Novel regeneration of mixed-bed ion exchange resins for seawater desalination

Abstract

The present invention is directed to a novel ion exchange regeneration process that does not require resin separation or the consumption of acid and base for regeneration. Exhausted strong acid / strong base mixed-bed resins suitable for seawater desalination can be regenerated in situ, i.e., without the need for bead separation, by washing with concentrated ammonium bicarbonate (AB) solution (up to 8-10 m concentration) at moderately elevated temperatures (up to 600-800°C) under high pressure (<10 atm). Under these conditions, a relatively small amount of AB solution can be used to regenerate the exhausted mixed-bed resin and convert it to a form saturated with absorbed NH4+ and HCO3- ions. This resin can then be used for seawater desalination via direct exchange with Na+ and Cl- ions and other ions in seawater. The volume of potable water produced by this method can be at least two to four times the volume of AB solution required, which is subsequently discarded as a waste concentrated salt solution. AB dissolved in desalinated product water can be easily thermally decomposed by heating to below 600-800°C under reduced pressure, completely removing the AB in the form of evolved gases NH3 and CO2, which can then be captured and redissolved in cold water to reform the regenerant solution. The application of increased pressure to drive supersaturated ammonium bicarbonate regeneration can also be accomplished using guided ultrasound. Guided ultrasound of appropriate frequency and intensity transmitted along the inside of a vessel containing spent mixed-bed resin immersed in a concentrated or supersaturated AB solution drives the ion exchange regeneration process. Alternatively, pressure applied to the resin can be generated via centrifugal force generated inside a rotating drum.

Description

[Technical Field]

[0001] The present invention relates to an improved method for regenerating exhausted mixed bed ion exchange resins, particularly for use in seawater and brackish water desalination. The process disclosed in this invention reduces significant levels of Mg in seawater. 2+ In addition, the process disclosed in this invention can be used to recover radioactive strontium (Sr 2+ ) and many other valuable multivalent ions such as rare earth metals. [Background technology]

[0002] Technology Background Current desalination techniques, such as distillation and reverse osmosis (RO), are highly energy intensive and often not economically viable. Seawater RO (SWRO) requires sophisticated control systems and expensive, specialized membranes. It also requires pretreatment of the seawater to protect the membrane from fouling, and even then, the membranes must be periodically discarded and replaced. Seawater must typically be pressurized to up to 70 atm, and sophisticated pressure recycle systems are used to reduce costs. Thermal methods are tightly controlled by the heat energy demands of the high enthalpy of water vaporization; even with energy recovery systems, these units can only be feasible with the availability of industrial waste heat, such as when built adjacent to power plants and other industrial plants.

[0003] The ancient Greeks knew how to produce "fresh" water from seawater via a simpler ion exchange process by running the seawater through clay soil. The ion exchange process was modernized with the development of the first plastic or polymer-based synthetic resins. This technology offers several advantages in desalination. Some of these are attributable to traditional resin ion exchange techniques, such as low input pressure, simple setup, and high efficiency, which do not require extensive feedwater pretreatment.

[0004] Mixed bed ion exchange processes are often used to produce "distilled water" from slightly saline or even brackish water, but are rarely used to produce drinking water from seawater.

[0005] This is because strong anion and strong cation exchange resin beads must be regenerated upon exhaustion, requiring their physical separation and washing with strong acid and base solutions, which not only damages the resin polymer but also results in complete wastage and is prohibitively expensive.

[0006] Prior art Recently, it has been disclosed that ammonium bicarbonate (AB) solution can be used to regenerate these mixed-bed resins in situ without the need to separate the cation and anion resins, resulting in a simpler, more efficient process and extending the life of the resins due to the lack of exposure of these resins to the strong acids and bases used in traditional regeneration methods. Such a method is disclosed in WO 2020 / 118371. The primary improvement comes from completely eliminating the need to consume large amounts of expensive acids and bases. Summary of the Invention [Problem to be solved by the invention]

[0007] Problems with the prior art An efficient commercial process must produce a significantly larger volume of demineralized water than is required for the AB solution needed to regenerate the exhausted mixed bed resin. To date, this problem has not been solved.

[0008] Desalination of seawater usually involves the use of Na + and C1 - ions, plus significant levels of dissolved Mg 2+ and SO4 2- With the removal of ions, divalent ions are more preferentially absorbed onto the resin, making regeneration more difficult. The present invention aims to solve the problems faced by the AB regeneration method, especially when applied to the production of drinking water from seawater.

[0009] The main ionic component in seawater is Cl. - :0.55M, Na + :0.47M, Mg 2+ :0.053M, SO4 2- :0.028M.

[0010] All of these ions can be electrostatically bound to oppositely charged groups on ion exchange resins, and they can all be removed by exposure to higher concentrations of the same type of ion, i.e., cations in the case of cations and anions in the case of anions. However, divalent ions must be replaced using higher concentrations of monovalent ions of the same charge.

[0011] To regenerate a mixed bed resin depleted by seawater, it is important to use a significantly higher concentration of a solute such as AB, which is possible due to the high water solubility of AB. Increasing the temperature is one way to increase the concentration of the AB solution. However, increasing the temperature can cause AB to decompose into ammonia and carbon dioxide gas. The present invention aims to address this problem. [Means for solving the problem]

[0012] Summary of the Invention Ammonium bicarbonate is highly soluble in water, especially as the temperature increases. However, increasing the temperature also causes the salt to decompose into ammonia and carbon dioxide gas. To address this issue, the present invention discloses an efficient AB regeneration process driven by the use of increased pressure and temperature to generate a supersaturated AB solution. The pressure required for the AB regeneration process can be provided by direct pressure application or through the use of heating, ultrasound, or even centrifugal force.

[0013] When excess salt is added to the ammonium bicarbonate solution, it decomposes as the temperature is raised to a maximum of about 60°C in a sealed vessel, which can be used to create an increase in the partial pressure of both NH3 and CO2 which acts to drive AB regeneration of the mixed bed resin.

[0014] For example, AB begins to decompose in aqueous solutions above about 40° C., but its solubility also increases as shown below. At 40°C, the AB solubility is 36.6 g / 100 g of water, which corresponds to 4.6 m At 60°C, the AB solubility is 60g / 100g of water, which corresponds to 7.6m.

[0015] According to the novel process of the present invention, at these higher temperatures the partial pressure is increased to prevent AB decomposition.

[0016] The pressure required to maintain a specific solubility can be estimated from Henry's law for gas solubility in solution. Thus, for AB solubility at 4 atm pressure, the solubility increases to approximately 8 M, reducing the volume of regenerant solution required. Under these conditions of higher concentration and elevated temperature, the production ratio of demineralized water produced to AB regenerant solution volume for resin regeneration increases and may exceed commercial process demand. This results in the production of excess demineralized water during the process. When a supersaturated AB solution is heated in a pressure vessel, the decomposition of AB increases the partial pressures of both ammonia and carbon dioxide, driving the regeneration process.

[0017] This finding of the present invention is also strongly supported by a very important consideration based on a fundamental thermodynamic law called Le Chatelier's principle. When applied to pressurized regenerant processes, this universal principle states that the increased pressure (partial pressure) of NH3 and CO2 gases increases the rate of NH4 deposition on the resin. + and HCO3 -This means driving the absorption of ions and therefore removing them from solution, since they are always in dynamic equilibrium with ammonia and carbon dioxide gases, and therefore pressure must be applied to prevent AB decomposition.

[0018] Le Châtelier's principle predicts that the system can only do this by responding to the applied pressure in an opposing manner, forcing more of these ions into the resin. + , Cl - and Mg 2+ and SO4 2- Ions have no pressure change associated with whether they are in solution or on a resin, and therefore are not driven differently by the application of pressure.

[0019] In addition, NH4 + and HCO3 - It should also be appreciated that because the ions are adsorbed onto separate beads, i.e., anion and cation ion exchange beads, within the mixed bed, the different adsorbed ions are physically separated by only about 1 mm and therefore cannot decompose, since decomposition into two gases requires that a water molecule be extracted from the NH4HCO3 molecule.

[0020] This makes AB regeneration with pressure ideal for mixed bed resins: once the AB is absorbed into the resin, reducing this pressure does not make much difference and can drain off concentrated NaCl, especially if the temperature is allowed to return to room temperature before the pressure is released.

[0021] Any strong acid-base mixed bed resin can be used as the resin in the process disclosed in this invention. One suitable resin for practicing this invention is LEWATIT® MonoPlus SM 1000 KR resin, which is a ready-to-use mixed bed containing a fully regenerated form of a strongly acidic gel-type cation exchange resin and a strongly basic gel-type anion exchange resin. In this mixed resin, the anion ion exchange capacity is half that of the cation, so they are mixed in a 2:1 ratio. The functional groups of the anion ion exchanger contain quaternary ammonium (quat) groups, and the cation ion exchanger contains sulfonic acid groups.

[0022] This novel process is equivalent to the separation of products produced in a chemical reaction, which is often used to drive the reaction forward and prevent the reverse reaction. While the present invention focuses more on the most difficult problem of seawater desalination, it should be noted that this process also significantly further improves the rate of brackish water production.

[0023] In addition, the novel AB regeneration process of the present invention reduces significant levels of Mg in seawater absorbed by the resin. 2+ It has been observed that the process disclosed in this invention produces magnesium carbonate / magnesium bicarbonate precipitate as a by-product derived from radioactive strontium (Sr 2+ ) and many other valuable multivalent ions such as rare earth metals.

[0024] In particular, the novel process of the present invention comprises the following main steps:

[0025] First stage: A continuous flow of ionic solution, such as seawater, is passed through the mixed bed, strong acid and strong base resins, and the ion exchange groups are preferably ionized with NH4 + and HCO3 - ions initially saturated with essentially desorbed NH4 + and HCO3 - Drinking water (volume Vp) containing only ions is produced.

[0026] Second stage: The product water is heated to 60-80°C or lower with reduced pressure to completely remove the AB solutes as CO2 and NH3 gases and produce the final product water (volume Vp).

[0027] Third stage: The evolved gas is first collected by decomposition in cold water and then further concentrated by decomposition under pressure (up to 10 atm) and heating of the solution to up to 80°C to produce up to 8 m of AB regenerant solution (volume Vr).

[0028] Stage 4: The heated regenerant solution is then pumped under pressure into the vessel (ion exchange column) holding the resin depleted by seawater. The vessel is sealed and NH4 + and HCO3 - The vessel is continuously rotated or shaken to allow mixing for a period of time until the pressure in the vessel drops to a lower equilibrium value, indicating that the ions have replaced the seawater ions absorbed by the resin. As the supersaturated AB solution is heated in the pressure vessel, decomposition of AB increases the partial pressures of both ammonia and carbon dioxide, driving the regeneration process.

[0029] Stage 5: The temperature and pressure within the resin vessel are then reduced to ambient conditions, and the salt concentrate (a volume of approximately Vr) is completely drained (or pushed out, for example, by a pressurized air stream) from the resin and discarded.

[0030] The process then repeats from step one.

[0031] Detailed Description of the Invention Notwithstanding any other aspects of the invention which may fall within the scope of the disclosed process and apparatus, specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings 1-3. [Brief explanation of the drawings]

[0032]

[0013] Figure 1 is a schematic diagram of a desalination process according to the present invention, including a regeneration step using a supersaturated ammonium bicarbonate solution under pressure. The reference numerals used in Figure 1 to describe various features of the apparatus used in the present invention are as follows: JPEG2025536886000002.jpg31105 [Figure 2] Schematic diagram showing the characteristics of a standard wave. [Figure 3] A schematic example of guided ultrasound in a pipe vessel used for ion exchange. In this diagram, item 1 is a pipe-shaped vessel used as an ion exchange unit that can be used either vertically or horizontally. Item 2 represents the ultrasonic transducer or emitter. Item 3 is a strong acid-base mixed bed resin. This pipe vessel can be used either horizontally or vertically, as shown in Figure 3. DETAILED DESCRIPTION OF THE INVENTION

[0033] The configuration of an apparatus for desalination of seawater using the present invention will be described below with reference to FIG.

[0034] In Figure 1, item 101 is an ion exchange vessel, i.e., a column packed with a strong acid-base mixed bed resin. During the operating cycle, the resin is in the form of ammonium bicarbonate (AB). During the operating cycle, valves V3 and V4 are in the closed position. Valves V1 and V2 are in the open position.

[0035] In operation, seawater is pumped through valve V1 into ion exchange column 101. As the seawater passes through the column, the Na + and Cl - The ions are exchanged with the ammonium and bicarbonate ions in the resin.

[0036] The product water containing AB exits ion exchange column 101 via valve V2 and enters vessel 102, which is used to decompose the AB solution. Decomposition of AB is carried out by heating vessel 102 to an appropriate temperature (approximately 60° C.).

[0037] Clean water produced by the decomposition of AB exits the vessel. CO2 and NH3 gases generated during the decomposition process are directed to vessel 103 where they are combined with a portion of the clean water generated by the decomposition process.

[0038] In vessel 103, CO, NH, and water are subjected to higher temperature (60° C.) and pressure (above 1 atm) to produce a supersaturated AB solution, which is pumped under pressure through valve V3 (while V1 and V2 are in the closed position) into ion exchange vessel or column 101.

[0039] The supersaturated AB solution passes under pressure through the resin in the ion exchange column, transferring ammonium and bicarbonate ions to the Na ions attached to the resin. + and CO - The concentrated waste salt solution is discharged via valve V4.

[0040] All Na + and Cl - After the ions are removed, the cycle is again changed to an operating cycle by pumping the seawater through the ion exchange column 101 again.

[0041] The production ratio (Vp / Vr) can be targeted in the range of 2 to 4 for normal seawater supply.

[0042] Another preferred embodiment of the present invention is that the AB regeneration process can be driven by increasing positive pressure acting in only one direction, so that the reverse ion exchange reaction cannot occur even if the pressure is reduced or reversed. This is because the anion and cation exchange beads are physically separated, thereby preventing thermal or low-pressure decomposition of AB, which can only occur via complex salts. This embodiment is based on the use of NH4 + and HCO3 - Na on exhausted mixed bed resin by ions + and Cl -This is based on the observation that pressure-driven displacement of ions can only work in one direction, since AB can only dissociate in the complex salt state. Individual ions cannot dissociate even under negative pressure because they are physically separated on two different ion-exchange beads, i.e., anion and cation exchange beads.

[0043] This embodiment of the present invention uses guided ultrasound of appropriate frequency and intensity transmitted along the inside of a vessel containing spent mixed-bed resin immersed in a concentrated or supersaturated AB solution to apply pressure in one direction. This embodiment can be used to significantly reduce the need to increase both background temperature and pressure during the regeneration process, resulting in significant energy savings and reducing the required operating time. At the end of the process, the AB can be easily recycled through low-temperature pyrolysis by heating to 60-80°C to reform the regenerant solution, which completely removes the AB in the form of evolved gases NH3 and CO2, which can then be captured and redissolved in cold water.

[0044] Ultrasound can be used to efficiently provide a suitable transient pressure source to generate a pressure increase that affects the exchange reaction in only one direction. This pressure increase across the exhausted resin during immersion in a concentrated or supersaturated AB solution can assist or even drive regeneration in a low-energy process. Ultrasound is a pressure wave with a frequency above the human hearing range of 20 kHz. The speed at which these waves travel depends on the medium; in seawater, this is approximately 1500 m / s. Human imaging ultrasound scanners operate at higher frequencies, approximately 10 MHz. Figure 2 shows the waveform of such a wave.

[0045] The velocity of ultrasound is obtained by multiplying the frequency by the wavelength. Thus, at 40 kHz the wavelength is 1500 / 20000 = 0.075 m or 7.5 cm, and at 10 MHz (such as in a body scanner) the wavelength is 1500 / 107 = 0.00015 m or 0.15 mm. This indicates that a wide range of frequencies and wavelengths are available for transient increases in local pressure, which can be used to drive the AB ion exchange process.

[0046] Ultrasound has been used to test fluid-filled piping using either point-by-point defect detection with bulk ultrasound or long-distance inspection with guided waves. Guided wave ultrasonic testing (GWUT) is more suited to damage detection within large areas. Guided waves propagate long distances along the structure being inspected, allowing the entire structure to be surveyed in a short time. Depending on the required application, there are many different geometries that can be used to create a waveguide configuration. Such guided waves can be used in the process described in this invention.

[0047] Ultrasonic transducers convert alternating current (AC) into ultrasonic waves, and vice versa. Transducers typically use piezoelectric or capacitive transducers to generate or receive ultrasonic waves. Piezoelectric crystals can oscillate over a wide frequency range in response to an applied voltage signal. This oscillation can generate ultra-high frequency sound waves. Piezoelectric transducers can be mounted on the exterior wall of the container or in direct contact with the fluid inside the container, as desired.

[0048] FIG. 3 is a schematic representation of a guided ultrasonic waveguide configuration for use with a pipe vessel, according to one embodiment of the present invention.

[0049] As shown in Figure 3, non-axisymmetric partial loading by a small single-element transducer excites multiple modes (both longitudinal and flexural guided waves) within the pipe. The excited flexural modes have displacement fields in all three directions (radial, circumferential, and axial). When the excitation source input is over a wide range of frequencies, many more flexural guided wave modes are produced, whose diverse wavelengths are beneficial for generating a wide range of forced pressure-driven interactions suitable for supporting this pressure-driven ion exchange process throughout the trapped fluid and resin mixture.

[0050] The process of the present invention has been described above in relation to the desalination of seawater or brackish water. 2+ and for the purification of any other contaminated wastewater to remove multivalent ions such as ions of rare earth metals.

[0051] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to those skilled in the art that various modifications in form and detail may be made to adapt to different situations without departing from the spirit and scope of the invention. Accordingly, the present invention is not limited by any of the illustrative embodiments described above.

Claims

1. 1. A process for desalination of seawater or brackish water, comprising: a. Passing a continuous stream of seawater or brackish water through a mixed-bed ion exchange column containing strong acid and strong base resins, wherein the ion exchange groups are initially NH 4 + and HCO 3 - The resin is saturated with ions and essentially desorbed NH 4 + and HCO 3 - producing demineralized water containing ions; b. Desorbed NH produced in the preceding step 4 + and HCO 3 - The demineralized water containing ions is heated to a temperature of 60-80°C or lower with reduced pressure to convert the ammonium bicarbonate solute to CO 2 and N.H. 3 completely removing the gas to produce a desalinated product water; c. The released gas CO 2 and N.H. 3 with a portion of the generated desalinated product water to form an ammonium bicarbonate solution; d. concentrating the ammonium bicarbonate solution by subjecting it to higher pressure and temperature to produce a supersaturated ammonium bicarbonate regenerant solution; e. The ammonium and bicarbonate ions in the regenerant solution are converted to sodium and chloride (as well as Mg) in the spent resin while being heated to decompose the supersaturated ammonium bicarbonate regenerant and raise the partial pressure of both ammonia and carbon dioxide which drive the regeneration process. 2+ and SO 4 2- regenerating the spent resin in the ion exchanger column by passing the supersaturated ammonium bicarbonate regenerant solution through the column by exchanging it with ammonium bicarbonate ions; f. Discharging the concentrated sodium chloride solution from the ion exchange column; g. Repeating steps a to f. A process involving:

2. 10. The process of claim 1, wherein the volume of desalinated product water produced exceeds the volume of the ammonium bicarbonate regeneration solution used, resulting in a net surplus of desalinated product water.

3. 3. The process of claim 2, wherein the concentration of the ammonium bicarbonate solution is carried out at a pressure of 1 to 10 atm and a temperature of 40° C. to 80° C. to produce a regenerant solution having an ammonium bicarbonate concentration of up to 8 molar.

4. The heated regenerant solution is fed under pressure into the ion exchange column containing the spent resin, and the ion exchange column is heated to a temperature of 1000° C. for 1 hour. 4 + and HCO 3 - 4. The process of claim 3, wherein the vessel is continuously rotated or vibrated to allow mixing for a period of time until the pressure within the vessel drops to a lower equilibrium value, indicating that ions have replaced seawater ions absorbed by the resin.

5. 5. The process of claim 4, wherein the temperature and pressure in the ion exchange column are reduced to ambient conditions before discharging the concentrated sodium chloride solution.

6. 6. The process of claim 5, wherein the regeneration process is driven by an increase in positive pressure acting in only one direction.

7. 7. The process of claim 6, wherein guided ultrasound is used to transiently generate an increase in positive pressure to pressurize all areas of the seawater-depleted mixed bed ion exchange resin immersed in a concentrated or supersaturated solution of ammonium bicarbonate in the ion exchange column to drive a resin regeneration process via ion exchange.

8. 8. The process of claim 7, wherein the frequency of the guided ultrasound is in the range of 20 kHz to 20 MHz.

9. Magnesium in the form of magnesium carbonate or magnesium bicarbonate precipitates can be used to reduce the significant levels of Mg present in seawater absorbed by the resin. 2+ The process of any one of claims 1 to 8, wherein the hydroxybenzoate is recovered as a by-product from

10. 1. A process for treating wastewater containing dissolved electrolytes, comprising: a. Passing a continuous stream of said electrolyte wastewater through a mixed bed ion exchange column containing strong acid and strong base resins, wherein the ion exchange groups are initially NH 4 + and HCO 3 - The resin is saturated with ions and essentially desorbed NH 4 + and HCO 3 - forming an ammonium bicarbonate solution containing ions; b. Heating the ammonium bicarbonate solution produced in the preceding step to a temperature of 60-80°C or lower under reduced pressure to convert the ammonium bicarbonate solute into CO 2 and N.H. 3 completely removing the product as a gas to produce a treated product water; c. The released gas CO 2 and N.H. 3 with a portion of the treated product water to form an ammonium bicarbonate solution; d. concentrating the ammonium bicarbonate solution by subjecting it to higher pressure and temperature to produce a supersaturated ammonium bicarbonate regenerant solution; e) regenerating the exhausted resin in the ion exchanger column by passing the supersaturated ammonium bicarbonate regenerant solution through the column while being heated to decompose the supersaturated ammonium bicarbonate regenerant and increase the partial pressures of both ammonia and carbon dioxide which drive the regeneration process, thereby exchanging the ammonium and bicarbonate ions in the regenerant solution for the ions of the electrolyte in the exhausted resin; f. Discharging the concentrated waste solution from the ion exchange column; g. Repeating steps a to f. A process involving:

11. 11. The process of claim 10, wherein the volume of treated product water produced exceeds the volume of the ammonium bicarbonate regeneration solution used, resulting in a net surplus of treated product water.

12. 12. The process of claim 11, wherein the concentration of the ammonium bicarbonate solution is carried out at a pressure of 1 to 10 atm and a temperature of 40°C to 80°C to produce a regenerant solution having an ammonium bicarbonate concentration of up to 8 molar.

13. The heated regenerant solution is fed under pressure into the ion exchange column containing the spent resin, and the ion exchange column is heated to a temperature of 1000° C. for 1 hour. 4 + and HCO 3 - 13. The process of claim 12, wherein the vessel is continuously rotated or vibrated to allow mixing for a period of time until the pressure within the vessel drops to a lower equilibrium value, indicating that ions have replaced electrolyte ions absorbed in the resin.

14. 14. The process of claim 13, wherein the temperature and pressure in the ion exchange column are reduced to ambient conditions before discharging the concentrated spent electrolyte solution.

15. 15. The process of claim 14, wherein the regeneration process is driven by increasing positive pressure which forces the ion exchange reaction in only one direction.

16. 16. The process of claim 15, wherein induced ultrasound is used to generate an increase in positive pressure to transiently pressurize all areas of the exhausted mixed bed ion exchange resin that are immersed in a concentrated or supersaturated solution of ammonium bicarbonate in the ion exchange column to drive a resin regeneration process via ion exchange.

17. 17. The process of claim 16, wherein the frequency of the guided ultrasound is in the range of 20 kHz to 20 MHz.

18. Radioactive strontium (Sr 2+ 18. The process according to any one of claims 10 to 17, for removing rare earth metals.

19. 1. An apparatus for treating an ionic solution by ion exchange, comprising: A mixed bed ion exchange column containing strong acid and strong base resins, the ion exchange groups being initially NH 4 + and HCO 3 - The resin is saturated with ions and essentially desorbed NH 4 + and HCO 3 - a mixed bed ion exchange column for producing treated water containing ions; Desorbed NH 4 + and HCO 3 - The treated water containing ions is heated to 60-80°C or lower under reduced pressure to convert the ammonium bicarbonate solute into CO 2 and N.H. 3 means for completely removing the gas to produce product water; The released gas CO 2 and N.H. 3 with a portion of the produced product water to form an ammonium bicarbonate solution; means for concentrating the ammonium bicarbonate solution by subjecting it to higher pressures and temperatures to produce a supersaturated ammonium bicarbonate regenerant solution; means for regenerating the exhausted resin in the ion exchanger column by passing the supersaturated ammonium bicarbonate regenerant solution through the column to exchange ammonium and bicarbonate ions in the regenerant solution for ions in the exhausted resin while being heated to decompose the supersaturated ammonium bicarbonate regenerant and raise the partial pressures of both ammonia and carbon dioxide which drive the regeneration process; means for draining concentrated waste solution from said ion exchange column using either applied pressure or residual pressure from said regenerant process; An apparatus comprising:

20. 20. The apparatus of claim 19, further comprising means for applying a pressure transient to pressurize all regions of the mixed bed ion exchange resin immersed in the concentrated or supersaturated solution of ammonium bicarbonate in the ion exchange column to drive a resin regeneration process via ion exchange.

21. 21. The apparatus of claim 20, wherein the means for applying transient pressure is via guided ultrasound having a frequency range of 20 kHz to 20 MHz or by using a rotating drum to generate centrifugal pressure on the resin.

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