The document discusses different types of bioreactors used in fermentation technology. It describes continuous stirred tank reactors, bubble column bioreactors, airlift bioreactors, fluidized bed bioreactors, packed bed bioreactors, photo-bioreactors, tower bioreactors, and rotary drum reactors. For each type of bioreactor, it provides details on the design, functioning, applications and advantages. Continuous stirred tank reactors provide good mixing but are open systems, while bubble column and airlift bioreactors rely on the bubbling of gas to promote mixing and circulation of the medium.

1. Bioreactors-:
 By
 Harinatha Reddy A
 Department of Biotechnology
 Christ University

2. Introduction:
 The heart of fermentation technology is the fermenter.
 Bioreactor is a device in which the organisms are cultivated and
motivated to form the desired product.

3. A bioreactor should provide:
 Agitation (for mixing of cells and medium).
 Aeration (aerobic fermentors); for O2 supply.
 Regulation of factors: like TMP, pH, pressure, nutrient feeding.
 Provide aseptic environment.

4. Types of Bioreactors:
 Based on design and function the bio reactors, there are different
types of bioreactors.
 Continuous stirred tank reactors,
 Airlift bioreactors,
 Bubble colum bioreactors,
 Fluidized bed bioreactors,
 Packed bed bioreactors,
 Tower reactors,
 Drum reactors,
 Photobioreactors.

5. 1. Continuous stirred tank reactors (CSTRs):
• CSTRs are open or closed systems , the contents of the
fermenters are well mixed by agitators and remove
continuously form fermenter.

6. Continuous stirred tank reactors CSTRs :
 A continuous stirred tank bioreactor
consists of a cylindrical vessel (Made up
of steel).
 CSTRs contain central shaft attached to
motor that supports one or more
agitators (impellers).
 The shaft is fitted at the bottom of the
bioreactor.
 The number of impellers is variable and
depends on the size of the bioreactor.

7.  In CSTRs the air is added to the culture medium through a
device called sparger.
 The spargers and impellers (agitators) provide better gas
distribution system throughout the vessel.

8. Applications:
 CSTRs are usually applied in waste water treatment processes.
 CSTRs used for maintenance of animal cell cultures.
 CSTRs provide good mixing of the contents.
 CSTRs provide high dilution rate.

9. 2. Bubble Column Bioreactors:
 A continuous stirred tank
bioreactor consists of a
cylindrical vessel (Made up of
steel).
 In the bubble column bioreactor,
the air or gas is introduced at
the base of the column through
pipes or plates, or metal micro
spargers

10. Applications:
 Bubble column reactors are used in various types of chemical
reactions like oxidation reactions.
 For the cultivation of algae bioreactor.

11. 3. Airlift Bioreactors:
 The internal circulation and mixing of
medium are achieved by bubbling air.
 In the airlift bioreactors, the medium of the
vessel is divided into two interconnected
zones by means of a baffle or draft tube.
 Inner gassed region ( Riser) here gas is
pumped.
 Outer un-gassed region ( Down comer)

12. There are two types of airlift bioreactors:
 Internal-loop airlift bioreactor.
 External loop airlift bioreactor.

13. Internal-loop airlift bioreactor.
 Internal-loop airlift bioreactor has a single
container with a central draft tube.
 The air is pumped form the bottom of the central
draft tube that creates interior liquid circulation
channels.
 These bioreactors are simple in design, and
provide circulation at a fixed rate for
fermentation.

14. External loop airlift bioreactor:
 External loop airlift bioreactor possesses an
external loop so that the liquid circulates
through separate independent channels.
 In general, the airlift bioreactors are more
efficient than bubble columns, particularly for
more denser suspensions of microorganisms.
 This is mainly because in these bioreactors, the
mixing of the contents is better compared to
bubble columns.

15. Applications:
 Airlift bioreactors are commonly employed for aerobic
bioprocessing technology.
 Airlift bioreactors used for methanol production, waste water
treatment, single-cell protein production.

16. Fluidized Bed Bioreactors:

17. Fluidized Bed Bioreactors:

18.  Fluidized bed bioreactor is comparable to bubble column
bioreactor.
 The top of the bioreactor is expanded and consists of narrow bottom
to reduce the velocity of the fluid.

19.  In fluidized bioreactors solids (Immobilized enzymes or
microorganism) are retained in the reactor while the liquid
flows out.
 In this bioreactors immobilized enzymes, immobilized
microorganisms are used.

20.  For an efficient operation of fluidized beds, gas is spared to create
a suitable gas-liquid-solid fluid bed.
 The suspended solid particles (density) are not too light or high
other wise they may float way along with fermented culture.

21. Advantages:
 Uniform Particle Mixing.
 Ability to Operate Reactor in Continuous State.
 Commonly used in Wastewater treatment.
 Petroleum processing.

22. Packed Bed Bioreactors:

23.  A bed of solid particles, with biocatalysts packed in a column
constitutes a packed bed bioreactor.
 The solids used may be porous or non-porous gels.
 A nutrient broth flows continuously over the immobilised
biocatalyst.

24.  The products obtained in the packed bed bioreactor are released
into the fluid and removed.
 While the flow of the fluid can be downward, down flow under
gravity is preferred.

25. Advantage:
 The packed bed bioreactors do not allow accumulation of the end
products to any significant extent.
Disadvantage:
 Because of poor mixing of nutrients throughout the fermenter.
 It is rather difficult to control the pH of packed bed bioreactors
by the addition of acid or alkali.

26. Applications:
 Anaerobic packed-bed bioreactor for the production of hydrogen
and organic acids.
 Packed-bed bioreactors for mammalian cell culture.
 Enzymatic conversion of penicillin to 6-amino penicillanic acid.

27. Photo-Bioreactors:
Centrifugal pumps or airlift pumps.

28.  These are the bioreactors specialised for fermentation that can be
carried out either by exposing to sunlight or artificial illumination.
 The outdoor photo-bioreactors are preferred.
 Certain important compounds are produced by employing photo-
bioreactors e.g., carotenes and xanthophyll's.

29.  They are made up of glass or more commonly transparent plastic.
 The array of glass tubes or flat panels constitute light receiving
systems (solar receivers).
 The culture and nutrients and medium can be circulated through
the glass tubes or solar receivers by methods such as using
centrifugal pumps or airlift pumps.

30.  Photo-bioreactors are usually operated in a continuous mode at
a temperature in the range of 25-40°C.
 Microalgae and cyanobacteria are normally used.
 The organisms grow during day light while the products are
produced during night.

31. Tower Bioreactors:

32. Tower Bioreactors:

33.  Tower fermenters are modified stirred tank reactors that do not
require agitation.
 Therefore, they lack shafts, motor, impellers (Agitators) and blades.
 But it contain spargers to pump air in to bioreactor.


34.  They consist of a long cylindrical vessel with an inlet at the
bottom, an exhaust nutrients at the top, and a jacket to control
temperature.

35. Applications:
 The tower fermenters easy to construct.
 Tower fermenters have found applications in continuous
fermentation of beer and SCP.

36. Rotary drum reactor:

37.  In this bioreactor only 40 % cylindrical drum is filled with
nutrients and rotated by means of rollers or motor.
 They are equipped with an inlet and outlet for circulation of
humidified air and often contain baffles to agitate the
contents.

38. Advantages of Rotary Drum Reactor:
 High oxygen transfer.
 Good mixing facilitates better growth.
 It is particularly suitable for the cultivation of the plant cell
cultures.

39. Disadvantages of Rotary Drum Reactor:
 Poor yield.
 Their main disadvantage is that the drum is not filled to
capacity (only 30% or 40% capacity) other wise mixing is
inefficient.

40. THANK U……….