HK1087094B - Method for removal of biofilm - Google Patents

Description

Method for removing biofilm

Prior Art

This application claims priority to U.S. provisional application serial No. 60/435,680, filed on 12/20/2002, which is hereby incorporated by reference.

Background

Biofilm can be defined as the undesirable accumulation of a flocculated mass of microorganisms on a surface. It is estimated that 99% of the bacteria live in biofilms worldwide. Biofilms consist of cells immobilized within a substrate, which is typically embedded in an organic polymeric matrix that is the source of the microorganisms, which limits diffusion of materials and binding to antimicrobial agents. In a flowing aqueous environment, biofilms consist of a viscous and absorbent polysaccharide matrix that encapsulates microorganisms. The bacteria in a biofilm are morphologically and metabolically distinct from free-floating bacteria. Their structural characteristics are known and can distinguish the biofilm from conventional planktonic organisms.

Biofilms have created problems in industry ranging from corrosion of water pipes to failure of computer chips. Any artificial device immersed in an aqueous environment may develop microbial biofilm colonization. For example, biofilms may be present on ship bottoms, industrial pipelines, household drains, and artificial hip joint surfaces. For industrial manufacturers, biofilm colonies represent a source of microbial growth in the system and may cause clogging problems. In water treatment plants, the creation of suspended biofilm results in a large amount of biosludge that is difficult to treat and compress during the purification process. Clumps of non-filamentous or filamentous biofilms are common, with a large population of bacteria in the floe. In addition to causing contamination, biofilms also have adverse effects on humans, including altering their resistance to antibiotics and affecting the immune system. Therefore, there is a need in the art to develop effective methods for removing biofilms.

The dynamic nature of biofilms makes it difficult to measure and monitor biofouling. Biofilms often include embedded inorganic particles such as precipitates, scale-like precipitates, and corrosion deposits. In addition, biofilms vary in thickness, surface distribution, microbial population and chemical composition, and in response to changes in environmental factors such as water temperature, water chemistry and surface conditions. Thus, the complexity of the biofilm reduces the effectiveness of the treatment and removal methods.

Even though most microorganisms in industrial systems are associated with biofilms, historically there has been less concern than planktonic microorganisms. However, various microbicides have been shown to be less effective at treating biofilms than dispersed cells of the same organism. The most common microbicides used for biofilm control are purified free halogen donors, such as NaOCl and NaOCl/NaOBr. However, these substances are effective only when used in large amounts. In addition, some recent studies evaluating the efficacy of halogens on biofilms have shown an increased resistance of attached bacteria to free chlorine disinfection. Treatment with free chlorine, which is generally effective at treating planktonic microorganism concentrations, has little effect on the number of attached bacteria or their metabolic activity. The study treated the surface, free chlorine penetration into the biofilm was the major rate-limiting factor, increasing its concentration did not improve biocidal efficacy. Griebe, T., Chen, C.I., Srinavasan, R., Stewart P., "Analysis of biofilms disinfected with monochloramine and Free Chlorine" (Analysis of Biofilm Disinfection byMonochoramine and Free Chlorine), Biofouling and bioerosion In Industrial Water Systems (edited by G.Geesey, Z.Lewandowski and H-C.Fleming), pp.151-161, Lewis Publishers (1994).

The use of Bromochlorodimethylhydantoin (BCDMH) overcomes the over-reactivity of pure free halogen donors. Studies published by m.ludyansky and f.himpler entitled "effect of Halogenated hydantoins on Biofilms" (The effect of Halogenated hydantoins on Biofilms), NACE, Paper 405(1997) demonstrated their efficacy on Biofilms higher than pure free halogen donors. However, while effective, they are still not an effective source of halogen when used in biofilms.

Others have attempted to inhibit biofilm growth in aqueous systems using an adjuvanted halogen oxide. U.S. patent No.4,976,874 to Gannon et al, incorporated herein by reference, discloses a method and formulation for biofouling control using oxidizing halogens in combination with non-oxidizing quaternary ammonium halides. However, this method causes environmental problems.

Thus, controlling biofilm in aqueous systems typically involves the addition of oxidizing and non-oxidizing biocides to a bulk water stream. However, since the concentration of microbicides in contact with various physical and chemical conditions in a particular application decreases significantly as they reach the biofilm for an extended period of time, their effectiveness decreases rapidly, thus requiring large amounts of these expensive chemicals.

Summary of The Invention

The present invention relates to a method for breaking down biofilm present in an aqueous medium and controlling odor resulting from biofilm formation. The method comprises adding to the aqueous medium one or more chlorinated hydantoins, especially monochlorodimethyl hydantoin (MCDMH) or dichlorodimethyl hydantoin (DCDMH). It is particularly important that the activity of chlorinated hydantoins on biofilms is not reduced in the presence of sunlight, since halogen-stabilized active chlorine solutions have outstanding photostability. The concentration of chlorinated hydantoin in the aqueous medium is typically maintained at about 0.01-100ppm (as Cl)₂Indicated) to inhibit biofilm.

When concentrated, the concentration of chlorinated hydantoin typically ranges from about 0.1 to 100% of the total weight.

The invention is applicable to almost all aqueous systems that contain or may contain biofilm. They may be cooling water; pulp or paper systems, bleaching water treatment, including those containing large amounts of activated sludge; and an air scrubber system; and agricultural irrigation and drainage systems; a food manufacturing or cleaning system; a brewery; dairy and meat product processing systems; and oil industry systems. The aqueous system further comprises a drinking water system; and recreational water systems, such as swimming pools and spas; domestic water related systems including toilets, drains, sewers, showers, bathtubs and sinks; and "public water related" systems, hospital systems, dental water systems, and any system in which a medical device is in contact with an aqueous medium; ornamental fountains, fish tanks, fisheries, aquaculture, and other systems where biofilm growth is encountered. The biofilm may contain different forms and kinds of pathogenic microorganisms, such as Legionella pneumophila (Legionella pneuynophila), which may or may not adhere to surfaces, such as blocks, floats or slime.

Brief Description of Drawings

Figure 1 illustrates the effect of NaOCl on Heat Transfer Resistance (HTR) associated with biofilm formation and accumulation and Dissolved Oxygen (DO) levels in aqueous systems.

Figure 2 illustrates the effect of NaOBr on Heat Transfer Resistance (HTR) and Dissolved Oxygen (DO) levels in aqueous systems.

FIG. 3 illustrates the effect of BCDMH/MEH on Heat Transfer Resistance (HTR) and Dissolved Oxygen (DO) levels in aqueous systems.

Figure 4 illustrates the effect of MCDMH on Heat Transfer Resistance (HTR) and Dissolved Oxygen (DO) levels in aqueous systems.

FIG. 5 illustrates the effect of DCDMH on Heat Transfer Resistance (HTR) and Dissolved Oxygen (DO) levels in aqueous systems.

Detailed Description

The extent and method of biofilm removal and breakdown will, of course, need to be varied depending on the problem to be solved. The diverse nature of these problems and the diverse environment in which biofilms grow require different methods and strategies for removing biofilms. For a biofilm to have established, it is often necessary to remove it rather than merely sterilize and leave it in place. Furthermore, it may be important to kill the cells that form the biofilm and prevent them from spreading elsewhere. Thus, for the purposes of the present invention, the term "breaking down" a biofilm includes removing and disrupting existing biofilm as well as preventing biofilm microorganism regrowth in the treated system. This is a more difficult task than "controlling biofilm", including preventing biofilm growth in clean systems and preventing continued growth in treated systems where biofilm has already formed.

The term "chlorinated hydantoin" refers to hydantoin in the form of a pure compound, such as monochlorodimethyl hydantoin or a mixture of hydantoins, i.e. a mixture of monochlorodimethyl hydantoin and dichlorodimethyl hydantoin, or a mixture of hydantoins with a degree of halogenation between 0.1 and 2.0.

The alkyl moieties of the chlorinated hydantoins may be the same or different, preferably the alkyl moieties contain 1-6 carbon atoms.

Preferred chlorinated hydantoins include, but are not limited to, dichloro-5, 5-dimethylhydantoin (DCDMH), monochloro-5, 5-dimethylhydantoin (MCDMH), dichloro-5-methyl-5-ethylhydantoin (DCMEH), monochloro-5-methyl-5-ethylhydantoin (MCMEH), and combinations thereof. The chlorinated hydantoin may be in the form of a solid, liquid, slurry, or gel. The term "solid" includes powders, granules, tablets, chunks and slurries.

The concentration of active ingredient of the chlorinated hydantoin concentrate is higher than typical biofilm control concentrates. For example, solid concentrates of chlorinated hydantoins typically contain 70% by weight of the active ingredient (expressed as Cl) based on 100% by total weight of the concentrate₂). In contrast, liquid concentrates of sodium hypochlorite typically contain only 12% by weight of the active ingredient, based on the total weight of the concentrate taken as 100%. Furthermore, unlike most bleaching products currently sold, the chlorinated hydantoins of the present invention are stable.

Although the above discussion relates to the treatment of biofilm-containing aqueous systems with chlorinated hydantoin, it is also contemplated that the aqueous system is formed after biofilm in a dry biofilm or non-aqueous medium is contacted with solid or granular halogenated hydantoin. In this case, the aqueous system may be formed by adding water or water vapor to the two solid or anhydrous substances.

The amount of chlorinated hydantoin added to the aqueous medium should be sufficient to break down the biofilm. This amount is generally about 0.01 to 100ppm (as Cl)₂Expressed as Cl), preferably about 0.05 to 25ppm (as Cl)₂Representation).

In addition to adding the preformed halogenated hydantoin to the aqueous system, it may be desirable to form the halogenated hydantoin in situ. This can be done by adding the hydantoin and the halogenating agent, respectively, in the appropriate molar ratio to the aqueous system containing the biofilm. For example, an alkali metal hypochlorite (e.g., NaOCl) or chlorine gas or other source of active chlorine and dimethylhydantoin may be added in a molar ratio sufficient to form the desired amount of halogenated hydantoin in situ. Broadly speaking, the molar ratio of chlorine (from the chlorine source) to alkylated hydantoin is 1: 100-100: 1, preferably 1: 10-10: 1.

In some systems, such as cooling water systems, additives are commonly used. In other systems, such as swimming pools, there may be no well-performing additive.

Performance additives (i.e., compositions that enhance the quality and effectiveness of chlorinated hydantoins) include, but are not limited to, detergents, biodispersants, solubility modifiers, compaction aids, fillers, surfactants, dyes, fragrances, dispersants, lubricants, mold release agents, detergents, corrosion inhibitors, chelating agents, stabilizers, bromine sources, and scale control agents. An important requirement is that the additive substance should be compatible with the chlorinated hydantoin composition.

Solubility modifiers that may be added to the above chlorinated hydantoins include, for example, sodium bicarbonate, aluminum hydroxide, magnesium oxide, barium hydroxide, and sodium carbonate. See U.S. patent No.4,537,697. The amount of dissolution modifying agent that can be used in the composition is from 0.01% to 50% by weight.

Examples of compression aids include carbonates, bicarbonates, borates, silicates, phosphates, percarbonates and perphosphates of lithium, sodium, potassium, magnesium and calcium cations. See U.S. patent No.4,677,130. The compression aid can be used in the composition in an amount of 0.01% to 50% by weight.

Fillers to which the chlorinated hydantoin may be added include, for example, inorganic salts such as the sulfates and chlorides of lithium, sodium, potassium, magnesium and calcium cations, as well as other inorganics such as clays and zeolites. The fillers used in the composition to reduce production costs are added in an amount of 0.01% to 50% by weight.

The biodispersant can enhance the efficacy of chlorinated hydantoins as biofilm control agents and help maintain clean surfaces of containers containing aqueous media. They are generally surfactants, and preferably surfactants that have no biocidal effect on microorganisms and biofilms. Examples of biodispersants include Aerosol OTB (sodium dioctyl sulfosuccinate), disodium lauryl sulfosuccinate, sodium lauryl sulfosuccinate, and other sulfonates. The surfactant is used in the composition to enhance its cleaning performance, and is added in an amount of 0.01-20 wt%. Typically, such mixtures contain from about 80% to about 99.99% by weight of chlorinated hydantoin and from about 0.01% to about 20% by weight of biodispersant, based upon the total weight of the mixture taken as 100%; preferably, it contains about 90-99.99% by weight of chlorinated hydantoin and about 0.01% -10% by weight of biodispersant.

Aqueous solutions of the desired non-chlorinated hydantoins in the desired molar ratios can be prepared by the methods described in U.S. patent nos. 4,560,766, Petterson, r.c. and Grzeskowiak, v., j.org.chem., 24, 1414(1959) and Corral, r.a. and Orazi, o.o., j.org.chem., 28, 1100(1963), all of which are incorporated herein by reference.

Example 1

Biofilm inhibition control efficacy

The efficacy of the microbicide containing the dispersant was estimated as the reduction in the dry weight of biofilm in the test flasks compared to the untreated control. The development of Biofilms was determined gravimetrically using the Method described in the laboratory methods for Evaluating the Efficacy of biocides against Biofilms (organic Method for Evaluating biological effectiveness on Biofilms), CoolingTower Institute, Paper TP96-07 (1996).

In this test, sheathed sphaerotheca plankton (Sphaerotilus natans) (ATCC 15291) was used, which is known to be very resistant to any chemical control and found in various applications (cooling water systems, paper water and sewage treatment processes).

The bacteria were cultured at 25-30 ℃ in 5% CGY medium containing 5g of tyrose peptone (Difco), 10g of glycerol and 1g of yeast autolysis product (Difco) per liter of DI water. About 10 per ml inoculum⁶A cell. 150ml of 5% CGY medium and 1ml of an inoculum of Phytocassium plankton (Sphaerotiussnatans) were added to an 8 oz flask. The flasks were charged with the microbiocides to be tested, i.e., NaOCl, NaOBr, MCDMH. The other flask contained no biocide as a control. The culture flask was placed on a shaker and shaken at 100-200rpm at 22-30 ℃ for 48-72 hours. The contents were dried at 105 ℃ for 5 hours and cooled overnight. The difference between the weight of the flask containing the dried biomass and the weight of the flask itself represents the quality of the dried biofilm.

The efficacy in preventing biofilm was calculated according to the following formula, expressed as percent change in growth based on the difference between the average weight of dried biofilm in the untreated control flask and the treated flask:

E％＝(B_{control average}-B_Average)/B_{Control average}×100

Wherein E%: percentage of biofilm growth reduction, B ═ biofilm weight_ControlBiofilm weight in control flasks.

The results of this embodiment, including the concentration of the microbiocide, are listed in table 1.

TABLE 1

Microbicide	Concentration, ppm	B，g	B，g	E，％
					NaOCl	10	0.0028	0.0185	84.86
NaOBr	10	0.0013	0.0185	92.97
					MBDMH	10	0.0008	0.0185	95.7
MCDMH	10	0.0005	0.0185	97.3
					DCDMH	10	0.0005	0.0173	97.1
NaOCl	5	0.009	0.0144	37.5
					NaOBr	5	0.0021	0.0144	85.4
MBDMH	5	0.0081	0.0152	46.7
					MCDMH	5	0.0007	0.0144	95.1
DCDMH	5	0.0009	0.0173	94.8

The results show that chlorinated hydantoins (MCDMH) are superior biofilm inhibitors to free halogen donors (NaOCl or NaOBr).

Example 2

Control efficacy of biofilm removal

Phytoplankton (Sphaerotilus natans) (ATCC 15291) was used in the following assay as described in example 1.

Biological membrane test system

An on-line test system for determining the efficacy of chlorinated microbiocides is employed to provide a real-time, non-destructive method of monitoring and measuring biofilms. The system can monitor Heat Transfer Resistance (HTR) associated with biofilm formation and accumulation, as well as Dissolved Oxygen (DO) levels in water associated with changes in biofilm activity. The design, parameters and growth conditions of this System are described in Ludenssky, M., "Automated System for measuring microbiocides on Biofilms (An Automated System for biological Testing on Biofilms)" Journal of Industrial Microbiology and Biotechnology, 20: 109-115(1998).

The system consists of a continuous flow heat exchange loop, a biological growth reactor (chemostat) and incubator, biofilm measurement devices, and environmental controls. All system parameters, including water flow, temperature, dilution rate, and nutrient concentration, have been optimized for rapid, large-scale, and reproducible biofilm growth. The system provides circulating water (make-up water) and maintains constant oxygen saturation (by continuously sparging air), temperature and pH conditions. Thus, any change in the dissolved oxygen concentration or pH level of the circulating water is believed to be due to biofilm activity. All monitoring and control parameters are calculated in a data acquisition system that is controlled by a user designed computer software program. Data were collected every 15 seconds, and averages were calculated every 3-60 minutes in the diffusion table and recorded for subsequent graphical analysis. The program was designed to enable the system to operate continuously for several weeks under constant conditions. Microbiocide efficacy determinations are made by analyzing and comparing the shape and measurements of the corresponding curves for HTR and dissolved oxygen. The analysis includes consideration of the corresponding pattern of curves for biocide treatment, and the reproduction (regrowth) of biofilm.

Growth conditions

The biofilm growth test was performed by selecting sheathed sphaerotheca plankton (sphaerotheca natans) (ATCC 15291), which is known to form a persistent biofilm on the surfaces of cooling water systems and heat exchangers of paper machines. The inoculum was pumped into the microbial growth reactor and allowed to stand overnight at room temperature. The next day, circulating water and nutrients (CGY medium) were added. The initial growth conditions and parameters of the system are selected based on previous experiments, laboratory constraints, the geometry of the system components, and the need to promote biofilm growth. By reducing the medium concentration to 5% or less and maintaining the dilution rate higher than the maximum rate, the growth conditions for planktonic growth can be changed to those for adherent filamentous growth. The test conditions are listed in table 2.

TABLE 2

Online testing condition of biological membrane system

Parameter(s)	Condition
		pH	7.2-8.5
Temperature of circulating water	74-76℉
		Wall temperature	85℉
Circulating water	Clinton tap water
		Concentration of substrate	CGY；30-70ppm
Inoculum	Phytoplankton sp
		Velocity of water flow	3fps
Dilution ratio	0.9
		Circulating water	170ml/min
Nutrient addition	1ml/min
		Volume of the system	10 liters of water

The biocidal efficacy of the test solutions was determined by analyzing the HTR and dissolved oxygen curve shapes representing the biofilm's reaction to the biocidal treatment.

Process of treatment

During the treatment, the system was continuously fed with nutrients and recycled water (containing constant chemicals, oxygen and temperature). Three treatment modes were measured, called segmentation (slug), segmentation + continuation, and continuation, respectively.

The staging is performed by adding a pre-calculated amount (volume of circulating water per liter of system) of the prepared stock solution to the chemostat. In the split-plus-continuous mode, biocide treatment is carried out by injecting an initial split dose to overcome the halogen requirement, followed by continuous treatment at a constant concentration for 3 hours, depending on the circulating water rate.

Preparation and monitoring of microbicides

Five microbicides were prepared: NaOCl, NaOBr, MCDMH, BCDMH/MEH and DCDMH as 1000ppm fresh Cl₂Master solution (master solution). Treatment concentrations for all biocides were calculated by measuring free halogen and total residual halogen, immediately prior to treatment, using DPD Cl₂And (4) testing and measuring.

NaOCl, NaOBr, MCDMH, BCDMH/MEH and DCDMH were tested for elevated initial concentrations (10, 15 and 20ppm) for 3 consecutive days, including repeated fragmentation + sequential treatment. The heat transfer rate and dissolved oxygen level of the system can be automatically monitored while analyzing their kinetics. The following conclusions can be drawn from the parameters obtained. :

NaOCl, NaOBr and BCDMH/MEH were not able to remove biofilm at any of the concentrations tested. Biofilm recovery was observed both 24 hours after the start of each treatment and when the HTR value was higher than the start of each treatment, as shown in figures 1, 2 and 3.

The dissolved oxygen response to biocide treatment was strongest in DCDMH and weakest in NaOCl. By curve pattern analysis (fig. 1-5), the conclusion is: control of biofilm regrowth was achieved with 15ppm BCDMH/MEH or 20ppm NaOBr fragmentation + continuous treatment as shown in figures 2 and 3. However, none of these biocides are able to remove biofilm.

The chlorinated hydantoins MCDMH and DCDMH tested showed a unique effect: biofilm detachment occurred immediately after addition of 20ppm of MCDMH or DCDMH. The results of this experiment are shown in fig. 4 and 5. This effect is not present in any other oxidizing biocides.

The following table summarizes the above observations:

TABLE 3

Segmented + continuous processing

Biological membrane	Control	Biological membrane	Removing
					HTR	DO	HTR
NaOCl	Invalidation	Weakest point	No
				NaOBr	Effective at 20ppm	Medium and high grade	No
BCDMH/MEH	Effective at 15ppm	Medium and high grade	No
				MCDMH	Effective at 15ppm	Medium and high grade	At 20ppm removal
DCDMH	Effective at 15ppm	Strongest power	At 20ppm removal

Example 3

This example demonstrates the enhanced photostability of MCDMH when the test solution is exposed to simulated sunlight, as compared to NaOCl.

Test solutions were prepared by adding NaOCl and MCDMH (concentrations shown in Table 4 below) to tap water at 22 ℃ and pH 7.8. These solutions were illuminated with UVA-340 fluorescent lamps that simulate the solar radiation on the earth's surface. The test sample was covered with a crystal plate transparent to ultraviolet light to prevent evaporation. The total halogen concentration as a function of time was determined. The resulting active halogen decay curve was analyzed using a first order kinetic algorithm (first order kinetic algorithm) and the corresponding active halogen half-life calculated. The results are shown in table 4.

As shown in table 4, MCDMH provides significantly better photostability than NaOCl. The observed active halogen half-life of MCDMH was 108 hours, while NaOCl was only 1.1 hours.

TABLE 4

Photolysis of MCDMH and NaOCl solutions

Time variation (hours)	Total halogen (Cl)Ppm of
			NaOCl	MCDMH
	0	4.0			5.9
1.5			1.1	5.6
	6.5	0.07			5.3
29.5			-	4.1
	52.5	-			3.1
100			-	2.3
	187	-			1.5
267			-	1.0
First order half-life (hours)			108	1.14

These data clearly show that the activity of MCDMH was barely reduced in the first 6.5 hours and retained significant activity during the study, while the activity of NaOCl was significantly reduced in the presence of simulated sunlight. The comparative half-lives further show the significant photostability of the chlorinated hydantoins.

Example 4

Hydantoin-stabilized active chlorine solutions can also be produced by mixing hydantoin with NaOCl. As shown in fig. 2, the mixture of DMH and NaOCl resulted in even greater light stability than the mixture of cyanuric acid, a well-known chlorine light stabilizer used in the recreational water market. The test conditions were the same as those of example 3.

TABLE 5

Photostability of hydantoin and cyanuric acid stabilized hypochlorite solutions

Time variation (hours)	Total halogen (Cl)Ppm of
			NaOCl30ppm DMH	NaOCl +30ppm Cyanuric acid
	0	4.6			4.3
1.5			4.3	4.1
	6.5	4.05			3.6
29.5			3.6	2.0
	52.5	3.0			0.78
100			2.2	0.07
	187	1.68			-
267			1.19	-
First order half-life (hours)			141	17

The data in table 5 show that DMH significantly enhances the photostability of NaOCl, and that the mixture performs better than NaOCl and cyanuric acid. The observed active halogen half-life of the NaOCl + DMH stabilized solution was 141 hours, while the cyanuric acid stabilized NaOCl was only 17 hours.

Claims (13)

1. A method of decomposing a bulked bioactive sludge or biofilm in an aqueous system, said method comprising forming in situ in said aqueous medium containing bulked bioactive sludge or biofilm one or more chlorinated hydantoins in an amount sufficient to convert such chlorinated hydantoins in said aqueous medium to Cl₂Expressed as a concentration of 0.01-100ppm, wherein the chlorinated hydantoin is formed in situ by adding chlorine from an active chlorine source and an alkylated hydantoin to the aqueous medium containing a bulked bioactive sludge or biofilm, the added chlorine and the alkylated hydantoinThe molar ratio of urea is 1: 100 and 100: 1.

2. The method of claim 1, wherein the chlorinated hydantoin is monochlorodialkylhydantoin, dichlorodialkylhydantoin, or a mixture thereof, wherein each of the above alkyl groups contains 1 to 6 carbon atoms.

3. The method of claim 2, wherein the chlorinated hydantoin is monochlorodimethyl hydantoin, dichlorodimethyl hydantoin, or a mixture thereof.

4. The method of claim 1, wherein the treated aqueous medium is exposed to sunlight.

5. The method of claim 1, wherein the molar ratio of chlorine to alkylated hydantoin is from 1: 10 to 10: 1.

6. The method of claim 1, wherein the aqueous medium comprises a biofilm adhered to a substrate.

7. The method of claim 1, wherein the chlorinated hydantoin is added with a performance additive.

8. The method of claim 7 wherein the performance additive is a dispersant, biodispersant, scale control agent, corrosion inhibitor, surfactant, biocide, detergent, or mixtures thereof.

9. The method of claim 1, wherein the aqueous system is a cooling water system, a pulp or paper making system, an air washer system, an agricultural irrigation and drainage system, a food manufacturing or cleaning system, an oil industry system, a drinking water system, a domestic water related system, or a public water related system.

10. A method of removing biofilm from a substrate in an aqueous medium, said method comprising: monochlorodimethyl hydantoin, dichlorodimethyl hydantoin, or a mixture thereof, in situ in the aqueous medium in an amount sufficient to convert the chlorinated hydantoin to Cl₂Expressed as a concentration of 0.05 to 25ppm, wherein the chlorinated hydantoin is formed in situ by adding chlorine and dimethyl hydantoin from an active chlorine source to the aqueous system in a molar ratio of chlorine to dimethyl hydantoin of from 1: 10 to 10: 1.

11. The method of claim 10, wherein the chlorine source is sodium hypochlorite or chlorine gas.

12. A method of decomposing a bulked biologically active sludge in an aqueous medium, the method comprising: monochlorodimethyl hydantoin, dichlorodimethyl hydantoin, or a mixture thereof, in situ in the aqueous medium in an amount sufficient to convert the chlorinated hydantoin to Cl₂Expressed as a concentration of 0.05 to 25ppm, wherein the chlorinated hydantoin is formed in situ by adding chlorine and dimethyl hydantoin from an active chlorine source to the aqueous medium in a molar ratio of chlorine to dimethyl hydantoin of from 1: 10 to 10: 1.

13. The method of claim 12, wherein the chlorine source is sodium hypochlorite or chlorine gas.