Composting is a controlled decomposition process that turns organic materials such as food waste, manure, and yard trimmings into a nutrient-rich earthy material. Compost can be used as a soil additive or as mulch (EPA 1 2022).
24% of waste in landfills is food waste and 7.2% is comprised of yard trimmings (EPA 2 2022).
During decomposition, organic waste in landfills release greenhouse gases (GHGs), methane and carbon dioxide, which trap heat in the atmosphere (EPA 2 2023). Landfills produce 15% of the U.S.’ methane emissions (EPA 2 2023).
Composting can be done in a single household and at large, commercial scales. Composting is influenced by input material, moisture, oxygen, and temperature, and can require technical skill to be done properly (EPA 3 2023, EPA 1 2022).
There are three main ways to perform large scale composting: windrow, aerated static pile, and in-vessel (Table 1; EPA 3 2023).
Table 1. Comparison of different commercial composting methods (EPA 3 2023).
Few studies investigate the profitability of commercial composting.
A voluntary survey of composting operations in the U.S. found that the number of compost programs has more than doubled since 2016 and the average size of each program has increased (Libertelli 2023).
Federal Policies. The U.S. Environmental Protection Agency Climate Pollution Reduction Grant will fund state, municipality, tribal, and territorial programs ($250 million planning, $4.6 billion implementation) to reduce GHGs, including compost programs (EPA 4 2023).
The U.S. Department of Agriculture’s Compost and Food Waste Grant has up to $9.5 million for pilot projects to plan and implement municipal compost projects.
Columbia (CO). (n.d.). Compost and Mulch Operations. City of Columbia. Retrieved April 23, 2023, from https://www.como.gov/contacts/compost-and-mulch-operations/
Kansas City Composting (KC 1). (n.d.). STA Certified COMPOST. Kansas City Composting. Retrieved April 23, 2023, from https://www.kccompost.com/compost
Kansas City Composting (KC 2). (n.d.). Curbside pick-up. Kansas City Composting. Retrieved April 23, 2023, from https://www.kccompost.com/curbside
Libertelli, C., Platt, B., & Matthews, M. (2023). (rep.). A Growing Movement: 2022 Community Composter Census. Institute for Local Self-Reliance. Retrieved April 14, 2023, from https://cdn.ilsr.org/wp-content/uploads/2023/03/A-Growing-Movement-ILSR-2022-Census-of-Community-Composters.pdf?_ga=2.239483459.1976047449.1681393398-957046353.1681144985&_gl=1*1gdo5nk*_ga*OTU3MDQ2MzUzLjE2ODExNDQ5ODU.*_ga_M3134750WM*MTY4MTQyMDIxNC41LjEuMTY4MTQyMDI1OS4wLjAuMA..
Lin, L., Shah, A., Keener, H., & Li, Y. (2019). Techno-economic analyses of solid-state anaerobic digestion and composting of yard trimmings. Waste Management, 85, 405–416. https://doi.org/10.1016/j.wasman.2018.12.037
National Conference of State Legislatures (NCSL). (2022, October 24). Fighting food waste. National Conference of State Legislatures. Retrieved April 24, 2023, from https://www.ncsl.org/agriculture-and-rural-development/fighting-food-waste
Perennial City Composting (PCC). (n.d.). Perennial city. Perennial City Composting. Retrieved April 23, 2023, from https://compost.perennial.city/
St. Louis Composting, Inc (STL). (n.d.). Compost. St. Louis Composting, Inc. Retrieved April 23, 2023, from https://store.stlcompost.com/product-category/compost/
U.S. Environmental Protection Agency (EPA 1). (2022, November 22). Composting At Home. EPA. Retrieved April 14, 2023, from https://www.epa.gov/recycle/composting-home
U.S. Environmental Protection Agency (EPA 2). (2022, December 3). National Overview: Facts and Figures on Materials, Wastes and Recycling. EPA. Retrieved April 14, 2023, from https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/national-overview-facts-and-figures-materials
U.S. Environmental Protection Agency (EPA 1). (2023, April 4). Reducing the Impact of Wasted Food by Feeding the Soil and Composting. EPA. Retrieved April 14, 2023, from https://www.epa.gov/sustainable-management-food/reducing-impact-wasted-food-feeding-soil-and-composting
U.S. Environmental Protection Agency (EPA 2). (2023, March 23). Basic Information about Landfill Gas. EPA. Retrieved April 14, 2023, from https://www.epa.gov/lmop/basic-information-about-landfill-gas
U.S. Environmental Protection Agency (EPA 3). (2023, April 3). Types of Composting and Understanding the Process. EPA. Retrieved April 14, 2023, from https://www.epa.gov/sustainable-management-food/types-composting-and-understanding-process
U.S. Environmental Protection Agency (EPA 4). (2023, April 12). Funding Opportunities and EPA Programs Related to the Food System. EPA. Retrieved April 14, 2023, from https://www.epa.gov/sustainable-management-food/funding-opportunities-and-epa-programs-related-food-system
Vergara, S. E., & Silver, W. L. (2019). Greenhouse gas emissions from Windrow composting of organic wastes: Patterns and emissions factors. Environmental Research Letters, 14(12), 124027. https://doi.org/10.1088/1748-9326/ab5262