Hythane (H2 + CH4) production from petrochemical wastewater containing mono-ethylene glycol via stepped anaerobic baffled reactor

•Mono-ethylene glycol rich effluents proved a high potential for Hythane production.•New configuration of ABR showed uniform organic load distribution along its length.•The effect of organic loading rate on Hythane production was assessed.•Maximum hydrogen and methane yield of 359 and 159 mlgCODremoved−1​ were achieved.

Hythane (H2 + CH4) production from petrochemical wastewater containing mono-ethylene glycol (MEG) via a novel stepped anaerobic baffled (SAB) reactor was investigated. The reactor was continuously operated for five months at constant hydraulic retention time (HRT) of 72 h and different organic loading rates (OLRs) of 0.33, 0.67 and 1.67 gCOD l−1 d−1. The maximum H2 yield of 359.01 ± 33.46 ml H2 gCODremoved−1 and H2 production rate of 5.12 ± 0.48 l d−1 were obtained at OLR of 1.67 gCOD l−1 d−1. Nevertheless, the maximum methane yield of 159.11 ± 14.72 ml CH4 gCODremoved−1 and methane production rate of 2.48 ± 0.22 l d−1 were recorded at OLR of 0.67 gCOD l−1 d−1. The maximum CH4 and H2 content of 52.08 and 49.84% were achieved at OLR of 0.33 and 1.67 gCOD l−1 d−1, respectively. Compartment-wise hythane profiles were assessed to optimize the production rate. Microbial community analysis was conducted and showed the dominant bacteria of Proteobacteria (44.3%), Firmicutes (28.9%), Chloroflexi (8.9%), Actinobacteria (5.7%), and Bacteroidetes (5.6%).