Alternating aeration strategy to reduce aeration energy demand for aerobic granular sludge and analysis of microbial community dynamics

Abstract

A novel energy-saving aeration operational strategy is proposed to effectively reduce energy consumption and improve the denitrification capacity of aerobic granular sludge (AGS). In this study, two sequencing batch reactors (SBRs) were operated to cultivate AGS, R1 with conventional continuous aeration and R2 operation with alternate aeration. The results showed that the granulation time of R2 was faster than that of R1, and the AGS with an average particle size of approximately 1.0–2.0 mm had a smooth surface and compact structure with excellent settleability. The alternating aeration strategy has no impact on granule stability and the removal of carbon, nitrogen and phosphorus. In addition, the high-throughput sequencing revealed that the structure of the microbial community changed significantly during operation. At the phylum level, the most abundant groups Proteobacteria and Firmicutes became gradually dominant, and Gammaproteobacteria, Bacteroidia, and Alphaproteobacteria were the dominant microorganisms at the class level. Furthermore, the most dominant bacterial genera Zoogloea and Thauera play a major role in promoting AGS granulation by secreting extracellular polymeric substances (EPS) and contributing to the removal of nutrients and the stability of granules. These findings will advance our understanding of the role of AGS technology in reducing aeration energy consumption and improving nitrogen removal and provide a foundation to guide the application of AGS alternate aeration operation strategies for wastewater treatment.