Vermicomposting: Making worms work for you | Food Feature | Indy Week
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Vermicomposting: Making worms work for you 

Click for larger image • The worms produce nutrient-rich droppings used to fertilize flower beds.

Photo by Jeremy M. Lange

Click for larger image • The worms produce nutrient-rich droppings used to fertilize flower beds.

The kitchen prep line at the legislative cafeteria in Raleigh generates about 40 pounds of food scraps a day. At most restaurants and home kitchens in America, scraps like those wind up in landfills, buried under piles of nonbiodegradable materials, fermenting and producing greenhouse gases and polluting water supplies. Nationally, about 12 percent of landfill mass is food, which amounts to about 800,000 pounds a year in North Carolina alone.

But the eatery in the state house is a model for food waste disposal: In addition to shipping uneaten food off to hungry people and sending garbage to a contractor that composts, the legislative building cafeteria has a state-of-the-art container out back—insulated and equipped with its own heating system. What's inside is rather ancient, however, having crawled the earth for millions of years.

Click for larger image • Organic recycling specialist Brian Rosa shows off the vermicomposting facility behind the Legislative Building. About 50,000 worms digest and recycle non-meat food waste. - PHOTO BY JEREMY M. LANGE

While the legislature debates the minutiae of tax reform, about 50,000 worms go about their own business, digesting the parts of the greens that didn't make it to the salad bar, among other kitchen discards.

"I knew absolutely nothing about this process until we got involved in it," says Tony Goldman, director of the administrative division, which oversees food services at the legislative building. "It's really kind of amazing to see how they can reduce this waste to almost nothing."

Well, not quite nothing. Goldman explains that food waste is mostly water, and once that is extracted, buckets of food are reduced to mere handfuls. But what's in those handfuls is equally important: worm castings, aka invertebrate poop. It looks a lot like soil, and is coveted by gardeners for its high nutrient content.

The legislative building started its project in August; soon, workers there will harvest the castings and feed them to the facility's many plants.

Partnering with the microscopic bacteria and fungi that aid in the breakdown of vegetation, worms take traditional composting practices up a notch. They speed up the process of creating fertile humus (plant food), picking up where the microbes leave off.

Vermicomposting, as it's known, is gaining popularity for its efficiency and ease of use. The worms do their own aerating (no turning the pile needed), and given the right moist, dark environment, the worms digest biodegradable garbage in a small space, with little effort and no odors. Small-scale setups require little more than a lidded container and shredded paper for bedding.

Composting uses worms known as red worms or wigglers. (Larger nightcrawlers or earthworms don't like the captive life and don't eat much organic matter anyway.) These worm species are highly adaptable to the conditions found in most worm bins. Thin and only a few inches long, the 50,000 worms at the statehouse weigh only about 50 pounds.

The Abundance Foundation will host a workshop on vermicomposting at Piedmont Biofuels in Chatham County on April 5. Participants will take home a bag of worms and a bin, ready to start adding food scraps. (See below for details.)

The Triangle is also a central meeting spot for wormers nationwide. N.C. State University will host the eighth annual national Earthworm Farming Conference May 19-20 in Raleigh.

The state's organic recycling specialist, Brian Rosa, teaches the workshops. He works for the division of pollution prevention and environmental assistance, part of the N.C. Department of Environment and Natural Resources.

His main goal, accomplished through public education and performing waste audits for industry, is to divert food waste from landfills.

About 6 percent of the state's food waste goes somewhere more productive than landfills, Rosa says. That may not seem all that impressive, but the national average is only 3 percent.

A lot of the food that's diverted from landfills comes from meals captured by food banks that otherwise would be thrown away. North Carolina, Rosa explains, has aligned its priorities with the U.S. Environmental Protection Agency's standards: Unused food should first be fed to hungry people, then animals, and when those needs are met, composted. Landfills are a last resort.

After a waste audit at the legislative building, 60 percent of the food waste began to be diverted from the landfill. Each month, 12,000 pounds goes to the Interfaith Food Shuttle. Another 200 to 300 pounds of post-consumer food waste from the cafeteria gets picked up by a local composting contractor every day. That's in addition to the 40 pounds of prep line waste the worms process each day.

But it's not just unused food for human consumption that would otherwise be thrown away. Industry creates a huge amount of food waste, as well. Think of all those peels that were once on the potatoes now in that bag of chips, or the shells from eggs used in ice cream.

A lot of these pulps and byproducts cannot be put in landfills because their water weight makes disposing of them that way cost-prohibitive, and landfills are not designed to take water anyway. For years, companies simply have spread these food wastes back on open land, which worked all right until certain nutrient levels got too high and out of balance.

Running out of options, companies call Rosa. He sends them details of the five commercial composting facilities in the state, three of which are in Wake County. One of the companies, Brooks Contractors, even has pioneered a curbside pickup service for food waste—the first of its kind in the country.

Although none of those companies is using worms, vermicomposting has big potential for large, dirty jobs.

Rosa has spent the last several years consulting on a project at the Puerto Rico Zoo to design worm bins to process 300 pounds of elephant dung a day. The zoo is going to start with 300 pounds of worms and 50 pounds of worm cocoons, and within months, the worm population will double. Rosa says if it works as planned, the zoo plans a similar system for giraffe waste.

Worms are already being used to digest livestock manure here in North Carolina. A hog farm in Robins, just west of Fayetteville, has enough worm bins to process 8,000 pounds of hog waste per day.

Given that North Carolina is the nation's second-largest pork producer, the possibilities of using worms to compost the manure—currently an environmental debacle—are vast.

"The implications for a lot of things are phenomenal," Rosa says.

Learn more about worms

Vermicomposting workshop:
April 5, 10 a.m. to 2 p.m.
Piedmont Biofuels Industrial Plant, Pittsboro
Registration required:, 545-2558

Books (available from
Worms Eat My Garbage by Mary Appelhof
Recycle with Earthworms by Shelley C. Grossman & Toby Weitzel
The Worm Book by Loren Nancarrow & Janet Hogan Taylor

On the Web:
N.C. Division of Pollution Prevention and Environmental Assistance:
N.C. Cooperative Extension Service:

To buy worms:


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