Achieving partial nitrification-denitrification and phosphorus removal through AOA post-aeration with short-term hypoxia aeration

Abstract:

In order to culture nitrite DPAOs to achieve aerobic granular sludge (AGS) short-range nitrification and endogenous denitrification and phosphorus removal, three groups of SBR with the same specifications were operate in anaerobic/aerobic/anoxic followed by short aeration (AO₁A-O₂) mode. The aeration intensity and duration of aerobic/post aerobic (O₁/O₂) varied among the reactor. By comparing the operational performance and functional microbial activity of the three reactor groups over a period of 60 days, the pollutant removal efficiency and activity of functional bacteria in each system were investigated. The results showed that R2 with short time hypoxia aeration for 10 min and the DO concentrations of O₁ and O₂ at 5 and 2.5 L/(h·L) had the best nitrogen and phosphorus removal effect, and the removal rates of COD, TP, NH+₄-N and TN reached 95.49%, 95.57%, 100% and 95.52%, respectively. The optimal environment for short-range nitrification and endogenous denitrification and phosphorus removal was created by short-term aerobic starvation and low dissolved oxygen. Approximately 60% of the phosphorus removal bacteria in R2 were DPAOs, with the highst proporton being nitrite phosphate-polyphosphate bacteria, accouting for 38.76%. The R_NA of the aerobic phase of the reactor was 74.19%, which achieved high NO-₂-N accumulation. The concentration of FNA was 1.03 μg/L, which inhibited PAOs and NOB while enriching more AOB and DPAOs.