Background ion shift induces microbial compensatory and structural remodeling in anammox granules
Ji Qi1, Qicheng Zhou1, Zhaolang Ye1
1School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University), Guangzhou 510275, PR China.
Bioresource Technology
|July 21, 2026
Summary
Stable anammox treatment depends on robust granules. Cation availability is crucial for granule stability and preventing biomass washout, even with compensatory bacterial responses. Ionic compatibility ensures reactor function.
Area of Science:
- Environmental microbiology
- Wastewater treatment engineering
- Biogeochemistry
Background:
- Stable municipal anammox (anaerobic ammonium oxidation) treatment relies on retaining slow-growing bacteria in robust granules.
- The influence of background cation availability on the stability of mineral-associated granules is not well understood.
Purpose of the Study:
- To investigate how influent hydrochemistry, specifically cation availability, impacts anammox granule stability and reactor performance.
- To elucidate the mechanisms behind granule destabilization and performance deterioration under cation-limited conditions.
Main Methods:
- Parallel continuous-flow anammox reactors were operated under contrasting cation conditions (control vs. cation-limited).
- Nitrogen removal efficiency (NRE), specific anammox activity, bacterial viability, granule structure, surface hydrophobicity, and settleability were monitored.
- Microbial community composition and network analysis were performed, with PICRUSt2 used for pathway predictions.
Main Results:
- Cation-limited conditions led to a significant decline in NRE (from >80% to 49%) due to granule destabilization and biomass washout.
- Metabolic activity of anammox bacteria remained viable, indicating structural failure rather than impaired function.
- Compensatory responses like EPS accumulation were insufficient to prevent structural collapse; microbial community structure shifted, and network connectivity decreased.
Conclusions:
- Background cation availability is critical for maintaining anammox granule structural integrity and reactor stability.
- Cation deficiency destabilizes granules by affecting mineral association, hydrophobicity, and settleability, leading to performance loss.
- Ionic compatibility is a key factor for robust mainstream anammox operation, influencing biomass retention and overall treatment efficiency.
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