An JY  Kwon JC  Kim YH  Jeng YH  Kim DE  Ryu SH  Kim BW

Upflow Multi-Layer Bioreactor (UMBR) Kwon's nutrient removal (KNR) biological nutrient removal (BNR) dual sludge small sewage treatment plant

A simple dual sludge process, called as KNRⓡ (Kwon's Nutrient Removal) system, was developed for small sewage treatment. It is a hybrid system that consists of an UMBR (Upflow multi-layer bioreactor) as anaerobic and anoxic reactor with suspended denitrifier and a post aerobic biofilm reactor, filled with pellet-like media, with attached nitrifier. To evaluate the stability and performance of this system for small sewage treatment, the pilot-scale KNRⓡ plant with a treatment capacity of 50 m3/d was practically applied to the actual sewage treatment plant, which was under retrofit construction during pilot plant operation, with a capacity of 50 m3/d in a small rural community. The HRTs of a UMBR and a post aerobic biofilm reactor were about 4.7 h and 7.2 h, respectively. The temperature in the reactor varied from 18.1℃ to 28.1℃. The pilot plant showed stable performance even though the pilot plant had been the severe fluctuation of influent flow rate and BOD/N ratio. During a whole period of this study, average concentrations of CODCr, CODMn, BOD5, TN, and TP in the final effluent obtained from this system were 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, and 0.87/0.17 mg/L (with/without poly aluminium chloride(PAC)), which corresponded to a removal efficiency of 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, and 55.4/90.3%, respectively. Excess sludge production rates were 0.026 kg-DS/m3-sewage and 0.220 kg-DS/kg-BOD lower 1.9 to 3.8 times than those in activated sludge based system such as A2O and Bardenpho.