JP2005230588A - Treating method for foaming scum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method for foaming scum by which the foaming scum can be easily liquefied and treated without requiring addition of large-scale equipment concerned with a water cleaning function and without using chemicals, or the like. <P>SOLUTION: As the treating method for the foaming scum, in activated sludge treatment which cleans impurities in water by using aerobic bacteria, the foaming scum 11 produced by activity of actinomycetes is moved to another vessel 12 and physical force (fall of the vessel 12, application of vibration and application of shock by blow) is applied to the vessel 12 from the outside to defoam and liquefy the foaming scum 11 in the vessel 12. Then, liquefied sludge is blended with sludge to be discharged as excess sludge outside a system and obtained sludge mixture is subjected to thickening dehydration by a dehydrator 15 and is treated as industrial waste (dehydrated cake). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for treating foam scum generated by the activity of actinomycetes in activated sludge treatment.

  In activated sludge treatment that purifies impurities in wastewater using aerobic microorganisms, wastewater is mixed with activated sludge in an aeration tank and aerated, and after aerobic treatment decomposes organic solids in wastewater, aeration treatment The sludge mixture afterwards is guided to the sedimentation basin, where it separates into activated sludge and non-biodegradable substance solids and water, and the supernatant water is discharged as treated water, while a part of the solids is in the aeration tank. It is returned to the factory and used as activated sludge, and the remainder is discharged as excess sludge.

  By the way, in the aeration tank, the oxygen necessary for actinomycetes, which are aerobic bacteria, is sufficiently supplied, so that the actinomycetes may grow abnormally. When the concentration of actinomycetes in activated sludge increases, actinomycetes release biologically derived surfactant-like substances and float on the water surface together with bubbles. At this time, some of the sludge flocs are released from these bubbles and rays. Since they adhere to the fungus discharge and float, they become foam scum and accumulate on the surface of the aeration tank.

  Foaming scum flows into the sedimentation pond from the aeration tank and does not separate into solid and liquid in the sedimentation pond, causing deterioration of the water quality, blowing off in the wind, and overflowing from the aeration tank when foaming is severe. And may contaminate the surrounding environment.

  Therefore, a scum removing device such as a scum skimmer for removing foamed scum is provided in the aeration tank and the settling basin. In addition, as a method for treating foamed scum, there is a defoaming watering method in which water is sprinkled on a floating foamed scum to physically break the scum. In addition, as a method for biologically suppressing actinomycetes, a sludge residence time control method for discharging sludge out of the system as a sludge at a speed higher than the growth rate of actinomycetes (see, for example, Patent Document 1) has been conventionally known. ing.

  In recent years, various proposals have been made to suppress the removal or generation of foam scum. For example, various sterilization means (injection of ozone, irradiation of ultraviolet rays, addition of chlorine-based disinfectant, ultrasonic wave, etc.) against scum water discharged from a scum skimmer from foamed scum generated in an aeration tank or a sedimentation pond of an activated sludge treatment facility (Refer to Patent Document 2) or before returning sludge from the sedimentation basin to the aeration tank, it is introduced into another return sludge aeration tank to intentionally generate and remove scum and return A method has been proposed in which the concentration of actinomycetes in sludge is reduced and the sludge is returned to the aeration tank (see Patent Document 3).

  Furthermore, in the defoaming water spray method, a method of lysing actinomycetes by directly adding a hydrolase to the defoaming water (Patent Document 4), adding a scum-removing agent to the activated sludge treatment system, A method for suppressing the generation (see Patent Document 5) has also been proposed.

JP-A-8-309383 JP-A-6-262167 JP-A-8-299980 Japanese Patent Application Laid-Open No. 8-112591 JP-A-11-267681

  However, in the conventional method, a large-scale facility for carrying out the method is added, so that the cost of the apparatus is increased, or the treated water is contaminated because a chemical such as an antifoaming agent or a disinfectant is used. There was a problem.

  The present invention has been made in view of the above-mentioned problems, and its intended process is that foaming can be easily performed without requiring the addition of large-scale equipment related to the water purification function and without using chemicals or the like. An object of the present invention is to provide a method for treating foamed scum capable of liquefying scum and treating it.

  In order to achieve the above object, the invention described in claim 1 is directed to an activated sludge treatment for purifying impurities in water using an aerobic microorganism, and the foamed scum generated by the activity of actinomycetes is transferred to another container. By applying a physical force from the outside, the foamed scum in the container is defoamed and liquefied.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the container is dropped and the physical force is applied to the container from the outside.

  According to a third aspect of the present invention, in the first aspect of the invention, the container is vibrated and the physical force is applied to the container from the outside.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the container is subjected to impact by hitting and the physical force is applied to the container from the outside.

  Invention of Claim 5 mixes the sludge liquefied in the said container in the invention in any one of Claims 1-4 with the sludge discharged | emitted out of the system as surplus sludge, and dehydrates the mixed sludge It is characterized in that it is concentrated and dehydrated by a machine or dehydrated and dried by heating.

  According to the experiment of the present inventor, the foamed scum generated by the activity of actinomycetes in the activated sludge treatment is transferred to another container, and physical force (impact by dropping, vibration, impact by impact, etc.) is externally applied to the container. Was added, it was confirmed that the foam scum in the container was defoamed and liquefied.

  Therefore, according to the first to fourth aspects of the present invention, the foam scum can be easily formed by simply applying physical force from the outside to the container without the need for additional equipment or using chemicals. It can be liquefied and treated.

  Further, according to the invention described in claim 5, the sludge previously liquefied in the container can be concentrated and dehydrated without being foamed by the dehydrator together with the sludge discharged out of the system as surplus sludge. The dehydrated cake can be treated as harmless industrial waste. Of course, it can be dehydrated and dried by heating.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram of an activated sludge treatment facility for carrying out the method of the present invention. In FIG. 1, reference numeral 1 denotes an aeration tank. The aeration tank 1 is connected to sewage, drainage, etc. via an inflow pipe 2. Raw water is introduced.

  In the aeration tank 1, biological treatment is performed by the activated sludge method while aeration is performed by air jetted from the air diffuser 3, and organic substances in the raw water are decomposed. The air diffuser 3 is supplied with compressed air from the compressor 4.

  Thus, the sludge mixed solution after aeration treatment in the aeration tank 1 is introduced into the sedimentation basin 6 through the transfer pipe 5, where activated sludge and non-biodegradable solids (referred to as separated sludge) are introduced. The supernatant water is discharged from the drain pipe 7 as treated water, while the separated sludge is taken out from the separated sludge discharge pipe 8, and a part thereof is returned from the return pipe 9 to the aeration tank 1 as return sludge. Returned for biological treatment. The remaining separated sludge is discharged as excess sludge.

  By the way, in the aeration tank 1, since oxygen required for actinomycetes which are aerobic bacteria is sufficiently given, the actinomycetes grow abnormally. When the concentration of actinomycetes in activated sludge increases, actinomycetes release biologically derived surfactant-like substances and float on the water surface with bubbles, but at this time, some of the sludge flocs adhere to the bubbles. Therefore, they become foamed scum 11 and accumulate on the surface of the aeration tank 1.

  Thus, in the present embodiment, the foamed scum 11 floating in layers on the water surface in the aeration tank 1 is scooped with a handle not shown or the like and transferred to another container 12, and this container 12 Added physical force to the outside.

  Here, as a specific example in which a physical force is applied to the container 12 from the outside, the methods shown in FIGS.

  That is, the example shown in FIG. 2 is a method of dropping the container 12 on the ground and applying an impact to the container 12 from the outside. In the example shown in FIG. 3A, the container 12 is vibrated up and down by the rotation of the eccentric cam 13. FIG. 2B shows a method in which the container 12 is fixed to the vibrator 14 and a vertical vibration is applied thereto. Further, the example shown in FIG. 4 is a method of hitting the container 12 and applying an impact thereto. As a specific method, an operation such as kicking the container 12 with a foot or hitting the container 12 with a stick or the like. Is included.

  By the way, according to the experiment of the present inventor, it was confirmed that the foam scum 11 in the container 12 was defoamed and liquefied by applying an external impact to the container 12 in the example shown in FIG. Specifically, the foam scum, which initially had a volume of 100 L (liter), was reduced to 5 L by repeated three drops and became a liquid without foaming.

  Therefore, according to the present embodiment, a physical force is simply applied to the container 12 from the outside without adding a large-scale facility related to the water purification function and without using a medicine or the like. Simply, the foamed scum 11 can be liquefied and treated. Specifically, as shown in FIG. 5A, for example, substantially the same amount of foamed scum 11 is transferred into a container 12 having a volume of 100 L, and the container 12 is externally applied by any of the methods shown in FIGS. When a physical force was applied, as shown in FIG. 5B, the foamed scum 11 in the container 12 was liquefied and its volume was reduced to 5 L, that is, 1/20.

  Such a device can be installed separately from the equipment related to the water purification function, and can be removed when not in use, regardless of the installation location. Of course, the water purification function is not affected.

  In the present embodiment, as shown in FIG. 1, in order to liquefy the foamed scum 11 in the container 12, the excess sludge discharged from the sedimentation basin 6 is mixed, and the mixed sludge is dehydrated by a dehydrator 15. It can be concentrated and dehydrated. Therefore, the foamed scum 11 generated in the aeration tank 1 can be finally dehydrated together with excess sludge to be converted into a dehydrated cake that is a solid, and this dehydrated cake can be treated as harmless industrial waste. it can. Moreover, dehydration drying can also be performed by heating.

  The present invention has high applicability as a method for treating foam scum generated by the activity of actinomycetes in the treatment activated sludge treatment.

It is a schematic diagram of the activated sludge processing equipment for enforcing the method of the present invention. It is a figure which shows the method of dropping a container as an example which applies a physical force to the container from the outside. (A), (b) is a figure which shows the method of giving a vibration to a container as an example which applies a physical force to the container from the outside. It is a figure which shows the method of giving the impact by impact to a container as an example which applies a physical force to the container from the outside. (A) is a figure which shows the state in the container before applying a physical force to a container, (b) is a figure which shows the state in a container after applying a physical force to a container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Inflow pipe 3 Aeration pipe 4 Compressor 5 Transfer pipe 6 Settling pond 7 Drain pipe 8 Separation sludge discharge pipe 9 Return pipe 10 Sludge floc 11 Foam scum 12 Container 13 Eccentric cam 14 Vibrator 15 Dehydrator

Claims (5)

  In activated sludge treatment that purifies impurities in water using aerobic microorganisms, the foam scum generated by the activity of actinomycetes is transferred to another container, and physical force is applied to the container from the outside. A method for treating foamed scum, wherein the foamed scum is defoamed and liquefied.   The foam scum treatment method according to claim 1, wherein the container is dropped and the physical force is applied to the container from outside.   2. The foam scum treatment method according to claim 1, wherein the physical force is applied to the container by applying vibration to the container.   2. The foam scum treatment method according to claim 1, wherein the container is subjected to impact by striking and the physical force is applied to the container from the outside.   The sludge liquefied in the container is mixed with sludge discharged out of the system as surplus sludge, and the mixed sludge is dehydrated and dried by concentrating and dehydrating with a dehydrator or heating. The processing method of the foaming scum in any one of -4.

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