Canada’s Toronto City Council has voted to negotiate a final deal to build an anaerobic digestion facility to process up to 90,000 tonnes per year of the city’s food waste. Australia’s Lisa Brown, who visited the city’s pilot plant as part of a Churchill Fellowship study tour last year, said the move will consolidate the region as a leader in source separated organics recovery in North America.

Toronto has operated a demonstration AD facility for the past eight years, processing up to 40,000 tonnes per year of source separated food waste. The original design was for 25,000tpa capacity, but operation of the plant has gone better than expected, including in regard to odour emissions – despite operating in a light industrial area of the city, it is one of the few waste facilities in the province that hasn’t fell foul of Ministry of the Environment “control orders” in regards to odour.

The new facility will be built inside the city limits at one of the city’s waste transfer station properties. The biogas from the facility will be cleaned to produce high grade methane that will ultimately allow the city to convert its fleet of collection vehicles from diesel fuel to methane.

The facility is designed to use almost no city water but will instead collect rain water for cleaning purposes. A full wastewater treatment plant (using biological nutrient removal) will allow the facility to discharge water (primarily water removed from the food waste) that meets all municipal requirements.

The city plans to upgrade the original demonstration facility to increase capacity and to generate renewable energy as well.

Providing Inside Waste regular updates during her study tour last year, Impact Environmental’s Lisa Brown reported that source separated organics collection and processing was very widespread in the greater Toronto area, with approximately 1.9 million single dwellings having access to a food organics collection service.

Toronto collects a very wide range of organics, including soiled nappies, cat litter and hair, in addition to all cooked and uncooked fruit, vegetables, meat, bones and dairy. Interestingly, the city allows residents to use plastic bags for the food/organic material and relies upon AD to process its material.

Brown said the city had a “very impressive” participation rate of over 90% (for single dwellings) and appeared able to separate the plastic bags out of the organics at the processing facilities.

“I visited one of the composting plants that accepts the digestate from the AD facility and was surprised to learn the contamination in the digestate was manageable and the final compost made the highest grading,” she wrote.

With the AD component of its waste management plans moving forward, the city is also currently going through a lengthy process to ultimately build a facility to process the remainder of the waste it is currently sending to landfill.

This process will be designed to remove any remaining recyclable materials (metals, plastics, paper) along with any remaining organics, which will also be digested to produce renewable energy.

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