Enzyme reactors

This presentation is about different enzyme reactors used in industrial processes

1. Enzyme reactors Presented by steev Marcial nizigiyumuremyi Iii rd Bsc Biotechnology

2. definition Enzyme reactors are vessels employed to carry out the desired conversion of raw materials using enzymes. Enzymes may be immobilized or not during the process. Enzyme immobilization is the process of confining the enzyme molecules to a solid support over which a substrate is passed and converted to products . The aim of an enzymatic reactor is to allow enzyme and substrate to come into contact for a sufficient period of time for reaction to take place; enzyme and product may then easily be separated.

3. Types of enzyme reactors Batch reactors Continuous Flow Reactors

4. Batch reactors Essentially large agitated tanks in which enzyme and substrate are placed. The reaction is allowed to progress to its end after which the reactor is drained and the product is separated from the enzyme If soluble enzyme is employed, it is normally separated by subsequent denaturation ( i.e. by heat treatment) Suitable with cheap enzymes Costly enzymes can be used also when immobilized and recovered by centrifugation or filtration Risk of enzyme destruction during recovery process Use of immobilized enzymes has limited potential in batch reactors

5. Types of batch reactors Stirred tank for soluble enzymes Stirred tank for immobilized enzyme Stirred tank with immobilized basket paddles Stirred tank with immobilized enzyme basket baffles Total recycle packed bed reactor Total recycle fluidized bed reactor

6. Continuous-flow reactors Principle behind this reactor is the continuous addition of addition of substrate and exit of product from the reactor. Subtypes: continuous-flow stirred-tank reactor packed-bed reactors hollow-fiber reactor Fluidized-bed reactors

7. Continuous stirred tank reactor It consists of a stirred tank with a separate substrate inlet and reactor mix ( i.e. product) outlet By careful choice of size of the tank, enzymatic activity and rate of addition of substrate, the percentage of conversion of substrate into product can be adjusted as desired. E.g.: a low flow rate, a large reactor size (and hence long residence times) and high enzymatic activity will give high product yields

8. Continuous stirred tank reactor ctn The immobilized enzyme may be kept inside the reactor by filtration of the stream of product, incorporating a subsequent settling stage, by immobilizing the enzyme on magnetically active particles and retaining it in a magnetic field (which also serves to stir the particles) or by immobilizing the enzyme to the paddles of the agitator shaft Possibility of combination with an ultrafiltration process which permits the use of soluble immobilized enzymes in the reactor in case of soluble or colloidal s ubstrate

9. Basic design of an cstr

10. Alternatives for an Cstr

11. Packed-bed reactors Here the catalyzer(enzymes) is packed into a column and to make the substrate flow through the column in such a way that the product is obtained at the outlet . I deal when the flow rate profile across a transverse cross section of the column is perfectly flat; systems like this are known as plug-flow reactors T he column can be constructed as a tall column or a fiat bed The degree of reaction, for a fixed flow rate, is proportional to the length of reactor column

12. When substrate is added through the upper part of the column the particles of catalyst then tend to jam together, plugging the column the enzyme may be immobilized onto a membrane or a sheet of material ( ie a paper filter) and confined in a filter-press arrangement Diameter of immobilized enzyme pellets: 1-3mm Use pellets of uniform size and in an upward flow of substrates. Matrix used is fairly rigid

13. Disadvantages of packed-bed reactors Packed bed reactors may become clogged up by colloids or precipitates present in the reaction mixture . Temperature or pH is not easily regulated especially in reactors of >15 cm diameter. Channels may form in the reactor bed due to excessive pressure drop, irregular packing or uneven flow stream

14. Variations of Packed-bed reactors

15. Hollow fiber reactors They are thick-walled tubes about the diameter of a human hair. The tubes are made of semipermeable material, such as cellulose, which confines large molecules (enzyme) while allowing free passage of small ones (substrate and product). Hollow fibers are packed into a column. The enzyme can be retained in the interior of the fibers and the stream of substrate passes round the outside of them. The substrate will diffuse through the wall of the fiber, reacting with the enzyme: the product can diffuse back through the wall of the fiber to the flow stream. Alternatively , it is possible to pass the substrate through the centre of the fiber which is bathed by a solution of enzyme

16. Advantages of hfr Easy setup, reduced oversight Small size Low cost High product concentration Reduced capital costs Widely used in hybridoma technology

17. Fluidized bed reactors They are a hybrid of continuous flow- stirred tank and packed-bed reactors . The immobilized enzyme is loosely packed into a column and the stream of substrate passes from the lower to the upper part of the column at a fixed rate which is sufficiently high to lift and mix the particles of immobilized enzyme within the column . Because the particles of immobilized enzyme are denser than the reaction medium they remain in the lower part of the column, unless the flow rate is so high that the particles of enzyme can be transported to its upper part.

18. In this way when the substrate is introduced into the column as a flowing stream, the bed of solid particles is transformed into a fluid-like state making the particles of immobilized enzyme separate and move about in the column. The column acquires the appearance of a gently boiling liquid. This effect is quite efficient at mixing catalyst with substrate

19. Applications of enzyme reactors Bioconversion of complexes substances using immobilized enzymes Protein analysis HPLC Industrial applications: Synthesis and/or modification of antibiotics, steroids and hormones, vitamins, amino acids, organic acids, radioactive compounds Analytical and medical applications

20. References Applications of Immobilized Enzymes ,MANUEL G ROIG,* J FELIPE BELLO, FERNANDO G VELASCO, CARMEN D DE CELIS and JUAN M CACHAZA www.rpi.edu/dept/chem-eng/Biotech-Environ/IMMOB/typesofreactors.html http://hollow-fiber.com/2015 www.wikipedia.com www.google.com/images

21. T H A N K Y O U Nistem’s Design