Biodegradation in oil sands process-affected water: A comprehensive laboratory analysis of the in situ biodegradation of dissolved organic acids

Evelyn Asiedu; Kankan Zhao; Mian Nabeel Anwar; Matthew Ross; Amy-Lynne Balaberda; Ania C Ulrich

doi:10.1016/j.chemosphere.2023.141018

Biodegradation in oil sands process-affected water: A comprehensive laboratory analysis of the in situ biodegradation of dissolved organic acids

Chemosphere. 2024 Feb:349:141018. doi: 10.1016/j.chemosphere.2023.141018. Epub 2023 Dec 21.

Authors

Evelyn Asiedu¹, Kankan Zhao², Mian Nabeel Anwar³, Matthew Ross⁴, Amy-Lynne Balaberda³, Ania C Ulrich⁵

Affiliations

¹ Division of Analytical & Environmental Toxicology, Department of Laboratory Medicine & Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada.
² Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
³ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada.
⁴ Department of Physical Sciences, MacEwan University, Edmonton, Alberta, T5J 2P2, Canada.
⁵ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada. Electronic address: aulrich@ualberta.ca.

PMID: 38141671
DOI: 10.1016/j.chemosphere.2023.141018

Abstract

Oil sands process-affected water (OSPW) is a by-product of the extraction of bitumen, and volumes of OSPW have accumulated across the Alberta oil sands region due to the governments zero-discharge policy. Some dissolved organics in OSPW, including toxic naphthenic acids (NAs), can be biodegraded in oxic conditions, thereby reducing the toxicity of OSPW. While there has been much focus on degradation of NAs, the biodegradation of other dissolved organic chemicals by endogenous organisms remains understudied. Here, using the HPLC-ultrahigh resolution Orbitrap mass spectrometry, we examined the microbial biodegradation of dissolved organic acids in OSPW. Non-targeted analysis enabled the estimation of biodegradation rates for unique heteroatomic chemical classes detected in negative ion mode. The microcosm experiments were conducted with and without nutrient supplementation, and the changes in the microbial community over time were investigated. Without added nutrients, internal standard-adjusted intensities of all organics, including NAs, were largely unchanged. The addition of nutrients increased the biodegradation rate of O₂^- and SO₂^- chemical classes. While anoxic biodegradation can occur in tailings ponds and end pit lakes, microbial community analyses confirmed that the presence of oxygen stimulated biodegradation of the OSPW samples studied. We detected several aerobic hydrocarbon-degrading microbes (e.g., Pseudomonas and Brevundimonas), and microbes capable of degrading sulfur-containing hydrocarbons (e.g., Microbacterium). Microbial community diversity decreased over time with nutrient addition. Overall, the results from this study indicate that toxic dissolved organics beyond NAs can be biodegraded by endogenous organisms in OSPW, but reaffirms that biological treatment strategies require careful consideration of how nutrients and dissolved oxygen may impact efficacy.

Keywords: Biodegradation; End pit lakes; Naphthenic acids; Oil sands; Ultrahigh resolution mass spectrometry.

MeSH terms

Carboxylic Acids / chemistry
Oil and Gas Fields*
Organic Chemicals
Oxygen / analysis
Water Pollutants, Chemical* / analysis

Substances

Water Pollutants, Chemical
Organic Chemicals
naphthenic acid
Carboxylic Acids
Oxygen