The feasibility of single-stage biohythane production in a semi-continuous thermophilic bioreactor: Influence of operating parameters on the process kinetics and microbial community dynamics.

Biohythane production through anaerobic digestion of organic waste in a single reactor is a potentially more cost-effective process compared to the traditional two-stage scheme. In this work, the production and composition of biohythane obtained from complex organic waste in a semi-continuous thermophilic anaerobic bioreactor was studied with a gradual increase in hydraulic retention time (HRT) from 2 to 5 days and a corresponding decrease in the organic loading rate from 12.27 to 4.8 g VS/(L·d). At low HRT, a significant predominance of hydrogen content in biogas was observed. However, with an increase in HRT to 5 days, the volumetric and specific yield of methane increased. The modified Gompertz model and the first order model showed a high coefficient of determination (R2 = 0.97–1) for the calculated kinetic parameters of hydrogen and methane formation. At all values of HRT, the predominance of the hydrogen-producing genus Thermoanaerobacterium was observed in the microbial community. When HRT was increased to 5 days, representatives of methanogenic archaea of the genera Methanosarcina and Methanosaeta actively developed. The hydrogen and methane content in the final biogas mixture was approximately 37 % and 30 %, respectively. Potential research avenues for improving biohythane production in a single reactor have been considered. [ABSTRACT FROM AUTHOR]