NZ620230B2 - Use of sulfamic acid or its salts as stabilizers especially in combination with ammonium salt and/or ammine for bleach or other halogen containing biocides in the paper area - Google Patents

Abstract

Disclosed is a method of preventing the growth of microorganisms in a paper making process water stream comprising treating the water stream with a composition comprising: a halogen source, urea, and an additional sulphur bearing halogen stabilizer such as sulfamic acid, wherein the molar ratio of sulfamic acid to halogen atoms in the halogen source is 2:1. In certain embodiments the halogen source is selected from the group consisting of: chlorine, sodium hypochlorite, 1,3,5-Trichloroisocyanuric acid (TCCA), 1-bromo-3-chloro-5,5-dimethyl-2,4-imidazolidedione (BCDMH) and 1,3-dichloro-5,5-dimethyl-2,4-imidazolidedione (DCDMH). ulfamic acid to halogen atoms in the halogen source is 2:1. In certain embodiments the halogen source is selected from the group consisting of: chlorine, sodium hypochlorite, 1,3,5-Trichloroisocyanuric acid (TCCA), 1-bromo-3-chloro-5,5-dimethyl-2,4-imidazolidedione (BCDMH) and 1,3-dichloro-5,5-dimethyl-2,4-imidazolidedione (DCDMH).

Description

USE OF SULFAMIC ACID OR ITS SALTS AS STABILIZERS ESPECIALLY IN COMBINATION WITH AMMONIUM SALTAND/OR AMMINE FOR BLEACH OR OTHER HALOGEN CONTAINING BIOCIDES IN THE PAPER AREA Cross-Reference to Related Applications Not Applicable.

Statement Regarding Federally Sponsored Research or Development Not Applicable.

Background of the Invention At least one invention pertains to compositions and methods for reducing biological activity in process streams, e.g. water based process streams. Biological ty in process s is problematic for a variety of reasons, including, but not d to sanitation ms, process equipment efficiency problems, and product quality problems. For e, in papermaking processes, high biological activity levels have a rious effect on equipment operation. The problems associated with manufacturing certain paper types, e.g. tissue/recycled products, are more pronounced, because high fungal levels present the quandary of providing a biocide program that stabilizes the biocide well enough so that it is not readily ed (good persistence) and providing a biocide at sufficient levels to combat periodic spikes in ical activity - a need for less stabilization/decreased persistence. Moreover, ing/processing of recycled fiber ts the additional quandary for papermakers because papermakers are balancing the addition of sulfite post bleaching/processing of recycled fibers, which quenches a halogen, e.g. chlorine, with the need to maintain chlorine in the system, more ically, a persistent level of chlorine in the papermaking system without having to add more halogen/chlorine than is necessary. Thus, there is a need for a further refinement of biocidestabilizer formulations and delivery ols, which can treat systems more effectively and in an environmental friendly manner, such as using less ne/halogen, which in turn reduces halogen by-product formation.

At least one invention relates to methods and compositions ive at stabilizing oxidant biocides. Oxidant es such as peroxide acid and halogen chemicals like sodium hypochlorite have been widely used in the pulp and paper industry. These oxidant biocides are highly effective at immediately killing large numbers of microorganisms. Unfortunately, after their introduction into process water systems, t biocides are not naturally stable and they tend to e rapidly and over time lose their effectiveness. In environments with very high populations of microorganisms such as in process water which is rich in organic and inorganic al on which the microorganisms can feast, sufficient numbers of microorganisms can survive until after the oxidant biocides have lost iveness. As a , unless there is sufficient residual biocide present, the microorganism population will soon recover from an oxidant e treatment. In some cases, halogen tolerant bacteria strains develop due to repeated introduction of single oxidant biocide. This can result in systems suffering from out of control bacterial growth. (See for example the textbook: Disinfection, Sterilization, and Preservation, Fifth Edition, by Seymour S. Block, Lippincott Williams & Wiikins, (2001) at least in pp. 3 1-57).

This problem is compounded by the fact that repeated ations of oxidant biocides is in many contexts, not commercially feasible. Many oxidant biocides cause e effects on paper brighteners, dyes, and other additives required to produce commercially acceptable paper products. Repeated introduction of oxidant biocides can also corrode many pieces of papermaking machinery.

One technique used to address this problem is to stabilize the oxidant biocides allowing them to suppress the ity of microorganisms over a long time while weakening the negative impact that the oxidant biocides have on the resulting paper and the papermaking ent. As bed in US Patents 3,328,294, 3,749,672, 3,170,883, 9 and 7651622 previous attempts at stabilizing t biocides included the use of sulfamic acid, sulfamate stabilized chlorine, monochloramine, DMH stabilized halogen, AmBr-Cl 2, and organic nitrogen stabilized ne. While somewhat stable, these attempts have proven to be less effective biocides than desired. N-hydrogen sources have also been used to stabilize oxidant biocides but they too have been unsatisfactory because they are volatile and too rigid in their dosage requirements. This rigidity prevents the kind of flexible molar ratio adjustments that are often required to suit the specific conditions of the particular water system they are used to treat.

Therefore there is a clear need and utility in an enhanced stabilized halogen biocide which is effective, ible with other biocides, and flexible in dosage and concentration.

Another technique to address this problem is described in US Published Patent ations 2006/023 150 A and 2003/00298 12A1 where they disclose the use of biocide blends. Such blends typically include an t halogen which provides an l large kill of the organisms and another longer lasting but less effective biocide which provides more long term microorganism suppression. Unfortunately many biocides are lves incompatible with other biocides and the use of multiple biocides, each having their own preparation and introduction issues, requires an inordinate investment in complex application equipment.

Furthermore, multiple biocide feeding machines be led at various points along a papermaking production line thereby vastly increase the cost and complexity of adding the biocides. So there s need for fied making biocide and feeding approach.

The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is "Prior Art" with respect to this invention, unless ically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR § ) exists.

Brief Summary of the Invention At least one embodiment of the ion is directed to a ition comprising: a halogen source, urea, and an additional halogen stabilizer excluding urea, optionally an alkali in a concentration sufficient to provide said composition with a pH of greater than 10. Optionally the composition es a stabilized bromine compound. The stabilizer may comprise one item from the list consisting of: an N-hydrogcn compound, a, ammonium salts, ammonium sulfamate, ammonium sulfate, sulfamic acid, sodium sulfamate, cyanuric acid, succinimide, urea, glycouril, glycine, amino acids, and any combination thereof. The stabilizer may comprise at least two compositions of matter each of which function as a halogen stabilizer. The halogen source may be selected from the group consisting of at least one of the following: a chlorine source, an alkaline hypohalite, Cl2 gas, NaOCl, Ca(OCl) 2, and electrically generated chlorine.

The composition may contain: an alkaline hypohalite, urea, and um sulfamate. The urea and additional halogen stabilizer may be in a ratio of 50:50 with one another.

At least one embodiment of the invention is directed to a method for reducing biological activity in a process stream sing providing the composition to a s stream.

The composition may be added to the process stream by the following mode of addition: forming a mixture of at least an alkali in a concentration sufficient to maintain a pH of greater than 10 in the final composition and an alkaline lite, and arily mixing said mixture with a second mixture containing urea and said additional stabilizer, wherein said secondary mixing is optionally done with a T-mixer. The process stream may be a papermaking process . The papermaking process may be a process selected from the group consisting of: tissue and/or towel, board; packaging; pulping; and recycled g. The process stream may contain fungus.

The process stream may have a sulfite concentration of between 2 ppm to 50 ppm. The method may further comprise monitoring the biological activity in the process stream prior to and subsequent to the addition of said ition. The biological activity may be monitored by taking a sample of said process stream and plating said sample on a Petri dish or similar apparatus or by measuring ATP levels of a sample from the process stream or by taking a sample of said process stream and monitoring dissolved oxygen and optionally the oxidation reduction potential of said sample and optionally ding by adding or reducing the amount of one or more chemistries which are added to said process stream, wherein said chemistries include said composition. The method may further comprise adding a second composition to said process stream that contains a halogen, urea, and excludes an additional N-hydrogen compound.

At least one embodiment of the invention is directed to a method of preventing the growth of rganisms in a process water stream. The method includes the step of: introducing a composition into the process water stream. The ition ses: a halogen source, a halogen stabilizer ning a mixture of a sulfur bearing species with urea and/or ammonium sulfate at any ratio, and optionally an alkali. The sulfur bearing species es sulfamic acid or its salt lent. The molar ratio of sulfamic acid to halogen atoms in the halogen source is more than 2:1.

The sulfur bearing species may further comprises a nitrogen stabilizer. The nitrogen stabilizer may be one item selected from the group consisting of ammonium sulfate, sodium sulfamate, and any combination thereof. The molar ratio of halogen to all of the sulfur in the sulfur bearing species may be more than 2:1. The alkali may be sodium hydroxide. The n may be chlorine, sodium hypochlorite, 1,3,5-Trichloroisocyanuric acid (TCCA), 1- bromochloro-5,5-dimethyl-2,4-imidazolidedione (BCDMH) and l,3-dichloro-5,5-dimethyl- 2,4-imidazolidedione (DCDMH). The method may further comprise the steps of first adding to the sulfamic acid an alkali and then the adding urea and/or sodium sulfate.

The process water stream may be so rich in food for microorgasnisms that a single halogen oxidant e is not effective at exterminating the microorganisms population but the composition is. The process water stream may be one selected from the list consisting of a cooling tower water stream, and papermaking process water stream. The ratio of sulfamic acid or its salt to nitrogen izer may be optimized at any ratio between the concerns of biocidal efficacy and impact on chemical additive present in the process water stream. The ratio of sulfamic acid or its sail to en stabilizer may be optimized at any ratio between the concerns of biocidal efficacy and ion on equipment present in the process water stream. The ition when used in a papermaking process might not reduce the effectiveness of OBA and DYE additives on paper made from that process. The salt may be sodium sulfamate.

Additional features and advantages are described herein, and will be apparent from, the following Detailed Description.

Brief Description of the Drawings A detailed description of the invention is hereafter bed with specific reference being made to the gs in which: is a flowchart illustrating one method of combining constituents of the biocide ition. is a second flowchart illustrating one method of combining constituents of the biocide ition. is a third flowchart illustrating one method of combining constituents of the biocide composition. is a graph displaying data which demonstrates the effectiveness of the invention.

Detailed Description of the Invention The following definitions are provided to determine how terms used in this application, and in particular how the claims, are to be construed. The organization of the definitions is for convenience only and is not intended to limit any of the definitions to any particular category, "Alkali" means a composition of matter that functions as a pH altering chemical base.

"DYE" or "Dye" means one or more itions used in the papermaking ry to alter the optical properties of a substrate. Dyes often contain chromophoric groups and auxochrome and have good affinity to fiber and compatibility to other additive in paper industry.

"Nitrogen stabilizer" means a stabilizer which contains at least one nitrogen atom.

"OBA" means a dye or pigment based optical brightening agent which is a component of a g formulation ly applied to a paper substrate. Dyes or pigments that absorb ultraviolet radiation and reemit it at a higher frequency in the visible spectrum (blue), thereby effecting a white, bright ance.

"Pigment" means a solid material used in a papermaking process to alter the l properties of a substrate.

"Halogen Source" means a halogen atom by itself or a halogen atom associated with a ic counterpart.

"Halogen Stabilizer" means a halogen based material whose presence in ity to a composition of matter functioning as an oxidizing biocide increases the amount of time that the composition remains in a sufficient chemical state to continue functioning as a e, this includes but is not limited to materials which preserve (or slow down the rate of loss of) the oxidizing capability of the e composition.

"Stabilizer' means a composition of matter that increases the length of time that oxidizing n ions retain oxidant capacity and are capable of releasing free ions slowly thereby remaining an effective biocidal agent in a liquid environment. rate'''means a sheet of paper, a sheet of paper precursor, a mass of fibers, or any other cellulose based or synthetic fibrous material that can be coverted into a sheet of paper by a papermaking process.

In the event that the above definitions or a description stated elsewhere in this application is inconsistent with a meaning (explicit or implicit) which is commonly used, in a dictionary, or stated in a source incorporated by reference into this application, the application and the claim terms in particular are understood to be construed according to the definition or description in this application, and not according to the common definition, dictionary definition, or the definition that was incorporated by reference. In light of the above, in the event that a term can only be tood if it is ued by a dictionary, if the term is defined by the Kirk-Othmer Encyclopedia of Chemical Technology, 5th n, (2005), (Published by Wiley, John & Sons, Inc.) this definition shall control how the term is to be defined in the claims.

As stated above, the t invention provides for a composition and a method of use for said composition, which reduces biological activity in a process stream by providing a more efficient application of a biocide. In turn the biocide is more ently utilized, e.g. increase in persistence of the biocide in the system when needed, which can provide an environmental benefit because a process or can use less e to combat various types of microorganisms and bacteria that pervade process streams, e.g. including water based systems, wherein one water based system example is a papermaking system.

The composition contains at least the following components: halogen, urea, and an additional halogen stabilizer excluding urea. izers can be blended with chlorine or bromine to yield a milder oxidant. Benefits of halogen-stabilization include increased persistence of the halogen residual for improved control of microbial growth in biofilm or surface deposits and in systems with long residence times and high halogen demand.

Halogen-stabilization can also improve compatibility of the halogen with sensitive process additives, including dyes, optical ening agents, polymers, and corrosion control products. However, it has been observed in several instances that the halogen becomes too persistent when it is d with izers, for example urea. As a result, the program may not adequately control fungi and several types of bacteria, ing sphingomonads and sporeforming bacteria. Some forms of stabilized-halogen are more volatile, reducing the n residual available in the water-phase and contributing to phase corrosion.

In at least one embodiment optionally, there is an additional component: an alkali in a concentration sufficient to provide a pH of greater than 10. In at least one embodiment, the pH is greater than 12. In yet a further embodiment, the pH range is from 12 to about 13.5. An alkali can include one or more of the following chemistries: sodium hydroxide and potassium hydroxide. ally, there is an additional component: excluding a stabilized bromine compound from said composition.

With respect to the n, in at least one embodiment, the halogen is selected from at least one of the following: a chlorine source, alkaline hypohalite, ¾ gas (e.g. added to stream prior to blending), NaOCl, Ca(OCl)2, and electrically ted chlorine.

In at least one ment the composition comprises urea in combination with additional stabilizer, including um Sulfamate, to ize halogens for biocontrol In at least one embodiment, the stabilizer is an N-hydrogen nd.

In at least one embodiment, the N-hydrogen compound is ammonium sulfamate.

In at least one embodiment, the N-hydrogen compound excludes ammonium sulfate.

In at least one embodiment, the composition contains: an alkaline hypohalite, urea, and ammonium sulfamate.

The ratios between urea and an additional stabilizer can vary depending upon system conditions, e.g. levels of fungus. For e, one could take into account chemical kinetics between: (a) urea with halogen; (b) onal stabilizer with halogen; and (c) blend of urea and additional stabilizer with halogen.

In at least one embodiment, the stabilizer blend between urea and the additional stabilizer is 50:50.

A method for reducing biological activity in a process stream is also disclosed, e.g. process stream contained in a water system. The method comprises: providing a composition to a process stream, wherein said composition contains: a halogen, urea, and an onal izer excluding urea, optionally an alkali in a concentration sufficient to provide said composition with a pH of greater than 10; and optionally excluding a stabilized bromine compound from said composition.

In at least one embodiment, the composition is added to the process stream by the following mode of addition: forming a mixture of at least an alkali in a concentration sufficient to provide a pH of greater than 0 and an alkaline hypohalite, and secondarily mixing said mixture with a second mixture containing urea and said additional stabilizer, wherein said secondary mixing is optionally done with a T-tnixer.

In at least one embodiment, the method comprises: adding a second composition to said s stream that contains a halogen, urea, and excludes an onal N-hydrogen compound.

With t to the order of addition of the components, In at least one embodiment, the composition is added to the process stream by the following mode of addition: forming a mixture of at least an alkali in a concentration sufficient to provide a pH of greater than , ably 12 to 13.5, and an alkaline hypohalite, and secondarily mixing said mixture with a second mixture containing urea and an additional stabilizer. One of ordinary skill in the art could mix the first mixture and second mixture via a variety of techniques, e.g. apparatuses.

In at least one embodiment, the first mixture and second mixture are mixed together with a T-mixer. One of ordinary skill the art would understand what a T-mixer is.

In at least one embodiment, one of ordinary skill in the art can utilize a mixing chamber, such as the one disclosed in U.S. Patent No. 7,550,060, herein incorporated by reference, to carry out a mixing protocol of the chemistries.

The methodology of the present invention is applicable to a y of process streams or aqueous based systems or water based systems or industrial based systems or a combination f.

In at least one ment, the process stream is a papermaking process .

In at least one embodiment, the papermaking process is a process ed from the group consisting of: tissue and/or towel, board; packaging; pulping; and recycled pulping.

In at least one embodiment, the process stream contains fungus. n at least one embodiment, the process stream has a sulfite concentration of between 2 ppm to 50 ppm.

The efficacy of the composition for reducing biological activity can be measured by a variety of analytical techniques and controls schemes.

In at least one embodiment, the process stream further comprises monitoring said biological activity in said process stream prior to and subsequent to the addition of said composition.

In at least one ment, the biological activity is red by taking a sample of said process stream and plating said sample on a Petri dish or similar apparatus.

In at least one ment, the biological activity is monitored by measuring ATP (adenosine triphosphate) levels of a sample from said process stream.

In at least one ment, the ical activity is monitored by taking a sample of said s stream and monitoring dissolved oxygen and optionally the oxidation reduction potential of said sample and optionally responding to said biological activity by adding or reducing the amount of one or more chemistries which are added to said process stream, wherein said chemistries include said composition.

The compositions by themselves or compositions utilized to treat a process stream can be made outside of the process stream or within the process stream (in situ) or a combination thereof.

In at least one embodiment a composition comprising a halogen, a halogen stabilizer, and ally an alkali are provided for inhibiting the growth of microorganisms in a aking environment. The stabilizer is a composition comprising sulfur. The sulfur bearing species includes sulfamic acid (or its salt equivalent such as sodium ate). The molar ratio of the halogen to the sulfamic acid is more than 2:1. By having such a large ratio of halogen to izer, it has been observed that an unexpected biocidal effect occurs. This was quite surprising as at a molar ratio of 1:1 of halogen to sulfamic acid, no significant anti-biological efficacy was observed. Moreover because the stabilizers are needed to stabilize the halogens, it would be expected that more stabilizer relative to halogen would better stabilize the halogen, yet the opposite is the case.

In at least one embodiment the stabilizer is a composition comprising a mixture of sulfur bearing species with urea. The halogen is mixed with ic acid at molar ratio of Nitrogen to Chlorine of more than 2:1. By having such a stabilizer mixture of stabilized halogen, it has been observed that an unexpected synergistic effect occurs which results in the halogen remaining stabilized for a longer period of time, and without impairing the quality of the produced paper or corroding the papermaking equipment.

In at least one embodiment the stabilizer is a ition comprising a mixture of sulfur bearing species with um sulfate.

In at least one embodiment the sulfur bearing species further comprises a en stabilizer.

In at least one embodiment the en stabilizer is one item selected from the group consisting of ammonium sulfate, sodium sulfamate, or any combination f.

In at least one embodiment the molar ratio of n to all of the sulfur in the sulfur bearing species is more than 2:1.

In at least one embodiment the alkali is sodium hydroxide.

In at least one embodiment the halogen are chlorine, sodium hypochlorite, 1,3,5- oroisocyanuric acid (TCCA), l-bromochloro-5,5-dimethyl-2,4-imidazolidedione (BCDMH) and l,3-dichloro-5,5-dimethyl-2,4-imidazolidedione (DCDMH).

In at least one ment the sulfamic acid is first amended with alkali and then the urea/ammonium sulfate is added. Sodium hypochlorite is added to above mixture.

In at least one embodiment the sulfur baring nitrogen combined sodium hypochlorite first at molar ratio more than 2:1 nitrogen to chlorine and then is added to urea or ammonium sulfate.

In at least one embodiment the urea or ammonium sulfate combined sodium lorite first then is added to sulfur baring en at different ratio. The order is significant because different stabilized halogen species are generated at different rates due to ing equilibrium constants. These ences can be accounted for by dosing the halogens in different amounts and in different orders. Also chlorine is able to transfer from stabilized chlorine to other nitrogen species so the order of combinations can compensate for that.

In at least one embodiment the composition contains no buffer.

In at least one embodiment the composition contains no alkali.

In at least one embodiment the composition can be ated on site by xing the components together before mixing with halogen oxidant.

In at least one embodiment the composition can be formulated on site by mixing the components as illustrated in any one of FIGs 1, 2, and/or 3.

In at least one embodiment the microorganisms killed by the biocide are sessile.

In at least one embodiment the microorganisms killed by the biocide are onic.

One noted benefit of the invention is the fact that the sulfamic acid and the nitrogen stabilizer readily combine so when mixing the two a high product yield is achieved with little waste. In addition, unlike stand alone stabilizers containing inorganic en stabilizers, the e of sulfamic acid and nitrogen stabilizer functions at many ent ratio amounts. As a result the relative amounts of sulfamic acid or nitrogen stabilizer can be appropriately increased o decreased depending on the particular environment it is to be used in. For example in cases where en stabilizer may ere with particular paper additives such as OBA or DYE, the relative amount of sulfamic acid will be increased. In contrasts in contexts where the sulfamic acid has compatibility , the amount of nitrogen stabilizer can be increased.

In at least one embodiment the details of the formulation is targeted towards the nature of the biological infestation. For example if bacteria are just beginning to infiltrate one or more items of process equipment, a formulation containing relatively equal amounts of sulfamic acid and the nitrogen stabilizer is used because it is optimized to causes low impact on additives and low degrees of corrosion which is more desirable than a highly effective biocide when the infestation is weak. In contrast, when the contamination is intense or long term colonization, effectiveness of the biocide is more important than the one time effects on additives or corrosion and a therefore a formulation containing more sulfamic acid relative to the molar amount of nitrogen stabilizer is used. Thus by using a formulation having only two les, a number of ion specific ratios can be provided which requires a simple input system yet is capable of dynamically responding to different conditions over the life cycle of the industrial facility.

In at least one embodiment the composition is used as a biocidal agent in a cooling tower.

In at least one ment the composition is used to reduce biofilm on a surface.

Biofilm is the accumulation of sessile organisms on the surfaces of equipment. Such accumulations often pose particular problems as the available d surface area for the biocide to work on is reduced. Moreover there is often a tradeoff between e efficacy and impact the biocide has on biofilms yet the invention avoids harmful effects on process equipment yet effectively lizes biofilms.

In at least one embodiment the composition is used to treat rganisms in a membrane system. Membrane systems are often prone to biofilm colonization as microorganisms find their surfaces (because of composition, shape, or both) attractive. As they are also very delicate relative to other forms of process equipment, the general tradeoff issues are even more pronounced in membranes. Fortunately the composition is ive at treating membrane biofilms without damaging them. In at least one embodiment the membrane system is a water ble membrane. In at least one embodiment the membrane is a part of a water treatment .

In at least one embodiment the composition has a particular pH before it is introduced into the system hi at least one embodiment the pH is greater than 5 and less than 12, and is most preferably between 8 and 10.

In at least one ment the ratio of the contents of the composition are balanced to optimize the composition's effectiveness and utility. In the prior art sulfamate was used in a ratio of 1:1 with chlorine. This resulted in stronger than d bonding of the chlorine and as a result it reduced the rate of releasing sulfamate from sulfate thereby reducing the effectiveness of the composition. In at least one embodiment the ratio is different and as a result the composition is more effective. In at least one embodiment the ratio of sulfamate to stabilizer within the composition is n (less than 4):1 and (more than 1): 1. Experimental data has shown that in some circumstances ratios of :1 and 4 :1 do not work at all or at best work poorly, ratios of 8 :1 to 4 :1 work somewhat and that 3: 1 is highly effective as a biocide. This demonstrates that an unexpected sysnergistic effect based on more than just concentration is at work which is wholly novel and unexpected.

EXAMPLES The foregoing may be better understood by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the invention.

A number of biocide formulations were prepared and were applied to samples of process water from a paper mill. Their compositions and effectiveness are listed in and in Table 1. Table 1 illustrates that a composition comprising 12% Sulfamic Acid and 3% Ammonium Sulfate is able to achieve high product yield without addition of NaOH. It also demonstrates that the addition of NaOH i bleach can improve ility of ng stabilizers at different rates.

Optimization of Mending condition for mixing izer and sodium hyp c l ite **AS : ammonium sulfate *** O : total residual oxidant **** FE.O : free residual oxidat Table 1 illustrates that 12% Sulfamic Acid and 3% ammonium sulfate showed more active on ivity inhibition than other combinations of stabilizers.

Without being limited in theory and the scope afforded in construing the claims, it is believed that naturally the ne transfers back and forth from one chloronitrogen species to another chloronitorgen species according to the equilibrium ons below and the invention makes use of the different equilibrium constants to optimize the presence of the desired ons that produce the particularly desired chloronitrogen species that is effective as a bidcide.

H 2NS0 H +NaOCl ClHNS0 H +NaOH ClHNS0 H +NaOCl Cl NS0 H +NaOH NH )2S0 +INaOCl = 2NH Cl +Na S0 +2H 0 NH Cl +NaOCl NHCl +NaOH H NS0 H +NH Cl ClHNS03H +NH OHNS0 H +NH Cl => Cl NS0 3H +NH3 In at least one embodiment the dosing sequence of the composition is calibrated to make optimal use of the relative equilibrium rates of the various chemical reactions. Each of the chemical reactions occurs at different rates and as a result CI species are constantly g back and forth between molecules and have different bilities at different times. In at least one embodiment the reagents required for the lower occurring reactions are added to the composition first and are allowed to react somewhat or tely before the reagents required for the faster ons are added. This avoids the faster reactions competing with the slower reactions. In at least one ment the reagents required to allow the chlorosulfamate species to react with the amine to form chloramine and ammonia is only added to the composition after chloroamine has been partially or completely formed.

In at least one embodiment the composition is diluted to produce a more mild (and less violent, reactive, or destructive) biocide effect. In at least one ment the methods of diluting biocides disclosed in US Patents 6,132,628 and 7,067,063 are employed. In at least one embodiment the ition is diluted so the species exists within the range of 100 ppm to 150,000 pp .

While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present sure is an ification of the background and principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. A l patents, patent applications, scientific papers, books, and any other referenced materials mentioned re herein, are incorporated by reference in their entirety. Furthermore, the invention encompasses any possible combination of some or all of the various embodiments described herein and incorporated herein.

The above disclosure is intended to be rative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term "comprising" means "including, but not limited to". Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also ed to be encompassed by the claims.

All ranges and parameters sed herein are understood to ass any and all subranges subsumed therein, and every number between the endpoints. For example, a stated range of " 1 to 10" should be considered to include any and all subranges between (and inclusive of) the m value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, (e.g. 1 to 6.1), and ending with a maximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 contained within the range.

This completes the description of the preferred and alternate embodiments of the invention. Those d in the art may ize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.

Claims

Claims (17)

What is claimed is:

1. A method of preventing the growth of microorganisms in a process water stream, the method including the step of: introducing a composition into the process water stream, the composition comprising: a halogen source, a halogen stabilizer containing a mixture of a sulfur g species with urea and/or ammonium sulfate at any ratio, and optionally an alkali, and wherein the sulfur bearing species includes sulfamic acid or its salt lent and the molar ratio of sulfamic acid to halogen atoms in the halogen source is more than 2 :1.

2. The method of claim 1 in which the sulfur bearing species further comprises a en stabilizer.

3. The method of claim 1 in which the nitrogen stabilizer is one item selected from the group consisting of ammonium sulfate, sodium sulfamate, and any combination f.

4. The method of claim 1 in which the molar ratio of halogen to all of the sulfur in the sulfur bearing species is more than 2:1.

5. The method of claim 1 in which the alkali is sodium hydroxide.

6. The method of claim 1 in which the halogen is chlorine, sodium hypochlorite, 1,3,5- Trichloroisocyanuric acid (TCCA), l-bromochloro-5,5-dimethyl-2,4-imidazolidedione (BCDMH) and l,3-dichloro-5,5-dimethyl-2,4-imidazolidedione (DCDMH).

7. The method of claim 1 further sing the steps of first adding to the sulfamic acid an alkali and then the adding urea and/or sodium e.

8. The method of claim 1 in which the process water stream is so rich in food for microorgasnisms that a single halogen t biocide is not effective at exterminating the microorganisms population but the composition is.

9. The method of claim 1 in which the s water stream is one selected from the list consisting of a cooling tower water stream, and papermaking process water stream.

10. The method of claim 2 in which the ratio of sulfamic acid or its salt to nitrogen stabilizer is optimized at any ratio between the more important concern of biocidal efficacy and impact on al ve present in the process water .

11. The method of claim 2 in which the ratio of sulfamic acid or its salt to nitrogen stabilizer is optimized at any ratio between the more important concern of biocidal efficacy and corrosion on equipment present in the s water stream.

12. The method of claim 1 in which the composition when used in a papermaking process does not reduce the effectiveness of OBA and DYE additives on paper made from that process.

13. The method of claim 1 in which the salt is sodium sulfamate.

14. The method of claim 1 in which the sulfamic acid or sulfamate is added to the composition before the ammonium salts are added.

15. The method of claim 1 in which the ammonium salts are added to the halogens before the sulfamic acid o sulfamate is added to the composition.

16. The method of claim 1 further comprising the step of adding ammonium salts or urea and sulfamic acid to the halogen.

17. The method of claim 1 in which the pH of the composition is adjusted to remain in the range of 4-1 1, more preferred 7-9.