JP2007275741A - Apparatus for electrolyzing sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for electrolyzing sludge, wherein scale stuck to a cathode plate is periodically removed in order to maintain stable electrolyzing performance. <P>SOLUTION: A cathode plate 20 is formed in such a manner that the upper part thereof comes up on the water-surface part, further, the cathode plate 20 is provided rotatably around the axis 20a orthogonal to the face thereof, and a scraper member 22 for cleaning the surface of the cathode plate 20, while coming in slide contact with the cathode plate 20 is arranged on the water-surface part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sludge electrolytic treatment apparatus, and more particularly to a sludge electrolytic treatment apparatus capable of maintaining stable electrolytic treatment performance by periodically removing scales adhering to a cathode plate.

2. Description of the Related Art Conventionally, in order to treat sewage flowing into a sewage treatment plant or the like, an activated sludge method is used in which sewage is introduced into an activated sludge aeration tank and a biological treatment is performed by aeration and agitation.
Excess sludge generated in the water treatment process is usually landfilled after dehydration, but because the disposal site is gradually disappearing, ozone is added to the excess sludge to solubilize the sludge. Attempts have been made to reduce the amount of sludge generated by biodegradation in the system, and in particular, the method of electrolytic treatment of sludge has attracted attention as a method with low processing costs.

  However, when the sludge is subjected to electrolytic treatment as described above, the sludge contains cations such as calcium and magnesium, and is attracted to the cathode plate in the electrolytic cell, and receives electrons and scales on the surface of the cathode plate. Therefore, there is a problem that the electrolysis efficiency is reduced if a large amount of this is accumulated.

  In view of the problems of the above-described conventional sludge electrolysis apparatus, the present invention is capable of maintaining stable electrolysis performance by periodically removing the scale attached to the cathode plate. The purpose is to provide.

  In order to achieve the above object, the sludge electrolysis apparatus of the present invention is a sludge electrolysis apparatus in which a yin-yang electrode plate is immersed in an electrolyzer into which sludge is introduced, so that the cathode plate protrudes above the water. The cathode plate is formed so as to be rotatable about an axis orthogonal to the surface thereof, and a scraping member that slides on the cathode plate and cleans the surface thereof is disposed on the water surface.

  In this case, an air diffuser for ejecting coarse bubbles between the electrodes can be provided in the lower part of the electrolytic cell.

  According to the sludge electrolysis apparatus, in the sludge electrolysis apparatus in which the yin and yang electrode plate is immersed in the electrolyzer into which the sludge is introduced, the cathode plate is formed so that its upper part comes out above the water, and the cathode plate A scraping member that slides on the cathode plate and cleans the surface is disposed on the water surface, so that the surface is scraped off by rotating the cathode plate. By rubbing with a member and scraping off the scale adhered in water, it is possible to prevent a reduction in electrolytic efficiency due to the scale.

  In this case, the sludge scum accumulated between the electrodes can be levitated and discharged by providing a diffuser tube for ejecting coarse bubbles between the electrodes at the lower part of the electrolytic cell.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a sludge electrolytic treatment apparatus of the present invention will be described with reference to the drawings.

In activated sludge treatment using electrolytic treatment, organic sludge is biologically treated with activated sludge in the aeration tank, and sludge generated by biological treatment is sterilized and solubilized, and then this treated sludge is returned to the aeration tank. Disassemble.
In this case, salt water and a small amount of acid are added to the sludge, and electrolysis is performed in the electrolytic cell to sterilize microorganisms in the sludge and solubilize the sludge.
At this time, calcium and magnesium contained in the sludge are attracted to the cathode plate side by electrolytic treatment, get electrons, become a scale of hydroxide etc., adhere to the cathode plate surface, and gradually accumulate. Decreases.

Therefore, the cathode plate in the electrolytic cell is a disk or a square plate and has a structure that can rotate around the central axis, and about 1/2 of the cathode plate protrudes above the water.
Further, a cleaning brush or a scraper is disposed as a scraping member so as to sandwich each cathode plate above the water.
Then, a change in current or voltage due to scale adhesion is detected, or the cathode plate is rotated about 180 degrees automatically or semi-automatically at an appropriate time interval, and the scale adhered in water is scraped off with a cleaning brush. It is possible to prevent the electrolytic efficiency from being lowered.

FIG. 1 shows an embodiment of a sludge treatment flow using the sludge electrolytic treatment apparatus of the present invention.
Sewage flowing into a sewage treatment facility such as a sewage treatment plant is usually biologically treated with activated sludge. At this time, excess sludge is generated by the growth of sludge microorganisms. 1 leads to the electrolytic cell 2.
In addition, although the excess sludge A may guide the sludge settled in the final sedimentation tank to the electrolytic cell 2 as it is, it is also possible to use the sludge concentrated by gravity.
At this time, an electrolytic solution D containing chlorides such as salt and a small amount of acid necessary for electrolysis is injected into the piping in the middle by a chemical injection pump 4, and a line mixer and a stirring water tank are provided to add sludge and electrolytic solution. You may mix.

A plurality of electrode plates are provided inside the electrolytic cell 2.
The cathode plate 20 is formed of a square as shown in FIG. 1 or a disk-like plate as shown in FIG. 2, and protrudes about 1/2 to the water surface, and is connected by a central shaft 20a to be bearings 24 at both ends. It is installed so that it can be rotated.
The anode plate 21 has the same shape as the underwater portion of the cathode plate 20, and a plurality of anode plates 21 are installed between the cathode plate 20 and the cathode plate 20 so as to face the cathode plate 20.

Although not shown in the drawing, a mechanism for rotating the cathode plate 20 from the driving device via a gear or a belt is provided, and for example, a timer or sensor for rotating the cathode plate 20 180 degrees by one rotation operation is provided. Such a mechanism can be provided separately.
As shown in FIG. 2, anode plates 21 and cathode plates 20 are alternately connected from a DC power source 23 to electrodes arranged at a predetermined interval. However, the rotation mechanism and the power feeding method are not particularly limited.

On the other hand, a cleaning brush 22 as a scraping member is provided above the cathode plate 20 so as to sandwich each cathode plate 20, and an air diffuser tube 25 that can eject coarse bubbles under each electrode plate 20, 21. And a predetermined amount of air E can be injected from a blower or the like.
The scraping member is fixed to the electrolytic cell 2 side, and the surface of the scraping member can be rubbed as the cathode plate 20 rotates. As the scraping member, a scraper such as a rubber plate can be provided instead of the cleaning brush 22.

Sludge that overflows from the weir at the end of the electrolysis tank 2 flows into the adjacent defoaming tank 3. The defoaming tank 3 is provided with a surface agitator 30 and crushes the sludge scum by rotating the impeller on the water surface. .
In addition, a pipe is provided for extracting the sludge subjected to the defoaming treatment from the bottom and returning it to the electrolytic cell 2 by the sludge return pump 5. The electrolytically treated sludge C overflowed from the defoaming tank 3 is returned to the aeration tank of the water treatment facility.

Next, the operation of this embodiment will be described.
In order to replenish the chlorine ions necessary for the electrolytic treatment, surplus sludge A injected with an electrolyte containing a chloride such as salt and a small amount of acid by the chemical injection pump 4 is put into the electrolytic cell 2 and is subjected to a direct current. Passes between the electrode plates 20 and 21 through which the gas flows.
At this time, chlorine ions contained in the sludge are converted into hypochlorous acid by electrolysis, and microorganisms in the sludge are sterilized by the strong oxidizing power of hypochlorous acid.
In order to more efficiently generate hypochlorous acid having a high sterilizing power, it is necessary to add about 0.2 to 1% of the sludge weight as chlorine ions as sodium chloride, and the optimum pH is about 4 to 6 Therefore, it is desirable to add a small amount of acid.
The chloride ion to be added is not limited to sodium chloride such as sodium chloride, and a chloride that dissolves in water at a relatively low cost such as potassium chloride can be used.

In this case, the excess sludge contains calcium and magnesium. However, during the electrolytic treatment, the calcium and magnesium are attracted to the cathode plate 20 side to receive electrons and become a scale of hydroxide or the like to form the cathode plate 20. It adheres to the surface of the material and gradually accumulates.
Therefore, the change in resistance between the electrodes accompanying the adhesion of the scale is confirmed by a change in the current value or voltage, or the operation is switched to the scale removal operation at an appropriate time interval.
The cathode plate 20 is gently rotated by operating the driving device with sensing or a timer or by a manual switch.
At this time, the attached scale is scraped off by the cleaning brush 22 or the scraper provided on the upper part of the water. In addition, in order to wash away the scale adhering to the brush or the scraper, it is desirable to provide a separate watering pipe or to spray water manually.
Further, the rotation angle of the cathode plate is not necessarily limited. However, in particular, in the square cathode plate 20 shown in FIG.

On the other hand, in the course of the electrolytic treatment, fine oxygen and hydrogen bubbles are generated in addition to hypochlorous acid, which adheres to the sludge and forms a scum and gradually accumulates between the electrode plates 20 and 21.
Therefore, coarse bubbles are intermittently ejected from the diffuser pipe 25 provided at the lower part of the electrolytic cell 2 to float the sludge scum on the water surface and to generate a circulating water flow.
By this circulation flow, the sludge scum is dispersed throughout the electrolytic cell, and part of the sludge scum overflows from the weir and flows out to the adjacent defoaming tank 3.

In the defoaming tank 3, sludge scum is crushed by the rotation of the impeller of the surface agitator 30. In order to improve the sterilizing effect, a part of the sludge returned from the scum to the liquid state is electrolyzed by the sludge return pump 5. It is also possible to return to 2 and perform electrolytic treatment again.
Moreover, the electrolytically treated sludge C overflowed from the weir of the defoaming tank 3 is returned to the aeration tank of the water treatment system.
Electrolyzed sludge is gradually reduced in molecular weight by sludge microorganisms in the aeration tank because microorganisms are killed by electrolytic treatment, and part of the cell walls and cell membranes constituting the microorganisms are damaged and the cytoplasm in the cells is eluted. Finally, it is decomposed into water and carbon dioxide.

In this way, the sludge electrolytic treatment apparatus of this embodiment can perform the electrolytic treatment while removing the sludge scum accumulated between the scale and the electrodes adhering to the surface of the cathode plate 20, and is thus stable and efficient. Electrolytic treatment can be performed.
In addition, the sludge electrolysis apparatus of the present embodiment guides surplus sludge generated in the activated sludge method to the electrolysis tank 2, and adds chloride and a small amount of acid to perform the electrolysis process stably and efficiently. Therefore, when returned to the aeration tank, the sludge microorganisms killed by the activated sludge are stably oxidized and decomposed, and the amount of sludge discharged to the outside is reduced to about 1/10 of the conventional activated sludge method. Further, since the energy required for the electrolytic treatment can be reduced, the treatment can be performed at an inexpensive running cost.

  The sludge electrolysis apparatus of the present invention has been described based on the examples thereof. However, the present invention is not limited to the configurations described in the above examples, and the configurations described in the examples are appropriately combined. The configuration can be changed as appropriate without departing from the spirit of the invention.

  The sludge electrolytic treatment apparatus of the present invention has a characteristic of maintaining stable electrolytic treatment performance by periodically removing the scale attached to the cathode plate, so that the electrode of the electrolytic treatment apparatus is cleaned. It can use suitably for the use of.

It is sectional drawing which shows one Example of the electrolytic treatment apparatus of the sludge of this invention. It is a side view which shows another shape of the cathode plate used for the electrolytic treatment apparatus of the same sludge. It is a front view which shows the electrolytic treatment apparatus of the sludge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge supply pump 2 Electrolysis tank 3 Defoaming tank 4 Chemical injection pump 5 Sludge return pump 20 Cathode plate 20a Shaft 21 Anode plate 22 Cleaning brush (scraping member)
23 DC power supply 24 Bearing 25 Aeration pipe 30 Surface stirrer A Surplus sludge B Defoamed sludge C Electrolytically treated sludge D Electrolyte E Air

Claims (2)

  In a sludge electrolytic treatment apparatus in which a Yin and Yang electrode plate is immersed in an electrolytic cell for introducing sludge, the cathode plate is formed so that its upper part comes out above the water, and the cathode plate is centered on an axis perpendicular to its surface. A sludge electrolysis apparatus characterized in that a scraping member that is rotatably provided and slidably contacts the cathode plate and cleans the surface thereof is disposed on the water surface.   2. The sludge electrolytic treatment apparatus according to claim 1, wherein a diffuser pipe for ejecting coarse bubbles is provided between the electrodes at a lower portion of the electrolytic cell.

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