Health Effects
Due to the natural affinity of Fluoride ions for Calcium, there is a complex interaction between ingested Fluoride and skeletal components. Fluoride in drinking water between 6 – 8 mg / L has been reported to cause Skeletal Fluorosis (brittling of bones and stiffening of joints), while concentrations in excess of 2 mg / L have been implicated (see above) in causing Dental Fluorosis, especially in children during their formative years. The generally accepted (U.S. Public Health Service) “Reference Dose” (RfD), defined as the amount that would not result in any appreciable deleterious health effect over a lifetime, is 0.06 milligrams per kilogram body weight per day.
Reduction of Fluoride
In order to prevent adverse health, or cosmetic, effects it is desirable to control the concentration of Fluoride in potable water supplies as close to the optimum level as possible. The optimum level of Fluoride in potable water is one half of the MCL of 4 mg / L., i.e. the optimum concentration is 2 mg / L. In supplies where the Fluoride exceeds the MCL, steps must be taken to reduce that level to below the MCL, and preferably to the optimum level. The remainder of this bulletin addresses the removal of excess Fluoride by various unit operations.
The Pureflow Fluoride Removal Process
The Pureflow fluoride removal process includes a unique, highly porous activated alumina media that is physically and chemically stable. It has large surface areas and a high porosity that makes it an excellent adsorbent. The media is chemically inert to all but the most corrosive gases and liquids, and resists abrasion and disintegration.
Well water containing fluoride is chemically pretreated to adjust the pH. At the optimum fluoride removal pH, some organic molecules and some trace heavy metals, including arsenic, are adsorbed on the media.
Automatic pH control ensures optimum chemical pretreatment. Fluoride ions are attracted and held to vast surface areas throughout the pores of the activated alumina, and fluoride removal is achieved.
When the activated alumina bed has removed the maximum amount of fluoride, it requires regeneration to remove the fluoride from the media. The bed is backwashed to remove suspended solids. Next, the bed is treated with caustic solution to dissolve fluoride from the media. The bed is then flushed with raw water to remove excess caustic solution and neutralize the bed.
- ASME code pressure vessels up to 250 psi
- Chemical pretreatment equipment
- Process analyzers with transmitters
- Filter face piping
- Electrically operated butterfly valves
- Filter and backwash flow meters
- Filter flow control valves
- Automatic control panel (PLC Based)
- NSF approved interior coating
- Regeneration chemical treatment equipment
- Manways, plus hatchway when required
- Up to 4″ valved drain on each filter
- Air relief valves