Anammox sludge preservation: Preservative agents, temperature and substrate

Area of Science:

• Environmental Microbiology
• Wastewater Treatment
• Biotechnology

Background:

• Enrichment and preservation of anaerobic ammonium oxidation bacteria (AnAOB) are critical for their practical application in wastewater treatment.
• Current methods face limitations, hindering the widespread use of AnAOB in bioreactors.

Purpose of the Study:

• To evaluate traditional and emerging preservative agents for AnAOB-dominant sludge.
• To determine optimal preservation strategies at different temperatures and consider substrate effects.

Main Methods:

• Tested preservative agents including EPS + N2H4, betaine, glycerol, and trehalose.
• Assessed sludge preservation at 4°C and room temperature.
• Analyzed relative anammox activities (rAA) and absolute abundances of the hzsA gene.

Main Results:

• Betaine or glycerol at 4°C emerged as the optimal preservation strategy.
• Relative anammox activities increased by 145.26% (betaine) and 158.30% (glycerol).
• Absolute abundances of the hzsA gene increased by 339% (betaine) and 46% (glycerol).

Conclusions:

• Optimal strategies for preserving anammox granular sludge at low temperatures were identified.
• Despite changes in granular properties and microbial communities, anammox granule performance was effectively restored.
• This study provides practical insights for enhancing AnAOB sludge preservation.