Industrialization is an inevitable part of the progress of civilization. Amid several positive aspects of industrialization, it has a major derogative effect i.e. environmental pollution. Industrial waste water is a major contributor to environmental pollution and hence it needs to be treated to remove harmful contaminants before discharging to the environment. Membrane technology has emerged as one of the most appropriate technologies to treat industrial waste water and in the arena of membranes, nanofiltration membrane is the most advanced one. These are loose RO membranes for which pore size varies between 0.5–5 nm and operating pressure ranges between 5–15 bars. For these charged porous membranes the rejection is governed by both Donnan exclusion and sieving mechanism. These membranes have wide applications in treating effluents from textile, dye, leather, food, pulp and paper and metal industries. NF technology is equally applicable to remove hardness and heavy metals from ground and contaminated water.