Applications and benefits of membrane filtration for the Australian sugar industry

There have been significant developments in membrane technology in recent years, both by manufacturers and suppliers of membranes and by sugar industry groups working in collaboration with research organisations and suppliers. Polymeric, stainless steel, ceramic and carbon membranes are being developed that are more suited to sugar industry applications. Most investigations have focused on filtering clarified juice either for improvements in plant capacity, sugar quality or for the production of speciality products. Membrane filtration is also being applied to refinery streams and filtrate from rotary drum mud filters. The New Applexion Process installed at Puunene factory (Maui, Hawaii) has operated since late 1994 and is recognised as the current benchmark for filtration performance in the cane sugar industry. Results obtained overseas report the complete removal of polysaccharides including dextrans, enhanced heat and mass transfer coefficients in evaporators and pans, pan boiling time reductions of 20-30%, and colour reductions in the product sugar of up to 60%. Flux levels vary with the type of membrane medium and the source of the feed stream. Results from trials conducted in late 1998 at an Australian factory indicate that flux levels for filtered clarified juice may be up to 50% higher than has been reported for overseas trials using the same polymeric membranes. The degree of separation of suspended solids and soluble impurities is similar.