Bioreactor.pdf

 Bioreactor.pdf

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Aishwarya

April 24, 2013
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Transcript

  1. Presented by: Aishwarya Singh Gangwar

  2. Outline:  Definition  Types of Bioreactor  Products of

    Bioreactor  Components of Bioreactor  Configurations  Operation modes  Summary
  3. What is a bioreactor?  Bioreactor:Bioreactor can be described as

    a vessel which has provision of cell cultivation under sterile condition & control of environmental conditions e.g., pH, Temp., Dissolved oxygen etc.  Fermenter: Fermenter is a type of bioreactor in which the biocatalyst is a living cell. / A fermenter is a system that provides an anaerobic process for producing alcohol from sugar.
  4. Bioreactor Process Flow: Product Bioreactor Recycle Product separation & purification

    Nutrients tank Waste Input Pre-filtration
  5. Types of bioreactors:  Batch: Media and cells are added

    to the reactor and it is run until a predetermined set point (i.e. time, concentration). The bioreactor has a constant volume (the initial volume).  Fed-Batch: The bioreactor is a batch process in the beginning and after a certain point a feed input is introduced and the volume of the vessel increases.  Continuous: The bioreactor starts with an initial volume and media is constantly introduced and product is constantly taken out. The inputs and outputs are at the same rate, so the volume always remains the same.
  6. Products of bioreactor: Bioreactor products are formed by three basic

    processes: 1. Processes in which the product is produced by the cells is either extracellular or intracellular. 2. Processes that produce a cell mass. 3. Processes that modify a compound that is added to the fermentation process are referred to as ‘biotransformation’.
  7. Components of Bioreactors:

  8. Bioreactors consist of:  Vessel  Agitator  Sparger 

    Baffles  Probes  Temperature  Dissolved Oxygen  pH  Pressure Gauge  Cooling Jacket  Ports for input and output of material  Condenser  Back Pressure Valve  Inlet Filters and Exhaust Filters  Valves  Load Cell
  9. Bioreactor-Vessel  The bioreactor vessel is a container which holds

    the media and the cells  Vessels can be made of glass, stainless steel, or a durable plastic.  All the additional parts of a bioreactor connect to the vessel.  The top of the vessel is called a head plate. On glass reactors, most additional parts are located on the head plate.
  10. Head plate Vessel

  11. Bioreactor-Agitators  Impellers come in many different shapes and sizes

    depending on what type of mixing is needed.
  12. Bioreactors-Sparger  The sparger is an apparatus used to introduce

    gasses into the vessel.  Spargers are located at the bottom of the vessel and consist of a tube with tiny holes for the gas to escape through into the culture.  The gas coming out of the sparger helps to aerate and mix the contents in the vessel, as well as supply oxygen to the cells.
  13.  Ring Sparger  Micro Sparger  Openings on Ring

    Sparger
  14. Bioreactor Baffles  Baffles are obstructions on the side of

    the vessel that generate turbulence in the flow of the culture.  Baffles help to mix the culture by creating a more turbulent flow. Baffles obstruct the flow in the vessel to help mix the contents.
  15. Bioreactor Probes  Bioreactors require probes to monitor the culture

    in the vessel.  The probes are found at different locations on the vessel: head plate, top probe belt, bottom probe belt.  Useful probes include temperature, pH, DO (dissolved oxygen), and CO2
  16. Bioreactor-Cooling Jacket  Cells give off heat when growing and

    dividing. To maintain a constant temperature in the reactor, the vessel is covered by a cooling jacket.  Coolant (cold water or glycol) flows through the cooling jacket to regulate the temperature.  The temperature is controlled by the flow rate of the coolant.
  17. Stainless Steel Cooling Jacket surrounds the vessel.

  18. Bioreactor-Ports  Bioreactors require addition ports, where material is either

    introduced or removed from the vessel.  Ports are needed to add the media (media port), cells (inoculation port), and nutrients (feed ports).  Ports are also used for the addition of acid and base for pH control.  A sample port is also located on each vessel to remove culture for off-line investigation.
  19. Ports

  20. Bioreactor-Condenser  A condenser is an apparatus that captures saturated

    air leaving the vessel.  The condenser is cooler than the saturated air allowing it to condense on the surface and return to the vessel as a liquid.
  21. Bioreactor-Filters  Bioreactors need inlet filters to ensure the gasses

    entering the vessel are sterile.  They require exhaust filters to keep the reactor sterile and allow gas to escape to regulate pressure.  Filters require a filter housing – a stainless steel cabinet to hold and sterilize the filter.
  22. Bioreactor-Back pressure valve  A bioreactor must remain under constant

    pressure. • Constant pressure helps to ensure sterility of the reactor by keeping microbes out.  The pressure is regulated using a back pressure valve.
  23. Bioreactor-Valves  Valves are used to control the flow of

    either gas or liquid.  Manual Valves – open and close the valves with your hand.  Pneumatic Valves – automatic valve which opens and closes with the use of high pressured air (instrument air).  Steam Lock Valves- a two valve assembly so you can Allow a fluid to flow through a portion of the valve and then close and use the other portion of the valve.
  24. Bioreactor-Load cell  A load cell is a scale that

    measures the weight of the bioreactor.  The weight of the bioreactor can be correlated to the volume of liquid in the vessel by using the density of the cell culture medium. Weight = Density × Volume
  25. Bioreactor Configurations

  26. 1. Stirred tank Mixing method: Mechanical agitation • Baffles are

    usually used to reduce vortexing • Applications: free and immobilized enzyme reactions • High shear forces may damage cells • Require high energy input
  27. 2. Bubble Column  Mixing method: Gas Sparging • Simple

    design • Good heat and mass transfer • Low energy input  Gas-liquid mass transfer coefficients depend largely on bubble diameter and gas hold-up.
  28. 3. Airlift Reactor  Mixing method: airlift • Compared to

    bubble column reactors, in an airlift reactors, there are two liquid steams: up- flowing and down- flowing steams. • Liquid circulates in an airlift reactor as a resutl of density difference between riser and downcomer.
  29. 4. Packed-bed Reactor  Packed-bed reactors are used with immobilized

    or particulate biocatalysts.  Medium can be fed either at the top or bottom and forms a continuous liquid phase.
  30. 5. Trickle-bed Reactor  The trickle-bed reactor is another variation

    of the packed bed reactors.  Liquid is sprayed onto the top of the packing and trickles down through the bed in small rivulets.
  31. 6. Fludized bed Reactor  When the packed beds are

    operated in up flow mode, the bed expands at high liquid flow rates due to upward motion of the particles.
  32. Bioreactor Operations Modes

  33. 1. Batch Operation  A foam breaker may be installed

    to disperse foam. A batch bioreactor is normally equipped with an agitator to mix the reactant, and the pH of the reactant is maintained by employing either buffer solution or a pH controller Batch operation with stirring S m S s C K C dt dC    max     t C C C C K s s s s m max 0 0 ln     Change of Cs with time, t
  34. 2. Plug-flow Mode In a plug-flow reactor, the substrate enters

    one end of a cylindrical tube. It is packed with immobilized enzyme and the product steam leaves at the other end. Continuous operation without stirring Residence time An ideal plug-flow reactor can approximate the long tube, packed-bed and hollow fiber or multistage reactor   t C C C C K s s s s m max 0 0 ln     F V   F, Cs0 F, Cs t = 0 V
  35. 3. Continuous Stirred-tank F, Cs0 Continuous operation with stirring F,

    Cs V A continuous stirred- tank reactor (CSTR) is an ideal reactor which is based on the assumption that the reactants are well mixed.
  36. Stirred-tank reactor cont… V Mass balance of substrate: dt dC

    V V FC FC s s s s     0 on Accumulati n Consumptio Output - Input   0  dt dC s S m S C K C   max   0 max 0     s m s s s C K C V FC FC  Steady state: Michaelis-Menten rate: F, Cs0 F, Cs
  37. F, Cs0 s s s m s C C C

    K C     0 max   F, Cs V Mass balance of substrate: 0 max 0     s m s s s C K C V FC FC     s m s s s C K C C C V F    0 max   1  V F
  38. Summary:  Bioreactors will be integral to the development of

    many new high value products and the replacement of existing chemical-based commodity processes.  The proper selection and design of the bioreactor will determine the optimal commercial bioprocess and the corresponding capital investment.  The bioreactor should not be regarded as an isolated unit, but as part of an integrated unit operation with both upstream (preparation) and downstream (separations) unit operations.
  39. None