Enhancing the biological hydrogen production in a novel way of using co-substrates

Abstract

Microbial electrolysis cell (MEC) is a potential technology to meet the increasing interest in finding new sources of energy that will not harm the environment. MEC is an alternative energy conversion technology for the production of biofuels. It is possible to produce hydrogen by fermenting biogenous wastes with hydrogen-producing bacteria. This study investigated the biohydrogen production from co-substrates using electrogenic bacteria such as Escherichia coli, Salmonella bongori, and Shewanella oneidensis in pure culture and as a co-culture, which has the potential to be used as co-substrate in MECs. Briefly, 150 mL working-volume reactors were constructed for batch biohydrogen production. The hydrogen production rate (HPR) from the co-substrate was maximum at a ratio of 75:25 g/L with a co-culture of 2.35 mL/(L h). Fabricated a single-chamber membrane-free microelectrolysis cell to evaluate the power density, current density, voltage, HPR, chemical oxygen demand (COD) removal efficiency and Columbic efficiency. Scanning electron microscope (SEM) imaging confirmed the binding of electrogenic bacteria to anode and cathode. The efficiency of electrical conductivity of MEC was analyzed by three different electrodes, namely, nickel, copper and aluminum. The HPR was high using nickel when compared to the other two electrodes. The HPR of a single chamber using a nickel electrode was 2.8 HPR ml/L H₂ d⁻¹ and provided a power density of 17.7 mW/m² at pH 7. This study suggests that the nickel cathode in a single chamber could be a promising sustainable source for stable power generation.

Graphical abstract