This document discusses various types of fermenters used in industrial fermentation processes. It describes 7 types of fermenters: 1) Waldhof fermenter, 2) Acetators and cavitators, 3) Tower fermenter, 4) Cylindro-conical vessels, 5) Air lift fermenter, 6) Deep jet fermenter, 7) The cyclone column. For each type, it provides details on their design, operating principles, and applications. The key advantages of each fermenter type for different fermentation processes are highlighted.

1. BY
M.Vharshini
2ND YEAR
B.Sc. BMS

2. 1. Waldhof fermenter
2. Acetators and cavitators
3. Tower fermenter
4. Cylindro-conical vessels
5. Air lift fermenter
6. Deep jet fermenter
7. The cyclone column
8. Rotating disc fermenter

3.  Yeast growth in sulphite waste liquor led to
the development of Waldhof fermenter.
 The fermenter was Carbon steel, clad in
stainless steel
 Diameter – 7.9m
 High-4.3m
 Central draught tube -1.2m in diameter
 Draught tube was held by tie rods attached
to the fermenter walls
 Operating volume—225,000dm3 of
emulsion(broth & air) and broth without air—
100,000dm3

4.  Non sterile air was introduced into the
fermenter using the rotating – pin wheel type
of aerator composed of open ended tubes
rotating at 300 rpm.
 The broth passed down the draught tube
from the outer compartment which reduced
the foaming.

6.  Fundamental studies on vinegar production showed that:
 Acetobacter cells remain active in stirred aerated
fermenter , distribution of air had to be almost perfect
within the entire contents of the vessel
 The full-scale problem was solved by the use of self
aspirating rotor— the turning rotor sucked air and broth
and dispersed the mixture through out the rotating stator.
 The aerator also worked without a compressor and was
self-priming.
 In Vinegar fermentation—foam & chemical antifoams are
not feasible because they decrease aeration efficiency and
quality of vinegar.
 Therefore Mechanical defoamer was incorporated into
vessels and as foam builds up it is forced into a chamber in
which the rotor runs at 1,000 to 1,450 rpm.

7.  Centrifugal force breaks the foam & separates it
into gas & liquid.
 The liquid is pumped back into the fermenter &
gas escapes by a venting mechanism.
 Uniform distribution of air bubbles was obtained
by means of the circulation pattern created by
the centrally located draught tube.

8.  A- hollow body of
turbine
 B-openings radially
arranged
 C-verticle sheets
 D-stator
 E & F-upper and
lower ring on the
turbine
 G & H-upper and
lower ring of stator

9.  An elongated non mechanically stirred
fermenter having the aspect ratio 6:1 for tubular
sections and 10:1 for overall, through which
there is a unidirectional flow of gases.
 Simple tower fermenter are those with air
sparger at the base ;used for citric acid
production
 This batch fermenter is in the form of glass
column having a ht:diameter ratio of 16:1 and
with a volume of 3dm3.
 Humid sterile air was supplied through the base.

10.  Single staged: e.g. Hall and howard’s beer
fermentor: water jacketed tubes of various
dimensions inclined at an angles of 9ºto90º.
 Intermediate staged: settling zones of
various designs e.g. Shore et al’s beer
fermentor. It has sectioned perforated plates
for max. beer production
 Multi staged: number of perforated vessels
are used. e.g.Owen (1948) and
victorero(1948) et al for brewing beer.

12.  Used in Brewing of lager.
 First proposed by Nathan.
 The vessel consists of stainless steel vertical
tube with a hemispherical top & conical base
with an included angle of approx 70 degree.
 Aspect ratio—3:1
 Fermenter Height—10 to 20m
 Operating volumes—150,000to 200,000dm3
 Vessels are not normally agitated unless
particularly flocculant yeast is used

13.  Small impeller may be used to ensure the
homogeneity when filling with wort.
 In the vessel ,wort is inoculated with yeast
and fermentation proceeds for 40 to 48hrs.
 Mixing is achieved by the addition of carbon
dioxide bubbles—rise rapidly in the vessel.
 Temperature control is monitored by
probes positioned at suitable points within
the vessel.
 A no. of cooling jackets are fitted to the wall
to regulate & cause flocculation & settling of
yeast.

14.  The fermentation is terminated by the
circulation of chilled water via cooling jackets
which results in yeast flocculation.
 Thus it is necessary to select yeast stains which
will flocculate readily in the period of chilling.
ADVANTAGES OF THIS VESSEL IN BREWING:
o Reduces process times —increased movement
within the vessels.
o Primary fermentation and conditioning carried
out in same vessel.
o The sedimented yeast—easily removed since
yeast separation is good.
o Maturing time may be reduced by gas washing
with carbon dioxide.

16.  Dawson developed cyclone column fermenter
for the growth of filamentous cultures
 Culture liquid—pumped from bottom to top
of the cyclone column through a closed loop
 Descending liquid ran down the walls of the
column in a relatively thin film
 Nutrients & air—fed near the base, exhaust
gases are left at the top
 Advantages: Good gas exchange, lack of
foaming, limited wall growth

17. PARTS OF CYCLONE –
COLUMN FERMENTER
I – cyclone column
II – circulating pump
III – recirculating limb

18.  It is essentially a gas tight baffled riser tube
connected to the downcomer tube.
 Air or gas mixture—introduced into the base of the
riser by a sparger during normal operating
conditions.
 The driving force for circulation of medium in vessel
is produced by the differences in density between
the liquid column in the riser and in the down
comer.
 This type of vessel can be used for continuous
culture.
 It would be uneconomical to use a mechanically
stirred fermenter to produce SCP from methanol as a
carbon substrate ;as heat removal would be needed
in external cooling loops because of high rate of
aeration and agitation required to operate this
process.

19.  To overcome these(Use of mechanical
stirrers,cooling) problems air lift fermenters
with outer or inner loops were chosen.
 ICI plc initially used an outer loop system in
their pilot plant—all other companies
preferred an inner loop design for large scale
operation.
 In ICI plc continuous process air and gaseous
ammonia were introduced at the base of the
fermenter.

20.  Sterilized methanol, other nutrients and
recycled spent medium were also introduced
into the down comer.
 Heat from exothermic fermentation—
removed by surrounding part of the
downcomer with cooling jacket in pilot
plant.
 At full scale it was found necessary to insert
cooling coils at the base of the riser.
 Unfortunately the production of SCP for
animal feed was unprofittable because of the
price of methanol etc.

22. TYPES OF ALR:
1- INTERNAL LOOP ALR
2-EXTERNAL LOOP ALR

23.  Design of continuous culture fermenter—
necessary mechanical power input with a pump
to circulate the liquid medium –gas entrainer
 Two construction—gas entrainer nozzles
 Injector
 Ejector
 Injector—jet of medium—surrounded by a jet
compressed air
 Gas from outlet enters the large tube with the
nozzle velocity 5 to 100m/s
 Expands in tube—form large air bubbles—
dispersed by the shear of water jet

24.  Ejector—liquid jet enters into a large
converging-diverging nozzle—entrains the gas
around the jet
 Gas is sucked into the converging-diverging
jet is dispersed in that zone
 Aerated medium is pumped by a multiphase
pump through a broth cooler to an air
entrainer above the fermenter

25.  Air medium mixture falls down—conical shaft
at high velocity—creates a turbulence in the
fermenter
 2/3rd of the exhaust gas is vented from the
fermenter head space—reminder via
multiphase pump
 Oxygen transfer rate 4.5g/dm3 h with an
energy consumption of 1kW/hkg

27.  Application for the immobilized cells
 A vertical cylindrical column is packed with
pieces of some relatively inert
material(woodshavings, twigs, coke,
polythene)
 Both medium and cells are fed into the top
of the packed bed
 Once cells get adhersed to support(thin
film)—fresh medium added at the top of the
column—fermented medium removed from
the bottom of the column

28.  Vinegar generator—ethanol is oxidised to
acetic acid by strains of acetobacter
 Mainly used for sewage and effluent
treatment
 In treatment with gas liquor a column was
packed with the height—7.9m with Dowpac—
polystrene derivatives

29.  Effluent treatment
 Utilize a growing microbial film on slow
rotating discs to oxidizes the effluent
 ANDERSON and BLAIN—construct small
fermenter(40dm3)
 Range of filamentous fungi—Aspergillus,
Rhizopus, Mucor, Penicillium—grow on
polypropylene discs
 Obtain yield—80g/dm3—production of citric
acid using A.niger

30.  Principles of fermentation technology
Peter F. Stanbury, Allan Whitaker