Search

A biofilm anode acclimated with growth media containing acetate, then acetate + methane, and finally methane alone produced electrical current in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for the bacterial domain (93%) in the biofilm anode, while methanogens ( Methanocorpusculum labreanum and Methanosaeta concilii ) accounted for 82% of the total archaeal clones in the biofilm. Fluorescence in situ hybridization (FISH) imaging clearly showed a biofilm of mixed bacteria and archaea, suggesting a syntrophic interaction between them for performing anaerobic oxidation of methane (AOM) in the biofilm anode. Measured cumulative coulombs were linearly correlated to the methane-gas concentration in the range of 10–99.97% (R 2 ≥ 0.99) when the measurement was sustained for at least 50 min Thus, cumulative coulombs over 50 min could be used to quantify the methane concentration in gas samples. [ABSTRACT FROM AUTHOR]

Conventionally, both a working and counter electrode are housed in a single cell to form an electrochemical device for quantification of various analytes. For reductive sensing of hydrogen peroxide, however, analyte losses due to oxidation and catalytic decomposition on the counter electrode are significant, rendering such devices unsuitable for continuous monitoring of analyte concentration changes over time. Further, only chemically inert materials such as platinum can be used to construct the counter electrode, where their high cost limits potential applications. To circumvent such issues, an anion-exchange membrane was employed to fabricate a two-chamber device housing each electrode in each individual chamber, to physically prevent the counter electrode from interfering with working electrode analysis. Such a design enables the use of sacrificial anodes as the counter electrodes, thereby significantly expanding the linear range of detection, improving sensitivity, and reducing device cost. [ABSTRACT FROM AUTHOR]

• In-sewer physiobiochemical processes cause wastewater quality variation. • Microbial activities in stabilized sewer deposits are spatiotemporally organized. • In-sewer processes are intertwined with the dynamic wastewater discharge. • Detection and control of volatile compounds and bioaerosols are still challenging. • Relationships among microbiome, water quality, and sediment erosion are not clear. In-sewer physio-biochemical processes cause significant variations of wastewater quality during conveyance, which affects the influent to a wastewater treatment plant (WWTP) and arguably the microbial community of biological treatment units in a WWTP. In wet weather, contaminants stored in sewer deposits can be resuspended and migrate downstream or be released during combined sewer overflows to the urban water bodies, posing challenges to the treatment facilities or endangering urban water quality. Therefore, in-sewer transformation and migration of contaminants have been extensively studied. The compiled results from representative research in the past few decades showed that biochemical reactions are both cross-sectionally and longitudinally organized in the deposits and the sewage, following the redox potential as well as the sequence of macromolecule/contaminant degradation. The sewage organic contents and sewer biofilm microorganisms were found to covary but more systematic studies are required to examine the temporal stability of the feature. Besides, unique communities can be developed in the sewage phase. The enrichment of the major sewage-associated microorganisms can be explained by the availability of biodegradable organic contents in sewers. The sewer deposits, including biofilms, harbor both microorganisms and contaminants and usually can provide longer residence time for in-sewer transformation than wastewater. However, the interrelationships among contaminant transformation, microorganisms in the deposits/biofilms, and those in the sewage are largely unclear. Specifically, the formation and migration of FOG (fat, oil, and grease) deposits, generation and transport of contaminants in the sewer atmosphere (e.g., H 2 S, CH 4 , volatile organic compounds, bioaerosols), transport and transformation of nonconventional contaminants, such as pharmaceuticals and personal care products, and wastewater quality variation during the biofilm rehabilitation period after damages caused by rains/storms are some topics for future research. Moreover, systematic and standardized field analysis of real sewers under dynamic wastewater discharge conditions is necessary. We believe that an improved understanding of these processes would assist in sewer management and better prepare us for the challenges brought about by climate change and water shortage. [Display omitted] [ABSTRACT FROM AUTHOR]

Thauera is a genus of denitrifying and phosphorus-accumulating bacteria used for removing nitrogen and phosphorus from wastewater. Dissolved oxygen is one of the main factors affecting denitrification and phosphorus accumulation, and there is currently little research on the oxygen sensing regulation mechanism of Thauera bacteria. We studied denitrifying phosphorus accumulation and gene transcription expression of Thauera sp. RT1901 in anaerobic, microaerobic, and aerobic environments and analyzed the protein structure and regulation mode of two oxygen-sensing systems. The results showed that the strain could achieve the similar denitrification and phosphorus accumulation effect in microaerobic environment as in anaerobic environment. Transcriptome analysis showed that as the oxygen concentration continued to rise, the core carbon and phosphorus metabolism pathways of the strain remained unchanged, and the respiratory system shifted from nitrate respiration to aerobic respiration, thereby inhibiting the denitrification pathway. The fumarate nitrate reduction (FNR) protein and FixLJ two-component system performed oxygen sensing to jointly regulate the expression of respiratory genes. The FNR protein formed a dimer in an anaerobic environment, activating denitrification-related genes and inhibiting cytochrome oxidase-related genes. The FixLJ system conducted signal transduction through phosphorylation in a low oxygen environment and activated the transcription of the fixK gene. The FixK protein has a similar structure and function as the FNR protein but is not directly affected by oxygen. These results reveal the oxygen sensing regulation mechanism of Thauera sp. RT1901 in the denitrification and phosphorus accumulation process, providing new insights for further studying the functions of this genus of bacteria in wastewater treatment systems. [Display omitted] • The N and P removal mechanisms of Thauera are evaluated in different oxygen environments. • Thauera regulates the respiratory chain and transport to adapt to oxygen changes. • The FNR protein performs oxygen sensing and regulates in anaerobic and aerobic environments. • The FixLJ system performs oxygen sensing and regulates in microaerobic and aerobic environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel heterogeneous Fenton-like process driven by visible light is proposed. • Reactivity is strongly enhanced without the use of reducing agents and TiO 2 modification. • Fe(III) reduction for PS activation can be accomplished via LMCT in organic-TiO 2 -Fe(III). • It can be operated at low iron dosage and neutral conditions against Fenton system. • The excellent and long-lasting catalytic performance is mediated via synergistic effect. Efficient transformation of Fe(III) to Fe(II) enhances the efficiency of persulfate-based Fenton-like process (e.g., Fe(II)-PS system). Here, we developed a novel heterogeneous Fenton-like system driven by visible light (organic-Fe(III)-PS-TiO 2 -Vis) for effective reduction of Fe(III), activation of PS and degradation of organic pollutants without the need for external reducing agents or modifications in TiO 2. The visible light-induced ligand-to-metal (organic-to-TiO 2) charge transfer (LMCT) remarkably boosting Fe(III) reduction to increase reactive oxygen species (ROS) via PS activation, and further enhanced the self-degradation and mineralization of various organics, including phenolics (bisphenol A and phenol), antibiotics (ibuprofen and tetracycline), and dyes (methylene bule and rhodamine B). Compared with traditional Fe(II)-PS and Fe(II)–H 2 O 2 systems, the organic-Fe(III)-PS-TiO 2 -Vis process requires a lower dosage of iron salt. The effective pH range has been broadened to neutral conditions due to effective prevention of Fe(III) precipitation and rapid circulation of Fe(III)/Fe(II). The comprehensive mechanistic study indicated that a synergistic effect was generated via Fe(III) reduction, PS activation, ROS generation and organic decomposition, resulting in sustainable and excellent catalytic performance of this novel Fenton-like process. Further, the results of cycling experiments and tests involving real industrial wastewater highlight the enormous potential of the proposed LMCT-mediated heterogeneous Fenton-like process in environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-Kapok has been made by easy hydrothermal method. • Fe-Kapok showed Fe positive impact for As (V) removal. • High and fast As (V) adsorption. • Fe-Kapok could be regenerated and reused several times. Arsenic (As) is one of the most toxic metals for human health. In the present work, kapok fibers were modified using iron Fe(III) to enhance As(V) adsorption and then characterized using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The impacts of pH, dose of adsorbent, contact time, initial concentration, temperature, and coexisting ions on the adsorption of As(V) onto Fe-modified kapok fiber (Fe-kapok) surfaces were investigated. The results showed that the adsorption process fit more to the Langmuir isotherm equation and pseudo second kinetic equation, thus demonstrating that the adsorption was an endothermic, spontaneous, monolayer chemisorption process with some disorder at the solid/solution interface. The adsorption process was controlled by the film diffusion step, and the maximum adsorption capacity of Fe-kapok was calculated to be approximately 367 µg/g. Further study showed that after 8 adsorption/desorption cycles with 1 regeneration cycle, Fe-kapok was still able to remove 45% of the arsenic (100 µg/L) present in the water. A notable negative impact on the removal of As(V) from water was linked to the concentrations of SO 4 2- and PO 4 3- in the water. [ABSTRACT FROM AUTHOR]