This presentation gives all the required information about pack bed bioreactor, including, advantages, disadvantages, applications and even how to overcome the disadvantages. Packed bed bioreactor is the major type of bioreactor used in waste water treatment as it involves the usage of catalyst. There are different types of packed bed bioreactors and they are used according to the desired product. There is picture representation and also tabular form of differentiation. I have also mentioned the references at the end.

1. PACKED BED
REACTOR
MADE BY: SNEHAL SALUNKHE
D.Y. PATIL DEEMED TO BE UNIVERSITY, SCHOOL OF
BIOTECHNOLOGY AND BIOINFORMATICS, NAVI
MUMBAI
Course: B.Tech Biotechnology
Year: 3rd (6th semester)
Session: 2018-2019

2. INTRODUCTION
•In chemical processing, a packed bed is a hollow tube, pipe, or other vessel that
is filled with a packing material. The packing can be randomly filled with small
objects like Raschig rings or else it can be a specifically designed structured
packing. Packed beds may also contain catalyst particles or adsorbents such as
zeolite pellets, granular activated carbon, etc.
Fig. 1 Packed bed
reactor

3. • The purpose of a packed bed is typically to improve contact
between two phases in a chemical or similar process.
• Packed beds can be used in a chemical reactor,
a distillation process, or a scrubber, but packed beds have also
been used to store heat in chemical plants.
• The packed bed reactors are widely used with immobilized
cells.

4. STRUCTURE/ CONSTRUCTION

6. ADVANTAGES
• By using a packed bed reactor is the higher conversion per weight of catalyst
than other catalytic reactor.
• The reaction rate is based on the amount of the solid catalyst rather than the
volume of the reactor.
• Low operating cost and low maintenance by using this kind of reactor.
• The process using packed bed reactor operates continuously.
• Little wear on catalyst and equipment.
• Simple analysis
• Little loss or attrition.
• Only practical, economic reactor at very high pressures.
• Usually high ratio of catalyst to reactants long residence time complete reaction

7. CHALLENGES/ LIMITATIONS
For the first aspect which is TEMPERATURE CONTOL and the challenge that have
to face in are:
1. ENDOTHERMIC REACTIONS MAY DIE OUT
2. EXOTHERMIC REACTION MAY DAMAGE THE REACTOR
3. SELECTIVELY CONTROL

8. SINGLE BED REACTOR MULTI-BED REACTOR MULTI-TUBE REACTOR

9. SINGLE BED REACTOR MULTI-BED REACTOR MULTI-TUBE REACTOR

10. For the second aspect which is PRESSURE DROP:
1. Friction between the gas and particle phase result in a pressure drop.
2. High pressure drop will result to high compression cost.
3. Some systems have low tolerance for pressure drop.
4. The pressure drop is mainly dependent on reactor length, particle diameter, void
fraction and gas velocity.

11. The third aspect of limitation is CATALYST DEACTIVATION:
The catalyst gets deactivated if the active sites get contaminated.
Sulphur compound deactivate Ni-catalyst -Desulfurization is often necessary
prior to reforming.
Formation of carbon deposit deactivate the catalyst - Large carbon deposits
may clog the tubes, causing hot-spots that damage the reactor.
Catalyst regeneration is necessary.

12. DISADVANTAGES
• Large temperature gradient or undesired thermal gradient may occur.
• Inefficient heat exchange
• Suitable for slow-or-non-deactivating processes.
• Poor temperature control.
• Channeling may occur.
• Unit may be difficult to service and clean.
• Swelling of the catalyst, deformation of the reactor.
• Regeneration or replacement of the catalyst is difficult- shut down is required.
• Pore diffusional problems intrude in large pellets

13. OVERCOMING THE DISADVANTAGES
• Monolithic supports will overcome the problems of non-uniform flow
patterns, plugging high pressure for small pellets and pore diffusional
problems.
• Temperature control problems are overcome with:
1. Recycle.
2. Internal and external heat exchanges.
3. Staged reactors
4. Cold shot cooling
5. Multiple tray reactor- fluid redistributed and cooled between stages
and catalyst is easily removed which varied from tray to tray.
6. Use of diluents.
7. Temperature self-regulation with competing reactions, one endo and
one exothermic.
8. Temperature control by selectivity and temporarily poisoning the
catalyst

14. APPLICATIONS
• Synthesis of gas production
• Methanol synthesis
• Ammonia synthesis
• Fischer-Tropsch synthesis
• valorization of food
• Gas cleaning (adsorption)
• Waste treatment
• Nutraceutical synthesis
• Packed column bed distillation is used to enhance contact
between vapor and liquid instead of trays packing

15. PACKED BED BIOREACTOR FOR THE ISOLATION
AND EXPANSION OF PLACENTAL-DERIVED
MESENCHYMAL STROMAL CELLS
ABSTRACT
Large numbers of Mesenchymal stem/stromal cells (MSCs) are required for
clinical relevant doses to treat a number of diseases. To economically
manufacture these MSCs, an automated bioreactor system will be required.
Herein we describe the development of a scalable closed-system, packed bed
bioreactor suitable for large-scale MSCs expansion. The packed bed was
formed from fused polystyrene pellets that were air plasma treated to endow
them with a surface chemistry similar to traditional tissue culture plastic. The
packed bed was encased within a gas permeable shell to decouple the
medium nutrient supply and gas exchange. This enabled a significant
reduction in medium flow rates, thus reducing shear and even facilitating
single pass medium exchange. The system was optimised in a small-scale
bioreactor format (160 cm2) with murine-derived green fluorescent protein-
expressing MSCs, and then scaled-up to a 2800 cm2 format. We demonstrated
that placental derived MSCs could be isolated directly within the bioreactor
and subsequently expanded. Our results demonstrate that the closed system
large-scale packed bed bioreactor is an effective and scalable tool for large-
scale isolation and expansion of MSCs.

16. GFP-mMSC expansion in a scaled-up packed bed bioreactor (A)
The fold expansion of GFP-mMSC in a scaled-up bioreactor under
0.5 ml/min perfusion with T175 flask control (n = 4). (B) Glucose
and lactate levels in the bioreactor (n = 3). (C, D, E & F) IVIS
imaging of the fluorescent intensity of PI stained GFP-mMSC in
the bioreactor.

17. REFERENCES
• www.wikipedia.org
• https://www.scribd.com/document/223520329/Packed-Bed-
Reactor
• https://journals.plos.org/plosone/article?id=10.1371/journal.po
ne.0144941
• www.google.com