8 of 16

Resources 2024, 13, x FOR PEER REVIEW 8 of 17

(a)

(b)

Figure 3. (a) Percentual net cost increase of precipitants for the industry from 2021 to 2022. (b)

Absolute cost increase in EUR/t of precipitants for the industry in net from 2021 to 2022. The cross

shows the average, and the line in the box shows the median.

Furthermore, all recipients (WWTPs, industry, and drinking water facilities) were

asked for procedural adjustments to reduce precipitants at their plants. The section was

mandatory, and a total of 21% of all respondents performed procedural adjustments.

Regarding the 2159 answers saying ‘no’, 1436 belonged to WWTPs in size class 4. It was

assumed that most plants operated PC and could not switch to other measures at short

notice due to the size of the WWTP. A total of 425 respondents from WWTPs gave

additional information regarding possibilities for procedural adjustments and an

estimation for the reduction of precipitants in percentages (most relevant listed in Table

2). Multiple responses were possible.

Table 2. Possibilities of process engineering adjustments for precipitant reduction and an estimated

reduction in precipitants in percentages for WWTPs (n = 435).

Possibilities of Process Engineering Adjustments

Number of WWTPs

% Reduction Precipitants

Average

Min

Max

Avoidance of overdosing

109

Approximation with threshold value

Online P measurement

Stretch mode operation for precipitants

Automation

Optimization PB

Optimization precipitant addition

Change of the dosing point

Load-related regulation

2-point precipitation

Optimization aeration

Manual operation of the dosing, minimum dosing

Alternative precipitant

Additional C-Source

Figure 3.

(

) Percentual net cost increase of precipitants for the industry from 2021 to 2022. (

) Abso-

lute cost increase in EUR/t of precipitants for the industry in net from 2021 to 2022. The cross shows

the average, and the line in the box shows the median.

Table 2.

Possibilities of process engineering adjustments for precipitant reduction and an estimated

reduction in precipitants in percentages for WWTPs (n= 435).

Possibilities of Process

Engineering Adjustments

Number of

WWTPs

% Reduction Precipitants

Average Min Max

Avoidance of overdosing 109 25 5 75

Approximation with

threshold value 55 54 5 75

PB 52 26 3 90

Online P measurement 46 19 5 40

Stretch mode operation for

precipitants 45 29 5 75

Automation 33 18 5 45

Optimization PB 25 20 3 60

Optimization precipitant

addition 25 16 2 30

Change of the dosing point 9 13 2 30

Load-related regulation 9 16 10 25

2-point precipitation 7 16 10 25

Optimization aeration 7 36 10 70

Manual operation of the

dosing, minimum dosing 6 13 5 30

Alternative precipitant 5 43 80 20

Additional C-Source 2 40 30 50

In the industry sector, 32 respondents answered this question. Table 3shows the

possibilities of process engineering adjustments on the part of the industry. Multiple

responses were possible. Again, avoidance of overdosing and automation were frequently

selected as adaptation strategies. In general, a distinction must be made between short-,

medium-, and long-term measures for adaptation strategies, irrespective of the query

area. In the area of the WWTPs, as well as in the industry, some measures were named in

each case.

Resources 2024,13, 1 9 of 16

Table 3.

Possibilities of process engineering adjustments for precipitant reduction and the estimated

reduction in precipitants in percentages for the industrial sector (relevant n= 31).

Possibilities of Process

Engineering Adjustments

Number of

Industry Plants

% Reduction Precipitants

Average Min Max

Avoidance of overdosing 7 22 7 75

Automation 6 18 6 25

Stretch mode operation

for precipitants 4 14 4 20

Usage of alternative processes 4 28 3 100

Blending with other water streans

3 18 3 40

Alternative precipitant 3 31 3 100

PB 2 18 2 33

Optimization of process 2 24 2 50

3.2. Manufacturing Survey Regarding Production of Precipitants for the German Market

During the manufacturing survey, 11 of 30 possible survey submissions from manufac-

turers within the INCOPA were made. These 11 participants had, altogether, 25 production

sites in European countries. Those sites delivered precipitants to Germany as well. Seven

production sites were directly in Germany, and three sites were in France. Two production

sites were in Norway. Otherwise, there was one production site each in Belgium, Czech

Republic, Denmark, Estonia, Finland Greece, Italy, Poland, Portugal, Slovakia, Slovenia,

Spain, and Sweden.

Regarding the question whether the manufacturers produce precipitants for wastewa-

ter treatment for Germany, 82% answered ‘yes’. Furthermore, 45% produced precipitants

for drinking water treatment in Germany. Since not all members of the INCOPA network

answered, it cannot be conclusively answered whether the other members also produced

precipitants for Germany in the drinking water or wastewater sector.

In addition, the manufacturers were asked how much they normally produce on

average per precipitant in the wastewater sector (based on DWA A 202), how much they

currently produce, and what production volume is expected within the next 6 months.

Based on these data, the annual production volume for Germany per precipitant was

estimated, and the percentage output of production at present and in the future was

calculated. In summary, in Table 4, the annual production volume for the wastewater sector

of the six most produced precipitants is shown. In addition, with regard to the current

and expected performance, a trend was estimated in each case on the basis of the annual

average production quantity and was additionally visualized using arrows. The trend

shows a rising (green, ascending arrow) or falling (red, falling arrow) trend.

For many precipitants, and especially for the iron-based precipitants, a decreasing

production was investigated regarding the survey. For aluminum chloride and aluminum

sulfate, however, an increasing production was observed. It can be seen that some producers

switched to the production of other precipitants, and some precipitants produced more.

With regard to aluminum sulfate, production was even expected to continue to increase

within the next 6 months. For ferrous chloride and ferric chloride, an easing and renewed

increase in production was expected within the next 6 months at the time of the survey.

Related to the wastewater sector, an annual total volume of all precipitants of 583,740 t/a

could be provided according to the survey. This represents approximately 50% of the

precipitants required per year (1,103,734 t/a) for WWTPs and the industry (see Survey 1).

As reasons for limited production (wastewater and drinking water sector answered

combined) the manufacturers mentioned most often the lack of raw materials (e.g., hy-

drochloride acid) and the dependence of the titan production.

Resources 2024,13, 1 10 of 16

Table 4.

Annual production volume of the 6 most produced precipitants in tones for Germany, and

the current and expected volume with trends for the next 6 months regarding the shortage.

Precipitants

Wastewater

Treatment

Average

Quantity

per

Month

Yearly

Average

Quantity

Current

Quantity

per

Month

Capacity

Current

Situation

Trend

Current

Situation

Medium-

Term (within

6 Months)

Quantity per

Month

Forecast

Amount

for 6

Months

Percentage

Forecast of

Yearly

Amount

Expected

Trend

[t/Month] [t/Year] [t/Month] [%] [-] [t/Month] [t/(6

Month] [%] [-]

Aluminum

sulphate 4225 50,700 8925 211%

Resources 2024, 13, x FOR PEER REVIEW 10 of 17

Table 4. Annual production volume of the 6 most produced precipitants in tones for Germany, and

the current and expected volume with trends for the next 6 months regarding the shortage.

Precipitants

Wastewater

Treatment

Average

Quantity

per Month

Yearly

Average

Quantity

Current

Quantity

per Month

Capacity

Current

Situation

Trend

Current

Situation

Medium-Term

(within 6

Months)

Quantity per

Month

Forecast

Amount

for 6

Months

Percentage

Forecast of

Yearly

Amount

Expected

Trend

[t/Month] [t/Year] [t/Month]

[%] [-] [t/Month]

[t/(6

Month]

[%] [-]

Aluminum

sulphate

4225 50,700 8925 211%

7250 43,500 86%

Ferrous

chloride

6550 78,600 3970 61%

15,950 95,700 122%

Ferric chloride 9440 113,280 9200 97%

10,100 60,600 53%

Ferric chloride

sulphate

8000 96,000 2040 26%

40 240 0%

Ferrous

sulphate

3500 42,000 1870 53%

0 0 0%

Polyaluminum

(hydroxide)

chloride (PAC)

11,120 133,440 9120 82%

10,220 61,320 46%

Based on the shortage situation in January 2023. Data for aluminum chloride, aluminum ferric

chloride, aluminum ferric sulphate, ferric sulphate, sodium aluminate, and polyaluminum

(hydroxide) chloride sulphate were also gathered. Calcium hydroxide, white hydrated lime and

stabilized milk of lime were investigated as well, but no data could be collected.

For many precipitants, and especially for the iron-based precipitants, a decreasing

production was investigated regarding the survey. For aluminum chloride and aluminum

sulfate, however, an increasing production was observed. It can be seen that some

producers switched to the production of other precipitants, and some precipitants

produced more. With regard to aluminum sulfate, production was even expected to

continue to increase within the next 6 months. For ferrous chloride and ferric chloride, an

easing and renewed increase in production was expected within the next 6 months at the

time of the survey. Related to the wastewater sector, an annual total volume of all

precipitants of 583,740 t/a could be provided according to the survey. This represents

approximately 50% of the precipitants required per year (1,103,734 t/a) for WWTPs and

the industry (see Survey 1).

As reasons for limited production (wastewater and drinking water sector answered

combined) the manufacturers mentioned most often the lack of raw materials (e.g.,

hydrochloride acid) and the dependence of the titan production.

Furthermore, respondents were asked whether transport costs for manufacturers

increased in the current situation. A total of 91% of the respondents stated that they had

been affected by higher costs. The increase varied between 15 and 35% regarding 2021,

i.e., within one year (query status at the end of 2022).

In summary, precipitant manufacturers were affected differently by the production

bottlenecks. Some industries had or have no bottlenecks at all, while others switched to

the production of alternative precipitants. The main problem identified was the non-

availability of raw materials and auxiliary materials. Currently, some major precipitant

manufacturers started producing again but at stockpiles and still very high prices for the

consumer (WWTPs and indirect and direct dischargers).