Excessive ammonia nitrogen in wastewater is a common environmental problem, which is mainly used in industrial wastewater, agricultural discharge and urban sewage. Excessive discharge of ammonia nitrogen can cause serious damage to the environment and ecosystems, so it is crucial to choose a suitable process to remove ammonia nitrogen from wastewater. In this article, we will introduce several commonly used ammonia nitrogen removal processes and analyze their advantages and disadvantages, in order to provide a useful reference for wastewater treatment.
1. Physical method to remove ammonia nitrogen.
The physical removal of ammonia nitrogen is mainly through adsorption, ion exchange and other methods to separate ammonia nitrogen from wastewater. The adsorption method is a commonly used physical treatment method, the principle of which is to use the adsorption properties of the adsorbent to adsorb the ammonia nitrogen in the wastewater to the surface of the adsorbent. Common adsorbents include activated carbon, zeolite, bentonite, etc. The advantages of adsorption method are simple operation, low investment and small footprint, but the regeneration and replacement of adsorbents need to be carried out regularly, and the treatment effect of high-concentration ammonia nitrogen wastewater is limited.
The ion exchange method is to exchange the ammonia nitrogen ions in the wastewater with other ions on the resin through the ion exchange resin, so as to achieve the removal of ammonia nitrogen. The ion exchange method has the advantage of good treatment effect and stable effluent quality, but the cost of resin regeneration and replacement is high, and the treatment effect of wastewater containing complex components may not be good.
2. Chemical removal of ammonia nitrogen.
The chemical removal of ammonia nitrogen is mainly through chemical reactions to convert ammonia nitrogen into harmless substances. Common chemical methods include chlorination, oxidation, and breakpoint chlorination. The chlorination method is to add chlorinating agents such as chlorine or sodium hypochlorite to the wastewater, so that ammonia nitrogen reacts with the chlorinating agent to produce nitrogen and water. The advantages of this method are that the reaction speed is fast and the treatment effect is good, but it may produce secondary pollution, such as chlorinated organic compounds.
The oxidation method is to oxidize ammonia nitrogen to nitrate by adding oxidants such as hydrogen peroxide, potassium permanganate, etc. to the wastewater. The advantages of this method are good treatment effect and stable effluent quality, but the cost of oxidant is high, and the treatment effect of wastewater with complex components may be affected.
Breakpoint chlorination method is a special chlorination method, the principle of which is to add an appropriate amount of chlorine or sodium hypochlorite to the wastewater, so that ammonia nitrogen reacts with chlorine to produce nitrogen and water, and after reaching a certain chlorination dose, the reaction rate of chlorine and ammonia nitrogen suddenly decreases, that is, to reach the "breakpoint". The advantages of this method are that the treatment effect is good and the reaction speed is fast, but the control of chlorination dose is critical, and excessive chlorination may lead to secondary pollution.
3. Biological removal of ammonia nitrogen.
Biological removal of ammonia nitrogen is the use of microbial metabolism to convert ammonia nitrogen into harmless substances. Common biological methods include activated sludge method, biofilm method, etc. The activated sludge method is to form activated sludge in wastewater by cultivating a large number of microorganisms, and the microorganisms use the organic matter in the wastewater as a carbon source and energy source to convert ammonia nitrogen into nitrogen. The advantages of this method are good treatment effect, stable operation and low cost, but it requires regular sludge discharge, and the treatment effect of high concentration ammonia nitrogen wastewater is limited.
The biofilm law uses microorganisms on the biofilm to convert ammonia nitrogen in wastewater into nitrogen. Biofilm can be formed by attaching to the surface of the filler, and as the wastewater passes through the filler, microorganisms grow and multiply on the biofilm and degrade the organic matter and ammonia nitrogen in the wastewater. The advantages of this method are good treatment effect, small footprint, and high resistance to shock loads, but the replacement and cleaning of the packing need to be carried out regularly.
Fourth, the comprehensive process to remove ammonia nitrogen.
In practical applications, in order to improve the removal effect of ammonia nitrogen, a comprehensive process is often used. The comprehensive process can combine the advantages of physical, chemical and biological processes according to the characteristics and treatment requirements of wastewater to achieve better treatment results. For example, suspended solids and particulate matter can be physically removed from wastewater, followed by chemical conversion of ammonia nitrogen to nitrate, and finally further conversion of nitrate to nitrogen by biological methods.
In summary, the problem of excessive ammonia nitrogen in wastewater needs to be removed by a suitable process. Physical, chemical and biological methods have their own advantages and disadvantages, and the choice of process needs to be comprehensively considered according to the characteristics and treatment requirements of wastewater. In practical application, the advantages of multiple processes can be combined, and a comprehensive process can be used to improve the removal effect of ammonia nitrogen. At the same time, in order to protect the environment and ecosystems, we also need to strengthen the supervision and management of wastewater discharge, and promote the continuous innovation and development of wastewater treatment technology.