Number 224 (Story #2), May 1, 1995 by Phillip F. Schewe and Ben Stein|
MAN-MADE LIGHTNING BOLTS FOR BREAKING DOWN AND MONITORING WASTE , described by Dan Cohn of MIT and colleagues at the APS meeting, represent a potential near- term spinoff of long-term nuclear fusion research. In a pilot-scale research furnace at MIT, a 10,000-degree plasma, created by passing an electric current between a pair of graphite electrodes in a nitrogen-filled gas chamber, has been used to melt waste material (consisting of soil, metals, combustible materials and sludges) into a lavalike liquid. The liquid solidifies into a stable black glass which can be safely stored or even used as a construction material. The process produces no toxic ash, virtually no dioxin, and less gas emission than traditional incineration techniques. Furthermore, it has the potential of being more economical than present techniques. In a separate demonstration at the Hanford Waste Reservation in Washington, room- temperature electron plasmas selectively acted upon minute concentrations of hazardous carbon tetrachloride molecules vacuum-pumped from waste deposits and split them into less stable compounds that were eventually broken down into carbon dioxide, table salt, water, and some carbon monoxide. Paul Woskov of MIT described a system that determines the hard-to-measure temperatures at the center of a furnace by detecting the high-frequency microwaves that cut through the smoke in the furnace. David Rhee of MIT discussed a real-time system that continuously monitors heavy metal emissions in a waste-burning process. The system uses microwaves to create a high-temperature plasma in the waste gas. The plasma excites the heavy metals and causes them to emit radiation which reveals their spectroscopic fingerprints; concentrations as low as 1 ppb can be detected.