Water treatment

Abstract

A method treats 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 an aqueous system wherein said treatment agents include (a) a phosphonium compound; and (b) a compound having formula: M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2.

Claims

1. 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, wherein the method comprises adding treatment agents to an aqueous system having a total dissolved solids (TDS) of 10,000 mg l.sup.−1 or greater and wherein said treatment agents comprise: (a) tri-n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) a compound having formula:
M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2.

2. The method according to claim 1, wherein compound (b) is NaClO.sub.2.

3. The method according to claim 1, wherein compound (b) is NaClO.sub.2 and wherein the aqueous system comprises water in an amount of up to 99% by weight.

4. The method according to claim 1, wherein the method comprises adding compound (a) to the aqueous system in an amount of no more than 20 ppm and/or wherein the method comprises adding compound (b) to the aqueous system in an amount of no more than 300 ppm and/or wherein the method comprises adding compound (a) and compound (b) to the aqueous system in a combined amount of from 0.1 to 300 ppm.

5. The method according to claim 1, wherein the TDS is 30,000 mg l.sup.−1 or greater.

6. The method according to claim 1, wherein the method comprises adding compound (a) and compound (b) to the aqueous system in a weight ratio of from 10:1 to 1:60.

7. The method according to claim 1, wherein the method comprises treating the aqueous system to inhibit growth of anaerobic bacteria and to reduce the number of live anaerobic bacteria therein and/or wherein the method comprises treating the aqueous system to inhibit growth of aerobic bacteria and to reduce the number of live aerobic bacteria therein and/or wherein the method comprises treating the aqueous system to inhibit growth of facultative anaerobic bacteria and to reduce the number of live facultative anaerobic bacteria therein.

8. The method according to claim 1, wherein the method comprises adding TTPC and NaClO.sub.2 to the aqueous system, wherein the TTPC is added in an amount of 20 ppm or less and the TTPC and NaClO.sub.2 are added in a weight ratio of TTPC:NaClO.sub.2 of from 2:1 to 1:10.

9. The method according to claim 1, wherein the aqueous system is an oil and/or gas field water system and the TDS is 30,000 mg l.sup.−1 or greater and wherein the method comprises adding TTPC and NaClO.sub.2 to the aqueous system, wherein the TTPC is added in an amount of 20 ppm or less and the TTPC and NaClO.sub.2 are added in a weight ratio of TTPC:NaClO.sub.2 of from 2:1 to 1:10.

10. The method according to claim 1, wherein the aqueous system comprises oil in an amount of at least 1% by weight and/or wherein the method comprises treating industrial water.

11. The method according to claim 1, wherein the aqueous system is an oil and/or gas field water system and the TDS is 30,000 mg l.sup.−1 or greater, wherein the oil and gas field water system comprises oil in an amount of at least 1% by weight, wherein compound (b) is NaClO.sub.2, wherein the TTPC is added in an amount of 20 ppm or less and the TTPC and NaClO.sub.2 are added in a weight ratio of TTPC:NaClO.sub.2 of from 2:1 to 1:10, and wherein the method comprises treating the aqueous system to inhibit growth of Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria therein and/or to reduce the number of live Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria therein.

12. The method according to claim 1, wherein the aqueous system is an oil and/or gas field water system and the TDS is 30,000 mg l.sup.−1 or greater, wherein the oil and gas field water system comprises oil in an amount of at least 1% by weight, wherein compound (b) is NaClO.sub.2, and wherein the TTPC is added in an amount of 20 ppm or less and the TTPC and NaClO.sub.2 are added in a weight ratio of TTPC:NaClO.sub.2 of from 2:1 to 1:10.

13. The method according to claim 1, wherein the method comprises treating the aqueous system to inhibit growth of Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria therein and/or to reduce the number of live Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria therein.

14. The method according to claim 1, wherein the TDS is greater than 20,000 mg l.sup.−1 and the method inhibits growth of one or more micro-organisms therein and/or reduces the number of live micro-organisms therein, wherein the method comprises adding treatment agents to said aqueous system and wherein said treatment agents comprise a combination of: (a) tri-n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) NaClO.sub.2; wherein the combination of TTPC and NaClO.sub.2 are added to the aqueous system in amounts configured to inhibit growth of the one or more micro-organisms therein and/or to reduce the number of live micro-organisms therein.

15. An aqueous system comprising a combination of: (a) tri-n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) a compound having formula:
M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2; wherein the aqueous system has a total dissolved solids (TDS) of 10,000 mg l.sup.−1 or greater.

16. A biocidal composition comprising a combination of: (a) tri-n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) a compound having formula:
M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2; wherein the biocidal composition treats an aqueous system having a total dissolved solids (TDS) of 10,000 mg l.sup.−1 or greater.

17. A method of inhibiting or preventing the growth of one or more micro-organisms in a water-based liquid having a total dissolved solids (TDS) of 10,000 mg l.sup.−1 or greater, wherein the method comprises adding treatment agents to said water-based liquid and wherein said treatment agents comprise: (a) a phosphonium compound; and (b) a compound having formula:
M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2.

18. The method according to claim 17, wherein the method comprises inhibiting or preventing the growth of Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria in the water-based liquid.

19. A method according to claim 17, wherein the water-based liquid comprises Desulfovibrio vulgaris bacteria and Enterobacter aerogenes bacteria, the TDS being 30,000 mg l.sup.−1 or greater, and the treatment agents comprising: (a) tri-n-butyl n-tetradecyl phosphonium chloride (TTPC); and (b) NaClO.sub.2; wherein the amounts of TTPC and NaClO.sub.2 are selected such that the treatment agents provide a complete kill of the Desulfovibrio vulgaris bacteria and the Enterobacter aerogenes bacteria within a contact time of four hours.

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 inoculated with anaerobe and facultative anaerobe culture and having a total dissolved solids (TDS) concentration of 30,000 mg l.sup.−1 were prepared and treated with treatment agents comprising: (a) tri n-butyl n-tetradecyl phosphonium chloride (TTPC) and (b) NaClO.sub.2.

(3) 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 available from BWA Water Additives.

(4) NaClO.sub.2 was used in the form of Reagan Grade Sodium Chlorite, an 80% aqueous solution of NaClO.sub.2 available from Amresco.

(5) A suspension of Desulfovibrio vulgaris plus Enterobacter aerogenes bacteria containing from 1×10.sup.5 to 1×10.sup.6 cells/mL was prepared in sterile pH 8 phosphate buffer containing sodium chloride to give the desired total dissolved solids (TDS) concentration. Aliquots of this suspension were dosed with the indicated concentrations of the compounds (a) and (b) with the concentrations being measured as ppm active. 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 log.sub.10 reduction in the viable count versus the control.

(6) The efficacy of the treatment agents was evaluated by measuring the Log.sub.10 Reduction of the anaerobic bacterium Desulfovibrio vulgaris and the facultative anaerobic 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 NaClO.sub.2 the stated ppm relates to the amount of NaClO.sub.2 added (active).

(7) TABLE-US-00001 TABLE 1 Log.sub.10 Contact Treatment agent Log.sub.10 Reduction TDS time (ppm active) Reduction Facultative Example pH (mg l.sup.−1) (hours) TTPC NaClO.sub.2 Anaerobes* Anaerobes**  1(comparative) 8.0 30,000 1 6.25 — 2 0  2(comparative) 8.0 30,000 1 12.5 — 5 3  3(comparative) 8.0 30,000 1 — 10 0 0  4(comparative) 8.0 30,000 1 — 20 0 0  5 8.0 30,000 1 6.25 10 5 1  6 8.0 30,000 1 6.25 20 5 1  7 8.0 30,000 1 12.5 10 5 4  8 8.0 30,000 1 12.5 20 5 6  9(comparative) 8.0 30,000 4 6.25 — 5 3 10(comparative) 8.0 30,000 4 12.5 — 5 4 11(comparative) 8.0 30,000 4 — 10 0 0 12(comparative) 8.0 30,000 4 — 20 1 0 13 8.0 30,000 4 6.25 10 5 6 14 8.0 30,000 4 6.25 20 5 6 15 8.0 30,000 4 12.5 10 5 6 16 8.0 30,000 4 12.5 20 5 6 17(comparative) 8.0 30,000 24 6.25 — 5 5 18(comparative) 8.0 30,000 24 12.5 — 5 6 19(comparative) 8.0 30,000 24 — 10 4 0 20(comparative) 8.0 30,000 24 — 20 4 0 21 8.0 30,000 24 6.25 10 5 6 22 8.0 30,000 24 6.25 20 5 6 23 8.0 30,000 24 12.5 10 5 6 24 8.0 30,000 24 12.5 20 5 6 *5 = complete kill for anaerobes **6 = complete kill for facultative anaerobes

(8) The results show that surprisingly, despite NaClO.sub.2 being ineffective alone against anaerobes at short contact times and of limited effectiveness at longer contact times the combination of TTPC and NaClO.sub.2 was very effective against anaerobes, achieving complete kill (5 log reduction) at one-hour contact times.

(9) The results with facultative anaerobes also show unexpected efficacy of the combination of TTPC and NaClO.sub.2 with the combination achieving complete kill (6 log reduction) at 4 hours contact time.

(10) It is particularly surprising that low levels of TTPC are effective with low levels of NaClO.sub.2. Accordingly, it will be appreciated that combining TTPC and NaClO.sub.2 may allow for less TTPC to be used to achieve kill of facultative anaerobes and anaerobes compared to TTPC alone. It will also be appreciated that combining TTPC and NaClO.sub.2 may allow for complete kill of facultative anaerobes and anaerobes using TTPC and NaClO.sub.2 at certain contact times which may not be achievable if using TTPC only.

(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.