POSSIBILITIES FOR INCREASED NUTRIENT REMOVAL WITH A FINAL FILTRATION STAGE

Bromma sewage treatment plant (STP) is one of three plants in Stockhol m. To meet more stringent requirements for nutrient removal the plant has been extended with a final filtration stage. Earlier it has not be en possible to operate the plant with nitrification during winter time . Bad settling properties of the activated sludge have led to bulking sludge and high concentrations of BOD and phosphorus in the effluent. With the filter stage it is now possible to reduce the load on the bio logical stage by by-passing part of the flow directly to the filters. The result has been very promising and it seems that the plant can mee t the new demands for nitrogen removal without extension of the aerate d volumes. Copyright (C) 1996 IAWQ. Published by Elsevier Science Ltd.