Circulation type sewage sludge recycling system

Abstract

To provide a sewage sludge recycling system which solves the problems of a conventional closed composting apparatus.SOLUTION: A primary fermentation treatment means including a dehydration means for dehydrating the sewage sludge to form a raw material and a horizontal shaft rotation fermentation treatment vessel, and fermenting the raw material to produce a primary fermented product having a first set water content value or less, a secondary fermentation treatment means provided on a discharge end side of the fermentation treatment vessel and further fermenting the primary fermented product to produce a secondary fermented product having a second set water content value or less having a lower water content, and a carbonization means for carbonizing the secondary fermented product to produce a carbonized product; The system for converting sewage sludge into resources is equipped with a mixing means for mixing them to prepare a mixture and a water content measuring means for measuring the water content of the primary fermented product and a means for distributing and supplying at least a part of the mixture to a raw material supply means and / or a processing means for processing the mixture into a third useful material is connected to the mixing means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circulatory sewage sludge recycling system. [Background technology]

[0002] The Ministry of Land, Infrastructure, Transport and Tourism issued the following notice in National Water and Sewerage Planning No. 99 on March 17, 2023, to the heads of the sewerage departments of each prefecture and each designated city: "Basic Concepts for the Treatment of Generated Sludge, etc. Article 21-2, paragraph 2 of the Sewerage Act stipulates that "When treating generated sludge, etc., efforts shall be made to reduce its volume by dehydration, incineration, etc., and efforts shall be made to recycle the generated sludge, etc. as fuel or fertilizer." With Japan's goal of achieving carbon neutrality by 2050 and the need to switch to domestic alternatives for production materials in order to strengthen food security, the need for the use of sewage sludge as energy and fertilizer is increasing. In particular, with regard to its use as fertilizer, the "Outline of Food Security Enhancement Policy" (decided by the Headquarters for Stable Food Supply and Strengthening of Agriculture, Forestry and Fisheries Infrastructure on December 27, 2022) indicated that the amount of sewage sludge and compost used as fertilizer will be doubled by 2030, and the proportion of domestic resources used in fertilizer (phosphorus base) will be increased to 40%. In light of this background, in order to further expand our contribution to the realization of a recycling-oriented society through sewerage projects, we have established the following basic principles regarding the future treatment of generated sludge, etc. We ask that you fully understand this policy and strive to implement sewerage projects. We ask that each prefecture make this known to the cities, towns and villages within its jurisdiction (excluding designated cities). Please note that this notice is technical advice based on the provisions of Article 245-4, Paragraph 1 of the Local Autonomy Act (Act No. 67 of 1947).

[0003] A known example of an apparatus for recycling organic waste such as sewage sludge is a sewage sludge recycling system, or closed-type sewage sludge recycling system (hereinafter referred to as a closed-type composting apparatus), which comprises a horizontal cylindrical fermentation vessel in which the raw organic waste is fermented using aerobic hyperthermophilic bacteria (hereinafter sometimes referred to as hyperthermophilic bacteria), a raw material hopper located at one end of the fermentation vessel for temporarily storing the raw organic waste, raw material supply means for supplying the raw material temporarily stored in the raw material hopper into the fermentation vessel, and a discharge means located at the other end of the fermentation vessel for discharging the fermented raw material from the fermentation vessel.The fermentation vessel is rotated around its central axis, gradually moving the raw material from one end to the other end of the fermentation vessel over a predetermined number of days while fermenting, thereby recycling the organic waste into a resource, i.e., composting and fertilizer.

[0004] Furthermore, JP 2005-320182 A aims to provide a technology that produces compost from organic waste, circulates the compost to produce new liquid fertilizer and compost, and is energy efficient and contributes to environmental conservation. To achieve this aim, claim 1 of the document states, "The document relates to an organic waste composting treatment system for producing compost and liquid fertilizer from organic waste consisting of solid waste and liquid waste." That is, the present invention provides an organic waste composting treatment system comprising: a crushing and mixing device equipped with a crushing mechanism for crushing the solid waste and a microorganism injection mechanism for injecting and mixing microorganisms into the solid waste at the crushing or crushing stage; a decomposition and fermentation device that sends the solid waste crushed and mixed by the crushing and mixing device to a decomposition and fermentation mechanism where the solid waste is decomposed and fermented by the activity of microorganisms, thereby producing fully matured compost from the solid waste; and a liquid fertilizer production device that produces liquid fertilizer using a portion of the fully matured compost produced by the decomposition and fermentation device and the liquid waste as raw materials. Claim 2 further limits the organic waste composting treatment system described in claim 1, proposing an organic waste composting treatment system characterized in that the crushing and mixing device is equipped with a circulation mechanism that injects the fully matured compost into the crushed solid waste and mixes it.

[0005] According to the organic waste composting treatment system described in claim 2, the circulation mechanism of the shredding / mixing device introduces a portion of the fully matured compost into the device. The shredding / mixing device mixes the solid waste and the fully matured compost. Therefore, the fully matured compost is returned by the circulation mechanism, which promotes decomposition and fermentation without the need for a microbial introduction mechanism such as a culture medium. This reduces the utilization rate of microorganisms used in the microbial introduction mechanism, contributing to cost reduction.

[0006] According to the organic waste composting treatment system described in claim 2, the circulation mechanism of the shredding / mixing device takes in a portion of the fully matured compost into the device. The shredding / mixing device mixes the solid waste and the fully matured compost. Therefore, the fully matured compost is returned by the circulation mechanism, which promotes decomposition and fermentation without the need for a microbial introduction mechanism such as culture media. This allows for a reduction in the rate of microorganism usage in the microbial introduction mechanism, contributing to cost reduction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-320182 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, according to the organic waste composting treatment system described in claim 2, fully matured compost is returned by the circulation mechanism, which makes it possible to promote decomposition and fermentation without the need for a microbial introduction mechanism such as culture media. This reduces the rate at which microorganisms are used in the microbial introduction mechanism, and is expected to contribute to cost reductions. However, as stated in the specification, it takes 30 to 90 days for the compost to become fully matured enough to be used.

[0009] In contrast, the sealed composting equipment mentioned earlier can produce fully matured compost in around 20 days, but depending on the condition of the raw materials, the compost may be discharged from the equipment while still immature.

[0010] Therefore, the present invention aims to provide a sewage sludge recycling system that utilizes the structure of the above-mentioned closed composting apparatus, takes advantage of its advantages, incorporates the advantages of the organic waste composting treatment system disclosed in JP 2005-320182 A, and further improves it, thereby eliminating the above-mentioned problems of the closed composting apparatus. [Means for solving the problem]

[0011] The above problems are solved by a sewage sludge recycling system having the following configurations (1) to (17). (1) A recycling-type sewage sludge recycling system that converts sewage sludge, which is organic waste, into useful materials. This recycling-type sewage sludge recycling system: a dehydration means for dehydrating the sewage sludge to a predetermined moisture content value to form a raw material; a primary fermentation treatment means having a horizontal cylindrical fermentation treatment vessel that rotates around a central axis, which rotates the fermentation treatment vessel around the central axis while gradually moving a raw material from an inlet end toward a discharge end within the fermentation treatment vessel over a predetermined number of days, and fermenting the raw material with aerobic microorganisms to produce a primary fermented product having a moisture content of not more than a first set value; a raw material supply means provided at the inlet end of the fermentation treatment vessel for receiving the raw material from the dehydration means and supplying the raw material into the fermentation treatment vessel; a primary fermentation product discharge means provided on the discharge end side of the fermentation treatment vessel for discharging the primary fermentation product outside the fermentation treatment vessel; a secondary fermentation treatment means for receiving the primary fermented product from the primary fermentation treatment means and additionally fermenting the primary fermented product to produce a secondary fermented product having a moisture content lower than that of the primary fermented product and not exceeding a second set moisture content value; a carbonization means for receiving the secondary fermented product from the secondary fermentation treatment means and carbonizing the same to produce a carbonized product; a mixing means for receiving the secondary fermented product from the secondary fermentation treatment means and the carbonized product from the carbonization means and mixing them to prepare a mixture; and a moisture content measuring means for measuring the moisture content of the primary fermentation product discharged from the primary fermentation product discharge means, A first allocating and supplying means is connected to the primary fermentation treatment means, and this first allocating and supplying means allocates the first fermented product to the secondary fermentation treatment means and to a first useful resource processing means for processing the remaining amount into a first useful product of a first form when the moisture content value of the primary fermented product measured by the moisture content measuring means is equal to or less than the first set moisture content value under normal circumstances, and supplies the entire amount of the primary fermented product to the secondary fermentation treatment means when the moisture content value exceeds the first set moisture content value under emergency circumstances. a second distribution / supply means is connected to the secondary fermentation treatment means, and the second distribution / supply means distributes and supplies at least a portion of the secondary fermented product to the carbonization means and the mixing means, respectively; A third distribution supply means is connected to the mixing means, and this third distribution supply means is configured to distribute and supply at least a part of the mixture to the raw material supply means and / or a third useful resource processing means for processing the mixture into a third useful product of a third form. A recycling-type sewage sludge recycling system characterized by the following characteristics. (2) The sewage sludge recycling system (1) is characterized in that the secondary fermentation treatment means is either a pile-up type using a compost shed, an open type using a rotary scoop agitator, or a closed agitation type using a composter. (3) The sewage sludge recycling system of (2) is provided with: a production section in which the aerobic microorganisms are gram-positive aerobic thermophiles; the secondary fermentation treatment means is a sedimentation-type fermentation treatment means that sediments the primary fermented product supplied from the first distribution / supply means, and produces a secondary fermented product from the sedimented primary fermented product using the gram-positive aerobic thermophiles to produce a secondary fermented product with a second set moisture content that is lower than the first set moisture content of the primary fermented product; a storage section in which the secondary fermented product produced in the production section is stored; and a secondary fermented product discharge means for discharging a predetermined amount of the secondary fermented product from the storage section. (4) The sewage sludge recycling system according to (1), wherein the third distributing and supplying means distributes and supplies the mixture to the raw material supplying means in the emergency. (5) The sewage sludge recycling system of (1) is configured such that the third distribution supply means supplies a predetermined amount of the mixture to a biological treatment section of a sewage treatment facility in a state in which the aerobic microorganisms in the secondary fermentation product of the mixture have been activated via a microbial activation means. (6) The sewage sludge recycling system according to (3), wherein the secondary fermentation treatment means is provided with a supply conveyor that supplies the primary fermented product supplied from the first distribution supply means to the production section. (7) The sewage sludge recycling system according to (3), wherein the secondary fermentation treatment means is provided with a transfer means for transferring the secondary fermented product produced in the production section from the production section to the storage section. (8) The production section of the secondary fermentation treatment means is equipped with a second moisture content measuring means for measuring the moisture content of the produced secondary fermented product, a transport and return means that is installed over almost the entire length of the production section and is switchable between a transport state in which the primary fermented product is transported from the upstream side to the downstream side and a return state in which the secondary fermented product is returned from the downstream side to the upstream side, and an operation control means that controls the switching between the transport state and the return state of the transport and return means in accordance with the moisture content of the secondary fermented product measured by the second moisture content measuring means, in the sewage sludge recycling system of (3). (9) The sewage sludge recycling system (8) wherein the operation control means controls the conveying and returning means to switch to a returning state when the moisture content value of the secondary fermentation product measured by the second moisture content measuring means exceeds the second set moisture content value. (10) The sewage sludge recycling system (1) described above, wherein the first set moisture content value is 35% or less, and the second set moisture content value is set 2 to 15% lower than the first set moisture content value. (11) The sewage sludge recycling system according to (1), wherein the mixture processed by the third useful resource processing means is a soil improvement material and compost / fertilizer. (12) The sewage sludge recycling system according to (1) above, wherein the fermentation treatment vessel is provided with a stirring means for stirring the raw material therein. (13) The sewage sludge recycling system according to (12), wherein the agitation means is a rotation actuation means for rotating the fermentation treatment vessel. (14) the raw material supply means has a raw material hopper for temporarily storing the raw material from the dehydration means, and the raw material hopper is surrounded by a jacket with a gap between the outer wall of the raw material hopper and the jacket to form a heating gas space through which a heating gas for heating the raw material in the raw material hopper passes; a heated gas passage extending from the discharge end of the fermentation treatment vessel to the heated gas space, for supplying exhaust gas generated as a result of fermentation in the fermentation treatment vessel from the fermentation treatment vessel to the heated gas space as heated gas; The sewage sludge recycling system according to (1) above, (15) The sewage sludge recycling system according to (1), wherein the aerobic microorganisms include those belonging to the gram-positive Bacillus class of the phylum Firmicutes, and / or those belonging to the gram-positive Actinobacteria class of the phylum Actinobacteria, and / or those belonging to the gram-positive Chloroflexus phylum. (16) The sewage sludge recycling system according to any one of (1) to (15), wherein the carbonization means is a carbonization means for producing activated carbon using the secondary fermentation product as a raw material. (17) The sewage sludge recycling system (1) is configured so that the second distribution and supply means can distribute and supply at least a portion of the secondary fermentation product to the raw material supply means and / or a second useful resource processing means that processes the secondary fermentation product into a second useful product of a second form. [Effects of the Invention]

[0012] The sewage sludge recycling system of the present invention further ferments the primary fermentation product (usually with a moisture content of 35% or less) produced by the primary fermentation treatment means to produce a secondary fermentation product with a moisture content lower than that, and then carbonizes this secondary fermentation product to produce a carbonized product, particularly activated carbon. This carbonized product can be used as a moisture content adjuster to normalize the fermentation of dewatered sludge, or can be added to a biological treatment tank in a sewage treatment facility to significantly reduce BOD and COD. In addition, since a mixture of the carbonized product and secondary fermentation product is produced in the present invention, the microorganisms in the secondary fermentation product also contribute to sewage treatment. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram conceptually illustrating a circulatory sewage sludge recycling system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a detailed diagram showing details of the primary fermentation treatment device and the like of the sewage sludge recycling system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circulatory sewage sludge recycling system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0015] The sewage sludge recycling system 10 comprises a primary fermentation treatment device 11 having a horizontal cylindrical shape and a fermentation treatment vessel 12 in which the raw material, sewage sludge, i.e., organic waste, is fermented by aerobic microorganisms, particularly aerobic thermophiles, a raw material supply means 20 provided at the inlet end 12a of the fermentation treatment vessel, and a discharge means 30, which is a discharge gate provided at the discharge end 12b of the fermentation treatment vessel 12 and which discharges the primary fermented product produced by fermenting the raw material m, out of the fermentation treatment vessel. The raw material supply means 20 and discharge means 30 are controlled by an operation synchronization means 140 so that their operations are synchronized.

[0016] The raw material supply means 20 has a raw material hopper 22 that temporarily stores raw material m from dehydration means 15, which dehydrates sewage sludge, which is organic waste, to a predetermined raw material moisture content value to form raw material m, and this raw material hopper 22 is provided with a conveyor 24 for supplying the raw material temporarily stored therein into the fermentation treatment vessel 12.

[0017] As shown in Figure 2, the raw material hopper 22 is provided with a rotary agitator 26, which includes a rotating shaft 26a extending vertically into the raw material hopper and a horizontally extending agitator 26b, such as an agitator blade, attached to the rotating shaft 26a. The agitator rotates at a peripheral speed (e.g., about 0.1 to 0.5 m / s) that does not cause the raw material to fly up or the odor to diffuse, thereby agitating the raw material. This agitation of the raw material ensures a uniform distribution of the moisture content in the raw material.

[0018] As shown in FIG. 2, the fermentation vessel 12 has a pair of fixed end plates 14 and 16 and a cylindrical fermentation drum 18 rotatably mounted between them around a central axis. The inner wall of the fermentation drum 18 may be provided with propulsion blades (not shown). The fermentation drum 18 is rotated by a rotary drive unit (not shown), and the raw material introduced into the inlet end 12a is gradually moved toward the discharge end 12b by the propulsion blades over a predetermined number of days (e.g., about 21 days) while undergoing fermentation treatment, thereby converting the sewage sludge into a resource, i.e., composting and fertilizer. The movement of the raw material within the fermentation vessel 12 may also be achieved by the pushing of the raw material by the conveyor 24.

[0019] The fermentation is carried out by aerobic microorganisms, particularly aerobic thermophiles. According to the Biochemistry Dictionary (4th Edition) published by Tokyo Kagaku Dojin Co., Ltd., thermophiles generally refer to bacteria that can grow at temperatures above 55°C, with thermophiles that can grow at temperatures above 75°C being called extreme thermophiles and bacteria that can grow at temperatures above 90°C being called hyperthermophiles. In the present invention, it is desirable to use bacteria (microorganisms) that are extreme thermophiles or higher. As such aerobic extreme thermophiles, for example, Thermus thermophilus can be used. By fermenting organic waste using such aerobic extreme thermophiles, plant seeds and pathogenic bacteria in the raw materials that are harmful to plant growth can be decomposed and killed, for example, when the resource is converted into compost or fertilizer.

[0020] The sewage sludge recycling system 10 includes a secondary fermentation treatment facility 80 that receives the primary fermented product from the primary fermentation treatment device 11, further ferments it (with drying) to produce a secondary fermented product with a lower moisture content than the primary fermented product. The primary purpose of this secondary fermented product is to function as part of a material for adjusting the moisture content of the raw material, but its secondary purpose is to use it as compost or fertilizer in a different form (mode) from the above. The secondary fermentation treatment facility 80 is located on the primary fermented product receiving side, and includes a production unit 82 that processes the received primary fermented product to produce a secondary fermented product, and a storage unit 84 that stores the secondary fermented product produced in the production unit 82. Details of the structure will be described later.

[0021] A discharge passage 32 for the primary fermented product is connected to the discharge gate 30, and a first distributing / supplying device 34 is provided at the downstream end of the discharge passage 32. The distributing / supplying device 34 is equipped with a three-way valve 36 and an operation control means 38 for controlling the valve. One discharge port of the three-way valve 36 is connected to a first supply passage 40 for supplying a first set amount of the primary fermented product to the secondary fermentation treatment equipment 80, which processes the primary fermented product into the secondary fermented product, and the other discharge port is connected to a second supply passage 42 for supplying a second set amount of the primary fermented product to a first useful resource processing means (not shown), which processes the primary fermented product into a first useful product. The secondary fermentation treatment equipment 80 is equipped with a supply conveyor, and the primary fermented product from the first supply passage 42 is supplied to a production section 82 of the secondary fermentation treatment equipment 80 by this supply conveyor.

[0022] An operation panel 70 is connected to the operation control means 38, which is operated by an operator to issue commands to the operation control means 38. The operator operates this operation panel 70 to control the operation control means 38, thereby adjusting the distribution rate (distribution amount) of the primary fermentation product distributed by the three-way valve 36 when the primary fermentation treatment device 11 is functioning normally. This distribution rate (distribution amount) is set, for example, to 1 / 5 on the first supply passage 40 side and 4 / 5 on the second supply passage 42 side.

[0023] A moisture content sensor 44 is arranged in the primary fermentation product discharge portion of the primary fermentation treatment device 11, for example, in the discharge end 12b where the discharge gate 30 of the fermentation treatment vessel 12 is provided, as shown in Figure 1, and this moisture content sensor 44 measures the moisture content of the primary fermentation product discharged from the fermentation treatment vessel 12 and outputs a signal S1 indicating the value to the operation control means 38.

[0024] The operation control means 38 compares the received signal S1, indicating the moisture content of the primary fermentation product, with a predetermined moisture content (e.g., 35%, indicating a predetermined degree of fertilizer maturity) to determine whether the moisture content is below that value (normal) or above that value (emergency). Under normal conditions, the operation control means 38 controls the three-way valve 36 to distribute the primary fermentation product in the above ratio. On the other hand, under emergency conditions, the operation control means 38 closes the second supply passage 42 side of the three-way valve 36 so that the entire amount of the primary fermentation product is supplied to the first supply passage 40 side. As a result, if the primary fermentation product is not in a state desirable for use as a first useful resource, it is not supplied to the first useful resource processing means. Therefore, the sewage sludge recycling system of this embodiment prevents defective useful resources from being distributed to the outside world.

[0025] The production section 82 of the secondary fermentation treatment equipment 80 serves as a secondary fermentation treatment means, which may be any of the following: a pile-up type using a compost shed, which has traditionally been used for compost production; an open type using a rotary scoop mixer; or a closed type mixer using a composter.

[0026] The secondary fermentation treatment equipment is preferably the heaping-type fermentation treatment means, and uses aerobic microorganisms, particularly gram-positive aerobic thermophiles, to perform high-temperature aerobic fermentation on the primary fermented product heaped in the production section 82 while maintaining a temperature of 60°C to 110°C and turning over the product, thereby producing a secondary fermented product with a second set moisture content that is lower than the first set moisture content of the primary fermented product. This high-temperature aerobic fermentation decomposes and kills gram-negative anaerobic and facultative anaerobic microorganisms, but the aerobic microorganisms used in the fermentation continue to survive as spores. Preferably, the aerobic microorganisms include those belonging to the Gram-positive class Bacilli of the phylum Firmicutes, and / or those belonging to the Gram-positive class Actinobacteria of the phylum Actinobacteria, and / or those belonging to the Gram-positive class Chloroflexi.

[0027] The manufacturing section 82 can also be configured as follows. That is, a blower fan is provided on the primary fermentation product receiving side of the production section 82 to blow oxygen (air) to the primary fermentation product accumulated in the production section 82, and a transport and return means consisting of a conveyor or the like is provided along almost the entire length of the interior of the production section 82 (from the primary fermentation product receiving side to the secondary fermentation product discharge side), so that the primary fermentation product supplied to the secondary fermentation treatment equipment 80 is fermented while transported by the transport and return means to become a secondary fermentation product with a predetermined second set moisture content value (a moisture content equal to or lower than a predetermined moisture content lower than the moisture content of the primary fermentation product, which is set to 2 to 15%, particularly 5%, lower than the first set moisture content value; therefore, specifically, when the first set moisture content value is 35%, this second set moisture content value is preferably 30%). The transport and return means is preferably provided with an operation control means for controlling the switching between transport and return, setting of the transport speed, and the like.

[0028] The secondary fermentation treatment equipment 80 is provided with a transfer means (not shown) on the discharge side of its production section 82 for transferring the produced secondary fermented product from the production section 82 to a storage section 84, and the operation of this transfer means is controlled by an operation control means.

[0029] A moisture content sensor is provided in a portion (downstream end) adjacent to the storage section 84 of the production section 82 of the secondary fermentation treatment equipment 80. This moisture content sensor is used to monitor whether the primary fermented product that has been transported to the downstream end of the production section 82 while being fermented has reached the specified moisture content for the desired secondary fermented product, and measures the moisture content of the primary fermented product (secondary fermented product) at the downstream end of the production section 82 and sends a signal S2 indicating the moisture content value to the operation control means.

[0030] The operation control means, upon receiving signal S2, determines whether the moisture content indicated by this signal is equal to or less than the predetermined moisture content (30%) for the secondary fermented product, and if the determination is YES, maintains the transport and return means in the transport state. On the other hand, if the determination is NO, switches the operation to the return state, returns the primary fermented product to the upstream side, and allows further fermentation to occur. The above process is repeated until the moisture content of the primary fermented product falls below the predetermined moisture content for the secondary fermented product.

[0031] On the other hand, the operation control means that has received the signal S2 determines whether the moisture content value indicated by this signal S2 is equal to or less than the predetermined moisture content value (30%) for the secondary fermented product, and if the determination is YES, it operates the transfer means to transfer the produced secondary fermented product to the storage section 84. On the other hand, if the determination is NO, it does not operate the transfer means, and therefore the incomplete product as the secondary fermented product is not transferred to the storage section 84.

[0032] A second distributing / supplying device 90 is connected to the discharge end of the storage section 84, and this second distributing / supplying device 90 may have substantially the same configuration as the first distributing / supplying device 34 except that it uses a valve mechanism that functions as a five-way valve, so detailed explanation of the structure etc. will be omitted. This second distributing / supplying device 90 distributes and supplies at least a portion of the secondary fermentation product to the raw material supplying means 20, a carbonization facility 100 described later, a mixing means 110 described later, and a second useful resource processing means (not shown) that processes the secondary fermentation product into a second useful material of a second form, respectively.

[0033] In the emergency, the second distributing and supplying device 90 may supply the secondary fermented product having a moisture content as low as 30% or less to the raw material supplying means 20. In this case, the secondary fermented product is mainly used to function as a material moisture content adjusting material for adjusting the moisture content value of the raw material, but also serves to add aerobic thermophilic bacteria, which are supported on its solid matter and function for fermentation treatment, to the raw material. In order to transport the above-mentioned secondary fermentation product, the sewage sludge resource recycling system 10 is provided with a raw material preparation material transport path 91 for transporting the secondary fermentation product (raw material preparation materials) from the secondary fermentation treatment equipment 80 to the raw material supply means 20 via a second distribution supply device 90.

[0034] As described above, the second distributing / supplying device 90 is connected to a carbonization raw material transport path 92 for transporting the secondary fermentation product to the carbonization equipment 100. The carbonization equipment 100 carbonizes, preferably converts the transported secondary fermentation product into activated carbon to produce a carbonized product, preferably activated carbon. Since the carbonization equipment itself can have a conventional structure and configuration, a detailed description thereof will be omitted. The carbonized material produced in the carbonization equipment 100, preferably activated carbon, has a low moisture content of about 10% (and also has a high porosity), so it can be used as a moisture content adjuster for raw materials in itself, just like the secondary fermentation product itself, but here it will be described as a raw material for forming a mixture with the secondary fermentation product.

[0035] The mixing means 110 is connected to the second distribution supply device 90 by a first mixed raw material conveying path 93 for conveying the secondary fermented product, and to the carbonization equipment 100 by a second mixed raw material conveying path 94 for conveying the carbonized product. The mixing means 110 uses a rotating agitator blade or the like to thoroughly mix the secondary fermented product and carbonized material delivered thereto to form a mixture. At this time, it is preferable to change the ratio of the secondary fermented product to the carbonized product depending on the moisture content of the primary fermented product, and this ratio is achieved by adjusting the amount of secondary fermented product from the second distributing and supplying device 90 or by providing a supply amount control means in the carbonization equipment 100 to adjust the amount of carbonized product. During this mixing, the secondary fermentation product itself or the microorganisms (or their spores) in the secondary fermentation product are adsorbed into the pores of the carbonized material, and the carbonized material serves as a carrier for at least the microorganisms (or their spores). The second distributing and supplying device 90 is connected to a second useful material supplying path 95 for supplying a secondary fermented product to the second useful resource processing means (not shown).

[0036] The mixing means 110 is connected to a third distributing / supplying device 120 which is provided with a valve mechanism as a four-way valve similar to the second distributing / supplying device 90 . This third distribution and supply device 120 is configured to distribute and supply at least a portion of the mixture to the raw material supply means 20, the microbial activation device 130 described below, and a third useful resource processing means (not shown) that processes the mixture into a third type of third useful product. For the above reasons, the third distribution and supply device 120 is connected to the raw material supply means 20 by a first mixture conveying path 96, to the microbial activation device 130 by a second mixture conveying path 97, and to the third useful resource processing means by a third mixture conveying path 98. Here, both the secondary fermented product and the mixture are supplied to the raw material supply means 20, and the switching between them and the control of the mixed state can be controlled based on the state of the primary fermented product as measured by the moisture content sensor 44 for the moisture content of the primary fermented product.

[0037] The microbial activation device 130 receives the mixture from the mixing means 110, oxygen from an oxygen supply means (not shown), and water from a water supply means (not shown), and maintains the water temperature at 10°C to 40°C and the oxygen concentration at 1 to 10 mg / L to germinate and activate the spores in the mixture, thereby producing a mixture containing activated microorganisms. The microbial activation device 130 is connected to a biological treatment tank 210 of a sewage treatment facility 200 via an activated microorganism-containing mixture transport path 220, and receives the activated microorganism-containing mixture via this path 220. In the biological treatment tank 210, the activated microorganisms biologically treat the sewage, and the carbonized material (especially activated carbon) significantly reduces the BOD and COD of the sewage. The dehydrator 15 receives and dehydrates return sludge from, for example, a final settling tank 212 connected to the biological treatment tank 210 of the sewage treatment facility. For this reason, a return sludge transport path 230 is connected between the dehydrator 15 and the final settling tank 212.

[0038] Here, the second useful product refers to a drier powdery fertilizer (compost) or the like, since the moisture content of the secondary fermentation product, which is the raw material, is set lower than that of the primary fermentation product. Furthermore, since the third useful substance is a mixture of secondary fermentation products and carbonized products, it also functions as a soil improvement material due to the fertilizer (compost) properties of the secondary fermentation products and the carbon fixation function of the carbonized products.

[0039] Here, the operation of the second and third distributing / supplying devices 90 and 120 in the normal state (when the moisture content indicated by the signal S1 is equal to or less than a predetermined value) and in the emergency state (when the moisture content indicated by the signal S1 exceeds a predetermined value) will be described. First, the operation of the second distributing / supplying device 90 will be described as a representative example.

[0040] First, it is assumed that 200 kg of dewatered sludge (raw material) m with a moisture content of 85% is discharged per hour for 5 hours per day from the dehydrator 15. Therefore, 1000 kg of raw material is supplied to the raw material supply means 20 per day.

[0041] Normal time If 5 parts by mass of a mixture (materials for adjusting raw material (secondary fermented product:carbonized product = 1:1, therefore moisture content 20%) is supplied to the raw material supply means 20 for 100 parts by mass of the raw material (dewatered sludge), the mixture supplied from the distribution supply device 102 to the raw material supply means 20 will be 10 kg per hour, and since it is supplied for 5 hours per day in synchronization with the dehydrator 15, it will be 50 kg per day. Therefore, the discharge amount of the mixture from the mixing means 110 must be 10 kg or more per hour, and 50 kg or more per day because it is supplied for 5 hours per day in synchronization with the dehydrator 15. In other words, the total amount of the mixture discharged from the mixing means 110 is the sum of the amount required as a raw material preparation material and the surplus amount. The surplus is supplied via a supply passage 98 to a third useful resource processing means (not shown) that processes the mixture into a third useful product, which is the second useful resource.

[0042] The operation panel is used to set the total amount based on the required amount and surplus amount, set the amount of discharge of this total amount per hour for the above synchronization, and specify the opening of the three discharge ports to determine the amount distributed by the four-way valve.

[0043] Therefore, when the discharge rate of the total amount per hour is instructed to the operation control means via the operation panel, the operation control means causes the discharge means to discharge the mixture at the discharge rate per hour. On the other hand, when the distribution amount (distribution ratio) is instructed on the operation panel, the operation control means for controlling the operation of the four-way valve distributes the mixture supplied from the discharge means at the discharge amount per hour in the above-mentioned amounts and supplies it to the raw material supply means 20 and the third useful resource processing means.

[0044] The above will be explained below using specific numerical values. In the following explanation, it is assumed that 10 kg of secondary fermentation product is supplied per hour to the raw material supply means 20 and 5 kg per hour to the second useful resource processing means. In other words, the ratio of the amount of secondary fermentation product supplied to the raw material supply means 20 by the four-way valve 104 to the amount of secondary fermentation product supplied to the second useful resource processing means is 2:1.

[0045] Under normal circumstances, 15 kg of mixture is discharged per hour from the discharge means of the mixing means, and this is distributed in the above 2:1 ratio by the four-way valve, with ``2'' being supplied to the raw material supply means 20 and ``1'' being supplied to the second useful resource processing means.

[0046] emergency In this emergency (when the moisture content of the primary fermentation product exceeds a predetermined value (35%)), the amount of mixture supplied to the raw material supply means 20 is increased from the normal amount described above, but here we consider a case where the supply amount per hour is five times as much, or 50 kg. In this emergency, if the amount of mixture supplied to the third useful resource processing means is set to 0, the outlet side of the four-way valve facing the third useful resource processing means is closed, and the amount supplied to the raw material supply means 20 is set to 100%. Therefore, since the raw material supply means 20 operates at 50 kg per hour for five hours per day, a total of 250 kg per day is supplied with the mixture. As a result, in this emergency, the amount of raw material m per day will be 1,000 kg, and the amount of secondary fermented product (materials for adjusting raw materials) will be 250 kg. The moisture content of the raw materials supplied by conveyor 24 will be 74%, which is 8% less than normal, and the solid content will be more than 2.3 times higher, so the amount of microorganisms contributing to fermentation will also increase (because the microorganisms are supported by the secondary fermented product in the solid content and are roughly proportional to the amount of solid content). In an emergency, by increasing the amount of mixture (materials for raw material preparation) supplied to the raw material supply means 20 from normal levels, the moisture content of the raw material supplied to the primary fermentation treatment device 11 is reduced, while the amount of microorganisms contributing to fermentation is increased, thereby promoting fermentation more than normal and gradually returning the fermentation state (indicated by the moisture content value) of the primary fermented product discharged from the primary fermentation treatment device 11 to normal (normal: 35% or less). The amount of the mixture (materials for raw material preparation) supplied to raw material supply means 20 is preferably increased by 2 to 10 times, assuming that the normal amount is 1. The upper limit of this increase is determined taking into consideration the surplus space in fermentation treatment vessel 12 of primary fermentation treatment device 11 under normal conditions (since the amount of raw material input into fermentation treatment vessel 12 is 70 to 80%, there is 30 to 20% free space).

[0047] The storage section 84 is provided with an upper limit sensor and a lower limit sensor to monitor whether the amount of the secondary fermentation product stored therein (determined by the height of the upper surface) is appropriate. The upper limit sensor is connected to the operation control means of the discharge means and the operation control means of the three-way valve, and when the amount of secondary fermentation product stored in the storage section 84 exceeds a predetermined upper limit amount (when the top surface of the stored secondary fermentation product exceeds the upper limit level), it sends a signal S3 to the operation control means and the operation control means.

[0048] When the operation control means receives the signal S3, it activates the discharge means to discharge the stored secondary fermented product from the storage unit 84. When the operation control means receives the signal S1, it sets the four-way valve so that the secondary fermented product is distributed only to the supply passage side, and in this case, the secondary fermented product is supplied only to the second useful resource processing means.

[0049] The lower limit sensor is connected to the operation control means of the four-way valve, and sends a signal S4 to the operation control means when the amount of secondary fermentation product stored in the storage section 84 falls below a predetermined lower limit (when the upper surface of the stored secondary fermentation product falls below the lower limit level). Upon receiving the signal S4, the operation control means sets the four-way valve so as to increase the amount of primary fermentation product supplied to the first supply passage 40, thereby increasing the amount of secondary fermentation product stored in the storage section 84.

[0050] In the above, the raw material adjustment material, which is a material mainly used to adjust the moisture content of the raw material in the raw material supply means 20, has been described as a mixture of secondary fermentation product and carbonized product, but in the present invention, only the secondary fermentation product may be used as this raw material adjustment material.

[0051] As mentioned above, when using the mixture as a raw material preparation material, it is also important to use only the secondary fermentation product as the secondary fermentation product as needed to adjust the amount of microorganisms. This also applies when the mixture is used in a biological treatment tank for sewage treatment.

[0052] Heating the raw material supplied to the primary fermentation treatment device 11 is also effective in promoting the above-mentioned fermentation. An example of this will be described below with reference to Figure 2. Note that the sewage sludge recycling system shown in Figure 2 will be described with emphasis on the mechanism for the heating. Therefore, the secondary fermentation treatment device and related components are not shown in Figure 2, and the description of these components will be omitted in the specification.

[0053] A jacket 150 is arranged around the raw material hopper 22 so as to surround the raw material hopper with a gap between it and the outer wall of the raw material hopper, and a heated gas space 152 is formed through which heated gas passes to heat the organic waste that is the raw material inside the raw material hopper.

[0054] A heated gas passage 160 is provided extending from the discharge end 12b of the fermentation treatment vessel 12 to the heated gas space 152, for supplying exhaust gas generated as a result of fermentation in the fermentation treatment vessel from the fermentation treatment vessel to the heated air space as heated gas. An exhaust fan 162 is provided on the heated gas passage 160 on the other end 12b side of the fermentation treatment vessel 12 for discharging exhaust gas generated as a result of fermentation in the fermentation treatment vessel 12 to the outside of the apparatus.

[0055] Heating gas passage 160 is provided with heating means 170 for heating the exhaust gas passing therethrough. As described above, in the sewage sludge recycling system of the present invention, hyperthermophilic bacteria are used for fermenting organic waste, and therefore heating means 170 is provided to heat the dewatered sludge, which is the raw material, to promote fermentation, and to heat the heating gas in order to further reduce the moisture content of the dewatered sludge.

[0056] A heating means control means 172 is provided to control the operation of this heating means 170. Furthermore, in order for this heating means control means 172 to control the heating means 170 in accordance with its purpose, an exhaust gas temperature monitoring means 174 is provided in the heating gas passage 160 to detect and monitor the temperature of the heating gas flowing therethrough. Furthermore, a raw material temperature monitoring means 176 is provided in the raw material hopper 22 to detect and monitor the temperature of the raw material in the raw material hopper.

[0057] The moisture content sensor 44 installed in the fermentation treatment vessel 12 is also connected to the heating means control means 172, and a signal S1 is issued in an emergency when the moisture content of the primary fermentation product exceeds a predetermined value (35%), and is also sent to the heating means control means 172. The heating means control means 172 that has received the signal S1 operates the heating means 170 to heat the exhaust gas (heated gas) flowing through the heated gas passage 160 to 40° C. or higher and supply it to the heated gas space 152. As a result of the above, in an emergency, the raw material, which is dewatered sludge, is supplied with an increased amount of raw material adjustment materials (secondary fermentation product), which reduces its moisture content and increases the amount of microorganisms used for fermentation.Furthermore, the activity of the microorganisms is improved by the above-mentioned heating.As a result, fermentation is promoted, and the fermentation state (indicated by the moisture content value) of the primary fermentation product can be returned to normal (normal: 35% or less) even more quickly.

[0058] It is preferable that a heated gas inlet pipe 154 is connected to the heated gas space 152 for introducing the heated gas discharged from the heated gas space 152 into the upper space of the fermentation treatment vessel 12. This heated gas inlet pipe 154 allows the heated gas to be introduced into the upper space of the fermentation treatment vessel 12, where it can be heated to promote fermentation.

[0059] A temperature sensor 156 may be provided in the raw material hopper 22 to monitor the temperature of the raw material supplied. This temperature sensor 156 sends a signal to the operation control means 172 when the raw material temperature is below a predetermined value, regardless of the moisture content of the primary fermentation product, to activate the heating means 170, raising the temperature of the heating gas and thereby raising the temperature of the raw material. This heating helps to prevent the temperature of the dewatered sludge from dropping too low in winter, causing the raw material to be incompletely fermented or delayed, resulting in the above-mentioned emergency situation of the primary fermentation product.

[0060] In the sewage sludge resource recycling system 10 of the present invention, due to the above-mentioned configuration, in an emergency, the raw material, which is dewatered sludge, is supplied with an increased amount of raw material adjustment materials (mixture: secondary fermentation product + carbonized material), which reduces its moisture content and increases the amount of microorganisms used in fermentation, thereby promoting fermentation and allowing the system to quickly return to normal conditions. [Explanation of symbols]

[0061] 10 Sewage sludge recycling system 11 Primary fermentation treatment equipment 12 Fermentation vessel 15 Dehydrator 20 Raw material supply means 22 Raw material hopper 24 conveyor 30 Means of discharge 34 First allocation and supply means 80 Secondary fermentation treatment equipment 82 Manufacturing Department 84 Storage Unit 90 Second allocation supply means 100 Carbonization equipment 110 Mixing means 120 Third allocation supply means 130 Microbial activation device 200 Sewage treatment facilities 210 Biological treatment tank 212 Final Sedimentation Tank

Claims

1. A recycling-type sewage sludge recycling system that converts sewage sludge, which is organic waste, into useful materials. This recycling-type sewage sludge recycling system: a dehydration means for dehydrating the sewage sludge to a predetermined moisture content value to form a raw material; a primary fermentation treatment means having a horizontal cylindrical fermentation treatment vessel that rotates about a central axis, which rotates the fermentation treatment vessel about the central axis while gradually moving a raw material from an inlet end toward a discharge end within the fermentation treatment vessel over a predetermined number of days, and fermenting the raw material with aerobic microorganisms to produce a primary fermented product having a moisture content of not more than a first set value; a raw material supply means provided at the inlet end of the fermentation treatment vessel for receiving the raw material from the dehydration means and supplying the raw material into the fermentation treatment vessel; a primary fermentation product discharge means provided on the discharge end side of the fermentation treatment vessel for discharging the primary fermentation product outside the fermentation treatment vessel; a secondary fermentation treatment means for receiving the primary fermented product from the primary fermentation treatment means and subjecting the primary fermented product to additional fermentation to produce a secondary fermented product having a moisture content lower than that of the primary fermented product and not exceeding a second set moisture content value; a carbonization means for receiving the secondary fermented product from the secondary fermentation treatment means and carbonizing the same to produce a carbonized product; a mixing means for receiving the secondary fermented product from the secondary fermentation treatment means and the carbonized product from the carbonization means and mixing them to prepare a mixture; and a moisture content measuring means for measuring the moisture content of the primary fermentation product discharged from the primary fermentation product discharge means, A first allocating and supplying means is connected to the primary fermentation treatment means, and this first allocating and supplying means allocates the first fermented product to the secondary fermentation treatment means and to a first useful resource processing means for processing the remaining amount into a first useful product of a first form when the moisture content value of the primary fermented product measured by the moisture content measuring means is equal to or less than the first set moisture content value under normal circumstances, and supplies the entire amount of the primary fermented product to the secondary fermentation treatment means when the moisture content value exceeds the first set moisture content value under emergency circumstances. a second distributing and supplying means is connected to the secondary fermentation treatment means, and the second distributing and supplying means distributes and supplies at least a portion of the secondary fermented product to the carbonizing means and the mixing means, respectively; A third distribution supply means is connected to the mixing means, and this third distribution supply means is configured to distribute and supply at least a part of the mixture to the raw material supply means and / or a third useful resource processing means for processing the mixture into a third useful product of a third form. A recycling-type sewage sludge recycling system characterized by the following characteristics.

2. 2. The sewage sludge recycling system according to claim 1, wherein the secondary fermentation treatment means is one of a pile-up type using a compost shed, an open type using a rotary scoop agitator, and a closed agitator type using a composter.

3. 3. The sewage sludge resource recycling system of claim 2, wherein the aerobic microorganisms are gram-positive aerobic thermophiles, and the secondary fermentation treatment means is a deposition-type fermentation treatment means that deposits the primary fermented product supplied from the first distribution and supply means, and uses the deposited primary fermented product with the gram-positive aerobic thermophiles to produce a secondary fermented product with a second set moisture content that is lower than the first set moisture content of the primary fermented product, a storage section that stores the secondary fermented product produced in the production section, and a secondary fermented product discharge means that discharges a predetermined amount of the secondary fermented product from the storage section.

4. 2. The sewage sludge recycling system according to claim 1, wherein said third distributing and supplying means distributes and supplies said mixture to said raw material supplying means in said emergency.

5. 2. The sewage sludge recycling system of claim 1, wherein the third distribution supply means supplies a predetermined amount of the mixture to a biological treatment section of a sewage treatment facility in a state in which the aerobic microorganisms in the secondary fermentation product of the mixture have been activated via a microbial activation means.

6. 4. The sewage sludge recycling system according to claim 3, wherein the secondary fermentation treatment means includes a supply conveyor for supplying the primary fermented product supplied from the first distribution / supply means to the production section.

7. 4. The sewage sludge recycling system according to claim 3, wherein the secondary fermentation treatment means includes a transfer means for transferring the secondary fermented product produced in the production section from the production section to the storage section.

8. The sewage sludge resource recycling system of claim 3, wherein the production section of the secondary fermentation treatment means is equipped with a second moisture content measuring means for measuring the moisture content value of the produced secondary fermentation product, a transport and return means that is provided over almost the entire length of the production section and is capable of switching between a transport state in which the primary fermentation product is transported from the upstream side to the downstream side and a return state in which the secondary fermentation product is returned from the downstream side to the upstream side, and an operation control means that controls the switching between the transport state and the return state of the transport and return means in accordance with the moisture content value of the secondary fermentation product measured by the second moisture content measuring means.

9. The sewage sludge recycling system of claim 8, wherein the operation control means controls the transport and return means to switch to a return state when the moisture content value of the secondary fermentation product measured by the second moisture content measuring means exceeds the second set moisture content value.

10. 2. The sewage sludge recycling system of claim 1, wherein the first set moisture content value is 35% or less, and the second set moisture content value is set 2 to 15% lower than the first set moisture content value.

11. 2. The sewage sludge recycling system according to claim 1, wherein the mixture processed by the third useful resource processing means is a soil conditioner and compost / fertilizer.

12. 2. The sewage sludge recycling system according to claim 1, wherein said fermentation treatment vessel is provided with a stirring means for stirring the raw material therein.

13. 13. The sewage sludge recycling system according to claim 12, wherein the agitation means is a rotation actuation means for rotating the fermentation treatment vessel.

14. the raw material supply means has a raw material hopper for temporarily storing the raw material from the dehydration means, and the raw material hopper is surrounded by a jacket with a gap between the outer wall of the raw material hopper and the jacket to form a heating gas space through which a heating gas for heating the raw material in the raw material hopper passes; a heated gas passage extending from the discharge end of the fermentation treatment vessel to the heated gas space, for supplying exhaust gas generated as a result of fermentation in the fermentation treatment vessel from the fermentation treatment vessel to the heated gas space as heated gas; 2. The sewage sludge recycling system according to claim 1, comprising:

15. The sewage sludge recycling system according to claim 1, wherein the aerobic microorganisms include those belonging to the gram-positive Bacilli class of the Firmicutes phylum, and / or those belonging to the gram-positive Actinobacteria class of the Actinomycetes phylum, and / or those belonging to the gram-positive Chloroflexus phylum.

16. 16. The sewage sludge recycling system according to any one of claims 1 to 15, wherein the carbonization means is a carbonization means for producing activated carbon using the secondary fermentation product as a raw material.

17. The sewage sludge resource recycling system of claim 1, wherein the second distribution and supply means is capable of distributing and supplying at least a portion of the secondary fermentation product to the raw material supply means and / or a second useful resource processing means that processes the secondary fermentation product into a second useful product of a second type.

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