Effect of Disc Rotating Velocity on the Nitrification Performance of RBC System and Biofilm Kinetics

Abstract

Nitrification of high strength ammonia wastewaters in a rotating biological contactor (RBC) system was studied at 5 rpm, 15 rpm and 20 rpm disc rotating velocities. Effect of disc rotating velocities on the performance of the RBC system and biofilm kinetics was observed. Flow rates were changed from 19.6 to 103.5 l day⁻¹ giving hydraulic retention times of 0.28 to 1.5 days. Influent NH₄-N concentrations were changed from 100 to 550 mg l⁻¹. For certain applied NH₄-N loading rates and bulk NH₄-N concentrations, rotating velocity of discs affected NH₄-N removal rate and biofilm kinetics in the RBC system. If NH₄-N removal efficiency and NO₂-N concentration in the effluent were considered, RBC system was more efficient at 15 rpm disc rotating velocity at about 6 g NH₄-N m⁻² day⁻¹ applied NH⁴-N loading rates. NH₄-N removal rate of the RBC system at 5 rpm, 15 rpm and 20 rpm disc rotating velocities was nearly equal at applied NH₄-N loading rates up to about 3.5 gNH₄-N m⁻² day⁻¹.