复合人工湿地处理低浓度畜禽养殖废水的净化效果

为了解人工湿地对低浓度畜禽养殖废水的去除速度与净化效果,采用4级复合人工湿地以间歇进水的方式处理低浓度猪场废水,监测不同时期各级湿地进出水中TN、TP、NH_4~+-N、COD_(Cr)等污染物指标浓度的变化。结果表明,复合人工湿地进水中TN、TP、NH_4~+-N、CODCr年平均初始浓度分别为41.6、8.4、21.4、253.9 mg·L~(-1),去除率分别为94.66%、79.36%、91.04%、32.32%。其中1级湿地(芦苇-砾石垂直渗透流)对TN、TP和CODCr去除速度较快,分别为2.9、0.6、7.5 g·m~(-2)·d~(-1);2级湿地(芦苇-沸石垂直渗透流)对NH_4~+-N去除速度较快,为1.8 g·m~(-2)·d~(-1);3级湿地(芦苇-砾石水平潜流)和4级湿地(稻田水平表面流)对污染物的去除速度较低,对TN、TP、NH_4~+-N的去除速度均小于0.4 g·m~(-2)·d~(-1),对COD_(Cr)的去除速度小于2.3 g·m~(-2)·d~(-1)。污染物去除率受季节温度变化的影响较小。

Purification performance of combined constructed wetlands on livestock wastewater with low concentration of pollutants

In order to evaluate the removal rate and efficiency of livestock wastewater with low concentration of pollutants in constructed wetlands,four-stage combined constructed wetlands were used to purify piggery wastewater with low concentration of pollutants under intermittent influent.The variations of TN,TP,NH₄⁺-N,and COD_Cr in different stages of the wetlands were monitored during spring,summer,autumn,and winter.The annual average concentrations of TN,TP,NH₄⁺-N,and COD_Cr in the influent were 41.6,8.4,21.4,and 253.9 mg·L^-1,respectively,and the removal efficiencies of these pollutants were 94.66%,79.36%,91.04%,and 32.32%,respectively.In addition,the first stage of the wetlands (reed-gravel vertical seepage flow) had higher rates for removing TN,TP,and COD_Cr,which were 2.9,0.6,and 7.5 g·m^-2·d^-1,respectively.The second stage of the wetlands (reed-zeolite vertical seepage flow) showed a high removal rate for NH₄⁺-N,which was 1.8 g·m^-2·d^-1.However,the removal rates of pollutants in the third stage (reed-gravel horizontal undercurrent) and the fourth stage (rice-soil surface flow) of the wetlands were lower.The removal rates of TN,TP,and NH₄⁺-N were all less than 0.4g·m^-2·d^-1,whereas that of COD_Cr was less than 2.3 g·m^-2·d^-1.Season and temperature had little influence on the removal rates of most of the studied pollutants.