AA(Activated Alumina) for removing fluoride
Fluorine is one of the trace elements necessary for animals and humans. The normal daily intake of adults is 2~3mg, too much or too little will bring diseases. China is one of the countries in the world where drinking water-type endemic fluorosis is the most widespread and harmful due to high levels of fluorine in drinking water.
Therefore, the removal of fluoride in drinking water is a prerequisite for safety. The removal of fluoride by activated alumina is the most common and most successful method because of its high adsorption capacity, good strength, wear resistance, long service life, stable performance, and water quality after fluoride removal. It meets sanitary standards because it is one of the indispensable water purification materials for sewage treatment.
In sewage treatment, activated alumina is a porous adsorbent, which has mechanical strength, physical and chemical stability, high temperature resistance and corrosion resistance. Especially for the treatment of fluorine-containing wastewater.
Fluorine is adsorbed on the surface of the adsorbent to generate insoluble fluoride, and the SO2 on the adsorbent can exchange other anions such as F and HCo3 in the water. The adsorbent can be placed in the filter, the thickness is generally 700~1000mm, the particle size is 0.5~2.5mm, the filtration speed is 1.5~2.5 m/n, the supporting layer is made of pebbles, the thickness is 400~700mm, and the acid is added to adjust the raw water ph to 5.5 ~6.5.
Using small particles of activated alumina (large specific surface area) can improve the effect of removing fluorine and reduce the cost of water production. When the fluoride removal capacity of the adsorbent is not up to the standard, aluminum sulfate can be prepared into a 1%~2% solution and passed through the filter column at a flow rate of 0.6 m/n for 6~8 minutes (the amount required is about 60 times the amount of fluorine removal) Regenerating it is the best technology to remove various inorganic ions such as fluoride.
