| Rural sewage treatment in China now has the problem of pollution sources scattered everywhere,sewage is not easy to collect,and the proportion of treatment is low.In view of the above problems in rural sewage treatment,a set of improved AAO integrated rural sewage treatment equipment was designed and constructed,which was guided by the theory of denitrification and phosphorus removal.Compared with the traditional AAO process,anoxic anaerobic reflux was added to the process,and the anoxic anaerobic environment was provided to enrich the denitrifying phosphorus accumulating bacteria.In aerobic area,fiber combination filler is added to enhance its nitrification capacity.The whole equipment has the characteristics of small footprint,simple process and stable effluent quality in the same shell,which is suitable for decentralized domestic sewage treatment.The modified AAO process improves the efficiency of nitrogen and phosphorus removal.The integrated equipment is suitable for small-scale village sewage treatment.This transformation has a certain significance for the development of the research and development of rural sewage integrated equipment and the development of AAO technology.The equipment has a good market application prospect and social economic value.This subject takes the actual sewage of Shijing sewage treatment plant in Guangzhou as the treatment object.Through the study of HRT,working condition ratio and mixed liquid reflux ratio three factors,the effect of denitrification and phosphorus removal in the modified AAO process and the effect of various factors on the effect of nitrogen and phosphorus removal are studied.HRT,the ratio of working condition and reflux ratio of mixed liquid have certain effects on the removal of COD,ammonia nitrogen,total nitrogen and total phosphorus of the improved AAO integrated equipment.With the increase of HRT,the removal efficiency of COD and ammonia nitrogen is getting better and better,but tends to be stable.With the continuous extension of HRT,the removal rate of the total nitrogen and total phosphorus tends to increase first and then decrease.With the increase of the volume of the anoxic pool,the removal effect of COD presents a step by step trend,and because of the anoxic pool.In the case of the volume increase,the volume of the aerobic pool is relatively reduced in the case of the total volume,so the removal efficiency of ammonia nitrogen is gradually reduced,the removal effect of total nitrogen and total phosphorus first rises and then decreases,and the proper increase in the volume of the anoxic area is beneficial to the denitrification of the equipment,and the effect of the reflux ratio of the mixed liquid on the four water qualityindexes is the same.COD had almost no effect on ammonia nitrogen,but it had great influence on total nitrogen and total phosphorus.With the increase of reflux ratio,it will increase first and then decrease.The optimum working condition of the improved AAO integrated equipment is HRT 10 h,the aerobic mixture reflux ratio R1 is 200%,the anaerobic anoxic reflux ratio R2 is 150%,the sludge reflux ratio is 80%.Under this condition,the average effluent concentration of COD,ammonia nitrogen,total nitrogen and total phosphorus is 19.03 mg/L,2.77 mg/L,8.53 mg/L,0.47 mg/L,which can reach the urban sewage treatment.The pollutant discharge standard of factories(GB18918-2002)is A standard.By comparing the optimal operating conditions of the improved AAO integrated equipment with the nitrogen and phosphorus removal efficiency of the modified AAO integrated equipment,the packed AAO process is better than the non packed modified AAO integrated equipment in the COD,ammonia nitrogen,total nitrogen and total phosphorus removal,and the effluent quality COD,ammonia nitrogen,total nitrogen and total phosphorus are 16.64,1.74,and 7.75 and 0.42 mg/L,and the difference between the highest concentration of effluent and the lowest concentration of effluent is relatively small,and the stability of the system is enhanced. |
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