Performance and Microbial Mechanisms of Aerobic Granular Sludge for Textile Dyeing Wastewater Treatment
This study investigated the cultivation of aerobic granular sludge (AGS) in a sequencing batch reactor (SBR) for the treatment of real textile dyeing wastewater, focusing on the influence of organic loading rate (OLR) on granulation and pollutant removal. After 60 days of cultivation, dense granules of approximately 1 mm diameter were formed, with extracellular polymeric substances (EPS) content of 92.22 mg·L−1, achieving COD and color removal efficiencies of 88.5% and 73.3%, respectively. OLR significantly regulated sludge characteristics: at an OLR of 3.0 kg·(m3·d)−1, the average granule size reached a maximum of 1.38 mm, EPS content peaked at 95.21 mg·g−1, and the highest COD and color removals were observed (92.73% and 86.35%, respectively). However, an excessive OLR of 5.0 kg·(m3·d)−1 led to sludge bulking and disintegration. Microbial community analysis revealed that Proteobacteria (44.06%–49.17%) and Bacteroidetes (27.49%–29.64%) were the dominant phyla, with their abundances significantly correlated with EPS protein secretion and pollutant removal efficiency. This study elucidates the mechanism by which OLR optimizes textile wastewater treatment through modulation of microbial community structure and EPS secretion, providing a theoretical basis and technical support for the practical application of AGS in textile dyeing wastewater treatment.