Predictions of Biotreatability and Actual Results: Soils with Petroleum Hydrocarbons

Abstract

The hypothesis evaluated was that the extent to which a contaminated soil undergoes weathering prior to treatment affects the degree of chemical loss that occurs during bioremediation. The hypothesis was evaluated using soils from field sites. Nine soils from petroleum and related industry sites were obtained and characterized for chemical composition. The chemical characterization data were used to identify the extent of prior weathering of hydrocarbons in the soils. Based on such a weathering evaluation, the potential for further chemical loss in a bioremediation process was predicted. Those predictions were then compared with the results of biotreatability studies. Shake flask and solid-phase biotreatability studies were conducted on the soils to determine the rate and extent of hydrocarbon loss in the soils due to bioremediation. The predictions of biodegradation potential agreed well with the actual biotreatability results for seven of the nine soils used in the evaluation. These included both soils (A, E, and I) in which there was significant chemical loss during the biotreatability studies and soils (B, C, F, and J) that did not experience significant chemical loss during the biotreatability studies. Soil K had a moderate decrease in chemical concentrations during bioremediation, whereas no decrease was predicted. The results from this study indicated that it is possible to make screening level judgments about the hydrocarbon loss that may occur due to bioremediation based on simple hydrocarbon characterization information. The results also indicated that hydrocarbon composition and weathering should be considered before initiating bioremediation projects.