Study On Rural Domestic Sewage Treatment Technology And Facilities Operation And Management Mode In Tuhai River And Majia River Basin

In recent years,rural sewage discharge of Tuhai River and Majehe River Basin increased year by year.In the absence of the necessary sewerage and treatment facilities,the phenomenon of domestic sewage discharge at random was serious,the water environment of Tuhai River and Majiahe River Basin was deteriorated,and the shortage of water resources became more prominent,which not only threatened the safety of drinking water quality of the villagers in the river basin,but also affected the healthy and sustainable development of the social economy in the basin.The effect of sewage treatment in rural areas was mainly depended on the choice of treatment technology and the operation and management of treatment facilities.On the one hand,with the greater advantages in technical,financial and management,capillary sewage purification system had been widely used in foreign countries of the decentralized sewage treatment,and it also had a broad application prospect in the northern rural area of our country.However,the choice of fillers and the selection of operating conditions of current capillary water purification system was not scientific and rational enough,which resulted the treatment effect was not ideal.Therefore,it was of great practical significance to study the removal effects of different packing combinations and operating conditions of pollutants and propose the scheme of system structure improvement and operation process optimization.On the other hand,there were serious problems in the operational management level of rural domestic sewage treatment facilities in the laws and regulations,capital investment,supervision and other aspects,which resulted in inefficient operation of treatment facilities inTuhai River and Majia River Basin.Therefore,on the basis of the study on sewage treatment technology,it was particularly importantt to pay attention to the operation and management modes of sewage treatment facilities and optimize the management models which were suitable for rural economy bearing capacity and had good treatment effect.At the technical level,the capillary sewage purification system was used in this study,the effects on COD,NH4+-N of two mixed loading ratios of zeolite,activatedcarbon and anthracite adsorption were studied.Based on this,the removal effects of COD and NH4+-N under different hydraulic loading and different concentration stages were studied.The main conclusions were as follows:(1)The mixed loading way of zeolite,activated carbon and anthracite was selected,and the proportion was 3: 1: 1,1: 1: 1.Under the condition of 0.4m3/(m2?d)of hydraulic loading and 36 hours of hydraulic retention time,the highest removal rates of COD of two proportions were above 62%,the highest removal rates of NH4+-N of two proportions were above 77%.The ratio of 3: 1: 1 of the removal effect on COD and NH4+-N was better than the ratio of 1:1:1;the removal effects of two proportions NH4+-N were better than COD;the optimum hydraulic retention time was 12 hours.(2)Under the conditions that the mixed filling ratio of zeolite,activated carbon and anthracite was3:1:1,the hydraulic retention time was 12 hours,the effect of hydraulic loading on COD and NH4+-N was 0.1m3/(m2?d)>0.3m3/(m2?d)>0.5m3/(m2?d),and the hydraulic loading of 0.3m3/(m2?d)was more applicable.(3)Under the conditions that the mixed filling ratio of zeolite,activated carbon and anthracite was3: 1: 1,the hydraulic loading was 0.3m3/(m2?d),the hydraulic retention time was 12 hours,the removal effects of COD in the three concentration stages of 54~152 mg/L,204 ~ 296 mg/L,356 ~ 447 mg / L and the removal effects of NH4 +-N in the three concentration stages of 6 ~ 14 mg / L,21 ~ 32 mg / L,38 ~ 60 mg / L were compared.The results showed that the removal efficiency of COD and NH4+-N was the best in the lowest concentration.Therefore,in the actual project,it was recommended that pretreatment of domestic sewage should be carried out and the concentration of waste water should be reduced before using capillary sewage purification system.At the operation and management level of domestic sewage treatment facilities,The status quo and main problems of the operation and management of domestic sewage treatment facilities in Tuhai River and Majia River Basin was analyzed the management experiences of rural sewage treatment facilities in the United States,Japan and South Korea and the main management modes of rural domestic sewage treatment facilities in China were introduced.According to the selection principle ofoperation and management mode of sewage treatment facilities,three types of operation and management modes that the level was gradually improved were suggested,which were villagers' autonomous management mode,entrusted operation mode,BOT mode.And the safeguards were proposed from the aspects of market environment,laws and regulations,capital security,regulatory mechanisms,environmental awareness.The three management modes were suitable for the following areas:(1)In areas of Tuhai River and Majiahe River Basin where were far away from the cities,the villages were scattered,the economic level was low,the biochemical property of water quality was good or the effluent requirements were low,and the scattered sewage treatment facilities were used,the villagers self-management mode to manage sewage treatment facilities was recommended.(2)In suburban rural areas where were close to cities,densely populated,well developed,demanding drainage,and access to environmental service providers;or close to the river,where the environment was more sensitive to rural areas,such as the coastal villagesof Tuhai River,Majia River,Dehuixin River,the commissioned operational mode to manage sewage treatment facilities was recommended.(3)In the township or new rural residents community where residential concentrated,the water discharge was large,the treatment technologies were complex,the drainage requirements were higher,the economy was more developed,the environmental service providers were easy to seek,the water reuse was required,the permanent establishment of sewage treatment facilities was required,the BOT mode to manage sewage treatment facilities was recommended.