Sugar beet membrane filtration process

摘要

The present invention relates to a process for producing sugar from beets, comprising the steps of:
(e) slicing sugar beets into cossettes and obtaining a sucrose-containing feed juice therefrom by diffusion, wherein the feed juice also comprises ash and invert sugars;
(f) filtering the sucrose-containing feed juice through a first ultrafiltration membrane that has a first molecular weight cutoff of at least about 2,000 daltons and a pore size no greater than about 0.1 microns, thereby producing a first ultrafiltration permeate and a first ultrafiltration retentate;
(g) filtering the first ultrafiltration permeate through a second ultrafiltration membrane that has a second molecular weight cutoff that is lower than the first molecular weight cutoff and is between about 500-5,000 daltons; thereby producing a second ultrafiltration permeate and a second ultrafiltration retentate; and
(h) filtering the second ultrafiltration permeate through a nanofiltration membrane; thereby producing a nanofiltration permeate and a nanofiltration retentate, wherein the nanofiltration retentate has a higher concentration of sucrose on a dry solids basis than the feed juice in step (c), and wherein the nanofiltration permeate comprises at least about 30% of the ash and at least about 30% by weight of the invert sugars present in the second ultrafiltration permeate.