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题名: 给水管网生物膜细菌群落对管网腐蚀、 腐蚀产物转化及其释放的影响
作者: 孙慧芳
学位类别: 博士
答辩日期: 2014
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 王东升
关键词: 给水管网 ; Drinking water distribution systems(DWDS) ; 生物膜 ; biofilm ; 细菌群落 ; bacterial community ; 管垢特征 ; corrosion scale characteristics ; 水源切换 ; source water switch ; 铁释放 ; iron release
其他题名: Effect of biofilm bacterial community on iron corrosion, corrosion product transformation and release in drinking water distribution system
中文摘要:       给水管网内壁普遍存在着生物膜。管壁生物膜不仅会直接导致输配过程微生物相关的水质指标下降,还对管网腐蚀、腐蚀产物结构特征及其释放行为有重要影响。本文首先对实际供水管网中不同水源水质条件下所形成的管壁生物膜群落结构做了系统表征,对腐蚀相关的细菌进行了识别;采用静态烧杯试验和生物膜动态反应器研究探讨了管壁微生物的生长与群落结构变化对铸铁试片腐蚀速率、腐蚀产物的转化与释放的影响;利用管段反应器和管网中试系统,对具有不同管垢特征的实际供水管道进行模拟水源切换实验,探讨了SO42-对管网铁的释放、管壁生物群落和管垢特征的影响以及调节进水溶解氧(DO)、消毒剂种类及浓度、碱度和pH控制管网铁释放的作用效果。取得了如下主要结果:    实际管网生物膜调查与表征发现,与通地表水源和混合水源的管壁生物膜相比,通地下水源的生物膜具有相对较低的生物丰度和多样性。Proteobacteria是管壁生物膜最主要的生物群落(相对含量约为40% ~ 97%),并且在通地下水的样品中含量相对较高;Firmicutes在通地表水(28% ~ 35%)生物膜样品中的相对含量显著高于通地下水(0.5% ~ 2.88%)样品中的含量(p < 0.01)。统计结果显示Proteobacteria和Firmicutes分别与水的碱度和CODMn呈显著正相关。管壁生物膜中的铁还原菌(IRB,)和铁氧化菌(IOB)在通地表水的管网生物膜的相对含量(IRB 17.85% ~ 22.98%;IOB,0.44% ~ 3.36%)远远高于通地下生物膜中的含量(IRB 0.25% ~ 2.08%;IOB,0.13% ~ 0.09%)。    静态和动态的小试研究发现,硫酸盐还原菌(SRB, Desulfovibrio 和Desulfotomaculum)、硫氧化菌(SOB, Sulfuricella)和IOB(Acidovorax, Gallionella, Leptothrix 和 Sphaerotilus)的生长和协同作用能够加速铸铁腐蚀和铁释放;而IRB则能在一定程度上抑制铸铁腐蚀和铁释放。铁腐蚀产物随时间出现分层现象,α-FeOOH和Fe3O4 主要存在于腐蚀产物的外层中,Fe6(OH)12CO3主要存在于内层中。结合对实际管网中管垢和生物膜的分析,研究发现IOB(尤其是Acidovorax)的生长能够促进管网中α-FeOOH的形成,IRB和水固界面的缺氧环境则促进了Fe3O4的形成。 管网模拟实验表明,SO42-浓度增加后,系统铁释放量均有所升高,且金属元素Mn、As、Cr、Cu 和 Ni的释放量也有所增加。管网内壁腐蚀产物特征对管网铁释放有重要的影响。长期通地表水和混合水源的管垢较为发达,具有致密硬壳层(主要成分为较为稳定的Fe3O4和α-FeOOH),对SO42-具有较好的耐受性。长期通地下水的管垢层薄且稳定性差,铁的释放受SO42-影响较大。XRD结果显示,水源切换之后管垢中较为稳定的Fe3O4的相对含量有所增加,而FeCO3、β-FeOOH和γ-FeOOH等不稳定铁氧化物的含量有所下降,管垢逐渐趋于成熟,管网水质也逐渐趋于稳定。 生物群落结构在不同类型的管垢中(硬壳层、实心垢、多孔疏松层和薄腐蚀层)具有明显差异。IRB和IOB主要存在于硬壳层和实心垢中,SRB和SOB主要存在于多孔疏松层中。硝酸盐还原菌(NRB)在所有管垢中的含量相差不大。进水SO42-浓度增加后,管垢中NRB和IOB的相对含量呈下降趋势;SRB、SOB和IRB的含量则相对增加。SRB和SOB的增加会加速管网腐蚀和铁释放,IRB则会促进Fe3O4的产生,形成致密层而抑制铁的释放。因而,管网内的铁释放行为取决于占优势的细菌群落。 适当调节进水DO(8 ~ 15 mg/L)、余氯浓度和碱度(130 ~ 250 mg/L),可在一定程度上抑制管网铁释放;增加进水氯胺浓度(1.3 ~ 2.0 mg/L)则会加速铁释放。这些水质参数的调节不仅直接影响管网内铁的腐蚀及其释放相关的化学反应,也通过对生物膜中细菌群落结构的改变影响铁的释放。此外,不同通水历史条件下所形成的管垢差异特征也会影响上述水质指标对铁释放的控制作用。因此,在实际的水源频繁切换实施时,应综合考虑不同的水质化学特性、不同通水历史的管垢特征、管网水力分布等因素,制定合理的水质恶化控制措施。
英文摘要:       Biofilm is commonly found on the inner wall of water distribution systems. Micro organisms in biofilm could not only cause biological water quality deterioration, but also affect iron corrosion rate, the formation/transformation and release behavior of iron corrosion products. In this work, biofilms developed under different source water histories in drinking water distribution systems (DWDS) were collected and systematically investigated using 454 pyrosequencing of 16S rRNA gene, some potential corrosive bacteria were also analysed. To understand the mechanisms involved in the corrosion of iron pipe and the formation and release of corrosion scales, iron corrosion experiments under sterilized and non-sterilized conditions were comparatively conducted by using both a static immersion test and bacterial annular reactors (BAR), Experimental pipe section reactors and pilot-scale pipe loops were setup with in-use unlined cast iron pipes to simulate the scenario of source water switch. The effect of SO42- on iron release. the composition of bacterial community and corrosion scales was elucidated, and the iron release control performance by dissolved oxygen (DO), disinfectant (residual chlorine and chloramine), alkalinity, and pH was explored. The following conclusions could be reached: The characterization and analysis of biofilms in actual DWDS showed that the biofilms formed in DWDS transporting groundwater (GW) had the lowest level of bacterial diversity, indicating a greater biostability of GW than surface water (SW). Proteobacteria (in the range of 40%-97%) was the predominant group in all biofilm samples, but was relatively higher in biofilms under GW condition. The relative abundance of Firmicutes in biofilms with SW (28%-35%) was significantly (p < 0.01) higher than that in biofilms with GW (28%-35%). Statistical analysis revealed that Proteobacteria and Firmicutes were positively correlated with alkalinity and chemical oxygen demand (COD), respectively. The abundance of sequences affiliated to iron reducing bacteria (IRB) and iron oxidizing bacteria (IOB) were relatively higher in biofilms with SW(IRB 17.85% ~ 22.98%; IOB,0.44% ~ 3.36%) than that with GW (IRB 0.25% ~ 2.08%; IOB,0.13% ~ 0.09%). Results of iron corrosion experiments with static immersion test and BAR showed that the formation and transformation of corrosion products and bacterial community are closely related to each other. The presence and interaction of sulfate-reducing bacteria (SRB, e.g. Desulfovibrio and Desulfotomaculum), sulfur-oxidizing bacteria (SOB, e.g. Sulfuricella) and IOB (e.g. Acidovorax, Gallionella, Leptothrix and Sphaerotilus) in biofilm could speed iron corrosion; however, IRB (e.g. Bacillus, Clostridium and Pseudomonas) could inhibit iron corrosion and iron release. Corrosion scales on iron coupons could develop into two-layered structure (top layer and inner layer) with time. The relatively stable constituents, such as goethite (α-FeOOH) and magnetite (Fe3O4) mainly existed in the top layers, while green rust (Fe6(OH)12CO3) mainly existed in the inner layers. The study found that IOB (especially Acidovorax) contributed to the formation of α-FeOOH, while IRB and the anaerobic condition could facilitate the formation of Fe3O4. Experiments of the simulated DWDS found that with the increase of sulfate concentration, the iron release as well as Mn, As, Cr, Cu and Ni were all increased. The characteristics of corrosion scales had significant effect on iron release. The corrosion scales on pipes transporting SW and blended water were thick-layered corrosion scales and possessed much higher stability due to the larger proportion of stable constituents (mainly Fe3O4 and α-FeOOH). Instead, the rather thin and uniform non-layered corrosion scales on GW history pipes contained larger proportion of less stable iron oxides. Under high sulfate condition, the iron release was much more serious in the pipes transporting GW than that in the p
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35198
Appears in Collections:环境水质学国家重点实验室_学位论文

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孙慧芳. 给水管网生物膜细菌群落对管网腐蚀、 腐蚀产物转化及其释放的影响[D]. 北京. 中国科学院研究生院. 2014.
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