JP2008284427A - Apparatus and method for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating waste water, in each of which raw sludge separated from organic waste water can be used effectively and organic waste water can be treated biologically, satisfactorily stably and efficiently. <P>SOLUTION: The apparatus 100 for treating waste water, in which granulated sludge obtained by agglomerating and granulating microbial sludge is used, is provided with: a first sedimentation basin 1 for separating organic waste water into raw sludge and the water to be treated; a biological treatment tank 2A for biologically treating the water to be treated under an aerobic condition; a final sedimentation basin 3 for separating the biologically-treated water from the biological treatment tank 2A into separated water and separated sludge; an acid production tank 12 for producing an organic acid by fermenting the raw sludge; a granulated sludge production tank 20 for producing granulated sludge from a liquid raw material containing the organic acid; and a first granulated sludge supplying line L19A for supplying the granulated sludge produced in the granulated sludge production tank 20 to the biological treatment tank 2A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method using granulated sludge formed by collecting and granulating microbial sludge.

  An activated sludge method using microbial sludge is known as a method for treating organic wastewater such as sewage. In a treatment tank that contains microbial sludge and is maintained in an aerobic condition by aeration or the like, organic substances, particularly carbon-based organic compounds, contained in organic wastewater are decomposed and removed by metabolism of microorganisms.

In addition to carbon-based organic compounds, organic wastewater contains compounds such as nitrogen-containing compounds and phosphorus-containing compounds that cause eutrophication of the sea and rivers. Microbial sludge consists of various microorganisms, and it is known that microorganisms that metabolize these compounds are classified into the following four groups according to their physiological characteristics (see Non-Patent Document 1).
(I) heterotrophic organisms that grow using a carbon-based organic compound under aerobic conditions (in the presence of oxygen),
(Ii) autotrophic bacteria (so-called nitrifying bacteria) that oxidize ammonia nitrogen to nitrate nitrogen under aerobic conditions (in the presence of oxygen),
(Iii) facultative anaerobic bacteria (so-called denitrifying bacteria) that perform anaerobic conditions (under no dissolved oxygen), nitrate respiration, nitrite respiration,
(Iv) Bacteria that accumulate a large amount of polyphosphoric acid in cells by soaking alternately under anaerobic conditions (under the absence of oxygen, nitric acid / nitrite) and aerobic conditions (so-called phosphorus accumulating bacteria) .

In Non-Patent Document 1, in addition to decomposing and removing carbon-based organic compounds by controlling the operating conditions of the activated sludge method and artificially realizing conditions suitable for each microorganism belonging to the above four groups, biology It is described that it can perform denitrification and biological dephosphorization.
Supervised by the Sewerage Department, City Bureau of the Ministry of Construction, “Sewerage Facilities Planning and Design Guidelines and Explanation Part 2 -1994 Edition”, 2nd edition, Japan Sewerage Association, November 25, 1994, p. 14-15

  The wastewater treatment method that combines the removal of organic compounds with biological denitrification and biological dephosphorization can be applied to organic compounds (mainly BOD components), nitrogen-containing compounds, and phosphorus-containing compounds without using chemicals. It has the advantage that it can be removed. However, since each compound is processed using the metabolic function of microorganisms, the conventional method has room for improvement in terms of the stability and efficiency of the processing.

  Also, for example, when treating sewage in a sewage treatment facility, organic wastewater is first stored in a solid-liquid separation tank called a sedimentation basin, and raw sludge containing a large amount of organic solids is separated from its bottom. Therefore, it was necessary to treat this raw sludge separately.

  The present invention has been made in view of such circumstances, and is capable of effectively using raw sludge separated from organic wastewater, and a wastewater treatment apparatus and wastewater treatment capable of biologically treating organic wastewater sufficiently stably and efficiently. It aims to provide a method.

  The waste water treatment apparatus of the present invention uses granulated sludge formed by collecting and granulating microbial sludge, and is a first solid-liquid separation tank that separates organic waste water into raw sludge and treated water. And an aerobic tank that contains granule sludge and biologically treats the water to be treated under aerobic conditions, and a second solid that separates the biologically treated water that has been treated in the aerobic tank into separated water and separated sludge. Liquid separation tank, acid generation tank that ferments raw sludge to generate organic acid, granule generation tank that generates granular sludge from raw material liquid containing organic acid, and granules generated in the granule generation tank A first granule supply line for supplying sludge to the aerobic tank.

  In addition, the wastewater treatment apparatus of the present invention, as described below, decomposes nitrogen-containing compounds in addition to decomposing and removing organic compounds by biological treatment that combines treatment under aerobic conditions and treatment under anoxic conditions. It may also be possible.

  That is, the wastewater treatment apparatus of the present invention uses granule sludge formed by collecting and granulating microbial sludge, and is a third solid liquid that separates organic wastewater into raw sludge and treated water. An aerobic that contains a separation tank and granule sludge, reduces organic matter contained in the water to be treated under aerobic conditions, and generates nitrate nitrogen by oxidizing ammonia nitrogen contained in the water to be treated. A tank, an anaerobic tank in which a portion of the treated water in the aerobic tank and the granular sludge is supplied, and nitrogen gas contained in the treated water is reduced under anoxic conditions to generate nitrogen gas; A fourth solid-liquid separation tank that separates biologically treated water that has undergone treatment in an aerobic tank and an anaerobic tank into separated water and separated sludge; an acid generation tank that ferments raw sludge to produce an organic acid; Granule sludge is produced from acid-containing raw material liquid Comprising a granule production tank, the granular sludge generated in granules production tank and a second granule supply line for supplying the anoxic tank and / or aerobic tank, the for.

  In the wastewater treatment apparatus of the present invention, raw sludge separated from organic wastewater is fermented in an acid production tank to produce an organic acid. By using this raw material liquid containing an organic acid, aerobic granular sludge can be generated stably and efficiently. As described above, according to the present invention, it is possible to effectively use raw sludge that conventionally requires separate treatment.

  Moreover, in the waste water treatment apparatus of this invention, biological treatment can be performed stably and efficiently by utilizing granule sludge. Granule sludge is a pulverized sludge that is aggregated and granulated, and because it has excellent sedimentation properties, the sludge concentration in biological treatment tanks (aerobic tank and anoxic tank) can be maintained at a high level. . In addition, since the high sludge concentration can be maintained, the biological treatment tank can be significantly downsized, and the site area of the wastewater treatment facility can be saved and the equipment cost can be greatly reduced.

  In a wastewater treatment apparatus that performs biological treatment combining treatment under aerobic conditions and treatment under anaerobic conditions, an anaerobic tank that releases phosphorus accumulated in the cells of microbial sludge under anaerobic conditions, And a separation sludge return line for returning a part of the separated sludge discharged from the solid-liquid separation tank to the anaerobic tank, so that the anaerobic treated water that has been treated in the anaerobic tank is supplied to the anoxic tank. It is preferable that it is a simple structure.

  By adopting the above configuration, phosphorus-accumulating bacteria grow and the phosphorus-containing compound contained in the organic waste water can be removed. In this case, from the viewpoint of further improving the processing efficiency of the phosphorus-containing compound by the phosphorus accumulating bacteria, it is preferable to further include an organic acid supply line that supplies a part of the organic acid generated in the acid generation tank to the anaerobic tank. From the same viewpoint, it is preferable that the line for discharging the water to be treated from the third solid-liquid separation tank is connected to the anoxic tank.

  Further, from the viewpoint of maintaining a higher sludge concentration in the biological treatment tank, the aerobic tank preferably includes granule outflow prevention means for preventing the granular sludge in the tank from flowing out of the tank. From the same viewpoint, it is preferable that the waste water treatment apparatus of the present invention further includes granule collecting means for collecting the granular sludge that has flowed out from the aerobic tank together with the biologically treated water and returning it to the aerobic tank.

  The wastewater treatment method of the present invention uses granular sludge formed by microbial sludge being aggregated and granulated, a solid-liquid separation step for separating organic wastewater into raw sludge and treated water, The water to be treated is treated with an acid generation process for fermenting sludge to obtain an organic acid, a granule generation process for obtaining granule sludge from a raw material liquid containing organic acid, and a granule sludge obtained through the granule generation process. An aerobic treatment step for biologically treating under aerobic conditions.

  In the wastewater treatment method of the present invention, organic sludge is produced by fermenting raw sludge separated from organic wastewater. By using this raw material liquid containing an organic acid, aerobic granular sludge can be generated stably and efficiently. As described above, according to the present invention, it is possible to effectively use raw sludge that conventionally requires separate treatment.

  In the wastewater treatment method of the present invention, the sludge concentration in the biological treatment tank can be maintained at a high concentration by using granule sludge, so that the biological treatment can be performed stably and efficiently. In addition, since the high sludge concentration can be maintained, the biological treatment tank can be greatly reduced in size, and the site area of the wastewater treatment facility can be saved and the equipment cost can be greatly reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the raw sludge isolate | separated from organic waste water can be used effectively, and the waste water treatment apparatus and waste water treatment method which can carry out biological treatment of organic waste water fully stably and efficiently can be provided.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In each figure, the same symbols are attached to the same elements, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing a wastewater treatment apparatus according to the first embodiment of the present invention, which is employed in, for example, a sewage treatment facility.

  As shown in FIG. 1, the waste water treatment apparatus 100 is an apparatus that performs a process including an aerobic process by aeration. The wastewater treatment apparatus 100 includes a granule sludge generation apparatus 10 together with a first sedimentation tank 1, a biological treatment tank (aerobic tank) 2 </ b> A, and a final sedimentation tank 3. Here, in this embodiment, the first sedimentation tank 1 corresponds to a first solid-liquid separation tank, and the final sedimentation tank 3 corresponds to a second solid-liquid separation tank.

  In the wastewater treatment apparatus 100, coarse wood chips and the like are removed by a coarse screen of a sewage treatment facility, and solids having a relatively large particle size are settled and separated in a sand basin, such as cloth, empty cans, vinyls, etc. The sewage is removed with a screen, and the inflow sewage (organic waste water) pumped up from the pump well is first introduced into the settling tank 1 through the line L1.

  The inflowing sewage is introduced into the first sedimentation basin 1 from the line L1, and separated into raw sludge and other supernatant water that settles to the bottom of the first sedimentation basin 1 by gravity sedimentation. The raw sludge settled here is scraped to the sludge reservoir 1a by a sludge scraper (not shown) and sent to the granule sludge generation apparatus 10 through the line L11. Although the details will be described later, the granule sludge generating apparatus 10 generates organic acids (for example, acetic acid, propionic acid, butyric acid) by acid fermentation of raw sludge, and uses an organic acid solution containing this as a raw material liquid. It is a device that produces granular sludge. The aerobic granule sludge produced | generated with this granule sludge production | generation apparatus 10 is introduce | transduced in the biological treatment tank 2A through line (1st granule supply line) L19A.

  The biological treatment tank 2A is an aeration tank for aerobically treating the supernatant water (treated water) introduced from the line L2 under aerobic conditions, and an aeration device 2d provided in the tank, And a blower 2e for supplying air to the air diffuser 2d. The biological treatment tank 2A accommodates the aerobic granular sludge from the line L19A, and aerobic treatment with the granular sludge is performed on the water to be treated. The biologically treated water that has been subjected to the aerobic treatment is sent to the final sedimentation basin 3 via the line L3.

  On the base end side of the line L3 connected to the biological treatment tank 2A, a filter (granule outflow prevention means) 2f for preventing the granular sludge from flowing out of the tank together with the biological treatment water is installed. In addition, what is necessary is just to set the opening size of the filter 2f suitably according to the particle size (about 0.5 millimeters-about several millimeters) of the granular sludge to be used and the particle size of activated sludge (except granule sludge).

  The biologically treated water sent to the final settling basin 3 via the line L3 is discharged through the line L5 after settling and separating the suspended activated sludge, and after the tertiary treatment and sterilization treatment are performed in an unillustrated facility, Released into rivers. The sedimented activated sludge is scraped to the sludge reservoir 3a by a sludge scraper (not shown) and discharged from the line L6. A part of the sludge is introduced into the biological treatment tank 2A through the line (separated sludge return line) L7. The rest is sent to a sludge treatment tank (not shown) for processing.

  The granule sludge generation apparatus 10 includes a raw sludge storage tank 11, an acid generation tank 12, and a solid-liquid separation tank 13 in this order via a line L12 and a line L13, and a line on the supernatant water side of the solid-liquid separation tank 13. A batch-type granule production tank 20 is provided via L17. The granule generation tank 20 is connected to the biological treatment tank 2A via the line L19A.

  The raw sludge storage tank 11 is a tank for temporarily storing the raw sludge introduced through the line L11. The raw sludge storage tank 11 includes a sludge stirrer 11a in the tank. The raw sludge stirred by the sludge stirrer 11a and having a sufficiently uniform sludge concentration is transferred to the acid generation tank 12 by a pump P1 disposed in the line L12.

  The acid production tank 12 produces an organic acid by subjecting organic matter in raw sludge supplied through the line L12 to acid fermentation with acid producing bacteria. The acid generation tank 12 includes a stirrer 12a that stirs the to-be-fermented processing liquid staying in the tank. Moreover, although not shown in FIG. 1, the acid production tank 12 adds an acid or an alkali to the pH sensor and ORP measurement sensor which each measure the pH of a to-be-fermented process liquid, and an oxidation reduction potential, and a to-be-fermented process liquid. A pH adjusting device that adjusts the pH of the liquid to be fermented and an air supply device that adjusts the oxidation-reduction potential of the liquid to be fermented are provided.

  The solid-liquid separation tank 13 is a precipitation tank that separates the fermentation treatment liquid produced in the acid production tank 12 into an organic acid solution and acid-producing bacterial cell-containing sludge containing acid-producing bacterial cells. In addition, it can replace with this precipitation tank and can use solid-liquid separation apparatuses, such as a membrane separation tank (membrane separation apparatus), for example.

  The organic acid solution (raw material liquid) separated in the solid-liquid separation tank 13 is supplied to the batch-type granule production tank 20 through a line L17 in which a valve V1 is arranged on the way. On the other hand, the precipitated acid-producing bacterial cell-containing sludge is discharged from the line L15, a part of which is introduced into the acid generation tank 12 through the line L14 in which the pump P2 is disposed in the middle, and the rest is, for example, dehydration-incineration Provided for processing.

  The batch-type granule production tank 20 is a tank for producing granule sludge obtained by using an organic acid solution supplied through a line L17 as a raw material liquid and collecting microbial sludge and granulating it. A line L7a for introducing a part of the returned sludge is connected to the granule generation tank 20. The line L7a is branched from the line L7, and a valve V4 is disposed in the middle.

  The granule production tank 20 is an airlift type semi-batch reactor (SBR), and gradually forms granules from microbial sludge by repeating a predetermined basic cycle. In the following description of the granule generation tank 20, the activated sludge including microbial sludge and granule sludge is also referred to.

  2-5 is a figure which shows the state in each operation of the granule production | generation process of the granule production | generation tank 20, respectively. As shown in FIGS. 2-5, the granule production | generation tank 20 is equipped with the cylindrical tank 21 for accommodating a liquid.

  A line L19A for supplying granular sludge generated in the tank 21 to the biological treatment tank 2A is connected to the bottom of the tank 21. On the other hand, a line L <b> 18 for discharging the treated water W in the tank 21 is connected to the side wall portion of the tank 21. A valve V2 and a valve V3 are provided in the middle of the line L18 and the line L19A, respectively.

  Further, an inner cylinder 22 is disposed in the tank 21, and an aeration bulb 23 is provided at the lower portion of the inner cylinder 22 as an aeration means for aeration of the tank 21. A blower 25 is connected to the air diffuser 23, and the air from the blower 25 is blown into the air diffuser 23 to be diffused into the tank 21.

  In the granule production tank 20 configured as described above, the particle size of the granule sludge gradually increases as the organic acid is engulfed and propagated by the microbial sludge under aerobic conditions.

  In the present embodiment, the inner cylinder 22 is used in order to circulate the tank 21 efficiently. However, this shape is not limited to the present embodiment, and the shape is such that the tank 21 is circulated efficiently. Anything is acceptable.

  Next, a method for treating organic wastewater by the wastewater treatment apparatus 100 according to the present embodiment will be described.

  First, inflow sewage is first separated into raw sludge and treated water in the settling basin 1 (solid-liquid separation step). Water to be treated is introduced into the biological treatment tank 2A and biologically treated under aerobic conditions (aerobic treatment step). In this biological treatment tank 2A, granule sludge obtained through a granule generation step described later is accommodated.

  Biologically treated water is introduced into the final sedimentation basin 3 from the biological treatment tank 2A through the line L3, and the biologically treated water is solid-liquid separated into separated water and separated sludge in the final sedimentation basin 3. After the sterilization process is performed on the separated water discharged from the final sedimentation tank 3 through the line L5, the separated water is discharged into a river or the like. A part of the separated sludge discharged through the line L6 is returned to the biological treatment tank 2A through the line L7, and the remaining separated sludge (surplus sludge) is discharged out of the system.

  On the other hand, the raw sludge first separated in the settling basin 1 is introduced into the granule sludge generating apparatus 10. Raw sludge stirred in the raw sludge storage tank 11 is introduced into the acid generation tank 12 and the sludge concentration is sufficiently uniform, and the organic matter in the raw sludge is acid-fermented by acid-producing bacteria to produce an organic acid (acid generation step). ). The oxidation-reduction potential of the to-be-fermented processing solution in the acid production tank 12 is preferably about −300 to −200 mV, and the pH is preferably about 4 to 6.5. In addition, the organic acid solution with an organic substance density | concentration of about 100-3000 mass ppm can be obtained by implementing the fermentation process for the period of about 1-4 days.

  The fermentation treatment liquid obtained through the acid production step is separated in the solid-liquid separation tank 13, and the obtained organic acid solution is introduced into the granule production tank 20. In the granule production | generation tank 20, an organic acid solution is used as a raw material liquid, and granule sludge is produced | generated (granule production | generation process). The generated granular sludge is supplied to the biological treatment tank 2A via the line L19A. The supply of granule sludge to the biological treatment tank 2A may be performed when the granule sludge is reduced in size by crushing or the like and flows out of the biological treatment tank 2A, so that the granule sludge concentration in the tank is lowered. Alternatively, it may be performed continuously.

  As shown in FIG. 6, the granule generation process is performed by a semi-batch process that repeats the basic cycle including the injection process S1, the air diffusion process S2, the stationary process S3, and the discharge process S4. Hereinafter, each step will be described.

  In the injection step S1, the return sludge containing the organic acid solution and the microbial sludge is introduced into the tank 21 as shown in FIG. FIG. 2 shows a state in which the organic acid solution and the returned sludge are again injected from each line (line L17, line L7a) after performing a basic period (described later) of the granule generation process at least once. The hatching of the activated sludge G indicates a state where the microbial sludge G1 and the granulated granule G2 are precipitated and deposited.

  Valves V1 and V4 arranged in the middle of the line L17 and the line L7a are opened, and both fluids are introduced into the tank 21. In addition, from the viewpoint of efficiently generating granules which are aggregates of microbial sludge, it is preferable to inject return sludge containing microbial sludge from the line L7a into the tank 21, but the microbial sludge is sufficiently contained in the tank 21. Returning sludge does not necessarily have to be injected when it is growing.

  In the subsequent air diffusion step S2, as shown in FIG. 3, the blower 25 is driven to blow air to the air diffuser bulb 23, and the liquid in the tank 21 is aerated by being diffused from the air diffuser bulb 23. From the viewpoint of efficiently generating granules G2, it is preferable to adjust the amount of air diffused so that the circulation flow rate in the tank 21 is about 0.5 to 10 m / min. The microbial sludge G1 gathers in the process of flowing at a circulation flow rate in the above range to form small granules and grows gradually.

  In the stationary step S3 after the air diffusing step S2, as shown in FIG. 4, the blower 25 is stopped and aeration is stopped and left standing. Thereby, the solid substance (activated sludge G) floating in the liquid in the tank 21 is settled, and the activated sludge G is deposited on the bottom of the tank 21. Subsequently, in the discharge step S4, as shown in FIG. 5, the treated water W, which is a supernatant, is discharged from the line L18.

  The basic cycle consisting of the injection step S1, the air diffusion step S2, the stationary step S3, and the discharge step S4 is repeated. By repeating the basic period, when aeration is performed in the aeration step S2, the microbial sludge G1 is self-granulated to generate granules G2 having a large particle size. The particle size of the granules G2 to be produced varies depending on the processing conditions, but is usually about 0.5 mm to several mm.

  Of the injection step S1, the diffusion step S2, the stationary step S3, and the discharge step S4, the time required for the injection step S1 and the discharge step S4 depends on the scale of the apparatus (the internal volume of the tank 21, etc.). On the other hand, the time required for the air diffusion process S2 and the stationary process S3 is less dependent on the scale of the apparatus. For example, the aeration time in the air diffusion step S2 may be about several hours to about 24 hours, and the standing time in the standing step S3 may be about several tens of minutes to several hours.

  In the granule generation process that repeats the basic period, the organic acid solution is supplied through the line L17 in the injection process S1. Therefore, the organic acid contained in the organic acid solution is intermittently given to the microbial sludge G1. Therefore, for the microbial sludge G1, a state in which nutrition is abundant (satiated state) and a state in which nutrition is insufficient (starvation state) are repeated. Thus, when it becomes satiety after going through a starvation state, the microbial sludge G1 ingests more nutrients, so that an extracellular polymer is likely to be formed, and the microbial sludge G1 is likely to self-granulate.

  According to the first embodiment, since granular sludge in which microbial sludge is densely gathered is used in the biological treatment tank 2A, the sludge concentration in the biological treatment tank 2A is higher than that in the case where normal activated sludge is used. Concentration can be maintained. Therefore, the decomposition treatment efficiency of the organic matter (BOD component) in the organic waste water can be remarkably improved. As a result, the volume of the biological treatment tank 2A can be significantly reduced.

(Second Embodiment)
FIG. 7 is a schematic configuration diagram showing a wastewater treatment apparatus according to the second embodiment of the present invention. The wastewater treatment apparatus 200 shown in the figure is different from the wastewater treatment apparatus 100 of the first embodiment in that it is an apparatus that performs advanced treatment including biological denitrification and biological dephosphorization on sewage. The waste water treatment apparatus 200 includes a granule sludge generation apparatus 10 together with a first sedimentation tank 1, a biological treatment tank 2 </ b> B, and a final sedimentation tank 3. In the present embodiment, the first sedimentation tank 1 corresponds to a third solid-liquid separation tank, and the final sedimentation tank 3 corresponds to a fourth solid-liquid separation tank.

More specifically, the waste water treatment apparatus 200 is different from the waste water treatment apparatus 100 of the first embodiment in the following points (1) to (5).
(1) The biological treatment tank 2B includes an anaerobic tank 2a, an oxygen-free tank 2b, and an aerobic tank 2c in this order, and performs biological treatment by an activated sludge method called A2O method. The treatment liquid that has undergone the treatment in the anaerobic tank 2a is sent to the anaerobic tank 2b, and the treatment liquid that has undergone the treatment in the anaerobic tank 2b is sent to the aerobic tank 2c.
(2) The treated water from the first sedimentation tank 1 is supplied to the anoxic tank 2b through the line L2.
(3) A line L4 is provided for returning a part of the processing liquid and granule sludge in the aerobic tank 2c to the anoxic tank 2b.
(4) A line (organic acid supply line) L16 for supplying a part of the organic acid solution to the anaerobic tank 2a is provided.
(5) A line (second granule supply line) L19B for supplying the granular sludge generated in the granule generation tank 20 to the anoxic tank 2b and / or the aerobic tank 2c is provided.

  By adopting the configuration of (1) above, it is possible to perform advanced treatment including biological denitrification and biological dephosphorization on sewage.

By adopting the configuration of (2) above, nitrate nitrogen (NO ₃ ⁻ −N) is converted to nitrogen gas by denitrifying bacteria in the anoxic tank 2b in the presence of organic matter (BOD component) contained in the water to be treated. To reduce nitrogen from the water to be treated. In addition, when the organic substance density | concentration of to-be-processed water is high, or when the fluctuation | variation of to-be-processed water amount is small, you may introduce the to-be-processed water from the sedimentation tank 1 into the anaerobic tank 2a first, or the anaerobic tank 2a and anaerobic oxygen You may divide and introduce into both tanks 2b suitably.

By adopting the above configuration (3), nitrate nitrogen produced in the aerobic tank 2c _(NO ³ - -N) can be supplied to the anoxic tank 2b. Here, nitrate nitrogen is obtained by oxidizing ammonia nitrogen (NH ₄ ⁺ -N) mainly in water to be treated by nitrifying bacteria in the aerobic tank 2c.

  By adopting the configuration of (4) above, an organic acid can be supplied into the anaerobic tank 2a, and in the anaerobic tank 2a, organic matter is returned to the microbial cells of the returned sludge introduced via the line L7. At the same time as the acid is taken in, the microbial cells efficiently release phosphorus. In addition, the phosphorus accumulating bacteria exposed under anaerobic conditions in the anaerobic tank 2a pass through the anaerobic tank 2b and the aerobic tank 2c in order to proliferate the phosphorus accumulating bacteria preferentially. Phosphorus treatment is promoted.

  By adopting the configuration of (5) above, the granular sludge generated in the granule generation tank 20 can be appropriately supplied to the anoxic tank 2b and / or the aerobic tank 2c according to the operating conditions.

  The oxidation-reduction potential in the anaerobic tank 2a is preferably maintained at about -450 to -150 mV from the viewpoint of maintaining an anaerobic state suitable for phosphorus release from the microbial cells. The oxidation-reduction potential in the anoxic tank 2b is preferably maintained at about −300 to −100 mV from the viewpoint of promoting the denitrification reaction of the water to be treated.

  According to the second embodiment, the granular sludge in which microbial sludge is densely gathered is used in the anoxic tank 2b and the aerobic tank 2c, so that the sludge in both tanks is compared with the case where normal activated sludge is used. The concentration can be maintained at a high concentration. Therefore, in the anaerobic tank 2b, the denitrification reaction for converting nitrate nitrogen to nitrogen gas is promoted, and in the aerobic tank 2c, the nitrification reaction and organic matter (BOD) for converting ammonia nitrogen to nitrate nitrogen are promoted. The decomposition process of the component) is promoted. As a result, the volume of the biological treatment tank 2B can be greatly reduced. In particular, by increasing the speed of the nitrification reaction in the aerobic tank 2c that generally requires a large volume, the volume of the aerobic tank 2c can be greatly reduced.

  As described above, according to the first and second embodiments described above, the aerobic granule sludge can be stably and efficiently generated in the granule generation tank 20 by using the organic acid solution as the raw material liquid. . By using the granule sludge generated in the granule generation tank 20 in the biological treatment tanks 2A and 2B, the organic waste water can be biologically treated sufficiently stably and efficiently.

  When producing aerobic granule sludge, the organic matter concentration (BOD) of the raw material liquid is preferably about 200 to 1000 mg / L. According to this embodiment, the organic matter concentration is obtained by fermenting raw sludge. A range of organic acid solutions can be easily obtained. Note that normal sewage has a low organic substance concentration of about 50 to 200 mg / L and a large fluctuation, so that it is difficult to stably and efficiently generate aerobic granular sludge.

  Moreover, according to the said embodiment, the raw sludge isolate | separated by the sedimentation tank 1 initially can be used effectively as a raw material of granule sludge. Thereby, there exists an advantage that the sludge discharged | emitted from the said waste water treatment apparatus can be reduced.

  As mentioned above, although embodiment of this invention was described, it is not limited to the said embodiment of this invention, The following may be sufficient.

  The wastewater treatment apparatus according to the above embodiment includes a raw sludge storage tank 11 that stores the raw sludge separated in the first sedimentation basin 1, but does not install this raw sludge storage tank 11, and the raw sludge from the line L11. May be directly introduced into the acid generation tank 12. Moreover, when the sludge density | concentration of the raw sludge introduced into the acid production tank 12 is low, a raw sludge concentration tank is installed, and the concentrated sludge concentrated with the said concentration tank is introduced into the raw sludge storage tank 11 or the acid production tank 12 May be.

  Moreover, in the said embodiment, although it was set as the structure which introduce | transduces return sludge to the granule production tank 20 through the line L7a, since microorganisms sludge should just be supplied to the granule production tank 20, the organism transferred by the line L3 The treatment liquid, surplus sludge discharged from the line L6 or acid-producing cell-containing sludge discharged from the line L15 may be introduced into the granule generation tank 20. Further, when the organic acid solution contains sufficient microbial sludge, the microbial sludge does not have to be supplied to the granule generation tank 20.

  Furthermore, in the said embodiment, although the filter 2f was illustrated as a means to prevent a granular sludge from flowing out from biological treatment tank 2A, 2B, instead of this filter 2f, biological treatment from biological treatment tank 2A, 2B. You may provide the granule collection | recovery means which collect | recovers the granule sludge which flowed out with water. FIG. 8 is a schematic configuration diagram showing an example of the granule collecting means. The granule recovery means shown in the figure is a small granule separation tank 2g provided in the middle of the line L3 and the recovered granule sludge into a biological treatment tank (aerobic tank and / or anoxic tank). And a granule return line L2g for return.

  Further, although the activated sludge method (O method) is exemplified in the first embodiment and the biological denitrification / dephosphorization (A2O method) is exemplified in the second embodiment, anaerobic treatment and aerobic treatment are performed. The present invention may be applied to (AO method). Furthermore, in the said 2nd Embodiment, although the biological treatment tank 2B provided with the anaerobic tank 2a, the anaerobic tank 2b, and the aerobic tank 2c each was illustrated, in order to remove a nitrogen containing compound and a phosphorus containing compound more highly. Further, a series of anaerobic tanks and aerobic tanks may be added after the aerobic tank 2c. In this case, it is preferable to introduce the granular sludge generated in the granule generation tank 20 into these anaerobic tank and aerobic tank.

1 is a schematic configuration diagram illustrating a wastewater treatment apparatus according to a first embodiment of the present invention. It is a figure which shows the state in the injection process of a granule production tank. It is a figure which shows the state in the air diffusion process of a granule production tank. It is a figure which shows the state in the stationary process of a granule production tank. It is a figure which shows the state in the discharge process of a granule production tank. It is a flowchart which shows the basic period of a granule production | generation process. It is a schematic block diagram which shows the waste water treatment apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows an example of a granule collection | recovery means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... First sedimentation basin (1st, 3rd solid-liquid separation tank), 2A ... Biological treatment tank (aerobic tank), 2B ... Biological treatment tank, 2a ... Anaerobic tank, 2b ... Anoxic tank, 2c ... Aerobic Tank, 2f ... filter (granule outflow prevention means), 2g ... granule separation tank (granule recovery means), 3 ... final sedimentation tank (second and fourth solid-liquid separation tank), 12 ... acid generation tank, DESCRIPTION OF SYMBOLS 20 ... Granule production tank, 100,200 ... Waste water treatment apparatus, L2g ... Granule return line (granule recovery means), L7 ... Separation sludge return line, L16 ... Organic acid supply line, L19A ... First granule supply Line, L19B ... Second granule supply line.

Claims (8)

A wastewater treatment device that uses granulated sludge that is formed by granulating microbial sludge.
A first solid-liquid separation tank for separating organic wastewater into raw sludge and treated water;
An aerobic tank for containing the granular sludge and biologically treating the treated water under aerobic conditions;
A second solid-liquid separation tank that separates biologically treated water that has been treated in the aerobic tank into separated water and separated sludge;
An acid production tank for fermenting the raw sludge to produce an organic acid;
A granule production tank for producing the granule sludge from the raw material liquid containing the organic acid;
A first granule supply line for supplying the granule sludge generated in the granule generation tank to the aerobic tank;
A wastewater treatment apparatus comprising: A wastewater treatment device that uses granulated sludge that is formed by granulating microbial sludge.
A third solid-liquid separation tank that separates organic wastewater into raw sludge and treated water;
An aerobic tank that contains the granular sludge, reduces organic matter contained in the water to be treated under aerobic conditions, and generates nitrate nitrogen by oxidizing ammonia nitrogen contained in the water to be treated; ,
An anaerobic tank in which a part of the treated water in the aerobic tank and the granular sludge is supplied, and generates nitrogen gas by reducing nitrate nitrogen contained in the treated water under anoxic conditions;
A fourth solid-liquid separation tank that separates the biologically treated water that has been treated in the aerobic tank and the oxygen-free tank into separated water and separated sludge;
An acid production tank for fermenting the raw sludge to produce an organic acid;
A granule production tank for producing the granule sludge from the raw material liquid containing the organic acid;
A second granule supply line for supplying the granule sludge generated in the granule generation tank to the anoxic tank and / or the aerobic tank;
A wastewater treatment apparatus comprising:   An anaerobic tank for releasing phosphorus accumulated in the microbial sludge cells under anaerobic conditions; a separation sludge return line for returning a part of the separated sludge discharged from the fourth solid-liquid separation tank to the anaerobic tank; The wastewater treatment apparatus according to claim 2, further comprising anaerobic treated water that has been treated in the anaerobic tank and is supplied to the anaerobic tank.   The wastewater treatment apparatus according to claim 3, further comprising an organic acid supply line for supplying a part of the organic acid generated in the acid generation tank to the anaerobic tank.   The waste water treatment apparatus according to any one of claims 2 to 4, wherein a line for discharging the water to be treated from the third solid-liquid separation tank is connected to the anoxic tank. .   The said aerobic tank is equipped with the granule outflow prevention means which prevents that the granular sludge in a tank flows out of a tank, The waste water treatment as described in any one of Claims 1-5 characterized by the above-mentioned. apparatus.   The granule sludge which collected the granular sludge which flowed out with the biological treatment water from the aerobic tank is further provided, The granule recovery means which returns to the aerobic tank is provided, The any one of Claims 1-5 characterized by the above-mentioned. The waste water treatment apparatus as described in the item. It is a wastewater treatment method using granule sludge formed by aggregation and granulation of microbial sludge,
A solid-liquid separation process for separating organic wastewater into raw sludge and treated water;
An acid generation step of fermenting the raw sludge to obtain an organic acid;
A granule producing step for obtaining the granule sludge from the raw material liquid containing the organic acid;
An aerobic treatment step of biologically treating the treated water under aerobic conditions with the granule sludge obtained through the granule generation step;
A wastewater treatment method comprising:

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