Work

Molecular insights into dye decolorization performance and mechanisms under carbon limited conditions in a membrane aeration-based bioelectrochemical system

Year: 2025

Type: article

Abstract: Bioelectrochemical systems (BES) is a promising strategy for azo dyes decolorization enhancement in carbon-limited condition, but decolorization products need further aerobic mineralization. Here, a counter-diffusion biofilm-supported BES (E-MABR) was designed to achieve the decolorization, mineralization and denitrogenation of Alizarin Yellow R (AYR) in electron-deficient wastewater. The introduction of electrodes facilitated the secretion of extracellular polymeric substances (EPS), particularly proteins (PN), whose content in the cathodic biofilm was 2.5 ± 0.2 times higher than that in the MABR. Additionally, electrical stimulation enriched electroactivity bacteria (e.g. Geobacter ) and azo dyes metabolism contributor (e.g., Thauera and Dechloromonas ), and significantly upregulated the expression of decolorization-related genes, particularly azoR (1.2 log 2 ) in the cathodic biofilm. The increased β-sheet proportions of protein structures in the anode (22.2 ± 1.5 %) and cathode (20.1 ± 1.7 %) promoted the exposure of hydrophobic groups in amino acid; consequently, more hydrogen bonds formed, leading to stronger hydrophobic interactions in molecular dynamic simulations. Under the electric field stress, the total binding free energy between azoR and AYR declined to −32.6 kJ·mol⁻¹, enhancing the stability of the complex and creating a favourable environment for AYR degradation. Finally, under carbon-limiting conditions, E-MABR significantly promoted AYR decolorization efficiency, mineralization efficiency, and total nitrogen removal by 32.4 ± 2.3 %, 29.4 ± 3.6 %, and 18.4 ± 2.0 %, respectively, compared to MABR.

Source: Water Research

DOI: 10.1016/j.watres.2025.123325