WO2021175795A1

WO2021175795A1 - Liquid treatment product and method with a gas-producing compound

Info

Publication number: WO2021175795A1
Application number: PCT/EP2021/055077
Authority: WO
Inventors: Nicholas John JACKSON; Paul DEN HOLLANDER
Original assignee: Aqua Bioscience Limited
Priority date: 2020-03-02
Filing date: 2021-03-01
Publication date: 2021-09-10
Also published as: GB202003005D0; GB2592761A; GB202210311D0; GB2607225A; GB202102881D0

Abstract

Aspects of the present invention relate to a liquid treatment product. The liquid treatment product may facilitate removal of particulates from a liquid. The liquid may be water, for example water in a swimming pool. The treatment product may include a flocculant for forming flocs of dispersed particles. The treatment product may also include a gas-producing compound for producing a gas to promote buoyancy of the flocs formed by the flocculant. Aspects of the present invention also relate to a method of treating a liquid to remove dispersed particles; and to a method of manufacturing a water treatment product.

Description

LIQUID TREATMENT PRODUCT AND METHOD WITH A GAS-PRODUCING WO 2021/175795 COMPOUND PCT/EP2021/055077

TECHNICAL FIELD

The present disclosure relates to a liquid treatment product and method. Aspects of the invention relate to a liquid treatment product for facilitating removal of particles and/or microdroplets dispersed in a liquid; and to a method of treating a liquid to remove dispersed particles and/or microdroplets. The liquid may be water, for example water in a swimming pool. Aspects of the invention also relate to a method of manufacturing a water treatment product.

BACKGROUND

It is known in water treatment systems and methods to provide flocculants and clarifiers to remove particles that are too small to be captured by filter media, such as Cryptosporidium, and to improve water clarity. The flocculant or clarifier may be used seasonally, for example in Spring or Summer, to get a pool back from going green over Winter. Alternatively, or in addition, the flocculant or clarifier may be used after an algae bloom and/or to improve filtration efficiency. Known flocculants and clarifiers usually work in one or both of the following ways:

• The particles are caused to bind together to form larger particles (known as floes or clusters of particles) which will then sink or fall to the bottom of the swimming pool for removal by vacuuming. Alternatively, the larger particles may be filtered by an existing filter and, as the filter blocks, smaller particles will be filtered.

• A gel-like layer is formed on the filter bed and, as water passes through the filter, this layer will take out smaller particles than the filter media alone.

A known flocculant is aluminum sulfate which may be either a liquid or a powder. The aluminum sulfate is spread over the surface of the pool. The pump is switched off and the system is left to allow flocculant to fall to the floor of the pool and bind the particles together to form larger particles. After a suitable time period has elapsed, typically at least twelve (12) hours, the debris on the floor of the pool will need to be vacuumed to waste, carefully, so as not to put the particles back into suspension. This product may also remove metals from the water.

A clarifier is typically a liquid which is added to the pool water with the circulation system running. The clarifier causes the particles to bind together into larger ones which will then fall to the floor or be taken out by the pool filtration system. Depending on the pool system, this can take up to three (3) to four (4) days to clear the swimming pool. As the filter will be blocking, the flow will decrease and pressure will increase so a backwash of the filter will be necessary. Another type of flocculant is a gel cube which is introduced into the pump basket or skimmer basket. The gel cube dissolves over time and forms a gel-like substance on the filter bed. This type of product can take three (3) to four (4) days to dissolve and start working. The flow and pressure may be compromised, and the filter will likely need to be backwashed. For commercially operated swimming pools, a common flocculant is polyaluminum chloride (PAC) which is constantly dosed into a filtration system upstream of a filter. The PAC causes floes to form and creates a gel like substance on the filter bed. The PAC may be introduced to capture Cryptosporidium.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a water treatment product; a method of treating water; and a method of manufacturing a water treatment product as claimed in the appended claims.

Aspects of the present invention relate to a liquid treatment product. The liquid treatment product may facilitate removal of particulates from a liquid. Alternatively, or in addition, the liquid treatment product may facilitate removal of other liquids, such as oil. The liquid may be water, for example water in a swimming pool. The treatment product may include a flocculant for floccing particles dispersed in water. The flocculant may agglomerate/aggregate the particles to form floes. The treatment product may also include a gas-producing compound for producing a gas to promote buoyancy of the floes formed by the flocculant. Aspects of the present invention also relate to a method of treating a liquid to remove dispersed particles.

According to an aspect of the present invention there is provided a water treatment product comprising: a flocculant for aggregating particles dispersed in water to form floes; and a gas-producing compound for producing a gas to promote buoyancy of the floes formed by the flocculant.

At least in certain embodiments, the water treatment product may reduce the turbidity of water. The water treatment product is suitable for treating water, for example in a swimming pool. The water treatment product is an additive that can be added to a body of water to facilitate removal of particles. The particles may be dispersed within the water, for example as a colloidal dispersion or a suspended dispersion. In swimming pools in general, clarity is extremely important. If the pool water clarity deteriorates to a level where the bottom of the pool is no longer visible, the swimming pool may be classed as unsafe and legislation may require that it is closed. The prior art techniques discussed herein may take one or more days to address this problem. At least in certain embodiments, the water treatment product described herein may operate more expediently, potentially enabling the swimming pool to be re-open after a shorter cleaning interval. In use, the flocculant in the water treatment product causes the particles dispersed throughout the water to cluster together to form floes. The gas- producing compound is typically a chemical compound which is an active ingredient in the water treatment product. In use, the gas-producing compound may react with water to produce a gas.

The flocculant (or flocculating agent) is suitable for floccing or aggregating the dispersed particles to form floes (i.e. clusters of the particles). The formation of floes facilitates removal of the particles from the water. In use, the gas-producing compound produces a gas, such as oxygen, which may increase the buoyancy (i.e. reduces the density) of the floes causing them to float or rise in the water. The gas may form bubbles which adhere to or bond to the floes. For example, different electrical charges may generate electrostatic forces which cause the bubbles to bond to the floes. The gas produced by the gas-producing compound may render the floes positively buoyant (i.e. less dense than water). In other words, the relative density of the floes (to that of water) may be less than one (1).

The water treatment product may comprise a gelling agent for forming a gel (a semi-rigid colloidal dispersion). The gelling agent may be separate from the flocculant. Alternatively, the flocculant may be suitable for forming a gel (or colloidal dispersion). For example, the flocculant may comprise or consist of polyaluminum chloride (PAC) which reacts with water to form a gel. The gel may be suitable for retaining the particles in the floes and/or for binding the floes together. The particles may adhere to or be encapsulated within the gel. The gas produced by the gas-producing compound may be introduced into the gel, for example to form bubbles within the gel. The dispersed gas in the gel may provide an additional phase within the gel. The gas produced by the gas-producing compound may render the gel positively buoyant (i.e. less dense than water). In other words, the relative density of the gel (to that of water) may be less than one (<1 ).

The gas produced by the compound is preferably non-combustible or non-toxic. The gas- producing compound may comprise or consist of an oxygen-producing compound. The gas- producing compound may react with water to generate oxygen. Advantageously, oxygen may oxidize organic material in the water, which may improve clarity. It will be understood that other gases may also be produced during the reaction. The gas-producing compound may comprise or consist of sodium percarbonate. The sodium percarbonate may have a concentration greater than or equal to 90% or 95%, for example. The sodium percarbonate may have a concentration of approximately 98.8%.

In a variant the gas-producing compound may comprise or consist of a hydrogen-producing compound. The hydrogen-producing compound may comprise or consist of a nano-galvanic aluminum-based powder. Alternatively, the hydrogen-producing compound may comprise or consist of a sodium boron compound (NaBH4).

The gas-producing compound may constitute 10% to 40% inclusive of the water treatment product by mass. The gas-producing compound may constitute 15% to 30% inclusive of the water treatment product by mass; or 20% to 25% inclusive of the water treatment product by mass.

In variants, the gas-producing compound may comprise or consist of a carbon dioxide producing compound, and/or a carbon monoxide producing compound. For example, the gas- producing compound may comprise sodium hydrogen carbonate (NaHCOs) which combines with an acid to produce carbon dioxide.

Alternatively, or in addition, the gas-producing compound may comprise an addition compound of sodium carbonate and hydrogen peroxide for generating oxygen when added to water. The addition compound may be mixed with a water-soluble solid matter of manganese dioxide or salts of metal such as iron, copper, or lead to be used as a catalyst. A water-soluble binding agent may be used to bind the manganese dioxide or salts of metal.

The water treatment product may comprise a catalyst to promote production of the gas. The catalyst may, for example, decompose hydrogen peroxide to produce a gas. The catalyst may comprise one or more of the following: potassium iodide, potassium permanganate, silver, platina, enzyme Catalase and electrolysis.

The gas-producing compound may produce one or more gases. The water treatment product may comprise more than one gas-producing compound. The water treatment product may comprise two or more gas-producing compounds. The gas-producing compounds may produce different gases, for example oxygen and carbon dioxide. The water treatment product may comprise an oxidizer. The oxidizer may be suitable for performing non-chlorine oxidation of the water. The oxidizer may be suitable for performing so-called shock oxidation of the water. The oxidizer may, for example, comprise potassium monopersulfate. The potassium monopersulfate may have a concentration greater than or equal to 90% or 95%, for example. The potassium monopersulfate may have a concentration of approximately 99%.

The oxidizer may constitute 1% to 10% inclusive of the water treatment product by mass. The oxidizer may constitute 1% to 5% inclusive of the water treatment product by mass. The oxidizer may also generate a gas which may increase buoyancy of the floes.

The flocculant may constitute 45% to 80% inclusive of the water treatment product by mass. The flocculant may constitute 50% to 75% inclusive of the water treatment product by mass. The flocculant may constitute 55% to 65% inclusive of the water treatment product by mass.

The flocculant (or coagulant) may comprise or consist of polyaluminum chloride (PAC). The polyaluminum chloride (PAC) may have a concentration in the range 10% to 50%; or 20% to 40%. The polyaluminum chloride (PAC) may have a concentration of approximately 20%, 30%, 40% or 50%. Alternatively, the flocculant may comprise or consist of ferric sulfate.

The flocculant may comprise or consist of aluminum sulfate and aluminum oxide. For example, the aluminum sulfate (CAS No. 10043-01 -3) may comprise greater than or equal to 40%, 50%, or 60% of the flocculant; and the aluminium oxide (CAS No. 1344-28-1 ) may comprise in the range 1% to 10% inclusive of the flocculant.

The flocculant may comprise or consist of aluminum chlorohydrate. For example, the aluminum chlorohydrate (CAS No. 12042-91-0) may comprise in the range 10% to 30% inclusive of the flocculant.

The flocculant may be in the form of a solid. The flocculant may be in the form of flakes, granules or powder. Alternatively, the flocculant may be in the form of a liquid.

The water treatment product may comprise a plurality of structural components which provide a base or seed for forming the floes. The structural components may be at least substantially insoluble in water. The structural components may be larger than the particles, for example to facilitate filtration or removal from the water. The particles may agglomerate or collect on the structural components to form the floes. The structural components may comprise or consist of cellulose, for example.

The water treatment product may comprise cellulose. The cellulose may have a concentration greater than or equal to 90%, 95% or 98%, for example. The cellulose is at least substantially insoluble in water. The cellulose may facilitate or promote floccing or aggregation of dispersed particles to form floes. The cellulose may constitute 5% to 25% by mass of the water treatment product.

The water treatment product may comprise ethylenediaminetetraacetic acid (EDTA). The ethylenediaminetetraacetic acid (EDTA) may have a concentration greater than or equal to 30%, 40% or 50%, for example. The EDTA may dissolve limescale. The EDTA is capable of chelating various metals. Alternatively, or in addition, the water treatment product may comprise Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) (CAS No. 67-43-6) for chelating metals.

The ratio of the flocculant to the gas-producing compound may be in the range 1 :1 to 5:1 by mass. The ratio of the flocculant to the gas-producing compound may be in the range 2:1 to 4:1 by mass. The ratio of the flocculant to the gas-producing compound in the water treatment product may be approximately 3:1 by mass.

The water treatment product may be in a liquid phase or a solid phase. The water treatment product may comprise or consist of tablets, flakes, granules or powder.

According to a further aspect of the present invention there is provided a water treatment method comprising: introducing a water treatment product into water, the water treatment product comprising a flocculant and a gas-producing compound; the flocculant aggregating particles dispersed in the water to form floes, and the gas- producing compound producing a gas which promotes buoyancy of the floes; and removing the floes formed by the flocculant at or near the surface of the water.

According to a further aspect of the present invention there is provided a water treatment method comprising: introducing a flocculant to aggregate particles dispersed in the water to form floes; introducing a gas-producing compound to produce a gas which promotes buoyancy of the floes; and removing the floes formed by the flocculant at or near the surface of the water. The flocculant and the gas-producing compound may be introduced into the water at the same time. For example, the flocculant and the gas-producing compound may be combined in a water treatment product of the type described herein.

Alternatively, the flocculant and the gas-producing compound may be introduced into the water consecutively (i.e. one after the other). The flocculant may be introduced before or after the gas-producing compound.

The flocculant causes floccing or aggregation of dispersed particles to form floes (or clusters of particles). The formation of floes facilitates removal of the particles from the water. The gas- producing compound produces a gas, such as oxygen, which may increase the buoyancy (i.e. reduce the density) of the floes causing them to float or rise in the water. The gas produced by the water treatment product may render the floes positively buoyant (i.e. less dense than water). In other words, the relative density of the floes (to that of water) is less than one (<1). The floes may sink or fall within the water when they are formed.

The floes may initially sink to the bottom of the body of water. The gas produced by the water treatment product may subsequently cause the floes to rise or float in the body of water. The production of gas may cause debris, such as small leaves, at the bottom of the body of water to rise to the surface.

The water treatment product may comprise a gelling agent for forming a gel (a semi-rigid colloidal dispersion) to retain the particles in the floes and/or to join the floes together. The gelling agent may be distinct from the flocculant. At least in certain embodiments, the flocculant may form a gel. Thus, the flocculant may function as the gelling agent. The particles may adhere to or be encapsulated within the gel. The gas produced by the gas-producing compound may be introduced into the gel. The gas may form bubbles within the gel. The dispersed gas in the gas may provide an additional phase within the gel. Alternatively, or in addition, the gas produced by the gas-producing may form bubbles which adhere to or bond to the floes.

The floes may rise or float to an upper region of the water. The method may comprise removing the floes from the upper region of the water. The floes may rise or float to, or proximal to, the surface of the water. The method may comprise removing the floes from the surface of the water. At least in certain embodiments, the removal of floes at or close to the surface of the water may be performed more readily than the removal of floes which have a neutral buoyancy (i.e. a relative density substantially equal to one (=1)) or a negative buoyancy (i.e. a relative density greater than one (>1)).

In certain embodiments, the water treatment product may form a gel. The gel may retain the particles in the floes (thereby maintaining the integrity of the floes). The gel may conjoin a plurality of the floes into larger bodies or masses. The floes may collect on the surface of the water. The gel may cause the floes to form a conjoined layer on the surface of the water. The method may comprise removing the surface layer comprising gel and floes formed by the particles. The thickness of the surface layer is dependent on the dosage of the water treatment product. In certain embodiments, the surface layer may have a thickness of 1 mm, 2mm or 3mm. A higher dosage may result in the formation of a surface layer having a thickness of up to 5mm, 10mm or 20mm. The surface layer may have a thickness greater than 2mm, 5mm or 10mm depending on the dosage.

The surface layer may be removed from the water by a skimmer apparatus. The method may comprise using a skimmer to remove the surface layer. The method may comprise configuring the skimmer to discharge the collected surface layer to waste.

The method may comprise removing the floes formed by the flocculant using an overflow system. The overflow system may be in communication with a balance tank. The floes may accumulate in the balance tank. The method may comprise removing the floes from the balance tank.

A filtration system may comprise a skimmer for removing water from the surface of the body of water. For example, a swimming pool filtration system may comprise a skimmer for removing water from the surface of the swimming pool. A skimmer is typically used to remove debris floating on the surface of the water. The water collected by the skimmer is typically pumped to a filter apparatus to remove the debris. The filtered water is then pumped back into the body of water. The process may be performed continuously with the water circulating through the filtration system. The method according to the present invention may utilise the skimmer to remove the surface layer comprising gel and floes formed by the particles. The removal of the floes from the water may comprise configuring a filtration system to discharge water from the skimmer directly to waste. Advantageously, this may avoid transferring bacteria, viruses, protozoa (such as Cryptosporidium), microorganisms, etc. from the body of water into a filter apparatus, for example into a filter bed. This may avoid or reduce contamination of the filter apparatus. The method may comprise establishing a fluid connection from the skimmer to a waste outlet to discharge the surface layer and water directly to waste. A valve, such as a multi-port valve (MPV), may be operated to connect the skimmer to the waste pipe.

The filtration system may comprise one or more pump for pumping water through a filter apparatus. The method may comprise deactivating (i.e. switching OFF) the pump prior to or concurrent with introducing the water treatment product into the water. The pump may remain deactivated (OFF) while the floes form. The method may comprise subsequently activating the pump (i.e. switching ON) to pump the water from the skimmer to waste. The pump may be activated after the floes have formed and risen to the surface of the water, for example to form a surface layer. The skimmer may remove the surface layer comprising the gel and floes. The pump may pump these directly to waste, thereby removing the particles from the water and bypassing the filter apparatus.

The water treatment product may comprise more than one gas-producing compound.

The method may be performed to treat water in a swimming pool or pond, for example. The water may, for example, be the water in a swimming pool, a bathing pool, a lido or a pond. The water treatment method may comprise treating water in a swimming pool. At least in certain embodiments, the method may facilitate removal of particles dispersed in the water. The particles may be adhered or bonded to each other.

The water treatment may be performed following an event in a swimming pool, such as a chemical imbalance or problem.

The water treatment product may comprise a solid, for example in the form of tablets, flakes, granules or powder. The water treatment product may form a gel (or a colloidal dispersion) which retains the particles in the floes. The water treatment product may be of the type described herein.

The method may comprise manually or automatically removing the floes at or near the surface of the water. The method may comprise skimming a surface of the water to remove the floes. The surface may be skimmed by a skimmer. The skimmer may, for example, form part of a filtration system.

The floes may be removed by a filtration system. The filtration system may subsequently be cleaned. For example, the method may comprise backwashing a filter apparatus to discharge the floes to waste. The gas-producing compound may produce oxygen. The oxygen may form bubbles which adhere to or are bonded to the floes of particles.

According to a further aspect of the present invention there is provided a water treatment product comprising: a flocculant for aggregating droplets and/or microdroplets of a liquid contaminant dispersed in water; and a gas-producing compound for producing a gas to promote buoyancy of the aggregated droplets and/or microdroplets. The liquid may be an oil.

According to a further aspect of the present invention there is provided a method of manufacturing a water treatment product, the method comprising mixing a flocculant and a gas-producing compound. The flocculant and gas-producing compound may be distributed throughout the resulting composition. Thus, the water treatment product may be added to water in a single dose. The relative proportion of the flocculent and the gas-producing compound are predetermined in the water treatment product, thereby ensuring that they are present in the appropriate ratio. The ratio of the flocculant to the gas-producing compound in the water treatment product may be in the range 1 :1 to 5:1 by mass. The ratio of the flocculant to the gas-producing compound in the water treatment product may be in the range 2:1 to 4:1 by mass. The ratio of the flocculant to the gas-producing compound in the water treatment product may be 3:1 by mass. The flocculant may comprise one or more of the flocculants described herein. The gas-producing compound may comprise one or more of the compounds described herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic representation of a swimming pool and filtration system;

Figure 2 shows a schematic representation of a vertical section of the water in the swimming pool shown in Figure 1 having solid particles dispersed therein;

Figure 3 shows a schematic representation of the introduction of the water treatment product to the water;

Figure 4 shows a schematic representation of the formation of floes of particles following the introduction of the water treatment product;

Figure 5 shows a schematic representation of the generation of oxygen bubbles by the water treatment product;

Figure 6 shows a schematic representation of the floes collect at the surface of the water; and

Figures 7 shows a block diagram illustrating the water treatment method according to an embodiment of the present invention.

DETAILED DESCRIPTION

A water treatment product 1 (shown schematically in Figure 3) and water treatment method in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures. As described herein, the water treatment product 1 is a composition of active ingredients, including a flocculant and a gas-producing compound. As described herein, a dose of the water treatment product 1 is introduced into a body of water to facilitate removal of particles dispersed therein. The water treatment product 1 and related method are described herein with reference to treating water in a swimming pool 2. The water treatment product 1 according to the present embodiment may be considered as a swimming pool treatment composition or additive. Nonetheless, it will be understood that the water treatment product 1 and method are not limited to this application.

The water treatment product 1 and method described herein are suitable for removing particles dispersed in water. The particles are contaminants which adversely affect the clarity of the water. The particles are insoluble (in water), thereby forming a heterogeneous mixture with the particles dispersed throughout the water. The particles and water may form a colloid, a suspension or a dispersion. The mixture may comprise particles of a range of sizes dispersed throughout the water. The water treatment is performed periodically, for example at predetermined intervals or to address water quality issues. The water treatment product 1 in the present embodiment is in the form of a solid. The water treatment product 1 may comprise flakes, granules or powder. In the present embodiment, the water treatment product 1 is a powder. In a variant, the water treatment product 1 could be a liquid. The water treatment product 1 comprises a flocculant (flocculating agent) for promoting flocculation of the particles dispersed in the water. Flocculation is the process whereby particles of a dispersion contact and adhere to each other, thereby forming larger floes (i.e. clusters of particles). The term flocculation is synonymous with agglomeration and coagulation/coalescence. The flocculant causes the particles dispersed in the water to form floes which can more readily be removed from the swimming pool. The flocculant thereby enables the removal of particles which would be difficult or impossible to remove through filtration alone.

The flocculant may comprise a suitable polyelectrolyte flocculant (cationic, non-ionic or anionic). The flocculant may comprise a multivalent cation, such as aluminium, iron, calcium or magnesium. The flocculant may have a positive electrical charge, thereby attracting and adhering to particles having a negative electrical charge. The flocculant cations may react with water to form insoluble hydroxides which may group into larger floes (i.e. clusters of particles). Alternatively, the flocculant may be organic, for example polyacrylamide. A suitable flocculant is aluminum sulfate which reacts with water to form a gelatinous precipitate of aluminum hydroxide under neutral or slightly-alkaline conditions. The flocculant may comprise polyaluminum chloride (PAC) having a general formula Al_nCI_(3n-m)(OH)_(m). The polyaluminum chloride may, for example, be Ali₂Cli2(OH)₂4_. Other modified PAC compounds include polyaluminum hydroxidechloride silicate (PACS) and polyaluminum hydroxidechloride silicate sulfate (PASS). Other suitable flocculants include one or more of the following: alum; aluminum sulfate; calcium oxide; iron chloride; iron sulfate; polyacrylamide; polyaluminum chloride; polyaluminum hydroxidechloride silicate sulfate; polyaluminum hydroxidechloride silicate; sodium aluminate; and sodium silicate. The flocculant in the present embodiment comprises polyaluminum chloride (PAC). In use, the polyaluminum chloride will floe the particles dispersed in the water.

The water treatment product 1 comprises a structural component which provides a seed or base to initiate formation of the floes. The structural component is at least substantially insoluble in water. The particles dispersed in the water may adhere to the structural component form the floes. The structural component in the present embodiment comprises cellulose. The cellulose may act as a flocculant. The cellulose provides a base for the water treatment product 1 and offers good flocculation properties. At least certain types of cellulose are biodegradable. A suitable cellulose is 2,3,6-Tricarboxylate Cellulose. The cellulose and the polyaluminum chloride are effective in floccing (agglomerating) the particles dispersed in the water. The resulting floes will initially sink to the bottom of the swimming pool.

The water treatment product 1 in the present embodiment also comprises Ethylenediaminetetraacetic acid (EDTA). The EDTA component of the water treatment product 1 functions as a metal binder and may sequester metal ions in aqueous solution, for example Ca²⁺ and Fe³⁺ ions. The EDTA will bind various heavy metals (copper/aluminum/iron/lead etc.) by chelating them. Advantageously, the EDTA may dissolve limescale in the swimming pool.

An oxidizing agent is provided in the water treatment product 1 to provide a non-chlorine shock in the swimming pool. A suitable shock oxidizer is potassium peroxymonosulfate, commonly known as potassium monopersulfate, which is present as a component of a triple salt with the formula 2KHS0₅-KHS0₄-K₂S0₄ potassium hydrogen peroxymonosulfate sulfate (5:3:2:2). A commercially available monopersulfate compound is Oxone (RTM). Other oxidizing agents may be used in the water treatment product 1 .

The water treatment product 1 in accordance with an aspect of the present invention comprises an active compound for generating a gas when the water treatment product 1 is introduced into water. The gas-producing compound in the present embodiment comprises or consists of sodium percarbonate having the formula 2Na₂G0₃-3H₂0₂. The sodium percarbonate dissolves in the water in the swimming pool to generate hydrogen peroxide which decomposes into water and oxygen. The reaction is as follows:

2Na₂C0₃ 3H₂0₂ 3H₂0₂ + 4Na⁺+ 2C0² ₃

H₂0₂ — 3H₂0 + 0₂

A catalyst may be provided to promote decomposition of the hydrogen peroxide into water and oxygen. The catalyst may be manganese dioxide or a salt of a metal such as iron, copper or lead. In a variant, the water treatment product 1 may comprise an addition compound of sodium carbonate and hydrogen peroxide for generating oxygen when added to water. The addition compound may be mixed with a water-soluble solid matter of manganese dioxide or salts of metal such as iron, copper, or lead to be used as a catalyst. A water-soluble binding agent may be used to bind the manganese dioxide or salts of metal. The solid matters may dissolve gradually over time thereby resulting in oxygen being generated over an extended time period. It will be understood that different compounds may be utilised, either for producing oxygen or other gases. The gas-producing compound reacts with the water and generates gas bubbles which rise to the surface of the water. In the present embodiment, the potassium mono persulfate and the sodium percarbonate produce oxygen. The bubbles are incorporated into, or adhere to, the floes of particles formed by the flocculant in the water treatment product 1 . The bubbles may, for example, be trapped interstitially between particles as they agglomerate to form the floes. The bubbles increase the buoyancy of the floes. At least in certain embodiments, the buoyancy is increased sufficiently to cause the floes to float to the surface of the swimming pool. The floes are then removed at or near the surface of the swimming pool. The floes may be removed using a suitable collection or skimming device. A skimmer forming part of the swimming pool filtration system may remove the floes, or they may be removed manually. A vacuum system could optionally be used to remove the floes at or near the surface of the swimming pool.

By way of example, the water treatment product 1 in accordance with the present embodiment has the following product:

The method of using the water treatment product 1 will now be described with reference to Figures 1 to 5. A swimming pool 2 containing water 3 is shown schematically in Figure 3. The swimming pool 2 comprises a treatment system (generally denoted by the reference numeral 4). The treatment system 4 comprises at least one skimmer 5, a pump 6, a multiport valve (MPV) 7 and at least one filter apparatus 8. The filtration system 4 comprises a waste outlet 9 connected to a waste line. A drain 10 is provided at the bottom of the swimming pool 2. The skimmer 5 is arranged to remove water from the surface of the swimming pool 2. The skimmer 5 may comprise one or more flaps or a weir system automatically to adjust to the water level in the swimming pool 3 (typically up to approximately 15cm) so only the top part of the water 3 is taken off the swimming pool 2. The skimmer 5 is connected to the pump 6 which pumps water from the swimming pool 2 to the filter apparatus 8. The multiport valve 7 is operable to adjust the fluid connection between the pump 6, the filter apparatus 8 and the waste outlet 9. The filter apparatus 8 may comprise any suitable filer media (not shown), such as sand, glass beads or the like. In the present embodiment the filter apparatus 8 comprises open cell filter media of the type described in International patent application WO 2016/185159 (EVOLUTION AQUA LIMITED), the contents of which are incorporated herein in their entirety by reference. The treatment system 4 may optionally include a sterilisation unit (not shown).

As shown schematically in Figure 2, the water 3 is contaminated by solid particles 11 (represented schematically by solid circles) which adversely affect the clarity of the water 3. The particles 11 may be dispersed throughout the water 3 and/or may be dispersed over the surface of the water 3 (for example dust particles that have been blown into the swimming pool 2). The filter apparatus 8 is operable to remove debris from the water 3 by mechanical filtration. The particles 11 may be sufficiently small to render them difficult to filter using conventional swimming pool filtration systems. As such, removal of the particles 11 from the swimming pool 2 may be difficult using the filter apparatus 8.

The pump 6 is deactivated to stop water being pumped from the swimming pool 2. The water treatment product 1 (represented schematically by triangles in the figures) is then added to the water 3. As shown in Figure 3, the water treatment product 1 may be distributed over the surface of the water 3. The flocculant in the water treatment product 1 dissolves in the water 3 and causes the particles 11 to agglomerate to form floes (represented schematically by dashed circles and denoted generally by the reference numeral 13). As illustrated in Figure 4, these floes are composed of a plurality of particles. The particles may be retained in the floes 13 by a binding agent or a gelling agent. The binding/gelling agent may be incorporated in the water treatment product 1 . Alternatively, the flocculant may react with water to form a gel suitable for retaining the particles in the floes 13. In the present embodiment, the flocculant comprises polyaluminum chloride (PAC) which reacts with the water 3 to form a gel which is suitable for binding the particles 11 together. Other binding agents or gelling agents are contemplated.

Due to their increased size, the floes 13 generally sink to the bottom of the swimming pool 2, as represented by the arrows in Figure 4. In the present case, the gas-producing compound is activated by water. The introduction of the water treatment product 1 into the swimming pool 2 activates the gas-producing compound and initiates the generation of oxygen. The oxygen generated by the gas-producing compound forms bubbles (represented schematically by open circles and denoted generally by the reference numeral 15). As shown in Figure 5, at least some of the oxygen bubbles 15 may bond to or adhere to the floes 13 of the particles 11 . The bubbles 15 may be introduced into the gel formed by the water treatment product 1 . The dispersed gas (oxygen in the present embodiment) provides an additional phase within the gel. The buoyancy of the floes 13 is thereby increased, i.e. the density of the floes 13 (which contain the gel) is reduced. The relative density of the floes 13 (to the water 3) is reduced to less than one (1) and the floes 13 float or rise in the water 3. The floes 13 rise to an upper region of the water 3 at or proximal to the surface of the swimming pool 2, as represented by the arrows shown in Figure 5. The particles 11 are trapped in the gel (or colloidal dispersion) formed by the water treatment product 1 and, at least in certain embodiments, may form a gel at or proximal to the surface of the swimming pool 2, as shown in Figure 6. A typical period of time for formation of the surface gel is one (1) hour from introduction of the water treatment product 1. As shown in Figure 5, the floes 13 may form a layer 16 on the surface of the swimming pool 3. The floes 13 can then be removed at or near the surface of the swimming pool 2 using a suitable collection device, such as a net, a skimmer or a pool cleaning vacuum. The floes 13 may conjoin or congeal with each other at the surface to form the layer 16. This may enable the surface layer 16 to be drawn from the surface of the swimming pool 2 using a skimmer. Thus, the particles 11 can be collectively removed from the swimming pool 2.

By including an active ingredient which generates a gas, the water treatment product 1 may be considered as an active flocculant. The water treatment product 1 agglomerates the particles 11 into floes 13. The resulting floes 13 are then displaced to the surface of the water 3 for collection and removal.

A block diagram 50 illustrating the method of treating the swimming pool 2 in accordance with an aspect of the present invention is shown in Figure 7. The pump 8 is deactivated (BLOCK 55). The water treatment product 1 is introduced into the swimming pool 2 (BLOCK 60). The flocculant in the water treatment product 1 reacts with the water 3 and causes the dispersed particles 11 to form floes 13 (BLOCK 65). The floes 13 initially fall in the water 3 and may settle on the bottom of the swimming pool 2 (BLOCK 70). The swimming pool 2 is not disturbed for a period of time, for example one (1) hour (BLOCK 75) in order to prevent or reduce disturbance of the floes 13. The oxygen-producing compound in the water treatment product 1 generates a gas (oxygen) which forms bubbles and reduces the relative density of the floes 13. The floes 13 rise to the surface of the swimming pool 2 forming a surface layer 16 (BLOCK 80). The multiport valve 7 is operated to connect the skimmer 5 to the discharge outlet 9, thereby bypassing the filter apparatus 8 (BLOCK 85). The multiport valve 7 may optionally be operated at any stage after introduction of the water treatment product 1 . The pump 8 is activated to pump water from the skimmer 5 to the discharge outlet 9 and to waste (BLOCK 90). When the surface layer 16 has been removed, the multiport valve 7 is operated to connect the skimmer 5 to the filter apparatus 8 (BLOCK 95). The treatment process is complete and the swimming pool 2 is ready for use (BLOCK 100). The floes 13 are then allowed to migrate to the top of the swimming pool 2. The main drain 10 may be closed and the pump 8 activated so that the water 3 is drawn from the swimming pool 3 only via the skimmer 5. The multiport valve 7 is configured to connect the skimmer 5 to waste so that the floes 13 (and any other debris) does not go to the filter apparatus 8 but is instead pumped directly to the waste outlet 9. Thus, the filter apparatus 8 is not contaminated by the particles 11 and floes 13. Thus, the need to clean the filter apparatus 8, for example by performing backwashing, may be reduced or avoided. The method does not result in a decrease in the flow rate through the filter apparatus 8 or an increase in operating pressure of the filter apparatus 8 (which may otherwise occur as a result of partial or complete blockage of the filter, for example in prior art arrangements in which the flocculant is introduced into the filter apparatus). The interval between cleaning (backwashing) operations on the filter media in the filter apparatus 8 may be extended. Alternatively, or in addition, there may be a reduced chance of channelling of the filter media (avoiding channels forming in the filter media along which the water may pass without being filtered)

The presence of microorganisms, bacteria and protozoa in swimming pools may pose a health risk. The parasitic alveolate Cryptosporidium is a particular problem in swimming pools that may cause respiratory and gastrointestinal illness. Cryptosporidium is spread by the release of oocysts in diarrhoea. If this happens in a swimming pool, these oocysts are extremely difficult to kill with chlorine and, due to their small size (between 4-6 microns), difficult to filter out of the water. The filter media used in most swimming pool filtration systems struggle to remove 4-6 micron particles. To counter this problem, polyaluminum chloride (PAC) is constantly added to the filtration system to remove oocysts from the pool water. PAC works by creating a gel like substance on the surface of the filter bed which will then be backwashed away down the drain. It is envisaged that the water treatment product 1 described herein may be used as part of a daily water treatment regime (before or after the swimming pool 2 is used for the day) may have benefits in removing Cryptosporidium from the water 3 in the swimming pool 2 more effectively than prior art techniques. It is believed that purging the floes 13 directly to waste may prove particularly effective.

Commercial pools have a set response for any "fecal" incident in the pool. This usually involves immediately closing the pool, raising the chlorine level to a predetermined level and filtering the water for 6 turnovers of the pool water (a turnover is when the complete volume of water in the pool has passed through the filter apparatus, each turnover may take four (4) hours). The filter apparatus is then backwashed and the water filtered for a further eight (8) hours. If the disinfection levels and the pH are acceptable, only then can the pool be opened, possibly thirty-two (32) hours after the initial contamination. It is envisaged that the water treatment product 1 according to the present invention could expedite this process. After a contamination event, the water treatment product 1 may be added and the resulting floes 13 discharged to waste. At least in certain embodiments, the amount of time that the swimming pool 2 is closed could be reduced considerable compared to the current operation. As described herein, bypassing the filter apparatus 8 can reduce the likelihood of the oocysts being retained in the filtration system 4.

The water treatment product 1 has been described herein with particular reference to the removal of particles 11 , which are typically an insoluble solid. It is envisaged that the water treatment product 1 may also be suitable for treatment of heterogeneous liquid dispersions, for example the removal of oil from water. In the case of swimming pools, oil may be introduced into the water 3 from associated mechanical and/or electromechanical devices, such as a counter-current unit or a motorised cover. It is known to use oil (typically vegetable oil) to hydraulically power turbines etc. which may leak. The removal of oil from the swimming pool 3 is extremely difficult. Other sources of liquid contamination in the swimming pool include sunscreen, body oils, etc.

In the present embodiment, the water treatment product 1 is in the form of a composition comprising or consisting of a mixture of the flocculant and the gas-producing compound. Instructions may be supplied with the water treatment product 1 to ensure that an appropriate dosage of the flocculant and gas-producing compound is used for treatment of a particular volume of water. The flocculant and gas-producing compound may be introduced into the swimming pool 2 as a single dose of the water treatment product 11 .

In a variant, the water treatment product 1 may comprise separate containers, packets or sachets of the flocculant and gas-producing compound. The flocculant and gas-producing compound may be included at an appropriate ratio in the containers, packets or sachets. The flocculant and gas-producing compound may be mixed prior to introduction into the swimming pool 2. The flocculant and the gas-producing compound may be mixed as solids, or they may be introduced into a container for mixing with water prior to introduction into the swimming pool. Alternatively, the flocculant and gas-producing compound may be introduced separately into the swimming pool 2, either sequentially or concurrently. The flocculant may be introduced before or after the gas-producing compound. The flocculant and gas-producing compound may be supplied together as a pack, for example in a carton or container. Appropriate instructions may be supplied with the water treatment product 1 to provide dosage rates and the like, for example to ensure that appropriate quantities of the flocculant and gas-producing compound are added to the swimming pool 2.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. The present invention has been described with reference to a gas-producing compound which generates oxygen. It will be understood that different gas-producing compounds may be utilised, either to generate oxygen or to generate other gases. For example, the gas-producing compound may generate carbon dioxide (CO2) or carbon monoxide (CO). In a variant of the embodiment described herein, the cellulose could be omitted.

The swimming pool 1 has been described herein with reference to a skimmer apparatus 5. In a variant, an overflow system (not shown) may be provided for removing water from the swimming pool 1 . The overflow system may be in liquid communication with a balance tank. The floes 11 may accumulate in the balance tank. The floes may subsequently be removed from the balance tank.

A water overflow may be provided on one or more sides of the swimming pool 3. The water from the surface of the swimming pool 3 flows into a collection trough and collects in the balance tank before being passed through filter apparatus. With an overflow system, water displaced by bathers in the swimming pool 3 is held by the balance tank and will return to the swimming pool 3 once the bathers have left and the water level lowers. After adding the water treatment product 1 , water could be added to the swimming pool 3 to cause the floes 13 to overflow into the balance tanks. The floes 13 would collect in the balance tank for removal. The floes 13 could be discharged directly to waste or removed from the balance tank.

The water treatment product 1 could be used in other applications. The water treatment product 1 could be used to treat drinking water. The water treatment product 1 could be used to reduce turbidity of the drinking water and also to remove harmful microorganisms, bacteria and protozoa. The water treatment product 1 could be used in conjunction with a disinfectant, such as calcium hypochlorite.

Claims

1 . A water treatment product comprising: a flocculant for aggregating particles dispersed in water to form floes; and a gas-producing compound for producing a gas to promote buoyancy of the floes formed by the flocculant.

2. A water treatment product as claimed in claim 1 , wherein the gas-producing compound comprises or consists of an oxygen-producing compound.

3. A water treatment product as claimed in claim 1 or claim 2, wherein the gas-producing compound comprises or consists of sodium percarbonate.

4. A water treatment product as claimed in any one of claims 1 , 2 or 3, wherein the gas- producing compound constitutes 10% to 40% by mass of the water treatment product.

5. A water treatment product as claimed in any one of the preceding claims comprising an oxidizer.

6. A water treatment product as claimed in claim 5, wherein the oxidizer comprises or consists of potassium monopersulfate.

7. A water treatment product as claimed in claim 5 or claim 6, wherein the oxidizer constitutes 1% to 10% by mass of the water treatment product.

8. A water treatment product as claimed in any one of the preceding claims wherein the flocculant comprises or consists of polyaluminum chloride.

9. A water treatment product as claimed in any one of the preceding claims, wherein the flocculant constitutes 50% to 75% by mass of the water treatment product.

10. A water treatment product as claimed in any one of the preceding claims, wherein the flocculant comprises or consists of cellulose.

11. A water treatment product as claimed in claim 10, wherein the cellulose constitutes 5% to 25% by mass of the water treatment product.

12. A water treatment product as claimed in any one of the preceding claims comprising ethylenediaminetetraacetic acid (EDTA).

13. A water treatment method comprising : introducing a water treatment product into water, the water treatment product comprising a flocculant and a gas-producing compound; the flocculant aggregating particles dispersed in the water to form floes, and the gas- producing compound producing a gas which promotes buoyancy of the floes; and removing the floes formed by the flocculant at or near the surface of the water.

14. A water treatment method comprising: introducing a flocculant to aggregate particles dispersed in the water to form floes; introducing a gas-producing compound to produce a gas which promotes buoyancy of the floes; and removing the floes formed by the flocculant at or near the surface of the water.

15. A water treatment method as claimed in claim 14, wherein the flocculant and the gas- producing compound are combined in a water treatment product as claimed in any one of claims 1 to 12.

16. A water treatment method as claimed in any one of claims 13, 14 or 15, wherein the method comprising skimming a surface of the water to remove the floes.

16. A water treatment method as claimed in claim 15, wherein a filtration system comprises a skimmer, wherein the skimmer is used to skim the surface of the water to remove the floes.

17. A water treatment method as claimed in claim 16, wherein the method comprises configuring the skimmer to discharge water to waste.

18. A water treatment method as claimed in any one of claims 13 to 18, wherein the gas- producing compound produces oxygen.

19. A water treatment method as claimed in any one of claims 13 to 18, wherein the water treatment method comprises treating water in a swimming pool.

20. A method of manufacturing a water treatment product, the method comprising mixing a flocculant and a gas-producing compound.