Study On Purification Of Micro-polluted River Ecological Pond-Constructed Wetland System

In recent years,more and more small and medium-sized rivers entering the lake reservoir have been polluted,resulting in serious water pollution.In this paper,aiming at the problem of water pollution in Baiyangdian river,a water purification system based on ecological tang-constructed wetland system was proposed.The effects of pollution load,hydraulic load,and temperature on pollutant removal in the combined process system were studied,and the parameters of the system were determined.Moreover,the conversion and removal of nitrogen in each unit of the system were investigated by ecological dynamics model,and the model parameters of each unit were determined.In addition,the conversion and removal paths of nitrogen-containing pollutants in each unit were predicted under optimal conditions,and the conversion and removal rates were obtained.According to the technological parameters of the combinatorial system,the scheme of ecological tank-constructed wetland combinatorial system was designed,which provided scientific basis for the theoretical research and engineering design of the combinatorial system.When the hydraulic load of ecological detention pond,subsurface constructed wetland,and ecologically stable pond is 0.17,0.17 and 0.1 m3/m2/d,the ecological tank-constructed wetland system achieved the best performance in purifying the slightly polluted river water at 20?.Among them,the average removal rates of effluent COD,TP,TN and NH4+-N reached 22.5%,77.5%,78.8%and 51.7%,indicating that it met the surface water ? class water standard.When hydraulic load of the detention pond,subsurface flow constructed wetland,and stable pond retention pond increased to 0.25,0.25,and 0.17 m3/m2/d,the concentration of COD,TP,TN and NH4+-N still met the surface water ? class water standard.With the increase of pollution load,the effluent concentrations of COD,TP,TN and NH4+-N in the system basically did not change.However,when the temperature down to 4-7?,the TN concentration of effluent was high,which more than the surface V class water standard.The COD,TP NH4+-N less affected by temperature and water concentration,and it met the surface water IV class.In addition,the retention pond was mainly used to purify water quality in the ecological pond-constructed wetland system.The TP,TN and NH4+-N was removed mainly through the absorption of plants.The average removal rate accounted for 65.4%,55.2%and 70.2%of the whole system.The application of ecological dynamics model in composite system had good simulation effect.Among them,the simulated anastomosis of NH4+-N and NO3--N in the detention pond was high,and the efficiency coefficient reached 94.16%and 82.18%,respectively.However,the efficiency coefficient of NO3--N in the subsurface constructed wetland wetlands was higher than that of NH4+-N(67.23%),reaching 87.22%.According to the established simulation parameters,the conversion and removal paths of NH4+-N and NO3--N in constructed wetland units of detention pond and subsurface flow in the optimal combination system were predicted-The predicted and measured values were in good agreement.The removals of NH4+-N and NO3--N in the detention ponds was mainly by plant absorption,with absorption rates of 6.061 and 2.348 N/m2/d,respectively.The subsurface flow wetland mainly removes NH4+-N and NO3--N through the nitrification and denitrification of microorganisms,and the nitrification and denitrification rates are 10.000 and 8.529 N/m2/d,respectively.Combined with algae Zha lake environment present situation and the water quality and water quantity of Fuhe River,the ecological pond water quality purification scheme-artificial wetland system was designed and compiled.The layout plan was given.And the structural schematic diagram and effect diagram of each unit in the combined system were given.Further,the construction cost of the project was analyzed economically.