MXPA97003280A - Biocidal combinations sinergisti - Google Patents

Abstract

The present invention is directed to microbiocidal combinations and processes for inhibiting the growth of microorganisms. The combinations and novel processes of the present invention show unexpected activity against microorganisms, including bacteria, fungi and algae. Specifically, the microbiocidal combinations comprise (i) an oxidizing oxidant or biocide such as potassium monopersulfate, sodium perborate, hydrogen peroxide or sodium percarbonate, (ii) a non-oxidizing microbicide such as glutaraldehyde and optionally (iii) a surfactant / dispersant, (iv) an anticorrosive material, and (v) a descaling material

Description

BIOCIDAL SYNERGISTIC COMBINATIONS FIELD OF THE INVENTION The present invention relates to microbiocidal compositions and to the processes of using these microbiocidal compositions to inhibit the growth of microorganisms in aqueous systems. More particularly, the microbiocidal compositions of this invention include a combination of (i) an oxidant, and (ii) a non-oxidizing microbiocide optionally with a surfactant / dispersant, an anti-corrosive material, and / or a descaling material.

BACKGROUND OF THE INVENTION The proliferation of microorganisms and the resulting formation of slime is a problem that commonly occurs in many aqueous systems. The microorganisms that produce the problematic babaza include bacteria, airborne microorganisms, sulfate-reducing bacteria, fungi and algae. Babaza deposits are usually formed in several industrial aqueous systems comprising cooling water systems, systems for pulp and paper mills, oil operations, industrial lubricants, cutting fluids, refrigerants, etc. Babaza formation by microorganisms in these systems is an important and constant problem.

For example, sludge deposits deteriorate cooling towers made of wood and accelerate corrosion when deposited on the metal surfaces of cooling water systems. In addition, sludge deposits tend to clog or clog pipes and valves, and reduce cooling efficiency or thermal exchange on heat exchange surfaces. Pulp and paper mill systems operate under conditions that encourage the growth of microorganisms and often cause obstruction problems. In addition, microorganisms can form large deposits of slime that could dislodge and appear on the paper product as spots, holes or tears. This causes the need to stop the papermaking process to clean the equipment and results in a loss of production time. The babaza can also be objectionable from the point of view of cleaning and sanitation in breweries, wineries, dairies and other hydraulic systems for industrial processing of food and beverages. In addition, sulfate-reducing bacteria are generally problematic in waters used for the secondary recovery of oil or for oil drilling in general. For example, these organisms reduce the sulfates present in the injection water to form deposits of insoluble iron sulfide, and can improve the corrosion of the metals by accelerating the galvanic action. The proliferation of bacteriological contamination in lubricants and cutting fluids is a common problem due to the high temperature and unhygienic conditions found in several metalworking plants. It is often necessary to discard these fluids due to microbiological contamination. Accordingly, because of the aforementioned problems in different industrial processes, numerous biocidal materials have been used to eliminate, inhibit or reduce microbial growth. Several oxidizing biocides have enjoyed wide use in the mentioned applications including chlorine, chlorine dioxide and bromine. However, these oxidizing biocides are not always effective in controlling microbiological growth. For example, oxidizing biocides are consumed by inorganic species such as ferrous iron, reduced manganese, sulfides, etc., as well as by organic compounds commonly found in these systems. In addition, the effectiveness of a biocide is rapidly reduced as a result of exposure to adverse physical conditions such as temperature or contact with incompatible agents in the treatment of water in the system. Therefore, to date, multiple doses or large quantities of expensive biocide chemicals have been required in order to maintain control over microbial growth.

SUMMARY OF THE INVENTION It is an object of the present invention to provide novel microbiocidal compositions that offer improved effectiveness for controlling or inhibiting the growth of microorganisms in an aqueous system. Another objective of this invention is to provide an improved process for controlling microorganisms in aqueous systems, such as pulp and paper mill systems, cooling water systems, metalworking fluids and oil operations. Another objective of this invention is to reduce the level of toxic biocides in industrial water emanations. An advantage of the present invention is that the biocidal compositions allow a reduction in the dosage amount of the biocide required to treat the deleterious microbiota in industrial waters, and significantly reduce the time required to control the microbiological organisms. In accordance with the present invention, certain novel biocidal compositions have been provided which are used to control or inhibit microbial growth, including (i) an effective amount of microbiocide of an oxidant selected from the group of peroxiorganic mono- or di-acids, halogen dioxides, monopersulfates, halogens, halogen releasing compounds, perborates, peroxides, persulfates, permanganates, percarbonates, ozone, and water soluble salts thereof, and mixtures thereof; and (ii) an effective amount of microbiocide of a non-oxidizing microbiocide selected from the group consisting of glutaraldehyde, limonene, bis (trichloromethyl) sulfone, 2- (decylthio) -etanamine, dodecylguanidine hydrochloride, 2- (2-bromo-2- nitroethyl) furan, poly (oxyethylene (dimethyliminium) ethylene (dimethyliminium) ethylene dichloride), alkyldimethyl-benzylammonium chloride, ammonium chloride phosphate of alkylamidopropyl propylene -propylene glycol dimethyl, 2,4,4'-trichloro-2'-ether hydroxydiphenyl, tetra is- (hydroxymethyl) phosphonium sulfate, phosphonium chloride tributyltetradecyl, 2-bromo-2-nitropropane-l, 3-diol, and 2,2-dibromo-2-nitroethanol and blood extract. Also provided according to the present invention is a method for controlling or inhibiting microbial growth in aqueous systems including, by adding to the system (i) an effective amount of microbiocide of an oxidant selected from the group of peroxiorganic mono- or di-acids, dioxides halogen, monopersulfates, halogens, halogen-releasing compounds, perborates, peroxides, persulfates, permanganates, percarbonates, ozone, their water-soluble salts, and mixtures thereof; and (ii) an effective amount of microbiocide of a non-oxidizing microbiocide selected from the group consisting of glutaraldehyde, lignose, bis (trichloromethyl) sulfone, 2- (decylthio) -etanamine, dodecylguanidine hydrochloride, 2- (2-bromo-2) -nitroethyl) furan, poly (oxyethylene (dimethyliminium) ethylene (dimethyliminium) ethylene dichloride), alkyldimethyl-benzylammonium chloride, ammonium chloride phosphate of alkylamidopropyl propylene - propylene glycol dimethyl, 2,4,4'-trichloro-2'-ether of hydroxydiphenyl, tetrakis-hydroxymethylphosphonium sulfate, phosphonium chloride tributyltetradecyl, 2-bromo-2-nitropropane-1, 3-diol, 2,2-dibromo-2-nitroethanol and sanguinaria extract.

DETAILED DESCRIPTION The present invention is directed to certain novel biocide compositions comprising combinations of oxidants and non-oxidizing biocides that are added to an aqueous system in amounts effective to inhibit or control the growth of microorganisms in the aqueous system. More particularly, the biocidal compositions of this invention comprise combinations of (i) an oxidant selected from the group consisting of peroxiorganic mono- or di-acids, halogen dioxides, monopersulfates, halogens, halogen releasing compounds, perborates, peroxides, persulfates , permanganates, percarbonates, ozone, their water-soluble salts, and mixtures thereof and (ii) a non-oxidizing microbiocide selected from the group consisting of glutaraldehyde, limonene, bis (trichloromethyl) sulfone, 2- (decylthio) -etane, dodecylguanidine hydrochloride, 2- (2-bromo-2) -nitroethyl) furan, poly (oxyethylene (dimethyliminium) ethylene (dimethyliminium) ethylene dichloride), alkyldimethyl-benzylammonium chloride, ammonium chloride phosphate of alkylamidopropyl propylene - propylene glycol dimethyl, 2,4,4'-trichloro-2'-ether of hydroxydiphenyl, tetrakis-hydroxymethylphosphonium sulfate, phosphonium tributyltetradecyl chloride, 2-bromo-2-nitropropane-1, 3-diol, 2,2-dibromo-2-nitroethanol, bloodroot extract, and optionally in combination with (iii) a surfactant / dispersant, (iv) an anticorrosive agent and (v) a descaling agent. The above oxidant and non-oxidizing microbiocides of this invention are commercially available or can be synthesized readily from commercially available raw materials by known methods. Suitable peroxides include inorganic peroxides such as hydrogen peroxide, sodium peroxide, as well as organic peroxides such as benzoyl peroxide and the like. Suitable halogen-releasing compounds include the hydantoins such as, for example, 1,3-dichloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin or 1,3-diiodo-5,5-dimethylhydantoin. Suitable peroxiorganic mono- or di-acids include, but are not limited to, peracetic acid, perbenzoic acid, peroxypropionic acid, hexane diperoxoic acid, dodecanediperoxoic acid. Suitable halogen dioxides include chlorine dioxide, bromine dioxide and iodine dioxide. Specific examples of other suitable oxidants include sodium perborate, sodium percarbonate, potassium permanganate, sodium persulfate, potassium persulfate, ammonium persulfate, chlorine, bromine, iodine and compounds that release chlorine, bromine and iodine, sodium monopersulfate. , potassium monopersulfate, and ammonium monocarbonate. Potassium monopersulfate is a preferred oxidant and is commercially available from DuPont as OXONE. The combination of the above oxidant and non-oxidizing biocides provides, without expectations, an improved activity of the biocides that is greater than that of the individual components constituting the mixtures. The microbiocidal compositions of the present invention possess a high degree of activity of the scienicide which could not have been predicted from the known activities of the individual ingredients comprising the combination. The improved activity of the mixture allows a significant reduction in the total amount of the biocide required for the effective treatment of an aqueous system. The improved effectiveness of the biocide of the compositions of the present invention was particularly surprising since not all oxidants offer improved biocide activity when used in combination with non-oxidizing biocides. In fact, some oxidants are actually antagonists when used in combination with non-oxidizing biocides, and result in a lower effectiveness of the biocide than the use of any of the components alone. The biocidal combinations of this invention are effective in controlling and inhibiting the growth and reproduction of microorganisms in cooling water systems, systems for pulp and paper mills, oil operations (for example, applications in oil wells), lubricants and industrial refrigerants. , lagoons, lakes and ponds, etc. The particular type of microorganisms present in these areas varies from one site to another, and even at a given site in a certain period of time. Representative examples of microorganisms that can be effectively treated with the biocidal compositions of the present invention include fungi, bacteria and algae and, more particularly, include genera such as Aspergillus, Penicillium., Candida, Saccharomyces, Aerobacter, Escherichia, Alcaligenes, Bacilli, Chlorella, Spirogy, Oscillatory, Vacuous, Pseudomonas, Salt onela, Staphylococcus, Pullularia, Flavobacteria and Rhizopus.

According to the invention, an aqueous system is treated to inhibit the growth of microorganisms by adding to the aqueous system at least one oxidizing microbiocide and at least one non-oxidizing microbiocide. These components are present in the system at the same time. Although it is possible to combine the oxidant and the non-oxidant biocide, it is usually preferred not to combine the microbiocide with the excess oxidant before being added to the aqueous system because these materials may react adversely when subjected to direct contact each other in their concentrated forms. The dosage amounts of the oxidizing and non-oxidizing biocide that are added to an aqueous system can vary widely depending on the nature of the aqueous system being treated, the level of organisms present in the aqueous system and the level of inhibition desired. An important consideration when dosing the oxidants of the present invention are the levels of ferrous iron, reduced manganese, sulfur, ammonia, organic constituents and the like, with which they can react and therefore consume the oxidants of the present invention. "Oxidant Demand" refers to the difference between the dosage amount of the oxidant and the concentration of the residual oxidant after a prescribed contact time and at a certain pH and temperature. "Oxidant requirement" refers to the dosage amount of the oxidant required to reach a concentration of the residual oxidant determined at a prescribed contact time, pH and temperature. Since the levels of ferrous iron, reduced manganese, sulfur, etc. can vary widely from one system to another, the oxidant demand should be determined for the aqueous system that is being treated according to the method of this invention. For purposes of this invention, the dosage amount of the oxidant that is added to an aqueous system, ie, an effective amount at the biocide level, refers to the concentration of the residual oxidant in an aqueous system. The concentration of residual oxidant can be easily determined by a person skilled in the art through conventional means. In general, the dosage amount of the oxidant can be from 0.1 ppm to 100 ppm, preferably from about 0.5 ppm to about 45 ppm. The dosage amount of the microbiocide in the system can be from 0.1 ppm to 125 ppm, preferably from approximately 0.5 ppm to approximately 45 ppm. When microbiocides and oxidants are present in the above amounts, the resulting combination possesses a higher degree of effectiveness against microorganisms than the individual components comprising the combination. Although larger amounts of the microbiocides or the oxidant can be used without harmful effect, these larger amounts increase the cost of the treatment and generally provide little additional benefit. The biocidal compositions of the present invention can optionally be used in combination with one or more surfactants / dispersants to disperse the biomass and to improve the dispersibility and stability of these microbiocidal formulations. Suitable surfactants / dispersants include, but are not limited to, cationic, nonionic, anionic or amphoteric surfactants, and polymers such as fluorinated surfactants, polyaryl alkylaryl alcohols, polyether alcohols, sodium dodecylsulfate, sodium nonylbenzene sulfonate, sodium dioctylsulfosuccinate, octylphenoxypolyethoxyethanol, condensates of ethylene oxide and / or propylene with long-chain alcohols, mercaptans, amines, carboxylic acids, naphthalene-formaldehyde condensed sodium sulfonate and lignin sulphonate, alkylbenzene sulfonates and sulfates, sodium linear dodecylbenzene sulfonate, block copolymers of propylene oxide - ethylene oxide as for example, a polyoxypropylene glycol polymer with a molecular weight of 1500-2000 which has been reacted with from 5-30% by weight of ethylene oxide (commercially available in BASF as the Pluronic and Tetronic surfactants), and the like. Preferred fluorinated surfactants include those manufactured by 3M such as FC-99, FC-100 and FC-129. FC-99 is an anionic surfactant that is a 25% active solution of amine-perfluoroalkyl sulfonates in water. FC-100 is an amphoteric surfactant that is an active solution to 28% of fluorosurfactant solids in glycol / water. FC-129 is an anionic surfactant that is a 50% solution of fluorinated alkyl carboxylates of potassium in water, butyl Cellosolve and ethanol. The dosage amount of the surfactant / dispersant in the aqueous system is not important, per se, as long as of course it is added in an affective amount to disperse the biomass or stabilize a particular microbiocidal formulation. These dosage amounts are generally from 0.5 to 500 ppm. The biocidal compositions of the present invention can also be used in combination with an anticorrosive material. Suitable anticorrosive materials include, but are not limited to, phosphates such as sodium tripolyphosphate or tetrapotassium pyrophosphate, phosphonates, carboxylates, etc. These components can be added to help protect mild steel from corrosive attack by the oxidant. The anti-corrosive material can be mixed with the oxidant before being added to the system or can be added separately. The anticorrosive material is usually added to the system in a dosage amount of from 0.5 to 50% based on the total amount of oxidizing and anticorrosive material in the mixture. More preferably, the amount of anticorrosive material is at least 1% of the total amount of oxidizing and anticorrosive material in the mixture. The biocidal compositions of this invention can also be used in combination with other biocides that further improve the synergistic effectiveness. For example, combinations of preferred biocides include glutaraldehyde with isothiazolone. The ratio of these biocidal combinations can vary from 1:10 to 10: 1 on a basis by weight. A preferred isothiazolone is a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. The biocidal compositions of the present invention may also be used in combination with a descaling material. Suitable de-scaling materials include, but are not limited to, polyacrylates such as sodium polyacrylate, phosphonates such as hydroxyethylidene diphosphonic acid, etc. The descaling material is usually added to the system in a dosage amount of from 0.5 to 50% based on the total amount of oxidizing and descaling material in the mixture. The oxidants of this invention may be in solid or liquid form and may be diluted with a solid or liquid carrier. Powders can be prepared with finely divided solid carriers including talc, clay, pyrophyllite, diatomaceous earth, hydrated silica, calcium silicate, or magnesia carbonate. The powders may generally contain from 1 to 15 percent of the microbiocides of this invention, while a wetted powder can be obtained by increasing the ratio of the microbiocide to about 50 percent or more. A typical formulation of a moistened powder comprises from 20 percent to 50 percent of the appropriate compounds of this invention, from 45 percent to 75 percent of one or more finely divided solids, from one percent to five percent of a humidifying agent, and from one percent to five percent of a dispersing agent. The oxidants of this invention can also be used in the form of liquid concentrates. These are prepared by diluting or dissolving the oxidants and / or microbiocides of this invention in a solvent together with one or more surfactants. The following examples are provided to illustrate the present invention in accordance with the principles of this invention, but should not be construed as limiting the invention in any way, except as indicated in the appended claims. All parts and percentages are by weight unless otherwise indicated. The synergism of the two-component microbiocidal combinations of the present invention was demonstrated by testing a wide range of concentrations and ratios of compounds, generated by double serial dilutions in a liquid. The liquid medium is composed of deionized water supplemented with inorganic constituents to simulate industrial water. The work was carried out with the bacteria Enterobacter aerogenes or a culture of mixed bacteria formed by Enterobacter aerogenes, Escherichia coli, Pseudomons aeruginosa, and Bacillus subtilis; the fungus Aspergillus niger; and for the algae, Chlorella vulgaris, or Scenedesmus quadracauda. All the organisms were representative of those found generally in industrial ws. The contact periods varied from 2-24 hours and incubations of subcultures on the surfaces of the agar were carried out at temperatures, times and lighting conditions that allowed the growth of visible colonies. For the bacteria, the agar was Soya Triptica, for the algae CHU-10, and for the fungi, the Yeast Extract of Potato Dextrose. Uniform inoculations within simul industrial w tests were performed in such a way that all test solutions and all exposures of organisms were carried out with the same density of organisms per ml. After the inoculation of simul industrial ws, these cell densities were thousands per ml for fungi-spores and algae, and millions per ml for bacteria. After contact of the bacterium-biocide in the liquid medium and from the subculture to the agar, the organic nutrients in the form of Tryptic Soybean Broth were added to each tube or vessel of the bioassay, followed by the re-incubation to determine the viability of any surviving organism expressed as turbidity (growth). The lack of growth of the bacteria resulted in a clear medium without turbidity. Several endpoints of colony formation were used to calculsynergies from a reduction of 90 percent to 100 percent compared to untre controls. The results of the test for the demonstration of the synergism of the biocidal combinations are illustr in the following examples. Each table in the examples is organized to show the synergy by illustrating (1) the concentration of each test mial acting alone, required to produce a given endpoint in the prevention of growth or inhibition of the colony forming unit, as compared to untre controls; and (2) the lowest concentrations required of the combined test mials.

Example 1 This example shows the synergies between glutaraldehyde and H202 using the bacterium Enterobacter aerogenes and a culture of mixed bacteria. Table 1 Concentrations of Active Biocide to Achieve a 100% Inhibition of Enterobacter aerogenes, 4 Hours of Glutaraldehyde Contact. Ms / 1 H202. Ms / 1 64 0 0 200 4 6.3 Table 2 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Hours of Glutaraldehyde Contact. Ms / 1 H202. Ms / 1 100 0 0 100 3.8 50 7.5 25 15 3.1 Example 2 This example demonstrates the synergies between glutaraldehyde and H202 using the green algae Chlorella vulgaris and Scenedesmus quadracauda. Table 3 Concentrations of Active Biocide to Achieve a 100% Inhibition of Chlorella vulgaris plus an Unknown Auxiliary Bacteria, 23 Hours of Contact Glutaraldehyde. Ms / 1 H202. Ms / 1 > 320 0 0 40 5 20 Table 4 Active Biocide Concentrations to Achieve 100% Inhibition of Scenedesmus quadracauda, 4 Hours of Glutaraldehyde Contact. M / 1 H202. M / 1 80 0 0 40 5 5 Example 3 The data (Table 5) indicate hydrogen peroxide as a synergist with a combination of glutaraldehyde and Kathon 886F (4: 1 active) using the green algae Chlorella vulgaris.

Kathon 886F is a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. Table 5 Concentrations of Active Biocide to Achieve a 100% Inhibition of Chlorella vulgaris 2 Hours of Contact Glutaraldehyde, Kathon. M / 1 H202, Mcr / 1 416 0 0 100 104 6.3 52 12.5 Example 4 This example demonstrates the synergies between limonene and oxidizing biocides using a mixture of four species of bacteria. Table 6 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Hours of Contact d-Limonene, Mq / 1 H; > 2 . Ms / 1 Peracetic Acid, Ms / 1 > 2,000 0 0 0 300 0 0 0 23.5 31 75 0 31 0 11.8 Example 5 This example demonstrates the synergies between 2- (decylthio) -etanamine (DTEA) and the hydrogen peroxide of the oxidizing biocide using a culture of mixed bacteria (Table 7). Table 7 Active Biocide Concentrations to Achieve 100% Inhibition of Four Species of Bacteria, 4 Hours of Contact DTEA. Mcr / 1 H202. Ms / 1 100 0 0 100 25 3.1 EXAMPLE 6 This example demonstrates the synergies between 2,2-dibromo-2-nitroethanol and the hydrogen peroxide of the oxidizing biocide. Table 8 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Species of Bacteria Mexicated, 4 Hours of Contact 2, 2-Dibromo-2-nitroethanol. Mcr / 1 H202, Mq / 1 7.8 0 0 > 200 3.9 3.1 Example 7 This example demonstrates the synergies between poly (oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride) (WSCP) and the hydrogen peroxide of the oxidizing biocide. In this test, the bacterium Enterobacter aerogenes was used as the test organism.

Table 9 Active Biocide Concentrations to Achieve a 100% Inhibition of Enterobacter aerogenes, 4 Hours of Contact WSCP. M / 1 H202. Ms / 1 2 0 0 30 1 5 Example 8 This example demonstrates the synergies between the tetradecyldimethylbenzylammonium chloride and the hydrogen peroxide of the oxidizing biocide. Table 10 Concentrations of Active Biocide to Achieve 100% Inhibition of Enterobacter aerogenes, 4 Hours of Contact tetradecyldimethylbenzylammonium Chloride, Mq / 1 H202, Mg / 1 20 0 0 100 2.5 20 5 10 Example 9 This example demonstrates the synergy between tetrakis-hydroxymethylphosphonium sulfate and hydrogen peroxide (Table 11). Table 11 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Contact Hours tetrakis-hydroxymethylphosphonium sulfate, Mg / 1 H 02. Mq / 1 31.2 0 0 100 15.6 50 EXAMPLE 10 This example demonstrates the synergy between the phosphonium chloride tributyltetradecyl and the hydrogen peroxide (Table 12). Table 12 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Species of Bacteria Mixed, 4 Hours Contact Phosphonium tributyltetradecyl chloride. Mq / 1 H20. Mq / 1 31.3 0 0 200 7.8 3.1 Example 11 This example demonstrates the synergies between 2-bromo-2-nitropropane-1,3-diol and hydrogen peroxide (Table 13). Table 13 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Contact Hours 2-bromo-2-nitropropane-l. 3-diol. Mq / 1 H202. Mq / 1 62.5 0 0 100 7.8 25 15.6 6.3 Example 12 This example demonstrates the synergies between ammonium chloride phosphate cocamidopropyl propylene glycol dimethyl and hydrogen peroxide (Table 14). Table 14 Concentrations of Active Biocide to Achieve a 100% Inhibition of Enterobacter aerogenes, 2 Hours of Contact Ammonium chloride phosphate cocamidopropyl propylene licol dimethyl. Mq / 1 H202, Mq / 1 78 0 0 200 39 2.5 Example 13 This example demonstrates the synergies between 2, 4,4'-trichloro-2'-hydroxydiphenyl ether and hydrogen peroxide (Table 15). Table 15 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Contact Hours 2, 4.4 '-trichloro-2' -hydroxydiphenyl ether. Mq / 1 H202. Mq / 1 500 0 0 150 31.2 75 Example 14 The data (Table 16) show the hydrogen peroxide as a synergist with the sanguinaria extract against a culture of mixed bacteria. Table 16 Active Biocide Concentrations to Achieve 100% Inhibition of Four Mixed Bacteria Species, 4 Hours of Contact Bloodroot Extract, Mq / 1 H20, Mq / 1 31.2 0 0 200 3.9 25 7.8 3.1 Example 15 This example demonstrates the synergies between poly (oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride) (WSCP) and potassium monopersulfate. Table 17 Active Biocide Concentrations to Achieve 99.93% Inhibition of Four Mixed Bacteria Species, 15 Hours of WSCP Contact, Mg / 1 Potassium Monopersulfate, Mq / 1 16 0 0 > 4 8 0.5 Example 16 This example demonstrates the synergies between glutaraldehyde and sodium hypochlorite. Table 18 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Hours of Contact Glutaraldehyde, Mq / 1 Sodium Hypochlorite, Mq / 1 as Cl2 25 0 0 > 1 12.5 0.016 Example 17 This example demonstrates the synergies between glutaraldehyde and bromine. Table 19 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 2 Hours of Glutaraldehyde Contact, Mq / 1 Bromine, Mg / 1 50 0 0 1 3.1 0.125 Example 18 Experimental results (Table 20) indicate peracetic acid as a synergist with glutaraldehyde using a culture of mixed bacteria. Table 20 Active Biocide Concentrations to Achieve a 100% Inhibition of Four Mixed Bacteria Species, 4 Hours of Glutaraldehyde Contact, Mq / 1 Peracetic Acid. Mq / 1 50 0 0 25 6.3 6.3 Example 19 Additional combinations showing synergistic microbiocidal activity are the following: (I) Bis (trichloromethyl) sulfone and potassium percarbonate. (2) Dodecylguanidine hydrochloride and sodium perborate. (3) 2- (2-Bromo-2-nitroethyl) furan and ozone. (4) Glutaraldehyde and potassium permanganate. (5) Glutaraldehyde and chlorine dioxide. (6) Phosphonium tributyltetradecyl chloride and sodium persulfate. (7) B i s (tr ic lor omet i 1) sulfone and diperoxydodecanoic acid. (8) d-Limonene, hydrogen peroxide and peracetic acid. (9) Glutaraldehyde, hydrogen peroxide and sodium nonylbenzene sulfonate. (10) Glutaraldehyde, peracetic acid and a polyoxypropylene glycol polymer with a molecular weight of 1,650 which has been subjected to reaction with 25% by weight of ethylene oxide (commercially available from BASF as Pluronic L62). (II) d-Limonene, hydrogen peroxide and sodium dioctyl sulfosuccinate.

Example 20 In this experiment, 4,5-dichloro-l, 2-dithiol-3-one (Dithiol) was evaluated under the experimental conditions and it was found that there was no synergy in the inhibition between Dithiol and hydrogen peroxide. The results (Table 21) showed no synergy, but a very strong antagonism between the two test materials, indicating that not all microbiocides can be combined with an oxidant to control the growth and deposition of water-forming microorganisms. Table 21 Survival of the Colony Forming Unit in a Tryptic Soybean After 4 Hours of Exposure to Combinations of H202 and Ditiol Four Species of Mixed Bacteria NS Survival of the Unit Colony Forming Treatment Ditiol 15.6 ppm 0 Ditiol 15.6 ppm + > 2 x 10c H202 25 ppm Ditiol 62.5 ppm + > 2 x 10 'H202 25 ppm Ditiol 62.5 ppm + > 2 x 10c

Claims (11)

1. A microbicidal composition for inhibiting and controlling the growth and deposition of slime-forming microorganisms in aqueous systems comprising: (i) an microbiocidally effective amount of an oxidant to inhibit the growth of microorganisms, selected from the group consisting of mono - and peroxiorganic acids, halogen dioxides, monopersulfates, halogens, halogen-releasing compounds, perborates, peroxides, percarbonates, perganic acid, chlorine dioxide, persulfates, diperoxydodecanoic acid, permanganates, ozone, and mixtures thereof; and (ii) an microbiocidally effective amount of a microbiocide to inhibit the growth of microorganisms, selected from the group consisting of glutaraldehyde, limonene, bis (trichloromethyl) sulfone, 2- (decylthio) -etanamine, dodecylguanidine hydrochloride, 2- ( 2-bromo-2-nitroethyl) furan, poly (oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride, alkyldimethyl-benzylammonium chloride, ammonium chloride phosphate of alkylamidopropyl propylene-propylene glycol dimethyl, 2,4,4'-trichloro- 2 '-hydroxydiphenyl ether, tetrakis- (hydroxymethyl) phosphonium sulfate, tributyltetradecyl phosphonium chloride, 2-bromo-2-nitropropane-1, 3-diol, 2,2-dibromo-2-nitroethanol, sanguinary extract and mixture thereof .

2. - The composition of clause 1 wherein (i) is selected from monopersulfates, halogens, halogen releasing compounds, perborates, peroxides, percarbonates, perganic acid, chlorine dioxide, persulphates, diperoxydodecanoic acid, permanganates, ozone and mixtures thereof .

3. - The composition of clause 1 characterized by also comprises a surfactant and / or a dispersant.

4. - The composition of clause 1 characterized in that it comprises 0.5 ppm to 45 ppm of (i) and 0.5 ppm to 45 ppm of (ii).

5. A method for inhibiting and controlling the growth and deposition of slime-forming microorganisms in aqueous systems, which includes adding to the aqueous system a microbicidal composition comprising: (i) an microbiocidally effective amount of an oxidant to inhibit the growth of microorganisms, selected from the group consisting of peroxiorganic mono- and di-acids, halogen dioxides, monopersulfates, halogens, halogen-releasing compounds, perborates, peroxides, percarbonates, perganic acid, chlorine dioxide, persulfates, diperoxydodecanoic acid, permanganates, ozone , and mixtures thereof; and (ii) an microbiocidally effective amount of a microbiocide to inhibit the growth of microorganisms, selected from the group consisting of glutaraldehyde, limonene, bis (trichloromethyl) sulfone, 2- (decylthio) -etanamine, dodecylguanidine hydrochloride, 2- ( 2-bromo-2-nitroethyl) furan, poly (oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride, alkyldimethyl-benzylammonium chloride, ammonium chloride phosphate of allylamidopropyl propylene-propylene glycol dimethyl, 2,4,4 • -trichloro- 2 '-hydroxydiphenyl ether, tetrakis- (hydroxymethyl) phosphonium sulfate, tributyltetradecyl phosphonium chloride, 2-bromo-2-nitropropane-1, 3-diol, 2,2-dibromo-2-nitroethanol, sanguinary extract and mix of them.

6. - A method according to clause 5 where the aqueous system is a hydraulic system of a paper and pulp mill.

7. - A method according to clause 5 in which the microorganisms are sulfate-reducing bacteria and in which the aqueous system is an oil operation system.

8. - A method according to clause 5 in which the microorganisms include algae, bacteria and fungi.

9. - A method according to clause 5 wherein the aqueous system is a cooling water system.

10. - A method according to clause 5 wherein (i) is selected from monopersulfates, perborates, peroxides and percarbonates and (ii) is selected from the group consisting of glutaraldehyde and the mixture of glutaraldehyde, 5-chloro-2-methyl-4 -isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.

11. - A method according to clause 5, comprising a ratio of at least 10 parts of the microbiocide and 90 parts by weight of the oxidant with 90 parts by weight of the microbiocide and 10 parts by weight of the oxidant.