AWWA WQTC60665

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 FeS₂(marcasite). Other important iron minerals found were goethite ( -FeOOH) and lepidocrocite( -FeOOH). Magnetite (Fe₃O₄), 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 S^o, followed by reaction of S^o with FeS to make FeS₂, consuming all of the FeS inthe process and leaving excess S^o. Includes 15 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

15

File Size:

1 file , 5.6 MB