JPH11104639A - Reverse osmosis membrane type pure water-making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply high purity water by driving an RO supply pump by an ejection amt. variable apparatus and operating the delivery amt. variable apparatus corresponding to the consumption amt. of purified water to operate the same in water making amts. of two or more stages. SOLUTION: The rotational speed of an RO supply pump 5 is controlled in a multistage fasion by the control signal from a liquid level meter 13 or the like not only to reduce the stop frequency of the RO supply pump 5 to a large extent but also to enhance the durability of an RO module 6 and the quality of pure water is enhanced and stabilized. Concretely, when the liquid level in a tank lowers to reach a lower LC, the signal from a liquid level meter 113 transmits the high speed rotation signal of the RO supply pump 5 to an inverter 121 through a signal line 120. The RO supply pump 5 rotates in proportion to the frequency formed by the inverter 121. Generally, it is pref. to set Q1 >Q0 >Q2 with respect to the flow rate Q0 of pure water steadily consumed at the use point and, in this case, the RO supply pump 5 is almost continuously operated so that the number of rotations thereof is set to the rotational speeds corresponding to Q1 and Q2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane type pure water production apparatus for producing highly purified pure water used for washing, blending and dilution in the medical field such as dialysis. In particular, it is an object of the present invention to provide an apparatus for producing pure water for dialysis which is free from bacteria and endotoxin contamination.

[0002]

2. Description of the Related Art FIG. 4 is an example of a flow chart of a conventional reverse osmosis membrane type pure water producing apparatus for dialysis.

[0003] In FIG. 4, raw water such as tap water is pressurized by a raw water pump (1), and is softened (2), activated carbon filter (3),
Water is passed in the order of the filter (4). The pretreatment section (A) is formed by these (1) to (4) to remove suspended substances, residual chlorine and the like in the raw water. The pretreatment water is boosted to a predetermined high pressure by the RO supply pump (5) and supplied to the RO module (6).
The RO module (6) is composed of a spiral or hollow fiber reverse osmosis (RO) membrane element part and a casing for accommodating the element part, and the space between the two is hermetically sealed by means such as an O-ring. I have.

[0004] A part of the pretreated water passing through the surface of the reverse osmosis membrane becomes purified water that has been permeated through the reverse osmosis membrane and becomes purified water.
Reach 4). On the other hand, the concentrated water in which impurities such as salt are concentrated is discharged out of the system via the pressure control valve (18). This RO
The part with the module (6) at the core is the water purification part (B). High purity pure water from which inorganic ions, organic matter and fine particles including bacteria have been removed from the pretreated water by the reverse osmosis membrane is RO RO
It is stored in the water tank (7).

[0005] (8) is an ultraviolet sterilizer, RO water tank (7)
Irradiates the pure water stored in the container with ultraviolet rays to prevent bacteria from being generated during the storage. From the RO water tank (7), pure water is supplied through a supply pump (9) and a supply line (10) to a central dialysate preparation device and a dialysis device (end point of use) (11) connected to a patient. Is done.

On the other hand, the pure water in the RO water tank (7) is constantly circulated through a pure water circulation line (12). This is because if the consumption of pure water at the point of use disappears, the pure water in the tanks and pipes will stay for a long time, bacteria will proliferate, and a small amount of ionic components will be eluted from the pipes, degrading the water quality. This is to prevent it.

[0007] The flow rate of pure water from the RO water tank (7) is (11)
Thereafter, the liquid level varies depending on the number of patients to be subjected to the dialysis treatment. Therefore, the liquid level is detected by the liquid level gauge (13) of the RO water tank (7), and the operation of the RO supply pump (5) is controlled. That is, the signal from the level gauge (13) is transmitted to the pump control signal line (20).
Arrives at the RO supply pump (5) due to the
In C), the RO supply pump (5) is started to start fresh water generation, and the RO supply pump (5) is stopped in the upper setting (HC) to interrupt fresh water generation.

In the water purification section (B), the RO module (6)
Operating the flow control valve (16) of the RO supply pump (5) while watching the permeated water flow meter (14) and the concentrated water flow meter (15), to operate the pressure gauge (17). )
Operate (18). A part of the concentrate is pump-circulated through a concentrate circulation line (19) in order to obtain a predetermined flow rate in the RO module (6).

[0009] As is well known, in dialysis treatment, blood and a dialysate (prepared by mixing the above pure water with a stock solution containing a predetermined electrolyte component) are brought into contact with each other through a dialysis membrane in a dialyzer. The difference in substance concentration removes waste products in the blood of the dialysis patient, and replenishes the blood side with necessary ionic electrolytes and the like from the dialysate. Therefore, naturally, the dialysate is required to have high cleanliness.

[0010] Further, with the development of dialysis treatment technology, a higher level of cleanliness has been required. In other words, a uretoxin component having a higher molecular weight than the components removed by conventional dialysis therapy was found, and it was necessary to remove such a larger substance in order to improve the long-term patient condition. I've been. To this end, it is necessary to increase the pore size (pore size) of the dialysis membrane. This means
Conversely, it suggests that there is a high risk that impurities such as fine particles in the dialysate, which have been conventionally blocked by the dialysis membrane, are mixed into the blood side. Furthermore, a therapy called on-line hemodiafiltration, which actively removes plasma components in blood and injects a dialysate in an amount equivalent to that, into a patient has also begun to spread.

As is apparent from the above, the water used in these dialysis treatments has been required to have higher cleanliness (cleanness) than ever before, and new technical problems have begun to arise. That is, not only the bacteria during dialysis but also the endotoxin component peeled off from the outer membrane of the cell wall after the gram-negative bacteria, which is a kind of bacteria, have been killed. Endotoxins are also symptomatically called pyrogens,
A toxin component that causes fever in patients. This is a so-called O
It is a very difficult substance to handle, such as the bellow toxin at -157, generated by the killing of bacteria. As a short-term problem when a large amount of endotoxin is mixed into blood, the patient suffers from undesired symptoms such as a decrease in blood pressure and fever.

[0012] More recently, chronic damage has been pointed out due to finer fragments of this endotoxin. For dialysis patients who have to receive 10 to 15 hours of treatment each week for their lifetime, avoid them if they are not manifested in short-term treatment, but in view of chronic disease in long-term treatment for more than 10 years. It is a serious problem that cannot be passed. This fragment has a minimum molecular weight of 5,000 daltons, which is comparable to or even smaller than the size (molecular weight) of the uretoxin component to be removed from the patient. For example, dialysis membranes that are permeable to 50,000 dalton uremic toxin components are currently used. Therefore, in order to carry out such a high-performance dialysis treatment more safely, the amount of endotoxin in the dialysate must be minimized.

On the other hand, Gram-negative bacteria that release this endotoxin are not special bacteria but are resident bacteria that live in a general living environment, and easily grow in pure water or dialysate.
Therefore, even if endotoxin is completely removed, if gram-negative bacteria are mixed in, it will grow rapidly and generate new endotoxin. In this way, the problem derived from bacteria is different from general inorganic and organic impurities, and increases more than the amount mixed in.In addition, if the sterilization process is wrong, even if the bacteria themselves can be sterilized, it will have the opposite effect. is there.

[0014] These problems have been extremely difficult to solve with the conventional apparatus in consideration of the following situation in which a pure water apparatus for dialysis is placed.

(1) If chlorine remains in the dialysate, the blood of the patient is damaged (red blood cells are destroyed). Therefore, the residual chlorine added to the raw water to suppress bacterial generation is completely removed by the activated carbon filter (3) in the pretreatment section (A). Therefore, the whole system is vulnerable to bacterial contamination. On the other hand, the environment of a hospital facility is not necessarily bacterially favorable, and there is a possibility that bacteria may enter the atmosphere or from an operator.

(2) Unlike the electronics industry, the scale is small, and it is difficult to have a dedicated engineer to control the sterility of purified water.

(3) The pure water apparatus is stopped at night. Further, as described above, the intermittent fresh water generation operation is performed according to the consumption at the use point during the treatment. In addition, due to the complexity of the system, dead space is easily generated in the piping. Bacteria are easily proliferated in places where such water stays and in time zones.

(4) RO module is about 10 kg / cm ²
Although it is operated at about the same pressure, pressure shock is applied to the reverse osmosis membrane as the RO feed pump (5) is turned on and off, and the membrane is stretched.If this is repeated for a long time, cracks occur on the membrane surface,
Pretreatment water with bacterial contamination may leak. RO
Increasing the capacity of the water tank (7) can reduce the frequency of starting and stopping the RO supply pump (5), but conversely increases the pure water residence time in the tank, which is not preferable from the viewpoint of preventing bacterial generation.

(5) At the same time, there is a possibility that a large amount of bacteria and endotoxin produced in the dead zone are temporarily discharged due to a shock when a high pressure is suddenly applied. .

(6) Since the reverse osmosis membrane of the RO module has low chlorine resistance, it is difficult to routinely perform simple chlorine sterilization as a sterilization operation. Therefore, it is not rare that the sterilization treatment is not performed for a long period of time, and the bacteria easily grow.

(7) Similarly, since the reverse osmosis membrane cannot tolerate chlorine, the water supplied to the reverse osmosis membrane is subjected to a treatment for removing chlorine from raw water by an activated carbon filter (3). Therefore, the activated carbon filter is in a chlorine-free state, easily becoming a breeding ground for bacteria, and associated with it, there is a high risk of generating endotoxin. Therefore, if there is a slight defect in the reverse osmosis membrane, this is the secondary side (pure water side)
To leak. Even if there is no abnormality in the reverse osmosis membrane, if there is a deterioration in the function over time such as an O-ring that fluidly seals the element and the casing, contamination may occur due to a sudden pressure shock when the RO pump is turned on and off. The leaked primary raw water leaks.

(8) Endotoxin is a so-called dead body of bacteria. Therefore, if bacterial outbreaks are observed, unless proper sterilization is performed, gram-negative bacteria will be killed, but rather, a high concentration of endotoxin will be dispersed.

[0023]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional apparatus and provides a reverse osmosis membrane-type pure water producing apparatus capable of supplying a stable and highly pure water that meets the needs of the medical community. It is in. It is still another object of the present invention to provide a reverse osmosis membrane type pure water producing apparatus which is more operable and economical than the conventional apparatus.

[0024]

As a result of intensive studies by the present inventors, the above object of the present invention has been industrially advantageously achieved by the present invention having the following constitution.

That is, the constitution is defined as “a pretreatment unit for removing residual chlorine in raw water, and a water for purifying raw water treated in the pretreatment unit by an RO module having a RO supply pump and a reverse osmosis membrane. A purification unit, and an RO water tank unit for storing purified water obtained in the water purification unit.
A reverse osmosis membrane type pure water production apparatus wherein the O supply pump is driven by a variable discharge amount device, the variable discharge amount device is operated in accordance with the consumption of purified water, and the operation is performed at two or more levels of fresh water. ".

The most important feature of the present invention is that the RO supply pump is driven by the variable discharge amount device, and the variable discharge amount device is operated in accordance with the consumption of purified water. There is a point.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the rotation speed of an RO supply pump (5) is controlled in multiple stages by a control signal from a liquid level gauge (13) or the like, and the stop frequency of the RO pump (5) is greatly increased. And improve the durability of the RO module (6),
Improve and stabilize purified water. [First Embodiment] The first embodiment of the present invention will be described below with reference to the flowchart of FIG. (1) to (12), (14) (1
5) and (17) to (19) are the same components as those in FIG.
The flow control valve (16) shown in FIG. 4 is omitted. (11
Reference numeral 3) denotes a liquid level gauge, which has detection signals at three points of a middle stage (MC) in addition to an upper stage (HC) and a lower stage (LC). The detection signal of the liquid level gauge (113) reaches the inverter (121) via the pump control signal line (120), and adjusts the rotation speed of the RO pump (5).

Hereinafter, the operation will be described in detail with reference to the drawings. Now, the RO water tank (7) stores pure water produced in the pretreatment section (A) and the water purification section (B), and its liquid level is H.
In any position between C and LC, the RO pump (5) is stopped. With the consumption of pure water at the use point (11), when the liquid level in the tank drops and reaches the lower LC, the signal from the liquid level gauge (113) is sent to the inverter via the signal line (120).
A high-speed rotation signal of the RO supply pump (5) is transmitted to (121).
Thus began the manufacture of pure water at a predetermined water production rate Q _1, the liquid level in the tank begins to rise (recovery). This is the middle MC
The desalination rate upon reaching decreased to Q _2, to continue the desalination. When the liquid level further rises and reaches the upper stage HC, the RO pump (5) is stopped.

The inverter (121) used here is not special, and it is sufficient that an arbitrary frequency can be generated from a commercial power supply (50/60 Hz). The RO pump supply (5) rotates in proportion to this frequency. The purified water switching valve (122) is a three-way valve, and the purified water immediately after the start of the operation of the RO supply pump (5) may include impurities generated at the stagnation portion of the pipe. Therefore, the generated water is discharged from the drainage line (123) to the outside of the system for several minutes after the start of operation.

Generally, it is preferable to set Q ₁ > Q ₀ > Q ₂ with respect to the pure water flow rate Q ₀ constantly consumed at the use point. In this case, RO feed pump (5)
Rotational speed is switched at a rotational speed corresponding to Q _1, Q _2, is operated almost continuously.

The characteristics of the reverse osmosis membrane generally have a pressure dependency as shown in FIG. Therefore, by reducing the rotation speed of the RO supply pump (5), the pressure applied to the reverse osmosis membrane changes, and the flow rate of fresh water in the RO module also decreases substantially in proportion to the pressure. On the other hand, as the pressure decreases, the conductivity of the produced pure water also deteriorates. For example, if the operating pressure is K point 10
What was operated at kg / cm ² was 5kg / c at point L
When it is reduced to m ² , as shown in the following figure (E), the fresh water flow rate becomes almost half. On the other hand, as shown in FIG.
The NaCl exclusion rate, which is a representative of monovalent ions, decreased from 99.1% to 98.7% at the K 'point (the transmittance increased from 0.9% to 1.3%, and the transmission rate exceeded 40%) Amount rises)
Then, the quality of the purified pure water changes. Therefore, the conventional pure water apparatus for dialysis was operated under a constant pressure condition.

The operation under the constant conditions is such that the specific resistance is 16 MΩ · cm or more (conductivity of 0.0
(Less than 63 μS / cm) due to the operational know-how in the electronics industry which requires almost theoretical pure water. In this field, water quality fluctuations are not acceptable because water quality stability is a top priority. Therefore, the operation is always performed under a constant condition, and when the consumption amount fluctuates at the use point, the pure water is often overflown and drained.

However, in a pure water producing apparatus for dialysis medical treatment, such a change in electric conductivity is essentially no problem. The reason is that in a general RO device for dialysis, tap water having an electric conductivity of 300 μS / cm level is
(6) Purify to 3 μS / cm level (exclusion rate: 99%). However, at the point of use of a dialysis device or the like downstream of the RO water tank (7), a large amount of an electrolyte component (such as NaCl) is injected into the pure water to adjust the dialysate to have the same level of conductivity as blood. I do. Therefore, it is finally adjusted to 14 mS / cm (= 14,000 μS / cm). Therefore, due to a decrease in the operating pressure due to a decrease in the amount of fresh water in the RO module, a small amount of NaCl permeates into pure water and
Even when μS / cm (percentage of permeate is increased by more than 30%), the final dialysate has a fluctuation of less than percent, and there is no problem in terms of the dispersion of the electric conductivity of the patient and the accuracy of the electrolyte preparation. is there.

The role of water purification in the RO device for dialysis is as follows:
In order to reliably and stably remove heavy metal ions such as aluminum ions, bacteria and endotoxin, such a change in the removal performance of monovalent salts which are added in large amounts at the point of use does not pose a problem. The monovalent salt is measured because the conductivity measurement method is simple and the apparatus is inexpensive. Therefore, the performance of the reverse osmosis membrane is deteriorated (for example, leakage of water on the primary side due to breakage of the reverse osmosis membrane). )) Is used as an index for abnormality management of the occurrence of That is, a decrease in the electrical conductivity based on the result of the occurrence of the leak in the film is managed, and all the factors of the decrease in the electrical conductivity are not film leaks. As long as the reverse osmosis membrane is normal, a slight change in the permeation amount of monovalent ions (accordingly, conductivity) due to a change in the controlled pressure condition or flowing water condition is not a problem in the RO device for dialysis.

As described above, according to the apparatus of the present invention, in part, the RO supply pump (5) is variably controlled by an inverter, thereby minimizing the stoppage of the apparatus which triggers bacterial growth and endotoxin generation. However, it has a few more excellent characteristics.

Secondly, a reverse osmosis membrane generally using a synthetic membrane has a thickness of about 200 μm as a whole, but the dechlorination functional layer involved in pure water production has only one layer.
It is about 0.2 μm on the surface of 1 / 000th, and this is applied on the lower supporting layer or substrate. Therefore, each time frequent pressure is repeatedly applied, the dechlorination functional layer expands / contracts, causing wrinkles on the surface and cracks at the portion, and peeling at the interface with the lower supporting layer. There are concerns. If such cracks occur, they can lead to leakage of the contaminated raw water on the primary side to the secondary side.

The third is not directly related to the degree of cleanliness of purified water, but is advantageous to facilities utilizing the same. The conventional device was operated by the flow control valve (16) in FIG. Therefore, the RO supply pump (5) was operated at a higher pressure including the pressure loss at the flow rate control valve (16), for example, about 15 kg / cm ² . Therefore, the rotational speed of the RO supply pump increases, and the noise of the RO supply pump (5) itself increases. Further, the metallic cavitation noise accompanying the rapid depressurization of the flow control valve (16) is noisy, and there are cases where complaints are received not only from the operator of the apparatus but also from patients who are undergoing treatment in a hospital room. The present invention solves these problems and operates with the minimum required energy, so that the power consumption can be significantly reduced.

[0038] Dialysis treatment is generally not performed at night. In particular, there is no demand for fresh water for more than 32 hours in a row, from midnight on Saturday to early morning on Monday. Therefore, the discharge valve (1
30), if there is no demand for fresh water for more than one hour,
That is, when there is no operation request of the RO supply pump (5),
The discharge valve (130) is opened only for about several minutes, and the water retained in the activated carbon filter (3) is discharged out of the system. Further, prior to the start of the operation of the apparatus, the discharge valve (130) is temporarily opened to suppress supply of raw water contaminated with bacteria and the like to the RO module. In addition, for example, when the operation is stopped continuously for 4 to 8 hours, the RO supply pump (5) is also operated for about ten and several minutes to receive fresh raw water and expel remaining water of the entire system.
As a result, the influence of bacterial growth occurring during the stay is reduced. [Second Embodiment] A second embodiment in which the apparatus is not stopped at all will be described with reference to FIG.

In FIG. 3, (1) to (15), (17) to (19)
Are the same as the components with the same numbers in FIG. A new raw water tank (224) is provided, and tap water is temporarily stored in this raw water tank.
Stored at (225). The liquid level gauge (13) has two points as in FIG. Accordingly, pure water is supplied into the RO water tank (7) at the lower limit LC, but when the upper limit HC is reached, the purified water switching valve (222) is switched to the line (223), and the purified water is supplied to the raw water tank.
While returning to (224), the concentrated water switching valve (225) is switched to the line (226), and the same is returned to the raw water tank (224).
At this time, in order to reduce the life and power consumption of each component, the signal is transmitted to the inverter (221) via the signal line (220),
Reduce the rotation speed of the RO pump (5). Therefore, the water is once separated into purified water and concentrated water by the RO module (6), but is associated with the raw water tank (224) and is recycled.

When the liquid level gauge (13) reaches LC again, the RO supply pump (5) is rotated at a high speed by the inverter (221).
At the same time, the switching valve (222) and the switching valve (225) are switched, the purified water is received into the RO water tank (7), and the flow meter (1
The concentrated water passed through 5) is drained out of the system. Switching valve
(222) may be switched several minutes later. This allows the whole system to be accepted as pure water after being stabilized under high-speed conditions, and the quality of purified water is more stable. This switching valve (222)
Operates in the same manner as the switching valve (122) of the first embodiment (FIG. 2), but unlike the first embodiment, the transient pure water during this period is stored in the raw water tank (224). To return, tap water can be used effectively.

As can be seen from the above, the gist of the present invention is that it is common practice to operate under a certain condition in the past. Is made possible. Therefore, the present invention is not limited to the above-described embodiment, and the following applications are possible, and these are also included in the present invention.

For example, the liquid level gauge (13) of the first embodiment
Although it is point detection, more multipoint detection may be used.
Also continuously detects the liquid level and multi-stage RO supply pump
The rotation speed of (5) may be controlled. Furthermore, a signal of the required flow rate and a signal of the number of patients being treated are obtained from the dialysis machine (11),
The rotation speed of the RO supply pump (5) may be controlled continuously. As described above, the change in water quality due to this change in rotation speed is acceptable in the field of dialysis medicine, but the ratio between the high-speed rotation speed and the low-speed rotation speed of the RO supply pump (5) is 3: 1. , Preferably about 2: 1.

When the RO supply pump (5) is operated or its speed is changed, if the speed is slow-started / slow-down by utilizing the characteristics of the inverter, a sudden pressure shock can be alleviated more and the durability of the reverse osmosis membrane can be further reduced. It is effective in improving the performance.

Further, in the reverse osmosis membrane, the amount of fresh water and the NaCl rejection change depending on the temperature of the supplied water. Thus the rotational speed of the pressure therefore RO feed pump for obtaining a purified water flow rate of Q ₁ and Q ₂ in the first embodiment (5) is to be set from the outside, it may be changed in summer and winter. The number of patients treated at hospitals varies depending on the day of the week and time of day. Therefore, the rotation speed corresponding to the standard flow rate QS may be inputted from the outside, and the rotation speed may be switched to two rotation speeds having widths above and below the value.

In the second embodiment, the inlet or the circulation line of the RO module (6) or the raw water tank (224) is
A V-sterilizing light can be provided. Thereby, the bacteria in the raw water supplied to the RO module (6) can be minimized. In the figure, the raw water tank (224) is a water softener (2) and an activated carbon filter.
Although it is on the upstream side of (3), this can be the downstream side. In this case, since the circulating water of the lines (223) and (226) does not pass through the activated carbon filter (3), a sterilizing agent such as formalin is supplied to the raw water tank (224) when there is no demand for pure water. It can be added and used as a cleaning chemical tank, and can be used for sterilization and cleaning of the RO module (6).

[0046]

The endotoxin content in raw water is 10,000
Conventionally, the RO apparatus for dialysis has a level of 50 IU / ml, whereas the level of 0 IU / ml, and sometimes 200 IU / ml.
/ Ml in purified pure water, which can sometimes reach to 1 ml / ml, for a long period of time by the apparatus shown in the first and second embodiments without complicated operations such as sterilization operation. It became possible to maintain it at 5 IU / ml or less.

This has been, but not limited to, significant results to ensure the therapeutic safety of dialysis patients. As described above, various new therapies currently being studied necessarily involve a clean dialysate, which is useful for putting these high-performance therapies into practical use.

Further, for the facility side, it is possible to save energy (reduce the consumption of electric power and water) and to improve the durability of the expensive RO module, which has great economic effects. In addition, the environment of the hospital room can be improved by reducing noise.

[Brief description of the drawings]

FIG. 1 is a flowchart of a first embodiment according to the present invention.

FIG. 2 is a diagram illustrating the performance of a reverse osmosis membrane.

FIG. 3: Flow of a second embodiment according to the present invention.

FIG. 4 is a flow of a conventional apparatus.

[Explanation of symbols]

 1: Raw water pump 2: Water softener 3: Activated carbon filter 4: Filter 5: RO supply pump 6: RO module 7: RO water tank 13: Liquid level gauge 113: Liquid level gauge 120: Pump control signal line 121: Inverter 220 ： Pump control signal line 221 ： Inverter

Claims (1)

[Claims] 1. A pretreatment section for removing residual chlorine in raw water,
A water purification unit for purifying raw water treated in the pretreatment unit by an RO module incorporating a RO supply pump and a reverse osmosis membrane, and an RO water tank unit for storing purified water obtained in the water purification unit; A reverse osmosis membrane type pure water production apparatus in which the RO supply pump is driven by a variable discharge amount device, the variable discharge amount device is operated in accordance with the consumption of purified water, and the operation is performed at two or more stages of fresh water production. .