JP2007014902A - Desalination apparatus and washing method of pretreatment membrane of desalination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a desalination apparatus and a washing method of a pretreatment membrane of the desalination apparatus capable of washing the pretreatment membrane without using filtrate. <P>SOLUTION: This desalination apparatus 10A comprises a pretreatment apparatus 13 having the pretreatment membrane 12 filtering turbid components in raw water 11; a reverse osmosis membrane device 17 having a reverse osmosis membrane 16 removing salinity from filtrate 14 supplied from the pretreatment apparatus 13 to obtain fresh water 15; and a back washing line 19 sending concentrated water 18 with concentrated salt from the reverse osmosis membrane device 17 to the pretreatment apparatus 13. The pretreatment membrane 12 is back-washed using the concentrated water 18 as washing water 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a desalination apparatus and a method for cleaning a pretreatment membrane of the desalination apparatus.

  2. Description of the Related Art In long-distance navigation large passenger ships on which remote islands or passengers board, seawater desalination apparatuses that use fresh water (seawater) as fresh water for use as fresh water are used.

Such a desalination apparatus uses a UF membrane (ultrafiltration membrane) or an MF membrane (microfiltration membrane) as a pretreatment technique in order to remove turbid components in seawater that is raw water.
By the way, since it is necessary to remove the collected turbid matter after the membrane has been operated for a predetermined time, conventionally, filtered water filtered through a pretreatment membrane has been used as backwash water (Patent Document 1). .

JP 2001-252536 A

  However, since the filtered water obtained by filtering the raw water is a raw material for fresh water, using a large amount of backwash water reduces the amount of permeated water, resulting in a problem of reduced economic efficiency.

Conventionally, the amount used for backwashing is based on experience, and when external factors such as water quality fluctuate, the operation is carried out using pressure loss as an index.
In order to grasp the optimum backwashing amount, it is necessary to carry out while looking at the operation status.In response to the change of the situation, lag time occurs, and in the worst case, the pretreatment film is blocked. There is a problem that chemical cleaning is forced.

  On the other hand, when operating a UF membrane, there is an example in which cleaning is performed efficiently by putting a small amount of a flocculant on the inlet side. The amount of flocculant is operated using pressure loss etc. as an index, but in order to grasp the optimal backwash amount, it is necessary to perform it while looking at the operating status. There is a problem in that lag time occurs, and in the worst case, the pretreatment film is clogged, and as a result, chemical cleaning is forced.

  This invention makes it a subject to provide the washing | cleaning method of the pretreatment film | membrane of the desalination apparatus and desalination apparatus which can wash | clean a pretreatment film | membrane, without using filtered water in view of the said problem.

  The first invention of the present invention for solving the above-mentioned problem is to remove a salt content from a pretreatment device having a pretreatment membrane for filtering turbid components in raw water and filtered water from the pretreatment device. A reverse osmosis membrane device having a reverse osmosis membrane for obtaining fresh water, and a backwash line for feeding concentrated water enriched with salt from the reverse osmosis membrane device to the pretreatment device, the concentrated water Is used for back cleaning of the pretreatment membrane.

  A second invention is the desalination apparatus according to the first invention, wherein the desalination apparatus comprises a plurality of either or both of the pretreatment device and the reverse osmosis membrane device.

  According to a third aspect of the present invention, there is provided a desalination apparatus according to the first or second aspect of the present invention, further comprising a storage tank that stores the concentrated water from which the salinity is concentrated.

  According to a fourth aspect of the present invention, there is provided a desalination apparatus according to any one of the first to third aspects, further comprising an acid supply unit configured to supply an acid to the backwash line.

  A fifth invention is the desalination apparatus according to any one of the first to fourth inventions, wherein the backwashing line includes a flushing section.

  A sixth invention is the invention according to any one of the first to fifth inventions, wherein a turbidimeter is provided in a discharge line of backwash water discharged from the pretreatment device, and concentrated water according to the turbidity. It exists in the desalination apparatus characterized by adjusting supply_amount | feed_rate.

  According to a seventh aspect of the present invention, when fresh water is obtained using a reverse osmosis membrane after filtering turbid components in raw water with a pretreatment membrane, the concentrated water concentrated by the reverse osmosis membrane is used as a reverse of the pretreatment membrane. The present invention relates to a method for cleaning a pretreatment membrane of a desalinator characterized by being used for cleaning.

  An eighth invention is the fresh water characterized in that, in the seventh invention, the amount of concentrated water used for backwashing is adjusted while measuring the turbidity in the backwashing liquid after backwashing the pretreatment membrane. In the cleaning method of the pretreatment film of the chemical converter.

  According to the present invention, since the concentrated water is used as the washing water for the pretreatment membrane, a part of the filtered water is not used as the backwashing water as in the prior art, and the reduction of the filtered water recovery rate is solved. The whole amount of filtered water can be desalted.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A desalination apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram illustrating a desalination apparatus according to a first embodiment.
As shown in FIG. 1, a desalination apparatus 10 </ b> A according to the present embodiment is supplied from a pretreatment device 13 having a pretreatment membrane 12 that filters turbid components in raw water (raw water) 11, and the pretreatment device 13. A reverse osmosis membrane device 17 having a reverse osmosis membrane (RO membrane) 16 that removes salt from the filtered water 14 to obtain fresh water 15, and a concentrated water 18 in which the salinity from the reverse osmosis membrane device 17 is concentrated. A backwashing line 19 for feeding to the pretreatment device 13 is provided, and the pretreatment film 12 is backwashed using the concentrated water 18 as the washing water 20.
Here, in the figure, reference numeral 21 is a tank for storing the concentrated water 18, 22 is a raw water line for supplying the raw water 11 to the pretreatment device 13, and 23 is a reverse osmosis membrane device 17 from the pretreatment device 13 for the filtered water 14. A filtered water line for supplying water to the tank, 24 for a concentrated water line for supplying the concentrated water 18 to the tank 21, 25 for a fresh water line for supplying fresh water 15 to an external water use facility, etc., and P for a feed pump.

  In the desalination apparatus 10 </ b> A having the above-described configuration, the raw water 11 removes turbid components from the pretreatment membrane 12 of the pretreatment device 13, and the filtrate 14 is supplied to the reverse osmosis membrane device 17 via the filtrate water line 23. Is done. Then, after the salt content is concentrated by the reverse osmosis membrane device 17 to obtain fresh water 15, the fresh water 15 is supplied to an external water use facility (not shown) via the fresh water line 25. The concentrated concentrated water 18 is stored in the tank 21 via the concentrated water line 24. Here, examples of the pretreatment membrane 12 for removing turbid components include a separation membrane such as a UF membrane (ultrafiltration membrane) or an MF membrane (microfiltration membrane), but are not limited thereto. Absent.

  When the pretreatment device 13 is backwashed, after the desalination for a predetermined time, the supply of the raw water 11 is stopped, and the concentrated water 18 from the tank 21 is used as the wash water 20 via the backwash line 19. To the pretreatment device 13 and backwash the pretreatment film 12. And the backwash water 26 containing a suspended matter is sent outside from the backwash water line 27, and performs a predetermined | prescribed process.

  As a result, in the prior art, since a part of the filtered water 14 was used as the washing water, the recovery rate of the filtered water 14 from the pretreatment device 13 was reduced, but according to the present embodiment, the filtered water 14 The total amount of filtered water 14 can be supplied to the reverse osmosis membrane device 17 and converted into fresh water 15, which improves the economic efficiency of the desalination treatment.

  Further, unlike the conventional backwash water, the wash water 20 in the present invention uses the concentrated water 18 discharged from the reverse osmosis membrane device 17, so that the salt concentration is high (the salt concentration is 1 of the raw water). .5 to 2 times), normal marine bacteria will die. Therefore, in the reverse cleaning process of the pretreatment film 12, there is a synergistic effect that the sterilization process can be performed along with the removal of turbidity.

Next, a desalination apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings.
FIG. 2 is a conceptual diagram illustrating a desalination apparatus according to a second embodiment. In addition, about the member same as the desalination apparatus of FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
As shown in FIG. 2, the desalination apparatus 10 </ b> B according to the present embodiment is provided with an acid supply unit 32 that supplies the acid 31 to the backwash line 19 in the desalination apparatus 10 </ b> A of the first embodiment.

As a result, the acid 31 is supplied to neutralize the washing water 20, so that even when the concentrated water 18 having a high salt concentration (salt concentration is 1.5 to 2 times) is used, the backwash line is used. It is possible to prevent the scale inside the pipe 19 from adhering.
The acid 31 to be supplied is supplied with a dilute acid such as hydrochloric acid, sulfuric acid or nitric acid so that the pH becomes 6.

Next, a desalination apparatus according to Embodiment 3 of the present invention will be described with reference to the drawings.
FIG. 3 is a conceptual diagram illustrating a desalination apparatus according to a third embodiment. In addition, about the member same as the desalination apparatus of FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
As shown in FIG. 3, the desalination apparatus 10 </ b> C according to the present embodiment is the same as the desalination apparatus 10 </ b> A according to the first embodiment, except that the flushing line 33 that is a flushing portion is provided in the backwash line 19.

  Thus, by flushing with the flushing line 33 and releasing the concentrated water 18, the propagation of microorganisms in the pipe of the backwash line 19 before backwashing is suppressed.

Next, a desalination apparatus according to Embodiment 4 of the present invention will be described with reference to the drawings.
FIG. 4 is a conceptual diagram illustrating a desalination apparatus according to a fourth embodiment. In addition, about the member same as the desalination apparatus of FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
As shown in FIG. 4, the desalination apparatus 10D according to the present embodiment includes a plurality of pretreatment apparatuses 13 and reverse osmosis membrane apparatuses 17 according to the desalination apparatus 10A of the first embodiment (three in this embodiment). ) Installed.

That is, the desalination apparatus 10D which concerns on a present Example is the pretreatment apparatus 13-1 to 13-3 which has the pretreatment film | membrane 12 which filters the turbid content in raw | natural water 11, and the said pretreatment apparatus 13-1 to 13 -3 from a reverse osmosis membrane device 17-1 to 17-3 having a reverse osmosis membrane 16 for removing salt from filtered water 14 from -3 to obtain fresh water 15, and from the reverse osmosis membrane devices 17-1 to 17-3 Backwashing lines 19-1 to 19-3 for feeding the concentrated water 18 concentrated in salt to the pretreatment devices 13-1 to 13-3, and using the concentrated water 18 as the washing water 20. Thus, the pretreatment film 12 is back-washed.
Here, in this embodiment, on-off valves V1 to V3 are provided to supply the washing water 20 to the backwash lines 19-1 to 19-3, respectively. By opening and closing the on-off valves V1 to V3, washing is performed. Like to do.

  In this embodiment, since a plurality of pretreatment devices and reverse osmosis membrane devices are used, the concentrated water 18 can be secured even when any device is stopped and backwashed. No tank 21 is installed as in FIG.

  In the case of the embodiment shown in FIG. 4, the pretreatment devices 13-1 and 13-3 perform filtration, and fresh water 15 is obtained from the reverse osmosis membrane devices 17-1 and 17-3. V3 is closed. For the pretreatment device 13-2, the supply of the raw water 11 is stopped, and the concentrated water 18 from the reverse osmosis membrane devices 17-1 and 17-3 is used to open the valve V2. By supplying it into the processing device 13-2, the pretreatment film 12 of the pretreatment device 13-2 is back-washed.

  Thereby, the pretreatment film | membrane 12 which filtered raw | natural water 11 for the predetermined time can be wash | cleaned with the washing water 20 by turns. For example, after washing for 1 hour, backwashing is performed for about 5 minutes, so that efficient desalination can always be performed.

  In this embodiment, the number of pretreatment devices and reverse osmosis membrane devices installed is the same. However, the present invention is not limited to this, and the present invention can be applied even when one of them is small.

Next, a desalination apparatus according to Embodiment 5 of the present invention will be described with reference to the drawings.
FIG. 5 is a conceptual diagram illustrating a desalination apparatus according to a fifth embodiment. In addition, about the same member as the desalination apparatus which concerns on FIG. 1 thru | or 4, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
As shown in FIG. 5, the desalination apparatus 10E according to the present embodiment is configured by configuring the pretreatment apparatus 13 according to the desalination apparatus 10A of the first embodiment from a plurality of pretreatment modules 13A to 13C. The filtered water 14 filtered in (1) is desalinated by one reverse osmosis membrane device 17.

  Moreover, the turbidimeters 51-1 to 51-3 are respectively installed in the discharge lines 27-1 to 27-3 of the backwash water 26, and information from these turbidimeters is sent to the control device (CPU) 52. I have to. Based on this information, the amount of cleaning water 20 supplied to the pretreatment membrane 12 is adjusted by adjusting the opening / closing times of the valves V1 to V3.

  In the present embodiment, the concentrated water 18 is used as the washing water 20, and therefore, when the pretreatment membrane 12 is not sufficiently washed, it is sufficient based on the information of the turbidimeters 51-1 to 51-3. Cleaning can be performed. That is, conventionally, even when a turbidimeter is installed, since filtered water was used as washing water, the amount of desalination was reduced, so that sufficient washing could not be performed. According to the above, since the concentrated water is generated in a large amount, when the desired cleaning standard is not satisfied, the cleaning with the concentrated water can be further performed.

  As described above, since the desalination apparatus according to the present invention does not clean the pretreatment membrane using a part of the conventional filtered water, the desalination efficiency is not lowered. It is suitable for use in facilities that desalinate water.

1 is a schematic view of a desalination apparatus according to Embodiment 1. FIG. It is the schematic of the desalination apparatus which concerns on Example 2. FIG. It is the schematic of the desalination apparatus which concerns on Example 3. FIG. It is the schematic of the desalination apparatus which concerns on Example 4. FIG. It is the schematic of the desalination apparatus which concerns on Example 5. FIG.

Explanation of symbols

10A to 10E Desalination equipment 11 Raw water 12 Pretreatment membrane 13 Pretreatment equipment 14 Filtration water 15 Fresh water 16 Reverse osmosis membrane 17 Reverse osmosis membrane equipment 18 Concentrated water 19 Backwash line 20 Washing water 21 Tank

Claims (8)

A pretreatment device having a pretreatment membrane for filtering turbid components in raw water;
A reverse osmosis membrane device having a reverse osmosis membrane that obtains fresh water by removing salt from the filtered water from the pretreatment device;
A backwash line for feeding the concentrated water from which the salt content from the reverse osmosis membrane device is concentrated to the pretreatment device, and using the concentrated water for backwashing the pretreatment membrane. Features a desalination device. In claim 1,
A desalination apparatus comprising a plurality of either or both of the pretreatment apparatus and the reverse osmosis membrane apparatus. In claim 1 or 2,
A desalination apparatus comprising a storage tank for storing concentrated water enriched in salt from the reverse osmosis membrane apparatus. In any one of Claims 1 thru | or 3,
The desalination apparatus characterized by including the acid supply part which supplies an acid to the said backwash line. In any one of Claims 1 thru | or 4,
The desalination apparatus, wherein the backwash line includes a flushing section. In any one of Claims 1 thru | or 5,
A desalination apparatus comprising a turbidimeter in a discharge line of backwash water discharged from the pretreatment apparatus, and adjusting a supply amount of concentrated water according to the turbidity.   When fresh water is obtained using a reverse osmosis membrane after filtering turbidity in raw water with a pretreatment membrane, the concentrated water concentrated by the reverse osmosis membrane is used for back washing of the pretreatment membrane. A method for cleaning a pretreatment membrane of a desalination apparatus. In claim 7,
A method for cleaning a pretreatment membrane of a desalination apparatus, comprising adjusting a supply amount of concentrated water used for backwashing while measuring turbidity in a backwashing liquid after backwashing the pretreatment membrane.

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