Field, laboratory and life-cycle studies on the bioremediation of hydrocarbon-contaminated soils in cold and remote locations: Holistic approaches to the management of these soils in Northern Canada

Bioremediation was recently recognized as potentially the most cost-effective method of treating hydrocarbon (HC)-contaminated soils in cold regions. However, further research and development are required to optimize its application in such locations. Various aspects of cold climate bioremediation were investigated in the laboratory, under realistic field conditions in Northern Canada, and through modeling studies.;Bioremediation was suitable for the remediation of HC compounds with less than 16 carbon atoms (equivalent to the light HC fractions of diesel) at Ellesmere Island and in Labrador. Weathered high-molecular weight HCs (with more than 16 carbon atoms) were recalcitrant to bioremediation. The low temperatures and dry conditions exacerbated recalcitrance. The reduction of the concentration of those HCs may be very challenging in the North with simple bioremediation systems.;Extensive biodegradation was measured in experiments. However, volatilization played an important role in removing HC compounds that are usually considered not-readily volatile. Volatilization was likely predominant in the field, due to suboptimal conditions for microbial activity. Humidifying the air in a heated and aerated biopile system enhanced biodegradation and decreased volatilization. Increasing the aeration rate in bench-scale bioreactors simulating a biopile system stimulated microbial activity but resulted in high volatilization rates.;Soil treatability methodologies (18 kg bioreactors and 50 g microcosms) were tested in the laboratory. These methods better predicted the potential for bioremediation of the soils than the radioactive surrogate method that is widely used by site remediation practitioners.;The reduction of total HC and HC carbon ranges was investigated through gas chromatography/flame ionization detection (GC/FlD). HC removal processes (biodegradation and volatilization) were investigated with direct (GC/FID) and indirect (soil respiration) measurements.;The environmental cost of remediation of contaminated sites at a remote Northern location, an aspect never explored before, was investigated through life cycle assessment (LCA). When taking into account the overall environmental burden of remediation activities, on-site bioremediation was the preferred clean-up approach. The LCA demonstrated that the environmental cost of remediation should be an integral part of the design phase of remediation project and that the protection of the local environment should be balanced with that of the global environment during such projects.;KEYWORDS: Bioremediation, Petroleum Hydrocarbons, Biodegradation, Volatilization, North, Arctic, Landfarm, Biopile, Solid-Phase Bioreactor, Life Cycle Analysis, Life Cycle Assessment, LCA, Treatability Studies, Contaminated Soil, Contaminated Sites, Remediation.