Combined Process of Multi-surface Flow Constructed Wetland and Oxidation Pond for Treatment of Micro-polluted Raw Water

The combined process of multi-surface flow constructed wetland and oxidation pond was used to treat micro-polluted raw water from fish pond aquaculture and agricultural production,and the pollutant removal effect of the constructed wetland was investigated.The results show that the treatment effect of micro-polluted raw water by wetland system is very significant.In the whole monitoring period,the average removal rates of COD,TN,NO-3-N,NO-2-N,TP and soluble TP are 53.7%,45.0%,34.0%,54.5%,48.7% and 50.5% respectively.The quality of the final effluent meets the standard of water environmental function area.As temperature is increased,the removal rates of COD,TN and TP are increased.In particular,their removal rates are increased sharply at 30.2 ℃ to 31.4 ℃.For the constructed wetland,there is a poor correlation between TN load and removal rate(R2=0.617 4),but there is a good correlation between TP load and removal rate(R2=0.913 0).Because of less investment,good effect,simple operation and management,the surface flow constructed wetland system has a good application prospect in reduction of pollution load into the lake.