Isolation And Identification Of Phosphorus Accumulating Organisms And Research On Its Characteristics Of Phosphorus Accumulating

In this experiment,sixty-six strains were isolated from different sludges by theYG media and thirty strains were fast growing. After incubation in MOPS-glucose agar plates containing Pi-limitaion and Pi-excess respectively for two days. Eleven strains were formed blue-colony on different medium and they were primary PAO. Seven strains could synthesize PHB and polyP in the A/O process. The phosphorus concentraion rate of seven strains exceed E.coil after 24h aerobic incubation and the GP44 reached 11.92% of its weight. This article would do further research about GP44.Microscopic examination showed its shape was bacilliform and this bacterium appeared by short chain, capsule, no flagellum, sporeforming and gram-negative bacteria. The size of the bacteria was 0.75μm×2.25μm approximately. The colony of GP44 is round, smooth margin, opaque, moist, egg-yellow and fishy smell. The 16S rDNA genes of GP44 and Klebsiella terrigena type strain ATCC 33257^T(AF129442) shows a high level of similarity (96%). According to phenotypic characteristics and phylogenetic analysis, it can be suggested that the strain GP44 has been identified as K. terrigena.Synthesized sewage was the best culture medium for GP44.Logarithmic phase was during four to sixteen hour, the high efficiency of phosphorus removal was at twenty-four hour, and this was the optimum time for tasting the rate of phosphorus removal. In the temperature, pH and aeration experiment, the better temperature range was from 20℃to 40℃,and the best temperature was about 30℃.So influence of temperature is not limited in process of application of PAO to wastewater. But pH and aeration that effected GP44 on growth and phosphorus removal rate were remarkable. The optimal pH value and volume of liquid were 7.5 and 120mL·250mL^-1 respectively. In the carbon source, nitrogen source and metal ion test, glucose and yeast extract were the best carbon source and nitrogen source with high phosphorus removal rate at 59.12%.Mg²⁺,K²⁺and Fe³⁺ could stimulate the phosphorus removal rate of GP44, but Fe³⁺ had restraint to the growth of it.Mn²⁺,Cu²⁺,Pb²⁺,Co²⁺ and Zn²⁺ could restrained the growth and phosphorus removal rate of GP44,and the effect was very remarkable. The others were not. Orthogonal experiment determined the best condition: synthesized sewage as basic medium culture, glucose 0.5g·L^-1,pH7.5, volume of liquid 120mL·250mL^-1 and temperature 30℃,in these four factors, aeration was the main influential factor. The order of phosphorus removal effeced is: aeration > pH> carbon source> temperature. Strain GP44 showed the characteristics of a typical phosphate accumulating organism as it displayed apparent phosphorus accumulated and released in the A/O process. Its release phosphorus was 5.19mg·L^-1whith growth in anaerobic culture for six hours, and accumulated phosphorus was12.34mg·L^-1 in aerobic culture for twelve hours. The phosphorus concentration of medium regulate GP44 to release or accumulate phosphorus to a certain extent. GP44 released phosphorus in the phosphorus concentration of 0.89mg·L^-1,accumulated phosphorus in phosphorus concentrations of 1.78 mg·L^-1,and the phosphorus removal speed and rate were slowly in phosphorus concentration of 17.84 mg·L^-1.The phosphorus concentration in wastewater of 9.62 mg·L^-1to 0.86 mg·L^-1 in the A/O process twice by the municipal wastewater medium. The phosphorus concentration in wastewater is to the twice of Integrated wastewater discharge standard.