Part 6: **Optimizing Oxygen Levels and Ammonia Concentrations in Aeration Tanks for Activated Sludge Treatment**To optimize the treatment proces...
Published on by Hossein Ataei Far, Deputy Manager of the Research, Technology Development, and Industry Relations Center at NWWEC
To optimize the treatment process in an aeration tank, it is essential to establish specific, continuously monitored, and controlled parameters for oxygen levels and ammonia concentrations.
#### **1. Oxygen Management through Aeration** 🌬️
- **Dissolved Oxygen (DO) Setpoints:**
- 🔹 **Optimal Range:** Maintain DO levels between 1.5-2.0 mg/L to support efficient microbial activity and nitrification.
- 🔹 **Critical Limits:** Avoid DO levels below 0.5 mg/L to prevent oxygen limitation and above 3.0 mg/L to conserve energy.
- **Monitoring and Control:**
- 🔹 Utilize real-time DO sensors and automated systems like PID controllers for dynamic aeration adjustments based on demand.
- **Aeration Intensity and Energy Efficiency:**
- 🔹 Set air flow rates based on oxygen demand, and employ Variable Frequency Drives (VFDs) to optimize energy consumption.
#### **2. Ammonia Concentration Control** 💧
- **Target Ammonia Levels:**
- 🔹 Maintain effluent ammonia concentrations between 0.5-2.0 mg/L for effective nitrification.
- **Ammonia-Based Control:**
- 🔹 Utilize online ammonia sensors to make real-time adjustments to aeration intensity based on ammonia concentrations.
- **Nitrification Considerations:**
- 🔹 Ensure sufficient DO levels (above 1.0 mg/L) and maintain optimal conditions, including temperature (20-30°C) and pH (6.5-8.0), to support effective ammonia conversion.
#### **3. Integrated Control Strategies** 🔄
- **Ammonia-Based Aeration Control (ABAC):**
- 🔹 Integrate ammonia and DO data to dynamically optimize aeration intensity.
- **Model Predictive Control (MPC):**
- 🔹 Implement advanced MPC systems to make preemptive adjustments to aeration, thereby enhancing overall efficiency and performance.
#### **4. Implementation and Monitoring** 📊
- **Data Logging and Analysis:**
- 🔹 Continuously log and analyze DO and ammonia data to fine-tune aeration strategies.
- **Regular Calibration:**
- 🔹 Regularly calibrate sensors to ensure accuracy in monitoring and control systems.
**References:**
1. Ohio EPA, Activated Sludge Process Control and Troubleshooting Chart Methodology.
2. Metcalf & Eddy, Inc. (2013). *Wastewater Engineering: Treatment and Resource Recovery*.
3. Rieger et al. (2012). "Advanced control of aeration in wastewater treatment plants," *Water Science & Technology*.
4. Tchobanoglous et al. (2014). *Wastewater Engineering: Treatment and Resource Recovery*.