U of G Researchers Improving Organic Waste Disposal Efficiency
The beloved green bin is home to many different forms of organic waste, such as food remains, pet waste, yard trimmings and paper towel. Thirty-two per cent of Ontario’s waste stream, or 3.7 million tonnes, is categorized as organic waste. Many don’t know that while putting your food in the green bin is more eco-friendly than putting it in the trash, “green” waste can still pose an environmental hazard. These hazards include contamination of surface and groundwater, contributions to global warming and ecosystem damage.
An important focus in waste management to support sustainability is called “recovery”, the process of generating energy from waste. One of the processes for this waste-to-energy conversion is called “Anaerobic Digestion,” which breaks down organic matter to produce biogas and digestate, a fertilizer. The output biogas, a mixture of methane and carbon dioxide, can be used to produce heat or burned in a specific process to produce electricity.
There are two main methods of anaerobic digestion – dry and wet. Wet anaerobic digestion is the most common approach, but unsuitable to processing solid or dry waste. Dry anaerobic digestion can convert dry waste into biogas.
Energy Production using Anaerobic Digestion
Dr. Animesh Dutta, a professor in the University of Guelph's School of Engineering, Dr. Omid Norouzi and their team at the Biorenewable Innovation Lab (BRIL) conducted research on dry anaerobic digestion. This anaerobic digestion process has the potential to process 20% or more of the total solid waste, waste which is currently not processable by wet anaerobic digestion methods. Organic waste typically does not meet the moisture requirement for wet anaerobic digestion and this makes the improvement of dry anaerobic digestion processes important.
The team focused on determining the optimal limit for “thick digestate recirculation” in start-up and steady-state models. Thick digestate recirculation is an important concept in anaerobic digestion that involves adding new feedstock (organic waste) to the top of semi-digested sludge and mixing the two together. Improving the thick digestate recirculation process can improve biogas production and reduce the energy consumption of the process – rendering dry anaerobic digestion more eco-friendly than the existing wet process.
Future of Dry-Anaerobic Digestion
The team’s ultimate goal is to provide a new option for waste treatment plans that allows them to increase their energy efficiency, cost effectiveness and become more environmentally friendly.
“Modern processes such as dry anaerobic digestion could help cities and industries reduce landfill waste, produce renewable energy, and cut greenhouse gas emissions,” says Norouzi.
“The challenge is fine-tuning the system—how much waste should be fed in at a time? How should digestate be recirculated for the best biogas yield? This research aims to answer these questions, making dry anaerobic digestion a practical, scalable solution for waste management facilities.”
Norouzi also further encourages students to reflect on their role in environmental preservation.
“I want to emphasize that waste management isn’t just about garbage—it’s about sustainability, energy, and the future of our planet. There’s a huge need for fresh ideas and innovative solutions. Most importantly, know that sustainability needs problem-solvers like you. Whether through research, engineering, policy, or business, you can play a role in making waste management smarter, cleaner, and more sustainable.”
This story was written by Izabela Savić as part of the Science Communicators: Research @ CEPS initiative. Izabela is a PhD student in the School of Computer Science under Dr. Daniel Gillis. Her research focus is on network security and computer forensics to better equip law enforcement and user security.
The work on distinguishability in quantum communication is supported by the National Sciences and Engineering Research Council (NSERC) of Canada.
Reference: A. R. Salehiyoun, M. Sharifi, O. Norouzi, A. Dutta, F. Di Maria, H. Zilouei, S. Mofatteh, “Dry anaerobic digestion of organic fraction of municipal solid waste in a vertical plug digester: Start-up procedures, digestate recirculation, organic loading rates, and energy balance analysis,” Biomass and Bioenergy, vol 193, 2025. Doi: 10.1016/j.biombioe.2024.107492