Lotwater - Innovative demonstration project for local treatment of combined sewer overflows enabling the implementation of the Water Framework Directive

The objective of the project was to demonstrate a full-scale treatment technique for combined sewer overflows resulting from wet weather discharges, using a lamella separator, providing a cost-efficient tool for achieving the objectives of improving the quality of surface waters, as laid down in the WFD. The project studied 3 types of emissions from combined sewer overflows: discharges from a large catchment to a bathing water area (testing in Copenhagen advanced filters and UV-disinfection); discharges from a large catchment to a large river/lake (testing in Odense turbofloc systems and lamella separators); and discharges from a small catchment to a small water course (testing in Aarhus novel structure design and lamella separators). Conclusions show that technologies tested are cost-efficient when installed at large catchments. For catchment sizes below 25 connected paved hectares the construction of detention volume is generally still cost-efficient.