Waste Not, Want Not

It may have a sullied reputation, but wastewater may soon prove to be a valuable energy source. A U of T study indicates that the energy stored in Toronto’s municipal wastewater could be harnessed to run treatment facilities and contribute to the city grid.



The study, published in the August issue of the Journal of Energy Engineering, measured the energy content of the raw municipal wastewater in the Ashbridges Bay, North Toronto, Highland Creek and Humber plants. The research revealed that the wastewater contained enough organic material to potentially produce 113 megawatts of electricity.



”With a 20 per cent recovery of that potential energy into electricity, the wastewater treatment plants could produce enough electricity for their own operation,” says civil engineering professor David Bagley, who conducted the research with lead author and PhD candidate Ioannis Shizas. “Any recovery of potential energy above that can be returned to the grid.”



Bagley and Shizas used bomb calorimetry, a technique that measures the heat content of materials, to determine the amount of energy stored in wastewater’s organic matter. 



“We’re moving toward a future where we see our wastewaters and other wastes as resources,” says Bagley. “If electricity costs go up, like they have in places such as California, this could be a cost-effective and renewable energy source.”