Dürr Sorpt.X SB biogas purification systems uses water only to remove H2S, CO2, and light siloxanes from digester, wastewater treatment, landfill, or other biogas streams. Designed to capture more than 98.5% of the methane and purify it to pipeline quality natural gas, the system uses a self-regenerating desiccant dryer to dry the product gas to a dew point of -40°F.