Critical assessment of biofilm and suspended growth reactor configurations for acidogenic biohydrogen production using wastewater as a function of redox microenvironment

•Biofilm and suspended-growth configuration were evaluated for H2 production.•Biofilm operation at pH 6 showed effective H2 production.•Higher acetate concentration correlated well with good H2 production.

Comprehensive experiments were designed to study the relative function of two bioreactor configurations viz., biofilm and suspended growth for dark-fermentative hydrogen (H2) production along with wastewater treatment at two varying feed pH conditions (6 and 7). Both the reactors were operated in sequencing batch mode using anaerobic inoculum after pretreatment (combined treatment: acid-shock, heat-shock and chemical-shock). Biofilm system showed efficient H2 production over the corresponding suspended growth operation at feeding pH 6. VFA profiles visualized high acetate fraction supporting feasible microenvironment for higher H2 production. Voltammogram profiles visualized significant variation in the bio-electrochemical behavior with the function of operating pH and reactor configuration. It can be inferred from this study that biofilm systems are efficient for H2 production particularly at acidiophilic microenvironment.

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