Use of Biochar-Based Cathodes and Increase in the Electron Flow by Pseudomonas aeruginosa to Improve Waste Treatment in Microbial Fuel Cells

Abstract

In this paper, we tested the combined use of a biochar-based material at the cathode and of Pseudomonas aeruginosa strain in a single chamber, air cathode microbial fuel cells (MFCs) fed with a mix of shredded vegetable and phosphate buffer solution (PBS) in a 30% solid/liquid ratio. As a control system, we set up and tested MFCs provided with a composite cathode made up of a nickel mesh current collector, activated carbon and a single porous poly tetra fluoro ethylene (PTFE) diffusion layer. At the end of the experiments, we compared the performance of the two systems, in the presence and absence of P. aeruginosa, in terms of electric outputs. We also explored the potential reutilization of cathodes. Unlike composite material, biochar showed a life span of up to 3 cycles of 15 days each, with a pH of the feedstock kept in a range of neutrality. In order to relate the electric performance to the amount of solid substrates used as source of carbon and energy, besides of cathode surface, we referred power density (PD) and current density (CD) to kg of biomass used. The maximum outputs obtained when using the sole microflora were, on average, respectively 0.19 Wm−2kg−1 and 2.67 Wm−2kg−1, with peaks of 0.32 Wm−2kg−1 and 4.87 Wm−2kg−1 of cathode surface and mass of treated biomass in MFCs with biochar and PTFE cathodes respectively. As to current outputs, the maximum values were 7.5 Am−2 kg−1 and 35.6 Am−2kg−1 in MFCs with biochar-based material and a composite cathode. If compared to the utilization of the sole acidogenic/acetogenic microflora in vegetable residues, we observed an increment of the power outputs of about 16.5 folds in both systems when we added P. aeruginosa to the shredded vegetables. Even though the MFCs with PTFE-cathode achieved the highest performance in terms of PD and CD, they underwent a fouling episode after about 10 days of operation, with a dramatic decrease in pH and both PD and CD. Our results confirm the potentialities of the utilization of biochar-based materials in waste treatment and bioenergy production.

A New Pseudomonas aeruginosa Isolate Enhances Its Unusual 1,3-Propanediol Generation from Glycerol in Bioelectrochemical System

“…Several factors influence the performance of MFCs, including the electron transfer mechanism of the biocatalysts, substrate type and concentration, and reactor design [18]. Nastro et al (2021) [19] used P. aeruginosa ATCC 15,692 in an MFC fed with vegetable residues composed mainly of cellulose, lignin, and starch, and the maximum current obtained in the MFC was 32.9 A m −2 per kg of biomass. When glycerol is used as a substrate in MFCs with P. aeruginosa as biocatalysts, currents range from 0.63 to 418.3 mA m −2 (Table 1).…”

Bioelectrochemical cells as a green energy source for electrochemical treatment of water and wastewater

“…The MFC is a quickly evolving expertise that can treat wastewater and retrieve energy in the form of bioelectricity. MFCs can decompose a wide range of organic substances, allowing for treatment and resource recovery [15]. With external energy, bacteria may electrochemically convert inorganic carbon to biofuels and value-added chemicals such as biohydrogen, biomethane, acetic acid, and alcohols [13,16].…”