Effect of temperature on AOB activity of a partial nitritation SBR treating landfill leachate with extremely high nitrogen concentration

This study investigates the effects of temperature on ammonia oxidizing bacteria activity in a partial nitritation (PN) sequencing batch reactor. Stable PN was achieved in a 250 L SBR with a minimum operating volume of 111 L treating mature landfill leachate containing an ammonium concentration of around 6000 mg N-NH4+ L−1 at both 25 and 35 °C. A suitable influent to feed an anammox reactor was achieved in both cases. A kinetic model was applied to study the influence of free ammonia (FA), the free nitrous acid (FNA) inhibition, and the inorganic carbon (IC) limitation. NH4+ and NO2− concentrations were similar at 25 and 35 °C experiments (about 2500 mg N-NH4+ L−1 and 3500 mg N-NO2− L−1), FA and FNA concentrations differed due to the strong temperature dependence. FNA was the main source of inhibition at 25 °C, while at 35 °C combined FA and FNA inhibition occurred. DGGE results demonstrated that PN-SBR sludge was enriched on the same AOB phylotypes in both experiments.

► Successful partial nitritation at 25 and 35 °C treating leachate at 6 g N-NH4+ L−1.
► A kinetic model was applied to study the influence of FA and FNA inhibition on AOB.
► FNA was the main source of AOB inhibition at 25 °C.
► At 35 °C, AOB inhibition was due to the combined action of FA and FNA.
► Two AOB phylotypes were found during stable state at 25 and 35 °C.