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W. Zimmerman

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J. B. (Jack) Owens

Idaho State University

Rasmus Grønfeldt Winther

University of California, Santa Cruz

Antonio Diéguez

Universidad de Málaga

Ricardo Martínez Esquivel

Universidad de Costa Rica

Aleksandr Koptev

Independent Scholar

Universiti Teknologi PETRONAS

Martina Ulvrova

Swiss Federal Institute of Technology (ETH) & University of Zurich

Lorenzo Magnani

University of Pavia

German Research Center for Artificial Intelligence

Pascale Rabault-Feuerhahn

Centre National de la Recherche Scientifique / French National Centre for Scientific Research

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Papers by W. Zimmerman

Inactivation combined with cell lysis ofPseudomonas putidausing a low pressure carbon dioxide microbubble technology

Journal of Chemical Technology & Biotechnology, 2017

BACKGROUND: Inactivation processes can be classified into non-thermal inactivation methods such a... more BACKGROUND: Inactivation processes can be classified into non-thermal inactivation methods such as ethylene oxide and-radiation, and thermal methods such as autoclaving. The ability of carbon dioxide enriched microbubbles to inactivate Pseudomonas putida suspended in physiological saline, as a non-thermal sterilisation method, was investigated in this study with many operational advantages over both traditional thermal and non-thermal sterilisation methods. RESULTS: Introducing carbon dioxide enriched microbubbles can achieve ∼2-Log reduction in the bacterial population after 90 min of treatment, addition of ethanol to the inactivation solution further enhanced the inactivation process to achieve 3, 2.5 and 3.5-Log reduction for 2%, 5% and 10 %(v/v) ethanol, respectively. A range of morphological changes was observed on Pseudomonas cells after each treatment, and these changes extended from changing cell shape from rod shape to coccus shape to severe lesions and cell death. Pseudomonas putida KT 2440 was used as a model of gram-negative bacteria. CONCLUSION: Using CO 2 enriched microbubbles technology has many advantages such as efficient energy consumption (no heat source), avoidance of toxic and corrosive reagents, and in situ treatment. In addition, many findings from this study could apply to other gram-negative bacteria.

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

AIChE Journal, 2018

A novel lignocellulosic biomass pretreatment reactor has been designed and tested to investigate ... more A novel lignocellulosic biomass pretreatment reactor has been designed and tested to investigate pretreatment efficacy of miscanthus grass. The reactor was designed to optimize the transfer of highly oxidative species produced by dielectric barrier discharge plasma to the liquid phase immediately after generation, by arranging close proximity of the plasma to the gas-liquid interface of microbubbles. The reactor produced a range of reactive oxygen species and reactive nitrogen species, and the rate of production depended on the power source duty cycle and the temperature of the plasma. Ozone and other oxidative species were dispersed efficiently using energy efficient microbubbles produced by fluidic oscillations. A 5% (w/w) miscanthus suspension pretreated for 3 h at 10% duty cycle yielded 0.5% acid soluble lignin release and 26% sugar release post hydrolysis with accelerated pretreatment toward the latter stages of the treatment demonstrating the potential of this approach as an alternative pretreatment method.

Microalgae biorefinery concept based on hydrothermal microwave pyrolysis

Green Chemistry, 2012

Fig.1S GC-MS analysis of products of microwave activated hydrolysis of cellulose silylated by TMS... more

Microbubbles Enhanced Synthetic Phorbol Ester Degradation By Ozonolysis

A phorbol-12-myristate-13-acetate (TPA) is a synthetic analogue of phorbol ester (PE), a natural ... more A phorbol-12-myristate-13-acetate (TPA) is a synthetic analogue of phorbol ester (PE), a natural toxic compound of Euphorbiaceae plant. The oil extracted from plants of this family is useful source for primarily biofuel. However this oil might also be used as a foodstuff due to its significant nutrition content. The limitations for utilizing the oil as a foodstuff are mainly due to a toxicity of PE. Currently, a majority of PE detoxification processes are expensive as include multi steps alcohol extraction sequence. Ozone is considered as a strong oxidative agent. It reacts with PE by attacking the carbon-carbon double bond of PE. This modification of PE molecular structure yields a non toxic ester with high lipid content. This report presents data on development of simple and cheap PE detoxification process with water application as a buffer and ozone as reactive component. The core of this new technique is an application for a new microscale plasma unit to ozone production and the...

Spreading of a Saturation Front of Heterogeneous Chemical Reaction Through an Aerosol Cloud

Научные Ведомости Белгородского Государственного Университета Серия Математика Физика, 2014

Design of an airlift loop bioreactor and pilot scales studies with fluidic oscillator induced microbubbles for growth of a microalgae Dunaliella salina

Applied Energy, 2011

This study was conducted to test the feasibility of growing microalgae on steel plant exhaust gas... more This study was conducted to test the feasibility of growing microalgae on steel plant exhaust gas, generated from the combustion of offgases from steel processing, which has a high CO 2 content. Two field trials of batch algal biomass growth, mediated by microbubble transfer processes in an airlift loop bioreactor showed only steady growth of biomass with 100% survival rate. The gas analysis of CO 2 uptake in the 2200 liter bioreactor showed a specific uptake rate of 0.1g / liter / hr, an average 14% of the CO 2 available in the exhaust gas with a 23% composition of CO 2. This uptake led to a steady production of chlorophyll and total lipid constituency in the bioreactor, and an accelerating exponential growth rate of biomass, with a top doubling time of 1.8 days. The gas analysis also showed anti-correlation of CO 2 uptake and O 2 production, which along with the apparent stripping of the O 2 to the equilibrium level by the microbubbles, strongly suggests that the bioreactor is not mass transfer limited, nor O 2 inhibited. Removing O 2 inhibition results in high growth rates and high density of biomass.

Efficient Compact Micro Dielectric Barrier Discharge (DBD) Plasma Reactor for Ozone Generation for Industrial Application in Liquid and Gas Phase Systems

Ozone is well known as a powerful fast reaction rate oxidant. The ozone based processes produce n... more Ozone is well known as a powerful fast reaction rate oxidant. The ozone based processes produce no by-product left as a non-reacted ozone returns back to the original oxygen molecule. Therefore an application of ozone is widely accepted as one of the main directions for a sustainable and clean technologies development. There are number of technologies require ozone to be delivered to specific points of a production network or reactors construction. Due to space constrains, high reactivity and short life time of ozone the use of ozone generators even of a bench top scale is practically limited. This requires development of mini/micro scale ozone generator which can be directly incorporated into production units. Our report presents a feasibility study of a new micro scale rector for ozone generation (MROG). Data on MROG calibration and indigo decomposition at different operation conditions are presented. At selected operation conditions with residence time of 0.25 s the process of oz...

An inverse methodology for the rheology of a power-law non-Newtonian fluid

The current paper presents a novel methodology for calculating the rheological para-meters for di... more The current paper presents a novel methodology for calculating the rheological para-meters for dilute aqueous solutions of a power-law non-Newtonian fluid, xanthan gum (XG). Previous studies have verified the fidelity of finite-element modelling of the Navier—Stokes equations for reproducing the velocity fields of XG solutions in a microfluidic T-junction with experimental observations obtained using micron resolution particle image velocimetry (μ-PIV). As the pressure-driven fluid is forced to turn the corner of the T-junction, a range of shear rates, and therefore viscosities, are produced within the flow system. Thus, a setup that potentially establishes the rheological profile of XG from a single experiment is selected. An inverse method based on finding the mapping between the statistical moments of the velocity field and the constitutive parameters of the viscosity profile demonstrated that such a system could potentially be used for the design of an efficient microfluidic rheometer. However, μ-PIV technology is expensive and the equipment is bulky. The current paper investigates whether different flow features could be used to establish the rheological profile.

Our adventure with Manuel

My year with Manuel

It really started 20 months earlier, when Manuel gave a seminar to the Homsy research group at St... more It really started 20 months earlier, when Manuel gave a seminar to the Homsy research group at Stanford University. Manuel captivated me with his description of the “solitary” wave and the new nonlinear wave equation he was deriving in active media. He came to my seminar not long after, where I was declaring my intention to finish my doctorate soon. I considered myself a new breed of fluid dynamicist—a computational modeller. Manuel could see the utility of our collaboration, so he invited me to Madrid.

Modelling accidental releases of dangerous gases into the lower troposphere from mobile sources

Process Safety and Environmental Protection, 2008

The article reports the results of different methods of modelling releases and dispersion of dang... more The article reports the results of different methods of modelling releases and dispersion of dangerous gases or vapours in cases of major accidents from road and rail transportation in urban zones. Transport accidents of dangerous substances are increasingly frequent and can cause serious injuries in densely inhabited areas or pollution of the environment. For quantitative risk assessment and mitigation planning, consequence modelling is necessary. The modelling of dangerous substance dispersion by standard methods does not fully represent the behaviour of toxic or flammable clouds in obstructed areas such as street canyons. Therefore the predictions from common software packages as ALOHA, EFFECTS, TerEx should be augmented with CFD models or physical modelling in aerodynamic tunnels, and further studies are planned to do this. The goal of this article is to present the results of the first approach of modelling using these standard methods and to demonstrate the importance of the next development stage in the area of transport accident modelling of releases and dispersions of dangerous substances in urban zones in cases of major accident or terrorist attacks.

Computational Modeling for Fluid Flow and Interfacial Transport . By W. S HYY . Elsevier, 1994. 504 pp. ISBN 0-444-81760-3. Dfl 395

Journal of Fluid Mechanics, 1995

GMT computational modeling for fluid flow pdf-Computational fluid dynamics (CFD) is a branch of f... more GMT computational modeling for fluid flow pdf-Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Sun, 06 Jan 2019 13:01:00 GMT Computational fluid dynamics-Wikipedia-Passage Sysflow is 1D computational fluid dynamics software flow simulation and system analysis. Virtually any flow network system and/or subsystem can be modeled. Sat, 05 Jan 2019 00:45:00 GMT 1D computational fluid dynamics software-Pipe Flow ...-In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluidsâ€"liquids and gases. It has several subdisciplines ... Mon, 07 Jan 2019 19:41:00 GMT Fluid dynamics-Wikipedia-7 Multiphase flow regimes â€¢ User must know a priori the characteristics of the flow. â€¢ Flow regime, e.g. bubbly flow, slug flow, annular flow, etc. Mon, 07 Jan 2019 13:36:00 GMT Lecture 14-Multiphase Flows Applied Computational Fluid ...-NPTEL provides E-learning through online Web and Video courses various streams. Mon,

Effects of transport and phase equilibrium on fast, nearly irreversible reactive extraction

Chemical Engineering Science, 2007

Integration of reaction and separation can be exploited to drive reversible reactions in the dire... more Integration of reaction and separation can be exploited to drive reversible reactions in the direction of the desired product using multiphase flow contacting. In the case of nearly irreversible, fast reactions, however, the dynamics of the product have little influence on the reactor efficiency in say liquid-liquid reactive extraction. A similar intensification in reaction efficiency to reactive separation can be achieved by exploiting phase equilibrium or asymmetry in mass transfer rates of the reactants. Here, a model for two-layer biphasic flow and homogeneous reaction is proposed for co-current reactive extraction, demonstrating that localization and intensification of reaction occurs in the region between the entrance and crossover. Crossover occurs if the reactant in stoichiometric deficit preferentially populates the reacting phase due to sufficient imbalance in either mass transfer coefficients or phase equilibrium. We develop an infinite Peclet number (convection dominates over bulk diffusion) model that indicates that crossover occurs when

Kinematic model of bubble motion in a flotation froth

Powder Technology, 1996

A kinematic model for bubble motion in a flotation froth is proposed. The model describes bubble ... more A kinematic model for bubble motion in a flotation froth is proposed. The model describes bubble trajectories in a two-dimensional vertical section of the froth phase of a flotation cell. If the viscosity and permeability of the froth is constant over the field, then the motion of bubbles is irrotational and Laplace's equation can be used to describe the setamline

Efficiency of an aerator driven by fluidic oscillation. Part II: Pilot scale trials with flexible membrane diffusers

by Olumuyiwa Omotowa and W. Zimmerman

eyrie.shef.ac.uk

Pilot plant aeration performance with microbubble generation by a novel fluidic oscillator driven... more Pilot plant aeration performance with microbubble generation by a novel fluidic oscillator driven approach is studied, with a view to identifying the key design elements and their differences from standard approaches to wastewater treatment. The microbubble generation mechanism has been shown to achieve high mass transfer rates by the decrease of the bubble diameter, by hydrodynamic stabilization that avoids coalescence increasing the bubble diameter, and by longer residence times offsetting slower convection. The fluidic oscillator approach also decreases the friction losses in pipe networks and in nozzles / diffusers due to boundary layer disruption, so there is actually an energetic consumption savings in using this approach over steady flow. These dual advantages make the microbubble generation approach a promising component of a diffuser network for wastewater treatment. The clear water trials show that there is a best configuration for fluidic oscillation to accelerate the oxygen transfer efficiency in the initial stages of transfer, particularly while the DO concentration level is less than 3mg/l which is the industrially important regime. One measure of the accelerated oxygen transfer, the dosage, shows a 3-4 fold improvement over the control and the standard design, respectively. The best power consumption decrease found in this oscillatory configuration is 18%. Furthermore, this configuration is at 83% of the designed volumetric air flow rate for conventional operation of the diffuser network.

Inactivation combined with cell lysis ofPseudomonas putidausing a low pressure carbon dioxide microbubble technology

Journal of Chemical Technology & Biotechnology, 2017

BACKGROUND: Inactivation processes can be classified into non-thermal inactivation methods such a... more BACKGROUND: Inactivation processes can be classified into non-thermal inactivation methods such as ethylene oxide and-radiation, and thermal methods such as autoclaving. The ability of carbon dioxide enriched microbubbles to inactivate Pseudomonas putida suspended in physiological saline, as a non-thermal sterilisation method, was investigated in this study with many operational advantages over both traditional thermal and non-thermal sterilisation methods. RESULTS: Introducing carbon dioxide enriched microbubbles can achieve ∼2-Log reduction in the bacterial population after 90 min of treatment, addition of ethanol to the inactivation solution further enhanced the inactivation process to achieve 3, 2.5 and 3.5-Log reduction for 2%, 5% and 10 %(v/v) ethanol, respectively. A range of morphological changes was observed on Pseudomonas cells after each treatment, and these changes extended from changing cell shape from rod shape to coccus shape to severe lesions and cell death. Pseudomonas putida KT 2440 was used as a model of gram-negative bacteria. CONCLUSION: Using CO 2 enriched microbubbles technology has many advantages such as efficient energy consumption (no heat source), avoidance of toxic and corrosive reagents, and in situ treatment. In addition, many findings from this study could apply to other gram-negative bacteria.

Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass

AIChE Journal, 2018

A novel lignocellulosic biomass pretreatment reactor has been designed and tested to investigate ... more A novel lignocellulosic biomass pretreatment reactor has been designed and tested to investigate pretreatment efficacy of miscanthus grass. The reactor was designed to optimize the transfer of highly oxidative species produced by dielectric barrier discharge plasma to the liquid phase immediately after generation, by arranging close proximity of the plasma to the gas-liquid interface of microbubbles. The reactor produced a range of reactive oxygen species and reactive nitrogen species, and the rate of production depended on the power source duty cycle and the temperature of the plasma. Ozone and other oxidative species were dispersed efficiently using energy efficient microbubbles produced by fluidic oscillations. A 5% (w/w) miscanthus suspension pretreated for 3 h at 10% duty cycle yielded 0.5% acid soluble lignin release and 26% sugar release post hydrolysis with accelerated pretreatment toward the latter stages of the treatment demonstrating the potential of this approach as an alternative pretreatment method.

Microalgae biorefinery concept based on hydrothermal microwave pyrolysis

Green Chemistry, 2012

Fig.1S GC-MS analysis of products of microwave activated hydrolysis of cellulose silylated by TMS... more

Microbubbles Enhanced Synthetic Phorbol Ester Degradation By Ozonolysis

A phorbol-12-myristate-13-acetate (TPA) is a synthetic analogue of phorbol ester (PE), a natural ... more A phorbol-12-myristate-13-acetate (TPA) is a synthetic analogue of phorbol ester (PE), a natural toxic compound of Euphorbiaceae plant. The oil extracted from plants of this family is useful source for primarily biofuel. However this oil might also be used as a foodstuff due to its significant nutrition content. The limitations for utilizing the oil as a foodstuff are mainly due to a toxicity of PE. Currently, a majority of PE detoxification processes are expensive as include multi steps alcohol extraction sequence. Ozone is considered as a strong oxidative agent. It reacts with PE by attacking the carbon-carbon double bond of PE. This modification of PE molecular structure yields a non toxic ester with high lipid content. This report presents data on development of simple and cheap PE detoxification process with water application as a buffer and ozone as reactive component. The core of this new technique is an application for a new microscale plasma unit to ozone production and the...

Spreading of a Saturation Front of Heterogeneous Chemical Reaction Through an Aerosol Cloud

Научные Ведомости Белгородского Государственного Университета Серия Математика Физика, 2014

Design of an airlift loop bioreactor and pilot scales studies with fluidic oscillator induced microbubbles for growth of a microalgae Dunaliella salina

Applied Energy, 2011

This study was conducted to test the feasibility of growing microalgae on steel plant exhaust gas... more This study was conducted to test the feasibility of growing microalgae on steel plant exhaust gas, generated from the combustion of offgases from steel processing, which has a high CO 2 content. Two field trials of batch algal biomass growth, mediated by microbubble transfer processes in an airlift loop bioreactor showed only steady growth of biomass with 100% survival rate. The gas analysis of CO 2 uptake in the 2200 liter bioreactor showed a specific uptake rate of 0.1g / liter / hr, an average 14% of the CO 2 available in the exhaust gas with a 23% composition of CO 2. This uptake led to a steady production of chlorophyll and total lipid constituency in the bioreactor, and an accelerating exponential growth rate of biomass, with a top doubling time of 1.8 days. The gas analysis also showed anti-correlation of CO 2 uptake and O 2 production, which along with the apparent stripping of the O 2 to the equilibrium level by the microbubbles, strongly suggests that the bioreactor is not mass transfer limited, nor O 2 inhibited. Removing O 2 inhibition results in high growth rates and high density of biomass.

Efficient Compact Micro Dielectric Barrier Discharge (DBD) Plasma Reactor for Ozone Generation for Industrial Application in Liquid and Gas Phase Systems

Ozone is well known as a powerful fast reaction rate oxidant. The ozone based processes produce n... more Ozone is well known as a powerful fast reaction rate oxidant. The ozone based processes produce no by-product left as a non-reacted ozone returns back to the original oxygen molecule. Therefore an application of ozone is widely accepted as one of the main directions for a sustainable and clean technologies development. There are number of technologies require ozone to be delivered to specific points of a production network or reactors construction. Due to space constrains, high reactivity and short life time of ozone the use of ozone generators even of a bench top scale is practically limited. This requires development of mini/micro scale ozone generator which can be directly incorporated into production units. Our report presents a feasibility study of a new micro scale rector for ozone generation (MROG). Data on MROG calibration and indigo decomposition at different operation conditions are presented. At selected operation conditions with residence time of 0.25 s the process of oz...

An inverse methodology for the rheology of a power-law non-Newtonian fluid

The current paper presents a novel methodology for calculating the rheological para-meters for di... more The current paper presents a novel methodology for calculating the rheological para-meters for dilute aqueous solutions of a power-law non-Newtonian fluid, xanthan gum (XG). Previous studies have verified the fidelity of finite-element modelling of the Navier—Stokes equations for reproducing the velocity fields of XG solutions in a microfluidic T-junction with experimental observations obtained using micron resolution particle image velocimetry (μ-PIV). As the pressure-driven fluid is forced to turn the corner of the T-junction, a range of shear rates, and therefore viscosities, are produced within the flow system. Thus, a setup that potentially establishes the rheological profile of XG from a single experiment is selected. An inverse method based on finding the mapping between the statistical moments of the velocity field and the constitutive parameters of the viscosity profile demonstrated that such a system could potentially be used for the design of an efficient microfluidic rheometer. However, μ-PIV technology is expensive and the equipment is bulky. The current paper investigates whether different flow features could be used to establish the rheological profile.

Our adventure with Manuel

My year with Manuel

It really started 20 months earlier, when Manuel gave a seminar to the Homsy research group at St... more It really started 20 months earlier, when Manuel gave a seminar to the Homsy research group at Stanford University. Manuel captivated me with his description of the “solitary” wave and the new nonlinear wave equation he was deriving in active media. He came to my seminar not long after, where I was declaring my intention to finish my doctorate soon. I considered myself a new breed of fluid dynamicist—a computational modeller. Manuel could see the utility of our collaboration, so he invited me to Madrid.

Modelling accidental releases of dangerous gases into the lower troposphere from mobile sources

Process Safety and Environmental Protection, 2008

The article reports the results of different methods of modelling releases and dispersion of dang... more The article reports the results of different methods of modelling releases and dispersion of dangerous gases or vapours in cases of major accidents from road and rail transportation in urban zones. Transport accidents of dangerous substances are increasingly frequent and can cause serious injuries in densely inhabited areas or pollution of the environment. For quantitative risk assessment and mitigation planning, consequence modelling is necessary. The modelling of dangerous substance dispersion by standard methods does not fully represent the behaviour of toxic or flammable clouds in obstructed areas such as street canyons. Therefore the predictions from common software packages as ALOHA, EFFECTS, TerEx should be augmented with CFD models or physical modelling in aerodynamic tunnels, and further studies are planned to do this. The goal of this article is to present the results of the first approach of modelling using these standard methods and to demonstrate the importance of the next development stage in the area of transport accident modelling of releases and dispersions of dangerous substances in urban zones in cases of major accident or terrorist attacks.

Computational Modeling for Fluid Flow and Interfacial Transport . By W. S HYY . Elsevier, 1994. 504 pp. ISBN 0-444-81760-3. Dfl 395

Journal of Fluid Mechanics, 1995

GMT computational modeling for fluid flow pdf-Computational fluid dynamics (CFD) is a branch of f... more GMT computational modeling for fluid flow pdf-Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Sun, 06 Jan 2019 13:01:00 GMT Computational fluid dynamics-Wikipedia-Passage Sysflow is 1D computational fluid dynamics software flow simulation and system analysis. Virtually any flow network system and/or subsystem can be modeled. Sat, 05 Jan 2019 00:45:00 GMT 1D computational fluid dynamics software-Pipe Flow ...-In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluidsâ€"liquids and gases. It has several subdisciplines ... Mon, 07 Jan 2019 19:41:00 GMT Fluid dynamics-Wikipedia-7 Multiphase flow regimes â€¢ User must know a priori the characteristics of the flow. â€¢ Flow regime, e.g. bubbly flow, slug flow, annular flow, etc. Mon, 07 Jan 2019 13:36:00 GMT Lecture 14-Multiphase Flows Applied Computational Fluid ...-NPTEL provides E-learning through online Web and Video courses various streams. Mon,

Effects of transport and phase equilibrium on fast, nearly irreversible reactive extraction

Chemical Engineering Science, 2007

Integration of reaction and separation can be exploited to drive reversible reactions in the dire... more Integration of reaction and separation can be exploited to drive reversible reactions in the direction of the desired product using multiphase flow contacting. In the case of nearly irreversible, fast reactions, however, the dynamics of the product have little influence on the reactor efficiency in say liquid-liquid reactive extraction. A similar intensification in reaction efficiency to reactive separation can be achieved by exploiting phase equilibrium or asymmetry in mass transfer rates of the reactants. Here, a model for two-layer biphasic flow and homogeneous reaction is proposed for co-current reactive extraction, demonstrating that localization and intensification of reaction occurs in the region between the entrance and crossover. Crossover occurs if the reactant in stoichiometric deficit preferentially populates the reacting phase due to sufficient imbalance in either mass transfer coefficients or phase equilibrium. We develop an infinite Peclet number (convection dominates over bulk diffusion) model that indicates that crossover occurs when

Kinematic model of bubble motion in a flotation froth

Powder Technology, 1996

A kinematic model for bubble motion in a flotation froth is proposed. The model describes bubble ... more A kinematic model for bubble motion in a flotation froth is proposed. The model describes bubble trajectories in a two-dimensional vertical section of the froth phase of a flotation cell. If the viscosity and permeability of the froth is constant over the field, then the motion of bubbles is irrotational and Laplace's equation can be used to describe the setamline

Efficiency of an aerator driven by fluidic oscillation. Part II: Pilot scale trials with flexible membrane diffusers

by Olumuyiwa Omotowa and W. Zimmerman

eyrie.shef.ac.uk

Pilot plant aeration performance with microbubble generation by a novel fluidic oscillator driven... more Pilot plant aeration performance with microbubble generation by a novel fluidic oscillator driven approach is studied, with a view to identifying the key design elements and their differences from standard approaches to wastewater treatment. The microbubble generation mechanism has been shown to achieve high mass transfer rates by the decrease of the bubble diameter, by hydrodynamic stabilization that avoids coalescence increasing the bubble diameter, and by longer residence times offsetting slower convection. The fluidic oscillator approach also decreases the friction losses in pipe networks and in nozzles / diffusers due to boundary layer disruption, so there is actually an energetic consumption savings in using this approach over steady flow. These dual advantages make the microbubble generation approach a promising component of a diffuser network for wastewater treatment. The clear water trials show that there is a best configuration for fluidic oscillation to accelerate the oxygen transfer efficiency in the initial stages of transfer, particularly while the DO concentration level is less than 3mg/l which is the industrially important regime. One measure of the accelerated oxygen transfer, the dosage, shows a 3-4 fold improvement over the control and the standard design, respectively. The best power consumption decrease found in this oscillatory configuration is 18%. Furthermore, this configuration is at 83% of the designed volumetric air flow rate for conventional operation of the diffuser network.