JP6261485B2 - Ozone treatment apparatus and sludge treatment method - Google Patents

Description

  The present invention relates to an ozone treatment apparatus and a sludge treatment method.

  Organic sludge generated in sewage treatment facilities includes primary sludge generated during the primary treatment of sewage, excess sludge generated during the secondary treatment of sewage, and digested sludge produced by digesting these sludges. . Patent document 1 is disclosing the method of performing ozone treatment and alkali treatment to sludge containing liquid. As a result, the decomposition of sludge is promoted to improve the recovery rate of phosphorus, and the volume of sludge is reduced.

JP-A-2005-219043

  In the treatment of the sludge-containing liquid containing sludge, it is required to sufficiently decompose the sludge and to efficiently separate the sludge and its decomposition products from the sludge-containing liquid with high accuracy. However, in the conventional sludge treatment as described in Patent Document 1, it is difficult to sufficiently progress the decomposition of the sludge. For this reason, it is required to establish a technique capable of efficiently separating sludge and its decomposition product from the sludge-containing liquid while sufficiently decomposing the sludge.

  Therefore, the present invention provides an ozone treatment apparatus and a sludge treatment method capable of efficiently separating sludge and its decomposition products from the sludge-containing liquid while sufficiently decomposing the sludge contained in the sludge-containing liquid. Objective.

  In one aspect, the present invention is an ozone treatment apparatus including a reaction tank that treats a sludge-containing liquid with ozone and separates the sludge-containing liquid into bubbles containing sludge decomposition products and water-containing drains. A foam layer containing foam, a liquid layer containing drain on the lower side of the foam layer, a first gas supply unit that supplies a gas containing ozone to the inside of the liquid layer, and an inside of the foam layer An ozone treatment apparatus is provided that includes a liquid supply unit that supplies a sludge-containing liquid.

  In the reaction tank of the above-described ozone treatment apparatus, the liquid supply unit supplies the sludge-containing liquid to the inside of the foam layer containing foam. The sludge containing liquid supplied to the inside of the foam layer flows down along the foam surface of the foam layer. On the other hand, a part of ozone contained in the gas supplied from the first gas supply unit to the inside of the liquid layer reacts with sludge contained in the liquid layer, and the other part of the ozone rises to the foam layer by raising the liquid layer. Moving. At this time, most of the ozone that has moved to the foam layer is dissolved in the foam main body and the water adhering to the surface. On the foam main body and the surface thereof, this dissolved ozone efficiently reacts with the sludge contained in the sludge-containing liquid to generate a decomposition product. Thus, since the sludge and ozone contained in the sludge-containing liquid can efficiently contact on the foam main body and the surface of the foam layer, the reaction between the sludge and ozone sufficiently proceeds and the sludge can be decomposed efficiently. It is guessed.

  In addition, the sludge contained in the sludge-containing liquid supplied in the foam layer, and the decomposition product generated by the decomposition of the sludge adhere to the foam containing the sludge decomposition product by the action of liquid crosslinking force, etc. At the same time, the foam layer is raised and discharged from the upper part of the reaction vessel. On the other hand, the water contained in the sludge-containing liquid has a large specific gravity and does not adhere to the foam as much as the sludge and its decomposition products, so it flows downward and enters the liquid layer. In this way, sludge and its decomposition products and water can be separated with high accuracy.

  The liquid supply unit may be configured to supply the sludge-containing liquid to the inside of the foam layer on the liquid layer side from the center in the height direction of the foam layer. As a result, the water adhering to the surface of the foam main body flows down sufficiently while the foam ascends the reaction vessel, so that the sludge and its decomposition products can be sufficiently concentrated in the foam layer. Therefore, it is possible to separate water and sludge and their decomposition products with higher accuracy.

  The ozone treatment apparatus includes a stirring tank on the downstream side of the reaction tank, and the stirring tank stirs and breaks the bubbles discharged from the upper part of the reaction tank so that sludge contained in the bubbles reacts with ozone. It may be configured. By providing a stirring tank for stirring and breaking bubbles, the volume of the foam layer in the reaction tank can be reduced, and the reaction tank can be miniaturized. In addition, the sludge treatment process can be shortened.

  The first gas supply unit may include a diffused gas composed of a porous material, and may be configured to supply gas from the diffused gas. Thereby, since the fine bubble-like gas is supplied from the first gas supply unit, the contact area between the gas and the liquid in the liquid layer can be increased. Moreover, since the foam in the foam layer is also reduced as a whole, the surface area of the entire foam is increased, and the contact efficiency between the sludge-containing liquid and the dissolved ozone can be further increased.

  The ozone treatment apparatus may include a second gas supply unit that supplies a gas containing ozone to the stirring tank. Thereby, the sludge contained in the foam reacts with ozone to sufficiently reduce the sludge and to effectively use the decomposed product.

  In another aspect, the present invention provides a sludge treatment method in which a sludge-containing liquid is treated with ozone in a reaction tank and separated into bubbles containing sludge decomposition products and water-containing drains, and formed in the reaction tank. Supplying a sludge-containing liquid into the foam layer containing bubbles, and supplying a gas containing ozone into the liquid layer formed in the reaction tank and containing drain under the foam layer; A sludge treatment method is provided.

  In the sludge treatment method described above, the sludge-containing liquid is supplied into the foam layer containing foam. The sludge containing liquid supplied to the inside of the foam layer flows down along the foam surface of the foam layer. On the other hand, the gas containing ozone supplied into the liquid layer ascends the liquid layer and moves to the foam layer. At this time, most of the ozone that has moved to the foam layer is dissolved in the foam main body and the water adhering to the surface. On the foam main body and the surface thereof, this dissolved ozone efficiently reacts with the sludge contained in the sludge-containing liquid to generate a decomposition product. Thus, since the sludge-containing liquid and dissolved ozone can efficiently contact on the foam main body and the surface of the foam layer, it is speculated that the reaction between the sludge and ozone proceeds sufficiently, and the sludge can be decomposed efficiently. The

  In addition, the sludge contained in the sludge-containing liquid supplied in the foam layer, and the decomposition product generated by the decomposition of the sludge adhere to the foam containing the sludge decomposition product by the action of liquid crosslinking force, etc. At the same time, the foam layer is raised and discharged from the upper part of the reaction vessel. On the other hand, since the water contained in the sludge-containing liquid has a large specific gravity and is not as strong as the sludge and its decomposed product in terms of adhesion to the foam body, it flows down and enters the liquid layer. In this way, sludge and its decomposition products and water can be separated with high accuracy.

  The sludge-containing liquid may be supplied to the inside of the foam layer on the liquid layer side from the center in the height direction of the foam layer. As a result, while the foam containing sludge decomposition products rises in the reaction tank, water adhering to the surface of the foam main body flows down sufficiently, and the sludge and its decomposition products are sufficiently concentrated in the foam layer. Can do. Therefore, water and sludge and their decomposition products can be separated with higher accuracy.

  In the above-described sludge treatment method, in the agitation tank on the downstream side of the reaction tank, the foam containing the sludge decomposition product discharged from the upper part of the reaction tank is stirred to break up bubbles, and the sludge contained in the foam reacts with ozone. You may have a process. Thus, the whole process can be shortened by mechanically breaking the foam containing the sludge decomposition product. Moreover, the exclusive volume of the foam layer in a reaction tank can be made small by providing a stirring tank.

  A gas containing ozone may be supplied to the stirring tank. Ozone is dissolved in the foam body and the water accompanying it. In addition to this, by further supplying a gas containing ozone, the reaction between the sludge contained in the foam and ozone is further promoted, and the sludge can be sufficiently reduced. Thereby, the effective utilization of the sludge decomposition product can be further promoted.

  According to the present invention, it is possible to provide an ozone treatment apparatus and a sludge treatment method capable of efficiently separating sludge and its decomposition products from a sludge-containing liquid while sufficiently decomposing sludge contained in the sludge-containing liquid. it can.

FIG. 1 is a diagram illustrating an embodiment of an ozone treatment apparatus. FIG. 2A and FIG. 2B are schematic views showing an enlarged cross section of the foam contained in the foam layer. It is a figure which shows an example of the sludge treatment system to which the ozone treatment apparatus of FIG. 3 is applied. FIG. 4 is a graph showing the relationship between the height of the reaction tank and the dissolved ozone concentration in the liquid phase in Example 1 and Comparative Example 1. FIG. 5 is a graph showing the relationship between the height of the reaction tank and the concentration of evaporation residue (TDS) in Example 1 and Comparative Example 1. FIG. 6 is a graph showing the relationship between the height of the reaction tank and the viscosity of the liquid phase in Example 1 and Comparative Example 1. FIG. 7 is a graph showing the relationship between the concentration of evaporation residue (TDS) and the viscosity in Example 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings depending on cases. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram illustrating an embodiment of an ozone treatment apparatus. The ozone treatment apparatus 100 includes a reaction tank 10 and a stirring tank 30 provided on the downstream side of the reaction tank 10. A liquid supply unit 12 that supplies a sludge-containing liquid containing sludge and water to the reaction tank 10 is connected to the reaction tank 10. A liquid layer 40 made of drain containing water is formed in the lower part of the reaction vessel 10. A foam layer 20 including a plurality of bubbles 21 is formed on the upper part of the reaction vessel 10.

A first gas supply unit 14 that supplies a gas containing ozone into the liquid layer 40 is provided in the lower part of the reaction tank 10. The decomposition product produced by decomposing sludge with ozone has viscosity. For this reason, when gas is supplied from the first gas supply unit 14, bubbles 21 are formed on the liquid layer 40. The first gas supply unit 14 may have a diffused gas composed of a porous material at the tip. By supplying a gas containing ozone from such a diffused gas, a fine bubble-like gas is supplied to the liquid layer 40. Thereby, the contact area between the gas and the drain of the liquid layer 40 can be increased. Examples of the gas containing ozone include oxygen gas containing ozone. The concentration of ozone in the gas is, for example, 20 to 100 mg-O ₃ / L.

  By supplying a gas containing ozone to the liquid layer 40, ozone and sludge contained in the liquid layer 40 can be reacted efficiently. If the gas bubbles supplied from the first gas supply unit are made fine, the bubbles 21 in the bubble layer 20 can also be reduced. Thereby, the entire surface area of the bubbles 21 is increased, and the contact efficiency between the sludge-containing liquid and ozone can be further increased.

  In the reaction tank 10, the volume ratio of the foam layer 20 to the liquid layer 40 may be, for example, 2 to 8, or 3 to 7. If this volume ratio becomes too small, the concentration of sludge in the foam layer 20 does not proceed sufficiently, and the amount of water flowing out to the stirring tank 30 tends to increase. On the other hand, if the volume ratio becomes too large, the reaction between ozone and sludge does not proceed sufficiently in the liquid layer 40 and the amount of sludge accompanying the drain discharged from the pipe 18 tends to increase.

  The liquid supply unit 12 is configured such that a sludge-containing liquid can be supplied into the foam layer 20 formed in the reaction tank 10. The liquid supply part 12 will not be specifically limited if it is a structure which can supply a sludge containing liquid in the inside of the foam layer 20. FIG. For example, the liquid supply unit 12 may be configured by an opening provided on the side wall of the reaction vessel 10 and a pipe connected to the opening. In some other embodiments, the liquid supply unit 12 includes a tip portion and a pipe portion that is connected to the tip portion and supplies a sludge-containing liquid to the tip portion, and the tip portion has a diameter of the stirring tank 30. The structure may be such that it is disposed in the center of the direction and the sludge-containing liquid is discharged from an opening provided at the tip.

  The liquid supply part 12 may be arrange | positioned so that the sludge containing liquid may be supplied to the inside of the foam layer 20 of the liquid layer 40 side rather than the center in the height direction of the foam layer 20. That is, when the height of the foam layer 20 is H, sludge is formed inside the foam layer 20 between the position of the interface between the foam layer 20 and the liquid layer 40 and the position of the height 0.5H from the interface. The liquid supply unit 12 may be provided so as to supply the contained liquid. As a result, the water adhering to the foam main body can flow down sufficiently while the foam 21 rises in the reaction tank 10. Therefore, the concentration of sludge and its decomposition products can be increased in the foam layer 20. As a result, water and sludge and their decomposition products can be separated with high accuracy.

  The liquid supply unit 12 contains sludge in the foam layer 20 having a height of 0.1H to 0.4H, preferably 0.1H to 0.3H from the interface between the foam layer 20 and the liquid layer 40. It may be provided to supply liquid. As a result, the reaction between the sludge and the dissolved ozone can be sufficiently advanced in the foam layer 20 while sufficiently flowing water downward in the foam layer 20. Thereby, water, sludge, and the decomposition product thereof can be separated with higher accuracy.

  The sludge-containing liquid is, for example, sludge water generated at a sewage treatment plant, and contains water and sludge. The contents of water and sludge in the sludge-containing liquid are, for example, 30 to 80% by weight and 20 to 70% by weight, respectively. The sludge includes, for example, suspended substances (SS) and liquid organic substances (evaporation residue: TDS). The suspended substance (SS) contains an inorganic substance and a volatile organic substance (VSS component).

  The concentration of suspended matter (SS) can be measured according to “14.1 Suspended matter” of JIS K0102: 2013. Specifically, the sludge-containing liquid is filtered through a 1 μm mesh filter, and the residue is dried at 105 to 110 ° C. for measurement. The concentration of the evaporation residue (TDS) can be measured according to “14.2 Total evaporation residue” of JIS K0102: 2013. Volatile organic matter (VSS) is what disappears when the suspended matter (SS) is heated at 600 ° C. ± 25 ° C. for 0.5 hours (disappearance). The concentration of the volatile organic substance (VSS) is determined using JIS K0102: 2013 "14. Suspended substances and evaporation residues" and "14.1 Suspended substances" using the sample obtained by heating under the above heating conditions. "Can be measured in accordance with.

  In the reaction tank 10, the volatile organic matter (VSS) contained in the sludge-containing liquid reacts with ozone to produce an evaporation residue (TDS) that is a sludge decomposition product. That is, when the volatile organic substance (VSS) reacts with ozone, the cell wall of the cell which is the volatile organic substance (VSS) is decomposed, and an evaporation residue (TDS) is generated. Through such a reaction, sludge can be reduced in the reaction tank 10 by reducing suspended solids (SS).

  In the reaction tank 10, the decomposition of the sludge proceeds sufficiently. Specifically, the TDS elution rate calculated by the following formula (1) can be 20% by weight or more, preferably 25% by weight or more. In the reaction tank 10, suspended solids can be efficiently separated from the sludge-containing liquid. Specifically, the SS transfer rate calculated by the following formula (2) can be 90% by weight or more, preferably 95% by weight or more.

TDS dissolution rate (% by weight) = [TDS ₁₆ -TDS ₁₂ x foam flow rate / sludge containing liquid flow rate]] x 100 / VSS ₁₂ (1)
SS transfer rate _{(wt%) = [SS 16 + TDS} 16 -TDS 12 × bubble flow / flow rate of the sludge-containing _{liquid] × 100 / SS 12 (2} )

In the formulas (1) and (2), TDS ₁₆ is the flow rate per unit time of TDS contained in the foam discharged from the upper part of the reaction tank 10, and TDS ₁₂ is the sludge containing liquid supplied to the reaction tank 10. It is a flow rate per unit time of TDS included. VSS ₁₂ is a flow rate per unit time of VSS contained in the sludge-containing liquid supplied to the reaction tank 10. SS ₁₆ is the flow rate per unit time of SS contained in the foam discharged from the upper part of the reaction tank 10, and SS ₁₂ is the flow rate per unit time of SS contained in the sludge-containing liquid supplied to the reaction tank 10. is there. “Bubble flow rate” is the flow rate per unit time of foam discharged from the upper part of the reaction tank 10, and “Flow rate of sludge containing liquid” is the flow rate per unit time of the sludge containing liquid supplied to the reaction tank 10. It is. All the flow rates are flow rates based on weight.

  FIG. 2 is a schematic diagram showing an enlarged cross section of the foam 21 included in the foam layer 20. As shown in FIGS. 2 (A) and 2 (B), the foam 21 is composed of a foam main body 22, sludge particles 24 adhering to the periphery of the foam main body 22, and a decomposition product 26 generated by decomposition of the sludge particles 24. And water 28 attached around the foam body 22. The foam body 22 is formed by surrounding a gas containing ozone supplied from the first gas supply unit 14 to the liquid layer 40 with a liquid organic substance contained in sludge and a sludge decomposition product. The sludge particle 24 is, for example, SS, and the decomposition product 26 is, for example, TDS. The decomposition product 26 is generated by a reaction between ozone and the sludge particles 24 and may be integrated with the foam main body 22 after the generation.

  Water 28 adheres on the surface of the foam main body 22. The water 28 rises in the foam layer 20 together with the foam body 22. In the water 28 and the foam main body 22, ozone is dissolved. At least a part of the sludge particles 24 contained in the sludge-containing liquid flowing down along the surface of the foam 21 adheres to the surface of the foam main body 22. In the foam layer 20 of the reaction tank 10, the dissolved ozone and the sludge particles 24 can efficiently contact with each other on the surface of the foam main body 22, so that the decomposition reaction of the sludge particles 24 proceeds sufficiently. In addition, the sludge particles 24 adhering to the surface of the foam main body 22 react with dissolved ozone while the foam layer 20 is raised. Thereby, the density | concentration of the decomposition product 26 increases toward the upper direction of the foam layer 20. As shown in FIG.

  FIG. 2A shows the bubbles 21 of the bubble layer 20 at a position higher than that in FIG. As the foam 21 ascends the foam layer 20, the water 28 attached to the foam body 22 falls due to the action of gravity. On the other hand, the sludge particles 24 and the decomposition product 26 rise together with the foam main body 22 while adhering to the surface of the foam main body 22 due to actions such as liquid crosslinking force and surface tension. For this reason, as shown in FIGS. 2 (A) and 2 (B), the higher the position of the foam layer 20, the more the water 28 decreases and the concentration of the sludge particles 24 and the decomposition products 26 increases. Thus, in the foam layer 20, the sludge particles 24 and the decomposition product 26 are concentrated, and the sludge and the decomposition product and water can be separated with high accuracy.

  As shown in FIG. 1, the upper part of the reaction tank 10 and the upper part of the stirring tank 30 are connected by a pipe 16. The bubbles 21 are discharged from the reaction tank 10 by the pipe 16 connected to the upper part of the reaction tank 10 and introduced into the stirring tank 30. The stirring tank 30 includes a stirring shaft and a stirring blade attached to the stirring shaft, and includes a stirrer 32 configured to be rotatable around the stirring shaft.

  In the stirring tank 30, the stirrer 32 is operated to break the bubbles 21 and obtain a concentrate 29. By providing such a stirrer 32, the bubbles 21 are mechanically broken, so that the size of the ozone treatment apparatus 100 as a whole can be made compact. Moreover, reaction with the sludge particle | grains 24 contained in the foam | bubble 21 and dissolved ozone can be accelerated | stimulated by stirring. The obtained concentrate 29 is discharged to the outside through a pipe or the like (not shown).

  The stirring tank 30 is connected to a second gas supply unit 34 that supplies a gas containing ozone. Similarly to the first gas supply unit 14, the second gas supply unit 34 may have a diffused gas made of a porous material at the tip. By stirring the foam 21 with the stirrer 32 while supplying the gas containing ozone from the second gas supply unit 34, the sludge particles 24 contained in the foam 21 can react with ozone.

  The ozone treatment apparatus 100 can reduce the exclusive volume of the foam layer 20 in the reaction tank 10 by including the stirring tank 30 that stirs and breaks the foam 21. Therefore, the reaction tank 10 can be downsized. In addition, the sludge treatment process can be shortened. However, it is not essential to provide the stirring tank 30.

  A pipe 18 for discharging drain is connected to the bottom of the reaction tank 10. The drain containing water contained in the sludge-containing liquid is discharged from the reaction tank 10 through the pipe 18. In the reaction tank 10, since the sludge and its decomposition products are concentrated and discharged from the upper pipe 16, the concentration of sludge and its decomposition products in the drain can be sufficiently reduced. The height of the liquid layer 40 in the reaction tank 10 can be controlled by adjusting the amount of drain discharged from the pipe 18. The drain may be sent to, for example, a water treatment device in a sewage treatment plant.

  The liquid layer 40 preferably contains sludge and its decomposition products from the viewpoint of stably generating the bubbles 21. However, if the concentration of sludge and its decomposition product in the liquid layer 40 becomes too high, the concentration of sludge and its decomposition product in the drain discharged from the pipe 18 tends to increase. For this reason, it is preferable to make the viscosity of the liquid layer 40 into a predetermined range from a viewpoint of forming the foam layer 20 stably, reducing the density | concentration of the sludge in a drain, and its decomposition product.

  The viscosity of the liquid layer 40 may be, for example, 1 to 10 cP or 1 to 5 cP. By maintaining the viscosity of the liquid layer 40 in the above range, the reaction tank 10 can be operated continuously and stably even if the properties of the sludge-containing liquid supplied to the reaction tank 10 fluctuate. . The viscosity of the foam layer 20 is preferably higher than the viscosity of the liquid layer 40, and may be, for example, 5 to 80 cP.

  The viscosity of the liquid layer 40 can be controlled by adjusting the supply amount of the sludge-containing liquid supplied from the liquid supply unit 12. For example, when the viscosity of the liquid layer 40 is likely to fall below the target range, the supply amount of the sludge-containing liquid from the liquid supply unit 12 is increased. As a result, the amount of sludge flowing down to the liquid layer 40 increases and the viscosity of the liquid layer 40 increases. On the other hand, when the viscosity of the liquid layer 40 is likely to exceed the target range, the supply amount of the sludge-containing liquid from the liquid supply unit 12 is decreased. As a result, the amount of sludge that flows down to the liquid layer 40 decreases, and the viscosity of the liquid layer 40 decreases.

  A control unit that controls the supply amount of the sludge-containing liquid based on the measurement result of the viscosity of the liquid layer 40 may be provided. By providing such a control part, even if the properties of the sludge-containing liquid fluctuate, the reaction tank 10 can be continuously operated sufficiently stably. An online analyzer for measuring the viscosity may be provided in the liquid layer 40 to automatically control the supply amount of the sludge-containing liquid. Alternatively, the liquid layer 40 may be appropriately sampled to measure the viscosity of the sample, and the supply amount of the sludge-containing liquid may be manually controlled based on the measurement result as necessary.

  FIG. 3 is a diagram illustrating an example of a sludge treatment system to which the ozone treatment apparatus 100 is applied. The sludge treatment system 1 is applied to, for example, a sewage treatment plant. The sludge treatment system 1 includes a water treatment device 50 for treating sewage, an ozone treatment device 100 and a digestion fermentation device 70 for treating sludge-containing liquid generated in the water treatment device 50 to reduce the volume of sludge, and sludge treatment. A sludge treatment device 60 that performs dehydration and drying is provided.

  In the ozone treatment apparatus 100, solid fuel and phosphorus fertilizer can be efficiently produced from sewage by separating sludge and its decomposition products and water while decomposing sludge contained in the sludge-containing liquid. The concentrate 29 obtained by the ozone treatment apparatus 100 may be supplied to the digestion fermentation apparatus 70 to produce methane. The drain containing water obtained by the ozone treatment apparatus 100 may be supplied to the water treatment apparatus 50. In addition, the use of the ozone treatment apparatus 100 is not limited to the sludge treatment system 1 of FIG. 3, It can apply to the various systems which process a sludge containing liquid.

  Next, one embodiment of the sludge treatment method will be described below. The sludge treatment method of the present embodiment may be performed using the ozone treatment apparatus 100 described above. The sludge treatment method of the present embodiment is a sludge treatment method in which a sludge-containing liquid is treated with ozone in the reaction tank 10 to separate bubbles containing sludge decomposition products and water-containing drains. A first step of supplying a sludge-containing liquid into the foam layer 20 including the formed foam 21 by the liquid supply unit 12, and a liquid layer including drain on the lower side of the foam layer 20 formed in the reaction tank 10. 40 includes a second step of supplying a gas containing ozone by the first gas supply unit 14. In addition to these steps, in the agitation tank 30 on the downstream side of the reaction tank 10, the bubbles 21 discharged from the upper part of the reaction tank 10 are agitated and broken to react sludge contained in the bubbles 21 with ozone. You may have a 3rd process. The first step, the second step, and the third step can be performed simultaneously in parallel.

  It is preferable that the sludge-containing liquid is supplied to the inside of the foam layer 20 on the liquid layer 40 side from the center in the height direction of the foam layer 20. Thereby, the quantity of the water contained in the foam discharged | emitted from the upper part of the reaction tank 10 can fully be reduced, and sludge and its decomposition product can fully be concentrated. In the stirring tank 30, the sludge contained in the foam may react with ozone contained in the foam to obtain a decomposition product, or a gas containing ozone is separately supplied to the stirring tank 30 and is contained in the ozone and the foam. A sludge may be obtained by reacting with sludge. The concentrate 29 containing the unreacted sludge particles and the decomposition product thereof obtained in the stirring tank 30 may be treated by the sludge treatment apparatus 60, or may be used as a raw material for solid fuel or phosphorus fertilizer.

  The sludge treatment method of the present embodiment can be performed based on the description of the ozone treatment apparatus 100 described above. That is, since the explanation content about the ozone treatment apparatus 100 can be applied to the sludge treatment method, duplicate description is omitted.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  The content of the invention will be described in detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
The sludge containing liquid generated from the sewage water treatment apparatus was supplied to the ozone treatment apparatus 100 shown in FIG. 1 to perform ozone treatment. The height of the reaction vessel 10 was 2.5 m. The liquid supply unit 12 supplies the sludge-containing liquid from the position of the reaction tank 10 at a height of 0.65 m at a flow rate of 2 to 5 L / min, and oxygen gas containing ozone from the first gas supply unit 14 (ozone concentration: 60 mg). -O ₃ / L) was fed continuously to the reactor 10 at a flow rate of 10～60L / min. Foam was continuously discharged from the pipe 16 connected to the upper part of the reaction tank 10 and drain was discharged from the pipe 18 connected to the lower part of the reaction tank 10. The drainage amount was adjusted, and the boundary surface between the liquid layer 40 and the foam layer 20 was adjusted to a height of 0.5 m from the bottom of the reaction vessel 10.

After the reaction vessel 10 was in a steady operation state, sampling was performed at different height positions, and the dissolved ozone concentration in the liquid phase of each sample was measured. The dissolved ozone concentration was measured using a pack test (registered trademark) ozone [WAK-O ₃ ] (Kyoritsu Riken). The measurement results are plotted in FIG. In FIG. 4, the white circle plot is the measurement result of Example 1. The rightmost plot in FIG. 4 shows the properties of the fluid sample that has flowed over the reaction vessel 10. As shown in FIG. 4, also in the foam layer 20, it was confirmed that ozone is present in the liquid phase in the range of 0.5 to 1.5 mg-O ₃ / L. From this, it was confirmed that the foam layer 20 is an environment in which the reaction between ozone and sludge can proceed.

  The concentration of evaporation residue (TDS) in the liquid phase of the sample collected as described above was measured. The measurement results are plotted in FIG. In FIG. 5, the white circle plot is the measurement result of Example 1. The rightmost plot in FIG. 5 shows the properties of the fluid sample that has flowed over the reaction vessel 10. In Example 1, the concentration of the evaporation residue (TDS) is increased above the supply height (0.65 m) of the sludge-containing liquid from the liquid supply unit 12. It was confirmed that the evaporation residue (TDS) was concentrated in the height direction. And it was confirmed from the upper part of the reaction tank 10 that the bubble containing 0.5 weight% of evaporation residue (TDS) is discharged | emitted.

  The viscosity in the liquid phase of the sample collected as described above was measured using a commercially available viscometer. The measurement results are plotted in FIG. In FIG. 6, the white circle plots are the measurement results of Example 1. The rightmost plot in FIG. 6 shows the properties of the fluid sample that has flowed over the reaction vessel 10. In Example 1, it was confirmed that the variation in viscosity (inclination) in the height direction of the reaction vessel 10 was small and the viscosity gradually increased. This indicates that the decomposition and concentration of sludge progresses gradually in the entire reaction tank 10, and it can be said that the entire reaction tank 10 is effectively used.

  FIG. 7 is data obtained by plotting the relationship between the concentration of evaporation residue (TDS) on the horizontal axis and the viscosity of the liquid phase on the vertical axis. In FIG. 7, the left plot is the data of the liquid layer 40, and the right plot is the data of the foam layer 20. From the data in FIG. 7, it was confirmed that the viscosity increases as the concentration of evaporation residue (TDS) increases. Therefore, by sampling and measuring the viscosity of the liquid phase, it is possible to estimate the operating state of the reaction vessel 10 and the concentration distribution of evaporation residue (TDS). In addition, it was confirmed that the viscosity can be used as an index for grasping the operation status and the operation management based on the measurement result of the viscosity can be performed.

The gas phase ozone concentration in the foam layer 20 was measured at heights of 0.6 m, 1.1 m, and 2.4 m from the bottom of the reaction vessel 10. As a result, the ozone concentration was 0 to ₃ mg-O ₃ / L at any position. These values were significantly lower than the ozone concentration in the oxygen gas supplied from the first gas supply unit 14. This is considered to be because ozone is dissolved in the liquid phase of the foam layer 20 and consumed in the reaction with sludge in the liquid layer 40. The ozone concentration in the gas phase was measured using a commercially available ultraviolet absorption gas phase ozone concentration meter (manufactured by Shibata Kagaku Co., Ltd., apparatus name: OZM-5000).

  In Example 1, the TDS elution rate during steady operation was 25 to 30% by weight, and the SS transfer rate was 85 to 100% by weight.

(Comparative Example 1)
Except that the amount of drain discharged from the bottom of the reaction vessel 10 was adjusted so that the boundary surface between the liquid layer 40 and the foam layer 20 was 1.0 m above the bottom of the reaction vessel 10. Then, the reaction vessel 10 was operated. In Comparative Example 1, the sludge-containing liquid was supplied into the liquid layer 40 of the reaction tank 10.

  In the same manner as in Example 1, sampling was performed at different height positions, and the dissolved ozone concentration, evaporation residue (TDS) concentration, and viscosity in the liquid phase of each sample were measured. These measurement results are shown in FIGS. In each figure, the black square plot is the measurement result of Comparative Example 1.

  As shown in FIG. 4, in Comparative Example 1, the amount of dissolved ozone in the liquid phase of the foam layer 20 was less than that in Example 1. And as shown in FIG. 5, the density | concentration of the evaporation residue (TDS) hardly changed in the foam layer 20. From this, it is considered that in the comparative example 1, the decomposition of the sludge is not progressing so much. As shown in FIG. 6, in Comparative Example 1, the viscosity of the liquid phase was significantly increased near the interface between the liquid layer 40 and the foam layer 20. This indicates that the sludge decomposition reaction locally proceeds in the reaction tank 10 and the entire reaction tank 10 cannot be effectively used.

  In Comparative Example 1, the TDS elution rate during steady operation was 16-18% by weight, and the SS transfer rate was 80-87% by weight. Both the TDS elution rate and SS transfer rate were lower than in Example 1.

DESCRIPTION OF SYMBOLS 1 ... Sludge processing system, 10 ... Reaction tank, 12 ... Liquid supply part, 14 ... 1st gas supply part, 16, 18 ... Piping, 20 ... Foam layer, 21 ... Foam, 22 ... Foam body, 24 ... Sludge particle, 26 ... Decomposition product, 28 ... Water, 29 ... Concentrate, 30 ... Stirrer tank, 32 ... Stirrer, 34 ... Second gas supply unit, 40 ... Liquid layer, 50 ... Water treatment device, 60 ... Sludge treatment device, 70 ... digestive fermentation equipment, 100 ... ozone treatment equipment.

Claims (9)

An ozone treatment apparatus comprising a reaction tank that treats sludge-containing liquid with ozone and separates it into bubbles containing sludge decomposition products and water-containing drains,
In the reaction tank, a foam layer containing the foam and a liquid layer containing the drain below the foam layer are formed,
A first gas supply unit that supplies a gas containing ozone to the inside of the liquid layer, and a liquid supply unit that supplies the sludge-containing liquid to the inside of the foam layer,
The liquid supply unit supplies the sludge-containing liquid inside the foam layer of the liquid layer side than the center in the height direction of the foam layer, ozone processing device. A stirring tank is provided on the downstream side of the reaction tank,
The stirring tank, the by-breaking by agitating the foam top is discharged from the reaction vessel, the reaction of sludge and ozone respectively included in the foam, ozone treatment apparatus according to claim 1. An ozone treatment apparatus comprising a reaction tank that treats sludge-containing liquid with ozone and separates it into bubbles containing sludge decomposition products and water-containing drains,
In the reaction tank, a foam layer containing the foam and a liquid layer containing the drain below the foam layer are formed,
A first gas supply unit that supplies a gas containing ozone to the inside of the liquid layer, and a liquid supply unit that supplies the sludge-containing liquid to the inside of the foam layer,
The first gas supply unit is an ozone processing apparatus having a diffused gas composed of a porous material and supplying the gas from the diffused gas. An ozone treatment apparatus comprising a reaction tank that treats sludge-containing liquid with ozone and separates it into bubbles containing sludge decomposition products and water-containing drains,
In the reaction tank, a foam layer containing the foam and a liquid layer containing the drain below the foam layer are formed,
A first gas supply unit for supplying a gas containing ozone into the liquid layer; a liquid supply unit for supplying the sludge-containing liquid into the foam layer;
A stirring tank downstream of the reaction tank ;
And a second gas supply unit for supplying a gas containing ozone in the stirred tank,
The said stirring tank is an ozone processing apparatus which stirs and breaks the foam discharged from the upper part of the said reaction tank, and makes sludge and ozone respectively contained in the said foam react . The said liquid supply part is an ozone treatment apparatus of Claim 3 or 4 which supplies the said sludge containing liquid to the inside of the said foam layer of the said liquid layer side rather than the center in the height direction of the said foam layer . In a reaction tank, a sludge treatment method for treating sludge-containing liquid with ozone to separate bubbles containing sludge decomposition products and water-containing drains,
Supplying the sludge-containing liquid into the foam layer containing the foam formed in the reaction vessel;
Supplying a gas containing ozone into the liquid layer containing the drain below the foam layer formed in the reaction vessel, and
The sludge-containing liquid, wherein also the center in the height direction of the foam layer is supplied to the inside of the foam layer of the liquid layer side, sludge treatment method. In a stirred vessel downstream of the reactor, said to cell breakage by stirring the foam discharged from the top of the reaction vessel, comprising the step of reacting a sludge and ozone contained in the foam, in claim 6 The described sludge treatment method. In a reaction tank, a sludge treatment method for treating sludge-containing liquid with ozone to separate bubbles containing sludge decomposition products and water-containing drains,
Supplying the sludge-containing liquid into the foam layer containing the foam formed in the reaction vessel ;
Supplying a gas containing ozone into the liquid layer containing the drain below the foam layer formed in the reaction vessel;
In the stirring tank on the downstream side of the reaction tank, the foam discharged from the upper part of the reaction tank is stirred to break the foam, and the sludge contained in the foam reacts with ozone. supplying a gas containing ozone in the stirred tank, in the process, sludge treatment method. The sludge treatment method according to claim 8, wherein the sludge-containing liquid is supplied to the inside of the foam layer on the liquid layer side from the center in the height direction of the foam layer.

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