In Situ Remediation of Arsenic in Groundwater by Creating Biogenic Iron Sulfide Minerals via Injections
Paul Doody, Principal Engineer, Anchor QEA, LLC
A successful pilot and full-scale treatment for arsenic in groundwater was performed at a site in Florida. The technique consists of injecting degradable organic carbon (electron donor), sulfate (electron acceptor), and an iron source. Molasses was used as the carbon source, and ferrous sulfate provided both iron and sulfate. Sulfate-reducing bacteria reduce sulfate to sulfide, which combines with iron and trace elements in groundwater to form sulfide minerals. Arsenic adsorbs into the mineral surfaces and is incorporated into the mineral structures as they form. Direct geochemical, mineralogical, and spectroscopic (XANES and EXAFS) evidence from the site confirmed that arsenic sulfide phases (arsenian pyrite and realgar-like AsS) were formed in situ. After more than 2 years, groundwater in most of the wells at the site remained below pre-injection standards.
Paul Doody has more than 38 years of professional experience, most of which has been spent specializing in the management and remediation of contaminated sites. He possesses expertise in multiple facets of contaminated site management of various media (e.g., soils, sediment, groundwater, wastewater, and stormwater)—including remedial investigation and feasibility studies, treatability studies, remedial design, and remedial construction oversight. He has provided assessment, design, and engineering services related to contaminated sites throughout the world. Mr. Doody graduated with a Bachelor of Science degree in Chemical Engineering from Clarkson University in 1982. He is a registered Professional Engineer in 16 states including Florida, Connecticut, Illinois, Kentucky, Michigan, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Tennessee, Texas, Washington, West Virginia, and Wisconsin.