Interreg

Micropollutants play an increasingly important role in the design and control of municipal wastewater systems. Extensive studies have already been carried out on both the avoidance of micro-pollutants and their removal in sewage treatment plants. It is often forgotten that a significant part of micro-pollutants is already reaching water systems during heavy rainfall via sewage overflows before treatment in the sewage treatment plant can take place.

Within the framework of the Interreg VA project “Energy-neutral elimination of micro-pollutants”, advanced wastewater controle systems were therefore developed for the wastewater chains in Emmen (Netherlands) and Rheine (Germany). This made it possible to reduce the emission of micro-pollutants and micro-plastics into water bodies.
An evaluation of the existing monitoring programme for micro-pollutants showed that, in both Emmen and Rheine, the European quality standards for several micro-pollutants are exceeded in water bodies. In the further course of the project, research was carried out into the occurrence of relevant micro-pollutants in the partial flows of the Emmen and Rheine wastewater chains. While in Emmen only one waste water sub-stream showed slightly above-average concentrations of an X-ray contrast agent, in Rheine significantly larger differences in concentrations of micro-pollutants were measured. In particular in a sewage line to which a hospital was connected, compared to the average values in the respective sewage treatment plant influent.

The wastewater chain regulations developed in the course of the project in Emmen were therefore aimed at a uniform supply of wastewater to the WWTP in order to increase the removal efficiency of the WWTP, while in Rheine the aim was a targeted supply of the partial flows loaded with micro-pollutants to the WWTP. These wastewater flows were given “priority”, as it were, over wastewater flows from parts of the drainage system less affected by micro-pollutants.

Based on the knowledge gained during the project, wastewater chain regulations were developed and simulated. These were then implemented in practice. Calculations show that the measures implemented achieve a reduction in the amount of micro-pollutants emitted to water bodies. However, the exact extent of this reduction can only be determined with the help of a long-term monitoring programme. In Rheine, for example, this will be based on the numerous heavy rainfalls that will occur in the coming years. This is one of the reasons why the precipitation events are recorded in detail as part of the operational management.

Since the removal of micro-pollutants requires additional energy, the project also developed process controls for the wastewater chain (sewage and WWTP) aimed at (among other things) energy optimisation. Particular attention was paid to the integrated approach of WWTP and sewage system. The first results also point to positive effects here, although the exact quantitative effects will only become visible on the basis of longer-term monitoring.

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