This document describes the airlift bioreactor, which uses forced air circulation to mix cells and nutrients without mechanical agitation. It has an inner riser region where air is injected upwards, and an outer downcomer region where degassed media and cells circulate downwards. The density gradient between these regions drives continuous fluid circulation. The bioreactor has a gas separator, sparger, and headspace to introduce air, separate gases, and allow foaming. It is useful for culturing shear-sensitive cells as it provides gentle mixing with low energy use.

1. AIR LIFT
BIOREACTOR
BEENISH SARFRAZ

2. INTRODUCTION…
 typical motionless bioreactor where the internal
circulation and mixing are achieved by bubbling air.”
 Employ forced/ pressurized air to circulate cells and
nutrient medium.
 Can be used to culture cells that highly shear-sensitive.
 gas stream facilitate exchange of material between the gas
phase and the medium.
 oxygen is usually transferred to the liquid, products are
removed through exchange with the gas phase.

3. STRUCTURE/ DESIGN…
 Entire reactor is divided into 2 halves by a Draft tube:
 inner gassed region ( Riser)
 outer ungassed region ( Down comer)
 Riser has gas injection connected- air moves upwards.
 Down comer region has degassed media and cells.
 Mean density gradient between riser and downcomer
regions causes continuous circulation.

5. PARTS OF ALR… upward air flow.
 RISER: Connected gas injection-
 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.

6. ALR TYPES DESCRIPTION
 INTERNAL LOOP ALR:
 baffles placed strategically in a single vessel create the
channels required for the circulation
 shortest path that a bubble cover from the riser to the
downcomer is a straight line
 EXTERNAL LOOP ALR: circulation takes place through
separate and distinct conduits
 there is usually a minimum horizontal distance to be
covered, increases the chances of disengagement of the
bubbles

8. TYPES OF ALRs….

9. Types of Gas separators in Internal external
loop ALRS

10. HOW AIRLIFT BIOREACTOR WORKS?
Headspace
region
downcomer
riser
Grooved nozzle
bank

11. Gas
separator
downcomer riser

12. ALR features
 Gas separator
 Gas Holdup
a) Driving force circulation
 Shear stress
 Effect of liquid
a) Disengement of bubbles
• Free rising velocity, liquid velocity, residence time of bubbles in gas
separator
 Measuring The Liquid Velocity.
 use of tracers in the liquid. If a tracer is injected and two probes are installed in
a section of the tube

13. AIRLIFT REACTOR
CHARACTERSICTICS
 Liquid Mixing
 Mass Transfer
 Rate of gas transfer across gas
liquid interface per unit of driving
force.
 Energy Dissipation

14. MODIFICATIONS OF ALRs…

15. ADVANTAGES OF ALRs…
Hence, homogenous mixing/ distribution of gas/ oxygen.
 Simple design with no moving parts or agitator for
less maintenance, less risk of defects.
 Easier sterilization (no agitator shaft parts)
 Low Energy requirement Homogenous distribution of
nutrients and shear force.
 DISADVANTAGES
 Greater air throughput and higher pressures needed
 Inefficient break the foam when foaming occurs
 NO bubbles breaker

16. USES….
 Mammalian cell cultures.
 Waste water treatment
 Biological processes involving biocatalysts as solids
 To produce biopharma proteins etc from fragile cells.