Wastewater treatment device and method for starting or restarting the device

Abstract

The present invention provides a novel wastewater treatment device and a method for starting or restarting the treatment device, which can maintain excellent wastewater treatment capacity. [Solution] The processing apparatus 10 includes a packed tower 20 having a catalyst layer 22 filled with a solid catalyst 21, a discharge pipe 30 connected to a position above the catalyst layer, and a liquid supply unit 40 capable of supplying liquid to a position below the catalyst layer. The liquid supply unit can supply either a first liquid 41 or a second liquid 42 whose COD(Cr) is greater than that of the first liquid.

Description

Technical Field

[0001] The present invention relates to a wastewater treatment apparatus and a method for starting or restarting the apparatus.

Background Art

[0002] Wastewater discharged from various industrial plants such as chemical plants, food processing equipment, metal processing equipment, metal plating equipment, printing plate making equipment, and photographic processing equipment is purified by various methods including wet oxidation (treatment), wet decomposition, ozone oxidation, and hydrogen peroxide oxidation.

[0003] As a wastewater treatment apparatus, for example, an apparatus based on a wet oxidation treatment method using a reaction tower (packed tower) filled with a solid catalyst, as described in Patent Document 1, is known. Here, the wet oxidation treatment method is a treatment method that decomposes organic matter in liquid using oxygen or an oxidizing agent under high temperature and high pressure conditions, and a solid catalyst is used to improve treatment efficiency.

[0004] Incidentally, in the case of a wastewater treatment apparatus using a solid catalyst, it is known that the wastewater treatment capacity decreases when the apparatus continues to operate, and the main cause of this is considered to be deterioration of the solid catalyst. There are various factors that cause deterioration of the solid catalyst; for example, organic components contained in wastewater or substances generated by conversion in the reactor may adhere to the surface of the solid catalyst. In response to this, Patent Document 1 prevents organic components from adhering to the solid catalyst by separating adherent organic components in advance through membrane filtration.

[0005] Other deterioration factors include that the action of wastewater and oxygen-containing gas introduced into the reaction tower causes movement, vibration and other motions of the solid catalyst in the catalyst layer, leading to wear, collapse or other damage to the solid catalyst. In response to this, Patent Document 2 physically presses the solid catalyst by a pressing means such as a grid or a wire mesh to suppress the movement of the solid catalyst, thereby preventing deterioration of the solid catalyst due to wear, collapse or other damage, and preventing a decrease in the treatment performance of the solid catalyst.

[0006] Furthermore, it is known that the state of the solid catalyst can change due to movement or other factors depending on how the wastewater treatment device is used, similar to the above, and that the treatment performance of the solid catalyst can decrease. As shown in Patent Document 2, the decrease in the treatment performance of the solid catalyst can be prevented by physically pressing down on the solid catalyst. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-266087 [Patent Document 2] Patent No. 5330751 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, while methods such as those described in Patent Documents 1 and 2 can suppress to some extent the decline in processing performance caused by the adhesion of organic components to the solid catalyst and the movement of the solid catalyst, there is a need for devices that can more effectively prevent the decline in processing performance. Furthermore, methods such as those described in Patent Document 2 have the problem of not being able to prevent the decline in processing performance caused by factors other than the movement of the solid catalyst.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a novel wastewater treatment device and a method for starting or restarting the treatment device that can maintain the wastewater treatment capacity. [Means for solving the problem]

[0010] The inventors of the present invention conducted diligent research to solve the above problems. As a result, they discovered that the above objectives can be achieved by a processing apparatus having a predetermined discharge pipe and liquid supply unit, and by a starting method and restarting method for a processing apparatus having a step of supplying a predetermined liquid, and thus completed the present invention.

[0011] The above objective can be achieved by the present invention having the following configuration, and the present invention encompasses the following aspects and forms.

[0012] One aspect of the present invention is, 1. A packed tower having a catalyst layer filled with a solid catalyst, A discharge pipe connected to a position above the catalyst layer, The apparatus includes a liquid supply unit located below the catalyst layer, which is capable of supplying either a first liquid or a second liquid having a COD(Cr) greater than the COD(Cr) of the first liquid.

[0013] 2. In the processing apparatus described in 1. above, The packed column further includes a booster gas supply unit that supplies booster gas to the packed column to increase the internal pressure of the packed column. Preferably, the pressurizing gas supply unit supplies the pressurizing gas to a position above the catalyst layer via the discharge pipe.

[0014] 3. In the processing apparatus described in 2. above, A gas supply unit that supplies oxygen-containing gas to a position below the catalyst layer, Preferably, the gas supply unit further includes a switching unit that can switch between supplying the pressurized gas to a position above the catalyst layer and supplying the oxygen-containing gas to a position below the catalyst layer.

[0015] 4. In the processing apparatus described in 3. above, it is preferable that the liquid supply unit supplies either the first liquid or the second liquid when the oxygen-containing gas is supplied by the gas supply unit.

[0016] 5. In the processing apparatus described in 3. above, it is preferable that the pressurizing gas supply unit supplies the same oxygen-containing gas as the pressurizing gas supplied by the gas supply unit to the packed tower.

[0017] 6. The treatment apparatus according to any one of 1. to 5. above, preferably further comprising a heater for heating the packed column.

[0018] 7. The treatment apparatus according to any one of 1. to 6. above, wherein the first liquid is preferably ion-exchanged water, pure water, ultrapure water, industrial water, well water, or tap water.

[0019] 8. The treatment apparatus according to any one of 1. to 7. above, wherein the solid catalyst preferably contains at least one selected from the group consisting of one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof, and activated carbon.

[0020] 9. The treatment apparatus according to any one of 1. to 8. above is preferably used for wet oxidation treatment.

[0021] Another aspect of the present invention is 10. A method for starting or restarting a treatment apparatus comprising a packed column having a catalyst layer filled with a solid catalyst, the method comprising: a first water passing step of supplying a first liquid to a position below the catalyst layer and passing the first liquid through a discharge pipe connected to a position above the catalyst layer; after the first water passing step, a second water passing step of supplying a second liquid having a COD(Cr) higher than that of the first liquid to a position below the catalyst layer, which is a method for starting or restarting the treatment apparatus.

[0022] 11. In the method for starting or restarting the treatment apparatus according to 10. above, the method preferably comprises a pressure raising step that is performed prior to the first water passing step, wherein a pressure raising gas is supplied to a position above the catalyst layer via the discharge pipe to raise the internal pressure of the packed column.

[0023] 12. In the method for starting or restarting the treatment apparatus according to 11. above,

[0001] 5>In the pressurization step, it is preferable to switch to supplying oxygen-containing gas to a position below the catalyst layer after the internal pressure of the packed column reaches a set pressure (P) by supplying the pressurizing gas to a position above the catalyst layer.

[0024] 13. In the starting or restarting method of the processing device described in 12. above, In the first water supply step, the first liquid is supplied while the oxygen-containing gas is supplied to a position below the catalyst layer. In the second water supply step, it is preferable to supply the second liquid while the oxygen-containing gas is supplied to a position below the catalyst layer.

[0025] 14. In the starting or restarting method of the processing device described in 12. or 13. above, In the pressurization step, it is preferable to supply the same oxygen-containing gas as the oxygen-containing gas to the packed tower as the pressurizing gas.

[0026] 15. In the starting or restarting method of the processing apparatus described in any of items 10 to 14 above, it is preferable to further include a heating step of heating the packed tower after the first water flow step and before the second water flow step, while the first liquid has been passed through the discharge pipe.

[0027] 16. In the starting or restarting method of the processing apparatus described in any of items 10 to 15 above, it is preferable that the first liquid is deionized water, pure water, ultrapure water, industrial water, well water, or tap water.

[0028] 17. In the starting or restarting method of the processing apparatus described in any of items 10 to 16 above, it is preferable that the solid catalyst includes one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof, and at least one selected from the group consisting of activated carbon.

[0029] 18. The starting or restarting method of the processing apparatus described in any of items 10 to 17 above is preferably used for wet oxidation treatment. [Effects of the Invention]

[0030] According to the present invention, it is possible to provide a novel wastewater treatment device that can maintain the wastewater treatment capacity, and a method for starting or restarting the treatment device. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram showing the processing apparatus of an embodiment. [Figure 2] This is a schematic diagram showing the packed column in Figure 1. [Modes for carrying out the invention]

[0032] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiments shown herein are illustrative examples to embody the technical idea of ​​the present invention and do not limit the present invention. Therefore, all other implementable forms, examples (test examples), and operational techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included in the scope and spirit of the present invention, as well as in the claims and their equivalents.

[0033] Furthermore, the drawings attached to this specification may be schematically represented with changes to scale, aspect ratio, shape, etc., from the actual object for the sake of illustration and ease of understanding, but these are merely examples and do not limit the interpretation of the present invention.

[0034] In this specification, ordinal numbers such as "the first," "the second," etc., may be used. However, unless otherwise specified, these ordinal numbers are used for the purpose of identifying the constituent elements for the sake of explanation, and do not specify a number or order.

[0035] <Embodiment> As shown in Figures 1 and 2, the apparatus 10 of the embodiment generally comprises a packed tower 20 having a catalyst layer 22 filled with a solid catalyst 21, a discharge pipe 30 connected to a position above the catalyst layer 22, and a liquid supply unit 40 located below the catalyst layer 22 that can supply either the first liquid 41 or the second liquid 42. The second liquid 42 is the liquid to be treated. The COD(Cr) of the second liquid 42 is greater than that of the first liquid 41.

[0036] The processing apparatus 10 further includes a booster gas supply unit 50 that supplies booster gas to the packed column 20 to increase the internal pressure of the packed column 20. The booster gas supply unit 50 supplies the booster gas to a position above the catalyst layer 22 via a discharge pipe 30.

[0037] The processing apparatus 10 further includes a gas supply unit 60 that supplies oxygen-containing gas to a position below the catalyst layer 22, and a switching unit 70. The switching unit 70 can switch between supplying pressurized gas to a position above the catalyst layer 22 by the pressurized gas supply unit 50 and supplying oxygen-containing gas to a position below the catalyst layer 22 by the gas supply unit 60.

[0038] The processing unit 10 will be described in detail below.

[0039] The processing apparatus 10 of this embodiment is suitably used for wet oxidation treatment.

[0040] The first liquid 41 is any liquid whose COD(Cr) is less than that of the second liquid 42. Specifically, the first liquid 41 can be exemplified by deionized water, pure water, ultrapure water, industrial water, well water, or tap water.

[0041] The first liquid 41 may be a liquid that does not contain the second liquid 42 to be treated, or a liquid that contains the second liquid 42 to be treated. In other words, the first liquid 41 may be a diluted liquid of the second liquid 42. For convenience, in the following explanation, the second liquid 42 to be treated may be referred to as "wastewater," and the first liquid 41 may be referred to as "non-wastewater."

[0042] The liquid supply unit 40 can supply either the first liquid 41 or the second liquid 42. Therefore, when starting or restarting the processing device 10, for example, an operating mode can be realized in which non-wastewater (first liquid 41) is first circulated through the catalyst layer 22 of the packed column 20, and then wastewater (second liquid 42) is circulated through it.

[0043] The packed tower 20 has packing layers 23 and 24 provided below and above the catalyst layer 22, respectively (see Figure 2). Packing layers 23 and 24 have the function of holding the catalyst layer 22. Packing layers 23 and 24 are filled with, for example, SUS balls.

[0044] The packed column 20 has a supply pipe 43 connected below the catalyst layer 22. The supply pipe 43 is connected to a first pipe 44 for introducing a first liquid 41 and a second pipe 45 for introducing a second liquid 42. The first pipe 44 is provided with a first on-off valve 46, and the second pipe 45 is provided with a second on-off valve 47. The supply pipe 43 is provided with a pump 48 for pressurizing the first liquid 41 or the second liquid 42, a first heater 49 consisting of a heat exchanger, and a temperature controller PT for detecting the temperature of the fluid (liquid and / or gas) supplied to the packed column 20. The fluid (liquid and / or gas) supplied to the packed column 20 is heated to a predetermined temperature by the first heater 49.

[0045] The discharge piping 30 includes a cooler 31, which is composed of a heat exchanger, and a gas-liquid separator 32. The fluid (liquid and / or gas) discharged from the packed tower 20 is cooled to a predetermined temperature by the cooler 31. The gas-liquid separator 32 includes a third pipe 33 connected to the region where the separated gas is located, a fourth pipe 34 connected to the region where the separated liquid is located, a pressure controller PC for detecting the pressure of the separated gas, and a liquid level controller LC for detecting the liquid level of the separated liquid. The third pipe 33 is equipped with a pressure control valve 35 for adjusting the gas pressure in the gas-liquid separator 32. The fourth pipe 34 is equipped with a liquid level control valve 36 for adjusting the liquid level in the gas-liquid separator 32. The gas separated in the gas-liquid separator 32 is discharged via the third pipe 33 toward equipment not shown. The liquid separated in the gas-liquid separator 32 is discharged via the fourth pipe 34 toward equipment not shown.

[0046] The processing apparatus 10 includes a compressor 61 for compressing an oxygen-containing gas (e.g., air), a fifth pipe 62 for introducing the oxygen-containing gas into the compressor 61, a sixth pipe 63 for introducing the compressed oxygen-containing gas into a supply pipe 43, and a seventh pipe 51 for introducing the compressed oxygen-containing gas into a third pipe 33 of the gas-liquid separator 32. The sixth pipe 63 is connected to the supply pipe 43 between the pump 48 and the first heater 49. The seventh pipe 51 is connected to the third pipe 33 between the gas-liquid separator 32 and the pressure control valve 35. The sixth pipe 63 is equipped with a flow control valve 64 and a shut-off valve 65. The shut-off valve 65 is located downstream of the flow control valve 64. The seventh pipe 51 is equipped with an on / off valve 52. When the shut-off valve 65 is open and the on-off valve 52 is closed, the compressed oxygen-containing gas is flowed through the sixth pipe 63 and the supply pipe 43, with its flow rate controlled by the flow control valve 64, and supplied to a position below the catalyst layer 22 of the packed tower 20. When the shut-off valve 65 is closed and the on-off valve 52 is open, the compressed oxygen-containing gas is flowed through the seventh pipe 51, the third pipe 33, the gas-liquid separator 32, and the discharge pipe 30, and supplied to a position above the catalyst layer 22 of the packed tower 20.

[0047] In the apparatus 10 of the embodiment, the "liquid supply unit 40" described above is composed of a supply pipe 43, a first pipe 44, a second pipe 45, a first on-off valve 46, a second on-off valve 47, and a pump 48. The "pressure boosting gas supply unit 50" is composed of a compressor 61, a fifth pipe 62, a seventh pipe 51, a third pipe 33, a gas-liquid separator 32, and a discharge pipe 30. The "gas supply unit 60" is composed of a compressor 61, a fifth pipe 62, a sixth pipe 63, and a supply pipe 43. The "switching unit 70" is composed of a shut-off valve 65 of the sixth pipe 63 and an on-off valve 52 of the seventh pipe 51.

[0048] The liquid supply unit 40 supplies either the first liquid 41 or the second liquid 42 when the gas supply unit 60 is supplying oxygen-containing gas.

[0049] The booster gas supply unit 50 of this embodiment supplies the same oxygen-containing gas supplied by the gas supply unit 60 to the packed tower 20 as the booster gas. With this configuration, the booster gas can be pressurized by a single compressor 61, eliminating the need to add a separate compressor dedicated to the booster gas. The booster gas supply unit 50 can be configured simply by adding piping and an on-off valve 52, resulting in a simple device configuration and cost advantages. It should be noted that the present invention does not exclude the use of gases other than oxygen-containing gas, such as inert gases, as the booster gas. It goes without saying that an appropriate gas depending on the processing content can be used as the booster gas.

[0050] The processing apparatus 10 may further include a second heater 80 (corresponding to a heater) for heating the packed column 20. The second heater 80 consists of a heater. By heating the packed column 20 with the second heater 80, it is possible to easily set not only the temperature conditions during normal operation, but also the temperature conditions when starting or restarting the processing apparatus 10. Note that the second heater 80 is not limited to an external heating type located outside the packed column 20 as shown in the figure. An internal heating type second heater 80 located inside the packed column 20 can also be used.

[0051] The material of parts of reactors (e.g., packed columns and piping) that come into contact with high-temperature liquids or gases is not particularly limited as long as it is a commonly used material, but it is preferable that it be made of metal, such as iron, copper, stainless steel, Hastelloy, Inconel, titanium, and zirconium. Among these, stainless steel, Hastelloy, Inconel, and titanium are preferred, with stainless steel and titanium being particularly preferred. Depending on the wastewater treatment conditions, glass or resin may also be used.

[0052] Next, a method for starting or restarting the processing apparatus 10, which is another embodiment, will be described step by step. This method for starting or restarting the processing apparatus 10 is suitably used for wet oxidation treatment.

[0053] (Boost process) First, a pressurizing gas is supplied via the discharge pipe 30 to a position above the catalyst layer 22, thereby increasing the internal pressure of the packed tower 20. The solid catalyst 21 contained in the catalyst layer 22 can preferably be the one described in "Treatment Device 10".

[0054] If the booster gas is supplied below the catalyst layer 22, the following problems occur. When the processing device 10 is started for the first time, the solid catalyst 21 in the catalyst layer 22 floats up and moves when there is no liquid in the packed column 20. This causes the solid catalyst 21 to wear down and collapse. Also, when the processing device 10 is restarted after being stopped, large bubbles are formed when there is still liquid in the packed column 20, and these bubbles shock the solid catalyst 21. This causes the solid catalyst 21 to wear down and collapse. On the other hand, if the booster gas is supplied above the catalyst layer 22, the solid catalyst 21 in the catalyst layer 22 does not float up and move, nor is it shocked by large bubbles. This reduces damage to the solid catalyst and suppresses the decrease in activity.

[0055] In the pressurization process, the time required from the start of the inflow of the pressurizing gas into the catalyst layer 22 until the target pressure is reached is preferably 60 minutes or more, more preferably 80 minutes or more, and even more preferably 85 minutes or more. Furthermore, there is no particular upper limit to the required time, but it is preferably 180 minutes or less, more preferably 150 minutes or less, even more preferably 120 minutes or less, particularly preferably less than 120 minutes, and most preferably 110 minutes or less. When pressurizing from the supply port side of the packed column 20, the required time is preferably 120 minutes or more. By keeping the required time within the above range, damage to the solid catalyst can be reduced and the decrease in activity can be suppressed.

[0056] In the pressurization process, after the internal pressure of the packed column 20 reaches the set pressure (P) by supplying pressurizing gas to a position above the catalyst layer 22, the supply of oxygen-containing gas is switched to a position below the catalyst layer 22. The set pressure (P) at this time is preferably 0.2 MPaG to 20 MPaG, more preferably 1 MPaG to 20 MPaG, even more preferably 3 MPaG to 10 MPaG, and particularly preferably 4 MPaG to 9 MPaG. G stands for Gauge.

[0057] With this configuration, even if the supply of oxygen-containing gas is switched to a position below the catalyst layer 22, the solid catalyst 21 in the catalyst layer 22 will not float up and move, nor will it be subjected to shocks by large bubbles. This reduces damage to the solid catalyst and suppresses the decrease in activity.

[0058] The set pressure (P) at the time of switching does not have to be the same as the final pressure during steady-state operation. For example, the set pressure (P) can be set to 6 MPaG (gauge pressure, the same applies hereafter), and after the internal pressure of the packed column 20 reaches 6 MPaG, the supply of oxygen-containing gas to a position below the catalyst layer 22 can be switched. After that, the pressure can be gradually increased to, for example, 7 MPaG, which is the final pressure during steady-state operation.

[0059] In the pressurization process, the same oxygen-containing gas as the oxygen-containing gas is supplied to the packed tower 20 as the pressurizing gas. With this configuration, as described above, the pressurizing gas can be pressurized by a single compressor 61, resulting in a simpler equipment configuration and cost advantages.

[0060] (First water flow process) Next, the first liquid 41 is supplied to a position below the catalyst layer 22 and passed through the discharge pipe 30 connected to a position above the catalyst layer 22. At this time, the time required from the start of supplying the first liquid 41 until the packed tower 20 is filled with the first liquid 41 and the first liquid 41 passes through the discharge pipe 30 is preferably 20 minutes or more, more preferably 30 minutes or more, and even more preferably 35 minutes or more. Furthermore, the required time is preferably 180 minutes or less, and more preferably 120 minutes or less. By keeping the required time within the above range, a decrease in the treatment capacity of the wastewater treatment can be more effectively prevented. The first liquid 41 can preferably be the one described in "Treatment device 10".

[0061] In the first water supply step, the first liquid 41 is supplied while an oxygen-containing gas is supplied to a position below the catalyst layer 22.

[0062] If the first liquid 41 is introduced after increasing the internal pressure of the packed column 20 and then shutting off the supply and discharge of oxygen-containing gas, the inside of the packed column 20 and other components will be further pressurized. Therefore, it is necessary to increase the pressure resistance of the equipment. On the other hand, if the first liquid 41 is introduced while oxygen-containing gas is being supplied, that is, while oxygen-containing gas is circulating inside the packed column 20, the inside of the packed column 20 and other components will not be excessively pressurized. Therefore, it is not necessary to increase the pressure resistance of the equipment more than necessary.

[0063] In the first water flow step, the flow rate of the oxygen-containing gas supplied to the catalyst layer 22 is preferably 0.1 to 10, more preferably 0.5 to 5, and even more preferably 0.7 to 3, in terms of O2 / COD(Cr) (oxygen content of oxygen-containing gas / chemical oxygen demand). By keeping the flow rate of the oxygen-containing gas within the above range, a decrease in the treatment capacity of the wastewater treatment can be more effectively prevented.

[0064] Furthermore, the pressure inside the packed tower 20 during the first water flow process is preferably 0.2 MPaG to 20 MPaG, more preferably 1 MPaG to 20 MPaG, even more preferably 3 MPaG to 10 MPaG, and particularly preferably 4 MPaG to 9 MPaG. By keeping the pressure inside the packed tower 20 within the above range, a decrease in the wastewater treatment capacity can be more effectively prevented.

[0065] (Heating process) After the first water flow process and before the second water flow process described later, the packed tower 20 is heated while the first liquid 41 has passed through the discharge pipe 30.

[0066] This heating step involves heating the first liquid 41 with the first heater 49 and heating the packed column 20 from the outside with the second heater 80. By providing this heating step, the temperature conditions for starting or restarting the processing device 10 can be easily set.

[0067] In the heating step, the temperature inside the packed column 20 is preferably 80°C to 400°C, and more preferably 200°C to 300°C. Having the maximum temperature inside the packed column 20 within this range results in superior processing capacity for the second liquid 42 in the second water flow step, which will be described later.

[0068] The pressure inside the packed column 20 during the heating process is preferably 0.2 MPaG to 1 MPaG when the processing temperature is 95°C or higher and less than 170°C, and preferably 1 to 5 MPaG when the processing temperature is 170°C or higher and less than 230°C. Furthermore, when the processing temperature is 230°C or higher, a pressure greater than 5 MPaG is preferred. There is no particular upper limit to the pressure when the processing temperature is 230°C or higher, but it is preferably 21 MPaG or less, more preferably 10 MPaG or less, and even more preferably 8 MPaG or less. Furthermore, when the processing temperature is 230°C or higher, the upper limit to the pressure may be 2 times or less the saturated vapor pressure at the temperature of the wastewater in the catalyst layer, or 1.5 times or less. By keeping the pressure inside the packed column 20 within the above range, the wastewater can maintain a liquid phase in the reactor, and a decrease in the processing capacity of the wastewater treatment can be more effectively prevented. Note that the upper limit of the pressure within the processing temperature range is a guideline and should be determined by balancing processing efficiency and the pressure resistance of the equipment.

[0069] (Second water flow process) After the first water flow step, a second liquid 42 is supplied to a position below the catalyst layer 22, the second liquid 42 having a COD(Cr) greater than that of the first liquid 41.

[0070] By performing a second water supply process to supply the second liquid 42 after the first water supply process, the wastewater treatment capacity can be improved, and a decrease in treatment capacity can be prevented. This is because, compared to the case where the second liquid 42 (wastewater) is supplied to the catalyst layer 22 first, supplying the first liquid 41 to the catalyst layer 22 first prevents deterioration of the catalyst due to the adhesion of organic components in the wastewater.

[0071] In the second water flow process, the LHSV (Liquid Hourly Space Velocity) of the second liquid 42 in the catalyst layer 22 is 0.1hr. -1 ~10 hours -1 Preferably, 0.5hr -1 ~5hr -1It is more preferable that the LHSV of the second liquid 42 in the catalyst layer 22 is within the above range, which makes it possible to maintain excellent wastewater treatment capacity for a longer period of time.

[0072] In the second water supply step, the second liquid 42 is supplied while an oxygen-containing gas is supplied to a position below the catalyst layer 22.

[0073] Similar to the first water flow process, introducing the second liquid 42 while oxygen-containing gas is supplied, i.e., while oxygen-containing gas is circulating within the packed column 20, prevents excessive pressurization inside the packed column 20. In other words, introducing the second liquid 42 when oxygen-containing gas is not supplied may cause excessive pressurization inside the packed column 20. Therefore, maintaining the flow of oxygen-containing gas eliminates the need to unnecessarily increase the pressure resistance of the equipment.

[0074] Furthermore, the flow rate of the oxygen-containing gas supplied to the catalyst layer 22 in the second water flow step can be appropriately set to the flow rate of the oxygen-containing gas supplied to the catalyst layer 22 as shown in the first water flow step.

[0075] The pressure inside the packed column 20 during the second water flow process is preferably 0.2 MPaG to 20 MPaG, more preferably 1 MPaG to 20 MPaG, even more preferably 3 MPaG to 10 MPaG, and particularly preferably 4 MPaG to 9 MPaG. By keeping the pressure inside the packed column 20 within the above range, a decrease in the wastewater treatment capacity can be more effectively prevented. (Wastewater treatment process) Once the second water flow process is complete, the process moves to the wastewater treatment process. In the wastewater treatment process, the treated liquid after the wet oxidation treatment is cooled by a cooler 31 via the discharge pipe 30, and then subjected to gas-liquid separation by a gas-liquid separator 32. In the gas-liquid separator 32, the liquid level is detected by the liquid level controller LC and maintained at a constant liquid level by the liquid level control valve 36.

[0076] Furthermore, the pressure is detected by the pressure controller PC, and the pressure control valve 35 maintains the pressure in the gas-liquid separator 32 and the packed column 20 at the final pressure during steady operation (e.g., 7 MPaG). The treated liquid thus processed is discharged from the fourth pipe 34. In the wastewater treatment process, the LHSV in the catalyst layer 22 of the second liquid 42 is the same as in the second water flow process described above.

[0077] The pressure inside the packed column 20 during the wastewater treatment process is preferably 0.2 MPaG to 20 MPaG, more preferably 1 MPaG to 20 MPaG, even more preferably 3 MPaG to 10 MPaG, and particularly preferably 4 MPaG to 9 MPaG. By keeping the pressure inside the packed column 20 within the above range, a decrease in the wastewater treatment capacity can be more effectively prevented.

[0078] The following describes in more detail some of the components that constitute the wastewater treatment apparatus and the method for starting or restarting the apparatus according to the present invention.

[0079] (Solid catalyst) The solid catalyst 21 can be used without particular limitations as long as it is commonly used in wastewater treatment. In particular, from the viewpoint of having excellent treatment performance, the solid catalyst 21 preferably includes one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof, and at least one selected from the group consisting of activated carbon, and more preferably one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof.

[0080] The solid catalyst 21 may contain, in addition to the above-mentioned components (also referred to as the first component), other components different from the above-mentioned components (also referred to as the second component). As this second component, at least one metal selected from manganese, cobalt, nickel, tungsten, copper, cerium, silver, platinum, palladium, rhodium, gold, iridium, ruthenium, etc., or a compound of these metals, can be used. In such a catalyst containing the second component, it is preferable to use the second component in a ratio of 25 to 0.05% by weight to 75 to 99.95% by weight of the first component. By using the solid catalyst 21 as described above, a better wastewater treatment effect can be obtained.

[0081] Furthermore, the shape of the solid catalyst 21 is not particularly limited, and any solid catalyst in a shape commonly used for wastewater treatment can be used. Typically, spherical, pellet-shaped, or ring-shaped solid catalysts are used, and honeycomb-shaped catalysts may also be used. When the solid catalyst 21 is pellet-shaped, it is preferable that the diameter is 1 mm to 10 mm and the length is 2 mm to 12 mm, and more preferably that the diameter is 2 mm to 8 mm and the length is 4 mm to 10 mm. A solid catalyst 21 having the above shape can provide a better wastewater treatment effect.

[0082] (COD(Cr)) In this specification, COD stands for Chemical Oxygen Demand, an indicator of the amount of organic matter in water. COD(Cr) is one type of COD and indicates the amount of oxygen required for potassium dichromate to oxidize and / or decompose the target oxide (e.g., organic compounds and nitrogen compounds in wastewater). COD(Cr) can be measured by known methods, for example, by following the method described in the test examples.

[0083] (First liquid) The first liquid 41 may be any liquid whose COD(Cr) is lower than that of the second liquid 42, but as mentioned above, it is preferable to use deionized water, pure water, ultrapure water, industrial water, well water, or tap water. Furthermore, the COD(Cr) of the first liquid 41 is preferably 100 mg / L or less, more preferably 10 mg / L or less, even more preferably 5 mg / L or less, particularly preferably 1 mg / L or less, and most preferably 0 mg / L (below the detection limit of the COD analyzer).

[0084] (Second liquid) The second liquid 42 is any liquid whose COD(Cr) is greater than that of the first liquid 41, but it is preferably between 1,000 mg / L and 100,000 mg / L, more preferably between 5,000 mg / L and 100,000 mg / L, and even more preferably between 10,000 mg / L and 60,000 mg / L. By having the COD(Cr) of the first liquid 41 and the second liquid 42 fall within the above ranges, the effects of the present invention can be obtained more effectively.

[0085] (Oxygen-containing gas) In this specification, an oxygen-containing gas is a gas containing molecular oxygen and / or ozone. Such gases may include pure oxygen, oxygen-enriched gas, air, hydrogen peroxide, or oxygen-containing gases produced in other plants. The type of oxygen-containing gas is not particularly limited, but from an economic standpoint, the use of air is recommended.

[0086] The oxygen content in the oxygen-containing gas is not particularly limited, but it is preferably 1% to 100%, 5% to 80%, and 10% to 50% in terms of volume ratio ((volume of oxygen / volume of oxygen-containing gas) × 100 (%)) relative to the total oxygen-containing gas.

[0087] Although embodiments of the present invention have been described in detail above, this is descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0088] <Example Test> The effects of the present invention will be explained using the following test examples. However, the technical scope of the present invention is not limited to the following test examples. In the following test examples, unless otherwise specified, the operations were carried out at room temperature (25°C). Also, unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0089] Figure 2 shows the details of the packed column 20 (wet oxidation reactor) used in Test Example 1. The packed column 20 is cylindrical with a diameter of 600 mm and a length of 10,000 mm. SUS balls (8.5 mm in diameter, spherical) were packed to a height of 100 mm on a support base made of grid and wire mesh.

[0090] Next, 2000 liters of solid catalyst 21 were packed onto the SUS ball layer to a height of 7074 mm to form a catalyst layer 22. The solid catalyst 21 used consisted mainly of titania and platinum, with a weight ratio of 99.0:1.0 in terms of TiO2:Pt. The solid catalyst was in the form of pellets with a diameter of 4 mmφ and a length of 6 mm.

[0091] Then, the same SUS balls as described above were packed 300 mm in height on top of this catalyst layer 22.

[0092] <Wastewater Treatment Test> A wastewater treatment test of the wet oxidation treatment apparatus 10 shown in Figure 1, which has the packed column 20 prepared as described above, was carried out according to the following procedure.

[0093] (Test Example 1) In Test Example 1, the wet oxidation treatment apparatus 10 was started according to the following procedures (1) to (4).

[0094] (1) Pressure boosting process Air was supplied from the fifth pipe 62 (oxygen-containing gas introduction line), and after being pressurized by the compressor 61, the shut-off valve 65 was closed and the on-off valve 52 was opened, and pressurization was started from the treated water discharge line (discharge pipe 30) side of the packed tower 20 at atmospheric pressure through the seventh pipe 51 (compressed air filling line). The pressurization was controlled by detecting the pressure with a pressure controller (PC) (pressure sensor) and operating the pressure control valve 35 to maintain a pressure of 7 MPaG. The time required for this pressurization was 90 minutes. G stands for Gauge.

[0095] When the internal pressure of the packed tower 20 reached 7 MPaG, the shut-off valve 52 was closed, and the shut-off valve 65 and flow control valve 64 were opened, thereby initiating the supply of air from the supply port side (supply piping 43 side) of the packed tower 20. The air was supplied at a flow rate corresponding to O2 / COD(Cr) (amount of oxygen in the air / chemical oxygen demand) = 1.1 relative to the COD(Cr) (chemical) oxygen demand of the wastewater to be treated. G stands for Gauge.

[0096] Here, COD(Cr) was measured using a HACH DR3900 COD analyzer. Specifically, the measurement was performed using the following procedure: 0.20 mL of the analyte solution was added to a vial of COD decomposition reagent (HACH) using a pipette and thoroughly mixed. The mixture was then heated at 150°C for 2 hours using a DRB200 reactor (HACH). After thoroughly mixing the liquid in the vial, COD(Cr) was calculated by colorimetric measurement using the DR3900 (HACH). The COD(Cr) described later was also measured using the same method.

[0097] After the pressurization process was completed, the first pure water flow process was carried out in the packed column 20 according to the following procedure.

[0098] (2) First water flow process With air supply continuing from the supply port side of the packed column 20, pure water (COD(Cr) ≤ 1 mg / L) is pumped 48 to 4 m 3The supply was started at a flow rate of / h. Pure water was passed through the packed column 20 until it filled the inside of the column and passed through the discharge pipe 30 (treated water discharge line). The time required from the start of pure water supply until the inside of the packed column 20 was filled with pure water and the pure water passed through the discharge pipe 30 was 40 minutes. During the first water flow process, the pressure inside the packed column 20 was approximately 7 MPaG.

[0099] After the first water flow process was completed, the packing column 20 underwent a heating process according to the following procedure.

[0100] (3) Heating process Using the first heater (heat exchanger) 49 and the second heater (heater) 80, the pure water and the packed column 20 were heated while the pure water was passed through the discharge pipe 30 (treated water discharge line), and the temperature inside the packed column was adjusted to reach a maximum temperature of 250°C. During the heating process, the pressure inside the packed column 20 was approximately 7 MPaG.

[0101] After confirming with a temperature sensor that the temperature near the supply port of the packed column 20 reached 240°C during the heating process, the second water flow process was carried out according to the following procedure.

[0102] (4) Second water flow process The liquid supplied from pump 48 was switched from pure water to wastewater (COD(Cr) = 40,000 mg / L). More specifically, the wastewater sent from the second pipe 45 (wastewater supply line) was pressurized by pump 48 and supplied from the supply port side of the packed column 20. The LHSV of the wastewater in the catalyst layer 22 was 2.0 hr. -1 During the second water flow process, the pressure inside the packed tower 20 was approximately 7 MPaG.

[0103] The processing apparatus was started using the method described above. Furthermore, the wet oxidation treatment was continued using the method described below.

[0104] (5) Wastewater treatment process Similar to the second water supply process, the wastewater sent from the second pipe 45 (wastewater supply line) was pressurized by a pump and supplied from the supply port side of the packed tower 20. The LHSV of the wastewater in the catalyst layer 22 was 2.0hr. -1 The wastewater supply was carried out for 1000 hours from start to finish. After the wet oxidation treatment, the treated liquid was cooled in a cooler 31 via the discharge pipe 30 (treated liquid line), and then subjected to gas-liquid separation treatment in a gas-liquid separator 32. In the gas-liquid separator 32, the liquid level was detected by a liquid level controller (LC) and the liquid level control valve 36 was operated to maintain a constant liquid level, and the pressure was detected by a pressure controller (PC) and the pressure control valve 35 was operated to maintain a pressure of approximately 7 MPaG. After that, the treated liquid was discharged from the fourth pipe 34 (treated liquid discharge line).

[0105] The COD(Cr) content in the treated liquid, which was discharged 1000 hours after the start of treatment using the method described above, was measured. The results are shown in Table 1.

[0106] Furthermore, the COD(Cr) treatment rate of the treated liquid discharged after 1000 hours was calculated using the following formula. In the formula, "COD(Cr) of wastewater" refers to the COD(Cr) of the wastewater before treatment by the method described above. The results are shown in Table 1.

[0107]

number

[0108] (Test Example 2) The wastewater treatment test was conducted in the same manner as in Test Example 1, except that the pressure was increased to 7 MPaG by supplying oxygen-containing gas from the supply port side of the packed tower 20 over 120 minutes during the pressurization process described above. The results obtained are shown in Table 1.

[0109] (Test Example 3) The wastewater treatment test was conducted in the same manner as in Test Example 2, except that the operating procedure was changed to the order of the first water flow process, pressurization process, temperature increase process, and second water flow process. The results obtained are shown in Table 1.

[0110] (Test example 4) The wastewater treatment test was conducted in the same manner as in Test Example 1, except that the operating procedure was changed to the order of pressurization step, heating step, first water flow step, and second water flow step. The results obtained are shown in Table 1. In Test Example 4, the heating step was carried out in the packed column 20 without the presence of pure water.

[0111] (Test Example 5) The wastewater treatment test was conducted in the same manner as in Test Example 1, except that the operating procedure was changed to the order of pressurization step, first water flow step, second water flow step, and temperature rise step. The results obtained are shown in Table 1.

[0112] [Table 1]

[0113] As shown in Table 1, the results of Test Examples 1 to 4 indicate that the COD(Cr) of the treated liquid discharged 1000 hours after the start of treatment was sufficiently reduced, and that the treatment capacity of the wastewater treatment was maintained. Furthermore, the results of Test Example 1 showed that the wastewater treatment capacity was maintained in particular, compared to Test Examples 2 to 5, in terms of both the treated water COD(Cr) (mg / L) and the COD(Cr) treatment rate (%). [Explanation of Symbols]

[0114] 10 Processing Unit 20 Packed tower 21 Solid catalysts 22 Catalyst layer 23 Filling layer 24 Filling layer 30 Discharge piping 31 Cooler 32 Gas-liquid separator 33 Third Piping 34. Fourth pipe 35 Pressure control valve 36 Liquid level control valve 40 Liquid supply section 41 The first liquid 42 The second liquid 43 Supply piping 44. First Piping 45 Second Piping 46. ​​First shut-off valve 47. Second shut-off valve 48 pumps 49 1st heater 50. Gas supply unit for boosting pressure 51. Piping No. 7 52 Shut-off valves 60 Gas Supply Department 61 Compressor 62. Fifth Piping 63. Piping No. 6 64 Flow control valve 65 Shut-off valve 70 Switching section 80 Second heater COD-treated water LC liquid level controller PT temperature controller.

Claims

1. A packed tower having a catalyst layer filled with a solid catalyst, A discharge pipe connected to a position above the catalyst layer, A processing apparatus comprising a liquid supply unit located below the catalyst layer, capable of supplying either a first liquid or a second liquid having a COD(Cr) greater than the COD(Cr) of the first liquid.

2. The packed column further includes a booster gas supply unit that supplies booster gas to the packed column to increase the internal pressure of the packed column. The apparatus according to claim 1, wherein the pressurizing gas supply unit supplies the pressurizing gas to a position above the catalyst layer via the discharge pipe.

3. A gas supply unit that supplies oxygen-containing gas to a position below the catalyst layer, The apparatus according to claim 2, further comprising a switching unit capable of switching between supplying the pressurized gas to a position above the catalyst layer by the pressurized gas supply unit and supplying the oxygen-containing gas to a position below the catalyst layer by the gas supply unit.

4. The apparatus according to claim 3, wherein the liquid supply unit supplies either the first liquid or the second liquid when the oxygen-containing gas is supplied by the gas supply unit.

5. The apparatus according to claim 3, wherein the pressurizing gas supply unit supplies the same oxygen-containing gas as the oxygen-containing gas supplied by the gas supply unit to the packed tower as the pressurizing gas.

6. The apparatus according to any one of claims 1 to 5, further comprising a heater for heating the packed column.

7. The apparatus according to any one of claims 1 to 5, wherein the first liquid is deionized water, pure water, ultrapure water, industrial water, well water, or tap water.

8. The apparatus according to any one of claims 1 to 5, wherein the solid catalyst comprises one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof, and at least one selected from the group consisting of activated carbon.

9. An apparatus for use in wet oxidation treatment, according to any one of claims 1 to 5.

10. A method for starting or restarting a processing apparatus having a packed tower with a catalyst layer filled with a solid catalyst, A first water flow step involves supplying a first liquid to a position below the catalyst layer and passing the first liquid through a discharge pipe connected to a position above the catalyst layer, A method for starting or restarting a processing device, comprising: a second water supply step, after the first water supply step, supplying a second liquid having a COD(Cr) greater than the COD(Cr) of the first liquid to a position below the catalyst layer.

11. A method for starting or restarting the processing apparatus according to claim 10, comprising a pressurization step performed prior to the first water flow step, in which a pressurizing gas is supplied via the discharge pipe to a position above the catalyst layer to increase the internal pressure of the packed tower.

12. A method for starting or restarting an apparatus according to claim 11, wherein, in the pressurization step, after the internal pressure of the packed column reaches a set pressure (P) by supplying the pressurizing gas to a position above the catalyst layer, the supply of oxygen-containing gas is switched to a position below the catalyst layer.

13. In the first water supply step, the first liquid is supplied while the oxygen-containing gas is supplied to a position below the catalyst layer. A method for starting or restarting the apparatus according to claim 12, wherein in the second water supply step, the oxygen-containing gas is supplied to a position below the catalyst layer, and the second liquid is supplied.

14. A method for starting or restarting the processing apparatus according to claim 12, wherein in the pressurization step, the same oxygen-containing gas as the oxygen-containing gas is supplied to the packed tower as the pressurizing gas.

15. A method for starting or restarting an apparatus according to any one of claims 10 to 14, further comprising a heating step of heating the packed tower after the first water flow step and before the second water flow step, while the first liquid has been passed through the discharge pipe.

16. A method for starting or restarting an apparatus according to any one of claims 10 to 14, wherein the first liquid is deionized water, pure water, ultrapure water, industrial water, well water, or tap water.

17. A method for starting or restarting an apparatus according to any one of claims 10 to 14, wherein the solid catalyst comprises one or more selected from the group consisting of titanium, iron, aluminum, silicon, zirconium, oxides thereof, and composite oxides thereof, and at least one selected from the group consisting of activated carbon.

18. A method for starting or restarting an apparatus according to any one of claims 10 to 14, used in a wet oxidation treatment.

Images