Trends Winter 2015 - Page 5

Refuse goes in to bioreactor. Refuse tumbles in presence of air to begin decomposition. Refuse continues to spin and break down for a total of five to seven days. Materials unable to break down are crushed, reducing volume in landfill. Decomposed byproduct is filtered through screen and used as daily cover in landfill. Aging bioreactor provides landfill with many benefits O crushed inside, reducing the amount of space they take up in the landfill. The landfill’s bioreactor is formed from two sections of repurposed cement kilns that have been welded together. Ayres Associates conducted a review of the bioreactor operation as well as a structural inspection of the device to investigate the problematic areas that cause shutdowns. Recommendations from the review and inspection determined that spot welding repairs can continue to be made to keep the bioreactor running, but major, cost-prohibitive repairs would be needed to extend its life long-term. f the approximately 60 licensed landfills in Wisconsin, the Highway G Landfill is the only one still using a bioreactor, a device used to decompose refuse aerobically (with oxygen) before it is deposited in the landfill where anaerobic (without oxygen) decomposition takes place. “We use it every day when it’s not down,” said Mark Busha, landfill manager. “We use it for volume reduction.” The bioreactor, about 185 feet long and 12.5 feet in diameter, acts like a massive clothes dryer, tumbling refuse for five to seven days before the decomposed byproduct makes its way to the landfill. Busha said the “fines” produced in the bioreactor, similar to compost, are used as daily cover. Materials that don’t decompose get “It’s showing signs of fatigue,” Busha said. “Once it becomes too costly to run and the costs outweigh the benefits, it will be time to get rid of it.” – Tom Paquin TRENDS │5