JP2007111598A - Apparatus for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for treating waste water, in which reduction of the amount of sludge to be generated and improvement of the efficiency when oxygen is dissolved are achieved simultaneously without preparing a large installation space of equipment outside a reaction tank. <P>SOLUTION: The apparatus for treating waste water is characterized in that activated sludge is used and an ultrasonic wave generating means is arranged in the reaction tank having an air diffuser. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biological treatment apparatus using activated sludge, such as sewage, industrial wastewater, and rural village wastewater.

  Biological treatment equipment called activated sludge process is used for the treatment of sewage, industrial wastewater, rural village wastewater, and the like. In this method, polluted substances contained in sewage, industrial wastewater, and rural village wastewater are decomposed by a group of microorganisms called activated sludge to obtain a clear treated water. Generally, activated sludge treatment requires oxygen supply to microorganisms, and a diffuser called diffuser, diffuser plate, diffuser cylinder, aerator, etc. is installed near the bottom of the reaction tank to make fine air bubbles. Is blowing into the reaction tank.

  In the activated sludge method, microorganisms multiply, and excess microorganisms (excess sludge) are extracted and disposed. For the purpose of reducing the amount of generated sludge and reducing sludge disposal costs. , A method of decomposing activated sludge by ozone (see Patent Document 1), a method of decomposing using high-temperature and high-heated bacteria (see Patent Document 2), a method of ultrasonically decomposing (see Patent Document 3), and crushing and decomposing sludge A method (see Patent Document 4) has been developed.

  In the method of decomposing surplus sludge with ultrasonic waves, activated sludge slurry is drawn out from a biological treatment tank for biologically treating sewage with a pump and is put into an ultrasonic treatment apparatus, where decomposition by ultrasonic waves is performed.

  On the other hand, when treating sewage with a biological treatment device, there is known a method of providing a gas-solid-liquid refinement device as a premise of an aeration tank and putting a reaction promoting gas such as sewage and air into it. (See Patent Document 5). The refined water is sequentially sent to an aeration tank and a sedimentation tank. The above-mentioned miniaturization treatment is performed by a device that repeatedly pressurizes and depressurizes by changing the diameter of the liquid feeding pipe called SAM provided outside the gas-solid-liquid micronization tank, whereby the ice is microclustered with ultrasonic waves, and Microbubbles are generated and returned to the gas-solid liquid refinement tank.

JP-A-8-132095 JP 2002-166289 A JP 2003-117579 A JP 2000-317496 A JP-A-7-51686

The above-described technology for reducing the amount of generated sludge involves sludge treatment outside the activated sludge reaction tank, and requires extra space (site) for installation of equipment outside the reaction tank. In addition, these techniques do not have a function of increasing the oxygen dissolution efficiency.
In addition, the method of providing a gas-solid-liquid micronizer as a premise of the aeration tank also requires a separate space for this device, and the problem is that this device is expensive. Further, this apparatus also requires an aeration apparatus (FIG. 4), and nothing is shown about improving the dissolution efficiency of oxygen in the aeration.
In general, in the activated sludge treatment process, about 40% of the treatment energy is consumed for dissolving oxygen, and increasing the oxygen dissolution efficiency (the amount of dissolved oxygen per unit consumption energy) is significant for the energy saving of the treatment. effective.
An object of the present invention is to simultaneously achieve the effect of reducing the amount of generated sludge and the improvement of oxygen dissolution efficiency without providing a large facility installation space outside the reaction tank.

  The present invention has been made to solve the above-mentioned problem, and in a wastewater treatment apparatus using activated sludge, wastewater treatment characterized by installing ultrasonic generating means in a reaction tank equipped with a diffuser. The waste water treatment apparatus, wherein the ultrasonic generation means has an ultrasonic vibration plate and an ultrasonic vibrator unit, and the ultrasonic vibration plate is installed in a bubble existing portion, The above-mentioned wastewater treatment apparatus, wherein a plurality of ultrasonic wave generating means are arranged in a vertical direction and / or are characterized in that the ultrasonic vibrator unit has a watertight structure and is installed in a bubble existing portion together with the ultrasonic vibration plate. The above-described wastewater treatment apparatus is provided, wherein the wastewater treatment apparatus is arranged in a plurality of stages in the horizontal direction and is installed with the horizontal center being shifted between the means adjacent in the vertical direction.

  With the configuration in which the ultrasonic generator is directly inserted into the reaction tank, the effect of reducing the amount of generated sludge and the improvement of the oxygen dissolution efficiency can be achieved simultaneously without providing a large facility installation space outside the reaction tank. Furthermore, since the waste heat of the ultrasonic generator can be efficiently released to the surrounding activated sludge liquid, it is not particularly necessary to provide cooling water (water cooling equipment) or a cooling fan (air cooling equipment). The ultrasonic generators are arranged in multiple stages in the vertical direction, and the horizontal center is shifted between the vertical devices so that the bubbles that have become coarse due to the coalescence of the bubbles are installed. It is possible to efficiently reduce the size and obtain a higher oxygen dissolution efficiency.

The reaction tank of the wastewater treatment apparatus of the present invention is also called an aeration tank, and its shape is generally box-shaped or cylindrical. The volume varies greatly depending on the amount of wastewater to be treated, but is generally about 125 to 1000 m ³ per pond. A stirrer, a baffle plate, etc. may be provided in the inside as needed.

The air diffuser normally blows out air or a mixed gas of oxygen and air, and those used in the aeration tank of the activated sludge apparatus can be used as they are. The mounting position is usually near the bottom of the reaction tank. Chikiryou is usually per area of the air diffuser, per unit time ^{10m 3 / m · hr~100m 3 /} m · about hr.

  The ultrasonic wave generating means includes an ultrasonic wave transmitter, an ultrasonic vibrator unit connected to the ultrasonic wave transmitter, and an ultrasonic vibration plate that is connected to the vibrator and vibrates in water.

The ultrasonic diaphragm has an outer diameter of about 5 to 100 cm, preferably about 10 to 50 cm, and is made of titanium or the like. The shape is horn-like, plate-like (disk-like, square-plate-like, etc.), etc. Protruding around these, drilling many holes, or forming with mesh (mesh shape) it can.
The installation position is about 10 to 200 cm above the air diffuser, preferably about 70 to 150 cm. A plurality of ultrasonic wave generating means can be provided, and about ² to 4 pieces / m ² is appropriate. In that case, it is preferable to shift the center position so that the center position is evenly distributed.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the basic configuration of the present invention. Bubbles blown from a diffuser (4) installed in a reaction tank (3) from a blower (1) through a header pipe (2). Are fine bubbles (5) immediately above the air diffuser (4), but the bubbles are united and the bubbles are coarsened (6, 7). For this reason, normally, since the bubbles move to the water surface while repeating the coalescence of the bubbles, the gas-liquid contact area decreases, and the oxygen dissolution efficiency decreases. In the present invention, the bubbles are refined again by the ultrasonic moving plate (8) (9). For this reason, a bubble contact area becomes large and oxygen dissolution efficiency increases. Since the ultrasonic transducer unit, which is the main heat generating part, is installed in water, the generated heat moves quickly to the liquid side, so that no special cooling means (water cooling, air cooling) is necessary. Moreover, since the equipment installed outside the reaction tank is basically only an ultrasonic transmitter (amplifier), the space required outside the reaction tank is very small compared to the conventional method.

  Furthermore, since the activated sludge around the ultrasonic diaphragm is decomposed and solubilized by the action of ultrasonic waves, an effect of reducing the amount of generated sludge can be obtained at the same time.

  The actual city sewage treatment was carried out using the apparatus having the basic configuration shown in FIG. For the comparative control series, an apparatus having the same configuration was used except that no ultrasonic generator was installed. The effective water depth of the reaction tank is 4 m, and the width and depth of the reaction tank are each 1 m. As a diffuser, a commercially available rubber membrane diffuser was installed at a position 50 cm from the lower part.

  In the present invention, an ultrasonic vibration plate having a diameter of 50 cm is installed at a position 1.5 m directly above the diffuser, and 20 KH ultrasonic waves are continuously output. As the raw water, the first settling basin overflow water of the municipal sewage treatment plant was used, and the treatment was performed under the condition of a residence time of 6 hours. The activated sludge treated water was solid-liquid separated in the final sedimentation basin installed at the latter stage, the activated sludge (microorganisms) was returned to the reaction tank, and the treated water was discharged. The microorganism concentration (MLSS) in the reaction tank was set to 2500 mg / L, and the microorganisms that grew too much were extracted as excess sludge. The amount of air blown was controlled so that the dissolved oxygen concentration inside the reaction tank was 2 mg / L.

The results were as follows.
1. Treated water quality The BOD of treated water was 2 or less in both this method and the conventional method, and good treatment was carried out, and there was no significant difference in the water quality analysis items of the pond.
2. Power consumption In this method, since the bubbles were miniaturized, the amount of air blown to maintain the same dissolved oxygen concentration was ½ that of the comparative control series in which no ultrasonic device was installed. The power consumption related to air blowing was 3.6 KWH in this method and 7.2 KWH in the comparative control series. On the other hand, the power consumption of the entire ultrasonic equipment was 2.4 KWH, and the total power consumption was 6 KWH for this method and 7.2 KWH for the comparative control series, which was advantageous.
3. Amount of generated sludge The amount of excess sludge drawn when treating 1m ³ of sewage was 0.08kg in terms of dry solids, compared with 0.14kg in the comparative control series. Was confirmed.

  As described above, in this method, the effect of reducing the amount of generated sludge and the improvement of the oxygen dissolution efficiency can be achieved at the same time without providing a large facility installation space outside the reaction tank.

  The wastewater treatment apparatus of the present invention can be applied not only to a new installation but also to an existing wastewater treatment apparatus.

It is a schematic longitudinal cross-sectional view of the waste water treatment apparatus which is one Example of this invention. It is a schematic longitudinal cross-sectional view of the waste water treatment apparatus which is another Example of this invention.

Explanation of symbols

1. Blower 2. 2. Header tube Reaction tank 4. Air diffuser 5. Fine bubbles 6.7. Combined bubbles 8. Ultrasonic diaphragm 9. Bubbles refined again 10. 10. Ultrasonic transducer unit Ultrasonic transmitter (amplifier)
12 Activated sludge

Claims (4)

  In a wastewater treatment apparatus using activated sludge, an ultrasonic generation means is installed in a reaction tank equipped with an air diffuser.   The wastewater treatment apparatus according to claim 1, wherein the ultrasonic wave generation unit includes an ultrasonic vibration plate and an ultrasonic vibrator unit, and the ultrasonic vibration plate is installed in a bubble existing portion. .   The wastewater treatment apparatus according to claim 2, wherein the ultrasonic transducer unit has a watertight structure and is installed in a bubble existing portion together with the ultrasonic vibration plate.   A plurality of ultrasonic wave generating means are arranged in multiple stages in the vertical direction and / or the horizontal direction, and the horizontal center is shifted between the means adjacent to each other in the vertical direction. The wastewater treatment apparatus according to claim 2 or 3.

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