JPH09215988A - Biological membrane filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological membrane filter which does not require to ensure washing water and incidental equipment caused by washing operation by omitting a washing process. SOLUTION: In an ascending flow biological membrane filter apparatus having a packet bad of a floated filter material 10 is passing raw water through the packed bad as ascending flow, a draft tube 9 is arranged in the packed bed and a jet pipe 8 is provided in the draft tube 9 and water streams or air accompanied by water streams is downwardly introduced into the draft tube 9 to continuously move the floatable filter material 10 from the upper part of a tank to the lower part thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upflow biofilm filter for sewage, human waste and industrial wastewater containing BOD, ammonia nitrogen and organic nitrogen.

[0002]

2. Description of the Related Art Recently, an upflow biofilm filtration method using a levitation filter medium having a diameter of 3 to 10 mm and floating in water has been actively developed. FIG. 5 is a schematic view showing an example of the biofilm filtration device. The biofilm filtration device is provided with a filter medium filling section 6, and a water collecting plate 7 which also functions as a filter medium outflow prevention is provided above the filter medium filling section 6. Float filter medium is filled in the filter medium filling section 6 and raw water 1
Through the upflow, BOD in the wastewater, ammonia nitrogen,
Organic nitrogen removal can be performed. This filtration method
BOD oxidizing bacteria, nitrifying bacteria, and denitrifying bacteria can be maintained at a high concentration in the filter bed, which is a technology that enables high-speed processing. In FIG. 5, reference numeral 2 is treated water, reference numeral 3 is wash water outlet, reference numeral 4 is wash water supply pipe, and reference numeral 5 is air pipe.

[0003]

In the above method, when water is continuously supplied, the accumulated SS (suspended matter) and BO
Periodic washing was necessary because the filtration resistance increased due to the enlargement of the biofilm due to the decomposition of D or the growth of bacterial cells accompanying nitrogen treatment. For this reason, it was necessary to secure cleaning water for backwashing, air for air washing, and additional equipment necessary for backwashing.

The present invention has been made in view of the above circumstances, and it is not necessary to secure the washing water by omitting the washing step, and it is possible to omit the auxiliary equipment resulting from the washing operation. The purpose is to provide.

[0005]

In order to achieve the above-mentioned object, the present invention provides an upflow biofilm filtration device in which a packed bed is filled with a buoyant filter medium and raw water is passed in an upward flow. A draft tube is installed in the packed bed, an ejection pipe is provided in the draft tube, and a floating water filter or the air entrained in the water flow is introduced downward into the draft tube, whereby the flotation filter medium is placed above the tank. It is characterized by continuously moving from the bottom to the bottom.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the biofilm filtration device according to the present invention will be described below with reference to FIGS. FIG. 1 is a conceptual diagram of the biofilm filtration device of the present invention. The biofilm filtration device includes a filter medium filling section 6, and a water collecting plate 7 for preventing the filter medium outflow is provided above the filter medium filling section 6. A draft tube 9 is installed at the center of the packed bed.
An ejection pipe 8 for ejecting a water flow or air entrained in the water flow downward is provided therein. The floating filter medium 10 is entrained in the downward water flow formed in the draft tube 9, and the floating filter medium at the upper part of the tank moves through the draft tube 9 to the lower part of the tank. The floating filter medium that has moved to the outside of the draft tube at the bottom of the tank moves to the top of the tank again. In this way, the floating filter medium 10
, The SS trapped between the filter media and the enlarged biofilm are peeled off, and are discharged out of the system together with the treated water. The SS discharged out of the system together with the treated water is removed by various physicochemical treatment methods such as gravity precipitation, coagulation sedimentation, and floating filtration depending on the quality of the discharged water.

When only the water flow is discharged from the jet pipe 8 in the draft tube 9, the air necessary for the oxidation of BOD and the nitrification of nitrogen is supplied, so that the outside of the draft tube is aerated from the bottom of the tank. On the other hand, in the case of water flow and entrained air, the outside of the draft tube is not aerated from the bottom of the tank. However,
When the BOD load and the ammonia load are high and a large amount of air is required, it is preferable to use the former method. As a method of entraining air in the water flow, an ejector or the like may be used instead of connecting the air pipe 5 to the discharge side of the pump 16 shown in FIG. The position of the ejection pipe 8 in the draft tube 9 varies depending on the draft tube length and the pipe diameter. Further, the position of the ejection pipe is appropriately determined according to the moving speed of the filter medium. Further, assuming that the diameter of the ejection pipe is d and the diameter of the draft tube is D, a d / D ratio of both is usually 0.4 to 0.6. However, when the gas injection amount is small, the d / D ratio is increased. can do. The moving speed of the filter medium changes depending on the apparent specific gravity of the filter medium, and the moving speed in the draft tube increases as the apparent specific gravity increases. Therefore, it is necessary to adjust the liquid amount and the air amount according to the apparent specific gravity of the filter medium. In FIG. 1, reference numeral 17 is a blower.

Next, an example in which the present method is applied to nitrogen treatment will be described with reference to FIG. In the biofilm filtration device shown in FIG. 2, the denitrification tank 11 for passing raw water in an upward flow is arranged firstly,
Subsequently, the nitrification tank 12 is arranged, and a part of the nitrification solution is returned to the denitrification tank 1 to treat BOD and nitrogen. The denitrification tank 1 and the nitrification tank 2 are each filled with a buoyant granular filter medium, and a water collecting plate that also functions as a filter medium outflow prevention is provided at the upper part of the tank. Then, the raw water is passed upward, the nitrification tank 12 oxidizes the ammoniacal nitrogen in the raw water into nitrate nitrogen by the action of nitrifying bacteria, and the denitrification tank 11 denitrifies the nitrate nitrogen in the nitrification solution. By the action of, the reduction treatment to nitrogen gas is performed while utilizing the BOD component in the raw water.

FIG. 3 is a diagram showing an example of a biofilm filtration device for removing nitrogen in one tank. The biofilm filtration device shown in FIG. 3 includes an anaerobic part 11 'and an aerobic part 12', and nitrifies ammoniacal nitrogen in the aerobic part 12 ', and a part of treated water containing nitrate nitrogen produced by nitrification. In the anaerobic section 11 ', the nitrate nitrogen in the circulating water is removed by using the BOD in the raw water. Both of these series of nitrification tanks 12 (Fig. 2) or aerobic section 12 '(Fig. 3)
The draft tube 9 is provided on the above, and the floating filter medium is continuously moved as shown in FIG.
S and the enlarged biofilm are peeled off and discharged out of the system together with the treated water. 2 and 3, reference numeral 13 indicates a nitrification tank circulating liquid, and reference numeral 5 indicates an air pipe.

FIG. 4 is a diagram showing an application example of the present method when the apparatus becomes large-scale. A partition 14 is provided between the tanks, a draft tube 9 is provided for each tank, and a jet tube 8 for jetting a water flow or air entrained in the water flow downward is provided in the draft tube 9. As a result, by continuously moving the floating filter medium as shown in FIG. 1, the SS trapped between the filter medium and the enlarged biofilm are peeled off and discharged together with the treated water to the outside of the system.

[0011]

As described above, according to the present invention,
In an upflow biofilm filtration device in which a packed bed is filled with a buoyant filter medium and raw water is passed through in an upward flow, a draft tube is installed in the packed bed, and an ejection pipe is installed in the draft tube. By providing a water flow or air entrained in the water flow downward and continuously moving the levitation filter medium from the upper part to the lower part of the tank, the SS trapped between the filter media and the enlarged biofilm are separated and treated. It is discharged out of the system together with water. Therefore, it is possible to omit the washing step that was carried out in the upflow biofilm filtration treatment using the conventional flotation filter material, and also to secure the wash water, and to eliminate the incidental equipment due to the washing operation such as the equipment for air washing, Enables continuous wastewater treatment.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a biofilm filtration device according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the biofilm filtration device according to the present invention.

FIG. 3 is a schematic view showing still another embodiment of the biofilm filtration device according to the present invention.

FIG. 4 is a schematic view showing still another embodiment of the biofilm filtration device according to the present invention.

FIG. 5 is a schematic view showing a conventional biofilm filtration device.

[Explanation of symbols]

 1 Raw water 2 Treated water 3 Wash water outlet 4 Wash water supply pipe 5 Air pipe 6 Filter medium filling part 7 Water collecting plate 8 Jet pipe 9 Draft tube 10 Floating filter medium 11 Denitrification tank 11 'Anaerobic part 12 Nitrification tank 12' Aerobic part 13 Nitrification tank circulating liquid 14 Partition wall

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuko Nanamori 11-11 Haneda Asahi-cho, Ota-ku, Tokyo Inside EBARA CORPORATION

Claims (1)

[Claims] 1. An upflow biofilm filtration device in which a packed bed is filled with a buoyant filter medium and raw water is passed through in an upward flow, and a draft tube is installed in the packed bed to provide a draft tube. Upflow biofilm filtration characterized by continuously moving the levitation filter medium from the upper part of the tank to the lower part by installing a jetting pipe in the tank and introducing water flow or air entrained in the water flow downward into the draft tube. apparatus.