Ramandeep Singh, Srishti Chaudhary, Sukrampal Yadav et al.

STAR Protocols • 2022

Electroactive microorganisms (EAMs) are a group of microbes that can access solid extracellular electron donors or acceptors via extracellular electron transfer processes. EAMs are useful in developing various microbial electrochemical technologies. This protocol describes the use of bioelectrochemical systems (BESs) to enrich EAMs at the cathode from an extreme haloalkaline habitat. It also provides information for a detailed characterization of enriched cathodic biofilms via various cross-disciplinary techniques, including electrochemical, analytical, microscopic, and gene sequencing techniques. For complete details on the use and execution of this protocol, please refer to Chaudhary et al. (2021).

Sen Lin, Wentao Tang, Yihang Xiao et al.

Energy & Environmental Sustainability • 2025

Microbial electrochemical denitrification (MED) is emerging as a promising approach for nitrogen removal. However, its efficiency is limited by the low-rate extracellular electron transfer (EET) that occurs between microorganisms and electrodes. Due to the complex nature of electrochemical biofilms, the electron transfer mechanism in MED remains unclear. This study performs electrochemical characterization to investigate the EET mechanism of the MED biocathode. Reduction peaks observed at −0.442 ​± ​0.13 ​V and −0.218 ​± ​0.08 ​V vs. Ag/AgCl in cyclic voltammetry indicate the involvement of H 2 ase and cytochrome c in EET process, corroborated by the liner relationship between peak currents and scan rates. The decrease in charge transfer resistance of 19.2 ​% and 51.6 ​% at −0.2 ​V and −0.4 ​V, respectively, in electrochemical impedance spectroscopy fitting, indicates that cytochrome c and H 2 ase function in series to facilitate electron transfer. Elevated abundances of genes associated with H 2 ase and cytochrome c in the electroactive biofilm further support the combination of these two compounds involved in EET process. Findings in this study highlight the importance of H 2 ase and cytochrome c in MED, potentially offering alternative strategies for optimizing the MED system. • Comprehensive electrochemical characterization on denitrifying biocathode. • Direct electron transfer was identified in denitrifying biocathode. • Combination of H 2 ase and cytochrome c is the foundation of direct electron transfer. • An H 2 ase-cytochrome c pathway was proposed.

Carlos A. Ramírez-Vargas, Carlos Alberto Arias, Liang Zhang et al.

The Science of The Total Environment • 2020

Jörg Kretzschmar, Christin Koch, Jan Liebetrau et al.

Sensors and Actuators B Chemical • 2016

Microbial electrochemical sensors are an evolving technology platform based on electroactive microorganisms. Sensors based on anodic biofilms that oxidize organic substrates like acetate as living recognition element are promising for online monitoring of anaerobic digestion (AD), wastewater treatment as well as other processes. Essential for future engineering of microbial electrochemical sensors is the detailed characterization of its cross sensitivity as well as response behavior and latency. These parameters were examined on the example of a microbial electrochemical acetate sensor build in a 100 mL continuously stirred tank reactor. Furthermore, the ability of the sensor to recover after different periods (5–10 days) of shut down (i.e. open cell potential (OCP)) was studied. The sensor showed cross sensitivity towards propionate and butyrate that can be described as a baseline sum signal (0.040 ± 0.008 mA cm−2) irrespective of the applied concentration. The sensor also revealed biphasic response behavior towards dynamic changes in acetate concentration shown to be strongly dependent on prior exposure to low acetate concentrations. This behavior is discussed by means of the metabolic state of the microbial cells forming the recognition element. Furthermore, the sensor revealed full recovery of activity after three consecutive OCP periods showing that sensor shutdown is not a limiting factor. The dynamic response behavior and the cross sensitivity of the sensor are discussed as challenges for engineering of future applications.

Tuan Guo

Journal of Lightwave Technology • 2016

Surface plasmon resonance (SPR) optical fiber sensors can be used as a cost-effective and relatively simple-to-implement alternative to well established bulky prism configurations for in situ high sensitivity biochemical and electrochemical measurements. The miniaturized size and remote operation ability offer them a multitude of opportunities for single-point sensing in hard-to-reach spaces, even possibly in vivo . Grating-assisted and polarization control are two key properties of fiber-optic SPR sensors to achieve unprecedented sensitivities and limits of detection. The biosensor configuration presented here utilizes a nanoscale metal-coated tilted fiber Bragg grating (TFBG) imprinted in a commercial single-mode fiber core with no structural modifications. Such sensor provides an additional resonant mechanism of high-density narrow cladding mode spectral combs that overlap with the broader absorption of the surface plasmon for high accuracy interrogation. In this paper, we briefly review the principle, characterization and implementation of plasmonic TFBG sensors, followed by our recent developments of the “surface” and “localized” affinity studies of the biomolecules for real life problems and the electrochemical actives of electroactive biofilms for clean energy resources.

Linbin Hu, Run Liu, Yang Yang et al.

SSRN Electronic Journal • 2022

Anwar Elhadad, Seokheun Choi

The Analyst • 2022

Bioelectrochemical technologies have attracted significant scientific interest because the effective bacterial electron exchange with external electrodes can provide a sustainable solution that joins environmental remediation and energy recovery. Multispecies electroactive bacterial biofilms are catalysts that will drive the operation of bioelectrochemical devices. Unfortunately, there is a lack of understanding of key mechanisms determining their electron-generating capabilities and syntrophic relations within microbial communities in biofilms. This is because there are no universally standardized models for simple, rapid, reliable, and cost-effective fabrication and characterization of electroactive multispecies biofilms. The heterogeneous and long-term nature of biofilm formation has hampered the development of those models. This work develops novel biofabrication and analysis platforms by creating innovative, paper-based 3-D systems that accurately recapitulate the structure, function, and physiology of living multispecies biofilms. Multiple layers of paper containing bacterial cells were stacked to simulate different layered 3-D biofilm models with defined cellular compositions and microenvironments. Overall bacterial electrogenic capabilities through the biofilm structures were characterized by thoroughly monitoring collective electron flows through different external resistors. Changes in the type of species and order of stacking created biofilm modeling which allowed for the study of their electrogenic performance via variation in electron flow rate output. Furthermore, multi-laminate structures allowed for straightforward de-stacking and layer-by-layer separation for analyses of pH distribution and cellular viability. Our multi-laminate structures provide a new strategy for (i) controlling the biofilm geometry of 3-D bacterial cultures, (ii) monitoring the microbial electoral properties, and (iii) constructing an artificial biofilm layer by layer.

Alberto Hernández-Eligio, G.A. Huerta-Miranda, Sergio Martínez-Bahena et al.

Bioelectrochemistry • 2022

Linbin Hu, Run Liu, Yang Yang et al.

Chemical Engineering Journal • 2022

Gabriel Hernández‐Fernández, Beatriz Galán, Manuel Carmona et al.

Frontiers in Microbiology • 2022

A new bacterial strain has been isolated from the microbiome of solar panels and classified as Arthrobacter sp. Helios according to its 16S rDNA, positioning it in the " Arthrobacter citreus group." The isolated strain is highly tolerant to desiccation, UV radiation and to the presence of metals and metalloids, while it is motile and capable of growing in a variety of carbon sources. These characteristics, together with observation that Arthrobacter sp. Helios seems to be permanently prepared to handle the desiccation stress, make it very versatile and give it a great potential to use it as a biotechnological chassis. The new strain genome has been sequenced and its analysis revealed that it is extremely well poised to respond to environmental stresses. We have analyzed the transcriptional response of this strain to PEG6000-mediated arid stress to investigate the desiccation resistance mechanism. Most of the induced genes participate in cellular homeostasis such as ion and osmolyte transport and iron scavenging. Moreover, the greatest induction has been found in a gene cluster responsible for biogenic amine catabolism, suggesting their involvement in the desiccation resistance mechanism in this bacterium.

Nicola Lovecchio, Valentina Di Meo, Andrea Pietrelli

Bioengineering • 2023

This work presents the development of an automatic and customized measuring system employing sigma-delta analog-to-digital converters and transimpedance amplifiers for precise measurements of voltage and current signals generated by microbial fuel cells (MFCs). The system can perform multi-step discharge protocols to accurately measure the power output of MFCs, and has been calibrated to ensure high precision and low noise measurements. One of the key features of the proposed measuring system is its ability to conduct long-term measurements with variable time steps. Moreover, it is portable and cost-effective, making it ideal for use in laboratories without sophisticated bench instrumentation. The system is expandable, ranging from 2 to 12 channels by adding dual-channel boards, which allows for testing of multiple MFCs simultaneously. The functionality of the system was tested using a six-channel setup, and the results demonstrated its ability to detect and distinguish current signals from different MFCs with varying output characteristics. The power measurements obtained using the system also allow for the determination of the output resistance of the MFCs being tested. Overall, the developed measuring system is a useful tool for characterizing the performance of MFCs, and can be helpful in the optimization and development of sustainable energy production technologies.

Minmin Sun, Chengxian Wang

Heliyon • 2024

In this work, the ferrous (Fe 2+ ) and graphitic N modified graphene-based composite cathode materials (N-rGO/Fe 3 O 4 ) were developed through an in-situ reduction method, aiming to facilitate the two-electron pathway in the oxidation-reduction process. This approach generated a specific concentration of H 2 O 2 , enabling the construction of a sediment bio-electro-Fenton system using Fe 2+ released from the cathode materials. Notably, this system operates without the need for proton exchange membranes. During the cathode material preparation, the utilization of Fe 2+ as a reduction agent for graphene oxide (GO), triggered ammonia water to form graphitic N in graphene sheets. This addition enhanced the two-electron pathway, resulting in increased H 2 O 2 production. Specifically, when the Fe 2+ concentration was maintained at 0.1 mol/L, precise preparation of N-rGO/Fe 3 O 4 occurred, leading to a maximum output voltage of 0.528 V and a maximum power density of 178.17 mW/m 2 . The degradation of methyl orange (MO) reached 68.91% within a 25-h period, a phenomenon contributed to the presence of graphitic N in the graphene sheets. H 2 O 2 , a byproduct of the two-electron pathway in cathode oxidation reduction reaction, played a crucial role in constructing the bio-electro-Fenton system. This system, in conjunction with Fe 2+ released from N-rGO/Fe 3 O 4 , facilitated the complete degradation process of MO.

Aliyu Ishaq, Mohd Ismid Mohd Said, Shamila Azman et al.

Environmental Science and Pollution Research • 2023

Microbial fuel cells (MFCs) have garnered attention in bio-electrochemical leachate treatment systems. The most common forms of inorganic ammonia nitrogen are ammonium ( NH 4 + ) and free ammonia. Anaerobic digestion can be inhibited in both direct (changes in environmental conditions, such as fluctuations in temperature or pH, can indirectly hinder microbial activity and the efficiency of the digestion process) and indirect (inadequate nutrient levels, or other conditions that indirectly compromise the microbial community's ability to carry out anaerobic digestion effectively) ways by both kinds. The performance of a double-chamber MFC system-composed of an anodic chamber, a cathode chamber with fixed biofilm carriers (carbon felt material), and a Nafion 117 exchange membrane is examined in this work to determine the impact of ammonium nitrogen ( NH 4 - N ) inhibition. MFCs may hold up to 100 mL of fluid. Therefore, the bacteria involved were analysed using 16S rRNA. At room temperature, with a concentration of 800 mg L -1 of ammonium nitrogen and 13,225 mg L -1 of chemical oxygen demand (COD), the study produced a considerable power density of 234 mWm -3 . It was found that NH 4 - N concentrations above 800 mg L -1 have an inhibitory influence on power output and treatment effectiveness. Multiple routes removed the most nitrogen ( NH 4 + -N: 87.11 ± 0.7%, NO 2 - N: 93.17 ± 0.2% and TN: 75.24 ± 0.3%). Results from sequencing indicate that the anode is home to a rich microbial community, with anammox (6%), denitrifying (6.4%), and electrogenic bacteria (18.2%) making up the bulk of the population. Microbial fuel cells can efficiently and cost-effectively execute anammox, a green nitrogen removal process, in landfill leachate.

Raluca Maria Hlihor, Petronela Cozma

Processes • 2023

Industrial and agricultural progress, coupled with population expansion, has led to many questions in the scientific community over the current status of environmental pollution and natural resource scarcity [...]

Noureddine Touach, Abdellah Benzaouak, Jamil Toyir et al.

Molecules • 2023

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy, converting organic matter into electricity through microorganisms. Moreover, MFCs play an important role in remediation of environmental pollutants from wastewater with power generation. This work focuses on the evaluation of ferroelectric perovskite materials as a new class of non-precious photocatalysts for MFC cathode construction. Nanoparticles of BaTiO 3 (BT) were prepared and tested in a microbial fuel cell (MFC) as photocathode catalytic components. The catalyst phases were synthesized, identified and characterized by XRD, SEM, UV-Vis absorption spectroscopy, P-E hysteresis and dielectric measurements. The maximum absorption of BT nanoparticles was recorded at 285 nm and the energy gap (Eg) was estimated to be 3.77 eV. Photocatalytic performance of cathodes coated with BaTiO 3 was measured in a dark environment and then in the presence of a UV-visible (UV-Vis) light source, using a mixture of dairy industry and domestic wastewater as a feedstock for the MFCs. The performance of the BT cathodic component is strongly dependent on the presence of UV-Vis irradiation. The BT-based cathode functioning under UV-visible light improves the maximum power densities and the open circuit voltage (OCV) of the MFC system. The values increased from 64 mW m -2 to 498 mW m -2 and from 280 mV to 387 mV, respectively, showing that the presence of light effectively improved the photocatalytic activity of this ceramic. Furthermore, the MFCs operating under optimal conditions were able to reduce the chemical oxygen demand load in wastewater by 90% (initial COD = 2500 mg L -1 ).

Jafar Ali, Changhong Zheng, Tao Lyu et al.

Water Research • 2024

Hexavalent chromium (Cr(VI)) contamination in groundwater poses a substantial global challenge due to its high toxicity and extensive industrial applications. While the bioelectroremediation of Cr(VI) has attracted huge attention for its eco-friendly attributes, its practical application remains constrained by the hydrogeochemical conditions of groundwater (mainly pH), low electron transfer efficiency, limitations in electrocatalyst synthesis and electrode fabrication. In this study, we developed and investigated the use of N, S co-doped carbon nanofibers (CNFs) integrated on a graphite felt (GF) as a self-standing cathode (NS/CNF-GF) for the comprehensive reduction of Cr(VI) from real contaminated groundwater. The binder free cathode, prepared through electro-polymerization, was employed in a dual-chamber microbial fuel cell (MFC) for the treatment of Cr (VI)-laden real groundwater (40 mg/L) with a pH of 7.4. The electrochemical characterization of the prepared cathode revealed a distinct electroactive surface area, more wettability, facilitating enhanced adsorption and rapid electron transfer, resulting in a commendable Cr(VI) reduction rate of 0.83 mg/L/h. The MFC equipped with NS/CNF-GF demonstrated the lowest charge transfer resistance (R ct ) and generated the highest power density (155 ± 0.3 mW/m 2 ) compared to control systems. The favorable electrokinetics for modified cathode led to swift substrate consumption in the anode, releasing more electrons and protons, thereby accelerating Cr(VI) reduction to achieve the highest cathodic coulombic efficiency (C.E ca) of 80 ± 1.3 %. A similar temporal trend observed between Cr(VI) removal efficiency, COD removal efficiency, and C.E ca , underscores the effective performance of the modified electrode. The reusability of the binder free cathode, exemption from catholyte preparation and the absence of pH regulation requirements highlighted the potential scalability and applicability of our findings on a larger scale.

Jing Liu, Deli Chen, Athar Mahmood et al.

Applied Ecology and Environmental Research • 2024

This study used a Microbial Fuel Cell (MFC) to treat livestock manure water.The objective was to explore the impact of MFC on the treatment of dairy farming manure water, while generating electricity.This study offers new insights into the resource utilization of livestock manure water and its compliance with discharge standards.A single-compartment membrane-free air cathode MFC was constructed in this study.The cathode material used was a flat plate cathode.This study employed anaerobic acidification of pretreated cow manure as the inoculum and used cow manure as the substrate to assess electricity production performance.Similarly, the degradation effect of the MFC on cow manure was also investigated.The results showed that the removal rate of Chemical Oxygen Demand (COD), ammonia nitrogen, suspended solids, nitrogen, phosphorus and potassium elements from cattle manure water by MFC reached 61.24%, 87.37%, 54.30%, 61.30%, 18.30% and 3.28%, respectively, with the maximal output voltage of 60.31 mV, and the maximal power density of 1.734 mW/m 3 (1 k) within 24 h.As a result, the acidification pre-treatment microbial fuel cell effectively removed COD, ammonia nitrogen, suspended solids, and nitrogen elements.

Yu Kong, Jing Hu, Xiwu Lü et al.

Water • 2023

The tail wastewater from sewage treatment facilities usually lacks carbon sources, and its subsequent treatment for deep nitrogen removal is difficult in natural conditions. In this study, the constructed wetland (CW) was integrated with microbial fuel cell (MFC) with high-density polyethylene (HDPE) fillers as the main matrix to improve nitrogen removal under inefficient carbon source conditions. Compared with the regular MFC and CW systems, MFC-CW attained higher nitrogen removal under low-carbon source conditions. The influence of influent carbon/nitrogen ratio (C/N) on the denitrification and electricity-generation performance was explored. Although the increase of carbon source simultaneously improved chemical oxygen demand (COD), ammonia (NH4+-N), nitrate (NO3−-N) and TN removal, the power generation during the carbon source adjustment showed low relation with the variation of influent COD in the range of 40–120 mg/L. CW was more dependent on carbon sources, and the addition of bioelectrochemical systems into MFC-CW could reduce the dependence of nitrogen removal on carbon sources, especially under low carbon source conditions. These findings offer valuable insights into the potential applications of MFC-CW for tail water treatment, and its parameters for utilization in real CWs should be explored in future studies.

Oriol Casabella-Font, M Riva, José Luís Balcázar et al.

Bioresource Technology • 2024

Graphene oxide (GO) addition to anaerobic digestion has been suggested to enhance direct electron transfer. The impact of GO (0.075 g GO g -1 VS) and biologically and hydrothermally reduced GO (bio-rGO and h-rGO, respectively) on the methane production kinetics and removal of 12 pharmaceuticals was assessed in Fed-batch reactors. A decrease of 15 % in methane production was observed in the tests with GO addition compared with the control and the h-rGO. However, bio-rGO and h-rGO substantially increased the methane production rate compared to the control tests (+40 %), in the third fed-batch test. Removal of pharmaceuticals was enhanced only during the bio-reduction of GO (1st fed-batch test), whereas once the GO was bio-reduced, it followed a similar trend in the control and h-rGO tests. The addition of GO can enhance the methane production rate and, therefore, reduce the anaerobic treatment time.

Doaa Ahmed, Morsy Ahmed El‐Apasery, Shereen Ragai

Scientific Reports • 2023

Advanced and eco-friendly construction materials are being developed to reduce pollution and improve wastewater treatment efficiency. One such material is a photocatalytic nanocomposite that uses industrial wastes and natural substances to eliminate pollution. A recent study explored using an inorganic polymer composite (FM) made from a mixture of 70% fly ash and 30% metakaolin, with sodium hydroxide and sodium silicate as an alkali activator. The study evaluated the mechanical and hydration characteristics of the FM composite after 28 days in 100% humidity at room temperature. The study also examined the effect of adding 2.5 wt.% of Nano-TiO 2 to FM composite and how it affects its properties. Results indicate that adding Nano-TiO 2 to FM composite enhances its mechanical, antibacterial, and photocatalytic capabilities. Specifically, FM-TiO 2 composite showed 90% removal of reactive blue 19 dye effluent in sunlight after 90 min, making it an excellent choice for sustainable wastewater treatment. This study presents a cost-effective, eco-friendly solution to wastewater treatment, with added antimicrobial properties from Nano-TiO 2 .

Houria El Bakraoui, Miloudia Slaoui, Jamal Mabrouki et al.

Applied Sciences • 2022

In addition to producing bioenergy and molecules with high added value, microalgae have been recognized as an efficient microorganism for wastewater treatment. However, a major obstacle preventing its widespread use is the high energy cost of pretreatment, cultivation and downstream processes. Different types of wastewaters have been tested as culture mediums for microalgal biorefinery system. This review gives a summary of the most used microalgae strains for wastewater treatment, as well as information on the physical and chemical characteristics of domestic, agricultural, and industrial wastewaters. It also discusses wastewater pretreatment techniques, nutrient uptake and removal, biomass production and biomolecules productivities. There is also discussion on how microalgae remove contaminants from wastewater. Additionally, the problems and restrictions of microalgae-based wastewater treatment are explored, and recommendations are made for additional study and advancement. This literature review demonstrates that microalgae monoculture systems have proven to be beneficial as an innovative wastewater treatment technology, due to its high efficiencies in pollutant removals and biomolecule production; however, the upstream and downstream treatment pose a limit to industrialize the process. Until now, there has been no conventional design of the wastewater treatment process using microalgae in the biorefinery system, which constitutes a huge gap to assess a real life cycle assessment (LCA) and techno economic analysis (TEA).

Mustapha Omenesa Idris, Nabil Al‐Zaqri, Ismail Warad et al.

International Journal of Chemical Engineering • 2023

Microbial fuel cells (MFCs) have emerged as a viable method for bioremediation of toxic metals while also producing energy. In this paper, we examine the issue of organic substrate as a source of metabolism for microbe growth in MFC, as well as its significance for metal ion degradation in tandem with energy production. This study focused on the use of commercial sugar as an organic substrate in a single-chamber MFC. The MFC was operated for 27 days, with the highest voltage of 150 mV achieved on day 12, and toxic metal bioremediation efficiencies of 89%, 76.45%, and 89.45% for Pb2+, Cd2+, and Hg2+, respectively. Every 24 hours, the organic substrate (sugar solution) was fed into the cell. This study’s mechanism of metal ion degradation and electron transport is also thoroughly described. In addition, some future views have been highlighted.

Francisco Javier Bácame-Valenzuela, Jesús Pérez-García, Mayra Leticia Figueroa-Magallón et al.

Microorganisms • 2020

Pseudomonas aeruginosa metabolizes pyocyanin, a redox molecule related to diverse biological activities. Culture conditions for the production of pyocyanin in a defined medium were optimized using a statistical design and response surface methodology. The obtained conditions were replicated using as substrate an alkaline residual liquid of cooked maize and its by-products. The untreated effluent (raw nejayote, RN) was processed to obtain a fraction without insoluble solids (clarified fraction, CL), then separated by a 30 kDa membrane where two fractions, namely, retentate (RE) and filtered (FI), were obtained. Optimal conditions in the defined medium were 29.6 °C, 223.7 rpm and pH = 6.92, which produced 2.21 μg mL -1 of pyocyanin, and by using the wastewater, it was possible to obtain 3.25 μg mL -1 of pyocyanin in the retentate fraction at 40 h. The retentate fraction presented the highest concentration of total solids related to the maximum concentration of pyocyanin (PYO) obtained. The pyocyanin redox behavior was analyzed using electrochemical techniques. In this way, valorization of lime-cooked maize wastewater (nejayote) used as a substrate was demonstrated in the production of a value-added compound, such as pyocyanin, a redox metabolite of Pseudomonas aeruginosa NEJ01R.

Segundo Rojas-Flores, Edwin Ramirez-Asís, Jorge Gustavo Alonso Delgado-Caramutti et al.

Sustainability • 2023

Microbial fuel cells have undergone several modifications since their creation, mainly due to the different substrates that can be used as fuel for the generation of electrical energy. In this research, a deep and updated analysis of the characteristics of the literature published in the Scopus database from 1990 to 30 December 2022 has been carried out, finding 7055 documents indexed. The most used keywords are microbial fuel cells, performance, and electricity generation. From 2011 to the present, 5289 article-type documents were published; the article entitled “Microbial Fuel Cells: Methodology and Technology” by Logan B. E. et al., 2006 from Pennsylvania State University, USA in the Environmental Science and Technology journal of the ACS publisher was the most cited (4496 citations). On the other hand, in recent years, Chinese universities have begun to produce and highlight a number of documents positioning in the top ten, with six universities having the greatest presence in publications and as the country with the highest number of published and indexed documents (2773) in Scopus. Research on microbial fuel cells tends to grow, with China as a leading country on the subject, written by the author Wang X. It is observed that the new cell research trends deal with the modification and fabrication of electrodes with nanomaterials in order to improve their power and reduce costs to show their viability on a larger scale.

Yilin Dong, Jie Zhang, Qiuwen Wang et al.

Journal of Environmental Management • 2023

Irina V. Khilyas, Anatoly Sorokin, Larisa Kiseleva et al.

Scientifica • 2017

Bioelectrochemical systems such as microbial fuel cells (MFCs) are promising new technologies for efficient removal of organic compounds from industrial wastewaters, including that generated from swine farming. We inoculated two pairs of laboratory-scale MFCs with sludge granules from a beer wastewater-treating anaerobic digester (IGBS) or from sludge taken from the bottom of a tank receiving swine wastewater (SS). The SS-inoculated MFC outperformed the IGBS-inoculated MFC with regard to COD and VFA removal and electricity production. Using a metagenomic approach, we describe the microbial diversity of the MFC planktonic and anodic communities derived from the different inocula. Proteobacteria (mostly Deltaproteobacteria) became the predominant phylum in both MFC anodic communities with amplification of the electrogenic genus Geobacter being the most pronounced. Eight dominant and three minor species of Geobacter were found in both MFC anodic communities. The anodic communities of the SS-inoculated MFCs had a higher proportion of Clostridium and Bacteroides relative to those of the IGBS-inoculated MFCs, which were enriched with Pelobacter . The archaeal populations of the SS- and IGBS-inoculated MFCs were dominated by Methanosarcina barkeri and Methanothermobacter thermautotrophicus , respectively. Our results show a long-term influence of inoculum type on the performance and microbial community composition of swine wastewater-treating MFCs.

Andrew Free, Michael McDonald, Eulyn Pagaling

Advances in applied microbiology • 2018

Qiao Yang, Chao Gao, Zhenhua Wu et al.

E3S Web of Conferences • 2018

Constructed wetland (CW) is a low cost and easy operation process for wastewater treatment, while filler clogging is one of the disadvantages for this technology. Using activated carbon as the filler, a regular CW and an integration of constructed wetland with microbial fuel cell (CW-MFC) were constructed. After continuous operation of four months, specific surface area and pore size distribution of the activated carbon were analyzed. The specific surface area of the fresh activated carbon was 133.8 m 2 /g, while the filler in the CW and CW-MFC systems had specific surface area of 38.1 m 2 /g and 58.2 m 2 /g. The surface decrease of the CW-MFC filler was 21% lower than that of CW filler. Comparing with the regular CW, the filler in the CW-MFC was more clogging resistant. The alleviation of the filler clogging in CW-MFC may be caused by the micro-electric field as the function of MFC. CW-MFC is a promising microbial electrochemical technology for wastewater treatment and filler clogging resistant, there are some detailed issues deserve to be further researched.

Dileep Kumar Yeruva, Palle Ranadheer, Awanish Kumar et al.

npj Clean Water • 2019

Abstract Synthetic dyes are a major class of compounds used in the textile industry. The effluents released from these industries are carcinogenic and mutagenic in nature and pose potential threat to all life forms. Here, we designed a novel tri-phasic engineered flow through wetland system (TEWS) with three specific microenvironments (tri-phasic aquatic systems) integrated in a defined sequence to effectively treat azo dye-based textile wastewater. Tank 1 with free-floating and emergent aquatic macrophytes create anaerobic/anoxic microenvironments and facilitate reduction of the azo dye molecules. Tank 2 consists of submerged macrophytes which create an aerophilic microenvironment that direct the oxidation of carbon compounds along with nitrification. Tank 3 with free-floating plants and aquatic animals acts as filter feeder intended to remove suspended solids and colour, as well as residual carbon. The strategically designed TEWS attributes to 76%/87% of dye/chemical oxygen demand removal. The morphological toxicity test of plants and fishes illustrate the nontoxic nature of treated effluents. Thus, TEWS not only decolorizes the azo dye but also removes its toxic and mutagenic components.

Mónica López Velarde Santos, Francisco J. Rodríguez‐Valadez, Centro de Investigación y Desarrollo Tecnológico en Electroquímica et al.

Revista Internacional de Contaminación Ambiental • 2017

Vinasses are one of the main wastes generated from the mezcal industry in Mexico. Due to their high organic matter content and low pH, vinasses have negative environmental impacts if discharged without any treatment. An alternative treatment of vinasses is their use in microbial fuel cells (MFC) for organic matter removal and electricity production. In this paper, the performance of a MFC using vinasses is analyzed. Different organic matter concentrations in terms of chemical oxygen demand (COD) were tested and compared regarding power density, internal resistance, and voltage production. The results demonstrated that the highest COD tested resulted in a poor MFC performance. When using vinasses in MFC for 10 days, COD of 6000 mg/L generated 80.64 W/m 3 and when using vinasses with a COD of 17 143 mg/L, the power density dropped to 5.13 W/m 3 . Further tests of COD performance in MFC were made with 10 640 and 6760 mg/L for 68 days. It was demonstrated that a COD of 10 604 mg/L only produced 0.61 V, while a COD of 6760 mg/L reached 0.81 V. Regarding the organic matter removal, the highest COD removed (92 %) was obtained when using vinasses with a COD of 10 604 mg/L. By operating the cell with 6000 mg/L, COD removal was 83 % and with 17 143 mg/L, 49 %. To achieve a better MFC performance, the organic matter content in the electrolyte should not exceed 6000 mg/L so that the MFC does not achieve a saturated state that hinders the oxidation mechanisms and thus electricity production and COD removal.

Segundo Rojas-Flores, Santiago M. Benites, Magaly De La Cruz-Noriega et al.

Sustainability • 2023

Pollution generated by the misuse of large amounts of fruit and vegetable waste has become a major environmental and social problem for developing countries due to the absence of specialized collection centers for this type of waste. This research aims to generate electricity in an eco-friendly way using red dragon fruit (pitahaya) waste as the fuel in single-chamber microbial fuel cells on a laboratory scale using zinc and copper electrodes. It was possible to generate voltage and current peaks of 0.46 ± 0.03 V and 2.86 ± 0.07 mA, respectively, with an optimum operating pH of 4.22 ± 0.09 and an electrical conductivity of 175.86 ± 4.72 mS/cm at 8 °Brix until the tenth day of monitoring. An internal resistance of 75.58 ± 5.89 Ω was also calculated with a maximum power density of 304.33 ± 16.51 mW/cm2 at a current density of 5.06 A/cm2, while the FTIR spectra showed a decrease in the initial compounds and endings, especially at the 3331 cm−1 peaks of the O–H bonds. Finally, the yeast-like fungus Geotrichum candidum was molecularly identified (99.59%). This research will provide great opportunities for the generation of renewable energy using biomass as fuel through electronic devices with great potential to generate electricity.

Qiong Wan, Yingchun Ren, Cen Wang et al.

Polish Journal of Environmental Studies • 2021

Although there have been many studies on the process conditions of Constructed Wetlands (CW) and Microbial Fuel Cells (MFC), there are few studies on the Constructed Wetlands coupled with Microbial Fuel Cells. Currently, low power production is the main problem faced by Constructed Wetlands-Microbial Fuel Cell systems (CW-MFCs). This experiment intends to research the effects of HRT, influent COD and electrode spacing on wastewater treatment and power generation performance. In this experiment, CW-MFCs with two different electrode spacings (18 cm for reactor A and 28 cm for reactor B) were set up under continuous flow conditions. The effects of HRT, influent COD and eletrode spacing on wastewater treatment and power generation performance were explored using a single-factor controlled variable method. Experiment results showed that the extension of HRT was beneficial for contaminants removal and the power generation of the CW-MFCs, but the excessive extension was ineffective for the electricity output. The optimal HRT of the CW-MFCs was 24 h when influent COD was 500 mgl -1 . Improving influent COD within the appropriate range (500~1000 mgl -1 ) facilitated the power generation and contaminant removal performance of the CW-MFCs. The maximum output voltage and power density were obtained in reactor A when influent COD was 1000 mgl -1 and HRT was 24 h, which were 548 mV and 120 mWm -3 , respectively. Compared with reactor B, reactor with smaller electrode spacing achieved better electricity generation and contaminant degradation under the optimal condition. Its average output voltage could be improved by 5.1~46.1% and the removal rates of COD and NH 4 + -N could also be improved by 0.2~4.9 % and -0.9~13.7 %, respectively. This phenomenon indicates that there was a significant positive correlation between the number of Gram-negative bacteria and

Zhenyu Wang, Leonid Digel, Yongqiang Yuan et al.

Environmental Science and Ecotechnology • 2023

At the sediment-water interfaces, filamentous cable bacteria transport electrons from sulfide oxidation along their filaments towards oxygen or nitrate as electron acceptors. These multicellular bacteria belonging to the family Desulfobulbaceae thus form a biogeobattery that mediates redox processes between multiple elements. Cable bacteria were first reported in 2012. In the past years, cable bacteria have been found to be widely distributed across the globe. Their potential in shaping the surface water environments has been extensively studied but is not fully elucidated. In this review, the biogeochemical characteristics, conduction mechanisms, and geographical distribution of cable bacteria, as well as their ecological effects, are systematically reviewed and discussed. Novel insights for understanding and applying the role of cable bacteria in aquatic ecology are summarized.

Piao Yang, Abraham Condrich, Ling Lü et al.

DNA • 2024

Genetic engineering has revolutionized our ability to modify microorganisms for various applications in agriculture, medicine, and industry. This review examines recent advances in genetic engineering techniques for bacteria, fungi, and oomycetes, with a focus on CRISPR-Cas systems. In bacteria, CRISPR-Cas9 has enabled precise genome editing, enhancing applications in antibiotic production and metabolic engineering. For fungi, despite challenges associated with their complex cell structures, CRISPR/Cas9 has advanced the production of enzymes and secondary metabolites. In oomycetes, significant plant pathogens, modified Agrobacterium-mediated transformation, and CRISPR/Cas12a have contributed to developing disease-resistant crops. This review provides a comparative analysis of genetic engineering efficiencies across these microorganisms and addresses ethical and regulatory considerations. Future research directions include refining genetic tools to improve efficiency and expand applicability in non-model organisms. This comprehensive overview highlights the transformative potential of genetic engineering in microbiology and its implications for addressing global challenges in agriculture, medicine, and biotechnology.

Ulises Conejo-Saucedo, Alejandro Ledezma-Villanueva, Gabriela Ángeles de Paz et al.

Toxics • 2021

One of the most challenging environmental threats of the last two decades is the effects of emerging pollutants (EPs) such as pharmaceutical compounds or industrial additives. Diclofenac and bisphenol A have regularly been found in wastewater treatment plants, and in soils and water bodies because of their extensive usage and their recalcitrant nature. Due to the fact of this adversity, fungal communities play an important role in being able to safely degrade EPs. In this work, we obtained a sewage sludge sample to study both the culturable and non-culturable microorganisms through DNA extraction and massive sequencing using Illumina MiSeq techniques, with the goal of finding degraders adapted to polluted environments. Afterward, degradation experiments on diclofenac and bisphenol A were performed with the best fungal degraders. The analysis of bacterial diversity showed that Dethiosulfovibrionaceae, Comamonadaceae, and Isosphaeraceae were the most abundant families. A predominance of Ascomycota fungi in the culturable and non-culturable population was also detected. Species such as Talaromyces gossypii , Syncephalastrum monosporum , Aspergillus tabacinus , and Talaromyces verruculosus had remarkable degradation rates, up to 80% of diclofenac and bisphenol A was fully degraded. These results highlight the importance of characterizing autochthonous microorganisms and the possibility of selecting native fungal microorganisms to develop tailored biotransformation technologies for EPs.

Olga Taran

Frontiers in Chemistry • 2017

Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite), and hydroquinones-a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and interactions between quinones and pyrite might have been an early analog of these ubiquitous systems.

Kai Wang, Xiansen Ye, Huajun Zhang et al.

Scientific Reports • 2016

Knowledge about the drivers of benthic prokaryotic diversity and metabolic potential in interconnected coastal sediments at regional scales is limited. We collected surface sediments across six zones covering ~200 km in coastal northern Zhejiang, East China Sea and combined 16 S rRNA gene sequencing, community-level metabolic prediction, and sediment physicochemical measurements to investigate variations in prokaryotic diversity and metabolic gene composition with geographic distance and under local environmental conditions. Geographic distance was the most influential factor in prokaryotic β-diversity compared with major environmental drivers, including temperature, sediment texture, acid-volatile sulfide, and water depth, but a large unexplained variation in community composition suggested the potential effects of unmeasured abiotic/biotic factors and stochastic processes. Moreover, prokaryotic assemblages showed a biogeographic provincialism across the zones. The predicted metabolic gene composition similarly shifted as taxonomic composition did. Acid-volatile sulfide was strongly correlated with variation in metabolic gene composition. The enrichments in the relative abundance of sulfate-reducing bacteria and genes relevant with dissimilatory sulfate reduction were observed and predicted, respectively, in the Yushan area. These results provide insights into the relative importance of geographic distance and environmental condition in driving benthic prokaryotic diversity in coastal areas and predict specific biogeochemically-relevant genes for future studies.

Nan Jiang, Li Huang, Manhong Huang et al.

Sustainable Environment Research • 2021

Abstract In this study, thin-film composite with embedded polyester screen, cellulose triacetate with a cast nonwoven and cellulose triacetate with embedded polyester screen (CTA-ES) was examined as the intermediate membranes in osmotic microbial fuel cells (OsMFCs). The reactors were fed with actual landfill leachate and the performance was studied in two operation modes: active layer facing draw solution and active layer facing feed solution (AL-FS). The OsMFC with CTA-ES exhibited the best energy generation (maximum power density: 0.44 W m − 2 ) and pollutant removal efficiency (ammonia nitrogen: 70%, total nitrogen: 74%) in the AL-FS mode, which could be ascribed to the lowest internal resistance (237 Ω) and highest microbial richness. Pseudomonas was the highest proportion of microbial in OsMFCs. The result of this study has demonstrated the potential of OsMFCs for landfill leachate treatment.

Saúl Fernandez-Valenzuela, Francisca Chávez-Ruvalcaba, Julio Cesar Beltran-Rocha et al.

The Open Microbiology Journal • 2021

Microalgae have several applications in nutraceuticals, pharmaceuticals, cosmetics, biofuel production, and bioremediation, among other fields. Isolation and purification are extremely important for obtaining axenic cultures of microalgae from different environments and crucial for their biotechnological applications, but it is not an easy task. In view of the above, it is fundamental to know the classical and advanced techniques and examples of how scientists from around the globe have applied such methods to isolate several genera and the impact of each step on successful algal purification. This review provides a brief and simple explanation of the methodology for sampling, growth, obtention of unialgal, and posterior axenic culture, which will facilitate the development of novel microalgae-related discoveries and applications for new researchers.

S. A. Abbasi

Energy Sustainability and Society • 2018

Any manner of development can be sustainable only if the waste generated by it is not allowed to accumulate but is fully reused/recycled/recovered. Among the strategies to attain this goal have been the attempts to recover energy from municipal solid waste (MSW). About 60% of MSW is carbonaceous, consisting of materials which can either be biodegraded into fuels like methane or incinerated, thereby generating utilizable energy. MSW also contains several components—like metallic scrap and glass pieces—which can be reused or recycled, thereby achieving energy conservation. Given these attributes, MSW appears to be a potential source of energy and resources. Indeed, this belief that MSW is usable if only we try sincerely enough to do so prompts most of us to keep generating much more MSW than is warranted. But how realizable really is the energy potential of MSW? What perils loom into view when we actually set out to utilize MSW as an energy source? The present study addresses these crucially important questions. The work is based on a critical content analysis of the prior art. The generation of MSW has consistently outpaced the world’s efforts to dispose of it cleanly, and the energy (and material) recovery from MSW is easier said than done. In most instances, what is technically feasible is economically unfeasible. And what is economically feasible—such as setting the waste on fire as is often done in developing countries—is exceedingly harmful to the environment and the human health. Measures such as sanitary landfilling and incineration create as many new problems as the old ones they solve. Moreover, despite the use of these less-than-adequate technologies, a major portion of MSW generated in the world lies untreated. As the MSW output is expected to double by 2025, this situation is only set to become worse. Rising tides of E-waste would compound the problem even further. Hence, enormous stress should be put on the reduction of MSW generation by controlling wanton consumerism and wastage, rather than continuing with it in the false hope that technology will soon provide a magical solution and eliminate the problem.