Abstract:

In order totreat agricultural runoff pollution and mitigate river pollution , Horizontal flow constructed wetland system was used to treat agricultural runoff in this study. Treatment results show that when the influent flux is 2.5m3/d, horizontal subsurface flow constructed wetland has better purification effect, the removal efficiency of chemical oxygen demand(CODcr),total nitrogen(TN), ammonium nitrogen(NH4+-N) and total phosphorus (TP) in the horizontal subsurface flow constructed wetland were49.65%, 51.37%, 56.24% and 59.12%, respectively. Mean influent COD, TN, NH4+-Nand TP were GradeⅡ, Grade Ⅴ, GradeⅡand Grade Ⅳ, respectively. After the disposal of the constructed surface wetlands, Mean effluent COD and Mean NH4+-N can nearly reach GradeⅠ. Mean effluent TP can nearly reach GradeⅠ. Mean effluent TN can nearly reach GradeⅣ. From the analysis of the impact factors in the constructed wetland systems, it can be seen that a key factor was to control the influent flux, and proper influent flux can obtain the optimum treatment effect.