Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 2, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Food Science and Technology, Department of Agricultural, Food, and Nutritional Science, University of Alberta Includes bibliographical references.

Extraction of bitumen from Alberta oil sands produces 2 to 4 barrels of aqueous tailings per barrel of crude oil. Oil sands process water (OSPW) contains naphthenic acids (NAs), a complex mixture of carboxylic acids of the form CnH2n+ZOx that are persistent and toxic to aquatic organisms. Previous studies have demonstrated that aerobic biodegradation reduces NA concentrations and OSPW toxicity; however, treatment times are long. The objective of this study was to evaluate the feasibility of an immobilized soil bioreactor (ISBR) for treatment of NAs in OSPW and to determine the role of ammonium and ammonium oxidizing bacteria (AOB) in NA removal. ISBRs have been used to successfully remediate water contaminated with pollutants such as pentachlorophenol and petroleum hydrocarbons. A system of two ISBRs was operated continuously for over 2 years with OSPW as the sole source of carbon. Removal levels of 30-40% were consistently achieved at a residence time of 7 days, a significant improvement compared to half-lives of 44 to 240 days reported in the literature. However, similar to biodegradation experiments in the literature, a significant portion (~60%) of the NAs was not degraded. The role of AOB in NA removal was investigated by decreasing ammonium concentration and inhibiting AOB activity with allylthiourea, neither of which significantly affected removal, indicating that AOB did not enhance NA removal. Furthermore, high AOB populations actually inhibited the removal of a simple NA surrogate. Therefore, a moderate ammonium concentration of 0.3 g/L is recommended. NA degradation occurred with nitrate as the sole nitrogen source, however, removal levels were lower than those achieved with ammonium. Exploratory studies involving ozonation or biostimulation were conducted with the aim of increasing NA removal. Ozonation decreased NA concentration by 94% and total organic carbon (TOC) by 6%. Subsequent ISBR treatment removed ~30% of the remaining TOC. Addition of a NA surrogate increased heterotrophic NA-degrading populations due to the increase in available carbon, resulting in a significant increase in NA removal levels. However, use of a surrogate may result in a population that is only adapted to degradation of the NA surrogate. / Thesis (Master, Chemical Engineering) -- Queen's University, 2013-06-20 14:53:47.498

Oil sands operators are being faced with the challenge of reclaiming the large volumes of slurry tailings created during oil sands processing. New regulations mandate that operators must minimize fluid tailings by capturing fines in dedicated disposal areas, leading to a ‘trafficable’ or solid deposit. Adding a polyacrylamide polymer to the tailings and thinly spreading them over a sloped disposal area (a process developed by Shell Canada Energy known as the atmospheric fines drying or AFD process) has been shown to enhance the dewatering of tailings which leads to a dry deposit at a much faster rate than traditional methods. Hydroponic experiments using the emergent aquatic macrophytes cattail (Typha latifolia L.) and common reed (Phragmites australis (Cav.) Trin. ex Steud.) were conducted to investigate the phytotoxicity of waters formed during AFD processing. The phytotoxicity of AFD release waters was compared to the phytotoxicity of traditional mature fine tailings (MFT) reclaim water through the monitoring of plant water uptake and whole plant fresh weight over the course of the experiment. It was found that there are no significant differences between the phytotoxicity observed in the MFT and AFD treatments and it was also found that spring runoff melt water from the AFD deposits is less phytotoxic than the original release water. Two additional hydroponic studies using cattail and common reed were also conducted. The first examined the phytotoxic effects attributable solely to the naphthenic acids isolated from Shell’s Muskeg River Mine tailings, and the second evaluated the phytotoxic effects of amending mature fine tailings with gypsum. It was found that the gypsum amended tailings caused greater phytotoxicity in cattail and common reed than tailings without gypsum added. Furthermore, both species were tolerant to growing in nutrient media spiked with naphthenic acids (40 mg/L). The phytotoxicity experiments conducted also demonstrated that common reed is consistently more tolerant to growing in water associated with oil sands tailings and is therefore the more appropriate choice for use in reclamation strategies involving wetland plants. Mass spectrometry was used to determine the naphthenic acid molecular profiles for Shell oil sands tailings. Using low resolution mass spectrometry, no detectable features or changes to the composition of naphthenic acids attributable to Shell processing were found. High-resolution mass spectrometry provided insight into possible plant mediated changes and biodegradation of naphthenic acids. It appears as though, to some extent, cattail is able to dissipate naphthenic acids, which could explain the susceptibility of cattail to the phytotoxic effects of naphthenic acids. Further research is required to determine whether the changes observed in the naphthenic acid mixture are due to microbial degradation and/or a phytotoxic response of the plants studied.

This thesis presents the study of biodegradation factors of a candidate naphthenic acid compound, the trans isomer of 4-methyl-1-cyclohexane carboxylic acid (trans-4MCHCA). Low molecular weight components of naphthenic acids such as trans-4MCHCA are known to be toxic in aquatic environments and there is a need to better understand the factors controlling the kinetics of their biodegradation. In this study, a relatively low molecular weight naphthenic acid compound and a microbial culture developed in our laboratory (primarily Alcaligenes paradoxus and Pseudomonas aeruginosa) were used to study the biodegradation of this candidate naphthenic acid. The purpose of the research was to evaluate the kinetic parameters and model the biodegradation of this compound in three bioreactor systems: batch reactors, a continuously stirred tank reactor and immobilized cell reactors. <p>In batch reactors, the maximum specific growth rate (0.52±0.04 d-1) of the consortium at 23oC and neutral pH was not highly variable over various initial substrate concentrations (50 to 750 mg/L). Batch experiments indicated that biodegradation can be achieved at low temperatures; however, the biodegradation rate at 4oC was only 22% of that at room temperature (23oC). Biodegradation at various pH values indicated a maximum specific growth rate of 1.69±0.40 d-1 and yield (0.41±0.06 mg/mg) at a pH of 10. <p>Study of the candidate substrate using a continuously stirred tank reactor and the microbial culture developed in the batch experimentations revealed that the kinetics of the candidate naphthenic acid are best described by the Monod expression with a maximum specific growth rate of 1.74±0.004 d-1 and a half saturation constant of 363±17 mg/L. The continuously stirred tank reactor achieved a maximum reaction rate of 230 mg/(L∙d) at a residence time of 1.6 d-1 (39 h).<p>Two high porosity immobilized cell reactors operating continuously over three months were found to consume trans-4MCHCA at a rate almost two orders of magnitude higher than a continuously stirred tank reactor. The immobilized cell systems attained a maximum reaction rate of 22,000 mg/(L∙d) at a residence time of 16 minutes. High porosity immobilized cell reactors were shown to effectively remove a single naphthenic acid substrate in continuously fed operation to dilution rates of 90 d-1. A plug flow model best represented the degradation in the immobilized cell systems and was demonstrated to be a useful tool for studying the effects of parameter variation and prediction of reactor performance. This work highlights the potential of augmented bioremediation systems for the degradation of naphthenic acids.

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil, and predominantly obtained as the by-product of petroleum refining with variable composition and ingredients. Naphthenic acids are composed of alkyl-substituted cycloaliphatic carboxylic acids, with smaller amounts of acyclic aliphatic acids. Naphthenic acids become a significant part of the tailings pond water (TPW) after separation from oil sands material. NAs are soluble in water and are concentrated in TPW as a result of caustic oil sands extraction processes. Tailings ponds near the Athabasca oil sands region near Fort McMurray, Alberta, Canada are contaminated with a variety of toxic organic compounds released in industrial effluent from the oil extraction processes. NAs are among the major water contaminants in those regions because of their toxicity and environmental recalcitrance. They may enter surface water systems due to erosion of riverbank oil sands deposits and through groundwater mixing. Significant environmental and regulatory attention has been focused on the naphthenic acids fraction of oil sands material to address these challenges and potential hazards. Biological, chemical, and photolytic treatments of water contaminated with NAs have been studied, but are either time consuming or involve significant capital investment. There is a growing need to develop more efficient and cost-effective treatment methods. Based on existing literature, microwave and photocatalysis for degradation of naphthenic acids in water may be one solution. A knowledge gap exists in determining the effect of microwave energy and/or photocatalysis on the rate and extent of NAs degradation in contaminated water.<p> Part of this work included evaluation of the physical and chemical properties of NAs. Dielectric properties, important for designing a microwave system, were investigated. Effects of temperature, concentration, and frequency of microwaves on the dielectric properties of NA-water mixtures were studied and were used in designing the treatment systems for NAs. Three laboratory scale systems, (1) photocatalysis, (2) microwave, and (3) microwave assisted photocatalysis systems were designed and developed. Experiments were conducted to determine the NA degradation efficiency of these systems for both commercially available Fluka NAs and those extracted from oil sand process water (OSPW). Effects of water source (deionised and river water) and use of TiO2 catalyst in the degradation process, were also investigated. Degradation kinetics for total NAs as well as individual z-family were calculated.<p> Results show that the three developed treatment systems were able to degrade NAs at a faster rate than the methods reported to date. The concentration of higher molecular weight NAs (z = -4 to -12) decreased more significantly than the lower molecular weight NAs in all the three treatment systems. Toxicity assessments of the NAs samples before and after treatment indicated that photocatalysis and microwave assisted photocatalysis systems decreased the toxicity of Fluka and OSPW NAs completely (up to 5 min IC50 v/v > 90%). The microwave system reduced the toxicity of water containing Fluka NAs from high (5 min IC50 v/v = 15.85%) to moderate (5 min IC50 v/v = 36.45%) toxicity. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.<p> Microwave-assisted photocatalysis was the most rapid degradation system for OSPW NA extracts in water with a half-life of 0.56 h in the presence of TiO2. The microwave system degraded OSPW NAs in water at a more moderate half-life of 3.32 h. The photocatalysis system was the slowest with a half-life of 3.99 h under similar conditions.<p> High and ultra high resolution analysis of NA sample, estimations of cost and further efficiency related research of the developed systems to treat water with microbial load along with chemical contaminants are recommended for future work to further validate these treatment systems.

Oil sands mining operations in northeastern Alberta are rapidly expanding. Upgrading and extracting the bitumen from the sand requires large volumes of water generating large quantities of oil sands process water/materials (OSPM) which is high in organic content. Some of the major organic components found in OSPM include unrecovered bitumen, polycyclic aromatic compounds (PACs), naphthenic acids (NAs) and humic acids. Concerns of acute and chronic toxicity resulting from OSPM have led to provincial legislation preventing the discharge of OSPM into local water and mandating the reclamation of areas affected by oil sands mining. To date, OSPM is stored on lease in settling basins while the mining companies evaluate reclamation strategies. One of the reclamation strategies involves the use of wetlands constructed with differing amounts of OSPM and organic amendments such as peat. Currently, numerous wetlands, both natural and constructed, are present on oil sands leases. To determine the sustainability of these wetlands for reclamation, the assimilation and flow of carbon and nitrogen within the systems need to be defined. Stable isotope analysis can enhance this understanding. To effectively use stable isotopes in the field, there is the need to determine the changes in stable isotope values occurring from the microbial degradation of organic components such as NAs which contribute a significant portion to the dissolved organic carbon (DOC) in reclamation sites. This study examined the microbial degradation of commercial and oil sands derived NAs by oil sands derived microbial cultures. Changes in stable isotopes values in the biomass (δ13C, δ15N), DOC and dissolved inorganic carbon (DIC) (δ13C) arising from degradation of the DOC were tracked in both static and semi-continuous tests. Utilization of commercial and oil sands derived NAs resulted in minimal change of the DOC stable isotope values. The biomass was 13C enriched for both the commercial (0.3 to 2.9 per mil (‰)) and oil sands derived NAs (3.7 to 8.5 ‰) relative to the DOC stable isotope values. DIC stable isotope values showed higher variability (-5 to +5.5 ‰). The semi-continuous tests showed biomass that was 15N enriched (3.8 to 8.4 ‰) with the assimilation of ammonium. Isotope trends established in the laboratory study provide further understanding into assimilation of carbon and nitrogen compounds in the field. DOC and DIC concentration and carbon stable isotope values were determined for water sampled from 13 oil sands aquatic reclamation sites varying in age, construction and organic material. Both DOC and DIC concentrations were elevated in OSPM affected sites, by an average of 40 mg/L for DOC and 83 mg/L for DIC concentrations. DOC concentrations were also elevated by approximately 10 mg/L at high organic sites. δ13C DOC values were slightly 13C enriched in young sites: 0.6 ‰ compared to δ13C DOC values at the mature sites. Also, from June to July 13C enrichment (0.3 to 1.9 ‰) of the DOC for all sites was seen. Corresponding with the enrichment seen in the DOC, 13C depletion (-8.8 to -0.3 ‰) of the DIC was seen for most sites from June to July. The trends seen from June to July may be a result of the release of readily degradable organics from the spring thaw stimulating the microbial community. The baseline values determined for DOC and DIC may assist future field food web studies.

Oil sands mining operations in northeastern Alberta are rapidly expanding. Upgrading and extracting the bitumen from the sand requires large volumes of water generating large quantities of oil sands process water/materials (OSPM) which is high in organic content. Some of the major organic components found in OSPM include unrecovered bitumen, polycyclic aromatic compounds (PACs), naphthenic acids (NAs) and humic acids. Concerns of acute and chronic toxicity resulting from OSPM have led to provincial legislation preventing the discharge of OSPM into local water and mandating the reclamation of areas affected by oil sands mining. To date, OSPM is stored on lease in settling basins while the mining companies evaluate reclamation strategies. One of the reclamation strategies involves the use of wetlands constructed with differing amounts of OSPM and organic amendments such as peat. Currently, numerous wetlands, both natural and constructed, are present on oil sands leases. To determine the sustainability of these wetlands for reclamation, the assimilation and flow of carbon and nitrogen within the systems need to be defined. Stable isotope analysis can enhance this understanding. To effectively use stable isotopes in the field, there is the need to determine the changes in stable isotope values occurring from the microbial degradation of organic components such as NAs which contribute a significant portion to the dissolved organic carbon (DOC) in reclamation sites. This study examined the microbial degradation of commercial and oil sands derived NAs by oil sands derived microbial cultures. Changes in stable isotopes values in the biomass (δ13C, δ15N), DOC and dissolved inorganic carbon (DIC) (δ13C) arising from degradation of the DOC were tracked in both static and semi-continuous tests. Utilization of commercial and oil sands derived NAs resulted in minimal change of the DOC stable isotope values. The biomass was 13C enriched for both the commercial (0.3 to 2.9 per mil (‰)) and oil sands derived NAs (3.7 to 8.5 ‰) relative to the DOC stable isotope values. DIC stable isotope values showed higher variability (-5 to +5.5 ‰). The semi-continuous tests showed biomass that was 15N enriched (3.8 to 8.4 ‰) with the assimilation of ammonium. Isotope trends established in the laboratory study provide further understanding into assimilation of carbon and nitrogen compounds in the field. DOC and DIC concentration and carbon stable isotope values were determined for water sampled from 13 oil sands aquatic reclamation sites varying in age, construction and organic material. Both DOC and DIC concentrations were elevated in OSPM affected sites, by an average of 40 mg/L for DOC and 83 mg/L for DIC concentrations. DOC concentrations were also elevated by approximately 10 mg/L at high organic sites. δ13C DOC values were slightly 13C enriched in young sites: 0.6 ‰ compared to δ13C DOC values at the mature sites. Also, from June to July 13C enrichment (0.3 to 1.9 ‰) of the DOC for all sites was seen. Corresponding with the enrichment seen in the DOC, 13C depletion (-8.8 to -0.3 ‰) of the DIC was seen for most sites from June to July. The trends seen from June to July may be a result of the release of readily degradable organics from the spring thaw stimulating the microbial community. The baseline values determined for DOC and DIC may assist future field food web studies.

This thesis presents the study of biodegradation factors of a candidate naphthenic acid compound, the trans isomer of 4-methyl-1-cyclohexane carboxylic acid (trans-4MCHCA). Low molecular weight components of naphthenic acids such as trans-4MCHCA are known to be toxic in aquatic environments and there is a need to better understand the factors controlling the kinetics of their biodegradation. In this study, a relatively low molecular weight naphthenic acid compound and a microbial culture developed in our laboratory (primarily Alcaligenes paradoxus and Pseudomonas aeruginosa) were used to study the biodegradation of this candidate naphthenic acid. The purpose of the research was to evaluate the kinetic parameters and model the biodegradation of this compound in three bioreactor systems: batch reactors, a continuously stirred tank reactor and immobilized cell reactors. <p>In batch reactors, the maximum specific growth rate (0.52±0.04 d-1) of the consortium at 23oC and neutral pH was not highly variable over various initial substrate concentrations (50 to 750 mg/L). Batch experiments indicated that biodegradation can be achieved at low temperatures; however, the biodegradation rate at 4oC was only 22% of that at room temperature (23oC). Biodegradation at various pH values indicated a maximum specific growth rate of 1.69±0.40 d-1 and yield (0.41±0.06 mg/mg) at a pH of 10. <p>Study of the candidate substrate using a continuously stirred tank reactor and the microbial culture developed in the batch experimentations revealed that the kinetics of the candidate naphthenic acid are best described by the Monod expression with a maximum specific growth rate of 1.74±0.004 d-1 and a half saturation constant of 363±17 mg/L. The continuously stirred tank reactor achieved a maximum reaction rate of 230 mg/(L∙d) at a residence time of 1.6 d-1 (39 h).<p>Two high porosity immobilized cell reactors operating continuously over three months were found to consume trans-4MCHCA at a rate almost two orders of magnitude higher than a continuously stirred tank reactor. The immobilized cell systems attained a maximum reaction rate of 22,000 mg/(L∙d) at a residence time of 16 minutes. High porosity immobilized cell reactors were shown to effectively remove a single naphthenic acid substrate in continuously fed operation to dilution rates of 90 d-1. A plug flow model best represented the degradation in the immobilized cell systems and was demonstrated to be a useful tool for studying the effects of parameter variation and prediction of reactor performance. This work highlights the potential of augmented bioremediation systems for the degradation of naphthenic acids.

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil, and predominantly obtained as the by-product of petroleum refining with variable composition and ingredients. Naphthenic acids are composed of alkyl-substituted cycloaliphatic carboxylic acids, with smaller amounts of acyclic aliphatic acids. Naphthenic acids become a significant part of the tailings pond water (TPW) after separation from oil sands material. NAs are soluble in water and are concentrated in TPW as a result of caustic oil sands extraction processes. Tailings ponds near the Athabasca oil sands region near Fort McMurray, Alberta, Canada are contaminated with a variety of toxic organic compounds released in industrial effluent from the oil extraction processes. NAs are among the major water contaminants in those regions because of their toxicity and environmental recalcitrance. They may enter surface water systems due to erosion of riverbank oil sands deposits and through groundwater mixing. Significant environmental and regulatory attention has been focused on the naphthenic acids fraction of oil sands material to address these challenges and potential hazards. Biological, chemical, and photolytic treatments of water contaminated with NAs have been studied, but are either time consuming or involve significant capital investment. There is a growing need to develop more efficient and cost-effective treatment methods. Based on existing literature, microwave and photocatalysis for degradation of naphthenic acids in water may be one solution. A knowledge gap exists in determining the effect of microwave energy and/or photocatalysis on the rate and extent of NAs degradation in contaminated water.<p> Part of this work included evaluation of the physical and chemical properties of NAs. Dielectric properties, important for designing a microwave system, were investigated. Effects of temperature, concentration, and frequency of microwaves on the dielectric properties of NA-water mixtures were studied and were used in designing the treatment systems for NAs. Three laboratory scale systems, (1) photocatalysis, (2) microwave, and (3) microwave assisted photocatalysis systems were designed and developed. Experiments were conducted to determine the NA degradation efficiency of these systems for both commercially available Fluka NAs and those extracted from oil sand process water (OSPW). Effects of water source (deionised and river water) and use of TiO2 catalyst in the degradation process, were also investigated. Degradation kinetics for total NAs as well as individual z-family were calculated.<p> Results show that the three developed treatment systems were able to degrade NAs at a faster rate than the methods reported to date. The concentration of higher molecular weight NAs (z = -4 to -12) decreased more significantly than the lower molecular weight NAs in all the three treatment systems. Toxicity assessments of the NAs samples before and after treatment indicated that photocatalysis and microwave assisted photocatalysis systems decreased the toxicity of Fluka and OSPW NAs completely (up to 5 min IC50 v/v > 90%). The microwave system reduced the toxicity of water containing Fluka NAs from high (5 min IC50 v/v = 15.85%) to moderate (5 min IC50 v/v = 36.45%) toxicity. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.<p> Microwave-assisted photocatalysis was the most rapid degradation system for OSPW NA extracts in water with a half-life of 0.56 h in the presence of TiO2. The microwave system degraded OSPW NAs in water at a more moderate half-life of 3.32 h. The photocatalysis system was the slowest with a half-life of 3.99 h under similar conditions.<p> High and ultra high resolution analysis of NA sample, estimations of cost and further efficiency related research of the developed systems to treat water with microbial load along with chemical contaminants are recommended for future work to further validate these treatment systems.

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