节点文献
耐盐异养硝化—好氧反硝化菌的筛选方法与脱氮机制及其生物强化短程硝化系统的研究
【作者】 曲洋；
【导师】 张培玉；
【作者基本信息】 青岛大学 ， 环境工程， 2010， 硕士
【摘要】 研究了一种新的富集驯化耐盐异养硝化-好氧反硝化菌的方法。采用高C/N、逐渐降低DO、菌体对数生长期转接以及增加培养液中海水比例的方式完成了耐盐异养硝化菌的富集和驯化,并分离出38株异养硝化-好氧反硝化菌。经复筛得到1株高效耐盐异养硝化-好氧反硝化菌,命名为qy37。通过对菌株qy37的形态观察、生理生化试验和16S rDNA序列分析,确定其为假单胞菌属(Pseudomonas)。对菌株qy37的异养硝化作用和好氧反硝化作用的机制进行了比较。在以NH4Cl为氮源的异养硝化系统内,该菌32 h内使NH4+-N由138.52 mg/L降至7.88mg/L, COD由2408.39 mg/L降至1177.49 mg/L, NH2OH最大积累量为9.42 mg/L, NO2--N最大积累量仅为0.02 mg/L,推测该菌将NH2OH直接转化为N2O和N2从系统中脱除。在以NaNO2为氮源的好氧反硝化系统内,该菌24 h内使NO2--N由109.25 mg/L降至2.59 mg/L, NH2OH最大积累量为3.28 mg/L。好氧反硝化系统与异养硝化系统相比菌体生长量高,TN去除率低,COD消耗量低,NH2OH积累量低,并且检测到NO3--N的积累。认为好氧反硝化在菌体生长和能量利用方面比异养硝化更有效率。对异养硝化-好氧反硝化混合系统进行了研究。在异养硝化-好氧反硝化混合系统内,16 h NH4+-N去除速率比异养硝化系统提高了37.31%。混合系统的NH2OH积累量低于异养硝化系统和好氧反硝化系统,但N2O产出量高于二者。这些研究可为异养硝化-好氧反硝化菌在污水处理工程中的应用提供参考。对异养硝化-好氧反硝化菌应用于短程硝化系统的可行性进行了研究。采用生物强化技术将4株高效异养硝化-好氧反硝化菌投入耐盐短程硝化污泥中,考察了其对含海水污水的SBR短程硝化系统的强化效果,并比较了强化系统与原系统的差异性。结果表明,强化系统的NO2--N最大积累量比原系统降低34.92%,而且到达NO2--N最大积累量的时间比原系统提前2 h。强化系统的TN和COD在硝化段中后期持续降低,硝化结束时其TN和COD去除率比原系统高出15.24%和5.39%, NH4+-N去除率和亚硝化率比原系统高出6.85%和14.47%。强化系统的pH比原系统高0.46,而ORP低25.84 mV。认为强化系统的性能提升是强化菌的异养硝化作用和好氧反硝化作用引起的。当受到70%海水盐度冲击时,强化系统的稳定性高于原系统,强化菌的加入有效的抑制了系统从短程硝化向全程硝化转变的趋势。在强化系统与原系统运行的各阶段,强化菌种的数量发生了变化,且随着系统排泥强化菌大量流失。本研究为异养硝化-好氧反硝化菌应用于短程脱氮系统的可行性提供理论参考。
【Abstract】 A new method for enrichment and domestication of heterotrophic nitrification-aerobic denitrification bacteria was studied. The enrichment and domestication was accomplished by adopting high C/N ratio, gradually reducing DO, inoculating domestic bacteria to new culture medium in log phase and increasing the proportion of sea water for culture medium, and 38 strains were screened in this process. Furthermore, a train qy37 of heterotrophic nitrifying bacteria were isolated from enrichment and domestication system. In the light of its morphological and physiological characters as well as its sequence analysis of the 16S rDNA, strain qy37 was identified as Pseudomonas sp.The mechanism of heterotrophic nitrification and aerobic denitrification was compared. The characterization in nitrogen removal of a heterotrophic nitrification-aerobic denitrification bacteria qy37 was studied. A strain coded as qy37 which had simultaneous heterotrophic nitrifying and aerobic denitrifying ability was screened. In the light of its morphological and physiological characters as well as their sequence analysis of the 16S rDNA, strain qy37 was identified as Pseudomonas sp. In heterotrophic nitrifying system utilized ammonium chloride as nitrogen source, the concentration of NH4+-N reduced from 138.52 mg/L to 7.88 mg/L and COD reduced from 2408.39 to 1177.49mg/L by strain qy37 in 32 hours, the maximum accumulation of NH2OH and NO2--N were 9.42 mg/L and 0.02 mg/L respectively, it was speculated that NH20H was transformed to N2O and N2 directly by strain qy37. In aerobic denitrifying system utilized sodium nitrite as nitrogen source, the concentration of NO2--N reduced from 109.25 mg/L to 2.59 mg/L by strain qy37 in 24 hours, and the maximum accumulation of NH2OH was 3.28mg/L. Compared with heterotrophic nitrifying system, aerobic denitrifying system had a higher bacterial growth whereas the lower removal rate of TN and COD, as well as the accumulation of NH2OH. NO3--N was also detected In aerobic denitrifying system. It is considered that the upgrowth of bacterium and utilization of energy in aerobic denitrifying system were more efficient than that in heterotrophic nitrifying system.The heterotrophic nitrification- aerobic denitrification system was studied. In heterotrophic nitrification- aerobic denitrification system, the removal rate of NH4+-N improved 37.31% in 16 hours than that in heterotrophic nitrifying system, the accumulation of NH2OH was less but N2O was higher than that in both heterotrophic nitrifying system and aerobic denitrifying system. These results should be useful for practical application of heterotrophic nitrification- aerobic denitrification bacteria in sewage disposal.The feasibility of heterotrophic nitrification- aerobic denitrification bacteria applied in shortcut nitrification system was studied. Four heterotrophic nitrification-aerobic denitrification strains mixed with halotolerant activated sludge was added into SBR in order to test their bioaugmentation ability for shortcut nitrification system, which was treating for sewage containing sea water, and the difference between bioaugmentation system and original system was compared. The results showed that the maximum accumulation of NO2--N in bioaugmentation system was 34.92% lower than that in original system, and the time of maximum accumulation of NO2--N was 2 hours earlier than that in original system. The TN and COD was continuously decreasing in the later phase of nitrification in bioaugmentation system, and finally the removal rate of TN and COD were 15.24% and 5.39% higher than that in original system respectively, as well as the removal rate of NH4+-N and the nitrosation rate were 6.85% and 14.47% higher than that in original system. And the pH was 0.46 higher than that in original system, whereas the ORP was 25.84 mV lower. It was considered that the function of heterotrophic nitrification-aerobic denitrification bacteria should strengthen the performance of bioaugmentation system. When the seawater content raised to 70%, the stability of bioaugmentation system was better than that in original system, and the current that transforming shortcut nitrification to complete nitrification was restrained by heterotrophic nitrification- aerobic denitrification bacteria effectively. The number of heterotrophic nitrification-aerobic denitrification bacteria was changed when bioaugmentation system and original system ran in different phase and the bacteria had a great loss with the discharge of activated sludge. These results may provide a theoretical reference about the feasibility that the heterotrophic nitrification-aerobic denitrification bacteria applied in shortcut nitrification system.