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题名: 膜生物反应器硝化性能及其微生物群落结构的研究
作者: 余韬
学位类别: 博士
答辩日期: 2010
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 杨敏
关键词: 膜生物反应器 ; 污泥龄 ; 硝化 ; 微生物群落结构 ; 氨氧化细菌
中文摘要:       硝化细菌生长速度缓慢,产率低,对环境因素(DO、pH、温度等)较为敏感,因此,硝化过程往往成为生物脱氮过程的限制性步骤。膜生物反应器(MBR)依靠膜的高效固液分离作用,为系统内保持足量的硝化细菌提供了有利条件,被认为是解决传统工艺中硝化能力不足的重要手段。然而,不同运行条件下,MBR中微生物群落及其硝化活性如何变化仍然不是很清楚。因此,研究不同运行条件下MBR中硝化微生物群落结构的动态变化,阐明特定群落的功能,可以在内在机理和宏观调控之间架起一座桥梁,对于提高工艺的性能具有重要的意义。 本论文通过建立3套并联运行的MBR系统,以无机氨氮废水为研究对象,分别在污泥龄(SRT)为30天、90天和不排泥的工况,考察进水氨氮为100 mg/L和从100 mg/L提高到600 mg/L的条件下,系统硝化性能、硝化活性以及微生物群落结构的动态变化。同时,对处理城市污水的实际污水厂MBR工艺(60,000 m3/d)在启动的前三个月进行跟踪,考察了其硝化活性和硝化细菌群落结构的变化,另外对系统内原生动物及氨氧化古菌(AOA)的结构也进行了初步调查。取得的主要结果如下。 1. 在进水氨氮100 mg/L时,SRT最短(30天)的MBR以快生型的氨氧化杆菌(Nitrosomonas sp.)和亚硝酸盐氧化杆菌(Nitrobacter sp.)为主要硝化细菌,而SRT最长(无排泥)的MBR含有较高比例的慢生型氨氧化螺菌(Nitrosospira sp.)和亚硝酸盐氧化螺菌(Nitrospira sp.)。 2. 逐步提高进水氨氮浓度时,SRT为30天的MBR在氨氮为450 mg/L(容积负荷为0.68 kg NH4+-N/m3·d)时出现NH4+-N和NO2--N的积累,另外两个MBR在氨氮为553 mg/L(容积负荷为0.83 kg NH4+-N/m3·d)时出现NH4+-N和NO2--N的积累。随着氨氮负荷增加,Nitrosomonas sp.在各反应器中均成为优势氨氧化细菌。 3. 适当进行排泥,有利于提高系统对氨氮和亚硝酸盐氮的比氧化速率,并且可以有效地减少系统中细胞胞外分泌物(EPS)等惰性物质的积累,缓解膜的污染,而较长的SRT可保存较高的硝化菌数量,有利于系统抗击高氨氮负荷。因此,SRT控制在90天比较适宜。 4. 在实际MBR的调试中,系统在启动30天时稳定达到平均COD去除率为96 %、BOD去除率为97 %以上、氨氮去除率为98 %以上的效果。由于膜的截留作用,MBR系统中硝化菌比例达到7.2 %,显著高于常规工艺,系统内出现Nitrosomonas oligotropha-和Nitrosomonas ureae等适合贫营养环境的氨氧化细菌,表现出较高的硝化细菌多样性。同时,系统内还存在古硝化细菌,主要为泉古菌Crenarchaeote。 5. 无机配水系统中,肉足虫纲有壳目鳞壳虫是主要的原生动物,其含量随SRT的延长而增加,实际污水厂MBR中原生动物多样性显著增加,鳞壳虫数量较少,但另一种肉足虫纲有壳目表壳虫有较高数量的存在。
英文摘要:       Due to the slow growth rate of nitrifying bacteria and the sensitivity of these organisms to several environmental factors (e.g. DO, pH, and temperature), microbial nitrification is the rate-limiting step in the removal of ammonium from wastewater. Membrane bioreactors (MBR), which keep abundant nitrifiers in the bioreactors through membrane interception, have been found to be advantageous in terms of system stability and compactness for nitrification. The purpose of this study is to provide scientific bases for optimizing operational conditions of MBRs by understanding the impacts of operational conditions on microbial community structures and nitrification performance of MBRs. Three submerged MBRs operated under different SRTs of 30 d, 90 d and no sludge withdrawal were compared in terms of their respective nitrification performance, bioactivity and microbial community structures for treating inorganic ammonia-bearing wastewater. This part of study was designed to understand the impacts of operational conditions on nitrifying community structures and system performance. At the same time, the changes of nitrifiers’ activity and community composition of a full scale submerged MBR system (capacity, 60,000 m3/d) treating sewage were followed over the first three months of operation. Additionally, the ammonia-oxidizing archaea (AOA) and protozoan community structures for some of the MBR system were also investigated. The main research results are as follows. 1. When the influent NH4+-N was approximately 100 mg/L, the fast-growing Nitrosomonas and Nitrobacter sp. bacteria were the dominant AOB and NOB in MBR with the shortest SRT (30 d), while considerable amount of slow-growing Nitrosospira and Nitrospira sp. bacteria existed in the MBR with the longest SRT. 2. As the NH4+-N concentration gradually increased, accumulation of NH4+-N and NO2--N appeared in the MBR with the shortest SRT at an NH4+-N of 450 mg/L (volumetric loading rate, 0.68 kg NH4+-N/m3·d) and in the other two MBRs at 553 mg/L (volumetric loading rate, 0.83 kg NH4+-N/m3·d). Nitrosomonas sp. became the dominant AOB with the NH4+-N loading rate increased. 3. Purge of activated sludge at a proper interval permitted higher ammonia and nitrite oxidation rates and lower EPS concentrations, while longer SRT permitted larger amount of nitrifiers, resulting in high capacity for NH4+-N loading. So an SRT of 90 d was suitable in this study. 4. The full scale MBR system reached a very stable chemical oxygen demand (COD) removal (96 %), biological oxygen demand (BOD) removal (over 97 %) and NH4+-N removal (over 98 %) within three months. The MBR system was characterized with the higher diversity and percentage of nitrifiers (7.2 %) than the conventional activated sludge processes. The oligotrophic nitrifiers like the Nitrosomonas oligotropha- and Nitrosomonas ureae-like bacteria, appeared due to the interception by membrane. Ammonia-oxidizing archaea (AOA) were also detected with most of sequences closely related to Crenarchaeote. 5. Euglypha belonging to Sarcodina class, Testacea order was the dominant protozoan in MBR systems fed with the inorganic ammonia-bearing wastewater. The full scale MBR system treating sewage was characterized with much higher protozoan diversity, with Arcella belonging to Sarcodina class as one of the dominating group.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35040
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
余韬. 膜生物反应器硝化性能及其微生物群落结构的研究[D]. 北京. 中国科学院研究生院. 2010.
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