Type of Document	Master's Thesis
Author	Zhang, Yan
Author's Email Address	joezhang@vt.edu
URN	etd-10262005-123347
Title	Relative Effects of Water Chemistry on Aspects of Iron Corrosion
Degree	Master of Science
Department	Environmental Engineering
Advisory Committee	Advisor Name Title Edwards, Marc A. Committee Chair Dietrich, Andrea M. Committee Member Vikesland, Peter J. Committee Member
Keywords	nitrate disinfectant red water iron corrosion sulfate/ chloride ratio
Date of Defense	2005-09-13
Availability	unrestricted
Abstract The net present replacement value of all publicly and privately owned potable water pipes in the U.S. is on the order of $2.4 trillion dollars, and costs associated with deteriorating iron pipes is billions of dollars per year. Problems arising from iron corrosion include reduced lifetime of the material, scale buildup and energy loss, nonuniform corrosion and leaks, catastrophic failure, "red water," disinfectant loss and bacterial re-growth. Iron corrosion is a very complicated process and is affected by many factors. This research focused on the effect of disinfectant type, sulfate/chloride ratios, nitrate concentration, and magnesium hardness on iron corrosion. For the waters tested, chlorine better controlled red water and microbial activity in the bulk solution than chloramine. Changes in the sulfate/chloride ratio did not have a large effect on iron corrosion. High levels of nitrate increased the rate of chlorine decay as a result of free ammonia formation, and also increased the release of iron. Increased magnesium and zinc decreased the red water caused by high silicate. Microbiological activity is important in iron corrosion, and control of re-growth in water distribution systems is a major challenge for water utilities. A separate study examined the inter-relationship between iron corrosion and bacterial re-growth, with a special focus on the potential of iron pipe to serve as a source of phosphorus. Under some circumstances corroding iron and steel may serve as a source for all macronutrients necessary for bacterial re-growth including fixed carbon, fixed nitrogen and phosphorus. Conceptual models and experimental data illustrate that levels of phosphorus released from corroding iron are significant relative to that necessary to sustain high levels of biofilm bacteria. Consequently, it may be more difficult to limit re-growth on iron surfaces by limiting phosphorus in the bulk water.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    thesis.pdf 1.09 Mb 00:05:01 00:02:35 00:02:15 00:01:07 00:00:05

If you have questions or technical problems, please Contact DLA.