JPS621426A - Electroosmotic dehydration apparatus - Google Patents

Abstract

PURPOSE:To prevent the generation of a gas protrusion phenomenon, by forming a filter chamber held to negative pressure to the back surface side of a filtering surface and positively sucking a filtrate or the gas generated in a substance to be subjected to dehydration treatment by negative pressure acting on the filter chamber to discharge the same out of the system. CONSTITUTION:The side of a filter chamber 11 is held to negative pressure across a filter material 4 and a cathode side electrode 5 by a vacuum pump 14 through a vacuum tank 1 and, because of this, the moisture separated from sludge 10 by electroosmotic action and flowed toward the cathode side electrode 5 is flowed out to the filter chamber 11 by negative pressure acting on the filter chamber 11 and recovered in the vacuum chamber 13. At the same time, the gas such as steam generated during the electroosmotic process is vented to the filter chamber 11 and exhausted to the outside by a vacuum pump 14.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to an electroosmotic dewatering device that dehydrates excess sludge generated in a sewage treatment plant, for example, by electroosmotic action as a material to be dehydrated.

[Prior art and its problems]

2. Description of the Related Art Electroosmotic dewatering apparatuses have been known that apply electroosmotic action to dehydrate materials to be dehydrated, such as sludge. Here, the configuration of a conventional batch processing type electroosmotic dewatering apparatus will be explained with reference to FIG. In FIG. 4, 1 is a dehydration treatment container in the form of a cylinder, 2 is a piston inserted into the cough container, 3 is a driving part of the piston 2, and a filter material 4 such as a filter cloth is provided at the bottom of the container 1. A pole side electrode Bi5 is provided on the hole electrode plate, and an anode side electrode 6 is provided on the inner surface of the piston 2, facing the negative i side electrode 8i5.
In addition, a DC power source 7 is connected between the T-windings 5 and 6. Note that 8 is the material to be dehydrated! 9 is a filtrate outlet. With the above configuration, the sludge 10 as the material to be dehydrated is introduced into the dehydration treatment container l through the supply port 8 with a voltage applied between the t poles 5 and 6, and in this state, the piston 2 is driven to pressurize it. In addition to the mechanical squeezing force caused by pressurizing the piston, an electric field acts on the sludge 10 between the opposing poles 5 and 6, and the water contained in the sludge becomes positively charged due to the electroosmotic action. It flows to the cathode side and is discharged to this electrode, and at the same time, it passes through the filter medium 4 and the through hole of the cathode side electrode pi5 and is discharged out of the system from the filtrate discharge port 9. By the way, in the electroosmotic dewatering device described above, when the water in the sludge 10 flows toward the cathode electrode 5 due to electroosmotic action, the sludge particles act as filtration resistance and prevent the flow of water, so the dewatering efficiency is not high. Separately, due to the heat generated during t8i, part of the moisture contained in the sludge is vaporized to form a gas layer within the sludge. Moreover, gas is generated in such sludge! This not only causes an increase in the current carrying resistance between the electrodes and reduces the electroosmotic effect, but also causes a pressure increase in the sludge, and the gaps that naturally occur inside the sludge during the dewatering process are filled with gas. Gas may suddenly protrude outside as an escape route, but such a phenomenon of high-temperature, high-pressure gas protruding is dangerous from a safety standpoint.

[Purpose of the invention]

This invention has been developed in consideration of the above points, and it solves the above-mentioned conventional difficulties and efficiently discharges the filtrate separated from the material to be dehydrated by electroosmosis to the outside of the system. An object of the present invention is to provide an electroosmotic dehydration device that can effectively degas generated gases such as water vapor generated during operation and prevent the occurrence of gas protrusion phenomenon.

[Key points of the invention]

In order to achieve the above object, the present invention forms a reducing wheel maintained at negative pressure on the back side of the filtration surface in an electroosmotic dehydration device, and the negative pressure acting on the reducing wheel causes the generation in the filtrate and the material to be dehydrated to be reduced. This system actively sucks gas out of the system.

[Embodiments of the invention]

1, 2, and 3 show different embodiments of the present invention. First, FIG. 1 shows an embodiment corresponding to the batch processing method shown in FIG. 4 described above, and the same members corresponding to FIG. 4 are given the same reference numerals. That is, according to the present invention, a filter medium 4 is provided on the bottom side of the dehydration treatment container 1. Behind the cathode side f8i5, a reducing wheel indicated by reference numeral 11 is defined, and the reducing wheel 11 is connected via a drain pipe 12 to a vacuum tank 13 for collecting filtrate. Note that 14 is a vacuum pump connected to the vacuum tank 13, and 15 is a drain valve for discharging filtrate. When performing dehydration processing, the drain valve 15 is closed and the vacuum pump 14 is operated to connect the vacuum tank 13 and the drain valve 15. The inside of the reduced vehicle 11 is maintained at negative pressure. According to the above configuration, the number of vehicles reduced by 1 at the border of the filter medium 4 and the electrode 5 is
Since the 1 side is maintained at negative pressure, the water that separates from the sludge 10 by electroosmosis and flows toward the negative electrode 5 is the i! of the sludge particles. ! The suction force of the negative pressure acting on the reducing wheel 11 causes the water to be emptied by the suction force of the negative pressure acting on the reducing wheel 11 without being affected by excessive resistance, and forcibly flows out to the reducing wheel 11, from where it is collected in the vacuum tank 13 via the drain pipe 12. At the same time electric immersion
The generated gases such as water vapor generated in the sludge in the step 3 are also degassed by the negative pressure action in the reducing vehicle 11 without being stagnated in the sludge or suddenly protruding to the outside. Note that this gas is recovered in the -H vacuum tank 13 and then exhausted to the outside through the vacuum pump 14. This solves the problems with the conventional configuration described in Figure 4,
It is possible to improve dewatering efficiency and safety in terms of safety. FIG. 2 shows an example of a continuous processing type belt conveyance type electroosmotic dehydrator, in which a press belt 16 that also serves as an anode electrode is placed between the press belt 16 and the sludge. A filter belt 18, a belt drive motor 19, and a sludge supply hopper 2 facing each other across a passage 17.
0, cathode side electrode 5 installed on the back side of the filter belt 18
, and the cathode side bracelet 16 and the cathode side electrode 5
It is composed of a power source 7 and the like that applies a voltage between the two. Note that 21 is a dehydrated cake of sludge that has been dehydrated, and 22 is a collection container for the dehydrated cake. With this configuration, the sludge 10 is continuously supplied from the supply hopper 2o into the sludge passage 17, and the press belt 16 and filter belt 18 1! During the conveyance process in which it is conveyed in the direction of arrow P while receiving a squeezing force between it! Electricity is passed between the electrodes to cause electroosmotic dehydration, whereby the water contained in the sludge passes through the filter belt 18 and the through holes of the cathode side electrode 5 and is separated and dehydrated. Here, according to the present invention, a reducing wheel 11 is installed behind the cathode side electrode 5, and the reducing wheel 11 in parentheses is connected to a vacuum tank 13 in the same way as described in FIG.
is connected to. Therefore, by operating the vacuum pump 14 to maintain the inside of the filter chamber 11 at a negative pressure during the electroosmotic dewatering process, the filtrate separated from the sludge and the gas generated in the sludge are removed as in the embodiment shown in FIG. It can be effectively sucked up and removed from the system. FIG. 3 shows yet another embodiment, in which the same or equivalent members corresponding to those in FIG. 2 are given the same reference numerals. That is, in this embodiment, a ring-shaped cathode side electrode 5 is installed on the outer periphery of the rotating drum, and a filter belt 18 is stretched over the outer periphery of this electrode. On the other hand, on the inner peripheral surface side of the cathode side electrode 5, a filter chamber 11 which communicates with a vacuum tank 13 via a drain pipe 12 is divided and defined inside the drum. The drum assembly has a lower circumferential area immersed in a sludge tank 23 containing low-concentration sludge 1O, and a press belt 16 facing the upper circumferential area of the drum that also serves as an anode. is in place. Vacuum pump 14 connected to vacuum tank 13 with such a configuration
If the drum is rotated in the direction of the arrow while maintaining each filter chamber 11 in the drum at a negative pressure, sludge will be deposited on the filter belt 18 in the zone passing through the sludge tank 23. Adsorbed in tN tKA form. Further, the sludge deposited on the filter belt is conveyed by the belt, and in the process of passing between it and the press belt 16, it is subjected to an electroosmotic action. This causes the filtrate to flow through the filter belt 18. The water passes through the through hole of the electrode 5 and is suction-filtered to the filtration chamber 11 which is maintained at negative pressure, and from there is collected into the vacuum tank 13 through the drainage gap 12. At the same time, generated gases such as water vapor generated in the sludge are also degassed from the sludge and suctioned away to the vacuum tank side, as in the previous embodiment.

【Effect of the invention】

As described above, according to the present invention, a filtration chamber maintained at negative pressure is formed on the back side of the filtration surface in an electroosmotic dehydration device, and mito air generated in the filtrate and the material to be dehydrated is passed through the cough filtration chamber. By sucking and discharging generated gases from the system, it is possible to efficiently dehydrate the filtrate that is separated from the material to be dehydrated and flows toward the filtration surface by electroosmotic dehydration. It is possible to obtain an electroosmotic dehydration apparatus with high dehydration efficiency and safety, such as being able to remove gases such as water vapor generated in the object to be dehydrated during treatment.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views of different embodiments of the present invention, and FIG. 4 is a cross-sectional view of a conventional batch processing type electroosmotic dehydrator. Filter medium, 5: cathode side electrode, 6: positive side electrode, 7: power source, 10: sludge as a material to be dehydrated, 11: filter chamber, 13
: Vacuum tank for filtrate collection, 14: Vacuum bong 1st factor Figure 3 Figure 40

Claims (1)

[Scope of Claims] 1) An electroosmotic dehydration apparatus in which a material to be dehydrated is supplied between opposing electrodes, and the water in the material to be dehydrated is separated and dehydrated by passing through a filtration surface by electroosmotic action. An electroosmotic dehydration apparatus characterized in that a filter chamber maintained at negative pressure is formed on the back side of the surface, and the filtrate and the gas generated inside the material to be dehydrated are suctioned and discharged outside the system through the filter chamber. . 2) The electroosmotic dehydration apparatus according to claim 1, characterized in that a vacuum tank for filtrate recovery is connected to the filtration chamber.