There are various treatment methods for high-concentration ammonia nitrogen wastewater, including physical, chemical and biological methods, each method has its own characteristics and advantages and disadvantages, and it is necessary to choose the appropriate method according to the characteristics of wastewater and treatment needs in practical application to ensure the treatment effect and economic benefits.
Case study of ammonia nitrogen wastewater treatment
Case 1: Pharmaceutical wastewater treatment practiceThe concentration of ammonia nitrogen wastewater discharged by a pharmaceutical company in its daily production is as high as an astonishing 2000mg/L, far exceeding the national discharge standard. In order to solve this problem, the company adopts the "two-stage blowing off method".
First, the pH of the wastewater is raised to an alkaline level through precise chemical adjustment, a step that is essential for the removal of ammonia nitrogen.
Subsequently, a large amount of air is introduced through the blow-off tower, which detachs the ammonia nitrogen from the wastewater in a gaseous form. After this series of treatments, the ammonia nitrogen concentration was successfully reduced to below 120mg/L, which met the national emission standard.
In addition, the ammonia released during the blow-off process can be converted into valuable chemicals through further treatment and recycling.
Case 2: Wastewater treatment of fertilizer plantAmmonia nitrogen wastewater produced in the production process of a large fertilizer plant contains a large amount of organic matter and suspended solids, and the concentration of ammonia nitrogen is also extremely high. To treat this complex wastewater, the plant uses an A/O (anaerobic/aerobic) biological treatment process.
In this process, the wastewater first comes into contact with microorganisms in an anaerobic reactor, the organic matter is broken down, and ammonia nitrogen is converted into ammonia.
Subsequently, the wastewater enters the aerobic reactor and the ammonia nitrogen is further converted into nitrate and nitrite under the action of microorganisms. For advanced treatment, the plant also incorporates ion exchange or chemical precipitation to completely remove ammonia nitrogen by adding specific chemicals, such as magnesium ammonium phosphate (MAP), to form an insoluble precipitate. In the end, the concentration of ammonia nitrogen in the wastewater was significantly reduced, and the indicators such as COD and suspended solids also met the discharge standards.
Overview of ammonia nitrogen wastewater treatment technology
Physical method: Blowing technology uses air or steam to blow ammonia nitrogen by adjusting the pH value of wastewater. This process usually takes place in a blow-off column, where the column is filled with a water film, air is blown in from the top, ammonia nitrogen is detached from the surface of the water film, and as the air rises to the top of the tower, ammonia nitrogen is collected and further processed.
Chemical methods: Chemical precipitation techniques include chemical precipitation methods (such as MAP methods), in which ammonia nitrogen is removed by adding chemicals, such as magnesium ammonium phosphate, to generate insoluble precipitates. This method is particularly effective when treating wastewater with high levels of organic matter.
Biological method: Biological treatment technology uses the nitrification and denitrification of microorganisms to convert ammonia nitrogen into nitrogen. This process is usually done in the A/O process, where the microorganisms decompose the organic matter in the anaerobic phase and produce ammonia at the same time; In the aerobic phase, ammonia nitrogen is further converted to nitrate and nitrite, and finally to nitrogen in the denitrification phase.
Analysis of the advantages and disadvantages of ammonia nitrogen wastewater treatment technology
The blow-off method is simple to operate and has high removal efficiency, but it requires a large amount of air or steam, and may produce secondary pollution, such as ammonia that is not completely removed.
Chemical precipitation is effective, but it produces large amounts of sediment that require additional treatment steps to treat these sediments, increasing treatment costs.
The biological method has no secondary pollution, the treatment process is relatively slow, and it requires a long residence time, but the operating cost is low, and it is suitable for long-term stable operation.
In summary, there are various treatment methods for high-concentration ammonia nitrogen wastewater, and each method has its applicable scenarios and limitations. In practical application, the most appropriate treatment strategy should be selected according to the specific characteristics and treatment requirements of wastewater, taking into account technical, economic and environmental factors.