Conventional bioreactor and their components

1. Conventional Bioreactor:
 By
 Aswartha Harinath Reddy
 Department of Biotechnology
 Christ University

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4. Structure of Conventional bioreactors :
Factors considered for designing a bioreactor.
 Conventional bioreactors are cylindrical vessels with domed top
and bottom.
 The reaction vessel, surrounded by a cooling jacket and provided
with a sparger at the bottom.
 The air (or other gases such as CO2and NH3 ) can be introduced
through the sparger.

5.  The agitator shaft is connected to a motor at the bottom.
 The reaction vessel has side ports for pH, temperature and
dissolved O2 sensors.
 Above the liquid level of the reaction vessel, connections for acid,
alkali, antifoam chemicals and inoculum are located.

6.  The bioreactor vessel is usually made up of stainless steel.
 The materials used for the construction of bioreactor must be
non-toxic and must withstand the repeated sterilization with
high pressure steam.
 The bioreactor is usually designed to work at higher temperature
(150-180°C), higher pressure.

7. Aspect ratio:
 The aspect ratio of bioreactor describes the proportional
relationship between height and width (Diameter).
 The size of the bioreactor i.e height and width of bioreactor
referred as Aspect ratio.
 The aspect ratio of stirred tank bioreactor is 3:5.

8. Components of the fermenters:

9. Impellers or Agitators:
 This facilitates the mixing of the contents of the reactor which
keeps the “cells” in the perfect homogenous condition.
 It provide transport of nutrients and oxygen to cells to produce the
desired products.

10. Speed of Impellers:
 The speed of the impellers determines the stirring rate in a
fermenter.
 The maximum speed of the impellers is around 60-120 rpm in 450
liters fermenter.

11. Types of Impellers:
 Propellers:
 Turbines:
 Paddles:

12. Propellers:
 The marine propeller is a relatively
small and high speed impellers.
 Widely used in low viscosity
liquid systems.
 Speed of rotation will vary from
400 rpm to 1000 rpm.
It has a high rate of flow displacement and
generates strong currents in an axial direction.

13. Turbines:
 A flat blade turbine (FBT) impeller is widely used in many
submerged microbial reactions.
 A turbine consists of several straight blades mounted vertically
on a flat plate.
 Turbines are moderate speed impellers and fluid flow is generated
in a radial and tangential directions.

14. Paddles:
 In Paddle impellers straight blades mounted vertically on a long,
horizontal shaft.
 These impellers run at a slow to moderate speed (2 to 150 rpm).
 Used to mix high viscosity liquids.
 Radial and tangential currents are generated during rotation of
paddles.

15. Aeration:
 The bioreactor gets aerated by the supply of O2.
 Aeration performed by bubbling air through spargers.
 A sparger is a tool used for introducing air into the fermentation
medium.

16. Three basic types of sparger:
 1. The porous sparger,
 2. The orifice sparger (a perforated pipe)
 3. The nozzle sparger (an open or partially closed pipe).

17. Porous Sparger:
 The porous sparger is mainly used for laboratory scale non
agitated fermenter.
 It is made up of glass, ceramics or metal.

18. Orifice Sparger :
 Used in small stirred fermenters.
 The perforated pipes were arranged below the impeller in the
form of rings (ring sparger).


19. Nozzle Sparger:
 Nozzle spargers used in laboratory to industrial scale bioreactors.
 Nozzle spargers have a single open or partially closed pipe.
 Ideally the pipe should be positioned centrally below the impeller.
 The single-nozzle sparger normally does not get blocked.

20. Temperature regulation
 There are two temperature ranges to run the fermentations a
mesophilic range (20-45°C) and a thermophilic range (> 45°C).

21. Cooling Jacket :
 The jacket provides the annular area for circulation of constant
temperature water.
 Which keeps the temperature of the bioreactor at a constant
value.
 Desired temperature water is constantly circulated in to jacket
to maintain a particular temperature in the bioreactor.

22. pH monitoring
 The electrodes or pH probes used to monitor pH of
bioreactors.
 The electrodes or pH probes withstand high TMP and
Pressure.
 Combination of electrodes reference and glass electrodes are
used.

25. Antifoaming agents.
 A an anti-foaming agent is a chemical additive that reduces the
formation of foam in industrial process liquids.
 A foam is formed by trapping pockets of gas in a liquid or
solid.

26.  Vegetable & Animal Oil
 Castor Oil
 Silicones Oil

27.  Agitation and aeration is one of the reason for the formation of
foam.
 During anaerobic fermentation of sugar produce CO2 is the
end product.

30. Cleaning of Bioreactor:
 As the fermentation is complete, the bioreactor is harvested i.e. the
contents are removed for processing.
 The bioreactor is then prepared for the next round of
fermentation after cleaning (technically called turn round).
 The time taken for turn round referred to as down time should
be as short as possible (since it is non-productive).

35. Thank you………………