Improved nutrient removal using in situ continuous on-line sensors with short response time

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Process Control

Background:

• Wastewater treatment plants increasingly utilize in-situ nutrient sensors within activated sludge processes.
• Traditional sensor placement in effluent streams results in significant signal delays (4-12 hours) due to sedimentation processes.

Purpose of the Study:

• To demonstrate the benefits of in-situ nutrient sensor placement for enhanced automatic process control.
• To evaluate the impact of reduced response times on nutrient removal efficiency and operational costs.

Main Methods:

• Implementation of in-situ nutrient sensors for real-time monitoring within activated sludge systems.
• Application of simple control structures and PID controllers for managing nitrogen and phosphorus removal.
• Validation through full-scale plant experiments and process simulations.

Main Results:

• Significant reductions in energy and chemical consumption for aeration, recirculation, and precipitation.
• Improved stability and reduced variations in effluent concentrations of ammonium, total nitrogen, and phosphate.
• Demonstrated effectiveness of in-situ sensing for optimizing pre-denitrification and post-precipitation systems.

Conclusions:

• In-situ nutrient sensing offers a substantial advantage over traditional methods by minimizing response times.
• Automated process control using in-situ sensors leads to more efficient and cost-effective wastewater treatment.
• The study validates simple control strategies for enhanced nutrient removal in full-scale applications.