Technologies for the Elimination of Micropollutants in Municipal Wastewater Treatment Plants – Strategy for Bavaria

Abstract

In order to give recommendations for a large-scale implementation of a fourth purification stage at Bavarian WWTPs, existing technologies for the elimination of anthropogenic micropollutants in municipal wastewater treatment plants were evaluated on behalf of the Bavarian Environment Agency (LfU). Based on the currently available technologies, 13 WWTPs with an active fourth treatment step were investigated (Baden-Württemberg and North Rhine-Westphalia) and parameters relevant for dimensioning and operation were documented. Subsequently the different technologies were compared in terms of purification capacity, efficiency and usability, evaluating the suitability as solution for WWTP considering boundary conditions in Bavaria. For a large-scale implementation on Bavarian WWTPs, adsorption and oxidation processes are recommended. It should be noted, that only in exceptional cases Bavarian WWTPs of size classi fication 4 and 5 have a sand filter stage as a final cleaning process. Considering that, an ozonization step combined with downstream granulated activated carbon filter or a downstream biological treatment step seem to be the most practicable alter native for the implementation of a Bavarian pilot plant. Finally, the selection of a suitable purification process in consideration of the local conditions of a WWTP should always be examined in each in dividual case. The decision making essentially depends on the existing usable process steps. On the basis of the current state of knowledge, the back fitting of wastewater treatment plants (WWTP) with an advanced treatment step/fourth treatment step such as ozonization or activated carbon is not mandatory. Nevertheless a back fitting can be necessary in well founded particular cases.