This document discusses different types of bioreactors. It begins by defining a bioreactor as an engineered device that supports a biologically active environment. It then classifies bioreactors as either suspended growth or biofilm reactors. The main types of bioreactors discussed are batch, continuous stirred-tank (CSTR), plug flow, packed bed, fluidized bed, and trickling filters. Applications mentioned include waste water treatment, food production, and reducing air pollutants. The document provides details on the operation and uses of these various bioreactor configurations.

1. BIOREACTORS
GAYATHRI
MOHAN

2. CONTENTS
• Introduction to Bioreactors
• Classification and types of Bioreactors
• Operation
• Applications of Bioreactors in waste water
treatment

3. BIOREACTORS
Bioreactor: A bioreactor may refer to any
manufactured or engineered device or system
that supports a biologically active environment.
A bioreactor is 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 or anaerobic.
They vary in size and complexity from a 10 ml
volume in a test tube to computer controlled
fermenters with liquid volumes greater than 100
m3.

4. Applications of Biotechnology

5. Classification of Bioreactors
Broadly classified as
 Suspended Growth Bio-reactors: Biological catalyst is suspended in
the growth medium. Eg: Batch reactors, CSTR’s, Plug Flow reactor
 Biofilm Bio-reactors: Microorganism are kept attached to a surface
and this type find major applicability in waste water treatment.
The different kinds of biofilm reactors include membrane,fluidized
bed, packed bed, airlift, and upflow , anaerobic sludge blanket
reactors.
Based on mode of operation
Batch
Continuous
Fed-Batch

6. Batch Reactors
• Reactants are charged in to the vessel at
the starting of operation and the products
are withdrawn at the end.
• Complete mixing of the reactor volume
• uniform composition everywhere in
reactor but changes with time
Eg: BOD digestion bottle

7. Continuously stirred tank
reactors• In CSTR, reactants and products are
continuously added and withdrawn.
 Micro- organisms that grow within the reactor
continuously replace the micro organisms
removed from the reaction in the effluent.
• The basic characteristic of the ideal CSTR is that
the concentration of the substrate and
microorganisms are the same everywhere
through out the reactor.
• Mechanical or hydraulic agitation is required to
achieve uniform composition and temperature
• Mainly used in industrial applications and in
waste water treatment where no sterile
conditions is needed

8. Applications of CSTR
• Activated sludge reactors are one of the widely used
CSTR s in waste water treatment.
• Ideal for growth associated products, ie, Primary
metabolites
• Other application include the production of single cell
proteins, ethanol production, Lactic acid production.
• One of the drawback is high power requirement for
mixing.
• High shear force may damage the cells.
• Also less productive strain will be dominant in a
continuous culture.

9. Plug Flow Reactors (PFR)
• Also referred to tubular reactor or piston flow
reactor. (PFR)
• Flow of fluid through reactor with order so
that only lateral mixing is possible.
• The liquid or slurry stream continuously
enters one end of the reactor and leaves at the
other end.
• Flow moves through the reactor with no
mixing with earlier or later entering flows.
• Concentrations of substrates are highest at
the entrance of the reactor, which tends to
make rates there quite high

10. Applications of PFR
• Mainly used in small laboratory scale production and
pilot-plant studies.
• A typical plug flow reactor could be a tube packed
with some solid material (frequently a catalyst) are
called packed bed reactors or PBR's. Sometimes the
tube will be a tube in a shell and tube heat exchanger.
• Plug flow reactors are used for the following
applications:
 Fast reactions
 Homogeneous or heterogeneous reactions
 Continuous production
 High-temperature reactions

11. Disadvantages
Major disadvantages are
Temperature is hard to control
High Maintenance cost

12. Packed Bed reactors
• The medium to which the microorganisms are
attached is stationary (e.g plastic media or pea
sized stones).
• Commonly packed bed reactors are used for
aerobic treatment of waste waters and are
known as tricking filters and or biological towers.
ADVANTAGES:
 There is improved contact between the waste
stream and the micro organisms .

13. Trickling filter

14. Fluidized Bed Reactor
• The fluidized bed reactor depends upon the attachment of particles
that are maintained in suspension by a high upward flow rate of the
fluid to be treated. The particles are often called biofilm carriers. The
carriers may be sand grains, granular activated carbon, diatomaceous
earth.
ADVANTAGES:
1. Uniform particle mixing
2.Uniform temperature gradients
3. The ability to operate reactor in continuous state.
DISADVANTAGES:
1. Increased reactor vessel size
2. pumping requirements and pressure drop
3. Pressure loss scenario

15. Fluidized Bed Reactor

16. Environmental application of Bioreactors
GASEOUS EFFLUENTS
Bioreactors provide better containment and superior environmental
controls that allow faster, more complete and cost-effective treatment
• 1. BIOFILTERS: Biofilters are beds of soil or compost, about 1 m deep, with
an underlying distribution system for the contaminated gas. As the
contaminant laden gas moves up through the moist bed, the pollutants
are removed by sorption and oxidized by the microbial population
immobilized in the bed.
• 2. BIOSCRUBBERS: Conceptually similar to conventional gas scrubbers,
Bioscrubbers are employed when heavier contaminant loadings, less
soluble contaminants or contaminant toxicity make biofilters
unsatisfactory. Activated sludge mixed in water is contacted with the
gaseous effluent in a packed bed absorption tower. Contaminants transfer
to the sludge-water slurry which is taken to holding or sedimentation
tanks where most of the degradation takes place.
Clarified liquor from the sedimentation tanks is recycled to the absorption
column.

17. Bioscrubber

18. ARTIFICIAL WETLAND, OR 'REED BED'
• Bioreactor systems for reduction of biochemical oxygen
demand (BOD 5 ) and total suspended solids (TSS) in
municipal and industrial wastewaters.
• Aquatic plants such as bulrush, cattails, common reed, water
hyacinth, swamp potato and duck potato rooted in rock and
gravel media beds flooded with wastewater flowing though
the bed and root zone, make-up the wetland filters.

19. Conclusion
Bioconversion of wastes to harmless substances or
higher value products already has a significant role in
environmental pollution control and improved resource
utilization. Both in- situ and bioreactor based treatment
processes are experiencing rapid development and
increasing deployment in practical applications.

21. Questions????