| Bioremediation of chlorinated solvent source zones faces two major challenges: sustained release of electron donors at the appropriate (low) concentrations and delivery of electron donors to the intended target microbes. To address these issues, three candidate partitioning electron donors (PEDs), n-butyl acetate, 2-ethyl-1-hexanol, and isopropyl-propionate, were investigated as a long-term source of electron donor at the contaminant-water interface. A series of batch reactors and column experiments were used to determine the extent and rate of partitioning of the PEDs into the dense non-aqueous phase liquid (DNAPL), the lifetime of the PEDs in the DNAPL source zone, and the ability of the PEDs to be utilized by organohalide respiring bacteria to reduce tetrachloroethene to ethene and promote bioenhanced dissolution. Results suggest that PEDs have the potential to reduce the frequency of electron donor injections, while stimulating organohalide respiring bacteria to produce ethene in a similar timeframe to conventional electron donors. |
