In-situ remediation of soil and groundwater contaminated with divalent heavy metals can be achieved by promoting the precipitation of these metals as metal sulfides, metal carbonates, or metal hydroxides. Each approach has advantages and disadvantages related to cost, solubility, and permanence (i.e., resistance to rebound) of the precipitated species. The objective of the presentation is to compare the major treatment approaches with a focus on their suitability for removal of dissolved cadmium, cobalt, copper, lead, mercury, nickel, and zinc. The mechanisms involved in conversion of these divalent heavy metals from their soluble forms to less soluble/insoluble forms during treatment with sulfide/iron sulfide, carbonate, and hydroxide-based reagents will be reviewed with emphasis on the solubility, pH range stability, mineralogy, and other characteristics of the products formed (i.e., heavy metal sulfides, carbonates, and hydroxides). The influence of soil and groundwater variables such as native concentrations of metabolizable organic carbon and sulfate, pH, and redox status will be highlighted. This webinar will include results from two in-situ groundwater remediation projects which demonstrated effective removal of dissolved cadmium, copper, lead, nickel, and zinc, with achievement of remedial objectives.

OUR PRESENTER: Alan Seech, PhD, Sr Technical Applications Manager