RICHLAND PILOT PROJECT TESTS RUBBER RECYCLING TECHNOLOGY RICHLAND -- Rubber recycling. It's something that car and truck owners long for each time they pay a fee to dispose of their old tires. And it's way to prevent those giant tire piles we occasionally see burning out of control on the national television news. The Rubbercycle, new technology under development at the U.S. Department of Energy's Pacific Northwest National Laboratory in Richland, could make rubber recycling much more common and reduce the problems associated with used tire rubber. Currently, there are more than one billion waste tires stockpiled in the U.S., with 250 million tires added annually. Approximately 900 million tires are located in municipal solid waste landfills. Most landfills are becoming increasingly reluctant to accept this problem waste stream. Waste tires stored in above-ground stockpiles pose major risks in terms of fires and the resulting toxic smoke. There are additional potential health problems because rainwater caught in the tires provides excellent breeding grounds for mosquitos and the diseases they can carry. Estimates predict that less than one-half of the waste tires generated annually will be recycled in 1996. At that rate, recycling won't make a dent in used tire stockpiles. "Basically we're using microorganisms to break-down the rubber so that it can more easily be recycled," said Bob Romine Pacific Northwest project manager. "It's currently difficult to get ground tire rubber to combine well with virgin rubber, so recycling of rubber is very low." But Pacific Northwest's process uses sulfur-loving microorganisms to change the chemical nature of sulfur-cross links in the rubber, without damaging the carbon backbone of the rubber molecules. The microbes, isolated from hot springs in Yellowstone National Park, help create chemically reactive sites on the surface of finely ground tire rubber which, in turn, allows formation of chemical bonds between the used rubber and virgin rubber. Laboratory experiments show that new tires could be composed of up to 15 percent recycled rubber with no deterioration in physical properties. A pilot plant scale bioreactor system, capable of processing 400 pounds of rubber per day, is under construction at Pacific Northwest. The laboratory is beginning work with a major rubber recycling company, Rouse Rubber Industries, Inc., to test this technology on a larger scale. The pilot plant will be shipped to Vickburg, Miss., for a field demonstration at Rouse Rubber Industries, Inc. this fall. If the technology is adopted by the rubber industry, it could affect drivers everywhere. When vehicle owners replace your tires, the tire dealer tacks on a "tipping fee" or charge of about $3-$4 to cover the cost of disposing of the old tires. Using the microbial processing to make rubber recycling feasible on a large scale would increase the market for waste tire rubber which, in turn, would likely eliminate the tipping fee. In fact, in the future, consumers may be paid for recycling their old tires instead of paying to have them hauled away to a landfill.