Remediation of Oil Sand Process Waters Using a Combined Chemical and Biological Approach

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Production of bitumen and heavy oil from the Canadian oil sands is a major thrust in the national economy and is crucial for the global supply of energy. However, utilizing this valuable resource in an environmentally friendly and sustainable manner is critical. Oil sands processing generates waters contaminated with toxic naphthenic acids (NAs). Environmental regulations require oil sands process waters (OSPW) be retained on-site until they undergo proper treatment. The current practice of storage in tailing ponds and reliance on natural physicochemical and biological processes to remove NAs is not sustainable. This research will develop an innovative approach in which a chemical pretreatment step is used to break down the complex NA molecules into smaller molecules more suitable for biodegradation. These simpler molecules are then converted to harmless compounds through biodegradation in properly designed bioreactors. Four short-term objectives are to: 1) investigate chemical oxidation of surrogate NAs (individual molecules of different structures) and NAs in OSPW; 2) evaluate bioremediation of untreated and chemically treated OSPW in laboratory- and pilot-scale circulating packed-bed bioreactors under aerobic conditions; 3) investigate anaerobic biodegradation of surrogate NAs under denitrifying conditions; and 4) evaluate anaerobic biodegradation of NAs in untreated and chemically treated OSPW. The long-term objective of this research is to use the generated knowledge to develop an innovative chemical-biological technology for remediation of OSPW and contribute to addressing this critical environmental challenge facing the Canadian oil sands industry. Application of the developed technology will contribute to a safer and cleaner environment for all Canadians. Moreover, benefits will not be limited to the oil sands industry as proper modifications could make the technology applicable to the remediation of other polluted waters. Training of highly qualified personnel as part of this research will build capacity in Canadian universities and industry in support of Canada's leading role in energy development and environmental sustainability.