JP2007136413A - Water cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water cleaning device which can improve a system recovery rate by circulating concentrate through a system without directly discharging it, and easily set/control the system recovery rate. <P>SOLUTION: In the water cleaning device for introducing raw water to be cleaned, supplied from a feed water tank, into a reverse osmosis membrane module to subject the raw water to membrane separation treatment, and supplying permeate to the outside of the system as cleaned water, concentrate separated from the cleaned water by the reverse osmosis membrane module is returned to the feed water tank. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a water purification apparatus using a reverse osmosis membrane. More specifically, the system recovery rate is improved by circulating the system without draining the concentrated water as it is, and the system recovery rate can be easily achieved. The present invention relates to a water purifier that can be set and managed.

  Conventionally, a water purifier using a reverse osmosis membrane has been provided in order to remove impurities and microorganisms contained in drinking water such as tap water and groundwater and obtain clean water.

  In such a general reverse osmosis membrane, the ratio of purified water permeating from raw water (hereinafter referred to as “membrane recovery rate”) is 8 to 20% as an average value. This value is set and recommended by the membrane manufacturer when the membrane recovery rate is higher than the reverse osmosis membrane structure. If the membrane recovery rate is less than this, it is said that pure water can be efficiently permeated without damaging the reverse osmosis membrane.

  However, if the membrane recovery rate recommended by the above manufacturer is strictly observed in the conventional water purifiers, about 80% of the raw water is drained as concentrated water after passing through the purified water. As a result, only about 20% of the raw water is used as purified water, which is very uneconomical. For this reason, although the water purifier which uses a reverse osmosis membrane with the high recovery rate which exceeds the value of a manufacturer recommendation is also provided, there existed a problem that a membrane lifetime became short in such a water purifier.

  Therefore, without increasing the membrane recovery rate above the specified value, the recovery efficiency of the entire water purification device is improved, and the ratio of the total amount of purified water generated from raw water as the entire water purification device (hereinafter referred to as “system recovery rate”) ) And a number of such devices are already known.

  Specifically, a single-stage system (see FIG. 1) in which the number of reverse osmosis membrane modules is increased and arranged in series is known as the simplest means for improving the system recovery rate. In addition, when the number of reverse osmosis membrane modules is limited, a recirculation annular channel system that reduces a part of the concentrated water discharged from the reverse osmosis membrane module to supply water is known (see FIG. 2). ).

  However, in the case of a conventional single-stage system water purifier, it is necessary to use a plurality of reverse osmosis membrane modules. In the case of a recirculation annular channel system water purifier, the amount of water required for circulation is supplied to the reverse osmosis membrane module. In order to do so, it was necessary to increase the capacity of the pump. Therefore, the apparatus becomes large-scale, resulting in high costs and disadvantages that it is difficult to use for general household use.

  By the way, this system recovery rate is very important as a factor that determines the quality of the purified water obtained as a result and the life of the reverse osmosis membrane, as well as the economy (cost).

  However, in the conventional single-stage system water purifier, recirculation annular channel system water purifier, and the like, it is very difficult to set such a system recovery rate in advance.

  In other words, factors that determine the system recovery rate must take into account internal factors such as pump capacity and membrane recovery rate as well as external factors such as water quality (tap water), water pressure, and temperature. In addition, among these factors, external factors are not always stable. Therefore, in order to maintain a stable system recovery rate, various factors must be considered and management should be performed to maintain an appropriate recovery rate. Had to do.

  Furthermore, in the case of the conventional recirculation annular channel system water purifier, only a part of the concentrated water discharged from the reverse osmosis membrane module is returned into the system, and the other concentrated water is discharged out of the system. In order to set and manage the system recovery rate, in addition to the above factors, the flow rate balance of the concentrated water had to be controlled.

JP-A-2005-279614

  Therefore, the present invention overcomes such disadvantages of the conventional water purification apparatus, improves the system recovery rate by circulating the system without draining the concentrated water as it is, and easily sets and manages the system recovery rate. An object of the present invention is to provide a water purifier that can be used.

  The present invention solves the above-mentioned problem of improving the system recovery rate, introduces raw water for purification supplied from a water supply tank into a reverse osmosis membrane module, performs membrane separation treatment, and uses permeate as purified water. In the water purification apparatus supplied to the outside, the concentrated water separated from the purified water by the reverse osmosis membrane module is returned to the water supply tank.

  Further, the present invention solves the problem that the system recovery rate can be easily set and managed, and the supply of the raw water for purification from the water supply tank is controlled by the amount of the raw water for purification. It is a water purifier characterized by.

  The water purifier of the present invention supplies all the concentrated water discharged from the reverse osmosis membrane module to the water supply tank, thereby supplying the concentrated water that has been treated as wastewater to the reverse osmosis membrane module again. By reusing it as raw water, the system recovery rate can be improved.

  Furthermore, since the water purification apparatus of the present invention controls the supply of raw water for water purification from the water supply tank by the amount of raw water for water purification, it is possible to easily set the ratio of purified water or concentrated water permeated from the raw water. Therefore, the system recovery rate can be easily set and managed without considering various factors.

  Hereinafter, one embodiment of the water purifier of the present invention will be specifically described with reference to the drawings. Note that the present invention is not limited to these embodiments.

  FIG. 3 is a drawing showing an outline of the processing flow of the water purifier according to this embodiment. In the figure, 1 is a water supply tank, 2 is a water supply pump, 3 is a pre-filter, 4 is a reverse osmosis membrane module, 5 is a flow adjustment valve, 11 is a water intake pipe, 11a is a water intake, , L1 indicates a water supply line, L2 indicates a return line, and L3 indicates an external supply line. Moreover, A shows a water intake limit line.

  As shown in FIG. 3, in the water purifier according to this embodiment, the water supply pump 2, the prefilter 3, and the reverse osmosis membrane module 4 are communicated from the water supply tank 1 via the water supply line L <b> 1. The reverse osmosis membrane module 4 is connected to a water supply port (not shown) via an external supply line L3, and is connected to a flow rate adjusting valve 5 and a water supply tank 1 via a return line L2. Yes.

  In the purified water production by the water purification apparatus shown in FIG. 3, first, raw water stored in the water supply tank 1 is fed toward the reverse osmosis membrane module 4 by the water feed pump 2. And it pre-processes by the pre filter 3 provided in the front | former stage of the reverse osmosis membrane module 4. FIG. By passing through the prefilter 3, insoluble matter such as rust and the like such as rust, halogenated carbon such as trihalomethane and trichloromethylene, chlorine, and organic matter that becomes an odor source are removed from the raw water.

  Next, the treated water of the prefilter 3 is sent to the reverse osmosis membrane module 4 where the reverse osmosis membrane treatment is performed. By this treatment, 0.0001 μm or more of substances such as salts or microorganisms and viruses are removed, and purified water substantially free of impurities is obtained. Examples of the reverse osmosis membrane material used in the reverse osmosis membrane module 4 include materials such as cellulose acetate, polyamide, crosslinked polyamine, crosslinked polyether, and sulfonated polysulfone. Examples of the membrane element structure include a spiral type, a hollow fiber type, and a tube type. In the present invention, any kind of membrane may be used as the reverse osmosis membrane module. For example, a commercially available membrane can be appropriately selected and used.

  The purified water obtained by the pretreatment and the reverse osmosis membrane treatment is sent from the reverse osmosis membrane module 4 to the water supply port (not shown) via the external supply line L3, and from the water supply port, containers such as cups and bottles Supplied and used. On the other hand, the concentrated water separated from the purified water in the reverse osmosis membrane module 4 is returned to the water supply tank 1 from the reverse osmosis membrane module 4 via the return line L2 and the flow rate adjustment valve 5. The concentrated water returned to the water supply tank 1 is again subjected to pretreatment and reverse osmosis membrane treatment in the prefilter 3 and the reverse osmosis module 4 in the same manner as described above as raw water for purification. The purified water is supplied out of the system, and the remainder is returned to the water supply tank 1 again as concentrated water.

  As a result of repeating the above series of cycles, the remaining amount in the water supply tank 1 is (total amount of raw water before operation of the water purification apparatus) − (total amount supplied outside the system as purified water) unless natural evaporation or the like is considered. Become. In the present embodiment, when the remaining amount in the water supply tank 1 reaches a water level lower than the intake limit line A, which is the water level in contact with the intake port 11a portion of the intake pipe 11, water intake from the intake port 11a cannot be performed. At that time, water intake from the water supply tank 1 is stopped. That is, it becomes possible to control the supply of the raw water for water purification from the water supply tank by the amount of the raw water for water purification.

  The intake limit line A, which is a reference for control, can be determined, for example, by setting the position (height) of the intake port 11a, and such position (height) setting is simply relative to the water supply tank 1 of the intake pipe 11. What is necessary is just to raise and lower an attachment position. In addition to such a method, a water level sensor may be provided inside and outside the water supply tank 1, and water intake from the water supply tank 1 may be stopped when the remaining amount in the water supply tank 1 reaches an arbitrary water level. .

  After the water intake from the water supply tank 1 is stopped, the raw water for purification remaining in the water supply tank is discharged out of the system, and the raw water for purification is newly supplied to the tank. This process may be performed manually or may be automated. However, in the case of automation, a drain pipe and a water supply pipe are connected in advance to the water supply tank 1 in order to automatically supply the raw water after automatically discharging the raw water for purification remaining in the water supply tank out of the system. There is a need.

  In the water purifier of the present invention, the concentrated water is returned to the water supply tank 1 without being discharged out of the system and becomes raw water for water purification again, so that the total dissolved substances (Total Dissolved Solids) in the water supply tank 1 ) Concentration (hereinafter referred to as “TDS concentration”) becomes higher as purified water permeated from raw water is supplied out of the system. Therefore, before the TDS concentration of the raw water is extremely increased and the clogging of the membrane and the quality of the purified water are affected, it is necessary to stop the water intake from the water supply tank 1 and the water purification treatment.・ Management is important.

  Next, the system recovery rate setting method in the water purifier of the present invention will be described. First, when the system recovery rate is set to 50%, the position (height) of the water intake port 11a may be set to a position corresponding to exactly half the water level when the water tank 1 is full. By setting in this way, when the amount corresponding to 50% of the total amount of raw water in the water supply tank 1 is supplied outside the system as purified water, the water intake from the water supply tank 1 is stopped and the water purification treatment is stopped. Is done. As a result, the ratio of raw water to purified water is 5: 5, and a system recovery rate of 50% can be achieved.

  In order to change the setting of the system recovery rate, it is only necessary to change the setting of the position (height) of the intake port 11a. That is, when the system recovery rate is set to 70%, the position (height) of the intake port 11a may be set to a position corresponding to exactly 30% of the water level when the water supply tank 1 is full. According to this method, it is possible to easily set and change the system recovery rate without considering various factors such as pump capacity, membrane recovery rate, water quality of supply water (tap water), water pressure, temperature, etc. It becomes.

  In the water purifier of the present invention, the membrane recovery rate and the purified water production efficiency (the amount generated per hour) can be adjusted by adjusting the flow rate adjusting valve 5 to adjust the flow rate of the concentrated water. However, since the water purifier of the present invention is a closed circulation system, it goes without saying that the system recovery rate is not affected by the change in the membrane recovery rate or the purified water production efficiency.

Test example:
When the water purification apparatus having the structure shown in FIG. 1 is used and continuously operated, the TDS concentration of purified water and concentrated water and the percentage of the total soluble substances of raw water that do not pass through the reverse osmosis membrane (hereinafter, "Removal rate") was measured.

  This measurement starts with a water tank volume of 20 liters, under conditions of TDS concentration of raw water of 112.8 ppm, raw water temperature of 19 ° C., membrane recovery rate of 16.2%, and system recovery rate of 75%. Every time 1 liter of purified water is separated and produced (the amount of water in the water supply tank is reduced by 1 liter), the TDS concentration of purified water and concentrated water (in the table, “R.O.TDS” and “drainage TDS” And the removal rate was measured. The results are shown in Table 1.

  From this test result, it can be seen that as the amount of water in the tank decreases, the TDS concentration of the raw water increases, but the removal rate is maintained in the range of approximately 98-99%, so the TDS concentration of purified water is also Although it is a little higher, the TDS concentration is within the range of 2.2 to 5.7% of the original raw water TDS (112.8 ppm), and it became clear that there is no problem with the water purification function.

  The water purifier of the present invention described above has various features. That is, due to the presence of the water supply tank provided in the system, the TDS rises gradually, and since the raw water is periodically exchanged, the TDS itself also decreases, so the burden on the RO membrane is small. . In addition, the presence of the water supply tank eliminates the need to adjust the amount of drainage and pressure when the water temperature fluctuates, which is essential for a conventional water purifier using an RO membrane, and makes it possible to fix the system recovery rate.

  As described above, the water purifier according to the present invention can improve the system recovery rate and can easily set and manage the system recovery rate. Since a circulation system that is not required is adopted, it is possible to supply purified water as a self-supporting water supply station, for example, even in a place where it is difficult to install a water supply pipe.

Conventional single-stage system Conventional recirculation annular channel system Schematic of processing flow of water purification apparatus according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... Water supply tank 2 ...... Water feed pump 3 ...... Pre-filter 4 ...... Reverse osmosis membrane module 5 ...... Flow control valve 11 ...... Water intake pipe 11a ...... Water intake L1 ...... Water supply line L2 ...... Return line L3 …… Off-system supply line A…… intake limit line
more than

Claims (4)

  Concentrated water separated from purified water by the reverse osmosis membrane module in a water purification apparatus that introduces raw water for purification supplied from a water supply tank into a reverse osmosis membrane module, performs membrane separation treatment, and supplies permeate as purified water to the outside of the system Is returned to the water supply tank.   The water purifier according to claim 1, wherein the supply of the raw water for water purification from the water supply tank is controlled by the amount of the raw water for water purification.   Control by the amount of raw water for water purification is performed by arbitrarily setting the height of the water intake in the water supply tank and stopping the supply when the water level in the tank falls below the height of the water intake The water purifier according to claim 2. 4. The water supply tank according to claim 1, further comprising means for automatically draining concentrated water in the tank out of the system and automatically replenishing raw water from outside the system. Water purification device.

Images