Study On Performance Of Nitrogen Removal And Kinetics Of Simultaneous Nitrification And Denitrification Using SBR Process

Eutrophication can be easily produced when nutrient matrials containing nitrogen and phosphorus was discharged in the river.Therefore,it is a research hot-pot to study a new kind of nitrogen and phosphorus removal process.As a new biological nitrogen removal process,simultaneous nitrification and denitrification(SND)developed in recent years can achieve nitrification and denitrification with one biological reactor.It can simplify operation conditions of denitrification,strengthen biological nitrogen removal process and improve efficiency of biodenitrification.Denitrifying phosphorus removal process can reduce 50%of sludge production,save about 30%of aeration and 50%COD,etc.,DPB can use COD to synthesize PHB in anaerobic phase and utilize PHB to dephosphorize in anoxic phase.Therefore,uone-carbon double-use" can be achieved.In the study,the influence factors of SBR-SND was investigated in the simulated sewage using sequencing batch reactor.And the sedimentation and EPS of activated sludge were also analyzed at different temperatures and the kinetic model of SND was established.Furthermore,AZSBR was adopted to investigate the efficiency of denitrifying phosphorus removal in the simulated sewage.Main affecting factors were investigated in order to achieve quick start-up and stably operation in the A2SBR system.The effect of influent COD,C/P,the influent nitrate concentration in anoxic phase,mixed liquor suspended solids,sludge retention time and temperature on the efficiency of denitrifying phosphorus removal were also analyzed.The results showed that removal efficiency of COD,ammonia nitrogen and total nitrogen were 60%,38%and 34%when the temperature,the runtime,C/N,sludge age and pH were 5±2?,8h,8,20d and 8,respectively.The removal efficiency of COD,ammonia nitrogen and total nitrogen are 69%,77%and 52%when the temperature,operation time,C/N,sludge age and pH were 10±2??7h,8,15d and 8,respectively.Removal efficiency of COD,ammonia nitrogen and total nitrogen are 84%,86%and 70%when the temperature,operation time,C/N,sludge age and pH were 20±2?,7h,10,10d and 8,respectively.Removal efficiency of COD,ammonia nitrogen and total nitrogen were 91%,93%and 85%when the temperature,operation time,C/N,sludge age and pH were 30±2?,6h,10,10d and 8,respectively.Therefore,SND can be realized at different temperatures.SVI value increased from 145 to 162 when the SBR was operated for 30d at 30±2?,and meanwhile SVI value increased from 150 to 300 and a serious inlflation was taken place in the activated sludge system when the SBR was operated 30d at 5±2?.The changes of ORP were monitored to indicate indirectly the degradation of organic compounds and realized real time monitoring.A2SBR process could be successfully started up within 31 days by using a periodical"anaerobic,sedimentation and water discharge,anoxic,sedimentation and water discharge",respectively,when influent COD was 200mg·L-1,PO43--P was 4-6 mg.L-1,and NO3--N in anoxic phase increased gradually from 25 mg.L-1 to 55 mg.L-1,respectively.Removal efficieny of phosphate and nitrate were respectively higher than 99%and 94%,and a high-efficient denitrification and phosphorus removal could be achieved by using a periodical“anaerobic,anoxic and fast aeration,when A2SBR was operated at room temperature,influent pH was 6.5-8.0,influent COD was between 200mg.L-1 and 250mg.L-1,C/P was maintained at about 30,MLSS was between 2500 and 3500 mg.L-1,SRT was 20 days,and the influent nitrate concentration in anoxic phase was 35 mg.L-1,respectively.SBR process was used to treat low COD/NH4+-N sewage without additional carbon sources when C/N was 4-5.SND could occur,but its efficiency was lower than that of simulated sewage.The system could achieve high SND efficiency when COD/NH/-N was increased to 12 by adding organic carbon(CH3COONa was used as external carbon source).The results showed that COD removal was hardly influenced by improving COD/NH4+-N from 5 to 12 in the sewage,which could inhibit the accumulation of nitrite and nitrate,and improve removal efficiency of TN.Therefore,it was favorable to SND.Kinetics of SND was analyzed according to Monod equation.Reaction rate constant of the simulated sewage was KT=0.595 x 0.8045(T-20),and reaction rate constant of actual urban sewage was KT=0.595 ×0.7424(T-20).Kinetic equation was established as follows:(dM/dt)SND=7.0151-0.3647M/0.0109+M.