Effect of NaCl on nitrate removal from ion-exchange spent brine in the membrane biofilm reactor (MBfR) Available to Purchase

The H₂-based membrane biofilm reactor was used to remove nitrate from synthetic ion-exchange brine at NaCl concentrations from ∼3 to 30 g/L. NaCl concentrations below 20 g/L did not affect the nitrate removal flux as long as potassium was available to generate osmotic tolerance for high sodium, the H₂ pressure was adequate, and membrane fouling was eliminated. Operating pHs of 7–8 and periodic citric acid washes controlled membrane fouling and enabled reactor operation for 650 days. At 30 psig H₂ and high nitrate loading rates of 15 to 80 g/m² d, nitrate removal fluxes ranged from 2.5 to ∼6 g/m² d, which are the highest fluxes observed when treating 30 g/L IX brine. However, percent removals were low, and the H₂ pressure probably limited the removal flux.