Study On Purification Of Polluted River Water In Xianghe Section Of North Canal By Constructed Wetland In Estuary

Due to the shortage of ecological water,urban rivers in the Beijing-Tianj in-Hebei region generally have serious water pollution problems.Although the total pollution of these rivers is not as large as that of large rivers,the concentration of pollutants has reached a high level,giving the mainstream water bodies brought serious pollution.Aiming at this problem,this paper takes two tributaries of the Xianghe section of the north canal(Fenggangjian River and Xiaoyoufa Drainage Channel)as the research object.Firstly,the pollution characteristics of the two tributaries are analyzed,and the two tributaries are predicted according to the river water quality model.Then the optimal construction model of the artificial wetland in the estuary is explored by constructing a tributary estuarine artificial wetland simulation device.Finally,a targeted tributary estuarine artificial wetland construction plan is developed.The results show that the concentration of pollutants in the Fenggangjian River and Xiaoyoufa Drainage Channel has a steady decline along the path;the water quality of the Fenggangjian River and Xiaoyoufa Drainage Channel has gradually improved over time,but due to changes in water volume,The water quality of Fenggangjian River is unstable.Comparing the one-dimensional steady-state one-component water quality model and the Dobers-Camp steady-state model simulation prediction with the water quality data of 2018,the simulation error of pollutants is within 10%.Therefore,the water quality model can be used for water quality prediction of two tributaries,providing a basis for the design of the estuarine constructed wetland.The results show that the removal rate of pollutants in the estuarine artificial wetland simulation device can reach more than 80%,the removal rate of plaque to pollutants is 55?70%,and the removal rate of pollutants in corridors is 10?30%.The removal effect of the plaque is much larger than the removal effect of the corridor.The pollutant removal rate is 60?65%at low pollution load,70?75%at medium pollution load,82?87%at high pollution load,and the lower the pollution load is removed.The worse the effect is;when HRT=27 h,the removal rate of pollutants is 70?85%,when HRT=13.5 h,the removal rate of pollutants is 70?80%,and when HRT=9 h,the removal rate of pollutants is 58?63%,the longer the hydraulic retention time,the higher the removal efficiency;when the water level is 15 cm,the removal rate of pollutants is 48?63%,and when the water level is 30 cm,the removal rate of pollutants is 70?80%.When the water level is 45 cm,the removal rate of pollutants is 83?93%,and the removal rate increases with the increase of water level.Under the three plaque arrangements,the removal rate of pollutants in each plaque changed significantly.The closer the plaque is to the water inlet,the higher the removal rate of pollutants.The removal rate of the first plaque to the pollutants can be reached 20%.Through the investigation of the site,the technical scheme of the artificial wetland in the estuary was proposed,and the preliminary design of the structure and the drawing of the schematic were carried out.The area of the constructed wetland demonstration project is 7,200 m2,the effective depth of the constructed wetland is 1.5 m,and the hydraulic retention time is 1 d.The main body is composed of plaques and corridors,belonging to the combined artificial wetland.The packing is made of gravel,zeolite and bioceramics.The selected plants are native plants,mainly Hydrocotyle vulgaris,Acorus tatarinowii,Pontederia cordata L and Sagittaria trifolia var.inensis.It mainly purifies the water quality of the tributaries and reduces the pollution of the tributaries to the main stream.