Flush block to remove micropollutants in flushing water

Abstract

The invention relates to a toilet block for the removal, destruction, degradation or mineralization of persistent micropollutants released in said toilets and as a consequence indirectly to remove such persistent micropollutants from sanitary waste before it is released in the natural environment.

Description

[0001] FLUSH BLOCK TO REMOVE MICROPOLLUTANTS IN FLUSHING WATER

[0002] Field of the Invention

[0003] The invention relates to 1) a flush water treatment block (flush block), WC block (also called toilet (rim) block), 2) to a system comprising such a block, and 3) to the use of same.

[0004] Background of the invention

[0005] Persistent micropollutants, particularly medicinal drugs, pose significant environmental challenges due to their resilience against conventional wastewater treatment processes. These compounds, often found in trace concentrations, can accumulate in aquatic ecosystems, leading to adverse ecological and human health effects. The presence of pharmaceuticals in wastewater is primarily attributed to anthropogenic activities, notably the consumption and subsequent excretion of pharmaceuticals by humans, as well as improper disposal practices, agricultural runoff, and effluents from pharmaceutical manufacturing [Basile et al. (2011) Industrial & Engineering Chemistry Research 50(14), 8389-84012011; Vukcevic (2023) Tekstilna Industrija 71(3), 4-12; Ortuzar et al. (2022) Frontiers in Microbiology, 13; Patel et al. (2019) Chem. Reviews 119(6), 3510-3673].

[0006] Conventional wastewater treatment plants (WWTPs) are designed to remove biodegradable organic matter and pathogens; however, they often fall short in effectively eliminating micropollutants such as pharmaceuticals. Studies have shown that these compounds can persist in treated effluents, entering natural water bodies and potentially disrupting aquatic life [Ortuzar et al. cited above; Wilkinson et al. (2017) Environmental Pollution 231, 954-970; Tambosi et al. (2010) Quimica Nova 33(2), 411-420]. For instance, non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics have been detected in surface waters and groundwater, raising concerns about their ecological impact and the development of antibiotic-resistant genes or antibiotic-resistant bacteria [Tambosi et al., cited above; Grochowicz et al. (2022) Polymers 14(10), 2080].The sources of pharmaceutical pollution are diverse. In addition to residential and healthcare-related waste, significant contributions come from agricultural practices, where veterinary drugs are used extensively [Timofeeva et al. (2020) E3s Web of Conferences 217, 09009; Attallah et al. (2016) ACS Sustainable Chemistry & Engineering 5(1), 133-145]. Moreover, the manufacturing sector's shift to countries with less stringent environmental regulations exacerbates the issue, leading to increased emissions of pharmaceutical contaminants [Beek et al. (2016) Environmental Toxicology and Chemistry 35(4), 823-835)]. The complexity of wastewater, which often contains a mixture of pharmaceuticals and their metabolites, complicates the assessment of their environmental fate and toxicity [Escher et al. (2011) Water Research 45(1), 75-92].

[0007] For instance, a technical challenge to degrade persistent micropollutants in the water of the toilet bowl (e.g. pharmaceutical pollutants in human urine) before it gets further diluted, is to provide a flush block or toilet block that can release sufficient reactants during flushing. A specific challenge is that degradation (>90%) should happen within several minutes before pollutants are diluted in the sewer line.

[0008] Depending on the properties of the chemicals used as active ingredients, compression / compaction issues often occur during the compression of the ingredients into toilet blocks, or a stability problem occurs by rinsing such blocks by each toilet flush.

[0009] Present invention solves these problems by providing a stable, long lasting effective solid flush block or toilet block for micropollutant degradation in flush water such as in a flushing toilet.

[0010] SUMMARY OF THE INVENTION

[0011] The invention relates to 1) a flush water treatment block (flush block), WC block (also called toilet (rim) block), 2) to a system comprising such a block, and 3) to the use of same.

[0012] It is comprised in the technical field of sanitizing products, to be applied onto the internal wall of sanitary appliances such as toilet bowls, bidet, washbasins, pissoirs or in devices in direct contact with flushing water for instance a flush tank.It concerns the field of the flush blocks or toilet blocks for treatment of micropollutants while flushing.

[0013] More particularly the invention relates to such flush block or toilet block comprising solids of different composition, metal salt to the organic acid and polymer blends providing controlled, simultaneous release of reactive components to achieve effective micropollutant degradation over a commercially viable product lifetime.

[0014] Such flush water treatment block, comprising a first solid component (a) and a second solid component (b), wherein components (a) and (b) are physically separate and combined in a single unit or it concerns a flush water treatment block holder wherein the first solid component (a) and a second solid component (b) are physically separate in the block or in the block holder.

[0015] The flush block or toilet blocks are demonstrated, yet after a multiplicity of flushing operations, to in situ destruct, degrade or mineralize persistent micropollutants released in said flush bowl.

[0016] As a consequence, they indirectly remove such persistent micropollutants from sanitary waste before it is released to the sewage system or in the natural environment.

[0017] Present invention solves a problem of micropollutant degradation in regular or sequential flush water by providing a solid, stable, erodible long-lasting, effective flush block or toilet rim block comprising solid, stable, erodible long-lasting, effective flush blocks of different composition for in situ micropollutant degradation in flush water. It provides a multi-component flush block or a toilet rim block that is physically stable over numerous flush cycles while ensuring a controlled, simultaneous release of both oxidant and catalyst in sufficient concentrations to achieve rapid degradation of micropollutants in the flushed water tank or the toilet bowl water.It was therefore an object of the present invention to provide a toilet (rim) block that is physically stable over numerous flush cycles while ensuring a controlled, simultaneous release of both oxidant and catalyst in sufficient concentrations to achieve rapid degradation of micropollutants in the toilet bowl water.

[0018] A solid, compressed, multi-component flush block or toilet block is developed or a flush block or toilet block with a plurality of compressed toilet blocks that is physically stable over numerous flush cycles while ensuring a controlled, simultaneous release of both oxidant and catalyst in sufficient concentrations to achieve rapid degradation of micropollutants in the toilet bowl water.

[0019] The claimed invention solves this problem in that the toilet (rim) block, comprises at least two discrete solids, such as discrete blocks, granules, pieces, tablets, pellets, beads or particles. Among these discrete solids are two types of solids, each such type of solid comprising 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof, 15-20 weight % of a hydrophilic compressible polymer, and 30-35 weight % of a hydrophobic compressible polymer. But the two types of solids are furthermore different in that the first type of discrete solid comprises solid hydrogen peroxide as active ingredient, and the second type of solid comprises as active ingredients an organic acid and iron(II) sulphate heptahydrate and / or ammonium iron(II) sulphate hexahydrate.

[0020] The claimed invention solves this problem in that the toilet (rim) block, comprises at least two discrete solids, such as discrete blocks, granules, pieces, tablets, pellets, beads or particles. Among these discrete solids are two types of a compressed component or, each such solid comprising 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof, 15-20 weight % of a hydrophilic compressible polymer, and 30-35 weight % of a hydrophobic compressible polymer, with the first type of compressed component comprising solid hydrogen peroxide as active ingredient, and the second type of compressed component comprising as active ingredients an organic acid and iron(II) sulphate heptahydrate and / or ammonium iron(II) sulphate hexahydrate.

[0021] This problem has also been solved when a flush block or toilet block cage holds at least two discrete toilet blocks, a first type and a second type. Each such type of rim block comprises 0.5-2 weight % of a fatty acid with a carbon chain in the range of15 to 22 carbon atoms or a salt or a glyceride thereof, 15-20 weight % of a hydrophilic compressible polymer, and 30-35 weight % of a hydrophobic compressible polymer. But the first type of rim block comprises solid hydrogen peroxide as active ingredient, while the second type of rim block comprises as active ingredients an organic acid and iron(II) sulphate heptahydrate and / or ammonium iron(II) sulphate hexahydrate.

[0022] Preferably the flush block or toilet block is or the toilet blocks are a long-lasting product that can withstand a minimum amount of toilet flushes, for instance 100 to 300 flushes, and on the other hand ensuring the block dissolves at the right rate to each time release sufficient reactants. Ensuring the block dissolves at the right rate is crucial. If it dissolves too quickly, it can lead to wastage and frequent replacements. If it dissolves too slow, insufficient degradation efficiency of the micropollutants might be obtained.

[0023] Another problem in the art is that active ingredients for persistent micropollutants degradation may react in the flush block or toilet block before release in the rinsing water.

[0024] Present invention provides a solution to these problems by the recipient formulation, keeping the reactive ingredients separate in different blocks and controlling the release rate by the formulation with specific polymers.

[0025] The present invention provides a solution for persistent micropollutants that are released from households or healthcare facilities by adding in an air space enclosure or an air space void of a fixture or guidance engaged with a wastewater release system a water treatment block, which comprises a composite block with separate block units, each block unit containing a distinct solid phase: (a) solid hydrogen peroxide, for instance urea hydrogen peroxide (UHP) or sodium percarbonate (SPC) as active ingredient and (b) a blend of an organic acid and a metal salt of for instance iron, cobalt, manganese, copper, nickel or zinc as active ingredients. Block is positioned in the air space enclosure or an air space void of a fixture or guidance engaged with the wastewater release system so that it only comes in contact with rinsing water each time water is flushed over it. For instance such wastewater treatment block can be a toilet block, a so called rim block, that is positioned in the toilet bowl so that it is not an in-cistern block that is continuously present in waterand only comes in contact with rinsing water when the toilet is flushed, whereby sufficient active ingredient is released for degradation of the persistent micropollutants in each flush.

[0026] The present invention thus provides a water treatment block, for instance a toilet block, which comprises (a) a first component in the form of a discrete portion from (b) a second component, wherein i) the first component (a) contains solid hydrogen peroxide as active ingredient and ii) the second component (b) contains a blend of an organic acid and a metal salt with changeable valence as active ingredients.

[0027] In an advantageous embodiment, the block according to the present invention further comprises that the metal to organic acid molar ratio is in a range between 9:1 to 7:3, hereby metal can be of the group consisting of iron, cobalt, copper, nickel and zinc. Moreover, metal salts can be in a hydrate form.

[0028] In one embodiment, the organic acid is anhydrous citric acid (CeHsCb), tartaric acid (C4H6O6), oxalic acid (C2H2O4), malic acid (C4H6O5) or a hydrate form of said organic acid.

[0029] In a practical embodiment, the block according to the present invention comprises that the metal salt with changeable valence is iron(II) sulphate heptahydrate and / or ammonium iron(II) sulphate hexahydrate.

[0030] In an embodiment is also provided that both the first component (a) and the second component (b) of this block further contain as recipient a blend of 1) a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) a polymer.

[0031] In an embodiment, the block has a first component (a) and the second component (b) further contains as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 0 to 80 weight %, preferably 20 - 50 weight % of polymer recipient.

[0032] In an embodiment, in the block the fatty acid is selected from the group consisting of pentadecanoate, palmitate, stearate, arachidate, behenate, margarate, nonadecanoate, eicosanoate, docosanoate, heneicosanoate, or a salt or a glycerideof said fatty acid. Hereby the stearate can be selected of the group consisting of a magnesium stearate, sodium stearate, stearic acid or calcium stearate.

[0033] In an embodiment, in the block the polymer recipient of the first component (a) is a polymer blend with a mass ratio of hydrophilic polymer to hydrophobic polymer in a range from 3:7 to 4:6.

[0034] In an embodiment, in the block the polymer recipient of the second component (b) has a mass ratio of hydrophilic polymer to hydrophobic polymer in the range from 0:10 to 7:3.

[0035] In an embodiment, in the block the polymer is a compressible polymer and each component is compressed or the water treatment block is a compressed block.

[0036] In an embodiment, in the block the compressible hydrophilic polymer is selected from the group consisting of pullulan (Pul), microcrystalline cellulose (MCC), hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (NaCMC), polyvinyl-pyrrolidone (PVP), hydrophilic polyethylene glycol (PEG), polyvinyl alcohol (PVA), chitosan, xanthan gum, a hydrophilic acrylic polymer or a mixture thereof.

[0037] In an embodiment, in the block the compressible hydrophobic polymer is ethyl cellulose (EC), polylactic acid (PLA), cellulose acetate (CAc), polyvinyl acetate (PVAc) or a mixture thereof.

[0038] With respect to the active ingredients controlling means and efficacy of destruction of the persistent micropollutants, it is noted that it is advantageous if these blocks are formed as follows. The block is characterised in that it is a single, solid piece of material comprising a plurality of two types of components. Or the block comprises a matrix or continuous phase binding the components or parts thereof together in one solid piece. Or the individual components in the block are organised so that each active ingredient remains exposed at the surface of the block after flushing removed part of the surface of said block. The block can be characterized in that at its surface it exposes a mosaic pattern of pieces of the distinct components. The block can be characterized in that it exposes parts of a component (a) and of a component (b) on its surface.In a practical embodiment, the block according to the present invention is a holder that holds the two types of compressed component. This holder may hold the two types of compressed component wherein the two types of compressed components remain separate in the holder. And in a particular embodiment this holder comprises openings, aperture or orifices, or the holder has a net structure so that rinsing water can pass over the separate components when flushing a toilet.

[0039] Usage in toilets or urinals. Potentially the block can also be used in other sanitary drains, such as those connected to wash-hand basins, washbasins, washbowls and other types of sinks that could be exposed to organic micropollutants or other types of pollutants with a health hazard or environmental concern.

[0040] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter.

[0041] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0042] The present invention provides a flush block or a flush block holder, which comprises at least two solids of different composition i) a first type of solid with solid hydrogen peroxide as active ingredient and ii) a second type of solid which contains a blend of an organic acid and a variable-valence metal salt as active ingredients.

[0043] In one aspect the invention provides that the block or a block holder according to is characterized in that in the first type of solid the hydrogen peroxide is urea hydrogen peroxide or sodium percarbonate or a combination thereof.

[0044] In a further aspect there is provided that the block or a block holder is characterized in that in the first type of solid the hydrogen peroxide is urea hydrogen peroxide. In a further aspect there is also provided that the block or a block holder is characterized in that in the second type of solid the metal to organic acid molar ratio is in a range between 9:1 to 7:3.

[0045] In a preferred aspect there is provided that the block or a block holder is characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 0 to 80 weight % of polymer recipient based on the total weight of each such solid.In another preferred aspect there is provided that the block or a block holder is characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 10 to 80 weight % of polymer recipient based on the total weight of each such solid.

[0046] In another preferred aspect there is provided that the block or a block holder is characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 20 - 50 weight % of polymer recipient based on the total weight of each such solid.

[0047] In another preferred aspect there is provided that the block or a block holder is characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 15-20 weight % of a hydrophilic compressible polymer, and 30-35 weight % of a hydrophobic compressible polymer based on the total weight of each such solid.

[0048] In addition, the block or a block holder according to the present invention may be characterized in that the first type of solid and the second solid are compressed. In a preferred aspect there is provided that this block or a block holder is characterized in that the first type of solid and the second solid are compressed with a force in the range of 10 to 350 MPa.

[0049] In addition, the block according to the present invention may be characterized in that that polymer recipient of first solid (a) is a polymer blend with a mass ratio of hydrophilic polymer to hydrophobic polymer in a range from 3:7 to 4:6, and wherein the polymer recipient of second solid (b) has a mass ratio of hydrophilic polymer to hydrophobic polymer in the range from 0:10 to 7:3.

[0050] In one aspect, the invention provides the block or a block holder according according to the present invention is characterized in that the weight ratio of the first solid to the second solid is from 1: 1 to 5: 1

[0051] In a preferred aspect there is provided that this block or a block holder is characterized in that the weight ratio of the first solid to the second solid is from 1:1 to 3:1

[0052] In yet another preferred aspect there is provided that this block or a block holder is characterized in that the weight ratio of the first solid to the second solid is from 2:1 to 5:1.It is another object of this invention to provide such a block or a block holder wherein the first solid comprises from 50% to 84% by weight of the combined weight of the first and second solid.

[0053] It is another object of this invention to provide such a block or a block holder that is characterized in that the variable-valence metal is at least one of iron, manganese, cobalt, copper, manganese, vanadium, chromium, cerium, nickel, zinc, molybdenum, and titanium.

[0054] It is another object of this invention to provide such a block or a block holder that is characterized in that the metal salt is of the group consisting of iron, cobalt, copper, manganese, nickel and zinc.

[0055] It is another object of this invention to provide such a block or a block holder that is characterized in that the variable-valence metal salt is iron(II) sulphate hexahydrate and / or ammonium iron(II) sulphate hexahydrate.

[0056] It is another object of this invention to provide such a block or a block holder wherein the organic acid is anhydrous citric acid (CeHsO?), tartaric acid (C4H6O6), oxalic acid (C2H2O4), malic acid (C4H6O5) or a hydrate form of said organic acid.

[0057] It is another object of this invention to provide such a block or a block holder wherein the fatty acid is selected from the group consisting of pentadecanoate, palmitate, stearate, arachidate, behenate, margarate, nonadecanoate, eicosanoate, docosanoate, heneicosanoate, or a salt or a glyceride of said fatty acid, and wherein the stearate is a magnesium stearate, sodium stearate, calcium stearate or a related compound like stearic acid.

[0058] It is another object of this invention to provide such a block or a block holder wherein the polymer is a compressible polymer and each solid is compressed or the water treatment block is a compressed block, and, wherein the compressible hydrophilic polymer is selected from the group consisting of pullulan (Pul), microcrystalline cellulose (MCC), hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (NaCMC), polyvinylpyrrolidone (PVP), crosslinked polyethylene glycol (PEG)-based polymers (PEG), polyvinyl alcohol (PVA), chitosan, xanthan gum, a hydrophilic acrylic polymer or a mixture thereof, and wherein the compressible hydrophobic polymer is polylactic acid (PLA), ethyl cellulose (EC), cellulose acetate (CAc), polyvinyl acetate (PVAc) or a mixture thereof.

[0059] Another aspect of the invention is a toilet that comprising a block or block holder as described above or as claimed, positioned in the toilet bowl so that it is not an incistern block that is continuously present in water and only comes in contact with rinsing water when the toilet is flushed.Another objective of this invention is to use of the block or block holder described above or as claimed, for in situ degradation of persistent micropollutants in flushing water.

[0060] DETAILED DESCRIPTION

[0061] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0062] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention.

[0063] Several documents are cited throughout the text of this specification. Each of the documents herein (including any manufacturer's specifications, instructions etc.) are hereby incorporated by reference; however, there is no admission that any document cited is indeed prior art of the present invention.

[0064] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0065] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.Moreover, the terms top, bottom, over, under and the like in the descriptions and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0066] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to the devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0067] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0068] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detaileddescription, with each claim standing on its own as a separate embodiment of this invention.

[0069] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0070] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0071] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only. Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are part of the description and are a further description and are in addition to the preferred embodiments of the present invention.

[0072] Each of the claims sets out a particular embodiment of the invention.

[0073] The following terms are provided solely to aid in the understanding of the invention.

[0074] Definitions

[0075] A toilet block, sanitary block, or toilet rim block, also sometimes called insert or cartridge is a small, often fragranced device placed inside the toilet bowl, usually but not necessarily under the rim, to help clean, deodorize, freshen with each flush. It is positioned so to be rinsed by the flushing water each the toilet gets flushed. The specific term "toilet block", "sanitary block" or "toilet rim block" is a species term of the genus term "flush block" which means such block that is rinsed by the flushingwater in an apparatus or systems designed for a multiplicity of flushing operations. In any part of the description the general term flush block can be substituted with: a toilet block, sanitary block, toilet block or toilet rim block.

[0076] In the present invention a flush block has been developed that is suitable for releasing reactants for the degradation of micropollutants in the rinsing water of a flush and in particular or releasing reactants for the degradation of persistent micropollutants in the rinsing water of a flush. It typically contains cleaning agents, fragrances, and sometimes colorants that release slowly into the water bowl, preventing buildup of limescale, bacteria, and odours. It is a flush-activated toilet insert that by a flush releases substances into the rinsing water.

[0077] Such flush block or toilet block of present invention can be a single, solid piece of material from multiple components or parts such to combine two or more distinct components with different chemical compositions wherein such individual components remain separate and distinct within the final structure they are organized in such that each different chemical composition is exposed at the surface of the single, solid piece of material. Optionally such composite flush block or toilet block can comprise a matrix or continuous phase that binds the multiple components or parts together in one solid piece. Such flush block or toilet block can be also a holder that holds multiple components of two or more different chemical compositions, the holder with openings, aperture or orifices, or the holder being a net so that rinsing water can pass over the separate components when flushing a toilet. Such block is not an in-cistern block that is continuously present in water. However, it comes in contact with rinsing water only when the toilet is flushed.

[0078] In-cistern blocks are toilet cleaning products designed to be placed directly inside the toilet cistern (the tank where water is stored before flushing). These blocks dissolve gradually in the cistern water.

[0079] A "block" as used herein refers to a block made by compressing the block material to form the block for instance in a tabletting machine. For example, the block material may be exposed to a punching means in a tabletting machine, compressing e.g. granules and / or powder to a gathered mass of pressed material. In the block of the present invention the distinguishing components that are a discrete portion from each other can be in the form of tablets.A "constitution" is understood as the composition or structure of the water treatment block, including the materials, active ingredients, and excipients that make up the formulation

[0080] A "variable-valence metal" is understood as a metal (usually a transition metal) that can reversibly switch between two or more oxidation states under the reaction conditions, and by doing so activates an oxidant (e.g., H2O2, persulfate, percarbonate, ozone, peracids) to generate reactive oxygen species (ROS) such as 'OH, SO4*”, 02’“, or1O2. Examples are Iron: Fe2+ / Fe3+in Fenton I photo-Fenton, activating H2O2 to make 'OH and regenerating Fe2+, Cobalt: Co2+ / Co3+activating peroxymonosulfate (PMS) or persulfate (PS) to form SC ’-(and sometimes ’OH), Manganese: Mn2+ / Mn3+ / Mn4+in heterogeneous catalysts that activate PMS / PS and can also promote oxygen radical pathways depending on pH / surface and Copper: Cu+ / Cu2+activating H2O2 or persulfates in certain system

[0081] In the present application, "discrete" means "separate, individually distinguishable units". For instance the discrete pieces, tablets, capsules or particles are separate unit doses you can count and physically separate. They are not a continuous mass / phase / melt itself or fused into one body. But they can be incorporated together in a toilet block (discrete solids in one toilet block) or can be comprised in the same rim block holder (discrete solids in one toilet block holder).

[0082] Persistent micropollutants in sanitary waste include a variety of chemicals and compounds that are resistant to degradation and can accumulate in the environment. These micropollutants are often introduced through various human activities, such as industrial processes, agricultural practices, medication and personal care products.

[0083] Persistent micropollutants enter the environment via toilets mainly after excretion via urine or faeces after consumption of pharmaceuticals, which are then flushed down the toilet, wherein these drugs or metabolites enter the wastewater systems or the environment directly. Unused or expired medications when flushed down the toilet may enter the wastewater system as direct disposal.Many personal care products like soaps, shampoos, and lotions contain micropollutants that can enter the environment through wastewater generated in a lavabo, shower or bath.

[0084] The block of present invention is particularly suitable for preventing the release of micropollutants and in particular persistent micropollutants in the environment from toilets. Toilets (including urinals for urination only), generally comprise a bowl with an air space and a tank or cistern holds the water that is used for flushing controlled volumes of water into the bowl. In the bowl, waste is collected before being flushed away. A curved section of the toilet generally holds a small amount of water to prevent sewer gases from escaping. It also helps create the siphon effect during flushing.

[0085] The block of present invention is suitable for household fixtures or industrial fixtures that are engaged with wastewater release systems, if such fixtures are designed with an air space enclosure to contain the block and with a flush system to flush controlled volumes of water over the block of present invention. Such fixture can for instance be a guidance with an air space void to hold the block of present invention. Such void only temporarily fills with sufficient water to contact the block after flushing with a dosed portion of water, wherein a tank or cistern holds the water. In case the water, that fills the air space void with a block of present invention, contains wastewater from household or industry, such fixtures with the block of present invention can prevent that chemicals that can persist in the environment, inadvertently end up in the water systems of our environment through improper disposal or spills.

[0086] Examples of such persistent micropollutants in sanitary waste are for instance pharmaceuticals and Personal Care Products (PCPs). Hereby are 1) antibiotics (e.g., ciprofloxacin, tetracycline) which can promote antibiotic resistance in bacteria, disrupting aquatic ecosystems by affecting microbial communities; 2) analgesics and anti-inflammatory drugs (e.g., ibuprofen, acetaminophen) that are toxic to aquatic life and may interfere with the endocrine systems of fish and other wildlife; 3) hormones (e.g., oestradiol, testosterone) which act as endocrine disruptors affecting reproductive health in wildlife, alter sex ratios and cause developmental issues in aquatic organisms; 4) antidepressants (e.g., fluoxetine) which induce behavioural changes in fish and other aquatic organisms and have potential for biomagnificationin food web and 5) cosmetics (e.g., parabens, phthalates) which act as hormonal disruptors in aquatic species and may lead to developmental and reproductive toxicity.

[0087] The presence of these persistent micropollutants in the environment can have severe consequences such as 1) ecosystem disruption, e.g. altering community structures and functions, leading to a loss of biodiversity; 2) water quality degradation, e.g. contaminating drinking water supplies, posing health risks to humans and wildlife; 3) bioaccumulation and biomagnification, e.g. some micropollutants can accumulate in organisms, leading to higher concentrations in top predators, including humans and 4) human health risks, e.g. chronic exposure to certain micropollutants is linked to various health issues, including hormonal imbalances, reproductive disorders, and increased cancer risk.

[0088] As an example, the formulation Sto.5%-EC3o%Pul2o%-UHP means that the block contains magnesium stearate (0.5 wt.% of the total mass), ethyl cellulose (30 wt.% of the total mass), pullulan (20 wt.% of the total mass), and UHP (accounting for the rest, resulting in a total percentage of 100%). The formulation Sto.s%-UHP means that the block contains magnesium stearate (0.5 wt.% of the total mass) and UHP (accounting for the rest, resulting in a total percentage of 100%). The formulation Sto.5%-EC2o%-Fe:CAi;5 contains magnesium stearate (0.5 wt.% of the total mass), ethyl cellulose (20 wt.% of the total mass), while the rest is iron(II) sulfate heptahydrate and citric acid monohydrate mixed in a molar ratio of 1:5. The formulation Sto.5%-EC2o%-AmFe:CA7;3 contains magnesium stearate (0.5 wt.% of the total mass), ethyl cellulose (20 wt.% of the total mass), while the rest is ammonium iron(II) sulfate hexahydrate and citric acid monohydrate mixed in a molar ratio of 7:3.

[0089] Optionally such composite flush block or toilet block can be contained in a block cage.

[0090] Magnesium stearate, if present in the composition of separate parts or units of the toilet block, is generally in an amount of about 0.2 to 2 wt.%, e.g. 0.6 to 2 wt.% or 0.5 to 1.75 wt.%, e.g. 0.6 wt.%, 0.75 wt.%, 1 wt.%, 1.25 wt.% or 1.5 wt.%, based on the total weight of the composition of such part or unit.Optionally, magnesium stearate is replaced by other hydrophobic, low soluble, nontoxic recipients, such as stearates. Examples of stearates include glyceryl stearate, magnesium stearate, sodium stearate, and calcium stearate; related compounds include stearic acid, stearyl fumarate, and sodium stearyl fumarate.

[0091] Optionally magnesium stearate is replaced by a saturated fatty acid, selected from saturated fatty acids with a carbon chain in the range of 15 to 22 carbon atoms such as pentadecanoic acid, palmitic acid, arachidic acid, behenic acid, margaric acid or derivates thereof such as glyceryl behenate, glyceryl margarate, glyceryl, glyceryl arachidonate, glyceryl palmitate, glyceryl 2-pentadecanoate or the salts of such fatty acids such as sodium pentadecanoate, magnesium pentadecanoate, sodium palmitate, calcium palmitate, sodium arachidate, calcium arachidate, sodium behenate, magnesium behenate, sodium margarate, calcium margarate, sodium nonadecanoate, sodium eicosanoate, sodium docosanoate and calcium heneicosanoate.

[0092] The addition of an organic acid in the block of present invention was found to improve the degradation rate of the block, while also having descaling abilities. Citric acid (CA) is the preferred organic acid in the composite toilet blocks of the present invention. Optionally, citric acid monohydrate may be replaced by citric acid anhydrous or citric acid dihydrate or other organic acids in anhydrous or hydrous form such as of the group consisting of acetic acid, lactic acid, ascorbic acid, tartaric acid, malic acid, fumaric acid, sorbic acid, benzoic acid, propionic acid, butyric acid, phytic acid, oxalic acid and acetylsalicylic acid. For the present invention, the preferred organic acids are anhydrous citric acid (CeHsO?), tartaric acid (C4H6O6), oxalic acid (C2H2O4) and malic acid (C4H6O5) and the monohydrate or dehydrate forms thereof.

[0093] Optionally ammonium iron(II) sulphate hexahydrate ((NH4)2SO4-Fe(SO4)-6H2O) can be replaced by another iron salt such as a compound of the group consisting of iron(II) sulphate heptahydrate (FeSO4-7H2O), ferrous gluconate, ferrous fumarate, ferrous lactate, ferrous citrate, ferrous ascorbate and ferrous tartrate. However, the preferred source of Fe2+is ammonium iron(II) sulphate ((NH4)2SO4-Fe(SO4)-6H2O) because it is more stable and resistant to oxidation in air compared with iron(II) sulphate heptahydrate (FeSO4-7H2O). The degradation catalysed by these two Fe2+salts did, however, not show a significant difference.Present invention demonstrates that a proportional blend of a compressible hydrophilic polymer with a compressible hydrophobic polymer provides a protective constitution preventing the active ingredients from being released too quickly or too much.

[0094] Optionally other compressible hydrophilic polymers can be used in the flush block or toilet block of the present invention than pullulan (Pul) and optionally other compressible hydrophobic polymers can be used than ethyl cellulose (EC). Pullulan can be replaced by a compressible hydrophilic polymer of the group consisting of microcrystalline cellulose (MCC), polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), chitosan, xanthan gum, hydroxyl (-OH) group modified cellulose derivatives, such as hydroxypropyl methylcellulose (HPMC) and sodium carboxymethyl cellulose (NaCMC), as well as crosslinked polyethylene glycol (PEG)-based polymers, or a blend of some of these. Ethyl cellulose (EC) can be replaced by a hydrophobic type of acrylic polymers (e.g., Eudragit types RS or RL) or by polylactic acid (PLA), cellulose acetate (CAc), polyvinyl acetate (PVAc) or a blend thereof.

[0095] We demonstrated that a higher ethyl cellulose (EC) content in the UHP block or units leads to a slower release rate of H2O2. As shown in Fig. 2, when soaked in 250 mL water for 10 min, the pure UHP block (0 wt.% EC content) was completely dissolved in one cycle. By increasing the EC content to 20 wt.%, the block was able to withstand two cycles, releasing 70% of H2O2 in the first cycle and about 30% of H2O2 in the second. Further increasing the EC content to 50 wt.% significantly lowered the release of H2O2 in each cycle to 14 ± 2%, and the block could withstand more than 4 cycles. Therefore, an EC content higher than 0 wt.%, for instance between 20 or 50 wt.% is preferred. For instance, in an example a formulation Sto.5%-ECso%-UHP was used for further testing.

[0096] The formulation above still suffered from the problem that the UHP block easily disintegrated upon touching after the test. To solve this, part of the EC was substituted by pullulan to increase the cohesion force of the block. A higher pullulan content resulted in a stickier appearance and a more integrated residual block while the H2O2 release was not significantly affected. As shown in Fig. 3, the use of 15-20 wt.% of Pul (with 35-30 wt.% of EC) resulted in a residual block that was integrated enough but not too sticky. The H2O2 release remained at a similar level. Therefore, aUHP formulation Sto.5%-EC3o%Pul2o%-UHP is a preferred formulation and was used for further experiments.

[0097] It was found with the Fe2+block or units, that a higher EC content resulted in a slower release rate of Fe2+, while the Fe2+:CA ratio (iron / citric acid molar ratio) did not have a significant influence on the release of Fe2+. As shown in Fig. 4, when no EC was added, the Fe2+ / CA block (molar ratio 1:5) was completely dissolved in 1 cycle (10 min soaking). By adding 20 wt.% of EC, the block could withstand more than 4 soaking cycles, releasing 18 ± 2% of Fe2+in each cycle. By changing the Fe2+:CA ratio from 1:5 to 2:1 (keeping 20 wt.% EC content), the release percentage remained at a similar level. Therefore, an EC content of 20 wt.% was selected for further testing. Consequently, the Fe2+block and UHP block were flushed together with 250 mL of Mili-Q water for 10 seconds to check the degradation performance for 100 mL of pollutant solution. As depicted in Fig. 5, The Fe2+block with no CA (Sto.s%-EC2o%-AmFe) could efficiently degrade various pollutants in 1 min. A second flush of the wet blocks after 40 min was also efficient. However, when placed in air for two days, the blocks were dried and the degradation in the third flush was much slower due to the oxidation of Fe2+to Fe3+on the block surface. A subsequent fourth flush of the wet blocks after 40 min improved the performance because of the dissolution of the outer Fe3+and the availability of fresh Fe2+. It can be concluded that the wet Fe2+block without an organic acid such as citric acid (CA) undergoes severe oxidation by air during long-term exposure to air.

[0098] To diminish this problem, CA was added to the formulation using different Fe2+:CA ratios (keeping 20 wt.% of EC). The blocks were tested following the same procedure as above. The degradation in the third flush (after drying the blocks in air for 2 days) is shown in Fig. 6. A conclusion can be drawn that a small quantity of CA improves the degradation by alleviating the Fe2+oxidation in air and accelerating the Fe2+regeneration in solution, but excess quantity results in reduced performance due to the reduced Fe2+concentration and undesired consumption of H2O2 by CA. The optimal Fe2+:CA ratio appeared between 9:1 to 7:3. Thus, Sto.5%-EC2o%-AmFe:CA7;3 (Fe2+:CA = 7:3) was selected for further tests.

[0099] EXAMPLESPreparation procedure and formulation design. Unless more specific or differently mentioned in the following examples the calculated amounts of ingredients were thoroughly ground in a mortar, transferred to a tablet die (020 mm), and compressed at 5 T (156 MPa) for 30 seconds. The final mass of the tablet was controlled to be 5.00 ± 0.01 g. For this example, the flush block or toilet block units were formulated with the recipients 1) magnesium stearate (0.5 wt.% of the total mass) and a polymer (either pullulan (Pul) or ethyl cellulose (EC) or a combination thereof) adjusted, e.g. to 25 wt.% of the total mass and with the active ingredient either urea hydrogen peroxide (UHP, CO(NH2)2-H2O2)), or Fe2+salt (ammonium iron(II) sulphate hexahydrate) with citric acid monohydrate. These separate flush block or toilet block units, either comprising UHP or Fe2+salt (ammonium iron(II) sulphate hexahydrate) with citric acid monohydrate, are combined as distinct solid phases (constituents) in a composite flush block or toilet block which composite thus comprises both 1) UHP and 2) Fe2+salt (ammonium iron(II) sulphate hexahydrate) with citric acid monohydrate but in separate constituents.

[0100] Example 1

[0101] To avoid the undesired consumption of H2O2 by Fe2+before being released into the solution, these two ingredients were separated into different blocks.

[0102] A block was formed comprising these different blocks as discrete portions of the block. So that the block comprised (a) a first component in the form of a discrete portion from (b) a second component. The first component (a) comprised urea hydrogen peroxide (UHP, CO(NH2)2-H2O2) or sodium percarbonate (SPC, Na2CO3-1.5H2O2) and the second component (b) comprised Fe2+and an organic acid. They are prepared separately and combined in use by each flush to release in the rinsing water the compounds that together act as reactants for the degradation of the persistent micropollutants. It was surprisingly found that as a source of H2O2, urea hydrogen peroxide (UHP, CO(NH2)2-H2O2) is shown to have a higher reaction rate constant than sodium percarbonate (SPC, Na2CO3-1.5H2O2). As shown in FIG. 1 (a graphic display that shows the first-order reaction rate constants for the degradation of carbamazepine (CBZ) by Fe2+ / sodium percarbonate (SPC, diamond grid bars) and Fe2+ / urea hydrogen peroxide (UHP, diagonal striped bars), where SPC and UHP were selected as the source of H2O2), SPC showed a significant prohibition effect at higher concentrations. By contrast, UHP worked in a broader concentration range with higher reaction rate constants. In this experimental set up thedegradation was tested using 100 mL of carbamazepine solution (start concentration: 50 pg / L) stirred at ambient temperature without pH adjustment. FeSO4-7H2O powder was added to the solution to reach the desired concentration of Fe2+(0.5-5 pM). Several seconds later, UHP or SPC powder was added to reach the desired concentration of H2O2(0.5-500 pM). The degradation started immediately. Samples (1.5 mL) were taken after 0, 0.5, 1, 2, 3 and 5 min, mixed with 0.1 mL of MeOH to stop the degradation, and analyzed by ultra-high performance liquid chromatography with diode array detection (UPLC-DAD). The degradation curve was fitted with the first-order reaction kinetics. Different ratios of Fe and H2O2were evaluated as shown in the figure.

[0103] As demonstrated in FIG. 1, UHP resulted in higher reaction rate constants than SPC, which showed a significant prohibition effect at higher concentrations ([Fe]: [H2O2] = 5 pM : 50pM and ([Fe] : [H2O2] = 5pM : 500 pM). By contrast, UHP worked in a broader concentration range with higher reaction rate constants ([Fe] : [H2O2] = 5 pM : 5 pM to [Fe] : [H2O2] = 5 pM : 500 pM). Both UHP and SPC can hence trigger the degradation of pollutant, but UHP has a better performance with wider applicable concentration range.

[0104] Example 2

[0105] The results of this example are demonstrated in FIG. 2 (a graphic display showing the effect of EC content (varying between 0 wt.%, 20 wt.% and 50 wt.%) on the H2O2release from 1-gram UHP blocks after different cycles of soaking).

[0106] The UHP blocks (Sto.s%-ECx-UHP, x= 0 / 20 / 50 wt.%) were prepared by compressing 1 gram ground mixture of magnesium stearate (0.5 wt.%), EC (0 / 20 / 50 wt.%) and UHP in a 013 mm die at 4 T force (296 MPa) for 30 s. The blocks were soaked in 250 mL of water, for 10 min in each cycle. There was a 30 min gap between two cycles. A sample of 3 mL was taken after 10 min of soaking, filtered by a 0.45 pm PTFE syringe filter, and measured by UV-Vis spectrophotometry (UV-Vis). The filtrate (10 pL) was mixed with 200 pL of acetic acid / ammonium acetate (1 M each) buffer, 1 mL of water and 1 mL of KI solution (containing 1 M of KI and 3 mM of ammonium molybdate tetra hydrate). The resulting absorbance was measured at 350 nm. The diagonal striped bars indicate the H2O2release after the first, second and third cycle of soaking, as shown in the legend. The diamond patterned bars indicate the release after the fourth cycle of soaking. As shown in Fig. 2, without EC (0 wt.% EC content), the UHP block was completely dissolved after one cycle. By increasing the EC content to 20 wt.%, the block was able to withstand two cycles of soaking, releasing 70% ofH2O2in the first cycle and about 30% of H2O2 in the second. Further increasing the EC content to 50 wt.% significantly lowered the release in each cycle to 14 ± 2% of H2O2, and the block could withstand more than 4 cycles. The polymer matrix EC is hence necessary to control the release, with a content higher than 0 wt.%, preferably in the range of 20-50 wt.% or higher.

[0107] Example 3.

[0108] UHP blocks (Sto.5%-ECxPuly-UHP, x + y = 50 wt.%) were prepared by compressing 1 gram ground mixture of magnesium stearate (0.5 wt.%), EC (30-50 wt.%), pullulan (0-20 wt.%) and UHP in a 013 mm die at 4 T force (296 MPa) for 30 s. Pullulan was added to increase the cohesion of the UHP block. For the soaking test, UHP blocks were soaked in 250 mL of water for 10 min and this was repeated 4 times with a 30 min time interval. The results of this example are demonstrated in FIG. 3. Herein in panel A (Fig. 3 A) a photo shows the effect of pullulan content on the appearance of the 1-gram UHP blocks slightly pressed after 4 cycles of 10-min soaking and in panel B (Fig. 3 B) a graphic showing the H2O2 release in each cycle. As shown in Fig. 3A, with a low content of pullulan (0-5 wt.%), the UHP tablets easily disintegrate after the soaking tests. By contrast, the use of 15-20 wt% of Pul (with 35-30 wt% of EC) resulted in residual blocks that were integrated enough but not too sticky. In panel B (Fig. 3 B), the diamond patterned bars indicate the release of H2O2 after the first cycle of soaking, the diagonal striped bars, after the second, third and fourth cycle of soaking, as shown in the legend. The release of H2O2 was insignificantly affected by pullulan content (2-25 wt.%), showing similar extents for different compositions.

[0109] Example 4.

[0110] The results of this example are demonstrated in FIG. 4 (a graphic showing the release of Fe2+from different 1-gram Fe2+blocks in 4 successive cycles of soaking). The blocks had different EC contents and molar ratios of Fe2+to citric acid (CA) as follows: left: Sto.5%-Fe:CAi:5(EC 0 wt.%, Fe2+:CA molar ratio 1:5), middle: Sto.5%-EC2o%-Fe:CAi;5(EC 20 wt.%, Fe2+:CA molar ratio 1:5), right: Sto.5%-EC2o%-Fe:CA2;i(EC 20 wt.%, Fe2+:CA molar ratio 2:1)). In this experiment citric acid monohydrate was added as a complexing agent to alleviate the oxidation of Fe2+. Iron(II) sulphate heptahydrate was used as the Fe2+source. The blocks were prepared by compressing 1 gram ground mixture of magnesium stearate, EC, iron(II) sulphate heptahydrateand citric monohydrate in a 013 mm die at 4 T force (296 MPa) for 30 s. The blocks were soaked in 250 mL of water, for 10 min in each cycle. There was a 30 min gap between two cycles. A sample of 5 mL was taken after 10 min of soaking, filtered by a 0.45 pm PTFE syringe filter, and measured by UV-Vis spectrophotometry (UV-Vis). The filtrate (3.2 mL) was mixed with 0.4 mL of acetic acid / ammonium acetate (1 M each) buffer, 0.2 mL of hydroxylamine hydrochloride (40 g / L), and 0.2 mL of 1,10-phenanthroline (2 g / L). The mixture was reacted for 15 min and the resulting absorbance was measured at 510 nm. The diagonal striped bars indicate the release of Fe2+after the first, second and third cycle of soaking, as shown in the legend. The diamond patterned bar, after the fourth cycle of soaking. As shown in Fig. 4, when no EC was added (left), the Fe2+ / CA block (molar ratio 1:5) was completely dissolved after 1 cycle. By adding 20 wt.% of EC (middle), the block could withstand more than 4 cycles, releasing 18 ± 2% of Fe2+in each cycle. By changing the Fe2+:CA ratio from 1:5 to 2:1 (keeping 20 wt.% EC content, right), the release percentage remained at a similar level. Therefore, an adequate EC content (e.g. 20 wt.%) is necessary to control the release of the block, and Fe2+:CA ratio mainly affects the degradation performance (discussed below) instead of the release rate of the block.

[0111] Example 5

[0112] The results of this example are demonstrated in FIG. 5 (a graphic display in 4 panels (Fig. 5 A, Fig. 5 B, Fig. 5 C and Fig. 5 D) that shows the degradation of a number of representative pollutants by flushing a 1-gram Fe2+block (without CA) together with a 1-gram UHP block) The UHP block was Sto.5%-EC3o%Pul2o%-UHP, and the Fe2+block was Sto.5%-EC2o%-AmFe (no CA, ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source). Both blocks were prepared by compressing a ground mixture of ingredients in a 013 mm die at 4 T force (296 MPa) for 30 s. For the degradation tests, the blocks were flushed two times with 250 mL of Mili-Q water for 10 s with a 40 min time interval, and then dried in air for 2 days, followed by two more flushes with a 40 min time interval. For each flush, the flushing water was immediately mixed with 100 mL of pollutant solution. The pollutant solution contained 7[3-estradiol (E2 □), 17o-ethinylestradiol (EE2 O), testosterone (TES A), progesterone (PROG V), sulfamethoxazole (SMX ), ciprofloxacin (CIP <), diclofenac (DCF >), and carbamazepine (CBZ O) with an initial concentration of 100 pg / L each. Samples (5 mL) were taken in the flushed solution at 0, 1, 3, 7, 10 min and filtered by 0.45 pm PTFE filter. One milliliter of the filtrate was mixed with 0.25 mL of quenching solution(containing 0.2 M of ascorbic acid) to stop the degradation and then measured by ultra-high performance liquid chromatography-diode array detection (UHPLC-DAD). The sample was analyzed on an Agilent Poroshell C18 column (1.9 pm, 02.1 mm x 50 mm) at ambient temperature at a flow rate of 0.3 mL / min. The mobile phases were formic acid / ammonium formate (10 mM each) in water (A) and acetonitrile (B). The percentage of acetonitrile in the mobile phase varied as follows: 5-11% (0-1 min), 11% (1-4.4 min), 15% (4.5-6.2 min), 35% (6.3-10.7 min), 50% (10.8-12 min), 95% (12.1-13 min), and 5% (13.1-14 min). Different wavelengths were used for the detection of E2 (285 nm), EE2 (285 nm), TES (285 nm), P4 (285 nm), SMX (285 nm), CIP (285 nm), DCF (285 nm) and CBZ (285 nm). The graphs demonstrate the reduction in concentration (C) of these pollutants with respect to their initial concentration (Co) as a function of degradation time. As shown in Fig. 5A, the first flush efficiently degraded all pollutants within 1 min. A second flush of the wet blocks after 40 min also degraded all pollutants within 1 min (Fig. 5B). When the blocks were subsequently dried in air for two days, degradation in the third flush was much lower due to the oxidation of Fe2+on the block surface (Fig. 5C). A subsequent fourth flush of the wet blocks after 40 min improved the performance because of the dissolution of the outer Fe3+and the availability of fresh Fe2+(Fig. 5D). It can be concluded that the oxidation of Fe2+during long-term air exposure was a severe problem, hindering the degradation performance when no organic acids were added.

[0113] Example 6

[0114] The results of this example are demonstrated in FIG. 6 (a graphic display in 6 panels (A to F) showing the effect of Fe2+:CA ratio on the degradation performance of a 1-gram Fe2+block after wetting and long-term drying).

[0115] The UHP block was Sto.5%-EC3o%Pul2o%-UHP, and the Fe2+block was Sto.s%-EC2o%-AmFe:CAx:y (x:y molar ratio ranging from 10:0 to 1:9, accounting for 79.5 wt.% in total, with ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source). All blocks were prepared by compressing 1 gram ground mixture of ingredients in a 013 mm die at 4 T force (296 MPa) for 30 s. For the degradation test, the UHP and Fe2+blocks were flushed twice with 250 mL of Mili-Q water for 10 s with a time interval of 40 min, and then left in air for 2 days until fully dried. The dried blocks were flushed a third time with 250 mL of Mili-Q water for 10 s. Only the third flush after drying was compared. The flushing water was immediately mixed with 100 mL of pollutantsolution. Samples were taken at 0, 1, 3, 7, 10 min, filtered with a 0.45 pm PTFE syringe filter, quenched with ascorbic acid and measured by UHPLC-DAD. The pollutant solution contained 7[3-estradiol (E2 □), 17o-ethinylestradiol (EE2 O), testosterone (TES A), progesterone (PROG V), sulfamethoxazole (SMX O), ciprofloxacin (CIP <), diclofenac (DCF >), carbamazepine (CBZ O) with an initial concentration of 100 pg / L each. From the figures, it can be deduced that increasing the quantity of CA from Fe2+:CA= 10:0 (Figure 6A) to Fe2+:CA= 9:1 (Figure 6B) and Fe2+:CA= 7:3 (Figure 6C) leads to an increasingly more efficient degradation of the pollutants within 1 min, by alleviating the Fe2+oxidation in air and accelerating the Fe2+regeneration in solution. However, a too-large quantity of CA, as shown in Figure 6D (Fe2+:CA= 5:5), Figure 6E (Fe2+:CA= 3:7) and Figure 6F (Fe2+:CA= 1:9), results in a reduced performance due to the reduced Fe2+concentration and undesired consumption of H2O2 by CA. The addition of CA in the Fe2+block significantly improved the long-term performance after drying, and the optimal Fe2+:CA ratio appeared between 9:1 to 7:3.

[0116] Example 7

[0117] The results of this example are displayed in Fig. 7 (a graphic displaying the effect of the water matrix on the degradation performance of a pair of 1-gram UHP and Fe2+blocks to better simulate real-world application conditions).

[0118] The UHP block was Sto.5%-ECi5%Pulio%-UHP, and the Fe2+block was Sto.s%-EC2o%-AmFe:CA7;3 (ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source). Both blocks were prepared by compressing 1 gram of a ground mixture of ingredients in a 013 mm die at 4 T force (296 MPa) for 30 s. The blocks were flushed together with 250 mL of water for 10 s. The flushing water was immediately mixed with 100 mL of pollutant solution containing gabapentin (GAB), carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), atenolol (ATL), venlafaxine (VEN), testosterone (TST), diclofenac (DCF), sertraline (SER), fluoxetine (FLX), escitalopram (ESC), ciprofloxacin (CIP) and clindamycin (CLD) with an initial concentration of 100 pg / L each. The matrix of the pollutant solution was either ultrapure water or synthetic urine with a composition of NaCI (30 mM), KCI (31 mM), CaCh (1.7 mM), NH4CI (24 mM), Na2SO4 (12 mM), MgSO4 (4.4 mM), trisodium citrate (2.4 mM), potassium oxalate (0.19 mM), NaH2PO4 (19 mM), Na2HPO4(4.7 mM), urea (250 mM), uric acid (1.5 mM) and creatinine (7.8 mM). As shown in the figure, almost complete removalof pollutants (99 ± 1%) was achieved in ultrapure water while synthetic urine only resulted in removal efficiencies around 10 ± 6%. This was mainly due to the presence of creatinine and uric acid which are typical urinary metabolites with strong radical scavenging properties. Therefore, higher release rates are needed to provide higher concentrations of reactants for the degradation.

[0119] Example 8

[0120] The results of example 8 are demonstrated in FIG. 8 (a graphic displaying the degradation performance of a pair of 1-gram UHP and Fe2+blocks, prepared with a reduced compression force to increase the release rate). The UHP block contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+block contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7;3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). Both blocks were prepared at a compression force of 0.5 T (37 MPa) by compressing 1 gram of ground mixture of ingredients in a 013 mm die for 30 s. The blocks were flushed together with 400 mL of tap water for 10 s and this was repeated every 5 min until the blocks completely disappeared. The flushing water was immediately mixed with 100 mL of 5-times diluted urine containing carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) with an initial concentration of 100 pg / L each. Samples were taken after 3 min, filtered by a 0.45 pm PTFE syringe filter, quenched with ascorbic acid and measured by UHPLC in combination with tandem mass spectrometry (MS / MS).

[0121] A typical dose of urine is around 0.3 L, and it will be diluted about 5 times by residual water in the toilet bowl (reaching around 1.5 L) before being mixed with flushing water (6 L). In the lab-scale tests, these ratios were mimicked by mixing 100 mL of 5-times diluted urine with 400 mL of flushing water. As shown in Fig. 8, the blocks could be flushed 14 times before completely disappearing. After two flushes, the chemical release and degradation reached a stable state, removing around 42 ± 4% of pollutants in each flush. After the 7thflush, the degradation performance gradually decreased until the last flush, which was mainly due to the shrinking of the block size and the concomitant lower chemical dosage released. Considering the tested blocks had a relatively low mass of 1 g, a longer flushing lifetime and higher degradation performance can be expected for larger blocks.

[0122] Example 9The results of this example is demonstrated in FIG. 9 (a graphic displaying the degradation performance of a pair of UHP and Fe2+blocks with a larger mass (3 g). The UHP block contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+block contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7:3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source)). The blocks were prepared by compressing 3 grams of ground mixture of ingredients in a 013 mm die for 30 s. The compression forces for the UHP and Fe2+blocks were adjusted to 0.5 and 1 T, respectively, to ensure both blocks had a similar durability during flushing. The blocks were flushed together with 400 mL of tap water for 10 s and this was repeated every 5 min until the blocks completely disappeared. The flushing water was mixed with 100 mL of 5-times diluted urine containing carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) with an initial concentration of 100 pg / L each. Samples were taken at 3 min, filtered by a 0.45 pm PTFE syringe filter, quenched with ascorbic acid and measured by UHPLC-MS / MS. As shown in the figure, the blocks could be flushed 16 times before completely disappearing. After the second flush, the chemical release and degradation reached a stable state, removing around 77 ± 3% of pollutants in each flush. After the 8thflush, the degradation performance gradually decreased due to the shrinking of the block size and lower chemical dosage released. With the higher mass of 3 grams, the blocks achieved higher degradation performances compared with the 1-gram blocks.

[0123] Example 10

[0124] The results of example 10 are demonstrated in FIG. 10 (a graphic displaying the degradation performance of a pair of 30-gram UHP and Fe2+blocks, which is the largest size available with the current lab-scale instrumentation). The UHP block contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+block contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7;3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). The blocks were prepared by compressing 30 grams of ground mixture of ingredients in a 034 mm die at 8 T force for 30 s. A compression force of 8 T was used to improve the durability of the tablets (see also Figure 11 below). The blocks were flushed together with 400 mL of tap water for 10 s and this was repeated every 5 min until the blocks completely disappeared. The flushing water was immediately mixed with 100 mL of 5-times diluted urinecontaining carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) with an initial concentration of 100 pg / L each. Samples were taken at 3 min, filtered by a 0.45 pm PTFE syringe filter, quenched with ascorbic acid and measured by UHPLC-MS / MS. As shown in the figure, the blocks could withstand 88 flushes. After the first flush, the chemical release and degradation reached a stable state, removing around 95 ± 2% of pollutants in each flush. After the 20thflush, the degradation performance gradually decreased due to the shrinking of the block sizes and the lower chemical dosage released. The overall performance supports the effectiveness of the blocks for reducing pharmaceutical pollutants in urine through toilet flushing.

[0125] Example 11

[0126] The results of example 11 are demonstrated in FIG. 11 (a graphic displaying the effect of compression force on the durability of 30-gram UHP and Fe2+blocks). The UHP blocks contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+blocks contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7;3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). All blocks were prepared by compressing 30 grams of ground mixture of ingredients in a 034 mm die for 30 s. The compression pressure ranged between 22 MPa (2 T) and 86 MPa (8 T). The blocks were flushed with 400 mL of tap water for 10 s and this was repeated every 5 min until completely disappearing. Durability was determined as the number of flushes the blocks could withstand. As shown in the figure, the durability of both UHP and Fe2+blocks could be adjusted by the compression pressure. Below 22 MPa (2 T), the Fe2+block was unable to form a compact structure, while increasing the compression pressure resulted in higher durability for both Fe2+and UHP blocks. With 86 MPa (8 T), the Fe2+block and UHP block achieved a similar durability (88 ± 1 flushes).

[0127] Example 12

[0128] The results of example 12 are demonstrated in FIG. 12 (a graphic displaying the effect of different acids in the Fe2+block on its degradation performance, with Fe2+blocks prepared with a mass of 5 gram). The Fe2+blocks were Sto.s%-FeX, with X representing the acid (KHSO4, citric acid monohydrate (CA) or tartaric acid (TA)) mixed in a Fe2+:acid molar ratio of 7:3 using iron(II) sulphate heptahydrate as the Fe2+source. The UHP block is represented by the formulation Sto.s%-UHP. All theblocks were prepared by compressing 5 grams of ground mixture of ingredients in a 020 mm die at 5 T force for 30 s. The blocks were flushed three times with 400 mL of water in 10 s with a time interval of 5 min, dried in air for 2 days, and flushed for a fourth time. For the third flush before drying and the fourth flush after drying, the flushing water was immediately mixed with 100 mL of 5-times diluted urine containing carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) with an initial concentration of 100 pg / L each. Samples were taken at 3 min after mixing, filtered by a 0.45 pm PTFE syringe filter, quenched with ascorbic acid and measured by UHPLC-MS / MS. From Figure 12, it is evident that without acid, the Fe2+block only achieved removal efficiencies around 72±5% and 15±6% before and after drying. By adding KHSO4, the removal efficiencies before drying were improved to around 90±4% but after drying the values decreased to 35±5%. In contrast, citric acid and tartaric acid largely improved the degradation performance, removing 96±4% and 95±1% before drying, and 64±5% and 67%±5% after drying, respectively. These organic acids form complexes with Fe2+and alleviate its oxidation in air, thus achieving improved performance after drying.

[0129] Example 13

[0130] The results of example 13 are demonstrated in FIG. 13 (a graphic displaying the effect of polymer content and type on the durability of UHP blocks with a mass of 5 grams). Two polymer matrices, microcrystalline cellulose (MCC) and a mixture of EC and pullulan (EC: Pul = 6:4 mass ratio), were tested. The UHP blocks (Sto.5%-Polymx-UHP, 0 < x < 25 (wt.%)) were prepared by compressing 5 grams of ground mixture of magnesium stearate (0.5 wt.%), polymer (MCC or EC / Pul mixture, 0-25 wt.%) and UHP in a 020 mm die at 5 T force for 30 s. The UHP blocks were flushed with 400 mL of tap water for 10 s and this was repeated every 5 min until the blocks completely disappeared. Durability is represented by the number of flushes the block could withstand before complete dissolution. The figure illustrates that the block durability depends on the polymer type and can be controlled by adjusting the polymer content. A mixture of EC and pullulan (with a mass ratio of EC: Pul = 6:4) provided a cohesive block and improved the durability of the UHP block. On the contrary, the use of MCC decreased the block durability.

[0131] Example 14The results of example 14 are demonstrated in FIG. 14 (a graphic displaying the effect of compression pressure on the durability of UHP blocks with a mass of 5 grams). The UHP blocks contained either 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) or 0 wt.% polymer (Sto.s%-UHP). The UHP blocks were prepared by compressing 5 grams of ground mixture of ingredients in a 020 mm die for 30 s. The compression pressure ranged between 31 MPa (1 T) to 156 MPa (5 T). The blocks were flushed with 400 mL of tap water for 10 s and this was repeated every 5 min until the blocks were completely dissolved. Durability is represented by the number of flushes that the blocks could withstand. As shown in the figure, the durability was independent of the compression pressure in the absence of polymer matrix but was steadily improved by increasing the pressure when 25 wt.% of polymer matrix was used.

[0132] BRIEF DESCRIPTION OF THE DRAWINGS

[0133] FIG. 1 is a graphic display that shows the first-order reaction rate constants for the degradation of carbamazepine (CBZ) by Fe2+ / sodium percarbonate (SPC, diamond grid bars) and Fe2+ / urea hydrogen peroxide (UHP, diagonal striped bars), where SPC and UHP were selected as the source of H2O2. The degradation was tested as explained in Example 1. In this FIG. 1, UHP is shown to result in higher reaction rate constants than SPC, which shows a significant prohibition effect at higher concentrations ([Fe] : [H2O2] = 5 pM : 50pM and ([Fe] : [H2O2] = 5pM : 500 pM). By contrast, UHP works in a broader concentration range with higher reaction rate constants ([Fe] : [H2O2] = 5 pM : 5 pM to [Fe] : [H2O2] = 5 pM : 500 pM). Both UHP and SPC can hence trigger the degradation of pollutant, but UHP has a better performance with wider applicable concentration range.

[0134] FIG. 2 is a graphic display showing the effect of EC content (varying between 0 wt.%, 20 wt.% and 50 wt.%) on the H2O2 release from 1-gram UHP blocks after different cycles of soaking. This demonstrates the results of Example 2. The diagonal striped bars indicate the H2O2 release after the first, second and third cycle of soaking, as shown in the legend. The diamond patterned bars indicate the release after the fourth cycle of soaking. As shown in Fig. 2, without EC (0 wt.% EC content), the UHP block was completely dissolved after one cycle. By increasing the EC content to 20 wt.%,the block was able to withstand two cycles of soaking, releasing 70% of H2O2 in the first cycle and about 30% of H2O2 in the second. Further increasing the EC content to 50 wt.% significantly lowered the release in each cycle to 14 ± 2% of H2O2, and the block could withstand more than 4 cycles. The polymer matrix EC is hence necessary to control the release, with a content higher than 0 wt.%, preferably in the range of 20-50 wt.% or higher.

[0135] FIG. 3 demonstrates the results of Example 3. In panel A (Fig. 3 A) a photo shows the effect of pullulan content on the appearance of the 1-gram UHP blocks slightly pressed after 4 cycles of 10-min soaking and in panel B (Fig. 3 B) a graphic shows the H2O2 release in each cycle. As shown in Fig. 3A, with a low content of pullulan (0-5 wt.%), the UHP tablets easily disintegrate after the soaking tests. By contrast, the use of 15-20 wt% of Pul (with 35-30 wt% of EC) resulted in residual blocks that were integrated enough but not too sticky. In panel B (Fig. 3 B), the diamond patterned bars indicate the release of H2O2 after the first cycle of soaking, the diagonal striped bars, after the second, third and fourth cycle of soaking, as shown in the legend. The release of H2O2 was insignificantly affected by pullulan content (2-25 wt.%), showing similar extents for different compositions.

[0136] FIG. 4 is a graphic showing the release of Fe2+from different 1-gram Fe2+blocks in 4 successive cycles of soaking of the experiment described in Example 4. The blocks had different EC contents and molar ratios of Fe2+to citric acid (CA) as follows: left: Sto.5%-Fe:CAi;5 (EC 0 wt.%, Fe2+:CA molar ratio 1:5), middle: Sto.5%- C2o%-Fe:CAi:5(EC 20 wt.%, Fe2+:CA molar ratio 1:5), right: Sto.5%-EC2o%-Fe:CA2;i(EC 20 wt.%, Fe2+:CA molar ratio 2:1). The diagonal striped bars indicate the release of Fe2+after the first, second and third cycle of soaking, as shown in the legend. The diamond patterned bar, after the fourth cycle of soaking. As shown in Fig. 4, when no EC was added (left), the Fe2+ / CA block (molar ratio 1:5) was completely dissolved after 1 cycle. By adding 20 wt.% of EC (middle), the block could withstand more than 4 cycles, releasing 18 ± 2% of Fe2+in each cycle. By changing the Fe2+:CA ratio from 1:5 to 2:1 (keeping 20 wt.% EC content, right), the release percentage remained at a similar level. Therefore, an adequate EC content (e.g. 20 wt.%) is necessary to control the release of the block, and Fe2+:CA ratio mainly affects the degradation performance (discussed below) instead of the release rate of the block.FIG. 5 is a graphic display that shows the results of Example 5. In 4 panels (Fig. 5 A, Fig. 5 B, Fig. 5 C and Fig. 5 D) it shows the degradation of a number of representative pollutants by flushing a 1-gram Fe2+block (without CA) together with a 1-gram UHP block. The UHP block was Sto.s%-EC3o%Pul2o%-UHP, and the Fe2+block was Sto.5%-EC2o%-AmFe (no CA, ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source). The pollutant solution contained 7[3-estradiol (E2 □), 17o-ethinylestradiol (EE2 O ), testosterone (TES A), progesterone (PROG V), sulfamethoxazole (SMX ), ciprofloxacin (CIP <), diclofenac (DCF >), and carbamazepine (CBZ O) with an initial concentration of 100 pg / L each. Samples (5 mL) were taken in the flushed solution at 0, 1, 3, 7, 10 min and filtered by a 0.45 pm PTFE filter. As shown in Fig. 5A, the first flush efficiently degraded all pollutants within 1 min. A second flush of the wet blocks after 40 min also degraded all pollutants within 1 min (Fig. 5B). When the blocks were subsequently dried in air for two days, degradation in the third flush was much lower due to the oxidation of Fe2+on the block surface (Fig. 5C). A subsequent fourth flush of the wet blocks after 40 min improved the performance because of the dissolution of the outer Fe3+and the availability of fresh Fe2+(Fig. 5D). It can be concluded that the oxidation of Fe2+during long-term air exposure was a severe problem, hindering the degradation performance when no organic acids were added.

[0137] FIG. 6 is a graphic display that shows the results of Example 6. In 6 panels (A to F) the effect of Fe2+:CA ratio are demonstrated on the degradation performance of a 1-gram Fe2+block after wetting and long-term drying. The UHP block was Sto.5%-EC3o%Pul2o%-UHP, and the Fe2+block was Sto.5%-EC2o%-AmFe:CAx;y(x:y molar ratio ranging from 10:0 to 1:9, accounting for 79.5 wt.% in total, with ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source). The pollutants contained in the solution each are shown in the graphic by following symbols: 7[3-estradiol (E2 □), 17o-ethinylestradiol (EE2 O), testosterone (TES A), progesterone (PROG V), sulfamethoxazole (SMX ), ciprofloxacin (CIP <), diclofenac (DCF >), carbamazepine (CBZ O). They had an initial concentration of 100 pg / L each. From the figures, it can be deduced that increasing the quantity of CA from Fe2+:CA= 10:0 (Figure 6A) to Fe2+:CA= 9:1 (Figure 6B) and Fe2+:CA= 7:3 (Figure 6C) leads to an increasingly more efficient degradation of the pollutants within 1 min, by alleviating the Fe2+oxidation in air and accelerating the Fe2+regeneration in solution. However, a too-large quantity of CA, as shown in Figure 6D (Fe2+:CA= 5:5), Figure 6E (Fe2+:CA= 3:7) and Figure 6F (Fe2+:CA= 1:9), results in a reduced performance dueto the reduced Fe2+concentration and undesired consumption of H2O2 by CA. The addition of CA in the Fe2+block significantly improved the long-term performance after drying, and the optimal Fe2+:CA ratio appeared between 9:1 to 7:3.

[0138] Fig. 7 is a graphic display of the results of example 7. It displays the effect of the water matrix on the degradation performance of a pair of 1-gram UHP and Fe2+blocks to better simulate real-world application conditions. The UHP block was Sto.5%-ECI5%PUIIO%-UHP, and the Fe2+block was Sto.5%-EC2o%-AmFe:CA7;3 (ammonium iron(II) sulphate hexahydrate (AmFe) as the Fe2+source).

[0139] The flushing water was immediately mixed with 100 mL of pollutant solution containing gabapentin (GAB), carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), atenolol (ATL), venlafaxine (VEN), testosterone (TST), diclofenac (DCF), sertraline (SER), fluoxetine (FLX), escitalopram (ESC), ciprofloxacin (CIP) and clindamycin (CLD) with an initial concentration of 100 pg / L each. The removal efficiency of each of these pollutants in ultrapure water or in synthetic urine has in the graphic for each pollutant a distinct grid bar (as displayed in this figure). As shown in the figure, almost complete removal of pollutants (99 ± 1%) was achieved in ultrapure water while synthetic urine only resulted in removal efficiencies around 10 ± 6%. This was mainly due to the presence of creatinine and uric acid which are typical urinary metabolites with strong radical scavenging properties. Therefore, higher release rates are needed to provide higher concentrations of reactants for the degradation.

[0140] FIG. 8 is a graphic display of the results of example 8. It demonstrates the degradation performance of a pair of 1-gram UHP and Fe2+blocks, prepared with a reduced compression force to increase the release rate. The pollutants carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) each have in this graphics a distinct symbol. As shown in Fig. 8, the blocks could be flushed 14 times before completely disappearing. After two flushes, the chemical release and degradation reached a stable state, removing around 42 ± 4% of pollutants in each flush. After the 7thflush, the degradation performance gradually decreased until the last flush, which was mainly due to the shrinking of the block size and the concomitant lower chemical dosage released. Considering the tested blocks had a relatively low mass of 1 g, alonger flushing lifetime and higher degradation performance can be expected for larger blocks.

[0141] FIG. 9 is a graphic display of the results of example 9. It demonstrates the degradation performance of a pair of UHP and Fe2+blocks with a larger mass (3 g). The UHP block contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+block contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7:3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). As shown in the figure, the blocks could be flushed 16 times before completely disappearing. After the second flush, the chemical release and degradation reached a stable state, removing around 77 ± 3% of pollutants in each flush. After the 8thflush, the degradation performance gradually decreased due to the shrinking of the block size and lower chemical dosage released. With the higher mass of 3 grams, the blocks achieved higher degradation performances compared with the 1-gram blocks.

[0142] FIG. 10 is a graphic display of the results of example 10. It is a graphic displaying the degradation performance of a pair of 30-gram UHP and Fe2+blocks, which is the largest size available with the current lab-scale instrumentation. The UHP block contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+block contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7;3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). Each pollutant in the graphic carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) is displayed by a different symbol. After the first flush, the chemical release and degradation reached a stable state, removing around 95 ± 2% of pollutants in each flush. After the 20thflush, the degradation performance gradually decreased due to the shrinking of the block sizes and the lower chemical dosage released. The overall performance supports the effectiveness of the blocks for reducing pharmaceutical pollutants in urine through toilet flushing.

[0143] FIG. 11 is a graphic display of the results of example 11. This graphic demonstrates the effect of compression force on the durability of 30-gram UHP and Fe2+blocks. The UHP blocks contained 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) and the Fe2+blocks contained 20 wt.% polymer (Sto.5%-EC2o%-AmFe:CA7:3, Fe2+:CA = 7:3, ammonium iron(II) sulphate hexahydrate as the Fe2+source). The UHP block in the graphic has the triangle symbol and the Fe2+block has a circle symbol. As shown in the figure, the durability of both UHP and Fe2+blocks could be adjusted by thecompression pressure. Below 22 MPa (2 T), the Fe2+block was unable to form a compact structure, while increasing the compression pressure resulted in higher durability for both Fe2+and UHP blocks. With 86 MPa (8 T), the Fe2+block and UHP block achieved a similar durability (88 ± 1 flushes).

[0144] FIG. 12 is a graphic display of the results of example 12. It demonstrates the effect of different acids in the Fe2+block on its degradation performance, with Fe2+blocks prepared with a mass of 5 gram. The Fe2+blocks were Sto.s%-FeX, with X representing the acid (KHSC , citric acid monohydrate (CA) or tartaric acid (TA)) mixed in a Fe2+:acid molar ratio of 7:3 using iron(II) sulphate heptahydrate as the Fe2+source. The UHP block is represented by the formulation Sto.s%-UHP. The bars display the removal efficiency of each pollutant, carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), venlafaxine (VEN), escitalopram (ESC), and clindamycin (CLD) by a different grid (as shown in this bar graphic)

[0145] From Figure 7, it is evident that without acid, the Fe2+block only achieved removal efficiencies around 72±5% and 15±6% before and after drying. By adding KHSC , the removal efficiencies before drying were improved to around 90±4% but after drying the values decreased to 35±5%. In contrast, citric acid and tartaric acid largely improved the degradation performance, removing 96±4% and 95±1% before drying, and 64±5% and 67%±5% after drying, respectively. These organic acids form complexes with Fe2+and alleviate its oxidation in air, thus achieving improved performance after drying.

[0146] FIG. 13 is a graphic display of the results of example 13. It demonstrates the effect of polymer content and type on the durability of UHP blocks with a mass of 5 grams. Two polymer matrices, microcrystalline cellulose (MCC) and a mixture of EC and pullulan (EC: Pul = 6:4 mass ratio), were tested. Durability is represented by the number of flushes the block could withstand before complete dissolution. The figure illustrates that the block durability depends on the polymer type and can be controlled by adjusting the polymer content. A mixture of EC and pullulan (with a mass ratio of EC:Pul = 6:4) provided a cohesive block and improved the durability of the UHP block. On the contrary, the use of MCC decreased the block durability.

[0147] FIG. 14 is a graphic display of the results of example 13. It demonstrates the effect of compression pressure on the durability of UHP blocks with a mass of 5 grams. TheUHP blocks contained either 25 wt.% polymer (Sto.5%-ECi5%Pulio%-UHP) or 0 wt.% polymer (Sto.s%-UHP). Durability is represented by the number of flushes that the blocks could withstand. As shown in the figure, the durability was independent of the compression pressure in the absence of polymer matrix but was steadily improved by increasing the pressure when 25 wt.% of polymer matrix was used.

Claims

FLUSH BLOCK TO REMOVE MICROPOLLUTANTS IN FLUSHING WATERClaims1. A flush block or a flush block holder, which comprises at least two solids of different composition i) a first type of solid with solid hydrogen peroxide as active ingredient and ii) a second type of solid which contains a blend of an organic acid and a variable-valence metal salt as active ingredients.

2. The block or a block holder according to any claim 1, characterized in that in the first type of solid the hydrogen peroxide is urea hydrogen peroxide or sodium percarbonate or a combination thereof.

3. The block or a block holder according to any one of the claims 1 to 2, characterized in that in the first type of solid the hydrogen peroxide is urea hydrogen peroxide.

4. The block or a block holder according to any one of the claims 1 to 3, characterized in that in the second type of solid the metal to organic acid molar ratio is in a range between 9:1 to 7:3.

5. The block or a block holder according to any one of the claims 1 to 4, characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 0 to 80 weight % of polymer recipient based on the total weight of each such solid.

6. The block or a block holder according to any one of the claims 1 to 4, characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 10 to 80 weight % of polymer recipient based on the total weight of each such solid.

7. The block or a block holder according to any one of the claims 1 to 4, characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain in the range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 2) 20 - 50 weight % of polymer recipient based on the total weight of each such solid.

8. The block or a block holder according to any one of the claims 1 to 4, characterized in that the first type of solid and the second solid further contain as recipient a blend of 1) 0.5-2 weight % of a fatty acid with a carbon chain inthe range of 15 to 22 carbon atoms or a salt or a glyceride thereof and 15-20 weight % of a hydrophilic compressible polymer, and 30-35 weight % of a hydrophobic compressible polymer based on the total weight of each such solid.

9. The block or a block holder according to any one of the claims 1 to 8, characterized in that the first type of solid and the second solid are compressed.

10. The block or a block holder according to any one of the claims 1 to 8, characterized in that the first type of solid and the second solid are compressed with a force in the range of 10 to 350 MPa.

11. The block according to any one of claims 1 to 10, wherein the polymer recipient of first solid (a) is a polymer blend with a mass ratio of hydrophilic polymer to hydrophobic polymer in a range from 3:7 to 4:6, and wherein the polymer recipient of second solid (b) has a mass ratio of hydrophilic polymer to hydrophobic polymer in the range from 0:10 to 7:3.

12. The block or a block holder according to any one of the claims 1 to 11, characterized in that the weight ratio of the first solid to the second solid is from 1:1 to 5:

113. The block or a block holder according to any one of the claims 1 to 11, characterized in that the weight ratio of the first solid to the second solid is from 1:1 to 3:

114. The block or a block holder according to any one of the claims 1 to 11, characterized in that the weight ratio of the first solid to the second solid is from 2:1 to 5:1.

15. The block or a block holder according to any one of the claims 1 to 11, wherein the first solid comprises from 50% to 84% by weight of the combined weight of the first and second solid.

16. The block or a block holder according to any one of the claims 1 to 15, characterized in that the variable-valence metal is at least one of iron, manganese, cobalt, copper, manganese, vanadium, chromium, cerium, nickel, zinc, molybdenum, and titanium.

17. The block or a block holder according to claims 1 to 15, characterized in that the metal salt is of the group consisting of iron, cobalt, copper, manganese, nickel and zinc.

18. The block or a block holder according to claims 1 to 15, characterized in that the variable-valence metal salt is iron(II) sulphate hexahydrate and / or ammonium iron(II) sulphate hexahydrate.

19. The block or a block holder according to claims 1 to 18, wherein the organic acid is anhydrous citric acid (CeHsCb), tartaric acid (C4H6O6), oxalic acid (C2H2O4), malic acid (C4H6O5) or a hydrate form of said organic acid.

20. The block or a block holder according to claims 1 to 19, wherein the fatty acid is selected from the group consisting of pentadecanoate, palmitate, stearate, arachidate, behenate, margarate, nonadecanoate, eicosanoate, docosanoate, heneicosanoate, or a salt or a glyceride of said fatty acid, and wherein the stearate is a magnesium stearate, sodium stearate, calcium stearate or a related compound like stearic acid.

21. The block or a block holder according to any one of claims 1 to 20, wherein the polymer is a compressible polymer and each solid is compressed or the water treatment block is a compressed block, and, wherein the compressible hydrophilic polymer is selected from the group consisting of pullulan (Pul), microcrystalline cellulose (MCC), hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (NaCMC), polyvinylpyrrolidone (PVP), crosslinked polyethylene glycol (PEG)-based polymers (PEG), polyvinyl alcohol (PVA), chitosan, xanthan gum, a hydrophilic acrylic polymer or a mixture thereof, and wherein the compressible hydrophobic polymer is polylactic acid (PLA), ethyl cellulose (EC), cellulose acetate (CAc), polyvinyl acetate (PVAc) or a mixture thereof.

22. A toilet comprising a block or block holder according to any one of claims 1 to 21, positioned in the toilet bowl so that it is not an in-cistern block that is continuously present in water and only comes in contact with rinsing water when the toilet is flushed.

23. Use of the block or block holder according to any one of claims 1 to 21, for in situ degradation of persistent micropollutants in flushing water.

Images