Graduate Exit Seminar - Lillian Daw Labus

Plan to join Lillian Daw Labus's graduate exit seminar on November 21, 2024, at 9:00 am in Kottman Hall, Room 200 or via Zoom. Lillian will present, "Nutrient and Dissolved Organic Matter Response to Harmful Algal Bloom Treatment by Ozone Nanobubbles, an Emerging Technology."

Abstract: Harmful algal blooms, driven by increased nutrients in aquatic systems, are a growing problem world-wide. While there are strategies to prevent and treat these bloom events, many of the methods are ineffective or can cause ecological harm. Thus, there is a need to explore new and alternative prevention and treatment methods for algal blooms. Based on technology used in drinking water treatment, nanobubble ozone technology (NBOT) is a new method under development for treating harmful algal blooms. However, before this new technology can be considered a viable option, it is important to understand proper dosage, as well as how it might affect other parts of the aquatic ecosystem. Nitrogen, phosphorus, and dissolved organic matter (DOM) are all important nutrients in the aquatic ecosystem and all have the potential to react with ozone and be released during algae death, so they could interfere with and be altered by NBOT treatment. To understand the response of nutrients and DOM after NBOT treatment, we performed a mesocosm study with water from Grand Lake St. Mary’s, which frequently experiences some of the worst harmful algal blooms in the country. The mesocosm trial included 4 different treatments (high, medium, and low doses of ozone nanobubbles, and oxygen nanobubbles) and untreated controls. We found that increasing doses of ozone resulted in larger and more rapid decreases in the cyanobacteria. As the ozone dose increased, more particulate nitrogen and phosphorus was converted to dissolved forms. The medium and high ozone doses resulted in an immediate increase in algal-sourced DOM after treatment which corresponded with evidence of cell lysis. DOM in the tanks treated with a low dose of ozone increased at a slower rate. Across all ozone doses, humic-like DOM demonstrated more reactivity with ozone than protein-like DOM, suggesting this portion of DOM is more likely to interfere with efficacy of treatment.

Advisor: Dr. Rachel Gabor