The global water pollution problem is becoming increasingly crucial. One of the major contributors to water pollution is the presence of heavy metals. Heavy metals pose significant threat to both humans and all ecosystems. Various factors influence the removal of heavy metals from wastewater, including pH, temperature, natural organic matter (NOM), and ionic strength, which vary based on the chemical properties of the pollutants. More effective and modern approaches receive attention and extensively researched to substitute traditional methods such as adsorption, membrane filtration, and chemical-based separation. Among these methods, Microbial fuel cells (MFCs) are particularly intriguing. This review article focuses on MFCs and their potential applications in various fields, including clean water production. MFCs represent an innovative technology that not only generates electricity, but also demonstrates significant potential for heavy metal removal from wastewater. Cathodic chamber of MFCs effectively reduces heavy metals, while organic substrates act as carbon and electron donors in the anodic chamber. Through various mechanisms, including direct and indirect metal reduction, biofilm formation (metal sequestering), electron shuttling, and synergistic interactions among microbial communities, microorganisms exhibit remarkable efficiency in removing metals. Studies showed that dual- and single-chamber MFCs could efficiently remove a range of heavy metals, including chromium, cobalt, copper, vanadium, mercury, gold, selenium, lead, magnesium, manganese, zinc, and sodium, while simultaneously generating electricity, achieving high removal efficiencies ranging from 25% to 99.95%. This range of efficiency varies depending on the specific contaminant being targeted, the concentration of the contaminant, as well as the operating conditions such as pH and temperature. Moreover, MFCs demonstrated a wide range of power outputs, typically ranging from 0.15 W/m² to 6.58 W/m², depending on the specific configuration and conditions. These findings underscore the potential of MFCs as a sustainable and efficient approach for both wastewater treatment and energy generation.

The effect of platinum (Pt) loadings of air-cathodes in the 0-0.5 mg cm-2 range on single chamber microbial fuel cell (MFC) performance and cathode impedance was evaluated. In MFC tests, reducing benchmarking Pt loading of 0.5 mg cm-2 to 0.1-0 mg cm-2 decreased maximum power density by between 38% and 84%. The decrease in cathode open circuit potential with reduced loadings was small down to a catalyst loading of 0.03 mg cm-2, but was significant when the loading was further reduced to 0.01 or 0 mg cm-2. Impedance measurements of cathodes revealed that both charge-transfer and diffusion resistance increase with decreasing catalyst loadings on cathodes. Charge-transfer resistance of benchmarking cathode increased to a small extent when loadings were reduced to 0.1-0.03 mg cm-2. Below 0.03 mg cm-2, dramatic increase of charge-transfer resistance suggested that 0.03 mg cm-2 can be considered as the minimum Pt loading for which kinetic limitations are not of great concern and can be overcome to a large extent compared to lower loadings. In comparison to charge-transfer resistance, diffusion resistance differed more significantly between the loadings of 0.03 and 0.5 mg cm-2; and it was therefore the main component that changed the internal resistance of these cathodes.

Environmental pollution is increasing in parallel with the increase in the world population. Azo dyes are one of the most important causes of environmental pollution. Microbial electrochemical cells are biotechnological systems that generate energy from renewable sources such as electricity. This study investigated simultaneous electricity generation with the decolorization of two different azo dyes in microbial fuel cells. And also, changes in pH values, chemical oxygen demand analysis, hourly color removal rate, dye spectral scanning were investigated. Reactive Yellow 145 dye with a concentration of 10 mg/L, 20 mg/L, and 40 mg/L, and Ponceau S dye with 20 mg/L and 40 mg/L concentration were tested in microbial fuel cells, respectively. Results indicate that the maximum voltage obtained was 0.11 V at the same time as the 100% decolorization rate in Reactive Yellow 145 and was achieved at a concentration of 10 mg/L also, the maximum voltage obtained was 0.24 V at the same time as the 100% decolorization rate in Ponceau S. It was achieved at a concentration of 20 mg/L. In conclusion, microbial fuel cells appear to be promising tools in treating textile azo dye wastewaters, and computational methods can be applied to estimate the degradation mechanisms of complex organic molecules found in wastewaters.

Antidepressants accumulate in the aquatic environment due to human wastes. The possibility of microbial fuel cells (MFCs) is explored, an environmentally benign energy source to eliminate antidepressants introduced with human urine while producing electricity as an added value. Human urine containing selective serotonin reuptake inhibitors (paroxetine) and serotonin-norepinephrine reuptake inhibitors (venlafaxine, O-desmethylvenlafaxine (ODV)) are used as substrates in MFCs. Electricity production by the MFCs is monitored while simultaneous drug degradation is analyzed using liquid chromatography-tandem mass spectrometry. When the human urine samples containing drugs (10 or 50 ng drug per mL) are treated in MFCs, electricity production decreases in response to increasing drug concentrations. Upon addition of drugs-containing urine, chemical oxygen demand removal capacity of MFCs decreases from 54% to 37%. Mass spectrometry results show that drugs are degraded at a rate of 10 ng mL(-1) per hour for paroxetine, 11 ng mL(-1) per hour for venlafaxine, and 16 ng mL(-1) per hour for ODV, i.e., 94% of paroxetine, 66% of venlafaxine, and 48% of ODV is cleared in 9 h of treatment. In conclusion, MFC exhibits great potential in elimination of paroxetine, venlafaxine, and ODV from wastewater. These results can help to develop sustainable strategies to combat antidepressant pollution.

Mevastatin is one of the pollutants in wastewater that is difficult to biodegrade. In this study, the issue of mevastatin biodegradation and simultaneous electricity generation using microbial fuel cells, which is one of the current sustainable technologies, was investigated. Effects of mevastatin on the performance of single-chamber air-cathode microbial fuel cells were investigated. On average, 0.2 volts of electricity was generated in microbial fuel cells in the presence of 5.6 μM mevastatin, while mevastatin caused an important increase in coulombic efficiency, from 35±5% to 49±8. More than 90% of the mevastatin was removed in microbial fuel cells in approximately four days. In conclusion, mevastatin that causes toxicity in wastewaters could potentially be treated using microbial fuel cells. Meanwhile, mevastatin may enhance electricity generation either through improved electron transfer or suppressed methanogenesis during microbial fuel cell operations.

Abstract As an elastomer, poly(dimethylsiloxane) (PDMS) is used in various applications such as wearable technology and sealants, and is especially preferred in microelectromechanical device production due to its advantage in fabrication of microstructures. However, some of its applications such as sensor-based or electrode-based are limited due to its insulator aspect. Various conductive nanomaterials such as carbon nanotubes (CNTs), graphene, graphite, carbon black, and silver nanoparticles were incorporated into the PDMS matrix for the production of conductive nanocomposites. In this study, we produced highly conductive PDMS nanocomposites by addition of multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in a three-dimensional network. Due to the synergistic effect between CNTs and GNPs inside a polymeric matrix, we expected to obtain PDMS nanocomposites more conductive than nanocomposites with only CNTs. Additionally, we investigated the effect of sulfuric acid treatment on the electrical conductivity and surface composition of prepared PDMS/MWCNT/GNP nanocomposites. Results indicated that the electrical conductivity in sulfuric acid-treated samples was significantly higher than in untreated samples. Levels of conductivity in the range of 270.7–1074.8 S/m were achieved; the higher ones were the samples treated with sulfuric acid solution.

Polydimethylsiloxane (PDMS) is an insulator and it is commonly used in fabrication of micro-structures but there is a need of electrical conductive PDMS. Therefore, this research is mainly focused on producing PDMS nanocomposites with high electrical conductivity. Thus, we produced highly conductive PDMS nanocomposites which were filled with multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). Due to the synergistic effect between CNTs and GNPs inside a polymeric matrix, we expected to obtain more conductive nanocomposites than PDMS nanocomposite filled with only CNTs. Additionally, we investigated the effect of sulfuric acid treatment to surface composition and electrical conductivity of prepared PDMS/MWCNT/GNP nanocomposites. Results indicated that electrical conductivity of sulfuric acid-treated samples was significantly higher than untreated samples. The level of conductivity in the range of from 270.7 to 1074.9 S/m was obtained, and the higher ones are the samples treated with acid solution.

Electricity was generated directly from synthetic or human urine containing 11‑nor‑9‑carboxy‑Δ9‑tetrahydrocannabinol in air-cathode microbial fuel cells. Synthetic urine contained sodium acetate as carbon source, while actual human urine was used neat, without further supplements. Microbial fuel cells were capable of degrading more than 60% of the cannabis metabolite from human urine, while generating electricity. With synthetic urine, voltage generation reached 0.33 V, however the addition of 300 ng/mL of 11‑nor‑9‑carboxy‑Δ9‑tetrahydrocannabinol decreased the peak voltage to 0.27 V. This loss in power generation was nevertheless reversible when 11‑nor‑9‑carboxy‑Δ9‑tetrahydrocannabinol was removed from the media. Human urine containing 170 ng/mL 11‑nor‑9‑carboxy‑Δ9‑tetrahydrocannabinol produced 0.23 V of continuous electricity in the microbial fuel cells. The mechanism for degradation of cannabis metabolites in microbial fuel cells was discussed according to the results of the computational studies. In conclusion, wastewaters contaminated with a urine-based cannabis major metabolite could be treated in microbial fuel cells along with voltage generation as added-value.

Sulfuric acid hydrolysates of pinewood flour and hazelnut leaves were examined for production of electricity or hydrogen in single-chamber microbial electrochemical cells. Sucrose, which was found in certain lignocellulosic wastes such as sugar cane baggase, was tested in microbial fuel cells as a comparison to the complex structure of the lignocellulosic hydrolysates. Power density and coulombic efficiency levels reached 1995 mW/m2 and 32 ± 1%, respectively, using sucrose as carbon source. More than 88% of chemical oxygen demand was removed during this operation. The hydrolysate of pinewood flour hydrolysate generated 0.43 V of electricity at 1000 Ω external resistance. Hazelnut leaves were found to be good substrates for hydrogen gas production in MECs, with no methane production. Our results showed that lignocellulosic hydrolysates could be as efficient as the simple sugar sucrose to generate environmentally friendly electricity and hydrogen in single chamber MFCs and MECs.

Detection and partial degradation of the cocaine metabolite benzoylecgonine in synthetic and real human urine is accomplished using single-chamber air-cathode microbial fuel cells. Microbial fuel cells generate voltage in the range of 0.2-0.26 V using synthetic urine or real human urine obtained from both cocaine users and drug-free individuals. Concentrations of benzoylecgonine up to 1000 ng/mL are treated in the fuel cells, and electricity generation is decreased with respect to increasing concentrations of benzoylecgonine. Power density, current density, chemical oxygen demand removal and total carbohydrate removal data confirm that, in comparison to the synthetic urine, fuel cell performance decreases using benzoylecgonine-containing human urine as the medium. In the fuel cells, benzoylecgonine levels decrease by 14% in 24 h of incubation, as determined by mass spectrometry results. According to the computational chemistry analysis, cation form 2 of the benzoylecgonine might limit transfer of electrons from the microorganisms to anode. In conclusion, microbial fuel cell technology is shown to exhibit a potential for use as biosensors for detection and quantification of cocaine metabolite benzoylecgonine in real human urine.

Indirect detection and quantification of the neomycin sulfate antibiotic was accomplished in microbial fuel cells. Performance of the microbial fuel cells was examined on the basis of the following parameters; voltage generation, power density, current density and coulombic efficiencies. Removal of neomycin sulfate was monitored using LC-MS/MS in parallel with chemical oxygen demand and total carbohydrate removal. While neomycin sulfate was partially degraded, microbial fuel cell performance appeared to be affected and eventually inhibited by neomycin sulfate on a concentration-based fashion. In order to further examine the neomycin sulfate bio-sensing activity of the microbial fuel cell, a computational chemistry approach was used to obtain the information about the highest occupied molecular orbital-lowest unoccupied molecular orbital energy values of outer electron orbitals, their distribution, and ionization potentials (IPs). The results showed that electroactive bio-film-based MFCs can be used for sensitive detection of neomycin sulfate found in wastewaters.

BACKGROUND:Neoangiogenesis inside the atherosclerotic plaques has been linked to progression of the disease. Egfl7, a key player in adult angiogenesis, was found to be upregulated in response to vascular injury in rats. Egfl7 encodes for miR-126-3p and miR-126-5p. Specific information about miRNA-126-5p and its expression in cardiovascular disease is scarce in comparison to that of miR-126-3p.OBJECTIVES:A gene expression study was conducted to investigate the levels of Egfl7 and miRNA126-5p in human carotid artery atherosclerotic plaques aiming to gain a better understanding of the role of neoangiogenesis within plaques and the mechanisms causing atherosclerosis progression.METHODS:Egfl7 and miR-126-5p levels were studied in 14 plaque samples and 14 control samples using real-time PCR. The fold change between the carotid artery plaque tissue and control tissue was calculated using the 2(-ΔΔCT) method.RESULTS:Egfl7 was upregulated in the 11 plaque samples compared to controls, while expression levels of miR-126-5p was higher in eight of the plaque samples and lower in six as compared to control samples. Upregulation of miR-126-5p expression was correlated with high low-density lipoprotein (LDL) cholesterol (p = 0.023).CONCLUSIONS:Our findings suggest that the upregulation of Egfl7 promotes neoangiogenesis within the plaques, contributing to disease progression.

There is growing attention focused on local estrogen production in the breast tissue and its possible role in breast cancer initiation and progression. Understanding the underlying mechanisms for estrogen synthesis and the microenvironment consisting of tumor and its surrounding adipose tissue might open new avenues in breast cancer prevention, prognosis and treatment. In order to obtain insight, we compared peritumoral and tumor tissue expressions of CYP17A1 and CYP19A1 genes, which play an important role in estrogen biosynthesis. The paired tissue samples of 20 postmenopausal ER+/PR+ patients diagnosed with invasive ductal breast cancer were studied. In addition, 12 breast tissue samples obtained from premenopausal women without a history of breast cancer were also investigated as representative of normal conditions. Peritumoral adipose tissues expressed CYP19A1 approximately threefold higher than tumor itself (p = 0.001). A nonsignificant trend toward low expression of CYP17A1 was observed in peritumoral compared to tumor tissue (p = 0.687). Clinicopathological parameters and patient characteristics which are accepted as risk factors for breast cancer were also associated with individual and combined expressions of CYP17A1 and CYP19A1. This study offers that evaluation of CYP17A1 and CYP19A1 local expression levels might be useful for deciding on personalized treatment approaches and more accurate diagnosis, when evaluated together with several clinicopathological and disease risk factors. Considering the key role of these CYPs in estrogen synthesis, determining their expression levels may be useful as a postdiagnostic marker and for choosing the right treatment method in addition to the conventional approach.

Anaerobic Biotechnology, pp. 163-189 (2015) No AccessChapter 8: Microbial Fuel Cells: From Fundamentals to Wastewater Treatment ApplicationsNingshengjie Gao, Keaton Larson Lesnik, Hakan Bermek, and Hong LiuNingshengjie GaoDepartment of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331, USA, Keaton Larson LesnikDepartment of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331, USA, Hakan BermekDepartment of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331, USADepartment of Molecular Biology and Genetics, Istanbul Technical University, Maslak 34469 Istanbul, Turkey, and Hong LiuDepartment of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331, USACorresponding author.https://doi.org/10.1142/9781783267910_0008Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: Microbial fuel cells (MFCs) have continued to offer the potential to increase treatment efficiency, power generation, and energy recovery during wastewater treatment, and have garnered considerable research interest over the past 15 years. For the time being, the potential of this technology remains unfulfilled as scaling-up MFC reactors has presented a significant engineering challenge. The recent development of materials and designs that reduce fabrication costs in addition to maintaining high performance at increased reactor sizes has brought MFCs a step closer to practical application. The optimization of operating conditions has led to additional improvements in performance and has further increased the feasibility of these technologies. Herein, the fundamental concepts governing MFC performance are detailed along with highlighting developments in materials, designs, and operating conditions with the hope of promoting future scale-up efforts and a more sustainable wastewater treatment infrastructure. FiguresReferencesRelatedDetails Anaerobic BiotechnologyMetrics History PDF download

Olive mill wastewaters create significant environmental issues in olive-processing countries. One of the most hazardous groups of pollutants in these wastewaters is phenolic compounds. Here, olive mill wastewater was used as substrate and treated in single-chamber air-cathode microbial fuel cells. Olive mill wastewater yielded a maximum voltage of 381 mV on an external resistance of 1 kΩ. Notable decreases in the contents of 3,4-dihydroxybenzoic acid, tyrosol, gallic acid and p-coumaric acid were detected. Chemical oxygen demand removal rates were 65 % while removal of total phenolics by the process was lower (49 %). Microbial community analysis during the olive mill wastewater treating MFC has shown that both exoelectrogenic and phenol-degrading microorganisms have been enriched during the operation. Brevundimonas-, Sphingomonas- and Novosphingobium-related phylotypes were enriched on the anode biofilm, while Alphaproteobacteria and Bacteriodetes dominated the cathode biofilm. As one of the novel studies, it has been demonstrated that recalcitrant olive mill wastewaters could be treated and utilized for power generation in microbial fuel cells.

Five textile azo dyes, as part of an artificial mixture, were treated in single-chamber air-cathode microbial fuel cells while simultaneously utilizing acetate for electricity production. Remazol Black, Remazol Brilliant Blue, Remazol Turquoise Blue, Reactive Yellow and Reactive Red at concentrations of 40 or 80 mg l−1 were decolorized to a similar extent, at averages of 78, 95, 53, 93 and 74%, respectively, in 24 hours. During the process of decolorization, electricity generation from acetate oxidation continued. Power densities obtained in the presence of textile dyes ranged from 347 to 521 mW m−2 at the current density range of 0.071–0.086 mA cm−2. Microbial community analyses of cathode biofilm exhibited dynamic changes in abundant species following dye decolorization. Upon the addition of the first dye, a major change (63%) in microbial diversity was observed; however, subsequent addition of other dyes did not affect the community profile significantly. Actinobacteria, Aquamicrobium, Mesorhizobium, Ochrobactrum, Thauera, Paracoccus, Achromobacter and Chelatacoccus affiliated phylotypes were the major phylotypes detected. Our results demonstrate that microbial fuel cells could be a promising alternative for treatment of textile wastewaters and an active bacterial community can rapidly be established for simultaneous azo dye decolorization and sustainable electricity generation.

Wear and biological performances of a thermally oxidized Ti6Al7Nb alloy were investigated. Thermal oxidation (TO) performed at 600 °C for 60 h in air formed a 0.6 μm thick and relatively rough (having an average surface roughness of 1.1 μm) oxide layer (OL) on the surface. The OL was identified as the rutile form of TiO 2 and there was an oxygen diffusion zone (ODZ) with an average thickness of 5 μm just beneath it. The applied TO process resulted in more than ten-fold increase in wear resistance in a simulated body fluid (SBF) solution. Additionally, the biological performance was also enhanced as revealed by SBF immersion and cell culture tests.

BACKGROUND: The utilization of mixed monosaccharides commonly found in the hydrolysates of lignocellulosic biomass was evaluated for power generation in single chamber air cathode mediator-less microbial fuel cells.RESULTS: A similar voltage generation pattern was observed for all the MFCs with different monosaccharide combinations and an external resistance of 1000 Omega. However, the different monosaccharide utilization rates ranging from 212 mg L-1 h(-1) to 389 mg L-1 h(-1) indicate the presence of preferential utilization of different monosaccharides. Three volatile fatty acids (VFAs), including acetic, propionic and butyric acids were detected as the main intermediates, which were generated mainly through a fermentation process.CONCLUSION: VFAs produced from initial monosaccharides contributed to a significant portion of the total electricity generated, and the fermentation process out competed the electricity generation process when a mixed bacterial culture was used. (C) 2011 Society of Chemical Industry