GB2211195A

GB2211195A - Process for treating a fermentation wort

Info

Publication number: GB2211195A
Application number: GB8824537A
Authority: GB
Inventors: Jacqueline Lecourtier; Christine Noik; Guy Chauveteau
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 1987-10-20
Filing date: 1988-10-20
Publication date: 1989-06-28
Anticipated expiration: 2008-10-20
Also published as: IN172065B; GB8824537D0; GB2211195B; DE3835771A1; JP2683813B2; FR2621926B1; NO884635L; NO173145C; JPH01153098A; NO173145B; FR2621926A1; NO884635D0; CA1331358C; CN1032674A; CN1029240C

Description

2211195 PROCESS FOR TREATING A FERMENTATION WORT The invention relates to

a process for treating a fermentation wort comprising a polysaccharide in order to increase its filterability. It also relates to the resulting improved wort and to the use of said wort as a thickening agent in enhanced oil recovery.

Polysaccharide worts are obtained through a well known fermentation procegs a micro-organism producing polysaccharide, which for example belongs to the Xanthomonas species for the production of Xanthane, is grown in a nutrient aqueous medium containing a carbon hydrate and more especially glucose.

Xanthomonas Campestris can for example be.used for the production of Xanthane. In order to produce Scleroglucane, Sclerotium Rolfsii can be utilized, and for Schizophyllane, the Schizophyllum Commune fungus will be used.

At the end of the fermentation process. a fermentation wort comprising about 0.5 to 4% by weight of polysaccharide as well as salts, residual nutrient elements, fungus cells or remains and other insoluble compounds are gathered.

The insoluble particles in the raw wort can be removed by filtration. There are still some macromolecules aggregates with a pseudo-plastic behavior which are difficu lt to filter and tend to obstruct the 2 pores of the underground deposits during the enhanced recovery operations.

Numerous solutions have been suggested concerning this paint, as can be seen for example in the considerable patent literature.

BACKGROUND OF THE INVENTION

US Patent 3,355,447 for example suggests to heat a Xanthane wart and to filter it. US Patent 4,299,825 proposes heating and then ultrafiltering the wart in order to obtain a clarified and concentrated wart. Patent EP 0049 012 suggests to perform an ultrafiltratiDn, with or without any L-nzymatical treatment, in order to obtain a concentrated Xanthane solution.

Patents EP 0140724 and 0140725 suggest a heating followed by a concentration throunh ultrafiltration and, possibly, diafiltration. it is said that the ultrafiltration process has no effect- on the filterability or the injectability of the Xanthane solutions.

The results of the cited processes are not really performant; therefore, a process allowing to obtain a wart with a good filterability and, above all, a filterability that is stable in time, is necessary.

DETAILED DESCRIPTION OF THE INVENTION

The process according to the invention relative to the treatment of polysaccharides worts respectively comprises A) performing an ultrafiltration with a diaphragm the cut-off zone (Mw) of which is between 10,000 and 100,000 and preferably between 10,000 and 30,000 as for the molecular mass, while letting at least one volume of aqueous phase filter through and adding at least one volume of water (or salted water) to the wort per volume of wort. and gathering the fraction of wort that has not gone through the diaphragm (residue), B) heating the residue obtained in stage A up to at least 600C. for example 60-1300C.

The impurities that have gone through the diaphragm can be rejected.

In the ultrafiltration described above, water flows through the diaphragm with the impurities so that the obtained residue could show a greater polysaccharide concentration than the wort before the treatment. Still this is not the object of the invention and water, preferably salted water, is added in order to maintain for example the same polysaccharide concentration in the wort as before the treatment.'A preferred embodiment even consists in following the ultrafiltration bv progressively adding to the wort at least one volume of 4 water or salted water (for example with 1-100 g/1, expressed in NaCl, of salts of alkaline metals), for example 1 to 10 volumes, preferably 5 to 10 volumes by volume of treated wort, while letting at least one volume of water, for example 1 to 10 volumes, and preferably a volume more or less equal to that of the added liquid, filter through. This can be achieved continuously or discontinuou sly, going through several ultrafiltration cells and/or recycling the solution in the same cell several times. This type of treatment is commonly called diafiltration.

Still, after said diafiltration, the process can be completed with a usual concentration by any means, including concentration ultrafiltration.

The preferred embodiment conditions are described hereunder:

During the ultrafiltration, the polymer concentration in the wort advantageously goes from 5 to g/1, preferably from 15 to 30 g/1. Lower concentrations, for example at least 100 ppm, are also suitable. The choice of the diaphragm is not a determining one and good results have for example been obtained with cellulose acetate, cellulose ether, polyamide, polyolefin, polystyrene and sulfonated polystyrene diaphragms, since the invention is not limited to the use of such or such diaphragm.

The wort that has been subjected to the ultrafiltration advantageously comprises 1 to 100 g/1, preferably 5 to 50 g/1, expressed in NaCI, of one or several salts of alkaline metals.

The wort may have been subjected to a standard pre filtration, for example in order to eliminate the cell residues larger than 20 micrometers or preferably larger than 1 micrometer.

The pH during the ultrafiltration is advantageously selected between 4 and 11 and the temperature ranges for example from 10 to 500C, preferably from 20 to 400C.

During the heating, the polymer concentration can be selected within limits ranging from 5 to 100 g/1, preferably from 15 to 30 9/1. As has been said above, lower concentrations are also suitable.

The optimal heating duration depends an the wanted result and an the nature of the polysaccharide; it most often ranges from 1 to 60 minutes, preferably from 5 to 15 minutes for Xanthane and from 1 to 24 hours for Scleroglucane and Schizophyllane.

The following comparative examples illustrate the working of the process.

EXAMPLE 1

A raw Xanthomonas Campestris fermentation wort has been diluted in order to bring its.concentration to 380 6 ppm by weight; its alkali- metal concentration, expressed in NaCl, has been brought to 5 g/1 by adding sodium chloride.

Three samples of the obtained solution (viscosity at 300C: 2.10-:.'s Pa.s-1.; concentration: 380 ppm by weight) have been taken.

Sample No.1 has been brought up to 1100C for 10 minutes, then cooled down to 300C and subjected to the filterability test.

Sample No.2, according to the invention, has been ultrafiltered at 300C by coming into contact with a cellulose acetate diaphragm with a cut-off zone of 20,000 5 volumes of liquid per volume of sample No.2 are let filter through while the filtered liquid is progressively replaced by the same volume of an aqueous solution with 5 g/1 of NaCl. The obtained residue has been subjected to the same heating and cooling -than sample No.l. It has then been subjected to the filterability test.

Sample No.3 has first been heated and cooled like sample No.1 then ultrafiltered at 300C like sample No.2 and then subjected to the filterability test.

-After the treatments described above, solutions No.1 and 3 both showed a viscosity of 7.10-' Pa.s'. at 300C and solution No.2 had a viscosity of 7.7.10-: Pa.s-1. at 300C.

7 The filterability test consisted in injecting, under low shear rate conditions ( _ = 5 s-l.) and at 300C, the polymer solution through three Millipore filters with an average pore diameter of 5 pm and determining the mobility reduction (R) in the filters according to the filtered volume (V).

Curves Ia, IIa and IIIa respectively correspond to samples No.1, 2 and 3.

The mobility reduction is the P polymer /A P water ratio, where A P polymer is the pressure drop for the polysaccharide solution and A P water is the pressure drop for the saline aqueous phase without polysaccharide.

EXAMPLE 2

Example 1 has been repeated with solutions identical to solutions No.1 and 2, except that the salt concentration, expressed in NaCl, was 100 g/l.After the treatment, the obtained solutions (respectively Ib and Ilb) showed a viscosity of 8.5.10's Pa.s-'-.

Both solutions have been subjected to the filterability test (Figure 2). Only solution No.2, which had been subjected to the treatment according to the invention, showed non-clogging.

EXAMPLE 3

The test related to a raw Scleroglucane wort. A raw wort of Sclerotium Rolfsii fermentation, the fungus residues larger than 20 micrometers of which have been eliminated through filtration, has been diluted until a concentration of 600 ppm by weight in a salt solution with a sodium chloride concentration of 20 9/1.

The obtained solution (solution Ic) has then been ultrafiltered at 300C through contact with a cellulose acetate diaphragm with a cutoff zone of 20,000, as shown in Example 1. The residue (I1Ic) has then been heated up to 900C under atmospheric pressure for 4S hours. After cooling down to 300C, the obtained solution (IIc) has been subjected to the same filterability test as that described in Example 1. The fluidity reduction through 3 Millipore filters with an average pore diameter of 5 pm has been measured according to the filtered volume.

Figure 3 shows the tests corresponding to a non- treated solution (Ic), a solution that has only been ultrafiltered (IIIc) and a solution (IIc) that has been treated according to the invention (ultrafiltration and heating). It can be seen that the first two solutions very rapidly clog the filters and that only the solution that has been treated according to the invention shows a constant R, that is an excellent filterability.

9 -EXAMPLE 4

A Xanthomonas Campestris fermentation wart with a concentration of 15 g/1 has been heated at 1100C for 10 minutes and then cooled down to 300C. The wart (sample No.1) has then been diluted with a concentration of 550 ppm by weight into an aqueous solution of 5 g/1 NaCl. This solution had a viscosity of 9.7.10--- Pa.s3..

As for the preparation of sample No.2, the fermentation wart has been ultrafiltered after addinn an aqueous solution of 5 9/1 NaCl, under the same conditions as those described for sample No.2 in Example 1. It has then been subjected to the same heating and cooling as sample No.l. The wart has also been diluted with a concentration of 550 ppm by weight in an aqueous solution of 5 g/1 NaCl. The viscosity of this solution was 10.4.10-3 Pa.s--,-.

The two solutions that have been prepared with samples No.1 and 2 (respectively Id and lId) have been subjected to the filterability test (Figure 4). The wart which had been subjected to the treatment according to the invention allowed to prepare a non-clogging solution, which was not the case with the non-treated wart.

Claims

1. A process for treating a fermentation wort containing a polysaccharide in order to increase its filterability, comprising subjecting the wort to ultrafiltration through an ultrafiltration diaphragm the cut-off zone of which is between 10,000 and 100,000, by adding at least one volume of water to the wort and by allowing at least one volume of liquid per volume of the wort subjected to the ultraffitration to filter through, and heating the residue obtained at a temperature of at least 600C.

2. A process according to Claim 1, in which the diaphragm has a cut-off zone between 10,000 and 30,000.

3. A process according to Claim 1 or 2, in which the wort which is subjected to the ultraf iltration and the heating is a Xanthane wort.

4. A process according to Claim 3, in which the heating is carried out at 90-110 0 C for 5 to 15 minutes.

5. A process according to Claim 1 or 2, in which the wort is a Scleroglucane or a Schizophyllane wort and the heating is carried out at 601300C for 1 to 60 minutes.

6. A process according to any preceding claim in which 1 to 10 volumes of water or salted water is added and 1 to 10 volumes of liquid per volume of the wort subjected to the ultrafiltration is allowed to filter through.

7. A process according to any preceding claim, in which the wort subjected to the ultraffitration and heating is a Scleroglucane wort.

8. A process according to any preceding claim, in which the wort subjected to the ultrafiltration and heating comprises at least one alkalimetal salt with a concentration of 1 to 100 grams, expressed in NaCI, per litre.

9. A process according to any preceding claim, in which the ultrafiltration diaphragm is a cellulose acetate diaphragm.

11

10. A process according to any preceding claim, in which the wort is a raw wort comprising cell residues.

11. A process according to any preceding claim, in which salted water is added during the ultrafiltration.

12. A process according to Claim 1, substantially as hereinbefore described in any one of Examples 1 to 4.

13. A wort when treated by a process according to any one of the preceding claims.

Published 198,9 at The Patent Office, State House, 86171 Holborn, LondonWC1R 4TP. Further copies maybe obtained from The P&MntOMm. Sales Branch, St, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Oray, rent, Con. 1187