For the Luxembourgish sewage union SIDERO, Drees & Sommer Luxembourg is responsible for project management for the extension of the Mamer wastewater treatment plant.

The treatment plant was last modernized in 1998 and, due to strong population growth and the establishment of new industries and businesses, it is already operating at full capacity with regard to pollutant load. In addition, in 2015, stricter emission limits for treated water came into force, which made a new design of the plant necessary. After the modernization for the 2040 planning period, the capacity of the plant will be designed for 50,000 population equivalents (PE), which is 2.5 times the current capacity. The biggest novelty will be the use of the SBR (Sequential Biological Treatment) process for the biological treatment stage.

The treatment plant is optimally located in terms of space utilization in the narrow valley of the Mamer River and in close proximity to the European School Luxembourg. The project is expected to be completed by December 2025.