METHOD FOR TREATING WASTE DEVELOPING SOLUTION OF NEGATIVE PHOTOSENSITIVE PLANOGRAPHIC PRINTING PLATE

摘要

PROBLEM TO BE SOLVED: To provide an improved method for treating a waste developing solution generated when a great number of negative photosensitive planographic printing plates are processed. SOLUTION: In the method for treating a waste developing solution, in the case where an alkaline aqueous solution which permeates and swells the photosensitive layer of a negative photosensitive planographic printing plate but does not substantially dissolve the layer is used when the negative photosensitive planographic printing plate is processed with an alkaline aqueous solution and development is practically carried out with water in a subsequent washing section, a flocculant is added to waste water in the washing section generated by processing a great number of such printing plates to precipitate and remove dissolved or dispersed components of the photosensitive layers and the resulting supernatant is filtered and discharged.