Gordon Chua1, Dean Quesnel1, Lindsay Clothier1, Thomas Oldenburg2, Stephen Larter2 and Lisa Gieg1
1Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
2PRG, Department of Geosciences, University of Calgary, Calgary, Alberta, Canada
The ability to mitigate toxicity of oil sands process-affected water (OSPW) is an important issue for effective tailings management in Alberta, Canada. OSPW toxicity has been linked to classical naphthenic acids (NAs), but the toxic contribution of other acid-extractable organics (AEOs) remains unknown. Here, we examine the potential for in situ bioremediation of OSPW AEOs by indigenous algae. Phosphate biostimulation was performed in OSPW to promote the growth of indigenous photosynthetic microorganisms and subsequent toxicity and chemical changes were determined. After 12 weeks, the AEO fraction of phosphatebiostimulated OSPW was significantly less toxic to the fission yeast Schizosaccharomyces pombe than unstimulated OSPW. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis of the AEO fraction in phosphate-biostimulated OSPW showed decreased levels of SO3 class compounds, including a subset that may represent linear arylsulfonates. A screen with S. pombe transcription factor mutant strains for growth sensitivity to the AEO fraction or sodium dodecylbenzenesulfonate revealed a mode of toxic action consistent with oxidative stress and detrimental effects on cellular membranes. Moreover, similar treatments with other OSPW samples indicated a loss of low molecular weight NAs and a significant decrease in acute toxicity of the OSPW by Microtox. The microbial community analysis suggests that a relationship between algae (Scenedesmus, Chlorella) and bacteria (Porphyrobacter, Planctomyces) may contribute to the reduction of NAs and toxicity. Altogether, this method could prove to be a feasible passive biotreatment option for partial remediation of large volumes of OSPW.
Quesnel et al. (2015) Biostimulation of Oil Sands Process-Affected Water with Phosphate Yields Removal of Sulfur-Containing Organics and Detoxification. Environ. Sci. Technol., in press.