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In-situ Chemical Reduction

A number of chemical reductant’s can be used to target chlorinated solvents and certain mobile heavy metals.

Chemical reduction is the reverse of chemical oxidation with electrons transferred from the reductant to the contaminant. The result of this reaction can be the formation of benign, immobile end products e.g. Cr(VI) to Cr (III).

A number of chemical reductant’s can be used to target chlorinated solvents and certain mobile heavy metals e.g. hexavalent chrome. These include proprietary compounds, polysulfides, dithionite and Zero Valent Iron (ZVI). Of these the most commonly used is ZVI, which is typically installed as a barrier as it is difficult to inject through the subsurface. For source treatment ZVI can be introduced using in-situ soil mixing or at nano-scale.

Churngold can offer a full service including in-house laboratory studies and a selection of innovative delivery techniques to optimise effectiveness of chemical reductants. Redox (reduction/oxidation) reactions can be complex and depends on a number of conditions being right in the sub-surface. As with oxidation reactions scavenging by non-targeted substances can reduce the efficiency of the process. Thought also needs to be given to the methods of applying the chemical reductant, which can either be in powder form or suspended in a viscous carrier fluid.