Orange Juice Clarification by Microfiltration: Effect of Operational Variables on Membrane Fouling

Abstract

Orange juice was clarified by cross-flow microfiltration by a PVDF/PMMA flat mem-brane synthesized in our laboratory. The effect oftransmembrane pressure (ǻp=0.4-1bar) and feedflow rate (v=0.77-1.25 m/s) on permeate flux atT=25ºC was studied. Permeate flux increases withincreasing feed velocity, while no significant increaseof permeate flux with pressure is observed (flux con-trolled by mass transfer). Resistances responsible forpermeate flux in the steady state conditions wereevaluated by applying the resistance-in-series model.Results indicate that the reversible gel layer resis-tance of the membrane was the dominant resistance(§ 70% of total membrane resistance) and it wasmainly caused by the adsorption and deposition ofsolutes on the membrane surface. The PVDF/PMMAmembrane showed high performance on both per-meate flux and clarified juice quality. The maximumpermeate flux at steady-state condition (J = 47L/m2h) was achieved at ǻp = 1 bar and v = 1.25 m/s.Total solids (TS) are completely removed from per-meate juice and the content of soluble solids, acidityand pH present in the feed and in the clarified per-meate are practically the same.