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According to statistics, more than 80 million tons of sewage is produced every year in rural areas in China. Most discharged untreated sewage results in serious pollution of living environment and surrounding water, and it also seriously threatens drinking water security and the health of farmers.The experiment studied that combined process(ABR-vertical subsurface flow constructed wetland)treated rural sewage. The test results are as follows:At a temperature of 10～15℃, influent COD concentration of 214-452mg/L, HRT of 48h, aerobic sludge of oxidation ditch was inoculated,and ABR reactor started start-up. It lasted 96 days, and at a HRT of 24h, COD removal efficiency was basically stabilized above 90%, start-up of anaerobic reactor was successful. Higher activity of inoculated sludge, proper organic loading and hydraulic loading, and relatively higher alkalinity are the key to successful start-up of reactor.At a temperature of 21～28℃, HRT of above 12h, ABR treated domestic water, COD average effluent concentrations were below 100mg/L and were qualified to StandardⅡof "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant". At a HRT of 18h,12h, COD average effluent concentration was 43mg/L, which was qualified to Standard A of "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant". At a HRT of 8～4h, average removal efficiencies were below 50%, average effluent concentrations were above 160mg/L.So it needed further treatment.At room temperature, HRT of above 12h, COD average effluent concentrations were below 50mg/L, which were qualified to Standard A of "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant". At a HRT of 8～4h, average effluent concentration were below 150mg/L.Nitrogen, phosphorus removal effects of the combined process were better at room temperature. At a HRT of above 12h, TN average effluent concentrations were below 20mg/L, which were qualified to Standard B of "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant". At a HRT of 18h,12h, it was qualified to Standard A; NH3—N average effluent concentrations were below 25mg/L, which were qualified to StandardⅡof "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant". At a HRT of above 12h, it was qualified to Standard B; TP average effluent concentrations were below 1.0mg/L, which were qualified to Standard B of "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant".At a HRT of above below 12h, TN and NH3—N average effluent concentrations were above 25mg/L, they can not meet emission standards; TP average effluent concentrations was 1.0～3.0mg/L, which was qualified to StandardⅡ.In the system, for the remove of COD, role of ABR is larger, accounting for more than 60%, for the remove of NH3-N, TN, TP, vertical subsurface flow constructed wetland makes larger contribution.Regarding pollutant removal effect and stability of the combined process, the best HRT was 12h.
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