High-efficient nitrogen removal by coupling enriched autotrophic-nitrification and aerobic-denitrification consortiums at cold temperature

This study paid particular attention to total nitrogen removal at low temperature (10 °C) by excellent coupling of enriched autotrophic nitrifying and heterotrophic denitrifying consortiums at sole aerobic condition. The maximum specific nitrifying rate of the nitrifying consortium reached 8.85 mg N/(g SS h). Further test in four identical lab-scale sequencing batch reactors demonstrated its excellent performance for bioaugmentation in potential applications. On the other hand, the aerobic denitrifying consortium could achieve a specific denitrifying rate of 32.93 mg N/(g SS h) under dissolved oxygen of 1.0–1.5 mg/L at 10 °C. Coupling both kinds of consortiums was proved very successful for a perfect total nitrogen (TN) removal at COD/N of 4 and dissolved oxygen of 1.5–4.5 mg/L, which was hardly reached by any single consortium reported previously. The encouraging results from coupling aerobic consortiums implied a huge potential in practical treatment of low-strength domestic wastewater (200–300 mg/L COD) during wintertime.