JP2007209890A - Treatment method and apparatus for organic wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment method and apparatus for coagulating organic wastewater and then applying floatation separation to the coagulated organic wastewater in a floating tank, the method and apparatus achieving reduction in sludge discharged from the wastewater treatment apparatus or generation of no sludge. <P>SOLUTION: Organic wastewater is led to the coagulation tank 11 of a first dissolved-air floatation apparatus 10, where an inorganic coagulant like PAC is added to the organic wastewater together with floating scum returned from a floating separating chamber 12B and the organic wastewater is subjected to coagulation. Coagulated water is sent to the floating tank 12, mixed with fine bubbles from a fine bubble generator 13 and a polymer coagulant serving as a coagulant aid in a mixing chamber 12A, and then separated by floatation in the floating separation tank 12B. Floating scum from the floating separation tank 12B is returned to the coagulation tank 11. While, part of the separated water is used as water for generating fine bubbles of the fine bubble generator 13, the remaining being sent to a biological treatment device 20. Biologically treated water is subjected to coagulation and dissolved-air floatation in a second dissolved-air floatation apparatus 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and method in which organic wastewater is subjected to flocculation treatment and then subjected to floating separation treatment.

  Japanese Patent Application Laid-Open No. 2002-113471 describes that the organic waste water is agglomerated and then subjected to floating separation treatment.

In Japanese Patent Laid-Open No. 2002-113471, the floating scum generated by the floating separation treatment is acid-treated to elute the inorganic flocculant component (aluminum ion or iron ion), and the eluted inorganic flocculant-containing liquid is returned to the coagulation tank. Insoluble sludge produced by acid treatment is dehydrated with a dehydrator and discarded.
JP 2002-113471 A

  In the pressurized flotation device, soluble organic matter that cannot be agglomerated cannot be levitated and separated, so it must be treated by biological treatment such as an aeration tank installed in the subsequent stage. An object of the present invention is to treat a part of soluble organic matter that cannot be removed by conventional coagulation and pressure flotation, and to reduce aeration power by reducing the burden of biological treatment in the subsequent stage.

  Moreover, in the said Unexamined-Japanese-Patent No. 2002-113471, the insoluble sludge which occupies most floating scum is not returned to a coagulation tank, but is discarded, Therefore The amount of sludge to discard is large.

  Another object of the present invention is to provide a wastewater treatment apparatus and method for coagulating organic wastewater and then subjecting it to a floatation tank so as to reduce sludge discharged from the wastewater treatment apparatus. An apparatus and method is provided.

  The wastewater treatment apparatus according to claim 1 is a wastewater treatment apparatus having a coagulation tank for organic wastewater, and a levitation tank that floats and separates into a floating scum and separated water by mixing fine bubbles with the effluent water of the coagulation tank. And a scum returning means for returning at least a part of the floating scum separated in the floating tank to the aggregating tank.

  A wastewater treatment apparatus according to a second aspect is characterized in that, in the first aspect, a biological treatment apparatus for biologically treating the separated water from the levitation tank is provided.

  The wastewater treatment apparatus according to claim 3 is a first levitation unit that flocculates and separates into a first levitation scum and a first separation water by mixing fine bubbles in the effluent of the organic effluent and the outflow water of the coagulation basin. A tank, a biological treatment apparatus for biologically treating the first separated water, and mixing fine bubbles with the biologically treated water from the biological treatment apparatus to float and separate the second floating scum and the second separated water. A second levitation tank and scum return means for returning at least a part of at least one of the first levitation scum and the second levitation scum to the agglomeration tank. It is.

  A wastewater treatment apparatus according to a fourth aspect of the present invention is the biological organism according to the second or third aspect, wherein the biological treatment apparatus includes an aeration tank and a fluid carrier that is housed in the aeration tank so as to be flowable and carries a biofilm. It is a membrane-type aerobic treatment device.

  The waste water treatment apparatus according to claim 5 is the mixing tank according to any one of claims 1 to 4, wherein the levitation tank is mixed with fine bubbles mixed with water to be subjected to the levitation separation process. The chamber is divided into a floating separation chamber into which mixed water from the mixing chamber is introduced and the scum rises.

  A waste water treatment apparatus according to a sixth aspect is characterized in that in the fifth aspect, a coagulation aid adding means for adding a coagulation aid into the mixing chamber is provided.

  According to a seventh aspect of the present invention, there is provided the waste water treatment apparatus according to the fifth aspect, wherein the mixing chamber is provided with an introduction portion for introducing water to be floated and separated into the mixing chamber. On the other hand, after adding the coagulation aid from the coagulation aid addition means, the fine bubbles are added from the microbubble addition means, and the microbubble addition means is arranged directly with respect to the coagulation aid addition means. It is characterized by being.

  A wastewater treatment apparatus according to an eighth aspect of the present invention includes the scum aerobic treatment means according to any one of the first to seventh aspects, wherein the scum aerobic treatment means performs aerobic treatment on at least a part of the scum returned by the scum return means. It is what.

  A wastewater treatment apparatus according to a ninth aspect is characterized in that, in any one of the first to eighth aspects, the returned scum is mixed with the organic wastewater and then introduced into the aggregation tank. Is.

  An organic wastewater treatment method according to a tenth aspect is characterized in that the organic wastewater is treated by the wastewater treatment apparatus according to any one of the first to ninth aspects.

  An organic wastewater treatment method according to an eleventh aspect is the wastewater treatment apparatus according to the fourth aspect, wherein the wastewater treatment apparatus is the wastewater treatment apparatus according to the fourth aspect, wherein aeration of the biological treatment apparatus is intermittently stopped, and the biological treatment is performed. The apparatus is operated in an aerobic-anaerobic cycle.

  In the present invention, after the organic waste water is agglomerated, the floated and separated scum is introduced directly into the agglomeration tank or after being mixed with the organic waste water, and the scum is circulated. When the floating scum is circulated in this manner, activated sludge is generated.

When a part of the soluble BOD in the organic waste water is taken into the microorganism body of the activated sludge, it becomes a storage material.

  Moreover, since the surface of activated sludge is generally sticky, some suspended BOD is adsorbed by activated sludge.

When activated sludge that has taken in or adsorbed BOD in this way is introduced into the levitation tank, the levitation tank is in an aerobic environment due to microbubbles. Components are oxidatively decomposed. Thereby, the BOD component in the organic waste water is oxidized and decomposed and removed from the water.

  In addition, when the storage substance and the adsorbed BOD component are oxidatively decomposed in the levitation tank, the activated sludge can take up the soluble BOD again or adsorb the suspended BOD.

Thus, according to the present invention, the amount of sludge discharged from the waste water treatment device is reduced.

In addition, when a biological treatment apparatus is installed on the rear stage side of the levitation tank, the load on the biological treatment apparatus is reduced, and the aeration power for aerobic treatment is reduced. Can be reduced.

In the present invention, a second levitation tank may be provided after the biological treatment apparatus, and at least a part of the levitation scum of the second levitation tank may be returned to the coagulation tank. Also in this case, the same effects as described above are exhibited.

Note that the sludge introduced into the second levitation tank has passed through the biological treatment apparatus, and microorganisms are growing, so that the BOD removal effect in the second levitation tank is improved.

When the bioreactor is a fluidized biofilm aerobic treatment device in which a carrier is placed in an aeration tank, the carriers are rubbed together, and activated sludge microorganisms grown on the surface of the carrier flow out and are introduced into the second levitation tank. . Since this activated sludge has high activity, the amount of soluble BOD taken up is large when it comes into contact with sewage.

When the aeration of the biological treatment apparatus is periodically stopped and the anaerobic-aerobic cycle is repeated, the activated sludge has the ability to cope with environmental changes. Since the uptake substance cannot be oxidatively decomposed in an anaerobic state, it can be converted into a storage substance, and the ability to take up BOD in the liquid into the body is increased.

In the present invention, when the levitation tank is divided into a mixing chamber and a levitation separation chamber, and a coagulation aid and fine bubbles are added to the mixing chamber, a strong bubble-containing floc contained inside the bubbles is generated. The bubble-containing floc containing bubbles inside oxidizes the stored material that the activated sludge microorganisms have taken into the body by the biological treatment device using oxygen in the bubbles contained in the floc until it is mixed with organic wastewater. Since it decomposes, the amount of soluble BOD uptake when mixed with sewage increases. Moreover, since the floc contains air bubbles, the specific gravity is low and the separation performance in the levitation tank is also high.

  In the present invention, the scum returned to the agglomeration tank is subjected to aerobic treatment, so that the BOD component in the microorganisms in the scum can be consumed or the scum can be prevented from decaying.

In the present invention, the return scum is mixed with the organic waste water and then introduced into the agglomeration tank, whereby the effect of the sludge of the scum adsorbing the BOD suspended component increases, and this effect and the agglomeration effect by the aggregating agent are synergistic. In addition, the aggregation process is efficiently performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system diagram showing a first embodiment of the organic waste water treatment apparatus of the present invention. Examples of organic wastewater include, but are not limited to, sewage, food processing, factory wastewater such as paper pulp, fiber, and petrochemical, and wastewater from restaurants and gas stations.

  The organic waste water is introduced into the agglomeration tank 11 of the first pressurized flotation separation apparatus 10, and an inorganic flocculant such as PAC is added together with the flotation scum returned from the flotation separation chamber 12B described later to be agglomerated. The agglomerated water is fed to the levitation tank 12, mixed with the fine bubbles from the fine bubble generator 13 and the polymer flocculant as an agglomeration aid in the mixing chamber 12A, and then levitated and separated in the flotation separation chamber 12B. The The floating scum from the floating separation chamber 12B is returned to the aggregation tank 11. On the other hand, a part of the separated water is used as water for generating fine bubbles in the fine bubble generating device 13, and the remaining part is fed to the biological treatment device 20.

  The fine bubble generating device 13 and the fine bubble generating device 33 to be described later are of a type that generates fine bubbles by pressurizing the water for generating fine bubbles to dissolve the gas and then reducing the pressure to generate fine bubbles. In the flotation tank 12 of the flotation separation apparatus 10 and the flotation tank 32 of the second pressurized flotation separation apparatus 30 described later, fine bubbles are generated by the fine bubble generation devices 13 and 33 and at the same time, fine bubbles and coagulation assistance are added to the agglomerated water. It is comprised so that an agent may be mixed.

  The biological treatment apparatus 30 preferably uses a biofilm, and particularly preferably a contact aeration bioreaction apparatus or a biofilm aerobic treatment apparatus into which a fluid carrier such as a sponge carrier is introduced.

  In the second pressurized flotation separation device 30, the biologically treated water from the biological treatment device 20 is agglomerated by adding an inorganic flocculant such as PAC in the agglomeration tank 31. The agglomerated water is fed to the floating tank 32, mixed with the fine bubbles and the polymer flocculant from the fine bubble generating device 33 in the mixing chamber 32A, and then floated and separated in the floating separation chamber 32B. The floating scum from the floating separation chamber 32B is discharged out of the system. Since the separated water has a sufficiently high water quality, a part of the separated water is used as water for generating fine bubbles in the fine bubble generating device 33, and the remaining part is discharged out of the system as treated water.

  As the inorganic flocculant added to the flocculation tanks 11 and 31, inorganic flocculants such as PAC, sulfuric acid band (aluminum sulfate), ferric chloride, ferrous sulfate, ferric sulfate, etc. can be used. The amount is preferably about 0.1 to 10 times, particularly about 0.5 to 2 times the concentration of pollutants in the water to be agglomerated.

  In addition, as a polymer flocculant to be added to the levitation tanks 12 and 32 as a coagulation aid, poly (meth) acrylamide, its hydrolyzate, poly (meth) acrylic acid, (meth) acrylamide and alkylamino (meta) ) Nonionic, anionic, cationic or amphoteric polymer flocculants such as acrylamide copolymers can be used.

  The addition amount of the polymer flocculant is usually about 0.5 to 5 mg / L with respect to the amount of drainage.

  As the fine bubble generators 13, 23, 33, a vortex pump type can be used.

  In this embodiment, the scum floated and separated in the floating separation chamber 12B is introduced into the aggregation tank 11, and the scum is circulated. When the floating scum is circulated in this manner, activated sludge is generated. Part of the soluble BOD in the organic waste water is taken into the body of the microorganisms of the activated sludge and becomes a storage material. Further, since the surface of the activated sludge is sticky, a part of the suspended BOD is adsorbed on the activated sludge.

When activated sludge that has taken in or adsorbed BOD is introduced into the levitation tank 12, the levitation tank 12 is in an aerobic environment due to fine bubbles. The adsorbed BOD component is oxidatively decomposed. Thereby, the BOD component in the organic waste water is oxidized and decomposed and removed from the water.

  In addition, when a storage substance and adsorption | suction BOD component are oxidatively decomposed in the levitation tank 12, it becomes possible for activated sludge to take in soluble BOD again or to adsorb | suck suspension BOD.

  In this way, the amount of sludge discharged from the waste water treatment device is reduced by returning the floating scum to the coagulation tank 11.

  Moreover, the load of the biological treatment apparatus 20 installed on the rear stage side of the levitation tank 12 may be reduced, the tank volume of the biological treatment apparatus 20 may be reduced, or the aeration power for aerobic treatment may be reduced. It becomes possible.

  When this bioreactor 20 is a fluidized biofilm type aerobic treatment device in which a carrier is placed in an aeration tank, the carriers are rubbed together, and activated sludge microorganisms grown on the surface of the carrier flow out, and the second pressurized floating separation is performed. Introduced into the apparatus 30. Since the activated sludge from the biological treatment apparatus 20 is activated sludge having high activity, the amount of soluble BOD taken up when it comes into contact with the sewage increases.

  In addition, when the aeration of the biological treatment apparatus 20 is periodically stopped and the anaerobic-aerobic cycle is repeated, the activated sludge has an ability to cope with environmental changes. Since the uptake substance cannot be oxidatively decomposed in an anaerobic state, it can be converted into a storage substance, and the ability to take up BOD in the liquid into the body is increased.

  In this embodiment, the levitation tanks 12 and 32 are divided into mixing chambers 12A and 32A and levitation separation chambers 12B and 32B, and a coagulation aid and fine bubbles are added to the mixing chambers 12A and 32A. A strong bubble-containing floc contained in is produced. The bubble-containing floc containing bubbles inside oxidizes the stored material that the activated sludge microorganisms have taken into the body by the biological treatment device using oxygen in the bubbles contained in the floc until it is mixed with organic wastewater. Since it decomposes, the amount of soluble BOD uptake when mixed with sewage increases. Moreover, since the floc contains air bubbles, the specific gravity is low and the separation performance in the levitation tank is also high.

  FIG. 2 is a system diagram showing a second embodiment of the waste water treatment apparatus of the present invention.

  In this embodiment, the floating scum from the floating separation chamber 12B of the first pressurized floating separation apparatus 10 is discharged out of the system, and instead, the floating scum from the floating separation chamber 32B of the second pressurized floating separation apparatus 30 is discharged. Is returned to the agglomeration tank 11. Other configurations are the same as those in FIG. 1, and the same reference numerals indicate the same parts.

  In this embodiment, the floating scum containing activated sludge in which microorganisms are propagated is returned to the agglomeration tank 11 via the biological treatment apparatus 20, so that a BOD removal performance equal to or higher than that in the case of FIG. 1 is obtained. be able to.

  FIG. 3 is a system diagram showing a third embodiment of the waste water treatment apparatus of the present invention.

  In this embodiment, the floating scum from the floating separation chambers 12B and 32B of the first and second pressurized floating separation devices 10 and 20 is returned to the agglomeration tank 11, respectively, and other configurations are as follows. The same reference numerals denote the same parts as those in FIG.

  According to this embodiment, since the floating scum of each of the floating tanks 12 and 32 is returned to the agglomeration tank 11, the amount of discharged scum can be remarkably reduced. When the amount of scum returned to the agglomeration tank 11 is excessive, a part of the scum may be discharged out of the system.

  FIG. 4 is a system diagram showing a fourth embodiment of the present invention.

  In this embodiment, the floating scum from the floating separation chambers 12B and 32B of the first and second pressurized floating separation apparatuses 10 and 20 is introduced into the scum storage tank 40, subjected to aerobic treatment, and then returned to the agglomeration tank 11. It is what you do. The other structure of FIG. 4 is the same as that of FIG. 3, and the same code | symbol has shown the identical part.

  In this embodiment, the same effect as in FIG. 3 is obtained. Even if the floating scum amount in the floating tanks 12 and 32 fluctuates, the return scum amount introduced into the agglomeration tank 11 can be leveled because the scum storage tank 40 is provided.

  The scum storage tank 40 may be provided with aerobic treatment means such as a diffuser tube so that BOD components in the microorganisms are consumed during the storage period in the storage tank 40, or sludge decay is prevented.

  FIGS. 5 and 6 are system diagrams showing fifth and sixth embodiments of the present invention.

  In these embodiments, the mixing tank 8 is disposed in the previous stage of the first pressurized flotation separation apparatus 10, and the organic waste water and the return scum from the flotation separation chambers 12 </ b> B and 32 </ b> B are mixed in the mixing tank 8. It is introduced into the agglomeration tank 11.

  Other configurations in FIG. 5 are the same as those in FIG. 3, other configurations in FIG. 6 are the same as those in FIG. 4, and the same reference numerals denote the same parts.

  In the embodiment shown in FIGS. 5 and 6, the same effects as those shown in FIGS. The return scum is mixed with the organic wastewater in the mixing tank 8 in advance and then introduced into the coagulation tank 11, so that the effect of sludge adsorbing the BOD suspended component and the coagulation effect by the coagulant synergize efficiently. Aggregation is performed.

  Next, the configuration of a pressurized levitation separator 50 suitable for use in the pressurized levitation separators 10 and 30 will be described with reference to FIGS.

  FIG. 7 is a longitudinal sectional view in the longitudinal direction of this pressurized flotation separation device, FIG. 8 is a sectional perspective view showing the configuration in the vicinity of the partition wall, FIG. 9 is a sectional view showing the circulation state of water in the mixing chamber, FIG. 10 is a sectional view taken along line XX of FIG. 9, and FIG. 11 is a sectional view taken along line XI-XI of FIG.

  The inside of the tank body 53 having a substantially rectangular shape in plan view is partitioned by the partition wall 51 and the partition wall 52, so that the aggregation reaction chamber 60 corresponding to the aggregation tank 11 or 31 and the mixing corresponding to the mixing chamber 12A or 32A are mixed. A floating separation chamber 80 corresponding to the chamber 70 and the floating separation chamber 12B or 32B is formed in this order. The chambers 60, 70, 80 are arranged in the longitudinal direction of the tank body 53, and the walls 51, 52 are extended in the short direction, that is, the width direction of the tank body 53.

  An outlet 66 for communicating the chambers 60 and 70 is formed at the center in the width direction at the bottom of the partition wall 51. The upper end of the partition wall 51 extends upward from the water surface between the tank bodies 53.

  The partition wall 52 is erected from the tank body bottom surface 53 b, and the upper end thereof is lower than the water surface between the tank bodies 53.

  Each wall 51, 52 is connected to both side surfaces 53a of the tank body.

  The agglomeration reaction chamber 60 is fed with raw water (raw water from the organic waste water or mixing tank 8 in the case of the first pressurized flotation separator 10, biological organism in the case of the second pressurized flotation separator 20 through the raw water pipe 61. Biologically treated water from the treatment apparatus 20 is introduced, and an inorganic flocculant and an alkali agent can be supplied through the supply pipes 62 and 63, respectively. A pH meter 64 for detecting the pH of water in the agglomeration reaction chamber 60 is installed, and an alkaline agent injection pump (not shown) is operated so that the detected value of the pH meter 64 falls within a predetermined range.

  The water in the agglomeration reaction chamber 60 is agitated by an agitator 65 and agglomerated.

  Aggregation reaction water flows into the mixing chamber 70 through the outlet 66 and flows along the tank bottom surface 53b in the vicinity of the center in the width direction of the mixing chamber 70. In the tank bottom surface 53b, a nozzle 73 for discharging pressurized water is provided in the center in the width direction and relatively close to the partition wall 52. The tip of the nozzle 73 slightly protrudes from the tank body bottom surface 53b.

  A polymer agglomeration aid solution supply pipe 77 is provided in the vicinity of the nozzle 73 and closer to the outlet 66 than the nozzle 73. The supply pipe 77 is installed upward so as to discharge the polymer aggregation aid solution upward.

  The level of the upper end of the supply pipe 77 is higher than the upper end of the nozzle 73.

  In this embodiment, water is taken out from the lower part of the levitation separation chamber 80 through a pipe 71, air is pressurized and dissolved in the fine bubble generator 72 corresponding to the fine bubble generator 13 or 33, and this pressurized water is supplied to the nozzle. 73.

  In this embodiment, the nozzle 73 and the supply pipe 77 are arranged in a vertically lower region of an inclined partition upper portion 52b described later. In this embodiment, only one nozzle 73 and supply pipe 77 are provided at the center of the tank bottom surface 53b in the width direction.

  The polymer agglomeration aid solution from the supply pipe 77 is added to the agglomerated water from the outflow port 66, and pressurized water from the nozzle 73 is added thereto, and these are mixed and mainly near the center in the width direction of the partition wall 52. Ascend along. The partition 52 is a vertical portion 52a that is substantially vertical (preferably within ± 10 ° with respect to the vertical plane) except for the upper portion 52b, and the upper portion 52b is inclined toward the partition wall 51.

  The upward flow flows substantially vertically upward along the vertical portion 52 a of the partition wall 52. Next, the upward flow is guided by the inclined partition upper part 52 b to change the flow direction toward the partition wall 51, and becomes a downward flow descending along the partition wall 51 when reaching the vicinity of the partition wall 51. The downward flow that has flowed to the lower part of the partition wall 51 flows toward the partition wall 52 through the tank bottom surface 53 b while joining with the agglomerated water from the outlet 66. In this manner, a vertical circulation flow is formed in the mixing chamber 52 as shown in FIG. And while circulating, fine bubbles generated from the pressurized water adhere to the aggregates, and at the same time, the aggregates in the aggregation reaction water are coarsened by the polymer aggregation assistant, so that large bubbles containing bubbles are contained inside. Become a flock.

  The water circulation state in the mixing chamber will be described in more detail with reference to FIGS.

  Aggregation reaction water flows into the mixing chamber 70 from the outlet 66, and the inflowed water flows toward the partition wall 52 along the tank bottom surface 53b in the vicinity of the center in the tank width direction.

  A polymer aggregation assistant solution is added from the supply pipe 77 to the flow along the tank bottom surface 53b, and pressurized water is added upward from the nozzle 73. The polymer agglomeration aid is drawn into a large momentum of the pressurized water and flows upward while being mixed with the pressurized water. Since the nozzle 73 is disposed relatively close to the partition wall 52, the flow that attempts to change the flow upwards against the partition wall 52 and the upward pressurized water flow overlap each other, thereby the vicinity of the partition wall 52. In the vicinity of the central part of the tank body in the width direction, an upward flow with a relatively high flow velocity is formed partially upward. In the vicinity of both sides of the partition wall 52, an upward flow with a relatively low flow rate is formed, or when the width of the mixing chamber 70 is large, a downward flow is formed.

  The upward flow along the vicinity of the center of the partition wall 52 in the width direction hits the inclined partition wall upper portion 52b, changes the flow direction toward the partition wall 51 and flows near the water surface of the mixing chamber 70 toward the partition wall 51. Since the ascending flow velocity in the vicinity of the center in the width direction is larger than that on both sides in the width direction, the flow toward the partition wall 51 moves from the vicinity of the center in the width direction near the partition wall 52 to the entire width direction of the partition wall 51 as shown in FIG. It becomes a spreading radial flow. The flow spread over the entire partition wall 51 then descends along the partition wall 51 and moves toward the partition wall 52 so as to converge in the vicinity of the center of the tank bottom surface 53b in the width direction along with the flow from the outlet 66. Flowing. And when it reaches the vicinity of the partition 52, it raises along the partition 52 so that the width direction center side may become a high flow velocity as mentioned above.

  As described above, in the mixing chamber 70, in addition to the up-and-down circulation of the upward flow along the partition wall 52 and the downward flow along the partition wall 51, after rising along the partition wall 52, it spreads in the width direction as being separated from the partition wall 52, Then, after descending along the partition wall 51, vertical and horizontal circulation flows are formed in which the circulation in the width direction converging at the center in the width direction is superimposed. For this reason, in the mixing chamber 2, the flocculated water, the polymer flocculating aid solution, and the pressurized water are mixed evenly.

  In addition, the partition upper part 52b is inclined toward the partition wall 51, and the upward flow along the partition wall 52 changes the flow direction toward the partition wall 51, so that the rising water crosses over the partition wall 52 in a short-circuited manner and rises to the separation chamber. No flow to 80.

  As a result, the flocs are supplied to the levitation separation chamber 80 in a state where the flocculated water and the polymer flocculation aid solution are sufficiently mixed with the pressurized water, and the bubbles are sufficiently contained in the flocs, and the flocs are efficiently levitated and separated. Is done.

  Moreover, in this embodiment, the polymer coagulation assistant solution is added from the supply pipe 77 to the coagulation reaction water from the outlet 66, and then pressurized water is added from the nozzle 73. For this reason, bubbles adhere to the aggregate in the aggregation reaction water, and at the same time, the polymer aggregation aid comes into contact with the aggregate, and the polymer aggregation assistant easily binds to the aggregate surface. As a result, small agglomerates in the agglomeration reaction water are bound to each other by the polymer agglomeration aid, and are easily grown. Since the grown coarse floc contains bubbles inside the floc, the rising speed is high and the bubbles are difficult to separate from the floc. For this reason, the levitating separation process is efficiently performed.

  The floated flock is discharged to a sludge receiving chamber 82 by a scraper 81 such as a skimmer or a scraper and taken out via a discharge pipe 83.

  The sludge settled in the floating separation chamber 80 is returned to the agglomeration tank 11 or the mixing tank 8 via the pipe 84 or discharged out of the system.

  The clean water is extracted from the midway in the vertical direction of the levitation separation chamber 80 by the pipe 85, and is taken out via a water level adjusting tank (not shown). This water level adjustment tank is for adjusting the water level in the tank body 53.

  The level difference between the upper end of the nozzle 73 and the upper end of the supply pipe 77 is preferably 150 mm or less, particularly about 20 to 100 mm.

  The horizontal distance between the nozzle 73 and the supply pipe 77 is preferably 100 mm or less, particularly preferably 50 mm or less, and the mixing efficiency of the polymer coagulant aid is improved when the distance between the nozzle 73 and the supply pipe 77 is as short as possible.

  In this embodiment, since the bottom surface of the agglomeration reaction chamber 60 and the bottom surface of the mixing chamber 70 are flush, the agglomerated water from the agglomeration reaction chamber 60 flows along the tank bottom surface 53b without disturbing the flow. It passes through the outlet 66 and flows in the center in the width direction along the bottom surface of the mixing chamber 70. In order to prevent this flow from spreading laterally or upward, a relatively short tunnel-shaped guide member may be connected to the outlet 66.

  In the above embodiment, one outlet 66, one supply pipe 77, and one nozzle 73 are provided, but two may be provided, or three or more may be provided.

It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a systematic diagram of the waste water treatment equipment concerning an embodiment. It is a longitudinal cross-sectional view of the longitudinal direction of a pressurization floating separator. It is a cross-sectional perspective view which shows the structure of the partition wall vicinity of FIG. It is sectional drawing which shows the circulation condition of the water in the mixing chamber of FIG. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is the XI-XI sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st pressurization floating separation apparatus 20 2nd pressurization floating separation apparatus 11,31 Coagulation tank 12,32 Floating tank 12A, 32A Mixing chamber 12B, 32B Flotation separation chamber 13,33,72 Fine bubble generator 51 Partition wall 52 Partition wall 53 Tank 60 Aggregation reaction chamber 65 Stirrer 66 Outflow port 70 Mixing chamber 80 Floating separation chamber

Claims (11)

An organic waste water agglomeration tank;
In a wastewater treatment apparatus having a levitation tank that mixes fine bubbles with the effluent water of this agglomeration tank and floats and separates into floating scum and separated water
A wastewater treatment apparatus comprising scum returning means for returning at least a part of the floating scum separated in the floating tank to the aggregating tank.   The wastewater treatment apparatus according to claim 1, further comprising a biological treatment apparatus that biologically treats the separated water from the levitation tank. An organic waste water agglomeration tank;
A first levitation tank that mixes microbubbles with the outflow water of the coagulation tank and floats and separates into a first levitation scum and first separation water;
A biological treatment apparatus for biologically treating the first separated water;
A second levitation tank that mixes fine bubbles with the biologically treated water from the biological treatment apparatus and floats and separates into the second floating scum and the second separated water;
A wastewater treatment apparatus comprising: a scum returning means for returning at least a part of at least one of the first and second floating scums to the agglomeration tank.   The biological treatment apparatus according to claim 2 or 3, wherein the biological treatment apparatus is a fluidized biofilm aerobic treatment apparatus having an aeration tank and a fluid carrier that is accommodated in the aeration tank so as to be flowable and carries a biofilm. Wastewater treatment equipment characterized by.   5. The levitation tank according to claim 1, wherein the levitation tank has a mixing chamber in which fine bubbles are mixed with water to be subjected to the levitation separation process to form mixed water, and mixing from the mixing chamber. A wastewater treatment apparatus characterized by being partitioned into a floating separation chamber into which water is introduced and a scum rises.   6. The waste water treatment apparatus according to claim 5, further comprising a coagulation aid adding means for adding a coagulation aid into the mixing chamber. In Claim 5, the mixing chamber is provided with an introduction portion for introducing water to be floated and separated into the mixing chamber.
After adding the coagulation aid from the coagulation aid adding means to the water from the introduction part, the fine bubbles are added from the microbubble addition means, and the fine bubbles are added to the coagulation aid addition means. A wastewater treatment apparatus characterized in that the adding means is directly arranged.   8. The waste water treatment apparatus according to claim 1, further comprising scum aerobic treatment means for aerobically treating at least a part of the scum returned by the scum return means.   The wastewater treatment apparatus according to any one of claims 1 to 8, wherein the scum to be returned is mixed with the organic wastewater and then introduced into the agglomeration tank.   Organic wastewater is processed with the wastewater treatment apparatus of any one of Claim 1 thru | or 9, The processing method of the organic wastewater characterized by the above-mentioned. In claim 10, the waste water treatment apparatus is the waste water treatment apparatus according to claim 4,
An organic wastewater treatment method characterized by intermittently stopping aeration of the biological treatment apparatus and operating the biological treatment apparatus in an aerobic-anaerobic cycle.

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