A technology akin to glassmaking is being adapted to permanently entomb several kinds of hazardous wastes.
Glassification, or vitrification, as the technology is known--from the Latin word for glass--burns off organic wastes, breaking down such poisons as dioxin into harmless water and carbon dioxide. At the same time the process seals such inorganic wastes as heavy metals into a blue-black, glassy mass, isolating them indefinitely from water, air, soil and people.
As is the surface of a drinking glass, this artificial obsidian is virtually impervious and safe even in direct contact with groundwater--the biggest threat and technical challenge of hazardous waste.
The technology has been applied to asbestos and some radioactive wastes. It is likely to be particularly effective with soil contaminated by more than one material and where digging up the soil to treat it is either an unnecessary expense or unnecessarily dangerous.
“The whole name of the game with things you can’t destroy is to immobilize them,” explained James Hansen of Geosafe Corp., a Seattle hazardous-waste cleanup company. Geosafe was formed by Battelle Pacific Northwest Laboratories to market the first commercial vitrification technique to leave the soil undisturbed. Geosafe is negotiating with the Environmental Protection Agency over cleanup projects at eight hazardous waste sites around the country. It expects to begin its first major cleanup in September.
Hazardous material is an enormous, expensive burden to thousands of U.S. businesses. Only when these wastes are deemed eliminated by the EPA and comparable state agencies--"delisted” from the federal Superfund list, for instance--can the responsible private parties be free of liability for cleanup. By law, responsible parties could include the producer or transporter of the waste, or the operator or owner of the facility where it is found, or even the owner’s lending bank.
Once-promising solutions such as burial in landfills, which can leak, may allow hazardous waste to return to haunt a company since liability remains wherever and whenever the waste shows up.
Turning the waste into glass, proponents argue, offers a long-term solution because it fundamentally transforms the waste, making delisting possible for landowners who find themselves stuck with the white elephant of a hazardous waste site. Once the land is delisted, “they can sell it,” said Geosafe’s Vincent FitzPatrick. “That’s the punch line.”
Environmentalists are reluctant to endorse emerging cleanup technologies these days, remembering all too well how some of the best-designed landfills disappointed proponents when they were found to contaminate surrounding land and water.
“There are so many gee-whiz technologies out there,” noted one longtime observer of waste-cleanup techniques. “I tend to wonder, does it make sense to turn hazardous waste into a glassy blob and just let it lie there?
But some environmentalists are more optimistic.
“Theoretically, (on-site vitrification) is a major improvement,” said David Roe, a senior attorney with the Environmental Defense Fund. “I have to be open-minded about this but somewhat more skeptical about trying to do something in and under the soil on a very large scale, where success is very hard to verify. This, after all, was the problem with landfills . . . and you just can’t dig down into 20 million cubic yards and fix it.”
But Roe agrees that one attractive feature is vitrification’s cost. An average cleanup runs about $300 to $350 a ton, according to Geosafe. This compares well to such competing methods as incineration, which runs from $300 to $2,000 a ton, not including the cost of digging it up and transporting it to the incinerator, according to Chemical Waste Management Inc., which incinerates hazardous waste.
And since in situ vitrification means treating the soil on the site, other costs can be avoided. “You can spend a lot of money trucking dirt back and forth from one site to another, which has happened a lot in California,” Roe said.
Vitrification also offers the prospect of treating combinations of wastes in one process. This can be cheaper than dealing with contaminants in stages, using more than one method.
It also promises the potential of long-term safety. Obsidian found in the American West, which Geosafe’s Hansen says is a nearly identical natural analog to vitrified waste, has been dated at 18 million years or more. And even when it reaches that age, “It doesn’t just go boink and fall apart,” he said, “It corrodes slowly away.”
Geosafe describes this as entombment for “geologic time,” using an industry phrase that points up the distinction between the stability of a glassy blob and burial in a more vulnerable, dirt-covered landfill.
“This method has good potential for this type of soil,” agrees Chaitanya Agnihotri of the EPA and a potential Geosafe client.
Agnihotri is shopping for a treatment method for a New Jersey Superfund site with a typically infernal stew of hazardous wastes--dioxins, PCBs, mercury, lead, arsenic, copper, chromium, zinc, cadmium.
As Agnihotri points out, Geosafe offers the only vitrification technology to treat his contaminated soil without disturbing it, sparing the expense and worker exposure of digging it up. This is a plus, since the EPA gives preference to technologies that treat hazardous waste in place.
In other applications of the technology, vitrification has been put to use to glassify nuclear waste in France since 1978, and in Belgium since 1985. Japan and Great Britain are building vitrification plants for nuclear wastes.
In the United States, the technology has been studied for more than a decade but is only now ready for commercial application.
West Valley Nuclear Services, a division of Westinghouse Electric Corp., plans by 1994 to begin vitrifying 600,000 gallons of high-level nuclear waste for the U.S. Energy Department and the state of New York, at the West Valley, N.Y., site of a former commercial nuclear fuel reprocessing plant.
At the Westinghouse Savannah River Co. site in South Carolina, a nuclear-weapons material production facility, construction has begun on a $938-million project that will be the world’s largest radioactive vitrification plant when it opens in 1992. Westinghouse has also developed smaller, portable units including one that can be used to “mine” landfills to make room for more waste.
At the other end of the scale, tiny Vitrifix of North America Inc., in Alexandria, W. Va., believes itself to be the only company so far to turn asbestos into safe granules of glass. In 1986, at the British navy’s Trident nuclear submarine base near Glasgow, Scotland, Vitrifix turned a half-square-mile section of an old shipwrecking yard contaminated with blue asbestos into glass gravel that was then used in the foundations of new buildings being constructed.
VITRIFICATION: TOXIC WASTE TO GLASS
1. Soil contaminated up to 30 feet deep with such waste as PCBs, dioxins and heavy metals is left in place. A layer of ground glass is spread across the surface between the electrodes to act as a starter path for the current.
2. ‘Glassification’ is done in sections, about 12 feet square. A hood and vent system draw off any escaping toxic gases as the soil is heated.
3. The electrodes are planted at four corners of the section to be melted, above. As 4 megawatts of electricity, roughly enough to run a small hotel, surge through the system, the soil is heated to 2,700 to 3,600 degrees Fahrenheit, depending on soil type. As the soil melts downward, the mass is compressed. After treatment, the blue-black glassified product can be covered with clean soil.
4. Clean soil can now be brought in to cover the glassified product. No other special materials are needed.
5. With glassification treatment completed, the land can now be used for many purposes. A golf course is one example.