Aerobic biodegradation of cycloalkanes in non-aqueous extracted oil sands tailings

Management of growing volumes of fluid fine tailings (FFT) is a significant challenge for oil sands industry. A potential alternative non-aqueous solvent extraction (NAE) process uses cycloalkane solvent such as cyclohexane or cyclopentane with very little water and generates smaller volumes of ‘dry...

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Bibliographic Details
Published in:	Chemosphere (Oxford) Vol. 349; p. 140900
Main Authors:	Gjini, Luke, Kuznetsova, Alsu, Okpala, Gloria, Foght, Julia M., Ulrich, Ania, Siddique, Tariq
Format:	Journal Article
Language:	English
Published:	England Elsevier Ltd 01-02-2024
Subjects:	Biodegradation Cycloalkanes Hydrogenophaga Non-aqueous extraction solids Oil sands Rhodoferax Biodegradation Hydrogenophaga Oil sands Cycloalkanes Non-aqueous extraction solids Rhodoferax
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Summary:	Management of growing volumes of fluid fine tailings (FFT) is a significant challenge for oil sands industry. A potential alternative non-aqueous solvent extraction (NAE) process uses cycloalkane solvent such as cyclohexane or cyclopentane with very little water and generates smaller volumes of ‘dry’ solids (NAES) with residual solvent. Here we investigate remediation of NAES in a simulated bench-scale upland reclamation scenario. In the first study, microcosms with nutrient medium plus FFT as inoculum were amended with cyclohexane and incubated for ∼1 year, monitoring for cyclohexane biodegradation under aerobic conditions. Biodegradation of cyclohexane occurred under aerobic conditions with no metabolic intermediates detected. A second study using NAES mixed with FFT spiked with cyclohexane and cyclopentane, with or without additional nutrients (nitrogen and phosphorus), showed complete and rapid aerobic biodegradation of both cycloalkanes in NAES inoculated with FFT and supplemented with nutrients. 16S rRNA gene sequencing revealed dominance of Rhodoferax and members of Burkholderiaceae during aerobic cyclohexane biodegradation in FFT, and Hydrogenophaga, Acidovorax, Defluviimonas and members of Porticoccaceae during aerobic biodegradation of cyclohexane and cyclopentane in NAES inoculated with FFT and supplemented with nutrients. The findings indicate that biodegradation of cycloalkanes from NAES is possible under aerobic condition, which will contribute to the successful reclamation of oil sands tailings for land closure. [Display omitted] •Cycloalkanes were biodegraded under aerobic conditions in “dry” oil sands tailings.•Anaerobic fluid fine tailings used as inoculum provided microbes for aerobic biodegradation.•Higher abundance of Rhodoferax and Hydrogenophaga suggested their involvement in cycloalkane biodegradation.•Results suggest bioremediation of cycloalkane-contaminated wastes under upland reclamation.
ISSN:	0045-6535 1879-1298
DOI:	10.1016/j.chemosphere.2023.140900