JP2011200865A - Scum removal apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scum removal apparatus which can efficiently remove scum generated on the water surface.SOLUTION: A defoaming device 8 operated with a rotary shaft 6 of a stirring impeller 5 installed in a reaction tank is provided at a water surface part of the rotary shaft 6. The defoaming device 8 comprises a scum-scraping rake 11 fixed to the rotary shaft 6, and a screen 12 installed on the liquid surface inside the turn locus of the rake 11, and compresses scum S on the screen by the rake 11 to release gas, precipitating it as sludge. Further, the screen 12 is a mesh texture body 13, and crushes the scum S through meshes of the mesh texture body 13 responded to the rake 11 as a scum-crushing device for releasing the scum gas to precipitate the sludge into a liquid.

Description

  The present invention relates to a scum removing device that can efficiently remove scum generated on the water surface of a reaction tank in a sewage treatment plant.

  Conventionally, as a treatment method of sewage, as shown in Patent Document 1, the raw water is stirred in an anaerobic state or an oxygen-free state without dissolved oxygen without blowing air in the previous stage of the aeration zone, so that the sewage is more highly purified. A system has been developed and is in use.

However, in a reaction tank in an anaerobic state or an oxygen-free state, bubbles accompanied with sludge called scum are generated on the water surface, causing various problems. That is, since this scum is sludge with CO ₂ gas floating, if left as it is, the sludge hardens and the entire surface of the tank is covered with a thick scum layer, and the state of the treated water is changed. There were problems such as being unable to visually check, causing odor when left for a long period of time, causing stickiness to become debris and hindering defoaming by watering, and deteriorating aesthetics. .
The aerobic tank and anaerobic tank, and the anaerobic tank and anoxic tank partition walls are separated from each other to prevent the flow of dissolved oxygen and liquid mixture, and the treated water flows through the lower part of the partition walls. Since there is no place for the scum generated on the water surface to flow out, the scum was more likely to stay on the water surface of the reaction tank.

Therefore, until now, as a scum removal method, the scum is aerated by sprinkling water on the scum that has just occurred and defoaming, or by temporarily opening a weir plate near the water surface provided in the partition wall with the downstream tank. It was dealt with by measures such as pouring into the tank side, but it was forced to do extra work and inferior in workability, and constantly watering was a waste of water resources and energy, Since the work of pouring scum into the aeration tank is performed manually, the number of personnel is increased, and there is a problem that the processing efficiency is lowered due to temporary circulation.
Japanese Patent No. 2912905

  The present invention solves the above-described problems, and can remove scum generated on the water surface automatically and efficiently continuously and at low cost without generating extra work and personnel. The present invention has been completed for the purpose of providing a removal device.

  The scum removing device of the present invention made to solve the above problems is a scum removing device provided with a defoaming device operating along with the rotating shaft on the water surface of the rotating shaft installed in the reaction tank, The defoaming device consists of a rake for scraping the scum fixed to the rotating shaft and a screen installed on the liquid surface in the trajectory of the rake. The scum on the screen is compressed by the rake and the scum is This is characterized in that the gas is discharged and settled as sludge.

  Further, the screen is a net-like body, and as a scum crushing tool for discharging scum gas, it is preferable that the scum is crushed through the mesh of the net-like body corresponding to the rake and the sludge is settled in the liquid. Such an invention.

  In the invention according to claim 1, since the defoaming device that operates together with the rotating shaft is provided on the water surface of the rotating shaft installed in the reaction vessel, the defoaming device automatically operates along with the rotation of the rotating shaft. Thus, the scum floating around the rotating shaft can be removed. The defoaming device comprises a rake for scraping the scum fixed to the rotating shaft and a screen installed in the trajectory of the rake. The scum on the screen is compressed and sheared by the rake. Since the gas is discharged and settled as sludge, the scum gas is automatically discharged on the screen and settles as sludge as the stirring blades rotate, and the scum is removed.

  In the invention according to claim 2, the screen is a mesh body, and the scum is crushed through the mesh of the mesh body corresponding to the rake as a scum crushing tool for discharging the scum gas, so that the sludge is settled in the liquid. When gas passes through the mesh, gas is released and settles as sludge, and scum is efficiently removed.

It is a schematic whole view which shows a processing tank. It is a perspective view which shows the lower part of a stirring blade. (A) The top view which shows a defoaming apparatus, (b) The operation | movement explanatory drawing. (A) The top view which shows another defoaming apparatus, (b) The operation | movement explanatory drawing.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic overall view showing a treatment tank for advanced treatment of raw water such as sewage. The treatment tank 1 is a deep tank type having a width and depth of about 10 m and a length of about 50 m. In order to perform advanced treatment, the anaerobic zone B in which the front stage of the treatment tank 1 is in an anaerobic state, dissolved oxygen This is an anoxic zone C in a state where there is no state. A is an aeration zone. The anaerobic zone B and the oxygen-free zone C are separated from each other by the partition wall 2, and the oxygen-free zone C and the aeration zone A are separated from each other by the partition wall 3.
As shown in FIG. 1, a circulation path 20 is connected to feed back a portion of treated water aerated and nitrified in the aeration zone A to the anoxic zone C as a nitrification liquid, thereby denitrifying. Is configured to be performed.

  A baffle plate (not shown) is vertically provided at the center in the width direction of the aeration zone A, and an air diffuser 4 is installed in the intermediate water depth of the one-side flow path for aeration in the middle stage. Thus, it has a structure that creates a flow that swirls up and down on both sides of the baffle plate. In addition, the said air diffusing device 4 is mounted, for example, on a beam (not shown) installed at intervals of 2 to 3 m.

In the anaerobic zone B and the oxygen-free zone C, a stirring blade 5 is provided at the center of the bottom surface of each zone. This stirring blade 5 is installed for the purpose of stirring the sludge so as to promote the removal of nitrogen and phosphorus in the raw water and to stabilize the sludge sedimentation by suppressing the generation of filamentous fungi. It is.
As shown in FIG. 2, the stirring blade 5 is a two-stage blade composed of a substantially straight upper blade 5a for generating a lateral flow and a substantially straight lower blade 5b for generating a downward flow. By attaching the step blades to the tip of the rotating shaft 6, sludge is not deposited on the bottom.

Moreover, the motor 7 which is a drive source of the stirring blade 5 is installed outside the upper surface of the tank body 1 and allows the stirring blade 5 to freely rotate normally, intermittently, decelerate and reversely rotate. As described above, since the motor 7 is outside the tank, maintenance management is easy, and if the motor 7 is periodically reversely rotated, the deposits attached to the blades can be easily peeled off.
Further, since the stirring blade 5 is attached to the tip of one long rotating shaft 6, it may be shaken by a swirling flow of sewage. In this case, the tip of the rotating shaft 6 is interposed via a steady-state member 9. If the structure is fixed to the bottom surface of the tank body 1, the rotating shaft 6 is firmly fixed and is not curved, and the stirring blade 5 is prevented from being shaken, so that the mixed liquid can be stirred efficiently.

The embodiment has a structure in which a defoaming device 8 for removing scum that operates together with the rotating shaft 6 is provided on the water surface of the rotating shaft 6 of the stirring blade 5.
As shown in FIG. 3, the defoaming device 8 comprises a scum scraping rake 11 fixed to the rotary shaft 6 and a screen 12 installed on the liquid surface within the rake rotation locus. The scum S on the screen is compressed by a rake 11 to release gas and settle as sludge. The rake 11 is made of elastic synthetic rubber or the like, and is attached to an arm 6 a that protrudes horizontally from the rotary shaft 6.
As shown in FIG. 3B, the scum S moved on the screen is compressed by the rake 11 to release the internal gas, and thereafter settled as sludge and easily separated and removed.
The screen 12 is preferably inclined so as to gradually float on the liquid surface with respect to the rake traveling direction in consideration of the ease of movement and compression of the rake 11.

Further, as shown in FIGS. 4A and 4B, when the screen 12 is made of a mesh body 13 and the internal gas of the scum S is compressed by the rake 11 and released, or when the mesh of the mesh body 13 is passed through. And then released as sludge.
The mesh opening of the mesh body 13 is preferably about 3 to 5 mm.

  Thus, according to the present invention, the water surface portion of the rotating shaft of the stirring blade is provided with a defoaming device that operates together with the rotating shaft, so that it floats on the liquid surface while performing normal operation. The scum can be removed automatically and efficiently at a low cost.

DESCRIPTION OF SYMBOLS 1 Treatment tank 2 Partition 3 Partition 4 Aeration device 5 Stirrer blade 6 Rotating shaft 7 Motor 8 Defoaming device 9 Stabilizing member 11 Rake 12 Screen 13 Reticulated body 20 Circulation path S Scum

Claims (2)

  A scum removing device provided with a defoaming device that operates together with the rotating shaft on the water surface of the rotating shaft installed in the reaction tank, the defoaming device comprising a scum scraping rake fixed to the rotating shaft. And a screen installed on the liquid surface within the rotation trajectory of the rake, and the scum on the screen is compressed by the rake to release the gas inside the scum and settle as sludge. A scum removing device characterized by the above. 2. The scum removing device according to claim 1, wherein the screen is a net-like body, and the scum is crushed through the mesh of the net-like body corresponding to the rake as a scum crushing tool for discharging scum gas, and sludge is settled in the liquid.

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