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.RESULTSThe 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. (c) 2021 Society of Chemical Industry (SCI).