Effect of Hydraulic Retention Time on Hydrogen Production from the Dark Fermentation of Petrochemical Effluents Contaminated with Ethylene Glycol

AbstractIn this work, the performance of an Anaerobic Baffled Reactor system (ABR) was investigated for biohydrogen production from petrochemical industries’ effluents, which are contaminated with Ethylene Glycol (EG). Five different Hydraulic Retention Times (HRTs) were operated, at constant EG concentration of 1000 mgCOD/L, in order to study their effects on both hydrogen production and EG removal efficiency. Decreasing HRT gradually from 72 to 18hrs affected the hydrogen yield to be increased from 45.50 to 377.03ml HR2R/gCODRremoved especially, when the HRT was decreased to 36 and 18hrs. The results for Volatile Fatty Acids (VFAs) compositions showed that maximum H2 yield was observed at high Acetic-to-Butyric ratio. EG removal of 92.38±0.68%, in terms of COD, was achieved at HRT of 72hrs; however, this value was largely deteriorated to reach 13.74±4.46% at HRT of 18hrs. Strong effect of pH on hydrogen production was also observed. Thus, the pH values were dropped gradually to 5.23±0.19, with maximum corresponding hydrogen yield