JPH09215987A - Biomembrane filtrater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the amt. of air and the amt. of water during cleaning by providing an ejecting pipe for ejecting water flow or water flow and air in the horizontal direction in a filling layer to make it possible to feed a liq. in a tank into the ejecting pipe by means of a pump and connecting an air pipeline with the electing pipe. SOLUTION: A water collecting plate 8 for preventing a filter media from flowing out is provided on the top part of a filter media filling layer 7 and in addition, a cleaning water feeding pipe 11' for feeding cleaning water is arranged. On the other hand, a cleaning pipe 11 is drawn out from the bottom part of the filter media filling layer 7 and is connected with an ejecting pipe 14 arranged in the filter medium filling layer 7 through a pump 12. An air pipeline 10 is connected with the ejecting pipe 14 and water flow from the pump 12 or a mixture of the water flow and air from a blower 9 is fed by ejection from the ejecting pipe 14 in the horizontal direction into the filter media filling layer 7. It is possible thereby to decrease the amt. of air and the amt. of water during cleaning.

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, a biofilm filtration process using a floating granular filter medium has been actively developed. These biologically treat organic matter and nitrogen in the water to be treated.

FIG. 5 is a schematic view showing an example of a conventional biofilm filtration device. In the biofilm filtration device, firstly, a denitrification tank 1 for passing raw water 4 in an upward flow is arranged, then a nitrification tank 2 is arranged, a part of the nitrification liquid is returned to the denitrification tank 1, and the BOD , Like to treat nitrogen.

In FIG. 5, reference numeral 3 is a nitrification tank circulating liquid, and reference numeral 6 is treated water. 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 nitric acid tank 2 oxidizes the ammoniacal nitrogen in the raw water into nitrate nitrogen by the action of the nitrifying bacteria, and the denitrification tank 1 denitrifies the nitric acid nitrogen in the nitrification solution. Action of BOD in raw water
Reduction treatment to nitrogen gas is performed while utilizing the components.

FIG. 6 is a schematic view showing another example of a conventional biofilm filtration device, showing a biofilm filtration device for removing nitrogen in one tank. The biofilm filtration device includes an anaerobic part 1'and an aerobic part 2 ', nitrifying ammoniacal nitrogen in the aerobic part 2', and partially treating the treated water containing nitrate nitrogen generated by nitrification. In 1 ', BOD in raw water is used to remove nitrate nitrogen in circulating water.

In both the denitrification tank, the case in which the nitrification tank is separated (FIG. 5), and the case in which it is a single tank (FIG. 6),
When water is passed, the filter layer is clogged due to the accumulation of trapped SS (suspended substances) and the growth of biofilms, which usually requires washing. Generally, in the biofilm filtration process, there are many cases where a filter material heavier than water is used, and the cleaning method is an air cleaning step in which air is supplied from the lower part of the filter tank or water is supplied from the lower part of the filter tank. Washing is performed by combining a water washing step, and an air and water simultaneous washing step in which air washing and water washing are performed at the same time.
On the other hand, when applied to a filter device having a floatable filter medium,
Air is aerated from the lower part of the filter tank, and water flows downward from the upper part of the filter tank.

[0007]

Since the above-mentioned levitation filter medium floats on water, it has an advantage that the amount of air and the amount of water at the time of cleaning can be smaller than those of a filter medium that is heavier than water. When a filter medium having a large particle size, for example, a particle size of 5 mm or more is used, SS trapping is changed from surface layer filtration to volumetric filtration, the entire tank can be effectively used, a rapid increase in filtration resistance is eliminated, and the frequency of cleaning tends to be low.
However, when the combination of filter media due to the enlargement of biofilm due to the growth of bacterial bodies such as denitrifying bacteria other than SS, BOD oxidizing bacteria, nitrifying bacteria, etc. becomes remarkable, the filter media itself is lighter than water, It was necessary to use a large amount of washing water and air, contrary to the usual case, when washing the air from the bottom of the tank and washing the water from the top of the tank, as compared with a filter medium that is heavier than water.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a biofilm filtration device that can reduce the amount of air and water during washing and that is less frequently washed.

[0009]

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 jet pipe for jetting a water flow or a water flow and air in a horizontal direction in a packed bed is provided, the liquid in the tank can be supplied to the jet pipe by a pump, and an air pipe is connected to the pipe. Is.

[0010]

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 is provided with a filter medium filling section 7, and a water collecting plate 8 for preventing the filter medium outflow is provided above the filter medium filling section 7. A cleaning water supply pipe 11 'for supplying cleaning water to the filter material filling section 7 is arranged above the filling section. The cleaning pipe 11 is pulled out from the bottom of the tank,
Jet pipe 14 installed in the filling section via the pump 12
It is connected to the. The air pipe 10 is connected to the pump discharge side so that air and water can be mixed well. A blower 9 is installed in the air pipe 10. The air pipe 10 is also connected to the bottom of the filtration tank and can be used for normal air cleaning. Reference numeral 13 is a wash water outlet.

FIG. 2 is a diagram showing details of the portion A of FIG. The ejection pipe 14 shown in FIG. 2 has a structure branched in multiple directions. When the ejection pipe is branched in multiple directions as shown in Fig. 2,
Either case for the unidirectional case can be used. The branch of the ejection pipe is used properly depending on the size of the device and SS trapping property.

3 and 4 are views showing various structures of the ejection pipe. As shown in FIG. 3, a plurality of jet pipes 14 are branched in the vertical direction of the tank, and an automatic valve 15 is opened / closed to arbitrarily wash water,
Can supply cleaning water + air. Further, when the apparatus becomes large-scale, as shown in FIG. 4, a plurality of jet pipes 14 are branched in the horizontal direction of the tank, and the automatic valve 15 is opened / closed to optionally supply washing water or washing water + air. The automatic valve 15 can be opened or closed all at once or can be opened or closed sequentially by a timer-16. In addition,
As the automatic valve, a solenoid valve, a motor-operated valve, or the like can be used, and a valve that opens and closes can be driven by air pressure in addition to electricity.

The step of cleaning the floating filter medium uses water and air,
Air is supplied from the lower part of the filter tank, and water is supplied from the upper part of the filter tank.

Here, the filter medium is a biofilm swelling or inflow S
When S is trapped and it becomes difficult to loosen during cleaning, the cleaning water or the cleaning water + air is introduced from the ejection pipe 14 during the air cleaning or the air cleaning. At the time of washing with air, only the washing water is introduced from the jet pipe 14, and at the time of washing with water, the washing water + air is introduced from the jet pipe 14.

Next, a comparative example of the present invention and the conventional method will be shown. diameter
Two 500mm, 5000mm high transparent PVC experimental equipment,
It has the same arrangement as the flow shown in FIG. There are two series (the present invention and the conventional method). As the filler, a floating filter medium having a particle diameter of 5 mm was used, and 2 m were filled in each of the denitrification tank and the nitrification tank. The target wastewater is the first settling runoff of sewage. Washing was performed by the method of the present invention and the conventional method under a steady state in which nitrifying bacteria and denitrifying bacteria were sufficiently adhered to the filter media in each tank. The washing was performed when the filtration resistance became 100 to 200 cmH ₂ O or more. At this time, the floating filter medium was in a united state.

In the conventional method, when washing is carried out in a state where the filter media are not united, the amount of air at the time of washing with water and washing with empty water is 0.2 to 0.3.
m ³ / (m ² · min), the amount washed with water is about 0.8 to 1.2 m ³ / (m ² · min). However, the filter media coalesces and the filtration resistance is 100-200 cmH ₂ O.
In this case, the amount of air in the conventional method is 0.
Cleaning was required under the conditions of 5 to 0.8 m ³ / (m ² · min) and the amount of washing with water 1.5 to 2.5 m ³ / (m ² · min). On the other hand, in the present invention, the amount of air is 0.
2m ³ / (m ² · min) and the amount of washing with water needed 0.8m ³ / (m ² · min). As described above, according to the present invention, even in the case where the filter media are combined, the amount of air and the amount of water to be washed are the same as those in the usual case, and the washing can be performed. The amount of air from the jet pipe and the amount of water washed in the present invention are included in the above values.

[0017]

As described above, according to the present invention, the water flow or the water flow + from the jet pipe installed in the filter layer at the time of cleaning
By introducing air horizontally, it is possible to reduce the amount of air and water during cleaning when the filter media coalesces and the filtration resistance becomes high to less than half that of the conventional method, and at the same time the cleaning frequency can be significantly reduced compared to the conventional method. .

[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 diagram showing details of a portion A in FIG.

FIG. 3 is a diagram showing an example of an ejection pipe.

FIG. 4 is a diagram showing another example of the ejection pipe.

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

FIG. 6 is a schematic view showing another example of a conventional biofilm filtration device.

[Explanation of symbols]

 1 Denitrification tank 1'Anaerobic part 2 Nitrification tank 2'Aerobic part 3 Nitrification tank Circulating liquid 4 Raw water 5 Air pipe 6 Treated water 7 Filter medium filling part 8 Water collecting plate 9 Blower 10 Air pipe 11 Wash water pipe 11 'Wash water supply Piping 12 Pump 13 Wash water discharge port 14 Jet pipe 15 Automatic valve 16 Timer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuko Nanamori 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside EBARA CORPORATION

Claims (3)

[Claims] 1. 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, and a water flow or a water flow and air are jetted horizontally in the packed bed. An upward flow biofilm filtration device, characterized in that a jet pipe is provided, a liquid in the tank can be supplied to the jet pipe by a pump, and an air pipe is connected to the jet pipe. 2. The upflow biofilm filtration device according to claim 1, wherein a plurality of the ejection pipes are branched in multiple directions. 3. A plurality of piping lines including the ejection pipes are arranged in a horizontal direction or a vertical direction, the piping lines are connected to a circulating liquid supply pipe in the tank, and the plural ejection pipes are collectively and divided by an automatic valve. The upflow biofilm filtration device according to claim 1 or 2, wherein the circulating liquid can be supplied.