Generation of combustible biogas from anaerobic digestion of food waste is an interesting and developing alternative for the production of a cheap source of energy. In the present work, Torlon polyamide-imide based membrane films were studied for biogas separation. In pure Torlon polymeric membrane, the methane content increased from 62% in feed biogas to 94% methane in retentate. But, there was about 3.7% methane loss into the permeate stream. In a mixed matrix membrane of Torlon-Zif8(20%), the methane content enriched from 62% in feed biogas to 96% methane in retentate, with no loss (0%) of methane into the permeate stream. Thus, this paper describes important development in the application of membranes to purify biogas and enrich its energy/calorific value.