Nitrogen removal performance of marine anammox bacteria treating nitrogen-rich saline wastewater under different inorganic carbon doses: High inorganic carbon tolerance and carbonate crystal formation

Abstract

With different inorganic carbon (IC) doses, nitrogen removal performance of marine anammox bacteria (MAB) treating nitrogen-rich saline wastewater was investigated in a sequencing batch reactor. Ammonium removal efficiency (ARE) was above 99% at 108–3600 mg/L IC, which indicated MAB had a good tolerance to high IC dose. When IC was 108–1200 mg/L, ARE reached 90% within 2.5 h. MAB activity was greatly promoted by providing adequate IC. Besides, the maximal substrate conversion rate (3.4 kg/(m3 d)) was achieved at 180 mg/L IC. Both the modified Logistic and Boltzmann models were appropriate to describe nitrogen removal at low IC doses, while the modified Gompertz model was more accurate at high IC doses. Calcium carbonate crystal was formed on the surface of MAB granule at high IC doses, which resulted in a significant deterioration of nitrogen removal performance.