Abstract
A new multi-point inflowA1/O2/A3/A4/O5 sludge-membrane coupling process and pilot plant were developed and designed to solve the problem of nitrogen and phosphorus removal of low C/N domestic sewage in southern China. By changing the distribution ratio of multi-point influent, the removal effect and transformation rule of organic matter, nitrogen and phosphorus in the system were studied. Results showed that when the average low C/N ratio of influent was 2.09 and the influent distribution ratio was 1:1, the average concentrations of COD, NH4+- N, TN and TP in the effluent were 21.31 mg/L, 0.60 mg/L, 12.76 mg/L and 0.34 mg/L, respectively, and the average removal rates are 87.3%, 98.7%, 74.1% and 88.1% respectively. When the low temperature was 12–15℃, the average removal rates were 87.3%, 98.7%, 74.1% and 88.1%, respectively. Compared with the traditional A2O process under the same conditions, the TN removal rate was increased by 15.4%, and the TP removal rate was increased by 22.2%. This system has obvious advantages in treating wastewater with low carbon and nitrogen ratio, which solved the problem that the effluent of biological phosphorus removal from low C/N ratio domestic sewage was difficult to be lower than 0.5 mg/L.