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%).