JP2009262124A - Method and apparatus for purification treatment of metal component-containing water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purification treatment method of metal component-containing water capable of reducing the treatment load of concentrated water formed by reverse osmosis membrane separation. <P>SOLUTION: The purification treatment method of the metal component-containing water is characterized by executing a reverse osmosis membrane separation process wherein the metal component-containing water, in which a metal component is dissolved, is separated into purified water being permeated water and concentrated water by reverse osmosis membrane separation, an electrolytic process for electrolyzing the concentrated water to obtain alkaline water from a cathode side and a precipitate removing process for removing the metal component, which is precipitated by making the metal component-containing water alkaline, from the alkaline water obtained in the electrolytic process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for purifying metal component-containing water to obtain purified water by reverse osmosis membrane separation of metal component-containing water such as sewage in which metal components are dissolved, factory effluent, ground water, river water, landfill leachate, seawater, The present invention relates to a purification processing apparatus.

Conventionally, this type of purification treatment method includes a turbidity step in which a metal component-containing water in which a metal component is dissolved is turbidized by a turbidity device such as an MF membrane filtration device, and a turbidity removal by the turbidity step. There is known a method of performing a reverse osmosis membrane separation step of separating turbid treated water into permeated water and concentrated water by reverse osmosis membrane separation.
In such a method, the permeated water by reverse osmosis membrane separation is treated as purified water, and the concentrated water contains many metal components. Therefore, the concentrated water cannot be discarded as it is. It is processed by solidifying the landfill.
JP 2003-103259 A

  However, the conventional purification method described above requires a large burden on the treatment of the concentrated water, for example, it requires a lot of energy to evaporate the water in the treatment of the concentrated water generated by the reverse osmosis membrane separation. Has the problem of becoming.

  In view of the above-mentioned conventional problems, an object of the present invention is to provide a purification method and a purification treatment apparatus for metal-containing water that can at least reduce the treatment burden of concentrated water produced by reverse osmosis membrane separation.

In order to solve the above problems, the present invention provides a metal component-containing water for carrying out a reverse osmosis membrane separation step of separating metal component-containing water in which a metal component is dissolved into purified water and concentrated water as permeated water by reverse osmosis membrane separation. The electrolytic treatment step of electrolyzing the concentrated water to obtain alkaline water from the cathode side, and filtering the metal component deposited by becoming alkaline from the alkaline water obtained in the electrolysis step The present invention provides a method for purifying metal component-containing water, characterized by performing a precipitate separation step of separating.
In such a method for purifying metal component-containing water, alkaline water in which the metal component is concentrated on the cathode side can be obtained by electrolysis in the electrolysis step, and it becomes alkaline by the precipitate separation step. Thus, the deposited metal component can be separated by filtration. Therefore, it is possible to remarkably reduce the processing load of evaporation and concentration for precipitation and solidification of the metal component. The metal component separated by filtration can be removed by backwashing, for example. At this time, the generated backwash waste liquid can contain a metal component at a much higher concentration than the concentrated water separated by the reverse osmosis membrane. Therefore, even when backwashing is performed, the processing load of evaporation concentration can be remarkably reduced.

In the present invention, a turbidity step is performed in which the metal component-containing water before the reverse osmosis membrane separation step is turbidized by a turbidity removing device. It is preferable that the turbid metal component-containing water is separated by reverse osmosis membrane, and in the precipitate separation step, the deposited metal component is separated by the turbidity removing device.
In such a method, the burden on the reverse osmosis membrane can be reduced by removing the turbidity in advance in the turbidity removing step. In addition, in the precipitate separation process, since the turbidity device used in the turbidity process is used, it is not necessary to provide a separate turbidity device, and the processing load of concentrated water can be further reduced in terms of the cost of the device. Can do.

Further, in the present invention, in the electrolysis step, a neutralization step is performed in which acidic water is obtained from the anode side and neutralized by adding the acidic water to the alkaline water from which the metal component has been removed by the precipitate separation step. Is preferred.
Alkaline water from which the deposited metal component has been separated through the precipitate separation step is usually neutralized and discarded, but in such a method, as an additive for neutralization, Since acidic water obtained from the anode side in the electrolysis step is used, it is not necessary to separately prepare or generate acidic water, and the treatment load of the concentrated water generated can be further reduced.

In addition, the turbidity removing device is preferably a device that removes turbidity by filtration using an MF membrane or a UF membrane.
In such a method, since the turbidity removal apparatus using the MF membrane or the UF membrane can separate the deposited metal component relatively easily, the treatment load of the concentrated water can be further reduced.

Furthermore, in the present invention, the pH of the alkaline water is preferably 9-14.
In such a method, by setting the pH of the alkaline water to 9 or more, the metal component can be sufficiently precipitated, and the precipitated metal component can be sufficiently separated by the turbidity remover. The burden can be reduced. Moreover, if it is pH 14 or less, a possibility of damaging a turbidity apparatus (for example, MF film | membrane etc.) is also reduced.

  The present invention is also a metal component-containing water purification treatment apparatus having a reverse osmosis membrane separation device that separates metal component-containing water in which a metal component is dissolved into purified water that is permeated water and concentrated water using a reverse osmosis membrane. Further, an electrolyzer that electrolyzes the concentrated water to obtain alkaline water from the cathode side, and a precipitate separator that separates metal components deposited by becoming alkaline from the alkaline water obtained by the electrolyzer It is intended to provide a purification apparatus for water containing metal components, characterized by comprising:

  As described above, according to the present invention, it is possible to at least reduce the processing load of concentrated water generated by reverse osmosis membrane separation.

Embodiments of the present invention will be described below with reference to the drawings.
First, the purification processing apparatus of metal component containing water is demonstrated.
FIG. 1 is a schematic flow diagram in the metal component-containing water purification treatment apparatus of the present embodiment.
The metal component-containing water purification treatment apparatus of the present embodiment normally removes the raw water tank 10 that stores the raw water A that is the metal component-containing water in which the metal component is dissolved, and the raw water A that is supplied from the raw water tank 10. The turbidity removal device 20, the reverse osmosis membrane separation device 30 for separating the turbidity-treated water turbidized by the turbidity removal device 20 into the purified water as the permeate B and the concentrated water C by the reverse osmosis membrane, and the concentrated water The electrolysis apparatus 40 which electrolyzes C and obtains the alkaline water D from the cathode side, and the deposit separation apparatus 50 which isolate | separates the metal component which precipitated by becoming alkaline from the alkaline water D obtained by this electrolysis apparatus 40 are provided. ing.

The raw water tank 10 is configured as a tank for storing the raw water A.
Examples of the raw water A include sewage, biologically treated water of sewage, factory effluent, ground water, river water, landfill leachate, seawater, and the like.
Moreover, as a metal component contained in these raw | natural water A, calcium, magnesium, iron, aluminum etc. can be mentioned.

The turbidity removal device 20 is communicated with the raw water tank 10 through a pipe having a pump interposed therein, so that the raw water A stored in the raw water tank 10 is supplied, and further supplied. A filter member for filtering the raw water A is provided so that the raw water A can be turbidized.
Examples of the filtration member include a membrane member 21 such as a microfiltration membrane (MF membrane) and an ultrafiltration membrane (UF membrane), and a filtration member provided with a sand filtration layer used for sand filtration.
The membrane member 21 is preferably provided with a microfiltration membrane.
In this specification, turbidity is filtration that is coarser than reverse osmosis membrane filtration, that is, performed before reverse osmosis membrane separation, and removes impurities that are coarser than those separated by reverse osmosis membrane. means.

In the purification treatment apparatus of the present embodiment, the turbidity-treated water that has been turbidized by the turbidity removal apparatus 20 through a pipe is supplied to the reverse osmosis membrane separation apparatus 30. Specifically, the turbidity-treated water tank 22 in which the turbidity-treated water turbidized by the turbidity removing device 20 is stored is provided, and the turbidity-treated water in the turbidity-treated water tank 22 is reverse osmosis through a pipe having a pump interposed therein. It is supplied to the membrane separator 30.
Further, if necessary, the turbidity removal device 20 can be washed back (so-called backwashing) by causing the turbidity treatment water or the like to flow backward to the turbidity removal device 20.

  The reverse osmosis membrane separation device 30 includes a reverse osmosis membrane 31 (RO membrane 31), and the supplied turbidity-treated water is dissolved with purified water as permeated water B having almost no dissolved metal component by reverse osmosis membrane separation. The metal component is separated into concentrated water C that is concentrated.

  The permeated water B is usually set to have an electric conductivity of 200 μS / cm or less, preferably 50 μS / cm or less. The concentrated water C has an electric conductivity of 3000 to 15000 μS / cm, preferably 5000 to 10,000 μS / cm.

In the purification treatment apparatus of the present embodiment, the permeated water B is discharged out of the system by piping, and the concentrated water C is supplied to the electrolyzer 40.
Specifically, a concentrated water storage tank 33 in which the concentrated water C is stored is provided, and the concentrated water C stored in the concentrated water storage tank 33 is supplied to the electrolyzer 40 through a pipe having a pump interposed therein. ing.

The electrolysis apparatus 40 includes an electrolysis tank 41 having a cathode and an anode for storing the supplied concentrated water C, and the electrolysis tank 41 is divided into a cathode side and an anode side by a diaphragm 42. . Examples of the diaphragm 42 include a microporous membrane such as an MF membrane or an ion exchange membrane.
The electrolyzer 40 is configured to electrolyze the concentrated water C by applying a voltage to the cathode and the anode.
In the electrolyzer 40, when electrolysis is performed, metal components concentrate on the cathode side and hydroxyl ions are generated, so that alkaline water D can be obtained from the cathode side, and vice versa from the anode side. Thus, acidic water E can be obtained.

  The alkaline water D is usually adjusted to have a pH of 9 to 14, preferably 10 to 12.

In the purification treatment apparatus of the present embodiment, the alkaline water D is further supplied to the precipitate separation apparatus 50 by piping.
In detail, the alkaline water storage tank 44 in which the alkaline water D is stored is provided, and the alkaline water D stored in the alkaline water storage tank 44 passes through a pipe in which a pump is interposed, thereby removing the turbidity as the precipitate separator 50. Returned to the device 20.
When the alkaline water D stored in the alkaline water storage tank 44 does not reach the predetermined pH value, at least a part of the alkaline water D is circulated and returned to the cathode side of the electrolytic tank 41 to store the alkaline water storage. The pH of the alkaline water D in the tank 44 is adjusted.

The turbidity removal device 20 as the precipitate separation device 50 is configured such that a metal component precipitated by becoming alkaline from the supplied alkaline water D is filtered and separated by the filtration member 21.
In the purification apparatus of this embodiment, the alkaline water D from which the deposited metal component has been separated is supplied to a neutralization tank 60 for neutralizing the alkaline water D.
Further, the turbidity removal device 20 can be backwashed by backflowing turbidity-treated water or the like, and the solid components such as metal components and suspended substances filtered and separated by backwashing are backwash waste liquid. In a state where F is contained in a high concentration, it is stored in the backwash waste liquid storage tank 23 and discharged out of the system.
In addition, the backwash waste liquid F containing the metal component discharged | emitted out of the system in high concentration will be water-treated by a conventionally well-known method.

  In the present embodiment, examples of the metal component deposited from the alkaline water D include calcium, magnesium, iron, aluminum, and the like. These include, for example, calcium carbonate, magnesium carbonate, iron hydroxide, It is deposited in the form of an inorganic salt such as aluminum hydroxide.

In the purification treatment apparatus of the present embodiment, the acidic water E is further supplied to the reverse osmosis membrane separation device 30 and further supplied to the neutralization tank 60 by piping.
Specifically, it includes an acidic water storage tank 46 in which the acidic water E is stored, and the acidic water E stored in the acidic water storage tank 46 is supplied to the reverse osmosis membrane separation device 30 through a pipe interposed with a pump, The acidic water E that has washed the reverse osmosis membrane 31 is configured to be supplied to the neutralization tank 60.
When the acidic water E stored in the acidic water storage tank 46 does not reach a predetermined pH value, at least a part of the acidic water E is circulated back to the anode side of the electrolytic tank 41 to store the acidic water. The pH of the acidic water E in the tank 46 is adjusted.
The purification treatment apparatus of the present embodiment can further circulate and return the acidic water E that has been supplied to the reverse osmosis membrane separation device 30 and washed the reverse osmosis membrane 31 to the acidic water storage tank 46 by piping. ing. Specifically, the acidic water E that has been circulated and returned is supplied to the reverse osmosis membrane separation device 30 again to wash the reverse osmosis membrane 31 and then supplied to the neutralization tank 60. It has become.
In the neutralization tank 60, the alkaline water D and the acidic water E that have passed through the precipitate separator 50 are mixed and neutralized.
Further, the neutralized water G neutralized in the neutralization tank 60 is supplied to the raw water tank 10 through a pipe provided with a pump, or is supplied outside the system via the backwash waste liquid storage tank 23. It is supposed to be discharged.
The neutralized water G discharged out of the system is treated with water by a conventionally known method.

In the present embodiment, since the acidic water E is supplied to the reverse osmosis membrane separation device 30, the scale and bacteria attached to the reverse osmosis membrane 31 are removed.
Here, the acidic water E is usually adjusted to have a pH of 1 to 5, preferably 2 to 4.
With such a pH, sufficient scale removal and sterilization can be performed without damaging the reverse osmosis membrane 31.

The metal component-containing water purification treatment apparatus of this embodiment is as described above. Next, the metal component-containing water purification treatment method of this embodiment will be described.
The purification treatment method of the present embodiment includes a turbidity process in which the raw water A, which is a metal component-containing water in which a metal component is dissolved, is turbidized by the turbidizer 20, and the turbidity-treated water turbidized in the turbidity process. A reverse osmosis membrane separation step of separating the concentrated water C into purified water and concentrated water C as permeated water B by reverse osmosis membrane separation to obtain alkaline water D from the cathode side by electrolyzing the concentrated water C and acidic water from the anode side An electrolysis step for obtaining E, a precipitate separation step for filtering and separating the metal component deposited by becoming alkaline from the alkaline water D obtained in the electrolysis step, and a turbidizer by backwashing the metal component separated by filtration The neutralization process which mixes and neutralizes the backwashing process which removes from 20 and discharges the backwash waste liquid containing the removed metal component etc., and the alkaline water and the acidic water E which passed through the said precipitate separation process And carry out.
In the present embodiment, the separated metal component is separated by the precipitate separation step, and the waste water treatment is performed on the backwash waste liquid containing the metal component at a high concentration. Can be reduced, and the processing burden can be remarkably reduced.

In the turbidity removing step, suspended components such as mud contained in the raw water A are removed by, for example, membrane filtration.
Such a process can reduce the possibility that the reverse osmosis membrane 31 used in the reverse osmosis membrane separation step is damaged by the suspended components.

In the reverse osmosis membrane separation step, the raw water A from which suspended components have been removed in the turbidity step is separated into permeated water B and concentrated water C enriched with metal components by reverse osmosis membrane separation.
In the present embodiment, since the reverse osmosis membrane 31 is used, purified water with extremely high purity from which dissolved metals are removed can be obtained.
The permeated water B usually has an electric conductivity of 200 μS / cm or less, preferably 50 μS / cm or less. The concentrated water C usually has an electric conductivity of 3000 to 15000 μS / cm, preferably 5000 to 10,000 μS / cm.

In the electrolysis process, the concentrated water C generated by the reverse osmosis membrane process is separated into the alkaline water D on the cathode side and the acidic water E on the anode side by electrolysis.
The voltage applied during the electrolysis is usually 1 to 5 V, preferably 2 to 3 V.
By setting it as such a voltage, the concentrated water C can fully be electrolyzed.
Moreover, the time of electrolysis is not specifically limited, It continues until the pH of the alkaline water D becomes 9-14, and the pH of the acidic water E becomes 1-5.
By setting the alkaline water D to such a pH, the contained metal component can be sufficiently precipitated.
Further, by setting the acidic water E to such a pH, when the reverse osmosis membrane 31 is washed with the acidic water E, the scale can be sufficiently removed and sterilized, and damage to the reverse osmosis membrane 31 can be kept low. Can do.

In the precipitate separation step, the metal component deposited by becoming alkaline is separated from the alkaline water D obtained in the electrolysis step by filtration.
Specifically, a turbidity remover that uses metal components such as calcium, magnesium, iron, aluminum, and the like deposited in the form of inorganic salts such as calcium carbonate, magnesium carbonate, iron hydroxide, and aluminum hydroxide in the turbidity step. 20 to separate.

  In the neutralization step, the alkaline water D and the acidic water E that have passed through the precipitate separation step are supplied to the neutralization tank 60, and both are mixed and neutralized. Specifically, the alkaline water D that has undergone the precipitate separation step and the acidic water E that is the cleaning waste liquid that is supplied to the reverse osmosis membrane 31 and acid-washed the reverse osmosis membrane 31 are supplied to the neutralization tank 60. Neutralize.

  Furthermore, in this embodiment, the neutralized water G obtained in the neutralization step is mixed with the raw water A, and the same treatment is performed again together with the raw water A or via the backwash waste liquid storage tank 23. Or discharged outside the system.

The metal component-containing water purification treatment apparatus and purification treatment method in the present embodiment are as described above, but the metal component-containing water purification treatment apparatus and purification treatment method of the present invention are not limited to the above-described embodiment. The design can be changed as appropriate.
For example, in the purification treatment method of the present embodiment, in the neutralization step, cleaning waste liquid obtained by acid cleaning the reverse osmosis membrane 31 was used as the acidic water E, but in the present invention, it was obtained in the electrolysis step. The turbidity removal apparatus 20 may be acid-washed with the acid water E, and this washing waste liquid may be used as the acid water E in the neutralization step, and the acid water E obtained in the electrolysis step is not used for washing but is used as it is. You may use in a sum process.
Further, in the purification apparatus for water containing metal components according to the present embodiment, the backwash waste liquid storage tank 23 for storing the backwash waste liquid F and the neutralized water G is provided. In the present invention, The backwash waste liquid storage tank 23 may not be provided, and the backwash waste liquid F and the neutralized water G may be directly discharged out of the system. Similarly, in the purification treatment method, it may be discharged out of the system without going through the backwash waste liquid storage tank 23.
Furthermore, in the purification processing apparatus for metal component-containing water according to the present embodiment, the turbidity-treated water tank 22 for storing the turbidity-treated water is provided for backwashing of the turbidity-eliminating apparatus 20 or the like. However, the turbidity-treated water tank 22 is not provided. For example, the concentrated water C stored in the concentrated water storage tank 33, the acidic water E stored in the acidic water storage tank 46, the purified water B, etc. are backwashed. It may be configured to be supplied to the turbidity removal device 20 for use. Similarly, in the purification treatment method, the turbidity removal device 20 may be backwashed using concentrated water C, acidic water E, or purified water B without using the turbidity-treated water.

The schematic flowchart which shows the purification processing apparatus and method of the metal containing water of one Embodiment.

Explanation of symbols

20 ... Turbidity removal device 30 ... Reverse osmosis membrane separation device 40 ... Electrolysis device 50 ... Precipitate separation device

Claims (6)

A metal component-containing water purification treatment method for performing a reverse osmosis membrane separation step of separating metal component-containing water in which a metal component is dissolved into purified water that is permeated water and concentrated water by reverse osmosis membrane separation,
Further, an electrolysis step of electrolyzing the concentrated water to obtain alkaline water from the cathode side, and a precipitate separation step of filtering and separating the metal component deposited by becoming alkaline from the alkaline water obtained in the electrolysis step A method for purifying metal component-containing water, characterized in that it is carried out.   A turbidity step is performed in which the metal component-containing water before the reverse osmosis membrane separation step is turbidized by a turbidity apparatus, and in the reverse osmosis membrane separation step, the metal component containing turbidity in the turbidity step is contained. The method for purifying metal component-containing water according to claim 1, wherein water is separated by reverse osmosis membrane, and in the deposit separation step, the deposited metal component is separated by the turbidity removing device.   In the electrolysis step, acid water is obtained from the anode side, the reverse osmosis membrane is sterilized with the acid water, the acid water after washing, or the acid water directly obtained in the electrolysis step is separated from the precipitate. The method for purifying metal component-containing water according to claim 1 or 2, wherein a neutralization step of neutralizing in addition to the alkaline water from which the metal component has been separated by the step is carried out.   The method for purifying metal component-containing water according to claim 2, wherein the turbidity removing device is a device that turbidizes by filtration using an MF membrane or a UF membrane.   The method for purifying metal component-containing water according to any one of claims 1 to 4, wherein the pH of the alkaline water is 9 to 14. A metal component-containing water purification treatment apparatus having a reverse osmosis membrane separation device that separates metal component-containing water in which a metal component is dissolved into purified water that is permeated water and concentrated water using a reverse osmosis membrane,
Furthermore, an electrolysis apparatus that electrolyzes the concentrated water to obtain alkaline water from the cathode side, and a precipitate separation apparatus that filters and separates metal components deposited by becoming alkaline from the alkaline water obtained by the electrolysis apparatus. A purification apparatus for water containing metal components, comprising:

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