MXPA01002470A - Method of controlling biofouling in aqueous media using antimicrobial emulsions - Google Patents

Abstract

A method is disclosed for controlling biofouling in an aqueous medium by treating the aqueous medium with an oil-in-water emulsion comprising an antimicrobial oil phase and at least one emulsifier.

Description

METHOD FOR MONITORING THE BIOH INCRUTATION IN AQUEOUS MEDIA USING EMULSIONS ANT I MI CROB I NAS BACKGROUND AND FIELD OF THE INVENTION The control of b i or inc r us t a tion is an indispensable and complicated part of the industrial water treatment because biofouling can cause accumulation of heat transfer resistance, increase of system pressure, initiation and propagation of corrosion or oxidation. In an industrial water system, biofouling includes the formation of a biofilm, that is, an adherent colony of immobile microorganisms on a surface. The biopelícu s become a source of cellular aggregates in the volumetric solution through the events of discarding which can be activated by any of the environmental changes such as temperature, drag force, additions of nutrient and insecticide. The cellular aggregates represent a source of microbial inoculation in a system and potential obturation when coalescing the aggregates d i pe r s a do s. The REF. : 127926 Most abundant colony of microorganisms in industrial systems is either associated with biofilms or cellular aggregates which are discarded from biofilms. Therefore, the purpose of the biofouling control involves the removal of the existing biofilm, the disinfection of individual cells and cellular aggregates, and the prevention of regrowth of microorganisms in the treated system. Due to the higher density of bacteria and biopolymers within the biofilm and cell aggregates, a much higher concentration of insecticide is needed to achieve a desirable result. The current practice for microbial incrustation behavior in industrial water systems is the addition of control agents, especially oxidizing and non-oxidizing insecticides, to the volumetric water flow. For control agents to reach the biofilm, they have to rely on mass transport, that is, diffusion or convection. Once the agents reach the biofilm, their concentrations are in a very diluted form, so that they do not have enough power or persistence-to provide adequate disinfection. Therefore, in practice, most biofouling control agents are either wasted by the removal in the cooling tower, in the purge or consumed by reactions in the volumetric water. One proposal which has been taken to improve the supply of biocides to deal with the growth of the biofilm on the surfaces, is the encapsulation of insecticides used in the coatings before the use. This proposal has been implemented in marine applications, such as in U.S. Patent No. 4,253,877. However, this type of coating proposal is not practical for most water systems because once the initial coating has worn out, it is almost impossible to achieve a subsequent coating. The American Patent 'No. 4,561,981 describes the use of my chemical and specific gravity to administer chemicals to n t i i n c r u s t a c t ion for application in oil production. Similar proposals have been made for the production of paper, such as in U.S. Patent No. 5,164,096. These encapsulation proposals have also been used by the pharmaceutical and agricultural industries totally extensively for goal management and controlled release. Unfortunately, encapsulation has a greater disadvantage since it is difficult to prepare and the cost is prohibitive for industrial water treatment applications. U.S. Patent No. 4,954,338 teaches another proposal which uses a microemulsion as an insecticide carrier. However, the microemulsion is mainly used to solubilize an active ingredient of very low solubility in water and does not end at a specific surface. However, the active insecticide used in the formulation, ie a chlorinated octyl isothiazolone of low solubility in water, is more effective as a fungicide and algacide than a microbiocide, so this application has been limited for fungal and algae control.

Emulsions and microemulsions have been used as a way to formulate surfactants and oil-based solvents as cleaners / degreasers, such as in U.S. Patent Nos. 5,080,831 and 5,585,341. U.S. Patent No. 5,656,177 makes use of this property and describes an oil-in-water emulsion free of toxic microbicides for the prevention of biofouling, particularly in paper production processes. However, although this type of emulsion may be effective to some degree for some time, the non-toxic hydrophobic oil is a nutrient for some microorganisms and will eventually promote a selective type of biofouling. Accordingly, it may be desirable to provide a method for controlling biofouling in aqueous media more efficiently by specifically selecting the treatment chemicals directly from biofilms, cell surfaces and / or cell aggregates in a concentrated form. By targeting the surfaces of interest, the most efficient use of antimicrobial treatment chemicals can be made, thus providing an economically and environmentally acceptable use of the insecticides.

BRIEF DESCRIPTION OF THE INVENTION The method of the invention aims at the treatment of an aqueous medium with an oil-in-water emulsion comprising a microbial oily phase and at least one emu 1 f i s i cant e. This treatment method efficiently and effectively controls biofouling in the aqueous medium, specifically by selecting biofilms, cell surfaces and / or cell aggregates. The treatment method is also economically and environmentally acceptable because the use of insecticides is minimized.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of control of biofouling in an aqueous medium. In accordance with this invention, the aqueous medium is treated with an oil-in-water emulsion comprising an antimicrobial oily phase and at least one emulsifier. In one embodiment of this invention, the microbial oily phase is a nonaqueous liquid phase ioincrustation control agent. The non-aqueous, liquid phase biofouling control agents which may be used include, but are not limited to, phenoxytol propanol, pe nt ac 1 gold pheno 1,5-chloro-2- (di chloro or phenoxy) phenol, 1 - (2-Hydroxy-1) -2-a-1-i-1 (Cis) -2-imi-zo-1-one, aliphatic acids of 8 to 20 carbon atoms, -aliphatic alcohols of 8 to 20 carbon atoms and aliphatic amines of 8 to 20 carbon atoms. In another embodiment of the invention, the microbial oily phase is a non-aqueous liquid phase and a biofouling control agent, wherein the biofouling control agent is soluble in the non-aqueous liquid phase. Suitable non-aqueous liquid phases include, but are not limited to, aliphatic alcohols of 4 to 30 carbon atoms such as octanol, decanol and dodecanol; saturated hydrocarbons of 4 to 30 carbon atoms such as decane, hexane, octadecane and dodecane; monosaturated hydrocarbons of 4 to 30 carbon atoms such as decene and hexadecene; natural oils such as palm, corn, coconut and soybean oils; and mineral oil paraffins. Biofouling control agents which can be used according to this embodiment of the invention include, but are not limited to, any antimicrobial control agent which can be divided into the non-aqueous liquid phase such as glutaraldehyde, 2, 2 -dibromo-3-nitrilopropionamide, isothiazolone, methylenebistiocyanate, 2-bromo-2-nitropropan-l, 3-diol, 2- (thiocyanomethylthio) benzothiazole, bi s (tricoror orne ti 1) sulphon, 5-c 1 or o- 2 - (2, 4 -di c 1 or of enox i) f ene 1, ortho phenylphenol, bromo-nitro-et en i 1-furan, br omon itr oe stire no, tribuine oxide 1 this year and 2 -me ti 1 - 4, 5 - tr ime ti 1 en - 4 - isothiazo 1 in - 3 - on a. The biofouling control agent can also be a chelating agent, such as ethylenediamine tetraacetic acid (EDTA), eti 1 in g 1 ico 1 -bis (b-amyloe thi 1 o) tetraacetic ether ( by its acronym in English, EGTA) and 8 - hi dr ox i qu i no 1 ina.

One reason for the use of chelating agents and selection of them in the biofilm is because of that. chelating agents can extract cationic ions from the biofilm in which cationic ions, such as calcium, are known to cross-link extracellular polymers. Many of the chelating agents are also known to be toxic to microorganisms causing loss of cell membrane and denaturation of the protein. Oil-in-water emulsions which can be used in the practice of this invention include my oil in water, my oil and water mixtures and mixtures of these. Emulsifiers that can be used according to the invention include anionic, cationic, nonionic or amphoteric surfactants. Suitable anionic surfactants include alkyl sulfates having the formula: R-S03 M, wherein R is any alkylaryl or fatty alkyl group and M is a counterion, such as Na +, NH ', Mg ++ or triethanolamine; ether sulfates having the formula: RO- (CH2CH20) nS03M wherein R is any alkylaryl or fatty alkyl group and M is a counterion such as, Na +, NH + 4, Mg ++ or triethanolamine, and n is the number of moles of ethylene; dodecylbenzene sulfonate, alpha olefin sulfonate, diphenyloxide disulfonate, alkyl naphthalene sulphonate, sulfosuccinate, sulphosuccinate, condensate of naphthalene aldehyde, sulphoester, sulfoamide, esters of alkyl phosphate and alkyl ether carboxylate. The cationic surfactants which may be used include imidazoles, dialkyl quaternary ammonium chlorides. dialkyl benzyl quaternary ammonium chlorides, amine oxides and ethoxylated amines. Suitable non-ionic or non-ionic compounds include 1 to 1 amides, ethoxylated alkanolamide, ethylene bisamide, fatty acid esters, glycerol esters, sorbitan esters, ethoxylated fatty acids, ethoxylated glycol esters, esters of po 1 ieti 1 e ng 11 co 1, ethoxylated sorbitan esters, ethoxylated alkylphenol, ethoxylated alcohol, ethoxylated tristri 1 pheno 1, ethoxylated mercaptan, alkoxylated alcohol, block copolymer (EO / PO) and eti 1 oxide in o / ox propylene, inverted and ethoxylated copolymer topped with chlorine. Amphoteric surfactants which may be used include ina imidaz mono acetate, imidazine dipropionate, amphoteric imidazole sulfonate, alkyl betaine, sultaine, dihydroxyethyl glycinate, alkyl amidopropropyl betaine and aminopropionate. It is preferred that the amount of the oil in water emulsion which is used to treat the aqueous medium be in the range of about 1 to about 2000 parts per million (ppm). More preferably, the amount of oil-in-water emulsion used to treat the aqueous medium is in the range of about 5 to about 500 ppm, with about 10 to 100 ppm being more preferred. Preferably, the oil-in-water emulsion comprises from about 1 to about 70% by weight of the antimicrobial oily phase and from about 1 to about 25% by weight of the emulsifier, the equilibrium of the emulsion is water. The oil-in-water emulsion can be metered into the aqueous medium either dosed in a stationary manner or on a continuous basis. In one embodiment of this invention, where the antimicrobial oily phase is a non-aqueous liquid phase biofouling control agent, the emulsion is prepared by dissolving the emulsifiers in either water or the antimicrobial oily phase depending on their solubility. The water-soluble emulsifiers are dissolved in water and the insoluble emulsifiers are dissolved in the oily phase. The oily phase and aqueous phase solutions are then mechanically mixed with a device such as a homogenizer or mixer to form an emulsion. In another embodiment of the invention, wherein the antiracrobial oily phase is a non-aqueous liquid phase and a biofouling control agent, the solution is dissolved in the non-aqueous liquid to form an oily antimicrobial phase solution. The emulsifiers are dissolved either in water or in the antimicrobial oily phase depending on their solubility. The water-soluble emulsifiers are dissolved in water and the insoluble emulsifiers are dissolved in the oily phase. The oily phase and aqueous phase solutions are then mechanically mixed with a device such as a homogenizer or mixer to form an emulsion. For the purpose of controlling the dosage of the product and the tracing of the assets, a very small amount (less than 1% by weight of the emulsion) of an inert oil-based dye or a fluorochrome stain, can optionally be formulated in the emulsion As used herein, the term "inert" means that the dye or stain does not react with the other ingredients of the emulsion or lose or change its fluorescent properties or color. The dye or stain should be soluble in oil, have very low solubility in water, and different fluorescent emission properties or not be in the aqueous phase. Examples of the type of dyes and stains which may be used include octadecyl rhodamine B, acylaminofluoresceins, diphenylhextriene, Nile Red, and Sudan IV (available from Aldrich). The concentration of the oil-in-water emulsion in the volumetric liquid phase can then be detected online or off-line afterwards, which is dosed into the water system by either colorimetric methods or fluorescent methods. The change in the indicator concentration in the volume will indirectly indicate the speed of active consumption or adsorption of the surface. When access to surfaces is possible, the concentration of the chemical treatment that reaches and adsorbs to the surface could also be directly detected with reflective surface colorimetry when using colored dyes such as fluorometry methods or Sudan IV when using compounds fluorescent such as Nile Red. It is understood that when a fluorometer is used to detect the fluorescent signal of the oil-base fluorochrome stain, the excitation and emission filters of the fluorometer must be adjusted to detect the appropriate signal from the selected fluorochrome stain. The method of the present invention can be used to control biofouling in an aqueous medium such as an industrial water system. Typical industrial water systems include those in pulp and paper mills, open recirculation cooling water systems, cooling ponds, dams, freshwater applications, decorative fountains, greenhouses, evaporation condensers. , hydrostatic stabilizers and retorts, gas scrubbing systems and air washing systems. The inventive method can also be used in another aqueous medium, such as in oil and gas production processes, food and beverage processes, recreational water and the like. Treating an aqueous medium with an oil-in-water emulsion comprising an antimicrobial oil phase and at least one emulsifier that efficiently and effectively controls bioincrusion by biofilms directed specifically to an objective, cell surfaces and / or cell aggregates. ' With respect to biofilms and cell aggregates, it will be noted that the control with the applications of insecticides with encionales is relatively useless because the dilution of the active ingredient is very high, so that the microorganisms are protected from the effects of the agent antimicrobial The oil-in-water emulsions described herein provide means to overcome the protection of derived microorganisms from being in suspended cell aggregates and in biofilms by supplying microscopic particles containing highly concentrated active ingredient (percentage level) directly on the surface of the cellular aggregate or biofilm The oil-in-water emulsions of the present invention also exhibit several important attributes, mainly those that protect the active ingredient from contaminants which must be present in the aqueous medium, they rapidly exterminate microorganisms independent of pH changes, they have an affinity for biofilms and cell surfaces, and they exhibit a release controlled antimicrobial agents for cell surfaces.

EXAMPLES The following examples are proposed to be illustrative of the present invention and teach someone of ordinary experience how to make and use the invention. These examples are not proposed to limit the invention or its protection in any way. E n g lish 1 Microemulsion of Fenoxitol Propanol The microemulsion of phenoxytol propanol (PPh) is commonly used as an organic solvent. However, PPh also has biocide activity. (See "Microbicides for the Protection of Materials," Wilfried Paulus, lera ed., 1993, Chapman &Hall.) The oil-in-water microemulsion of PPh can be formed spontaneously by mixing appropriate amounts of water, PPh, dodecyl lbensns or sodium 1 -sodium (SDBS), and sodium xylene sulfonate. The PPh microemulsion formulations are listed below in Table 1. The values in the table represent fractions by weight.

Table 1 The formulation effect # 1 in the biofilm removal was tested in a laboratory tubular biofilm reactor. The culture biofilm mixed with chilled water was grown under a flow rate of 3 ft / sec (91.44 cm / s) on a polyvinyl chloride (PVC) pipe surface. The thickness of the biofilm tested was approximately 100 μ. The change in thickness of the biofilm was observed continuously with a differential pressure transducer through a set of 1/8"(0.3175 cm) pipe ID, 16 feet (487.68 cm), in length. significant biofilm (> 70%) was observed with continuous PPh microemulsion treatment for 8 hours.The results of the biofilm treatment are summarized in Table 2 below. The dosage of the treatment used was 600 ppm as PPh. After the product tracking, a small amount of oil-soluble ink (O.lg Sudan IV per microemulsion Oml) was added to stain the microemulsion network during a study of samples of test material in which a biofilm sample was submerged in 600 ppm of PPh microemulsion solution, the red color was transferred from the liquid phase to the surface of the biofilm sample after a few hours. the PPh is absorbed in the biofilm.

Table 2 Colony forming unit A control experiment was also conducted by treating the biofilm with the same dose of the surfactant without PPh. The percentage of biofilm removal achieved was only 44 + 1%.

E n g l e 2 Glutaraldehyde emulsion DBNPA / Decanol The preparation of emulsions of g 1 u t a r a 1 dehi do / dean 1 first requires an extraction of 1 i qu / do. 30 ml of 50% by weight glutaraldehyde in water (Piror 850, available from Union Carbide) were mixed with 30 ml of 1-decanol. The mixture was stirred for 24 hours. The decanol was separated from the aqueous phase by gravity. The partition coefficient of glutaraldehyde for decanol / water is 1.26 (molar ratio). The glut solution for ldehyde / decanol was then used as the non-aqueous phase antimicrobial oil to generate emulsions. The dried 2,2-dibromo-3-nitroglyph opionamide (DBNPA) (98%) was directly solubilized in decanol (1.5 - 6.1% by weight). Then the decanol solution DBNPA was emu 1 s i f i c. The surfactants of the formulations in Table 3 were dissolved in water or decanol phase depending on their solubility. The two solutions were then mixed together using either homogenization or vortex treatment. Many of these emulsions show excellent stability for 9 months at room temperature. ro Lp cp o Table 3 Emulsion Formulations (% weight) Chemical Components A B C 0 E F G H 1 J K L Non-Aqueous Liquid Phase: 22 7 20 6 20.6 20.6 20.8 20.6 20.6 20.8 20.8 26.3 21 .6 - - - - - - 20.6 34.8 Surfactants: - • -? Ratainea 'ASC 5 2 16.7 5 2 5.2 5.2 Dowfax' "2A 1 5.2 10.8 4. 1 - - - - • - TWEEN '81 - - - - - 1.0 1.0 - - SPAN'" 40 - - - - - 4.3 - • Alkamuls 0- 14 - - - - - - 5.3 5.2 To the amuls * EL 985 - - - - - - 5.3 - 5.2 Alka uls * EL 620 - - • - - • - • 4.6 Arlatsne ™ G - - - - - - - - - - 4.6 Pluromc "1 P103 5.2 2.9 4.1 - - - - - Pluronic * L63 - • - - 5.2 5.2 10.3 - - • • 8.2 Pluronic * P65 • - 5.2 5.2 10.3 9.3 9.4 10.4 12.4 Water 61 .9 49.0 66.0 63.9 68.8 58.8 63.9 68.8 64.5 63.2 58.8 68.0 56.0 % Total 100 100 100 100 too 100 100 100 100 100 100 100 100 IPV * 26 7 22.2 24.1 24.1 24.2 24.2 24.1 24.2 24.2 30 24.2 25 30 * IPV = internal phase volume E j us 3 This experiment was conducted to evaluate the stability of the emulsion at 54 ° C and until dilution. The stability of the emulsion was evaluated by its appearance. An unstable emulsion is seen when the shake or separation of the phase exists. The emulsions J and L, prepared above in Example 2, where they were tested at 54 ° C in concentrated form. Emulsion J was tested at 25 ° C in two dilutions (1:10 and 1:20). None of the emulsions showed any shake or phase separations for 30 days.

Example 4 The release of glutaraldehyde from the decanol emulsions prepared in Example 2 was evaluated using dialysis technique at room temperature. 2 ml of concentrated emulsion containing glutaraldehyde were added in a cassette or dialysis case (Cellulose membrane with molecular weight limitation of 10,000, S 1 i of -A- Ly z e r, Pierce). The cassette or dialysis cassette was stirred in a beaker containing 450 ml of cooling water (pH 8.3). The glutaraldehyde was released into the dialysate (cooling water) from the emulsion during dialysis. The sample aliquots were taken from the dialysate. The concentration of glutaraldehyde remaining within the dialysis chamber was also determined at the end of the experiment. The analyzes of glutaraldehyde in both the dialyzate and the products of the concentrated emulsion were carried out using both gas chromatography and colorimetric methods. Colorimetric analyzes were performed on the complex hydrazone 3-methyl-2-ben z otiazole and nona glutaraldehyde (MBTH), which was formed after heating in boiling water for 5 minutes (See Freid, et al., 1991 , CORROSION / 91, paper # 202, NACE Annual Conference, March 11-15, Cincinnati, OH). The percentages of glutaraldehyde released are listed below in Table 4. As illustrated in the table, emulsions I, J, and L demonstrated slow release of the mi c c o n t i c t in the cooling water.

Table 4 the glutaraldehyde solution was prepared from the concentrate P i r or r 50) E j emp lo 5 The Minimum Inhibitory Concentrations (MIC) tested were run for many of the emulsions formulated above in Example 2 and compared with glutaraldehyde alone. Both Gram-negative and Gram-positive microorganisms were tested. MIC tests were conducted on a minimum media of the following composition (g / L): 0.05 CaCl2; 0.2 MgSO4-7H20; 0.33 K2 H PO 4; 0.07 yeast extract and 2 glucose. The densities of the starting cells were 106 and 105 cells / ml. by Pseudomonas s Fluores cen s and Paen was ci 11 us macerans, respectively. The MIC tests were conducted on 96-well multiple plates and recorded after all the control wells became positive for growth. This usually takes 12-24 hours. The results shown later in Table 5 indicate that the emulsions have MIC values that are equivalent or slightly better than glutaraldehyde.

Table 5 The MIC results demonstrated that emulsions containing glutaraldehyde retain activity as antimicrobial agents. This is an important feature because some forms of my skin are so well encapsulated that the active ingredient becomes less active. This is also a surprising result because it is known in the literature that glutaraldehyde and primary alcohols such as decanol react to form acetals (See "Factors to Consider When Freeze-Proofing a Biocide," Douglas B. Mcllwaine, 1998, Materials Performance, 37 (9): 44-47.) Acétals have very small, if any, insecticidal efficacy.

E j empl o 6 Fluorescence microscopy was used to show the adsorption and absorption of emulsion particles to corroded metal surfaces, biofilms and bacterial cells. The emulsions were stained with the lipophilic fluorochrome, Nile Red (1 μg / ml), so that the binding of the emulsions to the surface of interest could be visually documented. The surfaces of interest (biofilms, cell surfaces and / or cell aggregates) were exposed to 1.0% solutions of stained emulsions (10 ng / mL of Nile Red) by short contact time of less than 1 minute and then vigorously rinsed prior to microscopic observation. Bacterial cells were exposed to emulsions for longer contact times of 24 hours. The binding of the emulsion particles were observed for all these substances under a fluorescent microscope.

E j empl o 7 This example was designed to determine the kill rate for glutaraldehyde and decanol emulsions compared to free glutaraldehyde, as well as the effects of pH on kill rate. The glutaraldehyde and the emulsion J of glutaraldehyde (prepared above in Example 2) were both dosed at concentrations of 50 ppm as glutaraldehyde. The decanol emulsion was prepared as described in Example 2 with the following composition in% by weight: 26 decanol, 5.3 Alkamuls 0-14, 5.3 Alkamuls EL-985 and 63.4 water. The decanol emulsion was diluted to the same order of magnitude as the glutaraldehyde emulsion (l, 680x, 150 ppm as decanol).

Cells washed with phosphate buffered saline (PBS) from the culture Ps e u dom on a s a u u u n a s were used as the target microorganisms. The time indicated for this study were 2, 10, 30 and 60 minutes. The effect of pH on the extermination rate was conducted in a similar manner. Only one contact time (10 minutes) was used for this study and the emulsions and glutaraldehyde were placed in 3 different pH, that is, 5, 7, and 10, just prior to the addition of the cells. The buffer solution consisted of acetic acid (0.04 M), phosphoric acid (0.04 M) and boric acid (0.04 M). The correct pH was obtained by the addition of NaOH. In both experiments, after each time indicated, the samples were taken and placed in the dilution tubes containing 300 ppm sulfite to deactivate any residual insecticide. Microbial enumerations were conducted with standard plate counts on solid medium of yeast extract agar (TGE), glucose, tryptone. Tables 6 and 7 show the results of these experiments. The emulsion compositions achieved a greater reduction of 3 Logio in the concentration of the viable bacterium after 8 minutes while the glutaraldehyde took 30 minutes to achieve a similar extermination (Table 6). After 10 minutes, only the emulsions were able to achieve an extermination at a pH of 5 and 7 with a reduction greater than 4 Logio in the concentration of viable bacteria at a pH of 5 (Table 7). In contrast, glutaraldehyde alone had a rapid kill rate at a pH of 10.

Table 6 CFU * / mL Log10 reduction (FCO / mL) T? Enpo (mm) Glutarally gone Glutaraldehyde Omission Biulsic J Jialtion of Glutaraldehyde Omission decanol glutaraldehyde decanol 2 6.2E + 06 2.0E + 04 8.0E + 03 0.0 2.5 2.9 8 3.5E + 06 1.0E + 02 1.0E + 03 0.2 4.8 3.8 5.0E + 04 1.0E + 01 1.0E + 02 2.1 5.8 4.8 5.0E + 02 1.0E + 01 1.0E + 02 4.1 5.8 4.8 60 1.0E + 02 1.0E + 01 1.0E + 02 4.8 5.8 4.8 6.2OE control + 06 * CFU = unit for colonies, measure the viable (live) bacterial cells in the sample.

T a b l a 7 CFU / ml Log10 (CFU / mL) Reduction PH 5 7 10 5 7 10 Control SE + 06 9E + 06 1E + 07 Glutaraldehyde 7E + 06 1E + 07 1E + 02 0.0 0.0 5.1 Emulsion J of Glutaraldehyde 1E + 02 1E + 05 1E + 02 4.7 1.8 5.1 Emulsion of Decanol 1E + 02 3E + 03 1E + 01 4.7 3.6 6.1 Example A problem commonly observed in water treatment is that when glutaraldehyde is used simultaneously with bromine-oxidizing biocides, there is a resulting loss of bromine residue observed. Thus, an experiment was designed to test the effect of emulsified glutaraldehyde on the loss of bromine oxidant residue. Six different treatments of bromine oxidant biocides plus 200 ppm as glutaraldehyde or without glutaraldehyde were added to beakers containing 500 ml of artificial cooling water. Each beaker was continuously stirred with a stir bar and samples were taken every 15 minutes for 1 hour and every 30 minutes thereafter up to 2 hours. The starting concentrations for total halogen residues for all six beakers vary from 5.5-6.5 ppm as Cl2. The method of N, N-diethyl-p-f-en-lendiamine (DPD) method (Standard Methods for the Examination of Water and Wastewater, 19th ed., Method 4500-C1 G) was used to observe the change of residual bromine. Glutaraldehyde was dosed in two different forms, mainly free glutaraldehyde and as the glutaraldehyde emulsion. The intermediate values were calculated from the residual halogen against the time data. Table 8 illustrates that the glutaraldehyde emulsion of this invention is less reactive and more compatible with bromine oxidant insecticides, especially the STABREX ™ product from Nalco Chemical Company, than with free glutaraldehyde. This attribute allows to improve the combined use of bromine products with glutaraldehyde. In this example, the average chemical bromine duration was more than double using STABREX ™, stabilized liquid bromine, and the glutaraldehyde F emulsion prepared in Example 2. This improved compatibility results in superior performance because the insecticide based in halogen and glutaraldehyde are not consumed quickly by the chemical reaction with each other.

Table 8 Half Life of Oxidizing Bromine (min.) Bromine + Glutaraldehyde 33 Bromine + Glutaraldehyde Emulsion F 40 STABREX ™ * + Glutaraldehyde 40 STABREX + Glutaraldehyde Emulsion F 71 Sodium hypobromite 319 STABREX 666 * STABREX - Nalco Chemical Company (US Patent No. 5, 683, 654) E j emp lo 9 Sulfite is frequently found as a contaminant in water treatment programs, either from the remaining pulp kraft bleaching process or as process contaminants in cooling water systems. Sulfite very quickly deactivates glutaraldehyde and DBNPA as an insecticide in less than 10 minutes and frequently the sulfite demand is overcome by adding additional insecticide. This is a costly way to overcome the demand for insecticide in a contaminated system. The experiments were conducted to consider the extent and prolongation of time in which glutaraldehyde and DBNPA could be stabilized or protected from sulphite deactivation. The separate tests were conducted with and without the addition of sulfite to artificial cooling water. The sulfite was added at a 3: 1 molar ratio for glutaraldehyde (3mM sulfite: lmM [100ppm] glutaraldehyde). The glutaraldehyde and glutaraldehyde emulsions were exposed to cooling water containing sulphite for 2 and 4 hours prior to the addition of 0.25 ml of washed, phosphate buffered cells. For the DBNPA emulsion deactivation experiments, 10 ppm as DBNPA was exposed to 50 ppm of sulfite for 1 hour prior to the addition of cells. The cells were then incubated for an additional 2 hours prior to the microbial enumerations. The total volume of the treatment fluid was 25 ml contained in disposable polystyrene test tubes. The standard plates considered were used to enumerate the colony forming units (CFU) / ml. The test with the emulsions of glutaraldehyde and DBNPA shows that these insecticides remain active in the presence of sulfite which deactivates free insecticides, as shown in Table 9. Because both insecticides were deactivated very quickly by sulfite, the data suggest that the emulsion particles deliver the active ingredient directly to cell surfaces instead of placing it back into the volumetric phase. which could deactivate the insecticides before the reaction with the cells.

Table 9 ogl0 (CFU / ml) Treatment CFU / ml Reduction Control, without treatment 1.6E + 7 Glutaraldehyde 1.0E + 1 6.2 Glutaraldehyde + S032- (lOmin.) * 3.3E + 7 0.0 Glutaraldehyde Emulsion F < 1.0E + 1 6.2 Glutaraldehyde Emulsion F + S032- (2hr.) 1.0E + 4 3.2 Glutaraldehyde Emulsion F + S032- (4hr.) 1.1E + 4 3.2 DBNPA < 1.0E + 1 6.5 DBNPA + S032- (10 mm.) 1.3E + 7 0.7 DBNPA Emulsion K 1.0E + 1 6.5 DBNPA Emulsion K + S032- (lhr.) 1.3E + 4 3.7 * Time represents the deactivation time prior to additions of icrobial cells E j emp lo 10 Waterborne pulps for papermaking frequently have sulphite transferred from bleaching processes or have sulfite deliberately added as oxidizing insecticide deactivating agents prior to ink additions. Broken containers are a frequent problem to find for microbial control in paper-making systems and non-oxidizing insecticides are frequently added to gain control in these systems. Decayed watery pastes may have high concentrations of facultative anaerobes as a result of poor microbial control. These anaerobes produce ferrous fatty acid fermentation products, that is, volatile fatty acids, which can impart undesirable odors and produce dangerous concentrations of organic gases. DBNPA emulsion K, prepared in Example 2, was tested against DBNPA for the microbial control of facultative anaerobes and acid-producing bacteria (APBs) in watered pulps decomposed to make paper with and without sulphite contamination. Decayed watery pastes coated from a paper bin were used for this study. Previous studies with this decomposing watered paste do not reveal residual toxicity when measured with Nalco's TRA-CIDE® technology and viable microbial counts of anaerobes were in the order of 107 CFU / ml. There was no residual sulfite in the decomposed sample, so that 52 μl of a 2.4% sulfite solution was added to 25 ml of decomposed slurry to achieve 50 ppm of final sulfite concentration in the slurries. The watery pastes were mixed well prior to the addition of DBNPA or DBNPA K emulsion. The control tests receive either DBNPA or DBNPA emulsion treatment, but without addition of sulfite, and another control does not receive treatment at all. The sample time indicated for all treatments was 0.5, 1 and 2 hours. The concentration of DBNPA as active was 10 ppm. The enumeration of facultative anaerobes was conducted on thioglycollate agar poured into plates and acid-producing bacteria in the APB medium using enumerations of most probable numbers (for its acronym in English MPN). The composition of the APB medium (g / L) was: 5.0 tpptona, 2.5 glucose, 0.5 NaCl, 1.0 K2HP04 and 0.015 Chlorophenol Red, pH adjusted to 7.0 with NaOH. The APB medium was recorded positive for growth when the pH indicator changes color from purple to yellow. As shown in Table 10, the results indicate improved performance using the DBNPA emulsion when sulphite occurs in decomposed slurries.

Teibla 10 APBs Anaerobic APBs Anaerobic MPN / m .1 CFU / ml Log10 Reductions Control 2.1E + 07 5.0E + 7 DBNPA + S03-2 0.5 hr. 1.2E + 07 2.4E + 7 0.2 0.3 1 hr. 7.9E + 07 0.0 2 hr. 8.0E + 06 5.0E + 7 0.4 0.0 DBNPA emulsion K + S03"2 0.5 hr 1.2E + 05 1.8E + 5 2.2 2.4 1 hr 3.7E + 05 5.6E + 4 1.7 3.0 2 hr 7.7E + 04 1.6E + 5 2.4 2.5 While the present invention was described above in connection with illustrative or preferred embodiments, these embodiments are not intended to be exhaustive or limiting of the invention. Of course, the invention is proposed to cover all alternatives, modifications and equivalents included within its spirit and scope as defined by the appended claims.

It is noted that in relation to this date the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (21)

1. A method for controlling biofouling in an aqueous medium characterized in that it comprises the step of treating the aqueous medium with an effective amount for controlling the biofouling of an oil in water emulsion comprising an oily antimicrobial phase and at least one emulsifier.

2. The method according to claim 1, characterized in that the antimicrobial oily phase is a non-aqueous liquid phase biofouling control agent.

3. The method according to claim 2, characterized in that the liquid phase, non-aqueous biofouling control agent is selected from the group consisting of phenoxytol propanol, pen tac 1 or of ene 1, 5-chloro-2- (dichlorophenoxy) phenol, 1- (2-hydroxy-1-yl) -2 -alkyl (cis) -2-imide zol ina, aliphatic acids of 8 to 20 carbon atoms, aliphatic alcohols of 8 to 20 carbon atoms and amines aliphatic from 8 to 20 carbon atoms.

4. The method according to claim 1, characterized in that the antimicrobial oily phase is a non-aqueous liquid phase and a biofouling control agent, wherein the biofouling control agent is soluble in the non-aqueous liquid phase.

5. The method according to claim 4, characterized in that the non-aqueous liquid phase is selected from the group consisting of aliphatic alcohols of 4 to 30 carbon atoms, saturated hydrocarbons of 4 to 30 carbon atoms, monosaurized hydrocarbons of 4 at 30 carbon atoms, paraffins of mineral oils and natural oils.

6. The method according to claim 4, characterized in that the biofouling control agent is selected from the group consisting of glutaraldehyde, 2,2-dibrino-3-nitro-roprop-onamide, isotia-1-one, methylenebisthiocyanate, -bromo-2-nitropropane-1,3-diol, 2- (thiocyanomethylthio) benzothiazole, bis (trichloromethyl) sulfone, 5-chloro-2- (2,4-di-chloro-phenoxy) -phene-1, ortho-phenylphenol, bromine -nitro-et en i 1-fu ran, bromoni t roes tir eno, tributyltin oxide, 2-methyl-4,5-trimethylene-4-isothiazo 1-3 -one and chelating agents.

7. The method according to claim 6, characterized in that the chelating agent is selected from the group consisting of ethylenediamine tetraacetic acid, ethylene glycolic acid, 1-bi s (b_-ami noe ti 1 e er) tetra acé ti co and 8 - hi dr ox i qu i no 1 i na.

8. The method according to claim 1, characterized in that the oil-in-water emulsion is selected from the group consisting of my cr emus 1 s i one s, • ma cr oemu 1 s i one s and mixtures thereof.

9. The method according to claim 1, characterized in that the emulsifier is selected from the group consisting of anionic, cationic, nonionic and amphoteric surfactants.

10. The method according to claim 9, characterized in that the anionic surfactant is selected from the group consisting of alkyl sulfates having the formula: R-S03 M, wherein R is an alkylaryl or fatty alkyl group and M is a counterion selected from the group consisting of Na +, NH + 4, Mg ++ and triethanolamine; ether sulfates having the formula: R-0- (CH2CH20) nS03M wherein R is an alkylaryl or fatty alkyl group and M is a counterion selected from the group consisting of Na +, NH + 4, Mg + + and triethanolamine , and n is the number of moles of ethylene oxide; dodecylbenzene sulfonate, alpha olefin sulphonate, diphenyloxide disulfonate, alkyl naphthalene sulphonate, sulfosuccinate, sulphosuccinate, condensate of naphthalene-ormaldehyde, sulphoester, sulfoamide, esters of alkyl phosphate and alkyl ether carboxylate.

11. The method according to claim 9, characterized in that the cationic surfactant is selected from the group consisting of zirconium imide, dialkyl quaternary ammonium chlorides, dialkyl benzyl quaternary ammonium chlorides, amine oxides and ethoxylated amines.

12. The method according to claim 9, characterized in that the nonionic surfactant is selected from the group consisting of 1 to 1 amide, ethoxylated alkanolamide, ethylene bisamide, fatty acid esters, glycerol esters, sorbitan esters , ethoxylated fatty acids, ethoxylated glycol esters, polyethylene glycol esters, ethoxylated sorbitan esters, ethoxylated alkylphenol, ethoxylated alcohol, ethoxylated phenol 1-phenol, ethoxylated mercaptan, alkoxylated alcohol, block copolymer (EO / PO) wood / propylene oxide, inverted and ethoxylated copolymer topped with chlorine.

13. The method according to claim 9, characterized in that the amphoteric surfactant is selected from the group consisting of imidazaline monoacetate, imidazaline dipropionate, amphoteric imidazaline sulfonate, alkyl betaine, sultaine, dihydroxy and glycinate, alkyl amine. dop r opropi 1 betaine and ami nopr op ona to.

14. The method according to claim 1, characterized in that the aqueous medium is treated with approximately 1 to approximately 2000 ppm of the oil in water emulsion.

15. The method according to claim 1, characterized in that the aqueous medium is treated with about 5 to about 500 ppm of the oil in water emulsion.

16. The method according to claim 1, characterized in that the aqueous medium is treated with approximately 10 to approximately 100 ppm of the oil in water emulsion.

17. The method according to claim 1, characterized in that the oil-in-water emulsion comprises from about 1 to about 70% by weight of the antimicrobial oily phase and from about 1 to about 25% by weight of the emulsifier.

18. The method according to claim 1, characterized in that the oil-in-water emulsion further comprises an inert oil-based dye.

19. The method according to claim 1, characterized in that the oil-in-water emulsion further comprises an oil-based fluorochrome stain.

20. The method according to claim 1, characterized in that the aqueous medium is an industrial water system.

21. A method of selecting biofilms and cell aggregates in an aqueous medium characterized in that it comprises the step of administering an oil in water emulsion comprising an antimicrobial oily phase and at least one emulsifier in the aqueous medium.