Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
1998-06-05
2001-02-13
Cintins, Ivars (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S679000, C210S683000, C210S688000
Reexamination Certificate
active
06187205
ABSTRACT:
The present invention concerns the purification of used (or seasoned) photographic processing solutions, with a view to the recycling of these solutions or discharging them to the drains.
A photographic processing generally comprises a final step which is a passage through a washing and/or stabilization bath. The accumulation, in the washing and/or stabilization baths, of substances coming from the prior processing steps is particularly prejudicial not only to the stability of the photographic images developed to the correct maintenance of the sensitometric characteristics, but also to the possibility of recycling these washing and stabilisation baths or discharging them to the drains. After some time of use, the washing and stabilisation baths contain inorganic compounds, such as iron, silver, thiosulfate, sulfate and sulfite ions or organic compounds which are either substances used for development, fixing, or bleach fixing, or products coming from the development, or from the various processing steps. All these products contribute to raising the COD of the solution.
The problem represented by the high COD of the used photographic processing solutions is particularly critical in the case of “minilab” processing. Various techniques have been recommended for resolving this problem with a view either to recycling the solutions with the possible addition of fresh solution, without any harm to the photographic processing, or discharging to the drains without harm to the environment.
It has been for example proposed to subject the effluent to electrolytic oxidation, dialysis, reverse osmosis as described in German patent application 3 246 897, flocculation, oxidation with ozone or oxygenated water, optionally coupled with UV treatment, as described in U.S. Pat. 5,439,599 of Géhin et al. It has been also proposed to combine non-catalytic oxidation with catalytic oxidation and biological treatment, as described in European patent application 690 025.
The treatments described in the literature usually recommend the combination of two or more techniques in order to obtain satisfactory decontamination of the effluent, enabling it to be discharged, or to eliminate contaminants which would be detrimental to re-use of the effluent. Some of these techniques have a high application cost.
The object of the present invention is a method for decontaminating a photographic effluent, which is seasoned (used) photographic processing solution having a high COD, in a simple and economical fashion.
SUMMARY OF THE INVENTION
The method of the invention comprises the step of bringing the photographic effluent into contact with a fibrous polymeric alumino-silicate having an Al:Si molar ratio of between 1 and 3 under conditions and for a period such that a reduction in the iron, silver and thiosulphate content of this effluent is achieved.
REFERENCES:
patent: 3988259 (1976-10-01), Ray
patent: 4663439 (1987-05-01), Gradeff et al.
patent: 4741833 (1988-05-01), Sheikh
patent: 5534148 (1996-07-01), Suzuki et al.
patent: 5683826 (1997-11-01), Poncelet et al.
patent: 0 186 169 (1986-07-01), None
patent: 0 691 308 (1996-10-01), None
Martin Didier J.
Poncelet Oliver J.
Rigola Jeannine
Cintins Ivars
Eastman Kodak Company
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