Oxygen-limited autotrophic nitrification–denitrification (OLAND) in a rotating biological contactor treating high-salinity wastewater

A lab-scale rotating biological contactor (RBC) reactor operated under OLAND conditions was slowly adapted during 178 days to increasing salt concentrations going up to 30 g NaCl L−1. The reactor performed well during this experimental period. However, the removal capacity of the reactor was lower under high-salinity conditions. A removal efficiency of 84% was achieved at a N loading rate of 725 mg N L−1 d−1 and a salt concentration of 30 g L−1. The effect of salt shock loading and adaptation to 30 g NaCl L−1 on the specific nitritation and anammox activity of the biomass was investigated in short-term batch experiments. A salt shock loading of 30 g L−1 caused a 43% decrease in specific nitritation activity and 96% loss of specific anammox activity compared to reference biomass (not exposed to salt). The salt-adapted biomass (3–4 weeks) showed a specific nitritation activity that was 23% lower, and a specific anammox activity that was 58% lower, compared to the reference biomass. Overall, these results demonstrate that the OLAND process can have the potential to treat ammonium-rich brines after adaptation to high salinity.