Mainstream anammox in inverse fluidized bed bioreactors

Area of Science:

• Environmental Biotechnology
• Wastewater Treatment Engineering
• Microbial Ecology

Background:

• Mainstream anammox processes face limitations in startup, stability, and efficiency.
• Inverse fluidized bed bioreactors offer potential for enhanced biomass retention and hydrodynamics.

Purpose of the Study:

• To integrate mainstream anammox into inverse fluidized bed bioreactors (Invammox).
• To overcome limitations of traditional anammox and fluidized bed processes.
• To develop a scalable and energy-efficient nitrogen removal platform.

Main Methods:

• Developed a rapid biofilm attachment protocol (<3 hours).
• Optimized initial particle loading (30% reactor volume) and seed biomass (1 g VSS/L).
• Implemented internal liquid recirculation to manage biofilm thickness and enhance activity.

Main Results:

• Invammox demonstrated spontaneous hydrodynamic uniformity and avoided biofilm overgrowth.
• The system maintained resilient stability for over 6,000 hours with exceptional biomass retention.
• Achieved specific anammox activity up to 0.61 kg NH₄⁺-N/kg VSS·d, threefold higher than granular anammox.
• A full-scale system showed a 62% reduction in reactor volume for treating 1.5 MGD municipal wastewater.

Conclusions:

• Invammox represents a state-of-the-art platform for mainstream anammox and partial nitrification/anammox.
• The process offers a scalable, energy-efficient paradigm for biological nitrogen removal.
• This integration overcomes longstanding limitations, paving the way for advanced wastewater treatment.