Efforts to improve coupled in situ chemical oxidation with bioremediation: a review of optimization strategies

Abstract

Purpose 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 focus. Conclusions and recommendations Although 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 optimized.

Oxidant selection to treat an aged PAH contaminated soil by in situ chemical oxidation

“…With permanganate, PAH degradation ratio was positively correlated to oxidant dosage; however the main drawback of permanganate is the formation of manganese dioxide that can strongly affect soil permeability and possibility of further vegetation [17]. In comparison, O 2 release and faster reaction with Fenton's reagent and activated persulfate are more favorable to bioremediation and soil construction [38].…”

“…Also, persulfate have been proved to affect biological parameters, e.g. inhibition of the soil microbial community [38] and low dosage should be chosen. This is also important to avoid the dissemination of sulfate in soil and groundwater.…”

“…However, in many situations of aged soil remediation, a very high PAH removal rate is not directly attained with oxidation and a post-treatment by bioremediation is performed to achieve clean-up objectives [8,[36][37][38].…”

Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

“…The drastic decrease in ORP thereafter can be explained by the biodegradation of products of partial oxidation of contaminants, which are known to accumulate during chemical oxidation of hydrocarbons in soil [13]. Although persulfate and other oxidants inhibit and kill some microorganisms, chemical oxidation and biodegradation are compatible [27]. Ndjou'ou et al [21] demonstrated that aerobic biodegradation thrived almost immediately after chemical oxidation was complete in soils, and that the two processes even co-existed at low oxidant doses.…”

Effects of ozonation on soil organic matter of contaminated soil containing residual oil

“…Studies have shown that ozone effectively removed polycyclic aromatic hydrocarbons (PAHs) (Rivas 2006), polychlorinated biphenyls (Javorska et al 2009), diesel fuel (Yu et al 2007), and residual oil following long-term biodegradation (Liang et al 2009). Ozonation is also an effective pre-treatment that enhances the subsequent biodegradation step by reducing the toxicity of the contaminants, producing more biodegradable intermediates, and/or improving the bioavailability of the parent compounds (Goi and Trapido 2004;Liang et al 2009;Nam and Kukor 2000;Sutton et al 2011).…”