回流对水平潜流人工湿地污染物分布及去除效果的影响

Effect of effluent recirculation on the treatment efficiency of horizontal subsurface flow constructed wetlands

探讨回流及不同回流方式对水平潜流人工湿地污染物分布及去除效果的影响。对无回流、回流至进水处、回流至湿地前半部分3种回流方式进行试验研究,并对2种回流比(1∶1和10∶1)条件下的水平潜流人工湿地污染物去除效果进行比较。结果表明:回流比为1∶1的条件下,无回流与有回流的人工湿地的NH4+-N、PO34--P的去除率分别约为10%和40%,采用不同回流方式的人工湿地之间没有显著性差异;对总有机碳(TOC)的去除,回流至湿地前半部分的湿地较无回流湿地(44%)的去除率提高约17%。回流比为10∶1的条件下,采用回流方式的人工湿地的NH4+-N、PO34--P、TOC的去除率分别较无回流湿地提高了约13%、50%和43%,但采用不同回流方式的人工湿地之间没有显著性差异。回流比从1∶1提高为10∶1后,采用回流的人工湿地对NH4+-N、PO34--P和TOC的去除率分别提高了约10%、30%和30%,且不同回流方式之间并无显著性差异。

Effluent recirculation is widely used in the vertical flow constructed wetlands because of its advantage in nitrogen removal.However,the effect of recirculation in horizontal subsurface-flow constructed wetlands was insufficiently investigated.In this study,three sets of horizontal subsurface flow wetland systems including no recirculation（CW-1）,recirculation with effluent to inlet（CW-2） and recirculation with effluent distributed on the first half part of the bed（CW-3）,were built to investigate the performance of the wetlands under different recirculation types and ratios（1∶1 and 10∶1）.The results show that,when the recirculation ratio of 1∶1,the removal rates of NH＋4-N and PO3-4-P in the wetlands with or without recirculation were 10% and 40%,respectively,and there was no significant difference in the wetlands with different recirculation types.The removal of TOC in CW-3 was 17% higher than that of CW-1;under the recirculation ratio of 10∶1,the removal rates of NH＋4-N,PO3-4-P and TOC in the constructed wetlands with recirculation were higher than that of the constructed wetlands with no recirculation by 13%,50% and 43%,respectively,and there was no significant difference between different types of recirculation;After the recirculation ratio was increased from 1∶1 to 10∶1,the removal rates of NH＋4-N,PO3-4-P and TOC in the constructed wetlands with recirculation were higher than that under the condition of 1∶1 recirculation for 10%,30% and 30%,respectively,and there was no significant difference between different recirculation types.