JP2015054273A - Desalination system - Google Patents

Desalination system Download PDF

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Publication number
JP2015054273A
JP2015054273A JP2013188031A JP2013188031A JP2015054273A JP 2015054273 A JP2015054273 A JP 2015054273A JP 2013188031 A JP2013188031 A JP 2013188031A JP 2013188031 A JP2013188031 A JP 2013188031A JP 2015054273 A JP2015054273 A JP 2015054273A
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water
treated
filter
pressure increase
desalination
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Inventor
みさき 隅倉
Misaki Sumikura
みさき 隅倉
利昭 荒戸
Toshiaki Arato
利昭 荒戸
晃治 陰山
Koji Kageyama
晃治 陰山
隆広 舘
Takahiro Tachi
隆広 舘
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株式会社日立製作所
Hitachi Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124Water desalination
    • Y02A20/131Reverse-osmosis
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

Abstract

【Task】
The present invention provides a desalination system that is highly responsive to fluctuations in the quality of the water to be treated and that suppresses biofouling generation and enables stable operation.
[Solution]
In the desalination system 100, the water to be treated into which the flocculant has been injected flows, and the biological treatment device 14 that holds microorganisms that assimilate organic matter in the water to be treated and the water to be treated flowing out from the biological treatment device 14 are contaminated. A pretreatment unit comprising a filter 16 for removing substances, and a reverse osmosis membrane module 18 for separating water to be treated flowing out from the filter 16 into permeated water 6 from which salt is removed and concentrated water 7 from which salt is concentrated; The pressure gauge 15 that measures the pressure of the water to be treated flowing into the filter 16 and the control device 8 that controls the pretreatment unit based only on the pressure of the water to be treated that flows into the filter 16 measured by the pressure gauge 15. Have
[Selection] Figure 1

Description

  The present invention relates to a desalination system using a reverse osmosis membrane that obtains fresh water from seawater or brine.

  In a desalination system using a reverse osmosis membrane, reduction of freshwater production efficiency and deterioration of product water quality due to contamination of the reverse osmosis membrane are problems. Factors that cause membrane contamination include particulate matter, precipitated inorganic compounds, sticky organic matter, and biofilms (biofilms) derived from metabolites of grown marine bacteria. In particular, an occlusive substance in which an organic substance and a biofilm are mixed is called biofouling, and its suppression is required.

  Various pretreatment technologies have been developed to remove these contamination factors from the treated water supplied to the reverse osmosis membrane. Examples include single-layer and multi-layer sand filtration devices, precision membranes, and ultra-membranes. A filtration device using is introduced. The purpose of pre-treatment has been mainly to remove turbid components that physically block the membrane, but when aiming to suppress the formation of biofouling, in addition to removing turbid components, microorganisms can serve as nutrient sources. It is also required to remove components that are easy to use, that is, biodegradable components. These biodegradable components are mainly soluble components.

  As a pretreatment for a desalination system, introduction of a biological treatment apparatus that removes this biodegradable component by microorganisms is also being studied. In a biological treatment apparatus, a filter medium or a carrier carrying microorganisms on its surface is fixed to a filling container or a contact tank or floated. Microorganisms take in biodegradable components in the water to be treated, proliferate and discharge polysaccharides outside the body, so that biofilms grow.

  Japanese Patent Laid-Open No. 7-60241 (Patent Document 1) discloses a biological treatment apparatus. In patent document 1, biological activated carbon is used for the pretreatment facility for seawater desalination, a safety filter is installed at the subsequent stage, and an ultraviolet irradiation device is provided between the biological activated carbon and the safety filter. Thereby, the injection | pouring of an oxidizing agent and a reducing agent is made unnecessary by disinfecting the organism which flowed out from biological activated carbon.

  Japanese Patent Application Laid-Open No. 2009-195818 (Patent Document 2), which relates to water purification, injects a flocculant into water to be treated and filters it with a membrane module having a precision membrane or an ultra membrane. . Then, the water quality of the treated water before injecting the flocculant, the inflow side pressure and the outflow side pressure of the membrane module are measured, and the injection rate of the flocculant and the membrane module are determined based on the water quality of the treated water and the differential pressure of the membrane module. Control the frequency of cleaning.

Japanese Patent Laid-Open No. 7-60241 JP 2009-195818 A

  However, Patent Document 1 does not include a mechanism for detecting deterioration of the quality of seawater that is the water to be treated, and it becomes difficult to cope with the deterioration of the quality of the water to be treated.

  Moreover, in patent document 2, turbidity is measured as the quality of to-be-processed water. When seawater or brackish water is used as the water to be treated, it takes usually one day or more offline in order to measure sugar and protein, which are factors that cause biofouling in the water to be treated, as water quality. This makes it difficult to control online.

  Therefore, the present invention provides a desalination system that has good responsiveness to fluctuations in the quality of water to be treated and that can suppress biofouling generation and enable stable operation.

  In order to solve the above-described problems, the desalination system of the present invention includes a biological treatment apparatus in which treated water into which a flocculant has been injected flows and holds microorganisms that assimilate organic matter in the treated water, and the biological treatment A pretreatment unit comprising a filter for removing pollutants from the water to be treated flowing out from the apparatus, and the water to be treated flowing out from the filter are separated into permeated water from which salt has been removed and concentrated water from which salt has been concentrated. The pretreatment unit is controlled based only on a reverse osmosis membrane module, a pressure gauge that measures the pressure of the water to be treated flowing into the filter, and a pressure of the water to be treated that flows into the filter measured by the pressure gauge. It has the control apparatus which performs.

  ADVANTAGE OF THE INVENTION According to this invention, the responsiveness with respect to the water quality fluctuation | variation of to-be-processed water is good, The bio-fouling production | generation can be suppressed and the desalination system which enables the stable driving | operation can be provided.

  In this invention, the pressure of the to-be-processed water which flows out out of a biological treatment apparatus and flows in into a filter is measured, and a pre-processing part is controlled based only on the measured pressure. Therefore, for example, (1) filter clogging with biofilm (biofilm) peeled off from the biological treatment device, (2) increase in biofilm on the filter surface due to excess biodegradable components that could not be taken up by the biological treatment device The blockage can be detected immediately, and biofouling generation in the reverse osmosis membrane module can be suppressed by controlling the pretreatment unit.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is a whole block diagram of the desalination system which concerns on one Example of this invention. It is a flowchart which shows the control procedure of the coagulant | flocculant injection pump by the control apparatus shown in FIG. It is a figure which shows the removal performance of the biodegradable component contained in the to-be-processed water by the desalination system shown in FIG. It is a whole block diagram of the desalination system which concerns on the other Example of this invention. It is a flowchart which shows the control procedure of the coagulant | flocculant injection pump by the control apparatus shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an overall configuration diagram of the desalination system of the present invention. In FIG. 1, solid arrows indicate the flow of water, and dotted arrows indicate signal lines. A desalination system 100 according to the present invention includes a sand filtration device 11, a biological treatment device 14, a filter 16, a reverse osmosis membrane (RO membrane: Reverse Osmosis) in order from the intake of seawater or brackish water that is treated water (raw water). Membrane) module 18 is arranged, and the reverse osmosis membrane module 18 is configured to perform membrane separation of the water to be treated into permeated water (fresh water) 6 and concentrated water 7 which is high-concentration salt water.

  A water intake pipe 1 extending from seawater or brackish water that is to be treated is connected to a sand filtration device 11, and a water intake pump 10 is attached to the water intake pipe 1. A branch pipe 2 branched from the intake pipe 1 is connected to a flocculant tank 13, and a flocculant pump 12 is attached to the branch pipe 2. The flocculant pump 12 injects the flocculant from the flocculant tank 13 into the intake pipe 1. The flocculant tank 13 stores an inorganic flocculant or a polymer flocculant. For example, ferric chloride is used as the inorganic flocculant, and polyacrylamide flocculant is used as the polymer flocculant. Here, brackish water refers to water containing salt such as sodium chloride, brackish water that exists at the boundary with seawater is also included in brackish water, and fossil water and salt zone formed by seawater in the past. Irrigation also exists in land water such as salty water.

  The flocculant injected into the water to be treated via the branch pipe 2 captures impurities such as organic substances in the water to be treated and forms a flocculent floc. The water to be treated containing coagulated floc is supplied to the sand filtration device 11, and the water to be treated after being filtered is supplied to the biological treatment device 14 via the pipe 3. The biological treatment apparatus 14 has a biological layer holding microorganisms that assimilate organic matter contained in the water to be treated. The treated water flowing out from the biological treatment apparatus 14 is supplied to the filter 16 via the pipe 4. A first pressure gauge 15 is attached to the pipe 4 connecting the biological treatment apparatus 14 and the filter 16 so that the pressure of the water to be treated flowing into the filter 16 can be measured.

  The filter 16 and the reverse osmosis membrane module 18 are connected by a pipe 5, and a high-pressure pump 17 is attached to the pipe 5. The filter 16 is, for example, a safety filter, a microfiltration membrane (MF membrane: Microfiltration Membrane) or an ultrafiltration membrane (UF membrane: Ultrafiltration Membrane), and the filter pore size is a safety filter, microfiltration membrane, ultrafiltration. Smaller in order of membrane. The control device 8 is connected to the input device 9, the first pressure gauge 15, and the flocculant pump 12 by a signal line. In the desalination system 100 of the present invention, the sand filtration device 11, the biological treatment device 14, and the filter 16 constitute a pretreatment unit.

  Next, the operation of the desalination system 100 will be described. The intake pump 10 supplies the water to be treated to the sand filtration device 11 through the intake pipe 1. The water to be treated is injected with a flocculant by the flocculant pump 12 before flowing into the sand filtration device 11. By injecting the flocculant, contaminants (impurities) in the water to be treated are captured by the flocculant to form flocculent flocs, which are filtered by the sand filtration device 11 and removed from the water to be treated. The treated water flowing out from the sand filtration device 11 flows into the biological treatment device 14 through the pipe 3 and is biologically treated. That is, biodegradable components in the water to be treated are assimilated and reduced by the microorganisms held in the biological treatment apparatus 14. When a biodegradable component is assimilated by a microorganism, a biofilm is formed by a secretion fluid discharged from the microorganism. Here, the biodegradable component is a nutrient source for microorganisms among organic carbon dissolved in the water to be treated, and is generally organic carbon having a particle size of 1 nm or less. A part of the biofilm formed by the biological treatment apparatus 14 is peeled off, mixed into the treated water, and the treated water flowing out from the biological treatment apparatus 14 is reversed through the filter 16 by the operation of the high-pressure pump 17. Water is sent to the osmotic membrane module 18. At this time, the biofilm mixed in the water to be treated is captured by the filter 16, and the water to be treated that has flowed into the reverse osmosis membrane module 18 is concentrated in the permeated water (fresh water) 6 from which the salt content has been removed by the reverse osmosis treatment. The concentrated water 7 is separated.

  The control device 8 controls the operation of the desalination system 100 by controlling the flocculant pump 12 and the high-pressure pump 17, but hereinafter, the measured value by the first pressure gauge 15, that is, flows into the filter 16. An operation of controlling the injection amount of the flocculant by the flocculant pump 12 based on the filter pressure increase rate calculated from the measured pressure of the water to be treated (hereinafter, filter pressure) will be described. The filter pressure increase rate is an increase width of the filter pressure with respect to the water passing time.

FIG. 2 is a flowchart showing a control procedure of the flocculant injection pump according to one embodiment of the present invention. As shown in FIG. 2, the upper limit target value v Pf_h of the previously inputted from the input device 9 filter pressure increase rate, the lower limit target value v Pf_l, and reading from the storage device (not shown) the upper limit value r h of the coagulant injection rate, Time variation data of the measured value P f of the filter pressure during a certain period is acquired from the first pressure gauge 15 (step S11). The filter pressure increase rate v pf is calculated from the time variation data of the filter pressure measurement value P f (step S12).

Subsequently, the calculated value v pf of the filter pressure increase rate is compared with the upper limit target value v pf_h (step S13). If the filter pressure increase velocity v pf exceeds the upper limit target value v pf_h, it compares the coagulant injection rate r coagulant injection rate limit r h (step S14). When coagulant injection rate r is less coagulant injection rate limit r h, the coagulant injection rate r according coagulant pump 12 is increased by [Delta] r, the flow returns to step S11 (step S15). On the other hand, coagulant injection rate r may exceed the coagulant injection rate limit r h, etc. (not shown) display device, and outputs a signal indicating a warning that exceeds the coagulant injection rate limit.

In step S13, when the calculated value v pf the filter pressure increase rate is equal to or less than the upper limit target value v Pf_h filter pressure increase rate, it compares the calculated value v pf the filter pressure increase speed and lower target values v pf_l. (Step S16). When the filter pressure increase velocity v pf is less than the lower limit target value v Pf_l, it returns the coagulant injection rate r according coagulant pump 12 to the step S11 is decreased by [Delta] r (step S17). On the other hand, if the filter pressure increase velocity v pf is more than the lower limit target value v Pf_l, it returns to the step S11 without changing the coagulant injection rate.

By repeatedly executing these steps S11 to S17, it becomes possible to obtain a flocculant injection rate corresponding to the quality of the water to be treated. Incidentally, the increase Δr for the coagulant injection rate is kept may be suitably based on the difference between the current coagulant injection rate r and the upper limit value r h of the coagulant injection rate, necessarily advance optimum value of Δr calculated There is no need. This is because the flocculant injection rate according to the quality of the water to be treated is obtained in a self-aligning manner by repeatedly executing Steps S11 to S17 as described above.

  If the biodegradable component is contained in the water to be treated in a range that exceeds the processing capacity of the sand filtration device 11, the rate of increase in the filter pressure may not decrease even if the flocculant injection rate is increased. Alternatively, there is a possibility that the optimum injection region of the flocculant is off. According to the present embodiment, even in such a situation, as described above, a warning is output to the display device or the like. Therefore, the operator of the desalination system puts powdered activated carbon in the front stage of the sand filtration device 11 and stops the intake of water. Or, it is possible to take measures such as correction of the flocculant injection rate by a jar tester.

In this embodiment, the calculated value v pf the filter pressure increase rate exceeds the upper limit target value v Pf_h, and only outputs a warning when the coagulant injection rate r exceeds an upper limit value r h of the coagulant injection rate Although it was configured, it is not limited to this. For example, a warning may be output when the calculated value v pf of the filter pressure increase rate becomes equal to or lower than the lower limit target value v pf — l of the filter pressure increase rate. Further, a warning may be output when the calculated value v pf of the filter pressure increase rate exceeds the upper limit target value v pf_h .

The filter pressure increase rate of the upper limit target value v Pf_h, filter pressure increase rate of the lower limit target value v Pf_l and coagulant injection rate limit r h of previously jar using a tester or the like, application to equipment coagulant injection It is desirable to measure the response time of the water quality change with respect to the rate change, and to set based on the allowable range of the quality of water supplied to the reverse osmosis membrane module 18.

  FIG. 3 is a diagram showing the removal performance of biodegradable components contained in the water to be treated by the desalination system shown in FIG. In the biological treatment, when the biodegradable component flowing in increases, the formation of a biofilm increases and the removal performance of the biodegradable component improves, but this reaction takes time. For this reason, when the water quality of the conventional to-be-treated water is detected off-line, the period in which the target value of the quality of water supplied to the reverse osmosis membrane module is exceeded becomes longer. On the other hand, in a present Example, the response time of the water quality change with respect to a driving | running condition change is comparatively short, and the removal performance in the pre-processing part comprised by the sand filtration apparatus 11 and the biological treatment apparatus 14 is improved. As a result, it is possible to shorten the period of exceeding the target value of the quality of water supplied to the reverse osmosis membrane module as compared with the conventional method.

  In addition, in the present Example, although the case where the sand filtration apparatus 11 which introduces the to-be-processed water after flocculant injection | pouring was used as a pre-processing part was shown, it replaced with this and a sand filtration apparatus, UF membrane processing apparatus, A flotation separator may be used so that the flocculant is not injected during normal operation and the flocculant or powdered activated carbon is charged only when the water quality deteriorates.

  According to the present embodiment, by detecting the deterioration of the quality of the water to be treated and controlling the pretreatment unit, the deterioration of the quality of the water to be treated supplied to the reverse osmosis membrane module 18 is suppressed, and biofouling is generated. Can be avoided. Further, according to the present embodiment, only a pressure gauge for measuring the pressure of the water to be treated flowing into the filter 16 may be installed, eliminating the need for a water quality meter or off-line water quality analysis, and reducing the quality of the water to be treated. Deterioration can be detected.

  In this embodiment, the biological treatment apparatus 14 is provided with a disk-shaped rotating body for attaching microorganisms to form a biological film in the treated water tank, and a rotating disk system for assimilating organic matter in the water to be treated by the microorganisms. And a biological treatment apparatus of open air type such as a sprinkling filter type biological treatment apparatus in which a biological layer having microorganisms attached in a treatment tank and a treated water sprayed from above can be used. This is because, although the open-air biological treatment apparatus cannot detect the increase in filtration resistance due to the increase in the number of biofilms formed by pressure, in this embodiment, the water to be treated that flows into the filter disposed at the subsequent stage of the biological treatment apparatus Therefore, the present invention can also be applied to these open-air biological treatment apparatuses.

  A sealed biological treatment apparatus having a biological activated carbon tower that attaches microorganisms to the surface of the filled activated carbon, adsorbs the organic matter in the treated water to be passed to the activated carbon, and then assimilate the adsorbed organic matter by the microorganisms. Can also be used.

  In this way, the entire desalination system can be stably operated by controlling the pretreatment unit in response to the water quality fluctuation of the water to be treated. In addition, the occurrence of biofouling in the reverse permeable membrane module 18 can be suppressed, the frequency of membrane cleaning and replacement can be reduced, and the operating cost required for replacement of cleaning chemicals and membrane modules can be reduced.

  FIG. 4 shows an overall configuration diagram of a desalination system according to an embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. The present embodiment is different from the first embodiment in that the second pressure gauge 19 is attached to the pipe 3 that connects the sand filtration device 11 and the biological treatment device 14.

  A water intake pipe 1 extending from the water to be treated is connected to a sand filtration device 11, and a water intake pump 10 is attached to the water intake pipe 1. A branch pipe 2 branched from the intake pipe 1 is connected to a flocculant tank 13, and a flocculant pump 12 is attached to the branch pipe 2. The flocculant pump 12 injects the flocculant from the flocculant tank 13 into the water to be treated flowing through the intake pipe 1. A second pressure gauge 19 is attached to the pipe 3 connecting the sand filtration device 11 and the biological treatment device 14, and the pressure of water to be treated flowing into the biological treatment device 14 is measured for a predetermined period, and then to the control device 8. It is configured to output. Moreover, the 1st pressure gauge 15 is attached to the piping 4 which connects the biological treatment apparatus 14 and the filter 16, and the pressure of the to-be-processed water which flows into the filter 16 from the biological treatment apparatus 14 is measured for a predetermined period, and is controlled. It is configured to output to the device 8. The filter 16 and the reverse osmosis membrane module 18 are connected by the pipe 5, and the water to be treated after being filtered by the filter 16 is pressurized by the high pressure pump 17 attached to the pipe 5 and flows into the reverse osmosis membrane module 18 to remove the salt. The permeated water (fresh water) 6 and the concentrated water 7 in which the salt content is concentrated are separated. The operation of the desalination system 100 'is the same as that of the first embodiment, and the description thereof is omitted below.

  In this embodiment, the control device 8 increases the biological treatment pressure increase rate calculated from the measurement value by the second pressure gauge 19, that is, the measurement value of the pressure of water to be treated (hereinafter referred to as biological treatment pressure) flowing into the biological treatment device. And the injection amount of the flocculant by the flocculant pump 12 is controlled based on the measured value of the first pressure gauge 15, that is, the filter pressure increase rate calculated from the measured filter pressure value. The biological treatment pressure increase rate is the increase width of the biological treatment pressure with respect to the water passage time, and the filter pressure increase rate is the increase width of the filter pressure with respect to the water passage time.

FIG. 5 is a flowchart showing a control procedure of the coagulant injection pump in the present embodiment. As shown in FIG. 5, upper limit target values v pb_h, v pf_h, lower limit target values v pb_l, v pf_l , and flocculant injection for biological treatment pressure increase rate and filter pressure increase rate input in advance from the input device 9 The upper limit value r h of the rate is read from a storage device (not shown ), and the time fluctuations of the measured values P b and P f of the biological treatment pressure and the filter pressure during a certain period from the second pressure gauge 19 and the first pressure gauge 15 Data is acquired (step S21). From the time variation data of biological treatment pressure measurements P b and the filter pressure measuring value P f, respectively to calculate the biological treatment pressure increase velocity v pb and filter pressure increase rate v pf (step S22).

Subsequently, the calculated value v pb of the biological treatment pressure increase rate is compared with the upper limit target value v pb_h (step S23). If biological treatment pressure increase velocity v pb exceeds the upper limit target value v pb_h, it compares the coagulant injection rate r coagulant injection rate limit r h (step S24). When coagulant injection rate r is less coagulant injection rate limit r h, the coagulant injection rate r according coagulant pump 12 is increased by [Delta] r, the flow returns to step S21 (step S25). If agglutination injection rate r exceeds a coagulant injection rate limit r h, etc. (not shown) display device, and outputs a signal indicating a warning that exceeds the coagulant injection rate limit.

In step S23, when the biological treatment pressure increase rate v pb is equal to or lower than the upper limit target value v pb_h , the calculated value v pf of the filter pressure increase rate is compared with the upper limit target value v pf_h (step S26). When the calculated value v pf of the filter pressure increase rate exceeds the upper limit target value v pf — h of the filter pressure increase rate, the flocculant injection rate r is compared with the upper limit value r h of the flocculant injection rate (step S27). ). Coagulant injection rate r is the case of more than the upper limit r h of the coagulant injection rate, increase the coagulant injection rate r according coagulant pump 12 by [Delta] r, the flow returns to step S21 (step S28). On the other hand, when the coagulant injection rate r exceeds the upper limit value rh of the coagulant injection rate in step S27, a signal indicating a warning that the coagulant injection rate upper limit has been exceeded is output to a display device (not shown).

When the filter pressure increase rate v pf is equal to or lower than the upper limit target value v pf — h of the filter pressure increase rate in step S26, the calculated biological treatment pressure increase rate v pb is used as the lower limit target value v pb — of the biological process pressure increase rate. 1 (step S29). When the calculated value v pb of the biological treatment pressure increase rate is equal to or lower than the lower limit target value v pb — l of the biological pressure increase rate, the calculated value v pf of the filter pressure increase rate and the lower limit target value v pf of the filter pressure increase rate Compare _ l (step S30). As a result of the comparison, if the calculated value v pf of the filter pressure increase rate is equal to or lower than the lower limit target value v pf — l of the filter pressure increase rate, the coagulant injection rate r by the coagulant injection pump 12 is decreased by Δr and the process proceeds to step S21. Return (step S31). On the other hand, if the calculated value v pf of the filter pressure increase rate exceeds the lower limit target value v pf — l of the filter pressure increase rate, the process returns to step S21 without changing the flocculant injection rate r.

If the calculated value v pb of the biological treatment pressure increase rate exceeds the lower limit target value v pb — l of the biological pressure increase rate in step S29, the process returns to step S21 without changing the flocculant injection rate r.

By repeatedly executing these steps S21 to S31, it becomes possible to obtain a flocculant injection rate corresponding to the quality of the water to be treated. The increase Δr of coagulant injection rate may be appropriately set based on the difference between the current coagulant injection rate r and the upper limit value r h of the coagulant injection rate, always necessary to beforehand determine the optimum value of Δr There is no. This is because the flocculant injection rate according to the quality of the water to be treated is obtained in a self-aligning manner by repeatedly executing Step S21 to Step S31 as described above.

In this embodiment, (1) the calculated value v pb of the biological treatment pressure increase rate exceeds the upper limit target value v pb — h of the biological pressure increase rate, and the current flocculant injection rate r is the flocculant injection rate. When the upper limit value r h is exceeded, or (2) the calculated value v pf of the filter pressure increase rate exceeds the upper limit target value v pf — h of the filter pressure increase rate, and the current flocculant injection rate r is the flocculant If it exceeds the upper limit value r h infusion rate, and the like (not shown) display device, a configuration for outputting a signal indicating a warning that exceeds the coagulant injection rate limit, not limited thereto. For example, (1) when the calculated value v pb of the biological treatment pressure increase rate exceeds the upper limit target value v pb — h of the biological pressure increase rate, (2) the calculated value v pf of the filter pressure increase rate becomes the filter pressure increase rate. When the upper limit target value v pf — h is exceeded (3) When the calculated biological treatment pressure increase rate v pb is less than or equal to the lower limit target value v pb — l of the biological pressure increase rate, or (4) Filter When the calculated value v pf of the pressure increase rate is equal to or lower than the lower limit target value v pf — l of the filter pressure increase rate, a signal indicating a warning that the coagulant injection rate upper limit has been exceeded is output to a display device (not shown). It is good also as a structure.

Also, when the calculated value v pb biological treatment pressure increase rate exceeds the upper limit target value v pb _ h organisms pressure increase rate, because it advanced clogging of the biological treatment apparatus 14, by washing the biological treatment apparatus 14 Also good.

In addition, the upper limit target value v pb — h of the biological pressure increase rate, the lower limit target value v pb — l of the biological treatment pressure increase rate, the upper limit target value v pf — h of the filter pressure increase rate, and the lower limit target value of the filter pressure increase rate The v pf — l and the upper limit value r h of the flocculant injection rate are measured in advance using a jar tester or the like to measure the response time of the water quality change with respect to the change of the flocculant injection rate of the equipment to be applied. It is desirable to set based on the allowable range of the quality of the supplied water to 18.

  According to the present embodiment, by detecting the deterioration of the quality of the water to be treated and controlling the pretreatment unit, the deterioration of the quality of the water to be treated supplied to the reverse osmosis membrane module 18 is suppressed, and the fouling is generated. Can be avoided.

  Moreover, although the biological treatment apparatus 14 in this embodiment is limited to the above-described sealed biological treatment apparatus, according to this embodiment, the first pressure gauge that measures the pressure of the water to be treated flowing into the filter 16. And the pressure value measured by the second pressure gauge 19 that measures the pressure of the water to be treated flowing into the biological treatment apparatus, thereby detecting the water quality deterioration of the water to be treated with higher accuracy than in the first embodiment. it can. And like Example 1, a water quality meter and an off-line water quality analysis are unnecessary, and the deterioration of the quality of to-be-processed water can be detected at low cost.

  In this way, the entire desalination system can be stably operated by controlling the pretreatment unit in response to the water quality fluctuation of the water to be treated. In addition, the occurrence of biofouling in the reverse osmosis membrane module 18 can be suppressed, the frequency of membrane cleaning and replacement can be reduced, and the operating cost required for replacement of cleaning chemicals and membrane modules can be reduced.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

DESCRIPTION OF SYMBOLS 1 Intake pipe 2 Branch pipe 3, 4, 5 Pipe 6 Permeated water 7 Concentrated water 8 Control apparatus 9 Input apparatus 10 Intake pump 11 Sand filtration apparatus 12 Coagulant pump 13 Coagulant tank 14 Biological treatment apparatus 15 1st pressure gauge 16 Filter 17 High-pressure pump 18 Reverse osmosis membrane module 19 Second pressure gauge 100, 100 ′ Desalination system

Claims (12)

  1. From the biological treatment apparatus in which the treated water into which the flocculant has been injected flows and holding microorganisms that assimilate the organic matter in the treated water, and the filter that removes contaminants from the treated water flowing out of the biological treatment apparatus A pre-processing unit
    A reverse osmosis membrane module that separates water to be treated flowing out of the filter into permeated water from which salt content has been removed and concentrated water from which salt content has been concentrated;
    A pressure gauge for measuring the pressure of the water to be treated flowing into the filter;
    A desalination system comprising a control device for controlling the pretreatment unit based only on the pressure of the water to be treated flowing into the filter measured by the pressure gauge.
  2. The desalination system according to claim 1,
    The control device obtains the pressure increase rate of the water to be treated flowing into the filter from the measured pressure of the water to be treated, and controls the pretreatment unit so that the obtained pressure increase rate falls within a predetermined range. A desalination system characterized by
  3. The desalination system according to claim 2,
    The control device holds an upper limit value and a lower limit value of the pressure increase rate in advance, and outputs a signal indicating a warning when the pressure increase rate of the treated water exceeds the upper limit value. Desalination system.
  4. The desalination system according to claim 2,
    The said control apparatus controls the injection | pouring rate of the coagulant | flocculant inject | poured into the said to-be-processed water so that the calculated | required pressure increase rate may become a predetermined range, The desalination system characterized by the above-mentioned.
  5. The desalination system according to claim 4,
    The controller is
    Furthermore, the upper limit of the injection rate of the flocculant is held in advance,
    When the obtained pressure increase rate exceeds the upper limit value of the pressure increase rate and the injection rate of the flocculant is equal to or lower than the upper limit value of the injection rate, the injection rate of the flocculant injected into the water to be treated is increased. A desalination system characterized by control.
  6. From the biological treatment apparatus in which the treated water into which the flocculant has been injected flows and holding microorganisms that assimilate the organic matter in the treated water, and the filter that removes contaminants from the treated water flowing out of the biological treatment apparatus A pre-processing unit
    A reverse osmosis membrane module that separates water to be treated flowing out of the filter into permeated water from which salt content has been removed and concentrated water from which salt content has been concentrated;
    A first pressure gauge for measuring the pressure of the water to be treated flowing into the filter;
    A second pressure gauge for measuring the pressure of water to be treated flowing into the biological treatment apparatus;
    A desalination system comprising a control device for controlling the pretreatment unit based only on the pressure of the water to be treated measured by the first and second pressure gauges.
  7. The desalination system according to claim 6,
    The control device obtains a filter inlet pressure increase rate, which is a pressure increase rate of the water to be treated flowing into the filter, from the measurement value of the first pressure gauge, and the biological treatment from the measurement value of the second pressure gauge. The biological treatment apparatus inlet pressure increase speed, which is the pressure increase speed of the water to be treated flowing into the apparatus, is obtained, and the pretreatment unit is disposed so that the obtained filter inlet pressure increase speed and biological treatment apparatus inlet pressure increase speed are within a predetermined range. A desalination system characterized by control.
  8. The desalination system according to claim 7,
    The controller is
    An upper limit value and a lower limit value of the filter inlet pressure increase rate, and an upper limit value and a lower limit value of the biological treatment device inlet pressure increase rate are held in advance,
    A desalination system which outputs a signal indicating a warning when at least one of the obtained filter pressure increase rate and biological treatment apparatus inlet pressure increase rate exceeds the upper limit value.
  9. The desalination system according to claim 7,
    The control device controls the injection rate of the flocculant injected into the water to be treated so that the obtained filter inlet pressure increase rate and biological treatment device inlet pressure increase rate are within a predetermined range. System.
  10. The desalination system according to claim 8,
    The controller is
    Furthermore, an upper limit value of the injection rate of the flocculant is previously held,
    When the obtained biological treatment apparatus inlet pressure increase rate exceeds the upper limit and the flocculant injection rate is equal to or lower than the upper limit of the injection rate, or the obtained filter inlet pressure increase rate exceeds the upper limit And when the injection rate of the flocculant is below the upper limit of the injection rate, the desalination system is controlled to increase the injection rate of the flocculant injected into the water to be treated.
  11. From the biological treatment apparatus in which the treated water into which the flocculant has been injected flows and holding microorganisms that assimilate the organic matter in the treated water, and the filter that removes contaminants from the treated water flowing out of the biological treatment apparatus A pre-processing unit
    A reverse osmosis membrane module that separates water to be treated flowing out of the filter into permeated water from which salt content has been removed and concentrated water from which salt content has been concentrated;
    A desalination system comprising: a control device that controls at least an injection rate of a flocculant injected into the water to be treated based on a pressure increase rate of the water to be treated flowing into the filter.
  12. The desalination system according to claim 11,
    The control device determines at least an injection rate of the flocculant to be injected into the water to be treated based on the pressure increase rate of the water to be treated flowing into the filter and the pressure increase rate of the water to be treated flowing into the biological treatment device. A desalination system characterized by control.
JP2013188031A 2013-09-11 2013-09-11 Desalination system Pending JP2015054273A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006223921A (en) * 2005-02-15 2006-08-31 Toray Ind Inc Water treatment method
JP2008168199A (en) * 2007-01-11 2008-07-24 Hitachi Ltd Membrane separation activated sludge apparatus and its operation method
JP2009208012A (en) * 2008-03-05 2009-09-17 Japan Organo Co Ltd Water treating method and water treating apparatus
JP2011240342A (en) * 2006-04-21 2011-12-01 Maezawa Ind Inc Wastewater treatment apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006223921A (en) * 2005-02-15 2006-08-31 Toray Ind Inc Water treatment method
JP2011240342A (en) * 2006-04-21 2011-12-01 Maezawa Ind Inc Wastewater treatment apparatus
JP2008168199A (en) * 2007-01-11 2008-07-24 Hitachi Ltd Membrane separation activated sludge apparatus and its operation method
JP2009208012A (en) * 2008-03-05 2009-09-17 Japan Organo Co Ltd Water treating method and water treating apparatus

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