THE THE AIR LIFT AIR LIFT

FERMENTEFERMENTERSRS

INTRODUCTION…

Type of fermenters that are impeller-free systems.

Employ forced/ pressurised air to circulate cells and nutrient medium.

Can be used to culture cells that highly shear-sensitive.

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.

PARTS OF ALR…

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.

Types of Gas separators in Internal loop ALRS

Types of Gas separators in External loop ALRs

TYPES OF ALRs….

Internal Loop reactor

External Loop reactor

ADVANTAGES OF ALRs… Sparger has 2 functions: Aeration as well as

Agitation. Hence, homogenous mixing/ distribution of gas/

oxygen. Homogenous distribution of nutrients and shear

force. No focal points of energy/ heat dissipation- no

agitator or stirrer. Key factors: Regulation of air bubble size Bubble residence time Liquid circulation and Gas injection.

MODIFICATIONS OF ALRs…

USES….

Mammalian cell cultures.

Waste water treatment

Biological processes involving biocatalysts as solids

To produce biopharma proteins etc from fragile cells.

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