“One man’s trash is another’s treasure” is a well-worn phrase. At Queen’s Engineering, one scientist’s relentless pursuit of biowaste treatment is bringing the expression to life – and helping save our planet in the process.

“We can recover value-added products from our biowaste,” says Dr. Ehssan Koupaie, an assistant professor and researcher in Queen’s Department of Chemical Engineering.

His nearly 20-year academic journey has focused on environmental issues. From undergraduate studies in civil engineering at Isfahan University of Technology through advanced degrees in Tehran and British Columbia to postdoctoral works at Ryerson and the University of Toronto, Koupaie has seen his academic interests evolve from wastewater treatment to resource recovery from waste.

“It took me four years to realize that civil engineering is more than structural engineering,” he says of his early academic career. Courses in the environment and in wastewater treatment opened his eyes to the value of environmental engineering – thinking beyond structures to their impact, and “trying to protect both the environment and society,” he says.

Dr. Ehssan Koupaie

His PhD research refocused his energies on anaerobic digestion and the recovery of energy from organic waste, an area of research he has been developing to this day.

“At the University of British Columbia, I was first exposed to the idea that besides treating waste, we can recover value-added products,” he says of his PhD work at UBC supervised by Dr. Cigdem Eskicioglu, a renowned researcher in the area. That work honed in on one of the fundamental issues in the area of resource recovery from biowaste: energy inefficiency.

Before microorganisms can convert material like municipal sludge or animal manure into bioenergy, biofuels, or other value-added products, the solid waste must be broken down into smaller particles. Many facilities hasten this process through a technique called thermal hydrolysis, during which the waste is exposed to heat and pressure prior to anaerobic digestion. Pre-treating waste can be energy intensive though, often requiring as much or more energy than is ultimately recovered.

Working with an interdisciplinary team that included environmental engineers, electrical engineers and physicists, Koupaie formulated a novel method of solid waste pre-treatment called radio-frequency thermal hydrolysis. He and his colleagues demonstrated that heating the waste material using radio waves prior to anaerobic digestion resulted in a positive net energy balance.

“For the first time, we were able to spend less energy compared to the amount of energy you get at the end,” he said.

Subsequent work as a postdoctoral fellow at Ryerson and the University of Toronto allowed Koupaie to continue working on the problem of resource recovery from organic waste, including efforts to optimize waste fermentation and anaerobic digestion for the recovery of specific products, like biomethane, alcohols, and volatile fatty acids. Koupaie hopes that the processes can be tailored some day to meet the unique resource needs of different regions and industries.

“In Ontario, energy is relatively cheap, and using anaerobic digestion to produce biomethane does not make economic sense,” he says. If, however, the process could be tweaked to recover more products of greater local value, Koupaie surmises that it may become a more attractive proposition for the industry. That could make a huge difference for a province in dire need of waste management solutions; Ontario’s existing landfills are due to reach capacity within the next 15 years.

“The more we can recover value-added products, the more we are moving towards the circular, rather than the linear economy,” he said. 

Since joining Queen’s Engineering in July of 2020, Koupaie has been busy establishing a laboratory to continue his research into resource recovery, including a new process he’s been developing for the recovery of biopolymers from organic waste. He also hopes to secure industrial partners who can support the larger-scale application of the novel hydrolysis technique he developed during his PhD.

Professor Koupaie currently has two undergraduate researchers working in his lab, and will take on his first PhD student in May of this year. The students are a welcome presence, and an opportunity to share both research discoveries and ecological values with younger engineers. He hopes that this generation won’t have to wait four years, like he did, to learn about environmental engineering.

“One of my goals is to train the next generation of researchers and engineers,” he said, “so they have a better understanding of what’s going on in terms of environmental problems.”