Performance and Evaluation of the Inverted A2/O process used for municipal wastewater treatment

Based on the monitoring of the main water quality parameters in the inverted A² / O process employed in The No.4 Wastewater Treatment Plant of Xi´an City, this paper mainly analyzed contaminant removals during over half a year operation. The results demonstrated that the total removal efficiencies of CODcr, TN, NH₃-N, TP and SS could reach to 90.5%, 65.2%, 82.0%, 54.8% and 95.8%, respectively. In addition, the treatment process showed a strong resistance for loading impact, resulting in relatively stable effluent quality. However, a lower removal efficiency of TP in the bioreactor and sludge floating in the secondary settling tank were observed. Through deep analyzing, some countermeasures were suggested. Therefore, it is expected that the conclusions derived from this study may be valuable for design and operation management of the similar Wastewater Treatment Plants in the future.