Isolation And Identification Of A Thermophilic Aerobic Denitrifier And Its Denitrification Characteristics

The development of the global economy and society inevitably brings serious environmental problems. Especially the phenomenon of water eutrophication is increasing. It has become a serious global environmental problem. Nitrogen, the main water pollutant, is one of culprits causing deterioration of water quality and water eutrophication. Biological nitrogen removal method at present is considered more cost-effective and the most promising approach. However, the most existing biological nitrogen removal processes are suitable for sewage treatment at middle and low temperature. To deal with common high temperature industrial wastewater requires cooling process, which increases infrastructure and operating costs. At the same time, the traditional biological nitrogen removal general respectively experience two completely separate process, aerobic autotrophic nitrification and anaerobic heterotrophic denitrification. Therefore, isolating the bacteria-that has a capacity of ability simultaneously aerobic denitrification and heterotrophic nitrification under high temperature condition and studying the mechanism of denitrification, in order to implement simultaneous nitrification and denitrification, have become a hot research topic at home and abroad. Meanwhile the research of nitrification and denitrification bacteria not only provides a theoretical basis for eutrophication governance, but also has positive significance for its further development, utilization and engineering applications of water eutrophication treatment.A thermophilic aerobic denitrification strain named XF3was isolated from the activated sludge of sequencing batch reactor of a sewage treatment plant in Taiyuan city. The growth and nitrogen removal performance were studied, the results are as follows:(1) Based on the morphology observation, physiological and biochemical experiments, the strain showed gram negative, round and milky white colony, smooth and opaque surface, Its16SrDNA sequences had98%homology with Brevibacillus borstelensis16S rDNA. Therefore, the strain XF3was preliminarily identify the strains XF3as Brevibacillus.sp., and named it Brevibacillus sp. XF3.(2) Single factor experiments were used to investigate the influence of carbon source, C/N, pH, inoculum size on the growth of strain Brevibacillus sp. XF3and denitrification characteristics. The results indicated that the optimum conditions were as follows; carbon source was sodium succinate, C/N ratio12:1, pH value7, inoculum size10%(volume fraction). Under the optimal conditions, the nitrate degradation rate reached92.9%after cultured48h, the whole process produces only a small amount of nitrite nitrogen accumulation.(3) It was also shown that the strain had a good capability of heterotrophic nitrification:the ammonia nitrogen concentration was reduced from73mg/L almost to zero within48hours. Single factor experiment showed that the optimal condition of ammonia nitrogen removal of strain Brevibacillus sp. XF3were pH value7, the optimum C/N12:1.(4) Thermophilic aerobic denitrification-heterotrophic nitrification strain was isolated and identified. Its characteristics of ammonia nitrogen removal was also studied, In order to lay the theoretical foundation for nitrogen removal, simutaneously nitrification and denitrification, provide the reference for practical engineering, study the simultaneously nitrification and denitrification process, and offer the microbial source by improving the efficiency of biological enhancement technology.