KR20110007180A - Method of operating reverse osmosis membrane module - Google Patents

Abstract

Not only deposits deposited on the surface of the reverse osmosis membrane, but also excellent microbial, organic, and inorganic substances strongly adsorbed on the membrane surface of the reverse osmosis membrane are obtained, the operation of the reverse osmosis membrane module capable of performing a sufficient amount of recovery It is an object of the present invention to provide a method, which alternates from normal operation of the reverse osmosis membrane module 3 so that a part of the permeate water of the reverse osmosis membrane module 3 is periodically or irregularly. We flow from brine side of water supply side to water supply side.

Description

Operation method of reverse osmosis membrane module {METHOD OF OPERATING REVERSE OSMOSIS MEMBRANE MODULE}

The present invention relates to a method of operating a reverse osmosis membrane module.

Since spiral reverse osmosis membranes (RO membranes) are effective for removing ions and organic matters from raw water, they are widely used in seawater desalination apparatuses, ultrapure water production apparatuses, and medical water purification apparatuses. For example, the RO membrane seals three sides by bonding or the like in a state where two membranes are polymerized in a state where a spacer of permeate is sandwiched between them, and the other side is connected to the water collecting pipe. And one or more membranes are connected to a collection pipe, and it wound up in the state which arrange | positioned the raw water spacer between the membranes, and is obtained as a cylindrical RO membrane module.

Raw water is supplied from one end face of the RO membrane module, discharged as concentrated water from the other end face while exiting the raw water spacer, and water leaving the RO membrane is obtained as permeate water.

In the case where insoluble substances such as turbidity and fine particles are mixed in the raw water to be treated in this way, or in a system where microorganisms are easy to grow, the cross section of the RO membrane is blocked by turbidity, fine particles, microorganisms or products by microorganisms, and the like. There was a problem that the quantity of was not obtained.

In such a case, it is necessary to perform the cleaning operation of the RO membrane module. DESCRIPTION OF RELATED ART Conventionally, as a washing | cleaning operation method of a RO membrane module, the method which removes the suspended matter which accumulate | stored in RO membrane by flowing raw water from a brine side to a RO membrane regularly or irregularly is disclosed (refer patent document 1, 2). ).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-141846

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-261724

However, in the method disclosed in Patent Documents 1 and 2, the cleaning effect is recognized with respect to deposits deposited on the surface of the RO membrane. However, the amount of the microorganism, organic matter, inorganic matter, etc. strongly adsorbed on the membrane surface has a small amount of flashing effect, and thus a sufficient quantity. There was a problem that could not be expected to recover.

Thus, in order to solve the above problems, the present invention obtains excellent cleaning effect not only on deposits deposited on the RO membrane surface, but also on microorganisms, organic substances, inorganic substances, etc. strongly adsorbed on the RO membrane surface, and performs sufficient quantity recovery. An object of the present invention is to provide a method of operating a reverse osmosis membrane module.

In order to solve the above problems, firstly, the present invention is a method of operating a reverse osmosis membrane module, characterized in that a part of the permeate of the reverse osmosis membrane is passed from the brine side of the reverse osmosis membrane to the water supply side regularly or irregularly. To provide (Invention 1).

According to the invention (Invention 1), by passing a part of the permeate of the reverse osmosis membrane from the brine side of the reverse osmosis membrane, it is possible to remove deposits such as turbidity deposited on the membrane surface of the reverse osmosis membrane and from the brine side of the reverse osmosis membrane. Since the water to be passed is high-purity water that is the permeate of the reverse osmosis membrane, microorganisms, organic substances, inorganic substances, and the like strongly adsorbed on the membrane surface can be removed more effectively, and a sufficient treatment water recovery effect can be exhibited.

In the said invention (Invention 1), it is preferable to add an oxidizing agent and / or a bactericide to the said permeate water (invention 2). According to this invention (invention 2), microorganisms, organic substances, and inorganic substances strongly adsorbed on the membrane surface of the reverse osmosis membrane can be removed more effectively by the action of an oxidizing agent or a bactericide, and further, a sufficient effect of recovering the amount of treated water is achieved.

In the said invention (invention 2), it is preferable that the said oxidizing agent is 1 type, or 2 or more types chosen from the group which consists of sodium hypochlorite, sodium hypobromite, hydrogen peroxide, ozone, and chloramine (invention 3).

In the said invention (invention 1-3), it is preferable to pass through the said permeated water which adjusted pH to 10 or more or 3 or more. According to this invention (invention 4), after adjusting the pH of permeate water to 10 or more or 3 and passing through from the brine side of the reverse osmosis membrane module, microorganisms, organic substances, inorganic substances, etc. strongly adsorbed to the membrane surface of the reverse osmosis membrane Can be removed more effectively, and moreover, a sufficient treatment water recovery effect is achieved. In particular, by adjusting the pH of the permeated water passing through the brine side of the reverse osmosis membrane to 10 or more, the effect of removing the organic matter firmly adhered to the membrane surface is improved, and the pH is adjusted to 3 or less to firmly adhere to the membrane surface. The effect of removing minerals is improved. Furthermore, by adjusting the pH of the permeate to 3 or less, the effect of the oxidant in the case where an oxidant is added to the permeate can be increased and the effect of removing microorganisms can be improved.

Secondly, the present invention provides a method of operating a reverse osmosis membrane module that periodically passes water from a brine side to a water supply side of a reverse osmosis membrane, wherein an oxidizing agent and / or a bactericide is added to the raw water. It provides a method of operating the permeable membrane module (invention 5).

According to the above invention (Invention 5), by adding at least an oxidizing agent and / or a bactericide to raw water supplied from the brine side of the reverse osmosis membrane, the turbidity and the like deposited on the membrane surface of the reverse osmosis membrane can be removed by the action of the oxidizing agent and / or the bactericide. At the same time, it is possible to effectively remove microorganisms, organic matter, inorganic matters and the like firmly adhered to the membrane surface.

In the said invention (invention 5), it is preferable that the said oxidizing agent is 1 type, or 2 or more types chosen from the group which consists of sodium hypochlorite, sodium hypobromite, hydrogen peroxide, ozone, and chloramine (invention 6).

In the said invention (invention 5, 6), it is preferable to pass through the said raw water which adjusted pH to 10 or more (invention 7). According to this invention (Invention 7), the pH of the raw water is adjusted to 10 or more, and then passed through the brine side of the reverse osmosis membrane module to more effectively remove microorganisms, organic substances, and inorganic substances adsorbed on the membrane surface of the reverse osmosis membrane. It is also possible to achieve a recovery effect of sufficient throughput. In particular, by adjusting the pH of the raw water passing through to the brine side of the reverse osmosis membrane to 10 or more, the effect of removing the organic matter firmly adhered to the membrane surface is improved, and the inorganic substance firmly adhered to the membrane surface by adjusting the pH to 3 or less. The effect of removing it is improved.

According to the present invention, not only the deposit deposited on the surface of the RO membrane but also an excellent cleaning effect can be obtained not only on microorganisms, organic substances, inorganic substances, etc. strongly adsorbed on the RO membrane surface, but also on the reverse osmosis membrane module capable of performing sufficient quantity recovery. It can provide a driving method of.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow diagram showing a reverse osmosis membrane device to which an operating method of a reverse osmosis membrane module according to a first embodiment of the present invention can be applied.
Fig. 2 is a flow diagram showing a reverse osmosis membrane device to which the operating method of the reverse osmosis membrane module according to the second embodiment of the present invention can be applied.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

1 is a flow diagram of a reverse osmosis membrane device to which a method for operating a reverse osmosis membrane module according to a first embodiment of the present invention can be applied, and FIG. 2 is a reverse osmosis membrane module according to a second embodiment of the present invention. It is a flow chart of the reverse osmosis membrane apparatus which can apply a driving method.

[First Embodiment]

As shown in Fig. 1, the reverse osmosis membrane apparatus 1 to which the operation method of the reverse osmosis membrane module according to the present embodiment can be applied includes a raw water tank 2 for storing raw water as water to be treated and a raw water tank. (2) added to the reverse osmosis membrane module (3) for separating raw water from the reverse osmosis membrane module (3), a backwash tank (4) for storing a part of the permeate water of the reverse osmosis membrane module (3), and a backwash tank (4) It is provided with a chemical tank (5) for storing the medicine.

The raw water tank 2 is connected to the reverse osmosis membrane module 3 through the first pump P1 and the raw water supply pipe 61, and the first open / close valve 71 is provided in the raw water supply pipe 61. It is installed. On the other hand, the turbidity and TOC concentration of the raw water stored in the raw water tank 2 is not particularly limited, but the water supply path of the reverse osmosis membrane module 3 is relatively high turbidity (for example, about 5 to 10 degrees) and TOC concentration. Even raw water (for example, about 10 to 1000 mg / L) can be treated without particular problem.

The reverse osmosis membrane module 3 is connected with a condensate discharge pipe 62 for discharging concentrated water and a permeate discharge pipe 63 for discharging permeate, and a condensate discharge pipe 62 and a permeate. The water discharge pipe 63 is provided with a second on-off valve 72 and a third on-off valve 73, respectively.

A permeate water intake pipe 64 is connected to an upstream side of the third open / close valve 73 in the permeate water discharge pipe 63, and through the permeate water intake pipe 64, the backwash water tank 4 ) Is connected. The fourth open / close valve 74 is provided in the permeate water intake pipe 64, whereby a part of the permeate is stored in the backwash tank 4.

The backwash tank 4 is connected to the upstream side of the second open / close valve 72 as the middle of the concentrated water discharge pipe 62 through the second pump P2 and the backwash water supply pipe 65. . In addition, a chemical tank 5 is connected to the backwash tank 4 via a third pump P3.

The chemical tank 5 stores a chemical added to the permeate stored in the backwash tank 4. Such chemicals include, for example, oxidizing agents such as sodium hypochlorite, sodium hypobromite, hydrogen peroxide (hydrogen peroxide), ozone, chloramine; Benzoisothiazolin-3-one, 2,2-dibromo-3-nitrilopropionamide (DBNPA), 2-2-dibromo-2-nitroethanol, bis-1,4-bromoacetki Fungicides such as 2-butene, 5-chloro-2-methyl-4-isothiazolin-3-one, glutaraldehyde, and quaternary ammonium salts; If it is a drug that can remove inorganic matters are not limited thereto.

Between the first opening / closing valve 71 and the reverse osmosis membrane module 3 in the raw water supply pipe 61, a backwash water discharge pipe 66 for discharging backwash water during backwashing is connected. The sixth on-off valve 76 is provided in the water discharge pipe 66.

In the reverse osmosis membrane device 1 having such a configuration, the first to third on-off valves 71 to 73 are opened and the fourth to sixth in normal operation (water collection operation) for collecting permeate. The on-off valves 74 to 76 are closed to operate the first pump P1. The raw water stored in the raw water tank 2 is supplied to the reverse osmosis membrane module 3 through the raw water supply pipe 61, and the permeate is discharged by the separation treatment in the reverse osmosis membrane module 3. At the same time, the concentrated water is discharged out of the system through the condensed water discharge pipe 62 through the condensed water discharge pipe 62.

The permeated water discharged out of the system through the permeate discharge pipe 63 is fed to a water treatment device (not shown) at the rear end, while the concentrated water discharged out of the system through the concentrated water discharge pipe 62 is It is supplied to a waste water treatment apparatus (not shown).

After performing the above-mentioned normal operation for a predetermined time, flashing is performed. Such flashing may be performed regularly or may be performed irregularly. The interval between alternating normal operation and flashing is not particularly limited, and may be alternated every predetermined time (e.g., 1 to 100 hours), and alternates at a time when a predetermined hydraulic pressure difference (e.g., about 0.1 to 1 MPa) is reached. You may make it alternate, and you may make it alternate when the fall rate of permeate amount becomes predetermined value (for example, 5 to 20%).

Prior to the flashing, the fourth on-off valve 74 is opened while the above-described normal operation is performed, and the backwash permeate is stored in the backwash tank 4.

When a predetermined amount of permeated water is stored in the backwash tank 4, the third pump P3 is operated so that the chemical is backwashed from the chemical tank 5 so that the concentration of the chemicals (oxidizers, sterilizers, etc.) of the permeated water is a predetermined concentration. Is added to the tank 4. On the other hand, the oxidizing agent concentration or the sterilizing agent concentration of the permeated water can be appropriately set depending on the blockage of the membrane surface of the reverse osmosis membrane module 3 as long as the desired cleaning effect is obtained and the concentration of the reverse osmosis membrane is not degraded. For example, when using sodium hypochlorite or sodium hypobromite as an oxidizing agent, it is preferable to add so that these concentrations may be 0.01-1 mg / L, and when using hydrogen peroxide as an oxidizing agent, the concentration may be 10-10000 mg / L. It is preferable to add as much as possible. In addition, when using benzoisothiazolin-3-one as a fungicide, what is necessary is just to add so that the density | concentration may be 0.001-10 mg / L.

Then, the first to third on / off valves 71 to 73 are closed, and the fifth on / off valve 75 and the sixth on / off valve 76 are opened to operate the second pump P2. . As a result, backwashing water (permeated water to which a chemical (oxidizing agent, sterilizing agent, etc.) is added) is supplied to the upstream side of the second opening / closing valve 72 in the concentrated water discharge pipe 62. On the other hand, the fourth open / close valve 74 may be in an open state or in a closed state. However, the fourth open / close valve 74 may be in a closed state, because the fourth open / close valve 74 is preferable because of its excellent removal effect such as suspended matter deposited on the membrane surface of the reverse osmosis membrane.

The backwash water supplied to the upstream side of the second open / close valve 72 of the concentrated water discharge pipe 62 is the closed / close water discharge side of the reverse osmosis membrane module 3 because the second open / close valve 72 is closed. It is passed to (Brine side).

The amount of water to the reverse osmosis membrane module 3 can be appropriately determined depending on the blocking state of the membrane surface of the reverse osmosis membrane. However, in the 4-inch module, for example, at least 300 L / hr or more per piece is preferably 600 L / hr or more. More preferred. In addition, in an 8-inch module, it is preferable that it is at least 2 m ³ / hr or more, and more preferably ³ m ³ / hr or more. In addition, it is preferable that the feed water pressure of the backwash water to the concentrated water discharge side of the reverse osmosis membrane module 3 is 0.1 to 2 MPa.

 In this way, the backwash water is passed through to the concentrated water discharge side of the reverse osmosis membrane module 3, so that the turbidity and the like deposited on the membrane surface can be effectively removed, and the backwash water passed through the concentrated water discharge side of the reverse osmosis membrane module 3 is obtained. By containing chemicals (oxidizing agents, fungicides, etc.), microorganisms, organic substances, inorganic substances, etc. firmly adhered to the membrane surface can be dissolved and removed by the action of these chemicals.

The backwash water passed to the concentrated water discharge side of the reverse osmosis membrane module 3 is discharged from the water supply side. At this time, since the first opening / closing valve 71 is closed and the sixth opening / closing valve 76 is open, the backwash water is discharged out of the system through the backwash water discharge pipe 66. The backwash water discharged out of the system may be discharged after a predetermined treatment, or may be supplied back to the raw water tank 2 in view of the water recovery rate.

When the flashing of the reverse osmosis membrane module 3 is completed in this manner, the first to third open / close valves 71 to 73 are opened, and the fourth to six open / close valves 74 to 76 are closed. It is good to change to normal operation.

As described above, according to the operating method of the reverse osmosis membrane module 3 according to the first embodiment, not only the deposit deposited on the surface of the reverse osmosis membrane, but also microorganisms, organic substances, and inorganic substances firmly adhered to the reverse osmosis membrane surface. Excellent flashing effect can also be obtained, and the like, and the amount of permeated water can be sufficiently recovered.

In particular, in the first embodiment, the reverse osmosis membrane permeate is used as the backwash water passing through to the concentrated water discharge side of the reverse osmosis membrane module 3, so that the chemicals (oxidizing agents, sterilizers, etc.) added to the permeate water before flashing. Since it is not consumed, water can be passed to the concentrated water discharge side of the reverse osmosis membrane module 3 while maintaining the flashing effect of these chemicals, and a better flashing effect can be obtained, and the amount of permeate can be sufficiently recovered. .

Second Embodiment

Next, 2nd Embodiment of this invention is described based on drawing.

As shown in Fig. 2, the reverse osmosis membrane apparatus 10 to which the operation method of the reverse osmosis membrane module according to the second embodiment can be applied includes: a raw water tank 12 for storing raw water as water to be treated; A reverse osmosis membrane module 13 for separating raw water from the water tank 2 and a chemical tank 15 for storing chemicals are provided.

The raw water tank 12 is connected to the reverse osmosis membrane module 3 through the first pump P11 and the raw water supply pipe 161, and the first open / close valve 171 is provided on the raw water supply pipe 161. It is installed.

The reverse osmosis membrane module 13 is connected to the concentrated water discharge pipe 162 for discharging the concentrated water and the permeate discharge pipe 163 for discharging the permeate, and the concentrated water discharge pipe 162 and the permeation. The water discharge pipe 163 is provided with a second open / close valve 172 and a third open / close valve 173, respectively.

A raw water branch pipe 164 for supplying raw water as backwash water is connected to an upstream side of the first on-off valve 171 in the raw water supply pipe 161, and the raw water branch pipe 164 is used for discharging concentrated water. It is connected to the upstream side of the 2nd switching valve 172 in the piping 162. As shown in FIG. In addition, a fourth open / close valve 174 and a fifth open / close valve 175 are installed in the raw water branch pipe 164, and a second pump is provided between the fourth open / close valve 174 and the fifth open / close valve 175. The chemical tank 15 is connected through P112.

The chemical tank 15 stores chemicals for adding to the raw water supplied through the raw water branch pipe 164. As such a chemical | medical agent, the thing similar to the chemical | medical agent stored in the chemical | medical agent tank 5 in 1st Embodiment mentioned above may be used.

On the downstream side of the first opening / closing valve 171 in the raw water supply pipe 161, a backwash water discharge pipe 166 for discharging backwash water during backwashing is connected, and a backwash water discharge pipe 166 is connected to the backwash water discharge pipe 166. The sixth on-off valve 176 is provided.

In the reverse osmosis membrane device 10 having such a configuration, the first to third opening / closing valves 171 to 173 are opened and the fourth to six opening and closing operations are performed during normal operation (water collection operation) for collecting permeate. With the valves 174 to 176 closed, the first pump P11 is operated. The raw water stored in the raw water tank 12 is supplied to the reverse osmosis membrane module 13 through the raw water supply pipe 161, and the permeate is discharged by the separation treatment in the reverse osmosis membrane module 13. The concentrated water is discharged out of the system through the pipe 163 and the concentrated water is discharged out of the system through the concentrated water discharge pipe 162.

The permeated water discharged out of the system through the permeate discharge pipe 163 is supplied to a water treatment device (not shown) at the rear end, while the concentrated water discharged out of the system through the concentrated water discharge pipe 162 is connected to the rear end. It is supplied to a waste water treatment apparatus (not shown).

Flashing is performed after the normal operation as described above is performed for a predetermined time. Normal operation and flashing may be alternated regularly or irregularly. In addition, what is necessary is just to make the space | interval which alternates such operation | movement the same as 1st Embodiment mentioned above.

When flashing is performed, firstly, the fourth to six on / off valves 174 to 176 are opened in a state where the first pump P11 is operated, and the first on / off valve 171 and the second on / off valve ( 172) to the closed state. Accordingly, the raw water is supplied from the raw water tank 12 to the upstream side of the second on / off valve 172 of the concentrated water discharge pipe 162 through the raw water branch pipe 164. On the other hand, the third open / close valve 173 may be in an open state or in a closed state. However, the third open / close valve 173 is preferable because the third open / close valve 173 is excellent in the removal effect such as the suspended matter deposited on the membrane surface of the reverse osmosis membrane.

At this time, the second pump P12 is operated to add chemicals (oxidizers, sterilizers, etc.) to the raw water in the raw water branch pipe 164 so that the chemical concentration of the raw water is a predetermined concentration. On the other hand, the chemical concentration of the raw water may be the same as in the first embodiment described above.

Since the second open / close valve 172 is closed, the backwash water (raw water to which chemicals (oxidizers, sterilizers, etc.) are added) supplied to the upstream side of the second open / close valve 72 of the concentrated water discharge pipe 162 is closed. , To the concentrated water discharge side (brine side) of the reverse osmosis membrane module 13. In addition, the amount of water passed to the reverse osmosis membrane module 3 and the water supply pressure may be the same as in the first embodiment described above.

In this way, the backwashing water (raw water to which chemicals (oxidizing agents, sterilizers, etc.) are added) is passed through the concentrated water discharge side of the reverse osmosis membrane module 13, so that the turbidity and the like deposited on the membrane surface can be effectively removed. In addition, since the backwash water passed to the concentrated water discharge side of the reverse osmosis membrane module 13 contains a chemical (oxidizing agent, bactericide, etc.), microorganisms, organic substances, inorganic substances, etc. strongly adhered to the membrane surface by such chemical action. It can also melt | dissolve and remove.

The backwash water passed to the concentrated water discharge side of the reverse osmosis membrane module 13 is discharged from the water supply side. At this time, since the first on-off valve 171 is in the closed state and the sixth on-off valve 176 is in the open state, the backwash water is discharged to the outside of the system through the backwash water discharge pipe 166. The backwash water discharged out of the system may be discharged after performing a predetermined treatment, or may be supplied back to the raw water tank 12 in view of the water recovery rate.

When the flashing of the reverse osmosis membrane module 13 is completed in this manner, the first to third open / close valves 171 to 173 are opened and the fourth to six open / close valves 174 to 176 are closed. You can shift by driving.

As described above, according to the operating method of the reverse osmosis membrane module 13 according to the second embodiment, not only deposits deposited on the surface of the reverse osmosis membrane, but also microorganisms, organic substances, and inorganic substances firmly adhered to the reverse osmosis membrane surface Excellent flashing effect can also be obtained, and the amount of permeated water can be sufficiently recovered.

[Other Embodiments]

In the first embodiment or the second embodiment, the oxidizing agent, the disinfectant, and the like are stored in the chemical tanks 5 and 15, and after the chemical is added to the backwashing water (permeate or raw water), the backwashing water is Although the reverse osmosis membrane modules (3) and (13) pass through the backwash water supply pipes (65) and (164) to the concentrated water discharge side, the chemical tanks (5) and (15) are not limited thereto. The pH adjuster, such as sodium hydroxide, potassium hydroxide, sulfuric acid, and hydrochloric acid, may be stored, and the pH adjuster may be added to the backwashing water.

The pH adjuster is added to the backwashing water, the pH of the backwashing water is adjusted to 10 or more or less than 3, preferably 10.5 to 12.5 or 1 to 2, and the backwashing water having adjusted the pH is reverse osmosis membrane module 3 The water may be passed to the concentrated water discharge side of (13). As a result, the deposited turbidity and the like on the surface of the reverse osmosis membrane can be removed, and microorganisms, organic substances, inorganic substances, and the like firmly adhered to the membrane surface of the reverse osmosis membrane can be effectively removed.

In this case, it is preferable to install a pH meter in the backwash tank 4 or the raw water branch pipe 164, and from the chemical tanks 5, 15, the backwash tank 4 is based on the signal from the pH meter. Alternatively, the addition amount of the pH regulator to the raw water branch pipe 164 may be controlled.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the said embodiment is intended to include all the design changes and equivalents which belong to the technical scope of this invention.

In the above embodiment, flashing is performed using a backwashing water containing a chemical (oxidizing agent, bactericide, etc.) or a pH adjuster, but the pH of the backwashing water is set to 3 or more by adding a pH adjusting agent together with a chemical (oxidizing agent, bactericide, etc.). You may adjust to 10 or more. By adjusting the pH to 3 or more, it is possible to improve the oxidizing power of the oxidizing agent contained in the backwash water, and to effectively remove microorganisms and the like firmly adhered to the membrane surface of the reverse osmosis membrane, even if the inorganic substance is present on the membrane surface. You can remove it. Moreover, by adjusting pH to 10 or more, the effect which peels, melt | dissolves, and removes the organic substance adhering to the membrane surface according to chemicals can be improved more.

Further, in the first embodiment, flashing is performed using backwashed water to which chemicals (oxidizing agents, bactericides, etc.) are added, but the present invention is not limited thereto. Also good.

Example

Hereinafter, although an Example and a comparative example are illustrated and this invention is demonstrated in detail, this invention is not limited to the following Example.

Example 1

Using the reverse osmosis membrane apparatus 1 having the flow shown in FIG. 1, organic wastewater treated (turbidity: 2 degrees, conductivity: 80 mS / m, TOC concentration: 2 µg / mL) was supplied with a water supply pressure of 0.7 MPa and water supply. Water flowed for 1000 hours at a flow rate of 20 L / min. Thereafter, the permeate was passed from the brine side once every four hours for 10 minutes while storing the permeate from the reverse osmosis membrane module 3 in a suitable backwash tank 4. The amount of water passed from the brine side was 20 L / min, and the water supply pressure was 0.3 MPa. Then, the water permeation amount (m ³ / d) after 10 hours and 2000 hours after the start of water passage was measured, and the permeation amount decrease rate (%) was calculated from these measured values. On the other hand, as the reverse osmosis membrane module 3, a 4 inch reverse osmosis membrane (ES20-D4) manufactured by Nitto Denko Co., Ltd. was used.

The results are shown in Table 1.

[Example 2]

Permeate water in the same manner as in Example 1 except that sodium hypochlorite was added to the permeated water stored in the backwash tank 4 so as to have a concentration of 0.05 mg / L. (m ³ / d) was measured, and the permeation amount reduction rate (%) was calculated from these measured values.

The results are added to Table 1 and shown.

Example 3

Permeate water was passed in the same manner as in Example 1 except that hydrogen peroxide water was added to the permeated water stored in the backwash tank 4 so that the concentration of hydrogen peroxide was 100 mg / L. (m ³ / d) was measured, and the permeation amount reduction rate (%) was calculated from these measured values.

The results are added to Table 1 and shown.

Example 4

Permeate water in the same manner as in Example 1 except that NaOH was added so that the pH of the permeated water stored in the backwash tank 4 was 12, and the amount of permeated water after 10 hours and 2000 hours after the start of water passage (m ³ / d ) Was measured, and the permeation amount reduction rate (%) was calculated from these measured values.

The results are added to Table 1 and shown.

Example 5

Using the reverse osmosis membrane apparatus 10 having the flow shown in FIG. 2, organic wastewater treated (turbidity: 2 degrees, conductivity: 80 mS / m, TOC concentration: 2 µg / mL) was supplied with a water supply pressure of 0.75 MPa and a water supply. Water flowed for 1000 hours at a flow rate of 20 L / min. Thereafter, once every four hours for 10 minutes, the raw water was passed from the brine side, and an isothiazoline-based slime control agent was added to the raw water so that the concentration of bactericide was 1 µg / mL. The amount of water passed from the brine side was 20 L / min, and the water supply pressure was 0.3 MPa. Then, the water permeation amount (m ³ / d) after 10 hours and 2000 hours after the start of water passage was measured, and the permeation amount decrease rate (%) was calculated from these measured values. On the other hand, as the reverse osmosis membrane module 3, a 4 inch reverse osmosis membrane (ES20-D4) manufactured by Nitto Denko Co., Ltd. was used.

The results are added to Table 1 and shown.

Comparative Example 1

Water was added in the same manner as in Example 5 without adding anything to the raw water, and the water permeation amount (m ³ / d) after 10 hours and 2000 hours after the start of water passage was measured, and the permeation amount decrease rate (%) was calculated from these measurements. .

The results are added to Table 1 and shown.

Permeate amount (m ³ / d)
% Degradation 10 hours later After 2000 hours Example 1 6.5 5.9 90.8 Example 2 6.5 6.3 96.9 Example 3 6.5 6.2 93.9 Example 4 6.5 6.2 95.4 Example 5 6.5 6.0 92.3 Comparative Example 1 6.6 5.2 78.8

As shown in Table 1, the method of Example 1 in which the permeated water of the reverse osmosis membrane was passed from the brine side of the reverse osmosis membrane to the water supply side was compared with that of Comparative Example 1 in which raw water was passed from the brine side of the reverse osmosis membrane to the water supply side. It was confirmed that the decrease in the amount of permeated water of the permeation membrane can be suppressed and the operation can be stably performed for a long time. In addition, as in Examples 2 to 4, an oxidizing agent is added to the permeate or the pH of the permeate is adjusted to 10 or more, and then the permeate is passed from the brine side of the reverse osmosis membrane, whereby the amount of permeated water of the reverse osmosis membrane is lowered. It was confirmed that can be suppressed more. Furthermore, as in Example 5, it was confirmed that the raw water to which the fungicide was added was passed from the brine side of the reverse osmosis membrane to suppress the decrease in the amount of permeated water of the reverse osmosis membrane and to operate stably for a long time.

The operating method of the reverse osmosis membrane module of the present invention is high turbidity that is likely to cause blockage on the membrane surface, and is useful for treatment of raw water containing a high concentration of TOC.

1,10... Reverse osmosis membrane device
2,12... Water tank
3,13... Reverse osmosis membrane module
4… Backwash tank
5,15... Chemical tank

Claims (7)

And a portion of the permeated water of the reverse osmosis membrane is periodically or irregularly passed from the brine side of the reverse osmosis membrane to the water supply side. The method according to claim 1,
Operating method of the reverse osmosis membrane module characterized in that the oxidizing agent and / or sterilizing agent is added to the permeate. The method according to claim 2,
And the oxidant is one or two or more selected from the group consisting of sodium hypochlorite, sodium hypobromite, hydrogen peroxide, ozone and chloramine. The method according to any one of claims 1 to 3,
A method of operating a reverse osmosis membrane module, characterized in that water is passed through the permeated water adjusted to a pH of 10 or 3 or more. As an operation method of the reverse osmosis membrane module which passes raw water from the brine side of the reverse osmosis membrane to the water supply side regularly or irregularly,
Operating method of the reverse osmosis membrane module characterized in that the oxidizing agent and / or sterilizing agent is added to the raw water. The method according to claim 5,
And the oxidant is one or two or more selected from the group consisting of sodium hypochlorite, sodium hypobromite, hydrogen peroxide, ozone and chloramine. The method according to claim 5 or 6,
Operating method of the reverse osmosis membrane module characterized in that the water is adjusted to adjust the pH to 10 or more.

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