Study On River Ecological Patch Construction And Water Purification Efficiency

Xiaoyi River is one of the major rivers in Baiyang Lake and an important ecological corridor of Xiongan new area.In view of the problems of the Xiaoyi River ecosystem being damaged and the water quality not reaching the standard all the year round,this paper takes Xiaoyi River as the main research object,aiming at reducing the pollution load and improving the self-purification ability of the river course,and taking into account the restoration of the river landscape,based on the characteristics of water environment in the Xiaoyi River,an ecological patch facility and a simulated river channel constructed on the basis of ecological patches were constructed to study the effects of hydraulic retention time and temperature on the purification of water quality in the ecological patches,the water purification efficiency of ecological patches under different pollution loads was analyzed,and the restoration technology of ecological patches was put forward based on the combination of composite fillers and emergent plants.The main results achieved were as follows:Pollutant reduction by ecological patches is influenced by hydraulic retention time.When the influent is of Class V（grade a discharge standard）and the HRT is 24h,12h and 6h,the removal efficiency of ecological patches decreases with the reduction of HRT.When the hydraulic retention time is 24h and12h,the effluent can reach the standard of surface type V water quality,and when the hydraulic retention time is shortened to 6h,the effluent can not reach the standard of surface type V water quality,the removal rates of TN,TP,NH₄⁺-N and COD were 28.8%,31.7%,40.7%and 25.3%respectively,which indicated that the ecological patch had better effect on the stagnant water with slow flow rate.Temperature has a significant effect on water purification efficiency of ecological patches.With the decrease of temperature,the removal efficiency of COD,NH₄⁺-N and TN by ecological patches decreased obviously,but the removal efficiency of TP did not change significantly.Under the condition that the influent is of low grade V（grade a discharge standard）and the surface of the river is of Grade IV,and the hydraulic retention time is 3 days,the simulated ecological patch river can remove COD,NH₄⁺-N,TN and TP effectively.The removal rates of TN,TP,NH₄⁺-N and COD in the simulated river reach 55.5%,41.3%,91.6%and 67.7%respectively when the influent is of low V quality under different pollution loads,when the inlet water quality is surface IV,the removal rates of TN,TP,NH₄⁺-N and COD in the simulated river reach 43.8%,58.3%,80.6%and 51.3%respectively,the effluent indexes can be further improved to meet the Grade III surface water quality standards,and the pollutant concentration gradually decreases with the flow of the river under the two pollution loads.The results show that the construction of ecological patches can effectively improve the water quality and enhance the self-purification ability of the river.Based on the results of field investigation and experiments,a set of ecological restoration scheme for Xiaoyi River,which integrates the construction of ecological patches,river slope regulation and river landscape restoration,is put forward,the objective is to improve the water quality of Xiaoyi River from Grade V to Grade IV of surface water.