A two-stage process for hydrogen production from cheese whey: Integration of dark fermentation and biocatalyzed electrolysis

This paper explores the potential of a two-stage process (fermentative + biocatalyzed electrolysis) to reduce the organic load of an industrial waste stream (cheese whey) in parallel with hydrogen production. Overall, the combined process helped to significantly reduce the chemical oxygen demand (COD) of the effluent, while producing hydrogen at a maximum yield of 94.2 L H2 kgvs−1. The low pH of the fermentative effluent fed into the bioelectrochemical reactor helped to control methanogenic and homoacetogenic activity during the second stage of the treatment. However, this acid stream needed to be diluted and amended with salts and acetate to avoid the collapse of hydrogen production rate. Therefore, practical application of a two stage process for the treatment of cheese whey would require the existence of a secondary waste stream for dilution of the acidified effluent, thus balancing its nutrients composition prior to feeding into the bioelectrochemical system.