CS#1 PFAS and (i)PM(T) fate and remediation in the semi-closed urban water cycle, Berlin
View of the Bode Museum, Berlin (@TTStudio/shutterstock.com)
Our aim: Ensure a secure supply of drinking water in the semi-closed water cycle
In Berlin's semi-closed urban water cycle, most drinking water is obtained via bank filtration, which is a proven nature-based solution. But as in most urban areas, the quality of drinking water sources in Berlin is challenged by PFAS and other industrial chemicals. While the presence of pharmaceuticals has been the recent focus, little is known on the contribution of different sources of PFAS and other industrial chemicals and their possible impacts on Berlin’s water supply.
Case study 1 will address this knowledge gap in several ways: along the urban water cycle, monitoring in wastewater and urban runoff is exemplarily conducted in a sub-area of Berlin to identify influencing factors that can cause contamination and are potential sources of industrial chemicals. Based on the results of the monitoring, we will use a suitable modeling approach to improve the overall management of the urban water cycle, e.g. the ability to reliably detect a wide spectrum of PFAS. In the field of drinking water treatment, the case study focuses on developing technical measures for the removal of PFAS and other industrial compounds from source water with a high content of organic matter. Further, we want to improve assessment tools for human health risks with toxicological tests and modelling.
What we have done so far...
So far, we designed prototypes of small passive samplers to be tested in surface- and wastewater monitoring campaigns. We selected a model region for the monitoring campaign in Berlin and identified suitable sampling sites using geographic information systems. Two industrial dischargers agreed on a sampling campaign at their site. First analyses revealed the presence of PFAS in both industrial wastewaters found on all three different passive samplers used.
Further, we selected a broad spectrum of adsorbents for lab-testing, completed a comprehensive adsorbent screening and set up a small-scale column test cell. We also sampled different wastewater treatment plants with advanced treatment in Germany, Sweden and Switzerland.
To detect PFAS at an even lower limit, we have developed a solid-phase extraction (SPE) method that further reduces background noise and amplifies analytes in samples of all relevant water matrices. An automatic SPE to handle multiple samples at once is also being developed. Subsequently, we will use SPE for monitoring tasks in groundwater, urban runoff, surface- and wastewater for more accurate results.
We have also completed the monitoring of stormwater runoff from two different industrial sites where 12 out of the 24 analysed PFAS were detected at elevated levels. This also means that stormwater may cause surface waters to exceed the PFAS concentration threshold. To evaluate the effect of stormwater runoff discharge to a smaller urban lake, samples were also taken from the Flughafensee lake in Berlin near a legacy contamination site. Initial results indicated that PFAS concentrations in the lake were even greater than those in the stormwater runoff. The sampling of groundwater monitoring wells around the lake is planned for further investigation.
The results from our large adsorbent screening for optimised PFAS and (i)PMT removal were evaluated and an ion exchange resin and a surface modified clay were selected to be tested in a pilot plant which started operation in February 2024. The results are compared to the performance of a large-scale Granular Activated Carbon (GAC)-plant operated at the same site in Berlin-Tegel.
