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Bio-electrochemical systems (BES) are a flexible biotechnological platform that can be employed to treat several types of wastewaters and recover valuable products concomitantly. Sulfate-rich wastewaters usually lack an electron donor; for this reason, implementing BES to treat the sulfate and the possibility of recovering the elemental sulfur (S0) offers a solution to this kind of wastewater. This study proposes a novel BES configuration that combines bio-electrochemical sulfate reduction in a biocathode with a sulfide–air fuel cell (FC) to recover S0. The proposed system achieved high elemental sulfur production rates (up to 386 mg S0-S L−1 d−1) with 65% of the sulfate removed recovered as S0 and a 12% lower energy consumption per kg of S0 produced (16.50 ± 0.19 kWh kg−1 S0-S) than a conventional electrochemical S0 recovery system.
Enric Blázquez; David Gabriel; Juan Baeza; Albert Guisasola; Pablo Ledezma; Stefano Freguia. Implementation of a Sulfide–Air Fuel Cell Coupled to a Sulfate-Reducing Biocathode for Elemental Sulfur Recovery. International Journal of Environmental Research and Public Health 2021, 18, 5571 .
AMA StyleEnric Blázquez, David Gabriel, Juan Baeza, Albert Guisasola, Pablo Ledezma, Stefano Freguia. Implementation of a Sulfide–Air Fuel Cell Coupled to a Sulfate-Reducing Biocathode for Elemental Sulfur Recovery. International Journal of Environmental Research and Public Health. 2021; 18 (11):5571.
Chicago/Turabian StyleEnric Blázquez; David Gabriel; Juan Baeza; Albert Guisasola; Pablo Ledezma; Stefano Freguia. 2021. "Implementation of a Sulfide–Air Fuel Cell Coupled to a Sulfate-Reducing Biocathode for Elemental Sulfur Recovery." International Journal of Environmental Research and Public Health 18, no. 11: 5571.
Low pH allows for selective oxidation of the organic fraction in urine while retaining nitrogen.
Johannes Jermakka; Stefano Freguia; Marika Kokko; Pablo Ledezma. Electrochemical system for selective oxidation of organics over ammonia in urine. Environmental Science: Water Research & Technology 2021, 7, 942 -955.
AMA StyleJohannes Jermakka, Stefano Freguia, Marika Kokko, Pablo Ledezma. Electrochemical system for selective oxidation of organics over ammonia in urine. Environmental Science: Water Research & Technology. 2021; 7 (5):942-955.
Chicago/Turabian StyleJohannes Jermakka; Stefano Freguia; Marika Kokko; Pablo Ledezma. 2021. "Electrochemical system for selective oxidation of organics over ammonia in urine." Environmental Science: Water Research & Technology 7, no. 5: 942-955.
Carboxylic acids obtained via the microbial electrochemical conversion of waste gases containing carbon dioxide (i.e., microbial electrosynthesis) can be used in lieu of nonrenewable building-block chemicals in the manufacture of a variety of products. When targeting valuable medium-chain carboxylic acids such as caproic acid, electricity-driven fermentations can be limited by the accumulation of fermentation products in the culturing media, often resulting in low volumetric productivities and titers due to direct toxicity or inhibition of the biocatalyst. In this study, we tested the effectiveness of a simple electrodialysis system in upconcentrating carboxylic acids from a model solution mimicking the effluent of a microbial electrochemical system producing short- and medium-chain carboxylic acids. Under batch extraction conditions, the electrodialysis scheme enabled the recovery of 60% (mol mol–1) of the total carboxylic acids present in the model fermentation broth. The particular arrangement of conventional monopolar ion exchange membranes and hydraulic recirculation loops allowed the progressive acidification of the extraction solution, enabling phase separation of caproic acid as an immiscible oil with 76% purity.
Paula Andrea Hernandez; Miaomiao Zhou; Igor Vassilev; Stefano Freguia; Yang Zhang; Jürg Keller; Pablo Ledezma; Bernardino Virdis. Selective Extraction of Medium-Chain Carboxylic Acids by Electrodialysis and Phase Separation. ACS Omega 2021, 6, 7841 -7850.
AMA StylePaula Andrea Hernandez, Miaomiao Zhou, Igor Vassilev, Stefano Freguia, Yang Zhang, Jürg Keller, Pablo Ledezma, Bernardino Virdis. Selective Extraction of Medium-Chain Carboxylic Acids by Electrodialysis and Phase Separation. ACS Omega. 2021; 6 (11):7841-7850.
Chicago/Turabian StylePaula Andrea Hernandez; Miaomiao Zhou; Igor Vassilev; Stefano Freguia; Yang Zhang; Jürg Keller; Pablo Ledezma; Bernardino Virdis. 2021. "Selective Extraction of Medium-Chain Carboxylic Acids by Electrodialysis and Phase Separation." ACS Omega 6, no. 11: 7841-7850.
In nature as well as in industrial microbiology, all microorganisms need to achieve redox balance. Their redox state and energy conservation highly depend on the availability of a terminal electron acceptor, for example oxygen in aerobic production processes. Under anaerobic conditions in the absence of an electron acceptor, redox balance is achieved via the production of reduced carbon-compounds (fermentation). An alternative strategy to artificially stabilize microbial redox and energy state is the use of anodic electro-fermentation (AEF). This emerging biotechnology empowers respiration under anaerobic conditions using the anode of a bioelectrochemical system as an undepletable terminal electron acceptor. Electrochemical control of redox metabolism and energy conservation via AEF can steer the carbon metabolism towards a product of interest and avoid the need for continuous and cost-inefficient supply of oxygen as well as the production of mixed reduced by-products, as is the case in aerobic production and fermentation processes, respectively. The great challenge for AEF is to establish efficient extracellular electron transfer (EET) from the microbe to the anode and link it to central carbon metabolism to enhance the synthesis of a target product. This article reviews the advantages and challenges of AEF, EET mechanisms, microbial energy gain, and discusses the rational choice of substrate-product couple as well as the choice of microbial catalyst. Besides, it discusses the potential of the industrial model-organism Bacillus subtilis as a promising candidate for AEF, which has not been yet considered for such an application. This prospective review contributes to a better understanding of how industrial microbiology can benefit from AEF and analyses key-factors required to successfully implement AEF processes. Overall, this work aims to advance the young research field especially by critically revisiting the fundamental aspects of AEF.
Igor Vassilev; Nils J.H. Averesch; Pablo Ledezma; Marika Kokko. Anodic electro-fermentation: Empowering anaerobic production processes via anodic respiration. Biotechnology Advances 2021, 48, 107728 .
AMA StyleIgor Vassilev, Nils J.H. Averesch, Pablo Ledezma, Marika Kokko. Anodic electro-fermentation: Empowering anaerobic production processes via anodic respiration. Biotechnology Advances. 2021; 48 ():107728.
Chicago/Turabian StyleIgor Vassilev; Nils J.H. Averesch; Pablo Ledezma; Marika Kokko. 2021. "Anodic electro-fermentation: Empowering anaerobic production processes via anodic respiration." Biotechnology Advances 48, no. : 107728.
This work studied the mechanisms governing the electrode processes along with the structure and impact of the passivation layer on the electro-generation of ferrate using three low-cost sacrificial iron materials: mild steel (MS), grey cast iron (GCI) and white cast iron (WCI) electrodes in highly alkaline media. Cyclic voltammetry studies showed that the mechanisms controlling the electrode reactions depend on its alloy composition as it influences the iron species formed in the passivation layer. The presence of silicon in the GCI electrode reduced the stability of the latter, significantly enhancing the ferrate electro-generation due to the persistence of γ-FeOOH in the passivation layer. The instability/dissolution of this layer contributed to a 54%-higher generation of ferrate with GCI when compared to the other electrodes, reaching a maximum titre of 37 mM of ferrate in 10 M NaOH solution with a current efficiency of 45% and the lowest specific energy consumption of 8 kWh kg−1.
M. Diaz; K. Doederer; J. Keller; M. Cataldo; B.-C. Donose; Y. Ali; P. Ledezma. Towards in situ electro-generation of ferrate for drinking water treatment: A comparison of three low-cost sacrificial iron electrodes. Journal of Electroanalytical Chemistry 2020, 880, 114897 .
AMA StyleM. Diaz, K. Doederer, J. Keller, M. Cataldo, B.-C. Donose, Y. Ali, P. Ledezma. Towards in situ electro-generation of ferrate for drinking water treatment: A comparison of three low-cost sacrificial iron electrodes. Journal of Electroanalytical Chemistry. 2020; 880 ():114897.
Chicago/Turabian StyleM. Diaz; K. Doederer; J. Keller; M. Cataldo; B.-C. Donose; Y. Ali; P. Ledezma. 2020. "Towards in situ electro-generation of ferrate for drinking water treatment: A comparison of three low-cost sacrificial iron electrodes." Journal of Electroanalytical Chemistry 880, no. : 114897.
Acid mine drainage (AMD) is a challenge for current and legacy mining operations worldwide given its potential to severely harm ecosystems and communities if inadequately managed. Treatment costs for AMD are amongst the highest in the industrial wastewater treatment sector, with limited sustainable options available to date. This work demonstrates a novel chemical-free approach to tackle AMD, whereby staged electrochemical neutralisation is employed to treat AMD and concomitantly recover metals as precipitates. This approach was guided by physico-chemical modelling and tested on real AMD from two different legacy mine sites in Australia, and compared against conventional chemical-dosing-based techniques using hydrated lime (Ca(OH)2) and sodium hydroxide (NaOH). The electrochemical treatment demonstrated the same capacity than Ca(OH)2 to neutralise AMD and remove sulfates, and both were significantly better than NaOH. However, the electrochemical approach produced less voluminous and more easily settleable sludge than Ca(OH)2. Moreover, the staged treatment approach demonstrated the potential to produce metal-rich powdered solids with a targeted composition, including rare earth elements and yttrium (REY). REY were recovered in concentrations up to 0.1% of the total solids composition, illustrating a new avenue for AMD remediation coupled with the recovery of critical metals.
Emma Thompson Brewster; Stefano Freguia; Mansour Edraki; Luke Berry; Pablo Ledezma. Staged electrochemical treatment guided by modelling allows for targeted recovery of metals and rare earth elements from acid mine drainage. Journal of Environmental Management 2020, 275, 111266 .
AMA StyleEmma Thompson Brewster, Stefano Freguia, Mansour Edraki, Luke Berry, Pablo Ledezma. Staged electrochemical treatment guided by modelling allows for targeted recovery of metals and rare earth elements from acid mine drainage. Journal of Environmental Management. 2020; 275 ():111266.
Chicago/Turabian StyleEmma Thompson Brewster; Stefano Freguia; Mansour Edraki; Luke Berry; Pablo Ledezma. 2020. "Staged electrochemical treatment guided by modelling allows for targeted recovery of metals and rare earth elements from acid mine drainage." Journal of Environmental Management 275, no. : 111266.
Nutrient recovery from source-separated human urine has been identified by many as a viable avenue towards the circular economy of nutrients. Moreover, untreated (and partially treated) urine is the main anthropogenic route of environmental discharge of nutrients, most concerning for nitrogen, whose release has exceeded the planet’s own self-healing capacity. Urine contains all key macronutrients (N, P, and K) and micronutrients (S, Ca, Mg, and trace metals) needed for plant growth and is, therefore, an excellent fertilizer. However, direct reuse is not recommended in modern society due to the presence of active organic molecules and heavy metals in urine. Many systems have been proposed and tested for nutrient recovery from urine, but none so far has reached technological maturity due to usually high power or chemical requirements or the need for advanced process controls. This work is the proof of concept for the world’s first nutrient recovery system that powers itself and does not require any chemicals or process controls. This is a variation of the previously proposed microbial electrochemical Ugold process, where a novel air cathode catalyst active in urine conditions (pH 9, high ammonia) enables in situ generation of electricity in a microbial fuel cell setup, and the simultaneous harvesting of such electricity for the electrodialytic concentration of ionic nutrients into a product stream, which is free of heavy metals. The system was able to sustain electrical current densities around 3 A m–2 for over two months while simultaneously upconcentrating N and K by a factor of 1.5–1.7.
Stefano Freguia; Maddalena Logrieco; Juliette Monetti; Pablo Ledezma; Bernardino Virdis; Seiya Tsujimura. Self-Powered Bioelectrochemical Nutrient Recovery for Fertilizer Generation from Human Urine. Sustainability 2019, 11, 5490 .
AMA StyleStefano Freguia, Maddalena Logrieco, Juliette Monetti, Pablo Ledezma, Bernardino Virdis, Seiya Tsujimura. Self-Powered Bioelectrochemical Nutrient Recovery for Fertilizer Generation from Human Urine. Sustainability. 2019; 11 (19):5490.
Chicago/Turabian StyleStefano Freguia; Maddalena Logrieco; Juliette Monetti; Pablo Ledezma; Bernardino Virdis; Seiya Tsujimura. 2019. "Self-Powered Bioelectrochemical Nutrient Recovery for Fertilizer Generation from Human Urine." Sustainability 11, no. 19: 5490.
Several industrial activities produce wastewater with high sulfate content that can cause significant environmental issues. Although bioelectrochemical systems (BESs) have recently been studied for the treatment of sulfate contained in this wastewater, the recovery of elemental sulfur with BESs is still in its beginnings. This work proposes a new reactor configuration named BES-EC, consisting of the coupling of a BES with an electrochemical cell (EC), to treat this type of wastewater and recover elemental sulfur. The reactor consisted of four electrodes: i) an abiotic anode, ii) a biocathode for the autotrophic sulfate reduction, iii) an anode of an electrochemical cell (EC) for the partial oxidation of sulfide to elemental sulfur (the biocathode and the EC anode were placed in the same chamber) and iv) an abiotic EC cathode. Several cathode potentials and sulfate loads were tested, obtaining high sulfate removal rates (up to 888 mg SO42−-S L−1 d−1 at −0.9 V vs. SHE with a specific energy consumption of 9.18 ± 0.80 kWh kg−1 SO42−-S). Exceptionally high theoretical elemental sulfur production rates (up to 498 mg S0-S L−1 d−1) were achieved with the EC controlled at a current density of 2.5 A m−2. Electron recovery around 80% was observed throughout most of the operation of the integrated system. In addition, short experiments were performed at different current densities, observing that sulfate removal did not increase proportionally to the higher applied current density. However, when the BES was controlled at 30 A m−2 and the EC at 7.5 A m−2, the proportion of elemental sulfur produced corresponded to 92.9 ± 1.9% of all sulfate removed.
Enric Blázquez; David Gabriel; Juan Antonio Baeza; Albert Guisasola; Stefano Freguia; Pablo Ledezma. Recovery of elemental sulfur with a novel integrated bioelectrochemical system with an electrochemical cell. Science of The Total Environment 2019, 677, 175 -183.
AMA StyleEnric Blázquez, David Gabriel, Juan Antonio Baeza, Albert Guisasola, Stefano Freguia, Pablo Ledezma. Recovery of elemental sulfur with a novel integrated bioelectrochemical system with an electrochemical cell. Science of The Total Environment. 2019; 677 ():175-183.
Chicago/Turabian StyleEnric Blázquez; David Gabriel; Juan Antonio Baeza; Albert Guisasola; Stefano Freguia; Pablo Ledezma. 2019. "Recovery of elemental sulfur with a novel integrated bioelectrochemical system with an electrochemical cell." Science of The Total Environment 677, no. : 175-183.
A microbial electrosynthesis cell comprising two biological cathode chambers sharing the same anode compartment is used to promote the production of C2–C4 carboxylic acids and alcohols from carbon dioxide.
Igor Vassilev; Frauke Kracke; Stefano Freguia; Jürg Keller; Jens O. Krömer; Pablo Ledezma; Bernardino Virdis. Microbial electrosynthesis system with dual biocathode arrangement for simultaneous acetogenesis, solventogenesis and carbon chain elongation. Chemical Communications 2019, 55, 4351 -4354.
AMA StyleIgor Vassilev, Frauke Kracke, Stefano Freguia, Jürg Keller, Jens O. Krömer, Pablo Ledezma, Bernardino Virdis. Microbial electrosynthesis system with dual biocathode arrangement for simultaneous acetogenesis, solventogenesis and carbon chain elongation. Chemical Communications. 2019; 55 (30):4351-4354.
Chicago/Turabian StyleIgor Vassilev; Frauke Kracke; Stefano Freguia; Jürg Keller; Jens O. Krömer; Pablo Ledezma; Bernardino Virdis. 2019. "Microbial electrosynthesis system with dual biocathode arrangement for simultaneous acetogenesis, solventogenesis and carbon chain elongation." Chemical Communications 55, no. 30: 4351-4354.
Removal and recovery of nutrients from waste streams is essential to avoid depletion of finite resources and further disruption of the nutrient cycles. Bioelectrochemical systems (BESs) are gaining interest because of their ability to recover nutrients through ion migration across membranes at a low energy demand. This work assesses the feasibility of the concept of nutrient bio-electroconcentration from domestic wastewater, which is a widely available source of nutrients in ionic form, collected via sewer networks and easily accessible at centralized wastewater treatment plants. Here, we demonstrate the limits of a three-chamber BES for the recovery of nutrients from domestic wastewater. Because of low ionic conductivity, the measured current densities did not exceed 2 A m–2, with corresponding limited nutrient ion recoveries. Moreover, in a 3D electrode, forcing higher current densities through potentiostatic control leads to higher Ohmic losses, resulting in anode potential profiles and runaway currents and potentials, with consequent unwanted water oxidation and disintegration of the graphite electrode. At the current density of 1.9 A m–2, N removal efficiency of 48.1% was obtained at the anode. However, calcium and magnesium salts precipitated on the anion-exchange membrane, putatively lowering its permselectivity and allowing for migration of cations through it. This phenomenon resulted in low N and K recovery efficiencies (12.0 and 11.5%, respectively), whereas P was not recovered because of precipitation of salts in the concentrate chamber.
Juliette Monetti; Pablo Ledezma; Bernardino Virdis; Stefano Freguia. Nutrient Recovery by Bio-Electroconcentration is Limited by Wastewater Conductivity. ACS Omega 2019, 4, 2152 -2159.
AMA StyleJuliette Monetti, Pablo Ledezma, Bernardino Virdis, Stefano Freguia. Nutrient Recovery by Bio-Electroconcentration is Limited by Wastewater Conductivity. ACS Omega. 2019; 4 (1):2152-2159.
Chicago/Turabian StyleJuliette Monetti; Pablo Ledezma; Bernardino Virdis; Stefano Freguia. 2019. "Nutrient Recovery by Bio-Electroconcentration is Limited by Wastewater Conductivity." ACS Omega 4, no. 1: 2152-2159.
Johannes Jermakka; Emma Thompson Brewster; Pablo Ledezma; Stefano Freguia. Electro-concentration for chemical-free nitrogen capture as solid ammonium bicarbonate. Separation and Purification Technology 2018, 203, 48 -55.
AMA StyleJohannes Jermakka, Emma Thompson Brewster, Pablo Ledezma, Stefano Freguia. Electro-concentration for chemical-free nitrogen capture as solid ammonium bicarbonate. Separation and Purification Technology. 2018; 203 ():48-55.
Chicago/Turabian StyleJohannes Jermakka; Emma Thompson Brewster; Pablo Ledezma; Stefano Freguia. 2018. "Electro-concentration for chemical-free nitrogen capture as solid ammonium bicarbonate." Separation and Purification Technology 203, no. : 48-55.
Microbial electrosynthesis is potentially a sustainable biotechnology for the conversion of the greenhouse gas CO2 into carboxylic acids, thus far mostly limited to acetic acid (C2). In spite of the environmental benefits of recycling CO2 emissions to counter global warming, bioelectrochemical production of acetate is not very attractive from an economic point of view. Conversely, carboxylates and corresponding alcohols with longer C content not only have a higher economical value compared to acetate, but they are also relevant platform chemicals and fuels used on a diverse array of industrial applications. Here, we report on a specific mixed reactor microbiome capable of producing a mixture of C4 and C6 carboxylic acids (isobutyric, n-butyric and n-caproic acids) and their corresponding alcohols (isobutanol, n-butanol and n-hexanol) using CO2 as the sole carbon source and reducing power provided by an electrode. Metagenomic analysis supports the hypothesis of a sequential carbon chain elongation process comprising of acetogenesis, solventogenesis and reverse β-oxidation, and that isobutyric acid derived from the isomerisation of n-butyric acid.
Igor Vassilev; Paula Andrea Hernandez; Pau Batlle-Vilanova; Stefano Freguia; Jens Olaf Krömer; Jürg Keller; Pablo Ledezma; Bernardino Virdis. Microbial Electrosynthesis of Isobutyric, Butyric, Caproic Acids, and Corresponding Alcohols from Carbon Dioxide. ACS Sustainable Chemistry & Engineering 2018, 6, 8485 -8493.
AMA StyleIgor Vassilev, Paula Andrea Hernandez, Pau Batlle-Vilanova, Stefano Freguia, Jens Olaf Krömer, Jürg Keller, Pablo Ledezma, Bernardino Virdis. Microbial Electrosynthesis of Isobutyric, Butyric, Caproic Acids, and Corresponding Alcohols from Carbon Dioxide. ACS Sustainable Chemistry & Engineering. 2018; 6 (7):8485-8493.
Chicago/Turabian StyleIgor Vassilev; Paula Andrea Hernandez; Pau Batlle-Vilanova; Stefano Freguia; Jens Olaf Krömer; Jürg Keller; Pablo Ledezma; Bernardino Virdis. 2018. "Microbial Electrosynthesis of Isobutyric, Butyric, Caproic Acids, and Corresponding Alcohols from Carbon Dioxide." ACS Sustainable Chemistry & Engineering 6, no. 7: 8485-8493.
Microbial electrochemical processes have potential to remediate acid mine drainage (AMD) wastewaters which are highly acidic and rich in sulfate and heavy metals, without the need for extensive chemical dosing.
Emma Thompson Brewster; Guillermo Pozo; Damien Batstone; Stefano Freguia; Pablo Ledezma. A modelling approach to assess the long-term stability of a novel microbial/electrochemical system for the treatment of acid mine drainage. RSC Advances 2018, 8, 18682 -18689.
AMA StyleEmma Thompson Brewster, Guillermo Pozo, Damien Batstone, Stefano Freguia, Pablo Ledezma. A modelling approach to assess the long-term stability of a novel microbial/electrochemical system for the treatment of acid mine drainage. RSC Advances. 2018; 8 (33):18682-18689.
Chicago/Turabian StyleEmma Thompson Brewster; Guillermo Pozo; Damien Batstone; Stefano Freguia; Pablo Ledezma. 2018. "A modelling approach to assess the long-term stability of a novel microbial/electrochemical system for the treatment of acid mine drainage." RSC Advances 8, no. 33: 18682-18689.
Electrochemical activity in bacteria has been observed in numerous environments and conditions. However, enrichments in circumneutral freshwater media where acetate is the main electron donor seem to invariably lead to the dominance of Geobacter spp. Here we report on an electroactive bacterial consortium which was enriched on acetate as electron donor, but in a medium which reproduces hydrolysed urine (high pH, high salinity and high free ammonia). The consortium was found to be free of Geobacter species, whereas a previously undescribed community dominated by species closely related to Pseudomonas and Desulfuromonas was established. The salient features of this community were: (i) high electroactivity, with anodic current densities up to 47.4 ± 2.0 A m-2; (ii) haloalkaliphilicity, with top performance at a medium pH of 10 and 19.5 ± 0.5 mS cm−1; and (iii) a remarkably high tolerance to free ammonia toxicity at over 2,200 mgNH3-N L−1. This community is likely to find applications in microbial electrochemical technology for nutrient recovery from source-separated urine.
Pablo Ledezma; Yang Lu; Stefano Freguia. Electroactive haloalkaliphiles exhibit exceptional tolerance to free ammonia. FEMS Microbiology Letters 2017, 365, 1 .
AMA StylePablo Ledezma, Yang Lu, Stefano Freguia. Electroactive haloalkaliphiles exhibit exceptional tolerance to free ammonia. FEMS Microbiology Letters. 2017; 365 (2):1.
Chicago/Turabian StylePablo Ledezma; Yang Lu; Stefano Freguia. 2017. "Electroactive haloalkaliphiles exhibit exceptional tolerance to free ammonia." FEMS Microbiology Letters 365, no. 2: 1.
Selective microbial retention is of paramount importance for the long-term performance of cathodic sulfate reduction in microbial electrolysis cells (MECs) due to the slow growth rate of autotrophic sulfate-reducing bacteria. In this work, we investigate the biofilm retention and current-to-sulfide conversion efficiency using carbon granules (CG) or multi-wall carbon nanotubes deposited on reticulated vitreous carbon (MWCNT-RVC) as electrode materials. For ~2months, the MECs were operated at sulfate loading rates of 21 to 309gSO4 -S/m(2)/d. Although MWCNT-RVC achieved a current density of 57±11A/m(2), greater than the 32±9A/m(2) observed using CG, both materials exhibited similar sulfate reduction rates (SRR), with MWCNT-RVC reaching 104±16gSO4 -S/m(2)/d while 110±13gSO4 -S/m(2)/d were achieved with CG. Pyrosequencing analysis of the 16S rRNA at the end of experimentation revealed a core community dominated by Desulfovibrio (28%), Methanobacterium (19%) and Desulfomicrobium (14%), on the MWCNT-RVC electrodes. While a similar Desulfovibrio relative abundance of 29% was found in CG-biofilms, Desulfomicrobium was found to be significantly less abundant (4%) and Methanobacterium practically absent (0.2%) on CG electrodes. Surprisingly, our results show that CG can achieve higher current-to-sulfide efficiencies at lower power consumption than the nano-modified three-dimensional MWCNT-RVC.
Guillermo Pozo; Yang Lu; Sebastien Pongy; Jürg Keller; Pablo Ledezma; Stefano Freguia. Selective cathodic microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing microbial electrolysis cells. Bioelectrochemistry 2017, 118, 62 -69.
AMA StyleGuillermo Pozo, Yang Lu, Sebastien Pongy, Jürg Keller, Pablo Ledezma, Stefano Freguia. Selective cathodic microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing microbial electrolysis cells. Bioelectrochemistry. 2017; 118 ():62-69.
Chicago/Turabian StyleGuillermo Pozo; Yang Lu; Sebastien Pongy; Jürg Keller; Pablo Ledezma; Stefano Freguia. 2017. "Selective cathodic microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing microbial electrolysis cells." Bioelectrochemistry 118, no. : 62-69.
The mining sector is currently under unprecedented pressure due to stringent environmental regulations. As a consequence, a permanent acid mine drainage (AMD) treatment is increasingly being regarded as a desirable target with direct benefits for the environment and the operational and economic viability of the resources sector. In this study we demonstrate that a novel bioelectrochemical system (BES) can deliver permanent treatment of acid mine drainage without chemical dosing. The technology consists of a two-cell bioelectrochemical setup to enable the removal of sulfate from the ongoing reduction-oxidation sulfur cycle to less than 550 mg L (85 ± 2% removal from a real AMD of an abandoned silver mine), thereby also reducing salinity at an electrical energy requirement of 10 ± 0.3 kWh kg of SO-S removed. In addition, the BES operation drove the removal and recovery of the main cations Al, Fe, Mg, Zn at rates of 151 ± 0 g Al m d, 179 ± 1 g Fe m d, 172 ± 1 g Mg m d and 46 ± 0 g Zn m d into a concentrate stream containing 263 ± 2 mg Al, 279 ± 2 mg Fe, 152 ± 0 mg Mg and 90 ± 0 mg Zn per gram of solid precipitated after BES fed-rate control treatment. The solid metal-sludge was twice less voluminous and 9 times more readily settleable than metal-sludge precipitated using NaOH. The continuous BES treatment also demonstrated the concomitant precipitation of rare earth elements together with yttrium (REY), with up to 498 ± 70 μg Y, 166 ± 27 μg Nd, 155 ± 14 μg Gd per gram of solid, among other high-value metals. The high-REY precipitates could be used to offset the treatment costs.
Guillermo Pozo; Sebastien Pongy; Jürg Keller; Pablo Ledezma; Stefano Freguia. A novel bioelectrochemical system for chemical-free permanent treatment of acid mine drainage. Water Research 2017, 126, 411 -420.
AMA StyleGuillermo Pozo, Sebastien Pongy, Jürg Keller, Pablo Ledezma, Stefano Freguia. A novel bioelectrochemical system for chemical-free permanent treatment of acid mine drainage. Water Research. 2017; 126 ():411-420.
Chicago/Turabian StyleGuillermo Pozo; Sebastien Pongy; Jürg Keller; Pablo Ledezma; Stefano Freguia. 2017. "A novel bioelectrochemical system for chemical-free permanent treatment of acid mine drainage." Water Research 126, no. : 411-420.
The following sections are included:
Stefano Freguia; Kun Guo; Pablo Ledezma. Fundamentals of Microbial Electrochemical Systems. Functional Electrodes for Enzymatic and Microbial Electrochemical Systems 2017, 51 -75.
AMA StyleStefano Freguia, Kun Guo, Pablo Ledezma. Fundamentals of Microbial Electrochemical Systems. Functional Electrodes for Enzymatic and Microbial Electrochemical Systems. 2017; ():51-75.
Chicago/Turabian StyleStefano Freguia; Kun Guo; Pablo Ledezma. 2017. "Fundamentals of Microbial Electrochemical Systems." Functional Electrodes for Enzymatic and Microbial Electrochemical Systems , no. : 51-75.
This letter presents the proof of concept of a novel bio-electroconcentration system (BEC), a hybrid microbial electrolysis/electrodialysis cell specifically designed to recover nitrogen (as ammonia NH4-N), phosphorus (as phosphate PO4-P), and potassium (as K+) from urine. Using a synthetic urine medium, the BECs could reach high current densities of up to 37.6 A m–2 at Ewe values of 0.0 versus the standard hydrogen electrode (SHE) and 50 A m–2 at 0.2 V versus SHE, which in turn drove the removal and recovery of N, P, and K at rates of 7.18 kg of NH4-N m–3 day–1, 0.52 kg of PO4-P m–3 day–1, and 1.62 kg of K+ m–3 day–1 into a concentrate stream (containing 1.87 M NH4-N, 0.29 M PO4-P, and 0.18 M K+). Finally, this communication demonstrates the recovery of a nitrogen-rich solid from the synthetic urine (in the form of pure NH4HCO3 crystals with 17% N content) without any chemical additions via the flash-cooling of the produced nutrient-rich concentrate to 4 °C. These two new products may help facilitate the reuse of urine nutrients in the fertilizer or protein production industries of the future.
Pablo Ledezma; Johannes Jermakka; Jurg Keller; Stefano Freguia. Recovering Nitrogen as a Solid without Chemical Dosing: Bio-Electroconcentration for Recovery of Nutrients from Urine. Environmental Science & Technology Letters 2017, 4, 119 -124.
AMA StylePablo Ledezma, Johannes Jermakka, Jurg Keller, Stefano Freguia. Recovering Nitrogen as a Solid without Chemical Dosing: Bio-Electroconcentration for Recovery of Nutrients from Urine. Environmental Science & Technology Letters. 2017; 4 (3):119-124.
Chicago/Turabian StylePablo Ledezma; Johannes Jermakka; Jurg Keller; Stefano Freguia. 2017. "Recovering Nitrogen as a Solid without Chemical Dosing: Bio-Electroconcentration for Recovery of Nutrients from Urine." Environmental Science & Technology Letters 4, no. 3: 119-124.
Guillermo Pozo; Ludovic Jourdin; Yang Lu; Jürg Keller; Pablo Ledezma; Stefano Freguia. Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction. Electrochimica Acta 2016, 213, 66 -74.
AMA StyleGuillermo Pozo, Ludovic Jourdin, Yang Lu, Jürg Keller, Pablo Ledezma, Stefano Freguia. Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction. Electrochimica Acta. 2016; 213 ():66-74.
Chicago/Turabian StyleGuillermo Pozo; Ludovic Jourdin; Yang Lu; Jürg Keller; Pablo Ledezma; Stefano Freguia. 2016. "Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction." Electrochimica Acta 213, no. : 66-74.
Correction for ‘Methanobacterium enables high rate electricity-driven autotrophic sulfate reduction’ by Guillermo Pozo et al., RSC Adv., 2015, 5, 89368–89374.
Guillermo Pozo; Ludovic Jourdin; Yang Lu; Pablo Ledezma; Jurg Keller; Stefano Freguia. Correction: Methanobacterium enables high rate electricity-driven autotrophic sulfate reduction. RSC Advances 2015, 5, 91821 -91821.
AMA StyleGuillermo Pozo, Ludovic Jourdin, Yang Lu, Pablo Ledezma, Jurg Keller, Stefano Freguia. Correction: Methanobacterium enables high rate electricity-driven autotrophic sulfate reduction. RSC Advances. 2015; 5 (111):91821-91821.
Chicago/Turabian StyleGuillermo Pozo; Ludovic Jourdin; Yang Lu; Pablo Ledezma; Jurg Keller; Stefano Freguia. 2015. "Correction: Methanobacterium enables high rate electricity-driven autotrophic sulfate reduction." RSC Advances 5, no. 111: 91821-91821.