Full Description

Iron-sulfur geochemistry is important in many natural and engineered environments,including drinking water systems. In the anaerobic environment beneath scales of corrodingiron drinking water distribution system pipes, sulfate reducing bacteria (SRB) produce sulfidefrom naturally-occurring sulfate in the bulk water. The effect of bacterial sulfate reductionon the nature of iron corrosion scales collected from a groundwater drinking waterdistribution system having an aqueous sulfate concentration of about 100 mg/L was studied.Reduced sulfur proved to be a significant component of all iron scales studied, reaching up to22% (wt. %) in the scale. X-ray diffraction revealed the presence of elemental sulfur and FeSsub2/sub(marcasite). Other important iron minerals found were goethite ( -FeOOH) and lepidocrocite( -FeOOH). Magnetite (Fesub3/subOsub4/sub), which is believed to be an important mineral in protectingiron pipes from extensive corrosion and iron release, was not present in the iron scales. Thedominant reaction pathway operating in these scales was believed to be oxidation of HS- byFeOOH to Ssupo/sup, followed by reaction of Ssupo/sup with FeS to make FeSsub2/sub, consuming all of the FeS inthe process and leaving excess Ssupo/sup. Includes 15 references, tables, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 15File Size: 1 file , 5.6 MB