STRUCTURE OF A LABORATORY FERMENTER & ITS APPLICATIONS

1. STRUCTURE &
APPLICATIONS OF A
FERMENTER
PRESENTED BY :
Tanishka (211206)
MSc. Biotechnology
3rd semester,2nd year

2. BASIC FUNCTIONS OF FERMENTER:
Provide a controlled environment for the growth of microorganisms
or animal cells, to obtain a desired product.
• Vessel - aseptically reliable in long-term operation
• Adequate aeration and agitation
( mixing should not cause damage to the organism nor cause excessive
foam generation).
• Power consumption - as low as possible.
• System for temperature control
• System of pH monitoring and control & other parameters (eg,
dissolved oxygen, redox, etc.)

3. • Sampling facilities
• Evaporation losses from the fermenter should not be excessive.
• Require the minimal use of labor in operation, harvesting, cleaning,
and maintenance.
• Ensure smooth internal surfaces, using welds inside the vessel
• Vessel should be of similar geometry to both smaller and larger vessels
• Use of cheapest material enabling satisfactory results
• There should be adequate service provisions for individual plants.

5. ASPETIC OPERATION & CONTAINMENT
Aseptic operation protection against contamination
containment prevention of escape of viable cells
from a fermenter or downstream equipment.
To establish the appropriate degree of containment ,the entire
process must be carefully assessed for potential hazards that could
occur in case of accidental release.

6. HAZARD ASSESSMENT SYSTEM:
• Once the organism has been allocated to a hazard group, the
appropriate containment requirements can be applied.
• Hazard group 1 organisms used on a large scale only require.
• Processes in this category need to be operated aseptically but no
containment steps are necessary, including prevention of escape of
organisms.
• If the organism is placed in Hazard group 4 the stringent
requirements of level 3 will have to be met before the process can be
operated.

7. Good Industrial Large Scale Practice (GILSP)

8. Hazard group criteria :
• known pathogenicity
• virulence or level of pathogenicity
• number of organisms required to initiate an infection.
• routes of infection.
• The amounts or volumes of organisms used in the fermentation
process etc.

9. FERMENTER BODY CONSTRUCTION - VESSEL
CHARACTERSTICS:
• Withstand pressure sterilization
• Corrosion proof
• Non-toxic
• Less cost

10. • The American Iron and Steel Institute (AISI) states that :
• Mild steel coated with glass or phenolic epoxy materials has
occasionally been used.
• Chromium provides resistance from the corrosion & the minimum
amount of chromium required depends on the corroding agent in a
particular environment, such as acids, alkalis, gases, soil, salt, or fresh
water.
Steels
<4% chromium
>4% chromium
STEEL
ALLOYS
STAINLESS
STEELS

12. SEAL:
• a reliable aseptic seal is made between a fermenter vessel and a
detachable top or base plate.
• This seal ensures that a good liquid- and/or gas-tight joint is maintained in
spite of the glass or metal expanding or contracting at different rates with
changes in temperature during a sterilization cycle or an incubation cycle.
• Nitryl or butyl rubbers are normally used for these seals as they will
withstand fermentation process conditions.
• These rubber seals have a finite life and should be checked regularly for
damage or perishing.

13. TYPES OF SEAL :

14. TEMPERATURE CONTROL
Heat produced due to of :
• microbial activity
• mechanical agitation
Which is not ideal for the
particular manufacturing
process
So, heat may have to be added, or
removed from the system.
On laboratory scale,
addition/removal of heat occurs
by :
 placing the fermenter in a
thermostatically controlled bath
 use of internal heating coils
 a heating jacket through which
water is circulated.

15. Accurate estimation of heating/cooling requirements:
Where
Qmet- heat generation rate due to microbial metabolism
Qag - heat generation rate due to mechanical agitation
Qgas - heat generation rate due to aeration power input
Qacc - heat accumulation rate by the system
Qexch - heat transfer rate to the surroundings and/or heat exchanger
Qevap - heat loss rate by evaporation
Qsen - rate of sensible enthalpy gain by the flow streams (exit—inlet)

16. AERATION & AGITATION
to provide microorganisms
in submerged culture with
sufficient oxygen for
metabolic requirements
ensure uniform suspension of
microbial cells is achieved in a
homogeneous nutrient
medium.
The structural components of the fermenter involved :
a. The agitator (impeller).
b. Stirrer glands and bearings.
c. Baffles.
d. The aeration system (sparger)

17. IMPELLER:
Required:
• bulk fluid and gas-phase mixing
• oxygen transfer
• heat transfer
• suspension of solid particles
• maintaining a uniform environment throughout the vessel contents.

18. • Disc turbines: They comprise
disc with a set of rectangular
vanes. They allow an air stream
from the sparger to strike on the
disc’s underside and then move
the air toward the vanes,
breaking large air bubbles down
into smaller ones.
• Variable pitch open
turbine: They also comprise a
an agitator shaft that is vanned
and joined to propeller blades of
the marine on the shaft for the
agitator. The air bubbles that
make up this turbine don’t touch
any surface prior to dispersing

19. STIRRER GLANDS & BEARINGS:
• The satisfactory sealing of the stirrer shaft assembly top
plate has been one of the most difficult problems to
overcome in the construction of fermentation equipment
which can be operated aseptically for long periods.
• The stirrer shaft can enter the vessel from the top, side or
bottom of the vessel.

21. EARLIEST STIRRERS SEAL :
• A porous bronze bearing for a 13-mm shaft was fitted in
the centre of the fermenter top and another in a yoke
directly above it.
• The bearings were pressed into steel housings, which
screwed into position in the yoke and the fermenter top.
• The lower bearing and housing were covered with a skirt-
like shield having a 6.5 mm overhang which rotated with
the shaft and prevented air- borne contaminants from
settling on the bearing and working their way through it
into the fermenter.

22. Four basic types of seal assembly have been used:
• the stuffing box (packed-gland seal)
The shaft is sealed by several layers of packing rings of asbestos or
cotton yarn, pressed against the shaft by a gland follower
• the simple bush seal
• the mechanical seal
• the magnetic drive
Most modern fermenter stirrer mechanisms now incorporate
mechanical seals instead of stuffing boxes and packed glands.

23. Mechanical seals are more expensive, but
are more durable and less likely to be an
entry point for contaminants or a leakage
point for organisms or products which
should be contained
Seal is composed of two parts, one part is stationary in
the bearing housing, the other rotates on the shaft, and
the two components are pressed together by springs or
expanding bellows.
The two meeting surfaces have to be precision
machined, the moving surface normally consists of a
carbon-faced unit while the stationary unit is of stellite-
faced stainless steel.

24. Magnetic drives, which are also quite
expensive, have been used in animal cell
culture vessels.
The problems of providing a satisfactory seal
when the impeller shaft passes through the top
or bottom plate of the fermenter may be solved
by the use of a magnetic drive in which the
impeller shaft does not pierce the vessel.
• A magnetic drive consists of two magnets:
one driving and one driven.

25. BAFFLES :
• Four baffles are normally incorporated into agitated vessels of all sizes
to prevent a vortex & to prevent aeration efficiency.
• In vessels over 3-dm3 six or eight baffles may be used.
• Baffles are metal strips roughly one-tenth of the vessel diameter and
attached radially to the wall
• The agitation effect is only slightly increased with wider baffles, but
drops sharply with narrower baffles.

28. SPARGER:
• a device for introducing air into the liquid in a fermenter.
• A combined sparger-agitator may be used in laboratory fermenter.
• Three basic types of sparger:
• the porous sparger
• the orifice sparger (a perforated pipe)
• the nozzle sparger (an open or partially closed pipe)

29. POROUS SPARGER:
The porous sparger of sintered glass, ceramics or metal, has
been used primarily on a laboratory scale in non-agitated
vessels.
• The bubble size produced from such spargers is always 10
to 100 times larger than the pore size of the aerator block.
• There is also the problem of the fine holes becoming
blocked by growth of the microbial culture.

30. ORIFICE SPARGER:
• In small stirred fermenters the perforated pipes were
arranged below the impeller in the form of crosses or rings
(ring sparger), approximately three-quarters of the impeller
diameter.
• In most designs the air holes were drilled on the under
surfaces of the tubes making up the ring or cross.

31. NOZZLE SPARGER:
• Single open or partially closed pipe as a sparger to provide
the stream of air bubbles.
• Ideally the pipe should be positioned centrally below the
impeller and as far away as possible from it to ensure that
the impeller is not flooded by the air stream.

32. COMBINED SPARGER
AGITATOR:
• introducing the air via a hollow agitator
shaft and emitting it through holes drilled
in the disc.
• The design gives good aeration in a baffled
vessel when the agitator is operated at a
range of rpm.

33. FEED PORTS :
• to add ingredients at the right times.
• to monitor fermentation process continuously and makes it
easy to add nutrients or remove byproducts.
• consist of tubes made of silicone.
• In-situ sterilization is carried out prior to either the removal or
the addition of ingredients.

34. FOAM CONTROL :
• volume of foam within the vessel must be reduced to prevent
contamination.
• The level of foam can be controlled with two components:
foam sensing and control.
• In the fermenter the probe is placed through the top and is set
to a certain level that is above the surface of the broth.
• If the level of foam rises and it touches the probe’s tip there will
be a current carried across the circuit.
• The current will activate the pump, and antifoam will be
released immediately to fight the issue.

35. VALVES
• Valves are employed in the fermenter for controlling the flow of
liquid inside the vessel.
• There are around five kinds of valves :
• Globe valves can be used for general use, but they don’t control
flow.
• Butterfly valves are not appropriate for use in aseptic conditions.
They are utilized for pipes with large diameters that operate at low
pressure.
• Ball valves can be used in aseptic conditions. They can handle
mycelial broths and operate at a high temperatures.
• Diaphragm valves aid in adjusting flow.

36. SAFETY VALVE:
• The safety valve is integrated into the pipe and air layout to
function under pressure. Through these valves, the pressure
remains within the safe boundaries.

37. CONTROLLING DEVICES FOR
ENVIRONMENTAL FACTORS :
• Bioreactor design must consider many parameters such as
temperature, pH, dissolved oxygen and carbon dioxide
concentrations.
• all be controlled at certain levels during the process.
• will control growth, reduce contamination, improve production
rate and increase product-quality.
• These devices will enable us to monitor the temperature,
carbon dioxide, oxygen concentration, and pH of the reactor at
any time.

38. APPLICATIONS

40. REFERENCES:
• PRINCIPLES OF FERMENTATION TECHNOLOGY BY PETER F.STANBURY,
ALLAN WHITAKER & STEPHEN J. HALL
• https://microbenotes.com/bioreactor/#applications-of-bioreactor