March 28, 2005

Dufferin organics processing facility functioning well, say city officials

Toronto's Dufferin organics processing facility is working as expected and according to plan, contrary to recent negative press reports, councillor Jane Pitfield, head of the city's works committee, said recently.

"The Dufferin plant is the first of its kind in North America and the business of processing organics is rather new," Pitfield pointed out. "The plant is a good, reliable facility, however when its capacity is doubled we will begin heating and lighting other buildings with the methane. We will work to reduce the waste that is sent to Michigan."

Earlier this month, the works committee received a staff report providing a preliminary evaluation of the facility and updating the plant's anaerobic system that processes Green Bin organics. The proportion of residue from the organics processing that goes to Michigan landfill is a planned by-product. The city purposely allows Green Bin participants to use plastic bags to dispose of their organics knowing that the bags, being non-compostable, ultimately require landfill.

"Plastic bags contribute to the hygenics of the program and are offered as a convenience to residents," explained Geoff Rathbone, Director of Policy and Planning for Toronto's Solid Waste Management Services. "It also gives these bags a second life in that they are re-used." The city is exploring options for recycling plastic bags should a sustainable market be found.

Organic residuals break down into three natural elements: liquid, methane and solids. Organics have an extremely high moisture content, especially fruit and vegetable waste. Some of the moisture evaporates but the remainder, once separated from the solids, becomes a water-based liquid which is diverted from landfill and properly treated.

Close to 90,000 tonnes of organics are sent for processing to facilities such as those in Guelph and Quebec, which use an aerobic system, and one in Newmarket which, like Dufferin, uses an anaerobic system. The anaerobic system requires less land than an aerobic one, making it better suited to Toronto's urban environment. It also allows the city to pursue the capture of methane as an energy-from-waste resource.

As a demonstration plant, the Dufferin facility is not currently of an economic scale to justify installing electric conversion systems to permit the capture of methane to produce electricity. In view of methane's value as an energy-from-waste by-product, the city plans to capture the methane once its proposed plans to expand the Dufferin facility are realized.

In the meantime, the methane is combusted to carbon dioxide (CO2). The carbon content in the CO2 is biogenic, i.e. derived from plants and animals, resulting in a zero net greenhouse gas impact.

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