Comparative study of SMBR and extended aeration activated sludge processes in the treatment of high-strength wastewaters

Abstract

This study was conducted to compare the performance of extended aeration activated sludge (EAAS) with submerged membrane bioreactor (SMBR) systems in the treatment of high-strength wastewater under the same condition. The chemical oxygen demand (COD) concentration of the influent wastewater for the EAAS and SMBR systems was adjusted between 500–2700 and 500–5000mg/L, respectively. Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand (BOD5), total suspended solids (TSS) and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids (MLSS) and the removal efficiency of organic matter in the SMBR system were increased regularly; however, the removal efficiency of COD in the EAAS system was irregular. The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708±0.18 and 0.537±0.106, respectively. These show that the organic matter in the effluent of the SMBR system was less degradable, and thus, more biological treatment was achieved. Nitrification was completely achieved in the SMBR system, while the EAAS system could not complete the process.