Recovery of selected microbial metabolites from model solutions by reverse osmosis

Recovery of sodium citrate, gluconate, itaconate and lactate from aqueous solutions was studied batchwise in a pilot plant equipped with a thin-film composite spiral-wound reverse osmosis (RO) membrane by varying the feed input absolute pressure (Pi) from 31 to 61 bar at 40°C. In all cases, flux decreased linearly with molar solute concentration, thus showing that osmotic pressure is the major resistance to overcome. After a discontinuous operation of 2.5 years, the overall membrane resistance resulted in being affected by membrane fouling, that represented about one-thirds of the intrinsic membrane resistance. Such a deposit was removed totally using a conventional chemical-based cleaning procedure.