JPH0747095B2 - Electro-osmotic dehydrator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electroosmotic dehydrator for dehydrating sludge such as excess sludge generated in a sewage treatment plant.

[Conventional technology]

As the electroosmotic dehydrator described above, a batch press type filter press dehydrator as shown in FIG. 3 is known. In the figure, reference numeral 1 denotes a sludge treatment container comprising a combination of a square-shaped filter plate 2 and a press filter plate 3 arranged on the open end face side thereof, a sludge supply port 1a is provided at the top thereof, and a drainage discharge port is provided at the lower part thereof.
1b is open. Further, the anode plate 4 is provided on the inner side surface of the filter plate 2.
However, a squeezing diaphragm 5 is provided on the side of the squeezing filter plate 3 facing the anode plate 4, and a compressed air introduction port 1c is opened behind the diaphragm 5.

Further, with respect to the sludge treatment container 1, on the side facing the anode plate 4, a movable cathode conductive belt 6 extending over the inside and outside of the container, and a filter cloth belt 7 are laid on the inner surface of the diaphragm 5 in an overlapping manner. Has been done. These belts 6 and 7 are endless belts, and pulleys are provided outside the sludge treatment container 1.
It is stretched between 8, 9 and 10, and has a filter plate 2 and a press filter plate 3.
Through the inside and outside of the sludge treatment container 1.
Here, the cathode conductive belt 6 is made of, for example, a flexible thin metal belt or a conductive carbon fiber fabric, while the filter cloth belt 7 is made of a fabric such as nylon or tetron. There is.

Further, 11 is a belt drive motor coupled to the pulley 8, 12 is a pressurizing device for opening and closing the sludge treatment container 1, 13 is a DC power source for applying a voltage between the anode plate 4 and the cathode conductive belt 6, and 14 is a collector. It is an electric brush. Although not shown, cleaning nozzles, scrapers and the like for removing adhered matters from the belts are provided along the moving paths of the belts 6 and 7.

Next, the operation of the electroosmotic dehydrator having the above structure will be described. First, the sludge treatment container 1 is closed by operating the pressurizing device 12, and at the same time, the cathode conductive belt 6 and the filter cloth belt 7 are pressed between the peripheral portions of the filter plate 2 and the press filter plate 3 so as to prevent liquid leakage. Hold it. In this state, sludge 15, which is a substance to be dehydrated, is introduced into the processing container 1 through the sludge supply port 1a, and the anode plate 4 and the cathode conductive belt 6 are
When a DC voltage is applied from the power source 13 to the sludge 15, an electroosmotic action is exerted on the sludge due to the action of the electric field formed between the anode plate 4 and the cathode conductive belt 6 that face each other with the sludge 15 in between, and The contained water permeates the filter cloth belt 7 and collects on the surface of the cathode conductive belt 6.
It flows down along the water guide groove formed on the surface of the drainage outlet 1b.
Is discharged outdoors. In addition, the diaphragm 5 expands by blowing pressurized air behind the diaphragm 5 through the pressurized air inlet 1c as the electroosmotic dehydration progresses, and the cathode conductive belt 6 and the filter cloth belt 7 are directed toward the anode plate 4. The sludge 15 is pressed toward and the pressing force is applied to the sludge 15. As a result, electroosmotic dehydration proceeds more effectively, and the sludge is dehydrated to a low water content.

When the dehydration process is completed once, the processing container 1 is opened to remove the caked sludge, and the cathode conductive belt 6 and the filter cloth belt 7 are circularly moved by the operation of the drive motor 11 to remove the previous treatment. Residual deposits on the belt generated in the process are cleaned and removed, and the clean surface area of the belt is drawn into the processing container in preparation for the next dehydration process.

[Problems to be Solved by the Invention]

By the way, in the electroosmotic dehydrator described above, from the long-term operation record, it has been recognized that the cathode conductive belt 6 is frequently broken in a relatively short period of time due to repeated dehydration treatment steps.

When the inventors investigated the cause of this point, it was found that the reason was as follows. That is, when the cathode conductive belt 6 and the filter cloth belt 7 are sandwiched and fixed between the filter plate 2 and the press filter plate 3 of the sludge treatment container 1, when the diaphragm 5 is pressed from behind, the diaphragm 5 is pushed by the diaphragm 5. The belts 6 and 7 are forced to deform only in the free surface area inside the container. In this case, the filter plate belt 7 made of a fiber woven fabric such as nylon has elasticity and has a high durability against an extension force, and even if it is extended by about several percent, it returns to its original state when the pressing force disappears. . On the other hand, in the cathode conductive belt 6 made of a plastic material having low elasticity such as metal or carbon fiber, the material is fatigued by the repeated load of the stretching force, and finally the fatigue fracture occurs and the belt is broken. .

The present invention has been made in view of the above points, and prevents the occurrence of troubles such as breakage of the cathode conductive belt even by repeating the diaphragm pressurizing operation in the dehydration treatment step, and makes it possible to improve its durability. An object is to provide a structure of an electroosmotic dehydrator.

[Means for Solving the Problems]

In order to solve the above problems, in the electroosmotic dehydrator of the present invention, the cathode conductive belt is slidably drawn to the outside of the sludge treatment container through a drawer portion that penetrates the upper side and the lower side of the sludge treatment container, In the section separated from the filter cloth belt outside the sludge treatment container, it is stretched via a fixed pulley and a movable pulley that gives a constant tension to the cathode conductive belt.

[Action]

With the above configuration, the cathode conductive belt is for the sludge treatment container,
It is slidably drawn around the drawer part that penetrates the container, and a tension pulley is installed in the middle of the belt so that it can be freely displaced in the sludge treatment container by the pressure operation of the diaphragm. It is stretched to apply tension.

As a result, when the cathode conductive belt receives a pressing force from the back surface due to the pressing operation of the diaphragm in the dehydration process, the belt is not stretched and deformed forcibly, and the belt itself is moved into the processing container by the expansion of the diaphragm. You will be drawn in. Therefore, there is no fear that an excessive internal stress will be applied to the cathode conductive belt, and it is possible to avoid the trouble that the belt breaks even if the dehydration treatment process is repeated.

〔Example〕

1 and 2 show the structure of an embodiment of the present invention, and the same members corresponding to FIG. 3 are designated by the same reference numerals.

That is, the basic structure of the electroosmotic dehydrator is the same as that of the conventional one described in FIG. 3, but the cathode conductive belt 6 is stretched around the sludge treatment container 1 without binding. The difference is that it is mounted. For this reason, the cathode conductive belt 6 is provided outside the sludge treatment container 1 in the area outside the filter cloth belt 7.
Separated from the above, it is stretched between the guide pulleys 16, 17, 18 and the tension pulley 19, and slides on the sludge treatment container 1 through belt holes 3a, 3b opened at the upper and lower ends of the squeeze filter plate 3. It is laid so that it can penetrate freely. Also,
An air cylinder 20, for example, is connected to the tension pulley 19 so as to apply a constant tension to the cathode conductive belt 6 in this stretched state. Regarding the filter cloth belt 7, as in FIG. 3, the portion penetrating the sludge treatment container 1 is sandwiched between the peripheral edges of the filter plate 2 and the press filter plate 3.

With this configuration, the diaphragm 6 is used in the dehydration process of the sludge 15.
When pressurizing and applying compressive force to the sludge 15 inside the container,
In the sludge treatment container 1, the free surface area of the filter cloth belt 7 is forcibly stretched and deformed, whereas the cathode conductive belt 6 is not stretched and deformed by force, and the belt 6 is driven by the expansion and deformation of the diaphragm 5. Is drawn into the container through the belt holes 3a and 3b, and the displacement is absorbed by the movement of the tension pulley 19 arranged in the middle of the belt.

Therefore, even if the cathode conductive belt 6 is made of a material with low elasticity such as metal or carbon fiber, excessive tensile stress is not applied to the belt itself, which causes plastic deformation and fatigue fracture. Can be prevented from breaking.

〔The invention's effect〕

Since the electroosmotic dehydrator according to the present invention is configured as described above, it has the following effects.

(1) When pressure is applied to the diaphragm in the sludge dewatering process, the cathode conductive belt itself moves only in accordance with the expansion deformation of the diaphragm, and excessive tensile stress is applied to the cathode conductive belt. There is no.

(2) Therefore, even if the dehydration treatment step is repeated,
It is possible to prevent troubles such as breakage of the cathode conductive belt and greatly improve durability and reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing the construction of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II--II in FIG. 1, and FIG. 3 is a sectional view showing the construction of a conventional filter press type electroosmotic dehydrator. In the figure, 1: Sludge treatment container, 1a: Sludge supply port, 1b: Drainage discharge port, 3a, 3
b: Belt hole, 4: Anode plate, 5: Diaphragm for compression, 6: Cathode conductive belt, 7: Filter cloth belt, 13: DC power supply, 19: Tension pulley.

Claims (1)

[Claims] 1. A sludge treatment container having an anode plate and a squeezing diaphragm facing each other on both sides inside the container, and a movable cathode conductive belt extending over the inside and outside of the sludge treatment container on the surface of the diaphragm, and a filter cloth belt. In the electroosmotic dehydrator laid by overlapping, the cathode conductive belt,
The sludge treatment container is slidably routed to the outside of the sludge treatment container through a pull-out portion that penetrates the upper side and the lower side of the sludge treatment container, and a fixed pulley and this cathode are provided in a section separated from the filter cloth belt outside the sludge treatment container. An electro-osmotic dehydrator, which is stretched via a movable pulley that gives a constant tension to a conductive belt.