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

Abstract 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).