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 [
6]. 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. [
21]. Accordingly, around 90% has been collected.
Regarding the industry (365 total choice), 49% are direct and 51% are indirect dischargers. 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) [
24]. 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.
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.
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.
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), ferric 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 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.
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.
In the industry sector, 32 respondents answered this question.
Table 3 shows 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.
3.2. Manufacturing Survey Regarding Production of Precipitants for the German Market
During the manufacturing survey, 11 of 30 possible survey submissions from manufacturers 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 wastewater 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., 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).
3.3. Orienting Survey of the Water-Law Allowances
The orienting survey of the water-law allowances regarding P thresholds with the federal state offices and/or environmental ministries ran until 31 March 2023. Using the LimeSurvey platform, seven complete submissions were received, including Baden-Wurttemberg (BW), Saarland (SL), Saxony-Anhalt (ST), Saxony (SN), Schleswig-Holstein (SH), Hamburg (H), and Thuringia (TH). In addition, outside of the survey, five states submitted information by mail to the question ‘How many WWTPs have lower limiting values than those specified in the Wastewater Ordinance?’, which are Lower Saxony (NI), Berlin (B), North Rhine-Westphalia (NW), Bavaria (BY), and Rhineland-Palatinate (RP). In total, 12 of 16 federal states were covered through the survey with regard to P limits. Accordingly, the remaining survey questions could only be evaluated for the seven federal states in LimeSurvey.
Concerning the question whether inquiries/requests for help of the operator had already been received at the time queried, all federal states said ‘yes’. Operators reached out to the authorities. To the further question of whether transgressions with regard to the water law allowance were indicated, 57% (four federal states) answered ‘yes’, and 43% answered ‘no’ (three federal states).
Based on the situation at the end of March, no actions to set the allowance up to the monitoring value had been taken.
The explanations for no actions were, in general:
Tolerance of non-compliance with the values of the notice was pronounced based on the presentation of appropriate justifications.
Despite scarcity, the monitoring value was complied with so far.
Alternative actions have been mentioned in this context:
Stretching operation (by the operators).
Deviation from target values at wastewater treatment plants with further measures. (by the operators).
Exchange between operators and authorities.
Information on documentation and notification obligations in the event of precipitant shortages (by the authorities).
Coordination of saving options (by the authorities).
Use of alternative precipitants (by the operators).
One federal state could imagine adjusting the permit over the winter period due to the expected lower algae growth.
Furthermore, the wish to establish a central information platform on the supply situation and opportunities for substitutes was mentioned.
Federal states with sufficient and comparable raw data were compared in
Table 5. It considers the federal states with regard to lower monitoring values than in the Wastewater Ordinance. The focus was on sensitive water bodies.
Since, in some responses, the smaller size classes were summarized differently, these are summed up here for size class 3 + 2 + 1. It can be seen that, even for WWTPs of this size, 376 plants already had to comply with P limits smaller than 2 mg/L in the effluent due to sensitive water bodies. Most plants were affected by stricter discharge limits in BY. In NW, the majority of plants (117) in size class 5 were classified with discharge limits smaller than 0.5 mg/L. Overall, a very diverse picture emerged for the participating federal states. A classification according to minimum and maximum values was not possible in a way due to the different data transmission.
Furthermore, the number of sensitive waters of participating federal states is summarized in
Table 6. Since not all federal states submitted data, or submitted incomplete data, this does not correspond to the total number of P-sensitive waters for Germany.