Characteristics of rural domestic sewage processed with contact oxidation-enhanced coagulation in Chongming island

In accordance with the characteristics of low carbon source and comparative high nitrogen and phosphorus concentration, contact oxidation-enhanced coagulation combined process was adopted to treat the rural distributed wastewater of Chongming island. Furthermore, the effects and mechanism of this process was studied. The results showed that the effluent quality was COD<50 mg/L, NH3-N<5 mg/L, TN<20 mg/L and TP<0.5 mg/L, meeting the first standard of GB18918-2002. The mechanism of pollutants removal depended on kinds of analytical ways. From the results of GC-MS, the biological technology could well treat the alkane, arene and heterocyclic compounds; the removal of TN was attributed to simultaneous nitrification and denitrification indicated by the accumulation of nitrite; dissolved phosphorus could be treated by chemical precipitation while non-orthophosphate by adsorption. Moreover, the combined process exhibited advantages such as small land occupation, low cost, easy maintenance and management. It was suitable for treatment of the domestic sewage in rural areas.