OPTIMIZATION OF INTERMITTENT AERATION FOR NITROGEN REMOVAL FROM SWINE WASTEWATER

Intermittent aeration (IA) was investigated for nitrogen (N) removal from anaerobically pretreated swine wastewater (APTSW). The study focused on optimization of aeration to nonaeration (ANA) ratio and cycle time in IA systems to reduce aeration costs without compromising treatment efficiency. Five IA reactors were operated at various ANA schedules of 1 h:1 h (A), 1 h:3 h (B), 0.5 h:1.5 h (C), 0.5 h:2 h (D) and 1 h:4 h (E), to investigate which was best suited for NH3-N removal from APTSW. After several months of pseudo-steady state operation, the average effluent characteristics between May 6, 2003 and November 4, 2003 were used to determine N removing efficiency. Despite fluctuations in physical parameters in the reactors, greater than 86% total nitrogen (TN) and 86% NH3-N removal was achieved for all five reactors. Reactor A with the largest ANA ratio, achieved the greatest removal of NH3-N and TN (99% and 92%, respectively) while Reactor E with the lowest ANA ratio achieved 92% NH3-N and 91% TN removal. Therefore, for this wastewater, it is recommended to institute the lowest ANA ratio (0.2), with a cycle time of 1 h:4 h, to accomplish N removal.