SYSTEM AND METHODS OF REMOVING IONS FROM DRAINAGE WATER

Abstract

An ion exchange system includes a first ion exchange column containing a first resin having an affinity for sulfate ions and nitrate ions that is greater than the first resin's affinity for chloride ions. The first ion exchange column is configured to pass a predetermined mass flow rate of drainage water therethrough. A second ion exchange column is connected in series with the first ion exchange column. The second ion exchange column contains a second resin having an affinity for chloride ions and is configured to pass the same predetermined mass flow rate of the same drainage water therethrough. As the drainage water passes through the first ion exchange column, primarily sulfate ions and/or nitrate ions are removed from the drainage water. As the drainage water passes through the second ion exchange column, primarily chloride ions are removed from the drainage water.

Claims

1. An ion exchange system comprising: a first ion exchange column containing a first resin having an affinity for sulfate ions and nitrate ions that is greater than the first resin's affinity for chloride ions, the first ion exchange column configured to pass a predetermined mass flow rate of drainage water therethrough, the drainage water having chloride ions and at least one of sulfate ions and nitrate ions contained therein; and a second ion exchange column connected in series fluid communication with the first ion exchange column, the second ion exchange column containing a second resin having an affinity for chloride ions, the second ion exchange column configured to pass the same predetermined mass flow rate of the same drainage water therethrough; wherein, as the drainage water passes through the first ion exchange column, primarily the at least one of the sulfate ions and nitrate ions are removed from the drainage water and exchanged for first ions in the first resin; and wherein, as the drainage water passes through the second ion exchange column, primarily chloride ions are removed from the drainage water and exchanged for second ions in the second resin.

2. The ion exchange system of claim 1, comprising: the first ion exchange column having a first geometry that induces a first fluid velocity of the drainage water through the first ion exchange column, and the second ion exchange column having a second geometry that induces a second fluid velocity of the drainage water through the second ion exchange column, the second fluid velocity being less than the first fluid velocity.

3. The ion exchange system of claim 2, wherein the second fluid velocity is about one third to two thirds the first fluid velocity.

4. The ion exchange system of claim 1, wherein the second resin has an affinity for sulfate ions and nitrate ions that is greater than the second resin's affinity for chloride ions.

5. The ion exchange system of claim 1, wherein the first resin and the second resin are substantially the same resin.

6. The ion exchange system of claim 1, wherein: the first ions in the first resin comprise bicarbonate ions that are exchanged for the at least one of the sulfate ions and nitrate ions as the drainage water passes through the first ion exchange column; and the second ions in the second resin comprise bicarbonate ions that are exchanged for the chloride ions as the drainage water passes through the second ion exchange column.

7. The ion exchange system of claim 1: a bicarbonate removal tank configured to receive the drainage water that is discharged from the second ion exchange column; and and acid injection system configured to inject acid into the bicarbonate removal tank to convert bicarbonate ions (HCO.sub.3) contained in the drainage water into carbon dioxide (CO.sub.2).

8. The ion exchange system of claim 1, comprising a regeneration system for regenerating the first ions in the first resin and the second ions in the second resin with bicarbonate ions after the drainage water has passed through the first and second ion exchange columns, the regeneration system comprising: a first tank configured to contain a regenerate solution of ammonium bicarbonate, the first tank in selective fluid communication with a first three-way valve; a second tank configured to contain fresh water, the second tank in selective fluid communication with the first three-way valve; a first pump having an intake port in fluid communication with the first three-way valve; a second three-way valve in fluid communication with an output port of the first pump and in selective fluid communication with the first and second ion exchange columns; wherein, the first and second three-way valves are operable to selectively provide fluid communication between: the first tank and the first ion exchange column, the first tank and the second ion exchange column, the second tank and the first ion exchange column, and the second tank and the second ion exchange column.

9. The ion exchange system of claim 8, wherein the regeneration system is operable to: pump, via the first pump, the regenerate solution at a first flow rate from the first tank through the first ion exchange column in a reverse flow direction relative to the flow of drainage water, and collect a resulting nutrient brine from the first ion exchange column in a nutrient brine tank; pump, via the first pump, the fresh water at a second flow rate from the second tank through the first ion exchange column in the reverse flow direction, and collect a resulting first water effluent from the first ion exchange column in the nutrient brine tank, wherein the second flow rate is faster than the first flow rate; pump, via the first pump, the regenerate solution at a third flow rate from the first tank through the second ion exchange column in the reverse flow direction, and collect a resulting chloride brine from the second ion exchange column in a chloride brine tank; and pump, via the first pump, the fresh water at a fourth flow rate from the second tank through the second ion exchange column in the reverse flow direction, and collect a resulting second water effluent from the first ion exchange column in the chloride brine tank, wherein the fourth flow rate is faster than the third flow rate.

10. The ion exchange system of claim 9, wherein the regeneration system comprises a chloride brine processing system, the chloride brine processing system comprising: a second pump configured to pump the chloride brine from the chloride brine tank to a first holding tank; a lime injection system configured to inject lime into the first holding tank to raise the pH of the chloride brine to about 12 and to convert the ammonium (NH.sub.4) in the chloride brine to ammonia (NH.sub.3) gas; an ammonia collection tank configured to collect the ammonia gas; and a third pump configured to pump the ammonia gas into the first tank of the regeneration system to be incorporated into the regenerate solution of ammonium bicarbonate in the first tank.

11. The ion exchange system of claim 10, wherein the chloride brine processing system further comprises: a sodium aluminate injection system configured to inject sodium aluminate into the first holding tank to form a calcium-aluminum-chloride based Friedel's salt; an anionic polyacrylamide (PAM) injection system configured to inject PAM into the first holding tank to result in a suspension of solids and supernatant; and a fourth pump configured to pump the suspension into an at least one settling tank; an acid injection system configured to inject acid into the at least one settling tank to reduce the pH of the suspension to about 7 and to convert bicarbonate ions (HCO.sub.3) into carbon dioxide (CO.sub.2); wherein the at least one settling tank is configured to enable the solids of the suspension to be drained off of the bottom of the at least one settling tank.

12. The ion exchange system of claim 9, wherein the regeneration system comprises a chloride brine processing system, the chloride brine processing system comprising: a mixing tank containing calcinated hydrotalcite, wherein the calcinated hydrotalcite is operable to absorb the chloride from the chloride brine of the chloride brine tank.

13. The ion exchange system of claim 9, wherein the regeneration system comprises a chloride brine processing system, the chloride brine processing system comprising: an acid injection system configured to inject an acid into the chloride brine of the chloride brine tank to convert bicarbonate (HCO.sub.3) of the chloride brine into carbon dioxide (CO.sub.2) and leaving an ammonium based liquid fertilizer.

14. A method of removing ions from drainage water, the method comprising: passing drainage water having chloride ions and at least one of sulfate ions and nitrate ions through a first ion exchange column at a predetermined mass flow rate, the first ion exchange column containing a first resin having an affinity for sulfate ions and nitrate ions that is greater than the first resin's affinity for chloride ions; exchanging bicarbonate ions in the first resin with primarily the at least one of sulfate ions and nitrate ions in the drainage water; passing the drainage water through a second ion exchange column at the same predetermined mass flow rate, the second ion exchange column containing a second resin having an affinity for chloride ions; and exchanging bicarbonate ions in the second resin with primarily the chloride ions in the drainage water.

15. The method of claim 14, comprising: passing the drainage water through the first ion exchange column at a first fluid velocity; and passing the drainage water through the second ion exchange column at a second fluid velocity, wherein the second fluid velocity is less than the first fluid velocity.

16. The method of claim 14, comprising: pumping the drainage water from the second ion exchange column into a bicarbonate removal tank; and injecting acid into the bicarbonate removal tank to convert bicarbonate ions (HCO.sub.3) contained in the drainage water into carbon dioxide (CO.sub.2).

17. The method of claim 14, comprising: pumping a regenerate solution of ammonium bicarbonate at a first flow rate through the first ion exchange column in a reverse flow direction relative to the flow of drainage water, and collecting a resulting nutrient brine from the first ion exchange column in a nutrient brine tank; pumping fresh water at a second flow rate through the first ion exchange column in the reverse flow direction, and collecting a resulting first water effluent from the first ion exchange column in the nutrient brine tank, wherein the second flow rate is faster than the first flow rate; pumping the regenerate solution at a third flow rate through the second ion exchange column in the reverse flow direction and collecting a resulting chloride brine from the second ion exchange column in a chloride brine tank; and pumping fresh water at a fourth flow rate through the second ion exchange column in the reverse flow direction, and collecting a resulting second water effluent from the second ion exchange column in the chloride brine tank, wherein the fourth flow rate is faster than the third flow rate.

18. The method of claim 17, comprising: injecting lime into the chloride brine tank to raise the pH of the chloride brine to about 12 and to convert the ammonium (NH.sub.4) in the chloride brine to ammonia (NH.sub.3) gas; collecting the ammonia gas; and pumping the collected ammonia gas into the regenerate solution of ammonium bicarbonate.

19. The method of claim 18, comprising: injecting sodium aluminate into the chloride brine tank to form a calcium-aluminum-chloride based Friedel's salt; injecting an anionic polyacrylamide into the chloride brine tank to form a suspension of solids and supernatant; pumping the suspension into an at least one settling tank; injecting acid into the at least one settling tank to reduce the pH of the suspension to about 7 and to convert bicarbonate ions (HCO.sub.3) into carbon dioxide (CO.sub.2); and draining the solids of the suspension off of the bottom of the at least one settling tank.

20. The method of claim 17, comprising: mixing the chloride brine of the chloride brine tank with calcinated hydrotalcite, wherein the calcinated hydrotalcite is operable to absorb the chloride from the chloride brine of the chloride brine tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0020] FIG. 1 depicts an example of a schematic view of an ion exchange system having a first ion exchange column in series fluid communication with a second ion exchange column to remove ions from a flow of drainage water, according to aspects described herein;

[0021] FIG. 2 depicts an example of a schematic view of the ion exchange system of FIG. 1 wherein acid is injected into the drainage water that is discharged from the second ion exchange column to convert bicarbonate into carbon dioxide prior to irrigation.

[0022] FIG. 3 depicts an example of a schematic view of a regeneration system associated with the ion exchange system of FIG. 1, according to aspects described herein;

[0023] FIG. 4 depicts an example of a schematic view of a brine processing system associated with the regeneration system of FIG. 3, according to aspects described herein;

[0024] FIG. 5 depicts an example of a schematic view of another brine processing system associated with the regeneration system of FIG. 3, according to aspects described herein;

[0025] FIG. 6 depicts an example of a schematic view of another brine processing system associated with the regeneration system of FIG. 3, according to aspects described herein;

[0026] FIG. 7 depicts a flow diagram of a method of removing ions from drainage water, using a first ion exchange column in series fluid communication with a second ion exchange column, according to aspects described herein;

[0027] FIG. 8 depicts a flow diagram of a method of regenerating the first and second ion columns of FIG. 7, wherein nutrient brine from the first ion exchange column is pumped into a nutrient tank and chloride brine from the second ion exchange column is pumped into a chloride brine tank, according to aspects described herein;

[0028] FIG. 9 depicts a flow diagram of a method of processing the chloride brine tank of FIG. 8, according to aspects described herein;

[0029] FIG. 10 depicts a flow diagram of another method of processing the chloride brine tank of FIG. 8, according to aspects described herein; and

[0030] FIG. 11 depicts a flow diagram of another method of processing the chloride brine tank of FIG. 8, according to aspects described herein.

DETAILED DESCRIPTION

[0031] Certain examples will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the methods, systems, and devices disclosed herein. One or more examples are illustrated in the accompanying drawings. Those skilled in the art will understand that the methods, systems, and devices specifically described herein and illustrated in the accompanying drawings are non-limiting examples and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in connection with one example may be combined with the features of other examples. Such modifications and variations are intended to be included within the scope of the present disclosure.

[0032] The terms significantly, substantially, approximately, about, relatively, or other such similar terms that may be used throughout this disclosure, including the claims, are used to describe and account for small fluctuations, such as due to variations in processing from a reference or parameter. Such small fluctuations include a zero fluctuation from the reference or parameter as well. For example, they can refer to less than or equal to 10%, such as less than or equal to 5%, such as less than or equal to 2%, such as less than or equal to #1%, such as less than or equal to 0.5%, such as less than or equal to 0.2%, such as less than or equal to 0.1%, such as less than or equal to 0.05%.

[0033] Referring to FIG. 1, an example is depicted of a schematic view of an ion exchange system 100 having a first ion exchange column 102 in series fluid communication with a second ion exchange column 104 to remove ions from a flow of drainage water 106, according to aspects described herein. The drainage water 106 may be irrigation water that is used to irrigate crops in an agricultural system and then drained through an agricultural drainage system. Such drainage water often contains chloride ions, sulfate ions and/or nitrate ions that should be separated from the drainage water before being returned to the local ecosystem.

[0034] The ion exchange system 100 may included a drainage water pump 108, which may pump the drainage water 106 through a sediment filter 110 at a predetermined mass flow rate, wherein the mass flow rate may be considered to be the mass of drainage water that passes through an area per unit of time. From the sediment filter 110, the filtered drainage water 106 may then be pumped into the first ion exchange column 102.

[0035] The first ion exchange column 102 contains a first resin 112, which has an affinity for sulfate ions and nitrate ions that is greater than the first resin's affinity for chloride ions. The first ion exchange column 102 is configured to pass the predetermined mass flow rate of drainage water 106 therethrough. The drainage water 106 may have chloride ions and at least one of sulfate ions and nitrate ions contained therein. However, as is often the case, the drainage water 106 may contain substantial amounts of all three chloride ions, sulfate ions and nitrate ions.

[0036] The second ion exchange column 104 is connected in series fluid communication with the first ion exchange column 102. The second ion exchange column 104 contains a second resin 114, which at least has an affinity for chloride ions. However, the second resin 114 may also have an affinity for sulfate ions and nitrate ions that is greater than the second resin's affinity for chloride ions. Moreover, the second resin may be substantially the same as the first resin. The second ion exchange column 104 is also configured to pass the same predetermined mass flow rate of the same drainage water 106 therethrough.

[0037] As the drainage water 106 passes through the first ion exchange column 102, primarily the at least one of the sulfate ions and nitrate ions are removed from the drainage water 106 and exchanged for first ions in the first resin 114. In other words, if the drainage water 106 includes primarily sulfate ions and chloride ions, then the first ion exchange column 102 may remove primarily the sulfate ions. Additionally, if the drainage water 106 includes primarily nitrate ions and chloride ions, then the first ion exchange column may remove primarily the nitrate ions. However, if both sulfate ions and nitrate ions are present in the drainage water 106, then the first ion exchange column 102 may remove primarily both the sulfate ions and the nitrate ions and exchange them for the first ions in the first resin 112.

[0038] The first ions in the first resin 112 may be, for example, bicarbonate ions. The bicarbonate ions may exchange substantially one bicarbonate ion for a sulfate ion or a nitrate ion. For example, there are 500 milligrams per liter (mg/L) of target ions (e.g., both sulfate ions and nitrate ions) in the drainage water 106, then the first resin may release approximately 500 mg/L of bicarbonate ions into the drainage water 106 as it passes through the first ion exchange column.

[0039] As the drainage water 106 passes through the second ion exchange column 104, primarily the chloride ions are removed from the drainage water 106 and exchanged for second ions in the second resin 114. Again, the second ions in the second resin 114 may be, for example, bicarbonate ions, which may exchange substantially one bicarbonate ion for a chloride ion.

[0040] The drainage water 106 may then be returned to the irrigation system 116 for reuse. Advantageously, the drainage water 106 is returned to the irrigation system 116 almost completely free of the dissolved sulfate, nitrate and chloride ions.

[0041] In order to enhance the exchange of primarily sulfate ions and/or nitrate ions with the first ions and to enhance the exchange of primarily chloride ions with the second ions, the fluid velocity of the drainage water 106 in the first ion exchange column 102 may be configured to be greater than the fluid velocity of the drainage water 106 in the second ion exchange column. In other words, the first ion exchange column 102 may have a first geometry that induces a first fluid velocity of the drainage water 106 through the first ion exchange column 102. Additionally, the second ion exchange column 104 may have a second geometry that induces a second fluid velocity of the drainage water 106 through the second ion exchange column 104, wherein, the second fluid velocity is less than the first fluid velocity.

[0042] This may be the case even though the predetermined mass flow of drainage water 106 is substantially equal in both the first and second ion exchange columns 102, 104. For example, the first and second ion exchange columns each may have a substantially cylindrical geometry. The circular cross-sectional area of the first ion exchange column 102 may be about half the circular cross-sectional area of the second ion exchange column 104. In that case, much like a river which flows as fast moving rapids through a narrow gorge and later flows as slow moving calm water when the river becomes wider, the first fluid velocity of drainage water 106 through the relatively narrow first ion exchange column 102 will be about twice the second fluid velocity of the drainage water 106 in the wider second ion exchange column 104. By way of example, the second fluid velocity in the second ion exchange column 104 may be about one third to two thirds the first fluid velocity in the first ion exchange column 102, in order to maximize the ion exchange for the target ions in both ion exchange columns 102, 104.

[0043] Advantageously, the ion exchange system 100 separates the valuable nutrients (sulfate and nitrate ions) from the chloride ions. More specifically, because the chloride ions are segregated from the sulfate and/or nitrate ions, the sulfate and/or nitrate ions can be easily processed into a fertilizer for reuse, while the chloride ions can be treated to sequester the chloride.

[0044] Referring to FIG. 2, an example is depicted of a schematic view of the ion exchange system 100 of FIG. 1, wherein acid is injected into the drainage water 106 that is discharged from the second ion exchange column 104 to convert bicarbonate (HCO.sub.3) into carbon dioxide (CO.sub.2) prior to being reintroduced back into the irrigation system 116.

[0045] As the drainage water 106 passes through the first and second ion exchange columns 102, 104, it will pick up a substantial amount of bicarbonate ions (HCO.sub.3) in exchange for releasing its chloride, sulfate and/or nitrate ions. However, the ion exchange system 100 may be configured to include a bicarbonate removal tank 118. The bicarbonate removal tank 118 may be configured to receive the drainage water 106 that is discharged from the second ion exchange column 104. Thereafter, an acid injection system 120, may be configured to inject acid into the bicarbonate removal tank 118. The acid will convert bicarbonate ions (HCO.sub.3) contained in the drainage water 106 into carbon dioxide (CO.sub.2), which may be used for other purposes. The drainage water 106 will be substantially free of bicarbonate ions and may then be reintroduced into the irrigation system 116. Advantageously, the drainage water 106 is returned to the irrigation system 116 almost completely free of the dissolved sulfate and/or nitrate, chloride, and bicarbonate ions.

[0046] Referring to FIG. 3, an example is depicted of a schematic view of a regeneration system 130 associated with the ion exchange system 100 of FIG. 1, according to aspects described herein. After the drainage water has passed through the first and second ion exchange columns 102, 104, a regeneration system 130 may be used to regenerate the first ions in the first resin 112 and the second ions in the second resin 114 with bicarbonate ions. This regeneration process may occur during off hours or once the first and second resins 112, 114 have become fully exchanged with the chloride, sulfate, and/or nitrate ions.

[0047] The regeneration system 130 may include a first tank configured to contain a regenerate solution of ammonium bicarbonate. The regenerate solution may be in the form of a 10% ammonium bicarbonate solution. The first tank 132 is in selective fluid communication with a first three-way valve 134.

[0048] A second tank 136 of the regeneration system 130 is configured to contain fresh water. The second tank 136 is also in selective fluid communication with the first three-way valve 134. A first pump 138 has an intake port 140 in fluid communication with the first three-way valve 134.

[0049] A second three-way valve 142 is in fluid communication with an output port 144 of the first pump 138. The second three-way valve 142 is also in selective fluid communication with the first ion exchange column 102 and second ion exchange column 104. The first pump 138 is configured to pump the ammonium bicarbonate solution of the first tank 132 and the fresh water solution of the second tank 136 in the reverse flow direction, relative to the flow of drainage water 106, through either the first ion exchange column 102 or the second ion exchange column 104.

[0050] A first total dissolved solid (TDS) meter 146 monitors the percentage of total dissolved solids in discharge fluid (i.e., nutrient brine) 148 from the first ion exchange column 102. The nutrient brine 148 from the first ion exchange column flows into, and is collected in, a nutrient brine tank 150. A second TDS meter 152 monitors the percentage of TDS in discharge fluid (i.e., chloride brine) 154 from the second ion exchange column 104. The chloride brine 154 from the second ion exchange column 104 flows into, and is collected in, a chloride brine tank 156. The first and second TDS meters 146, 152 are in electronic communication with a control system 158, which is operable to control the operation of the first pump 138 and selection of the first and second three-way valves 134, 142. The first and second three-way valves 134, 142 are operable, via control system 158, to selectively provide fluid communication between: [0051] the first tank 132 and the first ion exchange column 102, [0052] the first tank 132 and the second ion exchange column 104, [0053] the second tank 136 and the first ion exchange column 102, and [0054] the second tank 136 and the second ion exchange column 104.

[0055] During operation, the regeneration system 130 is operable to pump, via the first pump 134, the regenerate solution (i.e., the ammonium bicarbonate solution) at a first flow rate from the first tank 132 through the first ion exchange column 102 in a reverse flow direction relative to the flow of drainage water 106. The resulting nutrient brine 148 from the first ion exchange column 102 is collected in the nutrient brine tank 150. The first TDS meter 146 monitors the amount of total dissolved solids (including the sulfate and/or nitrate ions) in real time and stops the process when the amount of TDS in the nutrient brine 148 has fallen to a value that is close to the TDS of the fresh water.

[0056] Thereafter, fresh water is pumped, via the first pump 138, at a second flow rate from the second tank 136 through the first ion exchange column 102 in the reverse flow direction. The fresh water is used to flush any additional contaminants out of the first ion exchange column 102. A resulting first water effluent from the first ion exchange column 102 is then collected in the nutrient brine tank 150. This is a fast rinse process, wherein the second flow rate of fresh water is faster than the first flow rate of regenerate solution.

[0057] At this point, the first ion exchange column 102 has been fully regenerated to a bicarbonate form. The nutrient brine tank 150 now contains ammonium salts of sulfate and/or nitrate and ammonium bicarbonate. This mixture can then be reused as a fertilizer. Bicarbonate (HCO.sub.3) contained in the nutrient brine tank 150 can be removed by acid injection as discussed earlier with respect to FIG. 2.

[0058] The second ion exchange column 104 may also be regenerated using substantially the same process. More specifically, during operation of the regeneration system 130, the regenerate solution may be pumped, via the first pump 138 at a third flow rate from the first tank 132 through the second ion exchange column 104 in the reverse flow direction. The resulting chloride brine 154 from the second ion exchange column 104 is collected in the chloride brine tank 156. The second TDS meter 152 monitors the amount of total dissolved solids (including the chloride ions) in real time and stops the process when the amount of TDS in the chloride brine 154 has fallen to a value that is close to the TDS of the fresh water.

[0059] Thereafter, fresh water is pumped, via the first pump 138, at a fourth flow rate from the second tank 136 through the second ion exchange column 104 in the reverse flow direction. The fresh water is used to flush any additional contaminants out of the second ion exchange column 104. A resulting first water effluent from the second ion exchange column 104 is then collected in the chloride brine tank 156. This is a fast rinse process, wherein the fourth flow rate of fresh water is faster than the third flow rate of regenerate solution. At this point the second ion exchange column has been fully regenerated back to a bicarbonate form.

[0060] Referring to FIG. 4, an example is depicted of a schematic view of a chloride brine processing system 160 associated with the regeneration system 130 of FIG. 3, according to aspects described herein. The chloride brine 154 collected in the chloride brine tank 156 during the regeneration process is a combination of ammonium salts, which requires further processing via a chloride brine processing system, such as the chloride brine processing system 160 of FIG. 4, prior to being reintroduced back into the irrigation system 116.

[0061] The chloride brine processing system 160 includes a second pump 162 configured to pump the chloride brine 154 from the chloride brine tank 156 to a first holding tank 164. A lime injection system 166 is configured to inject lime into the first holding tank 164 to raise the pH of the chloride brine 154 to about 12 and to convert the ammonium (NH.sub.4) in the chloride brine 154 to ammonia (NH.sub.3) gas. An ammonia collection tank 168 is configured to collect the ammonia gas. A third pump 170 is configured to pump the ammonia gas into the first tank 132 of the regeneration system 130. Advantageously, the ammonia gas is not wasted, but rather is incorporated into the regenerate solution of ammonium bicarbonate in the first tank 132.

[0062] The chloride brine processing system 160 may also include a sodium aluminate injection system 172, which is configured to inject sodium aluminate into the first holding tank 164 to form a calcium-aluminum-chloride based Friedel's salt. An anionic polyacrylamide (PAM) injection system 174 may be configured to inject PAM into the first holding tank 164 to result in a suspension of solids and supernatant.

[0063] A fourth pump 176 may be configured to pump the suspension into an at least one settling tank 178. The at least one settling tank 178 may be a single first settling tank 178A or may include additional settling tanks, such as second settling tank 178B. In the example illustrated in FIG. 4, two settling tanks 178A and 178B are shown. An acid injection system 180 may be configured to inject acid into the first settling tank 178A to reduce the pH of the suspension to about 7 and to convert bicarbonate ions (HCO.sub.3) into carbon dioxide (CO.sub.2).

[0064] The first settling tank 178A may be configured to enable the solids of the suspension to be drained off of the bottom of the first settling tank 178A. Alternatively, the suspension may be moved to the second settling tank 178B of the at least one settling tanks 178, wherein the solids may be separated by draining the solids from the bottom of the second settling tank 178B and deposited in a solid collection tank 182.

[0065] At this point, the resulting supernatant in the second settling tank 178B is advantageously free of substantially all chloride ions. Therefore, the resulting supernatant may be pumped, via a fifth pump 184 back into the irrigation system 116.

[0066] Referring to FIG. 5, an example is depicted of a schematic view of another brine processing system 190 associated with the regeneration system 130 of FIG. 3, according to aspects described herein. The chloride brine processing system 190 may include a mixing tank 192 containing calcinated hydrotalcite. The calcinated hydrotalcite is operable to absorb the chloride from the chloride brine 154 of the chloride brine tank 156. The chloride brine 154 may be pumped from the chloride brine tank 156 via a sixth pump 194. The calcinated hydrotalcite may then be landfilled once it reaches its maximum capacity for chloride.

[0067] Referring to FIG. 6, an example is depicted of a schematic view of another brine processing system 200 associated with the regeneration system of FIG. 3, according to aspects described herein. The chloride brine processing system 200 may include an acid injection system 202. The acid injection system may be configured to inject an acid into the chloride brine 154 of the chloride brine tank 156 to convert bicarbonate (HCO.sub.3) of the chloride brine 154 into carbon dioxide (CO.sub.2) and leaving an ammonium based liquid fertilizer. The fertilizer may be pumped back into the irrigation system 116.

[0068] Referring to FIG. 7, a flow diagram is depicted of a method 300 of removing chloride ions, sulfate ions and/or nitrate ions from drainage water 106, using a first ion exchange column 102 in series fluid communication with a second ion exchange column 104 as exemplified in FIG. 1, according to aspects described herein. Drainage water 106 may come from irrigation water that is used to irrigate crops in an agricultural system and then drained through an agricultural drainage system. Such drainage water often contains chloride ions, sulfate ions and/or nitrate ions that should be separated from the drainage water before being returned to the local ecosystem. The sulfate ions and/or nitrate ions can easily be processed into a fertilizer that provides nutrients for crops on an irrigation system 116. However, chloride ions require additional processing before either being returned to an irrigation system or landfilled. When chloride ions are mixed in with sulfate ions and/or nitrate ions, it has often been difficult to separate them using prior art regeneration systems and often the entire effluent must be landfilled. The following method 300 advantageously provides a cost efficient, low power way of separating the chloride ions from the sulfate ions and/or nitrate ions.

[0069] The method begins at 302 wherein drainage water 106 having chloride ions and at least one of sulfate ions and nitrate ions is passed through a first ion exchange column 102 at a predetermined mass flow rate. The first ion exchange column 102 containing a first resin 112 having an affinity for sulfate ions and nitrate ions that is greater than the first resin's affinity for chloride ions.

[0070] At 304, bicarbonate ions in the first resin are exchanged with primarily the at least one of sulfate ions and nitrate ions in the drainage water 106.

[0071] At 306, the drainage water 106 is passed through a second ion exchange column 104 at the same predetermined mass flow rate. The second ion exchange column contains a second resin 114 having an affinity for chloride ions.

[0072] At 308, bicarbonate ions in the second resin 114 are exchanged with primarily the chloride ions in the drainage water 106. Advantageously, the nutrient ions (i.e., nitrate and/or sulfate) are now separated from the chloride ions.

[0073] To optimize the exchange of resins, the drainage water 106 passing through the first ion exchange column 102 may do so at a first fluid velocity, and the same drainage water passing through the second ion exchange column 104 may do so at a second fluid velocity, even though the mass flow rate of the fluid is substantially constant in both the first and second ion exchange columns. The second fluid velocity may be less than the first fluid velocity. More specifically, the second fluid velocity may be about one third to two thirds the first fluid velocity for optimal performance. Moreover, the first resin and the second resins may be substantially the same resin.

[0074] Additionally, the method may include pumping the drainage water 106 from the second ion exchange column 102 into a bicarbonate removal tank 118 as exemplified in FIG. 2. Thereafter, acid is injected into the bicarbonate removal tank 118 to convert bicarbonate ions (HCO.sub.3) contained in the drainage water 106 into carbon dioxide (CO.sub.2), prior to pumping the drainage water into an irrigation system 116.

[0075] Referring to FIG. 8, a flow diagram is depicted of a method 310 of regenerating the first and second ion columns 102, 104 of FIG. 7. The nutrient brine 148 (containing sulfate ions and/or nitrate ions) from the first ion exchange column 102 is pumped into a nutrient tank 150 and chloride brine 154 from the second ion exchange column 104 is pumped into a chloride brine tank 156 (as illustrated in FIG. 3), according to aspects described herein.

[0076] The method begins at 312, wherein a regenerate solution of ammonium bicarbonate is pumped at a first flow rate through the first ion exchange column 102 in a reverse flow direction relative to the flow of drainage water. The resulting nutrient brine 148 is collected from the first ion exchange column 102 in the nutrient brine tank 150.

[0077] At 314 of the method 300, fresh water is pumped at a second flow rate through the first ion exchange column 102 in the reverse flow direction. The resulting first water effluent from the first ion exchange column 102 is collected in the nutrient brine tank 150. The second flow rate may be faster than the first flow rate.

[0078] At 316, the regenerate solution is pumped at a third flow rate through the second ion exchange column 104 in the reverse flow direction. The resulting chloride brine 154 from the second ion exchange column 104 is collected in the chloride brine tank 156.

[0079] At 318, fresh water is pumped at a fourth flow rate through the second ion exchange column 104 in the reverse flow direction. The resulting second water effluent from the second ion exchange column 104 is collected in the chloride brine tank 156. The fourth flow rate is faster than the third flow rate.

[0080] Referring to FIG. 9, a flow diagram of a method 320 of processing chloride brine 154 of the chloride brine tank of FIG. 8 is depicted, according to aspects described herein. The chloride brine 154 collected in the chloride brine tank 156 during the regeneration process is a combination of ammonium salts, which requires further processing via a chloride brine method, such as the chloride brine processing method 320 of FIG. 9, prior to being reintroduced back into the irrigation system 116.

[0081] The method begins at 322, wherein lime is injected into the chloride brine tank 156 to raise the pH of the chloride brine 154 to about 12 and to convert the ammonium (NH.sub.4) in the chloride brine 154 to ammonia (NH.sub.3) gas.

[0082] At 324, the ammonia gas is collected.

[0083] At 326, the collected ammonia gas is advantageously pumped back into the regenerate solution of ammonium bicarbonate in the ammonium bicarbonate tank 132 for further use.

[0084] At 328 of the method 320, sodium aluminate is injected into the chloride brine tank 156 to form a calcium-aluminum-chloride based Friedel's salt.

[0085] At 330, an anionic polyacrylamide (PAM) is injected into the chloride brine tank 156 to form a suspension of solids and supernatant.

[0086] At 332, the suspension is pumped into an at least one settling tank 178. There may be more than one settling tank, such as a first settling tank 178A and a second settling tank 178B, as illustrated in FIG. 4.

[0087] At 334, acid is injected into the at least one settling tank 178 to reduce the pH of the suspension to about 7 and to convert bicarbonate ions (HCO.sub.3) into carbon dioxide (CO.sub.2).

[0088] At 336, the solids of the suspension are drained off of the bottom of the at least one settling tank 178.

[0089] Referring to FIG. 10, a flow diagram is depicted of another method 340 of processing the chloride brine 154 in the chloride brine tank 156 of FIG. 8, according to aspects described herein.

[0090] The method begins at 342, wherein the chloride brine 154 of the chloride brine tank 156 is mixed with calcinated hydrotalcite. The calcinated hydrotalcite is operable to absorb the chloride from the chloride brine 154 of the chloride brine tank 156. Once the calcinated hydrotalcite reaches its maximum capacity for absorbing the chloride brine 154, the calcinate hydrotalcite is landfilled.

[0091] Referring to FIG. 11, a flow diagram of another method 350 of processing the chloride brine 154 of the chloride brine tank of FIG. 8 is depicted, according to aspects described herein.

[0092] The method begins at 352, wherein an acid is injected into the chloride brine 154 of the chloride brine tank 156. The acid converts the bicarbonate (HCO.sub.3) of the chloride brine 154 into carbon dioxide (CO.sub.2), leaving an ammonium based liquid fertilizer. The liquid fertilizer may be introduced into an irrigation system 116.

[0093] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail herein (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.

[0094] Although the invention has been described by reference to specific examples, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the disclosure not be limited to the described examples, but that it have the full scope defined by the language of the following claims.