Experimental Study On Treatment Of Rural Domestic Sewage By Multistage Biological Contact Oxidation Process

With the rapid development of the rural economy,people’s living standards have been significantly improved,and more and more attention has been paid to the treatment of domestic sewage.However,the existing urban sewage treatment process is not suitable for use in rural areas where the total amount of sewage is small,scattered,and the economic conditions are poor,and the technology is lacking.Therefore,it is urgent to design a suitable domestic sewage treatment in rural areas,which has both effluent stability and energy consumption.A process that is low in operation and simple in operation management.According to the characteristics of rural domestic sewage,design aerobic-oxygen-multi-stage anaerobic-aerobic biological contact oxidation process,through the control of dissolved oxygen,hydraulic retention time,location and scale parameters,such as the water respectively under the condition of single point into the water and more water in addition to the effect of carbon,nitrogen,the Beijing local standards to achieve water pollutant discharge standard(DB11/307-2013)in the class A discharge standard.The denitrification process was confirmed from the microbiological point of view and the optimal chemical phosphorus removal agent was selected with economic benefit.The main research conclusions are as follows:(1)Dissolved oxygen and hydraulic residence time have significant effects on the removal efficiency of process pollutants.Under the condition of single point influent water,the optimal dissolved oxygen in the O1 stage and the dissolved oxygen in the O2 stage were 4mg/L and 3mg/L respectively,and the hydraulic retention time was 6.55h.The average removal rate of COD was 92.14%,the average removal rate of ammonia nitrogen was 95.49%,and the average removal rate of total nitrogen was 3 1.52%.(2)The influent position and proportion and the hydraulic residence time have higher removal effect on process pollutants.Under the condition of multi-point water inlet,the optimal water inlet position and proportion of the multi-stage biological contact oxidation process is the first stage of aerobic(O1):the first stage of anoxic(A1)=4:1,and the hydraulic retention time is 6.55h.The average removal rate of COD was 91.93%,the average removal rate of ammonia nitrogen was 97.10%,and the average removal rate of total nitrogen was 64.27%.(3)The denitrification and denitrification of nitrogen can be carried out in both aerobic and anoxic sections.Among the aerobic and anoxic segments,Proteobacteria and Bacteroidetes have the highest relative abundance,and both of them have relatively high denitrifying bacteria,such as Arcobacter,Flavobacterium,Phaeodactylibacter,and Denitratisoma.Both aerobic and anoxic segments can perform denitrification and denitrification.(4)PAC is suitable for phosphorus removal reaction as chemical phosphorus removal agent.When the total phosphorus in effluent reaches the standard,the unit pharmaceutical cost of PAC is the lowest at 0.22 yuan/m3,and the dosage is 140mg/L.Moreover,the addition of PAC has almost no influence on the pH of effluent,which is suitable for promotion and use.