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Ceballos-Escalera A, Pous N, Bañeras L, Balaguer MD, Puig S. Advancing towards electro-bioremediation scaling-up: On-site pilot plant for successful nitrate-contaminated groundwater treatment. WATER RESEARCH 2024; 256:121618. [PMID: 38663208 DOI: 10.1016/j.watres.2024.121618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 03/26/2024] [Accepted: 04/14/2024] [Indexed: 05/12/2024]
Abstract
The potential of nitrate electro-bioremediation has been fully demonstrated at the laboratory scale, although it has not yet been fully implemented due to the challenges associated with scaling-up bioelectrochemical reactors and their on-site operation. This study describes the initial start-up and subsequent stable operation of an electro-bioremediation pilot plant for the treatment of nitrate-contaminated groundwater on-site (Navata site, Spain). The pilot plant was operated under continuous flow mode for 3 months, producing an effluent suitable for drinking water in terms of nitrates and nitrites (<50 mg NO3- L-1; 0 mg NO2- L-1). A maximum nitrate removal rate of 0.9 ± 0.1 kg NO3- m-3 d-1 (efficiency 82 ± 18 %) was achieved at a cathodic hydraulic retention time (HRTcat) of 2.0 h with a competitive energy consumption of 4.3 ± 0.4 kWh kg-1 NO3-. Under these conditions, the techno-economic analysis estimated an operational cost of 0.40 € m-3. Simultaneously, microbiological analyses revealed structural heterogeneity in the reactor, with denitrification functionality concentrated predominantly from the centre to the upper section of the reactor. The most abundant groups were Pseudomonadaceae, Rhizobiaceae, Gallionellaceae, and Xanthomonadaceae. In conclusion, this pilot plant represents a significant advancement in implementing this technology on a larger scale, validating its effectiveness in terms of nitrate removal and cost-effectiveness. Moreover, the results validate the electro-bioremediation in a real environment and encourage further investigation of its potential as a water treatment.
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Affiliation(s)
- Alba Ceballos-Escalera
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Narcís Pous
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Lluis Bañeras
- Group of Environmental Microbial Ecology, Institute of Aquatic Ecology, University of Girona, C/ Maria Aurèlia Capmany, 40, E-17003, Girona, Spain
| | - M Dolors Balaguer
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Sebastià Puig
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain.
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Ceballos-Escalera A, Pous N, Korth B, Harnisch F, Balaguer MD, Puig S. Ex-situ electrochemical characterisation of fixed-bed denitrification biocathodes: A promising strategy to improve bioelectrochemical denitrification. CHEMOSPHERE 2024; 347:140699. [PMID: 37977534 DOI: 10.1016/j.chemosphere.2023.140699] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/27/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023]
Abstract
The worldwide issue of nitrate-contaminated groundwater requires practical solutions, and electro-bioremediation offers a promising and sustainable treatment. While it has shown potential benefits, there is room for improvement in treatment rates, which is crucial for its further and effective implementation. In this field, electrochemical characterisation is a valuable tool for providing the foundation for optimising bioelectrochemical reactors, but applying it in fixed-bed reactors is challenging due to its high intrinsic electrical resistance. To overcome these challenges, this study employed the easy and swift eClamp methodology to screen different process parameters and their influence on the performance of fixed-bed denitrifying biocathodes composed of granular graphite. Granules were extracted and studied ex-situ under controlled conditions while varying key operational parameters (such as pH, temperature, and nitrate concentration). In the studied biocathode, the extracellular electron transfer associated with denitrification was identified as the primary limiting step with a formal potential of -0.225 ± 0.007 V vs. Ag/AgCl sat. KCl at pH 7 and 25 °C. By varying the nitrate concentration, it was revealed that the biocathode exhibits a strong affinity for nitrate (KMapp of 0.7 ± 0.2 mg N-NO3- L-1). The maximum denitrification rate was observed at a pH of 6 and a temperature of 35 °C. Furthermore, the findings highlight a 2e-/1H+ transfer, which holds considerable implications for the energy metabolism of bioelectrochemical denitrifiers. These compiled results provide valuable insights into the understanding of denitrifying biocathodes and enable the improvement and prediction of their performance.
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Affiliation(s)
- Alba Ceballos-Escalera
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Narcís Pous
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Benjamin Korth
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research GmbH - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research GmbH - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - M Dolors Balaguer
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain
| | - Sebastià Puig
- LEQUiA, Institute of the Environment, University of Girona, C/ Maria Aurèlia Capmany, 69, E-17003, Girona, Spain.
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Korth B, Pous N, Hönig R, Haus P, Corrêa FB, Nunes da Rocha U, Puig S, Harnisch F. Electrochemical and Microbial Dissection of Electrified Biotrickling Filters. Front Microbiol 2022; 13:869474. [PMID: 35711746 PMCID: PMC9197458 DOI: 10.3389/fmicb.2022.869474] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Electrified biotrickling filters represent sustainable microbial electrochemical technology for treating organic carbon-deficient ammonium-contaminated waters. However, information on the microbiome of the conductive granule bed cathode remains inexistent. For uncovering this black box and for identifying key process parameters, minimally invasive sampling units were introduced, allowing for the extraction of granules from different reactor layers during reactor operation. Sampled granules were analyzed using cyclic voltammetry and molecular biological tools. Two main redox sites [-288 ± 18 mV and -206 ± 21 mV vs. standard hydrogen electrode (SHE)] related to bioelectrochemical denitrification were identified, exhibiting high activity in a broad pH range (pH 6-10). A genome-centric analysis revealed a complex nitrogen food web and the presence of typical denitrifiers like Pseudomonas nitroreducens and Paracoccus versutus with none of these species being identified as electroactive microorganism so far. These are the first results to provide insights into microbial structure-function relationships within electrified biotrickling filters and underline the robustness and application potential of bioelectrochemical denitrification for environmental remediation.
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Affiliation(s)
- Benjamin Korth
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Narcís Pous
- Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, Girona, Spain
| | - Richard Hönig
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Philip Haus
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Felipe Borim Corrêa
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Ulisses Nunes da Rocha
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Sebastià Puig
- Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, Girona, Spain
| | - Falk Harnisch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
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