Dr. Alan Seech, Evonik’s Senior Technology Manager, will review, compare, and contrast the effectiveness of common treatment approaches for metals, metalloids, and chlorinated organics as influenced by their chemistry and site conditions.

Remediation of soil and groundwater contaminated with metals and metalloids is a significant challenge due to the substantial number of impacted sites, estimated at more than 2,000 in the United States and Europe.

Remediation of these sites can be difficult because a treatment approach that is effective for one metal may not be effective for other metals which are also present. For example, an alkaline precipitation treatment that works well for removal of hexavalent chromium could result in a higher concentration of dissolved arsenic. Successful remediation of metals-contaminated sites becomes even more difficult when both metals and chlorinated organic contaminants must be treated.

The author will briefly review the removal mechanisms for dissolved arsenic, hexavalent chromium, and divalent heavy metals with emphasis on the solubility and pH range stability of the products formed. The influence of soil and groundwater variables such as pH, redox status, and native iron and sulfate concentrations will be addressed. Representative results from bench-scale treatability testing and full-scale case studies using sustainably produced reagents including METAFIX® and GEOFORM® will be presented and discussed.