3.2. Optimization experiments of the co-digestion
Table 5 showed the GP, methane content in biogas and MPY of
the digestion operated at different ratios of FW with straw. The
methane contents in biogas of different systems were found
generally stable, which were 50% ~ 70%. When the ratio of FW to
straw was 5:1, the highest methane content in biogas reached to
67.62% (V/V). The results also demonstrated that both of the GP and
the MPY were increasing with the increasing proportion of FW. The
GP and MPYachieved maximum when the ratio of FW to straw was
close to 5:1, where the maximum of the GP and MPY was 0.582 m3/
kg-VS and 0.380 m3/kg-VS, respectively, with C/N ratio of approximate
31. Compared with individual FW fermentation and straw
fermentation, the MPY of co-fermentation was increased by 39.5%
and 149.7%, respectively.