Description about Airlift Fermenter

1. SAM HIGGINBOTTOM UNIVERSITY OF
AGRICULTURE TECHNOLOGY AND
SCIENCES
PRAYAGRAJ, U.P,211008
Prepared By:
Ravi Rastogi
16BPH081
AIRLIFT FERMENTER
Submitted to:
DR. SONAM BHATIA
FHS,SHUATS

2.  A bioreactor 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.
 The major difference between fermenter and bioreactor is that
the bioreactor is a vessel that facilitates various types of
biochemical reactions whereas fermenter is the vessel facilitating
fermentation only.
 Therefore, fermenter is only a type of bioreactor.
BIOREACTOR

3. Introduction:
 Air Lift (or Gas Lift) bioreactors are an alternative to
mechanically agitated systems that reduce shear stress and heat
generation by eliminating the mechanical agitator.
 It is a pneumatic system and a batch process system.
 Two types of airlift fermenters :
A. Internal loop airlift bioreactor
B. External loop airlift bioreactor
Internal loop bioreactor has a single container with a central draft
tube that creates interior liquid circulation channels.
External loop bioreactor possesses an external loop so that the liquid
circulates through separate independent channels.
Airlift Bioreactor

5.  In a typical airlift bioreactor,
entire reactor is divided into 2
halves by a Draft tube:
 inner gassed region ( Riser): gas
is passed through it.
outer ungassed region ( Down
comer)
 Mean density gradient between
riser and downcomer regions
causes continuous circulation.

6.  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.

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

8. Working mechanism:
• An airlift bioreactor works by agitating the contents of the
bioreactor pneumatically using gas. The gas used for
agitation can act to either, introduce new molecules to the
mixture inside of the bioreactor, or remove specific
metabolic molecules produced by microorganisms
• Airlift bioreactors have a built in bubble column designed
to release gas into the bioreactor. Gas is usually injected
into the bubble column at the bottom of the bioreactor
.
• Mixing occurs as the bubbles rise through the bubble
column to the top of the bioreactor.

9. • There are two separate channels within an airlift
bioreactors; one channel for gas/liquid up-flow and
one channel for gas/liquid down-flow.
• Both channels create a closed gas/liquid circuit,
and has a mechanism for removing gaseous
substances at the top of the bioreactor called the
gas separator. 

10.  It has a single container with a central draft tube.
 Simple in design.
 No temperature variation as in two stage bioreactor.
 No separate reactors or chambers for growth and
bioprocesses. Both occur in the same reactor.
 Not suitable for temperature dependent formation of
products as it is difficult to fluctuate temperature in a
same vessel unlike two tower airlift bioreactor.
TOWER BIOREACTOR

11.  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

12.  Steam generator
 Different airfilter at inlets and outlets are present to
prevent contamination.

13.  For aerobic bioprocessing technologies.
 Due to high efficiency, airlift bioreactors are sometimes
preferred for the processes like methanol production
and waste water treatment.
 Biological processes involving biocatalysts as solids.
 To produce single cell proteins from fragile cells.
USES:

14. Advantages:
• Simple design with no moving parts or agitator for less
maintenance, less risk of defects
.
• Easier sterilization (no agitator shaft parts)
• Low Energy requirement vs stirred tank : Obviously
doesn’t need the energy for the moving parts (agitator
shaft).
• Very low cost as no mechanical agitators and extra
cooling equipment are required.
• Ideal for the aerobic cultures since oxygen mass transfer
coefficient is high.

15. • Greater heat-removal vs stirred tank: At the Airlift
bioreactor it doesn’t need the heat plate to control the
temperature, because the Draught-Tube which is inside
the bioreactor can be designed to serve as internal heat
exchanger. It is difference to the Stirred tank bioreactor
that needs the heat coat or plate surrounding the tank to
make warm bioreactor. It is clear enough that the
Airlift bioreactor has greater heat-removal compare to
Stirred tank
• Low shear therefore can be used for plant and animal
cells
.

16. Disadvantages:
• Inefficient in breaking of foams when foaming occurs
due to lack of blades/shafts as compared to stirred tank.
• No bubble breakers which are produced from air
supply(sparger)
• Greater air throughput and higher pressures
needed : The agitation on the Airlift bioreactor is
controlled by the supply air. To adjust the supply air
then the higher pressure needed. And if the higher
pressure of air needed then more energy consumption
needed. And more cost must pay.

17. REFERENCES:
 http://www.biologydiscussion.com/biotechnology/bioprocess-
technology/bioreactors-types-6-types-of-bioreactors-used-in-
bioprocess-technology/10090
 https://www.sciencedirect.com/topics/engineering/airlift-
bioreactors

18. THANK YOU !