COMPOSTING: Worms Experiment with Food Waste Diet

Phillip Cornish

Students are worming their way into University of California, Berkeley, dormitory kitchens to divert food waste from landfills, as part of The Berkeley Worms Compost Project. Approximately 15 Berkeley Worm members, including students and alumni, are using thermophilic traditional hot composting and worm composting or "vermicomposting" to turn food waste into valuable end-products.

Berkeley Worms currently collects and processes about 100 tons per year of pre-consumer, non-meat food waste into valuable end products. The project began in 1994 when a student-run cooperative convinced campus dorms to separate food waste from their garbage. The co-op provided free pick-up service and produced a thermophilic compost. In turn, the dorms reduced their trash hauling costs.

Nevertheless, large quantities of food waste still were being thrown away, and the thermophilic method of building hot piles and turning them every other day was too labor-intensive for the co-op to expand the program. The solution was vermicomposting, a process said to compost organics more efficiently and offer a better end-product, which can be sold to support the program.

Berkeley Worms designed a large permeable rope floor worm box based on a standard sheet of plywood's 4 feet by 8 feet dimensions. After a year of testing the prototypes, the project received $72,000 in funding from the Alameda County Waste Management Authority, San Leandro, Calif., to build 36 additional "Vermitopia Worm Vessels" and to purchase the equipment needed for food waste processing.

Berkeley Worms built its vermitopias out of 100 percent recycled wood and sealed them with recycled paint.

Pulverized food waste has more surface area, and can be processed more efficiently, so Berkeley Worms bought a food waste grinder designed specifically for vermiculture. In addition, a specialized trommel screen was purchased to harvest worms for sale to home composters and gardeners.

Since September 1997, Berkeley Worms has been vermicomposting 600 pounds of food waste per day and selling approximately 5 pounds to 10 pounds of surplus worms per week for approximately $20 per pound.

Alameda County Waste Management Authority's worm bin sales program has helped Berkeley Worms' worm sales. County residents can purchase a subsidized worm bin for home composting, but they must purchase the worms separately. Residents receive a Berkeley Worm coupon for a pound of worms with their bin purchase. The San Francisco League of Urban Gardeners (S.L.U.G.) sponsors a similar program that also benefits Berkeley Worms.

The student group also sells a variety of worm bins, including a low-budget bin made from salvaged plastic garbage cans. Berkeley Worms also offers free advice to bin buyers and vermicomposting workshops.

Berkeley Worms is seeking new pre-consumer food waste sources in a effort to expand its program to 300 tons per year while using the same number of boxes. In the past three months, it has added two campus restaurants and one off-campus housing co-op to its collection and composting program, which has increased food waste collection an average of 100 pounds a week.

The group is considering collecting the large portions of pre-consumer cooked or spoiled food from campus dining halls.

Berkeley Worms also plans to examine the feasibility of composting post-consumer food waste and soiled paper waste on a large scale using an Earth Tub in-vessel composting unit manufactured by Green Mountain Technologies, Whitingham, Vt.

The combination of castings and worm sales, along with food waste collection fees, may allow Berkeley Worms to reach its goal of self-sufficiency.

Although this small group of students are not yet self-sufficient, they have proven that their project can create and manage a composting infrastructure capable of handling all of the University of California, Berkeley's pre-consumer food waste. Furthermore, Berkeley Worms has proven that given the proper resources, small- to mid-size institutions do not need to landfill their food waste.