Two-Stage Process for Energy Valorization of Cheese Whey through Bio-Electrochemical Hydrogen Production Coupled with Microbial Fuel Cell

The present work investigates a two-stage process scheme for cheese whey valorization through energy recovery in different forms by means of bio-electrochemical systems. The first stage consisted of an integrated bio-electrochemical process for H₂ and electricity production. This combined dark fermentation with an electrochemical system with the aim of overcoming the typical thermodynamic/biochemical limitations of fermentation and enhancing H₂ recovery. The second treatment stage involved a single-chamber microbial fuel cell, featuring an innovative configuration consisting of four air cathodes with fly ash as the oxygen reduction catalyst. The bio-electrochemical process performed in the first stage achieved promising results, displaying a three-times higher H₂ production yield compared to conventional dark fermentation. In addition, the experiments using the MFC in the second stage were found to successfully exploit the effluent from the first stage, with COD removal yields of 86% ± 8% and energy recovery with a maximum current output of 1.6 mA and a maximum power density of 1.2 W/m³.