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Anaerobic digestion key to reducing Ontario GHG emissions

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Ontario, Canada’s Environmental Commissioner Dianne Saxe has called for more investment to create biogas from human and food waste, particularly highlighting the potential for anaerobic digestion (AD) in the province’s wastewater treatment sector.

“Most Ontario wastewater treatment plants do not use anaerobic digestion. Of those that do, the majority flare (and thus waste) at least some of the energy. To achieve Ontario’s goal of reducing greenhouse gas emissions, anaerobic digestion and energy recovery should become standard at wastewater treatment plants whenever practical.” Writes Saxe in Every Drop Counts, her annual report on energy consumption in Ontario.

“Even better, treatment plants could become “energy centres” that also produce and capture methane from a wide range of supplemental organic wastes.” Saxe continues. “Keeping organic wastes out of landfills is essential to Ontario’s circular economy strategy, and capturing the methane from such wastes is important for meeting climate targets.

“This opportunity will be challenging to realise, but it offers so many benefits that it deserves focused government attention and support.”

Saxe cites the enormous potential for anaerobic digestion in Ontario, explaining that of the 2 billion m3 of municipal sewage produced every year, 68 million m3 a year could be turned into renewable natural gas through anaerobic digestion.

If other forms of organic waste were also processed through AD, such as livestock manure, crop residue or organics in municipal solids waste, Ontario could meet 6% of its natural gas demand, in turn reducing emissions by about 2.7 Mt/year carbon dioxide equivalent (CO2eq), or roughly 2% of provincial emissions.