Temporal Anaerobic Effect on Aerobic Granular Sludge with Intermittent Influent-Intermittent Aeration

Abstract

To initiate the domestic sewage aerobic granular sludge (AGS) process, the experiment is operated by intermittent influent-effluent aeration to reduce the concentration of nitrate and the inhibition of PAO, and realize granulation by phosphate precipitation and positive electricity particles generated during phosphorus removal. The sludge from a sewage treatment plant is inoculated into the SBR reactors R1, R2, R3, and R4, for durations of 30, 60, 90, and 120 min total anaerobic time. This was used to study the effect of anaerobic time on the aerobic granular sludge system in domestic sewage. The experiment shows that reactors R1, R2, R3, and R4 are started successfully with 56, 48, 39, and 35 days, respectively. After 105 days of the operation, the respective average particle sizes reached 750, 764, 791, and 650 μm. During the operational period, at the 43rd and 47th day, phosphorus removal performance deteriorated in R1 and R2, and it recovered after the anaerobic time was extended to 90 min. The effect of nitrogen and phosphorus removal in R3 is good; at the 63-77 day the granular sludge in R4 disintegrates, and the effect of nitrogen and phosphorus removal and DPAO enrichment is decreased. During the later stage of operation, the effluent in R1, R2, R3, and R4 reaches the IA standard of the discharge standard of pollutants for municipal wastewater treatment plant. The results show that a long anaerobic time can quickly achieve granulation, however the particles easily disintegrate during a long-term operation. Longer anaerobic time can reduce the inhibition of phosphorus accumulating organisms release phosphorus by nitrate, help enrich DPAO, and obtain a better nitrogen and phosphorus removal effect.