Device for producing calcium, alkalinity and micronutrients for marine aquariums

Abstract

The invention relates to a device of special practical use in marine aquariums and aquaculture, since it allows calcium, alkalinity and micronutrients to be produced for the maintenance of aquarium conditions, in order to maintain the levels necessary for the development of aquatic organisms. For this purpose, the device has a new feature based on an electrochemical reactor provided with a reaction chamber comprising a solid mineral substrate, at least one cathode and anode that are physically separated, a power source, and conduits between the aquarium and the electrodes, such that the device of the invention allows a stream of salt water to be acidified and the solid substrate or calcareous mineral bed to be dissolved, dosing water rich in calcium, alkalinity and micronutrients to the aquarium, all this being performed in a simple and controllable manner without needing CO2 gas streams.

Description

[0001] DESCRIPTION

[0002] Calcium, alkalinity and micronutrient production device for marine aquariums

[0003] FIELD OF INVENTION

[0004] The present invention falls within the field of marine aquarium water conditioning, specifically, in the treatment of aquarium water to supply alkalinity, calcium and other dissolved micronutrients essential for maintaining the aquarium conditions, through direct current electrolysis control of salt water.

[0005] More specifically, the device of the present invention allows acidifying a salt water stream and producing the dissolution of a solid substrate or calcareous mineral bed (commonly known by the English expression Reactor Media) and its dosage to an aquarium, in order to maintain the adequate levels of alkalinity, calcium and other micronutrients, necessary for the development of aquatic organisms, mainly coral skeletons.

[0006] This invention finds application in any type of recirculating aquaculture system, and more specifically in the field of ornamental aquaculture and aquariophilia.

[0007] BACKGROUND

[0008] Calcium reactors are commercial devices capable of generating essential nutrients (Ca 2+ , Mg 2+ , bicarbonates, trace elements, etc.) necessary for the growth of reef-forming hard corals.

[0009] These reactors can be automated and are widely used in both marine and reef aquariums because they promote the growth of these corals and provide alkalinity to the water. A wide variety of designs for this type of reactor are commercially available. Examples include commercial equipment such as those listed in the following links to companies that distribute aquaculture products: htDs: / / www.icasa.com / producto / reactor-de-caicio-aaua-ocean / :

[0010] A conventional calcium reactor is a vessel filled with solid calcium carbonate or solid substrates containing calcium carbonate, magnesium, and other trace elements. Aquarium water, to which carbon dioxide is added, is circulated through this vessel. This type of equipment is disclosed in patent or utility model documents such as CN217140418U 'Calcium reactor', CN208972351 U 'High-efficiency calcium reactor with strong ornamental value', US1 1369094B1 'Automatic calcium reactor', CN2930276Y 'Calcium reactor', or CN204120013U 'Novel calcium ion reactor'.

[0011] In known reactors, the addition of carbon dioxide reduces the pH of the water, making it acidic and dissolving the calcium carbonate and other elements that make up the solid substrate. In this way, the flow of water enriched with these elements is returned to the aquarium. The gaseous CO2 stream comes from a cylinder of this pre-sparked gas, which is bubbled into a chamber containing the mineral. The greatest complexity of this type of reactor lies in the handling of this carbon dioxide flow. In addition to the pre-sparked CO2 cylinder, a pressure reducer is required, while solenoid valves are used to introduce the CO2 into the reactor vessel.

[0012] To control the substrate dissolution process, it is necessary to use a pH probe inside the reactor or, alternatively, a method for measuring dissolved CO2. The pH probe is coupled to an automated CO2 flow controller to maintain the pH in the reactor within the range of 7.5–6.5. If the pH falls below this level, the controller cuts off the CO2 flow using a solenoid valve. When the pH value rises, the solenoid valve opens again. A needle valve and a drop counter are also required for fine adjustments to the CO2 bubbling rate.

[0013] The operating scheme of most commercial calcium reactors is disclosed, for example, on these web pages: https: / / www.buikreefsupply.com / content / post / md--2021-02--what--is--a--calcium- reactor https: / / en.wikipedia.org / wiki / Calcium reactor

[0014] The sheer complexity of commercial calcium reactors means they are rarely used in aquariophilicity, particularly in small and medium-sized domestic or ornamental aquariums. This is primarily due to the need to use CO2 gas, which is usually stored in cylinder form. The need for fine-tuning the flow of this gas requires the use of complicated mechanisms, gas lines, and control devices (pressure regulator, drop counter, solenoid valves, pH meter coupled to a current regulator to control the solenoid valve), as detailed above.

[0015] The extreme difficulty of this control sometimes means that nutrient dosages are not precisely regulated. This requires the intervention of qualified personnel trained in the use of the devices to prevent incidents due to excess acidification or other nutrients, which negatively affect the live species in the aquarium and can lead to their death.

[0016] In marine aquarium maintenance applications, various devices based on electrochemical technologies are known for the maintenance and control of aquarium water, such as the one disclosed in document CN203860248U, which refers to an electrochemical reactor consisting of an anode and a cathode separated by an insulating mesh, and whose purpose is the elimination of substances harmful to the aquarium, such as harmful algae or bacteria.

[0017] Document CN105660485B discloses a method and device for artificial coral growth, based on the electrolysis of seawater to dissolve a substrate containing calcium and deposit calcium carbonate crystals on an iron frame in the cathode chamber, creating a growth base for the coral. However, this disclosure does not contemplate a device that provides calcium or carbonic alkalinity to the water in an aquarium, since the calcium carbonate is retained in the reactor itself at the cathode. On the other hand, other devices for generating mineral water for human consumption are known, such as those disclosed in documents JP2003062574A and JPH09253663A, which disclose an electrolytic bath in which water is acidified at the anode, thus promoting the dissolution of a CaCO3-rich substrate.In these inventions, the acidified water flow from the anode is mixed with the alkaline flow from the cathode to obtain a water stream with a neutral pH, suitable for human consumption but not for use in aquariums. This is because the basic pH flow would partially remove the nutrients supplied in the anolyte by the acidification of the water, primarily in the form of insoluble carbonates. Therefore, the water obtained would not provide the carbonic alkalinity required for an aquarium.

[0018] DESCRIPTION OF THE INVENTION

[0019] The invention described below satisfactorily resolves the detailed problem, since it allows the provision of alkalinity, calcium and other micronutrients by contact with a calcareous mineral bed of an aquarium water stream acidified by electrolytic means, which has important advantages over conventional systems that use gaseous CO2 streams.

[0020] Advantageously, the acid equivalents required for dissolving the appropriate doses of calcium and alkalinity can be automatically regulated very precisely, using an electronic control system of the applied current / voltages, without the need for more expensive and complex gas storage and supply systems.

[0021] To this end, the proposed device comprises the following elements:

[0022] - an electrochemical reactor provided with a reaction chamber (containing a solid mineral substrate with at least calcium carbonate), at least one anode and at least one cathode, which are arranged physically separated, avoiding electrical contact,

[0023] - at least one power supply, preferably a low power DC power supply, such that the anode electrode is connected to the positive terminal of said power supply by means of a first cable, and the cathode electrode is connected to its negative terminal by means of a second cable, - at least one first conduit conducting water from the aquarium to the anode,

[0024] - at least a second line that carries water from the reaction chamber to the aquarium,

[0025] Thus, the power supply applies a current that causes the aquarium water to oxidize at the anode, producing protons that electrolytically acidify the water. To this end, the power supply may have manual regulation, programmable regulation, and / or remote control. The current applied by the power supply is a measure of the rate at which the electrochemical reaction of water oxidation occurs. This parameter can be regulated by the power supply. Thus, the current density applied to the anode electrode is preferably between 0 and 0.200 A / cm. 2, where the current density refers to the quotient between the current applied by the power supply and the geometric area of ​​the electrode, and is directly proportional to the concentration of the species that are transformed on that electrode, that is, the higher the current density, the higher the speed of the electrolysis reaction.

[0026] Well, the water thus acidified dissolves the solid mineral substrate (Reactor Media) contained in the reaction chamber and at least Ca ions are released into the water. 2+ and bicarbonate ions, so that water with Ca ions 2+ and bicarbonate ions are returned to the aquarium through the second conduit. Solid mineral substrate can be found in a variety of formats, such as stones, granules of various sizes, tablets, powder, or compacted powder, with powder being preferred as it facilitates the dissolution process.

[0027] In addition to calcium carbonate, the solid mineral substrate may contain other nutrients such as nitrates, phosphates, magnesium, strontium, potassium, manganese, nickel, zinc, vanadium, molybdenum, bromide, iodide and / or fluoride.

[0028] The anode may be formed by any chemically stable electrode under operating conditions, such as mixed metal oxide (MMO) electrodes, also known as DSA (Dimensionally Stable Anode) electrodes, stable carbonaceous electrodes such as vitrified carbon, or boron-doped diamond electrodes. In terms of configuration, the anode may be a flat electrode, a circular electrode, a grid electrode, a spun electrode, an expanded metal electrode, a metal foam electrode, or any other configuration that provides an equivalent result.

[0029] Regarding the cathode, it is made up of any conductive material that does not modify the composition of the aquarium water during the electrochemical reaction, preferably a carbonaceous material (graphite, vitrified carbon, boron-doped diamond, etc.), or a metallic material (titanium, steel, copper or nickel, or their alloys, for example).

[0030] On the other hand, the location of the electrodes in the device may vary according to different embodiments of the invention. Thus, the anode may be arranged inside the reaction chamber, such that, for example, the solid mineral substrate (Reactor Media) is in physical contact with the anode. In this embodiment, it is necessary for the flow of water through the reaction chamber to be slow to ensure the contact time necessary for the reaction between the acid produced in the anode and the solid mineral substrate.

[0031] Alternatively, the anode is arranged in a tank separate from the reaction chamber, such that the water to be acidified by electrolysis first passes through the separate tank containing the anode, so that the water is acidified and subsequently conducted to the reaction chamber, where the mineral substrate is dissolved.

[0032] The cathode(s) may also be placed inside the reaction chamber, without contact with the anode, in the aquarium itself or in a filtration sump.

[0033] Preferably, in all the embodiments described above in which there is no membrane separation between the electrodes - that is, whether the cathode is in the same reaction chamber, in the aquarium or in the sump - the surface area of ​​the cathode is at least 10 times greater than the surface area of ​​the anode, such that the current density at the cathode is at least 10 times lower than the current density at the anode. This causes the proton consumption that occurs at the cathode to be much lower than the proton production at the anode, thus avoiding basification in the vicinity of the cathode. In this sense, excessive basification in the cathode would produce a calcium carbonate deposition process (which is the reverse reaction to that which occurs in the anode), as occurs in the device disclosed in document CN105660485B cited in the 'Background' section of this report.The device has an anode compartment containing the anode and a cathode compartment containing the cathode, both compartments separated by an ion exchange membrane. Advantageously, since the cathode compartment is isolated from the aquarium by a membrane, the reactions occurring at the cathode do not influence the chemical composition of the aquarium water.

[0034] Thus, the device of the invention allows for a controlled supply of carbonic alkalinity and other micronutrients, which does not alter the chemical composition of the aquarium water, since the configurations described above prevent unwanted secondary reactions of water reduction at the cathode, which would affect the composition and pH of the aquarium water. In the embodiments in which the cathode is arranged inside the reaction chamber, in the aquarium itself or in a filtration sump thereof, unwanted reactions at the cathode that would lead to alkalinity in its environment are prevented by decreasing the current density therein through an appropriate relationship between the surface areas of the anode and cathode; while in the embodiment in which the anode and cathode are located in compartments separated by a membrane, unwanted reactions at the cathode are prevented by the reaction occurring therein outside the aquarium.

[0035] Optionally, the device may include one or more pumps for transferring water between the aquarium and the electrochemical reactor. Also optionally, the device has at least one plastic grid inside the reaction chamber to retain the solid mineral substrate.

[0036] The invention also relates to the process for producing calcium, alkalinity and micronutrients using the device described, a process which, as detailed above, is based on the electrolytic acidification of a water stream, which is produced by anodic oxidation of water by applying electric current, and which comprises the steps of:

[0037] - Conveying a flow of water from the aquarium or the filtration sump to the electrochemical reactor through a first conduit by means of the necessary conduction means, such as, for example, gravity fall through conduits, or more preferably by using a drive pump. The electrochemical reactor is provided with an anode and a cathode that are arranged without physical contact, as well as a reaction chamber containing the solid mineral substrate (Reactor Media) with, at least, calcium carbonate. - Circulating the water through the reaction chamber, with a preferred flow rate between 0 L / h and 1 L / h for each liter of total aquarium volume, while the power supply applies an electric current, preferably with a current density at the anode of between 0 and 0.200 A / cm 2 .

[0038] Electrolysis of the water flow that passes through the reaction chamber, such that water oxidation reactions occur at the anode, generating oxygen and protons that acidify the electrode environment:

[0039] 2 H2O(I) O2(g) + 4H + (aq) +4e'

[0040] - Dissolution of the solid substrate by the acidified water in the reaction chamber. The resulting reaction releases bicarbonate ions, calcium, and other calcareous minerals contained in the substrate. The main reaction is:

[0041] CaCO3(s) + H + (aq) — > HCO3“(aq) + Ca 2+ (aq)

[0042] Thus, the oxidation process taking place at the anode causes the water to acidify. The acidified water dissolves the solid substrate, enriching it with carbonate and bicarbonate ions. This water, with its higher carbon alkalinity, is then added to the aquarium. The rate at which the solid substrate particles in the reaction chamber dissolve depends on the current applied by the power supply, so the salt supply can be precisely regulated by electronic control. The electrodes are polarized by the adjustable direct current source, connecting the positive pole to the anode electrode and the negative pole to the cathode electrodes. Electrolysis can be performed galvanostatically or at constant cell voltage. Galvanostatic electrolysis is preferably used, as it allows for better control of the process and a controlled rate of calcium supply.

[0043] - Return of water enriched with Ca(II) ions and bicarbonate ions, among other micronutrients, to the aquarium through a second line. This return to the main body of water in the aquarium or the sump can be achieved using a booster pump or by gravity. Ultimately, the device and method of the invention have the following advantages over conventional reactors:

[0044] - The use of CO2 gas is eliminated, eliminating the need for gas flow regulation and the components and mechanisms required for it. This results in a simplified design and reduced costs.

[0045] - It allows for the automatic and precise dosing of calcareous minerals by regulating the applied current and, therefore, the simple control of the system using an electronic device.

[0046] BRIEF DESCRIPTION OF THE FIGURES

[0047] To complement the description that follows and in order to help better understand the characteristics of the invention, in accordance with some preferred examples of practical implementation thereof, some figures are attached as an integral part of said description, in which the following has been represented for illustrative and non-limiting purposes:

[0048] Figure 1 shows a diagram of the device according to a first embodiment of the invention.

[0049] Figure 2.- Shows a diagram of a second embodiment of the device of the invention, in which the anode is arranged inside the reaction chamber, which has a tubular geometry, and in which the cathode is configured as a grid that is arranged in the aquarium.

[0050] Figure 3.- Shows a diagram of a third embodiment of the invention in which the device has an anode compartment and a cathode compartment separated by an ion exchange membrane, and which is additionally provided with an auxiliary tank that forms a hydraulic circuit with the cathode compartment.

[0051] DETAILED EXPLANATION OF IMPLEMENTATION METHODS

[0052] In view of the figures shown, it can be seen that the device of the invention is based on the structure comprising the following elements: - an electrochemical reactor provided with a reaction chamber (3), at least one anode (4) and at least one cathode (5), which are arranged physically separated, avoiding electrical contact,

[0053] - at least one power supply (7) connected by a first cable (4') to the anode (4) and by a second cable (5') to the cathode (5),

[0054] - at least a first conduit (8) that conducts water from the aquarium (1) to the anode (4), and

[0055] - at least a second conduit (9) that conducts water from the reaction chamber (3) to the aquarium (1), where the reaction chamber (3) is provided with a solid mineral substrate (6) that will generate the nutrients during its dissolution, and that contains, at least, calcium carbonate.

[0056] Thus, a flow of water (8') is circulated from the aquarium or the aquarium sump through the first conduit (8) towards the electrochemical reactor, preferably using a drive pump (2), as in the embodiment illustrated in Figure 3.

[0057] According to what is illustrated in figure 2, the anode (4) is arranged in the reaction chamber (3), which has a tubular geometry, however, other designs can be selected for the reaction chamber (3) based on the different types of aquarium filters: backpack filters, canister type, internal filters, bioreactors, etc.

[0058] The anode electrode (4) is connected by means of the cable (4') to the positive terminal of a direct current power supply (7). After the water has passed through the reactor, the return water outflow (9') is conducted back to the aquarium (1 ) or to the sump through the second conduit (9). In the embodiments illustrated in Figures 1 and 2, the cathode (5) is located in the aquarium (1 ) or sump, the cathode (5) being connected to the power supply (7) by means of the corresponding cable (5').

[0059] On the other hand, an alternative embodiment is illustrated in Figure 3 in which the anode (4) is arranged in an anode compartment (10), while the cathode (5) is arranged in a cathode compartment (10'), both compartments being separated by an ion exchange membrane (11). Additionally, the device has an auxiliary tank (3'), such that a third conduit (12) conducts the water from the anode compartment (10) to the reaction chamber (3), a fourth conduit (13) conducts the water from the auxiliary tank (3') to the cathode compartment (10') and a fifth conduit (14) conducts the water from the cathode compartment back to the auxiliary tank (3'). The hydraulic circuit formed by the auxiliary tank (3') and the cathode compartment (10') is provided with a valve or gas outlet for the evacuation of the gases generated in the cathode (5).The auxiliary tank (3') contains aquarium water or any water solution with dissolved salts.

[0060] As detailed in figure 3, the device is provided with a drive pump (2) for transferring water between the aquarium (1) and the electrochemical reactor, as well as a second drive pump (2') for circulating the water through the hydraulic circuit consisting of the cathode compartment (10'), the fourth conduit (13), the auxiliary tank (3') and the fifth conduit (14).

Claims

CLAIMS 1 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums characterized by comprising: - an electrochemical reactor provided with a reaction chamber (3), at least one anode (4) and at least one cathode (5), which are arranged physically separated, avoiding short circuits, and a reaction chamber (3) provided with a solid mineral substrate (6) containing at least calcium carbonate, - at least one power supply (7) connected by a first cable (4') to the anode (4) and by a second cable (5') to the cathode (5), - at least a first conduit (8) that conducts water from the aquarium (1) to the anode (4), - at least a second conduit (9) that conducts water from the reaction chamber (3) to the aquarium (1), where by applying the power supply (7) an electric current causes the oxidation of the aquarium water at the anode (4), producing protons that electrolytically acidify the water, such that the acidified water dissolves the solid substrate (6) contained in the reaction chamber (3) and releases at least Ca ions into the water. 2+ and bicarbonate ions, so that water with Ca ions 2+and bicarbonate ions are returned to the aquarium (1 ) through the second conduit (9); where the device has an anode compartment (10) where the anode (4) is arranged, a cathode compartment (10') where the cathode (5) is arranged, an ion exchange membrane (1 1) that separates both compartments [(10), (10')] and an auxiliary tank (3'), such that a third conduit (12) conducts the water from the anode compartment (10) to the reaction chamber (3), a fourth conduit (13) conducts the water from the auxiliary tank (3') to the cathode compartment (10') and a fifth conduit (14) conducts the water from the cathode compartment back to the auxiliary tank (3'), the hydraulic circuit formed by the auxiliary tank (3') and the cathode compartment (10') being provided with a valve or gas outlet for the evacuation of the gases generated in the cathode (5). 2 a.- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the power supply (7) applies a current density to the anode of between 0 and 0.200 A / cm 2 . 3 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the power supply (7) has manual regulation means, programmable regulation means and / or remote control means. 4 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the anode (4) is arranged inside the reaction chamber (3). 5 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a, characterized in that the anode (4) is arranged in a tank independent of the reaction chamber (3), so that the water first passes through the independent tank for acidification and secondly the acidified water is taken to the reaction chamber (3). 6 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the hydraulic circuit formed by the auxiliary tank (3') and the cathode compartment (10') are provided with a valve or gas outlet for the evacuation of the gases generated in the cathode (5). 7 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a, characterized in that it is provided with a drive pump (2) for the circulation of water through the first conduit (8) and the second conduit (9) for the transfer of water between the aquarium (1) and the electrochemical reactor. 8 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that it is provided with a drive pump (2') for the circulation of water through the hydraulic circuit consisting of the cathode compartment (10'), the fourth conduit (13), the auxiliary tank (3') and the fifth conduit (14). 9 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1, characterized in that the anode (4) is made up of a mixed metal oxide (MMO) electrode, a stable carbonaceous material electrode or a boron-doped diamond electrode. 10a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1, characterized in that the anode (4) is a flat electrode, a circular electrode, a grid electrode, a spun electrode, an expanded metal electrode or a metal foam electrode. 1 1 Calcium, alkalinity and micronutrient production device for marine aquariums, according to claim 1 a , characterized in that the cathode (5) is made up of a carbonaceous material or a metallic material. 12 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the reaction chamber (3) has a tubular geometry. 13 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a, characterized in that the solid mineral substrate (6) is in the form of stones, granules, powder, compacted powder or tablets. 14 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that the solid mineral substrate (6) contains nitrates, phosphates, magnesium, strontium, potassium, manganese, nickel, zinc, vanadium, molybdenum, bromide, iodide and / or fluoride. 15 a .- Device for producing calcium, alkalinity and micronutrients for marine aquariums, according to claim 1 a , characterized in that it has at least one plastic material grid inside the reaction chamber (3) for retaining the solid substrate (6).

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