Interest in Water Oxidation Begins to Broaden
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Municipal sewage treatment plants, such as this one in Harlingen, Texas, can use supercritical water
oxidation technology to turn organic sludges into water and carbon dioxide. |
The same technology being developed to destroy toxic military wastes can also be used for more
benign wastes
Additional members are expected to join a consortium supporting a supercritical water oxidation (SCWO)
R&D project now under way at the Massachusetts Institute of Technology's (MIT) Corrosion
Laboratory.
The project is designed to investigate corrosion control and alloy performance in aggressive SCWO
environments. Consortium members include several producers of nickel alloys, namely Haynes International,
Krupp VDM and Special Metals, as well as the U.S. Army and the The Nickel Development Institute (NiDI). The
project is directed by Professor R. M. Latinison.
Test programs and full-size pioneer SCWO plants in the U.S., Europe and Japan are already bringing this emerging technology to commercial readiness (Nickel, June 2001). SCWO holds considerable promise as a process for destroying a broad range of wastes in an environmentally safe manner.
Phase one of the two-phase MIT project focuses on investigating the corrosion behaviour of a range of nickel alloys by means of instrumented tube sections, and also the potential of corrosion mitigation through feed stream modification. Phase two will add titanium to the test matrix and concentrate on monitoring/controlling feed-stream optimization by means of in-situ electrodes.
The test environment, in both phases, will consist of chlorinated solvents over a broad range of temperature and pH (measure of hydrogen ion concentration). Gerard Sorell, a NiDI consultant covering innovative waste destruction technologies, is monitoring the project for the institute.
The achievements and challenges in commercializing SCWO for destroying wastes were highlighted at an international conference/workshop held in Arlington, Virginia in August 2001. The meeting was co-sponsored by the U.S. Army and private-sector organizations, including most SCWO developers and users from the U.S., Europe and the Far East.
Considerable progress was made in the broadening applications for SCWO, not only for the destruction of highly toxic wastes but also for less aggressive industrial and municipal sludges. A major challenge is indentifying cost-effective materials for highly corrosive wastes containing chlorine, fluorine, sulphur, phosphorus and nitrogen species (at times in combination). Such wastes are encountered in the destruction of certain military wastes that require the use of expendable platinum linings.
The corrosion workshop gave a chance to learn more about the MIT research project and the key role played by NiDI. Also, potential new members of the consortium expressed interest in the work.
Photo: HYDROPROCESSING LLC
