SO2 and NOx emissions from sludge combustion in a CO2/O2 atmosphere

► SO2 and NOx emissions during sludge combustion were investigated under a CO2/O2 atmosphere. ► From 550 to 950 °C, the average NOx concentration firstly increased and then declined. ► As the oxygen concentration increased, the average SO2 and NOx concentration increased. ► Sludge combustion under a CO2/O2 atmosphere could simultaneously reduce SO2 and NOx emissions.