Ultrafiltration and Reverse Osmosis Recovery of Limonene from Citrus Processing Waste Streams

Commercial ultrafiltration (UF) and reverse osmosis (RO) membranes were used to concentrate the terpene, limonene, present in cold pressed oil centrifuge effluent and molasses evaporator condensate. UF membrane rejections were 78–97% for mixtures with initial limonene concentrations from 0.04–0.6%v/v. RO membrane rejection of limonene ranged from 87–99% for feed streams containing 0.06–0.23% limonene. Initial membrane flux rates for centrifuge effluents were in the range 10–100 kg/m²/hr. Evaporator condensate fluxes were higher, 25–400, while pure water rates ranged from 25 (RO) to 1000 kg/m²/hr (UF). Contact with limonene adversely affected membrane flux rates in decreasing order of severity: polysulfone > cellulose acetate > teflon-type.