水力负荷及固相碳源对BAF+多级土壤渗滤组合工艺处理污水的影响研究

碳源的选择及曝气量的控制是影响多级土壤渗滤系统(multi-soil-laying,即MSL)脱氮效果的重要因素.试验采用BAF+MSL两段式新型组合工艺,避免了传统MSL曝气过量抑制反硝化脱氮的风险.考察了不同水力负荷下,BAF+MSL对生活污水的净化效果,并比较研究了以聚丁二酸丁二醇酯(PBS)为反硝化碳源的MSL-1及木屑为碳源的MSL-2的脱氮除磷效果.结果表明,不同水力负荷下,系统对SS平均去除率为94.08%,对COD的去除率均在80%以上,出水COD在20mg·L-1以下.水力负荷对系统BAF段硝化性能影响较小,对MSL反硝化脱氮影响较大.BAF水力负荷为0.5、1及2m·3m-·2d-1时,BAF对NH4+-N的去除率均在90%以上,对TN的平均去除率依次为26.53%、11.09%、5.71%;对应MSL段水力负荷分别为0.25、0.50及1m·3m-·2d-1时,MSL-1对TN平均去除率分别为87.39%、65.09%、45.56%,MSL-2平均去除率依次为61.51%、42.52%、31.32%.MSL-1脱氮性能明显优于MSL-2,而两者除磷效果区别较小.随着水力负荷增大,MSL对TP去除率依次降低,MSL-1对TP平均去除率最高为91.97%.

Effect of hydraulic loading and solid carbon source on domestic wastewater treatment efficiency with BAF and multi-soil-layering combined process

Carbon source and aeration rate are the important factors affecting the removal efficiency of Multi-soil-layering (MSL) system. A new two-stage combined process of BAF+MSL was designed for purifying domestic wastewater under different hydraulic loading rate (HLR). Poly (butylene succinate) (PBS) and sawdust were used as carbon source in MSL-1 and MSL-2, respectively. Comparative studies on performance of nitrogen and phosphorus removal between MSL-1 and MSL-2 were also investigated. The result showed that the average removal efficiency of SS and COD were 94.08% and 80%, respectively, and the COD concentration in the effluent was below 20 mg·L^-1. The influence of HLR on denitrification of MSL was more significant than that on nitrification of BAF. When the HLR of BAF were 0.5, 1 and 2 m³·m^-2·d^-1 respectively, the removal efficiency of NH₄⁺-N was above 90%, and the TN removal efficiency were 26.53%, 11.09% and 5.71%, respectively. The corresponding HLR of MSL were 0.25, 0.5 and 1 m³·m^-2·d^-1, the TN removal efficiency of MSL-1 were 87.39%, 65.09% and 45.56%, respectively. In comparison, the removal efficiency of MSL-2 were 61.51%, 42.52% and 31.32%, respectively. Although the TN removal efficiency of MSL-1 was better than that of MSL-2, the TP removal efficiency of MSL-1 was similar to MSL-2. As the HLR increased, the TP removal efficiency reduced. The highest average TP removal efficiency of MSL-1 was 91.97%.