JP4873039B2 - Precoat type vacuum filtration device - Google Patents

Description

  The present invention relates to a precoat type vacuum filtration apparatus provided with a stock solution tank, a filter drum, and a scraper means, and a wastewater treatment system using the filtration apparatus.

  As shown in the flow sheet of FIG. 1, there is a demand for continuous treatment in a wastewater treatment system in which a flocculant is added to wastewater, solids contained in the wastewater are combined, and the solid diameter is separated after increasing the diameter. .

  In order to request this continuous treatment, a drum-type vacuum filtration device that captures solid components directly with a filter cloth without pre-coating is widely used (see Patent Document 1).

  However, a drum-type vacuum filtration device that directly captures solid components with a filter cloth has a problem in that it is difficult to stably obtain a high-clarity filtrate (treated water).

  Therefore, in order to obtain a filtrate with higher clarity, it is conceivable to use a precoat type vacuum filtration device equipped with a scraper device (see Patent Document 2).

  However, in a general-purpose scraper device, for example, when a coarse foreign matter such as a work or dust is mixed in water generated by a wet dust collector, the scraping blade of the scraper device or the precoat layer is damaged. For this reason, it was not suitable for the wastewater treatment in which such a foreign substance was mixed.

  Then, it is possible to use the scraping blade of the following structure as described in the claim of patent document 2. FIG.

“In a precoat filter characterized in that a scraper blade made of a 0.1 to 0.6 mm thin steel plate is elastically supported by a holding metal fitting on a holder of a scraper device mounted on a support table so as to face the cylindrical surface of the precoat filter. Cake scraper device. "
However, it has been found that the following problems occur when the scraping blade is thin and elastically held.

  This is because, when the moisture content of the solids formed on the drum (the layer of solids in the wastewater and the precoat layer) is not constant at the location where the scraping blade scrapes off, there is a difference in the abrasion amount of the scraping blade. This may cause a reduction in scraping performance, or may damage the precoat layer and cause a reduction in filtration performance.

  In addition, the precoat type vacuum filtration apparatus described in Patent Document 3 is a top feed type for supplying a stock solution from above the filter drum, and does not affect the patentability of the present invention.

Japanese Utility Model Publication No. 51-23099 Japanese Utility Model Publication No. 52-37916, JP-A-8-38818

It is a flow sheet which shows an example of the waste-water-treatment apparatus to which the vacuum filtration apparatus of this invention is applied. It is principle explanatory drawing of the precoat type vacuum filtration apparatus to which this invention is applied. It is the side model figure (A) and front model figure (B) for operation | movement description of the filter chamber division type filter drum applied to this invention. It is the whole scraper device applied to the present invention (A) and enlarged view (B) of the scraping blade holding part. It is the side model figure (A) and front model figure (B) of the vacuum filtration apparatus which arranged the paddle (fan turbbi type) rotary stirring blade between the filter drum applied to this invention, and a stock solution tank bottom part. It is the side model figure (A) and front model figure (B) of the vacuum filtration apparatus which similarly provided the rocking | swiveling stirring blade.

  In view of the above, the present invention can deal with waste water mixed with foreign matters etc. in the conventional precoat type vacuum filtration apparatus, and is less susceptible to wear even if the scraping blade is thin. It is an object of the present invention to improve the operation efficiency of the apparatus.

  As a result of diligent development efforts to solve the above problems, in the precoat vacuum filtration apparatus equipped with the scraper device described in Patent Document 2, if the drum configuration is the following configuration described in Patent Document 1, it is generated. The moisture content of the cake can be stabilized, the scraping resistance received by the scraping blade is stable and the wear amount of the scraping blade is not biased, and the vacuum filtration apparatus having the following configuration has been conceived. A reference numeral is attached for reference.

In a precoat type vacuum filtration apparatus comprising a stock solution tank 36, a filter drum 38, and a scraper means 46 (48),
The filter drum 38 has an inner cylinder portion 56 concentrically arranged with a predetermined gap inside the outer cylinder portion 58, and an annular space between the inner cylinder portion 56 and the outer cylinder portion 58 is equally divided by the partition plate 60. A plurality of filter chambers 62 are formed, and branch tubes 66 branched from a filtrate main pipe 64 that also serves as a rotating shaft are connected to each filter chamber 62 in the vicinity of the inner side surface in the rotation direction of the partition plate 60. In addition,
A stirring blade is disposed between the bottom wall of the stock solution tank 36 and the filter drum 38, and the stirring blade is an arcuate blade 106 that is arranged concentrically with the filter drum 38 and is capable of swinging movement. The upper surface of the bottom wall of the tank 36 is an arc surface along the lower surface side of the arcuate blade 106, and the stirring blade 106 is capable of swinging along the upper surface of the bottom wall of the stock solution tank 36. To do.

  One embodiment of the precoat type vacuum filtration apparatus (hereinafter simply referred to as “vacuum filtration apparatus”) of the present invention will be described as applied to a vacuum dewatering apparatus of a wastewater treatment apparatus (wastewater treatment system).

  FIG. 1 shows an example of a flow sheet of a wastewater treatment apparatus. This flow sheet assumes waste water treatment such as polishing waste water, acidic waste water, flexo ink waste water and the like.

  As a basic configuration, a waste liquid tank 12, a reaction tank 14, and a dehydrating device (vacuum filtration device) 16 are provided. The reaction tank 14 is provided with an alkaline liquid tank 18 and an inorganic flocculant tank 20.

In the present embodiment, an aqueous dispersion of slaked lime (Ca (OH) ₂ ) is stored in the alkaline liquid tank 18, and a sulfuric acid band (Al ₂ (SO ₄ ) ₃ .nH ₂ O is stored in the inorganic flocculant tank 20. ), An aqueous dispersion such as PAC (Al ₂ (OH) _n Cl _6-n ) is stored. Each of the tanks 18 and 20 includes a stirrer 22 and 22, and supply pipes 26 and 26 A including a supply pump are arranged between the tanks 18 and 20 and the reaction tank 14.

  The waste liquid tank 12 stores the polishing waste water and the like, and a waste liquid supply pipe 28 having a supply pump is disposed between the waste liquid tank 12 and the reaction tank 14.

  The reaction tank 14 includes a stirrer 22A. Between the bottom of the reaction tank 14 and the dehydrator 16, a raw solution supply pipe 31 having a supply pump for the raw solution (waste water containing floc: sludge) is disposed. Although not necessary, a supply pipe 30 for a polymer flocculant (chemical solution) is connected to the middle of the stock solution supply pipe 31.

  In the reaction tank 14 to which the waste liquid (for example, polishing waste water) is supplied, the pH of the waste liquid is adjusted to the alkali side with the alkaline liquid, and the fine particles in the waste liquid are negatively charged. Then, by supplying and stirring the inorganic flocculant, the positive charge in the flocculant reacts with the negative charge of the particles, and the particles stick to each other to form a floc (agglomerate).

  Then, waste water (sludge) containing floc is supplied to a dehydrating device (vacuum filtration device) 16. Here, by adding (supplying) the polymer flocculant to the sludge, the contained floc can be further increased in diameter and the floc strength (destructive strength) can be increased.

  As the polymer flocculant, an anionic one is used in the case of the waste liquid exemplified above. Examples of the anionic polymer flocculant include sodium alginate, CMC sodium salt, sodium polyacrylate, polyacrylamide partial hydrolysis salt, and the like.

  In this embodiment, the dewatering device 16 basically uses a precoat vacuum filtration device having the principle as shown in FIG.

  That is, a stock solution tank (filtration tank) 36 and a filter drum 38 disposed so that the lower side is immersed in the stock solution tank 36 are provided. A filtrate pipe 44 connects between the central rotating shaft side of the filter drum 38 and an airtight separation tank (decompression chamber) 42 provided with a vacuum pump 40.

The filter drum 38 can be rotated at a low speed (for example, 0.5 to 2 min ⁻¹ ) by forced driving, and a scraping blade 48 of a scraper means (scraper device) is disposed on the side facing the rotation direction of the filter drum 38. Has been. The scraper means allows the scraping blade 48 to be advanced at a predetermined speed, and continuously peels off the precoat layer 50 to which the cake 49 is adhered to constantly expose the surface of the new precoat layer 50. In this way, stable continuous filtration is possible, and treated water with high clarity can be obtained. As shown in the partially enlarged view of FIG. 2, the outer peripheral surface of the filter drum 38 is formed, for example, by stretching a filter cloth 54 on the upper surface of the outer cylinder portion 58 formed of a wire mesh or a perforated plate.

  In the present embodiment, the general-purpose filter drum 38 has the following configuration (see FIG. 3).

  Citation is made with some changes from the second column of Patent Document 1.

  A plurality of uniform filter chambers 62 are defined by a partition plate 60 between the inner cylinder portion 56 and the outer cylinder portion 58 of the filter drum 38 to be rotatable, and each filter chamber 62 has its partition plate 60 rotated. In the vicinity of the inner side surface in the direction, a branch pipe 66 branched from a filtrate main pipe 64 also serving as a rotating shaft is continued, and a stock solution tank (filter tank) 36 is placed so that the lower half of the filter drum 38 is located in the tank. It is installed.

  The filter drum 38 has an outer cylinder portion 58 formed of a wire mesh, and a filter cloth 54 as a support for the precoat layer 50 is stretched and fixed to the wire mesh. A filtrate main pipe 64 also serving as a rotation shaft provided at the center of both sides of the filter drum 38 is attached with a driving chain wheel 68 at an intermediate portion thereof, and an end thereof is connected to a vacuum device (not shown) via a hollow rotary joint. .

  What is formed in this way is that a pre-coating solution having a predetermined concentration is first supplied to the stock solution tank 36 from a pre-coating tank (not shown), and the filter drum 38 is rotated at a low speed and the vacuum device (vacuum pump 40) is driven at the same time Let At this time, a branch pipe 66 branched from the filtrate main pipe is continued in a plurality of uniform filter chambers 62 partitioned by the partition plate 60 between the inner cylinder part 56 and the outer cylinder part 58.

  For this reason, when there is no undiluted solution (precoat solution or reaction solution) in the tank, the pressure is evenly reduced and an equal amount of air is sucked through the outer cylinder portion 58.

  Next, as shown in the figure, the lower half of the filter drum 38 consisting of six filter chambers 62 that rotate clockwise in the direction of the arrow is positioned in the tank, and the stock solution (precoat liquid or reaction liquid) is supplied into the tank. In this case, the suction action is as follows.

  The filter chamber 62 that has reached the lower right position A corresponding to the filtration zone adsorbs the dispersoids in the stock solution on the surface and sucks the filtrate into the filter chamber 62. At this time, since the filtrate has not yet reached the suction port portion of the branch pipe 66, the filtrate sucked into the filter chamber 62 is not sent to the filtrate main pipe 64.

  In this way, the filter drum 38 is gradually rotated to reach the lower left position B, and the filtrate sucked into the filter chamber 62b reaches the suction port of the branch pipe 66. Therefore, the branch pipe 66 and the filtrate main pipe. After passing through 64, the filtrate is gradually sucked and discharged, and a suction force is applied to the surface of the outer cylinder portion 58 of the filter chamber 62 to the extent that the adsorbed cake is not peeled off at the lower left position.

  Next, in the filter chamber 62 that has been rotated to the left position C, the internal filtrate reaches the suction portion of the branch pipe 66 as in the lower left position B. Therefore, the filtrate is further discharged through the branch pipe 66 and the filtrate main pipe 64, and the upper half of the surface of the filter chamber 62 communicates with the atmosphere through the cake adsorbed thereto. At this time, since the suction port portion of the branch pipe 66 is located in the filtrate, the amount of air passing through the upper half is very small and does not adversely affect the suction force with respect to the other filter chambers 62.

  Further, the filter chamber 62 rotated to the upper left position D, like the left position C, functions as a drying zone by the moisture in the cake being sucked into the filter chamber 62 at the left position C and the upper left position D. become. For this reason, the amount of filtrate in the filter chamber 62 is also reduced.

  Next, in the filter chamber 62 rotated to the upper right position E, the inner filtrate flows in the rotational direction, the suction port of the branch pipe 66 is released, and the amount of air sucked from the surface of the filter chamber 62 slightly increases. To do. At this time, the filtrate remaining in the filter chamber 62 is in the lower part of the surface of the filter chamber 62. For this reason, the vacuum balance with the lower right position A and the lower left position B corresponding to the filtration zone is improved without adversely affecting the suction force of at least the other filter chamber 62 on the surface of the filter chamber 62e that directly sucks air. is doing. When the filter chamber 62 is rotated to the upper right position E, the tip of the scraping blade 48 faces the outer periphery of the filter chamber 62 to dry in the drying zone consisting of the left position C and the upper left position D. The precoat layer to which the prepared cake is attached can be peeled off.

  Next, when the filter chamber 62 is rotated to the right position F, the filter chamber 62 acts in the same manner as the upper right position E. At this time, the lower part of the filter chamber 62 is gradually immersed in the stock solution in the filter tank, so that the amount of air sucked from the surface is further reduced than the amount of air sucked in the upper right position E, and other filter chambers. There is almost no adverse effect on the suction of 62.

  Through such a process, the filter drum 38 continues to rotate, so that the left position C and the upper left position D that are drying zones, the upper right position E that is a peeling zone, and the lower right position A that falls between the peeling zone and the filtration zone. In addition, the vacuum efficiency at the lower left position B is extremely high, and an efficient filtration operation can be continuously performed without a switching valve.

  Next, details of the scraper means (scraper device) 46 will be described (see FIG. 4).

  Hereinafter, the following changes are made from the second to third columns of Patent Document 2 with editorial changes.

  A scraper device 46 that can move toward the precoat layer 50 formed on the outer peripheral surface of the filter drum 38 is attached to the support stand 74 provided on the machine frame 72 at an angle.

  A screw shaft 76 is pivotally supported by a bearing attached to a support base, and the screw shaft 76 is attached to be inclined with respect to the precoat layer 50, and a holder 78 is fixed to the tip of the screw shaft 76 at a right angle. . A notch 80 is provided at one end of the holder 78, and a scraper blade 48 made of a thin steel plate having a razor blade thickness of 1 mm or less (preferably 0.1 to 0.6 mm) is placed on the notch 80. The entire surface of the scraping blade 48 is held on the surface of the notch 80 by a presser fitting 82 made of a mountain-shaped elastic thin plate having a protrusion 81 for pressing it. The presser fitting 82 can be tightened by tightening a fastening bolt 84 so that the scraping blade 48 is elastically supported by the tip of the presser fitting 82 and the tip of the projection 87. The male screw portion 86 of the screw shaft 76 is screwed into a sleeve 90 having a female screw 88. The outer diameter portion of the sleeve 90 is keyed to the worm wheel 92. The worm wheel 92 meshes with a worm 96 having a worm shaft 94. The worm 96 and the worm wheel 92 are accommodated in a gear case 98 integrated with the bearing. Further, the worm shaft 94 can be engaged with and disengaged from the worm wheel 92 by an engagement / disengagement device (not shown). Further, a stopper collar 100 that prevents the screw shaft 76 from moving forward is attached to the end of the screw shaft 76, and a handle 99 is attached to a sleeve 90 that is fitted to the screw shaft 76.

  In this configuration, when the worm shaft 94 is rotated and the worm 96 is rotated, the screw shaft 76 gradually advances toward the precoat layer 50 and the scraping blade in which the precoat layer to which the cake adheres is inclined. It is possible to cut thinly with 48 cutting edges. At this time, the cutting edge portion of the scraping blade 48 is worn, but since the thickness of the scraping blade 48 is as thin as 0.1 to 0.6 mm, a flat portion as seen in the case of a thick blade even if the cutting edge portion is worn. It will never be a cutting edge. For this reason, the frictional resistance acting on the cutting edge during scraping of the cake is less than in the case of the thick blade, and the cutting action of the cake layer does not change much.

  Therefore, the precoat layer exposed by scraping the cake does not cause striped clogging, and the scraping blade 48 attached to the holder 78 can withstand long-term use.

  Further, the scraping blade 48 is elastically supported by a presser fitting 82 made of an elastic thin plate. Therefore, even when the scraping blade 48 is mounted on the holder 78 as a whole and a hard lump of foreign matter is present in the cake, the tip of the scraping blade 48 is slightly deformed by the elastic action of the presser fitting 82. Thus, the foreign matter can be overcome or scooped out, and the blade tip does not spill due to the impact applied to the tip.

  As described above, the thickness of the scraping blade 48 is preferably 0.1 to 0.6 mm, but depending on the material of the scraping blade 48, it can be in the range of 0.05 to 1 mm.

  Furthermore, in the present embodiment, the filter drum 38 can filter the suction filtration pressure with a stable suction pressure without using the switching valve as described above, so that the moisture content of the cake adhering to the precoat layer is stabilized. ing. Therefore, the undulation (variation) of the surface strength of the cake adhesion precoat layer at the scraping position is small. For this reason, the scraping blade is cut smoothly in the normal state where it does not interfere with foreign matter, and wear of the scraping blade occurs evenly regardless of the position of the drum. No reduction in filtration performance due to layer breakage.

  A more desirable form of the present embodiment is that, in the above configuration, a stirring blade (stirring means) is disposed between the bottom wall of the stock solution tank 36 and the filter drum 38.

  This stirring means is installed in the filtration tank (stock solution tank) 36 in order to prevent sedimentation of flocs. The accumulation of flocs causes a reduction in filtration efficiency.

  As the stirring means, a horizontal rotation stirring type (paddle type) (FIG. 5), a swing stirring type (cradle type) (FIG. 6), and the like are conceivable.

  In the case of the horizontal rotary stirring type, it is necessary to increase the rotational speed of the paddle (rotary blade) 102 to prevent sedimentation of flocs. However, when the number of rotations is increased, the floc is destroyed and the floc diameter is reduced, so that the particle size of the filter aid for forming the precoat layer for capturing the floc cannot be increased. If the particle size of the filter aid can be increased, the particle gap in the precoat layer increases and the filtration rate increases. Incidentally, the general-purpose particle size of the conventional filter aid (for example, diatomaceous earth) was about 40 μm.

  Moreover, it is necessary to provide the bearing part of the rotating shaft 104 in the stock solution tank 36, and it is necessary to set it as a liquid seal structure.

  In contrast to the horizontal rotation stirring method, the swing stirring method has a structure in which the driving shaft of the swing lever is provided outside the liquid (the rotation shaft portion of the filter drum). For this reason, a seal structure for supporting the shaft in the stock solution tank 36 is unnecessary. Further, by gently rocking the stirring member along the bottom of the stock solution tank, it is easy to prevent sedimentation without destroying the floc.

  Here, the shape of the oscillating stirring blade may be a rod body, an angle body, or a band plate body that oscillates along the arc-shaped bottom portion of the stock solution tank 36. Desirably, the arc stirring blade 106 is a planar frame body or a planar porous body.

  At this time, the gap between the arc-shaped stirring blade 106 and the bottom surface of the stirring tank is, for example, 1 to 25 mm, depending on the size of the formed floc.

  The shape of the arc stirring blade 106 is not particularly limited as long as it is arcuate, and may be a perforated plate, but a pair of arcuate plates connected by a bar, an angle, or a slat arranged at equal intervals. The stirring effect is easy to obtain, which is desirable.

  The arc-shaped stirring blade 106 is driven to swing using a general-purpose reciprocating mechanism connected to a prime mover (not shown).

  Next, the usage aspect of the vacuum filtration apparatus provided with the said stirring apparatus is demonstrated.

1) Precoat operation The filter aid dispersion is pumped to the stock solution tank 36. In addition, it does not specifically limit as a filter aid, For example, diatomaceous earth, perlite, etc. can be used.

Then, the filter drum 38 is rotated at a low speed (for example, 1 min ⁻¹ ) and vacuumed (for example, 40 kPa), and the arc-shaped stirring blade 106 is further oscillated (reciprocated). The reciprocating motion cycle at this time is 20 to 50 Hz.

  At this time, the tip of the scraping blade 48 of the scraper device is kept stationary at a position away from the outer peripheral surface of the filter drum 38 by the set thickness of the precoat layer 50.

  By reciprocatingly swinging the arc-shaped stirring blade 106, even a large particle size filter aid does not accumulate at the bottom of the stock solution tank 36. Further, as described above, a high suction pressure acts on the filter cloth surface of the filter drum 38 while being immersed in the precoat liquid. For this reason, a filter aid having a large particle size is efficiently attached to the filter drum 38, so that the precoat layer is efficiently formed. Here, for example, in the case of diatomaceous earth, one having a particle diameter of 40 to 80 μm is used.

  In order to prevent cracks, fresh water is supplied during pre-coating.

2) Aggregation operation The waste liquid is supplied from the waste liquid tank 12 to the aggregation reaction tank 14 with a supply pump until it receives the L position signal of the level meter of the aggregation reaction tank 14 and reaches the H position.

  Simultaneously, alkaline liquid such as slaked lime is pumped to the reaction tank 14 from the alkaline liquid tank 18 to the reaction tank 14. The supply of the alkaline liquid is performed while stirring until the waste liquid in the reaction tank 14 becomes predetermined alkaline with the equipped pH meter.

  At the same time, the inorganic flocculant liquid is pumped into the reaction tank 14 from the flocculant tank 20 with stirring until the pH reaches a predetermined pH (for example, 6.5 to 7.5) with the equipped pH meter.

  After supplying the flocculant, stirring may be stopped and the generated flocs may be allowed to settle at the bottom of the reaction tank 14. However, the flocs are continuously generated in the stock solution tank 36 of the vacuum filtration device 16 simultaneously. You may supply.

3) Filtration operation The stock solution (sludge) is supplied from the reaction tank 14 to the stock solution tank 36 until it receives the signal at the L position equipped in the stock solution tank 36 and becomes the H position.

  At this time, the filter drum 38 vacuum-sucks each filter chamber 62 and rotates it at a low speed. Further, the scraping blade 48 of the scraper device 46 is located at the surface position of the precoat layer 50 and moves forward at a predetermined speed. The forward speed at this time is 0.05 to 0.15 mm / min.

  It is desirable to supply the anionic polymer flocculant in the middle of the stock solution supply pipe 31. For this reason, the floc grows up to 1-5 mm. The amount of the polymer flocculant added is, for example, 1.0 to 5.0 mg / L for the waste liquid having an SS concentration after aggregation of up to 4000 mg / L.

  If the addition amount of the polymer flocculant is excessive, the filtration resistance increases due to the viscosity of the excess polymer flocculant. If the amount is too small, the addition effect by the polymer flocculant, the increase in floc strength and the filter aid. It becomes difficult to make the diameter larger.

  Even when the flocs are grown, the flocs do not settle and the flocs are hardly destroyed because they are gently swirled and stirred by the cradle type arcuate stirring blade 106. In this case, the reciprocating cycle is 20 to 50 Hz.

  As described above, since the suction pressure in each filter chamber 62 is maintained at a degree of vacuum sufficient for filtration, flocs are well captured by the precoat layer to form a cake.

  In order to confirm the effect of the present invention, examples carried out together with comparative examples will be described.

Filtration processing set time: 8h
<Experiment method>
The treatment target was barrel polishing wastewater generated by wet fluid barrel polishing (abrasive: alumina) of iron-based metal parts: 4 m ³ (ss concentration: 1200 mg).

  The specifications of the vacuum filtration apparatus were as follows.

Stock solution tank: width 830mm x length 524mm x height 426mm, bottom R: 558mm
Filter drum ・ ・ ・ Size: 600Φ × 300L, Filtration area: 0.5m ² , Rotation speed: 1min ^-1
Paddle type: Two plate blades (length: 103 mm x diameter: 110 mm) are alternately attached to the rotating shaft at an angle of 90 °.

Cradle type: Opening angle α: 60 ° arc-shaped plates connected by 4 angles (40mm x 40mm x 5mm) at the middle two ends (length (arc-side projection) 600mm x width 432mm ). Gap with stock solution tank bottom: 20mm
(1) Pretreatment of waste water 1) Add slaked lime while stirring the polishing waste water (waste liquid) from the waste liquid tank 12 to the reaction tank 14 until the polishing water becomes pH: 9-10.

  2) Further, while continuing stirring, a sulfuric acid band as an inorganic flocculant is added until neutrality.

(2) Pretreatment of vacuum filtration apparatus 1) 0.15 m ^{3 of} water and filter aids (diatomaceous earth: FA2000 or FA6000 manufactured by Shinto Blator Co., Ltd.) having respective particle sizes shown in Table 1 are placed in the stock solution tank 36 (FA2000). : 10 kg, FA6000: 7 kg).

2) By operating the vacuum pump 40 while rotating the filter drum 38 (1 min ⁻¹ ) (suction pressure: 300 mmHg: 39.6 kPa), a precoat layer (filter aid layer: 50 mm) is formed on the drum peripheral surface. . At this time, the stirring device was also operated (paddle type: 39 min ⁻¹ , cradle type: 30 Hz).

(3) Filtration treatment 1) Sludge generated in the reaction tank 14 is supplied from the reaction tank 14 to the stock solution tank 36 via the stock solution supply pipe 31 by operating the stock solution pump. In Example 3, 20 g of a polymer flocculant (Hyperclear C-30 manufactured by Shinto Brater Co., Ltd.) is added in the middle of the stock solution supply pipe 31.

2) Vacuum filtration is performed by operating the vacuum pump 40 (suction pressure: 300 mmHg: 39.6 kPa) while rotating the filter drum 38 at a low speed (1 min ⁻¹ ).

At this time, the scraper feed motor is operated to advance the scraping blade (scraper) 48 (feed speed: 0.07 mm · min ⁻¹ ). At the same time, the paddle 102 or the oscillating stirring blade 106 is operated (paddle type: 39 min ⁻¹ , cradle type: 30 Hz).

  Moreover, the vacuum filtration apparatus used by each Example and the comparative example shall be shown in Table 1 about the filter drum structure, scraping blade board thickness, and stirring means in the apparatus for experiment made in-house.

(4) Test results Table 1 shows the test results of the examples, comparative examples, and reference examples.

  From Table 1, it was confirmed that each example of the desirable mode of the present invention required a short filtration completion time.

  The reference example was not able to be filtered in this example because no agitation means was provided, but can be implemented if the waste liquid is not sedimentable.

12 Waste liquid tank 14 Reaction tank 16 Dehydration device (vacuum filtration device)
36 Stock solution tank 38 Filter drum 48 Scraping blade 50 Precoat layer 54 Filter cloth 56 Filter drum inner cylinder portion 58 Filter drum outer cylinder portion 60 Filter chamber partition plate 62 Divided filter chamber 102 Paddle type stirring blade 106 Arc plate stirring Wings

Claims (4)

In a precoat type vacuum filtration apparatus equipped with a stock solution tank, a filter drum, and a scraper means,
The filter drum has an inner cylinder portion concentrically arranged with a predetermined gap inside the outer cylinder portion, and a plurality of annular spaces between the inner cylinder portion and the outer cylinder portion are equally divided by a partition plate. Each of the filter chambers is connected to a branch pipe branched from a filtrate main pipe that also serves as a rotating shaft in the vicinity of the inner side surface in the rotation direction of the partition plate.
The scraper means is configured such that a scraping blade having a tip thickness of less than 1 mm is elastically pressed and supported so as to be able to escape on the tip side on a holder that can be advanced with respect to the filtration surface of the filter drum .
A stirring blade is disposed between the bottom wall of the stock solution tank and the filter drum, and the stirring blade is an arcuate blade that is arranged concentrically with the filter drum and is capable of swinging movement. The upper surface of the bottom wall of the tank is an arc surface along the lower surface side of the arc-shaped wing,
The stirring blade is capable of swinging along the upper surface of the bottom wall of the stock solution tank.
A precoat type vacuum filtration device characterized by the above. 2. The precoat vacuum filtration apparatus according to claim 1, wherein the precoat layer formed on the outer peripheral surface of the filter drum is made of a filter aid having an average particle diameter of 40 to 80 [mu] m. In a wastewater treatment system comprising a reaction flocculation apparatus for adding a chemical to wastewater to form a floc, and a filtration separation apparatus for filtering and separating the floc-containing liquid from the reaction flocculation apparatus into cake and clarified water,
The wastewater treatment system, wherein the filtration / separation device is the precoat vacuum filtration device according to claim 1 or 2 . 4. The wastewater treatment system according to claim 3 , further comprising a polymer flocculant supply means in the middle of a raw liquid supply pipe from a reaction tank of the reaction coagulation apparatus to a raw liquid tank of the precoat type vacuum filtration apparatus.

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