Potential of the compact extended aeration reactor (CEAR) as an integrated system to biologically degrade municipal sewage according to Malaysian regulatory limits: Design, process and performance

Abstract

A laboratory scale integrated biological reactor was designed and fabricated to perform organic removal, nitrification and denitrification from synthetic sewage with the C:N:P ratio 100:10:2. The configuration of the reactor is anoxic – aeration and anoxic with a settler, integrated within one system. A suspended growth medium guarantees adequate organic and nutrient removal, in a continuous flow stirred chamber reactor (CFSTR). The arrangement resembles the Bardenpho process, which combines Wuhrmann’s and modified Ludzak-Ettinger processes. The purpose is innovation to provide a minimal footprint to make the system modular, user friendly, with easy operation and maintenance compared with conventional methods. Similarly, the aim is to attain the Department of Environment (DOE) Malaysia revised Environment Quality Regulation Act 2009 (EQA, 1974) review on ammonia, nitrate and phosphorus discharge limits by reducing negative impacts due to discharge into receiving water bodies. Effluent ammonia and nitrate limits were set at a minimum of 5 mg/L and 10 mg/L, respectively. The removal of phosphorus was inadequate because phosphorus requires an anaerobic process. The reduction of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonia-nitrogen (NH4-N), nitratenitrogen (NO3-N), total phosphorus (TP) and total suspended solids (TSS) were achieved at 92.8%, 89.5%, 81%, 66%, 23% and 92.5%, respectively. The removal of ammonia and nitrate-nitrogen were enhanced within the last phase at 90.2% and 80% reduction, respectively.