An innovative U-shaped sludge bed anammox process for nitrogen removal

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Engineering

Background:

• Conventional anammox reactors can be complex to operate.
• Efficient nitrogen removal is crucial for environmental protection.

Purpose of the Study:

• To evaluate the performance of an innovative U-shaped sludge bed reactor for nitrogen removal.
• To investigate the bacterial community composition in the reactor.
• To model the nitrification and anammox processes.

Main Methods:

• Operation of a U-shaped sludge bed reactor for approximately 500 days.
• Analysis of nitrogen removal rates and total nitrogen loading rates.
• 16S rRNA gene pyrosequencing for bacterial community analysis.
• Mathematical modeling of nitrification and anammox processes.

Main Results:

• Achieved a nitrogen removal rate of approximately 85% at a loading rate of 0.54 kg N/m³d.
• Identified the coexistence of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and anammox bacteria (Brocadia).
• Model simulation indicated oxygen depletion driving anammox bacteria growth under anaerobic conditions.

Conclusions:

• The U-shaped sludge bed reactor offers a cost-effective and simplified approach for anammox processes.
• Simultaneous growth and coexistence of AOB, NOB, and anammox bacteria are feasible in this reactor design.
• The reactor's performance is influenced by oxygen availability, favoring anammox bacteria under anaerobic conditions.