Biodegradation of Polyacrylamide in Oil Sands Tailings by Indigenous Microorganisms

• Author / Creator

  Batycky, Anya

• Hydrolyzed polyacrylamide (HPAM) is a common flocculant used in oil sands tailings dewatering technologies. Although HPAM is regularly used in tailings treatment and will eventually be incorporated into the reclaimed landscape of the oil sands, there are knowledge gaps surrounding the environment fate of HPAM, specifically its susceptibility to microbial degradation. Microcosm studies were established to evaluate the biodegradation of HPAM by indigenous oil sands tailings microorganisms under oxic, sulfate-reducing, and methanogenic conditions. Under each redox condition, the ability of microorganisms to use HPAM as a carbon and/or nitrogen source, or degrade HPAM through co-metabolism was investigated. Biodegradation was assessed using Size-Exclusion Chromatography, while the formation of hydrolytic ammonium indicated the use of HPAM as a nitrogen source.
  After 110 days, HPAM experienced the greatest biodegradation when provided as a co-substrate (99%) and nitrogen source (99%) under oxic conditions, with lower molecular weight oligomers (< 6000 g/mol) as biodegradation products. For anoxic conditions, HPAM biodegradation was observed when provided as a co-substrate (77% after 420 days) for sulfate-reducing conditions, and as a co-substrate (60% after 374 days) and nitrogen source (60% after 374 days) for methanogenic conditions. Under anoxic conditions, biodegradation produced oligomers with a molecular weight around 2-4 x 106 g/mol. An increase in ammonium was observed under all redox conditions. When HPAM was provided as a nitrogen source, this decreased the lag time of sulfate-reduction and methane production. HPAM biodegradation was not found to significantly increase acute toxicity towards Aliivibrio fischeri.
  Microbial communities identified in HPAM degrading cultures included Pseudomonadaceae, Flavobacteriaceae, Lentimicrobiaceae, and Acholeplasmataceae for oxic conditions, Methanosarcinaceae, Methanosaetaceae, Desulfuromonadia, Acholeplasmataceae, and Hydrogenophilaceae for sulfate-reducing conditions, and Methanosarcinaceae, Flavobacteriaceae, and Pseudomonadaceae for methanogenic conditions. This study demonstrated the conditions in which HPAM biodegradation could potentially occur in oil sands tailings systems or reclamation landscapes, and the bacteria and archaea involved.

• Subjects / Keywords

  • Polyacrylamide
  • Oil Sands Tailings
  • Biodegradation
  • PAM
  • HPAM
  • Reclamation
  • Methanogenesis
  • Sulfate Reduction
  • Toxicity

• Graduation date

  Spring 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-4bx7-dm18

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.