3. Results and discussion
3.1. Selection of suitable condition for fermentation liquid
production
For fermentation liquid production in this study, attention was
paid to the hydrolysis and acidogenesis processes which are usually
taken as the first two stages of anaerobic fermentation before the
generation of large amount of biogases. Due to the acidogenesis of
the hydrolyzed organic substances, pH could quickly decreased to
about 3.0 and almost be kept in the whole fermentation process,
which was a condition unfavorable for hydrogen and methane gas
production.