Biostimulation of Hydrocarbon Removal in a Drilling Waste-Contaminated Soil

During oil industry operations, great amounts of hazardous wastes are generated, which represent 16% of the total emissions and unloadings. Approximately 85% of the total volume is composed of three kinds of wastes, 73% drilling muds and cuttings, 5% oily muds, and 6% of heavy chlorinated hydrocarbons. These wastes are confined or spilled in soil representing an environmental concern, thus efficient technologies must be implemented to eliminate them. A study was carried out to design a successful treatability study to enhance hydrocarbon biodegradation in a clay and drilling waste-contaminated soil by the addition of nutrients and surfactant (commercial product) and an oxygen source. The studied soil had a TPH concentration of 115,000-126,000 mg/kg soil and a lightly alkaline pH (7.5). The addition of commercial product did not influence the hydrocarbon removal and could interfere with hydrocarbon analysis. Oxygen source had an important role either enhancing hydrocarbon removal and biological activities. Oxygen source concentration at 50 mg/kg allowed higher hydrocarbon removal. Bacterial growth was increased but other carbon sources could also be used. Catalase and dehydrogenase quantification were also important indicators of soil decontamination. Parameters such as nitrogen, phosphorous, pH, and moisture changed during the treatment. This is an abstract of a paper presented at the 19th Annual Conference on Soils, Sediments, and Water (10/20-23/2003, Amherst, MA).