Purification efficiencies of subsurface horizontal flow constructed wetland treating slightly polluted river water
潜流人工湿地对微污染河水的净化效果

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 CODMn 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 CODMn was poor for low CODMn 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.