Water treatment apparatus and water treatment method

Abstract

To reduce the volume of oil and fat sludge by culturing and activating microorganisms with energy consumption smaller than that in the conventional technique.SOLUTION: There are provided a treatment tank 2 for receiving and storing water containing oil and fat, a culture tank 3 for culturing microorganisms having oil and fat degradation ability, a first water supply channel 4 for sending water stored in the treatment tank 2 to the culture tank 3, a second water supply channel 5 for sending water stored in the culture tank 3 to the treatment tank 2, and an ultrafine air bubble supply device 6 for supplying ultrafine air bubbles to at least one of the treatment tank 2, the culture tank 3, the first water supply channel 4, and the second water supply channel 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water treatment device and a water treatment method. [Background technology]

[0002] When wastewater discharged from a factory or the like contains oil and fat, the oil and fat may interfere with biological water treatment such as activated sludge treatment. Therefore, facilities that discharge oil-containing wastewater widely use pressurized flotation separators to separate oil and fat from wastewater prior to biological water treatment. However, the oil and fat separated by this type of equipment becomes oil-containing sludge and must be treated as industrial waste.

[0003] Technologies for decomposing oils and fats have been studied to reduce the amount of oil-containing sludge generated. For example, International Publication No. 2019 / 098255 (Patent Document 1) and International Publication No. 2013 / 137010 (Patent Document 2) disclose methods for decomposing oils and fats using microorganisms capable of decomposing oils and fats. In the invention described in Patent Document 1, microorganisms cultured in a microbial culture tank are supplied to an oil and fat decomposition tank, where the oils and fats in the wastewater are decomposed. In the invention described in Patent Document 2, a treatment agent containing microorganisms is added to a treatment tank to decompose the oils and fats in the wastewater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 098255 [Patent Document 2] International Publication No. 2013 / 137010 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the inventions described in Patent Documents 1 and 2 only supply microorganisms to the site where fats and oils are decomposed, and do not sufficiently consider enhancing the activity of microorganisms in the site where fats and oils are decomposed. There is also room for consideration regarding the reduction of energy consumption of the entire device.

[0006] Therefore, it is desirable to realize a water treatment device and a water treatment method that can culture and activate microorganisms with less energy consumption than conventional techniques, thereby reducing the volume of oil and fat sludge. [Means for solving the problem]

[0007] The water treatment device according to the present invention is characterized by comprising: a treatment tank that receives and stores water containing oils and fats; a culture tank that cultures microorganisms having the ability to decompose oils and fats; a first water supply channel that sends the water stored in the treatment tank to the culture tank; a second water supply channel that sends the water stored in the culture tank to the treatment tank; and an ultrafine bubble supply device that supplies ultrafine bubbles to at least one of the treatment tank, the culture tank, the first water supply channel, and the second water supply channel.

[0008] The water treatment method according to the present invention is characterized by comprising receiving and storing water containing oils and fats in a treatment tank, culturing microorganisms having the ability to decompose oils and fats in a culture tank, transferring the water containing the oils and fats from the treatment tank to the culture tank, transferring water containing the microorganisms from the culture tank to the treatment tank, and supplying ultrafine bubbles to at least one location in a water path including the treatment tank and the culture tank.

[0009] According to the above-mentioned configuration, when decomposing oils and fats by the action of microorganisms, ultrafine bubbles are used to promote the cultivation of microorganisms and the emulsification of oils and fats, so the volume of oil and fat sludge can be reduced with less energy consumption than conventional techniques. Furthermore, if the water to be treated contains nutrients that can be used by microorganisms, these can be used to cultivate the microorganisms, so the addition of nutrients etc. is not required, or only a very small amount of nutrients etc. is sufficient.

[0010] Preferred embodiments of the present invention will be described below, but the scope of the present invention is not limited to the preferred embodiments described below.

[0011] In one aspect of the water treatment device according to the present invention, the ultrafine bubble supplying device preferably supplies the ultrafine bubbles to at least the culture tank.

[0012] According to this configuration, since ultrafine bubbles are supplied directly to the culture tank, the culture of microorganisms in the culture tank can be easily promoted.

[0013] In one aspect of the water treatment device according to the present invention, the ultrafine bubble supply device preferably includes a cavitation type bubble generation device.

[0014] This configuration makes it easier to generate particularly fine bubbles. The smaller the bubbles, the easier they are to maintain in the water, which makes it easier for microorganisms to maintain activity, especially in the treatment tank. Oil is also more easily broken down into fine particles, improving the efficiency of oil decomposition.

[0015] In one aspect of the water treatment device according to the present invention, the culture tank preferably has an agitator including a hyperboloid-shaped agitator blade.

[0016] According to this configuration, the stirring efficiency in the culture tank is good, and the culture of microorganisms progresses easily.

[0017] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which is given with reference to the drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating a configuration of a water treatment device according to an embodiment. [Figure 2] 1 is a block diagram showing a configuration of a water treatment method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of a water treatment device and a water treatment method according to the present invention will be described with reference to the drawings. In the following, an example will be described in which the water treatment device and the water treatment method according to the present invention are applied to a water treatment device 1 that treats organic wastewater containing n-hexane extracts at a business facility that discharges the organic wastewater, and a water treatment method using the same.

[0020] [Configuration of water treatment device] The water treatment device 1 according to this embodiment includes a treatment tank 2, a culture tank 3, a first water conveyance channel 4, a second water conveyance channel 5, and an ultrafine bubble supplying device 6 (FIG. 1). The water treatment device 1 receives organic wastewater containing oils and fats (an example of water containing oils and fats), decomposes the oils and fats, and then sends the treated water to a downstream wastewater treatment facility. The decomposition of oils and fats is carried out by the action of microorganisms, and microorganisms cultured in the culture tank 3 decompose the oils and fats in the treatment tank 2. The components produced by the decomposition of the oils and fats are treated in the downstream wastewater treatment facility. The downstream wastewater treatment facility may be a facility that performs known biological water treatment, such as an activated sludge process, an aerobic filter process, an upflow anaerobic sludge bed process (UASB), or an anaerobic filter process.

[0021] The treatment tank 2 is a tank that receives and stores organic wastewater containing oils and fats (one example of water containing oils and fats), and the culture tank 3 is a tank that cultures microorganisms that have the ability to decompose oils and fats. The treatment tank 2 and the culture tank 3 are connected by a first water conveyance channel 4 and a second water conveyance channel 5, which form a circulation path C. In this embodiment, the capacity of the treatment tank 2 is larger than the capacity of the culture tank 3. The treatment tank 2 is fluidly connected to a downstream wastewater treatment facility, and a portion of the water stored in the treatment tank 2 flows out into the wastewater treatment facility.

[0022] The culture tank 3 has a tank body 31, an agitator 32, and a chemical supply device 33. The tank body 31 is a tank that is in fluid communication with the treatment tank 2 via the first water supply channel 4 and the second water supply channel 5, and serves as a place to accommodate the water received from the treatment tank 2 and to culture microorganisms. The tank body 31 may be provided with various devices as ancillary equipment for realizing an environment suitable for culturing microorganisms, such as a temperature control device for adjusting the water temperature and a pH adjuster feeding device for adjusting the pH. Note that these ancillary equipment may be known and are not shown.

[0023] The agitator 32 has an agitator blade 34 and a motor 35 that drives it. A hyperboloid-shaped agitator blade 34 is preferable because it improves agitation efficiency and facilitates microbial cultivation. An example of an agitator 32 having a hyperboloid-shaped agitator blade 34 is Pabiomix (registered trademark) (manufactured by Kobelco Eco-Solutions Co., Ltd.). The motor 35 may be a known motor used in agitators, and the specifications of the motor 35 can be determined taking into consideration the dimensions and shape of the tank body 31 and the agitator blade 34.

[0024] The chemical supply device 33 is a device that supplies chemicals to the tank body 31. In this embodiment, microorganisms with the ability to decompose oils and fats are introduced into the culture tank 3 as a microbial preparation. To assist the microorganisms in decomposing oils and fats, an oil and fat treatment agent that micronizes the oils and fats dispersed in water is also used. To accommodate the introduction of these chemicals, two chemical supply devices 33 (33A, 33B) are provided in this embodiment. The chemical supply device 33A introduces the microbial preparation, and the chemical supply device 33B introduces the oil and fat treatment agent into the culture tank 3. Each chemical supply device may have components such as a tank for storing the chemical, a pump for sending the chemical to the culture tank 3, a valve for controlling the flow of the chemical, and piping connecting the tank and the culture tank 3, but these are shown in a simplified form in FIG. 1.

[0025] The microorganisms to be cultured in the culture tank 3 are not limited as long as they are microorganisms having the ability to decompose fats and oils. Examples of such microorganisms include Bacillus subtilis, bacillus (genus Acinetobacter), yeast, etc. Furthermore, the microbial preparation containing the microorganisms having the ability to decompose fats and oils is not particularly limited, and for example, commercially available products can be used.

[0026] The oil and fat treatment agent added to the culture tank 3 is a chemical that serves to atomize the oil and fat dispersed in water, and includes, for example, a surfactant. By atomizing the oil and fat, the specific surface area of ​​the oil and fat increases, which makes it easier for microorganisms to decompose the oil and fat on the surface of the oil and fat. Examples of the oil and fat treatment agent include, but are not limited to, a grease trap oil decomposer and an oil and fat emulsifier.

[0027] The first water supply channel 4 is a channel for supplying water contained in the treatment tank 2 to the culture tank 3. The power for supplying water in the first water supply channel 4 is arbitrary, and for example, water may be supplied by a pump or the like, or water may be supplied by utilizing the difference in elevation between the treatment tank 2 and the culture tank 3. The first water supply channel 4 may be a channel of any shape, such as a tubular or groove-like shape, and does not have to be the same shape throughout.

[0028] The second water supply channel 5 is a channel for supplying the water contained in the culture tank 3 to the treatment tank 2. The power for supplying water in the second water supply channel 5 is arbitrary, and for example, the water may be supplied by a pump or the like, or the water may be supplied by utilizing the difference in elevation between the treatment tank 2 and the culture tank 3. The second water supply channel 5 may be a channel of any shape, such as a tubular or groove-like shape, and does not have to be the same shape throughout.

[0029] The second water supply channel 5 has branches 51, one of which is connected to the treatment tank 2 and the other of which is connected to the ultrafine bubble supply device 6. A pump 52 for sending water to the ultrafine bubble supply device 6 is provided downstream of the branch 51 and upstream of the ultrafine bubble supply device 6.

[0030] The ultrafine bubble supply device 6 is a device that generates ultrafine bubbles (one example of ultrafine bubbles) in water and supplies them to the culture tank 3. Ultrafine bubbles are defined in ISO 20480-1:2017 and JIS B 8741-1:2019 as bubbles with a volume-equivalent diameter of less than 1 μm. Because ultrafine bubbles are so small in size, the buoyancy that tries to raise the bubbles in water and the downward resistance that the bubbles experience from the water as they try to rise are at the same level. This gives ultrafine bubbles the property of being difficult to rise and difficult to disappear.

[0031] The ultrafine bubble supplying device 6 is not limited as long as it is a device that can generate ultrafine bubbles in water, and may include bubble generators of known types such as a cavitation type, a surfactant-added micropore type, a pressurized dissolution type, a high-speed swirling liquid flow type, etc. It is preferable that the ultrafine bubble supplying device 6 includes a cavitation type bubble generator, since it is particularly easy to generate fine bubbles and to maintain the ultrafine bubbles in water.

[0032] The ultrafine bubble supplying device 6 has its primary side connected to the pump 52 of the second water supply channel 5, and water is supplied from the culture tank 3 via a branch 51 of the second water supply channel 5 and the pump 52. The water flowing out from the secondary side of the ultrafine bubble supplying device 6 contains ultrafine bubbles and flows into the tank body 31 of the culture tank 3. In the tank body 31, microorganisms grow using the oxygen contained in the ultrafine bubbles.

[0033] [Water treatment method] The water treatment method according to this embodiment includes receiving and storing organic wastewater containing oils and fats in the treatment tank 2 (step S10), culturing microorganisms capable of decomposing oils and fats in the culture tank 3 (step S20), transferring the organic wastewater containing oils and fats from the treatment tank 2 to the culture tank 3 (step S30), transferring water containing the microorganisms from the culture tank 3 to the treatment tank 2 (step S40), and supplying ultra-fine bubbles to the culture tank 3 (step S50) (FIG. 2). For convenience, steps S10 to S50 will be described with names and symbols assigned, but steps S10 to S50 proceed in parallel in each part of the water treatment device 1.

[0034] The treatment tank 2 receives and stores organic wastewater containing oils and fats discharged from a business establishment (Step S10). A portion of this organic wastewater is sent to the culture tank 3 via the first water conveyance channel 4 (Step S30). In the culture tank 3, a microbial preparation, an oil treatment agent, and ultrafine bubbles are supplied to the organic wastewater (Step S50), and microorganisms are cultured using the oxygen contained in the ultrafine bubbles (Step S20). The water to which the microorganisms have been cultured in the culture tank 3 and to which the oil treatment agent and ultrafine bubbles have been added is sent to the treatment tank 2 via the second water conveyance channel 5 (Step S40).

[0035] In steps S10 to S50, microorganisms (microbial preparations), an oil and fat treatment agent, and ultrafine bubbles are added to organic wastewater containing oil and fat, and this mixture is circulated through circulation path C. As mentioned above, ultrafine bubbles are resistant to disappearance and are easily maintained during circulation. Therefore, a state in which ultrafine bubbles are present in the water not only in the culture tank 3 immediately after supply from the ultrafine bubble supply device 6, but also in the treatment tank 2, first water conveyance path 4, and second water conveyance path 5 can be achieved. This increases the activity of microorganisms in all parts of circulation path C, enabling oil and fat to be decomposed throughout the entire circulation path C.

[0036] A non-limiting example of a method for adjusting the supply amount of ultra-fine bubbles in step S50 is a method based on the dissolved oxygen concentration of the water circulating through the circulation path C. For example, a dissolved oxygen concentration meter is installed in at least one of the treatment tank 2 and the culture tank 3, and the pump 52 is operated to maintain the dissolved oxygen concentration that maximizes the fat / oil decomposition efficiency based on the detected dissolved oxygen concentration value. In this case, the flow rate of the water circulating through the circulation path C may be controlled so that the detected value of the dissolved oxygen concentration system is maintained within a predetermined range. In this case, a device capable of controlling the flow rate (e.g., a pump or a control valve) may be provided in the circulation path C. Note that, although control using the dissolved oxygen concentration as an index has been described here, this is merely an example, and the water treatment device 1 may be controlled based on any index as long as it is an index that can determine the status of fat / oil decomposition.

[0037] In this embodiment, fats and oils can be decomposed efficiently in the treatment tank 2, which has a relatively large capacity. Furthermore, because microorganisms are cultured in the culture tank 3, which has a relatively small capacity, it is easy to control the culture conditions (temperature, pH, etc.). Therefore, even when, for example, a sudden change occurs in the amount or properties of the organic wastewater flowing into the treatment tank 2, highly active microorganisms can be constantly supplied from the culture tank 3 to the treatment tank 2 via the circulation path C. Furthermore, the remaining fats and oils in the organic wastewater supplied from the treatment tank 2 to the culture tank 3 are easily decomposed by the highly active microorganisms, so the culture tank 3 can easily maintain an environment suitable for microbial growth. Additionally, because both the oxygen necessary for microbial activity in the treatment tank 2 and the oxygen necessary for microbial growth in the culture tank 3 are supplied by the ultrafine bubble supply device 6, there is no need to separately supply oxygen to the treatment tank 2 and the culture tank 3. This contributes to reducing the energy consumption of the water treatment device 1 as a whole.

[0038] When organic wastewater is treated as in this embodiment, the organic matter, nitrogen compounds, phosphorus compounds, minerals, and the like contained in the organic wastewater are utilized for the growth of microorganisms. Therefore, there is little need to use nutrients or the like to supplement these components. Therefore, the water treatment device 1 and water treatment method according to this embodiment are particularly suitable for treating organic wastewater containing oils and fats. If the water to be treated lacks nutrients, nutrients or the like may be added at any position in the circulation path C. In other words, the water treatment device according to the present invention may be provided with a means for adding nutrients. Furthermore, at least a portion of the raw water containing nutrients may be supplied to the culture tank within a range that does not adversely affect the growth of microorganisms in the culture tank.

[0039] The water to be treated in which the oils and fats have been decomposed flows out of the treatment tank 2 into the subsequent wastewater treatment facility. Since the oil and fat decomposition products can be treated relatively easily by known biological treatments or the like, the load on the wastewater treatment facility can be reduced by decomposing the oils and fats in the water treatment device 1 and then supplying the decomposed oils and fats to the wastewater treatment facility. In addition, the generation of sludge containing oils and fats (oil-containing sludge) can be suppressed.

[0040] Other Embodiments Finally, other embodiments of the water treatment device and water treatment method according to the present invention will be described. Note that the configurations disclosed in the following embodiments can be applied in combination with the configurations disclosed in other embodiments, as long as no contradiction occurs.

[0041] One aspect of the present invention can be implemented by modifying a conventional water treatment device. For example, the present invention can be implemented by converting a conventional water treatment device equipped with an adjustment tank (receiving tank) into a treatment tank of the present invention and modifying the device to newly include a culture tank, a first water supply channel, a second water supply channel, and an ultrafine bubble supply device. This aspect allows the use of an existing water treatment device and its site for implementing the water treatment device of the present invention, thereby reducing investment costs. In conventional water treatment devices, the amount of water delivered from the adjustment tank to downstream devices (e.g., a flotation device) varies depending on the treatment status of the downstream device. Because the water level in the adjustment tank generally fluctuates due to fluctuations in the water delivery rate, attempts to decompose fats and oils using microorganisms in the adjustment tank of conventional water treatment devices have been difficult due to significant environmental variables, including water level fluctuations, making it difficult to maintain an environment suitable for microbial growth, resulting in poor treatment results. Therefore, by repurposing the adjustment tank into the present invention, an environment suitable for microbial growth can be maintained, enabling effective fat and oil decomposition treatment.

[0042] In the above embodiment, a configuration in which the ultrafine bubble supplying device 6 supplies ultrafine bubbles to the culture tank 3 has been described as an example. However, in the present invention, the destination to which the ultrafine bubble supplying device supplies ultrafine bubbles may be at least one of the treatment tank, culture tank, first water supply channel, and second water supply channel. As described above, ultrafine bubbles have the property of remaining in water for a long time. Therefore, whether ultrafine bubbles are supplied to any of the above, oxygen necessary for microbial growth and fat decomposition can be distributed throughout the treatment tank, culture tank, first water supply channel, and second water supply channel. However, a configuration in which ultrafine bubbles are supplied to the culture tank as in the above embodiment is advantageous in that it facilitates microbial cultivation. Note that the ultrafine bubble supplying device may be provided in a configuration in which ultrafine bubbles are supplied to more than one of the treatment tank, culture tank, first water supply channel, and second water supply channel.

[0043] Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. [Industrial Applicability]

[0044] The present invention can be used for pretreatment of wastewater treatment in business establishments that discharge water containing oils and fats. [Explanation of symbols]

[0045] 1: Water treatment equipment 2: Treatment tank 3:Culture tank 31: Tank body 32: Stirring device 33: Drug supply device 34: Mixing blade 35: Motor 4:First water supply channel 5:Second water supply channel 51: Branch 52: Pump 6: Ultra-fine bubble supply device C: Circulation route

Claims

1. a treatment tank for receiving and storing water containing oil and fat; A culture tank for culturing microorganisms capable of decomposing fats and oils; A first water supply channel that sends water contained in the treatment tank to the culture tank; A second water supply channel that sends the water contained in the culture tank to the treatment tank; a water treatment device that supplies ultrafine bubbles to at least one of the treatment tank, the culture tank, the first water conveyance channel, and the second water conveyance channel.

2. The water treatment device according to claim 1 , wherein the ultrafine bubble supplying device supplies the ultrafine bubbles to at least the culture tank.

3. The water treatment device according to claim 1 , wherein the ultrafine bubble supply device includes a cavitation type bubble generation device.

4. The water treatment device according to any one of claims 1 to 3, wherein the culture tank has an agitator including a hyperboloid-shaped agitator blade.

5. Receiving and storing water containing oil and fat in a treatment tank; Culturing a microorganism capable of decomposing fats and oils in a culture tank; Sending the water containing the oil or fat from the treatment tank to the culture tank; Sending water containing the microorganisms from the culture tank to the treatment tank; and supplying ultrafine bubbles to at least one location in a water path including the treatment tank and the culture tank.

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