Food scraps from Portland businesses are taken to an anaerobic digestion facility, where they are blended into a liquid and then broken down by bacteria. The bacteria create methane, which is captured and burned to make electricity.
Portland’s business and residential compost are different
The compost collected in Portland’s residential curbside program goes to a different processing facility than the compost collected by businesses, which is one reason there are different guidelines for what is allowed in residential compost and business compost.
The food scraps collected in Portland’s commercial compost program go to different processing facilities, including an anaerobic digestion facility.
How anaerobic digestion works: Food waste is blended into a liquid and is broken down by bacteria. The bacteria create methane, which is captured and burned to make electricity.
What goes in: Food is the only thing allowed in business compost: It's what the bacteria want to eat! Other materials gum up the system and have to be filtered out. (Learn more and download a poster.)
The end product is energy for homes and businesses, as well as fertilizer to enrich soils.
How do food scraps turn into energy?
This 1-minute video shows how an anaerobic digestion facility turns food waste into energy.
(Video created by the British recycling campaign, RecycleNow.)
The food scraps and yard debris collected in Portland’s residential curbside compost program go to a commercial compost facility.
How it works: At commercial compost facilities, compost is laid out in big rows that are regularly mixed, or “turned.” These rows function like a bigger, hotter version of a backyard compost bin.
What goes in: Food is the key ingredient. It’s what provides the nutrients that farmers and gardeners need for healthy crops. Some non-food items are also allowed: yard debris, paper towels and napkins, and pizza boxes (Learn more or download a guide). These non-food items help provide a balanced mix of fiber, and wet and dry materials.
The end product is nutrient-rich compost that farmers, gardeners and vineyards add to their soil to help grow food and other plants.