PRISM :: Browsing by Author "Achari, Gopal"

Browsing by Author "Achari, Gopal"

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Open Access
A contribution to risk-based inspection and maintenance planning for deteriorating pipelines and pressure vessels
(2017) Haladuick, Shane; Dann, Markus R; Maes, Marc; Achari, Gopal; Egberts, Philip; Huang, Qindan
Engineering systems are subject to deterioration processes, such as corrosion and fatigue, which reduce the resistance to failure. If failure occurs, it can have large social, economic, and environmental consequences. To mitigate this risk, regular inspections and maintenance are performed. To minimize the overall cost of operating the system, it is important to optimize the inspection and maintenance plan. Lifecycle risk-based inspection and maintenance planning, which involves determining the expected total cost of operating a system over its lifecycle, is the most established method of determining the optimal inspection and maintenance plan. However, lifecycle risk-based inspection and maintenance planning for complex engineering systems with many components requires a detailed analysis that can be computationally demanding; therefore, simplifications and assumptions are commonly used in the literature. The objective of this dissertation is to expand the state of knowledge in risk-based inspection and maintenance planning for pipelines and pressure vessels, removing many common assumptions and simplifications. Some aspects of the research specifically target pipelines or pressure vessels, while others are generic to any engineering system. Specifically regarding pressure vessels, a simple methodology is presented to determine the optimal maintenance time for a pressure vessel with an unexpectedly severe defect. This methodology is then expanded to account for the dependent failure events in pressure vessels with multiple defects and failure modes. For pipelines, a risk-based maintenance methodology is developed to decide whether it is better to continuously repair defects in a pipeline or to replace entire pipeline sections. This methodology also examines the impact of an uncertain lifecycle on risk-based maintenance planning. For general engineering systems, the use of heuristic algorithms in improving the computational efficiency of solving risk-based inspection and maintenance optimization problems is examined. Finally, a methodology is developed to perform risk-based inspection planning for the next inspection type, without requiring a lifecycle analysis. This study aids system operators in determining the optimal inspection and maintenance plan. It also provides methodology to perform risk-based inspection and maintenance planning in a computationally efficient or simpler manner, to make the techniques more practically applicable.
Open Access
A Decision Support System for Risk Management of Contaminated Sites
(2011) Kluck, Cheryl Lee; Achari, Gopal
Open Access
A gas generation, migration and extraction model for landfills
(2012) Wang, Chien-Kai Kenneth; Achari, Gopal
A numerical model is developed to simulate the generation, movement, extraction, and surface emission of landfill gas as well as possible air intrusion in a sanitary landfill equipped with an active or a passive gas collection system. The model was validated using results and data published in literature and has been used to study how the efficiency of a gas collection system may be impacted by a number of factors including vacuum pressure, well screen length, intermediate and final covers' thickness and permeability, number of gas collection wells and direction of well placement. The results suggest that a higher gas collection rate can be achieved by using a vertically placed well with a stronger vacuum pressure, a longer well screen, and a thicker and less permeable final cover, while undesirable air intrusion may be minimized by installing a larger number of wells.
Open Access
Advanced Oxidative Processes for Treatment of Emerging Contaminants in Water
(2016) Mehrabani-Zeinabad, Mitra; Achari, Gopal; Langford, Cooper; Bergerson, Joule; Tay, Joo-Hwa Andrew; Ponnurangam, Sathish; Surampalli, Rao
In this research, degradation of emerging contaminants in municipal and industrial wastewater was studied by using a variety of advanced oxidation processes. Bisphenol A (BPA) and bisphenol S (BPS) were selected as candidate emerging contaminants in municipal wastewater and sulfolane as a candidate for industrial wastewater. Degradation kinetics of different oxidation processes in spiked water and contaminated wastewater/groundwater were investigated in batch as well as in a flow-through photo-reactor. Degradation of BPA and BPS in spiked water and post-secondary treated wastewater was studied using UVC, UVC/H2O2, O3 and UVA/O3 in a batch photo-reactor. The effective parameters of each process were identified and their impacts on degradation rates were further investigated. Based on the results obtained, the fate of BPA and BPS in municipal wastewater as they move through the UV disinfection unit of a local wastewater treatment plant in Calgary, Canada, was evaluated. It was found that only 1% of BPA and 6% of BPS were degraded in the disinfection unit. However, should 0.042 M H2O2 be added to the wastewater stream entering the disinfection unit, 56% of BPA and 47% of BPS can be degraded. By implementation of O3 and UVA/O3 processes, degradation levels could exceed 95%. Several oxidative methods were used to degrade sulfolane in spiked water and contaminated groundwater in a batch photo-reactor. These include UVA and UVC irradiation with suitable photoactive oxidants, including O3, H2O2, TiO2-based photocatalysis and their combinations. A synergistic effect was observed in the combination of H2O2 and O3 photolysis. The highest rate of sulfolane loss was attributed to UVC/O3/H2O2, UVC/H2O2 and UVC/O3 processes. Finally, the science established in the batch experiments for degradation of the candidate emerging contaminants in municipal and industrial wastewater was further developed into a technology for treating BPS and sulfolane in a flow-through photo-reactor with recirculation. It was found that the most effective process in terms of overall mineralization of BPS and sulfolane in post-secondary treated wastewater and contaminated groundwater, respectively, is the UVC/O3/H2O2 process. The effective parameters were identified and optimized for each of the emerging contaminants.
Open Access
Aerobic Granular Sludge for Treatment of Naphthenic Acids in Semi-Continuous and Batch Modes
(2019-01-03) Tiwari, Shubham Sudhindra; Tay, Joo Hwa; Zhou, Qi; Achari, Gopal
Wastewater from the Canadian mining oil sands industry is currently stored in tailings ponds, due to the difficulty in treatment of toxic recalcitrant compounds called naphthenic acids (NAs). The current project aimed at NA treatment using aerobic granular sludge (AGS) in two separate experiments. The first experiment was a proof-of-concept study aimed at assessing the shock response and treatability of commercial NAs over 21 days. It was conducted in three phases, i.e. introduction, starvation and monitoring. Each phase had chemical oxygen demand (COD) removal efficiencies of 54.8%, 23.9% and 96.1%, and NA removal efficiencies of 71.8%, 43.3% and 67.0%, respectively. Specific COD removal rates ranged between 2678 - 6864 g COD/m3/d, whereas specific NA removal rates ranged between 0.5-12.2 g NA/m3/d. These high rates were attributed to higher AGS biomass requiring higher COD consumption, and larger AGS surface area facilitating biodegradation and biosorption. The second experiment subjected mature AGS to three model NA concentrations (10, 50 and 100 mg/L), at three varying supplemental carbon source concentrations (600, 1200 and 2500 mg/L) in batch reactors. Cyclohexane carboxylic acid (CHCA), cyclohexane acetic acid (CHAA) and 1-adamantane carboxylic acid (ACA) were chosen to study structure-based degradation kinetics. The optimal COD was found to be 1200 mg/L. CHCA was removed completely with biodegradation rate constants increasing with lower NA concentrations and lower COD concentrations. CHAA was also removed completely, however, an optimal rate constant of 1.9 d-1 was achieved at NA and COD concentrations of 50 mg/L and 1200 mg/L, respectively. ACA removal trends did not follow statistically significant regressions; however, degradation and biosorption helped remove ACA up to 19.9%. Pseudomonas, Acinetobacter, Hyphomonas and Brevundimonas spp. increased over time, indicating increased AGS adaptability to NAs.
Open Access
An Evaluation of Different Risk Ranking Systems for Contaminated Sites
(2014-01-27) Sha, Huimei; Achari, Gopal; Langford, Cooper
Risk ranking systems for contaminated sites have been developed by different jurisdictions with similar purpose, but it is not clear whether they provide results that are comparable. The United States’ Preliminary Assessment (PA) system, Sweden’s Methods for Inventories of Contaminated Sites (MICS) and New Zealand’s Risk Screening System (RSS) methods are assessed in this thesis. These methods were compared with each other and with the Canada’s National Classification System for Contaminated Sites (NCSCS) as well as a preliminary quantitative risk assessment (PQRA) method. The objectives were to determine if all these systems can yield similar recommendations regarding further actions, and to assess if there are acceptable correlations between the different methods. The study concludes that the PA, MICS and NCSCS methods can achieve similar conclusions, although there is a certain degree of inconsistency that is present; the RSS system can distinguish the very high and very low risk sites and; acceptable correlations exists among the these methods except for between PA and PQRA.
Open Access
An Evaluation of the 2008 National Classification System for Contaminated Sites
(2010) Thiessen, Ronald James; Achari, Gopal
Open Access
An investigation of a photochemical approach for the remediation of PCB-contaminated soils
(2005) Dhol, Arvinder S.; Achari, Gopal
Open Access
An investigation on a photochemical remediation of polychlorinated biphenyls in transformer oil
(2012) Kong, Jiansong; Achari, Gopal; Langford, Cooper H.
The focus of this research is to develop photo based remediation methods for polychlorinated biphenyls (PCBs) in transformer oil (TO), and to investigate the extraction of PCBs from TO. If the PCBs are successfully extracted, the cleaned oil can be recycled and PCBs in the extractant can be photochemically degraded. The study on direct dechlorination of PCB138 in TO using 254nm ultraviolet (UV) light, indicated >99% dechlorination within 1 h. Photosensitized dechlorination of PCB 13 8 in TO using visible light in the presence of methylene blue (photosensitizer) and triethylamine (sacrificial electron donor), indicated 94% reduction within 30 min. The second part of this thesis deals with liquid-liquid extraction, used to separate PCBs from TO. Three extraction solvents were used: dimethyl sulfoxide (DMSO), sulfolane and acetonitrile. The results show that DMSO was the preferred solvent for extraction of PCBs from TO. After extraction, PCBs in DMSO could be complete dechlorinated within 3 min using visible light in presence of methylene blue (MB) as a photosensitizer, sodium borohydride as a reducing agent and under dearation condition. After dechlorination process, the cleaned DMSO can be recycled or reused.
Open Access
Analysis of Oil and Gas Projects-With Focus on SAGD Projects
(2016) Kumar, Jatinder; Jergeas, George; Sadeghpour, Farnaz; Al-Hussein, Mohamed; Achari, Gopal; Ruwanpura, Janaka; Balakrishnan, Jaydeep
Alberta projects have experienced cost growth, schedule growth and low productivity, necessitating a need to measure and compare project performance and productivity of oil and gas projects. There is limited research on the project performance of Steam Assisted Gravity Drainage (SAGD) projects. The primary purpose of this research was to quantitatively assess the project performance of oil and gas projects in Alberta with special focus on SAGD projects. The quantitative assessments included the project performance and productivity analysis for location of projects (Alberta and U.S. projects), different time periods (Phase 1: 2006-2009 vs. Phase 2: 2010-2014), and different types of projects (pipeline and SAGD projects), and examination of the relationship between project execution strategies and project performance. SAGD projects were analyzed separately, and industry experts were interviewed to understand industry perspective on cost and schedule performance, risks and lessons learned on SAGD projects. During the research, 73 oil and gas projects from Alberta were analyzed. Data were collected using the Construction Owners Association of Alberta (COAA)-PAS. Statistical tools were used to analyze project performance and to assess the impact of project execution strategies on project performance. Different trends have been observed between Phase 1: 2006-2009 and Phase 2: 2010-2014. The comparison of project performance and productivity directed industry to where efforts could be made for continuous improvement. Data from 18 SAGD projects were analyzed to develop characteristics of SAGD projects. The project performance, which includes growth factors, phase duration factors, phase cost factors, equipment ratios, and engineering and construction productivity metrics that could have practical applications for estimating and project performance benchmarking is listed in tabular form. Interviews from industry experts provided definition of capacity, 52 new metrics, and a list of major risks and lessons learned during the SAGD project execution. This research improved the industry understanding of challenges and risks faced on SAGD projects. This research also observed the trends and comparison of project performance, engineering and construction productivity, which identified the areas for continuous improvement. This also concludes that there is room for further improvement in project and productivity performance for oil and gas projects in Alberta.
Open Access
Application of the Waxman Smits model for estimating groundwater quality from in-situ measurements of electrical conductivity
(2003) Leszkowicz, John Kasimir; Achari, Gopal; Bentley, Laurence R.
Open Access
Atrazine: its occurrance and photochemical treatment in water
(2011) Lazorko-Connon, Suzanne; Achari, Gopal; Langford, Cooper H.
Open Access
Biological and Advanced Oxidation Processes for the Treatment of Sulfolane Contaminated Waters
(2020-01-07) Khan, Muhammad Faizan; Achari, Gopal; Black, Kerry E.; Kimura, Susana Y.; Gieg, Lisa Marie; Khan, Faisal Masood
Sulfolane contamination has increasingly become a major environmental concern around the world. This research builds on past research on sulfolane degradation using a variety of different advanced treatment technologies. Initially, the performance of an integrated technology combining biological activated sludge with advanced oxidation process (AOP) (UVC/H2O2) in sequence was evaluated in a batch reactor resulting in >81% sulfolane degradation in less than 24 h. Evaluation of the impact of biological process on AOP showed sulfolane concentration beyond 30 mg/L and presence of TSS >44 mg/L can negatively impact the UVC/H2O2 efficiency for sulfolane degradation. The application of UVC/H2O2 after biological treatment was an advantage as UVC/H2O2 could perform dual roles of oxidation and disinfection. As aerobic granulation is perceived to be more advanced than activated sludge process, two approaches of forming sulfolane degrading aerobic granules (SDAG) were investigated. The adaptation of pre-grown granules to sulfolane environment required a longer period to form SDAG compared to coaggregation of pre-grown granules with bacterial culture native to sulfolane contaminated site. Scanning electron microscopic images revealed dominant filamentous bacteria on the surface of granules. The stability and settleability of SDAG were also investigated under different environmental conditions. Subsequently, a novel integration of aerobic granulation with UV/H2O2 process in a continuous flow-through operation sequence showed elimination of more than 99.99% of sulfolane in less than 6.3 h of combined retention time. The degradation kinetics of sulfolane were also evaluated and the flow-through system showed generation and maintenance of a healthy aerobic granular system. Additionally, various key factors were also identified that govern residual H2O2 concentration in UV/H2O2 effluents. Finally, a pilot-scale field investigation was conducted using a pressurized ozone treatment system to degrade sulfolane in contaminated groundwaters. A series of batch and continuous flow systems were studied to determine the degradation kinetics and evaluate augmentation of oxidation process with the addition of secondary chemicals with ozone. Groundwater matrix played a crucial role in the efficacy of ozone treatment and intermittently sparged ozone injection was evaluated as a viable option for ozone field applications. Nevertheless, bromate concentrations higher than drinking water guidelines were detected in treated groundwater after ozone treatment and this will need further research.
Open Access
Biological nutrients eradication employing Aerobic Granulation
(2018-07-13) Not available, Anrish; Tay, Joo Hwa (Andrew); Chu, Angus; Achari, Gopal
Nutrients (nitrogen and phosphorus), since mid-20th century, have been a rising matter of concern- impacting the quality of natural water bodies and stressing the wastewater treatment facilities. The increased availability of nitrogen and phosphorus are known to cause the excessive aging of lakes, eutrophication, thus depriving these bodies of oxygen, leading to various ecological, human health and socio-economic impacts. The phosphorus discharged from untreated or under treated municipal wastewater considerably adds to eutrophication. Although the conventional processes for wastewater treatment are able to remove the organics yet contains residual nutrients in the effluent. These residual amounts exceed the desired effluent limitations, which are getting stringent. The following research provides an insight of an emerging biotechnology: Aerobic Granulation, for its suitability to remove phosphorus (growth limiting nutrient) and nitrogen existing in domestic wastewater. The research focuses on investigation of different mechanisms supporting domestic level phosphorus removal in aerobic granular system. Granulation is a novel biotechnology based on self-immobilization of diverse microbes into a packed and dense structure giving it a unique ability to retain higher biomass, exceptional settleability, and resistance to toxicity and fluctuating organic loadings. In comparison to the conventional treatment processes, granulation technology also offers smaller footprint and low operational cost. A characteristic property of the granules is that these can be tailored as per the treatment requirements. The stratified structure of the granules due to mass transfer diffusion provides favorable conditions for phosphorus removal. The co-existence of aerobic zone and anaerobic zone in the granules, as documented in the literature, supports the simultaneous removal of nitrogen and phosphorus. The lab-scale bioreactor was setup in Hydraulics lab at University of Calgary from February 2016- August 2016. Synthetic wastewater was used for the experiments with variation in COD and phosphorus concentration in the reactor for evaluating the significance of the operational factors. The major phenomenon responsible for phosphorus removal at low C:P was biological assimilation. At a high C:P ratio, biological accumulation and biologically induced phosphorus precipitation were identified as the phosphorus removal phenomena. Microbiological analysis through Polymerase chain reaction of extracted 16r RNA genes indicated the presence of Rhodocyclaceae; phosphorus removing bacteria with a low temperature based biological phosphorus removal rate. Data analysis illustrated a significance of C:P on aerobic granular phosphorus removal process. The results reflect the suitability of aerobic granulation for municipal level phosphorus removal provided optimum operational conditions are maintained. A scale up version of this technology could be used for deeper insight into real domestic wastewater for advanced wastewater treatment processes.
Open Access
Characterization and Removal of High Concentration Silica in Steam-Assisted Gravity Drainage (SAGD) Evaporator Blowdown Wastewater
(2024-05-21) Rao, Saheli; Mehrotra, Anil Kumar; Achari, Gopal; Ponnurangam, Sathish; Lu, Qingye
Evaporator blowdown (EBD) wastewater is a highly alkaline stream generated from the evaporation-based treatment of produced water arising from steam-assisted gravity drainage operations. It contains elevated concentrations of dissolved solids, of which silica poses a major challenge in both the waste stream treatment and its disposal. Silica has a propensity for scaling and fouling the process equipment. Additionally, pH-neutralization of highly concentrated silica brines results in silica gelation. This makes it difficult to filter and dewater before its disposal via down-hole injection. Moreover, the interaction of silica and other chemicals present in the EBD with those in underground formation waters can result in the plugging of the injection wells due to mineral precipitation. In this research, the removal of silica from these concentrated waste streams (largely comprised of brine solution) is investigated, while also understanding the speciation of silica to mitigate challenges during deep well injections. A systematic experimental program was conducted to investigate the effects of SiO2 concentration, NaCl:SiO2 ratio, and pH on the residual silica concentration, percent silica removal, filtration rate, and filtration effectiveness. The objective was to prevent silica gelation. The results indicated that when the NaCl:SiO2 ratios were higher than 4.5, silica precipitation during pH reduction did not lead to the formation of gel or sol. Additionally, the optimal ranges of factors for achieving the maximum silica removal, the highest filtration rate, the best filtration effectiveness, and the minimum residual silica concentration were determined using 3D response surfaces. Further, an investigation into the characterization and treatment of evaporator blowdown was conducted. The impact of acid treatment to remove silica and organics by filtration was studied. Both HCl and H2SO4 gave similar silica and organic removal efficiencies. The HCl-treatment was investigated further with both the EBD and lab-prepared silica solutions for silica removal efficiency and filtration performance. The experiments conducted at ~20°C demonstrated higher silica removal efficiencies at pH of 10 and 8, whereas higher organic removal efficiencies were obtained at pH of 4 and 2. The experiments conducted at an elevated temperature (~80°C) showed enhanced silica removal at a pH of 8 and higher organic removal at a pH of 2. The precipitated solids were characterized using XRD and ATR-FTIR spectroscopy to identify the minerals and functional groups. The XRD patterns demonstrated that the solids generated were amorphous. This research was undertaken to investigate the speciation and saturation indexes of minerals under various process conditions using equilibrium geochemical modelling in EBD wastewater and mixed waters resulting from combining EBD and formation waters. Parameters such as pH, acid type, and temperature were assessed for their impact on the speciation of silica and other species, as well as mineral saturation indices in EBD. Results highlighted the significant influence of pH on the speciation of silica and other species. The addition of either HCl or H2SO4 had no significant effect on the saturation indexes of silicate minerals, or the concentrations of silica and carbonate species. Additionally, simulations were performed for the mixture of untreated EBD and treated EBD at alkaline, neutral, and acidic pH levels with two formation waters. The major species in these mixed waters were silicates, sulphates, and carbonates. Simulations conducted on these mixed waters suggested that disposing of neutral to slightly acidic evaporator blowdown, as opposed to the alkaline EBD, in deep wells is conducive to preventing plugging and clogging issues that may result from mineral precipitation.
Open Access
Characterization and Treatment of Oil Sands Blowdown Water
(2016) Martez, Vitselle; Achari, Gopal; Langford, Cooper; Nowicki, Edwin; Priest, Jeffrey; Gay De Montella, Rafael; Singhal, Ashok
The high concentrations of organic and inorganic impurities from the blowdown water of the Steam Assisted Gravity Drainage (SAGD) process in the oilsands operations cause significant operational and environmental issues. In this study the actual SAGD boiler and evaporator blowdown was investigated and found to contain complex mixtures of TSS, TOC and TDS. Further investigations were focused on SAGD boiler blowdown (BBD) water and included the screening of seven advanced oxidation processes (AOPs) which resulted in the selection of three O3/UV, H2O2/UV and O3/H2O2/UV AOP’s for testing TOC degradation in each sequence of the HCl-acidified, CaO-alkalized, CO2-neutralized and original BBD waters. O3/H2O2/UV irradiation showed effective degradation in the neutralized, alkalized, acidified and original BBD at 70%, 68.3%, 55.6% and 9.4% TOC removal. An unique, semi-batch treatment system was designed, integrated and evaluated using HCl-acidified, CaO-alkalized, CO2-neutralized BBD water in three stages; (1) Stage A; precipitation and centrifugation for TSS and TOC removal, (2) Stage B; O3/H2O2/UV for TOC degradation, and (3) Stage C; reverse osmosis filtration for the TDS and residual TOC removal. Stage A results showed that the HCl-acidified BBD at pH 4.2 achieved the highest TOC removal by 44.7% and TSS by 98.5% likely because the net reduction in the molecular electrical repulsion and neutralization of acid groups led to their aggregation and removal. Stage B results showed that the O3/H2O2/UV achieved the highest TOC removal of 68.0% in the CO2-neutralized BBD likely because interferences of the competing inorganic carbonate and bicarbonate species that scavenge hydroxyl radicals were minimized. Stage C results showed that reverse osmosis filtration purified all samples, but achieved the highest removal of 99.7% residual TOC and 98.8% TDS in the HCl-acidified BBD and the highest permeate recovery at 40.5% in the alkalized and neutralized BBD. Since there is a lack of published information on SAGD blowdown the result of this study is significant and a precursor to advancing future research solutions.
Open Access
Co-digestion of agricultural, municipal and agro-industrial wastes in rural communities
(2007) McDonald, Tanya; Achari, Gopal; Abiola, Abimbola
n rural communities, such as Olds, Alberta, energy may be produced though anaerobic codigestion of municipal, agricultural and agro-industrial wastes. An inventory within a 40km radius of Olds revealed that almost 600,000 tonnes of waste are generated annually (98.4% manure) with an electrical potential of 83 GWh. Analysis of beef, hog, dairy and poultry manure, offal, food, grass and biosolids identified the potential for waste blending to optimize solids content and nutrient balance. In laborat01y tests, biogas yield increased from 0.382 m3/kg volatile solid (VS) with beef manure to 0.513 m3/kg VS with co-digestion of 30% hog manure, and 0.500 m3/kg VS with 30% offal. In pilot tests, methane content was increased from 58% to 63% through co-digestion of beef manure with beef manure. The increased yield observed in the laboratory tests was not confirmed due to process inhibition and the limited capability for process control in the pilot digesters.
Open Access
Co-Fermentation Strategy for Augmented Carbon Source Availability in Biological Nutrient Removal Systems: Optimization and Performance Evaluation
(2024-09-18) Hosseini Yazdi, Seyed Mohammad Sadegh; Chu, Angus; Achari, Gopal; Black, Kerry; Ponnurangam, Sathish; Hamza, Rania
This research delves into an innovative approach within the field of wastewater treatment, focusing on the co-fermentation of Primary Sludge (PS) with Fermented Sludge (FS), Soft Drink Wastewater (SDWW), and Yeast Wastewater (YWW) to produce volatile fatty acids (VFA). The utilization of waste materials in wastewater treatment, particularly for the synthesis of VFA, represents a significant stride towards sustainable and eco-friendly practices. VFA is crucial intermediates in the biological nutrient removal (BNR) process and play a key role in the anaerobic digestion and biosynthesis of bioplastics and biofuels. The study employs batch fermentation experiments using PS obtained from wastewater treatment facilities, a critical step in the advanced treatment of wastewater. The aim was to investigate the impact of co-substrate addition and different feeding mode on VFA production and composition. Key VFA identified include acetic acid, propionic acid, iso-butyric acid, butyric acid, isovaleric acid, and valeric acid, with acetic acid and iso-butyric acid predominantly yielding the highest. Further, the research explores the optimization of Food-to-Microorganism ratios, temperatures, and mixing conditions. This is in line with the latest advancements in wastewater treatment which emphasize process optimization for enhanced efficiency and sustainability. The findings reveal substantial enhancements in VFA/SCOD ratios under specific operational conditions, indicating a promising avenue for improved biogas production. Microbial community analysis in the study provides deeper insights into the biological aspects of wastewater treatment. Dominant phyla like Bacteroidota, Campilobacterota, Firmicutes, Fusobacteriota, and Proteobacteria were identified, which are instrumental in the biodegradation and nutrient cycling processes in wastewater systems. The study's outcomes hold significant implications for the advancement of wastewater treatment technologies. The addition of biodegradable SDWW and YWW not only improves the fermentation profile but also substantially enhances VFA yields, showcasing the potential of co-fermentation in wastewater treatment. These findings underline the importance of integrating innovative biological processes for effective wastewater management, ultimately contributing to the development of more sustainable, efficient, and eco-friendly treatment strategies.
Open Access
Co-Injection of Non-Condensable Gas and Foam in SAGD using a Modified Well Configuration
(2023-12-19) Zhang, Yushuo; Maini, Brij B.; Chen, Zhangxing; Sarma, Hemanta Kumar; Achari, Gopal; Rao, Dandina Nagaraja
The purpose of this project is to evaluate the performance of a non-condensable gas (NCG) foam as an additive to the steam assisted gravity drainage (SAGD) process using the conventional as well as modified well configurations. Both laboratory experiments and numerical simulations were used in the study. For safety reasons, nitrogen gas was used in the laboratory experiments to form the foam. However, in numerical simulations, methane is used as the gas component of the foam. The purpose of foam in this process is to reduce the heat loss and to decrease the residual oil saturation. Modified well configurations are designed to enhance steam efficiencies in the target zones. SAGD experiments were conducted in linear sand-packs to evaluate the effects of NCG and Foamed NCG as steam additives on the oil recovery performance. The value of residual oil saturations under NCG or foamed NCG conditions were determined through history matching of these experiments with numerical simulation. Several different foaming agents were evaluated for their effectiveness in reducing the residual oil saturation and achieving high recovery factor. The best performing foaming agent NC160 was then evaluated in a linear physical model for its foam flow characteristics. The results of these tests were also history-matched with a thermal reservoir simulator to determine the foam flow characteristics that can be applied to field scale simulations. A numerical simulation study of Long Lake Pad 16 found that steam only SAGD operation in 10 years had a cumulative Steam Oil Ratio (cSOR) of 6.23 and the total oil production of 79,193 m3. However, the best performing case of foam assisted SAGD, using three horizontal wells configuration, reduced the cSOR to 3.94 and increased the total oil production to 85,068 m3. As expected, a foam insulation layer formed above steam chamber, which resulted in superior performance regarding steam efficiency. This field scale simulation study was based on the foam flow parameters determined through history matching of the lab-scale physical model tests.
Open Access
The Community-Led Approach: A Holistic Methodology to Addressing Rural Drinking Water Advisories in Samson Cree Nation
(2023-03-15) Lauret, Ayla; Black, Kerry; Sleep, Sylvia; Achari, Gopal
Drinking Water Advisories (DWAs) affect Indigenous Communities across Canada, with focus being given to specific problems impacting centralized systems. This thesis explores the largely undocumented rural systems context and how wastewater systems must be considered in tandem. In partnership with Samson Cree Nation, through Indigenous Research Methodologies like Two-Eyed Seeing this thesis presents research that investigated the community’s approach to solving drinking water concerns. Using deductive thematic analysis, the qualitative data was used to evaluate the benefits and challenges of a community-led approach and to quantify the impact that DWAs have on Samson Cree Nation residents. Historical data and onsite inspection data was evaluated to define the extent of DWA’s, the condition of rural servicing infrastructure, and the impact of existing regulation and water governance practices. Findings indicated that the community-led approach allowed the Nation to advocate and articulate issues specific to the Nation and develop solutions that reflected the community’s unique needs. Quantitative data showed that 15% of homes were under a Boil Water Advisory and up to 50% of homes under Do Not Consume orders. A majority of rural water and septic systems were beyond their expected life and 70% of septic systems had failed and been converted to a ‘shoot-out’ septic waste system, within close proximity to a house and/or well. Considering the prevalence of DWAs, the issue extends beyond merely physical condition. The existing regulations and funding policies are outdated and counter to long-term solutions. Within Samson Cree Nation, the lack of clear regulation and quality control has created uncertainties and inconsistencies. Specifically, in the lack of monitoring and regulation surrounding construction. Minimal operation and maintenance have resulted in failing infrastructure and general distrust across the Nation both in individual systems and the Nations capacity to address concerns. Other issues identified by interviewees included the Nations’ lack of capacity and awareness about rural water issues. Overall, the success of the Nation-led approach highlights the importance of Indigenous-led partnership and collaboration. However, to obtain long-term solutions for DWAs, the regulations and policies that govern must be adapted to minimize the prevalence of short-term band-aid solutions.