Circulation-type sewage sludge recycling system

Abstract

To provide a sewage sludge recycling system of a sealed type, capable of producing compost in a short period of time.SOLUTION: The sewage sludge recycling system comprises a dehydration means 15 of reducing the water content of sewage sludge to a predetermined feed stock water content, a primary product production means 11 of carrying out fermentation using an aerobic and thermophilic bacterium in a horizontal cylindrical fermentation container rotating on the center axis thereof for a predetermined number of days to produce a primary product of a water content of a first set water content or below, and a secondary product production means 82 of drying the primary product coming from the primary product production means using a circulation type sewage sludge recycling system comprising a primary product discharge means of discharging the primary product outside the fermentation treatment container to produce a secondary product of a water content lower than that of the primary product.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The Ministry of Land, Infrastructure, Transport and Tourism issued the following notice in National Water and Sewerage Planning No. 99 dated 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 "in the treatment of generated sludge, etc., efforts shall be made to reduce its volume by dehydration, incineration, etc., and to recycle the generated sludge, etc., as fuel or fertilizer." In light of the important issues facing Japan in achieving carbon neutrality by 2050 and shifting to domestic alternatives for production materials 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 Policy" (decided by the Headquarters for Strengthening Food Supply and Agriculture, Forestry and Fisheries Infrastructure on December 27, 2022) stated 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 usage (phosphorus base) will be expanded to 40%. In light of this background, and 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., and we ask that you fully understand this policy when carrying out your sewerage projects. Each prefecture is requested to inform the cities, towns and villages within their jurisdiction (excluding cities designated by government ordinance) of this information. Please note that this notice is technical advice based on the provisions of Article 245-4, Paragraph 1 of the Local Autonomy Law (Law No. 67 of 1947).

[0003] Known examples of equipment for recycling organic waste such as sewage sludge include a sewage sludge recycling system, which is a horizontal cylindrical fermentation vessel that ferments the organic waste material using aerobic hyperthermophilic bacteria (hereinafter sometimes referred to as hyperthermophilic bacteria), a raw material hopper provided at one end of the fermentation vessel for temporarily storing the organic waste material, raw material supplying means for supplying the raw material temporarily stored in the raw material hopper into the fermentation vessel, and a discharge means provided at the other end of the fermentation vessel for discharging the fermented raw material out of the fermentation vessel, and which rotates the fermentation vessel around its central axis to gradually move the raw material from one end to the other end of the fermentation vessel over a predetermined number of days while fermenting it, thereby recycling the organic waste into a resource, i.e., composting and fertilizer. This system is called a sealed sewage sludge recycling system (hereinafter referred to as a sealed composting apparatus).

[0004] In addition, 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 publication reads, "The publication 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 or during the 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 microbial activity, thereby producing fully-ripened compost from the solid waste; and a liquid fertilizer production device that produces liquid fertilizer using a portion of the fully-ripened compost produced by the decomposition and fermentation device and the liquid waste as raw materials. In addition, claim 2 limits the organic waste composting treatment system described in claim 1, and proposes an organic waste composting treatment system characterized in that the crushing and mixing device is equipped with a circulation mechanism for injecting the fully-ripened compost into the crushed solid waste and mixing it.

[0005] According to the organic waste composting treatment system described in claim 2, the circulation mechanism of the crushing and mixing device takes in a part of the fully matured compost into the device. The crushing and mixing device mixes the solid waste and the fully matured compost. Therefore, since the fully matured compost is returned by the circulation mechanism, decomposition and fermentation can be promoted without the need for a microbial introduction mechanism such as a culture medium. This allows the usage rate of the microorganisms used in the microbial introduction mechanism to be reduced, contributing to cost reduction.

[0006] According to the organic waste composting treatment system described in claim 2, the circulation mechanism of the crushing and mixing device takes in a portion of the fully matured compost into the device. The crushing and mixing device mixes the solid waste and the fully matured compost. As the fully matured compost is returned by the circulation mechanism, decomposition and fermentation can be promoted without the need for a microbial introduction mechanism such as a culture medium. This allows the usage rate of the microorganisms used in the microbial introduction mechanism to be reduced, which contributes to cost reduction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2005-320182 A 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, so that decomposition and fermentation can be promoted without the need for a microbial introduction mechanism such as a culture medium, and the utilization rate of microorganisms used in the microbial introduction mechanism can be reduced, which is expected to contribute to cost reduction. However, as described in the specification, it takes 30 to 90 days for the fully matured compost to become usable.

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

[0010] Therefore, the present invention aims to provide a sewage sludge resource recycling system that is based on the structure of the above-mentioned sealed 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 solving the above-mentioned problems of the sealed composting apparatus. [Means for solving the problem]

[0011] The above problems are solved by a sewage sludge resource recovery system having the following configurations (1) to (18). (1) A circulatory sewage sludge recycling system that converts sewage sludge, which is organic waste, into useful resources, comprising: a dehydration means for dehydrating the sewage sludge to a predetermined moisture content value to form a raw material; a primary product producing means for producing a primary product having a first set moisture content or less by gradually moving a raw material from one end to the other end of the fermentation treatment vessel over a predetermined number of days while rotating the fermentation treatment vessel about the central axis and fermenting the raw material with aerobic thermophiles; a raw material supplying means provided at one 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; and a primary product discharge means provided on the other end side of the fermentation treatment vessel for discharging the primary product to the outside of the fermentation treatment vessel; In a recycling-type sewage sludge recycling system, this sewage sludge recycling system is, a secondary product producing means for receiving the primary product from the primary product producing means and drying the primary product to produce a secondary product having a moisture content lower than a second set moisture content value; a first moisture content measuring means for measuring a moisture content value of the primary product discharged from the primary product discharge means; and a first distribution means for distributing a first predetermined amount of the primary product to the secondary product manufacturing means and a first useful resource processing means for processing the remaining amount into a first useful resource of a first form, when the moisture content value of the primary product measured by the first moisture content measuring means is normally equal to or less than the first set moisture content value, and for supplying the entire amount of the primary product to the secondary product manufacturing means when the moisture content value exceeds the predetermined primary product moisture content value; the secondary product manufacturing means comprises a receiving section provided at one end for receiving the primary product, a manufacturing section provided at least near the receiving section and having drying means for drying the primary product with drying means to manufacture a secondary product having a second set moisture content value lower than the first set moisture content value of the primary product, a storage section provided at the other end for storing the secondary product manufactured in the manufacturing section, and secondary product discharging means for discharging a predetermined amount of the secondary product from the storage section; The sewage sludge resource recovery system further includes a secondary product transport passage for transporting a predetermined amount of the secondary product from the secondary product discharge means to the raw material supply means. A sewage sludge resource recovery system comprising: (2) The sewage sludge resource recovery system according to (1), wherein the discharge amount of the secondary product discharged by the secondary product discharge means is switchable between a first discharge amount in the normal state and a second discharge amount in the emergency state, and the second discharge amount is 1 to 5 times the second discharge amount. (3) The sewage sludge resource recovery system according to (1) or (2), wherein during the production, the predetermined amount (weight per hour) of the secondary product transported to the raw material supply means is 2 to 10 parts by mass, assuming that the amount of dewatered sludge transported from the dehydrator to the raw material supply means per hour is 100 parts by mass. (4) The sewage sludge resource recovery system according to claim 1, wherein the production section of the secondary product production means is provided with a production section transport means for transporting the primary product from the receiving section to the storage section. (5) The sewage sludge resource recovery system according to (1), wherein the secondary product manufacturing means is provided with a secondary product transport means for transporting the secondary product manufactured in the manufacturing section from the manufacturing section to the storage section. (6) The sewage sludge resource recovery system according to claim (1), wherein the production section of the secondary product production means is equipped with a second moisture content measuring means for measuring the moisture content value of the produced secondary product, and a retention means for retaining the primary product in the production section until the moisture content value measured by the second moisture content measuring means becomes equal to or less than the second set moisture content value. (7) The sewage sludge resource recovery system according to (6), wherein the production section transport means can also function as the retention means by switching its operation. (8) The sewage sludge recycling system according to (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. (9) The sewage sludge resource recovery system according to (1), wherein the drying means is a blower. (10) The sewage sludge resource recovery system according to claim (1) is provided with a second useful resource processing means for processing the sludge into a second useful resource of a second form, and the secondary product transport passage does not include a second distribution means for enabling the secondary product from the secondary product manufacturing means to be supplied to the second useful resource processing means. (11) The sewage sludge resource recovery system according to (1) above, wherein the fermentation treatment vessel is provided with an agitation means for agitating the raw material therein. (12) The sewage sludge resource recovery system according to (1), wherein the stirring means is a rotation actuation means for rotating the fermentation treatment vessel. (13) The raw material hopper is surrounded by a jacket with a gap between the jacket and an outer wall of the raw material hopper to form a heating gas space through which a heating gas for heating the raw material in the raw material hopper passes; and a heating gas passage extending from the other end of the fermentation treatment vessel to the heating gas space and supplying exhaust gas generated in association with fermentation in the fermentation treatment vessel from the fermentation treatment vessel to the heating air space as heating gas; The sewage sludge resource recovery system according to (1) above, (14) The sewage sludge resource recovery system according to (13), wherein the heating gas passage is provided with a heating means for heating the exhaust gas passing therethrough. (15) The sewage sludge resource recovery system according to (14), further comprising a heating means operation control means for operating the heating means when the moisture content value of the primary product measured by the first moisture content measuring means exceeds the first set moisture content value. (16) The sewage sludge resource recovery system according to claim (13), wherein the raw material hopper is provided with a raw material temperature monitoring means for monitoring the temperature of the raw material in the raw material hopper, and when the temperature of the raw material falls below a predetermined value, the heating means operation control means operates the heating means to raise the temperature of the exhaust gas flowing through the heating gas passage. (17) The sewage sludge resource recovery system according to claim (14), wherein the heated gas passage is provided with an exhaust gas temperature monitoring means for monitoring the temperature of the exhaust gas flowing in the heated gas passage, and when the temperature of the exhaust gas is below a predetermined value, the heating means operation control means operates the heating means to raise the temperature of the exhaust gas flowing in the heated gas passage. (18) The sewage sludge resource recovery system according to (13), further comprising a first heated gas inlet pipeline for introducing the heated gas in the heated gas space into the fermentation treatment vessel. Effect of the Invention

[0012] The sewage sludge resource recycling system of the present invention focuses on the fact that the mature state of compost (fertilizer) is usually proportional to its moisture content, and that if this moisture content is below a specified value (usually 35%) the compost (fertilizer) can be said to be fully matured compost (fertilizer).When the moisture content of the primary product discharged from the primary product manufacturing means is lower than a specified value, that is, the primary product (compost) is determined to be fully mature, and the first allocation means divides the primary product into a useful resource (compost / fertilizer) and a material for raw material adjustment (the fully matured returned compost referred to in the aforementioned JP Patent Publication No. 2005-320182), and each is used effectively. In the present invention, a secondary product producing means is further provided to further dry the fully matured compost to produce a secondary product with a lower moisture content than the primary product, and this secondary product is used as a raw material adjustment material, which promotes the fermentation of the raw material. This secondary product can of course be used as compost or fertilizer. From the viewpoint of compost and fertilizer, the primary product has a higher moisture content than the secondary product and is therefore easier to process into pelleted fertilizer, etc., whereas the secondary product has a lower moisture content and is often in powder form, making it easier to commercialize as powdered fertilizer.

[0013] In addition, the present invention utilizes the first allocation means so that when the moisture content of the primary product exceeds the predetermined value, the primary product is not used at all as a useful resource (compost or fertilizer) and the entire amount is used for producing secondary products. This makes it possible to increase the stockpile of raw material adjustment (moisture content adjustment) materials and, in an emergency, increase the amount of raw material adjustment (moisture content adjustment) materials to be mixed with the raw materials, thereby further reducing the moisture content of the raw materials and promoting fermentation, thereby facilitating the return to normal.

[0014] In addition, in the sewage sludge resource recovery system of the present invention, sealed fermentation treatment vessels and treatment vessels for the secondary product production means can be used, which is effective in preventing pollution of the surrounding environment due to the flying of raw materials, primary products, and secondary products and the spread of odors. Therefore, the sewage sludge resource recovery system of the present invention is particularly effective when used in urban agriculture where fertilizer is produced on farmland. [Brief description of the drawings]

[0015] [Figure 1] 1 is a vertical cross-sectional view conceptually showing a sewage sludge resource recovery system according to an embodiment of the present invention. [Diagram 2] 2 is a vertical sectional view conceptually showing a modified example of the sewage sludge resource recovery system shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sewage sludge resource recovery system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0017] The sewage sludge recycling system 10 comprises a primary product manufacturing apparatus 11 having a horizontal cylindrical fermentation vessel 12 in which organic waste as a raw material is fermented by aerobic thermophilic bacteria, a raw material supplying means 20 provided at one end 12a of the fermentation vessel, and a discharge means 30 provided at the other end 12b of the fermentation vessel 12 as a discharge gate for discharging the primary product obtained by fermenting the raw material m out of the fermentation vessel. The raw material supplying means 20 and the discharge means 30 are controlled by an operation synchronizing means 140 so that their operations are synchronized.

[0018] 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 set in advance 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.

[0019] As shown in Fig. 2, the raw material hopper 22 is provided with a rotary stirring means 26 having a rotating shaft 26a extending vertically into the raw material hopper and a stirring member 26b such as a stirring blade attached to the rotating shaft 26a and extending horizontally, which rotates at a peripheral speed (for example, about 0.1 to 0.5 m / s) that does not cause the raw material to fly up or the odor to diffuse, thereby stirring the raw material. This stirring of the raw material allows the distribution of the moisture content in the raw material to be uniform.

[0020] As shown in Fig. 2, the fermentation treatment vessel 12 has a pair of fixed end plates 14 and 16 and a cylindrical fermentation treatment drum 18 rotatably attached between them around a central axis. The inner wall of the fermentation treatment drum 18 may be provided with a propelling blade (not shown). The fermentation treatment drum 18 is rotated by a rotary drive device (not shown), and the raw material fed into one end 12a is gradually moved toward the other end 12b over a predetermined number of days (for example, about 21 days) by the propelling blade while undergoing fermentation treatment, thereby turning the organic waste into resources, i.e., into compost and fertilizer. The movement of the raw material in the fermentation treatment vessel 12 may be caused by the pushing of the raw material by the conveyor 24.

[0021] The fermentation is carried out by aerobic thermophiles. According to the Biochemical Dictionary (4th Edition) published by Tokyo Kagaku Dojin Co., Ltd., thermophiles generally refer to bacteria that can grow at 55°C or higher, with thermophiles that can grow at 75°C or higher being called extreme thermophiles and bacteria that can grow at 90°C or higher being called hyperthermophiles. In the present invention, it is desirable to use bacteria (microorganisms) that are extreme thermophiles or higher. As the aerobic extreme thermophiles, for example, Thermus thermophilus can be used. By fermenting organic waste using such aerobic extreme thermophiles, for example, when the resource is converted into compost or fertilizer, plant seeds and pathogenic bacteria in the raw material that are harmful to plant growth can be decomposed and killed.

[0022] The sewage sludge resource recycling system 10 includes a secondary product manufacturing device 80 that receives the primary product from the primary product manufacturing device 11, dries it further, and manufactures a secondary product with a lower moisture content than the primary product. The primary purpose of this secondary product is to function as a material moisture content adjustment 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 product manufacturing device 80 is located on the primary product receiving side, and includes a manufacturing section 82 that processes the received primary product to manufacture a secondary product, and a storage section 84 that stores the secondary product manufactured in the manufacturing section 82. The structure will be described in detail later.

[0023] A discharge passage 32 for the primary product is connected to the discharge gate 30, and a distribution device 34 is provided at the downstream end of the discharge passage 32. The distribution device 34 is provided with a three-way valve 36 and an operation control means 38 for controlling the three-way valve 36. One of the discharge ports of the three-way valve 36 is connected to a first supply passage 40 for supplying a first set amount of the primary product to the secondary product manufacturing device 80 for processing the primary product into the secondary product, and the other discharge port is connected to a second supply passage 42 for supplying a second set amount of the primary product to a first useful resource processing means (not shown) for processing the primary product into a first useful resource. The secondary product manufacturing device 80 is provided with a supply conveyor 86, and the primary product from the first supply passage 42 is supplied to the manufacturing section 82 of the secondary product manufacturing device 80 by the supply conveyor 86.

[0024] 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 to adjust the distribution rate (distribution amount) of the primary product distributed by the three-way valve 36 when the primary product manufacturing apparatus 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.

[0025] A moisture content sensor 44 is disposed at the primary product discharge portion of the primary product manufacturing apparatus 11, for example, at the end where the discharge gate 30 of the fermentation treatment vessel 12 is provided as shown in FIG. 1, and this moisture content sensor 44 measures the moisture content of the primary product discharged from the fermentation treatment vessel 12 and outputs a signal S1 indicating the value to the operation control means 38.

[0026] The operation control means 38 judges whether the received signal S1 indicating the moisture content value of the primary product is below a predetermined moisture content value (for example, 35% indicating a predetermined fertilizer maturity level) or exceeds it (in an emergency), and in a normal state, controls the three-way valve 36 to distribute the primary product in the above ratio, while in an emergency, closes the second supply passage 42 side of the three-way valve 36 to supply the entire amount of the primary product to the first supply passage 40 side. As a result, if the primary product is not in a desired state as a first useful resource, it is not supplied to the first useful resource processing means. Therefore, according to the sewage sludge resource recovery system of this embodiment, defective useful resources are not distributed to the outside.

[0027] A dryer 88 consisting of, for example, a blower fan is provided on the side where the supply conveyor 86 of the production section 82 of the secondary product manufacturing apparatus 80 is provided (the primary product receiving side), and a conveying and returning means 90 consisting of a conveyor or the like is provided along almost the entire length inside the production section 82 (from the primary product receiving side to the secondary product discharging side). The primary product supplied to the secondary product manufacturing apparatus 80 is gradually dried by the air blown from the dryer 88 while being conveyed by the conveying and returning means 90, and becomes a secondary product having 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 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 / return means 90 is provided with an operation control means 92 for controlling switching between transport and return, setting of the transport speed, and the like.

[0028] The secondary product manufacturing apparatus 80 is provided with a transfer means 94 on the discharge side of the manufacturing section 82 for transferring the manufactured secondary product from the manufacturing section 82 to the storage section 84, and the operation of this transfer means 94 is controlled by an operation control means 96.

[0029] A moisture content sensor 93 is provided in a portion (downstream end) adjacent to the storage unit 84 of the production unit 82 of the secondary product production apparatus 80. This moisture content sensor 93 is for monitoring whether the primary product transported to the downstream end of the production unit 82 while being dried has a predetermined moisture content as the target secondary product. It measures the moisture content of the primary product (secondary product) at the downstream end of the production unit 82 and transmits a signal S2 indicating the moisture content value to the operation control means 92, 96.

[0030] The operation control means 92 that has received the signal S2 judges whether the moisture content value indicated by this signal S2 is equal to or lower than the predetermined moisture content value (30%) for the secondary product, and if the judgement is YES, keeps the conveying and returning means 90 in the conveying state. On the other hand, if the judgement is NO, the operation is switched to the returning state to return the primary product to the upstream side so that it is subjected to the action of the dryer 88 again, and the conveying and returning means 90 is switched to the conveying state. The above is repeated until the moisture content of the primary product falls below the predetermined moisture content for the secondary product.

[0031] On the other hand, the operation control means 96 which has received the signal S2 judges whether the moisture content value indicated by this signal S2 is equal to or lower than the predetermined moisture content value (30%) for the secondary product, and when the judgement is YES, it operates the transfer means 94 to transfer the manufactured secondary product to the storage section 84. On the other hand, when the judgement is NO, it does not operate the transfer means 94, and therefore the transfer of the incomplete product to the storage section 84 is not performed.

[0032] As described above, the secondary product stored in the storage section 84 is mainly used to function as a material for adjusting the moisture content of the raw material, but also acts to add aerobic thermophilic bacteria supported on the solid matter and functioning for fermentation to the raw material. For this reason, the storage section 84 is provided with a discharge means 99 for discharging the stored secondary product and an operation control means 99a for controlling its operation. The discharge means 99 is operated in synchronization with the dehydration means 15 by the synchronization means 142 via the operation control means 99a. The discharge amount of the secondary product by the discharge means 99 is set via the operation control means 99a at the amount set by the operation panel 108. In order to transport the above-mentioned secondary products, the sewage sludge resource recovery system 10 is provided with a raw material adjustment material transport path 100 for transporting the secondary products (raw material adjustment materials) from the secondary product manufacturing equipment 80 to the raw material supply means 20.

[0033] A distribution device 102 is provided on the raw material preparation material transport path 100. The distribution device 102 includes a three-way valve 104 and an operation control means 106 for controlling the three-way valve 104. One outlet of the three-way valve 36 is connected to a downstream portion of the raw material preparation material transport path 100 as a raw material preparation material, and the other outlet is connected to a supply passage 110 for supplying a second set amount of the secondary product to a second useful resource processing means (not shown) for processing the secondary product into a second useful resource. The second useful resource here refers to a drier powdered fertilizer (compost) or the like, since the moisture content of the secondary product as the raw material is set lower than that of the primary product.

[0034] Here, the operation of the discharge means 99 and the distribution device 102 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.

[0035] 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.

[0036] Normal time If 5 parts by mass of secondary product (materials for adjusting raw material (moisture content 30%)) is supplied to the raw material supplying means 20 for 100 parts by mass of the raw material (dewatered sludge), the secondary product supplied from the distribution device 102 to the raw material supplying 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 secondary product from the discharge means 99 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 secondary product discharged from the discharge means 99 is the sum of the required amount as a material for raw material adjustment and the surplus amount. The surplus is supplied through a supply passage 110 to a second useful resource processing means (not shown) for processing the secondary product into a second useful resource.

[0037] The setting of the total amount based on the required amount and the surplus amount, the setting of the discharge amount per hour of this total amount for the above-mentioned synchronization, and the indication of the opening degree of the two discharge ports for determining the distribution amount of the three-way valve 104 are performed by the operation panel 108.

[0038] Therefore, when the discharge amount per hour of the total amount is instructed to the operation control means 99a via the operation panel 108, the operation control means 99a causes the discharge means 99 to discharge the secondary products at the discharge amount per hour. On the other hand, when the allocation amount (allocation ratio) is instructed by the operation panel 108, the operation control means 106 which controls the operation of the three-way valve 104 allocates the secondary product supplied from the discharge means 99 at the discharge amount per hour in the above-mentioned amounts and supplies it to the raw material supply means 20 and the second useful resource processing means.

[0039] The above will be explained below using concrete values. In the following explanation, it is assumed that 10 kg of secondary products are supplied to the raw material supply means 20 per hour, and 5 kg of secondary products are supplied to the second useful resource processing means per hour. That is, the ratio of the amount of secondary products supplied to the raw material supply means 20 by the three-way valve 104: the amount of secondary products supplied to the second useful resource processing means is 2:1.

[0040] Then, under normal circumstances, 15 kg of secondary product is discharged per hour from the discharge means 99, which is distributed in the above-mentioned 2:1 ratio by the three-way valve 104, with "2" being supplied to the raw material supply means 20 and "1" being supplied to the second useful resource processing means.

[0041] emergency In this emergency (when the moisture content of the primary product exceeds a predetermined value (35%)), the amount of secondary product supplied to the raw material supplying means 20 is increased from the normal amount, but here, the amount of supply per hour is considered to be five times that amount, or 50 kg. In this emergency, if the amount of secondary product supplied to the second useful resource processing means is set to 0, the outlet side of the three-way valve 104 to the second useful resource processing means is closed, and the amount of supply to the raw material supplying means 20 is set to 100%. Therefore, since the raw material supplying means 20 operates at 50 kg per hour for 5 hours per day, a total of 250 kg of secondary product is supplied per day. As a result, in this emergency, the amount of raw material m per day will be 1,000 kg, and the amount of secondary products (materials for adjusting raw materials) will be 250 kg, the moisture content of the raw materials supplied by the conveyor 24 will be 74%, 8% less than under normal circumstances, and the solid content will be approximately 2.2 times higher, so the amount of microorganisms contributing to fermentation will also be approximately 2.2 times higher (because microorganisms are usually supported by solids and are roughly proportional to the amount of solids). In an emergency, by increasing the amount of secondary product (materials for raw material adjustment) supplied to the raw material supply means 20 more than usual, the moisture content of the raw material supplied to the primary product manufacturing equipment 11 is reduced while the amount of microorganisms contributing to fermentation is increased, thereby promoting fermentation more than usual and gradually returning the fermentation state (indicated by the moisture content value) of the primary product discharged from the primary product manufacturing equipment 11 to normal (normal: 35% or less). The increase in the amount of secondary product (materials for raw material adjustment) supplied to raw material supply means 20 is preferably 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 product manufacturing equipment 11 under normal circumstances (the amount of raw material put into fermentation treatment vessel 12 is 70 to 80%, so there is 30 to 20% space).

[0042] The storage section 84 is provided with an upper limit sensor 86 and a lower limit sensor 88 for monitoring whether the amount of the secondary product stored therein (determined by the height of the upper surface) is appropriate. The upper limit sensor 86 is connected to the operation control means 99a of the discharge means 99 and the operation control means 106 of the three-way valve 104, and transmits a signal S3 to the operation control means 99a and the operation control means 106 when the amount of the secondary product stored in the storage section 84 exceeds a predetermined upper limit amount (when the upper surface of the stored secondary product exceeds the upper limit level).

[0043] When the operation control means 99a receives the signal S3, it operates the discharge means 99 to discharge the stored secondary product from the storage unit 84. When the operation control means 106 receives the signal S1, it sets the three-way valve 104 so that the secondary product is distributed only to the supply passage 110 side, and at this time, the secondary product is supplied only to the second useful resource processing means.

[0044] The lower limit sensor 88 is connected to the operation control means 38 of the three-way valve 36, and transmits a signal S4 to the operation control means 38 when the amount of the secondary product stored in the storage section 84 falls below a predetermined lower limit amount (when the upper surface of the stored secondary product falls below the lower limit level). Upon receiving the signal S4, the operation control means 36 sets the three-way valve 36 so as to increase the amount of the primary product supplied to the first supply passage 40 side, thereby increasing the amount of the secondary product stored in the storage section 84.

[0045] Heating the raw materials supplied to the primary product manufacturing equipment 11 is also effective in promoting the above-mentioned fermentation. An example of this will be described below with reference to Fig. 2. Note that in the sewage sludge resource recovery system shown in Fig. 2, the above-mentioned heating mechanism will be mainly described. Therefore, the secondary product manufacturing equipment and its related parts and components are not shown in Fig. 2, and the description thereof will be omitted in the specification.

[0046] 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 heating gas space 152 is formed through which heating gas passes to heat the organic waste, which is the raw material in the raw material hopper.

[0047] A heated gas passage 160 for supplying exhaust gas generated as a result of fermentation in the fermentation treatment vessel to the heated air space as heated gas from the fermentation treatment vessel is provided so as to extend from the other end 12b of the fermentation treatment vessel 12 to the heated gas space 152. An exhaust fan 162 for discharging exhaust gas generated as a result of fermentation in the fermentation treatment vessel 12 to the outside of the apparatus is provided on the heated gas passage 160 on the other end 12b side of the fermentation treatment vessel 12.

[0048] The heated gas passage 160 is provided with heating means 170 for heating the exhaust gas passing therethrough. As described above, in the sewage sludge resource recovery system of the present invention, since hyperthermophilic bacteria are used for fermenting organic waste, the heating means 170 is provided for heating the dewatered sludge, which is the raw material, to promote fermentation, and for heating the heated gas for the purpose of further reducing the moisture content of the dewatered sludge.

[0049] A heating means control means 172 is provided to control the operation of this heating means 170. Also, in order for this heating means control means 172 to control the heating means 170 in accordance with the 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. Also, 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.

[0050] 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 product exceeds a predetermined value (35%), and is also transmitted to the heating means control means 172. The heating means control means 172 receiving the signal S1 operates the heating means 170 to heat the exhaust gas (heating gas) flowing through the heating gas passage 160 to 40° C. or higher and supply it to the heating gas space 152. As a result, in an emergency, the raw material, which is dewatered sludge, is supplied with an increased amount of raw material adjustment materials (secondary products), which reduces its moisture content and increases the amount of microorganisms used for fermentation, and further, the activity of the microorganisms is improved by the above-mentioned heating.As a result, fermentation is promoted, and the fermentation state of the primary product (indicated by the moisture content value) can be returned to normal (normal: 35% or less) even more quickly.

[0051] 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. The 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.

[0052] A temperature sensor 156 for monitoring the temperature of the supplied raw material may be provided inside the raw material hopper 22. 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 product, to operate the heating means 170 and raise the temperature of the heating gas to raise the temperature of the raw material. This heating helps to prevent the above-mentioned emergency state of the primary product from occurring in winter, etc., when the temperature of the dewatered sludge drops drastically and the fermentation of the raw material is incomplete or delayed.

[0053] In the sewage sludge resource recycling system 10 of the present invention, due to the above-mentioned configuration, in the event of an emergency, the raw material, which is dewatered sludge, is supplied with an increased amount of raw material adjustment materials (secondary products), which reduces its moisture content and increases the amount of microorganisms used in fermentation, promoting fermentation, so that the system can be quickly restored to normal conditions. [Explanation of symbols]

[0054] 10 Sewage sludge recycling system 11 Primary product manufacturing equipment 12 Fermentation vessel 15 Dehydrator 20 Raw material supply means 22 Raw material hopper 24 Conveyor 30 Means of discharge 34 Means of allocation 80 Secondary product manufacturing equipment 82 Manufacturing Department 84 Storage 102 Allocation methods

Claims

1. A circulatory sewage sludge recycling system that converts sewage sludge, which is organic waste, into useful resources, comprising: a dehydration means for dehydrating the sewage sludge to a predetermined moisture content value to form a raw material; a primary product producing means for producing a primary product having a horizontal cylindrical fermentation vessel that rotates around a central axis, the primary product producing means for producing a primary product having a first set moisture content or less by gradually moving a raw material from one end side to the other end side of the fermentation vessel over a predetermined number of days while rotating the fermentation vessel around the central axis and fermenting the raw material with aerobic thermophiles; a raw material supplying means provided at one 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; and a primary product discharge means provided on the other end side of the fermentation treatment vessel for discharging the primary product to the outside of the fermentation treatment vessel; In a recycling-type sewage sludge recycling system, this sewage sludge recycling system is, a secondary product producing means for receiving the primary product from the primary product producing means and drying the primary product to produce a secondary product having a moisture content lower than a second set moisture content value; a first moisture content measuring means for measuring a moisture content value of the primary product discharged from the primary product discharge means; and a first distribution means for distributing a first predetermined amount of the primary product to the secondary product manufacturing means and a first useful resource processing means for processing the remaining amount into a first useful resource of a first form, when the moisture content value of the primary product measured by the first moisture content measuring means is normally equal to or less than the first set moisture content value, and for supplying the entire amount of the primary product to the secondary product manufacturing means when the moisture content value exceeds the predetermined primary product moisture content value; the secondary product manufacturing means comprises a receiving section provided at one end for receiving the primary product, a manufacturing section provided at least near the receiving section and having drying means for drying the primary product with drying means to manufacture a secondary product having a second set moisture content value lower than the first set moisture content value of the primary product, and a storage section provided at the other end for storing the secondary product manufactured in the manufacturing section, and secondary product discharging means for discharging a predetermined amount of the secondary product from the storage section; The sewage sludge resource recovery system further includes a secondary product transport passage for transporting a predetermined amount of the secondary product from the secondary product discharge means to the raw material supply means. A sewage sludge resource recovery system comprising:

2. 2. The sewage sludge resource recovery system of claim 1, wherein the discharge amount of the secondary product discharged by the secondary product discharge means is switchable between a first discharge amount under normal conditions and a second discharge amount under emergency conditions, and the second discharge amount is 1 to 5 times the second discharge amount.

3. The sewage sludge resource recovery system of claim 1 or 2, wherein during the production, the specified amount (weight per hour) of the secondary product transported to the raw material supply means is 2 to 10 parts by mass, assuming that the amount of dehydrated sludge transported from the dehydrator to the raw material supply means per hour is 100 parts by mass.

4. 2. The sewage sludge resource recovery system according to claim 1, wherein the production section of the secondary product production means includes a production section transport means for transporting the primary product from the receiving section to the storage section.

5. 2. The sewage sludge resource recovery system according to claim 1, wherein said secondary product production means comprises secondary product transport means for transporting said secondary product produced in said production section from said production section to said storage section.

6. 2. The sewage sludge resource recovery system of claim 1, wherein the production section of the secondary product production means is equipped with a second moisture content measuring means for measuring the moisture content value of the produced secondary product, and a retention means for retaining the primary product in the production section until the moisture content value measured by the second moisture content measuring means becomes equal to or less than the second set moisture content value.

7. 7. A sewage sludge resource recovery system according to claim 6, wherein said production section transport means can also function as said retention means by switching its operation.

8. 2. The sewage sludge resource recovery system according to 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.

9. 2. The sewage sludge recycling system according to claim 1, wherein said drying means is a blower.

10. The sewage sludge resource recovery system of claim 1, further comprising a second useful resource processing means for processing the sewage sludge into a second useful resource of a second type, and the secondary product transport passage does not include a second distribution means for supplying a secondary product from the secondary product manufacturing means to the second useful resource processing means.

11. 2. The sewage sludge resource recovery system according to claim 1, wherein said fermentation treatment vessel is provided with an agitation means for agitating the raw material therein.

12. 2. The sewage sludge resource recovery system according to claim 1, wherein the agitation means is a rotation actuation means for rotating the fermentation treatment vessel.

13. The raw material hopper is surrounded by a jacket with a gap between the jacket and an outer wall of the raw material hopper to form a heating gas space through which a heating gas for heating the raw material in the raw material hopper passes; and a heating gas passage extending from the other end of the fermentation treatment vessel to the heating gas space and supplying exhaust gas generated in association with fermentation in the fermentation treatment vessel from the fermentation treatment vessel to the heating air space as heating gas; The sewage sludge resource recovery system according to claim 1, comprising:

14. 14. The sewage sludge resource recovery system according to claim 13, wherein said heated gas passage is provided with a heating means for heating the exhaust gas passing therethrough.

15. 15. A sewage sludge resource recovery system as claimed in claim 14, further comprising a heating means operation control means for operating the heating means when the moisture content value of the primary product measured by the first moisture content measuring means exceeds the first set moisture content value.

16. 14. The sewage sludge resource recovery system of claim 13, wherein the raw material hopper is provided with a raw material temperature monitoring means for monitoring the temperature of the raw material in the raw material hopper, and when the temperature of the raw material falls below a predetermined value, the heating means operation control means operates the heating means to raise the temperature of the exhaust gas flowing through the heating gas passage.

17. 15. A sewage sludge resource recovery system as claimed in claim 14, further comprising an exhaust gas temperature monitoring means for monitoring the temperature of the exhaust gas flowing through the heating gas passage, and when the temperature of the exhaust gas is below a predetermined value, the heating means operation control means operates the heating means to raise the temperature of the exhaust gas flowing through the heating gas passage.

18. 14. The sewage sludge resource recovery system according to claim 13, further comprising a first heated gas inlet pipe for introducing the heated gas in said heated gas space into said fermentation treatment vessel.

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