2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference


Title
Mineralization pathways and kinetics of degradation of emerging contaminants as mixtures using UV/H2O2

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Author(s)
Mr. Jordan Hollman, University of Calgary (Presenter)
Dr. John Albino Dominic, University of Calgary
Dr. Gopal Achari, University of Calgary
Dr. Joo-Hwa Tay, University of Calgary
Abstract

The removal of pharmaceuticals from water and wastewater is an emerging concern due to a myriad of potential negative impacts posed on ecosystem and human health. A need exists to advance current wastewater/water treatment technologies to remove pharmaceuticals from water, along with a more robust understanding of the underlying chemistry of the processes. Amongst existing technologies, advanced oxidation processes (AOPs) have very high potential as they can degrade pharmaceuticals without creating additional waste streams. AOPs produce highly reactive hydroxy radicals which are non-specific in attach and can degrade a large variety of pollutants including pharmaceuticals. UV/H2O2 was the AOP used in this study as it could be implemented into existing wastewater treatment plants with minimal modification. The work presented here focused on degradation of four pharmaceuticals in a mixture: sulfamethoxazole (an antibiotic), venlafaxine (an antidepressant), carbamazepine (an anticonvulsant) and fluoxetine (an antidepressant) using UV/H2O2. Working with mixtures is a frequently understudied aspect of research on micropollutants but is essential for a working full-scale process as individual compounds are never found in isolation in water or wastewater. Degradation of a single compound by UV/H2O2 in comparison with mixture of compounds showed a significantly reduced rate of degradation, indicating that the presence of co-contaminants can be a significant limiting factor in degradation. The degradation of all four compounds was observed to follow pseudo first order kinetics with rates varying between each compound. The molecular structure and functional groups present in each pharmaceutical compound play a major role in susceptibility of each compound for degradation by hydroxyl radicals. Each reaction was studied in detail to make a prediction of the most likely degradation pathway for each compound. Additionally, a parametric study of H2O2 dose was conducted on the pharmaceutical mixture, which indicated that increasing H2O2 dosage can increase degradation rate. However, at higher H2O2 doses, diminished returns on degradation rate are gained per mass of H2O2, making higher H2O2 dosages less economical for large scale application.