Research

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14 pages, 3900 KiB

Open AccessFeature PaperArticle

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

by Rosa Anna Nastro, Fabio Flagiello, Nicandro Silvestri, Edvige Gambino, Giacomo Falcucci and Kuppam Chandrasekhar

Processes 2021, 9(11), 1941; https://doi.org/10.3390/pr9111941 - 29 Oct 2021

Cited by 11 | Viewed by 2127

Abstract

In this paper, we tested the combined use of a biochar-based material at the cathode and of Pseudomonas aeruginosa strain in a single chamber, air cathode microbial fuel cells (MFCs) fed with a mix of shredded vegetable and phosphate buffer solution (PBS) in [...] Read more.

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

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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13 pages, 1173 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Ammonium and Phosphate Recovery in a Three Chambered Microbial Electrolysis Cell: Towards Obtaining Struvite from Livestock Manure

by Míriam Cerrillo, Laura Burgos, Joan Noguerol, Victor Riau and August Bonmatí

Processes 2021, 9(11), 1916; https://doi.org/10.3390/pr9111916 - 27 Oct 2021

Cited by 6 | Viewed by 2238

Abstract

Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this [...] Read more.

Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this work, a lab-scale three-chambered microbial electrolysis cell (MEC) has been operated in continuous mode for the recovery of ammonia and phosphate from digested pig slurry in order to obtain a nutrient concentrated solution as a potential source of fertilizer (struvite). The maximum average removal efficiencies for ammonium and phosphate were 20% ± 4% and 36% ± 10%, respectively. The pH of the recovered solution was below 7, avoiding salt precipitation in the reactor. According to Visual MINTEQ software modelling, an increase of pH value to 8 outside the reactor would be enough to recover most of the potential struvite (0.21 mmol L⁻¹ d⁻¹), while the addition of up to 0.2 mM of magnesium to the nutrient recovered solution would enhance struvite production from 5.6 to 17.7 mM. The application of three-chambered MECs to the recovery of nutrients from high strength wastewater is a promising technology to avoid ammonia production through industrial processes or phosphate mineral extraction and close nutrient natural cycles. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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14 pages, 2837 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Microbial Fuel Cell as a Bioelectrochemical Sensor of Nitrite Ions

by Arnas Klevinskas, Kristina Kantminienė, Nerita Žmuidzinavičienė, Ilona Jonuškienė and Egidijus Griškonis

Processes 2021, 9(8), 1330; https://doi.org/10.3390/pr9081330 - 30 Jul 2021

Cited by 5 | Viewed by 2207

Abstract

The deteriorating environmental quality requires a rapid in situ real-time monitoring of toxic compounds in environment including water and wastewater. One of the most toxic nitrogen-containing ions is nitrite ion, therefore, it is particularly important to ensure that nitrite ions are completely absent [...] Read more.

The deteriorating environmental quality requires a rapid in situ real-time monitoring of toxic compounds in environment including water and wastewater. One of the most toxic nitrogen-containing ions is nitrite ion, therefore, it is particularly important to ensure that nitrite ions are completely absent in surface and ground waters as well as in wastewater or, at least, their concentration does not exceed permissible levels. However, no selective ion electrode, which would enable continuous measurement of nitrite ion concentration in wastewater by bioelectrochemical sensor, is available. Microbial fuel cell (MFC)-based biosensor offers a sustainable low-cost alternative to the monitoring by periodic sampling for laboratory testing. It has been determined, that at low (0.01–0.1 mg·L⁻¹) and moderate (1.0–10 mg·L⁻¹) concentration of nitrite ions in anolyte-model wastewater, the voltage drop in MFC linearly depends on the logarithm of nitrite ion concentration of proving the potential of the application of MFC-based biosensor for the quantitative monitoring of nitrite ion concentration in wastewater and other surface water. Higher concentrations (100–1000 mg·L⁻¹) of nitrite ions in anolyte-model wastewater could not be accurately quantified due to a significant drop in MFC voltage. In this case MFC can potentially serve as a bioelectrochemical early warning device for extremely high nitrite pollution. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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13 pages, 2504 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Ultra-Fast Electrochemical Sensor for Point-of-Care COVID-19 Diagnosis Using Non-Invasive Saliva Sampling

by Ashwin Ramanujam, Sharilyn Almodovar and Gerardine G. Botte

Processes 2021, 9(7), 1236; https://doi.org/10.3390/pr9071236 - 17 Jul 2021

Cited by 20 | Viewed by 4317

Abstract

Point-of-care diagnostic devices that are rapid and reliable remain as an unmet need highlighted by the coronavirus disease (COVID-19) pandemic crisis. The second/third wave of virus spread in various parts of the world combined with new evidence of re-infections and inadequate healthcare facilities [...] Read more.

Point-of-care diagnostic devices that are rapid and reliable remain as an unmet need highlighted by the coronavirus disease (COVID-19) pandemic crisis. The second/third wave of virus spread in various parts of the world combined with new evidence of re-infections and inadequate healthcare facilities demand increased testing rate to diagnose COVID-19 at its core. Although traditional molecular diagnostic tests have served this purpose, there have been shortage of reagents and other supplies at pandemic frontlines. This calls for novel alternate diagnostic processes with potential for obtaining emergency use authorization and that can be deployed in the field at the earliest opportunity. Here, we show an ultra-fast SARS-CoV-2 detection sensor for detecting coronavirus proteins in saliva within 100 milliseconds. Electrochemical oxidation of nickel hydroxide has been controlled using cyclic voltammetry and chronoamperometry techniques for successful detection of SARS-CoV-2. Test results have proven the capability of sensors to quantitatively detect the concentration of virus in blinded analyses. The detection occurs by a process similar to that of SARS-CoV-2 binding onto host cells. The sensor also shows prospects in distinguishing SARS-CoV-2 from other viruses such as HIV. More importantly, the sensor matches the detection limit of the gold standard test for diagnosing early infection. The use of saliva as a non-invasive sampling technique combined with the portability of the instrument has broadened the potential of this sensor. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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12 pages, 3353 KiB

Open AccessArticle

Simultaneous Removal of Trivalent Arsenic and Nitrate Using Microbial Fuel Cells

by Jing Guo, Jianping Cheng, Jiaquan Wang and Shuheng Hu

Processes 2021, 9(4), 673; https://doi.org/10.3390/pr9040673 - 12 Apr 2021

Cited by 5 | Viewed by 1634

Abstract

A rectangular double chamber with trivalent arsenic as the electron donor of the biological anode was constructed by microbial fuel cells (MFC), and the feasibility of the MFC simultaneous degradation of trivalent arsenic and nitrate was studied. Experimental results show that the co-matrix-coupled [...] Read more.

A rectangular double chamber with trivalent arsenic as the electron donor of the biological anode was constructed by microbial fuel cells (MFC), and the feasibility of the MFC simultaneous degradation of trivalent arsenic and nitrate was studied. Experimental results show that the co-matrix-coupled MFC reactor oxidizes trivalent arsenic in an anode chamber and degrades nitrate in the cathode chamber. The removal rate of trivalent arsenic is about 63.35%, and the degradation rate of nitrate is about 55.95% during the complete and stable operation period. MFC can continuously output electric energy, and the maximum output voltage is 388 mV. We compared and analyzed the main functional microflora of biofilm microorganisms in an anode chamber. In the long-term arsenic-polluted environment, the activity of Acinetobacter, Pseudomonas bacteria with arsenic resistance, was improved. It is inferred that a fraction of trivalent arsenic was oxidized to pentavalent arsenic by electrode-attached microorganisms. While remaining trivalent, arsenic was taken up by the suspended bacterial biomass and converted into stable arsenide. The results of this study have theoretical reference value for the expansion of the MFC application scope. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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11 pages, 1600 KiB

Open AccessFeature PaperArticle

Simplified Reactor Design for Mixed Culture-Based Electrofermentation toward Butyric Acid Production

by Paola Paiano, Giuliano Premier, Alan Guwy, Amandeep Kaur, Iain Michie, Mauro Majone and Marianna Villano

Processes 2021, 9(3), 417; https://doi.org/10.3390/pr9030417 - 25 Feb 2021

Cited by 6 | Viewed by 1719

Abstract

Mixed microbial culture (MMC) electrofermentation (EF) represents a promising tool to drive metabolic pathways toward the production of a specific compound. Here, the MMC-EF process has been exploited to obtain butyric acid in simplified membrane-less reactors operated by applying a difference of potential [...] Read more.

Mixed microbial culture (MMC) electrofermentation (EF) represents a promising tool to drive metabolic pathways toward the production of a specific compound. Here, the MMC-EF process has been exploited to obtain butyric acid in simplified membrane-less reactors operated by applying a difference of potential between two low-cost graphite electrodes. Ten values of voltage difference, from −0.60 V to −1.5 V, have been tested and compared with the experiment under open circuit potential (OCP). In all the tested conditions, an enhancement in the production rate of butyric acid (from a synthetic mixture of glucose, acetate, and ethanol) was observed, ranging from 1.3- to 2.7-fold relative to the OCP. Smaller enhancements in the production rate resulted in higher values of the calculated specific energy consumption. However, at all applied voltages, a low flow of current was detected in the one-chamber reactors, accounting for an average value of approximately −100 µA. These results hold a substantial potential with respect to the scalability of the electrofermentation technology, since they pinpoint the possibility to control MMC-based bioprocesses by simply inserting polarized electrodes into traditional fermenters. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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14 pages, 2595 KiB

Open AccessArticle

Effects of the Feeding Solution Composition on a Reductive/Oxidative Sequential Bioelectrochemical Process for Perchloroethylene Removal

by Edoardo Dell’Armi, Marco Zeppilli, Bruna Matturro, Simona Rossetti, Marco Petrangeli Papini and Mauro Majone

Processes 2021, 9(3), 405; https://doi.org/10.3390/pr9030405 - 24 Feb 2021

Cited by 12 | Viewed by 1742

Abstract

Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants due to their improper use in several industrial activities. Specialized microorganisms are able to perform the reductive dechlorination (RD) of high-chlorinated CAHs such as perchloroethylene (PCE), while the low-chlorinated ethenes such as vinyl chloride (VC) [...] Read more.

Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants due to their improper use in several industrial activities. Specialized microorganisms are able to perform the reductive dechlorination (RD) of high-chlorinated CAHs such as perchloroethylene (PCE), while the low-chlorinated ethenes such as vinyl chloride (VC) are more susceptible to oxidative mechanisms performed by aerobic dechlorinating microorganisms. Bioelectrochemical systems can be used as an effective strategy for the stimulation of both anaerobic and aerobic microbial dechlorination, i.e., a biocathode can be used as an electron donor to perform the RD, while a bioanode can provide the oxygen necessary for the aerobic dechlorination reaction. In this study, a sequential bioelectrochemical process constituted by two membrane-less microbial electrolysis cells connected in series has been, for the first time, operated with synthetic groundwater, also containing sulphate and nitrate, to simulate more realistic process conditions due to the possible establishment of competitive processes for the reducing power, with respect to previous research made with a PCE-contaminated mineral medium (with neither sulphate nor nitrate). The shift from mineral medium to synthetic groundwater showed the establishment of sulphate and nitrate reduction and caused the temporary decrease of the PCE removal efficiency from 100% to 85%. The analysis of the RD biomarkers (i.e., Dehalococcoides mccartyi 16S rRNA and tceA, bvcA, vcrA genes) confirmed the decrement of reductive dechlorination performances after the introduction of the synthetic groundwater, also characterized by a lower ionic strength and nutrients content. On the other hand, the system self-adapted the flowing current to the increased demand for the sulphate and nitrate reduction, so that reducing power was not in defect for the RD, although RD coulombic efficiency was less. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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Review

Jump to: Research

22 pages, 1812 KiB

Open AccessFeature PaperReview

Sustainable Syntheses and Sources of Nanomaterials for Microbial Fuel/Electrolysis Cell Applications: An Overview of Recent Progress

by Domenico Frattini, Gopalu Karunakaran, Eun-Bum Cho and Yongchai Kwon

Processes 2021, 9(7), 1221; https://doi.org/10.3390/pr9071221 - 15 Jul 2021

Cited by 9 | Viewed by 2333

Abstract

The use of microbial fuel cells (MFCs) is quickly spreading in the fields of bioenergy generation and wastewater treatment, as well as in the biosynthesis of valuable compounds for microbial electrolysis cells (MECs). MFCs and MECs have not been able to penetrate the [...] Read more.

The use of microbial fuel cells (MFCs) is quickly spreading in the fields of bioenergy generation and wastewater treatment, as well as in the biosynthesis of valuable compounds for microbial electrolysis cells (MECs). MFCs and MECs have not been able to penetrate the market as economic feasibility is lost when their performances are boosted by nanomaterials. The nanoparticles used to realize or decorate the components (electrodes or the membrane) have expensive processing, purification, and raw resource costs. In recent decades, many studies have approached the problem of finding green synthesis routes and cheap sources for the most common nanoparticles employed in MFCs and MECs. These nanoparticles are essentially made of carbon, noble metals, and non-noble metals, together with a few other few doping elements. In this review, the most recent findings regarding the sustainable preparation of nanoparticles, in terms of syntheses and sources, are collected, commented, and proposed for applications in MFC and MEC devices. The use of naturally occurring, recycled, and alternative raw materials for nanoparticle synthesis is showcased in detail here. Several examples of how these naturally derived or sustainable nanoparticles have been employed in microbial devices are also examined. The results demonstrate that this approach is valuable and could represent a solid alternative to the expensive use of commercial nanoparticles. Full article

(This article belongs to the Special Issue Advanced Applications, Processes, and Materials in Microbial Electrochemical Technologies)

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