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UBC Theses and Dissertations

Treatment of the oil sands process-affected water using microbial degradation Chegounian, Parisa


Naphthenic acid fraction compounds (NAFCs) are highly recalcitrant contaminants of oil sands process-affected water (OSPW). Classic naphthenic acids (NAs), with an empirical formula of CcHhO2, have been determined as the most toxic NAFCs. The concentration of classic NAs in the OSPW collected for this study was determined as 28.2 mg/L using high-performance liquid chromatography (HPLC) Orbitrap mass spectrometry. An Innovation Ecosystem for the commercialization of engineered bioremediation platforms was defined and connected to a detailed risk framework including technological risks, regulatory risks, and risk perception. Using enrichment culture techniques with NAFCs as the only carbon source, seven distinct cultures were isolated from OSPW. NAs treatability study with the seven isolated cultures resulted in selecting four Pseudomonas cultures for further characterization. These four cultures were identified as Pseudomonas protegens, Pseudomonas putida, Pseudomonas stutzeri, and Pseudomonas sp. following the whole genome sequencing and assembly. A comparative genomic analysis of these cultures detected genomic islands and positively selected genes (PSGs). For the transcriptional response, P. protegens, P. putida, and a 1:1 co-culture of the isolates were examined in the presence of NAFCs, as the only carbon source. The RNA-Seq and HPLC-Orbitrap data were combined into custom Python scripts and revealed the identity of enzymes and pathways associated with different NAFC groups. Compared with individual cultures, co-cultures of these two isolates demonstrated a completely different degradation mechanism. Furthermore, the co-culture degraded a greater quantity of NAFCs (~30%) than pure cultures (~11%). A pilot-scale test was conducted in 5 m³ mesocosms with 1:1 co-culture of P. protegens and P. putida. Two experimental factors, aeration and inoculation, were tested with three replicates of each factor. Twelve mesocosms were divided into four groups: control, aeration, inoculation, and aeration and inoculation treatments. The genome-resolved metagenomics and metatranscriptomics analysis were performed to characterize the phylogenetic and metabolic diversity of OSPW. In general, the inoculated treatment demonstrated the most over-represented degradation pathways compared to the other two treatments. In the metatranscriptomic data, benzoate degradation and degradation of aromatic compounds pathways were only over-represented in inoculated and aerated treatments even though they were over-represented in all treatments in the metagenomic data.

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