Study On The Treatment Of Rural Dispersed Domestic Sewage By Integrated Device

In recent years,with the increasing emphasis on ecological environmental protection throughout the country,more and more areas of ecological environmental protection works shift from urban to rural areas.The main environmental problem in rural areas is the direct discharge of domestic sewage,resulting in water pollution.The problem of water pollution not only affects the living conditions of rural residents,even surface water and groundwater are polluted.For rural decentralized sewage,the amount of water is small,the time and space changes greatly,and it is necessary to search for reasonable and appropriate treatment facilities to improve the ecological environment in rural areas.The treatment of decentralized sewage can not be copied from urban centralized sewage treatment.Whether it is construction or operation and maintenance,it is difficult for rural areas to bear such large human resources and material resources.There is an urgent need to design a small sewage treatment facility that is suitable for easy maintenance in rural areas.The focus of this study is to treat the rural decentralized domestic sewage by self-designed integrated biological contact oxidation-submerged constructed wetland.The design treatment water volume is 4m~3/d,and the experiment is carried out for one year,and the different operating parameters are changed to obtain different effect.The sewage treatment effect and the main factors affecting the treatment effect are obtained,and device is further optimized from the design to achieve the purpose of promotion.The device can be applied to rural areas such as multi-family joint use,farmhouse or small-scale natural villages.During the test,the main test process was used to remove COD,ammonia nitrogen and total phosphorus from sewage.The biological contact oxidation tank is started separately.By changing the influent load,the optimal operating parameter of the process is 4m~3/(m~2·d).Under low temperature conditions,the removal rates of COD and ammonia nitrogen?total phosphorus were 81.3%,75.5%,and 58.9%,respectively.By changing the aeration mode,continuous aeration and intermittent aeration(aeration time:stop exposure time=1h:1h,1h:2h,1h:3h)),determine the best working condition is the ratio of aeration time to stop exposure time is 1h:1h,the removal rate of COD,ammonia nitrogen and total phosphorus in biological contact oxidation pond is 83.9%,71.7%,60.9%.High temperature in summer,but the average COD concentration in sewage is 130mg/L,the average value of ammonia nitrogen is 10mg/L,and the average value of total phosphorus is 2mg/L.In the oxidation tank,the removal rate of COD,ammonia nitrogen and total phosphorus was 61%,58.9%and 56.3%respectively.By running the submerged constructed wetland separately,the influent is biochemical tail water,in which the average values of COD,ammonia nitrogen and total phosphorus are 70mg/L,10mg/L and 1.4mg/L respectively,the optimal hydraulic retention time in the wetland is HRT=2d,the removal rates of COD,ammonia nitrogen and total phosphorus are 56.4%,53.4%and 62.5%,respectively.The effluent can basically reach the level A emission standard.Through the operation of the device for a whole year,the combined process is more stable in the removal of pollutants,and the treatment effect is better,the average annual removal rate of COD is 86.2%,the average removal rate of ammonia nitrogen is 84.3%,and the annual average removal rate of total phosphorus is 81.6%.And at the same time,it is partially affected by the season.Overall,the treatment effect is stable,indicating that there is strong anti-shock load in the process.The microscopic examination of the biofilm was carried out by optical microscopy to qualitatively judge the operation effect of the biological contact pool.The observed protozoa and metazoan were abundant,indicating that the biological contact oxidation pond has strong treatment capacity and the effluent water quality is excellent.In addition,the phospholipid method and dehydrogenase activity were used to study the biomass and biological activity of the biofilm,indicating that where the concentration of the contaminant is high,the biomass is high and the activity is high and the surface biomass and activity are slightly lower than the bottom.The strength of nitrification in the matrix was positively correlated with the removal of ammonia nitrogen.The activity of nitrification bacteria in wetland was studied by studying the intensity of nitrification in wetland matrices.The results showed that the strength of nitrification in the surface and bottom decreased along the flow.But at 30 cm depth,the strength of matrix nitrification shows different rules,in which the middle is larger than the two ends.