Overcoming the calcification barrier: Enhanced power generation via acid pretreatment of calcified Pleurochrysis carterae biomass in membrane-less microbial fuel cells

Calcified cell walls impose structural limitations on the bioelectrochemical use of Pleurochrysis carterae (P.carterae), despite its high lipid content and CaCO₃ biomineralization capacity. In this study, P.carterae biomass was pretreated with 1–3% (v/v) H₂SO₄ for 30 min and fed to the anode of a membrane-less microbial fuel cell. Acid pretreatment increased the maximum power density from 420 to 1130 mW m⁻², corresponding to approximately a 2.7-fold increase. Electrochemical analyses showed that this improvement was associated with a decrease in internal resistance, with ohmic and charge transfer resistances reduced by 78% and 90%, respectively. CV and EIS results supported enhanced electron transfer after acid pretreatment. Microbial community analysis revealed that electroactive genera such as Shewanella sp. and Desulfovibrio sp. became more abundant under high-performance conditions. Overall, these findings indicate that acid pretreatment alleviates charge-transfer limitations, improves bioelectrochemical performance, and highlight calcified microalgae as a promising biomass source for energy production and carbon management.