The concentration of methane in the biogas leaving an anaerobic digester (part of a wastewater treatment system) is 55% (volume basis) at 50 °C. The remaining 45% is CO2. Calculate the concentration of methane in this biogas for the following conditions: a. In ppmV at 50 °C b. In ppmV at 15 °C c. In ?g/m3 at 50 °C d. In ?g/m3 at 15 °C