Bioreactors used for industrial fermentations

1. PRESENTED BY:
Gurpreet Kaur
L-2011-BS-239-M
INDUSTRIAL BIOREACTORS
DESIGN AND FUNCTIONAL
CHARACTERISTICS

2. BIOREACTOR
 Vessel for the growth of microorganisms
which, while not permitting contamination,
enables the provision of conditions necessary
for the maximal production of the desired
products.

3. FERMENTATION
 Fermentation processes utilize microorganisms to
convert solid or liquid substrates into various
products.
 Commonly consumed fermented products include
bread, cheese, beer, wine, citric acid, vinegar etc.
• Submerged culture citric acid production by
Aspergillus niger
• Solid state koji fermenation
AEROBIC
FERMENTATION
• Submerged culture yoghurt production by
Streptococcus thermophilus and
Lactobacillus bulgaris.
• Solid state anaerobic fermentation by acid
forming
bacteria, particularly, Lactobacillus, Pediococ
cus, Micrococcus sp. produce fermented
meat products like pepperoni .
ANAEROBIC
FERMENTATION

4. • A batch of culture medium in a bioreactor is
inoculated with starter culture.
• Fermentation proceeds for a certain duration
and the product is harvested.
BATCH
FERMENTATION
• Sterile culture medium is added periodically to
the inoculated fermentation broth.
• Bioreactor is harvested after the batch time.
FED BATCH
FERMENTATION
• Sterile medium is fed continuously into
bioreactor.
• Fermented product is continuously drawn.
CONTINUOUS
FERMENTATION

5. SUBMERGED
FERMENTATION
• Utilizes free flowing
liquid
substrates, such as
molasses and
broths.
• Substrates are
utilized quite
rapidly, need to be
replaced constantly.
• Best suited for
bacteria that require
high moisture
content.
SOLID-STATE
FERMENTATION
• Utilizes solid
substrates like bran,
bagasse and paper
pulp.
• Substrates are
utilized very slowly,
need not to be
replaced.
• Best suited for fungi
that require less
moisture content.

6. ASEPTIC OPERATION AND CONTAINMENT
ASEPTIC OPERATION
• Protection against contamination
CONTAINMENT
• Prevention of escape of viable cells from the
bioreactor.
o Bioreactor must be sterilized prior to operation.
o Sterile air must be introduced into bioreactor.
o Inoculation and sampling must be done under
aseptic conditions.
o Ports and nozzles must be sealed properly.

7. BIOREACTOR
S
SUBMERGED
CULTURE
BIOREACTORS
STIRRED TANK
BIOREACTOR
AIRLIFT BIOREACTOR
BUBBLE COLUMN
BIOREACTOR
SOLID STATE
BIOREACTORS
TRAY BIOREACTOR
PACKED BED
BIOREACTOR
ROTATING DRUM
BIOREACTOR
AGITATED AND
FORCEFULLY AERATED
BIOREACTOR

8. STIRRED TANK BIOREACTOR

11. VESSEL
• MATERIALS OF
CONSTRUCTION
AERATIO
N AND
AGITATIO
N
• AGITATOR
(IMPELLER)
• BAFFLES
• AERATION SYSTEM
(SPARGER)
CONTROL
AND
MONITORIN
G
(PROBES)
• TEMPERATURE
• DISSOLVED OXYGEN
• pH
• PRESSURE
• FOAM
DESIGN

12. VESSEL: MATERIALS OF CONSTRUCTION
 Industrial scale vessels are constructed of
stainless steel: SS304, SS304L, SS316, SS316L
 SS304: lower value, unlicensed products.
 SS316L: high value, licensed products.
 AISI grade 316 steels which contain 18%
chromium, 10% nickel and 2.5% molybdenum are
commonly used for industrial operations.
 AISI grade 317 (stainless steel with 3-4%
molybdenum) is used in citric acid fermentation
(pH 1-2) to prevent leaching of heavy metals from
the steel which would interfere with fermentation.
 AISI grade 304 (18.5% chromium & 10% nickel) is
used for brewery equipment.

13. AERATION AND AGITATION
AERATION
• Provide sufficient oxygen for metabolic requirements of
microorganisms
AGITATION
• Make uniform suspension of microbial cells in homogeneous
nutrient medium.
AGITATOR (IMPELLER)
BAFFLES
AERATION SYSTEM (SPARGER)

14. AGITATOR (IMPELLER)
 Mounted on the shaft at a specific distance off the
tank bottom
 Bulk fluid and gas phase mixing
 Oxygen transfer
 Heat transfer
 Suspension of solid particles
 Maintain a uniform environment throughout the
vessel contents
Rushton turbine of 1/3rd the
bioreactor diameter is considered
the optimum design for use in
many fermentation processes.

15. SCABA
6SRGT
• Handle high air
flow rate
• Radial flow
agitator
• Better for bulk
blending than
rushton turbine
PROCHEM
MAXFLO
• 4,5 or 6 hydrofoil
blades set at a
critical angle on a
central hollow
hub
• Agitator to vessel
ratio is greater
than 0.4
• Maximum power
requirement is
66% of that with
rushton turbine.
EKATO
INTERMIG
• More complex in
design
• Agitator to vessel
diameter ratio is
0.6-0.7
• Less loss in
power than with
rushton turbine

16. BAFFLES
 To minimize fluid
swirling and vortex
formation
 Metal strips roughly
1/10th vessel diameter
and attached radially
to the wall
 6-8 baffles are used
in industrial scale
bioreactors.
 Baffling tends to
increase transmittable
power, to improve
mixing and aeration

17. AERATION SYSTEM (SPARGER)
POROUS SPARGER
• Produce small bubble size, difficult to clean
ORIFICE SPARGER
• Perforated pipe arranged below impeller in the form of rings
NOZZLE SPARGER
• Single open or partially closed pipe, does not get blocked
COMBINED SPARGER AGITATOR
• Air introduced via hollow shaft and emitted through holes drilled in the disk
blades
DYNAMIC SPARGER
• Gas pumped through porous metal tube directed into pipeline, one of the
cheapest and most efficient sparger
INTRUSIVE SPARGER
• Sparger element located in pipeline

18. CONTROL AND MONITORING
 Allows better process modelling and closer process
control.
 Highly selective in-situ methods are developed for
process monitoring.
 An essential development in process analysis in
bioreactor is the development of miniaturized sensors
for in-situ measurement of pH, dissolved oxygen (DO),
foam etc.
PARAMETERS MONITORED AND
CONTROLLED IN BIOREACTORS
 TEMPERATURE
 DISSOLVED OXYGEN
 PRESSURE
 pH
 FOAM

19. TEMPERATURE
 Cultivation temperature is normally
monitored with an accuracy of not less
than ±0.5˚C.
 Stainless steel Pt100 sensors are
used
 Other temperature measurement
devices:
GLASS THERMOMETERS
BIMETALLIC THERMOMETERS
PRESSURE BULB THERMOMETERS
THERMOCOUPLES
METAL RESISTANT THERMOMETERS (THERMISTORS)

20. TEMPERATURE CONTROL
Water jackets or pipe coils within the bioreactor
are used as means of temperature control.
Temperature is measured by the sensor and
signal is sent to temperature controller
The set point is entered in the controller which
is compared with the measured value
Either heating or cooling finger of bioreactor is
activated to slowly decrease the error and
bring the measured value close to set point

21. DISSOLVED OXYGEN
 Measured by DO probe.
 DO electrodes measure partial pressure of dissolved oxygen.
 In the event of low oxygen tension in broth, more oxygen is
purged in bioreactor and/or agitator speed is increased.
 Polarographic electrodes
 Phase fluorometric oxygen sensor
pH
 Only sterilizable electrodes are used.
 Combined glass reference electrode: silver/silver chloride
electrodes with KCl as electrolyte.
 The control of pH values is ensured with the help of peristaltic
pumps, correspondingly metering out acid/alkali.

22. 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 valves
controlled by associated pressure gauges.

23. FOAM
 The appearance 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.
 ELIMINATION OF FOAM:
 Additional metering of antifoam based on sensor:
 Probe is inserted through top of bioreactor: stainless
steel rod set at a defined level above the broth surface.
 When foam rises and touches the probe tip, pump is
activated and antifoam is released into bioreactor.
 Mechanical metering of foam:
 Mechanical antifoam devices: discs, propellers, brushes
or hollow cones attached to agitator shaft above the broth
surface.
 Foam is broken down when it is thrown against the walls
of the bioreactor.

24. Category Example Chemical
nature
Remarks
Silicones Antifoam A (dow
corning ltd.)
Polymers of
polydimethyl-
siloxane fluids
Very active, inert,
highly dispersable,
low toxicity,
expensive
Polyethers P400, P1200, P2000
(dow chemical co.)
Polymers of ethylene
oxide & propylene
oxide
Active, but varies
with fermentation
Natural oils and fats Peanut oil, soyabean
oil
Esters of glycerol
and long chain
mono-basic acids
Not very efficient,
used as carriers for
other antifoams, may
be metabolized
Alcohols Sorbitan alcohol Mainly alcohols with
8-12 carbon atoms
Not very efficient,
may be toxic or
maybe metabolized

25. PRODUCT MICROORGANI
SM
BIOREACTO
R VOLUME
(Litres)
REFERENCE
Organic acids Escherichia coli 22000 Enfors et al, 2001
Glutamic acid Corynebacterium
glutamicum
24000 Hermann, 2003
Lysine Corynebacterium
glutamicum
10000 Pfefferle et al,
2003
Xanthan Xanthomonas
campestris
3000 Herbot, 2004
Ethanol Kluyveromyces
marxianus
1200 Singh et al, 2002
REPORTS ON THE INDUSTRIAL USE OF
STIRRED TANK BIOREACTOR

26. AIRLIFT
BIOREACTOR
o The content is agitated by
a stream of air.
o Gas stream facilitates
exchange of material
between gas phase and
the medium
o Oxygen is transferred to
liquid and reaction
products are removed
through exchange with
gas phase.

27. SECTIONS OF AIRLIFT BIOREACTOR
4 sections with different flow
characteristics
 RISER: the gas is injected
at bottom of this section and
flow of gas and liquid is
upward.
 DOWNCOMER: this section
is connected to riser at
bottom and top. The flow of
gas and liquid is downward.
 BASE: the bottom
connection zone between
riser and downcomer is
base.
 GAS SEPARATER: this
section at the top of
bioreactor connects riser to
downcomer, facilitating
liquid recirculation.

29. COMPARISON WITH STIRRED
TANK BIOREACTORS
 Higher efficiency in mass transfer
 Easy to scale-up
 Require less energy to operate
 As stirred tank bioreactors grow in size, their
mixing quality suffers. On the other hand, the
mixing time is not compromised with airlift
bioreactors.

30. COMMERCIAL AIRLIFT
BIOREACTOR DESIGNS USED IN
INDUSTRIES
CONCENTRIC
DRAFT TUBE
AIRLIFT
BIOREACTOR
TOWER
LOOP AIRLIFT
BIOREACTOR

31. CONCENTRIC DRAFT TUBE AIRLIFT
BIOREACTOR
 Most industrial airlift
bioreactors are of this type.
 Draft tube functions as
aerated section
 Air sparged liquid rises up
the draft tube, is partially
degassed and flows down
the annulus.

32. TOWER LOOP AIRLIFT
BIOREACTOR
 Air sparger riser column
physically separated from
downcomer.
 2 vertical columns of
different diameters
connected at the top with
degassing zone and at
bottom with liquid return line.
 Luttmann et al (1982)
developed a steady state
model for mass production
of bacteria and yeast.

33. CASE STUDY
 Chang (2010) investigated the production of
ethanol by Antrodia cinnamomea in 500L
airlift bioreactor. 17µg/ml ethanol extracts
were produced after 28 days of cultivation.
 Liu et al (2003) studied the production
chitinase by Verticillum lecanii in 600 L airlift
bioreactor. At the aeration rate of
0.9vvm, 19.9mU/ml chitinase activity was
observed.

34. BUBBLE COLUMN BIOREACTOR
 Gas in the form of
bubbles come in
contact with liquid.
Purpose is mixing
the liquid and
transfer of
substances from
one phase to other.
 Cylindrical vessel
with gas distributor
at bottom.
 Gas is fed into the
column at the
bottom and rises in
the liquid, escaping
from it at the upper
surface.

35. REPORTS ON INDUSTRIAL USE OF
BUBBLE COLUMN BIOREACTORS
PRODUCT MICROORGANISM REFERENCE
Ethanol fermentation Saccharomyces
cerevisiae
Ogbonna et al, 2001
Organic acids
(acetic, butyric acid)
Eubacterium limosum Chang et al, 2001
Thienamycin Streptomyces cattleya Arcuri et al, 2002
Acetic acid Acetobacter aceti Sun et al, 1998
Glucoamylase Aureobasidium
pullulans
Federici et al, 2000

36. SOLID STATE BIOREACTORS
 Simple technology
 Product yields are usually higher
 Lower chance of contamination due to low moisture levels
 Easy product separation
 Oxygen is typically freely available at the surface of the particles.
 Energy efficiency
 Resembles natural environment for microorganisms.
 Use of waste materials as substrates
 No foam generation
 Lower capital operating costs
SOLID STATE
BIOREACTO
RS
TRAY
BIOREACTOR
PACKED BED
BIOREACTOR
ROTATING
DRUM
BIOREACTOR
AGITATED AND
FORCEFULLY
AERATED
BIOREACTOR

37. TRAY BIOREACTOR

38.  The top of tray is opened and bottom & sides
may be perforated for aeration.
 Temperature is regulated by circulating
warm/cool water as required.
 Relative humidity is controlled by passing
saturated or dry air through the chamber.
 Height of substrate in tray ranges from 5-15
cm.
 Scale up is achieved by increasing the area
and number of trays.
 Large scale processes use a large number of
trays of same size that are used in laboratory.

39. PACKED BED BIOREACTORS
 Operated under conditions of forced aeration,
in which air is blown through a sieve, but the
substrate bed is not mixed.

40.  On the basis of heat removal considerations, the column may
be covered with water jacket that would be called a
TRADITIONAL PACKED BED BIOREACTOR, or use heat
transfer plate inserted into the bed, which is called ZYMOTIS
PACKED BED BIOREACTOR.
 In traditional packed bed bioreactors, there is a problem of
heat removal.

41. ZYMOTIS PACKED BED BIOREACTOR
 Best suited for
industrial operations.
 Packed bed
bioreactors with
internal cooling plates
for heat transfer.
 Small spacings
between plates are
used in order to
achieve high
productivity
 Cooling water is
varied during
fermentation in
response to bed
temperature

42. CASE STUDY
 Roussos et al (1993) studied the design and
evaluation of zymotis bioreactor at different
capacities for cellulase production by
Trichoderma harzianum , which gave similar
performance as in the parallel fermentation
under optimized parameters in column
fermenter of high efficiency.
CAPACITY (kg) CELLULASE
PRODUCTION IN
ZYMOTIS (IU/g)
CELLULASE
PRODUCTION IN
COLUMN (IU/g)
4 133.54 131.36
8 135.26 131.64
10 128.03 125.81
12 74.16 71.85

43. ROTATING DRUM BIOREACTOR
 Bed of bioreactor is mixed either continuously
or intermittently and air is circulated through
head space of the bed.

44.  Consist of a cylindrical drum
lying horizontally
 Drum is partially filled with a
bed of substrate and air is
blown through headspace.
 The drum rotates around the
central axis to mix the bed.
 Intermittent mixing bioreactor
operates like a tray
bioreactor during static
period and like a continuous
rotating bioreactor during
period of rotation.
 It is necessary to limit the
height of substrate bed in
order to achieve good O₂ and
CO₂
 Might include the use of baffles

45. CASE STUDY
 Kaloris et al (2003) studied the production of
cellulases and hemicellulases by
Thermoascus aurantiacus in an intermittent
agitation rotating drum bioreactor. The effect
of initial moisture content, temperature and
airflow were studied to find the optimum
conditions for industrial production.
 Mitchell et al (2002) studied the growth of
Aspergillus oryzae in rotating drum bioreactor.
It was found that the initial velocity of rotation
needed for 24L bioreactor is 0.0023m/s and
for 2200L bioreactor is 0.4m/s.

46. AGITATED AND FORCEFULLY
AERATED BIOREACTORS
 The bed of bioreactors is agitated and air is
blown forcefully through the bed
 Combination of agitation and forced aeration
helps in avoiding temperature and moisture
gradients in the bed.
CONTINUOUS MIXING, FORCEFULLY
AERATED BIOREACTORS
INTERMITTENT MIXING, FORCEFULLY
AERATED BIOREACTORS

47. CONTINUOUS
MIXING, FORCEFULL
Y AERATED
BIOREACTORS
CONTINUOUSLY
STIRRED AERATED
BED
ROCKING DRUM
BIOREACTOR
GAS-SOLID
FLUIDIZED BED

48. CONTINUOUSLY STIRRED
AERATED BED:
 Used for ethanol production
 Not used for fungi because of
damage due to continuous
mixing.
GAS-SOLID FLUIDIZED BED:
 Gas is blown upwards
through perforated base
plate to fluidize the substrate
bed.
 The gas flow rate is high
enough to give good heat
and mass transfer between
the substrate particles and
gas-phase.

49. ROCKING DRUM BIOREACTOR
 Consist of substrate held between two perforated
drums encased in an unperforated outer
bioreactor shell.
 The outer two drums are rotated backwards and
forth in relation to the inner drum at 0.2 rpm.

50. INTERMITTENT MIXING, FORCEFULLY
AERATED BIOREACTOR
 Similar to packed bed, except that the bed contains
an agitator.
 INRA STIRRED BED DESIGN: large scale
intermittent mixing, forcefully aerated bioreactor.
 Agitators are mounted across the width on a movable
trolley, which moves up and down the bioreactor.
 The speed of movement of trolley affects the intensity
of mixing.
 Used for enzyme production and biopesticide
production on large scale.

51. REPORTS OF THE USE OF VARIOUS SOLID STATE
BIOREACTORS
Bioreactor Key processes and bioreactor features Reference
Tray Alkaline protease production by Aspergillus flavus on 30 kg steamed
wheat bran in perforated steel trays in koji room
Malathi et al,
2001
Zymotis
packed-bed
Cellulase production by Trichoderma harzianum on 40 kg sugarcane
bagasse and wheat bran mixture
Roussos et al,
2003
Continuously
rotated drum
Kinetic study with Rhizopus oligosporus on steamed wheat bran, in a
stainless steel rotating drum with detectable baffles
Fung and
Mitchell, 2005
Intermittently
mixed aerated
bed
Protein enrichment by Aspergillus tamari on 25 ton moist sugar beet
pulp in a 50 m3 stirred packed-bed
Xue et al, 2002
Continuously
mixed bed
Ethanol production by Saccharomyces cerevisiae on cooked corn grits in
a continuously stirred bioreactor
Sato et al, 2008
Air-solid
fluidized bed
Enzyme production by Aspergillus sojae on 500 kg dry wheat bran in an
8 m3 bioreactor.
Matsuno et al,
2003

52. PLAFRACTOR™
 The bioreactor is modular in nature
and carries out all the processes of
fermentation in a single contained
environment.
 Constructed by stacking individual
modules and the base contains
multiple channels to deliver fluids
into modules and to extract
products from modules.
 The interior of each module has a
mixing arm that revolves around
central axis of module.
Mycophenolic acid: Penicillium
arenicola
Cyclosporin A: Fusarium
solani

53. CONCLUSION
 Bioreactors, the core of bioprocess, are of
submerged and solid-state type.
 In submerged type, stirred tank bioreactors are
the most commonly used in fermentation
industries.
 Solid-state bioreactors have gained wider
attention from industries due to simple
technology and higher yields.
 The parameters controlling the fermentation are
strictly monitored in all the bioreactor designs in
order to ensure maximum productivity.