Abstract

Combining sludge hydrolysis with predenitrification is a promising method to remove nitrogen and decreased use of external carbon content in wastewater. The Klagshamn wastewater treatment plant plans to alter the primary settler into an in-line hydrolysis basin with subsequent predenitrification to reduce the nitrate load into the overstrained moving-bed biofilm reactor. A reference scenario, which included annual data from the process control system, was established and calibrated with the operational findings from the plant in 2007 to form a dynamic wastewater model. A method for generating a complete annual data set based on laboratory values was established and implemented with the model. The simulated results agreed well with Klagshamn’s actual operation. In addition, the simulated results of the proposed in-line hydrolysis basin were used to evalu-ate the potential for predenitrification. The results with hydrolysate showed that an additional 40 t·a-1  of nitrogen could be denitrified compared to the reference scenario.