This research work deals with possibilities of raw sugar juice purification
by micro-, ultra-, and nanofiltration. Conditions that enable to reach suc
h a juice purity for proceeding of crystallization without the prerequisite
of the whole complex of purification techniques, which involve liming, car
bonation, and filtration, were sought. Samples were treated with cross-how
micro- and ultrafiltration on ceramic membranes having mean pore size 20 nm
, 50 nm, and 100 nm. Increasing of juice purity and retention of almost 50
% of colour impurities by microfiltration is one of the most important resu
lts of this study. For nanofiltration tests, a special cross-flow testing c
ell with adjustable tangential speed of 0-3 m s(-1) has been designed. Seve
ral flat polymeric membranes have been tested. The aim was to find a membra
ne capable to reject the main part of the melassigenic elements as potassiu
m and sodium ions, i.e. elements that increase amount of waste product (mol
asses) during sugar crystallization.