Geometric effect of honeycomb on the performance of the recirculation microbial fuel cells

Microbial fuel cells (MFCs) are recognized as a state-of-the-art technology that generates biochemical energy and converts it to electrical energy. MFCs include a series of metabolizing organic material from wastewater and allow its treatment while providing the opportunity to generate electricity. It is to be noted that the buffer used commonly in MFCs is relatively costly and quantified to have environmental impacts when applied in commercial wastewater treatment. To address the concern related to the buffer, this work proposes to evaluate a geometrical design of honeycomb whose inner diameters (0.4, 0.7, 1.2 cm) and lengths (2.5, 5 cm) were selected to replace the buffer. With the introduction of the honeycomb design, the study also aims to investigate its effect on the performance of recirculation within the MFCs. This is then evaluated under the optimal operational flow rate and pH level, which were already established by previous studies. The results have revealed that the optimal geometry of the honeycomb consists of a dimension with an inner diameter of 1.2 cm and a length of 5 cm. This combination of inner diameter and length of the honeycomb has yielded the highest power density for the MFC at 491 mW m⁻² when compared with the other cases. The findings of this study will be useful for the development of a cost-effective and environmentally friendly MFC when applied in commercial wastewater treatment in the future.