Selective fluoride and ammonia removal by chromatographic separation of wastewater
A process for fluoride removal from wastewater streams produced during industrial operation for further industrial use or to comply with environmental regulations. The process segregates the removal of fluoride and fluorosilicate ions, from the totality of ions in the waste water stream, thus improving treatment efficiency and reducing costs. Ion-exchange chromatography is used to remove the fluoride and fluorosilicate ions by passing the wastewater stream through one or more columns that contain a charged resin which selectively binds cations/anions in the stream. The fluoride ions are washed from the column and then collected for removal or use in other processes.
1 . A process for treating a wastewater stream including removing substantially all fluoride ions contained in the waste water stream, comprising:
a. exchanging hydrogen ions in a strong acid cation resin containing hydrogen ions with aluminum ions by passing a solution of aluminum salt through the strong acid cation resin;
b. rinsing the strong acid cation resin with water;
c. removing hydrofluoric acid from the wastewater stream by passing the wastewater stream through the aluminum ion exchanged strong acid cation resin.
2 . The process of claim 1 wherein the aluminum salt is at least one of aluminum chloride or aluminum sulfate and the corresponding acids are hydrogen chloride or hydrogen sulfate respectively.
3 . The process of claim 1 further comprising collecting the total runoff from said exchanging and rinsing in a tank.
4 . The process of claim 1 further comprising adding the mixture of mineral acid and total runoff from said exchanging and rinsing to the strong acid cation resin.
5 . The process of claim 1 further comprising monitoring the wastewater stream passing through the strong acid anion resin to test for fluoride breakthrough.
6 . The process of claim 1 further comprising regenerating the strong acid cation resin by passing through the strong acid cation resin, a concentrated mineral acid corresponding to the aluminum salt passed through the strong acid cation resin.