Treatment facility for discharged sludge and treatment method therefor

Abstract

The present invention comprises: a first step in which discharged sludge containing organic sludge is placed in an aeration tank 13, and a wood powder having a particle diameter of 1 mm or less and capable of carrying aerobic bacteria that decompose the organic sludge and an enzyme that accelerates the decomposition of the organic sludge is also supplied to the aeration tank 13 and the mixture is aerated to perform aerobic bacteria treatment; a second step in which the discharged sludge that has been treated in the first step is placed in a sedimentation tank 17 to be separated into a sediment and treated water; and a third step in which the sediment generated in the second step is placed in a regeneration tank 18 to perform aeration treatment, wherein, when the treated material that has been treated in the third step is supplied to the aeration tank 13 and the wood powder is circulated and used, on condition that the chemical oxygen demand in the treated water that has been generated in the second step will exceed the concentration at which the treated water can be discharged to the outside of the system in the future, a liquid subjected to advanced treatment is supplied to a concentration adjustment tank 19 that has received the treated water, the liquid having the chemical oxygen demand reduced and being separated and recovered from the treated material in the regeneration tank 18 by a membrane separation means 39 provided to the regeneration tank 18, and the chemical oxygen demand in the treated water is thereby adjusted to be at most a concentration at which the treated water can be discharged to the outside of the system.

Description

Sludge wastewater treatment equipment and treatment method

[0001] The present invention relates to the treatment of sludge wastewater (including sewage) with a high BOD (biochemical oxygen demand), and more particularly to a sludge wastewater treatment facility and treatment method using an aeration tank in which enzymes are used.

[0002] Conventionally, various treatment facilities and methods have been proposed for sludge wastewater containing organic sludge discharged from ordinary homes, office buildings, various factories, etc. Specifically, there are activated sludge treatment methods using microorganisms and enzyme activation treatment methods using enzymes (see, for example, Patent Documents 1 and 2).

[0003] Patent No. 5925023 Patent No. 6685060

[0004] In the activated sludge treatment method using microorganisms (standard activated sludge treatment method), it was difficult to produce treated water of a stable concentration (a BOD concentration below which the water can be discharged) due to fluctuations in BOD (concentration fluctuations) in the sludge wastewater (raw water) being treated and climate change. On the other hand, in the enzyme activation treatment method using enzymes, although it is less susceptible to fluctuations in BOD in the sludge wastewater being treated and climate change, there was some impact on the production of treated water of a stable concentration, and there was room for further improvement.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a sludge wastewater treatment facility and a treatment method therefor that can treat sludge wastewater containing organic sludge more stably than conventional facilities, to the extent that the sludge wastewater can be discharged into rivers or the sea.

[0006] A sludge wastewater treatment facility according to the present invention that meets the above-mentioned objectives comprises an aeration tank that receives sludge wastewater containing organic sludge and aerates the sludge wastewater, a settling tank that receives the sludge wastewater aerated in the aeration tank and separates the sludge wastewater into sediment and treated water, a regeneration tank that receives the sediment accumulated in the settling tank and further aerates the sediment, and a circulation path that supplies the treated material from the regeneration tank to the aeration tank, wherein: the aeration tank uses wood powder with a particle size of 1 mm or less as a support for enzymes that promote the decomposition of the organic sludge and aerobic bacteria that decompose the organic sludge; downstream of the settling tank, a concentration adjustment tank is installed that receives the treated water separated in the settling tank and adjusts the chemical oxygen demand of the treated water to a concentration below which it can be discharged outside the system; the regeneration tank is installed with membrane separation means for separating and recovering advanced treatment liquid with reduced chemical oxygen demand from the treated material in the regeneration tank; The advanced treatment solution separated and recovered by the membrane separation means is supplied to the concentration adjustment tank on the condition that the chemical oxygen demand of the treated water in the concentration adjustment tank will exceed the concentration at which it can be discharged outside the system in the future. Here, the wood powder can contain the enzyme.

[0007] It is possible to supply new wood powder to the aeration tank to make up for any shortage of the recycled wood powder supplied to the aeration tank.

[0008] A method for treating sludge wastewater according to the present invention, which is aimed at the above-mentioned object, comprises: a first step of introducing sludge wastewater containing organic sludge into an aeration tank, and supplying wood powder having a particle size of 1 mm or less, capable of supporting enzymes that promote the decomposition of the organic sludge and aerobic bacteria that decompose the organic sludge, to the aeration tank and aerating the tank for aerobic bacterial treatment; a second step of introducing the sludge wastewater treated in the first step into a settling tank and separating it into a sediment and treated water; and a third step of introducing the sediment produced in the second step into a regeneration tank and aerating the sediment. When the treated product produced in the third step is supplied to the aeration tank and the wood powder is recycled, an advanced treatment liquid with reduced chemical oxygen demand, which has been separated and recovered from the treated product in the regeneration tank by a membrane separation means provided in the regeneration tank, is supplied to a concentration adjustment tank that has received the treated water, on the condition that the chemical oxygen demand of the treated water generated in the second step will exceed a concentration that can be discharged outside the system in the future, thereby adjusting the chemical oxygen demand of the treated water in the concentration adjustment tank to a concentration that can be discharged outside the system or below. Here, the wood powder may contain the enzyme.

[0009] When the amount of recycled wood powder supplied to the aeration tank is insufficient, new wood powder can be supplied to the aeration tank.

[0010] The sludge wastewater treatment system and method of the present invention employ an enzyme activation treatment method in an aeration tank, using enzymes that promote the decomposition of organic sludge and wood powder with a particle size of 1 mm or less as a support for aerobic bacteria that decompose the organic sludge. Here, provided that the chemical oxygen demand of the treated water generated in the settling tank exceeds the concentration at which it can be discharged, a concentration adjustment tank receives the treated water and supplies it with a highly treated solution with reduced chemical oxygen demand, separated and recovered from the treated material in the regeneration tank by a membrane separation device installed in the regeneration tank, to adjust the chemical oxygen demand of the treated water in the concentration adjustment tank to a concentration at which it can be discharged. In this way, the combination of the enzyme activation treatment method and the membrane separation device enables more stable treatment of sludge wastewater containing organic sludge to a level suitable for discharge into rivers or the sea. Furthermore, the use of the enzyme activation treatment method reduces the amount of sludge (sediment and treated material) generated during treatment by, for example, about half or more compared to the activated sludge treatment method, thereby significantly reducing adverse effects on the membrane separation device. This allows, for example, downsizing of the membrane separation means and reduction of costs required for replacement and cleaning.

[0011] 1 is an explanatory diagram of a sludge wastewater treatment facility and a treatment method thereof according to an embodiment of the present invention.

[0012] Next, with reference to the accompanying drawings, a description will be given of an embodiment of the present invention to facilitate understanding of the present invention. As shown in FIG. 1, a sludge wastewater treatment system 10 according to one embodiment of the present invention includes a raw water tank 11, a flow rate adjustment tank 12, first to third aeration tanks 13-15, a carrier tank 16, a settling tank 17, a regeneration tank 18, a concentration adjustment tank 19, a discharge tank 20, a sludge storage tank 21, and a circulation path 22. This system is capable of treating sludge wastewater containing organic matter more stably than conventional systems, to the extent that it can be discharged into a river or the sea. The dashed-dotted lines in the raw water tank 11, the flow rate adjustment tank 12, the regeneration tank 18, the discharge tank 20, and the sludge storage tank 21 indicate the lower limit of the liquid level in each tank. A detailed description will be provided below.

[0013] The raw water tank 11 is a tank that receives sludge wastewater (also simply referred to as "wastewater" or "raw water") to be treated, which contains organic sludge. The sludge wastewater has an activated sludge suspended solids concentration (MLSS) of, for example, 3000 to 6000 mg / L. The raw water tank 11 is provided with an aeration means 24 that sprays compressed air sent from an aeration blower 23, enabling the sludge wastewater inside to be agitated.

[0014] The sludge wastewater that has been agitated in the raw water tank 11 is supplied to the flow rate adjustment tank 12 via a screen means 25. The screen means 25 has a mesh with an opening (opening) of, for example, 1 mm (or may be about 1 to 10 mm) and removes debris larger than 1 mm from the wastewater pumped up from the raw water tank 11 by a pump 26. The opening of the screen means can be changed in various ways depending on the size of the debris contained in the sludge wastewater to be treated.

[0015] The flow rate adjustment tank 12 is a tank that stores sludge wastewater from which garbage has been removed by the screening means 25. The flow rate adjustment tank 12 is provided with an aeration means 27 that sprays compressed air sent from an aeration blower 23, and is configured to agitate the sludge wastewater treated by the screening means 25. The sludge wastewater stored in the flow rate adjustment tank 12 is pumped up by a pump 28 and supplied to the first aeration tank 13 via a raw water transfer adjustment means 29. The raw water transfer adjustment means 29 is a device that can control the amount of wastewater passing through to a constant amount and return excess wastewater to the flow rate adjustment tank 12. For example, the metering tank described in Patent Document 1 can be used, but there is no particular limitation as long as it is configured to adjust the amount of sludge wastewater supplied.

[0016] The first to third aeration tanks 13 to 15 are arranged in series and are tanks for aerating the sludge wastewater received from the flow rate adjustment tank 12. The first to third aeration tanks 13 to 15 can be continuously operated by constantly introducing small amounts of sludge wastewater into them while adjusting the flow rate with a raw water transfer adjustment means 29. In this case, sludge wastewater overflowing from the first aeration tank 13 flows into the second aeration tank 14, and further sludge wastewater overflowing from the second aeration tank 14 flows into the third aeration tank 15. The sludge wastewater overflowing from the third aeration tank 15 flows into the carrier tank 16 due to the difference in head. The first to third aeration tanks 13 to 15 are each provided with aeration means 30 to 32 that spray compressed air supplied from an aeration blower 23. Air (oxygen) is sent to the sludge wastewater containing organic matter supplied inside the tank, and the inside of the tank is stirred (i.e., aeration treatment). The organic matter contained in the wastewater is consumed and decomposed by aerobic bacteria (an example of aerobic bacteria), which are microorganisms contained in the wastewater (i.e., aerobic bacteria treatment).

[0017] Enzymes are supplied to the first aeration tank 13 (or the second aeration tank 14 or the second and third aeration tanks 14 and 15). The enzymes digest organic matter contained in the sludge wastewater into low-molecular-weight compounds and promote the decomposition of the organic matter by aerobic bacteria. While the treatment of sludge wastewater (decomposition of organic matter) by aerobic bacteria takes time, adding enzymes breaks down the organic matter into low-molecular-weight compounds, making them easier to decompose by aerobic bacteria. This further promotes the activity of the aerobic bacteria and shortens the treatment time. These aerobic bacteria also produce enzymes through their activity, which aid in the decomposition of organic sludge. Some of the enzymes remain in the treated water. An enzyme supplying means for supplying enzymes may be provided to one or more of the first to third aeration tanks 13 to 15.

[0018] In this example, three aeration tanks are arranged in series, enabling more complete organic matter decomposition by aerobic bacteria. However, depending on the amount of sludge wastewater to be treated, the concentration of suspended solids in the activated sludge, the size (volume) of the aeration tank, and other factors, a single tank, two tanks, or even four or more tanks may be arranged in series, or two or more aeration tanks may be arranged in parallel. Examples of enzymes include oil-decomposing enzymes (e.g., lipase), protein-decomposing enzymes (e.g., protease), starch-decomposing enzymes (e.g., amylase), plant fiber-decomposing enzymes (e.g., pectinase), and polysaccharide-decomposing enzymes (hemicellulase). Preferably, one or more of these enzymes are used as the main component. The amount of enzyme used is preferably, for example, about 1 / 100,000 to 1 / 10,000 of the wastewater volume, but is not particularly limited thereto. The amount can be varied depending on, for example, the concentration of suspended solids in the activated sludge and the BOD (BOD value) of the wastewater when it is discharged into a river or the sea.

[0019] The first aeration tank 13 (or any one or more of the first to third aeration tanks 13 to 15) is provided with a wood powder addition means 33 for supplying wood powder. The wood powder supports the aerobic bacteria contained in the sludge wastewater (provides a habitat (support) for the aerobic bacteria) and is resistant to decay by the aerobic bacteria. Here, "resistance" refers to the property that the rate at which the wood powder is decomposed by the aerobic bacteria is slower than the rate at which the organic matter in the sludge wastewater is decomposed. Examples of wood powder with such resistance include cedar, cypress, Japanese cypress, larch, Japanese cedar, Japanese red cedar, Douglas fir, zelkova, sawtooth oak, chestnut, teak, pinkado, merbau, and ipe. One or more of these can be used, but cedar is particularly preferred. It is preferable to use wood powder containing the enzymes described above (e.g., impregnated with enzymes).

[0020] The size of the wood powder may be small enough to sink without floating when added to water. Depending on the type of wood, the size should be about 1 mm or less (preferably 0.5 mm or less, more preferably 0.2 mm or less). While the lower limit is not particularly limited, for example, a size of about 0.01 mm (preferably 0.03 mm) with an average particle size of 0.1 mm to 0.6 mm (preferably 0.3 mm or less) can be used. By using wood powder of 1 mm or less that sinks without floating when added to water, it is possible to easily mix it with organic sludge. Wood powder may contain particles larger than 1 mm. The wood powder is preferably added to wastewater by first adding it to water and stirring it to absorb moisture, but it can also be added directly to sludge wastewater. For example, when adding 1 m3 of sludge wastewater with a BOD of about 1000 mg / L, the wood powder may be added to the wastewater in the form of a powder. ３ Approximately 50 to 100 L of water mixed with wood powder (wood powder concentration: for example, approximately 1 to 20% by mass, with a lower limit of approximately 3% by mass and an upper limit of approximately 15% by mass) can be supplied to the reactor, but this is not particularly limited and can be changed depending on, for example, the activated sludge suspended solids concentration and BOD when the activated sludge is discharged into a river or the sea.

[0021] The carrier tank 16 is a tank where a large number of carriers (e.g., porous materials such as sponges) with a particle size of approximately 5 to 20 mm, carrying a large number of aerobic bacteria (an example of microorganisms), are introduced and used to aerobically treat the sludge wastewater aerated in the first to third aeration tanks 13 to 15. In this case, too, the sludge wastewater contains enzymes, and these enzymes and aerobic bacteria work together to purify the treated water. The carrier tank 16 is also equipped with an aeration means 34 that blows compressed air from an aeration blower 23. This blows air (oxygen) into the sludge wastewater treated in the first to third aeration tanks 13 to 15 and agitates the interior, allowing the aerobic bacteria (an example of aerobic bacteria) contained in the wastewater to consume and decompose organic matter. The carrier tank 16 can also be used as a fourth aeration tank following the third aeration tank 15 without introducing carriers.

[0022] The settling tank 17 receives the sludge wastewater treated in the first to third aeration tanks 13-15 and the carrier tank 16, i.e., the sludge wastewater that has been aerated and aerobic treated, and separates it into sludge (sediment) and supernatant (treated water). The sludge that settles in the settling tank 17 is sent to the regeneration tank 18, and the supernatant separated in the settling tank 17 is sent to the concentration adjustment tank 19 located downstream of the settling tank 17. A center well 35 and an air lift pump are located in the settling tank 17. The center well 35 carries the sludge wastewater sent from the carrier tank 16 down the inside of the tank to the bottom to prevent it from spreading within the settling tank 17. The sludge from the sludge wastewater carried to the bottom remains at the bottom due to its high specific gravity, enhancing the separation effect. The air lift pump has a very simple structure consisting of a sludge lift pipe and an air supply pipe. By connecting the air supply pipe to the end of the sludge lift pipe (near the bottom of the settling tank) and releasing air, the sludge water mixes with the air, lightening its specific gravity. The lighter mixed sludge water then rises through the sludge lift pipe due to external water pressure and buoyancy and is discharged. If the settling tank 17 containing sludge wastewater is left unstirred, the sludge will settle to the bottom and separate into a non-settling supernatant and a settling sludge. Therefore, the settling tank 17 has a conical section 36 at its bottom, whose diameter gradually decreases toward the bottom, and a cylindrical section 37 formed above it, to facilitate sludge accumulation at the bottom. The shape of the bottom of the settling tank may be a pyramidal section or other shape, and is not particularly limited.

[0023] The regeneration tank 18 receives the sludge accumulated in the settling tank 17 and further aerates it. This regeneration tank 18 has an aeration means 38, which blows compressed air (bubbles) into the tank using an aeration blower 23, further promoting the aerobic bacteria's action and the decomposition of organic sludge. The sludge (treated product) subjected to air aeration in the regeneration tank 18 contains the remaining enzymes (hereinafter also referred to as "residual enzymes") and wood powder introduced into the first aeration tank 13, the aerobic bacteria (live and dead) contained in the sludge wastewater, and enzymes produced by the aerobic bacteria. The regeneration tank 18 is equipped with a membrane separation means 39 for separating and recovering an advanced treatment liquid with reduced COD (chemical oxygen demand) from the sludge in the regeneration tank 18. The membrane separation means 39 can be, for example, a flat membrane made of resin, and its configuration can be a reverse osmosis membrane (RO membrane), a nanofiltration membrane (NF membrane), an ultrafiltration membrane (UF membrane), a microfiltration membrane (MF membrane), etc., but is not particularly limited as long as it can separate the highly treated liquid (into liquid and solids) from the sludge.

[0024] The circulation path 22 is a pipe that supplies sludge treated in the regeneration tank 18 to the first aeration tank 13. Specifically, sludge in the regeneration tank 18 is extracted by a pump 40 and sent to the first aeration tank 13 via a return sludge metering means 41 provided in the circulation path 22. This return sludge metering means 41 is a device that can control the amount of sludge passing through to a constant amount and return excess sludge to the regeneration tank 18. For example, a device with a configuration similar to the raw water transfer adjustment means 29 described above can be used, but there is no particular limitation as long as it has a configuration that can adjust the amount of sludge supplied. Here, the wood powder, residual enzymes, enzymes produced by aerobic bacteria and enzymes from dead aerobic bacteria themselves (hereinafter also referred to as enzymes derived from aerobic bacteria) are circulated and reused. Therefore, the enzymes supplied to the first aeration tank 13 and discharged together with the supernatant liquid are replenished with enzymes derived from aerobic bacteria and residual enzymes, and the wood powder supplied to the first aeration tank 13 is resistant to decay and remains without being consumed, so the amount of new wood powder (and further enzymes) added to the first aeration tank 13 can be reduced.

[0025] If the amount of the recycled enzyme supplied to the first aeration tank 13 is insufficient, for example, if the supernatant liquid separated in the settling tank 15 contains a large amount of enzyme or if the amount of enzyme derived from aerobic bacteria is small, new enzyme can be supplied to the first aeration tank 13 to make up for the shortage (if wood powder contains the enzyme, the shortage can be made up by adding wood powder). If the amount of recycled wood powder supplied to the first aeration tank 13 is insufficient, for example, if the wood powder is decomposed by aerobic bacteria, new wood powder can be supplied to the first aeration tank 13 by the wood powder adding means 33 to make up for the shortage.

[0026] The concentration adjustment tank 19 receives the supernatant liquid separated in the settling tank 17 and adjusts the COD (COD value) and / or BOD (BOD value) of the supernatant liquid to a concentration below that at which it can be discharged outside the system, i.e., into a sewer or a river. The treated liquid, whose concentration has been adjusted in the concentration adjustment tank 19, flows into the discharge tank 20 by head. The concentration adjustment tank 19 is equipped with an agitator 42, a COD meter 43, and a baffle 44. The agitator 42 is a device for homogenizing the concentration of the liquid in the concentration adjustment tank 19 by agitation. The COD meter 43 is a device for measuring the COD of the liquid in the concentration adjustment tank 19. The baffle 44 suppresses or even prevents the treated liquid from flowing into the discharge tank 20 due to the influence of agitation. Here, a COD meter 43 is used because a BOD meter is not present. Since a decrease in COD simultaneously decreases BOD, and an increase in COD simultaneously increases BOD, an approximate BOD value can be calculated using the COD meter 43. In use, the supernatant liquid received from the settling tank 17 is measured by the COD meter 43. If the measured COD is below the concentration at which the water can be discharged to the system, the supernatant liquid is allowed to overflow from the concentration adjustment tank 19 and flow into the discharge tank 20 by head drop. On the other hand, if the COD measured by the COD meter 43 exceeds the concentration at which the water can be discharged to the system in the future (assuming that it will exceed this concentration), the COD-reduced advanced treatment liquid is supplied to the concentration adjustment tank 19 via a pipe (not shown) connected to the membrane separation means 39, and the COD of the treated water in the concentration adjustment tank 19 is adjusted to a concentration at which the water can be discharged to the system or below.

[0027] Here, measurement by the COD meter 43 is preferably performed continuously, but may also be performed periodically (intermittently). The supply of the advanced treatment liquid to the concentration adjustment tank 19 is performed when the concentration exceeds the dischargeable concentration in the future. The future may refer to, for example, a COD (preset COD) that takes into account a safety margin relative to the dischargeable environmental standard, or a COD trend (predicted curve) estimated from the COD measured by the COD meter 43. The supply of the advanced treatment liquid to the concentration adjustment tank 19 is preferably performed automatically using a control means. For example, the COD measured by the COD meter 44 is transmitted to the control means, and based on the transmitted COD, the control means activates the membrane separation means 39 and supplies a preset amount of the advanced treatment liquid to the concentration adjustment tank 19. In this case, the control means is preset with a COD that takes into account a safety margin relative to the dischargeable environmental standard, and the control means calculates and processes the COD trend.

[0028] The discharge tank 20 stores the treated liquid received from the concentration adjustment tank 19 and periodically discharges it outside the system (to the sewer or a river). This treated liquid has, for example, an activated sludge suspended solids concentration of 250 mg / L or less and a BOD of 160 mg / L or less (more specifically, 10 to 50 mg / L), and is ready for discharge. Since the treated liquid contains enzymes, it can be pumped up with a pump 45 and effectively reused (reused). The BOD and COD mentioned above indicate indicators of organic matter contained in wastewater. Since BOD and COD are interrelated, COD, which can be measured in a shorter time, is used. Therefore, it is advisable to understand the correlation between BOD and COD in advance.

[0029] The sludge storage tank 21 is a tank that stores the sludge accumulated in the regeneration tank 18 and the concentration adjustment tank 19. Specifically, excess sludge from the sludge treated in the regeneration tank 18 is removed by a pump 46, and sludge accumulated in the concentration adjustment tank 19 is removed by a pump 47 and supplied to the sludge storage tank 21. The sludge stored in the concentration adjustment tank 19 is periodically removed by a pump 48 and subjected to a dehydration treatment or extraction treatment. Note that reference numerals 49 to 51 in Fig. 1 designate check valves.

[0030] As described above, by combining the enzyme activation treatment method with the membrane separation means 39, sludge wastewater containing organic sludge can be treated more stably than before, to the extent that it can be discharged into a river or the sea. Furthermore, by adopting the enzyme activation treatment method, the amount of sludge generated during treatment can be reduced, which, for example, makes it possible to downsize the membrane separation means 39 and reduce the costs required for replacement and cleaning. Note that sludge wastewater is supplied to the first aeration tank 13 at a predetermined flow rate via the raw water transfer adjustment means 29, and sludge is supplied from the regeneration tank 18 to the first aeration tank 13 at a predetermined flow rate via the return sludge metering means 41, so that the treatment volume of each tank can be limited, preventing overload and ensuring reliable treatment of sludge wastewater.

[0031] Next, a method for treating sludge wastewater according to one embodiment of the present invention will be described with reference to FIG. 1. (Preparation Process) First, sludge wastewater containing organic sludge is received in the raw water tank 11 and agitated using the aeration means 24. This sludge wastewater has an activated sludge suspended solids (MLSS) concentration of, for example, 3000 to 6000 mg / L. Note that if the MLSS concentration is less than 3000 mg / L, the amount of organic matter is small and the purification process does not proceed smoothly. If the MLSS concentration is more than 6000 mg / L, sedimentation and separation in the settling tank 17 may not be efficient. Next, the sludge wastewater that has been agitated in the raw water tank 11 is pumped up using the pump 26. Any debris mixed in the sludge wastewater is removed using the screening means 25, and the sludge wastewater is then stored in the flow rate adjustment tank 12.

[0032] (First Step) Sludge wastewater stored in the flow rate adjustment tank 12 is pumped up by a pump 28 and supplied to the first aeration tank 13 via the raw water transfer adjustment means 29. The first aeration tank 13 (one or more of the first to third aeration tanks 13-15) is supplied with decay-resistant wood powder capable of supporting the aerobic bacteria contained in the sludge wastewater, and enzymes. The wood powder may contain the enzymes described above. Air (oxygen) is supplied to the first to third aeration tanks 13-15 from aeration means 30-32, respectively, and the interior is agitated (aeration treatment), thereby performing aerobic bacterial treatment. Sludge wastewater overflowing from the third aeration tank 15 flows downhill into the carrier tank 16. Air (oxygen) is supplied to this carrier tank 16 from aeration means 34, and the interior is agitated, thereby performing aerobic bacterial treatment using the carriers.

[0033] (Step 2) The sludge wastewater is aerated sequentially in the first to third aeration tanks 13-15 and further treated in the carrier tank 16. The sludge wastewater is then supplied to the settling tank 17. The sludge is allowed to settle to the bottom without stirring for a certain period of time, separating the supernatant liquid from the settling sludge. This supernatant water is essentially organic-free, with an activated sludge suspended solids concentration of 250 mg / L or less and a BOD of 160 mg / L or less (more specifically, 10-50 mg / L). Therefore, it can be stored in a discharge tank and periodically discharged into a river or the sea. However, fluctuations in the BOD of the sludge wastewater being treated and the effects of climate change may have some impact on the production of a stable supernatant liquid. Therefore, the supernatant water is sent to the concentration adjustment tank 19. The sludge that settles in the settling tank 17 is removed by a pump 35 and sent to the regeneration tank 18.

[0034] (Third Step) The sludge removed from the settling tank 17 is placed in the regeneration tank 18. In this regeneration tank 18, air is sent in from the aeration means 38 (aeration treatment), which allows the aerobic bacteria to act further and promote the decomposition of the sludge. As described above, the sludge generated by the treatment in the regeneration tank 18 contains the remaining enzymes and wood powder, the aerobic bacteria (live and dead) that were contained in the sludge wastewater, the enzymes produced by the aerobic bacteria, etc.

[0035] This sludge is removed by pump 40 and sent to the first aeration tank 13 via the circulation path 22. Here, the wood powder, the enzymes derived from the aerobic bacteria, and the remaining enzymes are recycled (i.e., steps 1 to 3 are repeated). If the amount of recycled enzymes supplied to the first aeration tank 13 is insufficient, new enzymes can be supplied to the first aeration tank 13 (if the wood powder contains enzymes, new wood powder can be supplied by the wood powder addition means 33). Also, if the amount of recycled wood powder supplied to the first aeration tank 13 is insufficient, new wood powder can be supplied to the first aeration tank 13 by the wood powder addition means 33. Here, an insufficiency in the supply of enzymes and / or wood powder can be determined, for example, from the activated sludge suspended solids concentration of the treatment liquid in the concentration adjustment tank 19 and the results of measurements of BOD and COD (COD meter 42).

[0036] (Concentration Adjustment Step) The COD of the supernatant liquid sent to the concentration adjustment tank 19 is measured by a COD meter 42. If the measured COD of the supernatant liquid in the concentration adjustment tank 19 is below the concentration at which it can be discharged to the outside of the system, i.e., if the discharge conditions of the activated sludge suspended solids concentration being 250 mg / L or less and the BOD being 160 mg / L or less are satisfied, the supernatant liquid is stored as is in the discharge tank 20 and periodically discharged into a river or the sea. Note that the supernatant liquid contains enzymes and has cleaning and organic matter decomposition effects, so it can be pumped up with a pump 45 and reused as is. On the other hand, if the measured COD of the supernatant liquid in the concentration adjustment tank 19 exceeds the concentration at which it can be discharged to the outside of the system in the future, i.e., if the discharge conditions cannot be satisfied, the concentration adjustment tank 19 receiving the supernatant liquid is supplied with a highly treated liquid with reduced COD, which has been separated and recovered from the sludge in the regeneration tank 18 by a membrane separation means 39, to adjust the concentration adjustment tank 19 so that the discharge conditions are satisfied. The COD of the highly treated liquid is reduced to a concentration below that at which it can be discharged outside the system, and although there are no particular limitations, the BOD is preferably 100 mg / L or less, more preferably 50 mg / L or less, and even more preferably 20 mg / L or less.

[0037] As described above, by combining the enzyme activation treatment method with the membrane separation means 39, it is possible to treat sludge wastewater containing organic sludge more stably than before to the extent that it can be discharged into rivers or the sea. Furthermore, by adopting the enzyme activation treatment method, the amount of sludge generated during treatment can be reduced, which makes it possible to, for example, downsize the membrane separation means 39 and reduce the costs required for replacement and cleaning.

[0038] The present invention has been described above with reference to the examples. However, the present invention is not limited to the configurations described in the above examples and includes other embodiments and modifications conceivable within the scope of the claims. For example, the scope of the present invention also includes a sludge wastewater treatment system and treatment method that combines some or all of the above examples and modifications. In the above examples, sludge wastewater treatment is performed using a combination of continuous and batch treatments, but it can also be performed entirely using continuous or batch treatments. Furthermore, in the above examples, the case where treated water treated in the concentration adjustment tank is discharged via a discharge tank is described. However, the treated water from the concentration adjustment tank can also be discharged directly without using a discharge tank.

[0039] The sludge and wastewater treatment equipment and treatment method of the present invention can efficiently and stably treat sludge and wastewater containing organic sludge discharged from ordinary homes, office buildings, various factories, etc., while reducing or even preventing environmental load, and can make the treated water to a level that can be discharged into rivers or the sea, thereby finding industrial applicability in wastewater treatment projects, water environment conservation projects, etc.

[0040] 10: Sludge wastewater treatment equipment, 11: Raw water tank, 12: Flow rate adjustment tank, 13: First aeration tank, 14: Second aeration tank, 15: Third aeration tank, 16: Carrier tank, 17: Settling tank, 18: Regeneration tank, 19: Concentration adjustment tank, 20: Discharge tank, 21: Sludge storage tank, 22: Circulation path, 23: Aeration blower, 24: Aeration means, 25: Screen means, 26: Pump, 27: Aeration means Stage, 28: Pump, 29: Raw water transfer adjusting means, 30-32: Aeration means, 33: Wood powder adding means, 34: Aeration means, 35: Pump, 36: Conical portion, 37: Cylindrical portion, 38: Aeration means, 39: Membrane separation means, 40: Pump, 41: Return sludge measuring means, 42: COD measuring instrument, 43: Agitator, 44: Baffle plate, 45-48: Pump, 49-51: Check valve

Claims

1. A sludge wastewater treatment facility having an aeration tank for receiving sludge wastewater containing organic sludge and aerating the sludge wastewater, a settling tank for receiving sludge wastewater aerated in the aeration tank and separating the sludge wastewater into sediment and treated water, a regeneration tank for receiving sediment accumulated in the settling tank and further aerating the sediment, and a circulation path for supplying the treated material treated in the regeneration tank to the aeration tank, wherein the aeration tank uses wood powder having a particle size of 1 mm or less as a carrier for enzymes that promote the decomposition of the organic sludge and aerobic bacteria that decompose the organic sludge, a concentration adjustment tank is installed downstream of the settling tank for receiving the treated water separated in the settling tank and adjusting the chemical oxygen demand of the treated water to a concentration below that at which it can be discharged outside the system, and the regeneration tank is equipped with a membrane separation means for separating and recovering advanced treatment liquid with reduced chemical oxygen demand from the treated material in the regeneration tank, said membrane separation means separates and recovers the advanced treatment liquid, and supplies it to said concentration adjustment tank, on the condition that the chemical oxygen demand of the treated water in said concentration adjustment tank will exceed the concentration at which it can be discharged outside the system in the future.

2. A sludge wastewater treatment facility according to claim 1, characterized in that said wood powder contains said enzymes.

3. A sludge wastewater treatment facility as claimed in claim 1 or 2, characterized in that new wood powder is supplied to the aeration tank to make up for any shortfall in the amount of wood powder being recycled and supplied to the aeration tank.

4. A method for treating sludge wastewater comprising the steps of: a first step of feeding sludge wastewater containing organic sludge into an aeration tank; and supplying and aerating said aeration tank wood powder with a particle size of 1 mm or less capable of carrying enzymes that promote the decomposition of the organic sludge and aerobic bacteria that decompose the organic sludge; a second step of feeding the sludge wastewater treated in the first step into a settling tank to separate it into sediment and treated water; and a third step of feeding the sediment generated in the second step into a regeneration tank for aeration treatment, wherein when the treated product treated in the third step is supplied to the aeration tank and the wood powder is recycled, a concentration adjustment tank receiving the treated water is supplied with an advanced treatment liquid with reduced chemical oxygen demand that has been separated and recovered from the treated product in the regeneration tank by a membrane separation means provided in the regeneration tank, on the condition that the chemical oxygen demand of the treated water generated in the second step exceeds a concentration that can be discharged outside the system in the future, thereby adjusting the chemical oxygen demand of the treated water in the concentration adjustment tank to a concentration that can be discharged outside the system or lower.

5. A method for treating sludge wastewater according to claim 4, wherein said wood powder contains said enzymes.

6. A method for treating sludge wastewater as claimed in claim 4 or 5, characterized in that when the amount of the recycled wood powder supplied to the aeration tank becomes insufficient, new wood powder is supplied to the aeration tank.