bioreactors brief structure

1. Bioreactors
Design and construction of bioreactor
By
Deya
4thyear
VII th sem
M.Sc, integrated biotechnology
SPMVV.

2. BIOREACTOR
• Bioreactor is a vessel for the growth of
microorganisms( fermentation).
• Bioreactors provide the aseptic condition for
fermentation by not permitting
contamination.
• A bioreactor can be defined as an
apparatus, such as a large fermentation
chamber, for growing organisms such as
bacteria or yeast that are used in the
biotechnological manufacture of substances
such as pharmaceuticals, antibodies, or
vaccines, or for the bioconversion of
organic waste.

3. Fermentation
 Fermentation is a metabolic process that
converts sugar to acids, gases or alcohol.
 It occurs in yeast and bacteria, but also in
oxygen-starved muscle cells, as in the case
of lactic acid fermentation.
 Fermentation is also used for the bulk
growth of microorganisms on a growth
medium, often with the goal of producing a
specific chemical product.
 The science of fermentation is known as
zymology.

4. BASIC PRINCIPLES OF
BIOREACTORS DESIGN

5. introduction
The function of the bioreactor is to provide a
suitable environment in which an organism
can efficiently produce a target product .
 Cell biomass
 Metabolite
 Bioconversion Product

6. The performance of any bioreactor depends on
the following key factors:
• Agitation rate
• Oxygen transfer
• pH
• Temperature
 Foam production
The design of a bioreactor should consider the
following factors:
• the production organism
• the optimal operating condition required for target
product formation,
• product value
• scale of production.
• capital investment

7. Requirements of Bioreactors
 The design and construction of bioreactors must keep
sterility from the start point to end of the process.
 Optimal mixing with low, uniform shear.
 Adequate mass transfer, oxygen.
 Clearly defined flow conditions.
 Feeding substrate with prevention of under or
overdosing.
 Suspension of solids.
 Gentle heat transfer.
 ability to be sterilized for long term;
 simple construction;
 simple measuring, control,
 scale-up &flexibility;
 compatibility with up- downstream processes;

8. Requirements for bioreactor design
The basic points of consideration while
designing a fermentor:
• Productivity and yield
• Fermentor operability and reliability
• Product purification
• Water management
• Energy requirements
• Waste treatment
• Operation should be contamination free

9. Bioreactor design
In olden days ,traditional design is open cylindrical or
rectangular vessels made from wood or stone.
Most fermentations are now performed in close system to
avoid contamination.
It should be constructed from non-toxic, corrosion-
resistant materials.
Small fermentation vessels of a few liters capacity are
constructed from glass and/or stainless steel.
A good fermenter should have:
 Heat and oxygen transfer configuration
 Sterilization procedures
 Fast and thorough cleaning system
 Proper monitoring and control system

10. CONSTRUCTION OF BIOREACTORS

11. Bioreactor construction required:
 Steel/glass vessel
 Agitator (impeller)
 Baffles
 Sparger
(aeration system)
 Temperature probe
 PH probe
 Foam probe
 Cooling jacket
 Heating coil
 Dissolved oxygen
 Pressure

12. Steel/glass vessel
 In starting wooden or
rock vessels are
used for
fermentation
process, they are
lack of aseptic
condition.
 In modren
bioreactors glass or
steel vessels are
used
 Industrial vessels are
constructed of

13. AERATION
&
AGITATION
Make uniform suspension of microbial cells in homogeneous
nutrient medium and provide sufficient oxygen .

14. Impeller ( agitator)
 Mounted to a shaft
through a bearing in
the lid
 Driven by an external
power source or direct
drive
 Direct drive - action
varied by using
different impeller
blades
 Spining of medium in
circular direction

15. By Mixing objectives it achieve
 Bulk fluid &
gas phase mixing
 Air dispersion
 O2 transfer
 Heat transfer
 Suspension of solid
particles
 Maintenance of
uniform environment
throughout the
vessel.

16. Basffles
 Four baffles are normally
incorporated into agitated
vessels of all sizes to
prevent a vortex and to
improve aeration efficiency.
 Baffles are metal strips
roughly one-tenth of the
vessel diameter and
attached radially to the wall.
 recommended that baffles
should be installed so that a
gap existed between them
and the vessel wall, so that
there was a scouring action
around and behind the
baffles thus minimizing
microbial growth on the
baffles and the fermentor
walls.

17. Sparger
(aeration system)
 A device that introduce
air into medium
 Has a pipe with minute
holes (1/64 - 1/32 inch
or large)
 Hole – allows air under
P to escape into
medium
 Impeller blades
disperses air released
through sparger into
medium

18. Porous sparger
 Made of sintered glass,
ceramics or metal
 Used mainly on a large
scale fermentors
 Bubble size produced –
10-100 times larger than
pores
 There is also the problem
of the fine holes
becoming blocked by
growth of the microbial
culture.

19. Orificie sparger
 In small stirred fermentors 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.
 Sparger holes should be at
least 6 mm (1/4 inch) diameter
because of the tendency of
smaller holes to block and to
minimize the pressure drop.

20. Nozzle sparger
 Modern mechanically
stirred fermentors use
them
 Single open or partially
closed pipes
 Ideally, positioned
centrally below impeller
 no clogging of pores

21. Control
&
monitoring
probes
In-situ methods are developed to process closer control and
monitoring.

22. Temperature probe
 Maintaining a required
temperature for microbial
growth is essential for good
yield.
 Fluctuation in temperature
may cause damage to
microorganisms .
 Cultivation temperature is
normally monitored with an
accuracy +/-5*c
 Temperature affects the
solubility and diffusivity of
oxygen in the fermentation
broth.
 Measurement rang of 20
upto 180oC
 Electrode body made of
stainless steel and highly
measuring sensitivity.

23. PH probe
 Only sterilizable
electrodes are
used
 Electrode body is
made of glass
 Measurement
range 0 upto13
 High sensitiveness
 The control of pH
values is ensured
with the help of
peristatic pumps.

24. Foam checking probe
 The appearing of
foam is very
undesirable
phenomenon, since
there is a risk to lose
an essential part of
fermentation broth.
 During foaming it is
not possible to
perform high quality
analysis and
measurements.

25. Elimination of foam
Additional metering of antifoam
based on sensor Mechanical metering of foam
 Probe is inserted through
top of bioreactor
 Stainless steel rod set at
a defined levels above
the broth surface
 When foam rises and
touched the probe tip
,pump is activated and
antifoam is released into
bioreactor.
 Mechanical antifoam
devices:
 Discs
 Propellers
 Brushes
 Hollow cones
 They are attached to
agitator shaft above the
broth surface
 Foam is broken down when
it is thrown against the
walls of the bioreactors.

26. Cooling jacket
 Cooling jacket is filled
with cool water
 Water jacket circulates
cooling water to
remove the heat
produced by microbial
activity
 It prevents the
denaturation of
enzyme
 It used to cool down
the reaction so it can
come to optimal
condition

27. Heating coil
 Heat will be produced
by the microbial activity
and agitation
 If heat generated by
these two process is not
ideal for manufacturing
process then heat may
be provided by
◦ Placing fermentor in a
thermostatically controlled
bath
◦ By internal heating coils
◦ By silicone heating jacket
◦ By circulating hot water
around the tank in jacket

28. Pressure
 Industrial bioreactors are designed
to withstand a specific working
pressure
 Pressure measurements are
required as a factor of safety
 It is important to fit the equipment
with devices that sense ,indicate,
and control pressure
 Pressure measuring sensors:
Bourdon tube pressure gauge
Diaphragm gauge
Piezoelectric transducer
 The correct pressure is
maintained by regulatory values
controlled by associated pressure

29. Dissolved oxygen
 Measured by DO
probe
 DO electrodes
measured partial
pressure of dissolved
oxygen
 Electrodes are made
up of stainless steel
and high responsitivity
 Function according to
Clark principle
 In event of low oxygen
tension in broth ,and
agitator speed is
increased.

30. Conclusion
 It is observed that various bioreactor
configurations effect the production rate of
fermentation
 Various factors like vessel shape, agitation,
aeration, baffles etc., play major role in
productivity
 There is no bioreactor which can satisfy all
the conditions
 There are other novel approaches are
developed to increase productivity of
spargers, agitators, as well as various
controlling probes in order to improve
productivity of bioreactors.