潜流人工湿地对微污染河水的净化效果

为了探讨潜流人工湿地对微污染河水的净化效果,在野外条件下构建潜流人工湿地,分析了湿地中pH、氧化还原电位(ORP)和DO的进出水变化,考察了湿地中污染物的净化效果,探讨了温度对湿地净化效果的影响。各湿地进、出水DO浓度相差不大;除美人蕉湿地外,其余湿地出水pH较进水变化较小;植物湿地出水ORP较进水均有所增大。植物湿地对污染物的去除效果均优于空白湿地,且随着气温的升高,NH4+-N、TN和CODMn的去除率逐渐增加,去除率分别可达90%、50%和20%。TP去除率却未随温度发生明显变化,始终波动在30%～60%之间。相关性分析结果表明湿地中NH4+-N和TN的去除率与温度相关,较低的有机物浓度造成CODMn的去除率与温度相关性差,由于湿地对磷的去除主要以颗粒态磷(PP)为主,TP的去除与温度不相关。

Purification efficiencies of subsurface horizontal flow constructed wetland treating slightly polluted river water

Five identical subsurface horizontal flow constructed wetlands (SHFCWs) with different plants were constructed to treat slightly polluted river water under field conditions. The changes of pH, DO and ORP between influent and effluent were monitored, and also the impact of temperature on purification efficiencies was studied. Results showed that there were almost no differences between influent and effluent to DO in all five SHFCWs. Except wetland planted with Canna indica, there was a similar situation to pH in the rest of four wetlands. Compared with ORP of influent, ORP of effluent increased in planted wetlands. Removal rates of pollutants in planted wetland were higher than that of blank wetland, and the removal efficiencies of NH₄⁺-N, TN and COD_Mn increased with temperature increasing, which could reach to 90%, 50% and 20%, respectively. But removal efficiency of TP had no obvious change, varied from 30% to 60% in planted wetlands. The results of correlation analyses showed that there were significant correlations between temperature and removal of NH₄⁺-N and TN. The correlation between temperature and removal of COD_Mn was poor for low COD_Mn in influent. Because particulate phosphorus (PP) was the main form in all sorts of phosphorus removal, there was almost no correlation between removal of TP and temperature.