Vanadium Stress-Driven Microbial Acclimation Enhances Biological Denitrification in Recycling of Vanadium-Containing Industrial Wastewater

Recirculation in vanadium mining enhances resource efficiency but risks ammonia nitrogen (NH₃-N) accumulation, severely compromising leaching yields. To address this bottleneck, we developed a bioaugmentation strategy using <i>Pseudomonas</i> sp. S.P-1 acclimated to vanadium stress. Under optimized conditions (sodium citrate as a carbon source, C/N = 5, 5% inoculum, and pH = 8), the strain achieved exceptional NH₃-N (2000 mg·L^-1) removal (>99.25% within 16 days; residual NH₄⁺ < 15 mg·L^-1), 12.7% higher than the original bacteria. Mechanistic studies revealed that vanadium exposure triggered dual adaptive responses: enhanced biosorption via the stimulated synthesis of extracellular polymeric substances (EPS) enriched with negatively charged functional groups (C=O, -COOH-, and C-N), improving NH₄⁺ adsorption capacity, and metabolic activation via an elevated transmembrane electrochemical potential and an accelerated substrate uptake due to cell membrane permeability, while up-regulation of ammonia monooxygenase (AMO) activity (123.11%) facilitated efficient NH₄⁺→NH₂OH conversions. Crucially, this bio-process enabled simultaneous NH₃-N degradation (89.2% efficiency) and vanadium recovery, demonstrating its dual role in pollution control and critical metal recycling. By integrating microbial resilience with circular economy principles, our strategy offers a scalable prototype for sustainable vanadium extraction, aligning with low-carbon metallurgy demands in clean energy transitions. This study investigated the ability of vanadium stress to enhance microbial ammonia nitrogen metabolism, and by acclimatizing S.P-1 to vanadium-containing solutions, we aimed to address the dual problems of NH₃-N accumulation and vanadium toxicity in wastewater recirculation.