Abstract:
Five carbon sources, including methanol, sodium acetate, glycol, glycerol, and glucose were used to investigate the denitrification performance of different electron acceptors in sequencing batch reactors (SBRs). The results demonstrated that the removal ratios and specific denitrification rates of different carbon sources all showed upward trends with the increasing of carbon nitrogen ratios (The ratio of chemical oxygen demand (COD) to total nitrogen (TN) mass concentration). The optimal carbon nitrogen ratios of five carbon resources for NO
3−-N and NO
2−-N were 5.0, 5.0, 7.0, 7.0, 8.0 and 3.0, 3.0, 3.5, 4.0, 4.0, respectively. Under the optimal carbon nitrogen ratio, the specific denitrification rates decreased with the sequence of sodium acetate, methanol, glycol, glycerol and glucose for NO
3−-N electron acceptor, and methanol, sodium acetate, glycol, glucose and glycerol for NO
2−-N electron acceptor. After calculation, the cost for treating the same concentrations of NO
3−-N increased with the sequence of methanol, glucose, sodium acetate, glycol, and glycerol, while that of NO
2−-N increased with the sequence of methanol, glucose, glycol, sodium acetate, and glycerol. Compared to NO
3−-N, NO
2−-N saved 40%—50% carbon sources cost at the same concentration. Glucose was recommended as the external carbon source with low ammonia nitrogen loading rates, and sodium acetate was recommended with high ammonia nitrogen loading rates, while glycol could be served as the substitute for sodium acetate.