JP2012170841A - Compound desalination system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound desalination system that can effectively utilize energy, having a relatively low hydraulic pressure, of non-permeate of a reverse osmosis membrane device in the compound desalination system.SOLUTION: The compound desalination system 100A includes a seawater desalination treatment system 3 that filters seawater D using a seawater reverse osmosis membrane device 38, and a wastewater treatment system 1 that filters wastewater A having a lower salt concentration than the seawater D using a low-pressure reverse osmosis membrane device 16. In the seawater desalination treatment system 3, fine foams are generated in and released from a fine foam generating part 19 in an intake chamber 32 that stores taken-in seawater D, by decompressing non-permeate C discharged from the low-pressure reverse osmosis membrane device 16 of the wastewater treatment system 1.

Description

  The present invention provides a first water treatment system for filtering a first raw water having a high salinity concentration, such as seawater, brackish water, brine, etc., using a reverse osmosis membrane device, and a first salt treatment having a lower salinity concentration than the first raw water. And a second water treatment system for filtering the raw water of No. 2 using a reverse osmosis membrane device, and in particular, a non-permeate discharged from the reverse osmosis membrane device of the second water treatment system The present invention relates to a technique for improving the operating rate of a first water treatment system by utilizing the hydraulic energy of water.

  In Patent Document 1, in a seawater desalination apparatus that desalinates seawater by filtration using a reverse osmosis membrane apparatus, for example, wastewater containing organic substances represented by sewage (hereinafter referred to as “organic wastewater”) is disclosed. Normally, biological wastewater that has been biologically treated and discharged into the ocean or river is mixed with seawater taken by the seawater desalination unit, and the salinity of the treated water in the seawater desalination unit is mixed. By reducing (diluting) the seawater as it is, and feeding the treated water diluted with the above-mentioned salinity to the reverse osmosis membrane device of the seawater desalination unit, the pumping pump (in the “high pressure pump” in this specification) The technology for reducing the required driving force is described.

Patent Document 2 describes a technique for generating microbubbles by pumping air dissolved in water and reducing the pressure.
By the way, in water treatment, micro bubbles such as micro bubbles and nano bubbles are generated in the water to be treated, and the micro bubbles stay in the water to be treated for a relatively long time. It is a well-known technique that the organic matter can be decomposed.

  Furthermore, Patent Document 3 describes a technique for injecting ozone gas into the water to be treated for sterilization.

Japanese Patent No. 4,481,345 JP 2010-274243 A JP 09-290260 A

However, in the technique described in Patent Document 1, the pressure when the reverse osmosis membrane device is used in the water treatment process of organic wastewater is higher than the pressure when the reverse osmosis membrane device is used in the water treatment process of the seawater desalination device. Low pressure. And, the non-permeated water discharged from the reverse osmosis membrane device in the water treatment process of the organic wastewater is only mixed with the seawater taken directly, and the salinity concentration is lowered than the seawater. Since the energy of the non-permeated water from the reverse osmosis membrane device in the wastewater treatment process is relatively low pressure, it is not used at all and is wasted.
Moreover, since organic matter in the water to be treated is increased by using organic wastewater for dilution of seawater, there is a problem that the frequency of fouling of the reverse osmosis membrane in the seawater desalination apparatus increases.

  The present invention solves the above-described conventional problems, and can effectively use the energy of non-permeated water of a reverse osmosis membrane device in a complex desalination system and can reduce the frequency of fouling. The purpose is to provide a desalination system.

  In order to solve the above-mentioned problems, a combined desalination system of the present invention includes a first water treatment system for filtering a first raw water having a high salinity using a first reverse osmosis membrane device, A second water treatment system for filtering the second raw water having a salt concentration lower than that of the raw water using the second reverse osmosis membrane device, and in the first water treatment system, Fine bubble generating means for generating and releasing fine bubbles by reducing the pressure of non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system in the taken first raw water is provided. It is characterized by that.

The fine bubble generating means includes a first pipe connecting an outlet of non-permeated water of the second reverse osmosis membrane device and a first raw water tank for storing the taken first raw water, A first valve provided on the first raw water tank side of the first pipe and a first valve provided on the downstream side of the first valve of the first pipe, the first permeate of the second reverse osmosis membrane device It is preferable to include a fine bubble generating unit that rapidly decompresses the raw water tank to generate and discharge the gas dissolved therein as the fine bubbles.
The fine bubble generating means is further provided in a second pipe branched from the first pipe at a position upstream of the first valve and connected to the first raw water tank, and a second pipe. And a second valve for adjusting the flow rate of the non-permeate water of the reverse osmosis membrane device.

  Furthermore, it is preferable to provide an ozone generator for generating ozone gas, and to provide an ozone injection section for injecting ozone gas generated by the ozone generator in the first pipe between the first valve and the fine bubble generation section.

  Conventionally, in order to generate fine bubbles, separate power has been required to compress and blow in air or to rapidly reduce pressure to generate dissolved gas as fine bubbles. On the other hand, according to the present invention, fine bubbles can be sufficiently generated by decompression even at a relatively low pressure of nonpermeate water discharged from the second reverse osmosis membrane device of the second water treatment system. Therefore, it is possible to save the electric power required for the operation of the composite desalination system without requiring new power for generating fine bubbles.

  Moreover, it is discharged from the second reverse osmosis membrane device of the second water treatment system only by flowing the entire amount of non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system to the fine bubble generating unit. There is a possibility that the flow rate of non-permeated water to be adjusted cannot be adjusted. In contrast, in the present invention, the second reverse osmosis is provided in the second pipe branched from the first pipe at a position upstream of the first valve and connected to the first raw water tank, and the second pipe. By including the second valve for adjusting the flow rate of the non-permeate water of the membrane device, the flow rate of the non-permeate water of the second reverse osmosis membrane device can also be adjusted.

  Furthermore, in the present invention, an ozone generator that generates ozone gas is provided, and an ozone injection unit that injects ozone gas generated by the ozone generator is provided in a first pipe between the first valve and the fine bubble generator. In this way, fine bubbles containing ozone gas can be generated in the fine bubble generating part, and not only the decomposition of organic matter due to shock waves generated in the process of crushing the fine bubbles with respect to the treated water containing the first raw water, A bactericidal effect by ozone can also be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the composite desalination system which can utilize effectively the energy of the non-permeated water of the reverse osmosis membrane apparatus in a composite desalination system can be provided.

It is a schematic block diagram of the composite desalination system of basic embodiment. It is a schematic block diagram of the composite desalination system which concerns on 1st Embodiment. FIG. 3 is an enlarged explanatory view of a part X in FIG. 2, and is an explanatory view of a combined desalination system according to a second embodiment in which an ozone generator and an ozone injection pump are further combined with the combined desalination system according to the first embodiment. is there. FIG. 3 is an enlarged explanatory view of a portion X in FIG. 2, including a combined desalination system according to a third embodiment in which a reaction tank is combined with the combined desalination system according to the first embodiment, an ozone generator, and an ozone injection pump. It is explanatory drawing of the composite desalination system which concerns on 4th Embodiment combined.

  Below, the composite desalination system which concerns on embodiment of this invention is demonstrated in detail, referring a figure.

<< Compound desalination system of basic embodiment >>
First, a combined desalination system 100 according to a basic embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram of the composite desalination system of the basic embodiment.
This composite desalination system 100 is assumed to be installed in a coastal zone, in the vicinity of a saltwater lake, in the vicinity of a brackish water zone, and the like.
The combined desalination system 100 is a wastewater (second raw water) A (hereinafter simply referred to as “drainage A”) having a lower salinity than seawater, brackish water, brine, and the like, such as industrial wastewater and urban wastewater. A wastewater treatment system (second water treatment system) 1 for wastewater treatment so that it can be reused as middle water other than drinking water such as industrial water (referred to as “permeate water B” or “product water B”); Reuse water (first raw water) D with relatively high salinity, such as seawater, brackish water, brine, etc., as medium water (referred to as “permeate E” or “product water E”) other than drinking water such as industrial water A seawater desalination treatment system (first water treatment system) 3 that performs purification treatment as possible, and a control device 6 that controls the operation of pumps and valves included in the wastewater treatment system 1 and the seawater desalination treatment system 3. It is configured.
In the following, “water D having a relatively high salinity such as seawater, brackish water, brine, etc.” is hereinafter referred to as “seawater D” as representatively and as described above in the meaning of “seawater D”. This is referred to as “seawater desalination treatment system 3”.

(Configuration of wastewater treatment system 1)
First, a schematic configuration of the wastewater treatment system 1 will be described with reference to FIG. The drainage A contains organic substances and is referred to as a water treatment device (hereinafter referred to as “MBR water treatment device 11”) using, for example, a membrane separation activated sludge method (MBR) from the drainage water intake pipe 51. Simply “MBR”) and primary processing. The treated water primarily treated in the MBR water treatment apparatus 11 is once introduced from the MBR water treatment apparatus 11 to the treated water tank 13 serving as a buffer for the flow of the treated water through the pipe 52 by the transfer pump 12. It is stored. Further, the water to be treated stored in the treated water tank 13 is sucked by the supply pump 14 through the pipe 53 and supplied to the high pressure pump 15, and the pressure is increased by the high pressure pump 15. The reverse osmosis membrane device) 16 is supplied to the supply port 16a of the water to be treated.

The low-pressure reverse osmosis membrane device 16 has a configuration in which, for example, a plurality of membrane module units as described in FIGS. 3 and 4 of JP 2001-149932 A are arranged in parallel.
The treated water supplied with pressure from the supply port 16a passes through the reverse osmosis membrane (RO membrane: Reverse Osmosis Membrane) in the low-pressure reverse osmosis membrane device 16 and purified water. It is separated into non-permeated water C which is treated water that has not permeated the membrane. The permeated water B is supplied from the permeation port 16b through the pipe 54 to the use according to the external water quality level as the produced water B.

The flow rate of the non-permeated water C is adjusted by a back pressure valve 18 provided in the middle from the drain port (the non-permeated water outlet of the second reverse osmosis membrane device) 16c of the low pressure reverse osmosis membrane device 16 through the pipe 56. Then, it is supplied to a water intake tank (first raw water tank) 32 to be described later. The TDS (Total Dissolubed Solids) of the concentrated non-permeated water C of the wastewater treatment system 1 is about 1,200 mg / liter, and the TDS of seawater D is about 30,000 mg / liter. Therefore, the concentration is extremely low. Therefore, the low-pressure reverse osmosis membrane device 16 described above is operated at a pressure of 0.8 to 1.5 MPa. Incidentally, the range of the operating pressure is to increase the operating pressure in order to obtain the required flow rate of the permeated water B when the contamination of the reverse osmosis membrane of the low pressure reverse osmosis membrane device 16 increases.
Therefore, the pressure of the non-permeate water C is about 0.8 to 1.5 MPa. Then, this pressure is released by the back pressure valve 18 described above.
An ultrafiltration device may be used instead of the MBR water treatment device 11 of the wastewater treatment system 1.
The pipe 56 on the downstream side of the back pressure valve 18 may be configured to generate fine bubbles at the stage of introducing the non-permeated water C of the low pressure reverse osmosis membrane device 16 into the water intake tank. The embodiments will be described in detail in the fourth to fourth embodiments.

(Seawater desalination treatment system 3)
Next, a schematic configuration of the seawater desalination treatment system 3 will be described with reference to FIG. Seawater D is sucked from the water intake pipe 81 by the water intake pump 31, supplied to the water intake tank 32 by the water intake pipe 82, and stored. As described above, since the non-permeate water C of the wastewater treatment system 1 is supplied to the water intake tank 32 through the pipe 56, the seawater D and the non-permeate water C are mixed in the water intake tank 32, and the salt concentration is lower than seawater. It becomes treated water. That is, the value of TDS is also lower than that of seawater D.
The treated water collected in the water intake tank 32 is supplied with a predetermined pressure to the pretreatment filtration device 34 by the filtration pump 33 through the pipe 83.
Examples of the pretreatment filtration device 34 include a UF device using an ultrafiltration membrane (UF (Ultra Filtration) membrane), an MF device using a microfiltration membrane (MF (Micro Filtration) membrane), and a sand filtration device. Either is fine. Incidentally, in FIG. 1, “UF” representing a UF device is typically displayed on the pretreatment filtration device 34.
When a UF device is taken as an example of the pretreatment filtration device 34, it is generally operated at 50 to 150 kPa.

The treated water filtered by the pretreatment filtration device 34 is temporarily stored in the treated water tank 35 serving as a buffer for the flow of the treated water through the pipe 84. Then, the water to be treated stored in the treated water tank 35 is sucked by the supply pump 36 through the pipe 85 and supplied to the high pressure pump 37, and the pressure is increased to, for example, about 3.5 to 6 MPa by the high pressure pump 37. The seawater reverse osmosis membrane device (first reverse osmosis membrane device) 38 is supplied to the supply port 38a of the water to be treated. The seawater reverse osmosis membrane device 38 has, for example, a configuration in which a plurality of membrane module units as described in FIGS. 3 and 4 of JP-A-2001-149932 are arranged in parallel. However, since it is operated at a higher pressure than the low-pressure reverse osmosis membrane device 16, the material of the reverse osmosis membrane of the seawater reverse osmosis membrane device 38 has a performance capable of withstanding a higher pressure.
By the way, this operating pressure is obtained in order to obtain the required flow rate of the permeated water E when the TDS value of the treated water supplied to the reverse osmosis membrane of the seawater reverse osmosis membrane device 38 and the contamination increase. Increase.

  The treated water supplied with pressure from the supply port 38a is the permeated water E that has been purified by permeating the reverse osmosis membrane in the seawater reverse osmosis membrane device 38, and the treated water that has not permeated the reverse osmosis membrane. It is separated into non-permeated water G which is water. The permeated water E is supplied from the permeate port 38b through the pipe 87 to the use according to the external water quality level as the produced water E.

The non-permeated water G has the operating pressure of the seawater reverse osmosis membrane device 38 and is supplied from the drain port 38c to the high pressure supply port 39d of the pressurization side end portion 39b described later in the energy recovery device 39 through the pipe 89. After the pressure is directly exchanged with the water to be treated supplied from the supply pump 36, the flow rate is adjusted by the back pressure valve 40 provided in the middle of the pipe 90 from the discharge port 39e of the pressurization side end portion 39b and discharged. The
This non-permeated water G is seawater, brackish water, or brackish water in which salinity is concentrated.
In this basic embodiment, the energy recovery device 39 is of a direct pressure exchange type, and is mainly a rotor portion 39a, a pressure side end portion 39b, and a pressure side to be rotated at a predetermined rotational speed by a motor (not shown). This is an apparatus of a known technique that is configured by an end portion 39c.

  A pipe 91 is branched from the pipe 85 at a branch point P1 of the pipe 85 between the supply pump 36 and the high-pressure pump 37, and a part of the low-pressure treated water supplied by the supply pump 36 is added to the energy recovery device 39. It is supplied to the supply port 39g of the compression side end portion 39c. And the to-be-processed water supplied to the supply port 39g is pressurized by the direct exchange of the pressure with the non-permeated water G from the seawater reverse osmosis membrane apparatus 38, Then, from the discharge port 39f of the to-be-pressurized side end part 39c It is further supplied to a booster pump 41 provided in the middle of the pipe 92. The booster pump 41 boosts the water to be treated which has been pressurized by the energy recovery device 39 to the same pressure as the high pressure pump 37, and is supplied from the high pressure pump 37 at the junction P <b> 2 of the pipe 86 on the downstream side of the high pressure pump 37. The treated water and the treated water from the pipe 92 are merged and supplied to the supply port 38a of the seawater reverse osmosis membrane device 38.

  Thus, since the non-permeated water G of the seawater reverse osmosis membrane device 38 has an extremely high pressure, the energy is recovered and reused as energy for supplying the water to be treated to the seawater reverse osmosis membrane device 38. However, the power cost can be saved by reducing the capacity of the high-pressure pump 37. Moreover, the salt concentration can be reduced by mixing the non-permeated water C of the waste water treatment system 1 with the seawater D, and the pressure increase required for the high-pressure pump 37 is about 6 MPa in the case of only seawater. When the non-permeated water C and the seawater D are made substantially the same amount and diluted, it can be lowered to about 3.5 MPa. As a result, the power cost can be reduced accordingly. That is, the operating pressure of the seawater reverse osmosis membrane device 38 is higher than the operating pressure of the low pressure reverse osmosis membrane device 16, and the energy of the non-permeated water G of the seawater reverse osmosis membrane device 38 is recovered and the seawater reverse osmosis is recovered. The operating pressure itself of the membrane device 38 can also be reduced.

  The transfer pump 12, the supply pump 14, the high pressure pump 15, the intake pump 31, the filtration pump 33, the supply pump 36, the high pressure pump 37, the booster pump 41, the rotor 39a of the energy recovery device 39, and the like are not shown. An inverter device (not shown) that is connected to the rotating shaft of the motor and is configured integrally and supplies power to the drive motor is installed as a field board or is integrally attached to the drive motor. And the control apparatus 6 is a structure which controls rotation of a drive motor via an inverter.

(Control device 6)
Next, an outline of the control of the control device 6 in the basic embodiment will be described.
The control device 6 is composed of, for example, a plurality of control units 60, 61, 63, and each of the control units 60, 61, 63 has a CPU board, an input / output interface board, and the like on which a CPU, ROM, RAM, etc., not shown are mounted. It is equipped with. The control unit 60 controls the entire composite desalination system 100, the control unit 61 controls the wastewater treatment system 1, and the control unit 63 controls the seawater desalination treatment system 3. Therefore, the control unit 60 is connected to the control units 61 and 63 so as to communicate with each other.
And the control unit 61 contains the flow volume control part (not shown) which adjusts the opening degree of the back pressure valve 18 as a function part, and adjusts the flow volume of the non-permeate water C. FIG.

  The required flow rate commands C1 and C2 of the production water B and the production water E in the combined desalination system 100 are input to the control unit 60 of the control device 6 from the outside. Then, the control unit 60, for example, according to the required flow rate command C1, the waste water flow rate supplied to the waste water treatment system 1 (flow rate detected by the flow rate sensor S1 described later) and the flow rate of the permeate B (flow rate described later). Based on the flow rate detected by the sensor S6), the target flow rate of the permeated water B of the wastewater treatment system 1 is set to cause the control unit 61 to control the wastewater treatment system 1, and in accordance with the required flow rate command C2, seawater A target flow rate of the permeated water E of the desalination treatment system 3 is calculated, and the control unit 63 controls the seawater desalination treatment system 3.

  For this purpose, the drainage intake pipe 51 is provided with a flow rate sensor S1 for detecting the flow rate of the drainage A, and the pipe 54 is provided with a flow rate sensor S6 for detecting the flow rate of the permeated water B. The flow rate and the flow rate of the permeated water B are input to the control unit 60. The pipe 87 is provided with a flow rate sensor S20 that detects the flow rate of the permeated water E, and the flow rate of the permeated water E is input to the control unit 60 via the control unit 63.

  For example, the MBR water treatment apparatus 11 is provided with a water level sensor S2, and the control unit 61 controls the start and stop of the transfer pump 12 based on the water level signal from the water level sensor S2. The treated water tank 13 is provided with, for example, a water level sensor S3, and the control unit 61 receives the water level signal from the water level sensor S3 and the pressure signal from the pressure sensor S4 provided in the pipe 53 on the suction side of the high-pressure pump 15. Based on this, the start and stop control of the supply pump 14 and the rotation speed during operation of the supply pump 14 are controlled. The control of the rotation speed of the supply pump 14 based on the pressure signal from the pressure sensor S4 is for giving a predetermined suction pressure to the high-pressure pump 15.

Further, the control unit 61 has a high pressure so that the flow rate becomes the target flow rate of the permeated water B input from the control unit 60 based on the flow rate signal of the permeated water B from the flow rate sensor S6 provided in the pipe 54. The rotational speed of the pump 15 is adjusted. Then, the rotational speed of the high-pressure pump 15 is feedback-controlled so that the flow rate signal becomes constant based on the flow rate signal from the flow rate sensor S5 provided in the piping 53 on the discharge side of the high-pressure pump 15 at that time.
The feedback control of the rotational speed of the high-pressure pump 15 in the control unit 61 is appropriately corrected based on the deviation between the flow rate signal of the permeated water B and the target flow rate of the permeated water B.

  The pipe 56 is provided with a flow rate sensor S7 for detecting the flow rate of the non-permeate water C of the low-pressure reverse osmosis membrane device 16, and the flow rate control unit of the control unit 61 controls the flow rate of the non-permeate water C. The opening degree of the back pressure valve 18 is adjusted based on the flow rate signal from the flow rate sensor S7 so that the flow rate becomes a constant rate with respect to the flow rate indicated by the water flow rate sensor S5.

The intake pipe 82 is provided with a flow rate sensor S11, and the intake tank 32 is provided with a water level sensor S12. The control unit 63 controls the start and stop of the water intake pump 31 based on the water level signal from the water level sensor S12, and the seawater D according to the flow rate of the non-permeated water C discharged from the waste water treatment system 1 to the water intake tank 32. Is set, and the rotational speed of the water intake pump 31 is controlled based on the flow rate signal from the flow rate sensor S11.
For example, when the flow rate of the non-permeate water C and the intake flow rate of the seawater D are substantially the same, and the non-permeate water C is mixed with the seawater D in the intake tank 32 to reduce the salinity, the seawater reverse osmosis membrane device 38 The operating pressure can be maintained at about 3.5 to 4 MPa, for example.

  The control unit 63 controls the start and stop of the filtration pump 33 based on the water level signal from the water level sensor S14 provided in the treated water tank 35, and the flow rate signal from the flow rate sensor S13 provided in the pipe 84. Based on the above, the rotational speed of the filtration pump 33 is controlled to a predetermined rotational speed, the water to be treated in the water intake tank 32 is pumped to the pretreatment filtration device 34 at a predetermined pressure, subjected to a primary treatment, and the treated water subjected to the primary treatment Is stored in the treated water tank 35.

  Further, the control unit 63 controls the start and stop of the supply pump 36 based on the pressure signal from the pressure sensor S15 provided in the suction-side pipe 85 of the high-pressure pump 37, and the rotation speed during operation of the supply pump 36. To control. The control of the rotation speed of the supply pump 36 based on the pressure signal from the pressure sensor S15 is to give a predetermined suction pressure to the high-pressure pump 37.

Further, the control unit 63 supplies the flow rate of the permeated water E input from the control unit 60 based on the flow rate signal of the permeated water E from the flow rate sensor S20 provided in the pipe 87. The rotational speeds of the pump 36, the high pressure pump 37, and the booster pump 41 are adjusted. Then, the rotational speeds of the high pressure pump 37 and the booster pump 41 so that the flow rate signals are constant based on the flow rate signal from the flow rate sensor S16 provided in the piping 86 on the discharge side of the high pressure pump 37 and the booster pump 41 at that time. Feedback control.
Note that the feedback control of the rotational speeds of the high-pressure pump 37 and the booster pump 41 in the control unit 63 is corrected as appropriate based on the deviation between the flow rate signal of the permeate E and the target flow rate of the permeate E.

  The pipe 89 is provided with a flow rate sensor S19 for detecting the flow rate of the non-permeate water G of the seawater reverse osmosis membrane device 38, and the control unit 63 determines that the flow rate of the non-permeate water G is the flow rate sensor S16 of the water to be treated. The opening degree of the back pressure valve 40 is adjusted so that the amount of water is a constant ratio with respect to the indicated flow rate.

  Thus, in the composite desalination system 100 of the basic embodiment, the non-permeated water C of the low-pressure reverse osmosis membrane device 16 discharged from the waste water treatment system 1 is mixed with the seawater D that has been taken in, and the seawater desalination treatment system 3 By using the water to be treated, the salinity of the water to be treated in the seawater desalination treatment system 3 can be reduced to about half, and the operating pressure for operating the seawater reverse osmosis membrane device 38 is treated only with 100% seawater. The pressure can be greatly reduced as compared with about 6 MPa required in some cases, and the power cost can be reduced.

<< First Embodiment >>
Next, the composite desalination system 100A according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic block diagram of the composite desalination system according to the first embodiment. The basic configuration of the composite desalination system 100A of the present embodiment is substantially the same as the composite desalination system 100 of the basic embodiment shown in FIG. 1, but the composite desalination system 100 is the function of the control device 6. 2 and at the branch point P5 on the intake tank 32 side of the pipe 56 as shown in the X part of FIG. 2, the pipe 56 to the pipe 57 (first pipe) and the pipe 58 (second pipe) ), The pipe 57 is provided with a pressure reducing valve (first valve) 17, and the pipe 57 on the downstream side thereof is provided with a pressure sensor (fine bubble generation pressure detecting means) S9. The difference is that the fine bubble generating unit 19 is provided at the outlet located below the water surface in the water intake tank 32. Incidentally, a back pressure valve (second valve) 18 is provided in the pipe 58.
The micro-bubble generating unit 19 generates gas dissolved in the non-permeated water C as micro-bubbles 105 having the size of microbubbles or nanobubbles by rapidly depressurizing the non-permeated water C from a predetermined pressure. Released into the water to be treated.

  Here, the pipes 57 and 58, the pressure reducing valve 17, the back pressure valve 18, and the fine bubble generating unit 19 correspond to “fine bubble generating means” described in the claims.

The functions of the control units 60 and 63 of the control device 6 in the present embodiment are the same as the functions of the control units 60 and 63 of the control device 6 in the composite desalination system 100 of the basic embodiment. The function of the control unit 61 of the control device 6 in the present embodiment is substantially the same as the function of the control unit 61 of the control device 6 in the combined desalination system 100, but a flow rate control unit (not shown) as its function unit. However, the difference is that the opening degree of the back pressure valve 18 is adjusted to adjust the flow rate of the non-permeated water C, and the fine bubble generating unit 19 has a control function for generating fine bubbles.
The same components as those of the composite desalination system 100 are denoted by the same reference numerals and redundant description is omitted, and redundant description of the same control function in the control device 6 of the basic embodiment is also omitted.

  The flow rate control unit as the above-described functional unit of the control unit 61 in the present embodiment adjusts the opening of the pressure reducing valve 17 based on the pressure signal from the pressure sensor S9, and a pressure suitable for generation of the fine bubbles 105, for example, Then, after reducing the pressure to 0.5 MPa, the non-permeated water C is supplied to the fine bubble generating unit 19. In addition, the above-described flow rate control unit of the control unit 61 includes the flow rate sensor (flow rate detection means) S7 so that the flow rate of the non-permeated water C is a constant rate relative to the flow rate indicated by the flow rate sensor S5. The opening degree of the back pressure valve 18 is adjusted based on the flow signal.

According to the present embodiment, the seawater desalination treatment system 3 uses a UF membrane device, an MF membrane device or a sand filtration device as the pretreatment filtration device 34 as a pretreatment of the seawater reverse osmosis membrane device 38. D, the organic matter contained in the non-permeate water C can be treated and removed.
In particular, since the non-permeated water C contains more than double the amount of organic matter in the seawater D, it can be removed efficiently. In addition, a large amount of microorganisms and organic substances may flow into the taken seawater D depending on the sea area and season, and the seawater D usually contains organic substances metabolized by microorganisms.

Then, the opening degree of the pressure reducing valve 17 is adjusted by the flow rate control unit of the control unit 61, and the pressure of 0.8 to 1.5 MPa of the non-permeated water C in the water intake tank 32 is changed to the fine bubble generating unit 19. By reducing the pressure to a required pressure capable of generating the fine bubbles 105, for example, 0.5 MPa, the non-permeated water C containing the fine bubbles 105 is released into the water intake tank 32 without requiring any power. be able to.
Further, since the pressure of the non-permeate water C changes depending on the operating pressure of the low-pressure reverse osmosis membrane device 16, all the predetermined flow rate of the non-permeate water C passes through the pipe 57 only by adjusting the opening of the pressure reducing valve 17. Therefore, when the operating pressure of the low-pressure reverse osmosis membrane device 16 is high, the flow rate control unit of the control unit 61 has a non-flow rate indicated by the flow rate sensor S7. The opening degree of the back pressure valve 18 is feedback-controlled so as to coincide with the target flow rate of the permeate C. As a result, the generation control of the fine bubbles 105 in the flow rate control unit of the control unit 61 does not disturb the processing amount of the wastewater treatment system 1.

Furthermore, by releasing the fine bubbles 105, that is, microbubbles or nanobubbles, from the fine bubble generation unit 19 into the intake tank 32, the organic matter in the intake tank 32 can be decomposed by a shock wave generated when the fine bubbles 105 are crushed. In addition, since radicals are generated to promote the decomposition of organic substances, the pretreatment filtration device 34 is less clogged, and the amount of water to be treated that can be treated up to that required for backwashing is increased. That is, it is possible to lengthen the time required for backwashing the pretreatment filtration device 34 for the treatment of the water to be treated at a constant flow rate, and to improve the operating rate of the composite desalination system 100A.
Moreover, although the organic matter in to-be-processed water increases by using the waste water A which is organic waste water for dilution of the seawater D, since the organic matter is decomposed by the fine bubbles 105, the seawater reverse osmosis membrane of the seawater desalination system 3 The frequency of reverse osmosis membrane fouling in the device 38 can be reduced.

<< Second Embodiment >>
Next, the composite desalination system 100B which concerns on 2nd Embodiment is demonstrated, referring FIG. 2, FIG. FIG. 3 is an enlarged explanatory view of a portion X in FIG. 2, and the combined desalination system according to the second embodiment in which an ozone generator and an ozone injection pump are further combined with the combined desalination system according to the first embodiment. It is explanatory drawing of.
The composite desalination system 100B of the second embodiment is different from the composite desalination system 100A of the first embodiment in that the portion X shown in FIG. 2 further includes an ozone generator 45, ozone, as shown in FIG. An injection pump 46 is provided, and ozone gas generated by the ozone generator 45 is introduced into the non-permeated water C that has been reduced to the predetermined pressure by the pressure reducing valve 17 from the injection part P11 provided in the pipe 57 by the ozone injection pump 46. The point is to inject and melt.
And in the control apparatus 6 in 2nd Embodiment, the function which controls the ozone generator 45 and the ozone injection pump 46 in the control unit 63 of the control apparatus 6 in 1st Embodiment is added.

The point that the function of the control unit 63 in the second embodiment is different from the function of the control unit 63 in the first embodiment is that the function unit of the control unit 63 in the composite desalination system 100 of the basic embodiment is newly It is only the point comprised including the ozone injection | pouring control part (not shown).
The above-described ozone injection control unit of the control unit 63 controls the ozone generator 45 so as to generate ozone gas corresponding to the target flow rate of the non-permeated water C, and the ozone injection pump 46 according to the amount of generated ozone gas. The rotation speed is controlled to be injected from the injection part P11.

  According to this embodiment, since the microbubble 105 contains ozone, there exists an effect which sterilizes the to-be-processed water in the water intake tank 32. FIG.

<< Third and Fourth Embodiments >>
Next, composite desalination systems 100C and 100D according to the third and fourth embodiments will be described with reference to FIGS. FIG. 4 is an enlarged explanatory view of a portion X in FIG. 2, and the combined desalination system according to the third embodiment in which a reaction tank is combined with the combined desalination system according to the first embodiment, an ozone generator, and It is explanatory drawing of the composite desalination system which concerns on 4th Embodiment which combined the ozone injection pump.
(Third embodiment)
First, the composite desalination system 100C which concerns on 3rd Embodiment is demonstrated. The composite desalination system 100C of the third embodiment is different from the composite desalination system 100A of the first embodiment in that the part X shown in FIG. 2 reacts to the front stage of the water intake tank 32 as shown in FIG. A tank (first raw water tank) 47 is installed, and in the first compartment 47 c ₁ of the reaction tank 47, the fine bubble generating part 19 at the outlet part of the intake pipe 57 and the outlet of the pipe 58 are provided as in the first embodiment. It is a point to install. The outlet 96 of the reaction tank 47 communicates with the water intake tank 32 as it is.
And as the control apparatus 6 in this embodiment, the control apparatus 6 in 1st Embodiment is used.
In the present embodiment, the reaction tank 47 corresponds to the “first raw water tank” described in the claims.

The reaction tank 47 is divided into a plurality of compartments (partition compartments) 47C ₁ , 47C ₂ , 47C ₃ , 47C ₄ by a plurality of partition plates 47a and 47b. The partition plate 47a has a communication path between the bottom of the reaction tank 47, and the partition plate 47b is configured such that the lower part is connected to the bottom of the reaction tank 47 and the treated water passes over the upper part and communicates. ing. The partition plates 47a and 47b are configured such that the water to be treated is alternately changed in the vertical direction as indicated by the arrow Y in the flow direction. The water to be treated flows from the last compartment 47C ₄ aquarium 32 collected via an outlet 96 as indicated by arrow Z.

  By providing the reaction tank 47 in the preceding stage of the water tank 32 in this way, the mixing of the water to be treated and the fine bubbles 105 is promoted, and the decomposition of the organic matter by the fine bubbles 105 is promoted.

(Fourth embodiment)
Next, the composite desalination system 100D which concerns on 4th Embodiment is demonstrated. The composite desalination system 100D of the fourth embodiment adds an ozone generator 45 and an ozone injection pump 46 indicated by broken lines in FIG. 4 to the composite desalination system 100C of the third embodiment, and the second embodiment. Is controlled by the above-described ozone injection control unit of the control unit 63 of the control device 6.
In the present embodiment, the reaction tank 47 corresponds to the “first raw water tank” described in the claims.

According to this embodiment, mixing of the ozone gas and the water to be treated in the reaction tank 47 is promoted, and the sterilizing effect of the water to be treated is enhanced as compared with the case of the second embodiment.
In the present embodiment, surplus ozone gas may be released from the surface of the water to be treated and released into the atmosphere. It is desirable to release it into the atmosphere after treatment.

As described above, according to the first to fourth embodiments, the relatively low pressure of 0.8 to 1.5 MPa that the non-permeated water C of the wastewater treatment system 1 has is used as energy generated by the fine bubbles 105. Because it is used, conventional water to be treated is pressurized with a motor pump and then suddenly decompressed to generate fine bubbles, or air is pressurized and discharged from the fine holes into the treated water to generate fine bubbles. Thus, the composite desalination systems 100A to 100D can be provided that do not require power as in the case of causing them to be reduced and reduce the power cost.
Moreover, the composite desalination system 100A-100D with the improved operation rate which can reduce the fouling frequency of the reverse osmosis membrane in the seawater reverse osmosis membrane apparatus 38 of the seawater desalination processing system 3 can be provided.

In the first to fourth embodiments, the direct pressure exchange type is described as the energy recovery device 39 in FIG. 2 and the booster pump 41 is combined in the subsequent stage, but the invention is not limited thereto. . The turbocharger pump may be driven by non-permeate water G. In this case, the pipe 89 and the pipe 90 are connected to the turbine part (drive part) inlet and outlet of the turbocharger pump, respectively, and the downstream side of the pipe 86 is connected to the pump part inlet of the turbocharger pump. Is connected to the supply port 38a by piping. Even in such a format, the pressure of the non-permeated water G can be recovered.
Incidentally, in that case, the pipes 91 and 92 and the booster pump 41 are unnecessary.

Moreover, although the example which provides the fine bubble generation part 19 in the water intake tank 32 was demonstrated in the 1st-4th embodiment, the fine bubble generation part 19 was provided in the middle of the piping 57 of the downstream of the pressure-reduction valve 17. Fine bubbles 105 may be generated.
Further, a confluence of the pipe 82 and the pipe 57 is provided, and a fine bubble generating unit 19 is provided at a portion where the non-permeated water C of the low pressure reverse osmosis device 16 is mixed with the seawater D to generate the fine bubbles 105, and thereafter You may make it store the to-be-processed water with which the seawater D containing the fine bubble 105 and the non-permeated water C of the low pressure reverse osmosis apparatus 16 were mixed in the water tank 32. FIG.
Alternatively, only the seawater D is introduced and stored in the intake tank 32, and a confluence point with the pipe 57 is provided on the upstream side of the filtration pump 33 of the pipe 83, so that the non-permeate water C of the low pressure reverse osmosis device 16 is the seawater D. The fine bubble generation unit 19 may be provided at the confluence point to be mixed to generate the fine bubble 105.

  In the basic embodiment and the first to fourth embodiments described above, the production water B and the production water E are supplied to the outside according to the respective water quality levels, but the production water B and the production water E are mixed. Then, it may be supplied to the outside.

1 Wastewater treatment system (second water treatment system)
3 Seawater desalination treatment system (first water treatment system)
6 Control device 11 MBR water treatment device 12 Transfer pump 13 Treated water tank 14 Supply pump 15 High pressure pump 16 Low pressure reverse osmosis membrane device (second reverse osmosis membrane device)
16c Drainage port (outlet of non-permeated water of the second reverse osmosis membrane device)
17 Pressure reducing valve (first valve, fine bubble generating means)
18 Back pressure valve (second valve, means for generating fine bubbles)
19 Microbubble generator (microbubble generator)
31 Intake pump 32 Intake tank (first raw water tank)
33 Filtration pump 34 Pretreatment filtration device 35 Treated water tank 36 Supply pump 37 High pressure pump 38 Seawater reverse osmosis membrane device (first reverse osmosis membrane device)
39 Pressure Exchanger 40 Back Pressure Valve 41 Booster Pump 45 Ozone Generator 46 Ozone Injection Pump 47 Reaction Tank (First Raw Water Tank)
47a, 47b Partition plate 81 Intake pipe 56 Pipe (first pipe, fine bubble generating means)
57 Piping (first piping, fine bubble generating means)
58 Piping (second piping, fine bubble generating means)
60 control unit 61 control unit (control means)
63 Control unit 100,100A, 100B, 100C, 100D Combined desalination system 105 Fine bubbles A Drainage (second raw water)
D Seawater (first raw water)
P5 Branch point P11 Ozone injection part S7 Flow rate sensor (flow rate detection means)
S9 Pressure sensor (micro bubble generation pressure detection means)

Claims (6)

A first water treatment system that filters the first raw water having a high salinity concentration using the first reverse osmosis membrane device, and a second raw water having a lower salinity than the first raw water, A second desalination system that performs filtration using a reverse osmosis membrane device, and a composite desalination system comprising:
In the first water treatment system, fine bubbles are reduced by reducing the pressure of non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system into the first raw water taken. A composite desalination system comprising fine bubble generating means for generating and discharging. The fine bubble generating means includes
A first pipe connecting an outlet of non-permeated water of the second reverse osmosis membrane device and a first raw water tank for storing the taken first raw water;
A first valve provided on the first raw water tank side of the first pipe;
It is provided downstream of the first valve of the first pipe, and is dissolved in the first raw water tank by rapidly depressurizing the non-permeated water of the second reverse osmosis membrane device in the first raw water tank. A fine bubble generating section for generating and releasing gas as the fine bubbles;
The combined desalination system according to claim 1, comprising: The fine bubble generating means further includes:
A second pipe branched from the first pipe at a position upstream of the first valve and connected to the first raw water tank;
A second valve provided in the second pipe for adjusting the flow rate of the non-permeate water of the second reverse osmosis membrane device;
The combined desalination system according to claim 2, comprising: A flow rate detecting means provided upstream of a branch point of the first piping to the second piping, and detecting a flow rate of non-permeated water of the second reverse osmosis membrane device;
A pressure of non-permeated water of the second reverse osmosis membrane device, which is provided in the first pipe between the first valve and the fine bubble generation unit and is decompressed by the first valve, is detected. Fine bubble generation pressure detection means;
The second reverse osmosis membrane is adjusted to a predetermined flow rate based on the flow rate signal from the flow rate detection unit, while adjusting the degree of pressure reduction of the first valve based on the pressure signal from the fine bubble generation pressure detection unit. Control means for adjusting the opening of the second valve so as to adjust the flow rate of non-permeate water of the apparatus;
The composite desalination system according to claim 3, comprising:   The first raw water tank is divided into a plurality of compartments by a plurality of partition plates, and the water to be treated from which the fine bubbles are discharged is alternately changed in the flow direction up and down to promote mixing with the fine bubbles. The composite desalination system according to any one of claims 2 to 4, which is a reaction tank that promotes decomposition and sterilization of organic substances by crushing the fine bubbles. Furthermore, an ozone generator that generates ozone gas is provided,
3. An ozone injection part for injecting the ozone gas generated by the ozone generator is provided in the first pipe between the first valve and the fine bubble generating part. Item 6. The combined desalination system according to any one of items 5 to 6.

Images