Dead-End Dynamic Ultrafiltration of Juice Expressed from Electroporated Sugar Beets

Membrane dead-end ultrafiltration of sugar beet juice (obtained from pulsed electric field assisted nonthermal pressing) was studied as an alternative method to the conventional liming-carbonation purification. A dead-end filtration module, Amicon 8200, was first used to investigate the purification efficiency of ultrafiltration with various polyethersulfone membranes (10 kDa, 50 kDa, and 150 kDa). The purity of sugar beet juice was increased from 93.6 +/- 0.5 to 96.4 +/- 0.8 % with a 10-kDa membrane. In order to improve the filtration flux, which declined tremendously during dead-end filtration due to membrane fouling, a rotating disk module (RDM) was then applied, and the investigation of the dynamic filtration behavior and filtrate quality of sugar beet juice was carried out. Compared with Amicon stirred module, the RDM had a much higher permeate flux and filtrate purity. The effect of rotating speed and molecular weight cutoff (MWCO) of membranes were studied. The permeate flux increased with rotating speed and pore size of membrane. The permeate flux increased significantly when the rotating speed was raised from 500 to 1,000 rpm, while it slightly increased at higher rotating speed (2,000 rpm). The purification efficiency of dynamic RDM filtration was about twice than that of filtration performed with Amicon stirring module.