In recent years, increasing numbers of consumers have become interested in making sure the food system is more sustainable. However, the bulk of effort and attention has gone toward the part of the food system that leads up to their forks. Much less attention has been paid to the “post-fork” part of our food system. This part of the food system is big. In 2008, food losses were estimated to be 30% at the retail and consumer levels in the U.S., with a total estimated retail value of $165.6 billion (Buzby and Hyman 2012). Other estimates are similar, ranging from 25–40%.
What happens to this food?
An estimated 1 million tons of food is landfilled in Washington State annually (WA Ecology 2010a), contributing to greenhouse gas (GHG) emissions and many other environmental concerns. Diverting and composting Washington State’s food scraps would reduce GHG emissions by 872,695 MT CO2e annually, representing 1.8% of Washington State’s target emissions reduction by 2050 (U.S. EPA 2011).
Ongoing efforts make our state a leader in diverting food scraps from landfills. Many residents of Seattle and King County can have their food scraps “recycled” along with yard waste into saleable compost. And, in total, the state has 60 organic wastes recycling programs, as many as California, and many more than other states (Yepsen 2013). This is a major improvement over landfilling and a great learning tool for other communities that are eager to begin their own organic recycling systems.
Unfortunately, composting food scraps has not been without its own set of challenges. Because of the time lag between residential disposal, collection, and transport food waste has often already begun to decompose (and smell) before it arrives at the compost facility. Once it arrives, high moisture content and the composition of food scraps can inhibit the composting process, contributing to odors and lowering compost quality. And lastly, the overwhelming success of residential food scrap diversion has in some cases overloaded the capacity of existing composting facilities.
What can we do?
While there are no easy answers, ongoing research at CSANR suggests that these problems can be addressed. First of all, ongoing efforts to reduce the amount of waste generated per person, will continue to be important. However, especially as populations continue to grow, improving processing of organic wastes will also be critical. Upgrades to infrastructure at composting facilities, such as air filtration systems, are one such strategy. Changing the size of piles, improving aeration, and other strategies that optimize the biological conditions for composting are also important. These odor reduction strategies are described in a recent literature review carried out by CSANR researchers in partnership with the Washington Department of Ecology.
In the longer term, incorporating newly emerging technologies, such as anaerobic digestion and pyrolysis, may represent the “next generation” of organics recycling. Anaerobic digestion creates an anaerobic environment (without oxygen) in which naturally occurring microorganisms convert complex organic materials (such as food wastes) to biogas, a source of renewable energy. Pyrolysis, a thermal technology more suited for woody wastes, can produce a combination of either heat or fuel and biochar, a charcoal product.
Researchers at CSANR have recently proposed a “biorefinery concept” to guide integration of these new technologies with existing composting facilities in the Pacific Northwest. This biorefinery could provide greater environmental benefits, more effective treatment of organics wastes, and renewable energy. As researchers and others seek to address technical challenges and make this system economical, the concept will undoubtedly need to adapt. However, we hope that it provides a guiding vision for improving the sustainability of organic waste management.