Seeking sustainable solutions for Nashville’s organic wastes
The Nashville metropolitan area has experienced tremendous growth in recent years and is struggling to manage its organic waste. Currently, organics (food scraps, woody waste, yard waste and some industrial waste) comprise around 32% of its residential waste and 19% of its commercial waste. The vast majority of this waste, mostly food, is sent to a landfill in nearby Rutherford County that is scheduled to close in the next five to 10 years.
In the landfill, organic waste breaks down, emitting methane, a greenhouse gas up to 80% more potent than carbon dioxide. In fact, more than 14% of the methane in the atmosphere is a result of organics decomposing in landfills.
Project partner Resource Capture has proposed using anaerobic digestion (AD), the natural process in which microorganisms break down organic materials, as an alternative technology for diverting and managing organic wastes. The AD technology has been used successfully in Europe for many years; however, it is not commonly used in North America. The research project will help to optimize the process for the Nashville metropolitan area.
The material that is left over following AD is nutrient rich and can be sustainably used as a soil amendment. One component of the project will involve designing an applied research and education program to promote economic and environmentally responsible use of the digester output on agricultural operations. In addition, researchers will identify cost-effective facility locations and estimate potential economic impacts of constructing and using anaerobic digesters to treat Nashville's food waste.
"We believe that by diverting and digesting organic waste with a project like the one proposed by Resource Capture, we can decrease demand for landfill space, reduce methane emissions and create jobs in the local community," said Christopher Clark, professor of agricultural and resource economics and project co-leader. "Additional benefits of using the compost-like material include improved soil fertility and increased farm profitability," he said.