JPH09117680A - Regeneration of rapid flow velocity back wash-type ion exchange tower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating a countercurrent ion exchange tower in a short time through a stable operation using a compact ion exchange tower. SOLUTION: In a method for regenerating a countercurrent ion exchange tower consisting of an upper and a lower water collecting device with an ion exchange resin 4 packed in a part above the lower water collecting device 3 and an inactive resin 7 with a specific gravity less than 1.0 packed in a part above the ion exchange resin 4 through a free board, for performing a descending water flow and an ascending chemical flow, the following steps (a)-(f) are sequentially put into practices: (a) a step to carry out a back wash at a high speed flow velocity from the lower water collecting device 3 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 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 in the ascending water current, (d) a step to perform a back wash step of (a) again, (e) a step to open a waste cleaning water valve and transfer the fixed layer to the lower part of the tower using the descending water current, and (f) a step to clean the resin by flowing water in the descending water current from the upper water collecting device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a countercurrent type ion exchange tower which uses downward flow water and upward flow chemicals using an ion exchange resin.

[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, rather than using a single bed of strongly acidic cation exchange resin (hereinafter referred to as strong cation resin) or strong basic anion exchange (hereinafter referred to as strong anion resin), depending on the raw water quality, The tower should be a multi-layered bed. When collecting water, pass weakly acidic cation exchange resin (hereinafter referred to as weak cation resin) → strong cation resin, and at the time of regeneration, strong cation resin → weak cation resin. This saves more regenerant than using a single resin. The multi-layer bed as used in the present invention is one in which a weak ion exchange resin is directly filled on a strong cation exchange resin without being partitioned by an intermediate partition wall.

The countercurrent type is divided into a type for performing descending circulating water and ascending circulating drug and a type for performing ascending circulating water and descending circulating drug. In either method, in order to exert the features of the countercurrent method, during the upflow process, that is, when the down-flowing water / up-flowing drug method is used, the up-flowing water / down-flowing drug method is used. Sometimes it is necessary to maintain the ion exchange resin in the fixed bed. In the upflow / downflow drug method, the fixed bed, that is, the ion exchange zone is disturbed due to the interruption of water flow, and the quality of the treated water is apt to deteriorate, and in addition to the discharge of suspended substances accumulated in the ion exchange resin during water flow, To make a freeboard for backwashing, special operations such as resin transfer process are required.
On the other hand, the descending circulating water / ascending circulating medicine method does not cause deterioration of water quality due to interruption of the flowing water, and therefore has an advantage that ON / OFF operation can be freely performed at the time of water sampling.

Further, in a multi-layer bed using a weak type ion exchange resin and a strong type ion exchange resin, the weak type ion exchange resin has a smaller specific gravity, and the inside of the resin tower is used in the upflow water / downflow regeneration system. The weak type and the strong type cannot be applied at the same time unless they are physically separated, whereas the descending flowing water / upflowing drug has 2
There is a feature that the layers can be separated. As shown in FIG. 3, when the intermediate water collecting pipe 20 is used to implement the descending circulating water and ascending circulating drug methods 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 the strong type progresses, and finally problems such as poor treated water quality and inability to collect water amount occur.

As a countermeasure against this, the following method has been proposed. 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 separation. As shown in FIG. 3, the regeneration is generally performed by arranging an intermediate water collecting pipe 20 on the upper part of the weak ion exchange resin 5 and introducing resin under the intermediate water collecting pipe from the upper part of the tower by opening a valve 18 to introduce pressurized water or pressurized air. Then, it becomes a fixed bed, and the medicine is passed in an upward flow. And
The regeneration waste liquid discharge valve 17 is opened to discharge the regeneration waste liquid.

(2) Ion-exchange resins tend to contract when they come into contact with regenerants, especially weak-type 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,
Even if the property of being difficult to be regenerated is taken into consideration, generally after the regeneration, particularly after the completion of the extrusion step, about 4 to 10% of the swelling tends to swell. However, since weak ion exchange resins are easily regenerated, the volume of the ion exchange resin after regeneration is about 20- The volume is reduced by 30%. On the other hand, at the time of water sampling, the weak ion exchange resin is converted from the regenerated type to the salt type, so that the volume thereof swells and the resin layer is likely 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, since the change in the ionic form of the weak type ion exchange resin is large and abruptly generated during the regeneration, voids are easily formed in the vicinity of the separation interface between the weak type and the strong type, and a part of the resin is formed. Becomes fluidized, and 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. To prevent fluidization due to contraction of the ion exchange resin and to achieve uniform dispersion of the regenerant,
By interrupting the drug in the middle of drug delivery, calming the contracted ion-exchange resin and then restarting the drug delivery several times, by delivering a low concentration regenerant at a low flow rate,
A method of reducing the influence of contraction, a method of increasing the amount of pressurized water introduced from above, or an amount of air has 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 a long regeneration time due to the complicated regeneration operation, an increase in the amount of waste liquid for regeneration, a complicated apparatus itself, and an increase in the regeneration cost.

(4) Ineffective resin 2 on the upper part of the intermediate water collecting pipe 20
No. 1 is backwashed as it is, and the resin under the intermediate water collecting pipe 20 is not backwashed during normal regeneration. However, if operation is continued in this state, accumulation of suspended solids and consolidation of resin particles occur. Therefore, [regeneration-water collection] is usually performed once every 7 to 20 times, so that the entire lower layer of the ion exchange resin is washed. 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, it is necessary to carry out backwash separation under the condition that most of the weak ion exchange resin is regenerated, and return to the initial condition where the 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) The intermediate water collecting pipe 20 may be damaged due to a repeated load due to a pressure loss when collecting water in the resin layer. Therefore, in the downward flow water / upflow flow system, using weak and strong ion-exchange resins in the same column does not achieve stable operation as the column diameter increases. It has become clear that it is difficult.

[0012]

DISCLOSURE OF THE INVENTION The present invention has improved the down-flowing water / up-flowing drug system, and has the above-mentioned problems, namely, a long regeneration time, an increase in the amount of regeneration waste liquid, and weak and strong ion exchange resins. Regeneration of countercurrent ion exchange tower that solves various problems at the time of mixing and passing, complicated apparatus and regeneration operation, etc., and can be regenerated in a short time using a compact ion exchange tower and can be operated stably. The challenge is to provide a method.

[0013]

In order to solve the above problems, according to the present invention, water collecting devices are provided above and below an ion exchange tower, and an upper part of a lower water collecting device is filled with an ion exchange resin, and an upper part thereof is further provided. 5-25% of ion exchange resin at the end of water sampling
The particle size is larger than that of the ion-exchange resin through the free board and the specific gravity is 1.0
In a method of regenerating a countercurrent ion exchange tower in which descending circulating water and ascending circulating medicine filled with smaller inert resin are used, the following steps (a) to (f) are sequentially performed to regenerate the resin. is there. (A), most of the ion-exchange resin is pressed against the inert resin by high-speed backwashing from the lower water collecting device provided at the lower part of the tower, and the suspended substances accumulated during water passage are passed through the inert resin to the tower. While discharging and removing from the upper water collecting device provided at the top,
A high flow rate backwashing process to form a fixed bed of ion exchange resin,
(B), a replenishment step in which the regenerant is passed upflow from the lower water collecting device at a flow rate required to maintain the fixed bed formed in step (a) at a lower speed than the high-flow rate backwash step; c), an extrusion step in which treated water is passed in an upward flow from the lower water collecting device at a flow rate that can maintain most of the fixed bed, and the remaining regenerant is effectively used, (d), and again (a) (E), opening the washing drain valve at the lower part of the tower from the upper water collecting device, or the air vent valve at the top of the tower and the washing drain valve at the lower part of the tower. And a resin moving step of moving the formed fixed layer to the lower part of the tower by using a downward flow of water, (f), a washing step of washing the resin by passing a downward flow of water from the upper water collecting device.

In the regenerating method, the regenerating treatment and the water collecting treatment are carried out at regular intervals, or at the time of water collecting, when the pressure loss increases, or the like, after the water collecting is completed, or after the extrusion step of (c) is completed. The step (a) and the settling step in which water flow is stopped and the resin is allowed to fall freely are repeated to promote separation of the accumulated suspended substance from the weak type and strong type ion exchange resins, and an inert resin layer. It is also possible to carry out the step of discharging and removing from the upper water collecting device via the. Since these steps are more effective as the freeboard ratio is higher, it is preferable to carry out these steps under the condition where the freeboard ratio is the highest. In the regeneration method, the inert resin has an effective diameter of 2 to 2 of the ion exchange resin.
Use 8 times the particle size, and the height of the inert resin layer is 100 ~
It is better to make it 400 mm, and the ion exchange resin is
Strong acidic cation exchange resin single bed, strong acidic cation exchange resin and weak acidic cation exchange resin multi-layer bed, strong basic anion exchange resin single bed, strong basic anion exchange resin and weak basic anion exchange resin double bed Either can be filled.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIGS. 1 and 2 showing an example of an ion exchange column to which the regeneration method of the present invention is applied,
The present invention will be described in detail. FIG. 1 is an example using a single strong ion exchange resin, and FIG. 2 is an example of a multi-layer bed using a strong ion exchange resin and a weak ion exchange resin. In the figure, water collecting devices 2 are provided above and below the ion exchange tower 1,
3 is provided, the strong ion exchange resin 4 or the strong ion exchange resin 4 and the weak ion exchange resin 5 are filled in the upper part of the lower water collecting device 2, and the ion exchange is further performed on it by some free board 6. An inert resin 7 having a larger particle size than the resins 4 and 5 and a size capable of holding the ion exchange resin and a specific gravity of less than 1.0 is filled in a range of 100 to 400 mm.

The upper and lower water collecting devices 2 and 3 are preferably a perforated plate type with nozzles, but may be a perforated tube type. Raw water inflow valve 8, reclaimed waste liquid discharge valve 9 in upper water collecting device 2, treated water outflow valve 10, backwash water inflow valve 1 in lower water collecting device 3.
1, a regenerant / extruded water inflow valve 12, a cleaning drainage valve 13, and an air vent valve 14 are connected to the top of the tower. Further, on the wall of the ion exchange tower, manual ball valves 15, 16 and 17 are provided so that the amount of ion exchange resin and the amount of inert resin can be adjusted. Sight glasses and manholes will be installed in appropriate places. The countercurrent type of the conventional type having an intermediate water collecting pipe usually needs to have a backwash freeboard of 75 to 100%. In the countercurrent type of full filling type, there is no freeboard, but in the conventional method such as the need to have a backwash tower separately, the apparatus configuration piping is complicated.

In the present invention, the structure inside the tower is typically as shown in FIG. Even if the freeboard 6 is much smaller than the conventional method and the inert resin layer 7 is added, the inside of the tower is effectively utilized and becomes compact. Further, an inert resin 7 having a specific gravity of 1.0 or less, which is 2 to 8 times the effective diameter of the ion-exchange resin, is further filled thereon to 100 to 400 mm. The freeboard 6 is important in the configuration of the present invention.
How much is In the case of the single resin shown in FIG. 1,
If this freeboard 6 is made smaller than the maximum swell, it will swell the most, that is, it will be regenerated 2-3 times, and the regenerated type will increase significantly, and the regenerated type resin will be used. When replacement and replenishment and filling are performed, as shown in Table 1, the salt type is changed to the regenerated type, and the volume of the resin is increased, which causes swelling pressure. Therefore, it is necessary to set the freeboard 6 shown in FIG. 1 to 2 to 10% of that of the regenerated type resin so that the swelling pressure of the resin will not be applied to the tower.

In this way, the volume of the resin after the completion of the actual one-cycle water sampling differs depending on the type of the load ions, the amount of water sampling, the type of the resin, etc.
The ratio of the freeboard to the recycled type of 10% is slightly increased due to the volume shrinkage after the completion of water collection, and is about 5 to 18% for the strong cation resin and about 15 to 25% for the weak anion resin. The ratio of the freeboard after the completion of water sampling is important for maintenance and management, and the resin level at the end of one cycle of water sampling is checked regularly to confirm that the freeboard 6 is properly maintained. This is very important. Also, after playback, at the normal playback level, and if necessary, 2
It is important to confirm the same when reproducing up to 2.5 times. The multi-layer bed using the strong ion exchange resin and the strong ion exchange resin shown in FIG. 2 shows more complicated resin volume swelling.

As shown in Table 1, the strong ion exchange resin is
At the time of water sampling, it shrinks from the regenerated form to the salt form, and contracts when regenerated. On the other hand, the weak ion exchange resin is completely reversed. The volume change of the weak cation resin is considerably different depending on the type of the resin and the type of loaded ions, but an example is as follows. <Example of ionic volume change> RH → R-Ca: +5 to + 15% RH → R-Na: +40 to + 55% The weak cation resin 5 has a hardness (Ca + Mg) of raw water of M−.
When the alkalinity is higher than the alkalinity, most of the ion forms at the end of water sampling are [R-Ca + R-Mg], and some of them are R-Na,
And a regenerated type (RH) is included.

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 NaHC corresponding to [M alkalinity-hardness]
Since O _{3 is} also ion-exchanged, a considerable amount of R-Na is also produced. In this case, R-Ca, R-Mg, and R-N depend on the ion composition of raw water and the amount of each ion loaded in one cycle.
a, the amount of unused RH produced is determined. On the other hand, the weak anion resin is generally used as raw water by using acidic soft water after the decarbonation tower.
1, mainly R-SO ₄ . However, in the R-HCO _{3 type,} there are some resins that exhibit a considerably large swelling ratio similar to the weak cationic resin. There is also a device for loading HCO ₃ ⁻ and CO ₂ without providing a decarbonation tower.

Therefore, when the strong type / weak type ion exchange resin shown in FIG. 2 is used, not only the ion type of the resin, the amount of loaded ions, the kind of the resin but also the filling ratio of the strong type 4 and the weak type 5 are used. The volume at the end of water sampling and the volume after regeneration are different. Therefore, even if the weak type 5 has many changes in swelling and contraction at the end of water collection and regeneration, it is preferable to reduce the influence of the swelling pressure on the tower by setting the filling amount to 60% or less of the total resin. . Then, the average volume (V ₁ ) after the completion of water collection for one cycle and the average volume (V ₂ ) after the regeneration are obtained.
Generally, the average volume (V ₂ ) after reproduction is smaller, so the proportion of freeboard should be determined as follows.

With reference to the average volume (generally indicating the swelling tendency) after the completion of water sampling for one cycle, the water quality fluctuation, that is, the load ion type at the end of water sampling, the production amount of each ion type, and the weak ion Considering the filling ratio of the exchange resin 5,
Determine the percentage of freeboard 6. Generally, 5-25% of the average volume after completion of water sampling may be set as the percentage of freeboard. The higher the ratio of the weak ion-exchange resin, the larger the ratio of the freeboard 6 is to improve the safety of the tower.
Also, it is essential to check the resin level at the end of one cycle of water sampling and periodically confirm that the free board 6 of 5 to 25% as described above is secured. And when swelling becomes large due to water quality fluctuations,
The strong type or weak type ion exchange resin is extracted from the valves 16 and 17 to maintain an appropriate ratio of the freeboard 6.

The material of the inert resin used in the present invention is, for example, polypropylene having a specific gravity of 1.0 or less, which has no residual regenerant, is easy to wash, and absorbs the swelling pressure of the ion exchange resin to some extent. Any elastic material and shape can be used. The particle size is usually such that the effective diameter of the ion exchange resin is 0.
Since it is about 65 mm, it may be about 2 to 8 times that. That is, the particle size of the inert resin is approximately 1.0 to
The diameter of 5.0 mmφ is preferably about 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 4 and 5 pass through the inert resin 7 when passing an upward flow, during extrusion, etc., preventing the water collecting port (slit) of the upper water collecting device 2 and making the set flow rate difficult to flow. .

The layer height of the inert resin 7 is 100-4.
Although it may be 00 mm, when the tower diameter is large, it should be set to a large value in consideration of whether or not the inert resin layer is uniformly flat. However, be aware that if the bed height is too large, it will be difficult to discharge suspended substances during high-flow backwashing. Since the inert resin 7 itself also causes clogging by crushing, the entire amount of the inert resin is discharged at every regular inspection, the inside of the tower is inspected and crushed, and the crushed inert resin is removed and refilled. It is also necessary to consider what to do. Using the tower structure based on the ratio of freeboards and its management as described above, the present invention performs the following regeneration process after the completion of water collection, and the ion exchange zone is disturbed even if the ratio of freeboards increases. Difficulty and easy to discharge the suspended substances trapped during water sampling.

(A) LV 20 to 26 m / h in the cation tower
As described above, high-velocity backwash of LV 14 to 20 m / h or more is performed in the anion tower for 2 to 3 minutes using the treated water in the upward flow from the lower water collecting device 3, and the strong or weak ion exchange resin 4 or 4 + 5 is used.
Is pressed against the inert resin 7 to form a fixed layer. The flow rate of the high-flow-rate backwash is slightly different depending on the specific gravity of the resin, the water temperature, and the ratio of the freeboard 6, but any flow rate that can form the fixed layer is essential. At this time, when collecting water
Part of the suspended solids accumulated in the strong cation resin 4 and mainly accumulated in the weak cation resin 5 in FIG. 2 are also discharged. (B) A flow velocity capable of maintaining the formed fixed bed, for example, LV6 to 8 m / h or more for the strong cation resin of the cation tower, and LV4 to 6 m / h for the strong anion resin of the anion tower.
2.5 to 4% of HC as a regenerant at flow rates above h
1, 1.5-4% NaOH (30-45 ° C.) is passed through.

(C) Next, the treated water is passed through at a flow rate capable of maintaining the fixed bed, and the extrusion step is performed. In the drug passing step and the extrusion step, the weak ion exchange resin has a smaller specific gravity than the strong ion exchange resin, and therefore the flow rate for maintaining the fixed bed may be the flow rate required for the strong ion exchange resin. Further, in the drug passing step and the extrusion step, the strong ion-exchange resin is converted from the salt form to the regenerated form, so that the resin swells. For this reason,
In the example of FIG. 1, it was feared that the resin pressure change due to the swelling would make it difficult to discharge the suspended substances trapped in the cation tower, but as a result of the experiment, the practical tower diameter was large, In case of 500φ or more, packed bed height L and tower diameter D
It was found that if the ratio L / D of 2 to 3 is less than or equal to 2 or 3, no consolidation due to swelling of the resin occurs at the end of the extrusion process.

This is probably due to the following reasons. In the present invention, since the flow-through step and the extrusion step are carried out at a low flow rate such that the fixed layer formed in the high-flow rate backwash step is carried out, the volume of the swollen portion of the strong ion-exchange resin, the strong type It is considered that the swelling pressure is released because the amount of increase of 4 to 5% in the cationic resin goes downward rather than in the lateral direction of the tower by the force of the resin dropping downward. The swelling volume of the strong cation resin is also 4 to 5% after regeneration as described above, which may be small.

For this reason, even in the cation tower of FIG. 1 which first comes into contact with the raw water, the suspended substance trapped is likely to move upward during the feeding and extrusion steps. In the case of a weak cation resin, the ionic form changes from a salt form to a regenerated form due to the upward flow flow-through process and extrusion process, so the volume usually shrinks by 20-25%, and it is consolidated during water sampling. The tendency of consolidation of the resin itself also disappears, the gap between the resins increases, and the suspended substances trapped gradually move upward. In the case of an anion tower, there is almost no mixing of suspended substances, but strong and weak anion resins have the same tendency, so
The consolidation is eliminated, and the crushed resin, etc. gradually moves upward.

(D) Subsequently, as in (a), a high flow rate backwashing step is carried out, and these suspended substances and the crushed and atomized resin pass through the inert resin layer all at once and are discharged from the upper water collecting device. Discharge to the outside of the system. Discharge of suspended substances and crushed fine resin by the steps (b), (c), and (d) is stronger and weaker than that of the strong cationic resin single layer of FIG. It is easier to use a multi-story floor using. This is for the following reason. That is, at the time of water sampling, the weak cation resin into which the raw water first flows is changed from the regenerated form to the salt form, so that it tends to swell, and it is easy to capture suspended substances in the raw water. 400 to 600 mm from the surface layer of resin
Suspended matter is difficult to enter only to some extent. Therefore,
This is because most of them are captured by the weak cation resin, and only a small amount of them enter the strong cation resin. As described above, the weak cation resin 5 has a large volume contraction from the salt form to the regenerated form, and the discharge of the suspended substance is further ensured by the high flow rate backwashing again after the injection process and the extrusion process. Is there.

(E) Next, from the upper water collecting device, the washing drain valve 13 at the bottom of the tower is opened, or the air vent valve 1 at the top of the tower.
4. The washing / drainage valve 13 is opened, and the resin moving step of moving the fixed bed formed by high-velocity backwashing to the lower part of the tower by using the descending flow of water is performed. This process is completed in about 0.5 to 2 minutes because the size of the freeboard is small, so it is preferable to slowly open the air vent valve 14 and the cleaning drain valve 13.
When the air vent valve 14 is opened, a full water process in the tower is required thereafter.

(F) As the final step, the raw water inflow valve 8,
The cleaning / drainage valve 13 is opened to perform normal cleaning, and the regeneration is completed at the specified water quality and time. In the present invention,
In particular, it is likely to occur in the cation tower, but a considerable amount of suspended matter and the like enters the resin layer, increasing the pressure loss during water collection,
The following methods have been adopted as countermeasures against non-uniform dispersion of regenerants during the drug passing / extrusion process. That is, in the case where the suspended solids penetrate deeper than the surface layer, and in the case of the strong cation resin 4 single layer in Fig. 1, the freeboard is the most under the condition that the volume of the salt-type resin after the completion of water sampling is the smallest. High-velocity backwash with raw water or treated water under increased conditions for 2-3 minutes, then stop the flow of water to the formed fixed bed, and let the resin settle freely to suspend the resin and suspended solids. The suspended substance is discharged by repeating the settling process for 5 to 15 minutes to accelerate the separation of the suspended solids.

In the case of the multi-layer bed shown in FIG. 2, it may be either before or after the regeneration, but it is preferable to use the treated water after the regeneration so that the total volume of the resin becomes small. This is because the volume of the weak ion exchange resin is the smallest in the regenerated type. That is, the normal regeneration level of the medicine is passed, and after the extrusion, a setting step for 2 to 10 minutes is performed,
Repeat the high flow rate backwash for 2-3 minutes in a normal cation tower.
Only about once. Anion towers do not need to be run as frequently as cation towers, as suspended solids are usually rarely mixed. After this operation, normal treated water is regenerated again so that the total regeneration level is 2 to 2.5 times, so that stable treated water can be obtained. By repeating the high-flow-rate backwashing step and the sedimentation step as described above, the present invention can implement countermeasures against abnormalities.

[0033]

The present invention will be described below in more detail with reference to examples. Example 1 RH of HCR-W2 as a strong cation resin was used in a large chamber of an ion exchange column having an inner diameter of 1300φ × 3200H (body length).
It was filled so as to have a layer height of 2780 mm. Top and bottom water collecting device: Perforated plate method with nozzle Freeboard: 220mm (6.8%) against regenerated type, 370-390mm (14.2 to 15.0%) after water sampling, inert resin : Polypropylene 2.5-3.5 mmφ, reproduction level: 29.5 g / liter-R (strong type cationic resin R-Na), 100% HCl,

Raw water: River water Coagulated filtered water Treatment concentration: 0.5 degrees or less Table 2 shows the ionic composition of raw water.

[Table 2]

Table 3 shows the regeneration conditions in the regeneration step (cation tower).

[Table 3] Note) Resin transfer process: The air vent valve was opened.

[Results] 1) Water sampling time: 19.1 hours, water sampling 30 m ³ / h, 2) Water sampling amount: 572.5 m ³ / c Anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 75% 4) Treated water quality: 0.2 to 5.0 μS / cm 5) Regeneration time: about 78 minutes 6) No increase in pressure loss was observed even at the 10th cycle.

Example 2 Dowex 650C was used as a strong cation resin in an ion exchange column having an inner diameter of 1200φ × 2500H (body length) and RH.
The shape was 1200 mm, and the weak cationic resin, Levatit CNP80, was filled in the shape R-H for 750 mm, and the raw water in Table 2 was passed through. Upper and lower water collecting device: Perforated plate method with nozzle Freeboard: 350mm Weak type cationic resin regenerated type 1350mm Strong type cationic resin regenerated type 750mm Freeboard at this time% 16.7% Layer height weak after one cycle of water sampling Cationic resin 810mm Strong type cationic resin 1310mm Freeboard at this time% 16.5% Regenerator amount: 100% HCl 85kg Inert resin: polypropylene 2.5-3.5mmφ, 200mm

Table 4 shows the regeneration conditions in the regeneration step.

[Table 4]

[Results] 1) Water sampling time: 19 hours, water sampling 30 m ³ / h, 2) Water sampling amount: 570 m ³ / c Anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 88.1% 4) Treated water quality: 0.2 to 5.0 μS / cm 5) Regeneration time: about 80 minutes 6) No increase in pressure loss was observed even at the 10th cycle.

Example 3 Using the ion exchange column 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 terms of turbidity. Regeneration was carried out in the same manner as in Example 2. In addition, every 10 cycles, the treated water is used before the hydrochloric acid injection, the high flow rate backwash step is stopped for 2 minutes and the water flow is stopped, and the sedimentation step in which the resin is allowed to fall freely is repeated 5 minutes twice. Special reproduction was performed. The amount of regenerant for special regeneration was the same as in normal times.

[Results] 1) Water sampling time: 18.8 hours, water sampling 30 m ³ / h, 2) Water sampling: 565 m ³ Anion tower outlet end point: 5 μS / cm 3) Regeneration efficiency: 87.3% 4) Treated water quality: 0.2 to 5.0 μS / cm 5) Regeneration time: Approximately 80 minutes during normal regeneration, approximately 105 minutes during special regeneration 6) No increase in pressure loss was observed even when the cycle proceeded.

[0042]

EFFECTS OF THE INVENTION According to the present invention, the disadvantages of the conventional countercurrent type ion exchange tower for performing descending flow water / upflow drug, namely, extension of regeneration time, increase of the amount of regeneration waste liquid, and problems associated with backwashing It is possible to solve problems such as generation, mixing of strong and weak resins, complication of equipment and recycling operation, and increase of recycling cost. As a result, a simple and compact ion exchange apparatus and a simple and short-term regeneration method can be provided, and good treated water quality can be obtained inexpensively and stably.

[Brief description of the drawings]

FIG. 1 is a schematic view of a single layer ion exchange tower of a strong ion exchange resin used in the regeneration method of the present invention.

FIG. 2 is a schematic view of an ion exchange column having a double bed of strong and weak ion exchange resins used in the regeneration method of the present invention.

FIG. 3 is a schematic view of a conventional ion exchange tower using an intermediate water collection system.

[Explanation of symbols]

1: Ion exchange tower, 2: Upper water collector, 3: Lower water collector, 4: Strong ion exchange resin, 5: Weak ion exchange resin, 6: Free board, 7: Inert resin, 8: Raw water Inflow valve, 9: regeneration drainage outflow valve, 10: treated water outflow valve, 11:
Backwash water inflow valve, 12: Regeneration agent and extruded water inflow valve, 13: Wash drainage valve, 14: Air vent valve, 15: Inert resin amount adjustment valve, 16: Strong ion exchange resin amount adjustment valve, 17: Weak Type ion exchange resin amount adjusting valve, 18: pressurized water or pressurized air introduction valve, 19: upper backwash water valve, 20: intermediate water collecting device, 21:
Backwash drain valve, 22: ineffective resin,

Claims (4)

[Claims] 1. Water collecting devices are provided above and below the ion exchange tower,
The upper part of the lower water collecting device is filled with an ion exchange resin, and the upper part thereof has a particle size larger than that of the ion exchange resin through a free board of 5 to 25% of the ion exchange resin at the end of water sampling.
In a method for regenerating a countercurrent type ion exchange column, which is a size capable of holding an ion exchange resin and is filled with an inert resin having a specific gravity of less than 1.0, downward flow water / upflow flow chemical is used. The method for regenerating a countercurrent ion exchange tower is characterized in that the steps are sequentially performed to regenerate the resin. (A), most of the ion-exchange resin is pressed against the inert resin by high-speed backwashing from the lower water collecting device provided at the lower part of the tower, and the suspended substances accumulated during water passage are passed through the inert resin to the tower. While discharging and removing from the upper water collecting device provided at the top,
A high flow rate backwashing process to form a fixed bed of ion exchange resin,
(B), a replenishment step in which the regenerant is passed upflow from the lower water collecting device at a flow rate required to maintain the fixed bed formed in step (a) at a lower speed than the high-flow rate backwash step; c), an extrusion step in which treated water is passed in an upward flow from the lower water collecting device at a flow rate that can maintain most of the fixed bed, and the remaining regenerant is effectively used, (d), and again (a) (E), opening the washing drain valve at the lower part of the tower from the upper water collecting device, or the air vent valve at the top of the tower and the washing drain valve at the lower part of the tower. And a resin moving step of moving the formed fixed layer to the lower part of the tower by using a downward flow of water, (f), a washing step of washing the resin by passing a downward flow of water from the upper water collecting device. 2. The resin is freed by stopping the flow of water in step (a) after the completion of water collection or after the completion of the extrusion step of (c) at regular intervals of the regeneration processing and water collection processing. The countercurrent ion exchange according to claim 1, wherein the step of discharging the accumulated suspended solids from the upper water collecting device through the inert resin layer is repeated by repeating the settling step of dropping to the upper side. How to regenerate the tower. 3. The inert resin having a particle diameter of 2 to 8 times the effective diameter of the ion exchange resin is used, and the height of the inert resin layer is 100 to 400 mm. 2. The method for regenerating a countercurrent ion exchange tower according to 2. 4. The ion exchange resin is a single bed of strongly acidic cation exchange resin, a multi-layered bed of strongly acidic cation exchange resin and weakly acidic cation exchange resin, a single bed of strongly basic anion exchange resin,
The method for regenerating a countercurrent type ion exchange column according to claim 1, 2 or 3, characterized in that it is packed with either a multi-layer bed of a strongly basic anion exchange resin or a weakly basic anion exchange resin.