United States Patent (19) 11 Patent Number: 5,177,008 Kampen 45) Date of Patent: Jan

IIII USOO51 77008A United States Patent (19) 11 Patent Number: 5,177,008 Kampen 45) Date of Patent: Jan. 5, 1993

54 PROCESS FOR MANUFACTURING 5,019,263 5/1991 Haag et al...... 210/500.25 ETHANOL AND FOR RECOVERING GLYCEROL, SUCCINIC ACID, LACTIC ACID, FOREIGN PATENT DOCUMENTS BETAINE, POTASSIUM SULFATE, AND 51-039625 5/1976 Japan ...... , 101/OO FREE FLOWING DISTILLER'S DRY GRAIN 55-045067 ll/1980 Japan ...... 10/2 AND SOLUBLES OR A SOLID FERTILIZER THEREFROM OTHER PUBLICATIONS Chico et al., "L. Alanine as an end product of glycolyi Inventor: Willem H. Kampen, 447 Blue Rock sis in saccharomyces-cerevisiae growing under differ Dr., Charlotte, N.C. 28213 ent hypoxic conditiones," CA79: 177022 Bioss. 1978. Appl. No.: 537,779 "Recovery of Chemicals Such as Glycerol, Dextrose, and Amino Acids from Dilute Broths', Brian D. Burris, Filed: Jun. 18, 1990 pp. 1-39. Related U.S. Application Data Primary Examiner-Robert J. Warden Assistant Examiner-Timothy M. McMahon Continuation-in-part of Ser. No. 381,179, Jul. 18, 1989, which is a continuation-in-part of Ser. No. 136,415, Attorney, Agent, or Firm-Rhodes, Coats & Bennett Dec. 22, 1987, abandoned. (57) ABSTRACT Int. Cl...... G2P 7/20 This invention relates to the manufacture of ethanol and U.S. C...... 435/139; 435/145 the recovery of economically significant amounts of 435/146; 435/59: 435/16 such by-products therefrom as glycerol, betaine, L (58) Field of Search ...... 435/139, 141, 145, 146, pyroglutamic acid, succinic and lactic acid, potassium 435/159, 161, 163 sulfate and a free flowing distiller's dry grain and solu bles useful as an animal feed or a component of food for (56) References Cited humans or as a premix for agricultural fertilizer and/or U.S. PATENT DOCUMENTS a feed additive. An important aspect of the recovery 2, 69.245 8/1939 Hildebrandt et al...... , 195/38 step is the utilization of a crossflow microfiltration sys 2,772.207 1/1956 Frankel et al...... 195/38 tem which includes inorganic membranes for the classi 4,336,335 6/982 Muller et al...... 435/33 fication of the stillage. 4,359,430 l/1982 Heikkila et al. ... 260/5013 4,689,048 8/1987 Fortsch et al...... 210/650 37 Claims, 2 Drawing Sheets

PREPARE MAS CEAN BACKSET OSTELATON ETHANo. (CENTRIFUGING) MICROF TRATION (PARTAL SOFTENING) (HYDROLYSIS OF SOLIDS DRYNG PROTEINACEOUS MAERA (OR)

EWAPORATON ION EXCHANGE

POTASSUMSUFATE REMOVA

CHROMATOGRAPHIC SEPARATION - EWAPORATION

KON EXCHANGE - cg3NSSRARS (ION EXCHANGE) EWAPORATION CONCENTRATION PURIFICATION

DISTILLATKON EWAPORATION

L-PYROG UAMC REFINING ACD

SUCCNC BETAINE LACTIC - LACID ACID U.S. Patent Jan. 5, 1993 Sheet 1 of 2 5,177,008

PREPARE MASH CLEAN BACKSET DISTILLATION ETHANOL

(CENTRIFUGING) MSEESNPARTIAL SOFTENING SOLDS DRYIN EFSF Sious OLIDS DRYING (OR) SOLID PREMIXFERTLIZER DDG(S)

EVAPORATION CONDENSATE ION EXCHANGE

POTASSUM SULFATE REMOVAL

CHROMATOGRAPHCSEPARATION F EVAPORATION

ION EXCHANGE CHROMATOGRAPHC SEPAPARATION(S) EVAPORATION (ON EXCHANGE) CONCENTRATION

PURIFICATION

DISTILLATION EVAPORATION L-PYROGLUTAMC REFINING ACD acrossGLYCEROL SUCCNC estangBETANE LACTIC F.G. U.S. Patent Jan. 5, 1993 Sheet 2 of 2 5,177,008

PREPARING MASH FROM SUGAR BEET MOLASSES CLEAN BACKSET

DISTILLATION ETHANOL

MCROFILTRATION SOLDS DRYNG

ENZYMATC HYDOLYSS FERTLIZER PRE-MX PROTEINACEOUS MATTER

EVAPORATION CONDENSATE

K2SO4 REMOVAL

CHROMATOGRAPHC SEPARATION I. EVAPORATION

EVAPORATION

EVAPORATION CHROMATOGRAPHC SEPARATION II BETAINE REMOVAL

ION EXCHANGE / EVAPORATION DISTILLATION / REFINING

GLYCERNE BETAINE (HC) FIG.2 5,177,008 1 2 "Recovery of Chemicals Such as Glycerol, Dextrose, PROCESS FOR MANUFACTURING ETHANOL and Amino Acids from Dilute Broths' which was AND FOR RECOVERING GLYCEROL, SUCCINIC presented to the "International Conference on Fuel ACID, LACTIC ACID, BETAINE, POTASSIUM Alcohols and Chemical from Biomass' on Nov. 10-12, SULFATE, AND FREE FLOWING DISTILLER'S 5 1986 in Miami Beach, Fla. The process there disclosed DRY GRAIN AND SOLUBLES OR A SOLID includes a very precise sequence of operations including FERTILIZER THEREFROM ultrafiltration (organic membranes with pore size of <0.1 microns), pH adjustment, filtration, ion exclusion, RELATED APPLICATIONS ion exchange, and carbon treatment. This sequence of This application is a continuation-in-part of copend O operations has not proven to provide a commercially ing application Ser. No. 381,179 filed Jul. 18, 1989, feasible glycerol recovery process. which is, in turn, a continuation-in-part of copending Betaine production is, by way of example, discussed application Ser. No. 136,415 filed 22 Dec. 1987, now in U.S. Pat. No. 4,359,430 to Heikkila et al; Japanese abandoned the priority of which is claimed. Patent No. 51/039625; and Japanese Patent No. 15 80/045067. While the production of betaine from sugar FIELD AND BACKGROUND OF THE beet molasses is a known commercially feasible process INVENTION as described in the above listed patents, it is not known This invention relates to the manufacture of glycerol, to produce betaine from stillage. This is because of a betaine, succinic and/or lactic acid, potassium sulfate, serious fouling of the chromatographic resin by yeast and L-pyroglutamic acid. More particularly the inven 20 cells, microorganisms and other compounds. The manu tion relates to the recovery of the above products as a facture of glycerol, betaine, succinic acid and free flow result of the fermentation and distillation of raw materi ing distiller's dry grain, or the production of both beta als into ethanol and stillage, from which a free flowing ine and glycerol from beet molasses stillage, by pro distiller's dry grain or solid fertilizer is produced. cesses such as those to be described hereinafter has not, The manufacture of each of the products named 25 above by other processes has been known heretofore, insofar as is known to the present inventor, been de and all have commercial uses. Ethanol is used as a bev scribed in any prior patent or publication other than erage, a chemical, and a fuel derived from renewable that which has resulted from the aforementioned prior resources, and is typically manufactured by fermenta ity application. tion and distillation processes starting from biological For the first time, it is now possible to recover betaine materials such as corn, wheat or other grain, sugar cane and/or glycerine from stillage of ethanol fermentations or beets, grapes or other fruit. potatoes, cassava, sweet with sugar beet derivatives. The preparation of the feed sorghum, cheese whey or the like. Glycerol, while with microfiltration and the two chromatographic sepa known to be produced in Small quantities as a by-pro ration steps for the production of pure glycerine and duct of ethanol fermentation and distillation processes 35 betaine are critical. Cross-flow microfiltration with or yeast and yeast extract production, has been manu inorganic membranes followed by enzymatic hydrolysis factured commercially only by processes which have of proteinaceous matter and/or removal of potassium soap as the primary product or which synthesize glyc sulfate crystals in the permeate (if required) will yield a erol from petrochemical feed-stocks. Betaine is conven truly clarified stillage. The clarified stillage may now be tionally produced synthetically or by crystallization of 40 concentrated to a very high solids concentration for the aqueous liquors of beet molasses. Succinic acid is further processing in two chromatographic separation conventionally synthesized from maleic or acetic acid steps, each with its own specific resin, yielding high or produced by means of a highly specific fermentation. purity glycerine and betaine streams. This novel process Lactic acid is conventionally produced by fermentation has several advantages over existing and different meth with Lactobacillus delbruecki, B. dextrolacticus, or 45 ods in use as described in the patents listed above, such similar microorganisms. Potassium sulfate is conven as energy and water savings, reduced capitol invest tionally obtained by reacting sulfuric acid with potas ment, very high solids concentrations, high quality sium chloride. Potassium chloride usually occurs in glycerine and betaine. nature as the mineral sylvine or Sylvite. The processes and apparatus of the present invention Distiller's dry grain, characterized as with (DDGS) 50 contemplate the production of each or all or any combi or without (DDG) solubles, is conventionally produced nation of the products mentioned in a commercially as a by-product of fermentation and distillation pro feasible manner in a fermentation and distillation or cesses. As such the resulting DDG or DDGS is usually similar process. infused with sticky by-products such as glycerol so as to BRIEF DESCRIPTION OF THE INVENTION exhibit poor flowing qualities and be difficult to handle. 55 If the substrate from which distillates are produced is a More particularly, it is an object of this invention to sugar cane or beet material, then the residue is typically produce glycerol as a valuable co-product of a fermen used only as a liquid fertilizer, feed additive or treated as tation process such as one which produces ethanol. In a waste. realizing this object of the present invention, the effi The manufacture of ethanol is sufficiently well ciency of the known ethanol producing fermentation known and the interested reader is referred to the avail and distillation processes is essentially maintained, able literature for descriptions of the basic processes. while an additional valuable product is derived. More The manufacture of glycerol is. by way of example, particularly, ethanol production follows known and discussed in Hildebrandt U.S. Pat. No. 2,169,245; Wal widely published pathways of biochemical reactions. erstein U.S. Pat. No. 2,772,207, to which the interested 65 The present invention contemplates imposing pressures reader is referred. on such pathways in ways which result in enhanced Some suggestion that glycerol night be recovered generation of glycerol and/or other by-products, and from stillage appears in a presentation by Burris entitled permits such enhancement to be achieved with rela 5,177,008 3 4. tively little if any reduction of efficiency in the produc achieving the favorable results of this invention. Ac tion of ethanol. cordingly, the description which follows is to be under Likewise, a further object of this invention is the stood as being a broad, teaching disclosure directed to manufacture of betaine or betaine-HCl and/or L-pyro persons of skill in the appropriate arts, and not limiting glutamic acid as a co-product of a fermentation from a upon the present invention. substrate of Sugar beets or similar materials. Referring now more particularly to FIG. 1 accompa Yet a further object of this invention is the recovery nying this disclosure, there are depicted certain steps of lactic acid and other carboxylic acids from those and apparatus which, in the sequence disclosed herein fermentation processes, such as wet milled corn and after, accomplish the objects of this invention. Certain certain wine fermentations, where lactic acid is pro O steps and apparatus, being well known to those having duced in substantial quantities. skill in the relevant arts, have not been shown in detail Another object of this invention is the production of but will be described for the reader. distiller's dry grain with or without solubles or a solid It is known that the formation of ethanol in a fermen fertilizer premix from a fermentation/distilation process tation process with yeast cells or other microorganisms that is so free of sticky by-products as to be essentially 15 is growth associated and that the formation of glycerol free flowing and thus easier to handle. and succinic acid is interrelated. More specifically, in In its most general sense, fermented mash is distilled the Embden-Meyerhof pathway, NADH from triose in a stripping column with the vaporized ethanol being phosphate oxidation exceeds the rate of acetaldehyde removed from overhead. The remaining stillage is then reduction, thus accounting for normal glycerol forma clarified by centrifuging (if required) followed by mi 20 tion when the cell starved for ATP from glycolysis crofiltration. The microfiltration step, in which parti shifts excess NADH to the reduction of dihydroxyace cles in the range of 0.1 to 10 microns are separated from tone phosphate to glycerol. Additional NADH is sup the stillage, is the key to the recovery of glycerol, beta plied through the Kreb's citric acid cycle. As used ine and by-products in such quantities as to be economi herein, NADH refers to nicotinamide adenine dinucleo cally feasible. Earlier attempts (Burris) to recover glyc 25 tide and ATP to adenosine triphosphate. In a conven erol had suggested ultrafiltration (separation of particle tional well run fermentation process without the recy sizes of less than 0.1 microns) combined with other cle of stillage, some 48 grams of ethanol, 4.0 grams of operative steps, however, due to fouling of ultrafiltra glycerol, 0.6 gram of succinic acid, and small quantities tion membranes, insufficient quantities of glycerol re of lactic acid are formed per 100 grams of reducing sulted to make the process economically feasible. The 30 Sugar consumed. Ethanol producers using a corn wet unexpected result of microfiltration with inorganic milling process generally have substantial quantities of membranes is that, while the stillage is truly clarified, lactic acid present in their fermented mash, as do certain the subsequent recovery of by-products such as glyc wine and other fermentation. erol results in greatly enhanced quantities thereof, mak Turning now to the drawing, regardless of the raw ing its recovery for the first time commercially feasible. 35 material, a fermented alcoholic mash is prepared with Depending on the raw material, the separated clari yeast cells and/or other microorganisms. Whether the fied liquid is subjected to further processing by partial enhancement of glycerol and/or succinic acid is the softening (if required), concentration, enzymatic hydro goal must first be determined in order to properly con lysis of proteinaceous matter, removal of potassium trol the fermentation process. During cell growth, the sulfate crystals, one or more chromatographic separa formation of succinate is high, but during anaerobic tion steps (with different resins where more than one fermentation succinate formation is low. Hence, varia separation step is involved), concentration, and purifi tions in the cell growth fermentation process will per cation to produce glycerol, betaine, L-pyroglutamic mit some degree of control over the ratio of glycerol/- acid, succinic acid, lactic acid, and/or potassium sulfate succinic acid ultimately produced. Further, depending in economically acceptable quantities. Further, the re 45 on the raw material and/or process conditions used for sulting solids are freer of sticky by-products and thus fermentation, betaine, L-pyroglutamic acid, lactic acid more free flowing and easier to handle. and other carboxylic acids may be recovered in suffi cient quantities to be economically feasible. BRIEF DESCRIPTION OF THE DRAWING Regardless of the raw material, after fermentation the Some of the objects of the invention having been 50 next step is normally distillation, preferably in a strip stated, other objects will appear as the description pro ping column, accompanied by overhead removal and ceeds, when taken in connection with the accompany collection of the ethanol vapors. The remaining still ing drawing, in which: bottoms or stillage then contains all or any of the by FIG. 1 is a schematic representation of the flow of the product components described hereinabove. The fur materials in the processes and apparatus of the present 55 ther processing will determine which of the by-pro invention is shown; and ducts are recovered. FIG. 2 is a schematic representation similar to FIG. 1 The first step after distillation, regardless of the by except illustrating the flow of materials in a system products to be recovered, is the clarification process, recovering glycerol and betaine. which may begin with a centrifuging pretreatment with or without chemical treatment. In some cases, a protea DETAILED DESCRIPTION OF THE se(s), a protein digesting enzyme, is added in the pre INVENTION treatment to break down peptides and proteins, which While the present invention will be described more would tend to clog subsequent filtering membranes. fully hereinafter with reference to the accompanying Following pretreatment, if any, the stillage goes drawing, in which a preferred embodiment of the pres 65 through the step of cross-flow microfiltration with inor ent invention is shown, it is to be understood at the ganic membranes. Microfiltration, which is defined outset of the description which follows that persons of elsewhere in the disclosure as the subjection of the skill may modify the invention here described while still stillage to cross-flow microfiltration with a ceramic or 5,177,008 5 6 inorganic membrane having pore sizes in the range of of stillage and adjustment of pH to 5.0 using NaOH. 0.1 to 10 microns separates the stillage into retentate and Comparing the two batches, yields were as follows: permeate, and is the critical step to producing a truly clarified stillage and the recovery of the by-products in economically feasible quantities. Grams/100 Grams of The retentate, containing the larger solid particles, Reducing/Sugar(RS) goes to fertilizer or animal feed processing. The perme Glycerol Succinic Acid ate, depending upon the raw material used, may have to Free Cells 3.38 0.67 be softened to prevent fouling of the chromatographic Innobilized 4.09 0.87 separation resins used downstream. The permeate is 10 then concentrated to as high a solids concentration as Other process parameters which are contemplated as practicable (50–75%). being subject to adjustment in accordance with this The concentrated permeate is then either directly invention include yeast cell concentration and DE or passed on to chromatographic separation (preliminary carbohydrate concentration. As yeast cell concentra to recovery of either glycerol, betaine, succinic acid, 15 tion and carbohydrate concentration rise, production of L-pyroglutamic acid or lactic acid) or is first subjected glycerol and succinic acid are enhanced. These charac to a crystallization operation (for recovery of potassium teristics are illustrated in the following example: sulfate from beet stillage). If the by-product is to be glycerol, the chromatographic separation used is ion EXAMPLE 2 exclusion and is followed by ion exchange, evaporation A mash was prepared from ground whole milo and to a concentration of 80-85% glycerol, further distilla fermentation started at pH 4.9 and DE 27 using free tion into almost pure glycerol, and refining into yeast cells and at a temperature of 33 Celsius. Fermen USP/CP or ultra-pure glycerol. tation was performed in batches, without stillage recy The by-product stream from the aforementioned cle. Yields, related to yeast cell and carbohydrate con chromatographic separation step goes to animal feed 25 processing or to a second separation step, which may be centration, were as follows: chromatography (for betaine where the raw material is sugar beets) and/or physico-chemical separation for the Yeast cell production of succinic acid, lactic acid, L-pyroglutamic concentration grams/100 grams RS acid and/or betaine (where the raw material is sugar 30 per 10 m) DE Glycerol Succinic Acid beets). Where corn is the raw material for a wet milling 100 27 3.03 0.49 process, the economically feasible recovery of lactic 300 27 3.07 0.52 500 27 3.19 0.61 acid is possible through the second chromatographic 500 46 3.37 0.64 separation step. With sugar beets, betaine and L-pyro 500 90 50 0.88 glutamic acid may be recovered as well. In such case, 35 the first chromatographic separation yields glycerol and betaine. These are separated in the second chromato These results reflect enhanced glycerol and succinic graphic step and each product is purified, concentrated. acid production following from increased concentra and refined. Except for betaine, sugar cane produces the tion of yeast cells and carbohydrates during fermenta same products as Sugar beets. 40 tion. The first process parameter to be addressed for en Still other process variables which are contemplated hanced glycerol and/or succinic acid formation during by this invention as being optimized for the production fermentation relates to the form of yeast used in the of the desired products while maintaining ethanol pro fermentation process. It has been determined that a duction include osmotic pressure during fermentation; properly immobilized organism will enhance and in 45 concentration of dissolved carbon dioxide; pH; temper crease production of glycerol and succinic acid. These ature; selection of the microorganism used; the mode of results are achieved where the yeast is in a stable ionic fermentation; and the formulation and preparation of and high density matrix, as illustrated in the following fermentation media. More precisely, increased osmotic example. pressure from recycling stillage, increased solute con 50 centration, and/or increased temperature increases pro EXAMPLE 1 duction of glycerol and succinic acid, as does increased A mash prepared of ground whole corn was sub dissolved carbon dioxide. Yeast cells, as most microor jected to jet cooking for two minutes at 149 C. and ganisms, are able to regulate its internal pH quite effec then to liquefaction at a pH of 6.3 to a dextrose equiva tively within a range of mash pH of from about 3 to lent (DE) of 20.3, and to saccharification to DE 36 at 55 about 7, and thus the effect of process variations in pH pH 4.5. Immobilized yeast cells were prepared by mix may appear minimal. It has been determined, however, ing a 1.5 weight percent sodium alginate solution with that production of glycerol and succinic acid is en the preferred ratio of hydrated yeast cells and sterilized hanced where an essentially constant pH is maintained sand. The resulting slurry was poured through a 12 during the first half of the fermentation step (when the mesh screen into an aqueous solution of 0.5M CaCl2 and bulk of glycerol and succinic acid are produced) by the 1.5 weight percent glucose at pH 4.6 and ambient tem addition of a suitable alkali such as sodium carbonate. perature. On contact with the calcium chloride, the The fermentation media, or mash, characteristics will drops formed beads which, after 24 hours in a refrigera affect the production of glycerol and succinic acid due tor at 4 Celsius, gelatinized into firm beads with diame to the interacting effects of the raw material itself, the ters of 2-4 mm. The mash was then fermented in two 65 concentration of any liquefying enzyme, the ratio of batches at 34° Celsius with free and immobilized yeast fermentable sugars to nonsugars, the type of nonsugars cells at concentrations of 5.0 grams per liter. Fermenta present, and the nutritional requirements of the particu tion was performed in a batch process with no recycling lar fermentation microorganism chosen. 5,177,008 7 8 Proper selection of the parameters described above choice between batch and continuous processes, while will result in enhanced production of glycerol and suc the other parameters are as identified above in the de cinic acid as contemplated by this invention. The fol scription of Example 3. lowing examples include illustrations of variation in the It will be observed that parameters may be found at various parameters and the effects on glycerol and suc- 5 which the production of glycerol and succinic acid cinic acid production of those variations. drop below the maximized levels. However, the maxi EXAMPLE 3 mized levels of production of the by-products sought by A mash prepared from ground whole corn was sub the present invention is attained without significant jected to jet cooking for 3 minutes at lis2 Celsius, was 10 impairment of ethanol production. liquefied to DE 20.6 and partially saccharified. Batches EXAMPLE 5 of the mash were then fermented and distilled using In order to illustrate other processes without charac process parameters as set forth in the following table, terizing the additional process as achieving optimal with yields as noted. production of glycerol and succinic acid, a clarified 5 wood hydrolyzate was prepared from yellow pine and Process Batch processed by batch fermentation with pH held constant Paraneter A B C D for 25 hours, without recycling of stillage and with YCC 1.2 3. 9.0 26.5 parameters and yields as follows: DE 33.2 56.3 78.7 78.7 Recycle O 38.3 44.1 74 20 Temperature 30 34 35 35 Process Batch pH 4.5 5.5 6.0 5.0 Parameter A. B C Head at. 1.7 2.3 1.2 Yeast type free immob, immob. immob. YCC 5.0 40.0 40.0 Time 58 39 12 9 RS 54.3 54.3 74.1 Yields 25 Temperature 3. 33 34 grams/100 grams RS Head af. 0.3 1.2 Ethanol 44.9 44.1 42.0 44.7 Yeast type free immob. immob. Glycerol 4.8 5.8 83 2.3 Fermentation batch batch batch Succinic acid 0.6 0.7 1 .4 Time 68 43 41 pH 5.0 5.5 5.0 30 Yields In the table, YCC refers to yeast cell concentration in grams/100 grams RS grams per liter with approximately 100 cells per gram. Ethanol 29.4 34.5 40.4 DE refers to dextrose equivalent after saccharification. Glycerol 3.4 3.9 6.9 Recycle refers to the percentage of recycled stillage in Succinic acid 0.5 0.8 1. the mash being processed. Temperature is the tempera- 35 ture of fermentation in degrees Celcius. The reference In accordance with this invention, a fermented mash to pH is to the value at which pH was maintained dur prepared in accordance with any of the above examples ing the first half of the fermentation by the addition of is then further processed to yield pure glycerol derived sodium carbonate. The "Head" was head pressure in from natural sources (and thus of kosher purity) and/or psig. Time is in hours for fermentation. 40 succinic acid. As a result of the further processing, the Considering the tabulated examples together, it is end residue solids may be dried to yield DDG and noted that production of glycerol and succinic acid was DDGS and/or fertilizer premix which is free flowing substantially enhanced with little adverse effect on etha and more readily handled than are the similar products nol production. of other prior processes, due to the removal of the glyc EXAMPLE 4 45 erol. Generally, the first further processing step is distilla A mash was prepared from clarified and pasteurized tion of the fermentation to produce ethanol. Such distil blackstrap molasses, and batches of the mash were then lation may be by use of a stripping column capable of fermented and distilled using process parameters as set handling a solids containing stream. The still bottoms or forth in the following table, with yields as noted. 50 stillage is then centrifuged (if required) and the centrate processed further in a clarification step, removing the Process Batch dispersed solids to obtain a (sparkling) clear liquid. Parameter A B C D E Clarification is accomplished with (cross-flow) mi YCC 1.0 3.0 18.2 32.0 20 crofiltration systems containing ceramic or mineral RS 184 84 192 200 200 55 membranes. In this process particles in the range of Recycle 0 24.7 43.0 37.9 48.4 Temperature 30 34 34 35 35 0.1-10 microns, depending on the membrane selected Head atf. 0.9 1.8 2.1 1.2 are separated from the thin stillage. High and stable Yeast type free free immob. innob. in mob. fluxes may be obtained through computer controlled Ferinentation batch batch batch cont. batch backflushing and proper membrane selection. These Tine 51 27 10 6 12 60 pH 4.5 5.0 6.0 5.5 5.0 new microfiltration membranes are known as such and Yields are commercially available from known suppliers. Such grams/100 grams RS known apparatus may be incorporated into the overall Ethanol 48.3 47.8 43.9 46.4 45.1 apparatus which practices the processes of this inven Glycerol 3.7 4.3 8.4 5. 0.9 tion. A chemical clarification process may proceed by Succinic acid 0.5 0.6 1.0 0.8 1.2 65 taking up to 20 percent of the stillage and liming it to a pH of 9.0 to 12.0 while at or near boiling. The remain In the table, RS refers to reducing sugar concentra der of the stillage is adjusted to a pH range of 4.5 to 7.5 tion in grams per liter and "Fermentation" refers to a with sodium hydroxide, calcium hydroxide and/or so 5,177,008 9 10 dium carbonate at temperatures as high as practicable. concentrated through evaporation to 73 weight percent The two portions are then mixed and a precipitate of solids, while it still behaved like a Newtonian fluid. It salt forms, the separation of which is improved by the was fed at about 60 percent solids to an IWT Adsep addition of polyelectrolytes, followed by centrifuga system consisting of a single three inch I.D. column tion. Depending upon the raw material following mi with a bed height of 62.25 inches of IWT SM-51-Na crofiltration or chemical clarification is a (partial) soft resin. The concentrate was fed at a rate of 2 ening step: mainly for the reduction of the divalent GPM/square foot, with 20% feed pulse at 1.442 liters/- cation levels of calcium and magnesium. This will pre pulse. The glycerol containing effluent was passed vent the plugging and fouling of the downstream ion through an IWT mixed bed ion exchange unit to im exclusion resin by salt deposits of divalent cations due to 10 prove purity; then adjusted to pH 7.0 using NaOH: potential process upsets which would considerably re then, using Mazzoni equipment, concentrated by evapo duce the operating efficiency. As the stillage is clarified, ration to 83.1 weight percent glycerol; and distilled and it may be passed to and through an evaporator to re refined to a CP/USP grade glycerol of high quality. move as much water as possible and effect as high a Constituents in the material at stages in the process solids concentration as is practicable. Due to proper 15 were as summarized in the following table showing clarification, the overall heat transfer coefficient in weight distributions. volved will be considerably improved over thin stillage which has not been clarified, while the fouling of heat transfer surfaces will also be minimized. Clarified The clarified and concentrated stillage is passed to an 20 Conc. Adsep Final ion exclusiof apparatus such as that available from Illi Constituent Stillage Stillage Effluent Product Total solids 7.37 5.01 1.2 Trace nois Water Treatment Company of Rockford, Ill. and Protein 2.36 07 Trace - which contains a suitable resin material such as IWT's Carbohydrates 1.9 0.38 0.03 - SM-51-Na resin or other similar resin available from Fat 0.007 0.003 0.00 - Dow Chemical as Dowex 50-WX8. As the material 25 Ash 0.84 0.77 0.09 - passes through the ion exchange apparatus, glycerol is Lactic acid 1.42 1.32 0.05 Trace Succinic acid 0.09 0.08 0.006 - "retained' while other ionic constituents are passed into Other 0.343 0.306 0.026 Trace an effluent stream. Recovery efficiencies are in the Glycerol 0. 0.96 0.94 0.92.4 range of from about 80% to about 98%, and the purity Water 92.63 8.9 5.687 0.007 of the glycerol recovered is in a range of from about 30 Total 100.00 3.92 8.04 0.93 Percent 1.01 6.90 5.19 99.25 80% to about 90%. The apparatus may be a simple or Glycerol multiple column system used as a pulsed bed or a simu Na, ppm 10,700 740 lated moving bed. Recycling may be used to maintain or K, ppm 4.500 70 increase product purity and/or recovery efficiency. Mg, ppm 960 70 Condensate as is from any evaporators used in the appa 35 Ca, ppm 240 4. ratus may serve as desorbent, with desorbent to feed Mn., ppm 90 2 ratios in the range of from about 1.6 to about 3.0. Such a column is in ionic equilibrium and requires no regener A further example of the recovery of ethanol, glyc ation. Effluent from a glycerol recovery ion exclusion erol, succinic acid and lactic acid follows: apparatus, after concentration, may be passed through a 40 comparable apparatus for recovery of succinic acid. EXAMPLE 7 The dilute succinic acid product is concentrated in an A mash prepared of ground degerminated yellow evaporator and purified through crystallization. The dent number two corn was cooked and liquefied to a resulting by-product stream of the ion exclusion step, dextrose equivalent (DE) of 21.3. The mash was then before or after succinic acid recovery, is ideal for use as 45 partially saccharified and subsequently fermented with a backset in the fermentation. It is a "clean' stream, co-immobilized gluco-amylase and Saccharomyces ce which will increase osmotic pressure levels as well as revisiae yeast with the following process parameters reduce process water requirements. and yields: The glycerol stream recovered from the ion exclu sion apparatus and process may be further purified in a 50 mixed bed ion exchanger and then concentrated and Process Batch purified to any desired grade. Such concentration and Parameter A B C purification may, for example, be accomplished by the YCC O7 118 15 DE at start of ferm. 82 84 2 use of an energy efficient vacuum/steam multiple effect Recycle 83 84 40 evaporator, and distillation and refining unit such as 55 Temperature 38 39 34 those available from G. Mazzoni SpA of Italy, with the pH 6.8 7.2 5.0-3.9 more concentrated glycerol being deodorized, Head 15.6 16.0 at OS. Time 7.4 7.9 49 bleached, filtered and/or polished as desired. Yields As a further example, the production of glycerol and grams/100 grams RS succinic acid without specific preparation of a stillage Ethanol 43.9 43, 47.9 having enhanced levels of those constituents is believed Glycerol 17.0 20.2 9. valuable. Succinic acid .8 1.9 0.8 Lactic acid trace trace 11.9 EXAMPLE 6 Stillage from a facility for the production of ethanol 65 The reference to pH is to the value at which pH is from wet milled corn was centrifuged and the thin stil maintained during the first two thirds of the fermenta lage subjected to microfiltration in a ceramic membrane tion by the addition of sodium carbonate in the process unit. The clear permeate was partially softened and then of column A and sodium hydroxide/sodium sulfite in 5,177,008 11 12 the process of column B. The "Head" was fermenter of from about 80% to about 98%, and the purity of the head pressure in psig, Time is in hours for fermentation. recovered glycerol is in the range of from about 80% to The process of column C differs from those of co about 98% as well. umns A and B. The process of column C was based on The chromatographic separation apparatus may be a the production of ethanoi from wet milled corn; fer single or multiple column system used as a pulsed bed or mentation was continuous, and pH was permitted to a simulated moving bed in a continuous process. The vary over time from a starting pH of 5.0 to an ending condensate from any evaporators used in the process pH of 3.9. may be used as the desorbent, thus minimizing make up Considering the tabulated examples together, it is water requirements. Desorbent to recovered glycerol noted that production of glycerol was substantially 10 ratios are in the range of from about 10 to about 25. enhanced with relatively little adverse affect on ethanol Such a system is in ionic equilibrium and does not nor production. It is possible to further enhance glycerol mally require regeneration. The by-product stream, and succinic acid production, although ethanol produc containing succinic and lactic acids, may be concen tion falls substantially as such further enhancement is trated to as high a solids content as practicable and the achieved. 15 succinic and lactic acids separated in a further chro In the processes of this Example 7, the fermented matographic separator using either acid retardation or mash is distilled to strip off ethanol. The bottons or ion exclusion. The succinic acid stream is concentrated whole stillage is clarified to obtain a clear liquid. In the and the acid is recovered through crystallization. Sini preferred process, as previously described, cross flow larly, lactic acid may be recovered at this point by stan microfiltration systems with inorganic membranes hav 20 dard processes. Ion exchange of the product streams ing pore sizes in the range of from about 0.1 microns to will in most cases improve product purity. Depending about 10 microns are used to remove particulate matter. upon the resin, starting substrate and operating condi Such inorganic membranes for the first time allow tions used, betaine and glycerol may exit the chromato proper stillage clarification. Hot stillage, either as re graphic separation together. It is then necessary to use ceived or after centrifugation and/or filtration to re 25 the following (smaller) chromatographic separation to move coarse particles, may now be processed. Prefera produce a pure betaine stream from which betaine may bly, computer controlled backflushing (at high pressure be recovered with standard processes. Using a resin if necessary) will allow for high on-line stream factors such as IWT-AM-63, excellent separations were ob for the microfiltration modules and will in most cases tained. Over 98 percent of the glycerol and over 92 eliminate the need for (harsher) chemical cleaning. The 30 percent of the betaine were recovered making it simple feed may be pretreated chemically to produce a floc, to produce pure products. The desorbent may be con which under controlled conditions, will form a "dy densate produced in the overall process. In a large scale namic membrane' layer and improve the clarification. test at 60° C., the desorbant used was 5.7 pounds of Known filtration apparatus having the characteristics water per pound of betaine and 13.6 pounds of water recited may be incorporated in the overall apparatus 35 per pound of glycerol, while 0.81 pounds of betaine per which is used in practicing this invention. minute and per square foot and 0.34 pounds of glycerol Microfiltration yields a concentrate or retentate per minute and per square foot were obtained. which is further processed into DDG or DDGS, a feed The glycerol product stream is concentrated in dou product for animals or a component for human food ble effect LTV evaporators to approximately 85% dry products, or a fertilizer base to which may be added the solids. Feed forward systems employing a thermocorn by-product stream from chromatographic separation pressor with high pressure steam and feed backward processes described hereinafter. The microfiltration systems using greater quantities of lower pressure steam permeate may, if necessary, be softened to remove diva may be used. The concentrated crude glycerin may be lent cations which could otherwise foul the down neutralized before it is fed into the rectifying section of stream chromatographic separation resin(s). 45 a high efficiency distillation column. Through evacua The clarified stillage is next concentrated to as high a tion and direct steam injection the column partial pres solids concentration as practicable. Due to the clarifica sure is kept low to minimize glycerol decomposition. tion, the overall heat transfer coefficients involved have Glycerol leaves the evaporators for condensors, and been improved while scaling of heat exchange surfaces then is deodorized with steam and bleached with granu has been minimized. Where the fermentation substrate is SO lar activated charcoal. Consumption of charcoal is mini a sugar beet product, cooling and/or addition of sulfu mized due to the already relatively purified state of the ric acid will bring about the formation of potassium glycerol feedstock. The product then passes through sulfate, which may be recovered through crystallization polishing filters and a cooler to produce ultra pure glyc to yield yet another valuable by-product. erin. The evaporation, distillation and refining equip Chromatographic separation of the clarified, concen 55 ment are known, as such, and is available with the inclu trated stillage then follows. In a preferred method and sion of design improvements over conventional glyc generally as disclosed in the priority application identi erin apparatus from G. Mazzoni SpA of Italy. fied above, the material passes through an ion exclusion It is also contemplated for this invention that glyc apparatus containing a suitable resin. Glycerol, as a erol, succinic acid, betaine, L-pyroglutamic acid, potas non-ionized compound, is unaffected by the Donnan sium sulfate and a solid fertilizer may be produced from potentials and distributes itself freely inside the aqueous beet molasses stillage without the specific preparation pore structure of the resin beads, while the ionic com of a stillage having enhanced levels of glycerol and pounds pass around the beads and exit the apparatus succinic acid. Such a process is illustrated by the fol first. Ion exclusion and exchange resins may be kept in lowing: the potassium monovalent form, which will maximize 65 the separation between ionic and nonionic components EXAMPLE 8 as well as improve formation of potassium sulfate. At As described in FIG. 2, stillage from a plant produc tainable glycerol recovery efficiencies are in the range ing ethanol from sugar beet molasses, was processed 5,177,008 13 14 into ultra-pure glycerine and betaine-HCl in a continu ous process. Enhanced formation of glycerol was not -continued pursued during the fermentation. The hot stillage was Total Suspended clarified in a cross-flow microfiltration unit with 0.2 Solids Solids Glycerol Betaine After Second micron alpha aluminum oxide membranes. The perme Chromatographic ate obtained was treated enzymatically at 50 C. to Separation hydrolize proteinaceous matter and consequently evap Betaine Stream 23.7 0.5 20.9 orated to a solids concentration of over 66 wt. %, After Second Through cooling and crystallization in a malaxeur, po Chromatographic tassium sulfate crystals were formed which through 10 Separation centrifugation, washing and drying were recovered as a technical-grade K2SO4, which is more valuable then In the drawing and specifications, there has been set leaving it in the remaining stillage (fertilizer). The cen forth a preferred embodiment of the invention and, trate was then fed to the first chromatographic separa although specific terms are used, the description thus tion system in which a mixture of betaine plus glycerol 15 given uses terminology in a generic and descriptive is separated from the rest. This ion exclusion system sense only and not for purpose of limitation. used a strong acid cation exchange resin in the potas What is claimed is: sium form with a mean particle size of approximately 1. A continuous process for recovering glycerol from 375 micron and a moisture retention capacity of approx stillage produced from the fermentation and distillation imately 52.5% (H+ form; IWT SM-51). The product 20 of such biological materials as corn, wheat, other grains, stream contained 36.3% total solids with approximately sugar cane, sugar beets, grapes, other fruit, potatoes, 92% purity in terms of glycerine plus betaine. Water cassava, Sweet sorghum, and the like which results in was used as the desorbent. This product stream was ethanol and said stillage, said continuous process com next concentrated to 75% total solids and fed to a sec prising the steps of ond, considerably smaller chromatographic system, 25 a) clarifying the stillage by subjecting the stillage to a which contained a polystyrene strong base anion ex cross-flow microfiltration process utilizing inor change gel resin in the sulfate-form. Its mean particle ganic membranes having pore sizes in the range of size is approximately 350 micron and its water holding 0.1 to 10 microns. capacity between 41-46%. Both resins used meet all b) passing the clarified stillage through an ion exclu requirements for use in food applications (FDA Regula sion material for separating chromatographically tion Title 21, Subpart A, Section 173.25). Water was glycerol from other constituents of the clarified again the desorbent. This second chromatographic sep stillage, and aration step did yield a glycerine stream with a purity of c) purifying the separated glycerol. 97.6% (after mixed-bed ion exchange) and a betaine 2. The process according to claim 1 wherein the step stream with a purity of 88.2%. The glycerine stream 35 of clarifying further comprises initially centrifugally was easily further processes into ultrapure glycerine separating solids from liquid constituents prior to sub with G. Mazzoni SpA equipment. The betaine stream jecting the stillage to microfiltration. was further processed into pure betaine and betaine 3. The process according to claim 1 wherein when HCl. Overall recovery was 88.5% for glycerine and sugar beets are used as the stillage producing material, 93.2% for betaine. 40 the clarified stillage from step (a) is enzymatically The remaining stillage was combined with the by treated to hydrolize proteinaceous material. product stream from the first chromatographic separa 4. The process according to claim 1 wherein when tion step, the retentate from the microfiltration step as sugar beets are used as the stillage producing materials, well as the by-product streams from glycerine purifica the clarified stillage is concentrated to 50-75% solids tion and then concentrated and dried into a solid fertil 45 and the resulting potassium sulfate crystals are re izer premix or feed additive. moved. In the second chromatographic separation step, an 5. The process according to claim 1 wherein the other resin used also resulted in the production of pure permeate from the microfiltration step is concentrated glycerine and betaine streams. This resin is a strong acid to as high a solids concentration as practicable before cation exchange resin in the calcium-form with a mean 50 passing through said ion exclusion material. particle size of 350 micron and a moisture retention 6. The process according to claim 1 wherein said capacity (H+ form) of 57.5-61.0%. Succinic acid and purifying step comprises the steps of ion exchange, L-pyroglutamic acid were not recovered. evaporation to a concentration of 80-85% glycerol, The concentration of key components in weight per further distillation and refining into glycerol having a cent at intermediate stages was as follows: 55 purity of at least 99.7%. 7. The process according to claim 1 wherein said stillage is produced by the steps of: Total Suspended a) preparing a mash from biological materials; Solids Solids Glycerol Betaine b) fermenting said mash with sufficient yeast to pro Stillage 7.5 1.0 0.7 1.5 60 Microfiltration 6.5 0.7 1.5 duce a fermented mash having at least about 9 Permeate grams of glycerol and 40 grams of ethanol per 100 Evaporator 60.0 6.3 13.5 grams of reducing sugar in the mash; Concentrate c) distilling the fermented mash to produce ethanol in After First 36.3 10.6 22.7 said stillage. Chromatographic Separation 65 8. The process according to claim 7 wherein said Evaporator 75.0 22.0 47.0 yeast comprises immobilized yeast cells. Concentrate 9. The process according to claim 7 wherein said step Glycerol Stream 38.2 37.3 of fermenting said mash comprises the step of mixing 5,177,008 15 16 with said mash yeast cells in a concentration in excess of glutamic acid, and said second stream is subjected to 100 grams per liter. further chromatographic separation stages to separate 10. The process according to claim 7 wherein said each, all and any combination of the other products mash is so prepared as to have a dextrose equivalent of from the remaining products. at least about 80. 5 22. The process according to claim 14 wherein said 11. The process according to claim 7 wherein the pH fermentation, distillation, clarification, chromato of the mash is maintained substantially constant during graphic separation, and purification are all a part of a the first two-thirds of said fermentation process. continuous process. 12. The process according to claim 7 wherein the step 23. A continuous process for recovering at least two of fermenting said mash comprises adding sufficient O of the group containing glycerol, betaine, succinic acid, yeast to produce a fermented mash having at least about lactic acid, L-pyroglutanic acid from stillage produced 15 grams of glycerol and 40 grams of ethanol per 100 from the fermentation and distillation of such biological grams of reducing sugar in the mash. materials as corn, wheat, other grain, sugar cane, sugar 13. The process according to claim 7 wherein said beets, grapes, other fruit, potatoes, cassava, sweet sor steps of clarifying, chromatographic separation, and 15 ghum, and the like which result in ethanol and said purifying are a continuous process. stillage, said continuous process comprising the steps of: 14. A continuous process for recovering glycerol and a) clarifying the stillage produced from the distilla betaine from stillage produced from the fermentation tion of the fermented mash by subjecting the still and distillation of sugar beets which results in ethanol lage to a cross-flow microfiltration process utiliz and said stillage, said continuous process comprising the 20 steps of: ing inorganic membranes having pore sizes in the a) clarifying said stillage by subjecting the stillage to range of 0.1-10 microns; a cross-flow microfiltration process utilizing inor b) passing the clarified stillage through a succession ganic membranes having pore sizes in the range of of ion exclusion apparatuses for chromatographi 0.1-10 microns; 25 cally and/or physico-chemically separating each b) subjecting the clarified stillage to a first chromato product from the other constituents of the clarified graphic separation by passing the clarified stillage stillage; and through an ion-exclusion apparatus for separating c) purifying the separated product. glycerol and betaine as a mixture from other con 24. The process according to claim 23 wherein when stituents of the clarified stillage; Sugar beets are used as the stillage producing material, c) subjecting the glycerol/betaine mixture to a sec the clarified stillage from step (a) is enzymatically ond chromatographic separation by passing the treated to hydrolize proteinaceous material. mixture through a second ion exclusion apparatus 25. The process according to claim 23 wherein when in which the glycerol is separated from the betaine; Sugar beets are used as the stillage producing material, and 35 the clarified stillage is concentrated to 50-75% solids d) purifying the separated glycerol and betaine. and the resulting potassium sulfate crystals are re 15. The process according to claim 14 wherein said moved. step of clarifying further comprises initially centrifu 26. Glycerol manufactured in accordance with the gally separating solids from liquid constituents prior to process of claim 1. subjecting the stillage to microfiltration. 27. Glycerol and betaine manufactured in accordance 16. The process according to claim 14 wherein the with the process of claim 14. clarified stillage from step (a) is enzymatically treated to 28. Glycerol, betaine and potassium sulfate manufac hydrolize proteinaceous material. tured in accordance with the process of claim 14. 17. The process according to claim 14 wherein the 29. Glycerol betaine, and L-pyroglutamic acid manu clarified stillage is concentrated to 50-75% solids and 45 factured in accordance with the process of claim 14. the resulting potassium sulfate crystals are removed. 30. Glycerol and one of the group consisting of beta 18. The process according to claim 14 wherein the ine, succinic acid, lactic acid, and L-pyroglutamic acid glycerol/betaine stream from the first chromatographic manufactured in accordance with the process of claim Separation step is concentrated to approximately 75 wt. 23. percent before passing onto the second chromato 50 31. A continuous process for the recovery of betaine graphic separation step. from beet stillage produced from the fermentation and 19. The process according to claim 14 wherein the distillation of sugar beets which results in ethanol and glycerol stream and the betaine stream which issue from Said beet stillage, the continuous process comprising the the second chromatographic separation step are each steps of: subjected to ion exchange, further concentration, and 55 a) clarifying said stillage produced from the distilla purification by distillation and refining into glycerol and tion of fermented sugar beet mash by subjecting the crystallization into betaine-HCl or betaine. stillage to a cross-flow microfiltration process uti 20. The process according to claim 14 wherein the lizing inorganic membranes having pore sizes in the permeate from the clarification step is subjected to a range of 0.1-10 microns; crystallization process resulting in potassium sulfate b) subjecting the clarified stillage to chromatographic crystals and a permeate containing glycerol/betaine separation by passing the clarified stillage through which is passed on to said first chromatographic separa an ion exclusion apparatus for separating betaine tion step. from other constituents of the clarified stillage; and 21. The process according to claim 14 wherein said c) purifying the separated betaine. first chromatographic separation separates essentially 65 32. The process according to claim 31 wherein the glycerol and betaine into a first stream and a second step of clarifying further comprises initially centrifu stream contains other products including at least one of gally separating solids from liquid constituents prior to Such products as succinic acid, lactic acid and L-pyro Subjecting the stillage to microfiltration. 5,177,008 17 18 33. The process according to claim 31 wherein the to as high a solids concentration as practicable before passing through said ion exclusion material. clarified stillage from step (a) is enzymatically treated to 36. The process according to claim 31 wherein said hydrolize proteinaceous material. purifying step comprises the steps of ion exchange, 5 evaporation to a concentration of 80-85% glycerol, 34. The process according to claim 31 wherein the further distillation and refining into glycerol having a clarified stillage is concentrated to 50-75% solids and purity of at least 99.7%. the resulting potassium sulfate crystals are removed. 37. The process according to claim 31 wherein said clarification, chromatographic separation, and purifica 35. The process according to claim 31 wherein the O tion are all a part of a continuous process. permeate from the microfiltration step is concentrated sk k xk k k