Solubilization of Organics Due to Thermal Hydrolysis Pretreatment and the Shift in Microbial Population in Anaerobic Digestion

A study was conducted to analyze the effect of solubilization due to thermal hydrolysis pretreatment on the microbial population responsible for anaerobic digestion at mesophilic temperature. Metagenomic and microbial population analysis was done on digesters receiving sludge with and without thermal hydrolysis pretreatment. The digester receiving thermal hydrolysis pretreatment was stable at lower detention times and showed a shift in microbial population with predominance of methane-producing population in comparison to conventional digesters receiving no thermal hydrolysis pretreatment. Among methanogens, Methanosarcina showed dominance in the thermal hydrolysis pretreatment digester. Digesters with no thermal hydrolysis pretreatment had a mixed culture of acid-producing bacteria and methane-producing archaea, with almost equal proportion of methane-producing Methanobacterium and Methanosarcina. Kinetic parameters showed high growth and substrate utilization rates in digester receiving thermal hydrolysis pretreatment.