Chemical Fixation of Priority Heavy Metals in Soil, Sediment, and Groundwater Using MetaFix™ Reagents
High concentrations of heavy metals are found in many soil and sediment environments. At very high concentrations, heavy metals are known to create toxicity to microorganisms. Treatment approaches that rely on microbial process may not function well in an acutely toxic matrix because important processes such as carbon fermentation, oxygen consumption, and biological sulfate reduction can be significantly slowed or completely inhibited. The understanding of many metals removal mechanisms operative in soil and groundwater has advanced significantly over the past decade—thus, we are now in a better position to develop a new platform of effective metal remediation products.
Hence, in toxic environments treatment reagents that do not depend entirely on microbial activity but rather combine reduction with adsorption and precipitation of heavy metals are advantageous. MetaFixTM reagents represent an entirely new family of products for treatment of soil, sediment, industrial wastes, and groundwater contaminated with heavy metals. Treatment mechanisms based on iron, iron sulfides, and other iron-bearing minerals have significant advantages due to lower solubility and greater stability of iron-bearing mineral precipitates formed with heavy metals.
The approach used in these new reagents is to create an effective blend of reducing agents, reactive minerals, mineral activators, catalysts, pH modifiers, and adsorbents for either ex-situ or in situ applications. In situ reactive zones can be constructed to prevent migration of heavy metals in groundwater. Excavated soils or dredged spoils containing high levels of TCLP/SPLP metals can be quickly treated and stabilized before final disposal. MetaFix reagents can also be directly delivered into or onto sediments for in situ stabilization of heavy metals and thereby reduce exposure to aquatic life. Laboratory and field results showing reduction in potential leaching of key metals will be presented.
