System and method for recovery of ammonia from an aqueous solution

Abstract

A system for treating an aqueous solution is disclosed. The system includes a plurality of modules arranged in series, including a lead module having a shell inlet fluidly connected to a source of an aqueous solution having ammonia, a shell outlet, a lumen inlet fluidly connected to a source of a first acidic solution, and a lumen outlet, and an end module having a lumen inlet fluidly connected to a source of a second acidic solution, a lumen outlet, a shell inlet, and a shell outlet, the shell outlet of the lead module is fluidly connected to the shell inlet of the end module, the first acidic solution has a higher pH than the second acidic solution. Methods of treating an aqueous solution having ammonia with the system are also disclosed.

Description

[0001] Docket No. 202488138PPCT01

[0002] SYSTEM AND METHOD FOR RECOVERY OF AMMONIA FROM AN AQUEOUS

[0003] SOLUTION

[0004] CROSS-REFERENCE TO RELATED APPLICATIONS

[0005] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Serial No. 63 / 717.503 titled “OPTIMIZATION OF MEMBRANE CONTACTOR SYSTEMS FOR AMMONIA REMOVAL AND RECOVERY” filed November 7, 2024, which is incorporated herein by reference in its entirety for all purposes.

[0006] FIELD OF TECHNOLOGY

[0007] Aspects and embodiments disclosed herein are generally related to systems and methods for recover}' of ammonia, and more specifically, to systems and methods using gas permeable membrane contactors for recovery of ammonia from wastewater.

[0008] SUMMARY

[0009] In accordance with one aspect, there is provided a system for treating an aqueous solution. The system may comprise a plurality of modules arranged in series, each module comprising a plural ity of membranes, each membrane having a lumen side and a shell side, the plurality of modules comprising a lead module having a shell inlet fluidly connected to a source of the aqueous solution comprising ammonia, a shell outlet, a lumen inlet fluidly connected to a source of a first acidic solution, and a lumen outlet, the plurality of modules comprising an end module having a lumen inlet fluidly connected to a source of a second acidic solution, a lumen outlet, a shell inlet, and a shell outlet, the shell outlet of the lead module being fluidly connected to the shell inlet of the end module, the first acidic solution having a higher pH than the second acidic solution.

[0010] In some embodiments, the lumen outlet of the lead module is fluidly connected to a first reservoir comprising the first acidic solution by a first return conduit.

[0011] In some embodiments, the lumen outlet of the end module is fluidly connected to a second reservoir comprising the second acidic solution by a second return conduit.

[0012] In some embodiments, the first acidic solution has a higher concentration of ammonium sulfate than the second acidic solution.

[0013] In some embodiments, the concentration of ammonium sulfate in the first acidic solution is between 20% w / w and 40% w / w. Docket No. 202488138PPCT01

[0014] In some embodiments, the source of the second acidic solution is fluidly connected to the source of the first acidic solution.

[0015] In some embodiments, the system may further comprise at least one intermediate module having a shell inlet, a shell outlet, a lumen inlet, and a lumen outlet, the shell inlet of the intermediate module being fluidly connected to the shell outlet of the lead module, the shell outlet of the intermediate module being fluidly connected to the shell inlet of the end module, the lumen inlet of the intermediate module being fluidly connected to the source of the second acidic solution, and the lumen outlet of the intermediate module being fluidly connected to the lumen inlet of the end module.

[0016] In some embodiments, the first acidic solution has a pH between about 2.0 and 5.4 and the second acidic solution has a pH of 3.5 or less.

[0017] In some embodiments, the system may further comprise a flow control subsystem configured to control flow rate of the aqueous solution and the first acidic solution, wherein a ratio of the flow rate of the first acidic solution to the flow rate of the aqueous solution through the lead module is between about 3.5 and 4 to 1.

[0018] In some embodiments, a temperature of the first acidic solution is higher than a temperature of the aqueous solution.

[0019] In some embodiments, the temperature of the first acidic solution is between 3°F and 9°F higher than the temperature of the aqueous solution.

[0020] In some embodiments, the lumen outlet of the lead module is fluidly connected to a product reservoir.

[0021] In some embodiments, the system is configured to maintain the aqueous solution at a temperature between approximately 95°F and 150°F to enhance ammonia volatility.

[0022] In some embodiments, the system is configured to maintain the aqueous solution at a temperature between approximately 95°F and 150°F to enhance ammonia volatility.

[0023] In some embodiments, the system further includes a heating subsystem configured to heat the aqueous solution and the acidic solution to the respective temperatures.

[0024] In some embodiments, the system further includes a pre-heat exchanger configured to pre-heat the aqueous solution comprising ammonia.

[0025] In some embodiments, at least one of the plurality of modules includes one or more high-temperature resistant membranes capable of withstanding temperatures of at least 150°F.

[0026] In some embodiments, the at least one of the plurality of modules further includes one or more membrane mounting materials capable of withstanding temperatures of at least 150°F. Docket No. 202488138PPCT01

[0027] In accordance w ith another aspect, there is provided a method of treating an aqueous solution comprising ammonia with a system comprising a plurality of modules, each module comprising a plurality of membranes, each membrane having a lumen side and a shell side. The method may comprise directing the aqueous solution comprising ammonia to a shell inlet of a lead module to produce a first effluent, the first effluent being fluidly connected to a shell inlet of an end module, directing a first acidic solution to a lumen inlet of the lead module, at least a portion of the ammonia in the aqueous solution being diffused through the plurality of membranes of the lead module to produce a product comprising ammonium, directing a second acidic solution to a lumen inlet of the end module, at least a portion of the ammonia in the first effluent being diffused through the plurality of membranes of the end module to produce a first intermediate product comprising ammonium and a second effluent, the first acidic solution having a higher pH than the second acidic solution.

[0028] In some embodiments, the method may further comprise controlling pH of the first acidic solution to be between about 2.0 and 5.4 and controlling pH of the second acidic solution to be 3.5 or less.

[0029] In some embodiments, the method may further comprise controlling a temperature of the first acidic solution to be higher than a temperature of the aqueous solution.

[0030] In some embodiments, the method may further comprise controlling the temperature of the first acidic solution to be betw een 3°F and 9°F higher than the temperature of the aqueous solution.

[0031] In some embodiments, the temperature of the aqueous solution is between 95°F and 150°F.

[0032] In some embodiments, the method may further comprise controlling flow rate of the aqueous solution and the first acidic solution, wherein a ratio of the flow rate of the first acidic solution to the flow rate of the aqueous solution through the lead module is betw een about 3.5 and 4 to 1.

[0033] In some embodiments, the method may further comprise controlling a concentration of ammonium sulfate in the first acidic solution to be higher than a concentration of ammonium sulfate in the second acidic solution, the concentration of ammonium sulfate in the first acidic solution being controlled to be between 20% w / w and 40% w / w.

[0034] In some embodiments, the method may further comprise directing at least a portion of the product to a reservoir comprising the first acidic solution.

[0035] In some embodiments, the method may further comprise directing at least a portion of the first intermediate product to a reservoir comprising the second acidic solution. Docket No. 202488138PPCT01

[0036] In some embodiments, the method may further comprise directing at least a portion of the second acidic solution to the reservoir comprising the first acidic solution.

[0037] In accordance with another aspect, there is provided a method of facilitating recovery of ammonia from an aqueous solution. The method may comprise providing instructions to fluidly connect a shell inlet of a lead module having a plurality of membranes, each membrane having a lumen side and a shell side, to a source of an aqueous solution comprising ammonium, providing instructions to fluidly connect a lumen outlet of the lead module to a lumen inlet of an end module having a plurality’ of membranes, each membrane having a lumen side and a shell side, providing instructions to fluidly connect a lumen inlet of the lead module to a source of a first acidic solution and fluidly connect a lumen outlet of the lead module back to the source of the first acidic solution, and providing instructions to fluidly connect a lumen inlet of the end module to a source of a second acidic solution and fluidly connect a lumen outlet of the end module back to the source of the second acidic solution, the first acidic solution having a higher pH than the second acidic solution.

[0038] In some embodiments, the method may further comprise providing instructions to fluidly connect the source of the second acidic solution to the source of the first acidic solution.

[0039] In some embodiments, the method may further comprise providing instructions to fluidly connect the lumen outlet of the lead module to a product reservoir.

[0040] In accordance with another aspect, there is provided a method of retrofitting a system for recovery of ammonia from an aqueous solution comprising an end module having a plurality of membranes, each membrane having a lumen side and a shell side. The method may comprise providing a lead module having a plurality of membranes, each membrane having a lumen side and a shell side, fluidly connecting a source of the aqueous solution to a shell inlet of the lead module, fluidly connecting a shell outlet of the lead module to a shell inlet of the end module, fluidly connecting a source of a first acidic solution to a lumen inlet of the lead module, and fluidly connecting a lumen outlet of the lead module back to the source of the first acidic solution, a source of a second acidic solution being fluidly connected to a lumen inlet of the end module, and a lumen outlet of the end module being fluidly connected back to the source of the second acidic solution, the first acidic solution having a higher pH than the second acidic solution.

[0041] In some embodiments, the method may further comprise fluidly connecting the source of the second acidic solution to the source of the first acidic solution. Docket No. 202488138PPCT01

[0042] In some embodiments, the method may further comprise fluidly connecting the lumen outlet of the lead module to a product reservoir.

[0043] In accordance with another aspect, a method of treating an aqueous solution comprising ammonia with a system comprising at least one module, the at least one module comprising at least one membrane, and the at least one membrane having a lumen side and a shell side is disclosed. The method includes heating the aqueous solution comprising ammonia to a temperature between approximately 95°F and 150°, directing the aqueous solution comprising ammonia to a shell inlet of the at least one module to produce an effluent, heating an acidic solution to a temperature between approximately 3°F and 9°F higher than the aqueous solution, and directing the acidic solution to a lumen inlet of the at least one module, at least a portion of the ammonia in the aqueous solution being diffused through the at least one membrane of the at least one module to produce a product comprising ammonium.

[0044] In some embodiments, heating the aqueous solution and acidic solution increases ammonia volatility and improves diffusion efficiency across the at least one membrane.

[0045] The disclosure contemplates all combinations of any one or more of the foregoing aspects and / or embodiments, as well as combinations w ith any one or more of the embodiments set forth in the detailed description and any examples.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0048] FIG. 1 a box diagram of a system for removing ammonia from an aqueous solution, according to one embodiment;

[0049] FIG. 2 is a box diagram of an alternate system for removing ammonia from an aqueous solution, according to one embodiment;

[0050] FIG. 3 is a box diagram of an alternate system for removing ammonia from an aqueous solution, according to one embodiment;

[0051] FIG. 4 is a box diagram of an alternate system for removing ammonia from an aqueous solution, according to one embodiment;

[0052] FIG. 5 is a schematic diagram of a system for removing ammonia from an aqueous solution, according to one embodiment; Docket No. 202488138PPCT01

[0053] FIG. 6 is a graph showing percent ammonia removal from an aqueous solution, according to one embodiment;

[0054] FIG. 7 is a graph showing percent ammonia removal from an aqueous solution, according to one embodiment;

[0055] FIG. 8 is a graph showing percent ammonia removal from an aqueous solution, according to one embodiment;

[0056] FIG. 9 is a box diagram of an alternate system for removing ammonia from an aqueous solution, according to one embodiment;

[0057] FIG. 10 is a box diagram of an alternate system for removing ammonia from an aqueous solution, according to one embodiment;

[0058] FIG. 11 is a graph showing Henry’s Solubility Constant for ammonia, carbon dioxide, and hydrogen sulfide vs. temperature; and

[0059] FIG. 12 is a graph showing Henry’s Volatility Constant for ammonia vs. temperature.

[0060] DETAILED DESCRIPTION

[0061] The systems and methods disclosed herein may be used to treat aqueous solutions, for example, wastewaters, having ammonia to produce an effluent suitable for secondary use or discharge to the environment. In particular, the systems and methods disclosed herein may be employed to reduce a concentration of nitrogen-containing compounds, such as ammonia, from aqueous solutions. In accordance with certain embodiments, the systems and methods disclosed herein may promote removal of nitrogen-containing compounds from aqueous solutions by gas transfer, such as with a gas permeable membrane contactor. The systems and methods disclosed herein may promote recovery of nitrogen-containing compounds in an acidic solution.

[0062] Gas transfer generally involves contact of the aqueous solution with a membrane configured to enable gas-liquid separation by being permeable to gases and impermeable to liquids. For instance, flowing an aqueous solution inside a gas transfer membrane may selectively pass dissolved gases, leaving substantially pure solvents on the filtrate side. The dissolved gas may be absorbed from a feed stream into an acid stream.

[0063] Gas permeable membrane contactors may be used to remove dissolved gases from compatible liquid streams without dispersion. A membrane contactor, also referred to as a “module’’ herein, may be designed to contain a plurality of microporous hollow fibers placed inside a contactor housing. The hollow fibers may define a lumen side and a shell or housing side. The membranes may be arranged with substantially uniform spacing to allow for high Docket No. 202488138PPCT01 flow capacity and utilization of the total membrane surface area. Unlike dispersed-phase contactors, such as packed columns, membrane contactors may provide a constant interfacial area for transfer over the entire range of flow rates.

[0064] In certain embodiments, the membranes may be formed of a microporous hydrophobic material. Utilizing a hy drophobic membrane may prevent aqueous liquids from penetrating the membrane pores. One exemplary- gas transfer membrane module is the Liqui- Cel™ Membrane contactor (distributed by 3M™. Maplewood, MN).

[0065] Systems and methods for treating an aqueous solution to reduce ammonia concentration are disclosed herein. Reducing ammonia concentration may include removing any amount of ammonia from the aqueous stream. Thus, in some embodiments, ammonia concentration may be reduced by at least 10%, for example, at least 25%. at least 50%. at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0066] Systems and methods for recovery of ammonia are disclosed herein. Recovery- of ammonia may include transferring nitrogen-containing compounds from an aqueous solution into an acidic solution. Rate of recovery of ammonia, as used herein, may refer to a rate of transfer of nitrogen-containing compounds. In some embodiments, at least 10% of ammonia may be recovered from the aqueous solution, for example, at least 25%, at least 50%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0067] The methods may include directing the aqueous solution comprising ammonia to a module comprising a plurality of membranes, each membrane having a shell side and a lumen side. The aqueous solution may be directed to a shell inlet of the module. An acidic solution may be directed to a lumen inlet of the module. The lumen inlet and shell inlet may be positioned on opposite ends of the module. Thus, in operation, the aqueous solution and acidic solution may run countercurrent to each other through the module. As the aqueous solution flows along the shell side of the membranes, ammonia is generally diffused through the membrane into the acidic solution traveling in a countercurrent direction through the lumen.

[0068] The reaction may produce an effluent having reduced ammonia, which is discharged through the shell outlet of the module and an intermediate product comprising ammonium, which is discharged through the lumen outlet of the module. The lumen outlet and shell outlet may also be positioned on opposite ends of the module, each outlet positioned across from a respective inlet. Docket No. 202488138PPCT01

[0069] The membrane may be formed of a hydrophobic material. In some embodiments, the membrane may be formed of a hydrophobic polymeric material or combination of hydrophobic polymeric materials. Exemplary hydrophobic polymeric materials include polypropylene, polyethylene, polystyrene, polyvinylchloride, polytetrafluorethylene, poly dimethylsiloxane, polyester, and polyurethane.

[0070] The membrane and / or module may be operable at high temperatures. In some embodiments, the membrane and / or module may be operable at a temperature of 95°F (35°C) or higher, for example, 95°F (35°C) - 150°F (65.55°C) or 158°F (70°C). Thus, in some embodiments, the membrane and / or module may also be operable at a temperature of 120°F (48.89°C) - 150°F (65.55°C) or alternatively 122°F (50°F) - 158°F (70°C).

[0071] The acidic solution may refer to any proton donor capable of ionizing ammonia. In certain exemplary embodiments, the acidic solution may comprise sulfuric acid (H2SO4), which dissociates into hydrogen ions (2H+) and sulfate ions (SC>42'). The hydrogen ions may react with ammonia (NFFig)) transferred through the membrane to produce ammonium (NH4+). In this exemplary embodiment, the ammonium reacts with the sulfate ions to produce ammonium sulfate (NFU SC Thus, in some embodiments, the intermediate product may comprise ammonium in the form of ammonium sulfate. In some embodiments, pH of the acidic solution may be controlled to prevent redissolution of the gas into a liquid. Un-ionized gas may cross the membrane and become a soluble ion in the acidic solution, preventing redissolution into the aqueous solution. Furthermore, pH of the acidic solution may be controlled to optimize efficiency of the acidic solution. The pH of the acidic solution may be controlled to be below about 5.4, below about 4, or below about 3.5, for example, between about 2 and 3, between about 2 and 3.5, between about 2 and 4, between about 2 and 5.4, between about 3 and 5.4. between about 3.5 and 5.4, between about 4 and 5.4, between about 5 and 5.4, or about 2, about 3, about 3.5, about 4, about 4.5, about 5, or about 5.4. In some embodiments, pH of the acidic solution may be controlled to prevent or inhibit the production of hydrogen ions (H+). The pH of the acidic solution may be controlled to be below about 2, for example, between about 1.5 and 2, for example, between about 1.5 and 1.75 or between about 1.75 and 2, about 1.5, about 1.65, about 1.7. about 1.75, about 1.8, about 1.85, about 1.9, or about 2.

[0072] While the disclosure relates to sulfuric acid as one exemplary acid for ammonia recovery, it should be understood that the methods and systems disclosed herein may utilize other acids for effective ammonia recovery. Exemplary acids which may be used instead of sulfuric acid include phosphoric acid, nitric acid, citric acid, and others. Thus, in certain Docket No. 202488138PPCT01 embodiments, the ammonium may react to produce ammonium phosphate, ammonium nitrate, ammonium citrate, or others, in the intermediate product. The target pH range may be selected responsive to the acid. For instance, the target pH range may correspond to a pH range for which the acid will efficiently re-ionize and absorb ammonia, or the target pH range may correspond to a pH range that will prevent or inhibit production of hydrogen ions, as previously described.

[0073] Furthermore, in some embodiments, temperature of the reaction, for example, temperature of the aqueous solution and / or acidic solution, may be controlled. For instance, temperature of the aqueous solution and / or acidic solution may be controlled to be above about 95°F (35°C), for example, between about 95°F (35°C) and 150°F (65.55°C) or 158°F (70°C), or between about 120°F (48.89°C) and 150°F (65.55°C) or alternatively between about 122°F (50°F) and 158°F (70°C). The elevated temperature may increase ammonia volatility, improving the efficiency of the reaction. However, the temperature may be selected to avoid volatilization of the ammonia.

[0074] In some embodiments, the temperature of the acidic solution may be controlled to be equal to or higher than the temperature of the aqueous solution. For instance, in some embodiments, the temperature of the acidic solution may be controlled to be equal to, or at least 1°F higher, or at least 0.5°C higher, than the temperature of the aqueous solution, for example, 0-l°F, 0-5°F, 3-6°F, 3-9°F, 4-6°F, 4-9°F, 5-10°F, 10-20°F higher or more, or 0- 0.55°C. 0-2.78°C, 1.67-3.33°C, 1.67-5°C, 2.22-3.33°C, 2.22-5°C, 2.78-5.55°C, 5.55-11. 11°C higher or more. Controlling the temperature differential between the acidic solution and the aqueous solution may improve efficiency of the ammonia recovery, for example, by preventing or inhibiting transfer of gas through the membrane in the opposite direction. Additionally, while not wishing to be bound by theory, it is believed that controlling the temperature differential may prevent condensation within the module, which is generally undesirable.

[0075] The effluent, produced from the aqueous solution after removal of ammonia, may be directed to a point of use. The point of use may be associated with an industrial, commercial, or consumer use. The point of use may be associated with microelectronics manufacturing, semiconductor manufacturing, food and beverage production, food processing (including agricultural uses and irrigation), power and steam generation (including nuclear power generation), oil and gas processing, textile manufacturing, paper manufacturing and recycling, pharmaceutical manufacturing, chemical processing, laboratory and analytical uses, inks and coatings, metal extraction systems or processes, and others. Docket No. 202488138PPCT01

[0076] In some embodiments, the method may be performed with a plurality of modules arranged in series. The aqueous solution may be directed to the shell inlet of a lead module in the series. The acidic solution, which generally runs countercurrent to the aqueous solution, may be directed to an end module in the series, the end module being positioned opposite or farthest from the lead module in the series. Optionally, one or more intermediate modules may be positioned in the series between the lead module and the end module.

[0077] As the aqueous solution is directed to the lead module, a portion of the ammonia in the aqueous solution may be diffused through the membranes and an effluent having a lower concentration of ammonia is generally produced which may be discharged through the shell outlet of the lead module. The effluent may then be directed to a shell inlet of a following module in the series. The effluent produced by each subsequent module having a lower concentration of ammonia may be directed to the shell inlet of each following module, until an effluent is directed to the shell inlet of the end module. The effluent produced in the end module and discharged through the shell outlet of the end module may be considered a treated solution.

[0078] Similarly, as the acidic solution is directed to the end module, an intermediate product having a higher concentration of ammonium is generally produced which may be discharged through the lumen outlet of the end module. At least a portion of the intermediate product (and optionally all of the intermediate product) may then be directed to a lumen inlet of a preceding module in the series. At least a portion of the intermediate product produced by each prior module may be directed to the lumen inlet of a preceding module, until a portion of the intermediate product is directed to the lumen inlet of the lead module. The product containing ammonium may then be discharged through the lumen outlet of the lead module. In certain embodiments, an optional acidic stream may be combined with the intermediate product at any point in the series.

[0079] In some embodiments, the lead module may be operable as a saturator. For instance, the system may be constructed and arranged to operate the lead module as a saturator. The aqueous solution may be directed to the shell inlet of the lead module. An effluent having a lower concentration of ammonia may be produced in the lead module, discharged through the shell outlet of the lead module, and directed to the shell inlet of the end module, as previously described. The effluent may be directed through one or more optional intermediate modules upstream from the end module, as previously described. A first acidic solution may be directed to the lumen inlet of the lead module to produce a product comprising ammonium. A Docket No. 202488138PPCT01 second acidic solution may be directed to the lumen inlet of the end module to produce an intermediate product.

[0080] Optionally, the second acidic solution may be directed to the lumen inlet of an intermediate module to produce an intermediate product. At least a portion of the intermediate product may be directed to the lumen inlet of a subsequent module, until a portion of the intermediate product is directed to the lumen inlet of the end module. Thus, the intermediate product may flow downstream in the series of modules.

[0081] In other embodiments, the intermediate product may flow upstream in the series of modules. The second acidic solution may be directed to the lumen inlet of the end module to produce an intermediate product. At least a portion of the intermediate product may be directed to the lumen inlet of a prior module, until a portion of the intermediate product is directed to the lumen inlet of an intermediate module that is positioned directly downstream from the lead module.

[0082] In certain exemplary embodiments, the first acidic solution may have a higher pH than the second acidic solution. The methods may comprise controlling pH of the first and / or second acidic solutions. The first acidic solution may have a pH between about 2 and 5.4, for example, between about 2 and 3, between about 2 and 3.5, between about 2 and 4, between about 3 and 5.4, between about 3.5 and 5.4, between about 4 and 5.4, between about 5 and 5.4, or about 2, about 3, about 3.5, about 4, about 4.5, about 5, or about 5.4. The second acidic solution may have a pH of 3.5 or less, for example, about 3.0 or less, about 2.5 or less, about 2.0 or less, or about 3.5, about 3.0, about 2.5, or about 2.

[0083] In certain embodiments, the first acidic solution may have a higher concentration of ammonium than the second acidic solution. Thus, the first acidic solution may be more concentrated than the second acidic solution. The first acidic solution may have a higher concentration of ammonium in the form of ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium citrate, or other ammonium compound. The first acidic solution may have a concentration up to 40% w7w of ammonium. The concentration of ammonium in the first acidic solution may be controlled to be between 20% w / w and 40% w / w, for example, between 20% w / w and 30% w / w or between 30% w / w and 40% w / w.

[0084] Thus, the second acidic solution may have a lower concentration of ammonium (e g., ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium citrate, or other ammonium compound) than the first acidic solution. The second acidic solution may be more dilute than the first acidic solution. In certain exemplary embodiments, the concentration of ammonium in the second acidic solution may be controlled to be less than 30% w / w Docket No. 202488138PPCT01 ammonium, for example, less than 25% w / w, or less than 20% w / w. The concentration of ammonium in the second acidic solution may be controlled to be between 10% w / w and 30% w / w, for example, between 10% w / w and 20% w / w, between 20% w / w and 25% w / w, or between 25% w / w and 30% w / w. In some embodiments, the concentration of ammonium in the second acidic solution may be greater than 30% w / w, as long as the second acidic solution is more dilute than the first acidic solution.

[0085] The concentration of ammonium in the acidic solution, e.g.. first or second acidic solution, may be controlled by directing at least a portion of the product or intermediate product back to the acidic solution. In certain embodiments, the first and second acidic solutions may be contained in respective reservoirs. Within their reservoirs, one or more properties of the acidic solution may be measured and / or controlled, such as pH, ammonium concentration, temperature, density, conductivity, etc. In certain embodiments, for example, as shown in the exemplary systems of FIGS. 9-10, a portion of the product may be directed back to a reservoir containing the first acidic solution while at least a portion of the intermediate product may be directed back to a reservoir containing the second acidic solution.

[0086] Optionally, at least a portion of the first acidic solution and / or second acidic solution may be directed to the opposite reservoir. For example, at least a portion of the first acidic solution may be directed to the reservoir containing the second acidic solution. In some embodiments, at least a portion of the second acidic solution may be directed to a reservoir containing the first acidic solution.

[0087] In some embodiments, the temperature of the first acidic solution may be higher than the temperature of the aqueous solution. The second acidic solution may have a temperature that is equal to or higher than the temperature of the aqueous solution and / or effluent.

[0088] By operating the lead module as a saturator and directing a first acidic solution having a higher pH and / or concentration of ammonium to the lumen inlet of the lead module, it is believed that the treatment of the aqueous solution and the production of an ammonium containing product is more efficient. Thus, the saturator may improve removal of the nitrogen-containing compounds from the aqueous solution and recovery of the nitrogencontaining compounds in the product.

[0089] Specifically, it is believed that operating the lead module as a saturator may enable the ability to obtain a higher concentration of ammonium in solution. Currently, testing indicates that there is a trade-off between maximum saturation and removal efficiency. The percent ammonia removal in the lead module as a saturator is generally lower and it may also Docket No. 202488138PPCT01 require more energy (e.g., due to viscosity / friction) than the other modules in the series. The downstream modules may generally have a higher percent removal of ammonia, but may not achieve as high of a concentration. Thus, by having more than one acidic solution throughout the system, the benefits of both high saturation and high removal efficiency may be achieved.

[0090] In certain exemplary embodiments, aqueous solutions treatable by the methods disclosed herein may comprise 300 ppm-8000 ppm NH3-N, for example, 300-500 ppm, 500- 1000 ppm, 1000-2000 ppm, 2000-4000 ppm, 4000-6000 ppm or 6000-8000 ppm. However, aqueous solutions having less than 300 ppm NH3-N may also be treatable by the methods disclosed herein. In certain exemplary7embodiments, for an aqueous solution comprising about 6000 ppm ammonia nitrogen (NH3-N), the effluent discharged from the end module may comprise 155 ppm or less NH3-N (200 mg / L NH4), for example. 1-100 mg / L NH4, 1-10 mg / L NH4, 1 -5 mg / L NH4, or about 1 mg / L NH4.

[0091] The effluent produced by the systems and methods described herein may have 80- 99% less NH3-N than the aqueous solution, for example, 80-85% less, 85-90% less, 90-95% less, 95-97% less, or 97-99% less NH3-N than the aqueous solution. The effluent (of an aqueous solution having 300-8000 ppm NH3-N) produced by the systems and methods disclosed herein may have 0.1-1% ammonia, for example, 0. 1-0.3% ammonia, 0.3-0.5% ammonia, 0.5-0.8% ammonia, or 0.8-1.0% ammonia, or 1% or less ammonia, for example, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less ammonia.

[0092] In certain embodiments, at least 80-99% ammonia may be recovered from the aqueous solution, for example, at least 80-85%, at least 85-90%, at least 90-95%, at least 95- 97%, or at least 97-99% ammonia may be recovered from the aqueous solution. In some embodiments, the efficiency of ammonia recovery7may be at least 50%, for example, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0093] Thus, in certain exemplary embodiments, the effluent may comprise a target ammonia concentration of 1-200 ppm NFL-N. for example, 1-15 ppm, 15-25 ppm, 25-40 ppm, 40-70 ppm, 70-100 ppm, 100-125 ppm, 125-145 ppm, 145-155 ppm, 155-165 ppm, 165-175 ppm, 175-185 ppm, or 185-200 ppm NH3-N, but the target ammonia concentration may be selected based on the particular application. In accordance with certain embodiments, the method may be performed to produce an effluent having less than a threshold concentration of ammonia. The threshold concentration may be between 1-200 ppm NH3-N, for example 1 ppm, 15 ppm, 25 ppm, 40 ppm. 50 ppm, 60 ppm. 70 ppm, 100 ppm, 125 ppm. 135 ppm, 145 ppm, 155 ppm, Docket No. 202488138PPCT01

[0094] 165 ppm, 175 ppm, 185 ppm, or 200 ppm NHs-N, but the effluent threshold concentration of ammonia may be selected based on the particular application.

[0095] In some embodiments, the wastewater to be treated, for example, the raw wastewater, may be directed to a reservoir. Within the reservoir, the wastewater may reach equilibrium, for example, producing an aqueous solution which is substantially homogeneous. The reservoir may allow the aqueous solution to be circulated through the module(s) at a constant flow rate and with a substantially consistent composition. The raw wastewater may be associated with an industrial, manufacturing, agricultural, laboratory, or wastewater processing facility. In certain exemplary embodiments, the raw wastewater may be associated with a biological treatment process, for example, a methanogenesis treatment process. In certain exemplary embodiments, the raw wastewater may be associated with a clean process microelectronics manufacturing facility. Thus, in some embodiments, the aqueous solution may be substantially homogeneous.

[0096] The methods may comprise measuring one or more property, for example, of the aqueous solution, acidic solution (e.g.. first acidic solution and / or second acidic solution), acid, product, effluent, intermediate product, or within the system. The property may be measured within a reservoir or in-line. The methods may comprise measuring one or more of temperature, pH, pressure, density, specific gravity, conductivity, turbidity, total suspended solids (TSS), total organic carbon (TOC), ammonia concentration (e.g., nitrogen concentration), concentration of a contaminant, such as an inorganic constituent, or others. Other parameters that may be measured include, but are not limited to, H2O2 concentration, O2 concentration, or CO2 concentration. In certain exemplary embodiments, inorganic constituents may be measured, for example, to determine whether the concentration may be present at or near solubility limit may be measured. Exemplary inorganic constituents include calcium, magnesium, aluminum, iron, silicon dioxide, or others.

[0097] In certain exemplary embodiments, the methods may comprise measuring one or more property of the aqueous solution or effluent selected from pH, temperature, and level of saturation of certain contaminants, such as inorganic contaminants. If the level of contaminants is too high, the methods may include removing or reducing a concentration of one or more contaminants prior to introducing the aqueous solution into the module, to avoid or reduce scaling of the membrane and allow for efficient pH control.

[0098] In certain exemplary embodiments, the methods may comprise measuring one or more property of the acidic solution (e.g., first acidic solution and / or second acidic solution), product, or intermediate product selected from pH, temperature, density, specific gravity, Docket No. 202488138PPCT01 conductivity, concentration of the acid, ammonia concentration (e.g., nitrogen concentration), or ionic concentration, for example, sulfate or phosphate concentration. The methods may comprise adjusting the pH and / or concentration of acid in the acidic solution (e.g., first acidic solution and / or second acidic solution) responsive to the measured property.

[0099] In accordance with certain exemplary embodiments, the methods may comprise measuring or determining ammonia concentration of the raw wastewater or aqueous solution. In some embodiments, the methods may comprise measuring or determining ammonia concentration of an effluent. Ammonia concentration of a fluid may be measured with an ammonia nitrogen sensor. One or more parameter of the system or method may be adjusted responsive to ammonia concentration. The parameter may include, for example, flow' rate, temperature, pH. or any other parameter described herein.

[0100] In some embodiments, the methods may comprise measuring or determining ammonium concentration of an intermediate product or product. Ammonium concentration of the intermediate product or product may be measured or determined by measuring one or more of pH, density, and conductivity of the intermediate product. A correlation may be drawn between an increasing ammonium concentration in the intermediate product and a decreasing concentration of ammonia in the aqueous solution or effluent. Thus, the methods may comprise determining a rate of ammonia recovery from the aqueous solution.

[0101] One or more parameter of the system may be adjusted responsive to rate of ammonia recovery. In some embodiments, flow rate, pH or temperature may be adjusted to increase or decrease a rate of ammonia recovery. For instance, flow' rate of one or more of the aqueous solution and effluent or the acidic solution (e.g., first acidic solution and / or second acidic solution) and intermediate product may be independently adjusted to increase or decrease a rate of ammonia recovery.

[0102] Temperature is believed to have a relationship w ith rate of ammonia recover . Henry’s Law' Solubility Constant for ammonia generally increases with temperature as an exponential function. Therefore, at higher temperatures, ammonia gas is more volatile and more ammonia may be stripped per unit surface area of the membrane. Thus, in some embodiments, temperature of the acidic and aqueous solution may be controlled to increase or decrease a rate of ammonia recovery, but maintained within a temperature limit of the membrane material. Additionally, in some embodiments, pH of the acidic solution (e.g., first acidic solution and / or second acidic solution) may be adjusted to increase or decrease a rate of ammonia recovery’. For instance, pH of the acidic solution or aqueous solution may be adjusted to be within a target range to increase the rate of ammonia recovery. Docket No. 202488138PPCT01

[0103] The methods may comprise controlling a concentration of ammonium in the acidic solution (e.g., first acidic solution and / or second acidic solution). The concentration of ammonium may be in the form of ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium citrate, or other ammonium compound. The concentration of ammonium in the acidic solution may be controlled to be between 10% w / w and 50% w / w, for example, between 10% w / w and 20% w / w, between 20% w / w and 30% w / w. between 30% w / w and 40% w / w, between 20% w / w and 40% w / w. or between 40% w / w and 50% w / w.

[0104] The ammonium, for example, generated from the reaction within the module, may be used in the manufacture of an ammonium product, such as a fertilizer product. For instance, ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium citrate, or other ammonium compounds, may be useful as a fertilizer composition containing both nitrogen and other compounds, such as sulfur. In some embodiments, the ammonium product may be in a liquid fertilizer form. In other embodiments, the ammonium product may be crystalized into a dried fertilizer form. For example, in some embodiments, the method may comprise drying the ammonium product to produce a dried fertilizer.

[0105] In some embodiments, the generated ammonium, such as ammonium sulfate, may be used in water treatment for chloramination in distribution systems.

[0106] Thus, in some embodiments, the product and / or at least a fraction of the intermediate product comprising ammonium may be collected and used to manufacture an ammonium product, such as a fertilizer product or a chloramination product. The product and / or intermediate product may be collected from the lead module, end module, or an intermediate module, for example, from a lumen outlet. In some embodiments, the methods may comprise withdrawing a product comprising ammonium from a product reservoir.

[0107] In some embodiments, at least a fraction of the product or intermediate product may be recirculated to generate the acidic solution. For instance, the product or intermediate product may be directed back to a reservoir utilized as the source of the acidic solution, for example, as a source of the first acidic solution or the second acidic solution. An acid may be combined with the product or intermediate product to produce the acidic solution. The acid may be combined with the product or intermediate product in an amount effective to maintain a target pH or pH range of the acidic solution.

[0108] In general, any amount of free acid available will protonate ammonia and contribute to ammonia absorption. How ever, in some embodiments, additional acid may be introduced into the reservoir in an effective amount to maintain the target pH or pH range of the acidic solution. For instance, acid (e.g., sulfuric acid, phosphoric acid, nitric acid, citric acid, or Docket No. 202488138PPCT01 other) may be added to the reservoir, while an equivalent amount of acidic solution is purged from the reservoir. The exemplary acidic solution may, in certain embodiments, be maintained with less than 35% ammonium, for example, within 20-35% ammonium, for example, 20-25%, 25-30%, 30-35%, 35-40%, 40-45%, or 45-50% ammonium. The acidic solution may be maintained with at least 10% acid, for example, within 10%-14% acid. In other embodiments, the acidic solution may be maintained with less than 10% acid. Each of the first acidic solution and second acidic solution may be independently controlled.

[0109] In some embodiments, a product comprising ammonium, for example, ammonium sulfate, may be withdrawn from the reservoir. The product withdrawn from the reservoir may be used to generate an ammonium product, such as a fertilizer product, as previously described. In other embodiments, the product withdrawn from the reservoir may be purged. In some embodiments, the acid and product are introduced and withdrawn from the reservoir in a continuous mode. In other embodiments, the acid and product are introduced and withdrawn from the reser oir in a batch mode. By producing the acidic solution in the reservoir for recirculation, the solution may reach equilibrium, for example, the acidic solution may be substantially homogeneous, allowing the acidic solution to be circulated through the module(s) at a constant flow rate and with a substantially consistent composition.

[0110] Thus, the systems and methods disclosed herein may be used to efficiently produce an ammonium product and an effluent having a low concentration of ammonia.

[0111] In some embodiments, flow rate of the aqueous solution and / or acidic solution may be controlled. The methods may comprise directing the aqueous solution to the module at an exemplary flow rate of between about 150-250 mL / min, for example, 150-175 mL / min, 175- 185 mL / min, 185-200 mL / min, 200-225 mL / min, or 225-250 mL / min. In other embodiments, the methods may comprise directing the aqueous solution to the module at a flow rate of between 200-250 L / min, 250-300 L / min, 300-350 L / min, 350-400 L / min, 400-450 L / min, 450 -500 L / min.

[0112] The methods may comprise directing the acidic solution, e.g., the first acidic solution and / or the second acidic solution, to the module at a flow rate at least 2-10 times faster than the flow rate of the aqueous solution, for example, 2-4 times faster. 4-6 times faster, 6-8 times faster, or 8-10 times faster than the flow rate of the aqueous solution. In some embodiments, the ratio of the flow rate of the acidic solution to the flow rate of the aqueous solution is between 2-4: 1, for example, 2-2.5: 1, 2.5-3: 1, 3-3.5: 1, or 3.5-4: 1. In some embodiments, the ratio of the flow rate of the acidic solution to the flow rate of the aqueous solution is between Docket No. 202488138PPCT01

[0113] 4-6:1, 6-8: 1, or 8-10:1. The ratio of flow rate of the acidic solution to the aqueous solution may be selected to maintain a constant Reynold's Number as viscosity increases.

[0114] In some embodiments, the acidic solution may be directed to the module at an exemplary flow rate of between about 200-250 L / min, 250-300 L / min, 300-350 L / min, 350- 400 L / min, 400-450 L / min, 450 -500 L / min, 500-550 L / min, 550-600 L / min, 600-650 L / min, 650-700 L / min, or 700-750 L / min. In other embodiments, the acidic solution may be directed to the module at an exemplary flow rate of between about 1,000-1,500 mL / min, for example, 1,000-1,100 mL / min, 1,100-1,200 mL / min, 1,200-1,300 mL / min, 1,300-1,400 mL / min, or 1,400-1,500 mL / min. In general, the flow rate of the acidic solution may be selected responsive to the module size and flow rate of the aqueous solution.

[0115] It should be understood that flow rate may generally be scaled with module size. Thus, higher flow rates (for example, greater than the exemplary flow rates of 250 mL / min or 1,500 mL / min) may be utilized with larger modules. Furthermore, flow rate of the aqueous solution and acidic solution, e.g., first acidic solution and / or second acidic solution, may be selected to control turbulence within the module. In some embodiments, flow rate may be selected to create turbulent flow, e.g., having a Reynolds number greater than 2,000.

[0116] FIG. 1 is a box diagram of a system 1000 for recovering ammonia from an aqueous solution. The system 1000 may comprise a plurality of modules, including a lead module 110 and an end module 130 positioned in series. In certain embodiments, the system may have 2- 5 modules arranged in series or more, for example, 2 modules, 3 modules, 4 modules, or 5 modules or more. The exemplary system 1000 of FIG. 1 includes one intermediate module 120 positioned between the lead module 110 and the end module 130, however the system may be free of intermediate modules 120 or may comprise more than one intermediate module 120.

[0117] The system 1000 may include a source of an aqueous solution 210 fluidly connected to the modules 110, 120, 130 in series. In particular, the source of the aqueous solution 210 may be directly fluidly connected to the lead module 110. The system 1000 may include a source of an acidic solution 310 fluidly connected to the modules 110, 120, 130 in series. In particular, the source of the acidic solution 310 may be directly fluidly connected to the end module 130. In certain embodiments, the source of the acidic solution 310 may be fluidly connected to additional modules, for example, to the lead module 110 or an intermediate module 120 (shown in dashed lines in FIG. 1). The acidic solution may optionally be directed to the additional module as required to control pH of the acidic solution at the module. Each module 1 10, 120, 130 may produce an effluent by removing ammonia from the aqueous Docket No. 202488138PPCT01 solution. Each module 110, 120, 130 may produce an intermediate product comprising ammonium.

[0118] The source of the aqueous solution 210 and / or the source of the acidic solution 310 may comprise reservoirs. The system 1000 may produce an effluent, which is optionally directed to an effluent reservoir 220. The system 1000 may include a return conduit fluidly connecting the modules 110. 120, 130 back to the source of the acidic solution 310. In certain embodiments, the system 1000 may include one or more draw lines to collect a portion of the intermediate product downstream from a module 110, 120, 130, and upstream from the source of the acidic solution 310. The system 1000 may produce a product, either from the one or more draw lines or from the acidic solution reservoir 310, which is optionally directed to a product reservoir 320. The system 1000 may include a source of an acid 330 fluidly connected to the source of the acidic solution 310. The source of the acidic solution 310 may include a discharge outlet. In the exemplary embodiment of FIG. 1, the discharge outlet is fluidly connected to optional product reservoir 320. In some embodiments, a source of raw wastewater (not shown) may be fluidly connected to the source of the aqueous solution 210.

[0119] The source of the aqueous solution 210 may be fluidly connected to a shell inlet of the lead module 110. The lead module 110 may produce a first effluent from the aqueous solution through the shell side. The shell outlet of the lead module 110 may be fluidly connected to the shell inlet of the intermediate module 120 and end module 130. In exemplary system 1000, the shell outlet of the lead module 110 is fluidly connected to the shell inlet of the end module 130 via the intermediate module 120. Thus, the shell outlet of the lead module 110 may be fluidly connected to direct the first effluent to the shell inlet of the intermediate module 120, while the shell outlet of the intermediate module 120 may be fluidly connected to direct a second effluent to the shell inlet of the end module 130. The shell outlet of the end module 130, from which a final effluent may be produced, may be fluidly connected to the effluent reservoir 220.

[0120] The source of the acidic solution 310 may be fluidly connected to a lumen inlet of the end module 130. The end module 130 may produce a first intermediate product through the lumen side. In general, the acidic solution and intermediate product may be directed through each module 110, 120, 130 in a countercurrent direction opposite the aqueous solution and effluent. The lumen outlet of the end module 130 may be fluidly connected to the lumen inlet of the intermediate module 120 and the lead module 110.

[0121] In exemplary system 1000. the lumen outlet of the end module 130 is fluidly connected to the lumen inlet of the lead module 110 via the intermediate module 120. Thus, Docket No. 202488138PPCT01 the lumen outlet of the end module 130 may be fluidly connected to direct the first intermediate product to the lumen inlet of the intermediate module 120. while the lumen outlet of the intermediate module 120 may be fluidly connected to direct a second intermediate product to the lumen inlet of the lead module 110.

[0122] The lumen outlet of the first module 110, from which the third intermediate product may be produced, may be fluidly connected to the product reservoir or to the source of the aqueous solution 310 via a return conduit. In some embodiments, as previously described, the intermediate product may be dosed with acidic solution to control pH. Furthermore, in some embodiments, at least some of the intermediate product may be draw n between modules for collection as an ammonia product, such as a fertilizer product.

[0123] In certain embodiments, the system may comprise a plurality of rows, each row including a plurality of modules. The pl ural i ty of modules in each row may be arranged in series. The plurality of rows may be arranged in parallel. In certain embodiments, the system may comprise 2-10 rows, for example, 2 rows, 3 rows, 4 rows, 5 rows, 6 rows, 7 rows, 8 rows. 9 rows, or 10 rows. The number of rows may be scaled, for example, to include more than 10 rows. Each row may include 2-5 modules in series or more, as previously described with respect to exemplary system 1000.

[0124] FIG. 2 is a box diagram showing an exemplary system 2000 including a plurality of row s. A first row of system 2000 includes lead module 110A and end module 130A. The first row of system 2000 includes intermediate module 120A. Each row may be free of an intermediate module 120 A or include more than one intermediate module 120A. A second row of system 2000 includes lead module HOB and end module 130B. The second row of system 2000 includes intermediate module 120B. The number of modules in each row may be the same, as shown in system 2000, or different. Thus, in certain embodiments, the number of modules in each row may be independently selected.

[0125] The plurality of modules 1 10A, 120 A, 130A are arranged in series, as previously described with respect to system 1000. Furthermore, the plurality7of modules HOB, 120B, BOB are arranged in series, as previously described with respect to system 1000. In exemplary system 2000, each lead module 110A, 110B is independently fluidly connected to the source of the aqueous solution 210 through a respective shell inlet. Similarly, in exemplary system 2000, each end module BOA, BOB is independently fluidly connected to the source of the acidic solution 310 through a respective lumen inlet. In exemplary system 2000, each end module BOA, BOB is fluidly connected to an effluent reservoir 220 through a respective shell outlet. Finally, in exemplary system 2000, each lead module 110A, 110B is Docket No. 202488138PPCT01 fluidly connected to the source of the acidic solution 310 by a return conduit fluidly connected to each respective lumen outlet.

[0126] While exemplary system 2000 includes a common source of the aqueous solution 210, source of the acidic solution 310, and effluent reservoir 220 for all rows, it should be noted that, in other embodiments, each row may include independent reserv oirs for one or more of the source of the aqueous solution 210, the source of the acidic solution 310. and the optional effluent reservoir 220. In other embodiments, a fraction of the rows may be fluidly connected to common reservoirs. For example, 2-10 rows or more may be connected to a common source of the aqueous solution 210, source of the acidic solution 310, and / or effluent reservoir 220. In such embodiments, the system may further be scaled up by including a plurality of each reservoir of the source of the aqueous solution 210, the source of the acidic solution 310, and / or the effluent reservoir 220. The number of rows fluidly connected to each reservoir may be independently selected.

[0127] In some embodiments, the system may include one or more flow control subsystems configured to control flow rate of the aqueous solution and / or the acidic solution. For instance, the system may include a flow control subsystem configured and arranged to control flow rate of the aqueous solution and effluent through the modules. The system may include a flow control subsystem configured and arranged to control flow rate of the acidic solution and intermediate product through the modules. In general, flow rates of the aqueous solution and effluent may be jointly controlled. Separately and independently, flow rates of the acidic solution and intermediate product may be jointly controlled. The flow control subsystems may be programmed to control flow rate to be within a target flow rate range as previously described.

[0128] FIG. 3 is a box diagram of an exemplary system 3000 including flow control subsystems. The flow control subsystems include pump 211 and pump 313. Pump 211 is positioned to control flow rate of the aqueous solution and effluent through the shell side of modules 110, 120, 130. Pump 313 is positioned to control flow7rate of the acidic solution and intermediate product through the lumen side of modules 110, 120, 130 in a countercurrent direction as the aqueous solution and effluent. In some embodiments, pumps 211 and 313 may be operably connected to controller 400. The controller 400 may be programmed to direct pumps 211 and / or 313 to control flow7rate of the aqueous solution, effluent, acidic solution, and intermediate product through modules 110, 120, 130.

[0129] In certain embodiments, the flow control subsystem may comprise one or more sensors, such as a flow meter. The flow meter may be positioned to measure flow rate of one Docket No. 202488138PPCT01 or more of the aqueous solution, effluent, acidic solution, and intermediate product through the modules. The flow meter may be operably connected to one or both of pump 211 and pump 313. The pump 21 1 or pump 313 may be programmed to control flow rate responsive to a measurement received from the flow meter. In some embodiments, the flow meter and / or pump may be operably connected to controller 400. The controller 400 may be programmed to direct one or both of pump 211 and pump 313 to operate responsive to the measurement received from the flow meter.

[0130] In some embodiments, the system may include one or more temperature control subsystems. The temperature control subsystems may be programmed to control temperature of the aqueous solution and / or the acidic solution. In some embodiments, the temperature control subsystems may be programmed to control temperature to be within a target temperature range as previously described. The temperature control subsystem may additionally or alternatively be programmed to measure temperature of one or more of the aqueous solution, an effluent, the acidic solution, an intermediate product, or the product. In some embodiments, the temperature control subsystem may be programmed to control temperature responsive to a temperature measurement.

[0131] Exemplary system 3000 includes a temperature control subsystem configured to control temperature of the aqueous solution. In particular, system 3000 includes heat exchanger 260 positioned to heat or cool the aqueous solution within reservoir 210. The system may include a sensor, such as a temperature sensor. Sensor 240 may be configured to measure temperature of the aqueous solution within reservoir 210. In some embodiments, heat exchanger 260 is operably connected to sensor 240. Heat exchanger 260 may be programmed to control temperature of the aqueous solution responsive to a measurement of temperature received from sensor 240. In some embodiments, one or both of heat exchanger 260 and sensor 240 may be operably connected to controller 400. Controller 400 may be programmed to direct the heat exchanger 260 to control temperature of the aqueous solution, optionally responsive to a measurement of temperature received from sensor 240.

[0132] While exemplary system 3000 includes a temperature control subsystem configured to control temperature of the aqueous solution, it should be understood that the system may include an alternative or additional temperature control subsystem (including a heat exchanger and or temperature sensor) programmed to control temperature of the acidic solution.

[0133] In some embodiments, the system may include one or more pH control subsystems.

[0134] The pH control subsystems may include a source of an acid and / or a source of a base fluidly Docket No. 202488138PPCT01 connected to the aqueous solution and / or the acidic solution. The pH control subsystems may be programmed to control pH of the aqueous solution and / or the acidic solution. In some embodiments, the pH control subsystems may be programmed to control pH to be within a target pH range as previously described. The pH control subsystem may additionally or alternatively be programmed to measure pH of one or more of the aqueous solution, an effluent, the acidic solution, an intermediate product, or the product. In some embodiments, the pH control subsystem may be programmed to control pH responsive to a pH measurement.

[0135] Exemplary system 3000 includes a pH control subsystem configured to control pH of the acidic solution. The pH control subsystem includes source of an acid 330 and valves 331, 312. Valve 331 is positioned to control flow of the acid from reservoir 330 into the acidic solution reservoir 310. Valve 312 is positioned to control flow of the acidic solution from reservoir 310 through a discharge outlet to optional product reservoir 320. Valves 331, 312 may be programmed to introduce acid and remove acidic solution to maintain a target pH range within the reservoir 310. The pH control subsystem may include a sensor, such as a pH sensor. Sensor 340 may be configured to measure pH of the acidic solution within reservoir 310. In some embodiments, valves 331, 312 may be operably connected to sensor 340. The valves 331, 312 may be programmed to be actuated responsive to a measurement of pH received from the sensor 340. In some embodiments, one or more of valve 331, valve 312, and sensor 340 may be operably connected to controller 400. Controller 400 may be programmed to direct the valves 331, 312 to control pH of the acidic solution, optionally responsive to a measurement of pH received from sensor 340.

[0136] While exemplary system 3000 includes a pH control subsystem configured to control pH of the acidic solution, it should be understood that the system may include an alternative or additional pH control subsystem (including a source of an acid or a base, one or more valve, and / or a pH sensor) programmed to control pH of the aqueous solution. For example, the system may comprise a source of a base fluidly connected to the aqueous solution. In certain exemplary embodiments, the base may comprise sodium hydroxide (NaOH) (as shown in FIG. 5), potassium hydroxide (KOH), or another hydroxide base. The base may be added to the aqueous solution in an amount effective to maintain a target pH range, for example, to maintain a pH above 7, for example, betw een 7-12. In other embodiments, the base may be added in an amount effective to maintain a pH above 10, for example, between 10-12, for example, 10-10.5. 10.5-11, 11-11.5, or 11.5-12. The target pH may be selected to maintain ammonia in the aqueous solution at the working temperature. Docket No. 202488138PPCT01

[0137] The system may include one or more of sensors 240, 340, 250, 350. As shown in exemplary system 3000, sensor 240 is positioned to measure a parameter of the aqueous solution, sensor 340 is positioned to measure a parameter of the acidic solution, sensor 250 is positioned to measure a parameter of the effluent, and sensor 350 is positioned to measure a parameter of the product. The sensors 240, 340, 250, 350 may be configured to measure one or more of temperature, pH, density, conductivity, turbidity, specific gravity, total suspended solids (TSS). total organic carbon (TOC), H2O2 concentration, ammonia concentration, O2 concentration, CO2 concentration, or composition, for example, concentration of one or more compound. It should be understood that sensors 240, 340, 250, 350 may be formed of a single sensor or multiple sensors, optionally each sensor configured to measure a different parameter.

[0138] While exemplary sensors 240, 340, 250, 350 of system 3000 are shown in communication with reservoirs 210, 310, 220, 320, respectively, it should be understood that one or more of sensors 240, 340, 250, 350 may be positioned in-line in communication with a relevant conduit. Furthermore, the system may include a sensor positioned to measure a parameter of the intermediate product. The sensor configured to measure a parameter of the intermediate product may be in communication w ith a reservoir holding the intermediate product or in-line in communication with the intermediate product return conduit.

[0139] Thus, in some embodiments, the system may include a controller 400. The controller may be operably connected to one or more flow control subsystem, for example, one or both of pump 211 and pump 313. The controller 400 may be operably connected to the temperature control subsystem, for example, heat exchanger 260. The controller 400 may be operably connected to the pH control subsystem, for example, one or both of valve 331 and valve 312. Thus, the controller 400 may be programmed to control one or more of flow rate, temperature, and pH within the system. In some embodiments, the controller 400 may be operably connected to one or more of sensor 240, sensor 340, sensor 250, and sensor 350. The controller 400 may be programmed to control one or more of flow rate, temperature, and pH responsive to a measurement received from one or more of sensor 240, sensor 340, sensor 250, and sensor 350. The controller 400 may be connected to the one or more components through a wireless connection. For example, the controller may be connected through wireless local area networking (WLAN) or short-wavelength ultra-high frequency (UHF) radio waves.

[0140] The controller 400 may be associated with one or more processors typically connected to one or more memory devices. The memory device may be used for storing programs and Docket No. 202488138PPCT01 data during operation of the system. For example, the memory device may be used for storing historical data relating to the parameters over a period of time, as well as operating data. In some embodiments, the controller 400 disclosed herein may be operably connected to an external data storage. For instance, the controller 400 may be operable connected to an external server and / or a cloud data storage. Thus, the controller 400 may be configured to transmit data to a memory storing device or a cloud-based memory storage. Such data may include, for example, operating parameters, measurements, and / or status indicators of the system components.

[0141] The stored data may be accessed through a computer or mobile device. In some embodiments, the controller 400 or a processor associated with the memory storage may be configured to notify a user of an operating parameter, measurement, and / or status of the system components. For instance, a notification may be pushed to a computer or mobile device notify ing the user. Operating parameters and measurements include, for example, properties of the aqueous solution, acidic solution, effluent, intermediate product, or product. Status of the system components may include, for example, status of one or more sensor, pump, or valve, such as whether the system component is offline (disconnected from the controller 400), has lost power, requires adjustment, requires maintenance (planned or unplanned maintenance), and / or fill level of a reservoir. However, the notification may relate to any operating parameter, measurement, or status of a system component disclosed herein. In certain embodiments, information, such as system updates, may be transmitted to the controller 400 from an external source.

[0142] The controller 400 may further be configured to access data from the memory storing device or cloud-based memory storage. The controller 400 may be programmed to predict operation of the system based on historical data stored in the memory storage. For instance, the controller 400 may be programmed to predict future adjustments required to the flow control, temperature control, or pH control based on current measured parameters and historical data. The controller 400 may additionally be programmed to predict whether a system component will require adjustment or maintenance based on current measured parameters and historical data. In some embodiments, one or more of the processes disclosed herein may be manually or semi-automatically executed.

[0143] In some embodiments, the system may comprise one or more manifold configured to distribute fluid streams. FIG. 4 is a box diagram showing an exemplary system 4000 including a first row of modules 110A, 120A, 130A and second row of modules HOB, 120B, 130B. The exemplary system 4000 includes manifolds 115, 215, 315 positioned to distribute Docket No. 202488138PPCT01 fluid streams. In particular, manifold 115 is positioned to integrate a first intermediate product from module 110A and a second intermediate product from module HOB into a return conduit directed to the acidic solution reservoir 310. Manifold 215 is positioned to distribute aqueous solution from the source of the aqueous solution 210 to module 110A and module HOB. Manifold 315 is positioned to distribute acidic solution from the source of the acidic solution 310 to module 130A and module 130B. Manifolds 115, 215, 315 may be operably connected to controller 400. Thus, in some embodiments, controller 400 may be programmed to control distribution of one or more flow streams within the system by actuating one or more of manifold 115, manifold 215, and manifold 315.

[0144] In some embodiments, one or more separation device or filter, for example, cartridge filter (FIG. 5), may be used to collect unwanted contaminants, such as scale-forming agents, debris, or other contaminants, from the aqueous solution, effluent, acidic solution, intermediate product, or product. For instance, a separation device or filter may be positioned to separate contaminants that may otherwise collect or form scale on the membrane. In certain exemplary embodiments, the filter may be a 5 micron cartridge filter. The separation device or filter may be positioned downstream from the source of the aqueous solution or downstream from the source of the acidic solution. In some embodiments, the separation device or filter may be positioned downstream from the shell outlet of the end module. In some embodiments, the separation device or filter may be positioned downstream from the lumen outlet of the lead module. In some embodiments, the separation device or filter may be positioned downstream from the discharge outlet of the source of the acidic solution.

[0145] In some embodiments, the system may include a source of a catalyst, such as a hydrogen peroxide (H2O2) destroying catalyst, fluidly connected to the source of the aqueous solution or an effluent. One exemplary catalyst is a catalytic carbon or other catalytic media. The catalyst may be selected to be compatible w ith the working pH. In other embodiments, the catalyst may comprise OPTIMASE™ catalase enzyme (FIG. 5). For semiconductor manufacturing systems, an H2O2 destroying catalyst may be beneficial to degrade H2O2 in the aqueous solution or effluent.

[0146] FIG. 5 is a schematic diagram of a benchtop system for recovering ammonia from an aqueous solution, as used in the tests of the examples below-. The system of FIG. 5 includes a feed source of an aqueous solution comprising ammonia. For the purposes of the benchtop experiments, the aqueous solution was optionally spiked ammonium sulfate ((NH4)2SO4) and hydrogen peroxide (H2O2). OPTIM ASE™ catalase enzyme and sodium hydroxide (NaOH) are fluidly connected to the raw wastewater in a feed tank maintained at 95°F (35°C). A first Docket No. 202488138PPCT01 pump directs the aqueous solution to a cartridge filter positioned upstream from the lead module, module A. Three modules, module A, module B, and module C are positioned in series with respect to the aqueous solution. Each module contains a respective sampling valve. An effluent tank is positioned downstream from module C. A recycle conduit connects module B and module C to a tank storing the acidic solution. Sulfuric acid (H2SO4) is directed to the acidic solution tank, which is maintained at 100°F (38°C), at a target temperature of 3 °F to 9 °F greater than the raw wastewater feed tank. A second pump directs the acidic solution to a cartridge filter positioned upstream from the modules, which are arranged in parallel with respect to the acidic solution.

[0147] FIG. 9 is a box diagram of an exemplary system 9000 including a lead module 110 constructed and arranged as a saturator. Exemplary system 9000 includes lead module 110 and end module 130. The system 9000 includes a source of an aqueous solution 210 fluidly connected to modules 110 and 130 in series. The source of the aqueous solution 210 is directly fluidly connected to the lead module 110. The system 9000 includes a source of a first acidic solution 360 fluidly connected to module 110 and a source of a second acidic solution 310 fluidly connected to module 130. In particular, the source of the first acidic solution 360 is directly fluidly connected to the lead module 110 and the source of the second acidic solution 310 is directly fluidly connected to the end module 130.

[0148] System 9000 also includes product reser oir 320 and effluent reservoir 220. The product reservoir 320 is positioned downstream from the lumen outlet of the lead module 110. In certain embodiments, the lumen outlet of the end module 130 may be fluidly connected to the product reservoir 320. The effluent reserv oir 220 is positioned downstream from the shell outlet of the end module 130.

[0149] As shown in FIG. 9, the lumen outlet of the lead module 110 is fluidly connected to the source of the first acidic solution 360 by a first return conduit. The lumen outlet of the end module 130 is fluidly connected to the source of the second acidic solution 310 by a return conduit. Additionally, the source of the second acidic solution 310 is fluidly connected to the source of the first acidic solution 360. A source of an acid 330 (FIG. 1) may be fluidly connected to the source of the second acidic solution 310 and / or to the source of the first acidic solution 360.

[0150] FIG. 10 is a box diagram of an alternate system 9500, which is similar to system 9000, except that it also includes an intermediate module 120. As previously described, the system may include one or more intermediate modules, for example, 2 to 5 or more intermediate modules. In exemplary system 9500, the source of the second acidic solution Docket No. 202488138PPCT01

[0151] 310 is fluidly connected to intermediate module 120 and end module 130 in series. The source of the second acidic solution 310 is directly fluidly connected to the intermediate module 120. However, in other embodiments, the source of the second acidic solution 310 may be directly fluidly connected to the end module 130. An intermediate product produced by the intermediate module 120 is directed to the end module 130. In some embodiments, at least a portion of the intermediate product may be fluidly connected to product reservoir 220.

[0152] Although not shown in FIGS. 9-10 for clarity, it should be noted that systems 9000 and 9500 may include any one or more of the sensors, valves, pumps, controller, or other features described herein.

[0153] In accordance with another aspect, there is provided a method of retrofitting a system having at least one module. The method may comprise providing a lead module and fluidly connecting the source of the aqueous solution to a shell inlet of the lead module. The method may comprise fluidly connecting the shell outlet of the lead module to the shell inlet of the existing module. The method may comprise fluidly connecting the lumen outlet of the existing module to the lumen inlet of the lead module. In certain embodiments, the methods may comprise providing one or more intermediate modules and connecting the intermediate module(s) in series as described herein.

[0154] In some embodiments, the methods may comprise fluidly connecting the lumen inlet of the lead module to a source of a first acidic solution, which has a higher pH than the source of the acidic solution which is fluidly connected to the lumen inlet of the existing module. The lumen outlet of the existing module may be fluidly connected to the source of the acidic solution. Thus, in some embodiments, the method of retrofitting may comprise fluidly connecting the lead module as a saturator.

[0155] In some embodiments, the methods may comprise fluidly connecting the source of the second acidic solution to the source of the first acidic solution. In some embodiments, the methods may comprise fluidly connecting the lumen outlet of the lead module to a product reservoir.

[0156] In accordance with another aspect, there is provided a method of facilitating recovery of ammonia from an aqueous solution. The method may include providing instructions to fluidly connect one or more membranes, as described herein. The methods may comprise providing instructions to fluidly connect a source of an aqueous solution to a lead module and a source of an acidic solution to an end module. In certain embodiments, the methods may comprise providing instructions to fluidly connect a source of a first acidic solution to the lead module and a source of a second acidic solution to the end module, as described herein. Docket No. 202488138PPCT01

[0157] Next, in accordance with another aspect of the present disclosure, the system may be configured to exploit the temperature dependence of ammonia volatility .

[0158] Henry’s Solubility Constant (Ku(soi)) describes the solubility of a gas in a liquid as a function of the partial pressure of the gas above the solution at equilibrium. On the other hand, Henry ’s Volatility7Constant (KH(V>) is the inverse of the solubility constant, representing the tendency of gas to escape from a liquid into the gas phase as a function of the gas’s solubility at equilibrium.

[0159] As shown in Table 1 below and FIGS. 11 and 12, it has been found that Henry’s Solubility' Constant (KH(SO1)) for ammonia decreases significantly with increasing temperature, resulting in greater ammonia volatility and greater rate of diffusion through gas-permeable membranes. For example, Henry's Volatility Constant (KH(V>) for ammonia increases by a factor of 5.56 between 20°C and 60°C, which correlates with a proportional increase in the diffusion rate. Table 1: Henry7’s Law Volatility Constant [atm L atm’1] for Ammonia 0-60° C in Water Docket No. 202488138PPCT01

[0160] Accordingly, in another aspect of the present disclosure, the system for treating an aqueous solution may include one or more heating subsystems configured to maintain the aqueous solution and acidic solution at elevated temperatures. In some embodiments, one or more of the aqueous solution and acidic solution may be heated to between, e.g., 35°C (95°F) and 65°C (150°F). In some embodiments, the acidic solution may be maintained at a temperature higher than the aqueous solution by, e.g.. 3°F to 9°F to prevent condensation and maintain optimal diffusion, as described above. These features may enable higher ammonia removal rates per module and, in some embodiments, may reduce the number of modules needed, thereby improving overall system footprint and economics.

[0161] In some embodiments, the one or more heating subsystems may include a pre-heat exchanger configured to pre-heat the aqueous solution comprising ammonia with an effluent solution.

[0162] Without wishing to be bound by theory, it is believed that the rate of ammonia diffusion across the membrane is positively correlated with ammonia volatility. Thus, operating the system at elevated temperatures can significantly increase ammonia removal efficiency per module. For instance, a system operated at 60°C may achieve similar ammonia removal performance in a single module as a system operated at 35°C with multiple modules. Accordingly, this improvement may reduce capital expenditure and / or operating expenditure while potentially enabling higher ammonium product concentrations.

[0163] In some embodiments, the one or more membrane modules utilized in the system for treating an aqueous solution may be constructed with one or more membranes capable of withstanding high temperatures. Additionally and / or alternatively, other components of the membrane module(s) comprise high-temperature-resistant materials such as, e.g., the epoxy and / or thermoplastic housing retaining the membrane(s) within the module(s).

[0164] Furthermore, it is to be understood that this inventive concept may be combined with other features disclosed herein such as, e.g., pH control and dual-loop acidic solution circulation in order to optimize ammonia recovery and product quality.

[0165] In addition, incorporating heat recovery or preheating the ammonia stream to at or near the operating temperature with one or more streams from one or more of the modules should at least partially reduce operating cost associated with the system at, for example, 60°C. Docket No. 202488138PPCT01

[0166] Examples

[0167] The function and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be limiting the scope of the invention.

[0168] Example 1: Benchtop Test using Aqueous Solution Spiked with Ammonium Sulfate ((NH4)2SO4)

[0169] Preparation of Aqueous Solution

[0170] A batch of aqueous solution (60L) was prepared by spiking the sample with ammonium sulfate (758 g, at 12.6 g / L) to more closely resemble a maximum ammonia concentration from NH4F of known historical samples. The solution was adjusted to a pH of 11.3 with sodium hydroxide. The ammonia concentration target was 4,600 mg / L N, equivalent to approximately 6,000 mg / L NH4+. However, the actual ammonia concentration in the aqueous feed solution was determined to be 4,181 mg / L N after analysis.

[0171] Preparation of Acidic Solution

[0172] A batch of acidic solution (19L) was prepared by combining a synthetic ammonium sulfate solution from a previous test (to resemble steady state operating conditions) with sulfuric acid (0.95 g / L) dosing to reach a pH of 1.65.

[0173] Operating Parameters

[0174] The exemplary system of FIG. 5 was operated according to the parameters shown in Table 1 below. The modules w ere Liqui-Cel™ Membrane contactors (distributed by 3M™, Maplewood, MN) having dimensions of 2.5 in diameter by 8 in length and a membrane contact area of 16 ft2. The cartridge filters were 5 micron cartridge filters.

[0175] Table 2: Operating Parameters Docket No. 202488138PPCT01

[0176] The pilot unit processed about 46 liters of aqueous solution over a period of 4 hours. Operating data was collected, and grab samples were taken from the reservoirs every 30 minutes.

[0177] Test Results

[0178] The results are presented in Table 3 below and in the graph of FIG. 6.

[0179] Table 3: Test Results for Benchtop Test with Ammonium Sulfate

[0180] * Percent by weight based on ammonia analysis

[0181] **Cumulative dose of supplemental H2SO4 to maintain pH 1.7 in the acidic solution

[0182] As shown in Table 3, the membrane contactor unit removed 97.6% of the ammonia nitrogen from the aqueous solution containing 4,181 mg / L NH3-N and produced an effluent containing 100 mg / L NH3-N (129 mg / L NH4). The membrane contactor pilot unit thus met an effluent quality target of 155mg / L NH3-N (200 mg / L NH4). Table 2 also shows that fluoride was retained in the aqueous solution (< 0.2 mg / L F in the final acidic solution) as ammonia concentration increased from 17,804 to 27,036 mg / L N in the acidic solution tank.

[0183] A 97.6% ammonia recovery efficiency from 46 liters of aqueous solution containing 4,181 g / L NH3-N would be expected to add 9.919 mg / L NH3-N to 18.9 liters of the acid scrubbing solution. Table 3 shows that the ammonia concentration increased by 9,232 mg / L NH3-N, which is 93% of the expected recovery.

[0184] The basicity of the effluent and acidity7of the acidic solution stream immediately downstream from the lead module were determined to be adequate for ammonia removal from the aqueous solution. As shown in the graph of FIG. 6, the percentages of ammonia Docket No. 202488138PPCT01 removal for the three membrane contactor modules were relatively stable over the time period of the test. The average ammonia removal rates were 83%, 67%, and 52% for the lead, intermediate (middle), and end (lag) modules, respectively.

[0185] Accordingly, under the tested parameters, the benchtop system was capable of meeting a target final ammonia concentration in the effluent tank of 200 mg / L NH4 or less (actual final ammonia concentration was 129 mg / L NH4). This test shows the ability of the system to remove ammonia from the aqueous solution while utilizing a countercurrent recirculated acidic solution at steady state with the addition of sulfuric acid as needed to maintain a desired pH range.

[0186] Example 2: Benchtop Test using Aqueous Solution without Ammonium Sulfate ((NH4)2SO4)

[0187] A second test was performed under identical conditions as example 1 and using the exemplary7system of FIG. 5, except that the aqueous solution was not spiked with ammonium sulfate. The aqueous solution had an actual ammonia concentration of 1,910 mg / L N. The acidic solution was prepared by dosing the remaining acidic solution from example 1 (to resemble steady state operating conditions) with an effective amount of sulfuric acid to reach a pH of 1.65.

[0188] Test Results

[0189] The results are presented in Table 4 below and in the graph of FIG. 7.

[0190] Table 4: Test Results for Benchtop Test without Ammonium Sulfate

[0191] * Percent by weight based on ammonia analysis

[0192] **Cumulative dose of supplemental H2SO4 to maintain pH 1.7 in the acidic solution Docket No. 202488138PPCT01

[0193] As shown in Table 4. the membrane contactor unit removed 97.8% of the ammonia nitrogen from the aqueous solution containing 1,910 mg / L NFh-N and produced an effluent containing 41 mg / L NHs-N (53 mg / L NH4). The membrane contactor pilot unit met an effluent quality target of 155 mg / L NH3-N (200 mg / L NFL). Table 4 also shows that all fluoride was rejected by the membrane (< 0.2 mg / L F in the final acidic solution) as ammonia concentration increased from 28,838 to 31,807 mg / L N in the acidic solution tank.

[0194] A 97.8% ammonia recovery efficiency from 46 liters of aqueous solution containing 1,910 g / L NH3-N would be expected to add 4,608 mg / L NH3-N to 18.9 liters of the acidic scrubbing solution. However, Table 4 shows that the ammonia concentration increased by 2,972 mg / L NH3-N in the acidic solution, which is only 64% of the expected recovery.

[0195] The basicity of the effluent and acidity of the acidic solution stream immediately downstream from the lead module were determined to be adequate for ammonia removal from the aqueous solution. As show n in the graph of FIG. 7, the percentages of ammonia removal for the three membrane contactor modules were relatively stable over the time period of the test. The average ammonia removal rates were 73%, 76%, and 64% for the lead, intermediate (middle), and end (lag) modules, respectively.

[0196] Accordingly, under the parameters of the second test, the benchtop system was capable of meeting a target final ammonia concentration in the effluent tank of 200 mg / L NH4 or less (actual final ammonia concentration was 53 mg / L NH4). This test shows the ability of the system to remove ammonia from the aqueous solution (having a lower ammonia nitrogen concentration) while utilizing a countercurrent recirculated acidic solution at steady state with the addition of sulfuric acid as needed to maintain a desired pH range.

[0197] Example 3: Benchtop Test using Aqueous Solution and Acidic Solution Spiked with Ammonium Sulfate ((NH4)ISO4)

[0198] A third test was performed under identical conditions as example 1 and using the exemplary system of FIG. 5, except that the acidic solution was also spiked with ammonium sulfate. The aqueous solution had an actual ammonia concentration of 4,653 mg / L N. The acidic solution w as prepared by adding ammonium sulfate to the remaining acidic solution from example 2 to reach 25% (2,328 g ( TLyhSCL (123 g / L)) and dosing the solution with an effective amount of sulfuric acid to reach a pH of 1.65. Ammonium sulfate in the acidic solution increased from 25.5% to 31.8% during the test. Docket No. 202488138PPCT01

[0199] Test Results

[0200] The results are presented in Table 5 below and in the graph of FIG. 8.

[0201] Table 5: Test Results for Benchtop Test with Ammonium Sulfate in Aqueous Solution and

[0202] Acidic Solution

[0203] * Percent by weight based on ammonia analysis

[0204] **Cumulative dose of supplemental H2SO4 to maintain pH 1.7 in the acidic solution

[0205] As shown in Table 5, the membrane contactor unit removed 96.9% of the ammonia nitrogen from the aqueous solution containing 4,653 mg / L NH3-N and produced an effluent containing 145 mg / L NH3-N (186 mg / L NH4). The membrane contactor pilot unit met an effluent quality target of 155 mg / L NH3-N (200 mg / L NH4). Table 5 also shows that all fluoride was rejected by the membrane (< 0.2 mg / L F in the final acidic solution) as ammonia concentration increased from 62,088 to 79,627 mg / L N in the acidic solution tank.

[0206] The data in Table 5 also shows that the ammonia concentration in the acidic solution tank increased by 17,539 mg / L NH3- N which represents a 158% recovery. This high recovery can result from an error as small as 4% in the initial and final ammonia readings in the acidic solution tank, which is an acceptable analytical error.

[0207] The basicity of the effluent and acidity of the acidic solution stream immediately downstream from the lead module w ere determined to be adequate for ammonia removal from the aqueous solution. As shown in the graph of FIG. 8, the percentages of ammonia removal for the three membrane contactor modules were relatively stable over the time period of the test. The average ammonia removal rates were 72%, 66%, and 68% for the lead, intermediate (middle), and end (lag) modules, respectively. Docket No. 202488138PPCT01

[0208] Accordingly, under the parameters of the third test, the benchtop system was capable of meeting a target final ammonia concentration in the effluent tank of 200 mg / L NH4 or less (actual final ammonia concentration was 186 mg / L NH4). This test shows the ability of the system to remove ammonia from the aqueous solution while utilizing a countercurrent recirculated acidic solution (having a greater ammonium concentration) at steady state with the addition of sulfuric acid as needed to maintain a desired pH range.

[0209] Example 4: Prophetic Example for Ammonia Recovery Using a Lead Module Configured as a Saturator

[0210] An ammoniated wastewater containing 3,000 mg / L of ammonia as nitrogen will treated for removal and recovery of ammonia with an exemplary system as shown in FIG. 10. The wastewater will be heated to 100°F and pumped into the lead module in series at a flow rate of 190 mL / min. The lead module will function as both an ammonia removal device and a scrubbing liquor saturating device (saturator). As such, it will be operated such that ammonia removal efficiency is compromised in the interest of neutralizing acidity and maximizing the ammonia concentration of the scrubbing liquor. Stated otherwise, the saturator will be operated to concentrate and saturate the scrubbing liquor (acidic solution) to achieve as close to a 2: 1 nitrogen-to-sulfate molar ratio and 40% w / w (NH4)2SO4 concentration as practical.

[0211] In this example, the lead module will be expected to reduce the concentration of ammonia in the wastewater by 75%. This level of performance can be facilitated by controlling the first acidic solution pH to a set-point of 3.5 s.u. at a temperature of 103°F. The acidic solution will be introduced at a flow rate of 684 mL / min (corresponding to 3.6x the wastewater flow rate).

[0212] The acidic solution will be continuously purged from the system at 5.5 mL / min at pH 3.78 s.u. with a concentration of 40% w / w (NH4)2SC>4 based on density (491 g / L). The acidic solution flow rate through the lead module will be maintained at a higher set-point than the other modules arranged in series to compensate for the increase in viscosity associated with the higher concentration of ammonium sulfate. The temperature of the acidic solution through the lead module will be maintained higher than the wastewater temperature by 3°F to prevent the acidic solution from being diluted by water vapor that would otherwise condense after diffusing through the membrane pores from the wastewater side of the membrane.

[0213] As concentrated acidic solution is purged from the system, the volume will be maintained by transferring 2.9 mL / min of dilute acidic solution from the circulating system of the down-stream modules (the intermediate and end module in FIG. 10) into the concentrated Docket No. 202488138PPCT01 acidic solution circulation loop. The mass balance will be maintained by also adding 1.4 ml / min of demineralized water and 0.8 mL / min of 93% (17.33 M) sulfuric acid to the concentrated acidic solution circulation loop. The amount of demineralized water required as make-up may be reduced by the incidental addition of water to the loop from water vapor condensation after being transported across the membrane due to localized or transient inversions of the thermal gradient across the membrane.

[0214] The effluent from the lead module in the series will flow to two additional modules, each of which will reduce the concentration of ammonia at the inlet of the module by 82% by utilizing counter-current acidic solution circulation. The acidic solution feeding the intermediate and end modules will be maintained at a temperature of 106°F to maintain a transmembrane temperature differential of 3°F over the effluent temperature existing the lead module in the series.

[0215] The dilute acidic solution will be maintained at pH of 2.0 s.u. The dilute acidic solution will be circulated at a flow rate of 448 m / L min (corresponding to 2.36x the effluent flow rate). The dilute acidic solution in this circulation loop will be transferred to the concentrated acidic solution circulation loop based on level control. In this example, the dilute acidic solution will be maintained at an equilibrium concentration of 25% w / w (NH4)2SO4 based on the relative removal efficiency of the contactors in the system. This concentration may vary with transients in the process or from one application to another.

[0216] The system volume and acidity’ in the dilute acidic solution circulation loop will be maintained by adding 2.5 mL / min of deionized water to the loop with 0.4 mL / min of 93% (17.33 M) H2SO4 to maintain a set-point pH of 2.0 s.u. In this example, the effluent discharged from each of the lead, intermediate, and end modules will have an ammonianitrogen concentration of 750, 135 and 24 mg / L NH3-N, respectively resulting in 99% overall ammonia removal.

[0217] Thus, the exemplary system having a lead module arranged as a saturator will have a very’ high rate of ammonia removal and recovery’. Furthermore, the use of acid in the exemplary system is optimized to reduce waste and produce a high quality product.

[0218] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as Docket No. 202488138PPCT01 additional items. Only the transitional phrases “consisting of and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0219] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0220] Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary’ and that actual parameters and / or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.

[0221] What is claimed is:

Claims

Docket No. 202488138PPCT01CLAIMS1. A system for treating an aqueous solution, comprising: a plurality of modules arranged in series, each module comprising a plurality of membranes, each membrane having a lumen side and a shell side, the plurality' of modules comprising a lead module having a shell inlet fluidly connected to a source of the aqueous solution comprising ammonia, a shell outlet, a lumen inlet fluidly connected to a source of a first acidic solution, and a lumen outlet. the plurality of modules comprising an end module having a lumen inlet fluidly connected to a source of a second acidic solution, a lumen outlet, a shell inlet, and a shell outlet, the shell outlet of the lead module being fluidly connected to the shell inlet of the end module, the first acidic solution having a higher pH than the second acidic solution.

2. The system of claim 1, wherein the lumen outlet of the lead module is fluidly connected to a first reservoir comprising the first acidic solution by a first return conduit.

3. The system of claim 2, wherein the lumen outlet of the end module is fluidly connected to a second reservoir comprising the second acidic solution by a second return conduit.

4. The system of claim 3, wherein the first acidic solution has a higher concentration of ammonium sulfate than the second acidic solution.

5. The system of claim 4, wherein the concentration of ammonium sulfate in the first acidic solution is between 20% w / w and 40% w / w.

6. The system of claim 3, wherein the source of the second acidic solution is fluidly connected to the source of the first acidic solution.

7. The system of claim 1, further comprising at least one intermediate module having a shell inlet, a shell outlet, a lumen inlet, and a lumen outlet, the shell inlet of the intermediate module being fluidly connected to the shell outlet of the lead module, the shell outlet of the intermediate module being fluidly connected to the shell inlet of the end module, the lumen inlet of the intermediate module being fluidly connected to the source of the second acidicDocket No. 202488138PPCT01 solution, and the lumen outlet of the intermediate module being fluidly connected to the lumen inlet of the end module.

8. The system of claim 1, wherein the first acidic solution has a pH between about 2.0 and 5.4 and the second acidic solution has a pH of 3.5 or less.

9. The system of claim 1, further comprising a flow control subsystem configured to control flow rate of the aqueous solution and the first acidic solution, wherein a ratio of the flow rate of the first acidic solution to the flow rate of the aqueous solution through the lead module is between about 3.5 and 4 to 1.

10. The system of claim 1, wherein a temperature of the first acidic solution is higher than a temperature of the aqueous solution.

11. The system of claim 10, wherein the temperature of the first acidic solution is between 3°F and 9°F higher than the temperature of the aqueous solution.

12. The system of claim 1, wherein the lumen outlet of the lead module is fluidly connected to a product reservoir.

13. The system of claim 1, wherein the system is configured to maintain the aqueous solution at a temperature between approximately 95°F and 150°F to enhance ammonia volatility.

14. The system of claim 13, wherein the system is configured to maintain the acidic solution at a temperature between approximately 3°F and 9°F higher than the aqueous solution.

15. The system of claim 14, further comprising a heating subsystem configured to heat the aqueous solution and the acidic solution to the respective temperatures.

16. The system of claim 15, further comprising a pre-heat exchanger configured to pre-heat the aqueous solution comprising ammonia.Docket No. 202488138PPCT0117. The system of claim 1, wherein at least one of the plurality of modules comprises one or more high-temperature resistant membranes capable of withstanding temperatures of at least 150°F.

18. The system of claim 17, wherein the at least one of the plurality of modules further comprises one or more membrane mounting materials capable of withstanding temperatures of at least 150°F.

19. A method of treating an aqueous solution comprising ammonia with a system comprising a plurality of modules, each module comprising a plurality of membranes, each membrane having a lumen side and a shell side, the method comprising: directing the aqueous solution comprising ammonia to a shell inlet of a lead module to produce a first effluent, the first effluent being fluidly connected to a shell inlet of an end module; directing a first acidic solution to a lumen inlet of the lead module, at least a portion of the ammonia in the aqueous solution being diffused through the plurality’ of membranes of the lead module to produce a product comprising ammonium; and directing a second acidic solution to a lumen inlet of the end module, at least a portion of the ammonia in the first effluent being diffused through the plurality’ of membranes of the end module to produce a first intermediate product comprising ammonium and a second effluent, the first acidic solution having a higher pH than the second acidic solution.

20. The method of claim 19, further comprising controlling pH of the first acidic solution to be between about 2.0 and 5.4 and controlling pH of the second acidic solution to be 3.5 or less.

21. The method of claim 19, further comprising controlling a temperature of the first acidic solution to be higher than a temperature of the aqueous solution.

22. The method of claim 21, comprising controlling the temperature of the first acidic solution to be between 3°F and 9°F higher than the temperature of the aqueous solution.

23. The method of claim 22, wherein the temperature of the aqueous solution is between 95°F and 150°F.Docket No. 202488138PPCT0124. The method of claim 18, further comprising controlling flow rate of the aqueous solution and the first acidic solution, wherein a ratio of the flow rate of the first acidic solution to the flow rate of the aqueous solution through the lead module is between about 3.5 and 4 to 1.

25. The method of claim 19, further comprising controlling a concentration of ammonium sulfate in the first acidic solution to be higher than a concentration of ammonium sulfate in the second acidic solution, the concentration of ammonium sulfate in the first acidic solution being controlled to be between 20% w / w and 40% w / w.

26. The method of claim 19, further comprising directing at least a portion of the product to a reservoir comprising the first acidic solution.

27. The method of claim 26, further comprising directing at least a portion of the first intermediate product to a reservoir comprising the second acidic solution.

28. The method of claim 27, further comprising directing at least a portion of the second acidic solution to the reservoir comprising the first acidic solution.

29. A method of facilitating recovers’ of ammonia from an aqueous solution, comprising: providing instructions to fluidly connect a shell inlet of a lead module having a plurality of membranes, each membrane having a lumen side and a shell side, to a source of an aqueous solution comprising ammonium; providing instructions to fluidly connect a lumen outlet of the lead module to a lumen inlet of an end module having a plurality of membranes, each membrane having a lumen side and a shell side; providing instructions to fluidly connect a lumen inlet of the lead module to a source of a first acidic solution and fluidly connect a lumen outlet of the lead module back to the source of the first acidic solution; and providing instructions to fluidly connect a lumen inlet of the end module to a source of a second acidic solution and fluidly connect a lumen outlet of the end module back to the source of the second acidic solution, the first acidic solution having a higher pH than the second acidic solution.Docket No. 202488138PPCT0130. The method of claim 29, further comprising providing instructions to fluidly connect the source of the second acidic solution to the source of the first acidic solution.

31. The method of claim 29, further comprising providing instructions to fluidly connect the lumen outlet of the lead module to a product reservoir.

32. A method of retrofitting a system for recovery of ammonia from an aqueous solution comprising an end module having a plurality of membranes, each membrane having a lumen side and a shell side, the method comprising: providing a lead module having a plurality of membranes, each membrane having a lumen side and a shell side; fluidly connecting a source of the aqueous solution to a shell inlet of the lead module; fluidly connecting a shell outlet of the lead module to a shell inlet of the end module; fluidly connecting a source of a first acidic solution to a lumen inlet of the lead module, and fluidly connecting a lumen outlet of the lead module back to the source of the first acidic solution, a source of a second acidic solution being fluidly connected to a lumen inlet of the end module, and a lumen outlet of the end module being fluidly connected back to the source of the second acidic solution, the first acidic solution having a higher pH than the second acidic solution.

33. The method of claim 32, further comprising fluidly connecting the source of the second acidic solution to the source of the first acidic solution.

34. The method of claim 32, further comprising fluidly connecting the lumen outlet of the lead module to a product reservoir.

35. A method of treating an aqueous solution comprising ammonia with a system comprising at least one module, the at least one module comprising at least one membrane, and the at least one membrane having a lumen side and a shell side, the method comprising: heating the aqueous solution comprising ammonia to a temperature between approximately 95°F and 150°F; directing the aqueous solution comprising ammonia to a shell inlet of the at least one module to produce an effluent;Docket No. 202488138PPCT01 heating an acidic solution to a temperature between approximately 3°F and 9°F higher than the aqueous solution; and directing the acidic solution to a lumen inlet of the at least one module, at least a portion of the ammonia in the aqueous solution being diffused through the at least one membrane of the at least one module to produce a product comprising ammonium.

36. The method of claim 35. wherein heating the aqueous solution and acidic solution increases ammonia volatility and improves diffusion efficiency across the at least one membrane.Docket No. 202488138PPCT01ABSTRACTA system for treating an aqueous solution is disclosed. The system includes a plurality of modules arranged in series, including a lead module having a shell inlet fluidly connected to a source of an aqueous solution having ammonia, a shell outlet, a lumen inlet fluidly connected to a source of a first acidic solution, and a lumen outlet, and an end module having a lumen inlet fluidly connected to a source of a second acidic solution, a lumen outlet, a shell inlet, and a shell outlet, the shell outlet of the lead module is fluidly connected to the shell inlet of the end module, the first acidic solution has a higher pH than the second acidic solution. Methods of treating an aqueous solution having ammonia with the system are also disclosed.

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