The specific hydrogen production rate (SHPR) for the
different HRTs in this study is shown in Fig. 2. It was observed
that the highest SHPR was obtained at 24 h. The average SHPR
values were 13.4 ± 0.9, 255.4 ± 33.6, 185.9 ± 53.7 and
100.8 ± 15.7 mLH2/gVSremoved/d for an HRT of 72, 24, 12 and 6 h,
respectively. The SHPR obtained in our study agree with those
obtained in other studies using organic solid waste [14]. The
higher H2 production per gram of VS removed was obtained by
applying an HRT of 12 and 24 h (105.3 ± 17.9 and 103.0 ± 11.2
mLH2/gVSremoved, respectively) because no statistically significant
differences were detected between both HRTs. For the
case of HRTs of 72 and 6 h, the values were 40.3 ± 8.9 and
35.8 ± 6.7 mLH2/gVSremoved, respectively.