Key factors affecting on bio-hydrogen production from co-digestion of organic fraction of municipal solid waste and kitchen wastewater

• Co-digestion of OFMSW with KWW is a promising substrate for hydrogen yield.
• SRT and dilution ratio is the key factors affecting on hydrogen production.
• Hydrogen yield is SRT and dilution ratio dependant.
• H2 production is mainly due to the conversion of COD in a particulate form.
• The ratio of CODt to biomass (C/X) is optimized for H2 production.

The effects of sludge residence time (SRT) and dilution ratio (DR) on the continuous H2 production (HP) from co-digestion of organic fraction of municipal solid waste (OFMSW) and kitchen wastewater (KWW) via mesophilic anaerobic baffled reactor (ABR) was investigated. Increasing DR from 1:2 to 1:3 significantly (P < 0.1) increased the H2 yield (HY) from 116.5 ± 76 to 142.5 ± 54 ml H2/g CODremoved d, respectively. However, at a DR of 1:4, the HY was dropped to 114.5 ± 65 ml H2/g CODremoved d. Likewise, HY increased from 83 ± 37 to 95 ± 24 ml H2/g CODremoved d, when SRT increased from 3.6 to 4.0 d. Further increase in HY of 148 ± 42 ml H2/g CODremoved d, was occurred at a SRT of 5.6 d. Moreover, hydrogen fermentation facilitated carbohydrate, lipids, protein and volatile solids removal efficiencies of 87 ± 5.8%, 74.3 ± 9.12%, 76.4 ± 11.3% and 84.8 ± 4.1%, respectively.