Types of fermenter

different types of fermenter.

1. TYPES OF FERMENTER BY M.Vharshini 2 ND YEAR B.Sc. BMS

2. SYNOPSIS Waldhof fermenter Acetators and cavitators Tower fermenter Cylindro -conical vessels Air lift fermenter Deep jet fermenter The cyclone column Rotating disc fermenter

3. WALDHOF FERMENTER Yeast growth in sulphite waste liquor led to the development of Waldhof fermenter. The fermenter was Carbon steel, clad in stainless steel Diameter – 7.9m High-4.3m Central draught tube -1.2m in diameter Draught tube was held by tie rods attached to the fermenter walls Operating volume—225,000dm 3 of emulsion(broth & air) and broth without air—100,000dm 3

4. Non sterile air was introduced into the fermenter using the rotating – pin wheel type of aerator composed of open ended tubes rotating at 300 rpm. The broth passed down the draught tube from the outer compartment which reduced the foaming.

5. ACETATORS AND CAVITATORS Fundamental studies on vinegar production showed that: Acetobacter cells remain active in stirred aerated fermenter , distribution of air had to be almost perfect within the entire contents of the vessel The full-scale problem was solved by the use of self aspirating rotor — the turning rotor sucked air and broth and dispersed the mixture through out the rotating stator. The aerator also worked without a compressor and was self-priming. In Vinegar fermentation—foam & chemical antifoams are not feasible because they decrease aeration efficiency and quality of vinegar. Therefore Mechanical defoamer was incorporated into vessels and as foam builds up it is forced into a chamber in which the rotor runs at 1,000 to 1,450 rpm .

6. Centrifugal force breaks the foam & separates it into gas & liquid. The liquid is pumped back into the fermenter & gas escapes by a venting mechanism. Uniform distribution of air bubbles was obtained by means of the circulation pattern created by the centrally located draught tube.

7. Self –priming aerator A- hollow body of turbine B-openings radially arranged C- verticle sheets D-stator E & F-upper and lower ring on the turbine G & H-upper and lower ring of stator

8. TOWER FERMENTOR An elongated non mechanically stirred fermenter having the aspect ratio 6:1 for tubular sections and 10:1 for overall, through which there is a unidirectional flow of gases . Simple tower fermenter are those with air sparger at the base ; used for citric acid production This batch fermenter is in the form of glass column having a ht:diameter ratio of 16:1 and with a volume of 3dm 3 . Humid sterile air was supplied through the base.

9. types Single staged: e.g. Hall and howard’s beer fermentor : water jacketed tubes of various dimensions inclined at an angles of 9ºto90º. Intermediate staged: settling zones of various designs e.g. Shore et al’s beer fermentor . It has sectioned perforated plates for max. beer production Multi staged: number of perforated vessels are used. e.g.Owen (1948) and victorero (1948) et al for brewing beer.

10. CYLINDRO-CONICAL VESSELS Used in Brewing of lager . First proposed by Nathan. The vessel consists of stainless steel vertical tube with a hemispherical top & conical base with an included angle of approx 70 degree. Aspect ratio—3:1 Fermenter Height—10 to 20m Operating volumes—150,000to 200,000dm 3 Vessels are not normally agitated unless particularly flocculant yeast is used

11. Small impeller may be used to ensure the homogeneity when filling with wort . In the vessel , wort is inoculated with yeast and fermentation proceeds for 40 to 48hrs. Mixing is achieved by the addition of carbon dioxide bubbles—rise rapidly in the vessel. Temperature control is monitored by probes positioned at suitable points within the vessel. A no. of cooling jackets are fitted to the wall to regulate & cause flocculation & settling of yeast.

12. The fermentation is terminated by the circulation of chilled water via cooling jackets which results in yeast flocculation. Thus it is necessary to select yeast stains which will flocculate readily in the period of chilling. ADVANTAGES OF THIS VESSEL IN BREWING: Reduces process times — increased movement within the vessels. Primary fermentation and conditioning carried out in same vessel. The sedimented yeast—easily removed since yeast separation is good. Maturing time may be reduced by gas washing with carbon dioxide.

13. THE CYCLONE COLUMN Dawson developed cyclone column fermenter for the growth of filamentous cultures Culture liquid—pumped from bottom to top of the cyclone column through a closed loop Descending liquid ran down the walls of the column in a relatively thin film Nutrients & air—fed near the base, exhaust gases are left at the t op Advantages: Good gas exchange, lack of foaming, limited wall growth

14. PARTS OF CYCLONE – COLUMN FERMENTER I – cyclone column II – circulating pump III – recirculating limb

15. AIR LIFT FERMENTER It is essentially a gas tight baffled riser tube connected to the downcomer tube. Air or gas mixture—introduced into the base of the riser by a sparger during normal operating conditions. The driving force for circulation of medium in vessel is produced by the differences in density between the liquid column in the riser and in the down comer. This type of vessel can be used for continuous culture . It would be uneconomical to use a mechanically stirred fermenter to produce SCP from methanol as a carbon substrate ;as heat removal would be needed in external cooling loops because of high rate of aeration and agitation required to operate this process.

16. To overcome these(Use of mechanical stirrers,cooling ) problems air lift fermenters with outer or inner loops were chosen. ICI plc initially used an outer loop system in their pilot plant—all other companies preferred an inner loop design for large scale operation. In ICI plc continuous process air and gaseous ammonia were introduced at the base of the fermenter.

17. Sterilized methanol, other nutrients and recycled spent medium were also introduced into the down comer. Heat from exothermic fermentation—removed by surrounding part of the downcomer with cooling jacket in pilot plant. At full scale it was found necessary to insert cooling coils at the base of the riser. Unfortunately the production of SCP for animal feed was unprofittable because of the price of methanol etc.

18. TYPES OF ALR: 1- INTERNAL LOOP ALR 2-EXTERNAL LOOP ALR

19. DEEP JET FERMENTER Design of continuous culture fermenter —necessary mechanical power input with a pump to circulate the liquid medium –gas entrainer Two construction—gas entrainer nozzles Injector Ejector Injector—jet of medium—surrounded by a jet compressed air Gas from outlet enters the large tube with the nozzle velocity 5 to 100m/s Expands in tube—form large air bubbles—dispersed by the shear of water jet

20. Ejector—liquid jet enters into a large converging-diverging nozzle—entrains the gas around the jet Gas is sucked into the converging-diverging jet is dispersed in that zone Aerated medium is pumped by a multiphase pump through a broth cooler to an air entrainer above the fermenter

21. Air medium mixture falls down—conical shaft at high velocity—creates a turbulence in the fermenter 2/3 rd of the exhaust gas is vented from the fermenter head space—reminder via multiphase pump Oxygen transfer rate 4.5g/dm 3 h with an energy consumption of 1kW/ hkg

22. DEEP JET FERMENTER

23. PACKED TOWER Application for the immobilized cells A vertical cylindrical column is packed with pieces of some relatively inert material( woodshavings , twigs, coke, polythene) Both medium and cells are fed into the top of the packed bed Once cells get adhersed to support(thin film)—fresh medium added at the top of the column—fermented medium removed from the bottom of the column

24. Vinegar generator—ethanol is oxidised to acetic acid by strains of acetobacter Mainly used for sewage and effluent treatment In treatment with gas liquor a column was packed with the height—7.9m with Dowpac—polystrene derivatives

25. ROTATING DISC FERMENTER Effluent treatment Utilize a growing microbial film on slow rotating discs to oxidizes the effluent ANDERSON and BLAIN—construct small fermenter (40dm 3 ) Range of filamentous fungi— Aspergillus , Rhizopus , Mucor , Penicillium — grow on polypropylene discs Obtain yield—80g/dm 3 —production of citric acid using A.niger

26. reference Principles of fermentation technology Peter F. Stanbury , Allan Whitaker

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