JPH09117677A - Regeneration of countercurrent ion exchange tower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a simple and compact ion exchange tower to be regenerated in a short time and operated stably. SOLUTION: An intermediate diaphragm 2 is installed near an intermediate part, and a strong ion exchange resin is packed in a lower chamber 5 and a weak ion exchange resin is packed in an upper chamber 8. Each of these chambers is filled with free boards 6, 9 and inactive resins with a specific gravity of 1.0 or less on the free boards. In the method for regenerating this countercurrent ion exchange tower, the following steps (a)-(e) are performed: (a) a step to discharge a suspended substance accumulated at the time of water flow by a back wash at a high speed flow velocity from a lower water, collecting device 4 and at the same time, form an ion exchange resin-fixed layer, (b) a step to maintain the fixed layer of (a) in a satisfactory operating state and flow a regenerating agent to the fixed layer from the lower water collecting device, (c) a step to maintain the fixed layer in a satisfactory operating state and extrude the regenerating agent by flowing a treated water from the lower water collecting device, (d) a step to introduce water from below, the intermediate diaphragm 2 at a low flow velocity and back wash only the upper chamber 8, and (e) a step to flow water from an upper water collecting device 3 for cleaning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an intermediate partition wall near the middle of a tower that allows water but not an ion exchange resin to pass through the tower, and an upper chamber filled with a weak ion exchange resin and a strong ion exchange resin. Downflow water divided into two filled lower chambers
The present invention relates to a method for regenerating a countercurrent ion exchange tower that performs upflowing medicine.

[0002]

2. Description of the Related Art In recent ion exchange apparatuses, a countercurrent type is often adopted because a regenerant can be saved and good treated water quality can be obtained. In the case of a deionizer, depending on the quality of the raw water, strong acid cation exchange resin (hereinafter referred to as strong cation resin) and weak acid cation exchange resin (hereinafter referred to as weak cation resin), or similarly strong basic anion exchange resin (Hereinafter referred to as strong type anion resin) and weakly basic anion exchange resin (hereinafter referred to as weak type anion resin) are combined to make water flow from weak type to strong type and regeneration from strong type to weak type. Compared with the case of using a single resin,
In addition, regenerant can be saved.

The countercurrent type is divided into one for performing descending circulating water and ascending circulating medicine and one for performing ascending circulating water and descending circulating medicine. In order to exert the features of the countercurrent method in any of the methods, during the process of upflow, that is, during the flow of medicine in the descending circulating water / updrafting medicine method, during the passage of water in the rising circulating water / downdrafting medicine method, It is necessary to maintain the ion exchange resin in the fixed bed. In the ascending-flow water / down-flowing chemical method, the fixed bed, that is, the ion exchange zone is disturbed due to the interruption of the water flow, and the treated water quality is likely to deteriorate. Further, a special operation is required for discharging the suspended solids accumulated in the ion-exchange resin in flowing water and for transferring the resin for backwashing. On the other hand, in the descending circulating water / ascending circulating medicine method, the water quality is not deteriorated due to the interruption of the circulating water, so that there is an advantage that the ON-OFF operation can be freely performed at the time of water sampling. In addition, in a multi-layer bed using weak ion exchange resin and strong ion exchange resin, the weak ion exchange resin has a lower specific gravity, and the inside of the resin tower is physically The multi-layer bed cannot be applied without partitioning, whereas the descending flowing water / upflowing drug has a feature that it can be separated into two layers by the difference in specific gravity even if there is no physical partition (intermediate partition wall).

However, when the descending circulating water and ascending circulating drug methods are carried out without a physical partition (intermediate partition wall), there are the following problems. (1) The cation tower is used in a combination of [weak cation resin + strong cation resin], and the anion tower is used in a combination of [weak anion resin + strong anion resin]. There is a considerable difference in specific gravity between the weak type and the strong type in the regenerated type, so that the regenerated type can be separated. <Specific gravity of each resin> Weak cation resin: 1.13 to 1.18 Strong cation resin: 1.25 to 1.30 Weak anion resin: 1.04 Strong anion resin: 1.08 to 1. 10

However, when the salt-type or weak-type anion resin adsorbs an organic substance, the difference in specific gravity is almost eliminated, mixing of the weak-type and strong-type progresses, and finally problems such as poor quality of treated water and inability to collect water amount occur. . The following methods have been proposed as measures against this. A resin with a narrow particle size distribution (preferably a uniform particle size) is used instead of a conventional resin with a wide particle size distribution, and a strong ionic resin has a large particle size and a weak ionic resin has a small particle size. And improve the separation. As shown in FIG. 2, the regeneration is generally performed by arranging an intermediate water collecting pipe 26 on the upper part of the weak ion exchange resin 8 and opening the valve 27 from the tower upper part of the resin at the lower part of the intermediate water collecting pipe to obtain pressurized water or pressurized air. Is introduced to form a fixed bed, and the drug is passed in an upward flow. Then, the recycled waste liquid discharge valve 25 is opened to discharge the recycled waste liquid.

(2) Ion exchange resins tend to contract when they come into contact with regenerants, especially weak ion exchange resins during up-flow drugs. This shrinkage phenomenon is mainly because the weak ion-exchange resin is easily regenerated, so that the ionic form is rapidly converted from the salt form to the regenerated form (RH, R-OH). Table 1 shows examples of volume changes between the salt form and the regenerated form.

[Table 1]

Strong ion exchange resins are small in salt form and increase in volume in regenerated form. On the other hand, weak ion-exchange resins increase in volume when they are regenerated and small in salt form. That is, at the time of regeneration, the strong ion exchange resin causes some shrinkage due to the regeneration liquid,
In addition, even if the property of being difficult to be regenerated is taken into consideration, generally, after regeneration, about 4 to 10% of that before regeneration tends to swell. However, since weak ion exchange resins are easily regenerated, the volume of the water after regeneration is generally about the same as that before regeneration, although it varies depending on the ionic composition of the raw water that is passed because it converts nearly 100% from the salt form to the regenerated form. The volume is reduced by 20 to 30%.

On the other hand, when water is collected, the weak ion exchange resin is converted from the regenerated form to the salt form, so that the volume thereof swells and the resin layer is apt to be consolidated. On the contrary, since the strong ion exchange resin has a volume shrinkage direction, it can be said that compaction hardly occurs. As described above, the change in the ionic form of the weak-type ion exchange resin is large and remarkably occurs at the time of regeneration, so that voids are easily formed near the separation interface between the weak-type and strong-type and the resin is partially fluidized. However, the risk of uneven distribution (channeling) of the regenerant increases. And the quality of treated water often deteriorates.

(3) In order to solve the problems described in (2), various measures have been conventionally made. In order to prevent fluidization due to contraction of the ion exchange resin and to achieve uniform dispersion of the regenerant, it is necessary to suspend the medicine exchange during the medicine passage, allow the contracted ion exchange resin to settle, and then restart the medicine passage. A method of repeating the method once or a time, a method of reducing the influence of contraction by passing a low concentration regenerant at a low flow rate, and a method of increasing the amount of pressurized water or air introduced from above have been proposed. By these methods, fluidization of the ion exchange resin layer can be prevented for the time being. However, there are disadvantages such as extension of regeneration time due to complication of regeneration operation, increase of amount of waste liquid for regeneration, complication of apparatus itself, increase of regeneration cost, and the like.

(4) As shown in FIG. 2, the intermediate water collecting pipe 26
In this case, the ineffective resin 28 on the upper part of the intermediate water collecting pipe 26 is backwashed each time, and the resin on the lower part of the intermediate water collecting pipe 26 is not backwashed during normal regeneration. However, if the operation is continued in this state, accumulation of suspended solids and consolidation of resin particles occur. Therefore, normally, [regeneration-water sampling], once every 7 to 20 times, the entire layer of ion exchange resin is removed from the bottom. I'm backwashing. When all layers are backwashed, the ion exchange zone is disturbed, so that a regenerant amount of 2 to 2.5 times that of normal regeneration is required. Then, the weak ion exchange resin is backwashed and separated under the condition that most of it is regenerated,
It is necessary to return to the condition where the initial weak type and strong type are sufficiently separated.

(5) However, as described above, (regeneration-water sampling)
As the process proceeds, the mixing of the weak type and the strong type progresses particularly as the column diameter increases, and channeling during drug passing, deterioration of treated water quality, and insufficient water intake often occur. In order to avoid this, considering the mixing from the beginning of design, the required amount of 2
Often, 0 to 30% more resin is filled in advance. That is, such a system is unsuitable as the tower diameter becomes larger and cannot be adopted in the actual situation. (6) Since the intermediate water collection pipe 26 is inside the resin layer, a damage accident may occur due to repeated load due to pressure loss during water collection.

(7) The method of providing an intermediate partition wall in the tower has been put to practical use in a countercurrent type ion exchange tower in which ascending flowing water and descending flowing chemicals are used. In this system, as shown in FIG. 3, the tower is basically provided with two intermediate partition walls 2 and the tower is divided into three chambers. The lower chamber 21 is filled with the weak ion exchange resin 8, and the intermediate chamber 29 and the upper chamber 22 are filled with the strong ion exchange resin 5. And the inert resin 30 in all three rooms
have. The weak ion exchange resin 8 in the lower chamber 21 is
It is used to some extent in fluidized bed conditions, and there is little accumulation of suspended solids. The intermediate chamber 29 also has a freeboard 33 in order to pass water under a certain fluidized bed condition. The upper chamber 22 is filled with the strong ion exchange resin 5 to form a fixed layer. When the upper chamber 22 is to be backwashed, the resin is transferred to the freeboard 33 of the intermediate chamber 29 containing the same resin, and the freeboard for backwashing is secured and backwashed.

Then, after the back washing is completed, the resin is put in the intermediate chamber 29 again.
Is re-transferred from the upper chamber to the upper chamber 22 to be filled. The following disadvantages occur under such tower design and operating conditions. a) The internal structure of the tower is complicated. b) The tower height becomes high. c) Since resin is transferred and retransferred between the upper chamber and the intermediate chamber, it takes time to regenerate the resin. The regeneration time for backwashing in this system is usually 5 to 6 hours. In addition, piping for resin transfer,
A valve is also required, and resin wear is likely to occur. d) The nozzle with a slit of 0.2 to 0.5 mm used as the intermediate partition wall is easily clogged by the suspended substance or the like. As described above, the up-flowing water and down-flowing drug methods have good regeneration efficiency, but have a complicated apparatus and have many demerits in maintenance. On the other hand, using the weak and strong ion-exchange resins in the same column without intermediate partition walls in the descending circulating water and ascending circulating chemical systems is to achieve more stable operation as the column diameter increases. Has turned out to be quite difficult.

[0014]

DISCLOSURE OF THE INVENTION The present invention is an improvement of the downward flow water / up flow chemical system, which has the above-mentioned problems, namely, extension of the regeneration time, increase of the amount of waste liquid for regeneration, weak and strong ion exchange resins. Countercurrent ion exchange that solves various problems during mixing, drug passing, and complication of equipment and regeneration operation, can be regenerated in a short time using a simple and compact ion exchange tower, and can be operated stably. It is intended to provide a method for regenerating a tower.

[0015]

In order to solve the above problems, according to the present invention, an ion exchange tower is provided with an intermediate partition wall near the middle portion through which water but not ion exchange resin is passed to form a lower chamber and an upper chamber. The lower chamber is filled with strong type ion exchange resin and the upper chamber is filled with weak type ion exchange resin, and the freeboard in the lower chamber is 2 to 15%, and the freeboard in the upper chamber is 1
0 to 30% larger than the lower chamber, and each freeboard was filled with an inert resin with a specific gravity of 1.0 or less.
In the method of regenerating a countercurrent ion exchange tower for descending circulating water and ascending circulating agent, the following steps (a) to (e) are sequentially performed to regenerate the resin. (A) Most of the ion-exchange resin is pressed against the inert resin by high-flow backwashing from a lower water collecting device provided at the lower part of the tower,
A high flow rate backwashing step in which a suspended material accumulated during water passage is discharged from an upper water collecting device provided in the upper part of the tower via an inert resin, and a fixed bed of ion exchange resin is formed, (b) high flow rate A slower than the backwash step, and a replenishing step in which the regenerant is passed from the lower water collecting device in an upward flow at a flow rate necessary to maintain the fixed bed formed in (a), (c) most of the above An extrusion process in which treated water is passed in an upward flow from the lower water collecting device at a flow rate that can maintain a fixed bed, and the remaining regenerant is effectively used,
(D) A low flow rate backwashing step in which raw water or treated water is introduced at a low flow rate from under the intermediate partition wall and only the upper chamber is backwashed, and (e) a downward flow of water is passed from the upper water collecting device for washing. Washing process.

In the above regenerating method, since the suspended substance is discharged from the upper water collecting device again after the low flow backwashing process of (d), the high flow backwashing process of (a) is performed in the lower water collecting device, or Do from just below the middle partition. Then, water was introduced from the upper water collecting device, and the wash drain valve of the lower water collecting device was opened,
You may implement the resin moving process which moves the formed fixed bed to the lower part of a tower using the descending flow of water. In the low flow rate backwashing step (d), the wash drain valve connected to the lower water collecting device is opened, and raw water or treated water is passed through the strong ion exchange resin for a short time to form a fixed bed. The strong ion exchange resin may be moved to the lower part of the tower. Further, in the present invention, after the completion of water collection, only the upper chamber filled with the weak ion exchange resin having the increased pressure loss due to the trapping of the suspended substance or the consolidation is treated with the raw water or It is also possible to introduce treated water, carry out low-velocity backwashing, loosen the weak ion-exchange resin, and then carry out the above-mentioned regeneration method. In this case, the high flow rate backwashing step is performed after the extrusion step of (c), but this high flow rate backwashing step may be omitted when the suspended solids are small. As described above, in the present invention, the intermediate partition is provided, the weak ion-exchange resin is filled in the upper chamber, the strong ion-exchange resin is filled in the lower chamber, and the tower structure has no mixing conditions of both resins at all, The problems of the conventional method are solved by applying the suitable regeneration process of the present invention.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. In the present invention, water collecting devices 3 and 4 are provided above and below the ion exchange tower, and an intermediate partition wall 2 that allows water to pass through but does not allow the ion exchange resins 5 and 8 to pass is provided near the middle portion of the ion exchange tower 1. The upper chamber 22 is divided into two chambers. In the lower chamber 21, the strong ion exchange resin 5 is filled on the upper part of the lower water collecting device 4, and some freeboard 6 is placed on the strong ion exchange resin 5.
100 to 400 mm of an inert resin 7 having a larger particle size than the strong ion exchange resin 5 and a size capable of holding the strong ion exchange resin and a specific gravity of 1.0 or less. Upper chamber 2
2 also has a weak ion exchange resin 8 on the upper part of the intermediate partition wall 2,
Inert resin 10 is filled through some freeboard 9. The upper and lower water collecting devices 3 and 4 may be of a perforated plate type with nozzles or a perforated pipe type. The intermediate partition 2 has a thickness of 0.
A perforated plate with a nozzle having a slit of about 5 mm or a flat screen such as SUS316 as a material may be used.

The upper water collecting device 3 has a raw water inflow valve 11, the recycled wastewater discharging valve 12 and the lower water collecting device 4 has a treated water outflow valve 1.
3, a backwash water inflow valve 14, a regenerant / extruded water inflow valve 15, a wash drainage valve 16 are connected, and an air vent valve 23 is also provided at the top of the tower. Further, on the wall of the ion exchange tower, a manual ball valve 1 is provided so that the amount of ion exchange resin and the amount of inert resin can be adjusted.
7, valve 18, valve 19 and valve 20 are provided. Sight glasses, manholes, etc. will be provided at appropriate places. Sight glass has at least valve 17, valve 18, valve 1
9. The valve 20 is provided at a position where the resin surface can be adjusted. The manhole is preferably provided at the top of the tower, the bottom of the tower, the lower chamber 21 and the upper chamber 22 near the resin surface. The conventional countercurrent type having an intermediate water collecting pipe usually needs to have a backwash freeboard 33 of 75 to 100% as shown in FIG. The countercurrent type of resin-filled type does not have a freeboard, but it requires a separate backwash tower.In the conventional countercurrent type, the device configuration, piping, and operation method are complicated. There is. In addition, the volume in the tower is not effectively utilized because the freeboard is large.

In the ion exchange column used in the present invention,
An intermediate partition 2 is required, but freeboards 6 and 9 are
It can be made much smaller, and even if the inert resins 7 and 10 are added, the internal volume of the tower is effectively utilized, the tower height is lowered, and it is compact. What is important in the construction of the present invention is how much the freeboards 6 and 9 are made.
In the present invention, as a result of experiments, the freeboard 6 filled with the strong ion exchange resin 5 in the lower chamber 21 shows that the strong cation resin and the strong anion resin 2 to 2 at the time of maximum swelling of each resin, that is, regenerative filling. 15%. Preferably 2
It may be as small as 8%. If this freeboard 6 is taken to be smaller than the maximum swell, it will swell the most, that is, it will be regenerated by 2-3 times, and the regenerated form will increase.
If a regenerated resin is used and there is a margin of 2 to 15% that causes inconvenience when exchanging and replenishing, it is easy to maintain and prevent the swelling pressure of the resin from being applied to the tower itself.
The risk of destroying the tower itself and crushing the resin itself can be avoided.

In the present invention, after the completion of extrusion, the cleaning drain valve 1 for a short time of 1 to 3 minutes at the initial stage of low flow rate backwashing of the upper chamber.
In order to reduce the disturbance of the ion exchange zone, the fixed layer of the strong ion exchange resin 5 which was pressed against the inert resin 7 by opening 6 is used as raw water or treated water by a downward flow,
It is moved below the lower chamber 21. The shorter the moving distance, that is, the smaller the proportion of the freeboard 6, the smaller the disorder of the ion exchange zone. As in the present invention, when the strong ion exchange resin 5 is not allowed to move downward and the resin is allowed to settle freely, the larger the freeboard and the larger the column diameter, the greater the disorder of the ion exchange zone and the greater the treated water quality. The risk of deterioration and shortage of water is increased, resulting in lack of operational stability. If the strong ion-exchange resin 5 is forcibly moved in this way, there is a concern that the resin may not be consolidated (leading to an increase in pressure loss) due to the amount of swelling in the drug passing step and the extrusion step. However, as a result of the experiment, the practical tower diameter is large, 50
When it is 0φ or more, the ratio L / D of the packed bed height L and the tower diameter D is 2 to
It was found that if it is 3 or less, no consolidation due to swelling of the resin occurs at the end of the extrusion process.

This may be due to the following reasons. In order to carry out the flow-through step and the extrusion step at a low flow rate such that the fixed bed formed in the high-flow rate backwash step carried out in the present invention is performed, the volume of the swelled portion of this strong ion exchange resin is It is considered that the swelling pressure is released because the downward force acts not on the lateral direction of the tower but also on the downward direction. The preferable value of the free board 6 of the strong ion exchange resin 5 described above, 2 to 8%, is practically the regenerated form after the resin is regenerated, and even under the condition that the salt form is small,
Even when the water stops due to a valve failure at the end of the extrusion process, etc., and the resin falls freely and is slowly filled in the lower chamber, there is a margin to check the failure, strong ion exchange resin 5 It is the value of the condition that it is easy to check the level of the inert resin 7, etc., and replace and replenish it. The upper chamber 22 of the present invention is filled with the weak ion exchange resin 8. The most important issue is how much the freeboard 9 of the weak ion exchange resin 8 of the cation tower into which the raw water first flows is used.

The volume change of the weak cation resin is considerably different depending on the type of resin and the type of loaded ions. <Example of ionic volume change> RH → R-Ca: +5 to + 15% RH → R-Na: +40 to + 55% Therefore, consider the ionic composition of raw water and decide the freeboard. There is a need. If the hardness (Ca + Mg) of raw water is higher than M-alkalinity, the weak cation resin 8 is
Most of the ionic forms at the end of water sampling are [R-Ca + R-Mg]
And partially contains R-Na and a regenerated form (RH). When the hardness of the raw water is smaller than M-alkalinity, the hardness of the raw water is R-Ca and R-Mg, but NaHCO ₃ corresponding to [M alkalinity-hardness]
R-Na is also considerably produced because the ion exchange is also performed. In this case, R-Ca, R-Mg, R-Na, depending on the ion composition of raw water and the loading amount of each ion in one cycle,
The amount of unused RH produced is determined.

Therefore, the freeboard 9 of the weak cation resin 8 is based on the average swelling volume corresponding to the raw water quality under the condition of eliminating the consolidation at the end of one cycle of water sampling, and changes in water quality, that is, the end of water sampling. In consideration of the loaded ion type and the amount of each ion type produced, a value slightly larger than the average swelling volume after the end of water sampling is set as the reference maximum swelling volume. In this way, 10% to 30%, preferably 10% to 20% of the determined standard maximum swelling volume is used as the actual freeboard 9.
It is important to check the resin level at the end of one cycle of water sampling and periodically confirm that the free board 9 of 10 to 20% as described above is secured. Then, in the present invention, the upper chamber is backwashed every cycle so as to have a wide adaptability, so that the suspended substance trapped in the weak cation resin 8 or the consolidation of the resin itself is eliminated. For example, when turbidity of about 0.5 to 3 degrees flows in or when high-speed water sampling of 25 to 45 m / h is performed, the ionic form is converted from the regenerated form to a fixed salt form according to the ionic composition of the raw water. Therefore, it tends to swell and is easily consolidated. As a result, the inflowing suspended matter from the surface is 4
It penetrates up to about 00 to 600 mm, but it is known that the amount of penetration deeper than that is extremely small. Therefore, the amount of the strong cation resin 5 entering the lower chamber 21 is extremely small.

After the completion of water collection, the weak cationic resin 8 in the upper chamber 22 is backwashed every cycle, and the suspended substances trapped are discharged.
It can be said that eliminating the consolidation is indispensable for stable operation. In the present invention, this backwash is carried out under the condition that the weak cation resin 8 after the completion of extrusion and the extrusion process is regenerated and the volume is minimized, that is, the freeboard 9 is maximized. The proportion of the free board 9 at this time is as shown in Table 2, for example.

[Table 2]

[0025] In the case of the reproduction type as described above,
There is room in the freeboard, and depending on the water temperature, the type of resin, and the ratio of the ionic form, a low flow rate backwash process of LV 5-10 m / h is performed for 5 to 15 minutes to eliminate consolidation and discharge suspended solids. I do. As the backwash water, raw water or treated water is used and the low flow rate backwash valve 24 of the backwash water introduction pipe 34 provided immediately below the intermediate partition wall 2 is opened. When the tower diameter is small, the backwash water introduction pipe 34 may not be provided, and the low flow rate backwash valve 24 provided in the pipe directly connected to the tower wall may be opened. Then, after performing a calming process in which all the valves are closed, the raw water inflow valve 11 and the cleaning drain valve 16 are opened to perform the cleaning process. When the suspended solids cannot be sufficiently discharged by this low flow rate backwashing process, the regeneration wastewater discharge valve 12 and the low flow rate backwash valve 24 are then opened to increase the amount of water so that the upper chamber of LV 16-26 m / h or higher is obtained. The high flow rate backwash step may be performed for 2 to 3 minutes.

Alternatively, the backwash water inflow valve 14 may be opened from the water collecting device 4 at the bottom of the tower. In this case, treated water is used as backwash water. Performing the high flow rate backwashing process from the lower part of the tower is useful for discharging the suspended substances accumulated in the strong cation resin 5, the inert resin 7, or the crushed products of these resins. The regeneration time will be slightly longer, but the operation will be more stable. These upper chamber 22 and lower chamber 21
When the high flow rate backwashing process was performed for both, the raw water inflow valve 11 and the washing and draining valve 16 were then opened, and the weak and strong ion exchange resins 5 and 8 that became the fixed bed were again towered by the descending flow of water. An all resin downward moving step of forming a fixed layer at the bottom is required. Since this process is completed in 0.5 to 2 minutes,
The air vent valve 23 and the cleaning drain valve 16 at the top of the tower may be opened. Then, the cleaning process is performed thereafter.

Even in the case of the weak anion resin 8 of the anion tower, the freeboard 9 thereof varies depending on the ionic composition of the raw water and the load thereof, as in the weak cation resin. Since weak anion resin 8 is generally often used acidic soft water after decarbonation tower as raw water, its load ionic form is R-Cl, the R-SO ₄ mainly. Further, in the R-HCO _{3 type,} there are some resins which show a considerably large swelling ratio similar to the weak type cationic resin. There is also a device for loading HCO ₃ ⁻ and CO ₂ without providing a decarbonation tower. Therefore, similar to the weak cation resin, the water quality changes based on the average swelling volume after the end of water sampling for one cycle under the condition that the consolidation is eliminated, that is, the load ion type at the end of water sampling, and the production amount of each ion type. Considering the above, it is preferable that the reference maximum swelling volume be a value slightly larger than the average swelling volume at the end of water sampling.

The actual freeboard 9 is 5 to 30%, preferably 10 to 20% of the standard maximum swelling volume determined in this way. Then, it is important to regularly check the resin level at the end of one cycle of water sampling to confirm that the freeboard 9 is properly maintained. Further, in the case of the weak anion resin 8, unlike the case of the weak cation resin, the inflow of the suspended substance is extremely small, so that the main purpose is to eliminate the consolidation after the end of water sampling. For this purpose, LV4-8m /
The low flow rate backwashing process is performed for about 5 to 10 minutes at h. Then, after that, like the cation tower, the step of adjusting the upper chamber 22 is performed.
Subsequently, the cleaning process for the upper chamber 22 and the lower chamber 21 may be performed. If necessary, the high flow rate backwashing process is performed again. In the present invention, after the completion of water sampling, the low flow rate backwashing step is mainly performed to eliminate the consolidation of the weak ion exchange resin 8 in the upper chamber 22, and the basic step of the present invention is then applied to suspend the suspension. A sufficiently high regeneration efficiency can be obtained with the discharge of the substance.

In this case, regarding the weak cation resin,
Transfer of suspended solids captured upwards with deconsolidation,
For the purpose of drainage, 10 to 10% of the average swelling volume after the end of water sampling
The amounts of the weak cation resin 8 and the inert resin 10 are adjusted so as to obtain a free board of 30%, preferably 15 to 30%. And, low flow backwashing of LV 4-8 m / h 5
Do 10 minutes. Then, the sedimentation step is performed for about 5 minutes. In this case, since the freeboard ratio is small, a sufficient backwashing flow rate cannot be obtained, and the main purpose is to eliminate the consolidation, but the upward movement to the suspended substance is also performed. Discharge of suspended matter is achieved mainly by performing a subsequent step, a high flow rate backwash step. The weak type anion resin is also made into the same freeboard as the weak type cation resin, and the low flow rate backwashing of LV 3 to 6 m / h is performed for 5 to 10 minutes to eliminate the consolidation of the resin. Then, it is regenerated like the cation tower. Furthermore,
In order to effectively perform the low flow rate backwashing process of these upper chambers 22, air is mixed into the backwash water to make the weak ion exchange resin filled into the air scrubbing state, and then the normal low flow rate backwashing is performed. You may perform a process.

The material of the inert resin used in the present invention is, for example, polypropylene having a specific gravity of 1.0 or less, has no residual regenerant, is easy to wash, and can absorb the swelling pressure of the ion exchange resin to some extent. Any elastic material and shape may be used. The particle size of the ion-exchange resin is usually 0.65 m so that the suspended solids can be easily discharged.
Since it is about m, it may be about 2 to 8 times that. That is, the particle size of the inert resin in the upper chamber 22 and the lower chamber 21 is approximately 1.0 to 5.0 mmφ, and preferably approximately 2 to 4 mmφ. If the particle size is too small, it becomes difficult to discharge the trapped suspended matter. On the other hand, if it is too large, the ion exchange resins 5 and 8 will pass through the inert resins 7 and 10 when passing an upward flow, during extrusion, etc., to prevent the water collecting port (slit) of the upper water collecting device 3 and to set the set flow rate. It becomes difficult to flow.

The layer height of the inert resins 7 and 10 is 100.
It may be up to 400 mm, but when the tower diameter is large, it should be set to a large value in consideration of whether or not the inert resin layer becomes flat uniformly. However, be aware that if the bed height is too large, it will be difficult to discharge suspended substances during high-speed backwash. Crushing the inert resin itself also causes clogging, so the entire amount of the inert resin is discharged at every regular inspection, the tower is inspected and crushed, and the powdered inert resin is removed and refilled. It is also necessary to consider what to do. The state of discharge of suspended substances during the high-flow-rate backwash step in the present invention is completely different from the conventional method. Most of the suspended solids from the raw water act as a load on the cation column and very little on the anion column, so an example of a cation column is representatively shown.

[0032]

The present invention will be specifically described below with reference to examples. Example 1 In an ion exchange column having an inner diameter of 300φ × 2460H (body length),
Dowex HCR-W2 as a strong cation resin in the lower chamber is RH type 1065 mm, Levatit CNP-80 as a weak cation resin in the upper chamber is 675 mm in RH type (R-Ca type) 740 mm). The freeboard in the lower chamber is 65 mm (6.1% for RH type), and the inert resin is polypropylene 2.
Granules of 5 to 3.5 mm were packed at a layer height of 150 mm.

The freeboard of the upper chamber is 260 mm,
The same inert resin as the lower chamber was filled to 150 mm. To this ion exchange column, 14 mg / l of a powder ion resin and 1 mg / l of kaolin were added and tap water free of free chlorine was passed at 1200 l / h for 2.5 hours. Then, after passing water, high-speed backwash was performed for 3 minutes at LV 28 m / h. An example of the effect under this condition is shown in FIG. The amount of backwash waste water is about 100 liters, and after 20-40 seconds of high-speed backwash,
The value of the suspended substance was 5000 mg / liter or more at maximum. Then, it rapidly decreased, and after 2 minutes, it became 10 mg / liter or less. Total suspended matter removal rate is 90-9
9% was obtained.

Comparative Example 1 Dowex, HGR-W2 as RH type was used as a strong cation resin in the same column as in Example 1 without intermediate partition walls.
064mm, Levatit CNP as weak cationic resin
-80 was filled with R-H type for 675 mm. Then, a backwash tower of 300φ × 1000H was provided above the ion exchange tower. After the suspension substance was loaded under the same conditions as in Example 1, general backwashing was performed for 15 minutes at LV 13 m / h.
The change in the concentration of the suspension in the backwash drainage under these conditions is shown in FIG. The total amount of suspended matter is 9 even with normal backwash.
0 to 97% removed. However, the backwash drainage is 23
The concentration was as high as 0 liter / c, and the concentration of suspended substances in the backwash wastewater was about 340 mg / liter after 2-3 minutes of backwash, but it was considerably lower than in Example 1. Then, the decrease thereafter was gentle and even after 15 minutes, it was around 60 mg / liter.

It was found that the high flow rate backwashing method can discharge suspended substances in a shorter time than the conventional method. The amount of backwash drainage was also reduced to about 1/2. Table 3 shows a typical summary of the regeneration process of the present invention. In Method B shown in Table 3, after the upper chamber low-flow rate backwashing step, the 7-step high-flow rate backwashing may be carried out immediately without the 6th step upper chamber deposition. Similarly C
Also in the method, high-flow backwashing may be carried out immediately by omitting the two-step upper chamber deposition. This is because the suspended substance is moved upward and the weak resin is sized by the backwashing with the low velocity of the upper chamber in the previous step, and the necessity of carrying out the settling step is small.

[0036]

[Table 3]

In the pure water apparatus, the anion column is washed with the treated water (acidic soft water) of the cation column after the washing of the cation column. Therefore, the total reproduction time is 10 to 15 minutes longer than the reproduction time shown in Table 3. Therefore, the total reproduction time according to the present invention is about 90 to 140 minutes. The method using the conventional intermediate water collecting pipe is 150-
It is considerably shorter than 200 minutes. Ascending circulation water, downward circulation medicine method is usually 90 to 150 minutes,
Even though it takes 300 to 360 minutes at the time of total backwashing, in the method of the present invention, the weak ion exchange resin in the upper chamber, which is easy to regenerate, is completely backwashed in each cycle, and the strong ion exchange in the lower chamber is difficult to regenerate. Since the process is a regeneration process that does not require total backwashing of the resin, it is always performed for a short period of time. Regeneration efficiency is 80% at every cycle because weak ion exchange resin is easy to regenerate even if it is completely backwashed.
Values of ˜90% or higher are obtained.

Example 2 Method A in Table 3 was used. Inner diameter 1200φ x 250
In the lower chamber of the 0H (body length) ion exchange column, HCR-W2 as a strong cation resin is 1065 mm in RH type, and in the upper chamber through an intermediate partition with a nozzle, Levatit CNP80 is used as a weak cation resin. -Filled 675 mm with H form. Upper and lower water collecting device: Perforated plate type with nozzle Freeboard: Upper chamber 24% (for average swelling volume layer height of 750 mm at the end of water sampling) Lower chamber 6.1% (for regenerated type) Inert resin : Polypropylene 2.5-3.5 mmφ Upper chamber 190 mm Lower chamber 190 mm Regeneration level: 74 g / liter-R (strong cationic resin R-Na)

Raw water: River water Coagulated filtered water Treatment concentration: 0.5 degrees or less Table 4 shows the raw water ionic composition.

[Table 4]

Table 5 shows the treatment conditions in the regeneration step (cation tower).

[Table 5]

[Results] 1) Water sampling time: 18.8 hours, water sampling 30 m ³ / h 2) Water sampling amount: 564 m ³ / c Anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 88.5 % 4) Treated water quality: 0.2 to 5.0 μS / cm 5) Regeneration time: 84 minutes 6) Freeboard at low flow rate in upper chamber%: Approx. 35%

Example 3 The method B of Table 3 was carried out as follows. Using the ion exchange tower of Example 2, the suspended matter of river bottom mud was injected into raw water in the range of 0.5 to 2 degrees in turbidity. Table 6 shows the treatment conditions of the regeneration step (cation tower).

[Table 6]

[Results] 1) Water sampling time: 18.7 hours, water sampling 30 m ³ / h 2) Water sampling amount: 561 m ³ , anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 88.1% 4) Treated water quality: 0.2-5.0 μS / cm 5) Regeneration time: 87 minutes 6) Freeboard at low flow rate in upper chamber%: Approximately 35% 7) No increase in pressure loss was observed during the cycle. It was

Example 4 Method C in Table 3 was carried out under the conditions of Example 3. Table 7 shows the processing conditions of the regeneration step (cation tower).

[Table 7]

[Results] 1) Water sampling time: 18.7 hours, water sampling 30 m ³ / h 2) Water sampling: 561 m ³ , anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 88.1% 4) Treated water quality: 0.2-5.0 μS / cm 5) Regeneration time: 83 minutes 6) Freeboard at low flow rate in upper chamber%: Approximately 24% 7) No increase in pressure loss was observed during the cycle. It was

Example 5 Under the conditions of Example 4, after the upper chamber low-flow backwashing process, the upper chamber sedimentation process was omitted and the high-velocity backwashing process was immediately performed from the lower chamber water device using pure water. That is, in Table 7, the upper chamber deposition in the second step was omitted. [Results] The same results as in Example 4 were obtained. The regeneration time was 78 minutes.

Example 6 The treated water of Example 4 was decarbonated and passed through the anion tower as raw water, and its performance was confirmed by the method C in Table 3. Tower: Inner diameter 1300φ × 3500 (body length) With intermediate partition Upper and lower water collecting device: Perforated plate system with nozzle Upper chamber: Weak anion resin, Dowex MWA-1 R-OH type 1500 liters were filled. Free board: R-OH: 30.6% (350 mm) R-Cl: 25% (350 mm) Inert resin: 190 mm Lower chamber: Strong anion resin, Marathon A 1500 liters of R-OH type were filled. Freeboard: Approx. 6.1% (70 mm) Inert resin: 190 mm Regenerator amount: 72 kg / C 100% NaOH Regeneration level: 56.2 g / liter-R (strong anion resin R-Cl) The processing conditions of (anion tower) are shown.

[0048]

[Table 8]

[Results] 1) Water sampling time: 18.7 hours, water sampling 30 m ³ / h 2) Water sampling amount: 561 m ³ , anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 89.7% 4) Treated water quality: 0.2 to 5.0 μS / cm, silica 0.01 to 0.03 mg / liter 5) Regeneration time: 102 minutes 6) Freeboard% at low flow rate in upper chamber: Approx. 25% 7) Pressure No increase in losses was seen as the cycle progressed. 8) It was a break in the Kachin tower, and the anion tower was in a state where water could be further collected.

[0050]

INDUSTRIAL APPLICABILITY According to the present invention, the ion exchange column is divided into two chambers by an intermediate partition through which water is passed but not ion exchange resin is passed, and a strong ion exchange resin is placed in the lower chamber and a weak ion exchange resin is placed in the upper chamber. Filled and recycled freeboard in lower chamber 2
〜15%, the freeboard of the upper chamber is increased to 10-30% of the standard maximum swelling volume after completion of water collection, and the weak ion exchange resin in the upper chamber is backwashed after every cycle, after regeneration, or before regeneration. The regeneration process typified by Table 3 is applied to a countercurrent ion exchange tower of downward flow water and upward flow regeneration system. According to the regeneration method of the present invention, there is no intermediate partition wall, which is a drawback of the conventional method having an intermediate water collecting device, that is, the extension of the regeneration time, the increase of the amount of waste liquid for regeneration, the weak type, the mixing of the strong type ion exchange resin, and The complication of the device / regeneration operation is eliminated, and short-time regeneration, reduction of regeneration cost, and stable operation can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an ion exchange column showing an example of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a conventional method using an intermediate water collection method.

FIG. 3 is a schematic configuration diagram showing an example of a conventional method of ascending circulation water and descending flow regeneration.

FIG. 4 is a graph showing changes over time in the concentration of suspended substances in backwash wastewater.

FIG. 5 is a graph showing changes over time in the concentration of suspended substances in backwash waste water in a comparative example.

[Explanation of symbols]

1: Ion exchange tower, 2: Intermediate partition wall, 3: Upper water collecting device,
4: Lower water collecting device, 5: Strong type ion exchange resin, 6: Lower chamber freeboard, 7: Lower chamber inert resin, 8: Weak ion exchange resin, 9: Upper chamber freeboard, 10: Upper chamber free Active resin, 11: Raw water inflow valve, 12: Recycled wastewater discharge valve,
13: Treated water outflow valve, 14: Backwash water inflow valve, 15: Regenerant / extruded water inflow valve, 16: Wash drainage valve, 17: Strong ion exchange resin amount adjusting valve, 18: Lower chamber inert resin amount Adjusting valve, 19: Weak ion exchange resin amount adjusting valve, 20: Upper chamber inert resin amount adjusting valve, 21: Lower chamber, 22: Upper chamber, 2
3: Air vent valve, 24: Low flow rate backwash valve, 25: Recycled wastewater discharge valve, 26: Intermediate water collecting device, 27: Pressurized water introduction valve, 2
8: Ineffective resin, 29: Backwash water introduction valve, 30: Inert resin, 31: Resin transfer valve, 32: Resin transfer water valve, 33:
Free board, 34: Backwash water introduction pipe

Claims (4)

[Claims] 1. An ion exchange column is divided into two chambers, a lower chamber and an upper chamber, by providing an intermediate partition near the middle portion through which water is passed but not through the ion exchange resin, and a strong ion exchange resin is provided in the lower chamber.
The upper chamber is filled with weak ion exchange resin, the freeboard in the lower chamber is 2 to 15%, and the freeboard in the upper chamber is 10 to 10.
In the method of regenerating a countercurrent ion exchange tower for descending flowing water and ascending flowing chemicals, which is 30% larger than the lower chamber, and the upper part of each freeboard is filled with an inert resin having a specific gravity of 1.0 or less. A method for regenerating a countercurrent ion exchange tower, characterized in that the resin is regenerated by sequentially performing steps (a) to (e). (A) Most of the ion-exchange resin is pressed against the inert resin by high-flow backwashing from a lower water collecting device provided at the lower part of the tower,
A high-flow-rate backwashing step in which a suspended material accumulated during water passage is discharged from an upper water collecting device provided at the upper part of the tower via an inert resin, and a fixed bed of ion-exchange resin is formed, (b) high-flow rate A slower than the backwash step, and a replenishing step in which the regenerant is passed from the lower water collecting device in an upward flow at a flow rate necessary to maintain the fixed bed formed in (a), (c) most of the above An extrusion process in which treated water is passed in an upward flow from the lower water collecting device at a flow rate that can maintain a fixed bed, and the remaining regenerant is effectively used,
(D) Low-flow backwashing step in which raw water or treated water is introduced at a low flow rate from below the intermediate partition wall, and only the upper chamber is backwashed, (e) water is passed in a downward flow from the upper water collecting device for washing. Washing process. 2. After the low flow rate backwashing step of (d) above,
In order to discharge the suspended solids from the upper water collecting device, the above (a)
The high flow rate backwashing process is carried out from the lower water collecting device or directly below the intermediate partition wall, then water is introduced from the upper water collecting device, the washing drain valve of the lower water collecting device is opened, and the downward flow of water is reduced. The method for regenerating a countercurrent ion exchange column according to claim 1, wherein a resin transfer step of moving the formed fixed bed to the lower part of the column is carried out. 3. In the low flow rate backwashing step of (d) above,
Open the washing drain valve connected to the lower water collecting device for a short time,
The countercurrent ion exchange according to claim 1 or 2, wherein raw water or treated water is passed through a strong ion exchange resin to move the fixed ion strong exchange resin to the lower part of the tower. How to regenerate the tower. 4. After the completion of water sampling, only the upper chamber filled with the weak ion exchange resin having increased pressure loss due to trapping or consolidation of suspended solids is treated with raw water or treated water from immediately below the intermediate partition wall. The method of regenerating a countercurrent type ion exchange tower, comprising the steps of: (1) introducing low-pressure ion exchange resin, performing backwashing at a low flow rate to loosen the weak ion exchange resin, and then performing the regeneration method according to claim 1, 2 or 3.