曝气对潜流人工湿地污染物沿程降解规律的影响

通过构建曝气及未曝气潜流人工湿地小试实验系统,研究曝气对人工湿地床体中污染物沿程变化规律的影响。实验结果表明,曝气对污染物沿程降解规律的影响与污染物种类有关,在净化COD和氨氮时,曝气人工湿地污染物主要以水平推流式降解为主,未曝气系统床体中则出现分层现象,深度为40 cm以上的床体区域中污染物以水平推流式降解为主,40 cm以下区域则以垂直梯度降解方式为主。对于磷来说,两对比系统均以水平推流降解方式为主,但不同深度上的降解速率有所差异,曝气系统30~50 cm的床体中间层降解速率较快,而未曝气系统50 cm以下的床体底层降解速率较快。将对比系统总体净化效果进一步比较发现,对于COD的去除来说,温度的影响大些,而对于氨氮和TP的去除来说,曝气的影响则更为显著。

Effect of aeration on pollutant degradation through substrate of subsurface flow constructed wetlands

Two parallel pilot-scale subsurface flow constructed wetlands with and without aeration system were built to determine the effects of artificial aeration on pollutant transport and degradation through the substrate. The results indicated that the degradation rules influenced by the aeration were correlated with the contaminant types. For COD and NH₄⁺-N, horizontal plug flows were the major degradation forms in the substrate of the aeration constructed wetland, while two kinds of degradation forms appeared in the constructed wetland without aeration. The horizontal plug flow was almost the exclusive form in the top layer (above 40 cm), and vertical gradient degradation was the major form in the bottom layer (below 40 cm). Degradation rates were various in different depth of the substrate for TP in both of the two constructed wetlands. The degradation rate in the middle layer (30~50 cm) of the aeration systems was higher than that in the other layers, while it was significantly higher in the deeper layers (below 50 cm) than in the top layers for the constructed wetland without aeration. It was further noted from the comparison of pollutants removal capabilities between the parallel systems that temperature played a substantial role for COD removal, and aeration was more important for NH₄⁺-N and TP removals.