JP4156984B2 - Cleaning method for separation membrane module - Google Patents

Description

洗浄工程の種類がＡ、排出比率が１．５と２のものは、上部・下部出入口への排出比率を、流量で変えた。また、Ｂの排出比率が１．５と２のものは、上部・下部出入口への排出比率を、流量を同じにして、下部出入口から排出する工程と上部出入口から排出する工程の排出時間の比率を変えた。
【００２６】
【発明の効果】
以上説明したように、本発明は、浄水用の原水ろ過用分離膜モジュールの洗浄方法（逆洗）として、簡便にしてかつ短時間で洗浄出来る有効な洗浄方法である。
【図面の簡単な説明】
【図１】図１は、本発明の実施の形態を示す、水ろ過装置の洗浄運転時の水のフローを示している。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cleaning a separation membrane module that obtains purified water by filtering natural water such as river water and groundwater, and various waste water, and more particularly to a method for cleaning a separation membrane module by backwashing.
[0002]
[Prior art]
In recent years, as a filtration facility for water purification, a method using a separation membrane module instead of a conventional coagulation sedimentation facility has been adopted because of facility cost and ease of operation.
[0003]
In general, when the filtration operation is continued using the separation membrane module, turbid components of raw water, free solids, or dissolved organic matter adhere to the membrane filtration surface, gradually reducing the membrane filtration capacity, and finally Membrane filtration becomes impossible. In order to prevent such a decrease in filtration capacity, generally, physical and manual removal work of film deposits is performed. Furthermore, this may be automated and mechanically removed physically for routine work. However, complete removal is difficult with physical cleaning, and strong physical cleaning tends to damage the membrane, shortening the lifetime of the membrane and necessitating replacement.
The replacement of the membrane leads to the suspension of the filtration operation and the permeate production. In order to prevent such a decrease in filtration capacity, a method of injecting a chemical solution, a method of back washing with a solution mixed with a bactericide, and the like have been proposed (JP-A-8-141375, JP-A-8-24857). ). Japanese Patent Laid-Open No. 2001-170456 proposes a method of periodically stopping filtration by mixing a chemical solution. However, both methods require considerable labor and time, and become a bottleneck for a water purification apparatus using a separation membrane.
[0004]
[Patent Document 1]
JP-A-8-141375
[0005]
[Patent Document 2]
JP-A-8-24857
[0006]
[Patent Document 3]
JP 2001-170456 A
[0007]
[Problems to be solved by the invention]
The present invention aims to solve the various problems as described above, and provides a method for cleaning a separation membrane that can be cleaned in a short time.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, the cleaning water is supplied from the permeation side of the separation membrane module having two inlets / outlets on the raw water side to the raw water side and discharged from the two inlets / outlets on the raw water side (A ′). The separation membrane module cleaning method for obtaining the permeated water by filtering the raw water, which makes a difference in the amount of the cleaning water discharged from the two inlets and outlets on the raw water side. In the step (A ′) of providing two inlets / outlets on the raw water side and supplying the wash water from the permeate side to the raw water side to wash the separation membrane, the amount of the wash water discharged from the two inlets / outlets is made different. is there. Deposits adhering to the separation membrane are generally easily separated by backwashing under a certain pressure in the direction perpendicular to the membrane, but this is not sufficient for strongly adhering deposits, and sometimes parallel to the membrane It is also necessary to apply the flow of As in the present invention, by making a difference in the amount of discharged water between the two outlets, a flow that extrudes deposits in a direction parallel to the membrane is generated, and peeling is facilitated.
[0009]
The invention of claim 2 of the present invention is the step (A) of supplying the wash water from the permeation side of the separation membrane module having an inlet / outlet on the raw water side to the raw water side and discharging it from the inlet / outlet on the raw water side; Is a method of cleaning the separation membrane module, comprising the step (C) of supplying a part of raw water to the outside of the system without allowing it to permeate to the permeate side. By discharging a part of the raw water out of the system without allowing it to permeate the permeate side, the dirt component on the raw water side can be removed from the system after cleaning, and the membrane cleaning effect can be enhanced.
[0010]
Further, the invention of claim 3 of the present invention has two inlets / outlets on the raw water side, and is discharged from the two inlets / outlets on the raw water side in the step (A ′) of discharging wash water from the two inlets / outlets on the raw water side. The amount of washing water can be made different.
[0011]
Further, according to the present invention, the step (A ′) includes a step of discharging the wash water from one of the two inlets / outlets on the raw water side and a step of discharging the wash water from the other inlet / outlet. be able to. At this time, the discharge amount may be made different by making a difference in the discharge time of the wash water discharged from the two entrances. By doing so, it is possible to create a flow of discharged water in parallel with the separation membrane and facilitate membrane peeling.
[0012]
Further, in the present invention, of the two inlets and outlets on the raw water side, discharge is performed such that the side with the larger discharge amount at the time of washing is the side with less raw water supply amount during normal raw water filtration or the side not supplying raw water. Can be made. In normal filtration, of course, it is considered that a larger amount of deposits are attached nearer to the inlet / outlet on the side opposite to the side where the raw water supply amount of the separation membrane module is larger. Therefore, the cleaning effect can be enhanced by supplying more cleaning water to the side where the supply amount is small.
[0013]
In the present invention, when the separation membrane module is installed upright in the length direction, the raw water is mostly supplied from the lower part, and the upper inlet / outlet becomes an outlet having a large discharge amount during cleaning.
[0014]
Furthermore, the separation membrane constituting the module of the present invention can be preferably a hollow fiber.
[0015]
Examples of the separation membrane include reverse osmosis membranes, nanofiltration membranes, ultrafiltration membranes and microfiltration membranes, and ultrafiltration membranes and microfiltration membranes are preferred. As the material of the separation membrane, cellulose acetate, cellulose, polyacrylonitrile, polysulfone, polyolefin, and the like can be used. Preferably, however, the cellulose resin, particularly cellulose acetate is further used because the backwashing effect appears remarkably. preferable.
[0016]
Furthermore, in this invention, a washing | cleaning liquid may contain 1-10 ppm of free chlorine components. By including a free chlorine component in the cleaning liquid, peeling of the adhered component from the film is promoted. In addition, it is not preferable that 10 ppm or more of free chlorine component is contained in the cleaning liquid from the viewpoint of the environmental impact caused by the waste liquid. Examples of the compound containing a free chlorine component include sodium hypochlorite.
[0017]
Furthermore, the present invention can include, in addition to the features of claims 1 and 2, a step (B) of stopping the operation for a predetermined time while holding the liquid in the separation membrane module. As a result, the deposits in the separation membrane are more easily detached. When the step (A) (or (A ′)) and the step (C) are used, these steps can be performed in the order of step (A) (or (A ′)) and then step (C). . Moreover, when using process (A) (or (A ')), (B), (C), those processes are performed in order of (A) (or (A')), (B), (C). be able to.
The ratio of the amount of washing water discharged from the two inlets and outlets on the raw water side in claims 1 and 3 can be selected according to the position where the separation membrane is heavily contaminated.
The operating conditions such as the flow rate of the cleaning liquid in the cleaning method of the separation membrane module of the present invention can be performed, for example, under the conditions described in the following examples.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a flow diagram of a water filtration device using a separation membrane module, showing an embodiment of the present invention, and arrows indicate the flow of cleaning water during a cleaning operation. In the separation membrane module targeted by the present invention, the washing water pumped by the pump from the permeate tank is discharged from the upper or lower inlet / outlet and used for washing the separation membrane module. By periodically cleaning the separation membrane module, the substance attached to the inner wall of the module membrane is cleaned and detached.
[0020]
The drainage at the time of washing was carried out by A) discharging separately into the upper entrance and the lower entrance, or B) exhausting the entire amount from the lower entrance first and then discharging the entire amount from the upper entrance.
[0021]
A small amount of sodium hypochlorite was mixed in the cleaning solution to contain a free chlorine component.
[0022]
【Example】
Using a FN20-FUC1582 (Daisen Membrane Systems Co., Ltd.) module having a membrane area of 16 m ² and a cellulose acetate hollow fiber membrane as a separation membrane module, river surface water was subjected to a filtration experiment. As a filtration process, the separation membrane module raw water was introduced from the lower inlet / outlet, and the concentrated water was discharged from the upper inlet / outlet. The discharge flow rate was 4 m ³ / hour. The filtration time was 30 minutes and the permeation flux was 6 m / day. As a washing process, a portion of the permeate was held in a tank and washed regularly. The washing flux was performed at 18 m / day, and the washing effluent was discharged A) separately at the upper inlet / outlet or the lower inlet / outlet, or B) first discharged to the lower inlet / outlet and then discharged from the upper inlet / outlet. The washing solution was mixed with sodium hypozinc acid of 3 to 5 ppm in terms of free chlorine. The total washing time was 1 minute. Next, in the operation stop process, the operation was stopped for 2 minutes while holding the cleaning liquid. In the washing liquid discharging step, 30% of the total amount was discharged out of the system while the raw water was introduced at 8 m ³ / hour from the lower inlet / outlet of the separation membrane module while the filtration was stopped. This process was performed for 2 minutes.
[0023]
[Comparative example]
The operation was performed in exactly the same manner as in the example except that the amount of discharge at the upper and lower outlets of the cleaning waste water was the same in the cleaning step, and the immersion step or the cleaning liquid discharging step was not performed.
[0024]
[Evaluation]
The transmembrane pressure converted to 25 ° C. at the start of the separation membrane module filtration step was compared with the transmembrane pressure converted to 25 ° C. after the operation was continued for 24 hours. Table 1 shows the operating conditions and the evaluation results. A cleaning method in which the increase in the transmembrane pressure after 24 hours of operation is low is an effective method.
[0025]
[Table 1]

When the cleaning process type was A and the discharge ratio was 1.5 and 2, the discharge ratio to the upper and lower entrances was changed by the flow rate. In addition, when the discharge ratio of B is 1.5 and 2, the ratio of the discharge time to the upper and lower doorways is the same as the flow rate, and the discharge time ratio of the process of discharging from the lower doorway and the process of discharging from the upper doorway Changed.
[0026]
【The invention's effect】
As described above, the present invention is an effective cleaning method that can be easily and quickly cleaned as a cleaning method (backwashing) of a separation membrane module for raw water filtration for water purification.
[Brief description of the drawings]
FIG. 1 shows a flow of water during a washing operation of a water filtration device according to an embodiment of the present invention.

Claims (9)

It consists of a process (A ') in which the wash water is supplied to the raw water side from the permeation side of the separation membrane module having two inlets and outlets on the raw water side, and discharged from the two inlets and outlets on the raw water side. A separation membrane module cleaning method for obtaining permeated water by filtering raw water, which makes a difference in the amount of discharged cleaning water ,
Of the two inlets and outlets on the raw water side, the inlet / outlet from which more washing water is discharged is an inlet / outlet that does not supply raw water or supplies a smaller amount of raw water at the time of raw water filtration. . It consists of a process (A ') in which the wash water is supplied to the raw water side from the permeation side of the separation membrane module having two inlets and outlets on the raw water side, and discharged from the two inlets and outlets on the raw water side. A separation membrane module cleaning method for obtaining permeated water by filtering raw water, which makes a difference in the amount of cleaning water discharged,
A method for cleaning a separation membrane module, wherein the separation membrane module is installed upright in the length direction, and an entrance through which more washing water is discharged is an upper entrance. The inlet / outlet through which more washing water is discharged out of the two inlets / outlets on the raw water side is an inlet / outlet that does not supply raw water or supplies a smaller amount of raw water during raw water filtration. Cleaning method for separation membrane module. The separation membrane according to any one of claims 1 to 3 , wherein the step (A ') comprises a step of discharging washing water from one of the two inlets / outlets on the raw water side and a step of discharging washing water from the other inlet / outlet. How to clean the module. The separation membrane module according to any one of claims 1 to 4, wherein the amount of the wash water discharged is differentiated by making a difference in the discharge time of the wash water discharged from the two inlets and outlets on the raw water side. Cleaning method for separation membrane module. The cleaning method according to any one of claims 1 to 5, further comprising a step (B) of stopping the cleaning operation for a predetermined time while holding the liquid in the module. The method for cleaning a separation membrane module according to any one of claims 1 to 6, wherein the separation membrane is a hollow fiber. The method for cleaning a separation membrane module according to any one of claims 1 to 7, wherein the separation membrane is made of a cellulose-based resin. The separation membrane module cleaning method according to any one of claims 1 to 8, wherein the cleaning water contains 1 to 10 ppm of a free chlorine component.

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