Bireactors

1. Assignment on Bioreactors
Submitted by:
Awais Ali: BSBTL-13-005
Asad Razzaq: BSBTL-13 -021
M. Aqil Yaqoob: BSBTL-13- 026
Rizwan Abbas: BSBTL-13 -027
Tooba Shehzad: BSBTL-13 -028
M. Ahmad Parvez: BSBTL-13 -029
Anum Munir: BSBTL-13 -033
Course: Environmental Biotechnology
Course no: BSBT-404
Instructor: Dr. Sumaira Rasul
Date of Submission: 22th
November 2017
Schematic diagram of bioreactor
(Fermenter)

2. Bioreactors
Table of Contents
Introduction:...................................................................................................................................................... 3
Examples of Bioreactors ................................................................................................................................ 3
Design of bioreactor: ......................................................................................................................................... 3
Principle and mode of bioreactors...................................................................................................................... 5
Batch reactor: .................................................................................................................................................... 5
Fed batch:.......................................................................................................................................................... 5
Continuous flow reactor:................................................................................................................................ 5
Types of Bioreactors.......................................................................................................................................... 5
Continuous Stirred Tank Bioreactors:............................................................................................................. 5
Bubble Column Bioreactors: .......................................................................................................................... 6
Airlift Bioreactors: ......................................................................................................................................... 6
Two-stage airlift bioreactors:...................................................................................................................... 6
Tower bioreactors: ......................................................................................................................................... 7
Fluidized Bed Bioreactors:............................................................................................................................. 7
Packed Bed Bioreactors: ................................................................................................................................ 7
Photo-Bioreactors: ......................................................................................................................................... 7
Analysis of Bioreactors...................................................................................................................................... 8
Analysis of Measureable parameters .............................................................................................................. 8
Analysis of products .......................................................................................................................................... 8
Application of Bioreactors................................................................................................................................. 9
References....................................................................................................................................................... 10

3. Bioreactors
Introduction:
Definition
A bioreactor is a device or a vessel in which a chemical process is carried out which involves organisms or
biochemically active substances derived from such organisms. This process can either be aerobic (require
oxygen) or anaerobic (in the absence of oxygen).
Size and Structure
These are cylindrical vessels manufacturing by stainless steel. The sizes of the bioreactor can vary over several
orders of magnitudes. The microbial cell culture (few mm3), shake flask (100 -1000 ml), laboratory fermenter
( 1 – 50 L), pilot scale (0.3 – 10 m3) to plant scale( 2 – 500 m3) are all examples of bioreactors.
Why we use Bioreactors
Bioreactors differ from conventional chemical reactors, these are more efficient and applicable they provide
support and control biological entities. These systems provide higher degree of controls over process upsets and
contaminants. These provide a maintain conditions (temperature, pH, amount of oxygen etc.) in which an
organism can comfortably produce a desire product.
In bioreactors higher selectivity present, systems have capability for producing the desired products and play
important role in production of antibiotics, vitamins, proteins, organic acids.
General requirements
 Optimal mixing
 Uniform shearing.
 Adequate mass transfer, oxygen.
 Clearly defined flow conditions.
 Feeding substrate with prevention of under or overdosing.
 Suspensions of solids.
 Gentle heat transfer
Bioreactors yield products, as well as by products and the microbial cell mass. We have to obtain products. The
product formed are then isolated and purified through series of downstream processes. Downstream processes
involve filtration, centrifugation, flocculation, chromatography etc. the products are analyzed or detects by
biosensors, analytical devices etc and quantified.
Examples of Bioreactors
 Laboratory scale bioreactors and processes include: Flask assays, batch fermenter and continues
fermenters.
 Industrial bioreactors include Plug Flow Bioreactors, packed bed Bioreactors, and continuous stirr
tank Bioreactors.
 Nowadays plants and animals are used as Bioreactors in order to produce wide variety and high
quantity production of Biopharmaceuticals. These techniques are known as molecular pharming or
Biopharming using genetic engineering and molecular biological techniques.
Design of bioreactor:
Most fermenters used in industry are of the submerged type (Liquid operated), because the submerged
fermenter saves space and is more agreeable to engineering control and design.
Choice of bioreactors should be made according to these criteria:
 Choose a reactor, which you have experienced before.
 Simple, make no more complications than necessary, because purpose is to lower cost of production.

4.  Main demand is sterile conditions. To maintain sterility, keep valves, pumps, joints, probe insertions,
sample ports, gas inlets as few as possible. Stagnant regions, air pockets, pipe branches, crevices
increase risk of contamination. (Kantarci, Borak, & Ulgen, 2005)
(Nanda, 2008)
The dimension of a bioreactor should comply with design requirements such as sterilization, simple
construction and measuring process control devices, regulating techniques, scale-up, operations, compatibility
with upstream and downstream processes, antifoaming measures etc. are necessary factors .The fundamental
features of a bioreactor include headspace volume, agitator system, oxygen delivery system, foam control,
temperature & pH control system, sampling ports, cleaning and sterilization system and lines for charging &
emptying the reactor.
Headspace volume: The working volume of a bioreactor is the fraction of its total volume taken up by the
medium, microbes, and gas bubbles and remaining volume is called the headspace. Generally, the working
volume will be ~70-80% of the total reactor volume. This, however, rely on the rate of foam formation during
the reactor.
Agitator system: consists of an external power drive, impeller which enhance intense mixing and increased
mass movement rates through thebaffle bulk liquid and bubble boundary layers. It provides enough shear
conditions required for breaking up of bubbles
Air delivery system consists of a compressor, inlet air, sterilization system, air sparger and exit air sterilization
system to avert contamination.
Foam control system is an essential element of bioreactor as excessive liters and builds up pressure infoam
establishment leads to blocked air exit the reactor.
Sampling ports are used to inject nutrients, water, salts etc. in bioreactors and also for collecting samples.
Cleaning and sterilization system is important to avoid contamination.(Singh, Kaushik, Biswas, 2014)
While determining on construction material of bioreactor these properties of material should be taken into
account:
Bioreactor design

5.  mechanical properties
 corrosion resistance
 ease of fabrication
 availability
 cost
Principle and mode of bioreactors
Basic principle of bioreactor is mixing of culture. It includes rotatory motion.
Mode of operation:
 Batch
 Fed batch
 Continuous
Batch reactor:
A batch reactor is used for small-scale operation, for testing new processes that have not been fully developed,
for the manufacture of expensive products, and for processes that are difficult to convert to continuous
operations. he batch reactor has the advantage of high conversions that can be obtained by leaving the reactant
in the reactor for long periods of time, but it also has the disadvantages of high labor costs per batch, the
variability of products from batch to batch, and the difficulty of large-scale production.
Fed batch:
Fed-batch concentration is commonly used to achieve higher volume reduction factors than possible with batch
concentration alone. Instead of returning the retentate back to a feed tank containing the entire batch volume, it
is returned to a smaller retentate tank. Feed is also pumped into this retentate tank at the same rate as permeate
is withdrawn from the system so the retentate tank level remains constant during fed-batch concentration. When
all the feed has been pumped into the retentate tank, one can concentrate the retentate further in a batch
concentration process.
Another way of implementing a fed-batch operation is to put a bypass line in-between the retentate return line
and the pump inlet.
Continuous flow reactor:
Continuous flow reactors are almost always operated at steady state. We will consider three types: the
continuous-stirred tank reactor (CSTR), the plug flow reactor (PFR), and the packed-bed reactor (PBR).
Continuous-Stirred Tank Reactor (CSTR)
A type of reactor used commonly in industrial processing is the stirred tank operated continuously . It is referred
to as the continuous-stirred tank reactor (CSTR) or vat, or back mix reactor, and is used primarily for liquid
phase reactions. It is normally operated at steady state and is assumed to be perfectly mixed; consequently, there
is no time dependence or position dependence of the temperature, concentration, or reaction rate inside the
CSTR.
Types of Bioreactors
Continuous Stirred Tank Bioreactors:
A continuous stirred tank bioreactor consists of a cylindrical vessel with motor driven central shaft that supports
one or more agitators (impellers). The shaft is fitted at the bottom of the bioreactor. The number of impellers is
variable and depends on the size of the bioreactor i.e. height to diameter ratio, referred to as aspect ratio.

6. In stirred tank bioreactors or in short stirred tank reactors (STRs), the air is added to the culture medium under
pressure through a device called sparger. The sparger may be a ring with many holes or a tube with a single
orifice. The sparger along with impellers (agitators) enables better gas distribution system throughout the vessel.
The bubbles generated by sparger are broken down to smaller ones by impellers and dispersed throughout the
medium. This enables the creation of a uniform and homogeneous environment throughout the bioreactor.
There are many advantages of STRs over other types. These include the efficient gas transfer to growing cells,
good mixing of the contents and flexible operating conditions, besides the commercial availability of the
bioreactors.
Bubble Column Bioreactors:
In the bubble column bioreactor, the air or gas is introduced at the base of the column through perforated pipes
or plates, or metal micro porous spargers . The flow rate of the air/gas influences the performance factors —O2
transfer, mixing. The bubble column bioreactors may be fitted with perforated plates to improve performance.
The vessel used for bubble column bioreactors is usually cylindrical with an aspect ratio of 4-6 (i.e., height to
diameter ratio).
Airlift Bioreactors:
In the airlift bioreactors, the medium of the vessel is divided into two interconnected zones by means of a baffle
or draft tube. In one of the two zones referred to a riser, the air/gas is pumped. The other zone that receives no
gas is the down comer. The dispersion flows up the riser zone while the down flow occurs in the down comer.
There are two types of airlift bioreactors.
Internal-loop airlift bioreactor 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 possesses an external loop so that the liquid circulates through separate
independent channels. These reactors can be suitably modified to suit the requirements of different
fermentations. In general, the airlift bioreactors are more efficient than bubble columns, particularly for denser
suspensions of microorganisms. This is mainly because in these bioreactors, the mixing of the contents is better
compared to bubble columns.
Airlift bioreactors are 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. In general, the performance of
the airlift bioreactors is dependent on the pumping (injection) of air and the liquid circulation.
Two-stage airlift bioreactors:
Two-stage airlift bioreactors are used for the temperature dependent formation of products. Growing cells from
one bioreactor (maintained at temperature 30°C) are pumped into another bioreactor (at temperature 42°C).
There is a necessity for the two-stage airlift bioreactor, since it is very difficult to raise the temperature quickly
from 30°C to 42°C in the same vessel. Each one of the bioreactors is fitted with valves and they are connected
by a transfer tube and pump. The cells are grown in the first bioreactor and the bioprocess proper takes place in
the second reactor.

7. Tower bioreactors:
A pressure-cycle fermenter with large dimensions constitutes a tower bioreactor. A high hydrostatic pressure
generated at the bottom of the reactor increases the solubility of O2 in the medium. At the top of the riser, (with
expanded top) reduces pressure and facilitates expulsion of CO2. The medium flows back in the down comer
and completes the cycle. The advantage with tower bioreactor is that it has high aeration capacities without
having moving parts.
Fluidized Bed Bioreactors:
Fluidized bed bioreactor is comparable to bubble column bioreactor except the top position is expanded to
reduce the velocity of the fluid. The design of the fluidized bioreactors (expanded top and narrow reaction
column) is such that the solids are retained in the reactor while the liquid flows out. These bioreactors are
suitable for use to carry out reactions involving fluid suspended biocatalysts such as immobilized enzymes,
immobilized cells, and microbial flocks.
For an efficient operation of fluidized beds, gas is spared to create a suitable gas-liquid-solid fluid bed. It is also
necessary to ensure that the suspended solid particles are not too light or too dense (too light ones may float
whereas to dense ones may settle at the bottom), and they are in a good suspended state. Recycling of the liquid
is important to maintain continuous contact between the reaction contents and biocatalysts. This enables good
efficiency of bioprocessing.
Packed Bed Bioreactors:
A bed of solid particles, with biocatalysts on or within the matrix of solids, packed in a column constitutes a
packed bed bioreactor. The solids used may be porous or non-porous gels, and they may be compressible or
rigid in nature. A nutrient broth flows continuously over the immobilized biocatalyst. The products obtained in
the packed bed bioreactor are released into the fluid and removed. While the flow of the fluid can be upward or
downward, down flow under gravity is preferred.
The concentration of the nutrients (and therefore the products formed) can be increased by increasing the flow
rate of the nutrient broth. Because of poor mixing, it is rather difficult to control the pH of packed bed
bioreactors by the addition of acid or alkali. However, these bioreactors are preferred for bioprocessing
technology involving product-inhibited reactions. The packed bed bioreactors do not allow accumulation of the
products to any significant extent.
Photo-Bioreactors:
These are the bioreactors specialized for fermentation that can be carried out either by exposing to sunlight or
artificial illumination. Since artificial illumination is expensive, only the outdoor photo-bioreactors are
preferred. Certain important compounds are produced by employing photo-bioreactors e.g., p-carotene,
They are made up of glass or more commonly transparent plastic. The array of tubes or flat panels constitutes
light receiving systems (solar receivers). The culture can be circulated through the solar receivers by methods
such as using centrifugal pumps or airlift pumps. It is essential that the cells are in continuous circulation
without forming sediments. Further adequate penetration of sunlight should be maintained. The tubes should
also be cooled to prevent rise in temperature.

8. Analysis of Bioreactors
Bioreactors proceeds biological processes or reactions and in turn yield products, cellular biomass and by
products. During the whole reaction in this systems many factors/parameter are needed to analyze and monitor
in order to achieve better result. Beside the parameter the analysis of reaction and the output (product) is
important to meet the criteria of desired products having required characteristics.
Analysis of Measureable parameters
The control of parameters and components has prime importance for productivity of required product.
 Temperature and measureable factors are kept in control by using Thermistors and analytical devices.
 Fermentation process is enhanced by manipulation of oxygen source accordingly (Supply oxygen in
case of aerobic process and vice versa).
 Optimum growth of microbial source is maintained by providing optimal feed/Substrate concentration.
 In order maintain the equilibrium of reaction Products are preferred to isolate continuously. This favors
the efficiency of reaction.
 By products are sludge are also discard simultaneously to decrease accumulation of wastes.
Analysis of products
The quality and quantity of products are analyzed by different techniques. Generally Quality control is achieved
by monitoring the parameters. Quality of product is analyzed or detected by using analytical devices like
Biosensors, Immobilize enzymes. Quantification is also carried out with the help of physiochemical techniques
and analytical devices. The detected results are generated on Liquid crystal display as measureable signals or
print outs etc.
Quality control
The quality of product is monitored by using immobilized enzymes in the biosensor devices, beside these the
quality production is favored by detecting and manipulating the parameters with the help of sensory devices.
The sensor devices usually detect pH change, temperature gradient, ionic concentration and even mass
alterations.
Quantification
The quantitative analyses are also done with help of analytical devices and other techniques. Color detection,
florescence, ionic quantity, etc reveals the quantity of products yield. Components other than desired products
are also quantified to assume the productivity, which are then reuse if possible or discard.
Downstream processes
Downstream processes are collective techniques used for product recovery and purification purpose. The out
come /out puts are then allow passing through series of downstream processes and converting in to marketable
product. These processes involve, concentration, removal of toxins, Separation/elimination of sludge, drying,
addition of additives and packaging.

9. The analytical or physical procedure in downstream processes are as follows.
 Filtration: Separate insoluble’s from liquid substance
 Flocculation: Aggregates insoluble particles
 Precipitation: collection or aggregation of desired substance.
 Centrifugation: separation of substance according to density.
 Crystallization and drying process for purification purposes.
 Chromatographic techniques are used accordingly to separate and purify the variety of products.
 Modification for preservation and storage and packaging purposes.
Application of Bioreactors
The application of bioreactor culture techniques for plant micropropagation is regarded as one of the ways to
reduce production cost by scaling-up and automation. Recent experiments are restricted to a small number of
species that, however, demonstrate the feasibility of this technology.
Periodic immersion liquid culture using ebb and flood system and column-type bubble bioreactors equipped
with a raft support system to maintain plant tissues at the air and liquid interface were found to be suitable for
micropropagation of plants via the organogenic pathway.
Balloon-type bubble bioreactors proved to be fit for micropropagation via somatic embryogenesis with less
shear stress on cultured cells. Several cultivars of Lilium were successfully propagated using a two-stage culture
method in one bioreactor. A large number of small-scale segments were cultured for 4 wk with periodic
immersion liquid culture to induce multiple bulblets from each segment, and then the bulblet induction medium
was changed into bulblet growth medium by employing a submerged liquid bioreactor system. This culture
method resulted in a nearly 10-fold increase in bulblet growth compared to conventional culture with solid
medium. About 20 000 cuttings of virus-free potato could be obtained from 120 singlenode explants in a 20-
liter balloon-type bubble bioreactor after 8 wk of culture. The percentage of ex vitro survival and root induction
of the cuttings was more than 95%. Other successful results were obtained from the micropropagation and
transplant production of chrysanthemum, sweetpotato, Chinese foxglove. Propagation systems via somatic
embryogenesis in Acanthopanax koreanum and thornless Araliaelata were established using a liquid
suspension of embryogenic determined cells. More than 500 000 somatic embryos in different stages were
harvested from a 10-liter balloon-type bubble bioreactor after a 6-wk culture. Further development of these
embryos in solid medium and eventually in the field was successful.
The bioreactor system could reduce initial and operational cost for micropropagation, but further development
of sophisticated technology might be needed to apply this system to plant micro propagation industries.
A bioreactor may also refer to a device or system meant to grow cells or tissues in the context of cell culture.
 These devices are being developed for use in tissue engineering.
 The bioreactors are modular in nature and carry out all the processes of fermentation in a single
contained environment.
 Bioreactor plays a core role in bioprocess.
 Stirred tank bioreactors are commonly used in fermentation industry.

10. References
The data is collected from following sources
 http://www.informit.com/articles/article.aspx?p=1652026seqNum=3
 http://www.sciencedirect.com/topics/neuroscience/bioreactors
 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1523360/pdf/1475-2859-5-21.pdf
 Kantarci, N., Borak, F., Ulgen, K. O. (2005). Bubble column reactors, 40, 2263–2283.
https://doi.org/10.1016/j.procbio.2004.10.004
 Nanda, S. (2008). Reactors and Fundamentals of Reactors Design for Chemical Reaction.
 Shonnard, D. (n.d.). Chapter 10 : Sterilization and Bioreactor Operation Sterilization Methods and
Kinetics : 10 . 4 Reasons for Sterilization Sterilization Agents Kinetics of Thermal Sterilization ( Death
), 1–20.
 Singh, J., Kaushik, N., Biswas, S. (2014). Bioreactors – Technology Design Analysis, 1(6).
 http://www.biologydiscussion.com/biotechnology/downstream-processing/stages-in-downstream-
processing-5-stages/10160
 Krishna Prasad, Nooralabettu (2010). Downstream Processing-A New Horizone in Biotechnology.
Prentice Hall of India Pvt. Ltd, New Delhi. ISBN 978-81-203-4040-4.