high conc fluoride removal
high conc fluoride removal
(OP)
I need to remove 500-1000ppm Fluoride from a waste stream with a flowrate of 50,000gpd down to 4.5ppm, pH is 2. One suggestion was lime or RO. Are these the best options which will have minimal waste to dispose of?





RE: high conc fluoride removal
RE: high conc fluoride removal
You probably have other things in that analyses that you are not telling us about that would most likely foul an RO.
RE: high conc fluoride removal
If you are going to discharge the water then you will have to get the pH up into the 6-9 range so the lime precipitation may be cost effective.
If the water chemistry is suitable for RO what are you going to do with the concentrate stream? The F concentration will be higher but you will have a smaller volume to deal with. You are going to need to raise the pH to protect the membranes.
If you are considering evaporation be careful as F attacks Ti.
RE: high conc fluoride removal
RE: high conc fluoride removal
RE: high conc fluoride removal
Traditionally, neutralisation of fluoride-containing wastewater with lime is used. But frequently, the amount of lime required for neutralisation is insufficient for adequate fluoride removal. Furthermore, the separation of calcium fluoride from the wastewater is difficult and huge quantities of sludge are produced that might also contain other compounds in high concentrations. This bulky sludge often has to be disposed of as chemical waste.
Fluoride removal by crystallisation in a fluidised bed achieves effluent concentrations down to 5 (or even 2 mg/l with an additional filtration unit) in one reactor. The high upflow velocity of 40 to 75 m/h through the reactor results in a small footprint. The product is calcium fluoride pellets that are compact and virtually water free. They do not have to be landfilled but can be sold as a fluoride resource.
This technology is used for wastewater treatment or for removal of fluoride from water loops (reuse of water). When you search under the name " Crystalactor " you will probably find a supplier for this technology.
So FredE: The fluoride effluent concentration fits with your demand, the "waste" becomes a resource, the footprint is small and the technology is proven. I trust this has helped you
Jacco