With over 15 years of chemical amendment addition experience by industry-leading design engineers, ARS uses a wide range of materials/chemicals when designing remediation options involving chemical oxidation.
ARS’ Design Engineers will select the chemical and an activator as needed based on site specific factors, including the target contaminants, lithology, and hydrogeology. Equally as important to the proper chemical solutions is the injection protocol that will ensure contact between the chemical oxidant and the contaminant. ARS’ real field experience and proprietary injection techniques are the reason we achieve successful remediation designs on nearly every project in which we are involved.
In Situ Chemical Oxidation (CHEMOX or ISCO)
Chemical oxidation (ISCO) has emerged as a cost-effective and viable remediation technology for the treatment of VOCs (e.g. PCE, TCE, and 1,4-Dioxane) and petroleum-based contaminants (e.g. BTEX) in groundwater, soils, and sediments. The most common oxidants ARS has experience with are permanganate and persulfate. Both have been widely used in the past few years since they are relatively inexpensive and have a long history of safe and successful use.
In Situ Chemical Reduction (ISCR)
In situ chemical reduction (ISCR) involves the emplacement of a reductant to degrading toxic organic compounds, immobilizing metals such as Cr (VI) by adsorption or precipitation, and degrading non-metallic oxyanions such as nitrate. As already mentioned, zero valent iron (ZVI) is the most commonly used reductant, and has remediate halogenated ethenes and ethanes, energetics compounds, Chromium (VI), Arsenic, and Uranium. [ITRC 2011]. Other reductants that are used to address metals include ferrous iron, sodium dithionite, sulfide salts (calcium polysulfide), and hydrogen sulfide.
Combined Chemical and Biological Reduction
ARS has combined various carbon sources with ZVI to provide accelerated COCs transformation using reductive processes, both biotic and abiotic. Emulsified Vegetable Oil (EVO) combined with ZVI provides a long lasting terminal electron sources to promote biological activity and promotes abiotic reduction for greater than five years. ARS has found this formulation of EZVI/carbon is:
- easier to inject
- results in greater radius of distribution
- efficient and cost-effective