JPH04118032A - Jet flow type filter - Google Patents

Abstract

PURPOSE:To extremely efficiently and economically perform separation, recovery, refining and condensation of each suspended component from a liquid containing various kinds of suspended matter by ejecting the source fluid comprising a fluid containing suspended matter in the perpendicular direction to a filter membrane, and alternately providing ejecting ports and discharge ports for circulation. CONSTITUTION:A cake layer depositing on the surface of a filter membrane is efficiently removed with a jet flow of the source fluid ejected from a fine ejecting port 8, which, as a result, increases the permeation flow rate. This cake layer is deposited in the process of separating a fluid containing suspended matter into the suspended matter and the liquid. In this process, the source fluid is ejected in the perpendicular direction to the filter membrane, and ejecting ports 8 and discharge ports 9 for circulation are alternately disposed. The ejection rate of the source fluid ejected is preferably about >=1m/sec, since, with the higher ejecting rate, the larger effect of scraping the cake layer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a jet stream filter that maintains a particularly high membrane permeation flux.

The jet stream type filter of the present invention is applied to the separation, purification, recovery, concentration, etc. of fluids containing or suspending various polymers, microorganisms, yeast, and fine particles. It can be applied in any case where it is necessary to separate fine particles from a fluid containing them, such as in various suspensions containing fine particles, fermentation liquids or culture liquids, as well as suspensions of pigments, etc. It is also applied in the case of separation, and purifies the gas by separating and removing fine particles from suspended gas containing fine particles.For example, sterilizing nitrogen gas to be filled into pharmaceutical ampoules, positive pressure gas for ultrapure water production equipment. It can also be applied to the production of dust-free, sterile gas for filling as well as dust-free, sterile air for air conditioning in IC manufacturing lines.

(Prior Art) Conventionally, techniques for separating suspended solids from a raw fluid containing suspended solids using a membrane include, for example, reverse osmosis, ultrafiltration, microfiltration, which uses pressure as a driving force. There are electrodialysis methods that use a potential difference as a driving force, and diffusion dialysis methods that use a concentration difference as a driving force. These methods can be operated continuously, can separate, purify, or concentrate without significantly changing temperature or pH conditions during the separation operation, and can separate a wide range of particles, molecules, ions, etc. It is economical because it can maintain a large processing capacity in a small plant, requires little energy for separation operations, and can process low-concentration raw fluids that are difficult to use with other separation methods, so it has been widely implemented. There is. The membranes used in these separation techniques include polymer membranes mainly made of organic polymers such as cellulose acetate, cellulose nitrate, regenerated cellulose, polysulfone, polyacrylonitrile, polyamide, and polyimide, as well as those with heat resistance, chemical resistance, etc. There are porous ceramic membranes that have excellent durability, and ultrafiltration membranes are used when the main purpose is colloid filtration.
In precision filtration aimed at filtering fine particles, a precision filtration membrane having micropores suitable for the purpose is used.

In recent years, with the progress of biotechnology, higher purity, higher performance, and higher precision have been required, and the fields of application of microfiltration or ultrafiltration technology are expanding. However, when separating fine particles using a membrane in precision filtration or ultrafiltration, a cake layer forms due to the influence of concentration polarization, creating resistance to the flow of the permeate fluid.
There is also the problem that the resistance due to membrane clogging increases and the membrane permeation flux suddenly and significantly decreases.
This was the biggest reason for preventing the practical application of precision filtration or ultrafiltration. Furthermore, the membrane used therein is easily contaminated, and measures to prevent this are required. As for the filtration method,
There is a so-called dead-end filtration system in which all the fluid to be filtered passes through a filter medium (filter cloth, membrane, etc.) and a cake layer to separate particulates contained in the fluid. In this dead-end filtration system, in order for the fluid to pass through and the suspended solids to be separated, pressure must be applied to overcome the resistance of the filter medium and cake layer that impedes the flow of the fluid. In filtration, if such dead-end filtration is performed, the membrane permeation flux becomes small. For this reason, a cross-flow type filtration method was considered. In this cross-flow filtration system, the raw fluid to be filtered is passed parallel to the membrane surface of the filtration membrane, the fluid passes through the filtration membrane to the opposite side, and the flow of the raw fluid and the permeated fluid are perpendicular to each other. Therefore, this cross-flow filtration method is called as such because the flow of the raw fluid parallel to the membrane strips off the cake layer formed on the membrane surface, making the membrane thinner than the traditional dead-end filtration method. It has a large permeation flux and can directly and continuously separate, purify, and concentrate a large amount of raw fluid, and does not require a flocculation agent to improve filtration.
Therefore, no auxiliary agent is mixed into the collected suspended matter, and by controlling the interaction between the membrane's micropore size and the target substance, an extremely pure filtration fluid can be obtained.

However, although the cross-flow filtration method is an advanced separation technology in principle, the biggest problem is the membrane permeation flux, which is larger than that of the dead-end filtration method. There was a problem that a sufficiently high membrane permeation flux could not be obtained even if this method was adopted.

In addition, in the method of injecting slurry liquid at high pressure to a rotating cylindrical filtration membrane as in JP-A-1-307414, in the part where the injected slurry liquid directly hits the filtration membrane, it accumulates on the surface of the filtration membrane. Although it has the effect of stripping off the remaining cake, there is a problem in that the direct contact flux is low.

(Problems to be Solved by the Invention) As described above, the method of injecting a slurry liquid has the problem that the cake layer on the filtration membrane surface cannot be peeled off and the permeation flux cannot be increased.

In addition, looking at specific examples of conventional separation of suspended solids and fluids, for example, when separating bacterial cells from fermentation liquid, conventional centrifugation, cake filtration, and diatomaceous earth filtration methods are used. Primary filtration, such as filtration, and secondary filtration, such as precision filtration, are used together, but it is difficult to make the process continuous when separating bacterial cells, etc., and products such as enzymes strongly adsorb to the filter aid. The recovery rate decreases, and when bacterial cells are collected by secondary filtration, the membrane permeation flux decreases as the filtration time passes due to the cake layer and clogging formed on the membrane surface. There was a problem in that the centrifugation method resulted in loss of bacterial activity.

By closing the valve on the permeate side of the membrane, the pressure applied perpendicular to the membrane surface of the filtration membrane can be intermittently eliminated or reduced, or pressure can be applied from the permeate side of the filtration membrane to remove the raw fluid from the permeate side. An attempt has been made to intermittently remove the cake layer and adhesion layer deposited on the raw fluid side of the filtration membrane by flowing fluid to the side, which is called "backwashing." However, when such backwashing is performed, in the case of rigid particles, etc., which have a small adsorption force or bonding force between the cake layer, adhesion layer and the membrane,
After "backwashing", the permeation flux recovers to the permeation flux at the beginning of filtration, but in the case of highly adsorbent and highly compressible suspended substances such as yeast and microorganisms, even if "backwashing" is performed, Since the layers and adhesion layers could not be removed sufficiently, the permeation flux did not recover and gradually decreased, and as a result, it was not possible to obtain an economical permeation flux.

(Means and effects for solving the problem) The present invention has been made to solve the problems of the prior art described above, and is a novel and practical method that has a high membrane permeation flux. The object is to provide a jet stream type filter.

That is, in the present invention, for the purpose of separating suspended matter and liquid from a suspension containing suspended matter, raw fluid is discharged perpendicularly to a filtration membrane, and discharge ports and circulation discharge ports are installed alternately. It is characterized by

The present invention will be explained in detail below.

The present invention, when separating suspended solids and liquid from a fluid containing suspended solids, efficiently removes the cake layer deposited on the surface of the filtration membrane using a jet stream discharged from a narrow discharge port of the source fluid. The present invention relates to the structure of a jet stream filter that increases permeation flux. The features of the present invention are
The raw fluid is discharged perpendicularly to the filtration membrane, and the discharge ports and circulation discharge ports are installed alternately. The higher the discharge speed of the raw fluid to be discharged, the greater the effect of peeling off the cake, and it is preferably 1 m/sec or more. Since the surface of the filtration membrane located near the discharge ports has a particularly strong cake layer peeling effect, the shorter the distance between the discharge ports, the better.
It is preferable that it is below.

The present invention is characterized in that raw fluid discharge ports and circulation discharge ports are arranged alternately. In other words, in a jet flow filter, a part of the raw fluid liquid passes through the filtration membrane, and the remaining raw fluid is circulated, so it is necessary to provide a circulation outlet, and in addition, there is a need to provide a circulation outlet to prevent the cake layer deposited on the filtration membrane surface. It is easier to strip the material without compressing it, and it is preferable to reduce the pressure loss in the filter through which the raw fluid flows. In other words, by alternately providing raw fluid discharge ports and circulation discharge ports,
It is possible to reduce the pressure loss inside the filter and not only do not compress the cake layer, but also to form a uniform flow of the raw fluid inside the filter, and as a result, the cake layer is efficiently stripped and a high permeation flux is achieved. Can be retained.

The pore size of the filtration membrane used is preferably a size that does not allow suspended solids to enter the membrane, ie, it is sufficient that it is smaller than the size of the suspended solids. The effect of the present invention is remarkable in the region belonging to the microfiltration membrane, and its surface pore diameter is approximately 0.01 um.
~10 μm.

Next, the present invention using a jet stream type filter will be explained in more detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing a filtration flow using a jet stream type filter. In the figure, a suspension in a supply tank 1 is circulated by a pump 2 through a filter 3 having a built-in filtration membrane. At this time, the pressure of the suspension is regulated by a pressure regulating valve 4. This pressure is read by a pressure gauge 5.6, and the flow rate of the liquid is read by a flow meter 7.

FIG. 2-1 is a cross-sectional view of a jet stream type filter, in which raw fluid enters the filter body and is discharged from the discharge port 8 in a direction perpendicular to the filter membrane. A portion of the raw fluid liquid passes through the filter membrane, and the remainder is returned to the supply tank through the circulation outlet 9. FIG. 2-2 is a plan view thereof.

The structure of the discharge port and the circulation discharge port does not need to be limited to the one illustrated, and any structure may be used as long as they are arranged alternately.

Figure 3 shows a case '2@ on the filtration membrane surface of a jet stream filter.
It is in a state of accumulation. The peeling effect of the cake layer on the filtration membrane surface near the discharge port is large. Figure 44 shows the change in the permeation flux of the E. coli fraction over time when cross-flow filtration is performed with a jet flow filter. It shows.

(Example) The present invention will be explained in more detail with reference to Examples below.
The jet stream type filter of the present invention, which the present invention is not limited to, is as shown in FIG. The discharge port is circular with a diameter of 1 m, and the circulation discharge port has a diameter of 7IlI11.
It is circular. The discharge port and circulation discharge port are installed alternately,
The interval is low. In addition, the distance between the discharge port and the membrane surface is three-dimensional.
The bacterial dispersion was filtered.

Example E. coli (IFO=, 3301) at 0. 9wt, -%
IDryg7・'E (Cb) was dispersed in physiological saline with a nominal pore size of 0°2.
μm (7) Livestock 1a membrane, FM manufactured by Fuji Photo Film Co., Ltd.
Cross flow filtration was performed using 22. The effective membrane area of the module used was 100al, the experimental conditions were a pressure difference (Δp) of 0.5xlO''Pa, and a flow rate of the raw fluid (Q) of 1
The flow rate was 51/min, and the liquid temperature was 25°C.

Figure 4 shows the change in permeation flux over time together with a comparative example in which cross-flow permeation was performed. In the comparative example, the permeation flux sharply decreased 5 minutes after the start of permeation, whereas in the jet flow type filter of the present invention, the initial high permeation flow rate was maintained.

(Effects of the Invention) A superfluous flux is obtained, whereby the separation, recovery, purification, concentration, etc. of each suspended component from a liquid containing various suspended substances can be performed very efficiently and economically. Furthermore, it is possible to make the process continuous and downsize the equipment, and by utilizing the selectivity of the membrane, it is possible to continuously and selectively separate only the target substance, and yeast and bacterial cells can be removed from the reaction solution. By immobilizing it, it can be applied to bioreactors, and compared to conventional technology, it is easier to manage and operate at higher concentrations, and does not require special cleaning to restore membrane permeability. Various effects can be produced.

[Brief explanation of the drawing]

W! , 1 shows a jet stream type filtration device according to the present invention, and FIGS. 2-1 and 2-2 are a sectional view and a plan view showing details of the jet stream type filter. FIG. 3 schematically shows the state in which a cake layer is deposited on the surface of the filtration membrane. FIG. 4 shows the change in permeation flow rate over time during shet flow type filtration (invention) and cross flow filtration (comparative example). Explanation of symbols: ■... Supply 2 Ink 2... Pump 3 ・Filter 4... Pressure adjustment valve 5... Pressure gauge 6... Pressure gauge 7...・・Flow meter・・・Discharge port 9・・・・・Circulation discharge port

Claims (1)

[Claims] 1) In a filter used for the purpose of separating suspended solids and liquid from a suspended solids dispersion, the source fluid consisting of a fluid containing suspended solids is directed perpendicularly to the filtration membrane. A jet flow filter characterized by alternately providing a discharge port and a circulation discharge port. 2) The jet stream type filter according to claim 1, wherein the discharge speed of the raw fluid is 1 m/sec or more, and the distance between the discharge port and the filtration membrane surface is 5 mm or less.