JP2010094568A - Device for washing deposited sand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for washing deposited sand capable of attaining a high recovery rate of soil and sand contained in dirty water in a sand sedimentation pond as well as a high removal rate of organic substances adhering to the soil and sand at the same time. <P>SOLUTION: Organic substances adhering to soil and sand comprising microparticles are efficiently washed off by ejecting a mixture of water and air comprising microbubbles into a washing tank 13. In addition, the organic substances and the soil/sand are efficiently and gravitationally separated by virtue of the difference of the specific gravities thereof by causing the dirty water to flow into a parallel spiral flow-path 14a formed between conical spiral plates 14 because a spiral separator 15 equipped with the washing tank 13 is incorporated in the device 10 for washing deposited sand. As a result, a high recovery rate of the soil and sand contained in the dirty water as well as a high removal rate of the organic substances adhering to the soil and sand are attained at the same time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sand settling apparatus, and more particularly, to a sand settling apparatus that cleans sand settling from a sand settling basin.

In a sewage treatment plant where sewage and rainwater are introduced, sediment and sand, etc. in the sewage are settled and separated in a sand basin, and the sand that has settled on the bottom of the pond is pumped to a sand-washing tank, where We are cleaning. Generally, sewage contains 0.0001 to 0.005 volume% of sand.
In the conventional sand washing apparatus, an aeration nozzle and a washing water nozzle are provided at the bottom of the sand washing tank and the sand washing tank, and a transfer means for discharging the washed sand is provided at the bottom of the sand washing tank. It is a configuration. First, in the sand washing tank, washing water is allowed to flow while the sand is strongly aerated to wash away organic matter (rotted organic matter) that is a base of malodor adhering to the sand. Organic matter with a low specific gravity does not settle and is returned to the sand basin along with the overflow water (separated water) of the sand wash tank. On the other hand, the earth and sand (washed sand) settled at the bottom of the sand washing tank is collected by a collection conveyor and a basket and transported to a landfill disposal site. The collection rate of earth and sand in the sand washing tank is as low as about 40%.
In addition, organic matter such as sediment and earth and sand accumulate in the pipe facilities of the sewage pipes and pump stations before the sewage is introduced into the sewage treatment plant. Since these deposits impede water flow and generate bad odors, they are regularly removed as dredged sand, and the dredged sand is washed in a sand washing tank in the same manner as the above-mentioned sedimentation. Also in this case, the collection rate of earth and sand in the sand washing tank is low.

  By the way, in the sewage treatment plant in the city, since sludge is concentrated, before the sludge in the first sedimentation basin and final sedimentation basin is sent, sediment with large specific gravity does not accumulate in the mud pipe. Pretreatment is carried out to separate the sediment from sludge using a liquid cyclone in advance. Or in a general sewage treatment plant, in order to prevent wear and blockage of the sludge concentrator, a pretreatment for separating sand from sludge may be performed in the same manner. The sand settling separated here is often washed in a sand washing tank because it contains a lot of organic matter such as paper fiber. However, similarly to the above, the recovery rate of earth and sand in the sand washing tank is low, and depending on the particle size of the separated sand, it is very low as 20 to 10% or less. Therefore, in the present situation, sand with small particles in the sludge is difficult to take out of the system and is circulating in the sewage treatment plant.

On the other hand, in recent landfills, there is a tendency to reduce organic matter as landfills for the purpose of securing the remaining years of landfills and suppressing the generation of methane gas, which is a warming gas. Therefore, in many cases, the organic matter content (heat loss) of sand that can be accepted is defined as 10 to 15% or less, and if the amount of organic matter is large, it cannot be accepted at a landfill. For example, some cities stipulate that the acceptable organic content (heat loss) of sand is 15% or less. For this reason, it is necessary to thoroughly wash the sedimentation in the sewage treatment plant.
However, with the conventional sand settling device that aims to remove the organic matter (septic organic matter) that is the basis of malodor, it is not easy to reduce the organic content so far. The earth and sand also almost flow out, and it is difficult to achieve both the earth and sand recovery rate and the organic matter removal. For this reason, development of the new sand-washing apparatus which can perform this compatibility was requested | required.

The present inventors instead of using a conventional sand settling apparatus, spraying mixed water containing fine bubbles into a washing tank, thereby removing fine particles of fine sand, silt, and clay contained in the settling sand by an organic material. It was found that the coarse bubbles can float and flow out easily when these fine bubbles adhere to the organic matter. In addition, by adopting an inclined plate type sandwashing separator having an inclined separating plate in this washing tank, the entire washing tank is agitated by fine bubbles to prevent the earth and sand from rising to the liquid level, and between the inclined plates. It was found that by flowing sewage into parallel gaps, organic matter and earth and sand can be efficiently separated by gravity using the difference in specific gravity, and many earth and sand can be captured and recovered. As a result, the inventors have found that the above-described problems can be solved, and have completed the present invention.
Thus, an object of the present invention is to provide a sand-washing apparatus capable of simultaneously obtaining a high recovery rate of earth and sand contained in sewage and a high removal rate of organic substances contained in the sand.

  The invention described in claim 1 has a washing tank for introducing sewage containing organic matter and earth and sand transferred from the bottom of the sand basin by a sand settling machine, and is housed in the washing tank and includes a parallel gap between the inclined plates. An inclined plate type sandwashing separator that gravity separates the organic matter and the earth and sand from the wastewater that has flowed into the wastewater, and a mixed water containing fine bubbles in the washing tank is ejected from the nozzle. An air-mixed water producing machine for washing the earth and sand, and a earth and sand collection conveyor for collecting the earth and sand washed from the lower part of the washing tank, wherein the separation liquid containing the organic matter floating near the liquid surface of the washing tank It is a sand washing device characterized by providing a pipeline to return to the pond.

According to invention of Claim 1, the organic substance contained in earth and sand is washed away by ejecting the mixed water containing a fine bubble in a washing tank from a nozzle. In addition, the inclined plate group shortens the settling distance of the separated sand, drops the separated earth and sand along the inclined plate, and the organic matter attached with fine bubbles rises along the lower surface of the inclined plate, thereby flowing upward. Sediment does not mix with sewage after washing, and sedimentation speed of sediment can be increased. Since the mixed water contains fine bubbles, it is possible to dissolve fine sand, silt, clay and organic matter in the earth and sand by shearing force due to the buoyancy of the bubbles, and by attaching fine bubbles to the organic matter, the floatability of the organic matter can be improved. It is possible to enhance the separability between the organic matter and the earth and sand in the inclined plate type sedimentation separator. In addition, by blowing fine bubbles into the washing tank as mixed water, particularly from the nozzle toward the bottom of the tank, preferably toward the bottom of the tank, fibrous organic matter such as paper fibers and hair that have settled together with earth and sand, or coarse vegetable waste or The residue such as tobacco filters can be washed again and washed out.
In addition, an inclined plate type sandwashing separator is adopted, so when sewage flows into the parallel gap between the inclined plates, the separation time between organic matter and earth and sand can be shortened, and gravity separation can be performed efficiently using the specific gravity difference. it can. Thereby, the high recovery rate of the earth and sand contained in sewage and the high removal rate of the organic substance contained in earth and sand can be obtained simultaneously.

As the shape of the cleaning tank, for example, a rectangular shape or a circular shape in a plan view, a hopper shape in which a cross-sectional area is gradually reduced toward the bottom, and the like can be adopted. In the case of a hopper type washing tank, the inclination angle of the bottom is 45 ° or more, preferably 60 ° or more and less than 90 ° with respect to the horizontal. Below 45 °, there is a high probability of cleaning sand accumulation. However, when a mechanical sand collecting device is provided, the slant angle is 10 ° or more, preferably 20 ° or more and less than 90 ° with respect to the horizontal, because it is scraped by the sand collecting device.
Sewage refers to, for example, domestic wastewater that flows into sewage, sand collected from rainwater in a sand basin, dredged sludge accumulated in pipeline facilities, separated sand separated from sediment pond sludge, human waste, septic tank sludge, etc., construction site And wastewater including dredged material such as rivers, bays and lakes.
Sedimentation is earth and sand settled and captured in a sand basin at a sewage treatment plant. In addition to minerals such as gravel, sand, silt, and clay, paper sediments such as paper fibers, wood chips, vegetable scraps, tobacco filters, etc. The thing containing various kinds of organic matter. The main inorganic substances are sand and gravel, and the particle size is mainly about 200 μm to 10 mm, but fine sand and silt of 200 μm or less are also included.

  As the sand settling machine, for example, a sand feeding pump type sand set feeding machine that pumps the set sand collected by a bucket conveyor can be adopted. In addition, a mixed air jet pump type sand settling machine or the like that sucks and transfers sand settling using pressurized water and air may be used.

As the inclined plate type sandwashing separator, for example, an inclined plate group in which inclined plates in which a plurality of inclined plates are arranged in parallel in a state of being separated from each other in a cleaning tank can be employed.
Further, a spiral separator in which a conical spiral plate in which a spiral flow path is formed in a cylindrical tank is rotated by a rotating means around a rotation axis whose axis is vertical may be used. Among these, the spiral separator is preferable because it rotates and can receive upward flow and fine bubbles uniformly in the entire inclined plate. In addition, the inclined plate group can be loaded with a larger amount of treated water as more inclined plates are stacked. However, in the general inclined plate group, the folded portion of the inclined plate increases as they are stacked, and the floating organic matter separated from the folded portion and the settled earth and sand partially mix, or the large residue (organic matter) is blocked. There is something. In this respect as well, the spiral separator in which the spiral flow path without folds is formed has no large clogging (organic matter) clogging, sedimentary sediment is collected on the outer periphery side, and floating organic matter is collected on the inner cylinder side. Since the separated organic substance and earth and sand do not mix again, it is preferable.
The angle of the inclined plate is 45 ° or more and less than 90 °, preferably around 60 ° with respect to the horizontal. Below 45 °, there is a high probability of cleaning sand accumulation.
The interval between the inclined plate and the inclined plate in the inclined plate group is 75 to 150 mm. If the interval is smaller than 75 mm, there is a high possibility that blockage due to large residue and soaring of fine sand and silt captured on the upper surface of the inclined plate will occur.

As an example of the inclined plate of the inclined plate group, a large number of inclined plates, such as flat plates and corrugated plates, are inclined at the above-mentioned angle with respect to the horizontal, and through a plurality of vertically long connecting frames so as to follow the direction in which sewage flows. Thus, it is possible to employ a structure in which the inclined plates are arranged in parallel with a certain distance therebetween. The inclined plate group is positioned such that its upper edge is lower than the level of the sewage.
The inclined plate group is placed in a frame made of SUS304 using, for example, a hanging metal fitting, and is configured to be easily attached and detached.

The spiral separator has at least one conical spiral plate having a vertically extending spiral axis, and the conical spiral plate has at least one spiral flow between its axially facing surfaces. The thing in which the path is formed can be employ | adopted. Preferably, a plurality of, for example, 20 coaxial conical spiral plates are provided, and more preferably, a plurality of spiral flow paths are formed in a multiple spiral shape.
The conical spiral plate may draw a left-handed spiral or a right-handed spiral.

One or more conical spiral plates may be accommodated in a cylindrical washing tank. The conical spiral plate is rotated to induce an axial upward flow of sewage containing sedimentation along the spiral flow path in the washing tank.
The cleaning tank may be a cylindrical tank (including a tapered hopper on the lower side) or another arbitrary cylindrical tank.
A preferred spiral separator has a rotating shaft on which a conical spiral plate is disposed in a cylindrical cleaning tank, and one or a plurality of conical spiral plates coaxial with the cleaning tank are attached. In this case, the spiral separator has a diameter substantially equal to that of the cleaning tank. By disposing a processing liquid inlet and a processed liquid outlet in the cleaning tank at positions spaced apart in the direction of the rotation axis, sewage containing sedimentation along the conical spiral channel in the cleaning tank. An axial upward flow can be induced. The conical spiral plate is rotated about the rotation axis.

Here, the vertical speed at which the liquid to be treated is pumped by rotation of the conical spiral plate (B: rotation) with respect to the vertical speed at which the liquid to be treated ascends in the cleaning tank (A: rising speed within the inclined plate group) The speed at which (speed x pitch) is equal is defined as No Swirl Speed (NSS), and the B / A ratio is the NSS ratio. The rotational speed of the conical spiral plate is set so that the NSS ratio is between 0.5 and 4. When the NSS ratio is less than 0.5, flow resistance is generated by the inclined plate, the upward flow is disturbed, the inflow becomes uneven, or a part of the processing target is in the gap between the outer peripheral inclined plate group and the outer wall. Separation efficiency decreases due to the flow of liquid. On the other hand, when the NSS ratio exceeds 4, the inside of the washing tank is disturbed by the rotation of the conical spiral plate, and the separation efficiency is also lowered. Preferred NSS ratio is 1 to 2.5, No
By causing a slightly faster pumping effect than Swirl Speed (NSS), the liquid to be treated can be drawn into the inclined plate group without disturbing the flow, and the separation effect can be enhanced most. In addition, since the separation effect varies greatly depending on the pitch and the amount of treated water, it cannot be defined by the rotation speed of the rotating shaft.
As an air-mixed water production machine, for example, the one that has a pressure pump for the first sedimentation basin overflow treated water or sewage treated water (reused water) in the sewage treatment plant and a compressor that generates compressed air should be adopted. Can do. For example, in the case of a cleaning tank having a hopper portion, the mixed water injection nozzle is preferably arranged on the inner surface of the hopper portion with the injection nozzle port facing downward from the horizontal. In addition, you may install in the introductory pipe | tube which introduces the sewage containing sedimentation into an inclined plate type sand-washing separator with the injection nozzle port directed in the direction of introducing the sewage.

The size of the fine bubbles is, for example, 1 mm or less, and 0.01 to 0.5 mm for enhancing the cleaning effect. If it exceeds 1 mm, bubbles are less likely to be attached to the organic matter, and the rising speed of the bubbles is increased to cause upward drift, thereby reducing the separation efficiency and the sediment recovery rate.
As the earth and sand recovery conveyor, for example, a screw conveyor, a bucket conveyor and the like can be adopted. In addition, soil is extracted continuously or intermittently by various pumps, valve opening and closing.
As a means to return overflow water (separated wastewater after washing) that has floated near the liquid level in the washing tank to the settling basin, for example, the separation liquid is allowed to overflow from the overflow weir installed in the upper part of the washing tank. Return it to a sand basin (sewage treatment facility) using a liquid return pipe. When returning the separation liquid, it may be pumped or may fall naturally by inclining the flow path.

The concentration of diluted sand and separated sand after dilution and mixing is 10% (w-dry earth / w-water) or less, preferably 5% (w / w) or less. If it exceeds 10%, blockage occurs in the sand settling machine or the water pipe.
The volume load of the liquid to be treated per inclined plate projection area of the inclined plate type sedimentation apparatus is 5 to 25 m ³ −treatment liquid / m ² −inclined plate projection area / hr, preferably 7.5 to 15 m ³ / m ^2. / Hr. If it is less than 5 m ³ / m ² / hr, a large amount of residue (organic matter) is trapped by the inclined plate, and the organic matter content (heat loss) cannot be reduced. On the other hand, when it exceeds 25 m ³ / m ² / hr, the recovery rate of fine silt such as silt and fine sand is remarkably lowered, and much sand having a particle size of 100 to 200 μm is deposited on the pipes and water pipes of the sewage treatment plant. It flows out as overflow water (separated water) and cannot fulfill the original purpose of preventing sediment accumulation in piping and water pipes.

The supply amount of fine bubbles is 0.3% (v-air [Nm ³ ] / v-sewage [m ³ ]) or more, preferably 0.5 to 1% (v / v) per sewage (treatment target liquid). ). If it is less than 0.3%, the cleaning effect of separating the organic matter and fine earth and sand due to the shear force between the mixture of air bubbles and fine bubbles will be insufficient, and the floating effect will be reduced due to insufficient adhesion of bubbles to the organic matter. Can't wash off well.
The air mixing amount in the mixed water of the fine bubble supply device is 10% (v-air [NL] / v- [L]) or less, preferably 1 to 6% (v / v). If it exceeds 10%, bubbles in the mixed water ejected from the mixed water injection nozzle will be bubbled together and become larger before being dispersed in the washing tank. It is preferable to mix water and air into a mixed water before jetting from the jet nozzle by installing an ejector or a line mixer between the jet nozzles after mixing air with the supply pressure water.
The jet velocity of the mixed water from the mixed water injection nozzle of the fine bubble supply device is 6 m / sec or more, preferably 12 m / sec or more. By making the jet velocity of mixed water higher than 6m / sec, the bubbles are made finer, and the mixed water is vigorously applied to the settling sand to solve the entanglement of earth and sand (especially pulp fiber). The organic matter that has sunk at the bottom of the inclined plate type sedimentation separator can be rolled up by the effect of the separation and sedimentation with earth and sand. If it is less than 6 m / sec, such an effect cannot be obtained.

  The invention according to claim 2 is a sand feed pump system in which the sand settling machine is pressure-feeding the sand set collected by the bucket conveyor, or an air-mixed jet pump system in which the settling sand is sucked and transferred by using pressurized water and air. It is a sand-washing apparatus of Claim 1.

According to the second aspect of the present invention, in the case of a sand feeding pump type or mixed jet pump type sand settling machine, water is sent as sewage together with a large amount of dilution water, so that the sand and sand are preliminarily stored in the water feeding pipe. There is an effect that organic matter is dispersed.
Compared to the sand pump method, the mixed-air jet pump method has the advantage that the organic matter and the earth and sand are more easily dissolved when air enters, and bubbles are easily attached to the organic matter. On the other hand, however, there are disadvantages such as a large amount of water transported and a large amount of sand settling apparatus, and a large collection of air bubbles and air bubbles before the sand settling apparatus is separated, resulting in a decrease in sediment recovery rate.
As a bucket conveyor, what mixes the sand sinked up by the V-shaped bucket conveyor in the sewage currently transferred by a sand settling machine etc. can be employ | adopted, for example.
The air-jet pump is a pump that uses air and pressurized water as power for vacuum suction transfer.

  According to a third aspect of the present invention, the inclined plate type sand-washing separator is an inclined plate group in which inclined plates in which a plurality of inclined plates are arranged in parallel with each other in a state of being parallel to each other are accommodated in the cleaning tank. The sand-washing apparatus according to claim 1 or 2.

  According to a fourth aspect of the present invention, the inclined plate type sandwashing separator is configured so that a conical spiral plate in which a spiral flow path is formed in the cylindrical washing tank is centered on a rotation axis whose axis is vertical. It is a spiral separator rotated by a rotation means, It is a sand settling apparatus of Claim 1 or 2.

  According to a fifth aspect of the present invention, the separated sand separated by the liquid cyclone of the pre-concentration pretreatment facility or the pre-mud pretreatment facility from the settling sludge of the first settling basin is disposed in the sewage being transferred by the sand settling machine. It is a sand settling apparatus of any one of Claims 1-4 in which the dredged material sand accumulated in the pipe line facility is mixed.

  According to the fifth aspect of the present invention, the separated sand separated by the hydrocyclone is mixed into the sewage water being transferred by the sand settling machine, so that it can be processed without the need for separate dilution water. . In the past, most of the sediment in the separated sand flowed out of the sand-washing tank and circulated in the sewage treatment plant. However, by increasing the recovery rate of the sediment in the separated sand, the circulation rate was reduced and the load on the hydrocyclone was reduced. By reducing this, troubles in the sludge concentrator and sediment accumulation in the mud pipe can be reduced.

In order to avoid mechanical troubles with the sludge concentrator and the sludge dewatering device, the mud pretreatment facility reduces sediment in order to reduce deposits in the mud pipe and prevent clogging.
The liquid cyclone is an apparatus that separates earth and sand from the first settling sludge thrown into the upper part of the cyclone tower by a cyclone method using centrifugal force, and collects 80 to 90% of sand having a particle size of 150 μm or more.

Invention of Claim 6 is a sand-washing apparatus of any one of Claims 1-5 whose magnitude | size of the said micro bubble immediately after injection from an air-mixed water injection nozzle is 1 mm or less. .
If the size of the fine bubbles exceeds 1 mm, bubbles are less likely to be attached to the organic matter, and the rising speed of the bubbles is increased to cause upward drift, thereby reducing the separation efficiency and the sediment recovery rate. A preferable size of the fine bubbles is 0.01 to 0.5 mm. Within this range, the fine sand, silt, clay and organic matter in the sand can be dissolved by the local shearing force generated by the mixed water jet nozzle and the bubbles, and the organic matter floats by attaching the fine bubbles to the organic matter. A more suitable effect of improving the property and promoting the separability between the organic matter and the earth and sand can be obtained.

According to the first aspect of the present invention, mixed water is ejected into the washing tank to wash away the organic matter contained in the sand. At this time, since the mixed water contains fine bubbles, the earth and sand in the settling sand and the organic matter can be solved. In addition, by attaching fine bubbles to the organic matter, the floatability of the organic matter can be improved, and the separability between the organic matter and the earth and sand in the inclined plate type sedimentation separator can be enhanced. Furthermore, by blowing fine bubbles as mixed water into the washing tank, especially at the bottom, fiber organic matter such as paper fibers and hair co-precipitated with earth and sand, or residue such as coarse vegetable scraps and tobacco filters are again removed. Can be washed and washed out.
In addition, an inclined plate type sandwashing separator is adopted, so when sewage flows into the parallel gap between the inclined plates, the separation time between organic matter and earth and sand can be shortened, and gravity separation can be performed efficiently using the specific gravity difference. it can. As a result, a high recovery rate of the earth and sand contained in the sewage and a high removal rate of the organic matter contained in the earth and sand can be obtained at the same time.

  According to the second aspect of the present invention, when a sand transport pump type or mixed jet pump type sand settling machine is adopted, water is fed as sewage together with a large amount of dilution water, so that There is an effect that earth and sand and organic matter are dispersed.

  According to invention of Claim 4, since the spiral separator was employ | adopted as an inclined plate type sand-washing separator, an upward flow and a fine bubble can be received uniformly by the whole inclined plate. This suppresses the stirring force by the mixed water jet nozzle to the entire sand washing tank, eliminates upward drift due to bubbles, and draws the liquid to be treated into the inclined plate group without disturbing the flow by optimal rotation. The effect that high separability can be maintained while stirring under the board group with mixed water is obtained.

  According to the fifth aspect of the present invention, the separated sand separated by the liquid cyclone is mixed into the sewage being transferred by the sand settling machine, so that it can be processed without requiring dilution water separately. It is. In the past, most of the sediment in the separated sand flowed out of the sand-washing tank and circulated in the sewage treatment plant.However, by increasing the recovery rate of the sediment in the separated sand, the circulation rate was reduced and the liquid cyclone was recycled. By reducing the load, troubles in the sludge concentrator and sediment accumulation in the mud pipe are reduced.

Examples of the present invention will be specifically described below.
In FIG. 1, reference numeral 10 denotes a sand settling device for washing the sand settling on the bottom of a sand settling basin 11 of a sewage treatment plant according to Embodiment 1 of the present invention. This sand settling apparatus 10 has a washing tank 13 for introducing sewage containing organic matter and earth and sand transferred from the bottom of a sand settling basin 11 by a sand settling machine 12, and is housed in this washing tank 13 and has a conical spiral plate ( A spiral separator (inclined plate type sand-washing separator) 15 that separates organic matter and earth and sand from the sewage flowing into the parallel spiral flow path (gap) 14a between the inclined plates) 14 using gravity difference; An air-mixed water production machine 17 for jetting mixed water containing fine bubbles into the washing tank 13 from the nozzle 16 to wash the settling sand, and a sediment collection conveyor (sand raising) for collecting the washed sand from the lower part of the washing tank 13 This is a device for returning the separation liquid containing organic substances floating near the liquid surface of the washing tank 13 to the sand settling basin 11.

Hereinafter, these configurations will be described in detail.
The sand basin 11 is a sand basin of a sewage treatment plant into which sewage from a sewer main line is directly introduced.
As the sand settling machine 12, a mixed-air jet pump system that uses pressurized water and air to suck and transfer the settling sand together with the sewage is employed. This is a pump using air and pressurized water as power for vacuum suction transfer. In addition, you may employ | adopt the sand-sink-pump type sand-sediment transfer machine 12A which sends the sand-sediment collected with the V-shaped bucket conveyor 19 with dilution water. This is a method in which the sand settling on the bottom of the settling basin 11 is scraped up by the V-shaped bucket conveyor 19 and once stored in the settling tank 12a, the settling sand in the settling tank 12a is fed together with dilution water by the sand pump 20. It is.

The sewage containing the sand settling by vacuum suction by the sand settling machine 12 is introduced into the washing tank 13 of the sand settling apparatus 10 through the sand settling pipe 21. In the middle of the sand settling pipe 21, sewage containing separated sand separated by the hydrocyclone 24 of the dewatering / mud pretreatment facility 23 is mixed.
In the dewatering / mud pre-treatment facility 23, the first settling sludge is introduced from a part of the upper peripheral side surface of the hopper of the liquid cyclone 24, and the separated sand centrifuged in the cyclone 24 is supplied to the screw conveyor 25 from the lower end of the hopper. Put in the lower end. On the other hand, the separated sludge discharged from the upper end of the hopper is transferred to the mud well and processed. The separated sand transferred to the upper end of the screw conveyor 25 falls to the separated sand dissolving tank 26 immediately below. Here, while supplying a predetermined amount of dissolved water, the compressed air from the dilution tank aeration blower 27 is bubbled, and stirring by the stirrer 28 is performed. In this way, the separated sand that has settled at the bottom of the separated sand dissolution tank 26 is introduced into the settling sand supply pipe 21 by the separated sand transfer pump 29.

Next, the spiral separator 15 will be described in detail with reference to FIG.
Here, as an inclined plate type sandwashing separator, a conical spiral plate 14 in which a spiral flow path 14a is formed is rotated by a rotary motor 30 around a rotation axis whose axis is vertical in a cylindrical washing tank 13. A spiral separator 15 is employed.
The spiral separator 15 has a cleaning tank 13. A lower portion of the cleaning tank 13 is a hopper portion 31 that gradually tapers downward. A central sand outlet 32 is formed at the lower end of the hopper 31.

A cough (wear) 34 is formed at the upper end of the cylindrical wall 33 of the cleaning tank 13, and an annular basket 35 for collecting a separated liquid (sewage containing organic matter) is formed around the cough 34. Yes. The separation liquid that has flowed down into the annular trough 35 is returned to the sand basin 11 by a separation liquid return pipe (not shown).
The tip of the inlet cylinder 36 at the center of the upper end of the cleaning tank 13 into which sewage containing sedimentation flows enters the cleaning tank 13 from the center of the upper lid 37 of the cleaning tank 13 and extends inward toward the axis of the cleaning tank 13. Exists. Around the inlet tube 36, a cylindrical tubular wall (rotating shaft) 38 extending from above the position of the liquid surface to approximately the middle of the cylindrical portion of the cleaning tank 13 is disposed.

  The outer surface of the cylindrical annular wall 38 is a series of conical spiral plates 14 extending downwardly and outwardly from the cylindrical annular wall 38 and extending around the cylindrical annular wall 38 in a more fitted helical shape. Support. The conical spiral plate 14 extends radially so as to converge at a location adjacent to the cylindrical wall 33 of the cleaning tank 13. The inclination of the conical helix 14, that is, the angle formed between the radiation on the surface of the conical helix 14 and the axis of the helix is about 45 °, which is the same left hand as the bolt thread. The rotational speed of the conical spiral plate 14 and the pitch of the conical spiral plate 14 are preferably adjusted in accordance with the vertical flow rate (no swirl speed) of sewage containing sand. At this “non-vortex speed”, the fluid flows through the cleaning tank 13 in a substantially vertical direction.

The conical spiral plate 14 and the cylindrical annular wall 38 can be rotated rightward about the axis of the cleaning tank 13 by a rotary motor 30 disposed near the center of the upper lid 37.
The sewage containing sedimentation that flows into the cylindrical annular wall 38 from the inlet cylinder 36 is discharged on or near the water surface in the internal space of the cylindrical annular wall 38.
Thereafter, the sewage containing the settling sand flows downward in the axial direction in the cylindrical annular wall 38 until it reaches the lower end of the cylindrical annular wall 38. The direction of the flow is reversed here, and the sewage containing sedimentation flows upward through the array of conical conical spiral plates 14.

While the sewage containing sedimentation passes upward between the conical spiral plates 14, the earth and sand as particulate matter is separated and deposited on the upper surface of the conical spiral plate 14. This earth and sand moves downward and radially outward along the upper surface of the plate, and is discharged in the vicinity of the cylindrical annular wall 38 of the cleaning tank 13. Thereafter, the earth and sand sink into the hopper portion 31 of the cleaning tank 13 and are discharged from the central sand outlet 32. At this time, the mixed water generated by the mixed water manufacturing machine 17 is ejected from the nozzle 16 fixed to a part of the peripheral wall of the hopper unit 31 toward the center of the hopper unit 31.
The air-mixed water production machine 17 includes a pump for pumping treated water of the sand sediment washing apparatus 10, a compressor (not shown) that generates compressed air, and a mixer (ejector) 40. Due to the jet of mixed water into the washing tank 13, large organic matter containing relatively large sediments and sediment particles and entangled fibrous organic matter that have been settled are wound up again, and the soil washing effect is further enhanced. The direction of the nozzle 16 outlet is preferably downward, but may be upward.

  The lower end of the hopper 31 of the cleaning tank 13 communicates with the lower end of the transport pipe 41 of the earth and sand recovery conveyor 18 that recovers the washed earth and sand from the lower part of the cleaning tank 13. The earth and sand recovery conveyor 18 is inclined with the support 42 interposed therebetween. An opening 43 communicating with the central sand outlet 32 is formed at the lower end of the earth and sand collection conveyor 18. A screw 44 is rotatably accommodated in the transport tube 41. An electric motor 45 that transmits a rotational force to the screw 44 is fixed to the upper end portion of the transport pipe 41 via a pulley-type power transmission unit. In addition, a discharge port 46 for the collected sand is formed at the upper end of the transport pipe 41. The earth and sand discharged from the discharge port 46 are temporarily stored in the sand washing storage hopper 47, then dropped onto the truck bed and transported to the landfill.

Next, an operation method of the sand sediment washing apparatus 10 according to Embodiment 1 of the present invention will be described.
As shown in FIG. 1, air and pressurized water are used as power for vacuum suction transfer by an air-jet pump type sand settling machine 12, and the sand settling on the bottom of the sand settling basin 11 together with sewage is passed through a sand settling pipe 21. It is introduced into the cleaning tank 13 of the sand settling device 10, specifically, the inlet cylinder 36 of the spiral separator 15. In the middle of the sand settling pipe 21, sewage containing separated sand separated by the hydrocyclone 24 of the dewatering / mud pretreatment facility 23 is mixed.

  The sewage containing sedimentation introduced into the inlet tube 36 is discharged on or near the water surface in the internal space of the cylindrical annular wall 38. In the spiral separator 15, sewage containing sedimentation is supplied from the inlet cylinder 36 to the internal space of the cylindrical annular wall 38. Thereafter, the sewage containing the settling sand descends in the cylindrical annular wall 38 and descends to the hopper portion 31 of the cleaning tank 13. At this time, the conical spiral plate 14 is rotated clockwise by the rotary motor 30 through the cylindrical annular wall 38. For this reason, the sewage including the sand settled once toward the hopper portion 31 rises including fine earth and sand and organic matter, and flows into the spiral flow path 14 a below the conical spiral plate 14. Thereafter, the sewage rises along the spiral flow path 14 a as the conical spiral plate 14 rotates. At this time, the mixed water generated by the mixed water manufacturing machine 17 is ejected from the nozzle 16 fixed to a part of the peripheral wall of the hopper unit 31 toward the center of the hopper unit 31. As a result of the jet of mixed water into the washing tank 13, large organic matter containing sediments or sediment particles or entangled fibrous organic matter is wound up again as it is, and the organic matter is unraveled and floated. The cleaning effect is further enhanced.

While the sewage containing fine earth and sand and the organic matter rises along the spiral flow path 14a, the earth and sand in the sewage and the liquid are separated into solid and liquid. Many of the light organic substances increase with liquid content. The earth and sand, which is solid content, rolls down on the inclined surface of the conical spiral plate 14, is rolled up from the central sand outlet 32 at the lower end of the hopper 31 via the earth and sand collection conveyor 18, and is temporarily stored in the sand washing storage hopper 47. After that, it is dropped onto the truck bed and transported to the landfill.
On the other hand, the separated liquid containing the organic matter that has been washed and separated from the sedimented sediment rises to the vicinity of the upper end of the washing tank 13, and the overflowed separated liquid overflows the cough 34 and overflows into the annular basin 35. It is returned to 11 by natural fall. Some organic matter settled together with the earth and sand trapped in the conical spiral plate 14 is also washed again with the mixed water ejected from the nozzle 16, and the apparent specific gravity becomes lighter by attaching fine bubbles, resulting in a spiral shape. It passes through the flow path 14a and overflows into the annular trough 35.

As described above, the mixed water containing fine bubbles is ejected from the nozzle 16 into the washing tank 13 to wash away the organic matter adhering to the sand. Since the mixed water contains fine bubbles, the sediment and organic matter in the sand can be dissolved, and the floating property of the organic matter is improved by adhering the fine bubbles to the organic matter, so that the spiral separator 15 separates the organic matter and the sediment. Can increase the sex. Moreover, by blowing fine bubbles into the washing tank 13 as air-mixed water, particularly from the nozzle 16 to the bottom thereof, the soil and sand particles are separated from the fibrous organic matter such as paper fibers and hair co-precipitated with the sediment and the fibrous organic matter. Alternatively, coarse residue such as coarse vegetable scraps and tobacco filters can be washed again and washed away.
In addition, since the spiral separator 15 is adopted, when the sewage flows into the parallel spiral flow path 14a between the conical spiral plates 14, the sedimentation speed difference between the earth and sand and the organic matter is given, and the gravity is efficiently utilized by utilizing the specific gravity difference. Can be separated. Thereby, the high recovery rate of the earth and sand contained in sewage and the high removal rate of the organic substance contained in sewage sand can be obtained simultaneously.

Since the mixed-air jet pump type sand settling machine 12 and the mixed-air jet pump type sand settling machine are adopted, the soil and organic matter are dispersed in advance in the water supply pipe by being fed as sewage with a large amount of diluted water. Is obtained.
Further, since the spiral separator 15 is adopted as the inclined plate type sandwashing separator 15, the upward flow and the fine bubbles can be uniformly received by the entire conical spiral plate 14. This suppresses the stirring force by the mixed water jet nozzle to the entire sand washing tank, eliminates upward drift due to bubbles, and draws the liquid to be treated into the inclined plate group without disturbing the flow by optimal rotation. The effect that high separability can be maintained while stirring under the board group with mixed water is obtained.
In addition, it is possible to obtain high separation efficiency with the entire inclined plate, suppress upward drift caused by fine bubbles, and collect excess bubbles that do not adhere to organic matter to the cylindrical annular wall 38, and collect the cylindrical annular wall from the collection hole. By taking in the inside of 38, the effect which eliminates the disturbance of the water flow in the spiral flow path 14a is acquired.
Furthermore, since the separated sand separated by the liquid cyclone 24 is mixed into the sewage being transferred by the sand settling machine 12, it can be processed without requiring separate dilution water. In the past, most of the sediment in the separated sand flowed out of the sand-washing tank and circulated in the sewage treatment plant.However, by increasing the recovery rate of the sediment in the separated sand, the circulation rate was reduced and the liquid cyclone was recycled. By reducing the load, troubles in the sludge concentrator and sediment accumulation in the mud pipe and pit are reduced. In other words, it becomes possible to simultaneously wash and collect the fine sediment of 200 μm or less that has passed without being captured by the sedimentation basin, and there is little fine sediment of 200 μm or less that returns to the hydrocyclone 24 again through the sedimentation basin 11 and the first sedimentation basin. can do. For this reason, the amount of earth and sand transferred from the hydrocyclone 24 to the mud well with the sludge is reduced, and the effect of reducing the earth and sand accumulated in the mud pipe and the pit can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the sand settling apparatus which concerns on Example 1 of this invention. It is an expanded sectional view of a spiral separator which constitutes a part of a sand settling device concerning Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sedimentation washing apparatus 11 Sedimentation basin 12 Sedimentation transfer machine 12A Sedimentation pump type sedimentation transfer machine 13 Washing tank 14 Conical spiral plate (inclined plate)
14a Spiral channel (gap)
15 Spiral separator (rotating inclined plate type sedimentation separator)
16 Nozzle 17 Mixed Water Production Machine 18 Sediment Collection Conveyor 19 Bucket Conveyor 23 Dehydration and Mud Pretreatment Equipment 24 Hydrocyclone 30 Rotating Motor (Rotating Means)

Claims (6)

It has a washing tank that introduces sewage containing organic matter and earth and sand transferred from the bottom of the sand settling basin by a sand settling machine,
An inclined plate type sandwashing machine that gravity-separates the organic matter and the earth and sand from the sewage that is stored in the washing tank and flows into parallel gaps between the inclined plates using a difference in specific gravity,
An air-mixed water producing machine for cleaning the earth and sand by jetting air-mixed water containing fine bubbles in the cleaning tank;
A sediment collection conveyor for collecting the washed soil from the lower part of the washing tank,
A sand sediment washing apparatus comprising a pipe for returning a separation liquid containing an organic substance floating near the liquid surface of the washing tank to the sand settling basin.   2. The sand sediment washing apparatus according to claim 1, wherein the sand sediment transporter is a sand feed pump system that pumps sand collected by a bucket conveyor or an air-mixed jet pump system that sucks and transports sediment by using pressurized water and air. .   3. The sand-washing machine according to claim 1, wherein the inclined-plate type sand-washing separator is an inclined plate group in which inclined plates in which a plurality of inclined plates are arranged in parallel with each other are accommodated in the cleaning tank. apparatus.   The inclined plate type sandwashing separator is a spiral separator that rotates a conical spiral plate, in which a spiral flow path is formed, in a cylindrical washing tank by a rotating means about a rotation axis whose axis is vertical. The sand settling apparatus according to claim 1 or 2.   In the sewage being transferred by the sand settling machine, the separated sand separated from the settling sludge of the first settling basin by the liquid cyclone of the concentration pretreatment facility or the mud pretreatment facility and the dredged sediment deposited on the pipe facility are collected. The sand settling apparatus of any one of Claims 1-4 mixed.   The sand sediment washing apparatus according to any one of claims 1 to 5, wherein the size of the fine bubbles in the mixed water immediately after ejection from the mixed water ejection nozzle of the mixed water production machine is 1 mm or less.

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