A control system for nitrification / denitrification over nitrite in SBR with simultaneous mitigation of N2O emissions

International audience; A control system for limiting N2O emissions in a SBR treating an ammonium rich effluent (~500 mgN.L-1) with nitrification / denitrification over nitrite is presented. This system is based on the use of derivatives of DO and ORP signals for on line control of aerobic and anoxic periods. During the 120 days of operation, the effect of different operating conditions on N2O emissions during nitrification has been analyzed. Experimental results have highlighted the effect on N2O emissions of: HNO2 concentration, DO concentration and the presence of COD during nitrification. The control system allows reducing the N2O emission factor (N-N2O per N removed) to less than 1%.