Hydrophobic organic pollutants in aqueous environments are challenging to biodegrade due to limited contact between microorganisms, the pollutants and the electron acceptor, particularly under anaerobic or anoxic conditions. Here, we propose a novel strategy that uses inexpensive, dual-function elemental sulfur (S) to enhance biodegradation. Using petroleum hydrocarbons as the target pollutants, we demonstrated that hydrophobic and nonpolar S° can concentrate hydrocarbons while simultaneously serving as an electron acceptor to enrich hydrocarbon-degrading bacteria.
View Article and Find Full Text PDFMercury nanoparticles are abundant in natural environments. Yet, understanding their contribution to global biogeochemical cycling of mercury remains elusive. Here, we show that microbial transformation of nanoparticulate divalent mercury can be an important source of elemental and methylmercury.
View Article and Find Full Text PDFBioresour Technol
August 2024
Microbial electrochemical sensor (MES) using electroactive biofilm (EAB) as the sensing element represents a broad-spectrum technology for early warning of biotoxicity of water samples. However, its commercial application is impeded by limited sensitivity and repeatability. Here, we proposed a layered standardized EAB (SEAB) with enriched Geobacter anodireducens SD-1 in the inner layer and self-matched outer layer.
View Article and Find Full Text PDFThe use of microbial electrochemical sensors, with electroactive biofilms (EABs) as sensing elements, is a promising strategy to timely measure the biochemical oxygen demand (BOD) of wastewater. However, accumulation of Coulombic yield over a complete degradation cycle is time-consuming. Therefore, understanding the correlation between current output and EAB metabolism is urgently needed.
View Article and Find Full Text PDFBioreduction of nitrate to value-added ammonium is a potentially sustainable strategy to recycle nutrients from wastewater. Here, we have proven the feasibility of the reduction of autotrophic nitrate to ammonium with electrons extracted from Fe(0). Using a -dominated anodic biofilm as an inoculum, we achieved nitrate-to-ammonium efficiency up to 90 ± 3% with a nitrate reduction rate of 35 ± 1.
View Article and Find Full Text PDFJ Hazard Mater
September 2023
The proliferation of emerging contaminants (ECs) in the environment poses a major threat to the safety of reuse water. However, many ECs exist for which no corresponding control standards have been established. Here, we used polarity reversal to construct a biocathode sensor capable of early warning of ECs biotoxicity in aerobic reuse water with low organic concentrations.
View Article and Find Full Text PDFMicrobial electrochemical sensors are promising to monitor bioavailable organics in real environments, but their application is restricted by the unpredictable performance of the electroactive biofilm (EAB), which is randomly acclimated from environmental microflora. With a long-term stable EAB as a template, we successfully designed EAB (DEAB) by the sequential growth of and automatched microbes, achieving a reproducible high current than those naturally acclimated from wastewater (NEAB). Pre-inoculation of planktonic aerobes as oxygen bioscavengers was necessary to ensure the colonization of in the inner layer, and the abundant (50%) in DEAB guaranteed 4 times higher current density with a 15-fold smaller variation among 20 replicates than those of NEAB.
View Article and Find Full Text PDFSci Total Environ
July 2023
The inevitable deposition of S on the electroactive biofilm (EAB) via anodic sulfide oxidation affects the stability of bioelectrochemical systems (BESs) when an accidental discharge of sulfide occurred, leading to the inhibition of electroacitivity, because the potential of anode (e.g., 0 V versus Ag/AgCl) is ~500 mV more positive than the redox potential of S/S.
View Article and Find Full Text PDFBiochemical oxygen demand (BOD) is a key indicator of water quality. However, there is still no technique to directly measure BOD at low concentrations in oxygen-rich environments. Here, we propose a new scheme using facultative electrotrophs as the sensing element, and confirmed aerobic Acinetobacter venetianus RAG-1 immobilized on electrode was able to measure BOD via the switchover between electrotrophic and heterotrophic respirations.
View Article and Find Full Text PDFJ Hazard Mater
February 2023
Organohalide respiring bacteria (OHRB) are the mainstay for bioremediation of organohalide contaminated sites. Enrichment screening of OHRB is prerequisite for the development of high performance dehalogenating bacterial agents. Herein, different domestication strategies were formulated for the main factors (nutrients and inocula) affecting the enrichment of OHRB, and the dehalogenation effect was verified with 2-chlorophenol and per/polyfluoroalkyl substances.
View Article and Find Full Text PDFFe(III) oxides are ubiquitous electron acceptors for anaerobic bioremediation, although their bioavailability was limited due to the passivation of secondary mineralization products. Here we found the solid S can be added to improve their bioavailability. Using lepidocrocite (γ-FeOOH), acetate and Geobacter sulfurreducens PCA as representatives of Fe(III) oxides, intermediate of pollutant degradation and microbes, a 6 times higher amount of FeOOH reduction in the presence of S was observed with a time needed for S reduction shortened by half.
View Article and Find Full Text PDFAs a result of the 2019 coronavirus pandemic, disinfection byproducts generated by the extensive use of chlorine disinfectants have infiltrated the aquatic environment, severely threatening ecological safety and human health. Therefore, the accurate monitoring of the biotoxicity of aqueous environments has become an important issue. Biocathode sensors are excellent choices for toxicity monitoring because of their special electroautotrophic respiration functions.
View Article and Find Full Text PDFBiochemical oxygen demand (BOD) is an important biochemical indicator for determining the degree of water pollution and guiding the design of wastewater treatment processes. BOD sensors based on microbial electrochemical technology can conduct real-time online monitoring of organic matter and have attracted extensive attention. However, research on microbial electrolytic cell (MEC)-type BOD sensors is at the stage of theoretical exploration.
View Article and Find Full Text PDFReducing the electrode spacing in bioelectrochemical systems (BESs) are widely reported to improve power output, which was mainly attributed to the decrease of ohmic resistance (R) for a long time. Here we found the change of endogenous electric field (EF) intensity was the key to improve electroactivity in response to a reduced electrode spacing, which also accelerated phenol biodegradation. Correlation and principal components analysis revealed that the microbial community of electroactive biofilm (EAB) was independent of R, while the EF intensity was found closely related to most of predominant genera.
View Article and Find Full Text PDFElectroactive biofilms have attracted increasing attention due to their unique ability to exchange electrons with electrodes. Geobacter spp. are widely found to be dominant in biofilms in acetate-rich environments when an appropriate voltage is applied, but it is still largely unknown how these bacteria are selectively enriched.
View Article and Find Full Text PDFHalogenated organic compounds are persistent pollutants, whose persistent contamination and rapid spread seriously threaten human health and the safety of ecosystems. It is difficult to remove them completely by traditional physicochemical techniques. In-situ remediation utilizing bioelectrochemical technology represents a promising strategy for degradation of halogenated organic compounds, which can be achieved through potential modulation.
View Article and Find Full Text PDFEnviron Sci Technol
November 2021
spp. are well-known exoelectrogenic microorganisms that often predominate acetate-fed biofilms in microbial fuel cells (MFCs) and other bioelectrochemical systems (BESs). By using an amplicon sequence variance analysis (at one nucleotide resolution), we observed a succession between two closely related species (98% similarity in 16S RNA), and , in the long-term studies (20 months) of MFC biofilms.
View Article and Find Full Text PDFThe biosynthesis of metal nanoparticles from precious metals has been of wide concern. Their antibacterial activity is a main bottleneck restricting the bacterial activity and reduction performance. Here, bio-electrochemical systems were used to harvest electroactive biofilms (EABs), where bacteria were naturally protected by extracellular polymeric substances to keep activity.
View Article and Find Full Text PDFAnaerobic ammonium oxidation coupled to Fe(III) reduction, known as Feammox, is a newly discovered nitrogen-cycling process, which serves an important role in the pathways of nitrogen loss in the environment. However, the specific types of microorganisms involved in Feammox currently remain unclear. In this study, we selected two groups of soil samples (paddy and mine), from considerably different habitats in South China, to acclimate Feammox colonies.
View Article and Find Full Text PDFAmmonium is one of the most common forms of nitrogen that exists in wastewater, and it can cause severe pollution when it is discharged without treatment. New technologies must be developed to effectively remove ammonium because conventional nitrification-denitrification methods are limited by the lack of organic carbon. Anaerobic ammonium oxidation coupled to Fe(III) reduction is known as Feammox, and is a recently discovered nitrogen cycling process.
View Article and Find Full Text PDFElectrotrophic bacteria on cathodes are promising substitutes to precious metals as oxygen reduction reaction catalysts in bioelectrochemical systems (BESs). Leading the anodic effluent to the biocathode has additional benefits of neutralizing pH and removing residual pollutants. However, the overflow of excessive organic pollutants inhibits the activity of autotrophic biocathodes.
View Article and Find Full Text PDFElectroactive biofilm (EAB) sensor had shown great potential in the field of early warning of toxicants in water because of the low-cost and broad-spectrum. However, the traditional calculation of sensitivity strongly relied on the time and concentration gradient which weakened time-efficiency of the sensor. Moreover, the sensitivity could be further improved to respond trace concentrations.
View Article and Find Full Text PDFHydrogen peroxide (HO)-based electrochemical advanced oxidation processes (EAOPs) have been widely attempted for various wastewater treatments. So far, stability tests of EAOPs are rarely addressed and the decay mechanism is still unclear. Here, three HO-based EAOP systems (electro-Fenton, photoelectro-Fenton, and photo+ electro-generated HO) were built for phenol degradation.
View Article and Find Full Text PDFBioelectrochemical systems (BESs) are widely investigated as a promising technology to recover bioenergy or synthesize value-added products from wastewaters. The performance of BES depends on the activity of electroactive biofilm (EAB). As the core of BES, it is still unclear how the EAB is formed from mixed inoculum, and how exoelectrogens compete with non-exoelectrogens.
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