Wastewater treatment apparatus and wastewater treatment method

Abstract

To treat colored wastewater using low-cost biotreatment.SOLUTION: A wastewater treatment device which treats wastewater including an organic chromaticity component comprises a treatment mechanism which treats the wastewater with an enzyme produced by Bacillus Proteolyticus. The treatment mechanism has a reaction vessel which allows the enzyme to react with the organic chromaticity component in the wastewater.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a wastewater treatment apparatus and a wastewater treatment method.

Background Art

[0002] In developing countries, the treatment of colored wastewater is a problem. The dye components contained in colored wastewater are hardly decomposable organic substances and the like. Further, even when the colored wastewater containing the dye component satisfies the discharge standard, the chromaticity is high when visually confirmed, and it is often misrecognized as not being appropriately treated. For this reason, a higher decomposition rate is required for the dye components in the colored wastewater.

[0003] In addition, for example, physicochemical treatment methods such as coagulation treatment, ozone treatment, or electrolysis treatment are known. However, in these physicochemical treatment methods, the running cost becomes high. For this reason, there is a current situation where it is difficult to adopt in developing countries.

[0004] On the other hand, biological treatment methods such as activated sludge treatment are widely adopted for the treatment of ordinary organic wastewater because they are relatively low in cost. However, in biological treatment methods, it is difficult to decompose hardly decomposable dye components as described above. Among them, azo dyes are known to be difficult to biodegrade.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a wastewater treatment apparatus and a wastewater treatment method capable of treating colored wastewater by low-cost biological treatment.

Means for Solving the Problems

[0007] The wastewater treatment apparatus according to the embodiment is a wastewater treatment apparatus for treating wastewater containing an organic chromaticity component, and includes a treatment mechanism for treating the wastewater with an enzyme produced by Bacillus Proteolyticus. The organic chromogenic component is an azo dye, and the enzyme decomposes at least a part of the azo bond of the azo dye. 。

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0009] The present inventors have discovered a new function of Bacillus Proteolyticus belonging to the genus Bacillus, namely, the ability to decompose dyes. The embodiments described below relate to wastewater treatment using the dye-decomposing ability of Bacillus Proteolyticus.Bacillus proteolyticus described in this specification is described as having a preservation number (NBRC number) 113920 in the catalog issued by the National Institute of Technology and Evaluation, Biotechnology Center (NBRC: NITE Biological Resource Center), and was freely available for transfer before the filing of the application.

[0010] [Embodiment 1] Embodiment 1 will be described with reference to the drawings.

[0011] (Configuration Example of Wastewater Treatment Apparatus) FIG. 1 is a diagram showing an example of the configuration of a wastewater treatment apparatus 100 according to Embodiment 1. The wastewater treatment apparatus 100 treats wastewater, which is water to be treated, and discharges it outside the wastewater treatment apparatus 100 as treated water that has been treated. The wastewater to be treated by the wastewater treatment apparatus 100 is, for example, colored wastewater containing an organic chromaticity component. The organic chromaticity component is, for example, an azo dye containing an azo bond (-N=N-).

[0012] As shown in FIG. 1, the wastewater treatment apparatus 100 of Embodiment 1 includes a primary sedimentation tank 11, a reaction tank 12, a final sedimentation tank 13, and a control unit 60. In FIG. 1, the primary sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13 are arranged horizontally, but the primary sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13 may be arranged with a gradient such that the arrangement positions become lower in this order. Thereby, the water to be treated can flow down naturally from the upstream primary sedimentation tank 11 to the downstream final sedimentation tank 13.

[0013] The primary sedimentation tank 11 temporarily stores the water to be treated that flows into the wastewater treatment apparatus 100. Thereby, the relatively heavy suspended substances contained in the water to be treated can be precipitated as sludge or the like in the primary sedimentation tank 11 and separated from the water to be treated. Note that a sludge discharge pipe (not shown) for discharging the precipitated sludge is provided at the bottom of the primary sedimentation tank 11.

[0014] The supernatant of the water to be treated from which the suspended substances have been separated is sent to the subsequent reaction tank 12.

[0015] The reaction tank 12 is a water tank equipped with a mechanism for decomposing and removing organic chromatic components in the water to be treated by the action of Bacillus proteolyticus. The reaction tank 12 includes, for example, a plurality of compartments 12a to 12d. These compartments 12a, 12b, 12c, and 12d are arranged in this order from the upstream side to the downstream side. However, the number of compartments 12a to 12d provided in the reaction tank 12 is arbitrary.

[0016] In addition, in the configuration of Embodiment 1, the reaction tank 12 is included in the treatment mechanism for treating wastewater by Bacillus proteolyticus. An aeration facility (blower 31, air supply pipe 41, valve 51, and diffuser plate 32) and a return facility (return pipe 42 and pump 21) described later may be included in the treatment mechanism.

[0017] The wastewater treatment apparatus 100 is provided with an aeration facility for aerating the water to be treated in the reaction tank 12. The aeration facility includes a blower 31, an air supply pipe 41, a valve 51, and a plurality of diffuser plates 32 (32a to 32d).

[0018] The blower 31 sends a gas such as air to the diffuser plate 32 through the air supply pipe 41. One end of the air supply pipe 41 is connected to the blower 31. The other end of the air supply pipe 41 branches into a plurality and is connected to the plurality of diffuser plates 32 respectively. The plurality of diffuser plates 32a to 32d are respectively arranged in the plurality of compartments 12a to 12d of the reaction tank 12. A valve 51 is provided in the air supply pipe 41, and by opening and closing this valve 51, the sending of the gas from the blower 31 to the diffuser plate 32 is started and stopped.

[0019] With such an aeration facility, the gas from the blower 31 is supplied to each of the compartments 12a to 12d. By supplying gas to the reaction tank 12 into which Bacillus proteolyticus has been introduced, the reaction between the enzyme of Bacillus proteolyticus and the organic chromatic component is promoted by the oxygen contained in the gas such as air.

[0020] The final sedimentation tank 13 temporarily stores the water to be treated flowing out from the reaction tank 12. Thereby, the suspended substances remaining in the water to be treated can be precipitated as sludge or the like and separated from the water to be treated. A sludge discharge pipe 43 is provided at the bottom of the final sedimentation tank 13. A pump 22 is provided in the sludge discharge pipe 43 to discharge the surplus sludge precipitated at the bottom of the final sedimentation tank 13 outside the wastewater treatment apparatus 100.

[0021] The final sedimentation tank 13 is also provided with a return facility for returning a part of the water to be treated to the reaction tank 12. The return facility includes a return pipe 42 and a pump 21. One end of the return pipe 42 is connected to the final sedimentation tank 13, and the other end is connected to, for example, the most upstream section 12a of the reaction tank 12. A pump 21 is provided in the return pipe 42.

[0022] With such a return facility, a part of the water to be treated stored in the final sedimentation tank 13 is returned to the upstream part of the reaction tank 12 and subjected to multiple treatments. Note that the above-described sludge discharge pipe 43 is connected to the return pipe 42. Thereby, the mixing of surplus sludge into the water to be treated returned to the reaction tank 12 is suppressed.

[0023] The supernatant water of the water to be treated from which the remaining suspended substances have been separated in the final sedimentation tank 13 is discharged from the final sedimentation tank 13 as treated water.

[0024] Disinfection equipment (not shown) is provided on the downstream side of the final sedimentation tank 13. The treated water discharged from the final sedimentation tank 13 is disinfected in the disinfection equipment and discharged into a river, the ocean, or the like.

[0025] The control unit 60 is configured as a computer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and controls each part of the wastewater treatment apparatus 100. That is, the control unit 60 controls the start and stop of the operation of the blower 31 and the pumps 21 and 22, and also controls the opening and closing of the valve 51.

[0026] Further, the control unit 60 may receive a signal from a sensor (not shown) provided in the primary sedimentation tank 11 and monitor the concentration of the organic chromaticity component contained in the water to be treated stored in the primary sedimentation tank 11. Further, the control unit 60 may receive a signal from a sensor (not shown) provided in the final sedimentation tank 13 and monitor the concentration of the organic chromaticity component contained in the water to be treated stored in the final sedimentation tank 13. Further, the control unit 60 may receive a signal from a sensor (not shown) provided in the reaction tank 12 and monitor the concentration of the organic chromaticity component contained in the water to be treated being processed in the reaction tank 12. As a sensor capable of detecting the concentration of the organic chromaticity component in these waters to be treated, for example, an absorptiometer that measures the absorbance of the water to be treated at a predetermined wavelength can be used.

[0027] Based on the concentration of the organic chromaticity component in the water to be treated in at least any one of the primary sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13, the control unit 60 may adjust the amount of the water to be treated returned from the final sedimentation tank 13 to the reaction tank 12 by controlling the pump 21 or the like.

[0028] Specifically, when the concentration of the organic chromaticity component in the water to be treated is higher than a predetermined value, the control unit 60 may increase the amount of the water to be treated returned from the final sedimentation tank 13 to the reaction tank 12. Further, when the concentration of the organic chromaticity component in the water to be treated is lower than a predetermined value, the control unit 60 may decrease the amount of the water to be treated returned from the final sedimentation tank 13 to the reaction tank 12.

[0029] (Example of wastewater treatment by the wastewater treatment apparatus) Subsequently, with reference to FIG. 1, an example of wastewater treatment by the wastewater treatment apparatus 100 of Embodiment 1 will be described. As described above, in the wastewater treatment apparatus 100 of Embodiment 1, Bacillus proteolyticus is used for wastewater treatment.

[0030] When starting up the wastewater treatment apparatus 100, for example, an inoculum of Bacillus proteolyticus is introduced into the reaction tank 12. Then, water containing an organic chromaticity component is flowed into the reaction tank 12 into which the inoculum of Bacillus proteolyticus has been introduced to acclimatize the inoculum.

[0031] When the wastewater treatment apparatus 100 is in operation, the wastewater to be treated is treated by Bacillus proteolyticus that has been acclimated to organic color components. According to the newly discovered knowledge of the present inventors, Bacillus proteolyticus produces an enzyme having a decomposition ability for organic color components. Specifically, this enzyme has a function of cleaving an azo bond possessed by an azo dye or the like, which is an organic color component. Due to the function of this enzyme produced by Bacillus proteolyticus, the organic color components contained in the wastewater to be treated are decomposed, and the wastewater to be treated is treated.

[0032] In addition, Bacillus proteolyticus is known to produce protease separately from the above enzyme. Protease is an enzyme that cleaves the peptide bond (-C(=O)-NH-) of a protein. Therefore, in the reaction tank 12 into which Bacillus proteolyticus is introduced, it is also possible to decompose organic substances such as proteins that may be contained in the wastewater to be treated.

[0033] (Summary) As described above, Bacillus proteolyticus is known as a microorganism that produces protease. The protease produced by Bacillus proteolyticus cleaves the peptide bond of a protein.

[0034] The present inventors have found that Bacillus proteolyticus produces an enzyme different from protease. And that enzyme had a function of cleaving an azo bond. As a result of intensive research, the present inventors have successfully applied Bacillus proteolyticus to the treatment of colored wastewater, which is a serious problem in developing countries, by utilizing the dye-decomposing ability of the above enzyme.

[0035] According to the wastewater treatment apparatus 100 of Embodiment 1, a reaction tank 12 is provided that treats wastewater containing organic color components with an enzyme produced by Bacillus proteolyticus. By thus causing Bacillus proteolyticus to exist in the biological treatment system, it becomes possible to treat colored wastewater at low cost as compared with, for example, physicochemical treatment. Thereby, it is possible to contribute to solving the problems of wastewater treatment in developing countries, for example.

[0036] According to the wastewater treatment apparatus 100 of Embodiment 1, since Bacillus proteolyticus also produces protease, it is also possible to decompose organic substances other than the organic chromaticity component. As a result, it is not necessary to separately provide a reaction tank or apparatus, and no new operations such as separate reactions are required, so that the cost can be further reduced.

[0037] (Modification 1) Next, with reference to FIG. 2, the wastewater treatment apparatus 101 of Modification 1 of Embodiment 1 will be described. The wastewater treatment apparatus 101 of Modification 1 is different from the wastewater treatment apparatus 100 of Embodiment 1 described above in that it includes a culture tank 14.

[0038] FIG. 2 is a diagram showing an example of the configuration of the wastewater treatment apparatus 101 according to Modification 1 of Embodiment 1. In FIG. 2, the same components as those in the configuration of Embodiment 1 described above are denoted by the same reference numerals, and the description thereof is omitted.

[0039] As shown in FIG. 2, the wastewater treatment apparatus 101 of Modification 1 includes, in addition to each component of Embodiment 1 described above, a culture tank 14, an input pipe 44, and a valve 54. Further, the wastewater treatment apparatus 101 includes a control unit 61 instead of the control unit 60 of Embodiment 1 described above.

[0040] The culture tank 14 is disposed, for example, above the reaction tank 12. The culture tank 14 is configured such that an inoculum of Bacillus proteolyticus is introduced therein and Bacillus proteolyticus can be grown in the culture tank 14.

[0041] Specifically, a liquid medium for growing Bacillus proteolyticus is introduced into the culture tank 14. Further, the culture tank 14 includes, for example, a heater (not shown) for heating the liquid medium to a predetermined temperature. As the liquid medium, for example, a mixed solution containing components such as nutrient broth, glucose, sodium chloride, and soluble starch can be used.

[0042] To these mixed solutions, an azo dye such as Acid Red 88 may be further added. By containing the azo dye in the liquid medium, it is possible to suppress the growth of microorganisms other than Bacillus proteolyticus in the culture tank 14. In addition, by containing the azo dye in the liquid medium, it is also possible to expect the effect of acclimating Bacillus proteolyticus to the azo dye.

[0043] By holding the above liquid medium at a temperature suitable for the growth of Bacillus proteolyticus around 30°C for several days, for example, Bacillus proteolyticus can be grown in the culture tank 14.

[0044] One end of the input pipe 44 is connected to the lower end of the culture tank 14. The other end of the input pipe 44 is connected to the reaction tank 12. Thereby, the culture tank 14 is connected to the reaction tank 12 of the wastewater treatment apparatus 101. The culture tank 14 is preferably connected to the upstream side of the reaction tank 12, such as the section 12a on the most upstream side of the reaction tank 12. A valve 54 is provided in the input pipe 44. By opening and closing the valve 54, the inflow of the culture solution containing Bacillus proteolyticus from the culture tank 14 into the reaction tank 12 is started and stopped.

[0045] In the configuration of Modification 1, the reaction tank 12, the culture tank 14, the input pipe 44, and the valve 54 are included in the treatment mechanism for treating wastewater with Bacillus proteolyticus. The above-described aeration equipment (the blower 31, the air supply pipe 41, the valve 51, and the air diffuser plate 32) and the return equipment (the return pipe 42 and the pump 21) may be included in the treatment mechanism.

[0046] The control unit 61 is configured as a computer including, for example, a CPU, a ROM, and a RAM, similar to the control unit 60 of the above-described Embodiment 1, and controls each part of the wastewater treatment apparatus 101 including temperature control and heat preservation of the culture tank 14 and opening / closing control of the valve 54.

[0047] The control unit 61 controls the temperature of the culture tank 14 to an appropriate temperature and maintains it for a predetermined time, thereby growing Bacillus proteolyticus in the culture tank 14. Further, the control unit 61 controls at least one of the input timing and the input amount of the culture solution containing Bacillus proteolyticus from the culture tank 14 to the reaction tank 12 by controlling the opening and closing of the valve 54 of the input pipe 44.

[0048] As described above, the control unit 61 may monitor the concentration of the organic chromaticity component of the water to be treated in at least one of the first sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13. The control unit 61 may control at least one of the input timing and the input amount of the culture solution containing Bacillus proteolyticus from the culture tank 14 to the reaction tank 12 according to the concentration of the organic chromaticity component of the water to be treated.

[0049] Specifically, when the concentration of the organic chromaticity component of the water to be treated is higher than a predetermined value, the control unit 60 may increase the input frequency or increase the input amount of the culture solution containing Bacillus proteolyticus from the culture tank 14 to the reaction tank 12. Further, when the concentration of the organic chromaticity component of the water to be treated is lower than a predetermined value, the control unit 60 may decrease the input frequency or decrease the input amount of the culture solution containing Bacillus proteolyticus from the culture tank 14 to the reaction tank 12.

[0050] According to the wastewater treatment apparatus 101 of Modification 1, the same effects as those of the wastewater treatment apparatus 100 of Embodiment 1 described above are achieved.

[0051] According to the wastewater treatment apparatus 101 of Modification 1, a culture tank 14 connected to the reaction tank 12 is provided. Thereby, Bacillus proteolyticus can be stably supplied to the reaction tank 12, and dye decomposition can be stably performed.

[0052] According to the wastewater treatment apparatus 101 of Modification 1, the control unit 61 controls at least one of the timing and amount of Bacillus proteolyticus input from the culture tank 14 to the reaction tank 12. Thereby, the operation through manual labor can be omitted, labor costs can be reduced, and human error can be suppressed.

[0053] (Modification 2) Next, the wastewater treatment apparatus of Modification 2 of Embodiment 1 will be described. The wastewater treatment apparatus of Modification 2 is different from the wastewater treatment apparatus 101 of Modification 1 described above in that it includes a culture solution tank instead of the culture tank 14.

[0054] The culture solution tank of Modification 2 is connected to, for example, the upstream side of the reaction tank 12 by facilities similar to the input pipe 44 and valve 54 of Modification 1 described above. The culture solution tank can store the culture solution in which Bacillus proteolyticus has been cultured. The culture solution is a supernatant liquid or the like from which Bacillus proteolyticus has been separated by centrifugation or the like from the culture solution after culturing Bacillus proteolyticus. Therefore, substantially, the supernatant liquid does not contain Bacillus proteolyticus. However, the supernatant liquid contains a predetermined amount of enzymes having the ability to decompose pigments produced by Bacillus proteolyticus during the growth process. In order to increase the concentration of the enzyme, a concentrated solution obtained by concentrating the supernatant liquid may be stored in the culture solution tank.

[0055] In the configuration of Modification 2, the reaction tank 12, the culture solution tank, and facilities such as the input pipe and valve connected to the culture solution tank are included in the treatment mechanism for treating wastewater with Bacillus proteolyticus. The above-described aeration facilities (blower 31, air supply pipe 41, valve 51, and air diffuser plate 32) and return facilities (return pipe 42 and pump 21) may be included in the treatment mechanism.

[0056] The control unit of Modification 2 is configured as a computer including, for example, a CPU, a ROM, and a RAM, etc., similar to the control unit 60 of the above-described Embodiment 1, and controls each component of the wastewater treatment apparatus of Modification 2, including at least control of either the supply timing or the supply amount of the culture solution from the culture solution tank to the reaction tank 12, more specifically, the supernatant of the culture solution or the concentrated solution of the supernatant.

[0057] As described above, the control unit of Modification 2 may monitor the concentration of the organic chromaticity component of the water to be treated in at least any one of the primary sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13. The control unit of Modification 2 may control at least either the supply timing or the supply amount of the supernatant or the concentrated solution from the culture solution tank to the reaction tank 12 according to the concentration of the organic chromaticity component of the water to be treated.

[0058] Specifically, when the concentration of the organic chromaticity component of the water to be treated is higher than a predetermined value, the control unit of Modification 2 may increase the supply frequency or increase the supply amount of the supernatant or the concentrated solution from the culture solution tank to the reaction tank 12. Also, when the concentration of the organic chromaticity component of the water to be treated is lower than a predetermined value, the control unit of Modification 2 may decrease the supply frequency or decrease the supply amount of the supernatant or the concentrated solution from the culture solution tank to the reaction tank 12.

[0059] According to the wastewater treatment apparatus of Modification 2, the same effects as those of the wastewater treatment apparatus 100 of the above-described Embodiment 1 are achieved.

[0060] According to the wastewater treatment apparatus of Modification 2, a culture solution tank connected to the reaction tank 12 is provided. Thereby, since the enzyme component having the ability to decompose dyes can be directly supplied to the reaction tank 12, the concentration of the enzyme in the reaction tank 12, etc. can be controlled more precisely. Also, it is possible to suppress the consumption of Bacillus proteolyticus itself in the reaction tank 12, and it is possible to cause further enzyme production in the Bacillus proteolyticus separated from the culture solution.

[0061] (Modification 3) Next, a wastewater treatment apparatus according to Modification 3 of Embodiment 1 will be described. The wastewater treatment apparatus of Modification 3 is different from the wastewater treatment apparatus 101 of Modification 1 described above in that it includes a microbial agent container instead of the culture tank 14.

[0062] The microbial agent container of Modification 3 is connected, for example, to the upstream side of the reaction tank 12 by facilities similar to the input pipe 44 and valve 54 of Modification 1 described above. The microbial agent container can accommodate a microbial agent containing Bacillus proteolyticus. The microbial agent can take various forms such as powder, liquid, or tablet.

[0063] In the configuration of Modification 3, the reaction tank 12, the microbial agent container, and facilities such as the input pipe and valve connected to the microbial agent container are included in the treatment mechanism for treating wastewater with Bacillus proteolyticus. The above-described aeration facilities (blower 31, air supply pipe 41, valve 51, and diffuser plate 32) and return facilities (return pipe 42 and pump 21) may also be included in the treatment mechanism.

[0064] The control unit of Modification 3 is configured as a computer including, for example, a CPU, ROM, and RAM, similar to the control unit 60 of Embodiment 1 described above, and controls each component of the wastewater treatment apparatus of Modification 3, including at least the control of the supply timing and supply amount of the microbial agent from the microbial agent container to the reaction tank 12.

[0065] As described above, the control unit of Modification 3 may monitor the concentration of the organic chromaticity component of the water to be treated in at least any one of the primary sedimentation tank 11, the reaction tank 12, and the final sedimentation tank 13. The control unit of Modification 3 may control at least any one of the supply timing and supply amount of the microbial agent from the microbial agent container to the reaction tank 12 according to the concentration of the organic chromaticity component of the water to be treated.

[0066] Specifically, when the concentration of the organic chromaticity component in the water to be treated is higher than a predetermined value, the control unit of Modification 3 may increase the supply frequency of the microbial preparation from the microbial preparation container to the reaction tank 12 or increase the supply amount. Further, when the concentration of the organic chromaticity component in the water to be treated is lower than a predetermined value, the control unit of Modification 3 may decrease the supply frequency of the microbial preparation from the microbial preparation container to the reaction tank 12 or decrease the supply amount.

[0067] According to the wastewater treatment apparatus of Modification 3, the same effects as those of the wastewater treatment apparatus 100 of the above-described Embodiment 1 are achieved.

[0068] According to the wastewater treatment apparatus of Modification 3, a microbial preparation container connected to the reaction tank 12 is provided. Thereby, since the microbial preparation containing Bacillus proteolyticus can be supplied to the reaction tank 12, the concentration of the enzyme in the reaction tank 12 and the like can be controlled more precisely. Further, by using Bacillus proteolyticus in the form of a microbial preparation, handling becomes easy. In addition, it is also easy to use in combination with a microbial preparation containing a useful microorganism different from Bacillus proteolyticus, and the wastewater treatment ability can be further enhanced.

[0069] [Embodiment 2] Next, Embodiment 2 will be described with reference to the drawings. The wastewater treatment apparatus of Embodiment 2 is different from the wastewater treatment apparatus 100 of the above-described Embodiment 1 in that an immobilization carrier is disposed on the upstream side of the reaction tank.

[0070] (Configuration Example of Wastewater Treatment Apparatus) FIG. 3 is a diagram showing an example of the configuration of a wastewater treatment apparatus 200 according to Embodiment 2. In FIG. 3, the same components as those in the configuration of the above-described Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0071] As shown in FIG. 3, the wastewater treatment apparatus 200 of Embodiment 2 includes, in order from the upstream side, a primary sedimentation tank 11, a carrier immersion tank 71, a reaction tank 92, and a final sedimentation tank 13. The primary sedimentation tank 11, the carrier immersion tank 71, the reaction tank 92, and the final sedimentation tank 13 may be arranged with a gradient such that their arrangement positions become lower in this order.

[0072] The carrier immersion tank 71 is arranged in the flow path of the water to be treated flowing from the primary sedimentation tank 11 to the reaction tank 92, and is configured such that, for example, an immobilized carrier 81 on which Bacillus proteolyticus is immobilized can be immersed in the water to be treated in the carrier immersion tank 71. Further, the carrier immersion tank 71 may be provided with a heater (not shown) or the like that heats the inside of the carrier immersion tank 71 to a temperature of around 30°C, which is suitable for the activity of Bacillus proteolyticus, for example.

[0073] The immobilized carrier 81 is configured such that, for example, Bacillus proteolyticus can be preferentially attached and immobilized. That is, in the immobilized carrier 81, it is preferable that Bacillus proteolyticus is the dominant species.

[0074] Specifically, the immobilized carrier 81 is composed of a material having a large specific surface area, such as a porous material, for example, or has a material having a large specific surface area on its outermost surface. The specific surface area may be increased by the immobilized carrier 81 having a shape such as a corrugated plate shape, a net shape, a string shape, a spherical shape, a cylindrical shape, a honeycomb shape, or the like, for example.

[0075] Since the immobilized carrier 81 has a large specific surface area, more Bacillus proteolyticus can be attached to and immobilized on the immobilized carrier 81. In addition, the contact efficiency between the immobilized carrier 81 and the water to be treated can be increased.

[0076] Further, the immobilized carrier 81 having the above-described shape may be a fluidized bed carrier configured to be able to flow in the water to be treated in the carrier immersion tank 71. By the immobilized carrier 81 flowing in the water to be treated, the contact efficiency between the immobilized carrier 81 and the water to be treated can be further increased.

[0077] In the carrier immersion tank 71, the enzyme produced by Bacillus proteolyticus elutes into the water to be treated that has come into contact with the immobilized carrier 81. The water to be treated is sent to the subsequent reaction tank 92 in a state containing the enzyme having this dye-decomposing ability.

[0078] The reaction tank 92 is a water tank equipped with a mechanism for reacting the organic chromaticity component in the water to be treated with the enzyme to decompose and remove the organic chromaticity component. In the example of FIG. 3, a reaction tank 92 having only one compartment and only one air diffuser plate 32 of the aeration facility is shown. However, similar to the reaction tank 12 of the above-described Embodiment 1, the reaction tank 92 may have a plurality of compartments each provided with an air diffuser plate 32.

[0079] In addition, in the configuration of Embodiment 2, the carrier immersion tank 71 and the reaction tank 92 are included in the treatment mechanism for treating wastewater with Bacillus proteolyticus. The immobilized carrier 81 immersed in the carrier immersion tank 71 may be included in the treatment mechanism. Further, the aeration facility (blower 31, air supply pipe 41, valve 51, and air diffuser plate 32), and the return facility (return pipe 42 and pump 21) may be included in the treatment mechanism.

[0080] Although not shown in FIG. 3, equipment for removing excess sludge deposited at the bottom of the final sedimentation tank 13 may be connected to the return pipe 42 of the return facility, similar to the sludge discharge pipe 43 and pump 22 of the above-described Embodiment 1.

[0081] The wastewater treatment apparatus 200 of Embodiment 2 also includes a control unit 62. Similar to the control unit 60 of the above-described Embodiment 1, the control unit 62 is configured as a computer including, for example, a CPU, ROM, and RAM, and controls each part of the wastewater treatment apparatus 200, including control of temperature adjustment and heat retention of the carrier immersion tank 71.

[0082] According to the wastewater treatment apparatus 200 of Embodiment 2, the same effects as those of the wastewater treatment apparatus 100 of the above-described Embodiment 1 are achieved.

[0083] According to the wastewater treatment apparatus 200 of Embodiment 2, a carrier immersion tank 71 disposed upstream of the reaction tank 92 is provided. Thereby, the immobilized carrier 81 on which Bacillus proteolyticus is immobilized can be used for treating the water to be treated. By using the immobilized carrier 81, Bacillus proteolyticus can be maintained in the biological treatment system. Further, by appropriately replenishing the immobilized carrier 81 to the carrier immersion tank 71, secular changes such as a decrease in treatment performance can be suppressed.

[0084] (Modification example) Next, with reference to FIG. 4, the wastewater treatment apparatus 201 of the modification example of Embodiment 2 will be described. In the wastewater treatment apparatus 201 of the modification example, the point that the rotating disk 82 is used as the immobilized carrier is different from the wastewater treatment apparatus 200 of Embodiment 2 described above.

[0085] FIG. 4 is a diagram showing an example of the configuration of the wastewater treatment apparatus 201 according to the modification example of Embodiment 2. In FIG. 4, the same components as those in the configuration of Embodiment 2 described above are denoted by the same reference numerals, and the description thereof is omitted.

[0086] As shown in FIG. 4, the wastewater treatment apparatus 201 of the modification example includes a carrier immersion tank 72 capable of immersing the rotating disk 82 instead of the carrier immersion tank 71 of Embodiment 2 described above. The carrier immersion tank 72 may be provided with a heater (not shown) for heating the inside of the carrier immersion tank 72 to a temperature around 30° C., which is suitable for the activity of Bacillus proteolyticus, for example.

[0087] The rotating disk 82 is a carrier configured as a disk-shaped rotating body with an immobilized carrier that preferentially attaches and immobilizes Bacillus proteolyticus. In order to immobilize Bacillus proteolyticus, for example, fibrous contact bodies are arranged on the surface of the rotating disk 82.

[0088] With at least a part of the rotating disk 82 immersed in the carrier immersion tank 72, the entire surface of the rotating disk 82 can be brought into contact with the water to be treated in the carrier immersion tank 72 by rotating the rotating disk 82 by power from a motor (not shown).

[0089] In the carrier immersion tank 72, enzymes produced by Bacillus proteolyticus elute into the water to be treated that has come into contact with the rotating disk 82. The water to be treated is sent to the subsequent reaction tank 92 in a state containing the enzyme having this dye-decomposing ability.

[0090] In addition, in the configuration of the modification example, the carrier immersion tank 72 and the reaction tank 92 are included in a treatment mechanism for treating wastewater with Bacillus proteolyticus. The rotating disk 82 immersed in the carrier immersion tank 72 may be included in the treatment mechanism. Further, the aeration equipment (the blower 31, the air supply pipe 41, the valve 51, and the air diffuser plate 32), and the return equipment (the return pipe 42 and the pump 21) may be included in the treatment mechanism.

[0091] The wastewater treatment apparatus 201 of the modification example also includes a control unit 63. The control unit 63 is configured as a computer including, for example, a CPU, a ROM, and a RAM, similar to the control unit 60 of the above-described Embodiment 1, and controls each part of the wastewater treatment apparatus 201, including, for example, temperature adjustment and heat retention of the carrier immersion tank 72, and rotation control of the rotating disk 82.

[0092] According to the wastewater treatment apparatus 201 of the modification example, the same effects as those of the wastewater treatment apparatus 200 of the above-described Embodiment 2 are achieved.

[0093] According to the wastewater treatment apparatus 201 of the modification example, the rotating disk 82 in which Bacillus proteolyticus is preferentially immobilized is arranged on the upstream side of the reaction tank 92. In this way, by immobilizing and preferentially optimizing Bacillus proteolyticus on the rotating disk 82, the dye component can be decomposed more efficiently. Also, space saving can be achieved.

[0094] In addition, in the above-described Embodiment 2 and the modification example, the carrier immersion tanks 71 and 72 capable of immersing the immobilization carrier 81 or the rotating disk 82 are provided. However, in a device configuration such as the wastewater treatment apparatus 100 of the above-described Embodiment 1, for example, the immobilization carrier 81 or the rotating disk 82 may be directly immersed in the reaction tank 12.

Example

[0095] Next, examples will be described with reference to the drawings. In the examples, the resolution of the organic chromaticity component of the enzyme produced by Bacillus proteolyticus was evaluated.

[0096] (Cultivation of Bacillus proteolyticus) Bacillus proteolyticus was inoculated into a liquid medium containing the components listed in Table 1 and cultured at 30°C for 72 hours to grow Bacillus proteolyticus.

[0097]

Table 1

[0098] By including the azo dye Acid Red 88 in the liquid medium, the growth of other microorganisms other than Bacillus proteolyticus can be suppressed.

[0099] (Test for decomposition and removal of organic chromaticity component) Using the Bacillus proteolyticus cultured as described above, a test for decomposition and removal of the organic chromaticity component was conducted. Acid Red 88 was used as an example of a hardly decomposable organic chromaticity component. That is, the culture solution containing the cultured Bacillus proteolyticus was added to a liquid medium containing Acid Red 88, and the removal performance of Acid Red 88 by Bacillus proteolyticus was evaluated while shaking and culturing at a temperature of about 30°C.

[0100] The removal performance of Acid Red 88 was evaluated by measuring the chromaticity. For the chromaticity measurement, a method of measuring the absorbance of the liquid medium containing Acid Red 88 with respect to light with a wavelength of 504 nm was used. The higher the absorbance with respect to light with a wavelength of 504 nm, the stronger the red color of the liquid medium, that is, the higher the content of Acid Red 88.

[0101] In addition, the removal rate of Acid Red 88, which is an organic chromaticity component, was determined from the measured absorbance. More specifically, the absorbances of standard samples with known dye concentrations prepared in advance were measured at multiple concentrations to obtain a calibration curve equation. The absorbance of the liquid medium containing Bacillus proteolyticus measured as described above was substituted into this calibration curve equation to calculate the dye concentration of the liquid medium. The removal rate of Acid Red 88 was calculated based on the dye concentration EV obtained by calculating the liquid medium after a predetermined time has elapsed, with reference to the dye concentration IV obtained by calculating the liquid medium immediately after adding the culture solution containing Bacillus proteolyticus. The calculation formula for obtaining the removal rate from the dye concentrations IV and EV is shown below.

[0102] Removal rate (%) = 100×(IV - EV) / IV

[0103] If the decomposition of Acid Red 88 in the liquid medium proceeds over time, the absorbance and dye concentration also decrease due to the decrease in the content of Acid Red 88. Therefore, if the removal rate increases over time, it indicates that the decomposition of Acid Red 88 is progressing.

[0104] (Time-dependent change in absorbance) Figure 5 is a graph showing the time-dependent change in the absorbance of the Acid Red 88-containing liquid medium to which the Bacillus proteolyticus-containing culture solution according to the example was added. The horizontal axis of the graph in Figure 5 is the elapsed time (hr), and the vertical axis is the absorbance (Abs) with respect to the light of wavelength 504 nm in the liquid medium containing Acid Red 88.

[0105] As shown in Figure 5, immediately after adding the culture solution containing Bacillus proteolyticus, that is, when the elapsed time was 0 hours, the absorbance of the liquid medium was slightly more than 0.2. In contrast, 17 hours after the addition of the culture solution containing Bacillus proteolyticus, the absorbance of the liquid medium had decreased to about 0.05. From this, it can be seen that Acid Red 88 in the liquid medium was decomposed by the culture solution containing Bacillus proteolyticus.

[0106] (Time-dependent change in removal rate) Figure 6 is a graph showing the change over time in the removal rate of Acid Red 88 contained in a liquid medium to which a Bacillus proteolyticus-containing culture solution according to an example was added. The horizontal axis of the graph in Figure 6 represents the passage of time (hr), and the vertical axis represents the reduction rate (%) of Acid Red 88 contained in the liquid medium.

[0107] As shown in Figure 6, 17 hours after adding the culture solution containing Bacillus proteolyticus, the removal rate of Acid Red 88 contained in the liquid medium was 93%. That is, it can be seen that 93% of the Acid Red 88 originally contained in the liquid medium was removed after 17 hours.

[0108] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0109] 12, 92 Reaction tank 14 Culture tank 60, 61, 62, 63 Control unit 71, 72 Carrier immersion tank 81 Immobilized carrier 82 Rotating disk 100, 101, 200, 201 Wastewater treatment device

Claims

1. A wastewater treatment apparatus for treating wastewater containing an organic chromaticity component, comprising a treatment mechanism for treating the wastewater with an enzyme produced by Bacillus proteolyticus, wherein the organic chromaticity component is an azo dye, and the enzyme decomposes at least a part of the azo bond of the azo dye. Wastewater treatment apparatus.

2. The enzyme reduces the chromaticity of the wastewater, The wastewater treatment apparatus according to claim 1.

3. The treatment mechanism has a reaction tank for reacting the enzyme with the organic chromaticity component in the wastewater. The wastewater treatment apparatus according to claim 1 or claim 2.

4. The reaction tank is configured to be able to bring the wastewater into contact with at least any one of the Bacillus proteolyticus, an immobilization carrier on which the Bacillus proteolyticus is immobilized, and a rotating disk configured to rotatably support the immobilization carrier. The wastewater treatment apparatus according to claim 3.

5. The treatment mechanism further has a culture tank connected to the reaction tank, and the culture tank is configured to be able to grow the Bacillus proteolyticus and supply a culture solution containing the grown Bacillus proteolyticus to the reaction tank. The wastewater treatment apparatus according to claim 3.

6. The wastewater treatment apparatus according to claim 5, further comprising a control unit for controlling at least any one of the supply timing and the supply amount of the culture solution containing the Bacillus proteolyticus from the culture tank to the reaction tank. The wastewater treatment apparatus according to claim 5.

7. The treatment mechanism further includes a culture solution tank connected to the reaction tank, The culture solution tank, is configured to store the supernatant after separating the Bacillus proteolyticus from the culture solution for culturing the Bacillus proteolyticus, or a concentrated solution obtained by concentrating the supernatant, and supply the stored supernatant or the concentrated solution to the reaction tank, The wastewater treatment apparatus according to claim 3.

8. The wastewater treatment apparatus further includes a control unit that controls at least one of the supply timing and the supply amount of the supernatant or the concentrated solution from the culture solution tank to the reaction tank, The wastewater treatment apparatus according to claim 7.

9. The treatment mechanism further includes a microbial agent container connected to the reaction tank, The microbial agent container, is configured to contain a microbial agent containing the Bacillus proteolyticus and supply the microbial agent to the reaction tank, The wastewater treatment apparatus according to claim 3.

10. The form of the microbial agent is powdery, liquid, or tablet-shaped, The wastewater treatment apparatus according to claim 9.

11. The wastewater treatment apparatus further includes a control unit that controls at least one of the supply timing and the supply amount of the microbial agent from the microbial agent container to the reaction tank, The wastewater treatment apparatus according to claim 10.

12. The control unit, controls at least one of the supply timing and the supply amount according to the concentration of the organic chromaticity component in the wastewater, The wastewater treatment apparatus according to claim 6, claim 8, or claim 11.

13. The treatment mechanism, includes a reaction tank for reacting the enzyme with the organic chromaticity component in the wastewater, It has a carrier immersion tank arranged on the upstream side of the reaction tank, The carrier immersion tank, is configured to be able to immerse an immobilized carrier obtained by immobilizing Bacillus proteolyticus, The wastewater treatment apparatus according to claim 1 or claim 2.

14. The immobilized carrier is a fluidized bed carrier, The fluidized bed carrier, flows in the carrier immersion tank by the wastewater flowing into the carrier immersion tank, The wastewater treatment apparatus according to claim 13.

15. The immobilized carrier, is a rotating disk capable of rotating while bringing the wastewater into contact therewith, The wastewater treatment apparatus according to claim 13.

16. A wastewater treatment method for treating wastewater containing an organic color component, comprising: treating the wastewater with an enzyme produced by Bacillus proteolyticus, the organic color component is an azo dye, the enzyme decomposes at least a part of the azo bond of the azo dye, Wastewater treatment method.

17. The enzyme reduces the chromaticity of the wastewater, The wastewater treatment method according to claim 16.

18. bringing the wastewater into contact with at least any one of a culture solution containing Bacillus proteolyticus, a supernatant after separating Bacillus proteolyticus from the culture solution, a concentrated solution obtained by concentrating the supernatant, a microbial preparation containing Bacillus proteolyticus, an immobilized carrier obtained by immobilizing Bacillus proteolyticus, and a rotating disk configured to be rotatable with the immobilized carrier, The wastewater treatment method according to claim 16 or claim 17.

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