Unveiling the potential of composite water-swollen spiral wound membrane for design of low-cost raw biogas purification

Abstract

The present study aims to verify a novel purification method for raw biogas using water-swollen composite membranes. In two module configurations, we generated water-swollen polymer gel layers on thin-film composite membranes to separate methane from other biogas species. The primary driving force of the biogas separation is the solubility differences between major biogas species. The carbon dioxide solubility, many times higher than methane, effectively rejected methane from the water-swollen membranes and resulted in the retentate concentration of 97 vol% methane for raw biogas and 98 vol% for synthetic gas. Two membrane modules connected in parallel increased the methane recovery ratio up to 58 %. At a pressure of 3 bar the water-swollen membrane proved efficient in desulfurizing feed biogas producing an outlet stream containing a low concentration of H2S of an order of 10 ppmv.