JP2017100099A - Water treatment system and water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system and method, capable of supplying an appropriate amount of ozone taking not only the solid component of surplus sludge but also soluble organic substances into consideration.SOLUTION: The water treatment system including an ejector 7, an inflow part 12, a detection part 18, a storage tank 8, and a tank 16 for an ozone treatment of soluble organic substances brings the sludge-containing treatment water drawn from an aeration tank 1 into contact with ozone so as to decompose the sludge. The sludge-containing treatment water drawn from an aeration tank 1 is subjected to a plurality of first ozone treatments and then reserved in a storage tank 8. The state in the storage tank 8 is detected by the detection part 18. The reserved sludge-containing treatment water is subjected to a second ozone treatment which is different from the first ozone treatment based on the detection result.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water treatment system and a water treatment method for treating water such as waste water containing an organic substance.

  As a method for treating water such as waste water containing organic matter, a treatment method using microorganisms such as a standard activated sludge method is widely used. In the treatment method using microorganisms, microorganisms can grow with the treatment of water and a large amount of excess sludge can be generated.

  Since excess sludge is unnecessary for water treatment, it is discharged out of the water treatment system and is incinerated and disposed of as landfill. Since disposal of such excess sludge requires a great deal of energy, cost, and new land, reduction of the generation amount of excess sludge is required.

  As one method for reducing the amount of excess sludge generated, sludge volume reduction treatment using ozone is known. Specifically, a process is known in which excess sludge in which microorganisms and the like are collected is supplied with ozone to decompose to reduce the volume of excess sludge.

  The sludge volume reduction treatment method using ozone is roughly divided into two types, a line injection type and a batch type. The line injection type treatment method is, for example, a method in which ozone is directly injected into a pipe for returning the sludge-containing treated water from the sedimentation tank to the aeration tank. The batch type treatment method is, for example, drawn from the aeration tank. This is a method of circulating the sludge containing treated water in contact with ozone in the storage tank for a certain period of time.

  In the line injection type method, the sludge-containing treated water separated from the treated water in the sedimentation tank and concentrated is brought into contact with ozone in the middle of the pipe returning to the aeration tank, and the surplus contained in the sludge-containing treated water Sludge is decomposed (for example, refer to Patent Document 1).

  In the batch type method, the sludge-containing treated water is drawn from the aeration tank into the storage tank, and the extracted sludge-containing treated water is circulated in the storage tank for a certain period of time. In the middle of the circulation, the sludge-containing treated water and ozone are repeatedly contacted to decompose excess sludge contained in the sludge-containing treated water. At this time, ozone may be brought into contact with the concentrated sludge containing treated water separated from the treated water in the settling tank instead of the sludge containing treated water extracted from the aeration tank (for example, see Patent Document 2). In addition, ozone is blown into the liquid phase contact area of the reaction tank in which the sludge-containing treated water is stored, so that excess sludge is oxidized and decomposed and foamed to form a foam contact area above the liquid phase contact area. In addition, a batch-type method for treating excess sludge with ozone has also been devised (see, for example, Patent Document 3).

JP-A-9-150185 JP 2001-191097 A Japanese Patent Laid-Open No. 7-232184

  However, there is room for improvement in the conventional sludge volume reduction processing method using ozone. When ozone is reacted with surplus sludge in which microorganisms and the like are collected, solid components including microorganisms are decomposed, and components in the microorganisms (soluble organic substances) including nucleic acids and polymer proteins appear in the treated water. The soluble organic matter generated by the decomposition of the solid component becomes a substrate for microorganisms and the like, and thus may excessively promote the growth of microorganisms causing excess sludge.

  In the conventional line injection type sludge volume reduction processing method, ozone is supplied once into the sludge-containing treated water to perform the treatment. Therefore, the solid component in the sludge-containing treated water and ozone react with each other, but the soluble organic matter generated by the decomposition of the solid component may remain undecomposed. When the treated water containing undecomposed soluble organic matter is returned to the wastewater treatment system (aeration tank), there is a risk of excessively promoting the growth of microorganisms and the like that cause the generation of excess sludge. If the amount of ozone supplied once to reduce undecomposed soluble organic matter is increased, it is not easy to predict the ozone supply amount in consideration of the soluble organic matter caused by decomposition of solid components. Therefore, there is a possibility that water quality will be deteriorated by supplying ozone more than necessary. That is, in the conventional line injection type sludge volume reduction treatment method, it is difficult to supply an appropriate amount of ozone in consideration of not only solid components of excess sludge but also soluble organic matter.

  In the conventional batch type sludge volume reduction treatment method, ozone is supplied multiple times through the ozone treatment circulation process, but in the same way as the conventional line injection type sludge volume reduction treatment method, There is a possibility that the soluble organic matter generated by the decomposition of the components may remain undecomposed. When the treated water containing undecomposed soluble organic matter is returned to the wastewater treatment system (aeration tank), there is a risk of excessively promoting the growth of microorganisms and the like that cause the generation of excess sludge. When increasing the amount of ozone per supply to reduce undecomposed dissolved organic matter, or increasing the number of times ozone is supplied in the circulation process, the amount of dissolved organic matter generated by the decomposition of solid components was also anticipated. Since it is not easy to predict the amount of ozone supplied above, there is a risk of water quality deterioration by supplying more ozone than necessary. That is, even with the conventional batch-type sludge volume reduction treatment method, it is difficult to supply an appropriate amount of ozone in consideration of not only solid components of excess sludge but also soluble organic matter.

  The present invention has been made to solve the above-described problems, and is a water treatment capable of supplying an appropriate amount of ozone in consideration of not only solid components of excess sludge but also soluble organic matter. It is an object to provide a system and a water treatment method.

  The water treatment system according to the present invention includes a first ozone treatment section, a storage tank, a transport section, and a second ozone treatment section, and includes sludge-containing treated water in an aeration tank into which water to be treated has flowed. Decompose the sludge-containing treated water by contacting with ozone. The first ozone treatment unit performs the first ozone treatment on the sludge-containing treated water extracted from the aeration tank. A storage tank stores the sludge containing treated water which performed the 1st ozone treatment. The transport unit performs a transport process of drawing a part of the sludge-containing treated water stored in the storage tank from the lower side of the storage tank and flowing into the upper side of the storage tank a plurality of times. A 2nd ozone treatment part performs the 2nd ozone treatment different from a 1st ozone treatment to the sludge containing treated water withdrawn from the downward side of the storage tank after performing a transport process in multiple times.

  The water treatment method according to the present invention includes a first ozone treatment step, a storage step, a transport step, and a second ozone treatment step, and is applied to sludge-containing treated water in an aeration tank into which water to be treated has flowed. The sludge containing treated water is decomposed by contacting with ozone. In the first ozone treatment step, the first ozone treatment is performed on the sludge-containing treated water extracted from the aeration tank. In the storage step, the sludge-containing treated water subjected to the first ozone treatment is stored in a storage tank. In the transport process, a part of the sludge-containing treated water stored in the storage tank is pulled out from the lower side of the storage tank and transported to the upper side of the storage tank a plurality of times. In the second ozone treatment step, the second ozone treatment different from the first ozone treatment is performed on the sludge-containing treated water extracted from the lower side of the storage tank after carrying out the transportation treatment a plurality of times.

  According to the present invention, a part of the sludge-containing treated water stored in the storage tank is pulled out from the lower side of the storage tank and is transported to the upper side of the storage tank a plurality of times, thereby performing the transport process on the upper side of the storage tank. Solid components in the sludge-containing treated water are trapped by the generated foam, and soluble organic substances in the sludge-containing treated water can be separated to the lower side of the storage tank. Further, the separation timing can be detected by the detection unit. Therefore, it is possible to perform ozone treatment suitable for solid components and ozone treatment suitable for soluble organic matter, and supply an appropriate amount of ozone after considering not only solid components of excess sludge but also soluble organic matter. Can be done.

It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 1. FIG. It is a flowchart which shows the process sequence of a control apparatus. It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 2. FIG. It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 3. FIG. It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 4. FIG. It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 5. FIG. It is a schematic diagram which shows the structure of the water treatment system which concerns on Embodiment 6. FIG.

  Hereinafter, embodiments of a water treatment system and a water treatment method disclosed in the present application will be described in detail with reference to the accompanying drawings. The following embodiments are merely examples, and the present invention is not limited to these embodiments.

Embodiment 1 FIG.
A water treatment system according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram illustrating a device configuration, a control system configuration, a flow system configuration, and the like of the water treatment system according to the first embodiment.

  The water treatment system shown in FIG. 1 includes an aeration tank 1, an air diffuser 2, a storage tank 8, a soluble organic matter ozone treatment tank 16, a solid component-containing foam storage tank 17, a detection unit 18, a control device 19, and the like. .

  Waste water 4 containing organic matter flows into the aeration tank 1. Waste water 4 is an example of water to be treated.

  An air supply device 3 is connected to the air diffuser 2. The air diffuser 2 supplies the air acquired from the air supply device 3 into the aeration tank 1, and makes the aeration tank 1 an aerobic condition. In the aeration tank 1, the wastewater 4 is treated under an aerobic condition by activated sludge that is an aggregate of bacteria and microorganisms, and sludge-containing treated water is generated. As the air supply device 3, a blower, a compressor, a pump, and the like are used depending on the required air supply amount.

  The sludge-containing treated water treated with activated sludge in the aeration tank 1 flows out to the post-treatment unit 201 connected to the aeration tank 1. In the post-treatment unit 201, the sludge containing treated water is separated into the biological treated water 6 and the concentrated sludge containing treated water. Although not shown in FIG. 1 in order to avoid complications, the water treatment system according to the present embodiment includes a return pipe 106 for the treated water containing concentrated sludge separated in the post-treatment unit 201. The pump which returns to the aeration tank 1 via is provided.

  The storage tank 8 is connected to the aeration tank 1 via the extraction pipe 101. On the extraction pipe 101, an extraction pump 5, an ejector 7, and a shut-off electromagnetic valve 23 are arranged. A pull-out portion 11 is provided at the bottom portion on the lower side of the storage tank 8, and an inflow portion 12 is provided on the ceiling portion on the upper side of the storage tank 8. The extraction part 11 and the inflow part 12 are connected via a transport pipe 102. The storage tank 8 stores sludge-containing treated water that has been subjected to first ozone treatment described below.

  On the transport pipe 102, a transport pump 13 and a transport direction electromagnetic valve 14 are provided. Therefore, the combination of the transport pipe 102, the transport pump 13, and the transport direction solenoid valve 14 will be described in detail later. A part of the sludge-containing treated water stored in the storage tank 8 is drawn from the lower side of the storage tank 8. It functions as a transport unit that performs transport processing that flows into the upper side of the storage tank 8 a plurality of times. Further, the transport pipe 102 is connected to the soluble organic substance pipe 103 and the foam storage pipe 104 via the return direction switching valve 15. On the soluble organic pipe 103, there is a flow meter 22. The soluble organic matter pipe 103 is connected to the return pipe 106 via the soluble organic matter ozone treatment tank 16. A defoaming section 24 and a return pump 26 are provided on the return pipe 106. The foam storage pipe 104 is connected to the foam pipe 105 via the solid component-containing foam storage tank 17. A foam pump 25 is provided on the foam pipe 105.

  Above the storage tank 8, there is provided an exhaust ozone pipe 112 for discharging ozone gas that has not been reacted and is released into the air. A detection unit 18 that detects physical properties of the sludge-containing treated water 10 stored on the lower side of the storage tank 8 is provided on the lower side of the storage tank 8. The detection unit 18 is connected to the storage tank 8 via the detection pipe 107 and is connected to the control device 19 via the detection unit output line 108.

  The ejector 7 and the soluble organic matter ozone treatment tank 16 are connected to the switching valve 21. The switching valve 21 is connected to the ejector 7 via the first injection pipe 110 and is connected to the soluble organic matter ozone treatment tank 16 via the second injection pipe 111. The switching valve 21 is connected to the ozone generator 20 via an ozone supply pipe 109.

  The ozone generator 20 operates based on a command from the control device 19 to generate ozone having a required ozone concentration and ozone supply amount. Although not shown in FIG. 1 in order to avoid complication, the control device 19 is interlocked by sequence control, and the transport direction electromagnetic valve 14, the return direction switching valve 15, the switching valve 21, the flow meter 22, etc. It is connected to all devices that operate. The ozone generator 20 functions as an ozone generator according to the present invention, and can generate first ozone used for the first ozone treatment described later and second ozone used for the second ozone treatment.

  The ozone raw material supplied to the ozone generator 20 is not particularly limited. For example, liquid oxygen, oxygen generated by PSA (Pressure Swing Adsorption), or PVSA (Pressure Vacuum Swing Adsorption) can be used. You may arrange | position the additional gas supply part which adds 0.05 to 5% of nitrogen, air, or a carbon dioxide with respect to the oxygen flow rate supplied as needed.

  A cooling unit 202 is connected to the ozone generator 20 via a cooling pipe 113. The cooling unit 202 includes a transport pump that transports a cooling medium for cooling the ozone generator 20, and a cooler that cools the cooling medium that has increased in temperature by absorbing heat generated in the ozone generator 20. Yes. As the cooler, a heat exchange type cooler selected from a liquid-liquid type and a liquid-gas type, or a liquid-fluorocarbon refrigerant type chiller can be used. In addition, a refrigerator can be used when cooling at an extremely low temperature. As an example of the cooling medium, general tap water is used. In addition, water mixed with antifreeze or scale remover, ion-exchanged water, or pure water may be used, or ethylene glycol or ethanol may be used.

  The excess sludge reduction process in the water treatment system of Embodiment 1 is demonstrated. The waste water 4 that has flowed into the aeration tank 1 is biologically treated in the aeration tank 1 to become sludge-containing treated water. At this time, the transport direction solenoid valve 14, the return direction switching valve 15, and the shut-off solenoid valve 23 are closed.

  After the waste water 4 flows into the aeration tank 1, the shut-off electromagnetic valve 23 is opened at a constant cycle, the extraction pump 5 is activated, and the sludge-containing treated water is extracted from the aeration tank 1. The extracted sludge-containing treated water is stored in the storage tank 8 through the extraction pipe 101, the ejector 7, and the inflow portion 12.

  The ozone generator 20 generates gaseous ozone. The generated ozone is sent to the ejector 7 via the first injection pipe 110. The sludge-containing treated water stored in the storage tank 8 contacts and reacts with ozone in a mechanism portion located between the ejector 7 and the inflow portion 12 (first ozone injection method). This treatment is an example of the first ozone treatment according to the present invention, and the mechanism portion located between the ejector 7 and the inflow portion 12 performs the first ozone treatment on the sludge-containing treated water drawn out from the aeration tank 1. It functions as the 1st ozone treatment part to perform.

  The first ozone injection method will be described. In the first ozone injection method, high-concentration ozone is injected at a small gas flow rate into a mechanism portion located between the ejector 7 and the inflow portion 12 to react with the sludge-containing water, so that the solid component in the sludge-containing water is removed. Efficient decomposition can be achieved with a sufficient amount of ozone injection. Here, “no excess or deficiency” means that the amount of the treatment object remaining as unreacted is as close to zero as possible, and the amount of ozone that has been injected but is still unreacted is as close to zero as possible. Say state. Sludge-containing water formations (cells, microorganisms) aggregate to form a block called floc, but the ejector 7 disaggregates the floc and increases the contact area with ozone to efficiently produce ozone and solid components. Can be reacted. That is, in the ejector 7, the water flow of high-pressure sludge-containing water is depressurized at the nozzle portion, and the sucked gaseous ozone is supplied so that the ozone and the sludge-containing water come into contact with each other. The flocs formed by solid components in the sludge-containing water are crushed and broken apart with a sufficient impact force.

When the first ozone injection method is used, the surface area of the solid component that comes into contact with ozone is increased, so that the reaction efficiency between ozone and the solid component is improved. Moreover, since the reaction with the solid component in the sludge containing treated water becomes more efficient as the concentration of ozone in contact is higher, the higher the concentration of ozone, the higher the decomposition of the solid component can be realized with a smaller ozone injection amount. . Here, the ozone injection amount is a value represented by the following formula (1), and the value obtained by multiplying the ozone concentration and the ozone flow rate is the solid component concentration and flow rate in the sludge-containing water (flow rate of the extraction pump 5). Divided by the product of.
Ozone injection amount [mgO ₃ / gSS] = (ozone concentration [mgO ₃ / L] × ozone flow rate [L / min]) ÷ (solid component concentration of sludge-containing water [gSS / L] × flow rate of sludge-containing water [L / Min]) Formula (1)

  In the equation (1) shown above, the higher the ozone concentration, the smaller the required ozone injection amount. Therefore, in the first ozone injection method, high concentration ozone is injected through the ejector 7 with a small gas flow rate, and an ozone injection amount suitable for the solid component in the sludge-containing water can be realized.

  In the first ozone injection method, the concentration of ozone injected from the ozone generator 20 via the ejector 7 is not particularly limited as long as the solid components in the sludge-containing treated water can be efficiently decomposed. However, when considering the decomposition efficiency, 100 mg / L or more and 400 mg / L or less is preferable, and 250 mg / L or more and 400 mg / L or less is more preferable. The higher the ozone concentration, the higher the decomposition efficiency of the solid components in the sludge-containing treated water. Therefore, when the ozone concentration is lower than the above range, the decomposition of the solid components in the sludge-containing treated water becomes insufficient, and surplus sludge in the aeration tank 1 This is because it may not be possible to reduce the weight. Moreover, at present, the ozone concentration that can be generated by the ozone generator 20 is limited to 400 mg / L.

  The gas-liquid flow rate ratio (ozone flow rate / sludge-containing treated water flow rate, hereinafter referred to as “G / L ratio 1”) in the ejector 7 is not particularly limited as long as the solid components in the sludge-containing treated water can be sufficiently decomposed. However, in order to efficiently react the injected high-concentration ozone, it is necessary to reduce the G / L ratio 1, which is preferably 0.01 or more and 0.3 or less, more preferably 0.05 or more and 0.12 or less. . When the G / L ratio 1 is larger than the above range, ozone does not efficiently react with solid components in the sludge-containing treated water in the mechanism portion located between the ejector 7 and the inflow portion 12, and unreacted ozone This is because there is a risk of excessive ozone injection. On the other hand, when the G / L ratio 1 is smaller than the above range, the ozone injection amount is small, and the solid components in the sludge-containing treated water may not be sufficiently decomposed.

  When solid components in the sludge-containing treated water react with ozone, bubbles are generated by the reaction. Therefore, in the storage tank 8, the bubbles 9 are present in the upper portion and the sludge-containing treated water 10 is present in the lower portion. After the bubble 9 is present inside the storage tank 8 and the sludge-containing treated water 10 is present below, the shut-off solenoid valve 23 is closed, and the operation of the extraction pump 5 and the operation of the ozone generator 20 are stopped. Let After stopping the operation of the extraction pump 5 and the operation of the ozone generator 20, the transport direction electromagnetic valve 14 is opened, the transport pump 13 is started, and the storage tank 8 is moved from the extraction portion 11 through the transport pipe 102. A certain sludge containing treated water 10 is extracted. The extracted sludge-containing treated water 10 is again transported from the inflow portion 12 into the storage tank 8 and circulated. By carrying out this transport treatment a plurality of times, the solid components (cells, microorganisms) in the sludge-containing treated water 10 are trapped in the bubbles 9, and the separation of the solid components and soluble organic substances (nucleic acid, polymer protein, etc.) is promoted. . In the storage tank 8 after the separation, the solid component is trapped in the upper bubbles 9 and a dissolved organic substance is present in the lower state.

  The flow rate of the transport pump 13 for separating the solid component and the soluble organic substance is not particularly limited as long as the solid component and the soluble organic substance can be separated. However, when considering the separation performance, the volume a [L] of the liquid phase portion of the sludge-containing water stored in the storage tank 8 is 0.1 a [L / min] or more and 0.7 a [L / min] or less. Is preferably 0.3a [L / min] or more and 0.4a [L / min] or less. This is because, if it is smaller than the above range, it takes time for the separation, so that the processing efficiency may be lowered. When larger than the said range, the quantity of the solid component which flows into the storage tank 8 from the inflow part 12 becomes excessive, a solid component is not fully capture | acquired by the bubble 9, and there exists a possibility that a solid component and soluble organic substance cannot be isolate | separated appropriately. Because there is. If the flow rate of the transport pump 13 is in the above range, the separation of solid components and soluble organic substances in the storage tank 8 is promoted by transporting sludge-containing water of 5a [L] or more and 8a [L] or less. it can.

  Whether or not a solid component is trapped in the upper bubble 9 inside the storage tank 8 and a soluble organic substance is present in the lower portion is detected by the detection unit 18. When the detection unit 18 detects that the bubble trap state has been reached, the detection unit 18 transmits an output signal indicating the bubble trap state to the control device 19.

  A detection mechanism for detecting the separation of the solid component and the soluble organic matter in the sludge-containing water in the storage tank 8 by the detection unit 18 will be described. As the detection unit 18, an SS densitometer that optically directly detects the concentration of solid components in the sludge-containing water below the storage tank 8, or a turbidity that indirectly detects the concentration of solid components in the sludge-containing water below the storage tank 8. A detector such as a meter is installed.

  When the sludge-containing water 10 is extracted from the extraction portion 11 using the transport pump 13 and re-flowed into the storage tank 8 via the inflow portion 12 and circulated, the sludge-containing water is contained in the bubbles 9 formed above the storage tank 8. The solid component is trapped, and the solid component concentration in the sludge-containing water below the storage tank 8 gradually decreases. Since the water treatment system is provided with a detection unit 18 that detects the concentration of the solid component in the sludge-containing water below the storage tank 8, the solid in the sludge-containing water in the storage tank 8 is based on the detected concentration. It can be detected whether the component and the soluble organic substance are sufficiently separated. Based on the detection result of the detector 18, the ozone treatment in the soluble organic matter ozone treatment tank 16 is performed. The concentration of the solid component serving as a reference for the detection unit 18 to detect that the bubble trap state is sufficiently separated is made to selectively react the soluble organic substance and ozone in the soluble organic substance ozone treatment tank 16. There is no particular limitation as long as it is possible. However, considering the reaction efficiency, the SS concentration is preferably 1000 mg / L or less, the turbidity is preferably 10 degrees or less, the SS concentration is 500 mg / L or less, and the turbidity is more preferably 5 degrees or less. When it is larger than the above range, the amount of solid components contained in the sludge-containing water below the storage tank 8 becomes large, and the reaction between ozone and soluble organic matter in the soluble organic matter ozone treatment tank 16 does not occur efficiently. This is because there is a fear.

  Upon receiving the output signal indicating the bubble trap state, the control device 19 activates the ozone generator 20, closes the transport direction electromagnetic valve 14, and opens the return direction switching valve 15 to the soluble organic matter pipe 103 side. The control device 19 further switches the switching valve 21 to connect the ozone supply pipe 109 and the second injection pipe 111. In this state, the lower soluble organic substance is sent to the soluble organic substance ozone treatment tank 16 via the soluble organic substance pipe 103 by the transport pump 13, and the ozone generated by the ozone generator 20 is also treated with the soluble organic substance ozone treatment. It is sent to the tank 16. In the soluble organic matter ozone treatment tank 16, ozone and the soluble organic matter are brought into contact with each other and reacted using an aeration-type second ozone injection method. This process is an example of the second ozone treatment according to the present invention, and the soluble organic matter ozone treatment tank 16 functions as a second ozone treatment unit that performs a second ozone treatment different from the first ozone treatment.

When ozone treatment is performed on a soluble organic substance, unlike the case where ozone treatment is performed on a solid component, the necessary ozone injection amount is not reduced even if the concentration of ozone in contact with the ozone is high. In addition, when the soluble organic substance is treated with ozone, the higher the concentration of ozone, the worse the reaction efficiency and the greater the amount of unreacted ozone. Here, the ozone injection amount is a value represented by the following formula (2), and a value obtained by multiplying the ozone concentration, the ozone flow rate, and the treatment time is used as the soluble organic substance concentration in the sludge-containing water and the treatment water amount (dissolution). Divided by the value obtained by multiplying the volume of the soluble organic substance in the organic organic ozone treatment tank 16).
Ozone injection amount [mgO ₃ / gCOD] = (ozone concentration [mgO ₃ / L] × ozone flow rate [L / min] × treatment time [min]) ÷ (soluble organic substance concentration of sludge-containing water [gCOD / L] × Treated water volume [L]) ... Formula (2)

  For the reasons described above, in the second ozone injection method, ozone having a low concentration is brought into contact with the soluble organic substance at a large ozone flow rate. As the ozone injection means in the second ozone injection method, for example, an ozone supply means such as an aeration type, an ejector type, a mechanical stirring type, and a downward injection type can be used. However, since it is necessary to efficiently react with a soluble organic substance even at a large gas flow rate, an aeration type or a downward injection type is preferable. By injecting low-concentration ozone with a large gas flow rate in a diffused manner, soluble organic substances can be efficiently decomposed with an ozone injection amount that is not excessive or insufficient.

  The ozone injected from the ozone generator 20 into the soluble organic matter ozone treatment tank 16 has a sufficiently low concentration of unreacted ozone generated when the soluble organic matter is decomposed in the soluble organic matter ozone treatment tank 16, and the reaction efficiency is high. If it is high, it is not particularly limited. However, when reaction efficiency is considered, 50 mg / L or more and 300 mg / L or less are preferable, and 100 mg / L or more and 200 mg / L or less are more preferable. The gas-liquid flow rate ratio in the soluble organic matter ozone treatment tank 16 (ozone flow rate / treatment water amount, hereinafter referred to as “G / L ratio 2”) is low-concentration ozone as long as the necessary ozone injection amount can be secured in a short time. Even if it exists, it is not specifically limited. However, when reaction efficiency is considered, 0.1 or more and 0.5 or less are preferable, and 0.2 or more and 0.3 or less are more preferable. This is because when the ozone concentration is smaller than the above range, or when the G / L ratio 2 is smaller than the above range, the ozone injection amount is small and the soluble organic matter in the sludge-containing treated water may not be sufficiently decomposed. On the other hand, when the ozone concentration is larger than the above range or the G / L ratio 2 is larger than the above range, the injected ozone does not react efficiently with the soluble organic matter, and unreacted ozone may be generated. It is.

  Although not shown in FIG. 1 in order to avoid complexity, the water treatment system according to the present embodiment has a soluble exhaust ozone pipe for exhausting unreacted ozone generated in the soluble organic ozone treatment tank 16. It is provided on the organic matter ozone treatment tank 16.

  The flow meter 22 detects bubbles 9 (slag flow or mist flow) in the soluble organic matter pipe 103. Therefore, when the flow meter 22 detects that the upper foam is sent to the soluble organic substance pipe 103, the return direction switching valve 15 is opened to the foam storage pipe 104 side, and the upper foam 9 is opened to the solid component-containing foam storage tank 17. Store in.

  After the ozone injection in the soluble organic matter ozone treatment tank 16 is completed, the foam pump 25 and the return pump 26 are activated. The return pump 26 sends the treated water after the treatment in the soluble organic matter ozone treatment tank 16 to the defoaming section 24. The foam pump 25 injects the foam 9 stored in the solid component-containing foam storage tank 17 into the treated water sent to the defoaming section 24 by the return pump 26. Dissolved ozone contained in the treated water sent by the return pump 26 reacts with the solid components contained in the foam 9 injected by the foam pump 25 and is consumed. The treated water in which dissolved ozone has been consumed by the reaction with the solid component contained in the bubbles 9 is returned to the aeration tank 1.

  The foam 9 stored in the solid component-containing foam storage tank 17 contains a solid component. Therefore, the ozone treatment using the first ozone injection method may be performed again by sending it to the mechanism portion located between the ejector 7 and the inflow portion 12 again.

  After the ozone injection in the soluble organic matter ozone treatment tank 16 is completed, the switching valve 21 connects the ozone supply pipe 109 and the first injection pipe 110. After the ozone supply pipe 109 and the first injection pipe 110 are connected, the ejector 7 starts again the ozone treatment of the sludge-containing water extracted from the aeration tank 1 using the first ozone injection method. In other words, all the steps described above, that is, the steps from the ozone treatment using the first ozone injection method via the ejector 7 to the ozone treatment again are repeated continuously for a predetermined time.

  The solid component in the foam 9 returned to the aeration tank 1 is efficiently modified into a readily decomposable substance by the ozone treatment using the first ozone injection method, and the biodegradability is enhanced. Therefore, it is biologically processed in the aeration tank 1 to become carbon dioxide gas, and a reduction in the amount of excess sludge is promoted. Further, the soluble organic matter returned to the aeration tank 1 is newly generated by using the soluble organic matter as a carbon source because the soluble organic matter is efficiently ozone-treated by the second ozone injection method by separation from the solid component. The amount of sludge to be reduced is led. Therefore, it is possible to supply an appropriate amount of ozone in consideration of not only the solid components of excess sludge but also soluble organic matter.

In the first ozone injection method, it is preferable to control the ozone generator 20 so that the ozone injection amount is 30 mgO ₃ / gSS or more and 100 mgO ₃ / gSS. In the second ozone injection method, it is preferable to control the ozone generator 20 so that it is 10 mgO ₃ / gCOD or more and 100 mgO ₃ / gCOD or less, and the ozone generator 20 is ₃₀ mgO ₃ / gCOD or more and 60 mgO ₃ / gCOD or less. It is more preferable to control. If it is in the above range, it is possible to efficiently decompose both solid components and soluble organic substances in sludge-containing treated water with an excess and shortage of ozone injection amount, and increase the amount of excess sludge reduction per ozone injection amount. .

  The step of extracting the sludge-containing treated water from the aeration tank 1 and returning the treated sludge-containing treated water to the aeration tank 1 is desirably performed periodically and intermittently. By periodically and intermittently performing the drawing / returning process, it is possible to suppress an increase in the organic matter decomposition load carried by the microorganisms in the aeration tank 1 without excessively reducing the amount of organic substances that are the substrate of microorganisms in the aeration tank 1. It is. That is, it is possible to prevent deterioration of treated water quality while suppressing a decrease in biological activity in the aeration tank 1.

  The interval between the drawing / returning steps performed periodically and intermittently may be set as appropriate according to the organic matter load of microorganisms in the aeration tank 1 and the amount of excess sludge generated, and is not particularly limited. However, considering the balance between maintaining biological activity and reducing excess sludge, it is preferably 1 hour to 24 hours, more preferably 2 hours to 12 hours, and even more preferably 4 hours to 6 hours. If the interval between the extraction and return processes performed periodically and intermittently is smaller than the above range, microorganisms contributing to wastewater treatment in the aeration tank 1 will also be extracted, so that the amount of microorganisms contributing to wastewater treatment is insufficient. This is because the microbial activity is reduced, and the wastewater treatment in the aeration tank 1 is not sufficiently performed, which may cause deterioration of water quality. On the other hand, if the interval between the withdrawal and return processes performed periodically and intermittently is larger than the above range, the microorganisms increased by consuming organic matter contained in the wastewater as a substrate rather than the amount of excess sludge reduced by the ozone treatment. This is because there is a possibility that the amount of growth of the sludge increases and the amount of excess sludge cannot be reduced as a whole.

  The “treated sludge ratio” is defined as a value obtained by dividing the amount of ozone-treated sludge per day by the amount of surplus sludge generated per day. In the water treatment system according to Embodiment 1, the treatment sludge ratio may be appropriately set according to the organic matter load of microorganisms in the aeration tank 1, the amount of surplus sludge generation, and the like. Although this process sludge ratio is not specifically limited, 0.5 or more and 5 or less are preferable, and 2 or more and 3 or less are more preferable. This is because when the treatment sludge ratio is less than 0.5, the amount of sludge reduction due to ozone injection is small, and the excess sludge amount may not be sufficiently reduced. This is because when the treatment sludge ratio exceeds 5, the amount of microorganisms in the aeration tank 1 is excessively reduced, the microorganism activity is lowered, and the quality of the treated water may be deteriorated. On the other hand, when the treatment sludge ratio is in the range of 2 or more and 3 or less, the excess sludge can be efficiently reduced while maintaining the microbial activity in the aeration tank 1.

  The operation of the water treatment system according to the first embodiment will be described. FIG. 2 is a flowchart showing a processing procedure of the control device 19.

  The control device 19 gives a command to the ozone generator 20 and the like, and a relatively small flow rate and high concentration ozone used in the first ozone injection method and a relatively low concentration and large flow rate ozone used in the second ozone treatment. And prepare.

  The control device 19 uses the first ozone injection method to treat the sludge-containing treated water extracted from the aeration tank 1 and a relatively small flow rate and high-concentration ozone in a mechanism portion located between the ejector 7 and the inflow portion 12. Command to react (step S1). The control device 19 issues a command to store the sludge-containing treated water that has been subjected to the first ozone treatment using the first ozone injection method in the storage tank 8 (step S2).

  The control device 19 instructs the circulation direction electromagnetic valve 14 and the circulation pump 13 and the like to draw a part of the sludge-containing treated water stored in the storage tank 8 from the lower side of the storage tank 8 using the extraction part 11 and circulate. The transportation process which flows into the upper side of the storage tank 8 through the pipe 102 is performed a plurality of times to circulate the sludge-containing treated water (step S3). During the circulation of the sludge-containing treated water, the control device 19 instructs the detection unit 18 to detect the physical properties of the sludge-containing treated water stored on the lower side of the storage tank 8. The detection unit 18 transmits an output signal indicating the detection result to the control device 19.

  The control device 19 determines whether or not the inside of the storage tank 8 is in a bubble trap state based on the output signal transmitted from the detection unit 18 (step S4). Specifically, the solid component of the sludge-containing treated water is sufficiently trapped in the bubbles 9 in the upper portion of the storage tank 8, and the soluble organic matter of the sludge-containing treated water is separated from the solid component and is moved downward in the storage tank 8. It is determined whether or not the existing bubble trap state is reached.

  When it is determined that the bubble trap state has not been reached (S4: NO), the control device 19 returns the processing procedure to step S3, further performs the transportation process, performs the first ozone treatment again, and circulates the sludge-containing treated water. And instructing the separation of the solid component and the soluble organic substance. When it is determined that the bubble trap state has been reached (S4: YES), the control device 19 instructs the circulation pump 13 and the like to cause the soluble organic matter existing below in the storage tank 8 to pass through the soluble organic matter pipe 103. It sends to the soluble organic matter ozone treatment tank 16, instructs the switching valve 21, etc., sends a relatively low concentration and large flow of ozone generated by the ozone generator 20 to the soluble organic matter ozone treatment tank 16, and the second ozone injection Using the method, the sludge-containing treated water and ozone are reacted in the ozone treatment tank 16 (step S5), and the treatment is terminated.

  According to the water treatment system according to the first embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank by the reaction between the solid component in the sludge-containing treated water and ozone, and the sludge is obtained. The soluble organic substance in the contained treated water can be separated to the lower side of the storage tank, and the separation state can be detected. Therefore, it is possible to supply an appropriate amount of ozone in consideration of not only the solid components of excess sludge but also soluble organic matter. By efficiently decomposing the soluble organic matter, it is possible to reduce the amount of excess sludge newly generated using the soluble organic matter as a carbon source.

  As described above, the water treatment system according to the first embodiment includes a mechanism that performs ozone treatment using a different ozone injection method at a timing when it is detected that an appropriate separation state has been reached. Therefore, a solid component can be efficiently decomposed with a small flow rate and high concentration of ozone, and a soluble organic substance from which the solid component has been separated can be efficiently decomposed with a large flow rate and low concentration of ozone. Therefore, the solid component and the soluble organic substance in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount suitable for each, and the amount of excess sludge reduction per ozone injection amount can be increased. That is, it is possible to supply an appropriate amount of ozone in consideration of not only the solid component of the excess sludge but also the soluble organic matter.

Embodiment 2. FIG.
A water treatment system according to Embodiment 2 of the present invention will be described. In the water treatment system according to the second embodiment, the basic configuration and operation are the same as those in the first embodiment, except that a continuous treatment pipe 114 is provided between the ejector 7 and the cutoff electromagnetic valve 23. Different.

  FIG. 3 is a schematic diagram showing a device configuration, a control system, a flow system, and the like of the water treatment system according to the second embodiment. In the figure, the same components and members as those of the water treatment system according to Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted unless particularly necessary.

  In the water treatment system according to the second embodiment, the continuous treatment pipe 114 is provided between the ejector 7 and the cutoff electromagnetic valve 23, and the cutoff electromagnetic valve 23 opens and closes for a predetermined time. Therefore, the aeration tank 1 and the storage tank 8 can be selected as the destinations of the sludge-containing treated water that has been extracted by the extraction pump 5 and contacted with ozone in the ejector 7. Specifically, when the shut-off solenoid valve 23 is closed, the sludge-containing treated water that has reacted with ozone in the ejector 7 is returned to the aeration tank 1 through the continuous treatment pipe 114, and the shut-off solenoid valve 23 is opened. In the state, the sludge-containing treated water that has reacted with ozone in the ejector 7 is sent to the storage tank 8 via the shut-off electromagnetic valve 23. The sludge-containing treated water sent to the storage tank 8 is returned to the aeration tank 1 after the ozone treatment in the storage tank 8.

  In the sludge-containing water returned to the aeration tank 1 through the continuous pipe 114, solid components are decomposed by the ozone in the ejector 7, but soluble organic substances generated by the decomposition of the solid components are promoted to be efficiently decomposed. Not. On the other hand, in the sludge-containing water returned to the aeration tank 1 through the storage tank 8, not only the solid components but also soluble organic substances are efficiently decomposed by ozone as described in the first embodiment.

  In the water treatment system according to Embodiment 2 having the above-described structure, preferential decomposition of solid components contained in sludge-containing water and efficient decomposition of both solid components and soluble organic matter components contained in sludge-containing water. And can be selected flexibly. Therefore, the amount of solid components and the amount of soluble organic matter contained in the aeration tank 1 can be adjusted, and the organic matter load of microorganisms in the aeration tank 1 can be maintained at an appropriate value. Therefore, deterioration of the quality of treated water can be suppressed more flexibly. Specifically, when the organic matter load of microorganisms in the aeration tank 1 is small, the shut-off electromagnetic valve 23 is closed, and the ratio of the sludge-containing water in which the solid components are decomposed preferentially to the aeration tank 1 is increased. In addition, the amount of undecomposed soluble organic matter returned to the aeration tank 1 can be increased, and the organic load in the aeration tank 1 can be increased. Moreover, when the organic substance load of the microorganisms in the aeration tank 1 is large, the ratio that the sludge containing water in which both the solid component and the soluble organic substance are efficiently decomposed is returned to the aeration tank 1 is increased. The amount of undecomposed dissolved organic matter returned to 1 can be reduced, and the organic matter load in the aeration tank 1 can be reduced.

  The ratio of the amount of sludge-containing water in which both the solid component and the soluble organic material are decomposed is preferably 10% or more, even if the organic matter load of the microorganisms in the aeration tank 1 is small, preferably 20% or more. Is more preferable. If it is smaller than the above range, the effect of the present invention cannot be sufficiently obtained, and the amount of surplus sludge newly generated in the aeration tank 1 by the undecomposed soluble organic matter may increase, and the surplus sludge may not be reduced sufficiently. Because there is.

  According to the water treatment system according to the second embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank 8 by the reaction between the solid component in the sludge-containing treated water and ozone, The soluble organic matter in the sludge-containing treated water can be separated to the lower side of the storage tank 8, and the separation state can be detected. Therefore, the soluble organic substance after separation can be efficiently decomposed by ozone. Accordingly, it is possible to reduce the amount of sludge newly generated using soluble organic substances as a carbon source. In addition, since it has a mechanism that uses an ozone injection method that efficiently decomposes soluble organic substances at the timing of detection of the bubble trap status, it efficiently decomposes solid components with a small flow rate and high concentration of ozone, resulting in a large flow rate and a low flow rate. Dissolved organic substances can be efficiently decomposed with ozone at a concentration. Therefore, both the solid component and the soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. In addition, by using the continuous pipe 114, both the sludge-containing water in which the solid component is preferentially decomposed and the solid component and the soluble organic component are efficiently decomposed according to the organic matter load of the microorganisms in the aeration tank 1. The ratio of sludge containing water can be changed. Therefore, the organic substance load of the microorganisms in the aeration tank 1 can be maintained at an appropriate value, and deterioration of treated water quality can be efficiently suppressed. That is, it is possible to supply an appropriate amount of ozone in consideration of not only the solid component of the excess sludge but also the soluble organic matter.

Embodiment 3 FIG.
A water treatment system according to Embodiment 3 of the present invention will be described. The basic structure and operation of the water treatment system according to the third embodiment are the same as those of the second embodiment, except that a sludge crushing ejector 27 is provided on the upstream side of the ejector 7.

  FIG. 4 is a schematic diagram showing a device configuration, a control system, a flow system, and the like of the water treatment system according to the third embodiment. In the figure, the same components and members as those of the water treatment system according to Embodiment 2 are denoted by the same reference numerals, and the description thereof is omitted unless particularly required.

  In the third embodiment, the sludge-containing water extracted by the extraction pump 5 is brought into contact with air in the sludge crushing ejector 27 as a process before the sludge-containing water extracted by the extraction pump 5 is brought into contact with ozone in the ejector 7. That is, the flow of the high-pressure sludge-containing water is depressurized by the nozzle portion of the sludge crushing ejector 27, and the reduced sludge-containing water comes into contact with the air. For this reason, solid components in sludge-containing water contain flocs in which microbial aggregates are in the form of cotton scraps of about a few millimeters, but the flocs are crushed and broken apart by physical impact when they come into contact with air. Become.

  In the excess sludge reduction process of the water treatment system having the above-described structure, when the sludge-containing water extracted by the extraction pump 5 comes into contact with ozone in the ejector 7, the floc formed containing solid components is already crushed. Will be. Therefore, compared with a flock-like solid component, the surface area of the solid component in contact with ozone is increased, and ozone and the solid component can be reacted more efficiently.

  According to the water treatment system according to the third embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank 8 by the reaction between the solid component in the sludge-containing treated water and ozone, The soluble organic matter in the sludge-containing treated water can be separated to the lower side of the storage tank 8, and the separation state can be detected. Therefore, the soluble organic substance after separation can be efficiently decomposed by ozone. Accordingly, it is possible to reduce the amount of sludge newly generated using soluble organic substances as a carbon source. In addition, since it has a mechanism that uses an ozone injection method that efficiently decomposes soluble organic substances at the timing of detection of the bubble trap status, it efficiently decomposes solid components with a small flow rate and high concentration of ozone, resulting in a large flow rate and a low flow rate. Dissolved organic substances can be efficiently decomposed with ozone at a concentration. Therefore, both the solid component and the soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. In addition, by using the continuous pipe 114, both the sludge-containing water in which the solid component is preferentially decomposed and the solid component and the soluble organic component are efficiently decomposed according to the organic matter load of the microorganisms in the aeration tank 1. The ratio of sludge containing water can be changed. Therefore, the organic substance load of the microorganisms in the aeration tank 1 can be maintained at an appropriate value, and deterioration of treated water quality can be efficiently suppressed. Moreover, before the solid component and ozone in sludge containing water react in the mechanism part located between the ejector 7 and the inflow part 12, the floc formed including the solid component is separated in the sludge crushing ejector 27, The surface area of the solid component that comes into contact with ozone can be increased. Therefore, ozone and a solid component can be reacted more efficiently. Therefore, the amount of excess sludge reduction per ozone injection amount can be further improved. That is, it is possible to supply an appropriate amount of ozone in consideration of not only the solid component of the excess sludge but also the soluble organic matter.

Embodiment 4 FIG.
A water treatment system according to Embodiment 4 of the present invention will be described. In the water treatment system according to the fourth embodiment, the basic configuration and operation are the same as in the third embodiment, but an ozone concentrator 28 is provided between the ozone generator 20 and the switching valve 21. The difference is that the ozone generator 20 and the ozone concentrator 28 are connected to the ozone supply pipe 109 via the oxygen gas return pipe 115.

  FIG. 5 is a schematic diagram illustrating a device configuration, a control system, a flow system, and the like of the water treatment system according to the fourth embodiment. In the figure, the same components and members as those of the water treatment system according to Embodiment 3 are denoted by the same reference numerals, and description thereof is omitted unless particularly required.

  The water treatment system according to Embodiment 4 includes an ozone concentrator 28 on the downstream side of the ozone generator 20. The ozone generated by the ozone generator 20 is concentrated by the ozone concentrator 28. The concentrated ozone is injected into the sludge-containing water through the ejector 7.

  The ozone concentrator 28 is a device that adsorbs and concentrates ozone generated by the ozone generator 20, and contains a material that can adsorb ozone. The material capable of adsorbing ozone is not particularly limited, and an adsorbent such as silica gel can be used.

  The ozone generator 20 is preferably operated at an ozone concentration of 150 mg / L or more and 310 mg / L, preferably 190 mg / L or more and 290 mg / L or less from the viewpoint of running cost. In the water treatment systems of Embodiments 1 to 3, it is difficult to supply ozone at a higher concentration. However, in the water treatment system according to the fourth embodiment, by providing the ozone concentrator 28, the ozone concentration can be concentrated to a maximum of 2000 mg / L, and the concentration of the supplied ozone can be increased.

  In the ozone concentrator 28, by controlling the temperature and pressure of the adsorption tower in which the adsorbent is stored, it is possible to form optimum adsorption conditions and optimum desorption conditions, and generate ozone with a desired concentration. Can be. Further, in the step of adsorbing and concentrating the ozone generated by the ozone generator 20 in the ozone concentrator 28, the oxygen gas which is a by-product that has not been adsorbed is returned to the ozone generator by the oxygen gas return pipe 115, whereby the ozone generator 20 can be reused as the raw material gas used in No. 20, and the running cost can be reduced.

  In the water treatment system according to the fourth embodiment, as described above, the ejector 7 generates ultra-high-concentration ozone exceeding the ozone concentration of 400 mg / L that can be generated by the ozone generator 20 shown in the first embodiment alone. It can be reacted with solid components in sludge-containing water. Therefore, ozone and a solid component can be reacted more efficiently. The ozone concentration obtained by the ozone concentrator 28 can be controlled by the amount of oxygen gas purged into the adsorption tower that has adsorbed ozone.

  In the first ozone injection method in which the solid component in the sludge-containing water and ozone are reacted in the ejector 7 to decompose the solid component, the amount of oxygen gas purged into the adsorption tower in which ozone is adsorbed is reduced. The excess sludge can be efficiently decomposed with the ozone injection amount without excess or deficiency by reacting the flow rate and ultra-high concentration ozone with the solid components in the sludge-containing water. When the separation state of the solid component and the soluble organic matter in the sludge-containing water is detected by the detection unit 18 and an output signal indicating the bubble trap state is sent to the control device 19, the soluble organic matter is obtained using the second ozone injection method. Ozone treatment is performed in the ozone treatment tank 16. In the second ozone injection method, by increasing the purge amount of the oxygen gas, in the soluble organic matter ozone treatment tank 16, a large flow rate and low concentration of ozone are reacted with the soluble organic matter in the sludge-containing water, and there is no excess or deficiency. Excess sludge can be efficiently decomposed by the amount of ozone injected.

  In the first ozone injection method, the concentration of ozone injected from the ozone concentrator 28 to the ejector 7 is not particularly limited as long as the solid components in the sludge-containing treated water can be efficiently decomposed. However, in consideration of the operation performance of the apparatus, 600 mg / L or more and 2000 mg / L or less is preferable, and 800 mg / L or more and 1500 mg / L or less is more preferable. In order to generate ozone exceeding an ozone concentration of 1500 mg / L, a lower temperature and low pressure environment is required. Therefore, it is difficult to control the ozone concentrator 28 at present, and the cost of the water treatment system may increase. obtain. Therefore, the upper limit of the ozone concentration is preferably 1500 mg / L.

  The G / L ratio 1 in the ejector 7 is not particularly limited as long as the solid components in the sludge-containing treated water can be sufficiently decomposed. However, the G / L ratio 1 is decreased in order to efficiently react the ultra-high concentration ozone generated by the ozone concentrator 28. It is necessary and 0.01 or more and 0.12 or less are preferable, and 0.04 or more and 0.1 or less are preferable. This is because when the G / L ratio 1 is smaller than the above range, the ozone injection amount is small and the solid components in the sludge-containing treated water may not be sufficiently decomposed. On the other hand, when the G / L ratio 1 is larger than the above range, the ultra-high concentration ozone does not efficiently react with the solid components in the sludge-containing treated water in the ejector 7, and unreacted ozone is generated, and excessive ozone injection It is because there is a possibility of inviting.

  In the second ozone injection method, the concentration of ozone injected from the ozone concentrator 28 into the soluble organic matter ozone treatment tank 16 is the unreacted ozone generated when the soluble organic matter is decomposed in the soluble organic matter ozone treatment tank 16. Although it will not specifically limit if a density | concentration is low enough and reaction efficiency is high, 50 mg / L or more and 300 mg / L or less are preferable, and 100 mg / L or more and 200 mg / L or less are more preferable. Further, the G / L ratio 2 is not particularly limited as long as a necessary ozone injection amount can be secured in a short time even in a low concentration ozone, but is preferably 0.1 or more and 0.5 or less, preferably 0.2 or more and 0.3. The following is more preferable. When the ozone concentration is larger than the above range, or when the G / L ratio 2 is larger than the above range, the injected ozone does not react efficiently with the soluble organic matter, and unreacted ozone may be generated. is there. On the other hand, when the ozone concentration is smaller than the above range, or when the G / L ratio 2 is smaller than the above range, the ozone injection amount may be insufficient, and the soluble organic matter in the sludge-containing treated water may not be sufficiently decomposed. Because.

In the first ozone injection method, it is preferable to control the ozone concentrator 28 to the ozone injection rate becomes 15mgO ₃ / gSS more 50mgO ₃ / _gSS, in the second ozone injection method, 10mgO ₃ / gCOD more 100mgO ₃ / It is preferable to control the ozone concentrator 28 so as to be not more than gCOD, and it is more preferable to control the ozone concentrator 28 so as to be not less than 30 mgO ₃ / gCOD and not more than 60 mgO ₃ / gCOD. Within the above range, both solid components and soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. Because.

  According to the water treatment system according to the fourth embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank 8 by the reaction between the solid component in the sludge-containing treated water and ozone, The soluble organic matter in the sludge-containing treated water can be separated to the lower side of the storage tank 8, and the separation state can be detected. Therefore, the soluble organic substance after separation can be efficiently decomposed by ozone. Accordingly, it is possible to reduce the amount of sludge newly generated using soluble organic substances as a carbon source. In addition, since it has a mechanism that uses an ozone injection method that efficiently decomposes soluble organic substances at the timing of detection of the bubble trap status, it efficiently decomposes solid components with a small flow rate and high concentration of ozone, resulting in a large flow rate and a low flow rate. Dissolved organic substances can be efficiently decomposed with ozone at a concentration. Therefore, both the solid component and the soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. In addition, by using the continuous pipe 114, both the sludge-containing water in which the solid component is preferentially decomposed and the solid component and the soluble organic component are efficiently decomposed according to the organic matter load of the microorganisms in the aeration tank 1. The ratio of sludge containing water can be changed. Therefore, the organic substance load of the microorganisms in the aeration tank 1 can be maintained at an appropriate value, and deterioration of treated water quality can be efficiently suppressed. Moreover, before the solid component and ozone in sludge containing water react in the mechanism part located between the ejector 7 and the inflow part 12, the floc formed including the solid component is separated in the sludge crushing ejector 27, The surface area of the solid component that comes into contact with ozone can be increased. Therefore, ozone and a solid component can be reacted more efficiently. In addition, by providing the ozone concentrator 28, it is possible to react an ultra-high concentration ozone exceeding the ozone concentration of 400 mg / L that can be generated by the ozone generator 20 alone with a solid component in the sludge-containing water. Therefore, ozone and a solid component can be reacted more efficiently. Therefore, the amount of excess sludge reduction per ozone injection amount can be further increased. That is, it is possible to supply an appropriate amount of ozone in consideration of not only solid components of excess sludge but also soluble organic matter.

Embodiment 5. FIG.
A water treatment system according to Embodiment 5 of the present invention will be described. In the water treatment system according to the fifth embodiment, the basic configuration and operation are the same as those in the fourth embodiment, except that the cooling unit 202 is omitted, and the post-treatment unit 201 and the ozone generator are different. 20 is connected.

  FIG. 6 is a schematic diagram showing a device configuration, a control system, a flow system, and the like of the water treatment system according to the fifth embodiment. In the figure, the same components and members as those of the water treatment system according to Embodiment 4 are denoted by the same reference numerals, and description thereof is omitted unless particularly required.

  In the water treatment systems of Embodiments 1 to 4, the ozone generator 20 is configured to be cooled by the cooling unit 202. However, in the water treatment system of the fifth embodiment, the ozone generator 20 is cooled by the biologically treated water 6 that has flowed out of the post-treatment unit 201. The post-processing unit 201 and the ozone generator 20 are connected via a transport pump (not shown).

  In the surplus sludge reduction process in the water treatment systems of Embodiments 1 to 4, the cooling unit 202 such as a chiller using a heat exchange type cooler or tap water is provided. However, in the excessive sludge reduction process in the water treatment system of the fifth embodiment, such a cooling unit 202 is not necessary. Therefore, additional costs such as the initial cost, power cost, and water bill of the equipment can be reduced, which is economical. The water quality that can be used for cooling the ozone generator 20 is at least not extremely high in pH, not extremely low, and does not have a high residual chlorine concentration, so long as it does not corrode the welded parts of the component equipment.

  According to the water treatment system according to the fifth embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank 8 by the reaction between the solid component in the sludge-containing treated water and ozone, The soluble organic matter in the sludge-containing treated water can be separated to the lower side of the storage tank 8, and the separation state can be detected. Therefore, after separation, soluble organic matter can be selectively decomposed with ozone. Accordingly, it is possible to reduce the amount of sludge newly generated using soluble organic substances as a carbon source. In addition, since it has a mechanism that uses an ozone injection method that efficiently decomposes soluble organic substances at the timing of detection of the bubble trap status, it efficiently decomposes solid components with a small flow rate and high concentration of ozone, resulting in a large flow rate and a low flow rate. Dissolved organic substances can be efficiently decomposed with ozone at a concentration. Therefore, both the solid component and the soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. In addition, by using the continuous pipe 114, both the sludge-containing water in which the solid component is preferentially decomposed and the solid component and the soluble organic component are efficiently decomposed according to the organic matter load of the microorganisms in the aeration tank 1. The ratio of sludge containing water can be changed. Therefore, the organic substance load of the microorganisms in the aeration tank 1 can be maintained at an appropriate value, and deterioration of treated water quality can be efficiently suppressed. Moreover, before the solid component and ozone in sludge containing water react in the mechanism part located between the ejector 7 and the inflow part 12, the floc formed including the solid component is separated in the sludge crushing ejector 27, The surface area of the solid component that comes into contact with ozone can be increased. Therefore, ozone and a solid component can be reacted more efficiently. In addition, by providing the ozone concentrator 28, it is possible to react an ultra-high concentration ozone exceeding the ozone concentration of 400 mg / L that can be generated by the ozone generator 20 alone with a solid component in the sludge-containing water. Therefore, ozone and a solid component can be reacted more efficiently. Therefore, the amount of excess sludge reduction per ozone injection amount can be further increased. Moreover, since the treated water that has flowed out of the aeration tank 1 and separated by the post-treatment unit 201 is used for cooling the ozone generator 20, it is economical. In other words, it is possible to more economically supply an appropriate amount of ozone in consideration of not only the solid components of excess sludge but also soluble organic matter.

Embodiment 6 FIG.
A water treatment system according to Embodiment 6 of the present invention will be described. The water treatment system according to the sixth embodiment has the same basic configuration and operation as those of the fifth embodiment, except that the post-treatment unit 201 is deleted, and a membrane module is provided in the aeration tank 1. The difference is that 203 and the membrane module air diffuser 29 are provided, and the membrane surface cleaning blower 30 is provided outside the aeration tank 1.

  FIG. 7 is a schematic diagram illustrating a device configuration, a control system, a flow system, and the like of the water treatment system according to the sixth embodiment. In the figure, the same components and members as those of the water treatment system according to Embodiment 5 are denoted by the same reference numerals, and description thereof is omitted unless particularly required.

  In the water treatment system of the sixth embodiment, the membrane module 203, the membrane module air diffuser 29, and the membrane surface cleaning blower 30 are used to treat the wastewater 4 such as sewerage and factory wastewater by the membrane separation activated sludge method (MBR). Equipped with a membrane separation activated sludge treatment mechanism.

  The kind of the filtration membrane which comprises the membrane module 203 is not specifically limited, Various filtration membranes well-known in the said technical field, such as a microfiltration (MF) membrane and an ultrafiltration (UF) membrane, can be used.

  Although the average pore diameter of the filtration membrane which comprises the membrane module 203 is not specifically limited, 0.001 micrometer-1 micrometer are preferable and 0.01 micrometer-0.8 micrometer are more preferable. The shape of the filtration membrane is not particularly limited, and may be a shape known in the technical field such as a hollow fiber or a flat membrane. In addition, the membrane module 203 can employ an immersion type, a casing type, a monolith type, and the like. Further, the filtration method of the membrane module 203 can be either a whole amount filtration method or a cross flow filtration method.

  In the excess sludge reduction process in the water treatment system of the sixth embodiment, the activated sludge having an MLSS (activated sludge suspended matter) concentration of 3000 to 20000 mg / L is filled in the aeration tank 1. When waste water 4 such as sewer and factory wastewater is supplied into the aeration tank 1, biological treatment using activated sludge is performed in the aeration tank 1. Biologically treated water 6 (filtered water) can be obtained by performing a filtration treatment using the membrane module 203 after the biological treatment. Since the membrane surface cleaning blower 30 is connected to the membrane module air diffuser 29 and air is supplied from the membrane module air diffuser 29 to the membrane module 203, the membrane surface flow of activated sludge in the aeration tank 1 occurs. In addition, the filtration process by the membrane module 203 can be performed stably.

  The filtration process using the membrane module 203 may be performed continuously. Moreover, you may stop for a fixed time at the timing which returns the sludge containing treated water which carried out ozone treatment to the aeration tank 1. FIG. When the filtration treatment is stopped at the timing when the treated sludge-containing water treated with ozone is returned to the aeration tank 1, it is possible to further suppress the deterioration of the water quality of the biological treatment water 6 depending on the increase in organic matter load of microorganisms in the aeration tank 1. it can.

  In the sixth embodiment, the case where the membrane module 203 is immersed in one aeration tank 1 is illustrated. However, the aeration tank 1 may be divided into two or more and the membrane module 203 may be immersed in the aeration tank 1 on the downstream side. Alternatively, the casing membrane module 203 may be provided outside the aeration tank 1, and filtration may be performed while transporting activated sludge between the casing membrane module 203 and the aeration tank 1. In any case, the configuration of the water treatment system according to Embodiment 6 can be modified within a range that does not impair the effects of the present invention.

  According to the water treatment system according to the sixth embodiment, as described above, the solid component is trapped in the foam 9 generated on the upper side of the storage tank 8 by the reaction between the solid component in the sludge-containing treated water and ozone, The soluble organic matter in the sludge-containing treated water can be separated to the lower side of the storage tank 8, and the separation state can be detected. Therefore, after separation, soluble organic matter can be selectively decomposed with ozone. Accordingly, it is possible to reduce the amount of sludge newly generated using soluble organic substances as a carbon source. In addition, since it has a mechanism that uses an ozone injection method that efficiently decomposes soluble organic substances at the timing of detection of the bubble trap status, it efficiently decomposes solid components with a small flow rate and high concentration of ozone, resulting in a large flow rate and a low flow rate. Dissolved organic substances can be efficiently decomposed with ozone at a concentration. Therefore, both the solid component and the soluble organic matter in the sludge-containing treated water can be efficiently decomposed with an ozone injection amount that is not excessive and insufficient, and the amount of excess sludge reduction per ozone injection amount can be increased. In addition, by using the continuous pipe 114, both the sludge-containing water in which the solid component is preferentially decomposed and the solid component and the soluble organic component are efficiently decomposed according to the organic matter load of the microorganisms in the aeration tank 1. The ratio of sludge containing water can be changed. Therefore, the organic substance load of the microorganisms in the aeration tank 1 can be maintained at an appropriate value, and deterioration of treated water quality can be efficiently suppressed. Moreover, before the solid component and ozone in sludge containing water react in the mechanism part located between the ejector 7 and the inflow part 12, the floc formed including the solid component is separated in the sludge crushing ejector 27, The surface area of the solid component that comes into contact with ozone can be increased. Therefore, ozone and a solid component can be reacted more efficiently. In addition, by providing the ozone concentrator 28, it is possible to react an ultra-high concentration ozone exceeding the ozone concentration of 400 mg / L that can be generated by the ozone generator 20 alone with a solid component in the sludge-containing water. Therefore, ozone and a solid component can be reacted more efficiently. Therefore, the amount of excess sludge reduction per ozone injection amount can be further increased. Moreover, since the treated water that has flowed out of the aeration tank 1 and separated by the post-treatment unit 201 is used for cooling the ozone generator 20, it is economical. Moreover, since the membrane separation activated sludge treatment mechanism is further provided, the quality of the treated water obtained after the treatment is further improved. In other words, considering not only the solid components of excess sludge but also soluble organic matter, it is possible to more economically supply an appropriate amount of ozone and obtain treated water with improved water quality.

  The invention is not limited to the specific details and exemplary embodiments described and described above. Variations and effects that can be easily derived by those skilled in the art are also included in the invention. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Aeration tank, 2 Aeration apparatus, 3 Air supply apparatus, 4 Waste water, 5 Extraction pump, 6 Biologically treated water, 7 Ejector, 8 Storage tank, 9 Foam, 10 Sludge containing treated water, 11 Extraction part, 12 Inflow part, DESCRIPTION OF SYMBOLS 13 Transport pump, 14 Transport direction solenoid valve, 15 Return direction switching valve, 16 Soluble organic matter ozone treatment tank, 17 Solid component containing foam storage tank, 18 Detection part, 19 Control apparatus, 20 Ozone generator, 21 Switching valve, 22 Flow meter, 23 shut-off solenoid valve, 24 defoaming part, 25 foam pump, 26 return pump, 27 sludge crushing ejector, 28 ozone concentrator, 29 membrane module air diffuser, 30 membrane surface cleaning blower, 101 extraction piping, 102 Transport piping, 103 Soluble organic piping, 104 Foam storage piping, 105 Foam piping, 106 Return piping, 107 Detection piping, 1 8 Detection section output line, 109 Ozone supply pipe, 110 First injection pipe, 111 Second injection pipe, 112 Exhaust ozone pipe, 113 Cooling pipe, 114 Continuous processing pipe, 115 Oxygen gas return pipe, 201 Post-processing section, 202 Cooling Part, 203 membrane module.

Claims (17)

In the water treatment system for decomposing the sludge-containing treated water by contacting ozone with the sludge-containing treated water in the aeration tank into which the water to be treated has flowed,
A first ozone treatment unit that performs a first ozone treatment on the sludge-containing treated water drawn from the aeration tank;
A storage tank for storing the sludge-containing treated water subjected to the first ozone treatment;
A transport unit that performs a plurality of transport processes in which a part of the sludge-containing treated water stored in the storage tank is extracted from the lower side of the storage tank and flows into the upper side of the storage tank;
The sludge containing treated water withdrawn from the lower side of the storage tank after performing the transport treatment a plurality of times includes a second ozone treatment unit that performs a second ozone treatment different from the first ozone treatment. And water treatment system. 2. The water treatment system according to claim 1, wherein the first ozone treatment uses high-concentration ozone at a smaller flow rate than the second ozone treatment. A detection unit for detecting physical properties of the sludge-containing treated water stored on the lower side;
The water treatment system according to claim 1 or 2, wherein the second ozone treatment unit performs the second ozone treatment based on a detection result of the detection unit. Continuous treatment piping for returning the sludge-containing treated water subjected to the first ozone treatment to the aeration tank;
A return piping for returning the sludge-containing treated water subjected to the second ozone treatment to the aeration tank;
The water treatment system according to any one of claims 1 to 3, further comprising a shut-off electromagnetic valve connected to the first ozone treatment unit, the continuous treatment pipe, and the storage tank. A sludge crushing ejector for reducing the sludge-containing treated water extracted from the aeration tank and bringing it into contact with air, and sending the sludge-containing treated water brought into contact with the air to the first ozone treatment unit; The water treatment system according to any one of claims 1 to 4. An ozone generator for generating first ozone used for the first ozone treatment and second ozone used for the second ozone treatment;
The water treatment system according to claim 1, further comprising an ozone concentrator that supplies the first ozone treatment unit with the concentrated ozone obtained by concentrating the first ozone. The water treatment system according to claim 6, wherein the concentration of the concentrated ozone is 800 mg / L to 1500 mg / L. The water treatment according to claim 6 or 7, wherein the ozone concentrator makes an oxygen gas purge amount when generating the first ozone smaller than an oxygen gas purge amount when generating the second ozone. system. After being returned by the return pipe, further comprising a post-treatment section for separating biological treatment water from the sludge-containing treatment water in the aeration tank,
The water treatment system according to any one of claims 6 to 8, wherein the post-treatment unit is connected to the ozone generation unit. In the water treatment method of decomposing the sludge-containing treated water by contacting ozone with the sludge-containing treated water in the aeration tank into which the water to be treated has flowed,
A first ozone treatment step of performing a first ozone treatment on the sludge-containing treated water extracted from the aeration tank;
A storage step of storing the sludge-containing treated water subjected to the first ozone treatment in a storage tank;
A transportation step of performing a plurality of transportation treatments in which a part of the sludge-containing treated water stored in the storage tank is extracted from the lower side of the storage tank and flows into the upper side of the storage tank;
A second ozone treatment step of performing a second ozone treatment different from the first ozone treatment on the sludge-containing treated water extracted from the lower side of the storage tank after performing the transport treatment a plurality of times. Water treatment method. 11. The water treatment method according to claim 10, wherein high-concentration ozone is prepared at a smaller flow rate than ozone used in the second ozone treatment as ozone used in the first ozone treatment. A detection step of detecting physical properties of the sludge-containing treated water stored on the lower side;
The water treatment method according to claim 10 or 11, wherein the second ozone treatment is performed based on a detection result of the detection step. A continuous treatment step of returning the sludge-containing treated water subjected to the first ozone treatment to the aeration tank;
A return process for returning the sludge-containing treated water subjected to the second ozone treatment to the aeration tank;
The water treatment method according to any one of claims 10 to 12, further comprising a changing step of changing a ratio between the continuous treatment step and the return step. Further comprising a contact step of reducing the sludge-containing treated water extracted from the aeration tank and bringing it into contact with air;
The water treatment method according to any one of claims 10 to 13, wherein the sludge-containing treated water brought into contact with the air is used for the first ozone treatment. An ozone generation step of generating first ozone used for the first ozone treatment and second ozone used for the second ozone treatment;
The water treatment method according to any one of claims 10 to 14, wherein the concentrated ozone obtained by concentrating the first ozone with an ozone concentrator is used for the first ozone treatment. The water treatment method according to claim 15, further comprising a concentrated ozone concentration setting step of setting the concentration of the concentrated ozone from 800 mg / L to 1500 mg / L. An oxygen gas purge amount setting step of setting an oxygen gas purge amount of the ozone concentrator when generating the first ozone to be smaller than an oxygen gas purge amount of the ozone concentrator when generating the second ozone. The water treatment method according to claim 15 or 16, characterized in that

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