Fermenters

1. .

2.  A fermenter or fermentation chamber is a closed vessel
with suitable organization for agitation, aeration, pH
and temperature control and inlet and outlet to add
nutrients and to remove the waste biomass along with
their products.

3. 1. Stirred fermenter
2. Airlift fermenter
3. Tower fermenter
4. Waldhof fermenter

4.  For laboratory experiments vessel of volume up to 20 liters
are made of glass.
 For larger vessels, construction is made of stainless steel.
 A mechanically stirred fermenter fitted with
(i) a sparger and
(ii) a Rushton turbine

5. Working volume
 The fraction of the total volume
taken up by the medium,
microbes, and gas bubbles.
 Typically, Working volume is 70-
80% of the total fermenter
volume.
 The remaining volume is called
the headspace volume.

6.  An agitator system
 An oxygen delivery system
 A foam control system
 A temperature control system
 A pH control system
 Sampling ports
 A cleaning and sterilization system.
 A sump and dump line for emptying of the reactor

8.  The function of the agitation system is to
 Provide good mixing
 Increase mass transfer rates
 Provide the appropriate shear conditions.
 The agitation system consists of the
 Agitator
 Baffles

9. • Two types of agitator are used
(i) bottom entry impellers and
(ii) top entry impellers
• Top entry impeller shaft enter
from the top of fermenter
(overhung shaft).
• More expensive to install as the
motor and the shaft will need to
be structurally supported.
,

10. • Bottom entry impeller shaft
enter from the bottom of
fermenter
• Tend to require more
maintenance.
• The number of impellers is
depend on the height of the
liquid in the reactor.

11.  Used to produce liquid slurry
turbulence to reduce foam formation
 Used to obtain:
Better retention of air
Better mixing
Better suspension of solid
 Fixed on the internal walls of
fermenter
 Convert large bubbles into smaller
bubbles, so less amount of antifoam
required.

12.  Prevent contaminants from entering the reactor
 Prevent organisms from escaping through the shaft
 Uses vapors from the liquid for lubrication.

13.  The oxygen delivery system consists of
1. A compressor
2. Inlet air sterilization system
3. An air sparger
4. Exit air sterilization system

14. .
Compressor
 Forces the air into the reactor.
 Needed sufficient pressure to force the air through the filter,
sparger holes and into the liquid.
Air sterilization system
 Inlet air prevent contaminants from entering in the reactor.
 Exit air sterilization prevents organisms in the reactor from
contaminating the air.
 A common method of sterilizing the inlet and exit air is
filtration.
 Teflon membranes are used, Teflon is tough, reusable and
does not readily block.

15.  Used to break the incoming air into small bubbles.
 Most common sparger ring (a hollow tube with small holes).
 Easier to clean and is less likely to block during fermentation.
 Located below the agitator
 Have approximately the same diameter as the impeller.
 Thus, the bubbles rise directly into the impeller blades,
facilitating bubble break up.

16. .
• Simple heat exchanger through which cool water is
passed.
• Volatile materials and water vapors condense on the
inner condenser surface.
• This minimizes water evaporation and the loss of
volatiles.
• Drying the air also prevents blocking of the exit air
filter with water.

17. Without aeration, a vacuum
forms as the reactor cools.
With aeration, positive
pressure is always maintained
and contaminants are pushed
away from the reactor

18.  Excessive foam formation can lead to
Blocked air exit filters
Pressure build up in the reactor
Loss of medium
Damage to the reactor and
Even injury to operating personnel.
 Controlled with aid of antifoaming agents such as
silicone.
 Excessive antifoam addition can however result in
poor oxygen transfer rates.

19. When the upper level probe is above the foam level, no
current will pass between the level probes and the
antifoam pump remains turned off.
When the upper level probe is immersed in the
foam layer, a current is carried in the foam. This
causes the antifoam to turn on.

20.  Temperature control system consists of
1. Temperature probes
2. Heat transfer system
 Typically the heat transfer system is
used a "jacket" to transfer heat in or out
of the reactor.
 Probes may give rise to localized zones
of high temperature.
 The jacket is a shell which surrounds part
of the reactor.
 The liquid in the jacket does not come in
direct contact with the fermentation fluid.

21. • The pH control system consists of
1. A pH probe
2. Alkali delivery system
3. Acid delivery system
• The pH probe is typically steam sterilizable

22.  Tower fermenter or column fermenter.
 Simple design with no moving parts or agitator
 Less maintenance,
 Less risk of defects.
Easier sterilization
Low Energy requirement
 Large size fermenters, Glass or plastic vessels.
 Can be used to culture cells that highly shear-sensitive.

23.  Entire reactor is divided into 2
halves by a Draft tube:
 inner gassed region ( Riser)
 outer ungassed region ( Down
comer)
 Mean density gradient between
riser and downcomer regions
causes continuous circulation.

24.  RISER: Connected gas injection- upward air flow.
 DOWNCOMER: degassed media+cells.
 BASE: Connected to Perforated nozzle bank/ plate/
 Sparger to pump pressurized air.
 HEAD SPACE: Gas release region, flocculation, foam
 accumulation etc.
 GAS SEPARATOR:
Facilitates gas/liquid recirculation
Maximizes gas residence time
Reduces gas friction in downcomer.

25.  There are essentially four design variants. These are;

26.  The processes in which product formation is depend on the
temperature, two stage airlift fermenters are used.
 Two fermenters one having temperature at 30 °C and the other
having temperature at 42°C are used.
 From one fermenter (30°C) growing cells are pumped into
another fermenter (42°C).
 It is difficult to increase the temperature of same vessel from
30°C to 42°C immediately.
 Both vessels are connected to each other by pump and transfer
tubes.
 Growth of microorganism occur in first vessel at 30 °C and the
proper bioprocessing occur in second bioreactor

28.  Steam generator
 Simple as compared to stirred fermenter
 Different airfilter at inlets and outlets are present to
prevent contamination.

29.  Mammalian cell cultures.
 Waste water treatment.
 Biological processes involving biocatalysts as solids.
 To produce biopharma proteins from fragile cells.