Performance characteristics of simultaneous nitrification and denitrification (SND) for low carbon to nitrogen (C/N) ratio wastewater in an integrated device

Ammonia and total nitrogen (TN) removal efficiencies of SND in an integrated device and its influence factors, such as DO concentration, HRT, C/N ratio, influent pH, etc., were studied and analyzed. Dynamic model of SND in the system was established and solved. The results showed that total nitrogen was decreased to 4 mg/L from 20 mg/L (80%), ammonia to 2.5 mg/L from 15 mg/L (83%) by the SND in the integrated device at conditions of DO 1.2~1.4 mg/L, HRT 20 h (8 h in the first reaction zone), C/N ratio 5:1, influent pH 7.5. K_NO3^--N 1.55, which was well above that of traditional active sludge process (0.2~0.5 mg/L), was obtained by solving dynamic model of SND in the system. The results indicated that nitrogen in low C/N ratio wastewater could be efficiently removed by this technology. The integrated wastewater treatment technology was of operation stability and the ability to resist shock loading, and could be a basis for advanced nitrogen removal of low C/N ratio small discharge from small town.