Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/008—Control or steering systems not provided for elsewhere in subclass C02F
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
  • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
  • C02F1/722—Oxidation by peroxides
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/42—Nature of the water, waste water, sewage or sludge to be treated from bathing facilities, e.g. swimming pools
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/003—Downstream control, i.e. outlet monitoring, e.g. to check the treating agents, such as halogens or ozone, leaving the process
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/02—Temperature
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/04—Oxidation reduction potential [ORP]
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/06—Controlling or monitoring parameters in water treatment pH

Definitions

• This invention relates to the maintenance of aquatic facilities, particularly to the optimization ofthe feed rates of a sanitizer/oxidizer and peroxygen compound, and most particularly to the incorporation of a coagulant effective to reduce oxidizer demand.
• closed recirculating water reservoirs for use by the general public, for example, swimming pools, spas, hot tubs, decorative fountains, cooling towers and the like, can lead to a variety of water quality problems. For instance, improper chemical balances in the water can lead to various types of contamination including bacterial and viral contamination.
• the difficulties in maintaining a proper balance of sanitizers may arise from numerous load factors that are difficult, if not impossible, to predict. For instance, in a pool the load factor is typically caused by varying numbers of users. In hot tubs the use of air jets and high water temperatures tend to destroy or remove the sanitizer from the water. Cooling towers can be subject to environmental conditions, such as fluctuations in temperature. Indoor decorative fountains may be affected by the air quality in the building, while the fountain water can also affect the air in the building.
• Various testing devices exist for determining the chemical balance ofthe water of pools, spas and the like, for example, colorimetric chemical test kits are available that utilize liquid droplets, test strips or tablets which dissolve in the water to indicate a particular level or concentration of sanitizing agents.
• a staining agent is then added by means such as an eye dropper or the like.
• the degree of staining relates to the amount of sanitizer in the water.
• the amount of sanitizer present is determined by visually comparing the degree of coloring ofthe test sample against a test scale previously formulated.
• U.S. Patent No. 4,752,740 suggests the use of monitoring the oxidation-reduction potential (ORP) as a method of measuring the sanitization levels of water.
• ORP oxidation-reduction potential
• the present invention provides a process for treating water systems.
• the method comprises the steps of monitoring the ORP ofthe water system, comparing the monitored ORP to a set-point value calculated to be within a range effective to permit oxidation of said halogenated compounds, adding a halogen donor source in an amount and at a rate sufficient to realize an optimum free halogen level sufficient to sanitize water in the water system and adding a coagulating agent in an amount effective to reduce the amount of halogen donor required to maintain the ORP within said effective range.
• Figure 2 is a Circuit Diagram ofthe Air and Water Flow in the test device according to Example 1 ;
• Figure 3 is a graphical representation of actual field conditions at the facility described in Example 5 prior to incorporating the teachings ofthe instant invention
• Figure 4 is a graphical representation of actual field conditions at the facility described in Example 5 subsequent to incorporating the teachings ofthe instant invention.
• ORP defines the potential of a sanitizer such as chlorine, bromine or ozone to react with various contaminants. These compounds are known as oxidizers and have the property of "burning off' impurities in the water, for example, body wastes, algae and bacteria.
• ORP sensor allows the pool maintenance engineer to measure the potential generated by the active form ofthe sanitizer and not the inactive forms such as the combined chlorine derivatives.
• ORP monitoring has an advantage in that it can be an ongoing electronic process requiring no test chemicals or agents and monitoring of sanitation levels can be constantly performed as opposed to being performed on some predetermined schedule basis.
• ORP measurement can reduce the risk of contamination and disease transmission.
• maintenance of an ORP level of 650 millivolts (mN) can be deemed to result in a water supply that should be disinfected and in which viral inactivation should be virtually instantaneous.
• Chlorine is believed to be the most widely used oxidizer in the aquatic industry, the primary use being for sanitation ofthe water in pools and spas. Chlorine, being an oxidizer, can also be involved in oxidation reactions with various organics, as well as inorganic and organic nitrogen based substances such as, but not limited to, urea, uric acid, amino acids, etc.
• the use of chlorine can result in the production of chlorinated byproducts as one consequence of incomplete oxidation. These byproducts are typically volatile and can produce undesirable side effects such as irritation ofthe eyes, sinuses, skin, foul smelling air, and corrosion of air handling equipment.
• the health department generally regulates the concentration of free (HOCL & OCL) chlorine in the water.
• HOCL free
• OCL oxygen-containing compound
• sufficient HOCL may not be available to maintain a sufficient rate of oxidation ofthe demand being contributed to the water. This allows for the accumulation of these undesirable substances.
• this method fails to rid the water and air of these substances since the concentration of chlorine required is at best a rough estimate (incorporates measuring the combine chlorine in the water.) Measuring the concentration of combined chlorine in the water does not take into consideration the accumulated demand that is non-aqueous, e.g. that accumulated on the filter media, walls ofthe pools, etc. As the chlorine levels rise, some ofthe accumulated demand is liberated. This gives the appearance that the system had not been driving breakpoint when indeed it probably did for awhile. The fact that the free chlorine levels drop considerably, and the combined chlorine level still appears, can be an indication that the HOCL must have oxidized the combined chlorine and/or accumulated demand, thereby providing a source of readily available oxidizable substances not originally detected in the water.
• Bromine can be used in place of chlorine because ofthe belief that it does not produce the air fouling byproducts produced by chlorine.
• bromamines are typically not as volatile as chloramines, they can possess an odor and can irritate the eyes.
• Bromine also typically requires an oxidizer such as, but not limited to, chlorine or ozone to activate the bromide ion. Operating costs tend to be high and it can be difficult to maintain water quality because, it is believed, ofthe difficulty in differentiating between free or combined bromine.
• hydantoin an additive that can be used to pelletize the bromine chlorine combination, can reduce the oxidizing power ofthe bromine, as the hydantoin accumulates in the water. This makes it more difficult to reduce the accumulation of undesirable brominated compounds.
• Non-chlorine shock treatments incorporating peroxygen compounds e.g. potassium monopersulfate (MPS), such as OXY-BRITE ® bleach, available from Great Lakes Biochemicals, can be used for addressing the chloramine issue.
• MPS potassium monopersulfate
• OXY-BRITE ® bleach available from Great Lakes Biochemicals
• MPS potassium monopersulfate
• the method of shock feeding can be a means of addressing the symptoms resulting after the problem makes them apparent, e.g. high chlorine concentration and foul odors.
• MPS in some cases, can be used as a shock treatment even while bathers are present.
• the system can experience undesirable side effects from MPS shock feeding.
• MPS can increase the ORP ofthe chlorine donor system.
• the ORP ofthe system can rise above that provided by the chlorine donors. It is believed that as long as the ORP value remains above the set point established for the chlorine donor system, no chlorine donor is fed. Since many ofthe contaminants entering the water do not react directly with MPS without first being oxidized by, for example, the chlorine donors, these substances further accumulate, thereby compounding the problem.
• This invention incorporates an innovative process that allows the aquatic facility to maintain the desired ORP and oxidize the chlorinated volatile substances in the bulk water, while not exceeding the free chlorine limits established by local health departments.
• This process can incorporate optimization ofthe rate of oxidation by controlling the feedrate and ratio of, in some embodiments, two oxidizers, a primary oxidizer being a halogen donor source, e.g. trichloroisocyanuric acid, dichloroisocyanuric acid, sodium bromide, hydantoin based bromines, gaseous chlorine, calcium hypochlorite, sodium hypochlorite, lithium hypochlorite and mixtures thereof; and other oxidizer being, in some embodiments, a peroxygen compound selected from, for example, hydrogen peroxide, sodium peroxide, sodium perborate, potassium monopersulfate, sodium peroxydisulfate, potassium peroxide, potassium perborate, sodium monopersulfate, potassium peroxydisulfate, ammonium peroxydisulfate, ammonium monopersulfate and mixtures thereof.
• the peroxygen compound is MPS.
• the ratio of MPS to halogen donor e.g. chlorine donors
• the ratio of MPS to halogen donor can be optimized to sustain the desired ppm range of chlorine, while achieving an ORP of 780 mN - 820 mN.
• the rate of oxidation can be maintained at a level that is sufficient to prevent the accumulation of undesirable halogenated byproducts.
• the process can optimize the ORP by incorporating the necessary process control and feed equipment to sustain a set-point, thereby controlling the concentration of undesirable by-products in the water.
• the process teaches the step of feeding coagulating agents to neutralize the charge density of water-soluble organic complexes thereby making them water-insoluble.
• the water-insoluble precipitates can be separated from the oxidizers utilizing, for example, settling, filtration, flocculation (agglomeration) followed by settling, or flocculation followed by filtration.
• the invention can eliminate volatile halogenated compounds from water and air by maintaining a level of oxidation potential.
• the feedrate and ratio of halogen donor and peroxygen compound can be optimized to sustain the desired ppm range of halogen and sustain an ORP of, for example, 780 mN - 820 mN. Sustaining these parameters should prevent or even reverse the accumulation of combined halogen and other halogenated volatile compounds, which contaminate the air and water of aquatic facilities, in particular indoor aquatic facilities.
• the demand for oxidizers can be substantially reduced by incorporation of a coagulating agent effective to reduce the demand for oxidizers by reducing the soluble (reactive) organic demand from the system.
• the present invention can provide for the controlled addition of coagulating agents and, in some embodiments, control the coagulant addition at an amount that optimizes or reduces the amount of halogen donors and the peroxygen compound, or both.
• the invention provides a process of operating an aquatic facility under conditions of "Continuous Breakpoint Halogenation and Peroxygenation.”
• the invention can improve the air quality around closed water systems by, for example, the removal of halogenated compounds through re-absorption followed by oxidation thereof with, e.g. HOCL.
• a typical indoor aquatic facility according to one embodiment ofthe present invention is characterized. Water from the pool or spa typically flows past an ORP sensor.
• the water may further flow past a sensor, which can measure any of total dissolved solids (TDS), temperature and pH.
• Output from the ORP sensor can be transmitted to a controller, which can call for the addition of any of a halogen donor source and a peroxygen source to the pool water in accordance with selected process parameters.
• controller can further regulate the addition of a coagulating agent.
• Oxidation Reduction Potential can be a qualitative measurement ofthe oxidation or reduction power of a solution. While ORP can be used as the primary indicator of determining the inactivation rates of various bacteria and viruses, dosing aquatic water with ppm measurement of halogen has been the method used for meeting the oxidation needs ofthe aquatic facility. For example, while 650 mN is commonly used as the minimum required oxidation potential to ensure sanitized conditions in a pool or spa, health departments typically still require ppm levels of halogen, e.g. chlorine.
• halogen e.g. chlorine
• the present invention incorporates optimizing the rate of oxidation by controlling the feedrate and ratio of, for example, two oxidizers, wherein the primary oxidizer is typically a halogen donor and the other can be a peroxygen compound, e.g. MPS.
• the ratio of MPS to halogen donor can be optimized to sustain the desired ppm range of halogen, while achieving an ORP of, in one embodiment, 780 mN - 820 mN.
• ORP an ORP of, in one embodiment, 780 mN - 820 mN.
• the rate of oxidation should be maintained at a level that is sufficient to prevent the accumulation of undesirable chlorinated byproducts. Accordingly, when the system and method ofthe present invention is applied to an aquatic facility, the effects of poor air and water quality can be reduced and even eliminated.
• Optimizing the ratio of halogen donor to peroxygen compound, while controlling their combined feedrate using ORP can effectively reduce or even eliminate the problems resulting from the accumulation of volatile halogenated substances. This can be achieved while maintaining lower ppm levels of free halogen than is otherwise required in a strictly halogen donor system.
• the present invention typically involves: achieving and sustaining an optimum concentration of free halogen, e.g. free chlorine, of between 0.2 ppm -10 ppm; addition of peroxygen to raise the solution's ORP to 750 mN - 850 mN, preferably 760 mN - 800 mN; controlling the feed of both oxidizers using an ORP controller; and optimizing the ratio of halogen donor to peroxygen compound to sustain the optimized halogen donor while achieving the desired ORP.
• free halogen e.g. free chlorine
• This invention can ensure a sustained high rate of oxidation in the bulk water of the pool, spas, and other aquatic water systems despite the presence of accumulated demand. It has been found that the undesirable byproducts should not be sustained in an environment possessing this level of oxidation potential. Therefore, by implementing this invention, the aquatic facility can be operated under "Continuous Breakpoint Chlorination.” By operating in the conditions described, the byproducts, which can result from intermediate steps in the continuing process of oxidation and can be produced during the initial step of oxidation, should not accumulate. While these byproducts can be initially produced, they should not accumulate, and shortly thereafter, are typically destroyed by the continued oxidation.
• halogen feedrates can be controlled below maximum regulated levels while preventing or even reversing the accumulation of combined halogen and other chlorinated volatile compounds which contaminate the air and water of aquatic facilities, in particular, indoor aquatic facilities.
• the present invention in another embodiment, provides for the feed of coagulating agents that can be used to neutralize the charge density of water-soluble organic complexes, thereby making them water-insoluble.
• the water-insoluble precipitates can be separated from the oxidizers utilizing, for example, settling, filtration, flocculation, agglomeration and, in some cases, followed by settling, or flocculation followed by filtration.
• the present invention can feed coagulating agent, sometimes referred to as a polymer, to the system, which can convert water-soluble organics into water-insoluble organics thereby allowing separation from the oxidizer.
• coagulating agent sometimes referred to as a polymer
• Reduced organic demand on oxidizer enhances the oxidation potential ofthe oxidizer and further enhances efficient continuation of breakpoint halogenation.
• the controlled addition ofthe coagulating agent can reduce, or optimize, the amount of halogen donor or peroxygen compound, or both.
• the present invention can, in some embodiments, further reduce any volatile byproducts associated with incomplete oxidation.
• the controlled addition of coagulation agents can reduce the amount of halogen donor or peroxygen compound addition and, thus, the likelihood of incomplete oxidation, which should reduce volatile byproducts.
• the coagulating agent can be fed at a sufficient frequency and level of concentration to allow halogen to remain in optimum range while sustaining desired ORP, e.g. within an effective range of 700 mN - 850 mN with chlorine levels in the range of 0J ppm - 10 ppm.
• the use of coagulating agents can significantly reduce the demand for oxidizers by removing the soluble (reactive) organic demand from the presence ofthe oxidizers.
• This practice can significantly reduce the use of oxidizers needed to oxidize the contaminants added to the pool to maintain air and water quality. Also, this practice can significantly reduced the concentration of free chlorine to maintain the ORP, while reducing the combined chlorine measured in the water.
• Useful coagulants include, for example, Alum, poly-aluminum chloride, sodium aluminate, polyamines, polyquaternary compounds, polydiallyl-dimethyl ammonium chloride, chitosan (poly-D-glucosamine) and chitin (poly-n-acetyl-D-glucosamine) alone or in any combination.
• the use of coagulating agents can enhance the existing described art, while further expanding the operating range of ORP to achieve continuous breakpoint halogenation.
• free chlorine concentration can be controlled by ORP, lower ORP set-points can be employed where desired while achieving continued Break-Point Halogenation, stoichiometric- based chemistry, without compromising performance.
• an ORP range of 700 mN - 850mN is attainable when utilizing this method.
• the coagulant dosage rates can be 0.01 ppm - 10 ppm.
• the coagulant may be fed to the system by any known method effective to introduce the coagulant to the water treatment system, such as, but not limited to, low level continuous feed, feed on demand, e.g. ORP activated, and periodic feed under timer based control.
• any known method effective to introduce the coagulant to the water treatment system such as, but not limited to, low level continuous feed, feed on demand, e.g. ORP activated, and periodic feed under timer based control.
• Example 1 A testing device was designed and built to simulate the water and air environment of an indoor aquatic facility. The system was designed to control the following: H 2 O temperature;
• Air circulation rates Air exchange rates; Water turnover rates (filtered water);
• Condensate samples were collected by chilling the air prior to the air circulation pump. Condensate was collected for 20 minutes; the measured sample was tested using standard DPD methods for chlorine that incorporated a Model DR/2000 spectrophotometer from HACH Company (Loveland, Colorado).
• Laboratory grade ammonium chloride was used as the nitrogen source for the generation of chloramines. A measured amount was added to the water ofthe test device. The water and air circulation pumps were activated and adjusted to achieve desired circulation and exchange rates.
• Results demonstrate that a comparable rate of chloramine destruction can be achieved while sustaining lower concentrations of free available chlorine, at an oxidation potential of approximately 780 mV.
• the two oxidizer approach in accordance with the teachings ofthe instant invention was then instituted using calcium hypochlorite and potassium monopersulfate.
• the oxidizers' feed rate was optimized to achieve the desired free chlorine concentration in the water (1.5 ppm - 2.0 ppm), while sustaining the targeted ORP of 780 mN using MPS.
• Example 3 A 72,000 gallon pool with zero depth entry, located near Denver, Colorado, experienced excessive bather use that produced undesirable air and water quality. The purpose of this treatment was to evaluate any reduction in the reactive water-soluble organic contaminants in the water, which should reduce the demand for halogen oxidizer.
• ECS Environmental Control System
• a Poly- Aluminum Chloride feed system was installed.
• the system was set to feed a low level, e.g. about 0.5 ppm based on circulation rate, of coagulant prior to the filter system.
• Example 4 A testing device was designed and built to simulate the water and air environment of an indoor aquatic facility.
• Figure 2 represents a circuit diagram of air and water flow through the test device. The system was designed to control the following: H 2 O temperature; Air circulation rates; Air exchange rates; Water turnover rates (filtered water);
• a condenser was installed in the air circulation system.
• the condenser allowed for scheduled sampling ofthe condensate.
• a micro-titration system was incorporated for precise feed of various reagents for adjusting ORP, pH, etc.
• the test device was initially prepared for use by the addition of water to 50 % ofthe skimmer line.
• the tank representing the surge pit was filled to 50 %.
• the tank lid was sealed.
• Condensate samples were collected by chilling the air prior to the air circulation pump. Condensate was collected for 20 minutes, the measured sample was tested using standard DPD methods for chlorine that incorporated a Model DR/2000 spectrophotometer from HACH Company (Loveland, Colorado).
• Laboratory grade ammonium chloride was used as the nitrogen source for the generation of chloramines. A measured amount was added to the water ofthe test device. The water and air circulation pumps were activated and adjusted to achieve desired circulation and exchange rates. A measured dosage of chlorine in the form of 5.25 % liquid bleach was added to the water to induce the formation of combined chlorine. After providing sufficient contact time, incremental dosages of bleach were added to achieve and sustain the desired ORP of 800 mN.
• Table 2 illustrates the rate of chloramine removal from the air (and subsequent water.) Sustaining the ORP at 800 mN with addition of a halogen donor (chlorine), the concentration of chloramines in the air was continually reduced over the test period. During the test period, the concentration of chloramines in the water was sustained, but did not accumulate. Mass balances calculations support the destruction of chloramines in the water equal to the rate of chloramine reduction in the condensate.
• chlorine halogen donor
• the water treatment system incorporated an ORP controller and used 12 % liquid bleach as the oxidant and sanitizer.
• Example 6 Laboratory grade glycine was added to a water sample to achieve about 62 ppm as glycine. Chlorine, in the form of calcium hypochlorite, was added to achieve 0.8 ppm free chlorine, measured using standard DPD methods. The corresponding chemistry was: pH - 7.95 ORP - 360 mN Free Chlorine - 0.8 ppm

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• Life Sciences & Earth Sciences (AREA)
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• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)
• Treating Waste Gases (AREA)

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• 2001
  • 2001-11-06 WO PCT/US2001/043720 patent/WO2002035908A2/en not_active Application Discontinuation
  • 2001-11-06 EP EP01992498A patent/EP1332112A2/de not_active Withdrawn
  • 2001-11-06 AU AU2002216705A patent/AU2002216705A1/en not_active Abandoned
  • 2001-11-06 CA CA002428058A patent/CA2428058A1/en not_active Abandoned

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