Systems and methods for recovering ammonia from aqueous solutions

Abstract

Systems and methods for recovering ammonia from an aqueous solution are disclosed. The system includes more than one module arranged in series, each module having more than one membrane, each membrane having a lumen side and a housing side. The more than one module includes a leading module having a housing inlet fluidly connected to a source of aqueous solution, an end module having a lumen inlet fluidly connected to a source of acidic solution, and an optional intermediate module positioned between the leading module and the end module. The method includes directing an aqueous solution to a leading module and an acidic solution to an end module to produce an effluent and a product comprising ammonium.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Serial No. 63 / 451,069, filed on March 9, 2023, entitled “System and Method of Using Gas Permeable Membrane Contactors for the Removal of Ammonia from Wastewater,” which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] Aspects and embodiments disclosed herein relate generally to systems and methods for recovering ammonia, and more particularly, to systems and methods for recovering ammonia from wastewater using gas permeable membrane contactors.

[0004] Overview

[0005] According to one aspect, a system for recovering ammonia from an aqueous solution is provided. The system may include more than one modules arranged in series, each module including more than one membrane, each membrane having a lumen side and a shell side (shell side). More than one module may include a lead module (lead module), which has a housing inlet, a housing outlet, a lumen inlet and a lumen outlet, and the housing inlet is fluidically connected to an aqueous solution source containing ammonia. More than one module may include an end module, which has a lumen inlet, a lumen outlet, a housing inlet and a housing outlet, and the lumen inlet is fluidically connected to an acidic solution source. The housing outlet of the lead module may be fluidically connected to the housing inlet of the end module, and the lumen outlet of the end module may be fluidically connected to the lumen inlet of the lead module.

[0006] In some embodiments, the system also includes 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 leading module, the shell outlet of the intermediate module being fluidly connected to the shell inlet of the terminal module, the lumen inlet of the intermediate module being fluidly connected to the lumen outlet of the terminal module, and the lumen outlet of the intermediate module being fluidly connected to the lumen inlet of the leading module.

[0007] In some embodiments, the aqueous solution is substantially homogeneous.

[0008] In some embodiments, the system can include a temperature control subsystem configured to control the temperature of the aqueous solution.

[0009] In some embodiments, the system can include at least one sensor configured to measure at least one property of the aqueous solution selected from temperature, pH, ammonia concentration, or contaminant concentration.

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

[0011] In some embodiments, the reservoir includes an inlet fluidically connectable to a source of acid, and a discharge outlet.

[0012] In some embodiments, the system can include at least one sensor configured to measure at least one property of the acidic solution selected from temperature, pH, density, specific gravity, conductivity, ammonia concentration, concentration of acid, or ion concentration.

[0013] In some embodiments, the system can include a pH control subsystem configured to control the pH of the acidic solution.

[0014] In some embodiments, the system can include a flow control subsystem configured to control the flow of the aqueous solution.

[0015] In some embodiments, the system can include a flow control subsystem configured to control the flow of the acidic solution.

[0016] In some embodiments, the more than one membrane is hydrophobic, and the module is capable of operating at a temperature of 120 °F - 150 °F.

[0017] According to another aspect, a system for recovering ammonia from an aqueous solution is provided. The system can include more than one row arranged in parallel, each row including more than one module arranged in series, each module including more than one membrane, each membrane having a lumen side and a shell side. Each lead module of the row can have a shell inlet fluidically connected to a source of aqueous solution containing ammonia, a lumen inlet, a shell outlet, and a lumen outlet. Each terminal module of the row can have a lumen inlet fluidically connected to a source of acidic solution, a lumen outlet fluidically connected to the lumen inlet of a corresponding lead module, a shell inlet fluidically connected to the shell outlet of a corresponding lead module, and a shell outlet. The lumen outlet of each lead module can be fluidically connected to the source of acidic solution by a return conduit.

[0018] In some embodiments, each row further includes at least one intermediate module having a housing inlet, a housing outlet, a lumen inlet, and a lumen outlet, the housing inlet of the intermediate module fluidically connected to the housing outlet of the corresponding lead module, the housing outlet of the intermediate module fluidically connected to the housing inlet of the corresponding terminal module, the lumen inlet of the intermediate module fluidically connected to the lumen outlet of the corresponding terminal module, and the lumen outlet of the intermediate module fluidically connected to the lumen inlet of the corresponding lead module.

[0019] In some embodiments, the system can include a pH control subsystem configured to control the pH of the acidic solution.

[0020] In some embodiments, the system can include at least one flow control subsystem configured to control the flow of the acidic solution and / or the aqueous solution source.

[0021] In some embodiments, the system can include a temperature control subsystem configured to control the temperature of the aqueous solution.

[0022] According to another aspect, a method of processing an aqueous solution containing ammonia with a system comprising a plurality of modules is provided, each module comprising a plurality of membranes, each membrane having a lumen side and a housing side. The method can include directing the aqueous solution containing ammonia to a housing inlet of a lead module to produce a first effluent, the first effluent fluidically connected to a housing inlet of a terminal module. The method can include directing an acidic solution to a lumen inlet of the terminal module, the ammonia filtered through the plurality of membranes of the terminal module to produce a first intermediate product containing ammonium, and a second effluent. The first intermediate product can be fluidically connected to a lumen inlet of the lead module, the ammonia filtered through the plurality of membranes of the lead module to produce a second intermediate product containing ammonium.

[0023] In some embodiments, the method can include directing the second intermediate product to a reservoir containing an acid to produce the acidic solution.

[0024] In some embodiments, the method can include controlling the pH of the acidic solution by adding an effective amount of acid.

[0025] In some embodiments, the method can include removing the product containing ammonium from the reservoir.

[0026] In some embodiments, the method can include drying the product containing ammonium to produce a fertilizer product.

[0027] In some embodiments, the method can include directing the second effluent to a point of use.

[0028] In some embodiments, the method can include controlling the temperature of the aqueous solution to be between 95°F and 150°F.

[0029] In some embodiments, the method can include controlling the flow rate of the aqueous solution and the acidic solution.

[0030] The present disclosure contemplates all combinations of any one or more of the foregoing aspects and / or embodiments, as well as combinations with any one or more embodiments and any examples set forth in the detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0032] The drawings are not intended to be to scale. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented with a like numeral. For purposes of clarity, not every component can be called out in every drawing. In the drawings:

[0033] Figure 1 is a block diagram of a system for removing ammonia from an aqueous solution according to an embodiment;

[0034] Figure 2 is a block diagram of an alternative system for removing ammonia from an aqueous solution according to an embodiment;

[0035] Figure 3 is a block diagram of an alternative system for removing ammonia from an aqueous solution according to an embodiment;

[0036] Figure 4 is a block diagram of an alternative system for removing ammonia from an aqueous solution according to an embodiment;

[0037] Figure 5 is a schematic diagram of a system for removing ammonia from an aqueous solution according to an embodiment;

[0038] Figure 6 is a graph showing the percentage of ammonia removal from an aqueous solution according to an embodiment;

[0039] Figure 7 is a graph showing the percentage of ammonia removal from an aqueous solution according to an embodiment; and

[0040] Figure 8 is a graph showing the percentage of ammonia removal from an aqueous solution according to an embodiment.

[0041] DETAILED DESCRIPTION

[0042] The systems and methods disclosed herein can be used to render aqueous solutions, such as wastewater, suitable for secondary use or discharge into the environment. In particular, the systems and methods disclosed herein can be used to reduce the concentration of nitrogen-containing compounds, such as ammonia, from aqueous solutions. According to certain embodiments, the systems and methods disclosed herein can facilitate the 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 can facilitate the recovery of nitrogen-containing compounds in an acidic solution.

[0043] Gas transfer generally involves contacting an aqueous solution with a membrane configured to effect gas-liquid separation by being permeable to gas but not liquid. For example, flowing an aqueous solution within a gas transfer membrane can selectively pass dissolved gas, leaving substantially pure solvent on the filtrate side. The dissolved gas can be absorbed from the feed stream into the acid stream.

[0044] Gas permeable membrane contactors can be used to remove dissolved gas from compatible liquid streams without dispersion. The membrane can be configured to prevent redissolution of gas into the liquid. The membrane contactor, also referred to herein as a "module," can be designed to contain more than one microporous hollow fiber placed within a contactor housing. The hollow fibers can define a lumen side as well as a shell side or housing side. The membranes can be arranged at substantially uniform spacing to allow for high flow capacity and utilization of total membrane surface area. Unlike dispersion phase contactors, such as packed columns, the membrane contactor can provide a constant interfacial area for transfer over a wide range of flow rates. Furthermore, with a hydrophobic membrane, aqueous liquid can be prevented from permeating the membrane pores.

[0045] One exemplary gas transfer membrane module is the Liqui-Cel TM membrane contactor (distributed by 3M TM , Maplewood, MN).

[0046] Systems and methods for treating aqueous solutions to reduce ammonia concentration are disclosed herein. Reducing ammonia concentration can include removing any amount of ammonia from an aqueous stream. Thus, in some embodiments, the ammonia concentration can be reduced by at least 10%, such as 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%. Systems and methods for recovery of ammonia are disclosed herein. Recovery of ammonia can include transferring nitrogen-containing compounds from an aqueous solution into an acidic solution. As used herein, a rate of recovery of ammonia can refer to a rate of transfer of nitrogen-containing compounds. In some embodiments, at least 10% of ammonia, such as 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% of ammonia can be recovered from an aqueous solution.

[0047] The method can include directing an 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 can be directed to a shell inlet of the module. An acidic solution can be directed to a lumen inlet of the module. As the aqueous solution flows along the shell side of the membranes, ammonia is generally filtered through the membranes into the acidic solution that travels through the lumens in a counter-current direction. This reaction can produce an effluent having reduced ammonia that exits through a shell outlet of the module and an intermediate product comprising ammonium that exits through a lumen outlet of the module.

[0048] The membranes can be formed from a hydrophobic material. In some embodiments, the membranes can be formed from a hydrophobic polymeric material or a combination of hydrophobic polymeric materials. Exemplary hydrophobic polymeric materials include polypropylene, polyethylene, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polydimethylsiloxane, polyesters, and polyurethanes. The membranes and / or modules can be capable of operating at high temperatures. In some embodiments, the membranes and / or modules can be capable of operating at temperatures of 95 °F (35 °C) or greater, such as 95 °F (35 °C) - 150 °F (65.55 °C) or 158 °F (70 °C). Thus, in some embodiments, the membranes and / or modules can also be capable of operating at temperatures of 120 °F (48.89 °C) - 150 °F (65.55 °C) or, alternatively, 122 °F (50 °F) - 158 °F (70 °C).

[0049] In some embodiments, the method can be performed with a plurality of modules arranged in series. The aqueous solution can be directed to a shell inlet of a leading module in the series. An acidic solution that generally runs counter-current to the aqueous solution can be directed to an end module in the series, the end module being located opposite or most distal from the leading module in the series. Optionally, one or more intermediate modules can be positioned in series between the leading module and the end module.

[0050] When the aqueous solution is directed to the leading module, an effluent generally having a lower concentration of ammonia can be produced that can exit through a shell outlet of the leading module. The effluent can then be directed to a shell inlet of the next module in the series. Similarly, when the acidic solution is directed to the end module, an intermediate product generally having a higher concentration of ammonium can be produced that can exit through a lumen outlet of the end module. At least a portion of the intermediate product (and, optionally, all of the intermediate product) can then be directed to a lumen inlet of the previous module in the series. In certain embodiments, an optional acidic stream can be combined with the intermediate product upstream of the lumen inlet of the previous module. The lumen inlet and the shell inlet can be positioned on opposite ends of the module. Thus, in operation, the aqueous solution and the acidic solution can run counter-current to one another through the module. The lumen outlet and the shell outlet can also be positioned on opposite ends of the module, each outlet being positioned opposite the respective inlet.

[0051] In certain example embodiments, the acidic solution can include sulfuric acid (H2SO4), which dissociates into hydrogen ions (2H + ) and sulfate ions (SO4 2- ). The hydrogen ions can react with ammonia (NH3(g)) transferred through the membrane to produce ammonium (NH4 + ). In this example embodiment, the ammonium reacts with the sulfate ions to produce ammonium sulfate (NH4)2SO4. Thus, in some embodiments, the intermediate product can include ammonium in the form of ammonium sulfate. In some embodiments, the pH of the acidic solution can be controlled to optimize the efficiency of the acidic solution. In this example embodiment, the pH of the acidic solution can be controlled to be less than about 5.4, such as between about 2-5.4, between about 3-5.4, between about 4-5.4, or between about 5-5.4. In some embodiments, the pH of the acidic solution can be controlled to avoid the production of dihydrogen ions (H2 + ). In this example embodiment, the pH of the acidic solution can be controlled to be less than about 2, such as between about 1.5-2, such as between about 1.5-1.75 or between about 1.75-2, about 1.5, about 1.65, about 1.8, about 1.9, or about 2.

[0052] The present disclosure relates to sulfuric acid as one example acid for ammonia recovery. However, it should be understood that the methods and systems disclosed herein can utilize other acids for effective ammonia recovery. Example acids that can be used in place of sulfuric acid include phosphoric acid, citric acid, and others. Thus, in certain embodiments, the ammonium can react to produce ammonium phosphate, ammonium citrate, or others. The target pH range can be selected in response to the acid. For example, the target pH range can correspond to a pH range in which the acid will effectively re-ionize and absorb ammonia, or the target pH range can correspond to a pH range that avoids the production of dihydrogen ions, as previously described.

[0053] Further, in some embodiments, the temperature of the reaction, e.g., the temperature of the aqueous solution and / or the acidic solution, can be controlled. For example, the temperature of the aqueous solution and / or the acidic solution can be controlled to be greater than about 95 °F (35 °C), e.g., between about 95 °F (35 °C) - 150 °F (65.55 °C) or 158 °F (70 °C), or between about 120 °F (48.89 °C) - 150 °F (65.55 °C) or alternatively 122 °F (50 °F) - 158 °F (70 °C). Elevated temperatures can increase ammonia volatility, thereby increasing reaction efficiency. In some embodiments, the temperature of the acidic solution can be controlled to be equal to or greater than the temperature of the aqueous solution. For example, in some embodiments, the temperature of the acidic solution can be controlled to be equal to the temperature of the aqueous solution or at least 1 °F or at least 0.5 °C greater than the temperature of the aqueous solution, e.g., 0 °F - 1 °F, 0 °F - 5 °F, 1 °F - 10 °F, 1 °F - 20 °F or greater, or 0 °C - 0.5 °C, 0 °C - 2.5 °C, 1 °C - 2.5 °C, 1 °C - 5 °C, 1 °C - 10 °C or greater. While not wishing to be bound by theory, it is believed that controlling this temperature differential can prevent condensation within the module, which is generally undesirable.

[0054] The effluent produced from the aqueous solution after removal of ammonia can be directed to a point of use. The point of use can be associated with an industrial, commercial, or consumer use. The point of use can be associated with microelectronic fabrication, semiconductor fabrication, food and beverage production, food processing (including agricultural uses and irrigation), power and steam generation (including nuclear power generation), petroleum and natural 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.

[0055] In certain example embodiments, the effluent can comprise 155 ppm or less NH3-N (200 mg / L NH4) for an aqueous solution comprising about 6000 ppm ammonia nitrogen (NH3-N). In certain example embodiments, aqueous solutions capable of being treated by the methods disclosed herein can comprise 300 ppm - 8000 ppm NH3-N, e.g., 300 ppm - 500 ppm, 500 ppm - 1000 ppm, 1000 ppm - 2000 ppm, 2000 ppm - 4000 ppm, 4000 ppm - 6000 ppm, or 6000 ppm - 8000 ppm NH3-N. However, aqueous solutions having less than 300 ppm NH3-N can also be capable of being treated by the methods disclosed herein.

[0056] The effluent produced by the systems and methods described herein can have 80-99% less NH3-N than the aqueous solution, such as 80-85% less, 85-90% less, 90-95% less, 95-97% less, or 97-99% less NH3-N. In certain embodiments, at least 80-99% of the ammonia can be recovered from the aqueous solution, such as at least 80-85%, at least 85-90%, at least 90-95%, at least 95-97%, or at least 97-99% of the ammonia can be recovered from the aqueous solution. In some embodiments, the efficiency of ammonia recovery can be at least 50%, such as at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0057] Accordingly, in certain example embodiments, the effluent can comprise a target ammonia concentration of 1 ppm-200 ppm NH3-N, such as a target ammonia concentration of 1 ppm-15 ppm, 15 ppm-25 ppm, 25 ppm-40 ppm, 40 ppm-70 ppm, 70 ppm-100 ppm, 100 ppm-125 ppm, 125 ppm-145 ppm, 145 ppm-155 ppm, 155 ppm-165 ppm, 165 ppm-175 ppm, 175 ppm-185 ppm, or 185 ppm-200 ppm NH3-N. According to certain embodiments, the method can be performed to produce an effluent having less than a threshold concentration of ammonia. The threshold concentration can be between 1 ppm-200 ppm NH3-N, such as 1 ppm, 15 ppm, 25 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 100 ppm, 125 ppm, 135 ppm, 145 ppm, 155 ppm, 165 ppm, 175 ppm, 185 ppm, or 200 ppm NH3-N.

[0058] In some embodiments, the wastewater to be treated, such as raw wastewater, can be directed to a reservoir. Within the reservoir, the wastewater can equilibrate, such as to produce an aqueous solution that is substantially uniform. The reservoir can allow the aqueous solution to be circulated through the module at a constant flow rate and with a substantially consistent composition. The raw wastewater can be associated with an industrial, manufacturing, agricultural, laboratory, or wastewater treatment facility. In certain example embodiments, the raw wastewater can be associated with a biological treatment process, such as a methanogenic treatment process. Accordingly, in some embodiments, the aqueous solution can be substantially uniform.

[0059] The method can include measuring one or more properties of, for example, the aqueous solution, the acidic solution, the acid, the product, the effluent, the intermediate product, or the system. The property can be measured in-line or in the reservoir. The method can include measuring one or more of temperature, pH, pressure, density, specific gravity, conductivity, turbidity, total suspended solids (TSS), total organic carbon (TOC), ammonia concentration (nitrogen concentration), concentration of a contaminant such as an inorganic constituent, or other. Other parameters that can be measured include, but are not limited to, H2O2 concentration, O2 concentration, or CO2 concentration. In certain example embodiments, an inorganic constituent can be measured, for example, to determine whether the concentration can exist at or near a solubility limit. Example inorganic constituents include calcium, magnesium, aluminum, iron, silica, or other.

[0060] In certain example embodiments, the method can include measuring one or more properties of the aqueous solution or the effluent selected from pH, temperature, and saturation level of certain contaminants such as inorganic contaminants. If the contaminant level is too high, the method can include removing the contaminant to avoid or reduce fouling of the membrane and allow effective pH control.

[0061] In certain example embodiments, the method can include measuring one or more properties of the acidic solution or the intermediate product selected from pH, temperature, density, specific gravity, conductivity, concentration of acid, ammonia concentration (nitrogen concentration), or ion concentration, for example, sulfate concentration or phosphate concentration. The method can include adjusting the concentration of acid in the acidic solution in response to the measured property.

[0062] According to certain example embodiments, the method can include measuring or determining ammonia concentration of the raw wastewater or the aqueous solution. In some embodiments, the method can include measuring or determining ammonia concentration of the effluent. The ammonia concentration can be measured with an ammonia nitrogen sensor. In some embodiments, the method can include measuring or determining ammonium concentration of the intermediate product. The ammonium concentration of the intermediate product can be measured or determined by measuring one or more of pH, density, and conductivity of the intermediate product. A correlation can be drawn between the increased ammonium concentration in the intermediate product and the decreased ammonia concentration in the aqueous solution or the effluent. Accordingly, the method can include determining a rate of ammonia recovery from the aqueous solution.

[0063] One or more parameters of the system can be adjusted in response to the ammonia recovery rate. In some embodiments, the flow rate, pH, or temperature can be adjusted to increase or decrease the ammonia recovery rate. For example, the flow rate of one or more of the aqueous solution and the effluent or the acidic solution and the intermediate product can be independently adjusted to increase or decrease the ammonia recovery rate. It is believed that temperature has a direct relationship with the ammonia recovery rate, at least up to a threshold temperature. Thus, it is believed that increasing the temperature will generally increase the ammonia recovery rate up to a target ammonia recovery rate. Additionally, in some embodiments, the pH of the acidic solution can be adjusted to increase or decrease the ammonia recovery rate. For example, the pH of the acidic solution or the aqueous solution can be adjusted to be within a target range (as described in more detail below) to increase the ammonia recovery rate.

[0064] Ammonium produced, for example, by the reactions within the modules, can be used to make ammonium products, such as fertilizer products. For example, ammonium sulfate, ammonium phosphate, ammonium citrate, or other ammonium compounds can be used as fertilizer compositions that include both nitrogen and other compounds, such as sulfur. In some embodiments, the ammonium products can be in the form of liquid fertilizers. In other embodiments, the ammonium products can be crystallized into dry fertilizer forms. For example, in some embodiments, the method can include drying the ammonium products to produce dry fertilizers.

[0065] Thus, in some embodiments, at least a portion of the intermediate product comprising ammonium can be collected as a product and used to make ammonium products, such as fertilizer products. The intermediate product can be collected downstream of the terminal module, for example, downstream of the lumen outlet of the terminal module. The intermediate product can be collected downstream of the intermediate module, for example, downstream of the lumen outlet of the intermediate module. The intermediate product can be collected downstream of the lead module, for example, downstream of the lumen outlet of the lead module.

[0066] In some embodiments, at least a portion of the intermediate product can be recycled to generate the acidic solution. For example, the intermediate product can be directed back to a reservoir used as a source of the acidic solution. Acid can be combined with the intermediate product to produce the acidic solution. The acid can be combined with the intermediate product in an amount effective to maintain a target pH or pH range of the acidic solution. In exemplary embodiments, sulfuric acid can be introduced into the reservoir in an amount effective to maintain a target pH or pH range of the acidic solution. For example, sulfuric acid can be added to the reservoir while an equivalent amount of the acidic solution is purged from the reservoir. In certain embodiments, an exemplary acidic solution can be maintained with less than 35% ammonium sulfate, for example, within 20-35% ammonium sulfate, for example, 20-25%, 25-30%, or 30-35% ammonium sulfate. The acidic solution can be maintained with at least 10% sulfuric acid, for example, within 10-14% sulfuric acid.

[0067] In some embodiments, the product comprising ammonium, such as ammonium sulfate, can be removed from the reservoir. As previously described, the product removed from the reservoir can be used to generate ammonium products, such as fertilizer products. In other embodiments, the product removed from the reservoir can be purged. In some embodiments, the acid and the product are introduced into and removed from the reservoir in a continuous mode. In other embodiments, the acid and the product are introduced into and removed from the reservoir in a batch mode. By producing an acidic solution in the reservoir for recirculation, the solution can reach equilibrium, e.g., the acidic solution can be substantially uniform, allowing the acidic solution to be recirculated through the module at a constant flow rate and at a substantially consistent composition.

[0068] Accordingly, the systems and methods disclosed herein can be used to efficiently produce ammonium products and effluent having a low concentration of ammonia.

[0069] In some embodiments, the flow rate of the aqueous solution and / or the acidic solution can be controlled. The method can include directing the aqueous solution to the module at an exemplary flow rate of between about 150 mL / min - 250 mL / min, such as 150 mL / min - 175 mL / min, 175 mL / min - 185 mL / min, 185 mL / min - 200 mL / min, 200 mL / min - 225 mL / min, or 225 mL / min - 250 mL / min. The method can include directing the acidic solution to the module at a flow rate that is at least 2-10 times faster than the flow rate of the aqueous solution. In some embodiments, the acidic solution can be directed to the module at an exemplary flow rate of between about 1,000 mL / min - 1,500 mL / min, such as 1,000 mL / min - 1,100 mL / min, 1,100 mL / min - 1,200 mL / min, 1,200 mL / min - 1,300 mL / min, 1,300 mL / min - 1,400 mL / min, or 1,400 mL / min - 1,500 mL / min. It will be appreciated that the flow rate can generally be proportional to the module size. Accordingly, higher flow rates (e.g., exemplary flow rates greater than 250 mL / min or 1,500 mL / min) can be used with larger modules.

[0070] Figure 1 is a block diagram of a system 1000 for recovering ammonia from an aqueous solution. The system 1000 can include more than one module, including a lead module 110 and a terminal module 130 positioned in series. In certain embodiments, the system can have 2-5 modules arranged in series, such as 2 modules, 3 modules, 4 modules, or 5 modules. Figure 1The exemplary system 1000 includes one intermediate module 120 positioned between the lead module 110 and the end module 130 , however the system may have no intermediate module 120 or may include more than one intermediate module 120 .

[0071] The system 1000 may include an aqueous solution source 210 fluidly connected to the modules 110, 120, 130 in series. In particular, the aqueous solution source 210 may be directly fluidly connected to the lead module 110. The system 1000 may include an acidic solution source 310 fluidly connected to the modules 110, 120, 130 in series. In particular, the acidic solution source 310 may be directly fluidly connected to the end module 130. In certain embodiments, the acidic solution source 310 may be fluidly connected to another module, for example, the lead module 110 or the intermediate module 120 (in the Figure 1 (shown as dashed lines in FIG). The acidic solution can optionally be directed to another module as needed to control the pH of the acidic solution at the module. Each module 110, 120, 130 can produce an effluent by removing ammonia from the aqueous solution. Each module 110, 120, 130 can produce an intermediate product comprising ammonium.

[0072] The aqueous solution source 210 and / or the acidic solution source 310 may include a reservoir. The system 1000 may produce an effluent, which is optionally directed to the effluent reservoir 220. The system 1000 may include a return line fluidically connecting the modules 110, 120, 130 back to the acidic solution source 310. In certain embodiments, the system 1000 may include one or more draw lines to collect a portion of the intermediate product downstream of the modules 110, 120, 130 and upstream of the acidic solution source 310. The system 1000 may produce a product from the one or more draw lines or from the acidic solution reservoir 310, which is optionally directed to the product reservoir 320. The system 1000 may include an acid source 330 fluidly connected to the acidic solution source 310. The acidic solution source 310 may include a discharge outlet. Figure 1 In the exemplary embodiment of , the discharge outlet is fluidly connected to an optional product reservoir 320. In some embodiments, a source of raw wastewater (not shown) can be fluidly connected to the aqueous solution source 210.

[0073] The aqueous solution source 210 can be fluidly connected to a housing inlet of the lead module 110. The lead module 110 can produce a first effluent from the aqueous solution through the housing side. The housing outlet of the lead module 110 can be fluidly connected to a housing inlet of the intermediate module 120 and the terminal module 130. In the exemplary system 1000, the housing outlet of the lead module 110 is fluidly connected to the housing inlet of the terminal module 130 via the intermediate module 120. Thus, the housing outlet of the lead module 110 can be fluidly connected to direct the first effluent to the housing inlet of the intermediate module 120, while the housing outlet of the intermediate module 120 can be fluidly connected to direct the second effluent to the housing inlet of the terminal module 130. The housing outlet of the terminal module 130 from which a final effluent can be produced can be fluidly connected to the effluent reservoir 220.

[0074] The acidic solution source 310 can be fluidly connected to a lumen inlet of the terminal module 130. The terminal module 130 can produce a first intermediate product through the lumen side. Generally, the acidic solution and the intermediate product can be directed through each module 110, 120, 130 in a counter-current direction opposite the aqueous solution and the effluent. The lumen outlet of the terminal module 130 can be fluidly connected to a lumen inlet of the intermediate module 120 and the lead module 110.

[0075] In the exemplary system 1000, the lumen outlet of the terminal module 130 is fluidly connected to the lumen inlet of the lead module 110 via the intermediate module 120. Thus, the lumen outlet of the terminal module 130 can 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 can be fluidly connected to direct the second intermediate product to the lumen inlet of the lead module 110.

[0076] The lumen outlet of the first module 110 from which a third intermediate product can be produced can be fluidly connected to a product reservoir or the aqueous solution source 310 via a reflux conduit. In some embodiments, as previously described, the intermediate product can be dosed with the acidic solution to control the pH. Further, in some embodiments, at least some of the intermediate product can be drawn between modules to be collected as an ammonia product, such as a fertilizer product.

[0077] In certain embodiments, the system can include more than one row, each row including more than one module. The more than one module in each row can be arranged in series. The more than one row can be arranged in parallel. In certain embodiments, the system can include 2-10 rows, such as 2 rows, 3 rows, 4 rows, 5 rows, 6 rows, 7 rows, 8 rows, 9 rows, or 10 rows. For example, the number of rows can be scaled to include more than 10 rows. Each row can include 2-5 modules in series, as previously described with respect to the exemplary system 1000.

[0078] Figure 2 is a block diagram illustrating an exemplary system 2000 comprising more than one row. The first row of the system 2000 comprises a lead module 110A and a terminal module 130A. The first row of the system 2000 comprises an intermediate module 120A. Each row can be devoid of an intermediate module 120A or comprise more than one intermediate module 120A. The second row of the system 2000 comprises a lead module 110B and a terminal module 130B. The second row of the system 2000 comprises an intermediate module 120B. The number of modules in each row can be the same, as illustrated in the system 2000, or different. Thus, in certain embodiments, the number of modules in each row can be independently selected.

[0079] More than one module 110A, 120A, 130A is arranged in series, as previously described with respect to the system 1000. Further, more than one module 110B, 120B, 130B is arranged in series, as previously described with respect to the system 1000. In the exemplary system 2000, each lead module 110A, 110B is independently fluidically connected to the aqueous solution source 210 through a respective housing inlet. Similarly, in the exemplary system 2000, each terminal module 130A, 130B is independently fluidically connected to the acidic solution source 310 through a respective lumen inlet. In the exemplary system 2000, each terminal module 130A, 130B is fluidically connected to the effluent reservoir 220 through a respective housing outlet. Finally, in the exemplary system 2000, each lead module 110A, 110B is fluidically connected to the acidic solution source 310 through a return conduit fluidically connected to each respective lumen outlet.

[0080] While the exemplary system 2000 comprises a common aqueous solution source 210, acidic solution source 310, and effluent reservoir 220 for all rows, it should be noted that in other embodiments, each row can comprise independent reservoirs for one or more of the aqueous solution source 210, acidic solution source 310, and optional effluent reservoir 220. In other embodiments, a portion of the rows can be fluidically connected to a common reservoir. For example, 2-10 rows can be connected to a common aqueous solution source 210, acidic solution source 310, and / or effluent reservoir 220. In such embodiments, the system can be further scaled up by comprising separate reservoirs for more than one aqueous solution source 210, acidic solution source 310, and / or effluent reservoir 220. The number of rows fluidically connected to each reservoir can be independently selected.

[0081] In some embodiments, the system can include one or more flow control subsystems configured to control the flow of the aqueous solution and / or the acidic solution source. For example, the system can include a flow control subsystem configured and arranged to control the flow of the aqueous solution and the effluent through the module. The system can include a flow control subsystem configured and arranged to control the flow of the acidic solution and the intermediate product through the module. Generally, the flow of the aqueous solution and the effluent can be controlled jointly. Separately and independently, the flow of the acidic solution and the intermediate product can be controlled jointly. The flow control subsystems can be programmed to control the flow within a target flow range as previously described.

[0082] Figure 3 is a block diagram of an exemplary system 3000 including a flow control subsystem. The flow control subsystem includes pump 211 and pump 313. Pump 211 is positioned to control the flow of the aqueous solution and the effluent through the housing side of the module 110, 120, 130. Pump 313 is positioned to control the flow of the acidic solution and the intermediate product through the lumen side of the module 110, 120, 130 in a direction counter-current to the aqueous solution and the effluent. In some embodiments, pump 211 and pump 313 can be operably connected to controller 400. Controller 400 can be programmed to direct pump 211 and / or pump 313 to control the flow of the aqueous solution, the effluent, the acidic solution, and the intermediate product through the module 110, 120, 130.

[0083] In certain embodiments, the flow control subsystem can include one or more flow meters. The flow meters can be positioned to measure the flow of one or more of the aqueous solution, the effluent, the acidic solution, and the intermediate product through the module. The flow meters can be operably connected to one or both of pump 211 and pump 313. Pump 211 or pump 313 can be programmed to control the flow in response to measurements received from the flow meters. In some embodiments, the flow meters and / or the pumps can be operably connected to controller 400. Controller 400 can be programmed to direct one or both of pump 211 and pump 313 to operate in response to measurements received from the flow meters.

[0084] In some embodiments, the system can include one or more temperature control subsystems. The temperature control subsystems can be programmed to control the temperature of the aqueous solution and / or the acidic solution. In some embodiments, the temperature control subsystems can be programmed to control the temperature within a target temperature range as previously described. The temperature control subsystems can additionally or alternatively be programmed to measure the temperature of one or more of the aqueous solution, the effluent, the acidic solution, the intermediate product, or the product. In some embodiments, the temperature control subsystems can be programmed to control the temperature in response to temperature measurements.

[0085] Exemplary system 3000 includes a temperature control subsystem configured to control the temperature of the aqueous solution. In particular, system 3000 includes a heat exchanger 260 positioned to heat or cool the aqueous solution within reservoir 210. Sensor 240 can be configured to measure the temperature of the aqueous solution within reservoir 210. In some embodiments, heat exchanger 260 is operably connected to sensor 240. Heat exchanger 260 can be programmed to control the temperature of the aqueous solution in response to temperature measurements received from sensor 240. In some embodiments, one or both of heat exchanger 260 and sensor 240 can be operably connected to controller 400. Controller 400 can be programmed to direct heat exchanger 260 to control the temperature of the aqueous solution, optionally in response to temperature measurements received from sensor 240.

[0086] While exemplary system 3000 includes a temperature control subsystem configured to control the temperature of the aqueous solution, it will be appreciated that the system can include alternative or additional temperature control subsystems (including heat exchangers and / or temperature sensors) programmed to control the temperature of the acidic solution.

[0087] In some embodiments, the system can include one or more pH control subsystems. The pH control subsystems can include an acid source and / or a base source fluidically connected to the aqueous solution and / or the acidic solution. The pH control subsystems can be programmed to control the pH of the aqueous solution and / or the acidic solution. In some embodiments, the pH control subsystems can be programmed to control the pH within a target pH range as previously described. The pH control subsystems can additionally or alternatively be programmed to measure the pH of one or more of the aqueous solution, the effluent, the acidic solution, an intermediate product, or a product. In some embodiments, the pH control subsystems can be programmed to control the pH in response to pH measurements.

[0088] Exemplary system 3000 includes a pH control subsystem configured to control the pH of the acidic solution. The pH control subsystem includes an acid source 330 and valves 331, 312. Valve 331 is positioned to control the flow of acid from reservoir 330 into the acidic solution reservoir 310. Valve 312 is positioned to control the flow of the acidic solution from reservoir 310 through the drain outlet to the optional product reservoir 320. Valves 331, 312 can be programmed to introduce acid and remove the acidic solution to maintain a target pH range within reservoir 310. Sensor 340 can be configured to measure the pH of the acidic solution within reservoir 310. In some embodiments, valves 331, 312 can be operably connected to sensor 340. Valves 331, 312 can be programmed to actuate in response to pH measurements received from sensor 340. In some embodiments, one or more of valve 331, valve 312, and sensor 340 can be operably connected to controller 400. Controller 400 can be programmed to direct valves 331, 312 to control the pH of the acidic solution, optionally in response to pH measurements received from sensor 340.

[0089] While exemplary system 3000 includes a pH control subsystem configured to control the pH of the acidic solution, it should be understood that the system can include alternative or additional pH control subsystems (including an acid source or a base source, one or more valves, and / or a pH sensor) programmed to control the pH of the aqueous solution. For example, the system can include a base source fluidically connected to the aqueous solution. In certain exemplary embodiments, the base can include sodium hydroxide (NaOH), as shown in Figure 5 Figure 5

[0090] The system can 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. Sensors 240, 340, 250, 350 can 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 a constituent, e.g., a concentration of one or more compounds. It should be understood that sensors 240, 340, 250, 350 can be formed from a single sensor or multiple sensors, optionally each configured to measure a different parameter.

[0091] While the exemplary sensors 240, 340, 250, 350 of the system 3000 are shown as being in communication with the reservoirs 210, 310, 220, 320, respectively, it should be understood that one or more of the sensors 240, 340, 250, 350 can be positioned in-line communication with the associated conduit. Further, the system can include sensors positioned to measure parameters of intermediate products. Sensors configured to measure parameters of intermediate products can be in communication with a reservoir containing the intermediate product or in-line communication with an intermediate product return conduit.

[0092] Accordingly, in some embodiments, the system can include a controller 400. The controller can be operably connected to one or more flow control subsystems, such as one or both of the pumps 211 and 313. The controller 400 can be operably connected to a temperature control subsystem, such as the heat exchanger 260. The controller 400 can be operably connected to a pH control subsystem, such as one or both of the valves 331 and 312. Accordingly, the controller 400 can be programmed to control one or more of the flow, temperature, and pH within the system. In some embodiments, the controller 400 can be operably connected to one or more of the sensors 240, 340, 250, and 350. The controller 400 can be programmed to control one or more of the flow, temperature, and pH in response to measurements received from one or more of the sensors 240, 340, 250, and 350. The controller 400 can be connected to one or more components through a wireless connection. For example, the controller can be connected through a wireless local area network (WLAN) or short wavelength ultra high frequency (UHF) radio waves.

[0093] The controller 400 can be associated with one or more processors that are typically connected to one or more memory devices. The memory devices can be used to store programs and data during operation of the system. For example, the memory devices can be used to store historical data related to parameters over a period of time, as well as operational data. In some embodiments, the controller 400 disclosed herein can be operably connected to external data storage. For example, the controller 400 can be operably connected to an external server and / or cloud data storage. Accordingly, the controller 400 can be configured to transmit data to memory storage or cloud-based memory storage. Such data can include, for example, operational parameters, measurements, and / or status indicators of the components of the system.

[0094] The stored data can be accessed by a computer or mobile device. In some embodiments, the controller 400 or processor associated with the memory can be configured to notify a user of operational parameters, measurements, and / or status of system components. For example, notifications can be pushed to a computer or mobile device to notify a user. Operational parameters and measurements include, for example, properties of aqueous solutions, acidic solutions, effluent, intermediates, or products. Status of system components can include, for example, status of one or more sensors, pumps, or valves, such as whether the system component is offline (disconnected from the controller 400), whether it has lost power, whether it requires adjustment, whether it requires maintenance (scheduled or unscheduled), and / or fill level of a reservoir. However, notifications can relate to any operational parameter, measurement, or status of system components disclosed herein. In certain embodiments, information such as system updates can be communicated to the controller 400 from an external source.

[0095] The controller 400 can also be configured to access data from a memory storage device or cloud-based memory. The controller 400 can be programmed to predict operation of the system based on historical data stored in the memory. For example, the controller 400 can be programmed to predict future adjustments required for flow control, temperature control, or pH control based on currently measured parameters and historical data. The controller 400 can additionally be programmed to predict whether a system component will require adjustment or maintenance based on currently measured parameters and historical data. In some embodiments, one or more of the processes disclosed herein can be performed manually or semi-automatically.

[0096] In some embodiments, the system can include one or more manifolds configured to distribute fluid streams. Figure 4 is a block diagram illustrating an exemplary system 4000 including a first row of modules 110A, 120A, 130A and a second row of modules 110B, 120B, 130B. The exemplary system 4000 includes manifolds 115, 215, 315 positioned to distribute fluid streams. In particular, the manifold 115 is positioned to integrate a first intermediate product from the module 110A and a second intermediate product from the module 110B into a reflux conduit that is directed to the acidic solution reservoir 310. The manifold 215 is positioned to distribute aqueous solution from the aqueous solution source 210 to the module 110A and the module 110B. The manifold 315 is positioned to distribute acidic solution from the acidic solution source 310 to the module 130A and the module 130B. The manifolds 115, 215, 315 can be operably connected to the controller 400. Thus, in some embodiments, the controller 400 can be programmed to control distribution of one or more flow streams within the system by actuating one or more of the manifolds 115, 215, and 315.

[0097] In some embodiments, one or more separation devices or filters, such as a cartridge filter Figure 5 ), can 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 example, the separation device or filter can be positioned to separate contaminants that can otherwise collect on the membrane or form scale. In certain example embodiments, the filter can be a 5 micron cartridge filter. The separation device or filter can be positioned downstream of the aqueous solution source or downstream of the acidic solution source. In some embodiments, the separation device or filter can be positioned downstream of the housing outlet of the terminal module. In some embodiments, the separation device or filter can be positioned downstream of the lumen outlet of the lead module. In some embodiments, the separation device or filter can be positioned downstream of the drain outlet of the acidic solution source.

[0098] In some embodiments, the system can include a catalyst source, such as a hydrogen peroxide (H2O2) destruction catalyst, fluidly connected to the aqueous solution source or the effluent. An example catalyst is optimase Figure 5 For semiconductor manufacturing systems, the H2O2 destruction catalyst can facilitate degradation of H2O2 in the aqueous solution or effluent.

[0099] Figure 5 is a schematic of a benchtop system for recovering ammonia from an aqueous solution, as used in the testing of the examples below. Figure 5 The system of FIG. 1 includes a feed source of an aqueous solution containing ammonia. For the purposes of the benchtop experiments, the aqueous solution is optionally spiked with ammonium sulfate ((NH4)2SO4) and hydrogen peroxide (H2O2). An optimase and sodium hydroxide (NaOH) are fluidly connected to the raw wastewater maintained in a feed tank at 95 °F (35 °C). A first pump directs the aqueous solution to a cartridge filter positioned upstream of a 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 includes a respective sampling valve. An effluent tank is positioned downstream of module C. A recirculation conduit connects module B and module C to a tank storing an acidic solution. Sulfuric acid (H2SO4) is directed to the acidic solution tank, which is also maintained at 95 °F (35 °C). A second pump directs the acidic solution to a cartridge filter positioned upstream of the modules arranged in parallel with respect to the acidic solution. Examples

[0100] The function and advantages of these and other embodiments will be more fully understood from the following examples. These examples are intended to be illustrative only and are not intended to limit the scope of the present application.

[0101] Example 1 : Bench test using aqueous solution spiked with ammonium sulfate ((NH4)2SO4)

[0102] Preparation of aqueous solution

[0103] An aqueous solution (60 L) was prepared by spiking a sample of ammonium sulfate (758 g at 12.6 g / L) to more closely resemble the maximum ammonia concentration in 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, which is equivalent to about 6,000 mg / L NH4 + . However, the actual ammonia concentration in the feed aqueous solution was determined to be 4,181 mg / L N after analysis.

[0104] Preparation of acidic solution

[0105] An acidic solution (19 L) was prepared by dosing a synthetic ammonium sulfate solution from a previous test (to resemble steady state operating conditions) in combination with sulfuric acid (0.95 g / L) to achieve a pH of 1.65.

[0106] Operating parameters

[0107] The example system was operated according to the parameters shown in Table 1 below Figure 5 . The module was a Liqui-Cel TM membrane contactor (distributed by 3M TM , Maplewood, MN) having dimensions of 2.5 diameter x 8 length and a membrane contact area of 6 ft 2 . The cartridge filter was a 5 micron cartridge filter.

[0108] Table 1 : Operating parameters

[0109]

[0110] The pilot unit processed about 46 liters of aqueous solution over a period of 4 hours. Operational data was collected and grab samples were taken from the reservoir every 30 minutes.

[0111] Test results

[0112] The results are presented in Table 2 below and Figure 6 in the figures.

[0113] Table 2: Test results for bench test using ammonium sulfate

[0114]

[0115] * Percent by weight based on ammonia analysis

[0116] Cumulative dose of make-up H2SO4 to maintain pH 1.7 in acidic solution

[0117] As shown in Table 2, 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). Thus, the membrane contactor pilot unit met the effluent quality target of 155 mg / L NH3-N (200 mg / L NH4). Table 2 also shows that as the ammonia concentration in the acidic solution tank increased from 17,804 mg / L N to 27,036 mg / L N, fluoride was rejected by the membrane ( < 0.2 mg / L F in the final acidic solution).

[0118] The 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 acidic scrubbing solution. Table 2 shows that the ammonia concentration increased by 9,232 mg / L NH3-N, which is 93% of the expected recovery.

[0119] The alkalinity of the effluent and the acidity of the acidic solution stream immediately downstream of the lead module were determined to be sufficient to remove ammonia from the aqueous solution. As shown in the graph of Figure 6 As shown in the graph of

[0120] Thus, under the parameters of the test, the bench system was able to meet the 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 showed the ability of the system to remove ammonia from the aqueous solution while utilizing the counter-currently recycled acidic solution at steady state with the addition of sulfuric acid as needed to maintain the desired pH range.

[0121] Example 2: Bench test using aqueous solution without ammonium sulfate ((NH4)2SO4)

[0122] A second test was conducted under the same conditions as Example 1 and using the example system of Figure 5 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 (in a similar manner to the steady state operating conditions) with an effective amount of sulfuric acid to achieve a pH of 1.65.

[0123] Test Results

[0124] Results are summarized in Table 3 below andFigure 7 is presented in the figure.

[0125] Table 3: Test results for benchtop testing without ammonium sulfate

[0126]

[0127] *Percentages by weight based on ammonia analysis

[0128] **Cumulative dose of supplemental H2SO4 to maintain pH 1.7 in acidic solution

[0129] As shown in Table 3, the membrane contactor unit removed 97.8% of ammoniacal nitrogen from an aqueous solution containing 1,910 mg / L NH3-N and produced an effluent containing 41 mg / L NH3-N (53 mg / L NH4). The membrane contactor pilot unit met the effluent quality target of 155 mg / L NH3-N (200 mg / L NH4). Table 3 also shows that as the ammonia concentration in the acid solution tank increased from 28,838 mg / LN to 31,807 mg / LN, all fluoride was rejected by the membrane (<0.2 mg / LF in the final acid solution).

[0130] A 97.8% ammonia recovery efficiency from 46 liters of aqueous solution containing 1,910 g / L NH3-N would be expected if 4,608 mg / L NH3-N were added to 18.9 liters of acidic scrubbing solution. However, Table 3 shows that the ammonia concentration in the acidic solution increased by 2,972 mg / L NH3-N, which is only 64% of the expected recovery.

[0131] The alkalinity of the effluent and the acidity of the acid solution stream immediately downstream of the lead module were determined to be sufficient to remove ammonia from the aqueous solution. Figure 7 As shown in the figure, the ammonia removal percentages of the three membrane contactor modules were relatively stable over the time period tested. The average ammonia removal rates of the leading module, the middle (middle) module, and the tail (last) module were 73%, 76%, and 64%, respectively.

[0132] Thus, under the parameters of the second test, the benchtop system was able to meet the target final ammonia concentration in the effluent tank of 200 mg / L NH4 or less (the actual final ammonia concentration was 53 mg / L NH4). This test demonstrates the system's ability to remove ammonia from an aqueous solution (having a lower ammonia nitrogen concentration) while utilizing a countercurrent recirculating acidic solution at steady state with the addition of sulfuric acid as needed to maintain the desired pH range.

[0133] Example 3: Benchtop testing using aqueous and acidic solutions spiked with ammonium sulfate ((NH4)2SO4)

[0134] A third test was conducted under the same conditions as Example 1 and using the exemplary system of Figure 5 The aqueous solution had an actual ammonia concentration of 4,653 mg / L N. The acidic solution was prepared by adding ammonium sulfate to the remaining acidic solution from Example 2 to achieve 25% (2,328 g (NH4)2S04(123 g / L)) and dosing the solution with an effective amount of sulfuric acid to achieve a pH of 1.65. The ammonium sulfate in the acidic solution increased from 25.5% to 31.8% over the course of the test.

[0135] Test Results

[0136] Results are presented in Table 4 below and in the graph of Figure 8

[0137] Table 4: Test results for bench test with ammonium sulfate in aqueous and acidic solutions

[0138]

[0139] * Percent by weight based on ammonia analysis

[0140] ** Cumulative dose of supplemental H2S04to maintain pH 1.7 in acidic solution

[0141] As shown in Table 4, 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 the effluent quality target of 155 mg / L NH3-N (200 mg / L NH4). Table 4 also shows that as the ammonia concentration in the acidic solution tank increased from 62,088 mg / L N to 79,627 mg / L N, all of the fluoride was rejected by the membrane ( < 0.2 mg / L F in the final acidic solution).

[0142] The data in Table 4 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 is likely due to the error in the initial ammonia reading and the final ammonia reading in the acidic solution tank being as little as 4%, which is an acceptable analytical error.

[0143] The alkalinity of the effluent and the acidity of the acidic solution stream immediately downstream of the lead module were determined to be sufficient to remove ammonia from the aqueous solution. As shown in the graph of Figure 8 The percent ammonia removal for the three membrane contactor modules was relatively stable over the time period of the test. The average ammonia removal for the lead module, the middle (mid-section) module, and the end (last) module was 72%, 66%, and 68%, respectively. ​

[0144] Thus, under the parameters of the third test, the bench-scale system was able to meet the target final ammonia concentration in the effluent tank of 200 mg / L NH4or less (actual final ammonia concentration was 186 mg / L NH4). This test showed the ability of the system to remove ammonia from an aqueous solution while utilizing an acidic solution (with greater ammonium concentration) in counter-current recycle at steady state with the addition of sulfuric acid as needed to maintain the desired pH range.

[0145] 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" means two or more items or components. The terms "comprising," "including," "carrying," "having," "containing," and "involving," regardless of whether they are in the detailed description or the claims, are open-ended terms that is, they mean "including, but not limited to." Thus, use of such terms indicates that the inclusion of items in the list is not a complete listing of the items, and that additional items are contemplated. With respect to the claims, only the transitional phrases "consisting of and "consisting essentially of are closed transitional phrases, or semi-closed transitional phrases, respectively. The 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 temporal sequence of actions in a method, but rather merely makes for ease of identification purposes, and is not limiting as to a limitation of elements.

[0146] Having thus described several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment can be included in or substituted for any other embodiment in any combination. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the application. Accordingly, the foregoing description and drawings are by way of example only.

[0147] Those skilled in the art will 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 will further appreciate that the disclosed specific embodiments can be readily adapted for use with other applications.

Claims

1. A system for recovering ammonia from an aqueous solution, comprising: more than one module arranged in series, each module comprising more than one membrane, each membrane having a lumen side and a shell side, The more than one modules include a lead module having a housing inlet, a housing outlet, a lumen inlet, and a lumen outlet, the housing inlet being fluidly connected to a source of an aqueous solution comprising ammonia, The more than one modules include an end module having a lumen inlet, a lumen outlet, a housing inlet, and a housing outlet, the lumen inlet being fluidly connected to a source of acidic solution, The housing outlet of the lead module is fluidly connected to the housing inlet of the end module, and the lumen outlet of the end module is fluidly connected to the lumen inlet of the lead module.

2. The system according to claim 1 further includes at least one intermediate module, wherein the intermediate module has a shell inlet, a shell outlet, a lumen inlet and a lumen outlet, the shell inlet of the intermediate module is fluidly connected to the shell outlet of the leading module, the shell outlet of the intermediate module is fluidly connected to the shell inlet of the terminal module, the lumen inlet of the intermediate module is fluidly connected to the lumen outlet of the terminal module, and the lumen outlet of the intermediate module is fluidly connected to the lumen inlet of the leading module.

3. The system of claim 1, wherein the aqueous solution is substantially homogeneous. 4 . The system of claim 3 , further comprising a temperature control subsystem configured to control the temperature of the aqueous solution.

5. The system of claim 3, further comprising at least one sensor configured to measure at least one property of the aqueous solution selected from temperature, pH, ammonia concentration, or contaminant concentration.

6. The system of claim 6, wherein the lumen outlet of the lead module is fluidly connected to a reservoir containing the source of the acidic solution via a return line.

7. The system of claim 6, wherein the reservoir comprises an inlet fluidly connectable to an acid source, and a discharge outlet.

8. The system of claim 7, further comprising at least one sensor configured to measure at least one property of the acidic solution selected from temperature, pH, density, specific gravity, conductivity, ammonia concentration, acid concentration, or ion concentration.

9. The system of claim 7, further comprising a pH control subsystem configured to control the pH of the acidic solution.

10. The system of claim 1, further comprising a flow control subsystem configured to control the flow of the aqueous solution.

11. The system of claim 1 , further comprising a flow control subsystem configured to control a flow of the acidic solution.

12. The system of claim 1, wherein the more than one membrane is hydrophobic and the module is capable of operating at a temperature of 120°F - 150°F.

13. A system for recovering ammonia from an aqueous solution, comprising: more than one row arranged in parallel, each row comprising more than one module arranged in series, each module comprising more than one membrane, each membrane having a lumen side and a shell side, Each lead module of the row has a housing inlet, a lumen inlet, a housing outlet, and a lumen outlet, the housing inlet being fluidly connected to a source of an aqueous solution containing ammonia, Each end module of the row has a lumen inlet fluidly connected to a source of acidic solution, a lumen outlet fluidly connected to the lumen inlet of a corresponding lead module, a housing inlet fluidly connected to the housing outlet of the corresponding lead module, and a housing outlet, The lumen outlet of each lead module is fluidly connected to the acidic solution source via a return conduit.

14. The system of claim 13 , wherein each row further comprises at least one intermediate module, the 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 corresponding leading module, the shell outlet of the intermediate module being fluidly connected to the shell inlet of the corresponding end module, the lumen inlet of the intermediate module being fluidly connected to the lumen outlet of the corresponding end module, and the lumen outlet of the intermediate module being fluidly connected to the lumen inlet of the corresponding leading module.

15. The system of claim 13, further comprising a pH control subsystem configured to control the pH of the acidic solution.

16. The system of claim 13, further comprising at least one flow control subsystem configured to control the flow of the acidic solution and / or the aqueous solution source.

17. The system of claim 13, further comprising a temperature control subsystem configured to control the temperature of the aqueous solution.

18. A method of treating an aqueous solution containing ammonia using a system comprising more than one module, each module comprising more than one membrane, 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, which is fluidly connected to a shell inlet of a terminal module, directing an acidic solution to a lumen inlet of the end module, the ammonia being filtered through the more than one membrane of the end module to produce a first intermediate product comprising ammonium, and a second effluent, The first intermediate product is fluidly connected to a lumen inlet of the lead module, and the ammonia is filtered through the more than one membranes of the lead module to produce a second intermediate product comprising ammonium.

19. The method of claim 18, further comprising directing the second intermediate product to a reservoir containing an acid to produce the acidic solution.

20. The method of claim 19, further comprising controlling the pH of the acidic solution by adding an effective amount of the acid.

21. The method of claim 19, further comprising removing the product comprising ammonium from the reservoir.

22. The method of claim 21, further comprising drying the ammonium-containing product to produce a fertilizer product.

23. The method of claim 18, further comprising directing the second effluent to a point of use.

24. The method of claim 18, further comprising controlling the temperature of the aqueous solution to between 95°F and 150°F.

25. The method of claim 18, further comprising controlling the flow rates of the aqueous solution and the acidic solution.

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