JPH04305208A - Liquid filtration method - Google Patents

Abstract

PURPOSE:To improve filtration efficiency and to simultaneously ensure its action by rapidly discharging residual liquid at the time of clogging of a filter medium. CONSTITUTION:Liquid to be treated falls from above a filter medium 8 in a pressure room to filter it. When the filter medium is clogged, the liquid stops falling. Before the filter medium is replaced, the pressure room is opened to the atmosphere to forcibly discharge residual liquid remained in the pressure room. After that, the clogged filter medium part is moved to provide a new filter medium part to the filter face, and the pressure room is again sealed to start the filtration operation. Thereby a throughput per unit time can be increased with less waiting time for drain because of forced discharge of residual water on clogging.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid filtration device, and more particularly to a filtration method in which a liquid is intermittently filtered while a filter medium is intermittently supplied onto the filtration surface of the filtration device.

0002

[Prior Art] In order to effectively and efficiently filter solids in a liquid, devices that filter the liquid while supplying new filter media are used in various industrial fields. In the field of filtration of lubricants containing grinding debris, there have been proposed automatic filter paper exchange type pressurized filters that can automatically exchange filter media, and a continuous filtration method and apparatus disclosed in Japanese Unexamined Patent Publication No. 77507/1983.

0003

Problem to be Solved by the Invention However, the above-mentioned automatic filter paper exchange type pressure filter and Japanese Patent Application Laid-Open No. 63-775
According to Publication No. 07, the device works effectively when filtering hard solids such as grinding waste, but the device contains slimy microorganisms and flocs after being subjected to biological treatment or polymer flocculation treatment. In such cases, a slimy substance may adhere to the surface of the filter medium, clogging the filter medium. When the above situation occurs,
The residual water and pressure in the pressure chamber above the filtration surface do not escape even if the pressure below the filtration surface is reduced, or it takes a long time for them to escape. Also, if you raise the filter surface and open it without draining the residual water in the pressure chamber above the filter surface, the pressurized residual water will scatter and the filter material that has accumulated on the surface of the filter medium will be washed away with the flow. It was inappropriate. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a filtration device that can perform filtration processing effectively and efficiently, eliminate outflow of processing liquid when supplying filter media, and shorten the time required to replace the filter media with a new one. That is.

0004

[Means for Solving the Problems] In order to achieve the above-mentioned object, the liquid filtration system according to the present invention filters the processing liquid by flowing it down from above the filter medium in the pressure chamber. When the filter becomes clogged, the flow of the processing liquid is stopped, and before the clogged filter medium is replaced, the remaining liquid in the upper pressure chamber is forcibly discharged, and the pressure chamber is opened. The feature is that the filter medium is moved relative to the filtration surface so that the clogged part becomes a new filter medium part, and the pressure chamber is sealed again to allow the processing liquid to flow down.

[0005]

[Operation] In the fluid separation method according to the present invention, a filter medium wound into a roll is supplied to the filtration surface of a pressure chamber by a supply roll, and the processing liquid is caused to flow down from above the filter medium in the pressure chamber to be filtered. , when the filter medium becomes clogged, the clogging is detected, and based on this detection, the flow of the processing liquid is stopped, and the processing liquid remains in the upper pressure chamber before the clogged filter medium is replaced. Drain the processing liquid and open the pressure chamber to the atmosphere.
operating the supply roll and the take-out roll to feed out the wound filter medium and move the filter medium relative to the filtering surface so that the clogged filter medium section becomes a new filter medium section;
The pressure chamber is sealed again and the process liquid is repeatedly supplied from the top of the pressure chamber.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained based on an apparatus shown in the drawings. In FIG. 1, reference numeral 1 denotes a raw water tank, into which a treatment liquid 3 flows through a treatment liquid inlet 2. As shown in FIG. Reference numeral 4 denotes a raw water pump, and the raw water pump 4 supplies the processing liquid 3 in the raw water tank 1 to the upper pressure chamber 13 via the processing liquid supply pipe 31 according to instructions from the controller 7 . Reference numeral 6 denotes a flow meter installed in the processing liquid supply pipe 31 that connects the raw water tank 1 and the upper pressure chamber 13, and 5 denotes a liquid level detector for detecting the liquid level of the raw water tank 1. It is.

Reference numeral 8 denotes a filter medium wound into a roll, and the filter medium 8 is supplied into the pressure chamber via a filter medium supply roll 10 and a guide roll 11, and the filter medium that becomes clogged during filtration in the pressure chamber is removed. The filter medium 8 is moved outside from the pressure chamber by the filter medium take-out roll 12 and collected in the filter medium recovery tank 23, and the remaining amount of the filter medium 8 is detected by the remaining amount detector 9. The pressure chamber described above is composed of an upper pressure chamber 13 and a lower pressure chamber 14. The upper pressure chamber 13 is formed of a casing with many small holes in the bottom surface, and the lower pressure chamber 14 has many small holes in the top surface. It is formed of a casing-like body with holes, and a filter medium 8 is disposed between both pressure chambers 13 and 14.

Reference numeral 15 denotes a residual water tank provided at the lower part of the pressure chamber, and residual water in the upper pressure chamber 13 caused by clogging of the filter medium 8 is discharged by a solenoid valve 20 and flows into the residual water tank 15 through piping. 33 to flow back into the raw water tank 1. 1
Reference numeral 7 denotes an air valve disposed in a pipe 34 communicating with the above-mentioned upper pressure chamber 13, and is opened when the filter medium 8 becomes clogged to open the upper pressure chamber 13 to the atmosphere. Also,
18 and 19 are pressure switches and pressure gauges that detect the pressure in the upper pressure chamber 13. When the pressure switch 18 reaches a preset pressure, it sends a signal to the controller 7. Reference numeral 21 denotes a hydraulic cylinder operated by a hydraulic pump 22, and the hydraulic cylinder 21 lowers the above-mentioned upper pressure chamber 13 to press the filter medium 8 onto the filter surface. Reference numeral 16 denotes a proximity switch that detects the crimping of the filter medium 8 described above, and a signal detected by the switch 16 is transmitted to the controller 7.

The apparatus used in this embodiment is constructed as described above, and when the controller 7 is turned on, automatic operation is started and the steps proceed in the following order. (1) The hydraulic cylinder 21 is operated by the hydraulic pump 22 to lower the upper pressure chamber 13 above the filtration surface and press the filter medium 8 flowing into the pressure chamber onto the filtration surface. This operation is detected by the proximity switch 16 and the signal is sent to the controller 7.
The raw water pump 4 is activated. (2) With the raw water pump 4, the treated water 3 in the raw water tank 1 passes through the pipe 31 and enters the upper pressure chamber 13, flows down the filtration surface from above to below, and the filtered liquid flows from the lower pressure chamber 14 to the required amount. supplied to the location. During the above-described filtration, the solid matter in the treated liquid that has been separated and removed is deposited on the surface of the filter medium 8.
The pressure generated by this clogging is detected by a pressure gauge 19 and a pressure switch 18, and when the pressure switch 18 reaches a set pressure, it sends a signal to the controller 7.

(3) As mentioned above, when a signal indicating that the filter medium 8 is clogged is sent to the controller 7,
The controller 7 stops the raw water pump 4 and opens the solenoid valve 20. At this time, the air valve 17 simultaneously opens to open the upper pressure chamber 13 to the atmosphere. By opening the electromagnetic valve 20 described above, the processing liquid remaining in the upper pressure chamber 13 is forcibly discharged to the residual water receiving tank 15, and the recovered residual water is returned to the raw water tank 1 through the piping 33. In addition, if a pump or the like is attached to the tip of the solenoid valve 20 described above, the treated water can be discharged more efficiently and quickly. (4) After the processing liquid in the upper pressure chamber 13 is discharged, the hydraulic cylinder 21 is operated to move the upper pressure chamber 13 upward, the pressure contact between the filter medium 8 and the filter surface is released, and then the solids are removed. The filter medium supply roll 10 and the filter medium take-out roll 12 are operated to take up the filter medium part which has accumulated and become clogged, and moves a new filter medium part to the filter surface. The length of the filter medium to be wound may be determined in accordance with the length direction of the filter surface. After the above steps are completed, the upper pressure chamber 13 is sealed, and the above steps (1) to (4) are performed as one cycle to perform intermittent filtration.

According to this embodiment, when the processing liquid 3 is caused to flow down from above the filter medium 8 of the pressure chamber and the processing liquid 3 is filtered, when the filter medium 8 is clogged, the upper pressure due to the clogging is reduced. The pressure in the chamber 13 is detected, and upon this detection, the supply of the processing liquid 3 is stopped, and the processing liquid remaining in the upper pressure chamber is forcibly discharged before replacing the clogged filter medium, and at the same time, the upper pressure chamber is opened to the atmosphere. Since the upper pressure chamber is opened to Since the residual processing liquid is forcibly discharged, the time required until a new filter medium is supplied can be shortened.

In the present invention, the solenoid valve 20 used as a drain valve for discharging the processing liquid 3 remaining in the upper pressure chamber 13 is not limited in any way as long as it opens and closes automatically. Ball valves and butterfly type valves, which have a large opening area within the valve, are preferable because they allow for faster discharge speed. Further, the water draining pump attached to the tip of the electromagnetic valve 20 described above is not limited in any way, but a self-priming type is preferable because there will be no trouble due to air being mixed in. In the present invention, the upper and lower pressure chambers 13,
14 and the filtration surface are preferably sloped, and the angle of slope is not particularly limited, but by forming the slope, the purpose is to reduce the amount of residual water in the upper pressure chamber 13, and it is minimized. It is preferable to install it as follows.

The filter medium used in the present invention may be a knitted fabric, a woven fabric, or a non-woven fabric, but the filter medium may be a knitted fabric, a woven fabric, or a non-woven fabric, but the filter medium may have a small pore size and a high overall porosity can be obtained, for example, a 3-dimensional filter medium made of fibers.
A nonwoven fabric type having dimensional entanglement and a high entanglement density is preferable because it has good removal performance and a high filtration rate. The method of three-dimensionally entangling the fibers constituting the above-mentioned nonwoven fabric is not limited in any way, and includes columnar flow entanglement in which high-speed fluid collides with the fibrous sheet, entanglement by needle punch method, and other known methods. It can be achieved using technology.

[0014] The type of fibers constituting the fibrous sheet used in the present invention is not limited in any way, but for example,
Polyester copolymer fibers such as polyethylene terephthalate, polyethylene terephthalate adipate, polyethylene terephthalate isophthalate, polyethylene phthalate sebacate, polyethylene terephthalate dodecanedioate, polybutylene terephthalate, polyhexamethylene adipamide, polyhexane methylene hexamide, polycabramide, polyoctamide,
Polyamide fibers such as polynonamide, polydecamide, polytetraamide, polyamide/imide fibers, aromatic polyamide fibers, polyester ether fibers such as polyparaoxybenzoate, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polytetrafluoroethylene, etc. Examples include halogen-containing polymer fibers, polyolefin fibers such as polypropylene and polyethylene, various acrylic fibers and polyvinyl alcohol fibers, polyphenylene sulfite fibers, regenerated cellulose, acetate, natural fibers such as cotton, hemp, silk, and wool. . These fibers may be used alone or in combination. The fibrous sheet used in the present invention has a tensile strength when dry and wet in the direction of movement on the filtration device, and a tensile strength in a direction perpendicular to the direction of movement, such that it does not stretch when the filter medium is wound up. It is desirable to be present. Furthermore, the method of increasing the strength of the fibrous sheet is not limited in any way, and there is no problem as long as the fibrous sheet itself has the above-mentioned tensile strength, but if it is low, resin processing, heat fusion, etc. Other known techniques, such as a method of mixing fibers and increasing the strength by heat setting, may be employed.

[0015]

[Specific Examples] Next, the present invention will be described in more detail using specific examples. Specific Examples (1), (2) Comparative Example (1) The filtration device shown in Figure 1 was installed in the wastewater treatment equipment of the linen supply factory shown in Figure 2 under the conditions shown in Specific Examples (1) and (2). did. In FIG. 2, waste water from a washing machine 24 flows into a PH adjuster 25, and after being treated with activated sludge in an activated sludge treatment tank 26 and a pressurized flotation tank 27, the pressurized floated discharge is filtered by a filtration device 28. be.

Filtration device 2 in the wastewater treatment facility described above
The drainage time and filtration performance of the waste water remaining in the upper pressure chamber when the filter medium of No. 8 became clogged and the pressure drop increased were compared. Here, the filtration performance was measured and compared by the amount of suspended solids. The quantitative method was performed in accordance with JIS K0102. on the other hand,
The filter media used were 1 denier (10 μ) polyethylene terephthalate fibers cut into 10 mm pieces and 0.1
1: Denier nylon fiber cut into 8mm pieces:
Step 1 was dispersed and mixed in the same water to make a slurry with a concentration of 1%, and this slurry was made into paper using an inclined mesh paper-making machine conveyed through a 100-mesh wire mesh, with a basis weight of 100 g/m2.
I got a sheet of Next, on both sides of this sheet, the orifice diameter is 0.2 mm, and the widthwise arrangement pitch is 5.0 mm.
A columnar flow is injected from the orifice row at a pressure of 30k.
3 rows at g/cm2, then 1 at a pressure of 35kg/cm2
The treatment was carried out in 8 rows and then in 12 rows at a pressure of 10 kg/cm2, and then dried to obtain a nonwoven fabric. At this time, the tensile strength of the nonwoven fabric was 8/6.5 kg/inch in length/width. The liquid to be separated is wastewater that has been subjected to pressure flotation treatment after activated sludge treatment as described above, and most of the suspended solids in the wastewater are dead microorganisms, and the amount of suspended solids is 100%.
mg/L, and its particle size distribution was 1-50μ.

Concrete Example (1) An electric ball valve is provided in the upper pressure chamber, and the water in the upper pressure chamber is drained by its own weight. (2) A pump is attached to the upper pressure chamber to forcibly drain the upper pressure chamber. Comparative Example (1) There is no water drain port in the upper pressure chamber, and the pressure in the lower pressure chamber is reduced to drain water. Table 1 shows the measurement results of the amount of suspended solids in the waste water and the state of water drainage in the upper pressure chamber when filtered with the apparatus shown in each of the above examples. The amount of suspended solids was measured during filtration and immediately after replacing the filter cloth. Comparative example (1) in Table 1 requires a lot of time for the drainage in the upper pressure chamber to drain, and it is clear that the efficiency is poor, and the amount of suspended solids in the liquid to be separated is The high value immediately after replacing the filter cloth is due to water that overflowed into the separated water collection port when the pressure chamber was opened, and when using the present invention, the amount of suspended solids is stably removed. In addition, the water draining from the upper pressure chamber is good, and the waiting time for draining water is short, so the throughput per unit time is tripled compared to the conventional method. It can be seen that the efficiency is further improved by using a pump.

[0018]

[Table 1] The filtration flow rate of wastewater in the filtration device 28 is 10t/
Hr, the amount of suspended solids in wastewater before filtration is 100-150
mg/L, and the filtration time until the filter medium becomes clogged is 20 minutes/1 cycle.

Specific example (3), comparative example (2), (3) FIG.
The filtration device shown in FIG. 3 was installed in the wastewater treatment equipment of a linen supply factory shown in FIG. 3 under the conditions shown in Specific Example (3). In FIG. 3, waste water from a washing machine 24 is sent to a PH adjuster 25, treated with activated sludge in an activated sludge tank 26, and then filtered into a filtration device 28. As described above, the liquid to be separated at this time was wastewater after activated sludge treatment, and most of the suspended solids in the wastewater were dead microorganisms, and the amount of suspended solids was 500 mg/L.

[0020] The removal time and filtration performance of the processing liquid remaining in the upper pressure chamber when the filter medium of the filtration device 28 was clogged and the pressure drop increased were compared. Here, the filtration performance was determined by quantifying the amount of suspended solids and compared. The quantitative method is JIS
It was carried out in accordance with K0102. On the other hand, the filter medium used for filtration was created by the procedure described below. That is, a slurry liquid having a concentration of 1% was prepared by mixing short fibers of 5 denier polyester fiber with a fiber length of 10 mm and short fibers of 1 denier fiber with a fiber length of 5 mm in a weight ratio of 1:1. Using this slurry liquid, paper was made in the same manner as in Example 1 to obtain a paper sheet having a basis weight of 200 g/m2. This paper sheet was treated with a columnar water solution in exactly the same manner as in Example 1 to obtain a polyester entangled nonwoven fabric with a smooth sheet surface. This paper sheet was treated with a columnar water solution in exactly the same manner as in Example 1 to obtain a polyester entangled nonwoven fabric with a smooth sheet surface. This nonwoven fabric was further treated with phenol resin to increase its strength. At this time, the tensile strength of the nonwoven fabric was 18/14 kg/inch in length/width. As described above, the liquid to be separated is the discharge after activated sludge treatment, and the suspended solids in the wastewater are mostly dead microorganisms, and the amount of suspended solids is 500 kg/L.

Specific Example (3) An electric ball valve is provided in the upper pressure chamber, and the water in the upper pressure chamber is drained by gravity. Then, the pressure chamber was tilted 5 degrees from the horizontal direction. Comparative Example (2) There was no drain port in the upper pressure chamber, and the pressure chamber was opened without increasing the size of the residual water receiving tank and providing time for draining water. (3) A sand filtration was provided instead of the filtration device of the present invention (the sand filtration is indicated by the reference numeral 29 in FIG. 3). Table 2 shows the measurement results of the amount of suspended solids in the waste water and the state of water drainage in the upper pressure chamber when filtered with each of the above devices. The amount of suspended solids was measured during filtration and after 10 exchanges. Sand filtration was measured at the same time. Comparative example in Table 2 (
In case 2), the waiting time for the residual water in the upper pressure chamber to drain has become shorter, but the sludge that has accumulated on the filter surface after filtration is washed away by the residual water and returned to the raw water tank, resulting in less floating in the raw water. The substance cannot be removed. Work efficiency is poor because separate work is required to collect the sludge that accumulates in the raw water tank. Comparative Example (3) is a case in which the treatment was performed using conventionally used sand filtration, and it can be seen that the filtration efficiency is poorer than that of the present invention, and when the sand becomes clogged, the filtration efficiency decreases. It can be seen that suspended solids are stably removed in the method according to the present invention. Furthermore, even when compared with the specific example (1) by providing the pressure chamber with an inclination, it can be seen that the throughput per unit time is also equivalent to the comparative example (2) in which no waiting time is provided.

[0022]

[Table 2] The filtration flow rate of wastewater is 10t/Hr, the amount of suspended solids in the wastewater before filtration is 800mg/L, the filtration time until the filter material becomes clogged is 15 minutes/cycle, and the sand filtration is 10 hours. After 150 minutes, the separated water was collected.

[0023]

Effects of the Invention In the liquid filtration method according to the present invention, a filter material wound into a roll is supplied to the filtration surface of a pressure chamber by a supply roll, and the treated liquid is caused to flow down from above the filter material in the pressure chamber to be filtered. When the filter medium becomes clogged due to filtration, the flow of the processing liquid is stopped, and before replacing the clogged filter medium, the residual processing liquid in the upper pressure chamber is forcibly drained and the pressure chamber is closed. The pressure chamber is opened, the filter medium supply roll is driven, the filter medium is moved so that the clogged filter medium section becomes a new filter medium section, and the pressure chamber is sealed again to repeat the filtration work. In this system, the supply of processing liquid is immediately stopped when the filter medium becomes clogged, and the remaining processing liquid in the upper pressure chamber is forcibly discharged, reducing the waiting time for draining water. To,
Effective filtration work can be carried out efficiently and the throughput per unit time can be improved, and since the pressure chamber is opened, the residual water will not be scattered. The scope of application of the filtration method according to the present invention includes, for example, conventional wastewater treatment such as drainage equipment of linen supply factories and drainage equipment of car wash factories, solid-liquid separation such as filtration of machine oil in the processing process of machine parts. It can be used for everything.

[Brief explanation of drawings]

[Fig. 1] Overall explanatory diagram of an apparatus for carrying out the filtration method of the present invention.

[Figure 2] Flow sheet showing an example of applying the present invention to drainage equipment at a linen supply factory

[Figure 3] Flow sheet showing an example different from Figure 2 when the present invention is applied to drainage equipment at a linen supply factory.

[Explanation of symbols]

1 Raw water tank 4 Raw water pump 5 Liquid level detector 6 Flowmeter 7 Controller 8 Filter medium 10 Filter media supply roll 12 Filter media removal roll 13 Upper pressure chamber 14 Lower pressure chamber 15 Residual water tank 17 Air valve 18 Pressure switch 19 Pressure gauge 20 Solenoid valve 21 Hydraulic cylinder

Claims (2)

[Claims] 1. The processing liquid is filtered by flowing down from above a filter medium in a pressure chamber, and when the filter medium becomes clogged, the flow of the processing liquid is stopped, and the clogged filter medium is removed. Before replacement, the residual liquid in the upper pressure chamber is forcibly discharged, the pressure chamber is opened, and the filter medium is moved relative to the filter surface so that the clogged part of the filter medium becomes a new filter medium part,
A liquid filtration method characterized by sealing the pressure chamber again and allowing the processing liquid to flow down. 2. The liquid supply system according to claim 1, wherein the upper pressure chamber and the filtration surface are inclined.