Nanofiltration at elevated temperatures - An analysis of performance and economics

Nanofiltration is nowadays established in many industries for the separation and purification of aqueous solutions. The maximum operating temperature of commercial nanofiltration membrane is often given with 50 – 60 ºC based on the three-layer structure of membranes consisting of a polyester or polypropylene support paper with a polysulphone support layer and an active layer of polyamide. Operating nanofiltration at high process temperature close the limits of the membrane can have a significant impact on the performance of the membranes. This change in performance with increasing temperature divided into: (1) changes of active layer of the membrane and (2) changes related to the feed solution such decrease in viscosity, change in fouling potential etc. The aim of this paper is to study the performance and thus the impact on the process economics when operating nanofiltration at the boundaries of the temperature range at 55°C in contrast to operating it at ambient temperature of 25°C