Canadian Consulting Engineer

News

Toronto research shows sewage as an energy source

Research in Toronto has found that the raw wastewater in four of its municipal plants could produce 113 megawatts o...


Research in Toronto has found that the raw wastewater in four of its municipal plants could produce 113 megawatts of electricity per year — enough to make the plants self-sustaining from an energy point of view.
David Bagley, the civil engineering professor at the University of Toronto who conducted the research, says: “With a 20 per cent recovery of that potential energy into electricity, the wastewater treatment plants could produce enough electricity for their own operation. Any recovery of potential energy above that can be returned to the grid.”
The four city plants — Ashbridges Bay, North Toronto, Highland Creek and Humber — currently use aerobic processes to treat the wastewater. By using anaerobic digestion instead, where the microbes decompose without oxygen, they would produce a methane-rich biogas byproduct with an energy content approximately 75 per cent that of natural gas.
“We’re moving towards a future where we see our wastewaters and other wastes as resources,” says Bagley. He noted that pulling energy from waste would become even more viable as electricity prices continue to rise.
Bagley, and Ph.D. candidate Ioannis Shizas used bomb calorimetry to measure the heat content of materials and determine the amount of energy stored in the organic waste mater.
www.news.utoronto.ca