FR2621926A1 - PROCESS FOR TREATING A FERMENTATION MOUT CONTAINING A POLYSACCHARIDE FOR THE PURPOSE OF INCREASING FILTRABILITY AND USE OF SUCH ASSISTED OIL RECOVERY MILL - Google Patents

Abstract

Process for treating a fermentation must containing a polysaccharide with the aim of acquiring good filterability. The process consists in subjecting the wort to ultrafiltration followed by heating. Curve II showed that the filterability of the must obtained is excellent. Application to enhanced oil recovery.

Description

262 1926

  The invention relates to a method for treating a fermentation broth containing a polysaccharide in order to increase the filterability thereof. It also relates to the resulting improved must and the use of this must as a thickening agent for enhanced oil recovery.

  The musts of polysaccharides are obtained by a fermentation process.

  Well-known example: a polysaccharide-producing microorganism, for example for the production of Xanthan, belonging to the genus Xanthomonas, is cultured in a nutritive aqueous medium

  containing a carbohydrate, especially glucose.

  For the production of Xanthan, it is possible for example to use Xanthomonas Campestris. To produce scleroglucan, we can use Sclerotium Rolfsii and for Schizophyllane - the mushroom

Schizophyllum Common.

  At the end of the fermentation, a fermentation must containing about 0.5 to 4% by weight of polysaccharide next to salts, residual nutrients, cells or mushroom debris is collected.

and other insoluble compounds.

  The removal of the insoluble particles present in the raw must can be carried out by filtration. There are however aggregates of macromolecules, difficult to filter substances with a pseudo-plastic behavior that tend to clog the pores of

  underground formations during assisted recovery operations.

  The elimination of these aggregates or at least the reduction of their

harmfulness is essential.

  The number of proposals in this respect is considerable as

  reflected for example by the abundant patent literature.

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  For example, US Pat. No. 3,355,447 proposes to heat a wort of Xanthan and to filter it. US Pat. No. 4,299,825 proposes heating followed by ultrafiltration, in order to produce a clarified must and

  concentrated. EP 0049 012 proposes to carry out an ultraviolet

  filtration, with or without enzymatic treatment, in order to obtain

  a concentrated solution of Xanthan.

  The performances obtained with the processes cited leave much to be desired, and there is therefore room for a process making it possible to obtain a wort having good filterability and especially filterability.

stable over time.

  The process according to the invention for the treatment of polysaccharide musts comprises, in the order of: A) ultrafiltration carried out with a membrane whose molecular weight cut-off zone (Mw) is between 10,000 and 10,000, preferably between 10 000 and 30 000, and the fraction of must which has not passed through the membrane (retentate) is collected, B) Heating of the retentate obtained in step (A), heating carried out at least 60 C, by Example 60-130 C. Impurities that have passed through the membrane may be rejected. In the above ultrafiltration, water passes through the membrane with the impurities, and the retentate obtained may be more concentrated in useful polysaccharide than the must before treatment. However, this is not the object of the invention and it is possible, if desired, to add water, preferably salt water, so as to maintain, for example, the same polysaccharide concentration in the water. must before treatment and in the retentate. A preferred embodiment even consists in continuing the ultrafiltration by progressively adding to the must at least one volume of water or salt water, for example 1 to 10 volumes, per volume of must treated, allowing filtration to take place. at least one volume of water, for example 1 to 10 volumes, and preferably a volume substantially equal to that of the added liquid. To obtain this result, it is possible to proceed batchwise or continuously, passing through several ultrafiltration cells and / or

  recycling the solution several times in the same cell.

  The preferred conditions of implementation of the invention are described below: During ultrafiltration, the polymer concentration of the must is advantageously between 5 and 100 g / l, preferably between 15 and 30 g / l. . The choice of the membrane does not appear to be decisive and good results have been obtained, for example, with membranes of cellulose acetate, cellulose ether, polyamide, polyolefin, polystyrene, sulfonated polystyrene or the like, the invention not being limited to at

  the use of any one of them.

  The wort subjected to ultrafiltration advantageously contains 1 to 100

  9 / l, expressed as NaCl, of one or more alkali metal salts.

  The pH during the ultrafiltration is advantageously chosen between 4 and 11 and the temperature is, for example, between 10 and 50 ° C., preferably between 20 and 40 ° C. During heating, the polymer concentration can be chosen from limits indicated above from 5 to 100 g / l, preferably 15 to g / 1. The optimum heating time is a function of the desired result and the nature of the polysaccharide and is most often between 1 and 60 minutes, preferably between 5 and 15 minutes for Xanthan and 1 to 24 minutes.

  hours for Scleroglucan and Schizophyllan.

  The following comparative examples illustrate the practice of the invention.

EXAMPLE 1

  A crude fermentation must of Xanthomonas Campestris was used which was diluted to bring its concentration to 380 ppm by weight; its alkali metal concentration, expressed as NaCl, has been

  brought to 5 g / liter by addition of sodium chloride.

  Three samples of the solution obtained (viscosity at 30 ° C:

  2.10 3 Pa.s-1; concentration: 380 ppm by weight) were taken.

  Sample No. 1 was heated at 110 ° C for 10 minutes then

  cooled to 30 C and subjected to the filterability test.

  Sample No. 2 was (according to the invention) ultrafiltered at 30 ° C. by contacting a cellulose acetate membrane having a cutoff area of 20,000; 5 volumes of liquid per volume of the sample n 2 were allowed to filter, while replacing the filtered liquid with an aqueous solution at 5 g / liter of NaCl. The retentate obtained

  was subjected to the same heating and cooling as the sample n 1.

  It was then subjected to the filterability test.

  Sample No. 3 was first heated and cooled as sample No. 1 and then ultrafiltered at 30 ° C. as sample No. 2 and

  finally subjected to the filterability test.

  At the end of the above treatments, the solutions Nos. 1 and 3 both had the same viscosity of 7 × 10 3 Pa.s-1 at 30 ° C. and the solution No. 2 had a viscosity of 7.7 × 10 -3 Pa.s-1 at C. The filterability test consisted in injecting under low shear rate conditions (t = 5 s -1) and at 30 ° C. the polymer solution through three Millipore filters of average pore diameter F m and measure the reduction of mobility (R) in the filters in

function of the filtered volume (V).

  The curves Ia, IIa and IIIa respectively correspond to

samples 1, 2 and 3.

  The reduction in mobility is the ratio b P polymer / Z.P water o, P polymer is the pressure drop for the polysaccharide solution and iP water the pressure drop for the aqueous phase saline without

corresponding polysaccharide.

EXAMPLE 2

  Example 1 was repeated with solutions identical to solutions Nos. 1 and 2, except that the salt concentration, in NaCl, was

of 100 g / liter.

  After treatment, the solutions obtained (respectively Ib and

  IIb) had a viscosity of 8.5 × 10-3 Pa.s-1.

  Both solutions were subjected to the filterability test (Figure 2). Only solution 2, which had undergone the treatment of

  the invention was non-clogging.

EXAMPLE 3

  The test focused on a raw must of Scleroglucan. A crude fermenting must of Sclerotium Rolfsii was diluted to a concentration of 600 ppm by weight in a salt solution with a concentration of 20 g / l.

sodium chloride.

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  The solution obtained (solution Ic) was then ultrafiltered at C by contacting a cellulose acetate membrane with a cutoff area of 20,000, as described in Example 1. The retentate (IIIc ) was then heated at 90 ° C under atmospheric pressure for 48 hours. After cooling to 30 C, the solution obtained (IIc) underwent the same filterability test as that described in Example 1. The mobility reduction through 3 Millipore filters of pore diameter

  average 5 μm was measured as a function of the filtered volume.

  FIG. 3 shows the tests corresponding to an untreated solution (Ic), a solution only ultrafiltered (IIIc) and a solution (IIc) having undergone the treatment of the invention (ultrafiltration followed by heating). It can be seen that the first two solutions clog the filters very quickly and that only the solution treated according to the invention has a constant R

  that is, excellent filterability.

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Claims (8)

  1 - Process for the treatment of a fermentation broth containing a polysaccharide with the aim of increasing its filterability, characterized in that: a) The wort is first subjected to ultrafiltration through an ultrafiltration membrane of which the cutting zone, molecular weight, is between 10,000 and 100,000, and b) The retentate obtained in step (a) is then heated to a temperature of at least 60 ° C. 2 - Process according to claim 1 in which the membrane presents   a cutoff area of 10,000 to 30,000.   3 - Process according to claim 1 or 2 wherein the wort subjected to   ultrafiltration and heating is a must of Xanthan.   4 - Process according to revendicaction 1 or 2 in which the must submitted to   ultrafiltration and heating is a must of Scleroglucan.   - Process according to claim 1 or 2 wherein the wort subjected to   ultrafiltration and heating is a must of Schizophyllan.   6 - Process according to one of claims 1 to 5, wherein the wort   subjected to ultrafiltration and heating contains at least one alkali metal salt at a concentration of 1 to 100 grams, calculated as NaCl, per liter.   7 - Process according to claim 4 or 5 wherein the wort is a must of Scleroglucan or Schizophyllan and the heating is carried out   at 60 - 130 C for 1 to 60 minutes. 2621 9 2 6   - 8 - 8 - Process according to claim 3 wherein the wort is a must of Xanthane and heating is carried out at 90 - 110 C for 5 to 15 minutes.   9 - Process according to one of claims 1 to 8 wherein the   Ultrafiltration membrane is a cellulose acetate membrane.   - Method according to one of claims 1 to 9 wherein the must   is a raw must containing cellular debris.   11 - Method according to one of claims 1 to 10 wherein   continues ultrafiltration until at least one volume of aqueous phase has passed through the ultrafiltration membrane by adding at least   a volume of water or salt water in the must subjected to ultrafiltration.   12 - Must obtained by the process of any one of claims 1   to 11. 13 - Use of the wort of claim 12 for recovery assisted by oil.