Snapshots of Selected Large-Scale

Vermicomposting Operations

North Carolina Cooperative Extension Service

Rhonda Sherman-Huntoon

Extension Solid Waste Specialist

Biological & Agricultural Engineering Department

Box 7625, Raleigh, NC  27695-7625

Phone: (919) 515-6770      Fax: (919) 515-6772

E-mail: sherman@unity.ncsu.edu

URL: http://www.bae.ncsu.edu/people/faculty/sherman

No. 1 - April 1997 (revised 6/97)

PLEASE NOTE:

Grace McKellar Centre, Geelong, Victoria, Australia

About 13 cubic yards per week of kitchen scraps, shredded paper, and garden trimmings are vermicomposted in open-air beds at this hospital. Zeolite and soil are mixed in for pH and odor control, and weeper hoses in the beds provide moisture. Current landfill tipping fee cost savings are $4,000 per year (local tipping fees are $6/cy). Projected savings are $14,000 per year when capacity is reached at three times the current amount being processed.

Green Cross Society of Bombay, India

To curb the vermin population in Bombay, this non-profit organization has set up several projects to convert organics into vermicompost. For example, a smaller-scale operation vermicomposts 4 tons of slaughter house waste per day. A larger operation, which vermicomposts 20 tons of vegetable waste per day, has been set up in Kalyan, north of Bombay, in collaboration with the Bombay Municipal Corporation.

Hobart City Council, Tasmania, Australia

Worms digest about 66 cubic yards of municipal biosolids per week, along with green mulch. Zeolite mixed in with the feedstocks helps balance the pH and absorb ammonia and odors. About two-thirds of this volume becomes vermicompost, which is sold to the public on site. They plan to expand the operation to process 330 cubic yards per week. The City of Hobart is currently saving $56,000 per year from avoided landfill tipping fees, and they are receiving an equal amount of revenue from their sales of vermicompost.

Indian Aluminum Co. Ltd, Belgaum, India

Since July 1995, vermicomposting has been used to process garbage and sewage from 500 homes. Compostable garbage is processed in seven concrete vermicomposting bins (one for each day of the week) measuring 7 x 20 meters. Sewage is fed to a 200 square meter "vermifilter"--a biofilter with a 30 cubic meter deep bed of vermicompost which contains earthworms and a root zone of selected plants. The vermifilter can process up to 100 cubic meters of sewage per day, and the purified water is used to irrigate gardens. This low-labor system needs little operation and maintenance. This is one of six large-scale vermicomposting projects developed by Bhawalkar Earthworm Research Institute that have motivated about 5,000 farmers in 16 Indian states to vermicompost their organic materials.

National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, United States

In late 1996, NIEHS purchased two heated worm composting units, called Worm Wigwams, and 10 pounds of worms. Shredded confidential office paper and finely shredded wood rejected for animal bedding for NIEHS's labs is used for bedding. Staff volunteers take turns bringing 10 to 20 pounds of food scraps each day from the cafeteria to the worm bins, located outdoors, near the facility. Employees use the worm castings as a soil conditioner for their plants.

Newcastle City Council, New South Wales, Australia

This city is saving $32,000 to $37,000 annually on avoided landfill tipping fees by vermicomposting 33 cubic yards per week of biosolids and vegetable scraps in a 1:1 ratio. Potential savings are estimated to be $129,000 to $150,000 per year when they reach their goal of processing 130 cubic yards per week. The resulting vermicompost (40 percent of the input) is harvested weekly, bagged and sold to major supermarkets in Melbourne and Sydney for approximately $67,000 per year.

Oregon Soil Corporation, Beaverton, Oregon, United States

Since 1991, an automated vermicomposting system has been used to process 12 to 14 tons per day of yard trimmings and pre-consumer food scraps collected from supermarkets at a charge of $65 per ton (landfill tipping fees are $80 per ton). The organic materials are ground up and then mechanically applied in three-inch layers by a retrofitted manure spreader on a gantry which travels over the bed of a 120 x 8 x 2.5 foot (960 square feet) "continuous flow reactor." Vermicompost, which is produced in as little as 30 days and sold for $25 a ton, is scraped off the two-inch mesh screen under the raised bed daily, half-an-inch at a time. About 3,000 tons per year of the vermicompost is sold as "Oregon Soil All-Purpose Planting Mix" in one-cubic foot bags in a chain store in four or five states. This pilot-scale reactor cost about $40,000 to construct; another $50,000 was spent to build a greenhouse-like structure and buy a leachate tank and other equipment.

Pacific Southwest Farms, Ontario, California, United States

One of the largest vermicomposting operations in the United States, PSF has 360 windrows measuring 8 feet by 100 feet on their 54-acre site. More than 100 tons of worms are fed four tons per row per week (100 tons per day) of municipal solid "green" waste brought from materials recovery facilities (MRFs). Their feedstocks include manure, tea, untreated wood, food-contaminated paper, and natural-fiber products. About 45 percent of their income is from sales of castings agricultural users; the rest is from tipping fees. Plans for expansion include a 120-acre site in Bakersfield and two other 50-acre sites.

Resource Conversion Corporation/Canyon Recycling, San Diego, California, U.S.

This company vermicomposts 35,000 tons of organic materials each year, including yard trimmings, manure from the San Diego Zoo and Wild Animal Park, and construction and demolition debris. Their vermicompost, which is marketed under the trade name VermiGro, sells for $35 per cubic yard (regular compost sells for $5 per cubic yard).

Rideau Regional Hospital, Perth, Ontario, Canada

Officials at this 725-bed hospital, with 1000 staff members, decided to vermicompost the 825 pounds of wet organics produced each day. A pulper reduces the amount of food scraps by half, by removing the water. They constructed 20 bins, each 3' x 4' x 30" high, filled them with shredded newspaper and soil bedding, and added a total of 100 pounds of redworms. The beds are located in a greenhouse, which has to contend with temperatures ranging from 86F degrees to 22F below.

San Quentin Prison, California

In 1994, San Quentin Prison added vermicomposting to its Recycling and Salvage Program (RASP). Starting with two 10-foot by 3-foot worm bins, within three years they expanded to 15 bins, all constructed from salvaged scrap wood from the prison recycling center. In 1996-97, worms consumed 400 pounds of food scraps weekly, producting 11,000 pounds of castings and an extra 17,000 worms. Food scraps from the prison ranch kitchen are collected and buried daily in the worm bins, and paper collected from all offices at the prison is shredded and added to the bins as bedding. One or two inmates are assigned to the vermicomposting center each year to maintain and harvest the bins. Every four to six months, the bins are harvested for castings and excess worms. Although most of the castings are used by the prison landscaper in San Quentin's garden areas and flower beds, leftover castings are placed into buckets recovered from the prison's main mess hall and sold to prison staff to use on their house plants and gardens. Prison staff may also purchase harvested worms to use as fishing bait or to start their own worm bins. Prison officials are pleased with the success of the vermicomposting program, as it not only diverts food scraps from the landfill and provides the prison with a valuable soil amendment, it produces an income that supports their recycling program.

Seattle Kingdome Stadium, Seattle, Washington, United States

In 1994, the stadium's successful recycling program was expanded to include vermicomposting. About 18,000 worms in 12 containers eat 50 pounds of food scraps (30 percent of the stadium's total food waste) per week. The worms live in a bedding of leaves and shredded newspaper, and eat mostly pre-consumer salad scraps. They report no problems with odors or pests, and the worm castings are used on the Kingdome's flower beds.

Sovadec, La Voulte, France

Since 1991, this company has been operating on Rhone River in the south of France, vermicomposting 20 tons of mixed household waste per day. A thermal process opens plastic bags filled with refuse, and the contents are separated by automated equipment and hand sorters. Textiles, paper, cardboard, plastics, glass and metals are recycled, and the remaining materials are composted aerobically to eliminate pathogens, weeds and other harmful organisms. Next, the organic materials are processed in 'lombricubateurs' (earthworm tanks) which each have a 15 ton per day capacity, using 1,000 to 2,000 million redworms of the variety eisenia andrei. The resulting vermicompost meets most stringent European standards; non-organic material is less than 50mm in size.

Vermiculture Production Center, Pinar del Rio Province, Cuba

The largest of Cuba's 170 vermicomposting centers, this facility uses cow manure as its primary feedstock, in addition to pig and sheep manure, sugar cane pulp, coffee pulp, and other crop residues. The feedstock is thermophilically composted in twice-weekly turned windrows for 15 to 30 days before being fed to the worms. Vermicomposting takes place in windrows covering four hectares of orchard land. Thin layers of feedstock are spread by a tractor-drawn manure spreader. When the windrows reach a height of 65cm, worms are drawn to the surface with a layer of fresh feed, then five to seven days later a front-end loader is used to skim the top 10cm off of the windrow, removing 80 percent of the worms. The worm harvest can be brought to 90 to 92 percent with a second feeding and loader pass. A mechanical harvester is used to separate the worms from their castings. Castings are used to replace manure as a fertilizer for tobacco; they are also applied to corn, tomatoes, garlic, onions, and coffee bush nursery stock.

Vermicycle Organics, Inc., Charlotte, North Carolina, United States

More than five tons per week of swine manure solids is being vermicomposted at a farm in Wilson,North Carolina. Manure that has passed through an automated solids separator between the swine house and lagoon is placed on a 15 x 15 foot concrete pad. A front-end loader transports the manure to a 30 x 200 foot greenhouse, and a spreader delivers manure to 2 x 190 foot wooden worm beds which each hold thousands of pounds of redworms. Temperature and moisture are controlled through the use of greenhouse curtains, shade cloth, fans, and an automatic mister. Castings are lifted and conveyed from the beds every other month by a retrofitted machine, and a harvester separates worms and eggs from the castings. Castings are sold in 2-, 10- and 25-pound bags marked "Vermicycle: Nature's Ultimate Plant Food." Less than eight weekly person-hours are required to manage the operation.