Abstract: Feed-and-bleed operation is widely performed so far. For instance, Asahi Chemical Co. operated a feed and bleed electrodialysis plant (2,500 m3/day) for producing potable water in Ohoshima island, Tokyo [Koga and Mitsugami, 1978]. Asahi Glass Co. constructed large-scale blackish water desalination plants in Kashima Power Station (2,000 m3/day) and Kashima South Joint Power Station (12,000 m3/day), Ibaraki pref. Japan [Kawahara, 1994]. Okada et al.,  developed a four stage feed-and-bleed electrodialysis process for demineralizing whey. Tokuyama Inc. developed the technology to establish a closed system by means of electrodialytic reuse of waste water in a plating process [Matsunaga, 1986]. Rapp and Pfromm  removed chloride in a kraft pulping process with feed-and-bleed operation incorporated with monovalent-selective anion exchange membranes. Thompson et al.,  separated silphide from hydroxide in kraft white liquor with an electrodialysis system operated in both the batch and feed-and-bleed modes, producing sulphide-rich white liquor. Ryabtsev et al.,  developed a two-stage feed-and-bleed set-up for desalination of underground saline water. The first stage involves galvanostatic regime at increased current density, and the second stage profound in a potentiostatic regime resulting in desalted water. This chapter describes the computer simulation of a feed and bleed process [Tanaka, 2010].