Experimental Study On Rural Domestic Sewage Treatment By Three-stage AO Contact Oxidation Process

With the development of rural areas,the demand for living standards is also rising.However,in most rural areas,the infrastructure is still not perfect,garbage and sewage dump lead to poor overall rural appearance,especially in the sewage area,which breeds many problems.Based on the current situation of rural sewage treatment,according to the characteristics of rural domestic sewage,compared with the advantages and disadvantages of sewage treatment methods,the most suitable contact oxidation process is selected.This study has guiding significance for rural sewage treatment,in line with the current trend of new rural development and construction,can provide theoretical basis for rural sewage treatment,and find a way for rural sewage treatment.The research mainly uses three-stage AO contact oxidation process,and from the perspective of energy saving and consumption reduction,adopts the way of natural water drop to supplement dissolved oxygen.First of all,the drop effect of the test device is debugged,and the appropriate height and baffle type are discussed.Considering the method and influencing factors of film hanging,the film hanging was studied.After the film hanging,the influencing factors of the process were studied.A single variable test was carried out to determine the best value of each variable.Finally,according to the relationship between the treatment effects of different stages in multi-stage process,several groups of combined parameters are deduced and their treatment effects are studied.In the whole research process,three pollution indexes,COD,ammonia nitrogen and total phosphorus,are mainly detected.The effluent is required to reach level a standard,that is,the effluent of COD is less than 50mg/1,the effluent of ammonia nitrogen is less than 15mg/1,and the effluent of total phosphorus is less than 1mg/1.In the debugging research of water drop effect,we mainly focus on two better control variables;the height of water drop and the baffle.Six sets of variable values are set in the range of 0.2m to 0.8m.According to the change of dissolved oxygen before and after the water drop of different heights,the water drop height of the device is finally determined to be 0.5m.According to the difference of joint width and shape,there are four types of water drop baffle.According to the increment of dissolved oxygen after water drop,the rectangular baffle with the vertical joint spacing of 4cm and joint width of 3mm is finally adopted.Hanging film is the most basic and important part of the whole research.The method of natural film hanging is adopted.Although it takes a long time,the hanging film is stable and the effect is good.In consideration of the influence factors of membrane hanging,maintain the temperature at 20?25?,control the aeration intensity properly,and respectively introduce the same sewage into all levels of reactors.The pollutant concentration of the sewage gradually increases.In this process,observe the change of the filler surface,compare the occurrence of the biological phase,and detect the content of COD in the effluent.Finally,after a month and a half,it was found that the surface of the filler had obvious adhesion layer,and the thickness was not changed any more.The COD of effluent at all levels reached about 32.6mg/l,and the film hanging was basically completed.In the study of process influencing factors,three variables,hydraulic retention time,auxiliary aeration and pollution load,are discussed.The method of controlling single variable is adopted.Several different parameter values are set for each variable to keep other conditions unchanged.One variable is changed to detect the total effluent content of COD,ammonia nitrogen and TP and the effluent content at all levels.By analyzing the total effluent effect of pollutants,the optimal operation parameters are determined as the hydraulic retention time of 6h,auxiliary aeration of 400L/h,COD of 300mg/1,ammonia nitrogen of 30mg/1 and TP of 2mg/1.By analyzing the relationship between the removal efficiency of the reactors at all levels,it is found that the removal capacity of the reactors at all levels is basically the same within the controllable range of pollutant concentration.According to the relationship between the treatment effects at all levels,on the one hand,in order to maximize the energy efficiency of the reactor,on the other hand,in response to the different conditions of rural sewage quality,to provide new theoretical data for the areas where the pollution load can not reach the best parameters,the idea of combining and verifying the parameters is put forward.In this part,the removal efficiency of the reactor under four different parameter combinations was studied.The results show that the four parameter combinations can make the sewage discharge up to the standard.The research provides theoretical support for rural sewage treatment,and has very practical significance.The research has different operation modes in the actual process,and the applicability of the process is very strong.Different application modes bring different benefits.It is necessary to analyze the benefits for the application of the technology in practice.