Process for bacteriostatic treatment of water

Abstract

A process for the treatment of water is provided comprising an introducing step into the water of a treatment compound comprising one or more zinc salts and carbonate-hydroxyapatite at least partially doped with Zn2+ ions.

Description

[0001] DESCRIPTION

[0002] PROCESS FOR BACTERIOSTATIC TREATMENT OF WATER

[0003] The present invention has as its object a process for the treatment of water of the type specified in the preamble of the first claim.

[0004] In particular, the process is configured to treat water by appropriately arresting the growth of bacteria and their reproduction and in particular reducing the bacterial load of said water. It can be used both in clear water (such as that of rivers, springs, lakes, stagnant water, storage water) and wastewater (also called discharge water), that is water deriving from use in human, domestic, industrial or agricultural activities and which, for this reason, has a bacterial load that can cause damage to health and to the environment.

[0005] As is known, the treatment of water both for its subsequent use and for its correct disposal is particularly relevant.

[0006] A first example occurs for wastewater, that is aqueous liquid substances that are produced by various human activities, both at industrial level and at agricultural level and also domestic. These waters, before returning to the sea or to rivers, require purification since during the various activities they have been contaminated and therefore contain a quantity of substances harmful to the environment and consequently to humans. Wastewater is mainly divided into black water and gray water.

[0007] Black wastewater is mainly water that comes from industrial discharges or fecal water that comes from sanitary fixtures of bathrooms of private dwellings, hotels, schools, hospitals, gyms and all places where sanitary fixtures are located.

[0008] Black wastewater also includes “blond water” that comes from bidets, showers, bathtubs and sinks of bathrooms, and grease condensation water. The latter arethose coming from the discharges of domestic kitchens and of restaurants, canteens, pizza restaurants and other premises where cooking is carried out, which contain not only fats and oils connected with the preparation of food, but also detergents and various soaps that are used for washing dishes.

[0009] Gray water is that coming from the discharges of laundries, kitchens and campsites and, therefore, produced with the use of for example caravans and motorhomes. The fundamental steps for a correct treatment of wastewater are usually identified in:

[0010] - screening: removal of the larger and superficial solid sediments (pieces of plastic, hygiene products and everything that accidentally ends up in the discharges)

[0011] - grit removal: separation of sand by natural sedimentation

[0012] - oil removal: elimination of oils and fats present in the water

[0013] - primary sedimentation: separation by gravity of the sedimentable solids, from this process sludge is removed

[0014] - activated sludge tank: through the action of microorganisms further removable material is formed

[0015] - final sedimentation: the water exiting from this last process can be defined as clean and ready to be returned to a surface watercourse.

[0016] However, such solution is not always possible and therefore, especially in the case of gray water, wastewater is collected in appropriate tanks.

[0017] Therefore, disposal stations are distributed over the territory, used mostly by camper users and campers, where it is possible to discharge the wastewater produced. However, such disposal stations are not particularly widespread and, often, are not easy to use and / or to locate.Another category of water is clear water in which white water falls (in which in turn mainly surface water falls such as that of rivers, springs, lakes, stagnant water, storage water), drainage water, phreatic water, well water, turbid water without fibres, sandy water, muddy water, water containing abrasive particles; rainwater, drainage water from roads, basements; groundwater, meteorological water (rainwater).

[0018] Clear water, in addition to having polluting elements (even if usually to a lesser extent than gray water and black water) is rich in bacteria both naturally and because, due to pollutants present in the ground, it is attacked by bacteria. Therefore, it is very rarely usable without a treatment that, at least for some aspects, recalls that described above and therefore is not further detailed.

[0019] The known art described also comprises further important drawbacks.

[0020] In fact, the storage of water, being particularly rich in bacteria, gives rise to a dangerous bacterial proliferation which, in addition to being dangerous for the environment and / or people, is a source of bad odours.

[0021] Therefore, by virtue of the above-mentioned drawbacks, often many users abusively discharge the water into drains or even into channels and streams, further deteriorating the quality of clear water.

[0022] Another drawback is therefore represented by the fact that the water, even if clear, is unusable also for simple operations of cleaning surfaces such as, for example, kitchen worktops or dishes.

[0023] In this situation, the technical task underlying the present invention is to devise a process for the treatment of water capable of substantially overcoming at least part of the drawbacks mentioned.

[0024] Within said technical task, an important purpose of the invention is to achieve aprocess that allows a simple and rapid treatment of water allowing a more rapid new use thereof.

[0025] In particular, one purpose is to have a process that allows a rapid and simple disposal of water especially if wastewater.

[0026] A not secondary task is to have a process that allows treating water, whether wastewater or clear water, without impacting on a subsequent use thereof. In particular, one purpose is to implement a process that allows immediate use of the treated water also to perform the cleaning and in detail the bacterial reduction of surfaces such as worktops and dishes.

[0027] Another important purpose of the invention is to implement a treatment process that is economical, practical and simple to implement and therefore to use.

[0028] The technical task and the specified purposes are achieved by a process for the treatment of water as claimed in the appended claim 1. Preferred embodiments are described in the dependent claims.

[0029] In the present document, the measurements, the values, the shapes and the geometric references (such as perpendicularity and parallelism), when associated with words such as “about” or other similar terms such as “approximately” or “substantially”, are to be understood as within measurement errors or inaccuracies due to production and / or manufacturing errors and, above all, within a slight deviation from the value, the measurement, the shape or geometric reference to which they are associated. For example, such terms, if associated with a value, preferably indicate a divergence not exceeding 10% of the value itself.

[0030] Moreover, when used, terms such as “first”, “second”, “upper”, “lower”, “main” and “secondary” do not necessarily identify an order, a priority of relationship or relative position, but can simply be used to more clearly distinguish different componentsfrom one another.

[0031] Unless otherwise indicated, “perpendicular”, “transverse”, “parallel” or “normal” or other terms of geometric positioning between geometric elements (for example axes, directions and lines) are to be understood with reference to their reciprocal geometric position between the corresponding projections. Said projections are defined on a single plane parallel to the plane(s) of arrangement of said geometric elements.

[0032] The measurements and data reported in the present text are to be considered, unless otherwise indicated, as carried out in International Standard Atmosphere ICAO (ISO 2533:1975).

[0033] The treatment process according to the invention comprises an introducing step into water of a treatment compound of the same water suitably black, gray and clear and preferably gray and clear.

[0034] In this document the term water identifies wastewater (that is water deriving from use in human, domestic, industrial or agricultural activities) such as black water and preferably gray water. In addition or as an alternative, the term water also identifies clear water which, as described above, is substantially constituted by white water, drainage water, phreatic water, well water, turbid water without fibres, sandy water, muddy water, water containing abrasive particles; drainage water from roads, basements; groundwater, meteorological water (rainwater).

[0035] Consequently, in the introducing step the treatment compound can be introduced into clear water (in detail white water), for example, to be used at the end of the treatment process for washing surfaces. Alternatively or in addition, in the introducing step the treatment compound can be introduced into gray water. In a further alternative or in addition, in the introducing step the treatment compound canbe introduced into wastewater.

[0036] Preferably, in the introducing step the treatment compound can be introduced into clear or gray water.

[0037] In the introducing step the water can be stored inside a tank made, for example, of metallic and / or plastic material.

[0038] The treatment compound and therefore the process are configured to perform a treatment preventing a bacterial proliferation of said water and more in particular reducing the bacterial load of said water.

[0039] Suitably, the compound and therefore the treatment process are configured to perform said treatment of wastewater, in detail black wastewater or gray water and preferably gray water. Alternatively or in addition, the compound and therefore the treatment process are configured to perform said treatment of clear water.

[0040] The treatment compound is identifiable in a totally inorganic mixture.

[0041] It can be in the form of powder or granules.

[0042] The treatment compound comprises at least one zinc salt and precisely more zinc salts.

[0043] Said at least one zinc salt is water-soluble and therefore able to dissolve and therefore dissociate releasing Zn2+ions when the compound is introduced into the water. In particular, said at least one zinc salt has a solubility constant Kpssubstantially at least equal to 1 x10-33Preferably the solubility constant Kpsis substantially comprised between 9*10-33and 1.5x10-11.

[0044] The solubility constant Kpsdefines the number of moles dissolved in a solvent (in this case in water) when said solvent is saturated.

[0045] Moreover, said at least one zinc salt is non-corrosive with respect to plastic and / or metallic materials so as to avoid damaging the possible storage volume of the water.Suitably, the compound comprises said at least one water-soluble zinc salt selected from one or more of zinc acetate, zinc lactate, zinc carbonate, zinc sulfate, zinc citrate, zinc PCA (zinc salt of pyrrolidone carboxylic acid). In particular, it comprises, suitably in an exclusive manner, zinc acetate, zinc lactate, zinc carbonate, zinc sulfate, zinc citrate and zinc PCA.

[0046] The content of zinc acetate is substantially comprised between 0.5 g / L and 20 g / L and preferably substantially equal to 5 g / L.

[0047] It is noted that, in this document, the content of each component is expressed as a function of the volume of water to be treated and, therefore, in which such compound is introduced. In particular, the content values expressed in this document are to be understood in grams for each liter of water.

[0048] The content of zinc lactate is substantially comprised between 0.5 g / L and 20 g / L and preferably substantially equal to 5 g / L.

[0049] The content of zinc carbonate is substantially comprised between 0.1 g / L and 10 g / L and preferably substantially equal to 2.5 g / L.

[0050] The content of zinc sulfate is substantially comprised between 0.5 g / L and 20 g / L and preferably substantially equal to 5 g / L.

[0051] The content of zinc citrate is substantially comprised between 0.1 g / L and 10 g / L and preferably substantially equal to 2.5 g / L.

[0052] The content of zinc PCA is substantially comprised between 0.5 g / L and 20 g / L and preferably substantially equal to 5 g / L.

[0053] For completeness, the content of each zinc salt with respect to the weight of the entire compound is reported.

[0054] The content of zinc acetate is substantially comprised between 30% and 70% and preferably 40-50% of the weight of the compound.The content of zinc lactate is substantially comprised between 5% and 30% and in detail between 10% and 20% of the weight of the compound.

[0055] The content of zinc carbonate is substantially lower than 15% and in detail substantially comprised between 1 % and 10% of the weight of the compound. The content of zinc sulfate is substantially comprised between 1% and 30% and precisely between 4% and 20% of the weight of the compound.

[0056] The content of zinc citrate is substantially lower than 15% and in detail substantially comprised between 1% and 10% of the weight of the compound.

[0057] The content of zinc PCA is substantially comprised between 1% and 30% and precisely between 4% and 20% of the weight of the compound.

[0058] The treatment compound comprises carbonate-hydroxyapatite preferably at least partially doped with Zn2+ions. Preferably, in the carbonate-hydroxyapatite the Ca2+ions are at least partially (in detail only partially) replaced with Zn2+ions. Precisely, the Zn2+ions are added to the carbonate-hydroxyapatite by substitution of Ca2+ions in the crystal structure of the apatite and / or by insertion in interstitial position in the crystal structure of the carbonate-hydroxyapatite. More precisely, the Zn2+ions are added both by said substitution and by said insertion.

[0059] It is noted that carbonate-hydroxyapatite, that is carbonated hydroxyapatite, is in fact characterised in that it is a variety of hydroxyapatite with some of the phosphate groups (PO4) replaced by carbonate groups (CO3). For example, in nature carbonate-hydroxyapatite can be of type A (Ca5(P04)2.5(C03)o.5(OH)) in which the carbonate ion with charge -2 replaces two OH groups with charge -1 ; and that of type B (Ca5(PO4,CO3)3(OH)) where one phosphate ion is replaced with one carbonate ion.Carbonate-hydroxyapatite therefore clearly differs from other substances and, in fact, was considered a species in itself as compared, for example, to hydroxyapatite. Such diversity is for example evidenced by the fact that the inorganic phase of dental enamel is predominantly hydroxyapatite, whereas the bone phase of dentine and dental pulp is exclusively constituted by carbonate-hydroxyapatite. Thus, the great difference of functional and mechanical properties between hydroxyapatite and carbonate-hydroxyapatite is evident. This difference appears even more evident with respect to the role with regard to the bacterial load of water, carbonate-hydroxyapatite, unlike hydroxyapatite, implements an actual scaffold for bacterial growth and in detail an extremely favourable scaffold for the particular types of bacteria present in water (especially in wastewater such as black water and even more gray water) which consequently are more easily neutralised by the Zn2+ions present on the surface of the nanocrystals of carbonate-hydroxyapatite making them bacteriostatic and not antibacterial as would have occurred if a Zn-substituted hydroxyapatite had been used. The use of carbonate-hydroxyapatite thus allows using in the application bacteriostatic powders that are not capable of killing bacteria, but only of preventing their reproduction and not antibacterial powders as would have been the case if Zn-substituted hydroxyapatite having antibacterial action had been used.

[0060] The carbonate-hydroxyapatite is in the form of micrometric granules.

[0061] The content of carbonate-hydroxyapatite is substantially comprised between 0.1 g / L and 10 g / L and preferably substantially equal to 2.5 g / L.

[0062] The content of carbonate-hydroxyapatite is substantially comprised between 0.5% and 30%, in detail between 1% and 15%, more in detail between 1% and 10%, even more in detail between 1 % and 5% of the weight of the compound.Subsequently to the introducing step, the treatment process comprises an abatement step in which the compound, remaining in said water, prevents the bacterial proliferation in said water and more in particular reduces the bacterial load thereof.

[0063] The abatement step can have a duration at least equal to one day and for example substantially comprised between three and seven days. For example, in the cases set out below said duration is five days.

[0064] In said abatement step the water can be substantially static, that is not agitated by suitable agitation means.

[0065] In this step the Zn2+ions, deriving from the dissociation of said at least one zinc salt, perform a first abatement of the bacterial proliferation and therefore of the bacterial load in the water.

[0066] Such action is assisted by the presence of the carbonate-hydroxyapatite suitably zinc-substituted which, being characterised by a negative electrical potential, attracts and therefore absorbs Zn2+ions, deriving from said at least one zinc salt, on its own surface.

[0067] Consequently, such synergistic action of said at least one zinc salt and of the carbonate-hydroxyapatite suitably zinc-substituted gives rise to a strong, but non-biocidal interaction with the microorganisms and bacteria present in the water, preventing their reproduction and therefore hindering an increase thereof and, over time, determining a drastic reduction of the bacterial load resulting from said nonreproduction.

[0068] It is noted that the form of nanostructured micrometric granules increases the surface area of the carbonate-hydroxyapatite and, therefore, favours the surface absorption of Zn2+ions by the same carbonate-hydroxyapatite.As proof of the above, the inventor has carried out a series of tests demonstrating the reduction of the bacterial load given by the adoption of the compound and therefore by the execution of the aforesaid process.

[0069] An experiment was carried out on gray wastewater. In this case two samples A and B of the same water and same volume (equal to 100 L) were obtained. Each of these samples was stored in a camper tank. The results were acquired in accordance with the standard APAT CNR IRSA 7040 C Man 292003.

[0070] In the tank of sample A no product was introduced. After 5 days sample A was analysed. Below is a summary table of the results of sample A

[0071]

[0072] Table 1 - Results of sample A

[0073] At this point sample B was carried out which was subjected to the treatment process. In detail, in the introducing step by introducing into said tank of sample B and, therefore, into said water the treatment compound and therefore performing the abatement step for five days. After 5 days sample B was analysed. Below is a summary table of the results of sample B

[0074]

[0075] Table 2 - Results of sample B

[0076] A second experiment was carried out on clear water. In this case samples C and D of the same water and same volume (equal to 100 L) were obtained.In the tank of sample C no product was introduced. After 5 days sample C was analysed. Below is a summary table of the results of sample C

[0077]

[0078] Table 3 - Results of sample C

[0079] At this point sample D, which was subjected to the treatment process, was carried out. In detail, in the introducing step by introducing into said tank of sample D and, therefore, into said water the treatment compound and therefore performing the abatement step for five days. After 5 days sample D was analysed. Below is a summary table of the results of sample D

[0080]

[0081] Table 4 - Results of sample D

[0082] It is noted that in this second experiment the presence of vital organisms at 22°C and at 36°C was evaluated in accordance with UNI EN ISO 6222:2001, whereas the presence of salmonella in accordance with ISTISAN 07 / 5 ISS A 011 B Rev. 00. A third experiment was carried out on black wastewater. In this case two samples E and F of the same black water and same volume (equal to 20 L) were obtained. Each of these samples was stored in a camper tank. The results were acquired in accordance with the standard APAT CNR IRSA 7040 C Man 292003.

[0083] In the tank of sample E no product was introduced. After 5 days sample E was analysed. Below is a summary table of the results of sample E.

[0084]

[0085] Table 5 - Results of sample E

[0086] At this point sample F, which was subjected to the treatment process, was carried out. In detail, in the introducing step by introducing into said tank of sample F and, therefore, into said water the treatment compound and therefore performing the abatement step for five days. After 5 days sample F was analysed. Below is a summary table of the results of sample F

[0087]

[0088] Table 6 - Results of sample F

[0089] The treatment process according to the invention and therefore the treatment compound achieve important advantages.

[0090] In fact, as emerged from the results set out above, the compound and therefore the treatment process allow reducing in an extremely significant manner the content of bacteria in water.

[0091] Another advantage lies in the fact that the compound and therefore the treatment process allow a simple and rapid treatment and therefore disposal of the water. A further advantage lies in the fact that the compound and the process are economical, practical and simple to use / implement.

[0092] It is noted that the process introduced by the present document does not fall within the numerous processes proposed for purifying surface water and wastewater in order to allow its use, but represents an innovative ecological and healthful methodfor the treatment and suitably the storage of water (preferably white, gray and black) reducing the bacterial load thereof without resorting to the use of biocides, toxic and polluting substances.

[0093] In fact, the process provides for a treatment of water comprising the introduction into the water of a compound comprising one or more zinc salts mixed with biomimetic nanoparticles of carbonate-hydroxyapatite doped with Zn2+ions. This inorganic compound does not contain biocides, quaternary bases and not only is not toxic, but is even edible. An important innovation of the present water treatment process lies precisely in the possibility of reducing the bacterial load without killing the bacteria, but simply counteracting their reproduction. In fact, the compound in water makes the environment with which it comes into contact “bacteriostatic”, that is it does not kill bacteria, but prevents their reproduction.

[0094] Such advantages result in numerous applications of the compound and therefore of the process in the agronomic, zootechnical and civil field thanks to the possibility of obtaining environments with a low degree of bacterial and viral contamination in civil activities, animal breeding and agricultural crops limiting the use of antibiotics and toxic biocides.

[0095] The invention is susceptible of variants falling within the scope of the inventive concept defined by the claims. Within this scope all details are replaceable by equivalent elements and the materials, the shapes and the dimensions may be any.

Claims

CLAI MS1. Water treatment process characterized in that it comprises an introducing step a treatment compound into said water; said compound comprising:- at least one zinc salt; and- carbonate-hydroxyl apatite at least partially doped with Zn2+ions.

2. Water treatment process according to claim 1 , wherein said water is selected between gray water, black water and clear water.

3. Treatment process according to at least one previous claim, wherein said treatment compound comprises zinc acetate, zinc lactate, zinc carbonate, zinc sulfate and zinc citrate PCA; and wherein, in the said introducing step, for each liter of said water said compound is introduced comprising between 0.5 g and 20 g of the said zinc acetate, between 0.5 g and 20 g of the said zinc lactate, between 0.1 g and 10 g of the said zinc carbonate, between 0.5 g and 20 g of said zinc sulfate, between 0.1 g and 10 g of said zinc citrate, between 0.5 g and 20 g of said zinc PCA, and between 0.1 g and 10 g of said carbonate-hydroxyapatite.

4. A treatment process according to claim 1 , wherein said treatment compound comprises zinc acetate, zinc lactate, zinc carbonate, zinc sulfate, and zinc citrate PCA; and wherein in said introduction step for each liter of said water 5 g of said zinc acetate, 5 g of said zinc lactate, 2.5 g of said zinc carbonate, 5 g of said zinc sulfate, 2.5 g of said zinc citrate, 5 g of said zinc PCA, and 2.5 g of said carbonate-hydroxyapatite are introduced.

5. Water treatment compound characterized in that it comprises- at least one zinc salt; and- a carbonate-hydroxyapatite at least partially doped with Zn2+ions.

6. A treatment compound according to claim 5, wherein said carbonate-hydroxyapatite is only partially doped with Zn2+ions.

7. A treatment compound according to at least one previous claim 5-6, wherein said carbonate-hydroxyapatite is in the form of micrometric granules.

8. A treatment compound according to at least one previous claim 5-7, wherein the content of said carbonate-hydroxyapatite is between 1 % and 5% of the weight of said compound9. Treatment compound according to at least one previous claim 5-8, wherein said at least one zinc salt includes said zinc acetate, said zinc lactate, said zinc carbonate, said zinc sulfate and said zinc citrate PCA.

10. A treatment compound according to claim 9, wherein the content of said zinc acetate is substantially between 30% and 70% of the weight of the compound; wherein the content of said zinc lactate is between 10% and 20% of said weight of the compound; wherein the content of said zinc carbonate is substantially between 1 % and 10% of said weight of the compound; wherein the content of said zinc sulfate is substantially between 4% and 20% of said weight of the compound; wherein the content of said zinc citrate is substantially between 1% and 10% of said weight of the compound; and wherein the content of said zinc PCA is substantially between 4% and 20% of said weight of the compound.

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