Insights into the azo dye decolourisation and denitrogenation in micro-electrolysis enhanced counter-diffusion biofilm system

• Published in: Bioresource technology Vol. 411; p. 131333
• Main Authors: Wang, Tianyi, Han, Xiaohang, Cheng, Yufei, Yang, Jiaxuan, Bai, Langming, Zeng, Weichen, Wang, Hesong, Cheng, Nuo, Zhang, Han, Li, Guibai, Liang, Heng
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2024
• Subjects: Dye wastewater; MABR; Micro-electrolysis; Nitrogen removal; Nitrogen removal; Dye wastewater; Micro-electrolysis; MABR
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131333

[Display omitted] •A counter-diffusion biofilm was constructed for AYR denitrogenation.•AYR occupied binding site of the residues caused menaquinone synthesis limitation.•Fe/C stimulated the expression of EC 3.1.2.28 to diverse the electron shuttles.•Encoded genes up-regulation promoted the AYR decolourisation and denitrogenation. In this study, electron transport pathways were activated and diversified by coupling counter-diffusion biofilms with micro-electrolysis for Alizarin yellow R (AYR) denitrogenation. Due to the binding of AYR to two residues of EC 4.1.3.36 with higher binding energy, the expression of EC 4.1.3.36 was down-regulated, causing the EC 3.1.2.28 and EC 2.5.1.74 for menaquinone synthesis (redox mediator) undetectable in Membrane aerated biofilm reactors (MABR). Spontaneous electron generation in the micro electrolysis-coupled MABR (ME-MABR) significantly activated two enzymes. Activated menaquinone up-regulated decolourisation related genes expression in ME-MABR, including azoR (2.12 log2), NQO1 (2.97 log2), wrbA (0.45 log2), and ndh (0.47 log2). The diversified electron flow pathways also promoted the nitrogen metabolism coding genes up-regulation, accelerating further inorganic nitrogen denitrogenation after AYR mineralisation. Compared to MABR, the decolourisation, mineralisation, and denitrogenation in ME-MABR increased by 25.80 %, 16.53 %, and 13.32 %, respectively. This study provides new insights into micro-electrolysis enhanced removal of AYR.