Enhanced bioremediation of nutrient contaminated groundwater

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In Manitoba approximately 25% of shallow rural domestic water wells contained nitrate exceeding the drinking water standards (Frost 2006). Remediation techniques that can address nutrient contaminated soil and groundwater beneath bulk fertilizer and nutrient storage facilities are crucial for healthy drinking water in rural areas. One such technique, enhanced bioremediation, includes the addition of a carbon source, electron acceptors, and/or macro or micro nutrients to promote nitrate degradation by native microbial populations (ITRC 2000). The benefit of enhanced bioremediation includes the promotion of the natural microbial population, limited disturbance of the land, and a sustainable green solution to remediation. This research collaboration between the University of Manitoba and Amec Foster Wheeler examines ethanol as a carbon source for improving nitrate denitrification capacity. Ethanol has shown promise for high denitrification rates in colder climates, with soil columns showing 95% reduction within weeks (Martin et al. 2009; Edwards et al. 2007). As part of this research, soil and groundwater from a nutrient contaminated fertilizer storage facility will be used to create microcosms to evaluate the nitrate removal rates under cold climate conditions. Microbial populations will be evaluated between the different treatments to determine the effect of the ethanol injections on microbial growth/metabolism. A laboratory soil column test will examine the movement of ethanol to understand and predict the movement through the aquifer. These results will form the basis for a numerical flow model of the site for the future implementation of a field-scale remediation treatment plan. This research is critical to understand the microbial and aquifer material response to ethanol addition and help develop cost effective and timely solution for nitrate remediation.