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Formation and Release Behavior of Iron Corrosion Products under the Influence of Bacterial Communities in a Simulated Water Distribution System
Sun, H., B. Shi, D. A. Lytle, Y. Bai, AND D. Wang. Formation and Release Behavior of Iron Corrosion Products under the Influence of Bacterial Communities in a Simulated Water Distribution System. Environmental Science: Processes & Impacts. RSC Publishing, Cambridge, Uk, 16(3):576-585, (2014).
Understanding the effects of biofilm on the iron corrosion, iron release and associated corrosion by-products is critical for maintaining the water quality and the integrity of drinking water distribution system (DWDS). In this work, iron corrosion experiments under sterilized and non-sterilized condition were comparatively conducted by using both static immersion test and annular reactors (ARs). The changes of iron corrosion and iron release rates as well as the corrosion products transformation with the evolution of bacterial communities were systematically investigated. The corrosion rate was measured by weight loss method, iron release was determined by measuring the total iron concentration in bulk water and the corrosion products was characterized by X-ray diffraction (XRD). The composition of bacterial communities during different corrosion phases was characterized by using 454 pyrosequencing of 16S rRNA gene. Results showed that the corrosion rate under sterilized condition was much lower than that under non-sterilized condition after the formation of biofilm (after 7 days). However, the iron release under sterilized condition was higher than that under non-sterilized condition after 80 days. The pyrosequencing analysis indicated that the presence of sulfate reducing bacteria (SRB, e.g. Desulfovibrio, Desulfotomacufum), sulfur oxidizing bacteria (SOB, e.g. Sulfuricella and Hyphomicrobium), iron oxidizing bacteria (lOB, e.g. Acidovorax, Gal/ionella, Leptothrix and Sphaerotilus) as well as the synergistic reaction of these microorganisms could speed the iron corrosion; however, iron reducing bacteria (IRB, e.g. Bacillus, Clostridium and Pseudomonas) could inhibit iron corrosion and ironrelease significantly. Corrosion scales on iron coupons were developed as two-layered structures (the top surface layer and the inner layer) with time. The relatively stable constituents such as a-FeOOH and Fe40 3 were mainly existed in the top layers, while green rust ( Fe6(0H)12C03) was mainly existed in inner layers. The lOB (especially Acidovorax) contributed to the formation of a-FeOOH, while IRB and the anaerobic condition could be the key factors that faci litated the formation ofFe304. Biofilm and corrosion scale samples formed under different water supply conditions in a real owns verified the relationships between the bacteria composition and corrosion products.
To inform the scientific community on iron corrosion in drinking water distribution systems.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
WATER SUPPLY AND WATER RESOURCES DIVISION