Fluoride is widely present in nature. The fluoride content in natural water is generally between 0.3~0.5mg/L. The groundwater flowing through fluorine-containing ore layers can sometimes reach up to 2-5 mg/L. The distribution range of fluoride in groundwater in China is very wide. In many areas, the fluoride content in groundwater exceeds the national standard for fluoride content in drinking water, and some areas even reach up to 20mg/L. For residents in water consuming areas, long-term consumption of high fluoride water can cause chronic poisoning, especially serious harm to teeth and bones. Mild cases of dental fluorosis can manifest as enamel damage, premature tooth loss, and other symptoms. Severe cases can cause bone and joint pain, even bone deformation, hunchback, and complete loss of labor ability. Therefore, the harm of high fluoride water is very serious, and it is very important to use groundwater defluorination equipment and deep well water defluorination equipment to treat groundwater and deep well high fluoride water.

Groundwater defluorination equipment often uses adsorption filtration method. When the raw water flows through the core filter layer of the defluorination filter - natural mineral filter material, the water comes into contact with the natural mineral filter material in the defluorination filter. Through physical and chemical reactions - adsorption, fluorine is adsorbed on the surface of the adsorbent, generating insoluble fluoride, so that the fluoride content in the water reaches within 1.0 mg/L as stipulated in the national drinking water hygiene standard (GB5749-2006). When the defluorination ability drops to a certain limit (saturation), the adsorbent's defluorination ability is restored through regeneration with a rejuvenator.
The groundwater defluorination equipment and deep well water defluorination device (defluorination filter) produced by Ruizhi Environmental Protection Company have introduced new technologies, processes, and devices, which can effectively solve the above problems and keep the population in areas with excessive fluoride content away from the harm of high fluoride.
The groundwater defluorination device consists of defluorination filters, filter materials, regeneration devices, pipeline valves, etc. Different sizes of defluorination filter equipment can be selected according to different fluoride content and treatment water volume. The size of the defluorination filter depends on the water volume, and steel or fiberglass can be selected according to different purposes. The defluorination device has a fixed bed and a fluidized bed. The water flow in a fixed bed is generally upflow, with a filter layer thickness of 1.1-1.5m and a filtration rate of 3-6m/h. The thickness of the moving bed filter layer is 1.8-2.4m, and the filtration rate is 10-12m/h.
The groundwater defluorination equipment and deep well water defluorination device use special activated alumina as the defluorination adsorbent. The defluorination process is combined with acid or pH adjustment of raw water and adsorption catalysis to obtain high adsorption performance for fluoride. The groundwater defluorination device uses aluminum sulfate or sodium hydroxide as regenerants and adopts high flow circulation regeneration for rapid neutralization. It can maximize the recovery of the adsorption performance of activated alumina, thereby achieving continuous defluorination process. The adsorbent adopts a cyclic regeneration method, using aluminum sulfate or sodium hydroxide solution with a concentration of 1% -2% as the regeneration agent, and the filter material can be reused. The deep well water defluorination filter is a new type of defluorination equipment different from the deionization method (electrodialysis, reverse osmosis).
Principle and process flow of groundwater defluorination equipment
Fluorinated water passes through the activated alumina adsorption filter layer with a larger specific surface area inside the defluorination filter. Under the condition of pH 5-6, fluoride ions in water are adsorbed to form insoluble fluorides and removed. The reaction equation is as follows: R2SO4+2F -=R2F2+SO42-
After the adsorbent of the groundwater defluorination device fails, it is regenerated with aluminum sulfate solution to restore its adsorption capacity. The ratio of its dosage to defluorination is 60:1, with a regeneration concentration of 1% -2%. After running for 3-4 months, it is cleaned once with a 3.5% HCL solution. After cleaning, defluorination water can be used for rinsing for 8-10 minutes. When the pH value of the raw water is greater than 7, carbon dioxide gas is generally used for adjustment. Therefore, the use and regeneration of deep well water defluorination equipment are very convenient and cost-effective.
Functional characteristics of groundwater defluorination equipment
1. Using specially activated activated alumina as an adsorbent, it has the characteristics of fast adsorption speed, large adsorption capacity, little influence by pH value, and easy desorption. Its performance is superior to conventional activated alumina.
2. The regeneration agent replaces traditional aluminum sulfate with sodium hydroxide, eliminating the harm caused by excessive aluminum ions in the effluent to the human body.
3. The groundwater defluorination device adopts the cycle regeneration method, which can shorten the traditional regeneration time to within 4 hours.
4. By adjusting the pH value and using catalytic adsorption technology, the adsorption capacity is significantly increased.
5. Quantitative continuous addition of catalyst to increase the adsorption rate of fluorine.
6. Thoroughly solved the "compaction" problem and "false fatigue" phenomenon of activated alumina.
Main technical parameters of groundwater defluorination equipment:
1. Work pressure: 0.05Mpa~0.6Mpa
2. Working temperature: 5 ℃~40 ℃
3. Operation mode: manual or automatic control
4. Filtration speed: 2.5m/h
5. Cylinder material: 304, 316L, Q235, fiberglass reinforced plastic
Process characteristics of defluorination filter
1. Low cost and low investment;
2. Low operating costs and low water production costs;
3. The groundwater defluorination device is easy to operate: it can be operated automatically or semi automatically without adjusting the pH value;
4. The installation and use of deep well water defluorination equipment are very convenient. The deep well water defluorination equipment can be directly connected to the variable frequency pump in the deep well, and the equipment's effluent can enter the pipe network directly, without the need for a raw water tank and an effluent tank, and without the need for secondary pressurization;
5. The groundwater defluorination device has a high water utilization rate;
6. The equipment of deep well water defluorination device occupies a small area.