May 1994

Modified Retorting for Waste

(pdf file, 4470K)

In the early 1980s, we began developing an oil-shale retorting process that uses hot solids as the heat carrier. This technology, called the hot-recycled- solid (HRS) retorting process, is now being modified and extended for application to important problems in the field of waste treatment and environmental cleanup. Current studies at the LLNL HRS pilot plant and at a related facility at Sandia National Laboratories≠California are showing that the modified HRS process is suitable for removing organic compounds and for decomposing sodium nitrate (NaNO 3 ), both of which are constituents of the mixed waste stored in underground tanks at the Hanford, Washington, facility. Our small-scale pilot system uses 50 kg of hot ceramic spheres fed into a reactor to provide a large surface area for the thermal treatment and decomposition of sodium nitrate. This approach has many advantages over other technologies: it incorporates excellent safety features, is environmentally benign, and avoids sticking and agglomeration of liquid waste, which can be a problem with other approaches. Through collaborative studies, we are exploring several additional potential applications of our HRS retorting process, including the destruction of high explosives and liquid gun propellant as well as the decomposition or treatment of many of the other harmful chemicals and compounds found throughout and beyond the DOE complex.

Cleaning Up Underground Contaminants

(pdf file, 674K)

Beneath hundreds of industrial and government sites across the United States, pools of such contaminants as hydrocarbon fuels, cleaning solvents, and industrial chemicals threaten drinking water supplies. In a fairly typical example of this problem, between 1952 and 1979, tens of thousands of liters of gasoline leaked from an underground tank at a former LLNL filling station. Researchers from LLNL and from the University of California at Berkeley used a unique technology -- dynamic underground stripping -- to rapidly remove some 29,000 liters of gasoline in less than a year. This technology applies heat -- by steam and electricity -- to vaporize trapped contaminants in the soil. Once vaporized, the contaminants are removed by vacuum extraction. These processes are monitored and guided by underground imaging. Dynamic underground stripping is relatively inexpensive and promises to be the cleanup technology of choice at numerous sites in the future.

May 1994 in PDF format

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