The present book deals with the experiment carried out for the dye and salt removal from the feed solution of three different concentrations i.e. 12.5 ppm, 25 ppm and 50 ppm dye concentration & 500 ppm, 750 ppm and 1000 ppm salt concentration by two different Nanofiltration membranes - flat sheet membrane and Spiral wound membrane. The reuse of process water in the dye processing industry is considerable in terms of environment, economy, and industrial management by nanofiltration membranes. However, there are a lot of parameters affecting membrane performance. The book provides an indepth knowledge about the effect of concentration of component, trans-membrane pressure have a role on permeate flux and rejection. However the composition of actual dye effluent from industries may also contain other auxiliary materials like metal ions, organics, etc. which may result in membrane plugging and flux decline and therefore may not be compatible with the results obtained from the project in which the feed consisted of solely dye and salt. Further studies may be required to do a detail analysis of change in parameter.