high TDS and high fluoride levels in boreholes
Dear RedR Experts,
A friend of mine is reviewing some water boreholes drilled and equipped in Kenya. There are common threads emerging: high TDS and high fluoride levels.
What simple treatments are available to reduce these issues please?
I have heard of slow sand filters equipped with crushed cow bones being used to reduce fluoride levels but have no details. I am also wondering how much a slow sand filter reduces TDS levels ....but have nothing to hand on that topic.
There are very many methods of reducing fluoride levels, but it would be best to stick with a proven method that is already in use in Kenya, is simple and doesn’t require chemical dosing. Searching the IRC WASH library (https://www.washdoc.info/) I found that the Catholic Diocese of Nakuru produce and re-activate bone char for fluoride removal, so that would seem to me to be the most appropriate line of enquiry (https://www.cathdnkenya.org/water.html). There is a paper on the viability of the bone char operation here:
I hope this helps.
You may want to look at the WHO document https://www.who.int/water_sanitation_health/publications/fluoride_drinking_water/en/index.html also look at the paper in Sandec News 7 (2006) at https://www.eawag.ch/forschung/sandec/publikationen/general/index_EN
Just to add TDS is by definition dissolved and capable of passing through a 2 micron filter. Pretty much anything that will go through a 2 micron filter will go straight through a slow sand filter too, so I wouldn't bank on any decrease in TDS with slow sand or bone char.
You generally need desalination for TDS removal. Blending with a low TDS source may be more economical if one is available.
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