Recovery of Iron-Dependent Autotrophic Denitrification Activity from Cell-Iron Mineral Aggregation-Induced Reversible...

Area of Science:

• Environmental Science
• Microbiology
• Chemical Engineering

Background:

• Iron-dependent autotrophic denitrification (IDAD) is a promising wastewater treatment for low C:N ratios.
• Performance deterioration limits the long-term application of IDAD systems.

Purpose of the Study:

• To uncover the cause of IDAD performance deterioration.
• To provide a viable solution for restoring and maintaining IDAD stability.

Main Methods:

• Batch tests were conducted to analyze IDAD sludge activity.
• Microbial cell and iron-bearing mineral aggregation mechanisms were investigated.
• Low-intensity ultrasound treatment was applied to assess its effect on IDAD activity.

Main Results:

• Aggregation of microbial cells and iron-bearing minerals, mediated by extracellular polymeric substances, was identified as the cause of inhibition.
• Ultrasound treatment effectively disintegrated these aggregates, restoring IDAD activity.
• An ultrasonication-assisted IDAD bioreactor showed a 72.3% enhancement in nitrogen removal efficiency and improved operational stability.

Conclusions:

• The study elucidates the mechanism behind IDAD performance decline.
• Low-intensity ultrasound offers a simple and effective strategy to maintain the long-term stability and efficiency of IDAD processes.