JP2008018309A - Apparatus for treating sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for treating sludge, in which sludge is satisfactorily dispersed, the reaction efficiency of treating ozone is increased and the modifying effect of sludge is enhanced. <P>SOLUTION: The apparatus for treating sludge is provided with: an ozone dissolving means for injecting and dissolving the ozone introduced from an ozonizer 8 in the organic sludge to be treated extracted from a final sedimentation basin 2; and an ozone reaction tank 7 in which the dissolved ozone is reacted with the organic sludge to be treated for a fixed time and undissolved ozone gas is separated from the treated sludge so that the organic sludge is modified. A restraint tank 11 for restraining the sludge, a first circulation line 12 in which the sludge in the restraint tank is pressurized by a pressure pump, cavitation is generated in the pressurized sludge by using a cavitation generator 14 and the cavitation-generated sludge is circulated to the restraint tank and a second circulation line 19 for circulating the treated sludge branched from the succeeding stage of the ozone reaction tank to the preceding stage of the restraint tank are arranged in the preceding stage of the ozone reaction tank 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sludge treatment apparatus for modifying sludge generated in a water treatment process using cavitation treatment and ozone reaction to reduce the amount of waste sludge.

As a method for treating sewage, the activated sludge method is widely used in various fields such as sewage treatment because of its high treatment capacity. Since this purification principle is based on the action of microorganisms decomposing and removing organic matter in the wastewater as feed, surplus sludge is generated as a result of the treatment. The generated sludge accounts for a large proportion of all industrial waste, and the residual capacity of the final disposal site is extremely small, which is a significant cost burden. Under such circumstances, it is desired to reduce surplus sludge as much as possible, and introduction of a sludge reduction method using various means is being studied.
In the conventional technology, after part of the excess sludge is pressurized and sprayed, it is reformed using ozone to improve biodegradability, and it is returned to the bioreactor to biooxidize and surplus sludge. The amount is reduced. (For example, see Patent Document 1)
The sludge reforming apparatus at this time is as shown in FIG. FIG. 3 is an explanatory view showing a conventional sludge treatment. In the figure, 1 is a biological reaction tank, 2 is a final sedimentation tank, 3 is a sludge treatment device, 4 is a pressure injection device, 7 is an ozone reaction tank, 8 is an ozone generator, 9 is an air diffuser, and 10 is a circulation pump. . The pressure injection device 4 includes a high-pressure pump 5 and a reactor 6.
A part of the sludge extracted from the final sedimentation basin 2 is pressurized by the high-pressure pump 5 of the pressure injection device 4 and injected into the reactor 6 for pressure injection processing. Since the activated sludge floc is dispersed by the pressure injection treatment, the ozone reaction efficiency can be increased, and the amount of ozone generated can be reduced. The sludge subjected to the pressure injection treatment is supplied to the ozone reaction tank 7. The ozonized gas generated by the ozone generator 8 is supplied into the tank through a diffuser tube 9 installed at the bottom of the ozone reaction tank 7, and is mixed with sludge and gas and liquid. The modified sludge that has been subjected to the ozone treatment is then returned to the biological reaction tank 1. At this time, since most of the MLSS component in the activated sludge is a biological organic substance, the activated sludge floc is dispersed by a physical action by pressure injection. Thereafter, due to the chemical action of ozone, which has strong oxidizing power, the cell walls and cell membranes constituting the organism are destroyed, and organic acids and sugars are released from the cells. By such an action, the sludge becomes highly biodegradable, and when it returns to the biological reaction tank, it is decomposed into inorganic substances and the sludge disappears.
Such a device is also considered as a means to promote the production of methane gas in facilities intended to produce methane gas through anaerobic digestion process of surplus sludge and effectively use it as biomass resources. ing.
JP 2004-275996 A

However, the conventional sewage treatment has a structure in which the physical solubilization performance is insufficient because it has a structure of flowing into the ozone reaction tank after passing through the pressure injection device. That is, the surplus sludge that flows in is physically solubilized only when it passes through the pressure injection device, and it is considered that the ozone treatment is performed with insufficient dispersion of the activated sludge flocs. Because.
The present invention has been made in view of such problems, and by installing a cavitation circulation treatment retention tank in front of the ozone reaction tank, sufficient sludge dispersion is achieved, and the ozone treatment reaction efficiency is high, and It aims at providing the sludge processing apparatus with the big reforming effect of sludge.

In order to solve the above problems, the present invention is configured as follows.
According to the first aspect of the present invention, ozone dissolving means for injecting and dissolving ozone introduced from an ozone generator into organic treated sludge drawn out from the final sedimentation basin, dissolved ozone and organic matter to be treated are fixed. In a sludge treatment apparatus that reacts for a time and separates undissolved ozone gas from treated sludge, and reforms the treated sludge, a retention tank that retains sludge in the previous stage of the ozone reaction tank; A first circulation line for introducing the sludge in the staying tank, generating cavitation by a pressure pump and a cavitation generator and circulating the sludge to the staying tank, and the treatment sludge branched from the subsequent stage of the ozone reaction tank, And a second circulation line for circulation to the previous stage.
The invention described in claim 2 is an ejector type ozone dissolving means.
According to a third aspect of the present invention, the ozone reaction tank and the retention tank have the same structure and are separated by an internal partition.
According to a fourth aspect of the present invention, the ozone reaction tank is provided with a third circulation line including a pressure pump for pressurizing sludge from the ozone reaction tank and the ozone dissolving means for dissolving ozone. .

According to the invention described in claim 1, since the first circulation line is provided in the staying tank, a high degree of vacuum is obtained inside the cavitation generator, and cavitation having a strong physical strength is generated in the liquid containing sludge. To do. At this time, the sludge cells passing through the space are crushed and finely decomposed by the impact force at the time of collapse of the bubbles generated by cavitation, and the viscosity is lowered. The cavitation treatment is performed cyclically through the residence tank, and the sludge cells are sufficiently finely decomposed. Further, by providing the second circulation line, the sludge after the ozone treatment can be cavitation treated again, and a synergistic effect is obtained.
According to the second aspect of the present invention, by providing an ejector, ozone is injected and mixed to cause contact and reaction between sludge and ozone, and the sludge is reformed by the strong chemical oxidation action of ozone. At this time, since sludge is finely decomposed by the previous cavitation treatment, the contact efficiency of ozone is increased and the sludge reforming effect is improved.
According to the invention described in claim 3, since the ozone reaction tank and the retention tank have the same structure and are divided by the internal partition, each treatment is performed in the same tank, and the synergistic effect can be obtained. .
According to invention of Claim 4, since the 3rd circulation line which has arranged ozone dissolution means was provided,
Since the number of circulations of the cavitation treatment and the ozone treatment can be individually set, it is possible to finely set the treatment conditions suitable for the target sludge.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a sludge treatment apparatus showing an embodiment of the present invention. In the figure, 11 is a staying tank for circulating and retaining sludge into which cavitation has been injected, and 12 is a first circulation line for supplying the staying tank 11 with cavitation generated by a circulation pump 13 and a cavitation generator 14. Reference numeral 16 denotes an ejector, 7 denotes an ozone reaction tank, and 19 denotes a second circulation line for returning the sludge branched from the ozone reaction tank 7 to the retention tank 1. 20 is a circulation pump, 15 is a pressurizing pump, and 18 is an exhaust ozone decomposing apparatus. In addition, since the thing with the same function attaches | subjects the same code | symbol, description of the previous thing is abbreviate | omitted.
The present invention is different from Patent Document 1 in that a residence tank for retaining sludge, a cavitation circulation treatment line comprising a pressurizing pump and a cavitation generator, an ozone And a cavitation circulation line.

Next, the operation of this embodiment will be described.
(1) First, the treated sludge is drawn into the retention tank 11. Then, the treated sludge pressurized by the circulation pump 13 is introduced into the cavitation generator 14. The interior of the cavitation generator 14 has an orifice structure, and cavitation occurs because the sludge to be treated is in a vacuum state when passing through the small-diameter portion. At this time, the components of sludge and fibrous structures combined in a floc form are subdivided and equalized by the impact force at the time of foam collapse generated by cavitation. At the same time, the cell wall and cell membrane of the sludge are destroyed, the intracellular enzymes are eluted and solubilized, and the viscosity of the liquid is also reduced. By repeating this operation in the first circulation line 12 and the staying tank 11, the contact area of the sludge to be treated for ozone injection in the subsequent stage increases, and the reaction efficiency increases. Here, since the optimum differential pressure before and after the cavitation generator 14 varies depending on the properties and viscosity of the treated sludge, it is set within the range of 0.1 to 1.5 MPa depending on the target conditions.
(2) Next, the treated sludge is introduced into the ejector 16 and mixed with the ozonized gas supplied from the ozone generator 8. Here, it comes into contact with ozone, which has a strong oxidizing power, and is chemically decomposed to be easily biodegradable. By setting the optimum differential pressure before and after the ejector 16 within a range of 0.05 to 0.2 MPa, efficient operation can be performed.
(3) Thereafter, the sludge is introduced into the ozone reaction tank 7. Here, gas-liquid separation from the exhaust ozone gas is performed, and the exhaust ozone gas is rendered harmless by the exhaust ozone decomposition device 18.
Moreover, the intensity of cavitation can be changed by controlling the operation output of the pressurizing pump.

FIG. 2 is an explanatory view of a sludge reforming apparatus showing Embodiment 2 of the present invention.
In the figure, 17 is a composite tank, 21 is a third circulation line, and 22 is a circulation pump.
The composite tank 17 has a retention tank 17a and an ozone reaction tank 17b having the same structure and is divided by an internal partition. The ejector 16 and the circulation pump 22 constitute a third circulation line 21. The functions of the retention tank 17a and the ozone reaction tank 17b of the composite tank 17 are the same as those of the retention tank 11 and the ozone reaction tank 7 of the first embodiment, and other configurations are also the same as those of the first embodiment (FIG. 1).
Cavitation circulation processing is performed in the pre-stage residence tank 17a of the partition plate in the composite tank 17, and ozone injection processing by the ejector 16 in the subsequent ozone reaction tank 17b extruded by the extrusion flow structure, gas / liquid of exhaust ozone gas and sludge. Separation processing is performed, and the exhaust ozone gas is rendered harmless by the exhaust ozone decomposing apparatus 18.

  The sludge treatment apparatus of the present invention efficiently reforms organic sludge and enhances biodegradability, so it is possible to treat sewage in general using microorganisms for removing organic matter such as public sewage and industrial wastewater such as chemical and food factories. In addition, methane gas is produced through an anaerobic digestion process of sludge, and this can be used effectively as a biomass resource and introduced into facilities for the purpose of reducing sludge associated therewith.

The block diagram of the sewage treatment system using the sludge treatment apparatus which shows Example 1 of this invention The block diagram of the sewage treatment system using the sludge treatment apparatus which shows Example 2 of this invention Configuration diagram showing a sewage treatment system using a conventional sludge treatment apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Biological reaction tank 2 Final sedimentation tank 3 Sludge processing apparatus 4 Pressure injection apparatus 5 High pressure pump 6 Reactor 7 Ozone reaction tank 8 Ozone generator 9 Aeration pipes 10, 13, 20, and 22 Circulation pump 11 Residence tank 12 First circulation line 14 Cavitation generator 15 Pressure pump 16 Ejector 17 Composite tank 17a Retention tank 17b Ozone reaction tank 18 Waste ozone decomposition device 19 Second circulation line 21 Third circulation line

Claims (4)

An ozone dissolution means that injects and dissolves ozone introduced from the ozone generator into the organic treated sludge extracted from the final sedimentation basin, reacts the dissolved ozone with the organic matter to be treated for a certain period of time, and generates undissolved ozone gas. In the sludge treatment apparatus which has an ozone reaction tank separated from the treated sludge and reforms the treated sludge,
A retention tank that retains sludge in the previous stage of the ozone reaction tank; a first circulation line that introduces sludge in the retention tank and generates cavitation by a pressure pump and a cavitation generator; A sludge treatment apparatus comprising a second circulation line for circulating the treated sludge branched from the rear stage of the reaction tank to the front stage of the staying tank.   The sludge treatment apparatus according to claim 1, wherein the ozone dissolving means is an ejector system.   The sludge treatment apparatus according to claim 1, wherein the ozone reaction tank and the staying tank have the same structure and are separated by an internal partition.   The said ozone reaction tank was provided with the 3rd circulation line by the pressurization pump which pressurizes the sludge from the said ozone reaction tank, and the said ozone melt | dissolution means to melt | dissolve ozone. Sludge treatment equipment.

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