As municipalities, institutions and businesses are adopting policies to divert as much as possible from landfills and even committing to zero-waste initiatives, the recycling of paper, plastics, glass and metals will only get them so far. Looking for additional ways to divert material from landfills has become a necessary step in achieving sustainability goals.
The U.S. Environmental Protection Agency (EPA) reports that more food reaches landfills and incinerators than any other material in municipal solid waste (MSW). Of the 34 million tons of food waste generated in the United States in 2010, EPA estimates only 3 percent was diverted for composting. That low percentage of diversion could be seen as an opportunity by some to develop processes to use such an abundant material stream. EPA offers several suggestions for reducing food waste, including:
- Source Reduction or Prevention—Preventing food waste before it is created;
- Feeding People—Donating fresh, wholesome food to those in need;
- Feeding Animals—Feeding safe, fresh food scraps to animals;
- Industrial Uses—Rendering fats, oils and grease into products or biofuels;
- Composting—Turning food waste into a valuable soil amendment;
- Anaerobic Digestion—Turning food waste into renewable energy and a valuable soil amendment.
Fuel creation, composting and anaerobic digestion (AD) have seen increased interest over the past few years as the solid waste industry, communities and technology providers have capitalized on the benefits of diverting food and other organic material from landfills.
This issue of how best to handle organic waste has even gotten the attention of WasteExpo organizers, Penton Media’s Waste Industry Group. The company planned additional programming at this year’s event in New Orleans focused on organics and composting. The group’s Steven Averett notes, “The ongoing debate over how best to handle this material, be it through composting, anaerobic digestion or disposal in a gas-to-energy landfill, will be a defining issue for the industry in the coming years.”
One thing is certain: removing organics from the waste stream can boost landfill diversion rates. In just six months after implementing new waste collection services in San José, Calif., that included sorting out food waste, businesses increased their average recycling rate from 22 percent to almost 70 percent between July and December 2012, according to a press release issued by the city.
The new waste collection services in San José began July 1, 2012, and provided a two-container wet/dry sort for businesses. Wet items accepted into the program include organics, such as food waste, used napkins and paper plates and landscape trimmings. Dry items include glass, paper, plastics, cardboard and metals.
The city of San José is in the process of constructing a dry fermentation anaerobic digestion system to process organic waste. During a webinar on organic waste diversion held in January, Michelle Young, organics manager for the city of San José, said of the project, “This is a big experiment in the U.S. to see how these systems will integrate into our current solid waste infrastructure.”
She added, “Anaerobic digestion is really a critical tool for us to consider and integrate where it makes sense into a fully integrated solid waste system.”
One of the key drivers for San José’s decision to begin processing food waste was its “Green Vision” initiative that was developed in 2006.
In it, the city committed to 75 percent diversion by 2013. By the year 2022, San José has committed to zero waste, 100-percent-renewable energy and a 100-percent-green city fleet. Young said the city is on track to meet its 2013 goal.
When looking at solutions for organic waste, San José determined it had excess digester capacity at its wastewater treatment plant. The city also was aware of the air impact on open windrow digestion and bagged composting. Additionally, the nearest composting facility was also a 30-mile haul, which had its own environmental implications. These drivers led the city to put an integrated strategic planning process on the table, Young said.
When the city sought requests for proposals (RFPs), it specified that the solid waste solution include use of the wastewater treatment plant for its commercial agreement. The city put out two separate requests for proposals—one for collection and one for organics processing.
The city awarded the collection contract to Republic Services, Phoenix. The organics processing contract was awarded to Zero Waste Energy Development (ZWED), a local conglomerate made up of Zanker Road Resource Recovery and GreenWaste Recovery. The organics contracts included the use of ZWED’s Kompoferm dry AD technology system. The agreement also allowed for the woody fraction, yard waste and paper waste to be sent to the Z-Best Compost Facility. Until the AD system is complete, San José is using a white bag system that composts the organic waste.
Young said the reason the city chose ZWED is, “They have been innovators for us and with us on their MRF- (material recovery facility-) sorted organics, back-end processing and other innovative technologies. They’ve partnered for many years with Bulk Handling Systems, who they will continue to work with, and Zero Waste Energy [a separate company from ZWED].”
The AD system is scheduled to begin receiving materials in the fall of 2013. In the experimentation phase, some of the feedstock has been directly delivered to the facility and some has been processed at the Newby Island MRF, where it is debagged and run across a line. Young said the city is currently analyzing material to optimize the sorting process.
“As we move forward, we will be learning how the system goes and how to optimize it. It is a huge issue for the industry, and we really need to look at that together and learn from each other.”
As MRFs become larger and more sophisticated, the opportunity to develop processes for organic waste is growing as well. During the Waste Conversion Congress West Coast, held in late November 2012 in Long Beach, Calif., Jeff Rathborne, vice president of recovery for Toronto-based Progressive Waste Solutions, North America’s third-largest waste management company, talked about how the company plans to capitalize on this trend.
“What we are seeing now is a major shift toward much, much larger MRFs, in the range of 200,000 tons per year,” Rathborne said. He said this model was the result of an increased emphasis on recycling from business and communities and a greater interest in plastics recycling.
The need for larger MRFs has led to the development of hub-and-spoke systems for collecting material. A large centralized MRF acts as the hub, sourcing material from locations as far as three or four hours away to reach full processing capacity.
Not only are dry recyclables brought to the transfer stations, but organics and nonrecyclable materials also are taken there.
“What we see is the opportunity at these transfer points to not only accumulate recyclables for transfer but also the opportunity to accumulate organic material for transfer to larger centralized organic processing facilities,” said Rathborne.
In Canada in particular, Progressive is seeing an explosion in AD. Toronto has one anaerobic digester and is building another. The city began a “green bin” program for the collection of household organics five years ago.
“I think this has caused other cities across Canada with similar conditions to also move toward source separation of kitchen organics in their residential program,” Rathborne said.
He predicted that in the next five years, green bin source separation will be available in most of Canada’s major cities, including Vancouver, British Columbia; Calgary, Alberta; Montreal; and Winnipeg, Manitoba.
“As these municipalities move toward green bin, we also see very strong interest from local commercial and industrial sources,” added Rathborne. “One of the key trends we see with this hub-and-spoke technology and the move to larger centralized facilities is the ability to coprocess recyclables and coprocess organic materials from I&C (industrial and commercial) and residential sources.”
With coprocessing, the volume of material increases, allowing for the economy of scale needed from a capital and operating standpoint to “make these facilities very doable,” said Rathborne.
Residential green bin collection represents about half of the organic feedstock collected in Toronto. Restaurants make up about 30 percent of the organics. Grocery stores, food processing and fat, oil and grease (FOG) make up the remaining portion of the organics stream.
A key advantage of the city of Toronto’s organics program, according to Rathborne, is that it uses AD to process organics as opposed to an aerobic system. Using AD allows residents to place their organics into a regular plastic bag for curbside collection, making it easy to collect and helping to manage the “yuck factor,” he explained.
All forms of food waste are accepted in Toronto’s program. Diapers and sanitary products, animal waste, animal bedding, kitty litter and soiled paper also are accepted. “Anaerobic digestion is very tolerant and allows a broad range of materials,” Rathborne explained. “Suddenly you are touching not just food waste material but other products households have that they really want to divert from landfill.”
Rathborne describes Toronto’s program as an “easy-to-use and tolerant system” with a broad list of acceptable materials that, combined with a fee on garbage, has led to significant capture rates from residential collection—450 pounds per year per single-family home and 165 pounds per year per multifamily unit.
“We’ve been looking at how to be part of the explosive growth of AD in Canada and the U.S.,” said Rathborne. “We believe our Progressive Waste facilities are very well-suited to site AD.”
Rathborne explained how Progressive Waste can share infrastructure among the landfills and wastewater treatment plants it operates. Colocating provides additional advantages, he contended.
“We can very significantly reduce the cost if we colocate at a landfill. It allows for a much quicker implementation period,” he said. Colocating would allow the company to coprocess residential and ICI (industrial, commercial and institutional) material, cocompost materials (using aerobic and anaerobic processes) and corefine biogas and landfill gas.
“We also believe that by looking at the coprocessing of residential and ICI organics, we would be reducing our cost by 30 percent,” Rathborne said. “We also think it provides a great opportunity for municipalities to not have to build their own facilities but to use a vendor to have their material processed.”
Ahead of the Class
Municipalities are not the only waste producers interested in food waste diversion. A number of educational institutions are developing and implementing systems to handle the food waste they produce on their campuses.
At Appalachian State University in Boon, N.C., students have been recycling campus food waste into a compost soil amendment for use in campus flower beds since 1999. In 2010, construction began on a new compost facility that will allow the school to expand its food waste collection program and receive up to 275 tons of food waste per year.
The University of Wisconsin Oshkosh has taken its food and yard waste diversion one step further, using it to produce energy to power a portion of the campus. In 2011, it installed a combined-heat-and-power (CHP) dry fermentation anaerobic digester with the ability to consume 8,000 tons of material per year. During phase two of the project, it will be able produce more than 4,000 megawatts of thermal energy and 3,000 megawatts of electricity per year.
Michigan State University (MSU) is building an anaerobic digester at its Dairy Cattle Teaching & Research Center on the South Campus Farms that will convert 16,800 tons per year of food waste from campus dining halls, manure from MSU’s dairy farm and food processing waste from the local community into 460 kilowatts of renewable energy. The renewable electricity will be used on campus, while the natural fertilizer created through the process will be used on agricultural land.
“The payback on investment for this project will come from the energy produced, the fertilizer sales and also from tipping fees,” says Dana Kirk, manager of the MSU Anaerobic Digestion Research and Education Center (ADREC).
The organics fraction of the solid waste stream has certainly provided food for thought to a number of municipalities, companies and institutions that are capitalizing on this material.
The author is the managing editor of Renewable Energy from Waste, a sister publication of Recycling Today, and can be reached at firstname.lastname@example.org.