阅读说明：本技术 在生物膜控制中表现出协同作用的组合物 (Compositions exhibiting synergistic effects in biofilm control ) 是由 J·S·查普曼 C·E·科恩萨洛 于 2018-10-12 设计创作，主要内容包括：公开了一种控制和去除与水性工业系统接触的表面上的生物膜的方法,其包括以下步骤：加入有效量的生物膜破坏剂,并且向被处理的水性系统中加入杀生物剂,以从与所述水性系统接触的表面上减少和去除形成生物膜的微生物。还公开了聚乙烯亚胺和氧化性杀生物剂的协同组合物。(Disclosed is a method for controlling and removing biofilm on surfaces in contact with aqueous industrial systems comprising the steps of: adding an effective amount of a biofilm disruptor, and adding a biocide to the treated aqueous system to reduce and remove biofilm-forming microorganisms from surfaces in contact with the aqueous system. Also disclosed are synergistic compositions of polyethyleneimine and an oxidizing biocide.)

1. A method of controlling and removing biofilm on a surface in contact with an aqueous system, the method comprising the steps of: adding a biofilm disruptor and a biocide to the aqueous system.

2. The method of claim 1, wherein the biocide is an oxidizing biocide.

3. The method of claim 2, wherein the oxidizing biocide is selected from the group consisting of dibromocyanopropionamide, halogenated hydantoins such as bromochlorodimethyl hydantoin, hypobromous acid, trichloroisocyanuric acid, haloamine-based biocides, dihaloamine-based biocides, and combinations thereof.

4. The method of claim 1, wherein the biocide is selected from the group consisting of haloamine-based biocides and dihaloamine-based biocides.

5. The method of any one of claims 1 to 4, wherein the biocide comprises at least one of monochloramine or dichloramine.

6. The method of claim 1, wherein the biocide is derived from the reaction of a chlorine moiety with a nitrogenous compound capable of providing an ammonium ion.

7. The method of claim 6, wherein the biocide is derived from the reaction of chlorine moieties with ammonium hydroxide, ammonium chloride, ammonium sulfate, ammonium acetate, ammonium bicarbonate, ammonium bromide, ammonium carbonate, ammonium carbamate, ammonium sulfamate, ammonium nitrate, ammonium oxalate, ammonium persulfate, ammonium phosphate, ammonium sulfide, urea, and urea derivatives and combinations thereof.

8. The method of claim 6 or 7, wherein the chlorine moiety is hypochlorite.

9. The method of any one of claims 1 to 8, wherein the biocide comprises a blend of ammonium-derived chloramine compounds.

10. The method of claim 1, wherein the biocide is a non-oxidizing biocide.

11. The method of claim 10, wherein the non-oxidizing biocide is selected from the group consisting of isothiazolone biocides, glutaraldehyde, formaldehyde and formaldehyde-releasing compounds, hydantoins, tetrahydroxyphosphonium chlorides, and combinations thereof.

12. The method of any one of claims 1 to 11, wherein the biofilm disruption agent comprises polyethyleneimine ("PEI").

13. The method of claim 12, wherein the weight average molecular weight of the PEI is from about 500 daltons to about 750,000 daltons, preferably from about 500 daltons to 100,000 daltons, more preferably from about 1000 daltons to about 3000 daltons.

14. The method of claim 12 or 13, wherein the PEI has a charge density of about 8 to about 20meq/g of material, preferably about 10 to about 20meq/g of material, most preferably about 16 to 20meq/g of material.

15. The method of any one of claims 1 to 14, wherein the concentration of biofilm disruptor is from about 1 milligram per liter (mg/L) to about 200mg/L of aqueous system treated, or from about 1mg/L to about 100mg/L of aqueous system treated, or from about 1mg/L to about 50mg/L of aqueous system treated, preferably from about 1mg/L to about 15mg/L of aqueous system treated, more preferably from about 1mg/L to about 10mg/L of aqueous system treated.

16. The method according to any one of claims 1 to 15, wherein the biocide is dosed in the following amounts: in milligrams of biocide per liter of water treated as Cl₂About 1.0mg/L to about 15mg/L, more preferably Cl based on milligrams of biocide per liter of water being treated₂It is about 1mg/L to about 10 mg/L.

17. The method of any one of claims 1 to 16, wherein the weight ratio of biocide to biofilm disruptor is from about 1:1 to about 1:80 or from about 1:1 to about 1:32, preferably from about 1:1 to about 1:20, more preferably from about 1:1 to about 1:8 by weight.

18. The method of any one of claims 1 to 17, wherein the biofilm disruption agent is added in an amount of from about 1mg/L to about 100mg/L, preferably from about 1mg/L to about 50mg/L or more preferably from about 1mg/L to about 15mg/L, based on the volume of water being treated, and wherein the biofilm disruption agent comprises polyethyleneimine.

19. The method according to claim 18, wherein the amount of biofilm disrupter is from about 1mg/L to about 10mg/L, the dosage of biocide is from about 1mg/L to about 10mg/L as active chlorine, and the weight ratio of biocide to biofilm disrupter is from about 1:1 to about 1:8, and wherein the biofilm disrupter comprises polyethyleneimine.

20. The method of any one of claims 1 to 19, wherein the aqueous system is selected from the group consisting of cooling towers, evaporators, coolers, condensers, pulp and paper mills, boilers, wastewater, regeneration wastewater, pulp slurry, starch slurry, clay slurry, biorefinery water, sludge, colloidal suspensions, irrigation water, oil and gas water, and combinations thereof.

21. A composition comprising a biofilm disrupter and a biocide, wherein the biofilm disrupter is a polyethyleneimine and the biocide is a haloamine.

22. The composition of claim 21, wherein the haloamine is selected from the group consisting of chloramine, dichloramine, and combinations thereof.

23. The composition of claim 21 or 22, wherein the weight ratio of biofilm disrupter to oxidizing biocide is about 1 part biocide: greater than 1 part of biofilm disrupter.

24. The composition according to any one of claims 21 to 23, wherein the weight ratio of biocide to biofilm disruptor is from about 1:1 to about 1:80, or from about 1:1 to about 1:40, or from about 1:1 to about 1:32, preferably from about 1:1 to about 1:20, more preferably from about 1:1 to about 1: 8.

Technical Field

The present disclosure relates to the control of microorganisms in aqueous environments.

Background

Microbial biofilms in industrial, commercial and residential systems and structures have a significant negative impact on the function and operation of these systems and structures, including reducing heat transfer, plugging pipes and lines, acting as reservoirs for pathogens, causing mechanical and structural failures, promoting corrosion, contaminating and degrading products, drinking and recreational water, and reducing aesthetic value.

In the present context, biofilm is defined as microorganisms that settle, attach and then grow or live on a surface. These microorganisms may consist of a single species or be multispecific and may consist of bacteria, viruses, fungi, algae, and micro-or macro-eukaryotes such as amoebae, diatoms, nematodes, and worms. Biofilms may be submerged in liquids, splash zones, wet environments, and even dry environments, such as those found on surfaces of statues and buildings. Biofilms are structurally composed of microbial cells encapsulated in a molecularly diverse polymer matrix composed of polysaccharides, proteins, DNA and many small molecules. In their natural environment, they can also entrain dirt, soil, plant matter, and other environmental components. This material is commonly referred to as mucus. The anatomy of a biofilm is widely influenced by the environmental composition and shear forces provided by the movement of the substrate over the membrane.

In contrast to free floating in bulk fluids, the results of microorganisms living in a fixed environment are manifested in the large differences in their expression of the genome, from a few genes to almost 50% of the genome. These changes have a dramatic effect on the sensitivity of biofilm cells to chemical biocides, antibiotics, and other environmental stressors. In addition to a wide range of physiological changes, biofilm cells are also present in the polymer matrix, which may interfere with the entry of biocides or antibiotics into the cells, thereby further reducing their sensitivity. Biocide and antibiotic sensitivities have been documented to vary by more than a thousand fold.

The most common method of controlling biofilms is the application of chemical biocides, including oxidizing biocides, reactive biocides, and membrane active biocides. Regardless of the type of mechanism of the biocide, for the reasons discussed in the preceding paragraph, it has been demonstrated that biofilms are much more resistant to the inhibitory and killing effects of biocides, resulting in the need to apply high concentrations of biocides to achieve the desired effect.

Oxidizing biocides are commonly used as biofilm control agents in various industrial, commercial and civilian applications because they are inexpensive and effective against planktonic microorganisms. They can be effective in controlling microorganisms, but high application rates, treatment costs, corrosive effects of oxidizing agents on building materials, and regulatory limitations in some cases often make it difficult to effectively apply them for long-term biofilm control.

Oxidizing biocides, while capable of killing most biofilm populations, are not effective in removing biofilm from surfaces. This is unsatisfactory because some of the negative effects of biofilms result from their physical presence on surfaces. For example, biofilm is a good insulator and greatly impedes heat transfer in cooling towers and coolers, and although treated biofilm may essentially die, it still insulates the surface. In addition, the large number of dead cells provides a ready source of nutrients for the viable fragments of the treated population, and the biofilm tends to rapidly re-grow to its original density.

An auxiliary treatment in the form of a biofilm disruption material is carried out in conjunction with a biocide to enhance the efficacy of killing and removing microorganisms from the surface. These biofilm disrupters are most commonly anionic, cationic or nonionic surfactants, whose postulated mechanism is interaction with the biofilm structure, which both allows biocides to more effectively penetrate the biofilm and remove it by their surface active nature. Despite the long-standing presence of these biofilm disruptors in the market, these biofilm disruptors are often likely to be underutilized due to the efficacy of treatment procedures using both oxidizing and non-oxidizing biocides. However, market, cost and environmental issues have led to a desire to reduce the use of biocides without reducing the efficacy of microbiological control procedures, and there is an increasing interest in dispersants in many markets, particularly industrial cooling waters. As expected, the relative abilities of these biofilm disruptors range from poor to good, and their efficacy may be influenced by the composition of the bulk matrix (bulk matrix). It is also expected that some combinations of oxidizing biocides and biofilm disrupters will be more effective than others based on their chemical interaction and effect on biofilm structure.

Detailed Description

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

It has surprisingly been found that some combinations of biocides, preferably oxidizing biocides, and biofilm disrupters exhibit synergistic control of biofilm both in killing the microorganisms and in removing them from the surface. The combined effect of the biocide and the biofilm disrupter is much greater than the mere additive effect of the two chemicals, so that the amount of one or both chemicals can be greatly reduced and the desired endpoint of biofilm control is still achieved. This synergistic interaction is not found in all combinations of chemicals nor in all ratios of the two chemicals.

Disclosed is a method for controlling and removing biofilm on surfaces in contact with aqueous industrial systems comprising the steps of: an effective amount of a biofilm disrupter is added, and a biocide is added to the treated aqueous system to reduce and remove biofilm-forming microorganisms from surfaces in contact with the aqueous system.

The invention also provides a synergistic composition comprising a biofilm disruptor and a biocide.

Oxidizing biocides useful in the present invention include: sodium hypochlorite, calcium hypochlorite and other hypochlorites, hypochlorous acid, hypobromous acid, monohaloamine biocides derived from ammonium hydroxide, ammonium chloride, ammonium sulfate, ammonium acetate, ammonium bicarbonate, ammonium bromide, ammonium carbonate, ammonium carbamate, ammonium sulfamate, ammonium nitrate, ammonium oxalate, ammonium persulfate, ammonium phosphate, ammonium sulfide, urea and urea derivatives, and other nitrogen-containing compounds capable of providing ammonium ions and reacting with a chlorine or bromine moiety, such as a chlorinated or brominated oxidant, preferably hypochlorous acid or hypochlorite, preferably hypochlorite; and blends of ammonium-derived chloramine compounds, such as monochloramine and dichloramine. Such haloamine biocides are well known in the art, see for example US 7285224, US7052614, US 7837883, US 7820060. Other oxidizing biocides include dibromocyanopropionamide, bromochlorodimethylhydantoin and other halogenated hydantoins, and trichloroisocyanuric acid. Non-oxidizing biocides used against biofilms and intended to work with dispersants include isothiazolone biocides, glutaraldehyde, formaldehyde and formaldehyde-releasing compounds, tetrahydroxyphosphonium chloride, and other non-cationic biocides.

The present invention provides a method of controlling microbial biofilm on surfaces in contact with systems, including but not limited to aqueous systems, comprising adding to the system a synergistic combination of an oxidizing biocide and a biofilm disruptor or dispersant comprising a polyethyleneimine surfactant. Polyethyleneimine is a high molecular amine with a high charge density that allows it to be tightly adsorbed on negatively charged substrates.

The charge density may be from 8 to 20meq/g of material, preferably from 10 to 20meq/g of material, most preferably from 14 to 20meq/g of material. It is a water-soluble polymer, usually formed by the polymerization of ethyleneimine. It may contain primary, secondary and tertiary amines. Exemplary polyethyleneimines may be under the trade name Lupasol^TM(BASF, Florham Park, NJ).

The biofilm disrupter used in the present invention is polyethyleneimine ("PEI"), a low molecular weight ethyleneimine copolymer. The polyethyleneimine has an average molecular weight of less than 750,000 daltons, preferably less than 100,000 daltons and greater than 500 daltons. The average molecular weight is generally 750 to 25,000, preferably 800 to 4000, more preferably about 1000 to about 3000. Examples of polyethyleneimine surfactants include, but are not limited to, BASF Lupasols (BASF Corporation, Florham Park, n.j.). The dispersant includes from about 20 to about 98 weight percent polyethyleneimine, with the remainder of the dispersant including water, which may be present in an amount of from about 2 to about 80 weight percent. Other components may include solvents, such as low molecular weight alcohols, such as ethanol, methanol, and butanol.

One embodiment of the polyethyleneimine is comprised of about 40% to about 50% water and about 40% to about 50% PEI polymer with aziridine. The concentrations provided in the present invention are for the polyethyleneimine polymer only and other components or solvents in commercially available PEI products are not considered part of the dosage range. For example, a 50 gram 50% PEI product is a dosage of 25 grams PEI.

The present invention also provides a synergistic composition comprising a biofilm disrupter and a biocide, wherein the biofilm disrupter is polyethyleneimine and the biocide is a haloamine preferably selected from monohaloamines, dihaloamines and combinations thereof. The haloamine may be chloramine. Preferably, the weight ratio of biofilm disruptor to oxidizing biocide is 1 part biocide: less than 1 part of biofilm disruptor. The weight ratio of biocide to biofilm disruptor may be 1:1 to 1:80, or 1:1 to 1:40, or 1:1 to 1:20, more preferably about 1:1 to about 1: 8.

The interaction of two chemicals in a composition can occur in three possible ways. In the first mode, the two chemicals interact in a negative way to reduce the combined effect of the composition, so that the result obtained is less than that expected from their combined activities. Thus, if the measured variable of one agent itself reaches a value of 50 and the second agent itself reaches a value of 50, the combined decrease in both will be less than 100 under negative interaction. Another way in which one may interact is superposition, the end result being a simple addition of the two values. Thus, if two agents, each capable of reaching a value of 50, are combined, their total combined value will be 100. In a third way, which is optimal in the case of microbial control, the result of combining two agents each capable of reaching a value of 50 would be a certain value greater than 100.

Researchers have developed formulas for measuring the nature and extent of interaction between components in a composition. In the field of microbial control, the most commonly used equation is described in Kull et al (Kull et al, 1961, J.appl.Microbiology9:538), which is incorporated herein by reference. Recent examples of the use of this equation in patents are US #9555018 "synergistic combination of organic acids useful for controlling microorganisms in industrial processes" and US #8778646 "methods of treating microorganisms during propagation, regulation and fermentation using hops acid extracts and organic acids". The original Kull equation used the Minimum Inhibitory Concentration (MIC) of the antimicrobial as the endpoint of the assay. The MIC value is the lowest measured concentration of antimicrobial that produces an inhibitory effect on the microbial culture. Inhibition can be determined visually by measuring the turbidity of the microbial culture; in other possible ways, it can also be determined by counting living cells by culture-based methods or microscopy or by some measure of metabolic activity. The equation is shown below:

synergy index ═ end point (end point a/end point a) + (end point B/end point B), where end point a is the end point of reagent a itself, end point a is the end point of reagent a in combination with reagent B, end point B is the end point of reagent B itself, and end point B is the end point of reagent B in combination with reagent a.

In this work, the efficacy of these agents, alone or in combination, was determined by measuring the number of viable cells in the model biofilm remaining after treatment. The minimum biofilm clearance value (MBEC) was defined as a 95% reduction in the number of viable cells compared to untreated controls. Relatively non-toxic dispersants cannot achieve this kill level at physically possible concentrations, so MBEC is considered the highest value tested for these agents. Because this value is used as a divisor in the synergy index equation, the highest test value is actually an underestimated value of MBEC, and thus the synergy index value is also underestimated.

The invention is primarily intended for industrial process waters, in particular cooling towers, evaporators, coolers and condensers, but also for any industrial process where biofilm formation in an aqueous matrix is detrimental to the process. It is contemplated that the present invention may also be used in geothermal fluid treatment, oil and gas recovery, and processes using clean-in-place systems.

The concentration of the biofilm disrupter, preferably PEI, to be used is in the range of 1 to 200 milligrams per liter (ppm) of water, or preferably 1 to 100 milligrams per liter (ppm) of water, or 1 to 50mg/L, 1 to 15mg/L, more preferably 1 to 10mg/L in the aqueous system being treated.

In milligrams of biocide per liter of water treated, as Cl₂The biocides on an active basis were dosed in the following amounts: usually as Cl₂At least 1.0(mg/L) ppm based on Cl₂At least 1.5ppm, or preferably Cl₂At least 2ppm or more in terms of Cl₂At least 2.5ppm or more in terms of Cl₂Up to 15ppm or more preferably as Cl₂Up to 10 ppm. Preferably, the dosage of biocide is 1.5mg to 10mg biocide per liter of water being treated.

Preferably, the weight ratio of biofilm disruptor to biocide, preferably oxidizing biocide, is 1 part biocide: at least 1 part of a biofilm disruptor. The weight ratio of biocide to biofilm disruptor may be 1:1 to 1:80 or 1:1 to 1:40, preferably 1:1 to 1:20, more preferably 1:1 to 1: 8. Each component is measured by weight.

The person skilled in the art will be able to determine the optimum dosing point, but it is generally preferred to be directly upstream of the contaminated site. For example, the invention may be applied to cooling tower ponds or directly to cooling tower distribution boxes or head boxes to treat cooling water systems.

The biofilm disruptor and the oxidizing biocide may be added sequentially or simultaneously, or the components may be mixed together and added as a single composition.