【作者】 倪寿清；

【导师】 高宝玉； 顾若川； 宋士武；

【作者基本信息】 山东大学 ， 环境工程， 2010， 博士

【摘要】 相比于传统生物脱氮,厌氧氨氧化(anammox)过程是一种创新而卓越的选择,该过程使用亚硝酸氮作为电子受体,在自养条件下将氨氮氧化为氮气。这一过程是环境友好和可持续过程,其具有很多独特的优点,如不需要投加外部碳源,低能耗,低操作成本和剩余污泥产量。然而,该过程也有着鲜明的缺点,包括anammox细菌生长率较低,可利用的接种污泥源有限,细菌对氧气、有机物甚至基质等多种物质敏感而易受其抑制,这些不足都严重限制了anammox过程的应用。为了克服anammox过程应用中的困难,本论文从不同角度研究了anammox过程性能和微生物特性,主要研究内容和结果如下：Ⅰ.通过将一组无纺布膜组件和厌氧反应器相连接,本文设计了一个新型反应器结构来研究anammox细菌的富集。通过形成聚集体和膜内表面生物膜,anammox无纺布膜反应器(ANMR)表现出较好的生物量保持能力。成熟生物膜形成后,没有膜污染问题发生。经过8个月的培养后,反应器氮负荷和去除率分别达到1263mg N/L/d和1047.5 mg N/L/d,最大氨氮消耗率是51 nM/mg protein/min。反应器稳定阶段,NH4+-N和NO2--N平均去除效率分别是90.9%和95.0%。形态学观察表明,anammox聚集体和生物膜表现较高程度的紧密度。同时,实时聚合酶链反应(PCR)分析显示,anammox细菌的富集程度达到97.7%。Ⅱ.本论文使用不同数学模型研究了ANMR反应器的脱氮动力学,同时首次研究了anammox过程氮气产量动力学。模型动力学和模型测试均表明Grau二级基质去除模型和Van der Meer and Heertjes气体产量模型是现有模型中最适合描述anammox过程脱氮和氮气产量的模型。Ⅲ.厌氧氨氧化颗粒污泥反应器通常采用厌氧／好氧颗粒作为污泥源,由于共竞作用,这种接种方法使得其他细菌的洗出和：anammox菌的富集十分缓慢。本论文通过调查失活产甲烷颗粒与anammox菌的相互作用,发现失活产甲烷颗粒适合用来实现anammox快速颗粒化,尤其是采用高浓度含氮废水启动时。研究中,反应器启动阶段进水NO2--N浓度明显高于已发表的对anammox菌可能产生毒性的水平。三个月的培养可观察到直径1.3±0.4 mm的anammox颗粒,分子学分析显示此时颗粒中65%以上的细胞是anammox细菌。Anammox细菌可以利用失活产甲烷颗粒骨架并在颗粒内增殖是短时间内颗粒中anammox菌实现高纯度的主要原因。在4个月的操作时间里,氮负荷由141 mg/L/d增加到180 mg/L/d,同时总氮去除率高达96.0±0.6%。形态学观察证明了胞外多聚物在颗粒结构中的重要作用。Ⅳ.厌氧氨氧化过程的应用部分受制于anammox接种污泥的匮乏。近来,欧洲与亚洲均成功运行了anammox处理厂。本章研究了从国外引进污泥接种反应器处理高浓度含氮废水并实现快速启动的可能性。实验表明,反应器可实现快速启动,并且较长时间内,反应器可以达到高氮去除率,稳定运行时,NH4+-N和NO2--N的去除率稳定在95%-99.2%和97.7%-99%之间。反应化学计量学分析显示,NO2--N转化量和NO3--N生成量与NH4+-N消耗量的摩尔比是1.26±0.02：1和0.26±0.01：1,与经验值基本吻合。修正的Stover-Kincannon模型首次应用于anammox颗粒反应器,其具有较高的相关系数,并得出颗粒反应器具有27.8kg/m3/d的高除氮能力。电镜及荧光原位杂交技术被用来表征Anammox颗粒。实时PCR技术显示,颗粒微生物群落中anammox细菌占91.4-92.4%。Ⅴ.本文还系统研究了包括絮状污泥、颗粒污泥和由失活产甲烷颗粒富集的污泥在内的3种anammox污泥的性能、抑制和活性恢复过程。不同污泥性能比较和动力学研究得出,接种由失活产甲烷颗粒富集的anammox污泥的反应器具有最高的除氮能力,之后是颗粒污泥反应器和絮状污泥反应器。研究发现988.3 mgNH4+-N/L和484.4 mg NO2--N/L能完全抑制颗粒反应器活性,但仅能引起絮状污泥反应器50%活性降低。抑制后,接种絮状污泥和颗粒污泥的反应器可以通过降低反应器进水得到完全恢复,而接种失活产甲烷颗粒培养的anammox污泥反应器只能重拾75%活性。本研究中,污泥中anammox菌纯度是比污泥类型更适合评价反应器恢复能力的参数。同时发现,游离氨比游离亚硝酸更适合来监测anammox反应器抑制和恢复过程。Ⅵ.有机物的存在会对anammox过程产生负面影响。实际废水中不可避免地含有有机物,本文第一次研究了有机物的存在下,颗粒污泥的性能。在没有投加有机物时,颗粒反应器表现出极好的NH4+-N和NO2--N去除率。实时PCR分析得出细菌群体中anammox细菌占89.3-90.6%,少量反硝化菌也存在于污泥中。低浓度有机物并没有显著影响NH4+-N和NO2--N去除率,但却通过反硝化菌提高了总氮去除率。高浓度有机物抑制了anammox活性,使得NH4+-N去除率降低,而NO2--N去除率却没有因有机物存在而受到影响。当反应器进水COD为400 mg／L时,实时PCR分析显示污泥中anammox菌减少,而反硝化菌数量有增加趋势。文中定义NH4+-N去除率降为80%时,COD浓度为有机物对anammox活性抑制的阈值,实验得出该值为308 mg COD/L,可见anammox颗粒污泥比絮状污泥对有机物有更高忍受能力。更多还原

【Abstract】 The anammox (anaerobic ammonium oxidation) process is a novel and promising alternative to biological treatment of ammonium, in which ammonium is oxidized to nitrogen gas using nitrite as the electron acceptor autotrophically. This process can be considered as an environmental friendly and sustainable process with several advantages, such as no need for addition of external carbon sources, low power consumption, low operational costs and biomass yields. However, this process has strong drawbacks, including slowly bacteria growing rate, limited availability of biomass and being sensitive to oxygen, organic matters and substrate, which limit the application of this process critically. In order to solve these difficulties, performance of anammox process and anammox microbial characteristics were studied in this dissertation. Main contents and conclusions obtained from this research are concluded as follows:Ⅰ. An innovative reactor configuration for anammox enrichment by connecting a non-woven membrane module with an anaerobic reactor was developed in this study. The anammox non-woven membrane reactor (ANMR) exhibited high biomass retention ability through the formation of aggregates in the reactor and biofilm on the interior surface of the non-woven membrane. No fouling problems occurred on the membrane after the development of mature biofilms. At steady state, the average ammonium and nitrite removal efficiencies were 90.9% and 95.0%, respectively. The enrichment of anammox bacteria was quantified by real-time polymerase chain reaction (PCR) analysis as 97.7%.Ⅱ. Different mathematical models were used to study the process kinetics of the nitrogen removal in the ANMR. The kinetics of nitrogen gas production of anammox process was first evaluated in this paper. Both model kinetics study and modeling test showed that the Grau second-order model and the Van der Meer and Heertjes model seemed to be the best models to describe the nitrogen removal and nitrogen gas production in the ANMR, respectively.Ⅲ. In previous granular anammox process, the washout of other species and enrichment of anammox biomass were very slow because of the competition of the coexisting bacteria. In this study, inactive methanogenic granules were proved to be suitable for rapid anammox granulation under high nitrogen concentrations by investigating their interaction with anammox bacteria. The start-up nitrite concentration was significantly higher than the published toxic level for anammox bacteria and other lab-scale studies. The nitrogen loading rate increased from 141 to 480 mg/L/d in 120 days operation with a total nitrogen removal efficiency of 96.0±0.6%. Anammox granules with high purity were observed over the course of three months. The accommodations and proliferations of anammox bacteria in the inactive methanogenic granules might be the main reason for the high anammox purity in a short period.IV. The application of anammox process is partly limited by the availability of anammox biomass. The possibility to introduce the exotic anammox sludge to seed the reactor and fast start-up of an anammox granular reactor for treating high nitrogen concentration wastewater were confirmed in this study. High nitrogen removal was achieved for a long period. During the stable period, the NH4+-N and NO2--N removal efficiencies varied from 95%to 99.2% and from 97.7% to 100%, respectively. The Stover-Kincannon model was first applied in granular anammox process with high correlation coefficient, indicating that the granular anammox reactor in this study possessed high nitrogen removal potential of 27.8 kg/m3/d. The anammox granules in the reactor were characterized via microscope observation and fluorescence in-situ hybridization technique. Moreover, the microbial community of the granules was quantified to be composed of 91.4-92.4% anammox bacteria by real-time polymerase chain reaction.Ⅴ. The performance, inhibition and recovery processes of different types of anammox sludge, including flocculent sludge, granular sludge, and cultured inactive methanogenic granules were evaluated. Both process performance and kinetics study indicated that the reactor seeded with cultured inactive methanogenic granules possessed the highest nitrogen removal potential, followed by the granular anammox reactor and the flocculent anammox reactor. The study suggested that the concentration that as high as 988.3 mg NH4+-N/L and 484.4 mg NO2--N/L could totally inhibit granular anammox bacteria and result in a inhibition of 50% flocculent anammox activity. In addition, reactors seeded with flocculent sludge and anammox granules could be fully recovered by decreasing their influent substrate concentrations. However, the decrease of influent substrate concentration for the reactor with cultured inactive methanogenic granules could only restore about 75% of its bacterial activity. In this study, anammox bacteria purity was the major factor to evaluate the recovery ability in comparison with sludge type. Free ammonia was a more appropriate indicator for the anammox recovery process compared to free nitric acid.VI. The presence of organic matter (OM) would affect the anammox process adversely. In practice, wastewaters containing ammonium are not free from OM. In this paper, the performance of anammox granular sludge in presence of OM was first evaluated under different COD to N ratios. Low OM concentration did not affect ammonium and nitrite removal significantly but improved the total nitrogen removal via denitrifiers. High OM could suppress anammox activity, resulting in a lower ammonium removal. Nitrite removal was not affected by the existence of OM in the presence of denitrifiers. PCR test revealed that there was a reduction in the number of anammox bacteria and denitrifiers quantity increased when 400mg COD/L influent was applied. A COD threshold concentration for anammox inhibition, which was, defined when ammonium removal dropped to 80%, was 308 mg COD/L. Anammox granular sludge had higher tolerance to OM than flocculent sludge.更多还原