BioCycle October 2008, Vol. 49, No. 10, p. 36
Regional food bank diverts a slurry to composting in a successful program that it plans to replicate with a second distribution center.
Steve Slipchinsky and K.C. Alexander
FOODSHARE, a member of the Feeding America food bank network, is the regional food bank for Hartford and Tolland Counties in Connecticut. Located in the Hartford Regional Produce Terminal and Markets, approximately one-third of the food distributed by Foodshare annually to food pantries, community kitchens, shelters and other organizations is donated fresh produce.
As the produce program at Foodshare grew, so did its trash bill. In 2002, over two million pounds of fresh produce were donated to Foodshare. As volunteers repacked the fruit and vegetables, the unusable portion was being put in a dumpster along with the trash. The dumpster leaked, smelled and attracted animals. It was also very expensive to send wet, heavy trash to the disposal facility, an incinerator nearby.
To address this waste disposal challenge, Foodshare conducted a three-year pilot program, starting in October 2002. It received a grant from the Connecticut Department of Environmental Protection to purchase equipment to recycle the spoiled produce. The resulting slurry was stored in a tank on site, and then shipped to local farms for composting. During the three years, 377 tons of spoiled produce were composted, saving Foodshare $32,497 in avoided disposal costs.
INSTALLING A SYSTEM
The grant from Connecticut DEP went towards purchasing a forklift with a built-in scale and an Organic Resource Management, Inc. system (ORRS) for recycling organics. ORRS is comprised of a grinding mill produced by Red Goat; an underground fiberglass holding tank; and a small blower for maintaining a negative pressure in the tank.
A 6,000-gallon rectangular concrete holding tank was substituted for the 4,000-gallon fiberglass tank used in the ORRS system. The tank was purchased from Arrow Concrete Products in Granby, Connecticut. The tank was cast to Foodshare’s specification, including openings in the top for loading, access and aeration. The larger tank was chosen to allow for continued use of the system during the time interval between when a vacuum truck was called to empty the tank and when the actual emptying took place.
Foodshare accepts all produce donations that contain at least 75 percent solid viable product. Volunteers sort the usable from the unusable, and produce deemed fit for distribution is repacked and sent to its main warehouse in Bloomfield. The remainder is batch fed by the volunteers into the hopper on top of the ORRS grinder.
The hopper holds about one-third of a cubic yard, and has a top that locks once the unit is turned on (to prevent direct contact). The grinder will process almost any produce item; it takes about 2.5 minutes to process one load, which drops directly into the tank as it is ground. Once processing is completed, the top unlocks and the unit is ready to be reloaded.
The grinder will not process cornhusks or pineapple tops, and can only handle hard vegetables (e.g., winter squash or rutabagas) if they are included in a mixed load with softer vegetables. If cornhusks or pineapple tops are added to the mix, they can stall the auger located directly under the hopper; if they get past the auger and into the mill, they can get caught in the hammers of the mill. In the first case, the grinder must be shut off, the top opened and the unacceptable items removed; in the second case, the side panel on the grinder must be unbolted and the fibrous material removed.
Composting the Slurry
When the 4,000-gallon level is reached (measured with a dipstick), the vacuum truck is called to schedule a time for emptying the tank. Since the truck holds 4,000 gallons and the tank holds 6,000 gallons, ground spoiled produce can continue to be added. The slurry is transported to one of two farms for composting. Foodshare pays the hauler $400/load to pump and haul the slurry to the farm.
Farms accepting slurry from Foodshare must have an Agricultural Waste Management plan. Foodshare located two farms that were interested in accepting the slurry and obtaining the appropriate DEP approval of the plan. Currently, Foodshare is rotating deliveries between Old Maids Farm in South Glastonbury, and Park Farm in Melrose. Each farm is paid a $20/ton ($330/load) tipping fee.
At the farm, the truck offloads the slurry into a receiving area of windrows to provide containment. The windrows consist of wood chips, sawdust, leaves, spent manure or other similar bulking material, which helps absorb the slurry and provides carbon for the composting process. Slurry is unloaded into a trench that goes down the length of the windrow, and then a bucket loader is used to cover it with more bulking material.
The 750,000 lbs (377 tons) of spoiled produce delivered over the course of the three year pilot represents 80 percent of Foodshare’s produce waste; the other 20 percent was too dense or fibrous to go through the mill (and is therefore disposed of in the trash). During most of the time that Foodshare has been using this recycling system, the only other management option for the spoiled produce was a rented six-yard dumpster used for trash. It was emptied “on call” when full, and Foodshare was charged per pickup regardless of how much weight was in the container. This made it impossible to figure what percent of the cost was attributed to the produce waste.
Recently Foodshare installed a trash compactor. Fees for the compactor are as follows: $350/month, $195/pickup and $75/ton. Based on a once per month, 10-ton pickup, Foodshare is spending $130/ton for waste put in the compactor compared to $44/ton with the grinder/slurry system. This represents a savings of $86/ton, or $32,497 over three years.
Foodshare’s organic recycling program has been successful because of a commitment throughout the staff, a vision of “greening” the organization and cost savings. Another key to Foodshare’s success is providing the farmers with a feedstock that is pure vegetable waste. If the slurry were contaminated with glass, plastic or other foreign matter, it would not be acceptable for composting.
Although the ORRS machine worked fine within its limitations, it could not handle fibrous or dense produce, and jammed frequently. Significant maintenance and replacement parts were needed. In Foodshare’s system configuration, some odors were present, but only when the loading hatch was opened. Odor was all but eliminated when citrus fruit was added to the tank. More aeration/agitation resulted in fewer odors.
Evacuating the tank takes longer than anticipated because the slurry gets denser toward the bottom of the tank. Backwashing is required to homogenize the slurry to a consistency that the vacuum truck can handle, adding more time to the process. The evacuation pipes in the original design of the tank were unnecessary. Using the manhole worked better.
Given the equipment changes anticipated, a round holding tank would be better than the square/rectangular tank. For generators of large volumes of produce waste, a system such as the one described can save significant money if staff are willing to take the time to separate the produce from the packaging.
Improvements and Future Applications
Since the completion of the three-year pilot, several improvements have been made, and the recycling program has continued. A chopper pump, manufactured by Vaughn, replaced the ORRS grinder. This chopper pump is more powerful than the original grinder, and is most often used in the agricultural, municipal and industrial sectors for waste management applications. The spoiled produce is added to the tank whole, and the chopper pump processes it faster, thereby reducing handling time. It also homogenizes the slurry.
Recirculation plumbing was installed to help with homogenization and to rechop larger pieces that may have evaded the blade of the chopper pump in previous days. A Vortex blower manufactured and donated by The Spencer Turbine Company in Windsor, Connecticut was installed to blow air into the tank through one fixed PVC pipe, and one flexible hose to help dislodge and circulate the slurry. A stainless steel table was installed as a work surface and a place to stage produce before going into the tank, giving the operator one last chance to pull out plastic and other nonbiodegradable contaminants.
In anticipation of expanding its organics recycling program, Foodshare’s new distribution center in Bloomfield has another 6,000-gallon tank. Plans call for the transfer of the original grinder from its present location at Foodshare’s facility in the Regional Produce Terminal and Market to the new distribution center in Bloomfield. The distribution center does not handle as much produce as the Market location, but does have stale bakery items and damaged/outdated canned and jarred goods that could be opened and emptied into the tank if volunteer labor is available. This would also result in increased recycling of metal and glass containers.
The 4-H garden in Bloomfield grows vegetables for Foodshare with the help of University of Connecticut’s Master Gardeners. Plans are being formulated to “close the recycling loop” by having one 4,000-gallon truckload of vegetable slurry trucked to the site, where it will be used in the production of compost for the garden, and in turn, to grow vegetables for Foodshare.
Steve Slipchinsky (firstname.lastname@example.org) is Project Manager for the organic recycling program at Foodshare. K.C. Alexander is an Organics Recycling Specialist with the Connecticut Department of Environmental Protection’s Recycling Program, in the Bureau of Materials Management and Compliance Assurance. The full report is available at : http://www.ct.gov/dep/cwp/browse.asp?A=2718.
October 22, 2008 | General
Food Bank Recycles Spoiled Produce
BioCycle October 2008, Vol. 49, No. 10, p. 36