To separate halide ions selectively from the other sub-stances in a fixing and/or bleach fixing solution without lowering the concentration of thiosulfate ions by diluting the fixing and/or bleach fixing solution by water of specified times the volume of the solution to be treated before passing through a membrane.
The used fixing solution overflowing from the processing apparatus passes through an electrolyzing apparatus and then, transferred to a tank 1, and the fixing and/or bleach fixing solution is diluted by water of a volume 0.1-10 times that of the solution to be treated before passing through the first membrane 2. The dilution of the solution is executed by using water obtained from the rinse process of photographic processing operation and pretreated by passing it through a nanofiltration membrane in a concentration mode and in a high flow rate. The solution is delivered by a pump 6 to the first nanofiltration membrane 2 and a filtration residue is fed back to the tank 1 containing the fixing solution, and the filtrate having passed through the membrane 2 is delivered to the second nano filtration membrane 3.
GUIZARD CHRISTIAN GILBERT
DIAZ JEAN FRANCOIS
