Efforts to improve coupled in situ chemical oxidat

Authors: Nora B Sutton J Tim C Grotenhuis Alette A M Langenhoff Huub H M Rijnaarts

Publish Date: 2010/08/10

Volume: 11, Issue: 1, Pages: 129-140

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Abstract

In order to provide highly effective yet relatively inexpensive strategies for the remediation of recalcitrant organic contaminants research has focused on in situ treatment technologies Recent investigation has shown that coupling two common treatments—in situ chemical oxidation ISCO and in situ bioremediation—is not only feasible but in many cases provides more efficient and extensive cleanup of contaminated subsurfaces However the combination of aggressive chemical oxidants with delicate microbial activity requires a thorough understanding of the impact of each step on soil geochemistry biota and contaminant dynamics In an attempt to optimize coupled chemical and biological remediation investigations have focused on elucidating parameters that are necessary to successful treatment In the case of ISCO the impacts of chemical oxidant type and quantity on bacterial populations and contaminant biodegradability have been considered Similarly biostimulation that is the adjustment of redox conditions and amendment with electron donors acceptors and nutrients and bioaugmentation have been used to expedite the regeneration of biodegradation following oxidation The purpose of this review is to integrate recent results on coupled ISCO and bioremediation with the goal of identifying parameters necessary to an optimized biphasic treatment and areas that require additional focusAlthough a biphasic treatment consisting of ISCO and bioremediation is a feasible in situ remediation technology a thorough understanding of the impact of chemical oxidation on subsequent microbial activity is required Such an understanding is essential as coupled chemical and biological remediation technologies are further optimizedSubsurface and groundwater contamination of recalcitrant organic compounds has created a large industry for technologies able to clean up polluted sites The international market for the remediation sector is valued at US 50–60 billion Singh 2009 Conventional technologies focus on ex situ or onsite removal of contaminants through excavation or by socalled pumpandtreat remediation of groundwater However the high costs and health risks associated with removal of contaminated material have spurred a shift toward in situ technologies where decomposition of xenobiotic compounds via chemical or biological pathways is contained within the subsurface environment EPA 1998 Of the pool of remediation strategies in situ bioremediation and more recently in situ chemical oxidation ISCO are arguably the most commonly used in situ treatments adaptable to a variety of subsurface conditions and contaminant types

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