Relating to water treatment

Abstract

The present invention relates to water treatment. In one example, there is provided a method of treating an aqueous system to inhibit growth of one or more micro-organisms therein and/or to reduce the number of live micro-organisms therein. The method includes adding treatment agents to said aqueous system, wherein said treatment agents include: (a) a phosphonium compound; and (b) a stabilised halogen containing composition.

Claims

1. A method comprising: adding treatment agents to an aqueous system, the aqueous system comprising one or more salts, having a total dissolved solids (TDS) of 20,000 mg 1.sup.1 or greater, and containing Desulfovibrio vulgaris and Enterobacter aerogenes, the treatment agents comprising a combination of: (a) tri n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) a stabilised halogen containing composition which comprises bromosulfamate; wherein the combination of TTPC and stabilized halogen containing composition are added to the aqueous system in amounts configured to reduce the number of live Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous system; wherein said TTPC and said stabilized halogen containing composition are at a weight ratio of from 1.0:0.5 to 1.0:100.0; wherein said TTPC is added to said aqueous system in an amount of up to 70 parts by weight per one million parts by weight of said aqueous system (ppm); and wherein said TTPC and said bromosulfamate are added to the aqueous system in a total amount of from 0.1 to 1000 ppm.

2. A method according to claim 1, wherein the stabilised halogen containing composition (b) comprises a composition formed from an oxidizing bromine source or sodium bromide which has been oxidized by an oxidizing chlorine source, to give hypobromous acid with the hypobromous acid having been stabilised using sulfamic acid to provide bromosulfamate.

3. A method according to claim 1, wherein the stabilised halogen containing composition (b) comprises a stabiliser (c) and a halogen containing compound (d).

4. A method according to claim 3, wherein the halogen containing compound (d) comprises sodium bromide and wherein the stabiliser (c) comprises sulfamic acid.

5. A method according to claim 1, wherein the method comprises treating said aqueous system such that a Log 10 reduction of 7 or greater in a facultative anaerobe culture is obtained after a contact time of 24 hours.

6. A method according to claim 1, wherein the method comprises treating an aqueous system having a TDS of 30,000 mg 1.sup.1 or greater.

7. A method according to claim 1, wherein the method comprises adding said TTPC to said aqueous system in an amount of at least 0.1 ppm and not more than 25 ppm.

8. A method according to claim 3, wherein the method comprises adding the composition (b) to provide a treated aqueous system comprising hypobromous acid in an amount of at least 0.1 ppm.

9. A method according to claim 1, wherein the method comprises adding stabilised halogen containing composition (b) to said aqueous system in an amount of at least 10 ppm.

10. The method of claim 1, wherein: the aqueous system is an aqueous media, the aqueous media having a TDS of 30,000 mg 1.sup.1 or greater; the combination of TTPC and stabilised halogen containing composition are added to the aqueous media in amounts configured to inhibit the growth of Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous media; and said TTPC and said stabilized halogen containing composition are at a weight ratio of from 1.0:5.0 to 1.0:50.0.

11. A method according to claim 1, wherein the method comprises adding the composition (b) to provide a treated aqueous system comprising bromosulfamate in an amount of at least 0.1 ppm.

12. A method according to claim 1, wherein the aqueous system contains oil.

13. A method according to claim 1, wherein the method comprises treating said aqueous system such that a Log 10 reduction of 6 or greater in anaerobe culture is obtained after a contact time of 1 hour.

14. A method according to claim 2, wherein the stabilised halogen containing composition (b) comprises a bromine containing composition formed from sodium bromide which has been oxidized by solid trichloroisocyanuric acid to give hypobromous acid with the hypobromous acid having been stabilised using sulfamic acid to provide bromosulfamate.

15. A method according to claim 1, wherein said weight ratio is from 1.0:5.0 to 1.0:50.0.

16. A method comprising: adding treatment agents to an aqueous system, the aqueous system comprising one or more salts, having a total dissolved solids (TDS) of 30,000 mg 1.sup.1 or greater, and containing Desulfovibrio vulgaris and Enterobacter aerogenes, the treatment agents comprising a combination of: (i) tri n-butyl n-tetradecyl phosphonium chloride (TTPC); and (ii) bromosulfamate; wherein the combination of TTPC and bromosulfamate are added to the aqueous system in amounts configured to reduce the number of live Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous system; and wherein said TTPC and said bromosulfamate are at a weight ratio of from 1.0:5.0 to 1.0:50.0.

17. A method according to claim 16, wherein the method comprises adding TTPC to said aqueous system in an amount of at least 0.1 ppm and adding said bromosulfamate to said aqueous system in an amount of at least 0.1 ppm.

18. A method according to claim 16, wherein the method comprises treating an aqueous system such that a Log 10 reduction of 7 or greater in a facultative anaerobe culture is obtained after a contact time of 24 hours.

19. A method according to claim 16, wherein the amount of TTPC is from 1.0 to 20 parts by weight per one million parts by weight of said aqueous system (ppm) and the amount of bromosulfamate is from 10 ppm to 500 ppm.

20. A method according to claim 16, wherein the amount of TTPC is less than 12.5 parts by weight per one million parts by weight of said aqueous system (ppm) and the amount of bromosulfamate is less than 315 ppm.

21. A method according to claim 20, wherein the combination of TTPC and bromosulfamate are added to the aqueous system in amounts configured to reduce the number of live Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous system by a Log 10 reduction of 6 or greater within 24 hours of the adding.

22. A method according to claim 20, wherein the combination of TTPC and bromosulfamate are added to the aqueous system in amounts configured to provide a complete kill of Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous system within 24 hours of the adding.

23. A method comprising: adding treatment agents to an aqueous system, the aqueous system comprising one or more salts, having a total dissolved solids (TDS) of 30,000 mg 1.sup.1 or greater, and containing Desulfovibrio vulgaris and Enterobacter aerogenes, the treatment agents comprising a combination of: (i) tri n-butyl n-tetradecyl phosphonium chloride (TTPC); and (ii) stabilised halogen containing composition which comprises stabilised hypobromous acid; wherein the combination of TTPC and stabilised halogen containing composition are added to the aqueous system in amounts configured to reduce the number of live Desulfovibrio vulgaris and Enterobacter aerogenes in the aqueous system by a Log 10 reduction of 6 or greater within 24 hours of the adding; wherein said TTPC is added to said aqueous system in an amount of up to 70 parts by weight per one million parts by weight of said aqueous system (ppm); and wherein said TTPC and said stabilized hypobromous acid are added to said aqueous system in a total amount of from 0.1 ppm to 1000 ppm.

24. A method according to claim 23, wherein the method comprises adding said TTPC and said stabilised halogen containing composition to said aqueous system in a weight ratio of TTPC:stabilised halogen containing composition of from 1.0:5.0 to 1.0:50.0 and adding said TTPC in an amount of not more than 50 ppm.

25. A method according to claim 23, wherein the method further comprises inhibiting the growth of Desulfovibrio vulgaris and Enterobacter aerogenes.

26. A method according to claim 23, wherein the method further comprises inhibiting the growth of Desulfovibrio vulgaris and Enterobacter aerogenes and comprises adding said TTPC and said stabilised halogen containing composition to said aqueous system in a weight ratio respectively, of TTPC:stabilised halogen containing composition of from 1.0:5.0 to 1.0:50.0.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The present invention will now be illustrated by way of example with reference to the following preferred embodiments.

EXAMPLES

(2) Aqueous systems were treated by adding treatment agents comprising: (a) a phosphonium compound and (b) a stabilised halogen containing composition. The phosphonium compound (a) used was TTPC. The stabilised halogen containing composition (b) was a stabilised bromine composition which comprised sodium bromide stabilised to give bromosulfamate.

(3) A suspension of Desulfovibrio vulgaris plus Enterobacter aerogenes bacteria containing from 110.sup.6 to 110.sup.8 cells/mL was prepared in sterile pH 8 phosphate buffer containing varying levels of sodium chloride to give the desired total dissolved solids (TDS) concentration. Aliquots of this suspension were dosed with the indicated concentrations of the phosphonium compound (a) and stabilised halogen containing composition (b) with the concentrations being measured as ppm by weight of the stated composition in the dosed suspension. The mixtures were allowed to stand at room temperature. At the designated contact times, each mixture was sampled to determine the total number of viable cells of both Desulfovibrio vulgaris and Enterobacter aerogenes by serial 10-fold dilution into API RP 38 media vials and anaerobic acid producing media vials, respectively. The vials were incubated at 37 C. for 72 hours. Results were recorded as cells per millilitre.

(4) Aqueous media inoculated with anaerobe and aerobe culture and having a TDS of 30,000 mg l.sup.1 was treated with treatment agents comprising: (i) stabilised halogen containing composition; (ii) tri n-butyl n-tetradecyl phosphonium chloride (TTPC) or (iii) a combination of stabilised halogen containing composition and TTPC.

(5) TTPC was used in the form of Bellacide 350, an aqueous composition of TTPC and water consisting of water and 50% by weight of TTPC.

(6) The stabilised halogen containing composition comprised sodium bromide stabilised to give bromosulfamate and the composition used was Bromax 7.1 available from Enviro Tech Chemical Services, Inc. This composition comprises bromosulfamate produced by oxidising sodium bromide with trichloroisocyanuric acid to give hypobromous acid and stabilising the hypobromous acid using sulfamic acid to yield bromosulfamate. The activity of the composition is approximately 7.1% as chlorine.

(7) The efficacy of the treatment agents was evaluated by measuring the Log 10 Reduction of the anaerobic bacterium Desulfovibrio vulgaris and the facultative anaerobeic bacterium Enterobacter aerogenes after contact times of 1 hour, 4 hours and 24 hours as detailed in Table 1. For TTPC the stated ppm value relates to the amount of TTPC added (active). For the stabilised bromine composition the stated ppm relates to the amount of Bromax 7.1 added (product)

(8) TABLE-US-00001 TABLE 1 Treatment agent (ppm) Stabilized Log10 Contact TTPC bromine Log10 Reduction TDS time (as composition Reduction Facultative Example (mg l.sup.1) (hours) active) (as product) Anaerobes Anaerobes 1 (comparative) 30,000 1 6.25 3 1 2 (comparative) 30,000 1 12.5 6 4 3 (comparative) 30,000 1 105 4 1 4 (comparative) 30,000 1 210 5 5 5 (comparative) 30,000 1 315 6 8 6 30,000 1 3.125 105 6 1 7 30,000 1 6.25 105 6 1 8 30,000 1 12.5 105 6 5 9 (comparative) 30,000 4 6.25 6 5 10 (comparative) 30,000 4 12.5 6 5 11 (comparative) 30,000 4 105 5 1 12 (comparative) 30,000 4 210 6 5 13 (comparative) 30,000 4 315 6 8 14 30,000 4 3.125 105 6 5 15 30,000 4 6.25 105 6 7 16 30,000 4 12.5 105 6 8 17 (comparative) 30,000 24 6.25 6 5 18 (comparative) 30,000 24 12.5 6 8 19 (comparative) 30,000 24 105 6 2 20 (comparative) 30,000 24 210 6 5 21 (comparative) 30,000 24 315 6 8 22 30,000 24 3.125 105 6 8 23 30,000 24 6.25 105 6 8 24 30,000 24 12.5 105 6 8

(9) A Log 10 reduction of 6 represents a complete kill for anaerobes and a Log 10 reduction of 8 represents a complete kill for facultative anaerobes.

(10) It can be seen from the Examples that with a TDS of 30,000 mg l.sup.1 stabilised bromine shows some biocidal activity against anaerobes but the addition of TTPC surprisingly improved the performance with a 1 hour contact time. It can also be seen that although stabilised bromine has poor biocidal activity against facultative anaerobes the addition of TTPC greatly improves performance essentially providing complete kill at 24 hours.

(11) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(12) All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

(13) Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(14) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.