JP3776091B2 - Organic sludge treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treatment apparatus for organic sludge generated when biological wastewater containing organic matter is biologically treated.
[0002]
[Prior art]
Biological treatment such as the activated sludge method is mainly used in purification treatment of wastewater containing organic matter. However, in such biological treatment, there is a problem that a considerable amount of excess sludge is generated during the treatment. Conventionally, excess sludge has been reduced in volume by dehydration, drying, and incineration, but the processing costs are rising due to the shortage of final disposal sites.
[0003]
As a method for reducing the volume of this organic surplus sludge, a method in which the organic sludge is solubilized by ozone oxidation and then biologically decomposed by an aerobic microorganism has been proposed (for example, Patent Document 1). , 2, 3, 4).
[0004]
[Patent Document 1]
JP-A-6-206088 [Patent Document 2]
Japanese Patent Laid-Open No. 9-122679 [Patent Document 3]
JP 2002-28686 A [Patent Document 4]
Japanese Patent Laid-Open No. 10-216688
[Problems to be solved by the invention]
However, as described in Patent Documents 1 to 4, in order to reduce excess sludge simply by ozone oxidation, a large amount of ozone gas is actually required. This is because a large amount of ozone is consumed to improve sludge BOD (biochemical oxygen demand) and COD (chemical oxygen demand).
[0006]
Therefore, in order to carry out the conventional sludge treatment method described above, a large ozone generator for supplying a large amount of ozone gas is required, so that a huge cost is required for the sludge treatment.
[0007]
Accordingly, an object of the present invention is to provide an organic sludge treatment apparatus capable of completely decomposing and reducing the volume of organic sludge with a smaller amount of ozone gas.
[0008]
[Means for Solving the Problems]
The organic sludge treatment apparatus of the present invention includes an electrolysis tank that electrolyzes water to be treated containing organic sludge using an electrode that generates chlorine gas in water when energized, and water to be treated that has been treated by the electrolysis tank. A means for injecting ozone gas, and a reaction tank for oxidization reaction of the water to be treated, which includes a means for refining the water to be treated into which ozone has been injected.
[0009]
When water to be treated containing organic sludge is electrolyzed using an electrode that generates chlorine gas in water when energized, chlorine gas is generated from the electrode and hypochlorous acid is produced in the water to be treated. Since hypochlorous acid has a strong oxidizing power, the organic sludge in the treated water is oxidatively decomposed and BOD and COD in the treated water are improved. In addition, by injecting ozone gas into the water to be treated whose BOD and COD have been improved in advance as described above, even with a small amount of ozone gas, the organic sludge in the water to be treated is oxidized and decomposed by the ozone gas. Is called. At this time, OH radicals having very strong oxidizing power are generated in the water to be treated. Furthermore, since the treated water is refined by the refinement means, the contact area between the organic sludge in the treated water and ozone gas is expanded, so that the oxidative decomposition of the organic sludge is further promoted, The volume of the activated sludge is reduced.
[0010]
At this time, by pressurizing the inside of the reaction tank, more ozone gas or the like can be dissolved in the water to be treated and reacted with organic sludge in the water to be treated for oxidative decomposition. In addition, the excess gas in the reaction layer is returned to the water to be treated in the electrolysis tank and dissolved, so that the excess gas causes oxidative decomposition in the electrolysis tank.
[0011]
Here, an electrode covered with a platinum-based material or a ruthenium-based material can be used. Electrodes coated with platinum-based or ruthenium-based materials generate chlorine with very low voltage energy consumption.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration diagram of an organic sludge treatment apparatus according to an embodiment of the present invention. As shown in FIG. 1, the organic sludge treatment apparatus in the present embodiment is an electrolysis tank 1 for electrolyzing water to be treated containing organic sludge, and injected into water to be treated that has been electrolyzed by the electrolysis tank 1. An ozone generator 2 for generating ozone gas, a reaction tank 3 for oxidizing the treated water into which ozone gas has been injected, a flow rate adjusting tank 4 for adjusting the flow rate of the treated water, and a press machine 5 for compressing sludge. And a dissolution tank 6 for dissolving excess gas in the reaction tank 3 in the water to be treated.
[0013]
The electrolysis tank 1 is separated into two tanks by a diaphragm 10. Of these two tanks, the latter tank 1b includes an electrode plate 11 in which cathodes and anodes are alternately arranged. A current converted into a direct current by the rectifier 12 is applied to the electrode plate 11. The electrode plate 11 is a metal electrode in which a coating layer of a platinum-based material is formed on a titanium substrate by thermal decomposition (firing). Here, the platinum-based material is a material containing platinum (Pt) and includes a composite material obtained by blending pure platinum and platinum with ruthenium or other materials. Moreover, what coated the metal base | substrate other than titanium can also be used.
[0014]
Of the two tanks separated by the diaphragm 10, the preceding tank 1 a has a total electric conductivity (hereinafter referred to as “EC”) 13 and a redox potential (hereinafter referred to as “ORP”) total 14. A hydrogen ion exponent (hereinafter referred to as “pH”) total 15 is provided. From the EC measured by the EC meter 13, the salt concentration in the tank 1a can be known. By the ORP measured by the ORP meter 14, it is possible to determine whether the water quality in the tank 1a is in an oxidized state or a reduced state. Depending on the pH measured by the pH meter 15, it is possible to determine whether the water quality in the tank 1a is acidic or alkaline. Moreover, the front tank 1a is provided with a saline supply device 16 for supplying concentrated saline.
[0015]
The ozone generator 2 is a conventionally known ozone generator. The ozone generator 2 is connected in the middle of a pipe 7 a that connects the tank 1 b downstream of the electrolysis tank and the reaction tank 3. A pump 8a is provided in the middle of the pipe 7a. The ozone gas generated by the ozone generator 2 is injected from the tank 1b in the subsequent stage of the electrolysis tank 1 into the water to be treated sucked up by the pump 8a.
[0016]
The reaction tank 3 is a tank for reacting the water to be treated after the electrolysis treatment with the ozone gas injected into the water to be treated. The inside of the reaction tank 3 is pressurized by about 0.15 to 0.3 MPa. The reaction tank 3 includes a nozzle 30 shown in FIG. 2 as a refining means for refining the water to be treated introduced from the electrolysis tank 1. The nozzle 30 is provided at the inlet of the reaction tank 3. 2A is a front view of the nozzle 30, FIG. 2B is a longitudinal sectional view, and FIG.
[0017]
As shown in FIG. 2B, the nozzle 30 has an inner / outer double structure including an inner nozzle 31 and an outer shell 32. The pipe 7 a is connected to the inner nozzle 31. As shown in FIGS. 2B and 2C, the tip of the inner nozzle 31 opens downward. The opening 33 of the inner nozzle 31 is provided with a plurality of claws 34 a and 34 b that protrude alternately inside and outside the inner nozzle 31. The water to be treated discharged from the inner nozzle 31 is refined by colliding with the inner claw 34a. A part of the water to be treated discharged from the inner nozzle 31 is refined by colliding with the outer claw 34b when diffusing outward from the inner nozzle 31.
[0018]
The outer shell 32 includes a plurality of slits 35 as shown in FIG. The slit 35 has a shape in which irregularities are alternately arranged like a saw tooth. The treated water discharged from the inner nozzle 31 is further refined by colliding with irregularities such as saw teeth when passing through the slit 35. Further, a scattering plate 36 for colliding and scattering the water to be treated discharged from the inner nozzle 31 is provided below the outer shell 32 and directly below the inner nozzle 31. The peripheral edge of the scattering plate 36 has a shape that is slightly warped upward so as to go to the slit 35 of the outer shell 32 after the water to be treated discharged from the inner nozzle 31 collides. The water to be treated discharged from the inner nozzle 31 collides with the scattering plate 36 and is scattered and further refined by passing through the slit 35.
[0019]
In addition, the reaction tank 3 includes a water level sensor 37. The pump 8 a is controlled based on the detection result of the water level sensor 37. Thereby, the water level in the reaction tank 3 is kept constant.
[0020]
The flow rate adjusting tank 4 is connected to the reaction tank 3 by a pipe 7b. The pipe 7b is connected to the lower part of the reaction tank 3 (a position below the water level sensor 37). The flow rate adjusting tank 4 stores the treated water supplied by the pipe 7b, and adjusts the flow rate of the treated water sent to the press machine 5 through the pipe 7c by the pump 8b. A flocculant supply device 9 for adding the flocculant to the treated water is provided in the middle of the pipe 7c. The press 5 compresses the treated water sent from the flow rate adjusting tank 4 and added with the flocculant, and separates it into sludge and water.
[0021]
The dissolution tank 6 dissolves surplus gas taken out from the upper side of the reaction tank 3 through the pipe 7d into the water to be treated taken out from the tank 1b at the rear stage of the electrolysis tank 1 through the pipe 7e provided with the pump 8c. . The inside of the dissolution tank 6 is pressurized by about 0.15 to 0.3 MPa as in the reaction tank 3. The excess gas after dissolution is supplied to the tank 1a in the previous stage of the electrolysis tank 1 through the pipe 7f.
[0022]
The volume reduction processing of organic sludge (hereinafter simply referred to as “sludge”) by the organic sludge treatment apparatus having the above configuration will be described below.
[0023]
Water to be treated containing sludge after biological treatment of wastewater containing organic matter is sucked up by the pump 8d and supplied to the tank 1a in the previous stage of the electrolysis tank 1. Here, based on the measurement result of EC by the EC meter 13 of the tank 1a (salt concentration in the tank 1a), the concentrated saline or dilution water from the saline supply device 16 is appropriately supplied into the tank 1a. The salt concentration is adjusted to be suitable for electrolysis in the tank 1b.
[0024]
In the subsequent tank 1b, the direct current is passed through the electrode plate 11 by the rectifier 12, whereby the water to be treated is electrolyzed. Here, chlorine gas is generated from the electrode plate 11, and hypochlorous acid is generated in the water to be treated. Since this hypochlorous acid has a strong oxidizing power, the sludge in the water to be treated is oxidized and decomposed, and the BOD and COD in the water to be treated are improved.
[0025]
Thus, the water to be treated with improved BOD and COD is supplied to the reaction tank 3 from the tank 1b at the rear stage of the electrolysis tank 1 by the pump 8a. At this time, ozone gas generated by the ozone generator 2 is injected into the water to be treated in the middle of the pipe 7a. The water to be treated into which ozone gas has been injected is supplied into the reaction tank 3 in a state of being miniaturized by the nozzle 30.
[0026]
In the reaction tank 3, sludge in the water to be treated is oxidatively decomposed by ozone gas. Since the water to be treated is refined by the nozzle 30 as described above, the contact between the sludge in the water to be treated and the ozone gas is prevented. More actively, the oxidative decomposition of sludge is further promoted. Here, since ozone is a very unstable substance, there are a substance that reacts directly with an organic substance and decomposes into oxygen, and a substance that self-decomposes in water, as shown below.
[0027]
(1) Direct reaction O ₃ + M (organic) → MO + O ₂
(2) Self-decomposing O ₃ + H ₂ O → HO ₃ ⁺ + OH ^{−
_{HO 3 + + OH - → 2HO}} 2 ·
O ₃ + HO ₂ · → OH · + 2O ₂
[0028]
As shown in (2), ozone decomposes with water (hydrolysis) to form hydroperoxy radicals (HO _2. ), And further reacts with ozone to generate OH radicals (OH.). That is, OH radicals having very strong oxidizing power are generated in the water to be treated in the reaction tank 3. Therefore, the sludge in the water to be treated is almost completely oxidized and decomposed by the OH radicals. In addition, since the to-be-processed water oxidized and decomposed | disassembled by ozone gas in this reaction tank 3 is in the state by which BOD and COD were improved beforehand by electrolyzing in the electrolysis tank 1, The amount of ozone gas used for oxidative decomposition is small.
[0029]
Moreover, in the organic sludge treatment apparatus in this embodiment, since the inside of the reaction tank 3 is pressurized, more ozone gas etc. are melt | dissolved in to-be-processed water, and it reacts with the sludge in to-be-processed water, and oxidatively decomposes. . Moreover, since the surplus gas of the ozone gas in the reaction layer 3 is dissolved in the water to be treated in the electrolysis tank 1 in the dissolution tank 6 and returned to the electrolysis tank 1, the surplus gas causes the excess gas in the electrolysis tank 1. But oxidative degradation takes place.
[0030]
Thus, the water to be treated which has been almost completely oxidized and decomposed is sent to the flow rate adjusting tank 4 through the pipe 7b. And when sending out from the flow control tank 4 to the press machine 5 by the piping 7c, the flocculant is added to the to-be-treated water by the flocculant supply device 9. Thereby, the sludge remaining in the water to be treated is aggregated and separated into sludge and water by the press machine 5. The separated water is discharged to the final aeration tank through the electric valve 8f.
[0031]
As described above, in the organic sludge treatment apparatus in the present embodiment, after improving the BOD and COD of water to be treated containing sludge by chlorine gas generated by electrolysis, ozone gas is injected to perform oxidative decomposition. Even with a small amount of ozone gas, sludge can be reduced in volume by almost completely oxidizing and decomposing. The amount of ozone gas used in the organic sludge treatment apparatus of the present embodiment is about 20 to 30% compared to a conventional excess sludge decomposition apparatus. Moreover, since the electrode plate 11 used in the electrolysis tank 1 generates chlorine with very low electric energy consumption, the organic sludge treatment apparatus in the present embodiment consumes little power.
[0032]
Moreover, in the organic sludge treatment apparatus in the present embodiment, the ORP meter 14 provided in the electrolysis tank 1 can determine whether the water quality is in an oxidized state or a reduced state. It can be judged that oxidation has progressed under the influence of hypochlorous acid. If this oxidation has progressed too much, for example, by reducing the amount of concentrated saline solution added by the saline solution supply device 16, adjustments such as reducing the ability of electrolysis are performed, and an optimal oxidation state is achieved. It is possible to maintain.
[0033]
Furthermore, in the organic sludge treatment apparatus in the present embodiment, it is possible to determine whether the water quality is acidic or alkaline by the pH meter 15 provided in the electrolysis tank 1. The generation of hypochlorous acid by electrolysis occurs at a pH of 4 to 6, that is, on a weakly acidic side. Therefore, if the pH is high (alkaline side), for example, by adjusting the amount of concentrated saline to be added by the saline supply device 16, adjustment is made to a weakly acidic region where the generation rate of hypochlorous acid is higher. It can be performed.
[0034]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0035]
(1) An electrolysis tank that electrolyzes water to be treated containing organic sludge using an electrode that generates chlorine gas in water by energization, and means for injecting ozone gas into the water to be treated treated by the electrolysis tank; And BOD for treating water containing sludge by chlorine gas generated by electrolysis by having a refining means for refining treated water into which ozone gas has been injected and having a reaction tank for oxidizing the treated water Since the ozone gas is injected and oxidative decomposition is performed after improving the COD, the sludge can be almost completely oxidized and decomposed to reduce the volume even with a small amount of ozone gas.
[0036]
(2) Since the inside of the reaction tank is pressurized, more ozone gas and the like can be dissolved in the water to be treated and reacted with organic sludge in the water to be treated, so that it can be oxidized and decomposed more. The sludge can be efficiently oxidized and decomposed to reduce the volume.
[0037]
(3) Since the means for dissolving the surplus gas in the reaction tank in the water to be treated in the electrolysis tank is provided, the oxidative decomposition is performed in the electrolysis tank by the surplus gas. Can be oxidatively decomposed to reduce the volume.
[0038]
(4) Since the electrode is coated with a platinum-based material or a ruthenium-based material, chlorine can be generated with very low electric energy consumption, so that an organic sludge treatment apparatus with low power consumption can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an organic sludge treatment apparatus in an embodiment of the present invention.
FIGS. 2A and 2B are diagrams showing details of a nozzle provided in a reaction tank, wherein FIG. 2A is a front view, FIG. 2B is a longitudinal sectional view, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrolysis tank 1a First tank 1b Second tank 2 Ozone generator 3 Reaction tank 4 Flow rate adjustment tank 5 Press machine 6 Dissolution tank 7a, 7b, 7c, 7d, 7e, 7f Piping 8a, 8b, 8c, 8d Pump 8f Motorized valve 9 Flocculant supply device 10 Diaphragm 11 Electrode plate 12 Rectifier 13 EC meter 14 ORP meter 15 pH meter 16 Saline solution supply device 30 Nozzle 31 Inner nozzle 32 Outer part 33 Openings 34a, 34b Claw 35 Slit 36 Scatter plate 37 Water level sensor

Claims (4)

An electrolysis tank for electrolyzing water to be treated containing organic sludge using an electrode that generates chlorine gas in water when energized;
Means for injecting ozone gas into the water to be treated treated by the electrolysis tank;
An apparatus for treating organic sludge, comprising a refining means for refining the water to be treated into which the ozone gas has been injected, and a reaction tank for oxidizing the water to be treated. 2. The organic sludge treatment apparatus according to claim 1, wherein the inside of the reaction tank is pressurized. The organic sludge treatment apparatus according to claim 1 or 2, further comprising means for dissolving surplus gas in the reaction tank in water to be treated in the electrolysis tank. The organic sludge treatment apparatus according to any one of claims 1 to 3, wherein the electrode is coated with a platinum-based material or a ruthenium-based material.

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