The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 27, 1991
Filed:
Sep. 24, 1990
Kurita Water Industries Ltd., Tokyo, JP;
Abstract
Dsiclosed is a method of treating fluoride-containing water, which comprises a reaction step where a calcium compound and/or an aluminium compound are/is added to 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 to be formed in the membrane-separation step of the following stage is added to the suspended liquid and stirred and the resulting suspension is introduced into the circulation tank; a membrane-separation step where the suspension from the circulation tank is treated by membrane-separation to separate it into a permeated solution and a concentrated suspension; a circulation step where at least a part of the concentrated suspension to be taken out from the membrane-separation step is returned back to the reaction step while the remaining part thereof is circulated to the circulation tank; and a step where the permeated solution is taken out from the membrane-separation step as a treated water. The method is free from scaling disorder of the apparatus used and gives a treated water of high quality stably and efficiently.