低温硝化细菌的筛选及其在低温污水处理中的初步应用研究

发布时间：2018-05-23 14:32

  本文选题：北极海洋沉积物 + 低温硝化细菌　； 参考：《青岛大学》2017年硕士论文

【摘要】：随着我国城市化的快速发展,城市用水量也随之大幅增高,如何提高污水处理效率,保障水环境质量成为城市发展的重要课题。寒冷地区冬季低温污水的生物处理长期存在着处理效果差、难以达标排放等难题,这主要是由于低温对活性污泥的吸附沉降性能和微生物的生长发育等均有显著影响。因此,分离高效的低温硝化细菌并用于低温污水的处理,是解决我国北方地区冬季污水厂出水水质难以达标的有效方法之一。极地特殊的环境与气候造就了独特的极地微生物生态系统,是微生物新菌种资源的宝库。根据菌落形态特征,利用4种硝化细菌筛选培养基从12个站位的北极海洋沉积物中分离筛选,并获得16S rRNA基因有效序列的低温硝化细菌达81株;基于16S rRNA基因的相似性分析与系统发育分析表明,分离到的菌株分属于细菌域的4个门、4个纲、8个目、16个科、22个属、30个种,其中γ-变形杆菌纲(γ-Proteobacteria)占大多数;有1株菌株与模式菌株的16S rRNA基因序列相似性小于97%,为潜在的新种。对不同属的代表菌株的生理生化测定表明,大多数菌株具有产蛋白酶、脲酶和β-半乳糖苷酶等胞外水解酶和利用葡萄糖、甘露醇和麦芽糖等各种碳源生长的能力。对18株菌株的温度和盐度生长范围的测定表明,大多数硝化细菌的温度和盐度生长范围在0-30℃和0-90,大部分菌株最适温度为20℃,最适盐度为15,既能满足低温下菌株保持较高的生长活性,又具有较广的对盐度适应范围,对环境有很好的适应性。将对温度和盐度适应能力较强的菌株接种到筛选液体培养基中,筛选出生长情况较好的菌株R14-ZY-5、CC6-YX-43、NB04-YY-61、CC6-ZY-68、CC6-YY-73和CC6-YY-74,并分别对其进行模拟污水的硝化与反硝化测试,经测试菌株R14-ZY-5和CC6-YY-74具有较好的脱氮能力,可进行混合菌群的构建。此外,从2株细菌CC6-ZY-68和CC6-YY-74中成功克隆到反硝化途径的关键酶基因nirS。选择菌株R14-ZY-5和CC6-YY-74构建混合菌群,并分别研究C/N、温度和盐度对其脱氮效果及COD去除率的影响。结果表明,混合菌群在C/N为8-14均具有较好的脱氮能力,在C/N=11时处理效果最好,48 h时NH4+-N去除率可达93.41%,NO3--N去除率可达99.96%;当C/N=11时,菌群在温度为5℃-20℃均具有较高的脱氮能力,48 h时去除率相差甚微。在温度为15℃时处理效果最好,48 h时NH4+-N去除率达91.70%,NO3--N去除率达99.96%,COD去除率达87.28%;菌群在盐度为15-45的范围内均具有较好的脱氮能力,在盐度为30时脱氮处理效果最好,48 h时NH4+-N去除率达92.57%,NO3--N去除率达99.96%,COD去除率达91.35%。本研究将为北方地区寒冷季节低温生活污水的生物处理提供新的菌种资源,并为今后将其运用到工程实践中提供了基础资料和科学依据。
[Abstract]:With the rapid development of urbanization in China, the amount of urban water consumption has also increased significantly. How to improve the efficiency of sewage treatment and ensure the quality of water environment has become an important topic of urban development. The biological treatment of low temperature sewage in cold region has some problems such as poor treatment effect and difficulty in discharging. This is mainly due to the significant influence of low temperature on the adsorption and settling performance of activated sludge and the growth and development of microorganisms. Therefore, it is one of the effective methods to separate high-efficient low-temperature nitrifying bacteria and to treat low-temperature sewage. The special environment and climate of the polar region create a unique polar microbial ecosystem, which is the treasure house of new microbial species. According to the morphological characteristics of the colony, 81 strains of low-temperature nitrifying bacteria with effective 16s rRNA gene sequence were isolated and screened from 12 stations of Arctic marine sediments by four kinds of nitrifying bacteria screening medium. The similarity analysis and phylogenetic analysis based on 16s rRNA gene showed that the isolated strains belonged to 4 phyla, 4 classes, 8 orders, 16 families, 22 genera and 30 species, of which 纬 -Proteobacteria accounted for the majority. The sequence similarity of 16s rRNA gene between one strain and the model strain is less than 97%, which is a potential new species. The physiological and biochemical tests of the representative strains of different genera showed that most strains had the ability to produce protease, urease and 尾 -galactosidase, and to grow with various carbon sources such as glucose, mannitol and maltose. The growth range of temperature and salinity of 18 strains was determined. The results showed that the temperature and salinity of most nitrifying bacteria ranged from 0-30 鈩，

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