This study examined the removal of methylene blue and glucose as substrate and co-substrate respectively, from an aqueous solution by the application of a dual cell fungal-based microbial fuel cell. The choice of fungus (Trichoderma harzianum) was based on its metabolic ability to degrade organic compounds, especially those containing aromatic rings. To do so, two types of carbon cloths fixed on platinum rods were tested as anode, cathode and supports for fungi growth, KIP and CSV from Decarb company (France). Potassium ferricyanide was used as electron acceptor and cathodic compartment was aerated with dioxygen to regenerate ferrocyanide into ferricyanide. These two electrodes, with various characteristics, showed different performances in the removal and microbial fuel cell efficiency. Kinetics of methylene blue removal followed a pseudo-first-order model with a half-time of 4 h for CSV and 4.7 h for KIP with same methylene blue initial concentration of 100 mg L−1. Considering the sorption experiments, it could be observed that the methylene blue was absorbed faster by the CSV electrode (a sorption half-time of 4.5 h) compared to the KIP (with a half-time of 29.6 h). As the quantity of absorbed methylene blue was higher in KIP due to its greater thickness (530 µm for KIP and 235 µm for CSV), and higher hydrophobicity. Moreover, KIP, being more hydrophobic than CSV, entrapped a larger quantity of fungal mass. Therefore, the microbial fuel cell working with KIP electrodes was more efficient with higher maximum power density φ. The microbial fuel cell was optimized by a previous step of methylene blue saturation of the carbon cloths anode before use in microbial fuel cell to eliminate methylene blue sorption by carbon cloths. The obtained φ values for KIP were largely increased and were higher compared to those usually encountered in the bibliography: φs = 101 mW m−2 of the electrode (per surface area of anode) and φv’ = 1386 mW m−3 of treated volume in open circuit and φs = 68 mW m−2 and φv’ = 1,267,000 mW m−3 in debiting mode (conditions R = 200 Ohm). The chosen resistance value was that which gave the highest power production. These results highlight the importance of carbone cloth anode characteristics (thickness, density, hydrophobicity, pre-saturation by the substrate) on the microbial fuel cell performances. They present new prospects for microbial fuel cell systems to obtain significant enhancement of the energy recovery efficiency. Graphical abstract

Methylene blue removal by a dual-chamber fungal-based microbial fuel cell with Trichoderma harzianum

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发表日期：

2025年7月10日

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Sébastien Votat,
Maxime Pontié,
Mehri Shabani,
Laurent Lebrun

摘要

This study examined the removal of methylene blue and glucose as substrate and co-substrate respectively, from an aqueous solution by the application of a dual cell fungal-based microbial fuel cell. The choice of fungus (Trichoderma harzianum) was based on its metabolic ability to degrade organic compounds, especially those containing aromatic rings. To do so, two types of carbon cloths fixed on platinum rods were tested as anode, cathode and supports for fungi growth, KIP and CSV from Decarb company (France). Potassium ferricyanide was used as electron acceptor and cathodic compartment was aerated with dioxygen to regenerate ferrocyanide into ferricyanide. These two electrodes, with various characteristics, showed different performances in the removal and microbial fuel cell efficiency. Kinetics of methylene blue removal followed a pseudo-first-order model with a half-time of 4 h for CSV and 4.7 h for KIP with same methylene blue initial concentration of 100 mg L⁻¹. Considering the sorption experiments, it could be observed that the methylene blue was absorbed faster by the CSV electrode (a sorption half-time of 4.5 h) compared to the KIP (with a half-time of 29.6 h). As the quantity of absorbed methylene blue was higher in KIP due to its greater thickness (530 µm for KIP and 235 µm for CSV), and higher hydrophobicity. Moreover, KIP, being more hydrophobic than CSV, entrapped a larger quantity of fungal mass. Therefore, the microbial fuel cell working with KIP electrodes was more efficient with higher maximum power density φ. The microbial fuel cell was optimized by a previous step of methylene blue saturation of the carbon cloths anode before use in microbial fuel cell to eliminate methylene blue sorption by carbon cloths. The obtained φ values for KIP were largely increased and were higher compared to those usually encountered in the bibliography: φ_s = 101 mW m⁻² of the electrode (per surface area of anode) and φ_v’ = 1386 mW m⁻³ of treated volume in open circuit and φ_s = 68 mW m⁻² and φ_v’ = 1,267,000 mW m⁻³ in debiting mode (conditions R = 200 Ohm). The chosen resistance value was that which gave the highest power production. These results highlight the importance of carbone cloth anode characteristics (thickness, density, hydrophobicity, pre-saturation by the substrate) on the microbial fuel cell performances. They present new prospects for microbial fuel cell systems to obtain significant enhancement of the energy recovery efficiency.

Graphical abstract