JP4584958B2 - Sludge treatment equipment - Google Patents

Description

  The present invention relates to a sludge treatment apparatus, and more particularly, to an apparatus for treating sludge generated in a water treatment facility for treating sewage, industrial wastewater, livestock wastewater, and the like with ultrasonic waves.

  In general, biological treatment is used to treat wastewater such as sewage, industrial wastewater, and livestock wastewater, and a large amount of excess sludge is discharged with the removal of biological BOD components. This sludge is composed of inorganic suspended substances such as sand and organic suspended substances mainly composed of microorganisms. Recently, microorganisms in the sludge are physically, chemically, biologically or Proposals have been made to reduce sludge and to increase the efficiency of sludge treatment by crushing them using a combination of these methods and returning them to wastewater treatment.

As physical means to destroy microorganisms in sludge, ultrasonic treatment method that destroys microbial cells by the effect of cavitation that occurs when ultrasonic waves are applied to sludge, and destruction of cells by friction between mill and microorganisms A mill crushing method (see, for example, Patent Document 1) has been proposed. As chemical means, an ozone treatment method (for example, refer to Patent Document 2) or a chemical treatment method that destroys microorganism cells using a strong oxidizing action such as ozone or acid has been proposed. Furthermore, as a biological means, a method is proposed in which microbial cells are lysed and destroyed by an enzyme produced by a special microorganism (aerobic thermophilic bacterium) that grows under high temperature aerobic conditions (for example, see Patent Document 3). ing.
JP-A-11-156394 Japanese Patent No. 2973761 JP-A-9-253699

  Among these microbial cell destruction methods, sonication has been used in various fields, and there have been few reports on practical examples of sludge, although it has been attracting attention as a means of disrupting microbial cells. Not. One reason for this is that the ultrasonic vibrator installed in the sludge is heavily worn by contact with inorganic suspended solids such as sand contained in the sludge, and the life of the ultrasonic vibrator is shortened and replaced. Therefore, there is a problem that the running cost increases.

  Therefore, the present invention provides a long service life of the ultrasonic vibrator by avoiding contact between the ultrasonic vibrator and the inorganic suspended solid when the first settling sludge and surplus sludge generated in the water treatment process is subjected to ultrasonic treatment. An object of the present invention is to provide a sludge treatment apparatus capable of efficiently radiating ultrasonic waves to organic suspended solids in sludge.

To achieve the above object, the present invention provides a cylindrical ultrasonic treatment tank having a sludge inlet at the bottom and a sludge outlet at the top in a sludge treatment apparatus that irradiates the sludge generated in the water treatment process with ultrasonic waves. And an ultrasonic transducer is disposed at a portion on the upper side in the inclination direction of the ultrasonic treatment tank . It is also possible to install a plurality of the ultrasonic treatment tanks in series.

  According to the present invention, when ultrasonic treatment of sludge is performed, it is possible to avoid contact with the ultrasonic vibrator by inorganic suspended substances such as sand in the sludge, thereby reducing wear of the ultrasonic vibrator. Thus, it is possible to extend the life and improve the efficiency of ultrasonic irradiation with respect to the organic suspended substance in the sludge to be subjected to ultrasonic treatment.

  FIG. 1 is a system diagram showing an embodiment of the sludge treatment apparatus of the present invention. The sludge treatment apparatus 31 is a cylindrical ultrasonic treatment tank 32 having a sludge inlet 12 in the lower part and a sludge outlet 13 in the upper part. The ultrasonic transducer 33 is arranged, and the ultrasonic treatment tank 32 is inclined and installed so that the arrangement site of the ultrasonic transducer 33 is located on the upper side.

  In this way, by introducing sludge at an appropriate flow rate into the flow path in the ultrasonic treatment tank 32 inclined at an appropriate angle, the inorganic suspended material having a larger specific gravity than the organic suspended material is inclined. Since it flows along the lower side wall surface in the direction, it is possible to avoid contact between the ultrasonic vibrator 33 arranged on the upper side in the inclined direction and the inorganic suspended substance, and to reduce wear of the ultrasonic vibrator 33. To extend the service life. Further, similarly to the above, the ultrasonic irradiation efficiency is improved by increasing the concentration of the organic suspended substance around the ultrasonic vibrator 33. In addition, by appropriately setting the inclination angle of the ultrasonic treatment tank 32 and the flow rate of the sludge, the inorganic suspended solids can be precipitated at the bottom of the tank and extracted out of the tank.

  The diameter and inclination angle of the ultrasonic treatment tank 32 are set according to processing conditions such as flow velocity and conditions such as the properties of sludge to be processed. For example, the inclination angle is substantially horizontal with respect to the axis. Although it can be directed in the direction, it is usually in the range of 10 to 80 degrees, preferably 30 to 60 degrees. At this time, if the angle of inclination of the axis with respect to the horizontal plane exceeds 80 degrees, separation of the inorganic suspended substance and the organic suspended substance becomes difficult, and if it is less than 10 degrees, the inorganic suspended substance is precipitated at the bottom of the tank. It becomes difficult.

  It is also possible to change the inclination angle in the middle of the length direction of the ultrasonic treatment tank 32, and the position of the ultrasonic transducer 33 in the ultrasonic treatment tank 32 needs to be along the upper side wall surface in the inclination direction. There may be a position close to the axis. Furthermore, a sand settling facility for precipitating the inorganic suspended matter contained in the sludge and removing it from the sludge may be provided in the previous stage of the ultrasonic treatment tank 32. As the sand settling equipment, one having an appropriate structure can be used according to the properties and treatment amount of sludge, and equipment used in ordinary water treatment equipment can be used.

  Moreover, the conditions of the ultrasonic treatment in the sludge treatment apparatus of the present invention can be set in the same manner as in the conventional ultrasonic treatment. For example, the concentration (MLSS) of the sludge to be subjected to ultrasonic treatment is usually 20000 mg / L or less, preferably 15000 mg / L or less, particularly 10,000 mg / L or less. If the sludge concentration is too high, the ultrasonic wave will not be transmitted to the entire sludge and the desired treatment result will not be obtained. The refractory COD in the microorganisms is not preferable because it may shift to the liquid phase and adversely affect the wastewater treatment process.

  The frequency of the ultrasonic wave in the ultrasonic vibrator is 15 to 50 kHz, preferably 15 to 40 kHz, particularly 20 to 30 kHz. If this frequency is too low, a sufficient treatment effect cannot be obtained, and if it is too high, microorganisms in the sludge are destroyed, which is not preferable.

  The intensity of the ultrasonic wave is appropriately set according to the amount and concentration of sludge to be irradiated, but is generally 5 to 100 kWs / L, preferably 10 to 80 kWs / L, particularly 20-60 kWs / L is suitable. If the ultrasonic intensity is too small, a sufficient effect may not be obtained, and even if it is too high, an effect proportional to the intensity cannot be obtained.

  Each of these conditions, i.e., sludge concentration, ultrasonic frequency, ultrasonic intensity, and ultrasonic irradiation sludge amount, is an element of each condition. It can be appropriately changed to good conditions. Moreover, as shown in FIG. 1, the ultrasonic irradiation efficiency can be improved by installing a plurality of stages of relatively small ultrasonic treatment tanks in series.

It is a systematic diagram which shows one example of a sludge processing apparatus of this invention.

Explanation of symbols

  12 ... Sludge inlet, 13 ... Sludge outlet, 31 ... Sludge treatment device, 32 ... Ultrasonic treatment tank, 33 ... Ultrasonic vibrator

Claims (2)

In the sludge treatment equipment that irradiates the sludge generated in the water treatment process with ultrasonic waves , the sludge inflow port is installed at the bottom and the cylindrical sonication tank with the sludge outflow port at the top is inclined, and the ultrasonic treatment is performed. A sludge treatment apparatus characterized in that an ultrasonic vibrator is disposed at a portion on the upper side in the inclination direction of the tank . The sludge treatment apparatus according to claim 1, wherein the ultrasonic treatment tank is installed in a plurality of stages in series.

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