Comparison of domestic defluorination processes

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Advantages and disadvantages of defluorination methods: The anion resin ion exchange method requires a large amount of energy to remove anions from water. 1. The fluoride removal rate is very low; regeneration is extremely complex and difficult to manage. 3. It is hard to achieve levels below 1, and stable operation is difficult. The activated carbon adsorption method utilizes activated carbon, which has a very large specific surface area and high adsorption capacity. It cannot be regenerated, and once it becomes saturated with adsorbates, it must be discarded. High operating costs are generally unacceptable. It cannot achieve in-depth treatment. The activated alumina adsorption method: Before the 21st century, activated alumina was considered the most effective method for reducing fluoride levels. 1. Its continuous operation time is short, making it prone to false fatigue. 2. It requires acid or base to adjust the pH of the incoming and outgoing water in order to function properly. 3. The filter media is prone to caking, which leads to uneven water distribution and collection; its typical service life is 2 years. 4. It is sensitive to phosphate in water, as phosphorus binds very tightly with aluminum and cannot be removed. Once the surface area of the high-efficiency silico-aluminate natural filter media is occupied by phosphates, its ability to remove fluoride is lost. 5. There is a risk of excessive aluminum ions in the treated water; long-term consumption of water with aluminum ion levels exceeding 0.075 mg/L can cause brain aging and lead to conditions such as dementia and strokes. 6. The regeneration process is time-consuming and complex. The bone carbon (calcium hydroxyposphate) adsorption method has a high capacity for fluoride absorption. 1. The material is expensive. 2. It has poor strength and is prone to breaking. 3. Operation is complex, and management is very difficult; improper control of the concentration of the regeneration solution can result in the material breaking down and becoming ineffective. 4. The treated water has an unpleasant odor, poor taste, and there is a high risk of excessive ammonia nitrogen levels. The high-efficiency silico-aluminate natural filter media method offers: 1. A large adsorption capacity. 2. Thorough fluoride removal, resulting in high-quality treated water. 3. A simple regeneration process and easy management. 4. The filter media never suffers from caking. 5. There is no risk of excessive aluminum ions in the treated water. 6. A long service life for the filter media. It cannot simultaneously treat water containing iron, manganese, and fluoride all at once; to treat such water, iron and manganese must first be reduced to levels within the standards set by the GB5749-2006 standard for potable water before fluoride removal can take place. Electrodialysis achieves thorough fluoride removal, produces water of high quality, can be operated automatically, and is easy to manage. 1. High investment costs, 2. extremely high operating costs, 3. inability to maintain stable operation at levels below 1. The reverse osmosis method is more effective in removing fluoride than electrodialysis, produces water of higher quality, allows for automated operation, and is easier to manage. 1. High investment costs; 2. Excessively high operating costs. 3. Low average water production rate – one ton of water must be discarded for every ton of water purified. Special chelating resins can selectively remove fluoride in a thorough manner, can be operated automatically, are easy to manage, tolerate high salt concentrations, require very little amount, occupy less space, have a long lifespan, result in extremely low operating costs, require short regeneration times, and can operate stably at levels below 1. There are successful applications in industrial wastewater treatment, they offer a large adsorption capacity, and the output water does not contain excessive levels of aluminum ions. There are requirements regarding the inlet water; if no membrane process is used at the upstream stage and only calcium salt precipitation takes place, a filtration system is necessary