Study On Packing Performance And Antibiotic Removal Of Integrated Rural Sewage Treatment Equipment

Rural sewage discharge is large,but the treatment rate is low,the rural environment pollution is serious.At present,the treatment of rural sewage is mainly towards the direction of integrated equipment development,but the integrated sewage treatment equipment is still in the initial stage in China.There are a series of problems,such as the limited removal capacity of nitrogen,phosphorus and typical pollutants in sewage,and the treatment structures occupy a large area,small-scale equipment in the late operation is poor and so on.MBBR,combining the advantages of biofilm and activated sludge process,has the characteristics of strong impact resistance and high long-term operation stability,and has become the mainstream process of integrated rural sewage treatment.At present,most studies on suspended fillers in MBBR process focus on their water purification ability but ignore the relationship between the membrane hanging rate of fillers and the start-up time of MBBR process.In recent years,more and more antibiotic residues have been detected in the research of rural sewage.At present,the research on rural sewage mainly focuses on the removal mechanism of nitrogen and phosphorus,and little attention is paid to the removal mechanism of antibiotics in rural sewage.Therefore,the study of filler performance for MBBR integrated equipment to treat conventional pollutants in rural sewage at the same time,to achieve the removal of antibiotics has become a new focus.In this paper,the actual rural domestic sewage in A township of Fujian Province is taken as the treatment object,through the construction of"anoxic-aerobic MBBR-aerobic MBR(A-MBBR-MBR)"integration equipment.The experimental results show that the COD removal rate of A-MBBR-MBR integrated equipment is93.33%,the NH4~+-N removal rate is 90%,the maximum removal of TN can reach more than 70%,the equipment has A good removal effect on conventional pollutants.Different suspension fillers have different effects on wastewater treatment of integrated equipment.The biomass and growth rate of PPC biological fillers were higher than those of polyurethane floating-ball fillers,braided floating-ball fillers,polyurethane sponge fillers and polyethylene(PE)plastic suspension fillers.In the small-scale test,the removal effect of PPC biological fillers on COD and NH4~+-N is better than that of the other four fillers.When PE packing and PPC packing were added into two integrated equipment,PPC packing equipment had better removal effect on conventional pollutants in stable operation stage.The average removal rate of COD,NH4~+-N and TN of PPC packing equipment were 1.51%,12.22%and 8.63%higher than that of PE packing equipment.Taking the discharge water standard as the reference for the completion of equipment startup,the startup time of PPC packing equipment is 6days shorter than that of PE packing equipment.Through calculation,the sludge yield rate of PE packing equipment and PPC packing equipment is 0.15 kg MLSS/kg COD and 0.08 kg MLSS/kg COD respectively.PPC packing equipment has a lower sludge yield,which is more conducive to the long-term operation,maintenance,and management of the integrated equipment for rural sewage treatment.In the long-term operation process of PPC packed A-MBBR-MBR integrated equipment,the average removal rates of COD,NH4~+-N,TN and TP are 81.85%,92.63%,72.15%,22.04%,respectively,and the long-term stable removal of organic matter,NH4~+-N and TN is realized.Hypoxic-aerobic MBBR-aerobic MBR equipment has a certain effect on the removal of all kinds of antibiotics.The removal efficiency of A-MBBR-MBR equipment for tetracycline and macrolide antibiotics was poor,with the removal rates of12.52%-21.89%and 20.07%-35.84%,respectively.The removal rates of sulfonamides and quinolones were 41.83%～60.00%and 38.53%～45.14%,respectively.Compared with the rural sewage treatment systems of different scales,the removal rates of the target antibiotics by A-MBBR-MBR,bio-rotating plate+constructed wetland,bio-rotating plate and A~2O/MBR were 14.22%～60.15%,-4.79%～54.19%,-1.4%～67.62%and-3.18%～53.92%respectively.The results showed that the A-MBBR-MBR integrated equipment had a good effect on the removal of antibiotics.Through the correlation analysis of the removal rate of conventional pollutants and the removal rate of various antibiotics in rural sewage treatment equipment of different scales,it was found that the A-MBBR-MBR integrated equipment achieved better removal effect of conventional pollutants and promoted the reduction of target antibiotics to A certain extent.Risk quotient(RQ)comprehensive evaluation system was established to evaluate the environmental impact of residual antibiotics in the effluent of rural sewage treatment equipment of different scales.The effluent of different equipment has certain ecological risk to the environment,and the antibiotic removal ability of rural sewage treatment equipment needs to be further improved.