CZ20001131A3 - Water treatment process and apparatus for making the same - Google Patents

Abstract

The method of treating aqueous media involves exposure to aqueous media media in an electrolytic cell (1) electrical direct current of such magnitude and such fluid flow through said electrolytic cell in order to the combined boiler removal effect was achieved stone and disinfectant effect.

Description

The present invention relates to water treatment systems, in particular scaling-removing water treatment systems, and biocidal water treatment systems.

BACKGROUND OF THE INVENTION

The problem of scaling is inherent in all systems in which water flows containing ICI some of ions Ca ²⁺ and Mg ^2+, along with some of the ions OH-, CO3 ² ', HCO3-, SiO ₃ ^2- or SO ₄ ^2-. At a certain temperature and pH, carbonates, silicates, sulphates and hydroxides can precipitate causing nozzle blockage, reduced pipe cross-sectional area, thermal insulation, and corrosion can occur under deposits. Known methods for scaling from aqueous liquids are reverse osmosis and ion exchange. Another method for scaling is direct current electrolysis (DC). US 4,384,943 discloses a method of treating a fluid which comprises applying a DC stream to aqueous liquids.

Electrolytic treatment of aqueous fluids to form biocides is known in the art. For example, U.S. Pat. No. 4,384,943 discloses such a treatment which comprises adding a compound that is electrochemically degradable to bromine, chlorine or iodine and / or decomposing water to form a biologically active O ₂ or O ₃ oxidant.

US 5 424 032 discloses a method of treating water with harmless chemicals for the treatment of wet organisms or using • 0 • 000

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-2-ultraviolet light or electrolysis to destroy microorganisms.

The term "disinfection," as used herein, means the destruction of various strains of microorganisms to an extent that prevents the formation of biological deposits, and the disinfection of drinking water or washing water.

Because scaling and scaling are related processes, each of the terms "scaling and scaling" means both scaling and scaling.

It is an object of the present invention to provide a method of preventing or at least inhibiting the growth of microorganisms in aqueous solutions, e.g., water, and lime scale precipitation, which does not require the addition of chemicals to said solutions, and thus constitutes an environmentally harmless method. The invention solves numerous serious problems of the prior art methods. For example, there are cooling systems in which water is treated by the addition of chemicals. The discharged stream from such cooling systems cannot be used in many applications for the presence of the chemicals, and in many cases the discharged stream is discarded or requires expensive cleaning to remove the chemicals before it can be released into the environment.

Another object of the present invention is to provide a method of disinfecting aqueous liquids and scaling that allows operation at a pH of greater than 7 and even greater than 8.5.

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It has now been found, as a further object of the invention, that in a system where a DC current treatment having a combined effect of in situ biocidal production and scaling was applied to an aqueous fluid such as pure water without additives, a percentage of limescale than in the prior art, in order to achieve substantially the same disinfection and descaling results as achieved for the softened water described in the prior art.

SUMMARY OF THE INVENTION

The present invention provides a method of treating aqueous media, comprising exposing said aqueous medium in an electrolytic cell to an electrical direct current of such magnitude and at such fluid flow through said electrolytic cell to achieve a combined scale removal and disinfection effect.

The present invention further provides an aqueous fluid treatment apparatus for descaling and disinfection, comprising an electrolytic cell powered by a direct current device, said electrolytic cell being configured to allow circulation of the aqueous medium.

The amount of direct current applied to said aqueous fluid varies according to the type of aqueous medium. For example, in the case of cooling water treatment, the amount of direct current applied is about 1A / 5m ³ / h.

Aqueous media that can be treated include potable water, tap water, agricultural water, industrial water

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But not limited to water, seawater and sewage. An advantage of the present invention is that the pH at which it is possible to work is not limited so that it can be operated at a pH much higher than that of the prior art. As one skilled in the art will appreciate, at pH around 8-9, no corrosion inhibitors are required due to the nature of the water, which is another essential advantage of the invention.

The device of the present invention can be used in any irrigation system, cooling system, heating system, water supply system, and sprayer. Said irrigation systems may include, but are not limited to, sprinklers, sprinklers, and sprayers. Cooling systems include, for example, cooling towers. Heating systems include, for example, boilers, digesters, washing machines, dishwashers, rapid heaters, evaporators, radiators, steam generators, steam cleaners, modular water heaters, thermal convectors, greenhouse heating and central heating systems. Heating systems may further include, for example, showers, sinks, bidets, baths, hot tubs, such as Jakuzzi hot tubs, whirlpools, spas and pools.

steam irons, auxiliary heating,

Optionally, the aqueous medium may be further filtered, and the apparatus of the invention optionally further comprises, in the case of a liquid outlet, a filter connected to said outlet through which electrically treated aqueous fluid is driven.

BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1 schematically illustrates a water treatment device according to a preferred embodiment of the invention.

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DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process for treating aqueous solutions which achieves a combined scaling and disinfecting effect. This meets the need for numerous systems where both effects are required, such as agricultural systems, where water is distributed through the narrow nozzles of sprinklers, sprinklers and sprayers, and where even a small amount of scale and / or biological coating may cause the nozzles to block.

The treatment according to the present invention may be carried out, for example, by a unit comprising a liquid reservoir having at least one liquid inlet and one liquid outlet, e.g. a tube, further comprising at least one cathode and one anode disposed within said liquid reservoir, the anode is electrically connected to the (-) resp. (+) pole of direct current source. Said liquid inlet is connected to a water source, and said liquid outlet is connected to a target system, eg a sprinkler, sprinkler or sprayer, for which a desinfected scale-free water is required.

Furthermore, as mentioned above, the present invention is suitable for the disinfection of liquids and for descaling in systems where maintaining a pH of 7 to 10 is desired. In the method of the invention, the pH changes only locally, near the electrodes, while in other systems, where chemicals are added, the pH changes homogeneously, and can cause serious operational problems, such as corrosion.

As will be discussed below, when the invention is applied to cooling water treatment, chemicals and drains are not added

-6 This is the current that can be used in a variety of applications, such as crop irrigation. Further, as further illustrated in the following examples, the invention allows the use of water having a conductivity of 3000 με or higher, up to about 6000 gS, without causing a significant increase in corrosion. A typical pH for operation under these conditions is approximately pH 9. In this text, "gS means gSiemens unit (equal to μΩ ^-1" ). This result is unexpected and remarkable, especially since the current standard, in cooling towers using chemicals, is not more than 3000 gS, often only 2000 gS. The admission of high conductivities, while avoiding the formation of biological deposits and scale, practically means that less drainage and hence less feed water is required during operation of the cooling tower. In operation according to the invention, a saving of about 30% feed water can be achieved, and a reduction of draining by up to about 60%, resulting in substantial savings in water consumption and waste disposal.

The present invention may be practiced using any electrolytic cell. An example of such an article is described, for example, in Whitten et al. : “General Chemistry with Qualitative Analysis, Saunders College Publishing, 4th edition, p. 1213.

Obviously, two simultaneous processes (the biocidal effect and the prevention or descaling) require any other, sometimes anti-acting, conditions. Thus, to obtain a biocidal effect, it is desired to work with high currents (the rate of formation of biocidal species in water is a function of the stream) and with high flow rates. On the other hand, small flow rates are necessary to achieve a substantial anti-limescale effect, while the magnitude of the current has no effect. Furthermore, it should be noted that the pH and precipitation conditions of fe fe

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Accordingly, preferred, but not limiting, operating conditions are as follows:

The current required to obtain a substantial biocidal effect depends on the type of water to be treated and its need for oxidant. It can be estimated as follows:

A = 1 gr O _x / h where 0 _x is gr ( _eq > of the monoelecton oxidant such as Cl *, OH *, 1/20 * or Br *).

In order to obtain a substantial biocidal effect in typical water, a detectable residual amount, e.g. 0.05 ppm equivalent of active chlorine, is required. The active chlorine equivalent present in the water can be determined using conventional methods, e.g., using the Chlor-test kit from Merck KgaA, Germany, or the Lovibond kit from The Tintometer Ltd., UK, or other suitable methods.

In order to obtain a substantial anti-scale effect, the linear flow rate of the water in the electrolytic cell (calculated as the flow divided by the cell cross-section) should not exceed 500 m / h, preferably 100 m / h or less.

According to a particular embodiment, the invention is used in a Jakuzzi hot tub or spa. In such environments, another important parameter is the turbidity of the water. Normal turbidity of clean water should not exceed 0.8 NTU (normal turbidity unit). According to * 00

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In a preferred embodiment of the invention, the whirlpool bath should operate at a current density of at least 1 A / m ³ to achieve normal turbidity while avoiding scale effects and biological deposits.

The water treatment apparatus of the present invention may be formed in the form shown in Fig. 1, wherein the reference numeral 1 denotes a tube, 2 is a rectangular anode, and A is a rectangular cathode (cathode plate). The anode 2 is disposed along the longitudinal axis of the tube 2. The cathode plates 2 and 4 are disposed along the longitudinal axis of the tube 2, one on each side of the anode plate 2, and both cathodes face the anode 2- According to an alternative embodiment of the invention (not shown) instead of cathodes 2 and 4, or in addition, a tube 2 made of a metallic material has the function of cathode.

In the following examples, the apparatus substantially shown in Figure 1 was used having the following dimensions: tube 2 was a plastic tube 60 inches long and had a diameter of 10 inches, the anode was a rectangular plate made of steel. All three electrodes were each 50 inches long and 5 inches wide. The distance between each cathode and anode was inches. Of course, the above dimensions are different in various configurations and shapes of the device, and are provided by way of example only, and are not intended to limit the scope of the invention in any way.

Example 1 (comparative)

A stream of untreated water was used in a mist generator in a greenhouse in which tomatoes were grown to cool and maintain the temperature at a constant level of 25-30 ° C. As a result of scaling and the growth of microorganisms and algae around the nozzle, the nozzles are blocked and the nozzle becomes * φφφφ φ φ * φφφ

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J · · Φ • · Φ Φ • · Φ Φ • Φ Φ had to be replaced. The average nozzle life in this system was 3 to 4 days.

Example 2 (comparative).

The reverse osmosis water stream was used in the same system as in Example 1. The average nozzle life in this case was 1 to 2 months.

Example 3

The DC stream treated with the DC stream of the present invention was used in the same system as Example 1. After three months, none of the approximately 1000 nozzles were blocked, and maintenance of these nozzles was saved. Through the use of the DC treatment device of the invention, the water was disinfected and scale was removed to the extent necessary to solve the blocking problem for all practical purposes. Furthermore, the water was free of chemical additives and was suitable for a wide range of uses. Tomatoes that were irrigated with treated water showed no deterioration in growth. These results represent a significant improvement over the systems of Examples 1 and 2.

Example - ^ _ (comparative)

A stream of untreated water was used in a cooling tower operating at a flow rate of 500 m ³ / h, with a power supply of 30 m ³ / h and a drain of 10 m ³ / h. The conductivity of tap water was about 1000 μδ, and the discharge current (and hence also the recirculating water) was 3000 μβ. After two weeks, a distinct biological coating and scale was observed on the tower walls. The water in the tower was cloudy.

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Example 5 (comparative)

In the cooling tower of Example 4, a stream of water treated with polyphosphonates, sulfuric acid, and corrosion inhibitors with a pH of less than 8 was used. The result was an unstable pH value and scale and biological coating on the tower walls that were removed every three months to allow the tower to function smoothly . The metal elements showed corrosion. The water in the tower was cloudy and unsuitable for irrigation.

Example. 6

In the system of Example 4, a 50 m ³ / h recycle water stream treated with the DC current of the present invention was used at a time when the biological coating layer and scale was already present. The conductivity of the discharge current was 5000 pS. The feed was 20 m ³ / h and the discharge was 4 m ³ / h. After two weeks the layer disappeared and the water in the tower was clear. No corrosion was observed. The discharge stream was suitable for irrigation. By using the DC treatment device according to the invention, the water was disinfected to such an extent that not only an additional biological coating appeared on the tower walls, but the existing biological coating disappeared. Pure water, scaling and biological deposits, and the green use of the discharge stream of this example represents a significant improvement in the results of Examples 4 and 5.

Example.7

A Jacuzzi hot tub of 2 m ³ was used for this example. The water turbidity was 0.5 NTU. The hot tub was operated for 4 consecutive hours with 4 persons, each for 1 »00 • · 0 • 0 0 • 0 0

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000 hours, without adding chemicals. Turbidity at the end of this four-hour period was 3 NTU. Thereafter, the whirlpool was operated empty, with a water treatment cell with a maximum recycling rate of 6 / h (volumes recirculated per hour) at 10 A for 2 hours, and at the end of this period the turbidity was 0.1 NTU. The redox potential was 60 mV. The water was supplied to the bathtub as required by the level indicator regulating the water level in the bathtub.

The experiment was repeated daily for two weeks without water change, and the turbidity always decreased to the same value of 0.1 NTU.

In addition, the redox potential of water was measured about 3 hours after bathing, and consistent values were found in the range of 500-700 mV, with detectable amounts of oxidants. In addition, 150 g of scale containing mainly CaCO ₃ and Mg (OH) ₂ was removed from 2 m ^{3 of} water during this experiment.

A comparative test was also performed with currents below 2 A, and it was found that below this value no greater redox potential than 500 mV could be achieved. However, the water turbidity remained at a suitable level (0.1 NTU).

As will be appreciated by those skilled in the art, the above results are very advantageous for use in bath systems such as whirlpools. Furthermore, it should be noted that turbidity control is very important as it is undesirable to replace the water in the whirlpool as fresh water brings with it additional amounts of carbonates which cause fouling.

The foregoing description and examples are provided for illustrative purposes only and are not intended to limit the scope of the invention in any way.

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It will be apparent to those skilled in the art of modification or leakage that numerous variations and modifications can be made without departing from the spirit and scope of the invention.

Claims (19)

A method of treating aqueous media, comprising exposing said aqueous medium in an electrolytic cell to an electrical direct current of such magnitude and at such fluid flow through said electrolytic cell to achieve a combined scale removal and disinfectant effect. The method of claim 1, wherein the stream is sufficient to produce a detectable residual amount of active chlorine equivalent. The method of claim 2, wherein the residual amount of active chlorine equivalent in water is 0.05 ppm or more. Method according to one of claims 1 to 3, characterized in that the linear flow rate of the aqueous medium through the electrolytic cell is 500 m / h or less, preferably 100 m / h or less. 5. Method according to any of claims 1 to 4, characterized that aqueous medium is water of whirlpool and current density is at least 1A / m ³ . 6. Method according to any of claims 1 to 4, characterized that aqueous medium is water from cooling and the conductivity of the recirculated water is 3000 to 6000 μΞ. Method according to one of claims 1 to 4, characterized in that the aqueous medium is selected from the group consisting of tap water, agricultural water, industrial water, sea water and sewage water. Process according to any one of claims 1 to 7, characterized in that the pH of the water is maintained at a value higher than 7 The method of claim 8, wherein the pH of the water is maintained in the range of 8 to 9. An aqueous fluid treatment device for descaling and disinfection, comprising an electrolytic cell powered by a direct current device, said electrolytic cell being configured to allow the aqueous medium to circulate through the electrolytic cell. The aqueous fluid treatment device of claim 8, for use in agricultural irrigation systems. The apparatus of claim 11, wherein the irrigation systems are selected from the group consisting of sprinklers, sprayers, and sprayers. The apparatus of claim 10, for use in refrigeration systems. 14. The apparatus of claim 13, wherein the cooling system is a cooling tower. The apparatus of claim 10, for use in heating systems. -15 ** in »·· 16. The apparatus of claim 15, wherein the heating system is selected from the group consisting of boilers, digesters, washing machines, dishwashers, rapid heaters, vaporizers, radiators, steam generators, steam irons, steam cleaners, modular water heaters, auxiliary heaters, heat convectors, greenhouse heating and central heating systems. The apparatus of claim 10, for use in a water supply system. Apparatus according to claim 15, characterized in that the heating system is selected from the group comprising showers, sinks, bidets, baths, hot tubs, in particular Jakuzzi hot tubs, whirlpools, baths and pools The apparatus of claim 10, for use in a nebulizer. A cooling tower system comprising a cooling tower and a device according to claim 10, wherein the cooling tower is adapted to drain water and supply water, the conductivity of this water being 3000 to 6000 pS. 21. The method of claim 1 wherein the treatment is turbidity removal or control.