Strategies for Enhancing Bioremediation for Hydrocarbon-Impacted Soils

Abstract

Abstract Bioremediation has been successfully used to treat crude-oil impacted soils within a reasonable timeframe at petroleum sites in Indonesia (typically 2-6 months). In a collaborative effort between PT. Chevron Pacific Indonesia, Chevron Environmental Technology Company, and Institute of Technology, Bandung (ITB) in Indonesia, laboratory studies were conducted to test the impact of adding amendments such as chemical oxidants and surfactants to enhance the rate of bioremediation of crude-oil impacted soils. Partial chemical oxidation of hydrocarbons may result in by-products that are more susceptible to biodegradation. Consequently, it was hypothesized that addition of low levels of oxidants could potentially enhance the rate of subsequent biodegradation of hydrocarbons in crude-oil impacted soils. Chemical oxidants tested in studies in ITB and in Chevron laboratories included hydrogen peroxide, sodium percarbonate, calcium peroxide, carbamide peroxide and ammonium persulfate. In contrast to chemical oxidants, addition of surfactants could potentially enhance the bioavailability of hydrocarbons or alter soil characteristics (e.g., hydrophobicity), thereby enhancing the rate of bioremediation in crude oil impacted soils. Surfactants that were tested included Tergitol NP-10 and Tween-80. In general, the addition of oxidants (solid or liquid) and/or surfactants tested in these studies did not impact the extent of TPH biodegradation over the long-term compared to biostimulation controls (nutrients + tilling). However, addition of small amounts of surfactants can help reduce the lag time before TPH biodegradation commences, and thereby achieve remedial goals (of 1% TPH) within a shorter timeframe. This could significantly increase throughput at a bioremediation facility for a small incremental cost.