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As material recovery facilities (MRFs) become larger and more sophisticated, the opportunity to develop processes for organic waste is growing right alongside it. 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.

“Some of the things that are occurring in recycling, we are also seeing in waste conversion,” he told attendees. “We have a very integrated system, so whatever occurs in one element has an impact on the other element as well.”

Rathborne said that five years ago, the average MRF in North America processed 30,000 tons of material per year.

“What we are seeing now is a major shift towards much, much larger MRFs, in the range of 200,000 tons per year,” he said. He attributed the larger MRF model to be a result of an increased emphasis on recycling from business and communities and a greater interest in plastics recycling.

The more sophisticated equipment, such as optical sorters, needed to recover plastics from the single-stream facility involves a major capital investment. “In order to justify that capital we need to have MRFs that are much, much larger in scale,” Rathborne said.

Feeding a larger MRF has led to the development of more hub-and-spoke systems for collecting material. The hub is the large centralized MRF facility that may require material to be sourced from locations as far as three or four hours away, in order to reach full 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.

He acknowledged that not all regions present the same opportunities with organics.

“When we looked at organic processing opportunities across North America, the one thing we recognized is that one size does not fit all.”

For example, in locations where tipping fees are between $20 and $30 per ton, an open windrow aerobic site may be all that is necessary.

Where tipping fees are $70, $80 and $90 per ton, such as on the West Coast, he said, “Then we begin to see the opportunity for anaerobic digestion (AD) and source-separated organics from residential and commercial [streams] and even tying [them] in with biosolids.”

Growing Interest
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 household organics collection five years ago.

“I think this has caused other cities across Canada with similar conditions to also move towards source separation of kitchen organics in their residential program,” Rathborne said.

He predicts that over 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. (See the chart at bottom.)

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 is accepted in Toronto’s program. Diapers and sanitary products, animal waste, animal bedding, kitty litter and soiled paper also are accepted in the program. “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 has the ability to share its infrastructure with the landfills and wastewater treatment plants it operates. Colocating would allow for a much quicker implementation period since the company was already capturing landfill gas, 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 Progressive Waste to co-process residential and ICI (industrial, commercial and institutional) material, cocompost materials (aerobic and anaerobic) and corefine biogas and landfill gas.

“We also believe that by looking at this 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.”

For municipalities, it would mean no capital risk, long-term fixed fees and lower costs per ton, according to Rathborne.

Progressive Waste could realize another benefit from AD, according to Rathborne. The company’s solid waste fleets are rapidly converting to compressed natural gas (CNG) powered vehicles. Up to 70 percent of new collection vehicles purchased by Progressive Waste are CNG fueled.

“This provides us with a great opportunity to literally make our own fuel with anaerobic digestion,” said Rathborne. He estimated a typical collection truck uses about 10,000 gallons of diesel per year and that a 100,000-ton-per-year AD plant can fuel 125 waste trucks. Progressive Waste is working with Anaergia, a renewable energy from organic waste solutions provider based in Burlington, Ontario, for the development of its AD systems.

The Waste Conversion Congress West Coast was Nov. 28-29, 2012 at the Renaissance Hotel in Long Beach, Calif.

The author is managing editor of Renewable Energy from Waste magazine and can be contacted at [email protected].