Pathogen Transport and Survival in Aquatic Environments and New Approaches for Water Quality Protection

Dr. Bahareh Asadishad, Department of Chemical Engineering McGill University

08 June 2015 at 10:30

Location: JHE 326H

The occurrence of microbial pathogens in drinking water sources is recognized as a significant threat to public health. A better understanding of the key processes governing the fate of microbial pathogens in groundwater aquifers can help mitigate the risk of drinking water contamination. The attachment of pathogens to aquifer surfaces and the inactivation of attached and suspended pathogens are key processes that attenuate the concentration of viable pathogens in potable water supplies. A fluorescence-based experimental technique was developed to evaluate the inactivation kinetics of pathogenic bacteria adhered onto a surface in an aqueous environment. The new method aimed to advance the understanding of bacterial adhesion by providing platforms that mimic the bacteria’s natural environment, whilst also enabling concurrent monitoring of bacterial viability. This method was used to characterize bacterial inactivation kinetics when attached to environmentally relevant surfaces such as metal oxides over a broad range of groundwater chemistries. Temperature is another key factor that affects bacterial survival and transport. Surface and near-surface soils in cold climate regions experience low temperature and freeze-thaw (FT) conditions in the winter and spring. Microorganisms that are of concern to groundwater quality may have the potential to survive low temperature and FT in the soil and aqueous environments. The effect of cold temperature and repeated FT on survival, transport and infectivity of selected Gram-negative and Gram-positive bacteria was investigated. Our findings demonstrate that bacteria exhibited greater retention onto aquifer grains after exposure to FT. Moreover, bacteria tend to survive for longer periods of time and may become more virulent at low temperature in higher ionic strength waters thereby posing a potential threat to drinking water supplies. Hence, the study of bacterial adhesion to surfaces and development of novel platforms for water quality monitoring and novel processes for water treatment constitute important research areas with global impact. New approaches are proposed to monitor water quality by introducing smart and responsive antimicrobial surfaces with the potential of rapid biodetection of pathogens. Hybrid materials combining antimicrobial and fouling-resistant properties by integrating biocides with stimuli-responsive polymers for the release of bacteria are proposed to transform filtration processes in water treatment. 

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