JPH0520402Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for preventing the occurrence of short passes, so-called "water paths", during discharge of concentrated slurry from a sludge extraction pit of a thickening tank in a waterworks wastewater treatment facility.

[Conventional technology]

In general, thickening tanks in waterworks water wastewater treatment equipment are either intermittent (receiving water every few days or months) or continuous, depending on the scale of the preceding water treatment equipment, the sedimentation tank drainage method, and the sludge treatment method after the thickening tank. The functions of the thickening tank are: Solid-liquid separation of suspended solids and turbid substances contained in the inflow water (thickening tank surface area - separation area) Reducing the volume of the sedimentation slurry by promoting concentration of the separated sedimentation slurry (Facilitation of solid-liquid replacement using pile consolidation, rake arms, and blades) Storage of concentrated slurry (sufficient tank capacity that does not impede solid-liquid separation), etc.

Up to now, measures have been taken to promote the concentration of the separated sedimentation slurry, such as installing a pit pipe to promote solid-liquid exchange, installing a secondary concentration section, or enlarging the pit. In Figure 4,
The general shape of a thickening tank is shown, and solid-liquid separation and thickening of inflow water, and sludge removal are explained.

The inflowing water flows into a cylindrical feedwell c fixed to the driving device pier mount b through a raw water inflow pipe a. Next, the inflow water flows out radially from the lower opening d of the feed well c over the entire surface of the concentration tank and begins to rise toward the water surface f of the concentration tank e.
The flow rate of the inflow water is changed to an upward flow rate, which is rapidly reduced from the time it leaves Feedwell C, and suspended matter and turbidity with heavy specific gravity contained in the inflow water begin to separate and settle against the upward flow rate, resulting in concentration. It reaches the bottom g of tank e. The slurry that has reached the bottom g of the thickening tank e is solid-liquid exchanged by compaction, slow movement by the rake arm h, blade i, etc., and shearing, and the slurry concentration is increased while the sludge is deposited in the center of the tank e. It is transferred to the extraction pit j.

The concentrated slurry transferred to the sludge extraction pit j is retained in the sludge extraction pit j until it is drained, and is stirred at a low speed by the lower blade k, whereby solid-liquid replacement is further performed. This results in a concentrated slurry with accelerated concentration.

The sludge drainage pipe is for discharging the concentrated slurry accumulated in the sludge extraction pit j out of the tank, and is connected to the suction port of a sludge extraction pump (not shown). The amount is forcibly discharged out of the tank within a predetermined period of time.

[The problem that the idea attempts to solve]

By the way, considering the state of sludge drainage, (1) Concentrated slurry remains in the bottom g of the thickening tank e and in the sludge extraction pit j.

(2) The purpose of the rake arm h, blade i, and lower blade k is to move the slurry at very low speed, cut it forward, and scrape it up.

(3) Rake arm h, blade i, and lower blade k have low rotational speeds (peripheral speeds that do not hoist sedimented slurry).

(4) Discharge of concentrated slurry takes a short time (several hours a day)
A large amount is forcibly discharged.

(5) Due to forced discharge, the concentrated slurry near the discharge port is discharged, but due to the phenomenon of suctioning objects with low specific gravity and low resistance, a short pass, so-called ``water path'' m, is created as shown in Figure 5. Cheap.

(6) Once the "water path" m is created, the low-concentration slurry and the concentrated sludge raked up by the rake arm h and blade i will be alternately sucked up.

(7) Concentrated slurry cannot be sucked stably.

(8) Unless more slurry is discharged than necessary, the capacity of the sludge treatment equipment cannot be satisfied.

From the above, in order to stably suction and discharge the concentrated slurry at the bottom of the thickening tank and in the sludge extraction pit at a high concentration, it is necessary to create a state in which "water channels" are difficult to form.

[Means for Solving the Problems] Here, the present invention is to provide a main shaft of a scraper with a lower blade installed in a sludge extraction pit of a thickening tank of a waterworks wastewater treatment facility. A cap-like cover shaped to cover the sludge extraction pit is provided on the top, and a plurality of slits for raising the solid-liquid replacement water are radially bored in the cover, and the concentrated slurry is poured into the bottom of the cover. We propose a shot pass prevention device in a sludge extraction pit of a thickening tank, which is constructed by arranging a plurality of blades for scraping sludge into the sludge extraction pit, and in implementing the device, the blades are arranged in a spiral shape and adjacent to each other. The inner and outer edges of the blade overlap in the radial direction to prevent backflow of the concentrated slurry.

[Effect]

That is, in the device of this invention having the above-mentioned configuration, a cap-shaped cover having a shape that covers the sludge extraction pit is provided directly above the lower blade disposed in the sludge extraction pit, and a plurality of slits are formed in this cover. By drilling radially and arranging a plurality of blades in a spiral manner on the underside of this cover,
Separated water resulting from solid-liquid displacement is raised through the slit, and the inflow and concentrated slurry is sent into the sludge extraction pit without backflowing.

〔Example〕

Next, an embodiment of this invention will be explained with reference to FIGS. 1 to 3. Note that illustrations and explanations of the configurations and functions of parts that are not directly related to the explanation of this invention, such as the raw water inlet pipe and the feedwell, will be omitted.

A sludge extraction pit 3 is located in the center of the bottom 2 of the thickening tank 1.
A lower blade 5 is provided in the sludge extraction pit 3 and is connected to a scraper main shaft 4 which is rotationally driven by a drive device (not shown).
A sludge drainage pipe 6 is led out from the bottom of the sludge extraction pit 3. The scraper main shaft 4, to which the rake arm 7 and the blade 8 are attached, is equipped with a canopy-like cover 9 directly above the lower blade 5, and this cover 9 completely covers the sludge extraction pit 3. It has a size that covers the second
As shown in the drawings and FIG. 3, a plurality of slits 10 are formed radially, and a plurality of spiral-shaped blades 11 are attached to the lower surface. These blades 11 are arranged so that the inner edges 11a and outer edges 11b of adjacent blades overlap each other in the radial direction.

In the above configuration, the concentrated slurry raked by the rake arm 7, blade 8, and each blade 11 is stirred and sheared in the sludge extraction pit 3, and the separated water subjected to solid-liquid substitution is transferred to the slit 1.
The concentrated slurry in the sludge extraction pit 3 is discharged through the sludge drain pipe 6 at predetermined intervals.

In fact, in the framework constituting the covering body 9, a round bar, plate, etc. 12 is placed toward the sludge extraction pit 3.
Stirring of concentrated slurry by installing
Shearing and "water path" breaking effects can be facilitated.

[Effect of idea]

According to the device of this invention having the above configuration, the following effects can be obtained. In other words, it has a simple structure that can be directly connected to the raking machine main shaft.

By completely covering the sludge extraction pit, you can trap the inflowing concentrated slurry and create a water path.
can prevent the formation of

It has a slit for raising separated water during solid-liquid replacement.

The blades overlap and the incoming concentrated slurry does not flow back.

The sludge extraction pit part becomes a chamber with the blade and cover.

, When sludge is produced, it becomes difficult to form a "water channel" and only concentrated slurry is discharged.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a concentration tank equipped with the device of this invention, Figure 2 is an enlarged sectional view showing the main parts of this invention, Figure 3 is a plan view of the part shown in Figure 2, and Figure 4 is FIG. 5 is a sectional view of a conventional device, and is an explanatory diagram showing a state in which a short path (water path) is formed. In the figure, 1... thickening tank, 3... sludge extraction pit, 4... main shaft of scraper, 5... lower blade, 9... cap-shaped cover, 10... slit, 11
...Blade.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) The sludge pulling machine is installed on a scraper main shaft with a lower blade installed in a sludge drawing pit of a thickening tank of a waterworks water wastewater treatment facility, and the sludge drawing machine is installed directly above the lower blade. A cap-like cover shaped to cover the pit is provided, and a plurality of slits for raising solid-liquid water displacement are radially bored in the cover, and the bottom surface of the cover is used to scrape the concentrated slurry into the sludge extraction pit. A shot pass prevention device in a sludge extraction pit of a thickening tank, which is equipped with a plurality of blades for gathering sludge. (2) The concentrate according to claim 1, wherein the blades are arranged in a spiral shape and the inner and outer edges of adjacent blades overlap in the radial direction so that backflow of the concentrated slurry can be prevented. Short pass prevention device in the sludge extraction pit of a tank.