Membrane separation technology was proposed to confront the problem of inorganic dye pollutant treatment such as an indigosol dye. A modified ultrafiltration process known as micellar-enhance ultrafiltration (MEUF), was applied to remove three kinds of indigosol dye (Pink IR, Blue O4B, and vat brown). Surfactant at concentration above CMC was added to form micelle structure and solubilize the dye molecule in the feed solution. Maximum dye rejection was achieved by the MEUF of all three kinds of indigosol dye. The rejection of indigosol pink IR, blue O4B, and brown VAT1 were 94,27%, 95,49% and 99,15%, respectively. In this research, it was found that the MEUF system leads to higher membrane flux, compared to the ultrafiltration system as shown in flux profiles. The difference was expected due to different dye molecular structure. Blocking mechanism was predicted by a mathematical model based on Hermia’s model and depicted a mechanism of complete blocking on most UF process and cake formation on MEUF process. This result confirmed that the MEUF system certainly retained the dye molecule on membrane separation process. However, a comprehensive study is required to increase the membrane flux.Membrane separation, Micellar-enhance ultrafiltration, wastewater, indigo sol dye, blocking mechanism