JPH0433484B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention uses, for example, excess sludge generated in sewage treatment plants, or sludge of slurry-like substances generated in food and other industrial fields as a material to be dehydrated, and the dewatered material is subjected to electricity treatment. This invention relates to an electroosmotic dehydrator that performs dehydration through osmosis. [Prior Art] Regarding the above-mentioned electroosmotic dewatering machine, various types are disclosed in, for example, Japanese Patent Application Laid-Open No. 60-25597. An overview of the configuration of a continuous process type electroosmotic dehydrator will be explained. In the figure, 1 is a rotating drum having an anode side electrode 1a made of a material with high resistance to electrolytic corrosion adhered to its outer peripheral surface, and the rotating drum 1 is supported by a mount (not shown) via a bearing. ing. Further, a filter belt 2 with an endless structure faces a part of the circumference of the rotating drum 1, and a metal press conveyor 3 with a caterpillar structure, which also serves as a cathode electrode and overlapped with the filter belt 2, is installed between the sprockets 4a to 4d. A slurry squeezing passage 5 is defined between the filter belt 2 and the opposing surface of the rotating drum 1, in which the gap between the electrodes gradually decreases from the inlet to the outlet. Further, below the sludge pressing passage 5 via the filter belt 2 and the press conveyor 3, a filtrate receiving tray 6 is installed which communicates with a drainage channel outside the system. Here, a drive motor 7 is transmission-coupled to the sprocket, and a sludge supply hopper 8 is provided on the inlet side of the slurry squeezing passage 5, and a sludge dewatering case is separated and collected on the outlet side facing the filter belt 2. A scraper 9 is provided, and a press device 10 is provided along the circumferential surface of the press conveyor 3 in an area behind the slurry squeezing passage 5 with respect to the press conveyor 3. Note that 11 is a bolt for adjusting the mounting position of the press device 10, and 12 is a hydraulic cylinder. On the other hand, a DC power supply 1 is connected via a power supply brush 13 between the power supply slip ring 1b attached to the shaft end of the rotating drum 1 and the support shaft of the sprocket 4a which is in contact with the press conveyor 3, which is the cathode side electrode.
4 are connected. With the above configuration, the drive motor 7 is rotated, and a DC voltage is applied between the anode side electrode and the cathode side electrode from the power supply device 14, and the material to be dehydrated is transferred into the slurry squeezing passage 5 through the hopper 8. When the slurry 15 is supplied, the slurry 15 is conveyed in the direction of arrow P toward the exit side in the sludge pressing passage while being sandwiched between the rotating drum 1 and the filter belt 2, and in this conveyance process, the slurry 15 is In addition to the mechanical squeezing force, an electroosmotic effect is applied due to the electric field formed between the opposing electrodes. Due to this electroosmotic action, the suspended particles in the sludge 15 receive a force that moves them toward the anode under a DC electric field, whereas the water contained in the sludge 15 is positively charged and flows toward the cathode, and the water contained in the sludge 15 is positively charged and flows toward the cathode. The compressing force is also applied, the filter belt 2 passes through the filter belt 2, the water is dehydrated and filtered, and then the press conveyor 3
The filtered water flows down to the drain tray 6 from a drainage channel formed on the plate surface and is drained out of the system. On the other hand, the slurry 15 that has been dehydrated in the passage 5 has a low water content and is turned into a cake, and the dehydrated cake 16 is separated and collected from the outlet side of the passage 5 via a scraper 9, and is incinerated.
Or it can be composted and reused as fertilizer. [Problems to be Solved by the Invention] By the way, when sewage sludge or the like is dehydrated using the electroosmotic dehydrator having the above configuration, the following problems arise as the operation progresses. In other words, when sludge generated in a sewage treatment plant was used as a dewatering object and the electroosmotic dehydrator was operated for dehydration, a white solid substance was deposited on the surface of the press conveyor, which is the cathode side electrode, as the operating time progressed. , and this solid material was observed to be deposited in layers. Moreover, as the amount of solid matter adhering increases, the power consumption of the electroosmotic dewatering machine increases, and the drainage channel of the press conveyor becomes clogged with the adhering material, making it difficult to drain the filtrate smoothly. It was confirmed that the dehydration efficiency was significantly reduced. Therefore, the inventor collected the above-mentioned white product and analyzed its chemical components using a fluorescent X-ray analyzer, and obtained quantitative analysis results as shown in the following table.

【table】

[Means for solving problems]

In order to solve the above problems, according to the present invention, a slurry as a material to be dehydrated is placed between an anode side electrode and a cathode side electrode, which faces the anode electrode and has a filtration member superimposed on its surface. By applying a DC voltage between the anode side electrode and the cathode side electrode, the water contained in the slurry is collected on the cathode side by electroosmosis,
In an electroosmotic dehydrator, the filtrate is separated and drained by passing through the filtration member and the cathode side electrode, and the dehydrated cake deposited on the filtration member is removed by a cake removing means. Providing a section separated from the cathode side electrode,
The section is provided with a means for removing deposited substances deposited on the filtering member side surface of the cathode side electrode. [Function] In the above configuration, the adhering substance removing means is, for example, a brush-type scraper that mechanically removes the adhering substances, a high-pressure water cleaning device, an ultrasonic cleaning device, a chemical cleaning device, etc. The solid adhesion substance generated on the surface of the cathode side electrode is removed by operating the unit as needed. Therefore, the cathode side electrode can be used in a clean state with almost no deposits of deposits, and as a result, the electroosmotic dehydrator can be operated with high dehydration efficiency at all times. [Embodiment] Fig. 1 is an overall configuration diagram of an electroosmotic dehydrator according to an embodiment of the present invention, and Fig. 2 shows a brush-type scraper disposed opposite to the cathode side electrode as a means for removing adhered substances. Identical parts corresponding to FIG. 3 are given the same reference numerals. In other words, the basic structure of the electroosmotic dewatering machine is similar to that shown in Fig. 3, but the length of the filter belt 2 is longer than that of the press conveyor 3, and the length of the filter belt 2 is longer than that of the press conveyor 3. The filter belt 2 is separated from the press conveyor 3 by an auxiliary pulley 1.
7 and 18, and in this separation section, a high-pressure water injection nozzle 19 and a brush-type scraper 20 are arranged facing each other on the surface of the press conveyor 3, that is, on the electrode surface side facing the sludge side. Here, the high-pressure water injection nozzle 19 is installed to inject high-pressure water toward the surface of the press conveyor 3, and one brush-type scraper 20 is installed on the base 20 as shown in FIG.
The press conveyor 3 has a structure in which a bundle of wires 20b made of stainless steel, for example, is implanted in the press conveyor 3, and the wires 20b are placed in contact with the surface of the press conveyor 3. In this configuration, as the electroosmotic dehydrator operates, a white solid substance containing a large amount of calcium hydroxide is generated and adhered to the surface of the press conveyor 3, which is the cathode side electrode, as described above. As the press conveyor 3 rotates, the substance is scraped off by the brush-type scraper 20 described above, and is discharged by jetting high-pressure cleaning water. The press conveyor 3 is therefore moved again in a clean state free of deposits to the area of the sludge squeezing channel 4, where it takes part in the electroosmotic dewatering action as a cathode electrode. As a result, in the area of the sludge squeezing passage 4 where electroosmotic dehydration is performed, the press conveyor 4 maintains a high current-carrying function as a cathode side electrode in a clean state, and at the same time directs the filtrate that has passed through the filter belt 2 to the filtrate receiving tray 6. Drainage can be done smoothly. In addition to the brush-type scraper and high-pressure water jet nozzle employed in the illustrated embodiment, as a means for removing adhered substances, an ultrasonic transmitter equipped with a cleaning liquid such as water or chemicals on the circumference of the press conveyor 3 is used. An ultrasonic cleaning device is equipped with a cleaning tank, and a press conveyor is passed through the cleaning tank to remove substances adhered to the electrode surface by the cavitation action of ultrasonic waves.
A cleaning tank filled with a chemical solution such as a 10-fold diluted hydrochloric acid solution is installed, and by passing it through a press conveyor inside the cleaning tank, substances adhering to the electrode surface, especially calcium hydroxide, which is its main component, are dissolved and removed. It is also possible to employ a chemical cleaning device or the like designed to do this. Furthermore, although the above embodiment shows an example of application to a pressure drum type electroosmotic dehydrator, a belt press type electroosmotic dehydrator uses an endless press belt as the anode side electrode instead of the rotating drum in the illustrated embodiment. Of course, the same method can be applied to a dehydrator. [Effects of the Invention] As described above, according to the present invention, an electroosmotic dehydrator is provided with a section separating the filtration member from the cathode side electrode, and within this section, the surface of the cathode side electrode on the filtration member side is By being configured with a means for removing adherent substances that are deposited and generated on the surface of the cathode side electrode, it is possible to maintain a clean state by removing the adhered substances that are generated on the surface of the cathode side electrode as the electroosmotic dehydrator is operated.
This allows the electroosmotic dehydrator to operate with high dewatering efficiency by preventing unnecessary increases in power loss and deterioration of the filtrate drainage function.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an electroosmotic dehydrator according to an embodiment of the present invention, Fig. 2 is a perspective structural diagram of a brush-type scraper exemplified as a deposit removal means in Fig. 1, and Fig. 3 is a conventional electroosmotic dehydrator. FIG. 1 is an overall configuration diagram of a type dehydrator. In each figure, 1... Rotating drum, 1a... Cathode side electrode, 2...
... Filter belt, 3 ... Press conveyor that also serves as a cathode side electrode, 4 ... Sludge squeezing passage, 14 ... DC power supply, 15 ... Sludge, 16 ... Dehydrated cake, 1
9...High pressure water jet nozzle, 20...Brush type scraper.

Claims (1)

[Scope of Claims] 1. A slurry serving as a dehydration treatment portion is supplied between an anode side electrode and a cathode side electrode which faces the anode side electrode and has a filtration member superimposed on its surface, and the anode side By applying a DC voltage between the electrode and the cathode side electrode, the water containing the slurry is collected on the cathode side by electroosmosis, and from there, it passes through the filtration member and the cathode side electrode to separate and drain the filtrate. In an electroosmotic dehydrator in which a dehydrated cake deposited on a member is removed by a cake removing means, a section is provided to separate the filter member from the cathode side electrode, and within the section, the filter member is separated from the cathode side electrode. An electroosmotic dehydrator characterized by being equipped with a means for removing deposited substances deposited on the surface of a filter member. 2. The electroosmotic dehydrator according to claim 1, wherein the means for removing adhered substances is a brush-type scraper that is placed in contact with the electrode surface to mechanically remove the adhered substances. Osmotic dehydrator. 3. The electroosmotic dehydrator according to claim 1, wherein the means for removing adhered substances is a high-pressure water cleaning device that sprays high-pressure water onto the electrode surface to remove the adhered substances. Type dehydrator. 4. The electroosmotic dehydrator according to claim 1, wherein the means for removing adhering substances is an ultrasonic cleaning device that removes adhering substances from the electrode surface by the cavitation action of ultrasonic waves. Type dehydrator. 5. The electroosmotic dehydrator according to claim 1, wherein the means for removing adhering substances is a chemical cleaning device that dissolves and removes adhering substances on the electrode surface using a chemical.