Water desalination systems

Abstract

Systems, devices, and techniques described herein relate to iron-based desalination of water. In some cases, an inflow of water including sulfate, chloride, and sodium can be received. A sulfate reduction process may lower the concentration of sulfate. A plurality of iron nanoparticles may capture the chloride and the sodium. The iron nanoparticles may at least partially include Zero Valent Iron (ZVI). An outflow of the water may be emitted. At least some of the sulfate, the chloride, and the sodium may be omitted from the outflow.

Description

WATER DESALINATION SYSTEMSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional App. No. 63 / 498,795, which is titled “Water Desalination Systems,” filed on April 27, 2023, and is incorporated by reference herein in its entiretyBACKGROUND

[0002] The vast majority of the Earth’s water is saline. Some sources estimate that only about 2.5% of the Earth’s water is freshwater Saline water (defined as the sum of sodium and chloride content) however, is typically unusable as drinking water and for many agricultural uses. According to the United Nations (UN), 14% of the world’s population will encounter water scarcity by 2025. Some communities, such as Saudi Arabia and Kuwait, already rely on desalination to supply drinking water and fresh water for agricultural uses

[0003] With the increasing pressure to find usable water resources for drinking, industrial, agricultural, and livestock uses, a variety of technologies are in development to improve water quality. Various governmental agencies, such as the United States (US) Environmental Protection Agency (EPA) require factories to reduce an amount of Total Dissolved Solids (TDS) in wastewater. TDS include various ions and particles that can pass through a filter with pores of around 0.45 microns in size. Water with a high TDS level can significantly disrupt the water balance of biological cells, which can sometimes lead to death. In addition, water with a high TDS level may be opaque, which may reduce photosynthesis in plants exposed to the water. A high TDS level may also increase water temperature. Accordingly, the US EPA requires agricultural water to have a TDS of 1,500 milligrams per liter (mg / L) or less and drinking water to have a TDS of 500 mg / L or less. Because most of the earth’s surface water and groundwater exceeds these standards, most surface water and groundwater is unsuitable for agricultural, industrial, or drinking uses. Desalination technologies are increasingly essential for providing safe water to farms and individuals throughout the world. Desalination techniques are also required by many industries that produce saline water as a result of industrial processes.

[0004] Various desalination technologies have been utilized to remove salt ions from saline water. One example technique is distillation. In a distillation process, saline water can be heated, leading to water evaporation The evaporated water can be condensed and collected as desalinated water. Another example desalination technique is Reverse Osmosis (RO). In an RO process, saline water is pressurized on a first side of a water-permeable membrane. Solute in the saline water (e.g , salt) remains on the first side (brine or reject), and substantially pure water (permeate) can pass through to the second side of the water-permeable membrane through the membrane itself. In addition to distillation and RO, Ion Exchange (IX) and electrodialysis may be used to desalinate water. In general, these processes have relatively high energy, materials, and / or chemical costs, and produce sludge and other waste materials that require handling and dispositionBRIEF DESCRIPTION OF THE DRAWINGS

[0005] The detailed description is set forth with reference to the accompanying figures. In the figures, the leftmost digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items or features.

[0006] FIGS. 1A and 1 B illustrate an example desalination system in accordance with various implementations of the present disclosure.

[0007] FIG. 2 illustrates an example desalination system in accordance with various implementations of the present disclosure.

[0008] FIG. 3 illustrates an example environment for controlling a desalination system.

[0009] FIGS. 4A and 4B illustrate examples of iron nanoparticles configured to adsorb sodium (Na) and chlorine(Cl) atoms.

[0010] FIG. 5 illustrates an example process for removing at least one solute from water.

[0011] FIG. 6 illustrates an example of a desalination tank.

[0012] FIG. 7 illustrates exploded and interior views of an example desalination tank in accordance with various implementations of the present disclosure.

[0013] FIG. 8 illustrates a first view of an example desalination system including multiple example desalination tanks.

[0014] FIG. 9 illustrates a second view of the example desalination system including multiple desalination tanks.

[0015] FIG. 10 illustrates a view of two desalination tanks that can be arranged in a side-by-side fashion in an example desalination system.

[0016] FIG. 11 illustrates a side view of an example desalination system including multiple desalination tanks.

[0017] FIG. 12 illustrates various views of a settling tank of an example desalination system.

[0018] FIG. 13 illustrates at least one example device configured to enable and / or perform various functionality discussed herein.DETAILED DESCRIPTION

[0019] Various systems, devices, and methods described herein relate to improved techniques for removing solutes from water. In particular cases, water can be efficiently and quickly desalinated, and have a sulfate concentration lowered, using various techniques described herein.

[0020] In various implementations, a desalination system includes a sulfate reduction portion. As used herein, the term “sulfate,” and its equivalents, may refer to the fully oxidized ionic form of sulfur, typically represented as a polyatomic anion with the empirical formula SO / . Sulfate, or sulphate ion, may be present in particulates and / or in aqueous solution in combination with metal and / or hydrogen ions, for instance. Sulfates occur widely in everyday life, and salts, acid derivatives, and peroxides of sulfate are widely used in industry For example, sulfates are salts of sulfuric acid and many are prepared from that acid. Sulfate reduction may be desirable for producing water with lower sulfate concentrations. For instance, influent water may have a relatively high sulfate concentration, such as 4000 mg / L, or more than 3000 mg / L. The influent water may be seawater, for instance. In some scenarios, a significantly lower sulfate concentration, such as less than 500 mg / L sulfate, may be desired in water discharged from the desalination system. Therefore, the desalination system may include the sulfate reduction portion in order to lower the sulfate concentration in the final effluent water. The sulfate reduction portion may include one or more sulfate reduction cells (e.g., tanks), for instance.

[0021] In some examples, the desalination system includes a desalination portion, which may include one or more desalination tanks. The desalination tank(s) may receive saline water from the sulfate reduction cell(s) of the desalination system, for example. A desalination media, such as an iron media, may be input into the desalination tank(s) or held within the desalination tank(s). In various implementations, the iron media includes a slurry containing zero valent iron (ZVI) particles. As used herein, the term “Zero Valent Iron (ZVI),” “zerovalent iron,” “nonvalent iron,” “Fe(0),” and their equivalents, can refer to one or more iron atoms with a valency of zero. Furthermore, the ZVI particles may include ZVI nanoparticles (e.g., nano-media). As used herein, “nanoparticle” generally refers to a particle ranging in size from 1 to 100 nm, and nano-media generally refers to a media consisting of nanoparticles. Other sizes of iron particles or iron media are contemplated for use in the desalination system.

[0022] In addition to ZVI, in some examples, an oxidizing agent is introduced into the desalination tank(s) In particular cases, the oxidizing agent includes a gas that produces bubbles in a fluid mixture of the saline and desalination media in the desalination tank(s). Solutes in the saline water are captured and / or removed due to the presence of the desalination media. For instance, oxidation of the ZVI nanoparticles results in capture of solutes such as sodium and chloride ions in the saline The oxidizing agent, in various cases, can greatly increase the speed and efficiency of solute capture by the ZVI nanoparticles. For instance, using techniques described herein, at least 80% of sodium and chloride can be removed from saline water in less than one day (e.g., eight to 10 hours).

[0023] In various cases described herein, the sulfate reduction cell(s) and the desalination tank(s) are part of a continuous, feed-through desalination system. For example, the sulfate reduction tank(s) and the desalination tank(s) are part of a fluid circuit that receives saline water at an inlet and produces desalinated water at an outlet. Various structures within the desalination system can enhance the speed and efficiency of the continuous system These structures optionally include baffles, one or more settling tanks, one or more aeration tanks, physical filters, valves, pumps, or any combination thereof In some cases, a standalone desalination system described herein can be transported to a remote site (e.g., in a boxcar or other modular housing) and used to treat water with minimal energy expenditure.

[0024] Various implementations of the present disclosure will now be described with reference to the accompanying figures.

[0025] FIGS. 1A and 1 B collectively illustrate an example desalination system 100 in accordance with various implementations of the present disclosure. In some implementations, desalination system 100 may include one or more sulfate reduction cells 102 As used herein, “sulfate reduction cell,” and its equivalents, may refer to a variety of types of tanks, vessels, chambers, and / or other associated equipment that is used to lower the concentration of sulfate in water. Example desalination system 100 may also include at least one desalination tank 104. Desalination using desalination tanks 104 will be described in greater detail relative to FIGS. 2-4B, below. Example desalination system 100 may also include at least one carbon source feed unit 106, one or more aeration units 108, at least one desalination media feed unit 110, an air injector unit 112, and / or additional associated equipment. Note that example desalination system 100 in FIG. 1A depicts four sulfate reduction cells 102, including sulfate reduction cell 102-a, sulfate reduction cell 102-b, sulfate reduction cell 102-c, and sulfate reduction cell 102-d. Similarly, four desalination tanks 104 are shown. A desalination system may have more or less of these cells and / or tanks or other amounts of components.Alternatively or additionally, the components may be arranged in series or parallel relative to water flow through the system, for instance

[0026] As illustrated in FIG. 1 A, water may progress from the left side of the drawing page toward the right side. The water may flow passively (e.g., via gravity) and / or actively (e.g., via the actions of one or more pumps). Example systems described herein may use significantly less energy than RO systems. In various implementations, the desalination system 100 can be used to desalinate industrial runoff, mining wastewater, seawater, or the like. In some cases, the desalination system 100 can be used to reduce total dissolved solids (TDS) levels in saline water below acceptable levels (e.g., as defined by the US EPA) for disposal into the ground, for agricultural uses, for drinking water, or the like.

[0027] In general, desalination system 100 may be viewed as including a sulfate reduction portion 114 and a desalination portion 116. In the example depicted in FIG. 1A, the sulfate reduction portion 114 includes at least the sulfate reduction cells 102 and the ethanol feed unit 106. The desalination portion 116 includes at least the desalination tanks 104, the desalination media feed unit 110, and the air injection unit 112. Note that the inclusion of components in the sulfate reduction portion 114 and / or a desalination portion 116 is meantfor illustration purposes and is not meant to be limiting. Other descriptions of the components of the desalination system 100 are contemplated. For instance, in some examples, the aeration unit 108 may be viewed as a component of the sulfate reduction portion 114 of desalination system 100.

[0028] In various implementations, as suggested by the arrows in FIG. 1A, the desalination system 100 receives influent water 118 into the sulfate reduction portion 114. The water flows through the desalination system 100 generally from left to right on the drawing page of FIG. 1A, passing through at least one of the sulfate reduction cells 102, through the aeration unit 108, and into the desalination portion 116. The water continues through at least one of the desalination tanks 104, and eventually exits the desalination system 100 as effluent water 120 (e.g., product water).

[0029] FIG. 1 B illustrates a detailed view of the sulfate reduction portion 114 of desalination system 100 in accordance with various implementations of the present disclosure. In some examples, one or more of the sulfate reduction cells 102 may be biological sulfate reduction cells. In the example of biological sulfate reduction, the sulfate reduction cell(s) 102 of the desalination system 100 may represent anaerobic columns for biological sulfate reduction. As used herein, the term “anaerobic column,” and its equivalents, may refer to a vessel for treating water by encouraging growth of anaerobic bacteria within the vessel for the purpose of converting organic matter into biogas in an oxygen-free environment. For instance, the anaerobic column is designed to support the biological process, or biological growth. As such, a carbon source feed unit 106 may provide a carbon source, such as ethanol, to feed the biological process in the anaerobic column(s).

[0030] As suggested in FIG 1 B, influent water 118 may enter the sulfate reduction portion 114 of desalination system 100. The influent water 118 may be directed into one of the sulfate reduction cells 102. The sulfate reduction cell 102 may contain media 122 (e.g., biological growth media) intended to support biological growth, such as growth of anaerobic bacteria. In some examples, the sulfate reduction cells 102 may be cylinder shaped cell or vessel, the bottom half of which is filled with or contains media 122 for biological growth. In some examples, water may be directed to move up through the media 122. The media may contain mixed carbon materials easily decomposed by bacteria such as compost, mulch, or BioChar, or liquids such as ethanol or calcium lactate. For instance, the media may includeat least one of a cell growth media, granulated activated carbon (GAC), BioChar, or any other suitable media for encouraging biological growth of anaerobic bacteria and retention of the anaerobic bacteria within the sulfate reduction cells 102.

[0031] In some examples, a carbon source and / or other food source for biological growth may be fed to the sulfate reduction cells 102 from the carbon source feed unit 106. Some example carbon sources include ethanol, sodium bicarbonate, acetate, glucose, propionate, lactate, formate, etc. In some examples, convenient or readily available materials, such as some industrial wastes, may be used as a carbon source for cost effective resource management For instance, a carbon source could include chicken manure, dairy manure, sawdust, or any of a variety of other carbon-containing materials. The carbon source feed unit 106 may include a tank for holding ethanol or another carbon source, and any of various valves, pumps, meters, tubing, piping, and the like for supplying the carbon source to the sulfate reduction cells 102. The carbon source may be fed continuously and / or intermittently. Biological growth, such as growth of anaerobic bacteria (e.g., sulfate reducing bacteria) fed by the carbon source, may consume sulfate and / or convert sulfate to sulfide as the carbon source is consumed.

[0032] As the water continues through the sulfate reduction cells 102, the water may also pass through a sulfide capture media 124 (e.g., sulfide reduction media), such as spent iron or BioChar. Therefore, the sulfide will be retained in the sulfate reduction cells 102 (e.g., column), and water flowing out of the sulfate reduction cells 102 will have a lower sulfate concentration than the influent water 118. Thereafter, the water may be treated in series via a second sulfate reduction cell 102 and / or additional sulfate reduction cells 102, to potentially lower the sulfate concentration further. The carbon source, such as ethanol, may also be fed to the additional sulfate reduction cells 102, such as from carbon source feed unit 106, as food source for biological growth. Eventually, reduced sulfate water 126, such as water with a lower sulfate concentration than the original influent water 118, may pass out of the sulfate reduction portion 114 and continue toward the desalination portion 116 (FIG. 1A).

[0033] In some implementations, sulfate reduction cells 102 are relatively inexpensive and can be operated in relatively passive manner. Sulfate reduction cells 102 may have relatively lower chemical costs and produce a lower volume of sludge that reguires handling and disposition, compared to other methods, such as reverse osmosis, iron exchange, or distillation. The sulfate reduction cells 102 may be a simple to construct and simply use a carbon source to drive the bacterial reactions. In addition, the effluent typical of sulfate reduction cells 102 fits well with the operational parameters of the desalination portion 116 of the desalination system 100, such as circumneutral to alkaline pH and modest alkalinity (<250 mg / L). Sulfate reduction cells 102 may utilize sulfate-reducing bacteria (SRB) to (1) reduce sulfate to sulfide, precipitate divalent heavy metals to sulfide solids, and produce alkalinity in proportion to carbon utilization by the microbial population. High metal concentrations may be removed as sulfides, carbonates or oxides, acidity decreases, and pH increases.

[0034] In various implementations, a carbon source, such as ethanol, may be fed continuously into a sulfate reduction cell 102 as a source of chemical oxygen demand (COD) to achieve reduction Ethanol theoretically produces 2.09 mg COD / mg ethanol. The reactors are filled with media 122, as described above, needed for bacterial support. The basic microbial processes include the following generalized reactions. For sulfate and carbon, utilization by the sulfate reducing bacteria produces sulfide (dissolved and as a gas) and alkalinity as shown in the following reaction.The reaction shown is an overall representation of several microbial processes and chemical pathways The sulfide produced will be partially deprotonated and solubilized based on ambient pH:SO42- + 2CH2O ^ H2S + 2HCO3- (1)

[0035] Any divalent metals (such as zinc, copper, iron, lead) in the water will react with sulfide and precipitate as sulfide solids:H2S + M2+^ MS(s) + 2H+ (2) wherein “M” refers to a metal ion.

[0036] Excess sulfide will off-gas or form elemental sulfur:2HS + O2> 2SO + 2OH (3) and / or convert back to sulfate in high 02 waters:2HS- + 4O2= 2SO42' +2H+(4)

[0037] As noted above, the sulfide solids will pass through a sulfide capture media 124 (e.g., sulfide reduction media). Therefore, the sulfide will be retained in the sulfate reduction cells 102 (e.g., column), and water flowing out of the sulfate reduction cells 102 will have a lower sulfate concentration than the influent water 118. The reduced sulfate water 126, or effluent water from the sulfate reduction portion 114, may then be directed to aeration unit 108 and / or the desalination portion 116. Aeration unit 108 may effectively act as a feed tank for desalination portion 116. In some examples, aeration of the water after treatment in the sulfate reduction portion 114 may help improve the results of treatment in the desalination portion 116. In various cases, the water may be aerated by introducing gas bubbles into the water. The water in aeration unit 108 may be aerated by the same injector unit 112 that feeds air to the desalination portion 116, for instance. The water will then pass to the desalination portion 116 of the desalination system 100.

[0038] Referring again to FIG. 1A, the desalination portion 116 of desalination system 100 will now be described. The desalination portion 116 of desalination system 100 utilizes a desalination media (e.g., ZVI, ZVI, nanoparticles, nano-media, iron nanoparticles, etc.) and compressed gas (e g., air, oxygen, etc.) to desalinate water. The desalination tanks 104 may be connected to one another in series and / or parallel The saline water may first pass through a first desalination tank 104-a. The desalination tanks 104 may have one or more inlets and / or one or more outlets. For instance, the desalination tanks 104 may receive the saline water (e.g., reduced sulfate water 126) by an inlet and may release the saline water by an outlet. The desalination tanks 104 may have any suitable shape for temporarily storing the saline water. For instance, the desalination tanks 104 may be cylindrical, spherical, prismatic, or the like. The desalination tanks 104 may have one or more walls in contact with the saline water. The walls may include, for instance, a material resistance to degradation by the saline water, such as plastic (e.g., cross-linked polyethylene, fiberglass reinforced plastic, etc ), metal (e.g., steel), or the like. (Note: similar material descriptions, provided above and below, may also apply to the sulfate reduction cells 104.)

[0039] Water may flow through a portion of a fluid circuit into one or more desalination tanks 104 (e.g., the desalination tank 104-a, the desalination tank 104-b, etc., or any combination thereof). The fluid circuit may include, for example, at least one of pipes, tubes, any vessel through which fluid can flow, or the like. In some cases, the water can flow via hydrostatic pressure. For instance, a saline water tank may be positioned at a higher elevation than the desalination tank(s) 104, thereby generating a hydrostatic pressure. Gravity may propel the saline water from thesaline water tank to the desalination tank(s) 104, in various implementations. Accordingly, in some cases, the water can passively flow into the desalination tank(s) 104 from the saline water tank.

[0040] In some cases, multiple desalination tanks 104 can be connected to each other in series. For instance, an outflow pipe of one desalination tank 104 may be connected to an inflow port of another desalination tank 104, such that water flowing through the desalination tanks 104 may be desalinated by both desalination tanks 104. When multiple desalination tanks 104 are connected to each other in series, a greater amount of sodium and chloride may be extracted from water in a single pass through the system, as compared to treatment using a single one of the desalination tanks 104. In some examples, multiple desalination tanks 104 can be connected to each other in parallel. For instance, an inflow pipe of one desalination tank 104 may be connected to an inflow pipe of another desalination tank 2102, such that water flowing through the desalination tanks 104 may be split between the two (or more) desalination tanks 104 When multiple desalination tanks 104 are connected to each other in parallel, an overall flow rate through the desalination tanks 104 may increase.

[0041] In various implementations, a portion of the fluid circuit extending between the saline water tank (e g., aeration unit 108) and the desalination tank(s) 104 may include an inflow valve. The inflow valve may include any of various types of valves. For instance, the inflow valve may include at least one of a ball valve, a butterfly valve, a choke valve, a diaphragm valve, a gate valve, a globe valve, a knife valve, a needle valve, a pinch valve, a plug valve, a solenoid valve, a spool valve, or the like. (Note: similar fluid circuit component descriptions, provided above and below, may also apply to the sulfate reduction cells 104.)

[0042] In some cases, the inflow valve may be connected in series between the saline water tank and the desalination tank(s) 104. In various implementations, the inflow valve may selectively allow or prevent the passage of water from the saline water tank to the desalination tank(s) 104. For instance, when the inflow valve is in an “open” position, the water may flow from a saline water tank (not illustrated) to the desalination tank(s) 104 through the inflow valve. When the inflow valve is in a “closed” position, the inflow valve may prevent the flow of water from the saline water tank to the desalination tank(s) 104 through the inflow valve. In some cases, the inflow valve may limit or otherwise control the flow of water between the saline water tank and the desalination tank(s) 104. For example, when the inflow valve is partially opened, the inflow valve may limit the flow of water from the saline water tank to the desalination tank(s) 104.

[0043] In various examples, desalination media is introduced into one or more of the desalination tanks 104 from desalination media feed unit 110. For example, the desalination media is introduced as a slurry that is provided through one or more pipes that are coupled with inlets on the top surfaces of the desalination tanks 104 The desalination media, for instance, includes water and ZVI nanoparticles. When introduced to the saline water in the desalination tanks 104, the ZVI nanoparticles may capture sodium, chloride, and other solutes within the saline. The desalination media will be described in greater detail below, relative to FIGS. 4A and 4B.

[0044] In various implementations, the desalination portion 116 may include an injector 112, which may inject an oxidation agent into the fluid circuit of the desalination portion 116 such that the oxidation agent enters the water before the water enters the desalination tank(s) 104. As noted above, the injector 112 may also inject the oxidation agent into the aeration unit 108. As used herein, the term “oxidation agent,” and its equivalents, can refer to a substance that initiates or otherwise facilitates oxidation of a chemical species. In various implementations, theoxidation agent may cause, or exacerbate, oxidation of the ZVI in the desalination media that has been introduced into the desalination tank(s) 104. The oxidation agent may be in a solid form, a liquid form, an aqueous form, or a gaseous form. Some examples of the oxidation agent include at least one of oxygen (O2), ozone (O3), hydrogen peroxide (H2O2), any other electron acceptor that does not introduce additional contamination (e.g., that would increase TDS) into the saline water, or the like. The injector 112 may include any device configured to input the oxidation agent into the fluid circuit (e g., into saline water present in the fluid circuit). For instance, the injector 112 may be a fluid injector, a gas injector, or a liquid injector. In some cases, the injector 112 includes an air compressor or source of compressed air (e.g , a tank that holds compressed air).

[0045] Although not illustrated, in some cases, the injector 112 may inject a reducing agent (e.g., CO) into the water in order to control one or more chemical reactions performed in the desalination tank(s) 104. For instance, if iron in a desalination tank 104 becomes clogged with halite, it might be advantageous to reduce the iron to undog the desalination tank 104.

[0046] In some cases, the injector 112 can be selectively controlled by an external controller (not illustrated), which activates the injector 112 in response to identifying that one or more conditions are present. For example, the external controller could cause the injector 112 to deliver the oxidation agent to water in the fluid circuit in response to receiving a user input requesting the delivery of the oxidation agent.

[0047] The water may flow into the desalination tank(s) 104, and the desalination tank(s) 104 may at least partially desalinate the water. When sodium and chloride ions dissolved in the water contact the iron nanoparticles in the desalination media, the ions may become attached to the iron nanoparticles. Accordingly, the sodium and chloride ions may be retained on the desalination tank(s) 104, and the salinity of the water may be reduced.

[0048] In various implementations, the desalination system 100 can further include a heater (not illustrated) that provides heat to the water in the fluid circuit. The heater can provide heat to the sulfate reduction cells 102 and / or to the desalination tank(s) 104, however, in some examples, the heater may provide heat to a component of the fluid circuit that is upstream of the sulfate reduction cells 102 and / or the desalination tank(s) 104. In some implementations, the heat provided by the heater may increase the temperature of the water flowing through the desalination system 100, which may improve the sulfate reduction process and / or increase the adsorption rate of the sodium and chloride ions on the iron nanoparticles. Various initial experiments indicate that the desalination rate increases significantly if the water is heated from 17°C to 35°C. In some cases, a rate of the desalination (e.g , in terms of sodium and / or chloride removed from the water over time) may increase by 10 to 15% if the water is heated by 10°C. In various implementations, the heater could include an electrically resistive material configured to emit heat when electric current runs through the resistive material. In some examples, the heater could include a Peltier element. In some instances, the heater could be a conduction heater, a convection heater, a heat pump, an immersion heater (e g., a tank of heated fluid), a circulation heater, or the like. Any heater known in the art could be utilized as the heater.

[0049] Effluent water 120 (e.g , product water) that has been desalinated by the desalination tank(s) 104 may flow out from the desalination tank(s) 104 In various implementations, the effluent water 120 flowing out of the desalination tank(s) 104 may have a lower concentration of sodium and chloride ions (and / or other solutes) than the water flowing into the desalination tank(s) 104

[0050] A system including the desalination tank(s) 104 optionally includes a recycle pump (not illustrated). The recycle pump may be configured to pump water from an outflow port of a desalination tank 104 and / or a settling tank to the upstream side of the desalination tank 104, and / or to another desalination tank 104 for further treatment. The recycle pump can be, for instance, at least one of a positive displacement pump, an impulse pump, a velocity pump, a steam pump, a valveless pump, or the like.

[0051] In some cases, water output from a desalination tank 104 may be recycled back into the same or another desalination tank 104. For instance, in a recycle mode, an outflow valve may be closed and the recycle pump may be activated, thereby causing the recycled water to flow to an inflow port of a desalination tank 104 An outflow valve can include any of various types of valves. For instance, the outflow valve may include at least one of a ball valve, a butterfly valve, a choke valve, a diaphragm valve, a gate valve, a globe valve, a knife valve, a needle valve, a pinch valve, a plug valve, a solenoid valve, a spool valve, or the like.

[0052] The recycled water may cycle through the desalination tank(s) 104 multiple times and / or for an extended period of time. Accordingly, the desalination tank(s) 104 may further decrease the amount of solute in the recycled water due to additional opportunities for sodium and chloride adsorption by the iron-based desalination filter(s) in the desalination tanks 104

[0053] In some implementations, a sulfate sensor and / or a salinity sensor (not illustrated), or some other component in communication with a sulfate sensor or salinity sensor, may be configured to activate a flow-through mode and / or the recycle mode of the system. The sulfate sensor or salinity sensor may include, or may be coupled to, one or more processors configured to execute instructions stored on memory. When executing the instructions as the system is in the flow-through mode, the processor(s) may compare the measured sulfate or salinity (or electrical current) to a predetermined threshold. In some cases, the threshold may correspond to a predetermined maximum sulfate or salinity, such as a maximum salinity required for agricultural applications (e.g., 1 ,200 mg / L) and / or drinking water (e.g., 500 mg / L). If the measured sulfate or salinity exceeds the maximum, the processor(s) may cause the outflow valve to close, thereby activating the recycle mode. In some cases, the processor(s) may further activate the pump in the recycle mode. In some cases, the processor(s) may further open one or more recycle valve(s) in the fluid circuit in the recycle mode. The recycle valve(s) can include any of various types of valves. For instance, the recycle valve(s) may include at least one of a ball valve, a butterfly valve, a choke valve, a diaphragm valve, a gate valve, a globe valve, a knife valve, a needle valve, a pinch valve, a plug valve, a solenoid valve, a spool valve, or the like. When the recycle valve(s) are open, the recycle pump may pump the recycled water from an outflow of a desalination tank 104 to an inflow port of the same or another desalination tank 104. The processor(s) may further monitor the salinity measured by the salinity sensor in the recycle mode. Note that the sulfate sensor may be located after the sulfate reduction portion 114, with an arrangement of recycle flow within the sulfate reduction portion 114 to enable further sulfate reduction before continuing to the desalination portion 116.

[0054] If the measured salinity is lower than a threshold, the processor(s) may cause the outflow valve to open, thereby activating the flow-through mode. The threshold used to activate the flow-through mode may be the same or different as the threshold used to activate the recycle mode. For instance, the threshold used to activate the flow-through mode may be 50-500 mg / L less than the threshold used to activate the recycle mode. In some cases, the processor(s) may further deactivate the recycle pump in the flow-through mode. The processor(s) may further cause at least one ofthe recycle valve(s) to close in the flow-through mode. In various implementations, the processor(s) may open or close the outflow valve, activate or deactivate the recycle pump, or the like, by transmitting one or more control signals to the recycle pump and / or the outflow valve. Accordingly, the salinity of the water desalinated by the desalination tanks 104 can be controlled automatically. In some implementations, the water desalinated by the desalination tank(s) 104 and output from the outflow valve can be output from the system as desalinated water.

[0055] Although not required, in various implementations, the system may further include an RO system. The RO system may be configured to further desalinate water treated by the desalination tank(s) 104. The RO system can include any reverse osmosis system known in the art. In some cases, the RO system may include a physical filter that captures insoluble particles in the water. The water output from the outflow valve may be received on a first side of a water-permeable membrane. An RO pump (or some other pump within the RO system) may impose a pressure on the water received from the desalination tank(s) 104 (e.g , the water from the outflow valve). The RO pump can be, for instance, at least one of a positive displacement pump, an impulse pump, a velocity pump, a steam pump, a valveless pump, or the like. Due to the pressure, substantially pure water may be output through the water-permeable membrane to a second side of the water-permeable membrane. In some cases, the substantially pure water can be output from the RO system as desalinated water In various implementations, saline water retained on the first side of the membrane of the RO system can be recycled through the fluid circuit. For instance, one or more RO valves may be opened and the RO pump may reverse direction, such that saline water byproduct from the RO system may be output in the fluid circuit as recycled water, and may be recycled through the desalination tanks 104 for further desalination. Thus, unlike other RO systems, the system may refrain from producing highly saline water as a byproduct. The RO valve(s) can include any of various types of valves. For instance, the RO valve(s) may include at least one of a ball valve, a butterfly valve, a choke valve, a diaphragm valve, a gate valve, a globe valve, a knife valve, a needle valve, a pinch valve, a plug valve, a solenoid valve, a spool valve, or the like.

[0056] In some examples, a desalination tank 104, or the desalination portion 116 including the desalination tanks 104, may include a filter to filter out particulate matter in water flowing through the desalination tank 104. In some cases, a filter may prevent iron particles from escaping the desalination tank 104. In some examples, the filter removes the expended desalination media, which may include oxidized iron nanoparticles as well as the solute(s) (e.g., in the form of halite) that have been captured by the nanoparticles. In some examples, the filter may also remove bacterial growth or sludge passed through from the sulfate reduction cells.

[0057] FIG. 2 illustrates another example desalination system 200 in accordance with various implementations of the present disclosure. In some examples, desalination system 200 may be viewed as representing a desalination portion of a larger system, similar to desalination portion 116 of example desalination system 100.

[0058] The desalination system 200 receives saline water from a saline water source 202 That is, the saline water may be influent water into the desalination system 200. In this example, the saline water source 202 may represent water flowing out of a sulfate reduction process, similar to sulfate reduction portion 114 of the desalination system 100 shown in FIGS. 1A and 1 B

[0059] As used herein, the terms “saline,” saline water,” and their equivalents, may refer to an aqueous solution including dissolved salts, metals, solids, other contaminants, or any combination thereof at greater than a threshold concentration (e.g., greater than 3% salinity). In various cases, saline water is unfit for human and / or animalconsumption. For instance, saline may include seawater, industrial waste, mining waste, agricultural waste, or any combination thereof. In some examples, saline water includes brine As used herein, the term “brine,” and its equivalents, may refer to an aqueous solution having greater than 5% salinity. The saline water source 202, for instance, includes a tank. In some cases, the saline water source 202 includes one or more pipes, pumps, tanks, valves, or other structures by which saline water can be transported to the desalination system 200.

[0060] The saline water enters a first desalination tank 204-a through a water inlet 206, which is fluidly coupled to the saline water source 202. In the example illustrated in FIG. 2, the water inlet 206 extends through a sidewall 208 of the first desalination tank 204-a. The sidewall 208 extends from a base 210 of the first desalination tank 204-a. The sidewall 208 may be parallel to a first direction 212 and the base 210 may be parallel to a second direction 214, wherein the first direction crosses the second direction. During operation of the desalination system 200, the first direction 212 may be opposite of a direction of gravity. In some cases, the sidewall 208 is perpendicular to the base 210. In some examples, the base 210 has a polygonal (e.g., rectangular) and / or circular shape. A lid 216 may be removably coupled to the sidewall 208. The sidewall 208, base 210, and lid 216 include one or more materials configured to contain water, such as saline water. In some examples, the sidewall 208 and base 210 include a metal (e.g , stainless steel), a polymer (e.g , polyethylene), glass, or any combination thereof.

[0061] In various implementations, a desalination media source 218 outputs a desalination media into the first desalination tank 204-a via a media inlet 220. In the example illustrated in FIG. 2, the media inlet 220 extends through the sidewall 208 of the first desalination tank 204-a. However, in some cases, the media inlet 220 extends through the lid 216 of the first desalination tank 204-a The desalination media is configured to capture one or more solutes in the saline water output from the saline water source 202.

[0062] The desalination media, in various cases, includes a slurry containing metal nanoparticles. In some cases, the slurry includes iron nanoparticles 222. For example, the iron nanoparticles include ZVI nanoparticles. The slurry, for instance, includes a mixture of water and nanoparticles. In some cases, the slurry includes additional materials.

[0063] As used herein, the term “nanoparticle,” and its equivalents, can refer to a solid particle that is shorter than 100 nanometers (nm) in at least one dimension. In some cases, a nanoparticle can have a diameter of less than 100 nm. An iron nanoparticle, for example, can be a nanoparticle including (and possibly consisting of) iron atoms In some cases, an iron nanoparticle may include a network structure of iron atoms that are covalently bonded to each other. The network structure may be cubic. In some cases the iron nanoparticles may be mixed with aluminum, magnesium and / or copper nanoparticles.

[0064] As used herein, a “size,” “length,” “diameter,” or their equivalents of a particle may refer to a Z-average diameter (e.g , as determined using Dynamic Light Scattering (DLS)). In some cases, a “size,” “length,” “diameter,” or their equivalents, of multiple particles may refer to a Z-average diameter in which the particles have a weighted differential size distribution within ±10% of the Z-average diameter. In various implementations described herein, the iron nanoparticles may, for instance, may be assumed to have spherical shapes, such that a Z-average diameter of the nanoparticles (e.g., generated using DLS) in suspension may be between 1 and 100 nm. In some cases, the nanoparticles may have a Z-average diameter that is between 40 to 60 nm, such as about 50 nm. In some implementations, at least 90% of a (volume or intensity) weighted differential size distribution of the nanoparticles insolution (e.g., generated using DLS) may be between 20 and 80 nm, such as about 50 nm. In some cases, a particle’s length can be defined by microscope measurements (e.g., via at least one optical microscope, an electron microscope, a scanning probe microscope, or the like), settling velocities (e.g., by applying Stokes’ law to a measured velocity of the particle), and / or sedimentation methods

[0065] When ZVI atoms on the surface of the nanoparticles become oxidized, the atoms may be converted into multivalent iron atoms. In some cases, iron can change between a zerovalent state and a multivalent state, such as the trivalent Fe3+form. As used herein, the term “oxidation,” and its equivalents, can refer to a chemical reaction in which at least one atom loses electrons As used herein, the term “reduction,” and its equivalents, can refer to a chemical reaction in which at least one atom gains electrons. In a “reduction-oxidation” or “redox” reaction, electrons are transferred from one chemical species (e.g., a species undergoing oxidation) to another chemical species (e.g , a species undergoing reduction). For example, ZVI can be oxidized according to the following Equation 5:wherein the 4Fe term includes ZVI, and the iron in the 2Fe2C>3 term includes multivalent Fe(lll).

[0066] When ZVI is converted to multivalent iron, the multivalent iron atoms may be charged. Some iron atoms may be negatively charged or positively charged, based on their respective valencies and the pH of the bulk solution. In some examples, sodium and chloride ions dissolved in the saline water may be attracted to the charged multivalent iron atoms on the surfaces of the nanoparticles 222 due to electrostatic forces between the ions and the multivalent iron atoms. In some instances, the sodium and chloride ions may become covalently bonded to each other and / or iron on the surface of the iron nanoparticles. Accordingly, the sodium and chloride ions in the saline water may be adsorbed onto the surfaces of the iron nanoparticles 222.

[0067] A mixture 224 of the saline water and the desalination media travel through a fluid circuit including an interior space of the first desalination tank 204-a. In various cases, the fluid circuit further includes the interior of a second desalination tank 204-b, a third desalination tank 204-c, and a fourth desalination tank 204-d. Each desalination tank, for instance, may have a volume in a range of 1 L to 10,000 L, such as 10 L, 50 L, 100 L, 200 L, 300 L, 400 L, 500 L, 600 L, 700 L, 800 L, 900 L, or 1 ,000 L. The first to fourth desalination tanks 204-a to 204-d are connected to one another in series, such that the mixture 224 travels through the first desalination tank 204-a, then the second desalination tank 204-b, then the third desalination tank 204-c, then the fourth desalination tank 204-d.

[0068] The first to fourth desalination tanks 204-a to 204-d each include baffles 226. The baffles 226 extend parallel to the first direction 212 within the interior of each of the first to fourth desalination tanks 204-a to 204-d In various implementations, the baffles 226 extend from the lid 216 of the corresponding desalination tank among the first to fourth desalination tanks 204-a to 204-d and are spaced apart from the base 210 of the corresponding desalination tank. In some cases, the baffles 226 may be coupled to a floatation device that floats on the surface of the mixture 224 and extends in a direction opposite to the first direction 212 into the mixture 224. In some cases, at least some of the baffles 226 are configured to extend from the base 210 of the corresponding desalination tank among the first to fourth desalination tanks 204-a to 204-d and are spaced apart from the lid 216 and / or an upper surface of the mixture 224. Due to the spacings between the baffles 226 and the walls of the desalination tanks 204-a to 204-d, the fluid circuit within the interior of the desalination tanks 204-a to 204-d may have a winding path through the desalination system 200.

[0069] According to various implementations, the nanoparticles 222 within the mixture 224 are configured to capture one or more solutes within the mixture 224. In various implementations, ZVI (Fe(0)) in the nanoparticles 222 oxidizes within the mixture 224. As a result of the oxidation reaction, the solute(s) are bound to the nanoparticles 222. In various implementations, the solute(s) include one or more metals, such as at least one of copper, zinc, manganese, aluminum, selenium, or one or more radionuclides. In some cases, the solute(s) include dissolved ions, such as at least one of sodium, chloride, phosphate, sulfate, arsenic, nitrate, nitrite, or hypochlorite. In various implementations of the present disclosure, the nanoparticles 222 within the mixture 224 can be used to desalinate the mixture 224.

[0070] In particular cases, the solute(s) in their aqueous form are charged. For example, at least some of the solute(s) may have a positive charge. Examples of solutes having a positive charge include, for instance, sodium ions (Na+), copper ions (Cu2+), zinc ions (Zn2+), manganese ions (Mn2+), aluminum ions (Al3*), or arsenic ions (As5-). The iron oxide in the nanoparticles 222 has a negative charge. Accordingly, the positively charged solute(s) may electrostatically bind to the oxidized nanoparticles 222. Further, at least some of the solute(s) may have a negative charge. Examples of solutes having a negative charge include, for instance, chloride ions (Ch), selenium ions (Sn2’), phosphate ions (PO43), sulfate ions (SO42), nitrate ions (NO3), nitrite ions (NO’), or hypochlorite ions (CIO ). The negatively charged solute(s) may electrostatically bind to the positively charged solute(s) bound to the oxidized nanoparticles 222 Various other mechanisms for capturing solute(s) are also possible.

[0071] Experimentally, it was observed that a batch system, in which saline water was introduced to a ZVI nano media (i.e., a media that includes ZVI nanoparticles) and held in a static vessel, could result in a significant reduction of solute(s) in the water. However, such batch systems were limited by how much of the solute(s) could be captured. In addition, batch systems were observed to take weeks in order to achieve significant capture of the solute(s).

[0072] In various implementations of the present disclosure, solute(s) can be more quickly and efficiently removed from saline water by introducing a gas into the mixture 224. In various cases, the gas is introduced from a gas source 228 and through gas inlets 230 within the base 210 of each desalination tank among the desalination tanks 204-a to 204-d. The gas, for instance, propagates through the mixture 224 in the form of bubbles 232. The bubbles 232 travel through the mixture 224 in the first direction 212.

[0073] The gas in the bubbles 232, in various cases, includes an oxidizing gas that enhances the reaction from ZVI to iron(lll) oxide. The gas, for example, includes oxygen and / or carbon monoxide. In some cases, the gas includes additional gases to prevent explosions, fires, and other risks when the desalination system 200 is operating. For instance, the gas may include nitrogen gas. In some examples, the gas includes air

[0074] In at least a portion of the fluid circuit throughout the desalination system 200, the bubbles 232 move countercurrent to the desalination media within the mixture 224. For example, the nanoparticles 222 may travel in a direction that crosses and / or is opposite to the first direction 212 in at least a portion of the fluid circuit, while the bubbles 232 rise in the mixture 224 in the first direction 212. The baffles 226, in some cases, may cause the nanoparticles 222 and the mixture 224 to flow in a direction that opposes the first direction 212. In some examples, pumps and / or pipes (not illustrated) are included within the interior of the first to fourth desalination tanks 204-a to 204- d to cause the nanoparticles 222 from the desalination media to move countercurrent to the bubbles 232

[0075] To minimize space within the fluid circuit in which the bubbles 232 are not present, in various cases, the gas inlets 230 are distributed throughout the major area of the base 210. In some cases, the gas inlets 230 aredistributed at a substantially even density throughout the base 210. For example, a number of gas inlets 230 per square area at a center of the base 210 may be substantially equal to a number of gas inlets 230 per square area at an edge of the base 210. The distribution of gas inlets 230 may prevent spaces within the desalination tanks 204-a to 204-d in which the bubbles 232 do not traverse, thereby increasing the volume within the fluid circuit in which the oxidizing reaction of the nanoparticles 222 takes place.

[0076] The size of the gas inlets 230 and / or the bubbles 232 may impact the efficiency of the reaction within the desalination system 200. In some cases, an individual gas inlet among the gas inlets 230 (e.g., each gas inlet 230) has a width in a range of 0.001 meter (m) to 0.1 m, a range of 0.001 m to 0.01 m, or the like. In some cases, the number of gas inlets 230 within a single base 210 is in a range of 1 to 1 ,000,000, 10 to 1,000, or 10 to 100.

[0077] Experimentally, it was observed that the rate of the gas entering the desalination tanks 204-a to 204-d can greatly impact the efficiency of the desalination reaction. If the gas is introduced into the desalination tanks 204-a to 204-d at too low of a rate, the reaction may not be significantly sped up by the gas However, if the gas is introduced into the desalination tanks 204-a to 204-d at too fast of a rate, then the reaction may occur so quickly that the solute(s) may be inefficiently bound to the iron oxide. Accordingly, in various implementations of the present disclosure, the gas is introduced into the mixture 224 at a rate in a range defined between a lower threshold and an upper threshold, such as in a range of 0.5 liter per minute (L / min) to 3 L / minute or in a range of 1 L / min to 2 L / min. For example, the gas may be introduced at a rate of 1 gram (g) per minute to 60 g / min, such as at a rate of 1 .5 g / min to 20 g / min

[0078] In various implementations of the present disclosure, the desalination system 200 is a flow-through system that provides greater desalination efficiency than a batch system. Once the mixture 224 traverses the fourth desalination tank 204-d, the mixture 224 flows into a settling tank 234. In some cases, the settling tank 234 lacks baffles 226. In various examples, the settling tank 234 substantially lacks bubbles 232. In some examples, the settling tank 234 is at least partially cone-shaped. When the mixture 232 is in the settling tank 234, the solute-laden nanoparticles 222 spontaneously sink to the bottom of the interior of the settling tank 234 in the form of waste media 236. In various cases, the waste media 236 is removed from the fluid circuit. In some cases, a valve at the base of the settling tank 234 selectively opens, thereby allowing the waste media 236 to drain from the settling tank 234. In some examples, a vacuum line is coupled to the base of the settling tank 234, which pulls the waste media 236 out of the settling tank 234. Once removed, the waste media 236 may be disposed of.

[0079] The remaining mixture 224 in the settling tank 234 flows into a filter 238. The filter 238, in various cases, further removes waste media 236 from the mixture 224. In various cases, the filter 238 is a physical filter that includes activated carbon. For instance, the filter 238 includes a housing (e.g., a polymer and / or metal housing) that encloses activated carbon particles. In various cases, a remaining portion of the nanoparticles 222 bound to the solute(s) is removed from the mixture by the filter 238. The filter 238, in various cases, releases treated water 240. The treated water 240, for instance, is effluent water discharged from the desalination system 200

[0080] According to various implementations of the present disclosure, the desalination system 200 efficiently removes the solute(s) from the saline water. Experimentally, it has been shown that a similar system can remove at least 80% of dissolved sodium chloride from saline and / or brine in less than 10 hours (e g., in a time range that is between 4 and 8 hours).

[0081] Although not specifically illustrated in FIG. 2, additional structures may be added to the desalination system 200. It has been observed that the temperature of the mixture 224 impacts the speed of the desalination process implemented by the desalination system 200. In some examples, the desalination system 200 includes one or more heaters (not illustrated) that increase a temperature of the mixture 224 above a lower threshold of 10, 15, 20, 25, or 30 degrees Celsius (°C) (and below a boiling temperature). Various initial experiments indicate that the desalination rate increases significantly if the water is heated from 17°C to 35°C. In some cases, a rate of the desalination (e.g., in terms of sodium and / or chloride removed from the water over time) may increase by 10 to 15% if the water is heated by 10°C. In some examples, one or more heaters are coupled to the water inlet 206 of the first desalination tank 204-a. In some cases, the desalination system 200 operates in an environment in which an ambient temperature is greater than 20, 25, or 30°C, such that the heater(s) may be unnecessary and / or deactivated.

[0082] In some implementations, the desalination system 200 includes one or more structures configured to control a pH of the mixture 224. It has been observed that the speed and efficiency of the desalination reaction between ZVI nano media and saline, for instance, can depend on the pH of the mixture 224. In some examples, the desalination media stored in the desalination media source 218 has a pH below 7. For instance, the desalination media may include phenols that make the slurry acidic. According to some examples, the desalination system 200 is configured to add a buffer, such as in the form of a buffer solution, to the mixture 224. The buffer may increase a pH of the mixture 224. For instance, the buffer may include bicarbonate. In some cases, the buffer is automatically dispensed through an inlet in one or more of the desalination tanks 204-a to 204-d.

[0083] According to various cases, fluids are propelled through the fluid circuit within the desalination system 200 via passive and / or active forces. In some examples, the desalination system 200 leverages hydrostatic pressure to propel the mixture 224 through the fluid circuit. For example, the saline water source 202 may store the saline at a higher altitude (with respect to gravity) than an outlet of the filter 238. In various cases, the water inlet 206 of the first desalination tank 204-a has a greater altitude than an outlet of the first desalination tank 204-a, such that the mixture 224 flows spontaneously through the first desalination tank 204-a. The inlets and outlets of the second to third desalination tanks 204-b to 204-d, for instance, may have similar relative altitudes. In some cases, the movement of fluids throughout the desalination system 200 are controlled through the fluid circuit via one or more pumps (not illustrated) and / or one or more valves (not illustrated)

[0084] In some examples, various components of the desalination system 200 are controlled by one or more processors (e.g., a controller, computing device, or the like) According to some examples, the processor(s) activate one or more of the components based on a predetermined schedule. For example, the processor(s) may cause a valve in the base of the settling tank 234 to open for a predetermined amount of time (e.g., ten minutes) at a predetermined frequency (e.g., every two hours)

[0085] In some cases, the processor(s) control the components of the desalination system 200 in response to conditions within the desalination system 200 and / or the saline water source 202. In some cases, one or more sensors (not illustrated) are disposed within the fluid circuit, communicatively coupled with the processor(s), and configured to detect at least one parameter of the desalination system 200. Examples of sensors include temperature sensors, salinity sensors, pH sensors, pressure sensors, light sensors, and the like. Examples of parameters detected by the sensors include, for instance, temperature, salinity, pH, pressure, light absorbance, light transmittance, and the like.The processor(s), for instance, may selectively activate components of the desalination system 200 based on one or more parameters detected by the sensor(s) According to various cases, the processor(s) may activate or deactivate an example component in response to detecting that a parameter is above a first threshold or below a second threshold.

[0086] FIG. 3 illustrates an example environment 300 for controlling a desalination system, such as the desalination system 100 described above with reference to FIGS 1A and 1 B and / or the desalination system 200 described above with reference to FIG. 2. The environment 300 includes one or more vessels 302 that accommodate a fluid circuit 304. For instance, the vessel(s) 302 may include any of the tanks or cells used within a desalination system, such as sulfate reduction cell(s) 102 (FIGS. 1A and 1 B), the aeration unit 108, the desalination tank(s) 204 (FIG. 2), the settling tank 234, the filter 238, or any combination thereof. The fluid circuit 304, in various cases, includes a hollow space that is disposed within the vessel(s) 302. In some cases, the fluid circuit 304 includes one or more pipes, tubes, or other structures that connect multiple tanks among the vessel(s) 302 together. A fluid, such as water (with or without dissolved solutes), a carbon source, a desalination media, a gas (e.g., air, oxygen, etc.), or any combination thereof, can be disposed in the fluid circuit 304. In some cases, the fluid flows through the fluid circuit 304. Although not specifically illustrated, in some cases, the fluid circuit 304 includes one or more inlets and / or one or more outlets.

[0087] In various implementations of the present disclosure, a desalination controller 306 is configured to analyze and / or cause modifications to conditions within the fluid circuit 304. In various cases, the desalination controller 306 is configured to optimize the conditions in the fluid circuit 304 to enhance efficient removal of one or more solutes from water disposed in the fluid circuit 304, including, for example, sulfate reduction and desalination. The desalination controller 306 can be embodied in software and / or hardware. For example, the desalination controller 306 includes at least one computing device, such as a server computer, a laptop, a tablet computer, a smart phone, or other type of computer. In various cases, the desalination controller 306 includes one or more processors configured to execute instructions. The instructions, for instance, are stored in memory and / or non-transitory computer-readable media. By executing the instructions, the desalination controller 306 performs various functions described herein.

[0088] In some cases, the desalination controller 306 is located on the premises of the desalination system. For instance, the desalination controller 306 could be packaged with the vessel(s) 302 of the desalination system. In some cases, the desalination controller 306 is located remotely from the premises of the desalination system. For instance, the desalination controller 306, in some cases, is implemented in at least one server computer located at least one kilometer (km) away from the vessel(s) 302.

[0089] Various sensors may be communicatively coupled to the desalination controller 306. As used herein, endpoints are “communicatively coupled,” if they are connected to one another via at least one wired (e.g., electrical, optical, etc ) interface and / or at least one wireless interface (e.g., BLUETOOTH™, cellular, near-field communication (NFC), etc.) over which communication signals can be transmitted between the endpoints. These sensors, in various cases, are configured to detect one or more parameters of the fluid circuit 304. These parameters include at least one of sulfate, salinity, pH, temperature, pressure, light transmittance, or light reflectance, for example.

[0090] At least one sulfate sensor 308, for instance, is disposed within the fluid circuit 304. As used herein, “sulfate sensor" may include a sensor that is able to detect a proxy of the sulfate anion, such as sulfide The sulfatesensor(s) 308 is configured to detect a sulfate level (or a proxy of a sulfate level, etc.) of water in one or more locations within the fluid circuit 304. Examples of the sulfate sensor(s) 308 include, for instance, optical sensors or electrochemical sensors For example, chromatography, turbidimetric, or colorimetric methods, or microfluidic capillary electrophoresis technology may be used by a sulfate sensor 308 in the fluid circuit 304.

[0091] At least one salinity sensor 310, for instance, may also be disposed within the fluid circuit 304. The salinity sensor(s) 310 is configured to detect a salinity level of water in one or more locations within the fluid circuit 304. Examples of the salinity sensor(s) 31 Oinclude, for instance, an electrical sensor configured to detect an electrical conductivity of the fluid in the fluid circuit 304. In various cases, the salinity sensor(s) 31 Oincludes an anode and a cathode that are suspended in the fluid, as well as a power source that applies a voltage across the anode and the cathode. In some examples, the salinity sensor(s) 310detects the electrical conductivity of the fluid by detecting an electrical current between the anode and the cathode. Alternatively, the salinity sensor(s) 310indudes a current source that outputs a current across the anode and the cathode, and then a voltage detector that detects the voltage between the anode and the cathode in order to detect the electrical conductivity of the fluid. In various implementations, the electrical conductivity is proportional to an amount of dissolved solute(s) in the fluid.

[0092] At least one pH sensor 312 is disposed in the fluid circuit 304, for example. The pH sensor(s) 312 is configured to detect a pH of the fluid at one or more positions in the fluid circuit 304. In some cases, the pH sensor(s) 312 include a pH electrode bulb including a membrane (e.g., including glass) that is permeable to H+ ions in the fluid. The pH sensor(s) 312 may further include a reference cell that contains a pH neutral electrolyte solution. An electrical sensor is connected to the pH electrode bulb and the reference cell and is configured to detect a voltage between the pH electrode bulb and the reference cell. If H+ ions in the fluid enter the pH electrode bulb, then a voltage is detected by the electrical sensor. The magnitude of the voltage, for instance, is dependent on an amount of H+ ions in the fluid, and is therefore indicative of the acidity of the fluid.

[0093] At least one temperature sensor 314 may be disposed in the fluid circuit 304. The temperature sensor(s) 314 is configured to detect the temperature of the fluid circuit 304 at one or more positions within the fluid circuit 304. Various types of temperature sensors can be utilized in the environment 300. According to various implementations, the temperature sensor(s) 314 include one or more thermocouples, thermistors, Peltier elements, or any combination thereof. In various examples, the temperature sensor(s) 314 is configured to output an electrical signal indicative of one or more detected temperatures by the temperature sensor(s) 314.

[0094] In some cases, one or more pressure sensor(s) 316 are disposed in the fluid circuit 304. The pressure sensor(s) 316 is configured to detect a pressure at one or more positions within the fluid circuit 304. In some cases, the pressure sensor(s) 316 include one or more capacitive and / or piezoelectric pressure sensors. For example, the pressure sensor(s) 316 include a membrane disposed between a space with a reference pressure and a space within the fluid circuit 304. When the pressure in the space within the fluid circuit 304 is different than the reference pressure, the membrane is configured to deform. In various implementations, the pressure sensor(s) 316 detects the pressure in the space based on an amount of deformation of the membrane. For instance, the capacitance of a capacitor including the membrane as a plate, or an electrical signal output by the membrane (e.g., due to the piezoelectric effect), is indicative of the deformation of the membrane and the pressure in the space.

[0095] According to some examples, one or more light sensors 318 are disposed in the fluid circuit 304. In some cases, the light sensor(s) 318 include one or more light sources (e g., light-emitting diodes (LEDs)) and one or more light detectors (e.g., photodiodes, phototransistors, etc.) configured to detect light emitted by the light source(s) In some cases, the fluid in the fluid circuit 304 is physically disposed between the light source(s) and the light detector(s). An amount of light detected by the light detector(s), for example, is dependent on an amount of the light that is transmitted (e.g , not absorbed) by the fluid in the fluid circuit 304. In some examples, the light detector(s) is configured to detect an amount of light that is both emitted by the light source(s) and reflected by the fluid in the fluid circuit 304. In some cases, a frequency of the light emitted by the light source(s) and detected by the light detector(s) is optimized for absorbance and / or reflectance of a particular material (e.g., oxidized iron nanoparticles) in the fluid disposed in the fluid circuit 304. For example, the absorbance of the light of an aqueous solution of the oxidized nanoparticles at a predetermined concentration may be greater than a predetermined threshold. In various cases, the light detector(s) output an electrical signal indicative of an amount of light absorbed and / or reflected by the fluid in the fluid circuit 304. This signal may be indicative of an amount of the material present in the fluid in the fluid circuit 304.

[0096] The desalination controller 306, in various cases, receives signals from the sulfate sensor(s) 308, salinity sensor(s) 301, the pH sensor(s) 312, the temperature sensor(s) 314, the pressure sensor(s) 316, the light sensor(s) 318, or any combination thereof, that are indicative of parameters detected by the respective sensors. In some cases, the signals include one or more analog signals, and the desalination controller 306 includes one or more analog-to- digital converters (ADCs) configured to convert the signals into digital signals indicative of the detected parameters. In some cases, the signals output by the sensors include digital signals that are indicative of the detected parameters. In various cases, the desalination controller 306 is configured to analyze data (e g., in the form of digital signals) indicative of the detected parameters.

[0097] In various implementations, the desalination controller 306 is communicatively coupled to one or more active elements that are configured to change conditions within the fluid circuit 304. The desalination controller 306, for instance, is configured to output one or more signals (also referred to as “control signals”) to the active elements in order to cause changes to conditions within the fluid circuit 304.

[0098] In various cases, one or more pumps 320 are present in the fluid circuit 304 The pump(s) 320, in various cases, are configured to control pressure differentials between different subspaces in the fluid circuit 304, thereby inducing fluid flow within the fluid circuit 304. The pump(s) 320, for instance, include at least one peristaltic pump, at least one centrifugal pump, at least one diaphragm pump, at least one magnetic pump, or any combination thereof. In some cases, the pump(s) 320 can include one or more propellers configured to cause fluid movement within the fluid circuit 304.

[0099] According to some implementations, one or more valves 322 are present in the fluid circuit 304. The valve(s) 322, for instance, are configured to selectively open or close portions of the fluid circuit 304 to fluid flow In various cases, the valve(s) 322 include check valves, ball valves, butterfly valves, or any combination thereof. Notably, the valve(s) 322 may include at least one valve configured to control liquid (e.g., saline, carbon source, and / or desalination media slurry) flow in the fluid circuit 304 and / or to control gas (e g., air) flow in the fluid circuit 304.

[0100] In various cases, one or more heaters 324 are present in the fluid circuit. The heater(s) 324, for instance, are configured to heat portions of the fluid circuit 304 In some cases, the heater(s) 324 include one or more resistiveelements that output heat when a voltage is applied In some cases, the heater(s) 324 include one or more Peltier elements.

[0101] In some examples, the pump(s) 320 and / or valve(s) 322 are configured to control the flow of fluid between the fluid circuit 304 and one or more external spaces (e.g., receptacles). These external spaces may include a carbon source unit 326 (e.g., carbon source unit 106), a gas source 328 (e.g., the gas source 228), a desalination media source 330 (e.g , the desalination media source 218), a saline water source 332 (e.g., the saline water source 202), a buffer source 334, and one or more waste receptacles 336. In various cases, the gas source 328 is a space that contains a gas (e.g., air and / or oxygen). The desalination media source 330, for instance, is a space that contains desalination media (e.g., nano media slurry). In some examples, the saline water source 332 includes saline water that is to be desalinated by the desalination system. In various cases, the buffer source 334 is a space that includes a buffer solution (e.g., a bicarbonate solution) that can be used to adjust the pH within the fluid circuit 304. In various examples, the waste receptade(s) 336 includes a space that is configured to receive waste media and / or captured solute(s) from the fluid in the fluid circuit 304. These external spaces, for instance, include one or more tanks, tubs, or other containers that are fluidly and selectively coupled to the fluid circuit 304.

[0102] In various implementations of the present disclosure, the desalination controller 306 is configured to control the pump(s) 320, the valve(s) 322, the heater(s) 324, or any combination thereof, based on one or more parameters detected by the sulfate sensor(s) 308, salinity sensor(s) 301 , the pH sensor(s) 312, the temperature sensor(s) 314, the pressure sensor(s) 316, the light sensor(s) 318, or any combination thereof. For example, the desalination controller 306 may output a control signal that activates or deactivates the pump(s) 320, the valve(s) 322, the heater(s) 324, or any combination thereof, in response to determining that one or more parameters are above a first threshold and / or below a second threshold.

[0103] In particular cases, the desalination controller 306 controls the pump(s) 320 and / or the valve(s) 322 in response to detecting that sulfate detected by the sulfate sensor(s) 308 or salinity detected by the salinity sensor(s) 310 is above a threshold. In some examples, the desalination controller 306 causes the pump(s) 320 to recirculate fluid in the fluid circuit 304 until the sulfate or salinity is below the threshold In some examples, the desalination controller 306 causes the valve(s) 322 to block the fluid from being discharged (e.g., into a filter, such as the filter 238, or into a settling tank, such as the settling tank 234), or block water from advancing from the sulfate reducing portion 114 to the desalination portion 116, until the sulfate or salinity is above the threshold. In some cases, the desalination controller 306 causes the pump(s) 320 and / or valve(s) 322 to release carbon source from the carbon source unit 326 or desalination media from the desalination media source 330 in response to detecting that the sulfate or salinity is above the threshold. In some examples, the desalination controller 306 causes the pump(s) 320 and / or valve(s) 322 to release saline water from the saline water source 332 into the fluid circuit 304 in response to detecting that the sulfate or salinity is below the threshold.

[0104] According to some cases, the desalination controller 306 controls conditions within the fluid circuit 304 based on a pH detected by the pH sensor(s) 312. In some examples, the desalination media has a relatively low pH (e.g , due to the presence of phenols added to the desalination media during iron nanoparticle synthesis). It has been observed that the efficiency and speed by which the desalination media removes solute(s) from saline can be enhanced by lowering the pH of the saline added to the fluid circuit 304. In some examples, the desalination controller306 causes the pump(s) 320 and / or valve(s) 322 to release buffer (e.g., water containing bicarbonate or some other type of basic solution) from the buffer source 334 into the fluid circuit 304 in response to detecting that the pH detected by the pH sensor(s) 312 is below a threshold.

[0105] In some examples, the desalination controller 306 adjusts conditions within the fluid circuit 304 based on a temperature detected by the temperature sensor(s) 314. In various implementations, it has been observed that the efficiency and speed by which the desalination media removes solute(s) from saline can be enhanced by controlling the temperature of the fluid in the fluid circuit 304 to be in a range of 25°C to 50°C. In various cases, the desalination controller 306 causes the heater(s) 324 to activate in response to determining that a temperature detected by the temperature sensor(s) 324 is below a threshold.

[0106] In various instances, the desalination controller 306 adjusts the conditions within the fluid circuit 304 based on a pressure detected by the pressure sensor(s) 316. A pressure differential between different locations along the fluid circuit 304 may be indicative of an amount of fluid flow in the fluid circuit 304. In some cases, an initial phase of flow through the fluid circuit 304 is achieved via hydrostatic flow from the saline water source 332 into the fluid circuit 304, wherein the saline water source 332 may be elevated with respect to the fluid circuit 304. However, after a sufficient amount of saline water has left the saline water source 332, in some cases, pressure in the fluid circuit 304 may equilibrate, causing limited to nonexistent fluid flow. In some examples, the desalination controller 306 activates the pump(s) 320 to activate in response to determining that a difference between a pressure detected at a first part of the fluid circuit 304 and a pressure detected at a second part of the fluid circuit 304 is below a threshold.

[0107] According to some cases, the desalination controller 306 may cause the valve(s) 322 to selectively vent gasses in the fluid circuit 304 to an environment outside of the fluid circuit 304 For instance, if the fluid circuit 304 is sealed from an external environment, and the gas source 328 releases gas into the fluid circuit 304, the pressure within the fluid circuit 304 may build to an undesirable level. In various cases, the desalination controller 306 causes the valve(s) 322 to vent fluid in the fluid circuit 304 to the external environment in response to detecting that a pressure detected by the pressure sensor(s) 316 is above a threshold.

[0108] In some examples, the desalination controller 306 selectively causes removal of waste media and / or solute from fluid in the fluid circuit 304. In particular examples, iron nanoparticles capture solute from the fluid during oxidation. The oxidation of iron nanoparticles in the fluid, in various cases, changes the absorbance and / or reflectance of the fluid. For instance, oxidized nanoparticles can cause treated water to appear opaque and / or as an orange color. In various cases, the desalination controller 306 causes the pump(s) 320 and / or valve(s) 322 to release waste media and solute from the fluid circuit 304 and into the waste receptacle(s) 336 in response to determining that a light absorbance and / or reflectance of the fluid in the fluid circuit 304 exceeds a first threshold and / or that a light transmittance of the fluid in the fluid circuit 304 is below a second threshold. The desalination controller 306, in various implementations, determines the light absorbance, reflectance, or transmittance based on signals output by the light sensor(s) 318.

[0109] FIGS. 4A and 4B illustrate examples of iron nanoparticles configured to adsorb sodium (Na) and chlorine (Cl) atoms. FIG 4A illustrates an example environment 400 in which an iron nanoparticle 402 captures a sodium ion (Na+) 404 and a chlorine ion (CI-) 406. Although FIGS. 4A and 4B are described with reference to removing sodiumand chlorine ions, it should be understood that in some cases, other positive and negative ions can be removed from water using similar techniques.

[0110] The iron nanoparticle 402 may include ZVI (Fe(0)). According to various implementations, the iron nanoparticle 402 may have a mean particle size that is less than 1000 nm. For instance, the mean particle size can be calculated by observing a sample of iron nanoparticles under a microscope, measuring lengths of the iron nanoparticles in at least one direction, and then calculating an arithmetic mean of the lengths. For instance, an AMSCOPE 3.5x-180x Light Emitting Diode (LED) Zoom Digital Stereo Microscope with a 10 MP camera could be used to capture an image of the particles (e.g., in or out of solution). Image processing software can be used to perform point counting (e.g., software provided by National scientific and Technical Research Council, Buenos Aries, Argentina). The point counting software may also be used to identify the diameters of the particles.

[0111] In some cases, a length (e.g., a diameter) of the iron nanoparticle 402 may be between 10 and 100 nm, 20 to 80 nm, or 35 to 55 nm. In various implementations, the iron nanoparticle 402 may have a surface area between about 0.1 square meters per gram (m2 / g) to about 25 m2 / g. As used herein, the term “about” can refer to a range of numbers that would be rounded to the number specified. For instance, the term “about 0.1” may refer to a range of 0.05“to 0.14“

[0112] In some cases, when the iron nanoparticle 402 begins to corrode (i.e., oxidize), iron on the surfaces of the particles is hydrolyzed, and hydroxyl (-OH) groups are formed on the surfaces of the particles. The hydroxyl groups on the surfaces are amphoteric, and can have a negative charge or a positive charge depending on a pH of the solution.

[0113] According to some implementations, at least some of the ZVI on the surface of the iron nanoparticle 402 can be oxidized while immersed in water. When the ZVI becomes oxidized, two types of complexes may be formed: FeOOH2+ and FeOOH-. The positively charged FeOOH2+ may electrostatically attract the negatively charged Cl- 406 dissolved in the water. The negatively charged FeOOH- may electrostatically attract the positively charged Na+ 404 dissolved in the water. The electrostatic attraction between the charged complexes and the Cl- 406 and Na+ 404 ions may cause a first layer of Cl- 406 and Na+ 404 ions to be adsorbed onto the surface of the iron nanoparticle 402.

[0114] Once a first layer of Na+ 404 and Cl- 406 is adsorbed onto the surface of the iron nanoparticle 402, additional ions may be further adsorbed onto the first layer. For instance, additional negatively charged Cl- ions 406 may be electrostatically attracted to the positively charged Na+ 404 in the first layer, and additional positively charged Na+ 404 may be electrostatically attracted to the negatively charged Cl- 406 in the first layer. Multiple layers of Cl- 406 and Na+ 404 may assemble on the surface of the iron nanoparticle 402. In some cases, the Cl- 406 and Na+ 404 may form a crystal structure.

[0115] The adsorption of the Na+ 404 and Cl- 406 due to electrostatic forces with oxidized forms of iron in the nanoparticle 402 may occur relatively quickly. As Cl- 406 is attracted to, and attaches to, Fe(OH)4+ functional groups on the surface of the iron nanoparticle 402, a subsequent, slower reaction may take place that also causes desalination. In some examples, the Cl- 406 may further catalyze the oxidation of Fe(0) in the iron nanoparticle 402. Additional Cl- 406 may diffuse through the surface layer of the iron nanoparticle 402 and cause further oxidation of the Fe(0) below the outer surface of the iron nanoparticle 402 and within the interior of the iron nanoparticle 402. Additional layers of Fe-O-CI and Fe-O-Na may be generated within the interior of the iron nanoparticle 402.

[0116] Both reactions (the surface adsorption and capture by iron within the interior of the iron nanoparticle 402) may cause water uptake. In addition, when the iron nanoparticle 402 is submerged in water, the salinity gradient may increase as a distance to the iron nanoparticle 402 decreases, due to the capture of the Na+ 404 and the Cl- 406. Accordingly, an a nano media including iron nanoparticles 402 may aggregate into solid particles that expand in size, due to water uptake and osmosis, when exposed to saline.

[0117] FIG. 4B illustrates an example environment 408 of multiple iron nanoparticles 402 capturing Na and Cl dissolved in water The multiple iron nanoparticles 402 may be packed together. In some cases, spacers 410 may be disposed between the iron nanoparticles 402. Some examples of spacers 410 include a starch (e.g., potato starch), carboxy methyl cellulose, polyvinyl pyrrolidine, or the like. The spacers 410 may prevent the iron nanoparticles 402 from agglomerating. Although not illustrated, in some cases, at least some of the iron nanoparticles 402 may be directly touching each other.

[0118] In various implementations, a pore 412 can be present between the iron nanoparticles 402. In some cases, multiple pores 412 can be present between groups of the iron nanoparticles 402. The pore 412 may be generated based on the geometries of the iron nanoparticles 402 and the spacers 414. In various examples, the pore 412 may have a width of 20-100 nm.

[0119] When the iron nanoparticles 402 are exposed to water in which chlorine and sodium atoms are dissolved, the sodium and chlorine atoms may be adsorbed onto the surfaces of the iron nanoparticles 402. In some cases, the sodium and chlorine atoms may assemble into a halide 414 disposed within the pore 412. The halide 414 may be a crystal including the sodium and chlorine atoms.

[0120] In various implementations, the iron nanoparticles 402 can remove a significant amount of salt from water. For example, in the case of Na and Cl removal from water, a ratio of a weight or mass of Na and Cl removed from saline water by the iron nanoparticles 402 to a weight or mass of iron in the iron nanoparticles 402 (i.e., NaCkFe) can be as much as 20:1.

[0121] In some cases, additional contaminants can be removed from the water by the iron nanoparticles 402. For example, various other solutes described herein can also be captured by the iron nanoparticles 402.

[0122] An example experiment utilizing a desalination system similar to the example systems described above will now be presented. In this example experiment, a desalination system similar to example desalination system 100 depicted in FIGS. 1 A and 1 B was be used to treat saline irrigation water. For instance, the influent water 118 shown in FIGS. 1A and 1 B may represent saline irrigation water. Effective desalination methods may allow use of saline groundwater, seawater, and / or impounded saline agricultural drainage and runoff for crop growth. A desalination system similar to desalination system 100 may be used to treat such saline waters to beneficially provide irrigation for the crop growth

[0123] In this example experiment, synthetic water mimicking a typical saline irrigation water was treated with a desalination system similar to example desalination system 100, which was able to reduce sulfate from 2500 mg / L to less than 250 mg / L in the sulfate reduction portion (similar to the sulfate reduction portion 114 of the desalination system 100 shown in FIGS. 1A and 1 B). In some examples, sulfate at high concentrations may inhibit Na and Cl removal in a desalination process. In the example experiment, after sulfate was lowered by the sulfate reduction portion, a desalination portion (similar to desalination portion 116 of desalination system 100 shown in FIGS. 1A and1 B) was able to reduce sodium (Na) and chloride (Cl) by 50%. Accordingly, the electrical conductivity (EC) decreased from 9.2 mS to about 5 mS. In some examples, water that does not have sulfate removed may only be desalinated by about 10% Using a desalination system, the change in conductivity and sodium and chloride content may allow the effluent water 120 (e.g., discharge) to be used for irrigation of many crops, as well as for other purposes. In other examples, the treated, effluent water (i.e., effluent water 120) may have a TDS below 3000 mg / L and an EC below 4.5 mS, which may be lower than an original TDS and / or EC of the influent water (i.e., influent water 118). In some examples, additional constituents of concern in the water may also be targeted. For instance, a desalination system may also be configured to remove bicarbonate anions from the water.

[0124] A chemical profile of a typical saline irrigation water was used in the example experiment for the influent water. In general, irrigation water often has similar concentrations of chloride, sodium, and sulfate, in contrast to seawater which may have much higher levels of sodium (Na) (10,000 mg / L) and chloride (Cl) (15,000 mg / L) compared to sulfate (2000 to 3000 mg / L). Seawater can be largely desalinated without first removing sulfate. If saline irrigation water contains appreciable sulfate, the sulfate may need to be reduced before Na and Cl can be removed as the presence of sulfate may alter the reaction sequence responsible for Na and Cl removal using some iron-based removal methods, for instance.

[0125] A carbon source for the sulfate reducing bacteria (SRB) in the example experiment was a liquid alcohol (ethanol) source fed at the influent to sulfate reduction cells (similar to sulfate reduction cells 102 shown in FIGS. 1A and 1 B). The ethanol solution also contained 10% of a calcium lactate solution for suppression of bicarbonate produced in the sulfate reduction cells. Water was pulled from a set of 250 L containers via a peristaltic pump. Water flowed from a first sulfate reduction cell in an upflow manner, then to the second sulfate reduction cell, and third sulfate reduction cell in series. Each sulfate reduction cell contained one sampling point on the effluent port between the sulfate reduction cells Overall, the sulfate reduction process used in the experiment included three 55-L sulfate reduction cells, each with 40 L of void volume. Each sulfate reduction cell 102 was approximately 30.5 cm diameter and 91 cm tall. Each sulfate reduction cell contained 3 cm of rock above the inlet piping at the bottom, followed by 6 to 8 cm of vegetable compost and 70 to 80 cm of plastic fluidized media. Two pumps are used, one to deliver raw water and a smaller peristaltic pump was connected to the main raw water feed line to allow carbon dosing of the raw water.

[0126] Carbon dosing in the experiment was set to achieve a chemical oxygen demand (COD) to sulfate ratio of 1 to 1 5 using ethanol with 10% calcium lactate added to suppress carbonate increases produced from microbial metabolism of added carbon substrate. A 48-hr retention time was targeted for sulfate reduction. The flow rate through the system based on this target retention time was 2.5 L / hr. A startup period of roughly 3 weeks was used after inoculation of each of the sulfate reduction cells with 5 mL of anaerobic municipal wastewater treatment sludge. The onset of sulfate reduction was characterized by an oxidation reduction potential (ORP) of around -250 to -400 mv.

[0127] Effluent water from the sulfate reduction portion 114 was directed to the aeration unit, which effectively acted as a feed tank for a desalination portion (similar to the desalination portion 116 shown in FIGS. 1A and 1 B). The aeration unit in this experiment was a 200 L plastic tank. The water was then fed to the desalination portion. In this experiment, a 130 L desalination tank (e.g., reactor) having dimensions of 30.5 cm diameter by 183 cm height was used. This reactor had an air line connected to the bottom of the desalination tank and internal diffuser that bubbledair up through the desalination tank at an external flow rate of 10L of air / min. The air flow was controlled by an air compressor or medium sized aquarium air pump. A small reservoir (2L), or desalination media feed unit, provided the nano-zero valent metal (N-ZVM) slurry to the top of the desalination tank. The dose was predetermined to achieve at least 60% Na and Cl removal over a 2-hour time period. Generally, the N-ZVM was composed of iron nano-particles blended with aluminum and copper metal powder and then treated with organic mixtures to cap and retard rapid oxidation. In other experiments polyphenol / iron salt mixtures could be used for a desalination media The slurry could also be placed in an open ended cannister securely held within the desalination tank.

[0128] In various implementations, the SRB portion of the system may be viewed as the rate limiting step In some examples, the desalination portion may be operated in batches, as sufficient effluent water becomes available from the sulfate reduction portion of the system. In this example experiment, once the aeration unit (e.g., SRB effluent tank) reached about 120L, the water was then pumped to the desalination tank. After 2 hours of treatment in the desalination tank, the treated water was conveyed to a holding tank to settle reaction products prior to discharge.

[0129] Once the system was started, the following samples were collected. At the sulfate reduction cells an influent raw water sample was collected for determination of sulfate, pH, ORP, and EC. During operation, samples were collected on the effluent side of the sulfate reduction cells every 48 hours and also analyzed for sulfate, pH, ORP, and EC. Water collected from the sulfate reduction cells was tested before entry into the desalination tank. The 120 L sample introduced to the desalination tank occurred every 48 hours as it took 2 days to produce sufficient effluent to fill the desalination tank, in this experiment. Analysis of the 120 L samples included sulfate, sulfide, chloride, EC, pH and ORP. Once the desalination tank was started, samples were collected at the end of each 2 hour run for the same analyses. An additional 4 runs were also done to demonstrate the effect sulfate has on suppressing Na and Cl removal via the desalination tank. In these cases, synthetic water was directed directly to the N-ZVM reactor without routing through the sulfate reduction portion for sulfate removal.

[0130] In the experiment, analytical methods for the following analytes included:Sulfate: turbidimetric method using a HACH® 9100 spectrophotometer (HACH COMPANY, of Loveland, CO) Chloride: Ion selective electrode (ISE) methodology using a combination chloride ion specific electrode and meter EC: using a HANNA® EC cell and meter (HANNA INSTRUMENTS USA, of Woonsocket, Rl) pH: using a HANNA® combination, solid state pH electrode and meter ORP: using a HANNA® combination ORP and pH meter COD: using a HACH® COD test kit with block digestor Standard solutions were used to calibrate instrumentation daily.

[0131] The water used in the experiment was made from a mixture of halite (NaCL) salt and magnesium sulfate salts mixed with tap water to achieve the following water composition. 2100 mg / L Cl, 1342 mg / L Na, 2500 mg / L SO4, 7.2 pH (standard units), 9.3 mS EC. Prior to initiation, the sulfate reduction cells were inoculated and run for 5 weeks to determine when peak sulfate reduction occurred. When sufficient sulfate reduction occurred (>85%) the desalination process was started. During the start up period, sulfate reduction began after about 3 weeks and then the sulfate concentration declined substantially from an initial concentration of near 2500 mg / L to under 500 mg / L. At this time, the sulfate reduction cells were allowed to continuously operate. Discharge from the sulfate reduction cells was collected for introduction to the desalination tank. The ORP on the effluent side of the sulfate reduction cells at week3 was approximately -370 mv and declined to -440 mv by week 5. This range of ORP values may be commonly used to guide the startup of sulfate reduction cells, in some implementations.

[0132] Once the process of treating the water in the sulfate reduction cells was started, it took approximately 48 hours of operation for the sulfate reduction cells to produce sufficient water to fill the desalination tank Table 1 displays results from the effluent from the sulfate reduction cells and the effluent from the desalination tank for the entire 14 run time frame (roughly 28 days).Table 1. Results from example desalination system experiment.

[0133] As shown in Table 1, at first the sulfate reduction cells effluent sulfate (SO4) continued to decrease during the run sequence. The sulfate at startup was just under 500 mg / L but dropped to 200 mg / L at run 3 and remained close to this value through run 10. Secondly, as expected, sulfate reduction cells effluent EC did not appreciably change since sulfate reduction typically results in an increase in bicarbonate (and sulfide) concentrations from biological carbon metabolism, off-setting reductions in sulfate. The bicarbonate concentration was dampened somewhat by the addition of calcium as calcium lactate in this experiment, but this was not clear from the effluent data. In addition, the presence of soluble, charged organic species from the lactate and the layer of compost in the reactor cells may have contributed to the observed conductivity readings. The desalination tank was able to reduce electrical conductivity (EC) from about 9 mS to between 5.5 and 4.7 mS, or roughly 47%, on average, suggesting a substantial drop in the salt content of the water. This was validated by the change in chloride (Cl) concentrations which decreased from 2100 mg / L on the influent side to consistently near 1000 mg / L on the effluent side. Assuming Cl and Na are removed in normal molar relationship, sodium would have decreased from 1342 mg / L to about 600 to 700 mg / L. Given the decrease of Na and Cl observed in the effluent, other dissolved constituents such as magnesium, bicarbonate and organic acids would have contributed to a higher observed EC than that predicted from Na and Cl alone. Test runs 11through 14 demonstrate the desalination tank performance without first removing sulfate. In these runs, the conductivity only decreased from 9.0 to only 8.2 or a decrease of only 9% compared to about 50% with sulfate first removed.

[0134] Various improvements are contemplated to both the sulfate reduction portion and the desalination portion of the desalination system. For example, a scale of the sulfate reduction portion may be increased relative to the desalination portion to produce effluent at a rate that matches the operational rate of the desalination tanks. In this experiment a 48-hour retention time was used on the sulfate reduction portion of the system, but could be shortened to 24 hours and even 12 hours, for instance. This could reduce a footprint of the sulfate reduction portion and / or allow faster processing of water. Additionally, the scale and / or arrangement of the desalination portion can be adjusted. For example, instead of a single desalination tank used in this example experiment, multiple cells may be used in series (as shown in the example desalination systems in FIGS. 1A and 2). The use of desalination tanks in series may increase efficiency and / or throughput, and / or may increase the removal rate of the salt content. For instance, the salt content may be reduced by 75 to 80%, rather than 50% as in this experiment. In addition, the desalination system may be controlled via a programmable logic controller (PLC) such that an influent flow rate, air pressure, and air flow are remotely controllable. The desalination system may be fitted with pH, ORP and EC meters on the influent and effluent side of the pilot as explained above. Continued improvements to the desalination system will make the desalination system may be attractive as a mobile source for desalination of irrigation water, irrigation drainage water, and seawater.

[0135] Wide application of a desalination system may be achieved by the addition of a relatively inexpensive means of removing sulfate. The results of the experiment described above suggest that the sulfate reduction portion and the desalination portion are compatible and can be expected to reduce salinity by as much as 50%. Such a result could allow reuse of saline irrigation water without having to blend the saline irrigation water with potable water which is less desirable in terms of resource cost.

[0136] FIG. 5 illustrates an example process 500 for removing at least one solute from water. The process 500 may be performed by an entity including one or more elements of the desalination system 100, the desalination system 200, and / or the environment 300 described above.

[0137] At 502, the entity receives an inflow of water including the at least one solute. In some examples, the solute(s) include sodium and / or chloride, such as in the form of aqueous ions. In some examples, the solute(s) include phosphate, sulfate, arsenic, nitrate, chlorine, calcium, potassium, or any combination thereof. The water, for instance, can include seawater, mining waste, industrial waste, agricultural waste, or any combination thereof. In various cases, the at least one solute includes one or more metals. Examples of metals, for instance, include copper, zinc, manganese, aluminum, selenium, a radionuclide, or any combination thereof. The inflow of water may be received at a sulfate reduction cell, for instance.

[0138] In some examples, the sulfate reduction cell is a biological sulfate reduction cell. The biological sulfate reduction cell may contain biological growth media. The biological sulfate reduction cell may be configured to lower the sulfate concentration in the water by passing the water through the biological growth media. The biological growth media may include granulated activated carbon or biochar, for instance. Furthermore, process 500 may include feedinga carbon source to the biological sulfate reduction cell. The carbon source may include ethanol, or any of a variety of carbon sources suitable for feeding a biological sulfate reduction process.

[0139] At 504, the entity decreases an amount, or decreases a concentration, of sulfate anions in the water In some examples, the entity decreases the amount of sulfate anions by passing the water through the sulfate reduction cell. In various implementations, the entity may lower the concentration of the sulfate in the water from over 2000 mg / L sulfate to less than 500 mg / L sulfate. In some examples, the entity may lower the concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 1000 mg / L sulfate. In yet other examples, the entity may lower the concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 500 mg / L sulfate. Stated another way, in some examples, the entity may lower the concentration of the sulfate in the water by approximately 75% or more. In yet more examples, the entity may lower the concentration of the sulfate in the water by approximately 90% or more. The entity may further decrease the sulfate anions in the water by passing the water through an additional sulfate reduction cell.

[0140] At 506, the entity directs the water from the sulfate reduction cell to a desalination tank In some examples, the entity may direct the water from the sulfate reduction cell to an aeration unit before directing the water to the desalination tank. The aeration unit may be configured to aerate the water from the sulfate reduction cell. For instance, the aeration unit may cause the water to contact an oxygen gas, such as air bubbles.

[0141] At 508, the entity captures at least some of the chlorine atoms and the sodium atoms. In some examples, the at least some of the chlorine atoms and the sodium atoms are captured by a desalination media in the desalination tank. The desalination media may include an iron-based media, zero-valent iron, a plurality of iron nanoparticles, or any of a variety of suitable media. In some examples, such as the plurality of iron nanoparticles, the desalination media may be introduced to the desalination tank as a slurry.

[0142] At 510, the entity emits an outflow of the water from the desalination tank. In some examples, the entity may capture additional chlorine atoms and additional sodium atoms by passing the water through an additional desalination tank. In general, the inflow ofthe water may have a first Total Dissolved Solids (TDS) level and the outflow of the water has a second TDS level, the second TDS level being one half or less of the first TDS level.

[0143] FIGS. 6-12 illustrate additional examples of desalination tanks in accordance with various implementations of the present disclosure. The additional example desalination tanks shown in FIGS. 6-12 will be described briefly below. Some aspects of the additional example desalination tanks shown in FIGS. 6-12 may be similar to aspects described above relative to FIGS. 1 A and 2, and will not be repeated for sake of brevity.

[0144] FIG. 6 illustrates an example of a desalination tank 600 (e.g., desalination vessel). Desalination tank 600 includes an inflow port 602. FIG. 7 illustrates exploded and interior views of an example desalination tank 700 in accordance with various implementations of the present disclosure.

[0145] In various implementations of desalination systems disclosed herein, the desalination tank 700 can be utilized to desalinate saline water. The saline water includes dissolved salts, such as dissolved sodium and chloride ions. In some cases, saline water may include additional components, such as other ions, contaminants, and particles. In various implementations, the desalination tank 700 can be used to remove other types of contaminants from water. For example, the desalination tank 700 may be used to remove dissolved components from water that is not saline water.

[0146] In the illustrated desalination tank 700, saline water may enter through an inflow port 702 (also referred to as an “inlet”). Any pipe through which saline water can flow may be suitable for bringing the saline water to the inflow port 602. For instance, the pipe may include at least one of a metal (e.g., steel, copper, etc.) pipe, a plastic (e g., silicone, Polyvinyl Chloride (PVC), butadiene, etc.) tube, or their equivalents. In some cases, the pipe may include a material that is resistant to degradation by saline water.

[0147] The saline water may flow through the inflow port 702 into the desalination tank 700. A pipe (not illustrated) carrying the saline water may be sealed onto the inflow port 702. For instance, a compressible o-ring (including, e.g., silicone, butadiene, or the like) may be compressed between the pipe and the desalination tank 700. In some cases, the pipe may be chemically bonded or heat-bonded to the desalination tank 700.

[0148] In various implementations, the desalination tank 700 may include a solid housing configured to hold fluid (e.g., water). According to some example implementations, the housing may be equipped with a removable component, through which the interior of the desalination tank 700 may be accessed. For instance, as shown in FIG. 7, the housing may have a removable lid 704.

[0149] According to implementations of the present disclosure, iron may be introduced into the desalination tank 700. In some implementations, the iron may be in the form of iron nanoparticles.

[0150] The iron nanoparticles may be introduced into the desalination tank 700 as a slurry. For example, the slurry may be fed into the desalination tank 700 via a slurry influent line coupled to a slurry port 706 (also referred to as a media inlet). In some cases, the iron nanoparticles may covalently bond, or otherwise stick to one another, wherein pores may be present between the iron nanoparticles. In some cases, the sodium and chloride ions (or another type of dissolved salts in the saline water) may assemble into a cubic crystal structure within the pores. For instance, the sodium and chloride may assemble into halite crystals within the pores.

[0151] By capturing the sodium, chloride, and / or other ions in association with the iron nanoparticles, the desalination tank 700 may be used to extract sodium, chloride, and / or other ions from the saline water, thereby generating desalinated water. In various implementations, the desalinated water may flow out of the desalination tank 700 through an outflow port 708. Any pipe through which water can flow may be coupled with the outflow port 708. For instance, an outflow pipe coupled with the outflow port 708 may include at least one of a metal (e g., steel, copper, etc.) pipe, a plastic (e.g., silicone, PVC, butadiene, etc.) tube, or their equivalents. The outflow pipe may be sealed onto an outlet port 708 of the desalination tank 700. For instance, a compressible o-ring (including, e.g., silicone, butadiene, or the like) may be compressed between the outflow pipe and the desalination tank 700. In some cases, the outflow pipe may be chemically bonded or heat-bonded to the desalination tank 700.

[0152] Although implementations of the desalination tank 700 described with reference to FIG. 7 indicate that water is actively flowing through the desalination tank 700, implementations are not so limited. The iron nanoparticles in the desalination tank 700 may actively capture sodium and chloride ions in saline water that is statically held inside of the desalination tank 700. For instance, various sodium and chloride ions may move (e.g., via Brownian motion) through static (e.g., non-flowing) saline water. When the sodium and chloride ions encounter surfaces of the iron nanoparticles in the desalination tank 700, the sodium and chloride ions can become adsorbed onto the surfaces of the surfaces of the iron nanoparticles. Thus, the saline water may become gradually desalinated even when it is held statically in contact with the desalination tank 700 via diffusion.

[0153] FIG. 8 illustrates a first view of an example desalination system 800 including multiple example desalination tanks. FIG. 9 illustrates a second view of the example desalination system 800 including multiple desalination tanks.

[0154] For example, the desalination system 800 may include ten desalination tanks (e.g., ten instances of the desalination tank 600) connected in series and / or parallel. In various cases, the desalination system 800 includes two fluid circuits, each including five desalination tanks connected to one another in series. The two fluid circuits may be connected to one another in parallel. In various cases, each fluid circuit includes a settling tank connected to the last desalination tank in the series. A recycling pipe 802 selectively connects the settling tank to the first desalination tank in the series. For instance, a valve may be coupled to, or included in, the recycling pipe 802 that selectively enables water to be cycled through the fluid circuit. In some cases, the valve opens if a salinity of the water in the settling tank exceeds a threshold

[0155] Multiple slurry pipes 804 are configured to output desalination media into the respective desalination tanks of the desalination system 800. Further, an air pipe 806 is configured to output air into a base of each of the desalination tanks in the desalination system 800. Saline water enters each fluid circuit of the desalination system 800, for instance, via an inflow pipe system 808. The inflow pipe system 808, for instance, splits into to two pipes that are respectively coupled to inlets of the first desalination tanks in each fluid circuit.

[0156] FIG. 10 illustrates a front view of the desalination system 800. Specifically, FIG. 10 illustrates a pair of desalination tanks that can be arranged in a side-by-side fashion in the example desalination system 800. For example, the pair of desalination tanks may represent the two first desalination tanks in the desalination system 800.

[0157] FIG. 11 illustrates a side view of the example desalination system 800 including multiple desalination tanks.

[0158] FIG. 12 illustrates various views of a settling tank 1200 of an example desalination system, such as the desalination system 800. The settling tank 1200, for instance, may be the final tank in a fluid circuit including a series of multiple desalination tanks In some cases, the settling tank 1200 includes a magnet configured to capture ironbased desalination media. In some cases, water output from the settling tank 1200 is optionally filtered before being output from the desalination system.

[0159] FIG. 13 illustrates at least one example device 1300 configured to enable and / or perform various functionality discussed herein. Further, the device(s) 1300 can be implemented as one or more server computers, a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, such as a cloud infrastructure, and the like. It is to be understood in the context of this disclosure that the device(s) 1300 can be implemented as a single device or as a plurality of devices with components and data distributed among them.

[0160] As illustrated, the device(s) 1300 include a memory 1304. In various embodiments, the memory 1304 is volatile (including a component such as Random Access Memory (RAM)), non-volatile (including a component such as Read Only Memory (ROM), flash memory, etc.) or some combination of the two.

[0161] The memory 1304 may include various components, such as instructions for executing various functions of the desalination controller 306. The memory 1304 can store methods, threads, processes, applications, or any other sort of executable instructions. The memory 1304 can also store files and / or databases.

[0162] The memory 1304 may include various instructions (e.g., instructions of the desalination controller 306), which can be executed by at least one processor 1306 to perform operations. In some embodiments, the processor(s) 1306 includes a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or both CPU and GPU, or other processing unit or component known in the art.

[0163] The device(s) 1300 can also include additional data storage devices (removable and / or non-removable) such as, for example, magnetic disks, optical disks, or tape. Such additional storage is illustrated in FIG. 13 by removable storage 1308 and non-removable storage 1310. Tangible computer-readable media can include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. The memory 1304, removable storage 1308, and non-removable storage 1310 are all examples of computer-readable storage media Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Discs (DVDs), Content-Addressable Memory (CAM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the device(s) 1300. Any such tangible computer-readable media can be part of the device(s) 1300.

[0164] The device(s) 1300 also can include input device(s) 1312, such as a keypad, a cursor control, a touch- sensitive display, voice input device, one or more sensors, and the like. In various cases, the device(s) 1300 include output device(s) 1314 such as a display, speakers, printers, one or more active elements (e.g., pumps, valves, heaters, etc.), and the like. In particular implementations, a user can provide input to the device(s) 1300 via a user interface associated with the input device(s) 1312 and / or the output device(s) 1314.

[0165] As illustrated in FIG. 13, the device(s) 1300 can also include one or more wired or wireless transceiver(s) 1316. For example, the transceiver(s) 1316 can include a Network Interface Card (NIC), a network adapter, a LAN adapter, or a physical, virtual, or logical address to connect to the various base stations or networks contemplated herein, for example, or the various user devices and servers. To increase throughput when exchanging wireless data, the transceiver(s) 1316 can utilize Multiple-Input / Multiple-Output (MIMO) technology. The transceiver(s) 1316 can include any sort of wireless transceivers capable of engaging in wireless, Radio Frequency (RF) communication. The transceiver(s) 1316 can also include other wireless modems, such as a modem for engaging in Wi-Fi, WiMAX, Bluetooth, or infrared communication. In some implementations, the transceiver(s) 1316 can be used to communicate between various functions, components, modules, or the like, that are included in the device(s) 1300.EXAMPLE CLAUSES

[0166] Various implementations of the present disclosure include:1. A desalination system, including: one or more sulfate reduction cells configured to lower a sulfate concentration in water to produce reduced sulfate water; a first desalination tank configured to: receive an inflow of the reduced sulfate water from the sulfate reduction cell, the inflow of reduced sulfate water including chloride ions and sodium ions; produce desalinated water by causing the reduced sulfate water to contact desalination media such that at least a portion of the chloride ions and at least a portion of the sodium ions are retained by the desalination media, and discharge the desalinated water; and a second desalination tank configured to receive the desalinated water from the first desalination tank.2. The desalination system of clause 1 , wherein the one or more sulfate reduction cells includes at least one biological sulfate reduction cell.3. The desalination system of clause 2, wherein the at least one biological sulfate reduction cell contains biological growth media, and wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the biological growth media.4. The desalination system of clause 3, wherein the biological growth media includes granular activated carbon or biochar.5. The desalination system of any of clauses 2 to 4, wherein the at least one biological sulfate reduction cell contains sulfide capture media, and wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the sulfide capture media.6. The desalination system of clause 5, wherein the sulfide capture media includes spent iron or biochar.7. The desalination system of any of clauses 2 to 6, further including: a carbon source feed unit configured to feed a carbon source to the at least one biological sulfate reduction cell.8. The desalination system of clause 7, wherein the carbon source is ethanol9. The desalination system of any of clauses 2 to 8, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 2000 mg / L sulfate to less than 500 mg / L sulfate.10. The desalination system of any of clauses 2 to 9, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 4000 mg / L sulfate to less than 1000 mg / L sulfate.11. The desalination system of any of clauses 2 to 10, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 4000 mg / L sulfate to less than 500 mg / L sulfate.12. The desalination system of any of clauses 2 to 11 , wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water by approximately 75% or more.13. The desalination system of any of clauses 2 to 13, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water by approximately 90% or more.14. The desalination system of clause 1 , wherein the one or more sulfate reduction cells includes multiple biological sulfate reduction cells configured to lower the sulfate concentration of the water by 75% or more.15. The desalination system of clause 1 , wherein the one or more sulfate reduction cells includes multiple biological sulfate reduction cells configured to lower the sulfate concentration of the water by 90% or more.16. The desalination system of clause 15, wherein the water flows through the multiple biological sulfate reduction cells in series.17. The desalination system of clause 16, wherein a first biological sulfate reduction cell of the multiple biological sulfate reduction cells lowers the sulfate concentration in the water, and wherein a second biological sulfate reduction cell of the multiple biological sulfate reduction cells further lowers the sulfate concentration in the water.18. The desalination system of clause 1 , further including: an aeration unit configured to: receive an inflow of the reduced sulfate water from the one or more sulfate reduction cells; and aerate the reduced sulfate water.19. The desalination system of clause 18, wherein the aeration unit is configured to aerate the reduced sulfate water by contacting the reduced sulfate water with oxygen gas.20. The desalination system of clause 19, wherein the oxygen gas includes air bubbles.21. The desalination system of clause 1 , wherein the desalination media includes an iron-based media.22. The desalination system of clause 1 , wherein the desalination media includes zero-valent iron.23. The desalination system of clause 1 , wherein the desalination media includes iron nanoparticles.24. The desalination system of clause 23, wherein the desalination media is introduced to the first desalination tank as a slurry.25. The desalination system of clause 24, wherein the inflow of the reduced sulfate water and the slurry are received at an inlet of the first desalination tank and the desalinated water is discharged at an outlet of the first desalination tank, the inlet being located at a higher altitude than the outlet.26. The desalination system of clause 1 , wherein the desalination system is configured to lower the sulfate concentration of the water by 75% or more, and wherein the desalination system is configured to desalinate the reduced sulfate water by 30% or more.27. The desalination system of clause 1 , wherein the desalination system is configured to lower the sulfate concentration of the water by 90% or more, and wherein the desalination system is configured to desalinate the reduced sulfate water by 50% or more.28. A desalination method, including: receiving, at a sulfate reduction cell, an inflow of water including sulfate anions, chlorine atoms, and sodium atoms; decreasing the sulfate anions in the water by passing the water through the sulfate reduction cell; directing the water from the sulfate reduction cell to a desalination tank; capturing, by a desalination media in the desalination tank, at least some of the chlorine atoms and the sodium atoms; and emitting an outflow of the water from the desalination tank.29. The desalination method of clause 28, wherein the sulfate reduction cell is a biological sulfate reduction cell.30. The desalination method of clause 29, wherein the biological sulfate reduction cell contains biological growth media, and wherein the biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the biological growth media.31. The desalination method of clause 30, wherein the biological growth media includes granulated activated carbon or biochar.32. The desalination method of any of clauses 29 to 31, further including: feeding a carbon source to the biological sulfate reduction cell.33. The desalination method of clause 32, wherein the carbon source includes ethanol.34. The desalination method of clause 28, further including: lowering a concentration of the sulfate in the water from over 2000 mg / L sulfate to less than 500 mg / L sulfate.35. The desalination method of clause 28, further including: lowering a concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 1000 mg / L sulfate.36. The desalination method of clause 28, further including: lowering a concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 500 mg / L sulfate.37. The desalination method of clause 28, further including: lowering a concentration of the sulfate in the water by approximately 75% or more.38. The desalination method of clause 28, further including: lowering a concentration of the sulfate in the water by approximately 90% or more.39. The desalination method of clause 28, further including: further decreasing the sulfate anions in the water by passing the water through an additional sulfate reduction cell.40. The desalination method of clause 28, further including: directing the water from the sulfate reduction cell to an aeration unit before directing the water to the desalination tank.41. The desalination method of clause 40, wherein the aeration unit is configured to aerate the water from the sulfate reduction cell.42. The desalination method of clause 41, wherein the aeration unit is configured to aerate the water from the sulfate reduction cell by causing the water to contact an oxygen gas.43. The desalination method of any of clauses 40 to 42, wherein the aeration unit is configured to aerate the water from the sulfate reduction cell by causing the water to contact air bubbles.44. The desalination system of clause 28, wherein the desalination media includes an iron-based media45. The desalination system of clause 28, wherein the desalination media includes zero-valent iron.46. The desalination system of clause 28, wherein the desalination media includes a plurality of iron nanoparticles.47. The desalination system of clause 46, wherein the desalination media is introduced to the desalination tank as a slurry.48. The desalination method of clause 28, further including: capturing additional chlorine atoms and additional sodium atoms by passing the water through an additional desalination tank.49. The desalination method of clause 28, wherein the inflow of the water has a first Total Dissolved Solids (TDS) level and the outflow of the water has a second TDS level, the second TDS level being one half or less of the first TDS levelCONCLUSION

[0167] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be used for realizing implementations of the disclosure in diverse forms thereof.

[0168] As will be understood by one of ordinary skill in the art, each implementation disclosed herein can comprise, consist essentially of or consist of its particular stated element, step, or component. Thus, the terms “include” or “including” should be interpreted to recite: “comprise, consist of, or consist essentially of ” The transition term “comprise” or “comprises” means has, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts The transitional phrase “consisting of” excludes any element, step, ingredient or component not specified. The transition phrase “consisting essentially of” limits the scope of the implementation to the specified elements, steps, ingredients or components and to those that do not materially affect the implementation. As used herein, the term “based on” is equivalent to “based at least partly on,” unless otherwise specified.

[0169] Unless otherwise indicated, all numbers expressing quantities, properties, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. When further clarity is required, the term “about” has the meaning reasonably ascribed to it by a person skilled in the art when used in conjunction with a stated numerical value or range, i.e. denoting somewhat more or somewhat less than the stated value or range, to within a range of ±20% of the stated value; ±19% of the stated value; ±18% of the stated value; ±17% of the stated value; ±16% of the stated value; ±15% of the stated value; ±14% of the stated value; ±13% of the stated value; ±12% of the stated value; ±11 % of the stated value; ±10% of the stated value; ±9% of the stated value; ±8% of the stated value; ±7% of the stated value; ±6% of the stated value; ±5% of the stated value; ±4% of the stated value; ±3% of the stated value; ±2% of the stated value; or ±1 % of the stated value.

[0170] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0171] The terms “a,” “an,” “the” and similar referents used in the context of describing implementations (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate implementations of the disclosure and does not pose a limitation on the scope of the disclosure. No language in the specification should be construed as indicating any non-claimed element essential to the practice of implementations of the disclosure

[0172] Groupings of alternative elements or implementations disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Claims

CLAIMSWHAT IS CLAIMED IS:1 . A desalination system, comprising: one or more sulfate reduction cells configured to lower a sulfate concentration in water to produce reduced sulfate water; a first desalination tank configured to: receive an inflow of the reduced sulfate water from the sulfate reduction cell, the inflow of reduced sulfate water including chloride ions and sodium ions; produce desalinated water by causing the reduced sulfate water to contact desalination media such that at least a portion of the chloride ions and at least a portion of the sodium ions are retained by the desalination media, and discharge the desalinated water; and a second desalination tank configured to receive the desalinated water from the first desalination tank.

2. The desalination system of claim 1 , wherein the one or more sulfate reduction cells includes at least one biological sulfate reduction cell.

3. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell contains biological growth media, and wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the biological growth media.

4. The desalination system of claim 3, wherein the biological growth media comprises granular activated carbon or biochar.

5. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell contains sulfide capture media, and wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the sulfide capture media.

6. The desalination system of claim 5, wherein the sulfide capture media comprises spent iron or biochar.

7. The desalination system of claim 2, further comprising: a carbon source feed unit configured to feed a carbon source to the at least one biological sulfate reduction cell.

8. The desalination system of claim 7, wherein the carbon source is ethanol.

9. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 2000 mg / L sulfate to less than 500 mg / L sulfate.

10. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 4000 mg / L sulfate to less than 1000 mg / L sulfate.

11. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water from over 4000 mg / L sulfate to less than 500 mg / L sulfate.

12. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water by approximately 75% or more.

13. The desalination system of claim 2, wherein the at least one biological sulfate reduction cell is configured to lower the sulfate concentration of the water by approximately 90% or more.

14. The desalination system of claim 1 , wherein the one or more sulfate reduction cells comprises multiple biological sulfate reduction cells configured to lower the sulfate concentration of the water by 75% or more.

15. The desalination system of claim 1 , wherein the one or more sulfate reduction cells comprises multiple biological sulfate reduction cells configured to lower the sulfate concentration of the water by 90% or more.

16. The desalination system of claim 15, wherein the water flows through the multiple biological sulfate reduction cells in series.

17. The desalination system of claim 16, wherein a first biological sulfate reduction cell of the multiple biological sulfate reduction cells lowers the sulfate concentration in the water, and wherein a second biological sulfate reduction cell of the multiple biological sulfate reduction cells further lowers the sulfate concentration in the water.

18. The desalination system of claim 1 , further comprising: an aeration unit configured to: receive an inflow of the reduced sulfate water from the one or more sulfate reduction cells; and aerate the reduced sulfate water.

19. The desalination system of claim 18, wherein the aeration unit is configured to aerate the reduced sulfate water by contacting the reduced sulfate water with oxygen gas.

20. The desalination system of claim 19, wherein the oxygen gas comprises air bubbles.21 . The desalination system of claim 1 , wherein the desalination media comprises an iron-based media.

22. The desalination system of claim 1 , wherein the desalination media comprises zero-valent iron.

23. The desalination system of claim 1 , wherein the desalination media comprises iron nanoparticles.

24. The desalination system of claim 23, wherein the desalination media is introduced to the first desalination tank as a slurry.

25. The desalination system of claim 24, wherein the inflow of the reduced sulfate water and the slurry are received at an inlet of the first desalination tank and the desalinated water is discharged at an outlet of the first desalination tank, the inlet being located at a higher altitude than the outlet.

26. The desalination system of claim 1 , wherein the desalination system is configured to lower the sulfate concentration of the water by 75% or more, and wherein the desalination system is configured to desalinate the reduced sulfate water by 30% or more.

27. The desalination system of claim 1 , wherein the desalination system is configured to lower the sulfate concentration of the water by 90% or more, and wherein the desalination system is configured to desalinate the reduced sulfate water by 50% or more.

28. A desalination method, comprising: receiving, at a sulfate reduction cell, an inflow of water comprising sulfate anions, chlorine atoms, and sodium atoms; decreasing the sulfate anions in the water by passing the water through the sulfate reduction cell; directing the water from the sulfate reduction cell to a desalination tank;capturing, by a desalination media in the desalination tank, at least some of the chlorine atoms and the sodium atoms; and emitting an outflow of the water from the desalination tank29. The desalination method of claim 28, wherein the sulfate reduction cell is a biological sulfate reduction cell.

30. The desalination method of claim 29, wherein the biological sulfate reduction cell contains biological growth media, and wherein the biological sulfate reduction cell is configured to lower the sulfate concentration in the water by passing the water through the biological growth media.

31. The desalination method of claim 30, wherein the biological growth media comprises granulated activated carbon or biochar.

32. The desalination method of claim 29, further comprising: feeding a carbon source to the biological sulfate reduction cell.

33. The desalination method of claim 32, wherein the carbon source comprises ethanol.

34. The desalination method of claim 28, further comprising: lowering a concentration of the sulfate in the water from over 2000 mg / L sulfate to less than 500 mg / L sulfate.

35. The desalination method of claim 28, further comprising: lowering a concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 1000 mg / L sulfate.

36. The desalination method of claim 28, further comprising: lowering a concentration of the sulfate in the water from over 4000 mg / L sulfate to less than 500 mg / L sulfate.

37. The desalination method of claim 28, further comprising: lowering a concentration of the sulfate in the water by approximately 75% or more.

38. The desalination method of claim 28, further comprising: lowering a concentration of the sulfate in the water by approximately 90% or more.

39. The desalination method of claim 28, further comprising: further decreasing the sulfate anions in the water by passing the water through an additional sulfate reduction cell40. The desalination method of claim 28, further comprising: directing the water from the sulfate reduction cell to an aeration unit before directing the water to the desalination tank.41 . The desalination method of claim 40, wherein the aeration unit is configured to aerate the water from the sulfate reduction cell.

42. The desalination method of claim 41 , wherein the aeration unit is configured to aerate the water from the sulfate reduction cell by causing the water to contact an oxygen gas.

43. The desalination method of claim 41 , wherein the aeration unit is configured to aerate the water from the sulfate reduction cell by causing the water to contact air bubbles.

44. The desalination system of claim 28, wherein the desalination media comprises an iron-based media.

45. The desalination system of claim 28, wherein the desalination media comprises zero-valent iron.

46. The desalination system of claim 28, wherein the desalination media comprises a plurality of iron nanoparticles.

47. The desalination system of claim 46, wherein the desalination media is introduced to the desalination tank as a slurry.

48. The desalination method of claim 28, further comprising: capturing additional chlorine atoms and additional sodium atoms by passing the water through an additional desalination tank.

49. The desalination method of claim 28, wherein the inflow of the water has a first Total Dissolved Solids (TDS) level and the outflow of the water has a second TDS level, the second TDS level being one half or less of the first TDS level

Images