MHI will be using SRI's technology to destroy polychlorinated biphenyls (PCBs) in large volumes. Conventionally, these hazardous wastes are disposed by incineration—a relatively expensive process that can release harmful dioxins and other chemicals into the air and suffers from widespread public disfavor. SRI and Mitsubishi have been collaborating to commercially advance AHO since 1995 and continue to develop and improve the technology

SRI Overcomes Cost and Corrosion Barriers

SRI's AHO oxidation technology uses a unique variation of supercritical water oxidation, an approach that has been ardently pursued as an alternative to incinerators for the disposal of hazardous waste and military ordinance for more than fifteen years. However, corrosion of such disposal units from acidic gases and salt deposits had prevented the widespread commercial or military adoption of such an approach, as measures to address the corrosion problem resulted in prohibitively expensive designs.

SRI's patented innovation exploits the special properties of pressurized, superheated liquid water ("supercritical" water) to decompose the hazardous wastes to undetectable amounts. This process is augmented by adding nontoxic sodium carbonate: an inexpensive, readily available catalyst/reagent. This enhancement to the technology eliminates corrosion and accelerates oxidation rates within the reaction chamber such that smaller and less-expensive units may be constructed. Additionally, the SRI design is constructed from inexpensive materials and operates at a lower temperature than conventional supercritical water oxidation processes. The SRI AHO design also offers significantly lower operating costs compared to current incineration methods.

Mitsubishi Heavy Industries Successfully Demonstrates SRI's Solution

Mitsubishi Heavy Industries has successfully demonstrated in a pilot plant SRI's proprietary AHO technology for the destruction of PCBs. By heating PCBs in water to 380 degrees centigrade at 270 atmospheres and introducing certain inexpensive catalysts, harmful chlorine was recovered as sodium chloride (common table salt) and organic carbon was converted to carbon dioxide and water.

MHI will use the technology in commercial plants to decompose very large volumes of PCBs in concentrated form and in solution with other materials such as transformer oil. MHI's current designs reduce these substances to concentrations of three parts per billion at greater than 99.9999% removal efficiency. Designs for future plants are expected achieve detection limits of 0.5 parts per billion in the near future. MHI also anticipates lower overall operating costs, as the SRI system uses easily obtainable parts and consumes less electricity than do conventional waste disposal methods.

About SRI International

Silicon Valley-based SRI International is one of the world's largest independent research, technology development and consulting organizations. Founded in 1946 as the Stanford Research Institute, SRI has been meeting the needs of strategic, global markets for more than 50 years. As part of its strategy to bring its technologies to the marketplace, SRI licenses technologies, forms strategic technology partnerships and creates spin-off companies.

Technical inquiries may be directed to Indira Jayaweera, Principal Research Chemist of the Hydrothermal Research Program, at indira.jayaweera@sri.com or (650) 859-4042. For information regarding the SRI Hydrothermal Technology Licensing Program, please contact Scott Taper, Manager of Technology Commercialization and Business Development, at staper@unix.sri.com or (650) 859-3512.

Visit SRI on the web at http://www.sri.com/