The Source of Inoculum and the Method of Methanogenesis Inhibition Can Affect Biological Hydrogen Production from Crude Glycerol

Abstract

Crude glycerol has become an attractive feedstock for biohydrogen production via dark fermentation. However, it is necessary to determine the inoculation conditions that provide the highest biohydrogen yield. The aim of this work was to evaluate in batch assays the effect of the inoculum and methanogenesis inhibition method on biohydrogen production from crude glycerol. Four inocula were tested: anaerobic sludge treating municipal wastewater, anaerobic sludge treating brewery wastewater, goat ruminal liquid, and a mixture of the first three inocula. Each inoculum was subjected to three different treatments to inhibit methanogenesis: addition of chloroform, acid shock, and heat shock. Denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) products was used to assess microbial communities present in the pretreated inocula. The results indicate that the ruminal liquid treated with chloroform produced the highest biohydrogen yield (0.208 mol H2 mol−1 glycerol). The microbial community present after all treatments tested preserved good functionality and stability in terms of species composition, and could endure changing environmental conditions.