A microbiome study on the anaerobic digestion process during parallel and serial operation mode

Anaerobic digestion is a common procedure of treating sewage sludge at wastewater treatment plants. However, plants differ in terms of the number or reactors and, in case of several reactors, their operation mode. Both parallel and serial mode comeshave their with advantages, mainly robustness and increased methane yields, respectively. Seasonal differences in quality and quantity of substrates sometimes can suggest different operation modes with quick changeovers. To confirm the flexibility of well adopted, full-scale anaerobic digestion plants, we monitored the physicochemical process conditions of two continuously stirred tank reactors over one hydraulic retention time before and after the operation mode was switched process changes from parallel to serial mode. We applied microbiome profiling using Illumina amplicon sequencing as the process of substrate turnover and conversion to methane is mainly performed by microbes, by conducting amplicon sequencing and determining physicochemical properties.