JP2006305467A - Recycling method of organic resources, and recycling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recycling method which can utilize a manure component contained in organic resources, and also contribute to an environment protection. <P>SOLUTION: A recycling apparatus 15 of the organic resources comprises an anaerobic fermentation tank 25 having a resource inlet 251 introducing the organic resources 21, a gas derivation mouth 253 deriving the produced biogas 23, and a digestive fluid derivation mouth 252 deriving the produced digestive fluid 22, and a floating grass cultivation tank 35 to which the digestive fluid 22 is introduced, and which cultivates floating grass. The apparatus may also have a dynamo 45 using the biogas 23 as fuel, and a heater 55 heating a cultivation liquid 351 using waste heat obtained by the dynamo 45. Further, the apparatus may also have a drying device 65 drying the floating grass to make dry grass. The electric power obtained by the dynamo 45, and/or the waste heat may be also used by the drying device 65. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recycling method and a recycling apparatus for organic resources such as activated sludge, and more particularly to recycling fertilizer components such as phosphorus compounds and nitrogen compounds and energy components such as carbon compounds contained in organic resources.

  In recent years, from the viewpoint of environmental protection and prevention of global warming, there is a strong demand for recycling by suppressing the release of all resources and thermal energy. Also in a sewage treatment facility, an activated sludge treatment method for treating and purifying organic components in sewage with microorganisms called activated sludge has been widespread. In this treatment method, consumption of chemical substances such as chemicals and energy is suppressed, but microorganisms grow and surplus activated sludge is produced. A part of the surplus activated sludge is dried and used as a powdered fertilizer, but most of the rest is currently incinerated. Incineration involves the dual problem of loss of useful resources and the release of wasted energy.

  As this partial solution, activated sludge is subjected to anaerobic fermentation, biogas containing methane and the like is taken out and supplied to a power generation system. For example, in the power generation method and power generation system disclosed in Patent Document 1, not only activated sludge, but also organic matter is subjected to anaerobic fermentation (methane fermentation) to generate digestion gas, and this is used as fuel to generate power. Recycling as energy.

  However, fertilizer components such as phosphorus and nitrogen remaining in the digestive juice produced by fermentation are not recycled and are released into rivers, lakes and the sea. The released fertilizer components eutrophicate rivers, lakes, and seas, causing sludge. As a method for removing the fertilizer component in the digestive juice, a method of removing phosphorus by reacting with iron and a method of removing the nitrogen component by digesting bacteria with nitrogen gas have been tried. These removal methods are effective in preventing eutrophication of rivers and the like, but do not actively and effectively recycle fertilizer components.

  On the other hand, in the domestic livestock industry, production prices have risen due to soaring feed and labor costs. One reason for this is that it is difficult to produce dry grass as feed. Many researches have been done to dry grass naturally, but it has not been successful in Japan. The reason why dry grass cannot be produced in Japan is that it does not become dry grass with high humidity. Overseas, grass that has grown sufficiently over a predetermined month and day is cut and dried as it is on the pasture. However, in Japan, where the humidity in the air is high, the ground of the pasture also contains a lot of moisture, and there are depressions with poor conditions. Therefore, it is very difficult to dry all the grass uniformly. Moist grass grows and decays and cannot be used as feed. There are rice straw and wheat straw as dry grass that does not rot in Japan. Although it is not known why it is difficult to rot, rice straw and wheat straw have a lot of silicon components and may be different from other plants.

  In Japan, as an alternative to dry grass, silage suitable for storage of moist grass is also available. Silage stores grass in a closed space with little oxygen, prevents rot by preventing the growth of miscellaneous bacteria by the acidity of lactic acid produced by lactic acid bacteria fermentation. Lactic acid bacteria fermentation requires a certain amount of moisture, and can use semi-drying grass that is a little dry on the spot, and is suitable for the Japanese climate. However, silage requires saccharides that can be used by lactic acid bacteria, and is difficult to apply to grasses with low saccharides.

Eventually, even when trying to dry grass naturally in Japan, moisture absorption is unavoidable due to high humidity, and the absorbed grass is rotted and cannot be used as feed. Conventionally, it was thought that using an artificial mechanical device for drying grass would not be economical.
JP 2002-275482 A

  The present invention has been made in view of the above background, and provides a recycling method and a recycling apparatus that can utilize fertilizer components contained in organic resources and contribute to environmental protection. Furthermore, the present invention provides a method and an apparatus for economically producing floating grass and dry grass by effectively using a product obtained by recycling.

  The organic resource recycling method of the present invention includes an anaerobic fermentation step in which an organic resource is subjected to anaerobic fermentation to obtain a biogas containing methane gas and a digestive fluid containing a fertilizer component, and at least a part of the obtained digested fluid is used. A floating grass cultivation process for cultivating floating grass as a fertilizer.

  In the organic resource recycling method of the present invention, energy components such as carbon contained in the organic resource are recovered as biogas containing methane gas in the anaerobic fermentation process. This biogas can be used as a fuel for the power generation process, as will be described later. On the other hand, the digestive juice obtained in the anaerobic fermentation process contains phosphorus compounds and nitrogen compounds, and these are useful as fertilizer components. This digestive juice can be used as a fertilizer for floating grass in the floating grass cultivation process. Therefore, according to the present invention, it is possible to effectively recycle both the energy component and the fertilizer component contained in the organic resource, and it is possible to contribute to environmental protection by eliminating the need to release the organic resource.

  The organic resource recycling method of the present invention includes a power generation step for generating electricity using the biogas as fuel, and a cultivation liquid heating step for heating the cultivation liquid used in the floating grass cultivation step using exhaust heat obtained in the power generation step. , May be included. The organic resource may be activated sludge, and the floating grass may be water hyacinth. Furthermore, you may include the drying process which dries the floating grass obtained at the floating grass cultivation process, and makes it dry grass. The power obtained in the power generation process and / or the exhaust heat may be used in the drying process.

  The components of biogas used in the power generation process depend on the fermentation conditions, but about 50% by volume ratio is methane gas and the remaining 50% is carbon dioxide. In addition to driving a prime mover, for example, this biogas can be used as household gas fuel for power generation. It can also be used as fuel for internal combustion engines such as diesel engines. Either biogas can be used as it is, or combustible gas such as methane gas or hydrogen gas can be separated and purified for use.

  Although activated sludge was shown as an example of an organic resource, it is in view of the current situation of surplus in sewage treatment facilities and being incinerated, and is not limited thereto. By accepting biomass (biological resources) in general, it is possible to stably secure recycled materials.

  Next, the grounds for selecting floating grass cultivation, especially water hyacinth as a fertilizer component, will be described. Floating grass grows when a plant consisting of roots, stems and leaves floats on the surface of the water, and grows when a sub-strain is split from the parent strain, and a new stem emerges and grows. For this reason, agricultural work such as sowing and replanting is not required. In addition, floating grass is useful as a feed for example as a whole plant, and does not harvest a part of fruit or fruit. Moreover, since the floating grass floats on the surface of the water, the growth and harvesting operations can be made into a flow operation by forming a flow in the cultivation liquid. Accordingly, it is easy in terms of cultivation technology to apply an automated cultivation apparatus to the floating grass cultivation process, and it can be expected from the viewpoint of economy.

  As the kind of floating grass, water hyacinth and button duckweed are preferable. Since both have strong fertility, a large yield can be expected, which is optimal for biomass production. Both are useful as livestock feed. In particular, water hyacinth is rich in crude protein and is excellent as a feed crop.

  Next, the use of exhaust heat obtained in the power generation process will be described. In this invention, the cultivation liquid heating process which heats the cultivation liquid used by a floating grass cultivation process using the waste heat obtained as a by-product of the electric power generation process which uses biogas as a fuel is employable. Thereby, since the cultivation liquid is heated to an appropriate temperature, floating grass can be cultivated throughout the year.

  In the floating grass cultivation process, it is important to manage the temperature of the cultivation environment and the temperature of the cultivation liquid. Many floating grasses such as water hyacinth and button duckweed are vulnerable to cold. For example, in the case of water hyacinth, it is from June to September that shows vigorous growth in the natural environment of Japan. Therefore, in order to cultivate throughout the year, it is necessary to take some cold measures from October to May. The first cold countermeasure is the greenhouse. When water hyacinth is cultivated in a greenhouse, water hyacinth flourishes vigorously in the vicinity of Kumano City in Mie Prefecture for 8 months from April to December. As the greenhouse, a glass greenhouse or a vinyl greenhouse using a vinyl film can be adopted.

  However, the countermeasures by the greenhouse are not enough, and the heating of the cultivation liquid by the exhaust heat of the present invention is effective as a second-stage countermeasure. By heating the cultivation liquid to about 15 ° C., the separation of water hyacinth child stocks is promoted. Furthermore, at 20 ° C., the stem grows and grows into long large leaves exceeding 50 cm above the surface of the water, and a new stem buds and grows as the stem grows.

  Heating measures to increase the air temperature in the greenhouse can be considered, but this is not effective because heat diffuses easily outside the greenhouse. Therefore, it is conceivable that the heating measure causes a deterioration in economic efficiency and cannot be realized as a business. Compared with this, the countermeasures for heating the cultivation liquid are large in the specific heat of the cultivation liquid, and the surface of the cultivation liquid is covered with floating grass so that the heat does not escape easily. Yes, it is preferable. In the vicinity of Kumano City, the temperature in the vinyl greenhouse reaches about 30 ° C at maximum, and the cultivation solution is maintained at about 10 ° C, even if the cultivation solution is not heated at all in winter in January and February. . Therefore, what is necessary is just to heat a cultivation liquid from 10 degreeC to 20 degreeC, and there is not much required calorie | heat amount.

  Next, the drying process will be described. In the drying step, for example, the floating grass may be dried by a mechanical drying device having a heat source, or natural drying may be performed. In the mechanical drying device, drying can be performed while continuously measuring the residual moisture content of the floating grass, and good dry grass having a predetermined moisture content or less can be obtained. In the present invention, since floating grass can be cultivated throughout the year, a large amount of dried grass can be obtained using a mechanical drying device throughout the year. For this reason, even if the apparatus itself is expensive, the unit cost of the drying cost of the floating grass is small, and it does not impair the economy. Moreover, the exhaust heat obtained by the above-mentioned power generation process can also be used for a drying process. For example, the exhaust heat of the generator can be transmitted to the machine drying device by a heat exchanger or the like. Furthermore, you may make it use the electric power itself obtained by a power generation process with a machine drying apparatus.

  Alternatively, a method may be used in which the floating grass is arranged on a mounting table in a greenhouse and naturally dried without having a heat source and not affected by rainfall or moisture on the ground.

  As described above, according to the recycling method of the present invention, the cost of fertilizer can be minimized by using the digestive juice obtained in the anaerobic fermentation process for the fertilizer of floating grass. Further, by heating the cultivation liquid using the exhaust heat obtained in the power generation process using biogas as fuel, it is possible to cultivate through the year and increase the equipment operation rate. Furthermore, exhaust heat can be used in the drying process. This exhaust heat is energy that has been discarded in the past, and by using it effectively, the economy is improved and it can also contribute to environmental protection. Moreover, by using these effective recycling methods in combination, even if the use of floating grass is for feed with a relatively low unit price, it is possible to perform economically attractive cultivation.

  A recycling apparatus for carrying out the above-described organic resource recycling method will be described below. The organic resource recycling apparatus of the present invention is anaerobic having a resource inlet for introducing organic resources, a gas outlet for extracting generated biogas, and a digester outlet for extracting generated digestive fluid. It has a fermentative fermenter and a floating grass cultivation tank in which the digestive juice is introduced and grows floating grass.

  An anaerobic fermentation tank is a tank that digests and decomposes organic substances into low-molecular compounds such as methane gas and carbon dioxide gas by the action of microorganisms such as methane bacteria. A conventionally well-known apparatus can be used as such an anaerobic fermenter. A low temperature fermenter of about 20 ° C., a medium temperature fermenter of about 30 ° C., and a high temperature fermenter of 50 to 60 ° C. are known. It is known that the higher the fermentation temperature, the faster the decomposition rate. Of course, the high-temperature fermenter is equipped with a heating device.

  It is preferable that the organic resources put into the anaerobic fermenter are finely pulverized because digestion and decomposition are promoted. For this reason, it is also possible to have a pulverizing means for pulverizing organic resources at the resource introduction port. In addition, the organic matter is partially decomposed by processes such as hydrolysis, oxidation, and acetic acid formation as a pre-process for digestion with methane bacteria. Therefore, the pretreatment tank which performs these pre-processes can also be provided in the upstream of an anaerobic fermentation tank. In this pretreatment tank, the fermentation process containing methane bacteria and the like is not used, and the pre-process can be completed by self-digestion of the organic resource itself.

  The floating grass cultivation tank is a pool-shaped tank having an upper end opening for holding a culture solution. Floating grass floats on the surface of the cultivation liquid, absorbs fertilizer components and water from the cultivation liquid, absorbs carbon dioxide in the atmosphere, and performs carbon dioxide assimilation with the energy of sunlight. As a result, floating grass grows, and also proliferates by making offspring and grandchild strains.

  It is preferable that the floating grass cultivation tank has a heating device for keeping the temperature of the cultivation liquid appropriately. The appropriate temperature depends on the floating grass to be cultivated, but for example, water hyacinth is 15 ° C or higher, more preferably about 20 ° C. Without a heating device, it will not be possible to grow floating grass in winter in Japan, making it difficult to grow throughout the year. Moreover, it is preferable that a floating grass cultivation tank is provided in a greenhouse. Since the temperature of air is maintained high by a glass greenhouse or a vinyl greenhouse, it is possible to suppress a decrease in the growth rate of floating grass due to a temperature decrease.

  The organic resource recycling apparatus of the present invention includes a generator using the biogas as a fuel, and a heating apparatus that heats the cultivation liquid held by the floating grass cultivation tank using exhaust heat obtained by the generator. May be. The output of the generator may be linked to a power transmission system of an existing electric power company, or may be connected to an electrical facility in the recycling apparatus, for example, a drying device or a lighting facility described later. If surplus power that cannot be used in the apparatus is sold through the power transmission system, biogas can be consumed stably. Moreover, it can apply also to a drying apparatus other than a heating apparatus as a use of waste heat.

  The organic resource recycling apparatus of the present invention may include a drying apparatus that dries the floating grass obtained in the floating grass cultivation tank to obtain dry grass. The drying device can be constituted by, for example, placing means, drying means, collection means, and roof means. The placing means is means for transferring the floating grass from the floating grass cultivation tank to the drying means. For example, a transfer conveyor device having an endless belt having a hook for hooking and transferring the floating grass can be used. The drying means is means for removing water from the floating grass and drying it, and a natural drying device or a mechanical drying device can be used. The former includes, for example, a drying conveyor device having an endless belt on which floating grass is placed and dried. The latter includes, for example, a hot air type drying apparatus. The roof means is a means for avoiding that the dry floating grass gets wet in the rain. For example, a roof portion such as a greenhouse may be used. The collecting means is means for collecting the dried grass obtained by drying the floating grass and transferring it to the next step such as packing, and for example, a collection box can be used.

  The organic resource recycling method of the present invention includes an anaerobic fermentation process in which an organic resource is subjected to anaerobic fermentation to obtain biogas and a digested liquid, and a floating grass cultivation process in which the digested liquid is used as a fertilizer. For this reason, the fertilizer component contained in the organic resource can be effectively recycled, and the release of the organic resource is unnecessary, which contributes to environmental protection. Furthermore, according to a method including a power generation process using biogas as fuel, a cultivation liquid heating process for heating the cultivation liquid with exhaust heat obtained in the power generation process, and a drying process for drying the floating grass, it is obtained by recycling. The product can be used effectively to produce floating grass and dry grass economically.

  Moreover, the recycling apparatus of the organic resource of this invention which has an anaerobic fermenter and a floating grass cultivation tank can implement | achieve the said recycling method. Furthermore, the organic resource recycling apparatus of the present invention having a generator, a heating device, and a drying device can realize economical production of the floating grass and the dried grass.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a process diagram showing a method for recycling activated sludge according to an embodiment of the present invention. In FIG. 1, each step is surrounded by a rectangle, and raw materials and products are surrounded by an ellipse, and a flow is indicated by an arrow. The activated sludge recycling method 1 of the embodiment is composed of anaerobic fermentation step 2, floating grass cultivation step 3, power generation step 4, cultivation liquid heating step 5, and drying step 6, for a total of five steps.

  In the anaerobic fermentation process 2, biogas 23 and digestive fluid 22 are generated by digesting and decomposing microorganisms such as methane bacteria using activated sludge 21, which is an organic resource, as a raw material. Energy components such as carbon contained in the activated sludge 21 are recovered in the biogas 23 mainly as methane gas. The digestive juice 22 contains fertilizer components such as phosphorus compounds and nitrogen compounds. Although the digestive juice 22 is used in the floating grass cultivation process 3, the surplus can also be supplied to the outside as liquid fertilizer by adjusting the concentration and adjusting the components.

  In the power generation process 4, the biogas 23 generated in the anaerobic fermentation process 2 is used as a fuel to generate power 41. As a power generation method, a general prime mover method in which biogas 23 is burned to obtain mechanical power may be used. In addition, a steam turbine system or the like may be used, and an appropriate power generation system can be set according to the facility scale. The obtained electric power 41 can be used for the drying process 6 or the like, or may be supplied to the outside. Waste heat 42 obtained as a by-product during power generation is used in the cultivation liquid heating step 5. For this reason, the overall efficiency of the power generation process 4 is high, which is preferable for environmental protection.

  In the cultivation liquid heating process 5, the cultivation liquid used in the floating grass cultivation process 3 is heated using the exhaust heat 42 obtained in the power generation process 4. The temperature of the heated cultivation liquid 51 is maintained at, for example, 15 ° C. or more, more preferably about 20 ° C. in the cultivation of water hyacinth. Note that the exhaust heat 42 does not have to be used in summer when the temperature is high.

  In the floating grass cultivation process 3, floating grass 32 is cultivated using the heated cultivation liquid 51 and digestive liquid 22. In the cultivation, the parent strain 31 as a base is necessary, but once the cultivation starts, the stock splitting proceeds, so that a regular work corresponding to sowing is unnecessary. Moreover, the work which replenishes the nutrient and water which are insufficient suitably is needed. A large amount of floating grass 32 that has been cultivated is harvested and supplied to the next drying step 6, and can also be shipped as feed.

  In the drying step 6, the harvested floating grass 32 is dried to produce dried grass 61. In drying, the electric power 41 and / or the exhaust heat 42 obtained in the power generation step 4 can be used, but natural drying may be used. The produced dry grass 61 can be shipped as a dry feed.

  An apparatus for performing the activated sludge 21 recycling method 1 shown in FIG. 1 is an activated sludge recycling apparatus 15 shown in FIG. The activated sludge recycling apparatus 15 includes an anaerobic fermentation tank 25, a pretreatment tank 26, a storage tank 75, a floating grass cultivation tank 35, a generator 45, a heating device 55, a drying device 65, and ancillary equipment.

  For the anaerobic fermenter 25, for example, a metal-made solid sealed tank 250 that is chemically stable and excellent in weather resistance can be used. A sludge inlet 251 for introducing activated sludge 21 is provided in the lower part of the side wall of the sealed tank 250, and a gas outlet 253 for leading out the generated biogas 23 is provided in the upper part of the side wall. The digestive fluid outlet 252 for extracting the digested fluid 22 is provided. Further, a discharge valve 254 is provided at the bottom of the sealed tank 250. Inside the closed tank 250 is provided means for supplying a fermented liquid containing methane bacteria and the like, the generated biogas 23 accumulates in the upper part of the closed tank 250, and the digested liquid 22 is separated above the organic sludge 21. It is like that.

  The pretreatment tank 26 is disposed adjacent to the anaerobic fermentation tank 25, and communicates with the sludge inlet 251 through the sludge inlet pipe 261 and the sludge inlet pump 262. An open tank 260 having an opening 263 on the upper side can be used for the pretreatment tank 26. The activated sludge 21 is introduced into the open tank 260 from the opening 263 and pretreated, and is then introduced to the anaerobic fermentation tank 25 by the sludge introduction pump 262.

  The storage tank 75 is disposed adjacent to the anaerobic fermentation tank 25, communicates with the gas outlet 253 through the gas outlet pipe 753, and communicates with the digestive juice outlet 252 through the digester outlet pipe 752. Yes. The storage tank 75 can be a robust sealed tank 750. The biogas 23 in the anaerobic fermentation tank 25 naturally flows in the gas outlet pipe 753 due to the pressure difference, moves to the storage tank 75, and is stored. Moreover, the digestive liquid 22 in the anaerobic fermenter 25 flows out from the supernatant liquid close to the digestive liquid outlet 252 in order, moves to the storage tank 75 through the digestive liquid outlet pipe 752, and is stored. Yes. In this embodiment, one storage tank 75 is commonly used, but a total of two storage tanks 75 may be provided for the biogas 23 and the digestive juice 22, respectively.

  The floating grass cultivation tank 35 is disposed in a greenhouse 352 adjacent to the storage tank 75. As the floating grass cultivation tank 35, a pool-like water tank 350 opened upward can be used. The cultivation liquid 351 is filled in the water tank 350, and the floating grass 32 to be cultivated floats on the liquid surface. Furthermore, a liquid fertilizer transfer pipe 353 is provided above the water tank 350 from the lower part of the side wall of the storage tank 75. A liquid manure introduction pump 354 and an on-off valve 355 are disposed in the middle of the liquid manure transfer pipe 353 so that an appropriate amount of the digestive juice 22 is supplied from the storage tank 75 to the floating grass cultivation tank 35. A more detailed configuration of the floating grass cultivation tank and examples of incidental devices will be described in the items of the examples.

  The generator 45 includes a prime mover 451 and a generator main body 452. The prime mover 451 communicates with the storage tank 75 via the gas transfer pipe 453 so that the biogas 23 is supplied as fuel. In the prime mover 451, the biogas 23 burns and heat energy is converted into mechanical energy. The prime mover 451 and the generator main body 452 are connected by a power transmission belt 454 or a common shaft, and mechanical energy is transmitted. In the generator main body 452, mechanical energy is converted into electrical energy to generate electric power 41, which is output from the output terminal 455. Most of the energy that could not be converted into electric power 41 by the generator 45 becomes exhaust heat 42. In order to recover the exhaust heat 42, a heat exchanger 456 is attached.

  The heating device 55 heats the cultivation liquid 351 and is provided below or in the vicinity of the floating grass cultivation tank 35. The heating device 55 and the heat exchanger 456 of the generator 45 are reciprocally connected by a heat transfer pipe 551. A heat transfer fluid reciprocates in the heat transfer pipe 551, and the exhaust heat 42 generated during power generation is transferred to the heating device 55. The transferred exhaust heat 42 is transmitted to the cultivation liquid 351 by the heating device 55 so that the liquid temperature rises. As the heat transfer fluid, a refrigerant liquid or water having a large specific heat and a small viscous resistance is used.

  The drying device 65 is disposed adjacent to the floating grass cultivation tank 35. The drying device 65 includes a transfer conveyor device 651, a drying conveyor device 652, a collection box 653, and a roof 654. The transfer conveyor device 651 includes a lower roller disposed in the cultivation liquid 351, an upper roller disposed in the atmosphere, a mesh-like endless belt that is inclined and stretched between the two rollers, It is formed with. The endless belt is rotated between rollers by a drive source (not shown) like a conveyor device. The drying conveyor device 652 is a conveyor that dries floating grass slowly in the horizontal direction. In this embodiment, the conveyors are arranged in four upper and lower stages and shifted left and right for each stage.

  The floating grass 32 is scooped out by the endless belt of the transfer conveyor device 651 from the state where it floats on the water surface of the cultivation liquid 351, as indicated by the dashed arrows in FIG. The floated grass 32 that has been scraped off is transferred toward the upper roller, falls over the upper roller, and is placed on the uppermost conveyor of the drying conveyor device 652. The floating grass 32 dries while slowly moving horizontally by the uppermost conveyor, and falls to the second stage at the end of the conveyor. The second-stage conveyor dries the floating grass horizontally while moving in the opposite direction, and finally the drying is completed in a process of reciprocating left and right in four stages. A collection box 653 is disposed at the lower end of the lowermost conveyor so that the dried floating grass 32 (that is, the dried grass 61) falls into the collection box 653 and is automatically collected. It has become. The roof 654 is arranged so as to avoid the dry floating grass 32 from getting wet in the rain.

  Note that the power 41 and / or the exhaust heat 42 of the generator 45 can also be used for drying the floating grass 32.

  The activated sludge recycling apparatus 15 according to the embodiment configured as described above operates as follows to recycle the activated sludge 21 and produces floating grass 32 and dried grass 61 as feed.

  First, the activated sludge 21 surplus in the sewage treatment facility is introduced from the opening 263 of the pretreatment tank 26. Then, pretreatment such as hydrolysis, oxidation, and acetic acid formation proceeds by self-digestion of the activated sludge 21. The activated sludge 21 for which the pretreatment has been completed is guided by the sludge introduction pump 262 to the sealed tank 250 of the anaerobic fermentation tank 25 through the sludge introduction pipe 261 and the sludge introduction port 251. In the sealed tank 250, a fermented liquid containing methane bacteria or the like is added to the activated sludge 21 and digestive decomposition proceeds to generate a biogas 23 and a digested liquid 22. The biogas 23 accumulates in the upper space of the sealed tank 250, and moves to the sealed tank 750 of the storage tank 75 from the gas outlet 253 through the gas outlet pipe 753 when the pressure increases. The digested liquid 22 also moves to the sealed tank 750 of the storage tank 75 through the digested liquid outlet 252 and the digested liquid outlet pipe 752 in order from the supernatant. The biogas 23 and the digestive fluid 22 are temporarily stored in the storage tank 75.

  On the other hand, the aquarium 350 of the floating grass cultivation tank 35 is filled with the cultivation liquid 351, and the parent strain 31 of the floating grass 32 to be cultivated is floated. Then, in order to replenish nutrients necessary for the growth and growth of the floating grass 32, the digestive juice 22 is applied as a liquid fertilizer. An appropriate amount of the digestive juice 22 is transferred from the storage tank 75 to the water tank 350 via the liquid fertilizer transfer pipe 353 by the liquid fertilizer introduction pump 354 and added to the cultivation liquid 351.

  On the other hand, the biogas 23 in the storage tank 75 is transferred to the prime mover 451 of the generator 45 through the gas transfer pipe 453. In the prime mover 451, the biogas 23 is burned as fuel to generate mechanical power. This mechanical power is transmitted to the generator main body 452 by a power transmission belt 454. In the generator main body 452, AC power 41 is generated based on the principle of electromagnetic induction and output from the output terminal 455. Most of the energy that has not been converted into electric power 41 by the generator 45 becomes exhaust heat 42 and is accumulated and recovered in the heat transfer fluid of the heat exchanger 456. The heat transfer fluid is transferred to the heating device 55 through the heat transfer pipe 551, and the exhaust heat 42 is transferred to the cultivation liquid 351 in the water tank 350. Thereby, the cultivation liquid 351 is heated.

  As described above, the digestive juice 22 is added to the cultivation liquid 351 of the floating grass cultivation tank 35 and heated. Furthermore, since the floating grass cultivation tank 35 is disposed in the greenhouse 352, the temperature is also kept warm. For this reason, the proliferation and growth of the floating grass 32 are promoted. A part of the grown floating grass 32 can be shipped as a feed as it is. Further, the remainder of the floating grass 32 is transferred to the drying device 65 except for the portion that becomes the next parent strain 31.

  In the drying device 65, the transfer conveyor device 651 is first operated, and the endless belt scoops the floating grass 32 in the cultivation liquid 351 and transfers it to the upper roller. The floating grass 32 falls over the upper roller and is placed on the drying conveyor device 652. Next, when the drying conveyor device 652 is operated, the floating grass 32 is dried by reciprocating two times on the left and right in order on the four-stage conveyor, and the dried grass 61 is produced. The dried grass 61 falls from the drying conveyor device 652 into the collection box 653 and is automatically collected and shipped as dried feed.

  As described above, according to the activated sludge recycling apparatus 15 of the embodiment, the activated sludge 21 surplus in the sewage treatment facility can be recycled and effectively used to produce floating grass 32 and dried grass 61 as feed. Furthermore, electric power 41 can also be generated.

  A more detailed configuration and ancillary equipment of the floating grass cultivation tank will be described with reference to FIGS. FIG. 3 is a bird's-eye view of the floating grass cultivation tank 85 of another embodiment of the present invention as viewed from above. The floating grass cultivation tank 85 includes a water tank 850, a guide wall 860, a harvesting means 870, and a liquid management device 880.

  The water tank 850 has a shallow box shape with an open bottom. The water tank 850 can also be provided on the sea surface L as shown in the vertical sectional view of the floating grass cultivation tank 85 of FIG. The water tank 850 on the sea surface L is composed of a frame 851 forming a side surface and a sheet 852 forming a bottom portion.

  The frame 851 floats on the sea surface L and surrounds the sea surface L in a rectangle. The frame 851 is composed of a strong frame body 853 having a rectangular cross section and a floating body 854 built in the frame body 853 and having an internal space, and has an overall specific gravity of less than 1. The cross-sectional shape of the frame 851 is not limited to a rectangle, but may be a circle or the like. A component member is not limited, and wood or a hollow resin having a specific gravity of less than 1 may be used.

  The sheet 852 covers the entire rectangular sea surface L surrounded by the frame 851. A peripheral edge portion of the sheet 852 is bent upward to form a box shape, and is fixed to the upper inside portion of the frame 851. As the sheet 852, a flexible and watertight rubber sheet or the like can be used. An appropriate amount of the cultivation liquid 351 is held inside the box-shaped sheet 852 of the water tank 850. Although the waterline of the water tank 850 moves up and down by the increase / decrease of the cultivation liquid 351, the peripheral edge of the sheet 852 is further above the upper limit of the waterline, and the intrusion of seawater is prevented.

  The guide wall 860 divides the liquid surface of the cultivation liquid 351 in the water tank 850 into a bent band shape having a predetermined width and extending from one end 861 to the terminal end 862 to form a liquid path. The liquid channel has a lower left corner in FIG. 3 as one end 861, extends in a zigzag shape toward the right and reaches the lower right corner, and then passes through the upper right corner and the upper left corner, and ends in the lower left corner. A harvesting means 870 is provided between the one end 861 and the end 862.

  In the water tank 850 that floats on the sea surface L, the guide wall 860 includes a floating head 863 that floats on the liquid surface of the cultivation liquid 351, and a wall 864 that hangs downward from the floating head 863 and is fixed to the bottom sheet 852. It has become. For the floating head 863, a hollow floating body, polystyrene foam, or the like can be used. For the wall portion 864, the same rubber sheet as the sheet 852 can be used. In addition, it is not necessary to adhere and fix between the lower part of the wall part 864, and the sheet | seat 852, and even if the cultivation liquid 351 comes and goes, it is accept | permitted.

  As shown in FIG. 3, the harvesting means 870 is provided at the lower left corner of the water tank 850 and is arranged so that the floating grass 32 guided to the end 862 of the liquid path formed by the guide wall 860 can be harvested. FIG. 5 is a vertical sectional view of the harvesting means 870. As shown in FIG. 5, the harvesting means 870 includes a box body 871, a lower roller 872, an upper roller 873, a drive source (not shown), an endless belt 874, and a transfer conveyor 875.

  The box body 871 is a box-shaped member that communicates with the end 862 of the liquid path of the cultivation liquid 351 and has water tightness with respect to seawater. The box 871 supports each member constituting the harvesting means 870 and incorporates a main part of a liquid management device 880 described later. The lower roller 872 is disposed in the cultivation liquid 351 in the box body 871, and the upper roller 873 is disposed in the atmosphere obliquely above the lower roller 872. The endless belt 874 is inclined and stretched between the two rollers 872 and 873. When an unillustrated drive source drives the upper roller 873, the upper roller 873 rotates to the right in the figure, and the endless belt 874 also rotates to the right in the figure between the rollers 872 and 873 like a conveyor. The drive source can be used for continuous use, periodic intermittent use, and use by any operation.

  The endless belt 874 is formed of a mesh-like member having a hole on one surface, and includes a large number of upstanding pins 876. The transfer conveyor 875 is a general belt conveyor for transferring articles, and is disposed on the upper surface of the box body 871, with one 877 suspended below the upper roller 873 and the other 878 suspended outside the water tank 850. .

  The liquid management apparatus 880 includes an intake port 881 for the culture liquid 351, a pump 882, a liquid feeding pipe 883, a fertilizer means 890, and a liquid guiding means 900. FIG. 6 is an explanatory diagram showing a main part of the liquid management device 880. The intake port 881 communicates with the bottom of the harvesting means 870 or the end 862 of the liquid path and can take in the cultivation liquid 351. The pump 882 takes in the cultivation liquid 351 from the intake port 881 and pumps it to the liquid supply pipe 883. A three-way valve 885 is provided in the middle of the liquid supply pipe 883 from the pump 882 so that the pressure destination can be switched between the water tank 850 and the discharge port 886. The discharge port 886 is for discharging the cultivation liquid 351 that has become excessive due to inflow of rainfall or the like.

  The fertilizer supply means 890 includes a fertilizer tank 891 and a fertilizer valve 892. The fertilizer tank 891 stores liquid fertilizer containing nutrients that cannot be replenished with the digestive juice 22 at a high concentration. The fertilizer valve 892 opens and closes between the fertilizer tank 891 and the liquid feeding pipe 883, and the liquid fertilizer flows into the cultivation liquid 351 by opening.

  The opening / closing operation of the liquid supply valve 885 and the fertilizer valve 892 and the on / off operation of the pump 882 may be performed manually or by an electric control device. When an electrical control device is used, it is preferable that the liquid supply valve 885 and the fertilizer valve 892 are electromagnetic valves, and a liquid level detection unit, a liquid quality detection unit, a flow detection unit, and the like are attached. These detection units can detect the level of the cultivation liquid 351, the nutrient concentration, and the flow state, and the cultivation liquid 351 can be managed under appropriate cultivation conditions by automatic control. In addition, you may make it reflect on control conditions, detecting and referring the temperature etc. which are concerned with cultivation conditions.

  For the liquid guiding means 900, a nozzle that ejects the cultivation liquid 351 is used. As shown in FIG. 3, a plurality of liquid guiding means 900 are provided in the bent portion of the liquid path formed by the guide wall 860, and the cultivation liquid 351 pumped from the pump 882 is in the liquid in the direction of the arrow or in the air. It is configured to erupt. As a result, the cultivation liquid 351 as a whole flows from one end 861 to the other end 862 of the liquid path, and the floating grass 32 can be guided to the harvesting means 870.

  Note that the liquid management device 880 may include a water supply tank or a fresh water generation device for compensating for the shortage due to evaporation of the cultivation liquid 351, and may be configured to communicate with the liquid supply pipe 883 via a valve. The water supply tank stores rainwater and can be installed on the sea surface adjacent to the water tank 850. Moreover, a fresh water production | generation apparatus is an apparatus which refine | purifies fresh water from seawater. By providing a water supply tank or fresh water generator, it can be applied to areas with low precipitation. Furthermore, the floating grass cultivation tank 85 on the sea level L may be provided with a breakwater that prevents splashing, a tethering device for anchoring to a specific point, a propulsion device for movement, and the like.

  In the floating grass cultivation tank 85 of the embodiment, a bent liquid path extending from one end 861 to the terminal end 862 is formed by the guide wall 860. Furthermore, a flow is formed in the cultivating liquid 351 by the liquid guiding means 900, and favorable cultivating conditions that are uniformized in the entire cultivating tank 85 are obtained. Thereby, the floating grass 32 can be efficiently and automatically cultivated, and can be smoothly guided to the harvesting means 870. Moreover, by providing the harvesting means 870, not only cultivation but also harvesting can be performed automatically, and productivity is extremely high. Furthermore, in the floating grass cultivation tank 85 on the sea surface L, the inner cultivation liquid 351 and the outer seawater are in dynamic balance, so that the water tank 850 can be formed with small mechanical strength. In addition, since there is no restriction on the installation site, it is easy to set an appropriate scale. Thus, the cultivation tank 85 is excellent in many respects.

It is process drawing which shows the recycling method of the activated sludge of the Example of this invention. It is explanatory drawing which shows the activated sludge recycling apparatus which enforces the recycling method of FIG. It is a bird's-eye view which shows the floating grass cultivation tank of another Example of this invention. FIG. 4 is a vertical sectional view of the embodiment of FIG. 3. It is a vertical sectional view showing harvesting means in the embodiment of FIG. It is explanatory drawing which shows the principal part of the liquid management apparatus in the Example of FIG.

Explanation of symbols

1: Recycling method of activated sludge 2: Anaerobic fermentation process
21: Activated sludge (organic resource) 22: Digestive liquid 23: Biogas 3: Floating grass cultivation process
31: Parent stock 32: Floating grass 4: Power generation process
41: Electric power 42: Waste heat 5: Cultivation liquid heating process 51: Heated cultivation liquid 6: Drying process 61: Dry grass 15: Activated sludge recycling device 25: Anaerobic fermentation tank 26: Pretreatment tank 35: Floating grass cultivation tank 45: Generator 55: Heating device 65: Drying device 75: Storage tank 85: Floating grass cultivation tank
850: Water tank 860: Guide wall
870: Harvesting means 880: Liquid management device

Claims (10)

An anaerobic fermentation process in which an organic resource is subjected to anaerobic fermentation to obtain a biogas containing methane gas and a digestive juice containing a fertilizer component;
Floating grass cultivation process for cultivating floating grass using at least a part of the obtained digestive juice as a fertilizer;
A method for recycling organic resources characterized by comprising:   The organic resource of Claim 1 including the electric power generation process which produces | generates electricity using the said biogas as a fuel, and the cultivation liquid heating process of heating the cultivation liquid used in the said floating grass cultivation process using the waste heat obtained by this electric power generation process Recycling method.   The organic resource recycling method according to claim 1 or 2, wherein the organic resource is activated sludge, and the floating grass is water hyacinth.   The recycling method of the organic resource of Claims 1-3 including the drying process which dries the said floating grass obtained at the said floating grass cultivation process and makes it dry grass.   The organic resource recycling method according to claim 1, wherein the electric power and / or the exhaust heat obtained in the power generation step is used in the drying step. An anaerobic fermentor having a resource inlet for introducing organic resources, a gas outlet for deriving generated biogas, and a digester outlet for deriving the generated digestive liquid;
A floating grass cultivation tank in which the digestive juice is introduced and cultivates floating grass;
A recycling apparatus for organic resources characterized by comprising:   The organic resource recycling apparatus according to claim 6, further comprising: a generator that uses the biogas as fuel; and a heating device that heats the cultivation liquid held by the floating grass cultivation tank using exhaust heat obtained by the generator. .   The organic resource recycling apparatus according to claim 6 or 7, wherein the organic resource is activated sludge, and the floating grass is water hyacinth.   The organic resource recycling apparatus according to claim 6, further comprising a drying device that dries the floating grass obtained in the floating grass cultivation tank to obtain dried grass.   The organic resource recycling apparatus according to any one of claims 6 to 9, wherein the electric power obtained by the generator and / or the exhaust heat is used in the drying apparatus.

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