Synergistic interactions between anammox and dissimilatory nitrate reducing bacteria sustains reactor performance
Christian White1, Edmund Antell1, Sarah L Schwartz1
1Department of Civil & Environmental Engineering, University of California, Berkeley, Berkeley, CA, United States.
Frontiers in Microbiology
|August 28, 2023
Summary
Altering the ammonium to nitrite ratio in wastewater treatment impacts microbial communities. A mutualistic relationship between anammox and dissimilatory nitrate reduction to ammonium (DNRA) bacteria supports nitrogen removal efficiency.
Area of Science:
- Environmental Microbiology
- Wastewater Treatment Technologies
- Bioreactor Microbial Ecology
Background:
- Anaerobic ammonium oxidizing (anammox) bacteria are crucial for nitrogen removal in wastewater sidestreams.
- Anammox bacteria interact with heterotrophic bacteria, influencing nitrogen removal efficiency.
- Influent ammonium to nitrite (NH4+:NO2-) ratios significantly affect anammox process performance.
Purpose of the Study:
- To investigate the impact of variable NH4+:NO2- ratios on the microbial ecology of anammox bioreactors.
- To understand the relationship between anammox bacteria and other microbial communities under different substrate conditions.
- To assess how microbial community shifts correlate with nitrogen removal efficiency.
Main Methods:
- Utilized a lab-scale anammox membrane bioreactor (MBR).
- Manipulated influent NH4+:NO2- ratios over the experimental period.
- Employed 16S rRNA gene and shotgun metagenomic sequencing for microbial community analysis.
Main Results:
- Ammonium removal efficiency varied with NH4+:NO2- ratios, decreasing at lower ratios but recovering with adjustments.
- Nitrogen removal efficiency remained relatively stable despite fluctuations in ammonium removal.
- Relative abundance of Planctomycetes (anammox bacteria) decreased, while bacteria with DNRA genes (nrfAH) increased at lower ratios.
Conclusions:
- A high relative abundance of DNRA bacteria correlated with sustained bioreactor performance, suggesting a mutualistic interaction with anammox bacteria.
- Understanding these microbial interactions is key to optimizing bioreactor operation under variable nitrogen loading conditions.
- The study highlights the resilience of nitrogen removal despite shifts in microbial composition due to altered substrate ratios.
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