JP7483198B2 - Solid-liquid separation equipment using filter aids - Google Patents

Description

The present invention relates to a solid-liquid separation device using a filter aid for separating and removing suspended solids contained in water to be treated, such as domestic wastewater or industrial wastewater.

2. Description of the Related Art Conventionally, as a solid-liquid separation device for separating and removing fine suspended solids from water to be treated, a vacuum dehydrator is known in which filtration is performed by stretching a filter cloth on the surface of a drum and pre-coating it with a filter aid.
Furthermore, Cited Document 1 discloses a technology in which magnetic powder having magnetic properties is added to the water to be treated, and contaminants in the water to be treated are adsorbed onto the magnetic particles through a chemical reaction or a coagulant to form magnetic flocs, which are then attached to the filtration surface on the outer periphery of a drum using a magnetic field generating device to perform solid-liquid separation.

JP 2002-66375 A

Generally, vacuum dehydrators precoated with fine particles such as diatomaceous earth as a filter aid are capable of precision filtration, and suspended solids in the filtered water are deposited on the precoat. When removing suspended solids using a scraping device, the surface layer of the precoat layer is scraped off at the same time as the suspended solids, increasing the amount of solids to be recovered and increasing the burden on post-processing of the solids. Furthermore, when the precoat layer becomes too thin to satisfy dewatering performance, it is necessary to stop the supply of water to be treated, add filter aid, and then re-form the precoat layer to the specified thickness.

The solid-liquid separation device described in Patent Document 1 imparts magnetism to the recovered solids so that they adhere to the filtration surface, but because magnetic powder is added to form magnetic flocs, the amount of recovered solids increases. Because the recovered solids are magnetic, they are difficult to handle when transported, and care must be taken depending on the disposal method.

The present invention provides a solid-liquid separation device that uses a filter aid that is precoated with a magnetic filter aid, separates the precoated filter medium from suspended solids when recovering solids, and reuses the filter aid as the precoated filter medium .

The present invention is a precoat type vacuum dehydrator in which a magnetic amorphous filter aid is laminated to a predetermined thickness on the surface of a filter cloth, and the liquid that can permeate the filter aid in the filtration / dehydration zone is sucked into the drum and discharged to the outside, and suspended matter that cannot permeate the filter aid is deposited on the surface of the filter aid. In this precoat type vacuum dehydrator, a peeling means is provided for continuously scraping off a part of the filter aid near the surface of the precoat layer together with the suspended matter captured by the precoat layer, a separation means for separating the suspended matter and the filter aid, a recovery means for recovering the filter aid, a return means for sending the filter aid to the lamination means of the vacuum dehydrator, and a lamination means for continuously re-laminating the filter aid returned to the lamination plate installed at a position between the peeling means and the filtration / dehydration zone, which is inclined downward toward the filter cloth stretched on the drum and has a tip that is the set thickness of the precoat layer, on the precoat layer that remains on the surface of the filter cloth. The precoated filter aid can be easily separated and recovered from the captured suspended matter, and returned to the solid-liquid separation device and re-laminated, making it possible to reuse the precoated filter aid.

The separation means is composed of a separation tank, a stirring device, and a magnetic roll. The magnetic roll is equipped with a belt wrapped around an upper roll and a lower roll, a magnetic plate attached to the inner surface of the belt, and a scraping device that peels the filter aid from the belt. This makes it easy to separate the filter aid and suspended matter from the recovered solids, and does not require effort in transporting or disposing of the suspended matter.

The present invention makes it possible to perform stable precision filtration operation by imparting magnetism to small particle size filter aids and pre-coating them. In addition, because the filter aids are made magnetic, the filter aids and suspended matter can be easily separated from the recovered solids, and the amount of recovered solids does not increase, making it easy to transport and dispose of the suspended matter. Furthermore, the filter aids can be reused as pre-coated filter media. When applied to a vacuum dehydrator, not only can the filter operation of the treated liquid be performed, but the separation, recovery, and reuse of the filter aids can also be continuously achieved.

FIG. 1 is a system diagram using a vacuum dehydrator according to the present invention. FIG. FIG. FIG.

FIG. 1 is a system diagram using a vacuum dehydrator according to the present invention, and FIG. 2 is a detailed view of the main parts of the vacuum dehydrator.
The apparatus comprises a stock solution tank 1 filled with stock solution, and a cylindrical drum 2 rotatably supported with its lower side immersed in the stock solution tank 1. The circumferential surface of the drum 2 is composed of a porous support bed 3, on which a filter cloth 4 is stretched. A suction pipe 5 is connected to the inside of the drum 2, and the pressure inside the drum 2 is reduced via the suction pipe 5 by a vacuum pump 6.

A precoat layer 8 is formed on the surface of the filter cloth 4 with a predetermined thickness using granular filter aid material 7, and the raw liquid supplied to the raw liquid tank 1 is sucked toward the drum 2 by the reduced pressure inside the drum 2. The liquid that can permeate the precoat layer 8 is sucked into the drum 2 and discharged to the outside, while the suspended matter that cannot permeate the precoat layer 8 is deposited on the surface of the precoat layer 8.

<Removal Means>
The drum 2 rotates in the direction of the arrow at a predetermined rotation speed, and the suspended solids deposited on the surface of the precoat layer 8 in the raw liquid tank 1 are separated by gravity under atmospheric pressure and then scraped off by the peeling means S1. At this time, a part of the filter aid 7 near the surface of the precoat layer 8 is scraped off by the peeling means S1 together with the suspended solids, and discharged into the downstream separation tank 10. In this embodiment, a scraper 9 is used as the peeling means S1, but other means may be used.

<Filtering aid>
The granular filter aid 7 forming the precoat layer 8 is made magnetic by known means such as the ferrite method, co-precipitation type magnetic loading method, polymer additive type magnetic loading method, magnetite magnetic loading method, surface adsorption type magnetic loading method, etc.

Various materials can be used as the filter aid 7, such as gypsum, perlite, activated carbon, beads, etc., but it is preferable to use porous diatomaceous earth with a particle size of 100 μm or less.

<Separation Means>
The suspended matter and a part of the filter aid 7 of the precoat layer 8 scraped off by the peeling means S1 are separated into the suspended matter and the filter aid 7 by the separating means S2 in the subsequent stage.

In this embodiment, the separation means S2 is composed of a separation tank 10, an agitator 11, and a magnetic roll 12. Specifically, the filter aid 7 and suspended matter discharged into the separation tank 10 are agitated by a known agitator 11, while the filter aid 7 is adsorbed by a magnetic roll 12 having a magnetic body and separated from the suspended matter.

Figure 3 is a vertical cross-sectional view of the magnetic roll 12, which is composed of an endless belt 15 wound around an upper roll 13 and a lower roll 14, and the belt 15 is rotated by driving at least one of the rolls. A magnetic plate 16 is attached to the inner surface of the belt 15 from the upper roll 13 to the lower roll 14, and the filter aid 7 is attracted to the outer surface of the belt 15 by the magnetic force of the magnetic plate 16. The filter aid 7 is transported to the upper roll 13 while being attracted to the outer surface of the belt 15, and is peeled off from the surface of the belt 15 by a scraping device 17. Magnetic force may be applied to each roll as necessary.

The stirring device 11 may be a known stirring device such as a paddle type stirring device that mechanically rotates an impeller or an air type stirring device that stirs by supplying air. Dilution water may be supplied during stirring as necessary.

The suspended solids are discharged to the outside through a discharge pipe provided below the separation tank 10. When the suspended solids are discharged to the outside, the filter aid 7 may be recovered by a magnetic body.

<Collection methods>
The filter aid 7 separated by the separation means S2 is transported to the recovery means S3. In this embodiment, the recovery means S3 is configured with a recovery tank 18, which stores the separated filter aid 7. The recovery tank 18 may be cleaned or sterilized as necessary. In this embodiment, an independently installed recovery tank 18 is used as the recovery means S3, but when the amount of recovered filter aid 7 is small, a chute connected to a transport pump 19 or the like may be used as the recovery tank 18.

<Return method>
The filter aid 7 recovered by the recovery means S3 is returned to the vacuum dehydrator by the return means S4. In this embodiment, the return means S4 is composed of a pump 19 and a return pipe 20. The filter aid 7 in the recovery tank 18 is pressure-fed by the pump 19 and transported via the return pipe 20. In this embodiment, the pump 19 and the return pipe 20 are used as the return means S4, but a known return means S4 such as a belt conveyor may also be used.

<Lamination Means>
The filter aid 7 is transported to the laminating means S5 via the return means S4. The laminating means S5 is provided in the vacuum dehydrator and continuously laminates the filter aid 7 on the precoat layer 8 of the vacuum dehydrator. Specifically, it is installed between the peeling means S1 (scraper 9) of the vacuum dehydrator and the filtration/dehydration zone, and re-laminates the precoat layer 8 that has become thinner than the set thickness when suspended solids are peeled off from the precoat layer 8 .

As shown in Figure 4, in this embodiment, the filter aid 7 is returned onto the laminate plate 21, and the filter aid 7 moves by its own weight on the inclined laminate plate 21, so that it is continuously re-adsorbed onto the precoat layer 8.

The laminate plate 21 is inclined downward toward the precoat layer 8, and is positioned so that its tip is at the set thickness of the precoat layer 8. The filter aid 7 separated and recovered by magnetic and suction forces is continuously attracted to the precoat layer 8, which has been thinned by the peeling means S1, and the thickness of the precoat layer 8 is adjusted at the tip of the laminate plate 21 so that it does not exceed the set thickness.

By constantly immersing a new precoat layer 8 in the raw solution, stable continuous filtration is possible, resulting in highly clear treated water.

In this embodiment, the magnetic filter aid 7 is used as the precoat layer 8 of a vacuum dehydrator, but it can also be used as a precoat material for solid-liquid separation devices such as candle filters, leaf filters, and filter presses.

The present invention can be applied to industries that require precision filtration to separate solids and liquids from treated water that contains small suspended solids, such as the food, pharmaceutical, chemical, and petroleum industries, and can reduce waste by reusing precoat materials, making it an environmentally friendly solid-liquid separation device.

7: filter aid 8: precoat layer 10: separation tank 11: agitator 12: magnetic roll 13: upper roll 14: lower roll 15: belt 16: magnetic plate 17: scraper S1: peeling means S2: separation means S3: recovery means S4: return means S5: lamination means

Claims (2)

In a precoat type vacuum dehydrator, a magnetic amorphous filter aid (7) is laminated to a predetermined thickness on the surface of a filter cloth , and in a filtration and dehydration zone, liquid that can permeate the filter aid (7) is sucked into a drum (2) and discharged to the outside, while suspended solids that cannot permeate the filter aid (7) are deposited on the surface of the filter aid (7) ,
A peeling means (S1) for continuously scraping off a part of the filter aid (7) near the surface of the precoat layer together with the suspended matter captured by the precoat layer (8);
A separation means (S2) for separating the suspended matter and the filter aid (7);
A recovery means (S3) for recovering the filter aid (7);
A return means (S4) for sending the filter aid (7) to a stacking means (S5) of a vacuum dehydrator;
and a laminating means (S5) for continuously re-laminating the filter aid (7) returned onto a laminating plate (21) disposed between the peeling means (S1) and the filtration/dehydration zone at a position inclined downward toward a filter cloth stretched on a drum so that its tip portion corresponds to a set thickness of the precoat layer (8), on the precoat layer (8) remaining on the surface of the filter cloth. The separating means (S2)
The apparatus is composed of a separation tank (10), a stirring device (11), and a magnetic roll (12),
The magnetic roll (12) is
A belt (15) wound around the upper roll (13) and the lower roll (14);
A magnetic plate (16) attached to the inner peripheral surface of the belt (15);
2. The vacuum dehydrator according to claim 1, further comprising a scraping device (17) for peeling off the filter aid (7) from the belt (15).

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