Study On Application Of Biological Nitrogen Removal Technology Of Hybrid Biofilm-activated Sludge Process And Its Mechanism

Moving bed biofilm reactor process had been widely used,under the interaction of activated sludge and suspended carrier,hybrid biofilm-activated sludge process can improve the capacity of resisting impact load effectively,to improve the effect of wastewater treatment and water quality.Therefore,explored the way and reaction mechanism of hybrid biofilm-activated sludge process for biological nitrogen removal,and analyzed the effect of biofilm activated sludge for nitrogen removal,to offer the support for hybrid biofilm-activated sludge process biological nitrogen removal processing technology.Analyzed the microbial diversity,the dominant bacteria and the proportion of nitrogen removal microorganisms in activated sludge and biofilm from the aspect of molecular biology,to reveal the mechanism of hybrid biofilm-activated sludge for biological nitrogen removal,In order to provided theoretical guidance of biological nitrogen removal efficiency and operation stability.The research results indicated:(1)Through the analysis on the operation status and water influent and effluent conditions of Tuandao wastewater treatment plant in Qingdao city from June 2015 to May 2016,the average annual amount of water was 73675m3/d,the organic loading was 0.75 kgCOD/(m3·d),the average sludge concentration was 4821mg/L.The average influent concentrations of COD,NH4+-N,TN,TP were 737mg/L,54.74mg/L,76.23mg/L,29.7mg/L,the average effluent concentrations of that were 27mg/L,1.21mg/L,8.59mg/L,2.25mg/L,the average removal rates of that were96.12%,97.24%,88.38%,95.42%.The system was stable and nitrogen removal efficiency was great.The anaerobic denitrification of activated sludge and simultaneous nitrification and denitrification of aerobic reaction were observed in this system.(2)The results of anaerobic denitrification of activated sludge indicated:(1)Influent water quality with low ammonia nitrogen loading and high organic loading was benefit the anaerobic nitrogen removal efficiency of activated sludge,ammonia nitrogen removal rate increased influenced the anaerobic nitrogen removal efficiency of activated sludge.With the ammonia nitrogen load of influent increasing,the removal rate of ammonia nitrogen increased.When the organic loading was 1.2kg/m3·d,the removal rate of ammonia nitrogen was 21.95%.When the ammonia nitrogen loading was 0.02kg/m3·d,the removal rate of ammonia nitrogen was 20.43%,with the ammonia nitrogen load of influent increasing,the removal rate of ammonia nitrogen decreased.(2)With the stirring intensity increasing,the removal rate of ammonia nitrogen was increased,when the stirring intensity was 250r/min,and the dissolved oxygen concentration reached 0.3mg/L,the removal rate of ammonia nitrogen was 19.74%.(3)The influence factors of SND in the hybrid biofilm-activated sludge biological nitrogen removal system indicated:(1)When the dissolved oxygen concentration was 2mg/L,the removal rate of ammonia nitrogen was 82.13%,the rate of SND was 56.8%,it reached great nitrogen removal efficiency,but the dissolved oxygen concentration over 2mg/L,it just improved the ammonia oxidation performance of system,almost no longer had significant influent to the rate of SND.(2)The removal rate of ammonia nitrogen was 76.98%,and the rate of SND was 47.16% when the condition of C/N was 3.When the condition of C/N was over 3,the organic load was higher,and the competition of microorganisms for dissolved oxygen more seriously,which affected the nitrification performance and reduced the removal rate of ammonia nitrogen.(3)With the increasing of MLSS,the rate of SND increased.When the MLSS reached 5g/L,the removal rate of ammonia nitrogen was 98.68%,the rate of SND was 76.98%,then with the MLSS increasing,the rate of SND and the removal rate of ammonia nitrogen were decreased.(4)Studied on the effect of the hybrid biofilm-activated sludge system on microbial structure by Miseq high-throughput sequencing:(1)The microbial community structure diversity of biofilm was higher than that of activated sludge,but the microbial community ecological dominancy of activated sludge was higher than that of biofilm.Activated sludge microbial structure was relatively concentrated,microbial community structure of biofilm was rich but not uniform.(2)When the water temperature was 15~20 ?,proportion of nitrogen removal bacteria in total bacteria was higher,it can ensure system have great nitrification performance.(3)The proportion of Nitrosomonas was higher in activated sludge and biofilm,and the presence of Haliscomenobacter in activated sludge and biofilm was the reason for activated sludge anaerobic nitrogen removal.(4)Compared with activated sludge,biofilm had a stronger ability to enrich nitrite oxidizing bacteria,especially Nitrospira.Therefore,the nitrification performance of activated sludge increased by adding suspended carrier.(5)The distribution of denitrifying bacteria in activated sludge was relatively uniform and the diversity was high,so activated sludge was mainly used for denitrification.And the existence of aerobic denitrifying bacteria like Comamonas,Enterobacter,Paracoccus,Pseudomonas and so on were also the reason for simultaneous nitrification and denitrification.