Effect of dissolved oxygen concentration on nitrite accumulation in nitrifying sequencing batch reactor

Area of Science:

• Environmental Engineering
• Water Treatment Technology
• Biochemical Engineering

Background:

• Nitrification is crucial for ammonia removal in wastewater treatment.
• Nitrite accumulation can inhibit nitrification and requires careful management.
• Sequencing batch reactors (SBRs) are versatile for biological wastewater treatment.

Purpose of the Study:

• To investigate the impact of dissolved oxygen concentration on nitrite accumulation during nitrification in an SBR.
• To identify control parameters for minimizing nitrite buildup in SBR systems.

Main Methods:

• Utilized a mathematical model based on the Activated Sludge Model No. 3.
• Conducted laboratory-scale experiments in a sequencing batch reactor.
• Measured ammonium conversion under varying air flow rates to manipulate dissolved oxygen levels.

Main Results:

• Dissolved oxygen concentration significantly influences nitrite accumulation.
• Air flow rate was identified as an effective parameter for controlling nitrite levels.
• Nitrite accumulation was highly dependent on the volumetric mass-transfer coefficient (kLa) at low values, but less so at high values.

Conclusions:

• Optimizing air flow rate in SBRs allows for effective control of nitrite accumulation during nitrification.
• Understanding the relationship between dissolved oxygen and kLa is vital for managing nitrification processes and preventing nitrite buildup.