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What Is Aeration Boosting in Aerobic Tanks?
Aeration boosting (also called “intensive aeration”) is a common strategy in biological wastewater treatment. By increasing dissolved oxygen (DO), it improves microbial activity, especially for nitrifying bacteria responsible for ammonia nitrogen removal.
However, in many cases, even after boosting aeration, ammonia nitrogen levels remain high, leaving operators frustrated. This article explores the possible causes and offers practical solutions.
Insufficient Sludge Concentration: Limited Nitrifiers
Low concentrations of activated sludge mean fewer nitrifying bacteria. In high-load conditions, the nitrification process is easily suppressed.
✅ Solution: Increase sludge concentration to raise the number of nitrifiers. Regularly monitor sludge activity and maintain a stable MLSS (Mixed Liquor Suspended Solids) to improve ammonia removal.
Sludge Aging or Over-Aeration: Weakened Activity
Over time, microbial populations may age, leading to decreased biological activity. Excessive aeration can also cause energy loss and shear stress on microorganisms.
✅ Solution: Periodically remove aged sludge and add or rejuvenate activated sludge. Optimize aeration flow to maintain proper oxygenation without overburdening the system.
Toxic Inhibitors: Heavy Metals or Harmful Compounds
Heavy metals (e.g., Cr, Cu, Ni), pesticides, and disinfectants can inhibit or kill nitrifying bacteria, leading to ammonia removal failure.
✅ Solution: Pre-treat toxic wastewater using adsorption, chemical precipitation, or neutralization to reduce harmful compounds before biological treatment.
Influent Quality: High Ammonia Load
If ammonia concentration in raw influent is too high, the nitrifying bacteria may not be able to keep up, even with sufficient oxygen.
✅ Solution: Introduce pre-treatment steps such as adsorption media, ion exchange, or pre-oxidation to reduce ammonia load before biological treatment.
Imbalanced C/N/P Ratio: Nutrient Limitations
A lack of carbon or unbalanced C:N:P ratio can hinder denitrification, which disrupts the nitrification process and reduces overall ammonia removal efficiency.
✅ Solution: Add a suitable organic carbon source (e.g., glucose, acetate) if needed. Keep the C:N:P ratio around 100:5:1 to ensure proper microbial growth and activity.
Poor Organic Degradation: High COD Levels
If influent COD is too high or contains non-biodegradable compounds, oxygen may be used up by heterotrophs before nitrifiers can act.
✅ Solution: Install pre-treatment units like biofilm reactors, carbon filters, or advanced oxidation to reduce COD before the aerobic stage.
Improper pH: A Key Nitrification Factor
Nitrification is highly sensitive to pH. If pH falls below 6.5 or rises above 8.5, bacterial activity will decline sharply.
✅ Solution: Keep pH between 7.0 and 8.5 by adding alkali (e.g., NaOH, lime) or acid (e.g., HCl) as needed. Use pH meters for continuous monitoring.
Environmental and Equipment Issues: Temperature or Malfunctions
Nitrification slows drastically at temperatures below 10°C. Equipment issues like poor aeration or blower failure also limit DO availability.
✅ Solution: Ensure aeration equipment runs smoothly. Use heating systems or insulation in cold regions to maintain optimal operating temperature (15–35°C).
Inadequate Hydraulic Retention Time (HRT)
If wastewater passes too quickly through the aerobic tank, nitrification is incomplete due to insufficient reaction time.
✅ Solution: Extend HRT or reduce flow rate to ensure nitrifying bacteria have enough time to oxidize ammonia effectively.
🔍 Summary: Troubleshooting High Ammonia in Aerobic Tanks
There are many factors that may cause ammonia levels to remain high even after aeration boosting, including:
- Low sludge concentration
- Microbial aging or toxicity
- High ammonia load or COD
- Unbalanced nutrients or improper pH
- Short HRT or equipment malfunction
✅ Integrated Solutions:
- Stabilize sludge concentration and microbial health
- Improve pre-treatment for ammonia and COD
- Ensure optimal DO, temperature, pH, and nutrient balance
- Extend retention time and maintain proper system configuration
By identifying the right cause and applying the correct strategy, you can significantly improve ammonia nitrogen removal and optimize your wastewater treatment performance.
📩 Have you faced similar issues in your system? Share your experience in the comments or contact our team for tailored solutions. Follow us for more wastewater treatment tips and technical insights! 🚀
