Effect of mixed culture bacteria (MCB) addition, initial substrate concentration to inoculum (So/Xo), carbon to nitrogen (C/ N) ratio on the hydrogen production (HP) from organic fraction of municipal solid waste (OFMSW) via dry anaerobic digestion was investigated. The results showed that supplementation of OFMSW with MCB substantially improved hydrogen yield (HY) and HP. HYs were 306.2 ± 33.0, 149.8 ± 16.6, and 155.3 ± 22.9 mlH2/gCODremoved for OFMSW supplemented with MCB, OFMSW, and MCB, respectively. HP at So/Xo ratio of 9.2 gCOD/gVSS was 3.1 times higher than those obtained at So/Xo ratio of 1.7 gCOD/gVSS. The maximum HY of 338.4 ± 18.9 mlH2/gCODremoved was achieved at So/Xo ratio of 9.2 gCOD/gVSS. The HP and HY were substantially increased from 169.7 ± 17.1 to 524.2 ± 34.4 ml and from 163.1 ± 23.6 to 338.4 ± 18.9 mlH2/gCODremoved with increasing the C/N from 16 to 25, respectively. However, HP and HY
decreased at C/N ratio exceeding 26.6. The modified Gompertz equation model was highly fitted to the experimental data with correlation coefficient (R2>0.984). The 16S rRNA sequences showed the dominance of Pseudomonas fulva with similarity of 99%. Copyright © 2015 John Wiley & Sons, Ltd.