Ultrafiltration of Raw Indian Sugar Solution Using Polymeric and Mineral Membranes

The traditional sugar industry still faces problems from the disposal of final wastes, which generally have concentrated organic materials, because of the use of chemicals for liming, sulphitation, or phosphatation in the treatment of raw cane juice and for the removal of color. In the present work, ultrafiltration and coagulation coupled with ultrafiltration are used for clarification as well as for decolorization of raw brown sugar obtained from an Indian sugar industry. Polyethersulphone (PES) membranes (5–100 kDa MWCO) and mineral Carbosep membranes (15–50 kDa MWCO) are used for decolorization of raw brown sugar solutions. Using a feed solution of 50°Brix, about 50% reduction in color at a permeate flux of 1.4 × 10–5m3/m2·s (about 50 lmh) was obtained both for PES and mineral membranes with MWCO between 30–50 kDa. The ultrafiltration process provided a juice of higher purity and lower color; thus this process could be an economic option for the sugar industry. Extended time experiments (which are under way) need to be carried out to study the long-term behavior of such membranes for application in the sugar industry.