A University of Illinois engineering professor has been 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.
“When a landfill dries out, the waste degrades so slowly it can take decades for the area to stabilise and become safe for other uses. Such nonperforming landfills are called 'dry tombs’,” explained Krishna Reddy, professor of civil and materials engineering at UIC.
As an alternative, bioreactor landfills have emerged to counter those conditions. In bioreactor landfills, leachate recirculation systems increase moisture and accelerate degradation. The performance of bioreactor landfills results from coupled hydro-bio-mechanical processes. However, according to Reddy the industry lacks a comprehensive, holistic mathematical model that considers and effectively analyses these coupled processes in landfills.
“Landfills are eyesores,” continued Reddy, “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?''
To engineer landfills that can do all this, the UIC said that 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 biogas gas.
According to the university, 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.
UIC noted that 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 optimising existing ones. He and his group take a multidisciplinary approach, including geo-environmental engineering, sustainable engineering, biology and computational mechanics.
According to Reddy, landfills are 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 concluded.
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