Geochemical Controls on Chromium Occurrence, Speciation, and Treatability

Although the occurrence of Cr(VI) in groundwater is often attributed to industrial contamination, it can also derive from natural sources, specifically the weathering of Cr-containing aquifer minerals. The release of Cr from geologic materials can lead to accumulation of Cr in infiltrating water under conditions of either natural or artificial recharge. The potential accumulation of hazardous solutes, such as Cr(VI), during groundwater recharge and storage may, in part, determine the feasibility of ASR projects. The goal of this project was to improve the science base for the management of groundwater resources subject to naturally-elevated concentrations of Cr(VI). Specific objectives included (1) assessing the influence of oxidizing conditions on the release of Cr(VI) from Cr(III)-containing minerals in laboratory experiments, (2) conducting numerical simulations to predict the potential for Cr accumulation in recovered water in aquifer storage and recover (ASR) projects, and (3) investigating redox-assisted coagulation with Fe(II) as a technology for Cr(VI) removal in laboratory experiments.