Process for removing perchlorate ions from water streams

• US 20060144780A1
• Filed: 09/01/2005
• Published: 07/06/2006
• Est. Priority Date: 09/01/2004
• Status: Active Grant

• Current Assignee: Envirogen Technologies Incorporated (The Envirogen Group SA)
• Original Assignee: Basin Water, Inc.
• Inventors: Jensen, Peter L., Zitlau, John, Zinn, Bryan
• Granted Patent: US 7,309,436 B2
• Time in Patent Office: Days
• US Class Current: 210/435
• CPC Class Codes: B01J 2220/606 parallel disposed columns
• CPC Class Codes: B01J 41/04 Processes using organic exchangers
• CPC Class Codes: B01J 47/00 Ion-exchange processes in general; Apparatus therefor ion-exchange chromatography processes or apparatus B01D15/08
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 2001/422 using anionic exchangers

Abstract

Methods and systems for removing perchlorate from water are disclosed. They involve: Methods and systems for removing perchlorate from water are disclosed which involve the use of a plurality of vessels containing an ion exchange resin having affinity for perchlorate ions, and in which perchlorate-contaminated water is passed over the resin in some but not all of the plurality of vessels operating in parallel to one another thereby removing perchlorate ion from the water stream and generating reduced perchlorate content product water streams and in which a subset of the plurality of vessels is removed from service, their resin is removed and replaced and they are returned to service.

Claims

1. A method for removing perchlorate ion contamination from a perchlorate-ion-contaminated water stream comprising:

a. obtaining a plurality of at least about 6 vessels each substantially filled with an ion exchange resin having affinity for perchlorate ions,

b. feeding said perchlorate-contaminated water over the resin in a substantial proportion but not all of the plurality of vessels, said substantial proportion of vessels operating in parallel to one another thereby removing perchlorate ion from the water stream and generating reduced perchlorate content product water streams and loading the resin beds in the substantial proportion of the plurality of vessels with perchlorate ions,

c. periodically removing from service a subset of the substantial proportion of the plurality of vessels containing resin that has been loaded with perchlorate in step b and replacing this subset with a similar subset of vessels taken from those vessels not employed in step b,

d. replacing the vessels removed from service in step c in the plurality of vessels with a substantially equivalent number of equivalent vessels having fresh ion exchange resin or replacing the ion exchange resin in the vessels removed from service in step c with fresh resin and returning the vessels with the replaced resin into the plurality of vessels and

e. thereafter continuing step b while periodically repeating steps c and d at least until all of the substantial plurality of vessels have been removed and replaced.

2. The method of claim 1 wherein the periodic removal from service of vessels is carried out on a predetermined schedule.

3. The method of claim 1 wherein the perchlorate content of the reduced perchlorate content product water stream is monitored and the removal from service of vessels in step c is based upon the results of the monitoring.

4. The method of claim 1 wherein the plurality of vessels is from about 6 vessels to about 30 vessels.

5. The method of claim 4 wherein the plurality of vessels is from about 10 to about 30 vessels.

6. The method of claim 5 wherein the substantial proportion of the plurality of vessels is such that no single vessel is being fed more than about 20% or the total amount of perchlorate ion-contaminated water.

7. The method of claim 1 wherein in step c the vessels removed from service are replaced with a substantially equivalent number of equivalent vessels having fresh ion exchange resin.

8. The method of claim 1 wherein in step c the vessels removed from service have their ion exchange resin replaced with fresh resin.

9. The method of claim 1 wherein the resin is a disposable ion exchange resin.

10. The method of claim 9 wherein the disposable ion exchange resin is a polystyrene-based ion exchange resin.

11. The method of claim 1 wherein the streams of reduced perchlorate content product water are pooled.

12. The method of claim 11 wherein the poled product water is passed over a polishing bed of ion exchange resin.

13. The method of claim 1 wherein the perchlorate ion-contaminated feed water is passed through a pretreatment step before being contacted with the resin beds.

14. The method of claim 1 wherein the perchlorate-contaminated water stream is ground water.

15. The method of claim 1 wherein the perchlorate-contaminated water stream is drinking water.

16. The method of claim 1 wherein the perchlorate-contaminated water stream is a brine.

17. A system for removing perchlorate ion from perchlorate ion-contaminated water stream comprising:

a plurality of at least about 6 vessels each substantially filled with an ion exchange resin having affinity for perchlorate ions,

means for feeding said perchlorate-contaminated water over the resin in a substantial proportion but not all of the plurality of vessels, said substantial proportion of vessels operating in parallel to one another thereby removing perchlorate ion from the water stream and generating reduced perchlorate content product water streams and loading the resin beds in the substantial proportion of the plurality of vessels with perchlorate ions,

means for periodically removing from service a subset of the substantial proportion of the plurality of vessels containing resin that has been loaded with perchlorate and replacing this subset with a similar subset of vessels taken from those vessels not already employed,

means for replacing the vessels removed from service in the plurality of vessels with a substantially equivalent number of equivalent vessels having fresh ion exchange resin or means for replacing the ion exchange resin in the vessels removed from service with fresh resin and returning the vessels with the replaced resin into the plurality of vessels and

means for thereafter continuing the feeding while periodically repeating the removing and replacing at least until all of the substantial plurality of vessels have been removed and replaced.