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 degrees 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 bring 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.