A new nutrient removal system combining activated sludge with fixed biofilm was developed in this work. Fully and partially submerged rotating biological contactors (RBC) were added in the anaerobic, anoxic and aerobic reactors, respectively. The pilot-scale plant was fed synthetic municipal wastewater with the different operating parameters (i.e., hydraulic retention time, return sludge ratio and mixed liquid recycle ratio) to evaluate its performance. High degree performances of nutrient removal were obtained in the experiments. The specific substrate utilization rates in each reactor were also conducted in this work. The kinetic behaviours presented in the combined process were similar to the performance in a single sludge system. The biokinetics of a single sludge system can also be applied to the system that combines biofilm and activated sludge. Copyright (C) 1996 IAWQ.
