METHOD OF TREATING FLUORIDE-CONTAINING WATER

摘要

Disclosed is a method of treating a fluoride-containing water, which comprises a reaction step (1) where a calcium compound and/or an aluminium compound are/is added to a fluoride-containing water while the pH value of the resulting suspended liquid is adjusted to fall within the range of from 6 to 8, and at least a part of the concentrated suspension (16) to be formed in the membrane-separation step (3) of the following stage is added to the suspended liquid and stirred and the resulting suspension is introduced into the circulation tank (2); a membrane-separation step (3) where the suspension from the circulation tank is treated by membrane-separation to separate it into a permeated solution (19) and a concentrated suspension; a circulation step (15) where at least a part of the concentrated suspension to be taken out from the membrane-separation step (3) is returned back to the said reaction step (1) while the remaining part thereof is circulated to the said circulation tank (2); and a step where the said permeated solution is taken out from the said membrane-separation step as a treated water (19). The method is free from scaling disorder of the apparatus used and gives a treated water of high quality stably and efficiently.