Modelling of a bioelectrochemical system for metal‐polluted wastewater treatment and sequential metal recovery

BACKGROUND This work develops a simplified mathematical model to predict the performance of a bioelectrochemical system (BES), first working as a microbial fuel cell (MFC) and then as a microbial electrolysis cell (MEC), for the recovery of dissolved metals (Fe, Cu, Sn, and Ni) from simulated industrial wastewater. Experimental data from a previous work were used as starting points for mathematical modelling. Wastewater was used as the catholyte and contained Cu2+ and Fe3+ (500 mg L−1) as well as Sn2+ and Ni2+ (50 mg L−1), while the anolyte was composed of sodium acetate. Two mixed microbial populations were considered in the anode compartment (electrogenic and non‐electrogenic biomass). Dissolved metal ions were the electron acceptors in the electrogenic mechanism: Cu2+ and Fe3+ under MFC mode and then Fe2+, Ni2+, and Sn2+ under MEC mode. RESULTS The model predicted the organic substrate and microbial biomass (anode chamber) and Fe3+ and Cu2+ (cathode chamber) concentrations during MFC operation. Monod kinetic and stoichiometric parameters were calibrated, and it was observed that most of the organic substrate underwent a non‐electrogenic mechanism. The generation of electric current until electron acceptors were removed was also predicted. Concentration profiles and first‐rate constant values for the decreased Sn2+, Ni2+, and Fe2+ concentrations during the subsequent MEC operation were also obtained. The model was then used for simulations under different experimental conditions. CONCLUSION This work offers a single grey‐box model proposal that is easy to implement, and it can be used as a practical tool for testing the removal of dissolved metals in BESs. © 2021 Society of Chemical Industry (SCI).