Novel Thermal Hydrolysis and Vacuum Fermentation Technology for Volatile Fatty Acids and Methane Recovery

Thermal hydrolysis and vacuum fermentation technology for volatile fatty acids and methane recovery were studied in the anaerobic bioreactor. Integration of vacuum in the fermentation reactor leads to the following benefits: It enhanced the mass transfer due to bubbling as the reactor operates above the boiling point during the vacuum time, together with the possibility of simultaneously concentrating the solids and evaporating the liquid. It enhanced the fermentation process performance due to removing the inhibitory substances produced during the fermentation processes. VFAs yield increase by about 40% by vacuum application compared to the conventional fermentation. It controlled the acid accumulation due to the continuous extraction of VFAs from the system. The microbial community analysis revealed that the application of vacuum fermentation significantly impacted microbial diversity and composition. This impact was evidenced by the lower ASV values for the vacuum compared to the conventional reactors and the presence of a large community of Coprothermobacteraeota and Synergistetes phyla in the vacuum systems.