This document discusses fermentation design and types. It begins by defining fermentation as the process of growing microorganisms in a nutrient media to produce desired end products like food, alcohol, and pharmaceuticals. There are two main types of fermentation - surface fermentation using tray or packed bed fermenters, and submerged fermentation using stirred tank, airlift, or bubble column fermenters. The document outlines the design considerations for fermenters including maintaining favorable growth conditions and ends by comparing batch and continuous fermentation processes.

1. FERMENTATION-
DESIGN & TYPES
Mr. Dilip O. Morani.
Asst. Prof.,
Shri D. D. Vispute College of Pharmacy
and Research Center, Panvel.

2. FERMENTATION
 Fermentation is the process of growing
microorganisms in a nutrient media by
maintaining physico- chemical
conditions and thereby converting feed
into a desired end product
 Fermentation technology is the use of
organisms to
pharmaceuticals
produce
and
food,
alcoholic
beverages on a large scale industrial
basis.

3. MAJOR FERMENTATION PRODUCTS
Group Product Organism
Industrial
chemicals
Ethanol
Lactic acid
Saccharomyces cerevisiae
Lactobacillus bulgaricus
Enzymes -amylase
Proteases
Lipases
Bacillus subtilis
Bacillus species
Saccharomyces lipolytica
Antibiotics Penicillin
Streptomycin
Chlorampenicol
Penicillium chrysogenum
Streptomyces griseus
Streptomyces venezuelae
Vitamins Riboflavin
Vitamin B12
Ashbya gossypi
Pseudomonas dentrificians

4. DESIGN OF FERMENTER A fermentation process requires a fermenter for successful production
.
 Fermentor is the large vessel containing considerable quantities of
nutrient media by maintaining favourable conditions.
 The design and nature of the fermentor varies depending upon the
type of fermentation carried out. Invariably all the fermentors provide
the following facilities for the process such as
 contamination free environment,
 specific temperature maintenance,
 maintenance of agitation and aeration, pH control,
 monitoring Dissolved Oxygen (DO),
 ports for nutrient and reagent feeding (antifoam agents, alkali or
acid),
 ports for inoculation and sampling,
 provide all aseptic conditions at the time of sample withdrawal
and addition of innoculum
 complete removal of broth from the tank and should be easy to
clean
 It should be designed in such away that it consumes less power,
have less evaporation, can be used for long periods of operation

5. FigI. An Ideal fermenter
DESIGN OF FERMENTER

6. TYPES OF FERMENTER
Available in various sizes
According to the sizes classified as
 Small lab and research fermenter :1-50L
 Pilot plant fermenter: 50-1000 L
 Large size industrial production scale fermenter: more than 1000 L
 Broadly fermentes are also claified as
I. surface fermenters
 Tray fermenter
 Packed bed column fermenter
II. Submerged fermenters
 Simple fermenters (batch and continuous)
 Fed batch fermenter
 Air-lift
 Bubble fermenter
 Cyclone column fermenter
 Tower fermenter
 Other more advanced systems, etc

7. TYPES OF FERMENTER
Surface fermenters
 Microbial cells cultured on surface layer of
the nutrient medium (solid/liquid) held in dish
or tray
Aspergillus niger and nicotinic
 Used for production of citric acid
acid
from
from
Aspergillus terrus
 Microbial films can be developed on the
surfaces of suitable packing medium, may be
in the form of fixed bed, stones or plastic
sheets

8. TRAY FERMENTER
 TRAY FERMENTER
 one of the simplest and widely used fermenters.
 Its basic part is a wooden, metal, or plastic tray, often with
a perforated or wire mesh bottom to improve air circulation.
 A shallow layer of less than 0.15 m deep, pretreated
substrate is placed on the tray for fermentation.
 Temperature and humidity-controlled chambers are used
for keeping the individual trays or stacks.
 A spacing of at least one tray height is usually allowed
between stacked trays.
 Cheesecloth may be used to cover the trays to reduce
contamination.
 Inoculation and occasional mixing are done manually,
often by hand.

9. TRAY
FERMENTER
•Solid as well as liquid
medium are used
•If liquid medium, cells are
allowed to float easily and to
make a process continuous
•If solid medium is used the
micro-organisms are
allowed grow on moist solid
materials, process is called
Solid State Fermentation

10. SOLID STATE FERMENTATION (SSF)
Solid State Fermentation Method (SSF)
 SSF defined as the growth of the micro-organisms on
(moist) solid material in the absence or near-absence
of free water
 Used for production of antibiotics, enzymes, alkaloids,
organic acids bio-pharmaceutical products
yields than submerged liquid
Advantages :
• Produce higher
fermentation
• Possibilities of contamination by bacteria and yeast
is very less
• All natural habitats of fungi are easily maintained in
SSF
• culture media very simple , provides all nutrients for
growth of micro-organisms

11. SSF
Disadvantages:
•Causes problems in monitoring of the process parameters such
as pH, moisture content, and oxygen concentration
•Despite some automation, tray fermenters are
labor intensive
•Difficulties with processing hundreds of trays limit their
scalability
•Aeration may be difficult due to high level of solid content
•Substrates require pre treatment such as size reduction,
chemical or enzymatic hydrolyses

12. SUBMERGED FERMENTERS
The microorganisms are dispersed in liquid
nutrient medium at maintained environmental
conditions.
on the mechanism of agitation Submerged
fermenters grouped as follows:
I. Mechanically stirred fermenter
○ batch operate fermenter
○ continuous stirred tank fermenter
II. Forced convection fermenters
○ Air –lift fermenter
○ Bubble column
○ Sparged tank fermenter
III. Pneumatic fermenter
○ Fluidized bed reactor

13.  These are equipped with a
mechanical agitator so as to maintain
homogencity and rapid dispersion
and mixing of materials
stirred tank Examples includes
fermenter (batch or continuous
operated) , multistage fermenter,
paddle wheel reactor, and stirred loop
reactor
MECHANICALLY STIRRED
FERMENTER

14. STIRRED TANK
FERMENTER (STF)
stirred tank fermenter
 batch operated
fermenter
 agitators consists of one
or more impellers
mounted on the shaft
 It is rotates with the help
of electric motor
of this
flexibility in
 Advantage
fermenter
design
 Used in the range of 1-
100 ton capacity sizes Stirred tank fermenter

15.  A continuous stirred
tank fermenter consists
of a cylindrical vessel
with motor driven
central shaft that
supports one or more
agitators (impellers).
 The shaft is fitted at
the top of the
bioreactor (ref. fig.).
The number of
impellers is variable
and depends on the
size of the fermenter
CONTINUOUS STIRRED TANK
FERMENTER (CSTF)
Continuous stirred tank
fermenter

16. CONTINUOUS
STIRRED TANK
FERMENTER
 In this fresh medium is added continuously in
the fermenter vessel
 On the other end the medium is withdrawn for
the recovery of fermentation products
 As it is a continuous fermenter the Steady state
conditions can be achieved by either
Chemostatic or Turbidostatic principles.

17. CONTINUOUS STIRRED
TANK FERMENTER(CSTF)
 Different types of continuous fermenter
are
a.Single stage: single fermenter is
inoculated and kept in continuous
operation by balancing the input and
output culture media
b. Recycle continuous fermentation: a
residual unused substrate plus
portion of the withdrawn culture or
the
withdrawn culture is recycled

18. CSTF
c. Multistage
continuous
operation: involves
two
or more stages
with
the fermenter
being operated
in sequence
multistage

19. STF
Advantages of batch operated
 Less risk of contamination because of short
growth period
 Process is more economical and simple
 Raw material conversion level is high
Disadvantages:
 Low productivity due to time required fro
the sterilizing, filling, cooling, emptying and
cleaning
subcultures for inoculation, labor
 More expenses are required for
and
process control

20. STF
Advantages of continuous operated
 Less labor expenses due to automation of
fermentation process
 Less toxicity risk to operator by toxins producing
microorganisms
 High yield and good quality product due invariable
operating parameters and automation of the
process
 Less stress on the fermenter as sterilization is not
frequent
Disadvantages:
 Higher investment costs in control and automation
equipment
 More risk of contamination and cell mutation

21. AIR LIFT
FERMENTER
 Airlift fermenter (ALF) is generally
classified as forced convection
fermenters without any mechanical
stirring arrangements for mixing.
 The turbulence caused by the fluid
(air/gas) flow ensures adequate
mixing of the liquid. The baffle or
draft tube is provided in the reactor.
 A baffle or draft tube divides the
fluid volume of the vessel into 2
inter-connected zones.
 Only one of the 2 zones is sparged
with air or other gas.
 The sparged zone is known as "
riser", the zone that receives no gas
is "downcomer“.
Air lift fermenter

22. AIR LIFT
FERMENTER
 Mainly 2 types
 Internal-loop airlift bioreactor (ref
Fig) has a single container with a
central draft tube that creates
interior liquid circulation channels.
These bioreactors are simple in
design, with volume and circulation
at a fixed rate for fermentation.
 External loop airlift bioreactor (ref
fig) possesses an external loop so
that the liquid circulates
through
independent
separate
channels.
These reactors can be
suitably modified to suit the
requirements of different
fermentations.
Internal loop External loop

23. AIR LIFT
FERMENTER
Advantages
 The airlift bioreactors are more efficient than
bubble columns, particularly for more denser
suspensions of microorganisms as the mixing of
the contents is better compared to bubble
columns.
 Commonly employed for aerobic bioprocessing
technology.
 They ensure a controlled liquid flow in a recycle
system by pumping.
 Due to high efficiency, airlift bioreactors are
sometimes preferred e.g., methanol production,
waste water treatment, single-cell protein
production

24.  There are two different process of
fermentation viz.:
 (1) Batch fermentation
 (2) Continuous culture.
Batch fermentation:
 Nutrients are added in the fermentation for
the single time only and growth continues
until the particular nutrients are exhausted

25.  In the batch process when the microorganism is
added into a medium which supports its growth,
the culture passes through number of stages
known as ‘growth curve’
A typical growth curve consists of following stages
a) Lag phase
b) Acceleration phase
c) Log or exponential phase
d) Deceleration phase
e) Stationary phase
f) Death phase

26.  (a) Lag phase:
 Immediately after inoculation, there is no increase
in the numbers of the microbial cells for some time
and this period is called lag phase. In this is phase
the organisms adjust to the new environment in
which it is inoculated into.
 (b) Acceleration phase:
 The period when the cells just start increasing in
numbers is known as acceleration phase.
 (c) Log phase:
 This is the time period when the cell numbers
steadily increase.
 (d) Deceleration phase:
 The duration when the steady growth declines.

27.  (e) Stationary phase:
 The period where there is no change in the
microbial cell number is the stationary phase. This
phase is attained due to depletion of carbon source
or accumulation of the end products.
 (f) Death phase:
 The period in which the cell numbers decrease
steadily is the death phase. This is due to death of
the cells because of cessation of metabolic activity
and depletion of energy resources.
 Depending upon the product required the different
phases of the cell growth are maintained. For
microbial mass the log phase is preferred. For
production of secondary metabolites i.e. antibiotics,
the stationary phase is preferred.

28. GROWTH KINETICS OF BATCH
CULTURE
The number of living cells (population of growth rate
dN/dt)varies with time in a batch system as shown
below:

29. where;
LAG PHASE:
NUMBER OF BACTERIA DOES NOT CHANGE WITH TIME IN
LAG PHASE.
LOG Phase:
Number of bacteria increases exponentially in log phase.

30. DURING LOG PHASE THE
NUMBER OF ORGANISMS IN
THE REACTOR AT ANY
TIME T CAN BE
CALCULATED, BY USING
RATE EQUATION SHOWNbelow:

31. According to last equation, number of bacteria in the
reactor at any time t during log phase can be calculated,
as it is seen in the graph.
THIS RATE EQUATION CAN BE
INTEGRATED:

32. STATIONARY PHASE:
There is no net change in number of bacteria with time
in stationary phase. Bacteria divide but also die at
equal rate. Most of the important biological products
(especially secondary metabolites like antibiotics) or
biomass are produced during this phase.
The biomass concentration at stationary phase is
determined by following equation
X = Y. SR
X=cell concentration
Y= yield factor for limiting nutrient
SR = original nutrient concentration in the medium

33.  Y’ measures the efficiency of a cell in
converting nutrients into biomass
 So the biomass at a particular time in the
during the fermentation is given by the
following equation.
X = Y (SR -s)
S= nutrient concentration at particular time
thus ‘Y’ is represented by the following equation
Y = X/ (SR - s)

34. CONTINUOUS OPERATIONS
Continuous fermentation:
 The growth rate and physiological conditions of
microorganisms can be maintained by using a
process of continuous culture (chemostat )
 In this the products are removed continuously
along with the cells and the same is
replenished with the cell girth and addition of
fresh culture media. This results in a steady or
constant volume of the contents of the
fermenter. This type of fermentation is used for
the production of single cell protein (S.S.P),
antibiotics and organic solvents.

35. CONTINUOUS FERMENTATION
PROCESS
 The dilution rate is the ratio of inflowing
amount of medium to the volume of the
culture.
 Thus
 D = F / V
D= dilution rate
F= Flow rate
V=Volume

36.  The change in cell concentration of cells at
perticular time period is expressed by the
following equation
dx/dt= growth rate – output
Or dx/dt = μx - Dx
In the process of continuous culture technique
the output is balanced by growth hence,
μx = Dx
μ – D
Dx / dt= D

37.  The biomass concentration in the
chemostat is determined by the
following equation
X = Y(SR - s)
X= steady state concentration
S= steady state residual concentration in
the medium

38. ADVANTAGES AND DISADVANTAGES OF BATCH AND
CONTINUOUS OPERATIONS
BATCH SYSTEMS
 easy to operate and control
 genetic stability of organism
could be controlled if it is
genetically engineered
biocatalyst.
 lower contamination risk
 non-productive down time is a
disadvantage
 batch to batch variability is
problem
 accumulation of inhibitory
products is problem
CONTINUOUS SYSTEMS
 degeneration of
biocatalyst
 higher contamination risk
is a disadvantage
 efficient, higher
productivity
 product is obtained with
uniform characteristics;
quality of the product is
almost same from time to
time
 no accumulation of
inhibitory products.