JP2023135069A - Separation recovery method of microorganism and separation recovery device of microorganism - Google Patents

Abstract

To provide a separation recovery method of a microorganism and a separation recovery device of a microorganism which enable suppression of clogging of hollow fiber membranes and furthermore enable microorganisms to be stably separated and recovered at higher concentration.SOLUTION: A separation recovery method of a microorganism according to the present invention comprises: a first step of separating and concentrating a microorganism in liquid S1 by using a hollow fiber membrane; a second step of peeling the microorganism by performing reverse passage of the hollow fiber membrane; a third step of supplying compressed air to the hollow fiber membrane and extruding and recovering microorganism concentration water; a fourth step of cleaning the hollow fiber membrane by reversely cleaning the hollow fiber membrane by a liquid amount smaller than that of the reverse passage in the second step after extruding the microorganism concentration water in the third step; and a fifth step of supplying the compressed air to the hollow fiber membrane thereby discharging the cleaning water. A separation recovery device 1 of a microorganism according to the present invention comprises: first means which performs the first step; second means which performs the second step; third means which performs the third step; fourth means which performs the fourth step; and fifth means which performs the fifth step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for separating and recovering microorganisms and an apparatus for separating and recovering microorganisms.

In recent years, microorganisms, particularly microalgae, have attracted attention as materials for biomass fuels, foods, cosmetics, etc., and the cultivation of microorganisms in large-scale plants has been actively carried out. When using microorganisms industrially, it is usually necessary to separate, concentrate, and recover the microorganisms from the culture solution.
As a method for recovering microorganisms, in recent years, methods have been put into practical use that collect microorganisms with a high recovery rate by filtering culture fluid using separation media such as mesh filters and membrane filters (for example, see Patent Document 1) ).

However, the method of treating culture fluid using a separation medium has problems such as the separation medium becoming clogged with microorganisms, their secretions, culture fluid components, etc., which increases chemical cleaning costs and reduces equipment operating efficiency. be.
To solve this problem, we use a spring-type filter whose filtration surface is pre-coated with a pre-coat material, and by filtering the culture solution with this spring-type filter, we concentrate the microorganisms using the difference in specific gravity between the microorganisms and the pre-coat material. A method has been proposed in which microorganisms are recovered by separating a precoat material from a liquid (see, for example, Patent Document 2). According to this method, since the precoat layer is updated one after another, clogging is reset each time, allowing stable long-term operation.

In addition, in internal pressure filtration devices that flow raw water inside a tubular filtration membrane and flow permeated water toward the outer surface of the membrane, this filtration operation is interrupted and backwash water is flowed from the outer surface of the membrane toward the inner surface. , a method has been proposed in which microorganisms deposited on the inside are peeled off and the separated microorganisms are pushed out from the end of the tube (for example, see Patent Document 3). According to this method, not only microorganisms deposited on the membrane but also substances that clog the membrane can be cleaned and removed.
In addition, as a method for reducing the amount of backwash water required in the internal pressure filtration device described above, a coagulation filtration method has been proposed in which a flocculant is added to raw water to generate flocs, and then solid-liquid separation is performed in the filtration device. (For example, see Patent Document 4).

Japanese Patent Application Publication No. 2014-150768 JP2018-42470A Japanese Patent Application Publication No. 6-190251 Japanese Patent Application Publication No. 2003-170174

However, the method using a precoated spring filter requires a step of separating the precoat material after concentrating the microorganisms, and the separation takes a lot of time. Furthermore, if the separation is incomplete, there is also the problem that the precoat agent may be mixed into the microorganisms.
In the method of flushing backwash water to remove microorganisms that have accumulated inside the membrane, there is a concentrated liquid inside the membrane at the end of the filtration operation, so if a large amount of backwash water is flowed to improve cleaning efficiency, the concentrated liquid will be diluted. It ends up. Conversely, if the amount of backwash water is reduced in order to suppress dilution, there is a problem that the inner surface of the membrane cannot be sufficiently washed.
In the method of adding a flocculant and performing filtration, the flocculant remains in the microorganism concentrate. Therefore, when microorganisms are used as raw materials for feed, fertilizer, or pharmaceuticals, for example, it is necessary to separate the remaining flocculant, which poses a problem of complicating the process.
An object of the present invention is to provide a method for separating and recovering microorganisms and a device for separating and recovering microorganisms that can stably separate and recover microorganisms at a higher concentration while suppressing clogging of hollow fiber membranes.

As a result of intensive study on a method for separating and recovering microorganisms from a liquid containing microorganisms by filtration using a hollow fiber membrane, the inventors of the present invention have found that, before backwashing the hollow fiber membrane, backflow is performed. They discovered that by peeling off and recovering microorganisms attached to the membrane surface, it is possible to stably separate, concentrate, and recover microorganisms at a higher concentration while suppressing clogging of the hollow fiber membrane, and have completed the present invention. Ta.

That is, the present invention has the following aspects.
[1] A step of filtering a liquid S1 containing microorganisms using a hollow fiber membrane to separate and concentrate the microorganisms in the liquid S1;
washing the surface of the hollow fiber membrane while removing microorganisms that have been separated and concentrated from the liquid S1 and attached to the hollow fiber membrane from the hollow fiber membrane by passing liquid through the hollow fiber membrane in reverse; ,
A method for separating and recovering microorganisms from a liquid containing microorganisms, comprising a step of supplying compressed air to the hollow fiber membrane and recovering the microorganisms separated from the hollow fiber membrane as microorganism-concentrated water, the method comprising:
a first step of separating and concentrating the microorganisms in the liquid S1 using the hollow fiber membrane;
a second step of passing liquid backward through the hollow fiber membrane to separate and concentrate microorganisms from the liquid S1 and adhering to the hollow fiber membrane from the hollow fiber membrane;
a third step of supplying compressed air to the hollow fiber membrane, extruding and recovering the microorganisms separated from the hollow fiber membrane from the hollow fiber membrane as microorganism concentrated water;
After extruding the microorganism-concentrated water from the hollow fiber membrane in the third step, a fourth step of backwashing the hollow fiber membrane to clean the surface of the hollow fiber membrane;
a fifth step of supplying compressed air to the hollow fiber membrane and discharging the wash water generated in the fourth step from the hollow fiber membrane;
has
A method for separating and recovering microorganisms, wherein the amount of liquid S2 used for backwashing the hollow fiber membrane in the second step is smaller than the amount of liquid S3 used for backwashing the hollow fiber membrane in the fourth step. .
[2] The method for separating and recovering microorganisms according to [1] above, wherein the filtration is internal pressure filtration.
[3] The method for separating and recovering microorganisms according to [1] or [2] above, wherein the filtration is dead-end filtration.
[4] The method for separating and recovering microorganisms according to any one of [1] to [3] above, wherein the microorganisms are microalgae.
[5] The method for separating and recovering microorganisms according to any one of [1] to [4] above, wherein the washing water is returned to the raw water tank that stores the liquid S1.
[6] The method for separating and recovering microorganisms according to any one of [1] to [4] above, wherein the washing water is discarded.

[7] A first means for filtering a liquid S1 containing microorganisms using a hollow fiber membrane to separate and concentrate the microorganisms in the liquid S1;
a second means for removing microorganisms that are separated and concentrated from the liquid S1 and adhered to the hollow fiber membrane from the hollow fiber membrane by passing liquid through the hollow fiber membrane in reverse;
A third means for supplying compressed air to the hollow fiber membrane, extruding and recovering the microorganisms detached from the hollow fiber membrane from the hollow fiber membrane as microorganism concentrated water;
A fourth means for backwashing the hollow fiber membrane to clean the surface of the hollow fiber membrane after extruding the microorganism-concentrated water from the hollow fiber membrane in the third means;
a fifth means for supplying compressed air to the hollow fiber membrane and discharging the wash water generated in the fourth means from the hollow fiber membrane;
Equipped with
A microorganism separation and recovery device, wherein the amount of liquid S2 used for backwashing the hollow fiber membrane in the second means is smaller than the amount of liquid S3 used for backwashing the hollow fiber membrane in the fourth means. .
[8] The microorganism separation and recovery device according to [7] above, wherein the filtration is internal pressure filtration.
[9] The microorganism separation and recovery device according to [7] or [8], wherein the filtration is dead-end filtration.
[10] The microorganism separation and recovery device according to any one of [7] to [9], wherein the microorganism is a microalgae.
[11] A raw water tank that stores the liquid S1;
The microorganism separation and recovery device according to any one of [7] to [10], comprising a wash water return channel for returning the wash water to the raw water tank.
[12] The microorganism separation and recovery device according to any one of [7] to [10], comprising a wash water waste channel for discarding the wash water.

According to the present invention, it is possible to provide a method for separating and recovering microorganisms and a device for separating and recovering microorganisms that can stably separate and recover microorganisms at a higher concentration while suppressing clogging of hollow fiber membranes.

1 is a schematic configuration diagram schematically showing an example of a microorganism separation and recovery device of the present invention. FIG. 2 is an explanatory diagram schematically showing an example of each step in the method for separating and recovering microorganisms of the present invention.

The method for separating and recovering microorganisms of the present invention is a method of filtering a liquid S1 containing microorganisms to separate and concentrate the microorganisms.
The microorganism separation and recovery device of the present invention is a device that filters a liquid S1 containing microorganisms to separate and concentrate the microorganisms.
EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the method for separating and recovering microorganisms and the apparatus for separating and recovering microorganisms according to the present invention will be described in detail with reference to FIGS. 1 and 2 as appropriate.
In addition, in each drawing used in the following explanation, characteristic parts may be shown enlarged for convenience in order to make the characteristics easier to understand, and the dimensional ratio of each component may differ from the actual one. There is. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be practiced with appropriate changes within the scope of the gist thereof.

[Microorganism separation and recovery device]
FIG. 1 shows an example of the microorganism separation and recovery apparatus of the present invention.
The microorganism separation and recovery apparatus 1 shown in FIG. A permeated water tank 30 for storing, a concentrated water tank 40 for storing microbial concentrated water (hereinafter also simply referred to as "concentrated water") obtained in the membrane module 20, and a supply means 50 for supplying compressed air to the hollow fiber membrane. and a drainage tank 60 for storing wash water generated by backwashing the hollow fiber membrane.

The raw water tank 10 is a tank that stores liquid S1 containing microorganisms. Although details will be described later, depending on the concentration of microorganisms in the wash water generated by backwashing the hollow fiber membrane, at least a portion of the wash water may be received in the raw water tank 10. That is, the raw water tank 10 is a tank that stores the liquid S1, and is also a tank that receives cleaning water as needed.
Further, the raw water tank 10 may be a tank for culturing microorganisms. When culturing microorganisms in the raw water tank 10 in a closed system, it is preferable to use a closed system culture tank as the raw water tank 10. When cultivating microorganisms in a closed system, it is preferable to use an open system culture tank as the raw water tank 10. Preferably, a tank is used.
Here, "closed system" means that the environment of the culture tank is isolated from the environment outside the culture tank. It is preferable to culture the microorganisms in a closed system because the culture of the microorganisms is not easily affected by the environment outside the culture tank and it is possible to prevent foreign substances such as dust from entering the culture tank.

Examples of closed culture tanks include photobioreactor type water tanks.
Examples of the photobioreactor type aquarium include a flat plate type aquarium, a tube type aquarium, a sunlight concentrating type aquarium, an internal irradiation type aquarium, and the like.
Examples of open culture tanks include raceway type water tanks. Furthermore, instead of an open culture tank, microorganisms may be cultured in a pond or the like.

The liquid S1 is raw water that contains microorganisms and is subject to separation and concentration.
Examples of the microorganisms contained in the liquid S1 include microalgae, yeast, bacteria, filamentous fungi, and their spores. Among these, microalgae are suitable as biomass fuels and materials for foods, cosmetics, etc., and the microorganism separation and recovery method and microorganism separation and recovery apparatus of the present invention filter the liquid S1 containing microalgae, and Suitable for separating and concentrating microalgae in S1.

Microalgae are unicellular organisms that have a synthetic function and have a body length (longer axis of a cell) of 100 μm or less.
The microalgae to be cultured in the present invention are not particularly limited, but include, for example, blue-green algae, prokaryotic green algae, red algae, gray algae, cryptoalgae, dinoflagellate algae, golden algae, diatoms, brown algae, yellow-green algae, and haptoalgae. , raphid algae (chloroflagellate algae), chlorarachnion algae, euglena algae, prasinoalgae, green algae, and axillary algae. Among these, Euglena, Pseudocolicystis, which is a type of green algae, and Spirulina, which is a type of blue-green algae, are preferred because they contain many nutrients and can be suitably used in foods, cosmetics, and the like.

The raw water tank 10 is connected to a raw water flow path 11 and a wash water return flow path 26, which will be described later.
The raw water channel 11 is a pipe that extracts a portion of the liquid S1, which is raw water, from the raw water tank 10 and supplies the extracted liquid S1 to the membrane module 20. One end of the raw water flow path 11 is connected to the raw water tank 10, and the other end is connected to a first common flow path 22 and a concentrated water flow path 24, which will be described later, at a first branch point B1. The liquid S1 is supplied to the membrane module 20 via the membrane module 20.

In the middle of the raw water channel 11, a raw water valve 11a and a raw water pump 11b are installed.
The raw water valve 11a is a means for adjusting the amount of liquid S1 supplied to the membrane module 20. Further, supply and stop of the liquid S1 to the membrane module 20 can be switched using the raw water valve 11a.
The raw water pump 11b is a means for extracting the liquid S1 stored in the raw water tank 10 from the raw water tank 10 and supplying it to the membrane module 20 under pressure.

The membrane module 20 includes a hollow fiber membrane (not shown).
The membrane module 20 is a means for filtering the liquid S1 introduced into the hollow fiber membrane to separate and concentrate microorganisms in the liquid S1.
The filtration method of the membrane module 20 may be a dead-end filtration method or a cross-flow filtration method, but the dead-end filtration method is preferable. That is, the filtration of the liquid S1 is preferably dead-end filtration.
The dead-end filtration method is a method in which the entire amount of supplied water is passed through a filtration membrane to perform filtration, and a cake (microorganisms, etc., which is a filtration residue in this embodiment) is attached to the filtration membrane. On the other hand, the cross-flow filtration method suppresses the accumulation of suspended matter and colloids (microorganisms in this embodiment) in the supplied water on the filtration membrane by flowing the supplied water parallel to the filtration surface. This method performs filtration while
The membrane module 20 of this example filters the liquid S1 using a dead-end filtration method.

Types of hollow fiber membranes include microfiltration membranes, ultrafiltration membranes, and the like.
The average pore diameter of the micropores formed in the microfiltration membrane is preferably 0.1 to 1 μm. The average pore diameter of the micropores formed in the ultrafiltration membrane is preferably 0.001 to 0.1 μm. If the average pore diameter of the micropores is equal to or larger than the above lower limit, the pressure required for solid-liquid separation can be suppressed to a sufficiently low level. If the average pore diameter of the micropores is below the above upper limit, microorganisms will be less likely to leak into the separated liquid.

Examples of the material for the hollow fiber membrane include cellulose, polyolefin, polysulfone, polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE). Among these, PVDF, PTFE, and PES are preferable as the material for the hollow fiber membrane because of their chemical resistance and resistance to pH changes.
The outer diameter of the hollow fiber membrane is preferably 0.01 to 3 mm, more preferably 0.05 to 1 mm. If the outer diameter of the hollow fiber membrane is equal to or larger than the above lower limit, a sufficient inner diameter of the hollow part of the hollow fiber membrane can be secured, so that blockage of the hollow fiber membrane by solids contained in the feed water supplied to the hollow fiber membrane can be prevented. can be suppressed. If the outer diameter of the hollow fiber membrane is equal to or less than the above upper limit value, it is possible to suppress the filling amount of the membrane from becoming small when forming the membrane into a membrane module.
The outer diameter of the hollow fiber membrane means the diameter of the smallest circle inscribed in the outer edge of the cut surface when cut at any plane perpendicular to the longitudinal direction of the hollow fiber membrane. The above is determined as an average value measured at 10 or less locations.

The membrane module 20 in this example performs pressure filtration. The pressurization method is not particularly limited, and may be an internal pressure method or an external pressure method, but an internal pressure method is preferable. That is, internal pressure filtration is preferable for the filtration of the liquid S1.
Here, the internal pressure method is a filtration method (in-out method) in which feed water is passed inside the hollow fiber membrane and permeated water is obtained on the outside. The external pressure type is a filtration method (out-in method) in which feed water is passed outside the hollow fiber membrane and permeated water is obtained inside.

A permeate flow path 21 , a first common flow path 22 , and a second common flow path 23 are connected to the membrane module 20 . Further, the membrane module 20 is connected to a raw water flow path 11 and a concentrated water flow path 24 via a first common flow path 22, and a wash water waste flow path 25 and a wash water waste flow path 25 are connected to the membrane module 20 via a second common flow path 23. A return flow path 26 is connected.
The permeated water channel 21 is a pipe for discharging permeated water that has permeated through the hollow fiber membrane of the membrane module 20, that is, a separated liquid from which microorganisms have been removed from the liquid S1, from the membrane module 20 and supplies it to the permeated water tank 30. One end of the permeated water channel 21 is connected to the membrane module 20, and the other end is connected to the permeated water tank 30.
A permeate valve 21 a is installed in the middle of the permeate flow path 21 . Supply and stop of permeated water to the permeated water tank 30 can be controlled by opening and closing the permeated water valve 21a.

The first common flow path 22 in this example is a flow path that supplies the liquid S1 extracted from the raw water tank 10 and passed through the raw water flow path 11 to the membrane module 20, and is a flow path that supplies the filtration membrane of the membrane module 20. It is also a channel for discharging concentrated water in which microorganisms are concentrated without permeation from the membrane module 20 and supplying it to the concentrated water channel 24. One end of the first common channel 22 is connected to the membrane module 20, and the other end is connected to the raw water channel 11 and the concentrated water channel 24 at a first branch point B1.

The second common flow path 23 in this example is a flow path that discharges wash water generated when the hollow fiber membrane of the membrane module 20 is backwashed from the membrane module 20 and supplies it to the wash water waste flow path 25. It is also a flow path that supplies the wash water to the wash water return flow path 26. One end of the second common channel 23 is connected to the membrane module 20, and the other end is connected to the wash water waste channel 25 and the wash water return channel 26 at a second branch point B2. The wash water discharged from the membrane module 20 and passed through the second common flow path 23 is discarded via the wash water waste flow path 25 or returned to the raw water tank 10 via the wash water return flow path 26. do.

The concentrated water channel 24 is a pipe that supplies concentrated water in which microorganisms are concentrated without passing through the filtration membrane of the membrane module 20 to the concentrated water tank 40 . One end of the concentrated water flow path 24 is connected to the first common flow path 22 and the raw water flow path 11 at a first branch point B1, and the other end is connected to the concentrated water tank 40.
A concentrated water valve 24a is installed in the middle of the concentrated water flow path 24. Supply and stop of concentrated water to the concentrated water tank 40 can be controlled by opening and closing the concentrated water valve 24a.

The wash water waste channel 25 is a pipe for discarding wash water generated when the hollow fiber membranes of the membrane module 20 are backwashed. One end of the wash water waste flow path 25 in this example is connected to the second common flow path 23 and the wash water return flow path 26 at the second branch point B2, and the other end is connected to the drain tank 60. The wash water is temporarily stored in the drain tank 60 before being discarded.
A first wash water valve 25a is installed in the middle of the wash water waste channel 25. By opening and closing the first wash water valve 25a, supply and stop of the wash water to the drain tank 60 can be controlled.

The wash water return channel 26 is a pipe that returns wash water generated when the hollow fiber membranes of the membrane module 20 are backwashed to the raw water tank 10. One end of the wash water return flow path 26 in this example is connected to the second common flow path 23 and the wash water waste flow path 25 at a second branch point B2, and the other end is connected to the raw water tank 10.
A second wash water valve 26a is installed in the middle of the wash water return channel 26. By opening and closing the second wash water valve 26a, return and stop of the wash water to the raw water tank 10 can be controlled.

The permeated water tank 30 is a tank that stores permeated water discharged from the membrane module 20.
The permeated water tank 30 is not particularly limited as long as it can store permeated water.
A permeated water flow path 21 and a reverse liquid flow path 31 are connected to the permeated water tank 30 .
The reverse liquid passage 31 is a pipe that supplies at least a portion of the permeated water to the membrane module 20 as a liquid for reverse passage through the hollow fiber membranes of the membrane module 20. One end of the reverse liquid flow path 31 is connected to the permeated water tank 30, and the other end merges with the permeated water flow path 21 on the upstream side (membrane module 20 side) of the permeated water valve 21a of the permeated water flow path 21, A liquid (permeated water) for flowing backward through the hollow fiber membrane can be supplied to the permeated water channel 21.

In the middle of the reverse liquid flow path 31, a reverse liquid valve 31a and a reverse liquid pump 31b are installed.
The back flow valve 31a is a means for adjusting the amount of permeated water supplied to the membrane module 20. Furthermore, supply and stop of permeated water to the membrane module 20 can be switched by the reverse liquid flow valve 31a.
The reverse liquid pump 31b is a means for extracting permeated water stored in the permeated water tank 30 from the permeated water tank 30 and supplying the permeated water under pressure to the membrane module 20 as a liquid for reverse passage through the hollow fiber membrane.

The concentrated water tank 40 is a tank that stores concentrated water discharged from the membrane module 20.
The concentrated water tank 40 is not particularly limited as long as it can store concentrated water.

The supply means 50 is means for supplying compressed air to the hollow fiber membranes of the membrane module 20.
The supply means 50 in this example includes a compressor 51 and a compressed air flow path 52.
The compressed air passage 52 is a pipe for supplying compressed air discharged from the compressor 51 to the membrane module 20. One end of the compressed air passage 52 is connected to the compressor 51. Further, the compressed air flow path 52 branches into two at the third branch point B3, one of which merges with the second common flow path 23 and the other merges with the first common flow path 22. . In addition, in this specification, one branched part is also referred to as a first compressed air flow path 521, and the other branched part is also referred to as a second compressed air flow path 522. That is, in the illustrated example, the first compressed air flow path 521 merges with the second common flow path 23, and the second compressed air flow path 522 merges with the first common flow path 22.

A first compressed air valve 521a is installed in the middle of the first compressed air flow path 521.
A second compressed air valve 522a is installed in the middle of the second compressed air flow path 522.
The first compressed air valve 521a and the second compressed air valve 522a are means for adjusting the amount of compressed air supplied to the hollow fiber membranes of the membrane module 20. Moreover, supply and stop of compressed air to the hollow fiber membranes of the membrane module 20 can be switched using the first compressed air valve 521a and the second compressed air valve 522a.

The drain tank 60 is a tank that stores cleaning water discharged from the membrane module 20.
The drainage tank 60 is not particularly limited as long as it can store wash water.

[Method for separating and recovering microorganisms]
An example of the method for separating and recovering microorganisms of the present invention will be described below. The microorganism separation and recovery method described below is an example of a microorganism separation and recovery method using the microorganism separation and recovery apparatus 1 shown in FIG.
The method for separating and recovering microorganisms of this embodiment includes a step (A) of filtering a liquid S1 containing microorganisms using a hollow fiber membrane, separating and concentrating the microorganisms in the liquid S, and a step (A) of back-flowing the liquid through the hollow fiber membrane. step (B) of cleaning the surface of the hollow fiber membrane while peeling the microorganisms separated and concentrated from the liquid S1 and attached to the hollow fiber membrane from the hollow fiber membrane; and supplying compressed air to the hollow fiber membrane. , a step (C) of recovering the microorganisms detached from the hollow fiber membrane as microorganism-concentrated water, and specifically includes the following first step, second step, third step, and third step. It has four steps and a fifth step.
First step: step (A1) of separating and concentrating microorganisms in liquid S1 using a hollow fiber membrane.
Second step: A step (B1) in which microorganisms that are separated and concentrated from the liquid S1 and adhered to the hollow fiber membranes are peeled off from the hollow fiber membranes by passing liquid backward through the hollow fiber membranes.
Third step: A step (C1) of supplying compressed air to the hollow fiber membrane, extruding the microorganisms separated from the hollow fiber membrane from the hollow fiber membrane as microorganism concentrated water, and recovering them.
Fourth step: After extruding the microorganism-concentrated water from the hollow fiber membrane in the third step (C1), the hollow fiber membrane is backwashed to wash the surface of the hollow fiber membrane (B2).
Fifth step: A step of supplying compressed air to the hollow fiber membrane and discharging the wash water generated in the fourth step from the hollow fiber membrane.
Specifically, it is as follows.

<First step>
Open the raw water valve 11a provided in the middle of the raw water flow path 11 and the permeated water valve 21a provided in the middle of the permeated water flow path 21, drive the raw water pump 11b, and extract a part of the liquid S1 from the raw water tank 10. The liquid S1 is supplied under pressure to the membrane module 20 via the raw water channel 11 and the first common channel 22. At this time, valves other than the raw water valve 11a and the permeated water valve 21a, that is, the concentrated water valve 24a, the first wash water valve 25a, the second wash water valve 26a, the reverse flow valve 31a, and the first compressed air valve 521a And the second compressed air valve 522a is kept closed.
The liquid S1 is filtered by the hollow fiber membrane of the membrane module 20. Although the filtration in this embodiment is dead-end filtration, it may also be cross-flow filtration. Further, the filtration may be performed by internal pressure filtration or external pressure filtration, but internal pressure filtration is preferred.

The permeated water that has permeated the hollow fiber membrane of the membrane module 20 is discharged from the membrane module 20, is supplied to the permeated water tank 30 via the permeated water channel 21, and is stored therein.
The microorganisms contained in the liquid S1 do not pass through the hollow fiber membrane, but are deposited on the surface of the hollow fiber membrane. As shown in FIG. 2, when liquid S1 is internally pressure filtered, microorganisms are deposited on the inner surface of the hollow fiber membrane, and when liquid S1 is externally pressure filtered, microorganisms are deposited on the outer surface of the hollow fiber membrane. .
By filtering the liquid S1 with the hollow fiber membrane in this way, the microorganisms in the liquid S1 can be separated from the liquid S1 and concentrated.

<Second process>
Next, the raw water pump 11b is stopped, the raw water valve 11a and the permeated water valve 21a are closed, the reverse liquid valve 31a provided in the middle of the reverse liquid flow path 31 is opened, and the reverse liquid pump 31b is driven. A portion of the permeated water is extracted from the permeated water tank 30 and supplied under pressure to the membrane module 20 via the reverse liquid flow path 31 and the permeated water flow path 21 as a liquid S2 for back-flowing the hollow fiber membrane. Reverse flow the membrane. At this time, when the liquid S1 is filtered using an internal pressure method in the first step, it is preferable that the liquid flowing backward through the hollow fiber membrane is performed using an external pressure method, and when the liquid S1 is filtered using an external pressure method, the hollow fiber membrane is It is preferable that the reverse liquid flow be performed using an internal pressure method.
By passing the liquid through the hollow fiber membrane in this manner, as shown in FIG. 2, the microorganisms that are separated and concentrated from the liquid S1 and attached to the hollow fiber membrane can be peeled off from the hollow fiber membrane. The microorganisms separated from the hollow fiber membrane are retained within the hollow fiber membrane along with the liquid S2.

<Third process>
Next, the reverse liquid pump 31b is stopped, the reverse liquid valve 31a is closed, and the first compressed air valve 521a provided in the middle of the first compressed air flow path 521 of the supply means 50 and the concentrated water flow path are closed. 24, the concentrated water valve 24a is opened, the compressor 51 is driven, and the compressed air is passed through the compressed air flow path 52, the first compressed air flow path 521, and the second common flow path 23. It is supplied to the hollow fiber membrane of the membrane module 20.
By supplying compressed air to the hollow fiber membrane in this way, as shown in FIG. It is extruded from the membrane, stored in the concentrated water tank 40 via the first common channel 22 and the concentrated water channel 24, and collected.

<Fourth process>
Next, the compressor 51 is stopped, the first compressed air valve 521a and the concentrated water valve 24a are closed, the reverse liquid flow valve 31a provided in the middle of the reverse liquid flow path 31 is opened, and the reverse liquid flow pump 31b is turned on. Driving, part of the permeated water is extracted from the permeated water tank 30, and supplied under pressure to the membrane module 20 via the reverse liquid channel 31 and the permeated water channel 21 as a liquid S3 for backwashing the hollow fiber membrane, Backwash the hollow fiber membrane. At this time, the liquid S2 and The amount of liquid S4 supplied to the membrane module 20 is adjusted. In addition, in the first step, when the liquid S1 is filtered using an internal pressure method, it is preferable to backwash the hollow fiber membrane using an external pressure method; when the liquid S1 is filtered using an external pressure method, the hollow fiber membrane is backwashed. It is preferable to use an internal pressure method.
By backwashing the hollow fiber membrane in this manner, as shown in FIG. 2, microorganisms remaining on the hollow fiber membrane can be removed from the hollow fiber membrane, and the surface of the hollow fiber membrane can be cleaned. The microorganisms separated from the hollow fiber membrane are retained within the hollow fiber membrane along with the liquid S3.

The fourth step is a step carried out after extruding the microorganism-enriched water from the hollow fiber membrane in the third step. As long as all of the microbial concentrated water retained in the hollow fiber membrane has been extruded from the hollow fiber membrane, the fourth step may be performed before the microbial concentrated water is collected in the concentrated water tank 40, or The fourth step may be performed at the same time as the water is collected, or the fourth step may be performed after collecting the microorganism-enriched water, but it is preferable to perform the fourth step after collecting the microorganism-enriched water. .
Note that when backwashing the hollow fiber membrane, a chemical may be used in combination, and for example, the chemical may be added to the liquid S3 in the middle of the reverse liquid flow path 31.

<Fifth process>
Next, the reverse liquid pump 31b is stopped, the reverse liquid valve 31a is closed, and the second compressed air valve 522a provided in the middle of the second compressed air flow path 522 of the supply means 50 and the cleaning water are disposed of. The first wash water valve 25a provided midway through the flow path 25 is opened, the compressor 51 is driven, and the compressed air is passed through the compressed air flow path 52, the second compressed air flow path 522, and the first common flow. The hollow fiber membranes of membrane module 20 are fed via channel 22 .
By supplying compressed air to the hollow fiber membrane in this way, as shown in FIG. is discharged from. The discharged wash water is once stored in the drain tank 60 via the second common channel 23 and the wash water waste channel 25, and then is discarded.

When there are many microorganisms remaining in the hollow fiber membrane after the third step, that is, when the concentration of microorganisms in the washing water is high, the washing water may be returned to the raw water tank 10 as follows.
That is, after the fourth step, the reverse liquid flow pump 31b is stopped, the reverse liquid flow valve 31a is closed, and the second compressed air provided in the middle of the second compressed air passage 522 of the supply means 50 is supplied. The valve 522a and the second wash water valve 26a provided midway in the wash water return flow path 26 are opened, the compressor 51 is driven, and the compressed air is passed through the compressed air flow path 52 and the second compressed air flow path. 522 and the first common flow path 22 to the hollow fiber membranes of the membrane module 20 .
By supplying compressed air to the hollow fiber membrane in this way, as shown in FIG. is discharged from. The discharged wash water is returned to the raw water tank 10 via the second common flow path 23 and the wash water return flow path 26.

In the fifth step, whether to discard the wash water or return it to the raw water tank 10 may be determined depending on the concentration of microorganisms in the wash water, or depending on whether or not chemicals are used during backwashing of the hollow fiber membrane. You may decide. For example, if the concentration of microorganisms in the wash water is low or if a chemical is used during backwashing of the hollow fiber membrane, it is preferable to discard the wash water. If the concentration of microorganisms in the wash water is high and no chemicals are used during backwashing of the hollow fiber membrane, it is preferable to return the wash water to the raw water tank 10.

[Effect]
As mentioned above, by performing step (A), step (B), and step (C), not only microorganisms deposited on the membrane but also substances that clog the membrane can be cleaned and removed. Since a concentrated liquid is present in the membrane at the end of the filtration operation, if a large amount of backwash water is flowed in order to improve cleaning efficiency, the concentrated liquid will be diluted. Conversely, if the amount of backwash water is reduced in order to suppress dilution, there is a problem that the inner surface of the membrane cannot be sufficiently washed.

However, in the method for separating and recovering microorganisms and the apparatus for separating and recovering microorganisms of this embodiment, the step (B) is divided into a second step (B1) and a fourth step (B2). Specifically, in the second step (B1), the amount of liquid S2 necessary for detaching microorganisms is used to reversely flow through the hollow fiber membrane, so the amount of liquid S2 is only a small amount, and the hollow fiber membrane dilution of the microorganism-concentrated water held within can be minimized. Furthermore, in the fourth step (B2), backwashing is performed with liquid S3 in the amount of water necessary for cleaning the membrane surface, but the wash water after backwashing is either discarded or returned to the raw water tank that stores liquid S1 before filtration. Therefore, the microbial concentrate is difficult to dilute.
In addition, there is no need for additional separation steps resulting from carrying out the present invention, and increases in initial investment and running costs are extremely small.
Therefore, according to the method for separating and recovering microorganisms and the apparatus for separating and recovering microorganisms of the present embodiment, microorganisms can be stably separated and recovered at a higher concentration while suppressing clogging of the hollow fiber membrane.

In this embodiment, the membrane module 20 described above corresponds to a first means for filtering the liquid S1 containing microorganisms using a hollow fiber membrane to separate and concentrate the microorganisms in the liquid S1. The first means is a means for implementing the first step.
In addition, the permeated water tank 30, the reverse liquid passage 31, the reverse liquid valve 31a, the reverse liquid pump 31b, and a part of the permeated water passage are configured to reversely pass liquid through the hollow fiber membrane to separate and concentrate from the liquid S1. This corresponds to the second means for peeling off microorganisms attached to the hollow fiber membrane from the hollow fiber membrane. The second means is a means for implementing the second step.
In addition, among the supply means 50, the compressor 51, the compressed air passage 52, the first compressed air passage 521, the first compressed air valve 521a, a part of the second common passage 23, the first common The flow path 22, the concentrated water flow path 24, the concentrated water valve 24a, and the concentrated water tank 40 supply compressed air to the hollow fiber membrane, and the microorganisms separated from the hollow fiber membrane are pushed out from the hollow fiber membrane as microorganism concentrated water and collected. This corresponds to the third method. The third means is a means for implementing the third step.
In addition, the permeated water tank 30, the reverse liquid passage 31, the reverse liquid valve 31a, the reverse liquid pump 31b, and a part of the permeated water passage are operated after the microbial concentrated water is pushed out from the hollow fiber membrane in the third means. This corresponds to the fourth means of backwashing the hollow fiber membrane and cleaning the surface of the hollow fiber membrane. The fourth means is a means for implementing the fourth step.
Further, among the supply means 50, the compressor 51, the compressed air passage 52, the second compressed air passage 522, the second compressed air valve 522a, a part of the first common passage 22, and the second The common flow path 23 corresponds to a fifth means for supplying compressed air to the hollow fiber membrane and discharging the wash water generated by the fourth means from the hollow fiber membrane. The fifth means is a means for implementing the fifth step.

Note that the method for separating and recovering microorganisms and the apparatus for separating and recovering microorganisms of the present invention are not limited to those described above.
For example, compressed air may be used instead of permeated water when backflowing and backwashing the hollow fiber membrane. That is, in the second step, compressed air may be supplied to the hollow fiber membrane to separate and concentrate the microorganisms that have adhered to the hollow fiber membrane from the liquid S1 and peel them from the hollow fiber membrane. Furthermore, in the fourth step, compressed air may be supplied to the hollow fiber membrane to clean the surface of the hollow fiber membrane.
Furthermore, the temperature inside the membrane module decreases due to a decrease in air temperature, which may increase the viscosity of the liquid S1 and reduce the separation performance. In such a case, the membrane module may be provided with a heating means that can heat the membrane module from the inside or outside.
In addition, in the microorganism separation and recovery apparatus 1 shown in FIG. 1, the longitudinal direction of the hollow part of the hollow fiber membrane is the vertical direction, and the concentrated water is pushed out from the hollow fiber membrane in a downward direction in the vertical direction, and the washing water is pushed out in the hollow part in the upward direction in the vertical direction. Although the concentrated water is discharged from the hollow fiber membrane, the concentrated water may be extruded vertically upward from the hollow fiber membrane, or the washing water may be discharged vertically downward.

1 Microorganism separation and recovery device 10 Raw water tank 11 Raw water flow path 11a Raw water valve 11b Raw water pump 20 Membrane module 21 Permeated water flow path 21a Permeated water valve 22 First common flow path 23 Second common flow path 24 Concentrated water flow path 24a Concentration Water valve 25 Wash water waste channel 25a First wash water valve 26 Wash water return channel 26a Second wash water valve 30 Permeate water tank 31 Reverse liquid flow path 31a Reverse liquid valve 31b Reverse liquid pump 40 Concentrate water tank 50 Supply means 51 Compressor 52 Compressed air passage 521 First compressed air passage 521a First compressed air valve 522 Second compressed air passage 522a Second compressed air valve 60 Drain tank S1 Liquid containing microorganisms B1 Second First branching point B2 Second branching point B3 Third branching point

Claims (12)

filtering a liquid S1 containing microorganisms using a hollow fiber membrane to separate and concentrate the microorganisms in the liquid S1;
washing the surface of the hollow fiber membrane while removing microorganisms that have been separated and concentrated from the liquid S1 and attached to the hollow fiber membrane from the hollow fiber membrane by passing liquid through the hollow fiber membrane in reverse; ,
A method for separating and recovering microorganisms from a liquid containing microorganisms, comprising a step of supplying compressed air to the hollow fiber membrane and recovering the microorganisms separated from the hollow fiber membrane as microorganism-concentrated water, the method comprising:
a first step of separating and concentrating the microorganisms in the liquid S1 using the hollow fiber membrane;
a second step of passing liquid backward through the hollow fiber membrane to separate and concentrate microorganisms from the liquid S1 and adhering to the hollow fiber membrane from the hollow fiber membrane;
a third step of supplying compressed air to the hollow fiber membrane, extruding and recovering the microorganisms separated from the hollow fiber membrane from the hollow fiber membrane as microorganism concentrated water;
After extruding the microorganism-concentrated water from the hollow fiber membrane in the third step, a fourth step of backwashing the hollow fiber membrane to clean the surface of the hollow fiber membrane;
a fifth step of supplying compressed air to the hollow fiber membrane and discharging the wash water generated in the fourth step from the hollow fiber membrane;
has
A method for separating and recovering microorganisms, wherein the amount of liquid S2 used for backwashing the hollow fiber membrane in the second step is smaller than the amount of liquid S3 used for backwashing the hollow fiber membrane in the fourth step. . The method for separating and recovering microorganisms according to claim 1, wherein the filtration is internal pressure filtration. The method for separating and recovering microorganisms according to claim 1 or 2, wherein the filtration is dead-end filtration. The method for separating and recovering microorganisms according to any one of claims 1 to 3, wherein the microorganisms are microalgae. The method for separating and recovering microorganisms according to any one of claims 1 to 4, wherein the washing water is returned to a raw water tank that stores the liquid S1. The method for separating and recovering microorganisms according to any one of claims 1 to 4, wherein the washing water is discarded. A first means for filtering a liquid S1 containing microorganisms using a hollow fiber membrane to separate and concentrate the microorganisms in the liquid S1;
a second means for removing microorganisms that are separated and concentrated from the liquid S1 and adhered to the hollow fiber membrane from the hollow fiber membrane by passing liquid through the hollow fiber membrane in reverse;
A third means for supplying compressed air to the hollow fiber membrane, extruding and recovering the microorganisms detached from the hollow fiber membrane from the hollow fiber membrane as microorganism concentrated water;
A fourth means for backwashing the hollow fiber membrane to clean the surface of the hollow fiber membrane after extruding the microorganism-concentrated water from the hollow fiber membrane in the third means;
a fifth means for supplying compressed air to the hollow fiber membrane and discharging the wash water generated in the fourth means from the hollow fiber membrane;
Equipped with
A microorganism separation and recovery device, wherein the amount of liquid S2 used for backwashing the hollow fiber membrane in the second means is smaller than the amount of liquid S3 used for backwashing the hollow fiber membrane in the fourth means. . The microorganism separation and recovery device according to claim 7, wherein the filtration is an internal pressure filtration. The microorganism separation and recovery device according to claim 7 or 8, wherein the filtration is dead-end filtration. The microorganism separation and recovery device according to any one of claims 7 to 9, wherein the microorganism is a microalgae. a raw water tank storing the liquid S1;
The microorganism separation and recovery device according to any one of claims 7 to 10, further comprising a wash water return channel for returning the wash water to the raw water tank. The microorganism separation and recovery device according to any one of claims 7 to 10, comprising a wash water waste channel for discarding the wash water.

Images