Evolving Microbial Communities in Cellulose-Fed Microbial Fuel Cell

Boosting o-xylene removal and power generation in an airlift microbial fuel cell system

Microbial fuel cells (MFCs) are widely acknowledged to be a promising eco-friendly abatement technology of pollutants, and are capable of generating electricity. However, the poor mass transfer and reaction rate in MFCs significantly decrease their treatment capacity for contaminants, especially hydrophobic substances. The present work developed a novel MFC integrated with an airlift (ALR) reactor using a polypyrrole modified anode to promote the bioaccessibility of gaseous o-xylene and attachment of microorganisms. The results indicated that the established ALR-MFC system showed excellent elimination capability, with removal efficiency exceeding 84% even at high o-xylene concentration (1600 mg m^-3). The maximum output voltage of 0.549 V and power density of 13.16 mW m^-2 obtained by the Monod-type model were approximately twice and sixfold higher than that of a conventional MFC, respectively. According to the microbial community analysis, the superior performances of the ALR-MFC in terms of o-xylene removal and power generation were mainly ascribed to the enrichment of degrader (i.e. Shinella) and electrochemical active bacteria (i.e. Proteiniphilum). Moreover, the electricity generation of the ALR-MFC did not decrease at a high O₂ concentration, as O₂ was conducive to o-xylene degradation and electron release. The supplication of an external carbon source such as sodium acetate (NaAc) was conducive to increasing output voltage and coulombic efficiency. The electrochemical analysis revealed that released electrons can be transmitted with the action of NADH dehydrogenase to OmcZ, OmcS, and OmcA outer membrane proteins via a direct or indirect pathway, and ended up transferring to the anode directly.

Recent progress in microbial fuel cells using substrates from diverse sources

Increasing untreated environmental outputs from industry and the rising human population have increased the burden of wastewater and other waste streams on the environment. The most prevalent wastewater treatment methods include the activated sludge process, which requires aeration and is, therefore, energy and cost-intensive. The current trend towards a circular economy facilitates the recovery of waste materials as a resource. Along with the amount, the complexity of wastewater is increasing day by day. Therefore, wastewater treatment processes must be transformed into cost-effective and sustainable methods. Microbial fuel cells (MFCs) use electroactive microbes to extract chemical energy from waste organic molecules to generate electricity via waste treatment. This review focuses use of MFCs as an energy converter using wastewater from various sources. The different substrate sources that are evaluated include industrial, agricultural, domestic, and pharmaceutical types. The article also highlights the effect of operational parameters such as organic load, pH, current, and concentration on the MFC output. The article also covers MFC functioning with respect to the substrate, and the associated performance parameters, such as power generation and wastewater treatment matrices, are given. The review also illustrates the success stories of various MFC configurations. We emphasize the significant measures required to fill in the gaps related to the effect of substrate type on different MFC configurations, identification of microbes for use as biocatalysts, and development of biocathodes for the further improvement of the system. Finally, we shortlisted the best performing substrates based on the maximum current and power, Coulombic efficiency, and chemical oxygen demand removal upon the treatment of substrates in MFCs. This information will guide industries that wish to use MFC technology to treat generated effluent from various processes.

Effects of bioelectricity generation processes on methane emission and bacterial community in wetland and carbon fate analysis

Wetlands are an important carbon sink for greenhouse gases (GHGs), and embedding microbial fuel cell (MFC) into constructed wetland (CW) has become a new technology to control methane (CH4) emission. Rhizosphere anode CW-MFC was constructed by selecting rhizome-type wetland plants with strong hypoxia tolerance, which could provide photosynthetic organics as alternative fuel. Compared with non-planted system, CH4 emission flux and power output from the planted CW-MFC increased by approximately 0.48 ± 0.02 mg/(m2·h) and 1.07 W/m3, respectively. The CH4 emission flux of the CW-MFC operated under open-circuit condition was approximately 0.46 ± 0.02 mg/(m2·h) higher than that under closed-circuit condition. The results indicated that plants contributed to the CH4 emission from the CW-MFC, especially under open-circuit mode conditions. The CH4 emission from the CW-MFC was proportional to external resistance, and it increased by 0.67 ± 0.01 mg/(m2·h) when the external resistance was adjusted from 100 to 1000 Ω. High throughput sequencing further showed that there was a competitive relationship between electrogenic bacteria and methanogens. The flora abundance of electrogenic bacteria was high, while methanogens mainly consisted of Methanothrix, Methanobacterium and Methanolinea. The form and content of element C were analysed from solid phase, liquid phase and gas phase. It was found that a large amount of carbon source (TC = 254.70 mg/L) was consumed mostly through microbial migration and conversion, and carbon storage and GHGs emission accounted for 60.38% and 35.80%, respectively. In conclusion, carbon transformation in the CW-MFC can be properly regulated via competition of microorganisms driven by environmental factors, which provides a new direction and idea for the control of CH4 emission from wetlands.

Microbial fuel cells a state-of-the-art technology for wastewater treatment and bioelectricity generation

Wastewater treatment and electricity generation have been the major concerns for the last few years. The scarcity of fossil fuels has led to the development of unconventional energy resources that are pollution-free. Microbial fuel cell (MFC) is an environmental and eco-friendly technology that harvests energy through the oxidation of organic substrates and transform into the electric current with the aid of microorganisms as catalysts. This review presents power output and colour removal values by designing various configurations of MFCs and highlights the importance of materials for the fabrication of anode and cathode electrodes playing vital roles in the formation of biofilm and redox reactions taking place in both chambers. The electron transfer mechanism from microbes towards the electrode surface and the generation of electric current are also highlighted. The effect of various parameters affecting the cell performance such as type and amount of substrate, pH and temperature maintained within the chambers have also been discussed. Although this technology presents many advantages, it still needs to be used in combination with other processes to enhance power output.

Microbial fuel cells for bioelectricity production from waste as sustainable prospect of future energy sector

Microbial fuel cell (MFC) is lauded for its potentials to solve both energy crisis and environmental pollution. Technologically, it offers the capability to harness electricity from the chemical energy stored in the organic substrate with no intermediate steps, thereby minimizes the entropic loss due to the inter-conversion of energy. The sciences underneath such MFCs include the electron and proton generation from the metabolic decomposition of the substrate by microbes at the anode, followed by the shuttling of these charges to cathode for electricity generation. While its promising prospects were mutually evinced in the past investigations, the upscaling of MFC in sustaining global energy demands and waste treatments is yet to be put into practice. In this context, the current review summarizes the important knowledge and applications of MFCs, concurrently identifies the technological bottlenecks that restricted its vast implementation. In addition, economic analysis was also performed to provide multiangle perspectives to readers. Succinctly, MFCs are mainly hindered by the slow metabolic kinetics, sluggish transfer of charged particles, and low economic competitiveness when compared to conventional technologies. From these hindering factors, insightful strategies for improved practicality of MFCs were formulated, with potential future research direction being identified too. With proper planning, we are delighted to see the industrialization of MFCs in the near future, which would benefit the entire human race with cleaner energy and the environment.

Lignocellulose, Cellulose and Lignin as Renewable Alternative Fuels for Direct Biomass Fuel Cells

In recent years the use of renewable sources, such as lignocellulosic biomass (LCB), as the fuel for various types of fuel cells received growing interest. Different types of fuel cells, that is, operated at low temperatures (T<100 °C; microbial fuel cells (MFC), alkaline (AFCs) and flow fuel cells (FFCs)), intermediate temperatures (T in the range 150-300 °C, proton-conducting inorganic-organic composite membrane fuel cells), and high temperatures (T≥500 °C, direct carbon fuel cells (DCFCs)), have been used for the conversion of the chemical energy in LCB to electrical energy. The economic advantage of the direct use of LCB consists of avoiding the acid hydrolysis of cellulose to glucose for low-temperature fuel cells and the pretreatment at high temperatures necessary to convert biomass to biochar (pyrolysis) in the case of high-temperature fuel cells. In this Review, the characteristics of direct biomass fuel cells are presented and their performance is compared with that of indirect biomass fuel cells fed with glucose (low-temperature fuel cells) and biochar (high-temperature fuel cells).

Engineering S. oneidensis for Performance Improvement of Microbial Fuel Cell-a Mini Review

Microbial fuel cell (MFC) is a promising technology that utilizes exoelectrogens cultivated in the form of biofilm to generate power from various types of sources supplied. A metal-reducing pathway is utilized by these organisms to transfer electrons obtained from the metabolism of substrate from anaerobic respiration extracellularly. A widely established model organism that is capable of extracellular electron transfer (EET) is Shewanella oneidensis. This review highlights the strategies used in the transformation of S. oneidensis and the recent development of MFC in terms of intervention through genetic modifications. S. oneidensis was genetically engineered for several aims including the study on the underlying mechanisms of EET, and the enhancement of power generation and wastewater treating potential when used in an MFC. Through engineering S. oneidensis, genes responsible for EET are identified and strategies on enhancing the EET efficiency are studied. Overexpressing genes related to EET to enhance biofilm formation, mediator biosynthesis, and respiration appears as one of the common approaches.

The Utility of Electrochemical Systems in Microbial Degradation of Polycyclic Aromatic Hydrocarbons: Discourse, Diversity and Design

Polycyclic aromatic hydrocarbons (PAHs), especially high molecular weight PAHs, are carcinogenic and mutagenic organic compounds that are difficult to degrade. Microbial remediation is a popular method for the PAH removal in diverse environments and yet it is limited by the lack of electron acceptors. An emerging solution is to use the microbial electrochemical system, in which the solid anode is used as an inexhaustible electron acceptor and the microbial activity is stimulated by biocurrent in situ to ensure the PAH removal and avoid the defects of bioremediation. Based on the extensive investigation of recent literatures, this paper summarizes and comments on the research progress of PAH removal by the microbial electrochemical system of diversified design, enhanced measures and functional microorganisms. First, the bioelectrochemical degradation of PAHs is reviewed in separate and mixed PAH degradation, and the removal performance of PAHs in different system configurations is compared with the anode modification, the enhancement of substrate and electron transfer, the addition of chemical reagents, and the combination with phytoremediation. Second, the key functional microbiota including PAH degrading microbes and exoelectrogens are overviewed as well as the reduced microbes without competitive advantage. Finally, the typical representations of electrochemical activity especially the internal resistance, power density and current density of systems and influence factors are reviewed with the correlation analysis between PAH removal and energy generation. Presently, most studies focused on the anode modification in the bioelectrochemical degradation of PAHs and actually more attentions need to be paid to enhance the mass transfer and thus larger remediation radius, and other smart designs are also proposed, especially that the combined use of phytoremediation could be an eco-friendly and sustainable approach. Additionally, exoelectrogens and PAH degraders are partially overlapping, but the exact functional mechanisms of interaction network are still elusive, which could be revealed with the aid of advanced bioinformatics technology. In order to optimize the efficacy of functional community, more advanced techniques such as omics technology, photoelectrocatalysis and nanotechnology should be considered in the future research to improve the energy generation and PAH biodegradation rate simultaneously.

Single-Chamber Microbial Fuel Cells’ Behavior at Different Operational Scenarios

A Microbial Fuel Cell (MFC) is a process in which a microorganism respires and captures the electrons that normally passes through the electron transport system of the organism and produces electricity. This work intends to present the different operating parameters affecting the efficiency of a Microbial Fuel Cell (MFC) process. To study the performance of the process, various materials for the cathode and anode rods with similar size and chape including, copper, aluminum, carbon cloth, steel and brass were considered to determine the combination that leads to the best results. Moreover, different oxidizing agents such as Copper Sulphate and Potassium Hexacyanoferrate were considered. Furthermore, the effects of shapes, sizes and distance between electrodes on the current and voltage were investigated. The power outputs between electrochemical and microbial cells were recorded. In addition, the power, whether expressed as voltage or current, was measured at different conditions and different cell combinations. The power is directly related to the area, volume of the bacterial solution and supplying air and stirring.

Enhanced volatile fatty acid production from sago hampas by Clostridium beijerinckii SR1 for bioelectricity generation using microbial fuel cells

Sago hampas is a starch-based biomass from sago processing industries consisted of 58% remaining starch. This study has demonstrated the bioconversion of sago hampas to volatile fatty acids (VFAs) by Clostridium beijerinckii SR1 via anaerobic digestion. Higher total VFAs were obtained from sago hampas (5.04 g/L and 0.287 g/g) as compared to commercial starch (5.94 g/L and 0.318 g/g). The physical factors have been investigated for the enhancement of VFAs production using one-factor-at-a-time (OFAT). The optimum condition; 3% substrate concentration, 3 g/L of yeast extract concentration and 2 g/L of ammonium nitrate enhanced the production of VFAs by 52.6%, resulted the total VFAs produced is 7.69 g/L with the VFAs yield of 0.451 g/g. VFAs hydrolysate produced successfully generated 273.4 mV of open voltage circuit and 61.5 mW/m² of power density in microbial fuel cells. It was suggested that sago hampas provide as an alternative carbon feedstock for bioelectricity generation.

Application of slow-release carbon sources embedded in polymer for stable and extended power generation in microbial fuel cells

Stable and long-term power output is a prerequisite for the application of the energy recovered from microbial fuel cells (MFCs). In this study, a novel fuel supplying strategy based on slow-release carbon embedded in polymer gels was attempted in MFCs aimed to achieve a sustainable power generation. Polymer gels containing starch acetate as the carbon source (40% (w/w)) were prepared, and the effects of its loading dosage on power generation and microbial community structure were investigated. Results showed that the MFCs once fed with 20.0 g/L, 37.5 g/L and 55.0 g/L polymer gels attained a long-term power generation periods of 110, 140 and 170 days, respectively, with a maximum power density of 386-427 mW/m². The MFC with a medium loading dosage (37.5 g/L polymer gels) performed best. MFCs fed with the slow-release carbon enriched a distinct microbial community comparing to the control MFC with acetate as the carbon source, with the genera Geobacter, Sphaerochaeta, Christensenellaceae, Aminiphilus and Proteiniphilum significantly enriched on the anode electrode, and Sphaerochaeta, Proteiniphilum and Bacteroidetes in the anolyte. This carbon source providing method will promote the application of MFCs as a sustainable and stable power source for environmental monitoring and remediation.

Wood-Based Panel Industry Wastewater Meets Microbial Fuel Cell Technology

Although the wood-based panel industry is not considered to be a water-consuming sector, it generates ca. 600 M m³ of wastewater every year on a global scale. The wastewater is usually highly polluted and environmentally toxic even after dilution. Common wastewater treatment techniques require high-energy input or addition of various chemicals to the treated wastewater, which cause secondary pollution and production of toxic sludge. Microbial fuel cells (MFCs) have become an attractive technology, allowing for zero-energy treatment of various types of wastewater with simultaneous production of electric current. Recent investigations have shown that MFCs can also be utilized for sustainable treatment and energy production from the wastewater generated by the wood-based panel industry. This article contains a critical summary of the investigations in this field as well as a discussion of the research needed and perspectives for the future.

Individual and combined effects of magnetite addition and external voltage application on anaerobic digestion of dairy wastewater

Direct interspecies electron transfer (DIET) between exoelectrogenic fatty acid oxidizers and electrotrophic methanogens plays an important role in keeping the overall anaerobic digestion (AD) process well-balanced. This study examined the individual and combined effects of two different DIET-promoting strategies, i.e., magnetite addition (20 mM Fe) and external voltage application (0.6 V), in continuous digesters treating dairy wastewater. Although the strategies were both effective in enhancing the process performance and stability, adding magnetite had a much greater stimulatory effect. External voltage contributed little to the methane yield, and the digester with magnetite addition alone achieved stable performance, comparable to that of the digester where both strategies were combined, at short hydraulic retention times (down to 7.5 days). Diverse (putative) electroactive microorganisms were significantly enriched under DIET-promoting conditions, particularly with magnetite addition. The overall results suggest that magnetite addition could effectively enhance AD performance and stability by promoting DIET-based electro-syntrophic microbial interactions.

Changes in the gut microbiome and enzymatic profile of Tenebrio molitor larvae biodegrading cellulose, polyethylene and polystyrene waste

Recent studies have demonstrated the ability of mealworm (Tenebrio molitor) for plastic degradation. This study is focused on changes in microbiome structure depending on diets. Microbial community obtained from oat and cellulose diet formed similar group, two kinds of polyethylene formed another group, while polystyrene diet showed the highest dissimilarity. The highest relative abundance of bacteria colonizing gut was in PE-oxodegradable feeding, nevertheless all applied diets were higher in comparison to oat. Dominant phyla consisted of Proteobacteria, Bacteroides, Firmicutes and Actinobacteria, however after PS feeding frequency in Planctomycetes and Nitrospirae increased. The unique bacteria characteristic for cellulose diet belonged to Selenomonas, while Pantoea were characteristic for both polyethylene diets, Lactococcus and Elizabethkingia were unique for each plastic diet, and potential diazotropic bacteria were characteristic for polystyrene diet (Agrobacterium, Nitrosomonas, Nitrospira). Enzymatic similarity between oatmeal and cellulose diets, was shown. All three plastics diet resulted in different activity in both, digestive tract and bacteria. The enzymes with the highest activity were included phosphatases, esterases, leucine arylamidase, β-galactosidase, β-glucuronidase, α-glucosidase, β-glucosidase, chitinase, α-mannosidase and α-fucosidase. The activity of digestive tract was stronger than cultured gut bacteria. In addition to known polyethylene degradation methods, larvae may degrade polyethylene with esterase, cellulose and oatmeal waste activity is related with the activity of sugar-degrading enzymes, degradation of polystyrene with anaerobic processes and diazotrophs.

High performance of integrated vertical-flow constructed wetland for polishing low C/N ratio river based on a pilot-scale study in Hangzhou, China

We investigated the treatment efficiency of micro-polluted NO₃^--dominated river water with low C/N ratio by five parallel pilot-scale IVCWs with different plant and substrate collocation. When the mean concentration was 2.24 and 0.193 mg L^-1 in influent, IVCWs achieved an average (mass) removal rate of (0.09 g m^-2 day^-1) 46.8% and (0.77 g m^-2 day^-1) 62.3% for TN and TP, respectively, during 1 year of operation. Water quality was significantly improved from grade V to meet the criterion of grade IV of surface water. Through the comparison of removal rate by different IVCWs, we found that lack of carbon sources in influent limited the denitrification in the middle and bottom layers (ML, BL) of IVCW. Zeolites deployed in the upper layer (UL) of IVCW reduced the overall N removal efficiency compared with gravels, due to a stronger nitrification but weaker denitrification. Canna indica (C. indica) was superior to Arundo donax (A. donax) and Thalia dealbata (T. dealbata) for N removal in the UL of IVCW due to higher aboveground biomass accumulation and microbial removal during the first 10 months. Stronger nitrification and denitrification were simultaneously facilitated near the rhizosphere of C. indica. When entered into Dec., A. donax performed higher N removal efficiency than the other two species. The internal replenishment of peats in the ML as carbon sources significantly improved N and P removal efficiency. Zeolites with stronger capacity of ammonium (NH₄⁺) adsorption was more in favor of anammox in the BL, when compared with roseites, but both of them were not conducive to the growth of denitrifiers. However, the deployment of shale ceramisites obtained an opposite result. Gemmata and Pirellula as anammox bacteria were more enriched in the zeolite layer, whereas some anaerobic denitrifiers (Corynebacterium and Paludibacter) and heterotrophic denitrifiers including Bacillus, Geobacter, Pseudomonas, and Lactococcus were more found in shale ceramisite. Supply of peats as carbon sources in the ML was beneficial for the adhesion of anammox bacteria and denitrifiers in the BL of shale ceramisites. An ideal model composed of C. indica + A. donax (DFU)-gravel (UL)-anthracite+peat (ML)-zeolite+shale ceramsite (BL)-Acorus calamus (UFU) was proposed for treating this type of river water to achieve high efficiency.

Is there a Function for a Sex Pheromone Precursor?

Functional coupling and comparative genomics analysis have been applied to study functional associations of orthologs of enterococcal cAD1 sex pheromone (P13268) known to be responsible for biofilm formation, conjugative plasmid transfer and spreading of bacterial antibiotics resistance. cAD1 peptide pheromone is released from the membrane lipoprotein with the peptide precursor encoded by a gene cad (tr|C2JQE7). Our analysis of genomic neighbourhood of cad and motifs of the encoded polypeptide and its orthologs suggests a close functional association between cAD1 and ApbE protein (Q82Z24), a FMN insertion and trafficking facilitator. The cad and apbE orthologs were coupled in the genomes and ApbE-specific motifs for FMN covalent attachment were identified in cad-encoded protein sequence and its orthologs. These findings suggest a potential role of FMN-based reductase function of the cAD1 lipoprotein precursor in its processing and release of the active sex pheromone peptide. They may lead to a new approach in prevention of antibiotic resistance spread via targeting sex pheromone processing chaperones or by suppression of the FMN availability and covalent binding. This methods can be also applied to a controlled evolution of bacterial pathogenicity in microbial fuel cells, as the findings suggest the crosstalk between bacterial pathogenicity and bacterial electro-activity.

Effects of Polymer Matrices and Carbon Nanotubes on the Generation of Electric Energy in a Microbial Fuel Cell

The anode of a microbial fuel cell (MFC) was formed on a graphite electrode and immobilized Gluconobacter oxydans VKM-1280 bacterial cells. Immobilization was performed in chitosan, poly(vinyl alcohol) or N-vinylpyrrolidone-modified poly(vinyl alcohol). Ethanol was used as substrate. The anode was modified using multiwalled carbon nanotubes. The aim of the modification was to create a conductive network between cell lipid membranes, containing exposed pyrroloquinoline quinone (PQQ)-dependent alcoholdehydrogenases, and the electrode to facilitate electron transfer in the system. The bioelectrochemical characteristics of modified anodes at various cell/polymer ratios were assessed via current density, power density, polarization curves and impedance spectres. Microbial fuel cells based on chitosan at a matrix/cell volume ratio of 5:1 produced maximal power characteristics of the system (8.3 μW/cm²) at a minimal resistance (1111 Ohm cm²). Modification of the anode by multiwalled carbon nanotubes (MWCNT) led to a slight decrease of internal resistance (down to 1078 Ohm cm²) and to an increase of generated power density up to 10.6 μW/cm². We explored the possibility of accumulating electric energy from an MFC on a 6800-μF capacitor via a boost converter. Generated voltage was increased from 0.3 V up to 3.2 V. Accumulated energy was used to power a Clark-type biosensor and a Bluetooth transmitter with three sensors, a miniature electric motor and a light-emitting diode.

Fungi-Based Microbial Fuel Cells

Fungi are among the microorganisms able to generate electricity as a result of their metabolic processes. Throughout the last several years, a large number of papers on various microorganisms for current production in microbial fuel cells (MFCs) have been published; however, fungi still lack sufficient evaluation in this regard. In this review, we focus on fungi, paying special attention to their potential applicability to MFCs. Fungi used as anodic or cathodic catalysts, in different reactor configurations, with or without the addition of an exogenous mediator, are described. Contrary to bacteria, in which the mechanism of electron transfer is pretty well known, the mechanism of electron transfer in fungi-based MFCs has not been studied intensively. Thus, here we describe the main findings, which can be used as the starting point for future investigations. We show that fungi have the potential to act as electrogens or cathode catalysts, but MFCs based on bacteria–fungus interactions are especially interesting. The review presents the current state-of-the-art in the field of MFC systems exploiting fungi.

Bioelectricity production from wood hydrothermal-treatment wastewater: Enhanced power generation in MFC-fed mixed wastewaters

Electrogenic microorganisms are the heart of microbial fuel cell (MFC) systems that enable the conversion of waste into bioelectricity. Bacteria able to generate current, found in various natural and anthropogenic environments, need simple substrates such as acetate or glucose. Complex substrates are utilized by bacterial consortia made up of strains that exhibit a wide range of enzymatic and metabolic activity that determines the type of substrate they are able to degrade. The characteristics of the environment that a bacterial consortium develops in strongly affect the consortium's species composition and electrogenic potential. This study presents the first attempt to use industrial raw wastewater from the hydrothermal treatment of wood (WHTW) as a substrate and a source of bacterial consortia for MFC, so that such wastewater could simultaneously be treated and produce bioelectricity. The power generated in MFCs fed with WHTW was enhanced remarkably from 70 to 360mW/m² when municipal wastewater was introduced into the reactor. An analysis of the bacterial composition of these two types of wastewater revealed that the WHTW was dominated by the genera Thermoanaerobacterium and Paenibacillus while in the biofilm developed in the anode the main genera were Hydrogenophilus and Anaerobaculum. It has been shown for the first time that highly polluted wood industry wastewater may be effectively treated in MFC systems and the use of appropriate bacterial consortium may result in enhancing power generation accompanying wastewater treatment.

Enhancing Biochemical Methane Potential and Enrichment of Specific Electroactive Communities from Nixtamalization Wastewater using Granular Activated Carbon as a Conductive Material

Nejayote (corn step liquor) production in Mexico is approximately 1.4 × 1010 m3 per year and anaerobic digestion is an effective process to transform this waste into green energy. The biochemical methane potential (BMP) test is one of the most important tests for evaluating the biodegradability and methane production capacity of any organic waste. Previous research confirms that the addition of conductive materials significantly enhances the methane production yield. This study concludes that the addition of granular activated carbon (GAC) increases methane yield by 34% in the first instance. Furthermore, results show that methane production is increased by 54% when a GAC biofilm is developed 10 days before undertaking the BMP test. In addition, the electroactive population was 30% higher when attached to the GAC than in control reactors. Moreover, results show that electroactive communities attached to the GAC increased by 38% when a GAC biofilm is developed 10 days before undertaking the BMP test, additionally only in these reactors Geobacter was identified. GAC has two main effects in anaerobic digestion; it promotes direct interspecies electron transfer (DIET) by developing an electro-active biofilm and simultaneously it reduces redox potential from −223 mV to −470 mV. These results suggest that the addition of GAC to biodigesters, improves the anaerobic digestion performance in industrial processed food waste.