Engineering application of an improved AAO process

Abstract An improved AAO process was designed in this study, in which the pre-anaerobic section was prepositioned and water inlet by two-points method was utilized. A regulating section was added between the anaerobic and aerobic sections, and could be switched to anaerobic or aerobic sections as needed to enhance the performance of nitrogen and phosphorus removal. On this basis, the process was applied to the Xihai Sewage Treatment Plant Project (Phase III), aiming to the treatment of domestic sewage with a scale of 8×10 4 m 3 /d. Characteristics, mechanisms and design parameters of the process were introduced and the operation results were analyzed in this study. It could be found that the removal efficiencies of COD, NH 3 -N, TP and SS were 89.36%, 96.89%, 95.99% and 96.78%, respectively. All the effluent indicators meet the first-level A standard in the “Pollutant Discharge Standard for Urban Wastewater Treatment Plant” (18918-2002).