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Pierre R Berube - One of the best experts on this subject based on the ideXlab platform.
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air Sparging for fouling control
2020Co-Authors: Pierre R BerubeAbstract:Abstract Knowledge and practice of air Sparging for fouling control has evolved over the past 30 years, and is expected to continue to do so in the years to come. This evolution has enabled a substantial improvement in air-Sparging efficiency and a corresponding reduction in the overall operating costs of membrane bioreactors (MBRs) to levels comparable to those for conventional activated sludge systems (CASs). This chapter provides a synopsis of the current state of knowledge on the use of air Sparging for fouling control in MBRs and provides insight into potential further improvements that can be realized.
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optimization of air Sparging and in line coagulation for ultrafiltration fouling control
Separation and Purification Technology, 2017Co-Authors: Heather E Wray, Pierre R Berube, Robert C AndrewsAbstract:Abstract A major drawback to ultrafiltration membrane operation for drinking water treatment is fouling, which results in lower water production and increased maintenance costs. The impact of different fouling mitigation strategies including, Sparging conditions (duration and air flow rate) as well as phased in-line coagulation were investigated at pilot-scale. Unexpectedly, Sparging during permeation and backwash resulted in a significantly higher rate of increase in irreversible resistance compared to Sparging only during backwash. Lower irreversible fouling observed without Sparging during permeation was attributed to the formation of a protective layer on the membrane in the absence of Sparging. Sparging at reduced air flow rates and intermittently, during the permeation cycle did not improve the irreversible resistance rate when compared to Sparging only during backwash. The application of phased in-line coagulation to pre-coat membranes was also investigated. Coagulating for only the first half of the permeation cycle (phased coagulation) did not negatively impact membrane performance in terms of irreversible resistance and organics removal. Phased coagulation, which would lead to reduced coagulant and sludge disposal costs, appears to be a promising fouling control strategy.
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distribution of surface shear stress for a densely packed submerged hollow fiber membrane system
Desalination, 2015Co-Authors: Syed Z Abdullah, Pierre R Berube, Heather E Wray, Robert C AndrewsAbstract:Abstract Surface shear stress induced by different air Sparging regimes on a submerged hollow fiber ultrafiltration module with horizontally-oriented, densely packed fibers was characterized. Continuous and intermittent (cycling on and off) coarse bubbles (0.75–2.5 mL), as well as large pulse bubble (150 and 500 mL) Sparging were considered for a range of air flow rates. The power required to induce surface shear stress on the surface of the hollow fibers was substantially lower when using large pulse bubble Sparging compared to both continuous and intermittent coarse bubble Sparging. Results indicated that the air flow required for pulse bubble Sparging was more than 80% lower than that required for coarse bubble Sparging to induce comparable surface shear stress (and corresponding fouling control). This study demonstrates the potential value and efficiency of pulse bubble air Sparging as a fouling control option in densely packed hollow fiber membrane systems.
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pulse bubble Sparging for fouling control
Separation and Purification Technology, 2014Co-Authors: Sepideh Jankhah, Pierre R BerubeAbstract:Abstract The extent of fouling control in air sparged submerged membrane systems is dependent on the hydrodynamic conditions generated by Sparging and the resulting shear stress induced onto membranes. Although the optimal Sparging conditions (i.e. bubble size and frequency) that promote fouling control remain unclear, recent studies suggest that pulse bubble Sparging is more efficient for fouling control than coarse bubble Sparging. The present study demonstrated that pulse bubble Sparging was substantially more effective at transferring power to the membranes than coarse bubble Sparging. Pulse bubble Sparging required approximately 50% less power for fouling control than coarse bubble Sparging. The spatial distribution of fouling was not homogenous in the system; lower fouling rates were observed in the zone of influence of bubbles. The width of the zone of influence induced by gas Sparging increased with bubble size and frequency, indicating that the size and frequency of bubbles can be optimized to minimize the required number of spargers in a system and therefore the total volume of gas required for fouling control.
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ultrafiltration fouling impact of backwash frequency and air Sparging
Separation Science and Technology, 2014Co-Authors: Lan Li, Robert C Andrews, Heather E Wray, Pierre R BerubeAbstract:A bench-scale study was performed to optimize backwash frequency and air Sparging conditions during ultrafiltration (UF) for drinking water treatment in order to minimize hydraulically irreversible fouling as well as operating and maintenance costs. Surface shear stress representing different air Sparging conditions (continuous coarse bubble, intermittent coarse bubble, and large pulse bubble) was applied in combination with various backwash frequencies (0.5, 2, and 6 hours) during UF of two natural surface waters. Results indicated that air Sparging during permeation with intermittent coarse or large pulse bubbles significantly reduced the rate of irreversible fouling. This allowed for longer permeation times (up to 6 hours) between backwashing, when compared to a baseline condition which assumed a 0.5 h-backwash frequency with no air Sparging during permeation. As a result, operation and maintenance cost savings estimated at > $350,000/year for a 29 MLD membrane train could be realized. This study demon...
Michael D Annable - One of the best experts on this subject based on the ideXlab platform.
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surfactant enhanced air Sparging with viscosity control for heterogeneous aquifers
Hydrogeology Journal, 2019Co-Authors: Hobin Kwon, Jaekyeong Choi, Michael D AnnableAbstract:The effects of surface-tension and/or viscosity changes in groundwater on the remedial performance of air Sparging for heterogeneous aquifers were investigated. The study used a one-dimensional (1-D) column and a two-dimensional (2-D) flow-chamber aquifer model. To introduce a heterogeneous setting, the middle part of the model was packed with a finer soil [LKZ, low hydraulic conductivity (K) zone]. Fluorescein sodium salt was used at 200 mg/L for all experiments as a surrogate contaminant. For the 1-D column experiments, the rate of fluorescence decay in the LKZ during surfactant-enhanced air Sparging (SEAS) was significantly higher than during the standard air sparing (AS) process without additives; the area of fluorescence loss, measured after 17 h of air Sparging (including ozone), was double and triple that of the conventional AS process, for SEAS without thickener (SEAS1) and SEAS with thickener (SEAS2), respectively. Experimental results using the 2-D chamber also confirmed the enhanced air intrusion into the LKZ during the SEAS process. The air fluxes through the LKZ increased by 47 and 103% for the SEAS1 and SEAS2 compared to AS, respectively; and 79 and 90% of fluorescence disappeared in the LKZ during ozone injection for SEAS1 and SEAS2, respectively, whereas only 10% disappeared for AS during the 3-h experimental period. The findings of this study indicate that the AS process, at low surface tension and increased groundwater viscosity may be a viable alternative to the conventional AS process for aquifers of heterogeneous hydrogeological formations.
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effect of increased groundwater viscosity on the remedial performance of surfactant enhanced air Sparging
Journal of Contaminant Hydrology, 2018Co-Authors: Jaekyeong Choi, Hobin Kwon, Michael D AnnableAbstract:Abstract The effect of groundwater viscosity control on the performance of surfactant-enhanced air Sparging (SEAS) was investigated using 1- and 2-dimensional (1-D and 2-D) bench-scale physical models. The viscosity of groundwater was controlled by a thickener, sodium carboxymethylcellulose (SCMC), while an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), was used to control the surface tension of groundwater. When resident DI water was displaced with a SCMC solution (500 mg/L), a SDBS solution (200 mg/L), and a solution with both SCMC (500 mg/L) and SDBS (200 mg/L), the air saturation for sand-packed columns achieved by air Sparging increased by 9.5%, 128%, and 154%, respectively, (compared to that of the DI water-saturated column). When the resident water contained SCMC, the minimum air pressure necessary for air Sparging processes increased, which is considered to be responsible for the increased air saturation. The extent of the Sparging influence zone achieved during the air Sparging process using the 2-D model was also affected by viscosity control. Larger Sparging influence zones (de-saturated zone due to air injection) were observed for the air Sparging processes using the 2-D model initially saturated with high-viscosity solutions, than those without a thickener in the aqueous solution. The enhanced air saturations using SCMC for the 1-D air Sparging experiment improved the degradative performance of gaseous oxidation agent (ozone) during air Sparging, as measured by the disappearance of fluorescence (fluorescein sodium salt). Based on the experimental evidence generated in this study, the addition of a thickener in the aqueous solution prior to air Sparging increased the degree of air saturation and the Sparging influence zone, and enhanced the remedial potential of SEAS for contaminated aquifers.
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changes in air flow patterns using surfactants and thickeners during air Sparging bench scale experiments
Journal of Contaminant Hydrology, 2015Co-Authors: Michael D AnnableAbstract:Abstract Air injected into an aquifer during air Sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air Sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air Sparging. Increased viscosity retarded the travel velocity of the air front during air Sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air Sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air Sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air Sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating.
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laboratory evaluation of surfactant enhanced air Sparging for perchloroethene source mass depletion from sand
Journal of Environmental Science and Health Part A-toxic\ hazardous Substances & Environmental Engineering, 2009Co-Authors: Michael D AnnableAbstract:Surfactant-enhanced air Sparging (SEAS) was evaluated in this laboratory-scale study to assess: (i) the removal efficiency of volatile contaminant from an aquifer model contrasted to conventional air Sparging; and (ii) the effect of mass removal of dense non-aqueous phase liquid (DNAPL) during air Sparging on the changes in aqueous flux of dissolved DNAPL. We conducted Sparging experiments to remove perchloroethene (PCE) sources from laboratory flow chambers packed with sand. PCE was emplaced in rectangular zones at three locations within the flow chamber. The resident water was supplemented with the anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), to reduce the surface tension of water, and then sparged with nitrogen gas at a constant flow rate of 0.12 L/min. It was found that SEAS was significantly more efficient than conventional air Sparging for removing PCE. For SEAS, about 78% and 75% of total PCE mass was depleted from the flow chamber at a surface tension of 52.2 dynes/cm (350 mg/L SDBS...
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changes in air saturation and air water interfacial area during surfactant enhanced air Sparging in saturated sand
Journal of Contaminant Hydrology, 2006Co-Authors: Kyongmin Choi, Jiwon Moon, Michael D AnnableAbstract:Abstract Reduction in the surface tension of groundwater, prior to air Sparging for removal of volatile organic contaminant from aquifer, can greatly enhance the air content and the extent of influence when air Sparging is implemented. However, detailed information on the functional relationship between water saturation, air–water contact area induced by air Sparging and the surface tension of water has not been available. In this study, the influence of adding water-soluble anionic surfactant (sodium dodecyl benzene sulfonate) into groundwater before air Sparging on the air–water interfacial area and water saturation was investigated using a laboratory-scale sand packed column. It was found that water saturation decreases with decreasing surface tension of water until it reaches a point where this trend is reversed so that water saturation increases with further decrease in the surface tension. The lowest water saturation of 0.58 was achieved at a surface tension of 45.4 dyn/cm, which is considered as the optimum surface tension for maximum de-saturation for the initially water-saturated sand used in this study. The air–water contact area generated in the sand column due to air Sparging was measured using a gaseous interfacial tracer, n -decane, and was found to monotonically increase with decreasing water saturation. The results of this study provide useful design information for surfactant-enhanced air Sparging removal of volatile contaminants from aquifers.
Michael W Laird - One of the best experts on this subject based on the ideXlab platform.
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air Sparging for prevention of antibody disulfide bond reduction in harvested cho cell culture fluid
Biotechnology and Bioengineering, 2015Co-Authors: Stefanie Khoo, Aline Do Minh, James Dvornicky, Melody Trexlerschmidt, Michael W LairdAbstract:During the scale-up of several Chinese Hamster Ovary (CHO) cell monoclonal antibody production processes, significant reduction of the antibody interchain disulfide bonds was observed. The reduction was correlated with excessive mechanical cell shear during the harvest operations. These antibody reduction events resulted in failed product specifications and the subsequent loss of the drug substance batches. Several methods were recently developed to prevent antibody reduction, including modifying the cell culture media, using pre- and post-harvest chemical additions to the cell culture fluid (CCF), lowering the pH, and air Sparging of the harvested CCF (HCCF). The work described in this paper further explores the option of HCCF air Sparging for preventing antibody reduction. Here, a small-scale model was developed using a 3-L bioreactor to mimic the conditions of a manufacturing-scale harvest vessel and was subsequently employed to evaluate several air Sparging strategies. In addition, these studies enabled further understanding of the relationships between cell lysis levels, oxygen consumption, and antibody reduction. Finally, the effectiveness of air Sparging for several CHO cell lines and the potential impact on product quality were assessed to demonstrate that air Sparging is an effective method in preventing antibody reduction. Biotechnol. Bioeng. 2015;112: 734–742. © 2014 Wiley Periodicals, Inc.
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air Sparging for prevention of antibody disulfide bond reduction in harvested cho cell culture fluid
Biotechnology and Bioengineering, 2015Co-Authors: Melissa Mun, Stefanie Khoo, Aline Do Minh, James Dvornicky, Melody Trexlerschmidt, Yunghsiang Kao, Michael W LairdAbstract:During the scale-up of several Chinese Hamster Ovary (CHO) cell monoclonal antibody production processes, significant reduction of the antibody interchain disulfide bonds was observed. The reduction was correlated with excessive mechanical cell shear during the harvest operations. These antibody reduction events resulted in failed product specifications and the subsequent loss of the drug substance batches. Several methods were recently developed to prevent antibody reduction, including modifying the cell culture media, using pre- and post-harvest chemical additions to the cell culture fluid (CCF), lowering the pH, and air Sparging of the harvested CCF (HCCF). The work described in this paper further explores the option of HCCF air Sparging for preventing antibody reduction. Here, a small-scale model was developed using a 3-L bioreactor to mimic the conditions of a manufacturing-scale harvest vessel and was subsequently employed to evaluate several air Sparging strategies. In addition, these studies enabled further understanding of the relationships between cell lysis levels, oxygen consumption, and antibody reduction. Finally, the effectiveness of air Sparging for several CHO cell lines and the potential impact on product quality were assessed to demonstrate that air Sparging is an effective method in preventing antibody reduction.
David C Stuckey - One of the best experts on this subject based on the ideXlab platform.
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effect of Sparging rate on permeate quality in a submerged anaerobic membrane bioreactor sambr treating leachate from the organic fraction of municipal solid waste ofmsw
Journal of Environmental Management, 2016Co-Authors: Antoine P Trzcinski, David C StuckeyAbstract:This paper focuses on the treatment of leachate from the organic fraction of municipal solid waste (OFMSW) in a submerged anaerobic membrane bioreactor (SAMBR). Operation of the SAMBR for this type of high strength wastewater was shown to be feasible at 5 days hydraulic retention time (HRT), 10 L min(-1) (LPM) biogas Sparging rate and membrane fluxes in the range of 3-7 L m(-2) hr(-1) (LMH). Under these conditions, more than 90% COD removal was achieved during 4 months of operation without chemical cleaning the membrane. When the Sparging rate was reduced to 2 LPM, the transmembrane pressure increased dramatically and the bulk soluble COD concentration increased due to a thicker fouling layer, while permeate soluble COD remained constant. Permeate soluble COD concentration increased by 20% when the Sparging rate increased to 10 LPM.
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the effect of Sparging rate on transmembrane pressure and critical flux in an anmbr
Journal of Environmental Management, 2015Co-Authors: R A Fox, David C StuckeyAbstract:Abstract Anaerobic membrane bioreactors (AnMBRs) have been shown to be successful units for the treatment of low strength wastewaters, however, the issue of membrane fouling is still a major problem in terms of economic viability. Biogas Sparging has been shown to reduce fouling substantially, and hence this study monitored the effect of biogas Sparging rate on an AnMBR. The critical flux under a Sparging rate of 6 l per minute (LPM) was found to be 11.8 l m −2 h −1 (LMH), however, membrane hysteresis was found to have an effect on the critical flux, and where the AnMBR had previously been operated with a 2 LPM Sparging rate, the critical flux fell to 7.2 LMH. The existence of a “critical Sparging rate” was also investigated under the condition that ‘there exists a Sparging rate beyond which any further decrease in Sparging rate will cause a dramatic rise in TMP’. For an AnMBR operating at a flux of 7.2 LMH the critical Sparging rate was found to be 4 LPM.
Johan Thuvander - One of the best experts on this subject based on the ideXlab platform.
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techno economic impact of air Sparging prior to purification of alkaline extracted wheat bran hemicelluloses by membrane filtration
Separation and Purification Technology, 2020Co-Authors: Johan ThuvanderAbstract:Abstract Air Sparging of alkaline-extracted wheat bran hemicelluloses prior to ultrafiltration has been shown to increase the flux. The techno-economic impact of air Sparging on the cost of concentration and purification of wheat bran hemicelluloses by ultrafiltration and diafiltration was studied in this work. Two alkaline hemicellulose solutions were purified until the conductivity of the diafiltration permeate was
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influence of air and nitrogen Sparging on flux during ultrafiltration of hemicelluloses extracted from wheat bran
Separation and Purification Technology, 2019Co-Authors: Johan Thuvander, Annsofi JonssonAbstract:Abstract Ultrafiltration can be used to concentrate arabinoxylan isolated from wheat bran. Prefiltration with diatomaceous earth and air Sparging during ultrafiltration of the alkaline hemicellulose solution were both found to increase the flux, while nitrogen Sparging had no effect. The flux of the untreated solution was 51 L/m2 h, while the flux after prefiltration of the solution with diatomaceous earth was 62 L/m2 h. After 5 h of air Sparging during ultrafiltration of the prefiltered solution the flux was 230 L/m2 h. However, Sparging the prefiltered solution with nitrogen gas had no effect on the flux. This shows that the increase in flux was not due to the reduction of concentration polarization by Sparging per se. Size-exclusion chromatography showed that Sparging with air caused a reduction in the size of hemicelluloses >100 kDa to 10–100 kDa, which is believed to be due to oxidative degradation of hemicelluloses. This size reduction of the hemicelluloses is likely the main cause of the increased flux. The retention of hemicelluloses during ultrafiltration with a ceramic membrane with a nominal cut-off of 10 kDa was 96% in all experiments, except at the end of the experiment with the prefiltered, air-sparged solution, when the retention decreased to 93% due to the size reduction of the hemicelluloses. Air Sparging seems to be an efficient flux enhancing method with limited negative influence on the molecular size of hemicelluloses.
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Reduction of energy demand by use of air Sparging during ultrafiltration of alkali-extracted wheat bran hemicelluloses
Chemical Engineering Research & Design, 2018Co-Authors: Johan Thuvander, Anders ArkellAbstract:Abstract The flux during membrane filtration can be enhanced by the use of a two-phase gas–liquid flow. This has been shown to be an energy-efficient alternative to increasing the cross-flow velocity. In this work, air Sparging was used to increase the flux during ultrafiltration of alkali-extracted wheat bran hemicelluloses. Batch filtration was performed in a pilot unit with a ceramic ultrafiltration membrane with a nominal cut-off of 10 kDa. Parametric studies with and without air Sparging were performed at temperatures of 30 °C, 50 °C and 80 °C and cross-flow velocities of 1, 3, 5 and 7 m/s. The limiting flux was not affected by air Sparging at 30 °C, while a slight increase was observed at 50 °C and a considerable increase was obtained at 80 °C. Air Sparging reduced the energy demand per m3 permeate produced during dead-end batch ultrafiltration at 80 °C and 1 m/s from 0.96 kWh/m3 to 0.51 kWh/m3.
