WO2020255251A1

WO2020255251A1 - Water treatment device and water treatment method

Info

Publication number: WO2020255251A1
Application number: PCT/JP2019/024091
Authority: WO
Inventors: 英二今村; 佳史林; 航吉田; 祐樹佐藤; 野田　清治
Original assignee: 三菱電機株式会社
Priority date: 2019-06-18
Filing date: 2019-06-18
Publication date: 2020-12-24
Also published as: JPWO2020255251A1; JP6644211B1; CN113993611A

Abstract

The objective of the invention is to provide a water treatment device and a water treatment method for effectively eliminating gas that has been generated while backwashing within the filter membrane or in the space between a gas exhaust unit and the filter membrane, to suppress a decrease in the filter membrane washing effect by the backwashed water. This water treatment device performs filtering whereby water to be treated is passed from a primary side to a secondary side of a membrane filter so as to be filtered, and backwashing whereby backwashing water is passed from the secondary side to the primary side of the membrane filter to wash the filter membrane, the water treatment device comprising: a backwashing water supply unit for supplying the backwashing water to the filter membrane; a detection unit for detecting gas lock due to an air bubble within the filter membrane; a control unit that causes the supply of backwashing water by the backwashing water supply unit to stop temporarily if the detection unit has detected gas lock of the filter membrane, and after a pre-determined time has elapsed causes the supply of the backwashing water by the backwashing water supply unit to resume; and a gas release unit for releasing the air bubble within the membrane filter which is induced by the control unit having caused the supply of the backwashing water by the backwashing water supply unit to stop.

Description

Water treatment equipment and water treatment method

The present invention relates to a water treatment apparatus and a water treatment method using a filtration membrane.

A membrane filtration method for producing industrial water or tap water by filtering treated water such as river water, groundwater or treated sewage water with a filtration membrane is widely adopted. The filtration method using a filtration membrane can remove suspended substances and the like in the water to be treated.

In the filtration method using a filtration membrane, objects to be removed such as turbid substances or organic substances contained in the water to be treated accumulate on the membrane surface, causing a clogging phenomenon of the filtration membrane, so that the filtration resistance of the filtration membrane increases, and eventually. Filtration cannot be performed. Therefore, in order to maintain the membrane filtration performance, back-pressure water washing that removes contaminants adhering to the membrane by pushing back-wash water, which is water such as filtered water, in the direction opposite to the filtration direction of the water to be treated. (Backwash) is performed.

At a general backwash pressure level, when gas stays in the pipe, backwash water can permeate the membrane from the inside to the outside of the filtration membrane, but stays in the pipe. The gas that had been used cannot penetrate the membrane. Therefore, gas lock occurs in which the pores of the filtration membrane are blocked by the gas, the supply of the backwash water to the filtration membrane is hindered, and the cleaning effect of the backwash water is reduced.

In the conventional technology, by providing an exhaust means in the pipe from the backwash water supply means to the filtration membrane, the gas staying in the pipe is discharged before the start of the backwash. (Citation 1)

International Publication No. 2009/008463

The water treatment apparatus described in Patent Document 1 can remove the gas staying in the pipe before the start of backwashing, but is newly added between the exhaust means to the filtration membrane or inside the filtration membrane during the backwashing treatment. Since the generated gas is pushed back by the water stream and cannot float, it is not possible to remove the newly generated gas from the exhaust means between the filtration membranes or inside the filtration membrane during the backwash treatment. Therefore, in the prior art, a gas lock is generated in the filtration membrane by the gas newly generated between the exhaust means and the filtration membrane or inside the filtration membrane during the backwash treatment, and the backwash water is supplied to the filtration membrane. Since the backwashing treatment is performed in a hindered state, the cleaning effect of the filtration membrane by the backwashing water is reduced.

The present invention has been made to solve the above problems, and efficiently removes the gas generated between the gas discharge unit and the filtration membrane or inside the filtration membrane during the backwashing treatment, and vice versa. An object of the present invention is to provide a water treatment device and a water treatment method that suppress a decrease in the cleaning effect of the filtration membrane due to washing water.

The water treatment apparatus according to the present invention has a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filtration membrane and a backwash in which the filtration membrane is washed by passing backwash water from the secondary side to the primary side of the filtration membrane. In a water treatment device that performs treatment, a backwash water supply unit that supplies backwash water to the filtration membrane, a detection unit that detects gas lock due to air bubbles inside the filtration membrane, and a detection unit are gas locks of the filtration membrane. When the backwash water supply unit temporarily stops the backwash water supply, and after a predetermined time elapses, the backwash water supply unit restarts the backwash water supply. The control unit includes a gas discharge unit that discharges air bubbles inside the filtration membrane induced by stopping the supply of backwash water by the backwash water supply unit.

The water treatment method according to the present invention includes a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filter membrane and a backwash in which the filter membrane is washed by passing backwash water from the secondary side to the primary side of the filter membrane. In the water treatment method of performing the treatment, a step of supplying backwash water to the filter membrane, a step of detecting gas lock due to air bubbles inside the filter membrane, and a step of supplying backwash water when gas lock is detected. The step of temporarily stopping the backwash water supply, the step of discharging the air bubbles inside the filter membrane guided to the gas discharge unit by temporarily stopping the backwash water supply, and the step of temporarily stopping the backwash water supply. A step of restarting the backwash water supply after a predetermined time has elapsed from the stoppage is provided.

According to the water treatment apparatus according to the present invention, the gas generated between the filtration membranes or inside the filtration membrane is efficiently removed from the gas discharge unit during the backwashing treatment, and the cleaning effect of the filtration membrane by the backwashing water is performed. Suppress the decrease in.

According to the water treatment method according to the present invention, the gas generated between the filtration membranes or inside the filtration membrane is efficiently removed from the gas discharge unit during the backwashing treatment, and the cleaning effect of the filtration membrane by the backwashing water is performed. Suppress the decrease in.

It is a figure which shows an example of the structure of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which illustrated the structure of the gas lock generation determination part and control part of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which illustrated the cross section of the filtration membrane of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which illustrated the structure of the gas discharge unit of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the example which provided the rocking part and the jet part in the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the modification of the installation position of the gas discharge unit of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is an operation flow chart of the water treatment apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the structure of the water treatment apparatus which concerns on Embodiment 2 of this invention. It is a partially enlarged view of the water treatment apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the modification of the water treatment apparatus which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments relating to the water treatment apparatus and the water treatment method disclosed in the present application will be described in detail with reference to the attached drawings. The embodiments shown below are examples, and the present invention is not limited to these embodiments.

Embodiment 1.
FIG. 1 is a diagram showing an example of the configuration of the water treatment device 100 according to the first embodiment. As shown in FIG. 1, the water treatment apparatus 100 is immersed in the water to be treated water storage tank 2 for storing the water to be treated 1 and the water to be treated 1 in the water to be treated water storage tank 2, and the water to be treated water storage tank 2 is arranged. A filter membrane 3 for filtering the water to be treated 1 inside, a filtered water tank 5 for storing the filtered water 4 filtered by the filter membrane 3, a backwash water supply unit 6 for supplying backwash water to the filter membrane 3 A gas discharge unit 7 that discharges gas generated when the backwash water supply unit 6 supplies backwash water to the filter membrane 3, a detection unit 8 that detects a gas lock of the filter membrane 3, and a water treatment device 100. A control unit 9 for controlling operation is provided.

Here, the backwash water is, for example, filtered water, a chemical solution containing ozone or hypochlorous acid, but when ozone water is used as the backwash water, the wash water containing hypochlorous acid or the like is used. Since bubbles are more likely to be generated as compared with the above, the backwash water will be described below as ozone water.

In the filtration process in which the water to be treated 1 stored in the water storage tank 2 to be treated is filtered by the filtration membrane 3 and supplied to the filtration water tank 5, the inflow side of the water 1 to be treated of the filtration membrane 3 is set as the primary side. The outflow side of the filtered water 4 of the filtration film 3 is the secondary side. Further, in the backwash treatment in which the backwash water is supplied from the backwash water supply unit 6 to the filtration membrane 3, the backwash water inflow side of the filtration membrane 3 is set as the secondary side, and the backwash water outflow side of the filtration membrane 3 is set. Is the primary side.

As shown in FIG. 1, a water to be treated water introduction pipe 11 for introducing the water to be treated 1 into the water to be treated water storage tank 2 is connected to the water to be treated water storage tank 2. One end of the connecting pipe 12 is connected to the secondary side of the filtration membrane 3, and the other end of the connecting pipe 12 is connected to the gas discharge unit 7. A filtration pipe 13 is connected to the gas discharge unit 7. A first valve 14 is arranged in the filtration pipe 13, and the filtration pipe 13 is connected to the filtration water tank 5. Further, a filtration pump 15 is installed in the filtration pipe 13 between the first valve 14 and the filtration water tank 5. A backwash pipe 16 is connected to the filtration pipe 13 between the gas discharge unit 7 and the first valve 14. A second valve 17 is installed in the backwash pipe 16, and the backwash pipe 16 is connected to the backwash water supply unit 6. Further, a backwash pump 18 is installed in the backwash pipe 16 between the second valve 17 and the backwash water supply unit 6.

Here, the water to be treated 1 may be, for example, natural water collected from a river, lake, swamp, ocean, or the like, or sewage, industrial wastewater, or the like. Further, the activated sludge may be stored in the water to be treated storage tank 2, the water to be treated 1 may be introduced, and the water to be treated 1 mixed with the activated sludge may be filtered by the filtration membrane 3.

The shape of the filtration membrane 3 is, for example, a hollow fiber type or a flat membrane type. The material of the filtration membrane 3 is, for example, an inorganic material such as ceramics, or a fluororesin-based organic material such as polyvinylidene fluoride (PVDF: Polyvinylidene DiFluoride) or polytetrafluoroethylene (PTFE: Poly Terra Fluoro Ethylene).

As shown in FIG. 1, the backwash water supply unit 6 generates ozone water by bringing the ozone gas generator 61 that generates ozone gas, the ozone gas supplied from the ozone gas generator 61, and the liquid stored inside into contact with each other. A backwash water tank 62 is provided. The ozone gas generator 61 supplies ozone gas to the backwash water tank 62 so that the liquid stored in the backwash water tank 62 has a predetermined ozone concentration.

The detection unit 8 is provided in the filtration pipe 13 between the connection point of the backwash pipe 16 connected to the filtration pipe 13 and the gas discharge unit 7, and is provided with the pressure measuring unit 81 for measuring the intermembrane differential pressure of the filtration membrane 3. A gas lock generation determination unit 82 for determining the occurrence of gas lock in the filtration membrane 3 based on the intermembrane differential pressure measured by the pressure measurement unit 81 is provided. Here, the intermembrane differential pressure is the difference in pressure between the primary side and the secondary side of the filtration membrane 3. Unless otherwise specified, the differential pressure between membranes is shown as an absolute value in the present application. When the gas lock generation determination unit 82 determines that the gas lock has occurred in the filtration membrane 3, the control unit 9 temporarily stops the supply of ozone water by the backwash water supply unit 6. Further, the installation position of the pressure measuring unit 81 is not limited to the position shown in FIG. 1 as long as the intermembrane differential pressure of the filtration membrane 3 can be measured. Here, the pressure the pressure P _A in the primary side of the filter membrane _3, when the pressure on the secondary side of the filtration membrane 3 to the pressure P _B, the differential pressure ΔP between the membranes, is calculated by the following equation (1) The value.
ΔP = P _A -P _B ... (1)

FIG. 2 is a diagram illustrating the configuration of the gas lock generation determination unit 82 and the control unit 9. FIG. 2A illustrates the configuration of the gas lock generation determination unit 82, and FIG. 2B illustrates the configuration of the control unit 9. The gas lock generation determination unit 82 can be realized by software control in which the CPU 1001a as shown in FIG. 2A executes a program stored in the memory 1002a. Further, the control unit 9 can be realized by software control in which the CPU 1001b as shown in FIG. 2B executes a program stored in the memory 1002b. The gas lock generation determination unit 82 and the control unit 9 may be configured to be realized by using the same CPU and memory.

The pressure measuring unit 81 may be configured to calculate the intermembrane differential pressure by the gas lock generation determining unit 82 using an instrument that measures the pressure in the filtration pipe 13. When the pressure measuring unit 81 measures only the pressure in the filtration pipe 13, the gas lock generation determining unit 82 performs the correction calculation in consideration of the head difference from the pressure measuring unit 81 to the water surface of the water storage tank 2 to be treated. As a result, the measured value of the pressure measuring unit 81 is converted into the intermembrane differential pressure.

Next, the operation of the water treatment device 100 according to the first embodiment will be described. The water treatment device 100 according to the first embodiment has a "filtration treatment" in which the water to be treated 1 is filtered using the filtration membrane 3 and a "filter treatment" in which the filtration treatment is interrupted and the backwash water is supplied to the filtration membrane 3. It is a water treatment device that performs "backwashing treatment".

In the water treatment apparatus 100, fouling of the filtration membrane 3, that is, blockage of pores progresses with the filtration of the water 1 to be treated by the filtration treatment. As the fouling of the filtration membrane 3 progresses, the intermembrane differential pressure of the filtration membrane 3 increases. There is a limit to the allowable intermembrane differential pressure of the filtration membrane 3, and if the filtration is continued with the intermembrane differential pressure exceeding the limit, the filtration membrane 3 may be damaged. Even if the intermembrane differential pressure is within the limit, if the filtration is continued while maintaining a high intermembrane differential pressure, fouling progresses, and it may be difficult to remove the blockage of the pores of the filtration membrane by backwashing. There is. Therefore, it is desirable to carry out the backwash treatment when a predetermined time Ta has elapsed from the start of the filtration treatment or when the predetermined intermembrane differential pressure is exceeded.

It is desirable to set the predetermined time Ta to, for example, 1 hour or more and 1 month or less. If the time interval is shorter than 1 hour, cleaning is performed in a state where fouling has not progressed so much, which is inefficient. In addition, since the backwashing treatment is frequently performed, the maintenance cost may increase. On the other hand, if washing is not performed for one month or more, irreversible fouling that cannot be removed by washing may progress.

It is desirable to set the predetermined intermembrane differential pressure to, for example, 5 kPa or more and 50 kPa or less. If the differential pressure between the membranes is lower than 5 kPa, the washing is inefficient because the washing is performed in a state where the fouling has not progressed so much. In addition, since the backwashing treatment is frequently performed, the maintenance cost may increase. On the other hand, at 50 kPa or more, irreversible fouling that cannot be removed by washing may proceed.

The backwash treatment is carried out until a predetermined time Tb elapses from the start of the backwash treatment or until a predetermined water permeability M is exceeded. Here, the water permeability M is a value calculated by the following formula (2) using the flux F, which is the amount of membrane filtration water per hour, and the intermembrane differential pressure ΔP. Here, the predetermined time Tb is preferably set to, for example, 10 minutes or more and 150 minutes or less, and the water permeability is, for example, 0.2 (m / day / kPa) or more and 0.8 (m / day / kPa). It is desirable to set as follows.
M (m / day / kPa) = F (m / day) / ΔP (kPa) ・・・ (2)

The filtration process and the backwash process may be manually and repeatedly performed by the operation manager by operating the device each time. Further, for example, it is possible to automatically and repeatedly perform each operation by using a sensor, a timer, a measuring instrument, or the like, and in this case, labor saving is possible. The effects of the present invention can be obtained unchanged by either manual or automatic methods.

Further, the execution time of the filtration process and the backwash process may be manually adjusted by the operation manager by operating the device each time. Further, for example, a timer may be provided so that the operation is performed only for a preset time, a counter or the like is provided, and the filtration operation and the backwash operation are terminated when the number of executions reaches the preset number of times. You may.

Next, the "filtration treatment" and the "backwash treatment" of the water treatment device 100 according to the first embodiment will be described in detail.

(1) Filtration Treatment In the filtration treatment, the water treatment device 100 filters the water to be treated 1 stored in the water storage tank 2 to be treated. The water to be treated 1 introduced from the water to be treated water introduction pipe 11 is stored in the water to be treated water storage tank 2. The water treatment device 100 opens the first valve 14 with the second valve 17 closed, operates the filtration pump 15, sucks the water 1 to be treated stored in the water storage tank 2 to be treated, and filters the membrane. In step 3, the water to be treated 1 is filtered. The filtered water filtered by the filtration membrane 3 is transferred to the filtered water tank 5.

(2) Backwashing treatment The backwashing treatment includes a "backwashing water generation step" and a "backwashing water backwashing step". In the following, each of the "backwash water generation step" and the "backwash water backwash step" will be described in detail.

<Backwash water generation process>
In the backwash treatment, the water treatment device 100 stops the filtration pump 15, closes the first valve 14, while operating the ozone gas generator 61, and starts supplying ozone gas to the backwash water tank 62. A liquid that can be a solvent for ozone is stored in the backwash water tank 62 in advance, and ozone water is generated by bringing the liquid into contact with ozone gas.

As the liquid that can be a solvent for ozone, for example, tap water, industrial water, pure water or ultrapure water, or a part of the filtered water 4 stored in the filtered water tank 5 may be transferred and used. Further, when the backwash water is generated in the backwash water tank 62, an acidic chemical such as hydrochloric acid or sulfuric acid or a radical scavenger (for example, carbon dioxide gas) is supplied to the liquid in the backwash water tank 62 by the ozone gas generator 61. It may be supplied at the same time as or prior to the supply of ozone gas by the ozone gas generator 61. By adding an acidic chemical or a radical scavenger to the liquid in the backwash water tank 62, it is possible to suppress the decomposition of ozone, and the effect of suppressing the generation of bubbles in ozone water can be obtained.

<Backwash water backwash process>
When the dissolved ozone concentration of the liquid in the backwash water tank 62 reaches a predetermined concentration, the supply of ozone water to the filtration membrane 3 is started. That is, the second valve 17 is opened, the backwash pump 18 operates, and the ozone water stored in the backwash water tank 62 is supplied to the filtration membrane 3 via the backwash pipe 16 and the connection pipe 12. In the process of permeating the supplied ozone water from the secondary side to the primary side of the filtration membrane 3, the fouling-causing substances (organic components such as biofilm) that block the pores of the filtration membrane 3 are chemically removed. Disassemble or physically peel off.

Oxygen gas generated by decomposition of ozone or bubbles derived from ozone itself are mixed in the connection pipe 12, the filtration pipe 13, and the backwash pipe 16 that connect the filtration membrane 3 and the backwash water supply unit 6. In some cases. Further, even when ozone water is not used as the backwash water, air bubbles may be mixed due to some other cause. When a microfiltration membrane (MF (Microfiltration Membrane) membrane) having a pore diameter of about 0.1 micrometer is used as the filtration membrane 3, for example, at a pressure (60 kPa or less) given by backwashing. Only liquids can permeate the filtration membrane 3, and bubbles such as oxygen gas or ozone gas cannot permeate the filtration membrane 3.

FIG. 3 is a diagram illustrating a cross section of the filtration membrane 3 in which gas lock occurred during the backwashing process. In FIG. 3, region A is the primary side and region B is the secondary side. Further, the region B is the inside 3a of the filtration membrane 3. Further, the bubbles inside the filtration membrane 3 3a are referred to as bubbles X. As long as the supply of ozone water is continued, the bubbles X that cause the gas lock of the filtration membrane 3 cannot float because they are pushed back by the water flow, and continue to block the filtration membrane 3. That is, when the bubbles X mixed in the backwash pipe 16 or the connection pipe 12 reach the inside 3a of the filtration membrane 3, the pores of the filtration membrane 3 may be blocked, which may hinder the flow of ozone water and impair the cleaning effect. is there.

When the gas lock generation determination unit 82 determines that the gas lock has occurred in the filtration membrane 3, the control unit 9 of the water treatment apparatus 100 according to the first embodiment supplies ozone water by the backwash water supply unit 6. It is temporarily stopped, and after a predetermined time Tc has elapsed, the supply of ozone water by the backwash water supply unit 6 is restarted. Since the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the bubbles that have reached the inside 3a of the filtration membrane 3 are guided to the gas discharge unit 7 via the connection pipe 12 and gas. It is discharged from the discharge unit 7 to the outside of the pipe. Therefore, in the water treatment device 100 according to the first embodiment, air bubbles generated between the gas discharge unit 7 and the filtration membrane 3 or inside the filtration membrane 3a during the backwashing process close the pores of the filtration membrane 3. It suppresses the deterioration of the cleaning effect due to obstructing the flow of ozone water. It is desirable that the predetermined time Tc for temporarily stopping the supply of ozone water by the backwash water supply unit 6 by the control unit 9 is set to, for example, 5 seconds or more and 600 seconds or less. The detailed configuration of the gas discharge unit 7 will be described later.

Next, a specific example of gas lock detection by the detection unit 8 will be described. The gas lock generation determination unit 82 of the detection unit 8 takes in the measurement result of the pressure measurement unit 81 every T ₁ for a predetermined time, and sets the first intermembrane differential pressure ΔP _n which is the measurement result of this time (nth time) and the previous time (nth time). The magnitude relationship is determined by comparing with the second intermembrane differential pressure ΔP _n-1 , which is the measurement result of the _n- 1th measurement). The gas lock generation determination unit 82 determines that gas lock has occurred when the differential pressure ΔP _n between the first membranes is larger than the differential pressure ΔP _n-1 between the second membranes.

Further, when determining the occurrence of gas lock more accurately, the gas lock generation determination unit 82 changes the predetermined time T ₁ and the change of the first intermembrane differential pressure ΔP _n and the second intermembrane differential pressure ΔP _n-1 . From the amount, the pressure change amount Q per unit time of the first intermembrane differential pressure ΔP _n with respect to the second intermembrane differential pressure ΔP _n-1 is calculated from the following equation (3). Unless otherwise specified, the pressure change amount Q is shown as an absolute value in the present application. In the gas lock generation determination unit 82, the pressure tends to increase when the differential pressure ΔP _n between the first membranes is larger than the differential pressure ΔP _n-1 between the second membranes and the pressure change amount Q is equal to or more than the threshold value Th. Judge that a gas lock has occurred. Incidentally, sampling intervals of T ₁ of the measurement result of the pressure measuring section 81 according to the gas lock occurrence determination unit 82 may, for example, the following 600 seconds 1 seconds, more preferably less 600 seconds 30 seconds. Further, the threshold value Th is preferably set to 0.5 (kPa / min) or more and 5.0 (kPa / min) or less. In the case of n = 1st time, the gas lock is not detected because the second intermembrane differential pressure ΔP _n-1 which is the measurement result of the _n- 1th time does not exist.
Q = (ΔP _n ₋ ΔP _n _-1 ) / T ₁ ... (3)

Further, the gas lock generation determination unit 82 can also determine the occurrence of gas lock by calculating the moving average value Z of the measurement result as the second intermembrane differential pressure ΔP _n-1 . The moving average value Z is a value calculated by the following formula (4) using m measurement results before the second intermembrane differential pressure ΔP _n-1 , which is the previous measurement result. The number of data m used to obtain the moving average value Z is, for example, 2 or more and 10 or less.
Z = Σ (P _n-1 + ・・・ + P _nm ) / m ・・・ (4)

FIG. 4 is a diagram illustrating the configuration of the gas discharge unit 7. As shown in FIG. 4, the gas discharge unit 7 is connected to the connection pipe 12 and discharges the gas-liquid separation unit 71 provided vertically above the filtration membrane 3 and the air bubbles induced in the gas-liquid separation unit 71. It has an exhaust valve 72 and an exhaust pipe 73 connected to the exhaust valve 72.

When the side connected to the gas-liquid separation portion 71 of the exhaust valve 72 is defined as the primary side and the side connected to the exhaust pipe 73 is defined as the secondary side, the exhaust valve 72 is only from the primary side to the secondary side. Moreover, it is desirable that the structure allows only gas to pass through.

The exhaust pipe 73 dissipates the gas that has passed through the exhaust valve 72 into the atmosphere. When ozone water is used as the backwash water, the exhaust pipe 73 may include an ozone removing unit for removing ozone filled with an ozone decomposition catalyst. Further, since the gas discharged from the gas discharge unit 7 is guided to the exhaust pipe 73 via the exhaust valve 72 so as to be pushed out by the backwash water, the exhaust pipe 73 is connected to the backwash water tank 62. The gas that has passed through the exhaust valve 72 may be dissipated into the backwash water tank 62, or may be dissipated into the water to be treated 1 stored in the water to be treated water storage tank 2.

Here, the shape of the connecting pipe 12 is not limited to the shape shown in FIG. 4, but when the supply of ozone water to the filtration membrane 3 by the backwash water supply unit 6 is stopped, the filtration membrane 3-2 The shape is such that the bubbles that reach the next side can float to the gas-liquid separation unit 71. When the gas-liquid separation unit 71 is provided vertically above the filtration membrane 3, the connection pipe 12 is, for example, a linear pipe that connects the filtration membrane 3 and the gas-liquid separation unit 71. Further, in order to guide the bubbles existing in the inside 3a of the filtration membrane 3 to the gas discharge unit 7, it is desirable that the connecting pipe 12 is made of a hydrophilic material having a low affinity for the bubbles. The inner surface of the connecting pipe 12 may be treated with a hydrophilic material having a low affinity for air bubbles to impart hydrophilicity, or the inner surface of the connecting pipe 12 may be treated with oxygen plasma to impart hydrophilicity. .. When the inner surface of the connecting pipe 12 is treated with oxygen plasma, the inner surface of the metal pipe such as stainless steel or iron may be treated directly, or the inner surface of the metal pipe or vinyl chloride pipe may be treated with PTFE or PFA (Perfluoroalkoxy alkane) or the like. The coated surface may be treated by applying the fluororesin of.

When the supply of ozone water from the backwash water supply unit 6 is stopped by the control unit 9, the bubbles inside the filtration membrane 3 3a are transferred to the gas-liquid separation unit 71 via the connection pipe 12. The air bubbles transferred to the gas-liquid separation unit 71 are discharged from the exhaust valve 72 via the exhaust pipe 73.

The gas discharge unit 7 is configured to discharge air bubbles inside 3a of the filtration membrane 3 when the supply of ozone water from the backwash water supply unit 6 is stopped. The backwash water supply unit 6 discharges the filtration membrane. It is preferable that the configuration is such that bubbles contained in the ozone water when the ozone water is supplied to No. 3 are also discharged. Here, as shown in FIG. 4, the diameter of the gas-liquid separation unit 71 is the diameter L1, the diameter of the connecting pipe 12 is the diameter L2, and the diameter of the filtration pipe 13 connected to the gas-liquid separation unit 71 is the diameter L3. In order to configure the gas discharge unit 7 to discharge air bubbles even when the backwash water supply unit 6 supplies ozone water to the filtration membrane 3, the diameter L1 of the gas-liquid separation unit 71 is connected to the connection pipe 12. It may be larger than the diameter L2 of the above and the diameter L3 of the filtration pipe 13 connected to the gas-liquid separation unit 71.

It is supplied by the backwash water supply unit 6 by setting the diameter L1 of the gas-liquid separation unit 71 to be larger than the diameter L2 of the connecting pipe 12 and the diameter L3 of the filtration pipe 13 connected to the gas-liquid separation unit 71. In order to promote the floating separation of the bubbles contained in the ozone water, the bubbles contained in the ozone water supplied by the backwash water supply unit 6 can be discharged from the exhaust valve 72. The diameter L1 of the gas-liquid separation unit 71, the diameter L2 of the connecting pipe 12, and the diameter L3 of the over-pipe 13 have, for example, 0.1 times the flow velocity of the gas-liquid separation unit 71 with respect to the flow velocity in the filtration pipe 13. It is preferable to set it to be 0.9 times or more and 0.9 times or less.

Next, when the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the air bubbles existing in the inside 3a of the filtration membrane 3 are caused by shaking the filtration membrane or the piping. A case of adopting a method of positively inducing the gas to the gas discharge unit 7 will be described.

FIG. 5 is a diagram showing an example in which a swing portion 19 and a jet portion 20 are provided in the water treatment device 100 according to the first embodiment. When swinging the filtration membrane 3, for example, as shown in FIG. 5, a swinging portion 19 is installed so that air can be exposed from the lower part of the filtration membrane 3, and air is exposed in the water 1 to be treated toward the filtration membrane 3. By performing the above, the gas-liquid mixed phase flow is blown to the outside of the filtration membrane 3, and the filtration membrane 3 can be shaken. Further, the same effect can be obtained by providing a jet portion 20 capable of sending a liquid such as water toward the filtration membrane 3 and spraying the liquid toward the filtration membrane 3. The rocking portion 19 shown in FIG. 5 is, for example, an aeration device, and the jet portion 20 is, for example, a pump capable of sending a liquid such as water.

Further, when the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the water to be treated 1 is passed from the primary side to the secondary side of the perfiltration membrane 3 so that the filtration membrane 3 It is also possible to adopt a method of positively guiding the air bubbles existing in the internal 3a to the gas discharge unit 7.

When passing the water to be treated 1 from the primary side to the secondary side of the filtration membrane 3, the second valve 17 is closed, the first valve 14 is opened, and the filtration pump 15 is temporarily restarted. When the restart of the filtration pump 15 is completed, the first valve 14 is closed and the second valve 17 is opened. Since restarting the filtration pump 15 for a long time causes fouling of the filtration membrane 3 due to the suspended substance in the water to be treated 1, the time for temporarily restarting the filtration pump 15 is, for example, 5 seconds or more and 300. It is desirable to set it to seconds or less.

When the detection unit 8 determines that gas lock has occurred in the filtration membrane 3 and the control unit 9 temporarily stops the supply of ozone water by the backwash water supply unit 6, the filtration membrane 3 is secondary from the primary side. When the water to be treated 1 is passed to the side, the gas discharge unit 7 may not be provided vertically above the filtration membrane 3. FIG. 6 is a diagram showing a modified example of the installation position of the gas discharge unit 7.

When it is determined by the detection unit 8 that gas lock has occurred in the filtration membrane 3 and the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the primary side to the secondary of the filtration membrane 3 Since the water to be treated 1 is passed to the side, even if the gas discharge unit 7 is not provided vertically above the filtration membrane 3 as shown in FIG. 6, the bubbles inside the filtration membrane 3 are the filtered water. 4 leads to the gas discharge unit 7. Therefore, the bubbles inside the filtration membrane 3 3a can be discharged.

When the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the treatment step of passing the water to be treated 1 from the primary side to the secondary side of the filtration membrane 3 is called filtration treatment. This is a process in which the backwashing process is alternately and repeatedly executed. As described in the prior art document (International Publication No. 2009/008463), the filtration treatment and the backwash treatment are usually automatically and repeatedly performed. Therefore, when the supply of ozone water by the backwash water supply unit 6 is temporarily stopped by the control unit 9, the treatment step of passing the water to be treated 1 from the primary side to the secondary side of the filtration membrane 3 is usually performed. It may be considered to be the same as the processing process of. However, when the control unit 9 temporarily stops the supply of ozone water by the backwash water supply unit 6, the treatment step of passing the water to be treated 1 from the primary side to the secondary side of the filtration membrane 3 is detected. This is a process to be executed when it is determined by the part 8 that gas lock has occurred in the filtration membrane 3, so that the process is different from the normal process. In the water treatment apparatus 100 according to the first embodiment, in order to detect the occurrence of gas lock of the filtration membrane 3 during the backwash treatment, the space between the gas discharge unit 7 and the filtration membrane 3 or the filtration membrane 3 during the backwash treatment The gas generated in the inner portion 3a is efficiently removed, and the deterioration of the cleaning effect of the filtration membrane 3 due to the backwashing water is suppressed.

Next, the water treatment method according to the first embodiment will be organized and explained using a flowchart. FIG. 7 is an operation flow chart of the water treatment device 100 according to the first embodiment.

When the filtration process of the water treatment device 100 is started, the first valve 14 is opened in step S1. In step S2, the filtration pump 15 is operated to suck the water 1 to be treated stored in the water storage tank 2 to be treated, and the filtration membrane 3 filters the water 1 to be treated.

In step S3, the start of the backwash treatment is determined when a predetermined time Ta elapses from the start of the filtration treatment or when the intermembrane differential pressure of the filtration membrane 3 exceeds the predetermined intermembrane differential pressure. If it is determined that the backwashing process has started, the process proceeds to step S4 and step S6.

In step S4, the filtration pump 15 is stopped. In step S5, the first valve 14 is closed. In step S6, the ozone gas generator 61 starts operation. In step S7, it is determined whether the dissolved ozone concentration of the liquid in the backwash water tank 62 is a predetermined concentration. If the concentration is equal to or higher than the predetermined concentration, the process proceeds to step S8.

When steps S5 and S7 are completed, the second valve 17 is opened in step S8. In step S9, the backwash pump 18 is operated, ozone water is supplied to the filtration membrane 3, and the backwash treatment of the filtration membrane 3 is performed.

In step S10, the end of the backwash treatment is determined when the predetermined time Tb has elapsed or when the predetermined water permeability is exceeded. If it is determined that the backwashing process is completed, the process proceeds to step S11, and if it is not determined that the backwashing process is completed, the process proceeds to step S101.

In step S101, the detection unit 8 determines whether gas lock has occurred in the filtration membrane 3. If it is determined that the gas lock has occurred, the process proceeds to step S102, and if it is determined that the gas lock has not occurred, the process proceeds to step S10.

In step S102, the backwash pump 18 is temporarily stopped. In step S103, it is determined whether a predetermined time Tc has elapsed since the backwash pump 18 was stopped. If it is determined that the predetermined time Tc has elapsed, the process proceeds to step S104. In step S104, the exhaust valve 72 of the gas discharge unit 7 discharges the air bubbles induced to the gas-liquid separation unit 71. In step S105, the backwash pump 18 is operated to restart the supply of ozone water to the filtration membrane 3.

In step S11, the backwash pump 18 is stopped. In step S12, the second valve 17 is closed. In step S13, the operation of the ozone gas generator 61 is stopped.

The water treatment apparatus 100 according to the first embodiment has a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filtration membrane and a backwash water is passed from the secondary side to the primary side of the filtration membrane to wash the filtration membrane. In the water treatment device that performs the backwash treatment, the backwash water supply unit that supplies the backwash water to the filtration membrane, the detection unit that detects gas lock due to air bubbles inside the filtration membrane, and the detection unit are the filtration membranes. When the gas lock is detected, the backwash water supply by the backwash water supply unit is temporarily stopped, and after a predetermined time has elapsed, the backwash water supply by the backwash water supply unit is restarted. It includes a control unit and a gas discharge unit that discharges air bubbles inside the filtration membrane induced by the control unit stopping the supply of backwash water by the backwash water supply unit.

Further, the detection unit of the water treatment apparatus 100 according to the first embodiment includes a pressure measurement unit that measures the intermembrane differential pressure of the filtration membrane when the backwash water is supplied to the filtration membrane by the backwash water supply unit, and a pressure. The first intermembrane differential pressure measured by the measuring unit is compared with the second intermembrane differential pressure measured by the pressure measuring unit before the measurement of the first intermembrane differential pressure, and the first is higher than the second intermembrane differential pressure. It has a gas lock determination unit for determining that gas lock has occurred in the filtration membrane when the differential pressure between the membranes is large.

Further, the detection unit of the water treatment apparatus 100 according to the first embodiment includes a pressure measurement unit that measures the intermembrane differential pressure of the filtration membrane when the backwash water is supplied to the filtration membrane by the backwash water supply unit, and a pressure. The first intermembrane differential pressure measured by the measuring unit is compared with the second intermembrane differential pressure measured by the pressure measuring unit before the measurement of the first intermembrane differential pressure, and the first is higher than the second intermembrane differential pressure. It is determined that gas lock has occurred in the filtration membrane when the intermembrane differential pressure is large and the amount of pressure change of the first intermembrane differential pressure with respect to the second intermembrane differential pressure per unit time is equal to or greater than a predetermined threshold value. It has a gas lock determination unit and a gas lock determination unit.

With the above configuration, the water treatment apparatus 100 according to the first embodiment efficiently removes the gas generated between the filtration membranes or inside the filtration membrane from the gas discharge unit during the backwashing treatment, and uses backwashing water. Suppresses the deterioration of the cleaning effect of the filtration membrane.

Further, the water treatment device 100 according to the first embodiment includes a swinging portion that swings the filtration membrane when the backwashing water supply by the backwashing water supply unit is temporarily stopped by the control unit.

Further, in the water treatment device 100 according to the first embodiment, when the supply of backwash water by the backwash water supply unit is temporarily stopped by the control unit, the water flow from the primary side of the filtration membrane toward the filtration membrane. Alternatively, it is provided with a jet section for jetting a gas-liquid mixed flow.

Further, in the water treatment device 100 according to the first embodiment, when the supply of backwash water by the backwash water supply unit is temporarily stopped by the control unit, the water treatment device 100 is treated from the primary side to the secondary side of the filtration membrane. It is characterized by allowing water to pass through.

With the above configuration, the water treatment device 100 according to the first embodiment positively guides the bubbles existing in the inside 3a of the filtration membrane 3 to the gas discharge unit 7.

The water treatment method according to the first embodiment is a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filter membrane, and a backwash water is passed from the secondary side to the primary side of the filter membrane to wash the filter membrane. In the water treatment method of performing the backwash treatment, the step of supplying the backwash water to the filter membrane, the step of detecting the gas lock due to the bubbles inside the filter membrane, and the backwash water when the gas lock is detected. The step of temporarily stopping the supply of the backwash water, the step of discharging the air bubbles inside the filter membrane guided to the gas discharge unit by temporarily stopping the supply of the backwash water, and the step of temporarily stopping the supply of the backwash water. It is provided with a step of restarting the supply of backwash water after a predetermined time has elapsed since the water was stopped.

With the above configuration, the water treatment method according to the first embodiment efficiently removes the gas generated between the gas discharge unit and the filtration membrane or inside the filtration membrane during the backwash treatment, and filters by the backwash water. Suppresses the decrease in the cleaning effect of the membrane.

Embodiment 2.
The configuration of the water treatment apparatus 200 according to the second embodiment of the present invention will be described. The same or corresponding configurations as those in the first embodiment will be omitted, and only the parts having different configurations will be described.

The water treatment device 200 according to the second embodiment has a configuration having a plurality of filtration membranes 3. When a plurality of filtration membranes 3 are installed, the same number of gas discharge units 7 as the filtration membranes 3 are provided, and each gas discharge unit 7 and each filtration membrane 3 are connected via a connection pipe 12, and the first embodiment The effect of the present invention can be obtained by performing the operation by the method shown in 1. However, when the same number of gas discharge units 7 as the plurality of filtration membranes 3 are provided, the number of parts increases, so that the production cost and the maintenance cost increase.

FIG. 8 is a diagram showing an example of the configuration of the water treatment device 200 according to the second embodiment. As shown in FIG. 8, the water treatment device 200 includes a plurality of filtration membranes 3 and a header pipe 21 having one end connected to the gas-liquid separation portion 71 of the gas discharge unit 7 and the other end connected to the filtration pipe 13. One end is connected to the secondary side of each filtration membrane 3, and the other end is provided with a plurality of connecting pipes 12 connected to a gas-liquid separation unit 71 or a header pipe 21. In the water treatment apparatus 200 according to the second embodiment, the other end of at least one of the connection pipes 12 is connected to the gas-liquid separation unit 71 of the gas discharge unit 7.

The pressure measuring unit 81 of the detection unit 8 is provided in the filtration pipe 13 between the connection point between the filtration pipe 13 and the backwash pipe 16 and the header pipe 21, and measures the intermembrane differential pressure of the entire plurality of filtration membranes 3. .. For the determination of gas lock generation by the gas lock generation determination unit 82 of the detection unit 8, the same method as the specific example described in the first embodiment can be used. The installation position of the pressure measuring unit 81 is not limited to the position shown in FIG. 8 as long as the total intermembrane differential pressure of the plurality of filtration membranes 3 can be measured.

FIG. 9 is a partially enlarged view of the water treatment apparatus 200 according to the second embodiment. As shown in FIG. 9, when the diameter of the gas-liquid separation portion 71 is the diameter L1, the diameter of the connecting pipe 12 is the diameter L2, and the diameter of the header pipe 21 is the diameter L4, the diameter L1 of the gas-liquid separation portion 71 is connected. It is larger than the diameter L2 of the pipe 12 and the diameter L4 of the header pipe 21. By making the diameter L1 of the gas-liquid separation unit 71 larger than the diameter L2 of the connecting pipe 12 and the diameter L4 of the header pipe 21, the floating separation of bubbles contained in the ozone water supplied by the backwash water supply unit 6 can be performed. In order to promote this, bubbles contained in the ozone water supplied by the backwash water supply unit 6 can be discharged from the exhaust valve 72. The diameter L1 of the gas-liquid separation unit 71, the diameter L2 of the connecting pipe 12, and the diameter L4 of the header pipe 21 have, for example, 0.1 times the flow velocity of the gas-liquid separation unit 71 with respect to the flow velocity in the header pipe 21. It is preferable to set it to be 0.9 times or more and 0.9 times or less.

When the detection unit 8 detects the gas lock of the filtration membrane 3, the control unit 9 temporarily stops the supply of ozone water by the backwash water supply unit 6, as in the water treatment device 100. When the supply of ozone water is temporarily stopped, air bubbles inside the filtration membrane 3A are guided to the gas-liquid separation unit 71 and discharged from the exhaust valve 72. Bubbles inside the

filtration membranes

3B, 3C, and 3D may be guided to the header tube 21 and stay in the header tube 21 as bubbles Y. Therefore, the header tube 21 may be made of a hydrophilic material having a low affinity for bubbles, and the header tube 21 may be formed so that the bubbles induced in the header tube 21 are guided to the gas-liquid separation portion 71. preferable. However, when it is difficult to make the shape of the header pipe 21 into a shape for guiding the air bubbles guided to the header pipe 21 to the gas-liquid separation portion 71 due to the design of the water treatment device, as shown in FIG. The diameter L1 of the gas-liquid separation portion 71 may be made larger than the diameter L2 of the connecting pipe 12 and the diameter L4 of the header pipe 21. When the diameter L1 of the gas-liquid separation unit 71 is made larger than the diameter L2 of the connecting pipe 12 and the diameter L4 of the header pipe 21, the air bubbles Y induced in the header pipe 21 are generated by the control unit 9 in the backwash water supply unit 6. The bubbles Y guided to the gas-liquid separation unit 71 by resuming the supply of ozone water and induced to the gas-liquid separation unit 71 are discharged from the exhaust valve 72 by levitation separation.

Therefore, the water treatment device 200 according to the second embodiment is the same as the water treatment device 100 of the first embodiment by performing the same operation as the water treatment device 100 of the first embodiment in both the filtration step and the backwashing step. Play the effect of.

FIG. 10 is a diagram showing a modified example of the water treatment device 200 according to the second embodiment. In the example shown in FIG. 10, a plurality of header pipes 21 to which a plurality of connecting pipes 12 are connected are provided, a gas discharge unit 7 is connected to one end of each of the plurality of header pipes 21, and the other end of each is a collecting pipe. It is connected to 22. The collecting pipe 22 is connected to the filtration pipe 13, and other configurations are the same as those of the water treatment device 200 according to the second embodiment.

The example shown in FIG. 10 is the same as the water treatment apparatus 200 according to the second embodiment except that a plurality of header pipes 21 are provided and the plurality of header pipes 21 are connected to the collecting pipe 22. By performing the same operation as the water treatment device 200 according to the second embodiment, the same effect as the water treatment device 200 according to the second embodiment can be obtained.

The water treatment device 200 according to the second embodiment is provided with a plurality of filtration membranes, and the gas discharge unit has a gas-liquid separation unit in which air bubbles inside the filtration membrane are induced and a gas-liquid separation unit in which air bubbles are induced in the gas-liquid separation unit. The water treatment device has an exhaust valve for discharging, and one end is connected to a gas-liquid separation part and the other end is connected to a pipe connected to a backwash water supply part. A plurality of connecting pipes connected to the secondary side of the filtration membrane and the other end connected to the gas-liquid separation part or the gas discharge part, and at least one of the connection pipes has the other end of the gas-liquid separation part. By temporarily stopping the supply of backwash water by the backwash water supply unit, the air bubbles inside the filtration membrane are guided to the header tube or the gas-liquid separation part, and are guided to the header tube. The generated bubbles are characterized in that they are guided to the gas-liquid separation unit by the control unit restarting the supply of the backwash water by the backwash water supply unit.

Further, the diameter of the gas-liquid separation portion of the water treatment apparatus 200 according to the second embodiment is larger than the diameter of the connecting pipe and the header pipe.

With the above configuration, the water treatment apparatus 200 according to the second embodiment efficiently removes the gas generated between the filtration membranes or inside the filtration membrane from the gas discharge unit during the backwashing treatment, and uses backwashing water. Suppresses the deterioration of the cleaning effect of the filtration membrane.

Further, since it is not necessary to provide the same number of gas discharge units 7 as the plurality of filtration membranes 3, it is possible to suppress an increase in production cost and maintenance cost.

In the first and second embodiments, the backwash water is described as ozone water, but the backwash water is not limited to ozone water. As the backwash water, for example, filtered water or a chemical solution containing hypochlorous acid may be used. When a chemical solution containing hypochlorous acid is used as the backwash water, the cost of the backwash water can be reduced as compared with the case where ozone water is used as the backwash water.

In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

100,200 Water treatment device 1 Water to be treated 2 Water to be treated 2 Storage tank 3 Filter film 4 Filtered water 5 Filtered water tank 6 Backwash water supply unit 7 Gas discharge unit 8 Detection unit 9 Control unit 11 Processed water introduction pipe 12 Connection pipe 13 Filter pipe 14 1st valve 15 Filter pump 16 Backwash pipe 17 2nd valve 18 Backwash pump 19 Swing part 20 Jet flow part 21 Header pipe 22 Collecting pipe 61 Ozone gas generator 62 Backwash water tank 71 Gas-liquid separation part 72 Exhaust Valve 73 Exhaust pipe 81 Pressure measurement unit 82 Gas lock

generation determination unit

1001a, 1001b CPU
1002a, 1002b memory

Claims

Water treatment that performs a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filtration membrane and a backwash treatment in which the filtration membrane is washed by passing backwash water from the secondary side to the primary side of the filtration membrane. In the device
A backwash water supply unit that supplies the backwash water to the filtration membrane,
A detection unit that detects gas lock due to air bubbles inside the filtration membrane,
When the detection unit detects the gas lock of the filtration membrane, the backwash water supply by the backwash water supply unit is temporarily stopped, and after a predetermined time elapses, the backwash water supply is performed. A control unit that restarts the supply of the backwash water by the unit,
A gas discharge unit that discharges the bubbles inside the filtration membrane induced by the control unit stopping the supply of the backwash water by the backwash water supply unit.
A water treatment device equipped with.
A plurality of the filtration membranes are provided,
The gas discharge unit has a gas-liquid separation portion in which the bubbles are induced inside the filtration membrane, and an exhaust valve for discharging the bubbles guided to the gas-liquid separation portion.
The water treatment device
A header pipe having one end connected to the gas-liquid separation unit and the other end connected to a pipe connected to the backwash water supply unit.
A plurality of connecting pipes having one end connected to the secondary side of each of the filtration membranes and the other end connected to the gas-liquid separator or the header pipe.
With
At least one of the connecting pipes has the other end connected to the gas-liquid separation portion.
When the control unit temporarily stops the supply of the backwash water by the backwash water supply unit, the bubbles inside the filtration membrane are guided to the header pipe or the gas-liquid separation unit, and the gas-liquid separation unit is guided. Claim 1 is characterized in that the air bubbles guided to the header pipe are guided to the gas-liquid separation unit by the control unit restarting the supply of the backwash water by the backwash water supply unit. The water treatment apparatus according to.
The water treatment apparatus according to claim 2, wherein the diameter of the gas-liquid separation portion is larger than the diameter of the connecting pipe and the header pipe.
Any one of claims 1 to 3 including a swinging portion that swings the filtration membrane when the backwashing water supply by the backwashing water supply unit is temporarily stopped by the control unit. The water treatment apparatus described in the section.
When the backwash water supply unit temporarily stops the supply of the backwash water by the control unit, a jet flow that ejects a water flow or a gas-liquid mixed flow from the primary side of the filtration membrane toward the filtration membrane. The water treatment apparatus according to any one of claims 1 to 4, further comprising a unit.
When the supply of the backwash water by the backwash water supply unit is temporarily stopped by the control unit, the water to be treated is passed from the primary side to the secondary side of the filtration membrane. The water treatment apparatus according to any one of claims 1 to 5.
The detection unit
A pressure measuring unit that measures the intermembrane differential pressure of the filtration membrane when the backwash water is supplied to the filtration membrane by the backwash water supply unit.
The difference between the first membranes measured by the pressure measuring unit is compared with the differential pressure between the second membranes measured by the pressure measuring unit before the measurement of the differential pressure between the first membranes. A gas lock determination unit that determines that gas lock has occurred in the filtration membrane when the differential pressure between the first membranes is larger than the pressure.
The water treatment apparatus according to any one of claims 1 to 6.
The detection unit
A pressure measuring unit that measures the intermembrane differential pressure of the filtration membrane when the backwash water is supplied to the filtration membrane by the backwash water supply unit.
The difference between the first membranes measured by the pressure measuring unit is compared with the differential pressure between the second membranes measured by the pressure measuring unit before the measurement of the differential pressure between the first membranes. The filtration is performed when the differential pressure between the first membranes is larger than the pressure and the amount of change in pressure of the differential pressure between the first membranes with respect to the differential pressure between the second membranes per unit time is equal to or greater than a predetermined threshold value. A gas lock determination unit that determines that gas lock has occurred on the membrane,
The water treatment apparatus according to any one of claims 1 to 6.
Water treatment that performs a filtration treatment in which the water to be treated is passed from the primary side to the secondary side of the filtration membrane and a backwash treatment in which the filtration membrane is washed by passing backwash water from the secondary side to the primary side of the filtration membrane. In the method
The step of supplying the backwash water to the filtration membrane and
The step of detecting gas lock due to air bubbles inside the filtration membrane and
When the gas lock is detected, the step of temporarily stopping the supply of the backwash water and
A step of discharging the bubbles inside the filtration membrane induced to the gas discharge unit by temporarily stopping the supply of the backwash water, and a step of discharging the bubbles.
A step of temporarily stopping the supply of the backwash water and then restarting the supply of the backwash water after a predetermined time has elapsed.
A water treatment method that comprises.