Trace organic compounds (TroC) are found since decades in all waters, influenced by human activities and consumption of chemicals for a great diversity of purposes. The concentration levels found differ, but are mostly in the range of a few ng/l to 100 and more µg/l (for a few substances), thus they are also called organic micropollutants, OMP. The total number of identified substances is in the range of several thousands and is still increasing, however not all are at the same time in a given water sample. Even though they are most probably present in the market for a number of decades and thus in the water bodies, some authors call them “emerging organic pollutants”, which is not correct. They emerge in the analytical methods as peaks, due to the rapid development of advanced chemical methods like the HPLC-MS/MS and nowadays with the high-resolution mass spectrometer (HRMS), applied in the Non-Target-Screening for unknown substances and for Suspected-Target-Analysis for projected metabolites. The most recent data base for Non-Target-Screening includes now about 10.000 specific substances.
Due to many studies on the occurrence of TroC it became obvious, that there are many different sources, one of them are secondary effluents of domestic and industrial wastewaters. These are point sources, which are definitely influencing the receiving water bodies, up to the drinking water production from these imparted sources. The dilution is frequently not sufficient to lower the concentrations enough for surface water and drinking water production.
The advanced treatment of secondary effluents for TroC-removal is one feasible approach to reduce the impact. The ongoing studies at pilot and full scale in Switzerland and parts of Germany rely on the use of ozonation for TroC-oxidation, followed by a biofiltration or on adsorption of TroC on powdered and/or granular activated carbon. Both techniques are well adapted in advanced drinking water treatment for 50 years, due to early pollution. The lecture will show the benefits and limitations of these different approaches to TroC-removal, including the case of Berlin, where sewage plants are situated up-stream of drinking water sources and where bank filtration and groundwater recharge are traditional and natural treatment systems.
Martin Jekel is a Full Professor of Water Quality Control at the Department of Environmental Science and Technology at the Technical University of Berlin.