GB1597473A - Process for treating an aqueous emulsion containing lanolin - Google Patents

Description

(54) PROCESS FOR TREATING AN AQUEOUS EMULSION CONTAINING LANOLIN (71) We FISONS LIMITED, a British Company, of Fison House, 9 Grosvenor Street, London WIX OAH, 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 a process for treating an aqueous emulsion containing lanolin, notably the effluent arising from the treatment of wool.

In the alkaline scouring of wool, there is produced an effluent which contains greases. Not only are these greases valuable as a source of lanolin, but also the BOD and COD of the effluent are high and thus render the effluent unsuitable for discharge to waste. It has therefore been proposed to treat the effluent to recover the greases therefrom by centrifuging the effluent to remove part of the greases therefrom and then treating the remaining liquor with acid to liberate further greases which are separated by a second centrifuging step. However, the final effluent still has high BOD and COD levels.

We have now devised an improved method for treating such effluents.

Accordingly, the present invention provides a process which comprises treating an aqueous emulsion containing lanolin with a flocculating agent at a pH value of less than 7 and separating the resultant flocs from the emulsion.

The emulsions which can be treated by the process of the invention are derived from a wide range of sources and include, for example, the scouring of wool. For simplicity the invention will hereinafter be described in terms of wool scouring effluent.

Other lanolin containing emulsions may be treated in a similar manner to that described herein.

The wool scouring effluent comprises an aqueous emulsion of greases having suspended solids therein and having an elevated pH which is typically greater than 10, e.g. about 12. This effluent may be subjected to an initial solids and/or grease separation if desired, e.g. by filter or centrifuge and then is subjected to treatment with an acid, e.g. sulphuric acid, to lower the pH to a value of less than 7, e.g. 2 to 4 and with a flocculating agent. Suitable flocculating agents for present use include aluminium salts and hydroxides, ferrous and ferric salts and hydroxides and high molecular weight synthetic flocculating agents, e.g. homo- and cpolymers of acrylamide, notably polyacrylamides and copolymers of acrylamide with substituted alkyl acrylates. If desired, mixtures of flocculating agents may be used, as when a polyacrylamide is used to precipitate flocculateable solids and ferric chloride is used to provide absorbent floc surfaces.

The flocculating agents may be used in their commercially available forms and purity.

Where salts are used, these may be in the form of hydrates thereof.

The flocculating agent may also be formed in situ in the emulsion by chemical reaction and/or by alteration of the pH.

Thus, a particularly preferred flocculating agent for present use is a solution of ferric chloride which is soluble in the effluent at high pH values but which forms flocs when the pH is reduced to below 7, e.g. 6 to 3.

The flocculating agent or precursor thereof may be added to the effluent by any suitable means, e.g. as a powder, suspension or solution. It is preferred to agitate the effluent during addition of the agent to ensure adequately uniform mixing.

The amount of flocculating agent employed will depend upon the amount of grease present, the nature of the agent and the degree of grease removal required. The optimum amount required may be readily determined in any given case. However, as a general guide, from 0.004% to 1.0% w/w of the flocculating agent (notably ferric chloride) based on the liquid phase of the effluent will usually give satisfactory results.

The mixture of effluent and flocculating agent is preferably held quiescent for a period, typically 10 to 120 minutes, to permit the flocs to develop. After this the liquid phase is separated from the flocs by any suitable method, preferably by filtration and/or decanting.

The treated effluent has a reduced BOD and COD and the greases have been readily separated therefrom. The treated effluent may be treated further, e.g. by biological degradation (preferably after treatment with a calacreous compound to precipitate any sulphates therefrom) or chlorination; or may be discharged to waste.

The invention will now be illustrated by the following Example in which all parts and percentages are given by weight unless stated otherwise.

The drawing accompanying the provisional specification is a diagrammatic flow sheet for a process for the scouring of wool.

Wool is scoured in vessel 1 at a temperature of about 55"C with a liquor containing sodium carbonate and anionic surface-active agents to remove the grease from the wool.

The effluent from vessel 1 contains suspended solids, emulsified and dissolved grease, and has a pH of 9.5. This liquor is then centrifuged in centrifuge 2 to remove the suspended solids (4.5% of the effluent) and part of the grease (7.5% by volume of the effluent). The resultant liquor amounted to 88% by volume of the initial effluent and contained 1,900 mg/l oil and dissolved grease and had a COD of 23,590 ppm. In a conventional process the pH of the effluent would have been adjusted in vessel 3 to a value of 2.0 by the addition of sulphuric acid. The acidified liquor would have been centrifuged again in centrifuge 4 to remove the liberated oils. The resultant liquor would have had a COD of 21,090 ppm.

However using the process of the invention, the effluent from centrifuge 2 was mixed in vessel 3 with ferric chloride solution (2% v/v on liquid phase as a 40% aqueous solution). The pH of the mixture was adjusted to a value of 2 with hydrochloric acid. The mixture was stirred during mixing and then passed to vessel 5 where it was held quiescent for 30 minutes to permit floc formation. The mixture was then filtered to give a filtrate containing only 190 mg/I of grease and having a COD of 2,520 ppm.

WHAT WE CLAIM IS: 1. A process which comprises treating an aqueous emulsion containing lanolin with a flocculating agent at a pH value of less than 7 and separating the resultant flocs from the emulsion.

2. A process as claimed in claim 1, wherein the emulsion is that obtained from the scouring of wool.

3. A process as claimed in either of claims 1 or 2, wherein solids and/or grease are separated from the emulsion before the emulsion is treated with the flocculating agent.

4. A to 3, process as claimed in any one of claims 1 to 3, wherein the flocculating agent is selected from aluminium salts and hydroxides, ferric and ferrous salts and hydroxides and homo- and co-polymers of acrylamide.

5. A process as claimed in any one of claims 1 to 3, wherein the flocculating agent is ferric chloride.

6. A process as claimed in any one of claims 1 to 5, wherein from 0.004 to 1% by weight of flocculating agent based on the weight of the liquid phase of the emulsion is incorporated into the emulsion.

7. A process as claimed in claim 1 substantially as hereinbefore described.

8. A process as claimed in claim 1 substantially as hereinbefore described in the Example.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. and/or decanting. The treated effluent has a reduced BOD and COD and the greases have been readily separated therefrom. The treated effluent may be treated further, e.g. by biological degradation (preferably after treatment with a calacreous compound to precipitate any sulphates therefrom) or chlorination; or may be discharged to waste. The invention will now be illustrated by the following Example in which all parts and percentages are given by weight unless stated otherwise. The drawing accompanying the provisional specification is a diagrammatic flow sheet for a process for the scouring of wool. Wool is scoured in vessel 1 at a temperature of about 55"C with a liquor containing sodium carbonate and anionic surface-active agents to remove the grease from the wool. The effluent from vessel 1 contains suspended solids, emulsified and dissolved grease, and has a pH of 9.5. This liquor is then centrifuged in centrifuge 2 to remove the suspended solids (4.5% of the effluent) and part of the grease (7.5% by volume of the effluent). The resultant liquor amounted to 88% by volume of the initial effluent and contained 1,900 mg/l oil and dissolved grease and had a COD of 23,590 ppm. In a conventional process the pH of the effluent would have been adjusted in vessel 3 to a value of 2.0 by the addition of sulphuric acid. The acidified liquor would have been centrifuged again in centrifuge 4 to remove the liberated oils. The resultant liquor would have had a COD of 21,090 ppm. However using the process of the invention, the effluent from centrifuge 2 was mixed in vessel 3 with ferric chloride solution (2% v/v on liquid phase as a 40% aqueous solution). The pH of the mixture was adjusted to a value of 2 with hydrochloric acid. The mixture was stirred during mixing and then passed to vessel 5 where it was held quiescent for 30 minutes to permit floc formation. The mixture was then filtered to give a filtrate containing only 190 mg/I of grease and having a COD of 2,520 ppm. WHAT WE CLAIM IS:

1. A process which comprises treating an aqueous emulsion containing lanolin with a flocculating agent at a pH value of less than 7 and separating the resultant flocs from the emulsion.

2. A process as claimed in claim 1, wherein the emulsion is that obtained from the scouring of wool.

3. A process as claimed in either of claims 1 or 2, wherein solids and/or grease are separated from the emulsion before the emulsion is treated with the flocculating agent.

4. A to 3, process as claimed in any one of claims 1 to 3, wherein the flocculating agent is selected from aluminium salts and hydroxides, ferric and ferrous salts and hydroxides and homo- and co-polymers of acrylamide.

5. A process as claimed in any one of claims 1 to 3, wherein the flocculating agent is ferric chloride.

6. A process as claimed in any one of claims 1 to 5, wherein from 0.004 to 1% by weight of flocculating agent based on the weight of the liquid phase of the emulsion is incorporated into the emulsion.

7. A process as claimed in claim 1 substantially as hereinbefore described.

8. A process as claimed in claim 1 substantially as hereinbefore described in the Example.