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

## TL;DR

A new method using vanadium-stressed bacteria improves wastewater treatment by removing ammonia and recovering vanadium, supporting sustainable mining.

## Contribution

A bioaugmentation strategy using vanadium-acclimated Pseudomonas sp. S.P-1 achieves high ammonia removal and vanadium recovery.

## Key findings

- Pseudomonas sp. S.P-1 achieved >99.25% ammonia removal under optimized conditions.
- Vanadium stress enhanced microbial biosorption and metabolic activity for ammonia conversion.
- The process enabled simultaneous pollution control and vanadium recovery with 89.2% efficiency.

## Abstract

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 Pseudomonas 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.