Low temperature biological phosphorus removal and partial nitrification in a pilot sequencing batch reactor system

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Microbial Ecology

Background:

• Biological nutrient removal is crucial for sustainable wastewater management.
• Partial nitrification and biological phosphorus removal offer cost-effective solutions.
• Sequencing batch reactors (SBRs) are versatile for nutrient removal processes.

Purpose of the Study:

• To investigate the feasibility of achieving partial nitrification and biological phosphorus removal simultaneously in an SBR system.
• To identify key operational parameters for enhancing biological phosphorus removal.
• To understand the impact of low temperatures and operational conditions on partial nitrification.

Main Methods:

• Pilot-scale SBRs were operated under an anaerobic/aerobic configuration for 8 months.
• Volatile fatty acids were supplied to enhance biological phosphorus removal.
• Operational parameters like temperature, dissolved oxygen, and solid retention time (SRT) were monitored and controlled.

Main Results:

• Simultaneous biological phosphorus removal and partial nitrification were successfully achieved in the SBR.
• Sufficient volatile fatty acid supply was essential for enhanced biological phosphorus removal.
• Partial nitrification was feasible at low temperatures with high dissolved oxygen (>3 mg/L).
• Nitrite oxidizing bacteria (NOB) washout occurred due to shorter SRT, enabling partial nitrification.
• Aerobic phosphorus uptake by phosphorus accumulating organisms was sensitive to nitrite inhibition.

Conclusions:

• Partial nitrification and biological phosphorus removal can be effectively integrated into SBR systems.
• Controlling SRT is a critical strategy for achieving partial nitrification in cold climates.
• The findings support the development of cost-effective and sustainable biological nutrient removal processes.