Process and apparatus for treating drinking water

• US 4,198,296 A
• Filed: 07/10/1978
• Issued: 04/15/1980
• Est. Priority Date: 04/29/1975
• Status: Expired due to Term

• Current Assignee: ELX Holdings LLC
• Original Assignee: Consolidated Foods Limited (Gablewoods Supermart Limited)
• Inventors: Molof, Alan H., Raymond, Gordon H., Doumas, John J., Wikstrom, Lee
• Primary Examiner(s): Hart, Charles N.
• Assistant Examiner(s): Cross, E. Rollins
• Application Number:
  US05/922,935
• Time in Patent Office: 645 Days
• Field of Search: 210/501, 210/29, 210/32, 210/37 R, 210/63 R, 210/63 Z, 210/64, 210/198 R, 210/209, 210/259
• US Class Current: 210/668
• CPC Class Codes: B01J 41/04 Processes using organic exchangers
• CPC Class Codes: C02F 1/281 using inorganic sorbents
• CPC Class Codes: C02F 1/283 using coal, charred products, or inorganic mixtures containing them
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 1/505 by oligodynamic treatment
• CPC Class Codes: C02F 1/722 Oxidation by peroxides
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 2001/422 using anionic exchangers
• CPC Class Codes: C02F 2001/425 using cation exchangers
• CPC Class Codes: C02F 2301/043 Treatment of partial or bypass streams
• CPC Class Codes: C02F 2303/04 Disinfection
• CPC Class Codes: C02F 2303/18 Removal of treatment agents after treatment
• CPC Class Codes: C02F 2303/185 The treatment agent being halogen or a halogenated compound

Abstract

This invention relates to the discovery that chemicals existing in natural waters, which have been pretreated in municipal water treatment facilities, as well as natural surface and underground waters which have not been so pretreated, do inhibit the biocidal effect of known water disinfectants of the metallic ion type. This may be overcome by exchanging for the halide ions in such water an anion, such as bicarbonates, which does not inhibit the biocidal effect of metallic ions, nor does it react chemically with known oxidizing biocides to form halogenated organics which are suspected of causing cancer. Further, water treated in accordance with this invention substantially maintains its original ionic character to maintain the water in a natural state, for example, not deionized.

In accordance with another aspect of the invention, water which has been municipally treated with oxidizing biocides and may contain halogenated organics is pretreated to remove the halogenated organics prior to the removal of halides referred to above.

Claims

1. A method of producing biologically safe drinking water from natural water comprising the steps of removing halide ions from said natural water and exchanging for said halide ions an anion which will substantially maintain the original ionic character of said natural water and not inhibit the biocidal effects of bactericides, and introducing a bactericide to said water in a biologically acceptable amount to kill bacteria in said water.

2. The method according to claim 1, in which the step of introducing the bacteria includes the use of an amount to rapidly kill the bacteria, followed by reducing said bactericide to a biologically acceptable amount after it has acted as a bactericide.

3. The method according to claim 1 wherein said bactericide is a metallic ion.

4. The method according to claim 1 wherein said bactericide is an oxidizing agent.

5. A method according to claim 1 wherein one portion of said natural water is deionized while the other portion thereof is not so treated and both the deionized and untreated portions are combined before halide ion removal.

6. The method according to claim 1 wherein one portion of said natural water is deionized while the other portion of said water has the halide ions removed therefrom and both said portions are brought together prior to introducing the disinfectant thereto.

7. The method according to claim 1 wherein said bactericide is selected from the group consisting of silver ions, ozone, permanganate, peroxide, mercury, ferrate, persulfate and argentic.

8. A method according to claim 7 comprising the steps of introducing as a bactericide mercury ions substantially in excess of 2 micrograms per liter, holding the treated water containing said mercury ions for a period of time sufficient for said mercury ions to act as a bactericide, and thereafter reducing the mercury ions in said water to not more than 2 micrograms per liter.

9. A method for producing biologically safe drinking water from natural water comprising the steps of removing the halide ions from said natural water and exchanging for said halide ions an anion which substantially maintains the ionic character of said water, introducing silver ions substantially in excess of 50 micrograms per liter to the resulting water, holding the water containing said silver ions for a period of time sufficient for said silver ions to act as a bactericide, and thereafter reducing the silver ions in said water to not more than 50 micrograms per liter.

10. The method according to claim 9 wherein the step of reducing the silver ions is accomplished by contacting the water with an anion exchange resin regenerated with an anion that forms a silver salt of low solubility and which is associated with the anion exchange resin.

11. The method according to claim 10 wherein the anion resin is in the chloride form.

12. The method according to claim 11 wherein said resin for removing halide ions and said resin for removing silver ions are sanitized by a silver wash while being regenerated in the bicarbonate and chloride form respectively.

13. A method according to claim 9 wherein said silver ions are introduced into said resulting water by passing the water through a medium containing a silver salt whose solubility product provides a silver ion concentration in excess of 50 micrograms per liter.

14. A method according to claim 13 wherein said medium is selected from the group consisting of activated charcoal, alumina, silica gel and diatomaceous earth.

15. The method according to claim 9 wherein said halide ions are removed by passing said water through a bed of halide ion removing anionic resin.

16. The method according to claim 15 wherein said anionic resin is regenerated in the bicarbonate form and imparts bicarbonate ion to said treated water to retain the natural character of the treated water.

17. A method for producing biologically safe drinking water from natural water comprising the steps of removing the halide ions from said natural water and exchanging for said halide ions an anion which substantially maintains the ionic character of said water, introducing silver ions substantially in excess of 50 micrograms per liter, introducing an oxidizing disinfectant or combination of such disinfectants, holding the treated water for a period of time sufficient for bactericidal effect, and thereafter reducing the silver ions in said water to not more than 50 micrograms per liter and removing said oxidizing disinfectants.

18. A method of producing biologically safe drinking water from natural water comprising the steps of removing halide ions from said natural water and exchanging for said halide ions an ion which will substantially maintain the original ionic character of said natural water and not form halogenated organics with oxidizing bactericides nor inhibit the biocidal effects of said oxidizing bactericides and introducing an oxidizing bactericide to said water in a biologically acceptable amount to kill bacteria in said water.

19. The method according to claim 18, in which the step of introducing said bactericide includes the use of an amount to rapidly kill the bacteria, followed by reducing said bactericide to a biologically acceptable level after it has acted as a bactericide.

20. The method according to claim 18 wherein said ion exchanged for said halide ions is an anionic bicarbonate ion.