Recovery of selected microbial metabolites from model solutions by reverseosmosis

Recovery of sodium citrate, gluconate, itaconate and lactate from aqueous s olutions was studied batchwise in a pilot plant equipped with a thin-film c omposite spiral-wound reverse osmosis (RO) membrane by varying the feed inp ut 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 intr insic membrane resistance. Such a deposit was removed totally using a conve ntional chemical-based cleaning procedure. (C) 2000 Elsevier Science B.V. A ll rights reserved.