Exogenous magnetite (Fe₃O₄) nanoparticles for rapid start-up of anammox bioreactor under high nitrogen-loading conditions: Instant boost to anammox activity

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Anaerobic ammonium oxidation (anammox) is a key process for nitrogen removal in wastewater treatment.
• Optimizing anammox performance is crucial for efficient and sustainable wastewater management.
• Exogenous materials can potentially enhance microbial processes in bioreactors.

Purpose of the Study:

• To investigate the impact of exogenous magnetite particles (Fe3O4) on anammox performance.
• To evaluate the influence of magnetite on nitrogen removal rates and granulation.
• To understand the biochemical mechanisms underlying magnetite's effect on anammox.

Main Methods:

• Operation of two sequencing batch bioreactors: magnetite-anammox (M-AMX) and control-anammox (C-AMX).
• Testing at varying nitrogen loading rates (NLR): 0.4 and 0.7 kgN.m-3.d-1.
• Analysis of nitrogen removal efficiency, granulation, and microbial community composition.

Main Results:

• The M-AMX system achieved 80% nitrogen removal in 30 days, compared to 50% for C-AMX.
• M-AMX demonstrated superior performance at higher NLR (0.7 kgN.m-3.d-1), reaching 90% removal in 100 days.
• Magnetite incorporation led to increased ATP, heme c, and hydrazine synthase, correlating with enhanced nitrogen removal.

Conclusions:

• Magnetite particles (Fe3O4) significantly improve granulation and nitrogen removal in anammox processes.
• The M-AMX system offers a promising approach for rapid and efficient nitrogen removal.
• Fe3O4 can be a beneficial additive for enhancing anammox bioreactor performance.