The seasonal variation of emission of greenhouse gases from a full-scale sewage treatment plant

• Greenhouse gases (CO2, CH4, and N2O) emission from a STP was investigated.
• Emission factor and the inventory of total greenhouse gas emission were evaluated.
• The effect of water temperature on the CH4 emission was identified.
• Measures for reducing greenhouse gas from STP were suggested.

The seasonal variety of greenhouse gas (GHGs) emissions and the main emission source in a sewage treatment plant were investigated. The emission coefficient to treated wastewater was 291 gCO2 m−3. The main source of GHGs was CO2 from the consumption of electricity, nitrous oxide from the sludge incineration process, and methane from the water treatment process. They accounted for 43.4%, 41.7% and 8.3% of the total amount of GHGs emissions, respectively. The amount of methane was plotted as a function of water temperature ranging between 13.3 and 27.3 °C. An aeration tank was the main source of methane emission from all the units. Almost all the methane was emitted from the aeration tank, which accounted for 86.4% of the total gaseous methane emission. However, 18.4% of the methane was produced in sewage lines, 15.4% in the primary sedimentation tank, and 60.0% in the aeration tank.