JP2003126663A - Liquid-solid separation apparatus and operation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid-solid separation apparatus capable of removing a solid by filtration, maintaining the filtration performance for a long time, and decomposing organic chlorine compounds such as PCB and dioxins contained in the solid, and an operation method thereof. SOLUTION: The liquid-solid separation apparatus has a plurality of membrane filters 12 each having a filtration membrane layer on the outer surface and having a through-hole coupled together by a hollow member, and comprises a liquid supplying and discharging apparatus 16 supplying a liquid to be treated to the outer surfaces of the plurality of membrane filters and draining a filtered liquid through the hollow of the hollow member, and an ultrasonic cleaner 18 cleaning the outer surfaces of the membrane filters with an ultrasonic wave. The ultrasonic cleaner 18 generates the ultrasonic wave in the frequency range of from about 20 kHz to about 600 kHz, whereby solids deposited on the filtration surface by a shock wave associated with cavitation occurring in water are physically stripped off, and solids are chemically decomposed by an oxidation reaction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid-liquid separation device and a method for operating the same.

[0002]

11 and 12 are schematic views of a conventional leaf filter. A leaf filter is a disk-shaped filter leaf 1 (referred to as a leaf or a filter disc) having a filtration surface on the surface thereof, and the tank is filled with the stock solution to first fill the surface of the filter leaf 1 with the solid matter in the stock solution. It is a solid-liquid separation device that forms a cake first layer, forms a cake layer 2 by filtering the cake first layer, and separates the stock solution 3 into a solid matter 4 (cake) and a filtrate 5. Conventionally, such leaf filters have been widely used for separating chemicals and chemical substances.

Various methods such as rotation, vibration, scraping, and backwashing are used for discharging the cake of the leaf filter depending on its structure. In the example shown in the figure, a rotary drive device 6 for the filter leaf is provided, and after the solid-liquid separation is completed, the filter leaf is rotated at a high speed to move the cake layer 2 to the outside of the filter leaf by centrifugal force, and the scraper is fed from below. 7 or hopper 8 is used to discharge the solid-liquid separation once.

On the other hand, ceramic membrane filters such as MF (cartridge microfiltration membrane) and UF (ultrafiltration membrane) are also widely used for solid-liquid separation. Such a ceramic membrane filter is a hollow cylindrical ceramic pipe or a rod-shaped ceramic having a plurality of hollow cylindrical holes, and a thin filtration membrane layer (fine ceramic powder) is supported by a strong support (coarse ceramic powder). It was done. The filtration membrane layer is usually formed on the inner surface of a hollow cylinder, and the liquid to be treated containing the solid content is pumped inside, and the filtered liquid from which the solid content has been separated / removed from the gap of the fine ceramic powder. It is transparent to the outside. The filtration membrane layer is not limited to the inner surface but may be formed on the outer surface of the ceramic pipe to allow the liquid to be treated to permeate from the outside to the inside.

[0005]

The leaf filters (or leaf type filters) and ceramic membrane filters described above are used in fields requiring solid-liquid separation, such as food processing and wastewater treatment. However, in the conventional solid-liquid separation device using a leaf filter or a ceramic membrane filter, if the separation and removal of solids are continued, the separated solids will be deposited on the surface of the filtration membrane layer, and the filtration performance will gradually deteriorate. There is a problem. Note that, hereinafter, a phenomenon caused by irreversible precipitation of solute on the film surface or in the film is referred to as “fouling”.

Conventionally, as means for solving clogging and fouling, (1) "backwashing" in which compressed air or a part of the filtrate is pressed in a direction opposite to filtration, (2) hypochlorous acid, hydrochloric acid after filtration, "Chemical cleaning", which cleans with chemicals such as caustic soda,
(3) Means for pre-coating a leaf with a powder of cellulose, diatomaceous earth, or the like in advance, draining after filtration, feeding air, drying and rotating the leaf to peel off the cake, and the like have been mainly applied.

However, the recovery of the filtration performance by "backwashing" is effective only for a short time, and the removal of solids is incomplete. Further, in the case of adding “chemical solution cleaning” or “flocculant”, post-treatment (waste solution processing) of the chemical solution used for cleaning, removal of residual chemical solution in the system, etc. are required. Further, there is a possibility that the chemical solution or the coagulant component may remain in the system after washing.

Also, clogging using a pre-coating agent like a leaf filter complicates the operation control of the apparatus.

Furthermore, each of the above-mentioned means not only requires a large amount of energy for eliminating clogging and fouling, but also neither of them can remove the solid matter during the filtration, and the filtration step Had to interrupt.

Further, when the solid content contains an organic chlorine compound such as carbon tetrachloride, chloroethylenes, PCB, dioxin, etc., the solid matter can be separated and removed by the conventional solid-liquid separation device, The harmful component could not be decomposed.

The present invention was created to solve the above-mentioned various problems. That is, the object of the present invention is to remove solids during filtration without interrupting the filtration step, which enables stable maintenance of filtration performance for a long time, and the use of chemicals and flocculants. It is an object of the present invention to provide a solid-liquid separator capable of decomposing organic chlorine compounds such as PCB and dioxin contained in the solid content without the need and an operating method thereof.

[0012]

According to the present invention, a filtration membrane layer (12a) is formed on the outer surface and a through hole (12b).
A plurality of membrane filters (12), a hollow member (14) that connects the plurality of membrane filters at a distance from each other and communicates each through hole in a watertight manner, and the outer surfaces of the plurality of membrane filters to be treated. A liquid supply / discharge device (16) for supplying a liquid and extracting a filtered liquid from a hollow hole of a hollow member, and an ultrasonic cleaning device (18) for ultrasonically cleaning the outer surface of a membrane filter. A solid-liquid separation device is provided.

Further, according to the present invention, (A) a plurality of membrane filters (12) having a filtration membrane layer (12a) formed on the outer surface and having through holes (12b) are connected to each other at intervals. Moreover, the through holes are communicated in a watertight manner, (B) the liquid to be treated is supplied to the outer surfaces of the plurality of membrane filters, and the filtrate is extracted from the through holes of the hollow member, (C) simultaneously, continuously or intermittently. There is provided a method for cleaning a membrane separation device, characterized in that the outer surface of the membrane filter is ultrasonically cleaned.

According to the above apparatus and method of the present invention, a plurality of membrane filters (12) are provided by the liquid supply / discharge device (16).
The liquid to be treated (1) is supplied to the outer surface of the membrane, solid-liquid separation is performed by the filtration membrane layer (12a) formed on the outer surface, and the hollow member (14) is passed through the through hole (12b) of the membrane filter (12). The filtrate (2) can be separated and taken out after passing through the hollow pores. In addition, the filtration membrane layer (12) of the membrane filter (12)
Since a) is formed on the outer surface, compared to the conventional hollow cylindrical inner surface or the outer surface of the pipe, the ultrasonic cleaning device can be easily accessed from the outside even when the filtration area is increased. While cleaning the outer surface of the membrane filter with ultrasonic waves according to (18), at the same time, a plurality of membrane filters (1
The liquid to be treated can be filtered in 2) and the filtered liquid can be withdrawn. Therefore, the outer surface of the membrane filter can be continuously or intermittently washed simultaneously with the filtration, and the solid matter can be removed during the filtration without interrupting the filtration step.

According to a preferred embodiment of the present invention, the ultrasonic cleaning device (18) comprises about 20 kHz to about 600 kHz.
The ultrasonic transducer (18a) is capable of generating ultrasonic waves in the frequency range of kHz.

With this configuration, the ultrasonic transducer (18a)
Ultrasonic waves propagate at high speed to all parts of the water, and the cavitational shock waves generated in the water remove the solids adhering to the filtration surface. Further, particularly at a high frequency of 200 kHz or higher, a chemical reaction due to cavitation occurs, water molecules are decomposed to generate hydroxyl radicals, and an oxidative decomposition reaction due to a radical reaction is caused. Therefore, by changing the ultrasonic irradiation conditions, not only physical peeling at low frequency but also decomposition by chemical reaction at high frequency,
It can be used properly according to the application. Further, conditions such as ultrasonic irradiation time, irradiation cycle, frequency and irradiation energy can be changed according to the properties of the target object.

The membrane filter (12) is a ceramic plate or a sintered metal plate. By using the ceramic plate, it is possible to prevent the membrane filter itself from being consumed by the reaction. Further, by using the sintered metal plate, the strength against ultrasonic waves can be increased.

The membrane filter (12) has a through hole (12
b) is a disk shape having a central hole, and the hollow member (1
4) is a hollow tube, and a plurality of membrane filters (12)
Is provided with a filter rotating device (20) for rotating the hollow member (14) about the axis thereof.

With this structure, the leaf can be rotated during the filtration, so that not only the clogging can be prevented but also the clogging substances (solid particles) on the filtration surface due to ultrasonic irradiation can be removed.
Can facilitate removal.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the common part is denoted by the same reference numeral, and the duplicated description will be omitted.

FIG. 1 is an overall configuration diagram showing a first embodiment of a solid-liquid separation device of the present invention. 2 is a schematic diagram of a membrane filter used in the solid-liquid separation device of the present invention, (A)
Is a perspective view of a use state, and (B) is a partial sectional view.

As shown in FIG. 1, the solid-liquid separation device 10 of the present invention comprises a plurality of membrane filters 12, a hollow member 14, a liquid supply / discharge device 16 and an ultrasonic cleaning device 18.

A plurality (three in this example) of membrane filters 12
Has the filtration membrane layer 12a formed on the outer surface thereof and the through-hole 1
With 2b. As shown in FIG. 2A, the membrane filter 1
2 is a disk-shaped ceramic plate in which the through hole 12b is a central hole in this example. Further, as shown in FIG.
The filtration membrane layer 12a is made of fine ceramic powder, and is supported by a rough and strong support 12c (coarse ceramic powder) inside thereof. With this configuration, the liquid to be treated 1 containing the solid content is filtered by the filtration membrane layer 12a, the solid content 3 is left on the outer surface, and the filtrate 2 permeates through the gaps of the fine ceramic powder into the central hole 12b. It is designed to come out. The membrane filter 12 is not limited to the ceramics plate, and may be a sintered metal plate having a similar structure obtained by sintering metal powder.

The hollow member 14 is a hollow tube in this example, and connects the plurality of membrane filters 12 with a space between each other and connects the through holes in a watertight manner. In FIG. 1, the hollow member 14 includes a plurality of (three in this figure) membrane filters 12
Are concentrically connected to each other with a space therebetween, and each central hole is communicated in a watertight manner. This hollow member 14 is, for example, a spacer tube 14a sandwiched between the filters 12, a gasket (not shown) that seals the inner edge of the filter and the spacer tube in a watertight manner, and passes through the inside of the spacer tube in the entire axial direction. It is composed of a fixed rod 14b to be tightened.

The liquid supplying / discharging device 16 supplies the liquid to be treated to the outer surfaces of the plurality of membrane filters 12 and also extracts the filtrate 2 from the through holes of the hollow member 14 to the outside. The liquid supply / discharge device 16 includes, for example, a treatment liquid tank 16a that surrounds the membrane filter 12 and the hollow member 14 in a watertight manner and immerses them therein, a supply pump (not shown) that supplies the treatment liquid 1 into the treatment liquid tank 16a, And / or a discharge pump (not shown) for extracting the filtrate 2 from the central hole of the hollow member 14 to the outside. The processing liquid tank 16a is a pressure vessel, and the membrane filter 12
It is preferable that the liquid to be treated 1 filled around the can be pressurized to a required pressure.

The ultrasonic cleaning device 18 cleans the outer surface of the membrane filter 12 with ultrasonic waves. This ultrasonic cleaning device 18
Has an ultrasonic transducer 18a capable of generating ultrasonic waves in the frequency range of about 20 kHz to about 600 kHz. The ultrasonic oscillator 18a is, for example, a piezo-type piezoelectric element, and applies a frequency voltage to electrodes (not shown) to generate ultrasonic waves at a desired frequency. Further, in this example, a plurality of resonance blocks 1 are attached to a single mounting plate 18b.
8c are attached, and ultrasonic vibrations are effectively transmitted by being vibrated by the ultrasonic vibrators 18a, respectively, and the vibration density is increased.

Cavitation is generated in water due to ultrasonic vibration, and a shock wave due to cavitation is generated during expansion and compression of the water. By this shock wave, the solid matter adhered to the filtration surface can be physically peeled off. Further, particularly in a high frequency region of about 200 kHz or more, water molecules are decomposed by a chemical reaction by cavitation to generate hydroxyl radicals, and the solid matter attached by the oxidative decomposition reaction by the radical reaction can be chemically decomposed. The phenomenon caused by such ultrasonic waves is disclosed in the following documents.

(Reference 1) Physical Chemistry of Sonochemistry,
Chemical industry, August 1996 (reference 2) sonochemistry, recent developments and future trends, chemical industry, August 1996 (reference 3) ultrasonic decomposition of environmental pollutants, chemical industry, 19
August 1996

The solid-liquid separation device 10 of the present invention further comprises a filter rotation device 20 for rotationally driving the plurality of membrane filters 12 around the axis of the hollow member 14. The filter rotating device 20 is composed of, for example, bearings 20a and 20b that rotatably support the hollow member 14 around an axis, and a rotary drive device 20c that rotationally drives the hollow member 14.

FIG. 3 is an overall configuration diagram showing a second embodiment of the solid-liquid separation device of the present invention. In this figure, the membrane filter 12 is not limited to a disc shape, but may be a rectangle or any other shape. Further, the through hole 12b is not limited to the central hole, and may be provided at any position of the membrane filter 12. Further, in this example, the filter rotating device 20 in the first embodiment is not provided, and the upper and lower ends of the hollow member 14 are watertightly fixed to the treatment liquid tank 16a. Further, in this example, a pair of ultrasonic cleaning devices 18 are provided on the left and right sides in the drawing. Other configurations are similar to those of the second embodiment shown in FIG.

The cleaning method of the present invention using the solid-liquid separation device 10 described above comprises the following steps. (A) The plurality of membrane filters 12 described above are concentrically connected to each other with a space therebetween, and the through holes 12b are connected in a watertight manner. (B) The liquid to be treated 1 is supplied to the outer surfaces of the plurality of membrane filters 12, and the filtered liquid 2 is extracted from the through holes of the hollow member 14 to the outside. (C) At the same time, the outer surface of the membrane filter 12 is continuously or intermittently cleaned with ultrasonic waves.

According to the apparatus and method of the present invention described above,
The liquid to be treated 1 is supplied to the outer surfaces of the plurality of membrane filters 12 by the liquid supply / exhaust device 16, and solid-liquid separation is performed by the filtration membrane layer 12a formed on the outer surfaces, and the through holes 1 of the membrane filter 12 are formed.
The filtrate 2 can be separated and taken out from 2b through the hollow holes of the hollow member 14. Also, the membrane filter 12
Since the filtration membrane layer 12a is formed on the outer surface, it can be easily accessed from the outside even when the filtration area is increased as compared with the conventional hollow cylindrical inner surface or the outer surface of the pipe, and While the outer surface of the membrane filter is ultrasonically cleaned by the sonic cleaning device 18, the liquid to be treated can be filtered by the plurality of membrane filters 12 at the same time and the filtered liquid can be extracted. Therefore, the outer surface of the membrane filter can be continuously or intermittently washed simultaneously with the filtration, and the solid matter can be removed during the filtration without interrupting the filtration step.

[0033]

EXAMPLES Examples of the present invention will be described below.

1. As a method for maintaining and recovering the filtration performance in the current ceramic membrane filtration, regular backwashing of the filtrate during operation is usually performed, but it is unavoidable that the filtration performance deteriorates due to long-term operation. In continuous operation of ceramic membrane filtration, it is important to suppress the degree of filtration rate reduction due to such fouling of the filtration surface and clogging. Further, when the filtration rate is significantly reduced, recovery by chemical cleaning is also required, and there are many adverse effects such as increased cost and reduced filtration efficiency due to securing cleaning time, and reducing the frequency of chemical cleaning is a major issue. Therefore, as a membrane filter element, a filter-type surface-layer-shaped disc-type ceramic membrane that is easy to remove dirt (scale) on the filtration surface and fouling countermeasures is applied, and its effect,
The practicality was examined.

2. Experimental method (1) Experimental device (disk type ceramic membrane) The specifications of the disk type ceramic membrane filter used in this experiment are:
μm, average pore size of support 10 μm, porosity of support about 30
%, The film thickness is about 50 μm, and the alumina purity is 99.8% or more. Since the front, back, and side surfaces are filtration surfaces, the net filtration area is as follows. [Filtration Area (3 Discs)] (Front and Back) φ145 / φ70 × 6 Sides = 0.076m ² (Side Side) 145π × 10 × 3 = 0.014m ² ∴ Total Filtration Area 0.09m ² (0.03m per Sheet) ² )

(Testing Machine) As a testing machine for incorporating a disk type ceramic membrane, a horizontal leaf filter type testing machine (CFR 0.06 type, filtration area 0.0) schematically shown in FIG.
6 m ² ) was used. This apparatus is substantially the same as the solid-liquid separation apparatus of the present invention shown in FIG.

(2) Experimental Items (Measurement of Initial Filtration Rate) It is important to measure the initial filtration rate of the disk-type ceramic membrane from the viewpoint of comparison target values in future ceramic membrane filtration tests.
In this study, the filtration rate was measured by performing filtration using city water. The filtration pressure ΔP = 0.2 Mpa (P
e) Fixed.

(Disc rotation) During filtration and after backwashing the filtrate, the filter nest (assembly of a plurality of filters) was rotated for the purpose of applying a shearing force to the filtration surface of the disc-shaped ceramic membrane. The filtration surface cleaning, the fouling prevention effect and the like by adding the disk rotation were observed. The rotation was performed about 5 to 15 sec / once as a guide. Outer radius: 0.145 m × π × (1450 rpm / 60) = when rotating the disc ceramic membrane of this tester specification
11.0 m / sec Inner circumference: 0.07 m × π × (1450 rpm / 60) =
The linear velocity (in the film surface direction) is 5.3 m / sec. Compared with the fact that the cross flow velocity in the current multi-type media ceramic membrane filtration is usually about 2 to 3 m / sec, the membrane surface relative shear force equal to or higher than that of the cross flow method is obtained intermittently and instantaneously. It is judged that there is.

(Disc wiping and cleaning with a waste cloth) After removing the disk-shaped ceramic membrane that had been clogged by filtration with industrial water, dirt accumulated on the disk filtration surface was lightly wiped with a waste cloth. After that, the filter was reassembled and a filtration test was performed. By comparing the filtration speeds before and after wiping, the effectiveness of the wiping mechanism incorporating a brush and the like at the actual machine level was confirmed.

(Air backwashing) The filter nest was pulled out from the tester, and 0.2 to 10% from the filtrate outlet line below it.
By injecting air of about 0.3 MPa (Pe), it was judged whether or not the back blow by the air was necessary.

(Jet washing) After causing a reduction in filtration speed by industrial water filtration, the operation was stopped, the disk filter was removed, and the fouling on the filtration surface was washed with a high pressure washing machine (Toshiba WP-80B type, maximum pressure 80 bar (81. 6
kgf / cm ² ), discharge water amount 6 Lit. / Min) and the whole surface was washed. Cleaning time is 10-15se per side
It was set to about c.

(Backwashing of filtrate) In ceramic membrane filtration,
It is well known that the filtration rate can be prevented from decreasing over time by performing regular backwashing of the filtrate every few minutes during filtration.
However, the difference in the backwash effect depending on the conditions such as backflow pressure and the amount of backwash liquid has not been clarified. Therefore, the backwashing effect of the filtrate was confirmed together with the difference in the effect due to the difference in the shapes of the Tuchler type and the disc type. A filtrate reservoir tank for backwashing filtrate (internal volume approx. 5
Lit. ) Was installed. The lower inlet line of the filtrate storage tank was used as a filtrate inlet, the upper outlet line was branched in two directions, one was a filtrate outlet, and the other was a backwash pressure air inlet.
A thin flex tube capable of reading the liquid level was attached to the side of the tank to measure the backwash liquid volume by adjusting the scale (backwash liquid volume readable range 1.5Lit.
t. ).

(Ultrasonic Irradiation) Ultrasonic Cleaning Device As an initial test for confirming the filtering surface deposit removal effect by ultrasonic irradiation, an ultrasonic irradiation test was conducted using the ultrasonic cleaning device according to the following procedure. First, the filtration disk was removed by filtering with industrial water, and then the filter disk was removed. Remove the removed disk-shaped ceramic membrane with an ultrasonic cleaner (Shimad
zu, Hi-Power SUS-100 type, output 10
0 W, oscillation frequency 42 kHz, capacity about 3 Lit. ) In order to remove the dirt on the filtering surface uniformly over the three disks. After that, a built-in filtration test was performed again to observe the change in filtration rate before and after ultrasonic irradiation. Since the ultrasonic irradiation for a long time under these conditions may cause damage to the ceramic membrane filtration surface due to cavitation, the irradiation time was set to about 30 to 40 seconds by slowly rotating each disk while immersing the entire surface.

-Ultrasonic irradiation by ultrasonic generator (oscillator (connection horn + chip) shape) When applying an ultrasonic mechanism to a disc-type ceramic membrane filter actual machine level, there are many restrictions on the installation and arrangement of the ultrasonic irradiation device. Will be imposed. Therefore, it is necessary to perform a confirmation test in consideration of physical constraints such as the ultrasonic wave irradiation direction and the irradiation distance. Therefore, an ultrasonic wave generator (Tomy Seiko, UD-201 type, maximum output 200 W, oscillation frequency 2) of an oscillator (connection horn + tip) shaped ultrasonic wave was added to a disk ceramic membrane that had been filtered with industrial water filtered in a container filled with water.
The difference in the cleaning degree was observed by changing the irradiation direction and the irradiation distance to the fouling filtration surface by irradiating ultrasonic waves at 0 kHz). The frequency output was also changed, and the effect was also confirmed.

3. Experimental results (1) Disk-type ceramic membrane filter Initial measurement of filtration speed (RUN1 city water filtration) Filtration pressure ΔP = 0.2 MPa (Pe), total filtration time 131
Instantaneous filtration rate Ri ≈ 800-900L in min operation
it. As shown in FIG. 5, an almost stable value was obtained at about / m ² Hr. In city water filtration, the fouling of the filtration surface is unlikely to occur, and the filtration performance is sufficiently maintained. Also, when the filter nest was rotated for about 5 seconds every 1 minute during operation, there was almost no difference between when the filter was rotated and when it was not rotated. This RU shows the correlation between disk rotation, retention of filtration speed, and recovery of filtration performance.
It is hard to think in N.

(2) Industrial water filtration test (RUN2) Filtration pressure ΔP = 0.2 MPa (Pe) constant, total filtration time θ
= 213 min operation, the filtration rate Ri immediately after the start of operation
≈750 Lit. / M ² Hr, but Ri≈420Lit. / M ² Hr (Fig. 6)
reference). Moreover, the effect of maintaining the filtration rate and recovery by the disc rotation during filtration was not observed. The effect of removing fouling due to the generation of a shear flow due to the rotation of the filter is that intermittent rotation (1 to 1500 rpm) at this rotational speed condition (about 1500 rpm)
2 times / min for about 5 sec) is considered to be unlikely.

(3) City water filtration test (R
UN2) The filtration rate is Ri≈420Lit. / M ²
From Hr to Ri≈600 Lit. Recovery was observed up to about / m ² Hr (ΔP = 0.2 MPa (Pe)). In this test, the disk was wiped after being removed, but if a brush or the like can be incorporated at the actual machine level, the same effect of removing surface fouling can be expected.

(4) Confirmation of airbag blowing effect (RU
N3) The filter nest was removed, and air of about 0.2 to 0.3 MPa (Pe) was injected from the bottom of the filter nest (filtrate line). After that, it is reassembled and a city water filtration test is proposed, but the filtration rate Ri is approximately 400 to 500 Lit. / M
^It decreased to ² Hr. The filtration rate gradually increased with the passage of filtration time, and Ri≈600Lit. / M ² Hr was recovered, and the filterability was recovered to almost the same level as before air blowing. Therefore, it is judged that the air is caught in the filter stack due to the air exposure by the air bag blow and a temporary liquid passing defect occurs, and it is difficult to expect the fouling and clogging removing effect.

(5) Ultrasonic irradiation (RUN4) Remove the filter disk and remove the ultrasonic cleaner (100W,
42 kHz>. Surface stains on the soaked area were removed for about 10 to 15 seconds (from brown to almost white). Similarly, the entire surface of the filtration surface was removed by ultrasonic waves, and then a city water filtration test was performed. The filtration rate is about Ri≈830 Lit. /
m ² Hr, and almost recovered to the initial value obtained from RUN1. It is expected to have a dramatic effect on filterability recovery.

(6) Jet cleaning (RUN5, 7, 8) At RUN5, ΔP = 0.2 MPa (P
e) initial Ri≈600 Lit. / M ² Hr to R
i≈350 Lit. After the filtration speed was reduced to / m ² Hr, the discs were removed, and all three surfaces were cleaned with a jet to remove dirt, and incorporated again to carry out industrial water filtration. As a result, after the restart, Ri≈640Lit. / M ² Hr was recovered to almost the initial value. It is judged that the effect of removing fouling on the surface of the filtration surface by jet cleaning is extremely high. R
Performed the same test as RUN5 in UN7 and 8,
The reproducibility was confirmed.

(7) Filtrate backwash (normal backwash) (RUN6) Filtration time 3 to 8 min, 72 to 90 min, 146-1
By performing the backwashing of the filtrate three times for each 58 minutes, a recovery of the filtration rate of about 10% was instantaneously seen as shown in FIG. 7. The backflow pressure is about 0.3 MPa (Pe) and the backwash water amount is about 5 to 7 Lit. / M ² . Judging from this tendency, it is considered that stable continuous operation can be performed even in the disk-type ceramic membrane filter by setting an appropriate backwash interval.

(High-pressure backwash) (RUN8) After the filtration time of 25 min, the backflow pressure was about 0.4 to O.V. 5M
Pa (Pe), backwashing liquid amount of about 15 to 30 Lit. / M ² ,
In the backwash condition every backwash interval 3-5 min,
As shown in FIG. 8, a filtration rate of 700 was obtained by backwashing three times.
~ 750 Lit. Recovery was observed up to / m ² Hr.

(Correlation between the effect of backwashing of filtrate, backwashing pressure and backwashing liquid amount) (RUN9) During the filtering time of 135 min to 150 min, the backwashing pressure was kept constant at about 0.1 to 0.15 MPa (Pe). Backwash volume about 17 Lit. / M ² , 28 Lit. / M ² , but the filtration rate was hardly recovered. 150
During the period from min to 175 min, the backwash liquid amount was 17 Lit. /
0.25,0.34,0.4 backflow pressure in the m ² and constant
It was changed to MPa (Pe). As a result, as shown in FIG. 9, the filtration rate showed a slight increase tendency. Thereafter, the backwash pressure was 0.
4 to 0.5 MPa (Pe), backwash interval about 5 mi
The initial filtration rate was set to 80 by performing backwashing multiple times at n.
It showed a recovery of about%. From the above results, it is judged that in the backwashing of the filtrate, the condition setting of the backwashing pressure has a stronger influence on the tendency of recovering the filterability than the backwashing liquid amount.

(Effect of reverse washing of filtrate and rotation of disk) R
In UN6, 8 and 9, the disc was rotated immediately after the backwashing of the filtrate, but its effectiveness and specific tendency were difficult to judge only by this test data. However, disk rotation is presumed to have the effect of preventing reattachment of filtration surface fouling separation immediately after filtrate backwashing due to the resulting turbulent surface layer flow. Therefore, the parallel use of filtrate backwashing and disk rotation is highly significant. Think

(8) Ultrasonic irradiation by ultrasonic generator (oscillator (connecting horn + tip) shape) (RUN10) Filtration speed Ri = 333 lit. / M ² Hr After reducing the filtration rate, 3 disk-type ceramic membranes were removed, and the ultrasonic irradiation conditions (output, frequency, irradiation distance, irradiation direction) were changed and irradiation was performed to determine the difference in the effect. did.
Ultrasonic irradiation was performed on the first disk for about 5 minutes at a condition output OUTPUT2 and a distance between the film surface and the oscillator of 10 cm (the irradiation position was the central portion), but the removal of the film surface stain was hardly confirmed by visual judgment. OUTPUT5, distance 5-6cm
At the time of irradiation for about 5 minutes, a few spots of dirt removal were found on the filtering surface on the irradiation direction side. OUTPUT1
0 (output 200W), distance 5-cm, irradiation time 5-12
During irradiation at min, the filter surface on the irradiation direction side was almost entirely cleaned, and the filter surface on the back side was also cleanly cleaned. Next, using the second disc, the OUTPUT 10 (output 200 W), in which good results were obtained with the first disc,
Under the condition of the distance of 5 to 6 cm, the oscillator was set at the end of the disk, and the difference in effect depending on the irradiation position was confirmed. 3 mi
After n, the surface was slightly cleaned, but 15
Some spots were not completely removed even after the lapse of min. Almost no stain removal was confirmed on the back side filtration surface.
OUTPUT1O (output 200
W), when irradiation was performed from the side surface at a distance of 2 cm, only the area adjacent to irradiation was removed, and almost no removal effect was seen on both sides of the filtration surface. After uniformly removing the fouling by ultrasonic irradiation on all three surfaces, the water is filtered again and ΔP = 0.2 MPa (Pe) at the filtration rate Ri =
633Lit. The filtration rate was recovered to / m ² Hr.

(9) Jet cleaning repeated operation (RUN1
1) It was confirmed in RUN 5, 7, and 8 that a high filterability recovery effect can be obtained by jet cleaning. However, in order to stably and continuously operate the disk-type ceramic membrane filter for a long period of time, it is extremely important to carry out the operation a plurality of times and grasp the tendency of the asymptotic value of the filtration rate. It was confirmed by carrying out the removal disk jet cleaning test three times in succession after filtering the industrial water. As shown in FIG. 10, each time the jet cleaning was performed, the recovery of the filtration rate was observed to the same extent as the initial value. In this test, the filtration time was about 125 min, and the jet cleaning was performed 3 times. However, even in the case of longer operating time, it is expected that sufficient filtration speed recovery can be obtained by performing the jet cleaning at an appropriate frequency, and the average filtration is performed. It is suggested that the speed approaches a certain asymptotic value that is sufficient for stable driving.

4. Future direction / problems It is necessary to consider as two factors as factors that reduce the filterability: those that are caused by the clogging of the filtration surface due to the accumulation of trapped substances on the filtration surface and the clogging inside the ceramic membrane filtration layer. is there. Although jet cleaning is judged to be extremely effective for removing surface deposits, it is difficult to expect an effective effect on clogging. As effective countermeasures against clogging, ultrasonic irradiation and filtrate backwash are expected to be effective.

(1) Ultrasonic Cleaning With regard to ultrasonic irradiation, it is considered that in this test, dirt is removed by the cleaning effect caused by the cavitation generation condition, judging from the irradiation condition setting value. Ultrasonic irradiation under conditions that do not cause high frequency (MHz band) cavitation phenomenon is presumed to have little effect on removing fouling on the filtration surface, but it also promotes permeation and increases filtration rate by irradiation during filtration operation. You can expect it.

(2) Although it is presumed that the effect of clogging inside the jet washing filter layer is difficult to expect, it has been confirmed from the results of this test that the effect of removing the fouling on the filtration surface is extremely high, and recovery of the filtration speed is confirmed. Can be judged to be an extremely effective method. Even when applied to an actual machine, it is possible only by incorporating a spray nozzle, and we think that it can be easily designed.

(3) Filtration backwash Since the method is also used in the current porous tube type ceramic membrane, there is no problem in applying it to the disk type ceramic membrane. High pressure (about 0.5 MPa (Pe))
Although it has been confirmed that a large amount of backwashing is effective, there is a time loss associated with the backwashing. Therefore, the backwashing conditions that achieve the optimum filtration efficiency should be low pressure (about 0.3 MPa (Pe)) There is room for consideration as to the possibility of applying backwash.

5. Conclusion As methods for recovery of filtration speed and removal of fouling on the filtration surface in disk type ceramic membrane filtration, wiping / scraping, filtrate backwashing (high pressure (0.5 MPa (Pe))
It was judged that the following five items were effective: (or about) or low pressure (about 0.3 MPa (Pe) / short interval), jet cleaning, ultrasonic irradiation, and disk rotation (when used in combination with other methods). Considering practical application and practicality, it is considered effective to apply ultrasonic cleaning together with jet cleaning and reverse flow of filtrate + disk rotation.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[0063]

As described above, the solid-liquid separation device and the method of operating the same of the present invention have the following features. (1) Filtration can be performed while preventing clogging. (2) Ultrasonic waves do not adversely affect the ceramic or sintered metal filter plate (membrane filter). (3) By rotating the leaf type filter and changing the ultrasonic irradiation conditions, it is possible to provide a wide range of means for preventing clogging from physical peeling / removal of solid matter to chemical decomposition. . (4) When a filtrate as a product is obtained, irradiation conditions that do not cause a chemical change in the filtrate can be selected. Therefore, suspended substances in beverage raw material water, removal of cells in the fermentation production process, suspended substances in semiconductor polishing liquid, It is effective for filtration. (5) When a hydrophobic harmful substance such as an organic chlorine compound adheres to the suspended substance in water, the suspended substance is blocked on the filter plate by the filter according to the present invention, and the filtrate containing no harmful substance is removed. At the same time, the harmful substances on the filter plate can be decomposed by a chemical reaction by ultrasonic waves, which is effective for the treatment of wastewater containing hardly decomposable substances.

Therefore, the solid-liquid separation device and the method of operating the same according to the present invention can remove solids during filtration without interrupting the filtration step, thereby maintaining stable filtration performance for a long time. And has an excellent effect of being able to decompose organochlorine compounds such as PCB and dioxin contained in the solid content without using a chemical solution or a coagulant.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of a solid-liquid separation device of the present invention.

FIG. 2 is a schematic diagram of a membrane filter of the present invention.

FIG. 3 is an overall configuration diagram showing a second embodiment of the solid-liquid separation device of the present invention.

FIG. 4 is a schematic diagram of a test machine according to an embodiment of the present invention.

FIG. 5 is a relationship diagram between a permeation time and a filtration rate in city water filtration.

FIG. 6 is a relational diagram of permeation time and filtration rate in industrial water filtration.

FIG. 7 is a diagram showing the relationship between the filtration time and the permeation time by normal backwash.

FIG. 8 is a diagram showing the relationship between the permeation time by high-pressure backwash and the filtration rate.

FIG. 9 is a diagram showing the relationship between the filtration time and the permeation time of the filtrate backwashed.

FIG. 10 is a relationship diagram between the permeation time by jet cleaning and the filtration rate.

FIG. 11 is a schematic view of a conventional leaf filter.

FIG. 12 is another schematic view of a conventional leaf filter.

[Explanation of symbols]

1 filter leaf (leaf), 2 cake layer, 3 stock solution, 4 solid matter (cake), 5 filtrate, 6 rotation drive device, 7 scraper, 8 hopper, 10 solid-liquid separation device, 12 membrane filter, 12a filtration membrane layer, 12b through hole (center hole), 12c support, 14 hollow member, 14a spacer tube, 14b fixed rod, 16 liquid supply / discharge device,
16a treatment liquid tank, 18 ultrasonic cleaning device, 18a ultrasonic vibrator, 18b mounting plate, 18c resonance block,
20 Filter rotation device

Continued front page    (72) Inventor Takashi Imaoka             2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima             Harima Heavy Industries, Ltd. Tokyo No. 1 Factory F-term (reference) 4D006 GA06 GA07 HA83 HA93 JA19Z                       JA51Z KA41 KC03 KC19                       KE30R MC02 MC03X NA39                       PB08 PC11

Claims (5)

[Claims] 1. A plurality of membrane filters (1) having a filtration membrane layer (12a) formed on an outer surface thereof and having through holes (12b).
2) and a hollow member (14) that connects the plurality of membrane filters at a distance from each other and connects the through holes in a watertight manner.
A liquid supply / discharge device (1) for supplying the liquid to be treated to the outer surfaces of the plurality of membrane filters and for extracting the filtered liquid from the hollow holes of the hollow member (1
6) and an ultrasonic cleaning device (18) for cleaning the outer surface of the membrane filter with ultrasonic waves, a solid-liquid separation device. 2. The ultrasonic cleaning device (18) comprises about 20
It has an ultrasonic transducer (18a) capable of generating ultrasonic waves in the frequency range of kHz to about 600 kHz, whereby physical separation of solid matter adhered to the filtration surface due to shock waves due to cavitation generated in water, and / or Alternatively, the solid-liquid according to claim 1, characterized in that a water molecule is decomposed by a chemical reaction by cavitation to generate a hydroxyl group, and a solid substance attached is chemically decomposed by an oxidative decomposition reaction by a radical reaction. Separation device. 3. The membrane filter (12) is a ceramic plate or a sintered metal plate.
The solid-liquid separation device according to. 4. The membrane filter (12) has a through hole (1).
2b) is a disk shape having a central hole, the hollow member (14) is a hollow tube, and a plurality of membrane filters (12) are rotationally driven about the axis of the hollow member (14). A solid-liquid separation device according to claim 1, characterized in that it comprises a filter rotation device (20). 5. (A) A plurality of membrane filters (12) each having a filtration membrane layer (12a) formed on the outer surface and having through holes (12b) are connected to each other at intervals and each through hole is watertight. (B) The liquid to be treated is supplied to the outer surfaces of the plurality of membrane filters and the filtered liquid is extracted from the through holes of the hollow member, and (C) at the same time, continuously or intermittently outside the membrane filter. A method for cleaning a membrane separation device, which comprises cleaning the surface with ultrasonic waves.