Algae cultivation system and method for cultivating algae

Abstract

To provide a system capable of culturing algae, which can supply a sufficient amount of CO2 according to the amount and growth of algae, and can also effectively utilize waste concrete, and a method therefor.SOLUTION: An algae culturing system 30A, 30B includes a storage 31, 53 that accommodates waste concrete 75 and culture water 82 for culturing algae, and a CO2 feeder 34 that supplies the culture water 82 in the storage 31, 53 with CO2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an improved cultivation system for cultivating photosynthetic algae. [Background technology]

[0002] In the past, efforts to capture and effectively utilize CO2 have been attracting attention in order to prevent global warming. One such effort that has attracted attention is microalgae culture, which can fix CO2 in algae cells during the algae cultivation process, as disclosed in Patent Document 1. It is thought that the cultured algae cells that fix CO2 can be used for various purposes, such as biofuels, chemical products, and aquaculture feed.

[0003] When cultivating algae, CO2 gas is dissolved in culture water to produce CO2-dissolved culture water, which is then replenished as needed in the algae culture device. By replenishing culture water with an increased CO2 content, the algae in the device can absorb sufficient CO2 during the growth process, and the CO2 is fixed in the algae bodies. By using algae bodies cultivated in this way, CO2 emissions can be reduced compared to when fossil fuels are used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-64577 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as the CO2 content of the culture water is increased to compensate for the increased CO2 required for algae proliferation and growth, the pH value gradually decreases, and the culture water becomes acidic. Meanwhile, algae prefer a neutral pH range and cannot survive in acidic culture water. To avoid acidifying the culture water, the invention described in Patent Document 1 limits the amount of CO2 supplied to prevent a decrease in the pH value of the culture water. As a result, there was a problem of insufficient CO2 supply.

[0006] Furthermore, conventionally, when cement was used, concrete waste materials such as waste concrete, waste sludge, waste lightweight aerated concrete (waste ALC) were generated. From the perspective of waste reduction, there was a demand for effective use of the concrete waste materials that were inevitably generated.

[0007] The present invention has been made to solve the above problems, and aims to provide a system and method for cultivating algae that can supply a sufficient amount of CO2 according to the amount and growth of algae and enable effective use of concrete waste. [Means for solving the problem]

[0008] The algae cultivation system of the present invention is characterized by comprising a storage device that stores waste concrete and culture water for cultivating algae, and a CO2 supply device that supplies CO2 to the culture water in the storage device.

[0009] In the algae cultivation system of the present invention, the algae are preferably cultivated in a storage device.

[0010] Furthermore, the concrete waste in the algae culture system of the present invention preferably includes granules that are crushed concrete waste, and the granules are granules from which fine particles smaller than a predetermined size have been removed.

[0011] Furthermore, the algae cultivation system of the present invention preferably has a separation device for separating particles contained in the culture water.

[0012] In addition, the concrete waste material in the algae culture system of the present invention preferably includes raw concrete sludge.

[0013] Furthermore, the waste concrete in the algae culture system of the present invention preferably includes waste concrete that has been exposed to CO2 and has adsorbed CO2.

[0014] Furthermore, in the algae culture system of the present invention, the CO2 is preferably derived from exhaust gas emitted from a factory.

[0015] In addition, in the algae cultivation system of the present invention, it is preferable that the waste concrete used for culturing the algae in the storage device is mixed with a cement mixture or reused as a roadbed material or the like.

[0016] In addition, in a cement factory equipped with the algae culture system of the present invention, the fine fraction is preferably used as a raw material for cement.

[0017] The method for cultivating algae of the present invention is characterized in that waste concrete and CO2 are supplied to culture water in which algae are cultivated.

[0018] In addition, in the method for cultivating algae of the present invention, the amount of waste concrete is preferably adjusted according to the growth of the algae to be cultivated.

[0019] In addition, in the method for cultivating algae of the present invention, it is preferable that the pH value of the culture water is adjusted to a predetermined range even when CO2 is dissolved. [Effects of the Invention]

[0020] The algae cultivation system of the present invention is equipped with a storage device that stores concrete waste and culture water, and a CO2 supply device that supplies CO2, so that the pH value can be adjusted to a range suitable for algae cultivation while supplying a sufficient amount of CO2 necessary for algae.

[0021] Furthermore, in the algae cultivation system of the present invention, the algae are cultivated in a storage device, so that the production of culture water and the cultivation of the algae are carried out in a single culture tank, which simplifies the device and saves space.

[0022] Furthermore, since the concrete waste in the algae cultivation system of the present invention has fine particles smaller than a predetermined size removed, it is easy to separate the algae from the concrete waste based on the difference in particle shape.

[0023] Furthermore, since the algae cultivation system of the present invention has a separation device, the algae used in the cultivation system can be separated from the concrete waste material.

[0024] Furthermore, the waste concrete in the algae cultivation system of the present invention contains lightweight aerated concrete or ready-mixed concrete sludge, which improves the productivity of algae cultivation and allows for the fixation of more CO2.

[0025] Furthermore, because the waste concrete in the algae cultivation system of the present invention is exposed to CO2 and absorbs CO2, it is possible to absorb more CO2 and fix CO2 in the waste concrete. Furthermore, even if the waste concrete contains a large amount of calcium hydroxide, this is reduced by carbonation, so it does not become excessively alkaline.

[0026] Furthermore, in the algae culture system of the present invention, the CO2 is derived from exhaust gas emitted from factories, so that the amount of CO2 emitted from factories can be reduced.

[0027] Furthermore, in the algae cultivation system of the present invention, the waste concrete used for algae cultivation in the storage device is reused as cement mixture or roadbed material, so that the waste concrete can be reused after use, thereby reducing waste materials.

[0028] Furthermore, in cement factories equipped with the algae cultivation system of the present invention, the fine fraction has a high calcium content and a low alkali metal content, so it can be used as a raw material for cement clinker, reducing waste materials.Furthermore, the fine fraction has a lower CO2 content than limestone, so CO2 emissions from the factory can be reduced.

[0029] The algae cultivation method of the present invention supplies waste concrete and CO2 to the culture water in which the algae are cultivated, so that the algae can be cultivated while maintaining the pH value in a range suitable for algae cultivation and providing a sufficient amount of CO2 necessary for the algae.

[0030] Furthermore, in the algae cultivation method of the present invention, the amount of waste concrete is adjusted according to the growth of the algae being cultivated, so that even if a sufficient amount of CO2 is supplied, the pH value of the culture water can be kept within a range suitable for algae growth.

[0031] Furthermore, in the method for cultivating algae of the present invention, the pH value of the culture water is adjusted to a predetermined range even when CO2 is dissolved, so that the pH value can be kept within a range suitable for algae growth. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic diagram showing a cement factory provided with an algae cultivation system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a front cross-sectional view showing the culture system of FIG. 1. [Figure 3] FIG. 10 is a front cross-sectional view showing a culture system according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing a cement factory according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram showing a cement factory according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] <First Embodiment> An algae culture system 30A according to a first embodiment of the present invention and a cement factory 10A equipped with the culture system 30A will be described with reference to FIGS. 1 and 2. FIG. 1 shows the cement factory 10A equipped with the algae culture system 30A according to the first embodiment of the present invention. FIG. 2 shows a front cross-sectional view of the culture system 30A shown in FIG. 1. The algae culture system 30A according to the first embodiment of the present invention is installed in the cement factory 10A, so that the CO2 required by the culture system 30A of the present invention can be continuously supplied from the factory's exhaust gas. As a result, the CO2 concentration in the exhaust gas from the cement factory 10A can be reduced.

[0034] 1 shows a cement plant 10A equipped with a culture system 30A. First, the cement plant 10A will be described. The cement plant 10A is composed of well-known equipment, including a raw material crusher 11, a preheater 12, a rotary kiln 13, a cooler 14, and a finishing crusher 15.

[0035] The raw material crusher 11 is a device that crushes and mixes the input cement clinker raw materials 72. The cement clinker raw materials 72 are well-known materials, such as limestone, clay, silica, and iron oxides such as copper tangles. The crushed cement raw materials 72 are heated while passing through a preheater 12, where they are mixed with ash from coal and waste materials used as the thermal energy source for cement burning. They are then sent to a rotary kiln 13 and burned. During this process, the raw materials undergo gradual chemical changes, forming lumpy clinker 73, which is a collection of hydraulic compounds. The formed clinker 73 enters a cooler 14 and is rapidly cooled. After cooling, the clinker 73 is placed in a finishing crusher 15 together with gypsum and cement admixtures and crushed into fine particles. The crushed material, crushed to a specified fineness, becomes cement 74.

[0036] In the first embodiment, concrete waste 75, such as waste concrete and waste ALC, is crushed in a crusher (not shown) and used to cultivate algae 71 in the cultivation system 30A. It is preferable that fine particles 76 of the crushed concrete waste 75, which are less than 1 mm in size, are fed into the raw material crusher 11 and used as cement clinker raw material 72. Furthermore, coarse particles 77, which are 1 mm to 5 mm in size, are used as granules 77 fed into the algae cultivation system 30A, as described below. The concrete waste 75 is a waste material containing cement hydrate, a calcium silicate material, and includes at least one of waste concrete materials such as waste concrete, waste ALC, ready-mixed concrete sludge, waste mortar, and waste cement paste. Among these, waste ALC and ready-mixed concrete sludge are preferred for concrete waste 75 because they contain less aggregate, have a high pH adjustment ability in the diatom cultivation tank, and can immobilize more CO2.

[0037] 2 shows an algae cultivation system 30A. The cultivation system 30A includes an algae cultivation tank 31, which is a storage device 31, a raw water supply device 32, a CO2 supply device 34, and an algae discharge device 41. The cultivation system 30A in the first embodiment is a single-tank cultivation system 30A that stores the algae 71 and culture water 82 for cultivating the algae 71.

[0038] In the algae culture tank 31, which is a storage device 31, culture water 82 is produced and algae 71 are cultured. One end 33 of a raw water supply device 32 is connected to the algae culture tank 31, and raw water 81, which is the source of the culture water 82, is poured into the algae culture tank 31. The raw water supply device 32 is a device that supplies the raw water 81, which is the source of the culture water 82. The other end (not shown) of the raw water supply device 32 is connected to a device that supplies the raw water 81. The raw water supply device 32 supplies raw water, i.e., salt water or fresh water depending on the algae to be cultured, to the algae culture tank 31. The raw water supply device 32 is a raw water supply pipe. The cement factory 10A is equipped with a chlorine bypass device (not shown) that prevents the preheater 12 from clogging, and an ash washing device 17 for waste incineration ash to be added to the cement raw material 72. The treated water generated in these devices is salt water containing nutrients, and is supplied as raw water 81 to the algae culture tank 31 via the raw water supply device 32.

[0039] One end 35 of a CO2 supply device 34 is connected to the algae culture tank 31. One end 35 of the CO2 supply device 34 is disposed within the algae culture tank 31 and immersed in raw water 81 supplied to the algae culture tank 31. The other end (not shown) of the CO2 supply device 34 is supplied with purified exhaust gas 78 generated within the cement factory 10A. High-concentration CO2 from the exhaust gas 78 generated within the cement factory 10A passes through the CO2 supply device 34 and is supplied to the algae culture tank 31. This allows the CO2 necessary for culturing the algae 71 to be dissolved in the raw water 81 injected into and stored in the algae culture tank 31, thereby producing culture water 82 for culturing the algae 71. The algae culture method of the present invention also includes supplying waste concrete 75 and CO2 to the culture water 82. Algae require an optimal pH range for the culture water 82, and the supply of CO2 is tailored to the type of algae, its growth rate, and other factors. Therefore, in the algae cultivation method of the present invention, algae are cultivated by supplying a sufficient amount of CO2 necessary for the algae while adjusting the pH value within a range suitable for algae cultivation. As will be described later, the algae cultivation method of the present invention includes a method in which the amount of waste concrete 75 is adjusted according to the growth of the algae, and the pH value of the culture water 82 is adjusted within a predetermined range.

[0040] The CO2 supplied to the CO2 supplying device 34 may be not only from the exhaust gas 78 generated and purified within the cement factory 10A, but also from CO2 prepared outside the cement factory 10A, placed in a storage container (not shown), and transported to the culture system 30A. That is, the CO2 supplied to the culture system 30A may be from a source other than the exhaust gas 78 generated within the cement factory 10A. In this case, the other end of the CO2 supplying device 34 is connected to a storage container containing CO2, and CO2 is supplied from the storage container. Excess gas supplied may be discharged through an outlet.

[0041] The algae culture tank 31 also has a settling tank 36 at the bottom of the algae culture tank 31, which collects the introduced granules 77. The settling tank 36 has a separator 37, an inner bottom surface 39, and an on-off valve 40.

[0042] The separator 37 is a plate-shaped sieve member with multiple holes 38 through which the introduced granules 77 pass. The separator 37 is disposed above the settling tank 36, and the introduced granules 77 pass through the multiple holes 38, sink, and accumulate in the settling tank 36. The separator 37 has a simple structure and accumulates the granules 77 at the bottom of the algae culture tank 31. The diameter of the multiple holes 38 is made to match the size of the introduced granules, and is a predetermined value between 1 mm and 5 mm. Note that the algae culture tank 31 does not necessarily need to be equipped with the separator 37. The inner bottom surface 39 of the settling tank 36 is gently inclined, concave downward toward the center of the settling tank 36. Therefore, the accumulated granules 77 naturally slide down toward the center of the settling tank 36. The collected granules 77 are separated into a fine particle fraction 79b containing a large amount of calcium carbonate and a coarse particle fraction 79a containing a large amount of aggregate. The former is reused as a cement mixture or concrete admixture, and the latter as aggregate or roadbed material, thereby making effective use of the waste material.

[0043] The granules 77 produced by crushing waste concrete 75 are calcium silicate-containing materials. Therefore, the culture water 82 produced by adding a predetermined amount of granules 77 maintains a weak alkaline pH. This allows the culture water 82 to have a higher CO2 content than when the granules 77 are not added to the culture water 82. Furthermore, the calcium silicate-containing material also supplies silicon, which affects algae. These waste concretes also immobilize CO2 by adsorbing carbon dioxide dissolved in the culture water 82. The amount of waste concrete 75 added is determined based on the type of waste concrete 75 (aggregate content), the type of algae being cultured, and the amount of culture. For example, the amount of granules 77 added is adjusted so that the concentration of granules 77 in the culture water 82 is 10,000 mg / L, 30,000 mg / L, 50,000 mg / L, etc.

[0044] An on-off valve 40 is provided in the center of the settling tank 36. The on-off valve 40 is closed when the granular material 77 is being stored. The on-off valve 40 is opened when the used granular material 77 is to be discharged for replacement or the like. As described above, the inner bottom surface 39 of the settling tank 36 is formed to gently slope toward the center of the settling tank 36, so that when the on-off valve 40 is opened, the granular material 77 falls naturally to the bottom of the settling tank 36. The on-off valve 40 may be an electromagnetic on-off valve.

[0045] The algae discharger 41 has an on-off valve 42, a drain port 43, a flange 44, and a filter 45. The algae discharger 41 is a device that discharges algae from the algae culture tank 31. The on-off valve 42 is fixed to one end of the algae discharger 41 on the side of the algae culture tank 31. The algae discharger 41 is a hollow pipe that connects one end to the other end, and the other end is a drain port 43. The flange 44 is provided midway between the one end and the other end of the algae discharger 41. The filter 45 is provided on the flange 44. The filter 45 filters the algae 71 in the culture water 82 that flows when the on-off valve 42 is opened. The filtered algae bodies of the algae 71 are dried and used as biofuel in the cement firing process.

[0046] The amount of CO2 required by algae increases as the growth of the algae progresses relative to the amount at the start of cultivation. Therefore, the optimal content of dissolved CO2 in the culture water 82 changes depending on the growth of the algae being cultured. Therefore, it is desirable to increase the amount of dissolved CO2 in the culture water 82 depending on the growth of the algae. One possible method for this is to periodically observe the growth of the algae, for example, by measuring at least one of the absorbance (turbidity) and pH value of the culture water 82, and then increasing the amount of CO2 supplied depending on the measured value. It is preferable to record in advance the optimal amount of CO2 or pH value depending on the growth of the algae, i.e., the absorbance (turbidity), for each growth level.

[0047] To carry out this method, it is also possible to configure the system to output at least one of absorbance (turbidity) and pH value and automatically control the amount of CO2 supplied to the CO2 supply device. An automatic CO2 supply control system can also be configured by providing an absorbance (turbidity) measuring device and / or pH value measuring device in the culture water 82, a CO2 supply rate adjusting device such as an electromagnetic valve in the CO2 supply device, and a control device that receives output from the absorbance (turbidity) measuring device and / or pH value measuring device to calculate the optimal amount of CO2 dissolved in the culture water 82 and control the CO2 supply rate adjusting device.

[0048] Alternatively, the growth rate of algae is largely determined by the algae. Therefore, instead of using an absorbance (turbidity) measuring device and / or a pH value measuring device, it is also possible to count the elapsed time or number of days since the start of cultivation and control the CO2 supply amount accordingly. An automatic CO2 supply amount control system can also be constructed by providing an elapsed time or number of days counting device, a CO2 supply amount adjusting device, and a control device that controls the CO2 supply amount adjusting device. In this case, maintenance of the absorbance (turbidity) measuring device and / or pH value measuring device placed in the culture water 82 is not required, and the system configuration can be simpler than the former.

[0049] The pH value of the culture water 82 with dissolved CO2 is adjusted to a suitable pH of around 7 by granules 77, which are a calcium silicate-containing material. The suitable pH value of the culture water 82 is in the range of approximately 6.2 to 7.5. The culture water 82 with dissolved CO2 and an adjusted pH is exposed to light 84, necessary for photosynthesis, and the algae 71 are cultivated. The wastewater 83 discharged from the algae culture tank 31 has nitrogen consumed by the diatoms and phosphorus adsorbed to the waste concrete, making wastewater treatment easy. The single-tank culture system 30A has the advantage of requiring only one type of tank compared to a two-tank system, saving space. Although the culture system in this example is a batch type, it may be a continuous type in which calcium silicate-containing material, culture water, etc. are constantly supplied. An agitator may be provided in the algae culture tank 31. The separation method is not limited to this, and may involve simultaneously discharging the calcium silicate-containing material and algae, and then separating them using a separate separation device such as sedimentation, cyclone, or sieving.

[0050] <Embodiment 2> An algae culture system 30B according to a second embodiment of the present invention will be described with reference to Figure 3. Figure 3 shows a front cross-sectional view of an algae culture tank 51 and a culture water production tank 53 of a culture system 30B corresponding to the culture system 30A of Figure 1. The algae culture system 30B according to the second embodiment of the present invention is a two-tank culture system including an algae culture tank 51 and a culture water production tank 53, which is a storage device 53. The second embodiment differs from the first embodiment in that it is a two-tank system including an algae culture tank 51 and a culture water production tank 53, and that it includes a culture water transfer device 54 for transferring the produced culture water. In the second embodiment, the same devices, components, and materials as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0051] The culture system 30B of the second embodiment includes an algae culture tank 51, a culture water production tank 53 serving as a storage device 53, a raw water supply device 32, a CO2 supply device 34, an algae discharge device 41, and a culture water transfer device 54.

[0052] One end 33 of the raw water supply device 32 is disposed in the culture water production tank 53. The raw water supply device 32 is a raw water supply pipe.

[0053] One end 35 of the CO2 supply device 34 is disposed in the culture water production tank 53 and is immersed in the raw water 81 supplied to the culture water production tank 53. The CO2 supply device 34 is a CO2 supply pipe.

[0054] The culture water generation tank 53 has a settling tank 36 at the bottom thereof for storing the introduced granules 77. The settling tank 36 has a separator 37, an inner bottom surface 39, and an on-off valve 40. The structures and functions of the settling tank 36, and the separator 37, inner bottom surface 39, and on-off valve 40 of the settling tank 36 are the same as those in the first embodiment. The algae culture tank 51 also has an algae discharger 41. The structure and function of the algae discharger 41 are the same as those in the first embodiment.

[0055] The culture water transfer device 54 is a device that transfers the culture water 82 produced in the culture water production tank 53, which is the storage device 53, to the algae culture tank 51 in which the algae 71 are cultured. One end 55 of the culture water transfer device 54 is disposed in the culture water 82 in the culture water production tank 53, and the other end 56 of the culture water transfer device 54 is disposed in the algae culture tank 51. A pump (not shown) that transfers the culture water 82 from the culture water production tank 53 to the algae culture tank 51 is disposed in the middle of the culture water transfer device 54. The culture water transfer device 54 is a culture water transfer pipe.

[0056] The pH value of the culture water 82 containing dissolved CO2 is adjusted to approximately pH 7, which is suitable for culturing algae 71, by calcium silicate-containing granules 77. The ideal pH value for the culture water 82 is in the range of approximately 6.2 to 7.5. The culture water 82, with dissolved CO2 and an adjusted pH, is exposed to light 84 necessary for photosynthesis, and the algae 71 is cultivated. Compared to the single-tank system, the two-tank culture system 30B has the advantage of being able to separate the culture water production tank 53 and the algae culture tank 51, making control easier and allowing for more efficient algae cultivation. The wastewater 83 discharged from the algae culture tank 31 has nitrogen consumed by diatoms and phosphorus adsorbed to waste concrete, making wastewater treatment easier.

[0057] <Third Embodiment> Referring to Figure 4, a cement factory 10B equipped with an algae cultivation system 30A according to a third embodiment of the present invention will be described. The cement factory 10B according to the third embodiment of the present invention is equipped with a methane fermentation facility 18 instead of the ash washing device 17 equipped in the cement factory 10A according to the first embodiment, and is also equipped with an adsorption tower 19. The algae cultivation system 30A is the same as the algae cultivation system 30A according to the first embodiment. The algae cultivation system 30B according to the second embodiment can also be selected. In the third embodiment, the same devices, components, and materials as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0058] In the third embodiment, concrete waste 75 is mixed with cement clinker raw materials 72 for effective utilization. Concrete waste 75, such as waste concrete, waste sludge, and waste ALC, is crushed in a crusher (not shown). Fine particles 76, each less than 1 mm in size, are fed into a raw material crusher 11 and used in cement production. Coarse particles 77, each 1 mm to 5 mm in size, are fed as granules 77 into an algae cultivation system 30A. The granules 77 are passed through an adsorption tower 19. Exhaust gas 78 from a cement factory 10B is supplied to the adsorption tower 19, and the granules 77 are exposed to CO2 in the adsorption tower 19 to adsorb CO2. Adjusting the moisture content of the granules 77 to a moisture content of 15% by mass or more and 60% by mass or less can improve the CO2 adsorption efficiency. In this case, it is possible to spray water on the granules 77 in the adsorption tower 19 or in a process preceding the adsorption tower 19. That is, the granules 77 are introduced into the algae culture tank 31 in a state where they have adsorbed CO2, so that the amount of CO2 in the exhaust gas from the entire cement factory 10B can be reduced. In particular, the raw concrete sludge contains a large amount of unhydrated cement and calcium hydroxide, and is therefore strongly alkaline. However, by exposing it to CO2, it becomes weakly alkaline, which prevents the diatom culture tank from becoming strongly alkaline and makes it easier to adjust the pH. In addition, the SO2 contained in the exhaust gas 78 X The CO2-containing gas from which acidic gases such as CO2 have been removed can be supplied to the algae culture tank 31.

[0059] The methane fermentation facility 18 generates biogas 86 using organic waste 85, such as sewage sludge and food waste, as a raw material. The material obtained in the methane fermentation facility 18 is used to manufacture cement in the cement factory 10B. The algae bodies of the algae 71 cultured and filtered in the culture system 30A and the biogas 86 containing methane gas recovered from the methane fermentation facility 18 are used as fuel for the cement factory. The methane fermentation residue 87 discharged from the methane fermentation facility 18 is separated into a solid fraction and a liquid fraction through a solid-liquid separation process in the dehydration device 20 of the methane fermentation facility 18. The solid fraction of the methane fermentation residue 87 is used as fuel for the cement factory. The liquid fraction of the methane fermentation residue 87 contains the nitrogen, phosphorus, and potassium contained in the organic waste 85 supplied as a raw material for methane fermentation, and serves as nutrients for algae cultivation. Therefore, the liquid portion of the methane fermentation residue 87 is salt water containing the above substances, and is supplied to the algae culture tank 31 as raw water 81. In other words, the gas, solid, and liquid portions obtained in the methane fermentation equipment 18 are effectively utilized for cement production and algae cultivation in the cement factory 10B, respectively. As for the wastewater 83 discharged from the algae culture tank 31, nitrogen is consumed by diatoms and phosphorus is adsorbed to the concrete waste, making wastewater treatment easy. Note that the methane fermentation residue 87 may be supplied to the algae culture tank 31 without being separated into solid and liquid portions, as long as this does not affect the algae cultivation.

[0060] <Fourth Embodiment> Referring to Figure 5, a cement factory 10C according to a fourth embodiment of the present invention, which is provided with an algae cultivation system 30A, will be described. The cement factory 10C according to the fourth embodiment of the present invention is provided with a methane fermentation facility 18 instead of the ash washing device 17 provided in the cement factory 10A according to the first embodiment, and also with an adsorption tower 19. The algae cultivation system 30A is the same as the algae cultivation system 30A according to the first embodiment. The algae cultivation system 30B according to the second embodiment can also be selected. In the fourth embodiment, the same devices, components, and materials as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0061] In the fourth embodiment, concrete waste 75 is mixed with cement clinker raw materials 72 for effective utilization. Concrete waste 75, such as waste concrete, waste sludge, and waste ALC, is crushed in a crusher (not shown). Fine particles 76, which are less than 1 mm in size, are fed into a raw material crusher 11 and used in cement production. Coarse particles 77, which are 1 mm to 5 mm in size, are fed as granules 77 into an algae cultivation system 30A. The granules 77 are passed through an adsorption tower 19. Biogas 86 generated in a methane fermentation facility 18 is supplied to the adsorption tower 19. The granules 77 are exposed to the biogas 86 within the adsorption tower 19, and CO2 and moisture contained in the biogas 86 are adsorbed. Adjusting the moisture content of the granules 77 to a range of 15% to 60% by mass can improve the CO2 adsorption efficiency. For example, water may be sprayed onto the granules 77 inside the adsorption tower 19 or in a process preceding the adsorption tower 19. The biogas 86 that has passed through the adsorption tower 19 is used as fuel for the cement factory 10C. That is, the methane gas in the biogas 86 is concentrated and supplied to cement production.

[0062] The granules 77 that have adsorbed CO2 and water are introduced into the algae culture tank 31. Note that as the granules 77 that have adsorbed CO2 pass through the adsorption tower 19, they are further classified into a fine particle group that adsorbs a large amount of CO2 and a coarse particle group that adsorbs a small amount of CO2, thereby further increasing the CO2 absorption efficiency of the entire system. The coarse particle group that has been exposed to the biogas 86 but has adsorbed a small amount of CO2 has a CO2 adsorption capacity remaining. By supplying the coarse particle group of the granules 77 that have been exposed to the biogas 86 and the exhaust gas 78 from the cement factory 10C to the algae culture tank 31, it is possible to fix more of the CO2 contained in the exhaust gas 78 from the cement factory 10C to the coarse particle group.

[0063] The methane fermentation facility 18 generates biogas 86 using organic waste 85, such as sewage sludge and food waste, as a raw material. The material obtained in the methane fermentation facility 18 is used in cement production in the cement plant 10C. The algae cells of the algae 71 cultivated and filtered in the cultivation system 30A and the biogas 86 containing methane gas recovered from the methane fermentation facility 18 are used as fuel for the cement plant. The methane fermentation residue 87 discharged from the methane fermentation facility 18 is separated into a solid and a liquid fraction through a solid-liquid separation process in the dehydration device 20. The solid fraction of the methane fermentation residue 87 is used as fuel for the cement plant. The liquid fraction of the methane fermentation residue 87 contains the nitrogen, phosphorus, and potassium contained in the organic waste 85 supplied as a raw material for methane fermentation, and serves as nutrients for algae cultivation. The liquid fraction of the methane fermentation residue 87 is saltwater and is supplied to the algae cultivation tank 31 as raw water 81. That is, the gas, solid, and liquid fractions obtained in the methane fermentation facility 18 are effectively utilized for cement production and algae cultivation, respectively, within the cement factory 10C. As for the wastewater 83 discharged from the algae cultivation tank 31, nitrogen is consumed by diatoms and phosphorus is adsorbed by the waste concrete, making wastewater treatment easy.

[0064] Next, the results of tests carried out on this embodiment will be described. Measurement test of the amount of waste ALC input, CO2 dissolution amount and pH value Waste ALC was crushed and added to saltwater, and CO2 gas was released and dissolved into the liquid while the amount of dissolved CO2 and pH were measured over time. As shown in Table 1, the amount of granules 77 made from waste ALC added was adjusted to 10,000 mg / L, 30,000 mg / L, and 50,000 mg / L. In addition, saltwater without any waste ALC added was prepared as reference water 1. The measurement results of this test are shown in Tables 2 and 3.

[0065] Implementation conditions Artificial seawater (Sigma sea salts 3% added) Crushed waste ALC (concrete waste material 75) into particles 77 with a particle size of 1 mm to 4 mm is poured into salt water. Dissolved by supplying CO2 gas (CO2 concentration 6%) at 0.5L / min Measure the amount of dissolved CO2 using a portable carbon dioxide concentration meter manufactured by Toa DKK

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] Measurement results and findings 1) The more waste ALC (concrete waste material 75) was added, the higher the concentration of CO2 dissolved in the water could be. 2) The CO2 concentration could be easily adjusted by adjusting the amount of waste ALC added. Therefore, the amount of CO2 required for algae growth could be supplied. 3) Even when the amount of dissolved CO2 was increased, the pH value of the culture water 82 could be adjusted to 7.1 to 7.2, which is suitable for algae cultivation. Therefore, it was found that additional pH adjustment was not necessary.

[0070] Measurement test of the amount of waste concrete added, CO2 dissolution amount and pH value Waste concrete was crushed and added to salt water, and while CO2 gas was released and dissolved in the liquid, the amount of dissolved CO2 and pH value were measured over time. The chemical composition of the waste concrete used is shown in Table 4. As shown in Table 5, the amount of waste concrete added was adjusted to 10,000 mg / L, 30,000 mg / L, and 50,000 mg / L. Salt water with no waste concrete added was also prepared as reference water 2. The measurement results of this test are shown in Tables 6 and 7.

[0071] Implementation conditions Artificial seawater (Sigma sea salts 3% added) -Particles with a particle size of 1.2mm to 5mm obtained by crushing waste concrete material are put into salt water. Dissolved by supplying CO2 gas (CO2 concentration 6%) at 0.5L / min Measure the amount of dissolved CO2 using a portable carbon dioxide concentration meter manufactured by Toa DKK

[0072] [Table 4]

[0073] [Table 5]

[0074] [Table 6]

[0075] [Table 7]

[0076] Measurement results and findings 1) The more waste concrete was added, the higher the concentration of CO2 dissolved in the water became. The CO2 concentration was lower than that of waste ALC. 2) The CO2 concentration could be easily adjusted by adjusting the amount of waste concrete added. Therefore, the amount of CO2 required for algae growth could be supplied. 3) Even with a high dissolved CO2 content, the pH value of the culture water 4 to 6 could be adjusted to 6.7 to 6.9, which is suitable for algae cultivation. Therefore, it was found that additional pH adjustment was not necessary.

[0077] Microalgae cultivation test using waste ALC Waste ALC was crushed and added to saltwater, and microalgae were cultivated using the method shown in Figure 2 while CO2 gas was released and dissolved in the saltwater. As shown in Table 1, the amount of waste ALC added was adjusted to 1,000 mg / L and 10,000 mg / L. The pH value of the saltwater and the growth rate of the algae using a turbidity measurement method were measured daily. In addition, saltwater containing no waste ALC or calcium silicate compounds was prepared as reference water 3. The measurement results of this test are shown in Tables 8 and 9.

[0078] Implementation conditions Artificial seawater (Sigma sea salts 3% added) - Waste ALC was crushed into granules with a particle size of 1mm to 4mm, which were then put into salt water, and KW21 (manufactured by ISC) was added as a nutrient salt. Dissolved by supplying CO2 gas (CO2 concentration 6%) at 0.5L / min Diatoms were added at an initial algal concentration of 1 x 10 5 Add to achieve cell / mL Standard water 3 was prepared by adding 64.8 mg of water glass as a silicate source to salt water that did not contain waste ALC. The growth of algae is measured by measuring the absorbance (turbidity) at a wavelength of 660 nm using a spectrophotometer.

[0079] [Table 8]

[0080] [Table 9]

[0081] Measurement results and findings 1) Under the above conditions, the pH value could be adjusted to 7.1 to 7.4, which is suitable for algae cultivation. Therefore, it was found that additional pH adjustment was not necessary. 2) In culture water 7-8, to which waste ALC was added, the culture promotion effect was about 1.5 times greater than that of control water 3, to which waste ALC was not added. In other words, test examples (1) to (3) proved that the main culture systems 30A and 30B, which add waste concrete materials 75 such as ALC and culture while dissolving CO2, have a clear effect on algae culture compared to when waste concrete materials 75 such as ALC are not added.

[0082] The algae cultivation system of the present invention is equipped with a storage device that stores concrete waste and culture water, and a CO2 supply device that supplies CO2, so that the pH value can be adjusted to a range suitable for algae cultivation while supplying a sufficient amount of CO2 necessary for algae.

[0083] Furthermore, the method for cultivating algae of the present invention includes a culture water production process in which concrete waste and culture water for cultivating algae are stored in a storage device to produce culture water, and a CO2 supply process in which CO2 is supplied to the culture water in the storage device.Therefore, algae can be cultivated by supplying a sufficient amount of CO2 necessary for the algae while maintaining the pH value in a range suitable for algae cultivation. [Explanation of symbols]

[0084] 10A, 10B, 10C Cement Factory 20 Dehydration equipment 30A, 30B Algae Cultivation System 31 Storage device, algae culture tank 51 Algae culture tank 53 Storage device, culture water generation tank 34 CO2 supply device 37 Separation device 72 Cement clinker raw materials 75 Concrete waste 76 Fine particles 77 Granules 78 Exhaust Gas 79a Coarse particles 79b Fine particles 82 Culture water

Claims

1. A storage device for storing concrete waste, algae, and culture water for culturing the algae; The culture water of the storage device is added to CO ２ Supplying CO ２ A system for cultivating algae comprising: The concrete waste material is a lightweight aerated concrete and / or a ready-mix concrete sludge. The concrete waste material includes pulverized concrete waste material having a size of 1 mm to 5 mm, The algae is cultured in the containment device; The pH of the culture water contained in the container is determined by the amount of the concrete waste and the CO ２ The amount of the culture system is adjusted to a range suitable for the growth of the algae.

2. The algae culture system according to claim 1, wherein the granules of 1 mm to 5 mm which are crushed concrete waste material contained in the concrete waste material are granules from which fine particles smaller than 1 mm in size, which are smaller than a predetermined size, have been removed.

3. The algae culture system according to claim 1 or 2, further comprising a separation device for separating the particulate matter contained in the culture water.

4. The waste concrete is CO ２ Exposed to CO ２ The algae culture system according to any one of claims 1 to 3, comprising waste concrete having adsorbed thereon.

5. The CO ２ is the CO2 emitted from exhaust gases from factories. ２ The algae culture system according to any one of claims 1 to 4.

6. A system for recycling waste concrete comprising the algae cultivation system according to any one of claims 1 to 5, and which reuses the waste concrete used for cultivating algae in the storage device as a cement mixture, a concrete admixture, an aggregate, or a roadbed material.

7. 3. A system for recycling fine particles comprising the algae cultivation system described in claim 2, and utilizing the fine particles removed from the crushed concrete waste material, which are smaller than the predetermined size and have a size of less than 1 mm, as a cement clinker raw material.

8. Concrete waste and CO ２ A method for culturing algae, comprising: supplying the above-mentioned mixture to a culture water for culturing algae, and culturing the algae. The concrete waste material is a lightweight aerated concrete and / or a ready-mix concrete sludge. The concrete waste material includes pulverized concrete waste material having a size of 1 mm to 5 mm, The pH of the culture water is determined by the addition of the waste concrete and the CO ２ The amount of the culture medium is adjusted to a range suitable for the growth of the algae.

Images