Upgrading of a Small Wastewater Treatment Plant by Lamellar Settler and Tertiary Moving Bed Biofilm reactor

This paper focuses on a small wastewater treatment plants that has been upgraded with a lamellar settler and a tertiary MBBRTM tank. The plant was originally built for 120 m3/d, 60 kgCOD/d, 30 kgBOD/d and 6 kgN/d; effective incoming loads were 290 m3/d, 81 kgCOD/d, 46 kgBOD/d and 10 kgN/d. The screen was replaced, the static settler was transformed into a lamellar settler, the existing sludge thickener was converted in a tertiary nitrification MBBRTM tank, and a new prefabricated thickener was installed. After this upgrading, with loads of 244 m3/d, 49 kgCOD/d, kg 33 kgBOD/d and 7 kgN/d, the plant removed 87% of COD, 94% of BOD, 99% of TKN and 46% of Tot-N. These results confirm that lamellar settlers and MBBRTM tanks are good solutions to upgrade small wastewater treatment plants without building new tanks.