Abstract
SummaryThe absence of suitable terminal electron acceptors (TEA) in soil might limit the oxidative metabolism of environmental microbial populations. Bioelectroventing is a bioelectrochemical strategy that aims to enhance the biodegradation of a pollutant in the environment by overcoming the electron acceptor limitation and maximizing metabolic oxidation. Microbial electroremediating cells (MERCs) are devices that can perform such a bioelectroventing. We also report an overall profile of the 14C‐ATR metabolites and 14C mass balance in response to the different treatments. The objective of this work was to use MERC principles, under different configurations, to stimulate soil bacteria to achieve the complete biodegradation of the herbicide 14C‐atrazine (ATR) to 14 CO 2 in soils. Our study concludes that using electrodes at a positive potential [+600 mV (versus Ag/AgCl)] ATR mineralization was enhanced by 20‐fold when compared to natural attenuation in electrode‐free controls. Furthermore, ecotoxicological analysis of the soil after the bioelectroventing treatment revealed an effective clean‐up in < 20 days. The impact of electrodes on soil bioremediation suggests a promising future for this emerging environmental technology.
Highlights
Biodegradation is a major process in the complete mineralization of aromatic compounds in the environment and is considered an in situ treatment that avoids the costs derived from excavation and emission control, and is considered a cheap and clean technology (Khan et al, 2004)
In order to evaluate the degradation activity by soil microorganisms exposed to different experimental conditions, to understand the relationship between the cumulative mineralization and the increased biological activity, several cyclic voltammetries (CVs) were taken along the experimental phase to study the electron transfer interactions between soil microorganisms and anodes (Fig. 1)
These abiotic inflexion points were detected with similar intensity in the CVs performed after 7 and 20 days in both opencircuit Microbial electroremediating cells (MERCs) (Fig. 2A) and closed-circuit MERC (Fig. 2B). pol-MERC (Fig. 2D) showed an inflexion point at 0.2 V after 7 and 20 days, which appeared as well in closed-circuit MERCs but with considerably lower intensity
Summary
Biodegradation is a major process in the complete mineralization of aromatic compounds in the environment and is considered an in situ treatment that avoids the costs derived from excavation and emission control, and is considered a cheap and clean technology (Khan et al, 2004). Terminal electron acceptors limitations can be alternatively overcome using electrically conductive material like the electrodes used in microbial electroremediating cell (MERC) (Rodrigo et al, 2014). These devices allow microorganisms to transfer electrons from oxidative metabolism to a soil-buried electrode (anode). Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.
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