Hydrogen production using biocathode single-chamber microbial electrolysis cells fed by molasses wastewater at low temperature

Molasses is by-product from sugar beet process and commonly used as raw material for ethanol production. However, the molasses wastewater possesses high level of chemical oxygen demand (COD), which needs to be properly treated before discharge. In this work, MEC technology, a promising method for hydrogen production from organic waste, was utilized to produce H₂ from molasses wastewater. In this study, the feasibility of operating the MEC at low temperatures was evaluated since the average wastewater temperature in Harbin city is lower than 10 °C. In addition, the feasibility of using biocathode as an alternative to expensive platinum (Pt) as the cathode material was also examined. Both Pt catalyzed MECs and biocathodic MECs were operated at a low temperature of 9 °C. The overall hydrogen recovery of 72.2% (E_ap = 0.6 V) was obtained when the Pt catalyst was used. In contrast, when a cheaper catalyst (biocathode; E_ap = 0.6 V) was used, hydrogen can still be produced but at a lower overall hydrogen recovery of 45.4%. This study demonstrated that hydrogen could be generation from molasses wastewater at a low temperature using a cheaper cathode material (i.e., biocathode).