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Activity of sulfur oxidizing microorganisms and impacts on concrete pipe corrosion.

机译：硫氧化微生物的活性及其对混凝土管道腐蚀的影响。

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摘要

Concrete is the foundation of modern infrastructure due to its broad availability and comparative ease of production. Rapid deterioration of concrete structures in sewage collection systems has a major impact on environmental health and safety in countries with warm climates. Using the Water Environment Federation database, the American Society of Civil Engineers (ASCE; Reston, Va.) evaluated wastewater infrastructure as poor in 2005, and cited a 2002 EPA analysis that estimated the United States will need to spend during the next 20 years nearly 390 billion to replace existing wastewater infrastructure and construct new facilities, including collection systems. The purpose of this research was to investigate the corrosion mechanism of concrete sewer pipes the major component in the deterioration of wastewater infrastructure. The practical implications of this research are improvements in the analysis and development of strategies for the prevention of concrete corrosion---strategies that will prevent the deterioration of sewer collection pipelines, saving costly replacement.; Microorganisms that produce sulfuric acid catalyze the deterioration of concrete sewer pipes in a process termed "microbially induced concrete corrosion" (MICC) [U.S.EPA, 1991]. The MICC process has been theorized to occur in the following manner:; In the first stage, chemical reactions with CO 2 and other acidic gasses in the headspace of sewers cause the pH of moisture condensing on concrete pipes to drop from 13 to about 9.; The second stage of MICC is the colonization of condensate on the pipe crown surfaces by sulfur oxidizing microorganisms (SOM), such as the neutrophilic SOM (NSOM). This population will then utilize reduced sulfur compounds such as hydrogen sulfide that are emitted from the sewage, producing elemental sulfur and polythionic acids, which further lower the pH of the concrete surface.; The third stage of concrete corrosion requires the establishment of acidophilic microorganisms (ASOM) in biofilm that grows on the sewer crown; their subsequent growth and copious acid production is the actual cause of sustained concrete corrosion. The acid front moves into the fresh concrete, reducing the pH and reacting with concrete binders, producing ettringite and gypsum, which severely compromise the imperviousness and strength of the pipe.; This research focused on improving the assessment and predictability of the MICC process. The scope included detailed study of the microbial communities associated with biogenic acid production, microbial interactions that occur in sewer pipe environments, and refining the processes that result in concrete corrosion.; Critical microbial kinetics of key sulfur-oxidizing bacteria associated with MICC were quantified for the express purpose of predicting in-situ sulfuric acid production rates. Sequenced batch reaction flasks that simulated conditions in corroding sewage collection systems were used along with a novel scanner-based image analysis method to non-destructively characterize corrosion of the concrete samples. A comparison with abiotic conditions were performed in order to validate the optical methodology and to quantify the importance of microbial activity.
机译：由于混凝土的广泛可用性和相对易生产性，混凝土是现代基础设施的基础。在气候温暖的国家，污水收集系统中混凝土结构的快速变质对环境健康和安全产生重大影响。使用水环境联合会数据库，美国土木工程师协会（ASCE；弗吉尼亚州雷斯顿）在2005年对废水基础设施进行了评估，并引用了2002年EPA的一项分析，估计美国未来20年将需要花费近3900亿美元用于替换现有的废水基础设施，并建设包括收集系统在内的新设施。这项研究的目的是研究混凝土污水管的腐蚀机理，这是造成废水基础设施恶化的主要因素。这项研究的实际意义是改进了对混凝土腐蚀预防策略的分析和开发，这些策略将防止下水道收集管道的恶化，节省昂贵的更换费用。产生硫酸的微生物在称为“微生物引起的混凝土腐蚀”（MICC）的过程中催化混凝土下水道管道的变质[U.S.EPA，1991]。理论上，MICC过程以下列方式发生：在第一阶段，下水道顶部空间与CO 2和其他酸性气体的化学反应使凝结在混凝土管道上的水分的pH值从13降至大约9。 MICC的第二阶段是通过诸如中性嗜中性SOM（NSOM）的硫氧化微生物（SOM）将冷凝物定植在管冠表面。然后，这些居民将利用污水中排放的还原性硫化合物（例如硫化氢），生成元素硫和聚亚硫磺酸，进一步降低混凝土表面的pH值。混凝土腐蚀的第三阶段需要在下水道顶部生长的生物膜中建立嗜酸性微生物（ASOM）。它们随后的生长和大量酸的产生是混凝土持续腐蚀的真正原因。酸锋进入新鲜混凝土，降低pH值并与混凝土粘合剂反应，生成钙矾石和石膏，严重损害了管道的不透性和强度。这项研究的重点是改善MICC过程的评估和可预测性。范围包括对与生物酸生产有关的微生物群落的详细研究，在下水道环境中发生的微生物相互作用以及完善导致混凝土腐蚀的过程。为了预测原位硫酸生产速率，明确了与MICC相关的关键硫氧化细菌的关键微生物动力学。模拟腐蚀污水收集系统中条件的顺序分批反应瓶与基于扫描仪的新型图像分析方法一起使用，可以无损地表征混凝土样品的腐蚀。与非生物条件进行了比较，以验证光学方法并量化微生物活性的重要性。

著录项

  • 作者

    Gutierrez-Padilla, Ma.Guadalupe Dolores.;

  • 作者单位

    University of Colorado at Boulder.;

  • 授予单位 University of Colorado at Boulder.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 224 p.
  • 总页数 224
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

  • 入库时间 2022-08-17 11:40:32

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