Comparing different reactor configurations for Partial Nitritation/Anammox at low temperatures.

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Partial Nitritation/Anammox (PN/A) is effective for nitrogen removal from warm, concentrated wastewater.
• Current research focuses on applying PN/A to cooler, dilute municipal wastewater.
• Low temperatures (10-20°C) present a significant challenge for PN/A processes.

Purpose of the Study:

• To investigate the impact of temperature reduction on PN/A performance.
• To compare the behavior of different biomass configurations under realistic temperature gradients.
• To identify optimal biomass geometries for low-temperature PN/A.

Main Methods:

• Four lab-scale reactors with different biomass configurations (suspended, granular, biofilm) were operated.
• A simulated seasonal temperature gradient from 20°C down to 10°C was applied.
• Synthetic wastewater was used to isolate PN/A process behavior.

Main Results:

• Anammox activity in suspended biomass declined significantly at 15°C.
• Granular biomass and biofilms on carriers maintained anammox activity down to <13°C.
• Thicker biofilms showed greater resilience and adaptation to low temperatures compared to thinner biofilms.

Conclusions:

• Biomass geometry is critical for PN/A efficiency in cold conditions.
• Granular and biofilm carriers are superior to suspended biomass for low-temperature PN/A.
• Biofilm thickness influences resilience and adaptation to temperature fluctuations in PN/A systems.