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<p>Exoelectrogenic biofilms capable of extracellular electron transfer are important in advanced technologies such as those used in microbial electrochemical remediation systems (MERS) Few bacterial strains have been, nevertheless, obtained from MERS exoelectrogenic biofilms and characterized for bioremediation potential. Here we report the identification of one such bacterial strain, Citrobacter sp. KVM11, a petrophilic, iron reducing bacterial strain isolated from hydrocarbon fed MERS, producing anodic currents in microbial electrochemical systems. Fe(III) reduction of 90.01 ± 0.43% was observed during 5 weeks of incubation with Fe(III) supplemented liquid cultures. Biodegradation screening assays showed that the hydrocarbon degradation had been carried out by metabolically active cells accompanied by growth. The characteristic feature of diazo dye decolorization was used as a simple criterion for evaluating the electrochemical activity in the candidate microbe. The electrochemical activities of the strain KVM11 were characterized in a single chamber fuel cell and three electrode electrochemical cells. The inoculation of strain KVM11 amended with acetate and citrate as the sole carbon and energy sources has resulted in an increase in anodic currents (maximum current density) of 212 ± 3 and 359 ± mA/m² with respective coulombic efficiencies of 19.5 and 34.9% in a single chamber fuel cells. Cyclic voltammetry studies showed that anaerobically grown cells of strain KVM11 are electrochemically active whereas aerobically grown cells lacked the electrochemical activity. Electrobioremediation potential of the strain KVM11 was investigated in hydrocarbonoclastic and dye detoxification conditions using MERS. About 89.60% of 400 mg l^-1 azo dye was removed during the first 24 h of operation and it reached below detection limits by the end of the batch operation (60 h). Current generation and biodegradation capabilities of strain KVM11 were examined using an initial concentration of 800 mg l^-1 of diesel range hydrocarbons (C9-C36) in MERS (maximum currentdensity 50.64 ± 7 mA/m²; power density 4.08 ± 2 mW/m², 1000 ω, hydrocarbon removal 60.14 ± 0.7%). Such observations reveal the potential of electroactive biofilms in the simultaneous remediation of hydrocarbon contaminated environments with generation of energy.</p

Emergy Analysis and Life Cycle Assessment for Evaluating the Sustainability of Solar-Integrated Ecotechnologies in Winery Wastewater Treatment

Innovative approaches in sustainable wastewater management are vital in addressing climate change. This study introduces a novel assessment of solar-integrated ecotechnologies, focusing on the constructed wetland (CW) and microalgae-based systems, viz., high-rate algal pond (HRAP) and photobioreactor (PBR), for the treatment of winery wastewater. Utilizing Emergy analysis and life cycle assessment (LCA), we comprehensively compared these technologies in terms of environmental impact, resource recovery efficiency, and circular economy integration. Our Emergy analysis of the HRAP revealed a substantial reliance on renewable inputs (94%) and its lower nonrenewable resource consumption compared to the CW system. The Emergy sustainability index initially indicated a preference for the CW system (42.93 sej year–1; sej = solar emjoule), but deeper analysis showed greater sustainability in the HRAP (341 sej year–1) and PBR (118 sej year–1). LCA results further revealed that PBR systems had a significant land-use footprint, impacting other environmental indices such as photochemical ozone formation and freshwater eutrophication. Additionally, the HRAP and PBR demonstrated a marked reduction in greenhouse gas emissions (−24800 and −23700 kg of CO2-eq, respectively) compared to the CW system (320 kg of CO2-eq). Life cycle cost analysis underscored the economic viability of these systems, with Scenario 3 (PBR) emerging as the most economically sustainable, exhibiting the highest internal rate of return (IRR) at 21.11% and a positive net present value after 20 years. Conversely, Scenario 1 (CW system), with its significant initial investment of AU$741220, showed no IRR due to the absence of revenue generation. Importantly, our study introduces circularity index scores as a novel element, revealing that the HRAP and PBR effectively incorporate circularity measures across various impact categories. These measures had moderate impacts, as indicated by scores close to but not exceeding 0.10, whereas the CW system showed no significant improvement, highlighting the need for more robust circularity strategies. Overall, our integrated framework provides a holistic view of the environmental impact and economic aspects, emphasizing the potential of solar-integrated microalgal systems in promoting circular (bio)economy practices and sustainable environmental management in the viticulture sector

Manganese(II)-Catalyzed and Clay-Minerals-Mediated Reduction of Chromium(VI) by Citrate

Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr­(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn­(II) and clay minerals (montmorillonite and kaolinite) reduce Cr­(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn­(II) (182.02 μM) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr­(VI) (192.32 μM) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn­(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr­(III). This study reveals the underlying mechanism of the Mn­(II)-induced reduction of Cr­(VI) by organic ligand in the presence of clay minerals under certain environmental conditions

DataSheet1_A modified TOP assay to detect per- and polyfluoroalkyl substances in aqueous film-forming foams (AFFF) and soil.docx

Total oxidisable precursor (TOP) assay can oxidise some per- and polyfluoroalkyl substances (PFASs) and their precursors, most of which cannot be quantitatively detected so far, and convert them to detectable PFASs, such as perfluoroalkyl acids (PFAAs). However, the conversion is constrained by the complexity of the target samples, including co-existent organics, unknown PFAS precursors, and background. In this study, the TOP assay is modified to increase the oxidation and conversion efficiency by changing the initial concentration of target sample, increasing oxidising doses, time, temperature, etc. The modified TOP assay is applied to test several aqueous film-forming foams (AFFF) and a PFAS-contaminated soil extract. The sum concentrations of the detectable PFASs are increased by up to ∼534× in the AFFF samples and ∼7× in the PFAS-contaminated soil extract. The detectable fluorotelomer sulfonate (FTS, such as 6:2/8:2 FTS) is accounted as an oxidation indicator to monitor the oxidation and conversion progress of the oxidisable PFASs precursors to the detectable PFASs. Overall, the modified TOP assay could be an appropriate method for identifying missing PFASs mass in complex matrices by detecting the PFASs precursors effectively.</p