Research On Urban Sewage With High-ammonia Nitrogen By A/O/A SBR Process

Biological treatment methods of nitrogen and phosphorus removal became a research hotpot at home and abroad.In view of urban sewage with high ammonia nitrogen,low carbon nitrogen rate and other characteristics at the moment,traditional biological technologies could not meet the current emissions requirements,so the more efficient,more stable and more economic new biological nutrient removal process was urgently needed.Based on sequencing batch reactor,the experimental system coupled shortcut nitrification and denitrification with phosphorus removal process through anaerobic,aerobic,anoxic operation mode.By optimizing the reaction process and discussing influence factors,the suitable conditions of process operation was determined,and the mechanism of simultaneous nitrogen and phosphorus removal phenomenon was analyzed.The results were as follows:(1)The experimental sludge was cultivated and acclimated by optimizing inflow condition,limiting aeration and increasing inflow pH.During 46 days of two stages,the A/O/A SBR completed the startup,and the treatment effect of the experimental system was good.So it was feasible that only one tank SBR was used to remove nitrogen and phosphorus synchronously of urban sewage with high ammonia nitrogen and low carbon nitrogen rate.(2)Through continuous training and sample testing,treatment effects of the system under different C/N ratios,inflow pH values and aeration amounts were compared.And by analyzing the periodic changes of each pollutant,the suitable conditions of system operation was determined.When the consistence of COD,ammonia nitrogen,TN,TP of influent were 360~400mg/L,75~90mg/L,75~90mg/L,8.5~10.1mg/L with pH of 7.5~7.8 and aeration amounts of 0.08m~3/h,treatment effect of the experimental system was the best.And the consistence of COD,ammonia nitrogen,TN,TP of outfluent were 20~25mg/L,20~25mg/L,8~10mg/L,0.4~0.6mg/L,which was in line with the “First class A discharge standard”,while the average removal rate reached 95%?98%?89%?94% respectively.(3)With test apparatus and reaction conditions,the "nitrogen loss" phenomenonwas found during the aerobic phase,so was the synchronous removal phenomenon of nitrate nitrogen and phosphorus during the anoxic phase,which was discussed and researched through mechanism analysis and formula derivation respectively.It was showed that possible causes of the “nitrogen loss” phenomenon including simultaneous nitrification and denitrification(SND),assimilation of nitrogen,and ammonia stripping process,while the SND could be explained by macro mechanism,micro circumstance mechanism,intermediate formation mechanism or microbiology mechanism.Nitrate might have two ways to change into N2,and there was no constant proportion relationship between the synchronous removal of nitrate and phosphorus.