NEWDEF ®Hydroxyapatite – Fluoride removal

NEWDEF ®Hydroxyapatite – Fluoride removal

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NEWDEF® Hydroxyapatite is rapidly becoming the media of choice for removing fluoride from potable and waste water. The media is aluminium  III activated .   This media can also be used for fluoride removal in waste water including  the aluminium finishing waste waters that use fluoride containing chemicals.

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NEWDEF ®Hydroxyapatite – Fluoride removal

Hydroxylapatite, also called hydroxyapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. Hydroxylapatite is the hydroxylendmember of the complex apatite group. The OH ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonalcrystal system. Pure hydroxylapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colourations, comparable to the discolourations of dental fluorosis.  

Source: Wikipedia.

It is one of the most effective adsorbents of fluoride  with much faster reaction times than Activated Alumina.

1.   Defluoridation Capacity

The defluoridation capacity of hydroxapatite  is about 2~4 mg/g which is superior   compared to most medias  under  the same conditions. The capacity is impacted  by different raw water quality including fluoride concentration、 temperature、co-existing ions etc..



   Hydroxyapatite  Features and Benefits

  • High capacity and shorter contact time
  • Very safe to use; no dissolution of toxic and hazardous substances
  • High efficiency,  hydroxyapatite can remove  up to 99% fluoride  in raw water.
  • Limited competing interference  by other  ions
  • Lower regeneration cost and simple regeneration process
  • Not only restricted to Fluoride ,but can remove iron and manganese as well

Performance Comparison

Fig below demonstrates that the NEWDEF® media( Hydroxapatite)  outperforms  other common defluoridation materials under the same conditions. The treated water volume before fluoride breakthrough  of NEWDEF® is About 5.09—11.7 times of activated alumina and 12.9—23 times of activated clinoptilolite.

Figure 1The volume of water treated by different medias under the same conditions, the  initial concentration of fluoride is 6mg/L in raw water

Figure 2.  The volume of water treated by different media under the same conditions, the concentration of fluoride is 2mg/L in raw water

Sodium hydroxide regeneration: It’s the reverse  reaction of the  defluoridation mechanism. OH replaces F on the  particle surface.   Regeneration is carried out using 0.5 to 1 % caustic solution which is recirculated for 6-12 hours.