Study On The Stable Operation Of A~2SBR Denitrifying Phosphorus Removal System And The Treatment Effect Of Microorganism Agent

Recently,nitrogen and phosphorus pollution has become the focus in the field of water pollution prevention and control.Denitrifying phosphorus and nitrogen removal technology settled the inherent conflict in the traditional process of phosphorus and nitrogen removal,and makes the amphibious carbon come true.The sludge yield and reaction time decreased,meanwhile,simultaneous removal of nitrogen and phosphorus was reached.In this paper,the denitrifying polyohosphate accumulating organisms were enriched rapidly,which used activated sludge as substrate and nitrite as electron acceptor.The optimal technological condition and impact factors of the system were analyzed.The selection,identification,physiological and biochemical indexes and denitrifying phosphorus and nitrogen removal properties were investigated from the perspective of microbiology.A new bacterium NG2 was obtained via the UV-irradiation.The bacterium was identified by the 16S rDNA sequencing technology and the phylogenetic tree was established.The preparation process of microorganism agent was studied and the nitrogen and phosphorus removal property of the microorganism agent was compared to the activated sludge.The effect of the microorganism agent enhanced reactor to treat the artificially prepared domestic sewage was discussed to provide the theoretical basis for the practical application of denitrifying phosphorus and nitrogen removal technology.The start of A2SBR reactor was surveyed in a periodic manner by means of the two-stage domestication method utilizing the artificial water distribution and DPAO was successfully enriched.The result indicated that the reactor was successfully started after a 36 days'domestication.The typical simultaneous phosphorus and nitrogen removal process took place during the anoxic section in denitrification phosphorus accumulation sludge.Excessive phosphate in the environment was taken in when NO3-was used as the electron acceptor.The phosphorus removal efficiency increased from 44.92%of day 1 to 96.72%of day 36.The single factor experiment was carried on through the static reactor.Many factors,such as the concentration and type of carbon source,sludge age,temperature and pH value,were studied.When sodium acetate was used as the carbon source,the COD of input water was about 200 mg/L,SRT and temperature were set as 15 days and 24?,respectively,and the pH was set as 8.0(anaerobic stage)and 7.5(anoxic stage),the best removal effect was obtained.The phosphorus accumulation bacteria and denitrification bacteria were separated by means of phosphorus accumulation and denitrification specific medium in the stably operated A2SBR reactor,and 14 strains were obtained.The selection experiment was assisted by nitrate reduction gas production test,aerobic phosphorus uptake test and phosphorus absorption/release test.Three simultaneous phosphorus and nitrogen removal strains(N4?P4 and P5)were obtained.The strain N4 had the highest efficiency of phosphorus and nitrogen removal,with a phosphorus removal efficiency of 77.13%and a nitrogen removal efficiency of 83.74%after 24 h.The strain N4 was treated by the UV-irradiation assisted by nitrate reduction gas production test and aerobic phosphorus uptake test,and a high efficiency of phosphorus and nitrogen removal strain NG2 was gained.The result showed that NG2 had the phosphorus and nitrogen removal efficiency compared to N4 was increased by 12.33%and 7.94%,respectively.And the strain NG2 had a better growth advantage compared to the original strain N4.The taxonomic status of NG2(Serial number:KC905050)was confirmed by 16S rDNA sequencing combined with homology analysis.The strain NG2 was finally identified as Gordonia Terrae.The strain NG2 was made into a microorganism agent by fermentation enlarged cultivation on the specific carrier.If succeeded,the microorganism agent was earthy yellow,with the effective viable count>108 CFU/g.It had the same property with the domesticated denitrification phosphorus accumulation sludge.The influence of some factors,such as the bacteria input,carrier ratio,the fermentation liquor dosage and pH,on the performance of the microorganism agent was studied.The result indicated that the best efficiency was obtained when the bacteria input was 20 mL,carrier ratio Wwheat bran:Wcom flour=85:15,the fermentation liquor dosage was 20 mL and the pH of the mixture of fermentation liquor and 2 mL PAM culture solution was 6.5.This microorganism agent had well storage stability and a good performance on denitrifying phosphorus and nitrogen removal under the condition of 25C±5? for about 40 d.It was fit for storage compared to the denitrification phosphorus accumulation sludge.By comparing the treatment effects of artificially prepared domestic sewage with different bacteria input,it was known that the system with a bacteria input of 0.33 g/L has a higher phosphorus and nitrogen removal efficiency.The strengthening effect of the phosphorus and nitrogen removal efficiency compared to the none-bacteria input system was 12.06%and 11.52%,respectively.Moreover,the bacteria input system was more beneficial for the rapid enrichment of denitrification phosphorus accumulation bacteria compared with the none-bacteria input one.