Membrane processing of an aqueous waste stream from a catalyst manufacturing plant

Separation of rhenium from a dilute aqueous waste stream of a catalyst manufacturing plant by a thin film composite polyamide membrane using the principle of reverse osmosis is studied. In the present study, permeate flux increases linearly with applied pressure, with slight increase in percent rejection of rhenium from the wastewater. Over 96% retention of rhenium by the membrane is observed. Increase in concentration of rhenium decreases permeate flux, relatively rapid in the beginning and then gradually, whereas, percent rejection increases marginally with increase in concentration and reaches a value of over 98. An attempt has been made to analyze the separation data by a graphical method of combined film theory–Solution–Diffusion model.