Biological nitrogen removal with enhanced phosphate uptake in a sequencing batch reactor using single sludge system

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Simultaneous biological phosphorus and nitrogen removal is crucial for wastewater treatment.
• Optimizing nutrient removal often involves complex reactor configurations and operational strategies.
• Phosphorus-Accumulating Organisms (PAOs) play a key role in biological phosphorus removal.

Purpose of the Study:

• To investigate simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake.
• To evaluate the performance of an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)2 SBR).
• To explore the use of nitrite as an electron acceptor for anoxic phosphate uptake and real-time control strategies.

Main Methods:

• Utilized an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)2 SBR) system.
• Accumulated phosphorus-accumulating organisms (PAOs) capable of denitrification in a single sludge system.
• Introduced an anoxic phase to enhance anoxic phosphate uptake and employed on-line sensors for real-time control.

Main Results:

• Achieved stable and high removal efficiencies: 92% TOC, 88% total nitrogen, and 100% phosphorus.
• Increased the ratio of anoxic to aerobic phosphate uptake capacity from 11% to 64%.
• Found nitrite to be an effective electron acceptor for anoxic phosphate uptake, even faster than nitrate.
• Demonstrated that real-time control using on-line sensors improved nutrient removal compared to fixed-time operation.

Conclusions:

• The (AO)2 SBR system is effective for simultaneous biological phosphorus and nitrogen removal.
• Anoxic phosphate uptake can be significantly enhanced by introducing an anoxic phase and utilizing nitrite.
• Real-time control based on on-line sensor data optimizes the performance of the (AO)2 SBR for nutrient removal.