Suchergebnisse

Renewable energies will represent an increasing share of the electricity supply, while flue and gasification-derived gases can be a promising CO2 feedstock with a heat load. In this study, microbial electrosynthesis of organic compounds from CO2 at high temperature was proposed as an alternative for valorising energy surplus and decarbonizing the economy. The unremitting fluctuation of renewable energy sources was assessed using two bioreactors at 50 °C, under circumstances of continuous and intermittent power supply (ON-OFF; 8-16 h), simulating an off-grid photovoltaic system. Results highlighted that maximum acetate production rate (43.27 g m−2 d−1) and columbic efficiency (98%) were achieved by working with an intermittent energy supply, while current density was reduced three times. This boosted the production of acetate per unit of electricity provided up to 138 g kWh−1 and reinforced the robustness of the technology by showing resilience to tolerate perturbations and returning to its initial state ; This work was supported by the European Union's Horizon 2020 research and innovation program under the grant agreement No 760431 (BioRECO2VER). L.R-A acknowledges the support by the Catalan Government (2018 FI-B 00347) in the European FSE program (CCI 2014ES05SFOP007). S.P is a Serra Húnter Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Academia award. LEQUIA has been recognized as consolidated research groups by the Catalan Government (2017-SGR-1552)

Electro bioremediation is gaining interest as a sustainable treatment for contaminated groundwater. Nevertheless, the investigation is still at the laboratory level, and before their implementation is necessary to overcome important drawbacks. A prevalent issue is the high groundwater hardness that generates scale deposition on electrodes that irreversibly affects the treatment effectiveness and their lifetime. For this reason, the present study evaluated a novel and sustainable approach combining electrochemical water softening as a preliminary step for electro bioremediation of nitrate-contaminated groundwater. Batch mode tests were performed at mL-scale to determine the optimum reactor configuration (single- or two-chambers) and the suitable applied cathode potential for electrochemical softening. A single-chamber reactor working at a cathode potential of −1.2 V vs. Ag/AgCl was chosen. Continuous groundwater softening under this configuration achieved a hardness removal efficiency of 64 ± 4% at a rate of 305 ± 17 mg CaCO3 m−2cathode h−1. The saturation index at the effluent of the main minerals susceptible to precipitate (aragonite, calcite, and brucite) was reduced up to 90%. Softening activity plummeted after 13 days of operation due to precipitate deposition (mostly calcite) on the cathode surface. Polarity reversal periods were considered to detach the precipitated throughout the continuous operation. Their implementation every 3–4 days increased the softening lifetime by 48%, keeping a stable hardness removal efficiency. The nitrate content of softened groundwater was removed in an electro bioremediation system at a rate of 1269 ± 30 g NO3− m−3NCC d−1 (97% nitrate removal efficiency). The energy consumption of the integrated system (1.4 kWh m−3treated) confirmed the competitiveness of the combined treatment and paves the ground for scaling up the process ; This work was funded through the European Union's Horizon 2020 project ELECTRA [no. 826244]. A.C-E. was supported by a PhD grant from the University ...

Anaerobic gas fermentation is a promising approach to transform carbon dioxide (CO2) into chemical building blocks. However, the main operational conditions to enhance the process and its selectivity are still unknown. The main objective of this study was to trigger chain elongation from a joint perspective of thermodynamic and experimental assessment. Thermodynamics revealed that acetic acid formation was the most spontaneous reaction, followed by n-caproic and n-butyric acids, while the doorway for alcohols production was bounded by the selected conditions. Best parameters combinations were applied in three 0.12L fermenters. Experimentally, n-caproic acid formation was boosted at pH 7, 37°C, Acetate:Ethanol mass ratio of 1:3 and low H2 partial pressure. Though these conditions did not match with those required to produce their main substrates, the unification of both perspectives yielded the highest n-caproic acid concentration (> 11 g L-1) so far from simple substrates, accounting for 77% of the total products ; The authors acknowledge funding from the Agency for Business Competitiveness of the Government of Catalonia (ACCIÓ; COMRDI16-1-0061) and the Spanish Ministry of Science and Innovation (RTI2018-098360-B-100 and PLEC2021-007802). LEQUIA (http://www.lequia.udg.edu/) has been recognized as a consolidated research group by the Catalan Government (2017-SGR-1552). L.R.-A. acknowledge the support by the Catalan Government (2018 FI-B 00347) in the European FSE program (CCI 2014ES05SFOP007). M.R.-C. is grateful for the support of the Spanish Government (FPU20/01362). S.P is a Serra Hunter Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Academia award

Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology. Groundwater pollution is a serious worldwide concern. Aromatic compounds, chlorinated hydrocarbons, metals and nutrients among others can be widely found in different aquifers all over the world. However, there is a lack of sustainable technologies able to treat these kinds of compounds. Microbial electro-remediation, by the means of microbial electrochemical technologies (MET), can become a promising alternative in the near future. MET can be applied for groundwater treatment in situ or ex situ, as well as for monitoring the chemical state or the microbiological activity. This document reviews the current knowledge achieved on microbial electro-remediation of groundwater and its applications ; This research was financially supported by the Spanish Government (CTQ2014-53718-R and CTM2015-71982-REDT) and the University of Girona (MPCUdG2016/137). LEQUIA has been recognized as a consolidated research group by the Catalan Government with code 2014-SGR-1168

Denitrifying bioelectrochemical systems (BES) allow safe nitrate treatment in waters with low organic carbon content without chemical requirements and at a competitive cost. However, this technology should move towards scaling-up by improving removal rate capabilities. In this study, a novel tubular design was used to evaluate whether the hydraulic retention time and the influent nitrate concentration influence the nitrate removal rate of denitrifying BES. A nitrate consumption rate of up to 849 g N mNCC−3 d−1 was reached without accumulation of nitrites at a HRT of 28 minutes. Nitrate removal activity was evaluated under different nitrate influent concentrations and under different HRTs. Results suggested preeminence of HRT on modulating the denitrifying activity. Therefore, this study presents an innovative design for nitrate removal using denitrifying BES and it demonstrates that operation at low HRTs increases the nitrate removal rate. It suggests that an appropriate approximation of scaling-up denitrifying BES would be the implementation of compact reactors connected in series operated at low HRTs ; This research was financially supported by the Spanish Government (CTQ2014-53718-R and CTM2015-71982-REDT) and the University of Girona (MPCUdG2016/137)

Denitrifying bioelectrochemical systems (BES) allow safe nitrate treatment in waters with low organic carbon content without chemical requirements and at a competitive cost. However, this technology should move towards scaling-up by improving removal rate capabilities. In this study, a novel tubular design was used to evaluate whether the hydraulic retention time and the influent nitrate concentration influence the nitrate removal rate of denitrifying BES. A nitrate consumption rate of up to 849 g N mNCC−3 d−1 was reached without accumulation of nitrites at a HRT of 28 minutes. Nitrate removal activity was evaluated under different nitrate influent concentrations and under different HRTs. Results suggested preeminence of HRT on modulating the denitrifying activity. Therefore, this study presents an innovative design for nitrate removal using denitrifying BES and it demonstrates that operation at low HRTs increases the nitrate removal rate. It suggests that an appropriate approximation of scaling-up denitrifying BES would be the implementation of compact reactors connected in series operated at low HRTs ; This research was financially supported by the Spanish Government (CTQ2014-53718-R and CTM2015-71982-REDT) and the University of Girona (MPCUdG2016/137)

Denitrifying bioelectrochemical systems (BES) allow safe nitrate treatment in waters with low organic carbon content without chemical requirements and at a competitive cost. However, this technology should move towards scaling-up by improving removal rate capabilities. In this study, a novel tubular design was used to evaluate whether the hydraulic retention time and the influent nitrate concentration influence the nitrate removal rate of denitrifying BES. A nitrate consumption rate of up to 849 g N mNCC−3 d−1 was reached without accumulation of nitrites at a HRT of 28 minutes. Nitrate removal activity was evaluated under different nitrate influent concentrations and under different HRTs. Results suggested preeminence of HRT on modulating the denitrifying activity. Therefore, this study presents an innovative design for nitrate removal using denitrifying BES and it demonstrates that operation at low HRTs increases the nitrate removal rate. It suggests that an appropriate approximation of scaling-up denitrifying BES would be the implementation of compact reactors connected in series operated at low HRTs ; This research was financially supported by the Spanish Government (CTQ2014-53718-R and CTM2015-71982-REDT) and the University of Girona (MPCUdG2016/137)

Several regions around the world present high levels of nitrate in groundwater. Due to its toxicity, nitrate must be removed before the groundwater is used as drinking-water. This study assessed how a denitrifying bioelectrochemical system could be operated to treat nitrate-polluted groundwater. It evaluated the cathode potential (from +597 to -703mV vs SHE) and the anode electron donor (acetate and water). Similar trends were found regardless of the anode electron donor. The nitrate removal rate increased from 1.05 to 5.44mgN-NO3 -LNCC -1h-1 when the cathode potential was lowered from +597 to -403mV vs SHE, where it stabilized. The nitrate reduction end-products (nitrite, nitrous oxide and dinitrogen gas) also changed with the different potentials of the cathode electrode. The World Health Organization nitrates and nitrites standards for drinking-water were reached at cathode potentials between -103 and -203mV vs SHE. The highest rate of nitrate conversion to N2 (2.59mgN-NO3 -LNCC -1h-1, 93.9%) occurred at -123mV using water as anode electron donor, with an estimated operational cost similar to conventional technologies (0.68·10-2kWhgN-NO3-removed-1). The long-term stability of proposed operation was demonstrated during 96days, and the rate of nitrate conversion to N2 even increased to 4.09mgN-NO3 -LNCC -1h-1. A carbon-free operation for a bioelectrochemical system has been developed to treat nitrate-polluted groundwater at a competitive cost ; This research was financially supported by the Spanish Government (CTQ2011-23632, CONSOLIDERCSD2007-00055) and the Catalan Government (2014-SGR-1168). Narcis Pous was supported by a project grant from the Catalan Government (2012 FI-B 00941)

Several regions around the world present high levels of nitrate in groundwater. Due to its toxicity, nitrate must be removed before the groundwater is used as drinking-water. This study assessed how a denitrifying bioelectrochemical system could be operated to treat nitrate-polluted groundwater. It evaluated the cathode potential (from +597 to -703mV vs SHE) and the anode electron donor (acetate and water). Similar trends were found regardless of the anode electron donor. The nitrate removal rate increased from 1.05 to 5.44mgN-NO3 -LNCC -1h-1 when the cathode potential was lowered from +597 to -403mV vs SHE, where it stabilized. The nitrate reduction end-products (nitrite, nitrous oxide and dinitrogen gas) also changed with the different potentials of the cathode electrode. The World Health Organization nitrates and nitrites standards for drinking-water were reached at cathode potentials between -103 and -203mV vs SHE. The highest rate of nitrate conversion to N2 (2.59mgN-NO3 -LNCC -1h-1, 93.9%) occurred at -123mV using water as anode electron donor, with an estimated operational cost similar to conventional technologies (0.68·10-2kWhgN-NO3-removed-1). The long-term stability of proposed operation was demonstrated during 96days, and the rate of nitrate conversion to N2 even increased to 4.09mgN-NO3 -LNCC -1h-1. A carbon-free operation for a bioelectrochemical system has been developed to treat nitrate-polluted groundwater at a competitive cost ; This research was financially supported by the Spanish Government (CTQ2011-23632, CONSOLIDERCSD2007-00055) and the Catalan Government (2014-SGR-1168). Narcis Pous was supported by a project grant from the Catalan Government (2012 FI-B 00941)

Several regions around the world present high levels of nitrate in groundwater. Due to its toxicity, nitrate must be removed before the groundwater is used as drinking-water. This study assessed how a denitrifying bioelectrochemical system could be operated to treat nitrate-polluted groundwater. It evaluated the cathode potential (from +597 to -703mV vs SHE) and the anode electron donor (acetate and water). Similar trends were found regardless of the anode electron donor. The nitrate removal rate increased from 1.05 to 5.44mgN-NO3 -LNCC -1h-1 when the cathode potential was lowered from +597 to -403mV vs SHE, where it stabilized. The nitrate reduction end-products (nitrite, nitrous oxide and dinitrogen gas) also changed with the different potentials of the cathode electrode. The World Health Organization nitrates and nitrites standards for drinking-water were reached at cathode potentials between -103 and -203mV vs SHE. The highest rate of nitrate conversion to N2 (2.59mgN-NO3 -LNCC -1h-1, 93.9%) occurred at -123mV using water as anode electron donor, with an estimated operational cost similar to conventional technologies (0.68·10-2kWhgN-NO3-removed-1). The long-term stability of proposed operation was demonstrated during 96days, and the rate of nitrate conversion to N2 even increased to 4.09mgN-NO3 -LNCC -1h-1. A carbon-free operation for a bioelectrochemical system has been developed to treat nitrate-polluted groundwater at a competitive cost ; This research was financially supported by the Spanish Government (CTQ2011-23632, CONSOLIDERCSD2007-00055) and the Catalan Government (2014-SGR-1168). Narcis Pous was supported by a project grant from the Catalan Government (2012 FI-B 00941)

The electric performance of a Microbial Fuel Cell (MFC) fed with swine manure, and specifically the interactions between different coexisting bacterial populations are examined in relationship to the Organic Loading Rate (OLR) and External Resistance applied to the cell. Feasibility of swine manure treatment using MFCs was already demonstrated by previous studies, however low Coulombic efficiencies were attained due to a competing methanogenic degradation occurring in the same cells. External resistance (Rext) and Organic Loading Rate have been identified as two of the key parameters affecting the balance between exoelectrogenic and methanogenic bacterial populations in a MFC system; despite this, virtually no attention had been paid to the study of OLR influence on MFCs performance. This study evaluates the performance of a MFC, treating swine manure, in this perspective, demonstrating that high OLRs (up to 11.2 kg COD m3/d) have a limiting effect on MFCs electrochemical losses, and increase absolute values of ORR (4.6 kg COD m3/d) and current production (14.9 mA). On the other hand, adoption of low OLR (as low as 0.7 kg COD m3/d) translates in an increase of both organic matter removal efficiency (52%) and Coulombic efficiency (higher than 70%). These improvements can be directly connected with the shifting balance between exoelectrogenic and methanogenic biomass populations, as confirmed by the cell's anode off-gas analysis. Hence, by adopting the appropriate design value of ORL and operating conditions, the MFC's biofilm exoelectrogenic population fraction, and thus its overall activity, can be improved considerably ; Mr. Molognoni was supported by a scholarship from the University of Pavia, and by a LLP/ERASMUS mobility grant at Lequia, Girona (Spain), where this research was in part supported by a grant from the Spanish Government (CTQ 2011-23632)

The present work assessed the alliance of microbial electrochemical technologies (METs) and fermentation in a two-step process for the electro-bioconversion of carbon dioxide (CO2) into elongated chemical building blocks. The electro bio-reduction of CO2 into acetic acid and ethanol (EtOH:HAc) at a 1-to-1 ratio is linked to a subsequent elongation step to produce C4 and C6 compounds. Key operational conditions of each step were assessed. Key parameters considered in the first step were pH, and both hydrogen and CO2 partial pressures. Concerning the second stage, selected parameters were pH, ethanol to acetate ratio, and hydrogen availability. The aim was to steer each stage's performance and to obtain higher value products. Reached EtOH:HAc proportion was over 1:1 when fed with CO2, with H2 availability and at pH around 5.3. Formed product reinforced the follow-up chain elongation processes. The fermentation step got up to C6 compounds at pH 7.0, when fed with CO2 and H2. Outcomes demonstrated that pH was a crucial factor in the overall process. The overall process carbon conversion efficiency was 38% being the CO2 transformation the limiting step. 1 kg of CO2 fed in the system resulted in the production of 0.38 kg of elongated acids (C4-C6). In other words, 1 m3 of CO2 (normal conditions) captured resulted firstly in the production of 0.90 kg CC2 and then, 0.75 kg CC4-C6 are finally acquired. The presented results pave the ground for improving the selectivity during the production of reduced commodity chemicals from CO2 and electricity ; The authors acknowledge funding from the Agency for Business Competitiveness of the Government of Catalonia (ACCIO; COMRDI16-1-0061) and the Spanish Ministry of Science (RTI2018-098360-B-I00). M.R-C. is grateful for the support of the Catalan Government (2021 FI_B 00499). R.B-G. is grateful for the FPI Grant BES-2015–074229 in the framework of the project CTQ2014-53718-R given by the Spanish Ministry of Economy and Competitiveness (MINECO). S.P. is a Serra Hunter Fellow ...

Microbial fuel cells (MFCs) technology is a bio-approach to remove organic matter and nitrogen from wastewater with concomitant production of renewable electricity. Nowadays, it exists a clear interest in moving MFCs towards application. This study aimed to demonstrate MFCs technology feasibility treating swine manure. A couple of 6-stacked MFCs presenting a total volume of 115 L were designed and operated to treat swine manure at 50 L·d-1 for more than 6 months. Two different electrodes were tested, one for each stacked MFC: Granular graphite (GG-MFC) and stainless steel mesh (SS-MFC). Organic matter was oxidised in the anode compartments, ammonium was oxidized to nitrate in an external aerated reactor, and nitrate was reduced to dinitrogen gas in the biocathodes. GG and SS-MFCs reached similar organic matter and nitrogen removal rates (1.9±0.3 kg COD m-3 d-1; 0.35±0.02 kg N m-3 d-1) with power densities between 2-4 Wm-3, being the central units the most electroactive. However, the GG-MFC performance declined overtime due to electrode crushing and the clogging of granular graphite which reduced its applicability in comparison with stainless steel. The application of stacked SS-MFC with mixed electric circuit is a feasible strategy to maintain or even improve treatment efficiencies and power densities when scaling-up MFCs ; This research was financially supported by the 532 Company Abengoa Water within the TEcoAgua project (CIEN-20091028), the Spanish 533 Government (CTQ2014-53718-R) and the Catalan Government (2014 FI-B 00093)

Microbial fuel cells (MFCs) technology is a bio-approach to remove organic matter and nitrogen from wastewater with concomitant production of renewable electricity. Nowadays, it exists a clear interest in moving MFCs towards application. This study aimed to demonstrate MFCs technology feasibility treating swine manure. A couple of 6-stacked MFCs presenting a total volume of 115 L were designed and operated to treat swine manure at 50 L·d-1 for more than 6 months. Two different electrodes were tested, one for each stacked MFC: Granular graphite (GG-MFC) and stainless steel mesh (SS-MFC). Organic matter was oxidised in the anode compartments, ammonium was oxidized to nitrate in an external aerated reactor, and nitrate was reduced to dinitrogen gas in the biocathodes. GG and SS-MFCs reached similar organic matter and nitrogen removal rates (1.9±0.3 kg COD m-3 d-1; 0.35±0.02 kg N m-3 d-1) with power densities between 2-4 Wm-3, being the central units the most electroactive. However, the GG-MFC performance declined overtime due to electrode crushing and the clogging of granular graphite which reduced its applicability in comparison with stainless steel. The application of stacked SS-MFC with mixed electric circuit is a feasible strategy to maintain or even improve treatment efficiencies and power densities when scaling-up MFCs ; This research was financially supported by the 532 Company Abengoa Water within the TEcoAgua project (CIEN-20091028), the Spanish 533 Government (CTQ2014-53718-R) and the Catalan Government (2014 FI-B 00093)

Microbial fuel cells (MFCs) technology is a bio-approach to remove organic matter and nitrogen from wastewater with concomitant production of renewable electricity. Nowadays, it exists a clear interest in moving MFCs towards application. This study aimed to demonstrate MFCs technology feasibility treating swine manure. A couple of 6-stacked MFCs presenting a total volume of 115 L were designed and operated to treat swine manure at 50 L·d-1 for more than 6 months. Two different electrodes were tested, one for each stacked MFC: Granular graphite (GG-MFC) and stainless steel mesh (SS-MFC). Organic matter was oxidised in the anode compartments, ammonium was oxidized to nitrate in an external aerated reactor, and nitrate was reduced to dinitrogen gas in the biocathodes. GG and SS-MFCs reached similar organic matter and nitrogen removal rates (1.9±0.3 kg COD m-3 d-1; 0.35±0.02 kg N m-3 d-1) with power densities between 2-4 Wm-3, being the central units the most electroactive. However, the GG-MFC performance declined overtime due to electrode crushing and the clogging of granular graphite which reduced its applicability in comparison with stainless steel. The application of stacked SS-MFC with mixed electric circuit is a feasible strategy to maintain or even improve treatment efficiencies and power densities when scaling-up MFCs ; This research was financially supported by the 532 Company Abengoa Water within the TEcoAgua project (CIEN-20091028), the Spanish 533 Government (CTQ2014-53718-R) and the Catalan Government (2014 FI-B 00093)