JPS6345605B2 - - Google Patents

Description

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

The present invention relates to an electroosmotic dewatering machine that dehydrates slurry such as sludge produced in a sewage treatment plant and turns it into a cake.

[Prior art and its problems]

An electroosmotic dehydrator having a configuration as shown in FIG. 1 or 2 is known as an electroosmotic dehydrator that continuously dehydrates slurry by applying electroosmosis. In FIG. 1, 1 is a metal rotating drum that also serves as an anode side electrode member, and 2 is a metal rotating drum that also serves as a cathode side electrode member that is stretched across a sprocket 3 facing the circumferential surface of the drum 1. a press belt; 4 is a filter belt for permeating filtered water stretched over the press belt 2; 5 is a belt drive motor;
A slurry conveying passage 6 is defined in the area facing the filter belt 4, and a slurry supply hopper 7 is installed on the entrance side of the slurry conveying passage 4, and these constitute the main body of the dehydrator. A belt-type conveyor 8 as a slurry supply means is installed on the inlet side of the hopper 7, and the press belt 2, which also serves as an anode electrode, is connected to the electrode drum 1 on the other electrode side as the ground side. is connected to the DC power supply device 9. Note that 10 is a filtered water tray leading to the outside of the system, and 11
12 is a dehydrated cake collection container, and 12 is a drive motor for the conveyor 8. In the example shown in FIG. 1, the anode side electrode member is configured as a rotating drum 1, whereas in the example shown in FIG. The filter belt 44 is disposed substantially parallel to and opposite to the filter belt 44 stretched along the side electrode member 13 . The rest of the structure is almost the same as that in FIG. In each of the configurations shown in FIG. 1 and FIG.
At the same time, the drive motor 5 is operated to feed the slurry 14 as a material to be dehydrated.
When the slurry 14 is sandwiched like a sandwich in the conveyance passage and conveyed toward the exit in the direction of arrow P, and power is supplied from the power supply 9, the slurry 14 is formed between the opposing electrodes in addition to the mechanical squeezing force. When an electric field is applied, the water contained in the slurry becomes positively charged and flows toward the cathode, and is discharged to this electrode member, and at the same time, it passes through the filter belt 4 and is dehydrated, so-called electroosmotic dehydration. become. The filtrate that has passed through the filter belt 4 drips into the filtrate tray 10, from which it is drained out of the system. On the other hand, the dehydrated slurry is turned into a cake, becomes a dehydrated cake 14', is sent out from the outlet of the passage 6, and is collected into the collection container 11 via the chute 15. In this way, slurry such as sludge with a high water content is continuously dehydrated and becomes a dehydrated cake with a water content of 50% or less, for example. This dehydrated cake can be incinerated or composted and reused as fertilizer. By the way, when the electroosmotic dehydration treatment described above is performed on sludge etc. generated at a sewage treatment plant as the material to be dehydrated, electrolysis of water and gasification of chlorine ions in the slurry occur in addition to the electroosmotic dehydration effect. It is recognized that this occurs. For this reason, hydrogen gas is generated on the cathode side, and oxygen gas and chlorine gas are generated on the anode side. In this case, in the structure of the conventional machine shown in Figs. 1 and 2, the hydrogen gas generated on the cathode side passes through the filter belt 4 shown in the figure together with the filtered water and is discharged to the outside of the system. Oxygen gas and chlorine gas generated on the anode side are trapped between the surface of the anode side electrode member and the slurry and remain without being able to escape, forming an electrically insulating gas layer in the area. do. As a result, it was found that the electrical contact between the electrode member on the anode side and the slurry deteriorated, resulting in a decrease in electrical conductivity to the slurry, resulting in a decrease in the electroosmotic dehydration ability. Moreover, metal electrode members are subject to corrosion by oxygen and chlorine gas.

[Purpose of the invention]

This invention was developed in consideration of the above points, and the gas generated on the anode side due to electroosmosis is immediately expelled from the system, thereby maintaining a high electroosmosis effect and reducing electrode corrosion caused by the generated gas. It is an object of the present invention to provide an electroosmotic dehydrator, in particular, the configuration of an anode side electrode member thereof.

[Key points of the invention]

In order to achieve the above object, the present invention forms a gas venting path in the form of a hole or groove on the plate surface of the anode side electrode member, so that gas generated on the anode side can be immediately removed from the system through the gas venting path. This is what I did.

[Embodiments of the invention]

3 and 4 show different embodiments of the present invention corresponding to FIGS. 1 and 2, respectively, and FIG. 5 shows the detailed structure of the anode side electrode member in each embodiment. Or press belt 1'
The metal electrode segment 16 constituting the anode side electrode member is provided with a large number of holes 17, which are distributed throughout the plate surface and serve as degassing passages. Further, a gas-permeable filter material 18 such as a filter cloth is superimposed on the outer circumferential surface of the electrode member to cover the surface of the electrode member. According to the above configuration, oxygen gas and chlorine gas generated on the anode side by electroosmosis during the slurry dehydration process are immediately separated from the slurry, permeate through the filter material 18, and are exhausted to the outside of the system through the gas vent hole 17. will be done. This prevents generated gas from remaining stagnant between the rotating drum 1 or press belt 1', which also serves as the anode side electrode member, and the slurry conveyed in the slurry conveying passage 6 during dehydration operation. Electrical contact between the slurry and the electrode member is maintained well. Therefore, good electrical conductivity to the slurry can be maintained and efficient electroosmotic dehydration can be performed. Further, by eliminating the generated gas, the contact time between the gas and the electrode member is reduced accordingly, so that the degree of corrosion is reduced. In addition, as in the illustrated embodiment, a filter material 18 such as a filter cloth is attached to the outer periphery of the anode side electrode member, so that the slurry does not come into direct contact with the electrode member, and as a result, electroosmotic dehydration can be carried out. It is possible to prevent the dehydrated and dried slurry from turning into scale and sticking to the surface of the metal electrode member, thereby inhibiting electrical conductivity to the slurry. Although the illustrated embodiment shows an example in which the gas vent passage is a hole 17, the present invention is not limited to a hole, but a groove leading to the outside of the system may be formed in the plate surface of the electrode member. Furthermore, the above-mentioned configuration can be applied not only to the continuous processing method shown in the drawing, but also to a batch processing method electroosmotic dehydrator to obtain similar effects.

【Effect of the invention】

As described above, according to the present invention, gases such as oxygen and chlorine generated on the anode side due to electroosmotic dehydration of slurry are immediately removed by forming a gas vent path for eliminating generated gas in the anode side electrode member. By removing it from the system, it is possible to maintain good electrical contact between the electrode and the slurry, thus maintaining high electrical conductivity, thereby realizing highly efficient electroosmotic dehydration operation.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams of different types of conventional electroosmotic dehydrators, respectively.
4 is a configuration diagram of an embodiment of the present invention corresponding to FIGS. 1 and 2, respectively, and FIG. 5 is an enlarged cross-sectional view of the main part of the anode side electrode member in FIGS. 3 and 4. . DESCRIPTION OF SYMBOLS 1, 1'...Rotating drum and press belt that also serves as an anode side electrode member, 2...Press belt that also serves as a cathode side electrode member, 4...Filtering material, 6...Sludge transport path as a slurry passage, 9 ...Power supply device, 10
... Drainage tray, 13 ... Cathode side electrode member, 14 ...
...sludge, 17...pores as gas vents, 18...
...Gas-permeable filter media.

Claims (1)

[Claims] 1. A voltage is applied between an anode and a cathode side electrode member arranged opposite each other, and the water contained in the slurry supplied to the slurry passage between the electrodes is transferred to the cathode side by electroosmotic action. In an electroosmotic dehydrator that collects water and drains it out of the system through a filter material for permeating filtrate, the gas generated on the anode side due to electroosmosis on the anode side electrode member is removed from the system. An electroosmotic dehydrator characterized by forming a gas venting path of holes or grooves. 2. An electroosmotic dehydrator according to claim 1, characterized in that the surface of the anode side electrode member is coated with a filter material for gas permeation.