多点进水潜流湿地的水力效率及氮浓度空间变化

Hydraulic efficiency and spatial variation of nitrogen concentration in subsurface flow constructed wetlands with different multi-inflows

通过脉冲示踪实验比较了3种多点进水方式和一般推流式的水力效率,通过脱氮实验获得不同水力效率下总氮和铵态氮浓度的空间分布,并对水力效率和脱氮效率进行了相关性分析。结果表明:4种布水方式中,阶梯进水方式的有效体积比和水力效率均最高,此时潜流湿地系统内部水流停留时间分散程度较低,水流混合流动程度较弱,更接近于推流;不同布水方式下总氮在潜流湿地中的空间分布差异比铵态氮明显,阶梯进水方式有利于湿地后段的反硝化脱氮作用;水力效率与总氮去除率存在极显著的相关性,而与铵态氮的去除相关性不显著。

Through tracer tests,the hydraulic efficiency of four kinds subsurface flow constructed wetlands with different inflow configurations（i.e.,common horizontal flow and 3 kinds of multi-inflow）was examined,with the spatial variation of total nitrogen（TN）and ammonium nitrogen（NH＋4-N）in the wetlands and the correlation between the hydraulic efficiency and the nitrogen removal efficiency studied.Among the four inflow configurations,step-inflow had the highest hydraulic efficiency,because it had a long mean resident time and low residence time distribution（RTD）,revealing that the flow pattern was much closer to a plug flow with weaker vertical mixture.Under the four inflow configurations,the TN and NH＋4-N showed stratified distribution,and TN varied obviously as a result of different inflow configurations.The step-inflow was in favor of the denitrification in the back end of the wetland bed.There were significant relationships between hydraulic efficiency and TN removal efficiency,while hydraulic efficiency did not affect the removal of NH＋4-N significantly.