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Composting
Food Waste
Composting offers the benefits of resource efficiency as well as creating an incredibly beneficial product from organic waste that would otherwise have been landfilled. Composting can be done both on-site and off-site. Available land space, as well as haulers and end users in your area will help you decide which is better for you. If you compost on-site, you will need a supply of both carbon (e.g. newspaper, cardboard, wood chips) and nitrogen (e.g. food scraps). Off-site composters can collect from a variety of generators, allowing businesses to send only food scraps to the site.
Whether done onsite or offsite composting can take many forms. Among the many factors that determine the best composting method to use in a particular situation are the space available, the types of material available for compost, and the quantity of material.
Composting on-site
If resources and space permit, generators can compost food scraps onsite using in-vessel composting technology. In-vessel composting systems can compost waste volumes from a few pounds to more than 60 tons a day. Compostable materials are placed in the container and mixed, shredded, and aerated by the system. Some in-vessel systems are fully automated with sensors to monitor temperature, oxygen, and moisture. They use biofilters to reduce or eliminate odors. This is a good method for institutions with large amounts of compostable materials and limited space.
There are several questions to consider when planning a large-scale, onsite food composting program. Do you…
- Have enough space?
- Have staff resources to separate food from trash and/or to operate equipment?
- Have the appropriate infrastructure (i.e., electrical, sewer backup) for the type of technology you want to use?
- Have an end use for the finished compost?
- Have nearby business’ or residential neighbors’ support and cooperation?
- Have or need approval from your local enforcement agency? Please see Do I need a permit? on the Frequent Questions page.
In-vessel Composting
“In-vessel” composting is actually a piece or pieces of equipment are enclosed, temperature and moisture controlled systems. Organic materials are fed into a drum, silo, concrete-lined trench, or similar equipment where the environmental conditions—including temperature, moisture, and aeration—are closely controlled. The apparatus usually has a mechanism to turn or agitate the material for proper aeration. They come in a variety of sizes and capacity, and have some type of mechanical mixing or aerating system. In-vessel composting can process large amounts of waste without taking up as much space as the windrow method. In addition, it can accommodate virtually any type of organic waste (e.g., meat, animal manure, biosolids, food scraps). Some in-vessel composters can fit into a school or restaurant kitchen while others can be as large as a school bus to accommodate large food processing plants. In-vessel composting can be used year-round in virtually any climate because the internal environment is carefully controlled, often by electronic means. This method can even be used in extremely cold weather if the equipment is insulated or the processing takes place indoors.
Conversion of organic material to compost can take as little as a few weeks. Once the compost comes out of the vessel, however, it still requires a few more weeks or months for the microbial activity to stabilize into finished compost.
Aerated Windrow/Pile Composting
Shredded organic materials (food waste, yard trimmings, wood chips, etc) are formed into rows or long piles and aerated either passively or mechanically. This method can accommodate large quantities of organic materials. It cannot accommodate large amounts of meat or grease without frequent turning and careful temperature and moisture control.
Unaerated Static Pile Composting
Organic discards are piled and mixed with bulking material. This method is best suited for small operations; it cannot accommodate meat or grease.
Vermicomposting
Worms (usually red worms) break down organic materials into high-value compost (worm castings). This method is faster than windrow or in-vessel composting and produces a high-quality compost. Animal products or grease cannot be composted using this method.
For more information on the various types of composting technologies, please visit EPA’s Composting website.
