Optimization of A2/OmMBR Integrated Process for High Standard of Reclaimed Water Quality in Beijing, China

Abstract

Abstract. The effectiveness of A 2 /O-MBR integrated process has been studied for domestic wastewater reclamation to meet the latest Beijing pollutant emission standards. Experimental results showed that high DO concentrations in the aerobic tank improved COD Cr , NH 3 -N, and TP removals, whereas the TN removal increased initially and then decreased. Increasing the internal reflux ratio promoted the removal of TN, howbeit negligibly affected the removals of COD Cr , NH 3 -N, and TP. The removals of COD Cr , NH 3 -N, and TN rose with HRT, but the extent of rising became limited as HRT larger than 9 h. Membrane fouling rate increased with running time, and accelerated by improving membrane flux. When the system parameters are set at optimized conditions, i.e. the DO concentration of 2.0 mg/L, the internal reflux ratio of 250%, HRT of 9 h, and ozonation for 20 min, the major water quality of outlet remains stable and meets Grade A of Beijing local standards for new wastewater treatment plant (DB 11890-2012).