Water treatment system

Abstract

The present disclosure relates to a water treatment system comprising: a flotation cell; a shell and tube inflow part connected to the flotation cell and including a shell to supply gas and at least one tube to supply water to be treated, the shell and the tube having one end exposed to the outside of the flotation cell and the other end extending to the inside of the flotation cell, respectively; the microbubble forming device is positioned at the other end part of the shell or is arranged adjacent to the other end part of the shell; and the treated water discharge port is connected with the flotation tank and is used for discharging the treated water separated from the solid matters in the flotation tank.

Description

Technical Field

[0001] The present disclosure relates to a water treatment system. Background Art

[0002] Wastewater refers to water that contains liquid or solid water pollutants and cannot be used directly. Broadly speaking, wastewater includes domestic sewage, washing wastewater, industrial wastewater, agricultural and livestock wastewater, etc.

[0003] Wastewater treatment is a process of eliminating the adverse effects of wastewater on the rivers and oceans into which it flows by removing the pollutants contained in the wastewater or removing the harmfulness of the wastewater. Wastewater treatment methods include physical treatment methods such as screening, filtration, sedimentation, distillation, evaporation, and magnetic separation, as well as chemical treatment methods such as neutralization, oxidation-reduction, decomposition, flocculation, adsorption, flotation, extraction, ion exchange, stripping, and combustion / incineration. In addition, there are aerobic biological treatment methods such as activated sludge method, trickling filtration method, oxidation paper method, rotary disk method, and contact oxidation method, as well as anaerobic biological treatment methods such as digestion method (methane fermentation method) and septic tank.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] (Patent Document 1) KR10-2017-0136027A Summary of the Invention

[0007] (I) Technical Problem to be Solved

[0008] The present disclosure relates to a water treatment system.

[0009] (II) Technical Solution

[0010] One aspect of the present disclosure relates to a water treatment system, which includes: a flotation tank; a shell-and-tube inflow part connected to the flotation tank and including a shell for supplying gas and at least one tube for supplying water to be treated, the shell and the tube each having one end exposed to the outside of the flotation tank and the other end extending into the flotation tank; a microbubble forming device located at the other end of the shell or disposed adjacent to the other end of the shell; and a treated water discharge port connected to the flotation tank for discharging the treated water separated from solids in the flotation tank.

[0011] According to one embodiment, the flotation tank has a predetermined height, the shell-and-tube inflow part is connected to the lower part of the flotation tank, and the other ends of the shell and the tube each extend from the bottom of the flotation tank to a position equivalent to at least 25% of the height.

[0012] According to one embodiment, the shell-and-tube inflow part has one tube.

[0013] According to one embodiment, the shell-tube inflow part further includes a support part which is installed between the shell and the tube to maintain a separated distance therebetween.

[0014] According to one embodiment, the ratio of the diameter of the other end of the tube to the diameter of the other end of the shell is 1:1.1 to 1:3.

[0015] According to one embodiment, the ratio of the inflow speed of the water to be treated to the inflow speed of the gas is 1:1 to 6:1.

[0016] According to one embodiment, the size of the microbubbles formed by the microbubble forming device is 100 μm or less.

[0017] According to one embodiment, the microbubble forming device includes a membrane diffuser, an electroflotation device, a shear flotation device, a pressure flotation device, or a combination thereof.

[0018] According to one embodiment, the treated water discharge port is formed in the flotation tank at a position lower than the other end of the shell, the other end of the tube, or the microbubble forming device.

[0019] According to one embodiment, the discharge speed of the treated water discharged through the treated water discharge port is less than or equal to the inflow speed of the water to be treated flowing through the tube.

[0020] According to one embodiment, the water treatment system further includes a suspended solid recovery device.

[0021] (III) Advantageous Effects

[0022] According to one embodiment, bubbles with a long lifespan and a slow rising speed can be formed. According to one embodiment, the generation of turbulence caused by the bubbles can be suppressed. According to one embodiment, the adsorption rate between the particles and the bubbles can be increased. According to one embodiment, the floating efficiency of the particles in the water system can be improved. Description of the Drawings

[0023] Figure 1 is a schematic diagram of a water treatment system according to one embodiment.

[0024] Figure 2 is a schematic diagram of a water treatment system according to another embodiment.

[0025] Description of the Reference Numerals:

[0026] G: Gas

[0027] UW: Water to be treated

[0028] 100, 200: Water treatment system

[0029] 105: Shell tube inlet part

[0030] 108: Internal space

[0031] 110, 210: Flotation cell

[0032] 120: Shell

[0033] 121: One end part

[0034] 122: The other end part

[0035] 122e: The other end

[0036] 128: Bottom surface

[0037] 129: Inlet opening

[0038] 130: Tube

[0039] 131: One end part

[0040] 131e: One end

[0041] 132: The other end part

[0042] 132e: The other end

[0043] 140: Microbubble forming device

[0044] 149: Gas inlet

[0045] 150: Treated water outlet

[0046] 260: Overflow chamber

[0047] 270: Suspended solid outlet Detailed implementation manners

[0048] The present disclosure will be described in detail below with reference to the accompanying drawings. However, this is only exemplary, and the present disclosure is not limited to the specific implementation manners described exemplarily.

[0049] One aspect of the present disclosure provides a water treatment system. Untreated water such as wastewater flows into the water treatment system. The untreated water can be separated into solids and treated water in a flotation cell, and the solids and treated water can be recovered separately.

[0050] In the present disclosure, "water to be treated" is water in which solids and water are mixed, and there is no particular limitation as long as the solids can float in the flotation tank to separate the solids from the water. As an example, the water to be treated may be wastewater, which may include domestic wastewater, washing wastewater, industrial wastewater, agricultural and livestock wastewater, or a combination thereof as described above. Additionally, in the present disclosure, "treated water" refers to water from which solids have been separated from the water to be treated by the water treatment system provided in the present disclosure.

[0051] In the present disclosure, "solids" refers to impurities that must be removed from water in order to discharge the purified wastewater into rivers or the ocean. In the present disclosure, "solids" may be used interchangeably with expressions such as "impurities", "pollutants", "insoluble particles", and "suspended particles".

[0052] In the present disclosure, the term "microbubble forming device" refers to a device or equipment capable of generating bubbles of a gas supplied to the flotation tank. When the treated water fills the flotation tank, the microbubble forming device forms bubbles within an appropriate range of small sizes (usually in terms of diameter), specifically, bubbles within a range of about 0.1 mm (about 100 μm) or less.

[0053] In the present disclosure, when the microbubble forming device is disposed adjacent to the other end of the shell, the term "adjacent" may be defined as a position where the shortest distance between the microbubble forming device and the other end of the shell is less than the shortest distance between the microbubble forming device and the other end of the tube.

[0054] In the present disclosure, the terms "lower part", "upper part", and "upward" basically refer to the length direction of the system with respect to the fluid flow, regardless of whether the system with a specific length direction is arranged upward / vertically or horizontally or in other directions.

[0055] Figure 1 A schematic diagram showing a water treatment system 100 according to an embodiment of the present disclosure. The water treatment system includes: a flotation tank 110; a shell and tube inlet portion 105 including a shell 120 and at least one tube 130; a microbubble forming device 140; and a treated water discharge port 150.

[0056] The flotation tank has a predetermined internal space. As described later, the internal space may be filled with untreated water (UW) and gas G supplied into the flotation tank. The gas G may sequentially pass through the gas inlet 149, the shell, and the microbubble forming device and be supplied into the interior of the flotation tank. In the flotation tank, the solids present in the untreated water may float upward, thereby separating from the treated water (TW).

[0057] In the present invention, the "shell-and-tube inlet part" refers to the inlet part where the water to be treated and the gas flow into the flotation cell independently of each other, one end of which is exposed to the outside and the other end extends into the interior of the flotation cell. The shell-and-tube inlet part includes a shell and at least one tube, and the shell and the tube have the form of a general shell-and-tube device. Specifically, the shell is formed to surround the tube. In some embodiments where the shell-and-tube inlet part has one tube, the shell-and-tube inlet part can be interpreted as having a double-tube form including the tube as the inner tube and the shell as the outer tube.

[0058] The shell and the tube of such a shell-and-tube inlet part have independent flow paths from each other. Specifically, in the present disclosure, the gas flows through the shell. More specifically, the gas can flow through the gap between the outer surface of the tube and the inner surface of the shell. On the other hand, the water to be treated flows through the tube. More specifically, the water to be treated can flow through the hollow space inside the inner tube of the tube.

[0059] The shell-and-tube inlet part is connected to the flotation cell. In the present disclosure, the water treatment system can be a bottom-up water treatment system. The shell-and-tube inlet part can be arranged upward and can pass through the inlet opening 129 of the flotation cell. The shell can be firmly connected to the periphery of the inlet opening 129.

[0060] In the system, the gas and the water to be treated are supplied to the lower part of the flotation cell and can flow upward. Specifically, the shell-and-tube inlet part can be connected to the lower end part of the flotation cell. Here, the lower end part can be the lower side surface or the bottom surface 128 of the flotation cell. The flotation cell of the present disclosure can have a predetermined height. In the present disclosure, the "lower end part" and "lower part" of the flotation cell refer to below 50%, specifically below 40%, more specifically below 30%, further specifically below 25%, and further more specifically below 20% of the height of the flotation cell from the bottom. In addition, the "connection" means that the outer surface of the shell contacts the outer surface and the inner surface of the flotation cell in the thickness direction of the flotation cell.

[0061] Refer again to Figure 1 , the shell has one end part (first part) 121 exposed to the outside of the flotation cell and the other end part (second part) 122 extending into the interior of the flotation cell. The gas can be supplied from the outside through the one end part exposed to the outside. According to one embodiment, one end part of the shell can include a gas inlet through which the gas flows in from the outside.

[0062] The shell can pass through the outer surface and the inner surface of the flotation tank and extend into the internal space 108 of the flotation tank. In some embodiments, the other end of the shell can extend from the bottom of the flotation tank to a position equivalent to 20% to 50% of the height of the flotation tank. Specifically, it can extend to 20% to 40%, more specifically 25% to 25%, and most specifically 30%. In order to separate the treated water from the continuously flowing water to be treated and recover it from the flotation tank during the actual operation of the water treatment system, the treated water can be recovered from the flotation tank through a treated water discharge port 150 provided at a position lower than the other end 122e of the shell.

[0063] As the gas supplied to the inside of the flotation tank through the shell of the present disclosure, as will be described later, a gas that can easily generate microbubbles in the flotation tank and is not easily dissolved in the wastewater can be used. By way of example, the gas can include air, oxygen, nitrogen, or a combination thereof.

[0064] In addition, referring to Figure 1 , the tube also has one end 131 exposed to the outside of the flotation tank and the other end 132 extending into the inside of the flotation tank. One end 131e of the tube can be exposed to the outside of the flotation tank and can not be surrounded by the shell. The other end 132e of the tube can be exposed to the inside of the flotation tank and can not be surrounded by the shell. The water to be treated can be supplied from the outside through one end 131e of the tube exposed to the outside. According to one embodiment, one end of the tube can include an inlet for the water to be treated flowing in from the outside.

[0065] The tube can also pass through the outer surface and the inner surface of the flotation tank and extend into the internal space of the flotation tank. In some embodiments, the other end of the tube can extend from the bottom of the flotation tank to a position equivalent to at least 20% to 50% of the height of the flotation tank. Specifically, it can extend to 20% to 40%, more specifically 25% to 35%, and most specifically 30%. In order to separate the treated water from the continuously flowing water to be treated and recover it from the flotation tank during the actual operation of the water treatment system, the treated water can be recovered from the flotation tank through a treated water discharge port 150 provided at a position lower than the other end of the tube.

[0066] In addition, the solids in the water to be treated flowing through the tube can float upward by the bubbles originating from the gas flowing through the shell. From the aspect of the floating efficiency of these solids, the position of the other end 132e of the tube can be higher than the position of the other end 122e of the shell.

[0067] The shell-and-tube inflow part of the present disclosure may include at least one tube. In one embodiment, the shell-and-tube inflow part may include at least two tubes. The multiple tubes are spaced apart from each other and disposed within the shell. Using multiple tubes can increase the dispersion of the water to be treated flowing into the flotation tank, which helps the solids float more quickly.

[0068] In another embodiment, the shell-and-tube inflow part may have one tube. Specifically, the shell-and-tube inflow part may have one tube and one shell with concentric cross-sections with respect to each other. When one tube is used, the gas can be relatively more concentrated around the other end of the tube, making it easier for microbubbles originating from the gas to form a so-called microbubble curtain. Therefore, using one tube helps improve the purity of the treated water.

[0069] In one embodiment where the shell-and-tube inflow part has one tube, the ratio of the diameter of the other end of the tube to the diameter of the other end of the shell may be from 1:1.1 to 1:3. Specifically, the ratio may be from 1:1.2 to 1:2.8, and more specifically, may be from 1:1.2 to 1:2. If the ratio is less than the above range, the floating effect of the microbubbles may be reduced, and the purity of the treated water may be reduced. If the ratio exceeds the above range, the economy may be reduced.

[0070] Correspondingly, the difference in the supply rates of the gas and the water to be treated may also affect the performance of the water treatment system. According to one embodiment, the ratio of the inflow rate of the water to be treated to the inflow rate of the gas may be from 1:1 to 6:1, specifically, the ratio may be from 1.5:1 to 3:1. If the ratio is less than the above range, the floating effect of the microbubbles may be reduced, and the purity of the treated water may be reduced. If the ratio exceeds the above range, the economy may be reduced.

[0071] As described above, the shell and the tube respectively provide independent flow paths for the gas and the water to be treated. For this purpose, a certain separation distance may be maintained between the shell and the tube. According to one embodiment, the shell-and-tube inflow part may further include a support part, which is installed between the shell and the tube to maintain the separation distance between the shell and the tube.

[0072] The inflow part with such a structure used in the water treatment system of the present disclosure increases the gas distribution around the water to be treated flowing into the flotation tank, thereby promoting the floating of the solids in the water to be treated regardless of the length and width of the flotation tank.

[0073] The water treatment system of the present disclosure includes a microbubble forming device. As Figure 1As shown, the microbubble forming device is located at the other end of the shell or adjacent to the other end of the shell. Gas is discharged from the other end of the shell into the internal space of the flotation tank, and microbubbles are formed through the microbubble forming device. The microbubbles thus formed can form an air curtain at the bottom of the water to be treated discharged from the other end 132e of the pipe into the internal space of the flotation tank. The air curtain can prevent solids in the water to be treated from precipitating and can promote the floating of the solids.

[0074] According to an embodiment of the present disclosure, the size of the microbubbles formed by the microbubble forming device can be 100 μm or less. Specifically, the size of the microbubbles can be 1 - 100 μm, for example, 1 - 50 μm, more specifically 5 - 100 μm, for example, 5 - 50 μm, further specifically 10 - 100 μm, for example, 10 - 40 μm, further more specifically 20 - 100 μm, for example, 20 - 40 μm. For example, the size of the microbubbles can be measured by a transient wet bubble / particle size analysis system. The analysis system can image the contaminant particles and / or bubbles present in the liquid through the synchronization of a high-speed camera and a nanosecond pulsed laser, and analyze the size distribution and shape of the particles and / or bubbles. When the size of the microbubbles is 100 μm or less, compared with when the size of the microbubbles exceeds 100 μm, the solids can float and slowly rise to the liquid surface in the flotation tank. In addition, it has a relatively long bubble lifetime of about 1 to 2 minutes and a large surface area, so it is advantageous in terms of the floating efficiency of the solids. If the size of the bubbles exceeds the above range, the rising speed of the bubbles will be too fast, and turbulence may be generated during the rising process, resulting in a reduction in the floating efficiency of the solids. On the contrary, if the size of the bubbles is less than the above range, the rising speed of the bubbles is too slow and the bubbles stay in the water, which may lead to a reduction in the floating efficiency of the solids.

[0075] In the present disclosure, the microbubble forming device is not particularly limited as long as it can be adjacent to the other end of the shell and can form microbubbles having the above size. According to an embodiment, the microbubble forming device can include a membrane diffuser, an electro flotation device, a shear flotation (SF) device, a pressurized flotation device, or a combination thereof. Specifically, the membrane diffuser can include an air flotation (AF) ceramic membrane. In addition, the shear flotation device can include an SF-internal circulation type device. In addition, the pressurized flotation device can include a dissolved air flotation (DAF) pressurized tank type device and a DAF-pressurized pump type device.

[0076] The water treatment system of the present disclosure includes a treated water discharge outlet. The treated water discharge outlet can be connected to a flotation cell and discharge the treated water separated from solids in the flotation cell to the outside. In order to separate the treated water from the continuously flowing water to be treated and recover it from the flotation cell during the actual operation of the water treatment system, the treated water discharge outlet can be formed at a position lower than the other end of the shell, the other end of the pipe, or the microbubble forming device. More specifically, the treated water discharge outlet can be connected to the flotation cell at a position lower than the other end of the shell, the other end of the pipe, and the microbubble forming device.

[0077] The discharge rate of the treated water discharged through the treated water discharge outlet can be adjusted according to the inflow rate of the incoming water to be treated. According to one embodiment, the discharge rate of the treated water discharged through the treated water discharge outlet can be less than or equal to the inflow rate of the incoming water to be treated flowing through the pipe. A faster discharge rate of the treated water than the inflow rate of the incoming water to be treated may result in a decrease in the purity of the treated water.

[0078] Solids floating up to the liquid surface in the flotation cell together with the microbubbles can be recovered. According to one embodiment, the water treatment system can further include a suspended solids recovery device. In the present disclosure, the suspended solids recovery device is not particularly limited. As an example, the suspended solids recovery device can include a skimmer.

[0079] Figure 2 is a schematic diagram showing a water treatment system 200 according to another embodiment of the present disclosure. As another example, as Figure 2 shown, the suspended solids recovery device can include an overflow chamber 260. The contaminated solids that are lifted to the water surface by the microbubbles overflow from the flotation cell 210 through the continuous supply of untreated water. The overflowed solids are collected in the overflow chamber. In one embodiment, the diameter of the overflow chamber can be 2-4 times the diameter of the flotation cell. Additionally, the height of the overflow chamber can be 1 / 5 to 1 / 2 times the height of the flotation cell.

[0080] According to another embodiment, the flotation cell can include a suspended solids discharge outlet. The suspended solids discharge outlet can be located at the upper end of the flotation cell. More specifically, the suspended solids discharge outlet can be formed at a position higher than the other end of the shell, the other end of the pipe, and / or the microbubble forming device.

[0081] As Figure 2 shown, the suspended solids recovery device can further include a suspended solids discharge outlet 270. The solids S collected in the overflow chamber 260 can be discharged to the outside through the suspended solids discharge outlet 270.

[0082] Compared with traditional water treatment systems, the water treatment system of the present disclosure described above has a simple structure, so it can be miniaturized and can provide easier wastewater treatment.

[0083] The above are only examples of applying the principles of the present disclosure, and other configurations may also be included without departing from the scope of the present invention.

Claims

1. A water treatment system, comprising: A flotation tank; A shell-and-tube inlet section connected to the flotation tank and including a shell for supplying gas and at least one tube for supplying water to be treated, the shell and the tube each having one end exposed to the outside of the flotation tank and the other end extending into the flotation tank; A microbubble forming device located at or adjacent to the other end of the shell; And A treated water discharge port connected to the flotation tank for discharging the treated water separated from solids in the flotation tank.

2. The water treatment system according to claim 1, wherein The flotation tank has a predetermined height, The shell-and-tube inlet section is connected to the lower part of the flotation tank, The other ends of the shell and the tube extend from the bottom of the flotation tank to a position equivalent to at least 25% of the height.

3. The water treatment system according to claim 1, wherein The shell-and-tube inlet section has one tube.

4. The water treatment system according to claim 1, wherein The shell-and-tube inlet section further includes a support section installed between the shell and the tube to maintain a separation distance therebetween.

5. The water treatment system according to claim 1, wherein The ratio of the diameter of the other end of the tube to the diameter of the other end of the shell is 1:1.1 to 1:

3.

6. The water treatment system according to claim 1, wherein The ratio of the inflow rate of the water to be treated to the inflow rate of the gas is 1:1 to 6:

1.

7. The water treatment system according to claim 1, wherein The size of the microbubbles formed by the microbubble forming device is 100 μm or less.

8. The water treatment system according to claim 1, wherein The microbubble forming device includes a membrane diffuser, an electroflotation device, a shear flotation device, a pressure flotation device, or a combination thereof.

9. The water treatment system according to claim 1, wherein The treated water discharge port is formed in the flotation tank at a position lower than the other end of the shell, the other end of the tube, or the microbubble forming device.

10. The water treatment system according to claim 1, wherein The discharge rate of the treated water discharged through the treated water discharge port is less than or equal to the inflow rate of the water to be treated flowing through the tube.

11. The water treatment system according to claim 1, wherein The water treatment system further includes a suspended solid recovery device.

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