不同基质组合及水力停留时间下垂直流人工湿地的除污效果

Research on Pollutants Removal Effect of Different Combined Substrate under Different Hydraulic Retention Time in Vertical Flow Constructed Wetlands

对人工湿地基质进行合理组配并选取最佳水力停留时间可以有效地提高人工湿地污水处理效果并减少运行成本。选取火山石、粗炉渣、牡蛎壳3种基质,通过垂直流人工湿地模拟试验考察5种体积比的基质组合(分层装填1∶1∶1、2∶1∶1、1∶2∶1、1∶1∶2,混合装填1∶1∶1;分别编号为A、B、C、D、E)在不同水力停留时间(2、4、6、8、10 h)下的除污效果。结果表明:基质组合的装填方式对系统净污效果的影响极显著,分层装填的基质组合A的净污效果显著优于混合装填的基质组合E;不同体积配比的基质组合A、B、C、D对COD、NH_4^+-N的去除效果差异不显著,对TN、TP的去除效果存在差异显著;不同水力停留时间的净污效果也存在显著性差异,在一定范围内水力停留时间的延长可有效提高污水净化效果。此外,COD、TN、TP的去除率随着水力停留时间的增加有显著提高但到达最大值后有所下降;对NH_4^+-N而言,不同基质组合受水力停留时间的影响较大,无统一的最佳停留时间。基质组合和水力停留时间之间的交互作用对污染物的去除率影响并不显著,因此找出基质组合及水力停留时间的各自最优条件对于实际工程中的湿地除污效果具有重要的意义。

Collocating different substrate and chooseing a suitable hydraulic retention time could enhance the effects of pollutantsremoval effect of constructed wetlands. In our study, three kinds of the substrate, volcanic stone, coarse slag and oyster shell wereselected. and used to The pollutants removal rate under five kinds of combined substrate （grading loading of the combinedsubstrate 1∶1∶1, 2∶1∶1, 1∶2∶1, 1∶1∶2 and homogenous mixing of combined substrate： 1∶1∶1 individually） and fivedifferent hydraulic retention time （2, 4, 6, 8, 10 h individually） were measured using substrate column adsorption test. The resultsshowed that the pollutant removal efficiencies of COD, TN, NH4＋-N and TP were significantly different among different volumecombinations, with the better pollutant removal efficiency under grading loading of the combined substrate 1∶1∶1. The pollutantremoval efficiencies under different hydraulic retention time were also significantly different. With the extension of hydraulicretention time, the decontamination effect of four volume combinations was higher. No significant interactions were foundbetween volume combinations and hydraulic retention time. Our results highlighted the importance of collocate different substrateor choose a suitable hydraulic retention time in the decontamination effect of wetlands.