JPS6068020A - Electroosmotic dehydrator - Google Patents

Abstract

PURPOSE:To maintain electrical contact of an electrode with sludge in good condition and to perform dehydration at high efficiency by excluding the gas generated at the anode side accompanying to electroosmotic dehydration to the outside by forming a gas discharging passage for excluding the gas in the anode side electrode member. CONSTITUTION:The sludge supplied from a hopper 7 is dehydrated by mechanical compression and electroosmotic effect in a sludge transporting passage 6 between a rotary drum 1 serving also as an anode side electrode member and a pressing belt 2 serving also as a cathode side electrode member. In this stage, electrolysis of water and gasification of chlorine ion are caused in combination with electroosmotic dehydrating effect in the sludge, and gaseous oxygen and gaseous chlorine are generated in the anode side. Therefore, contact of sludge with the electrode becomes inferior, so many holes 17 bored as gas discharging passage are provided penetrating the surface of an electrode segment 16 constituting the rotary drum 1, and generated gas is discharged to the outside through the holes 17.

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]

As an electro-osmotic dehydrator that continuously dehydrates slurry by applying electricity, a structure as shown in FIG. 1 or 2 is known. In FIG. 1, ■ is a metal rotating drum that also serves as an anode side electrode member, and 2 is a metal drum that has a cathode side electrode member stretched across a sprocket 3 facing the circumferential surface of the drum 1. a press belt 4; a filter belt 4 for permeating filtered water stretched over the press belt 2; 5 a belt drive motor;
A slurry conveying passage 6 is formed in the area facing the filter belt 4, and a slurry supply water bath 7 is installed on the entrance side of the slurry conveying passage 4, and these constitute the main body of the dehydrator. . In addition, a belt-type conveyor 8 as a slurry supply means is installed on the person 1'' side toward the hopper 7.
Further, a DC power supply device 9 is connected to the electrode drum 1 on the opposite electrode side with the press belt 2 serving as the cathode electrode being on the ground side. Note that IO is the filtered water tray leading to the outside of the system, 1
1 is a dehydrated cake collection container, and I2 is a drive motor for the conveyor 8. In the example shown in FIG. 1 above, the anode side electrode member is configured as a rotating drum I, whereas in the example shown in FIG. 1ull electrode member 13
The filter belt 4 is placed substantially parallel to and opposite to the filter belt 4 which is stretched along the filter belt 4. The rest of the structure is almost the same as that in FIG. In each of the configurations shown in FIGS. 1 and 2 above, the slurry 14 as a material to be dehydrated is fed from the slurry supply conveyor 8 through the hopper 7 to the slurry conveyance passage 6, and on the other hand, the drive motor 5 is operated, and the slurry If @14 is sandwiched in the conveyance path and conveyed toward the exit in the direction of arrow P, and power is supplied from the power supply 9, the slurry 14 will be formed between the opposing electrodes in addition to the mechanical squeezing force. The applied electric field acts on the water contained in the slurry, which becomes positively charged and flows toward the cathode, where it is discharged to the electrode member and is also transmitted through the filter belt 4 to be dehydrated, so-called electroosmotic dehydration. You will be killed. 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°, and is sent out from the outlet of the passage 6, and is collected into the collection container if through the chute 15. In this way, slurry such as sludge with a high hydrogen content is treated in a continuous manner to reach a moisture content of, for example, 50.
% or less dehydrated cake. This dehydrated cake is 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. allowed to live there. 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 out of the system. , oxygen gas lived on the anode side. The chlorine gas remains trapped between the surface of the anode side electrode member and the slurry and cannot be extracted, forming an electrically insulating gas J- in the core. As a result, it was found that electrical contact between the electrode member on the anode side and the slurry was established, and the electrical conductivity to the slurry was reduced, resulting in no reduction 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 delivered to the anode side during electroosmosis is immediately expelled from the system, thereby maintaining a high electroosmosis effect and preventing electrode corrosion due to the generated gas. It is an object of the present invention to provide an electroosmotic dehydrator, in particular, the structure of its anode side electrode member, which is designed to reduce the amount of water used.

[Key points of the invention]

In order to achieve the above object, the present invention provides an anode side car pole portion H.
A gas venting path is formed in the form of a hole or groove on the plate surface of the plate, and the gas generated on the anode side is removed from the thread outside the gas venting path by placing the gas venting path at 1...1-, -. It is.

[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.
The metal electrode segment 16 constituting the anode side electrode member, which serves as a breather belt, has a large number of holes 17 distributed over the plate surface as gas vent passages. Furthermore, a gas-permeable filter material 18 such as a corrugated cloth is attached to the outer peripheral surface of the electrode member so as to cover the surface of the electrode member. 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 I8, and pass through the gas vent hole 1.
7 will be excluded from the system. This prevents the generated gas from remaining between the rotary drum 1 or press belt I', which also serves as the anode side electrode member, and the slurry conveyed in the slurry conveying passage 6 during dewatering operation, and prevents the gas from remaining in the slurry. Electrical contact with 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, by covering the outer periphery of the anode side electrode member with a filter material 18 such as a filter cloth as in the illustrated embodiment,
The slurry does not come into direct contact with the electrode member, and this prevents the slurry dehydrated and dried by electroosmotic dehydration from forming scale and sticking to the surface of the metal electrode member, thereby inhibiting the electrical conductivity of the slurry. Although the illustrated embodiment shows an example in which the gas vent path is the hole 17, the gas venting path is not limited to the hole, but it is also possible to form a groove leading to the outside of the system in the plate surface of the electrode member. Further, the above-mentioned configuration can be applied not only to the continuous processing method shown in the illustrated example 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, and Figures 3 and 4 are diagrams of embodiments of the present invention corresponding to Figures 1 and 2, respectively. , FIG. 5 is an enlarged sectional view of the main part of the anode side electrode member in FIGS. 3 and 4.

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, the gas generated on the anode side due to electroosmosis is removed from the system through the anode side electrode member. 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 cathode side electrode member is coated with a filter material for gas permeation.