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Karsten Liber - One of the best experts on this subject based on the ideXlab platform.
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Food web structure in Oil Sands reclaimed wetlands
Ecological Applications, 2013Co-Authors: K. E. Kovalenko, A. L. Foote, K. R. Frederick, J. M.gardner Costa, Andrea J. Farwell, D. G. Dixon, C. Daly, K. Kennedy, Jan J C Ciborowski, Karsten LiberAbstract:Boreal wetlands play an important role in global carbon balance. However, their ecosystem function is threatened by direct anthropogenic disturbance and climate change. Oil Sands surface mining in the boreal regions of Western Canada denudes tracts of land of organic materials, leaves large areas in need of reclamation, and generates considerable quantities of extraction process-affected materials. Knowledge and validation of reclamation techniques that lead to self-sustaining wetlands has lagged behind development of protocols for reclaiming terrestrial systems. It is important to know whether wetlands reclaimed with Oil Sands process materials can be restored to levels equivalent to their original ecosystem function. We approached this question by assessing carbon flows and food web structure in naturally formed and Oil Sands-affected wetlands constructed in 1970-2004 in the postmining landscape. We evaluated whether a prescribed reclamation strategy, involving organic matter amendment, accelerated reclaimed wetland development, leading to wetlands that were more similar to their natural marsh counterparts than wetlands that were not supplemented with organic matter. We measured compartment standing stocks for bacterioplankton, microbial biofilm, macrophytes, detritus, and zoobenthos; concentrations of dissolved organic carbon and residual naphthenic acids; and microbial production, gas fluxes, and aquatic-terrestrial exports (i.e., aquatic insect emergence). The total biomass of several biotic compartments differed significantly between Oil Sands and reference wetlands. Submerged macrophyte biomass, macroinvertebrate trophic diversity, and predator biomass and richness were lower in Oil Sands-affected wetlands than in reference wetlands. There was insufficient evidence to conclude that wetland age and wetland amendment with peat-mineral mix mitigate effects of Oil Sands waste materials on the fully aquatic biota. Although high variability was observed within most compartments, our data show that 20-year-old wetlands containing Oil Sands material have not yet reached the same level of function as their reference counterparts.
Dwayne D. Tannant - One of the best experts on this subject based on the ideXlab platform.
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Numerical and experimental study of wedge penetration into Oil Sands
Cim Bulletin, 2020Co-Authors: Dwayne D. Tannant, Caigen WangAbstract:An experimental and numerical study was conducted on the geomechanical behaviour of Oil Sands during penetration tests in which a steel wedge with an apex angle of either 20 degrees or 30 degrees was forced into compacted Oil Sands. The boundary conditions simulated in the laboratory tests are similar to shovel penetration into Oil Sands. The objective of the laboratory tests was to measure the force required to push a steel wedge into compacted Oil Sands. A wedge penetration test differs from conventional triaxial tests in that much more shear is generated. The laboratory data was needed to improve calibration of micro-mechanical input parameters for a two-dimensional discrete element model of Oil Sands constructed with Particle Flow Code (PFC). Initial model calibration was performed with triaxial test data and then a PFC model of the wedge penetration test was constructed. The measured force-displacement behaviour of the steel wedge was compared with PFC modelling results. It was found that different combinations of PFC particle and bond parameters could equally well replicate the laboratory triaxial compression data for bitumen-rich Oil Sands. When the wedge model was run, it was found that the resulting force required to penetrate the wedge into the Oil Sands was about four to six times higher than that measured. This clearly indicates that further research is required to improve the predictive capability of PFC models of Oil Sands.
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Hydraulic underground mining of Oil Sands : The next big step?
Cim Bulletin, 2020Co-Authors: Dwayne D. Tannant, C.d. Martin, B. RegensburgAbstract:This paper presents a mining concept for Oil Sands called hydraulic underground mining of Oil Sands or HUMOS. While this mining method is still at the conceptual stage, it has promise to allow extraction of bitumen from areas that are currently uneconomical or technically infeasible using surface mining or steam injection technologies. HUMOS is founded on a combination of recently proven technologies such as directional drilling, water-jet cutting of Oil Sands, slurry transportation, cold water extraction of bitumen, and thickened tailings. One key component in the mining concept is the caving of Oil Sands and the creation of an underground cavern. Scaled-down physical models need to be designed and built to demonstrate water-jet cutting, cave development, and in situ primary bitumen separation. These can be used as a proof of concept .
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Effect of Solid Wettability on Processability of Oil Sands Ores
Energy & Fuels, 2009Co-Authors: Trong Dang-vu, Dwayne D. Tannant, Shiau-yin Wu, Jacob H. Masliyah, Zhenghe XuAbstract:The wettability of mineral solids and bitumen isolated from nine different Athabasca Oil Sands ores was determined to establish its role in water-based extraction of bitumen from Oil Sands. The processability of Oil Sands ores was determined using Denver flotation tests. The contact angle of a water drop on a bitumen-coated silica wafer was measured using the sessile drop method. For fine solids (
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Wettability determination of solids isolated from Oil Sands
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2009Co-Authors: Trong Dang-vu, Dwayne D. Tannant, Shiau-yin Wu, Jacob H. Masliyah, Zhenghe XuAbstract:Abstract The purpose of this study is to determine the wettability of solids isolated from Oil Sands. The fine (−45 μm) and coarse (+106 μm −250 μm) fractions of the mineral solids were extracted from different Athabasca Oil Sands ores using water-based extraction in a Denver flotation cell. Four different methods were used to characterize the wettability of solids, i.e., contact angle, critical surface tension, hydrophilic/hydrophobic partitioning, and water drop penetration time (WDPT). Advantages and limitations of these methods were discussed. WDPT measurements were found to be the most sensitive for determining wettability of the solids extracted from Oil Sands. The effect of the protocol for isolating the solids from Oil Sands on solids surface properties was investigated. Solvent washing and solids drying were found to affect the wettability of the solids. Solids wettability measurements were corroborated with surface composition of the solids as determined by X-ray photoelectron spectroscopy.
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PFC Model of Wedge Penetration into Oil Sands
Discrete Element Methods, 2002Co-Authors: Dwayne D. Tannant, Caigen WangAbstract:An experimental and numerical study was conducted on the geomechanical behavior of Oil Sands during penetration tests in which a steel wedge was forced into compacted Oil Sands. The boundary conditions simulated in the laboratory test are similar to many common excavation activities that occur during Oil sand mining (e.g., shovel penetration into Oil Sands). The laboratory data was needed to improve calibration of input parameters for a two-dimensional numerical model of Oil Sands constructed with Particle Flow Code (PFC). The objective of the laboratory tests was to measure the force required to push a steel wedge into compacted Oil sand. A wedge penetration test differs from conventional triaxial tests in that much more shear is generated. The measured force-displacement behavior of the steel wedge was then compared with PFC modeling results.
Andrea J. Farwell - One of the best experts on this subject based on the ideXlab platform.
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Ecotoxicology of Oil Sands Aquatic Environments
2020Co-Authors: Andrea J. Farwell, D. George DixonAbstract:The Oil Sands industry in northern Alberta produces crude Oil by extracting bitumen from Oil Sands. Large volumes of process-affected material (tailings/waste water) are produced, containing polycyclic aromatic compounds (PACs), naphthenic acids (NAs) and salinity derived from the Oil Sands ore and its processing. Oil Sands aquatic reclamation is a challenge as Oil Sands process-affected material may have strong impacts on aquatic organisms. In this overview, we will address issues of water and sediment quality relevant to the development of Oil Sands aquatic reclamation strategies that produce healthy and sustainable aquatic ecosystems. Toxicological studies of whole process-affected water and tailings, extracts of Oil Sands derived NAs and PACs and modifying factors influencing toxicity to fish and other aquatic organisms will be highlighted. Algal and microbial production, and aquatic food web dynamics are processes that have received attention to date (e.g., in C and N stable isotope studies), in the belief that sustainable reclamation strategies will require an understanding of how these ecosystem processes are influenced by mining-related materials. This research will contribute to devising aquatic reclamation strategies, as well as providing baseline data for environmental monitoring and the much needed cumulative impact assessments for the Athabasca River drainage basin.
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Assessing the bioremediation potential of algal species indigenous to Oil Sands process-affected waters on mixtures of Oil Sands acid extractable organics
Ecotoxicology and Environmental Safety, 2016Co-Authors: Sarah E. Ruffell, Adam P. Woodworth, Anthony E. Bauer, Andrea J. Farwell, Lorna E. Deeth, Leslie M Bragg, Kirsten M. Müller, Richard A Frank, D. George Dixon, Mark R ServosAbstract:Surface mining extraction of bitumen from Oil sand in Alberta, Canada results in the accumulation of Oil Sands process-affected water (OSPW). In attempts to maximize water recycling, and because its constituents are recognized as being toxic, OSPW is retained in settling basins. Consequently, research efforts are currently focused on developing remediation strategies capable of detoxifying OSPW to allow for eventual release. One potential bioremediation strategy proposes to utilize phytoplankton native to the Alberta Oil sand region to sequester, break down, or modify the complex Oil Sands acid extractable organic (AEO) mixtures in OSPW. Preliminary attempts to quantify changes in total Oil Sands AEO concentration in test solutions by ESI-MS following a 14-day algal remediation period revealed the presence of unknown organic acids in control samples, likely released by the phytoplankton strains and often of the same atomic mass range as the Oil Sands AEO under investigation. To address the presence of these “biogenic” organic acids in test samples, ESI-MS in MRM mode was utilized to identify Oil Sands AEO “marker ions” that were a) present within the tested Oil Sands AEO extract and b) unique to the Oil Sands AEO extract only (e.g. atomic masses different from biogenic organic acids). Using this approach, one of the 21 tested algal strains, Stichococcus sp. 1, proved capable of significantly reducing the AEO marker ion concentration at test concentrations of 10, 30, and 100 mg L−1. This result, along with the accelerated growth rate and recalcitrance of this algal strain with exposure to Oil Sands AEO, suggests the strong potential for the use of the isolated Stichococcus sp. 1 as a candidate for bioremediation strategies.
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Food web structure in Oil Sands reclaimed wetlands
Ecological Applications, 2013Co-Authors: K. E. Kovalenko, A. L. Foote, K. R. Frederick, J. M.gardner Costa, Andrea J. Farwell, D. G. Dixon, C. Daly, K. Kennedy, Jan J C Ciborowski, Karsten LiberAbstract:Boreal wetlands play an important role in global carbon balance. However, their ecosystem function is threatened by direct anthropogenic disturbance and climate change. Oil Sands surface mining in the boreal regions of Western Canada denudes tracts of land of organic materials, leaves large areas in need of reclamation, and generates considerable quantities of extraction process-affected materials. Knowledge and validation of reclamation techniques that lead to self-sustaining wetlands has lagged behind development of protocols for reclaiming terrestrial systems. It is important to know whether wetlands reclaimed with Oil Sands process materials can be restored to levels equivalent to their original ecosystem function. We approached this question by assessing carbon flows and food web structure in naturally formed and Oil Sands-affected wetlands constructed in 1970-2004 in the postmining landscape. We evaluated whether a prescribed reclamation strategy, involving organic matter amendment, accelerated reclaimed wetland development, leading to wetlands that were more similar to their natural marsh counterparts than wetlands that were not supplemented with organic matter. We measured compartment standing stocks for bacterioplankton, microbial biofilm, macrophytes, detritus, and zoobenthos; concentrations of dissolved organic carbon and residual naphthenic acids; and microbial production, gas fluxes, and aquatic-terrestrial exports (i.e., aquatic insect emergence). The total biomass of several biotic compartments differed significantly between Oil Sands and reference wetlands. Submerged macrophyte biomass, macroinvertebrate trophic diversity, and predator biomass and richness were lower in Oil Sands-affected wetlands than in reference wetlands. There was insufficient evidence to conclude that wetland age and wetland amendment with peat-mineral mix mitigate effects of Oil Sands waste materials on the fully aquatic biota. Although high variability was observed within most compartments, our data show that 20-year-old wetlands containing Oil Sands material have not yet reached the same level of function as their reference counterparts.
K. E. Kovalenko - One of the best experts on this subject based on the ideXlab platform.
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Food web structure in Oil Sands reclaimed wetlands
Ecological Applications, 2013Co-Authors: K. E. Kovalenko, A. L. Foote, K. R. Frederick, J. M.gardner Costa, Andrea J. Farwell, D. G. Dixon, C. Daly, K. Kennedy, Jan J C Ciborowski, Karsten LiberAbstract:Boreal wetlands play an important role in global carbon balance. However, their ecosystem function is threatened by direct anthropogenic disturbance and climate change. Oil Sands surface mining in the boreal regions of Western Canada denudes tracts of land of organic materials, leaves large areas in need of reclamation, and generates considerable quantities of extraction process-affected materials. Knowledge and validation of reclamation techniques that lead to self-sustaining wetlands has lagged behind development of protocols for reclaiming terrestrial systems. It is important to know whether wetlands reclaimed with Oil Sands process materials can be restored to levels equivalent to their original ecosystem function. We approached this question by assessing carbon flows and food web structure in naturally formed and Oil Sands-affected wetlands constructed in 1970-2004 in the postmining landscape. We evaluated whether a prescribed reclamation strategy, involving organic matter amendment, accelerated reclaimed wetland development, leading to wetlands that were more similar to their natural marsh counterparts than wetlands that were not supplemented with organic matter. We measured compartment standing stocks for bacterioplankton, microbial biofilm, macrophytes, detritus, and zoobenthos; concentrations of dissolved organic carbon and residual naphthenic acids; and microbial production, gas fluxes, and aquatic-terrestrial exports (i.e., aquatic insect emergence). The total biomass of several biotic compartments differed significantly between Oil Sands and reference wetlands. Submerged macrophyte biomass, macroinvertebrate trophic diversity, and predator biomass and richness were lower in Oil Sands-affected wetlands than in reference wetlands. There was insufficient evidence to conclude that wetland age and wetland amendment with peat-mineral mix mitigate effects of Oil Sands waste materials on the fully aquatic biota. Although high variability was observed within most compartments, our data show that 20-year-old wetlands containing Oil Sands material have not yet reached the same level of function as their reference counterparts.
Zhenghe Xu - One of the best experts on this subject based on the ideXlab platform.
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Role of Dissolving Carbon Dioxide in Densification of Oil Sands Tailings
Energy & Fuels, 2011Co-Authors: Zhenghe Xu, Jacob H. Masliyah, Aman KhanAbstract:Carbon dioxide (CO2) was shown as a promising alternative for Oil Sands tailings treatment with economical and environmental benefits. This study aims to understand the role of CO2 addition in densification of Oil Sands tailings. In this study, CO2 was pressurized into two industrial whole tailings provided by Syncrude Canada Ltd. and Canadian Natural Resource Ltd. The optimal initial settling rate, supernatant clarity and solids content of sediment were achieved at a CO2 partial pressure of about 100 kPa. The improvement on densification of Oil Sands tailings by CO2 was mainly attributed to pH reduction under various CO2 partial pressures. The zeta potential of fines became less negative with decreasing pH, enhancing coagulation of fine solids. On the other hand, CO2 bubbles formed by dissolved gas under supersaturation pressure led to a less clear supernatant by disturbing the formed sediments. Supersaturation with nitrogen was applied to the Oil Sands tailings to verify the influence of dissolved gas o...
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Polymer aids for settling and filtration of Oil Sands tailings
Canadian Journal of Chemical Engineering, 2010Co-Authors: Xiaoyan Tara Wang, Zhenghe Xu, Xianhua Feng, Jacob H. MasliyahAbstract:Commercial Magnafloc 1011 (Percol 727) polymer and in-house synthesised Al-PAM polymer were used to flocculate Oil Sands tailings that were derived from low and high fines Oil Sands ores. Fines are defined as mineral solids less than 44 µm. The performance of polymers was evaluated in terms of tailings settling, filtration rate, and final moisture content of tilter cakes. Both polymers were shown to effectively flocculate the derived Oil Sands tailings and hence to enhance tailings settling. Al-PAM performed very well as a filtration aid. The final moisture content of the filter cake obtained from tailings derived from the low fines ore was 6.6 ± 1.2 wt.% and that from the high fines ore was 16.9 ± 0.8 wt.%. This class of polymer can provide an alternative approach for Oil Sands tailings disposal that has the potential to eliminate tailings ponds. However, the commercial Magnafloc 1011 polymer was found ineffective as a filtration aid for the two tailings tested in this study.
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Effect of Solid Wettability on Processability of Oil Sands Ores
Energy & Fuels, 2009Co-Authors: Trong Dang-vu, Dwayne D. Tannant, Shiau-yin Wu, Jacob H. Masliyah, Zhenghe XuAbstract:The wettability of mineral solids and bitumen isolated from nine different Athabasca Oil Sands ores was determined to establish its role in water-based extraction of bitumen from Oil Sands. The processability of Oil Sands ores was determined using Denver flotation tests. The contact angle of a water drop on a bitumen-coated silica wafer was measured using the sessile drop method. For fine solids (
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Wettability determination of solids isolated from Oil Sands
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2009Co-Authors: Trong Dang-vu, Dwayne D. Tannant, Shiau-yin Wu, Jacob H. Masliyah, Zhenghe XuAbstract:Abstract The purpose of this study is to determine the wettability of solids isolated from Oil Sands. The fine (−45 μm) and coarse (+106 μm −250 μm) fractions of the mineral solids were extracted from different Athabasca Oil Sands ores using water-based extraction in a Denver flotation cell. Four different methods were used to characterize the wettability of solids, i.e., contact angle, critical surface tension, hydrophilic/hydrophobic partitioning, and water drop penetration time (WDPT). Advantages and limitations of these methods were discussed. WDPT measurements were found to be the most sensitive for determining wettability of the solids extracted from Oil Sands. The effect of the protocol for isolating the solids from Oil Sands on solids surface properties was investigated. Solvent washing and solids drying were found to affect the wettability of the solids. Solids wettability measurements were corroborated with surface composition of the solids as determined by X-ray photoelectron spectroscopy.
