Designing Landfills That Clean Themselves

Landfill Professor Reddy

”Landfills are eyesores, but they’re unavoidable,” says engineering professor Krishna Reddy.

A UIC engineering professor is designing state-of-the-art landfills that will really stand out from those that are just — well, dumps.

“Landfills are eyesores,” said Krishna Reddy, professor of civil and materials engineering. “But they’re unavoidable. Even with the best waste management — prevention and recycling — we still will have waste that has to be disposed of.

“We don’t want to create these indestructible pyramids, and have future generations look at them and think, ‘what the heck have they done?’”

When a landfill dries out, the waste degrades so slowly it can take decades for the area to stabilize and become safe for other uses. Such nonperforming landfills are called “dry tombs,” Reddy explained. He was awarded a three-year, $280,000 grant from the National Science Foundation to develop a model to transform dry tomb landfills into efficient waste treatment systems.

Reddy and his students want to make landfills that perform their own in-ground treatment, produce gas to recapture energy, allow the recovery of usable materials and re-stabilize themselves for eventual reuse. To engineer landfills that can do all this, Reddy must find the best way to capture the moisture that naturally leaches out and recycle it back in, along with helpful bacteria that break down the organic waste into energy-rich burnable gas.

Once the organic waste has decomposed and the landfill is stable, operators can mine the inorganic waste for valuable metals like iron, copper and aluminum. The controlled but rapid transformation of the landfill will make it easier to plan for the site’s eventual reuse.

Reddy has years of field data and experimental results that he and his colleagues will study to find effective ways to support these recovery processes. His goal is to create a tool for designing stable and effective engineered landfills or for optimizing existing ones. He and his group take a multidisciplinary approach, including geo-environmental engineering, sustainable engineering, biology and computational mechanics.

The field, he says, is ripe for change. “Operators and regulators of landfills are interested in improving, but the current leachate-recycling programs are not designed on a rational basis,” he said.