Impacts of Geothermal Heating on Groundwater Quality and BTEX Biodegradation

Abstract

Benzene, toluene, ethylbenzene, and xylene (BTEX) are common groundwater contaminants that pose environmental and health risks. While bioremediation is a sustainable treatment method, low temperatures in Canada can limit microbial activity. This thesis investigates the coupling of bioremediation with geothermal heat pumps, as there is minimal research on the effects of geothermal heating on groundwater chemistry and microbial degradation in monocultures and a consortium. Laboratory experiments at 15, 28, and 40 °C evaluated BTEX degradation by Bacillus infantis, Microbacterium esteraromaticum, and a consortium. Groundwater parameters were monitored to assess temperature effects. A Triticum aestivum seed germination assay evaluated the soil toxicity post-treatment. Results showed that temperature enhanced microbial activity, with the consortium achieving 42% degradation at 28 °C. Remediated soils supported seed germination, though trace hydrocarbons remained bioavailable and reduced root growth. These findings emphasize integrating chemical and biological assessments to evaluate remediation effectiveness and support sustainable strategies for contaminated subsurface environments.