改进型人工快渗系统处理村镇污水效能研究——水力负荷周期的影响

Study on treatment performance of rural wastewater using the improved constructed rapid infiltration system-The influence of hydraulic loading cycle

在传统人工快速渗滤(CRI)系统的基础上,构建非饱水层、饱水层两段式改进型CRI系统,并以玉米芯作为饱水层的固体碳源,探究了水力负荷周期(3,6和12h)对村镇生活污水处理效能的影响,分析了其微生物机理.结果表明,改进型CRI系统的最佳水力负荷周期为6h,系统出水化学需氧量(COD)、氨氮、总氮和总磷平均浓度分别为5.40,0.91,5.59与0.47mg/L,达到了《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A排放标准.微生物分析结果表明,系统COD的去除与硝化作用发生在系统的非饱水层,Proteobacteria和Actinobacteria是有机物代谢主要的功能微生物,Nitrospirae是主要的硝化功能菌.饱水层的功能微生物Chloroflexi降解玉米芯为反硝化过程提供了充足的碳源,并且携带高丰度的反硝化关键功能基因促进了饱水层的反硝化过程.研究结果不仅可以为农业废弃物的资源化利用实现村镇生活污水的提质增效提供依据,还可以为改进型CRI系统强化村镇生活污水的处理提供技术支撑.

Based on the conventional constructed rapid infiltration(CRI)system,the improved CRI system with non-saturated and saturated layers was constructed.The effects of three hydraulic loading cycles(3,6 and 12h)on the treatment performance of rural domestic wastewater were investigated when corn cob was added as solid carbon source in the saturated layer,and the microbial mechanism was further elucidated.The results showed that the optimal hydraulic loading cycle of the improved CRI system was 6h.Under the optimal hydraulic loading cycle,the average effluent concentrations of chemical oxygen demand(COD),ammonia nitrogen,total nitrogen and total phosphorus were 5.40,0.91,5.59 and 0.47mg/L,respectively.The effluent water quality index meets the“Discharge standard of pollutants for municipal wastewater treatment plant(GB 18918-2002)”level A standard.The results of microbiological analyses implied that the removal of COD mainly occurred in the non-saturated layer of the system,and the Proteobacteria and Actinobacteria were the main functional microorganisms involved in the metabolism of organics.Nitrification also occurred in the non-saturated layer,and Nitrospirae was the main nitrifier.Functional microorganism Chloroflexi in the saturated layer could degrade corn cobs and provide sufficient carbon source for denitrification process,and carry high abundance of key functional genes for denitrification at the same time,facilitating the denitrification process in the saturated layer.This study can not only provide a basis for the resource utilization of agricultural wastes,but also provide technical support for the improved CRI system to strengthen the treatment of rural domestic wastewater.