Determination of the effects of thermophilic and hyperthermophilic temperatures on anaerobic hydrolysis and acidogenesis of pig manure through a one-year study

Improving hydrolysis and acidogenesis through thermophilic and hyperthermophilic temperatures is critical for enhancing the anaerobic decomposition of animal manure. However, whether higher temperatures can provide more enhanced performance has not been elucidated experimentally. This study, therefore, conducted a continuous operation experiment at thermophilic and hyperthermophilic temperature to investigate the hydrolysis and acidogenesis of pig manure. The two temperature reactors entered a stable state after about 200 days and longterm microbial acclimation markedly changed their performances. The mass balance results showed comparable hydrolysis in both the thermophilic and hyperthermophilic reactors. The acidogenesis efficiency was indeed also comparable and relatively low at both temperatures. The occurrence of methanogenesis in the thermophilic reactor induced a significantly lower VFA concentration. The thermophilic reactor exhibited higher bacterial diversity; however, this difference between the two reactors apparently did not correlate with hydrolysis and acidogenesis performance.