PhD student seeks to make drinking water treatment more sustainable

Growing up in a small neighbourhood in Cameroon, Maeva Che was well aware of the challenges of accessing clean drinking water. 

“Experiencing that exposure to water issues and challenges with sustainable access to safe drinking water ignited my interest in water treatment,” says Che, who is now a PhD student in the University of Toronto’s Faculty of Applied Science & Engineering.  

Her drive to improve water quality around the globe brought her to the faculty’s Drinking Water Research Group (DWRG), where she is researching innovative solutions to address local water issues.  

Working under the supervision of DWRG member Ron Hofmann, a professor in the department of civil and mineral engineering, Che’s research focuses on removing unpleasant taste and odour compounds in Ontario’s drinking water by promoting the biodegradation of these compounds through granular activated carbon (GAC) filtration. 

The project is supported by a five-year Natural Sciences and Engineering Research Council of Canada (NSERC) Alliance grant called “Advanced and Emerging Issues in Drinking Water Treatment.” 

GAC filtration is a water treatment process that uses granular activated carbon, which is made from organic materials that are high in carbon, such as wood, coal or coconut shells. These materials are heated in the absence of oxygen through a process known as pyrolysis and prompted chemically or physically to produce the activated carbon. The activation enhances the material’s adsorption properties, improving its ability to remove contaminants from water.  

GAC filtration is an effective treatment process, but its limited adsorptive capacity is exhausted after about three years in service, requiring replacement. For drinking water facilities, that’s both inconvenient and costly.  

Che is working on alternative ways to remove contaminants using GAC filtration – specifically through biodegradation. When the filtration has been in service for a while, there is the growth of micro-organisms on the GAC that can be useful for removing contaminants.   

“Think of biodegradation as the useful bacteria on the GAC feeding on the contaminants in the water, thereby removing them,” Che says. 

“If the GAC has enough good bacteria that is biodegrading the compounds, the GAC may not need to be replaced when its adsorptive capacity becomes exhausted. This can extend the filter’s lifetime, resulting in cost benefits for treatment utilities.” 

In other words, biodegradation can potentially enhance the performance of GAC filters. 

Che and the DWRG are planning to collaborate with water treatment plants to determine methods that can enhance the biodegradation of taste and odour compounds within their GAC filters.  

Currently in its initial phase, the project is taking place alongside the Peterborough Utilities Group’s drinking water treatment plant, where Che is conducting pilot-scale filtration studies with support from the Peterborough Utilities Commission. They plan to extend this research to other partner treatment plants in the future. 

Working with other water treatment plants across Ontario, Che will also assess the effectiveness of GAC filters in removing non-traditional taste and odour compounds that are not commonly monitored. 

To do this, she plans to evaluate filter performance for two common taste and odour compounds  (2-methylisoborneal and geosmin) and eight additional non-traditional compounds that can cause taste and odour. This involves collecting GAC and water samples from the plants and conducting lab-scale filtration tests known as mini-column tests. This test, developed by the DWRG, allows researchers to differentiate between adsorption and biodegradation in GAC filters, providing crucial insights into their performance. 

“Many plants are unaware of their filters’ performance for other compounds, aside from the two common ones, that also contribute to taste and odour events in water. Our project, therefore, plays a crucial role in expanding the understanding of this,” Che says. 

Project partners include the Ajax Water Supply Plant and the Barrie Surface Water Treatment Plant.  

The DWRG comprises about 30 graduate students, postdoctoral researchers, research managers and associates who collaborate with local, national and international industry and government organizations to address a wide range of projects related to municipal drinking water. 

Che credits her experience as a master’s student with the research group as a major factor in her decision to pursue a PhD at the university.  

“During my master’s degree with the DWRG, I worked on projects that improved drinking water quality, gaining hands-on experience at treatment plants. Seeing the results of my research reinforced my decision to pursue my PhD here,” Che says. 

Ultimately, Che hopes to make a significant impact in the field with the help of a supportive DWRG researchers and supervisors.  

“My goal is to continue researching and developing sustainable solutions for drinking water treatment that benefit communities in need.”