Comparative Study On Denitrification And Phosphorus Removal Characteristics Using Internal Carbon Source

Internal carbon source denitrification refers to the fact that some microorganisms such as denitrifying phosphorus accumulating bacteria and denitrifying glycogen accumulating organisms can consume PHB(poly-?-hydroxybutyrate)to provide energy for denitrification and provide energy for their growth and glycogen synthesis.Using internal carbon source to drive denitrification can simplify the denitrification process,save aeration,reduce sludge production,and solve the problem of lacking external carbon sources in the process of wastewater treatment.The effects of C/N ratio,carbon source type,electron receptor and internal and external carbon sources on denitrification and denitrifying phosphorus removal from denitrifying and denitrifying bacteria were investigated by using two sets of SBR reactors,respectively,in order to investigate the effects of C/N ratio,carbon source type,electron receptor and internal and external carbon sources on denitrification and denitrifying phosphorus removal.Carbon source conversion and denitrification of N2O in two microorganisms were studied.The results are as follows:Culturing microorganism with nitrate as electron acceptor and sodium acetate as carbon source.After 362 cycles of acclimation,denitrifying phosphorus accumulating bacteria were successfully cultured.The rate of phosphorus uptake by hypoxia reached 23mg/(L·h).After 320 cycles of acclimation,the removal rate of NO3--N of denitrifying glycogen accumulating organisms reached 31.3mg/(L·h).The influent C/N ratio has an important effect on the removal of nitrogen and phosphorus by DP AOs and DGAOs.When the influent COD concentration is 200-500mg/L and the anaerobic time is more than 1 h,the organic matter can be reduced to the minimum and the phosphorus release can be reached to the maximum amount at the same time.When the influent mass ratio of COD?NO3-N and soluble P is 300:90:15,the removal rates of PO43--P and NOx--N are 98.1%and 98.8%respectively.Nitrate of 1mg was consumed in anoxic stage with each absorption of lmg phosphate.In anoxic stage,the nitrate of 1mg is consumed per absorption of 1mg phosphate,and for the system of DGAOs,the best denitrification performance of denitrification is 89.1 when the mass ratio of COD to NO3-N is 400:60.When sodium acetate is used as carbon source,YWhen nitrite was used as electron acceptor,DP AOs and DGAOs were cultured.When nitrite was used as electron acceptor,the anoxic phosphorus uptake rate of DPAOs was 3.8 mg/(L·h),and the denitrification rate of DGAOs was 5.1mg/(L·h)when nitrate was used as electron acceptor,compared with 39.7 mg/(L·h)when nitrate was used as electron acceptor.The denitrification rate of the two microbes decreased 87%,but the denitrification rate of the two microorganisms decreased to 59.1%and 61.4 when the carbon source in the influent was glucose,respectively.The presence of external carbon sources in anoxic stage resulted in DP AOs.The effect of denitrification and phosphorus removal in the system becomes worse.The anoxic phosphorus uptake rate was only 7.7 mg/(L·h),which was 70%lower than that of internal carbon source,while DGAOs could use external carbon source for denitrification,and the degradation rate of NOx--N was increased by 4%compared with that of internal carbon source driven denitrification.The accumulation and consumption of PHB by the two microbes had a good correlation with the degradation of COD and the synthesis of glycogen.In anaerobic stage,PHB was consumed rapidly with phosphorus release and PHB accumulation.PHB in anoxic stage was degraded to provide energy for denitrification and glycogen was resynthesized.During a typical cycle,DP AOs and DGAOs produced about 0.63 mol?0.6 mol of glycoplasm per PHB consumed by lmol,respectively.The higher the C/N ratio of influent,the higher the storage rate and storage capacity of PHB in anaerobic stage,and the lower the synthesis rate of PHB and glycogen is when nitrite is used as electron receptor or glucose as carbon source.When the carbon source was added to the anoxic zone,the concentration of DGAOs and DP AOs were increased.Both of them produced N2O,which was 87%higher than that of the former.