Evaluating the efficiency of nitrogen removal through batch aerobic biotechnology by changing the ratio of chemical oxygen demand to nitrogen

Abstract

This study aimed to evaluate nitrogen removal efficiency in simulated wastewater utilizing aerobic biological technology in batch processes while varying the chemical oxygen demand to nitrogen (COD:N) ratio. Experimental results with a daily load of 1.14 kg COD/m³, a sludge concentration of 2500 - 3000 mg/L, a pH range of 7 - 8.5, and an aeration duration of 6 h per cycle (continuous 24-h operation) showed that compared to the original ratio COD:N of 100:5 (according to textbooks), the COD:N ratio of 100:7.5 was the most optimal for the treatment efficiency. Total nitrogen removal efficiency ranged from 81.7 to 93.9%, which was considered suitable for the operation of sequencing batch aerobuc tanks, with the 6-h aeration period ensuring stable performance. These results demonstrate that both assimilation and nitrification processes occurred effectively under these optimal conditions. At the same time, the system also exhibited very effective organic matter treatment capacity, maintaining COD removal efficiency above 88% regardless of the COD:N ratio applied during the study. This suggests that the treatment process is not only stable but also highly flexible, efficiently managing variations in organic loading in the wastewater.