Communities hungry to divert food waste are sampling new organics processing techniques.

August 1, 2011

9 Min Read
A Tasting Plate of Food Waste Processing Techniques

By Jennifer Grzeskowiak

Food waste programs are on the rise and will continue growing nationwide, despite the weather, federal and state regulations, and other challenges. That’s because communities across the country are united by their desire to divert food scraps from landfills, while the waste industry continues to explore new technologies to create more valuable end products from processed food waste and organics.

One example is the food waste operation in Dubuque, Iowa, which grew from a pilot program in 2006 to a permanent fixture with a waiting list of residents and businesses, ranging from casinos to hospitals. The program’s capacity, however, remains static until the Iowa Department of Natural Resources raises the weekly tonnage cap for co-composting food scraps at yard waste facilities.

In California, the Central Contra Costa Solid Waste Authority (CCCSWA) has been sending its commercial food waste to the East Bay Municipal Utility District’s (EBMUD) wastewater treatment plant for anaerobic digestion. CCCSWA is awaiting the permit for a closer transfer station to grind food waste so that more scraps can be transported daily.

Meanwhile, Seattle, whose residents must either compost at home or participate in the city’s subscription-based food waste collection service, may completely ban food waste from its trash in the not-too-distant future.

Testing Technologies

Traditionally, municipal solid waste (MSW) is landfilled, used for fuel in waste-to-energy plants, recycled or composted. Food waste can be processed by composting, either at home or in large commercial composting operations; anaerobic digestion, which produces biogas that can be used to generate electricity; or gasification, a thermal process resulting in synthetic gas. That syngas can then be turned into electricity or fuels.

Houston-based Waste Management plans to test a new processing technology that will convert organics to ethanol. The company says it will have a facility online within the next 12 months. During the next two years, the company also is considering a project that would convert food waste to gasoline.

The biggest issues these and similar technologies face in the United States and abroad are cost and scalability.

“If these new technologies don’t pan out, we’ll be left with composting and anaerobic digestion,” says Bryan Staley, president of the Raleigh, N.C.-based Environmental Research and Education Foundation. “Those can be profitable, but people are hungry for an end product that exploits the potential of food waste.”

“We need to create the highest value material we can and share that along the value chain,” adds Tim Cesarek, managing director of organic recycling solutions for Waste Management. “That has to be the case to incentivize people to create an industry.”

Creative in Contra Costa

Determined communities are capitalizing on currently available resources to create programs that fit their needs. For many, anaerobic digestion facilities aren’t available and large-scale construction can be too costly. But the method is viable for the CCCSWA.

In 2008, CCCSWA began taking advantage of the nearby Oakland EBMUD wastewater treatment plant, which had excess processing capacity. The anaerobic digestion process produces electricity used to power the plant. For food scraps to be usable by the facility, the material has to be extremely clean — a challenge for any food waste program — and ground to within 2 inches or less.

With the help of California-based consultant Environmental Science Associates, CCCSWA selected 25 restaurants and grocery stores to participate in the program, and then closely trained them regarding what materials were acceptable. The generators weren’t able to add post-consumer food waste until they had proven their ability provide clean material. Trusting businesses to provide contaminant-free material was a risky proposition, but it has since paid off.

The San Francisco Department of the Environment also uses the Oakland EBMUD wastewater treatment plant to process its food scraps, but grinds, hand-picks and trommels the material before sending it. CCCSWA determined this would be too costly.

WILL IT BLEND?: Sometimes food waste is ground into a more uniform product before it is used in anaerobic digestion facilities. (Photo courtesy of the Central Contra Costa Solid Waste Authority.)“We needed a cheaper approach because we didn’t want to pass on the cost to users and have that be a disincentive,” says Bart Carr, senior program manager for CCCSWA.

The program has expanded to include 160 businesses, with Whole Foods claiming the title of largest generator. Allied Waste Services picks up the material one to three times a week, Monday through Saturday, averaging 9.7 tons per day. CCCSWA’s goal is to add nearly 200 more commercial customers within 12 to 18 months.

Program capacity will increase considerably this summer when Allied’s Contra Costa Transfer and Recovery Station in Martinez receives its revised permit to grind food waste separately from yard waste. Until then, the food scraps are being trucked approximately 35 miles to Allied’s Newby Island Facility in Milpitas for grinding before being transferred back to Oakland. Once the Martinez facility is properly permitted, a truck will be able to make morning and afternoon trips, rather than being limited to just one trip a day.

Other solid waste authorities have shown an interest in CCCSWA’s approach. Carr says his department has been contacted by local managers considering using EBMUD for anaerobic digestion, as well as by communities across the country interested in the concept. CCCSWA even has fielded an inquiry from Argentina.

Steady in Seattle

For some communities, composting continues to make the most sense. Seattle, which began accepting vegetative food waste along with yard waste in 2004, sends its food scraps to the Cedar Grove facility in Everett, Wash., for composting.

Seattle Public Utilities (SPU) took a big step forward with its residential program in 2009 when it switched to weekly instead of bi-weekly pickup, and started collecting all types of food waste. It also asked that all customers either subscribe to the service or begin maintaining their own composting bin. Hans Van Dusen, solid waste contracts manager for SPU, says that in the near future, elected officials will likely consider whether to ban food waste from the trash completely.

Meanwhile, Cedar Grove continues to process Seattle’s residential food waste. SPU’s contract with the processor runs through 2013, with multiple one-year extensions. Cedar Grove, which composted approximately 75 tons of food waste last year, is in the final permitting phase to add a 50,000-ton capacity dry fermentation processor designed by Germany-based BioFerm Energy Systems to its Everett facility. Van Dusen estimates that the material from Seattle’s residential program is about 90 percent yard waste and isn’t wet and heavy enough to serve as a feedstock for the operation. Cedar Grove itself, however, collects commercial food waste from Seattle and other communities, providing much of the needed density.

“They want to diversify their technology,” Van Dusen says. “They aren’t just going to switch from composting.”

Cesarek says Seattle is an example of a community developing incentives for the end market before enacting a ban. SPU gradually built its food waste program, as it did with recycling. Seattle began a voluntary program in 1988, but didn’t ban recyclables from the trash until 2005.

“You have to have a plan around organics because you have to understand the capacity of the radius where it’s collected,” Cesarek says. “You have to understand volumes and appropriate processing capacity, and you need to have beneficial reuse. We’ve often said, ‘What’s a ban without a plan?’”

Nevertheless, bans, diversion targets and zero waste goals proliferate. The majority of Fortune 500 companies have zero waste goals.

“What you have is a very strong desire across the country, in terms of zero waste by large waste generators, to lower waste management costs and divert materials for disposal,” says Chaz Miller, state programs director for the Washington-based Environmental Industries Association.

Cities, too, are looking to better manage their waste stream. Austin, Texas, aims to reduce the amount of waste it landfills by 90 percent by 2040. San Francisco already has a 77 percent diversion rate, but plans to achieve zero waste by 2020.

Even for communities that have tackled recyclables and are ready to move on, food waste presents a special set of hurdles.

“Food waste has been more difficult because of vectors and how to deal with the composting side,” Miller says. “And there’s smaller infrastructure, but that’s starting to expand.”

Dedicated in Dubuque

Dubuque, Iowa, is all too familiar with the obstacles that infrastructure can present. Named one of the “most livable cities” in America by the U.S. Conference of Mayors in 2008, Dubuque is focused on sustainability, and that includes its waste stream. The city offers residents an online dashboard that they can use to track their electricity and waste and water usage to better understand their carbon footprint.

Paul Schultz, resource management coordinator for the city, has training in composting operations and 18 years of experience as an organic farmer. He helped develop Dubuque’s residential food waste pilot program, which began as seasonal co-collection with yard debris in 2006. The Dubuque Metropolitan Area Solid Waste Agency (DMASWA) now collects year-round if requested by residents.

With 220 households participating and 60 on the waiting list, there is clear demand for the program, as well as for the end product. Schultz says all the compost usually sells within four hours.

A commercial hauler is poised to collect commercial food waste separately once it receives permission. The Iowa Department of Natural Resources, however, currently caps the amount of food waste that can be co-composted at a yard waste facility at 2 tons. DMASWA is pushing to get the limit raised to 6 tons per week, if not more.

“It’s a huge barrier,” Schultz says. The cost to turn the facility into one that can also accept food waste for composting without any caps is too high, he adds. For now, the city will continue co-composting and exploring other options to boost capacity.

Despite all of the interest in food waste recovery, it’s still not very widespread, says John Culbertson, a principal with MidAtlantic Solid Waste Consultants. “Just a couple hundred communities have programs. It’s still in its infancy.”

Food waste diversion may be young compared with other methods of handling solid waste. But as the interest surrounding it matures into proven collection programs and processing technology, the payoff could be even greater than with other materials.

“I don’t think we’re that far off,” Cesarek says. “There are some things we still need to learn to make it a reality. That’s the technological push that needs to occur for the diversion goals to be met.”

Jennifer Grzeskowiak is a Laguna Beach, Calif.-based contributing writer. She was formerly the managing editor of Waste Age.

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