METHODS OF CLEANING AND SIMULTANEOUS DISINFECTION OF INDUSTRIAL WATER SYSTEMS FIELD OF THE INVENTION The present invention is located in the field of industrial water systems. Specifically, this invention is located in the field of cleaning and disinfection of industrial water systems. BACKGROUND OF THE INVENTION Around the world, there are many different types of industrial water systems. Water: industrial systems exist in such a way that chemical, mechanical and biological processes can be carried out to achieve the desired result. Fouling can occur even in industrial water systems with the best water treatment programs currently available. For purposes of this patent, "fouling" is defined as "the deposit of any organic or inorganic material on a surface". If these industrial water systems are not cleaned periodically, then they get dirty heavily. Soiling has a negative impact on the industrial water system. For example, a severe incrustation of mineral (inorganic material) will accumulate in the contact surfaces of the water and in any place that there is incrustation, there is an ideal environment for the growth of Ref.: 159625
microorganisms. Evaporative cooling water systems are particularly prone to fouling. This fouling occurs through a variety of mechanisms including deposition of pollutants suspended in the air and suspended in water and formed in water, water stagnation, process leaks, and other factors. If allowed to progress, the system may suffer from decreased operational efficiency, premature equipment failure, and increased health-related risks associated with microbial fouling. Soiling can also occur due to microbiological contamination. Sources of microbial contamination in industrial water systems are numerous and may include, but are not limited to, airborne contamination, water replenishment, process leaks and improperly washed equipment. These microorganisms can establish microbial communities on any surface that can get wet or that can get partially wet. Once these microbial populations are present in the water volume more than 99% of the microbes present in the water will be present on all surfaces. An exopoly substance secreted by microorganisms helps the formation of biofilms on the
surface when developing microbial communities. These biofilms are complex systems that provide a means to concentrate nutrients and offer protection for growth, and biofilms can accelerate scaling, corrosion, and other fouling processes. Not only do biofilms contribute to the reduction of system efficiencies, but they also provide an excellent environment for microbial proliferation that can include Legionella bacteria. Therefore it is important that biofilms and other fouling processes are reduced to the greatest extent possible to minimize the health-related risk associated with Legionella and other pathogens suspended in water. There are several different methods of cleaning or disinfection for cooling water systems. For example, mechanical cleaning, hyperhalogenation with and without surfactants or dispersants, and cleaning with acids, are among the most commonly used cleaning methods. A simple mechanical cleaning program consists of
"power cleaning" and "scrubbing". Power cleaning refers to the use of high pressure water directed at the surfaces of the equipment in such a way that the impact of water on the surface removes deposits from those surfaces that can be reached. Mechanical cleaning strategies are not always
remove all deposits that adhere strongly as deposits and biological sludge from equipment surfaces. Additional limitations in the use of mechanical cleaning include the fact that such methods are effective for removing only loose deposits, and not to remove deposits in the landfill (in the case of a cooling tower). For systems such as domestic water distribution pipe, power washing is completely ineffective. Mechanical cleaning methods also do not provide a means of disinfection, which is crucial to keep the equipment clean and safe. A standard procedure using hyperhalogenation and surfactant is commonly known as the "Wisconsin Protocol", see "CONTROL OF LEGIONELA IN COOLING TOWERS", Summary Guidelines, Epidemiology Section of Acute and Communicable Diseases, Bureau of Health and Community Prevention, Division of Health, Wisconsin Department of Health and Social Services, August 1987. The Wisconsin protocol is used to disinfect an industrial water system as a consequence of an outbreak of legionellosis. Even in the absence of an outbreak, hyperhalogenation is commonly used to reduce microbial fouling in water systems. Hyperhalogenation protocols do not remove mineral scale, thus limiting their ability to remove or reduce dirt.
biological In addition, hyperhalogenation procedures that require a biodispersant have limited effectiveness in the period in which the protocol is implemented. The use of certain acids, such as sulfuric acid, in combination with doses of halogens, as specified in the Wisconsin Protocol, may form copper sulfate and other deposits that are subsequently difficult to remove. Finally, because hyperhalogenation methods do not remove scale and other deposits, microbial populations are rapidly re-established in the systems. An "acid cleaning procedure" is designed to remove mineral scale. The acid is able to remove alkaline scale from virtually all surfaces that can get wet. Acid cleaning procedures offer limited disinfection due to low pH, but do not properly penetrate biological deposits (biofilms) that remain associated with the surfaces of the system. Operators of industrial water systems use chlorine dioxide to kill microorganisms. Chlorine dioxide is a well-known biocide, but it does not have the ability to remove mineral scale. Chlorine dioxide must be generated at the site where it is applied. There are several methods to generate and supply chlorine dioxide. One of these methods uses acid in combination with chlorite
sodium (acid activation). For example, chlorine dioxide is generated using sodium chlorite and hydrochloric acid as follows: 5 NaC102 + 4 HC1 = 4 C102 + 5 NaCl + 2 H; 0 Typically, the reactants (sodium chlorite and hydrochloric acid) are mixed and they are allowed to react to form chlorine dioxide. Following this reaction, the products (sodium dioxide, sodium chloride, water, some remaining unreacted sodium chlorite, and hydrochloric acid) are added directly into the water of the industrial water system. Once this solution of chlorine dioxide generated externally is applied to the water system, the chlorine dioxide is diluted and lost through volatility or reduced by substances found in the water system. Using this method, chlorine dioxide must be constantly generated outside the water system, and injected into the system to maintain a residual chlorine dioxide. The Patent Cooperation Treaty Application WO 02/12130 Al discloses and claims a method of treating water in a water distribution system, comprising: mixing a sodium chlorite solution with a second solution containing an acid to make a reacted mixture; and enter a predetermined amount of mixture
reacted within a water system. As described in this Patent Cooperation Treaty Application, the preferred method of water treatment includes the addition of a catalyst, wherein the catalyst is sodium molybdate. U.S. Patent Application No. 2,313,369 describes and claims an aqueous composition having a pH greater than 9 and consists of a precursor of stabilized chlorine dioxide, an alkali metal polyphosphate and an alkali metal hydroxide. It also discloses and claims a method of treating water in a water distribution system comprising the addition of an acid activator to the aqueous composition to reduce the pH to less than 7 and to inject the aqueous solution into the water system. It would be desirable to have a method for simultaneously cleaning and disinfecting an industrial water system. BRIEF DESCRIPTION OF THE INVENTION The first aspect of the claimed invention is a method of simultaneous cleaning and disinfection of an industrial water system comprising the steps of: a) providing an industrial water system; b) adding to the water of that industrial water system i) a compound, wherein the compound is selected from the group consisting of alkali salts of chlorite and chlorate, or a mixture
from the same; and ii) an acid; wherein the acid is added before the compound is added; and c) allowing water to circulate through the industrial water system for at least about one hour to about 72 hours; and d) drain the water from the industrial water system. The second aspect of the claimed invention is a simultaneous cleaning and disinfection method of an industrial water system comprising the steps of: a) providing an industrial water system; b) adding to the water of that industrial water system i) a compound, wherein the compound is selected from the group consisting of alkali metal salts of chlorite and chlorate, or a mixture thereof; and ii) an acid; wherein the compound is added before the acid is added; and c) allowing water to circulate through the industrial water system for at least about one hour to about 72 hours; and d) drain the water from the industrial water system. The third aspect of the claimed invention
is an online method of simultaneous cleaning and disinfection of a water system comprising the steps of: a) providing an industrial water system; wherein the industrial water system is selected from the group consisting of cooling water systems and kettle water systems; b) optionally reduce the cycles of the industrial water system to simple cycles and interrupt the supply of chemical substances for routine water maintenance to the water of the industrial water system; c) adding a compound selected from the group consisting of the alkali metal salts of chlorite and chlorate, or a mixture thereof, and optionally adding corrosion inhibitor and optionally adding a dispersant to the water of that industrial water system; wherein sufficient compound is added to reach a concentration of about 1 ppm to about 1000 ppm; wherein if a corrosion inhibitor is added, sufficient corrosion inhibitor is added to reach a concentration of about 50 ppm to about 500 ppm and where a dispersant is added there is enough dispersant added to reach a concentration of about 1 ppm to about 500 ppm; d) decrease the pH of the water in the industrial water system to approximately 4.0 by adding an acid to the
water of the industrial water system and maintaining the pH of the water in the industrial water system at about 4.0 for about 1 to about 4 hours; e) adding a chelating agent to the water of the industrial water system, where sufficient chelating agent is added to maintain the concentration of the chelating agent from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein the chelating agent is added either before or after the next step of raising the pH; f) optionally raising the pH of the water of the industrial water system from about 5.5 to about 11 either by adding caustic soda or stopping the addition of acid or by a combination of both methods; g) add a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step of raising the pH, then the chelating agent and the biocide of step g) can be simultaneously added to the water or the chelating agent can be added first followed by the biocide or the biocide can be added. added first, followed by the chelating agent; wherein the amount of biocide added is that amount sufficient to have a concentration of about 1 ppm to about 500 ppm in the water of the water system
industrial; h) allowing the water in the industrial water system to circulate for an additional period of time from about 1 hour to about 120 hours; and i) complete the cleaning and disinfection method when the desired cleaning efficiency has been achieved; wherein, if the feed of the routine water treatment maintenance chemicals was stopped during the process, then the feeding of the routine water treatment chemicals into the water of the industrial water system is now resumed; and where, if the feed of the routine water treatment maintenance chemicals was not stopped during the process, then bring the industrial water system back to normal operation by stopping the supply of chemical cleaning substances, discharging the water for reduce system cycles to a single cycle, and then proceed under normal operating conditions. The fourth aspect of the claimed invention is: An online method of simultaneous cleaning and disinfection of an industrial water system comprising the steps of: a) providing an industrial water system; in which the industrial water system is selected from the group that
consists of cooling water systems and boiler water systems; b) optionally reduce the cycles of the industrial water system to simple cycles and interrupt the supply of chemical substances for routine water maintenance to the water of the industrial water system; c) add a chelating agent to the water of the industrial water system; wherein sufficient chelating agent is added to maintain the concentration of the chelating agent from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein the chelating agent is added before or after the next optional step of maintaining the pH; d) optionally maintaining the pH of the water in the industrial water system from about 5.5 to about 11 either by adding caustic soda or stopping the addition of acid or by a combination of both methods; e) add a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step to maintain the pH, then the chelating agent and the biocide of step e) can be added simultaneously to the water or the chelating agent can be added first followed by the biocide or the biocide can be added. added first, followed by the chelating agent; where the amount
of added biocide is that amount sufficient to have a concentration of about 1 ppm to about 500 ppm in the water of the industrial water system; f) allowing the water in the industrial water system to circulate for an additional period of time from about 1 hour to about 120 hours; and g) concluding the cleaning and disinfection method when the desired cleaning efficiency has been achieved; wherein, if the feed of the routine water treatment maintenance chemicals was stopped during the process, then the feeding of the routine water treatment chemicals into the water of the industrial water system is now resumed; and where, if the feed of the routine water treatment maintenance chemicals was not stopped during the process, then bring the industrial water system back to normal operation by stopping the supply of chemical cleaning substances, discharging the water for reduce system cycles to a single cycle, and then proceed under normal operating conditions. DETAILED DESCRIPTION OF THE INVENTION Throughout this patent application, the meaning of the following terms have been established:
"Fouling" refers to the deposit of any organic or inorganic material on a surface. These deposits prevent water from flowing and / or transferring heat, and house microorganisms that cause a greater deposit, enhance corrosion and increase health-related risks. "Cleaning" means reducing the overall amount of deposits, which is desirable because reducing the overall amount of deposits improves the overall efficiency of the industrial water system. "Disinfection" is typically used to describe a method for killing microorganisms. As used herein, the goal of disinfection is to cause a significant overall reduction in the number or viability of the microorganisms in the water system. "ONC" refers to Ondeo Nalco Company, Ondeo Nalco Center, 1601 W. Die l Road, Naperville, IL 60563, telephone (630) 305-1000. The first and second aspects of the present invention are a method of simultaneous cleaning and disinfection of an industrial water system comprising the steps of: a) providing an industrial water system; b) add to the water of that industrial water system i) a compound, selected from the group consisting of alkaline salts of chlorite and
chlorate, or a mixture thereof; and ii) an acid; and where the acid is added before the compound is added, or the acid is added after the compound is added; c) allowing water to circulate through the industrial water system for at least about one hour to about 72 hours; and d) drain the water from the industrial water system. The method of the present invention can be used to simultaneously clean and disinfect industrial water systems that are being installed, those that are currently in operation, that are temporarily not operating, or that have been inactive for long periods and are being restored for service. The claimed method of the present invention can be used to clean and disinfect many industrial water systems. These industrial water systems include, but are not limited to, cooling water systems, including open, closed and direct recirculation cooling water systems; kettles and boiler water systems; oil wells, well bottom formations, geothermal wells and other applications of the oil field; waters of mineral processes including mineral washing, flotation and donation; digesters of factories
paper, washing machines, blanching plants, supply containers, and white water systems, and surfaces of paper machines; evaporators of black liquors in the pulp industry; gas scrubbers and air washers; continuous processes of smelting in the metallurgical industry; air conditioning and refire systems; water from industrial processes and oil; cooling water and indirect contact heating, such as pasteurization water; water recovery systems, water purification systems; membrane filtration water systems; food processing streams (meat, vegetables, beets, sugar cane, grains, poultry, fruit and soybeans); and waste treatment systems as well as clarifiers, liquid-solid applications, municipal wastewater treatment, municipal water system, potable water systems, aquifers, water tanks, spray systems and water heaters. Preferred industrial water systems for simultaneous cleaning and disinfection by the method of the claimed invention are cooling water systems, including open, closed and direct recirculating cooling water systems, paper machine surfaces, water treatment streams food, waste treatment systems and drinking water systems. The most preferred industrial water systems for cleaning
and disinfecting simultaneously by the method of the present invention are cooling water systems, including open, closed and direct recirculating cooling water systems. Before carrying out the claimed method of the present invention, it is typically recommended, but not required, that the addition to the water of any chemical or biological treatment substance be discontinued. It is also recommended to stop any transfer of energy in the system in such a way that before the addition of the compound and acid, the water of the industrial water system is recirculated through the industrial water system without being chemically or biologically treated and without having occurred heat transfer. The compound is selected from the alkali metal salts of chlorite and chlorate and mixtures thereof. These alkaline salts include sodium chlorite, potassium chlorite, sodium chlorate and potassium chlorate. The preferred alkaline salts are sodium chlorite and sodium chlorate. The most preferred alkaline salt is sodium chlorite. The alkali salts of chlorite and chlorate are bulk chemicals that can be obtained from most chemical distribution companies. Sodium chlorite can be obtained at its normal pH or in its "stabilized form" as it is colloquially called at a pH
high. The preferred sodium chlorite is a 25% solution of sodium chlorite in water. This material is available as ONC HYG-25. Sodium chlorate is a bulk chemical that can be obtained from most chemical distribution companies. The preferred sodium chlorate is from about 20 to about 50% w / w of sodium chlorate solution in water. This preferred sodium chlorate is available from Eka Chemicals, Inc., 1775 West Oak Commons Court, Marietta, GA 30062-2254 USA, telephone number 1-770-578-0858. Both potassium chlorite and potassium chlorate are available from most chemical distribution companies. The amount of sodium chlorite or potassium chlorite added to the water in the industrial water system depends on what type of industrial water system is to be cleaned and disinfected. If the method of the present invention is applied to a cooling water system, then the amount of sodium chlorite or potassium chlorite added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm and with more preferably from about 50 ppm to about 250 ppm. The amount of sodium chlorate or potassium chlorate
added to the water of the industrial water system depends on what type of industrial water system will be cleaned and disinfected. If the method of the present invention is applied to a cooling water system, then the amount of sodium chlorate or potassium chlorate added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm and more preferably from about 50 ppm to about 250 ppm. If the sodium chlorite or potassium chlorite and the sodium chlorate or potassium chlorate are both used then the ratio of chlorite or chlorate, expressed in percent-by weight, is from about 1:99 to about 99: 1, preferably from about 10:90 to about 90:10, and more preferably about 50:50. The total amount of both chlorite and chlorate together is the same as for chlorite or chlorate alone. The acid is selected from the group consisting of mineral acids and organic acids wherein the mineral acids are selected from the group consisting of hydrochloric acid, sulfuric acid, sulfuric acid (98%), nitric acid, phosphoric acid, hydrofluoric acid and acid. sulfamic; and the organic acids are selected from the group consisting of citric acid and its salts, formic acid, acetic acid, peracids including peracetic acid, peroxyacetic acid and
peroxiformic acid, glycolic acid (hydroxyacetic acid), oxalic acid, propionic acid, lactic acid (hydroxypropionic acid) and butyric acid. The choice of acid depends mainly on the metallurgy of the system. For metals such as carbon steel, copper, or yellow metal alloys the preferred acids are hydrochloric acid, sulfamic acid, formic acid and glycolic acid. The most preferred acid, for most metals, is hydrochloric acid. These acids are commercial chemicals available from a chemical distribution company. These acids can be purchased in dry or liquid form or in formulations containing other functional chemicals which can also be in dry or liquid form. For example, most of these acids can be obtained in formulation with corrosion inhibitors. Hydrochloric acid formulated with a corrosion inhibitor made of diethyl urea is sold as ONC Nalco®2560 Inhibited HC1. The amount of acid added to the water in the industrial water system depends on the type of industrial water system to be cleaned and disinfected. If the method of the present invention is applied to a cooling water system, then the amount of acid added is that which is required to achieve and maintain a pH of
about 1 to about 5, preferably from about 1 to about 3 and more preferably from about 2 to about 2.5. People with ordinary skill in the art know how to calculate how much of each acid would be required in order to achieve the desired pH taking into account the volume of the system and the alkalinity in the system. The compound selected from the group consisting of alkali salts of chlorite and chlorate and mixtures thereof and the acid are added directly to the water of the industrial water system, without premixing before addition. Either way, the acid is added before the compound or compound is added before the acid. It is possible, although not preferred, to add the acid and the compound simultaneously to the water. The advantage of the present claimed method is that it is possible to obtain continuous generation of chlorine dioxide disinfectant through the water system while simultaneously cleaning the acid. The addition of the compound and the acid separately allows a certain amount of compound and acid circulation prior to its reaction to create chlorine dioxide. This means that more chlorine dioxide is created beyond the point of addition of the compound and the acid. After the compound and the acid are added to the
water, the water lets circulate through the industrial water system. This circulation of water allows the cleaning and disinfection of the "water contact" surfaces of the equipment in the industrial water system. In addition to cleaning and disinfecting water contact surfaces, volatile chlorine dioxide is also able to reach surfaces that are not continuously in contact with water. The water in the industrial water system is allowed to circulate for a period of time from about 1 hour to about 72 hours, preferably from about 1 hour to about 24 hours and more preferably from about 1 hour to about 8 hours. During these periods of time it is possible, although not required, to monitor the progress of the cleaning and (indirectly monitor) the disinfection using standard techniques to determine the amount of ions present in the water for the rupture and the takeoff of the inorganic deposits. Inorganic deposits are typically calcium salts, magnesium salts, iron salts, copper oxide and manganese salts. For example, it is known that it is typical that the amount of calcium ion in the water rises continuously as cleaning proceeds and the scale, known to contain calcium, is removed from the surfaces
of the team. When the amount of calcium in the plateaus of water indicates that the cleanup is complete it is because no more calcium scaling dissolves. After the cleaning and disinfection ends, the water in the industrial water system must be drained and sent to appropriate treatment in such a way that it can be discharged in compliance with state or local regulations. Of course, once the water is drained, it will be necessary to carry out additional mechanical cleaning of the water contact surfaces. This mechanical cleaning is recommended when cleaning and disinfecting has worked so well that there is a buildup of loose dirt and other undesirable material collected in the corners and crevices of the industrial water system. These corners and crevices may include the filler used in most cooling towers. After the mechanical cleaning is finished, it is possible to fill with water and start the operation of the industrial water system. For highly contaminated industrial water systems it is also possible to fill the industrial water system with water and carry out again the method of the claimed invention. In addition to the named chemicals, it is possible to carry out the claimed method of the present invention by adding additional functional chemicals. These additional functional chemicals include biocides,
corrosion inhibitors, dispersants, surfactants, reducing agents and chemical products added for pH adjustment. Additional biocides can be added when microbial contamination is severe. Suitable biocides for use in the claimed invention are selected from the group consisting of oxidizing or non-oxidizing biocides. Oxidizing biocides include, but are not limited to, chlorine bleach, chlorine, bromine and materials capable of liberating chlorine and bromine. The preferred oxidant biocide is chlorine bleach. Non-oxidizing biocides include, but are not limited to, glutaraldehyde, isothiazoline, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3-diol, 1-bromo-1- (bromomethyl) - 1,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyl dimethyl benzyl ammonium chloride, dimethyl dialkyl ammonium chloride, didecyldimethyl ammonium chloride, poly (oxyethylene (dimethyliminium) ethylene (dimethyliminium) ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, sulphate of tetraki shidr or ime ti 1 phosphonium, dithiocarb ama to, ci nodit ioimidocarbonate, 2-methyl-5-nitroimidazol-l-ethanol, 2- (2-bromo-2-nitroetenyl) furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomemethylglutaronitrile, bis (trichloromethyl) sulphone, t-Iometanosul fonate of S- (2-hydroxypropyl), tetrahydro-3, 5-
dimethyl-2H-l, 3, 5-hydraz ina-2-1-ion, 2- (thiocyanomethylthio) benzothiazole, 2-bromo- '-hydroxyacetyone, 1,4-bis (bromoacetoxy) -2-butene, oxide of bis (tributyltin), 2- (tert-butylamino) -4-chloro-6- (ethylamino) -s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coconut oxide alkyldimethylamine, n-coconut alkyltrimethylenediamine, tetrachloride alkyl phosphonium, 7-oxabicyclo [2.2.1] eptane-2,3-decarboxylic acid, 4,5-dichloro-2n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin- 3-one and 2-methyl-4-isothiazolin-3-one. The preferred non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide and is available from ONC. If the method of the present invention is applied to a cooling water system, then the amount of oxidant biocide added is from about 0.1 ppm to about 200 ppm, preferably from about 1 ppm to about 100 ppm, more preferably about 5 ppm. at about 50 ppm and more preferably from about 5 ppm to about 20 ppm. The corrosion inhibitors can be added when it is necessary to reduce the corrosion of the metal in the industrial water system. Corrosion inhibitors for protection of multiple metals are typically triazoles, such as, but not limited to, benzotriazole, halogenated triazoles,
nitro-substituted azoles, and other triazoles as listed in U.S. Patent No. 5,874,026, which is incorporated herein by reference in its entirety. The preferred triazole is benzotriazole. Triazoles are commercially available from most chemical distribution companies. The preferred benzotriazole is Nalco® 73199, which is available from Ondeo Nalco Company. Whether a corrosion inhibitor is used depends on the industrial water system and the composition of the contact surfaces of the water in the industrial water system. For example, if all the contact surfaces of the water in the industrial water system are wood, precious metals, glass, titanium or plastic, then the use of corrosion inhibitor in those systems is not recommended. However, when the water contact surfaces are metals without titanium, such as, but not limited to, stainless steel, carbon steel, galvanized steel, and yellow metals such as copper, admiralty and brass, then the use of a corrosion inhibitor. The amount of corrosion inhibitor added to the water of the industrial water system depends on what type of industrial water system will be cleaned and disinfected. If the claimed method of the present invention is applied to a cooling water system, then the amount of
The added corrosion inhibitor is from about 1 ppm to about 2000 ppm, preferably from about 10 ppm to about 1000 ppm and more preferably from about 50 ppm to about 600 ppm. The corrosion inhibitor should be added before, after or during the addition of the compound to the acid. The corrosion inhibitor is preferably added before the addition of acid. The corrosion inhibitor can be added immediately before adding the acid and the compound. However, it is preferred that the corrosion inhibitor be added sufficiently before the acid addition in such a way that the corrosion inhibitor can circulate through the system. It is therefore preferred that the corrosion inhibitor be added from about 1 hour to about 24 hours before the addition of the compound and the acid. The corrosion inhibitor could also be formulated previously with other ingredients that are added to water. As mentioned above, the corrosion inhibitor can be formulated with acid to create an "inhibited acid". Dispersants are added when it is necessary to keep particulate matter present in the water of a dispersed industrial water system, so that it does not agglomerate and cause fouling during the process of
cleaning and disinfection. Dispersants are typically low molecular weight anionic polymers, "low" refers to a weight average molecular weight of from about 500 to about 20,000. These polymers are typically, but not limited to, acrylic acid, polymaleic acid, copolymers of acrylic acid with sulfonated monomers and their alkyl esters. These polymers can include terpolymers of acrylic acid, acrylamide and sulfonated monomers. These polymers may also include tetrapolymers consisting of acrylic acid and three other monomers. Dispersing polymers are commercially available from most chemical distribution companies. The preferred dispersant polymer is a high stress polymer such as PR 4832 High Stress Polymer which is available from Ondeo Nalco Company. The use of a dispersant depends on the industrial water system, on the deposits present in the system and on the pollutants present in the water and the composition of the contact surfaces of the water in the industrial water system. The amount of dispersant added to the water of the industrial water system depends on what type of industrial water system is to be cleaned and disinfected. If the method
of the present claimed invention is applied to a cooling water system then the amount of dispersant that is added is from about 1 ppm to about 500 ppm, preferably from about 5 ppm to about 200 ppm and more preferably about 10 ppm to approximately 100 ppm. The dispersant can be added be, after or during the addition of the compound and the acid. The dispersant could be formulated previously with other ingredients that are added to the water. One or more surfactants can be added when and where needed to improve the cleaning and disinfection process. Surfactants useful in industrial water systems include, but are not limited to, ethylene oxide propylene oxide copolymers, linear alkylbenzene sulfonates ("LAS"), ethoxylated phosphate esters, and alkyl polyglycosides, and other surfactants described in US Patent No. 6,139,830, US Patent No. 5,670,055 and US Patent No. 6,080,323, all of which are incorporated by reference. Surfactants are commercially available from most chemical distribution companies. Preferred surfactants are copolymers of ethylene oxide, propylene oxide and alkyl polyglycosides.
These surfactants CL-103, CL-361, CL-362, Nalco © 73550 and Nalco © 7348 are available from ONC. If a surfactant is used, it depends on the industrial water system, the tanks or soiling agents, and the composition of the contact surfaces of the water in the industrial water system. The amount of surfactant added to the water in the industrial water system depends on the type of industrial water system to be cleaned and disinfected. If the method of the present invention is applied to a cooling water system, then the amount of surfactant that is added is from about 0.1 to about 1000 ppm, preferably from about 1 ppm to about 500 ppiti and more preferably about 5 ppm to approximately 100 ppm. Surfactant may be added at any time during the simultaneous cleaning and disinfecting method, but the surfactant will preferably be added after the generation of chlorine dioxide has begun (in order to reduce any potential aerosol formation of viable microbial foulers). One or more reducing agents can be added when and where needed to react with present oxidants in order to prepare the water for discharge in compliance with state and local environmental regulations. The agents
Reducers suitable for use in the claimed method of the present invention include, but are not limited to, sodium thiosulfate, sodium bisulfite, sodium metabisulphite and sodium sulfite. Reducing agents are commercially available from most chemical distribution companies. The preferred reducing agent is sodium bisulfite which is available from Ondeo Nalco Company. If a reducing agent is used, this depends on the industrial water system and the amount of oxidants present there. The amount of reducing agent added to the water of the industrial water system depends on the type of industrial water system to be cleaned and disinfected. If the method of the present invention is applied to a cooling water system, then the amount of reducing agent that is added is equimolar to the amount of oxidant present. Another way to determine the amount of reducing agent that is required is to add a reducing agent until there is no residual halogen present. The reducing agent is typically added at the end of the cleaning and disinfection process just before the water is discharged or can be added to the discharge pipe or tank. A chemical can be added to adjust the pH when it is necessary to adjust the pH of the water that is discharged
of the industrial water system. Typical substances for pH adjustment include, but are not limited to, NaOH (also known as "caustic soda"), KOH, Ca (OH) :, Na; C03 and K2C03. The preferred chemical for pH adjustment is caustic soda, specifically a 50% solution of NaOH in water. Caustic soda is commercially available from most chemical distribution companies. The amount of chemical for pH adjustment added to the water of the industrial water system depends on the type of industrial water system to be cleaned and disinfected, the pH that water typically has, and what the pH requirements for water are that will be discharged from the industrial water system. If the claimed method of the present invention is applied to a cooling water system, then the amount of chemical substance added for pH adjustment is that which is required to achieve a pH of from about 2 to about 8, preferably from about 3 to about 7 and more preferably about 4 to about 6. The pH adjusting chemical is typically added at the end of the cleaning and disinfection process just before the water is discharged or can be added to the discharge pipe or the tank .
In the practice of the claimed method of the present invention all chemical substances can be added separately. Apart from the compound and the acid that are added separately, the other chemicals can be formulated together. A preferred formulation would include corrosion inhibitor, dispersant and surfactant mixed together in a single product. At the end of the process, the water containing the cleaning and disinfection chemicals and waste material removed from the water is drained from the industrial water system. Then, the system can be re-filled with water and returned to service immediately or not, depending on the needs of the system operators. Of course it is possible to fill the tower with fresh water and carry out the claimed method of the present invention again, in order to clean highly contaminated industrial water systems. If a cooling tower has been cleaned and disinfected by the method of the claimed invention, any of the following actions can take place at the end of the method. 1) fill the cooling tower using fresh replacement water, and start dosing a "normal" treatment program of inhibitors and biocides;
2) fill the tower using fresh replacement water, and begin dosing a program of inhibitors and / or biocides at high doses, to achieve passivation of any exposed metal and kill any remaining organisms, followed by the resumption of a treatment program "normal"; 3) allow the cooling tower to dry for a period in which cooling is not required; or fill the system with fresh replacement water, and discharge doses of inhibitors and / or biocide in high doses, then drain the system (without having never continued with the normal function) and let it dry for a period in which cooling is not required . 4) Fill the cooling tower with fresh replacement water, drain the system and refill, dispense doses of inhibitors and / or biocide at high or normal doses, then resume service. The advantages of the first and second aspects of the claimed invention include the fact that this cleaning and disinfecting process removes deposits from virtually all surfaces that can get wet, and simultaneously disinfects water in large volume and all surfaces that can get wet, and some surfaces that are not continuously in contact with water, by means of in-situ CIO generation? · The method of the claimed invention is designed to minimize the
corrosion at the same time that cleaning and disinfection takes place, can be completed in less than eight hours, effectively removes microbial deposits and significantly extends the period of microbial recolonization. The procedure works to clean industrially heavily soiled water systems well enough. The third aspect of the claimed invention is an online method of simultaneous cleaning and disinfection of an industrial water system comprising the steps of: a) providing an industrial water system; wherein the industrial water system is selected from the group consisting of cooling water systems and kettle water systems; b) optionally reduce the cycles of the industrial water system to simple cycles and interrupt the supply of chemical substances for routine water maintenance to the water of the industrial water system; c) adding a compound selected from the group consisting of the alkali metal salts of chlorite and chlorate, or a mixture thereof, and optionally adding corrosion inhibitor and optionally adding a dispersant to the water of that industrial water system; wherein sufficient compound is added to reach a concentration of about 1 ppm to about 1000 ppm; where if a corrosion inhibitor is added, enough is added
corrosion inhibitor to reach a concentration of about 50 ppm to about 500 ppm and wherein if a dispersant is added there is added sufficient dispersant to reach a concentration of about 1 ppm to about 500 ppm; d) lowering the pH of the water in the industrial water system to about 4.0 by adding an acid to the water of that industrial water system and maintaining the pH of the water in the industrial water system at about 4.0 for about 1 to about 4 hours; e) adding a chelating agent to the water of the industrial water system, where sufficient chelating agent is added to maintain the concentration of the chelating agent from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein the chelating agent is added either before or after the next step of raising the pH; f) optionally raising the pH of the water of the industrial water system from about 5.5 to about 11 either by adding caustic soda or stopping the addition of acid or by a combination of both methods; g) add a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step of raising the pH, then the
chelating agent and biocide from step g) can be added simultaneously to the water or the chelating agent can be added first followed by the biocide or the biocide can be added first, followed by the chelating agent; wherein the amount of biocide added is that amount sufficient to have a concentration of about 1 ppm to about 500 ppm in the water of the industrial water system; h) allowing the water in the industrial water system to circulate for an additional period of time from about 1 hour to about 120 hours; and i) completing the cleaning and disinfection method when the desired cleaning efficiency has been achieved; wherein, if the feed of the routine water treatment maintenance chemicals was stopped during the process, then the feeding of the routine water treatment chemicals into the water of the industrial water system is now resumed; and where, if the feed of the routine water treatment maintenance chemicals was not stopped during the process, then bring the industrial water system back to normal operation by stopping the supply of chemical cleaning substances, discharging the water for reduce system cycles to a single cycle, and then proceed under operating conditions
normal The third aspect of the claimed invention is a method applicable to cooling water systems and boiler water systems. These industrial water systems consist of evaporative cooling towers, cooling water systems of open, closed and direct recirculation; boilers and boiler water systems and industrial water systems including cooling water equipment and boiler equipment. The compound is selected from the alkali metal salts of chlorite and chlorate and mixtures thereof. These alkaline salts include sodium chlorite, potassium chlorite, sodium chlorate and potassium chlorate. The preferred alkaline salts are sodium chlorite and sodium chlorate. The most preferred alkaline salt is sodium chlorite. The alkali salts of chlorite and chlorate are bulk chemicals that can be obtained from most chemical distribution companies. Sodium chlorite can be obtained at its normal pH or in its "stabilized form" as it is colloquially called at high pH. The preferred sodium chlorite is a 25% solution of sodium chlorite in water. This material is available as ONC HYG-25. Sodium chlorate in a bulk chemical that
It can be obtained from most of the chemical distribution companies. The preferred sodium chlorate is from about 20 to about 50% w / w of sodium chlorate solution in water. This preferred sodium chlorate is available from Eka Chemicals, Inc., 1775 West Oak Commons Court, Marietta, GA 30062-2254 USA, telephone number 1-770-578-0858. Both potassium chlorite and potassium chlorate are available from most chemical distribution companies. The amount of sodium chlorite or potassium chlorite added to the water in the industrial water system depends on what type of industrial water system is to be cleaned and disinfected. If the claimed method of the present invention is applied to a cooling water system, then the amount of sodium chlorite or potassium chlorite added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm. and more preferably from about 50 ppm to about 250 ppm, and much more preferably from about 100 ppm. If the sodium chlorite or potassium chlorite and the sodium chlorate or potassium chlorate are both used then the ratio of chlorite or chlorate, expressed in percent by weight, is from about 1:99 to about 99: 1,
preferably from about 10:90 to about 90:10, and more preferably about 50:50. The total amount of both chlorite and chlorate together is the same as for chlorite or chlorate alone. The corrosion inhibitor optionally used in the third aspect of the claimed invention is selected from the group consisting of benzotriazole, halogenated triazoles, nitro-substituted azoles, and the trazoles listed in U.S. Patent No. 5,874,026, which is incorporated by reference In its whole. The preferred triazole is benzotriazole. Benzotriazole is available from ONC as Nalco 73199. The amount of azole added is sufficient to reach a concentration of about 50 to about 500 ppm in the water of the industrial water system. The preferred concentration of azole is about 100 ppm in the water of the industrial water system. The dispersant optionally used in the third aspect of the claimed invention is selected from the group consisting of, but not limited to, high stress polymer (as described above), acrylic acid, polymaleic acid, copolymers of acrylic acid with sulphonated monomers and their alkyl esters. These polymeric dispersants can include terpolymers of acrylic acid, acrylamide and sulfonated monomers. These
Polymer dispersants may also include tetrapolymers consisting of acrylic acid and three other monomers. The preferred dispersant is a terpolymer comprising from about 30 to 70 mol% acrylic acid, from about 10 to 30 mol% acrylamide and from about 20 to 40% aminoethylsulfonic acid. A terpolymer with such a composition is available from ONC as PR 4832 High Stress Polymer. The amount of dispersant added is sufficient to reach a concentration of about 1 ppm to about 500 ppm. The preferred amount of dispersant is about 100 ppm. The acid used in the third aspect of the claimed invention is either a mineral acid or organic acid selected from the group consisting of hydrochloric acid, sulfuric acid, sulfuric acid (98%), nitric acid, phosphoric acid, hydrofluoric acid and sulfamic acid; and the organic acids are selected from the group consisting of citric acid and its salts, formic acid, acetic acid, peracids including peracetic acid, peroxyacetic acid and peroxy formic acid, glycolic acid (hydroxyacetic acid), oxalic acid, propionic acid, lactic acid ( hydroxypropionic acid) and butyric acid. The preferred acid is glycolic acid, which is available as Nalco R3076 from ONC. The amount of acid added is the
sufficient amount to lower the pH of the water to about 4.0 and to subsequently maintain the pH at about 4.0. The chelating agent useful in the third aspect of the claimed invention is selected from the group consisting of sodium hexametaphosphate, sodium polyphosphate, phosphonates, and polycarboxylates (homopolymers and copolymers). The preferred chelating agent is sodium hexametaphosphate. It is available as Glassy Calgon from ONC. Sufficient chelating agent is added such that the concentration of the chelating agent is from about 10 ppm to about 500 ppm in the water of the industrial water system. The biocide useful in the third aspect of the claimed invention can be an oxidant biocide or a non-oxidizing biocide. The oxidizing biocides are selected from the group consisting of chlorine bleach, chlorine, bromine and materials capable of liberating chlorine and bromine. The preferred oxidant biocide is chlorine bleach. The non-oxidizing biocides are selected from the group consisting of g 1 utara 1 of hi do, isothiazo 1 ina, 2, 2-dibrino-3-nitrilopropionamide, 2-bromo-2-ni tropropane-1,3 diol, 1- bromine-1- (bromomethyl) -1,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyl dimethyl benzyl ammonium chloride, dimethyl dialkyl ammonium chloride,
1-dimethyl ammonium dichloride, poly (oxyethylene (dimethyliminium) ethylene (dimethyliminium) ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbonate, cyanodi thioimidocarbonate, 2-methyl-5-nitroimidazole- l-ethanol, 2- (2-boron-2-nitr oe t eni 1) furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene, beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis ( trichloromethyl) sulfone, S- (2-hydroxypropyl) thiomethanesulfonate, tetrahydro-3,5-dimethyl-2H-1, 3,5-hydrazine-2-thione, 2- (thiocyanomethylthio) benzothiazole, 2-bromo-4 '- hydroxyacetofenone, 1,4-bis (bromoacetoxy) -2-butene, bis (tributyltin) oxide, 2- (tert-butylamino) -4-chloro-6- (ethylamino) -s-triazine, dodecylguanidine acetate, hydrochloride of dodecylguanidine, coconut oxide alkyldimethylamine, n-coconut alkyltrimethylenediamine, tetra-alkyl phosphonium chloride, 7-oxabicyclo [2.2.1] heptane-2, 3-decarboxylic acid, 4, 5-dichloro-2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-l-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. The preferred non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide, which is available as Nalco N7649 from ONC. The amount of biocide added is the amount sufficient to have a concentration of about 1 ppm to about 20 ppm in the water of the industrial water system. In the third aspect of the present invention
claimed, the online method of cleaning and disinfection of industrial water systems allows the cleaning of organic and inorganic deposits initially through the decrease of pH, using an acid for a short period of time and subsequently for a prolonged period of time using a chelating agent at a pH close to neutral. Disinfection takes place initially through the in situ generation of chlorine dioxide when the pH is about 4.0, followed by the addition of a chelating agent and a biocide when the pH is close to a neutral value. The fourth aspect of the claimed invention is: An online method of simultaneous cleaning and disinfection of an industrial water system comprising the steps of: a) providing an industrial water system; wherein the industrial water system is selected from the group consisting of cooling water systems and kettle water systems; b) optionally reduce the cycles of the industrial water system to simple cycles and interrupt the supply of chemical substances for routine water maintenance to the water of the industrial water system; c) add a chelating agent to the water of the industrial water system; in which enough agent is added
chelating agent to maintain the concentration of the chelating agent from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein the chelating agent is added before or after the next optional step of maintaining the pH; d) optionally maintaining the pH of the water in the industrial water system from about 5.5 to about 11 either by adding caustic soda or stopping the addition of acid or by a combination of both methods; e) add a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step to maintain the pH, then the chelating agent and the biocide of step e) can be added simultaneously to the water or the chelating agent can be added first followed by the biocide or the biocide can be added. added first, followed by the chelating agent; wherein the amount of biocide added is that amount sufficient to have a concentration of about 1 ppm to about 500 ppm in the water of the industrial water system; f) allowing the water in the industrial water system to circulate for an additional period of time from about 1 hour to about 120 hours; and g) conclude the cleaning and disinfection method when
the desired cleaning efficiency has been achieved; wherein, if the feed of the routine water treatment maintenance chemicals was stopped during the process, then the feeding of the routine water treatment chemicals into the water of the industrial water system is now resumed; and where, if the feed of the routine water treatment maintenance chemicals was not stopped during the process, then bring the industrial water system back to normal operation by stopping the supply of chemical cleaning substances, discharging the water for reduce system cycles to a single cycle, and then proceed under normal operating conditions. In the fourth aspect of the claimed invention, cleaning is attributed to chelation by the chelating agent and disinfection occurs as a function of the added biocide. The chelating agent useful in the fourth aspect of the claimed invention is selected from the group consisting of sodium hexametaphosphate, sodium polyphosphate, phosphonates, and polycarboxylates (homopolymers and copolymers). The preferred chelating agent is sodium hexametaphosphate. It is available as Glassy Calgon from ONC. Enough chelating agent is added in such a way that the concentration
of the chelating agent is from about 10 ppm to about 500 ppm in the water of the industrial water system. The biocide useful in the fourth aspect of the claimed invention can be an oxidant biocide or a non-oxidizing biocide. Oxidizing biocides are selected from the group consisting of chlorine bleach, chlorine, bromine and materials capable of releasing chlorine and bromine. The preferred oxidant biocide is chlorine bleach. The non-oxidizing biocides are selected from the group consisting of glutaraldehyde, isothiazoline, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3-diol, 1-bromo-1- (bromomethyl) -1 , 3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyl dimethyl benzyl ammonium chloride, dimethyl dialkyl ammonium chloride, didecyldimethyl ammonium chloride, poly (oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, sulfate idr tetrakish ox ime ti 1 phosphonium ditiocarb love to, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-l-ethanol, 2- (2-bromo-2-nitroethenyl) furan, beta-bromo-beta-nitrostyrene, beta-nitrostyrene , beta-nitrovinyl furan, 2-bromo-2-bromomethyl glutaronitrile, bis (trichloromethyl) sulfone, S- (2-hydroxypropyl) thiomethanesulfonate, tetrahydro-3, 5-dimet and 1-2H-1, 3, 5-hydraz ina-2 - 1 ione, 2- (thiocyanomethylthio)
benzothiazole, 2 -brorno - 4 '- hi dr ox iacetof enone, 1,4-bis (bromoacetoxy) -2-butene, bis (tributyltin), 2- (tert-butylamino) -4-chloro-6- ( ethylamino) -s-triazine, dodecylguanidine acetate, dodecylguanidine hydrochloride, coconut alkyldimethylamine oxide, n-coco alkyltrimethylenediamine, tetra-alkyl phosphonium of chloride, 7-oxabicyclo acid [2.2.1] heptane-2, 3-decarboxilico, 4 , 5-dichloro-2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isot iazolin-3-one. The preferred non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide, which is available as Nalco N7649 from ONC. The amount of biocide added is the amount sufficient to have a concentration of about 1 ppm to about 20 ppm in the water of the industrial water system. EXAMPLES The following examples are presented in illustrative form of the present invention and for teaching someone with normal experience how to make and use the invention. These examples are not intended to limit the invention or its protection in any way. Example 1 A pilot tower plastic with metal cooling exchangers titanium and a plastic collector are chosen as the test site for the method of the second aspect of the present claimed invention. The
Pilot cooling tower is almost in continuous use for more than a year for which there is severe contamination present. It is believed that the contamination is as much of inorganic incrustations as of adhering microbiolol populations. There is a visible soiling on most water contact surfaces as well as particles of visible material in the water that is circulating. In order to carry out the claimed method of the present invention it is necessary to leave the pilot cooling tower out of service for 24 hours. To prepare the cleaning and disinfection of the pilot cooling tower, the heat load of the cooling system is removed. Cooling system fans turn off and the purge valve closes. adding the chemicals, such water treatment program that the water flowing through the cooling tower has only pilot chemicals from waste water treatment is discontinued. Throughout the cleaning and disinfection program, the water recirculation of the pilot cooling tower is activated. The benzotriazole and the dispersant, which is a high-stress polymer PR 4832 of ONC, are added to the water in the pilot cooling tower. HE
add enough benzotriazole to reach a concentration of approximately 100 ppm. Sufficient stress polymer is added to reach a concentration of approximately 100 ppm. Sodium chlorite (NaC102), taken from the chemical product store, is added to the system water in such a way that its concentration in the water is 100 ppm. Sodium chlorite is circulated in the system for 30 minutes. After adding inhibited hydrochloric acid to the water. Sufficient hydrochloric acid is added in such a way that the pH of the water is from about 2.0 to about 3.0, preferably about 2.5. The water is circulated for 6 hours while continuing the addition of any amount of acid that is required in order to maintain a pH of about 2.0 to about 2.5. During cleaning and disinfection, samples were collected periodically and chlorine dioxide is monitored using a standard analytical technique to determine chlorine dioxide (such as the test of diethyl-p-phenylamine ( "DPD test") for dioxide free residual chlorine, expressed "as chlorine") as well as determining the level of hardness present by complete ommetric titration. During this six-hour time period, it is found that chlorine dioxide concentrations are
in the range of about 0.5 to about 1.0 ppm, expressed as free chlorine. The hardness values increase from 600 to 2000 ppm during a period of 5 hours. After 5 hours, the increases in the hardness value are minimal and the addition of acid is stopped. The system water is recirculated for an additional hour. The system is drained. The system is flushed with fresh replacement water and drained a second time. A visual inspection of the contact surfaces of the water shows surfaces without contamination. The simultaneous cleaning and disinfection method is considered a success. After the second drain, the pilot cooling tower is filled with fresh replacement water and returned to normal service. Example 2 This is an example of the third aspect of the claimed invention. A plastic pilot cooling tower with titanium metal exchangers and a plastic manifold are chosen as the test site for the method of the third aspect of the claimed invention. The pilot cooling tower is almost in continuous use so there is severe contamination present. It is believed that the contamination is as much of inorganic incrustations as of adhering microbiological populations. There is a fouling
visible on most water contact surfaces as well as visible matter particles in the water that is circulating. To prepare the cleaning and disinfection of the pilot cooling tower, the water in the cooling system is purged to reduce the water in the system to a simple cycle. The heat load and the fans of the cooling system remain in operation. For this example, the addition of chemical substances from the water treatment program is discontinued, so that the water circulating through the pilot cooling tower presents only chemical waste water treatment chemicals. Throughout the cleaning and disinfection program, the water recirculation of the pilot cooling tower is activated. The benzotriazole and the dispersant, which is a high-stress polymer PR 4832 of ONC, are added to the water in the pilot cooling tower. Sufficient benzotriazole is added to reach a concentration of approximately 100 ppm. Sufficient stress polymer is added to reach a concentration of approximately 100 ppm. Sodium chlorite (NaC102) is added, taken from the chemical product store, to the system water in such a way that its concentration in the water is 100 ppm. Sodium chlorite is circulated in the system for 30
minutes Then glycolic acid is added to the water. Sufficient glycolic acid is added in such a way that the pH of the water is from about 3.5 to about 5.5, preferably about 4.0. The water is circulated for about 1.0 to about 4.0 hours, preferably about 2.0, while continuing the addition of any amount of acid that is required in order to maintain a pH of about 4.0 to about 4.25. During cleaning and disinfection, samples are collected periodically and chlorine dioxide is monitored using a standard analytical technique to determine chlorine dioxide (such as the diethyl-p-phenylamine test ("DPD test") for dioxide. free residual chlorine, expressed "as chlorine") as well as determining the level of hardness present by complete ommetric titration. During this two-hour time period, it is found that chlorine dioxide concentrations are in the range of about 0.5 to about 1.0 ppm, expressed as free chlorine. The hardness values increase from 400 to 1600 ppm during a period of 2 hours. After 2 hours the acid feed is stopped. The system water is recirculated for an additional hour and the pH of the system water is allowed to rise due to increased alkalinity in the system. It also reaches a fast
raising the pH by the addition of sufficient caustic soda solution to bring the pH from about 5.0 to 6.5, preferably to 5.5. Sufficient sodium hexametaphosphate, used as a chelating agent, taken from the Ondeo Nalco chemical product store, is added to the system water in such a way that its concentration in the water is from about 10 ppm to about 500 ppm, preferably 200 ppm. A sufficient amount of a 2, 2-dibromo-3-nitrilopropionamide non-oxidizing biocide, taken from the Ondeo Nalco chemical product store, is added to the system water, such that its concentration in the water is from about 1 ppm to about 20 ppm. ppm. The pH of the system water is maintained at 5.5 with intermittent addition of glycolic acid as needed. The purge of the water from the system was maintained for the normal operational program and the losses of chemical substances (hexametaf os of sodium and 2, 2-dibrino-3-nitrilopropionamide) after purging were replenished by means of discharges of the chemical substances. The water in the system was recirculated for a period of approximately 48 hours. The total hardness levels were periodically monitored and when the increases in hardness level are minimal, the acid and biocide feed is stopped and the cleaning process is considered complete. The water of
The system is purged until it has simple cycles, and the routine water treatment program is reinstalled. The industrial water system is returned to normal service. A visual inspection of the contact surfaces of the water shows surfaces without contamination. The method of simultaneous cleaning and disinfection online is considered a success. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.