January 24, 2008 | General

Meat Processor Moves To Anaerobic Digestion

BioCycle January 2008, Vol. 49, No. 1, p. 60
JBS Swift is installing digesters at its Nebraska meat processing plant to treat manure and slaughtering by-products. Biogas will reduce natural gas consumption by about 25 percent.
Diane Greer

GUS Swift, the founder of the world’s third largest beef and pork processor, Swift & Company, wasn’t a big fan of waste. To reduce the amount generated by his operations, he pioneered methods to utilize by-products from the process to create soap, gelatin, paintbrushes and even tennis racket strings.
Following in its founder’s footsteps, the 152-year old company took another step toward maximizing the value of its waste streams by breaking ground in December for an anaerobic digester at its processing facility in Grand Island, Nebraska. The system, which is expected to be operational in the fourth quarter of 2008, will process manure and animal slaughter by-products to produce 235,000 MMBTUs per year of biogas – the energy equivalent of 1.7 million gallons of oil, displacing 20 to 25 percent of the natural gas used by the facility.
Microgy, a subsidiary of Environmental Power, will build, own and operate the anaerobic digestion (AD) facility, selling the gas produced to JBS Swift (Swift) under a 15-year purchase agreement. JBS, Latin America’s largest beef processor, purchased Swift & Company, which was the world’s third-largest processor of fresh beef and pork products, in July 2007 for $1.5 billion.
Currently, waste from the plant, including the manure from the 6,000 cows processed in the facility each day, paunch (the stomach contents of cattle – about 24,000 gallons a day), screenings and grit (ranging from 5,000 to 10,000 gallons a day), and oil and grease (about 21,400 gallons a day) are land applied. But land application has resulted in complaints from the surrounding community. When the land is wet due to inclement weather, trucks can’t get into the fields. During these periods, companies hired to haul the materials are supposed to dispose of the waste in landfills. But sometimes they dump the materials along the edge of the fields with the intent of moving it onto the fields later, explains Thomas Siegrist, Swift’s Manager of Environmental Engineering. “In warm weather, you have problems with flies and odors since the material is not incorporated into the soil. That has raised concerns from the general public.”
There are also issues during the winter. “The ground is frozen in Nebraska for quite a few months each year and you can’t effectively incorporate the waste into the soil,” says Mark Hall, Microgy’s senior vice president. “So they are really limited seasonally on what they could do.” Adds Siegrist: “In the long-term everybody recognizes that this is not the way we want to deal with solid waste issues.”
Wastewater from the operation is treated in a 10-million gallon covered anaerobic lagoon. After treatment, the effluent is sent to the City of Grand Island’s wastewater treatment plant. Biogas from the existing lagoon is collected and used to produce process heat for the facility. Swift is currently building a second anaerobic lagoon with a capacity of 27 million gallons. While the lagoons are good for digestion, they are limited in the types of materials that can be processed. “They also take up a lot of space to generate a small amount of energy,” says Michael Hvisvos, executive vice president at Microgy. “By using our system Swift is able to generate a very high output of energy in a very small footprint.”
Microgy is installing two 1.2 million gallon Xergi digesters at the facility. The system will operate at thermophilic temperatures (ranging from 125 to 135°F) with an average retention time of 20 days. Additional tanks will store and mix substrate. Control technology will monitor conditions within the digester to optimize gas yield, quality and reliability.
In a departure from prior installations, Microgy is contracting the design and construction of the facility to a third party, Benham Construction of St. Louis, Missouri. “We are building a lot of projects in parallel and faced a choice, are we going to staff up to manage the projects in-house or use what the market has available in terms of engineering, procurement and construction contractors to help us get the work done?” Hall asks. The company chose the latter course and is currently qualifying contractors to work on upcoming projects.
Materials will be loaded into the digester in a continuous process, with feed rates controlled by monitoring conditions within the tanks, Hvisvos says. Combining manure with the paunch and other codigestion products will boost biogas output. “We have done a fair amount of analysis, and are comfortable with the biogas targets,” Hall says.
After moisture removal, biogas will be scrubbed of hydrogen sulfide and then blended with natural gas to fire Swift boilers. The digester facility will also consume a small amount of the gas to meet the thermal requirements of the digester. Solids will be used for fertilizer. Farmers in the area are excited about getting the solids since they will have a more balanced nutrient content without the odors associated with the untreated organic wastes. “We will not have to haul it as far because it is not as objectionable,” Siegrist says. “People in the past who said no thanks are now interested in using the stuff.”
Liquid effluent from the digester process will be put into the existing lagoon system for final treatment and to capture any residual energy value. Once completed, the second lagoon is expected to replace another 20 to 25 percent of Swift’s natural gas requirements.
The City of Grand Island also will benefit. Under the current processing system, organic loads to the City’s wastewater treatment facility increase during the winter when land application is not viable. “The digester is expected to assure a consistent performance of Swift’s chemical wastewater treatment program,” Siegrist says.
Investigations are underway to bring additional materials from off-site generators, such as area cheese plants and dairies, for processing in the digester. But Swift needs to be sure that materials coming into its site don’t pose any food safety problems, Siegrist explains. Additionally, Swift wants to ensure the digesters are capable of treating all its own wastes before taking material from anyone else. “The land Microgy is leasing from us is great enough in size that they could put additional reactors on the site if that is what is necessary to take care of off-site wastes,” he adds.
In terms of regulatory approvals, some modifications were made to the existing permits to install the digeseters. “This is actually a very simple permitting process because we are able to integrate the new system into all Swift’s existing infrastructure,” says Hall. Current land application permits apply to the digested solids.
Swift is excited about turning a waste stream into a viable renewable energy source. “When there is an opportunity to decrease the concerns of the folks in the surrounding area, realize a cost reduction and have Microgy fund the capital investment in the project, well that’s about as good as it gets,” Siegrist says. “We really like this project.”
Microgy is in discussions with JBS Swift about installing AD systems at other facilities. “Obviously they are very interested in seeing how we bring this first one up,” Hall says. In general, the meat processing industry represents an important new market for the company. “There are a lot of other meat processors that are looking to the success of this project to move into this option as well,” Hvisvos says.
Diane Greer is a Contributing Editor to BioCycle. She can be reached at

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