WO2017168721A1 - Filtration layer cleaning method, biological membrane filtration apparatus, and desalination plant - Google Patents

Filtration layer cleaning method, biological membrane filtration apparatus, and desalination plant Download PDF

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Publication number
WO2017168721A1
WO2017168721A1 PCT/JP2016/060810 JP2016060810W WO2017168721A1 WO 2017168721 A1 WO2017168721 A1 WO 2017168721A1 JP 2016060810 W JP2016060810 W JP 2016060810W WO 2017168721 A1 WO2017168721 A1 WO 2017168721A1
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Prior art keywords
water
backwash
reverse osmosis
osmosis membrane
filtration
Prior art date
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PCT/JP2016/060810
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French (fr)
Japanese (ja)
Inventor
慎太郎 田浦
嘉晃 伊藤
英夫 鈴木
英夫 岩橋
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三菱重工業株式会社
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Priority to PCT/JP2016/060810 priority Critical patent/WO2017168721A1/en
Publication of WO2017168721A1 publication Critical patent/WO2017168721A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/46—Regenerating the filtering material in the filter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/04—Aerobic processes using trickle filters
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/06—Aerobic processes using submerged filters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

  • the present disclosure relates to a filtration layer cleaning method, a biological membrane filtration device, and a desalination plant for a biological membrane filtration device that filters raw water through a filtration layer on which a biological membrane is supported.
  • a biofilm filtration apparatus that simultaneously performs physical treatment for filtering turbid components (floating particulates) in raw water and biological treatment with microorganisms by flowing raw water through a filtration layer on which a biofilm is supported.
  • a biofilm filtration apparatus includes a filtration layer in which a filter medium such as sand or anthracite is packed in a tower, and generates a biofilm on the filter medium surface using organic nutrients in water.
  • This biological film removes dissolved organic substances in water and removes turbid components by a filtration layer to purify raw water.
  • Biofilm filtration devices are often used as pretreatment for reverse osmosis membrane devices, for example, in seawater desalination plants.
  • An object of at least some embodiments of the present invention is to provide a filtration layer cleaning method, a biofilm filtration apparatus, and a desalination plant that can perform backwashing appropriately without causing a reduction in production efficiency. is there.
  • a filtration layer cleaning method includes: A method for cleaning a filtration layer of a biofilm filtration device for filtering raw water through a filtration layer carrying a biofilm, Using concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and using backwash water having a salt concentration ratio of 0.6 or more and 1.5 or less with respect to the raw water The filter layer is back-washed.
  • the concentrated water separated by the reverse osmosis membrane has a salt concentration different from that of the raw water.
  • the concentrated water separated by the reverse osmosis membrane has a higher salt concentration than the raw water.
  • the concentrated water separated by the downstream reverse osmosis membrane device is obtained by separating the permeated water obtained by the upstream reverse osmosis membrane device. Therefore, the salt concentration is lower than the raw water.
  • the salt concentration environment around the microorganisms supported on the filtration layer changes, and the movement of the liquid inside and outside the cells due to the osmotic pressure difference is caused. It can happen that the activity of microorganisms is greatly reduced.
  • the present inventors have found a correlation between the activity of microorganisms in the raw water and the salt concentration. That is, it was found that the activity of microorganisms can be properly maintained in an environment where the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less.
  • the filtration layer is backwashed with backwashing water having a salt concentration ratio of 0.6 or more and 1.5 or less with respect to the raw water, thereby being carried on the filtration layer.
  • the activity of the microorganism can be maintained to such an extent that the function of biological treatment by the microorganism can be sufficiently exhibited. For this reason, as described above, it is possible to effectively use the concentrated water, which is advantageous in terms of production efficiency and cost, as the backwash water.
  • the backwash water has a salt concentration ratio of 0.8 to 1.25 with respect to the raw water.
  • the backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
  • the filtered water before being supplied to the reverse osmosis membrane contains fine turbid components, but the salt concentration is almost the same as the raw water. Therefore, like the method of (3) above, the filtered water is mixed with the backwash water, so that the salt concentration of the concentrated water can be made close to that of the raw water. It can be easily adjusted to the range of the salt concentration ratio shown.
  • concentrated water containing almost no turbid components is used by mixing with filtered water, so that the filtration layer by turbid components is used. Contamination can be suppressed.
  • the backwash water further includes the raw water.
  • the salt concentration of the concentrated water can be brought close to that of the raw water by mixing the raw water with the backwash water, and the backwash water is converted into the salt shown in the above (1) or (2). It can be easily adjusted to the concentration ratio range. Compared with the case where only raw water is used as backwash water, in the method (4) above, concentrated water containing almost no turbid components is mixed with raw water and used. Can be suppressed.
  • the reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series
  • the backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane or second concentrated water separated by the second reverse osmosis membrane.
  • the use of the first concentrated water or the second concentrated water having a salt concentration different from that of the raw water as the backwash water can prevent a reduction in production efficiency due to the backwash, and the processing cost. Can be reduced.
  • the second concentrated water separated by the second reverse osmosis membrane is a concentrated water obtained by separating the permeated water having a low salt concentration obtained by the first reverse osmosis membrane by the reverse osmosis membrane, the salt concentration relative to the raw water is usually used. The ratio is less than 1. Therefore, when the first concentrated water having a high salt concentration and the second concentrated water having a low salt concentration are mixed, the concentrated water advantageous from the viewpoint of production efficiency and cost is used, and the above (1) or (2) is shown. Backwash water with a salt concentration ratio can be produced.
  • the backwash time of the filtration layer is 5 minutes or more and 30 minutes or less.
  • the backwash time of the filtration layer is 10 minutes or more and 20 minutes or less.
  • the turbid matter adhering to the filtration layer is removed while maintaining the activity of microorganisms more appropriately. It can be removed sufficiently.
  • the biofilm filtration device includes: A filtration layer supported by a biofilm and configured to filter raw water; Containing concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and filtering backwash water having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water A backwash line to supply the bed, Is provided.
  • a backwash line for supplying backwash water containing concentrated water to the filtration layer is provided, and the salt for the raw water of the backwash water supplied from this backwash line
  • the concentration ratio is 0.6 or more and 1.5 or less.
  • the backwash water has a salt concentration ratio of 0.8 to 1.25 with respect to the raw water.
  • the backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
  • the salt concentration of concentrated water can be approximated to raw
  • concentrated water containing almost no turbid components is used by mixing with filtered water. Contamination can be suppressed.
  • the backwash water further includes the raw water.
  • the salt concentration of the concentrated water can be made close to that of the raw water, and the backwash water is the salt shown in (7) or (8) above. It can be easily adjusted to the concentration ratio range.
  • concentrated water containing almost no turbid components is used by mixing with raw water. Can be suppressed.
  • the reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series,
  • the backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane or second concentrated water separated by the second reverse osmosis membrane.
  • the second concentrated water separated by the second reverse osmosis membrane is a concentrated water obtained by separating the permeated water having a low salt concentration obtained by the first reverse osmosis membrane by the reverse osmosis membrane, the salt concentration relative to the raw water is usually used. The ratio is less than 1. Therefore, if the first concentrated water having a high salt concentration and the second concentrated water having a low salt concentration are mixed, the concentrated water advantageous in terms of production efficiency and cost is used, and the above (7) or (8) is shown. Backwash water with a salt concentration ratio can be produced.
  • the biofilm filtration device is configured to filter the raw water to which the chemical is not added to generate the filtrate water during operation of the biofilm filtration device.
  • a desalination plant according to at least some embodiments of the present invention,
  • the biofilm filtration device according to any one of (7) to (112) above;
  • At least one reverse osmosis membrane device located downstream of the biofilm filtration device and configured to separate filtered water from the filtration layer into the concentrated water and permeated water by a reverse osmosis membrane; Is provided.
  • the raw water is desalinated with high efficiency and low cost. can do.
  • the backwashing of the filtration layer is performed using backwashing water containing concentrated water and having a salt concentration ratio of 0.6 or more and 1.5 with respect to the raw water. Therefore, even if concentrated water having a salt concentration different from that of the raw water is used as backwash water, the activity of the microorganisms can be maintained to such an extent that the function of biological treatment by the microorganisms supported on the filtration layer can be fully exerted. Can do. Therefore, it is possible to use concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
  • FIGS. 1 to 4 are block diagrams showing the desalination plant 1 according to the first to fourth embodiments.
  • a desalination plant 1 includes a biofilm filtration device 10 that filters raw water (seawater) by a filtration layer on which a biofilm is supported, and biofilm filtration. And at least one reverse osmosis membrane device 12A, 12B located on the downstream side of the device 10.
  • a configuration in which two reverse osmosis membrane devices (first reverse osmosis membrane device, second reverse osmosis membrane device) 12A and 12B are connected in series is shown.
  • the configuration of 12A and 12B is not limited to this. For example, a configuration in which only one reverse osmosis membrane device is provided may be used, or a configuration in which three or more reverse osmosis membrane devices are connected in series or in parallel may be used.
  • the biological filtration apparatus 10 has one or more filtration layers (10b, 10c) provided in the filter medium container 10a.
  • the number of layers of the filtration layers (10b, 10c) is not particularly limited, and the biological filtration device 10 may include any number of filtration layers (10b, 10c).
  • the biofilm filtration device 10 has a configuration in which a plurality of filtration layers 10b and 10c are stacked in the vertical direction in a filter medium container 10a.
  • a carbon-based material such as anthracite is used as the filter medium of the upper filter layer 10b
  • a granular filter medium such as silica sand is used as the lower filter layer 10c.
  • a biofilm is supported on the filtration layers 10b and 10c.
  • the biofilm filtration device 10 is supplied with raw water (seawater) by a pump 14.
  • the raw water introduced from the top of the biofilm filtration device 10 passes through the filtration layers 10b and 10c and is discharged from the lower part.
  • turbid components (floating fine particles) in the raw water are removed by the filtration layers 10b and 10c, and dissolved organic substances and the like in the raw water are decomposed and removed by the biofilm.
  • the filtrate discharged from the biological membrane filtration device 10 is stored in the filtrate water tank 16 and then supplied to the reverse osmosis membrane devices 12A and 12B by the pump 18.
  • another filtration device such as an ultrafiltration membrane or a microfiltration membrane may be provided between the biofilm filtration device 10 and the reverse osmosis membrane devices 12A and 12B.
  • the first reverse osmosis membrane device 12A and the second reverse osmosis membrane device 12B are configured to separate filtered water from the filtration layers 10b and 10c into concentrated water and permeated water using a reverse osmosis membrane.
  • filtered water is first supplied to the first reverse osmosis membrane device 12A, and is separated into first concentrated water and first permeated water by the reverse osmosis membrane. For this reason, the salt concentration ratio with respect to the raw water of the 1st concentrated water becomes larger than 1, and the salt concentration ratio with respect to the raw water of the 1st permeated water becomes smaller than 1.
  • the first concentrated water separated by the first reverse osmosis membrane device 12A is stored in the first concentrated water tank 20A, and the first permeated water separated by the first reverse osmosis membrane device 12A is sent to the second reverse osmosis membrane device 12B. Supplied.
  • the first permeated water supplied to the second reverse osmosis membrane device 12B is separated into the second concentrated water and the second permeated water by the reverse osmosis membrane.
  • the first permeated water having a relatively small salt concentration ratio is separated by the reverse osmosis membrane, so that the salt concentration ratio with respect to the raw water is also smaller than 1.
  • the salt concentration ratio of the second permeated water to the raw water is smaller than 1, which is a very low salt concentration.
  • the second concentrated water is stored in the second concentrated water tank 20B.
  • generated in this way is supplied to a user as production water after performing a post-process.
  • the application destination of the biofilm filtration apparatus 10 which concerns on this embodiment is desalination plant 1
  • the biofilm filtration device 10 according to the present embodiment is provided on the upstream side of at least one reverse osmosis membrane device, and the application destination thereof is particularly a configuration where raw water is filtered by a filtration layer carrying a biofilm.
  • the raw water is water containing salt (for example, salinity), and may be, for example, seawater, groundwater, rivers, lake water, treated wastewater, or factory wastewater.
  • salt for example, salinity
  • seawater can be desalinated
  • wastewater treated water, factory wastewater, etc. can be purified to obtain reused water, or clean water can be generated from rivers and lakes.
  • the biofilm filtration device 10 includes concentrated water obtained by separating filtered water from the filtration layers 10b and 10c with a reverse osmosis membrane, and is 0.6 or more and 1 with respect to raw water.
  • a backwash line 30 is further provided for supplying backwash water having a salt concentration ratio of .5 or less to the filtration layers 10b and 10c.
  • the backwash line 30 is configured to supply backwash water from the bottom of the biofilm filtration device 10.
  • the concentrated water used as the backwash water includes at least one of the first concentrated water and the second concentrated water.
  • the filtration layers 10b and 10c are backwashed using this backwash water, and the turbid matter adhering to the filtration layers 10b and 10c (especially the upper filtration layer 10b) is removed.
  • the concentrated water obtained by separation with the reverse osmosis membrane devices 12A and 12B provided at the subsequent stage of the filtration layers 10b and 10c. Including at least one of water).
  • concentrated water is often discarded, so using this concentrated water as backwash water eliminates the need to draw out a large amount of water in the production water production process and avoids a decrease in production efficiency. .
  • the cost reduction effect is great compared to the case where backwash water is procured from the outside.
  • the concentrated water separated by the reverse osmosis membrane has a salt concentration different from that of the raw water.
  • the first concentrated water separated by the reverse osmosis membrane has a higher salt concentration than the raw water.
  • the second concentrated water separated by the second reverse osmosis membrane device 12B is obtained by separating the permeated water obtained by the upstream first reverse osmosis membrane device 12A, and therefore has a lower salt concentration than the raw water.
  • FIG. 5 is a graph showing the correlation between the survival rate (activity) of microorganisms and the salt concentration ratio. As shown in FIG. 5, in an environment where the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less, the survival rate of the microorganisms is maintained at about 50% or more.
  • the survival rate of microorganisms is approximately 50% or more, the survival rate of microorganisms will be sufficiently recovered by the next backwash time, and it will contain concentrated water. It can be avoided that microorganisms continue to decrease by backwashing using backwashing water.
  • FIG. 6 is a graph showing the relationship between culture time and SS concentration (concentration of suspended solids in seawater).
  • ⁇ specific growth rate [h ⁇ 1 ]
  • t time
  • Z cell amount / ml.
  • the filtration layers 10b and 10c are backwashed by using the backwash water having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water.
  • the activity of the microorganisms can be maintained to such an extent that the function of biological treatment by the microorganisms supported by the microorganisms can be sufficiently exerted. For this reason, as described above, it is possible to effectively use the concentrated water, which is advantageous in terms of production efficiency and cost, as the backwash water.
  • the backwash water may have a salt concentration ratio of 0.8 or more and 1.25 or less with respect to the raw water. According to this, the activity reduction of the microorganisms by supply of concentrated water can be suppressed more effectively, and the biological treatment function by the biofilm filtration apparatus 10 can be maintained more appropriately. Moreover, when normal operation is resumed after backwashing, the time until the microorganisms return to normal activity can be shortened.
  • the backwash time of the filtration layers 10b and 10c may be 5 minutes or more and 30 minutes or less. Alternatively, the backwash time of the filtration layers 10b and 10c may be 10 minutes or more and 20 minutes or less. According to this, by making the backwash time of the filtration layer 5 minutes or more and 30 minutes or less, the turbid matter adhering to the filtration layers 10b and 10c is appropriately removed while appropriately maintaining the activity of the microorganisms. Can do.
  • the biofilm filtration device 10 may be configured to filter raw water to which chemicals such as a flocculant are not added during operation to generate filtered water. That is, the biofilm filtration device 10 may be configured to perform a pre-drug pretreatment. According to this, in order to reduce the environmental load caused by adding chemicals such as a flocculant to the raw water, the biofilm filtration apparatus 10 configured to perform the pre-drug pretreatment also has the above-described configuration. This makes it possible to perform appropriate backwashing at low cost.
  • FIG. 1 is a configuration diagram illustrating a biofilm filtration device 10 according to the first embodiment.
  • the biofilm filtration device 10 according to the first embodiment is configured to backwash the filtration layers 10b and 10c with backwash water containing the first concentrated water separated by the first reverse osmosis membrane device 12A. Configured to do.
  • the first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water containing the first concentrated water to the filtration layers 10 b and 10 c, and backwash water supplied from the backwash line 30.
  • the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
  • the first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored.
  • the supply amount of the first concentrated water from the first concentrated water tank 20 ⁇ / b> A to the backwash water tank 32 is adjusted by a valve 34.
  • the backwash water (1st concentrated water) stored in the backwash water tank 32 is supplied to the filtration layers 10b and 10c via the backwash water line 30 at the time of the backwashing of the biofilm filtration apparatus 10.
  • natural water is used as backwash water, the activity of microorganisms is maintained to such an extent that the function of the biological treatment by the microorganisms supported by the filtration layer can be sufficiently exhibited. be able to. Therefore, it is possible to use the first concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
  • the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
  • FIG. 2 is a configuration diagram showing the biofilm filtration device 10 according to the second embodiment.
  • the biofilm filtration device 10 according to the second embodiment includes the first concentrated water separated by the first reverse osmosis membrane device 12A and the filtered water filtered by the biofilm filtration device 10. It comprises so that the backwashing of the filtration layers 10b and 10c may be performed by the backwash water contained.
  • the first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water including the first concentrated water and filtered water to the filtration layers 10b and 10c.
  • the salt concentration ratio of the washing water to the raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
  • the first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored.
  • the supply amount of the first concentrated water from the first concentrated water tank 20 ⁇ / b> A to the backwash water tank 32 is adjusted by a valve 34.
  • the backwash water tank 32 is also supplied with filtered water from the filtered water tank 16.
  • the supply amount of filtrate water from the filtrate water tank 16 to the backwash water tank 32 is adjusted by a valve 36.
  • the salt concentration ratio of the backwash water may be adjusted to the above range.
  • the backwash water (mixed water of the first concentrated water and the filtered water) stored in the backwash water tank 32 is filtered through the backwash water line when the biofilm filtration device 10 is backwashed. To be supplied.
  • the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
  • the 1st concentrated water for backwashing, the fall of production efficiency by backwashing can be prevented, and reduction of processing cost can be aimed at. Furthermore, by mixing the filtered water with the backwash water, the salt concentration of the concentrated water can be brought close to the raw water, and the backwash water can be easily adjusted to the above-described salt concentration ratio range. In addition, compared with the case where only filtered water is used as backwash water, contamination of the filtration layer due to turbid components can be suppressed by using concentrated water containing almost no turbid components mixed with filtered water.
  • FIG. 3 is a configuration diagram showing the biofilm filtration device 10 according to the third embodiment.
  • the biofilm filtration device 10 according to the second embodiment includes a filtration layer 10b, by backwash water containing the first concentrated water separated by the first reverse osmosis membrane device 12A and raw water. 10c is configured to perform backwashing.
  • the first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water including the first concentrated water and raw water to the filtration layers 10 b and 10 c, and the backwash supplied from the backwash line 30.
  • the salt concentration ratio of water to raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
  • the first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored.
  • the supply amount of the first concentrated water from the first concentrated water tank 20 ⁇ / b> A to the backwash water tank 32 is adjusted by a valve 34.
  • the backwash water tank 32 is also supplied with raw water from a raw water tank (not shown).
  • the amount of raw water supplied to the backwash water tank 32 is adjusted by a valve 38. By controlling these valves 34 and 38, the salt concentration ratio of the backwash water may be adjusted to the above range. Then, the backwash water (mixed water of the first concentrated water and the raw water) stored in the backwash water tank 32 is supplied to the filtration layers 10b and 10c via the backwash water line when the biofilm filtration device 10 is backwashed. Supplied. In the illustrated example, the case where the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
  • the 1st concentrated water for backwashing, the fall of production efficiency by backwashing can be prevented, and reduction of processing cost can be aimed at. Furthermore, by mixing the raw water with the backwash water, the salt concentration of the concentrated water can be brought close to the raw water, and the backwash water can be easily adjusted to the above-described salt concentration ratio range. In addition, compared with the case where only filtered water is used as backwash water, contamination of the filtration layer due to turbid components can be suppressed by using concentrated water containing almost no turbid components mixed with filtered water.
  • FIG. 4 is a configuration diagram showing the biofilm filtration device 10 according to the fourth embodiment.
  • the biofilm filtration device 10 according to the fourth embodiment includes a first concentrated water separated by the first reverse osmosis membrane device 12A and a second separated by the second reverse osmosis membrane device 12B.
  • the backwashing water containing concentrated water is configured to backwash the filtration layers 10b and 10c.
  • the first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water containing the first concentrated water and the second concentrated water to the filtration layers 10 b and 10 c, and is supplied from the backwash line 30.
  • the salt concentration ratio of the backwash water to the raw water is 0.6 to 1.5, or 0.8 to 1.25.
  • the first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored.
  • the supply amount of the first concentrated water from the first concentrated water tank 20 ⁇ / b> A to the backwash water tank 32 is adjusted by a valve 34.
  • the backwash water tank 32 is also supplied with the second concentrated water from the second concentrated water tank 20B.
  • the supply amount of the second concentrated water from the second concentrated water tank 20 ⁇ / b> B to the backwash water tank 32 is adjusted by the valve 40.
  • the salt concentration ratio of the backwash water may be adjusted to the above range.
  • the backwash water (mixed water of the first concentrated water and the second concentrated water) stored in the backwash water tank 32 is filtered through the backwash water line when the biofilm filtration device 10 is backwashed. , 10c.
  • the backwash water having the above-mentioned salt concentration ratio is generated using concentrated water advantageous in terms of production efficiency and cost. can do.
  • the salt concentration ratio with respect to the raw water of the backwash water may be adjusted to the above-described range by mixing water supplied from outside the system with the concentrated water. .
  • the filtration layer 10b is formed using backwash water containing concentrated water and having a salt concentration ratio of 0.6 or more and 1.5 with respect to raw water.
  • 10c is backwashed, so that even when concentrated water having a salt concentration different from that of the raw water is used as backwash water, the biological treatment function by the microorganisms supported by the filtration layers 10b, 10c is fully exhibited.
  • the activity of the microorganism can be maintained to the extent possible. Therefore, it is possible to use concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
  • the present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
  • an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
  • the expression “comprising”, “including”, or “having” one constituent element is not an exclusive expression for excluding the existence of another constituent element.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Biodiversity & Conservation Biology (AREA)
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  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

A filtration layer cleaning method for a biological membrane filtration apparatus, which filters raw water using a filtration layer on which a biological membrane has been loaded, backwashes the filtration layer using backwash water comprising a concentrate obtained by separation of filtration layer-filtered water using a reverse osmosis membrane and having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water.

Description

ろ過層洗浄方法及び生物膜ろ過装置、並びに淡水化プラントFiltration layer cleaning method, biofilm filtration device, and desalination plant
　本開示は、生物膜が担持されたろ過層により原水をろ過する生物膜ろ過装置のろ過層洗浄方法及び生物膜ろ過装置、並びに淡水化プラントに関する。 The present disclosure relates to a filtration layer cleaning method, a biological membrane filtration device, and a desalination plant for a biological membrane filtration device that filters raw water through a filtration layer on which a biological membrane is supported.
　従来、生物膜が担持されたろ過層に原水を流すことによって、原水中の濁質分（浮遊微粒子）をろ過する物理的処理と、微生物による生物処理とを同時に行う生物膜ろ過装置が知られている。例えば、生物膜ろ過装置は、砂やアンスラサイト等のろ材が塔内に充填されたろ過層を備え、水中の有機栄養物を利用してろ材表面に生物膜を生成させる。この生物膜により水中の溶存有機物を除去するとともにろ過層により濁質分を除去し、原水を浄化するようになっている。
　生物膜ろ過装置は、例えば海水の淡水化プラントなどにおいて、逆浸透膜装置の前処理としても多く用いられている。 Conventionally, there has been known a biofilm filtration apparatus that simultaneously performs physical treatment for filtering turbid components (floating particulates) in raw water and biological treatment with microorganisms by flowing raw water through a filtration layer on which a biofilm is supported. ing. For example, a biofilm filtration apparatus includes a filtration layer in which a filter medium such as sand or anthracite is packed in a tower, and generates a biofilm on the filter medium surface using organic nutrients in water. This biological film removes dissolved organic substances in water and removes turbid components by a filtration layer to purify raw water.
Biofilm filtration devices are often used as pretreatment for reverse osmosis membrane devices, for example, in seawater desalination plants.
　このような生物膜ろ過装置においても、他のろ過装置と同様に、ろ過層に付着した濁質分が蓄積すると目詰まりによって圧損が上昇してしまうため、ろ過層に付着した濁質分を除去する必要がある。
　典型的なろ過装置においては、通常、ろ過層に逆洗水を流入させて、濁質分等をろ過装置から排出させる逆洗が行われる。例えば、特許文献１には、逆洗水として、ろ過工程でろ過処理されたろ過水を使用することが記載されている。また、この文献には、逆洗水として原水を使用することも記載されている。 In such a biofilm filtration device, as with other filtration devices, the accumulation of turbid components adhering to the filtration layer increases the pressure loss due to clogging, so the turbid component adhering to the filtration layer is removed. There is a need to.
In a typical filtration device, backwashing is usually performed in which backwash water is allowed to flow into the filtration layer and turbid components and the like are discharged from the filtration device. For example, Patent Document 1 describes the use of filtered water that has been filtered in the filtration step as backwash water. This document also describes the use of raw water as backwash water.
特公昭５４－１８７８０号公報Japanese Patent Publication No.54-18780
　しかしながら、特許文献１に記載されるように、ろ過層を逆洗する際の逆洗水として原水を用いる場合、原水中には濁質分が多く含まれるため、適切な洗浄を行えないばかりか、ろ過層のうち逆洗水を導入する面まで濁質分が付着してしまう可能性がある。
　一方、ろ過工程でろ過処理されたろ過水を逆洗水として用いる場合、原水より濁質分は低減しているものの、通常であれば後段の逆浸透膜装置等で除去される微粒径の濁質分は残存しているため、やはり適切な洗浄を行うことは難しい。またこの場合、利用価値のある生産水の生成プロセス中の水を引き抜いて利用することになるため、生産効率が低下してしまうという問題もあった。同様に、例えば逆浸透膜装置で得られる透過水を逆洗水として用いる場合にも、生産効率の低下を引き起こすことになる。 However, as described in Patent Document 1, when raw water is used as backwash water when backwashing the filtration layer, since the raw water contains a large amount of turbidity, it cannot be properly washed. In the filtration layer, turbid components may adhere to the surface where backwash water is introduced.
On the other hand, when the filtered water filtered in the filtration step is used as backwash water, the turbidity content is reduced from the raw water, but usually the fine particle size removed by the reverse osmosis membrane device etc. in the latter stage Since turbidity remains, it is still difficult to perform proper cleaning. Further, in this case, there is a problem in that the production efficiency is lowered because water in the production process of production water having utility value is drawn out and used. Similarly, for example, when permeate obtained by a reverse osmosis membrane device is used as backwash water, production efficiency is lowered.
　本発明の少なくとも幾つかの実施形態の目的は、生産効率の低下を引き起こすことなく、適切に逆洗を行うことができるろ過層洗浄方法及び生物膜ろ過装置、並びに淡水化プラントを提供することである。 An object of at least some embodiments of the present invention is to provide a filtration layer cleaning method, a biofilm filtration apparatus, and a desalination plant that can perform backwashing appropriately without causing a reduction in production efficiency. is there.
（１）本発明の少なくとも幾つかの実施形態に係るろ過層洗浄方法は、
　生物膜が担持されたろ過層により原水をろ過する生物膜ろ過装置のろ過層洗浄方法であって、
　前記ろ過層からのろ過水を逆浸透膜で分離して得られる濃縮水を含み、且つ、前記原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を用いて、前記ろ過層を逆洗する。 (1) A filtration layer cleaning method according to at least some embodiments of the present invention includes:
A method for cleaning a filtration layer of a biofilm filtration device for filtering raw water through a filtration layer carrying a biofilm,
Using concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and using backwash water having a salt concentration ratio of 0.6 or more and 1.5 or less with respect to the raw water The filter layer is back-washed.
　上記（１）の方法によれば、ろ過層の洗浄に際して、ろ過層の後段に設けられた逆浸透膜で分離して得られる濃縮水を用いるようにしている。通常、濃縮水は廃棄されることが多いため、この濃縮水を逆洗水として用いることで生産水の生成プロセス中の水を多量に引き抜いて利用する必要がなくなり、生産効率の低下を回避できる。また、系内の水を有効利用することができるため、外部から逆洗水を調達する場合に比べてコストの削減効果も大きい。 According to the above method (1), when the filtration layer is washed, concentrated water obtained by separation with a reverse osmosis membrane provided downstream of the filtration layer is used. Normally, concentrated water is often discarded, so using this concentrated water as backwash water eliminates the need to draw out a large amount of water in the production water production process and avoids a decrease in production efficiency. . In addition, since the water in the system can be used effectively, the cost reduction effect is great compared to the case where backwash water is procured from the outside.
　ところで、逆浸透膜で分離された濃縮水は、原水とは塩濃度が相違する。例えば、生物膜ろ過装置のろ過水が供給される逆浸透膜装置の場合、逆浸透膜で分離された濃縮水は原水よりも塩濃度が高くなる。一方、複数の逆浸透膜装置が直列に設けられている場合、下流側の逆浸透膜装置で分離された濃縮水は、上流側の逆浸透膜装置で得られる透過水を分離したものであるため原水よりも塩濃度が低くなる。このように、原水とは塩濃度が異なる濃縮水を逆洗水として利用すると、ろ過層に担持された微生物周囲の塩濃度環境が変化し、浸透圧差によって微生物の細胞内外での液の移動が起こって微生物の活性が大幅に低下する可能性がある。
　そこで、本発明者らは、鋭意検討の結果、原水中の微生物の活性と塩濃度との間の相関関係を見出した。すなわち、原水に対する塩濃度比が０．６以上且つ１．５以下の環境下において、微生物の活性を適正に維持できることがわかった。
　上記（１）の方法によれば、原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を用いてろ過層を逆洗することで、ろ過層に担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。このため、上述したように生産効率およびコスト面から有利な濃縮水を逆洗水として有効利用することが可能となる。 By the way, the concentrated water separated by the reverse osmosis membrane has a salt concentration different from that of the raw water. For example, in the case of a reverse osmosis membrane device to which filtered water from a biofilm filtration device is supplied, the concentrated water separated by the reverse osmosis membrane has a higher salt concentration than the raw water. On the other hand, when a plurality of reverse osmosis membrane devices are provided in series, the concentrated water separated by the downstream reverse osmosis membrane device is obtained by separating the permeated water obtained by the upstream reverse osmosis membrane device. Therefore, the salt concentration is lower than the raw water. As described above, when concentrated water having a salt concentration different from that of the raw water is used as backwash water, the salt concentration environment around the microorganisms supported on the filtration layer changes, and the movement of the liquid inside and outside the cells due to the osmotic pressure difference is caused. It can happen that the activity of microorganisms is greatly reduced.
As a result of intensive studies, the present inventors have found a correlation between the activity of microorganisms in the raw water and the salt concentration. That is, it was found that the activity of microorganisms can be properly maintained in an environment where the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less.
According to the method of (1) above, the filtration layer is backwashed with backwashing water having a salt concentration ratio of 0.6 or more and 1.5 or less with respect to the raw water, thereby being carried on the filtration layer. The activity of the microorganism can be maintained to such an extent that the function of biological treatment by the microorganism can be sufficiently exhibited. For this reason, as described above, it is possible to effectively use the concentrated water, which is advantageous in terms of production efficiency and cost, as the backwash water.
（２）幾つかの実施形態では、上記（１）の方法において、
　前記逆洗水は、前記原水に対して０．８以上且つ１．２５以下の塩濃度比を有する。 (2) In some embodiments, in the method of (1) above,
The backwash water has a salt concentration ratio of 0.8 to 1.25 with respect to the raw water.
　上記（２）の方法によれば、０．８以上且つ１．２５以下の塩濃度比を有する逆洗水を用いることによって、濃縮水の供給による微生物の活性低下をより効果的に抑制でき、生物膜ろ過装置による生物処理機能をより適正に維持できる。また、逆洗後に通常運転を再開した際、微生物が通常の活性に戻るまでの時間を短くすることができる。 According to the method of (2) above, by using backwash water having a salt concentration ratio of 0.8 or more and 1.25 or less, it is possible to more effectively suppress microbial activity reduction due to the supply of concentrated water, The biological treatment function by the biofilm filtration device can be maintained more appropriately. Moreover, when normal operation is resumed after backwashing, the time until the microorganisms return to normal activity can be shortened.
（３）幾つかの実施形態では、上記（１）又は（２）の方法において、
　前記逆洗水は、前記逆浸透膜に供給される前の前記ろ過水をさらに含む。 (3) In some embodiments, in the method of (1) or (2) above,
The backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
　逆浸透膜に供給される前のろ過水は、微粒径の濁質分を含んでいるが塩濃度は原水と概ね同じである。そのため、上記（３）の方法のように、逆洗水にろ過水を混合させることで、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上記（１）又は（２）で示した塩濃度比の範囲に容易に調整することができる。なお、逆洗水としてろ過水のみを用いる場合に比べて、上記（３）の方法では、濁質分を殆ど含まない濃縮水をろ過水と混合して利用するため、濁質分によるろ過層の汚染を抑制できる。 The filtered water before being supplied to the reverse osmosis membrane contains fine turbid components, but the salt concentration is almost the same as the raw water. Therefore, like the method of (3) above, the filtered water is mixed with the backwash water, so that the salt concentration of the concentrated water can be made close to that of the raw water. It can be easily adjusted to the range of the salt concentration ratio shown. In addition, compared with the case where only filtered water is used as the backwash water, in the method of (3) above, concentrated water containing almost no turbid components is used by mixing with filtered water, so that the filtration layer by turbid components is used. Contamination can be suppressed.
（４）幾つかの実施形態では、上記（１）乃至（３）の何れかの方法において、
　前記逆洗水は、前記原水をさらに含む。 (4) In some embodiments, in any of the above methods (1) to (3),
The backwash water further includes the raw water.
　上記（４）の方法によれば、逆洗水に原水を混合させることによって、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上記（１）又は（２）で示した塩濃度比の範囲に容易に調整することができる。なお、逆洗水として原水のみを用いる場合に比べて、上記（４）の方法では、濁質分を殆ど含まない濃縮水を原水と混合して利用するため、濁質分によるろ過層の汚染を抑制できる。 According to the method of (4) above, the salt concentration of the concentrated water can be brought close to that of the raw water by mixing the raw water with the backwash water, and the backwash water is converted into the salt shown in the above (1) or (2). It can be easily adjusted to the concentration ratio range. Compared with the case where only raw water is used as backwash water, in the method (4) above, concentrated water containing almost no turbid components is mixed with raw water and used. Can be suppressed.
（５）幾つかの実施形態では、上記（１）乃至（４）の何れかの方法において、
　前記逆浸透膜が、直列に接続された第１逆浸透膜および第２逆浸透膜を含み、
　前記逆洗水は、前記第１逆浸透膜で分離された第１濃縮水、または、前記第２逆浸透膜で分離された第２濃縮水の少なくとも一方を含む。 (5) In some embodiments, in any of the above methods (1) to (4),
The reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series,
The backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane or second concentrated water separated by the second reverse osmosis membrane.
　上記（５）の方法によれば、原水とは異なる塩濃度を有する第１濃縮水又は第２濃縮水を逆洗水として用いることで、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　なお、第２逆浸透膜で分離された第２濃縮水は、第１逆浸透膜で得られる低塩濃度の透過水を逆浸透膜で分離した濃縮水であるため、通常、原水に対する塩濃度比は１未満である。そのため、高塩濃度の第１濃縮水と低塩濃度の第２濃縮水を混合させれば、生産効率およびコスト面から有利な濃縮水を用いて、上記（１）又は（２）で示した塩濃度比の逆洗水を生成することができる。 According to the method of (5) above, the use of the first concentrated water or the second concentrated water having a salt concentration different from that of the raw water as the backwash water can prevent a reduction in production efficiency due to the backwash, and the processing cost. Can be reduced.
Since the second concentrated water separated by the second reverse osmosis membrane is a concentrated water obtained by separating the permeated water having a low salt concentration obtained by the first reverse osmosis membrane by the reverse osmosis membrane, the salt concentration relative to the raw water is usually used. The ratio is less than 1. Therefore, when the first concentrated water having a high salt concentration and the second concentrated water having a low salt concentration are mixed, the concentrated water advantageous from the viewpoint of production efficiency and cost is used, and the above (1) or (2) is shown. Backwash water with a salt concentration ratio can be produced.
（６）幾つかの実施形態では、上記（１）乃至（５）の何れかの方法において、
　前記ろ過層の逆洗時間は、５分以上３０分以内である。 (6) In some embodiments, in any of the above methods (1) to (5),
The backwash time of the filtration layer is 5 minutes or more and 30 minutes or less.
　上記（６）の方法によれば、ろ過層の逆洗時間を５分以上３０分以内とすることによって、微生物の活性を適正に維持しながら、ろ過層に付着した濁質分を適切に除去することができる。 According to the method of (6) above, by setting the backwash time of the filtration layer to 5 minutes or more and 30 minutes or less, turbidity adhering to the filtration layer is appropriately removed while maintaining the activity of microorganisms properly. can do.
（６’）幾つかの実施形態では、上記（１）乃至（５）の何れかの方法において、
　前記ろ過層の逆洗時間は、１０分以上２０分以内である。 (6 ′) In some embodiments, in any one of the methods (1) to (5),
The backwash time of the filtration layer is 10 minutes or more and 20 minutes or less.
　上記（６’）の方法によれば、ろ過層の逆洗時間を１０分以上２０分以内とすることによって、微生物の活性をより一層適正に維持しながら、ろ過層に付着した濁質分を十分に除去することができる。 According to the above method (6 ′), by setting the backwash time of the filtration layer to 10 minutes or more and 20 minutes or less, the turbid matter adhering to the filtration layer is removed while maintaining the activity of microorganisms more appropriately. It can be removed sufficiently.
（７）本発明の少なくとも幾つかの実施形態に係る生物膜ろ過装置は、
　生物膜が担持され、原水をろ過するように構成されたろ過層と、
　前記ろ過層からのろ過水を逆浸透膜で分離して得られる濃縮水を含み、且つ、前記原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を前記ろ過層に供給するための逆洗ラインと、
を備える。 (7) The biofilm filtration device according to at least some embodiments of the present invention includes:
A filtration layer supported by a biofilm and configured to filter raw water;
Containing concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and filtering backwash water having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water A backwash line to supply the bed,
Is provided.
　上記（７）の生物膜ろ過装置によれば、濃縮水を含む逆洗水をろ過層に供給するための逆洗ラインを備えており、この逆洗ラインから供給する逆洗水の原水に対する塩濃度比を０．６以上且つ１．５以下としている。これにより、原水とは異なる塩濃度を有する濃縮水を逆洗水として用いても、ろ過層に担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。したがって、濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。 According to the biofilm filtration device of (7) above, a backwash line for supplying backwash water containing concentrated water to the filtration layer is provided, and the salt for the raw water of the backwash water supplied from this backwash line The concentration ratio is 0.6 or more and 1.5 or less. As a result, even if concentrated water having a salt concentration different from that of the raw water is used as the backwash water, the activity of the microorganisms can be maintained to such an extent that the function of biological treatment by the microorganisms supported on the filtration layer can be sufficiently exhibited. it can. Therefore, it is possible to use concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
（８）幾つかの実施形態では、上記（７）の構成において、
　前記逆洗水は、前記原水に対して０．８以上且つ１．２５以下の塩濃度比を有する。 (8) In some embodiments, in the configuration of (7) above,
The backwash water has a salt concentration ratio of 0.8 to 1.25 with respect to the raw water.
　上記（８）の構成によれば、０．８以上且つ１．２５以下の塩濃度比を有する逆洗水を用いることによって、濃縮水の供給による微生物の活性低下をより効果的に抑制でき、生物膜ろ過装置による生物処理機能をより適正に維持できる。また、逆洗後に通常運転を再開した際、微生物が通常の活性に戻るまでの時間を短くすることができる。 According to the configuration of (8) above, by using backwash water having a salt concentration ratio of 0.8 or more and 1.25 or less, it is possible to more effectively suppress microbial activity reduction due to the supply of concentrated water, The biological treatment function by the biofilm filtration device can be maintained more appropriately. Moreover, when normal operation is resumed after backwashing, the time until the microorganisms return to normal activity can be shortened.
（９）幾つかの実施形態では、上記（７）又は（８）の構成において、
　前記逆洗水は、前記逆浸透膜に供給される前の前記ろ過水をさらに含む。 (9) In some embodiments, in the above configuration (7) or (8),
The backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
　上記（９）の構成によれば、逆洗水にろ過水を混合させることで、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上記（８）又は（９）で示した塩濃度比の範囲に容易に調整することができる。なお、逆洗水としてろ過水のみを用いる場合に比べて、上記（９）の構成では、濁質分を殆ど含まない濃縮水をろ過水と混合して利用するため、濁質分によるろ過層の汚染を抑制できる。 According to the structure of said (9), the salt concentration of concentrated water can be approximated to raw | natural water by mixing filtered water with backwash water, and backwash water was shown by said (8) or (9). It can be easily adjusted to the range of the salt concentration ratio. In addition, compared with the case where only filtered water is used as the backwash water, in the configuration of (9), concentrated water containing almost no turbid components is used by mixing with filtered water. Contamination can be suppressed.
（１０）幾つかの実施形態では、上記（７）乃至（９）の何れかの構成において、
　前記逆洗水は、前記原水をさらに含む。 (10) In some embodiments, in any one of the above configurations (7) to (9),
The backwash water further includes the raw water.
　上記（１０）の構成によれば、逆洗水に原水を混合させることで、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上記（７）又は（８）で示した塩濃度比の範囲に容易に調整することができる。なお、逆洗水として原水のみを用いる場合に比べて、上記（１０）の構成では、濁質分を殆ど含まない濃縮水を原水と混合して利用するため、濁質分によるろ過層の汚染を抑制できる。 According to the configuration of (10) above, by mixing the raw water with the backwash water, the salt concentration of the concentrated water can be made close to that of the raw water, and the backwash water is the salt shown in (7) or (8) above. It can be easily adjusted to the concentration ratio range. In addition, compared with the case where only raw water is used as backwash water, in the configuration of (10) above, concentrated water containing almost no turbid components is used by mixing with raw water. Can be suppressed.
（１１）幾つかの実施形態では、上記（７）乃至（１０）の何れかの構成において、
　前記逆浸透膜が、直列に接続された第１逆浸透膜および第２逆浸透膜を含み、
　前記逆洗水は、前記第１逆浸透膜で分離された第１濃縮水、または、前記第２逆浸透膜で分離された第２濃縮水の少なくとも一方を含む。 (11) In some embodiments, in any one of the above configurations (7) to (10),
The reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series,
The backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane or second concentrated water separated by the second reverse osmosis membrane.
　上記（１１）の構成によれば、原水とは異なる塩濃度を有する第１濃縮水又は第２濃縮水を逆洗水として用いることで、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　なお、第２逆浸透膜で分離された第２濃縮水は、第１逆浸透膜で得られる低塩濃度の透過水を逆浸透膜で分離した濃縮水であるため、通常、原水に対する塩濃度比は１未満である。そのため、高塩濃度の第１濃縮水と低塩濃度の第２濃縮水を混合させれば、生産効率およびコスト面から有利な濃縮水を用いて、上記（７）又は（８）で示した塩濃度比の逆洗水を生成することができる。 According to the configuration of (11) above, by using the first concentrated water or the second concentrated water having a salt concentration different from that of the raw water as the backwash water, it is possible to prevent a reduction in production efficiency due to the backwash, and the processing cost. Can be reduced.
Since the second concentrated water separated by the second reverse osmosis membrane is a concentrated water obtained by separating the permeated water having a low salt concentration obtained by the first reverse osmosis membrane by the reverse osmosis membrane, the salt concentration relative to the raw water is usually used. The ratio is less than 1. Therefore, if the first concentrated water having a high salt concentration and the second concentrated water having a low salt concentration are mixed, the concentrated water advantageous in terms of production efficiency and cost is used, and the above (7) or (8) is shown. Backwash water with a salt concentration ratio can be produced.
（１２）幾つかの実施形態では、上記（７）乃至（１１）の何れかの構成において、
　前記生物膜ろ過装置は、前記生物膜ろ過装置の運転中、薬品が添加されていない前記原水をろ過して前記ろ過水を生成するように構成される。 (12) In some embodiments, in any one of the above configurations (7) to (11),
The biofilm filtration device is configured to filter the raw water to which the chemical is not added to generate the filtrate water during operation of the biofilm filtration device.
　上記（１２）の構成によれば、原水に対して凝集剤等の薬品を添加することによる環境負荷を軽減するために、無薬注前処理を行うようにした生物膜ろ過装置においても、上記（７）乃至（１１）の何れかの構成を備えることによって、低コストで且つ適切な逆洗を行うことができる。 According to the configuration of (12) above, even in the biofilm filtration device that performs the pre-treatment without chemical injection in order to reduce the environmental load caused by adding chemicals such as a flocculant to the raw water, By including any one of the constitutions (7) to (11), it is possible to perform appropriate backwashing at low cost.
（１３）本発明の少なくとも幾つかの実施形態に係る淡水化プラントは、
　上記（７）乃至（１１２）の何れかに記載の生物膜ろ過装置と、
　前記生物膜ろ過装置の下流側に位置し、前記ろ過層からのろ過水を逆浸透膜によって前記濃縮水と透過水とに分離するように構成された少なくとも一つの逆浸透膜装置と、
を備える。 (13) A desalination plant according to at least some embodiments of the present invention,
The biofilm filtration device according to any one of (7) to (112) above;
At least one reverse osmosis membrane device located downstream of the biofilm filtration device and configured to separate filtered water from the filtration layer into the concentrated water and permeated water by a reverse osmosis membrane;
Is provided.
　上記（１３）の淡水化プラントによれば、逆洗による生産効率の低下を防止でき、且つコストを削減可能な生物膜ろ過装置を備えているので、高効率且つ低コストで原水を淡水化処理することができる。 According to the desalination plant of (13) above, since it is equipped with a biofilm filtration device that can prevent a reduction in production efficiency due to backwashing and can reduce costs, the raw water is desalinated with high efficiency and low cost. can do.
　本発明の少なくとも幾つかの実施形態によれば、濃縮水を含み、且つ、原水に対する塩濃度比が０．６以上且つ１．５である逆洗水を用いてろ過層の逆洗を行うようにしたので、原水とは異なる塩濃度を有する濃縮水を逆洗水として用いても、ろ過層に担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。したがって、濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。 According to at least some embodiments of the present invention, the backwashing of the filtration layer is performed using backwashing water containing concentrated water and having a salt concentration ratio of 0.6 or more and 1.5 with respect to the raw water. Therefore, even if concentrated water having a salt concentration different from that of the raw water is used as backwash water, the activity of the microorganisms can be maintained to such an extent that the function of biological treatment by the microorganisms supported on the filtration layer can be fully exerted. Can do. Therefore, it is possible to use concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
第１実施形態に係る淡水化プラントの構成図である。It is a block diagram of the desalination plant which concerns on 1st Embodiment. 第２実施形態に係る淡水化プラントの構成図である。It is a block diagram of the desalination plant which concerns on 2nd Embodiment. 第３実施形態に係る淡水化プラントの構成図である。It is a block diagram of the desalination plant which concerns on 3rd Embodiment. 第４実施形態に係る淡水化プラントの構成図である。It is a block diagram of the desalination plant which concerns on 4th Embodiment. 微生物の生存率と塩濃度比との相関関係を示すグラフである。It is a graph which shows correlation with the survival rate of microorganisms, and salt concentration ratio. 微生物の培養試験の結果を示すグラフである。It is a graph which shows the result of the culture | cultivation test of microorganisms.
　以下、添付図面を参照して本発明の幾つかの実施形態について説明する。ただし、実施形態として記載されている又は図面に示されている構成部品の寸法、材質、形状、その相対的配置等は、本発明の範囲をこれに限定する趣旨ではなく、単なる説明例にすぎない。 Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
　最初に、図１～図４を参照して、幾つかの実施形態に係る淡水化プラント１の概略的な構成について説明する。なお、図１～図４は、第１実施形態～第４実施形態に係る淡水化プラント１を示すブロック図である。 First, a schematic configuration of a desalination plant 1 according to some embodiments will be described with reference to FIGS. 1 to 4 are block diagrams showing the desalination plant 1 according to the first to fourth embodiments.
　図１～図４に例示するように、幾つかの実施形態に係る淡水化プラント１は、生物膜が担持されたろ過層により原水（海水）をろ過する生物膜ろ過装置１０と、生物膜ろ過装置１０の下流側に位置する少なくとも一つの逆浸透膜装置１２Ａ，１２Ｂと、を備える。
　なお、図示される例では、２基の逆浸透膜装置（第１逆浸透膜装置、第２逆浸透膜装置）１２Ａ，１２Ｂが直列に接続された構成を示しているが、逆浸透膜装置１２Ａ，１２Ｂの構成はこれに限定されるものではない。例えば、１基の逆浸透膜装置のみが設けられた構成であってもよいし、３基以上の逆浸透膜装置が直列又は並列に接続された構成であってもよい。 As illustrated in FIGS. 1 to 4, a desalination plant 1 according to some embodiments includes a biofilm filtration device 10 that filters raw water (seawater) by a filtration layer on which a biofilm is supported, and biofilm filtration. And at least one reverse osmosis membrane device 12A, 12B located on the downstream side of the device 10.
In the illustrated example, a configuration in which two reverse osmosis membrane devices (first reverse osmosis membrane device, second reverse osmosis membrane device) 12A and 12B are connected in series is shown. The configuration of 12A and 12B is not limited to this. For example, a configuration in which only one reverse osmosis membrane device is provided may be used, or a configuration in which three or more reverse osmosis membrane devices are connected in series or in parallel may be used.
　生物ろ過装置１０は、ろ材容器１０ａ内に設けられた一層以上のろ過層（１０ｂ，１０ｃ）を有する。ろ過層（１０ｂ，１０ｃ）の層数は、特に限定されず、生物濾過装置１０は任意の層数のろ過層（１０ｂ，１０ｃ）を備えていてもよい。
　一実施形態では、生物膜ろ過装置１０は、ろ材容器１０ａ内に複数のろ過層１０ｂ，１０ｃが鉛直方向に積層された構成を有する。例えば、上層側のろ過層１０ｂのろ材としては、アンスラサイト等のカーボン系材料が用いられ、下層側のろ過層１０ｃとしては、珪砂等の粒状ろ過材が用いられる。これらのろ過層１０ｂ，１０ｃには、生物膜が担持されている。すなわち、微生物が原水中の有機栄養物を利用してろ材表面に生物膜を形成している。
　生物膜ろ過装置１０には、ポンプ１４によって原水（海水）が供給される。生物膜ろ過装置１０の頂部から導入された原水は、ろ過層１０ｂ，１０ｃを通過して下部から排出される。その際、生物膜ろ過装置１０では、ろ過層１０ｂ，１０ｃにより原水中の濁質分（浮遊微粒子）が除去されるとともに、生物膜により原水中の溶存有機物等が分解除去される。
　生物膜ろ過装置１０から排出されたろ過水は、ろ過水タンク１６に貯留された後、ポンプ１８によって逆浸透膜装置１２Ａ，１２Ｂに供給される。
　なお、生物膜ろ過装置１０と逆浸透膜装置１２Ａ，１２Ｂとの間には、例えば限外ろ過膜や精密ろ過膜等の他のろ過装置が設けられていてもよい。 The biological filtration apparatus 10 has one or more filtration layers (10b, 10c) provided in the filter medium container 10a. The number of layers of the filtration layers (10b, 10c) is not particularly limited, and the biological filtration device 10 may include any number of filtration layers (10b, 10c).
In one embodiment, the biofilm filtration device 10 has a configuration in which a plurality of filtration layers 10b and 10c are stacked in the vertical direction in a filter medium container 10a. For example, a carbon-based material such as anthracite is used as the filter medium of the upper filter layer 10b, and a granular filter medium such as silica sand is used as the lower filter layer 10c. A biofilm is supported on the filtration layers 10b and 10c. That is, microorganisms form a biofilm on the filter medium surface using organic nutrients in the raw water.
The biofilm filtration device 10 is supplied with raw water (seawater) by a pump 14. The raw water introduced from the top of the biofilm filtration device 10 passes through the filtration layers 10b and 10c and is discharged from the lower part. At that time, in the biofilm filtration device 10, turbid components (floating fine particles) in the raw water are removed by the filtration layers 10b and 10c, and dissolved organic substances and the like in the raw water are decomposed and removed by the biofilm.
The filtrate discharged from the biological membrane filtration device 10 is stored in the filtrate water tank 16 and then supplied to the reverse osmosis membrane devices 12A and 12B by the pump 18.
Note that another filtration device such as an ultrafiltration membrane or a microfiltration membrane may be provided between the biofilm filtration device 10 and the reverse osmosis membrane devices 12A and 12B.
　第１逆浸透膜装置１２Ａおよび第２逆浸透膜装置１２Ｂは、ろ過層１０ｂ，１０ｃからのろ過水を逆浸透膜によって濃縮水と透過水とに分離するように構成される。
　図示される例では、ろ過水は最初に第１逆浸透膜装置１２Ａに供給され、逆浸透膜によって第１濃縮水と第１透過水とに分離される。このため、第１濃縮水の原水に対する塩濃度比は１より大きくなり、第１透過水の原水に対する塩濃度比は１より小さくなる。
　第１逆浸透膜装置１２Ａで分離された第１濃縮水は第１濃縮水タンク２０Ａに貯留され、第１逆浸透膜装置１２Ａで分離された第１透過水は第２逆浸透膜装置１２Ｂに供給される。
　第２逆浸透膜装置１２Ｂに供給された第１透過水は、逆浸透膜によって第２濃縮水と第２透過水とに分離される。第２濃縮水は、比較的塩濃度比が小さい第１透過水が逆浸透膜によって分離されたものであるため、やはり原水に対する塩濃度比は１より小さくなる。第２透過水の原水に対する塩濃度比は１より小さく、極めて低い塩濃度となっている。第２濃縮水は第２濃縮水タンク２０Ｂに貯留される。
　こうして生成された第２透過水は、後処理を施された後、生産水として利用先に供給される。 The first reverse osmosis membrane device 12A and the second reverse osmosis membrane device 12B are configured to separate filtered water from the filtration layers 10b and 10c into concentrated water and permeated water using a reverse osmosis membrane.
In the illustrated example, filtered water is first supplied to the first reverse osmosis membrane device 12A, and is separated into first concentrated water and first permeated water by the reverse osmosis membrane. For this reason, the salt concentration ratio with respect to the raw water of the 1st concentrated water becomes larger than 1, and the salt concentration ratio with respect to the raw water of the 1st permeated water becomes smaller than 1.
The first concentrated water separated by the first reverse osmosis membrane device 12A is stored in the first concentrated water tank 20A, and the first permeated water separated by the first reverse osmosis membrane device 12A is sent to the second reverse osmosis membrane device 12B. Supplied.
The first permeated water supplied to the second reverse osmosis membrane device 12B is separated into the second concentrated water and the second permeated water by the reverse osmosis membrane. In the second concentrated water, the first permeated water having a relatively small salt concentration ratio is separated by the reverse osmosis membrane, so that the salt concentration ratio with respect to the raw water is also smaller than 1. The salt concentration ratio of the second permeated water to the raw water is smaller than 1, which is a very low salt concentration. The second concentrated water is stored in the second concentrated water tank 20B.
The 2nd permeated water produced | generated in this way is supplied to a user as production water after performing a post-process.
　なお、上述した実施形態では、一例として、生物膜ろ過装置１０が淡水化プラント１に適用された場合について説明したが、本実施形態に係る生物膜ろ過装置１０の適用先は淡水化プラント１に限定されるものではない。すなわち、本実施形態に係る生物膜ろ過装置１０は、少なくとも一つの逆浸透膜装置の上流側に設けられ、生物膜が担持されたろ過層により原水をろ過する構成であればその適用先は特に限定されない。
　この場合、原水とは、塩（例えば塩分）を含む水であって、例えば、海水、地下水、河川、湖沼水、下廃水処理水、または工場排水等であってもよい。上記方法によれば、海水を淡水化したり、下廃水処理水や工場排水等を浄化して再利用水を得たり、河川や湖沼水から上水を生成したりすることができる。 In addition, although embodiment mentioned above demonstrated the case where the biofilm filtration apparatus 10 was applied to the desalination plant 1 as an example, the application destination of the biofilm filtration apparatus 10 which concerns on this embodiment is desalination plant 1 It is not limited. That is, the biofilm filtration device 10 according to the present embodiment is provided on the upstream side of at least one reverse osmosis membrane device, and the application destination thereof is particularly a configuration where raw water is filtered by a filtration layer carrying a biofilm. It is not limited.
In this case, the raw water is water containing salt (for example, salinity), and may be, for example, seawater, groundwater, rivers, lake water, treated wastewater, or factory wastewater. According to the above-described method, seawater can be desalinated, wastewater treated water, factory wastewater, etc. can be purified to obtain reused water, or clean water can be generated from rivers and lakes.
　ここで、上述した生物膜ろ過装置１０とその洗浄方法について詳細に説明する。
　幾つかの実施形態において、生物膜ろ過装置１０は、ろ過層１０ｂ，１０ｃからのろ過水を逆浸透膜で分離して得られる濃縮水を含み、且つ、原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水をろ過層１０ｂ，１０ｃに供給するための逆洗ライン３０をさらに備えている。例えば、逆洗ライン３０は、生物膜ろ過装置１０の底部から逆洗水を供給するようになっている。
　逆洗水として用いられる濃縮水は、第１濃縮水又は第２濃縮水の少なくとも一方を含む。
　そして、生物膜ろ過装置１０では、この逆洗水を用いてろ過層１０ｂ，１０ｃを逆洗し、ろ過層１０ｂ，１０ｃ（特に上層側のろ過層１０ｂ）に付着した濁質分を除去する。 Here, the biofilm filtration apparatus 10 mentioned above and its washing | cleaning method are demonstrated in detail.
In some embodiments, the biofilm filtration device 10 includes concentrated water obtained by separating filtered water from the filtration layers 10b and 10c with a reverse osmosis membrane, and is 0.6 or more and 1 with respect to raw water. A backwash line 30 is further provided for supplying backwash water having a salt concentration ratio of .5 or less to the filtration layers 10b and 10c. For example, the backwash line 30 is configured to supply backwash water from the bottom of the biofilm filtration device 10.
The concentrated water used as the backwash water includes at least one of the first concentrated water and the second concentrated water.
And in the biofilm filtration apparatus 10, the filtration layers 10b and 10c are backwashed using this backwash water, and the turbid matter adhering to the filtration layers 10b and 10c (especially the upper filtration layer 10b) is removed.
　この方法によれば、ろ過層１０ｂ，１０ｃの洗浄に際して、ろ過層１０ｂ，１０ｃの後段に設けられた逆浸透膜装置１２Ａ，１２Ｂで分離して得られる濃縮水（第１濃縮水又は第２濃縮水の少なくとも一方を含む）を用いるようにしている。通常、濃縮水は廃棄されることが多いため、この濃縮水を逆洗水として用いることで生産水の生成プロセス中の水を多量に引き抜いて利用する必要がなくなり、生産効率の低下を回避できる。また、系内の水を有効利用することができるため、外部から逆洗水を調達する場合に比べてコストの削減効果も大きい。 According to this method, when the filtration layers 10b and 10c are washed, the concentrated water (first concentrated water or second concentrated water) obtained by separation with the reverse osmosis membrane devices 12A and 12B provided at the subsequent stage of the filtration layers 10b and 10c. Including at least one of water). Normally, concentrated water is often discarded, so using this concentrated water as backwash water eliminates the need to draw out a large amount of water in the production water production process and avoids a decrease in production efficiency. . In addition, since the water in the system can be used effectively, the cost reduction effect is great compared to the case where backwash water is procured from the outside.
　ところで、逆浸透膜で分離された濃縮水は、原水とは塩濃度が相違する。例えば、生物膜ろ過装置１０のろ過水が供給される第１逆浸透膜装置１２Ａの場合、逆浸透膜で分離された第１濃縮水は原水よりも塩濃度が高くなる。一方、第２逆浸透膜装置１２Ｂで分離された第２濃縮水は、上流側の第１逆浸透膜装置１２Ａで得られる透過水を分離したものであるため原水よりも塩濃度が低くなる。このように、原水とは塩濃度が異なる濃縮水を逆洗水として利用すると、ろ過層１０ｂ，１０ｃに担持された微生物周囲の塩濃度環境が変化し、浸透圧差によって微生物の細胞内外での液の移動が起こって微生物の活性が大幅に低下する可能性がある。 By the way, the concentrated water separated by the reverse osmosis membrane has a salt concentration different from that of the raw water. For example, in the case of the first reverse osmosis membrane device 12A to which the filtered water of the biofilm filtration device 10 is supplied, the first concentrated water separated by the reverse osmosis membrane has a higher salt concentration than the raw water. On the other hand, the second concentrated water separated by the second reverse osmosis membrane device 12B is obtained by separating the permeated water obtained by the upstream first reverse osmosis membrane device 12A, and therefore has a lower salt concentration than the raw water. In this way, when concentrated water having a salt concentration different from that of the raw water is used as backwash water, the salt concentration environment around the microorganisms supported on the filtration layers 10b and 10c changes, and the liquid inside and outside the microorganisms due to the difference in osmotic pressure. Migration may occur and the activity of microorganisms may be significantly reduced.
　そこで、本発明者らは、鋭意検討の結果、図５に示すように原水中の微生物の活性と塩濃度との間の相関関係を見出した。すなわち、原水に対する塩濃度比が０．６以上且つ１．５以下の環境下において、微生物の活性を適正に維持できることがわかった。なお、図５は、微生物の生存率（活性）と塩濃度比との相関関係を示すグラフである。
　図５に示すように、原水に対する塩濃度比が０．６以上且つ１．５以下の環境下では、微生物の生存率は略５０％以上を維持する。一般的な逆洗間隔と微生物の増殖率を考慮したとき、微生物の生存率が略５０％以上であれば、次回の逆洗時間までに微生物の生存率は十分に回復し、濃縮水を含む逆洗水を用いた逆洗によって微生物が減少し続けることを回避できる。 As a result of intensive studies, the present inventors have found a correlation between the activity of microorganisms in the raw water and the salt concentration, as shown in FIG. That is, it was found that the activity of microorganisms can be properly maintained in an environment where the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less. FIG. 5 is a graph showing the correlation between the survival rate (activity) of microorganisms and the salt concentration ratio.
As shown in FIG. 5, in an environment where the salt concentration ratio to the raw water is 0.6 or more and 1.5 or less, the survival rate of the microorganisms is maintained at about 50% or more. When considering the general backwash interval and the growth rate of microorganisms, if the survival rate of microorganisms is approximately 50% or more, the survival rate of microorganisms will be sufficiently recovered by the next backwash time, and it will contain concentrated water. It can be avoided that microorganisms continue to decrease by backwashing using backwashing water.
　なお、本発明者らは、海水中の微生物の培養試験を行い、その試験結果（図６参照）に基づいて、微生物の生存率が略５０％以上のとき、濃縮水を含む逆洗水を用いた逆洗を行っても微生物の活性を維持し続けるという知見を得た。図６は培養時間とＳＳ濃度（海水中の懸濁物質の濃度）との関係を示すグラフである。
　一般に微生物の増殖速度は以下の式で定義される。
　　μ／２．３０３×（ｔ－ｔ０）＝ｌｏｇ１０Ｚ－ｌｏｇ１０Ｚ０
　ここで、μ：比増殖速度［ｈ－１］、ｔ：時間、Ｚ：細胞量／ｍｌである。
　また、細胞量が２倍になる倍加時間（ｇ）は以下の式で定義される。
　　μ＝ｌｎ２／ｇ
　　ｇ＝ｌｎ２／μ
　これらの式を用いて、図６に示す試験結果から、海水中の微生物の倍加時間は約４時間となる。一方、一般的な逆洗間隔は４時間以上であるため、微生物の生存率が略５０％以上であれば次回の逆洗までに微生物が十分に回復することが明らかとなった。 The present inventors conducted a culture test for microorganisms in seawater, and based on the test results (see FIG. 6), when the survival rate of microorganisms was approximately 50% or more, backwash water containing concentrated water was used. It was found that the activity of microorganisms was maintained even after backwashing was used. FIG. 6 is a graph showing the relationship between culture time and SS concentration (concentration of suspended solids in seawater).
In general, the growth rate of microorganisms is defined by the following equation.
μ / 2.303 × (t−t 0 ) = log 10 Z-log 10 Z 0
Here, μ: specific growth rate [h −1 ], t: time, Z: cell amount / ml.
The doubling time (g) for doubling the cell volume is defined by the following equation.
μ = ln2 / g
g = ln2 / μ
Using these equations, the doubling time of microorganisms in seawater is about 4 hours from the test results shown in FIG. On the other hand, since the general backwashing interval is 4 hours or more, it has been clarified that the microorganisms are sufficiently recovered by the next backwashing if the survival rate of the microorganisms is approximately 50% or more.
　したがって、上記方法によれば、原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を用いてろ過層１０ｂ，１０ｃを逆洗することで、ろ過層１０ｂ，１０ｃに担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。このため、上述したように生産効率およびコスト面から有利な濃縮水を逆洗水として有効利用することが可能となる。 Therefore, according to the above method, the filtration layers 10b and 10c are backwashed by using the backwash water having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water. The activity of the microorganisms can be maintained to such an extent that the function of biological treatment by the microorganisms supported by the microorganisms can be sufficiently exerted. For this reason, as described above, it is possible to effectively use the concentrated water, which is advantageous in terms of production efficiency and cost, as the backwash water.
　また、逆洗水は、原水に対して０．８以上且つ１．２５以下の塩濃度比を有していてもよい。
　これによれば、濃縮水の供給による微生物の活性低下をより効果的に抑制でき、生物膜ろ過装置１０による生物処理機能をより適正に維持できる。また、逆洗後に通常運転を再開した際、微生物が通常の活性に戻るまでの時間を短くすることができる。 The backwash water may have a salt concentration ratio of 0.8 or more and 1.25 or less with respect to the raw water.
According to this, the activity reduction of the microorganisms by supply of concentrated water can be suppressed more effectively, and the biological treatment function by the biofilm filtration apparatus 10 can be maintained more appropriately. Moreover, when normal operation is resumed after backwashing, the time until the microorganisms return to normal activity can be shortened.
　ろ過層１０ｂ，１０ｃの逆洗時間は、５分以上３０分以内であってもよい。または、ろ過層１０ｂ，１０ｃの逆洗時間は、１０分以上２０分以内であってもよい。
　これによれば、ろ過層の逆洗時間を５分以上３０分以内とすることによって、微生物の活性を適正に維持しながら、ろ過層１０ｂ，１０ｃに付着した濁質分を適切に除去することができる。 The backwash time of the filtration layers 10b and 10c may be 5 minutes or more and 30 minutes or less. Alternatively, the backwash time of the filtration layers 10b and 10c may be 10 minutes or more and 20 minutes or less.
According to this, by making the backwash time of the filtration layer 5 minutes or more and 30 minutes or less, the turbid matter adhering to the filtration layers 10b and 10c is appropriately removed while appropriately maintaining the activity of the microorganisms. Can do.
　生物膜ろ過装置１０は、運転中、凝集剤等の薬品が添加されていない原水をろ過してろ過水を生成するように構成されてもよい。すなわち、生物膜ろ過装置１０は無薬注前処理を行うように構成されてもよい。
　これによれば、原水に対して凝集剤等の薬品を添加することによる環境負荷を軽減するために、無薬注前処理を行うようにした生物膜ろ過装置１０においても、上述した構成を備えることによって、低コストで且つ適切な逆洗を行うことが可能となる。 The biofilm filtration device 10 may be configured to filter raw water to which chemicals such as a flocculant are not added during operation to generate filtered water. That is, the biofilm filtration device 10 may be configured to perform a pre-drug pretreatment.
According to this, in order to reduce the environmental load caused by adding chemicals such as a flocculant to the raw water, the biofilm filtration apparatus 10 configured to perform the pre-drug pretreatment also has the above-described configuration. This makes it possible to perform appropriate backwashing at low cost.
　次に、各実施形態に係る生物膜ろ過装置１０の具体的な構成について説明する。 Next, a specific configuration of the biofilm filtration device 10 according to each embodiment will be described.
　図１は、第１実施形態に係る生物膜ろ過装置１０を示す構成図である。
　同図に示すように、第１実施形態に係る生物膜ろ過装置１０は、第１逆浸透膜装置１２Ａで分離された第１濃縮水を含む逆洗水によって、ろ過層１０ｂ，１０ｃの逆洗を行うように構成される。 FIG. 1 is a configuration diagram illustrating a biofilm filtration device 10 according to the first embodiment.
As shown in the figure, the biofilm filtration device 10 according to the first embodiment is configured to backwash the filtration layers 10b and 10c with backwash water containing the first concentrated water separated by the first reverse osmosis membrane device 12A. Configured to do.
　第１逆浸透膜装置１２は、第１濃縮水を含む逆洗水をろ過層１０ｂ，１０ｃに供給するための逆洗ライン３０を備えており、この逆洗ライン３０から供給する逆洗水の原水に対する塩濃度比を０．６以上且つ１．５以下、または０．８以上且つ１．２５以下としている。
　逆洗水が貯留される逆洗水タンク３２には、第１濃縮水タンク２０Ａからの第１濃縮水が供給されるようになっている。第１濃縮水タンク２０Ａから逆洗水タンク３２への第１濃縮水の供給量はバルブ３４により調節される。
　そして、逆洗水タンク３２に貯留された逆洗水（第１濃縮水）は、生物膜ろ過装置１０の逆洗時、逆洗水ライン３０を介してろ過層１０ｂ，１０ｃに供給される。 The first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water containing the first concentrated water to the filtration layers 10 b and 10 c, and backwash water supplied from the backwash line 30. The salt concentration ratio to the raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
The first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored. The supply amount of the first concentrated water from the first concentrated water tank 20 </ b> A to the backwash water tank 32 is adjusted by a valve 34.
And the backwash water (1st concentrated water) stored in the backwash water tank 32 is supplied to the filtration layers 10b and 10c via the backwash water line 30 at the time of the backwashing of the biofilm filtration apparatus 10.
　これにより、原水とは異なる塩濃度を有する第１濃縮水を逆洗水として用いても、ろ過層に担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。したがって、第１濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　なお、図示される例では、第１濃縮水を逆洗水として用いた場合を示したが、第２濃縮水を逆洗水として用いてもよい。 Thereby, even if the 1st concentrated water which has a salt concentration different from raw | natural water is used as backwash water, the activity of microorganisms is maintained to such an extent that the function of the biological treatment by the microorganisms supported by the filtration layer can be sufficiently exhibited. be able to. Therefore, it is possible to use the first concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
In the illustrated example, the case where the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
　図２は、第２実施形態に係る生物膜ろ過装置１０を示す構成図である。
　同図に示すように、第２実施形態に係る生物膜ろ過装置１０は、第１逆浸透膜装置１２Ａで分離された第１濃縮水と、生物膜ろ過装置１０でろ過されたろ過水とを含む逆洗水によって、ろ過層１０ｂ，１０ｃの逆洗を行うように構成される。 FIG. 2 is a configuration diagram showing the biofilm filtration device 10 according to the second embodiment.
As shown in the figure, the biofilm filtration device 10 according to the second embodiment includes the first concentrated water separated by the first reverse osmosis membrane device 12A and the filtered water filtered by the biofilm filtration device 10. It comprises so that the backwashing of the filtration layers 10b and 10c may be performed by the backwash water contained.
　第１逆浸透膜装置１２は、第１濃縮水およびろ過水を含む逆洗水をろ過層１０ｂ，１０ｃに供給するための逆洗ライン３０を備えており、この逆洗ライン３０から供給する逆洗水の原水に対する塩濃度比を０．６以上且つ１．５以下、または０．８以上且つ１．２５以下としている。
　逆洗水が貯留される逆洗水タンク３２には、第１濃縮水タンク２０Ａからの第１濃縮水が供給されるようになっている。第１濃縮水タンク２０Ａから逆洗水タンク３２への第１濃縮水の供給量はバルブ３４により調節される。また、逆洗水タンク３２には、ろ過水タンク１６からのろ過水も供給されるようになっている。ろ過水タンク１６から逆洗水タンク３２へのろ過水の供給量はバルブ３６により調節される。これらのバルブ３４，３６を制御することによって、逆洗水の塩濃度比を上記範囲に調整してもよい。
　そして、逆洗水タンク３２に貯留された逆洗水（第１濃縮水およびろ過水の混合水）は、生物膜ろ過装置１０の逆洗時、逆洗水ラインを介してろ過層１０ｂ，１０ｃに供給される。
　なお、図示される例では、第１濃縮水を逆洗水として用いた場合を示したが、第２濃縮水を逆洗水として用いてもよい。 The first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water including the first concentrated water and filtered water to the filtration layers 10b and 10c. The salt concentration ratio of the washing water to the raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
The first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored. The supply amount of the first concentrated water from the first concentrated water tank 20 </ b> A to the backwash water tank 32 is adjusted by a valve 34. The backwash water tank 32 is also supplied with filtered water from the filtered water tank 16. The supply amount of filtrate water from the filtrate water tank 16 to the backwash water tank 32 is adjusted by a valve 36. By controlling these valves 34 and 36, the salt concentration ratio of the backwash water may be adjusted to the above range.
The backwash water (mixed water of the first concentrated water and the filtered water) stored in the backwash water tank 32 is filtered through the backwash water line when the biofilm filtration device 10 is backwashed. To be supplied.
In the illustrated example, the case where the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
　これによれば、第１濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　さらに、逆洗水にろ過水を混合させることで、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上述した塩濃度比の範囲に容易に調整することができる。なお、逆洗水としてろ過水のみを用いる場合に比べて、濁質分を殆ど含まない濃縮水をろ過水と混合して利用することによって、濁質分によるろ過層の汚染を抑制できる。 According to this, it becomes possible to use the 1st concentrated water for backwashing, the fall of production efficiency by backwashing can be prevented, and reduction of processing cost can be aimed at.
Furthermore, by mixing the filtered water with the backwash water, the salt concentration of the concentrated water can be brought close to the raw water, and the backwash water can be easily adjusted to the above-described salt concentration ratio range. In addition, compared with the case where only filtered water is used as backwash water, contamination of the filtration layer due to turbid components can be suppressed by using concentrated water containing almost no turbid components mixed with filtered water.
　図３は、第３実施形態に係る生物膜ろ過装置１０を示す構成図である。
　同図に示すように、第２実施形態に係る生物膜ろ過装置１０は、第１逆浸透膜装置１２Ａで分離された第１濃縮水と、原水とを含む逆洗水によって、ろ過層１０ｂ，１０ｃの逆洗を行うように構成される。 FIG. 3 is a configuration diagram showing the biofilm filtration device 10 according to the third embodiment.
As shown in the figure, the biofilm filtration device 10 according to the second embodiment includes a filtration layer 10b, by backwash water containing the first concentrated water separated by the first reverse osmosis membrane device 12A and raw water. 10c is configured to perform backwashing.
　第１逆浸透膜装置１２は、第１濃縮水および原水を含む逆洗水をろ過層１０ｂ，１０ｃに供給するための逆洗ライン３０を備えており、この逆洗ライン３０から供給する逆洗水の原水に対する塩濃度比を０．６以上且つ１．５以下、または０．８以上且つ１．２５以下としている。
　逆洗水が貯留される逆洗水タンク３２には、第１濃縮水タンク２０Ａからの第１濃縮水が供給されるようになっている。第１濃縮水タンク２０Ａから逆洗水タンク３２への第１濃縮水の供給量はバルブ３４により調節される。また、逆洗水タンク３２には、原水タンク（不図示）からの原水も供給されるようになっている。逆洗水タンク３２への原水の供給量はバルブ３８により調節される。これらのバルブ３４，３８を制御することによって、逆洗水の塩濃度比を上記範囲に調整してもよい。
　そして、逆洗水タンク３２に貯留された逆洗水（第１濃縮水および原水の混合水）は、生物膜ろ過装置１０の逆洗時、逆洗水ラインを介してろ過層１０ｂ，１０ｃに供給される。
　なお、図示される例では、第１濃縮水を逆洗水として用いた場合を示したが、第２濃縮水を逆洗水として用いてもよい。 The first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water including the first concentrated water and raw water to the filtration layers 10 b and 10 c, and the backwash supplied from the backwash line 30. The salt concentration ratio of water to raw water is 0.6 or more and 1.5 or less, or 0.8 or more and 1.25 or less.
The first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored. The supply amount of the first concentrated water from the first concentrated water tank 20 </ b> A to the backwash water tank 32 is adjusted by a valve 34. The backwash water tank 32 is also supplied with raw water from a raw water tank (not shown). The amount of raw water supplied to the backwash water tank 32 is adjusted by a valve 38. By controlling these valves 34 and 38, the salt concentration ratio of the backwash water may be adjusted to the above range.
Then, the backwash water (mixed water of the first concentrated water and the raw water) stored in the backwash water tank 32 is supplied to the filtration layers 10b and 10c via the backwash water line when the biofilm filtration device 10 is backwashed. Supplied.
In the illustrated example, the case where the first concentrated water is used as the backwash water is shown, but the second concentrated water may be used as the backwash water.
　これによれば、第１濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　さらに、逆洗水に原水を混合させることで、濃縮水の塩濃度を原水に近づけることができ、逆洗水を上述した塩濃度比の範囲に容易に調整することができる。なお、逆洗水としてろ過水のみを用いる場合に比べて、濁質分を殆ど含まない濃縮水をろ過水と混合して利用することによって、濁質分によるろ過層の汚染を抑制できる。 According to this, it becomes possible to use the 1st concentrated water for backwashing, the fall of production efficiency by backwashing can be prevented, and reduction of processing cost can be aimed at.
Furthermore, by mixing the raw water with the backwash water, the salt concentration of the concentrated water can be brought close to the raw water, and the backwash water can be easily adjusted to the above-described salt concentration ratio range. In addition, compared with the case where only filtered water is used as backwash water, contamination of the filtration layer due to turbid components can be suppressed by using concentrated water containing almost no turbid components mixed with filtered water.
　図４は、第４実施形態に係る生物膜ろ過装置１０を示す構成図である。
　同図に示すように、第４実施形態に係る生物膜ろ過装置１０は、第１逆浸透膜装置１２Ａで分離された第１濃縮水と、第２逆浸透膜装置１２Ｂで分離された第２濃縮水とを含む逆洗水によって、ろ過層１０ｂ，１０ｃの逆洗を行うように構成される。 FIG. 4 is a configuration diagram showing the biofilm filtration device 10 according to the fourth embodiment.
As shown in the figure, the biofilm filtration device 10 according to the fourth embodiment includes a first concentrated water separated by the first reverse osmosis membrane device 12A and a second separated by the second reverse osmosis membrane device 12B. The backwashing water containing concentrated water is configured to backwash the filtration layers 10b and 10c.
　第１逆浸透膜装置１２は、第１濃縮水および第２濃縮水を含む逆洗水をろ過層１０ｂ，１０ｃに供給するための逆洗ライン３０を備えており、この逆洗ライン３０から供給する逆洗水の原水に対する塩濃度比を０．６以上且つ１．５以下、または０．８以上且つ１．２５以下としている。
　逆洗水が貯留される逆洗水タンク３２には、第１濃縮水タンク２０Ａからの第１濃縮水が供給されるようになっている。第１濃縮水タンク２０Ａから逆洗水タンク３２への第１濃縮水の供給量はバルブ３４により調節される。また、逆洗水タンク３２には、第２濃縮水タンク２０Ｂからの第２濃縮水も供給されるようになっている。第２濃縮水タンク２０Ｂから逆洗水タンク３２への第２濃縮水の供給量はバルブ４０により調節される。これらのバルブ３４，４０を制御することによって、逆洗水の塩濃度比を上記範囲に調整してもよい。
　そして、逆洗水タンク３２に貯留された逆洗水（第１濃縮水および第２濃縮水の混合水）は、生物膜ろ過装置１０の逆洗時、逆洗水ラインを介してろ過層１０ｂ，１０ｃに供給される。 The first reverse osmosis membrane device 12 includes a backwash line 30 for supplying backwash water containing the first concentrated water and the second concentrated water to the filtration layers 10 b and 10 c, and is supplied from the backwash line 30. The salt concentration ratio of the backwash water to the raw water is 0.6 to 1.5, or 0.8 to 1.25.
The first concentrated water from the first concentrated water tank 20A is supplied to the backwash water tank 32 in which the backwash water is stored. The supply amount of the first concentrated water from the first concentrated water tank 20 </ b> A to the backwash water tank 32 is adjusted by a valve 34. The backwash water tank 32 is also supplied with the second concentrated water from the second concentrated water tank 20B. The supply amount of the second concentrated water from the second concentrated water tank 20 </ b> B to the backwash water tank 32 is adjusted by the valve 40. By controlling these valves 34 and 40, the salt concentration ratio of the backwash water may be adjusted to the above range.
The backwash water (mixed water of the first concentrated water and the second concentrated water) stored in the backwash water tank 32 is filtered through the backwash water line when the biofilm filtration device 10 is backwashed. , 10c.
　これによれば、第１濃縮水および第２濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。
　さらに、高塩濃度の第１濃縮水と低塩濃度の第２濃縮水を混合させることで、生産効率およびコスト面から有利な濃縮水を用いて、上述した塩濃度比の逆洗水を生成することができる。 According to this, it becomes possible to use the 1st concentrated water and the 2nd concentrated water for backwashing, the fall of the production efficiency by backwashing can be prevented, and the reduction of processing cost can be aimed at.
Further, by mixing the first concentrated water having a high salt concentration and the second concentrated water having a low salt concentration, the backwash water having the above-mentioned salt concentration ratio is generated using concentrated water advantageous in terms of production efficiency and cost. can do.
　なお、上述した第１～第４実施形態において、濃縮水に対して、系外から供給される水を混合させることで逆洗水の原水に対する塩濃度比を上述した範囲に調整してもよい。 In the first to fourth embodiments described above, the salt concentration ratio with respect to the raw water of the backwash water may be adjusted to the above-described range by mixing water supplied from outside the system with the concentrated water. .
　上述したように、本発明の少なくとも幾つかの実施形態によれば、濃縮水を含み、且つ、原水に対する塩濃度比が０．６以上且つ１．５である逆洗水を用いてろ過層１０ｂ，１０ｃの逆洗を行うようにしたので、原水とは異なる塩濃度を有する濃縮水を逆洗水として用いても、ろ過層１０ｂ，１０ｃに担持された微生物による生物処理の機能を十分に発揮し得る程度に微生物の活性を維持することができる。したがって、濃縮水を逆洗に用いることが可能となり、逆洗による生産効率の低下を防止でき、また処理コストの削減が図れる。 As described above, according to at least some embodiments of the present invention, the filtration layer 10b is formed using backwash water containing concentrated water and having a salt concentration ratio of 0.6 or more and 1.5 with respect to raw water. , 10c is backwashed, so that even when concentrated water having a salt concentration different from that of the raw water is used as backwash water, the biological treatment function by the microorganisms supported by the filtration layers 10b, 10c is fully exhibited. The activity of the microorganism can be maintained to the extent possible. Therefore, it is possible to use concentrated water for backwashing, preventing a reduction in production efficiency due to backwashing, and reducing processing costs.
　本発明は上述した実施形態に限定されることはなく、上述した実施形態に変形を加えた形態や、これらの形態を適宜組み合わせた形態も含む。 The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
　例えば、「同一」、「等しい」及び「均質」等の物事が等しい状態であることを表す表現は、厳密に等しい状態を表すのみならず、公差、若しくは、同じ機能が得られる程度の差が存在している状態も表すものとする。
　また、一の構成要素を「備える」、「含む」、又は、「有する」という表現は、他の構成要素の存在を除外する排他的な表現ではない。 For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
In addition, the expression “comprising”, “including”, or “having” one constituent element is not an exclusive expression for excluding the existence of another constituent element.
１　　　淡水化プラント
１０　　生物膜ろ過装置
１０ａ　ろ材容器
１０ｂ　ろ過層
１０ｃ　ろ過層
１２Ａ　第１逆浸透膜装置
１２Ｂ　第２逆浸透膜装置
１６　　ろ過水タンク
２０Ａ　第１濃縮水タンク
２０Ｂ　第２濃縮水タンク
３０　　逆洗ライン
３２　　逆洗水タンク
  DESCRIPTION OF SYMBOLS 1 Desalination plant 10 Biomembrane filtration apparatus 10a Filter medium container 10b Filtration layer 10c Filtration layer 12A 1st reverse osmosis membrane apparatus 12B 2nd reverse osmosis membrane apparatus 16 Filtrated water tank 20A 1st concentrated water tank 20B 2nd concentrated water tank 30 reverse Wash line 32 Backwash tank

Claims (13)

  1. 　生物膜が担持されたろ過層により原水をろ過する生物膜ろ過装置のろ過層洗浄方法であって、
    　前記ろ過層からのろ過水を逆浸透膜で分離して得られる濃縮水を含み、且つ、前記原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を用いて、前記ろ過層を逆洗することを特徴とするろ過層洗浄方法。     A method for cleaning a filtration layer of a biofilm filtration device for filtering raw water through a filtration layer carrying a biofilm,
    Using concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and using backwash water having a salt concentration ratio of 0.6 or more and 1.5 or less with respect to the raw water The filtration layer washing | cleaning method characterized by backwashing the said filtration layer.
  2. 　前記逆洗水は、前記原水に対して０．８以上且つ１．２５以下の塩濃度比を有することを特徴とする請求項１に記載のろ過層洗浄方法。 The filtration layer cleaning method according to claim 1, wherein the backwash water has a salt concentration ratio of 0.8 or more and 1.25 or less with respect to the raw water.
  3. 　前記逆洗水は、前記逆浸透膜に供給される前の前記ろ過水をさらに含むことを特徴とする請求項１又は２に記載のろ過層洗浄方法。 The filtration layer cleaning method according to claim 1 or 2, wherein the backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
  4. 　前記逆洗水は、前記原水をさらに含むことを特徴とする請求項１乃至３の何れか一項に記載のろ過層洗浄方法。 The filtration layer cleaning method according to any one of claims 1 to 3, wherein the backwash water further includes the raw water.
  5. 　前記逆浸透膜が、直列に接続された第１逆浸透膜および第２逆浸透膜を含み、
    　前記逆洗水は、前記第１逆浸透膜で分離された第１濃縮水、または、前記第２逆浸透膜で分離された第２濃縮水の少なくとも一方を含むことを特徴とする請求項１乃至４の何れか一項に記載のろ過層洗浄方法。     The reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series,
    The backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane and second concentrated water separated by the second reverse osmosis membrane. The filtration layer washing | cleaning method as described in any one of thru | or 4.
  6. 　前記ろ過層の逆洗時間は、５分以上３０分以内であることを特徴とする請求項１乃至５の何れか一項に記載のろ過層洗浄方法。 The filtration layer cleaning method according to any one of claims 1 to 5, wherein the backwash time of the filtration layer is 5 minutes or more and 30 minutes or less.
  7. 　生物膜が担持され、原水をろ過するように構成されたろ過層と、
    　前記ろ過層からのろ過水を逆浸透膜で分離して得られる濃縮水を含み、且つ、前記原水に対して０．６以上且つ１．５以下の塩濃度比を有する逆洗水を前記ろ過層に供給するための逆洗ラインと、
    を備えることを特徴とする生物膜ろ過装置。     A filtration layer supported by a biofilm and configured to filter raw water;
    Containing concentrated water obtained by separating filtered water from the filtration layer with a reverse osmosis membrane, and filtering backwash water having a salt concentration ratio of 0.6 to 1.5 with respect to the raw water A backwash line to supply the bed,
    A biofilm filtration device comprising:
  8. 　前記逆洗水は、前記原水に対して０．８以上且つ１．２５以下の塩濃度比を有することを特徴とする請求項７に記載の生物膜ろ過装置。 The biofilm filtration device according to claim 7, wherein the backwash water has a salt concentration ratio of 0.8 to 1.25 with respect to the raw water.
  9. 　前記逆洗水は、前記逆浸透膜に供給される前の前記ろ過水をさらに含むことを特徴とする請求項７又は８に記載の生物膜ろ過装置。 The biofilm filtration device according to claim 7 or 8, wherein the backwash water further includes the filtered water before being supplied to the reverse osmosis membrane.
  10. 　前記逆洗水は、前記原水をさらに含むことを特徴とする請求項７乃至９の何れか一項に記載の生物膜ろ過装置。 The biofilm filtration device according to any one of claims 7 to 9, wherein the backwash water further includes the raw water.
  11. 　前記逆浸透膜が、直列に接続された第１逆浸透膜および第２逆浸透膜を含み、
    　前記逆洗水は、前記第１逆浸透膜で分離された第１濃縮水、または、前記第２逆浸透膜で分離された第２濃縮水の少なくとも一方を含むことを特徴とする請求項７乃至１０の何れか一項に記載の生物膜ろ過装置。     The reverse osmosis membrane includes a first reverse osmosis membrane and a second reverse osmosis membrane connected in series,
    The backwash water includes at least one of first concentrated water separated by the first reverse osmosis membrane and second concentrated water separated by the second reverse osmosis membrane. The biofilm filtration apparatus as described in any one of thru | or 10.
  12. 　前記生物膜ろ過装置は、前記生物膜ろ過装置の運転中、薬品が添加されていない前記原水をろ過して前記ろ過水を生成するように構成されたことを特徴とする請求項７乃至１１の何れか一項に記載の生物膜ろ過装置。 12. The biofilm filtration device according to claim 7, wherein the biofilm filtration device is configured to filter the raw water to which the chemical is not added to generate the filtered water during operation of the biofilm filtration device. The biofilm filtration device according to any one of the above.
  13. 　請求項７乃至１２の何れか一項に記載の生物膜ろ過装置と、
    　前記生物膜ろ過装置の下流側に位置し、前記ろ過層からのろ過水を逆浸透膜によって前記濃縮水と透過水とに分離するように構成された少なくとも一つの逆浸透膜装置と、
    を備えることを特徴とする淡水化プラント。
          The biofilm filtration device according to any one of claims 7 to 12,
    At least one reverse osmosis membrane device located downstream of the biofilm filtration device and configured to separate filtered water from the filtration layer into the concentrated water and permeated water by a reverse osmosis membrane;
    A desalination plant comprising:
PCT/JP2016/060810 2016-03-31 2016-03-31 Filtration layer cleaning method, biological membrane filtration apparatus, and desalination plant WO2017168721A1 (en)

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Publication number Priority date Publication date Assignee Title
JPH0679272A (en) * 1992-09-02 1994-03-22 Kurita Water Ind Ltd Device for production of pure water
JP2012239948A (en) * 2011-05-17 2012-12-10 Toray Ind Inc Method for washing filter medium, and water treatment apparatus
WO2013125373A1 (en) * 2012-02-21 2013-08-29 東レ株式会社 Water treatment device and water treatment method
JP2013188690A (en) * 2012-03-14 2013-09-26 Toshiba Corp Membrane filtration system
JP2013202548A (en) * 2012-03-29 2013-10-07 Swing Corp Desalination device and desalination method
WO2014007262A1 (en) * 2012-07-02 2014-01-09 東レ株式会社 Fresh-water manufacturing device and fresh-water manufacturing method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0679272A (en) * 1992-09-02 1994-03-22 Kurita Water Ind Ltd Device for production of pure water
JP2012239948A (en) * 2011-05-17 2012-12-10 Toray Ind Inc Method for washing filter medium, and water treatment apparatus
WO2013125373A1 (en) * 2012-02-21 2013-08-29 東レ株式会社 Water treatment device and water treatment method
JP2013188690A (en) * 2012-03-14 2013-09-26 Toshiba Corp Membrane filtration system
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