This document discusses heat transfer and mass transfer concepts relevant to fermentation processes. It covers two main applications of heat transfer in bioreactors: sterilization of medium and temperature control during operation. Several heat exchanger configurations are discussed along with their pros and cons. Key concepts of mass transfer such as film theory, convective mass transfer, and the steps of oxygen transfer from a gas bubble to a cell are also summarized. Common unit operations used downstream of fermentation like filtration, centrifugation, and cell disruption methods are briefly introduced.
Heat is generated during fermentation that must be controlled. Common heat transfer configurations for bioreactors include jacketed vessels, internal coils, and external heat exchangers. External heat exchangers are best for heat transfer but require careful control of sterility and oxygen transfer. Internal coils can interfere with mixing and cleaning. Mass transfer in fermentation involves the diffusion of gases like oxygen across phase boundaries according to Fick's law and two-film theory. Downstream processing after fermentation includes steps like filtration, centrifugation, chromatography, and crystallization to isolate and purify products.
This document discusses heat and mass transfer concepts relevant to fermentation processes. It covers two main applications of heat transfer: sterilization of medium and temperature control during operation. Several heat exchanger configurations are described along with their pros and cons. Mass transfer concepts like Fick's law of diffusion and film theory are introduced. The document also analyzes the steps involved in oxygen transfer from gas bubbles to cells and the mass transfer resistances in bioreactors. Finally, common downstream processing unit operations like filtration and centrifugation are briefly described.
This document provides an overview of bioreactors. It begins with an introduction that defines bioreactors as engineered systems that support biologically active environments. It then discusses the role of bioreactors in biotechnology and the growth of microorganisms. The document proceeds to classify bioreactors into suspended growth and biofilm types. It provides examples of different bioreactor arrangements and discusses mass balances in bioreactors. It concludes by covering applications of bioreactors in wastewater treatment.
This document discusses aeration and agitation in fermentation processes. It defines aeration as the supply of oxygen to meet cellular demands, which is achieved through a sparger system. Agitation is defined as the uniform suspension of microbial cells through mixing the liquid, gas, and solid phases. The key functions of agitation are to distribute nutrients and gases, disperse bubbles, and diffuse materials while maintaining cells in suspension. Factors that impact oxygen transfer rates and the kLa value are also discussed.
Trickle-bed reactors are solid-liquid-gas contacting devices where liquid flows downward over a packed bed of catalyst particles. Gas can flow concurrently or countercurrently through the bed. Liquid forms thin films over catalyst particles. Species transport and reaction involve multiple steps: from gas to liquid interface, interface to bulk liquid, bulk liquid to catalyst surface, diffusion within catalyst pellet. Trickle beds are useful for three-phase reactions like hydrodesulfurization but can develop hot spots or channeling.
This presentation gives all the required information about pack bed bioreactor, including, advantages, disadvantages, applications and even how to overcome the disadvantages. Packed bed bioreactor is the major type of bioreactor used in waste water treatment as it involves the usage of catalyst. There are different types of packed bed bioreactors and they are used according to the desired product. There is picture representation and also tabular form of differentiation.
I have also mentioned the references at the end.
1. Bioreactors must be capable of aseptic operation for long periods of time while meeting containment regulations.
2. They must provide adequate aeration and agitation to meet microbial metabolic needs without damaging cells or causing excessive foaming.
3. Power consumption should be minimized while temperature is controlled during sterilization and fermentation.
Advance separation technology , chemical Engineering Short-Path-Distillation....savan51
## Short Path Distillation: A Deep Dive (Around 1500 Words)
Short path distillation (SPD) is a highly versatile technique for purifying and separating heat-sensitive compounds. Unlike traditional distillation methods, SPD operates under reduced pressure, significantly lowering the boiling points of liquids. This allows for the gentle and efficient purification of volatile organic compounds (VOCs), pharmaceuticals, natural products, and other delicate materials that might decompose at high temperatures.
This in-depth exploration delves into the world of short path distillation, covering its principles, components, operational procedures, applications, and advantages.
### Unveiling the Principles: The Science Behind Short Path Distillation
The core principle of SPD lies in **manipulating pressure** to achieve lower boiling points. By reducing the pressure within the distillation chamber, the energy required for a liquid to transition into a vapor state decreases. This allows for the distillation of heat-sensitive compounds at much lower temperatures compared to traditional methods at atmospheric pressure.
Here's a breakdown of the key factors at play:
* **Vapor Pressure:** Every liquid has a specific vapor pressure, which is the pressure exerted by its vapor when in equilibrium with the liquid at a given temperature. As temperature increases, the vapor pressure also rises.
* **Reduced Pressure:** In SPD, a vacuum pump is employed to significantly lower the pressure inside the distillation chamber. This reduction in pressure directly impacts the vapor pressure of the liquid mixture.
* **Lower Boiling Points:** With a lower vapor pressure required for boiling under reduced pressure, the boiling point of the liquid mixture also decreases. This allows for the gentle distillation of components without subjecting them to high temperatures that could potentially lead to decomposition.
The efficiency of SPD hinges on two additional factors:
* **Fractional Distillation:** Short path distillation often incorporates a **fractionating column** packed with a specialized material like glass beads or ceramic rings. This column provides additional surface area for vapor-liquid contact, enhancing the separation of different components within the mixture based on their relative boiling points.
* **Condensation:** The vaporized components travel upwards in the distillation flask and encounter a condenser cooled by a circulating coolant, typically water or a chilled liquid. As the vapors come into contact with the cold condenser, they condense back into their liquid forms and collect in a receiving flask.
### The Anatomy of an SPD System: Essential Components
A short path distillation system comprises several key components working in concert to achieve efficient purification:
* **Distillation Flask:** This round-bottomed flask, typically made of borosilicate glass due to its heat resistance and chemical compatibility, holds the liquid mixture to be dis
Heat is generated during fermentation that must be controlled. Common heat transfer configurations for bioreactors include jacketed vessels, internal coils, and external heat exchangers. External heat exchangers are best for heat transfer but require careful control of sterility and oxygen transfer. Internal coils can interfere with mixing and cleaning. Mass transfer in fermentation involves the diffusion of gases like oxygen across phase boundaries according to Fick's law and two-film theory. Downstream processing after fermentation includes steps like filtration, centrifugation, chromatography, and crystallization to isolate and purify products.
This document discusses heat and mass transfer concepts relevant to fermentation processes. It covers two main applications of heat transfer: sterilization of medium and temperature control during operation. Several heat exchanger configurations are described along with their pros and cons. Mass transfer concepts like Fick's law of diffusion and film theory are introduced. The document also analyzes the steps involved in oxygen transfer from gas bubbles to cells and the mass transfer resistances in bioreactors. Finally, common downstream processing unit operations like filtration and centrifugation are briefly described.
This document provides an overview of bioreactors. It begins with an introduction that defines bioreactors as engineered systems that support biologically active environments. It then discusses the role of bioreactors in biotechnology and the growth of microorganisms. The document proceeds to classify bioreactors into suspended growth and biofilm types. It provides examples of different bioreactor arrangements and discusses mass balances in bioreactors. It concludes by covering applications of bioreactors in wastewater treatment.
This document discusses aeration and agitation in fermentation processes. It defines aeration as the supply of oxygen to meet cellular demands, which is achieved through a sparger system. Agitation is defined as the uniform suspension of microbial cells through mixing the liquid, gas, and solid phases. The key functions of agitation are to distribute nutrients and gases, disperse bubbles, and diffuse materials while maintaining cells in suspension. Factors that impact oxygen transfer rates and the kLa value are also discussed.
Trickle-bed reactors are solid-liquid-gas contacting devices where liquid flows downward over a packed bed of catalyst particles. Gas can flow concurrently or countercurrently through the bed. Liquid forms thin films over catalyst particles. Species transport and reaction involve multiple steps: from gas to liquid interface, interface to bulk liquid, bulk liquid to catalyst surface, diffusion within catalyst pellet. Trickle beds are useful for three-phase reactions like hydrodesulfurization but can develop hot spots or channeling.
This presentation gives all the required information about pack bed bioreactor, including, advantages, disadvantages, applications and even how to overcome the disadvantages. Packed bed bioreactor is the major type of bioreactor used in waste water treatment as it involves the usage of catalyst. There are different types of packed bed bioreactors and they are used according to the desired product. There is picture representation and also tabular form of differentiation.
I have also mentioned the references at the end.
1. Bioreactors must be capable of aseptic operation for long periods of time while meeting containment regulations.
2. They must provide adequate aeration and agitation to meet microbial metabolic needs without damaging cells or causing excessive foaming.
3. Power consumption should be minimized while temperature is controlled during sterilization and fermentation.
Advance separation technology , chemical Engineering Short-Path-Distillation....savan51
## Short Path Distillation: A Deep Dive (Around 1500 Words)
Short path distillation (SPD) is a highly versatile technique for purifying and separating heat-sensitive compounds. Unlike traditional distillation methods, SPD operates under reduced pressure, significantly lowering the boiling points of liquids. This allows for the gentle and efficient purification of volatile organic compounds (VOCs), pharmaceuticals, natural products, and other delicate materials that might decompose at high temperatures.
This in-depth exploration delves into the world of short path distillation, covering its principles, components, operational procedures, applications, and advantages.
### Unveiling the Principles: The Science Behind Short Path Distillation
The core principle of SPD lies in **manipulating pressure** to achieve lower boiling points. By reducing the pressure within the distillation chamber, the energy required for a liquid to transition into a vapor state decreases. This allows for the distillation of heat-sensitive compounds at much lower temperatures compared to traditional methods at atmospheric pressure.
Here's a breakdown of the key factors at play:
* **Vapor Pressure:** Every liquid has a specific vapor pressure, which is the pressure exerted by its vapor when in equilibrium with the liquid at a given temperature. As temperature increases, the vapor pressure also rises.
* **Reduced Pressure:** In SPD, a vacuum pump is employed to significantly lower the pressure inside the distillation chamber. This reduction in pressure directly impacts the vapor pressure of the liquid mixture.
* **Lower Boiling Points:** With a lower vapor pressure required for boiling under reduced pressure, the boiling point of the liquid mixture also decreases. This allows for the gentle distillation of components without subjecting them to high temperatures that could potentially lead to decomposition.
The efficiency of SPD hinges on two additional factors:
* **Fractional Distillation:** Short path distillation often incorporates a **fractionating column** packed with a specialized material like glass beads or ceramic rings. This column provides additional surface area for vapor-liquid contact, enhancing the separation of different components within the mixture based on their relative boiling points.
* **Condensation:** The vaporized components travel upwards in the distillation flask and encounter a condenser cooled by a circulating coolant, typically water or a chilled liquid. As the vapors come into contact with the cold condenser, they condense back into their liquid forms and collect in a receiving flask.
### The Anatomy of an SPD System: Essential Components
A short path distillation system comprises several key components working in concert to achieve efficient purification:
* **Distillation Flask:** This round-bottomed flask, typically made of borosilicate glass due to its heat resistance and chemical compatibility, holds the liquid mixture to be dis
A batch reactor undergoes a controlled chemical reaction within a contained vessel. Reactants are added at the start and nothing is added or removed until the reaction is complete. Semi-batch reactors are similar but allow reactants or products to be continuously added or removed during the reaction. Batch reactors are useful for small scale or specialized productions like pharmaceuticals due to their flexibility, but they have higher operating costs than continuous reactors.
This document discusses different types of bioreactors. It begins by defining a bioreactor as an engineered device that supports a biologically active environment. It then classifies bioreactors as either suspended growth or biofilm reactors. The main types of bioreactors discussed are batch, continuous stirred-tank (CSTR), plug flow, packed bed, fluidized bed, and trickling filters. Applications mentioned include waste water treatment, food production, and reducing air pollutants. The document provides details on the operation and uses of these various bioreactor configurations.
This presentation provides an overview of bubble column reactors. It begins with an introduction that defines a bubble column reactor as a cylindrical vessel with a gas distributor at the bottom used for multiphase contact and reactions. The presentation then covers the theory of bubble column operation, design equations for parameters like superficial gas velocity and gas holdup, applications in chemical processes, and advantages like good heat and mass transfer with low costs and no moving parts.
This document summarizes key aspects of bioreactor design and operation. It describes common bioreactor configurations like stirred tank, bubble column, airlift, fluidized bed, and packed bed reactors. Design features are discussed like ports for sensors and gas sparging. Sterilization methods like steam sterilization in-place and clean-in-place procedures using alkaline and water rinses are outlined. Mass transfer processes and considerations for sterile operation are also briefly covered.
An insight into spray pulsed reactor through mathematical modeling of catalyt...Siluvai Antony Praveen
This document presents a mathematical model developed to study the impact of nozzle-catalyst distance and bulk gas temperature on the conversion and hydrogen evolution rate in a spray pulse reactor for the catalytic dehydrogenation of cyclohexane. The model was able to predict the effects of reactor configuration and operating parameters on conversion and evolution rate with over 90% accuracy. Reactor optimization analysis identified an optimal design of 5 cm nozzle-catalyst distance and 50°C bulk gas temperature, which was predicted to increase conversion from approximately 32% to 74%. The model provides a means to design endothermic heterogeneous catalytic reactions in spray pulse reactors.
The experiment studied the effect of temperature on the saponification reaction of ethyl acetate and sodium hydroxide in a batch reactor. Calibration curves were plotted at different temperatures to determine conductivity and conversion levels. Reactants were added to a jacketed reactor and stirred at 30°C and 50°C, with conductivity readings recorded. The data showed lower temperatures resulted in higher conversions as evidenced by lower conductivity readings. Batch reactors are useful for small-scale testing but have high operating costs and variable product quality compared to continuous reactors.
1) The document summarizes a study on the hydrodynamics of a semi-fluidized bed reactor using internals. Experiments were conducted with varying particle size, bed height, liquid velocity, and internals.
2) The minimum and maximum semi-fluidization velocities increased with larger particle size, higher bed expansion ratio, and use of internals. Pressure drop also rose with these factors.
3) Internals enhanced mixing and accelerated packed bed formation once minimum fluidization occurred, though a higher initial velocity was needed due to restricted particle motion. The study provides insight into optimizing semi-fluidized bed reactor efficiency through internals design.
The document discusses oxygen transfer in aerobic fermentation processes. It states that the majority of fermentation processes require oxygen, which has low solubility in water. For efficient oxygen transfer, dissolved oxygen must be continuously supplied to microorganisms at a rate equal to their demand. Key factors that influence oxygen transfer rate include bubble size, agitation intensity, viscosity, foaming, and vessel geometry. Equations are provided to characterize oxygen transfer rates and model maximum cell densities supported by reactors based on process conditions. Scale-up of fermentation processes requires matching critical environmental parameters like dissolved oxygen levels between small and large scales.
Biological and Advanced Water Treatment.pptxYalelet Abera
Micro-organisms play an essential role in the biological treatment of wastewater by converting organic waste into more stable substances. There are three main types of biological wastewater treatment processes - aerobic, anaerobic, and anoxic. Two common biological wastewater treatment methods are trickling filters and activated sludge processes. Trickling filters use microorganisms attached to media to treat wastewater as it trickles down. Activated sludge processes use air and microorganisms in suspension to treat wastewater in aeration tanks, with the treated wastewater then sent to secondary clarifiers. Design considerations for biological wastewater treatment systems include organic loading rates, hydraulic loading rates, and detention
A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions.
In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid.
This process, known as fluidization, imparts many important advantages to the FBR.
As a result, the fluidized bed reactor is now used in many industrial applications
A bioreactor provides an environment for optimal growth and metabolic activity of organisms. It comes in various sizes from small shake flasks to large industrial plants. The conditions inside must be carefully controlled and monitored to support the living microorganisms. Factors like oxygen levels, temperature, pH, and agitation must be maintained. Bioreactor design involves configurations for heat transfer, mixing, mass transfer, and foam removal while ensuring sterility. Common bioreactor types include stirred tank, bubble column, airlift, fluidized bed, and packed bed designs.
Scalability of a Single-use Bioreactor Platform for Biopharmaceutical Manufac...KBI Biopharma
Increasing adoption of single-use technologies for bioprocessing along with higher titers from cell culture bioreactor processes has allowed clinical and even commercial manufacturing to be successfully performed in 2000 L-scale single-use bioreactors. Several biopharmaceutical manufacturers have successfully adopted single-use bioreactors for production. However, information about process scalability from glass bioreactors to 2000 L single-use bioreactors for different types of CHO cell lines is not widely available. Here we provide an overview of the key
differences between single-use and conventional stainless steel bioreactors, and highlight factors that are employed while scaling-up from small-scale glass bioreactors to 2000 L-scale single-use bioreactors. Several case studies focusing on process performance across scales into single-use bioreactors are provided. This analysis confirms that the 2000 L-scale single-use bioreactorsystem can be robustly employed for biopharmaceutical manufacturing.
(1) Bioreactors provide a controlled environment for cultivating microorganisms or cells. They consist of a vessel with mixing, aeration, temperature control and other components.
(2) There are various types of bioreactors including batch, continuous, bubble column, airlift and fluidized bed bioreactors. Batch bioreactors operate in discrete batches while continuous bioreactors allow continuous addition and removal of material.
(3) Batch bioreactors are simpler but have inconsistent productivity while continuous bioreactors are more complex but allow steady state conditions and more efficient resource use ideal for large scale processes.
This document discusses various types of bioreactors used for culturing cells and microorganisms. It begins with an introduction to bioreactors and factors that influence oxygen transfer. It then describes different methods of aeration including standing cultures, shake flasks, stirred tank reactors, bubble column reactors, and fluidized bed reactors. Critical dissolved oxygen levels are discussed for various microorganisms. Factors that can affect oxygen demand and supply in bioreactors are also summarized.
Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale.
The areas of different fields of science like:
Oil Refining
Pharmaceuticals
Biotechnology
Chemical Industries
Sustainable Development
The document discusses centrifuges and centrifugation. It begins by summarizing the early history of centrifuges, including inventions in the 18th and 19th centuries. It then provides definitions and explanations of key terms like centrifuge, centrifugation, and relative centrifugal force. The rest of the document details different types of centrifuges, components of centrifuges, separation techniques, and rotors and tubes used in centrifugation.
The document discusses different types of reactors used in environmental engineering. It begins by describing suspended growth reactors, where cells are suspended, and biofilm reactors, where cells attach to surfaces. The key factors in choosing a reactor type are then outlined. The aims of the chapter are to understand how to construct mass balances and derive equations describing reactor size and performance. Typical reactors like batch, continuous stirred-tank (CSTR), and plug-flow (PFR) are then examined in more detail through examples of their characteristics, kinetics, and mass balance equations.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
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A batch reactor undergoes a controlled chemical reaction within a contained vessel. Reactants are added at the start and nothing is added or removed until the reaction is complete. Semi-batch reactors are similar but allow reactants or products to be continuously added or removed during the reaction. Batch reactors are useful for small scale or specialized productions like pharmaceuticals due to their flexibility, but they have higher operating costs than continuous reactors.
This document discusses different types of bioreactors. It begins by defining a bioreactor as an engineered device that supports a biologically active environment. It then classifies bioreactors as either suspended growth or biofilm reactors. The main types of bioreactors discussed are batch, continuous stirred-tank (CSTR), plug flow, packed bed, fluidized bed, and trickling filters. Applications mentioned include waste water treatment, food production, and reducing air pollutants. The document provides details on the operation and uses of these various bioreactor configurations.
This presentation provides an overview of bubble column reactors. It begins with an introduction that defines a bubble column reactor as a cylindrical vessel with a gas distributor at the bottom used for multiphase contact and reactions. The presentation then covers the theory of bubble column operation, design equations for parameters like superficial gas velocity and gas holdup, applications in chemical processes, and advantages like good heat and mass transfer with low costs and no moving parts.
This document summarizes key aspects of bioreactor design and operation. It describes common bioreactor configurations like stirred tank, bubble column, airlift, fluidized bed, and packed bed reactors. Design features are discussed like ports for sensors and gas sparging. Sterilization methods like steam sterilization in-place and clean-in-place procedures using alkaline and water rinses are outlined. Mass transfer processes and considerations for sterile operation are also briefly covered.
An insight into spray pulsed reactor through mathematical modeling of catalyt...Siluvai Antony Praveen
This document presents a mathematical model developed to study the impact of nozzle-catalyst distance and bulk gas temperature on the conversion and hydrogen evolution rate in a spray pulse reactor for the catalytic dehydrogenation of cyclohexane. The model was able to predict the effects of reactor configuration and operating parameters on conversion and evolution rate with over 90% accuracy. Reactor optimization analysis identified an optimal design of 5 cm nozzle-catalyst distance and 50°C bulk gas temperature, which was predicted to increase conversion from approximately 32% to 74%. The model provides a means to design endothermic heterogeneous catalytic reactions in spray pulse reactors.
The experiment studied the effect of temperature on the saponification reaction of ethyl acetate and sodium hydroxide in a batch reactor. Calibration curves were plotted at different temperatures to determine conductivity and conversion levels. Reactants were added to a jacketed reactor and stirred at 30°C and 50°C, with conductivity readings recorded. The data showed lower temperatures resulted in higher conversions as evidenced by lower conductivity readings. Batch reactors are useful for small-scale testing but have high operating costs and variable product quality compared to continuous reactors.
1) The document summarizes a study on the hydrodynamics of a semi-fluidized bed reactor using internals. Experiments were conducted with varying particle size, bed height, liquid velocity, and internals.
2) The minimum and maximum semi-fluidization velocities increased with larger particle size, higher bed expansion ratio, and use of internals. Pressure drop also rose with these factors.
3) Internals enhanced mixing and accelerated packed bed formation once minimum fluidization occurred, though a higher initial velocity was needed due to restricted particle motion. The study provides insight into optimizing semi-fluidized bed reactor efficiency through internals design.
The document discusses oxygen transfer in aerobic fermentation processes. It states that the majority of fermentation processes require oxygen, which has low solubility in water. For efficient oxygen transfer, dissolved oxygen must be continuously supplied to microorganisms at a rate equal to their demand. Key factors that influence oxygen transfer rate include bubble size, agitation intensity, viscosity, foaming, and vessel geometry. Equations are provided to characterize oxygen transfer rates and model maximum cell densities supported by reactors based on process conditions. Scale-up of fermentation processes requires matching critical environmental parameters like dissolved oxygen levels between small and large scales.
Biological and Advanced Water Treatment.pptxYalelet Abera
Micro-organisms play an essential role in the biological treatment of wastewater by converting organic waste into more stable substances. There are three main types of biological wastewater treatment processes - aerobic, anaerobic, and anoxic. Two common biological wastewater treatment methods are trickling filters and activated sludge processes. Trickling filters use microorganisms attached to media to treat wastewater as it trickles down. Activated sludge processes use air and microorganisms in suspension to treat wastewater in aeration tanks, with the treated wastewater then sent to secondary clarifiers. Design considerations for biological wastewater treatment systems include organic loading rates, hydraulic loading rates, and detention
A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions.
In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid.
This process, known as fluidization, imparts many important advantages to the FBR.
As a result, the fluidized bed reactor is now used in many industrial applications
A bioreactor provides an environment for optimal growth and metabolic activity of organisms. It comes in various sizes from small shake flasks to large industrial plants. The conditions inside must be carefully controlled and monitored to support the living microorganisms. Factors like oxygen levels, temperature, pH, and agitation must be maintained. Bioreactor design involves configurations for heat transfer, mixing, mass transfer, and foam removal while ensuring sterility. Common bioreactor types include stirred tank, bubble column, airlift, fluidized bed, and packed bed designs.
Scalability of a Single-use Bioreactor Platform for Biopharmaceutical Manufac...KBI Biopharma
Increasing adoption of single-use technologies for bioprocessing along with higher titers from cell culture bioreactor processes has allowed clinical and even commercial manufacturing to be successfully performed in 2000 L-scale single-use bioreactors. Several biopharmaceutical manufacturers have successfully adopted single-use bioreactors for production. However, information about process scalability from glass bioreactors to 2000 L single-use bioreactors for different types of CHO cell lines is not widely available. Here we provide an overview of the key
differences between single-use and conventional stainless steel bioreactors, and highlight factors that are employed while scaling-up from small-scale glass bioreactors to 2000 L-scale single-use bioreactors. Several case studies focusing on process performance across scales into single-use bioreactors are provided. This analysis confirms that the 2000 L-scale single-use bioreactorsystem can be robustly employed for biopharmaceutical manufacturing.
(1) Bioreactors provide a controlled environment for cultivating microorganisms or cells. They consist of a vessel with mixing, aeration, temperature control and other components.
(2) There are various types of bioreactors including batch, continuous, bubble column, airlift and fluidized bed bioreactors. Batch bioreactors operate in discrete batches while continuous bioreactors allow continuous addition and removal of material.
(3) Batch bioreactors are simpler but have inconsistent productivity while continuous bioreactors are more complex but allow steady state conditions and more efficient resource use ideal for large scale processes.
This document discusses various types of bioreactors used for culturing cells and microorganisms. It begins with an introduction to bioreactors and factors that influence oxygen transfer. It then describes different methods of aeration including standing cultures, shake flasks, stirred tank reactors, bubble column reactors, and fluidized bed reactors. Critical dissolved oxygen levels are discussed for various microorganisms. Factors that can affect oxygen demand and supply in bioreactors are also summarized.
Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale.
The areas of different fields of science like:
Oil Refining
Pharmaceuticals
Biotechnology
Chemical Industries
Sustainable Development
The document discusses centrifuges and centrifugation. It begins by summarizing the early history of centrifuges, including inventions in the 18th and 19th centuries. It then provides definitions and explanations of key terms like centrifuge, centrifugation, and relative centrifugal force. The rest of the document details different types of centrifuges, components of centrifuges, separation techniques, and rotors and tubes used in centrifugation.
The document discusses different types of reactors used in environmental engineering. It begins by describing suspended growth reactors, where cells are suspended, and biofilm reactors, where cells attach to surfaces. The key factors in choosing a reactor type are then outlined. The aims of the chapter are to understand how to construct mass balances and derive equations describing reactor size and performance. Typical reactors like batch, continuous stirred-tank (CSTR), and plug-flow (PFR) are then examined in more detail through examples of their characteristics, kinetics, and mass balance equations.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
This presentation was provided by Racquel Jemison, Ph.D., Christina MacLaughlin, Ph.D., and Paulomi Majumder. Ph.D., all of the American Chemical Society, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
2. 2
Introduction
Several important chemical engineering concepts in
Bioprocess Engineering are transport phenomena (fluid flow,
mixing, heat and mass transfer), unit operations, reaction
engineering, and bioreactor engineering.
Fluid flow, mixing, and reactor engineering are skipped in this
class. They are available more detail in several chemical
engineering books.
We start with the heat transfer in bioreactors
3. 3
Two types of common heat transfer application
in bioreactor operation
• In situ batch sterilization of liquid medium. In this process,
the fermenter vessel containing medium is heated using
steam and held at the sterilization temperature for a period
of time; cooling water is then used to bring the temperature
back to normal operating conditions
• Temperature control during reactor operation. Metabolic
activity of cells generates heat. Some microorganisms need
extreme temperature conditions (e.g. psycrophilic,
thermophilic microorganisms)
Heat transfer configurations for bioreactors: jacketed vessel,
external coil, internal helical coil, internal baffle-type coil,
and external heat exchanger.
4. 4
Pro’s and cons of the heat exchanger configurations
• External jacket and coil give low heat transfer area. Thus, they are
rarely used for industrial scale.
• Internal coils are frequently used in production vessel; the coils can be
operated with liquid velocity and give relatively large heat transfer
area. But the coil interfere with the mixing in the vessel and make
cleaning of the reactor difficult. Another problem is film growth of
cells on the heat transfer surface.
• External heat exchanger unit is independent of the reactor, easy to
scale up, and provide best heat transfer capability. However, conditions
of sterility must be met, the cells must be able to withstand the shear
forces imposed during pumping, and in aerobic fermentation, the
residence time in the heat exchanger must be small enough to ensure
the medium does not become depleted of oxygen.
5. 5
Heat exchangers in fermentation processes
• Double-pipe heat exchanger
• Shell and tube heat exchanger
• Plate heat exchanger
• Spiral heat exchanger
In bioprocess, the temperature difference is relatively small.
Thus, plate heat exchanger is almost never being used
The concepts and calculation for heat exchangers and their
configurations are available in the text book ( Pauline Doran,
Bioprocess Eng Principle, chapter 8)
7. 7
Introduction
The Fick’s law of diffusion
Role of diffusion in Bioprocess
• Scale of mixing
Mixing on a molecular scale relies on diffusion as the final step in mixing
process because of the smallest eddy size
• Solid-phase reaction
The only mechanism for intra particle mass transfer is molecular diffusion
• Mass transfer across a phase boundary
Oxygen transfer to gas bubble to fermentation broth, penicillin recovery
from aqueous to organic liquid, glucose transfer liquid medium into mould
pellets are typical example.
dy
dC
D
J A
AB
A
8. 8
Film theory
The two film theory is a useful model for mass transfer
between phase. Mass transfer of solute from one phase to
another involves transport from bulk of one phase to the
interface, and then from the interface to the bulk of the second
phase. This theory is based on idea that a fluid film or mass
transfer boundary layer forms whenever there is contact
between two phases. According to film theory, mass transfer
through the film is solely by molecular diffusion and is the
major resistance.
CA1i CA1 Bulk fluid 1
Bulk fluid 2 CA2i
CA2 Film 2 Film 1
9. 9
Convective mass transfer
AGi
AG
G
AG
AL
ALi
L
AL
C
C
a
k
N
C
C
a
k
N
It refers to mass transfer occurring in the presence of bulk
fluid motion
k: mass transfer coefficient [m/s]
a: area available for mass transfer [m2/m3]
CAo: concentration of A at bulk fluid
CAi: concentration of A at interface
For gas-liquid system, A from gas to liquid:
Ai
Ao
A C
C
ka
N
10. 10
Overall mass transfer coefficient
Refers to the book Geankoplis (2003), Transport Processes and
Separation Process Principles, 4th ed, chapter 10.4.
Oxygen transport to fermentation broth can be modeled as
diffusion of A through stagnant or non-diffusing B.
If A is poorly soluble in the liquid, e.g. oxygen in aqueous
solution, the liquid-phase mass transfer resistance dominates
and kGa is much larger than kLa. Hence, KLa ≈ kLa.
AL
AL
L
A
L
G
G
C
C
a
K
N
a
k
m
a
k
a
K
*
'
1
1
11. 11
Oxygen transfer from gas bubble to cell
Eight steps involved:
i. Transfer from the interior of the bubble to the gas-liquid interface
ii. Movement across the gas-liquid interface
iii. Diffusion through the relatively stagnant liquid film surrounding the
bubble
iv. Transport through the bulk liquid
v. Diffusion through the relatively stagnant liquid film surrounding the
cells
vi. Movement across the liquid-cell interface
vii. If the cells are in floc, clump or solid particle, diffusion through the
solid of the individual cell
viii. Transport through the cytoplasm to the site of reaction.
12. 12
Analyzes for most bioreactors in each step involved
i. Transfer through the bulk phase in the bubble is relatively fast
ii. The gas-liquid interface itself contributes negligible resistance
iii. The liquid film around the bubble is a major resistance to oxygen
transfer
iv. In a well mixed fermenter, concentration gradients in the bulk liquid
are minimized and mass transfer resistance in this region is small,
except for viscous liquid.
v. The size of single cell <<< gas bubble, thus the liquid film around
cell is thinner than that around the bubble. The mass transfer
resistance is negligible, except the cells form large clumps.
vi. Resistance at the cell-liquid interface is generally neglected
vii. The mass transfer resistance is small, except the cells form large
clumps or flocs.
viii. Intracellular oxygen transfer resistance is negligible because of the
small distance involved
14. 14
Downstream processing, what and why
Downstream processing is any treatment of culture broth after fermentation
to concentrate and purify products. It follows a general sequence of steps:
1.Cell removal (filtration, centrifugation)
2.Primary isolation to remove components with properties significantly
different from those of the products (adsorption, liquid extraction,
precipitation). Large volume, relatively non selective
3.Purification. Highly selective (chromatography, ultra filtration, fractional
precipitation)
4.Final isolation (crystallization, followed by centrifugation or filtration
and drying). Typical for high-quality products such as pharmaceuticals.
Downstream processing mostly contributes 40-90 % of total cost.
15. 15
Filtration
Type of filtration unit:
• Plate and frame filter. For small fermentation batches
• Rotary-drum vacuum filter. Continuous filtration that is widely used in the
fermentation industry. A horizontal drum 0.5-3 m in diameter is covered
with filter cloth and rotated slowly at 0.1-2 rpm.
The filtration theory and equation are not explained here since they are
available in the course “Unit Operations of Chemical Engineering I”.
16. 16
Centrifugation
Centrifugation is used to separate materials of different density when a
force greater than gravity is desired
The type of industrial centrifugation unit:
• Tubular bowl centrifuge (Narrow tubular bowl centrifuge or
ultracentrifuge, decanter centrifuge, etc). Simple and widely applied in food
and pharmaceutical industry. Operates at 13000-16000 G, 105-106 G for
ultracentrifuge
• Disc-stack bowl centrifuge. This type is common in bioprocess. The
developed forces is 5000-15000 G with minimal density difference between
solid and liquid is 0.01-0.03 kg/m3. The minimum particle diameter is 5 µm
18. 18
The centrifugation theory
g
D
u p
f
p
g
2
18
The terminal velocity during gravity settling of a small spherical particle in
dilute suspension is given by Stoke’s law:
Where ug is sedimentation velocity under gravity, ρp is particle density, ρf
is liquid density, µ is liquid viscosity, Dp is diameter of the particle, and g
is gravitational acceleration.
In the centrifuge:
uc is particle velocity in the centrifuge, ω is angular velocity in rad/s, and r
is radius of the centrifuge drum.
r
D
u p
f
p
c
2
2
18
19. 19
The centrifugation theory
g
r
Z
2
g
u
Q
2
The ratio of velocity in the centrifuge to velocity under gravity is called the
centrifuge effect or G-number.
Industrial Z factors: 300-16 000, small laboratory centrifuge may up to 500 000.
The parameter for centrifuge performance is called Sigma factor
Q is volumetric feed rate. The Sigma factor explain cross sectional area of a gravity
settler with the same sedimentation characteristics as the centrifuge. If two
centrifuge perform with equal effectiveness
2
2
1
1
Q
Q
20. 20
The centrifugation theory
3
1
3
2
2
tan
3
1
2
r
r
g
N
Disc-stack bowl centrifuge
N is number of disc, θ is half-cone angle of the disc.
The r1 and r2 are inner and outer radius of the disc, respectively.
Tubular-bowl centrifuge
2
1
2
2
2
3
2
r
r
g
b
b is length of the bowl, r1 and r2 are inner and outer radius of the wall of the
bowl.
21. 21
Cell disruption
Mechanical cell disruption methods
•French press (pressure cell) and high-pressure homogenizers. In these
devices, the cell suspension is drawn through a check valve into a pump
cylinder. At this point, it is forced under pressure (up to 1500 bar) through a
very narrow annulus or discharge valve, over which the pressure drops to
atmospheric. Cell disruption is primary achieved by high liquid shear in the
orifice and the sudden pressure drop upon discharge causes explosion of the
cells.
•Ultrasonic disruption. It is performed by ultrasonic vibrators that produce a
high-frequency sound with a wave density of approximately 20 kHz/s. A
transducer convert the waves into mechanical oscillations via a titanium
probe immersed in the concentrated cell suspension. For small scale
23. 23
The equation for Manton-Gaulin homogenizer
kNp
R
R
R
m
m
ln
Rm: maximum amount protein available for release
R: amount of protein release after N passes through the
homogenizer
k: temperature-dependent rate constant
p: operating pressure drop
: resistance parameter of the cells, for S. cerevisiae is 2.9
24. 24
Cell disruption
Non mechanical cell disruption methods
Autolysis, use microbe own enzyme for cell disruption
Osmotic shock. Equilibrating the cells in 20% w/v buffered sucrose, then
rapidly harvesting and resuspending in water at 4oC.
Addition of chemicals (EDTA, Triton X-100), enzymes (hydrolyses, b-
glucanases), antibiotics (penicillin, cycloserine)
25. 25
Chromatography
Chromatographic techniques usually employed for high value products.
These methods, normally involving columns of chromatographic media
(stationary phase), are used for desalting, concentration and purification
of protein preparations. Several important aspects are molecular weight,
isoelectric point, hydrophobicity and biological affinity. The methods are:
1.Adsorption chromatography
2.Affinity chromatography
3.Gel filtration chromatography
4.High performance liquid chromatography
5.Hydrophobic chromatography
6.Metal chelate chromatography
26. 26
Finishing steps (final isolation)
Crystallization
Product crystallization may be achieved by evaporation, low-temperature
treatment or the addition of a chemical reactive with the solute. The product’s
solubility can be reduced by adding solvents, salts, polymers, and
polyelectrolytes, or by altering pH.
Drying
Drying involves the transfer of heat to the wet material and removal of the
moisture as water vapor. Usually, this must be performed in such a way as to
retain the biological activity of the product. The equipment could be rotary
drum drier, vacuum tray drier, or freeze-drier.
28. 28
Bioreactor configurations
Stirred tank bioreactor
Similar to CSTR; this requires a relatively high input of energy per unit
volume. Baffles are used to reduce vortexing. A wide variety of impeller sizes
and shapes is available to produce different flow patterns inside the vessel; in
tall fermenters, installation of multiple impellers improves mixing.
Typically, only 70-80 % of the volume of stirred reactors is filled with liquid;
this allows adequate headspace for disengagement of droplets from exhaust
gas and to accommodate any foam which may develop. Foam breaker may be
necessary if foaming is a problem. It is preferred than chemical antifoam
because the chemicals reduce the rate of oxygen transfer.
The aspect ratio (H/D) of stirred vessels vary over a wide range. When
aeration is required, the aspect ratio is usually increased. This provides for
longer contact times between the rising bubbles and liquid and produces a
greater hydrostatic pressure at the bottom of the vessel.
Care is required with particular catalysts or cells which may be damaged or
destroyed by the impeller at high speeds.
30. 30
Bioreactor configurations
Bubble column
In bubble-column reactors, aeration and mixing are achieved by gas sparging;
this requires less energy than mechanical stirring. Bubble columns are applied
industrially for production of bakers’ yeast, beer and vinegar, and for
treatment of wastewater.
A height-to-diameter ration of 3:1 is common in bakers’ yeast production; for
other applications, towers with H/D of 6:1 have been used. The advantages
are low capital cost, lack of moving parts, and satisfactory heat and mass
transfer performance. Foaming can be problem.
Homogeneous flow: all bubbles rise with the same upward velocity and there
is no back-mixing of the gas phase.
Heterogeneous flow: At higher gas velocity. Bubbles and liquid tend to rise up
in the center of the column while a corresponding down flow of liquid occurs
near the walls.
31. 31
Bioreactor configurations
Airlift reactor
Airlift reactors are often chosen for culture of plant and animal cells and
immobilized catalyst because shear level are low. Gas is sparged into only part
of the vessel cross section called the riser. Gas hold-up and decreased liquid
fluid density cause liquid in the riser to move upwards. Gas disengages at the
top of the vessel leaving heavier bubble-free liquid to recirculate through the
downcomer. Airlift reactors configurations are internal-loop vessels and
external-loop vessels. In the internal-loop vessels, the riser and downcomer
are separated by an internal baffle or draft tube. Air may be sparged into either
the draft tube or the annulus. In the external-loop vessels, separated vertical
tubes are connected by short horizontal section at the top and bottom. Because
the riser and downcomer are further apart in external-loop vessels, gas
disengagement is more effective than in internal-loop devices. Fewer bubbles
are carried into the downcomer, the density difference between fluids in the
riser and downcomer is greater, and circulation of liquid in the vessel is faster.
Accordingly, mixing is usually better in external-loop than internal-loop
reactors.
33. 33
Stirred and air-driven reactors: comparison of
operating characteristic
For low-viscosity fluids, adequate mixing and mass transfer can be achieved in
stirred tanks, bubble columns and airlift vessels. When a large fermenter (50-
500 m3) is required for low-viscosity culture, a bubble column is an attractive
choice because it is simple and cheap to install and operate. Mechanical-
agitated reactors are impractical at volumes greater than about 500 m3 as the
power required to achieve adequate mixing becomes extremely high.
Stirred reactor is chosen for high-viscosity culture. Nevertheless, mass transfer
rates decline sharply in stirred vessels at viscosities > 50-100 cP.
Mechanical-agitation generates much more heat than sparging of compressed
gas. When the heat of reaction is high, such as in production of single cells
protein from methanol, removal of frictional stirrer heat can be problem so that
air-driven reactors may be preferred.
Stirred-tank and air-driven vessels account for the vast majority of bioreactor
configurations used for aerobic culture. However, other reactor configurations
may be used in particular processes
34. 34
Other bioreactors
Packed bed
Used with immobilized or particulate biocatalysts, for example during the
production of aspartate and fumarate, conversion of penicillin to 6-
aminopenicillanic acid, and resolution of amino acid isomers. Damaged due
to particle attrition is minimal in packed beds compared with stirred reactors.
Mass transfer between the liquid medium and solid catalyst is facilitated at
high liquid flow rate through the bed. To achieve this, packed are often
operated with liquid recycle. The catalyst is prevented from leaving the
columns by screens at the liquid exit. Aeration is generally accomplished in a
separated vessel because if air is sparged directly into the bed, bubble
coalescence produces gas pockets and flow channeling or misdistribution.
Packed beds are unsuitable for processes which produce large quantities of
carbon dioxide or other gases which can become trapped in the packing.
35. 35
Other bioreactors
Fluidized bed
To overcome the disadvantages of packed bed, fluidized bed may be preferred.
Because particles are in constant motion, channeling and clogging of the bed
are avoided and air can be introduced directly into the column. Fluidized bed
reactors are used in waste water treatment with sand or similar material
supporting mixed microbial populations, and with flocculating organisms in
brewing and production of vinegar.
Trickle bed
Is another variation of the packed bed. Liquid is sprayed onto top of the
packing and trickles down through the bed in small rivulets. Air may be
introduced at the base; because the liquid phase is not continuous throughout
the column, air and other gases move with relative ease around the packing.
Trickle-bed reactors are used widely for aerobic wastewater treatment.