Hazardous waste gets a microwave cleaning.

It cooks up popcorn, pizza, and Lean Cuisine in a flash. So why not use microwave heating to destroy hazardous wastes?

With hazardous waste mushrooming around the country, scientists are searching for better ways to break down its most dangerous components. Sometimes the goal is to destroy lethal mixtures, other times to recover useful materials, says Steven J. Oda, who serves on the board of the International Microwave Power Institute in Manassas, Va.

Improved microwave heating methods can break down air pollutants, degrade radioactive sludge, disinfect hospital trash, reclaim printing and dry-cleaning solvents, reactivate spent carbon, and clean up contaminated soil, Oda says.

To remove water from radioactive sludge, microwaving "means less handling of hazardous waste, minimizes risks of airborne contamination, saves time and energy, and avoids large capital and operating costs of conventional alternatives," he points out.

In Japan, new microwave methods eliminate solvents used in reprocessing nuclear fuel. In Russia, microwaves evaporate liquids from radioactive wastes, then melt the remaining solids into special glass for storage or burial. In France, scientists clean up incinerator ash with microwaves.

In the United States, old electronic circuits - in computer parts, semiconductors, and so on - have become a mounting source of hazardous waste. With microwaves, researchers can recover gold, silver, copper, and other precious metals, then melt the remainder into "durable glass frits," Oda notes.

To clean up contaminated earth, he says, microwaves will cook soil soaked with dangerous pentachlorophenols (PCPs) to 1,000*C, destroying 99.9 percent of the noxious chemicals.

"In some cases," Oda says, "microwave heating provides solutions to problems that cannot be solved effectively any other way,"