JP2877265B

PURPOSE:To decrease the N-S compd. in a dilute liquid and to allow a waste water treatment without lowering the desulfurization performance of desulfurizing equipment by additionally installing a decomposing device or hydrolyzing device which decomposes the N-S compd. contained in the dilute liquid to a circulating line for the dilute liquid of an electrodialyzer which produces the makeup for the desulfurizing equipment. CONSTITUTION:The waste water from the desulfurizing equipment is stored in a storage tank 1 and is then sent to a sand filter device 2. The waste water from the sand filter device 2 is then supplied to the electrodialyzer 3. The dialysis membrane used for the electrodialysis is formed by using an org. high- polymer copolymer as its base material and cation and anion exchange membranes respectively of a sulfonic acid base and amine base as its active groups. The primary concd. waste water from the electrodialyzer 3 is sent via line (f) to an evaporator 4 and the dilute liquid is partly introduced via a line (t) into the decomposing device 11 for the N-S compd. where the N-S compd. is decomposed by using sodium hypochlorite. The dilute liquid cracking the N-S compd. is again returned via a line W to a line (g).