Inoculating Bacteria into Polycyclic Aromatic Hydrocarbon-Contaminated Oil Sands Soil by Means of Electrokinetics

Abstract

Electrokinetics (EK) is commonly used in bioremediation studies to aid mobilization of amendments in low permeable soils. This study evaluated the possibility of using EK as a delivery mechanism to emplace organic contaminant degrading bacteria, Sphingomonas paucimobilis EPA505 and Mycobacterium vanbaalenii PYR-1, into low permeability soils without disturbing the soils. Bacterial cultures were grown to exponential phase with a polycyclic aromatic hydrocarbon (PAH) carbon source, and then transferred to EK reservoirs. Direct current was applied to induce EK movement, and soil DNA evaluated for the inoculated bacteria. Electroosmotic transport efficacy for a silty and an oil sands soil was compared. Results show that EK can be used to inoculate S. paucimobilis EPA505 into soils under electroosmotic flow, but the hydrophobic nature of soils especially enabled electroosmosis. For the first time, we demonstrate that in situ inoculation of non-native bacterial species using EK is possible. The results of this study demonstrate the potential for future applications of this technique for in situ bioaugmentation and remediation of PAH-contaminated soils.