JP2008126223A - Membrane treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the load of a separation membrane by monitoring and removing humic substances dissolved in raw water. <P>SOLUTION: This membrane treatment system 1 is equipped with a flocculant injection device 13 for injecting a flocculant in the raw water supplied to a membrane treatment device 10. The flocculant injection device 13 injects the flocculant in the raw water on the basis of the concentration of humic substances of the raw water. This flocculant injection device 13 may inject the flocculant in the raw water on the basis of the concentration of humic substances of the water filtrate discharged from the membrane treatment device 10. The absorbance or chromaticity of ultraviolet rays is designated as the concentration index of humic substances. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water treatment technique using a membrane module for waterworks.

  Membrane treatment systems for waterworks using separation membranes made of organic or inorganic materials are used in many water purification plants. Since the original purpose of membrane treatment is to remove suspended substances in water (such as sand, silt, algae, fungi, protozoa, etc.), many water purification plants use a measuring device to detect suspended substances. Is being monitored.

  On the other hand, dissolved substances of natural water such as soluble manganese and humic substances may block the separation membrane depending on the physicochemical form. When the separation membrane is clogged, it is necessary to remove clogging-causing substances by washing, and the cost increases due to a decrease in water recovery rate and an increase in man-hours, which is not economical. In order to treat raw water containing a soluble substance with a membrane treatment system, it is common to remove the substance to be treated by a pretreatment process before the membrane treatment (for example, Patent Document 1 and Non-Patent Document 1).

Further, in the membrane treatment, it is necessary to perform washing in order to maintain the functionality of the membrane, and backflow washing several times a day and chemical washing several times a year are performed. In the backwashing, an oxidizing agent containing a low concentration of hypochlorite may be added (for example, Patent Document 2 and Patent Document 3). The cleaning cycle is managed by a timer, and the membrane processing system can be automatically operated even if there are frequent back-flow cleaning steps.
JP 06-031272 “Environmental Technology / Equipment Dictionary” Editorial Committee, “Environmental Technology / Equipment Dictionary I”, February 17, 2003, pp. 726 JP-A-10-296060 JP2003-251370

  Although humic substances are causative substances that block the separation membrane, generally humic substances in raw water are not directly monitored. Therefore, there is a possibility that the operation is not related to suppression of fouling of the separation membrane. Moreover, since the humic substance is not directly monitored in the cleaning waste water from the separation membrane, the cleaning effect cannot be confirmed.

  The membrane treatment system according to claim 1 includes a flocculant injecting device that injects a flocculant into the raw water supplied to the membrane processing device, and the flocculant injecting device converts the flocculant into the raw water based on the humic substance concentration of the raw water. inject.

  A membrane treatment system according to a second aspect is the membrane treatment system according to the first aspect, wherein the flocculant injecting device injects the flocculant into the raw water based on a humic substance concentration of filtered water discharged from the membrane processing device.

  A membrane treatment system according to a third aspect is the membrane treatment system according to the first or second aspect, further comprising a washing water supply device that supplies washing water to the membrane treatment device, and the washing water supply device is discharged from the membrane treatment device. The supply of the washing water is continued and stopped based on the humic substance concentration of the washing waste water.

  A membrane treatment system according to a fourth aspect of the present invention is the membrane treatment system according to the third aspect, further comprising a hyponitrous acid injection device for injecting hyponitrous acid into the cleaning water supplied to the membrane treatment device, The hyponitrous acid is injected into the cleaning water based on the residual chlorine concentration of the cleaning effluent discharged from the membrane treatment apparatus.

  The membrane treatment system according to claim 5 is the membrane treatment system according to claim 4, wherein the hyponitrous injecting device is a pressure of cleaning water supplied to the membrane processing device and a pressure of cleaning wastewater discharged from the membrane processing device. Hydrous acid is injected into the wash water based on the pressure difference between

  The film processing system according to claim 6 is the film processing system according to claim 1, wherein the index of the humin concentration is ultraviolet absorbance or chromaticity.

  According to the above-described invention, the humic substance serving as a load on the separation membrane is monitored and the raw water is supplied to the separation membrane in a state where the humic substance is removed, so that the life until the separation membrane is washed is extended.

  In particular, according to the inventions of claims 3 to 5, since the humic substances of the raw water clogged in the separation membrane are removed, the lack of cleaning of the separation membrane is solved. Moreover, since the concentration of humic substances in the cleaning waste water of the separation membrane is monitored, the cleaning effect of the separation membrane can be confirmed. Furthermore, according to the invention of claim 4 and claim 5, the injection quantity of hyponitrous acid used for cleaning the separation membrane is optimized.

  FIG. 1 is a schematic diagram of a film processing system 1 according to a first embodiment of the invention.

  The film processing system 1 includes a film processing apparatus 10. The membrane treatment apparatus 10 is an upward flow type membrane separation apparatus. Examples of the separation membrane of the membrane processing apparatus 10 include an MF membrane having a pore diameter of about 0.1 μm. A supply pipe 11 for supplying raw water is connected to the membrane treatment apparatus 10. The supply pipe 11 is connected with an injection pipe 14 for injecting the flocculant supplied from the flocculant injection device 13 into the raw water.

  In addition, a UV meter 15 is installed in the supply pipe 11 as a means for measuring ultraviolet absorbance, which is an indicator of the concentration of humic substances that are dissolved substances of raw water after the flocculant is injected. The UV meter 15 is disposed between the film processing apparatus 10 and the injection tube 14. The UV meter 15 supplies the measurement value of the ultraviolet absorbance to the control unit 16.

  The controller 16 controls the injection of the flocculant based on a preset value of the UV absorbance of the raw water set in advance and the measured value of the UV absorbance supplied. For example, when the measured value> the set value, the flow rate value of the flocculant is set to the previous flow rate value + α. That is, the control unit 16 transmits an instruction for the flow rate of the flocculant to increase the flocculant injection amount to the flocculant injection device 13 when the measured value is higher than the set value.

  For example, humic substances which are dissolved substances of raw water have a correlation with the measured value of the absorbance at the UV meter (measurement wavelength 253.7 nm) 15. Therefore, if the measured value of the ultraviolet absorbance of the raw water is controlled, the membrane processing apparatus 10 It is possible to control the dissolved substance flowing into the gas. For example, if PAC is used as the flocculant, 40 to 60% and 80% of the UV absorbance component can be removed. As described above, dissolved substances in raw water as exemplified by humic substances are removed by the flocculant. When raw water is supplied to the membrane treatment apparatus 10, it is discharged from the discharge pipe 12 as membrane filtered water. Since the raw water is supplied to the membrane treatment apparatus 1 in a state in which the dissolved substances that become a load on the separation membrane of the membrane treatment apparatus 1 are removed, the life of the separation membrane until chemical cleaning is extended. It should be noted that the index of the dissolved substance concentration is almost the same in terms of chromaticity instead of ultraviolet absorbance.

  FIG. 2 is a schematic diagram of a film processing system 2 according to the second embodiment of the invention.

  The membrane treatment system 2 measures the ultraviolet absorbance, which is an index of the dissolved substance concentration of the membrane filtrate discharged from the membrane treatment apparatus 10 of the membrane treatment system 1, with a UV meter 21. The UV meter 21 is installed in the discharge pipe 12 of the film processing apparatus 10. The UV meter 21 supplies the measured value of the ultraviolet absorbance to the control unit 16.

  The control unit 16 controls the injection of the flocculant based on a preset value of the ultraviolet absorbance of the membrane filtration water set in advance and the measured value of the supplied ultraviolet absorbance. For example, when the measured value> the set value, the flow rate value of the flocculant is set to the previous flow rate value + α. That is, the control unit 16 transmits an instruction for the flow rate of the flocculant to increase the flocculant injection amount to the flocculant injection device 13 when the measured value is higher than the set value.

  For example, humic substances that are dissolved substances in the membrane filtration water have a correlation with the measured value of the absorbance at the UV meter (measurement wavelength 253.7 nm) 21, so if the meter side value of the ultraviolet absorbance of the membrane filtrate is controlled, The dissolved substance flowing into the membrane processing apparatus 10 can be controlled. If the flocculating agent is PAC, for example, as in the membrane processing system 1, it is possible to remove 40 to 60% and 80% of the UV absorbance component. As described above, dissolved substances in raw water as exemplified by humic substances are removed by the flocculant.

  In the membrane treatment system 1, the measured value of the ultraviolet absorbance of the raw water supplied to the membrane treatment device 10 is controlled. However, if a UF membrane having a molecular weight cut off of about 10,000 is applied to the separation membrane of the membrane treatment device 10, the dissolved water is dissolved. Since substances are removed by the separation membrane, the amount of flocculant injected can be reduced by monitoring the concentration of dissolved substances in the membrane filtration water.

  When the raw water is supplied to the membrane treatment device 10, it is discharged from the discharge pipe 12 as membrane filtered water. Finally, the raw water is supplied to the membrane treatment apparatus 10 in a state in which the dissolved substance that becomes a load on the separation membrane of the membrane treatment apparatus 10 is removed, so that the life until the chemical separation of the separation membrane is extended. It should be noted that the index of the dissolved substance concentration is almost the same in terms of chromaticity instead of ultraviolet absorbance.

  FIG. 3 is a schematic diagram of a film processing system 3 according to the third embodiment of the invention.

  The membrane treatment apparatus 10 of the membrane treatment system 3 includes a washing water supply pipe 32 and a washing drain pipe 33. The cleaning water supply pipe 32 is supplied with cleaning water from the cleaning water supply device 31. From the cleaning drain pipe 33, the cleaning water used for cleaning the separation membrane of the cleaning water supply device 31 is discharged. For example, an MF membrane or a UF membrane is applied as the separation membrane of the membrane processing apparatus 10.

  Further, the cleaning drain pipe 33 is provided with a UV meter 34 as means for measuring the ultraviolet absorbance as an index of the concentration of humic substance which is a dissolved substance in the cleaning drain of the separation membrane. The UV meter 34 supplies the measurement value of the ultraviolet absorbance to the control unit 16.

  The control unit 16 determines the continuation and end of the cleaning based on the preset set value of the UV absorbance of the cleaning waste water and the measured value of the UV absorbance supplied. For example, cleaning is continued when the measured value> the set value. That is, the control unit 16 transmits an instruction to continue the cleaning to the cleaning water supply device 31 when the UV measurement value is higher than the set value. Then, an instruction to stop cleaning when the measured value ≦ the set value is satisfied is transmitted to the cleaning water supply device 31.

  For example, humic substances, which are dissolved substances in washing wastewater, have a correlation with the measured value of the absorbance at the UV meter (measurement wavelength 253.7 nm) 34. Therefore, if the measured value of the ultraviolet absorbance of the washing wastewater is controlled, membrane treatment The dissolved material that can be pushed out of the separation membrane of the device 10 can be controlled.

  And finally, since the dissolved substance clogged by the separation membrane is removed, insufficient cleaning of the separation membrane can be solved. It should be noted that the index of the dissolved substance concentration is almost the same in terms of chromaticity instead of ultraviolet absorbance.

  FIG. 4 is a schematic diagram of a film processing system 4 according to the fourth embodiment of the invention.

  The membrane treatment system 4 injects hyponitrous water into the wash water supplied to the membrane treatment device 10 based on the residual chlorine concentration in the washing wastewater of the membrane treatment device 10. Since there is a possibility that the amount of cleaning water increases in the membrane treatment system 3, the membrane treatment system 4 injects hyponitrous water into the washing water. The residual chlorine concentration in the cleaning waste water of the membrane treatment apparatus 10 is used as a factor for controlling the injection of hyponitrous acid.

  In the membrane treatment system 4, a hyponitrous water supply pipe 42 that injects hyponitrous acid supplied from the hyponitrous acid injection device 41 into the cleaning water is connected to the cleaning water supply pipe 32. Examples of the hypochlorous water include hypochlorous acid water and sodium hypochlorite aqueous solution. On the other hand, the cleaning drain pipe 33 is provided with a residual chlorine meter 43 for measuring the residual chlorine concentration of the cleaning drainage of the separation membrane. The residual chlorine meter 43 supplies the measured value of the residual chlorine concentration to the control unit 44. The control unit 44 controls the injection of the hyponitrous acid based on the measured value of the supplied residual chlorine concentration and the preset value of the residual chlorine concentration. For example, when the residual chlorine concentration measurement value> residual chlorine concentration set value, the flow rate value of hypochlorous water is set to the previous flow rate value + α. In other words, the control unit 16 transmits an instruction for the flow rate of hyponitrous water to increase the injection amount of the hypochlorous water when the measured value of residual chlorine concentration is higher than the set value of residual chlorine concentration, to the hypochlorous water injection device 41. To do.

  Also in the membrane treatment system 4, the control unit 16 controls the injection of the flocculant based on a preset value of the ultraviolet absorbance of the membrane filtrate and the measured value of the supplied ultraviolet absorbance. For example, cleaning is continued when the measured value> the set value. Then, an instruction to stop cleaning when the measured value ≦ the set value is satisfied is transmitted to the cleaning water supply device 31.

  For example, humic substances, which are dissolved substances in washing wastewater, have a correlation with the measured value of the absorbance at the UV meter (measurement wavelength 253.7 nm) 34. Therefore, if the measured value of the ultraviolet absorbance of the washing wastewater is controlled, membrane treatment The dissolved material that can be pushed out of the separation membrane of the device 10 can be controlled. In addition, since the degree of soiling of the separation membrane also changes due to the load of humic substances from the raw water, the amount of hyponitrogen injected into the wash water can be optimized by controlling the amount of hyponitrous injected.

  As described above, according to the membrane processing system 4, the dissolved substance clogged by the separation membrane is finally removed, and the lack of cleaning of the separation membrane is solved. It should be noted that the index of the dissolved substance concentration is almost the same in terms of chromaticity instead of ultraviolet absorbance.

  FIG. 5 is a schematic diagram of a film processing system 5 according to the fifth embodiment of the invention.

  In the membrane treatment system 5, a pressure gauge 51 for measuring the pressure of the washing waste water is provided in the washing drain pipe 33 of the membrane treatment system 4, and a pressure gauge 52 for measuring the pressure of the washing water is provided in the washing water supply pipe 32. The pressure values measured by the pressure gauges 51 and 52 are supplied to the control unit 44.

  The controller 44 controls injection of hyponitrous acid based on the supplied pressure value and a preset value of the membrane differential pressure of the membrane treatment apparatus 10. That is, the membrane differential pressure, which is the difference between the pressure value supplied from the pressure gauge 51 and the pressure value supplied from the pressure gauge 52, is a factor for determining the cleaning effect. The controller 44 determines an increase or a decrease in the injection amount of hyposulfite based on the measured membrane differential pressure and a preset membrane differential pressure. For example, when the measured membrane differential pressure value is greater than the set value of the membrane differential pressure, the flow rate value of hyponitrous water is set to the previous flow rate value + α. In this way, the control unit 44 instructs the flow rate of the hyponitrous water so as to increase the injection amount of the hyponitrous water when the measured value of the transmembrane pressure is higher than the set value of the transmembrane pressure. Send to. However, since the membrane differential pressure may not decrease due to aging contamination, the addition of hyponitrous acid may be stopped by a timer.

  In the membrane treatment system 5, the control unit 16 also controls the injection of the flocculant based on the preset value of the UV absorbance of the membrane filtrate and the measured value of the supplied UV absorbance. For example, cleaning is continued when the measured value> the set value. Then, an instruction to stop cleaning when the measured value ≦ the set value is satisfied is transmitted to the cleaning water supply device 31.

  For example, humic substances that are dissolved substances in the cleaning wastewater have a correlation with the measured value of the absorbance at the UV meter (measurement wavelength 253.7 nm) 34. Therefore, if the measured value of the ultraviolet absorbance of the cleaning wastewater is controlled, the membrane treatment apparatus The dissolved substances that can be extruded from 10 separation membranes can be controlled. In addition, since the degree of soiling of the separation membrane also changes due to the load of humic substances from the raw water, the amount of hyponitrogen injected into the wash water can be optimized by controlling the amount of hyponitrous injected. The indicator of the concentration of the dissolved substance gives almost the same result when the chromaticity is used instead of the ultraviolet absorbance.

  As described above, according to the membrane treatment system 5, the dissolved substance clogged by the separation membrane is finally removed, and the lack of cleaning of the separation membrane is solved. It should be noted that the index of the dissolved substance concentration is almost the same in terms of chromaticity instead of ultraviolet absorbance.

1 is a schematic diagram of a film processing system according to a first embodiment of the invention. The schematic diagram of the film processing system concerning a second embodiment of the invention. The schematic diagram of the film processing system concerning a third embodiment of the invention. The schematic diagram of the film processing system concerning a fourth embodiment of the invention. The schematic diagram of the film | membrane processing system which concerns on 5th embodiment of invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2, 3, 4, 5 ... Membrane processing system 10 ... Membrane processing apparatus, 11 ... Supply pipe, 12 ... Discharge pipe 13 ... Flocculant injection apparatus, 14 ... Injection tank 15, 16, 21, 34 ... UV meter 16 , 44 ... Control unit 31 ... Washing water supply device, 32 ... Washing water supply pipe, 33 ... Washing drain pipe 41 ... Hypochlorite injection device, 42 ... Hypochlorite supply pipe, 43 ... Residual chlorine meter 51, 52 ... Pressure Total

Claims (6)

A flocculant injecting device for injecting the flocculant into the raw water supplied to the membrane treatment device is provided,
The flocculant injection device injects the flocculant into the raw water based on the humic substance concentration of the raw water. The membrane treatment system according to claim 1, wherein the flocculant injecting device injects the flocculant into the raw water based on a humic concentration of filtrate water discharged from the membrane treatment device. A cleaning water supply device for supplying cleaning water to the membrane treatment device is provided.
3. The membrane treatment system according to claim 1, wherein the washing water supply device continues and stops the supply of the washing water based on a humic substance concentration of washing wastewater discharged from the membrane treatment device. . A hyponitrous injection device for injecting hyponitrous water into the wash water supplied to the membrane treatment device;
4. The membrane treatment system according to claim 3, wherein the hyponitrous acid injecting device injects the hyponitrous acid into the washing water based on a residual chlorine concentration of washing wastewater discharged from the membrane treating device. 5. The hyponitrous acid injection device injects hyponitrous acid into the cleaning water based on a differential pressure between the pressure of the cleaning water supplied to the membrane processing device and the pressure of the cleaning wastewater discharged from the membrane processing device. The film processing system according to claim 4.   The film processing system according to claim 1, wherein the humin concentration index is ultraviolet absorbance or chromaticity.

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