Microbes trading electricity in consortia of environmental and biotechnological significance

Rotaru, Amelia-Elena; Musat, Florin

doi:10.1016/j.copbio.2021.01.014

Cited by 45 publications

(24 citation statements)

References 85 publications

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“…Two fundamentally different mechanisms for this interspecies electron transfer are known. In direct interspecies electron transfer (DIET), electron-donating microbes and methanogens establish direct electrical connections that enable electron transfer from the electron-donating partner to the methanogen to support carbon dioxide reduction ( 3 – 5 ). In interspecies H 2 transfer, the electron-donating partner transfers electrons to protons, generating H 2 , which functions as a diffusive electron carrier to H 2 -utilizing methanogens, which oxidize the H 2 to harvest electrons for carbon dioxide reduction ( 6 – 8 ).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer

Holmes

Zhou

Ueki

et al. 2021

mBio

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Section: Introductionmentioning

confidence: 99%

Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer

Holmes

Zhou

Ueki

et al. 2021

mBio

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“…The main constructive difference resides in replacing the classical biofiltering material (gravel, sand) of CWs by electroconductive (EC) granular material. This EC material allows the electrons to circulate through the material, avoiding the classical electron acceptor limitation from anoxic environments, so METland R operates maximizing the electron transfer between the EC material and the electroactive bacteria (Rotaru et al, 2021). Thus, METland R is a term to denominate such general concept and it does not imply any specific operation mode.…”

Section: Introductionmentioning

confidence: 99%

Assessing METland® Design and Performance Through LCA: Techno-Environmental Study With Multifunctional Unit Perspective

Peñacoba-Antona¹,

Senán-Salinas²,

Aguirre-Sierra³

et al. 2021

Front. Microbiol.

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Conventional wastewater treatment technologies are costly and energy demanding; such issues are especially remarkable when small communities have to clean up their pollutants. In response to these requirements, a new variety of nature-based solution, so-called METland®, has been recently develop by using concepts from Microbial Electrochemical Technologies (MET) to outperform classical constructed wetland regarding wastewater treatment. Thus, the current study evaluates two operation modes (aerobic and aerobic–anoxic) of a full-scale METland®, including a Life Cycle Assessment (LCA) conducted under a Net Environmental Balance perspective. Moreover, a combined technical and environmental analysis using a Net Eutrophication Balance (NEuB) focus concluded that the downflow (aerobic) mode achieved the highest removal rates for both organic pollutant and nitrogen, and it was revealed as the most environmentally friendly design. Actually, aerobic configuration outperformed anaero/aero-mixed mode in a fold-range from 9 to 30%. LCA was indeed recalculated under diverse Functional Units (FU) to determine the influence of each FU in the impacts. Furthermore, in comparison with constructed wetland, METland® showed a remarkable increase in wastewater treatment capacity per surface area (0.6 m2/pe) without using external energy. Specifically, these results suggest that aerobic–anoxic configuration could be more environmentally friendly under specific situations where high N removal is required. The removal rates achieved demonstrated a robust adaptation to influent variations, revealing a removal average of 92% of Biology Oxygen Demand (BOD), 90% of Total Suspended Solids (TSS), 40% of total nitrogen (TN), and 30% of total phosphorus (TP). Moreover, regarding the global warming category, the overall impact was 75% lower compared to other conventional treatments like activated sludge. In conclusion, the LCA revealed that METland® appears as ideal solution for rural areas, considering the low energy requirements and high efficiency to remove organic pollutants, nitrogen, and phosphates from urban wastewater.

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“…In microbial electrochemically assisted TW systems, several EAB strains have been identified as able to grow as electroactive biofilms. These biofilms are composed mainly, but not exclusively, of microorganisms from Desulfuromonas , Pseudomonas , Shewanella , and Geobacter genera ( Aguirre-Sierra et al, 2016 ; Ramírez-Vargas et al, 2019 ; Saba et al, 2019 ; Rotaru et al, 2021 ). TWs operating under water-saturated conditions are anaerobic along almost their entire depth profile with anoxic/aerobic conditions only occurring in the uppermost section of the system at the water–air interface ( Aguirre et al, 2005 ).…”

Section: Introductionmentioning

confidence: 99%

Microbial Electrochemically Assisted Treatment Wetlands: Current Flow Density as a Performance Indicator in Real-Scale Systems in Mediterranean and Northern European Locations

et al. 2022

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A METland is an innovative treatment wetland (TW) that relies on the stimulation of electroactive bacteria (EAB) to enhance the degradation of pollutants. The METland is designed in a short-circuit mode (in the absence of an external circuit) using an electroconductive bed capable of accepting electrons from the microbial metabolism of pollutants. Although METlands are proven to be highly efficient in removing organic pollutants, the study of in situ EAB activity in full-scale systems is a challenge due to the absence of a two-electrode configuration. For the first time, four independent full-scale METland systems were tested for the removal of organic pollutants and nutrients, establishing a correlation with the electroactive response generated by the presence of EAB. The removal efficiency of the systems was enhanced by plants and mixed oxic–anoxic conditions, with an average removal of 56 g of chemical oxygen demand (COD) mbed material–3 day–1 and 2 g of total nitrogen (TN) mbed material–3 day–1 for Ørby 2 (partially saturated system). The estimated electron current density (J) provides evidence of the presence of EAB and its relationship with the removal of organic matter. The tested METland systems reached the max. values of 188.14 mA m–2 (planted system; IMDEA 1), 223.84 mA m–2 (non-planted system; IMDEA 2), 125.96 mA m–2 (full saturated system; Ørby 1), and 123.01 mA m–2 (partially saturated system; Ørby 2). These electron flow values were remarkable for systems that were not designed for energy harvesting and unequivocally show how electrons circulate even in the absence of a two-electrode system. The relation between organic load rate (OLR) at the inlet and coulombic efficiency (CE; %) showed a decreasing trend, with values ranging from 8.8 to 53% (OLR from 2.0 to 16.4 g COD m–2 day–1) for IMDEA systems and from 0.8 to 2.5% (OLR from 41.9 to 45.6 g COD m–2 day–1) for Ørby systems. This pattern denotes that the treatment of complex mixtures such as real wastewater with high and variable OLR should not necessarily result in high CE values. METland technology was validated as an innovative and efficient solution for treating wastewater for decentralized locations.

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Microbes trading electricity in consortia of environmental and biotechnological significance

Cited by 45 publications

References 85 publications

Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer

Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer

Assessing METland® Design and Performance Through LCA: Techno-Environmental Study With Multifunctional Unit Perspective

Microbial Electrochemically Assisted Treatment Wetlands: Current Flow Density as a Performance Indicator in Real-Scale Systems in Mediterranean and Northern European Locations

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