Study On The Method And Efficacy Of Hydraulic In-situ Bioremediation Of Wetland Water Environment

the problem of wetland water environmental pollution has become increasingly prominent.Wetland has a variety of important ecological functions and significant social and economic value.With the rapid development of urbanization and industrialization,the problem of wetland water environmental pollution has become increasingly prominent,it is urgent to control and restore the water ecological environment of polluted wetland.Longfeng wetland in daqing city is the largest urban wetland in China.Due to the influence of resource development,human life and agricultural production in Daqing City,the water ecological environment pollution is becoming more and more serious,it is urgent to improve and repair the ecological water environment of longfeng wetland.Based on the current water environment restoration methods and the mechanism of airlift reactor,this study developed an effective method for in-situ synchronous restoration of sediment and water pollution in longfeng wetland with hydraulic drive.The inner energy field and the diffusion distribution of each phase were explored by CFD simulation.By simulating the method of hydro-in-situ bioremediation with a small reaction device,the optimal remediation conditions were determined according to the degradation effects of various pollution indexes of water and sediment.The degradation efficiency of this technology for water and sediment pollution indexes was studied by comparing the conventional aeration method with the reactor test.The results show that:the torque of the impeller in the flow field is related to the velocity and density of the fluid,the inner and outer diameter and height of the impeller,and the basic parameters（installation angle,density,relative thickness）of the blade airfoil;Generally speaking,when the fluid flows through the axial-flow impeller,the pressure decreases from bottom to top,and the speed increases first and then decreases.The impeller rotation has an impact on the local pressure field and velocity field..At the inlet of the impeller,the pressure increases slightly from the outside to the inside of the impeller,and reaches the maximum value at the axis.At this time,the velocity is the minimum.In the middle and outlet of the impeller,the pressure gradually decreases from the outer wall to the edge of the impeller,and reaches the minimum at the outlet axis.The fluid velocity is maximum in the middle of impeller.The velocity of flow field in the hydraulic in situ bioremediation system is the highest at the inlet of gas velocity.The pressure decreases and the velocity increases when it enters the rising area.At the liquid surface,bubbles break up,and a small number of bubbles continue to flow with the fluid entering the falling zone.The mixing effect of axial-flow impeller and agitator will affect the streamline of flow field and make the flow spiral.The bottom of the reactor is mainly composed of mud phase;the middle part of the reactor is dominated by water phase,and the gas phase content gradually increases with the increase of upstream height.Orthogonal optimization test was carried out on the water environment restoration conditions,and it was concluded that aeration and stirring time are the main influencing factors of water body COD,TP degradation efficiency,sediment thickness reduction and sediment G value growth rate,affecting water body NH3-N The main factor of TN degradation rate is aeration intensity,and the main factor that affects the rate of sludge organic matter reduction is the stirring position.Hydraulic in-situ bioremediation can effectively improve the apparent index of water environment,degrade organic pollutants and nutrients,and enhance the self-healing ability of water environment restoration.After the experiment,the transparency of the water increased significantly,and the oxidation layer formed on the surface of the sediment,and the thickness of the sediment was reduced to 6.5 cm.The degradation of organic matter in sediment reached27.33%,and the COD degradation rate in water reached 80.9%.The degradation rate of NH₃-N,TN and TP in water reaches 76.0%,79.0%and 69.2%respectively,and the concentration of dissolved oxygen in water rises to about 4.26mg/L.The growth rate of G value of biodegradability of sediment microorganism reached 328.45%,and the self purification ability of water environment was significantly improved...