What are the main technologies for treating ammonia nitrogen wastewater?

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This post was last edited by O.K. on 2016-4-19 at 22:38. The main technologies currently used for treating ammonia nitrogen wastewater include: biological denitrification, stripping and distillation methods, breakpoint chlorination, ion exchange, chemical precipitation, catalytic wet oxidation, electrodialysis, liquid membrane processes, and electrolysis methods. 1. Biological nitrogen removal: In the biological treatment of wastewater for nitrogen removal, first, under aerobic conditions, ammonia nitrogen in the wastewater is oxidized to nitrite or nitrate through the action of aerobic nitrifying bacteria. Then, under anaerobic conditions, denitrifying bacteria reduce nitrite and nitrate to nitrogen gas, which is released from the wastewater. It is difficult to use conventional biological treatment for wastewater containing high concentrations of ammonia nitrogen. On the one hand, in order to allow microorganisms to grow properly, it is necessary to increase the recirculation ratio in order to dilute the original wastewater. On the other hand, not only is a large amount of oxygen required during the nitrification process, but a substantial amount of carbon source is also needed for denitrification; generally, a COD/TKN ratio of at least 9 is considered necessary. 2. Stripping and stripping methods: In both the stripping and stripping methods, the pH of the wastewater is adjusted to an alkaline level, causing the ionic form of ammonia to be converted into molecular ammonia. Then, the waste gas is brought into contact with this ammonia, enabling the transfer of ammonia nitrogen from the liquid phase to the gas phase. This method is commonly used in the treatment of wastewater with high concentrations of ammonia nitrogen. However, in practical operation, there are issues such as low processing efficiency, scale formation that affects operations, high energy consumption and maintenance requirements, as well as a tendency to cause secondary pollution. 3. Breakpoint chlorination: This method involves introducing chlorine gas into wastewater until a certain point is reached; at this point, the concentration of free chlorine in the water is at its lowest, while the ammonia concentration drops to zero. The treatment efficiency of the chlorination method reaches 90%–100%, but it has high operating costs, and the by-products chloramine and chlorinated organic compounds cause secondary pollution. The chlorination method is only suitable for treating wastewater with low concentrations of ammonia nitrogen. 4. Ion exchange method: This method uses zeolites with high selectivity for specific ions as exchange resins, thereby achieving the removal of ammonia nitrogen. The ion exchange method is suitable for the treatment of ammonia nitrogen wastewater at medium and low concentrations