Modeling a granule-based anaerobic ammonium oxidizing (ANAMMOX) process.

Area of Science:

• Environmental Engineering
• Biotechnology
• Wastewater Treatment

Background:

• The anaerobic ammonium oxidation (ANAMMOX) process is crucial for nitrogen removal in wastewater.
• Granular upflow anaerobic sludge blanket (UASB) reactors offer potential for efficient ANAMMOX processes.
• Understanding ANAMMOX granule dynamics is key to optimizing reactor performance.

Purpose of the Study:

• To develop and validate a mathematical model for ANAMMOX in a granular UASB reactor.
• To investigate the impact of process parameters on ANAMMOX reactor performance.
• To explore diffusion dynamics within ANAMMOX granules.

Main Methods:

• Cultivation of ANAMMOX granules in a UASB reactor seeded with aerobic granules.
• Development of a mathematical model to describe the ANAMMOX process.
• Experimental validation of the model using 1-year reactor performance data.
• Microelectrode measurements to determine substrate micro-profiles within granules.

Main Results:

• The developed model accurately predicted the reactor's 1-year performance.
• Estimated ANAMMOX granule yield coefficient: 0.164 g COD g(-1) N; decay rate coefficient: 0.00016 h(-1).
• Optimal ANAMMOX granule diameter for nitrogen removal is 1.0–1.3 mm.
• Optimal nitrogen loading rate is 0.8 kg N m(-3) d(-1).
• Measured substrate micro-profiles matched model predictions.

Conclusions:

• The mathematical model provides a reliable tool for simulating and optimizing ANAMMOX processes in granular UASB reactors.
• Granule size and nitrogen loading rate are critical parameters for maximizing nitrogen removal efficiency.
• The study enhances understanding of diffusion dynamics within ANAMMOX granules.