Organic matter decomposition system

Abstract

To provide an organic matter decomposition system which decomposes an organic matter by anaerobic biological treatment without performing aerobic biological treatment.SOLUTION: According to an embodiment, an organic matter decomposition system includes: a hardness removing unit that removes hardness components from raw water to be treated; a carbon dioxide removing unit that removes carbon dioxide components from the raw water from which the hardness components have been removed; an alkali injection unit that injects alkali into the raw water from which the carbon dioxide components have been removed; an insoluble organic matter concentration unit that concentrates an insoluble organic matter contained in the raw water to which the alkali has been injected; and an anaerobic biological treatment unit that performs anaerobic biological treatment to the raw water in which the insoluble organic matter has been concentrated, to decompose the insoluble organic matter.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an organic matter decomposition system that decomposes organic matter contained in raw water by anaerobic biological treatment. [Background technology]

[0002] 2. Description of the Related Art Conventionally, when raw water such as industrial wastewater or sewage contains organic matter, the organic matter has generally been decomposed by biological treatment.

[0003] There are two types of biological treatment: aerobic biological treatment and anaerobic biological treatment. Aerobic biological treatment decomposes organic matter by supplying oxygen to aerobic microorganisms through aeration. However, the amount of electricity required for aeration is very large. On the other hand, anaerobic biological treatment does not use aeration, so electricity consumption is significantly reduced. In addition, the biogas generated can be used as energy. However, anaerobic biological treatment can only be applied to raw water that contains a high concentration of organic matter.

[0004] For this reason, many techniques have been devised to concentrate the organic matter in raw water.

[0005] Organic matter in raw water is divided into insoluble organic matter and soluble organic matter. Insoluble organic matter can be concentrated using a settling tank, a microfiltration membrane (hereinafter also referred to as "MF membrane"), or an ultrafiltration membrane (hereinafter also referred to as "UF membrane"). However, when using an MF membrane or UF membrane, the separation performance of the membrane decreases due to biofouling. In addition, a settling tank can only collect solid organic matter with large particle sizes, and cannot collect organic matter with small particle sizes even if it is in solid form.

[0006] On the other hand, soluble organic matter can be concentrated using a forward osmosis membrane (hereinafter also referred to as an "FO membrane") or a reverse osmosis membrane (hereinafter also referred to as an "RO membrane"). When using an FO membrane, a draw solution is required. This requires the treatment and regeneration of the draw solution. In addition, when concentrating using an RO membrane, not only organic matter but also inorganic ions are concentrated, which causes hardness scaling and silica scaling. In addition, biofouling is likely to occur on the RO membrane. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 61-234989 [Patent Document 2] Special Publication No. 2000-511109 [Patent Document 3] JP 2014-8431 A Summary of the Invention [Problem to be solved by the invention]

[0008] Thus, due to the problems of scaling and biofouling, there is no organic matter decomposition system that decomposes organic matter using only anaerobic biological treatment without also performing aerobic biological treatment.

[0009] If such an organic matter decomposition system could be realized, it would not only be possible to decompose organic matter with little electricity consumption, but it would also be possible to recover bioenergy obtained from the decomposition of the organic matter.

[0010] An object of the present invention is to provide an organic matter decomposition system that decomposes organic matter by anaerobic biological treatment without performing aerobic biological treatment. [Means for solving the problem]

[0011] The organic matter decomposition system of the embodiment includes a hardness removal unit that removes hardness components from the raw water to be treated, a carbonate removal unit that removes carbonate components from the raw water from which the hardness components have been removed, an alkali injection unit that injects alkali into the raw water from which the carbonate components have been removed, an insoluble organic matter concentration unit that concentrates insoluble organic matter contained in the raw water to which the alkali has been injected, and an anaerobic biological treatment unit that performs anaerobic biological treatment on the raw water in which the insoluble organic matter has been concentrated, and decomposes the insoluble organic matter. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an organic matter decomposition system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a configuration example of an organic matter decomposition system according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing a configuration example of an organic matter decomposition system according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as the actual ones. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with respect to the previous drawings are given the same reference numerals, and detailed explanations and duplicated explanations are omitted as appropriate.

[0014] (First embodiment) An organic matter decomposition system according to a first embodiment of the present invention will be described.

[0015] FIG. 1 is a block diagram showing an example of the configuration of an organic matter decomposition system according to a first embodiment of the present invention.

[0016] That is, the organic matter decomposition system 10A of the first embodiment includes a raw water supply tank 12, a solid matter separation section 14, a hardness removal section 16, a carbon dioxide removal section 18, an alkali injection section 20, an insoluble organic matter concentration section 22, an anaerobic biological treatment section 24, and a post-treatment section 26.

[0017] The raw water supply tank 12 stores raw water a such as industrial wastewater or sewage. The raw water a usually contains organic matter, hardness components (calcium, magnesium, carbonate ions), scaling substances such as silica, fouling substances, etc. The concentration range of the raw water a can be, for example, either or both of a BOD (Biochemical Oxygen Demand) of 2000 mg / l or less and a COD (Chemical Oxygen Demand) of 2000 mg / l or less. The raw water a stored in the raw water supply tank 12 is supplied from the raw water supply tank 12 to the solid separation section 14.

[0018] In addition, although it has been stated that the concentration range of raw water a can be either or both of a BOD of 2000 mg / l or less and a COD (Chemical Oxygen Demand) of 2000 mg / l or less, this condition may also be applied to raw water b from which solids have been separated in the solid separation section 14 described below.

[0019] The solid separation section 14 separates solids from the raw water a supplied from the raw water supply tank 12, for example, by coagulation sedimentation, sand filtration, etc. The raw water b from which the solids have been separated is supplied from the solid separation section 14 to the hardness removal section 16.

[0020] The hardness removal section 16 removes hardness components from the raw water b supplied from the solid separation section 14, for example, by using an ion exchange resin. This makes it possible to remove scaling substances. The raw water c from which the hardness components have been separated is supplied from the hardness removal section 16 to the carbon dioxide removal section 18.

[0021] The carbonate removal section 18 removes carbonate components from the raw water c supplied from the hardness removal section 16, for example, by a decarbonation tower. The raw water d from which the carbonate components have been removed is supplied from the carbonate removal section 18 to the insoluble organic matter concentration section 22.

[0022] The alkali injecting section 20 is connected to the middle of the supply line from the carbon dioxide removing section 18 to the insoluble organic matter concentrating section 22, and injects an alkali e into the raw water d. The alkali e is not limited to, but may be, for example, caustic soda. By injecting the alkali e, the raw water d becomes raw water f with a high pH of 9 to 11, and is supplied to the insoluble organic matter concentrating section 22. The raw water f with a high pH in this manner can avoid biofouling in membranes such as MF membranes and UF membranes applied to the insoluble organic matter concentrating section 22.

[0023] The insoluble organic matter concentrating section 22 concentrates the insoluble organic matter contained in the raw water f, and can be, for example, a filtration membrane having a pore size of about 0.01 μm to 10 μm. Although not limited to, such a filtration membrane is preferably an MF membrane (pore size of 0.1 to 10 μm) or a UF membrane (pore size of about 0.01 μm). Depending on the particle size of the insoluble organic matter contained in the raw water f, the insoluble organic matter concentrating section 22 can be realized by only an MF membrane, by only a UF membrane, or by a configuration including both an MF membrane and a UF membrane, such as by arranging an MF membrane and a UF membrane in series.

[0024] Concentrated water g, which is raw water in which insoluble organic matter has been concentrated by the insoluble organic matter concentrating section 22, is supplied to the anaerobic biological treatment section 24. In the insoluble organic matter concentrating section 22, raw water j in which insoluble organic matter has been removed from the raw water f is also produced at the same time as concentrated water g is produced. The raw water j is discharged from the insoluble organic matter concentrating section 22 to the outside of the organic matter decomposition system 10A.

[0025] The anaerobic biological treatment unit 24 performs anaerobic biological treatment on the concentrated water g supplied from the insoluble organic matter concentration unit 22, and decomposes the insoluble organic matter contained in the concentrated water g. Also, biogas generated during the decomposition of organic matter can be recovered as energy. The treated water h containing the decomposed organic matter in this way is supplied from the anaerobic biological treatment unit 24 to the post-treatment unit 26.

[0026] The post-treatment unit 26 is, for example, a sedimentation tank or an evaporator, and performs post-treatment on the treated water h supplied from the anaerobic biological treatment unit 24. The post-treatment unit performs the treatment necessary for discharging to the outside of the organic matter decomposition system 10A. For example, in the case of river discharge or sewage discharge, treatment is performed to meet the respective discharge standards. Also, if the purpose is the reuse of treated water, treatment is performed to meet the water quality standards required for reuse. In any case, if the water quality of the treated water h has already reached the required water quality standards, the post-treatment unit is not particularly necessary.

[0027] As described above, according to the organic matter decomposition system 10A of the present embodiment, a membrane such as an MF membrane or a UF membrane is used in the insoluble organic matter concentration unit 22 for the concentration of organic matter. However, before the raw water is introduced into the insoluble organic matter concentration unit 22, the hardness components are removed by the hardness removal unit 16, so that scaling substances are removed. Further, by adding an alkali by the alkali injection unit 20 and increasing the pH, the occurrence of biofouling on the membrane can be avoided.

[0028] Then, by supplying the concentrated water g in which the organic matter is concentrated in the insoluble organic matter concentration unit 22 to the anaerobic biological treatment unit 24, efficient decomposition of the organic matter by anaerobic biological treatment becomes possible in the anaerobic biological treatment unit 24. Anaerobic biological treatment, unlike aerobic biological treatment, does not perform aeration that requires a large amount of power. Thereby, while significantly reducing the power consumption, it becomes possible to efficiently decompose the organic matter. Furthermore, it is also possible to recover biogas by anaerobic biological treatment.

[0029] (Second Embodiment) An organic matter decomposition system according to a second embodiment of the present invention will be described.

[0030] FIG. 2 is a block diagram showing a configuration example of an organic matter decomposition system according to a second embodiment of the present invention.

[0031] The organic matter decomposition system 10B of the second embodiment has a configuration in which a soluble organic matter concentrating section 28 is added to the organic matter decomposition system 10A of the first embodiment. Therefore, the configuration already described in the organic matter decomposition system 10A of the first embodiment will not be described here, and only the differences from the organic matter decomposition system 10A will be described.

[0032] The soluble organic matter concentrating section 28 is a section for concentrating the soluble organic matter contained in the raw water j generated by the insoluble organic matter concentrating section 22, and an RO membrane can be applied for this concentration.

[0033] When an RO membrane is used, the soluble organic matter concentrating unit 28 concentrates the organic matter contained in the raw water j by about 5 to 20 times using the RO membrane. However, the concentration rate is not limited to this range, and depending on the conditions, it is possible to concentrate up to 50 times or 100 times. In addition, since the raw water j has a high pH, ​​the occurrence of silica scaling and biofouling in the RO membrane is avoided.

[0034] The soluble organic matter concentrating section 28 concentrates the organic matter in the raw water j by the RO membrane to generate concentrated water k. The concentrated water k is supplied from the soluble organic matter concentrating section 28 to the anaerobic biological treatment section 24. Meanwhile, the permeated water m, which is the raw water f that has permeated the RO membrane, is discharged from the soluble organic matter concentrating section 28 to the outside of the organic matter decomposition system 10B.

[0035] As a result, in addition to the concentrated water g from the insoluble organic matter concentrating section 22, the concentrated water k from the soluble organic matter concentrating section 28 is also supplied to the anaerobic biological treatment section 24. Therefore, the anaerobic biological treatment section 24 performs anaerobic biological treatment on the concentrated water g and the concentrated water k, and decomposes the soluble organic matter from the concentrated water g and the concentrated water k. The treated water h containing the organic matter decomposed in this manner is supplied from the anaerobic biological treatment section 24 to the post-treatment section 26.

[0036] As described above, according to the organic matter decomposition system 10B of this embodiment, the raw water j discharged from the insoluble organic matter concentrating section 22 is not discharged as it is, but the organic matter is further concentrated by the soluble organic matter concentrating section 28 to generate concentrated water k, and the concentrated water k can also be subjected to anaerobic biological treatment in the anaerobic biological treatment section 24. This can further improve the recovery efficiency of the organic matter. It is preferable to use an RO membrane for the soluble organic matter concentrating section 28, but even if an RO membrane is used for the soluble organic matter concentrating section 28, the raw water j introduced into the RO membrane has hardness components removed by the hardness removing section 16 and has a high pH value due to the supply of alkali e from the alkali injection section 20, so that the occurrence of scaling and biofouling in the RO membrane can be avoided.

[0037] In the above explanation, the concentrated water g from the insoluble organic matter concentrating section 22 and the concentrated water k from the soluble organic matter concentrating section 28 are supplied to the anaerobic biological treatment section 24, but if the organic matter concentration of the concentrated water g from the insoluble organic matter concentrating section 22 is low, the concentrated water g may be discharged outside the organic matter decomposition system 10B and only the concentrated water k may be supplied to the anaerobic biological treatment section 24. In this case, the insoluble organic matter concentrating section 22 will not be able to contribute to the organic matter recovery efficiency, but supplying the raw water j from which solids have been removed to the soluble organic matter concentrating section 28 will contribute to protecting the soluble organic matter concentrating section 28.

[0038] (Third embodiment) An organic matter decomposition system according to a third embodiment of the present invention will be described.

[0039] FIG. 3 is a block diagram showing a configuration example of an organic matter decomposition system according to a third embodiment of the present invention.

[0040] The organic matter decomposition system 10C of the third embodiment is configured by excluding the insoluble organic matter concentrating section 22 from the organic matter decomposition system 10B of the second embodiment. Such a configuration is suitable for cases where the raw water a or the raw water b treated in the solid separation section 14 has a low solid matter content. In the following, the configuration already described in the organic matter decomposition system 10B of the second embodiment will be omitted, and only differences from the organic matter decomposition system 10B will be described.

[0041] That is, in the organic matter decomposition system 10C, the raw water f is supplied to the dissolved organic matter concentrating section .

[0042] As described above, it is preferable to use an RO membrane in the soluble organic matter concentrating section 28. When an RO membrane is used in the soluble organic matter concentrating section 28, the RO membrane concentrates the organic matter contained in the raw water f by about 5 to 20 times to generate concentrated water k. In this embodiment, the concentration rate is not limited to this range either, and depending on the conditions, it is possible to concentrate the raw water f by up to 50 times or 100 times. Furthermore, since hardness components are removed from the raw water f and the pH is increased, the occurrence of scaling and biofouling in the RO membrane is avoided.

[0043] The dissolved organic matter concentrating section 28 supplies the concentrated water k to the anaerobic biological treatment section 24. On the other hand, the permeated water m that has permeated the RO membrane is discharged from the dissolved organic matter concentrating section 28 to the outside of the organic matter decomposition system 10C.

[0044] The anaerobic biological treatment unit 24 performs anaerobic biological treatment on the concentrated water k, and decomposes soluble organic matter contained in the concentrated water k. The treated water h from the concentrated water k in this manner, in which the soluble organic matter has been decomposed, is supplied from the anaerobic biological treatment unit 24 to the post-treatment unit 26.

[0045] As described above, when treating raw water a with a low content of insoluble organic matter, the organic matter decomposition system 10C of this embodiment can be configured to eliminate the insoluble organic matter concentrating section 22. This can simplify the configuration and reduce costs.

[0046] As described above, organic matter decomposition systems 10A to 10C according to the embodiments of the present invention do not perform aerobic biological treatment, but instead concentrate the organic matter in the raw water using a membrane, such as an MF membrane and / or UF membrane in insoluble organic matter concentrating section 22, or an RO membrane in soluble organic matter concentrating section 28, to sufficiently increase the concentration, before performing anaerobic biological treatment. Anaerobic biological treatment can significantly reduce power consumption compared to aerobic biological treatment, and the generated biogas can also be used as energy, making it possible to conserve energy.

[0047] On the other hand, the organic matter decomposition systems 10A to 10C of the embodiment of the present invention do not perform biological treatment at a stage prior to the membrane (for example, the insoluble organic matter concentrating section 22 and the soluble organic matter concentrating section 28), so that wastewater with high biodegradability passes through the membrane. In general, not performing biological treatment at a stage prior to the membrane increases the risk of biofouling occurring in the membrane. However, the organic matter decomposition systems 10A to 10C of the embodiment of the present invention can avoid the occurrence of scaling and biofouling in the membrane by removing hardness components from the raw water at a stage prior to the membrane, removing scaling substances, and further increasing the pH of the raw water by adding alkali to the raw water, thereby increasing the solubility of silica. Note that if the pH is increased without removing the hardness components, the hardness components easily cause scaling, so it is essential to remove the hardness components before increasing the pH.

[0048] The organic matter decomposition systems 10A to 10C according to the embodiments of the present invention can be applied to wastewater recycling and zero-discharge (ZLD) systems, in addition to wastewater treatment aimed at external discharge.

[0049] Furthermore, the organic matter decomposition systems 10A to 10C according to the embodiments of the present invention are applicable not only to the high concentration of organic matter in wastewater, but also to the high concentration of beverages, seasonings, organic chemicals, and the like.

[0050] Although some 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 embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0051] 10A, 10B, 10C Organic matter decomposition system 12 Raw water supply tank 14 Solid separation section 16 Hardness removal part 18 Carbon dioxide removal section 20 Alkaline injection section 22 Insoluble organic matter concentration section 24 Anaerobic biological treatment unit 26 Post-processing section 28 Soluble organic matter concentration section

Claims

1. a hardness removal unit that removes hardness components from the raw water to be treated; a carbon dioxide removal unit that removes carbon dioxide components from the raw water from which the hardness components have been removed; an alkali injection unit that injects alkali into the raw water from which the carbon dioxide components have been removed; an insoluble organic matter concentration unit for concentrating insoluble organic matter contained in the raw water into which the alkali has been injected; an anaerobic biological treatment section that performs anaerobic biological treatment on the raw water in which the insoluble organic matter is concentrated, and decomposes the insoluble organic matter; An organic matter decomposition system equipped with

2. The method further includes a soluble organic matter concentration unit that concentrates soluble organic matter contained in the raw water from which the insoluble organic matter has been removed by the insoluble organic matter concentration unit, The anaerobic biological treatment unit performs the anaerobic biological treatment on the raw water in which the soluble organic matter is concentrated, and decomposes the soluble organic matter. The organic matter decomposition system according to claim 1.

3. a hardness removal unit that removes hardness components from the raw water to be treated; a carbon dioxide removal unit that removes carbon dioxide components from the raw water from which the hardness components have been removed; an alkali injection unit that injects alkali into the raw water from which the carbon dioxide components have been removed; an insoluble organic matter concentration unit for concentrating insoluble organic matter contained in the raw water into which the alkali has been injected; a soluble organic matter concentrating unit that concentrates soluble organic matter contained in the raw water from which the insoluble organic matter has been removed by the insoluble organic matter concentrating unit; an anaerobic biological treatment section that performs anaerobic biological treatment on the raw water in which the soluble organic matter is concentrated, thereby decomposing the soluble organic matter; An organic matter decomposition system equipped with

4. a hardness removal unit that removes hardness components from the raw water to be treated; a carbon dioxide removal unit that removes carbon dioxide components from the raw water from which the hardness components have been removed; an alkali injection unit that injects alkali into the raw water from which the carbon dioxide components have been removed; a soluble organic matter concentration unit for concentrating soluble organic matter contained in the raw water into which the alkali has been injected; an anaerobic biological treatment section that performs anaerobic biological treatment on the raw water in which the soluble organic matter is concentrated, thereby decomposing the soluble organic matter; An organic matter decomposition system equipped with

5. The organic matter decomposition system according to claim 1 , wherein the insoluble organic matter concentrating section is provided with an MF membrane or an UF membrane.

6. The organic matter decomposition system according to claim 2 , wherein the soluble organic matter concentrating section includes a reverse osmosis membrane.

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