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Updated: Jun 12, 2026

A Dual-Functional Electroactive Filter Towards Simultaneously Sb(III) Oxidation and Sequestration
Published on: December 5, 2019
Nitrate reshapes electron partitioning and Se0 formation during continuous electro-microbial treatment of mixed
Adriana Riveros1, Hyejeong Kwon1, Christopher A Impellitteri2
1Department of Civil, Construction, and Environmental Engineering, The University of Alabama, Tuscaloosa, AL 35487, United States.
Abstract:
Selenium in flue-gas-desulfurization (FGD) wastewater occurs as mixed selenate and selenite oxyanions, and requires both aqueous removal and reduction to elemental selenium to prevent secondary waste generation. Here, we introduce a continuous-flow electro-microbial platform that couples flow-electrode capacitive deionization (FCDI) with bio-electrochemical systems (BES) to achieve voltage-driven removal and bio-mediated reduction within a compact reactor configuration. During 41 days of operation treating mixed selenium oxyanions (10 mg Se L⁻¹ each) in fortified water samples with FGD-relevant nitrate concentrations (20 mg L⁻¹), the system achieved removal efficiencies of 84-95% for selenite and 54-78% for selenate. Nitrate unexpectedly enhanced apparent elemental selenium yield from 70% to 99% under 2 V, but decreased selenium-specific Faradaic efficiency from 20% to 8%, likely due to a combination of electron flux diversion and co-respiration between nitrogen and selenium oxyanions. Metagenomics suggested that genes associated with indirect selenium transformation (cysIJ, trxA/B, gshA/B, and ybbN) were 45-115x more abundant than genes encoding dedicated selenate reductases. Together, these results demonstrate FCDI-BES as a promising platform for treating selenium and potentially other redox-active oxyanions and highlight the importance of studying electron-acceptor competition in similar systems.
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