A dual-chamber microbial fuel cell with conductive film-modified anode and cathode and its application for the neutral electro-Fenton process

Challenges and recommendations for using membranes in wastewater-based microbial fuel cells for in situ Fenton oxidation for textile wastewater treatment

Wastewater-based microbial fuel cell is a promising green technology that can potentially be used to treat recalcitrant wastewater such as textile wastewater through

Arsenite oxidation and removal driven by a bio-electro-Fenton process under neutral pH conditions

The iron-catalyzed oxidation of arsenite (As(III)) associated with Fenton or Fenton-like reactions is one of the most efficient arsenic removal methods. However, the conventional chemical or electro-Fenton systems for the oxidation of As(III) are only efficient under acid conditions. In the present study, a cost-effective and efficient bio-electro-Fenton process was performed for As(III) oxidation in a dual-chamber microbial fuel cell (MFC) under neutral pH conditions. In such a system, the Fenton reagents, including H2O2 and Fe(II), were generated in situ by microbial-driven electro-reduction of O2 and γ-FeOOH, respectively, without an electricity supply. The results indicated that the process was capable of inducing As(III) oxidation with an apparent As(III) depletion first-order rate constant of 0.208 h(-1). The apparent oxidation current efficiency was calculated to be as high as 73.1%. The γ-FeOOH dosage in the cathode was an important factor in determining the system performance. Fourier-transform infrared spectroscopy (FT-IR) analysis indicated that As(V) was bound to the solid surface as a surface complex but not as a precipitated solid phase. The mechanism of bio-E-Fenton reaction for As(III) oxidation was also proposed. The bio-electro-Fenton system makes it potentially attractive method for the detoxification of As(III) from aqueous solution.

Anode-biofilm electron transfer behavior and wastewater treatment under different operational modes of bioelectrochemical system

Anode-biofilm electron transfer behavior was investigated during the advanced wastewater treatment process by three bioelectrochemical systems (BESs): microbial fuel cell (MFC), MFC operated under short circuit condition (MSC), and microbial electrolysis cell (MEC). Under different operational modes, current produced by the anode biofilm varied from 0.92, 4.15 to 8.21mA in the sequence of MFC, MSC and MEC, respectively. The cyclic voltammetry test on the anode biofilm suggested that the current generation was achieved via various bioelectroactive species with formal potentials at -0.473, -0.402 and -0.345V (vs. SCE). Gibbs free energy and charge transfer resistance data demonstrated that different amounts of available bioelectroactive species functioned in different BESs. The comparative investigation among MFC, MSC and MEC suggested that MEC was the only feasible operational mode for advanced wastewater treatment, because of its superior current generation capability.

Bacterial-fungal interactions enhance power generation in microbial fuel cells and drive dye decolourisation by an ex situ and in situ electro-Fenton process

In this work, the potential for sustainable energy production from wastes has been exploited using a combination fungus-bacterium in microbial fuel cell (MFC) and electro-Fenton technology. The fungus Trametes versicolor was grown with Shewanella oneidensis so that the bacterium would use the networks of the fungus to transport the electrons to the anode. This system generated stable electricity that was enhanced when the electro-Fenton reactions occurred in the cathode chamber. This configuration reached a stable voltage of approximately 1000 mV. Thus, the dual benefits of the in situ-designed MFC electro-Fenton, the simultaneous dye decolourisation and the electricity generation, were demonstrated. Moreover, the generated power was effectively used to drive an ex situ electro-Fenton process in batch and continuous mode. This newly developed MFC fungus-bacterium with an in situ electro-Fenton system can ensure a high power output and a continuous degradation of organic pollutants.

Microbial fuel cells and microbial electrolysis cells for the production of bioelectricity and biomaterials

Today's global energy crisis requires a multifaceted solution. Bioenergy is an important part of the solution. The microbial fuel cell (MFC) technology stands out as an attractive potential technology in bioenergy. MFCs can convert energy stored in organic matter directly into bioelectricity. MFCs can also be operated in the electrolysis mode as microbial electrolysis cells to produce bioproducts such as hydrogen and ethanol. Various wastewaters containing low-grade organic carbons that are otherwise unutilized can be used as feed streams for MFCs. Despite major advances in the past decade, further improvements in MFC power output and cost reduction are needed for MFCs to be practical. This paper analysed MFC operating principles using bioenergetics and bioelectrochemistry. Several major issues were explored to improve the MFC performance. An emphasis was placed on the use of catalytic materials for MFC electrodes. Recent advances in the production of various biomaterials using MFCs were also investigated.

Degradation of p-nitrophenol in a BES-Fenton system based on limonite

This study confirmed the feasibility of natural limonite working as the iron catalyst for the PNP wastewater treatment in the BES-Fenton system. After the start-up period of the BES-Fenton systems, air and limonite powder were injected into the cathode chamber as the original materials for manufacturing Fenton reagents of H₂O₂ and Fe(II) respectively. The experiment parameters like pH, external resistance, limonite dosage and initial PNP concentration were investigated in this research. The removal efficiency of PNP (0.25 mM) could achieve 96% in 6h under the optimal experimental conditions. A limonite dosage of 112 mg per 50 ml of PNP solution at 0.25 mM concentration each time could sustain 7 cycles of the BES-Fenton system operation with PNP removal efficiency >94%. This study suggests an efficiency and cost-effective approach for the PNP removal by using the natural limonite as the iron catalyst of the BES-Fenton system.

Bio-current as an indicator for biogenic Fe(II) generation driven by dissimilatory iron reducing bacteria

Microbial reduction of insoluble iron minerals by dissimilatory iron reducing bacteria (DIRB) is an important environment process in the iron biogeochemical cycle. We reported that the bio-current generated from oxidation of organic matter by these bacteria in the presence of iron oxides can be used as an indicator for microbial dissolution of insoluble iron oxides. Bioelectrochemical experiments were conducted to investigate the effects of the specific bacteria and the phase identity of iron oxides on bio-current generation by recording the current response as a result of a poised constant potential. Experimental results indicated that the bio-current generation can be greatly enhanced by iron oxide addition under all the conditions varying in the type of pure culture or iron oxide. The increase in the bio-current was linearly correlated with the increased concentration of biogenic Fe(II) detected either by chemical analysis or cyclic voltammetry (CV) tests. This can be understood based on the proposed mechanism that the Fe(II)/Fe(III) couple functions as the electron mediator shuttling electrons from the microbes to the electrodes.