JP3030470B2 - Method for cleaning porous flat membrane for filtration of hot soy sauce - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for filtering soy sauce,
The present invention relates to a cleaning method for recovering a water permeation flux by cleaning a porous plate-like membrane having a reduced water permeation flux by depositing a fouling substance on the membrane surface.

[0002]

2. Description of the Related Art A membrane separation apparatus provided with a porous membrane as a separation means does not require heat energy and can continuously perform a separation operation. Widely used for separation. However, in such a membrane separation treatment, when the treatment is carried out for a long period of time or when the quality of the undiluted solution is poor, proteins, phosphates, carbonates, etc. Further, so-called fallen substances such as microorganisms are deposited and deposited, resulting in a decrease in the water permeation flux and the separation efficiency of the membrane separation device, and in some cases, the membrane separation device may be damaged.

[0003] Generally, in the production of soy sauce, freshly fried soy sauce is conventionally used for the purpose of sterilization, quality improvement, removal of precipitates, and the like.
A warming to a temperature of 80-85 ° C. is performed. The soy sauce processed in this way is called fired soy sauce,
After this burning, it is filtered and shipped as product soy sauce. Conventionally, diatomaceous earth has been used as a filter medium for filtration after this burning, but in recent years, a membrane treatment method of filtering with a porous membrane has been adopted.

However, during the filtration of the burned soy sauce, the coagulated protein is deposited on the membrane surface, and the water permeation flux and the separation efficiency of the membrane separation device are significantly reduced with time. Conventionally, as described above, as a method for cleaning a porous membrane having a reduced water permeation flux due to contamination by a fouling substance and restoring the water permeation flux, hot water, an alkaline aqueous solution,
Alternatively, a method of cleaning using chlorine has been proposed. However, even when such a method is applied to a porous flat membrane having a reduced water permeation flux due to the fallout substance accumulating on the membrane surface during the filtration of the soy sauce, the water permeation flux is not effectively recovered. Thus, there is a need for an effective method for quickly recovering the performance of a membrane separation device used for filtration of such burned soy sauce by a simple method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to meet the above-mentioned demand, and is intended to quickly recover the performance of a porous plate-like membrane by a simple method at the time of filtering hot soy sauce. It is intended to provide a cleaning method.

[0006]

According to the present invention, at the time of filtering hot soy sauce, a fouling substance accumulates on the membrane surface,
In the washing method for recovering the water permeation flux by washing the porous flat membrane having a reduced water permeation flux, the porous flat membrane is washed with an alkaline aqueous solution by a cross-flow filtration method, It is characterized by washing with an aqueous solution by a cross flow filtration method.

[0007] According to the method of the present invention, a porous flat membrane having a reduced water permeation flux due to the deposition of a coagulated protein or other substance on the membrane surface is first subjected to cross-flow filtration using an alkaline aqueous solution. Treatment, mainly to decompose and remove the protein in the fall material, and then to the same treatment with an acid in a cross-flow filtration method to remove phosphate, carbonate, etc. in the fall material. Remove from surface.

Here, the cross-flow filtration system refers to a filtration system in which an alkaline aqueous solution or an acidic aqueous solution is supplied so as to flow along the membrane surface, and a part of the aqueous solution is taken out as a membrane permeate and circulated. In the method of the present invention, an aqueous solution of sodium hydroxide or potassium hydroxide is preferably used as the aqueous alkaline solution, and nitric acid or citric acid is preferably used as the aqueous acid solution. The concentrations of the aqueous alkali solution and the aqueous acid solution do not need to be particularly high, and a concentration of 0.1% by weight or more is usually sufficient.

The porous membrane used in the method of the present invention comprises:
It is sufficient that the membrane performance and the material are not deteriorated by the above-mentioned alkaline aqueous solution or acid aqueous solution, and a porous membrane made of polytetrafluoroethylene or polysulfone is generally preferable.

[0010]

As described above, according to the method of the present invention,
At the time of filtration of the heated soy sauce, a fallout substance is deposited on the surface of the membrane, and the porous flat membrane having a reduced water permeation flux is first formed.
Wash with alkaline aqueous solution by cross-flow filtration,
Then, by washing with an aqueous acid solution by a cross-flow filtration method, the water permeation flux can be easily recovered.

[0011]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. Using a plate-and-frame type filtration device equipped with a porous plate-like membrane made of polytetrafluoroethylene having a membrane pore size of 0.2 μm, the burned soy sauce was filtered.
Over time, the permeate flux dropped to 60 litres / square meter-hour due to membrane fouling by the fouling material.

Then, when a 0.1% by weight aqueous alkali solution at 25 ° C. was circulated through the above-mentioned filtration device for 15 minutes by a cross-flow filtration method, the water permeation flux was recovered to 175 liters / square meter / hour. Next, a 0.1% by weight aqueous citric acid solution was circulated at 25 ° C. for 15 minutes in the same manner as in the cross-flow filtration method, and then left standing for 45 minutes. As a result, the water permeation flux was restored to 1,000 liters / square meter / hour. .

Continuation of the front page (56) References JP-A-53-78665 (JP, A) JP-A-2-63529 (JP, A) JP-A-62-176507 (JP, A) JP-A-61-11108 (JP) JP-A-53-57185 (JP, A) JP-A-4-330823 (JP, A) Patent 2744820 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 65 / 06 A23L 1/238 104

Claims (3)

(57) [Claims] In a washing method for recovering a water permeation flux, a porous substance having a reduced water permeation flux is washed by filtering a fall-out substance on the membrane surface during filtration of the burned soy sauce. Washing a porous plate-like membrane for filtration of hot soy sauce, wherein the porous plate-like membrane is washed with an alkaline aqueous solution by a cross-flow filtration method, and then washed with an acid aqueous solution by a cross-flow filtration method. . 2. The method according to claim 1, wherein the acid is citric acid. 3. The method according to claim 1, wherein the acid is nitric acid.
The method for cleaning a porous plate-like membrane for filtration of burned soy sauce according to the above.