Combined Processes

In principle, the different treatment processes can be combined with one another, and numerous process combinations are conceivable. In particular, the combination of adsorptive and oxidative processes (ozonation followed by granular activated carbon (GAC) adsorption) is considered very promising and is already applied at several municipal wastewater treatment plants (e.g., the Überlinger See wastewater treatment plant). By combining two processes, ozonation can be operated at lower ozone dosages compared to stand-alone operation. In addition, the service life of the GAC adsorber is extended due to the preceding ozonation step, meaning that the activated carbon needs to be replaced or regenerated less frequently.

In addition to oxidative and adsorptive processes, physical treatment processes are also potentially suitable for the removal of micropollutants. In this context, membrane filtration processes such as nanofiltration or reverse osmosis are of primary relevance. Both processes are used in drinking water treatment. However, in municipal wastewater treatment, their application is currently considered unsuitable due to a lack of operational experience, the disposal challenges associated with the resulting concentrate stream, and the high energy demand required for operation.