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Let the “Clean Revolution” Begin!

By Don Comis
August 28, 2000

In the spirit of Earth Day, the U.S. Department of Agriculture has been involved in a project that helps keep the environment clean by composting plates and bowls discarded at a Washington, D.C., cafeteria.

The plates and bowls are made of a new biodegradable composite material, called EarthShell Packaging, that is mostly limestone and starch. EarthShell Corp. of Baltimore, Md., has supplied the products for the project since Earth Day 1999, decreasing by 24 percent the amount of solid waste sent to landfills.

Patricia Millner, a microbiologist with USDA’s Agricultural Research Service in Beltsville, Md., composted the plates, bowls, unbleached paper napkins, fiber trays and food from the U.S. Department of the Interior’s main cafeteria. As part of the project, diners threw the disposables into cans lined with EarthShell trash bags. The kitchen added food scraps, and Millner then mixed the cafeteria waste with leaves and grass clippings from the ARS research center in Beltsville.

Once or twice a week, Interior shipped the bagged garbage to Beltsville, where Millner and colleagues tested different ways of composting it. They got the quickest results with a closed container using a mixing auger.

Only small traces of the biodegradable plates, bowls and bags could be seen after four weeks. By six months, all traces were gone. Nonbiodegradable items, like plastic forks thrown into the bags by mistake, were the main identifiable remnants in the final compost. More intense composting management could speed up the decomposition of the biodegradable items.

Millner used the compost to grow cucumbers and found they did as well as those grown in commercial potting mixes.

Limestone in the dinnerware would give farmers a free soil conditioner when they apply the compost to their fields. The compost could also be used to improve soil to grow plants for wildlife habitat.

The EarthShell Corp. will continue to supply products to Interior’s cafeteria until the products are commercially available.

Scientific contact: Patricia Millner, ARS Soil Microbial Systems Laboratory, Beltsville, Md., phone, (301) 504-8163, fax, (301) 504-8370,