Low cost solution to remove fluoride from groundwater

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Does anyone have a low cost safe solution to  remove Fluoride from pumped groundwater  for rural communities?


* Editors note: a similar question was asked 5 years ago and has 31 answers, but is not focused on low cost for rural communities.

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9 Answers

  1. You may wish to look into this solution.

     

  2. How much fluoride is in the water? For moderate levels children are the concern because their teeth can be fluorosed before they erupt. So, in that case providing lower fluoride water to teh children is sufficient. Adults have the risk of osteomalacia or crippling skeletal fluorosis if the daily intake is much  higher. WHO guideline is 1.5 mg/L. But that might be too high in a warm climate with high water consumption, say more than 3 or 4 liters per day.. Your national government or dental organizations should have appropriate advice as to how much fluoride is too much in your environment.

  3. The choice of cleaning method depends on the content of fluoride in water, volume of ​pumped  ​ water and other.
    I advise you to try filtering of water through filters with finely chrushed glass..

  5. As mentioned by others here, a couple of options would be inexpensive point of use reverse osmosis systems(best). Bone char and activated ​alumina (second) these products have a limited life and will become exhausted, needing replacement. Calculations based on the amount of Fluoride and estimated daily water usage will project active media life expectancy. Anion media (poor) does not have a strong affinity for Fluoride, any other anions in the water will be removed first and occupy the reception sites.

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    1. Hi Terry, 

      For low-cost removal of Fluoride you will need to compare the cost of high tech reverse osmosis systems to low-cost other treatment, like the Nalgonda technique using Aluminium Sulphate and Lime. 

      Regards, 

      Erik Thorbjorn Norremark

  6. Hi Hannah Simcoe-Read, 

    I did my MSc Thesis (1990) on " low cost ​safe solution ​to  remove ​Fluoride from ​pumped ​groundwater ​ for rural ​communities" in Tanzania. 

    There are two low-cost appropriate technologies, with

    1) household treatment using "bone char"  and

    2) Nalgonda village level treatment  (lime and aluminium sulphate precipitation of fluoride).

    Both methods only treat water for consumption (drinking, cooking).

    Bone char household filter is made with animal bones charred above 400 C to remove organics but retain the apatite crystal structure, where when applied in a filter unit the fluoride ion will substitute H+, and fluoride free water comes out of filter). The amount of bone char in the filter can be adjusted to a lifespan of 1 year, 20 L per day. The amount needed depends on initial fluoride concentration in raw water. At some stage the the fluoride front will break through the column (long pipe used for filter) and fluoride concentration in output water start to increase until the filter material is exhausted.  The charring of the bones is best done in a closed container with limited air, over long time. Then the bones are crushed to granules of 1-4 mm before put in filter. The colour of the crushed bone granules must be light grey, as darker colour indicates residual organic material (giving colour and taste to the treated water), but not white as this colour indicates a too high temperature destroying the apatite crystal structure thus eliminating the fluoride removal capacity. 

    The challenge for promoting bone char household filters in rural areas is not really technical, but socio-health related. The expecting mother needs to drink treated water to prevent the permanent teeth in the fetus to be damaged. The children need to drink treated water to reduce/eliminate development of skeletal fluorosis. Due to the long time from exposure to visible effects it is difficult to convince families to invest in the filter, annual replacement of bone char and daily operation. 

     

    The Nalgonda technique is developed in India, with lime and aluminum sulphate (Alum) using batch treatment in large tank, using paddles for stirring the water. An improved design (my design) will use the pressured water to stir the water volume, for mixing chemicals, flocculation / coagulation. Hence no need for electricity or manpower for stirring. The intensity for stirring will reduce while the tank fills up. The stirring is partly done by the water jet (horizontal rotation), partly done by air sucked into the water jet (vertical rotation). A lime water solution (CaCo2) with PH 11 is added for PH adjustment initially of raw water, while the Alum water solution with PH 4 is removing fluoride (and other stuff), while adjusting the out put water to PH 6.5 or 7. The optimal PH for coagulation is 6.5. Due to the extreme high and low PH in the dissolved concentrated chemicals this process should not be done at household level, but can be done by e.g. a women group trained in daily operation and handling of chemicals. The filter constructed outside Arusha would deliver about 1500 L treated water and 100 L sludge per day. The filter is operated in the afternoon, when empty, first cleaned for sludge then filled with raw water and chemicals and left overnight to settle. Next morning treated water can be tapped from the tank via a tap situated just above the sludge level. On a weekly basis the women group weights out portions of chemicals using a basic scale, for the proper amounts of chemicals to be applied every day by the daily operator (women taking turns during the week). - It is important to monitor the PH in the treated water on a monthly basis, as the Lime lose PH adjusting capacity during storage, and Lime dosage needs to be increased over time.  Provided there is access to the chemicals this process is very VLOM and low-cost. The raw water was about 9-10 mg/L treated down to about 2 mg/L. There is a maximum dosage of Alum, actually the sulphate, that should noticed, as excess will act as a laxative.  

    The treated water has a production cost, so it is essential that there is established some kind of sustainable user-payment to secure funds for buying chemicals in bulk, transport of chemicals, maintenance of tank, balance, small containers for daily chemical dosage. 

     

    For low-cost fluoride removal using bone char in Tanzania google: 

    Ngurdoto Defluorination Research Station,  Godfrey Mkongo

     

    Regards,

    Erik Thorbjoern Noerremark

     

     

    1 Comment

  7. Hi...Here is something to consider, but is only one perspective:  Fluoride is among the most challenging contaminants to remove. I too live in a very rural community (about 47 people) and we have fluoride issues in our groundwater. Our small town received a federal grant to commission an RO system that cost about $800k. It was installed on the town well about 10 years ago. But it is overkill and quite costly to operate for such a small community. Moreover, our community is so small that no one was trained properly to operate the system on a reliable basis. Depending on the size of your community, you may want to consider point-of-use RO devices for treating high-fluoride water. They are inexpensive and remove about 95% of the F. A typical under-the-counter RO device for the kitchen can produce ample drinking and cooking water for entire families. The 12-inch membranes in the devices are now rated at 150 GPD. The entire unit with a permeate pump to minimize brine waste costs about $350. The membranes last at least a couple of years under normal use conditions and replacement cost is about $50. One advantage of this "distributed" treatment approach is that if one or a few units happen to fail, then potable water is still available from a neighbor until the failed ones are fixed or replaced. Most people can easily install these units themselves, but it would be easy enough to also hire a plumber to do the installation. It only takes about an hour. Membrane replacement tales only about 10 minutes of fiddling around. The permeate quality is easy to monitor by anyone and can be done in a few minutes with a cheap TDS meter that can be purchased on eBay. Some RO units have this feature built in. Hope this viewpoint helps.

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  8. Good Afternoon Hannah,

    Aquathin has extensive experience with relatively low cost with ease of operation and maintenance utilizing anion or activated alumina.  Systems include outlying Kenyan villages.

    Warmest regards,

     

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