AWWA Water Science Author Spotlight: Isobel DeMont

Having recently published an article in AWWA Water Science, Isobel DeMont answered questions from the publication's editor-in-chief, Kenneth L. Mercer, about the research.

Monitoring Natural Organic Matter in Drinking Water Treatment With Photoelectrochemical Oxygen Demand

Isobel DeMont, Lindsay E. Anderson, Jessica L. Bennett, Chrissa Sfynia, Paul Bjorndahl, Peter Jarvis, Amina K. Stoddart, and Graham A. Gagnon

I am a PhD candidate at the Center for Water Resources at Dalhousie University (Halifax, N.S.); my research focuses on advanced oxidation processes in drinking water applications. Specifically, I’m investigating the formation of disinfection byproducts by UV-LED light and chlorine. Last year, I also started working as an instructor at Dalhousie, teaching first-year engineering courses. In this new role, I am trying to enhance the hands-on learning experience for undergraduate students and bring the sustainable awareness I’ve adopted from my research into the classroom. It has been incredibly fun applying my passion for learning, which prompted me to pursue a PhD in the first place, to this new position.

At the Centre for Water Resources Studies, Isobel DeMont performs jar tests that were used to help local water utilities optimize their full-scale drinking water treatment operations.

Consequences of climate change have led to significant changes in surface water quality around the world. One observed trend is the increased presence of climate-driven micropollutants, such as toxins produced by algae species that thrive in warm waters. Many of these micropollutants are resistant to conventional drinking water treatment processes. One potential technology that has proved to be effective is advanced oxidation with UV-LED light and chlorine. The blast of high energy from the UV-LED light breaks apart chlorine molecules, forming highly reactive compounds called radicals. The radical reactions change the molecular structure of the micropollutants, making them nontoxic. While this is a great outcome, the radicals also form byproducts when they react with other, nontoxic, organic compounds in the water, and some of the byproducts pose public health risks. My research investigates how we can tailor treatment conditions (e.g., chlorine dose, amount of light, UV-LED wavelength, water pH) to ensure the toxic micropollutants are degraded while minimizing the formation of harmful byproducts.

Radicals formed during advanced oxidation with UV-LED and chlorine react not only with climate-driven micropollutants but also with other nontoxic organic material in the water sample. The reactions between radicals and organic material often change the form of organic material but don’t degrade it entirely such that the total organic content concentration is reduced. As such, organic-content, concentration-based methods for evaluating treatment performance often are not suitable for evaluating advanced oxidation treatment methods.

This problem prompted the research discussed in our AWWA Water Science article, which highlights the photoelectrochemical oxygen demand (peCOD) method. PeCOD is a novel method for quantifying changes in organic material caused by oxidation-based processes. The method measures the oxidizability of the organic material in a water sample, which essentially is a measure of its reactivity. In our article, the benefit of peCOD measurements was highlighted as we reported significant decreases in peCOD measurements following oxidation-based treatment processes, where concentration-based measurements showed no significant change. Tools like peCOD will be valuable in optimizing advanced oxidation processes, including UV-LED and chlorine, as they become more prominent in drinking water treatment.

This work is a continuation of previous research done in the CWRS by my co-supervisor, Dr. Amina Stoddart. She developed a method (ASTM International method D8084-17) for peCOD analysis in drinking water in 2017 and applied this method in Atlantic Canada drinking water treatment plants (https://doi.org/10.5942/jawwa.2014.106.0106). Dr. Stoddart's work was limited to conventional and biofiltration treatment processes and to Atlantic Canada source water. Our AWWA Water Science article expanded on her work by considering source waters across Atlantic Canada and the United Kingdom and also considered more advanced treatment processes (e.g., adsorption, advanced oxidation).

Isobel went on a desert safari in Dubai after attending the International Ultraviolet Association World Congress in 2024.

The biggest challenge I noticed was the geographic scope of the study. Collaborating with researchers from other universities was not something I had done before, so while it was fun, navigating that process and trying to make everything run as smoothly as possible for everyone was a learning experience for me.

After completing the research for the AWWA article and learning more about the peCOD method, I was prompted to investigate how certain chemical compounds, particularly ones that are being introduced through advanced oxidation processes, may interfere with peCOD measurements. The peCOD ASTM method states potential interferences from chloride, but I was curious about how some of the chemicals used strictly for lab-based experiments or measurements (e.g., radical quenching agents) may impact the peCOD reading, if at all. I’ve since begun experimenting with this research question and, luckily, none of my results have been shocking yet.

I mainly fill my free time with athletic endeavors. I train in Olympic-style weightlifting, which I really enjoy because there is no ceiling to your goals; you can always try to lift one more kilogram. I also like playing volleyball, pickleball, and tennis, and running outdoors. I enjoy sports because I can turn my brain off for a few hours and focus on one main goal. I am also fairly competitive, so competing in sports scratches that itch as well. When I can, I also like to travel. I went to Dubai last year for a conference, and it was the trip of a lifetime!

For me, the most exciting aspect of working in the water industry is being able to see the wide impact of my research. In my master's program, for example, I worked very closely with a local water utility, and some of my results were considered when altering treatment operations on the full-scale plant. Having my work help benefit hundreds of thousands of people was very cool.

I also find it exciting how the industry is constantly evolving. Every day, there are new challenges water engineers must address, and it constantly keeps us on our toes. This dynamic nature of the industry makes it impossible to be bored!

To learn more about Isobel's research, visit the article, available online at https://doi.org/10.1002/aws2.1378.