Evaluation of Advanced Anaerobic Anoxic Oxic (AAO) Biological Treatment System for Nutrient Removal in Sewage

Abstract Sewage contains nutrients such as nitrogen and phosphorus where unregulated discharge can detrimentally impact to aquatic ecosystem. Failure to adequately remove these nutrients from sewage prior to discharge could promote eutrophication, resulting in adverse ecological consequences for the receiving water bodies. A study was conducted to evaluate the performance of the advanced AAO reactors in a full-scale application at Pantai Dalam, Kuala Lumpur, marking the first implementation of this treatment process in Malaysia. This plant has the capability of removing nitrogen and phosphorus via biological treatment using anaerobic reactor without additional of chemical percipitation. The study was conducted for 180 days with actual sewage flow entering the plant, with four (4) reactors being put into operation with an average treatment capacity of 170 MLD. The results demonstrated that removal efficiencies reached 96.7% for BOD 5 and 94.0% for COD, while nutrient removal efficiencies for AMN and TP were 83.9% and 86.7%, respectively. The effluent concentration for nutrient removal for AMN and TP was on average 1.7 ± 0.1 and 0.5 ± 0.3 mg/L respectively. The results indicate that the advanced AAO reactor meets the effluent discharge Standard A requirements for BOD 5 , COD and AMN, and is also capable of achieving a TP effluent concentration of less than 5 mg/L.