Methane emission during municipal wastewater treatment

► Methane emission from a municipal WWTP was quantified in total and per unit process. ► The anaerobic digestion related unit processes caused three quarters of the emission. ► Dissolved methane was sampled with a method based on salting-out of dissolved gases. ► Better handling of ventilation air from sludge facilities can decrease methane emission. ► Dissolved methane was aerobically oxidized in the activated sludge tank.