Combined Process of A~2O with Deep Aeration and MBR for Upgrading and Retrofitting of WWTP

In order to increase the treatment capacity of a county wastewater treatment plant in northwest China,from 2 000 m3/d to 5 000 m3/d,the upgrading and retrofitting were carried out.Because of construction land limit,the combined process of activated sludge process and MBR was the best choice.Based on the raw wastewater characteristics of high nitrogen and phosphorus,the A2O process was adopted in activated sludge process after the upgrading and retrofitting.In the limited land area,the effective depths of aerobic tank,anaerobic tank and anoxic tank all reached 10.5 m for achieving sufficient hydraulic retention time.The practical application results show that the effluent indexes of the combined process of A2O and MBR can reach the reclaimed water standard for toilet flushing and gardening.In costs,due to its high efficiency of oxygen use,the deep aeration used in this plant is superior to the traditional process.