Fluidised Bed Bioreactor

A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions.
In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid.
This process, known as fluidization, imparts many important advantages to the FBR.
As a result, the fluidized bed reactor is now used in many industrial applications

1. Fluidized bed bioreactor SUBMITTED BY : Manasi Acharjee ( 16010400x) Trishna Das ( 1601040xx) Dibyajyoti Deka ( 1601040xx) Prosanta Pegu ( 1601040xx)

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3. A  bioreactor  may refer to as any manufactured or engineered  device or system that supports a biologically active environment. On the basis of  mode of operation , a bioreactor may be classified as  batch, fed batch or continuous What is a Bioreactor?

4. Fluidized Bed Bioreactor A  fluidized bed reactor  ( FBR ) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. This process, known as fluidization, imparts many important advantages to the FBR. As a result, the fluidized bed reactor is now used in many industrial applications

5. Fluidized bed reactors are the most popular configurations employed from laboratory to commercial scale. Fluidization is a process in which the upward flow of a fluid suspended particles. Fluidization is first used in the 1920s for coal gasification.

6. The fluidized bed bioreactors are generally operated in co-current flow. The particles used in FBBs are of three different types: i. Inert core on which the biomass is created by cell attachment. ii. Porous particles in which the biocatalyst is absorbed. iii. Cell aggregates. The solid substrate (the catalytic material upon which chemical species react) material in the fluidized bed reactor is typically supported by a porous plate, known as a distributor . The fluid is then forced through the distributor up through the solid material. WORKING PRINCIPLE

7. As the fluid velocity is increased, the reactor will reach a stage where the force of the fluid on the solids is enough to balance the weight of the solid material. This stage is known as incipient fluidization and occurs at this minimum fluidization velocity. Once this minimum velocity is surpassed, the contents of the reactor bed begin to expand and swirl around much like an agitated tank or boiling pot of water. The reactor is now a fluidized bed. A bed of immobilized enzymes is fluidized by rapid upward flow of the substrate or in combination with a liquid or secondary fluid stream. Depending on the operating conditions and properties of solid phase various flow regimes can be observed in this reactor.

8. FACTORS: 1.Mass transport rate. 2.Bubble residence time. 3.Rate of reaction .

9. Uniform Particle Mixing:  Due to the intrinsic fluid-like behavior of the solid material, fluidized beds do not experience poor mixing as in packed beds. This complete mixing allows for a uniform product that can often be hard to achieve in other reactor designs. The elimination of radial and axial concentration gradients also allows for better fluid-solid contact, which is essential for reaction efficiency and quality. Advantages Uniform Temperature Gradients:  Many chemical reactions require the addition or removal of heat. Local hot or cold spots within the reaction bed, often a problem in packed beds, are avoided in a fluidized situation such as an FBR. In other reactor types, these local temperature differences, especially hotspots, can result in product degradation. Thus FBRs are well suited to exothermic reactions. Researchers have also learned that the bed-to-surface heat transfer coefficients for FBRs are high . The increase in fluidized bed reactor use in today's industrial world is largely due to the inherent advantages of the technology. 1 2

10. Ability to Operate Reactor in Continuous State:  The fluidized bed nature of these reactors allows for the ability to continuously withdraw product and introduce new reactants into the reaction vessel. Operating at a continuous process state allows manufacturers to produce their various products more efficiently due to the removal of startup conditions in batch processes . CONTINUED … 3 USEFUL IF THE REACTION INVOLVES THE UTILISATION OR RELEASE OF GASEOUS MATERIAL. 4

11. Disadvantages Increased Reactor Vessel Size:  Because of the expansion of the bed materials in the reactor, a larger vessel is often required than that for a packed bed reactor. This larger vessel means that more must be spent on initial capital costs. Pumping Requirements and Pressure Drop:  The requirement for the fluid to suspend the solid material necessitates that a higher fluid velocity is attained in the reactor. In order to achieve this, more pumping power and thus higher energy costs are needed. In addition, the pressure drop associated with deep beds also requires additional pumping power. As in any design, the fluidized bed reactor does have it draw-backs, which any reactor designer must take into consideration. 1 2

12. Particle Entrainment:  The high gas velocities present in this style of reactor often result in fine particles becoming entrained in the fluid. These captured particles are then carried out of the reactor with the fluid, where they must be separated. This can be a very difficult and expensive problem to address depending on the design and function of the reactor. This may often continue to be a problem even with other entrainment reducing technologies . 3 CONTINUED … DIFFICULTY IN SCALLING-UP THESE REACTIONS. 4

13. APPLICATIONS OF FLUIDIZED BED BIOREACTOR IN WASTE WATER TREATMENT: The use of fluidized bed reactor in wastewater treatment, represents a unique opportunity for cost-effective treatment of wastewater containing recalcitrant pollutants ( compounds  that are slowly biodegradable or non-biodegradable are known as recalcitrant compounds , and range from simple halogenated hydrocarbons to complex polymers) Although the application of fluidized bed reactor in biological wastewater treatment is well established with many large-scale plants in existence, its application in advanced oxidation processes is mostly at laboratory-scale.

14. A major application of FBBs is fluidized catalytic cracking which was developed in 1940s. Anaerobic fluidized-bed platform has been tested as an anaerobic platform for the high strength and high solids waste streams such as the municipal sludge's and corn ethanol thin stillage.

15. REFERENCES: IUPAC ,  Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) " bioreactor ".  Reference : Howard, J. R. (1989).  Fluidized Bed Technology: Principles and Applications.  New York, NY: Adam Higler . Reference : Applications of fluidized bed reactors in wastewater treatment – A review of the major design and operational parameters https://www.sciencedirect.com/science/article/pii/S0959652616314901