Liquid purification or separation – Processes – Preventing – decreasing – or delaying precipitation,...
Reexamination Certificate
1999-10-22
2001-08-07
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Processes
Preventing, decreasing, or delaying precipitation,...
C101S450100, C210S743000, C210S744000, C210S749000, C210S919000
Reexamination Certificate
active
06270677
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to processes for treating alkaline effluent solutions obtained from lithographic printing plate processing, systems for controlling such processes, and methods of controlling such processes. More particularly, this invention relates to processes for treating such alkaline effluent solutions by neutralizing the alkaline effluent solution in such a manner as to obtain a discharge solution which is readily handled and may be disposed of in an environmentally acceptable manner without further processing, systems for controlling such processes, and methods of controlling such processes.
Certain industrial processes generate effluent solutions and process streams which may be highly acidic or alkaline, depending upon the particular industrial process involved. For example, the processing of lithographic printing plates involves the use of at least one developer solution which is basic (i.e. having a pH above 7.0) and at least one finishing solution, gum solution, pre-bake solution or combinations thereof which are acidic (i.e. having a pH below 7.0). Consequently, such processing typically causes the generation of highly acidic and alkaline effluent solutions or process streams that must be further processed or treated before discharge into the environment, or they must be treated as hazardous waste, which adds additional cost and complexity to the overall process.
More particularly, the lithographic printing process typically employs the use of a highly alkaline developer solution having a pH greater than about 12.5 (for example, MX-1710, SILVERSTAR, and GOLDSTAR developers, having pH values of 13.0-13.5, as manufactured by Kodak Polychrome Graphics of Norwalk, Conn.), and highly acidic finishing, gum and pre-bake solutions having a pH less than about 5.0 (for example, MX 1612-1 and POLYMATIC finishers, having pH values of below 2.0, as manufactured by Kodak Polychrome Graphics of Norwalk, Conn.). The highly alkaline developer solutions are required, for example, to completely solubilize non-image portions of the exposed plates. The highly acidic solutions are required, for example, to completely convert the processed non-image portions of baked plates to uniformly hydrophilic surfaces. These solutions generate effluent or process streams which are classified as hazardous materials under the federal Resource Conservation and Recovery Act (RCRA) and applicable regulations. Thus, the discharge of these highly alkaline and acidic effluent streams into the environment is ordinarily impermissible without further treatment. Alternatives such as dilution of the effluent streams with water is often impermissible, and in any event is ordinarily costly and requires large quantities of fresh water, which is often not available. In addition, it has been found that simply neutralizing the highly alkaline effluent stream with the highly acidic effluent stream or with a separate acidic solution often causes the formation of unacceptable gels, sludge or precipitates.
Accordingly, it would be desirable to neutralize the alkaline effluent solution in such a manner as to avoid the formation of unacceptable gels, sludge, or precipitates. It is one object of this invention to provide a process for achieving such neutralization. It is one feature of this invention that the alkaline effluent stream is neutralized using at least one acidic solution to obtain a neutralized effluent stream, and that an additional aqueous solution or stream is used in the neutralization process to advantageously avoid the formation of unacceptable gels, sludge, or precipitates, thereby obtaining a neutralized discharge stream which may be discharged to the environment. It is another object of this invention to provide a control system for such a neutralization process. It is yet another object of this invention to provide a method of controlling such a process.
SUMMARY OF THE INVENTION
The invention is directed to a process for treating alkaline solutions obtained from lithographic printing plate processing comprising admixing at least one alkaline solution and at least one acidic solution in the presence of at least one aqueous solution to obtain a discharge solution having apH in the range of about 5 to 11.5, preferably about 7.5 to 10.5. The invention is also directed to a process for treating alkaline solutions obtained from lithographic printing plate processing comprising admixing at least one alkaline solution and at least one aqueous waste water solution to obtain an aqueous alkaline solution, and admixing the resultant aqueous alkaline solution with at least one acidic solution to obtain a discharge solution having a pH in the range of about 5 to 11.5, preferably about 7.5 to 10.5. The invention is also directed to control systems for such processes, and methods of controlling such processes.
The alkaline solution has a pH greater than 7.0, preferably greater than about 12.5, and the acidic solution has a pH less than 7.0, preferably less than about 5.0, and most preferably less than about 2.5. The alkaline, acidic and aqueous solutions are admixed in volume ratios in the range of about 1 part alkaline: 0.2-4.0 parts acidic:≧50 parts aqueous, preferably about 1 part alkaline: 0.2‥2.5 parts acidic:≧50 parts aqueous, respectively. In a particularly preferred embodiment, the volume ratios are about 1 part alkaline: 0.2-2.5 parts acid: 50-500 parts aqueous, and more preferably about 1 part alkaline: 0.2-2.5 parts acid: 50-250 parts aqueous.
The processes, systems and control methods may be used in the treatment of alkaline developer solution effluent streams and acidic effluent streams derived from finishing solution, gum solution, pre-bake solution or combinations thereof which are derived from the lithographic printing process.
REFERENCES:
patent: 4961859 (1990-10-01), Vehara et al.
patent: 5143639 (1992-09-01), Krawack
patent: 5298170 (1994-03-01), Woog
patent: 5338351 (1994-08-01), Pennaz
patent: 5411596 (1995-05-01), Pennaz
patent: 5454956 (1995-10-01), Pennaz
patent: 5602089 (1997-02-01), Pennaz
Kodak Enviromental Services Publication No. AE-122 dated Jun., 1997-3 pages.
Ginther Dean
Gopal Pradip Goolab
Horton Randolph Alben
Baker & Botts L.L.P.
Hruskoci Peter A.
Kodak Polychrome Graphics LLC
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