Study on Treatment of Oil Sands Process-Affected Water Using A Bioreactor Process Train

• Author / Creator

  Zhu, Lei

• With rapid development of Canadian Oil Sands industry, concerns about adverse impacts of oil sands process-affected water (OSPW) on aquatic resources are magnified. It has been found that biological process for removing organic chemicals in the oil industrial wastewater is environmentally friendly and economical. However, the application of conventional biological treatment to complex industrial wastewater has been hindered by the sensitivity of microorganisms to salinity and toxic recalcitrant organics, which are present in OSPW. In this work, a novel bioreactor process train was proposed, designed, fabricated and investigated for OSPW treatment.Firstly, a comprehensive literature review about bioreactors with an emphasis on their performance in treating recalcitrant industrial wastewaters was conducted to screen the potential ones for OSPW treatment. Two sets of bench scale experiments were performed on biodegradation of raw OSPW and HiPOx-treated OSPW to cultivate proper seed for inoculating selected bioreactors. The promising results from those batch studies suggested that bioreactors with proper seed had the capacity of removing the biodegradable organics in OSPW and chemical oxidation process was useful and necessary for OSPW treatment. Based on the literature review and bench scale studies, a novel bioreactor process train was proposed for treating OSPW, which was composed of moving bed biofilm reactor (MBBR) for removing easily biodegradable organics at first, ozonation followed for decomposing the remaining recalcitrant organics, membrane aerated biofilm reactor (MABR) for degradation of decomposed organics and adsorption column for the removal of residual organics in OSPW.Then, the selected bioreactors were designed, fabricated and continuously operated over 2 years. The entire operation was divided into different phases according to different influent composition and hydraulic retention time (HRT). To evaluate the performance of the bioreactor process train, chemical oxygen demand (COD) and acid extractable fraction (AEF) measured by Fourier transform infrared spectrum (FT-IR) were applied in this study. When the state of the bioreactor process train was stable, MBBR removed 23% of COD and 16% of AEF from OSPW at HRT of 3 days. With the utilized dose of 35 mg/L of ozone, the biodegradability of MBBR effluent increased. At the same HRT, reductions of 44% COD and 24% AEF in MABR were achieved. After adsorption column, the average COD and AEF in the effluent of the process train was 17 mg/L and 2.9 mg/L, respectively. Lastly, the demonstrated effective removal of chemical organics in OSPW present by this bioreactor process train inspired us to investigate the internal structure and microbial community of the biofilm inside each bioreactor by utilizing microsensor and molecular biological techniques together. It was found that nitrification and denitrification process existed in MBBR and MABR. Sulfate reduction process only existed in MABR biofilm, which was consistent with the H2S profile measured by H2S microsensor. The diversity of microbial community in the biofilm from MABR was higher than that in the biofilm from MBBR, which might explain the better performance on AEF removal in MABR. The influent composition and HRT were two main factors affecting the abundance and diversity of microbial communities inside bioreactors. Both bioreactors captured and enriched some specific microorganisms such as Pseudomonas, Falvobacterium and Rhodobacter, which showed great resistance to the harsh environment and the capability of degrading naphthenic acids in OSPW. Bioaugmentation happening inside MBBR and MABR made the biodegradation of recalcitrant organic chemicals in OSPW faster and reclamation of tailings pond promising.

• Subjects / Keywords

  • MABR
  • Bioreactor Process Train
  • Oil Sands Process-Affected Water
  • MBBR
  • Microsensor
  • Illumina Miseq Sequencing

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-wk9e-m684

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.