Recirculation of gas emissions to achieve advanced denitrification of the effluent from the anaerobic treatment of domestic wastewater.

•Partial denitrification of domestic sewage after anaerobic treatment at 18 °C.•Successful denitritation using OM, CH4 and H2S as electron donors at 2 h of HRT.•Gas recirculation let to increase the NO2− removal efficiency from 77% to 98%.•Gas recirculation caused >98% NO2− removal efficiency for 95 mg NO2−-N/L of feed.•Feasible process for simultaneous removal of NO2−, OM, CH4 and H2S.