In recent years, nanofiltration has increasingly gained in significance. To increase efficiency in process development, particularly for new fields of application, it has become essential to use calculation tools in con unction with the process in question. The tool NF-PROJECT for the simulation of two-stage NF processes at industrial scale has already been developed and presented. Its suitability for practical application in process simulation was examined as an additional aid for process development, the results of which will be discussed in this paper. To this end, the simulation tool was applied in the treatment of spent process water from the food industry. In this case, NF-PROJECT was conducive to the selection of suitable nanofiltration membranes and to process optimization while significantly reducing the time span of process development.