Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values

Area of Science:

• Environmental Engineering
• Microbiology
• Materials Science

Background:

• Anammox (Anaerobic Ammonium Oxidation) process is key for nitrogen removal but requires stable nitrite-to-ammonium ratios.
• Partial nitritation pretreatment is often unstable, posing a challenge for Anammox efficiency.
• Wastewater influent typically has unsuitable nitrogen ratios for direct Anammox treatment.

Purpose of the Study:

• To investigate the buffering capacity of an Anammox-zeolite biofilter for unstable influent nitrogen loads.
• To assess the Anammox-zeolite system's performance under varying nitrite and ammonium concentrations.
• To evaluate the combined ion-exchange and biological removal capabilities.

Main Methods:

• A continuous-flow Anammox-zeolite biofilter was operated for 570 days.
• The system was subjected to irregular influent flows of nitrite and ammonium nitrogen.
• Performance was monitored by measuring nitrogen removal efficiencies and influent/effluent ratios.

Main Results:

• The Anammox-zeolite biofilter achieved stable and high nitrogen removal efficiencies (approx. 95%).
• The system effectively handled extreme NO2-N to NH4-N ratios (0 to infinity).
• Zeolite facilitated ammonium sorption during excess influent and desorption when ammonium was deficient, acting as a buffer.

Conclusions:

• An Anammox-zeolite biofilter effectively buffers influent nitrogen imbalances, ensuring stable Anammox process operation.
• Zeolite's ion-exchange properties are crucial for maintaining optimal conditions for nitrogen removal.
• This integrated system offers a robust solution for challenging wastewater treatment scenarios.