The effect of solvent concentration on the use of palladized-iron for the step-wise dechlorination of polychlorinated biphenyls in soil extracts.

This report describes the application of palladized iron (Pd/Fe) to the dechlorination of polychlorinted biphenyls (PCBs) at ambient temperature. Experiments supported by congener-specific analyses demonstrated that dechlorination occurs in a step-wise fashion with the meta-chlorines being more reactive than ortho-chlorines. Over the course of the laboratory experiments, complete conversion to biphenyl was observed. The process was also tested with PCBs dissolved in high (40-60%) concentrations of ethanol and isopropanol as a means of simulating solutions generated by commercial soil and solid waste extraction processes. The reaction rate was sensitive to the percentage of solvent but complete dechlorination was still indicated. Tests with soil extracts from a contaminated site demonstrated that there were no apparent interferences from asphalt and other miscellaneous debris. Short-duration tests with highly contaminated PCB solutions from a hazardous waste site demonstrated efficient dechlorination although there was a reduction in reaction rate with time.

Bioremediation of petroleum hydrocarbons in soil column lysimeters from Kwajalein island.

Soil column studies were used to evaluate petroleum hydrocarbon (PHC) remediation in soils from Kwajalein Atoll. Treatments included controls, and combinations of water, air, nutrients, and bioaugmentation with indigenous microbes (W, A, N, and M, respectively). Microbial colony forming units (CFU) decreased in the control columns and in treatments without air. Treatments including W+A+N and W+A+N+ exhibited increased CFU. One third of the PHC was removed by water and another third was removed by W+A+N and W+A+N+M treatments. Bioaugmentation with indigenous PHC degraders did not enhance bioremediation. Potential for bioremediation was demonstrated by air, water, and nutrient amendments.