JP5341691B2 - Filter cloth for belt press type electroosmotic dehydrator - Google Patents

Description

  The present invention relates to a filter cloth used in a belt press type electroosmotic dehydrator.

  First, an outline of a belt press type electroosmotic dehydrator which is an object of an embodiment of the present invention will be described with reference to FIG.

  In FIG. 4, 1 is a rotating drum having a conductive material on its peripheral surface, 2 is an endless press belt stretched around guide rolls 3a to 3e so as to surround a part of the peripheral area of the rotating drum 1, An endless filter cloth belt laid on the peripheral surface of the press belt 2 is a DC power source for applying a voltage between the electrodes, with the rotary drum 1 as an anode and the press belt 2 as a cathode. Part. Further, a sludge passage is defined in a surface area where the rotary drum 1 and the press belt 2 are opposed to each other.

  An electroosmotic dehydrator having such a configuration is known, for example, in Patent Document 1 and the like, and a voltage is applied between the rotating drum 1 and the press belt 2 and the press belt 2 is moved around by a drive motor (not shown). When the sludge, which is the material to be dewatered, is supplied to the sludge passage, the sludge is sandwiched between the rotary drum 1 and the press belt 2 and conveyed while receiving mechanical squeezing force, and at the same time formed between the counter electrodes. It receives electroosmotic action by electric field.

  Due to this electroosmotic action, the water contained in the sludge is positively charged and collected on the cathode side. From there, it passes through the filter cloth belt 4 and the press belt 2 and flows down to the drainage receiving portion 6 and is discharged out of the system as waste water. Is done. On the other hand, the sludge is converted into a dehydrated cake having a low water content by the above dehydration, and is separated and recovered by the scraper 7 that contacts the surface of the filter belt 4 on the outlet side of the sludge passage. Reference numeral 8 denotes a cleaning means for cleaning and removing the dehydrated cake that is not separated by the scraper 7 and adhered to the filter cloth belt.

  Conventionally, the filter cloth forming the filter cloth belt 4 of the electroosmotic dehydrator is a filter cloth obtained by single weaving monofilaments made of synthetic resin, from the viewpoint of reducing the solid content concentration of waste water. Those that do not leak are used.

  When a single-woven filter cloth that does not cause leakage is used, the supplied sludge is easily repelled by the filter cloth and spreads sideways. If the input amount is increased, a problem of protruding from the filter cloth belt 4 occurs. Therefore, it is difficult to increase the amount of processing, and there is room for improvement.

  Furthermore, when the filter cloth belt 4 is formed, the single-woven filter cloth is difficult to sew together the filter cloths to form a joint, and the joint is formed by applying an adhesive or implanting metal fittings. (Patent Document 2).

  FIG. 5 is a schematic cross-sectional view showing a case where the joint portion 46 is formed by the adhesive 45. As shown in the figure, the adhesive 45 applied to the end of the filter cloth 40 protrudes from the surface of the filter cloth belt 4 and lacks smoothness.

  FIG. 6 is a schematic cross-sectional view showing a case where the fitting 47 is formed by planting the metal fitting 47 on the filter cloth 40. As shown in the figure, the loop-shaped metal fitting 47 planted on the filter cloth 40 protrudes from the surface of the filter cloth belt 4 and still lacks smoothness.

  When the filter cloth belt 4 lacking smoothness as described above is used in a belt press type electroosmotic dehydrator, the scraper 7 may be caught, so the contact of the scraper 7 with the filter cloth belt 4 is loosened. I have to deal with it. In this case, scraping of the dehydrated cake by the scraper 7 becomes insufficient, and a large amount of dehydrated cake flows out into the washing wastewater when washing by the washing means 8, and the solid content concentration of the wastewater rises remarkably. That is, as a result of trying to reduce the solid content concentration of the wastewater by reducing the leakage, more solid content is mixed into the wastewater, resulting in a situation of tipping over.

  In order to avoid an increase in the solid content concentration of the wastewater, when the filter cloth belt 4 is circulated without being sufficiently washed by the washing means 8, the efficiency of dewatering treatment of newly supplied sludge is significantly reduced. Cause problems.

  On the other hand, as a filter cloth for dehydration, a filter cloth formed by multi-weaving monofilaments made of synthetic resin is also known, but the filter cloth is easy to press the sludge into the structure, and the solid content in the sludge is the structure. In particular, in a dehydrator having a pressure dehydration process, it has not been used in order to cause clogging and shorten the life of the filter cloth.

  Thus, there has been no practical filter cloth for a conventional belt press type electroosmotic dehydrator.

JP 63-256112 A Japanese Patent No. 4108204

  The present inventor tried to select a filter cloth suitable for a belt press type electroosmotic dehydrator, and diligently studied to use a filter cloth formed by multiple weaving synthetic resin monofilaments.

  In a multi-woven filter cloth, by setting the air permeability of the filter cloth within a specific range, a large amount of treatment, a low solid content concentration of waste water, a long filter cloth life, and a smooth joint are possible. It was found that a filter cloth for a belt press type electroosmotic dehydrator could be obtained, and the present invention was completed.

  Accordingly, an object of the present invention is to provide a filter cloth for a belt press type electroosmotic dehydrator that has a large throughput, a low solid content concentration of drainage, a long filter cloth life, and a smooth joint. .

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
A rotating drum,
A press belt surrounding a part of the circumference of the rotating drum;
A DC power source for applying a voltage between the electrodes using the rotating drum as an anode and the press belt as a cathode;
A sludge supplied to one surface side, in a facing surface area between the rotating drum and the press belt, and a filter cloth belt for conveying the one surface side so as to face the rotating drum,
A filter cloth for a belt press type electroosmotic dehydrator constituting the filter cloth belt of a belt press type electroosmotic dehydrator for dewatering the sludge by an electroosmotic action by an electric field formed in the opposite surface area,
A monofilament of thermoplastic resin is woven in multiple layers, and the air permeability is 3000 to 5000 cc / cm ² · min .
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. A filter cloth for a belt press type electroosmotic dehydrator, wherein a movement path for returning the paper is suitably secured .

(Claim 2)
The filter cloth for a belt press type electroosmotic dehydrator according to claim 1, wherein the thermoplastic resin monofilament is double woven.

(Claim 3)
The filter cloth for a belt press type electroosmotic dehydrator according to claim 1 or 2, wherein the monofilament has a wire diameter of 0.35 mm to 1.00 mm.
(Claim 4)
A rotating drum,
A press belt surrounding a part of the circumference of the rotating drum;
A DC power source for applying a voltage between the electrodes using the rotating drum as an anode and the press belt as a cathode;
A sludge supplied to one surface side, in a facing surface area between the rotating drum and the press belt, and a filter cloth belt for conveying the one surface side so as to face the rotating drum,
A belt press type electroosmotic dehydrator for dewatering the sludge by an electroosmotic action by an electric field formed in the facing area;
The filter cloth belt is constituted by the filter cloth for a belt press type electroosmotic dehydrator according to any one of claims 1 to 3,
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. A belt press type electroosmotic dehydrator characterized by suitably securing a moving path for returning.
(Claim 5)
An electroosmotic dehydration method for dewatering the sludge by an electroosmotic action by an electric field formed in the opposed surface area using the belt press type electroosmotic dehydrator according to claim 4,
The filter cloth belt is constituted by the filter cloth for a belt press type electroosmotic dehydrator according to any one of claims 1 to 3,
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. An electroosmotic dehydration method characterized by suitably securing a moving path for returning.

  According to the present invention, it is possible to provide a filter cloth for a belt press type electroosmotic dehydrator that has a large throughput, a low solid content concentration of waste water, a long filter cloth life, and a smooth joint.

Schematic sectional view showing an example of filter cloth for belt press type electroosmotic dehydrator Schematic sectional view showing another example of filter cloth for belt press type electroosmotic dehydrator Schematic cross-sectional view showing an example of joint formation Schematic diagram of belt press type electroosmotic dehydrator Schematic sectional view showing the case where the joint is formed with an adhesive Schematic sectional view showing the case where the fitting is formed by planting the metal fitting on the filter cloth

  The filter cloth for a belt press type electroosmotic dehydrator according to the present invention is formed by multiple weaving monofilaments of thermoplastic resin.

  The multi-weaving is not particularly limited as long as it is a multi-weaving such as double weaving or triple weaving, but double weaving is particularly preferable.

  The schematic sectional drawing which shows the example of the filter cloth for belt press type electroosmosis dehydrators in FIG.1 and 2 was shown.

  In FIG. 1, a belt press type electroosmotic dehydrator filter cloth 40 organized in a double weave has a sludge contact surface (upper surface) 41 of 2/2 twill and a belt press contact surface (lower layer surface) 42 of Turkey. It is considered to be satin weave.

  In FIG. 2, the filter cloth 40 for the belt press type electroosmotic dehydrator organized in a double weave has a sludge contact surface 41 and a belt press contact surface 42 in a Turkish satin weave.

  By making the filter cloth into a double weave, the number of yarns arranged in the permeation direction of the filtrate increases, and the gap between the yarns is three-dimensionally formed inside the filter cloth, so the solid content capture efficiency Will improve.

Moreover, the air permeability of the filter cloth for a belt press type electroosmotic dehydrator of the present invention is 3000 to 5000 cc / cm ² · min, preferably 3500 to 4500 cc / cm ² · min. In addition, the measurement of air permeability is based on JIS L-1096.

  With the belt press type electroosmotic dehydrator filter cloth of the present invention having the above-mentioned configuration, the effect of reducing the drainage solid content concentration by suppressing the leakage of the filter cloth can be obtained, and as described in detail below. The effect of improving the throughput and prolonging the life of the filter cloth can be obtained.

  First, as described above, when no leakage occurs in the single-woven filter cloth, the supplied sludge is easily repelled by the filter cloth and spreads sideways. If the input amount is increased, a problem of protruding from the filter cloth belt 4 occurs. In order to avoid this, it was unavoidable to reduce the input amount.

  On the other hand, the filter cloth for the belt press type electroosmotic dehydrator according to the present invention has a multi-weaving, preferably a double weaving, and therefore has a sludge retention property between three-dimensionally arranged monofilaments. The sludge that is high and thus retained exhibits a friction effect against the movement of the sludge on the surface of the filter cloth spreading sideways and can be braked. As a result, the protrusion from the filter cloth belt 4 when the input amount is increased can be largely suppressed, and the processing amount is improved.

  Conventionally, when sludge is retained inside the filter cloth in this way, it has been considered that the solid content in the sludge is accumulated in the tissue, resulting in clogging and a problem of shortening the life of the filter cloth. On the other hand, the inventor focused attention on the electroosmosis phenomenon of the belt press type electroosmosis dehydrator, and diligently studied to return the sludge held inside the filter cloth in the direction opposite to the permeate side, The present invention has been completed.

  That is, since the solid content in the sludge held on the filter cloth is negatively charged, the rotating drum (anode) disposed in the direction opposite to the permeation side by voltage application in the subsequent electroosmotic dehydration treatment An attractive force is generated to move to the side.

The filter cloth for the belt press type electroosmotic dehydrator according to the present invention has a permeability of 3000 to 5000 cc / cm ² · min. It can be secured. Therefore, the solid content in the sludge is prevented from permeating through the filter cloth, and is prevented from accumulating in the tissue, thereby extending the life of the filter cloth. Since the water in the sludge held on the filter cloth is positively charged, it passes through the filter cloth with the solid content removed, and is discharged as waste water.

When the air permeability is less than 3000 cc / cm ² · min, the gap inside the filter cloth is narrowed, so that the solid content movement path according to the attractive force cannot be secured, and the solid content in the sludge is accumulated in the tissue. There is a problem of clogging and shortening the life of the filter cloth. On the other hand, when the air permeability exceeds 5000 cc / cm ² · min, the leakage increases and the solid content concentration of the waste water increases.

  As described above in detail, according to the filter cloth for the belt press type electroosmotic dehydrator of the present invention, it is possible to simultaneously reduce the drainage solid content concentration and improve the throughput, and further to prolong the life of the filter cloth. An effect is obtained.

  Further, with the filter cloth for a belt press type electroosmotic dehydrator according to the present invention, it is easy to form a joint portion by sewing or the like without using an adhesive at the end portion.

  That is, since the filter cloth for the belt press type electroosmotic dehydrator of the present invention is multi-woven, it is easy to arrange the folded ends at both ends in the length direction, and the joints can be obtained by stitching the folded ends together. The part can be formed.

  If stitching is used, the joint portion can be easily flattened, and when the scraper is brought into contact, the dewatered cake can be scraped off smoothly without being caught.

  For example, as shown in FIG. 3, a joint loop 43 made of a longitudinal thread can be formed at the folded end of the filter cloth 40, and the joint loops 43 can be sewn together by a core wire 44.

  In order to impart mechanical strength to such a joint, the wire diameter of the monofilament forming the filter cloth is preferably 0.35 mm to 1.00 mm, and preferably 0.4 to 0.8 mm. It is more preferable. The monofilament is not limited to a circular cross section, and may be an elliptical cross section, a rectangular cross section, or the like, and the wire diameter when converted to a circle is preferably within the above range. Further, the warp yarn and the weft yarn do not necessarily have the same diameter, and can have different wire diameters within the above range.

  In addition, in the electroosmotic dehydrator, when using a joint using an adhesive as shown in Patent Document 2, the water permeability of the filter cloth is impaired in the adhesive application part, and the dehydration efficiency is reduced. At the time of voltage application, the voltage rises due to the insulating properties of the adhesive, which may cause an abnormal temperature rise or ignition, which is not preferable.

  A filter fabric for a belt press type electroosmotic dehydrator is required to have high heat resistance, electrochemical stability, insulation, and mechanical strength that can withstand the heat generated by an applied voltage. Thus, these conditions can be preferably satisfied.

  Preferred examples of the thermoplastic resin include polyolefin resins such as polyester and polypropylene, and polyester is particularly preferable.

  Moreover, since it is excellent in pH stability if it is a thermoplastic resin, it can be used suitably also when the to-be-dehydrated material is alkaline or acidic. In particular, by having alkali resistance, it can be suitably used for dehydration of human waste and sewage sludge.

  Although it does not specifically limit as a processing target of the electroosmosis dehydration process by the belt press type electroosmosis dehydrator provided with the filter cloth for belt press type electroosmosis dehydrators of this invention, Sludge, dredging, livestock droppings etc. can be illustrated preferably.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

Example 1
A filter cloth having the following characteristics was attached to the electroosmotic dehydrator shown in FIG. 4 to perform electroosmotic dehydration treatment of sludge.

<Characteristics of filter cloth>
Weave: Double weave (sludge contact surface: 2/2 twill kuzu, belt press contact surface: Turkish satin weave)
Air permeability: 4000cc / cm ² · min
Thread form: Monofilament wire diameter for both warp and weft: Warp 0.30 mmH x 0.60 mmW (0.48 mm in yen), Weft 0.70 mm
Thickness: 1.78mm
Mass: 1400 g / m ²
Density: Vertical 53 / inch, Horizontal 17 × 2 / inch Strength: Vertical 500daN / 3cm, Horizontal 700daN / 3cm
Operating temperature: Maximum 150 ° C, Regular 120 ° C
Material: Polyester joint: Suture (no adhesive)

<Evaluation method>
The following items were evaluated and the results are shown in Table 1.
1. Leakage: A low solid content concentration in the dehydrated filtrate is indicated by ◯, a practically no problem is indicated by Δ, and a high solid content is indicated by ×.
2. Peelability: ○ when the amount of sludge remaining inside the filter cloth is small, Δ when there is no problem in practical use, and × when there is much sludge.
3. Strength: With respect to the breaking strength when the filter cloth was pulled in the length direction, “◯” indicates that the strength is excellent, “Δ” indicates that there is no practical problem, and “×” indicates that the filter fabric is inferior.
4). Amount of treatment: The maximum treatment amount when the sludge supplied on the filter cloth was treated so as not to protrude from the filter cloth was indicated as “◯” for the large amount, “Δ” for the practically no problem, and “×” for the small amount.
5. Scraper stability: When the scraper abuts on the joint part, the case where no catching occurs is indicated by ◯, the case where there is no practical problem is indicated by Δ, and the case where the scraper is generated is indicated by ×.

(Comparative Example 1)
The same test as in Example 1 was performed except that a filter cloth having the following characteristics was used, and the evaluation results are shown in Table 1.

<Characteristics of filter cloth>
Origata: Single weave (Twill weave)
Air permeability: 3600cc / cm ² · min
Thread type: Monofilament wire diameter for both warp and weft: Warp 0.25 mm, Weft 0.30 mm
Thickness: 0.73mm
Mass: Unmeasured Density: Vertical 112 / inch, Horizontal 49 / inch Strength: Vertical 1500 daN / 3cm, Horizontal Unmeasured Operating Temperature: Maximum 120 ° C, Regular 100 ° C
Material: Polyester joint: Adhesive used

1: Rotating drum 2: Press belt 3a-3e: Guide roll 4: Filter cloth belt 40: Filter cloth 5: DC power supply 6: Drainage receiving part 7: Scraper 8: Cleaning means

Claims (5)

A rotating drum,
A press belt surrounding a part of the circumference of the rotating drum;
A DC power source for applying a voltage between the electrodes using the rotating drum as an anode and the press belt as a cathode;
A sludge supplied to one surface side, in a facing surface area between the rotating drum and the press belt, and a filter cloth belt for conveying the one surface side so as to face the rotating drum,
A filter cloth for a belt press type electroosmotic dehydrator constituting the filter cloth belt of a belt press type electroosmotic dehydrator for dewatering the sludge by an electroosmotic action by an electric field formed in the opposite surface area,
A monofilament of thermoplastic resin is woven in multiple layers, and the air permeability is 3000 to 5000 cc / cm ² · min .
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. A filter cloth for a belt press type electroosmotic dehydrator, wherein a movement path for returning the paper is suitably secured .   The filter cloth for a belt press type electroosmotic dehydrator according to claim 1, wherein the thermoplastic resin monofilament is double woven.   The filter cloth for a belt press type electroosmotic dehydrator according to claim 1 or 2, wherein the monofilament has a wire diameter of 0.35 mm to 1.00 mm. A rotating drum,
A press belt surrounding a part of the circumference of the rotating drum;
A DC power source for applying a voltage between the electrodes using the rotating drum as an anode and the press belt as a cathode;
A sludge supplied to one surface side, in a facing surface area between the rotating drum and the press belt, and a filter cloth belt for conveying the one surface side so as to face the rotating drum,
  A belt press type electroosmotic dehydrator for dewatering the sludge by an electroosmotic action by an electric field formed in the facing area;
  The filter cloth belt is constituted by the filter cloth for a belt press type electroosmotic dehydrator according to any one of claims 1 to 3,
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. A belt press type electroosmotic dehydrator characterized by suitably securing a moving path for returning. An electroosmotic dehydration method for dewatering the sludge by an electroosmotic action by an electric field formed in the opposed surface area using the belt press type electroosmotic dehydrator according to claim 4,
The filter cloth belt is constituted by the filter cloth for a belt press type electroosmotic dehydrator according to any one of claims 1 to 3,
When supplying the sludge, the retention of the sludge inside the filter cloth is enhanced,
At the time of subsequent dehydration, the water in the sludge held inside the filter cloth is discharged through the coating, and the solid content in the sludge held inside the filter cloth is discharged to the rotating drum side. An electroosmotic dehydration method characterized by suitably securing a moving path for returning.

Images