Precise H2 supply enables quantitative control of on-demand deep nitrate removal while preserving denitrification
Ge Yan1, Zhen-Xiang Jiang1, Jia-Le Wu1
1State Key Laboratory of Water Pollution Control and Green Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China; Institute for the Environment and Health, Nanjing University Suzhou Campus, Suzhou, 215163, China.
Water Research
|July 31, 2026
Summary
Precise control of deep nitrate removal for water reuse is now possible. Membrane-mediated hydrogen supply allows on-demand hydrogenotrophic denitrification, matching hydrogen delivery to target nitrate levels without harmful byproducts.
Area of Science:
- Environmental Engineering
- Microbiology
- Water Treatment
Background:
- Industrial water reuse demands precise control of deep nitrate (NO3-) removal.
- Conventional denitrification struggles to meet varied target NO3- concentrations.
Purpose of the Study:
- To demonstrate on-demand deep hydrogenotrophic denitrification using membrane-mediated hydrogen (H2) supply.
- To quantitatively match H2 supply with targeted NO3- removal for industrial water reuse.
Main Methods:
- Continuous operation of an H2-based membrane biofilm reactor (H2-MBfR) for 180 days.
- Tuning effluent NO3- concentrations by adjusting H2 transfer flux.
- Metagenomic analysis of biofilm communities.
Main Results:
- Effluent NO3- concentrations were predictably tuned from 0.1 to 4.5 mg-N/L by reducing H2 flux.
- H2-limited conditions ensured complete denitrification, preventing nitrite, nitric oxide, nitrous oxide, or ammonium accumulation.
- Complete hydrogenotrophic denitrifiers dominated the biofilm (92-97% MAG abundance).
- H2 over-supply led to increased effluent COD due to organic matter production.
Conclusions:
- Membrane-mediated H2 supply enables quantitative control of deep denitrification.
- Precise H2 regulation prevents byproduct accumulation and manages effluent COD.
- This method offers a mechanistic basis for balancing nitrate removal, water quality, and operational costs.
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