A food waste digester has the power to transform food waste into two incredible products, renewable energy and biofertilizer. Anaerobic digestion is the biological process that decomposes organic materials in the absence of oxygen. Microorganisms break down the organic matter into biogas, a mixture of methane and carbon dioxide. But that’s not all, digesters produce another valuable creation, a nutrient-rich byproduct known as digestate. Anaerobic digestion typically takes place in sealed containers called digesters, where controlled conditions optimize the decomposition process. By effectively diverting organic waste from the clutches of landfills, digesters reduce methane emissions and relieve pressure on waste management infrastructure.

The first step in the process of turning food waste into energy and biofertilizer is to blend the mixture into a smoothie-like mixture before an automatic system feeds this consistently to the digester. Inside, the microorganisms inside of the digester break down the organic matter and convert the feedstock into two products, renewable biogas and biofertilizer. The versatile biogas output holds so many possibilities. It can be converted into heating homes and powering businesses. That’s not to mention how converting biogas to compressed natural and renewable electricity can fuel vehicles revolutionizing the transportation sector. The nutrient rich biofertilizer created supports plant growth and healthy soil in agriculture, enriching the land while promoting regenerative agriculture.

Learn more about how biodigester systems work.

Small-scale food digesters

Smaller-scale solutions like Chomp’s are built for communities of 500 - 100K people in urban or rural settings since they are compact and odor-free. With the power to be delivered and operational within six months, speed and convenience are at the forefront. Chomp offers two different digester systems: the Core and the Mini. We take pride in the Core, our flagship product line able to process 185 to 4,500 tons per year. The Mini manages 25 to 175 tons per year providing an option for smaller organizations to make a difference too. Chomp uses an advanced system to eliminate odor at each step of the digestion process. Since the digesters are found at the source of organic waste, the conventional hauling and disposal hassle of this waste dissapears. The nature of this on-site operation means that noise, traffic, and pollution are not an issue.

Chomp’s digesters repurpose diverse organic materials into something new. This includes kitchen trim, post-consumer dining room food scraps, meat, grease, oil, all edible liquids, seafood, dairy products, starch, sugar, fruits, vegetables, small bones, soiled paper products, napkins, paper towels, waxed paper, lightweight wood tableware (stir sticks, toothpicks, spoons, knives, forks), fats, fryer oil, grease trap waste, beverages, alcohol, soup, condiments, eggshells, glycerin, grass clippings, leaves, small sticks, and other yard waste.
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Food waste digester case study

Chomp's Anaerobic Digester located at Island Spring Organics on Vashon Island

We are witnessing a wave of inspiring success stories as more organizations turn to anaerobic digestion in pursuit of lessening their carbon footprint and advancing their sustainable efforts. One such company is Island Spring Organics, a tofu factory on Vashon Island that manages their organic waste with one of Chomp’s on-site anaerobic digesters. Their organic waste finds its purpose, as they harness the biogas created from the tofu waste to use as heat in their factory and the biofertilizer created is distributed among farms on the island resulting in astonishing crop yields that surpass those achieved with conventional, petrochemical fertilizers in the community. This process not only addresses the waste management challenges faced by Island Spring Organics but also supports a local circular economy. 

Learn more about the financial and environmental benefits of anaerobic digestion. 

How to run a successful food waste digester?

To run a successful distributed food waste digester, follow these essential steps to reach the full potential of anaerobic digestion: 

1. Secure the Right Location: It is important that your location has access to water and electricity, as well as sufficient ground space, for deploying the system. Chomp’s digesters can easily fit into urban settings. The smallest unit Chomp manufactures requires 240 ft² while the largest requires 13,750 ft².
2. Secure Supply of Organic Waste: The anaerobic digestion system is designed for regular volumes but can handle fluctuations or peaks in quantity or consistency of the available organic waste supply without compromising its operational efficiency. A supply of organic material is necessary, but it can be generally infrequent. There is flexibility since the unit has equipment to regulate the waste stream to manage variations in organic waste supply by feeding a controlled amount of organic material to the anaerobic digester at a specific rate.
3. Plan a Beneficial Use for Biogas Energy: There are many potential uses for the energy including building heating, water heating, electricity, combined heat and power, cooking gas, and propane substitute. Additionally, the energy can be converted into renewable electricity for powering electric vehicles or processed into compressed natural gas for vehicle fuel.
4. Develop a Beneficial Use Plan for Biofertilizer: The biofertilizer can be used on site or sold within the community for use with plants or farm crops. Nutrient-rich biofertilizer can be used for seed treatment, soil application, root dripping and drenching, and as a foliar spray.
5. Secure Funding: Plan how you will fund the capital expense or equipment lease of the anaerobic digester. There is an upfront capital cost accompanied by an eventual return on investment. Tax incentives provide opportunities to reduce the cost of anaerobic digestion by up to 30-60% like the Investment Tax Credit (IRC § 48), the Energy Production Tax Credit (IRC § 45), the Electricity Production Tax Credit (IRC § 45), and the Accelerated Depreciation Deductions. Carbon credits represent measurable, verifiable emission reductions achieved through certified climate action projects. After an initial assessment, projects can be registered in the standard’s registry for carbon credit eligibility. There are also various federal grants available from the EPA and USDA to aid in funding anaerobic digestion lowering the cost.
6. Decide on Ongoing Operation: Determine who will be responsible for operating the digester on an ongoing basis. Chomp’s digesters are designed to be easy to operate, with relatively few moving parts. Operating a unit does not require a significant full-time commitment. For example, the Chomp’s smallest unit requires 4 labor hours per week whereas the largest requires 68 labor hours per week. Certain parts of the system do require some inspection and maintenance to ensure proper functionality. Chomp provides operating and maintenance manuals and can assist with managing the operations in addition to training support.