Succession from acetoclastic to hydrogenotrophic microbial community during sewage sludge anaerobic digestion for bioenergy production

Abstract

Abstract To evaluate microbial profiling during the anaerobic digestion (AD) of sewage sludge (SWS) from a municipal Wastewater Treatment Plant (WWTP), a Biochemical Methane Potential (BMP) assay operating at 37°C mono-digestion was performed. The results from 16S ribosomal RNA (rRNA) gene sequencing, utilizing the Illumina MiSeq platform, revealed a core bacterial community in the solid material, dominated by variations in the profiles. The relative abundance in the SWS (before AD) was as following: Proteobacteria > Bacteroidota > Actinobacteriota. After AD, the relative abundance shifted to Firmicutes > Synergistota > Proteobacteria. At the genus level, Sporanaerobacter and Clostridium were dominant. The methanogenic community presented a shift in metabolic pathway from acetoclastic to hydrogenotrophic in the lab-scale reactors. The dominance of methanogenic groups at the genus level was represented by Methanosaeta > Methanolinea > Methanofastidiosum. After AD, the dominance shifted to Methanobacterium > Methanosaeta > Methanospirillum. This shift in the metabolic pathway could be related to the increase in Firmicutes, especially the population of Clostridia, which contains acetate-oxidizing bacteria that convert acetate to hydrogen.