Study On Bio-Enhancement Technology Of Rural Wastewater By Co-Fermentation Of Excess Sludge And Secondary Effluent

Rural domestic sewage discharge fluctuates greatly,and the problem of cut-off occurs frequently.This study is committed to constructing an integrated rural sewage treatment system that combines residual sludge and secondary effluent co-fermentation.The feature of this system is that the mixture of secondary effluent and sludge fermentation broth is recharged during the cut-off period,which realizes the self-sufficiency of the biological treatment substrate and the efficient and stable removal of pollutants under the cut-off condition,which is the actual treatment of rural sewage Provides ideas.The main research results of this article are as follows:（1）Aiming at the current situation of frequent dry-off of rural sewage,through the screening of the biological system in the traditional A²/O process operating under dry-flow conditions,we have explored the 4 h,8 h,12 h and 16 h dry-off conditions.Under working conditions,the performance of nitrogen and phosphorus removal in the system and the changes in sludge indicators were tested,and the EPS,nitrification rate,denitrification rate,and phosphorus release and phosphorus absorption rate were tested.It was found that insufficient carbon source caused by flow interruption would inhibit the removal efficiency of pollutants,and the degree of influence is positively correlated with the increase of the cut-off time:the 4 h cut-off condition has little effect on the system,but after 8 h of cut-off,it will have varying degrees of impact on the system,and the cut-off reaches 16 After h,the system is difficult to maintain rapid collapse.The effluent COD,NH₄⁺-N,and TN of the system cannot meet the level A limit standard,and the effluent TP cannot meet the level B limit standard;the microbial population structure is also significantly affected,and the number of effective sequences And the diversity index gradually decreased,and the relative abundance of the phylum level and the genus level decreased.（2）In order to solve the problem of insufficient system matrix caused by cut-off,in line with the principle of resource recovery,anaerobic fermentation was carried out to produce acid by surplus sludge as the matrix to supplement the matrix and nutrient requirements during cut-off operation.The secondary effluent and the sludge fermentation broth are mixed at a ratio of 12:1 and have good biochemical characteristics,which can be used as a supplementary carbon source to flow back to the biological system under cut-off conditions to enhance the treatment efficiency of the A²/O system.The key factor of sludge fermentation is pH value.The acid production reaches its peak when the pH is about 10.The total acid production and the concentration of acetic acid are 180.51mg/L and 75.34 mg/L,respectively.（3）By simulating the water inlet conditions of 12 h and 16 h of cut-off,the effect of supplementary fermentation broth on pollutant removal performance and microbial population structure was systematically studied.The results show that under this new model,the effluent COD,NH₄⁺-N and TN of the system meet the first-level A limit standard,and the effluent TP meets the first-level B limit standard.The sludge performance is good,and the microbial population structure is effectively improved.The effective sequence number,diversity index,phylum level,and genus level abundance of sine were significantly improved compared with the 12 h and 16 h cut-off conditions.