GB1603170A

GB1603170A - Process for the purification of water containing grease and soil using a heavy solvent and apparatus for its implementation

Info

Publication number: GB1603170A
Application number: GB24950/78A
Authority: GB
Original assignee: Peignage Amedee
Current assignee: Peignage Amedee
Priority date: 1976-05-05
Filing date: 1978-05-31
Publication date: 1981-11-18
Also published as: FR2427305A2; FR2427305B2

Description

(54) PROCESS FOR THE PURIFICATION OF WATER CONTAINING GREASE AND SOIL USING A HEAVY SOLVENT, AND APPARATUS FOR ITS IMPLEMENTATION (71) We, PEIGNAGE AMEDEE, a French Limited Liability Company of 154 rue de Cartigny, Roubaix, Nord, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to the purification of water containing grease and soil using a heavy solvent, especially to the purification of water that has been used for washing untreated wool, and is an improvement in or modification of the invention described in British Application 10186/77 Serial No 1567854 of 10th March 1977 referred to hereinafter as the "main application". (Throughout this specification, the term "soil" is used in a broad sense to indicate insoluble solid impurities other than greasy matter.) The washing of untreated wool is an operation which requires large quantities of water and which results in serious contamination of the water. It is therefore very desirable to provide an efficient purification process which enables at least part of the water to be recycled and valuable materials, such as greasy matter, soil, fertilizing substances and detergent, to be recovered.

The main application describes and claims a process for the purification of waste water containing grease and soil, which comprises mixing the waste water with a heavy solvent (i.e. one more dense than water); separating the emulsion formed to obtain de-greased water, a small quantity of water-solvent emulsion, and solvent charged with greasy matter and soil; subjecting this solvent to a clarification to separate the soil; subjecting the clarified solvent to an azeotropic distillation in the presence of water, to form as tail product an emulsion from which the greasy matter can be recovered, and a head product from which the solvent can be regenerated.

In this purification process, the emulsion formed by mixing the waste water with a heavy solvent (more dense than the water) is separated so as to obtain de-greased water, a small quantity of water-solvent emulsion, which is usually recycled into the mixing device, and solvent, charged with greasy matter and soil which is subjected to various treatments to extract the soil and greasy matter and to regenerate the solvent.

The applicants have now discovered that better results are obtained from the point of view of speed and ease of implementation if, instead of recycling the small quantity of solvent emulsion, it is mixed with the solvent charged with greasy matter and soil, and this mixture then subjected to dehydration to obtain the anhydrous solvent which is then filtered.

Accordingly, the present invention provides a process for the purification of waste water containing grease and soil, which comprises mixing the waste water with a heavy solvent (i.e. more dense than water); separating the emulsion formed to obtain de-greased water, a small quantity of watersolvent emulsion, and solvent charged with greasy matter and soil; mixing the emulsion and solvent and dehydrating this mixture; clarifying the anhydrous solvent to separate the soil; subjecting the clarified solvent to an azeotropic distillation in the presence of water, to form as tail product an emulsion from which the greasy matter can be recovered, and a head product from which the solvent can be regenerated.

The process enables greasy matter, soil and certain dissolved salts to be separated, and may be used for all or only a part of the waste water. Completely de-greased and de-soiled water can be recovered as well as grease, the majority of the detergent that may be present in the waste water, and also all the soil; this soil can be recovered in anhydrous form after it has been degreased and not in the form of sludge, which would be difficult and costly to dry.

One method of separating the initial emulsion is by centrifuging.

In order to make the mixture of the small quantity of water-solvent emulsion and the solvent charged with greasy matter and soil, a vat may be provided permitting the combination of the products from the two outlets of the centrifuging separator used to separate the emulsion formed by mixing the waste water with the heavy solvent.

The mixture of the water-solvent emulsion and the solvent charged with greasy matter and soil is then dehydrated by any appropriate means, for example by centrifugation, distillation or evaporation to remove some or all of the water. The substantially anhydrous solvent recovered by dehydrating the mixture is then subjected to a clarification process which permits the separation of the soil. Preferably, the soil separated from the solvent in the clarification step is dried, preferably after de-greasing by mixing it with heavy solvent and passing it through a centrifuging machine. The solvent charged with greasy matter and resulting from the clarification of the dehydrated mixture and the de-greasing of the soil is then distilled azeotropically in the presence of water as indicated in the main application.

Preferably, grease is recovered from the emulsion obtained on azeotropic distillation, for example by centrifuging.

Furthermore, the solvent is preferably regenerated from the head product obtained on azeotropic distillation, for example by condensation and separation, and water and solvent are optionally recycled. Recycling of part of the soil-free solvent before distillation may also be carried out.

The process of the present invention applies especially to effluent from soaking, washing and rinsing wool.

Preferably, the de-greased water obtained according to the process of the present invention from the soaking water is evaporated to obtain suint; the condensate may be recycled. (The suint is that portion of the sheep's fleece which is soluble in cold water after the greasy material has been removed.) Before mixing with the solvent, the soaking water is preferably evaporated to adjust the concentration of greasy matter.

If required, the de-greased water obtained according to the present invention from the wool-washing water and preferably also the wool-rinsing water, is purified by a method knownper se.

Therefore, the present invention especially provides a purification process for water used for soaking, washing and rinsing wool, according to which the soaking water is subjected to preliminary evaporation which, if necessary, allows for the concentration of the greasy matter it contains to be adjusted to an appropriate degree, is de-greased in the heavy solvent and then subjected to a concentration by evaporation, the condensate collected being recycled, and the soluble salts which constitute the suint being recovered; and the washing water is de-greased in the heavy solvent, the emulsion and the solvent charged with greasy matter and soil from this de-greasing and the emulsion and the solvent from the de-greasing of the soaking water are mixed and dehydrated, the anhydrous solvent clarified, which enables the soil, from which the residual solvent is extracted, to be separated and dry soil recovered the solvent then being distilled by azeotropic means in the presence of water, which enables the solvent to be recovered, by separation from the head product, and subsequently recycled, and the greasy matter to be recovered in the form of an emulsion which is then centrifuged; and, if necessary, the degreased washing water is subjected, preferably in admixture with the woolrinsing water, to a conventional physicochemical purification.

According to a special method of implementation of this process, the suint recovered is mixed with the dried soil separated to obtain a fertilizing powder, which can be marketed as manure.

The process of the present invention may be implemented using an apparatus comprising a mixing apparatus for the solvent and the water to be treated, a centrifuging separator for separating the emulsion formed and having three outlets for, respectively, the de-greased water, the water-solvent emulsion and the solvent charged with greasy matter and soil, a means for mixing the products from two of the outlets (that is, the emulsion and the solvent), a dehydration device (for dehydrating this mixture), a clarifier for clarifying this mixture to separate the soil, and a distillation tower for azeotropic distillation of the clarified mixture to form, as tail product, an emulsion from which the greasy matter can be recovered, and a head product from which the solvent can be regenerated.

The present invention also provides apparatus for carrying out the process of the present invention, which comprises a) the following devices for treating the soaking water: a multi-action evaporator, followed by an emulsifier, a disc centrifuge, another multi-action evaporator and a storage means for the suint; b) the following devices for treating the washing water: an emulsifier, followed by a disc centrifuge; c) the following devices for treating the emulsions and solvents from treated washing and soaking water: a mixing vat followed by a dehydration device and this by a clarifier, being followed on the one hand by (a) a distillation tower followed, on the one hand, by (i) a Florentine separator and a device for storing and recycling the solvent, and, on the other hand, by (ii) a centrifuging separator and a storage means for the greasy matter; and on the other hand by (b) a stirrer and dispersing device for mixing solvent with the soil, followed by a centrifugal drier and a device for storing the soil from the centrifugal drier, the centrifugal drier being also connected to supply the distillation tower under (c); and d) if required, a device for the physicochemical purification of a mixture of rinsing water and de-greased washing water, for example a flocculator-decanter.

(The Florentine separator has an upper pipe for feeding the water-solvent mixture in, a side pipe for withdrawing the light phase, this pipe being in the upper portion of the separator, and an axial pipe for withdrawing the heavy phase.) The process according to the invention can be applied notably to the effluent of soaking, washing and rinsing wool.

The invention will now be described in further detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a flow sheet of a process according to the main application for the purification of effluent from wool-soaking, -washing and -rinsing; Figure 2 is a flow sheet of an apparatus for the implementation of the process illustrated in Figure 1; Figure 3 is a flow sheet of a process according to the present invention for the purification of effluent from wool-soaking, -washing and -rinsing; and Figure 4 is a flow sheet of an apparatus for the implementation of the process illustrated in Figure 3.

Insofar as the methods and the devices for implementing the stages or the process of the main application have not been modified within the framework of the present invention they remain valid for the present process. The apparatus shown in Figs. 1 and 2 is modified where appropriate.

Referring to Fig. 3, the soaking water is first subjected to a preliminary evaporation which enables the concentration of greasy matter it contains to be adjusted to a degree appropriate to the subsequent treatment, for example from 5 to 15 g/litre. Good results have been obtained with a concentration of greasy matter of approximately 9 to 10 g/litre. The condensate from this preliminary evaporation can be recycled.

Of course, if the concentration of greasy matter that the soaking water contains is satisfactory, the preliminary evaporation may be omitted.

The water of appropriate concentration is then subjected to de-greasing using a solvent more dense than water: for this, it is first mixed with the solvent, for example in an emulsifier, then subjected to centrifuging.

The ratio of the mixture of solvent: water is advantageously in the range of from 1 : 3 to 1 : 8 by volume and is preferably substantially 1 : 5 by volume. This mixing may take place at the ambient temperature or at a higher temperature as a function of the boiling point of the solvent and as a function of the characteristics of the greasy matter to be separated. Centrifuging may be carried out in a disc separator.

For de-greasing, it is advantageous to use halogenated solvents, especially carbon tetrachloride, perchloroethylene or trichloroethylene, more especially perchloroethylene. This process may, however, be carried out with non-halogenated solvents or with mixtures of solvents, in so far as these solvents or mixtures of solvents are more dense than water.

After centrifuging, three products are obtained: (i) de-greased water, containing no solvent light phase); ( an emulsion of water and solvent (middle phase), normally in the form of a gel, which is treated as described below; this emulsion forms in a small quantity, its volume usually being less than 5 % of the total volume; (iii) the solvent, charged with greasy matter and soil (heavy phase) that is mixed with the emulsion (ii) and subjected to dehydration and clarification as indicated below.

The de-greased water is concentrated by evaporation to obtain a concentrated solution of suint. The evaporated water may be condensed and recycled.

The washing water is subjected to degreasing. For effective de-greasing, it is advantageous for the content of greasy matter in this water to be in the range of from 5 to 15 g/litre. This content may, if required, be adjusted to the appropriate amount by preliminary centrifuging.

The washing water of appropriate concentration is subjected to de-greasing, in a manner analogous to that described above for the soaking water.

The solvent obtained (heavy phase) is mixed with the solvent from the de-greasing of the soaking water, and with the emulsions and dehydrated. After this the whole is subjected to clarification. After this, the solvent is substantially completely free of soil.

The soil may be de-greased by mixing with more heavy solvent in a stirrer and dispersing device and centrifuging; the recovered soil is cleared of residual solvent and, if necessary, broken down. Solvent recovered at this stage may be recycled into any convenient stage of the process. As has been indicated, the soil obtained may be mixed with the concentrated solution of suint to form, after drying, a marketable fertilizing product, or may be used as such, for example in the manufacture of goods made of terra cotta.

One part of the solvent may be recycled into the device for mixing the solvent and the washing water. The other part is subjected to an azeotropic distillation in the presence of water. In the case of perchloroethylene, good results were obtained by recycling 213 of the solvent and subjecting the remaining third to a distillation in the presence of 30 of water under a vacuum of approximately 30 to 40 cm Hg.

The head product is condensed and separated, for example in a Florentine separator, into water and solvent, these two products being recycled.

The tail product (emulsion of wool grease) is treated in a centrifuging separator to separate the wool grease and the water, which contains a reasonable quantity of the detergent that was originally present in the washing water. The washing water may be recycled.

If the rinsing water is not suitable for re-use or discarding, it is mixed with the de-greased washing water and purified by conventional physico-chemical means. The mixture may, for example, be treated in a flocculator-decanter in the presence of a tlocculant, preferably ferric chloride, or subjected to flotation treatment.

Referring to Fig. 4, the soaking water is collected in a tank 1, then evaporated in an evaporator 2. The water condensed may be recycled to the wool-washing apparatus. The concentrated soaking water from the evaporator 2 is then mixed with a solvent in an emulsifier 3, then centrifuged in the separator 4 to separate soil- and grease-containing solvent, a small quantity of water-solvent emulsion and de-greased water which is evaporated in an evaporator 5. The evaporated water is condensed in a condensor 6 and recycled into the wool-washing apparatus, while the concentrated suint is stored in a vat 7. The suint is taken up again, then mixed with dry soil in a mixer 8. The mixture is then dried in a drum drier 9.

The solvent separated from the separator 4 is mixed with that separated during the purification of the washing water.

The washing water is collected in a tank 10, then mixed with solvent in an emulsifier 11.

The mixture is then centrifuged in a separator 12 to separate de-greased water, a small quantity of solvent-water emulsion and solvent. The emulsions and solvents from separators 4 and 12 are mixed in vat 26, dehydrated in dehydration device 27 and clarified in a clarifier 13. One portion is recycled into the emulsifier 11, and one portion is retained, mixed with fresh water and distilled in a column 14. The azeotropic mixture is condensed in a condensor 15. The water is separated from the solvent in a Florentine separator 17, then recycled, to be mixed with the solvent to be distilled in the column 14. The solvent collected is recirculated by a pump 18 into the emulsifiers 3 and 11, fresh solvent being added from a storage tank 16 to compensate the solvent losses. The aqueous emulsion of wool grease collected at the base of the distillation column 14 is separated by a centrifuge 19.

The grease is collected, and the water containing the detergent is recycled into the washing tank.

The soil extracted from the solvent by the clarifier 13 is dried in a drier 23, or optionally after mixing with more solvent in a stirring and dispersing device 28 followed by drying in a centrifugal drier, taken up by a worm conveyor 24 and stored in a silo 25.

The rinsing water is collected in a tank 20, mixed with de-greased washing water from the separator 12, then flocculated and decanted in a flocculator-decanter 21, the flocculant being supplied by a unit 22.

The water treated in this manner can be thrown away in the receiving area.

The process of the invention has a number of advantages. With the process, it is possible: - to recover all the soil in powder form; - to recover almost all the greasy matter; - to provide in marketable form a powder containing the natural fertilizing substances constituting suint; - to recover most of the detergent used for washing the wool; - after purification, to recycle part of the waste water; and - to throw away the part that has not been recycled, without the contamination of this water having an adverse effect on the receiving area.

According to the de-contamination needs and volumes of water to be treated, it may be necessary to implement only one part of the purification process described above. Thus, for example, it is possible to carry out the treatment of the washing water only.

WHAT WE CLAIM IS: 1. A process for the purification of waste water containing grease and soil (as hereinbefore defined), which comprises mixing the waste water with a solvent more dense than water; separating the emulsion formed to obtain de-greased water, a small quantity of water-solvent emulsion, and solvent charged with greasy matter and soil; mixing the emulsion and solvent and dehydrating this

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cleared of residual solvent and, if necessary, broken down. Solvent recovered at this stage may be recycled into any convenient stage of the process. As has been indicated, the soil obtained may be mixed with the concentrated solution of suint to form, after drying, a marketable fertilizing product, or may be used as such, for example in the manufacture of goods made of terra cotta. One part of the solvent may be recycled into the device for mixing the solvent and the washing water. The other part is subjected to an azeotropic distillation in the presence of water. In the case of perchloroethylene, good results were obtained by recycling 213 of the solvent and subjecting the remaining third to a distillation in the presence of 30 of water under a vacuum of approximately 30 to 40 cm Hg. The head product is condensed and separated, for example in a Florentine separator, into water and solvent, these two products being recycled. The tail product (emulsion of wool grease) is treated in a centrifuging separator to separate the wool grease and the water, which contains a reasonable quantity of the detergent that was originally present in the washing water. The washing water may be recycled. If the rinsing water is not suitable for re-use or discarding, it is mixed with the de-greased washing water and purified by conventional physico-chemical means. The mixture may, for example, be treated in a flocculator-decanter in the presence of a tlocculant, preferably ferric chloride, or subjected to flotation treatment. Referring to Fig. 4, the soaking water is collected in a tank 1, then evaporated in an evaporator 2. The water condensed may be recycled to the wool-washing apparatus. The concentrated soaking water from the evaporator 2 is then mixed with a solvent in an emulsifier 3, then centrifuged in the separator 4 to separate soil- and grease-containing solvent, a small quantity of water-solvent emulsion and de-greased water which is evaporated in an evaporator 5. The evaporated water is condensed in a condensor 6 and recycled into the wool-washing apparatus, while the concentrated suint is stored in a vat 7. The suint is taken up again, then mixed with dry soil in a mixer 8. The mixture is then dried in a drum drier 9. The solvent separated from the separator 4 is mixed with that separated during the purification of the washing water. The washing water is collected in a tank 10, then mixed with solvent in an emulsifier 11. The mixture is then centrifuged in a separator 12 to separate de-greased water, a small quantity of solvent-water emulsion and solvent. The emulsions and solvents from separators 4 and 12 are mixed in vat 26, dehydrated in dehydration device 27 and clarified in a clarifier 13. One portion is recycled into the emulsifier 11, and one portion is retained, mixed with fresh water and distilled in a column 14. The azeotropic mixture is condensed in a condensor 15. The water is separated from the solvent in a Florentine separator 17, then recycled, to be mixed with the solvent to be distilled in the column 14. The solvent collected is recirculated by a pump 18 into the emulsifiers 3 and 11, fresh solvent being added from a storage tank 16 to compensate the solvent losses. The aqueous emulsion of wool grease collected at the base of the distillation column 14 is separated by a centrifuge 19. The grease is collected, and the water containing the detergent is recycled into the washing tank. The soil extracted from the solvent by the clarifier 13 is dried in a drier 23, or optionally after mixing with more solvent in a stirring and dispersing device 28 followed by drying in a centrifugal drier, taken up by a worm conveyor 24 and stored in a silo 25. The rinsing water is collected in a tank 20, mixed with de-greased washing water from the separator 12, then flocculated and decanted in a flocculator-decanter 21, the flocculant being supplied by a unit 22. The water treated in this manner can be thrown away in the receiving area. The process of the invention has a number of advantages. With the process, it is possible: - to recover all the soil in powder form; - to recover almost all the greasy matter; - to provide in marketable form a powder containing the natural fertilizing substances constituting suint; - to recover most of the detergent used for washing the wool; - after purification, to recycle part of the waste water; and - to throw away the part that has not been recycled, without the contamination of this water having an adverse effect on the receiving area. According to the de-contamination needs and volumes of water to be treated, it may be necessary to implement only one part of the purification process described above. Thus, for example, it is possible to carry out the treatment of the washing water only. WHAT WE CLAIM IS:

1. A process for the purification of waste water containing grease and soil (as hereinbefore defined), which comprises mixing the waste water with a solvent more dense than water; separating the emulsion formed to obtain de-greased water, a small quantity of water-solvent emulsion, and solvent charged with greasy matter and soil; mixing the emulsion and solvent and dehydrating this

mixture; clarifying the anhydrous solvent to separate the soil; subjecting the clarified solvent to an azeotropic distillation in the presence of water, to form as tail product an emulsion from which the greasy matter can be recovered, and a head product from which the solvent can be regenerated.

2. A process as claimed in claim 1, wherein the dehydration step is carried out by centrifugation.

3. A process as claimed in claim 1, wherein the dehydration step is carried out by distillation.

4. A process as claimed in any one of claims 1 to 3, wherein the soil separated in the clarification step is de-greased by mixing with a heavy solvent and separating this solvent charged with greasy matter.

5. A process as claimed in claim 4, wherein the separation of the added solvent from the soil is carried out by centrifugation.

6. A process as claimed in claim 4 or claim 5, wherein the solvent separated from the soil is mixed with the anhydrous solvent obtained in the clarification step before azeotropic distillation.

7. A process as claimed in any one of claims 1 to 6, wherein dry soil is recovered by removal of residual solvent.

8. A process as claimed in any one of claims 1 to 7, wherein the solvent is separated from the head product obtained on azeotropic distillation and is re-used for the treatment of the waste water.

9. A process as claimed in any one of claims 1 to 8, wherein grease and, optionally, detergent, is recovered by centrifuging the tail product obtained on azeotropic distillation.

10. A process as claimed in any one of claims 1 to 9, which comprises the treatment of the effluent from wool-soaking and/or the treatment of the effluent from wool-washing.

11. A process as claimed in claim 10, wherein the de-greased water obtained from the treatment of wool-soaking water is evaporated to recover the suint.

12. A process as claimed in any one of claims 1 to 8, for the treatment of effluent from wool-soaking and -washing wherein the soaking water is de-greased in a solvent more dense than water and the de-greased water obtained is evaporated to recover suint, the washing water is de-greased in a solvent more dense than water, and the emulsion and the solvent from this degreasing and the emulsion and the solvent from the de-greasing of the soaking water are mixed and dehydrated, the anhydrous solvent clarified, soil is separated and dry soil recovered, the solvent is distilled in the presence of water to recover, on the one hand, the pure solvent by separation of the head product and, on the other, the greasy matter by centrifuging the tail product.

13. A process as claimed in claim 11 or claim 12, wherein the suint is mixed with the separated soil.

14. A process as claimed in any one of claims 11 to 13, wherein the de-greased water evaporated to obtain the suint is condensed and re-used for the treatment of the wool.

15. A process as claimed in any one of claims 10 to 14, wherein the degreased water obtained from the treatment of woolwashing water is mixed with wool-rinsing water and purified by physico-chemical means.

16. A process as claimed in claim 15, wherein the physico-chemical purification is a flocculation-decantation process.

17. A process as claimed in claim 16, wherein the flocculant is ferric chloride.

18. A process as claimed in any one of claims 10 to 17, wherein the wool-soaking water is evaporated before mixing with the solvent to adjust the grease content.

19. A process as claimed in claim 18, wherein the water evaporated to adjust the grease content is condensed and re-used to treat the wool.

20. A process as claimed in any one of claims 1 to 19, wherei the grease content is adjusted to a value in the range of from 5 to 15 g/litre before treatment with the solvent.

21. A process as claimed in claim 20, wherein the grease content is adjusted to from 9 to 10 g/litre.

22. A process as claimed in any one of claims lto 21, wherein the solvent comprises a halogenated solvent.

23. A process as claimed in claim 22, wherein the solvent comprises perchloroethylene.

24. A process as claimed in any one of claims 1 to 23, wherein the ratio by volume of solvent : water to be treated is from 1 : 3 to 1: 8.

25. A process as claimed in claim 24, wherein the volume ratio is substantially 1: 5.

26. A process as claimed in any one of claims 1 to 25, wherein part of the clarified solvent before azeotropic distillation is recycled by mixing with the waste water to be treated.

27. A process as claimed in claim 26, wherein the solvent is perchloroethylene and two thirds of it is recycled, the remaining third being distilled in the presence of 30 % of water under a vacuum of from 30 to 40 cm Hg.

28. A process as claimed in any one of claims 8 to 27, wherein water is separated from the head product obtained on azeotropic distillation and is recycled into the azeotropic distillation step.

29. A process as claimed in claim 1, carried out substantially as described herein with reference to, and as illustrated by, Figs 3 and 4 of the accompanying drawings.

30. Grease which has been recovered from greasy waste water by a process as claimed in any one of claims 1 to 29.

31. Soil which has been recovered from soiled waste water by a process as claimed in any one of claims 1 to 29.

32. Suint which has been recovered from effluent from the treatment of wool by a process as claimed in any one of claims 1 to 29.

33. A mixture of suint and soil which have been recovered from the effluent from the treatment of wool by a process as claimed in any one of claims 1 to 29.

34. De-greased, de-soiled water which has been recovered from greasy and soiled waste water by a process as claimed in any one of claims 1 to29.

35. Detergent which has been recovered from waste water from a washing treatment by a process as claimed in any one of claims 1 to 29.

36. Solvent which has been used in, and recovered by, a process as claimed in any one of claims 1 to 29.

37. Apparatus suitable for carrying out a process as claimed in claim 1, which comprises es a device for mixing the solvent and the water to be treated, a centrifuging separator for separating the emulsion formed and having three outlets for, respectively, the de-greased water, the water-solvent emulsion and the solvent charged with greasy matter and soil, a means for mixing emulsion and solvent, a dehydration device for dehydrating this mixture, a clarifier for clarifying this mixture to separate the soil, and a distillation tower for the azeotropic distillation in the presence of water of the clarified mixture to form as tail product an emulsion from which the greasy matter can be recovered, and a head product from which the solvent can be regenerated.

38. Apparatus as claimed in claim 37, suitable for carrying out a process as claimed in claim 12, which comprises (i) a multi-action evaporator, an emulsifier, a disc centrifuge, another multi-action evaporator and a storage means for the suint, connected in that sequence; (ii) an emulsifier, a disc centrifuge, a mixing vat, a dehydrating device, a clarifier, a distillation tower, a Florentine separator and a device for storing and recycling the solvent, connected in that sequence, the dehydration device also being connected to the disc centrifuge mentioned under (i) as well as to the mixing vat; (iii) a centrifuging separator and a storage means for the greasy matter, connected in that sequence to the distillation tower mentioned under (ii); and (iv) a stirrer and dispersing device connected to the clarifier, for mixing solvent with the soil separated from the anhydrous solvent in the clarifier, a centrifugal drier and a device for drying and storing the soil from the centrifugal drier, connected in that sequence, the centrifugal drier being also connected to supply the distillation tower mentioned under oil) .

39. Apparatus as claimed in claim 37 or claim 38, wherein the dehydration device is a centrifuge.

40. Apparatus as claimed in claim 37 or claim 38, wherein the dehydration device is a distillation tower.

41. Apparatus as claimed in any one of claims 38 to 40, which includes a device for mixing the suint with soil which has been separated from the stirring and dispersing device and dried.

42. Apparatus suitable for carrying out a process as claimed in claim 1, substantially as described herein, with reference to, and as illustrated by, Figs. 3 and 4 of the accompanying drawings.

43. A process as claimed in claim 1, which is carried out in apparatus as claimed in any one of claims 37 to 42.