Factors affecting nitrogen removal by nitritation/denitritation.

Area of Science:

• Environmental Science
• Water Treatment Engineering
• Microbiology

Background:

• Wastewater treatment often faces challenges with high nitrogen concentrations and low COD/N ratios.
• Nitrogen removal via nitrite offers advantages in specific wastewater streams like sludge liquor.
• Sludge liquor's unique characteristics make it suitable for specialized nitrogen removal processes.

Purpose of the Study:

• To investigate the efficiency of nitrogen removal from high-strength wastewater using nitrite.
• To identify key factors influencing the efficiency of nitrogen removal via nitrite.
• To evaluate the impact of pH control and primary sludge addition on the process.

Main Methods:

• Utilizing sequencing batch reactor (SBR) technology for wastewater treatment.
• Treating wastewater with high ammonium (NH4+) concentrations (above 1 g/l).
• Employing primary sludge as an internal organic substrate source for denitritation.

Main Results:

• Key factors influencing process efficiency include pH, and ammonium/ammonia (NH4+/NH3) and nitrite/nitrous acid (NO2-/HNO2) concentrations.
• Efficient oxidation of ammonium to nitrite was achieved with minimal nitrate production.
• Denitritation was controllable by primary sludge dosing, achieving complete removal under optimal conditions.

Conclusions:

• Nitrogen removal via nitrite in sludge liquor is feasible and advantageous.
• Process efficiency is significantly influenced by pH and substrate availability.
• Two operational strategies exist: lower cost with partial removal (no pH control) or higher cost with complete removal (pH control).