【作者】 肖晶晶；

【导师】 朱昌雄；

【作者基本信息】 中国农业科学院 ， 农业微生物学， 2011， 博士

【摘要】 富营养化问题是当今世界面临的主要水污染问题之一,水体富营养化的发生及发展是多因素共同作用的结果,其中营养盐增加是发生富营养化的主要因素。本研究针对水体的氮污染,研究固定化脱氮菌群技术,以实现污水脱氮目的,从而减少富营养化发生的风险。本文首先从活性污泥、土壤等环境样品中筛选氨化菌、异养亚硝酸菌、硝酸菌和反硝化菌,通过观察菌株的菌落和菌体表观形态、测试生理生化特征和16S rDNA序列分析,综合以上特征对各菌株进行鉴定。取具有四种不同功能菌株各一株,构建脱氮菌群组合,筛选高效降低有机氮和氨氮浓度,且不积累亚硝态氮和硝态氮的菌群组合。研究制备固定化脱氮菌群颗粒,优化颗粒制备配方,同时对颗粒质量进行评价,并建立了评价方法。将固定化脱氮菌颗粒用于自行研制的污水处理反应器中,研究其处理效果。本文汇集了脱氮菌群、微生物固定化和污水处理反应器工艺,并将其有效结合,此技术具有高效净化氮污染型富营养化水或深度处理含氮污水的功能,为微生物处理含氮污水提供了理论依据和实际指导意义。本研究主要内容及结果如下:1.氨化菌、亚硝酸菌、硝酸菌和反硝化菌的筛选及菌种鉴定本文从活性污泥、鱼塘水和土壤等环境中,通过富集、初筛得到196株细菌,其中氨化菌112株、亚硝酸菌46株、硝酸菌25株和反硝化菌13株;通过复筛得到18株高效菌株,其中氨化菌5株、亚硝酸菌4株、硝酸菌4株和反硝化菌5株。对这些菌株进行菌种鉴定,部分鉴定结果如下, A亚-C-3为枯草芽孢杆菌(Bacillus subtilis),G硝-C-3为门多萨假单胞菌(Pseudomonas mendocina),M氨-4为枯草芽孢杆菌(Bacillus subtilis),R反-5为类产碱假单胞菌(Pseudomonas pseudoalcaligenes)。2.脱氮菌群的构建选取氨化、亚硝化、硝化和反硝化功能菌各一株组成脱氮菌群组合,共构建72个组合。依据筛选高效降低有机氮和氨氮浓度,且不积累亚硝态氮和硝态氮菌群组合的原则,筛选获得AMGR组合脱氮效率最高,此组合AGMR处理污水48h时总氮去除率为65.32%,96h时总氮去除率达95.27%。3.固定化脱氮菌颗粒的制备、颗粒配方优化及质量评价采用聚乙烯醇和海藻酸钠包埋微生物,优化颗粒制备配方,优化结果为海藻酸钠最适浓度0.25%,活性炭含量2%,PVA浓度12%,交联时间为24h。以优化后的配方制备固定化亚硝酸菌Bacillus subtilis A颗粒并测试其处理含氮污水的效果,结果表明碳源有利于包埋菌颗粒对氨氮的去除,包埋两种不同浓度菌的颗粒除氨氮效果差异不显著。此外,固定化脱氮菌群颗粒处理模拟富氮营养水和模拟河水效果比固定化单菌颗粒好。本文提出了固定化微生物颗粒质量评价方法,从物理、化学和微生物三方面评价颗粒的质量。4.固定化Bacillus subtilis A颗粒在固定床反应器中处理氨氮污水效果研究通过试验发现固定化Bacillus subtilis A颗粒在固定床反应器中运行需经一周的驯化期才能达到稳定运行状态。在连续运行中,将HRT控制为20min,氨氮去除率可达90%以上;高溶氧(42.3 - 58.7%)有利于氨氮的去除;污水中较合适的碳氮比为10。5.固定化脱氮菌群颗粒在反应器中处理含氮污水的研究采用装载固定化复合菌颗粒的反应器系统分别以固定床和流化床方式处理含氮污水,研究不同条件参数对污水处理的影响,优化运行参数及运行方式。①采用固定床连续运行方式,较合适的HRT为20min,当溶氧为36.7–59.8%、碳氮比为20:1时总氮去除率可接近100%。②采用流化床间歇运行方式,停留时间为140min,溶氧为56.8~71.6%时,总氮去除率可接近100%。本反应器系统适于处理初始氮浓度低于20mg/L的微污染水。③采用流化床连续运行,停留时间为12h时,溶氧为43.0~56.8%条件下,总氮的去除率可达78.12%-80.86%。此外,对流化床和固定床处理含氮污水的运行效果进行比较,流化床处理效率更高。6.固定化脱氮菌颗粒处理含氮污水的机理探讨脱氮菌处理含氮污水过程中,氮的转化脱除起主要作用;通过电镜观察发现固定化颗粒内的脱氮菌经驯化后会出现分布上的演替,主要分布在颗粒外层;初步探讨脱氮菌群产气成分以氮气为主。更多还原

【Abstract】 Nowadays eutrophication is one of more severe problems occurred in water pollution,and the occurrence and deterioration of eutrophication are caused by many factors, among which increase of nutrient substance content is the main one. In this study, aiming at removing nitrogenous substance from the pollution water we developed an immobilization technology of bacterial consortium for nitrogen removal to reduce nitrogen concentration in sewage and decrease the risk of causing eutrophication. The ammonifier, heterotrophic nitrosobacteria, nitrobacteria and denitrifying bacteria were screened from activated sludge, soil and other niches. The strains were identified by observation of colony morphology, physiological and biochemical characteristics and 16S rDNA sequence analysis. The bacterial consortium for nitrogen removal was composed of four strains that had different functions and able to reduce organic nitrogen and ammonia nitrogen concentration efficiently without accumulating nitrate and nitrite. The granule immobilization technology of nitrogen removal bacterium consortium was researched, the composition was optimized and the quality evaluation system of immobilized granules was established. The treating effect of the immobilized granule on nitrogenous sewage in self-developed sewage treatment reactor was studied. This paper provided theoretical basis and practical guidance for nitrogenous sewage treatment by microbial means. It has combined immobilization technology of nitrogen removal bacterial consortium with the technique of sewage treatment reactor, which had great purification effect on nitrogenous sewage. The following conclusions were mainly drawn:1. Screening and identification of ammonifier, heterotrophic nitrosobacteria, nitrobacteria and denitrifying bacteria196 bacteria including 112 ammonifiers, 46 heterotrophic nitrosobacteria, 25 nitrobacteria and 13 denitrifying bacteria were obtained through enrichment and initial screening from activated sludge, fish pond water and soil. 18 high efficient strains including four ammonifiers, four heterotrophic nitrosobacteria, four nitrobacteria and five denitrifying bacteria were gained through secondary screening. A nitroso-C-3, G nitro-3, M ammonia-4 and R denitro-5 were identified as Bacillus subtilis, Pseudomonas mendocina, Bacillus subtilis and Pseudomonas pseudoalcaligenes, respectively.2. Construction of nitrogen removal bacterial consortiumThe bacterial consortia were constructed from four strains which had respective function, and there were 72 consortia in all. The AMGR consortia were screened out according to the principle of reducing organic nitrogen and ammonia nitrogen concentration efficiently and accumulating no nitrite and nitrate nitrogen. The denitrogen rate of AMGR consortia was higher than others. The denitrogen rate of AMGR was 65.32% within 48h and 95.27% within 96 h.3. Preparation of immobilized consortium granules, optimization of granule ingredient and quality evaluation.Polyvinyl alcohol (PVA) and Na-alginate were used as a gel matrix to entrap microbes within the beads, and optimized compositions were 0.25% Na-alginate, 2% activated carbon, 12% PVA and linking cross time of 24 h. Immobilized nitrosobacterium Bacillus subtilis A beads were prepared under the optimized formula. The results showed the carbon source was beneficial to ammonia nitrogen removal and granules with two different bacterial concentration have similar effect on removing ammonia nitrogen. Compared with immobilized single bacterium, the immobilized consortium had better effect of removing nitrogen in the simulated eutrophic water and river. This paper proposed the quality evaluation system of immobilized microbe beads in aspect of physical, chemical and microbial index.4. Effect of immobilized Bacillus subtilis A granule on ammonium nitrogen-rich sewage in bioreactor systemImmobilized Bacillus subtilis A beads would be in the steady state after one week’s domestication. In the continuous treating process, when HRT was 20 min, the concentration of ammonium nitrogen effluent was lower than 0.3 mg/L, and removal rate of ammonia nitrogen was more than 90%; Compared with low DO condition, high DO was beneficial to removing ammonium nitrogen; More suitable carbon nitrogen ratio was 10.5. Effect of immobilized bacterium consortium on nitrogen removal in sewage treatment reactorImmobilized nitrogen removal bacterium beads would work in fixed bed reactor and fluid bed reactor, and this paper researched the effect of sewage treatment under different parameters and optimized these parameters.①In fixed bed continuous flow way, the results showed HRT of 20 min was a suitable retention time, at which time the removal rates of effluent total nitrogen was close to 100%.②In fluid bed intermittent flow way, the removal rate of effluent total nitrogen was close to 100% when HRT was 140min and DO was between 56.8% and 71.6%. This reactor system was fit for slight pollution water, initial nitrogen concentration in which was below 20 mg/L.③In fluid bed continuous flow way, the removal rates of total nitrogen were between 78.12% and 80.86% under HRT of 12h and DO of 43.0~56.8%. In addition, compared fixed bed reactor, the treatment effect of fluid bed reactor was better.6. The theoretical discussion on nitrogen removal of immobilized denitrogen bacterial consortiumIn the process of nitrogenous sewage treatment with immobilized denitrogen bacterial consortium, the nitrogen removal played major role; Observing with the scanning electron microscopy, we found that the microbes after domestication would show succession in distribution, mainly at surface layer of beads; The dominant gas produced by bacterial consortium was the nitrogen gas.更多还原