PERFORMANCE ANALYSIS OF ADVANCED ANAEROBIC-ANOXIC-OXIC (AAO) REACTOR FOR NUTRIENT REMOVAL IN SEWAGE

Sewage contains significant levels of nutrients, including nitrogen and phosphorus, which can severely harm aquatic ecosystems when discharged untreated. Insufficient removal of these nutrients before discharge may lead to eutrophication that will result detrimental ecological effects to the receiving water bodies. This study investigated the performance of advanced Anaerobic-Anoxic-Oxic (AAO) reactors in a full-scale application in an existing sewage treatment plant (STP) located in Kuala Lumpur where this is the first of its kind operating in Malaysia. This plant utilizes biological treatment method for nitrogen and phosphorus removal without relying on chemical precipitation that will increase the overall operation expenditure of the plant operator. Over 26 weeks, the study evaluated the plant's performance with actual sewage inflows entering the plant with an average treatment capacity of 170 million liters per day (MLD). The findings revealed removal efficiencies of 94.0% for chemical oxygen demand (COD), while nutrient removal efficiencies for Ammoniacal Nitrogen (AMN) and Total Phosphorus (TP) reached 83.9% and 86.7% respectively. The effluent concentrations for AMN, Nitrate Nitrogen (NO3-N) and TP averaged 1.7 ± 0.1 mg/L, 2.2 ± 0.7 mg/L and 0.5 ± 0.3 mg/L respectively. These results demonstrate that the advanced AAO reactor complies with Standard A effluent discharge limits for COD, NO3-N and AMN, while achieving a TP effluent concentration below 5 mg/L.