Fluoride problem in drinking water


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It specify the effect and control measures of fluoride in drinking water.

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Fluoride problem in drinking water

  1. 1. Environment & Ecology Fluoride Problem in Drinking Water.
  2. 2. Introduction Fluoride occurs naturally in most water supplies and may be added in larger concentrations above the natural background in order to promote dental health. High levels of fluoride are known to cause health problems. Fluoride concentrations in municipal water supplies were measured using an ion-selective electrode. Fluoride was detected in 23 of the 25 samples collected, all sites reported a concentration well below EPA’s standard of 4 ppm and the WHO’s standard of 1.5 ppm. “...fluoride prevents dental caries predominately after eruption of the tooth into the mouth, and its actions primarily are topical for both adults and children…” CDC (1999). Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries. MMWR, 48(41); 933-940, October 22.
  3. 3. Problem due to excess fluoride: Dental fluorosis: Due to heavy intake of fluoride specially during the teeth development stage may result into severe damage to the teeth's, can result into disfigurement of teeth Severe: mottling with enamel pitting and/or loss Moderate: mottling but no enamel pitting or loss Mild fluorosis Severe fluorosis
  4. 4. Problem due to excess fluoride: Skeletal fluorosis: is a bone disease caused by excessive consumption of fluoride. In advanced cases, skeletal fluorosis causes pain and damage to bones and joints. The fluoride begins to push away and replace the other nutrients that make up bone, such as calcium.Skeletal Fluorosis is found to be most widespread in India and China, the two largest countries. skeletal fluorosis is unfortunately affecting millions of people. The World Health Organization, or WHO, has made recent estimates that about 2.7 million people in China are affected by the crippling illness. In India, about half of its states (seventeen) are considered endemic areas, or regions where a particular disease occurs often
  5. 5. Method of removal of fluoride from water. 1 . Distillation Distillation is capable of removing just about anything (except volatile compounds) from water. If you have a distiller, you can remove fluoride. The obvious drawback to distillation is that the process is time and energy consumptive and that it requires about 5 gallons of water to produce 1 gallon of distilled water. Distillation also leaves the resulting water empty and lifeless. If you use distilled water you need to add minerals (salts) back to the water. 2. Reverse Osmosis Reverse osmosis (RO) represents a reverse of normal osmotic processes. It relies on pressure and a semi-permeable membrane to remove contaminants from water. RO can remove between 90 and 95% of fluoride (depending on the efficiency of the system and depending on how well the system is maintained). Contaminants are trapped by the RO membrane and flushed away in the waste water. The process requires between 2 and 4 gallons of water to produce 1 gallon of RO water (depending on the quality of the water and the efficiency of the RO unit). Source water with an abundance of contaminants (including hard water) can reduce the efficiency of an RO system and it can shorten the life of the membrane. Similar to distillation, RO has a good track record for removing almost everything from water.
  6. 6. 3. Activated alumin Fluoride is strongly attracted to activated alumina (corundum/aluminum oxide) which has a large surface area with a huge array of tunnel-like pores. For this reason, activated alumina is the most commonly used fluoride removal media today. When used properly, it can remove up to 98% of the fluoride in water while also removing arsenic. The challenges with activated alumina are many. First of all, since the process works by ion exchange, the water must remain in contact with the media for an extended period of time—long enough for the fluoride to be adsorbed by the media. When the flow rate is faster than ¼ gallon/minute, there is not enough time to adsorb all the fluoride in the water. Another difficulty with activated alumina is that the media becomes saturated with fluoride. Depending on the amount of media in the system (how large the filter is) and on the amount of fluoride in the water, systems using activated alumina either need to be recharged or replaced often. The last difficulty with activated alumina is that aluminum is released into the treated water. This effectively trades one problem for another. Some systems address this; others do not.
  7. 7. 4. BC-Carbon Bone-Char (BC) Carbon has been used for centuries to remove naturally- occurring fluoride from water. It works similar to the way bones in the human body attract fluoride. Bone contains a porous matrix that is rich in surface ions. These can be readily replaced by fluoride and by some of the other contaminants that arrive along with fluoride (heavy metals). Bone char effectively removes a number of contaminants. When used alone, BC-Carbon can remove up to 90% of the fluoride in water. The efficiency of bone char can be improved by adding pre-filters that remove heavy metals and other contaminants before exposure to the BC-carbon. Bone char works best at a slightly acidic pH and may not work as well with hard water.