Energy-Saving Advanced Wastewater Treatment System Using Microbubble and Submerged Membrane

Abstract

The present invention relates to an advanced wastewater treatment system comprising: an anoxic tank (110) for removing nitrogen in incoming wastewater; an aerobic tank (120) in which organic matter oxidation and nitrification are performed in the treated water flowing in from the anoxic tank (110), and phosphorus removal microorganisms absorb excess phosphorus; a membrane separation tank (140) for removing solid matter from the treated water passing through the aerobic tank (120) using an internally provided immersion membrane (141) and returning a portion of the separated sludge to the anoxic tank (110); and a chemical coagulation tank (150) for removing phosphorus (P) by adding a coagulant to the treated water flowing in from the membrane separation tank (140). It is characterized by including a pressurized flotation tank (160) that releases air in the form of bubbles into the treated water passing through the chemical coagulation tank (150), causing the coagulated suspended matter inside the treated water to rise due to the buoyancy of the bubbles, and then removes it and discharges the final treated water.

Description

Technology Field

[0001] The present invention relates to an advanced wastewater treatment system, and more specifically, to an energy-saving advanced wastewater treatment system capable of reducing the energy required for operation and improving water treatment efficiency. Background Technology

[0002] With recent industrial development and improvements in living standards, water quality in discharge areas has worsened, public awareness of environmental pollution has increased, and permissible discharge standards for treated water quality have been strengthened. Consequently, the secondary treatment processes of the past are no longer effective in improving the water quality of discharge areas, and the need for recycling treated water is emerging due to water resource shortages, leading to a growing need for advanced treatment.

[0003] Currently, wastewater treatment processes employ a biological process using activated sludge to reduce the concentration of organic matter in wastewater by allowing aerobic microorganisms to oxidize and acquire organic matter under aerobic conditions.

[0004] Conventional water treatment systems designed for the advanced biological treatment of organic matter, nitrogen, and phosphorus utilize methods such as A2 / O, Bardenpho, and SBR, as well as variations thereof. These methods involve repeatedly arranging aerobic tanks, byproduct tanks, and anaerobic tanks to remove organic matter, nitrogen, and phosphorus, and biologically removing pollutants using internal circulation.

[0005] FIG. 1 (a) is a schematic diagram illustrating an A2 / O treatment method (10) used in a conventional water treatment system, and FIG. 1 (b) is a schematic diagram illustrating a Bardenpho treatment method (20).

[0006] In the A2 / O treatment method (10), wastewater (W) passes through an anaerobic tank (11), an anoxic tank (13), an aerobic tank (15), and a secondary sedimentation tank (17) in sequence before being discharged. Wastewater (W) flows into the anaerobic tank (11), where phosphorus-removing microorganisms become active, and the treated water (W1) moves to the anoxic tank (13) to remove nitrogen. Then, nitrification and organic matter oxidation take place in the aerobic tank (15). The sludge (S) settled in the secondary sedimentation tank (17) is partially returned and recirculated to the anoxic tank (13), and the final treated water (W2) is discharged. The A2 / O treatment method (10) can remove nitrogen and phosphorus simultaneously through a relatively simple process.

[0007] In the Bardenpho treatment method (20), wastewater (W) passes through an anaerobic tank (21), a first-stage anoxic tank (22), a first-stage aerobic tank (23), a second-stage anoxic tank (24), a second-stage aerobic tank (25), and a second sedimentation tank (26) in sequence before being discharged. The wastewater (W) enters the anaerobic tank (21) to perform phosphorus removal, nitrates are removed by denitrification in the first-stage anoxic tank (22), and ammonia is converted into nitrates in the first-stage aerobic tank (23). Then, residual nitrates are additionally denitrified in the second-stage anoxic tank (24), and the wastewater is finally treated in the second-stage aerobic tank (25) before discharge. The Bardenpho treatment method (20) is a process specialized for nitrogen removal and exhibits high nitrogen removal efficiency through an additional denitrification step.

[0008] This biological technology for the simultaneous removal of organic matter, nitrogen, and phosphorus has limitations, such as the difficulty of properly maintaining each reactor and the excessive maintenance costs associated with internal recirculation and methanol injection.

[0009] Meanwhile, as the issue of algal blooms and eutrophication in rivers has recently emerged, the demand for the removal of phosphorus (P) from treated water quality has increased. Consequently, chemical treatment facilities are being added to the downstream end of water treatment systems to remove phosphorus. Since phosphorus is easily removed by reacting with coagulants such as PAC, Alum, and iron salts, it is being removed by sedimentation, filtration, or pressurized flotation after coagulation.

[0010] FIG. 2 is a schematic diagram illustrating an example of a water treatment system (30) with a chemical treatment facility for phosphorus removal added to the rear end.

[0011] In the water treatment system (30), wastewater (W) passes through an anoxic tank (31), an aerobic tank (32), a first-stage sedimentation tank (33), a chemical coagulation tank (34), and a second-stage sedimentation tank (35) in sequence before being discharged. Phosphorus (P) is removed after coagulation in the chemical coagulation tank.

[0012] Following these changes in approach, biological processes are simplified to focus solely on the removal of organic matter and nitrogen, while processes that remove phosphorus through chemical treatment at the downstream stage are commonly used.

[0013] However, the conventional water treatment systems (10, 20, 30) illustrated in FIGS. 1 and 2 have limitations in that it is difficult to maintain the appropriate efficiency of each reaction tank, and the treatment efficiency varies depending on the load fluctuation of the incoming pollutants.

[0014] In addition, there is a disadvantage of high energy costs due to excessive internal recirculation requirements. Furthermore, there is a problem with the device size increasing in order to process nitrification in the aerobic tank. The problem to be solved

[0016] The objective of the present invention is to solve the aforementioned problems and to provide an advanced wastewater treatment system capable of reducing energy costs required for maintenance, maintaining constant treatment efficiency even with fluctuations in the load of incoming pollutants, and enabling stable nitrification in the aerobic tank.

[0017] The above-mentioned objectives and various advantages of the present invention will become more apparent to those skilled in the art from the preferred embodiments of the present invention. means of solving the problem

[0019] The objective of the present invention can be achieved by an energy-saving advanced wastewater treatment system. The advanced wastewater treatment system of the present invention comprises: an anaerobic tank (110) for removing nitrogen in the incoming wastewater; an aerobic tank (120) in which organic matter oxidation and nitrification are performed in the treated water flowing in from the anaerobic tank (110), and phosphorus-removing microorganisms absorb excess phosphorus; a membrane separation tank (140) for removing solid matter from the treated water passing through the aerobic tank (120) using an internally provided immersion membrane (141) and returning a portion of the separated sludge to the anaerobic tank (110); and a chemical coagulation tank (150) for removing phosphorus (P) by adding a coagulant to the treated water flowing in from the membrane separation tank (140). It is characterized by including a pressurized flotation tank (160) that releases air in the form of bubbles into the treated water passing through the chemical coagulation tank (150), causing the coagulated suspended matter inside the treated water to rise due to the buoyancy of the bubbles, and then removes it and discharges the final treated water.

[0020] According to one embodiment, the aeration tank (120) delivers oxygen by microbubbles generated by a microbubble generator (130), and the microbubble generator (130) comprises: a body (131) in which the internal space is divided into an upper space (131d) and a lower space (131b) by a separator (131a); a treated water inlet pipe (133) for supplying treated water (W1) to the upper space; and an air inlet pipe (135) for supplying air to the central area of ​​the lower space (131b) which is provided to penetrate the upper space downwardly. It includes a plurality of spray nozzles (131e) that are coupled to the above-mentioned isolation plate (131a) and spray the treated water flowing into the upper space (131d) into the lower space (131b). In the lower space (131b), a funnel-shaped inclined surface (131c) is provided on the spray path of the spray nozzle (131e), the inner diameter of which gradually narrows as it goes downward. The spray nozzle (131e) is coupled to spray the treated water in an obliquely inclined direction along the circumferential direction of the inclined surface (131c), and the treated water sprayed from the spray nozzle (131e) flows spirally along the inclined surface (131c).

[0021] According to one embodiment, the pressurized flotation tank (160) comprises: a flotation tank body (161) into which treated water from the chemical coagulation tank (150) flows; a floating material storage tank (165) provided opposite to the treated water inflow area of ​​the flotation tank body (161) to collect coagulated floating material; a bubble dissolving unit (169) for dissolving bubbles in the treated water discharged from the flotation tank body (161); and a plurality of first bubble generating nozzles (166a) provided below the treated water inflow area of ​​the flotation tank body (161) to spray circulating water containing bubbles supplied from the bubble dissolving unit (169) into the flotation tank body (161). It may include a plurality of second bubble generating nozzles (166b) that are spaced apart from the first bubble generating nozzle (166a) inside the flotation tank body (161) and generate bubbles larger than the size of the bubbles generated by the first bubble generating nozzle (166a); a third bubble generating nozzle (166c) that is provided below the treated water discharge area of ​​the flotation tank body (161) and generates bubbles larger than the size of the bubbles generated by the second bubble generating nozzle (166b); and a plurality of air injection nozzles (167) that are provided at regular intervals along the longitudinal direction on the upper inner wall surface of the flotation tank body (161) and inject air into aggregated floating matter that has risen to the water surface to move the aggregated floating matter to the floating matter storage tank (165). Effects of the invention

[0023] The wastewater advanced treatment system according to the present invention uses a microbubble generator instead of a blower used in conventional aerobic tanks, so the energy cost of the aerobic tank can be reduced by more than 30%.

[0024] In addition, 200 to 400 percent of the inflow rate is internally recirculated from the aerobic tank to the anoxic tank for nitrogen removal. In the present invention, since internal circulation is achieved by gravity flow without a separate pump using a microbubble generator, an internal recirculation pump is not required, and thus energy costs for internal circulation can be reduced by 100%.

[0025] In addition, by applying a high-efficiency pressurized flotation tank, the operating pressure is significantly reduced from the conventional 5 atmospheres or more to 3 atmospheres or less, allowing for a reduction of more than 40% in energy required for phosphorus removal.

[0026] In addition, maximizing the oxygen transfer rate through a microbubble generator enables the removal of organic matter and stable nitrification, and increasing the nitrogen removal rate through appropriate automatic circulation. Brief explanation of the drawing

[0028] FIGS. 1 and FIGS. 2 are schematic diagrams illustrating the water treatment process of a conventional water treatment system. FIG. 3 is a schematic diagram schematically illustrating the configuration of a wastewater advanced treatment system according to the present invention. FIG. 4 is a schematic plan view illustrating the direction of movement of treated water in the anoxic tank, aerobic tank, and membrane separation tank of the wastewater advanced treatment system according to the present invention. FIG. 5 is a perspective view illustrating the configuration of a microbubble generator of a wastewater advanced treatment system according to the present invention. FIG. 6 is a cross-sectional view illustrating the cross-sectional configuration of a microbubble generator. FIG. 7 is an exemplary diagram illustrating the direction of movement of treated water through the spray nozzle of a microbubble generator. FIG. 8 is an exemplary side cross-sectional view schematically illustrating the configuration of a pressurized flotation tank of a wastewater advanced treatment system according to the present invention. FIG. 9 is a plan cross-sectional example schematically illustrating the configuration of a pressurized flotation tank. Specific details for implementing the invention

[0029] To fully understand the present invention, preferred embodiments of the invention are described with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described in detail below. These embodiments are provided to more completely explain the present invention to those with average knowledge in the art. Accordingly, the shapes of elements in the drawings may be exaggerated to emphasize clearer explanations. It should be noted that in each drawing, identical components may be depicted with the same reference numeral. Detailed descriptions of known functions and configurations that are deemed to unnecessarily obscure the essence of the present invention are omitted.

[0031] FIG. 3 is a schematic diagram showing the overall configuration of a wastewater advanced treatment system (100) according to the present invention.

[0032] As described above, the wastewater advanced treatment system (100) according to the present invention comprises: an anoxic tank (110) for removing nitrogen in the incoming wastewater; an aerobic tank (120) in which organic matter oxidation and nitrification are performed in the treated water (W1) flowing in from the anoxic tank (110) and phosphorus removal microorganisms absorb excess phosphorus; a microbubble generating device (130) for mixing microbubbles with the circulating water supplied from the anoxic tank (110) and supplying it to the aerobic tank (120); a membrane separation tank (140) for removing solid matter using an internally provided immersion membrane (141) of the treated water passing through the aerobic tank (120) and returning a portion of the separated sludge (S) to the anoxic tank (110); and a chemical coagulation tank (150) for removing fine suspended matter and phosphorus (P) by coagulating it by adding a coagulant to the treated water (W1) flowing in from the membrane separation tank (140). It includes a pressurized flotation tank (160) that releases air in the form of microbubbles into the treated water (W1) that has passed through the chemical coagulation tank (150), causing the coagulated suspended matter inside the treated water to rise due to the buoyancy of the bubbles and then removes it, and discharges the final treated water (W2).

[0033] The wastewater advanced treatment system (100) according to the present invention employs a membrane separation tank (140) instead of the secondary sedimentation tank (17) of the conventional A2 / O method (10) shown in FIG. 1 (a), and arranges a chemical coagulation tank (150) and a pressurized flotation tank (160) at the rear end of the membrane separation tank (140) to improve the treatment efficiency of phosphorus (P).

[0034] In addition, the wastewater advanced treatment system (100) according to the present invention adopts a structure in which oxygen from the atmosphere is automatically drawn in and generated and supplied as microbubbles by using a circulating water pump (116) to circulate the treated water (W1) through a microbubble generating device (130) without using the conventional aeration method through a blower or aeration device of the aerobic tank (120). By doing so, it is possible to generate very small bubbles compared to conventional blowers, thereby maximizing oxygen transfer efficiency and improving energy efficiency.

[0036] FIG. 4 is a planar example illustrating the process of moving treated water between an anaerobic tank (110), an aerobic tank (120), and a membrane separation tank (140).

[0037] The anaerobic tank (110) removes nitrogen from the incoming wastewater (W). The anaerobic tank (110) is provided in the form of a tank and is equipped with an agitator (113) inside to remove organic matter and nitrate (NO3 - Increases contact with ). On one side of the anoxic tank (110), a wastewater inlet pipe (111) into which wastewater (W) flows is provided, and a circulating water supply pipe (115) that circulates and supplies treated water (W1) inside the anoxic tank (110) to the aerobic tank (120) is arranged to connect the anoxic tank (110) and the aerobic tank (120). A circulating water pump (116) is connected to the circulating water supply pipe (115). On the other side of the anoxic tank (110), a sludge return pipe (117) that receives sludge (S) from the membrane separation tank (140) is connected.

[0038] The anaerobic tank (110) is nitrate (NO3) produced in the aerobic tank (120). -When ) is returned and introduced, the organic matter is used as an electron source to reduce the nitrate to nitrogen gas (N₂). The reduced nitrogen gas is released into the atmosphere and removed.

[0039] The anaerobic tank (110) maintains the internal microbial concentration through sludge (S) returned from the membrane separation tank (140). It is mixed using a stirrer (113) to increase the efficiency of organic matter decomposition and denitrification.

[0041] The aerobic tank (120) performs nitrification, improves oxygen transfer efficiency, and circulates nitrates. The aerobic tank (120) receives treated water (W1) mixed with microbubbles from the anoxic tank (110) via a microbubble generator (130).

[0042] The aerobic tank (120) is ammonia (NH4 + ) nitrate (NO3 - It converts into ) and allows microorganisms (nitrifying bacteria) to use oxygen to decompose ammonia.

[0043] Here, in the present invention, oxygen supply to the aerobic tank (120) is achieved using a microbubble generator (130). The microbubble generator (130) generates microbubbles through physical vortices instead of a blower, thereby maximizing oxygen transfer efficiency and reducing energy consumption.

[0044] FIG. 5 is a perspective view illustrating the configuration of a microbubble generating device (130), FIG. 6 (a) is a side cross-sectional view illustrating the side cross-sectional configuration of the microbubble generating device (130), FIG. 6 (b) is a cross-sectional view illustrating the cross-sectional configuration along line AA of FIG. 6 (a), FIG. 7 (a) is a perspective view illustrating the arrangement structure of a spray nozzle (131e), FIG. 7 (b) is a cross-sectional view illustrating the cross-sectional configuration along line BB of FIG. 6 (a), and FIG. 7 (c) is an example diagram illustrating the mixing direction of the treated water (W1) and air (A).

[0045] The microbubble generating device (130) of the present invention micronizes air (A) supplied from the outside and mixes it with treated water (W1) supplied from the anaerobic tank (110) and supplies it to the aerobic tank (120). The microbubble generating device (130) comprises a body (131) in which the internal space is divided into an upper space (131d) and a lower space (131b) by a separator (131a), a treated water inlet pipe (133) for supplying treated water (W1) to the upper space (131d), an air inlet pipe (135) provided to penetrate downward through the upper space (131d) for supplying air (A) to the central area of ​​the lower space (131b), and a plurality of spray nozzles (131e) coupled to the separator (131a) for spraying the treated water (W1) supplied to the upper space (131d) into the lower space (131b).

[0046] The treated water inlet pipe (133) is connected to the circulating water supply pipe (115) to supply treated water (W1) supplied from the anaerobic tank (110) to the upper space (131d). The treated water (W1) supplied to the upper space (131d) is sprayed into the lower space (131b) through a plurality of spray nozzles (131e) connected to the isolation plate (131a) as shown in FIG. 6 (a), and the air (A) supplied through the air inlet pipe (135) descends vertically into the lower space (131b).

[0047] The inner wall of the lower space (131b), which forms the path through which the treated water (W1) is sprayed from the spray nozzle (131e), is provided with a funnel-shaped inclined surface (131c) whose inner diameter gradually narrows toward the bottom. The treated water (W1) sprayed from the spray nozzle (131e) first strikes the inclined surface (131c) and then flows along the inclined surface (131c).

[0048] At this time, as shown in FIG. 7 (a), the plurality of spray nozzles (131e) are not connected perpendicularly to the isolation plate (131a) but are arranged at an angle along the circumferential direction of the isolation plate (131a) to spray the treated water (W1) at a certain angle.

[0049] When each spray nozzle (131e) is arranged to be inclinedly coupled to the isolation plate (131a), the treated water (W1) sprayed from each spray nozzle (131e) flows in a spiral along the inclined surface (131c) as shown in (b) of FIG. 7.

[0050] That is, the treated water (W1) sprayed from the spray nozzle (131e) moves downward in a spiral motion as shown by the solid arrow in Fig. 7 (c), and the air (A) sprayed from the air inlet pipe (135) is discharged by penetrating vertically through the central region of the spiral flow path of the treated water (W1) as shown by the dotted line. At this time, as the flow velocity of the treated water (W1) sprayed from the spray nozzle (131e) increases while moving spirally along the inclined surface (131c), the air passing through the center of the flow path of the treated water (W1) is drawn into the treated water (W1) side by the pressure difference and is deformed into fine bubbles and mixed with the treated water (W1).

[0051] As the treated water (W1) flows spirally along the inclined surface (131c), a force is also formed to move upward toward the top of the inclined surface (131c) due to centrifugal force, so the wastewater (W) flows spirally along the inclined surface (131c) for a long time. When the treated water (W1) flows spirally for a long time in this way, the contact time between the treated water (W1) and the air (A) increases further, so the treated water discharged to the bottom of the mixing pipe (137) is in a state where a large amount of microbubbles are mixed in.

[0052] Meanwhile, if the treated water (W1) flowing spirally along the inclined surface (131c) falls into the aerobic tank (120) immediately after being discharged from the body (131), the flow velocity of the treated water (W1) decreases rapidly, and the effect of air changing into fine bubbles and mixing with the treated water (W1) is reduced. Furthermore, since the distance over which the spirally flowing treated water (W1) comes into contact only with the air sprayed from the spray nozzle (131e) is shortened, a limit is created in increasing the dissolved oxygen content of the treated water (W1).

[0053] Accordingly, the microbubble generating device (130) of the present invention is provided with a mixing pipe (137) at the outlet side of the lower space (131b) as shown in FIG. 5 so as to secure a long space where the treated water (W1) and microbubbles come into contact.

[0054] Meanwhile, as shown in FIG. 3, a guide tube (139) is connected to the lower part of the microbubble generator (130). The guide tube (139) extends from the mixing tube (137) to the bottom of the aerobic tank (120). The guide tube (139) causes the treated water (W1) mixed with microbubbles to be discharged to the bottom of the aerobic tank (120), thereby increasing the amount of dissolved oxygen in the bottom of the aerobic tank (120). Furthermore, as the microbubbles inside the treated water (W1) float toward the water surface and dissolve into the treated water inside the aerobic tank (120), the amount of dissolved oxygen increases throughout the entire treated water (W1) inside the aerobic tank (120).

[0055] By applying the microbubble generator (130) in this way, the oxygen transfer efficiency can be increased compared to when using a conventional blower, and the energy can be reduced by up to 30-50%.

[0057] Meanwhile, the treated water (W1) of the anoxic tank (110) is supplied to the aerobic tank (120) through the circulating water supply pipe (115) by the circulating water pump (116), and oxygen is transferred through the microbubble generator (130). In addition, as the circulating water is circulated in greater quantities than the inflow rate of wastewater (W) entering the anoxic tank (110), the excess water is automatically returned to the anoxic tank (110) by gravity flow.

[0058] That is, the inflow rate of wastewater (W) flowing into the anoxic tank (110) is 100m 3 / h, and the amount of circulating water supplied to the aerobic tank (120) by the circulating water pump (116) is 300m 3 When / h, the excess treated water is 200m 3 / h is physically overflowed after treatment in the aerobic tank (120). The overflowed treated water (W1) is transferred to the anoxic tank (110) as shown in FIG. 4.

[0059] Compared to the A2 / O method (10) shown in Fig. 1 (a), where a large pump is used to internally return 200 to 400% of the inflow rate of treated water from the aerobic tank (15) to the anoxic tank (13) for nitrogen removal, the present invention saves energy by not using a pump because the circulating water is returned by gravity.

[0061] The membrane separation tank (140) filters out sludge (S) through solid-liquid separation and transfers the treated water (W1) to the chemical coagulation tank (150). The membrane separation tank (140) can maintain a high concentration of microorganisms (MLSS) using an immersion-type immersion membrane (141).

[0062] In the present invention, a membrane separation tank (140) using an immersion type immersion membrane (141) is adopted instead of a sedimentation tank. While the microbial concentration in the aeration tank must be maintained at 2000~4000 ppm when using a conventional sedimentation tank, when using a membrane separation tank (140) as in the present invention, it is possible to maintain a high concentration of 8000~13000 ppm, thereby reducing the size of the reaction tank and providing the effect of strongly responding to fluctuations in the inflow load.

[0063] The sedimentation tank settles sludge by gravity, so if the MLSS is too high, the sludge does not settle well and mixes with the treated water in a suspended state. Accordingly, the sedimentation tank must maintain the MLSS at 2,000 to 4,000 ppm.

[0064] On the other hand, the membrane separation tank (140) separates sludge and water by physical filtration. Since there is no dependence on gravity, separation efficiency is maintained even when the sludge concentration is high. As a result, a much higher MLSS can be maintained within the reaction tank.

[0065] Therefore, by using a membrane separation tank (140) instead of a sedimentation tank, the size of the reaction tank can be reduced to lower installation costs, treatment efficiency can be increased to respond stably to fluctuations in inflow load, and maintenance costs can be reduced by removing the sedimentation tank.

[0066] Here, the immersion membrane (141) used in the membrane separation tank (140) may be of the flat plate type, hollow fiber type, etc., and it is preferable to use MF or UF with a pore size of 0.0001 to 0.4㎛ in the range of the immersion membrane (141).

[0067] A sludge discharge pipe (143) is connected to the membrane separation tank (140) to return a portion of the sludge (S) to the anoxic tank (110).

[0068] In the present invention, the RAS is set to 20~50% Q, so that the microbial concentration can be maintained even with a lower return flow rate compared to A2 / O and Bardenpho. Nitrified Recycle is designed to automatically circulate 200~400% Q through a microbubble generator, so no separate energy is consumed, thereby ensuring nitrogen removal efficiency while significantly reducing energy consumption compared to the Bardenpho method (400% Q).

[0069] In addition, the RAS flow rate is low, which reduces sludge pump energy, and the nitrification return rate is appropriately high, which has the effect of minimizing energy consumption while maintaining denitrification efficiency.

[0071] The chemical coagulation tank (150) is positioned downstream of the membrane separation tank (140) and removes phosphorus (P) from the water by adding a coagulant to the treated water flowing in from the membrane separation tank (140). The chemical coagulation tank (150) may use an aluminum-based coagulant, for example, aluminum sulfate (Al2(SO4)3). Aluminum sulfate (Al2(SO4)3) contains phosphorus (PO4 3- It reacts with ) to form aluminum phosphate (ALPO4).

[0072] In the chemical coagulation tank (150), a chemical supply pipe (154) connected to the chemical storage tank (153) supplies a certain amount of chemical, and a stirrer (151) stirs the treated water (W1) and the chemical to remove phosphorus from the treated water (W1).

[0074] The pressurized flotation tank (160) has the advantage of having a superior effect in removing suspended solids compared to a conventional sedimentation tank, a short retention time, and a small required area. In addition, the pressurized flotation tank (160) according to the present invention can improve the treatment efficiency of the aggregated suspended solids (B) by forcibly transporting the aggregated suspended solids (B) using bubble generating nozzles (166a, 166b, 166c) and an air injection nozzle (167).

[0075] FIG. 8 is a cross-sectional example diagram schematically illustrating the side cross-sectional configuration of a pressurized flotation tank (160) according to the present invention, and FIG. 9 is a cross-sectional example diagram schematically illustrating the planar cross-sectional configuration of a pressurized flotation tank (160).

[0076] The pressurized flotation tank (160) receives coagulated treated water discharged from the chemical coagulation tank (150) and floats particulate matter. The pressurized flotation tank (160) includes a flotation tank body (161) with a partition wall (161a) formed therein, a treated water collection unit (162), a coagulated suspended matter removal unit (164), a suspended matter storage tank (165), bubble generating nozzles (166a, 166b, 166c), an air injection nozzle (167), a treated water circulation pump (168), a bubble dissolution unit (169), and a compressor (169a).

[0077] The partition wall (161a) is provided at the inlet side of the flotation tank body (161) to induce suspended matter contained in the coagulated water to easily float to the surface.

[0078] A plurality of bubble generating nozzles (166a, 166b, 166c) are spaced apart and arranged at the bottom of the flotation tank body (161). The plurality of bubble generating nozzles (166a, 166b, 166c) supply circulating water (M) containing bubbles supplied from the bubble dissolving unit (169) to the flotation tank body (161). The bubble dissolving unit (169) forms circulating water containing bubbles by dissolving high-pressure air (A) supplied from the compressor (169a) into the coagulation treatment water (W1).

[0079] At this time, the bubbles (A) contained in the circulating water (M) containing air react with the suspended matter in the coagulated water, causing it to rise to the surface near the water surface without sinking to the bottom.

[0080] Here, the first bubble generating nozzle (166a) is positioned between the inlet of the flotation tank body (161) and the partition wall (161a), the second bubble generating nozzle (166b) is positioned inside the partition wall (161a), and the third bubble generating nozzle (166c) is positioned on the outlet side, spaced inward from the second bubble generating nozzle (166b).

[0081] It is desirable that the size of the first bubble (M1) generated from the first bubble generating nozzle (166a) be as small as possible. This is because the suspended matter contained in the coagulated water tends to settle to the bottom, so it is desirable to generate as many small bubbles as possible to attach to the surface of the suspended matter in order to make it float near the water surface.

[0082] It is preferable that the size of the second bubble (M2) generated from the second bubble generating nozzle (166b) is larger than the first bubble (M1), and it is preferable that the size of the third bubble (M3) generated from the third bubble generating nozzle (166c) is larger than the second bubble (M2).

[0083] The size of the bubbles increases as you go from the inlet side to the outlet side of the pressurized flotation tank (160) (M1 <M2,M3) 부상조본체(161)의 입구측 보다는 배출구 측에 부상한 응집된 부유물질의 현탁물질 입자가 더 크므로, 큰 물질 입자가 바닥으로 가라앉지 않게 하기위해 기포의 크기가 큰 것이 유리하기 때문이다.

[0084] The suspended matter contained in the coagulated treated water forms coagulated suspended matter (B) near the water surface, and is then transferred to the suspended matter storage tank (165) by means of the coagulated suspended matter removal port (164) positioned at the outlet side of the flotation tank body (161). The final treated water (W2) from which the suspended matter has been removed is partially discharged to the outside and partially supplied to the bubble dissolution unit (169) through a treated water collection unit (162) having a plurality of treated water collection ports (162a) and treated water discharge ports (162b) positioned at the lower side inside the flotation tank body (161).

[0085] Meanwhile, a plurality of air injection nozzles (167) are arranged on the inner wall surface along from the inlet side to the outlet side at the top of the floating body (161). The air injection nozzles (167) inject air (A) into the aggregated floating material (B) that has risen above the water surface, thereby forcibly moving the aggregated floating material (B) toward the aggregated floating material removal section (164).

[0086] The aggregated floating material removal unit (164) is provided in the form of a rotating belt, and hooks for forcibly moving aggregated floating material (B) to the floating material storage tank (165) may be provided at regular intervals on the belt surface.

[0087] The sludge (S) collected in the floating matter storage tank (165) is discharged to the outside, and the final treated water (W2) transferred to the treated water collection unit (162) is discharged.

[0089] At this time, a scum location detection unit for detecting the location of aggregated floating matter (B) is provided at each location on one side of each air injection nozzle (167). Multiple scum location detection units are provided at each location in a direction where the light-emitting unit (163a, 163c, 163e) and the receiver unit (163b, 163d, 163f) face each other. At locations where aggregated floating matter (B) exists, light (L) emitted from the light-emitting unit (163a, 163c, 163e) is blocked by the aggregated floating matter (B) and cannot be received by the receiver unit (163b, 163d, 163f).

[0090] A control unit (not shown) can detect the location of aggregated floating material (B) on the upper part of the float body (161) through the reception of light from the first light-emitting unit (163a) and the first receiver (163b), the second light-emitting unit (163c) and the second receiver (163d), and the third light-emitting unit (163e) and the third receiver (163f), and control the operation of the air injection nozzle (167) at the corresponding location.

[0091] The pressurized flotation tank (160) of the present invention effectively moves aggregated floating material (B) using a plurality of bubble generating nozzles (166a, 166b, 166c) and an air injection nozzle (167), so that while conventional pressurized flotation devices are operated at 5 to 7 atmospheres, it can be operated at a low pressure of 2.5 to 3 atmospheres. Therefore, energy saving efficiency can be improved.

[0093] The wastewater advanced treatment system according to the present invention having such a configuration uses a microbubble generator instead of the blower used in conventional aerobic tanks, so the energy cost of the aerobic tank can be reduced by more than 30%.

[0094] In addition, since the treated water is transferred from the aerobic tank to the anoxic tank by gravity flow without a separate pump, an internal return pump is not required, so energy costs for nitrogen removal can be reduced by 100%.

[0095] In addition, the application of a high-efficiency pressurized flotation tank can reduce energy consumption for phosphorus removal by more than 40%.

[0096] In addition, maximizing the oxygen transfer rate through a microbubble generator enables the removal of organic matter and stable nitrification, and increasing the nitrogen removal rate through appropriate automatic circulation.

[0097] In addition, by applying a membrane separation tank, the microbial concentration within the tank can be increased to enhance the removal efficiency of organic matter and nitrogen. Furthermore, perfect SS removal can be achieved through solid-liquid separation using membranes.

[0098] In addition, it can respond very strongly to fluctuations in inflow load by enhancing microbial retention and maximizing oxygen transfer rates, and phosphorus removal efficiency can be increased through the application of chemical coagulation and high-efficiency pressurized flotation.

[0099] In addition, the aeration method uses a mechanical microbubble generator instead of a blower and diffuser, which has the advantage of allowing external action to be taken without stopping the operation of the aeration tank in the event of a malfunction.

[0100] In addition, it is resistant to load fluctuations and easy to operate due to the maintenance of high microbial concentrations and the maximization of oxygen transfer rates.

[0101] In addition, by adopting a low-pressure flotation method in the pressurized flotation tank, the pressure burden on equipment and piping is reduced, thereby lowering the risk of damage.

[0102] In addition, since wastewater flows into the anaerobic tank, there is an advantage in that there is no need to supply carbon sources such as methanol for nitrogen removal.

[0104] The embodiments of the advanced wastewater treatment system of the present invention described above are merely illustrative, and those skilled in the art will readily understand that various modifications and equivalent alternative embodiments are possible therefrom. Therefore, it will be well understood that the present invention is not limited only to the forms mentioned in the detailed description above. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims. Furthermore, the present invention should be understood to include all modifications, equivalents, and substitutions within the spirit and scope of the present invention as defined by the appended claims. Explanation of the symbols

[0106] 100: Advanced wastewater treatment system 110: Anaerobic tank 111 : Inlet pipe 113 : Stirrer 115 : Circulating water supply pipe 116 : Circulating water pump 117 : Sludge return pipe 120 : Aerobic tank 130 : Microbubble generator 131 : Body 131a : Separator 131b : Lower space 131c : Inclined surface 131d : Upper space 131e: Spray nozzle 133: Treated water inlet pipe 135 : Air inlet pipe 137 : Mixing pipe 139 : Guide tube 140 : Membrane separation tank 141: Sedimentation membrane 143: Sludge discharge pipe 150 : Chemical coagulation tank 151 : Agitator 153 : Chemical storage tank 154 : Chemical supply pipe 160 : Pressurized flotation tank 161 : Flotation tank main body 161a: Bulkhead 161b: Treated water storage tank 161c: Water level control unit 162: Treated water collection unit 162a: Treatment collection inlet 162b: Treatment discharge outlet 162c: Treated water transfer pipe 163a: First light-emitting unit 163b: First receiver 163c: Second light emitter 163d: Second receiver 163e: Third light emitter 163f : Third receiver 164 : Aggregated floating matter removal section 165: Suspended Solids Retention Tank 166a: First Bubble Generating Nozzle 166b: Second bubble generating nozzle 166c: Third bubble generating nozzle 167 : Air injection nozzle 168 : Treated water circulation pump 169 : Bubble dissolution unit 169a : Compressor A : Air B: Aggregated suspended matter M: Air-containing circulating water S : Sludge W : Wastewater W1 : Treated water W2 : Final treatment water

Claims

Claim 1 An anaerobic tank (110) for removing nitrogen in incoming wastewater; an aerobic tank (120) in which organic matter oxidation and nitrification are performed in the treated water flowing in from the anaerobic tank (110), and phosphorus removal microorganisms absorb excess phosphorus; a membrane separation tank (140) for removing solid matter from the treated water passing through the aerobic tank (120) using an internally provided immersion membrane (141) with a pore size of 0.0001 to 0.4 μm, and returning a portion of the separated sludge to the anaerobic tank (110); a chemical coagulation tank (150) for removing phosphorus (P) by adding a coagulant to the treated water flowing in from the membrane separation tank (140); and a final treated water for releasing air in the form of bubbles into the treated water passing through the chemical coagulation tank (150) so that the coagulated suspended matter inside the treated water rises to the surface due to the buoyancy of the bubbles, is removed, and then discharged. The system includes a pressurized flotation tank (160), and a circulating water supply pipe (115) is connected between the anoxic tank (110) and the aerobic tank (120) to circulate and supply treated water from inside the anoxic tank (110) to the aerobic tank (120). The treated water flowing into the aerobic tank (120) flows from the anoxic tank (110) through the circulating water supply pipe (115), and the treated water mixed with microbubbles via a microbubble generator (130) is supplied to the bottom portion of the aerobic tank (120), and oxygen is delivered by the microbubbles. As more treated water is circulated and supplied to the aerobic tank (120) than the flow rate of wastewater flowing into the anoxic tank (110), the treated water flowing into the aerobic tank (120) is treated within the aerobic tank (120), and the excess treated water is returned to the anoxic tank (110) by a natural gravity flow method. The microbubble generating device (130) is returned and comprises: a body (131) in which the internal space is divided into an upper space (131d) and a lower space (131b) by a separator (131a); a treated water inlet pipe (133) coupled to the circulating water supply pipe (115) to supply treated water (W1) to the upper space; and an air inlet pipe (135) provided to penetrate downward through the upper space to supply air to the central area of ​​the lower space (131b);It includes a plurality of spray nozzles (131e) coupled to the above-mentioned isolation plate (131a) and spraying treated water flowing into the upper space (131d) into the lower space (131b); a funnel-shaped inclined surface (131c) is provided on the spray path of the spray nozzle (131e) in the lower space (131b), the inner diameter of which gradually narrows toward the bottom; the spray nozzle (131e) is coupled to spray treated water in an obliquely inclined direction along the circumferential direction of the inclined surface (131c); and the treated water sprayed from the spray nozzle (131e) flows spirally along the inclined surface (131c); and the pressurized flotation tank (160) comprises a flotation tank body (161) into which treated water flows from the chemical coagulation tank (150); and a coagulated area provided opposite to the treated water inflow area of ​​the flotation tank body (161). A floating substance storage tank (165) for collecting floating substances; a bubble dissolving unit (169) for dissolving bubbles in the treated water discharged from the floating tank body (161); a plurality of first bubble generating nozzles (166a) provided below the treated water inflow area of ​​the floating tank body (161) for spraying circulating water containing bubbles supplied from the bubble dissolving unit (169) into the floating tank body (161); a plurality of second bubble generating nozzles (166b) arranged inside the floating tank body (161) spaced apart from the first bubble generating nozzles (166a) and generating bubbles larger than the size of the bubbles generated by the first bubble generating nozzles (166a); and a plurality of second bubble generating nozzles (166b) provided below the treated water discharge area of ​​the floating tank body (161) and generating bubbles larger than the size of the bubbles generated by the second bubble generating nozzles (166b). A third bubble generating nozzle (166c) and;An energy-saving advanced wastewater treatment system characterized by comprising a plurality of air injection nozzles (167) provided at regular intervals along the longitudinal direction on the upper inner wall surface of the above-mentioned floating tank body (161) to inject air into aggregated floating matter floating on the water surface and move the aggregated floating matter to the above-mentioned floating matter storage tank (165), and the microbubble generating device (130) supplies the treated water mixed with microbubbles to the aerobic tank (120) by causing the treated water flowing in through the circulating water supply pipe (115) to flow spirally along the internal inclined surface (131c), and at the same time, the treated water supplied to the aerobic tank (120) is automatically returned from the aerobic tank (120) to the anoxic tank (110) by a natural gravity flow method without a separate internal return pump. Claim 2 delete Claim 3 delete

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