Assessment of must concentration by nanofiltration
Advancing the chemical engineering fundamentals
Filtration (T2-11P)
Keywords: nanofiltration, grape must, organic acids
The enrichment of must prior to fermentation plays an important role in the wine production industry. The enrichment is performed by adding sugar-containing products, sucrose or grape musts (concentrated must and rectified concentrated must).
This work addresses the investigation at lab scale of grape must concentration using nanofiltration (NF). Six NF membranes were tested which had molecular weight cut-offs (MWCO) between 100 to 1000 Da. To have control over the operating conditions, the feed solution is a solution of grape must that was prepared through the addition of malic acid and tartaric acid to diluted rectified grape must. The concentration of sugars varied from 150 to 200 g l-1 with the ratio of total sugars to organic acid being kept constant. NF experiments were carried out in flat-sheet cells of 13.2×10-4 m2 membrane surface area in total recirculation mode, transmembrane pressure varied from 35 to 37 bar, recirculation flow rate was set to 130 l h-1 and the feed temperature was kept at 25ºC.
NF permeation fluxes and rejection coefficients to sugar and organic acids are presented for the wide range of MWCO and of operating conditions; transmembrane pressure and feed composition.
The permeation fluxes of the membranes varied from 23 to 113 kg h-1 m-2 for the lower sugar concentration feed and from 8 to 80 kg h-1 m-2 for the higher. The rejection coefficients of sugar were higher than the ones from acids and they varied from 20% to 99% for membranes with MWCO lower than 1000 Da.
Presented Tuesday 18, 13:30 to 15:00, in session Filtration (T2-11P).
