JPS6178403A - Method for washing membrane in membrane separation apparatus - Google Patents

Abstract

PURPOSE:To enhance washing effect and to enable the repeated use of a chemical solution while inexpensively performing the washing of a membrane with good efficiency, by contacting the chemical solution with the membrane in a state divided into plural times and reusing the chemical solution used in washing on and after a second stage without treating the same. CONSTITUTION:(n) Chemical solution tanks 11-13 are provided in order to wash a membrane in a multistage fashion. At first, an all amount of the chemical solution such as a NaOH solution of the chemical solution tank 11 is supplied to a washing tank 3. The chemical solution is sent to the concn. chamber 1a of a membrane separation apparatus 1 through piping 5 and returned to the washing tank 3 through piping 40. The solution transmitted through the membrane 2 is guided to an activated carbon filter tower 6 through pipings 50, 50a and purified to be introduced into a recovery chemical solution tank 21 from piping 51. After first stage washing, air is passed through the pipings 5, 40 to send the contents therein to the washing tank 3 and subsequently withdrawn to a concentrate tank. In second stage washing, the chemical solution of the chemical solution tank 12 is transferred to the washing tank 3 and sent to the concn. chamber 1a before returned to the washing tank 3. The solution transmitted through the membrane 2 is introduced into the recovery chemical solution tank 22 from pipings 50, 52. This operation is successively repeated.

Description

[Detailed description of the invention] [Industrial use! 7] Is the present invention extramembranous M? The present invention relates to a method of cleaning a membrane at t1, and in particular, to a method of cleaning an ultra-cancer membrane or a precision membrane contaminated with organic matter in multiple stages using a chemical solution.

[Prior Art] Membrane separation devices such as ultra-e peracid or EI!! filtration are well known as devices for saponification of liquids containing organic matter.
0 analogy If used in various industrial fields, JP-A-5
No. 8-198299 discloses that a saccharified solution obtained by atomizing cellulose with an enzyme is treated with an ultrafiltration membrane to produce a concentrated solution containing enzymes and undecomposed cellulose, and a permeated solution containing the produced sugar solution. A usage method for separating the two is disclosed.

However, in the IIL2 separation device, the collecting surface becomes contaminated with organic matter and the like as the device operating time passes, and the amount of permeate that passes through the membrane decreases. For this reason, I try to clean it, for example, once a day.

To clean such a membrane, an acid, an alkaline agent, or a solution of hypo-11ite (in this specification, a solution of such a cleaning chemical is referred to as a chemical solution) is used. In such a cleaning method using a chemical solution, a required amount of the chemical solution is brought into contact with the device at one time in - times of cleaning.

[Problem to be Solved by the Invention 1] However, in such a cleaning method, the cleaning effect is not necessarily sufficient, and the recovery rate of the amount of permeated liquid is not necessarily high. Furthermore, since the amount of cleaning waste generated as a result of cleaning is large, it is difficult to purify and reuse it. Therefore, the chemical solution was disposed of after being neutralized, resulting in a lot of wasted chemical solution.

[Means for Solving the Problems] In order to solve the above problems, the inventors have conducted intensive research and found that instead of bringing the chemical solution necessary for cleaning into contact with the membrane at once, the chemical solution is brought into contact with the membrane in two or more steps. It was found that the amount of permeate was more significantly recovered by dividing the membrane and bringing the divided amounts of chemical solution into contact with the membrane in order. Furthermore, most of the organic substances, particularly coloring components, attached to the membrane are removed during the first stage of cleaning, and therefore the chemical solutions used in the second and subsequent stages of cleaning are hardly contaminated and remain intact or It was also confirmed that it could be reused after replenishing a small amount of chemical solution.

The present invention has been made based on this knowledge, and involves dividing an ultrafiltration membrane or a precision filtration membrane contaminated with organic matter into n stages (n is a natural number of 2 or more) using a chemical solution to form multiple stages. In the cleaning method, n chemical liquid tanks and a chemical liquid cleaning device are provided.

■ After performing the first stage of cleaning, in which the membrane is cleaned with the chemical stored in the first chemical tank.

False The second and subsequent stages of cleaning are performed at least once, in which the membrane is cleaned using a chemical solution stored in a chemical solution tank different from the one used for the previous stage of cleaning.

The membrane permeate liquid in the first stage of cleaning passes through the chemical cleaning device, and the membrane permeable liquid in the second and subsequent stages of cleaning is returned to one of the chemical tanks without passing through the chemical cleaning device, and The gist of the present invention is a method for cleaning a membrane in an extra-membrane cleaning device, characterized in that the chemical liquid returned to each chemical tank is stored for use in the next cleaning.

The present invention will be explained in more detail below.

Examples of cleaning chemicals used in the present invention include alkaline agents, sodium hypochlorite, and surfactants. Among these, alkaline agents are generally preferred and can be used alone. Na as an alkaline agent
OH is most preferred.

Sodium hypochlorite is used in the final step of cleaning to sterilize the inside of the membrane separation device.

Therefore, it is preferable to use this sodium hypochlorite together with an alkaline agent in the last step.

In addition, a surfactant may be used in any of the cleaning steps (excluding the final cleaning if sodium hypochlorite is used for sterilization in the final step). One or a combination of any anionic surfactant, nonionic surfactant, zwitterionic surfactant or cationic surfactant known per se can be used.

If desired, known cleaning aids such as sodium sulfate, sodium charcoal, food 112, etc. can be added to the chemical solution used in the present invention for the purpose of further increasing cleaning power.

In the present invention, the cleaning temperature, that is, the temperature at the time of contact between the chemical solution and the membrane, is generally desirably in the range of 0 to 50 degrees Celsius, particularly 20 to 40 degrees Celsius, and the cleaning effect is insufficient at temperatures lower than 0 degrees Celsius. Furthermore, at temperatures higher than 50°C, film deterioration may occur, and W! Parts of the device incorporating 4, such as a supercer, may deteriorate.

Further, by washing the membrane with water or hot water before the first stage of washing, contaminants can be washed away and the cleaning efficiency can be improved. Furthermore, after the nth stage of cleaning, it is preferable to wash away the chemicals by washing with water or hot water.

In the present invention, the ultrafiltration membrane or the J# tight passage membrane may be made of the following materials. That is, the ultrafiltration membrane may be a collodion membrane supported on a porous substrate, a formaldehyde hardened gelatin 11Q, a cellophane membrane, a cellulose membrane, a cellulose acetate membrane, a polyethylene membrane, a polypropylene membrane, an acetyl cellulose, or a 1j0 bilayer membrane. Mixtures, polyacrylonitrile, polysulfone, sulfonated-2゜6-dimethylborifuenylene oxide, polyion complex, polyvinyl alcohol, polyvinyl chloride, etc., and as precision membranes, triacetate cellulose, nylon, polyvinyl chloride, etc. Various known materials such as , boso, and vinylidene chloride can be used.

The chemical cleaning device may be any device that can remove impurities from the chemical, such as an adsorption device using an adsorbent such as activated carbon or synthetic adsorbent, a reverse osmosis membrane with a low salt removal rate, or an ultrafiltration II. ! A membrane separation device such as No. 2 can be used.

FIG. 1 is an equipment and system diagram for implementing a preferred embodiment of the present invention.

1 is a 9-membrane separator, which has 11 ultrafiltration membranes or 2 membranes, and has a concentration chamber 1a and a permeation chamber 1b. Reference numeral 3 denotes a cleaning tank for supplying a cleaning chemical solution to the membrane external division device 1, which is communicated with the concentration chamber 1a of the component m device 1 through a conduit 5 having a pump 4. 6 is an activated carbon adsorption tower for cleaning the permeate taken out from the permeation chamber 1b. In addition, 7 is steam for heating the chemical liquid described later (note that a heater may be provided in place of this steam), and 8 is steam for heating the chemical liquid (in this embodiment, NaOH or NaC
9 is a valve for feeding air into the pipe 5.

Therefore, in Kihatsu IgJ, in order to wash the membrane 2 in multiple stages, n (in this embodiment, three) chemical baths 11 are used.
．． 12.13 shall be provided. Further, in this embodiment, recovery chemical liquid tanks 21, 22, and 23 are provided for temporarily storing the liquid that has passed through the membrane 2 of the membrane separation device.

Chemical liquid tanks 11 to 13 are connected to piping 30 and short pipes 31 to 3, respectively.
The liquid can be supplied to the cleaning tank 3 via 3.

A pipe 40 is connected to the liquid outlet side of the concentration chamber 1a of the membrane-separated ml, and the permeated liquid passes through this pipe 40 and is returned to the washing 4e3. In addition, the chemical solution can be returned to the chemical tanks 11 to 13 through a pipe 40a branched from the pipe 40. In the figure, 41, 42, and 43 indicate the pipes 40a, respectively.
This is an 'E1 pipe that connects the chemical liquid tank 11-13.

The permeation chamber 1b of the outer membrane N1 is connected to pipes 50 and 51 to 53.
It is connected to the recovered chemical liquid tanks 21 to 23 via. A pipe 50 a is branched from the middle of the pipe 50 and connected to the activated carbon filtering tower 6 , and the pipe 51 guides the liquid passing through the activated carbon filtering membrane 6 to the recovery chemical tank 21 .
The recovered chemical liquid tanks 21 to 23 have short pipes 61, 62, and 63, respectively.
and is connected to the middle of the pipe 40 via a pipe 60.

In the figure, 59 is a pump interposed in the middle of the piping 60.

70 is a pipe that communicates the bottom of the cleaning tank 3 and the pipe 40a.

Although not shown, each pipe is provided with a valve at an appropriate location to open and close the flow path.

Next, the operation of the system shown in FIG. 1 will be explained.

(1) Component # After operating the device 1 for a predetermined period of time, or when the amount of liquid permeated through the membrane 2 becomes lower than a predetermined value, the articulant separation device 2! The operation at t1 is stopped and the wave path is switched so that cleaning liquid, water, or hot water can be supplied to the membrane separator 1.

(2) Preferably, first, warm water is supplied to the concentration chamber 1a of 7 liters of membrane outer enclosure to clean the inside of the device 1. This cleaning waste liquid is disposed of after being subjected to appropriate treatment (note that hot water piping is not shown in Figure fS1).

(3) The NaOH solution stored in the chemical solution tank 11 is supplied to the entire cleaning tank 3.

(4) Na in the cleaning tank 3 is placed in the concentration chamber 1a of the membrane separator 1.
The OH solution is supplied from the piping 5, and the NaOH solution that has passed through the eIliI chamber 1a is returned to the reading tank 3 from the piping 40.

(5) On the other hand, the liquid with fl+22 miM is piped 50.
50at-, and introduced into activated carbon filtration 86, purified by passing liquid through this activated carbon layer, and then introduced into recovered chemical liquid tank 21 through piping 51. After the chemical liquid is supplied from the cleaning tank 3 to the concentration chamber 1a for a predetermined period of time, this supply is stopped and the first stage cleaning is completed.

(6) After the cleaning of the 2751 Elth element is completed, air is supplied to the concentration chamber 1a through the pipe 5, and the contents in the concentration chamber 1a and the pipe 5.40 are all introduced into the cleaning tank 3.

(7) The liquid taken out into the cleaning tank 3 is extracted from a blow pipe (not shown) to a concentrate tank (not shown) and stored. Note that, depending on the spirit, after the solid-liquid separation #, the liquid may be passed through a washing fi+ device and the filtrate may be introduced into the recovered chemical liquid tank 21.

(8) Next, the second stage of cleaning is performed, that is, the chemical solution in the chemical solution tank 12 is introduced into the washing tank 3 through the pipes 32 and 30.Then, it is passed through the pump 4 and the pipe 5 to the concentration chamber of the component a device 1. 1a and wash the membrane 2. The liquid that has passed through the concentration chamber 1a is returned to the cleaning IPj3 via piping 40. The liquid that has passed through +piz is introduced from the permeation chamber 1b to the recovered chemical tank 22 via piping 50.52. be done. Note that the liquid may be directly returned to the chemical tank via the pipes 50 and 54.

(9) After supplying the chemical solution in the cleaning tank 3 to the concentration chamber 1a for a predetermined period of time, the supply of the chemical solution is stopped, and instead air is supplied to the condensation chamber 1a through the piping 5, and the concentrating chamber 1a, Piping 40
All the contents inside are introduced into the cleaning tank 3.

(lO) The liquid returned to the cleaning tank 3 is treated in the same manner as in (7) above. In addition, when returning the liquid to the recovered chemical liquid tank, the 21211
Finish washing.

(11) Next, 1 liter of medicine and 13 paddle widths of sodium hypochlorite III Jm are introduced into the cleaning tank 3 through the pipes 33 and 30. Then, the sodium hypoalite is introduced into the concentration chamber 1a through the pump 4 and piping 5, and the separation device 1 is sterilized. Preferably, the NaOH is washed away by supplying warm water.

Sodium hypochlorite that passed through nMo2 is piped 50.5
Collected chemical solution +P through 3! Four people were saved on the 23rd.

The sodium hypochlorite 432 element that has passed through the concentration chamber 1a is transferred to pipe 4.
Wash 4f through 0! Returned to 3.

(12) After supplying sodium hypochlorite for a predetermined period of time, this supply is stopped, and then air is introduced into the concentration chamber 1a through the piping 5, and the contents in the piping 5, the concentration chamber 1a, and the piping 40 are The liquid returned to the cleaning tank 3 is returned to the chemical tank 13 through the pipes 70, 40a and 43.

(13) Next, water or hot water is introduced into the membrane separation device 1 to clean the inside thereof.

With the above, the cleaning inside the component #device 1 is completed, and the liquid stored in the 1-recovery chemical solutions 4621 to 23 is transferred to the pipe 61.
~63 and 60.40.40a, and are returned to the chemical tank 11-13 via 41-43. In addition, the recovered chemical tank? The chemical solution in (1) may be returned to either of the chemical solution tanks 11. The liquid in the recovered chemical tank 22 is stored in the chemical tank 22.
It is preferable to return each item to

Note that a predetermined amount (for example, about 10%) of the chemical solution in the chemical tank 11 used for the first cleaning is consumed as the membrane is cleaned, so the amount of the chemical solution used for the first stage cleaning of tjS is The amount decreases. Therefore, a part of the chemical liquid in the recovered chemical liquid 462z may be returned to the chemical liquid tank 11 together with the chemical liquid in the recovered chemical liquid tank 21.

Note that the medicine may be replenished by driving the pump 8.

In the above-mentioned cleaning process, NaOH and sodium hypochlorite are used as the chemical solution, but a surfactant may also be used if necessary. Surfactant chemical liquid tanks are installed in parallel, and surfactant recovery tanks are installed in parallel to the recovery chemical liquid tanks 21 to 24. Cleaning can be easily performed by supplying water using the same cleaning tank 3, piping 5, 50, etc. as in the cleaning procedure described above. In this case as well, the amount of surfactant lost is small, so it can be reused.

[Example] Examples and comparative examples will be described below.

Example 1 A liquid saccharified with cellulose and enzymes was treated with an ultrafiltration membrane having a molecular weight cut off of 20,000 for 20 hours per day.

After 20 hours, operation was interrupted and cleaning was performed using the method of the present invention. The cleaning system is shown in FIG.

Each of the two chemical solution tanks 11 and 12 was filled with 209 0.5% NaOH solution. Also, the chemical tank 13
was filled with a 500 ppm solution of sodium hypochlorite. In washing, first, warm water of 40 to 45°C was passed for 5 minutes. Next, N is supplied from the first chemical tank 11 to the cleaning tank 3.
Transfer the aOH solution, operating pressure 3Kg/rn', 40~4
The solution was passed through membrane separator 1 at 5°C. The standard permeate is pipe 4
0 to the cleaning tank 3. On the other hand, the permeate was passed through the activated carbon tracing tower 6 and then transferred to the recovered chemical solution 4621.

This was done for 10 minutes, and then N was added to the membrane separator 1.
The supply of aOH solution was stopped and air was pumped into component # unit 1, and the concentrate therein was collected in washing tank 3.

Next, an NaOH solution was supplied from the second chemical tank 12 to the cleaning tank 3, and the solution was passed under the same conditions. The permeate was collected as it was in the collected chemical solution 1n22 of S2. Supply pressurized air or sponge pole to the membrane separator l for 10 seconds every 5 minutes,
Washed. After 30 minutes, stop supplying the NaOH solution,
After carrying out the same treatment as above, the system was washed with water and sterilized with a hypotite-tnn acid-resistant thorium solution in the chemical tank 13. Finally, the sodium hypochlorite solution was extruded again using warm water at 40 to 45°C.

When the pH of the NaOH PH solution in the recovered chemical tank 21.22 was investigated, the pH was initially 13.0 in the first recovered chemical tank 21, but it was 12.6 to 12 after use.
．． It was 8. In addition, in the second recovered chemical tank 22, the concentration was 12.8 to 12.9 after use, and although a slight decrease in NaOH concentration was seen in the first stage cleaning, it was found that there was almost no decrease in the second stage cleaning. When using sodium hypochlorite, the initial concentration of 500 ppm was 425 ppm.
pm, and it was recognized that the decrease in concentration was extremely small.

After the cleaning was completed, the NaOH solutions in the recovered chemical liquid tanks 21 and 22 were returned to the chemical liquid tanks 11 and 21, respectively. In addition, the reduced amounts of NaOH and sodium hypochlorite were each replenished.

One cycle consisted of the operation of this component # apparatus and the cleaning process, and a total of 7 cycles were performed. The measurement results of the amount of membrane permeation in each cycle are shown in Table 1, from which it can be clearly seen that the recovery of the amount of membrane permeation was extremely good in all cycles.

Table-1; Recovery tree of membrane permeation amount in each cycle: rn
'/rn'・day Comparative Example 1 The same membrane as in Example 1 was first washed with warm water for 10 minutes, and then
Washed with a 0.5% NaOH solution of Example 1 for 50 minutes, then washed with the same sodium hypochlorite solution as in Example 1 for 50 minutes. After being treated with bacteria, it was extruded with warm water.

This operation was repeated four times in total, but the membrane permeation φ only recovered to 3 m'/rrf-day (1 degree) in each case.

[Effects] As described above, in the membrane cleaning method of the present invention, the conventional method of contacting the required amount of chemical solution with the membrane at once is divided into multiple times and brought into contact with the membrane. , the cleaning effect is high, and the cleaning chemical solution can be used repeatedly. In particular, the chemical solution used in the second and subsequent stages of cleaning is hardly contaminated and can be reused without any treatment. In addition, most of the fouling components of the membrane are
Since it is removed during the cleaning of the first stage, the cleaning process for the chemical solution requires only the chemical solution that has been cleaned in the first stage, and the amount thereof is therefore small.

As described above, according to the present invention, membranes can be cleaned efficiently and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the present invention. 1... Extramembranous a device, ?・・・・・・Membrane, 3・
. . . Cleaning tank, 6 . . . Activated carbon saponification tower, 11 to 13 . . . Chemical liquid tank, 21 to 23 . . . Recovery chemical liquid tank.

Claims (9)

[Claims] (1) In a method of cleaning an ultrafiltration membrane or a microfiltration membrane contaminated with organic matter in multiple stages using a chemical solution by dividing it into n stages (n is a natural number of 2 or more), there are provided n chemical tanks and a chemical solution cleaning method. (1) After first performing the first stage cleaning of cleaning the membrane with the chemical stored in the first chemical tank, (2) Perform at least one cleaning after the second stage, in which the membrane is cleaned using a chemical solution stored in a chemical tank different from the chemical tank used for the previous stage cleaning, and After the membrane permeated liquid for eye cleaning passes through the chemical cleaning device, the membrane permeated liquid for the second and subsequent cleanings is returned to one of the chemical tanks without passing through the chemical cleaning device, and A method for cleaning a membrane in a membrane separation device, characterized in that a chemical solution returned to the membrane is stored for use in the next cleaning. (2) N collection chemical liquid tanks are installed separately from the chemical liquid tank, and the membrane permeate liquid from each stage is temporarily stored in the recovered chemical liquid tank, and then returned to one of the chemical liquid tanks after the cleaning process of each stage is completed. A cleaning method according to claim 1, characterized in that: (3) The cleaning method according to claim 1 or 2, wherein the chemical liquid tank to which the chemical liquid is returned is a chemical liquid tank in which the chemical liquid was stored before cleaning. (4) The cleaning method according to any one of claims 1 to 3, wherein the chemical solution is an alkaline solution. (5) Any one of claims 1 to 3, wherein the chemical solution is an alkaline solution and a sodium hypochlorate solution, each of which is stored in a separate chemical tank. Cleaning method described in. (6) The first claim is characterized in that the chemical solutions are an alkaline solution, a sodium hypochlorite solution, and a surfactant solution, each of which is stored in a separate chemical tank.
The cleaning method according to any one of Items 1 to 3. (7) Claim 5 or 6, characterized in that the n-th stage is cleaning performed using sodium chlorate.
Cleaning method described in section. (8) Any one of claims 1 to 7, characterized in that the membrane is cleaned with water or hot water before the first stage cleaning and after the nth stage cleaning, respectively. Cleaning method described in section. (9) The cleaning method according to any one of claims 1 to 7, wherein the organic matter is derived from a cellulose saccharified solution using an enzyme.