摘要
Microalgae are employed in the cathode of microbial fuel cells as natural O₂ generators utilized in the reduction reaction, forming microalgal microbial fuel cells (mMFCs). However, microalgae with high settling tendencies often exhibit a gradual decline in metabolic activity and voltage generation. In this study, six mMFC configurations were evaluated, including S (without stirring) and + S (with stirring), using Chlorella sp. (+Chl), Spirulina sp. (+Spi), and a control without microalgae (−M). The integration of magnetic beads within the cathode facilitated uniform distribution of microalgal cells, nutrients, light, CO₂, and O₂, while promoting biofilm formation on the electrode through exopolysaccharide secretion, which enhanced oxidation–reduction reactions and improved power generation. Optical density, dry biomass, chlorophyll content, and CO₂ fixation were analyzed. Stirred systems (+S + Chl and + S + Spi) demonstrated improved cell adhesion and higher voltage outputs of 564.7 mV and 448.7 mV, respectively, with corresponding power densities of 80 and 33 mV/m2, and current densities of 220 and 150 mA/m2. Cyclic voltammetry revealed a response current of 15 mA, confirming that magnetic bead-assisted mixing is a simple yet effective strategy for enhancing bioelectric performance in mMFCs. Large-scale systems with a stirred cathode configuration will offer a simple, less energy-intensive, and more productive mechanism for enhanced bioelectricity generation and biomass production, paving the way forward for the future.
[Display omitted]
•Higher settling velocity of microalgae reduces growth and performance.•Unsettling enhanced light availability, growth, ORR, and biomass.•mMFC and MCC together possess numerous environmental supporting applications.•The maximum PD and CD were 80 mV/m2 and 220 mA/m3, respectively.