[Filamentous Sludge Microbial Community of a SBR Reactor Based on High-throughput Sequencing]

Samples were collected from a sequencing batch reactor (SBR) to characterize the similarities and differences in microbial community composition in samples using Illumina high-throughput sequencing. The main objective of this study was to characterize changes in microbial community composition during filamentous sludge bulking and control processes. The SBR working volume was 11 L, and the reactors were operated for 399 days in total. High-throughput sequencing results indicated that rich diversity existed in the microbial communities of the seeding sludge. Generally, during sludge bulking, microbial composition decreased, and after the sludge was remediated, the diversity gradually increased. The dominant bacteria in the seeding sludge were Saprospiraceae_norank, Comamonadaceae_unclassified, and Tetrasphaera, comprising 13.37%, 10.54%, and 8.59% of the community, respectively. After culturing using sodium acetate as the sole carbon source, Thiothrix and Trichosporon increased significantly from the seeding to the bulking sludge, with ranges from 0.1% to 60.14% and from 19.60% to 94.82%, respectively. After the sludge bulking was controlled, the relative abundances of Thiothrix and Trichosporon were 0.1% and 2.32%, respectively. Therefore, we postulate that increases in filamentous Thiothrix and Trichosporon were the main cause for the sludge bulking.