WO2022118313A1

WO2022118313A1 - Method and composition for water treatment

Info

Publication number: WO2022118313A1
Application number: PCT/IL2021/051430
Authority: WO
Inventors: Michal RODENSKY; Chen Zolkov; Jakob Oren; Nir GOLDSTEIN; Ari Ayalon
Original assignee: Bromine Compounds Ltd.
Priority date: 2020-12-02
Filing date: 2021-12-01
Publication date: 2022-06-09

Abstract

A method of microbial control in water comprising adding to the water one or more bromine-based biocide(s) and at least one fatty acid additive or a salt thereof (other than monounsaturated fatty acids in which the carbon-carbon double bond is at position 2).

Description

Method and composition for water treatment

The invention relates to microbial control of water, e.g., eliminating planktonic and biofilm bacteria using a brominebased biocide in combination with an auxiliary agent which has been found to enhance the action of the biocide.

The use of bromine in industrial water treatment is well established and a variety of bromine-based biocides are currently available in the market. The working concentrations and frequency of supply of the biocide depend on the type of water, microbial load, organic load, the specific biocide under consideration, the dosing method, etc.

Control of biofilm constitutes an important aspect of water treatment programs. In US 2009/0178587, the performance of bromine-based biocides in controlling biofilms of P. aeruginosa was investigated. It has been also proposed in US 2009/0178587 to increase the efficiency of the treatment with the aid of surfactants that act as bio-dispersants, but no experimental data was given to illustrate this approach. Furthermore, the publication WO 2019/079107 relates to methods of controlling biofilm by using, among others, bromine-based biocides and a biofilm-disrupting agent or a bio-dispersant.

It was previously reported that unsaturated fatty acids affect quorum sensing communication system and inhibit motility and biofilm formation of Aci netobacter baumannii (International Journal of Molecular Sciences (2018) , 19(1) , 214/1-214/10) . The combined effect of linolenic acid and tobramycin on Pseudomonas aeruginosa biofilm formation and quorum sensing was also reported (Experimental and Therapeutic Medicine (2017) , 14 (5) , 4328-4338) . Furthermore, the publication WO 2015/076830 relates to methods and compositions for dispersing a biofilm in an aqueous stream using fatty acids and additional agents , inter alia a bromine-based antimicrobial agent .

In co-assigned PCT/ IL2020/ 050591 (=WO 2020/240559 ) it was demonstrated that cis-2-decenoic acid ( CDA) can act as an ef fective adj unctive to bromine-containing biocides in the treatment of biofilm and planktonic bacteria in water systems and on surfaces in contact with the water, to achieve signi ficant enhancement in the killing of bacteria in both pure and mixed cultures typically found in industrial and natural waters , relative to treatment with the brominated biocides alone .

The present invention describes a method for enhancing the ef ficacy of biocides & disinfectants , speci fically of brominebased biocides , which are used for the treatment of biofilm and planktonic bacteria in water systems and on surfaces in contact with the water .

Experimental work conducted in support of this invention in laboratory models indicates that the use of unsaturated fatty acids ( speci fical ly, Omega 3 fatty acids and fatty acids derived from Joj oba oil ) acting as biofilm dispersion agents in conj ugation with bromine-based biocides showed a synergistic ef fect for biofilm control . Based on the synergistic ef fect observed, the combination of very low concentrations of unsaturated fatty acids with brominated biocides allows for a reduction in the ef fective quantities of the biocides used .

The invention is therefore primarily directed to a method of microbial control in water, comprising adding to the water one or more bromine-based biocide ( s ) and at least one fatty acid additive or a salt thereof ( other than monounsaturated fatty acids in which the carbon-carbon double bond is at position 2 ) , to achieve , for example , reduction of planktonic and/or biofilm bacteria, protist (e.g. algae) and fungi on a surface in contact with the water. Hereinafter we use the term "additive" to indicate the fatty acid acting as adjunctive to brominecontaining biocides.

It should be appreciated that by the term "microbial control" as used herein it is referred to reducing, eliminating or inhibiting microbial growth and/or biofilm formation and to the disruption of established biofilm.

As known in the art, a biofilm is a complex aggregation of microorganisms known by its excretion of a protective and adhesive matrix. Biofilms are characterized by surface attachment, structural heterogeneity, genetic diversity, complex community interactions and an extracellular matrix of polymeric substances .

Microbial biofilms formed on surfaces are costly due to industrial equipment damage, product contamination, energy loss and medical infections they may cause. Conventional methods of killing bacteria (such as antibiotics and disinfection agents) are often ineffective on biofilm bacteria.

Due to the extracellular matrix and general structure of the biofilm, biofilms are more resistant to biocidal attack. As a consequence, biocides used to inhibit growth of conventional cultures growing in suspension are less effective, if at all, in combating the formation of biofilm structures or in the disruption of established biofilms.

However, as pointed out above, additives according to the invention have been found by the inventors to act efficiently as adjunctive to bromine-containing biocides. The fatty acid of the invention may be artificially (i.e. synthetically prepared) or naturally sourced and can be a cis or trans fatty acid, or a combination of both. The fatty acid may be linear or branched, preferably linear. Naturally sourced fatty acids may come from animal or plant sources, including, but not limited to, fish oil, beef fat, krill oil, fowl fat, Jojoba oil, olive oil, palm oil, canola oil, soya oil, corn oil and seaweed.

Suitable fatty acids may be saturated or unsaturated (such as polyunsaturated) fatty acids, or a combination of both. Unsaturated fatty acids include, but are not limited to, (Z)- tetradec- 9-enoic acid, hexadec-9-enoic acid, ( Z ) - 6-hexadecenoic acid, ( 9Z , HE, 13E ) -octadeca-9, 11 , 13-trienoic acid, (9Z) — octadec-9-enoic acid, (E) -octadec-9-enoic acid, (E ) -octadec-H- enoic acid, ( 9Z, 12Z ) -9, 12-octadecadienoic acid, (9E,12E)- octadeca-9, 12-dienoic acid, ( 9Z , 12Z , 15Z ) -9, 12 , 15- octadecatrienoic acid, (5Z, 8Z, HZ, 14Z) -5, 8, 11, 14- eicosatetraenoic acid, (5Z, 8Z, 11Z, 14Z, 17Z) -5, 8, 11, 14, 17- icosapentaenoic acid (also termed Eicosapentaenoic acid, EPA) , ( Z ) -docos-13-enoic acid, (4Z,7Z,10Z,13Z,16Z,19Z)-docosa- 4, 7, 10, 13, 16, 19-hexaenoic acid (also termed Docosahexaenoic acid DHA) , 11-eicosenoic acid (Gondoic acid) , ci s-13-docosenoic acid (Erucic acid) , ci s-9 oleic acid (Oleic acid) , Myristoleic acid ( 9-tetradecenoic acid) , Alpha-Linolenic acid (ALA) and combinations thereof.

One preferred additive comprises at least one of: monounsaturated fatty acid bearing not less than 20 carbons or alkali salts thereof, e.g., one or more of:

11-eicosenoic acid (Gondoic acid; 20:1 All) and cis-13- docosenoic acid (Erucic acid; 22:1 A13) ; polyunsaturated fatty acid bearing not less than 20 carbons or alkali salts thereof, e.g., one or more of Eicosapentaenoic acid ( (5Z, 8Z, 11Z, 14Z, 17Z) -5, 8, 11, 14, 17- icosapentaenoic acid) , Docosahexaenoic acid ( (4Z, 7Z, 10Z, 13Z, 16Z, 19Z) -docosa-4, 7, 10, 13, 16, 19 -hexaenoic acid)

Arachidonic acid (20:4 A5, 8, 11, 14) and Docotetrasenoic acid (22 : 4 A7, 10, 13, 16) .

One additional additive is cis-9 oleic acid (Oleic acid) .

As detailed below, effective removal of biofilm was shown for combinations containing additives which are fatty acids obtainable by hydrolysis of Jojoba oil (namely for Jojoba oil- derived fatty acids) , specifically for hydrolysis of Jojoba oil in which the hydrolysate composition comprises jojoba fatty acid (FA) having the structure CH3- (CH2) 7-CH=CH- (CH2) _m-COOH, where m= 7, 9, 11 or 13.

The present invention therefore encompasses the use of additives which are fatty acid derivatives of jojoba oil. Jojoba oil-wax (JO) is extracted from the seeds of the Jojoba, a perennial shrub that grows in semi-arid areas in some parts of the world. The main uses of JO are in the cosmetics and pharmaceutical industries. The fatty acid components of Jojoba wax esters primarily consist of oleic, gondoic, erucic, arachidonic and docotetrasenoic acids, with additional acids as detailed in Table 1 below.

Fatty acids derived from jojoba may be obtained by any method known to one of skill in the art (e.g. as described in IN178981) . By a further example, Jojoba Fatty Acids (FA) may be prepared by the hydrolysis of JO with an alcoholic (methanol, ethanol and 2- propanol) solution of KOH followed by acidification.

An exemplary fatty acid (FA) profile of Jojoba oil methyl esters (JME) is shown in Table 1 below. The average molecular weight of JME is 326 g/mol, which was calculated from the FA profile. Table 1 Fatty acid composition (in weight percent) of JME

³ The first number indicates the length of the fatty acid chain and the second, the number of double bonds (all cis) with A signifying the location of the double bond(s) . b 2 sat=16: 0+22 : 0 c 2 monounsat=18 : 1+20 : 1+22 : 1+24 : 1 d 2 polyunsat=18 : 2+18 : 3+20 : 4+22 : 4

Therefore the methods of the invention are applicable wherein the fatty acid additive is Gondoic, Erucic or Oleic acid or any combination thereof.

In particular the use of an additive composition comprising Gondoic acid at a range of from 10 to 70% (e.g. from 10 to 60% or from 40 to 60%) , Erucic at a range of from 10 to 70% (e.g. from 10 to 40% or from 10 to 30%) and Oleic acid at a range of from 10 to 70% (e.g. from 10 to 40% or from 10 to 30%) by weight is encompassed by the present invention, as well as an additive composition comprising the corresponding salts of the mentioned fatty acids (e.g. potassium salts) . The present invention further exemplifies the efficacy of additives such as Omega 3 fatty acids on biofilm removal and prevention by various biocides . The additive may be a mixture comprising EDA (Eicosapentaenoic acid - 20:5) and DHA (Docosahexaenoic acid - 22:6) at weight ratio of 1:2 to 2:1, for example, equally proportioned mixture around 1:1, optionally alongside other fatty acids as minor components. A commercial source is, for example, Omega-3 600 mg fish oil capsules, the fatty acid composition of which being 30% EDA (Eicosapentaenoic acid - 20:5) , 30% DHA (Docosahexaenoic acid - 22:6) and 10% other Omega-3 fatty acids (Supherb, Noff Hagalil, Israel, for Vitamed Pharm. Ind. ) .

In particular the use of an additive composition comprising Eicosapentaenoic acid at a range of from 10 to 50% (e.g. from 20 to 40%) and Docosahexaenoic acid at a range of 10-50% (e.g. from 20 to 40%) by weight is encompassed by the present invention.

Other fatty acids that were considered within the framework of this invention were Myristoleic acid (14:1) , Palmitoleic acid (16:1) and Alpha-Linolenic acid (18:3) . As indicated above, the first number indicates the length of the fatty acid chain and the second number indicates the number of double bonds.

The additive as herein defined can be easily incorporated into bromine delivery systems that are currently employed in the treatment of industrial water. For example, the bromine-based biocide (s) and the additive as herein defined can be delivered to an industrial water stream in contact with an infested surface using multiple feed solutions injected sequentially or simultaneously, either continuously or in batch mode to the water stream; the simultaneous injection may include the pre-mixing of the individual solutions to produce a single additive solution

(i.e., the additive and biocide solutions can be mixed before or just prior to addition to the water stream) . The selected feeding method also depends on whether the biocide is supplied as a single component or not, as described below.

To enable water treatment using a single additive feed instead of multiple additives feeds, liquid concentrates comprising suitably proportioned combinations of bromine-based biocide and additive as herein defined may be prepared.

Another aspect of the invention is a composition (e.g., a liquid concentrate) comprising one or more bromine-based biocides and one or more additive (s) in a liquid carrier comprising water, water miscible solvent or mixture thereof, and optionally one or more additive (s) such as cosolvent ( s ) , antifreeze ( s ) and stabilizer ( s ) , e.g., antioxidants. Solid compositions comprising the biocide and additive, e.g., granules, flakes & tablets, are also contemplated by the present invention.

Bromine-based biocides suitable for use in the present invention are available in the marketplace in different forms, i.e., solids such as powders and compacted forms (e.g., granules and tablets) and liquids (e.g., aqueous concentrates or other flowable formulations that can be easily supplied to the aqueous system to be treated) . The bromine-based biocidal agents are commonly divided into two classes:

A) non-oxidizing biocides; and

B) oxidizing biocides.

Non-oxidizing biocides may be selected from the group of:

Al: 2-bromo-2-nitro-l , 3-propanediol (bronopol) ; the synthesis of bronopol is described, for example, in WO 2009/107133. The product is available (e.g., from ICL-IP) in a powder form or an aqueous solution and its normal dose level as active ingredient lies in the range from 1 to 1000 ppm (when used alone, e.g., from 1 to 300 ppm) .

A2 : 2 , 2-dibromo-3-nitrilopropionamide ; the synthesis of DBNPA is described, for example, in US 4,328,171. Aqueous concentrates and compacted forms of DBNPA are described in US 5, 627,135 and US 7,524,884, respectively. DBNPA is commercially available (e.g., from ICL-IP) . When used alone, dose rates as active ingredient are in the range from 1 to 1000 ppm (e.g., 1-200 ppm) .

A3: other examples of non-oxidizing bromine-based biocides that can be mentioned include 2-Bromo-4-hydroxyacetophenone (BHAP) , bis-bromo acetyl butene (BBAB) , p-bromo-p-nitro-styrene (BNS) , bromine based biocide based on Malonamide and 1 , 2-Dibromo-2 , 4- dicyanobutane (DBDCB) .

Oxidizing bromine-based biocides are compounds which release active bromine species in water (e.g., hypobromous acid/hypobromite) , either by dissolution/ dissociation or through bromide oxidation that converts the Bn to elemental bromine/Br⁺ (the oxidation is usually achieved with the aid of a chemical oxidant; however, supply of electrolytically-generated bromine to the water system to be treated is also included herein in conjunction with the additive as herein defined) . The dosage of the oxidative biocides described herein is usually expressed as total CI2 that can be determined by iodometric titration using a titroprocessor : Titrino 848 plus or by DPD (Diethyl-p- PhenyleneDiamine ) reagent method using a SQ-300 spectrophotometer: Merck SQ-300. Oxidizing bromine-based biocides may be selected from the group of:

Bl : N-brominated amides and imides, such as 1 , 3-dihalo-5, 5- dialkylhydantoins, wherein at least one of the halogen atoms is bromine (the alkyl groups may be the same or different) ; commercially important biocides that belong to this class are 1- bromo-3-chloro-5, 5-dimethylhydantoin (abbreviated BCDMH) , 1- chloro-3-bromo-5, 5-dimethylhydantoin, 1, 3-dibromo-5, 5- dimethylhydantoin (DBDMH) and also "mixed" alkyl compounds containing two different alkyl groups at position 5 of the ring, such as l-bromo-3-chloro-methylethylhydantoin (BCMEH) , 1- chloro-3-bromo-methylethylhydantoin or mixtures thereof. Methods of synthesizing 1 , 3-dihalo-5, 5-dimethylhydantoins can be found, for example, in US 4,745,189. The acceptable dose rate of 1 , 3-dihalo-5, 5-dialkylhydantoins is 1 to 50 ppm as total CI2.

B2 : inorganic bromide sources, namely bromide salts (e.g., alkali metal salts, ammonium bromide) and hydrobromic acid, which release bromine species in water upon oxidation (e.g., by chemical oxidation using, for example, hypochlorite, chlorine gas, hydrogen peroxide or ozone; and by electrochemical oxidation, namely, anodically-generated bromine) . Commercially important products include activated sodium bromide (consisting of an aqueous solution of sodium bromide and sodium hypochlorite prepared on-site and delivered immediately to the water system to be treated) ; activated ammonium bromide (the biocide is prepared on-site by reacting ammonium bromide with an oxidizer) ; solution of HBr and urea which reacts with e.g., sodium hypochlorite on-site (e.g., Bactebrom® solution, composed of HBr and urea, from ICL-IP; the resulting active form is sometimes named herein bromourea) ; and dry mixtures of bromide/chlorine compound that are fed, for example, in a tablet form directly into the water system to be treated to react in-situ and produce the active bromine species . The abovementioned bromide sources such as sodium bromide, hydrobromic acid, ammonium bromide and the solution of HBr (or NaBr) and urea may be oxidized on-site chemically (e.g., with hypochlorite, chlorine gas, hydrogen peroxide or ozone) or electrochemically. B3 : Other examples of oxidizing bromine-based biocides include sulfamate-stabilized bromine-based biocides for example as described in WO 99/06320 (stabilized aqueous alkali/alkaline earth metal hypobromite solution (e.g., NaBr as bromide source) ) , or WO 03/093171, available from ICL-IP as Bromosol®, and bromine chloride and stabilized forms thereof (see US 6,068,861) available in the market as aqueous concentrates. For example, first, the alkali hypobromite is prepared, either by the reaction of a water soluble bromide source, such as NaBr, with alkali hypochlorite, such as NaOCl; or by addition of elemental bromine to aqueous alkali hydroxide solution (~30 wt . % NaOH solution) . Next, sulfamic acid, usually in the form of the in-situ prepared sodium sulfamate salt, is added to the hypobromite solution.

Turning now to the additive of the invention, it can be used as pure oil dissolved in a suitable solvent, such as ethanol, glycols, polyethylene glycol, DMSO, DMF, water miscible solvent or a mixture thereof (i.e., water alone, organic solvent alone or aqueous/organic solvent system) .

The combinations bromine/Omega 3 fatty acid(s) and bromine/ Jo oba-derived fatty acid(s) have proved surprisingly effective against biofilm in laboratory models, as shown below. Biofilm-associated bacterial counts measured for the combined treatment are at least about 1.5 log units lower than for comparative values measured for the biocide acting alone.

The term "enhancement" is used herein to indicate the difference in bacterial counts between treatments in which the biocide acts alone and treatments in which the biocide acts in combination with the additive as herein defined (the additive on its own does not reduce bacterial counts, as shown by the assays reported below for Omega 3 or Jojoba-derived fatty acids) . The performance of some selected bromine biocides, alone and in conjunction with Omega 3 fatty acid(s) is tabulated in Table 2. The results show the effect of bromine/Omega 3 fatty acid(s) on 3-day-old P. aeruginosa biofilm after one hour contact time with Omega 3 fatty acid(s) , followed by one hour contact time with the bromine-based biocide, at dosage levels of 310 nM and 2.5 - 10 ppm, respectively.

Table 2: effect of sequential application of Omega 3 fatty acid(s) and bromine biocide on 3-day-old Pseudomonas aeruginosa biofilm

Concentration as CI2

The performance of BCDMH, alone and in conjunction with Jojoba- derived fatty acid(s) is tabulated in Table 3. The results show the effect of bromine/ Jo j oba-derived fatty acid(s) on 3-day-old P. aeruginosa biofilm after one hour contact time with Jojoba- derived fatty acid(s) , followed by one hour contact time with the bromine-based biocide, at dosage levels of 310 nM, 3100 nM and 31000 nm and 5 - 10 ppm, respectively.

Table 3: effect of sequential application of Jojoba-derived fatty acid(s) and bromine biocide on 3-day-old Pseudomonas aeruginosa biofilm

Thus, l-bromo-3-chloro-5, 5-dimethylhydantoin (BCDMH) and 2,2- dibromo-3-nitrilopropionamide (DBNPA) are the preferred bromine- based biocides for use with Omega 3 or Jojoba-derived fatty acid(s) , i.e., with the mixtures of fatty acids described above.

In view of the above, bromine-based water treatments could benefit from the addition of an additive as herein defined, e.g. Omega 3 or Jo oba-derived fatty acid(s) in a number of ways:

1) Because the fatty acid(s) exemplified herein below have been shown to be bioactive in the presence of bromine-containing biocides within the range of concentrations typically used to treat biofouling in water systems, the additive as herein defined may be straightforwardly incorporated into bromine-based water treatment programs under the regular dosage levels and frequency of biocide dosing according to the program, i.e., without altering the rate of application of the biocide, to achieve improved biofilm control by periodically or continuously injecting the additive as herein defined into the water stream that comes in contact with the biofilm (prior to, simultaneously with, or subsequent to biocide delivery to the water) , or on occasion, especially in response to an indication of formation of highly severe biofilm, to achieve rapid control.

Accordingly, another aspect of the invention is a method of microbial control in water, which comprises combatting biofilm bacteria on a surface in contact with the water and/or inhibiting biofilm formation on a surface prone to such formation, by adding to the water an effective microbiocidal amount of the brominebased biocide (s) and an enhancement-inducing amount of the additive as herein defined to achieve biofilm reduction which is at least 1.5 log units (e.g., at least 2 or 3 log units) higher than the log reduction achieved with the same dosage of the biocide acting alone, for example, down to <10⁵ CFU/cm², e.g., <10³ CFU/cm² and preferably <10² CFU/cm² or even substantial biofilm eradication, i.e. <10² CFU/cm². By the term "inhibiting biofilm formation" as used herein it is meant to also include inducing dispersion of established biofilm.

The effective microbiocidal amount of the bromine-based biocide(s) is from 0.1 to 1000, e.g., 0.1 to 300 ppm as active biocide, for example, 0.1 to 100 ppm; 0.2 to 100 ppm; 0.5 to 100 ppm; 1.0 to 100 ppm, and the enhancement-inducing amount of the additive as herein defined is from 1 nM to 30 mM. It should be borne in mind that dosage levels may vary broadly depending on factors such as the identity of biocide and intended use. But in general, effective dosing ratios biocide : additive as w/w in the water stream may vary in the range from 20:1 to 5000:1 preferably from 100:1 to 3000:1. The enhancement-inducing amount of the additive can be determined by trial and error in the site of use to achieve targeted biofilm reduction.

For example, an enhancement-inducing amount of the additive could be from 0.001 to 15 ppm, e.g., from 0.005 to 10 ppm, for example, from 0.01 to 10 ppm or from 0.005 to 0.5 ppm. As shown below, good results were observed across 0.01 to 10 ppm (e.g., from 50 nM to 1000 nM, e.g. from 100 nM to 500 nM) .

2) As detailed above, based on the synergistic effect shown by the inventors, the combination of very low concentrations of the additive as herein defined with brominated biocides allows for a reduction in the effective quantities of the biocides used.

For example, the water system may be tracked for residual bromine and once the residual bromine values decay below a predetermined threshold, the additive as herein defined can be injected to support the maintenance of the system with the low residual bromine to inhibit biofilm formation. That is, to enhance the activity of residual biocide in a water sample any time over the period of time that an active biocide is present in a system .

Accordingly, another aspect of the invention is a method of industrial water treatment comprising supplying bromine-based biocide ( s ) to the water for combatting biofilm bacteria on a surface in contact with the water and/or inhibiting biofilm formation on a surface prone to such formation, wherein the rate of application of bromine-based biocide ( s ) is varied over the treatment , such that switching to a low dosing level of brominebased biocide ( s ) is accompanied by addition of the additive as herein defined to the water stream .

The present invention is particularly directed to provide microbial control over any microorganism known in the art , in particular any microorganism known to establish biofilm .

The present invention is particularly directed to provide microbial control over bacteria, e . g . Pseudomonas aeruginosa, Staphyl ococcus aureus, Bacill us mycoides , Candida albi cans , Aspergill us niger, and any combinations thereof and/or of microorganisms (namely bacteria, fungi or protists ) growing in mixed-species communities , for example in industrial or environmental water sources .

Figure 1 schematically illustrates one convenient method to feed a bromine-based biocide ("Bromine biocide" ) and the additive of the invention ("Additive" ) into an industrial water system . The water stream that comes in contact with a biofilm surface or a surface prone to biofilm formation is indicated by numeral ( 1 ) . The term " industrial water" is used to indicate any aquatic industrial water treatable by the methods of the invention, for example , recirculating and once-through cooling systems , cooling towers , pulp and paper mill systems , membranes , oil & gas applications, including biodiesel and diesel, floating production storage and offloading (FPSO) systems, sulphate reduction units (SRU) , steel mills, sugar & ethanol production, dairy production, swimming pools and spas, water distribution systems, irrigation systems, air washers, evaporative condensers, scrubbing systems, brewery pasteurizers, decorative fountains and oil recovery injection water.

It is seen that in the specific design illustrated in Figure 1, the biocide and the additive are held separately in tanks (2) and (3) , respectively, with their supply to the industrial water stream (i.e. the channel allowing water flow) being accomplished by using two dosing pumps (2p and 3p) . The design enables either sequential or simultaneous application of the two active components .

Biocides which fit well into the method shown in Figure 1 are biocides which are applied as a single pumpable formulation, for example, non-oxidizing biocides available in the marketplace as storage stable liquid formulations, e.g., concentrated bronopol and DBNPA solutions (e.g., 5 to 50 wt% concentrates) , and stabilized solutions of bromine or hypobromite (e.g., sulfamate- stabilized bromine-based biocide) .

The design shown in Figure 1 can be modified to enable the use of hypobromite-based biocidal solutions prepared on-site by oxidizing the bromide source just prior to use (these solutions must be applied immediately due to the instability of the hypobromite) , by installing a third feed system into the process (i.e., one dosing pump is dedicated for supplying the additive and two dosing pumps are used for the individual components of the biocide, i.e., the bromide source and the oxidant) . Incorporation of the additive as herein defined into water treatments where the bromine based-biocide is applied in solid forms such as granules or tablets ( fed to the inflow water line through erosion feeders ) could be achieved by inj ecting the additive solution with the aid of a dosing pump to the water line or to a subsidiary water stream diverted from the main stream into the feeder to dissolve the added solids .

The biocide and the additive solutions are dosed with metering pumps (2p and 3p, respectively) controlled by timers set up according to the treatment program . The biocide and the additive feed solutions may be inj ected directly to the water stream ( 1 ) but premixing of the two individual solutions in a mixing chamber (not shown) and delivery of the combined solution to the water stream is also possible to enable a treatment program based on simultaneous application of the two components of the treatment . To better control the treatment , monitoring and upstream mixing ( 4 ) devices are optionally included, namely, halogen monitoring, oxidation reduction potential ( ORP ) , pH sensors and online static mixers .

Regardless of the exact design, the separately supplied additive can be applied neat or dissolved in a water miscible solvent or mixture of solvents such as aliphatic alcohols up to 4 carbons , tert-butyl methyl ether, tetrahydrofuran ( THF) , dimethyl sul foxide ( DMSO) , glycols and polyethylene glycols , acetonitrile , optionally in the presence o f surfactants and stabili zers .

In operation, sequential treatment with the additive can be performed by inj ecting the additive from 20 minutes to 24 hours or more , prior to the biocide application . The additive may also be added following the biocide application to enhance the activity of the residual biocide in a water sample any time over the period of time that the active biocide is present in a system. Furthermore, the additive may be added simultaneously with the biocide application to the water (e.g. using a single feed solution as detailed below) .

Thus, the invention relates to a method wherein the brominebased biocide (s) and the fatty acid additive or a salt thereof are supplied to an industrial water stream in contact with an infested surface using multiple feed solutions, whereby the biocide and fatty acid additive are added sequentially or simultaneously to the water.

The additives as herein defined are compatible with either a non-oxidizing bromine-based biocide (e.g. DBNPA) or oxidizing bromine-based biocide (e.g. BCDMH) .

The method of the invention does not necessarily require multiple feeds as shown in Figure 1. Accordingly, the invention also provides a method wherein the bromine-based biocide (s) and additive are supplied to an industrial water stream in contact with an infested surface using a single feed solution, whereby the biocide and additive are added simultaneously to the water. Thus, the invention relates to a composition comprising one or more bromine-based biocides and an additive or a salt thereof (e.g., for use in the method) .

For example, a non-oxidizing bromine-based biocide and the additive of the invention may be formulated in a liquid concentrate, which is supplied to the industrial water stream using a single feed solution.

The liquid concentrates of the present invention comprise: a suitably proportioned mixture of (one or more) non-oxidizing bromine-based biocide (s) and the additive of the invention (or a salt thereof) , e.g., at a weight ratio from 1000:1 to 20:1, preferably from 500:1 to 20:1, e.g., from 250:1 to 20:1, such that on dilution in an industrial water stream the two active components are applied at an effective ratio; for example, in the liquid concentrate, the concentration of the biocide is from 2 to 50%, preferably from 10 to 50% and the concentration of the additive is from 0.05 to 2%, preferably from 0.1 to 1.0% (by weight based on the total weight of the liquid concentrate) ; and a carrier comprising water, water miscible solvent or a mixture thereof (i.e., water alone, organic solvent alone or aqueous/organic solvent system) ; and optionally one or more of the following components: cosolvents (e.g., glycols in which the nonoxidizing bromine-based biocide exhibits high stability and solubility, such as ethylene glycol, propylene glycol, or dipropylene glycol monomethylether) , antifreezes and stabilizers (e.g., an antioxidant, e.g. butylated hydroxytoluene) .

The concentrates are readily prepared by combining the additive of the invention, the non-oxidizing bromine-based biocide in a solid form, the glycol, water and the stabilizer under stirring at room temperature to obtain a clear solution.

Examples

Materials

Brominated biocides which are suitable for use in the present invention and reagents needed for activation are tabulated in Table 4 .

Table 4

active biocide

Methods

CDC Biofilm Reactor

The Centers for Disease Control and Prevention ( CDC ) Biofilm Reactor was used in the assays described herein below . Briefly, the CDC Biofilm Reactor is a continuously stirred tank reactor ( CSTR) with a high wall shear . This reactor was used for growing a reproducible Pseudomonas aeruginosa biofilm . The biofilm was established by operating the reactor in batch mode (without nutrients flow) for 4 hours. A steady state population was reached while the reactor operated for an additional 72 hours, with continuous flow of the nutrients. During the entire time, the biofilm was exposed to a continuous fluid shear from the rotation of a baffled stir bar. At the end of the 72 hours period, biofilm accumulation was quantified by removal of coupons from the suspended rods, harvesting the biofilm from the coupon surface, disaggregating the clumps, and diluting and plating the microorganisms for viable cell enumeration.

The Single Tube Method

The Single Tube Method was used to evaluate the efficacy of the agents used against the Pseudomonas aeruginosa biofilm grown in the CDC Biofilm Reactor. Briefly, the single tube method consists of adding a disinf ectant/dispersant or a control buffer (untreated) to individual coupons held in 50-mL conical tubes.

A neutralizer is added to the tubes after the appropriate contact time. A combination of vortexing and sonication is then used to remove the biofilm from the coupon and for disaggregating the clumps. Finally, the cell suspension is serially diluted and plated on agar medium.

Preparation 1

Biocide preparation by activation of HBr/urea solution

Stock solution 1 - 8.94 g of Bactebrom® from ICL-IP (HBr : urea solution) diluted with 241.06 g of distilled water.

Stock solution 2 - NaOCl ~1% prepared by 23.58g of NaOCl 10.6% w/w diluted with 226.42 g of distilled-water .

Stock solution 2 (250.00 g of NaOCl 1.0%) was added gradually while stirring to the above diluted Bactebrom® solution (stock solution 1) , to get the active biocide (orange solution) - total weight 500.00g. Expected biocide concentration as determined by iodometric titration using Titroprocessor : Titrino 848 plus. : ~ 0.5% as CI2 (~5000 ppm as CI2) . Desired biocide concentrations can be obtained by dilution with distilled water.

Preparation 2

Biocide preparation by activation of ammonium bromide

975 pl 10.25 Wt% aq. NaOCl was diluted with distilled water to 100 ml in a volumetric flask. CI2 concentration was ~1000ppm as CI2 as determined by iodometric titration using Titroprocessor: Titrino 848 plus.

213 mg NJhBr was diluted with distilled water to 100 ml in a volumetric flask.

Mix equal volumes of 5 ml as follows: add the NaOCl solution in one stroke to a mixed solution (using a magnetic stirrer) of the NJhBr solution at ambient temperature.

The concentration of the product (activated AmBr) was based on the concentration of the Na- Hypochlorite (~1000 ppm as CI2) . Equal volumes of the reactants were mixed to obtain the concentration of the active chlorine in the mixture as 50% of the concentration of the reactant NaOCl, ~500 ppm as CI2. Desired biocide concentrations can be obtained by dilution with distilled water. Example 1

Enhancing the effect of a bromine-based biocide on massive biofilm with the aid of Omega 3 fatty acids (sequential application)

The effect of bromine-containing biocides in combination with Omega 3 fatty acids on pre-grown biofilms was studied, by a sequential application of the fatty acids and biocidal agents, as detailed below.

Experimental procedure:

Biofilms were grown using the CDC Biofilm Reactor, as detailed above, utilizing the Pseudomonas aeruginosa strain ATCC 700888. Next, the Single Tube Method described above was used to evaluate the efficacy of the agents used against the Pseudomonas aeruginosa biofilm. The single tube experiment was carried out by first adding the fatty acids solution to the tube, at a concentration of 310 nM, for one hour. After one hour the coupon was moved to a second tube, containing a biocide solution in the desired concentration.

The fatty acid solution was a fish oil composition (Omega-3 600 mg fish oil capsules, Supherb, Noff Hagalil, Israel) containing a fatty acid composition of: 30% ERA (Eicosapentaenoic acid - 20:5) : 30% DHA (Docosahexaenoic acid - 22:6) 10% other Omega-3 fatty acids.

The bromine-based biocides tested in this study were 2,2- dibromo-3-nitrilopropionamide (DBNPA, at 10 mg/L) and 1-bromo- 3-chloro-5, 5-dimethylhydantoin (BCDMH, at 2.5 or 5 mg/L) . Results

Addition of Omega 3 solution to the biofilm cultures improved the ef ficacy of both of the biocides examined ( DBNPA, BCDMH) for biofilm removal , as detailed below .

The results of biofilm treatment with DBNPA in the absence or in the presence of Omega 3 are presented in Figure 2 . Figure 2 is a bar graph showing that the biocide DBNPA ( 10 mg/L ) when applied alone , reduced the total count of bacteria in the biofilm by about two log units . However, by adding Omega 3 at a concentration of 310 nM for 1 hour prior to the addition of DBNPA, the total count reduction improved by 3 . 5 log units .

Furthermore , the results of biofilm treatment with BCDMH in the absence or in the presence of Omega 3 are presented in Figure 3 . Figure 3 is a bar graph showing that BCDMH ( 5 mg/L ) reduced the total count of bacteria in the biofilm by about one log unit . However, by adding Omega 3 at a concentration of 310 nM for 1 hour prior to the addition of BCDMH ( 5 mg/L ) , the total count reduction improved by 3 . 5 log units .

Example 2 Enhancing the effect of a bromine-based biocide on massive biofilm with the aid of Jojoba fatty acids (sequential application)

The inventors have next examined the ef fect of fatty acids derived from Joj oba in improving the ef ficacy of various biocides in biofilm removal and prevention, as detailed below .

Experimental procedure :

Biofilms were grown using the CDC Biofilm Reactor, as detailed above , utili zing the Pseudomonas aeruginosa strain ATCC 700888 . Next , the Single Tube Method detailed above was used to evaluate the ef ficacy of the agents used against the Pseudomonas aeruginosa biofilm . Specifically, the single tube experiments were performed by first adding the fatty acids solution to the tube in the desired concentration for one hour. After one hour the coupon was moved to a second tube containing a biocide solution in the desired concentration, for an additional incubation of 1 hour.

Jojoba fatty acids were obtained by the hydrolysis of Jojoba oil with an alcoholic (methanol, ethanol and 2-propanol) solution of KOH followed by acidification. The general structure of the jojoba fatty acids used herein is as follows:

CH₃- (CH₂) 7-CH=CH- (CH₂) m-COOH where m=7, 9, 11 or 13.

The bromine-based biocide tested in this study was l-bromo-3- chloro-5, 5-dimethylhydantoin (BCDMH, at 5 or 10 mg/L) .

Results

Fatty acids derived from Jojoba were shown to improve the efficacy of BCDMH for biofilm removal:

Figure 4 is a bar graph showing that 10 mg/L of BCDMH reduced the total count of bacteria in the biofilm by 2.5-3 log units. Surprisingly, by adding Jojoba-derived fatty acids ("Jojoba") at a concentration as low as 310 nM for 1 hour before the addition of the biocide, the total count reduction improved by seven (7) log units. Similar synergistic results were obtained for a preaddition of Jojoba-derived fatty acids at higher concentrations (i.e. 3100 and 31,000 nM) .

Figure 5 is a bar graph showing that 5 mg/L of BCDMH reduced the total count of bacteria in the biofilm by two (2) log units. In this case as well, addition of Jojoba-derived fatty acids ("Jojoba") at a concentration of 310 nM for 1 hour before adding the biocide improved the total count reduction by seven (7) log units .

Claims

26

Claims

1) A method of microbial control in water comprising adding to the water one or more bromine-based biocide (s) and at least one fatty acid additive or a salt thereof (other than monounsaturated fatty acids in which the carbon-carbon double bond is at position

2) .

2) A method according to claim 1, wherein the microbial control comprises combatting planktonic bacteria and/or biofilm bacteria on a surface in contact with the water and/or inhibiting biofilm formation on a surface prone to biofilm growth.

3) A method according to any one of claims 1 or 2, wherein the bromine-based biocide is a non-oxidizing biocide.

4) A method according to claim 3, wherein the non-oxidizing bromine-based biocide is selected from the group consisting of: 2 , 2-dibromo-3-nitrilopropionamide (DBNPA) ; and 2-bromo-2-nitro-l , 3-propanediol (Bronopol) .

5) A method according to any one of claims 1 or 2, wherein the bromine-based biocide is an oxidizing biocide.

6) A method according to claim 5, wherein the oxidizing brominebased biocide is 1 , 3-dihalo-5, 5-dialkylhydantoin, wherein at least one of the halogen atoms is bromine, and the alkyl groups may be the same or different.

7) A method according to claim 6, wherein the 1 , 3-dihalo-5, 5- dialkylhydantoin is selected from the group consisting of l-bromo-3-chloro-5, 5-dimethylhydantoin (BCDMH) , l-chloro-3- bromo-5, 5-dimethylhydantoin, 1, 3-dibromo-5, 5-dimethylhydantoin and l-bromo-3-chloro-methylethylhydantoin, or mixtures thereof. 8) A method according to claim 5, wherein the oxidizing brominebased biocide is an on-site oxidized bromide source, which releases active bromine species in water.

9) A method according to claim 8, wherein the on-site oxidized bromide source is selected from the group consisting of: sodium bromide, which is oxidized on-site with hypochlorite, chlorine, hydrogen peroxide, ozone or electrochemically to produce its active form, to be added to the water system to be treated;

HBr, which is oxidized on-site with hypochlorite, chlorine, hydrogen peroxide, ozone or electrochemically to produce its active form, to be added to the water system to be treated; ammonium bromide, which is oxidized on-site with hypochlorite, chlorine, hydrogen peroxide, ozone or electrochemically to produce its active form, to be added to the water system to be treated; and solution of HBr/NaBr and urea, which reacts with hypochlorite, chlorine, hydrogen peroxide, ozone or electrochemically on-site to produce the bromourea active form, to be added to the water system to be treated.

10) A method according to any one of the preceding claims, wherein the bromine-based biocide (s) is added in an effective microbiocidal dosage of from 0.2 to 100 ppm and the additive is added in an enhancement-inducing amount of from 0.005 to 0.5 ppm.

11) The method according to any one of the preceding claims, wherein the additive comprises an unsaturated fatty acid.

12) The method according to claim 11, wherein the unsaturated fatty is Gondoic acid, Erucic acid, Oleic acid, Eicosapentaenoic acid (EPA) , or Docosahexaenoic acid (DHA) or a combination thereof .

13) The method according to claim 11, wherein the unsaturated fatty is at least one fatty acid derived from jojoba or an Omega 3 fatty acid or a combination thereof.

14) A method according to claim 12 or 13, wherein the brominebased biocide is l-bromo-3-chloro-5, 5-dimethylhydantoin (BCDMH) or 2 , 2-dibromo-3-nitrilopropionamide (DBNPA) .

15) A method according to 14, wherein: the bromine-based biocide is l-bromo-3-chloro-5, 5- dimethylhydantoin (BCDMH) ; and the additive is a mixture comprising from 10 to 70 wt . % Gondoic acid, from 10 to 70 wt . % Erucic acid and from 10 to 70% wt . % Oleic acid, or salts thereof, relative to the total weight of the additive.

16) A method according to claim 14, wherein: the bromine-based biocide is l-bromo-3-chloro-5, 5- dimethylhydantoin (BCDMH) or 2 , 2-dibromo-3-nitrilopropionamide (DBNPA) ; and the additive is a mixture comprising Eicosapentaenoic acid and from Docosahexaenoic acid at weight ratio from 1:2 to 2:1.

17) A method according to any one of the preceding claims, comprising combatting biofilm bacteria by adding to the water an effective microbiocidal dosage of the bromine-based biocide (s) and an enhancement-inducing amount of the additive to achieve biofilm reduction which is at least 1.5 log units higher than the log reduction achieved with the same dosage of the biocide acting alone. 29

18 ) A method according to any one of the preceding claims , wherein the bromine-based biocide ( s ) and the fatty acid additive or a salt thereof are supplied to an industrial water stream in contact with an infested surface using multiple feed solutions , whereby the biocide and fatty acid additive are added sequentially or simultaneously to the water .

19 ) A method according to any one of the preceding claims , wherein the bromine-based biocide ( s ) and the fatty acid additive or a salt thereof are supplied to an industrial water stream in contact with an infested surface using a single feed solution, whereby the biocide and CDA are added simultaneously to the water .

20 ) A composition comprising one or more bromine-based biocide ( s ) and at least one fatty acid ( other than monounsaturated fatty acids in which the carbon-carbon double bond is at position 2 ) or a salt thereof .

21 ) A composition according to claim 20 , which is a liquid concentrate comprising one or more bromine-based biocides and one or more fatty acids in a carrier , said carrier comprising water, water miscible solvent or a mixture thereof and optionally one or more of cosolvent ( s ) , anti freeze ( s ) and stabili zer ( s ) .