Cyclic activated sludge technology : recent operating experience with a 90,000 p.e. plant in Germany

Cyclic activated sludge technology was selected for the Potsdam Wastewater Treatment Plant (90,000 p.e.). The cyclic activated sludge facility comprises four modules integrated into two circular basins. Construction was commenced in February 1998 with seeding of the plant for start up taking place in October 1998. Process performance has been met since Spring 1999 at 80-90% of design load. In order to optimize start-up procedures, respiration rates were used as a guidance for process stabilization and online process optimization during normal operation. Operation for co-current nitrification denitrification provided an ammonia removal of 1.1 mg NH4-N/g MLSS.h (15 degrees C) and a corresponding nitrate respiration rate of 0.85 mg NO3-N/g MLSS.h under aerated conditions. Enhanced biological phosphorus removal generated an effluent mean total phosphorus concentration of 0.38 mg/L without precipitant addition.