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U.S. EPA Superfund Innovative
Technology Evaluation (SITE) Program Abstract IT's in situ photolytic and biological detoxification process is a two-step system for shallow soil contamination. The photolysis stage converts organic contaminants into more easily degradable compounds. This first step degrades the contaminants with ultraviolet (UV) radiation from either natural sunlight or artificial UV lights. The rate of photolytic degradation is several times faster with artificial UV light. Degradation is enhanced by adding surfactants to mobilize the contaminants. The second step, the biodegradation stage, further destroys the organic contaminants and detoxifies the soil. When sunlight is used, the soil is continually tilled and sprayed with a surfactant. Water may be added to maintain soil moisture. When UV lights are used, parabolic reflectors are suspended over the soil to increase the amount of UV radiation. After photolysis is complete, biodegration is enhanced by adding microorganisms and nutrients and further tilling the soil. The process destroys organics, particularly dioxins, polychlorinated biphenyls (PCBs), other polychorinated aromatics, and polyaromatic hydrocarbons (PAHs). Bench-scale tests on sandy soils contaminated with PCB and dioxin show a greater than 90 percent removal. This compares to a 30 percent removal on clayey soils, measured over a 16-hour irradiation time.
Posted July 12, 1999
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