JP2011235235A - Water treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system which prevents a filter membrane from being oxidized and deteriorated by oxidants and also prevents the membrane from being clogged by slime.SOLUTION: The water treatment system 1 includes: a raw water line L1 through which raw water W1 containing oxidants circulates; an oxidant remover 3 which is connected to the line L1 and removes the oxidants from the water W1; a membrane separator 4 which is positioned at the end of the downstream of the line L1 and separates the water W1 into permeated water W2 and condensed water W3 through a filter membrane; and a control 6 for removing and controlling oxides, which controls the remover 3 to temporarily restrict a treatment for removing the oxidants from the water W1 for sterilizing the membrane.

Description

  The present invention relates to a water treatment system that separates raw water containing an oxidizing agent into permeated water and concentrated water using a filtration membrane.

  Conventionally, a water treatment system that separates raw water containing impurities such as dissolved salts into permeated water and concentrated water using a filtration membrane is known. In such a water treatment system, an oxidizing agent such as sodium hypochlorite is added to the raw water in advance in order to prevent microorganisms such as bacteria from propagating in the raw water line through which the raw water circulates or in the filtration membrane. Sterilization is performed.

However, if such an oxidizing agent (residual chlorine) is contained in the raw water, the filtration membrane may be oxidized by the oxidizing agent and the filtering ability may be deteriorated at an early stage.
In contrast, a water treatment system is provided that produces permeate while removing the oxidant in the raw water before the raw water is introduced into the filtration membrane and monitoring the concentrated water so that the concentration of the oxidant is not detected. (For example, refer to Patent Document 1).

JP-A-9-57076

  However, the water treatment system described in Patent Document 1 is operated in a state where an oxidizing agent having a sterilizing ability is removed from raw water. Therefore, depending on the quality of the raw water, there is a problem that various bacteria propagate in the filter membrane and slime is formed, and the filter membrane is blocked by this slime and water treatment cannot be performed.

  An object of this invention is to provide the water treatment system which can suppress the oxidative degradation of the filtration membrane by an oxidizing agent, and can suppress the obstruction | occlusion of the filtration membrane resulting from a slime.

  The present invention includes a raw water line through which raw water containing an oxidant flows, an oxidant removing means connected to the raw water line for removing the oxidant from the raw water, and provided at an end on the downstream side of the raw water line. Separation means for separating the permeated water and concentrated water by a filtration membrane, and when the filtration membrane is sterilized, the oxidant removal means is controlled so as to temporarily limit the treatment for removing the oxidant from the raw water The present invention relates to a water treatment system comprising an oxidant removal treatment control means.

  Further, the oxidizing agent removing means is a reducing agent adding device for adding a reducing agent to the raw water containing the oxidizing agent, and the oxidizing agent removing process control means is configured to add the reducing agent to the raw water by the reducing agent adding device. It is preferable that the reducing agent addition control device be temporarily stopped.

  Further, it is preferable that the oxidant removal processing control means stop adding the reducing agent to the raw water during a flushing period in which the filtration membrane is washed by flowing the raw water on the primary surface of the filtration membrane. .

  Further, the oxidant removal processing control means preferably stops adding the reducing agent to the raw water for a predetermined time from the start of the flushing, and then adds the reducing agent to the raw water until the completion of the flushing. .

  Further, the oxidant removing means is an activated carbon filtration treatment device provided in the raw water line and adsorbing and removing organic components and oxidants contained in the raw water with activated carbon, and the oxidant removal treatment control means includes the A bypass line that connects the upstream side and the downstream side of the activated carbon filtration device in the raw water line, a bypass valve that opens and closes the bypass line, and a bypass valve control device that controls opening and closing of the bypass valve. preferable.

  Moreover, it is preferable that the said oxidizing agent removal process control means opens the said bypass valve in the implementation period of the flushing which wash | cleans this filtration membrane by flowing raw | natural water on the surface of the primary side of the said filtration membrane.

  Further, it is preferable that the oxidant removal processing control means opens the bypass valve for a predetermined time from the start of the flushing, and then closes the bypass valve until the completion of the flushing.

  Moreover, it is preferable to further include an oxidant addition unit for adding an oxidant to the downstream side of the oxidant removal unit in the raw water line or the membrane separation unit.

  The filtration membrane is preferably one of a reverse osmosis membrane, an ultrafiltration membrane, and a microfiltration membrane.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress the oxidative degradation of the filtration membrane by an oxidizing agent, the water treatment system which can suppress the obstruction | occlusion of the filtration membrane resulting from a slime can be provided.

It is a lineblock diagram showing water treatment system 1 of a 1st embodiment of the present invention. It is a time chart which shows the control method of the reducing agent addition pump 3b. It is a time chart which shows the control method of the reducing agent addition pump 3b of 2nd Embodiment of this invention. It is a block diagram which shows 1A of water treatment systems of 3rd Embodiment of this invention. 3 is a time chart showing a method for controlling the bypass valve 8. It is a time chart which shows the control method of the bypass valve 8 of 4th Embodiment of this invention. It is a block diagram which shows the water treatment system 1B of 5th Embodiment of this invention. It is a block diagram which shows 1 C of water treatment systems of 6th Embodiment of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. Drawing 1 is a lineblock diagram showing water treatment system 1 of a 1st embodiment of the present invention. The raw water W1 to be purified by the water treatment system 1 of the first embodiment shown in FIG. 1 contains an oxidizing agent (sterilizing component) such as sodium hypochlorite for sterilizing microorganisms such as bacteria. The water treatment system 1 separates the raw water W1 containing this oxidant into permeated water W2 and concentrated water W3 using a filtration membrane.

As shown in FIG. 1, a water treatment system 1 includes a raw water line L1, a raw water pump 2, a reducing agent addition device 3 as an oxidant removing means, a reverse osmosis membrane device 4 as a membrane separation means, and permeate water. Mainly a treated water line L2 through which W2 circulates, a concentrated water line L3 through which the concentrated water W3 circulates, a treated water tank 5 for storing the permeated water W2, and a control device 6 as an oxidant removal treatment control means. Composed.
In addition, the “line” in this specification is a general term for a line capable of flowing a fluid such as a flow path, a path, and a pipeline. The permeated water W2 produced by the reverse osmosis membrane device 4 is also referred to as “treated water”.
Hereinafter, each part of the water treatment system 1 will be described in detail.

  In the raw water line L1, raw water W1 containing an oxidizing agent flows. The raw water pump 2 is provided in the raw water line L1. The raw water pump 2 sends the raw water W1 supplied from the upstream side of the raw water line L1 toward the reverse osmosis membrane device 4. The raw water pump 2 is electrically connected to a control device 6 (described later). Operation (drive and stop) of the raw water pump 2 is controlled by a control device 6 (described later).

The reducing agent addition device 3 is connected to an addition point J1 downstream of the raw water pump 2 in the raw water line L1. The reducing agent adding device 3 adds the reducing agent to the raw water W1 containing the oxidizing agent. The reducing agent addition device 3 includes a reducing agent storage unit 3a and a reducing agent addition pump 3b.
The reducing agent storage unit 3a stores a reducing agent. Examples of the reducing agent include sodium bisulfite. Sodium bisulfite removes the oxidizing agent from the raw water W1 by reducing hypochlorite ions as oxidizing agents remaining in the raw water W1 to chloride ions.

  The reducing agent addition pump 3b sends the reducing agent stored in the reducing agent storage unit 3a from the addition point J1 of the raw water line L1 to the raw water W1 and adds it. The reducing agent addition pump 3b is electrically connected to a control device 6 (described later). Operation (drive and stop) of the reducing agent addition pump 3b is controlled by a control device 6 (described later).

  The reverse osmosis membrane device 4 is provided at the downstream end of the raw water line L1. The reverse osmosis membrane device 4 separates the raw water W1 into a high purity permeated water W2 and a concentrated water W3 containing a large amount of impurities by a reverse osmosis membrane (hereinafter also referred to as “RO membrane”) as a filtration membrane. The reverse osmosis membrane device 4 includes a pressurization pump 4a provided on the upstream side and an RO membrane module 4b provided on the downstream side.

  The pressurizing pump 4a pressurizes the raw water W1 supplied from the raw water line L1 and sends it to the RO membrane module 4b. The RO membrane module 4b includes a number of RO membranes (not shown) that remove impurities such as dissolved salts. The RO membrane is a membrane capable of filtering a molecular weight of about several tens, and is configured as a low fouling membrane. The RO membrane module 4b is housed in a housing (not shown) called a vessel.

  Moreover, the reverse osmosis membrane apparatus 4 is comprised so that a RO membrane can be wash | cleaned by flowing the raw water W1 along the surface of the primary side of a RO membrane (it is made to contact). Hereinafter, this cleaning of the RO membrane is referred to as “flushing”. Flushing is performed at a time (time) set in advance or when it is determined that it is necessary to perform the operation based on the contamination level of the RO membrane, such as when water supply is stopped or when the permeation flux decreases. The pollution degree of the RO membrane is obtained, for example, by measuring the differential pressure between the primary side and the secondary side of the RO membrane with a differential pressure gauge (not shown).

  The reverse osmosis membrane device 4 is connected with a treated water line L2 and a concentrated water line L3. The permeated water W2 produced by the reverse osmosis membrane device 4 flows through the treated water line L2. The downstream end of the treated water line L2 is connected to the treated water tank 5. Concentrated water W3 produced by the reverse osmosis membrane device 4 flows through the concentrated water line L3. The concentrated water line L3 discharges (blows) the concentrated water W3 out of the system. The concentrated water W3 is blown, for example, when flushing is performed. The treated water tank 5 is provided at the downstream end of the treated water line L2. The treated water tank 5 stores the permeated water W2 produced by the reverse osmosis membrane device 4.

  Although not shown in the drawing, the raw water line L1, the treated water line L2, and the concentrated water line L3 are opened and closed by a pump for sending the raw water W1, the permeated water W2, or the concentrated water W3, and a line (flow path). An appropriate valve or the like is provided. These pumps, valves, and the like are also electrically connected to the control device 6, and their operation and opening / closing are controlled by the control device 6.

  The control device 6 is electrically connected to the reducing agent addition pump 3b of the reducing agent addition device 3. The control device 6 controls the operation (drive and stop) of the reducing agent addition pump 3b and functions as a reducing agent addition control device. According to this control device 6, the addition of the reducing agent to the raw water W1 can be temporarily stopped.

  The control device 6 is electrically connected to the raw water pump 2, the pressurization pump 4a of the reverse osmosis membrane device 4, and other pumps and valves (not shown). The control device 6 controls the operation of the raw water pump 2 and the like, and controls the opening and closing of valves (not shown).

  Although not shown in the figure, a filtration device that normally captures and removes suspended substances contained in the raw water W1 by the sieve effect of the filter medium is provided on the upstream side of the reverse osmosis membrane device 4. Various filtration processing apparatuses are selected according to the substance to be removed in the raw water W1. Examples of the filtration apparatus include a sand filtration apparatus and an iron removal manganese removal apparatus.

  The sand filtration apparatus captures and removes suspended substances such as fine particles contained in the raw water W1 with a filter medium. The iron removal manganese removal apparatus captures and removes dissolved iron and dissolved manganese together with suspended substances such as fine particles contained in the raw water W1 with a filter medium. When the pretreatment of the raw water W1 is performed in these filtration devices, an oxidizing agent such as sodium hypochlorite is added upstream of the reducing agent addition point J1 in the raw water line L1.

  Next, operation | movement of the water treatment system 1 is demonstrated, referring FIG.1 and FIG.2. FIG. 2 is a time chart showing a control method of the reducing agent addition pump 3b. FIG. 2 also shows the operating state of the reverse osmosis membrane device 4. In FIG. 2, symbols T1, T2, and T3 indicate time. Time T1 is the time when the reverse osmosis membrane device 4 (water treatment system 1) starts water supply and the time when the reducing agent addition pump 3b starts operation. Time T2 is the time when the flushing starts and the time when the reverse osmosis membrane device 4 ends the water supply. In the present embodiment, the time T2 is a time at which the operation of the reducing agent addition pump 3b is stopped. Time T3 is a time at which the flushing is finished, and a time at which the reverse osmosis membrane device 4 enters the water supply standby state.

  First, a control method during normal operation in which the RO membrane of the reverse osmosis membrane device 4 is not sterilized will be described. As shown in FIG. 2, when a water supply request is made to the water treatment system 1 (reverse osmosis membrane device 4) at time T1, the control device 6 drives (operates) the raw water pump 2 and the reducing agent addition pump 3b. ) Then, the raw water W1 containing the oxidizing agent flows through the raw water line L1 toward the reverse osmosis membrane device 4.

  For example, sodium bisulfite as a reducing agent is added to the raw water W1 flowing through the raw water line L1 from the reducing agent reservoir 3a by driving the reducing agent addition pump 3b. Sodium bisulfite reduces hypochlorite ions as oxidizing agents remaining in the raw water W1 to chloride ions. Thereby, the oxidizing agent that degrades the RO membrane is removed from the raw water W1.

  Then, the raw water W1 from which the oxidizing agent has been removed is introduced into the reverse osmosis membrane device 4. The raw water W1 is separated into permeated water W2 and concentrated water W3 by the RO membrane of the reverse osmosis membrane device 4. Thereby, the permeated water W2 from which impurities such as dissolved salts have been removed is produced. As described above, the oxidizing agent is removed from the raw water W1 introduced into the RO membrane. Therefore, the deterioration of the RO membrane due to the oxidizing action of this oxidizing agent is suppressed.

  The permeated water W2 produced by the reverse osmosis membrane device 4 is introduced into the treated water tank 5 via the treated water line L2, and stored in the treated water tank 5. The treated water W2 stored in the treated water tank 5 is distributed to a demand destination (not shown). Further, the concentrated water W3 produced by the reverse osmosis membrane device 4 flows through the concentrated water line L3 and is discharged out of the system.

  Next, a control method when the RO membrane of the reverse osmosis membrane device 4 is sterilized will be described. The sterilization of the RO membrane in the present embodiment uses the sterilization action of an oxidizing agent such as sodium hypochlorite contained in the raw water W1. That is, the controller 6 temporarily removes the oxidizing agent from the raw water W1 by temporarily stopping the addition of the reducing agent (operation of the reducing agent addition pump 3b) to the raw water W1 containing the oxidizing agent. To stop. As a result, raw water W1 containing the oxidizing agent (raw water W1 having sterilizing ability) is supplied to the RO membrane, and the RO membrane is sterilized by the sterilizing action of the oxidizing agent.

  Specifically, as shown in FIG. 2, the sterilization of the RO membrane is performed in accordance with the flushing period (from time T2 to time T3) of the reverse osmosis membrane device 4. The control device 6 stops the operation of the reducing agent addition pump 3b at the time T2 when the flushing is started, and then continues this operation stop state until the time T3 when the flushing is finished. As a result, the raw water W1 containing the oxidizing agent is supplied to the RO membrane as cleaning water at the time of flushing, and comes into contact with the surface on the primary side of the RO membrane. Therefore, the RO membrane is sterilized by the oxidizing action of the oxidizing agent contained in the raw water W1. Therefore, the proliferation of germs on the primary surface of the RO membrane is suppressed, and the formation of slime is suppressed.

  Moreover, as shown in FIG. 2, the control apparatus 6 stops the water supply by the reverse osmosis membrane apparatus 4 during the flushing implementation period (period from time T2 to time T3). When the water supply is in a standby (stopped) state, the control device 6 also stops the operation of the reducing agent addition pump 3b. In the present embodiment, the operation stop state of the reducing agent addition pump 3b is continued after time T3. When a water supply request is made again to the water treatment system 1, the above control is repeated.

According to the water treatment system 1 of 1st Embodiment demonstrated above, each effect shown below is show | played.
The water treatment system 1 of 1st Embodiment is the reverse osmosis membrane which isolate | separates raw | natural water W1 into the permeated water W2 and the concentrated water W3 with RO membrane by adding a reducing agent to the raw water W1 containing an oxidizing agent. The apparatus 4 and the controller 6 that controls the reducing agent addition pump 3b so as to temporarily stop the addition of the reducing agent to the raw water W1 by the reducing agent addition device 3 when the RO membrane is sterilized are provided.

  Therefore, the reduction treatment for removing the oxidizing agent from the raw water W1 can be temporarily stopped, and the raw water W1 containing the oxidizing agent (raw water W1 having sterilizing ability) is introduced into the RO membrane of the reverse osmosis membrane device 4. Can do. As a result, the RO membrane is sterilized only when necessary by the oxidizing action of the oxidizing agent, and slime formation is suppressed. Therefore, it is possible to suppress the oxidative deterioration of the filtration membrane due to the oxidizing agent, and it is possible to suppress the blockage of the RO membrane due to slime (decrease in the amount of permeated water due to the clogging of the RO membrane).

By the way, although the RO membrane is sterilized by the oxidizing action of the oxidizing agent, the RO membrane may be deteriorated to some extent by the oxidizing action of the oxidizing agent.
However, the water treatment system 1 of this embodiment gives priority to the suppression of slime formation over the suppression of the oxidative deterioration of the RO membrane by the oxidizing agent. Therefore, in the case where there is a large amount of slime formation in the RO membrane due to the quality of the raw water W1, and the RO membrane is more likely to be blocked by the formation of slime than the deterioration due to oxidation of the oxidizing agent, the RO membrane Can be avoided. Therefore, as a result, the lifetime of the RO membrane can be extended.

  Moreover, in the water treatment system 1 of 1st Embodiment, the control apparatus 6 stops addition of the reducing agent to the raw | natural water W1 in the implementation period of flushing. Therefore, the RO membrane can be sterilized using the period during which water supply is stopped. Therefore, when there is much water supply demand, water supply can be ensured.

  Next, another embodiment of the present invention will be described. The other embodiments will be described mainly with respect to differences from the first embodiment, and the same configurations as those of the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted. For the points not specifically described in other embodiments, the description of the first embodiment is appropriately applied or incorporated.

[Second Embodiment]
Although the water treatment system of 2nd Embodiment of this invention is equipped with the structure similar to the water treatment system 1 of the said 1st Embodiment, the water treatment system 1 of 1st Embodiment is the reducing agent addition pump 3b. The control method is different. Therefore, with reference to FIG. 1 showing the water treatment system 1 of the first embodiment, a control method of the reducing agent addition pump 3b in the second embodiment will be described with reference to FIG. FIG. 3 is a time chart showing a control method of the reducing agent addition pump 3b according to the second embodiment of the present invention. FIG. 3 also shows the operating state of the reverse osmosis membrane device 4.

  In FIG. 3, symbols T1 to T4 indicate time. In the operation of the reverse osmosis membrane device 4, the time T1 to the time T3 are the same as the case shown in FIG. 2 of the first embodiment. In the operation of the reducing agent addition pump 3b, time T4 is the time when the operation of the reducing agent addition pump 3b is started. In addition, time T3 in the present embodiment is also a time at which the operation of the reducing agent addition pump 3b is stopped.

  The control method during normal operation in which the RO membrane of the reverse osmosis membrane device 4 is not sterilized is the same as that in the case of the first embodiment, and thus redundant description is omitted.

  When the RO membrane is sterilized, as shown in FIG. 3, the RO membrane is sterilized in accordance with the flushing timing of the reverse osmosis membrane device 4. The control device 6 stops the operation of the reducing agent addition pump 3b at the time T2 when the flushing is started, and then continues this operation stop state for a predetermined time until the time T4. As a result, the raw water W1 containing the oxidizing agent is introduced into the RO membrane as cleaning water at the time of flushing, and comes into contact with the primary surface of the RO membrane. Therefore, the RO membrane is sterilized by the oxidizing action of the oxidizing agent contained in the raw water W1.

  And the control apparatus 6 restarts the driving | operation of the reducing agent addition pump 3b at the time T4, and stops the driving | operation of the reducing agent addition pump 3b at the time T3. That is, during the period from time T4 to time T3, the oxidizing agent contained in the raw water W1 is reduced by the reducing agent added (sent out) from the reducing agent addition pump 3b. Therefore, the oxidizing agent is removed from the raw water W1. Therefore, in the period from time T4 to time T3, the raw water W1 from which the oxidant has been removed is introduced into the RO membrane as cleaning water at the time of flushing, and comes into contact with the primary surface of the RO membrane.

  As a result, in the vessel, the raw water W1 from which the oxidant has been removed remains. Therefore, even when the water supply standby time is long, the RO membrane is not exposed to the raw water W1 containing the oxidizing agent for a long time. Therefore, the RO membrane is prevented from being deteriorated by the oxidizing action of the oxidizing agent.

According to the water treatment system of the second embodiment described above, the same effects as the water treatment system of the first embodiment are exhibited, and the following effects are exhibited.
In the water treatment system of the second embodiment, the control device 6 stops adding the reducing agent to the raw water W1 for a predetermined time (from time T2 to time T4) from the start of the flushing.

  In the water treatment system 1 (see FIG. 1) of the first embodiment, the water supply by the reverse osmosis membrane device 4 is in a standby state from time T3 when the flushing is finished. Therefore, the operation of the reducing agent addition pump 3b remains stopped after time T3. Therefore, the raw water W1 containing the oxidant remains in the vessel after time T3, and if the water supply standby time becomes longer than expected, there is a possibility that the RO membrane is deteriorated by the oxidizing action of the oxidant. is there.

  However, in the water treatment system of the second embodiment, after the RO membrane is sterilized for a predetermined time, the oxidant is removed from the raw water W1, and thus the RO membrane is not exposed to the oxidant. Therefore, even if it is a case where water supply waiting time becomes long, it can suppress that RO membrane deteriorates by the oxidizing action of an oxidizing agent.

[Third Embodiment]
The water treatment system 1 of the first embodiment and the water treatment system of the second embodiment include a reducing agent addition device 3 as an oxidant removing unit and a control device 6 as an oxidant removal processing control unit. A water treatment system 1A according to the third embodiment is different from the reducing agent addition device 3 and the control device 6 in that an activated carbon filtration treatment device 7 as an oxidant removal unit, a bypass line L4 as an oxidant removal treatment control unit, and a bypass valve 8 and the control device 6A are mainly different.

Hereinafter, a water treatment system 1A according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a configuration diagram illustrating a water treatment system 1A according to a third embodiment of the present invention.
As shown in FIG. 4, the water treatment system 1A includes a raw water line L1, a raw water pump 2, an activated carbon filtration device 7, a reverse osmosis membrane device 4, a treated water line L2, a concentrated water line L3, a treatment The water tank 5, the bypass line L4, the bypass valve 8, and the control device 6A are mainly configured.

  The raw water line L1, the raw water pump 2, the reverse osmosis membrane device 4, the treated water line L2, the concentrated water line L3, and the treated water tank 5 of the water treatment system 1A of the second embodiment are the same as the water treatment system 1 ( 1), the raw water line L1, the raw water pump 2, the reverse osmosis membrane device 4, the treated water line L2, the concentrated water line L3, and the treated water tank 5 are configured in the same manner, and redundant description is given. Is omitted.

  As shown in FIG. 4, the activated carbon filtration device 7 is provided on the downstream side of the raw water pump 2 in the raw water line L1. The activated carbon filtration device 7 removes oxidants such as sodium hypochlorite, organic substances, chromaticity components, odor components and the like together with suspended substances contained in the raw water W1 with a filter medium made of an adsorbent. Usually, particulate or fibrous activated carbon is used as the adsorbent.

The bypass line L4 connects the upstream connection point J2 and the downstream connection point J3 of the activated carbon filtration device 7 in the raw water line L1.
The bypass valve 8 is provided in the bypass line L4 and opens and closes the bypass line L4. The bypass valve 8 is electrically connected to a control device 6A (described later). Opening and closing of the bypass valve 8 is controlled by a control device 6A (described later).

  The control device 6A is electrically connected to the bypass valve 8. The control device 6A controls the opening and closing of the bypass valve 8, and functions as a bypass valve control device. According to this control device 6A, by opening the bypass valve 8, a part of the raw water W1 flows into the bypass line L4 and can be supplied to the reverse osmosis membrane device 4 without being distributed to the activated carbon filtration device 7. it can.

  The control device 6A is electrically connected to the raw water pump 2, the pressurizing pump 4a of the reverse osmosis membrane device 4, and other pumps and valves (not shown). The control device 6A controls the operation of the raw water pump 2 and the like and the opening and closing of valves (not shown).

Next, operation | movement of 1 A of water treatment systems is demonstrated, referring FIG.4 and FIG.5. FIG. 5 is a time chart showing a method for controlling the bypass valve 8. FIG. 5 also shows the operating state of the reverse osmosis membrane device 4.
In FIG. 5, symbols T1 to T3 indicate time. In the operation of the reverse osmosis membrane device 4, the time T1 to the time T3 are the same as the case shown in FIG. 2 of the first embodiment. In the operation of the bypass valve 8, time T1 and time T3 are times when the bypass valve 8 is closed. Time T2 is a time when the bypass valve 8 is opened.

First, a control method during normal operation in which the RO membrane of the reverse osmosis membrane device 4 is not sterilized will be described with reference to FIG. During this normal operation, the bypass valve 8 is closed.
When a water supply request is made to the water treatment system 1A (reverse osmosis membrane device 4), the control device 6A drives (operates) the raw water pump 2. Then, the raw water W1 containing an oxidizing agent is introduced into the activated carbon filtration device 7.

  In the activated carbon filtration device 7, the oxidizing agent contained in the raw water W1 is adsorbed and removed by the filter medium made of activated carbon. In addition, suspended substances, organic substances, chromaticity components, odor components and the like contained in the raw water W1 are also adsorbed and removed by the filter medium.

  Then, the raw water W1 from which the oxidizing agent has been removed is supplied to the reverse osmosis membrane device 4. Since the operation in the reverse osmosis membrane device 4 is the same as that in the case of the water treatment system 1 of the first embodiment, a duplicate description is omitted.

  Next, a control method for sterilizing the RO membrane of the reverse osmosis membrane device 4 will be described with reference to FIGS. 4 and 5. The point of sterilizing the RO membrane using the sterilizing action of the oxidizing agent contained in the raw water W1 is the same as in the case of the first embodiment.

  When the RO membrane is sterilized, as shown in FIG. 5, the RO membrane is performed in accordance with the flushing timing of the reverse osmosis membrane device 4. The control device 6A opens the closed bypass valve 8 at the time T2 when the flushing is started. Then, a part of the raw water W1 containing the oxidizing agent is introduced from the connection point J2 to the bypass line L4, flows through the bypass line L4, and joins the raw water line L1 at the connection point J3. The amount of the raw water W1 flowing through the bypass line L4 is arbitrarily set by adjusting the opening degree of the bypass valve 8.

  Further, the remaining raw water W1 containing the oxidant is introduced into the activated carbon filtration device 7 without flowing through the bypass line L4. The oxidizing agent contained in the raw water W1 is adsorbed and removed by the filter medium of the activated carbon filtration device 7.

  That is, when the bypass valve 8 is opened, the raw water W1 from which the oxidant has not been removed and the raw water W1 from which the oxidant has been removed are mixed and circulated in the raw water line L1 downstream of the connection point J3. . Therefore, raw water W1 containing an oxidizing agent is introduced into the reverse osmosis membrane device 4. The RO membrane of the reverse osmosis membrane device 4 is sterilized by the oxidizing action of the oxidizing agent contained in the raw water W1. Thereby, the propagation of various bacteria on the RO membrane is suppressed, and the formation of slime is suppressed. Then, when the flushing end time T3 is reached, the bypass valve 8 is closed and the sterilization of the RO membrane is ended.

According to the water treatment system 1A of the third embodiment described above, the following effects are exhibited.
The water treatment system 1A of the third embodiment includes an activated carbon filtration device 7 as an oxidant removing unit, a reverse osmosis membrane device 4, a bypass line L4, a bypass valve 8 and a control device 6A as an oxidant removing process control unit. And comprising.

  Therefore, when the RO membrane of the reverse osmosis membrane device 4 is sterilized, the control device 6A opens the bypass valve 8 of the bypass line L4 so that a part of the raw water W1 containing the oxidizing agent is passed to the activated carbon filtration device 7. Without being distributed, it can be supplied to the RO membrane. Thereby, propagation of miscellaneous bacteria on the RO membrane can be suppressed only when necessary by the oxidizing action of the oxidizing agent contained in the raw water W1. Therefore, it is possible to suppress the oxidative deterioration of the filtration membrane due to the oxidizing agent, it is possible to suppress the formation of slime, and the blockage of the RO membrane due to the slime can be suppressed.

  In the water treatment system 1A of the third embodiment, the control device 6A opens the bypass valve 8 during the flushing period. Therefore, the RO membrane can be sterilized using the period during which water supply is stopped. Therefore, when there is much water supply demand, water supply can be ensured.

[Fourth Embodiment]
The water treatment system of the fourth embodiment of the present invention has the same configuration as the water treatment system 1A of the third embodiment, but the water treatment system 1A of the third embodiment is controlled by the bypass valve 8. The method is different. Therefore, the control method of the bypass valve 8 in the fourth embodiment will be described with reference to FIG. 4 showing the water treatment system 1A of the third embodiment with reference to FIG. FIG. 6 is a time chart showing a method of controlling the bypass valve 8 according to the fourth embodiment of the present invention. FIG. 6 also shows the operating state of the reverse osmosis membrane device 4.

  In FIG. 6, symbols T1 to T4 indicate time. In the operation of the reverse osmosis membrane device 4, the time T1 to the time T3 are the same as the case shown in FIG. 2 of the first embodiment. In the operation of the bypass valve 8, time T1 and time T4 are times when the bypass valve 8 is closed. Time T2 is a time when the bypass valve 8 is opened.

  The control method during normal operation in which the RO membrane of the reverse osmosis membrane device 4 is not sterilized is the same as that in the case of the third embodiment, and thus redundant description is omitted.

When the RO membrane is sterilized, as shown in FIG. 6, the RO membrane is sterilized in accordance with the flushing timing of the reverse osmosis membrane device 4. The bypass valve 8 is closed until time T2 at which the execution of flushing is started.
The control device 6A opens the bypass valve 8 at the time T2 when the flushing start is started, and then continues this open state for a predetermined time until the time T4. Thereby, a part of raw | natural water W1 containing an oxidizing agent is introduce | transduced into the bypass line L4 from the connection point J2, flows through this bypass line L4, and merges with the raw | natural water line L1 in the connection point J3.

  And raw | natural water W1 containing an oxidizing agent is introduce | transduced into RO membrane as washing water at the time of implementation of flushing, and contacts the surface of the primary side of RO membrane. Therefore, the RO membrane is sterilized by the oxidizing action of the oxidizing agent contained in the raw water W1. Therefore, the propagation of various bacteria on the RO membrane is suppressed, and the formation of slime is suppressed.

  Further, the remaining raw water W1 containing the oxidant is introduced into the activated carbon filtration device 7 without flowing through the bypass line L4. The oxidizing agent contained in the raw water W1 is adsorbed and removed by the filter medium of the activated carbon filtration device 7. The bypass valve 8 is closed at time T4, but remains closed after time T3 when flushing is completed.

According to the water treatment system of 4th Embodiment demonstrated above, the effect shown below is show | played compared with the water treatment system 1A of the said 3rd Embodiment.
In the water treatment system of the fourth embodiment, the control device 6A opens the bypass valve 8 for a predetermined time (from time T2 to time T4) from the start of execution of flushing, and then closes the bypass valve 8.

  In the water treatment system 1A of the third embodiment, the bypass valve 8 is opened until time T3 when the flushing is finished. Therefore, a part of the raw water W1 containing the oxidizing agent is introduced into the reverse osmosis membrane device 4 via the bypass line L4. Therefore, the raw water W1 containing the oxidant remains in the vessel after time T3, and when the water supply standby time becomes longer than expected, the RO membrane may be deteriorated by the oxidizing action of the oxidant. is there.

  However, in the water treatment system of the fourth embodiment, as described above, the RO membrane is sterilized for a predetermined time by opening the bypass valve 8 from time T2 to time T4. Further, after time T4, the bypass valve 8 is closed, whereby the oxidizing agent is removed from the raw water W1 by the filter medium of the activated carbon filtration device 7. Therefore, the RO membrane is not exposed to the oxidizing agent. Therefore, even when the water supply standby time becomes long, it is possible to suppress the RO membrane from being deteriorated by the oxidizing action of the oxidizing agent.

[Fifth Embodiment]
Hereinafter, a water treatment system 1B according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a configuration diagram showing a water treatment system 1B according to a fifth embodiment of the present invention.
As shown in FIG. 7, in addition to the structure of the water treatment system 1 (refer FIG. 1) of the said 1st Embodiment, the water treatment system 1B of 5th Embodiment of this invention adds an oxidizing agent to raw | natural water W1. An oxidant addition device 10 is provided as an oxidant addition means. Moreover, the water treatment system 1B of 5th Embodiment is provided with the control apparatus 6B. Since the other structure of the water treatment system 1B is the same as the structure of the water treatment system 1 of the first embodiment, a duplicate description is omitted.

  As shown in FIG. 7, the oxidant addition device 10 is connected to an addition point J4 on the downstream side of the reducing agent addition device 3 in the raw water line L1. The addition point J4 is disposed upstream of the reverse osmosis membrane device 4. The position of the oxidizing agent addition point J4 is preferably downstream of the reducing agent addition point J1 and as close as possible to the addition point J1. This is due to the following reason.

  Downstream of the addition point J1, the oxidizing agent contained in the raw water W1 is removed by the reducing action of the reducing agent added from the addition point J1, and the sterilizing ability of the raw water W1 is removed. Therefore, it is necessary to suppress the propagation of various germs as much as possible on the downstream side of the addition point J1 in the raw water line L1.

The oxidant addition device 10 adds an oxidant to the raw water W1 flowing through the raw water line L1. The oxidant addition device 10 includes an oxidant storage unit 10a and an oxidant addition pump 10b.
The oxidant storage unit 10a stores an oxidant. As an oxidizing agent, sodium hypochlorite is mentioned, for example.

  The oxidant addition pump 10b sends the oxidant stored in the oxidant storage part 10a from the addition point J4 of the raw water line L1 to the raw water W1 and adds it. The oxidant addition pump 10b is electrically connected to a control device 6B (described later). Operation (drive and stop) of the oxidant addition pump 10b is controlled by a control device 6B (described later).

  The control device 6B has the same function as the control device 6 (see FIG. 1) of the water treatment system 1 of the first embodiment. The control device 6B is electrically connected to the oxidant addition pump 10b of the oxidant addition device 10. The control device 6B controls the operation (drive and stop) of the oxidant addition pump 10b.

Next, a control method for sterilizing the RO membrane of the reverse osmosis membrane device 4 will be described with reference to FIG. The point of sterilizing the RO membrane using the sterilizing action of the oxidizing agent contained in the raw water W1 is the same as in the case of the first embodiment.
However, as in the case of the first embodiment, simply using the sterilizing action of the oxidizing agent contained in the raw water W1 as it is may not provide sufficient sterilizing ability and the RO membrane may not be sufficiently sterilized.
Therefore, in the present embodiment, a predetermined amount of oxidant is added to the raw water W1 by the oxidant addition device 10 to enhance the sterilizing ability of the raw water W1.

  Specifically, the RO membrane is sterilized during the flushing period of the reverse osmosis membrane device 4 as in the case of the first embodiment. The control device 6B stops the operation of the reducing agent addition pump 3b and operates the oxidant addition pump 10b during the flushing period. By temporarily stopping the addition of the reducing agent (operation of the reducing agent addition pump 3b) to the raw water W1 containing the oxidizing agent, the oxidizing agent in the raw water W1 is not removed by the reduction treatment. Thereby, raw | natural water W1 with the oxidizing agent contained temporarily distribute | circulates the downstream of the addition point J1 in the raw | natural water line L1.

  Then, the control device 6B adds a predetermined amount of oxidant to the raw water W1 by the oxidant addition pump 10b of the oxidant addition device 10. Thereby, content of the oxidizing agent in raw | natural water W1 increases. Therefore, the sterilizing ability of the raw water W1 is enhanced. When the raw water W1 with enhanced sterilization capability is supplied to the RO membrane as cleaning water during the flushing and comes into contact with the primary surface of the RO membrane, the RO membrane oxidizes the oxidizing agent contained in the raw water W1. It is fully sterilized by the action. Therefore, the propagation of various bacteria on the RO membrane is suppressed, and the formation of slime is suppressed.

According to the water treatment system 1B of the fifth embodiment described above, the following effects are exhibited.
In addition to the configuration of the water treatment system 1 of the first embodiment, the water treatment system 1B of the fifth embodiment is an oxidation that adds an oxidant to an addition point J4 on the downstream side of the reducing agent addition device 3 in the raw water line L1. An agent addition device 10 is provided. Therefore, the content of the oxidizing agent in the raw water W1 can be increased by adding a predetermined amount of the oxidizing agent to the raw water W1 by the oxidizing agent adding device 10, and the sterilizing ability of the raw water W1 is strengthened only when necessary. Can do. Therefore, it is possible to suppress the oxidative deterioration of the filtration membrane due to the oxidizing agent, and it is possible to sufficiently sterilize the RO membrane only when necessary to suppress the propagation of various bacteria on the RO membrane, thereby suppressing the formation of slime. be able to.

[Sixth Embodiment]
Hereinafter, a water treatment system 1C according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a configuration diagram showing a water treatment system 1C according to a sixth embodiment of the present invention.
As shown in FIG. 6, the water treatment system 1 </ b> C of the sixth embodiment of the present invention is configured to add an oxidant by an oxidant addition device 10 at an addition point J <b> 5 inside the reverse osmosis membrane device 4. . For example, the addition point J5 is disposed on the downstream side of the pressurizing pump 4a and the upstream side of the RO membrane module 4b in the reverse osmosis membrane device 4.
Since the other configuration and control method of the water treatment system 1C are the same as the configuration and control method of the water treatment system 1B of the fifth embodiment, a duplicate description is omitted.

According to the water treatment system 1C of the sixth embodiment described above, the following effects are exhibited.
In addition to the configuration of the water treatment system 1 of the first embodiment, the water treatment system 1C of the sixth embodiment includes an oxidant addition device 10 that adds an oxidant to an addition point J5 inside the reverse osmosis membrane device 4. Prepare. Therefore, the content of the oxidizing agent in the raw water W1 can be increased by adding a predetermined amount of the oxidizing agent to the raw water W1 by the oxidizing agent adding device 10, and the sterilizing ability of the raw water W1 is strengthened only when necessary. Can do. Therefore, it is possible to suppress the oxidative deterioration of the filtration membrane due to the oxidizing agent, and it is possible to sufficiently sterilize the RO membrane only when necessary to suppress the propagation of various bacteria on the RO membrane, thereby suppressing the formation of slime. be able to.

As mentioned above, although one Embodiment of this invention was described, this invention is not restrict | limited to embodiment mentioned above, It can change suitably.
For example, in the first to sixth embodiments, the filtration membrane of the membrane separation means has been described as a reverse osmosis membrane (RO membrane), but is not limited thereto. For example, the filtration membrane may be an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane).

  Moreover, in the said 1st Embodiment and the said 2nd Embodiment, although demonstrated as what stops the addition of the reducing agent to the raw | natural water W1 in the implementation period of flushing, it is not restrict | limited to this. For example, the addition of the reducing agent to the raw water W1 may be stopped during the water supply.

  Moreover, in the said 6th Embodiment, although the addition point J5 of the oxidizing agent was demonstrated as what is located in the downstream of the pressurization pump 4a in the reverse osmosis membrane apparatus 4 and the upstream of the RO membrane module 4b, Not limited. For example, the addition point of the oxidizing agent may be upstream of the pressurizing pump 4 a in the reverse osmosis membrane device 4.

  Moreover, in the said 5th Embodiment and the said 6th Embodiment, although demonstrated as what adds an oxidizing agent to the raw | natural water W1 with the oxidizing agent addition apparatus 10, it is not restrict | limited to this. For example, water containing an oxidizing agent (for example, water containing residual chlorine) may be introduced from another system and added to the raw water W1. Further, water containing such an oxidizing agent may be introduced into the reverse osmosis membrane device 4 and circulated within the reverse osmosis membrane device 4.

1, 1A, 1B, 1C Water treatment system 3 Reducing agent addition device (oxidant removal means)
4 Reverse osmosis membrane device (membrane separation means)
6, 6A, 6B control device (oxidant removal processing control means)
7 Activated carbon filtration equipment (oxidizer removal means)
8 Bypass valve (Oxidant removal treatment control means)
10 Oxidizer addition device (Oxidant addition means)
W1 Raw water W2 Permeated water W3 Concentrated water L1 Raw water line L4 Bypass line (Oxidant removal treatment control means)

Claims (9)

A raw water line through which raw water containing an oxidizing agent circulates;
An oxidant removing means connected to the raw water line for removing the oxidant from the raw water;
A membrane separation means provided at the downstream end of the raw water line and separating the raw water into permeate and concentrated water by a filtration membrane;
An oxidant removal treatment control means for controlling the oxidant removal means so as to temporarily limit the treatment for removing the oxidant from the raw water when sterilizing the filtration membrane;
A water treatment system comprising. The oxidizing agent removing means is a reducing agent adding device for adding a reducing agent to raw water containing an oxidizing agent,
The water treatment system according to claim 1, wherein the oxidant removal processing control means is a reducing agent addition control device that temporarily stops the addition of the reducing agent to the raw water by the reducing agent addition device.   The said oxidizing agent removal process control means stops addition of the reducing agent to raw | natural water in the implementation period of the flushing which wash | cleans this filtration membrane by flowing raw | natural water on the surface of the primary side of the said filtration membrane. Water treatment system.   The said oxidizing agent removal process control means stops the addition of the reducing agent to the raw water for a predetermined time from the start of the execution of the flushing, and then adds the reducing agent to the raw water until the completion of the flushing. Water treatment system. The oxidant removing means is an activated carbon filtration apparatus that is provided in the raw water line and adsorbs and removes organic components and oxidants contained in the raw water by activated carbon.
The oxidant removal processing control means controls a bypass line connecting the upstream side and the downstream side of the activated carbon filtration device in the raw water line, a bypass valve for opening and closing the bypass line, and opening and closing of the bypass valve. The water treatment system of Claim 1 provided with a bypass valve control apparatus.   6. The water treatment system according to claim 5, wherein the oxidant removal treatment control means opens the bypass valve during a flushing period in which the filtration membrane is washed by flowing raw water on a primary surface of the filtration membrane. .   The water treatment system according to claim 6, wherein the oxidant removal processing control means opens the bypass valve for a predetermined time from the start of the flushing, and then closes the bypass valve until the end of the flushing.   The water treatment system according to any one of claims 1 to 7, further comprising an oxidant addition unit that adds an oxidant to the downstream side of the oxidant removal unit or the membrane separation unit in the raw water line.   The water treatment system according to any one of claims 1 to 8, wherein the filtration membrane is any one of a reverse osmosis membrane, an ultrafiltration membrane, and a microfiltration membrane.

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