JP2011177689A - Water treatment system and treatment liquid discharge method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment system which can control a treatment liquid to a predetermined cleaning liquid content or less in case of manufacturing the treatment liquid with a separation membrane module after a cleaning of the separation membrane module in the water treatment system which filters a liquid to be treated by the separation membrane module, and a method of discharging the treatment liquid. <P>SOLUTION: The water treatment system 1 comprises a flow control tank 10 and a membrane separation tank 20 in which the separation membrane module 21 is arranged, and filters industrial waste water L1 flowing into the membrane separation tank 20 by the separation membrane module 21 to discharge. A controller 40 of a cleaning liquid content is provided and controls the cleaning liquid content of treated water L2 to a set value or less when after the separation membrane module 21 is cleaned, the treated water L2 manufactured by filtering the industrial waste water L1 by the separation membrane module 21 is discharged. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention adjusts the cleaning liquid content of the processing liquid when the processing liquid is manufactured by filtering the liquid to be processed through the separation membrane module after the separation membrane module provided in the membrane separation tank is cleaned with the cleaning liquid. The present invention relates to a treatment liquid discharge method and a water treatment system.

As is well known, when filtering a liquid to be treated such as factory wastewater, a membrane separation is performed in which aerobic microorganisms are suspended and retained in the liquid to be treated flowing into the membrane separation tank, and aeration is performed to produce the treatment liquid. The activated sludge method (MBR) is widely used.
In the membrane separation activated sludge method, when separating activated sludge from the liquid to be treated, for example, a separation membrane module using a separation membrane such as an ultrafiltration membrane made of PVDF (polyvinylidene fluoride), a microfiltration membrane, etc. Is used.

However, when a separation membrane module is used in the membrane separation activated sludge method, as the water to be treated is filtered, the separation membrane is gradually blocked and the separation performance is lowered.
Therefore, in order to recover the separation performance of the separation membrane module, a technology that efficiently eliminates the clogging of the separation membrane by circulating the cleaning liquid from the secondary side to the primary side while the separation membrane module is immersed in the membrane separation tank. Is disclosed (for example, see Patent Document 1).

  Such separation membrane module cleaning is performed periodically (for example, once a week) or depending on the state of the membrane pressure difference of the separation membrane module, for example, as a cleaning solution, a sodium hypochlorite aqueous solution (concentration 300 to 500 mg / L). ) Is used.

Japanese Patent Laid-Open No. 2000-300969

When the above separation membrane module is washed, high concentration of chlorine may remain on the treated water side for a certain period, but the emission standards stipulated in the Water Pollution Control Law do not provide for the chlorine concentration. No special management is required.
However, if treated water with a high residual chlorine concentration is discharged into rivers, lakes, and sea areas, it may affect the environment, and although temporarily, by discharging the treated water with a high residual chlorine concentration, There is also a possibility of adversely affecting the subsequent processing apparatus.

  The present invention has been made in consideration of such circumstances, and in a water treatment system that filters a liquid to be treated with a separation membrane module, after the separation membrane module is washed, a treatment liquid is produced with the separation membrane module. Another object of the present invention is to provide a water treatment system and a treatment liquid discharge method capable of adjusting the treatment liquid to a predetermined cleaning liquid content or less.

In order to solve the above problems, the present invention proposes the following means.
The invention according to claim 1 includes a flow rate adjusting tank and a membrane separation tank connected downstream of the flow rate adjusting tank and having a separation membrane module disposed therein, and the liquid to be treated that has flowed into the membrane separation tank is separated. A water treatment system for filtering and discharging by a membrane module, wherein a cleaning liquid is circulated from a secondary side to a primary side of the separation membrane module to wash the separation membrane module, and then the liquid to be treated is removed from the separation membrane module. In the case of discharging the processing liquid produced by filtration, the cleaning liquid content adjusting means for adjusting the cleaning liquid content of the processing liquid to a set value or less is provided.

  The invention according to claim 4 includes a flow rate adjusting tank and a membrane separation tank connected downstream of the flow rate adjusting tank and having a separation membrane module disposed therein, and the liquid to be treated that has flowed into the membrane separation tank is separated. In a water treatment system that filters and discharges through a membrane module, the cleaning liquid is circulated from the secondary side to the primary side of the separation membrane module to wash the separation membrane module, and then the liquid to be treated is filtered through the separation membrane module. The process liquid discharge method for discharging the process liquid manufactured in this way from the water treatment system is characterized in that the process liquid is discharged after the cleaning liquid content of the process liquid is adjusted below a set value.

  According to the water treatment system and the treatment liquid discharge method according to the present invention, after the separation membrane module is washed by flowing the cleaning liquid from the secondary side to the primary side of the separation membrane module, the treatment is filtered and manufactured by the separation membrane module. Adjust the cleaning solution content of the solution below the set value. As a result, even after the separation membrane module is washed, the washing liquid content of the treatment liquid discharged from the water treatment system can be suppressed to a set value or less.

In this specification, adjusting the cleaning liquid content of the processing liquid to a set value or less does not mean simply reducing the absolute value of the property to be managed with respect to the cleaning liquid content, but is within the range of the management standard ( Or, when the management characteristic is the residual chlorine concentration, it means approaching a set target value (1 mg / L, etc.).
In addition, the set value is not limited to the reference value specified in the Water Pollution Control Law, etc., even if the target is a substance specified in the Water Pollution Control Law, etc. Needless to say, any numerical value may be used as the set value.

  Invention of Claim 2 is the water treatment system of Claim 1, Comprising: The said washing | cleaning-liquid content adjustment means is a washing | cleaning-liquid content measuring means which measures the washing | cleaning-liquid content of a treatment liquid, and a treatment-liquid return means And when the measured value by the cleaning liquid content measuring means exceeds a set value, the processing liquid is returned to at least one of the flow rate adjusting tank and the membrane separation tank by the processing liquid returning means. It is characterized by being.

  Invention of Claim 5 is the processing liquid discharge | emission method of Claim 4, Comprising: The cleaning liquid content of a processing liquid is measured, and when the cleaning liquid content of a processing liquid exceeds a preset value, processing liquid is It is returned to at least one of the flow rate adjustment tank and the membrane separation tank, and the treatment liquid is discharged after setting the content of the cleaning liquid to a set value or less.

According to the water treatment system and the treatment liquid discharge method according to the present invention, the cleaning liquid content of the treatment liquid is measured, and when the measured value by the cleaning liquid content measuring means exceeds the set value, the treatment liquid is set as a flow rate adjustment tank. Since it is configured so as to be returned to at least one of the membrane separation tanks, processing (for example, neutralization, oxidation, reduction, etc.) is performed so that the cleaning liquid content of the processing liquid having a large cleaning liquid content approaches the set value. It is possible.
As a result, the cleaning content of the treatment liquid discharged from the water treatment system can be efficiently reduced below the set value.

  Invention of Claim 3 is the water treatment system of Claim 1, Comprising: The said washing | cleaning liquid content adjustment means is a washing | cleaning liquid content calculation means which calculates the washing | cleaning liquid content of a processing liquid, and a regulator addition means And based on the cleaning liquid content calculated by the cleaning liquid content calculating means, the adjusting agent adding means adds an amount of adjusting agent that makes the cleaning liquid content equal to or less than a set value to the processing liquid. It is characterized by being.

  Invention of Claim 6 is the processing liquid discharge | emission method of Claim 4, Comprising: The cleaning liquid content of a processing liquid is calculated, The said cleaning liquid content is set value based on the calculated said cleaning liquid content It is characterized in that the following amount of the adjusting agent is added, and the treatment liquid is discharged after the cleaning liquid content is set to a set value or less.

  According to the water treatment system and the treatment liquid discharge method according to the present invention, the cleaning liquid content of the treatment liquid is calculated, and based on the calculated cleaning liquid content, an adjustment agent is added in an amount that makes the cleaning liquid content equal to or less than a set value. Since it is comprised so that cleaning liquid content can be reduced.

  According to the water treatment system and the treatment liquid discharge method according to the present invention, when the treatment liquid is manufactured with the separation membrane module after the separation membrane module is washed, the treatment liquid can be adjusted to a predetermined washing liquid content or less. it can.

It is a figure showing the outline of the water treatment system concerning a 1st embodiment of the present invention. It is a flowchart explaining an example of cleaning liquid content adjustment in the water treatment system which concerns on 1st Embodiment. It is a figure which shows the outline of the water treatment system which concerns on the 2nd Embodiment of this invention. It is a flowchart explaining an example of cleaning liquid content adjustment in the water treatment system which concerns on 2nd Embodiment.

The first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram showing a first embodiment of a water treatment system according to the present invention, and reference numeral 1 denotes a water treatment system.

  The water treatment system 1 includes, for example, a flow rate adjusting tank 10, a membrane separation tank 20, a treated water tank 30, and a cleaning liquid content adjusting means 40, and factory waste water (treated liquid) L 1 that flows into the water treatment system 1. Is filtered by a membrane separation activated sludge method (MBR) to produce treated water (treated liquid) L2, which is discharged out of the water treatment system 1.

  The downstream side of the flow rate adjusting tank 10 is connected to the membrane separation tank 20 via the pipe 15, and temporarily stores the factory wastewater L1 flowing from the upstream side of the water treatment system 1. The stored factory wastewater L1 is transferred to the membrane separation tank 20 at a predetermined flow rate by the liquid feed pump 16 provided in the pipe 15.

  The membrane separation tank 20 includes, for example, a separation membrane module 21 provided with an ultrafiltration membrane, and aerobic microorganisms are suspended and retained in the factory wastewater L1 flowing in from the flow rate adjustment tank 10, and the factory wastewater L1 is aerated by aeration. Treated, passed from the primary side of the ultrafiltration membrane to the secondary side and filtered to remove the activated sludge and produce the treated water L2.

Further, the downstream side of the membrane separation tank 20 is connected to the treated water tank 30 via the pipe 25, and the treated water L <b> 2 is transferred from the membrane separation tank 20 to the treated water tank 30 by the filtration pump 26 provided in the pipe 25. It is like that.
The separation membrane module 21 is made of, for example, PVDF (polyvinylidene fluoride) as a material, and is installed so as to be immersed in the factory wastewater L1 stored in the membrane separation tank 20.

  The treated water tank 30 stores treated water L2 flowing from the membrane separation tank 20 via the pipe 25, and the treated water L2 overflows and is discharged out of the water treatment system 1 via the pipe 35, for example. It is like that.

  The cleaning liquid content adjusting means 40 includes, for example, a residual chlorine concentration measuring device (cleaning liquid content measuring means) 41 and a processing liquid returning means 42, and the chlorine content of the treated water L2 by the residual chlorine concentration measuring device 41 is When the set value is exceeded, the treated water L2 is returned to the flow rate adjusting tank 10 by the treated liquid returning means 42.

  The residual chlorine concentration measuring device 41 is arranged in the pipe 35, and intermittently measures the chlorine content of the treated water L2 discharged from the pipe 35 based on an instruction from the control unit 43. In addition, it may replace with intermittent measurement and may measure continuously.

The treatment liquid return means 42 includes a control unit 43, a treated water return pipe 44, a return pump 45, a motor valve 46, a signal cable 47, and a signal cable 48.
The control unit 43 is connected to the residual chlorine concentration measuring device 41 via the signal cable 47, acquires the chlorine content measured by the residual chlorine concentration measuring device 41 via the signal cable 47, and determines the chlorine content and the set value. When the chlorine content exceeds the set value, it is determined that there is an abnormality, and the treated water return signal is output to the return pump 45 and the motor valve 46 via the signal cable 48. .

The treated water return pipe 44 connects the treated water tank 30 and the flow rate adjusting tank 10, and the treated water return pipe 44 is provided with a return pump 45 and a motor valve 46 in this order from the treated water tank 30.
Further, between the return pump 45 of the treated water return pipe 44 and the motor valve 46, one end (upstream in the washing liquid flow direction) of the washing liquid pipe 36 connecting the treated water tank 30 and the secondary side of the separation membrane module 21 is connected. The other end (downstream of the cleaning liquid flow direction) of the cleaning liquid pipe 36 is connected between the separation membrane module 21 of the pipe 25 and the filtration pump 26. The cleaning liquid pipe 36 is provided with a motor valve 37 so as to control the flow of the cleaning liquid in the cleaning liquid pipe 36.

  The separation membrane module 21 is washed from the treated water tank 30 by opening the motor valve 37 and closing the motor valve 46 and stopping the filtration pump 26 and driving the return pump 45 by a control means (not shown). This is done by pumping the cleaning liquid to the secondary side of the module 21. The cleaning liquid is manufactured by, for example, dissolving sodium hypochlorite in the treated water L2 in the treated water tank 30.

The cleaning of the separation membrane module 21 is performed periodically, due to a difference in the membrane pressure of the separation membrane module 21, or when the water quality of the treated water L2 deteriorates.
Further, instead of pumping the cleaning liquid from the treatment water tank 30, the separation membrane module 21 may be cleaned using another known cleaning means (not shown).

Hereinafter, referring to FIG. 2, in the water treatment system 1, the separation membrane module 21 is washed with a washing liquid, and then the factory wastewater L1 is treated with activated sludge and then treated water L2 filtered by the separation membrane module 21 is manufactured. An example of a procedure for automatically adjusting the cleaning liquid content of the treated water L2 will be described.
(1) The chlorine content of the treated water L2 is measured by the residual chlorine concentration measuring device 41. (S1)
(2) It is determined whether the chlorine content is abnormal (S2).
If the chlorine content is abnormal, the process proceeds to S3, and if the chlorine content is normal, the process proceeds to S5.
(3) The return pump 45 is activated to open the motor valve 46 (S3).
(4) The treated water L2 is returned from the treated water tank 30 to the flow rate adjusting tank 10 (S4).
(5) If the chlorine content is normal, the treated water L2 is sent (drained) out of the water treatment system 1 (S5).
The above steps (2) to (5) are repeated.

  As described above, the control unit 43 outputs a treated water return signal, the return pump 45 is driven, and the motor valve 46 is opened, whereby the treated water L2 is returned to the flow rate adjustment tank 10. At this time, the motor valve 37 is closed.

  The residual chlorine in the treated water L2 returned to the flow adjustment tank 10 is reduced by the organic components of the factory wastewater (liquid to be treated) L1 flowing into the flow adjustment tank 10, and the residual chlorine content in the returned treated water L2 is descend. Then, the treated water L2 is transferred to the membrane separation tank 20, and the residual chlorine is reduced by aeration and treatment in an environment where aerobic microorganisms exist, and the residual chlorine content of the returned treated water L2 is reduced. It further falls and is transferred to the treated water tank 30 again.

  As a result, according to the water treatment system 1, the chlorine content of the treated water L2 discharged out of the system from the water treatment system 1 can be efficiently adjusted to a set value or less.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Drawing 3 is a figure showing water treatment system 2 concerning a 2nd embodiment.
The water treatment system 2 is different from the water treatment system 1 in that the water treatment system 2 includes a regulator addition means 50 instead of the cleaning liquid content adjustment means 40, and the other points are the water treatment system. 1 are the same as those in FIG.
In FIG. 3, the cleaning liquid pipe 36 and the motor valve 37 are not shown in the water treatment system 2.

The adjusting agent adding means 50 includes a residual chlorine concentration measuring device 51, a control unit 53 (cleaning liquid content calculating means), an adjusting agent adding device (adjusting agent adding means) 54, an adjusting agent tank 54T, and a signal cable 55. The signal cable 56 is provided.
In this embodiment, the measurement value of the residual chlorine concentration measuring device 51 is not used for calculating the adjustment agent addition amount, but only for determining whether or not the chlorine content exceeds the set value. It has become.

The control unit 53 acquires the measured value of the chlorine content of the residual chlorine concentration measuring device 51 via the signal cable 55, compares the measured value of the chlorine content with the set value, and the chlorine content is set to the set value. When it exceeds, it judges that it is abnormal and calculates the additive addition amount.
For example, referring to a database (not shown), the control unit 53 calculates the amount of the adjustment agent added, the type and concentration of the cleaning liquid used for cleaning the separation membrane module 21, the amount of treated water manufactured after cleaning, and the elapsed time after cleaning. Based on the above, it is calculated (predicted).
When the control unit 53 calculates the adjustment agent addition amount, the control unit 53 outputs a adjustment agent addition signal to the adjustment agent addition device 54 via the signal cable 56.

The adjusting agent adding device 54 collects a predetermined amount of adjusting agent from the adjusting agent tank 54T based on the adjusting agent addition signal, and adds the adjusting agent to the treatment water tank 30 (chemical injection control).
In this embodiment, for example, sodium bisulfite is used as the adjusting agent.

Hereinafter, referring to FIG. 4, in the water treatment system 2, the separation membrane module 21 is washed with the washing liquid, and then the factory wastewater L <b> 1 is treated with activated sludge and then treated water L <b> 2 filtered by the separation membrane module 21 is manufactured. An example of a procedure for automatically adjusting the cleaning liquid content of the treated water L2 will be described.
(1) The cleaning liquid content of the treated water L2 is measured by the residual chlorine concentration measuring device 51. (S11)
(2) The cleaning liquid content is compared with a set value to determine whether or not the cleaning liquid content is abnormal (S12).
If the cleaning liquid content is abnormal, the process proceeds to S13, and if the cleaning liquid content is normal, the process proceeds to S15.
(3) In the control unit 53, the amount of adjusting agent added is calculated (S13).
(4) The control unit 53 outputs a regulator addition signal to the regulator addition device 54 via the signal cable 56. Based on the adjustment agent addition signal from the control unit 53, the adjustment agent addition device 54 collects the instructed amount of the adjustment agent from the adjustment agent tank 54T and adds it to the treated water tank 30 (S14).
(5) If the cleaning liquid content is normal, the treated water L2 is sent out (drained) out of the water treatment system 2 (S15).
The above steps (2) to (5) are repeated.

  According to the water treatment system 2, since the addition amount of the regulator is predicted, calculated, and added, the cleaning liquid content can be efficiently reduced below the set value.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.
For example, in the above-described embodiment, the case where the treated water L2 is returned to the flow rate adjustment tank 10 in the water treatment system 1 has been described. For example, instead of the flow rate adjustment tank 10, the treated water L2 is added to the membrane separation tank 20. Or the treated water L2 may be returned to both the flow rate adjusting tank 10 and the membrane separation tank 20. Moreover, when returning to both the flow control tank 10 and the membrane separation tank 20, you may calculate and return the return ratio to each tank by arbitrary logics based on processing efficiency etc.
One or more aeration tanks may be provided between the flow rate adjustment tank 10 and the membrane separation tank 20, and the treated water L2 may be returned to these aeration tanks.

  In the said embodiment, although the separation membrane module 21 demonstrated the case where the separation membrane which consists of an ultrafiltration membrane was used, it replaced with an ultrafiltration membrane, and may use a microfiltration membrane etc., and material and shape For example, polyacrylonitrile, cellulose acetate, polysulfone, polyethylene, polypropylene, ceramics, polyethersulfone, polytetrafluoroethylene, and the like may be used instead of PVDF.

  Moreover, in the said embodiment, although the case where the treated water L2 which melt | dissolved sodium hypochlorite was used as a washing | cleaning liquid was demonstrated, according to the material of the separation membrane module to wash | clean, the purpose of filtration, a blockage state, etc., arbitrary In place of sodium hypochlorite, for example, an alkaline substance such as sodium hydroxide, an acidic substance such as hydrochloric acid, sulfuric acid, oxalic acid or citric acid, an aqueous solution of a surfactant, an alcohol or the like is used. May be.

Further, when measuring the cleaning liquid content of the treated water L2, other than the residual chlorine concentration may be used as a substitute characteristic.
Moreover, in the said embodiment, although the to-be-processed liquid demonstrated the case where it was factory wastewater L1, you may target other to-be-processed liquids, such as an alkaline liquid, an acidic liquid, and a solvent.

  Moreover, in the said embodiment, although the water treatment system 1 was provided with the control part 43 and the water treatment system 2 was provided with the control part 53, it did not depend on this control part 43 and 53, but to-be-processed manually. You may reduce the washing | cleaning liquid content of a liquid.

  Moreover, in the said embodiment, although the adjustment agent added to the treated water L2 demonstrated the case where it was sodium bisulfite for reducing sodium hypochlorite, other suitable according to the kind etc. of cleaning agent. Other drugs may be used.

  Further, in the water treatment system 2, the case where the residual chlorine concentration measuring device 51 is used only for detecting an abnormality has been described. However, even if the adjustment agent addition amount is calculated based on the measurement value of the residual chlorine concentration measuring device 51. Needless to say, it is good.

Further, for example, based on a database or the like, based on the type and concentration of the cleaning liquid used for cleaning the separation membrane module 21, the amount of processed water manufactured after cleaning, the elapsed time after cleaning, etc. If it is possible to reliably detect the cleaning liquid content measuring means such as the residual chlorine concentration measuring device 51, the cleaning liquid content measuring means may not be provided.
Moreover, it cannot be overemphasized that either processing procedure may be added to the processing procedure in the water treatment systems 1 and 2 shown to the flowchart of FIG. 2, FIG.

  In a water treatment system using a separation membrane module, when the treatment liquid is manufactured after washing the separation membrane module, the treatment liquid can be adjusted to a predetermined washing liquid content or less, so that it can be used industrially. is there.

L1 Factory wastewater (treated liquid)
L2 treated water (treatment liquid)
DESCRIPTION OF SYMBOLS 1, 2 Water treatment system 10 Flow control tank 20 Membrane separation tank 21 Separation membrane module 30 Treated water tank 40, 50 Cleaning liquid content adjustment means 41 Residual chlorine concentration measuring device (cleaning liquid content measurement means)
42 treatment liquid return means 53 control unit (cleaning liquid content calculation means)
54 Adjusting agent adding device (adjusting agent adding means)

Claims (6)

Water that includes a flow rate adjusting tank and a membrane separation tank that is connected downstream of the flow rate adjusting tank and in which a separation membrane module is disposed, and that drains the liquid to be treated that has flowed into the membrane separation tank through the separation membrane module A processing system,
When the treatment liquid produced by filtering the liquid to be treated through the separation membrane module after discharging the treatment liquid from the secondary side to the primary side of the separation membrane module to wash the separation membrane module, A water treatment system comprising a cleaning liquid content adjusting means for adjusting a cleaning liquid content of a processing liquid to a set value or less. The water treatment system according to claim 1,
The cleaning liquid content adjusting means is
Cleaning liquid content measuring means for measuring the cleaning liquid content of the processing liquid;
A treatment liquid return means,
When the measured value by the cleaning liquid content measuring means exceeds a set value, the processing liquid returning means is configured to return the processing liquid to at least one of the flow rate adjusting tank and the membrane separation tank. Water treatment system characterized by The water treatment system according to claim 1,
The cleaning liquid content adjusting means is
Cleaning liquid content calculating means for calculating the cleaning liquid content of the processing liquid;
Adjusting agent addition means,
Based on the cleaning liquid content calculated by the cleaning liquid content calculating means, the adjusting agent adding means is configured to add to the treatment liquid an amount of the adjusting liquid that makes the cleaning liquid content equal to or less than a set value. Water treatment system characterized by Water that includes a flow rate adjusting tank and a membrane separation tank that is connected downstream of the flow rate adjusting tank and in which a separation membrane module is disposed, and that drains the liquid to be treated that has flowed into the membrane separation tank through the separation membrane module In the treatment system, a treatment liquid produced by filtering a treatment liquid through the separation membrane module after washing the separation membrane module by flowing a washing solution from the secondary side to the primary side of the separation membrane module, A process liquid discharge method for discharging from a water treatment system,
A method for discharging a processing liquid, wherein the processing liquid is discharged after the cleaning liquid content of the processing liquid is adjusted to a set value or less. The process liquid discharge method according to claim 4,
Measure the cleaning solution content of the processing solution,
When the cleaning liquid content of the processing liquid exceeds a set value, the processing liquid is returned to at least one of the flow rate adjusting tank and the membrane separation tank, and the processing liquid is discharged after the cleaning liquid content is set to a setting value or less. A method for discharging a processing liquid. The process liquid discharge method according to claim 4,
Calculate the cleaning solution content of the treatment solution,
Based on the calculated cleaning liquid content, an adjustment agent is added in an amount that makes the cleaning liquid content equal to or lower than a set value, and the processing liquid is discharged after the cleaning liquid content is lower than the set value. Discharge method.

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