JPH0629683U - Solid-liquid separation device - Google Patents

Abstract

(57) [Summary] [Purpose] A solid-liquid separation device that does not require a backwash drainage receiving tank, which was indispensable in conventional equipment, and requires a small installation area, and that has a uniform load of suspended solids of raw water. provide. [Structure] A long fiber filtering device 6 filled with a long fiber bundle 7 is attached to a stage subsequent to the floating separation device 4. The long fiber filtration device 6
A return pipe 9 is provided for returning the backwash drainage generated during the backwash to the raw water tank 1 installed in the preceding stage of the flotation separator 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to improvement of a solid-liquid separation device for separating and removing suspended substances existing in raw water such as tap water, industrial water, river water, lake water, various process intermediate water, various recovered water, and various industrial wastewater. It is a thing.

[0002]

[Prior art]

 As a solid-liquid separation device that separates and removes suspended solids contained in raw water such as tap water, industrial water, river water, and various industrial wastewater, a structure with a sand filter attached to the latter stage of the coagulating sedimentation tank has been used in the past. Are commonly used. FIG. 2 shows an outline of such a conventional general solid-liquid separator. In the figure, 21 is a raw water tank for temporarily storing raw water to be treated, and 22 is a raw water sent from the raw water tank 21. A flocculation reaction tank for adding a flocculant such as aluminum sulfate or polyaluminum chloride to the water to coarsen the solid content in the raw water, and 23 is a suspended solid in the raw water sent from the flocculation reaction tank 22. A coagulation-sedimentation tank for separating and separating the components, and 24 is a sand filter attached to the subsequent stage of the coagulation-sedimentation tank 23 for separating the carry-over solids from the coagulation-sedimentation tank 23 by filtration. Reference numeral 25 denotes a backwash drainage storage tank for storing a large amount of backwash drainage generated when the sand filter 24 is backwashed. If the backwash drainage receiving tank 25 does not have enough space for installation, the backwash drainage should be discharged into the sludge thickening tank 26 of the suspended solids (sludge) separated in the settling tank 23. In some cases, the backwash drainage tank 25 may not be installed.

[0003]

[Problems to be solved by the device]

 As described above, the conventional solid-liquid separation device generally has a structure in which a sand filter is attached to the subsequent stage of the coagulation sedimentation tank. However, this conventional apparatus has a drawback that the proportion of the area occupied by the coagulation sedimentation tank for sedimenting and separating the suspended solids in the raw water is very large. For this reason, this flocculation sedimentation tank can be replaced with a flotation separation device that does not require much site area, and the concentration of separated solids is higher than in the case of coagulation sedimentation, and the sludge concentration tank can be deleted. However, if the flotation device is replaced, it has the following drawbacks. That is, if the sand filter filters the solid content carried over from the flotation device, a large amount of wastewater is generated during backwashing of the sand filter, and it was possible to remove the backwash drainage tank or remove it. It is necessary to install a tank such as a sludge thickening tank with a volume that can receive backwash wastewater. Also, if the backwash wastewater from the sand filter is returned to the raw water tank located in the previous stage of the flotation separator, the amount of wastewater generated during backwashing will be large, and the raw water tank must be enlarged in size. Fluctuations in the concentration of suspended solids contained in water flowing into the flotation device become significantly large, which adversely affects the flotation separation of solids in the flotation device.

Therefore, the present invention solves the problems of the conventional solid-liquid separator having a sand filter attached to the latter stage of the coagulating sedimentation tank, and does not require much installation space in place of the sedimentation tank. In addition, instead of the conventional sand filter, a long-fiber filter that is filled with a long-fiber bundle that does not generate a large amount of drainage during backwashing is used, and the backwash drainage can be returned to the front stage of the flotation separator. It is an object of the present invention to provide a solid-liquid separation device in which the solid content load of raw water does not fluctuate so much.

[0005]

[Means for Solving the Problems]

 To describe the structure of the present invention for achieving the above-mentioned purpose in detail, a long-fiber filtering device filled with a long-fiber bundle is attached after the flotation / separation device, and occurs when the long-fiber filtering device is backwashed. This is a solid-liquid separation device characterized by being provided with a return pipe for returning the backwash drainage to the raw water tank installed in the preceding stage of the flotation separation device, and according to the device of the present invention, it was conventionally indispensable. It eliminates the need for a backwash drainage tank and, in some cases, a sludge thickening tank, and can greatly reduce the site area and also make the solid content load on the flotation separator uniform.

[0006]

[Embodiment] Hereinafter, a specific configuration of the solid-liquid separation device of the present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a schematic diagram showing an example of the flow of the device of the present invention. In the figure, 1 is a raw water tank for temporarily storing raw water to be treated, and 2 is raw water sent from the raw water tank 1. A flocculation reaction tank for adding a flocculant such as minium or polyaluminum chloride to coarsen the solid content in the raw water, and 3 is the raw water containing the suspended solid content sent from the flocculation reaction tank 2. It is a pressurized water tank for injecting aerated pressurized water into.

Reference numeral 4 denotes a flotation separator, which feeds raw water from the flocculation reaction tank 2 to the flotation separator 4 midway in the raw water supply pipe 5, in which a large amount of air is dissolved under pressure by the pressurized water tank 3. Since the pressurized water is mixed with the raw water, the bubbles generated from the pressurized water in the flotation device 4 adhere to the suspended solids in the raw water, and the solids are floated and separated from the raw water. The floating suspended solids (scum) that have floated to the surface of the flotation tank in the flotation device 4 are scraped off by a not-shown scraping scraper, etc. It is dropped into a discharge groove (not shown) provided in the section, and is discharged to the outside through discharge means 13.

Reference numeral 6 denotes a long fiber filtration device attached to the latter stage of the floating separation device 4. A long fiber bundle 7 having a length of 0.4 to 3.0 m, which is an aggregate of non-twisted single fibers such as acrylic fibers, polyester fibers, and polyamide fibers, is supported in the long fiber filtering device 6 at its lower end. It is fixed to the plate 14 and is relatively densely filled in an upright state with the upper end being a free end. By passing the supernatant water flowing out from the floating separation device 4 in a downward flow, The suspended solids that are mixed and carry over are captured, and the filtered water is taken out through the discharge pipe 8 which is connected to the lower end.

In this way, according to the present invention, the flotation separation device 4 and the long fiber filtration device 6 are combined, and the backwash drainage generated when the long fiber filtration device 6 is backwashed is installed in the preceding stage of the flotation separation device 4. A return pipe 9 for returning to the raw water tank 1 is provided. In other words, when the long fiber bundle 7 filled in the long fiber filtering device 6 captures suspended solids and the pressure loss in the filtering device 6 increases, the lower part of the long fiber filtering device 6 is reduced. For example, compressed air is blown into the long fiber bundle 7 to agitate and oscillate, and then backwash water is sent in ascending flow to wash out suspended solids. In the case of a long fiber filtration device, the long fiber bundle 7 is used. Since the lower end of the filter is fixed to the support plate 13, high-velocity compressed air or backwash water can be flowed in, so that compared to the conventional sand filter, the suspended solids can be efficiently suspended. It is possible to remove the amount of water, and the amount of backwashing water discharged once can be reduced to about 1/4 as compared with the conventional sand filter. Therefore, even if the backwash drainage generated during backwashing of the long fiber filtration device 6 is returned to the raw water tank 1 or the like in the preceding stage of the flotation separation device 4 through the return pipe 9, it is necessary to enlarge the capacity of the raw water tank 1 without necessity. In addition, since the solid content load of the flotation separator is not greatly changed, it is possible to return the backwash drainage to the front stage of the flotation separator 4 without any trouble.

In addition, in the figure, 10 is a pipe that connects the raw water tank 1 and the flocculation reaction tank 2 to each other, and 11 is a part (20 to 30%) of the suspended water from which suspended solids have been removed by the flotation / separation device 4. Is a supply pipe for supplying water to the pressurized water tank 3, and reference numeral 12 is a filtered water feed pipe branched from a discharge pipe 8 communicating with the lower end of the long fiber filtration device 6. Is for sending. The filtered water is sent to a treated water tank (not shown) through the discharge pipe 8.

Next, a comparative example of the conventional solid-liquid separation device shown in FIG. 2 and the solid-liquid separation device according to the present invention shown in FIG. 1 will be described. Raw water with a solid content concentration of 50 mg / l, a flow rate of 84.2 m³In the case of solid-liquid separation with a conventional device at a water flow rate of / m / h, if the coagulation sedimentation tank water flow LV (linear velocity) is 0.6 m / h and the sand filter water flow LV is 7 m / h, the required installation area is Coagulation sedimentation tank 141m ² (13.4 mφ), sand filter is 12.3 m²(2.8 mφ x 2 units). The amount of SS (suspended solids) captured by the sand filter is 3 kgSS / m.²The backwash was carried out by passing water for 10 minutes at LV 36 m / h. The amount of backwash drainage once is 88.7m³And the solid content concentration was 416 mg / l. The water quality of the treated water was about 21 mg / l in the treated water in the coagulation-sedimentation tank, and about 3 mg / l in the solid content in the treated water after sand filtration. The sludge (separated solids) discharged from the coagulating sedimentation tank had a concentration of about 0.8%. In addition, as other auxiliary equipment, the raw water tank in Figure 2 is 200m³, Agglomeration reaction tank 2 1.3m³, Sludge thickening tank 10m³, Backwash drainage tank is 100m³Will be needed.

On the other hand, when solid-liquid separation of the same raw water as described above is performed by the device of the present invention, the water flow LV of the flotation separator is 4 m / h or more, and the water flow LV of the long fiber filtration device is 40 m / h. The required installation area is 28.3 m ² (6 mφ) for the flotation separator and 2.3 m ² (1.2 mφ × 2 units) for the long fiber filtration device. Compared to the case of the device, the installation area can be reduced significantly. The SS capture amount of the long fiber filtration device was 3.2 kg SS / m ² , and the backwash was performed by passing water through the LV 100 m / h for 5 minutes. In this case, the amount of backwash drainage per wash was 22.6 m ³ , and the solid content concentration was 320 mg / l. Even if it was returned to the raw water tank (200 m ³ ) in the previous stage of the flotation separator, it was returned to the flotation separator. The fluctuation of the solid content load against water is suppressed to a maximum of about 1.5 times that of the inflowing raw water. The quality of treated water by the equipment was the same. The concentration of separated solids was about 3.2% in most of the floating operations (scum) and about 0.9% in some of the bottom sludge. Therefore, although 1.35 m ³ of pressurized water tank will be added as other auxiliary equipment, the backwash drainage tank and sludge thickening tank will be deleted without increasing the sizes of the raw water tank and the coagulation reaction tank compared to the conventional equipment. This makes it possible to reduce the installation area drastically as a whole.

In addition, for the same treatment of raw water as described above, a sand filter is attached to the rear stage of the flotation device to return the sand filter backwash drainage to the raw water tank through the return pipe as in the case of FIG. The aim was to remove the backwash drainage receiving tank, but the size of the raw water tank was set to 200 m in order to receive the backwashing drainage. ³ From 300m³It is necessary to increase the size of the raw water tank, and even if the raw water tank is increased in size in this way, the fluctuation of the solid content load on the flotation separator is the maximum and shows a value that is more than three times the inflowing raw water. Floating separation processing could not be performed. The other operating conditions in this case were in accordance with the above operating conditions.

[0014]

[Effect of device]

 As described above, the solid-liquid separation device of the present invention is provided with a long fiber filtering device, which is filled with long fiber bundles, at the latter stage of the flotation device, and the backwash drainage generated during backwashing of the long fiber filtering device is floated. Since a return pipe for returning to the raw water tank installed in the previous stage of the separation device is installed, the backwash drainage receiving tank, which was indispensable in the past, is not required, and the flotation separation device and the long fiber filtration device itself have a large equipment area. Combined with the fact that it does not require, it is possible to significantly reduce the site area. In addition, since the amount of backwash wastewater generated during backwashing of the long fiber filter is significantly smaller than that of the conventional sand filter, even when the backwash wastewater is returned to the raw water tank, the solid content for the flotation separator is reduced. The partial load does not increase so much, and therefore the levitation separation process can be performed without any problems.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a flow of a solid-liquid separation device according to the present invention.

FIG. 2 is a schematic diagram showing an example of a flow of a conventional solid-liquid separation device.

[Explanation of symbols]

1: Raw water tank 2: Coagulation reaction tank 3: Pressurized water tank 4: Floating separation device 5: Raw water supply pipe 6: Long fiber filtration device 7: Long fiber bundle 8: Discharge pipe 9: Return pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B01D 29/62 36/00 6953-4D C02F 9/00 Z 7446-4D

Claims (1)

[Scope of utility model registration request] 1. A raw fiber in which a long fiber filtration device filled with a long fiber bundle is attached to a stage subsequent to the flotation device, and backwash drainage generated during backwashing of the long fiber filtration device is placed in a stage preceding the flotation device. A solid-liquid separation device comprising a return pipe for returning to the water tank.