Sequential Chemical Oxidation and Aerobic Biodegradation of Equivalent Carbon Number-Based Hydrocarbon Fractions in Jet Fuel

Abstract

Remediation of petroleum mixtures is complicated by the differing environmental degradabilities of hundreds of individual hydrocarbons in the mixtures. By grouping the individual hydrocarbons into a few fractions based on equivalent carbon number (EC), the present study examined the chemical and biological degradation of the fractions. With or without prechemical oxidation (25 days) by three oxidants (KMnO4, H202, MgO2), sterile and live microcosms were constituted with aquifer samples for aerobic biodegradation (134 days) of JP-4 jet fuel. Eighty-seven hydrocarbons were recovered and grouped into nine EC fractions. The apparent removal and actual transformation rate constants were estimated for both chemical and biological degradations. The data show that prechemical oxidations facilitated removal of total petroleum hydrocarbons (TPH) (up to 80%) within shorter times (<50 days) than biological alone. KMnO4 and H202 were better oxidants in terms of mass reduction in shorter times yet to some extent inhibited the subsequent microbial activity. MgO2 was a moderate oxidant with less inhibition of microbial activity. Selective degradation of the EC fractions was observed for both chemical and biological processes. The biological processes were much less effective than the prechemical oxidations in transforming aromatic fractions, the more toxic fractions. The favorable substrates (i.e., aliphatic EC approximately 10) for microbial growth were also those most subject to chemical oxidation. The results suggest that for remediation of petroleum contaminants, sequential chemical and biological technologies may surpass biological alone and more moderate oxidants such as MgO2 may be better candidates. More work is needed on the optimal dose and residence time for applied oxidants and on the application to engineering design and formulation of cleanup standards.

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

“…This result was explained by the fact that pre-oxidation with persulfate showed a minimal impact on the 2,4-DNT-degrading portion of the microbial population, both in terms of number of degraders and the time required for bacterial degradation to rebound. In experiments where permanganate, Fenton's reagent, or an oxygen-release compound containing MgO 2 were paired with bioremediation on jet fuel contaminated soil, similar results were found (Xie and Barcelona 2003). Permanganate was the oxidant that showed the highest mass reduction, but did not provide the greatest overall remediation efficiency.…”

“…Many batch experiments with ISCO have been performed in a phosphate buffer, which simultaneously controls the pH and provides phosphate to microbes Liang et al 2009;Valderrama et al 2009). Ammonium may be added for analytical reasons ), or in conjunction with ample trace metals, minerals, and vitamins to create optimal conditions for biomass growth (Sahl et al 2007;Xie and Barcelona 2003). In experiments in which ammonium and phosphate were either added to or absent from microcosms with fuel oil-spiked samples, TPH removal was 6-14% higher when nutrients were present (Tsai et al 2009a).…”

“…In lab experiments where microcosms were autoclaved prior to ISCO to ensure that all contaminant removal could be attributed to chemical oxidation, it was clear that reinoculation was required to regenerate bioremediation (Xie and Barcelona 2003). The impact of bioaugmentation has been less conclusive in other studies testing this as a variable in coupled chemical and biological remediation.…”

“…As summarized in Table 1, chemical oxidation can create adverse environments in terms of pH and oxidation potential that inhibit general microbial growth and function. Recent work has indicated that the type Kulik et al 2006;Xie and Barcelona 2003) and quantity (Buyuksonmez et al 1999;Jung et al 2005;Palmroth et al 2006a;Sahl et al 2007;Valderrama et al 2009) of chemical treatment have repercussions on soil geochemistry and bacterial populations and thus on the success of continued bioremediation. Additionally, the ISCO step oxidizes a specific fraction of the contamination, producing a range of oxidized substrates.…”

Diesel degradation in soil by fenton process

“…1 The extraction, handling, transportation and storage of such a volume of material often result in spills, which can cause water and soil contamination. 2,3 In Brazil, one of the most serious reported environmental accidents involving oil derivatives occurred in Guanabara Bay in January 2000, when approximately 1.3 million liters of crude oil were spilled.…”