Rotting around the clock

Field Notes

gainesville, fla. - researchers who argue that garbage dumps are best when they're soggy and smelly - not dry like most - are working on a new concept in trash management that can digest up to 30 percent more waste.

Dubbed "bioreactor" landfills, the result could mean smaller dumps with increased capacities and the potential to turn some of it into useful material.

The secret is in the water, says John Schert, executive director of the Florida Center for Solid and Hazardous Waste Management.

Modern landfills guard against groundwater contamination by routing rainwater away from garbage and removing water that seeps out. But these steps also prevent decay, Mr. Schert says. Some landfills are so dry that it's possible to read newspapers discarded in the 1920s.

The bioreactor landfill takes the same precautions as a traditional landfill, including a double lining to prevent seepage. The major difference is the network of pipes running through it. One set of pipes takes water normally removed and pumps it back in, while another set captures the methane gas for energy purposes. The goal is to maintain a moist environment that allows bacteria to break down organic matter.

"In bioreactor technology, waste decomposes in about 2 to 5 years," Schert says. "It comes out looking like coffee grounds." This byproduct could be used for sod production or road beautification work. In addition, the method reduces the time it takes for a landfill to stabilize, meaning the land can be returned to public use more quickly.

The Florida legislature approved $3.2 million to fund the Bioreactor Landfill Demonstration Project. Project officials are now looking for a traditional landfill to use as a test site. "This is the next step in the evolution of landfills," Schert says. "We are going to use the landfill as a treatment vessel, much like a sewage treatment plant."

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