KVÄVEREDUKTION VID AVLOPPSVERKET SLOTTSHAGEN I NORRKÖPING, Nitrogen Removal at the Sewage Treatment Plant Slottshagen in Norrköping
Attempts to reduce the nitrogen content in wastewater at the sewage treatment plant Slottshagen in Norrköping have been accomplished during 1987. The plant, which takes care of the sewage from about 100,000 persons, was built for sedimentation, biological purification with activated sludge and chemical purification through post-precipitation in a separate step. After conversion of the purification process to pre-precipitation with ferric chloride, possibilities for nitrogen removal have been created. Through the pre-precipitation the compartment for chemical purification has been available for other processes and the load on the biological step has diminished. The nitrogen reduction has been accomplished through biological nitrification and denitrification. The nitrification was run on the whole water flow in the biological aeration basins. Predenitrification was run in the first parts of the aeration basins which worked as anoxic zones. “Complete abstract not presented.”