Design and Operation of a Laboratory Fermentor W. H. BARTHOLOMEW, E. 0. M O W , AND M. R. SFAT Merck & Co., Znc., Rahtwy, N. J.
A laboratory fermentor is described which is useful in obtaining information for correlation with large scale fermentations. Operational procedures are given, and data are presented showing the degree of replication that can be achieved. Important variables needing close oontrol are emphasized. ~
and several mechanically agitated fermentors have been deli, id, 16,i7). scribedin which such aeration is possible (8,9, When fermentations using molds and actinomycetes were considered, mechanical agitation was likewise found to be necessary to obtain optimum aeration. A fermentor using high speed stirring was described for the production of gluconic acid (2). The rotating drum fermentor was found to be satisfactory for a number of mold and bacterial fermentations (7,1941 ). Yeast fermentors have been adapted to submerged fermentation employing molds and actinomycetes. The laboratory fermentors that have been described are unsatisfactory for this laboratory's requirements because most of them are radical departures from conventional large scale fermentors, so that data obtained in them are not readily translatable to large scale operation. It was desired to have a laboratory fermentor which is geometrically and mechanically similar to large scale equipment, in order to study the effects of aeration, agitation, and other variables. These fermentors have been useful for
Figure 1. General View of Laboratory Fermentors
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UBMERGED laboratory fermentations have been performed in a variety of equipment such as shake flasks, aerated jars
and bottles, and mechanically agitated fermentors. Some of the fermentors used to grow yeast consisted of metal cans, borosilicate glass jars and bottles, and wooden tubs with aeration supplied through the use of canvaa bags, Carborundum, and sintered glass (io,id, la). Recently, it has been shown that maximum yields of yeast are obtained only under conditions of intense aeration, 1__3
Figure 2. Detail Diagram of Laboratory Fermentor
2% inch in diameter 2. Agitator shoulder, 0.5 inch long, 0.5 inch in diameter 3. Upper Graphitar thrust bearing, 0.250 * 005 inoh long, 0.8128 $ g i n o h in outside diameter, **/uinoh in imide diameter 4. Thrust water, 0.125 inch thick, 0.75 inoh in diameter. Force-fit to shaft 5. Lower Graphitar thrust bearing, 0.250 .h 005inchlong, 0.8128 inch inoh in inaide diameter in outside diameter, 0.3126 6. Paokiny gland 0.5 inch long *6/n inch in outside diameter, *Vuinch in i m d e diaheter, 1/1* in& oollar, '/a inah in diameter 7. Stuffing box head, made from hex stock and turned to fit 8 Jam nut hex stock 9' Air line 'I/& inch standard pipe 10: Thermdmeter well, 7/16 inch in outside diameter, ( / I # inch in inside diameter, extends 9 inches into fermentor 11. Wing nut 12. Fermentor head plate, 0.5-inch plate, 8 inches in diameter 13. Rubber kasket 14. Inoculahon port with cap 15. Union 16 Stud 17: Cylindrical Pyrex museum jar 6 inches in diameter 12 inohes tall 18. Bafee (four), )/a inch wide, 11:s inches long, No. la' gage 19. Sparger 20. Four-bladed turbine impeller, 3 inches in over-all diameter 21. Tie ring 22 Rubberpad 23: Fermentor base plate, 0.5-inch plate, 8 inches in diameter 24. Poaitionhg lug 25 Sna ring 26: Paagng 27. Graphitar main bearing, 1.25 inches long, 0.8128 ?Einch in outside diameter,'O.L125 ?Einch in imide diameter 28. Stuffing box fixed section, 2.395 inches lone, 1.25 inches in outside diameter, 0.8125 inch in imide diameter 29. Water addition line? Va-inch standard pipe 30. Gse outlet Ime. l/r-inch standard pipe 31. Antifoam addition line I/a-inch standard pipe 32. Sampling line, I/r-inch'standard pipe 1. Agitator shaft, 15 inches long, 0.3125
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1827
Val. 42, No. 9
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1828
obtaining such information (I). The following speoifieations had to be met: Sufficiently small to fit B considerable number of units into s laborstory assembly, and sufficiently lar so that the necessary sample withdrawals would be a tolerable t%ction of ths fermentor charge. Cspable of B wide range of operating variables. Compare fworably with shake 5 s k s snd plant fermentors in oroduotivitv and outout rate. Versatile-with regard to operation, control, and oleansing; du≤ and mntaminationproof. Provide visual observation of the fermentation at d l times.
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This p a p deacrihes 8uch a laborstory fermentor, emphnsizea certain operating variables which need strict control, and presents -me of the results obtained in fernientat,ions performed in this equipment. DESCRIPTION OF FER.MENTATION EQUIPMENT
The laboratory fermentation unit consists of eighteen identieel &liter fermentors whioh are divided into six equsl groups, esoh group equipped with a thermostatieally controlled wster bath and vansbles ed agitator drives. Air, electricity, water, snd gas are proVi&. A general view of the unit is shown in Fi re 1 The fermentor (Figure 2) consists hesioally of B bo%, R 'sup p r t , and FA head. The hody contains the fermenting broth; the aupport positions the fermentor in a water bath and supports the rest of the fermentor; and the head doses the fermentor and s u p ports the agitator shaft sparger, haBes, thermometer well, gamflingpipe off-gas outlet: inmulation port, and two other openings or t e adaition of sntifoam and water. All metailio elements are of T pe 316stninlesssteel. d e fermentor body is B cylindricsl horosiliaste glass m w u m jar, 12 inches tall and 6 inches in diameter, The jar should be aeleoted to ensure B ti ht fit with the head, amplo mom for easy insertion of internal e%ments, and freedom from strains in the g1s.m. With the head in place, the jar ip. eslibrsted for volume. The fermentor support consists of 5 0.Rinch plate, 8 inches in diameter which is fitted with two sitioning lugs 180" apsrt and four studs equally spaced a o u n E "inch diameter. The lug slots open oloekwue, 80 that the clockwise direction of the agitar tor does not dieengage the fermentor from the water heth. A circuler '/,,-inch recess in the top of the l x w plntc holds R 0.125 ioehgurnmbherpsd.
over-all diameter. The turbine consists of a 16uaue disk 2 inches in dismeter. Four curved blades of 1 6 g a sG& 0.5 iooh wide and spproximatel~ 0.75 inoh long a?tacf%lded, BO that the blades are 0.25 ine m the disk an split by the disk. Fully ba&d conditions rn provided hy four O.62S-ineh stri s 11.5 inches long cut from No. 16 gage mater%, which are e q w d s p e e d around a diameter of 4.375 inches. Bottoms of the b a l Res &re taok-welded to a tie ring and the tops w e fastened to the fernentor head withstud screws. The air line extends through the head 1.5 inches into the fermentor. terminatine with B union to whioh the soweer is at-
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