COMPOSTING: Smale-Scale Vermicomposting Projects Flourish

Stephen White

What's small, reddish and eats garbage?

Earthworms, of course, and their current venue is a small, but growing area of waste reduction, vermicomposting.

Often considered to be the realm of farmers and gardeners, vermicomposting is increasingly being considered as a waste management option. As more municipalities ban yard debris from landfills, composting with redworms may become a viable alternative.

Currently, schools across the country are leading the way by using in-class vermicomposting as a tool to teach students about their environment.

In the vermicomposting process, worms recycle food waste into plant food. A classroom vermicomposting project requires an aerated container with soil and moistened newspaper for bedding. The container provides a suitable habitat for the redworms when students regularly add organic waste.

First, aerobic bacteria and other microorganisms decompose the waste. The worms then recycle these nutrients into a rich "humus," excreted as castings which can support plant growth without synthetic fertilizers.

Generally, the redworms need four or five months to convert a significant amount of waste and bedding into castings, according to Worm Digest, a quarterly newspaper which focuses on vermicomposting.

By setting up a classroom bin in the fall and burying food waste, students can observe dramatic changes in the bin. Food begins to disappear, some faster than others.

The newspaper bedding becomes unrecognizable and, if managed properly, the worm population increases allowing students to find and identify cocoons and young worms.

In addition, cafeteria food that is not consumed may be placed in large outdoor bins. With 272 students, Walterville Elementary School, Ore., vermicomposted nearly one ton of food waste over a five-month period last year, producing more than four and one half yards of castings for the school's organic garden. Previously, the food waste was landfilled.

On a larger scale, waste haulers and their municipalities have begun experimenting with earthworms to manage the waste stream's organic portion.

For example, Residuals Processing Inc., a subsidiary of Sanifill, Houston, has signed a joint venture agreement with Resource Conversion Corp. (RCC), La Jolla, Calif., to install 25 vermiconversion systems at its sites over the next decade.

Another vermicomposting proponent, Clackamas, Ore.-based Oregon Soil Corp., produces a vermicomposted soil amendment from the organic wastes of 15 local food stores. The processing takes place in an eight- by 120-foot continuous flow system where redworms convert the garbage into usable vermicastings.

Each day, the company processes between five or six tons of food scraps, more than two tons of supplements like yard trimmings or compost and approximately half a ton of paper. This method takes 21 days to make the castings.

Meanwhile, the Naturba process, developed by the French firm Sovadec, separates recyclables from organic waste, then places the organic waste in a fermentation tank, heating, disinfecting and sanatizing the matter to produce a nutrient-rich fertilizer.

In Pune, India, Uday Bhawalkar of the Bhawalkar Earthworm Research Institute, uses burrowing earthworms to process wastes such as non-toxic wastewater and sewage.

Although, for now, vermicomposting remains on the periphery of the waste industry, its popularity continues to grow. These experimental efforts may be the forebearers of larger-scaled projects.

For more information, contact Worm Digest, "Worms Deepening Our Connection To Food And Soil," P.O. Box 544, Eugene, Ore. 97440.