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.