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Lightening the Load at Landfills?

Scientists are breathing new life into old idea for making bacteria degrade landfill waste--without oxygen and thus odors. In the 1960s, researchers first tested the idea of putting anerobic bacteria to work on industrial waste water. Although the bacteria would successfully break down the organic waste for a period of time, the process always petered out. Now scientists know that the bacteria weren't getting the nutrients they needed to keep on living. And based on the results of a recent year-long pilot project at the Lycoming County landfill in Pennsylvania, they know that anerobic bacteria might help solve the landfill problem after all.

At Lycoming, some 1,000 tons of trash are dumped each day into the landfill, which is more than 20 years-old and rises some 200 feet above the road. Within 11 years, there will be no more room for trash. So Thomas DiStefano at Bucknell University--working with his former mentor, Richard Speece at Vanderbilt University--installed series of toaster-sized bioreactors to test the potential anerobic bacteria might have to lighten the landfill's load. Recycled water in one reactor converted the garbage into simple organic acids. These in turn were pumped into a second reactor, where the bacteria converted them into methane gas--which can be used to produce electricity. A residue from the reaction works well as a soil nutrient, they say.

Looking at the initial data, DiStefano estimates that a full-scale anerobic operation applied to food wastes alone--which account for up to 10 percent of the garbage dumped at Lycoming--would generate some 88 million cubic feet of methane and 2,600 tons of soil nutrient each year. Ultimately, he hopes the bioreactors could convert from 50 to 70 percent of all the organic waste now being buried. The county commissioners were sufficiently convinced to extend his contract for another two years. "This is cutting edge," Speece says, "and it is a privilege to be associated with something that probably 10 years down the line will be commonplace."

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