SALT AND WATER PERMEABILITY IN REVERSE-OSMOSIS MEMBRANES

The permeate flux, permeate concentration, brine flux, and brine conce ntration have been experimentally determined. A pilot-scale reverse os mosis configuration consisting of 18 tubular-type cellulose acetate me mbranes has been used for the desalination of brackish water. The tran sport parameters (i.e., mass transfer coefficients) as well as the per meability coefficients (of water and salt) in reverse osmosis membrane s, useful for the prediction of the membrane performance and membrane characterization, have been calculated by fitting the model prediction s to the experimental results. A classical model, applicable for rever se osmosis systems, has been used. The effect of the operating conditi ons (pressure, flowrate, and concentration) on the model parameters ha s also been studied. Through the incorporation of six adjustable param eters to the model, the prediction results have been found to be in go od agreement with the experimental data within the accuracy of the exp erimental determination. Finally, a study of the membrane performance on the rejection of six different ions (chloride, sodium, calcium, mag nesium, bicarbonate, and sulphate) has also been made. The permeabilit y parameter values for these ions have been determined and are reporte d. This option also yielded quite satisfactory predictions, as far as the permeate concentrations and flowrates are concerned.