Abstract: This study investigated the application of an ultrafiltration ceramic membrane (0.04 μm) to refine defecated sugarcane juice. The sugarcane juice was ultrafiltrated for 30 h under the following conditions: transmembrane pressure difference 0.45–0.50 MPa, crossflow velocity 4.0–4.5 m/s, and temperature 75–97 ℃. The membrane permeate flux was decreased from 350.6 to 160.2 L/(m2·h) during the ultrafiltration process and the average flux rate was 177.8 L/(m2·h), which could meet the requirement of industrial production. The apparent purity of sugarcane juice was increased by 2.01 units after ultrafiltration, the percentage removal of pigments was 20.20%, and the clarity was elevated from 79.18% to 99.98%. A fouling layer comp was formed on the membrane surface during the ultrafiltration process, which mainly consisted of organic depositions (e.g., polysaccharides, proteins, aliphatics and phenols) as well as lesser amount of inorganic components such as Na, Mg, Al, Si, P, Cl, K, Ca and Fe. A flux recovery rate of higher than 95.5% was obtained with good repeatability when fouled membrane was successively rinsed with clean industrial water, a mixed solution of 1.0% NaOH and 0.5% NaClO, and 0.5% HNO3 solution, suggesting that this cleaning method was feasible.

Key words: ceramic membrane, ultrafiltration, sugar refining, defecation, clarified juice