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Abstract
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The rising demand for sustainable wastewater treatment and renewable energy highlights microalgae microbial fuel cells (MMFCs) as a promising dual-function technology. However, microbial interactions at the anode are still insufficiently understood and limit system optimization. This study aims to enhance MMFC performance by optimizing bacterial inoculation factors that influence microbial activity and overall system efficiency. A defined co-culture of Shewanella oneidensis MR-1 and Bacillus subtilis was employed as the anodic consortium, while a native strain of Chlorococcum sp. /Kh.A.d2 was used at the cathode to provide oxygen via photosynthesis. Response Surface Methodology (RSM) using a small Central Composite Design (CCD) was applied to evaluate the effects of bacterial optical density (OD), total inoculation volume, and co-culture ratio on MMFC efficiency. Under optimized conditions, the MMFC achieved an open-circuit voltage (OCV) of 0.887 V, a maximum power density of 83,312.26 mW/m 2 , and 90 % chemical oxygen demand (COD) removal efficiency. These results were obtained at low OD and volume levels, with a high ratio of S. oneidensis to B. subtilis, achieving a desirability index of 0.95, which confirmed the robustness of the optimized conditions. The findings emphasize the critical role of controlling the initial microbial inoculum characteristics in improving electron transfer, metabolic effi
ciency, and system output. This study proposes a scalable microbial approach to advancing MMFCs as integrated platforms for clean energy generation and wastewater treatment.
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