JP5194484B2 - Biological treatment apparatus and biological treatment method for water containing organic matter - Google Patents

Description

  The present invention relates to a biological treatment apparatus and biological treatment method for treating organic substance-containing water by an activated sludge method, and in particular, a multistage biological treatment apparatus and biological treatment method in which two or more biological treatment tanks are connected in series. About.

  Biological treatment of organic matter-containing water is excellent in economic efficiency because it requires less energy than physicochemical treatment. Biological treatment of organic matter-containing water is broadly divided into aerobic treatment and anaerobic treatment. The anaerobic treatment requires less energy than the aerobic treatment, and the amount of surplus sludge generated by converting organic matter into microorganisms is also small. For this reason, anaerobic treatment has the advantage of being more economical than aerobic treatment, but the range and conditions of applicable organic matter-containing water are narrow.

  On the other hand, aerobic treatment can be applied to water containing organic matter with various properties compared to anaerobic treatment, and it is easy to maintain and can provide treated water with good water quality. Air treatment is widely used. However, in the aerobic treatment represented by the activated sludge method, 20 to 30% by mass of the BOD component (organic matter represented by biochemical oxygen consumption) contained in the organic matter-containing water introduced into the biological treatment tank is It is used for the growth of bacteria that make up activated sludge. Bacteria proliferated using the BOD component as a substrate are discharged as excess sludge. Therefore, a large amount of excess sludge is generated in the normal activated sludge method, and it is necessary to treat the excess sludge.

  Moreover, since it is necessary to supply oxygen to a biological treatment tank in an aerobic process, the energy which drives the aeration apparatus which supplies oxygen is required. Furthermore, since the load of the biological treatment tank is lower in the aerobic treatment than in the anaerobic treatment, a larger biological treatment tank is required. The amount of surplus sludge generated in the aerobic treatment, the amount of energy for aeration, and the volume of the biological treatment tank increase as the BOD concentration of the organic substance-containing water increases, and the treatment cost increases.

  In order to solve the above aerobic treatment problems, for example, sludge volume reduction technology that reduces the amount of excess sludge generated by solubilizing excess sludge with an oxidizing agent or heat and then performing biological digestion treatment. Has been developed. In addition, a biofilm method has been developed to increase the microbial concentration in the biological treatment tank by adding a carrier for holding microorganisms to the biological treatment tank to reduce the tank volume.

  The above-described prior art is intended to individually solve the problems in aerobic biological treatment. For example, when sludge is solubilized and volume-reduced, the load on the biological treatment tank increases, leading to an increase in the size of the biological treatment tank. In the biofilm method in which a carrier is added to a biological treatment tank, the BOD load can be increased, but the generation of excess sludge is greater than that in a normal activated sludge method.

In contrast to these conventional techniques, a multi-stage aerobic biological treatment method in which a plurality of biological treatment tanks are connected in series has been developed. In the multi-stage aerobic biological treatment method, for example, a first biological treatment tank and a second biological treatment tank are arranged in series, and the first biological treatment tank is arranged with a BOD component volumetric load of 1 kg-BOD / m ³ / day. With the above high load, the second biological treatment tank is operated with a low load of BOD component sludge load 1 kg-BOD / kg-VSS / day or less. Thus, by operating the first biological treatment tank with a high load, the microorganisms are grown logarithmically to grow dispersible bacteria. On the other hand, in the second biological treatment tank, by using predatory animals' predation of dispersible bacteria and microbial self-digestion, excess sludge is reduced and microbial community aggregation (flocculation) is advanced.

As described above, the multistage activated sludge method is intended to reduce the size of the biological treatment tank and reduce the volume of excess sludge. However, maintaining the conditions for proceeding with flocking while reducing the volume of sludge in the second biological treatment tank. Is not easy. For example, since most of the BOD components that are easily biodegradable in the first biological treatment tank are removed, the amount of organic matter required in the second biological treatment tank may be insufficient and flocking may not proceed. . In view of this, a technique has been proposed in which a part of the organic substance-containing water containing a large amount of the BOD component is directly introduced into the second biological treatment tank by bypassing the first biological treated water. (Patent Document 1).
Japanese Patent No. 3258600

  However, the present inventors have found that with the technique described in Patent Document 1, organic substances are likely to remain in the second treatment liquid flowing out from the second biological treatment tank. Thus, it is difficult to solve a plurality of problems in aerobic biological treatment at the same time. For this reason, as described above, in the aerobic process, the technical development tends to be performed for the purpose of improving each elemental technology individually (for example, only for sludge volume reduction or only for the purpose of increasing the load). There is.

  On the other hand, an object of the present invention is to solve the plurality of problems at the same time by adjusting an entire series of aerobic biological treatment operations. Specifically, the overall processing flow of the multi-stage activated sludge process was reviewed to simultaneously reduce the size of the treatment tank and reduce the sludge volume by improving the BOD volumetric load, while also preventing the deterioration of the quality of treated water An object is to provide a biological treatment apparatus.

  In the multistage biological treatment method, the inventor performs solid-liquid separation of the first treatment liquid flowing out from the first biological treatment tank without adding an inorganic flocculant, and then separating the separated liquid into the second biological treatment tank. The present invention was completed by finding that the above-mentioned problems can be achieved by aerobic biological treatment and biologically reducing the volume of separated sludge. Specifically, the present invention provides the following.

(1) A first biological treatment tank in which organic substance-containing water containing an organic substance is introduced to perform an aerobic treatment, and a first treatment liquid flowing out from the first biological treatment tank are introduced, and an inorganic flocculant is used. A solid-liquid separation means for solid-liquid separation of the first treatment liquid into a separation liquid and separated sludge in a floating separation tank, a second biological treatment tank in which the separation liquid is introduced and an aerobic treatment is performed, wherein the separation sludge biologically volume reduction means for volume reduction, only contains the volume reducing means, de the concentrated sludge is introduced digestive fluid flowing out from the hot aerobic digester by concentrating the digested slurry A concentrator for discharging the separated liquid, a concentrated sludge return path for returning the concentrated sludge to the high-temperature aerobic digestion tank, and a desorbed liquid return path for returning the desorbed liquid to the first biological treatment tank. And a biological treatment apparatus for water containing organic matter.
(2) The biological treatment apparatus for organic matter-containing water according to (1), wherein the second biological treatment tank is a carrier fluidized bed type.
(3) The biological treatment apparatus for organic matter-containing water according to (1), wherein the second biological treatment tank is a membrane activated sludge system.
(4 ) The organic treatment water biological treatment apparatus according to any one of (1) to ( 3 ), further including advanced treatment means for advanced treatment of the second treatment liquid flowing out of the second biological treatment tank.
( 5 ) Organic matter-containing water containing organic matter is treated aerobically in the first biological treatment tank, and the first treatment liquid flowing out of the first biological treatment tank is floated and separated without using an inorganic flocculant. Solid-liquid separation into separation liquid and separation sludge in the tank, the separation liquid is treated aerobically in the second biological treatment tank, digestion liquid flowing out from the high temperature aerobic digestion tank is introduced, concentrated and concentrated Sludge and desorbed liquid are discharged, the concentrated sludge is returned to the high-temperature aerobic digestion tank, the desorbed liquid is returned to the first biological treatment tank, and the separated sludge is biologically reduced. A method for biological treatment of water containing organic matter.
( 6 ) The biological treatment apparatus for organic matter-containing water according to ( 5 ), wherein the second biological treatment tank is a carrier fluidized bed type.
( 7 ) The biological treatment apparatus for organic matter-containing water according to ( 5 ), wherein the second biological treatment tank is a membrane activated sludge system.
( 8 ) The organic substance according to any one of ( 5 ) to ( 7 ), wherein an aerobic treatment is performed at a high load of BOD component volumetric load 2 kg-BOD / m ³ / day or more in the first biological treatment tank. Biological treatment method of contained water.

The first biological treatment tank is a treatment tank that performs an aerobic treatment with activated sludge, and removes most of the BOD components (for example, about 60% or more, especially about 70 to 80%) contained in the organic substance-containing water. In addition, the operation is performed so that the activated sludge grown using the BOD component as a substrate does not undergo self-digestion. Specifically, the first biological treatment tank may have a load of 2 to 20 kg-BOD / m ³ / day, particularly 4 to 15 kg-BOD / m ³ / day.

Oxygen is supplied to the first biological treatment tank so that the dissolved oxygen (DO) concentration is about 2 mg / L. The oxygen supply means is not limited, and an air diffuser may be installed in the tank to blow in air. However, when a high load (for example, 10 kg-BOD / m ³ / day or more) is applied, an ejector is used, or air Instead of pure oxygen, pure oxygen may be supplied.

  Although the type of the first biological treatment tank is not limited, it is preferable to add a carrier to form a biofilm type in order to stably hold the cells under high load conditions. Moreover, when making it a floating type, it is good to return the sludge isolate | separated by the solid-liquid separation means (1st solid-liquid separation means) into which the effluent from a 1st biological treatment tank is introduce | transduced. Other conditions such as pH and temperature may be the same as those of the normal activated sludge method.

The first biological treatment tank is connected to the solid-liquid separation means (first solid-liquid separation means), and the effluent (first treatment liquid) from the first biological treatment tank is used as the first solid-liquid separation means. Solid-liquid separation with. As the first solid-liquid separation means, an apparatus capable of solid-liquid separation without using a flocculant, particularly an inorganic flocculant, is used. The first treatment liquid contains dispersed microorganisms that are not flocked, and the sludge sedimentation property is, for example, 200 or more in SVI (Sludge Volume Index). In addition, SVI means the sedimentation volume (ml) per 1g of sludge, and is shown by Numerical formula 1. Moreover, in Formula _{30, in} SV30, it is a sedimentation volume (%) when sludge is left still for 30 minutes.
(Formula 1)
SVI = SV ₃₀ × 10 ⁴ / sludge concentration (MLSS)

  Since the coagulation sedimentation tank and the membrane separation apparatus are not necessarily suitable for solid-liquid separation of the biological treatment liquid having the above-described properties without using an inorganic flocculant, a floating separation tank is used as the first solid-liquid separation means. It is preferable to do. When flocculant floating separation is performed by adding a flocculant, an organic flocculant that is easily biodegradable, for example, chitosans or polyaspartate is used as the flocculant, and the addition amount is preferably about several to 50 mg / L.

  The first solid-liquid separation unit is connected to the second biological treatment tank and the volume reduction unit. The liquid (separated liquid) separated from the solid content by the first solid-liquid separation means is supplied to the second biological treatment tank, and the solid content separated from the liquid (separated sludge) is supplied to the volume reducing means. Reduce volume with volume reduction means.

  The separated sludge is obtained without adding an inorganic flocculant, and the bacteria constituting the separated sludge are dispersed cells that do not produce a polymer substance and are highly biodegradable. For this reason, by adopting a digestion tank as a volume reducing means, it is possible to reduce the volume of sludge by suppressing the energy consumption required for volume reduction of sludge using the metabolic reaction of living organisms. In order to increase the digestion rate, the separated sludge should be digested at a high temperature. If the separated sludge is concentrated and digested as necessary, the energy required to maintain the high temperature conditions can be reduced by utilizing the heat of reaction during digestion. . The separated sludge is preferably solubilized by an oxidizing agent, heating, mechanical destruction, etc., and supplied to the digester to increase digestion efficiency. The digester may be anaerobic, but the aerobic digester is easy to manage and promotes self-digestion of the separated sludge derived from dispersible bacteria, so that it can be suitably employed in the present invention.

  On the other hand, the separation liquid is processed in the second biological treatment tank. The second biological treatment tank is not subjected to bypass injection of raw water (organic matter-containing water) containing BOD, and the BOD concentration of the liquid introduced into the second biological treatment tank is lowered (for example, 500 mg / L or less) to separate the liquid. Can improve the water quality of the treatment liquid (second treatment liquid) obtained by being treated in the second biological treatment tank.

As the second biological treatment tank, a carrier fluidized bed type or membrane activated sludge system is adopted, and bacteria that assimilate mainly persistent substances flowing from the first biological treatment tank as substrates are used as dominant species. Hold. In the case where the second biological treatment tank is a carrier fluidized bed type, a carrier is added to the second biological treatment tank, and the organic load is made lower than that of the first biological treatment tank. The added amount of the carrier may be about 30% by volume to 70% by volume. The load of the second biological treatment tank may be set according to the organic substance concentration of the separation liquid and the target water quality, but is generally 2 kg-BOD / m ³ / day or less, particularly 1.5 kg-BOD / m ³ / day or less. Should be set within the range. The DO concentration, pH, and temperature conditions of the second biological treatment tank may be the same as those in the normal activated sludge method, and the oxygen supply method is not particularly limited.

  The membrane activated sludge system uses a separation membrane such as an ultrafiltration membrane and a microfiltration membrane for solid-liquid separation between treated water and activated sludge. A membrane immersion type in which a separation membrane is immersed in an aeration tank. And a non-membrane immersion type in which the mixed liquid in the aeration tank is solid-liquid separated by a membrane separator provided outside the aeration tank and the separated sludge is returned to the aeration tank. As the second biological treatment tank, a membrane type activated sludge type can be adopted instead of the above-described carrier fluidized bed type.

  The second treatment liquid flowing out of the second biological treatment tank is subjected to solid-liquid separation by the second solid-liquid separation means to obtain treated water. As the second solid-liquid separation means, a floating separation tank may be used when the second treatment liquid has poor sedimentation, and a coagulation sedimentation basin using an inorganic flocculant may be used when the coagulation is good. When the treated water is supplied to activated carbon, a membrane separation device, an ion exchange resin tower, etc. for the purpose of recovering and reusing the treated water, a coagulation flotation filtration device, a coagulation sedimentation filtration device, a membrane separation device, etc. are used. And advanced processing. The sludge separated by the second solid-liquid separation means may be supplied to the volume reduction means, but if the content of the inorganic flocculant is large (for example, 1,000 mg / L or more), the volume reduction means Do not supply.

  In the present invention, the BOD load can be increased and the volume of the treatment tank can be reduced by growing dispersible bacteria in the first biological treatment tank. In addition, the volume of dispersible bacteria that are not covered with polymer substances that are difficult to biodegrade is reduced, so that aerobic digestion is easy to proceed, the amount of energy required for volume reduction can be reduced, and excess sludge is reduced. By doing so, the disposal cost of surplus sludge can also be reduced. Thus, according to the present invention, it is possible to simultaneously solve a plurality of problems such as a reduction in the volume of the biological treatment tank and a reduction in the amount of excess sludge generated.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a biological treatment apparatus (hereinafter simply referred to as “treatment apparatus”) 1 of organic matter-containing water according to a first embodiment of the present invention. The treatment apparatus 1 is a two-stage activated sludge treatment apparatus in which two biological treatment tanks are arranged in series. The first biological treatment tank 11 and a first floating separation tank 21 as a first solid-liquid separation means. , A second biological treatment tank 12, a second floating separation tank 22 as a second solid-liquid separation means, and a volume reduction means 40.

  A raw water pipe 31 is connected to the first biological treatment tank 11, and organic matter-containing water is introduced into the first biological treatment tank 11 through the raw water pipe 31. The organic substance-containing water may have a higher organic substance concentration than the organic substance-containing water processed by the conventionally used activated sludge method. For example, the total organic substance (TOC) concentration is about 400 to 2,000 mg / L, and the BOD concentration is 1,000 to 1,000. It may be about 6,000 mg / L. This is because such organic-containing water having a relatively high organic concentration has a high processing cost in the activated sludge method according to the conventional method, but according to the present invention, an increase in the processing cost can be suppressed as described later.

  The first biological treatment tank 11 holds a high concentration of microbial cells and operates with a high load to grow dispersible bacteria. The preferable operating conditions of the first biological treatment tank 11 are as described above, and in this embodiment, a biofilm type in which the carrier 15 is added at an addition amount of about 30% by volume is used. The first biological treatment tank 11 is provided with an ejector 16 as an oxygen supply means to increase the dissolution efficiency of oxygen so that a DO concentration of 2 mg / L or more can be maintained even under high load conditions.

  The first biological treatment tank 11 is connected to the first floating separation tank 21 via the first treatment liquid pipe 32. The first flotation separation tank 21 is a pressurized flotation separation tank, which supplies a pressurized gas without using a flocculant and releases it to atmospheric pressure to float the solid content and separate it from the liquid.

  The first flotation separation tank 21 is connected to the second biological treatment tank 12 via a separation liquid pipe 33 and is connected to the digestion tank 14 of the volume reducing means 40 via a separation sludge pipe 41. In the middle of the separation sludge pipe 41, a coagulation separation sludge pipe 43 described later is connected, and a centrifugal concentrator 23 is further provided. The separated sludge pipe 41 may be branched and a part of the separated sludge may be returned to the first biological treatment tank 11 by connecting the branch destination to the first biological treatment tank 11.

  The digestion tank 14 is a high-temperature aerobic digestion tank having an air diffuser 18 as an oxygen supply means, and the separated sludge discharged from the first flotation separation tank 21 is concentrated by a centrifugal concentrator 23 to increase the sludge concentration. To the digester 14. The concentrated filtrate discharged by the concentration of the separated sludge is returned to the first biological treatment tank 11 from the concentrated filtrate pipe 42.

  The separated sludge concentrated by the centrifugal concentrator 23 is sent from the concentrated separated sludge pipe 47 to the digestion tank 14. By increasing the concentration of the sludge to be digested in this way, the amount of energy required for high-temperature digestion that digests the liquid in the digestion tank 14 can be reduced. If pure oxygen is blown into the digestion tank 14 from the diffusing tube 18, a temperature drop due to aeration can be prevented. In this embodiment, the ozone reaction tank 13 is provided in the middle of the concentrated and separated sludge tube 47 so that the concentrated separated sludge is solubilized with ozone and then digested. Thus, digestion efficiency can be improved by solubilizing the separated sludge. A digested sludge pipe 44 is connected to the digestion tank 14, and the digested sludge is appropriately discharged from the digested sludge pipe 44.

  The second biological treatment tank 12 is a carrier fluidized bed type in which the carrier 15 is added at an addition amount of about 50%, and an aeration pipe 17 is installed as an oxygen supply means. Preferred operating conditions for the second biological treatment tank 12 are as described above. The second biological treatment tank 12 is connected to the second floating separation tank 22 via the second treatment liquid pipe 34.

  The second flotation separation tank 22 is a flocculation levitation tank having a flocculant addition means (not shown). As the flocculant, the organic polymer described above is preferably used, and the addition amount is preferably about 1 to 50 mg / L, but is not limited thereto, and an inorganic flocculant may be used.

  The solid content (aggregated separation sludge) discharged from the second flotation separation tank 22 is discharged through the aggregation separation sludge pipe 43. In the present embodiment, the flocculated separation sludge pipe 43 is connected to the separated sludge pipe 41 so that the flocculated separation sludge is digested in the digestion tank 14. The agglomerated separation sludge contains a flocculant, but the amount generated is as small as 5 to 30% of the amount of the separated sludge discharged from the first floating separation tank 21, and the agglomerated separation sludge is supplied to the digestion tank 14. However, the coagulant is less likely to inhibit digestion, and the amount of excess sludge discharged from the entire biological treatment apparatus 1 can be reduced by reducing the volume of the coagulated and separated sludge.

  The liquid separated from the coagulation / separation sludge in the second flotation separation tank 22 is taken out as treated water. However, when it is reused as recovered water or the like, advanced treatment is performed. FIG. 2 is a schematic diagram of the biological treatment apparatus 2 according to the second embodiment of the present invention. In the biological treatment apparatus 2, the second solid-liquid separation means is configured as an advanced treatment means including a coagulation sedimentation basin 22A and a sand filtration device 22B. Coagulation sedimentation basin 22A and sand filtration device 22B are connected by connecting pipe 22C, and the coagulated and settled liquid is further clarified by sand filtration.

  In the biological treatment apparatus 2, a digested sludge concentrator 24 is provided at the subsequent stage of the digester tank 14, and digested sludge discharged from the digester tank 14 is supplied to the digested sludge concentrator 24 through the digested sludge pipe 44. The solid content concentrated by the digested sludge concentrator 24 is discharged from the concentrated digested sludge tube 45. The concentrated sludge pipe 45 is further connected to the digestion tank 14 to further digest the concentrated sludge and a part thereof may be discharged as excess sludge. The liquid (digestion / detachment liquid) is taken out from the digestion / detachment liquid tube 46. The digestion / desorption liquid pipe 46 is connected to the concentrated filtrate pipe 42, and the digestion / desorption liquid is used as the first biological treatment tank 11 with the digestion / desorption liquid pipe 46 and the concentrated filtrate pipe 42 as the desorption liquid return path. It is configured to be biologically processed.

  If comprised in this way, the moisture content can be reduced by discharging | emitting the sludge (excess sludge) which was the biological treatment residue in the digestion tank 14, and the inorganic component etc. were concentrated from the digestion tank 14, and concentrating. Therefore, the amount of excess sludge discharged from the entire biological treatment apparatus 2 can be further reduced.

  FIG. 3 is a schematic view of the biological treatment apparatus 3 according to the third embodiment of the present invention. In the biological treatment apparatus 3, the separated sludge pipe 41 and the aggregated separated sludge pipe 43 are connected to the sludge supply pipe 48, and the sludge supply pipe 48 is connected to the centrifugal concentrator 23. The separated sludge discharged from the first flotation separation tank 21 and the agglomerated separation sludge discharged from the second flotation separation tank 22 are concentrated by the centrifugal concentrator 23. The concentrated sludge concentrated by the centrifugal concentrator 23 is supplied to the digestion tank 14 through the concentrated separation sludge pipe 47 to reduce the volume.

  Excess sludge is appropriately discharged from the digestion tank 14. In this embodiment, the digested sludge is concentrated by the centrifugal concentrator 23 by connecting the digested sludge pipe 44 that draws the digested sludge from the digestion tank 14 to the sludge supply pipe 48. To do. Excess sludge is discharged from an excess sludge pipe 45 attached to the centrifugal concentrator 23. The concentrated filtrate discharged from the centrifugal concentrator 23 is sent to the first biological treatment tank 11 through the digestion / desorption liquid tube 46 (not shown).

  What is necessary is just to perform the sludge volume reduction process in the biological treatment apparatus 3 by a batch process. In the biological treatment apparatus 3, the concentration of the separated sludge supplied to the digestion tank 14 can be increased and the water content of the excess sludge discharged from the digestion tank 14 can be reduced by a single concentrator. For this reason, compared with the biological treatment apparatus 2, the quantity of the excess sludge generated from the whole apparatus with a simple apparatus can be reduced.

In the present invention, the BOD removal efficiency per treatment tank (BOD removal amount / treatment tank volume m ³ / day) is increased by applying a high load in the first biological treatment tank. When the first biological treatment tank is operated at a high load, since bacteria do not self-digest, the amount of excess sludge generated increases, but dispersible bacteria that do not flock grow. Such dispersible bacteria are not encapsulated in a polymer substance, so that they can be concentrated easily and can be easily reduced in volume by high-temperature digestion. In the present invention, dispersible bacteria are separated from the liquid without using a flocculant, and preferably concentrated to reduce the volume by high-temperature digestion, thereby reducing excess sludge while obtaining high BOD removal efficiency. Make it possible.

  Moreover, since the liquid component supplied to the second biological treatment tank is separated from the solid content by the first solid-liquid separation means, the BOD decomposition load in the second biological treatment tank is low. For this reason, in the second biological treatment tank, microorganisms that decompose organic substances other than BOD, for example, organic substances such as surfactants called hardly decomposable organic substances, are likely to grow and were treated in the second biological treatment tank. The quality of treated water is improved. Furthermore, by adding a carrier to the second biological treatment tank, a protozoan or the like having a slow growth rate can be held in the second biological treatment tank, and therefore, sludge volume reduction due to the predatory action of the protozoa can be achieved.

<Example>
Hereinafter, the present invention will be described in more detail based on examples. The organic substance-containing water used in the examples has a flow rate of 24 m ³ / day, BOD concentration of 2,000 mg / L, total nitrogen concentration of 300 mg / L, total phosphorus concentration of 25 mg / L, conductivity of 50 mg / m, pH of 8, temperature of 25 ° C., insoluble Concentration (SS) concentration was less than 1 mg / L.

  In the example, an experimental apparatus simulating the processing apparatus 1 shown in FIG. 1 was used. Each of the first biological treatment tank and the second biological treatment tank is a carrier-added fluidized bed type in which a polyurethane square carrier is added at a volume ratio of 40%. The specifications and processing conditions of other devices are described below.

[First biological treatment tank]
Volume; 4m ³
MLSS concentration: 5,000 mg / L
BOD tank load; 12 kg-BOD / m ³ / day HRT; 4 hours [second biological treatment tank]
Volume; 9m ³
MLSS concentration; 2500 mg / L
BOD tank load; 1 kg-BOD / m ³ / day HRT; 9 hours [the entire biological treatment tank including the first biological treatment tank and the second biological treatment tank]
Treated water volume: 24 m ³ / day

As a volume reduction means, a high-temperature aerobic digester was used, and the separated sludge sent from the first flotation separation tank and the second flotation separation tank was concentrated by a centrifugal concentrator and supplied to the digestion tank. The concentrated sludge supplied to the digestion tank was solubilized by ozone treatment in an ozone reaction tank. The conditions for the solubilization treatment and the volume reduction treatment by the volume reduction means are as follows.
[Digestion tank]
Volume; 4.8m ³
[Ozone reaction tank]
Volume; 4.8m ³
Ozone supply amount: 0.6 kg / day

In the first levitation separation tank and the second levitation separation tank, pressure levitation was performed. Details are described below.
[First floating separation tank]
Volume: 0.5m ³
Flocculant; no addition [first flotation separation tank]
Volume: 0.5m ³
Flocculant ； Yes

  In Examples, the sludge amount generated from each of the first biological treatment tank and the second biological treatment tank is 12 kg and 0.9 kg, respectively, and the surplus sludge amount generated from the whole biological treatment apparatus is per day. 1 kg. Further, the water quality (TOC concentration) of the separated liquid that has flowed out of the first biological treatment tank and solid-liquid separated in the first floating separation tank is 150 mg / L, and flows out of the second biological treatment tank, The quality of the treated water (TOC concentration) separated into solid and liquid in the floating separation tank was 5 mg / L.

<Comparative example 1>
In Comparative Example 1, an experimental apparatus simulating the biological treatment apparatus 4 shown in FIG. 4 was used. In the biological treatment apparatus 4, the bypass pipe 30 branched from the raw water pipe 31 is connected to the second biological treatment tank 12, and a part of the raw water bypasses the first biological treatment tank 11 and becomes the second biological treatment tank 12. It is to be added. Further, the first solid-liquid separation means 21 ′ and the second solid-liquid separation means 22 ″ are coagulation sedimentation basins, and a coagulant (polyaluminum chloride, hereinafter “PAC”) stored in the coagulant storage tank 20. Was added. Details are described below.

[Second biological treatment apparatus]
Raw water injection amount: 5 m ³ / day [first solid-liquid separation means]
Volume: 0.5m ³
Flocculant (PAC) addition amount: 500 mg / L
[Second solid-liquid separation means]
Volume: 0.5m ³
Flocculant (PAC) addition amount: 100 mg / L

  In Comparative Example 1, the test was performed under the same conditions as in Examples except that raw water was bypassed and the first treatment liquid and the second treatment liquid were solid-liquid separated using a flocculant. As a result, the amount of sludge generated from the first biological treatment tank and the second biological treatment tank is 9.8 kg and 3.1 kg, respectively, and the amount of excess sludge generated from the entire biological treatment apparatus is 1 day. 2.3 kg per unit. In addition, the water quality (TOC concentration) of the separated liquid that has flowed out of the first biological treatment tank and solid-liquid separated by the first solid-liquid separation means is 120 mg / L, and has flowed out of the second biological treatment tank, The water quality (TOC concentration) of the treated water that was solid-liquid separated by the solid-liquid separation means 2 was 20 mg / L.

Table 1 shows the results of Examples and Comparative Example 1.

  As shown in Table 1, according to the present invention, it was shown that the amount of sludge generated from the entire treatment apparatus is small and the quality of the treated water is good according to the present invention.

<Comparative example 2>
As Comparative Example 2, an experiment was conducted in which one biological treatment tank was used in the example. FIG. 5 shows a schematic diagram of the experimental apparatus used in Comparative Example 2, and the apparatus specifications and processing conditions are described below.
[Biological treatment tank]
Volume; 32m ³
MLSS concentration: 4,000 mg / L
BOD tank mud load; 1.5 kg-BOD / m ³ / day HRT; 32 hours

  In Comparative Example 2, the solid-liquid separation means is also one. The other conditions were the same as in the example. As a result, the amount of excess sludge generated from the entire treatment apparatus 5 was 9.6 kg of excess sludge generated from the biological treatment tank per day, and the amount of excess sludge generated in the entire treatment apparatus 5 was Was 1.12 kg / day and the treated water quality (TOC concentration) was 30 mg / L.

  As described above, according to the present invention, it was possible to reduce the generation amount of excess sludge while reducing the volume of the biological treatment tank with a high organic load, and to obtain treated water with good water quality.

  The present invention can be used for the treatment of organic substance-containing water.

The schematic diagram of the biological treatment apparatus which concerns on 1st Embodiment of this invention. The schematic diagram of the biological treatment apparatus which concerns on 2nd Embodiment of this invention. The schematic diagram of the biological treatment apparatus which concerns on 3rd Embodiment of this invention. The schematic diagram of the biological treatment apparatus used in the comparative example 1. FIG. The schematic diagram of the biological treatment apparatus used in the comparative example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-5 Biological treatment apparatus 11 1st biological treatment apparatus 12 2nd biological treatment apparatus 13 Ozone reaction tank 14 Digestion tank 15 Carrier 21 1st solid-liquid separation means 22 2nd solid-liquid separation means 23 Centrifugal concentrator 24 Digested sludge concentrator

Claims (8)

A first biological treatment tank in which organic matter-containing water containing organic matter is introduced to perform aerobic treatment;
A first liquid that flows out of the first biological treatment tank is introduced, and the first treatment liquid is separated into a separated liquid and separated sludge in a floating separation tank without using an inorganic flocculant. Separation means, a second biological treatment tank in which the separation liquid is introduced and performs aerobic treatment,
See containing and a volume reduction means for compacting said separated sludge biologically,
The volume reducing means includes a concentrator that introduces digestion liquid flowing out from the high-temperature aerobic digestion tank, concentrates the digestion liquid and discharges the concentrated sludge and desorption liquid, and the concentrated sludge into the high-temperature aerobic digestion tank. A biological treatment apparatus for organic matter-containing water, further comprising: a concentrated sludge return path for returning to the water and a desorbed liquid return path for returning the desorbed liquid to the first biological treatment tank . The biological treatment apparatus for organic matter-containing water according to claim 1, wherein the second biological treatment tank is a carrier fluidized bed type. The biological treatment apparatus for organic matter-containing water according to claim 1, wherein the second biological treatment tank is a membrane activated sludge system. The biological treatment apparatus for organic matter-containing water according to any one of claims 1 to 3 , further comprising advanced treatment means for advanced treatment of the second treatment liquid flowing out of the second biological treatment tank. Organically containing water containing organic matter is treated aerobically in the first biological treatment tank,
The first treatment liquid flowing out from the first biological treatment tank is solid-liquid separated into a separation liquid and a separated sludge in a floating separation tank without using an inorganic flocculant,
Aerobically treating the separation liquid in a second biological treatment tank;
Introduce and concentrate the digested liquid flowing out of the high temperature aerobic digester, discharge the concentrated sludge and desorbed liquid,
Return the concentrated sludge to the high-temperature aerobic digester,
A biological treatment method for organic matter-containing water, wherein the desorbed liquid is returned to the first biological treatment tank to biologically reduce the separated sludge. The biological treatment method for organic substance-containing water according to claim 5 , wherein the second biological treatment tank is a carrier fluidized bed type. The biological treatment method for organic matter-containing water according to claim 5 , wherein the second biological treatment tank is a membrane activated sludge system. In the said 1st biological treatment tank, the biological treatment of the organic substance containing water in any one of Claim 5 to 7 which performs the aerobic treatment by the high load of BOD component volumetric load 2kg-BOD / m < ³ > / day or more. Method.

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