Electrochemical wastewater treatment systems and methods of using the same

Abstract

Provided herein is an electrochemical wastewater treatment system that includes: an electrochemical cell including at least two liquid compartments, including an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in wastewater upon application of an electric field, and wherein the system is configured to transfer at least a portion of a catholyte solution produced at the catholyte compartment upon application of the electric field, towards the anolyte compartment, to increase the pH of the produced anolyte solution.

Description

[0001] ELECTROCHEMICAL WASTEWATER TREATMENT SYSTEMS AND METHODS OF USING THE SAMETECHNICAL FIELD

[0002] The present disclosure relates to the field of water purification. More specifically, the disclosure relates to a pH-regulated electrochemical system used for wastewater treatment.

[0003] BACKGROUND

[0004] Efficient wastewater treatment technologies are important for public health and environmental protection, water conservation, reduction of pollution, and economics. Electrochemistry is one of the more energy-efficient technologies, especially when it concurrently produces a viable product, such as hydrogen. During electrochemical wastewater treatment, contaminants like ammonia can be oxidized at the anodic side of the electrochemical cell and transformed into a non-harming product.

[0005] During electrochemical treatment, pH changes occur in the anolyte and catholyte compartments. At the anode of the anolyte compartment, oxidative reactions, such as Oxygen Evolution Reaction (OER) and / or oxidation of Ammonia, release protons, leading to an acidic environment and a decrease in pH level. Conversely, at the cathode of the catholyte compartment, Hydrogen Evolution Reaction (HER) promotes the production of hydroxide ions and increases the pH, resulting in a more basic catholyte solution.

[0006] The acidic environment, such as is developed at the anolyte, can accelerate corrosion of the anode, especially if it is made of metals or metal oxides vulnerable to acid. Acidity can also slow reaction kinetics at the anode and promote the production of hazardous gases such as Chlorine that affect the system's safety operation.

[0007] Various solutions have been proposed to overcome the acidic environment. These include the use of acid-resistant membranes, cells, and electrodes. However, such optimizations may compromise the material and structure intended for high-performing treatment systems. More operational solutions for the challenge may include lowering the temperature, use of a buffer, a dilution of the anolyte, or a titration of the anolyte solution by an externally added alkaline solution. However, such operational solutions may complicate the performance and operation of the electrochemical device or require the use of consumables (e.g., alkaline salts).Therefore, there is a need in the art for an efficient and precise system to resolve the increase of acidity in the anolyte compartment during electrochemical wastewater treatment.

[0008] SUMMARY

[0009] This disclosure is directed, in embodiments thereof, to a pH-regulated electrochemical system for use in wastewater treatment. According to some embodiments, the wastewater treatment system produces treated wastewater having a reduced amount of ammonia. Furthermore, according to some embodiments, the system may produce hydrogen gas.

[0010] According to some embodiments, provided herein is a system and a method that facilitates the transfer of at least a portion of the alkaline catholyte solution produced at the catholyte compartment towards the anolyte compartment of the system, thereby advantageously increasing the pH level at the anolyte compartment.

[0011] According to some embodiments, the system includes a conduit assembly that fluidly connects the catholyte compartment outlet to the anolyte compartment, around a separating membrane of the electrochemical cell. In this configuration, the system allows the transfer of the produced catholyte solution from the catholyte compartment to the anolyte compartment, while bypassing the membrane, to increase the pH level in the anolyte compartment. One or more pumps, one or more sensors, and / or reservoir tank(s) may facilitate the transfer and regulation of the pH.

[0012] Alternatively, or in addition, according to some embodiments, the system includes a catholyte outlet that selectively permits output of gas and limits output of liquid. In this configuration, the catholyte solution produced in the catholyte compartment is forced to pass through the membrane (e.g., porous diaphragm) towards the anolyte compartment, thereby increasing the pH level at the anolyte compartment.

[0013] According to some embodiments, the transfer of at least a portion of the produced catholyte solution is performed continuously and / or intermittently. In some embodiments, the rate of the transfer of the produced catholyte solution may be determined and regulated according to the pH level sensed at the catholyte compartment, the anolyte compartment, and / or at the wastewater source.There is provided, in accordance with some aspects of the presently disclosed subject matter, an electrochemical wastewater system including:

[0014] an electrochemical cell including at least two liquid compartments, including an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in the wastewater upon application of an electric field;

[0015] a wastewater tank connected via a first conduit assembly to one or more inlets of the electrochemical cell;

[0016] an anolyte outlet, configured to output treated wastewater; and

[0017] one or more catholyte outlets, including:

[0018] a first catholyte outlet including a first valve configured to selectively permit a gas output from the catholyte compartment, thereby facilitating a liquid pressure in the catholyte compartment that directs passage of at least a portion of a catholyte solution produced upon the application of the electric field, through the membrane to the anolyte compartment; and / or

[0019] a second catholyte outlet configured to enable output of a catholyte solution produced upon the application of the electric field, the second outlet being connected to a second conduit assembly bypassing the membrane, wherein the second conduit assembly is further connected to the one or more inlets of the electrochemical cell and / or the wastewater tank to enable transfer at least a portion of the produced catholyte solution towards the anolyte compartment and / or the wastewater tank.

[0020] According to some embodiments, the pH level in the anolyte compartment is configured to be maintained at a value of at least about pH 4.

[0021] According to some embodiments, the pH value at the anolyte compartment is configured to be maintained at a value in the range of about pH 4-12.

[0022] According to some embodiments, the amount of an external alkaline agent required to neutralize the total anolyte solution is below 2 molOH / molN.According to some embodiments, the membrane is microporous, thereby enabling the passage therethrough of the produced catholyte solution liquid towards the anolyte compartment.

[0023] According to some embodiments, the membrane is a porous diaphragm.

[0024] According to some embodiments, the porous diaphragm includes poly(vinylidene fluoride) (PVDF), Polytetrafluoroethylene (PTFE), polypropylene (PP), and / or polyethylene (PE).

[0025] According to some embodiments, the second conduit assembly includes a bypass pump to enable the transfer of at least a portion of the produced catholyte solution to the anolyte compartment and / or the wastewater tank.

[0026] According to some embodiments, the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution when the pH thereof is above a pH threshold in the range of about pH 12-14.

[0027] According to some embodiments, the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution when the pH at the anolyte compartment is below a pH threshold of about pH 4.

[0028] According to some embodiments, the system further includes a catholyte tank fluidly connected to one or more of: the catholyte compartment, a make-up fluid source, the anolyte compartment, and / or a wastewater tank.

[0029] According to some embodiments, the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution directly from the catholyte compartment to the anolyte compartment.

[0030] According to some embodiments, the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution to the wastewater tank.

[0031] According to some embodiments, the system further includes a make-up fluid source connected to a catholyte tank or to the catholyte compartment; the make-up fluid includes water, treated water, salt, wastewater, or any combination thereof.

[0032] According to some embodiments, the make-up fluid source includes wastewater.According to some embodiments, the membrane is a cation exchange membrane (CEM).

[0033] According to some embodiments, the CEM includes a perfluorinated backbone.

[0034] According to some embodiments, the system further includes one or more pH sensors configured to measure pH levels.

[0035] According to some embodiments, at least one of the one or more pH sensors is functionally associated with the second conduit assembly, the first valve, and / or the second valve, and is configured to directly or indirectly regulate the transfer of at least a portion of the produced catholyte solution, based on the measured pH level.

[0036] According to some embodiments, the one or more pH sensors is positioned in, and / or is configured to, measure pH level at one or more of the following: the catholyte compartment, the anolyte compartment, the wastewater tank, and / or any inlet or outlet thereof.

[0037] According to some embodiments, the system is for use in reducing ammonia concentration in aqueous solution. According to some embodiments, the aqueous solution is wastewater

[0038] According to some embodiments, the system is for use in producing hydrogen gas.

[0039] There is provided, in accordance with some aspects of the presently disclosed subject matter, a method for treating wastewater, the method includes:

[0040] allowing wastewater to reach the electrochemical cell of the herein disclosed electrochemical wastewater system;

[0041] applying an electric field between the catholyte and anolyte compartments, to oxidize one or more contaminants in the anolyte compartment and produce a catholyte solution in the catholyte compartment; and

[0042] transferring at least a portion of the produced catholyte solution towards the anolyte compartment.

[0043] According to some embodiments, the pH level at the anolyte compartment is maintained at a value of at least about 4.According to some embodiments, the transfer of the produced catholyte solution is performed via the second conduit assembly around the membrane.

[0044] According to some embodiments, the transfer of the produced catholyte solution is performed through the membrane.

[0045] According to some embodiments, the differential pressure on the membrane formed by the liquid pressure is between 150-250 mbar, to enable transfer of the produced catholyte solution through the membrane.

[0046] According to some embodiments, the pH level at the anolyte compartment is maintained at a value in the range of about 4-12.

[0047] According to some embodiments, the method further includes sensing, using a pH sensor, the pH level at one or more of: the catholyte compartment, the anolyte compartment, a wastewater tank, any outlet or inlet thereof, or any combination thereof.

[0048] According to some embodiments, the method further includes adding a make-up fluid to the catholyte tank or compartment from a make-up fluid source.

[0049] According to some embodiments, the method further includes collecting hydrogen gas produced during the treatment from the first valve or from the second conduit assembly.

[0050] According to some embodiments, the one or more contaminants includes ammonium.

[0051] According to some embodiments, the ammonium is converted to nitrogen gas during the treatment.

[0052] According to some embodiments, the method further includes collecting the treated wastewater.

[0053] According to some embodiments, the collection of the treated wastewater is from the anolyte outlet.

[0054] Certain embodiments of the present disclosure may include some, all, or none of the above advantages. One or more technical advantages may be readily apparent to those skilled in the art from the figures, descriptions and claims included herein. Moreover, while specificadvantages have been enumerated above, various embodiments may include all, some or none of the enumerated advantages.

[0055] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions.

[0056] BRIEF DESCRIPTION OF THE FIGURES

[0057] Some embodiments of the disclosure are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity, some objects depicted in the figures are not to scale.

[0058] In the figures:

[0059] FIGURE 1 - shows a general schematic illustration of an electrochemical wastewater treatment system and the flow of fluids therein, according to some embodiments;

[0060] FIGURE 2 - shows a schematic illustration of an electrochemical wastewater treatment system and the flow of fluids therein, according to some embodiments;

[0061] FIGURE 3 - shows a schematic illustration of an electrochemical wastewater treatment system and the flow of fluids therein, according to some embodiments;

[0062] FIGURE 4 - shows a schematic illustration of an electrochemical wastewater treatment system and the flow of fluids therein, according to some embodiments;

[0063] FIGURE 5 - shows a schematic illustration of an electrochemical wastewater treatment system and the flow of fluids therein, according to some embodiments;

[0064] FIGURE 6 - shows a schematic illustration of an electrochemical cell, according to some embodiments;

[0065] FIGURE 7 - shows a flowchart of steps of a method for treatment of wastewater and / or production of hydrogen gas, according to some embodiments;FIGURE 8 - shows a flowchart of steps of a method for treatment of wastewater and / or production of hydrogen gas, according to some embodiments;

[0066] FIGURE 9 - shows a line graph of the pH level and ammonia concentration in an anolyte and catholyte compartments during an electrochemical wastewater treatment that does not regulate the pH level in the anolyte compartment, according to some embodiments;

[0067] FIGURE 10 - shows a line graph of the ammonia level at the anolyte compartment and the pH level at the wastewater tank and anolyte compartment during the operation of an electrochemical wastewater treatment system 500, which includes bypassing the produced catholyte solution around a diaphragm membrane, according to some embodiments; and

[0068] FIGURE 11 - shows a line graph of the ammonia level at the anolyte compartment and the pH level at the wastewater tank and anolyte compartment during the operation of an electrochemical wastewater treatment system 600, which includes passing the produced catholyte solution through a diaphragm membrane from the catholyte compartment to the anolyte compartment, according to some embodiments.

[0069] DETAILED DESCRIPTION

[0070] In the following description, various aspects of the disclosure will be described. For the purpose of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the different aspects of the disclosure. However, it will also be apparent to one skilled in the art that the disclosure may be practiced without specific details being presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the disclosure.

[0071] Prior to setting forth the present subject matter in detail, it may be helpful to provide definitions of certain terms to be used herein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this subject matter pertains. The following definitions are provided for clarity.

[0072] The term "a" or "an" as used herein includes the singular and the plural, unless specifically stated otherwise. Therefore, the terms "a," "an", or "at least one" can be used interchangeably in this application.As used herein, the verb "comprise" as is used in this description and in the claims and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded.

[0073] As used herein, the term "about" when used in connection with a numerical value includes ±10% from the indicated value. In addition, all ranges directed to the same component or property herein are inclusive of the endpoints, are independently combinable, and include all intermediate points and ranges. It is understood that where a parameter range is provided, all integers within that range, and tenths thereof, are also provided by the invention.

[0074] As used herein, in accordance with some embodiments, the term “cation exchange membrane (CEM)” refers to a type of ion-exchange membrane that selectively allows cations (positively charged ions) to pass through while blocking anions (negatively charged ions). The membrane is used in various electrochemical processes, such as in fuel cells, batteries, and water purification / treatment systems. The semi-permeable membrane CEM consists of negatively charged moieties. According to some embodiments, sulfonic acid and carboxylic acid groups are nonlimiting examples of such negatively charged moieties.

[0075] As used herein, in accordance with some embodiments, the term “anolyte compartment” refers to one of the two main compartments in an electrochemical cell where the anode is located. The anolyte compartment contains an electrolyte solution that facilitates the flow of ions. Upon applying an electric field, oxidation reactions occur at the anode in the anolyte compartment. The oxidation generates oxidized species and cations. For example, ammonia (included in wastewater) can be oxidized to nitrogen gas. Examples of the generated cations may be protons. According to some embodiments, the anolyte compartment may include a “produced anolyte solution” that is acidic as a result of an accumulation of generated protons during oxidation. In some further embodiments, the anolyte compartment may include wastewater prior to treatment.

[0076] As used herein, in accordance with some embodiments, the term “catholyte compartment” refers to one of the two main compartments in an electrochemical cell where the cathode is located. The catholyte compartment contains an electrolyte solution that facilitates the flow of ions. Upon applying an electric field, reduction reactions occur at the cathode in the catholyte compartment. The reduction generates reduced species and anions. For example, in some embodiments, water molecules can be reduced to hydrogen molecules, and thegenerated anions may include hydroxide ions. According to some embodiments, the catholyte compartment may include a “produced catholyte solution” that is alkaline (characterized by a high pH level) as a result of the electrochemical reduction at the catholyte compartment. The catholyte compartment, in some embodiments, may further include pre-produced catholyte solution, i.e. electrolyte solution prior to application of an electric field.

[0077] As used herein, in accordance with some embodiments, the term “produced catholyte solution” refers to the solution produced at the catholyte compartment upon applying an electrical field between an anode and a cathode. According to some embodiments, the pH of the produced catholyte solution is above pH 12, for example, above pH 12.5, above 12.8, above pH 13, above pH 13.5, or above pH 14. Each possibility is a separate embodiment.

[0078] As used herein, in accordance with some embodiments, the terms “forced catholyte pump” and “bypass pump”, which may be used interchangeably, refer to one or more pumps that are configured to move / transfer fluid originating at the catholyte compartment (i.e., the “produced catholyte solution”), towards the anolyte compartment. In some embodiments, the one or more bypass pumps may be selected from, but is not limited to, rotary pump, compressor pump, centrifugal pump, peristaltic pump, gear pump, screw pump, diaphragm pump, positive displacement pump, and any combination thereof. Each possibility is a separate embodiment.

[0079] As used herein, in accordance with some embodiments, the term “catholyte tank” refers to a reservoir tank configured to receive and hold the produced catholyte solution. In some further embodiments, the catholyte tank is configured to receive make-up fluid. In some further embodiments, the catholyte tank is configured to output make-up fluid towards the catholyte compartment. In some further embodiments, the catholyte tank is configured to output the produced catholyte solution toward the anolyte compartment.

[0080] As used herein, in accordance with some embodiments, the term “catholyte pump” refers to a pump designed to move fluid from the catholyte compartment to the catholyte tank, and / or to move fluid from the catholyte tank to the catholyte compartment. According to some embodiments, the catholyte pump facilitates the transfer of fluid selected from, but not limited to, wastewater, produced catholyte solution, pre-produced catholyte solution (e.g., electrolyte), make-up fluid, make-up fluid-diluted produced catholyte solution (i.e., produced catholyte solution with make-up fluid), or a combination thereof. Each possibility is a separate embodiment. In some embodiments, the transfer is between the catholyte tank and the catholytecompartment. In some embodiments, a type of the catholyte pump may be selected from, but is not limited to, rotary pump, compressor pump, centrifugal pump, peristaltic pump, gear pump, screw pump, diaphragm pump, positive displacement pump, and any combination thereof. Each possibility is a separate embodiment.

[0081] As used herein, in accordance with some embodiments, the term “wastewater tank” refers to a reservoir of wastewater received to be treated. The tank may also refer to a vessel, container, chamber, reservoir, fluid-holding structure, natural reservoir, etc. In some embodiments, the wastewater tank receives and / or holds the wastewater. In some further embodiments, the wastewater tank outputs the wastewater towards the anolyte compartment for electrochemical treatment. In some further embodiments, the wastewater tank is configured to receive the transferred produced catholyte solution. In some embodiments, the wastewater tank is a source of a make-up fluid for the catholyte tank.

[0082] As used herein, in accordance with some embodiments, the term “wastewater pump” refers to a pump designed to move fluid from the wastewater tank to the anolyte compartment. In some embodiments, the wastewater pump may be selected from, but is not limited to, rotary pump, compressor pump, centrifugal pump, peristaltic pump, gear pump, screw pump, diaphragm pump, positive displacement pump, and any combination thereof. Each possibility is a separate embodiment.

[0083] As used herein, in accordance with some embodiments, the term “line” refers to any type of fluid-transferring conduit. According to some embodiments, the line may be, but is not limited to, a tube, a channel, or a pipe. Each possibility is a separate embodiment.

[0084] As used herein, in accordance with some embodiments, the term “conduit assembly” refers to one or more conduits, channels, pipes, tubes, hoses, pumps, valves, degassers, or passageways, and associated components, or any one or more functional units configured to transport, distribute, or convey a liquid fluid, gas, slurry, or other flowable material between two or more locations or components within a system. The conduit assembly may include one or more functional units, such as, but not limited to, connectors, valves, manifolds, junctions, pumps, or flow-control elements, and may be rigid or flexible, sealed or open, and formed from one or more materials. The conduit assembly may interchangeably be referred to as “conduit unit” or "conduit sub-system”.As used herein, in accordance with some embodiments, the term “valve” refers to a device or component configured to selectively control the passage of a fluid through a passage, conduit, or opening by movement, positioning, deformation, or actuation of at least one flowcontrol element. The valve may be operable in a closed state, in which passage of the fluid is prevented or substantially prevented; an open state, in which passage of the fluid is permitted; and one or more intermediate or partially closed states, in which passage of the fluid is restricted, regulated, or metered. The valve may be configured to control liquid fluids, gaseous fluids, vapors, or any combination thereof. The valve may be further configured to selectively permit passage of a gas while restricting or preventing passage of a liquid. Actuation of the valve may be mechanical, electrical, pneumatic, hydraulic, magnetic, or passive, and the valve may operate continuously, discretely, or proportionally.

[0085] As used herein, in accordance with some embodiments, the term “external alkaline agent” refers to a basic substance, molecule, polymer, compound, or salt added from an alkaline source outside the electrochemical system, i.e., from an alkaline source that is not part of the electrochemical system. The external alkaline agent's basic character may elevate an anolyte solution's pH level. Non-limiting examples of external alkaline agents may include, in some embodiments, NaOH, KOH, Ca(OH)2, or Mg(OH)2. Each possibility is a separate embodiment.

[0086] As used herein, in accordance with some embodiments, the term “specific energy consumption” refers to the amount of energy required to remove a specific amount of contaminant from the water (e.g., wastewater). In some embodiments, the specific energy consumption may be measured by kilowatt-hours per kilogram of nitrogen removed.

[0087] As used herein, in accordance with some embodiments, the term “contaminant” refers to a substance, molecule, polymer, compound, or salt that is present in a solution, (such as water or wastewater) or the atmosphere, and may be harmful to humans, animals or the environment and / or is targeted to be removed from the solution and / or atmosphere. Nonlimiting examples of contaminants may include, in some embodiments, urea or ammonia.

[0088] As used herein, in accordance with some embodiments, the term “oxidative intermediate product” refers to a product that is formed by the electrochemical oxidation of an initial reactant. In some embodiments, the ‘oxidative intermediate product’ may oxidize or partially oxidize a contaminant (e.g. ammonia).As used herein, in accordance with some embodiments, the term “initial reactant” refers to a substance, molecule, polymer, compound, or salt that enters, i.e., is introduced or present, in an anolyte compartment and is altered / changed in the course of an electrochemical reaction. In some embodiments, the ‘initial reactant’ may be transformed into an oxidative intermediate product. A non-limiting example of the initial reactant, in some embodiments, may include NaCl.

[0089] As used herein, in accordance with some embodiments, the term “non-contaminant specie(s)” refers to an entity (substance, molecule, polymer, compound, or salt) that is produced during the purification or separation process, such as contaminant removal process, e.g., removal of ammonia / ammonium). The non-contaminant specie(s) is essentially not considered harmful to organisms (such as humans or animals) or the environment. The non-contaminant specie(s) may be produced in a certain stoichiometric relationship with respect to the contaminant. In some embodiments, a contaminant may be converted to one or more noncontaminants during the process. A non-limiting example of non-contaminant specie(s) may include nitrogen gas.

[0090] As used herein, in accordance with some embodiments, the term “wastewater” refers to water that has been used and is no longer suitable for use unless treated. It typically contains one or more impurities, including biological, chemical, and physical contaminants, and originates from different sources. Non-limiting examples of wastewater may include, according to some embodiments, domestic wastewater, industrial wastewater, stormwater, agricultural wastewater, commercial wastewater, municipal wastewater, greywater, blackwater, and spent cell culture medium. The wastewater may include contaminant(s).

[0091] As used herein, in accordance with some embodiments, the term “diaphragm” refers to a thin barrier porous membrane between compartments and configured to separate and control interaction between them. The diaphragm may be permeable and configured to allow controlled passage of ions and liquid while minimizing passage of gas between the compartments.

[0092] As used herein, in accordance with some embodiments, the term “forced convective flux” refers to the transport rate (flux) of a species or fluid resulting from induced convection, wherein the motion of the fluid is generated by an applied force or mechanical means, such as a pump, pressure gradient, and / or imposed flow rather than by natural convection or diffusion alone. For example, closing catholyte outlet(s) to liquid may impose pressure and flow throughthe membrane and towards the anolyte compartment, which includes an anolyte outlet configured to output treated wastewater. The forced convective flux may contribute to mass transport by carrying dissolved, suspended, or entrained species, e.g., hydroxide ions, with the bulk fluid flow.

[0093] As used herein, in accordance with some embodiments, the symbol “ - ” refers in the drawing to an optional route / line. A combination of lines is possible. For instance, routes 60 and 65 or routes 61 and 62, may be combined, depending on system parameters, such as flow, concentration, membrane type, valve opening level, etc.

[0094] As used herein, in accordance with some embodiments, the term “hydraulic head” refers to the total mechanical energy per unit weight of water at a point in a fluid system, often interpreted as “how high water would rise” in a tightly connected piezometer tube. The hydraulic head may refer to a measure of pressure that is formed at the catholyte compartment when the outlet of the catholyte compartment is at least partially closed to liquid effluent. The term “pressure head” may refer to the height of a column of the same fluid that would produce the measured pressure at a point (i.e., pressure expressed as an equivalent fluid height).

[0095] As used herein, in accordance with some embodiments, the term “membrane” refers to a thin-layer structure forming a barrier between two fluid regions, configured to inhibit bulk mixing while permitting liquid transport across the barrier, wherein the transport may be through (i) pores of the structure and / or (ii) selective ion-conducting pathways. The term “membrane” may therefore include a porous diaphragm and / or an ion-exchange membrane, including a cation-exchange membrane.

[0096] As used herein, in accordance with some embodiments, the term “porous diaphragm” refers to a porous, fluid-permeable barrier having interconnected pores, positioned between two fluid regions to inhibit bulk mixing while allowing fluid to pass through the pores.

[0097] In an electrochemical wastewater treatment, pH changes occur during operation, with a reduction in pH level in the anolyte compartment. The acidic environment can cause corrosion or degrade membranes, thus reducing system efficiency. Therefore, the present disclosure relates to a system having a configuration that facilitates regulation of its pH level.

[0098] According to some embodiments, in the herein-disclosed electrochemical wastewater treatment system, at least a portion of the produced (alkaline) catholyte solution is transferredfrom a catholyte compartment to an anolyte compartment, thus increasing the pH level at the anolyte compartment.

[0099] In some embodiments, the transfer of the solution is performed via a conduit assembly that bypasses a membrane separating the compartments (e.g., an ion exchange membrane). In some embodiments, the transfer is performed via a forced convective force through the membrane (e.g., porous diaphragm). The system may be equipped with one or more pH sensors that allow (real-time) monitoring and regulation of the transfer. The transfer of the produced catholyte solution, therefore, may be performed according to a pH value determined in the wastewater reservoir tank, in the catholyte compartment, in the anolyte compartment, and / or in any inlet / outlet thereof.

[0100] There is provided herein, in accordance with some embodiments, an electrochemical wastewater treatment system that includes: an electrochemical cell including at least two liquid compartments, including an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in wastewater upon application of an electric field, and wherein the system is configured to transfer at least a portion of a catholyte solution produced at the catholyte compartment upon application of the electric field, towards the anolyte compartment, such that the pH level at the anolyte compartment is maintained at a value of at least pH 4.

[0101] Reference is now made to FIG. 1, which, according to some embodiments, schematically illustrates an electrochemical wastewater treatment system with pH regulation. As shown in FIG. 1, system 50 includes anolyte compartment 51 and catholyte compartment 52. Both compartments may include pH sensor(s) (not shown) inside, at their inlet, or at their outlet. In accordance with some embodiments, the two compartments are divided by a membrane 53, which can be a porous diaphragm or a cation exchange membrane.

[0102] According to some embodiments, system 50 includes a wastewater tank, serving as reservoir tank 54, and is configured to hold wastewater that may include ammonia. The system 50 may include a first conduit assembly fluidly connecting the wastewater tank 54 and the one or more electrochemical inlets. Accordingly, the wastewater may be introduced to the electrochemical cell through line 55. The wastewater tank 54 may include a pH sensor (not shown). According to some embodiments, the wastewater from the wastewater tank is transferred to one or more electrochemical cell inlets, i.e., the catholyte 52 and / or anolyte 51compartment inlets via the first conduit assembly, which includes line 55. The system, and more specifically the first conduit assembly, may include a wastewater pump 56 that facilitates the transfer of the wastewater to the compartment(s). According to some embodiments, the system includes a power supply 57 to generate an electrical field between an anode and a cathode of the anolyte and catholyte compartments, respectively, to generate an electrochemical reaction. As a result of the reaction, a catholyte solution is produced, meaning an electrolyte in the catholyte compartment 52 becomes more alkaline, according to some embodiments. This happens at the same time as the generation of hydrogen gas in the catholyte compartment 52. Further, during the operation of the cell, ammonia in the anolyte compartment 51 may be oxidized to nitrogen gas, and the pH level in the anolyte compartment 51 may be lowered.

[0103] The system 50 may include, according to some embodiments, one or more catholyte outlets. The one or more catholyte outlets may include a first catholyte outlet and / or a second catholyte outlet.

[0104] In some embodiments, the first catholyte outlet includes a first valve 58. The first valve 58 may be configured to selectively permit gas output from the catholyte compartment while preventing liquid output.

[0105] The one or more catholyte outlets may include a first valve 58, which can be configured to allow a flow of gas therethrough and reduce (or block) the flow of liquid. This can create hydraulic head in the catholyte compartment, which pressurizes the produced catholyte solution through the membrane to the anolyte compartment, to increase the pH in the anolyte compartment. Further, the valve may allow collecting the produced hydrogen gas from valve 58.

[0106] In some embodiments, the valve may allow output of a liquid effluent. In some embodiments, the valve may be closed to liquid effluent. In some embodiments, the valve may partially allow an output of liquid effluent. In some embodiments, the valve may be adjusted according to the system pH.

[0107] In some embodiments, the system may include a second catholyte outlet. The second catholyte outlet may include a second valve 59.The system may include a second conduit assembly, which is fluidly connected between the second catholyte outlet and the anolyte compartment inlet and / or the wastewater tank. The second conduit assembly may be positioned around the membrane.

[0108] The produced catholyte solution effluent coming out from the catholyte compartment outlet, via the second outlet of the catholyte outlet, may flow via the second conduit assembly through line 60. The conduit assembly may include a degassifier / gas-liquid separator (not shown) for the removal of dissolved and entrained hydrogen gas from the transferred produced catholyte solution. Further, the second conduit assembly may include a pump (not shown). The second conduit assembly may be connected to the anolyte compartment 51 and / or the wastewater tank 54.

[0109] The produced catholyte solution may further be transferred, e.g., via a recirculation pump (not shown) to the wastewater tank via line 61. This may allow introducing the alkaline produced catholyte solution to regulate the pH of the whole reservoir 54. The pH level may be monitored at the wastewater tank or at one of the inlets to the electrochemical cell, as well as at the anolyte compartment itself.

[0110] Alternatively, the produced catholyte solution may be transferred directly via the anolyte feed line 62, i.e., to the anolyte inlet, utilizing an in-line static mixer for immediate integration, to increase the pH in the anolyte compartment 51.

[0111] According to some embodiments, the system may include a first catholyte valve 58, which is partially closed or closed to liquid, and the second catholyte outlet 60 or valve 59 may be absent.

[0112] According to some embodiments, the system may include a second catholyte outlet, which is connected to the second conduit assembly. The first catholyte outlet 65 may be absent.

[0113] According to some embodiments, the system may include both the first and the second catholyte outlets or valves, thus creating hybridization of mechanisms to transfer the produced catholyte solution to the anolyte compartment. In such a hybrid system, the produced catholyte solution may be transferred towards the anolyte compartment both through the membrane 53 and around the membrane 60.In some embodiments, the produced catholyte solution may be transferred towards the anolyte compartment mainly through the membrane 53 and minorly around the membrane 60.

[0114] In some embodiments, the system includes the first catholyte outlet and the first valve. The system may further include the second outlet, which may include a flow regulator, e.g., a second valve. The first valve allows gas release therethrough and prevents liquid effluent, which increases the hydraulic head in the catholyte compartment that, in turn, facilitates the transfer of the produced catholyte solution through the membrane. The second outlet may allow a limited flow rate of liquid effluent towards the second conduit assembly to the anolyte compartment around the membrane. The flow through the second outlet may be regulated by the second valve, not to compromise the hydraulic pressure required to push produced catholyte solution through the membrane.

[0115] The system may include an anolyte outlet 63 to enable the collection of the treated wastewater from the anolyte compartment. The treated wastewater may be collected from the wastewater tank.

[0116] There is provided herein, in accordance with some embodiments, an electrochemical wastewater treatment system that includes: an electrochemical cell including at least two liquid compartments, including an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in wastewater upon application of an electric field, and wherein the membrane is a porous diaphragm configured to transfer therethrough at least a portion of a catholyte solution produced at the catholyte compartment upon application of the electric field, towards the anolyte compartment, such that the pH level at the anolyte compartment is maintained at a value of at least pH 4.

[0117] There is provided herein, in accordance with some embodiments, an electrochemical wastewater treatment system that includes: an electrochemical cell including at least two liquid compartments, including an anolyte compartment and a catholyte compartment separated by a cation exchange membrane (CEM), wherein the anolyte compartment is configured to oxidize contaminants in wastewater upon application of an electric field; and a bypass pump configured to transfer at least a portion of a catholyte solution produced at the catholyte compartment upon application of the electric field, towards the anolyte compartment, such that the pH level at the anolyte compartment is maintained at a value of at least about pH 5.According to some embodiments, the pH value at the anolyte compartment is configured to be maintained at a value in the range of about pH 4-12, for example, about pH 5-12, about pH 4-11, about pH 4-10, about pH 6-9, or about pH 6-8. Each possibility is a separate embodiment. According to some embodiments, the pH value at the anolyte compartment is configured to be maintained at a value in the range of about pH 4-9.

[0118] According to some embodiments, the electrochemical cell is a divided cell configuration. Advantageously, by utilizing a produced catholyte solution in the anolyte compartment, the divided cell may result in: 1. treated water with reduced ammonia level and / or 2. recovery of hydrogen product, possibly in high purity. These can be efficiently achieved using a reduced or no amount of exogenously added consumables to increase the pH level in the anolyte compartment, in order to maintain system operation.

[0119] According to some embodiments, the amount of external alkaline agent required to neutralize the total anolyte solution is below 2 molOH / molN, for example, below 1.5 molOH / molN, below 1 molOH / molN, or below 0.8 molOH / molN. Each possibility is a separate embodiment.

[0120] According to some embodiments, the catholyte compartment includes an output configured to output produced hydrogen gas.

[0121] According to some embodiments, the system includes a catholyte tank, which includes an output configured to output produced hydrogen gas.

[0122] In some embodiments, at least one or more pH sensors is functionally associated with the second conduit assembly and / or the second catholyte outlet valve and are configured to directly or indirectly regulate the transfer of at least a portion of the produced catholyte solution by bypassing the membrane to the anolyte compartment, based on the measured pH level.

[0123] In some embodiments, at least one or more pH sensors is functionally associated with the first catholyte outlet valve and / or the first conduit assembly and are configured to indirectly or directly regulate the transfer of at least a portion of the produced catholyte solution through the membrane, based on the measured pH level. The fluid flow and the pressure may be regulated based on the pH level.There is provided, in accordance with some embodiments, an electrochemical wastewater treatment system comprising:

[0124] an electrochemical cell comprising at least two liquid compartments, comprising an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in the wastewater upon application of an electric field;

[0125] a wastewater tank connected via a first conduit assembly to feed electrochemical cell one or more inlets;

[0126] an anolyte outlet, configured to output treated wastewater product; and

[0127] one or more catholyte outlets comprising configured to allow output of a produced catholyte solution, formed upon the application of the electric field, the outlet being connected to a second conduit assembly bypassing the membrane, the second conduit assembly is further connected to the one or more inlets of the electrochemical cell and / or the wastewater tank, and is configured to transfer at least a portion of the produced catholyte solution towards the anolyte compartment and / or the wastewater tank,

[0128] such that the pH level at the anolyte compartment is configured to be maintained at a value of at least about pH 4, or the total external alkaline agent required to neutralize the produced anolyte solution is below 2 molhOH / molN.

[0129] In some embodiments, the membrane is a diaphragm. In some embodiments, the membrane is a cation exchange membrane (CEM).

[0130] In some embodiments, the CEM includes moieties of sulfonate, carboxylate, and / or phosphonate. Each possibility is a separate embodiment.

[0131] According to some embodiments, the CEM is a perfluorinated membrane. The CEM may be chemically stabilized by the perfluorinated backbone. The CEM may be a perfluorinated membrane that includes moieties of sulfonate, carboxylate, and / or phosphonate. The perfluorinated backbone of the CEM may stabilize the membrane in an oxidative environment, such as in wastewater, which may contain oxidative species, e.g., an oxidative intermediate product (e.g., hypochlorite).The CEM may be selected from, but not limited to, Nafion, Flemion (AGC), Aquivion (Solvay), Fumapem (FuMA-Tech), or Pemion (Ionomer Innovations). Each possibility is a separate embodiment.

[0132] The CEM may be Nafion.

[0133] In some embodiments, the Nafion may be N115, N117, N1110, NR211, NR212, N966, N982, N2030, N2050, or N2060. Each possibility is a separate embodiment.

[0134] According to some embodiments, when the membrane is a cation exchange membrane, the pH at the anolyte is maintained above pH 4. According to some embodiments, when the membrane is a porous diaphragm, the total external alkaline agent required to neutralize the produced anolyte solution is below 2 molhOH / molN.

[0135] Reference is now made to FIG. 2, which, according to some embodiments, schematically illustrates an electrochemical wastewater treatment system with inherent pH regulation. As shown in FIG. 2, system 500 includes anolyte compartment 501 and catholyte compartment 502. Both compartments may include pH sensor(s) (not shown) inside, at their inlet or at their outlet. In accordance with some embodiments, the two compartments are divided by a membrane 503, which can be a porous diaphragm or a cation exchange membrane. According to some embodiments, in system 500, a wastewater tank, serving as reservoir tank 504, is configured to hold wastewater entering the electrochemical cell through line 510. The wastewater tank may include a pH sensor (not shown). The system 500 may include a first conduit assembly fluidly connected to the wastewater tank 504 and the one or more electrochemical inlets. According to some embodiments, the wastewater from the wastewater tank is transferred to the catholyte 502 and anolyte 501 compartment inlets (i.e., the one or more electrochemical cell inlets) through line 511, i.e, of the first conduit assembly. The first conduit assembly may include a wastewater pump 512, which may facilitate the transfer to the compartment(s). According to some embodiments, the system includes a power supply 513 to generate an electrical field between an anode and a cathode of the anolyte and catholyte compartments, respectively. As a result of supplying the power, a catholyte solution is produced, meaning an electrolyte in the catholyte compartment 502 becomes more alkaline, according to some embodiments. This happens at the same time as the generation of hydrogen gas in the catholyte compartment 502.The one or more catholyte outlets of the system may include a (second) catholyte outlet. The catholyte outlet may include a (second) valve. The catholyte second outlet may be connected to a second conduit assembly, which is further connected to the wastewater tank and / or the anolyte compartment inlet. Accordingly, the effluent coming out from the catholyte compartment outlet (e.g., via the second valve of the catholyte outlet) may flow via line 514 via a second conduit assembly towards the wastewater tank and / or the anolyte compartment. The conduit assembly may include a degassifier / gas-liquid separator 515 for the removal of dissolved and entrained hydrogen gas from the transferred produced catholyte solution. In some embodiments, the degassing increases gas purity and safety during recirculation of the produced catholyte solution. The produced catholyte solution may further be transferred via a recirculation pump 516 to the wastewater tank via line 517. This may allow introducing the alkaline produced catholyte solution to the tank 504 to regulate the pH of the whole reservoir. The pH level may be monitored at the wastewater tank or at one of the inlets to the electrochemical cell, as well as at the anolyte compartment itself.

[0136] Alternatively, or in addition, the (degassed) produced catholyte solution may be transferred directly via the anolyte feed line 518, i.e., to the anolyte inlet, utilizing an in-line static mixer for immediate integration.

[0137] The pH regulation is inherently achieved in the system by transferring the produced catholyte solution to the anolyte compartment. The system may require minimal or no addition of external alkaline agent.

[0138] The treated wastewater can be collected from the anolyte compartment outlet through line 520 or from the wastewater tank 504 after several circulations in the system.

[0139] In some embodiments, at least a portion of the produced catholyte solution is configured to be transferred by the second conduit assembly directly from the catholyte compartment to the anolyte compartment.

[0140] In some embodiments, at least a portion of the produced catholyte solution is configured to be transferred by the second conduit assembly to the wastewater tank.

[0141] In some embodiments, at least a portion of the produced catholyte solution is configured to be transferred to the catholyte tank and transferred therefrom to the wastewater tank.In some embodiments, the second conduit assembly is connected to the catholyte tank or catholyte compartment such that at least a portion of the produced catholyte solution is configured to be transferred thereby from the catholyte tank / compartment towards the anolyte compartment.

[0142] There is provided, in accordance with some embodiments, an electrochemical wastewater treatment system comprising:

[0143] an electrochemical cell comprising at least two liquid compartments, comprising an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in the wastewater upon application of an electric field;

[0144] a wastewater tank connected via a first conduit assembly to one or more inlets of the electrochemical cell;

[0145] an anolyte outlet, configured to output a treated wastewater; and

[0146] one or more catholyte outlets comprising a first valve configured to reduce amount of liquid effluent from the catholyte compartment, thereby forming a hydraulic head in the catholyte compartment that pressurizes at least a portion of the produced catholyte solution, formed upon the application of the electric field, through the membrane to the anolyte compartment,

[0147] such that the pH level at the anolyte compartment is configured to be maintained at a value of at least about pH 4.

[0148] There is provided, in accordance with some embodiments, an electrochemical wastewater treatment system comprising:

[0149] an electrochemical cell comprising at least two liquid compartments, comprising an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in the wastewater upon application of an electric field;

[0150] a wastewater tank connected via a first conduit assembly to one or more inlets of the electrochemical cell;

[0151] an anolyte outlet, configured to output a treated wastewater; andone or more catholyte outlets comprising a first valve configured to selectively permit a gas output from the catholyte compartment, thereby facilitating a liquid pressure in the catholyte compartment that directs passage of at least a portion of a catholyte solution produced upon the application of the electric field, through the membrane to the anolyte compartment,

[0152] such that the pH level at the anolyte compartment is configured to be maintained at a value of at least about pH 4.

[0153] According to some embodiments, the membrane is a porous diaphragm.

[0154] According to some embodiments, the membrane is a cation exchange membrane that is capable of at least partially transporting hydroxide ions from the catholyte compartment to the anolyte compartment, for example, under suitable pressure and sufficient hydroxide concentration.

[0155] In some embodiments, the membrane may be a bipolar exchange membrane.

[0156] According to some embodiments, the required alkaline agent required to neutralize the total produced anolyte solution is less than 1.5 molOH / molN, for example, less than 1 molOH / molN, or less than 0.5 molOH / molN. Each possibility is a separate embodiment.

[0157] In some embodiments, the first valve of the catholyte outlet is closed or nearly closed to liquid flow, to allow back pressure from the catholyte compartment towards the anolyte compartment through the membrane, i.e., creating a pressure vector across the membrane.

[0158] In some embodiments, the first valve of the catholyte outlet is open to gas flow and is configured to output hydrogen gas produced by the system. The valve may be closed to liquid effluent.

[0159] In some embodiments, the membrane is microporous, thereby enabling the produced catholyte solution liquid, including the hydroxide ions, to pass therethrough towards the anolyte compartment.

[0160] In some embodiments, the porous diaphragm may have pores having an average size of between 0.1-0.45 μm. Preferably, the pores of the porous diaphragm have an average size between 0.15 μm and 0.25 μm. In some embodiments, the pores of the porous diaphragm have an average size of 0.2-0.25 μm.In some embodiments, the porous diaphragm may be made of poly(vinylidene fluoride) (PVDF), Polytetrafluoroethylene (PTFE), polypropylene (PP), and / or polyethylene (PE). Each possibility is a separate embodiment. In some embodiments, the porous diaphragm is made of PVDF and has pores of about 0.2 μm.

[0161] In some embodiments, the porous diaphragm comprises a fluorinated polymer. The fluorinated polymer may be robust under the oxidative conditions during the wastewater treatment. In some embodiments, the porous diaphragm includes poly(vinylidene fluoride) (PVDF). In some embodiments, the porous diaphragm includes Polytetrafluoroethylene (PTFE).

[0162] In some embodiments, a hydraulic head formed by reduced liquid effluent from the catholyte compartment facilitates a differential pressure on the membrane of between 150-250 mbar, for example, 180-250 mbar, 150-220 mbar, 180-220 mbar, or about 200 mbar. Each possibility is a separate embodiment.

[0163] Reference is now made to FIG. 3, which schematically illustrates an electrochemical wastewater treatment system with inherent pH regulation, according to some embodiments. System 600 includes an anolyte compartment 601 and a catholyte compartment 602. Both compartments may include pH sensor(s) (not shown). In accordance with some embodiments, the two compartments are divided by a porous diaphragm membrane 603. The diaphragm may be permeable to hydraulic flow.

[0164] The diaphragm facilitates the transfer of liquid, such as the produced catholyte solution, including the hydroxide ions, from the catholyte 602 to the anolyte 601 compartment. The diaphragm provides a barrier to gas bubbles, i.e., it minimizes the transfer of gas, such as hydrogen, from the catholyte 602 to the anolyte 601 compartment. The gas separation in the diaphragm may be achieved through the surface tension of the electrolyte filling its microscopic pores. As long as the pores remain smaller than the potential gas bubbles and / or are fully wetted, the liquid acts as a physical seal, preventing or minimizing gas crossover up to a specific differential pressure. The differential pressure may be about 200 mbar.

[0165] In some embodiments, the diaphragm may be made of a robust polymer or a ceramic-polymer composite that is resistant to the corrosive conditions present in brine and wastewater electrolysis (e.g., chlorine species).In some embodiments, the porous diaphragm may be made of poly(vinylidene fluoride) (PVDF), Polytetrafluoroethylene (PTFE), polypropylene (PP), polyethylene (PE), ceramics, glass, stainless steel, or any composite thereof. Each possibility is a separate embodiment.

[0166] According to some embodiments, system 600 includes a wastewater tank, serving as reservoir tank 604, is configured to hold wastewater entering the system through line 610. The wastewater tank may include a pH sensor (not shown). According to some embodiments, the system includes a first conduit assembly, including line 611, connecting the wastewater tank and the one or more inlets of the electrochemical cell. Accordingly, the wastewater from the wastewater tank may be transferred to the anolyte and / or catholyte compartment inlets through the first conduit assembly via line 611. A wastewater pump 605 may facilitate the transfer from the tank 604 to the electrochemical cell compartments 601 and / or 602. According to some embodiments, the system includes a power supply 614 to generate an electrical field between an anode and a cathode of the anolyte and catholyte compartments, respectively. As a result of supplying the power, a catholyte solution is produced in the catholyte compartment 602, meaning an electrolyte in the catholyte compartment becomes more alkaline, according to some embodiments. This occurs simultaneously with the generation of hydrogen gas in the catholyte compartment 602.

[0167] The system includes, according to some embodiments, a (first) outlet of the catholyte compartment, which may include a first valve 606. The first valve can be closed or partially closed for liquid flow, by being, for example, a proportional valve. The valve may remain open for gas. Accordingly, the hydrogen gas produced at the catholyte compartment is output through line 612. Concurrently, minimal or no output of liquid effluent is enabled from the catholyte compartment. As a result, a pressure of liquid may be formed in the catholyte compartment 602, such that the produced catholyte solution is forced through the pores of the diaphragm 603 into the anolyte compartment 601. In this configuration, the catholyte outlet 612 may be restricted to discharging mostly hydrogen gas, while the liquid carrying the generated hydroxyl ions may be directed into the oxidation zone 601 to increase pH level of the produced anolyte solution.

[0168] In some embodiments, the system further includes an anolyte outlet. In this mode, wastewater enters compartments 601 and / or 602, but the hydraulic design forces most of theliquid phase to move through the diaphragm towards the anolyte compartment 601, and afterward to the anolyte outlet, i.e., towards line 613. This allows operators to maintain a higher pressure on the cathode side, forcing alkaline catholyte through the diaphragm into the anode. This convective flow may physically sweep cathodic hydroxide ions into the oxidation zone to neutralize anodic protons in-situ, thus significantly lowering external chemical demand.

[0169] In some embodiments, the system maintains the Trans-Membrane Pressure (TMP) on the porous diaphragm 603 to ensure liquid moves through the diaphragm with minimum gas breakthrough.

[0170] In some embodiments, the TMP value is between 100-300 mbar, for example, 150-250 mbar, 100-250 mbar, 150-300 mbar, 180-220 mbar, or about 200 mbar. Each possibility is a separate embodiment. The pressure may be maintained by the porous or material design of the membrane, which dictates the bubble point at which the produced gas is prevented from passing the membrane. For example, the bubble point for a 0.2 μm PVDF diaphragm may be in the range of 3.8-4.1 bar. Therefore, the TMP is kept below this point. As used herein, the term “bubble point” may refer to a minimum pressure required to force a gas to pass through a liquid-wetted membrane, causing the first continuous stream of bubbles to appear on the other side of the membrane.

[0171] In some embodiments, the pore size and hydrophilicity of the diaphragm 603 are suitable to allow the transfer of the produced catholyte solution across the membrane, while limiting the transfer of gas. Accordingly, the diaphragm thus stands within the limits of TMP on the membrane 603 and / or the bubble point required for such transfer.

[0172] A sufficient hydraulic head may be established at the catholyte compartment. The liquid in the catholyte compartment is prevented from exiting the cathode compartment via the standard liquid port, i.e., the catholyte outlet, but is capable of passing through the membrane.

[0173] The system may further include an anode proportional valve 607 at the anolyte compartment outlet line 613. This valve may serve as a stabilizer. It can maintain a minimum counter-pressure in the anolyte compartment 601 to prevent the diaphragm 603 from "gasbinding" and to regulate the residence time of the wastewater within the oxidation zone 601.

[0174] In some embodiments, the system may include a Differential Pressure (ΔP) Transmitter, which provides real-time measurement of the pressure gradient between the catholyte 602 andanolyte 601 compartments. Monitoring of the pressure may facilitate control over the pH, gas level, purity of the gas, and yield and quality of treated water.

[0175] The system may further include a treated wastewater collection tank 608, which receives the treated wastewater from the anolyte compartment 601.

[0176] In some embodiments, the system may include a Hydrogen H2Crossover Sensor 609 at the anolyte outlet (not shown) or at the treated wastewater collection tank. The sensor may monitor the anolyte gas phase for trace hydrogen, serving as a safety indicator for gas breakthrough. The sensor may detect if the pressure from the catholyte compartment, i.e., the differential pressure (ΔP), has exceeded the diaphragm's "bubble point," preventing the formation of explosive gas mixtures in the anolyte compartment 601.

[0177] According to some embodiments, the purity of the hydrogen gas produced by the system may be above 85%, for example, above 87%, above 90%, or above 95%. Each possibility is a separate embodiment. The diaphragm may partially allow gas crossover, however, adjusting flux by system configuration, as noted hereinabove, may further tune the purity level.

[0178] In some embodiments, the diaphragm in the system, including hydraulic pressure, such as in system 600, may have a reduced crossover of gas originating at the anolyte compartment (e.g., gas of nitrogen or ammonia). The pressure towards the side of the anolyte compartment may prevent gas from crossing into the catholyte compartment. As a result, the hydrogen purity may increase.

[0179] In some embodiments, the purity of the produced hydrogen gas may be above 95%, for example, above 97%, above 99%, or above 99.5%. Each possibility is a separate embodiment. For instance, an ion exchange membrane, as detailed herein below, may further minimize the crossover of the gas through the membrane and thus increase the purity level of the produced hydrogen gas.

[0180] Reference is now made to FIG. 4, which schematically illustrates an electrochemical wastewater treatment system with pH regulation, according to some embodiments. As shown in FIG. 4, system 100 includes an anolyte compartment 101 and a catholyte compartment 102.

[0181] Both compartments may include pH sensor(s) (not shown). In accordance with some embodiments, the two compartments are divided by a cation exchange membrane (CEM) 103.According to some embodiments, in system 100, a wastewater tank, serving as reservoir tank 104 is configured to hold wastewater entering the system through line 110. The wastewater tank may include a pH sensor (not shown). According to some embodiments, the wastewater from the wastewater tank is transferred to the anolyte compartment through line 111. A wastewater pump may facilitate the transfer (not shown). According to some embodiments, the system includes a power supply 105 to generate an electrical field between an anode and a cathode of the anolyte and catholyte compartments, respectively. As a result of supplying the power, a catholyte solution is produced, meaning an electrolyte in the catholyte compartment becomes more alkaline, according to some embodiments. This happens at the same time as the generation of hydrogen gas in the catholyte compartment.

[0182] According to some embodiments, at least a portion of the produced catholyte solution is transferred through line 112a to a catholyte tank 106 and then further transferred through line 112b towards the anolyte compartment. The catholyte tank may include a pH sensor (not shown). According to some embodiments, the produced catholyte solution is alternatively, or in addition, transferred through line 113 towards the anolyte compartment, while skipping the catholyte tank. The produced catholyte solution is further configured, in accordance with some embodiments, to be transferred from the catholyte tank and / or from the catholyte compartment towards the anolyte compartment via line 114. According to some embodiments, the system further includes a bypass pump 107 that is configured to move the produced catholyte solution towards the anolyte compartment via line 115. In some embodiments, the bypass pump may include, for example, a positive displacement pump. In some embodiments, the produced catholyte solution may be transferred through line 116 directly to the anolyte compartment. Alternatively, and / or in addition, according to some embodiments, the produced catholyte solution may be transferred through line 117 to the wastewater tank prior to reaching the anolyte compartment. The transfer is regulated by the pH sensor(s), the bypass pump, and / or one or more valve(s), according to some embodiments. In some embodiments, the one or more valves may include, for example, a solenoid valve. The one or more valves may be used to open or close any of the lines based on predetermined pH setpoints / thresholds.

[0183] According to some embodiments, line 118 of the system is configured to introduce make-up fluid to the catholyte tank from a make-up fluid source 108. According to some embodiments, content of the catholyte tank, that may include the make-up fluid, can be directed to the catholyte compartment through line 119. A catholyte pump associated with the line (notshown) may facilitate this transfer. In some embodiments, the make-up fluid source may include, but not limited to, wastewater, treated water, water including salt, or any combination thereof. In some embodiments, the wastewater make-up fluid may originate from the wastewater tank. According to some embodiments, an additional optional line 120 may fluidly connect between the make-up fluid source and a wastewater source or the wastewater tank. In some embodiments, the wastewater tank may be fluidly connected to the catholyte compartment and / or the catholyte tank. The make-up fluid is intended to compensate for loss of fluid volume and / or salt at the catholyte compartment during the process (i.e. electrolyte source). According to some embodiments, treated wastewater that is produced by the electrochemical system (i.e., resulting from the purification process) is output through line 121.

[0184] Reference is now made to FIG. 5 which schematically illustrates an exemplifying electrochemical wastewater treatment system with pH regulation, according to some embodiments. As shown in FIG. 5, system 200 includes an anolyte compartment 201 and a catholyte compartment 202. Both compartments may be associated with pH sensors (not shown). In accordance with some embodiments, the two compartments are divided by a cation exchange membrane (CEM) 203. According to some embodiments, in system 200, a wastewater tank, serving as a reservoir tank, 204 is configured to hold wastewater entering the system through line 210. The wastewater tank may be associated with a pH sensor (not shown). According to some embodiments, the wastewater, from the wastewater tank, is transferred to the anolyte compartment through line 211. A wastewater pump 205, (for example, a centrifugal pump), may facilitate the transfer of the wastewater from the wastewater tank to the anolyte compartment.

[0185] According to some embodiments, the system includes a power supply 206 to generate an electrical field between an anode and a cathode of the anolyte and catholyte compartments, respectively. As a result of supplying the power, a catholyte solution is produced, i.e. an electrolyte in the catholyte compartment becomes more alkaline, according to some embodiments. This happens at the same time as the generation of hydrogen gas in the catholyte compartment.

[0186] According to some embodiments, at least a portion of the produced catholyte solution is transferred from the catholyte compartment through line 212 to a catholyte tank 207 and then further transferred through line 213 towards the anolyte compartment. According to some embodiments, the system further includes a bypass pass (i.e., forced catholyte pump) 208, suchas a rotary compressor pump, that is configured to move the produced catholyte solution towards the anolyte compartment via line 213. According to some embodiments, the produced catholyte solution is transferred through line 213 to the wastewater tank prior to reaching the anolyte compartment via line 211. Line 214 of the system is configured to allow the introduction of a make-up fluid from a make-up fluid source to the catholyte tank, according to some embodiments. According to some embodiments, content of the catholyte tank, that may include the make-up fluid, can be directed to the catholyte compartment through line 215.

[0187] The transfer from the catholyte tank to the catholyte compartment may be facilitated by a catholyte pump, such as a centrifugal pump 209. In some embodiments, the make-up fluid source may include, but not limited to, wastewater, treated water treated water including salt, or any combination thereof. In some embodiments, the wastewater may originate from the wastewater tank or from another wastewater source. The make-up fluid is intended to compensate for loss of fluid volume at the electrochemical cell during the process. According to some embodiments, treated wastewater that is produced by the electrochemical system is output through line 216.

[0188] According to some embodiments, the conduit assembly, which may include a bypass pump, is configured to transfer at least a portion of the produced catholyte solution, when the pH of the produced catholyte solution is above a predetermined threshold. In some embodiments, the predetermined threshold is at least about pH 12-14, for example, at least about pH 12.5-14, at least about pH 12.5-13.5, or at least about pH 13-14. Each possibility is a separate embodiment.

[0189] According to some embodiments, the conduit assembly, which may include a bypass pump, is configured to transfer at least a portion of the produced catholyte solution towards the anolyte compartment and / or the wastewater tank, when the pH of the anolyte solution and / or the wastewater solution at the wastewater tank is below a predetermined threshold. According to some embodiments, at least a portion of the produced catholyte solution is transferred towards the anolyte compartment and / or the wastewater tank, when the pH of the anolyte solution and / or the wastewater solution at the wastewater tank is below a predetermined threshold. In some embodiments, the predetermined threshold is less than about pH 6, for example, less than about pH 5.5, less than about pH 5, less than about pH 4.5, less than about pH 4, less than about pH 3.5, less than about pH 3, or less than about 2.5. Each possibility is a separate embodiment.According to some embodiments, the electrochemical wastewater treatment system includes an electrochemical cell, wherein two half-reactions occur during operation. Reference is made to FIG. 6 which schematically illustrates in 300 an exemplary electrochemical cell for wastewater treatment, specifically for ammonia removal (i.e., ammonium ions) by oxidation of ammonium to nitrogen gas. The inert nitrogen gas may then escape the system. In some embodiments, an oxidation reaction occurs at an anode electrode 301 of the anolyte compartment. In some embodiments, the oxidation reaction includes the oxidation of wastewater. In some embodiments, the oxidation reaction includes the oxidation of ammonium ions (NH4+). In some embodiments, the oxidation of ammonium ions takes place as follows: 2NH4+— >-N2+6e'+8H+. In some embodiments, the oxidation of the ammonium ions may be obtained by a direct electrooxidation. In some embodiments, the oxidation of the ammonium ions may be obtained by an indirect electrooxidation. In some embodiments, an oxidative intermediate product that are formed via electrooxidation may chemically oxidize the ammonium ions and produce nitrogen gas. In some embodiments, splitting of water (i.e. Oxygen Evolution Reaction OER) takes place as follows 2H2O→ O2+4e-+4H+). The products of the oxidation reaction at the anolyte include nitrogen gas (N2), oxygen gas (O2) and protons (H+).

[0190] According to some embodiments, the oxidative intermediate product is produced at the anode via an electro-oxidation of an initial reactant. According to some embodiments, the initial reactant undergoes electro-chlorination. According to some embodiments, the one or more contaminants undergoes indirect electrochemical oxidation. According to some embodiments, the one or more contaminants undergoes chloro-amination.

[0191] According to some embodiments, reactions utilizing the initial reactant undergo via, but are not limited to, reaction (1), the initial reactant is labeled in bold:

[0192] (1) 2Cl-→ Cl2+ 2e-

[0193] According to some embodiments, reactions towards the production of the oxidative intermediate products undergo via but are not limited to reactions (1-6), the oxidative intermediate products are labeled in bold:

[0194] (1) 2Cl-→ Cl2+ 2e-

[0195] (2) 3Cl2+ NH4+→ NCl3+ 3Cl-+ 4H+

[0196] (3) NCl3+ OH-→ NHCl2+ OCl-(4) Cl2+ NHCl2→ NCl3+ Cl-+ H+

[0197] (5) 2Cl2+ NH2Cl → NCl3+ 2Cl-+ 2H+

[0198] (6) NCl3+ NHCl2+ 5OH-→ N2+ 2OCl-+ 3Cl-+ H2O

[0199] According to some embodiments, reactions utilizing the oxidative intermediate product may undergo via, but are not limited to, reactions (2-6), the oxidative intermediate product are labeled in bold:

[0200] (2) 3Cl2+ NH4+→ NCl3+ 3Cl-+ 4H+

[0201] (3) NCl3+ OH-→ NHCl2+ OCl-

[0202] (4) Cl2+ NHCl2→ NCl3+ Cl-+ H+

[0203] (5) 2Cl2+ NH2Cl → NCl3+ 2Cl-+ 2H+

[0204] (6) NCl3+ NHCl2+ 5OH-→ N2+ 2OCl-+ 3Cl-+ H2O

[0205] According to some embodiments, reactions for the production of a non-contaminant specie(s), such as nitrogen gas, may undergo via, but are not limited to reaction (6), the noncontaminant is labeled in bold:

[0206] (6) NCl3+ NHCl2+ 5OH-→ N2+ 2OCl-+ 3Cl-+ H2O

[0207] According to some embodiments, reactions utilizing the one or more contaminants undergo via, but are not limited to, reaction (2), the one or more contaminants is labeled in bold:

[0208] (2) 3Cl2+ NH4+→ NCl3+ 3Cl-+ 4H+

[0209] According to some embodiments, the overall oxidation can be described as follows (7) NH4+→ ½N2+ 3e-+ 4H+

[0210]

[0211] +

[0212] The subsequent decomposition of chloramines to N2 gas results in a cumulative theoretical "acid debt" of approximately 4 moles of H+per 1 mole of Nitrogen removed (molN).

[0213] According to some embodiments, during the operation of the electrochemical cell, the increase of proton concentration essentially lowers the pH level at the anolyte compartment.

[0214] According to some embodiments, a reduction reaction occurs at the cathode electrode 303 of the catholyte compartment, during the operation of the electrochemical cell. In someembodiments, the reduction reaction at the catholyte compartment produces the produced catholyte solution. In some embodiments, the reduction reaction includes a reduction of water molecules. In some embodiments, the reduction reaction is as follows: 6H2O+6e-→3H2+6OH-. According to some embodiments, the reduction reaction results in hydroxide ions. In some embodiments, an increase in hydroxide ions in the catholyte compartment results in an increase in the pH level at the catholyte compartment, during / upon the operation of the electrochemical cell.

[0215] In some embodiments, the anolyte and catholyte compartments are separated by a membrane 302 such as cation exchange membrane (CEM) or diaphragm.

[0216] Simultaneously, the reduction of water at the cathode serves as an in-situ generator of alkalinity. The overall cathodic reaction can be described as follows:

[0217] (8) 3H2O + 3e-→ ³⁄₂H2+ 3OH-

[0218]

[0219] Applying Faraday’s Law (three electrons needed to fully oxidize ammonia to nitrogen gas), the cathode generates 3 moles of OH" (molOH") per mole of ammonia oxidized.

[0220] Accordingly, a theoretical chemical consumption required to neutralize the acid may be calculated and the efficiency may be quantified by the molar ratio of external hydroxide required to maintain neutral stability (molOH' / molN) in an anolyte compartment. The theoretical chemical consumption for undivided cell configuration, for example, may be 1 molOH / molN. This occurs spontaneously by recombination of anodic H+ and cathodic OH-. In contrast, the theoretical chemical consumption for a divided cell configuration (without utilizing the produced catholyte solution) is 4 molOH / molN, provided mainly from external chemical OH- compensation into the anolyte compartment. However, the theoretical chemical consumption for a divided cell configuration utilizing recycled produced catholyte solution may be 1 molOH / molN. This is achieved by actively transporting the produced catholyte solution to the anolyte compartment or influent stream for buffering the pH in the anolyte compartment. Accordingly, the system leverages the internally generated alkalinity at the catholyte compartment to neutralize the anolyte acidity, thereby minimizing dependency on external chemicals.

[0221] In some embodiments, the system may include a buffer in the anolyte and catholyte compartments, which inherently may be present in the wastewater or that is externally addedto the system. The buffer may be at a pH level between pH 6 and 10. The buffer may vary in its buffer capacity. Thus, the theoretical chemical consumption for a system which includes a buffer may be lower than the value provided hereinabove by 1.5-3-fold.

[0222] In some embodiments, the system may include a buffer selected from phosphate buffer, carbonate / bicarbonate buffer, ammonia / ammonium, sulfide / bisulfide, organic buffers, such as acetate / acetic acid, propionate / propionic acid, lactate / lactic acid, or industrial buffers, such as borate, citrate, amines, etc. Each possibility is a separate embodiment. The buffer may originate from the wastewater or from an external source.

[0223] In some embodiments, the chemical consumption required for a system that utilizes the produced catholyte solution may be between 0.2-1.5 molOH / molN, 1.5-2.5 molOH / molN, or 0.8-3.5 molOH / molN. Each possibility is a separate embodiment.

[0224] According to some embodiments, wastewater including a buffer may allow a synergy between the system configuration, which facilitates the utilization of the produced catholyte solution, and the buffered solution. Accordingly, the chemical consumption value may be lower than the theoretical value for undivided cell, i.e., can be lower than 1 molOH / molN.

[0225] In some embodiments, the buffer manages the "acid debt" at the electrode surface, while simultaneously the flux resulting from the system configuration, such as in systems 100, 200, 500 or 600, supplies hydroxide ions from the catholyte, i.e., produced catholyte solution.

[0226] In some embodiments, in a system including a buffer such as bicarbonate, some CO2 generated from the bicarbonate-proton reaction may be partially re-absorbed or trapped within the liquid phase as it is forced through the diaphragm, creating an internal "buffering loop" that further suppresses the need for external basic chemical salt, such as NaOH.

[0227] According to some embodiments, localized alkalinity recovery through the porous diaphragm (such as in systems 500 or 600) may minimize or eliminate the requirement for additional external caustic addition to maintain neutrality in the anolyte compartment.

[0228] According to some embodiments, the transfer of produced catholyte solution through the porous diaphragm (e.g., system 600) may inherently treat more wastewater volume per time unit, as compared to the transfer of the produced catholyte solution to the anolyte compartment and / or to the wastewater tank by bypassing the membrane between the compartments (e.g.,systems 100 or 200). The liquid volume of the wastewater tank may be forced to go through the compartments with minimum or no liquid volume compensation (e.g., via make-up fluid) to the catholyte compartment. By forcing the wastewater to flow through the diaphragm, the system may utilize the entire volume of both compartments as a unified reaction zone.

[0229] According to some embodiments, the system, including the transfer of produced catholyte solution through the porous diaphragm (e.g., system 600), may increase the collision frequency between reactants and the electrode surface, which, combined with the stabilized pH, accelerates the ammonia oxidation rate and allows for higher volumetric loading.

[0230] According to some embodiments, the wastewater includes one or more contaminants. According to some embodiments, the one or more contaminants includes, but not limited to, ammonium.

[0231] According to some embodiments, the one or more contaminants may include, but not limited to, inorganic compounds of ammoniacal nitrogen (such as NH3 and NH4+), sulfides, or metal salts. Each possibility is a separate embodiment.

[0232] According to some embodiments, the one or more contaminants may include organic compounds of ammoniacal nitrogen, such as, but not limited to, urea, alkylamine (e.g., ethylamine), amino acid compound, amide compound, or guanidine. Each possibility is a separate embodiment.

[0233] According to some embodiments, the one or more contaminants may include organic molecules selected from, but not limited to, amino acids, lipids, carbohydrates, or proteins. Each possibility is a separate embodiment.

[0234] According to some embodiments, the one or more contaminants may include biological species, selected from, but not limited to, cells, bacteria, viruses, or fungi. Each possibility is a separate embodiment.

[0235] According to some embodiments, the one or more contaminants may include industrial chemical entities selected from, but not limited to, pharmaceuticals, dyes, polymers, or halogenated polymers and / or compounds. Each possibility is a separate embodiment.

[0236] According to some embodiments, the system is configured to transfer at least a portion of the produced catholyte solution, when the pH at the anolyte solution and / or at the wastewatertank drops below the pH value of 4 and maintain the solution pH at a pH of over about 4, such as, for example, in the range of about pH 4-9.

[0237] According to some embodiments, the bypass pump, such as in system 100 or 200, is configured to transfer at least a portion of the produced catholyte solution, when the pH at the anolyte solution and / or at the wastewater tank drops below the pH value of 6 and maintain the solution pH at a pH of over about 6, such as, for example, in the range of about pH 6-8.

[0238] According to some embodiments, the bypass pump is configured to transfer at least a portion of the produced catholyte solution towards the anolyte compartment, when the pH of the produced catholyte solution is about 12-14, for example, about 12-14, or about 12.5-13.5. Each possibility is a separate embodiment.

[0239] According to some embodiments, the bypass pump is configured to transfer at least a portion of the produced catholyte solution toward the anolyte compartment, when the pH at the anolyte compartment and / or at the wastewater tank is less than about 6, for example, pH 6 to 4, pH 5 to 3, pH 4 to 2, or pH 3 to 0. Each possibility is a separate embodiment.

[0240] According to some embodiments, the bypass pump is configured to transfer at least a portion of the produced catholyte solution toward the anolyte compartment, to match the amount of hydroxide ions transferred from the produced catholyte solution with the amount of proton ions at the anolyte compartment by at least about 80%, for example, to match the amount by about 80-90%, to match the amount by about 85-95%, or to match the amount by about 90-100%.

[0241] According to some embodiments, the electrochemical wastewater treatment system further includes a catholyte tank fluidly connected to the catholyte compartment. In some embodiments, the catholyte tank may be fluidly connected to a wastewater tank, which is fluidly connected to the anolyte compartment. In some embodiments, the catholyte tank may be fluidly connected directly to the anolyte compartment.

[0242] According to some embodiments, the electrochemical wastewater treatment system includes a wastewater tank fluidly connected to the anolyte compartment.

[0243] According to some embodiments, the catholyte tank or catholyte compartment is further fluidly connected to a make-up fluid source. In some embodiments, the catholyte tank isconfigured to receive the make-up fluid from the make-up fluid source. In some embodiments, the make-up fluid may include wastewater. In some embodiments, the make-up fluid may include treated water. In some embodiments, the make-up fluid may include water. In some embodiments, the make-up fluid may include water or treated water with salt. According to some embodiments, is water that has been treated to reduce the level of certain ions and / or organic entities. In some embodiments, the make-up fluid may include a salt solution. In some embodiments, the make-up fluid may include a brine solution. In some embodiments, the make-up fluid may be characterized by a high conductivity in the range of 10-40 mS / cm, for example, about 10-30 mS / cm, about 20-40 mS / cm, about 15-35 mS / cm. Each possibility is a separate embodiment. In some embodiments, the make-up fluid is configured to compensate for at least part of the volume lost at the catholyte compartment during the process.

[0244] In some embodiments, the make-up fluid source may include water, treated water, salt, wastewater, or any combination thereof. Each possibility is a separate embodiment. In some embodiments, the make-up fluid source includes wastewater. Utilization of the wastewater as a make-up fluid enables compensating for fluid loss at the catholyte compartment during the herein disclosed process. Advantageously, in some embodiments, utilizing the wastewater for make-up may minimize the use of water, treated water, or externally added salt in the make-up fluid. In some embodiments, utilizing the wastewater as a make-up fluid is an additional path to (indirectly) introduce the wastewater to the anolyte compartment (for treatment). According to some embodiments, the wastewater make-up fluid is indirectly introduced to the anolyte compartment through the catholyte compartment via the bypass pump, as a produced catholyte solution.

[0245] According to some embodiments, the bypass pump facilitates bypassing the ion exchange membrane. The bypass pump, in accordance with some embodiments, does not move the fluid through the ion exchange membrane.

[0246] According to some embodiments, the bypass pump is fluidly associated with the catholyte tank and at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump towards the anolyte compartment through the catholyte tank.

[0247] According to some further embodiments, the bypass pump is fluidly associated with the catholyte compartment and at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump towards the anolyte compartment. In someembodiments, the at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump directly to the anolyte compartment.

[0248] According to some embodiments, the at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump directly from the catholyte compartment and / or through the catholyte tank.

[0249] According to some embodiments, the anolyte compartment is configured to receive wastewater and / or the produced catholyte solution.

[0250] According to some embodiments, the anolyte compartment is further configured to output treated wastewater. According to some embodiments, the anolyte compartment is configured to output treated wastewater upon / during system operation. According to some embodiments, the anolyte compartment is configured to output treated wastewater upon / during system operation and / or oxidation reaction. According to some embodiments, the anolyte compartment is further configured to output treated wastewater upon / during system operation and / or oxidation of ammonia (ammonium ions).

[0251] According to some embodiments, at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump to the wastewater tank.

[0252] Yet according to some further embodiments, at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump directly to the anolyte compartment.

[0253] According to some embodiments, at least a portion of the produced catholyte solution is configured to be transferred by the bypass pump to the wastewater tank and / or to the anolyte compartment.

[0254] According to some embodiments, at least a portion of the produced catholyte solution is configured to be transferred to the catholyte tank (e.g., by a conduit assembly and / or the catholyte pump), and transferred therefrom, by the bypass pump, to the wastewater tank and / or the anolyte compartment.

[0255] According to some embodiments, the wastewater tank is further fluidly connected to a wastewater source.According to some embodiments, the wastewater may be or may include such fluids as, but not limited to: biological fluid, grey water, black water, industrial waste stream, cell culture medium, chemical industry-related medium, domestic wastewater, agriculture runoff, industrial wastewater, municipal wastewater, cooling water, leachate from landfills, sewer water, and the like, or any combinations thereof. Each possibility is a separate embodiment.

[0256] According to some embodiments, the system further includes one or more pH sensors configured to measure pH levels. In some embodiments, the one or more pH sensors may be positioned at, or associated with, but not limited to, catholyte compartment, anolyte compartment, catholyte tank, wastewater tank, wastewater source, make-up fluid source, and any combination thereof. Each possibility is a separate embodiment.

[0257] According to some embodiments, at least one of the one or more pH sensors is configured to measure pH level at the catholyte compartment and / or at the catholyte tank.

[0258] According to some embodiments, at least one of the one or more pH sensors is configured to measure pH level at the anolyte compartment and / or at the wastewater tank.

[0259] According to some embodiments, the one or more pH sensors are positioned in, and / or configured to measure pH level, at one or more of the following: the catholyte compartment, the catholyte tank, the anolyte compartment, and the wastewater tank. Each possibility is a separate embodiment.

[0260] According to some embodiments, at least one of the one or more pH sensors is functionally associated with the bypass pump and thus is configured to regulate the transfer of at least a portion of the produced catholyte solution, based on the measured pH level. In some embodiments, the bypass pump is configured to regulate the transfer of at least a portion of the produced catholyte solution, based on the measured pH level by the sensor. In some embodiments, the regulation is done automatically. In some other embodiments, the regulation is performed manually. In some embodiments, the regulation is performed continuously. In some other embodiments, the regulation is performed intermittently.

[0261] According to some embodiments, the system may further include a catholyte pump configured to transfer fluid from a catholyte tank to the catholyte compartment. According to some embodiments, the system further includes a catholyte pump configured to transfer fluid from the catholyte compartment to the catholyte tank.According to some embodiments, the system further includes a wastewater pump configured to transfer fluid from a wastewater tank to the anolyte compartment.

[0262] According to some embodiments, the system further includes one or more valves configured to control / regulate fluid passage in the system. According to some embodiments, the one or more valves may be selected from, but not limited to, solenoid valve, pressure valve, diaphragm valve, proportional valve, and any combinations thereof. Each possibility is a separate embodiment.

[0263] According to some embodiments, the system further includes a power source, a power supply, a central control unit, a communication unit, a user interface, or any combination thereof. Each possibility is a separate embodiment.

[0264] According to some embodiments, the system further includes a power supply to apply an electric field to the electrochemical cell. In some embodiments, regulation of the electric field may be further associated with the regulation of the transfer of the produced catholyte solution. In some embodiments, the regulation of the electric field is associated with pH sensing. In some embodiments, regulation of the electric field may be further associated with the introduction flow of the wastewater from the wastewater source to the wastewater tank, and / or associated with the outputting flow of the treated water from the anolyte compartment to any target location. In some embodiments, the target location may include a line, position, or vessel outside the herein disclosed system that may be opened or closed. Each possibility is a separate embodiment.

[0265] In some embodiments, the power supply may utilize the hydrogen produced by the system disclosed herein.

[0266] According to some embodiments, the bypass pump is selected from, but is not limited to, booster pump, centrifugal pump, piston pump, diaphragm pump, jet pump, reciprocating pump, rotary compressor, peristaltic pump, positive displacement pump, gear pump, lobe pump, screw pump, vane pump, progressive cavity pump, plunger pump, rotary lobe pump, magnetic drive pump, submersible pump, axial flow pump, radial flow pump, multistage pump, hydraulic pump, rotary screw pump, compressor pump, in-line pump, and any combination thereof. Each possibility is a separate embodiment.

[0267] According to some embodiments, the bypass pump is a rotary compressor pump.According to some embodiments, the bypass pump is a positive displacement pump.

[0268] According to some embodiments, the wastewater pump and / or the catholyte pump are each independently selected from, but are not limited to, booster pump, centrifugal pump, piston pump, diaphragm pump, jet pump, reciprocating pump, rotary compressor, peristaltic pump, positive displacement pump, gear pump, lobe pump, screw pump, vane pump, progressive cavity pump, plunger pump, rotary lobe pump, magnetic drive pump, submersible pump, axial flow pump, radial flow pump, multistage pump, hydraulic pump, rotary screw pump, compressor pump, in-line pump, and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the wastewater and / or the catholyte pumps are centrifugal pumps.

[0269] The system may further include a power source, a central control unit, a communication unit, a user interface, or any combination thereof. Each possibility is a separate embodiment.

[0270] According to some embodiments, the system includes a plurality of electrochemical cells, wherein at least a portion of catholyte solution produced in the plurality of catholyte compartments is configured to be transferred to a catholyte tank. In some embodiments, the at least a portion of the catholyte solution produced at the plurality of catholyte compartments is transferred (from the catholyte tank and / or directly from the plurality of catholyte compartments) to a wastewater tank and / or an anolyte compartment, when the measured pH levels at the catholyte tank and / or at the plurality of catholyte compartment is above a predetermined threshold. In some embodiments, the at least a portion of the catholyte solution produced at the plurality of catholyte compartments is transferred (from the catholyte tank and / or directly from the plurality of catholyte compartments) to a wastewater tank and / or an anolyte compartment, when the measured pH levels at the wastewater tank and / or the anolyte compartment are below a predetermined threshold. In some embodiments, the predetermined threshold for the produced catholyte solution (in the catholyte tank / compartment) may be above pH 12, above pH 13, or above pH 14. Each possibility is a separate embodiment. In some embodiments, the transfer of the catholyte solution produced in the plurality of catholyte compartments (optionally through the catholyte tank) to a wastewater tank and / or an anolyte compartment is performed when pH level determined at a wastewater tank and / or an anolyte compartment is less than about pH 6, less than about pH 5.5, less than about pH 5, less than about pH 4.5, less than about pH 4, less than about pH 3.5, less than about pH 3, less than about pH 2.5, less than about pH 2, less than about pH 1.5, or less than about pH 1. Each possibilityis a separate embodiment. In some embodiments, the pH threshold at the wastewater tank and / or an anolyte compartment (for the transfer of the produced catholyte solution to a wastewater tank and / or an anolyte compartment) is between about pH 6-4, between about pH 6-3, between about pH 5-2, between about pH 5-1, between about pH 4-1, between about pH 6-1, or between about pH 2-1, or between about pH 5-1 and below. Each possibility is a separate embodiment.

[0271] According to some embodiments, the system further includes a plurality of electrochemical cells, wherein, catholyte solution produced in the plurality of catholyte compartments is configured to be transferred towards an anolyte compartment.

[0272] According to some embodiments, at least a portion of the produced catholyte solution from the plurality of catholyte compartments may be transferred (by the bypass pump) to a wastewater tank and / or to an anolyte compartment when measured pH level at the plurality of catholyte compartments is above a predetermined threshold and / or when measured pH level at the wastewater tank and / or at the anolyte compartment is below a predetermined threshold.

[0273] According to some embodiments, the system is for use in wastewater treatment. In some embodiments, the system is for use in reducing an amount of one or more contaminants in wastewater. In some embodiments, the system is for use in reducing an amount of ammonium in wastewater. According to some embodiments, the system is for use in producing hydrogen gas and / or oxygen gas.

[0274] There is provided, in accordance with some embodiments, a method of treating wastewater. Reference is made to FIG. 7, which schematically illustrates a flowchart of a method for treating wastewater and / or producing hydrogen, while regulating the acidity level in the anolyte compartment, according to some embodiments. The treatment method may include obtaining or providing the herein disclosed system. In some embodiments, the system includes a cation exchange membrane. In some embodiments, the system includes a porous diaphragm.

[0275] In some embodiments, the system includes a combination of a cation exchange membrane and a (second) catholyte outlet, which allows the flow of the produced catholyte solution around the membrane via the conduit assembly, towards the anolyte compartment.In some embodiments, the system includes a porous diaphragm and a catholyte outlet having a (first) valve that is at least partially closed to liquids. This combination creates a hydraulic head that pressurizes the produced catholyte solution through the porous diaphragm to the anolyte compartment.

[0276] In step 720, the wastewater is allowed to reach the electrochemical cell. The wastewater can be flown to the electrochemical cell via a first conduit assembly from a wastewater tank. For example, the wastewater can be transferred by using a pump or via gravitation force means. The wastewater can be introduced into the electrochemical cell via the anolyte inlet, the catholyte inlet, or through both inlets. In some embodiments, step 730 includes applying an electric field using a power supply to create an electrochemical reaction on the wastewater, i.e., to treat the wastewater, such that ammonia is converted to nitrogen gas in the anolyte compartment, and / or hydrogen gas is produced at the catholyte compartment. In step 740 or 750, which can concurrently occur during the cell operation, the produced catholyte solution is transferred to the anolyte compartment to increase the pH thereof. In some embodiments, step 740 includes transferring the produced catholyte solution via a catholyte outlet, optionally having a (second) valve, through a (second) conduit assembly to the anolyte compartment and / or the wastewater tank. The transfer may utilize the gravity of a pump, e.g., a bypass pump. In this route, the transfer may bypass around the membrane, such as a cation exchange membrane or porous diaphragm, to reach the anolyte compartment. In some embodiments, route 750 includes transferring the produced catholyte solution from the catholyte compartment by at least partially closing a (first) catholyte valve outlet. The closure creates hydraulic head, i.e., pressure on the produced catholyte solution to pass through the membrane, e.g., through a porous diaphragm, to the anolyte compartment. In some embodiments, the closure of the catholyte outlet valve and / or the membrane type is suitable to create a differential pressure on the membrane that is between 180 mbar and 220 mbar, to avoid membrane breakout and allow liquid transfer while minimizing gas transfer through the membrane, i.e., to maintain the pressure below the bubble point of the membrane.

[0277] According to some embodiments, the method includes step 740. According to some embodiments, the method includes step 750. According to some embodiments, the method includes steps 740 and 750.

[0278] Accordingly, the method allows for keeping the pH level in the anolyte compartment above pH 4, while producing treated wastewater in the anolyte compartment and hydrogen gasin the catholyte compartment. In step 760, the treated water may be collected during and / or after the system operation. The collection of the gas may be from the anolyte compartment outlet and / or from the wastewater tank. In some embodiments, the produced hydrogen gas may be collected from the catholyte outlet valve. In some embodiments, the produced hydrogen gas may be collected from the second conduit assembly.

[0279] There is provided, in accordance with some embodiments, a method for treating wastewater, the method includes:

[0280] allowing wastewater to reach the electrochemical cell of the herein disclosed system; applying an electric field between the catholyte and anolyte compartments, to oxidize contaminants in the wastewater and produce a catholyte solution in the catholyte compartment; and

[0281] transferring at least a portion of the produced catholyte solution towards the anolyte compartment,

[0282] such that the pH level at the anolyte compartment is maintained at a value of at least about 4.

[0283] There is provided, in accordance with some embodiments, a method for treating wastewater, the method includes:

[0284] allowing wastewater to reach the electrochemical cell (e.g., the anolyte compartment) of the herein disclosed system;

[0285] applying an electric field between the catholyte and anolyte compartments, to oxidize contaminants in the wastewater and produce a catholyte solution in the catholyte compartment; and

[0286] transferring, via the second conduit assembly around (while bypassing) the membrane, at least a portion of the produced catholyte solution, towards the anolyte compartment, such that the pH level at the anolyte compartment is maintained at a value of at least about 4.

[0287] There is provided, in accordance with some embodiments, a method for treating wastewater, the method includes:allowing wastewater to reach the electrochemical cell of the herein disclosed system, e.g., via a first conduit assembly;

[0288] applying an electric field between the catholyte and anolyte compartments, to oxidize contaminants in the wastewater and produce a catholyte solution in the catholyte compartment; and

[0289] transferring, via a second conduit assembly around (while bypassing) the membrane, at least a portion of the produced catholyte solution, towards the anolyte compartment, such that the external alkaline agent required for neutralizing the pH at the anolyte compartment is maintained at a value below 2 molOH / molN.

[0290] In some embodiments, the method includes using a porous diaphragm membrane. In some embodiments, the external alkaline agent required to neutralize the produced anolyte solution may be between 1-2 molOH / molN, between 1.2- 1.5 molOH / molN, or between 1-3.5 molOH / molN. Each possibility is a separate embodiment.

[0291] In some embodiments, the method includes using a cation exchange membrane. In some embodiments, the external alkaline agent required may be less than 1.2-1.5molOH / molN.

[0292] In some embodiments, the produced catholyte solution is flown through the second catholyte outlet through the second conduit assembly such that the produced catholyte solution is transferred around the membrane, which is a cation exchange or a diaphragm, to the anolyte compartment.

[0293] There is provided, in accordance with some embodiments, a method for treating wastewater, the method includes:

[0294] allowing wastewater to reach the electrochemical cell of the herein disclosed system, e.g., via a first conduit assembly;

[0295] applying an electric field between the catholyte and anolyte compartments, to oxidize contaminants in the wastewater and produce a catholyte solution in the catholyte compartment; and

[0296] transferring at least a portion of the produced catholyte solution towards the anolyte compartment by selectively permitting gas output from the first valve of the catholyte outlet, to pressurize the produced catholyte solution through the membrane,wherein the pH at the anolyte is maintained above pH 4.

[0297] In some embodiments, the membrane is a porous diaphragm. Accordingly, in some embodiments, in this method, the external alkaline agent required for neutralizing the pH at the anolyte compartment is maintained at a value below 1.5 molOH / molN. For example, the external alkaline agent demand to neutralize the produced anolyte solution may be between 0.3-1.5 molOH / molN, between 0.4-1.2 molOH / molN, or between 0.4-1 molOH / molN. Each possibility is a separate embodiment.

[0298] In some embodiments, the first valve of the catholyte compartment selectively permits a gas output and prevents or reduces liquid effluent, such that the differential pressure on the membrane is set to be between 150-250 mbar, for example, 150-200 mbar, 180-200 mbar, or 180-220 mbar. Each possibility is a separate embodiment.

[0299] In some embodiments, the first valve of the catholyte outlet is closed or partially closed for a liquid flow such that the produced catholyte solution is pushed back through the membrane, which is a diaphragm membrane, to the anolyte compartment.

[0300] There is provided, in accordance with some embodiments, a method for treating wastewater, the method includes:

[0301] obtaining or providing the electrochemical system disclosed herein;

[0302] allowing wastewater to reach the electrochemical cell;

[0303] applying an electric field between the catholyte and anolyte compartments, to oxidize contaminants in the wastewater and produce a catholyte solution in the catholyte compartment; and

[0304] transferring, using the bypass pump, at least a portion of the produced catholyte solution, towards the anolyte compartment,

[0305] such that the pH level at the anolyte compartment is maintained at a value of at least about 5.

[0306] In some embodiments, the method may include collecting hydrogen gas from the catholyte compartment outlet, from the second conduit assembly, or from the catholyte tank. Each possibility is a separate embodiment.According to some embodiments, the ammonia contaminant is converted to nitrogen gas during the treatment.

[0307] In some embodiments, the oxidation of the contaminants is performed by directly electrooxidizing the one or more contaminants, during operation of the electrochemical system. In some embodiments, the oxidation of the contaminants is done (indirectly) by a reaction of the one or more contaminants, such as ammonium, with oxidative intermediate products that are formed via electrooxidation, during operation of the electrochemical system.

[0308] According to some embodiments, the herein disclosed method maintains the pH level at the anolyte compartment at a value of at least about pH 4, for example, at least about pH 5, at least about pH 6, at least about pH 7, at least about pH 8, or at least about pH 9. Each possibility is a separate embodiment. According to some embodiments, the herein disclosed method maintains the pH level at the anolyte compartment at a value in the range of about pH 4-12, for example, about pH 6-11, about pH 6-10, about pH 6-9, or about pH 6-8. Each possibility is a separate embodiment. According to some embodiments, the herein disclosed method maintains the pH level at the anolyte compartment at a value in the range of about pH 6-9.

[0309] According to some embodiments, the method may further include flowing / adding an external alkaline agent to the anolyte compartment. Non-limiting examples of the alkaline agent may include, in some embodiments, sodium hydroxide, potassium hydroxide, calcium hydroxide, or magnesium hydroxide. Each possibility is a separate embodiment. According to some embodiments, the method may further include adding an alkaline agent to the anolyte compartment to complement the transfer of the produced catholyte solution toward the anolyte compartment. In some embodiments, the externally added alkaline agent may complement about 0-50% of the hydroxide ions required to maintain the pH at the anolyte compartment in the range of at least about 6-8. For example, the externally added alkaline agent complements about 0.5-40%, about 0.5-30%, about 0.5-20%, about 0.5-10%, about 0.5-5%, or about 0.5-3% of the required hydroxide ions. Each possibility is a separate embodiment. In some embodiments, the method does not include adding an external alkaline agent to the anolyte compartment. In some embodiments, produced catholyte solution may be the sole source of alkalinity used to increase the anolyte compartment's pH level. The electrochemical wastewater treatment system provided herein may be devoid of an external alkaline additive.According to some embodiments, the method further includes sensing, using a pH sensor, the pH level at one or more of: the catholyte compartment, a catholyte tank, the anolyte compartment, a wastewater tank, or any combination thereof. Each possibility is a separate embodiment.

[0310] Reference is now made to FIG. 8, which schematically illustrates a flowchart of a method for treating wastewater and / or producing hydrogen, while regulating acidity level in the anolyte compartment, according to some embodiments. As shown in FIG. 8, treatment method 400 includes step 410 obtaining the electrochemical system disclosed herein. According to some embodiments, in step 420, the wastewater is allowed to reach the anolyte compartment. In some embodiments, the wastewater reaches the anolyte compartment via a wastewater pump, connected vessels, gravitation, valve(s), through one or more wastewater tanks, filter(s), channel(s), or any combination thereof. In step 430, in accordance with some embodiments, an electric field is applied between the cathode and anode of the catholyte and anolyte compartments, respectively. In an optional step 440, sensing, using one or more pH sensors, is performed to determine the pH level, in accordance with some embodiments. The pH may be determined at the anolyte compartment, catholyte compartment, wastewater tank, catholyte tank, system’s entry, system’s exit, or any combination thereof. According to some further embodiments, the sensing can be done in any location in the conduit assembly of the electrochemical wastewater treatment system. According to some embodiments, in optional step 450, the pH level at any of the abovementioned locations is evaluated and compared to a pre-determined threshold. In some embodiments, based on the evaluation, it can be assessed that the level of alkalinity of the produced catholyte solution at the catholyte compartment / tank is high enough to be transferred toward the anolyte compartment (e.g., the pH is at least above pH 12). In some embodiments, based on the evaluation, it can be assessed that the level of acidity at the anolyte compartment and / or wastewater tank is high enough and thus requires the transfer of the produced catholyte solution thereto. The required transfer rate and / or timing of the produced catholyte solution flow / transfer, according to some embodiments, may also be assessed in this step. According to some embodiments, at least a portion of the produced catholyte solution is transferred in step 460 towards the anolyte compartment, threshold according to the measurements and evaluation of the pH as mentioned herein. In some embodiments, as a result of the transfer of the produced catholyte solution, the acidity level at the anolyte compartment is regulated. In some embodiments, in step 470, the pH level at the anolyte compartment is thereby maintained at a range of about 5-8. In some embodiments, inan optional step 480 a make-up fluid from a make-up fluid source is introduced to the catholyte compartment, to compensate fluid loss during the disclosed process. In some embodiments, the make-up fluid may include water, wastewater, and / or salt. In some embodiments, the wastewater may originate from the wastewater tank or another wastewater source.

[0311] According to some embodiments, the pH regulation as disclosed herein enhances the wastewater treatment efficiency. In some embodiments, the pH regulation as disclosed herein facilitates an oxidation / removal / transformation of ammonium. According to some embodiments, the pH level is measured in real time. According to some embodiments, the regulation of acidity is performed in real time.

[0312] According to some embodiments, the method may further include adding make-up fluid to the catholyte tank. In some embodiments, the make-up fluid originates from a make-up fluid source. In some embodiments, the wastewater of the make-up fluid may originate from the wastewater tank and / or another wastewater source. The fluid compensates for a reduction of fluid volume in the catholyte tank and / or the catholyte compartment. In some embodiments, the added make-up fluid is a catholyte make-up for the catholyte tank. In some embodiments, the make-up fluid may include, but not limited to, wastewater, treated water, untreated water, and / or added salt. In some embodiments, the added salt may include, but not limited to, sodium chloride, potassium chloride, sodium sulphate, sodium bicarbonate, sodium carbonate, or any combination thereof. Each possibility is a separate embodiment.

[0313] According to some embodiments, the transferring of at least a portion of the produced catholyte solution towards the anolyte compartment is performed automatically. In some embodiments, the timing and / or amount (i.e., rate) of transferring the produced catholyte solution is determined based on the measured pH. In some further embodiments, the amount and / or timing of transferring the produced catholyte solution is determined based on the pH sensing and based on a pre-programmed flow and / or pH plan. In some further embodiments, the time and / or amount of transferring the produced catholyte solution is determined based on the pH, the intensity of the applied electric field, and / or the pre-programmed pH / flow plan.

[0314] In some other embodiments, the transferring of at least a portion of the produced catholyte solution towards the anolyte compartment is performed manually.

[0315] According to some embodiments, the method may be used in the treatment of wastewater, including ammonia. According to some embodiments, the method may reduce theammonia level in the wastewater by about 10-95%, for example, about 20-95%, about 30-95%, about 40-95%, about 50-95%, about 60-95%, about 70-95%, about 80-95% or above about 95-99%. Each possibility is a separate embodiment. According to some embodiments, the herein reduction of ammonia level in the outputted treated wastewater is relative to the ammonia level in the wastewater entering the herein disclosed system. A specific energy consumption, which measures the energy required to remove a specific amount of the contaminant, ranges from about 17-40 kilowatt-hours per kilogram of nitrogen removed, for example, about 17-35, about 17-30, about 19-30, or about 19 to 25 kilowatt-hours per kilogram of nitrogen removed. In some embodiments, the nitrogen may be removed in the form of nitrogen gas and may originate in ammonia.

[0316] According to some embodiments, the method is performed continuously. In some embodiments, the transferring of the produced catholyte solution is continuous.

[0317] According to some embodiments, the method is performed intermittently. In some embodiments, the transferring of the produced catholyte solution is intermittent.

[0318] According to some embodiments, the method may be performed automatically, and / or alternatively, manually.

[0319] According to some embodiments, the flow rate of transferring the produced catholyte solution is about 0.5-20 liter / hour, for example, about 0.5-2 liter / hour, about 2-5 liter / hour, about 5-10 liter / hour, about 10-15 liter / hour, or about 15-20 liter / hour. Each possibility is a separate embodiment

[0320] According to some embodiments, hydrogen gas is produced at the catholyte compartment during operation of the system.

[0321] According to some embodiments, nitrogen gas is produced at the anolyte compartment during operation of the system. According to some embodiments, nitrogen gas is produced at the anolyte compartment during operation of the system as a result of ammonia oxidation.

[0322] The following examples are presented in order to more fully illustrate some embodiments of the invention. They should, in no way be construed, however, as limiting the broad scope of the invention. One skilled in the art can readily devise many variations andmodifications of the principles disclosed herein without departing from the scope of the invention.

[0323] EXAMPLES

[0324] Example 1 - Measuring ammonia removal and pH level in a system comprising anolyte and catholyte compartments divided by a porous PVDF diaphragm (reference system)

[0325] Operational Parameters:

[0326] Electrolyte: a synthetic wastewater solution was made with 300mgN / L (0.021 M), salts, and with the addition of equimolar bicarbonate (HCO3-) as a buffering agent (1.3 gr / L). The buffer may mimic the buffer in a wastewater source. The starting pH of the solution is pH 8.

[0327] Hydrodynamic Flux: 40 mL / min

[0328] Galvanostatic Control: 7Amp on a 100cm2active area cell (70 mA / cm2)

[0329] Phase Separator: PVDF porous diaphragm having a pore size of 0.2 pm and 120 pm thickness.

[0330] The wastewater was fed separately into an anolyte compartment and a corresponding catholyte compartment. The pH was continuously monitored by pH transients in both vessels. After 30 minutes, a post-experimental titration of the accumulated anolyte solution was performed using standardized NaOH to a terminal pH of 7.0. The caustic consumption was then normalized against the total mass of ammonia removed (molOH- / molN).

[0331] A comparative system lacking the buffer was evaluated in the same manner as described for that with the buffer.

[0332] FIG. 9 illustrates the dynamic pH profiles of the anolyte and catholyte compartments alongside the corresponding electrochemical performance for ammonia nitrogen removal from the anolyte compartment during the buffered reference experiment (without utilizing the produced catholyte solution). The catholyte solution (upper x trace) reached to pH level above 12, the anolyte solution (lower x trace) dropped to a pH value below 2. The ammonia level (solid trace) was reduced to less than 50 mgN / L. Accordingly, the chemical consumption found based on back titration of the produced anolyte solution was measured to be 2.6 molOH / molN.Example 2 -Measuring ammonia removal and pH level in a system comprising anolyte and catholyte compartments divided by a porous PVDF diaphragm - transferring the produced catholyte solution by bypassing the diaphragm

[0333] Operational Parameters:

[0334] Electrolyte: a synthetic wastewater solution was made with 300mgN / L (0.021 M), salts, and with the addition of equimolar bicarbonate (HCO3-) as a buffering agent (1.3 gr / L). The buffer may mimic the buffer in a wastewater source. The starting pH of the solution was pH 8.

[0335] Hydrodynamic Flux: 40 mL / min

[0336] Galvanostatic Control: 7Amp on a 100cm2active area cell (70 mA / cm2)

[0337] Phase Separator: PVDF porous diaphragm having a pore size of 0.2 pm and 120 pm thickness.

[0338] In system 500, the wastewater was fed separately into an anolyte compartment and a corresponding catholyte compartment. The catholyte effluent line 514 was configured to discharge 517 into the primary influent (Bulk) reservoir 504.

[0339] The anolyte effluent 520 was collected independently. The pH fluctuations within the bulk wastewater reservoir 504 and at the anolyte effluent 520 were recorded to characterize the buffering kinetics. The residual chemical demand was quantified via titration of the accumulated anolyte solution to pH 7, similarly to what was done in Example 1, using NaOH solution.

[0340] A comparative system lacking the buffer was evaluated in the same manner as described for that with the buffer.

[0341] FIG. 10 illustrates the dynamic pH profiles of the anolyte compartment and the wastewater tank alongside the corresponding electrochemical performance for ammonia nitrogen removal during the buffered experiment utilizing the produced catholyte solution bypassing the membrane, i.e., output through 514 from catholyte compartment 502. The catholyte solution is recycled in this system. The wastewater tank reservoir (upper x trace in the figure) reached to pH level above 12 (from pH 8), the anolyte solution (lower x trace in the figure) dropped to a pH value below 2, and the ammonia level (solid trace) was reduced to less than 50 mgN / L. Ammonia removal was measured at the exit from the anolyte compartment.Accordingly, the chemical consumption found based on back titration of the produced anolyte solution was measured to be 1.3 molOH / molN, which is half of what was measured in the reference system in Example 1. The results demonstrate that the system generates sufficient internal alkalinity to compensate for the acid debt incurred during electrochemical ammonia removal. Consequently, the reduction in external chemical demand serves as a primary metric of efficiency, as the anolyte pH remains an indicator of intensity rather than total capacity.

[0342] Example 3 - Measuring ammonia removal and pH level in a system comprising anolyte and catholyte compartments divided by a porous PVDF diaphragm - regulating pH by transferring the produced catholyte solution through the membrane

[0343] Operational Parameters:

[0344] Electrolyte: a synthetic wastewater solution was made with 300mgN / L (0.021 M), salts, and with the addition of equimolar bicarbonate (HCO3-) as a buffering agent (1.3 gr / L). The buffer may mimic the buffer in a wastewater source. The starting pH of the solution was pH 8.

[0345] Hydrodynamic Flux: 40 mL / min

[0346] Galvanostatic Control: 7Amp on a 100cm2active area cell (70 mA / cm2)

[0347] Phase Separator: PVDF porous diaphragm having a pore size of 0.2 pm and 120 pm thickness.

[0348] As shown in system 600, in this mode, the system was transitioned to a pressure-driven operational mode where the diaphragm 603 served as the primary conduit for both liquid and alkalinity transport.

[0349] The catholyte effluent line 612 was adjusted to establish a controlled hydraulic head using valve 606. This pressure elevation created a trans-membrane pressure (TMP) sufficient to overcome the diaphragm's capillary resistance, thereby forcing the produced (alkaline) catholyte solution through the pores from the catholyte compartment 602 and into the anolyte compartment 601. The anolyte effluent was independently collected from 613. The pH fluctuations were recorded within the bulk reservoir 604 and at the anolyte outlet to characterize the buffering kinetics. The residual chemical demand for neutralizing the anolyte compartment was quantified via titration, similarly as was done in Examples 1 and 2.

[0350] A comparative system lacking the buffer was evaluated in the same manner as described for that with the buffer.FIG. 11 illustrates the dynamic pH profiles of the anolyte compartment and the wastewater tank alongside the corresponding electrochemical performance for ammonia nitrogen removal from the wastewater tank during the buffered experiment utilizing the produced catholyte solution passing through the membrane. The catholyte solution is pressurized through the membrane in this forced convective flux system. The wastewater tank reservoir (upper x trace in the figure) retained a pH level of about 8. The pH at the anolyte solution (lower x trace in the figure) dropped at the beginning (2 minutes) to a pH value below 2 and immediately after rose to a pH above pH 4 (~14 minutes). The ammonia level (solid trace) was reduced to about 50 mgN / L. Accordingly, the chemical consumption found based on back titration of the produced anolyte solution was measured to be 0.4 molOH / molN, which is 6.5-fold lower consumption, as compared to what was found in the reference system in Example 1, and 4-fold lower consumption, as compared to what was found for the membranebypassing system shown in Example 2.

[0351] Comparison between Examples 1-3, including a diaphragm:

[0352] The external alkaline agent (e.g., NaOH) required to maintain neutrality at the anolyte solution is a metric used to evaluate the system's capability to provide alkalinity to compensate for the acid debt from ammonia oxidation. Table 1 summarizes the molOH / molN ratios for the three examined operational modes described in Examples 1, 2, and 3. The results demonstrate a clear trend toward stoichiometric optimization as the system transitions from passive separation to active alkalinity management, with the Forced Convective Flux mode, e.g., system 600, achieving the lowest documented consumption of 0.4molOH / molN in buffered media. A buffered medium can be a good representative medium for the characteristic pH conditions in wastewater.

[0353] Table 1. Chemical demand for each experimental configuration, to neutralize the anolyte solution to pH 7

[0354] molOH / molN Configuration unbuffered buffered Reference (Example 1) 4.3 2.6 bypassing the diaphragm (Example 2) 3.2 1.3

[0355] through the diaphragm (Example 3) 1.2 0.4

[0356]

[0357] The significant reduction in chemical demand observed in the Forced Convective Flux mode of system 600, particularly the transition to 0.4 molOH / molN in buffered medium, represents a fundamental shift in the cell’s internal chemical equilibrium.

[0358] In the modes of the reference and membrane-bypassing systems, such as shown in Examples 1 and 2, the system is governed by the passive diffusion of ions across the diaphragm.

[0359] Additionally, in unbuffered systems, the high concentration of protons at the anolyte leads to significant back-migration into the catholyte, neutralizing the produced alkalinity before it can be effectively utilized.

[0360] The Forced Convective Flux system, such as shown in system 600 (Example 3), utilizes a hydraulic head to create a physical velocity vector directed from the catholyte compartment toward the anolyte compartment through the porous diaphragm membrane. This "sweep" effectively opposes the migration of proton ions (from the anolyte to the catholyte compartment), ensuring that the cathodic hydroxide ions are delivered directly into the anolyte compartment with high efficiency.

[0361] In the configuration of convective flux through a diaphragm, such as shown in Example 3, the alkaline chemical demand is 1.2 molOH / molN when the wastewater is not buffered. The value further drops to 0.4 molOH / molN when using a buffered wastewater. This suggests a synergy between the buffered wastewater and the forced convective flux system configuration, which together overperforms the theoretical performance of both the undivided and divided cells.

[0362] Provided that wastewater often inherently contains a buffer, this simulating system demonstrates efficient ammonia removal with good pH regulation and minimal or no chemical consumable requirements to maintain neutrality. The buffer manages the "acid debt" at the electrode surface, while the convective flux simultaneously supplies hydroxide ions from the catholyte compartment.

[0363] The performance of an electrolytic system for ammonia oxidation and hydrogen recovery may be influenced by the type of membrane. Choosing between an ion exchange membrane, such as Cation Exchange Membrane (CEM), and a porous diaphragm may dictate the efficiency of alkalinity recovery, the purity of the harvested gas, and the overall chemical demand of the process. A porous diaphragm may serve as a physical separator with microscopicpore structures that allow transport of liquid and ions while providing a barrier to gas bubbles. Gas separation in a diaphragm is achieved through the surface tension of the electrolyte filling its microscopic pores. As long as the pores remain smaller than the potential gas bubbles and are fully wetted, the liquid acts as a physical seal, reducing gas crossover up to a specific differential pressure. Unlike dense membranes (e.g., CEM), a diaphragm is permeable to hydraulic flow. This allows operators to maintain a higher pressure on the cathode side, forcing alkaline catholyte through the diaphragm into the anode. This convective flow physically sweeps cathodic hydroxide ions into the anolyte compartment oxidation zone to neutralize anodic protons in-situ, significantly lowering external chemical demand.

[0364] Example 4 - Ammonia removal process without pH correction at the anolyte compartment. The catholyte and anolyte compartments are separated by a cation exchange membrane (CEM), Nafion 212, 50 pm thickness

[0365] A volume of 4 liters of wastewater, including ammonia in a concentration of 47 mgN / L, was introduced into a wastewater tank and then circulated into the electrolytic cell for 2 hours. The electrochemical cell was operated in a constant current mode. The specific energy consumption was 44 kWh / kgN, i.e., per ammonia removed. The relatively high energy consumption can be attributed to the low pH, which may negatively impact the process efficiency. In this reference experiment, no alkaline solution was added to raise the pH of the anolyte compartment.

[0366] Example 5 - Ammonia removal in a continuous system including a pH correction using produced catholyte solution. The catholyte and anolyte compartments are separated by cation exchange membrane (CEM), Nafion 212, 50 pm thickness

[0367] The electrochemical system was operated continuously at a flow rate of about 1-3 liter / hour for 400 min to remove ammonia from simulated wastewater including ammonia at a concentration of 400 mgN / L. This purification was performed while maintaining the pH level in the anolyte compartment above pH 4 using a produced catholyte solution.

[0368] The low energy consumption, 21.8 kWh / kgN, as derived from this experiment, shows the advantage of using the produced catholyte solution to control the pH at the anolyte compartment.The experimental data confirm that using the produced catholyte solution in a recycling loop bypassing the ion exchange membrane is a highly effective strategy for minimizing the external chemical consumption of an electrolytic wastewater treatment system. By harvesting the hydroxide ions generated at the cathode and reintroducing them into the process flow, the system effectively utilizes "free" alkalinity that would otherwise be lost in a standard divided cell configuration.

[0369] The catholyte recycling transforms the cathode from a waste stream source into an active alkalinity generator. This creates a synergistic operational environment where the high-value recovery of hydrogen gas is balanced with the low-cost chemical performance typically reserved for undivided electrolytic cells.

[0370] CEM is a dense, non-porous polymer membrane fixed with negatively charged groups (e.g., sulfonated ionomers) that selectively permit cation transport while minimizing anions. By lowering the transport of hydroxide ions, the CEM ensures that most of the alkalinity generated at the cathode is concentrated in the catholyte compartment. This allows for highly efficient harvesting and theoretically brings external chemical demand down to the stoichiometric minimum.

[0371] Further, by being relatively dense, the CEM provides an effective barrier against gas crossover, facilitating the production of high-purity hydrogen gas.

[0372] Example 6 - Ammonia removal in a continuous system, including a pH correction using an automated pH control unit associated with an external alkaline source. The catholyte and anolyte compartments are separated by a cation exchange membrane (CEM), Nafion 212, 50 pm thickness

[0373] The electrochemical system was operated continuously for 18 hours at a flow rate of 3 liters / hour for removing ammonia from simulated wastewater including ammonia at a concentration of lOOmgN / L. This treatment is performed while maintaining the pH level at the anolyte compartment at a pH above about 5 using a pH control unit and external alkaline source.

[0374] Example 7 - Ammonia removal in a continuous system, including pH correction using a bypass pump and produced catholyte solution. The catholyte and anolyte compartments are separated by a cation exchange membrane (CEM)The system is operated continuously to remove ammonia from wastewater while maintaining the pH level in the anolyte compartment at a pH level above 5.

[0375] An electric field is applied between the cathode and the anode to start the purification process. First, the catholyte solution produced at the catholyte compartment reaches a pH level above 12. In parallel, the pH in the anolyte compartment reaches a pH level below pH 5. After and / or while evaluating the pH levels using pH sensor(s) in the compartments, a positive displacement pump, i.e., a bypass pump, transfers a portion of the produced catholyte solution to the anolyte compartment. This transfer raises the pH level in the anolyte compartment and maintains its pH level above pH 4.

[0376] Although the disclosure is described herein in conjunction with specific embodiments thereof, it is evident that numerous alternatives, modifications, and variations that are apparent to those skilled in the art may exist. Accordingly, the disclosure embraces all such alternatives, modifications, and variations that fall within the scope of the appended claims. It is to be understood that the disclosure is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth herein. Other embodiments may be practiced, and an embodiment may be carried out in various ways.

[0377] While certain embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to the embodiments described herein. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the present invention as described by the claims, which follow.

Claims

CLAIMS1. An electrochemical wastewater system comprising:an electrochemical cell comprising at least two liquid compartments, comprising an anolyte compartment and a catholyte compartment separated by a membrane, wherein the anolyte compartment is configured to oxidize contaminants in the wastewater upon application of an electric field;a wastewater tank connected via a first conduit assembly to one or more inlets of the electrochemical cell;an anolyte outlet, configured to output treated wastewater; andone or more catholyte outlets comprising:a first catholyte outlet comprising a first valve configured to selectively permit a gas output from the catholyte compartment, thereby facilitating a liquid pressure in the catholyte compartment that directs passage of at least a portion of a catholyte solution produced upon the application of the electric field, through the membrane to the anolyte compartment; and / ora second catholyte outlet configured to enable output of a catholyte solution produced upon the application of the electric field, the second outlet being connected to a second conduit assembly bypassing the membrane, wherein the second conduit assembly is further connected to the one or more inlets of the electrochemical cell and / or the wastewater tank to enable transfer at least a portion of the produced catholyte solution towards the anolyte compartment and / or the wastewater tank.

2. The system according to claim 1, wherein the pH level in the anolyte compartment is configured to be maintained at a value of at least about pH 4.

3. The system according to claim 1 or 2, wherein the pH value at the anolyte compartment is configured to be maintained at a value in the range of about pH 4-12.

4. The system according to any one of claims 1-3, wherein the amount of an external alkaline agent required to neutralize the total anolyte solution is below 2 molOH / molN.

5. The system according to any one of claims 1-4, wherein the membrane is microporous, thereby enabling the passage therethrough of the produced catholyte solution liquid towards the anolyte compartment.

6. The system according to claim 5, wherein the membrane is a porous diaphragm.

7. The system according to claim 6, wherein the porous diaphragm comprises poly(vinylidene fluoride) (PVDF), Polytetrafluoroethylene (PTFE), polypropylene (PP), and / or polyethylene (PE).

8. The system according to any one of claims 1-7, wherein the second conduit assembly comprises a bypass pump to enable the transfer of at least a portion of the produced catholyte solution to the anolyte compartment and / or the wastewater tank.

9. The system according to any one of claims 1-8, wherein the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution, when the pH thereof is above a pH threshold in the range of about pH 12-14.

10. The system according to any one of claims 1-9, wherein the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution when the pH at the anolyte compartment is below a pH threshold of about pH 4.

11. The system according to any one of claims 1-10, further comprising a catholyte tank fluidly connected to one or more of: the catholyte compartment, a make-up fluid source, the anolyte compartment, and / or a wastewater tank.

12. The system according to any one of claims 1-11, wherein the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution directly from the catholyte compartment to the anolyte compartment.

13. The system according to any one of claims 1-12, wherein the second conduit assembly is configured to transfer at least a portion of the produced catholyte solution to the wastewater tank.

14. The system according to any one of claims 1-13, further comprising a make-up fluid source connected to a catholyte tank or to the catholyte compartment, the make-up fluid comprises water, treated water, salt, wastewater, or any combination thereof.

15. The system according to claim 14, wherein the make-up fluid source comprises wastewater.

16. The system according to any one of claims 1-4 and 8-15, wherein the membrane is a cation exchange membrane (CEM).

17. The system according to claim 16, wherein the CEM comprises a perfluorinated backbone.

18. The system according to any one of claims 1-17, further comprising one or more pH sensors configured to measure pH levels.

19. The system according to claim 18, wherein at least one of the one or more pH sensors is functionally associated with the second conduit assembly, the first valve, and / or the second valve, and is configured to directly or indirectly regulate the transfer of at least a portion of the produced catholyte solution, based on the measured pH level.

20. The system according to any one of claims 1-19, wherein the one or more pH sensors is positioned in, and / or is configured to, measure pH level at one or more of the following: the catholyte compartment, the anolyte compartment, the wastewater tank, and / or any inlet or outlet thereof.

21. The system according to any one of claims 1-20, for use in reducing ammonia concentration in aqueous solution.

22. The system for use according to claim 21, wherein the aqueous solution is wastewater.

23. The system according to any one of claims 1-22, for use in producing hydrogen gas.

24. A method for treating wastewater, the method comprising:allowing wastewater to reach the electrochemical cell of the electrochemical wastewater system according to any one of claims 1-20;applying an electric field between the catholyte and anolyte compartments, to oxidize one or more contaminants in the anolyte compartment and produce a catholyte solution in the catholyte compartment; andtransferring at least a portion of the produced catholyte solution towards the anolyte compartment.

25. The method according to claim 24, wherein the pH level at the anolyte compartment is maintained at a value of at least about 4.

26. The method according to claim 24 or 25, wherein the transfer of the produced catholyte solution is performed via the second conduit assembly around the membrane.

27. The method according to claim 24 or 25, wherein the transfer of the produced catholyte solution is performed through the membrane.

28. The method according to any one of claims 24-25, and 27, wherein the differential pressure on the membrane formed by the liquid pressure is between 150-250 mbar, to enable transfer of the produced catholyte solution through the membrane.

29. The method according to any one of claims 24-28, wherein the pH level at the anolyte compartment is maintained at a value in the range of about 4-12.

30. The method according to any one of claims 24-29, further comprising sensing, using a pH sensor, the pH level at one or more of: the catholyte compartment, the anolyte compartment, a wastewater tank, any outlet or inlet thereof, or any combination thereof.

31. The method according to any one of claims 24-30, further comprising adding a makeup fluid to the catholyte tank or compartment from a make-up fluid source.

32. The method according to any one of claims 24-31, further comprising collecting hydrogen gas produced during the treatment from the first valve or from the second conduit assembly.

33. The method according to any one of claims 24-32, wherein the one or more contaminants comprises ammonium.

34. The method according to claim 33, wherein the ammonium is converted to nitrogen gas during the treatment.

35. The method according to any one of claims 24-34, further comprising collecting the treated wastewater.

36. The method according to claim 35, wherein the collection of the treated wastewater is from the anolyte outlet.

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