Research On Process Optimization Of Aquatic Plants And Microorganisms Synergistic Remediation Technology In The Treatment Of Urban Black-odor River Water Bodies

The pollution of urban rivers has caused the occurrence of black and odorous water bodies,which has a serious impact on people’s life and health,so it has gradually become a problem that needs to be solved urgently.Based on the experimental study of a black and odorous river water restoration project in Shanghai,this paper studies the process optimization in the restoration and treatment of urban black and odorous river water based on the synergistic restoration technology of aquatic plants and microorganisms,so as to pass the small test research and apply it to practical projects.The results are as follows:1.By enriching and cultivating the dominant strains and experimenting on their growth rules,lactic acid bacteria began to enter the logarithmic growth phase after 8 h of culture,and began to enter the stable phase after 16 h,it can be found that the stable period is longer;ammonia-oxidizing bacteria began to enter the logarithmic growth phase at 45 h,and began to enter the stable phase after 60 h.Therefore,after expanding the culture of the strains in the follow-up test,the immobilization test of the polyurethane carrier was carried out in the stable period of the bacterial liquid.2.In the experimental study on the adsorption capacity of immobilized microbial carriers,the results showed that the polyurethane carrier quickly adsorbed the bacterial solution within35 h,and after 40 h,the adsorption trend reached a stable state and approached saturation.The adsorption capacity of YJ group was 3.5×106 cfu·g^-1 by dilution plate counting method.The adsorption capacity of RJ group was 3.2×106 cfu·g^-1.It shows that the polyurethane carrier has a good adsorption effect.3.The small-scale device test showed that under the optimal conditions of static remediation of black and odorous river water,the removal effect of COD in each section of the water body was significant,and the COD removal rates in the upstream,middle and downstream of the river reached 54.9%,45.6%and 35.9%,respectively.The concentration of COD in the lower reaches of the river with heavy pollution decreased to 27.9 mg·L^-1,which met the COD index concentration in the IV water standard of surface water（GB 3838-2002）.The removal rates of NH₃-N in each section were 73.1%,69.8%and 67.7%,respectively.The removal rates of TP in each section reached 61.90%,58.6%and 53.3%,and the average TP in the water decreased to 0.38 mg·L^-1.Under the condition of dynamic restoration of black and odorous river water body,the removal effect of COD in each section of water body is more significant than that of static treatment,which improves the hydrodynamic force,makes the water body flow,accelerates the metabolic degradation efficiency of the dominant bacteria in the water body to the polluted organic matter,and further increases the reoxygenation capacity of dissolved oxygen in each section of water body.The removal rates of COD in the upstream,middle and downstream of the river were 61.0%,58.2%and 49.4%,respectively.The average COD of water decreased to 20 mg·L^-1,and the removal rates of NH₃-N in each section also reached 75.5%,81.7%and 79.8%.The average NH₃-N decreased to 1.13 mg·L^-1.TP removal rates were 64.3%,67.8%and 69.9%,respectively.The average TP decreased to below 0.3mg·L^-1.In the small-scale test device,under the condition of static and dynamic remediation of black and odorous water bodies,each section of water body is not treated before remediation.The p H was in the normal range,so the p H fluctuation was between 7.4 and 8.0 in the small test device.4.The results of practical engineering application show that the average removal rate of chemical oxygen demand COD in each section of the river reaches 71.3%,the average removal rate of ammonia nitrogen NH₃-N reaches 84.1%,and the average removal rate of total phosphorus TP reaches 89.9%.The dissolved oxygen in the water was increased from 1.1mg·L^-1 to 4.5 mg·L^-1 before the restoration.After the restoration,the overall water quality of the river was improved from the original inferior V water body to the’surface water environmental quality standard’（GB 3838-2002）IV water standard,and the black and odorous situation of the river was completely eliminated.The middle aquatic plants planted on the river account for about 3.2%of the water surface area of Acorus calamus,4.8%of Iris pseudacorus,3.2%of Eichhornia crassipes and 1.6%of Vallisneria natans.At the same time,it plays a role in enriching the community structure of surrounding aquatic plants in the overall river ecological restoration system.The experimental study on the synergistic remediation technology of aquatic plants and microorganisms in the treatment of black and odorous river water bodies has achieved remarkable results.In order to optimize the artificial increase of aeration mode,accelerate the reoxygenation speed of black and odorous water bodies,and improve the hydrodynamic force,the optimization of the overall treatment process has greatly improved the restoration of water bodies and the removal of pollutants.A preliminary exploration has formed an optimized route for the restoration process of black and odorous river water bodies.At the same time,the optimized process can provide engineering reference for the treatment of urban black and odorous river water.