The Two-stage Anaerobic Digestion-Subsurface Flow Wetland Process For The Courtyard Sewage Treatment In South Hilly Aera

The rural courtyard sewage, which was composed of the courtyard sewage and the decentralized small-scale swine wastewater, was difficult for collection and centralized treatment and resulted in serious environmental pollution in the south hilly area. In order to resolve this problem, a typical farmer of this region was selected as the research object and the quality and quantity characteristics of the toilet flushing wastewater and source-seperation piggery flushing wastewater was investigated in this paper. Based on the pollutants source-separation technology, the two-stage anaerobic digestion subsurface flow wetland combined process was purposefully developed for the treatment of the toilet black water, the toilet black water and piggery flushing wastewater with different volumetric ratio, and the piggery flushing wastewater. For these wastewaters treatment, the efficiency and the operation parameters optimization of the combined process were also carried out in this study.The hydraulic retention time (HRT) and other conditions of the biogas digester simulation reactors were optimized for treatment of the toilet black water. The results showed that the optimum HRT of the biogas digester simulation reactor was72hours, and the efficiency and effect of the two-stage biogas digester simulation reactor was better than that of the one-stage reactor. When the HRT was72h, TCOD removal efficiency of the two-stage reactor could arrive67%. The effluent COD, NH4+-N, TN, TP and pH value could meet the vegetable irrigation limitation values of Standards for Irrigation Water Puality GB5084-2005after the two-stage anaerobic digestion-subsurface flow wetland combined process.The pig manure, pig urine and piggery flushing wastewater could be effectively separated using environmental friendly piggery house and liquid-liquid separation technology, i.e. the source separation technology, and the separated piggery flushing wastewater pollutant loading was greatly reduced by approximately80%. When the pig raising number was lower than50, the mixed toilet black water and piggery flushing wastewater with different volumetric ratio could be effectively treated by the two-stage anaerobic digestion-subsurface flow wetland process, and the effluent COD, NH4+-N, TN, TP and pH value all met the water irrigation limitation values of Standards for Irrigation Water Puality GB5084-2005. This combined process was suitable for rural courtyard mixed sewage treatment and easy for practical application in south hilly area.When the two-stage anaerobic digestion-subsurface flow wetland combined process was applied for the treatment of the piggery flushing wastewater, the effluent COD, NH4+-N, TN, TP and pH value indices could meet the according limitation values of Disharge standard of pollutants for livestock and poultry breeding GB18596-2001except NH4+-N, and the effluent COD, NH4+-N, TN, TP and pH value indices could meet the limitation value of Standards for Irrigation Water Puality GB5084-2005except COD. The effluent needed further treatment to meet the NH4+-N and COD limitation values of the standards.