EP4638367A1 - In situ methods for eliminating biuret in aqueous liquids - Google Patents

Abstract

The instant disclosure is related to, inter alia, methods for remediating biuret in aqueous liquids/solutions, methods for remediating cyanuric acid and biuret in aqueous liquids/solutions. Certain one or more embodiments or aspects of the disclosure are directed to methods for remediating biuret in freshwater swimming pools, saltwater swimming pools and the like.

Description

IN SITU METHODS FOR ELIMINATING BIURET IN AQUEOUS LIQUIDS

TECHNICAL FIELD

[0001] The present disclosure is generally related to the fields of inorganic chemistry, organic chemistry, reduction/oxidation (redox) chemistry, chlorinated water treatment processes and the like. More particularly, certain embodiments of the disclosure are related to methods for reducing or eliminating biuret in aqueous liquids such as swimming pool water, hot tub water and the like. As set forth herein, the methods of the present disclosure are particularly useful for remediating biuret in aqueous liquids.

CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims benefit to U.S. Provisional Patent Application No. 63/476,078, filed December 19, 2022, which is incorporated herein by referenced in its entirety.

BACKGROUND OF THE DISCLOSURE

[0003] As generally known in the ait, chlorine is often added to aqueous solutions (e.g., swimming pool water; hot tub water, treated wastewater) as an antimicrobial agent, thereby mitigating the spread of such microorganisms (Gardiner, 1973). However, free chlorine in an aqueous solution is rapidly photodegraded by UV sunlight and/or high temperatures, and as such, chlorine stabilizers are necessarily added to the aqueous solution to mitigate such photochemical decomposition of the chlorine. Chlorine stabilizers such as cyanuric acids are therefore widely used in water treatment programs to mitigate photochemical decomposition of the free chlorine. To maintain adequate chlorine disinfection in the aqueous solution, it becomes essential to remove cyanuric acid (CYA) when its concentration generally rises above 100 ppm. For example, the accepted CYA working range is generally above 40 ppm and below 100 ppm, i.e., due to the equilibrium between cyanuric acid and hypochlorite resulting in sequestration of most reactive (free) chlorine species (i.e., chlorine “lock”) at high cyanuric acid concentrations.

[0004] In certain aspects, the use of cyanuric acid as a chlorine stabilizer is aqueous liquids, such as swimming pools and hot tubs, can result in the production/formation of biuret (allophanamide; C2H5N3O2). In particular, biuret (C2H5N3O2) is formed from a condensation reaction of two (2) molecules of urea (CO(NH₂)₂), and resultant loss of an ammonia (NH3) molecule e.g., see Guo et al., 2022). Biuret is also produced when enzymes having cyanuric acid amidohydrolase activity are used to mitigate/reduce cyanuric acid (CYA) concentrations in aqueous solutions (e.g., swimming pool water; hot tub water, etc.). For example, the biodegradation of CYA via CYA amidohydrolases can result in the buildup of the hydrolysis product biuret, wherein biuret also binds active chlorine, enhancing (unwanted) chlorine lock. [0005] Presently, the most effective means to mitigate or remove biuret in swimming pool water is to partially, or completely drain the swimming pool water, and then refill with clean water, or by adding a sufficient amount of hypochlorous acid (or a salt thereof) to remediate the biuret in the aqueous liquid. As appreciated by one of skill in the art, the use and administration of hypochlorous acid in amounts/quantities sufficient to remediate biuret in aqueous liquids may not always be safe for the end users of such products. Based on the foregoing, it is apparent that there remain ongoing and unmet needs in the art, such as safe, efficient, and cost-effective methods for remediating biuret in aqueous liquids.

SUMMARY OF THE DISCLORE

[0006] The preset disclosure provides, inter alia, methods for remediating biuret in aqueous liquids/solutions, methods for remediating cyanuric acid (CYA) and biuret in aqueous liquids/solutions, and the like. In certain one or more embodiments or aspects, the disclosure is related to remediating biuret and/or remediating CYA and biuret in aqueous liquids/solutions such as swimming pools, and hot tubs. Certain one or more embodiments or aspects of the disclosure are therefore related to methods for remediating biuret in saltwater swimming pools and/or a freshwater swimming pools.

[0007] In certain embodiments, methods for remediating biuret include adding sodium chloride (NaCl) to the aqueous liquid comprising the biuret to form an aqueous (saltwater) liquid composition comprising the biuret and about 0.3% saltwater, and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the aqueous liquid composition. Certain other embodiments are related to methods for remediating CYA and biuret in an aqueous liquid comprising contacting the aqueous liquid with an enzyme comprising cyanuric acid hydrolase (CAH) activity, wherein the CAH catalyzes the hydrolysis of CYA to biuret, adding sodium chloride (NaCl) to the aqueous liquid comprising biuret to form an aqueous saltwater liquid composition comprising the biuret and about 0.3% saltwater, and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the aqueous liquid composition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 shows the average concentration (parts per million; ppm) of cyanuric acid (CYA; filled circles, solid line) and biuret (open squares, dashed line) in 0.3% saltwater over time, following the addition of cyanuric acid hydrolase (CAH) at 21 °C. As indicated in FIG. 1, full conversion of the cyanuric acid to biuret was achieved after about 150 minutes of cyanuric acid hydrolase (enzyme) incubation. [0009] Figure 2 shows the average concentration of enzymatically produced biuret (ppm) in 0.3% saltwater during electrochlorination process (16V, 0.44 A, DC). As indicated in FIG. 2, complete remediation of biuret was achieved after about ten minutes.

[0010] Figure 3 shows the average concentration (ppm) of cyanuric acid (CYA; filled diamonds, solid line) and biuret (open triangles, dashed line) in water over time, following the addition of CAH at 21 °C. As indicated in FIG. 3, full conversion of the cyanuric acid to biuret was achieved after approximately 150 minutes. Likewise, as shown in FIG. 3, immediately following the 150-minute incubation period, 0.0825% sodium hypochlorite was added to fully eliminate (remediate) the enzymatically produced biuret.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0011] As presented and exemplified herein, the present disclosure addresses ongoing and unmet needs in the art related to biuret remediation in aqueous liquids. For instance, as briefly described above, chlorine stabilizers such as cyanuric acid (CYA) are often used in the disinfection process of aqueous liquids (e.g., swimming pool water, hot tub water, etc.), and when the CYA concentration becomes too high, cyanuric acid amidohydrolase (CAH) enzymes may be used lower the cyanuric acid (CYA) concentration in the aqueous liquid (e.g., see PCT Publication No. W02021/086605). However, following hydrolysis of the CYA by the CAH enzyme, a biuret product is formed in the aqueous liquid, wherein the biuret can bind active chlorine and enhance (unwanted) chlorine lock. Certain methods for remediating biuret from an aqueous solution by adding hypochlorite to the biuret containing solution have been described (Guo et al., 2022; PCT Publication No. W02021/161307).

[0012] Unfortunately, the use and/or administration of hypochlorous acid in amounts/quantities sufficient to remediate biuret in large volumes of aqueous liquids may not always be safe for the end users (e.g., pool technicians, pool/hot tub owners, etc.). Based on the foregoing, Applicant has contemplated, designed, and experimentally verified a novel method for safe, efficient, and cost-effective remediation of biuret in aqueous liquids. More particularly, as described hereinafter, and set forth in the Examples below, the present disclosure provides, inter alia, in situ electrochlorination processes suitable for remediating biuret in aqueous liquids. In certain one or more aspects or embodiments of the disclosure, such electrochlorination processes are electrochlorination processes/methods described herein.

I. DEFINITIONS

[0013] Prior to describing the present compositions and methods in detail, the following terms are defined for clarity. Terms not defined should be accorded their ordinary meanings as used in the relevant art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present compositions and methods apply- [0014] Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present compositions and methods, representative illustrative methods and materials are now described. All publications and patents cited herein are incorporated by reference in their entirety.

[0015] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only”, “excluding”, “not including” and the like, in connection with the recitation of claim elements, or use of a “negative” limitation or proviso thereof.

[0016] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present compositions and methods described herein. Any recited method can be carried out in the order of events recited, or in any other order which is logically possible.

[0017] As used herein, the terms “free chlorine” or “Cl” may be used interchangeably and are used herein to describe the free (unbound) chlorine (Cl) in an aqueous liquid, a highly effective antimicrobial agent comprising a wide biocidal activity.

[0018] As used herein, the term “hypochlorous acid” may be abbreviated as “HOC1” and is known to be a strong oxidant.

[0019] As used herein, the terms “hypochlorite” or “hypochlorite ion” may be abbreviated as “CIO-”, and is known to be a strong oxidant, at concentration ranges typically used in swimming pool disinfection processes, hot tub disinfection processes and the like.

[0020] As used herein, the phrases “hypochlorite concentration ranges typically used in swimming pool disinfection processes” and “hypochlorite concentration ranges typically used in hot tub disinfection processes”, generally refer to hypochlorite concentration ranges between about 1 ppm to about 5 ppm.

[0021 ] As used herein, the term “undetectable level(s)” as used in phrases such as contacting an aqueous liquid with a

[0022] As used herein, “cyanuric acid” (l,3,5-triazine-2,4,6-triol, abbreviated “CYA”) is a molecule having a chemical formula of (CNOH)3. Cyanuric acid is commonly used as part of water disinfectant processes, either as a precursor to and/or stabilizer of microbicidal chlorine ions. For example, CYA at lower concentrations (~30 ppm) acts as an effective stabilizer; but at higher concentrations (-100 ppm), CYA will trap (lock) chlorine (“chlorine lock”), greatly reducing its efficacy as a water disinfectant.

[0023] As used herein, “biuret”, also known as “allophanamide”, is a chemical compound (C2H5N3O2) which results from a condensation reaction of two (2) molecules of urea, and resultant loss of an ammonia molecule. Biuret is also the product obtained by treatment of cyanuric acid (CYA) in an aqueous liquid with an enzyme having CYA amidohydrolase activity.

[0024] As used herein, the term “electrochlorination” is the process of producing hypochlorite by passing electric current through salt water.

[0025] As used herein, an “effective amount of a compound” refers to a quantity of compound sufficient to achieve a desired effect in an environment, such as a body of water. An effective amount of a compound can be provided in a single amount, or in several amounts. However, the total effective amount of the compound will be dependent on the compound applied and the desired effect.

[0026] As used herein, the term “elimination” does not require absolute removal of an unwanted substance from a mixture, solution, liquid, water or sample; rather, it is intended as a relative term. Thus, in particular embodiments, the elimination of biuret does not require 100% removal of biuret. It can be understood that the elimination of biuret is removal of biuret until ppm levels have been achieved that are considered not to interfere with the active chlorine levels, for example below 10 ppm, optimally 2 ppm or below.

[0027] As used herein, the term “contacting” as used in phrases such as “contacting an aqueous liquid”, “contacting pool water” and the like, is not meant to be limiting. Thus, as used herein, the term “contacting” includes any means of administering or dispensing one or more molecules of the disclosure. For example, in certain embodiments, contacting includes mixing/distributing one or more enzyme(s), sodium chloride (Nad) salts, and the like.

[0028] As used herein, the term “circulating reservoir” refers to a structure for holding a relatively large amount of water. More particularly, given the large volume of water in such circulating reservoirs, it is highly desirable that the water does not have to be replaced after every use, and more preferably that the water does not have to be replaced all. In general, to maintain the water in a circulating reservoir' (e.g. swimming pool water), the water is typically pumped or otherwise circulated in the reservoir (e.g., through a filtration system, etc.).

[0029] As used herein, a “swimming pool”, a “hot tub” and the like may be referred to as a “circulating reservoir”, wherein the reservoir water is circulated by means of water pumping systems and the like. More particularly, for the reservoir' water to remain clean and clear-, the entire (total) volume of the water must be completely filtered at least once a day, which is referred to in the art as the “turnover rate”.

[0030] In general, most swimming pool and hot tub water pumps have a one (1) day turnover rate or less (e.g., 16 hours, 12 hours, 8 hours). For example, the equation “total water volume (gallons) divided by turn over time (hours)” may be used to estimate water pump flow rate needed to completely circulate (turn over) the water in the reservoir in the given amount of turn over time. As an example, to determine a water pump flow rate (gallons per hour; GPH) needed to completely circulate (turn over) the water in a 10,000 gallons swimming pool in a eight (8) hour period of time, the total volume of the water (10,000 gallons) is divided by desired turn over time (8 hours) yielding a flow rate of 1 ,250 GPH needed to turn over the water in an eight (8) hour period of time, to completely circulate (turn over) the water in a 10,000 gallons swimming pool in a twelve (12) hour period of time, the volume of the water (10,000 gallons) is divided by twelve (12), yielding a flow rate of 833 GPH, and to completely circulate (turn over) the water in a 10,000 gallons swimming pool in a twenty-four (24) hour period of time, the volume of the water (10,000 gallons) is divided by twenty-four (24), yielding a flow rate of 416 GPH.

[0031] As used herein, the term “sufficient period of time” as used in phrases such performing an electrochlorination process for a “sufficient period of time to lower the biuret concentration” in an aqueous liquid. For example, in certain embodiments, an electrochlorination process is performed on an aqueous (saltwater) liquid comprising biuret for a sufficient period of time to significantly lower the biuret concentration in the saltwater and/or completely eliminate the biuret in the saltwater composition. In certain aspects or embodiments, a sufficient period of time to lower the biuret concentration in an aqueous liquid is generally dependent upon the selected electrochlorination process/method used.

II. METHODS FOR REMEDIATING BIURET IN AQUEOUS LIQUIDS

[0032] As generally described in PCT Publication No. W02021/086605, the use of the halogen chlorine as an antimicrobial agent is known in the art for its multiple mechanisms of microbial killing, thereby mitigating the spread of microorganisms such bacteria, fungi, viruses, parasites, and the like (Brady et al., 1963; Gardiner, 1973). For example, when used as an antimicrobial agent in aqueous liquids such as swimming pool water, chlorine is often introduced into the water in the form of hypochlorous acid (HOC1; or a salt thereof, NaOCl), which dissociates into the hypochlorite (CIO-) anion. Likewise, in order to mitigate the otherwise rapid photo degradation of the hypochlorite (CIO-) in the water, chlorine stabilizers such as cyanuric acid are introduced into the water, thereby significantly slowing the chlorine/hypochlorite degradation process. Thus, to maintain proper chlorine levels for effective water disinfection processes (and slow the Cl degradation process), a balance must be struck between the level of cyanuric acid stabilizers in the water relative to the amount of free (unbound) chlorine in the water.

[0033] As set forth in W02021/086605, addition of cyanuric acid (stabilizers) to the pool water slows the degradation process, but the chlorine still degrades over time and must be replenished continuously throughout the pool water operational period. For instance, the most common and convenient means of introducing and replenishing chlorine in the water is in the form of cyanuric acid (CYA), wherein the level of the CYA stabilizer keeps rising with each cycle of chlorine replenishment. This scenario eventually results in the over stabilization of the chlorine (i.e., “chlorine lock”), with concomitant loss of chlorine disinfection properties in the water. Certain methods to remove (remediate) cyanuric acid in an aqueous solution when its concentration is too high include the use of enzymes, such as cyanuric acid hydrolase (CAH) enzymes (e.g., see PCT Publication No. W02016/141026 and Seffernik et al., 2012, each incorporated herein by reference). For example, as shown below in Scheme 1 and further described in Bera et al. (2017) and Aukema et al. (2020), the CAH enzyme catalyzes the hydrolytic ring-opening of cyanuric acid (CYA; left side of reaction arrow), resulting in the formation of biuret and CO2 (biuret; right side of reaction arrow).

[0034] As briefly described above, the biuret product formed in the aqueous liquid (e.g., swimming pool water) can bind the active chlorine in the water, thereby enhancing unwanted chlorine lock. Certain methods for remediating biuret (mitigating chlorine lock) from an aqueous solution include adding hypochlorous acid/hypochlorite to the biuret containing solution. However, these methods may not be suitable or safe for many end users, such as swimming pool technicians, swimming pool/hot tub owners, etc. Based on the foregoing, Applicant has contemplated, designed, and experimentally verified a novel method for safe, efficient, and cost-effective remediation of biuret in aqueous liquids. More particularly, as described hereinafter, and set forth in the Examples below, the present disclosure provides, inter alia, in situ electrochlorination processes suitable for remediating biuret in aqueous liquids. In certain one or more aspects or embodiments of the disclosure, such electrochlorination processes are electrochlorination processes/methods described herein.

[0035] As described in Example 1, the enzymatic production of biuret was performed via hydrolysis of cyanuric acid (CYA) using a cyanuric acid hydrolase (CAH) in about 0.3% saltwater (sodium chloride; NaCl), wherein the CAH (enzyme) was produced by the procedure described in Guo et al. (2022). For example, the CYA stabilizer was dissolved in saltwater (0.3% sodium chloride; pH 7.0) to about 190 ppm. To this solution, a portion of CAH was added, and the conversion of CYA to biuret was followed by HPLC (FIG. 1), wherein all of the CYA added (FIG. 1, filled circles) was enzymatically converted to biuret (FIG. 1, open squares).

[0036] As generally set forth below in Example 2, Applicant further demonstrates substantial hypochlorite production via an electrolytic process in the same solution as used for the enzymatic hydrolysis of CYA

7

SUBSTITUTE SHEET (RULE 26) described in Example 1. In particular, the generation (electrochlorination) of active chlorine (hypochlorite) was measured using chromogenic dip sticks after ten (10) minutes of electrolysis of 0.3% saltwater (pH 7.0). For instance, by visual inspection and comparison of the color generated on the dip stick to the color charts of the dipstick kit, the “total chlorine” was estimated to be about five (5) ppm and “free chlorine” was estimated to be about three (3) ppm. More particularly, as shown in FIG. 2, the complete remediation of biuret was achieved after about ten (10) minutes of the electrochlorination process.

[0037] As further described in Example 2, a control experiment was performed wherein the biuret was produced from enzymatically hydrolyzed CYA via CAH enzyme (as described in Example 1), but without the 0.3% saltwater, or the electrolytic process. More particularly, the average concentration of enzymatically produced biuret was followed by HPLC analysis (FIG. 3, open triangles). For an internal control, the experiment was performed using chemically prepared hypochlorite to remediate the enzymatically generated biuret (FIG. 3, filled black arrow). For example, as presented in FIG. 3, 10 pl of 8.25% hypochlorite was added to 990 pl reaction volume at the time indicated with the arrow (-150 hours), vortexed for ten (10) seconds, and analyzed by HPLC. As indicated in FIG. 3, the full conversion of the CYA to biuret was achieved after approximately 150 minutes.

EXAMPLES

|0038| Certain aspects of the present disclosure may be further understood in light of the following examples, which should not be construed as limiting. Modifications to materials and methods will be apparent to those skilled in the art.

EXAMPLE 1

ENZYMATIC PRODUCTION OF BIURET BY HYDROLYSIS OF CYANURIC ACID USING A CYANURIC ACID HYDROLASE IN SALTWATER

[0039] The instant example describes the enzymatic production of biuret via hydrolysis of cyanuric acid (CYA) using cyanuric acid hydrolase (CAH) in 0.3% saltwater (sodium chloride). More particularly, the enzymatic production of biuret was performed via hydrolysis of cyanuric acid (CYA) using a cyanuric acid hydrolase (CAH) in about 0.3% saltwater (sodium chloride; NaCl), wherein the CAH (enzyme) was produced by the procedure described in Guo et al. 2022 (specifically incorporated herein by reference in its entirety). For example, the CYA stabilizer was dissolved in saltwater (0.3% NaCl; pH 7.0) to about 190 ppm. To this CYA/saltwater solution a portion of CAH was added and the conversion of CYA to biuret was followed by HPLC (FIG. 1). As presented in FIG. 1, the average concentration (ppm) of CYA (filled circles, solid line) and biuret (open squares, dashed line) in 0.3% saltwater was followed over time after the addition of cyanuric acid hydrolase (CAH) at 21 °C, wherein full conversion of the cyanuric acid to biuret was achieved after about 150 minutes of CAH (enzyme) incubation.

EXAMPLE 2

BIURET REMEDIATION USING AN ELECTROLYTIC PROCESS

[0040] The instant example describes and demonstrates substantial hypochlorite production and biuret remediation via an electrolytic process in the same solution as used for the enzymatic hydrolysis of CYA described in Example 1. In particular, the generation of active chlorine (hypochlorite) was achieved using an electrolytic process (per manufacturer's recommendations, Microbial H Cell, Product Code #1081102, Microbial fuel cell with platinum electrode). Conformation of hypochlorite generation was established using a chromogenic dipstick kit. The color generated on the dip stick was compared to the color charts of the dipstick kit, the total chlorine was estimated to be about five (5) ppm and free chlorine was estimated to be about three (3) ppm. More particularly, as shown in FIG. 2, the complete remediation of biuret was achieved after about ten (10) minutes of the electrolytic process. Thus, as demonstrated in this example, the electrolysis of saltwater is a particularly useful process to produce active chlorine (hypochlorite), wherein the active chlorine produced by the electrochlorination process is capable of completely eliminating (remediating) biuret in the aqueous liquid after about ten minutes (FIG. 2).

[0041 ] In addition, a control experiment was performed wherein the biuret was produced from enzymatically hydrolyzed CYA via CAH enzyme (as described in Example 1), but without the 0.3% saltwater or the electrolytic process. More particularly, the average concentration of enzymatically produced biuret was followed by HPLC analysis (FIG. 3, open triangles). For an internal control, the experiment was performed using chemically prepared hypochlorite to remediate the enzymatically generated biuret (FIG. 3, filled black arrow). For example, as presented in FIG. 3, 10 pl of 8.25% hypochlorite was added to 990 pl reaction volume at the time indicated with the arrow (-150 minutes), vortexed for 10 seconds, and analyzed by HPLC. As indicated in FIG. 3, the full conversion of the CYA to biuret was achieved after approximately 150 minutes.

REFERENCES

PCT Publication No. W02007/107981

PCT Publication No. W02016/141026

PCT Publication No. W02021/086605

PCT Publication No. W02021/161307

Aukema et al., “Cyanuric Acid Biodegradation via Biuret: Physiology, Taxonomy, and Geospatial Distribution”, Applied and Environmental Microbiology, Vol. 86, Issue 2, 2020.

Bera et al., “Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel”, Scientific Reports, Vol. 7, Number 45277, 2017.

Gardiner, “Chloroisocyanurates in the Treatment of Swimming Pool Water”, J. American Chemical Society, 85(20):3101-3104, 1973

Guo et al.. “A procedure for removal of cyanuric acid in swimming pools using a cell-free thermostable cyanuric acid hydrolase”, J. Industrial Microbiology and Biotechnology, Vol. 49, 2022.

Seffernik et al., “Defining Sequence Space and Reaction Products withing the Cyanuric Acid Hydrolase (AtzD)/Barbiturase Protein Family” J. Bacteriology, 194(17): 4579-4588, 2012.

Claims

1. A method for remediating biuret in an aqueous liquid comprising: adding sodium chloride (NaCl) to an aqueous liquid comprising biuret to form an aqueous saltwater composition comprising the biuret and about 0.3% saltwater and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the aqueous liquid composition.

2. A method for remediating biuret in a saltwater swimming pool comprising: adjusting the sodium chloride (NaCl) concentration of the saltwater to about 0.3% NaCl, wherein the saltwater comprises biuret and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the saltwater swimming pool.

3. A method for remediating cyanuric acid (CYA) and biuret in an aqueous liquid, the method comprising:

(a) contacting the aqueous liquid with an enzyme comprising cyanuric acid hydrolase (CAH) activity, wherein the CAH catalyzes the hydrolysis of CYA to biuret,

(b) adding sodium chloride (NaCl) to the aqueous liquid comprising biuret to form an aqueous saltwater composition comprising the biuret and about 0.3% saltwater and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the aqueous liquid composition.

4. A method for remediating cyanuric acid (CYA) and biuret in a saltwater swimming pool comprising:

(a) contacting the aqueous liquid with an enzyme comprising cyanuric acid hydrolase (CAH) activity, wherein the CAH catalyzes the hydrolysis of CYA to biuret,

(b) adjusting the sodium chloride (NaCl) concentration of saltwater to about 0.3% NaCl, and performing an in situ electrochlorination process on the saltwater composition, wherein the electrochlorination process produces free (active) hypochlorite in the saltwater, thereby remediating the biuret in the saltwater swimming pool.