3. Results and discussion
3.1. Effect of different ratios between corncob and PM on biogas
production
It is known that the concentration of substrates affect the
anaerobic fermentation for biogas production. In order to reflect
the life value, acidification and methanogenic microbials demand
suitable carbon and nitrogen ratio for active metabolism in anaerobic
system. As a kind of lignocelluloses, corncob shares the feature
of carbon-rich that needs the addition of nitrogen-rich substrates
such as animal manure to balance the C/N (Ye et al., 2013). Then
PM was added into the digestion system. Different ratios of corncob
and PM led to different carbon to nitrogen (C/N) ratios for
anaerobic degradation, and it would increase the release of free
ammonia when nitrogen was rich. Meanwhile, as a consequence
of the toxic effect of ammonia on the anaerobic bacteria, large
amount of volatile fatty acids greatly influenced the biogas production
of anaerobic fermentation would be observed (Niu et al.,
2011). Then, different ratios of corncob and PM reflected different
characteristics of biogas production in this study. However, methanogenic
and acidogenic microorganisms in anaerobic inoculum
behaved particularly active when they contacted with the anaerobic
substrates. Then the biogas successfully obtained from the
anaerobic system.