Compositions with reduced salt concentrations for producing biocides

Abstract

A composition for producing a biocide is provided. The composition includes an ammonium salt, aqueous ammonia, and sodium bicarbonate. The composition can be mixed with a hypochlorite oxidizing agent to form the biocide. Previously known compositions included only an ammonium salt and, optionally, a base. The composition of the present invention is more economically favorable and has a more optimal pH than previously known compositions that include an ammonium salt of a strong acid (hydrobromic acid, hydrochloric acid, or sulfuric acid) or that include ammonium carbamate and sodium hydroxide. The preparation of the biocide can be monitored using a control parameter. A new control parameter, the ORP / pH ratio, is introduced.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) See U.S. Provisional Patent Application No. 63 / 398,558, filed August 17, 2022, entitled "METHOD FOR PRODUCING A BIOCIDE WITH LOW SALT CONTENT," the disclosure of which is incorporated herein by reference, the priority of which is hereby claimed under 37 CFR 1.78(a)(4) and (5)(i).

[0002] U.S. Patent Application No. 07 / 892,533 (filed June 1, 1992, entitled "PROCESS AND COMPOSITIONS FOR THE DISINFECTION OF WATERS"), U.S. Patent Application No. 08 / 809,346 (filed January 27, 1998, entitled "METHOD AND APPARATUS FOR TREATING LIQUIDS TO INHIBIT GROWTH OF LIVING ORGANISMS"), U.S. Patent Application No. 10 / 586,349 (filed July 14, 2006, entitled "BIOCIDES AND APPARATUS"), U.S. Patent Application No. 14 / 765,335 (filed August 1, 2015, entitled "METHOD FOR CONTROLLING THE PRODUCTION OF A No. 17 / 621,014 (filed December 20, 2021, entitled "METHOD FOR PRODUCING A BIOCIDE"), and U.S. Patent Application No. 17 / 619,851 (filed December 16, 2021, entitled "PROCESS FOR PRODUCING A SOLUTION OF AMMONIUM CARBAMATE"), the disclosures of which are incorporated herein by reference.

[0003] The present invention relates to compositions for producing biocides having reduced salt concentrations compared to previously known biocide-forming compositions. [Background technology]

[0004] Various compositions and techniques are known for producing chloramines from ammonium salts for use as biocides. Summary of the Invention

[0005] The present invention seeks to provide compositions useful in producing biocides.

[0006] Therefore, according to a preferred embodiment of the present invention, there is provided a composition for preparing a biocide, the composition comprising an ammonium salt comprising ammonium and an anion, aqueous ammonia, and sodium bicarbonate, wherein the total molar amount of ammonia and ammonium in the composition exceeds an equimolar amount of the anion in the composition by at least 10%, and the equimolar amount of the anion is the molar amount of the anion multiplied by its valence.

[0007] According to a preferred embodiment of the present invention, the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium bromide, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium phosphate, ammonium sulfamate, and ammonium sulfate. Preferably, the ammonium salt is selected from the group consisting of ammonium bromide, ammonium carbamate, ammonium chloride, and ammonium sulfate. Most preferably, the ammonium salt is ammonium bromide or ammonium carbamate.

[0008] According to another preferred embodiment of the present invention, the composition is an aqueous solution containing an ammonium salt at a concentration ranging from about 4 w / w% to about 36 w / w%, preferably at a concentration ranging from about 5 w / w% to about 27 w / w%.

[0009] According to different preferred embodiments of the present invention, the molar ratio of ammonium salt to aqueous ammonia is in the range of about 1:10 to about 10:1, more preferably in the range of about 1:3 to about 3:1. Preferred embodiments of the present invention include those in which the molar ratio of ammonium salt to aqueous ammonia is about 1:3, about 1:2, about 1:1, about 2:1, or about 3:1.

[0010] According to a preferred embodiment of the present invention, the concentration of aqueous ammonia is in the range of about 1 w / w% to about 21 w / w%, preferably in the range of about 2 w / w% to about 7 w / w%, and the concentration of sodium bicarbonate is preferably in the range of about 0.2 w / v% to about 10 w / v%, more preferably in the range of about 1 w / v% to about 5 w / v%, and most preferably about 2.7 w / v%.

[0011] According to one preferred embodiment of the invention, the molar amount of ammonia / ammonium exceeds the equimolar amount of anion by at least 20%. In another preferred embodiment, the molar amount of ammonia / ammonium exceeds the equimolar amount of anion by at least 25%. Further preferred embodiments include those in which the molar amount of ammonia / ammonium exceeds the equimolar amount of anion by at least 33%, at least 50%, at least 100%, at least 200%, or at least 300%.

[0012] Also in accordance with a preferred embodiment of the present invention, there is provided a method of making a biocide, the method comprising: providing a solution of hypochlorite oxidizing agent; providing a composition comprising an ammonium salt comprising ammonium and an anion, aqueous ammonia, and sodium bicarbonate, wherein the total molar amount of ammonia and ammonium in the composition exceeds an equimolar amount of the anion in the composition by at least 10%, the equimolar amount of the anion being the molar amount of the anion multiplied by its valence; and mixing the solution of hypochlorite oxidizing agent with the composition.

[0013] According to a preferred embodiment of the present invention, the hypochlorite oxidizing agent is sodium hypochlorite. Preferably, the hypochlorite oxidizing agent solution has a concentration in the range of about 1000 to about 20,000 ppm, more preferably in the range of about 3000 to about 10,000 ppm, and most preferably in the range of about 3500 to about 7000 ppm.

[0014] Preferably, the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium bromide, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium phosphate, ammonium sulfamate, and ammonium sulfate. More preferably, the ammonium salt is selected from the group consisting of ammonium bromide, ammonium carbamate, ammonium chloride, and ammonium sulfate. Most preferably, the ammonium salt is selected from the group consisting of ammonium bromide and ammonium carbamate.

[0015] According to a preferred embodiment of the present invention, the composition is prepared by combining an ammonium salt stock solution, an aqueous ammonia stock solution, and sodium bicarbonate to form a mixture and diluting the mixture with water or a solution of a hypochlorite oxidizing agent. The ammonium salt stock solution preferably has a concentration in the range of about 15% to about 50% w / w, more preferably about 20% to about 35% w / w.

[0016] Preferably, the aqueous ammonia stock solution has a concentration ranging from about 4 w / w% to about 28 w / w%, more preferably about 8.33 w / w%. The ammonium salt stock solution and the aqueous ammonia stock solution are preferably equimolar. Preferably, the molar ratio of ammonium salt to aqueous ammonia in the mixture ranges from about 1:10 to about 10:1, more preferably from about 1:3 to about 3:1.

[0017] According to a preferred embodiment of the present invention, the concentration of sodium bicarbonate in the mixture is in the range of about 0.2 w / v% to about 10 w / v%, more preferably in the range of about 1 w / v% to about 5 w / v%. Preferably, the method further comprises monitoring a control parameter during mixing. The control parameter is preferably selected from the group consisting of pH, oxidation-reduction potential (ORP), conductivity, dissolved oxygen saturation, and ORP / pH ratio. In a preferred embodiment, the control parameter is the ORP / pH ratio.

[0018] According to another preferred embodiment, the control parameter is conductivity. Preferably, mixing includes adding a solution of hypochlorite oxidizing agent to the composition and stopping the addition of the solution of hypochlorite oxidizing agent when the conductivity reaches a relative maximum. Preferably, the conductivity reaches a relative minimum before reaching a relative maximum. In a preferred embodiment, the pH of the biocide remains below 12.5. DETAILED DESCRIPTION OF THE INVENTION

[0019] As described in published European Patent Publication No. 0517102, the contents of which are incorporated herein by reference, biological fouling of circulating water is a well-known problem caused by algae, fungi, bacteria, and other simple life forms found in circulating water. This patent describes controlling biological fouling in high chlorine demand water by mixing two components, one an oxidizing agent and the other an ammonium salt, and adding this mixture substantially immediately to the aqueous system to be treated. This produces a biocidal active ingredient, as described therein. Numerous examples of oxidizing agents and ammonium salts are described in the patent publication.

[0020] However, a problem encountered with this method of treating liquids to inhibit biological growth is that concentrated biocidal active ingredients are highly chemically unstable and decompose rapidly upon formation, resulting in a rapid drop in pH. This is particularly true for biocidal active ingredients derived from ammonium bromide, where decomposition leads to the undesirable formation of HOBr and other decomposition by-products. Therefore, when conventional metering pumps and mixers are used, the formed biocidal active ingredient rapidly decomposes and loses its efficacy. Furthermore, while the pH range of such concentrated active biocides is theoretically 9.5 to 11.0, in practice, the pH can be as low as 8.0 due to rapid decomposition. Furthermore, to slow the rate of decomposition, an excess of ammonium salt was added.

[0021] U.S. Patent No. 5,976,386, the contents of which are incorporated herein by reference, discloses a method and apparatus for producing a biocide that allows for maintaining a constant oxidizer / amine source ratio, thereby avoiding the need to use excess amine source to stabilize the reaction product and maintain a reproducible product that is largely free of decomposition products. The novel method described therein involves producing efficient in situ dilutions of both the oxidizer and the amine source, and simultaneously metering the two dilutions into a conduit and continuously mixing them therein according to a predetermined ratio to produce the biocidal active ingredient. The predetermined ratio was an amine to oxidizer ratio of at least 1:1.

[0022] As previously described in U.S. Patent No. 5,976,386, careful control of biocide formation is necessary. Biocide production processes use a multiple-feed point system, requiring separate control for each feed line because different pumps respond differently to pressure changes and pump feed rates depend on water flow pressure. For any on-site process, online control is required to ensure proper product production with high yield and minimal by-products. Furthermore, the above-referenced patents disclose that equimolar amounts of ammonium and hypochlorite are required for optimal performance. The components used to make biocides, such as sodium hypochlorite and ammonium carbamate, as disclosed in U.S. Patent No. 7,837,883, the contents of which are incorporated herein by reference, are unstable chemicals that decompose over time during use. As a result, operating a feed unit under a predetermined, constant feed rate of the two reagents produces variable products. Furthermore, other parameters, such as water temperature, excessively high pH, high concentrations of the generated biocide, and water quality, can accelerate biocide degradation. This can be a serious problem if the alkalinity of the NaOCl is too high. It has been demonstrated, particularly for biocides prepared from ammonium carbamate, that producing the biocide in the presence of excess free ammonia impairs the efficacy of the biocide.

[0023] U.S. Patent No. 5,976,386 discloses the use of pH as an endpoint indicator for the reaction of ammonium salts with sodium hypochlorite. Adding hypochlorite to an ammonium salt solution increases the pH. However, after reaching the equimolar point and all of the ammonium salt has reacted, the hypochlorite begins to decompose the biocidal MCA to form inorganic acid, which lowers the pH. Therefore, pH can be used as an endpoint indicator. However, it was found that pH is only an accurate indicator at relatively low pH values. Because biocide production is carried out at a relatively high pH, other indicators were needed.

[0024] U.S. Patent No. 9,801,384, the entire contents of which are incorporated herein by reference, discloses additional parameters that can be used to indicate the endpoint of the reaction between an ammonium salt and a hypochlorite oxidizing agent. Specifically, oxidation-reduction potential (ORP), conductivity, and inductivity were all shown to have relative minimum values at the endpoint. Dissolved oxygen was shown to have a constant value during the reaction and rapidly decrease at the endpoint. These parameters were shown to be effective in identifying the endpoint of the reaction. If the endpoint was overlooked and excess hypochlorite was added, the result was assumed to be biocide decomposition, loss of efficacy, and the production of undesirable decomposition by-products.

[0025] Even when the correct amount of ammonium salt is used, this salt is a relatively expensive component. Ammonium salts are significantly more expensive than ammonia, which is available as an aqueous solution, also known as ammonium hydroxide. It is believed that it is the ammonium moiety of the ammonium salt that reacts with hypochlorite to form the monochloramine biocide, and the counterion to ammonium plays no significant role in biocidal activity. However, biocides made from aqueous ammonia and hypochlorite have been found to have lower biocidal activity than those made from ammonium salts. The use of aqueous ammonia to produce chloramine is also known to be used in large-scale freshwater disinfection plants. However, it presents logistical problems in industrial applications due to the physical properties of aqueous ammonia. Because the pH of aqueous ammonia is so high, the monochloramine produced decomposes during production. Furthermore, the continuous loss of ammonia from aqueous ammonia makes it an impractical option for most industrial applications. It would be economically advantageous to be able to replace at least a portion of ammonium salts, such as ammonium bromide, ammonium carbamate, ammonium sulfate, or ammonium chloride, with aqueous ammonia without reducing the activity of the biocide produced therewith. Reducing the counterion content may also alleviate other problems, such as chloride corrosion potential for biocides made from ammonium chloride, and sulfate-reducing bacterial growth for biocides made from ammonium sulfate.

[0026] The quality of the sodium hypochlorite solution presents an additional problem when preparing monochloramine biocides. Sodium hypochlorite is formed from the reaction of chlorine gas with sodium hydroxide. The resulting solution contains alkalinity in the form of residual sodium hydroxide. The alkalinity of sodium hypochlorite solutions is typically about 0.7–0.8%, but it can vary significantly, from very low (0.1–0.3%) to very high (up to 3%). Low alkalinity inhibits the formation of monochloramine from ammonium salts derived from strong acids, such as ammonium bromide, ammonium chloride, and ammonium sulfate. If the alkalinity is too high, it can affect all ammonium salts, but particularly those derived from weak acids, such as ammonium carbamate and ammonium carbonate. Replacing some of the salt with aqueous ammonia increases the ammonia salt's resistance to the alkalinity of the hypochlorite solution, significantly improving the efficacy of the biocide in practice.

[0027] According to a first embodiment of the present invention, there is provided a composition useful for producing a biocide, the composition comprising an ammonium salt, aqueous ammonia, and sodium bicarbonate.

[0028] The ammonium salt is preferably selected from ammonium bicarbonate, ammonium bromide, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium phosphate, ammonium sulfamate, and ammonium sulfate. More preferably, the ammonium salt is selected from ammonium bromide, ammonium carbamate, ammonium chloride, and ammonium sulfate. Even more preferably, the ammonium salt is selected from ammonium bromide and ammonium carbamate. The ammonium salt is provided as an aqueous solution having a concentration of preferably about 15 to 50 w / w %, more preferably about 20 to 35 w / w %.

[0029] The aqueous ammonia is preferably provided as an aqueous solution with a concentration of about 4 to 28 w / w%, more preferably about 8.33 w / w%. The ammonium salt and aqueous ammonia are mixed in a molar ratio of about 1:10 to 10:1, more preferably about 1:3 to 3:1, more preferably about 1:3, 1:2, 1:1, 2:1, or 3:1. The aqueous ammonia solution and the ammonium salt solution are preferably equimolar, so that the molar ratio is equal to the volume ratio.

[0030] Due to the addition of aqueous ammonia, the total molar amount of ammonia and ammonium is in excess relative to the molar amount of the anion of the ammonium salt. When the anion is a polyvalent ion, such as a divalent sulfate or trivalent phosphate, the molar amount of ammonium from the ammonium salt is two or three times the molar amount of the anion. Thus, the excess of ammonia / ammonium relative to an equimolar amount of anion is measured, where the equimolar amount is equal to the molar amount of anion multiplied by the valency of the anion. In one embodiment, the molar amount of ammonia / ammonium is about 10% in excess relative to an equimolar amount of the anion of the ammonium salt. In other embodiments, the molar amount of ammonia / ammonium is about 20%, about 25%, about 33%, about 50%, about 100%, about 200%, about 300%, or about 1000% in excess relative to an equimolar amount of the anion of the ammonium salt.

[0031] Sodium bicarbonate is preferably added as a solid to the mixture of ammonium salt and aqueous ammonia. The concentration of sodium bicarbonate in the composition is preferably 0.2 to 10 w / v%, more preferably about 1 to 5 w / v%, and most preferably about 2 w / v% or about 2.7 w / v%.

[0032] The term "about" is used throughout this specification when preceding a numerical value to refer to a range of 10% above or below that value.

[0033] The compositions of the present invention are useful for preparing halogenated amine biocides. The biocides are preferably prepared by mixing an ammonium salt composition with a hypochlorite oxidizing agent. Preferably, the reaction resulting from the mixing produces monochloramine.

[0034] In one embodiment, the biocide is produced by a batch process. The batch process involves adding a pre-diluted solution of hypochlorite oxidizing agent to the composition of the present invention in small increments while mixing. A control parameter can be monitored during mixing. In some embodiments, the control parameter is pH, where a pH maximum indicates that all of the ammonia and ammonium have reacted, and further addition of hypochlorite causes the biocide to decompose. In other embodiments, the control parameter is oxidation-reduction potential (ORP) or conductivity, where a minimum in ORP or conductivity indicates that all of the ammonia and ammonium have reacted. If the composition contains ammonium carbamate and is first diluted with sodium hypochlorite, the conductivity will reach a minimum and then a maximum before the monochloramine decomposes. In yet another embodiment, the control parameter is dissolved oxygen saturation, which remains approximately constant throughout the reaction between ammonia / ammonium and hypochlorite and begins to decrease when the ammonia / ammonium is depleted.

[0035] In the present invention, the composition that reacts with hypochlorite contains the mixture of ammonium salt derived from strong acid such as ammonium bromide, ammonium chloride or ammonium sulfate and aqueous ammonia, and the starting pH of the composition is higher than the starting pH of the composition that does not contain aqueous ammonia.Therefore, the change in pH, and therefore the maximum pH value, may be difficult to observe.It should be noted that the composition that contains ammonium carbamate and aqueous ammonia has a higher pH in solution than the solution of ammonium carbamate alone, but the pH of the composition is lower than the pH of the ammonium carbamate formulation that contains 8% sodium hydroxide currently on the market.

[0036] Furthermore, the initial conductivity of the compositions of the present invention is lower than that of compositions without aqueous ammonia. Therefore, as the ammonia content in the composition increases, it may become difficult to observe the minimum conductivity value. While the ORP exhibits a minimum value, this minimum is much less clear than the minimum value for solutions without aqueous ammonia. In such situations, the ORP / pH ratio can be used to more easily observe the endpoint. Because ORP generally decreases as pH increases, the ORP / pH ratio has a more observable minimum and can be used as a control parameter. Additionally, because ORP takes longer to achieve a stable reading than pH, using the ratio improves accuracy, especially when biocides are manufactured in a continuous process. Preferably, the biocide is manufactured on-site and used immediately after production.

[0037] In an alternative embodiment, the biocide is produced in a continuous process. In a continuous process, a solution of hypochlorite and a solution of the composition of the present invention are continuously mixed in a mixer, and a control parameter is monitored online in the mixer or in a conduit downstream from the mixer, or measured in a separate sample taken from the mixer. The flow rate of one solution is kept constant, and the flow rate of the other solution is changed to change the ammonia / ammonium to hypochlorite ratio until the control parameter indicates that the ideal ratio is achieved. The biocide produced in a continuous process is preferably applied to the culture medium as it is produced.

[0038] The hypochlorite oxidizing agent can be any hypochlorite oxidizing agent, such as an alkali metal or alkaline earth metal hypochlorite salt. Preferably, the hypochlorite salt is sodium hypochlorite, potassium hypochlorite, or calcium hypochlorite. Most preferably, the hypochlorite salt is sodium hypochlorite.

[0039] The hypochlorite solution is preferably prepared by mixing a concentrated stock solution of hypochlorite with water to form a dilute hypochlorite solution. The concentration of the dilute hypochlorite solution is preferably about 1000 to about 20,000 ppm. More preferably, the concentration of the hypochlorite solution is about 3000 to about 10,000 ppm. Most preferably, the concentration of the hypochlorite solution is about 3500 to about 7000 ppm. The hypochlorite solution is preferably prepared by diluting an about 8 to 18 wt. % stock solution with water immediately before use. When the biocide is formed in a continuous process, the dilute hypochlorite solution is preferably prepared online as needed.

[0040] The compositions of the present invention are preferably diluted before mixing with hypochlorite. In one embodiment, the composition is diluted with water to an ammonia / ammonium concentration of about 1,000 to about 50,000 ppm, more preferably about 3,500 to about 10,000 ppm. Most preferably, the composition is diluted so that equal volumes of the ammonia / ammonium composition and the hypochlorite dilution result in an equimolar mixture of ammonia / ammonium and hypochlorite. In an alternative embodiment, the composition is diluted with a diluted hypochlorite solution. This embodiment is particularly suitable for compositions containing ammonium carbamate. However, unlike previously known ammonium carbamate compositions, the present compositions containing ammonium carbamate and aqueous ammonia can be diluted with water. Preferably, the diluted composition is prepared immediately before use. If the biocide is formed in a continuous process, the diluted composition is preferably prepared online as needed. [Example]

[0041] General method A stock solution of sodium hypochlorite (approximately 12.5% as Cl2) was diluted in DI water to a concentration of approximately 6000 to approximately 10,000 ppm (as Cl2). A stock solution of approximately 5 to 10 w / w% ammonia water was prepared from a commercially available solution of 20 to 28 w / w%. An ammonium salt composition was prepared by mixing a stock solution of ammonium salt (20 to 35%) with a stock solution of ammonia water. A volume of the composition was added to 50 mL of deionized (DI) water to achieve an equimolar concentration of approximately 5000 to approximately 10,000 ppm hypochlorite (as Cl2). When the ammonium salt is ammonium carbamate, 2.3 mL of the ammonium salt composition may be diluted to 30 mL of diluted hypochlorite solution.

[0042] The diluted hypochlorite solution was titrated into the ammonia salt solution while measuring pH, ORP, conductivity, and dissolved oxygen. In each example, the volume of hypochlorite found to be the exact volume of the sample without aqueous ammonia was used for all samples. When forming a biocide by titrating hypochlorite into ammonia / ammonium, the biocide concentration is equal to the concentration of added hypochlorite and varies throughout the titration depending on the volume of added hypochlorite. Therefore, using the same volume of hypochlorite for each sample ensures a consistent concentration of biocide. This is confirmed by a consistent chlorine residual at time 0. The lack of biocide degradation was confirmed by dissolved oxygen measurements. The biocide was then diluted 10-fold and then further diluted to its final concentration.

[0043] E. coli and Bacillus were grown in LB medium, washed with phosphate buffered saline (PBS), and diluted to approximately 2 × 10 7 ~2×10 8The samples were concentrated to cfu / mL. In some tests, glucose (approximately 5%) was added to the washed samples to ensure removal of residual free chlorine in case the biocide was partially degraded, and to simulate real-life conditions where microorganisms grow in the presence of food despite the addition of biocides. Mixed microbial populations grown from wastewater samples were also tested.

[0044] Aliquots of diluted biocide were added to the bacteria to a final concentration of 0.4-1.5 ppm (as Cl2). Residual chlorine was measured in the DI water at the beginning of each test and in the test solution approximately 60 minutes later after plating the organisms. Samples were shaken at 25°C for 60 minutes and then inactivated with 50 μL of sodium thiosulfate (2%). Samples were serially diluted 10-fold approximately five or six times, plated on LB agar, and incubated at 37°C for 48 hours.

[0045] Example 1 Stock solutions 1-5 were prepared by mixing different volumes of ammonium bromide (35 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 1. The pH of each solution was measured. Biocides were prepared as described in the general methods above and applied to the bacillus samples at a final concentration of 0.5 ppm (as Cl2). The chlorine residuals and viable counts after biocide treatment are shown in Table 2.

[0046] The results show that as the proportion of ammonium bromide decreases, the efficacy of the biocide also decreases. The highest efficacy was found with pure ammonium bromide without aqueous ammonia, despite the low chlorine residual.

[0047] [Table 1]

[0048] [Table 2]

[0049] Example 2 Stock solutions 1-4 were prepared by mixing different volumes of sodium bromide (36.8 w / w% solution) with a fixed volume of aqueous ammonia (8.33 w / w% solution) and making up to the fixed volume with water, as shown in Table 3. The pH of each solution was measured. Biocides were prepared as described in the general methods above and fed to the bacillus samples at a final concentration of 1.0 ppm (as Cl2). The chlorine residuals and viable counts after biocide treatment are shown in Table 4.

[0050] [Table 3]

[0051] [Table 4]

[0052] The above results show that as the bromide percentage decreases, the biocide efficacy also decreases. This example demonstrates that the decrease in efficacy shown in Example 1 is not related to an increase in the pH of the formulation.

[0053] Example 3 Stock solutions 1-5 were prepared by mixing different volumes of ammonium bromide (35 w / w% solution) and ammonium chloride (19.1 w / w% solution), as shown in Table 5. The pH of each solution was measured. Biocides were prepared as described in the general methods above and applied to the bacillus samples at a final concentration of 1.0 ppm (as Cl2). The chlorine residuals and viable counts after biocide treatment are shown in Table 6.

[0054] The results show that as the percentage of ammonium bromide decreases, the efficacy of the biocide also decreases. Since all samples had a similar low pH, the decrease in activity cannot be attributed to a change in pH.

[0055] [Table 5]

[0056] [Table 6]

[0057] Example 4 Stock solutions 1-4 were prepared by mixing different volumes of ammonium carbamate (20 w / w% solution) and aqueous ammonia (4.8 w / w% solution), as shown in Table 7. The pH and conductivity of each solution were measured. Biocide was prepared as described in the general method above and added to the bacillus samples at a final concentration of 0.8 ppm (as Cl2). The bacillus samples contained 5% glucose. The chlorine residual and viable count after biocide treatment are shown in Table 8.

[0058] [Table 7]

[0059] [Table 8]

[0060] The above results show that as the proportion of ammonium carbamate decreases, the efficacy of the biocide also decreases. In the presence of glucose, the chlorine demand is significantly higher. There is no direct interaction between the biocide and glucose. The high demand is due to the strong microbial activity in the presence of glucose. Therefore, glucose makes the culture more resistant to the biocide and has a higher similarity to real life activity.

[0061] Example 5 Stock solutions 1-5 were prepared by mixing different volumes of ammonium bromide (35 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 9. Sodium bicarbonate was added to each stock solution at a concentration of 2.7 w / v%. The pH of each solution was measured. Biocides were prepared as described in the general method above and fed to the bacillus samples at a final concentration of 1.0 ppm (as Cl2). The bacillus samples contained 5% glucose. The chlorine residuals and viable counts after biocide treatment are shown in Table 10.

[0062] [Table 9]

[0063] [Table 10]

[0064] The above results show that a small amount of sodium bicarbonate added to the ammonium salt mitigates the effect of bromide removal demonstrated in Example 1 above.

[0065] Example 6 Stock solutions 1-6 were prepared by mixing different volumes of ammonium bromide (35 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 11. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7%. The pH of each solution was measured. Biocides were prepared as described in the general method above and fed to E. coli samples at a final concentration of 1.0 ppm (as Cl2). E. coli samples contained 5% glucose. The chlorine residuals and viable counts after biocide treatment are shown in Table 12.

[0066] [Table 11]

[0067] [Table 12]

[0068] The above results show that a small amount of sodium bicarbonate added to the ammonium salt mitigates the bromide removal effect demonstrated above in Example 1. The sample containing a 1:1 mixture of ammonium bromide and aqueous ammonia performed better than the pure ammonium bromide sample without sodium bicarbonate.

[0069] Example 7 Stock solutions 1-6 were prepared by mixing different amounts of sodium bicarbonate into an equal volume mixture of ammonium bromide (35 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 13. The pH and conductivity of each solution were measured. Biocides were prepared as described in the general method above and fed to E. coli samples at a final concentration of 1.0 ppm (as Cl2). The E. coli samples contained 5% glucose. The chlorine residuals and viable counts after biocide treatment are shown in Table 14.

[0070] [Table 13]

[0071] [Table 14]

[0072] As the buffering effect of sodium bicarbonate increases, the pH of the mixture decreases slightly, but the overall effect on the pH of the ammonium bromide / aqueous ammonia mixture is minimal. There is also no substantial effect on the conductivity of the formulated mixture. The increase in efficacy is related to the concentration of sodium bicarbonate, with best results being achieved at a feed rate of 2 w / v% sodium bicarbonate in the ammonium bromide / aqueous ammonia composition. At higher concentrations of sodium bicarbonate, efficacy decreased.

[0073] Example 8 Stock solutions 1-5 were prepared by mixing different volumes of ammonium chloride (19.1 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 15. Sodium bicarbonate was added to solutions 2-5 at a concentration of 2.7 w / v%. The pH and conductivity of each solution were measured. Biocides were prepared as described in the general method above and added to a sample of a mixture of microorganisms (MOs) isolated from domestic wastewater at a final concentration of 1.5 ppm (as Cl2). The chlorine residuals and viable counts after biocide treatment are shown in Table 16.

[0074] The results show that a small amount of sodium bicarbonate added to the ammonium salt improves biocidal activity. Samples containing a 1:1 mixture of ammonium chloride and aqueous ammonia performed similarly to samples of pure ammonium chloride without sodium bicarbonate, and samples containing a 3:1 mixture of ammonium chloride and aqueous ammonia performed even better.

[0075] [Table 15]

[0076] [Table 16]

[0077] Example 9 Stock solutions 1-6 were prepared by mixing different volumes of ammonium carbamate (20 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 17. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7 w / v%. The pH and conductivity of each solution were measured. Biocides were prepared as described in the general method above and added to a sample of a mixture of microorganisms (MOs) isolated from domestic wastewater at a final concentration of 1.5 ppm (as Cl2). The chlorine residual and viable count after biocide treatment are shown in Table 18.

[0078] The results show that a small amount of sodium bicarbonate added to the ammonium salt mitigates the carbamate removal effect demonstrated above in Example 4. The sample containing a 1:1 mixture of ammonium carbamate and ammonium hydroxide performed best.

[0079] [Table 17]

[0080] [Table 18]

[0081] Example 10 Stock solutions 1-6 were prepared by mixing different amounts of sodium bicarbonate with aqueous ammonia (8.33 w / w% solution), as shown in Table 19. The pH and conductivity of each solution were measured. Biocide was prepared as described in the general method above and fed to the mixed culture samples at a final concentration of 1.0 ppm (as Cl2). The mixed culture samples contained 5% glucose. The chlorine residual and viable count after biocide treatment are shown in Table 20.

[0082] While this option is not practical for on-site application in industrial applications due to the properties of aqueous ammonia, it is an interesting theoretical example. The effect of increasing the concentration of sodium bicarbonate on the pH and conductivity of the formulation is clear. While aqueous ammonia alone exhibits modest overall efficacy, the effect of adding sodium bicarbonate is clear and follows a similar trend to that observed with ammonium salts.

[0083] [Table 19]

[0084] [Table 20]

[0085] Example 11 Stock solutions 1-5 were prepared by mixing different volumes of ammonium carbamate (20 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 21. 2.3 mL of each sample was diluted into 30 mL of 5000 ppm (as Cl2) sodium hypochlorite solution. Additional sodium hypochlorite was added while measuring pH, conductivity, and ORP. This resulted in an error in the measurement of solution 1.

[0086] [Table 21]

[0087] Table 22 shows the results of the conductivity measurements. The conductivity is expected to have a minimum value followed by a maximum value. The maximum conductivity for each solution is in bold. As the amount of aqueous ammonia increases, the change in conductivity becomes smaller and the maximum occurs sooner. Therefore, conductivity becomes an unviable control parameter.

[0088] [Table 22]

[0089] Table 23 shows the results of the pH measurements. The maximum pH value for each solution is in bold. A maximum was observed for each solution, but as the amount of aqueous ammonia increased, the pH maximum became less distinct and more difficult to observe, making it an impractical control parameter. Furthermore, it can be seen that no maximum was observed at a given hypochlorite dosage.

[0090] [Table 23]

[0091] Table 24 shows the results of the ORP measurements. The minimum ORP value for each solution is in bold. A minimum was observed for each solution, but as the amount of aqueous ammonia increased, the ORP minimum became less clear and more difficult to observe. Furthermore, accurately measuring ORP requires some equilibration time after adding hypochlorite to the ammonium salt formulation. In the laboratory setting described herein, such equilibration time is available. However, in the field, when using a continuous process to manufacture biocides, such as those described in U.S. Patent No. 9,801,384, there is no time for equilibration. Therefore, it can be difficult to observe slight differences in ORP for biocides made using aqueous ammonia.

[0092] [Table 24]

[0093] Table 25 shows a new parameter, the ORP / pH ratio. This parameter is consistent across all samples and has a minimum value that was found to be observable. Therefore, it is a useful parameter for controlling biocide production even under conditions where pH or ORP alone cannot be used. Generally, before the reaction endpoint, ORP decreases and pH increases, so using the ORP / pH ratio amplifies the changes in the individual parameters, making the endpoint easier to observe.

[0094] [Table 25]

[0095] Example 12 Stock solutions 1-6 were prepared by mixing different volumes of ammonium carbamate (20 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 26. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7 w / v%. A sample of each solution was diluted in 50 mL of DI water, and sodium hypochlorite was added while measuring pH, conductivity, and ORP. Conductivity was found not to be a useful parameter for control.

[0096] [Table 26]

[0097] Table 27 shows the results of the pH measurements. The maximum pH value for each solution is in bold. A maximum was observed for each solution, but as the amount of aqueous ammonia increased, the pH maximum became less distinct and more difficult to observe, making it an impractical control parameter. Furthermore, it can be seen that no maximum was observed at a given hypochlorite dosage.

[0098] [Table 27]

[0099] Table 28 shows the results of the ORP measurements. The minimum ORP value for each solution is in bold. A minimum was observed for each solution, but as the amount of aqueous ammonia increased, the ORP minimum became less distinct and more difficult to observe.

[0100] Table 29 shows a new parameter, the ORP / pH ratio. This parameter is consistent across all samples and has a minimum value that was found to be observable. Therefore, it is a useful parameter for controlling biocide production even under conditions where pH or ORP alone cannot be used. Generally, before the reaction endpoint, ORP decreases and pH increases, so using the ORP / pH ratio amplifies the change in each parameter, making the endpoint easier to observe.

[0101] A further important result to note is that when using previously known solutions of ammonium carbamate containing 8% NaOH, the biocide can only be prepared by diluting the carbamate solution in a dilute hypochlorite solution, whereas when using the compositions of the present invention, the biocide can also be prepared by diluting the composition in water.

[0102] [Table 28]

[0103] [Table 29]

[0104] Example 13 Stock solutions 1-6 were prepared by mixing different volumes of ammonium bromide (35 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 30. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7 w / v%. A sample of each solution was diluted in 50 mL of DI water, and sodium hypochlorite was added while measuring pH, conductivity, and ORP. Conductivity was found not to be a useful parameter for control.

[0105] [Table 30]

[0106] Table 31 shows the results of the pH measurements. The maximum pH value for each solution is in bold. A maximum was observed for each solution, but as the amount of aqueous ammonia increased, the pH maximum became less distinct and more difficult to observe, making it an unfeasible control parameter.

[0107] [Table 31]

[0108] Table 32 shows the results of the ORP measurements. The minimum ORP value for each solution is in bold. A minimum was observed for each solution, but as the amount of aqueous ammonia increased, the ORP minimum became less distinct and more difficult to observe.

[0109] [Table 32]

[0110] Table 33 shows a new parameter, the ORP / pH ratio. This parameter is consistent across all samples and has a minimum value that was found to be observable. Therefore, it is a useful parameter for controlling biocide production even under conditions where pH or ORP cannot be used alone. Because ORP generally decreases and pH increases before the reaction endpoint, using the ORP / pH ratio amplifies the changes in the individual parameters, making the endpoint easier to observe.

[0111] [Table 33]

[0112] Example 14 Stock solutions 1-6 were prepared by mixing different volumes of ammonium chloride (19.1 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 34. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7 w / v%. Samples of each solution were diluted in 50 mL of DI water, and sodium hypochlorite was added while measuring pH, conductivity, and ORP. Conductivity was found not to be a useful parameter for control.

[0113] [Table 34]

[0114] Table 35 shows the results of the pH measurements. The maximum pH value for each solution is in bold. A maximum was observed for each solution, but as the amount of aqueous ammonia increased, the pH maximum became less distinct and more difficult to observe, making it an unfeasible control parameter.

[0115] Table 36 shows the results of the ORP measurements. The minimum ORP value for each solution is in bold. A minimum was observed for each solution, but as the amount of aqueous ammonia increased, the ORP minimum became less distinct and more difficult to observe.

[0116] Table 37 shows a new parameter, the ORP / pH ratio. This parameter has a minimum value that was found to be consistent and observable across all samples. Therefore, it is a useful parameter for controlling biocide production even under conditions where pH or ORP cannot be used alone. Because ORP generally decreases and pH increases before the reaction endpoint, using the ORP / pH ratio amplifies the changes in the individual parameters, making the endpoint easier to observe.

[0117] [Table 35]

[0118] [Table 36]

[0119] [Table 37]

[0120] Example 15 Stock solutions 1-6 were prepared by mixing different volumes of ammonium carbamate (20 w / w% solution) and aqueous ammonia (8.33 w / w% solution), as shown in Table 38. Sodium bicarbonate was added to solutions 2-6 at a concentration of 2.7 w / v%. Comparative solution 0 was a formulation of 20 w / w% ammonium carbamate containing 8 w / w% NaOH. The pH and conductivity of each solution were measured. Biocides were prepared as described in the general method above and added to the E. coli samples at a final concentration of 0.5 ppm (as Cl2). The chlorine residuals and viable counts after biocide treatment are shown in Table 39.

[0121] [Table 38]

[0122] [Table 39]

[0123] These results indicate that the efficacy of the biocide formed from the composition containing ammonium carbamate, aqueous ammonia, and sodium bicarbonate is at least as good as the formulation containing ammonium carbamate and sodium hydroxide. The compositions of the present application are advantageous in that they have a lower pH compared to commercially available formulations, allowing for easier handling.

[0124] It is interesting to compare Solutions 1 and 2, which contain no aqueous ammonia and differ only in that Solution 2 contains sodium bicarbonate. Solution 2 performed better than Solution 1 at reducing E. coli. When supplied at a rate of 1 ppm (as Cl), Solution 1 had a microbial count of 1.10E+02, while no microorganisms were observed in samples treated with Solution 2. This indicates that sodium bicarbonate improves the activity of biocides formed from ammonium salts, even in the absence of aqueous ammonia.

[0125] To understand this effect, the control parameters for biocide formation were examined. For Solution 1, the pH maximum and ORP minimum were observed after the addition of 140 mL of sodium hypochlorite. For Solution 2, which contained sodium bicarbonate, the pH maximum and ORP minimum were observed after the addition of 150 mL of sodium hypochlorite. This indicates that for the bicarbonate-containing solution, more ammonia is available to react with hypochlorite, resulting in a higher concentration of biocide.

[0126] Example 16 The biocide was prepared by titrating low-alkalinity sodium hypochlorite into a solution of ammonium bromide (approximately 4500 ppm). The results in Table 40 below show that at low alkalinity, the biocide decomposes as it is produced, and the low pH makes it impossible to reach the equimolar point, as decomposition occurs rapidly even with excess ammonium bromide. The composition of the present invention alleviates this problem, as the pH of the composition is higher than the pH of the ammonium bromide solution.

[0127] [Table 40]

[0128] Example 17 A biocide was prepared by titrating a commercially available sample of highly alkaline sodium hypochlorite into a 19.5 wt% ammonium carbamate solution containing 8% sodium hydroxide, while measuring pH, ORP, and conductivity. The sodium hypochlorite titrant was formed by diluting 6.6 mL of the commercially available solution with 100 mL of DI water. As can be seen from Table 41, the ORP / pH ratio, which is expected to decrease with increasing pH, actually increased with increasing pH, indicating that the biocide was decomposing, even when the ammonium carbamate was in high excess relative to the sodium hypochlorite and the pH was very high. The conductivity, resulting from the excess alkalinity, was also very high, reaching a maximum conductivity before the actual reaction endpoint due to continued decomposition. The compositions of the present invention alleviate this problem because the pH of the compositions is lower than the pH of the ammonium carbamate solution containing 8% sodium hydroxide, and the conductivity is also lower.

[0129] [Table 41]

[0130] Example 18 To further demonstrate the benefits of the present invention over a solution of ammonium carbamate containing 8% sodium hydroxide, two solutions were prepared. Solution 1 contained 20% ammonium carbamate and 8% sodium hydroxide. Solution 2 contained 15% ammonium carbamate (w / w), 2.4% ammonia (w / w), and 2.5% sodium bicarbonate (w / v). 2.3 ml of each solution was diluted with 30 ml of sodium hypochlorite, and additional amounts of sodium hypochlorite were added while monitoring pH, conductivity, and ORP. The results for Solution 1 and Solution 2 are shown in Tables 42 and 43, respectively.

[0131] [Table 42]

[0132] [Table 43]

[0133] In Solution 1, the conductivity maximum occurred at 80 mL of hypochlorite, while in Solution 2, the conductivity maximum occurred at 130 mL of hypochlorite. The pH in the biocide made from Solution 1 was high, which apparently accelerated biocide decomposition. In the biocide made from Solution 2, the pH remained below 12.5, thus slowing biocide decomposition and allowing for the preparation of larger quantities of biocide from the same amount of ammonium carbamate. The composition containing ammonium carbamate, aqueous ammonia, and sodium bicarbonate eliminates the need for the addition of sodium hydroxide, previously thought to be necessary to stabilize ammonium carbamate, reducing the amount of ammonium carbamate required and resulting in a more stable biocide.

[0134] Those skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described above, but rather the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as modifications thereof which would occur to those skilled in the art upon reading the foregoing description and which are not in the prior art.

Claims

1. 1. A composition for preparing a biocide, said composition comprising: an ammonium salt containing ammonium and an anion; Ammonia water, sodium bicarbonate, the total molar amount of ammonia and ammonium in said composition exceeds the equimolar amount of said anion in said composition by at least 10%; wherein said equimolar amount of said anion is the molar amount of said anion multiplied by its valency.

2. 10. The composition of claim 1, wherein the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium bromide, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium phosphate, ammonium sulfamate, and ammonium sulfate.

3. 3. The composition of claim 1, wherein the ammonium salt is selected from the group consisting of ammonium bromide, ammonium carbamate, ammonium chloride, and ammonium sulfate.

4. The composition of any one of claims 1 to 3, wherein the ammonium salt is ammonium bromide.

5. The composition according to any one of claims 1 to 3, wherein the ammonium salt is ammonium carbamate.

6. The composition according to any one of claims 1 to 5, which is an aqueous solution comprising the ammonium salt at a concentration ranging from about 4 w / w% to about 36 w / w%.

7. The composition according to any one of claims 1 to 6, which is an aqueous solution comprising the ammonium salt at a concentration ranging from about 5% w / w to about 27% w / w.

8. The composition of any one of claims 1 to 7, wherein the molar ratio of the ammonium salt to the aqueous ammonia ranges from about 1:10 to about 10:

1.

9. The composition of any one of claims 1 to 8, wherein the molar ratio of the ammonium salt to the aqueous ammonia ranges from about 1:3 to about 3:

1.

10. 10. The composition of claim 1, wherein the molar ratio of the ammonium salt to the aqueous ammonia is about 1:

3.

11. 10. The composition of claim 1, wherein the molar ratio of the ammonium salt to the aqueous ammonia is about 1:

2.

12. 10. The composition of claim 1, wherein the molar ratio of the ammonium salt to the aqueous ammonia is about 1:

1.

13. 10. The composition of claim 1, wherein the molar ratio of the ammonium salt to the aqueous ammonia is about 2:

1.

14. 10. The composition of claim 1, wherein the molar ratio of the ammonium salt to the aqueous ammonia is about 3:

1.

15. The composition of any one of claims 1 to 14, wherein the concentration of the aqueous ammonia ranges from about 1 w / w % to about 21 w / w %.

16. The composition according to any one of claims 1 to 15, wherein the concentration of the aqueous ammonia ranges from about 2 w / w% to about 7 w / w%.

17. 17. The composition of any one of claims 1 to 16, wherein the concentration of sodium bicarbonate ranges from about 0.2% w / v to about 10% w / v.

18. 18. The composition of any one of claims 1 to 17, wherein the concentration of sodium bicarbonate ranges from about 1% w / v to about 5% w / v.

19. 19. The composition of any one of claims 1 to 18, wherein the concentration of sodium bicarbonate is about 2.7% w / v.

20. 20. The composition of any one of claims 1 to 19, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 20%.

21. 21. The composition of any one of claims 1 to 20, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 25%.

22. 22. The composition of any one of claims 1 to 21, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 33%.

23. 23. The composition of any one of claims 1 to 22, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 50%.

24. 24. The composition of any one of claims 1 to 23, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 100%.

25. 25. The composition of any one of claims 1 to 24, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 200%.

26. 26. The composition of any one of claims 1 to 25, wherein the molar amount of ammonia / ammonium exceeds the equimolar amount of the anion by at least 300%.

27. 1. A method for producing a biocide, comprising: providing a solution of hypochlorite oxidizer; Providing a composition, said composition comprising: an ammonium salt containing ammonium and an anion; Ammonia water, sodium bicarbonate, the total molar amount of ammonia and ammonium in said composition exceeds the equimolar amount of said anion in said composition by at least 10%; providing a composition, wherein the equimolar amount of the anion is the molar amount of the anion multiplied by its valency; and mixing said solution of hypochlorite oxidizing agent with said composition.

28. 28. The method of claim 27, wherein the hypochlorite oxidizing agent is sodium hypochlorite.

29. 29. The method of claim 27 or 28, wherein the hypochlorite oxidizing agent solution has a concentration ranging from about 1000 to about 20,000 ppm.

30. 30. The method of any one of claims 27 to 29, wherein the hypochlorite oxidizing agent solution has a concentration ranging from about 3000 to about 10,000 ppm.

31. 31. The method of any one of claims 27 to 30, wherein the hypochlorite oxidizing agent solution has a concentration ranging from about 3500 to about 7000 ppm.

32. 32. The method of any one of claims 27 to 31, wherein the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium bromide, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium phosphate, ammonium sulfamate, and ammonium sulfate.

33. 33. The method of any one of claims 27 to 32, wherein the ammonium salt is selected from the group consisting of ammonium bromide, ammonium carbamate, ammonium chloride, and ammonium sulfate.

34. 34. The method of any one of claims 27 to 33, wherein the ammonium salt is selected from the group consisting of ammonium bromide and ammonium carbamate.

35. The composition comprises: combining an ammonium salt stock solution, an aqueous ammonia stock solution, and sodium bicarbonate to form a mixture; and diluting the mixture with water or a solution of the hypochlorite oxidizing agent.

36. 36. The method of claim 35, wherein the ammonium salt stock solution has a concentration ranging from about 15% w / w to about 50% w / w.

37. 37. The method of claim 35 or 36, wherein the ammonium salt stock solution has a concentration ranging from about 20% w / w to about 35% w / w.

38. 38. The method of any one of claims 35 to 37, wherein the aqueous ammonia stock solution has a concentration ranging from about 4% w / w to about 28% w / w.

39. 39. The method of any one of claims 35 to 38, wherein the aqueous ammonia stock solution has a concentration of about 8.33 w / w%.

40. 40. The method of any one of claims 35 to 39, wherein the ammonium salt stock solution and the aqueous ammonia stock solution are equimolar.

41. 41. The method of any one of claims 35 to 40, wherein the molar ratio of the ammonium salt to the aqueous ammonia in the mixture ranges from about 1:10 to about 10:

1.

42. 42. The method of any one of claims 35 to 41, wherein the molar ratio of the ammonium salt to the aqueous ammonia in the mixture ranges from about 1:3 to about 3:

1.

43. 43. The method of any one of claims 35 to 42, wherein the concentration of the sodium bicarbonate in the mixture ranges from about 0.2% w / v to about 10% w / v.

44. 44. The method of any one of claims 35 to 43, wherein the concentration of the sodium bicarbonate in the mixture ranges from about 1% w / v to about 5% w / v.

45. 45. The method of any one of claims 27 to 44, further comprising monitoring a control parameter during said mixing.

46. 46. The method of claim 45, wherein the control parameter is selected from the group consisting of pH, oxidation-reduction potential (ORP), conductivity, dissolved oxygen saturation, and ORP / pH ratio.

47. 47. The method of claim 46, wherein the control parameter is the ORP / pH ratio.

48. 47. The method of claim 46, wherein the control parameter is conductivity.

49. The mixing step comprises: adding the hypochlorite oxidizing agent solution to the composition; and ceasing the addition of the hypochlorite oxidizing agent solution when the conductivity reaches a relative maximum value.

50. 50. The method of claim 49, wherein the conductivity reaches a relative minimum before reaching the relative maximum.

51. A method according to any one of claims 27 to 50, wherein the pH of the biocide remains below 12.5.

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