Nitrogen and Phosphorus Removal of Modified A2/O Process on Low-Carbon Domestic Sewage under Low Temperature

Abstract

A modified compound multiple-influent A2/O process was used to treat sewage with a low C/N under low temperature, the nitrogen and phosphorus removal was investigated. Raw water was distributed into anaerobic tank and anoxic tank by the proportion of 5:5 to rationally distribute the carbon sources required by anaerobic phosphorus release and anoxic denitrification. And some carriers were added into aerobic tank and anoxic tank separately to stabilize the effect of nitrification and denitrification and improve the denitrification efficiency. The effluent of anaerobic tank and anoxic tank flowed into aerobic tank to reduce the sludge flow path. In order to increase microbial biomass, adjust sludge return ratio was ranged from 50% to 75%. The results showed that when the water temperature is14°C, the concentration of COD, NH3-N, TN and TP in influent were 69.5 mg/L, 33.74 mg/L, 42.31 mg/L and 4.94 mg/L, the effluent quality of the above indexes were 40.1 mg/L, 1.45 mg/L, 12.54 mg/L and 0.46 mg/L, and the average removal of COD, NH3-N, TN, TP were 85.10%, 95.7%, 70.37% and 90.73%, respectively.