Genomic dynamics of full-scale temperature-phased anaerobic digestion treating waste activated sludge: Focusing on temperature differentiation.

A robust microbial community is essential for the overall stability and performance of the anaerobic digestion process. In this study, two digesters of a full-scale temperature-phased anaerobic digestion plant treating waste activated sludge were sampled for one year. The acidogenesis reactor (AR) was run at 45 ± 2 °C for six months in Period I and was run at 38 ± 2 °C for six months in Period II. While the methanogenesis reactor (MR) was run at 36 ± 3 °C throughout the year. 16S rRNA amplicon sequencing and GeoChip 5.0 results showed that samples were clearly differentiated by reactors and periods. The elevated temperature in AR during Period I improved the effects of phase separation between the AR and MR. In AR, Fervidobacterium, assigned to Class Thermotogae, had a higher relative abundance of 8.9% in Period I. The abundance of genes involved with carbon degradation was significantly higher in Period I than Period II. In MR, the relative abundance of Methanosarcina increased from 19.8% in Period I to 30.6% in Period II. In addition, the influent characteristics, reactor performance, and operating parameters were determined as the key variables shaping the microbial community, contributing to a total of 76.3% and 69.5% of the variance of the AR and MR, respectively. Combined, this study enriches our understanding of genomic dynamics in full scale temperature-phased anaerobic digestion process.