Method and apparatus for reducing the color of water

Abstract

The system significantly reduces the color of water, maintains this color reduction performance stably over a long period, reduces the frequency of maintenance, and lowers both initial and running costs. [Solution] In a method for reducing the color of water treated in a septic tank, the immersion step of soaking a color component adsorbent 10 such as allophane-containing soil in the water and the drainage step of draining the water from the color component adsorbent 10 and exposing the color component adsorbent 10 to the air are alternately repeated using an autosiphon such as a bell siphon 7.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for reducing the chromaticity of water.

Background Art

[0002] The applicant of the present application has implemented a sewage purification treatment apparatus and method using soil having an aggregate structure, containing organic matter and having an allophane content of 20 to 39% in a dry state, as described in Patent Document 1. The use of purifying the drainage of toilets and the like and reusing it as toilet washing water and the like has been spreading.

[0003] However, in this purification treatment apparatus and method, the treatment capacity per unit area of soil is not very high, so a large area is required. Also, when increasing the water volume load per unit area, the soil becomes anaerobic and clogs, the treatment function deteriorates, and a large amount of color components may remain in the treated water and the chromaticity may increase. [[ID=十七]]

[0004] Also, as described in Patent Document 2, there is a method of highly treating the water treated in a relatively compact purification tank with a parallel tertiary treatment apparatus and further removing color components through an activated carbon filter.

[0005] However, this method becomes a complicated treatment, and the treatment performance cannot be maintained unless maintenance management is frequently carried out. Also, in order to maintain the chromaticity of the treated water low, the replacement frequency of the activated carbon also increases, and the running cost is high.

[0006] Here, the chromaticity of water is the degree of yellowish to yellowish brown exhibited by dissolved substances and colloidal substances contained in water. In this specification, the chromaticity of water was measured by a chromaticity sensor CR-30 manufactured by Kasa原理 Chemical Industry Co., Ltd.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] Therefore, the objective of the present invention is to significantly reduce the chromaticity of water, maintain this chromaticity reduction performance stably over a long period of time, reduce the frequency of maintenance, and lower both the initial cost and running cost. [Means for solving the problem]

[0009] [1] In a method for reducing the color of water, A method for reducing the chromaticity of water, characterized by alternately repeating a soaking step in which a color component adsorbent is immersed in the aforementioned water, and a draining step in which the water is discharged from the color component adsorbent and the color component adsorbent is exposed to the air.

[0010] <effect> In the immersion step, the color components in the colored water are adsorbed onto the color component adsorbent. In the drainage step, aerobic microorganisms inhabit the color component adsorbent, enabling advanced treatment of color components and other organic matter. By repeating both steps alternately, the color reduction treatment proceeds efficiently. As will be described later (Example 3), in addition to the color component, one or more of the turbidity component, biochemical oxygen demand (BOD), and suspended solids (SS) may be adsorbed by the color component adsorbent or treated by microorganisms residing in the color component adsorbent. In other words, the present invention is not limited to a reduction in chromaticity alone, but also includes cases in which one or more of the turbidity component, BOD, and SS are reduced in addition to the reduction in chromaticity.

[0011] [2] The method for reducing the color of water as described in [1], wherein the immersion step and the draining step are repeated alternately using an autosiphon. <effect> Using an autosiphon allows for structural simplification and energy savings. Furthermore, the color component adsorbent can maintain a stable granular state without being destroyed by the flow rate generated by the autosiphon, and clogging does not occur.

[0012] [3] The method for reducing the color of water according to [2], wherein the autosiphon is a bell siphon or a U siphon.

[0013] [4] A method for reducing the color of water as described in any one of the items [1] to [3], wherein the water whose color is reduced is water that has been treated in a septic tank.

[0014] [5] A method for reducing the chromaticity of water according to any one of the following items [1] to [3], wherein the color component adsorbent is allophane-containing soil.

[0015] [6] In a device for reducing the color of water, A water color reduction device equipped with an autosiphon that alternately repeats an immersion step of soaking a color component adsorbent in the aforementioned water and a drainage step of discharging the water from the color component adsorbent and exposing the color component adsorbent to air.

[0016] [7] The water color reduction device described in [6], wherein the autosiphon is a bell siphon or a U siphon.

[0017] [8] A device for reducing the color of water according to [6] or [7], wherein the color component adsorbent is allophane-containing soil.

[0018] [9] A water color reduction device according to any one of the items [6] to [8], comprising two or more water color reduction devices connected in series. By equipping the system with two or more water chromaticity reduction devices in series, a more advanced chromaticity reduction treatment can be performed. [Effects of the Invention]

[0019] According to the present invention, it is possible to highly reduce the chromaticity of water, maintain the chromaticity reduction performance stably over a long period of time, reduce the frequency of maintenance management, and achieve excellent effects of reducing the introduction cost and running cost.

Brief Description of Drawings

[0020] [Figure 1] FIG. 1 shows the water chromaticity reduction device of Example 1, where (a) is a side view, and (b) to (e) are diagrams for explaining the operation of the bell siphon. [Figure 2] FIG. 2 is a graph showing the change in water chromaticity over time in Example 1. [Figure 3] FIG. 3(a) is a side view of the water chromaticity reduction device of Example 2, and (b) is a side view of the water chromaticity reduction device of the comparative example. [Figure 4] FIG. 4 is a side view of the water chromaticity reduction device of Example 3. [Figure 5] FIG. 5 is a side view of the water chromaticity reduction device (using a U siphon) of the modified example.

Embodiments for Carrying Out the Invention

[0021] 1. Auto siphon An auto siphon is a siphon that can automatically repeat the rise and fall of the water level. Although not particularly limited, examples include a bell siphon, a U siphon, etc.

[0022] 2. Color component adsorbent A color component adsorbent adsorbs the color components contained in the colored water. Although not particularly limited, examples include allophane-containing soil, activated carbon, etc. As the allophane-containing soil, although not particularly limited, examples include black volcanic ash soil, red jade soil, etc. The allophane content of the allophane-containing soil is not particularly limited, but it is preferably 8% by mass or more in the dry state.

[0023] For color component adsorbents, granular form is preferable because it allows for easier exposure to air during the drainage step. Therefore, in the case of allophane-containing soil, granular form is preferable. Activated carbon is generally available in granular form. The particle size of the color component adsorbent is not particularly limited, but 1 to 10 mm is preferred.

[0024] In the case of allophane-containing soil, calcined soil is preferable. This is because calcination increases the strength of the granular adsorbent, preventing it from collapsing when water is absorbed.

[0025] 3. Time allocation The time allocation between the immersion step and the drainage step is not particularly limited, but an example is to alternate between an immersion step of 1 to 10 minutes and a drainage step of 1 to 10 minutes. This example makes it easier to maintain high chromaticity reduction performance stably over a long period of time. [Examples]

[0026] Embodiments of the present invention will be described with reference to the drawings. Note that the structures, materials, numerical values, shapes, and dimensions described in the embodiments are illustrative and can be modified as appropriate without departing from the spirit of the invention.

[0027] [Example 1] In Example 1, the color component adsorbents 10 for samples 1 to 6 were separately set in the small-scale chromaticity reduction device 1 shown in Figure 1, and the processing performance was confirmed.

[0028] The chromaticity reduction device 1 of Example 1 consists of a treatment water tank 2 installed relatively below and a treatment tank 5 installed relatively above.

[0029] The treatment tank 2 stores the water to be treated, supplies the water to the treatment tank 5, and stores the water that has been treated in the treatment tank 5 again. In this example, the treatment tank 2 consists of a simple treatment tank container 3 with an open top and a pump 4 installed inside the treatment tank container 3. Water is supplied to the treatment tank 5 by the pump 4 and the piping extending from it. The treatment tank container 3 has a capacity of 15L.

[0030] Treatment tank 5 is used to reduce the color of water. The treatment tank 5 in this example comprises a simple treatment tank container 6 with an open top, a bell siphon 7 attached to the treatment tank container 6, and a color component adsorbent 10 filled in the treatment tank container 6. A 10L bucket was used as the treatment tank container 6.

[0031] The bell siphon 7 repeatedly operates by filling the treatment tank 5 with supplied water up to a predetermined level, and then discharging almost all of the stored water to the outside. The bell siphon 7 in this example is equipped with a relatively small-diameter inner overflow tube 8 and a relatively large-diameter outer bell tube 9, arranged concentrically. The overflow pipe 8 has its upper end open inside the treatment tank 5 and its lower end open below the treatment tank 5 (and above the treated water tank 2), and is supported by being inserted into a support pipe that is fixed through the bottom surface of the treatment tank 5. The bell pipe 9 is placed over the outer circumference of the overflow pipe 8 inside the processing tank 5, and its upper end is closed with a cap. The lower end of the bell pipe 9 has an inlet. Examples of inlets include the gap between the lower end of the bell pipe 9 and the bottom surface of the treatment tank 5, or a hole drilled through the lower end of the bell pipe 9. There is a gap between the inner surface of the bell pipe 9 and the outer surface of the overflow pipe 8. There is an overflow gap between the underside of the cap of the bell pipe 9 and the upper end opening of the overflow pipe 8.

[0032] The operation of the bell siphon 7 will be explained with reference to Figures 1(b) to 1(e). Water is continuously supplied from the treatment tank 2 to the treatment tank container 6, and as shown in (b), the supplied water flows into the gap between the pipes from the inlet of the bell pipe 9, so that the water level in the treatment tank container 6 and the water level in the gap between the pipes rise equally. As shown in (c), when the water level in the gap between the pipes rises above the upper opening of the overflow pipe 8, water gradually flows into the overflow pipe 8 from the upper opening, and drainage begins. Then, when the water level in the gap between the pipes reaches the bottom surface of the cap of the bell pipe 9, that is, when the overflow gap is filled with water and the air is released, drainage by siphon begins. Since the wastewater discharged by the siphon is greater than the water supplied from the treatment tank 2, as shown in (d), the water level in the treatment tank container 6 decreases, but the overflow gap remains filled with water and the water level in the pipe gap does not decrease. As shown in (e), when the water level in the treatment tank container 6 falls below the inlet level, air flows from the inlet into the gap between the pipes, causing the water level in the gap between the pipes to drop rapidly, and the water in the overflow pipe 8 to be drained all at once. The drained water then returns to the treatment tank container 6 and is circulated. Subsequently, as described above, water is continuously supplied from the treatment tank 2 to the treatment tank container 6. When the water level in the treatment tank container 6 rises above the inlet, the process returns to (b) above, and steps (b) to (e) are repeated.

[0033] Then, the time from when the water level in the treatment tank container 6 rises in (b) and the color component adsorbent 10 is fully immersed, until the water is drained all at once in (e), is, for example, 4 minutes. This time is the immersion step in which the color component adsorbent 10 is immersed in water, and the color reduction treatment by adsorption of color components takes place. Also, the time from when the water is drained all at once in (e) until the color component adsorbent 10 is fully immersed, until (b), is, for example, 1 minute. This time is the drainage step in which the color component adsorbent 10 is exposed to air, making it easier for aerobic microorganisms to inhabit the color component adsorbent 10.

[0034] The color component adsorbents 10 of samples 1 to 6 shown in Table 1 were separately filled into the treatment tank container 6 for the experiment.

[0035] [Table 1]

[0036] Sample 1 is hard akadama soil made from volcanic ash soil from Kanuma (product name "Natural Filtered Akadama Soil, Small Grain" manufactured by GEX Corporation). Sample 2 is soil that has been granulated and fired from Kanuma black soil (product name "BestBioSand" manufactured by GEX Corporation). Sample 3 is soil from Nishihara Village, Kumamoto Prefecture, which was produced by granulating and firing red soil mixed with black soil. The firing temperature was 250°C. Sample 4 is pulverized activated carbon made from coconut shells (product name "Granular Activated Carbon, Pulverized Carbon" manufactured by Futamura Chemical Co., Ltd.). Sample 5 is a soil made from Kuroboku soil from Tottori Prefecture, which has been granulated and fired. The firing temperature was 250°C. Sample 6 is a type of soil from Mie Prefecture that has been granulated and fired. The firing temperature was 250°C. Table 1 shows the particle size and allophane content of each sample. While the allophane content is based on the raw material analysis, the fired clay is nearly dry, and all samples have an allophane content of 8% by mass or more in their dry state.

[0037] <Experimental Method> Approximately 4 liters of the color component adsorbent 10 for each sample 1 to 6 was placed in a mesh bag with a mesh size of about 1 mm and then filled into the treatment tank container 6. The raw water used for the test was water treated in a single-treatment septic tank (not shown). The color of the water used for samples 1-3 was 81.4 degrees, and the color of the water used for samples 4-6 was 78.2 degrees, both exhibiting a similar brownish hue. 12 liters of this water was stored in the treatment tank container 3, and as described above, it was continuously supplied to the treatment tank container 6 by pump 4. The water was then circulated by alternating between a 4-minute immersion step and a 1-minute drainage step using the bell siphon 7, as described above, to confirm the performance of reducing color.

[0038] <Experimental Results> The change in the color of water over time is shown in Table 1 and Figure 2. In all cases using samples 1-6, a clear decrease in chromaticity was observed after 1 hour, and the chromaticity continued to decrease over time, confirming the chromaticity reduction performance. Since the decrease in chromaticity was particularly rapid when using samples 1 and 3, we decided to use sample 3 in the following examples 2 and 3.

[0039] [Example 2] In Example 2, the color component adsorbent 10 of sample 3 was set in the medium-scale chromaticity reduction apparatus 1 shown in Figure 3(a), and in the Comparative Example, it was set in the chromaticity reduction apparatus 21 shown in Figure 3(b), and the processing performance was compared.

[0040] As shown in Figure 3(a), the chromaticity reduction device 1 of Example 2 consists of a treatment water tank 2 installed relatively below and a treatment tank 5 installed relatively above. The chromaticity reduction device 1 has basically the same structure as the chromaticity reduction device 1 of Example 1, except that the capacity of the treatment water container 3 is approximately 60L and the capacity of the treatment tank container 6 is approximately 36L. Therefore, the same reference numerals as in Example 1 are used in Figure 3 and the explanation is omitted.

[0041] As shown in Figure 3(b), the comparative example chromaticity reduction device 21 consists only of a treatment tank 25, which comprises a treatment tank container 26 and a water inlet pipe 27. The capacity of the treatment tank container 26 is approximately 36 L.

[0042] <Experimental Method> The color component adsorbent 10 of sample 3 was divided into several mesh bags with a mesh size of approximately 1 mm in amounts of 3 to 5 L, and then filled into the treatment tank container 6 of Example 2 and the treatment tank container 26 of the Comparative Example, respectively. The raw water used in the test was treated water from a septic tank (not shown) in an office building with a high volume of toilet wastewater. Its color was 40 degrees, and it exhibited a reddish-brown color. In Example 2, approximately 40 liters of the water was stored in the treatment tank container 3 and continuously supplied to the treatment tank container 6 by a pump. The water was then circulated by alternating between a 5-minute immersion step and a 2-minute drainage step using a bell siphon 7, and the ability to reduce color was investigated. In the comparative example, approximately 40 liters of the water were stored in the treatment tank container 26, and the color component adsorbent 10 was immersed in it (immersion water flow method) to investigate the ability to reduce chromaticity.

[0043] <Experimental Results> Table 2 shows the daily changes in the color of water.

[0044] [Table 2]

[0045] In the comparative example, the water initially had low color and was almost colorless and transparent, but its color increased over time, approaching that of the raw water. This is thought to be due to the accumulation of a biofilm on the mesh bag over time, making it difficult for the water to come into contact with the color component adsorbent 10 inside the mesh bag. On the other hand, in Example 2, the treated water consistently had low coloration throughout the experimental period, resulting in nearly colorless and transparent treated water.

[0046] [Example 3] In Example 3, the color component adsorbent 10 of sample 3 was placed in the large-scale chromaticity reduction apparatus shown in Figure 4, and the processing performance was confirmed.

[0047] As shown in Figure 4, the chromaticity reduction device of Example 3 is equipped with two or more in series configurations of a first chromaticity reduction device 1a, which consists of a first treatment tank 2a installed relatively below and a second treatment tank 5a installed relatively above, and a second chromaticity reduction device 1b, which consists of a similar second treatment tank 2b and second treatment tank 5b. In other words, the water in the first treatment tank 2a, whose chromaticity has been reduced by the first chromaticity reduction device 1a, is supplied to the second treatment tank 2b, where its chromaticity is further reduced by the second chromaticity reduction device 1b. Each chromaticity reduction device 1a and 1b has basically the same structure as the chromaticity reduction device 1 of Example 1, except that the capacity of each treatment tank container 3a and 3b is approximately 105L, and the capacity of each treatment tank container 6a and 6b is approximately 100L. Therefore, the same reference numerals as in Example 1 are used in Figure 4, and their explanation is omitted.

[0048] <Experimental Method> The color component adsorbent 10 of sample 3 was divided into several mesh bags with a mesh size of approximately 1 mm in amounts of 3 to 5 L, and then filled into the respective treatment tank containers 6a and 6b. The raw water used in the test was treated water from a septic tank (not shown) in an office building with a high volume of toilet wastewater. Its color was 38 degrees, exhibiting a reddish-brown color. The water was intermittently supplied to the first treatment tank container 3a about once an hour (approximately 95 L) (treatment volume 180 L / day), and continuously supplied to the first treatment tank container 6a at 10 L / min by pump 4. The water was circulated by the bell siphon 7, which alternately repeated an immersion step of 6 minutes and a drainage step of 4 minutes. The water in the first treatment tank 2a was supplied to the second treatment tank 2b, and similarly supplied to the second treatment tank container 6b by pump 4. The water was circulated by the bell siphon 7, which alternately repeated an immersion step and a drainage step, and a decrease in the color and other properties of the treated water discharged from the second treatment tank 2b was confirmed.

[0049] <Experimental Results> Table 3 shows the color, turbidity, biochemical oxygen demand (BOD), and suspended solids (SS) of the raw water used in the test and the treated water 6 months after the start of treatment.

[0050] [Table 3]

[0051] Turbidity was measured according to the Water Supply Test Method (2020), BOD according to JIS K0102-21 and 32.3, and SS according to Appendix 9 of Environmental Notification No. 59 of 1971. In Example 3, in addition to a decrease in color, the decrease in turbidity, BOD, and SS was stably maintained over a long period of time. For treated water to be reused as toilet flushing water, it is preferable that the SS is 5 mg / L or less, the color is 20 degrees or less, and the turbidity is 2 degrees or less, and the treated water in Example 3 met these conditions.

[0052] It should be noted that the present invention is not limited to the embodiments described above, and can be appropriately modified and implemented without departing from the spirit of the invention. (1) Replace the bell siphon 7 in the above embodiment with a U-siphon 11 as shown in the modified example in Figure 5. This modified example will also provide basically the same effects as the embodiment. (2) Water other than water treated in a septic tank, such as water treated in a septic tank treatment device like the one described in Patent Document 1, is treated with the color reduction method and apparatus of the present invention. [Explanation of Symbols]

[0053] 1 Chromaticity reduction device 2 Treatment tank 3. Treatment tank container 4 pumps 5. Treatment tank 6. Processing tank container 7 Versiphon 8. Overflow pipe 9 Bell pipes 10 Color Component Adsorbent 11 U-Siphon

Claims

1. In a method for reducing the color of water, A method for reducing the chromaticity of water, characterized by alternately repeating a soaking step in which a color component adsorbent is immersed in the aforementioned water, and a draining step in which the water is discharged from the color component adsorbent and the color component adsorbent is exposed to the air.

2. A method for reducing the color of water according to claim 1, wherein an immersion step and a draining step are alternately repeated using an autosiphon.

3. The method for reducing the color of water according to claim 2, wherein the autosiphon is a bell siphon or a U siphon.

4. A method for reducing the color of water according to any one of claims 1 to 3, wherein the water whose color is reduced is water that has been treated in a septic tank.

5. A method for reducing the chromaticity of water according to any one of claims 1 to 3, wherein the color component adsorbent is allophane-containing soil.

6. In a device for reducing the color of water, A water color reduction device equipped with an autosiphon that alternately repeats an immersion step of soaking a color component adsorbent in the aforementioned water and a drainage step of draining the water from the color component adsorbent and exposing the color component adsorbent to air.

7. The water color reduction device according to claim 6, wherein the autosiphon is a bell siphon or a U siphon.

8. The water color reduction device according to claim 6 or 7, wherein the color component adsorbent is allophane-containing soil.

9. The water color reduction device according to claim 6 or 7, comprising two or more water color reduction devices connected in series.

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