JPH05212252A - Reverse-osmosis liquid separator - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the separator due to scaling on the reverse-osmosis membrane surface by filtering a raw water with a hollow-fiber filter membrane module unit and then supplying the filtered water to a reverse- osmosis liq. separator. CONSTITUTION:A hollow-fiber membrane module capable of regeneration by cleaning is furnished to the separator. A raw water introduced from a line 1 is passed through a feed water line 3 by a pump 2 and sent to a hollow-fiber filter membrane module 6, and the fine particles, suspended matter, bacteria, algae, etc., are filtered off. The filtered water is sent to a reverse-osmosis membrane module 9 through a line 8. The treated water is pressurized by a pump 12, passed through the module 9 and separated, the permeated water is taken out of a line 10, and the concd. water is discharged from a line 11. Consequently, the life of the pretreating filter membrane module is drastically extended, and the module is hardly exchanged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention filters raw water in advance by a hollow fiber filtration membrane module whose performance can be recovered by a washing operation, and then reverse osmosis liquid separation by a reverse osmosis membrane module unit using a semipermeable membrane. The present invention relates to a liquid separation device for performing.

[0002]

2. Description of the Related Art Liquid separation by a reverse osmosis method using a semipermeable membrane has been put to practical use in various fields such as seawater desalination, ultrapure water production, and solution concentration. The membrane module used in the reverse osmosis method is mainly a spiral type or a hollow fiber type, but if the target raw water is directly supplied to the reverse osmosis membrane module, fine particles, suspensions, bacteria, and algae inside the membrane module. Clogging is likely to occur due to dust and the like, and fouling occurs on the membrane surface, which is a factor that greatly reduces the membrane separation performance. Therefore, when the liquid is separated by the reverse osmosis membrane module, a low pressure type reverse osmosis membrane (loose R) is used as pretreatment filtration.
O), ultrafiltration membranes (UF), microfiltration membranes (MF), filters, various filter media, etc. are often used to remove fine particles and the like.

[0003]

However, even when it is possible to prevent the performance of the reverse osmosis membrane module unit from deteriorating by performing the pretreatment filtration as described above, the pretreatment filtration unit causes clogging or the like. However, since the performance cannot be exhibited, there is a problem that the replacement work has to be performed after using for a certain period of time.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hollow fiber filtration membrane capable of recovering its performance by preliminarily washing a raw water in a liquid separating apparatus for performing reverse osmosis separation of a liquid using a semipermeable membrane. It is basically achieved by a reverse osmosis liquid separation device which is characterized in that it is filtered in a module unit and then fed to a reverse osmosis membrane module unit.

FIG. 1 is an example of a circuit diagram of a reverse osmosis liquid separation device equipped with a hollow fiber membrane module capable of recovering performance by a washing operation according to the present invention. As shown in this figure,
Raw water taken from the raw water line 1 is sent by a feed water pump 2 through a feed water line 3 to a hollow fiber filtration membrane module 6 to filter fine particles, suspensions, bacteria, algae, etc.
Remove. The filtered water is sent to the reverse osmosis membrane module 9 through the line 8. In the reverse osmosis membrane module 9, the treated water is pressurized by the pump 12 to separate the treated water, the permeated water is taken out from the line 10, and the concentrated water is discharged from the line 11.

Further, as the operation continues, when the blocked substance deposits on the membrane surface of the hollow fiber filtration membrane module 6 as a scale, the feed water pump 2 is stopped, the valve 13 is closed, and , 14 is opened, the air pump 5 is operated, and the air in the module 6 is bubbled, whereby the hollow fiber membrane surface is vibrated and the membrane surface deposit can be removed. The performance of the hollow fiber filtration membrane module is restored by discharging the water containing the removed deposits from the drain valve 4.

In the filtration by the hollow fiber filtration membrane module, the total amount of feed water is generally filtered, but so-called cross flow filtration for discharging a part of the feed water as shown in FIG. 2 causes no problem. .. In addition, it is possible to install a flow rate adjusting device, a pressure adjusting device, and an automatic cleaning device as needed.

Further, a method using air bubbling is effective for washing the hollow fiber membrane, but washing by reverse water flow (back washing) from the permeate side to the feed side of the hollow fiber membrane by filtered water or clear water is effective. , Also, the combination of these can be used at all. Moreover, it is also possible to perform cleaning with a chemical solution as needed.

Although the shape of the hollow fiber filtration membrane module is not particularly limited, it can be easily washed by air bubbling, as shown in FIG. 3 (JP-A-60-206415) and FIG. 4 (JP-A-61-263).
It is desirable that the shape as shown in 605).

The reverse osmosis liquid separation device of the present invention can be applied to various fields such as desalination of seawater, production of pure water, clarification and concentration of juice. In addition, depending on the application, various filters, precision filtration equipment, ion exchangers,
The target liquid can be produced by using a degassing membrane device, a chemical addition device, a sterilization treatment device and the like together. In particular, when used for ultrapure water production, the basic procedure is to perform pretreatment in the hollow fiber filtration membrane module unit, pass it through the reverse osmosis membrane module unit, and then supply the treated permeate to the ion exchanger unit. In addition, primary pure water can be produced by an apparatus having three units as shown in FIG. Furthermore, ultrapure water can be obtained by passing through ultraviolet irradiation, a non-regeneration type ion exchanger unit, and an ultrafiltration membrane module unit.

One of the applications of the reverse osmosis liquid separation device of the present invention is the use of the device on a ship.
There are quite a few cases where fresh water is required on a ship, especially when sailing over long distances and long hours. Especially when used in fisheries, large quantities are often required. The main use is for preservation of fish. In order to land the captured fish fresh, it is necessary to use salt water having a lower salt concentration than sea water, and for that purpose fresh water for diluting sea water is required. Naturally, it is disadvantageous in terms of time and cost to carry out fishing with a large amount of water, and availability of fresh water at the fishing destination is a very important issue. In such a case, the problem can be solved by mounting a reverse osmosis liquid separation device for desalinating seawater on the ship. However, in seawater,
There are many particles, suspensions, algae, bacteria, and many other factors that reduce the performance of the reverse osmosis membrane module unit. Therefore, as described above, the pretreatment filtration membrane module unit is required. Moreover, it is difficult to replace the filtration membrane module unit during voyage, and even if it is possible, it is disadvantageous to carry the spare unit together. Furthermore, when operating near land, seawater is often contaminated and the service life of the filtration membrane module unit is not constant. Therefore, all of these problems can be solved by using a filtration membrane module unit whose performance can be recovered by washing work, which is an extremely effective means. Further, when using the hollow fiber filtration membrane module unit described above,
Since it is possible to perform cleaning by air bubbling and no chemical solution is required, cleaning at sea is easy and there is no need to worry about drug contamination.

[0012] In addition, bath water used for luxury passenger ships, cruisers, ferries, etc. are also included in the ship loading applications.
As an emergency, it can also be used for drinking water.

The reverse osmosis liquid separation membrane module unit is
There are various types of desalination rate and water production depending on the application. For example, for fisheries, it is appropriate to use a low-pressure type that has a low desalination performance and a high amount of fresh water, and for the purpose of using it as drinking water, a high-pressure type that has a high desalination performance is used. It is suitable to use.

The hollow fiber membrane material constituting the hollow fiber filtration membrane module used in the present invention is not particularly limited as long as it is a porous hollow fiber, but polyethylene, polypropylene,
Polysulfone, polyether sulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, polytetrafluoroethylene, etc. can be used. Among these, as a preferable material, a polymer or an olefin-based polymer having at least one component of acrylonitrile, and particularly preferably 50 mol% or more of acrylonitrile, and more preferably 60 mol% or more with respect to the acrylonitrile. It is an acrylonitrile-based copolymer composed of one or more vinyl compounds having copolymerizability. Also, a mixture of two or more of these acrylonitrile-based copolymers and further other polymers may be used. The vinyl compound may be any known compound having copolymerizability with acrylonitrile, and is not particularly limited, but preferable copolymer components include acrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, Examples thereof include vinyl acetate, sodium allyl sulfonate, sodium p-styrene sulfonate, and the like.

The next preferred hollow fiber membrane material comprises one or more olefin polymers such as ethylene, propylene and 4-methylpentene, and has a hollow fiber membrane shape having a major axis of 0.1 to 1.0 μm on the surface. ， Short axis 0.05〜
Those having 0.5 μm slit-shaped pores are suitable.

The reverse osmosis liquid separation membrane module used in the present invention is not limited to a flat membrane type, a hollow fiber membrane type, a spiral type, and the like, but the filling rate of the membrane can be increased.
It is preferable that the pressure resistance is high. A spiral type module or a hollow fiber membrane module is particularly preferable. The spiral type module has a basic structure in which an envelope-shaped membrane is wrapped around a porous central tube together with a net-shaped channel material, and is widely known as a membrane separation module. The hollow fiber membrane module is not particularly limited in type, but it is desirable that the hollow fiber membrane module has a structure in which feed water and permeate water are less likely to cause a nonuniform flow, and clogging due to scale formation is less likely to occur.

The membrane used in the spiral wound type membrane module is generally an asymmetric membrane or a composite membrane, but a composite membrane is particularly common. The membrane structure called a composite membrane has a flat membrane shape and is composed of a porous support layer and a polymer homogeneous layer or a dense layer provided thereon. The porous support layer has a function of preventing mechanical deformation of the polymer homogeneous layer as a support layer of the polymer homogeneous layer that most affects the performance of the hydrophobic gas permeable membrane, and has sufficient gas permeability. It is necessary to have In order to further increase the strength of the support layer, it is preferable to have a reinforcing layer such as a polyester woven fabric or a non-woven fabric under the support layer. Examples of preferable polymer of the porous support layer include polyester, polyamide, polyolefin, polyacrylate, polymethacrylate, polytetrafluoroethylene, polysulfone, and polycarbonate, but polysulfone or polypropylene is particularly preferable. .. Specific examples of the polymer homogeneous layer formed on the porous support layer include polyether-based, aromatic polyamide-based, aliphatic polyamide-based, polyethyleneimine-based, and polyethylene oxide. Among these, among these, Even when the permeation performance is improved by making it thin, it is preferable to use an aromatic cross-linked polyamide which is excellent in blocking performance and has high chemical resistance. Also, for asymmetric membranes,
Practicality is high because the cellulose acetate type membrane has excellent separation performance, durability and chemical resistance.

[0018]

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to this.

Example 1 In the degassing membrane device having a circuit as shown in FIG. 1 which is an example of the present invention, the hollow fiber filtration membrane module has an inner diameter of 350 μm.
m, an outer diameter of 500 μm, and a length of 1 m were loaded with 20000 polyacrylonitrile porous hollow fibers. Also, as the reverse osmosis membrane module, a liquid separation membrane in which a thin film of aromatic polyamide is formed on a support made of polyester taffeta / polysulfone, a permeation side flow path material made of polyester fabric having vertical grooves, and a polypropylene net are used. A spiral-type material was used, which was wound around a porous central tube made of hard vinyl chloride together with the flow-side channel material consisting of.

Industrial water was used as raw water to be treated, and the hollow fiber filtration membrane module was washed by air bubbling for 15 minutes at intervals of 24 hours. The liquid separation test was carried out using seawater, and 10 liters per minute was flowed at a pressure of 56 Kg / cm ² . At this time, the change with time of the permeation flow rate was measured to examine the stability of the water producing performance of the device. As a result, the permeation flow rate at the initial stage was 3.1 m ³ / day, and there was almost no change in the water production performance even after 30 days.

Comparative Example 1 A seawater desalination test was carried out under the same conditions as in Example 1 using a liquid separator as shown in FIG. 6 which is the same as in Example 1 except that the hollow fiber filtration membrane module was not equipped. It was As a result, the initial water production performance was 3.0 m ³ / day, but 10
After a day, the water production performance decreased to 1.6 m ³ / day.

[0022]

INDUSTRIAL APPLICABILITY In the present invention, in a liquid separation apparatus for performing reverse osmosis separation of a liquid using a semipermeable membrane, raw water is previously filtered by a hollow fiber filtration membrane module unit whose performance can be recovered by a washing operation, The performance of the reverse osmosis membrane module is maintained by the reverse osmosis liquid separation device, which is then supplied to the reverse osmosis membrane module unit, while the life of the filtration membrane module for pretreatment, which has been a problem in the past, is significantly extended. Therefore, the replacement of the filtration membrane module became almost unnecessary.

[Brief description of drawings]

FIG. 1 is an example of a circuit diagram of a reverse osmosis liquid separation device according to the present invention.

FIG. 2 is an example of a circuit diagram of a reverse osmosis liquid separation device according to the present invention.

FIG. 3 is an example of a hollow fiber filtration membrane module used in the reverse osmosis liquid separation device according to the present invention.

FIG. 4 is an example of a hollow fiber filtration membrane module used in the reverse osmosis liquid separation device according to the present invention.

FIG. 5 is an example of a circuit diagram of a liquid separator for producing pure water according to the present invention.

FIG. 6 is an example of a conventional reverse osmosis liquid separation device.

FIG. 7 is an example of a reverse osmosis liquid separation device having a conventional pretreatment filtration device.

[Explanation of symbols]

 1: Raw water line 2: Supply water pump 3: Supply water line 4: Drain valve 5: Air pump 6: Hollow fiber filtration membrane module 7: Air bleeding valve 8: Filtration water line 9: Reverse osmosis membrane module 10: Permeate water line 11 : Concentrated water line 12: High pressure pump 13: Check valve 14: Check valve 15: Check valve 16: Drain line 17: Valve 18: Raw water supply port 19: Concentrated water outlet 20: Permeate outlet 21: Hollow fiber membrane 22: Circulation line 23: Ion exchanger 24: Pure water 25: Concentrated water valve 26: Filtration membrane module

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C02F 1/42 A 9/00 Z 8515-4D

Claims (5)

[Claims] 1. A liquid separation apparatus for reverse osmosis separation of a liquid using a semipermeable membrane, wherein raw water is previously filtered by a hollow fiber filtration membrane module unit whose performance can be recovered by washing operation, and then reverse osmosis is performed. A reverse osmosis liquid separation device characterized by supplying to a membrane module unit. 2. The structure of the reverse osmosis membrane module is a spiral type module, and the reverse osmosis membrane is a polyether composite membrane,
The reverse osmosis liquid separation device according to claim 1, wherein the reverse osmosis liquid separation device is any one of an aromatic polyamide-based composite membrane, an aliphatic polyamide-based composite membrane, and a cellulose acetate-based asymmetric membrane. 3. The reverse osmosis liquid separation according to claim 1, wherein the porous hollow fiber membrane constituting the hollow fiber filtration membrane module is made of a polymer or an olefin polymer having at least one component of acrylonitrile. apparatus. 4. Raw water is filtered in advance by a hollow fiber filtration membrane module unit whose performance can be recovered by a washing operation and then supplied to the reverse osmosis membrane module unit, after which the treated permeated water of the reverse osmosis membrane module unit is exchanged with an ion exchanger. A reverse osmosis liquid separation membrane device characterized by being supplied to a unit for treatment. 5. The reverse osmosis liquid separation membrane device according to claim 1, wherein the main purpose of use is for ship loading.