膜法绿色制糖技术研究进展

Research progress on green production of sugar from sugarcane by membrane technology

介绍了膜法绿色制糖技术在实验室、现场中试和示范工程方面的研究进展,对甘蔗压榨汁的澄清、脱色和浓缩提纯过程中的选膜研究进行了综述,分析比较了陶瓷膜和有机膜的优劣,重点介绍了膜浓缩液中残糖回收、膜污染机理及清洗策略,展望了膜法绿色制糖技术工业化亟需解决的问题.

The green production of sugar by membrane technology is promising because the impurity removal, clarification, decolorization and concentration of sugarcane juice can be achieved by only physical separation. This technology has the advantages of not adding harmful substances, efficient, automatic and stable process, full utilization of by-products and product diversification. In this review, the research progress on green production of sugar from sugarcane by membrane technology in lab-scale experiments, pilot-scale tests and demonstration project was introduced respectively. The studies on membrane selection for sugarcane juice clarification, decolorization and concentration/purification were summarized, and the performances of ceramic and organic membranes were compared and analyzed. It was concluded that the ultrafiltration membrane with pore size from 30 nm to 100 nm was suitable for the clarification of sugarcane juice, and a loose nanofiltration membrane could achieve both high color retention and high sucrose transmission, while a tight nanofiltration was selected for the separation of sucrose and reducing sugar/salt in order to further increase the purity of juice. The recovery of residual sucrose from the membrane retentate, membrane fouling mechanisms and cleaning strategies were underlined. Diafiltration operation could recover most of sugar in the membrane concentrates, leading to a high sucrose recovery of up to 98% in the clarification and decolorization stages. Permeate flux of the ultrafiltration was dominated by membrane fouling, while for the nanofiltration, osmotic pressure played a more important role in the flux decline. Recently, the demonstration project for green production of sugar by membrane technology was successfully constructed in Guangdong Province, China, and the continuous and stable operation of such membrane filtration system was achieved, and the first batch of white sugar refined by membrane technology in China was obtained. Beside, several issues（e.g. pretreatment optimization, on-line monitor system upgradation, membrane fouling control, highly-valued product development and marketing as well as cost accounting） that need to be addressed for the industrialization of sugarcane juice refining by membrane technology were discussed.