Effect of ammonium, electron donor and sulphate transient feeding conditions on sulphidogenesis in sequencing batch bioreactors

This work aimed to study the effect of transient feeding conditions on sulphidogenesis in 8 sequencing batch bioreactors (SBR). SBR L1 and H1, operated under steady-state conditions were used as the control reactors, while four SBR were tested under transient feeding conditions, using moderate (L2 and L3, feast and famine: 2.5 and 0 g SO42-.L-1) and high (H2 and H3, feast and famine: 15 and 0 g SO42-.L-1) loads. The sulphate removal efficiency (RE) was ≥ 90% in SBR L2, L3 and H1. The NH4+ famine conditions resulted in a higher sulphate RE (≥ 40% H3) compared to feast conditions (≤ 20% H2). Besides, the sulphidogenic first-order kinetic constant was 4 % larger and the use of electron donor was 16.6% more efficient under NH4+ famine conditions. Sulphidogenesis is robust to transient feeding conditions, but not when applying high loading rates (SBR H2 and H3).