JP2018008235A - Ozone treatment device and sludge treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ozone treatment device capable of separating sludge, a degraded article thereof and water at high accuracy while decreasing volume of the sludge by degrading the sludge sufficiently.SOLUTION: An ozone treatment device 100 has: a reaction tank 10 for treating ozone with a sludge-containing liquid and separating the same into a foam layer 20 containing a degraded article of the sludge and a liquid layer 40 containing water; a liquid supply part for supplying the sludge-containing liquid to inside of the foam layer 20; and a gas supply part 50 for supplying a gas containing ozone to inside of the liquid layer 40 at a lower side of the foam layer 20. The gas supply part supplies a gas so that a supply amount of ozone is 30 mg or more to 1 g of a floating matter contained in the sludge of the sludge-containing liquid and gas superficial velocity of the reaction tank is 0.0035 m/sec. or more.SELECTED DRAWING: Figure 1

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 requested | required to establish the technique which can fully decompose sludge and can obtain sludge and its decomposition product from sludge containing liquid.

  Accordingly, in one aspect, the present invention provides an ozone treatment apparatus capable of sufficiently degrading sludge to reduce the sludge and separating sludge and its decomposition products from water with high accuracy. For the purpose. Moreover, this invention provides the sludge processing method which can isolate | separate sludge and its decomposition product, and water with high precision while fully decomposing sludge and reducing sludge in another side surface. For the purpose.

  In one aspect, the present invention is an ozone treatment apparatus comprising a reaction tank that treats a sludge-containing liquid with ozone and separates the sludge-containing liquid into a foam layer containing a sludge decomposition product and a liquid layer containing water. A liquid supply unit that supplies sludge-containing liquid to the inside, and a gas supply unit that supplies gas containing ozone to the inside of the liquid layer below the foam layer. Provided is an ozone treatment apparatus for supplying gas so that the amount of ozone supplied to 1 g of suspended matter contained in sludge is 30 mg or more and the gas superficial velocity of a reaction tank is 0.0035 m / second or more.

  In the reaction tank of the above-described ozone treatment apparatus, the liquid supply unit supplies the sludge-containing liquid into the foam layer containing the sludge decomposition product. 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 the ozone contained in the gas supplied from the gas supply unit to the inside of the liquid layer reacts with the sludge contained in the liquid layer, and the other part of the ozone moves up 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 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 sufficiently decomposed. .

  The sludge contained in the sludge-containing liquid supplied in the foam layer and the decomposition product produced by the decomposition of the sludge adhere to the foam containing the sludge decomposition product due to the action of liquid crosslinking force, etc. The bed is raised and discharged from the top 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.

  The gas supply unit supplies gas so that the amount of ozone supplied to 1 g of suspended matter contained in the sludge of the sludge-containing liquid is 30 mg or more and the superficial velocity in the reaction tank is 0.0035 m / second or more. . Thereby, while sludge is fully decomposed | disassembled and sludge is reduced, sludge and its decomposition product, and water can be isolate | separated with sufficient high precision.

  The liquid supply unit has a height of the entire interior of the reaction tank of H, and is higher than the liquid level of the sludge-containing liquid stored in the reaction tank when the inner bottom of the reaction tank is used as a reference, and 0.2H It is preferable to supply the sludge-containing liquid at a position between ˜0.7H. As a result, the decomposition rate of sludge and the separation accuracy between sludge and its decomposition products and water can be achieved at a sufficiently high level.

  The ozone treatment apparatus includes a pressure measuring unit that measures the pressure of the foam layer, a supply flow rate of the sludge-containing liquid supplied from the liquid supply unit based on the pressure measured by the pressure measuring unit, and a gas from the gas supply unit. And a control unit that adjusts at least one of the supply flow rate and the drain discharge flow rate from the reaction vessel.

  The pressure measurement unit is installed at a position higher than the liquid level of the sludge-containing liquid so that the pressure of the foam layer can be measured. The pressure in the foam layer depends on the supply pressure of the gas containing ozone from the gas supply unit, the height of the foam layer, the liquid level height of the sludge-containing liquid, and the like. These values affect the reaction between ozone and sludge. Therefore, the control unit can adjust the pressure of the foam layer to a predetermined range by adjusting at least one of the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, and the discharge flow rate of the drain from the reaction tank. . Thereby, the decomposition efficiency of sludge can be maintained within a predetermined range.

  The ozone treatment device includes a pressure measuring unit that measures the pressure of the foam layer, an antifoaming tank that is connected to the reaction tank and that breaks bubbles by stirring the foam discharged from the reaction tank with an agitator. You may provide the antifoamer supply part which supplies an antifoamer to a tank. In this case, based on the pressure measured by the pressure measurement unit, the control unit supplies the sludge-containing liquid supply flow rate, the gas supply flow rate, the drain discharge flow rate from the reaction tank, the rotation speed of the stirrer, and the power consumption. You may be comprised so that at least 1 of the supply flow volume of the antifoamer from a foaming agent supply part may be adjusted.

  In the case of providing a defoaming tank, the pressure in the foam layer is determined in addition to the supply pressure of the gas containing ozone from the gas supply unit, the height of the foam layer, and the liquid level height of the sludge-containing liquid. It depends on the separation rate of sludge and exhaust gas. Therefore, the control unit supplies the sludge-containing liquid supplied from the liquid supply unit based on the pressure measured by the pressure measuring unit, the gas supply flow from the gas supply unit, and the drain discharge flow from the reaction tank. By adjusting at least one of the rotational speed of the stirrer and the supply flow rate of the antifoaming agent from the antifoaming agent supply section, the pressure of the foam layer can be adjusted to a predetermined range. Thereby, even if it is a case provided with a defoaming tank, the decomposition rate of sludge can be maintained in a predetermined range.

  The gas supply unit is composed of a porous material that mixes an ozone-containing gas containing ozone and oxygen and a gas that does not contain ozone, and a downstream side of the mixing unit, and supplies the gas to the liquid layer It is preferable to have a diffused gas. Thereby, the supply amount of ozone and the superficial velocity can be adjusted with a high degree of freedom. Therefore, even if the supply flow rate of the sludge-containing liquid or the properties of the sludge-containing liquid changes, the sludge decomposition rate and the separation accuracy between the sludge and its decomposition products and water can be maintained at a high level. Moreover, since fine bubble-like gas will be supplied from a diffused gas, the contact area of the gas in a liquid layer and a liquid can be enlarged. Furthermore, 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.

  In another aspect, the present invention provides a sludge treatment method for separating a sludge-containing liquid into a foam layer containing sludge decomposition products and a liquid layer containing water by treating the sludge-containing liquid with ozone in a reaction tank. Inside the liquid supply step of supplying the sludge-containing liquid, and the amount of ozone supplied to 1 g of suspended matter contained in the sludge of the sludge-containing liquid, the gas containing ozone in the liquid layer below the foam layer And a gas supply step of supplying the gas so that the superficial velocity of the gas is 0.0035 m / second or more.

  In the sludge treatment method described above, a sludge-containing liquid is supplied into the foam layer. 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. As described above, since the sludge-containing liquid and dissolved ozone can be efficiently contacted with each other 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 sufficiently decomposed.

  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.

  In the gas supply step, the ozone supply amount is 30 mg or more for the suspended matter 1 g contained in the sludge of the sludge-containing liquid, and the superficial velocity in the reaction tank is 0.0035 m / second or more. It is supplied to become. Thereby, while sludge is fully decomposed | disassembled and sludge is reduced, sludge and its decomposition product, and water can be isolate | separated with sufficient high precision.

  In the liquid supply step, the sludge-containing liquid is supplied at a position between 0.2H and 0.7H when the height of the entire inside of the reaction tank is H and the inner bottom of the reaction tank is used as a reference. preferable. As a result, the decomposition rate of sludge and the separation accuracy between sludge and its decomposition products and water can be achieved at a sufficiently high level.

  The sludge treatment method described above is based on the pressure measurement step for measuring the pressure of the foam layer, and the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, and the drainage from the reaction tank based on the pressure measured in the pressure measurement step. And an adjusting step for adjusting at least one of the discharge flow rates. The pressure in the foam layer depends on the supply pressure of the gas containing ozone in the gas supply process, the height of the foam layer, the liquid level height of the sludge-containing liquid, and the like. These values affect the reaction between ozone and sludge. Therefore, the pressure of the foam layer can be adjusted to a predetermined range by including an adjusting step for adjusting at least one of the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, and the discharge flow rate of the drain from the reaction tank. . This makes it possible to maintain the sludge decomposition rate within a predetermined range with high accuracy.

  The sludge treatment method described above includes a pressure measurement step for measuring the pressure of the foam layer, and a stirring step for breaking bubbles by stirring the foam discharged from the reaction vessel with a stirrer in the defoaming tank connected to the reaction vessel. An antifoaming agent supplying step for supplying an antifoaming agent to the antifoaming tank, and based on the pressure measured in the pressure measuring step, the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, You may have the adjustment process which adjusts at least 1 of the discharge flow rate of a drain, the rotation speed of a stirrer, and the supply flow rate of an antifoamer.

  In the case of providing a defoaming tank, the pressure in the foam layer is determined in addition to the supply pressure of the gas containing ozone from the gas supply unit, the height of the foam layer, and the liquid level height of the sludge-containing liquid. It depends on the separation rate of sludge and exhaust gas. Therefore, based on the pressure measured in the pressure measurement step, the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, the drain discharge flow rate from the reaction tank, the rotation speed of the stirrer, and the supply flow rate of the antifoaming agent By adjusting at least one, the pressure of the foam layer can be adjusted to a predetermined range. Thereby, even if it is a case provided with a defoaming tank, the decomposition rate of sludge can be maintained in a predetermined range with high accuracy.

  It is preferable to have a mixing step of mixing an ozone-containing gas containing ozone and oxygen and a gas not containing ozone before the gas supply step. Thereby, the supply amount of ozone and the superficial velocity can be adjusted with a high degree of freedom. Therefore, even if the supply flow rate of the sludge-containing liquid or the properties of the sludge-containing liquid changes, the sludge decomposition rate and the separation accuracy between the sludge and its decomposition products and water can be maintained at a high level.

  According to the present invention, in one aspect, there is provided an ozone treatment apparatus capable of sufficiently decomposing sludge to reduce the sludge and separating sludge and its decomposition products from water with high accuracy. be able to. Moreover, this invention provides the sludge processing method which can isolate | separate sludge and its decomposition product, and water with high precision while fully decomposing sludge and reducing sludge in another side surface. be able to.

FIG. 1 is a diagram illustrating an embodiment of an ozone treatment apparatus. FIG. 2 is a top view of the diffused gas attached to the tip of the gas supply unit. FIG. 3 is a diagram when the liquid supply unit is viewed from below. 4 (A) and 4 (B) are schematic views showing an enlarged cross section of the foam contained in the foam layer. FIG. 5 is a diagram illustrating an example of a control system that controls the pressure in the reaction vessel. FIG. 6 is a perspective view of a reaction vessel provided in another embodiment of the ozone treatment apparatus. It is a figure which shows an example of the sludge treatment system to which an ozone treatment apparatus is applied. It is the graph which plotted the data of the Example by making a horizontal axis an ozone basic unit and a vertical axis | shaft to the total VSS decomposition rate. It is the graph which plotted the data of the Example by making a horizontal axis a gas superficial velocity and a vertical axis | shaft with SS transfer rate. It is the graph which plotted the data of the Example by making a horizontal axis | shaft the value of calculation formula (I) and a vertical axis | shaft into SS transfer rate. It is the graph which plotted the data of the Example by making a horizontal axis | shaft the value of Formula (II) and a vertical axis | shaft into the total VSS decomposition rate. It is the graph which plotted the data of the Example by making a horizontal axis an ozone basic unit and a vertical axis | shaft to the total VSS decomposition rate.

  In the following, embodiments of the present invention will be described with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. In each drawing, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted in some cases.

  FIG. 1 is a diagram illustrating an embodiment of an ozone treatment apparatus. The ozone treatment apparatus 100 includes a reaction tank 10 and an antifoaming 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. The defoaming tank 30 is connected to an antifoaming agent supply unit 33 that supplies the defoaming agent to the defoaming tank 30. 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. The reaction tank 10 is provided with a pressure measurement unit 15 that measures the pressure of the foam layer 20. The contents of the ozone treatment apparatus 100 and the sludge treatment method using the ozone treatment apparatus 100 will be described below.

  The gas supply unit 50 supplies a gas containing ozone into the liquid layer 40 of the reaction vessel 10 (gas supply process). The gas supply unit 50 includes an ozone generation unit 56, an air supply unit 58, a mixing unit 55, a piping unit 54, and a diffused gas 52. As the ozone generator 56, a normal ozonizer or the like can be used. As the air supply unit 58, a normal air pump or the like can be used. The provision of the air supply unit 58 is not essential, and the air supply unit 58 may not be provided, or a supply unit that supplies an inert gas such as nitrogen may be provided instead of the air supply unit 58. .

  In the mixing unit 55, the gas 51 supplied to the inside of the liquid layer 40 is prepared by blending the ozone-containing gas generated in the ozone generation unit 56 and the air supplied from the air supply unit 58 (mixing step). ). By having such a mixing part 55, the gas superficial velocity of the reaction tank 10 and the ozone supply amount (ozone unit) to the reaction tank 10 can be individually adjusted. Therefore, even if the supply flow rate of the sludge-containing liquid or the properties of the sludge-containing liquid changes, the sludge decomposition rate and the separation accuracy between the sludge and its decomposition products and water can be maintained at a sufficiently high level. .

The gas 51 containing ozone prepared by the mixing unit 55 flows through the piping unit 54 and is supplied to the diffused gas 52 attached to the tip of the piping unit 54. The diffused gas 52 is made of a porous material such as ceramic. The decomposition product produced by decomposing sludge with ozone has viscosity. For this reason, bubbles 21 are formed on the liquid layer 40 by supplying the gas 51 from the gas supply unit 50. By supplying the gas 51 containing ozone from the diffused gas 52, the fine bubble-like gas 51 is supplied to the liquid layer 40. As a result, the contact area between the gas and the drain containing water in the liquid layer 40 can be increased. The concentration of ozone in the gas 51 from the gas supply unit 50 may be, for example, 20 to 150 mg-O ₃ / L or 50 to 120 mg-O ₃ / L.

  By supplying the gas 51 containing ozone to the liquid layer 40, ozone and the sludge contained in the liquid layer 40 can be made to react efficiently. If the gas bubbles supplied from the gas supply unit 50 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.

  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 vessel 10, the sludge can be sufficiently decomposed. As the sludge decomposition proceeds, the total VSS decomposition rate and TDS elution rate calculated by the following equations (1) and (3) increase. In this embodiment, the total VSS decomposition rate can be 20 wt% or more, preferably 25 wt% or more. In this embodiment, the TDS elution rate 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. When the separation accuracy between the sludge and its decomposition products and the drain containing water is improved, the SS transfer rate calculated by the following equation (2) increases. In this embodiment, the SS transfer rate can be 85% by weight or more, preferably 87% by weight or more.

Total VSS decomposition rate (% by weight) = [TDS ₁₆ + TDS ₁₈ −TDS ₁₂ ] × 100 / VSS ₁₂ (1)
SS transfer rate (% by weight) = [SS ₁₆ + TDS _16- TDS ₁₂ × flow rate of foam / flow rate of sludge containing liquid] × 100 / SS ₁₂ (2)
TDS dissolution rate (% by weight) = [TDS ₁₆ -TDS ₁₂ x foam flow rate / sludge containing liquid flow rate]] x 100 / VSS ₁₂ (3)

In the formulas (1), (2) and (3), TDS ₁₆ is the flow rate per unit time of TDS contained in the bubbles discharged from the upper part of the reaction tank 10, and TDS ₁₂ is supplied to the reaction tank 10. It is the flow rate per unit time of TDS contained in the sludge containing liquid. TDS ₁₈ is a flow rate per unit time of TDS contained in the drain discharged from the bottom of the reaction vessel 10. 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.

  From the viewpoint of sufficiently increasing the total VSS decomposition rate, the gas supply unit 50 preferably supplies a gas containing 30 mg or more of ozone to 1 g of suspended matter contained in the sludge of the sludge-containing liquid, and 40 mg or more of ozone. More preferably, a gas containing is supplied. From the viewpoint of reducing the sludge treatment cost, the gas supply unit 50 preferably supplies a gas containing 200 mg or less of ozone to 1 g of suspended matter contained in the sludge of the sludge containing liquid, and a gas containing 100 mg or less of ozone. Is more preferable, and it is more preferable to supply a gas containing 68 mg or less of ozone.

The amount of ozone contained in the gas supplied from the gas supply unit 50 with respect to 1 g of suspended solids contained in the sludge of the sludge-containing liquid is herein referred to as “ozone unit” (mg-O ₃ / g-SS). Called. From the viewpoint of achieving both an improvement in the total VSS decomposition rate and a reduction in sludge treatment cost, the ozone basic unit is preferably 30 to 200 mg-O ₃ / g-SS, more preferably 40 to 100 mg-O ₃ / g. a -SS, more preferably from _{40~68mg-O 3 / g-SS} .

  FIG. 2 is a view when the diffused gas 52 attached to the tip of the gas supply unit 50 is viewed from above, inside and outside the reaction vessel 10. Inside the reaction tank 10, the tip of the piping portion 54 is inserted so as to cross the central portion of the reaction tank 10. A plurality of diffused gases 52 having a substantially cylindrical shape and extending from the side portion of the piping portion 54 toward the side surface of the reaction tank 10 are provided side by side at predetermined intervals on both sides of the piping portion 54. Thus, by providing a plurality of the diffused gases 52 side by side, the gas containing ozone and the sludge contained in the liquid layer 40 can be sufficiently brought into contact with each other.

  The drainage of the liquid layer 40 increases in viscosity with the decomposition of the suspended matter (SS). For this reason, it is necessary to ensure the flowability in the reaction vessel 10. From the viewpoint of smooth circulation of the liquid layer 40 and sufficient contact between ozone and sludge contained in the liquid layer 40, the area ratio of the diffused gas 52 to the reaction tank 10 in the drawing viewed from above as shown in FIG. Is preferably 15 to 50%, more preferably 20 to 40%, and even more preferably 30 to 40%.

Returning to FIG. 1, the gas supply unit 50 supplies gas at a position lower than 0.2 H when the overall height of the reaction tank 10 is H and the inner bottom 10 a of the reaction tank 10 is used as a reference. . That is, the height _{h 0} of the upper end of the aeration gas 52 is lower than 0.2 H. In this way, by supplying the gas containing ozone from the gas supply unit 50 at a low position in the reaction tank 10, the height of the interface between the bubble layer 20 and the liquid layer 40 in the reaction tank 10 is sufficiently lowered. be able to. Therefore, the height of the foam layer 20 relative to the liquid layer 40 can be sufficiently increased in the reaction tank 10. From this point of view, the gas supply unit 50 is preferably configured to supply gas at a position lower than 0.15H when the inner bottom 10a is used as a reference, and a position lower than 0.1H. More preferably, the gas supply is configured to supply gas.

  The gas superficial velocity in the reaction vessel 10 is preferably 0.0035 m / second or more, more preferably 0.0037 m / second or more, from the viewpoint of sufficiently increasing the SS transfer rate. On the other hand, from the viewpoint of maintaining the total VSS decomposition rate sufficiently high, the gas superficial velocity is preferably 0.009 m / sec or less, more preferably 0.008 m / sec or less. In addition, the gas superficial velocity in this specification can be calculated | required by dividing the supply gas flow volume supplied from the gas supply part 50 by the cross-sectional area of the reaction tank 10. FIG. When the diameter of the reaction tank 10 varies along the height direction, the cross-sectional area can be obtained by dividing the internal volume of the reaction tank 10 by the height H of the entire inside of the reaction tank.

  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 decomposition and concentration of sludge does not proceed sufficiently in the foam layer 20, and the amount of water flowing out to the defoaming 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 part 12 supplies a sludge containing liquid into the inside of the foam layer 20 formed in the reaction tank 10 (liquid supply process). That is, the liquid supply part 12 should just be a structure which can supply a sludge containing liquid to the inside of the foam layer 20.

  FIG. 3 is a diagram of the liquid supply unit 12 when viewed from the bottom, inside and outside the reaction vessel 10. A branch pipe 12 </ b> A that is branched into a plurality of branches is provided at the tip of the liquid supply unit 12. The plurality of branch pipes 12A are parallel to each other, pass through one side surface of the reaction vessel 10, and extend toward the other side surface of the reaction vessel 10 so as to be aligned at a predetermined interval in the horizontal direction. Each of the branch pipes 12 </ b> A is arranged so as to substantially traverse the inside of the reaction vessel 10. The branch pipe 12A has a supply port 12a for supplying the sludge-containing liquid downward. As shown in FIG. 3, the liquid supply unit 12 has a plurality of sludge-containing liquid supply ports 12 a, thereby further improving the contact between the sludge contained in the sludge-containing liquid and the ozone contained in the bubbles 21. Can do.

  When the inside of the reaction vessel 10 is viewed from above or from below, the diffused gas 52 shown in FIG. 2 and the branch pipe 12A shown in FIG. 3 are arranged so that their extending directions (longitudinal directions) are parallel to each other. It is preferable. Thereby, the dispersion | variation in the decomposition | disassembly of the sludge by the position in the reaction tank 10 can fully be suppressed.

  The liquid supply part 12 is not limited to the shape of FIG. In some other embodiments, the liquid supply unit 12 is not branched and its tip is disposed at the center in the radial direction of the defoaming tank 30, and the sludge-containing liquid is discharged from an opening provided at the tip. Such a structure may be used.

The height _{h 2} of the liquid supply portion 12, the height of the entire interior of the reaction vessel 10 and H, the inner bottom 10a when a reference of the reactor 10, is within the range of 0.2H~0.7H It is preferable that it is in the range of 0.25H to 0.6H. That is, the height h ₃ from the liquid supply unit 12 to the upper end 10b of the reaction tank 10 is preferably in the range of 0.3H to 0.8H, and is in the range of 0.4H to 0.75H. Is preferred. Thereby, the total VSS decomposition rate and the SS transfer rate can be compatible at a sufficiently high level.

The height h ₁ of the interface between the foam layer 20 and the liquid layer 40 is 0.15H to 0.00 when the height of the entire inside of the reaction tank 10 is H and the inner bottom 10a of the reaction tank 10 is used as a reference. It is preferably within the range of 4H, more preferably within the range of 0.2H to 0.3H. By using such a height h ₁ , the dispersibility of the gas containing ozone in the liquid layer 40 is excellent while maintaining the sludge decomposition rate and the separation accuracy of the sludge and its decomposition products and water at a high level. Can be. Further, the sludge contained in the liquid layer 40 can be sufficiently decomposed.

The height h ₄ from the interface between the foam layer 20 and the liquid layer 40 to the lower end of the liquid supply unit 12 is in the range of 0.1H to 0.4H, where H is the overall height of the inside of the reaction tank 10. Is preferably within the range of 0.15 to 0.3H. Thereby, the total VSS decomposition rate and the SS transfer rate can be compatible at a sufficiently high level.

  FIG. 4 is a schematic diagram showing an enlarged cross section of the foam 21 included in the foam layer 20. As shown in FIGS. 4A and 4B, the foam 21 includes a foam main body 22, a sludge particle 24 attached to the periphery of the foam main body 22, and a decomposition product 26 generated by the decomposition of the sludge particle 24. And water 28 attached around the foam body 22. The foam body 22 is formed by surrounding the gas containing ozone supplied from the gas supply unit 50 to the liquid layer 40 with the liquid organic matter contained in the sludge and the 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. 4A shows the bubble 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 FIG. 4 (A) and FIG. 4 (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 defoaming tank 30 are connected by a pipe 16. The bubbles 21 are discharged from the reaction tank 10 through the pipe 16 connected to the upper part of the reaction tank 10 and introduced into the defoaming tank 30. The defoaming 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 defoaming tank 30, the stirrer 32 is operated and an antifoaming agent is supplied from the defoaming agent supply unit 33 to break the bubbles 21 to obtain a concentrate 29. By providing such a stirrer 32 and an antifoaming agent supply unit 33, 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). In addition, it is not essential to provide the stirrer 32 and the antifoamer supply part 33, and you may provide either one.

  A gas supply unit 34 that supplies a gas containing ozone is connected to the defoaming tank 30. Similarly to the gas supply unit 50, the gas supply unit 34 may have a diffused gas made of a porous material at the tip. The sludge particles 24 contained in the foam 21 can react with ozone by stirring the foam 21 with the stirrer 32 while supplying the gas containing ozone from the gas supply unit 34.

  By providing the defoaming tank 30, the ozone treatment device 100 can reduce the exclusive volume of the foam layer 20 in the reaction tank 10. Therefore, the reaction tank 10 can be downsized. In addition, the sludge treatment process can be shortened. However, providing the defoaming tank 30 is not essential.

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. By adjusting the discharge flow rate of the drainage from the pipe 18, it is possible to control the height h ₁ of the interface of the liquid layer 40 and foam layer 20 of the reaction vessel 10. 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 a decomposition product thereof in addition to water 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 flow rate 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 flow rate 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 flow rate 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 flow rate of the sludge-containing liquid may be provided based on the measurement result of the viscosity of the liquid layer 40. 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 on-line analyzer that measures the viscosity may be provided in the liquid layer 40 to automatically control the supply flow rate of the sludge-containing liquid. Alternatively, the liquid layer 40 may be appropriately sampled to measure the viscosity of the sample, and the supply flow rate of the sludge-containing liquid may be manually controlled based on the measurement result as necessary.

  FIG. 5 is a configuration diagram of a control system that controls the pressure in the reaction vessel 10. The pressure measurement unit 15 is installed at a height where the foam layer 20 is formed in the reaction vessel 10. Since the pressure measurement unit 15 has the detection unit inserted in the foam layer 20, the pressure measurement unit 15 can measure the pressure in the foam layer 20 (pressure measurement step). In the present embodiment, one pressure measurement unit 15 is provided in the reaction tank 10, but a plurality of pressure measurement units 15 may be provided. Thereby, the pressure in the different height of the foam layer 20 can be measured, and the state of the sludge decomposition process in the reaction tank 10 can be grasped in more detail.

  The pressure of the foam layer 20 measured by the pressure measuring unit 15 is not only the pressure of the gas supplied from the gas supply unit 50 but also the sludge particles 24 and the decomposition product 26 adhering to the foam 21 forming the foam layer 20. And the amount of water 28. When the amount of the sludge particles 24, the decomposition product 26, and the water 28 adhering to the foam 21 increases, the pressure of the foam layer 20 increases due to the gravity acting on them. The pressure of the foam layer 20 also depends on the number of foams 21 formed in the foam layer 20. As the number of bubbles 21 in the foam layer 20 increases, the amount of sludge particles 24, decomposed products 26, and water 28 adhering to the foam 21 also increases, and the pressure of the foam layer 20 also increases. The pressure of the foam layer 20 also depends on the bubble breaking speed of the foam 21 in the defoaming tank 30. When the bubble breaking speed of the foam 21 in the defoaming tank 30 is slowed down, the back pressure is applied to the reaction tank 10, so the pressure of the foam layer 20 generated in the reaction tank 10 increases.

The pressure P1 measured by the pressure measurement unit 15 is calculated by using the density ρ _{bubble of the} bubbles 21, the height h ₅ from the attachment position of the pressure measurement unit 15 to the upper surface of the pipe 16 and the internal pressure P2 of the defoaming tank 30. = Ρ _bubble × h ₅ + P2. Here, the internal pressure P2 of the defoaming tank 30 indicates a constant pressure when the bubble breaking is stably performed. Further, the density of the bubbles 21 depends on the amount of the sludge particles 24 attached to the bubbles. Accordingly, the amount of the sludge particles 24 attached to the bubbles 21 can be grasped based on the density ρ _{bubble of the} bubbles 21 calculated by the formula ρ _bubble = (P1−P2) / h ₅ . Therefore, if the pressure measured by the pressure measuring unit 15 is too low, the amount of the sludge particles 24 attached to the bubbles 21 decreases, and the total VSS decomposition rate and SS transfer rate tend to decrease.

This perspective density [rho _bubble foam 21 is preferably at 0.16 kg / ^{m 3} or more, more preferably 0.20 kg / ^{m 3} or more. Since the internal pressure P2 of the defoaming tank 30 varies depending on the equipment pressure loss at the subsequent stage of the defoaming tank 30 and the like, it is preferable to measure appropriately before the start of equipment operation. When the internal pressure P2 of the defoaming tank 30 exceeds a predetermined pressure, the defoaming tank is increased by increasing the rotational speed of the stirrer 32 or increasing the defoaming agent supply amount from the defoaming agent supply unit 33. 30 driving situations can be stabilized.

  If the pressure of the foam layer 20 is measured using the pressure measurement part 15 and the reaction tank 10 is controlled based on the measured value, the pressure fluctuation of the foam layer 20 can be suppressed and stable sludge treatment can be performed. As shown in FIG. 5, the measurement of the pressure measured by the pressure measurement unit 15 is sent to the control unit 90 via the signal line 92. The control unit 90 adjusts each adjustment unit according to the input pressure measurement value. The control unit 90 may be configured to compare the target range of pressure and the measured value to determine whether or not pressure adjustment is necessary. A gas flow rate adjusting unit 50A for adjusting the flow rate of the gas containing ozone in the gas supply unit 50, a flow rate adjusting unit 12B for adjusting the supply flow rate of the sludge-containing liquid in the liquid supply unit 12, and a discharge flow rate of drain discharged from the reaction tank 10. A drain discharge flow rate adjusting unit 18A for adjusting the rotation speed, a rotation speed adjusting unit 32A for adjusting the rotation speed of the agitator 32 for breaking the bubbles 21 in the defoaming tank 30, and an antifoaming agent for adjusting the injection amount of the defoaming agent Signal lines 94A, 94B, 94C, 94D, and 94E are connected so that signals can be transmitted to and received from the flow rate adjusting unit 33A. Through these signal lines, the control unit 90 receives values of the flow rate of the gas containing ozone, the drain discharge rate, the rotation speed of the stirrer 32, and the supply flow rate of the antifoaming agent from each adjustment unit. You may be comprised so that.

  When the control unit 90 determines that the pressure of the foam layer 20 in the reaction tank 10 needs to be adjusted, the gas flow rate adjustment unit 50A, the flow rate adjustment unit 12B, the drain discharge flow rate adjustment unit 18A, the rotation speed adjustment unit 32A, and The control unit 90 transmits a control signal to at least one adjustment unit of the defoamer flow rate adjustment unit 33A. For example, the control unit 90 selects the adjustment unit having the largest difference between the target setting value and the measurement value in each adjustment unit, and transmits the control signal. The control method is not limited to such an embodiment.

The control unit that has received the control signal has at least one operating condition selected from the flow rate of the gas containing ozone, the supply flow rate of the sludge-containing liquid, the drain discharge flow rate, the rotational speed of the stirrer 32, and the injection amount of the antifoaming agent. Is adjusted (adjustment step). By adjusting the operating conditions, the pressure of the foam layer 20 is adjusted. Thereby, the pressure of the foam layer 20 is adjusted to a predetermined range. By adjusting the pressure to a predetermined range, the rising speed of the foam 21 in the foam layer 20, the height h ₁ of the interface between the foam layer 20 and the liquid layer 40, the flow rate of the drain discharged from the pipe 18 and the like are stabilized. Can be maintained. As a result, it is possible to estimate the amount of the sludge particles 24 adhering to the bubbles 21 and to stably decompose the sludge particles 24 into the decomposition products 26 in the reaction tank 10 within a predetermined range. . It is not essential to provide such a control unit 90 and each adjustment unit.

  FIG. 6 is a perspective view of a reaction tank 10A provided in an ozone treatment apparatus according to another embodiment. The inside of the reaction tank 10 </ b> A is partitioned into a plurality of rooms by a partition plate 14. Thus, even if the reaction tank 10A is scaled up by dividing the inside of the reaction tank 10A into a plurality of rooms, the formation of the foam layer 20 proceeds smoothly, and the sludge is decomposed and sludge. In addition, the separation accuracy between the decomposition product and water can be achieved at a high level. In the case of 10 A of reaction tanks, the liquid supply part 12 supplies a sludge containing liquid to the foam layer 20 in each room, and the gas supply part 50 supplies the gas containing ozone to the liquid layer 40 in each room. The partition plate 14 may have an opening that allows the drain of the liquid layer 40 and / or the foam 21 of the foam layer 20 to flow between adjacent rooms. In order to enable such distribution, the partition plate 14 may have a mesh shape, for example.

  FIG. 7 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 80 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 80 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 80. In addition, the use of the ozone treatment apparatus 100 is not limited to the sludge treatment system 1 of FIG. 6, It can apply to the various systems which process a sludge containing liquid.

  The sludge treatment method of the present embodiment is a sludge treatment method in which a sludge-containing liquid is treated with ozone in a reaction tank 10 to separate the foam layer 20 containing a sludge decomposition product and the liquid layer 40 containing water, A mixing step of mixing an ozone-containing gas containing ozone and oxygen and a gas not containing ozone, a liquid supply step of supplying a sludge-containing liquid into the foam layer 20, and a liquid layer below the foam layer 20 In 40, gas containing ozone is supplied so that the amount of ozone supplied to 1 g of suspended matter contained in the sludge of the sludge-containing liquid is 30 mg or more and the superficial velocity of the gas is 0.0035 m / second or more. And a gas supply step. Each step can be performed based on the description of the ozone treatment apparatus 100 described above. Another arbitrary step may be performed before, after, or simultaneously with each step.

  For example, using a control system as shown in FIG. 5, the foam discharged from the reaction tank 10 is agitated in the pressure measurement step for measuring the pressure of the foam layer 20 and the defoaming tank 30 connected to the reaction tank 10. You may have the stirring process which stirs with a container and breaks bubbles, and the antifoamer supply process which supplies an antifoamer to the antifoaming tank 30 from the antifoamer supply part 33. In this case, based on the pressure measured in the pressure measurement step, the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, the drain discharge flow rate from the reaction tank 10, the rotation speed of the stirrer 32, and the antifoaming agent It is preferable to have an adjustment step of adjusting at least one of the supply flow rates. This makes it possible to adjust the pressure of the foam layer to a predetermined range and maintain the sludge decomposition rate within a predetermined range with high accuracy.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment at all. For example, it is not essential for the ozone treatment apparatus of the present invention to include a mixing unit that mixes an ozone-containing gas and a gas not containing ozone. In addition, the sludge treatment method of the present invention does not necessarily include a mixing step, and ozone-containing gas that has not undergone the mixing step may be supplied into the liquid layer 40 in the gas supply step.

  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
Ozone treatment was performed by supplying the sludge-containing liquid generated from the sewage water treatment device to the ozone treatment device as shown in FIG. The specification of the reaction vessel 10 was as follows.
<Specifications of reaction vessel 10>
-Overall height H of the reaction tank 10: 2.2 m
-Height h ₀ of the gas supply unit 50 (the upper end height of the diffused gas 52): 0.19 m
-Area ratio of the diffused gas 52 with respect to the reaction tank 10 when viewed from above as shown in FIG. 2: 36%

The sludge-containing liquid was supplied into the foam layer 20. From the gas supply unit 50, a mixed gas of oxygen gas containing ozone and air was supplied to the reaction vessel 10. 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. By adjusting the drain discharge flow rate, the height h ₁ of the interface between the liquid layer 40 and the foam layer 20 with respect to the inner bottom 10a of the reaction vessel 10 was adjusted. Heights h ₂ to h ₄ shown in FIG. 1 were as shown in Table 1.

  The height of the interface between the liquid layer 40 and the foam layer 20 was controlled by adjusting the drain discharge flow rate from the bottom of the reaction vessel 10. During the sludge treatment, the sludge-containing liquid supplied to the reaction tank 10, the drain discharged from the bottom of the reaction tank 10, and the bubbles discharged from the top of the reaction tank 10 were sampled.

The concentration of suspended solids (SS) contained in the sampled sludge-containing liquid was measured, and the supply amount of suspended solids per unit time was determined from the measured concentration and the supply flow rate of the sludge-containing liquid. Then, the ratio of the amount of ozone supply (mg) to the amount of supply of suspended matter (SS), that is, the ozone unit [mg-O ₃ / g-SS] was determined. Moreover, the density | concentration of the evaporation residue (TDS) contained in sludge containing liquid was measured.

  The concentration of sampled drain evaporation residue (TDS) and the sampled foam suspension (SS), evaporation residue (TDS) and volatile organic (VSS) concentrations were measured. From these measured values, the total VSS decomposition rate and SS transport rate were calculated by the above formulas (1) and (2).

  After changing the ozone basic unit, gas superficial velocity and supply flow rate of sludge containing liquid, sludge treatment, the operation is stabilized, the same sampling is performed, and the ozone basic unit, SS transfer rate and total VSS decomposition rate are calculated. Calculated. These calculation results and sludge treatment conditions are shown in Table 1, Table 2, and Table 3.

  In any of the operating conditions of Examples 1-1 to 1-14 shown in Tables 1 to 3, the total VSS decomposition rate was 20% by weight or more, and the SS transfer rate was 60% by weight or more. Thus, in Examples 1-1 to 1-14, it was possible to separate sludge and its decomposition products from the sludge-containing liquid with high accuracy while sufficiently decomposing the sludge contained in the sludge-containing liquid.

  FIG. 8 is an example in which the supply flow rate of the sludge-containing liquid is the same among Examples 1-1 to 1-14 shown in Tables 1 to 3 and the concentration of suspended solids in the sludge-containing liquid is the same. It is the graph which plotted the data of 1-1 to 1-4. In FIG. 8, the white circle data is data of Example 1-4 in which the sludge treatment was performed in the summer, and the black circle data is data in which the sludge treatment was performed in the winter. Although there was a change due to climate, a good correlation was observed between ozone intensity and total VSS decomposition rate. From this result, it was confirmed that the total VSS decomposition rate can be increased by increasing the ozone basic unit. From the results shown in FIG. 8, it can be seen that the total VSS decomposition rate can be increased to 20 wt% or more by supplying 30 mg or more of ozone to 1 g of suspended matter (SS).

  FIG. 9 shows Examples 1-1 to 1-14 in which the gas superficial velocity was changed in order to investigate the influence of the gas superficial velocity among Examples 1-1 to 1-14 shown in Tables 1 to 3. Is a graph plotting the data (other conditions were almost constant). A good correlation was observed between the gas superficial velocity and the SS transfer rate. It was confirmed that the SS transfer rate can be increased by increasing the gas superficial velocity. From the results shown in FIG. 9, it can be seen that the SS transfer rate can be increased to 80% by weight or more by setting the gas superficial velocity to 0.035 m / second or more.

From the comparison between Example 1-7 and Example 1-8 in which the supply flow rate of sludge-containing liquid, the ozone basic unit, and the gas superficial velocity are almost the same, if h ₄ is increased and h ₁ is decreased, It was confirmed that the VSS decomposition rate was lowered and the SS transfer rate could be increased. Thus, by changing the height h ₁ of the interface between the foam layer 20 and the liquid layer 40, the values of the total VSS decomposition rate and the SS transfer rate can be adjusted.

(Example 2)
Using a reaction tank having a different size from that of Example 1, a sludge-containing liquid generated from a sewage water treatment apparatus was supplied, and ozone treatment was performed under the following conditions.
<Conditions for ozone treatment>
-Overall height H of the reaction vessel 10: 3.44 m
-Height h ₀ of the gas supply unit 50 (the upper end height of the diffused gas 52): 0.15 m
-Height h ₁ of the liquid layer 40: 0.69 m
-Height h ₂ of liquid supply unit 12: 1.9 m

  As shown in Table 4, Table 5, and Table 6, sludge treatment was performed under different conditions. And like Example 2, the total VSS decomposition rate and SS transfer rate in each condition were computed. Moreover, the value of the following formula (I) and formula (II) was computed on each condition. These results are shown in Tables 4, 5 and 6. In addition, the discharge | emission flow volume of a foam in Table 4, Table 5, and Table 6, and Formula (II) is a flow volume when the foam which flows out from the upper part of the reaction tank 10 is converted into a liquid.

Supply flow rate of sludge-containing liquid per reaction tank cross-sectional area (L / m ² / min) x SS concentration (wt%) in sludge-containing liquid / 100 / gas superficial velocity (m / sec) / h ₄ (m )… (I)
Basic ozone unit (mg-O ₃ / g-SS) x [(h ₃ + h ₄ ) (m) / gas vacancy speed (m / sec)] x [(h ₃ + h ₄ ) (m) / reactor unit Discharge flow rate of bubbles per cross-sectional area (L / m ² / min)]… (II)

  In any of the operating conditions of Examples 2-1 to 2-14 shown in Tables 4 to 6, the total VSS decomposition rate was 20% by weight or more, and the SS transfer rate was 60% by weight or more. Thus, in Examples 2-1 to 2-14, it was possible to efficiently separate the sludge and its decomposition products from the sludge-containing liquid while sufficiently decomposing the sludge contained in the sludge-containing liquid.

  FIG. 10 is a graph in which the data of Examples 2-1 to 2-14 are plotted with the horizontal axis representing the value of the calculation formula (I) and the vertical axis representing the SS transfer rate. The symbols of the points plotted in FIG. 10 correspond to “identification numbers in the figure” in Tables 4, 5, and 6. It was confirmed that there is a good correlation between the calculation formula (I) and the SS transfer rate. The denominator of the calculation formula (I) includes the gas superficial velocity. Therefore, it was confirmed that if the gas superficial velocity is increased, the SS transfer rate tends to increase.

  In FIG. 10, the points (1), (2), and (7) are the results when the supply flow rate of the sludge-containing liquid is about 7500 L / min. Points (3) and (4) are the results when the supply flow rate of the sludge-containing liquid is about 6000 L / min. The point (5) is the result when the supply flow rate of the sludge-containing liquid is about 4500 L / min. The point (6) is the result when the supply flow rate of the sludge-containing liquid is about 4100 L / min. From these results, it was confirmed that the SS transfer rate can be increased by reducing the value of the formula (I) regardless of the supply flow rate of the sludge-containing liquid.

  FIG. 11 is a graph in which the data of Examples 2-1 to 2-14 are plotted with the horizontal axis as the value of the following calculation formula (II) and the vertical axis as the total VSS decomposition rate. From these results, it was confirmed that the total VSS decomposition rate tends to increase by increasing the calculation formula (II). In the calculation formula (II), the gas superficial velocity is included in the denominator, and the ozone unit is included in the numerator. From this, it can be seen that the total VSS decomposition rate tends to increase as the ozone unit increases, but the total VSS decomposition rate tends to decrease as the gas superficial velocity increases.

  FIG. 12 is a graph in which the data of Examples 2-1 to 2-14 are plotted with the horizontal axis representing the ozone basic unit and the vertical axis representing the total VSS decomposition rate. From these results, it can be seen that the total VSS decomposition rate tends to increase as the ozone unit increases.

  From the results of FIGS. 10, 11 and 12, in order to make both the SS transfer rate and the total VSS decomposition rate higher than a predetermined target value, for example, first, based on FIG. Accordingly, the lower limit of the gas superficial velocity for satisfying the target value of the SS transfer rate is set. Thereafter, the gas superficial velocity and the ozone intensity are set so as to satisfy the target value of the total VSS decomposition rate within a range that satisfies the lower limit, based on FIGS. 11 and 12. Accordingly, both the SS transfer rate and the total VSS decomposition rate can be made higher than a predetermined target value in the sludge treatment.

  DESCRIPTION OF SYMBOLS 1 ... Sludge processing system 10, 10A ... Reaction tank, 10a ... Inner bottom, 10b ... Upper end, 12 ... Liquid supply part, 12A ... Branch pipe, 12B ... Flow control part, 12a ... Supply port, 14 ... Partition plate, 15 ... pressure measuring unit, 16, 18 ... piping, 18A ... drain discharge flow rate adjusting unit, 20 ... foam layer, 21 ... foam, 22 ... foam body, 24 ... sludge particles, 26 ... decomposed product, 28 ... water, 29 ... concentration 30 ... Defoaming tank, 32 ... Stirrer, 32A ... Rotational speed adjustment unit, 33 ... Defoaming agent supply unit, 33A ... Defoaming agent flow rate adjustment unit, 34 ... Gas supply unit, 40 ... Liquid layer, 50 ... Gas supply part, 50A ... Gas flow rate adjustment part, 51 ... Gas, 52 ... Sparging gas, 54 ... Pipe part, 55 ... Mixing part, 56 ... Ozone generation part, 58 ... Air supply part, 60 ... Sludge treatment apparatus, 70 ... Digestion fermentation apparatus, 80 ... water treatment apparatus, 90 ... control unit, 92, 94A, 94B, 9 C, 94D, 94E ... signal line, 100 ... ozone treatment apparatus.

Claims (10)

An ozone treatment apparatus comprising a reaction tank that treats sludge-containing liquid with ozone and separates it into a foam layer containing a sludge decomposition product and a liquid layer containing water,
A liquid supply unit for supplying the sludge-containing liquid into the foam layer;
A gas supply part for supplying a gas containing ozone to the inside of the liquid layer below the foam layer,
The gas supply unit is configured so that the supply amount of ozone to 1 g of suspended matter contained in the sludge of the sludge-containing liquid is 30 mg or more, and the gas superficial velocity of the reaction tank is 0.0035 m / second or more. An ozone treatment device that supplies gas.   The liquid supply unit supplies the sludge-containing liquid at a position between 0.2H and 0.7H when the height of the entire inside of the reaction tank is H and the inner bottom of the reaction tank is used as a reference. The ozone treatment apparatus according to claim 1. A pressure measuring unit for measuring the pressure of the foam layer;
Based on the pressure measured by the pressure measurement unit, the supply flow rate of the sludge-containing liquid supplied from the liquid supply unit, the supply flow rate of the gas from the gas supply unit, and the discharge of drain from the reaction tank The ozone processing apparatus of Claim 1 or 2 provided with the control part which adjusts at least 1 of a flow volume. A pressure measuring unit for measuring the pressure of the foam layer;
A defoaming tank connected to the reaction tank and stirring the foam discharged from the reaction tank with a stirrer to break up bubbles;
An antifoam supply part for supplying an antifoam to the defoaming tank,
Based on the pressure measured by the pressure measurement unit, the supply flow rate of the sludge-containing liquid supplied from the liquid supply unit, the supply flow rate of the gas from the gas supply unit, and the discharge flow rate of drain from the reaction tank And a controller that adjusts at least one of the rotation speed of the stirrer and the supply flow rate of the antifoaming agent from the antifoaming agent supply unit. . The gas supply unit
A mixing section for mixing an ozone-containing gas containing ozone and oxygen and a gas not containing ozone;
The ozone treatment apparatus according to any one of claims 1 to 4, further comprising a diffused gas that is made of a porous material and supplies the gas to the liquid layer on the downstream side of the mixing unit. In a reaction tank, a sludge treatment method for treating a sludge-containing liquid with ozone to separate into a foam layer containing a sludge decomposition product and a liquid layer containing water,
A liquid supply step for supplying the sludge-containing liquid into the foam layer;
In the liquid layer below the foam layer, ozone-containing gas is supplied in an amount of 30 mg or more of ozone to 1 g of suspended matter contained in the sludge of the sludge-containing liquid, and the superficial velocity of the gas A sludge treatment method comprising: a gas supply step of supplying the gas so as to be 0.0035 m / second or more.   In the liquid supply step, the sludge-containing liquid is supplied at a position between 0.2H and 0.7H, where H is the total height of the inside of the reaction tank and the inner bottom of the reaction tank is used as a reference. The sludge treatment method according to claim 6. A pressure measuring step for measuring the pressure of the foam layer;
An adjustment step of adjusting at least one of the supply flow rate of the sludge-containing liquid, the supply flow rate of the gas, and the discharge flow rate of the drain from the reaction tank based on the pressure measured in the pressure measurement step. The sludge treatment method according to claim 6 or 7. A pressure measuring step for measuring the pressure of the foam layer;
In the defoaming tank connected to the reaction tank, a stirring step of stirring the foam discharged from the reaction tank with a stirrer and breaking the foam,
An antifoaming agent supplying step of supplying an antifoaming agent to the antifoaming tank;
Based on the pressure measured in the pressure measurement step, the sludge-containing liquid supply flow rate, the gas supply flow rate, the drain discharge flow rate from the reaction tank, the rotation speed of the stirrer, and the antifoaming agent The sludge treatment method according to claim 7 or 8, further comprising an adjustment step of adjusting at least one of the supply flow rates.   The sludge treatment method according to any one of claims 6 to 9, further comprising a mixing step of mixing the ozone-containing gas containing ozone and oxygen and a gas not containing ozone before the gas supply step.

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