Hydrogen consumption capacity assessment and its inhibition in the dry anaerobic digestion process from food waste

Abstract

Hydrogen generation from food waste by dry anaerobic digestion was investigated, where different TS (total solid) contents (20%, 22%, 24%, 27%, and 30%) of the reaction system were compared, and the optimal TS was found to be 22%. The cumulative hydrogen yield began to decrease after 1.5 days, indicating a hydrogen consumption phenomenon in the reaction system. Such consumption can affect the hydrogen generation efficiency of the system. Therefore, to know the hydrogen consumption occurrence time and then take appropriate measures were important. The sludge from different reaction times of 2d, 4d, and 6d (G2, G4, and G6) was selected to evaluate the hydrogen consumption capacity. It was shown that the reaction system had a strong hydrogen consumption in all reaction bottles of G4, and the hydrogen consumption was the most intense when TS was 22%, which decreased from the peak value of 31.82 mmol/l to 29.47 mmol/L. Hydrogen production and consumption were not significant in G6; the only small change of hydrogen was observed (29.19–31.17 mmol/l). When TS was 22% and 30%, the quantity of homoacetogenic bacteria was the maximum of 3.08 × 109 copies/g and 2.39 × 109 copies/g on the 2nd day, respectively. As the most seriously hydrogen consumption group, G4 was chosen for the hydrogen consumption inhibition experiment by adding chloroform of 0.05%. It was indicated that the addition of chloroform could effectively suppress the hydrogen consumption when TS content of the reaction system was lower than 22%. This study can provide some useful information on the research of hydrogen consumption phenomenon and its inhibition.