一、What is anaerobic ammonium oxidation (ANAMMOX) process?

Anaerobic Ammonia Oxidation (ANAMMOX) is a novel biological denitrification technology that utilizes specific microorganisms under anaerobic conditions to directly convert ammonia nitrogen and nitrite in wastewater into nitrogen gas. Compared with traditional nitrification denitrification processes, ANAMMOX process has significant advantages such as no need for external carbon sources, low energy consumption, and low sludge production. It is an innovative denitrification technology that has attracted much attention in the field of wastewater treatment in recent years.

二、Working principle of anaerobic ammonia oxidation process

The anaerobic ammonia oxidation process relies on the unique metabolic pathway of ANAMMOX bacteria. In anaerobic environments, these bacteria directly convert ammonia nitrogen and nitrite into nitrogen gas and a small amount of nitrate through reactions

This process does not require oxygen or organic carbon sources, and relies entirely on anaerobic environments and microbial metabolic activities. ANAMMOX bacteria usually grow slowly, but they have extremely high ammonia oxidation efficiency under anaerobic conditions and can treat high concentration ammonia nitrogen wastewater in a short period of time.

三、Process flow of anaerobic ammonia oxidation technology

The ANAMMOX process is usually combined with partial nitrification (PN) to form a PN-ANAMMOX combined process for better treatment of ammonia nitrogen wastewater. The basic process is as follows:

1. Partial Nitrification (PN) Stage: Firstly, in the partial nitrification reactor, the ammonia nitrogen in the wastewater is partially oxidized to nitrite (NO ₂⁻) through nitrification, but not completely oxidized to nitrate (NO ∝⁻). This stage is usually carried out under low oxygen conditions to control the degree of nitrification reaction.

2. Anaerobic ammonia oxidation (ANAMMOX) stage: Nitrite and residual ammonia nitrogen then enter the ANAMMOX reactor and are directly converted into nitrogen gas under anaerobic conditions through the action of ANAMMOX bacteria. The small amount of nitrate generated during the reaction process can be further processed or directly discharged.

3. Discharge of effluent: After anaerobic ammonia oxidation treatment, the concentration of ammonia nitrogen and nitrite in the water is significantly reduced. Once the water quality stabilizes and meets the standard, it can be discharged or further treated in subsequent treatment units.

4、 Advantages of Anaerobic Ammonia Oxidation Process

1. Energy saving and efficient: The anaerobic ammonia oxidation process does not require an external carbon source, and the oxygen demand is significantly reduced. The energy consumption is only about 50% of the traditional nitrification denitrification process, and nitrogen is directly released into the atmosphere, reducing sludge production.

2. Low sludge production: The bacterial metabolic products in ANAMMOX process are mainly gas, and the amount of excess sludge generated is extremely low, reducing the cost of sludge treatment and disposal.

3. Easy to operate: Due to the lack of external carbon sources and complex oxygen control, the operation of ANAMMOX process is relatively simple, easy to manage and maintain.

4. Strong adaptability: Anaerobic ammonia oxidation process is suitable for treating high concentration ammonia nitrogen wastewater, especially in some specific industrial wastewater treatment projects, showing excellent adaptability and treatment effect.

五、Application fields of anaerobic ammonia oxidation process

The anaerobic ammonia oxidation process is widely used in various wastewater treatment applications that require efficient denitrification, including:

1. Municipal sewage treatment plant: used for ammonia nitrogen removal and upgrading of municipal sewage treatment plants, significantly reducing the nitrogen content in sewage.

2. High ammonia nitrogen industrial wastewater treatment: Suitable for the treatment of high ammonia nitrogen wastewater in industries such as coking, garbage leachate, petrochemicals, and fertilizers, it can effectively remove high concentrations of ammonia nitrogen.

3. Sludge digestion liquid treatment: Used for the treatment of high ammonia nitrogen digestion liquid produced by anaerobic digestion of sludge, it is an important part of the internal circulation system of sewage treatment plants.

4. Eutrophication treatment of water bodies: Used for the removal of ammonia nitrogen from eutrophic water bodies such as lakes and rivers, controlling eutrophication problems and improving water quality.

6、 Challenges and Future Development of Anaerobic Ammonia Oxidation Process

Despite its outstanding performance in denitrification efficiency and energy consumption, the anaerobic ammonia oxidation process still faces some challenges in practical applications:

1. Cultivation and domestication of ANAMMOX bacteria: ANAMMOX bacteria grow slowly and are sensitive to environmental conditions, requiring a longer start-up and domestication process.

2. Optimization design of reactor: Due to the strict requirements of ANAMMOX bacteria for anaerobic environment, the design and optimization of operating parameters of the reactor are particularly important.

3. Process stability: How to maintain the stability of the process during long-term operation and avoid the influence of external factors (such as temperature and pH fluctuations) on ANAMMOX bacterial activity is still a problem that needs to be studied and solved.

To address these challenges, future development directions include:

1. Quick start technology: Research and develop more efficient ANAMMOX bacterial culture and domestication techniques to accelerate the reactor start-up process.

2. Intelligent control: Introduce intelligent monitoring and automated control systems to monitor the real-time operation status of the reactor, ensuring the long-term stability of the process.

3. Process combination optimization: Combine ANAMMOX process with other denitrification processes such as anaerobic ammonia oxidation partial nitrification (SNAD), membrane bioreactor (MBR), etc., to form a more efficient comprehensive denitrification treatment system.