Anaerobic digestion of kitchen waste with hyperthermophilically pretreated grass for biohydrogen and biomethane production

The study investigates the semi-continuous co-digestion experiments using kitchen waste and grass after hyperthermophilic pretreatment. Grass was preliminary treated at 70 Celsius degrees and then mixed with kitchen waste for anaerobic digestion in the second step, performed under mesophilic and thermophilic conditions. Simultaneously, pretreated grass was also treated in mono-digestion experiments at the same temperatures. Each experimental run was operated at two retention times of 30 and 20 days, and the digestate were collected twice a week for chemical analyses. The biogas was monitored daily with measurement of its composition, including contents of methane and hydrogen. At the end of each experimental run, the samples of the digestate were collected for metagenomic analysis