The main objective of this experimental investigation was CH<sub>4</sub> recovery from biogas generated in municipal and wastewater treatment plant. The polysulfone hollow fiber membrane was prepared in order to investigate the permeation properties of CH<sub>4</sub> and CO<sub>2</sub>. Permeability of CO<sub>2</sub> in Polysulfone membrane was 11-fold higher than of CH<sub>4</sub> gas. A membrane pilot plant for upgrading biogas was constructed and operated at a municipal wastewater treatment plant. The raw biogas contained 66 ~ 68 Vol % CH<sub>4</sub>, the balance being mainly CO<sub>2</sub>. The effect of the operating pressure of feed and permeate side and feed flowrate on CH<sub>4</sub> recovery concentration and efficiency were investigated with double stage membrane pilot plant. The CH<sub>4</sub> concentration in the retentate stream was raised in these tests to 93 Vol % CH<sub>4</sub>.