Screening Microorganisms For The Bioremediation Of Polluted River And Rearsch Of Its Denitrfication Conditions

Among the phenomenon of river pollution, nitrogen pollution could be the most common, universal and serious. In the treatment of nitrogen pollution, we both need to found ways to eliminate the formation of pollution as well as to keep the ecological environment balance as soon as possible. Considering the above problems, this research mainly adopts biological treatment for the restoration, which includes:1) bacteria which can remove nitrogen pollutants were screened from the environment samples and identified; 2)Use nitrifying bacteria and aerobic denitrficatier to reduce nitrogen contaminants, and optimize the conditions for such progress; 3) discuss the procedures for the produce of nitrifying bacteria.Using selective culture and Bromothymol Blue medium,30 ammonia bacteria strains and 35 aerobic denitrficatiers were picked up from the environment samples. After plate screening and re-screening, an ammonia nitrogen bacteria named AOZ1 which can reduce NH4+-N effectively and an aerobic denitrficatier called GC5 which can effectively removed NO3-N were selceted. AOZ1 was identified as enterobacter sp. after analysis of its physiological and 16S rDNA sequence. GC5 was identified as pseudamonas sp using the same methods.Later, the water purification process was optimized by using the single factor analysis and the orthogonal design method. The optimum parameters of AOZl were: Sodium acetate as carbon sources, C/N ratio 15:1, inoculation quantity 1%, initial pH 7.5, rotational speed 200 r/min, and temperature 30℃. Under such conditions, the removal of NH4+-N was 98.70%. Meanwhile, the optimum conditions of GC5 were as follows: carbon sources ethanol, C/N ratio 15:1, inoculation quantity 1%, initial pH 7.5, rotational speed 160 r/min, and temperature 30℃. Under such condition, the removal of nitrate nitrogen and total nitrogen in simulation sewage were 99.19% and 53.83%, respectively.Finally, Response Surface Methodology (RSM) was used to optimize immersion fermentation conditions for production by Pseudomonas sp.GC5, including 1)introduce Plackett-Burmanwas assay to evaluate 11 factors related to production and four statistically significant factors (sodium citrate, sodium chloride, peptone and inoculation quantity) were selected.2)Then, steepest ascent procedures were applied to define optimal response region for these four factors; 3)finally the optimal factor concentrations were determined adopting RSM analysis, which were sodium citrate 1.0%, sodium chloride 0.05%, peptone 0.43% and inoculation quantity 0.3% respectively. Production after optimization of the fermentation medium increased to 2.91 X 1010CFU/ml.