The document discusses different types of fermenters used in biological processes. It explains that fermenters provide an optimal environment for microorganisms to interact with substrates and form desired products. There are two main types - open and closed fermenters. Key requirements for fermenters include maintaining sterile conditions, effective mixing through aeration and agitation, and monitoring environmental factors like pH, temperature and dissolved oxygen. Common mixing mechanisms used are disc turbines, vaned discs, and propellers attached to agitator shafts. Spargers are also discussed for introducing air into the fermentation broth.

1. Priyanka Nawal
Assistant Professor
DY Patil College of ASC
Pune

2.  A fermenter or Bioreactor is a container
designed to provide an optimum environment in
which microorganism or enzymes can interact
with a substrate and form the desired product.
 It is a system in which biological system is
effected.
 Fermenter are of two types:-
A) Open
B) Closed
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6.  It has to fulfill a number of requirements:-
1) A sterile Environment
2) Biomass Concentration
3) Access for environment monitoring like pH,
Temperature, dissolved oxygen, pressure etc.
4) Provision for sampling
5) Provision for addition of Antifoam agents, acid, base,
fresh medium etc.
6) Effective agitation and aeration.
7) Product removal
8) Product inhibition
9) Metabolism and metabolic activities
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7.  Aeration-Primary purpose of aeration is to
provide microorganisms in submerged culture
with sufficient oxygen for metabolic
requirements.
 Agitation-Agitation should ensure that a
uniform suspension of microbial cells is
achieved in a homogeneous nutrient medium.
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9.  Iron
 Susceptible to corrosion.
 12.5% added to chromium to the iron.
 Chromium + Oxygen = Chromium Oxide
(Layer)
 Steel at room temperature is Ferrite based
iron – Alpha iron
 Non magnetic Austentine – (gamma iron)
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Heated @ 910ᵒC

10.  Stainless steels have traditionally been divided into
types depending on their microstructure at room
temperature, which gives a rough indication of their
composition and properties.
 Outokumpu's stainless steels can be divided into four
main types:
1) Ferritic,
2) Ferritic Austenitic
3) Ferritic Martensitic and
3) Austentic
 The best steel for you depends on the application.
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11.  Chrome steel ( Cr-14-25%, C- 0.05-0.2%)
 Low carbon and nickel content
 Low corrosion resistance
 Good weldability and toughness
 Magnetic
 For house hold equipment (knives, sinks)
turbines etc.
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12.  Chrome-Nickel steel (Cr – 26%, C - 0.08%,
Ni – 4.5%)
 Heat resistancent
 Casting quality
 For Cast industrial equipments, valves,
pumps
 Magnetic
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13.  Chrome steel ( Cr – 5- 17%, C – 0.08- 0.3%)
+ Mo, Ni)
 Heat resistance and mechanical rigidity
 Hard to weld
 For household equipment
 Magnetic
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14.  Chromium-Nickel- Molybdenum steel
 Chromium- Nickel steel
 High Corrosion and resistant
 Easy to weld
 For chemical, Food leaching
 In Sulphite industries
 Non Magnetic
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15.  It is required to achieve a number of mixing objectives
e.g.-
-Oxygen transfer
-heat transfer
-suspension of solid particles
-maintaining a uniform temperature
-Create local turbulence
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16.  These objectives are achieved by a suitable
combination of the most appropriate agitator, air
sparger and baffles, and the best positions for
nutrient feeds, acid or alkali for pH control and
antifoam addition.
 Agitators are of several different types,
e.g., (i) Disc turbines,
(ii) Vaned discs,
(iii) Open turbines of variable pitch and
(iv) Propellers.
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Disc turbines, Vaned discs, open turbines of variable pitch, and
propelleres are used in fermenter.

18.  Disc turbine consists of a disc with a series of rectangular vanes
set in a vertical plane around its perpheri (Fig. 14.1 A).
 The vaned disc turbine has a series of rectangular vanes attached
vertically to the underside of the disc (Fig. 14. 1B).
 In case of variable pitch open turbine, the vanes are attached
directly to a boss on the agitator shaft (Fig. 14.1C).
 The marine propeller is similar to variable pitch open turbine,
except that it has blades in the place of vanes (Fig. 14.1D).
 In case of disc and vaned disc turbines, the air bubbles from the
sparger first-hit the underside of disc before being broken into
smaller bubbles and dispersed by the vanes.
 But in the case of the latter two types of agitators, air bubbles
contact the vanes/blades directly and arc broken up and
dispersed by them. These basic agitation devices have been
variously modified.
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19.  Four baffles are normally incorporated into
agitated vessels of all size to prevent a vortex.
 In vessel over 3-dm³ diameter 6 or 8 baffles
may be used.
 Baffles are metal strips roughly one tenth of
the vessel diameter and attached radially to
the wall.
 Agitation effect increased with wider Baffles.
 Cooling coils are attached to it.
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21.  Device for introducing air into the liquid in a
fermenter.
 Three basic types of Sparger are used.
-Porous sparger
-Orifice sparger [perforated pipe]
-Nozzle sparger [open or partially closed pipe]
-Combined sparger-agitator
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25.  On a small scale (1 dm3),developed the combined
sparger-agitator design, introducing the air via a
hollow agitator shaft and emitting it through
holes drilled in the disc between the blades.
 It is connected to the base of the main shaft.
 The design gives good aeration in a baffled vessel
when the agitator is operated at a range of rpm.
 In this case, the air is introduced via a hollow
agitator shaft.
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28.  In this case, the air is introduced via a hollow
agitator shaft, and it comes out through holes
drilled in the disc between the blades and
connected to the base of the main shaft.
 This design gives a good aeration in baffled
vessels over a range of agitator speeds
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29.  It provides a stream of air bubbles.
 The sparger should be as far below the impeller
as possible to avoid flooding of the impeller in a
stream of air bubbles.
 These spargers cause a lower pressure loss than
the other spargers and they are not easily
blocked.
 In small fermenters, a combined sparger-agitator
may be used..
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30.  Facility for sampling should be provided.
 It should have a system for monitoring and regulating
pH of the fermentation broth.
 Evaporation losses should be as low as possible.
 It should require a minimum of labour in
maintenance, cleaning, operating and harvesting
operations.
 It should be suitable for a range of fermentation
processes. But this range may often be restricted by
the containment regulations.
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31.  It should have smooth internal surfaces, and joints
should be welded wherever possible.
 The pilot scale and production stage fermenters
should have similar geometry to facilitate scale-up.
 It should be contrasted using the cheapest
materials that afford satisfactory results.
 There should be adequate service provisions for
individual plants.
 It should provide a controlled environment for
optimum biomass/product yields.
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32.  It should permit aseptic fermentation for a number
of days reliably and dependably, and meet the
requirements of containment regulations.
 Containment involves prevention of escape of viable
cells from a fermenter or downstream processing
equipment into the environment.
 It should provide adequate mixing and aeration for
optimum growth and production, without damaging
the microorganisms/cells.
 The power consumption should be minimum.
 It should provide easy and dependable temperature
control.
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34.  Produce SCP (single-cell protein) from methanol
as a carbon substrate.
 Mixing is accomplished without any mechanical
agitation.
 Airlift bioreactors are used for tissue culture
because the tissues are shear sensitive and
normal mixing is not possible.
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36.  Their main common feature appears to be their
height-diameter ratio i.e.10:1.
 The simplest types of fermenter are those that
consist of a tube which is air sparged at the base
(bubble columns).
 This type of fermenter was first described for
citric acid production on a laboratory scale (Snell
and Schweiger, 1949).
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Cross section of a
fermenter for
Penicillin production

38.  Good gas exchange, lack of foaming and limited
wall growth have been claimed with this
fermenter.
 Dawson has listed a number of potential
bacterial, fungal and yeast applications
including the batch production of a vaccine.
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40.  Stanbury; P.F. and A. Whitaker (1984)
Principles of fermentation Technology.
Pergamon. New York.
 Biochemical engineering and
biotechnology G.D Najafpour, Elsevier
2007 page no.145-150.
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