Speaker: Dr. Elodie Passeport, Associate Professor, Department of Civil & Mineral Engineering, University of Toronto

Title: “Processes governing the fate of pharmaceuticals and personal care products in constructed wetland systems”

Date: April 25th, 2:30-3:30 pm

Location: Rm. 225, Mitchell Hall

 

Abstract

Thousands of chemicals end up in aquatic environments where they threaten the health of humans and ecosystems. One way to buffer their transport is to use passive water treatment systems such as constructed wetlands, lagoons, and bioretention cells. In this talk, I will go over a few examples of the performance of such systems and the reaction mechanisms that govern contaminant fate in passive water treatment systems. In particular, I will present the phototransformation potential of triclosan, an anti-microbial agent, in wetland systems. The role of nitrate concentration, pH, and dissolved organic carbon concentration on triclosan phototransformation rates and the production of transformation products will be discussed. I will also show our results on the potential of two freshwater algae species, Chlorella vulgaris and Scenedesmus obliquus, for the transformation of selected pharmaceuticals and personal care products. Experiments were conducted with lab-scale reactors including multiple control conditions. Four pharmaceuticals and personal care products, i.e., triclosan, ibuprofen, carbamazepine, and gemfibrozil were studied. Transformation products were searched for via liquid chromatography high resolution mass spectrometry (Orbitrap). The results demonstrated the direct role of algae in the biotransformation of ibuprofen and triclosan, as well as that of the original field water microbes. Triclosan was also phototransformed, whereas no change in concentration of carbamazepine and gemfibrozil was observed. Synergistic interactions between the algae (and its microbiome) and the water microbes were found. This research shows that a careful characterization of internal biogeochemical and hydrological processes of passive water treatment systems is critical to develop efficient and robust design and management strategies.

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