Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
1999-09-28
2001-10-23
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
Reexamination Certificate
active
06306303
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for cleaning soiled materials, the wastewaters from the process being chemically, mechanically and biologically treated and then returned to the process.
The industrial cleaning of soiled materials is normally carried out in washing machines using a detergent-containing aqueous liquor. After the actual washing process, the washed material is repeatedly rinsed with water and then dried and further processed. In this process, the disposal of the wastewater accumulating, which is polluted with detergent residues and other ingredients, represents a considerable cost factor. In the washing of feather or downs or in the washing of raw hide for leather manufacture, the wastewater is polluted, for example, with large amounts of emulsified fat. In the washing of dyed cotton fabrics, for example in mechanical stone-wash washing with pumice stones or in the washing of blue jeans, the wastewater contains dissolved and/or dispersed dyes and fiber residues.
In view of stricter anti-pollution legislation, the untreated wastewater is no longer allowed to leave the process so that treatment of the wastewater is unavoidable. The high consumption of freshwater for the treatment process, especially in countries and regions with limited water resources, is also a considerable cost factor.
Accordingly, there is a need for a cleaning process for soiled materials which would involve minimal water consumption and hence could be operated less expensively than known processes and which, at the same time, would lead to reduced environmental pollution by wastewater.
SUMMARY OF THE INVENTION
The present invention therefore relates to a washing process for soiled materials in which the material to be washed is contacted with an aqueous detergent-containing liquor and then rinsed at least once with water, the wastewater from the wash and rinse cycles is collected, chemically, mechanically and biologically treated and then returned to the washing process, characterized in that the treated wastewater is used both for the rinse cycle and, after addition of the detergent, for the wash cycle.
The process according to the invention is particularly suitable for washing fat-soiled material, the wastewater being treated by
A) complete or partial treatment in a fat separator after addition of a demulsifier and then
B) mechanical prepurification by flotation and/or sedimentation before the biological treatment step.
In the context of the invention, fat-soiled material is understood to be material which contains 0.3 to 16% by weight of fat, based on the weight of the material. The term “fat” in the context of the invention encompasses natural or synthetic glycerol esters of higher fatty acids as described, for example, in Römpps Chemie Lexikon, Vol. 2, pages 1339-1342, 1990. The process according to the invention is particularly suitable for cleaning feathers or downs. Besides fat, feathers and downs contain skin particles, blood, droppings, vegetable impurities and large quantities of dust. Fat-soiled material in the sense of the present invention also occurs in the washing of leather, especially raw hides.
However, the process according to the invention is also suitable for washing dye-soiled material, i.e. in the context of the invention material which releases dyes into the wastewater during washing. In this case, the wastewater is treated by complete or partial chemical and mechanical prepurification by
a) reaction with a suitable oxidizing agent and then
b) flotation and/or sedimentation before the biological treatment step.
Materials which release dyes into the wastewater include, for example, freshly dyed cotton fabrics or other textiles where excess dye is to be removed by washing as, for example, in mechanical stone-wash washing with pumice stones or in the washing of blue jeans.
The soiled material is washed in a suitable washing machine, for example a cylinder washing machine or a washer-extractor. Washing is normally carried out at temperatures of 5° C. to 60° C. However, feathers are preferably washed with cold water at temperatures of 20° C. to 30° C. while blue jeans are normally washed at up 60° C.
REFERENCES:
patent: 3841116 (1974-10-01), Klein et al.
patent: 39 10 089 (1989-10-01), None
patent: 41 24 915 (1993-01-01), None
patent: 44 07 734 (1995-04-01), None
patent: 0 578 006 (1994-01-01), None
patent: 2 589 895 (1987-05-01), None
Rompps Chemie Lexikon, Band 2 (1990) pp. 1339-1342.
Goebel Irmhild
Guhl Walter
Wieser Hans-Josef
Barry Chester T.
Drach John E.
Henkel Kommanditgesellschaft auf Aktien
Trzaska Steven J.
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