Abstract
Petroleum products are composed of many organic chemicals and are recognized as the most prevalent contaminants found in contaminated soils and sediments. Of particular regulatory interest are simple aromatics and polycyclic aromatic hydrocarbons, which are toxic and carcinogenic at low levels. Many treatment processes have been used for treatment of fuels. Biotreatment appears to hold the most promise as a cost-effective process that can destroy petroleum hydrocarbons on site. The potential for bioremediation was evaluated on a soil contaminated with heavy motor oil from years of dumping waste oils from an automotive garage. This soil was selected because it posed a unique challenge to bioremediation and therefore provided the framework for evaluation of various process enhancements. A series of shake-flask experiments (500-mL flasks filled with 25 percent w/w water-soil slurries) was performed to determine the extent and rate of removal of total petroleum hydrocarbons (TPH) using various soil amendments, including nutrients, cometabolites, a nonionic surfactant, and microbial seeds. The information from the shake-flask experiments was used to plan a series of experiments that used eight 30-L (8-gal), bench-scale biocell reactors. The results of the biocell experiments show that approximately 80 percent of the TPH could be removed using a treatment system that consisted of nutrient and surfactant amending with bioaugmentation with activated sludge.
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