Anschwemmfilter

Advanced Wastewater Treatement - a Challenge

Municipal wastewater treatment plants achieve a great deal - and yet it is important to continuously reduce selective inputs of environmentally relevant pollutants in the wastewater treatment plant effluent and their potentially negative effects on the aquatic environment. The debate on the comprehensive implementation of advanced treatment steps for the elimination of micropollutants, among other things, includes a range of technical options, which primarily include particle filtration with approaches for the adsorption or oxidation of dissolved wastewater constituents in multi-stage systems. In principle, precoat technology can be used to combine the additional reduction of dissolved trace substances and the separation of the smallest possible particles in a compact technical unit - the sewage treatment plant could become a new field of application for this technology. On a laboratory scale, preliminary tests with powdered activated carbon as a filter aid showed a high elimination performance for solids and selected trace substances. Suitable carbon products and dosing scenarios were tested and the operational management was tried out. The filter service life was also successfully increased by adding cellulose to the powdered activated carbon as a drainage aid. This significantly improves the hydraulic performance of the filter layer. At the same time, the filter layer can be adapted to different requirements via the powdered activated carbon / cellulose ratio in order to be able to react to changing operating conditions. It was shown that despite contact times in the range of seconds, elimination rates for dissolved pollutants >80 % are reliably achieved. At the same time, particles down to the submicron range were separated with high efficiency.

Pilot-scale testing at a municipal wastewater treatment plant

Following the positive results of the preliminary tests, the research team of the Institute of Sanitary and Environmental Engineering will test a pilot plant developed by HOFFMANN in the research project Anschwemmfilter - Testing and Scientific Monitoring of a Pilot-Scale Pre-Coat Filter for Wastewater Treatment as an Advanced Treatment Process for Municipal Wastewater Treatment Plants in long-term use for wastewater post-treatment at a Class V WWTP.
The following key questions will be addressed:

• How does upscaling influence separation behavior and adsoption efficency?
• How does the technology react to varying wastewater qualities?
• How stable is the filter layer and which filtering aids are most effective in continuous operation?
• How high is filtering aid consumption and what are disposal options for filtering residues?

In addition to the technical-scientific survey of key performance indicators and operating parameters, the specific process costs are determined.