Static magnetic field enhances respiratory dissimilatory nitrate reduction to ammonium over denitrification in
Zhongling Yuan1, Wei Zeng1, Mengjia Zhan1
1National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China.
Abstract:
Dissimilatory nitrate reduction to ammonium (DNRA) represents a sustainable strategy for nitrogen resource recovery from wastewater, yet selectively enhancing DNRA over denitrification in sulfide-based autotrophic systems remains challenging. This study investigates the impact of static magnetic field (SMF, 0-100mT) on nitrate reduction pathways in sulfide-rich wastewater. SMF elevated DNRA efficiency to 41.8 % with an influent sulfide concentration of 200 mgS/L (S/N ratio of 3:1) under 30 mT, supported by nrfA upregulation (7.6 × 1010 vs. 4.0 × 107 copies/g SS in control). 15N isotope labeling and enhanced direct extracellular electron transfer via cytochrome c and conductive pili confirmed that SMF preferentially drove nitrate flux toward DNRA. Metagenomics revealed that SMF enriched DNRA taxa (Aeromonas, Shewanella) and enhanced their synergy with Thiobacillus, improving metabolic flexibility. This work unveils microbial competition mechanisms between denitrification and DNRA in sulfide-based systems and proposes an innovative SMF-assisted ammonium recovery approach, advancing the understanding of sulfide-based nitrogen removal technologies.
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