WO2018194514A1

WO2018194514A1 - Water disinfection system and method

Info

Publication number: WO2018194514A1
Application number: PCT/SG2017/050651
Authority: WO
Inventors: Tiong Soon KOH
Original assignee: Lovearth Ecolife Pte. Ltd.
Priority date: 2017-04-17
Filing date: 2017-12-27
Publication date: 2018-10-25

Abstract

The present invention relates to a safe and effective water disinfection system and method without the use of chemicals for disinfection. The water disinfection system generates electrons/charge carriers/radicals and comprises a plurality of electrodes arranged in a loop such that the polarity of the electrodes is constantly switched between the positive charge and the negative charge, generating a cyclonic flow or swirling of fluid such as water and create a vortex. This enables a constant pool of electrons/charge carriers/radicals to be present and an efficient mixing of the water to be treated and/or purified with the same, which increases the reactivity and maximises the contact time between these electrons/charge carriers/radicals and the water to be treated and/or purified and increases the reactivity, hence improving disinfection efficiency and thereby eliminating the need or use of additional chemicals for disinfection.

Description

WATER DISINFECTION SYSTEM AND METHOD

FIELD OF INVENTION

The present invention relates to cleaning and/or disinfection systems, and in particular but not exclusively, to a water disinfection system and method thereof.

BACKGROUND TO THE INVENTION

The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.

Conventional electrolytic treatment of water in electrolytic cells is used to treat water by generating disinfecting species such as chlorine, hypochlorous acid and/or oxygen- species from the water itself. In current hatchery aquaculture systems, an electrolyzer is typically used for disinfection of seawater by dissociating sodium chloride in seawater to form hypochlorite ions, inactivating bacterial populations present to undetectable levels. Disadvantages of this current method of disinfection include electrochemical reaction and degradation of the electrodes. Besides, the oxidation potential of hypochlorite ions (1.49V) is significantly lower than other species used in disinfection system such as hydroxyl radicals (2.80V), thus reducing disinfection efficiency.

In current water purification methods, boron-doped diamond conductive electrodes which have high efficiency in oxidation process and are stable from corrosion are utilised. Production of oxidants such as halides at the electrode surface oxidize organic materials that are present in the water that is to be treated into carbon dioxide and/or converts toxic compounds into biocompatible substances. In addition, the disinfectants are involved in the inactivation of microorganisms, preventing waterborne diseases. However, the cost of such water purification methods is very high due to the high cost of the electrodes and maintenance fees. Apart from water treatment and/or purification methods that utilise electrolysis for disinfection as described above, advanced oxidation processes (AOPs) are also used in water and wastewater treatment by oxidation through reactions, producing highly reactive hydroxyl radicals in the presence of ozone, hydrogen peroxide and/or ultraviolet light. To obtain potable water which is fit for consumption, water has to be properly disinfected to remove harmful substances such as biologically toxic and/or non- degradable materials. A constant pool of hydroxyl radicals is required to ensure proper disinfection of water. As such, chemicals such as hydrogen peroxide are typically added on top of ozone and ultraviolet light even in systems for treating water to obtain potable water to increase rate of hydroxyl radical generation, which is not desirable.

Therefore, there is an urgent need for a safe and effective water disinfection system and method without the use of chemicals for disinfection and that is cost effective to address the aforementioned disadvantages. The present invention seeks to provide a water disinfection system and method to overcome at least in part some of the aforementioned disadvantages.

SUMMARY OF THE INVENTION

Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of, and the like, are to be construed as non-exhaustive, or in other words, as meaning "including, but not limited to". The invention provides a safe and effective water disinfection system and method without the use of chemicals for disinfection and that is cost effective.

The water disinfection system of the present invention is driven by electrons tunnelling into the water through a thin film and involving positively and negatively charged electrodes. The electrons react with water and generate hydroxyl radicals, which are powerful disinfection agents that are involved in the removal of organic substances and inactivation of microorganisms. The electrostatic attraction of the electrons and charge carriers generated towards the oppositely charged electrodes results in cyclonic flow of water.

The water disinfection system involves positively and negatively charged electrodes coated with thin film which may be of single or multiple atomic layers of dielectric, semiconductor and piezoelectric material, advantageously preventing occurrence of electrochemical reaction on the electrodes

Electrons tunnel across the thin film and react with water via electrolysis to form hydroxyl radicals which are disinfection agents with strong oxidizing potential. In the process, there are also other positively and negatively charge carriers generated.

In a specially configured multiple electrodes system, there is one positively charged electrode and the remaining three are negatively charged. The polarity of electrodes is constantly switched such that the positively charged electrode is rotated in one direction. This results in the bias attraction of the electrons and charge carriers to the nearest oppositely charged electrode. It may create a spiral flow of electrons and charged carriers, enhancing mixing. By optimizing the interaction of electrons and water, it maximises the contact time and improves the reactivity and disinfection efficiency.

In accordance with a first aspect of the present invention, there is provided a water disinfection system for treating water, comprising: At least two electrodes immersible in a body of contaminated water to be treated;

A power source connected to the electrodes, wherein the power source is operable to charge the electrodes such that the electrodes bear either a positive charge or a negative charge,

Wherein the electrodes are configurable such that reactive species are generated, said reactive species move to an adjacent electrode in one predetermined direction, thereby resulting in bias attraction of the reactive species to the nearest oppositely charged electrode and allowing mixing of the reactive species and the contaminated water for treatment thereof.

Preferably, the water disinfection system further comprises: At least two electrodes connected and immersible in a body of contaminated water to be treated;

A power source connected to the electrodes, wherein the power source is operable to alternate polarities of the electrodes such that the polarities of each electrode switch between a positive charge and a negative charge; Wherein when in operation the electrodes are configurable such that the polarities of the electrodes are constantly alternating, allowing one charged electrode in the system such that remaining electrodes in the system are oppositely charged,

Wherein the electrodes are configurable such that the electrodes are charged in succession in one predetermined direction, thereby resulting in bias attraction of the reactive species to the nearest oppositely charged electrode and allowing mixing of the reactive species and the contaminated water for treatment thereof.

Preferably, the water disinfection system further comprises:

At least two electrodes immersible in a body of contaminated water to be treated, wherein one electrode is positioned atop of another; and

A power source connected to the electrodes, wherein the power source is operable to charge the electrodes such that a charged electrode is positioned adjacent to an oppositely charged electrode.

Preferably, the reactive species for use with the system can comprise hydroxyl radicals, hydroxyl ions, hydrogen ions and electrons for treating the contaminants in the body of water.

Preferably, the predetermined direction of the movement of the charged electrode in the system can be any one of clockwise, anti-clockwise or any direction that enables mixing of the contaminated water and the reactive species. Preferably, the electrodes can comprise a thin insulating layer to prevent electrochemical corrosion of the electrodes.

Preferably, the polarities of the electrodes can be configured such that there is one electrode bearing a positive charge and the remaining electrodes bearing negative charges. Preferably, the polarities of the electrodes can be configured such that there is one electrode bearing a negative charge and the remaining electrodes bearing positive charges. Preferably, the charged electrode for use with the disinfection system can bear a positive charge or a negative charge and positioned such that adjacent electrodes are oppositely charged.

In accordance with a second aspect of the present invention, there is provided a method for disinfecting water, comprising:

Installing a water disinfection system of the present invention;

Connecting at least two electrodes to a power source and immersing the electrodes in a body of contaminated water;

Charging the electrodes by applying power such that the electrodes bear either a positive charge or a negative charge;

Preferably, the reactive species for use with the disinfection method can comprise hydroxyl radicals, hydroxyl ions, hydrogen ions and electrons for treating the contaminants in the body of water.

Preferably, the predetermined direction for movement of the charged electrode can be any one of clockwise, anti-clockwise or any direction that enables mixing of the contaminated water and the reactive species.

The electrodes for use with the disinfection method can comprise a thin insulating layer to prevent electrochemical corrosion of the electrodes.

Preferably, the charged electrode for use with the disinfection method can bear a positive charge or a negative charge and positioned such that adjacent electrodes are oppositely charged.

In accordance with a third aspect of the present invention, the use of a water disinfection system for cleaning a contaminated receptacle, comprising: Installing a water disinfection system of the present invention;

Providing water in the contaminated receptacle and immersing electrodes therein;

Wherein the electrodes are configurable such that reactive species are generated, said reactive species move to an adjacent electrode in one predetermined direction, thereby resulting in bias attraction of the reactive species to the nearest oppositely charged electrode and allowing mixing of the reactive species and the contaminated water for cleaning thereof.

The present invention has at least the following advantages:

1. The water disinfection system of the present invention uses hydroxyl radicals, which are powerful disinfection agents, and eliminates the use of chemicals for disinfection, hence preventing side reactions from occurring such as bromination. The unique configuration of the system comprises a plurality of electrodes arranged in a loop such that the polarity of the electrodes is constantly switched between the positive charge and the negative charge based on the following: (i) At any one point, there is only one positively charged electrode while the remaining electrodes are negatively charged; and (ii) the positive charge is being rotated among the electrodes in one direction around the loop, thereby generating a cyclonic flow or swirling of fluid such as water, creating a vortex. This enables a constant pool of hydroxyl radicals to be present and an efficient mixing of the water to be treated and/or purified with such radicals, which increases the reactivity and maximises the contact time between these radicals and the water to be treated and/or purified and increases the reactivity, hence improving disinfection efficiency and thereby eliminating the need or use of additional chemicals for disinfection.

2. The present invention provides self-cleaning capabilities due to the specially configured system which enables the swirling of water to be achieved. Currently, cleaning of tanks and pipes is manual and labour intensive. Therefore, with the present water disinfection system, the receptacle or conduit that is used to hold the water for treatment and/or purification can also be cleaned and/or disinfected either simultaneously during the water treatment and/or purification process, or separately on another occasion as desired. As such, it saves time and hassle for cleaning and also minimizes the use of water and pressure. Other aspects and advantages of the invention will become apparent to those skilled in the art from a review of the ensuing description, which proceeds with reference to the following illustrative drawings of various embodiments of the invention.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will now be described, by way of illustrative example only, with reference to the accompanying drawings, of which:

FIG. 1 is a cross sectional view of a water disinfection system in accordance with an embodiment of the present invention;

FIG. 2 is a cross sectional view of the water disinfection system of FIG. 1 applied in a pipe with a single pair of electrodes; FIG. 3 is a cross sectional view of the water disinfection system of FIG. 2 with multiple pairs of electrodes;

FIG. 4 is a cross sectional view of the water disinfection system of FIG. 3 to create a cyclonic effect; (A) shows a first electrode being positively charged whilst each of a second, a third and a fourth electrode being negatively charged; and (B) shows the second electrode being positively charged whilst each of the first, third and fourth electrode being negatively charged;

FIG. 5 is an illustration of the water disinfection system of FIG. 4 with multiple pairs of electrons and connected to a power supply and electrical interconnect;

FIG. 6 is an illustration of the water disinfection system of FIG. 5 with red indicator dye in the plate colors the colonies of Aerobic Count (AC) and Coliform Count (CC) using 3M Petrifilm E. co/zVColiform Count Plates; and

FIG. 7 shows a phase shifting occurrence in the multiple pairs of electrodes of the water disinfection system of FIG. 3; (A) shows a single waveform based on voltage (V) plotted against 0=cot; (B) shows a phase transformation with multiple waveforms based on voltage (V) plotted against 0=cot; (C) shows a cross sectional view of the multiple pairs of electrodes of the water disinfection system; and (D) shows the phase shifting occurrence of the multiple pairs of electrodes of the water disinfection system based on voltage (V) plotted against 0=cot.

DETAILED DESCRIPTION

Particular embodiments of the present invention will now be described with reference to the accompanying drawings. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. Additionally, unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs.

The use of the singular forms "a", an", and "the" include both singular and plural referents unless the context clearly indicates otherwise. The use of "or", "/" means "and/or" unless stated otherwise. Furthermore, the use of the terms "including" and "having" as well as other forms of those terms, such as "includes", "included", "has", and "have" are not limiting.

The use of "reactive species" as used herein refers to radicals, electrons and charged carriers such as hydroxyl radicals, hydroxyl ions, hydrogen ions and the like or any occurring species during electrolysis reaction.

With reference to Figures 1 to 5, there is described a safe and effective water disinfection system and method for treating and/or purifying fluids such as water without the use of chemicals for disinfection in accordance with embodiments of the present invention. The disinfection system and method can also be used to clean and/or disinfect any receptacles or conduits such as pipes, tanks, containers, that are of any shape and size.

The water disinfection system 10 of the present invention is driven by electrons tunnelling into the water through a thin film 11. The electrons react with water and generate hydroxyl radicals, which are powerful disinfection agents. The electrostatic attraction of the electrons and charge carriers generated towards the oppositely charged electrodes results in cyclonic flow of water.

The water disinfection system involves positively 12 and negatively 13 charged electrodes coated with a thin film 11 which may be of single or multiple atomic layers of dielectric, semiconductor and piezoelectric material, advantageously preventing occurrence of electrochemical reaction on the electrodes.

Electrons tunnel across the thin film 11 and react with water via electrolysis to form hydroxyl radicals which are disinfection agents with strong oxidizing potential. In the process, there are also other positively and negatively charge carriers generated. In a specially configured multiple electrodes disinfection system 20, there is one positively charged electrode 22 and the remaining three are negatively charged 23. The polarity of electrodes is constantly switched such that the positively charged electrode 22 is rotated in one direction. This results in the bias attraction of the electrons and charge carriers to the nearest oppositely charged electrode. It may create a spiral flow of electrons and charged carriers. By optimizing the interaction of electrons and water, it maximises the contact time and improves the disinfection efficiency.

Referring to Figures 1 and 2, there is described a water disinfection system 10 that comprises a single pair of electrodes, i.e., two electrodes, arranged in a pipe 14. One of the electrodes is positively charged 12 while the other electrode is negatively charged 13. Each of the electrodes is coated with a thin film 11 which may be of single or multiple atomic layers of dielectric, semiconductor and piezoelectric material. Advantageously, the dielectric property of the film prevents electrochemical reaction of the electrodes which maximises the life span of the electrodes.

When the system is in use, the polarity of the two electrodes is configured to constantly switch between positive and negative, resulting in the bias attraction of the electrons/charge carriers/radicals generated to the oppositely charged electrode. This creates cyclonic movement in the water to be treated and/or purified that is present in the pipe which maximising the contact time between the electrons/charge carriers/radicals and the water to be treated and/or purified and increases the reactivity. With reference to Figures 3 to 5, there is described a water disinfection system in accordance with another embodiment of the present invention. The disinfection system 20 comprises multiple pairs of electrodes, in particular two pairs of electrodes or four electrodes, arranged in a loop in a receptacle or conduit 24, which is in the form of a pipe 24 in this particular embodiment. Each of the electrodes is coated with a thin film 21 which may be of single or multiple atomic layers of dielectric, semiconductor and piezoelectric material. Advantageously, the dielectric property of the film prevents electrochemical reaction of the electrodes which increases the life span of the electrodes.

The water disinfection system generates electrons/charge carriers/radicals such as hydroxyl radicals, which are powerful disinfection agents. The unique configuration of the system comprises four electrodes arranged in a loop such that the polarity of the electrodes is constantly switched between the positive charge and the negative charge based on the following: (i) At any one point, there is only one positively charged electrode 22 while the remaining electrodes are negatively charged 23; and (ii) the positive charge is being rotated among the electrodes in one direction around the loop, thereby generating a cyclonic flow of fluid such as water or swirling of water creating a vortex (see Figure 4). This enables a constant pool of hydroxyl radicals to be present and an efficient mixing of the water to be treated and/or purified with such radicals, which increases the reactivity and maximising the contact time between these radicals and the water to be treated and/or purified, hence improving disinfection efficiency and thereby eliminating the need or use of additional chemicals for disinfection. Hence, the cost is also reduced as no additional chemicals are required to be added for disinfection.

It would be appreciated that the mixing flow can be in any direction, insofar as the system promotes mixing of the water and the reactive species, such as electrons and the radicals. The mixing flow is not necessary limited to spiral/cyclonic flow.

It would be appreciated that the configuration of the electrodes can vary and render the swirling of the water for mixing of the water and the reactive species for treatment thereof. In another embodiment of the present invention, there is described a disinfection system comprising multiple electrodes in a stacked loop, forming a spiral pattern. Each electrode is elevated diagonally atop adjacent electrodes, wherein the adjacent electrodes bear opposite charges from their immediate neighbouring electrodes. All electrodes are held in their respective charges. This enables the creation of diagonal flow pattern of the water to be treated with the radicals or reactive species, thereby increasing the reactivity and maximising the contact time between the reactive species and the water.

Referring to Figure 5, a contaminated liquid comprising microorganisms was treated using the water disinfection system as described in Figure 1 to 4. In another embodiment, electrodes without the thin film coating can be used in the water disinfection system of the present invention. The disinfection system 20 comprises multiple pairs of electrodes of metal, in this case 8 stainless steel electrodes are arranged in a loop and connected to a microcomputer 25 via a relay module 26, which acts as a switch for controlling the flow of current. The electrodes perform the function of donating metal ions to the water, donating or accepting electrons from molecules in the water and facilitate the oxidation and reduction reactions in the system.

A contaminated liquid comprising microorganism was added to a beaker and the electrodes are immersed in the liquid. During operation of the present invention, a power supply 27 may function as constant current source for the electrodes. Variable switching of the polarity of the electrodes is provided by the relay module 26, such that there is only one positively-charged electrode in the system, while the remaining electrodes are negatively charged.

The pre-treatment and post- treatment colony counts of Aerobic Count (AC) and Coliform Count (CC) were carried out using 3M Petrifilm E. co/zVColiform Count Plates for the enumeration of aerobic bacteria.

It would be appreciated that the AC is an indicator of microorganism populations in a sample and can be used to indicate the quality and spoilage level of the sample, whereas the CC is a test of water contamination in which the number of colonies of coliform- bacteria Escherichia coli (E. coli) and provides an indication of the sanitary condition of a water supply.

The colony counts of Aerobic Count (AC) and Coliform Count (CC) using 3M Petrifilm E. co/z^'/Coliform Count Plates are illustrated in Figure 6, in which a red indicator dye in the plate colors the colonies. In accordance with the Interpretation Guide for the use of the Petrifilm, there is a high concentration of pre-treatment colonies and should be recorded as "TNTC (Too Numerous to Count)". For ease of comparison, the pre- treatment colony count (estimated) is indicated as >100. The colony counts of AC and CC are significantly reduced after treatment of the contaminated water.

Referring to Figure 7, phase shifting occurs due to the switching of polarities of the electrodes which is denoted by stages A to D (see Figure 7D).

• Phase transformation involves the combination of multiple single waveforms (see Figures 7A and 7B). It can be in-phase or out-of-phase.

• Phase shifting occurs due to the switching of polarities of the electrodes (see Figures 7C and 7D).

• With reference to Figure 7D, in stage A, the voltage of the positively charge electrode (1) is in the positive phase. Electrodes (2), (3) and (4) which are negatively charge remain in the negative phase.

• Upon switching of polarity in stage B, there is a change of phase. The voltage of electrode (2) now become in the positive phase. The negatively charge electrodes (1), (3) and (4) are in the negative phase.

• Stages C and D demonstrate the polarity switch of the positive charge to electrodes (3) and (4) respectively.

It would be appreciated that in other embodiments of the present invention, other numbers of electrodes can also be used in the disinfection system, such as three electrodes, five electrodes, six electrodes, and so on.

Advantageously, the water disinfection system and method can be used in various applications, in particular but not limited to:

Water disinfection system The system generates electrons/charge carriers/radicals such as hydroxyl radicals which have disinfection capability by removing the organic substances and deactivation of microorganisms in the water.

2) Self-cleaning capability tanks/pipes Hydroxyl radicals, generated from the tunnelling of electrons into the water, possess disinfection capability. Besides, the swirling of water due to the specially configured multiple electrodes system creates a vortex, simultaneously cleaning the tanks/pipes during the disinfection process. It advantageously helps to enhance the mixing and optimize the disinfection efficiency. 3) Measuring instrument

Flow of water will interfere with the electron tunnelling. The presence of the flow of water can be determined from the change in the electrical current. Alternatively, the flow rate of water could be detected from the increase or decrease in the electrical current which is proportional to the water flow rate. It would be appreciated that in other embodiments of the present invention, the water disinfection system can be installed into existing receptacles or containers holding a body of water to be treated.

It is to be understood that the above embodiments have been provided only by way of exemplification of this invention, and that further modifications and improvements thereto, as would be apparent to persons skilled in the relevant art, are deemed to fall within the broad scope and ambit of the present invention described herein. It is further to be understood that features from one or more of the described embodiments may be combined to form further embodiments.

Claims

1. A water disinfection system for treating water, comprising:

At least two electrodes immersible in a body of contaminated water to be treated;

2. The water disinfection system according to claim 1, further comprising:

At least two electrodes connected and immersible in a body of contaminated water to be treated; A power source connected to the electrodes, wherein the power source is operable to alternate polarities of the electrodes such that the polarities of each electrode switch between a positive charge and a negative charge;

Wherein when in operation the electrodes are configurable such that the polarities of the electrodes are constantly alternating, allowing one charged electrode in the system such that remaining electrodes in the system are oppositely charged,

3. The water disinfection system according to claim 1, further comprising:

At least two electrodes immersible in a body of contaminated water to be treated, wherein one electrode is positioned atop of another; and A power source connected to the electrodes, wherein the power source is operable to charge the electrodes such that a charged electrode is positioned adjacent to an oppositely charged electrode.

4. The water disinfection system according to any of the preceding claims, wherein the reactive species comprise hydroxyl radicals, hydroxyl ions, hydrogen ions and electrons for treating the contaminants in the body of water.

5. The water disinfection system according to any of the preceding claims, wherein the predetermined direction for movement of the charged electrode in the system can be any one of clockwise, anti-clockwise or any direction that enables mixing of the contaminated water and the reactive species.

6. The water disinfection system according to any of the preceding claims, wherein the electrodes comprise a thin insulating layer to prevent electrochemical corrosion of the electrodes.

7. The water disinfection system according to claim 2, wherein the polarities of the electrodes can be configured such that there is one electrode bearing a negative charge and the remaining electrodes bearing positive charges.

8. The water disinfection system according to claim 2, wherein the polarities of the electrodes can be configured such that there is one electrode bearing a positive charge and the remaining electrodes bearing negative charges.

9. A water disinfection method for treating water, comprising:

Installing a water disinfection system according to any of claims 1 to 8;

10. The water disinfection method according to any of the preceding claims, wherein the reactive species comprise hydroxyl radicals, hydroxyl ions, hydrogen ions and electrons for treating the contaminants in the body of water.

11. The water disinfection method according to any of the preceding claims, wherein the predetermined direction for movement of the charged electrode can be any one of clockwise, anti-clockwise or any direction that enables mixing of the contaminated water and the reactive species.

12. The water disinfection method according to any of the preceding claims, wherein the electrodes comprise a thin insulating layer to prevent electrochemical corrosion of the electrodes.

13. The use of a water disinfection system for cleaning a contaminated receptacle, comprising: Installing a water disinfection system according to any of claims 1 to 8;