A Review of Composting as a Local Food Waste Solution

By: Anna Ramgren and Dodi Allocca

In the United States, 31-40% of food is wasted (Neff, Spiker, and Truant 2015, 1). Wasting food also wastes the resources used in agriculture, which includes “35% of freshwater consumption, 31% of cropland . . . and 21% of post-recycling municipal solid waste” (Neff, Spiker, and Truant 2015, 2). Citing the negative environmental, social, and economic impacts of food waste, the USDA and the EPA declared the nation’s first food waste reduction goals in 2015 (USDA 2015; Smith 2015). The EPA (2015) cites composting as a practice that diverts large amounts of food waste from landfills, curbs methane emissions, and reduces the need for fertilizers. Composting at the municipal level can reduce consumer waste, which accounts for a majority of food waste (Neff, Spiker, Truant 2015). This review will discuss methods for measuring food waste, examine case studies of municipal composting, and outline uses for municipal compost products to assess how municipal composting can mitigate food waste. This literature review shows that food waste systems, municipal waste compost programs, and uses of municipal waste compost are context specific. Therefore, these components must be evaluated by any town or city considering to implement a municipal composting program.

Understanding dynamics of food waste is critical to designing apt food waste diversion strategies. A study of food waste in upstate New York provides a methodology for assessing a “community food waste stream,” using a systems approach. This study estimated the quantities of food waste produced from many sources by combining local data on food waste mass and national averages (Griffin et al. 2009, 70). This system-wide food waste assessment method can inform case specific policies to reduce food waste.

A study of food waste on the Mississippi Gulf Coast (Evans-Cowley and Arroyo-Rodríguez 2013) quantified sources of food waste using methodology similar to that of Griffin et. al. (2009), but also incorporated a stakeholder analysis. Integrating stakeholder analysis and quantitative food waste assessment allowed the authors to outline goals and recommend actions which included the creation of a municipal compost program (Evans-Cowley and Arroyo-Rodríguez 2013). Utilizing both quantitative analysis and stakeholder analysis allows for the holistic design of municipal waste compost systems fitted to local social and physical dynamics. These studies provide methodologies that can be applied to other localities.

In recent years, some cities and towns have implemented municipal waste compost programs. New York City provides curbside collection of organics for over one million people (Rueb 2017). New York City processes organic waste through anaerobic digestion, which produces biogas. While the city plans to use biogas produced by the compost to meet growing energy needs, more uses for municipal compost product are needed (Rueb 2017). Towns and cities within the province of Alberta, Canada have many different municipal compost programs (Paddison and Chaw 2000, 48). In their study of Alberta’s municipal composting programs, Paddison and Chaw (2000) conclude that the market and demand for compost product needs to expand to ensure the longevity of composting programs in the area (48). Despite differences in scale and compost product, these two case studies suggest that finding innovative uses for compost product is critical to the continuation of municipal composting programs. As these municipal compost programs mature, holistic studies should be conducted to contribute to general knowledge of municipal compost systems.

Once municipalities produce compost, it needs to be used or sold. Turning compost regularly can increase biologically available nitrogen, which improves its quality and therefore its value (Hargreaves et al. 2007, 7). Municipal compost product can benefit agricultural soils by increasing availability of nutrients, decreasing erosion, and increasing water holding capacity (Farrell and Jones 2009, 4306-4307). Compost product could also be used to remediate polluted sites (Farrell and Jones 2009, 4307-4308). Composting processes generate heat, which could be used to heat water or buildings, but this use has not been studied extensively (Sjoberg 2015; Rueb 2017). More research should be conducted to generate further creative applications of municipal compost product. As there are several possible uses for municipal compost product, towns and cities should determine the most cost-effective and environmentally sound applications for their particular context.

Addressing food waste through municipal composting is a place-based endeavor.  Food waste dynamics, program specifics, and appropriate uses for municipal compost product depend on location. However, regardless of location, similar methods can be used to evaluate food waste quantity and stakeholder values, lessons about challenges can be drawn from existing programs, and possible uses of municipal compost product remain constant. A framework which draws on these collective lessons could be used to assess composting in different areas. Such a framework would be a useful tool to help cities and towns design efficient municipal composting programs.

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