Study On The Characteristics Of DPB And On The Exeperiment Of DPB Bioaugentation Technique

In recent years, as the phenomenon of eutrophication was aggravating, the discharge standard of nitrogen and phosphorus in wastewater was increasingly strict.There were still some shortcomings in conventional biological denitrification and phosphorus removal processs, the defect was mainly manifested in the conflict between phosphorus accumulating bacteria and denitrifying bacteria for carbon, making it hard to meet the requirements of denitrification and phosphorus removal at the same time. The discovery of denitrifying phosphorus accumulating bacteria (DPB) successfully solved the contradiction of carbon source and inconsistent of sludge age, it provided a new way to the development of denitrification and phosphorus removal technology. The theory of denitrifying denitrification and phosphorus removal was used to analyze the biological characteristics of DPB, and study the growth of strains and denitrification and phosphorus removal characteristics, provided theory basis for the application of strain on the biological strengthening technology.The three strains of DPB which had purified (from the anaerobic activated sludge in the stable operation of the An/O/A/O SBR system) were used to Morphological observation and physiological and biochemical characteristics of strains; Study on the Strains’optimal growth environment and the best conditions of denitrification and phosphorus removal by changing the culture conditions including temperature, pH, carbon sources, electron acceptor concentration. Mixed with three strains, test the denitrification and phosphorus removal effect of hybrid strains, and confirm the optimum mixing ratio;Add the strains to the SBR system,compared the change of denitrification and phosphorus removal effect.Two strains in the three were Delftia strains(Delflia), named De2 strain and De3 strain respectively, another one was Pseudomonas(Pseudomonas), named Ps5 strain. Through the test of growth curve, logarithmic growth period of De2 strain was 6-12h, De3 and Ps5 were 6-15h and 5-16h respectively. The influence of environmental factors on biological nitrogen removal was tested by changing growth temperature, pH, carbon sources, electron acceptor conditions. The results show that when the temperature was 20～30℃, phosphorus removal rate of De2, De3 and Ps5 strain reached 65%,80% and 68%, denitrification rate reached 68%,84% and 84%. When the pH value was 7.5, phosphorus removal rate of De2, De3 and Ps5 strain were 73%, 87% and 79% respectively, denitrification rate were 75%,85% and 80% respectively. When carbon source was sodium acetate, nitrogen removal effect were best, phosphorus removal rate were 76%,88% and 78% respectively, denitrification rate were 70%,86% and 75% respectively. When electron acceptor was NO3- and concentration was 30-40 mg/L, phosphorus removal rate of three strains was over 76%,87% and 76% respectively. When the electron acceptor was NO2-and concentration was 20-25 mg/L, phosphorus removal rate of three strains was over 65%, 74% and 72% respectively.When nitrite wse used electron acceptor and after 21 hours’cultivated, The results showed that the phosphorus removal rate of De2, De3 and Ps5 strains were 74%,81% and 75%, the denitrification rate were 81%,85% and 82% respectively. Mixing De2 and De3 in different proportion, tested denitrification and phosphorus removal effect under different mixing proportion, it showed that when the De2 and De3 were mixed in the volume ratio of 1:2, the phosphorus removal rate of mixed strains was 91%, the denitrification rate was 92%. when De2, De3 and Ps5 strains were mixed under the proportion of in 2:4:3, the denitrification and phosphorus removal effect of mixed strains were best, phosphorus removal rate was 91%, the denitrification rate was 96%.The test results by biological enhancement show that denitrification and phosphorus removal effect were increased 8% and 6% respectively when add the strains to the system. When reached at the same effect,the reaction time was shorter 30 minutes,and the effluent water can reach A standard ruled in the "Discharge standard of pollutants for municipal wastewater treatment plant".When added Denitrifying Phosphorus Accumulating Bacteria to the SBR system,it can improved the effect of nitrogen and phosphorus and also shorten the reaction time.