JP4610640B2 - Method and apparatus for treating organic wastewater - Google Patents

Description

  In the present invention, industrial wastewater with a high concentration of organic matter discharged from marine products processing, food processing, painting, papermaking, dyeing factories, etc. and high BOD (biochemical oxygen demand) is aerated with activated sludge to protect the environment. The present invention relates to a method and apparatus for treating organic wastewater that also serves to treat wastewater having a low concentration of organic matter and low BOD, such as general sewage, when processing so that the organic matter concentration and BOD can be discharged to rivers and the like to a level that does not impair it. Is.

  Generally, in factories where a large amount of waste water with a high organic matter content and high BOD is produced, a large amount of waste water with a low organic matter content and low BOD is also discharged at the same time, such as general municipal sewage. Since it is inconvenient and uneconomical to treat with a separate treatment apparatus suitable for each water quality, the apparatus shown in FIG. 2 is put into practical use for treating both together.

  FIG. 2 shows a conventional wastewater treatment apparatus of this type, which flocculates and settles suspended solids of so-called organic wastewater (hereinafter referred to as industrial wastewater) having a high organic substance-containing concentration by adding a coagulating and precipitating agent. A first agglomeration sedimentation tank 1, an aeration tank 2 in which the supernatant water is introduced, contains activated sludge, and performs aeration treatment to remove a predetermined amount of contained BOD under the use of metabolic activity of microorganisms; A sedimentation separation tank 3 that settles and separates the aerated activated sludge suspension into a supernatant and a solid suspension layer, and a supernatant that has a BOD reduced to its desired level. A treated water mixing tank 4 to be mixed with wastewater such as sewage (hereinafter referred to as general wastewater), and this mixed solution is agglomerated on the basis of addition of a treatment agent to form an aggregated precipitation flock to adsorb and collect solid matter. Environmental protection released as final treated water The second coagulation sedimentation tank 5 that settles and separates into a supernatant of the treated water quality and the solid suspension layer, and the solids extracted from the coagulation sedimentation tank 1, the sedimentation separation tank 3, and the coagulation sedimentation tank 5, respectively. A concentration tank 6 for concentrating and concentrating the material suspension layers 1a, 3a, and 5a, and a dehydration processing device using a press-type dewatering device 7 for dewatering the concentrated solid suspension layer 5a to form a residue cake; It has. This dehydrator can also be a centrifugal separator.

  The coagulation sedimentation tank 1 is provided with a supernatant liquid deriving means 1b constituted by a metering / adding device 1d for coagulation / precipitation medicine and a pipe attached to a pump for deriving the supernatant liquid to the aeration tank 2. Yes. The aeration tank 2 includes an activated sludge addition device 2d, an air exposure device 2a that is provided with a porous air diffuser tube at the immersion part and performs stirring by air supply, and an activated sludge suspension that has been subjected to aeration treatment. The suspension deriving means 2b having the same configuration for deriving to 3 is attached. The sedimentation separation tank 3 includes a similar supernatant liquid deriving means 3b for deriving the supernatant to the treated water mixing tank 4, and a pump attached to feed back the sedimentation sludge solid matter suspension layer to the aeration tank 2. Return means 3d composed of a pipe or the like is attached. The treated water mixing tank 4 is provided with a mixed liquid deriving means 4 d composed of a pipe attached to a pump for leading the mixed liquid to the coagulation sedimentation tank 5. The coagulating sedimentation tank 5 is provided with a metering device 5d for coagulating and precipitating chemicals. The coagulation sedimentation tank 1, the sedimentation separation tank 3 and the coagulation sedimentation tank 5 are suspensions composed of pipes attached to a pump for extracting the settled solid suspension layers 1 a, 3 a, 5 a to the concentration tank 6. Muddy layer extraction means 1c, 3c, 5c are attached. The concentration and sedimentation tank 6 and the dewatering device 7 are provided with similar derivation means 6b and 7b for deriving the supernatant liquid and the separated water to the treated water mixing tank 4, respectively. Precipitated solid content deriving means 6 c constituted by a pipe attached to a pump for sending the precipitated solid content, which is a concentrated solid suspension layer of the sedimentation tank 6, to the dehydrator 7 is interposed.

  The industrial wastewater is introduced into the coagulation sedimentation tank 1 and the coagulant is added to form coagulation sedimentation flocs, and fine suspensions and giant organic molecules are adsorbed on this to settle and separate. The obtained supernatant is guided to the aeration tank 2 containing activated sludge and stays at a predetermined level until the BOD is lowered to a desired level through the uptake and biodegradation of dissolved organic matter by metabolism of microorganisms in the activated sludge. Aeration is performed over time. The activated sludge suspension that has been subjected to aeration is introduced into the sedimentation separation tank 3 where the suspended sludge is settled and separated, and the supernatant liquid whose BOD has been lowered to the desired level is mixed in the general wastewater and treated water mixing tank 4. The mixed waste water is introduced into the coagulation sedimentation tank 5, and by adding the coagulation agent, coagulation sedimentation flocs are formed to adsorb and collect solids, and settle and separate to obtain a treated water quality meeting the environmental protection standards. Released to general rivers. At that time, the solid suspension layer 3a of the sedimentation separation tank 3 controls the amount of microorganisms according to the BOD load of the aeration tank 2 to balance the MLSS (Mixed liquor Suspended Solid) concentration in the aeration tank 2. An appropriate amount will be returned. In the treated water mixing tank 4, the supernatant liquid and the separated water are also mixed.

On the other hand, in Patent Document 1, raw wastewater is subjected to an activated sludge / aeration process after being subjected to a normal pretreatment in a regulating tank, and is separated from the mixed liquid (ML) after the aeration process. A technique for treating organic wastewater in which a part of the activated sludge sedimentation layer is extracted and subjected to oxidative sterilization and solubilization treatment, returned to the adjustment tank, and mixed with the raw wastewater is disclosed.
JP 2004-188356 A

  However, in the apparatus of FIG. 2, the solid suspension layer 1a extracted from the coagulation sedimentation tank 1 contains organic matter at a high concentration, and in addition to technical problems, the dehydration takes into account measures against spoilage and insect pests. The solid suspension layer 3a from the sedimentation separation tank 3 contains a large amount of activated sludge flocs, so that the filter of the dewatering device is likely to be clogged, and the dissimilar solid content suspension layer is dewatered together. In this case, there is a problem that the operation becomes unstable. In addition, the aeration treatment using activated sludge takes a long time (necessary to design a longer residence time in the aeration tank) because the treatment efficiency of reducing the organic matter content concentration and BOD to the desired level is not high. Was also a problem.

  On the other hand, the organic wastewater treatment technology of Patent Document 1 provides feedback of the sterilization treatment liquid of activated sludge to the adjustment tank that performs aeration treatment, but is intended to reduce the amount of accumulated activated sludge. There is no mention of simultaneous treatment of polluted organic waste water and low polluted general waste water or improvement of dewaterability of solid residue.

  In view of such points, the present invention lowers the BOD of organic wastewater having a high organic substance-containing concentration to a desired level, and further reduces BOD when coagulated and discharged together with general wastewater, And it aims at providing the processing method and apparatus of organic waste water which can simplify the dehydration operation | work of a solid substance suspended layer.

  In order to solve such problems, the present inventor has conducted various studies, and as a result, extracted from the settling separation tank of the coagulation sedimentation suspension layer extracted from the first coagulation sedimentation tank and the activated sludge after aeration treatment. The sedimented sludge suspension layer is combined and introduced into the sludge reprocessing tank, the mixed suspension is aerated again, and then the re-aerated suspension is treated with a general system with a low concentration of organic matter. The above-mentioned problems in the prior art are solved by a simple means of mixing with waste water and leading to a second coagulating sedimentation tank where a coagulant is added to form coagulated flocs and coagulating and separating solids. The present invention was reached.

  As described above, in the prior art, the treated water from activated sludge-aerated treatment of industrial wastewater with high organic matter content is mixed with general wastewater with low organic matter content, and this mixed water is coagulated and precipitated by adding a flocculant. However, when the solid precipitates generated during this treatment are dehydrated to form a residual cake, the solids containing activated sludge are not easy to dehydrate and require a long time. For example, additional measures such as the addition of a promoter were employed, and the dehydration treatment was forced to be performed separately from other coagulated sediment solids. As in the present invention, the separated solid content from the primary treatment (coagulation precipitation treatment) of industrial wastewater (mainly suspended solids in the wastewater—SS—) and the activity of the supernatant of this primary treatment Combine sediment sludge layer from sludge / aeration treatment, aeration treatment again, and add the resulting solid suspension to the mixed water of supernatant water and general wastewater from the activated sludge / aeration treatment By adopting a simple means for coagulating and sedimenting the suspended solid (SS) in the mixed liquid (ML) with a flocculant, the problems associated with the prior art as described above, namely activated sludge The efficiency of the aeration process using the water is low, and a long residence time is required to process to a BOD value that can be discharged harmlessly in general rivers, the efficiency of dewatering the separated solids is low, and the filter is easily clogged, etc. We were able to solve the problem. In addition, the present invention contributes to reducing fluctuations in treated water quality, and the separated residue cake always maintains certain physical properties, so that such treated residue can be used as an agricultural soil modifier. It has been found that it also provides an unexpected benefit to be helpful.

  Therefore, according to claim 1, the method of the present invention introduces organic waste water having a high organic substance-containing concentration into the first coagulation sedimentation tank, and coagulates and precipitates the suspended solids under the addition of the treatment agent, The supernatant is introduced into an aeration tank containing activated sludge and subjected to aeration treatment to remove a predetermined amount of BOD contained using the metabolic activity of microorganisms, and the aeration treatment liquid is transferred to a sedimentation separation tank. Introducing activated sludge to sedimentation, and introducing the supernatant together with wastewater with low organic matter content into the second coagulation sedimentation tank and coagulating sedimentation of suspended solids with the addition of treatment chemicals In the method for treating organic wastewater in which the supernatant is discharged as treated water to a river or the like, the solid suspended layer settled and separated in the first coagulating sedimentation tank and the activated sludge settled and separated in the sedimentation separation tank The solid suspension layer containing The aerated solid suspension is aerated, and the aerated solid suspension is mixed with the waste liquid having a low concentration of organic matter together with the supernatant of the sedimentation separation tank and introduced into the second coagulation sedimentation tank. It is characterized by doing.

  According to claim 4, the apparatus of the present invention comprises a first coagulation sedimentation tank that coagulates and settles the suspended solid content of the introduced organic wastewater having a high organic substance-containing concentration by adding a chemical for coagulation sedimentation, and the coagulation sedimentation tank. The aeration tank in which the supernatant introduced from the aeration process is aerated on the basis of the addition of activated sludge, and the activated sludge suspension after the aeration treatment introduced from the aeration tank is separated from the supernatant and solid suspension. A settling separation tank that separates into a turbid layer, a treated water mixing tank that mixes the introduced general wastewater with a low organic substance-containing concentration with the supernatant introduced from the settling separation tank, and this treated water mixing tank The second coagulating sediment that separates the coagulating sediment suspension produced by adding the coagulating sediment agent into the mixed solution introduced from the liquid into a supernatant and a solid suspension layer discharged as final treated water The tank and the solid suspension layer generated in the process are dehydrated and taken as a residual cake. In the organic waste liquid processing apparatus provided with the dehydration processing apparatus for sewage, the solid substance containing the solid suspension layer settled and separated in the first coagulating sedimentation tank and the activated sludge settled and separated in the sedimentation tank A sludge reprocessing tank for aeration treatment of the solid suspension from which the suspension layer has been extracted is combined, and the activated sludge suspension aerated in this sludge reprocessing tank is a treated water mixing tank It is introduced in.

  According to the invention of claim 1 or claim 4, the separated solid content from the primary treatment (coagulation sedimentation treatment) of industrial wastewater, and the activated sludge / aerated sludge layer of the supernatant of this primary treatment The mixed suspension obtained by coalescence is aerated again, and the aerated mixed suspension is added to the mixed water of the supernatant water and the general wastewater from the activated sludge / aerated treatment. When coagulating and sedimenting suspended solids in the mixed liquid with a flocculant, organic industrial wastewater is treated with general wastewater and discharged into a general river as treated water with quality that does not impair the environment. Activated sludge / aeration treatment time can be shortened, filter clogging due to low efficiency of separating and dewatering suspended solids in the treatment liquid can be suppressed, and one type of sludge to be dewatered is extracted.・ Feeding operation becomes easy and the final amount of residue It is reduced. High-concentration organic wastewater discharged from large-scale painting, marine product processing, food processing, paper manufacturing, dyeing factories, etc. is also effectively treated.

  At that time, according to the invention of claim 2, even for organic wastewater having a high concentration of typical BOD value discharged from factories or the like, a BOD value of 20 mg / liter or less is usually required for activated sludge / aeration treatment. It is applied to the treatment with a large amount of general wastewater with low environmental pollution load. According to invention of Claim 3 or Claim 5, the dehydration processing apparatus which produces | generates the residue cake which further solidified sludge is comprised by the slight change simplified with respect to the conventional apparatus, Maintenance work of a dehydration apparatus The clogging can be avoided even in the case of a press type rather than a centrifugal type.

  FIG. 1 illustrates a wastewater treatment apparatus according to an embodiment of the present invention, and the same or equivalent parts as those shown in FIG. As described above, this apparatus performs wastewater treatment in two series according to the difference in the concentration of organic wastewater, and follows the treated water mixing tank 4 and the aeration tank 2 into which general wastewater having a low organic concentration is introduced. The sludge reprocessing tank 10 is interposed by the present invention between the settling separation tank 3.

  Highly polluted industrial wastewater passes through a primary screening section such as a sand basin (not shown), and is then introduced into the first coagulating sedimentation tank 1, for example, aluminum sulfate and an alkali agent, magnesium chloride and an alkali agent, Add a flocculant such as iron chloride and an alkali agent, or add an agglomeration aid such as activated silicic acid or synthetic polymer agglomeration aid to form an agglomeration precipitation flock, and in that case suspended solids in waste water Suspended solids and giant organic molecules are adsorbed and settled and separated.

  The supernatant liquid in which the suspended solids are settled and removed as the solid suspension layer 1a in the coagulation sedimentation tank 1 is then introduced into the aeration tank 2 containing activated sludge. This aeration tank is aerated by blowing air, and BOD-causing substances such as dissolved organic matter in the supernatant are taken into cells by the metabolic activity of microorganisms constituting the activated sludge, or biodegraded. It is configured to stay until it is reduced to a predetermined BOD value. The activated sludge suspension thus aerated for a predetermined residence time is introduced into the sedimentation separation tank 3, and the suspended activated sludge solids are settled and separated as the solid suspension layer 3a, and the BOD value is desired. The supernatant liquid reduced to the value of is mixed in the general waste water and the treated water mixing tank 4.

  The sludge reprocessing tank 10 is introduced with the solid suspension layer 1a separated by coagulation sedimentation in the coagulation sedimentation tank 1 by the suspension layer extraction means 11c, and from the sedimentation separation tank 3 by the suspension layer extraction means 13c, A solid suspension layer 3a containing a certain amount of activated sludge separated and separated is introduced, and in order to re-aerate the solid suspension mixed with the sludge, air is introduced into the tank at the bottom of the tank. An aeration apparatus 10 d for blowing in water is provided, and reprocessing liquid deriving means 11 including a pipe attached to a pump for deriving the suspension subjected to the reaeration treatment to the treated water mixing tank 4 is provided. . Incidentally, unlike the aeration tank 2, the activated sludge addition apparatus and the return means are not provided.

  In such a sludge reprocessing tank 10, re-aeration is performed until the COD (chemical oxygen demand) value of the filtrate of the activated sludge mixed liquid is almost halved. For this, a residence time of 3 days or more is required, but in continuous operation, the sludge suspension subjected to the re-aeration treatment is continuously derived from the vicinity of the bottom of the tank with respect to the introduction from above. Therefore, a residence time of 3 days can be secured. This re-aerated sludge suspension is composed of the residue from the organic matter separated from the industrial wastewater and the organic matter adsorbed by the activated sludge floc, the sludge microorganisms separated from the aeration tank 2, and the agglomeration The presence of these coarse particulate solids, including precipitated inorganic solids and suspended solids in industrial wastewater, contributes to the good dewaterability of the residual cake produced in the subsequent dewatering process. The general wastewater mixed with this re-aerated solid suspension is introduced into the second coagulation sedimentation tank 5 and, as in the coagulation sedimentation tank 1, addition of inorganic coagulant, coagulant aid, etc. The suspended solids are settled and separated by the coagulation sedimentation floc formed on the basis of the above, and the treated water of water quality that does not impair the environment is obtained as supernatant water, and can be discharged as it is into a general river. In the sludge reprocessing tank 10, the BOD load of the coagulation sedimentation tank 1 and the amount of activated sludge in the sedimentation tank 3 increase or decrease in parallel and gradually balance, and the MLSS can follow the BOD load.

  The solid suspension layer 5a settled and separated in the coagulation sedimentation tank 5 is preferably sent to the concentration tank 6 where the solid content is further concentrated, and the solid content layer thus concentrated and separated is extracted to the dehydrator 7. And take out as a residue cake which is the final processing residue. At that time, by coagulating and precipitating the general wastewater by mixing the re-aerated sludge, the separated solid content discharged from the apparatus is single, and the dehydrating effect of the separated solid content is enhanced. A residue cake of the same quality can be obtained easily and constantly. Thereby, high processing efficiency and the high availability of a final process residue can be achieved only by adding the sludge reprocessing tank 10 using the conventional apparatus shown in FIG.

Hereinafter, examples using the wastewater treatment apparatus of the present invention will be described.
Example 1.
Organic wastewater having a BOD value of about 1,000 to 2,000 mg / liter and suspended solids (SS) of about 1,000 to 4,000 mg / liter is discharged in an amount of 150 t / day in a vehicle painting plant. . In this factory, low-pollution general wastewater having a BOD value of about 17 mg / liter is also discharged in an amount of about 1,350 t / day. That is, the aforementioned organic wastewater is fed to the coagulation sedimentation tank 1, and ferric hydroxide is precipitated by adding 2,500 mg of a flocculant (ferric chloride) and 500 mg of an alkaline agent (slaked lime) per liter of wastewater. The SS was settled and separated based on the formation of flocs, and the supernatant obtained at that time was sent to the aeration tank 2. The aeration tank 2 is an open tank with a volume of 300 m ³ in which an aeration apparatus equipped with a porous diffuser tube is provided at the bottom of the tank. The aeration tank 2 is configured to discharge waste water and discharge the treatment liquid so that a BOD load of 200 kg / day is obtained. While performing continuously, aeration treatment was performed at DO value of 2 ± 0.5.

  An appropriate amount of activated sludge was previously added to the aeration tank 2 before the start of operation. During continuous operation, a part of the sludge extracted from the settling separation tank 3 is continuously returned to the aeration tank 2. It is configured. The activated sludge / aerated sludge mixed liquid (Mixed Liquor) in the aeration tank 2 is continuously discharged from the tank outlet and led to the settling separation tank 3 where the suspended sludge (Mixed) of the activated sludge is mixed. Liquor Suspended Solids) agglomerate to form flocs while staying in the tank, and settle to separate from the mother liquor to form a solid suspension layer 3a containing activated sludge. The solid suspension layer is continuously extracted from the bottom of the tank, but is sent back to the aeration tank 2 at a return ratio of about 50%, and the remaining portion is a solid suspension layer separated and settled in the coagulation sedimentation tank 1. It is sent to the sludge reprocessing tank 10 together with 1a. The mother liquor of the sludge mixed liquid whose BOD value has been lowered to a predetermined level by activated sludge / aeration treatment in the aeration tank 2 is separated from the suspended solids in the sedimentation separation tank 3, and is continuously discharged from there as a supernatant. Then, it is sent to the treated water mixing tank 4 and united with general waste water having a low BOD value.

In the sludge reprocessing tank 10, the mixed suspension of the solid precipitate layer 1 a by aggregation and the solid precipitate layer 3 a containing activated sludge is blown with air at a flow rate of 6 Nm ³ / min from the air exposure device, Upon receiving aeration treatment for a residence time of 72 hours, the organic matter content of this mixed suspension was reduced to 1/2 as COD (chemical oxygen demand). The solid suspension thus subjected to aeration treatment is added to the combined water of the above general wastewater and the mother liquor subjected to the aeration treatment at a steady charge of about 15 kg or about 1.5 percent per ton of water. Then, the combined waste water mixed with the aerated mixed solid layer was introduced into the coagulating sedimentation tank 5 in an amount of about 1,500 tons / day. In this coagulation sedimentation tank, as in the coagulation sedimentation tank 1, a coagulant composed of ferric chloride and slaked lime and a polymer coagulant aid are added to form ferric hydroxide precipitation flocs, thereby forming sludge. Solids, suspended solids in waste water, and 1 part of organic matter in the wastewater were adsorbed on the floc to promote sedimentation separation, and a solid precipitate layer 5a with good dehydration property was obtained. The supernatant water from which the suspended solids were settled and separated had a BOD value of about 7 mg / liter or less, and could be discharged as a treated water into a general river as it was.

  The solid suspension layer 5a separated in the coagulation sedimentation tank 5 was directly extracted into a filter press type dehydration apparatus, and a residual cake having a water content of about 60% was obtained without any problem. The residue cake was further naturally dried to further reduce the water content. The separated water from the dehydration apparatus was led to the treated water mixed layer 4.

Example 2.
The same factory wastewater was treated in the same manner as in Example 1, but in this example, the solid suspension layer 5a drawn from the coagulation sedimentation tank 5 was introduced into the concentration tank 6 and concentrated, and the concentrated sedimentation layer was belt-pressed. It was fed to a dehydrator 7 of the type and dehydrated, whereby a residue cake was obtained by a final treatment having a water content of about 60%. Separation water was sent back to the treated water mixing tank 4 by the dehydrator 7 and a treated residue cake of the same quality was smoothly obtained without clogging the filter.

Comparative Example 1
The same plant wastewater was treated using the existing equipment portion of the equipment used in Example 2 according to the prior art, but was not separated in the coagulation sedimentation tank 1 according to the conventional treatment technique without using the sludge reprocessing tank 10. The solid suspension layer 1a and the solid suspension layer 3a separated in the sedimentation separation tank 3 are directly introduced into the concentration tank 6 together with the solid suspension layer 5a from the coagulation sedimentation tank 5 and concentrated solid content layers together. The supernatant water was sent back to the treated water mixing tank 4 and the concentrated solid content layer was extracted to the press-type dehydrator 7 and dehydrated. The treated water discharged from the coagulation sedimentation tank 5 had a BOD value of about 20 mg / liter. The concentrated solid content layer sent from the concentration tank 6 to the dehydrating device 7 has strong adhesion of sludge solids and poor dewaterability, resulting in clogging of the dehydrating device and requiring additional treatment of lime addition.

It is a figure explaining the structure of the organic waste water treatment apparatus by embodiment of this invention. It is a figure explaining the structure of the conventional organic wastewater treatment apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st coagulation sedimentation tank 1a, 3a, 5a Solid matter suspension layer 2 Aeration tank 3 Settling separation tank 4 Treated water mixing tank 5 2nd coagulation sedimentation tank 6 Concentration tank 7 Dehydrator 10 Sludge reprocessing tank

Claims (5)

Organic waste water with a high concentration of organic matter is introduced into the first coagulation sedimentation tank, and the suspended solids are coagulated and settled under the addition of the treatment chemical, and the supernatant is aerated with an activated sludge. And aeration treatment to remove a predetermined amount of BOD contained using the metabolic activity of microorganisms, introduce the aeration treatment liquid into a sedimentation separation tank, and separate activated sludge by sedimentation. The liquid is introduced into the second coagulation sedimentation tank together with wastewater with a low concentration of organic matter, and the suspended solids are coagulated by sedimentation under the addition of the treatment chemical. In the treatment method of organic wastewater to be discharged,
The solid suspension layer settled and separated in the first coagulation sedimentation tank and the solid suspension layer containing activated sludge separated and settled in the sedimentation separation tank are introduced into the sludge reprocessing tank, and the mixed solid Aeration of the material suspension,
The solid waste suspension that has been aerated is mixed with the supernatant of the sedimentation separation tank together with the waste water having a low concentration of organic matter and introduced into the second coagulation sedimentation tank, and the organic waste water is treated. Method.   2. The organic wastewater according to claim 1, wherein the organic wastewater with a high organic matter content concentration contains 600 to 5,000 mg / l BOD, and the wastewater with a low organic matter content concentration contains BOD of 20 mg / l or less. Processing method.   The solid suspension layer settled and separated in the second coagulation sedimentation tank is extracted and introduced into a concentration tank, the solid suspension layer sedimented and concentrated is introduced into a dehydrator, and the solid content is separated as a residue cake, 2. The organic waste water according to claim 1, wherein the separated water separated by the dehydrator is mixed with waste water having a low concentration of organic matter together with the supernatant of the concentration tank and introduced into the second coagulation sedimentation tank. Processing method. A first coagulation sedimentation tank that coagulates and settles the suspended solid content of the introduced organic wastewater with a high organic substance-containing concentration by adding an agent for coagulation sedimentation, and the supernatant introduced from the coagulation sedimentation tank is activated sludge. An aeration tank that performs an aeration treatment based on the addition of the above, a sedimentation separation tank that separates the activated sludge suspension that has been aerated from the aeration tank into a supernatant and a solid suspension layer, A treated water mixing tank that mixes the introduced general wastewater with a low concentration of organic matter with the supernatant introduced from the settling tank, and the mixture introduced from the treated water mixing tank is used for coagulation precipitation. A second agglomeration sedimentation tank for separating the agglomerated sediment suspension produced by adding the chemicals into a supernatant and a solids suspended layer to be discharged as final treated water; Equipped with a dehydration device for dewatering the turbid layer and taking it out as a residual cake In the processing apparatus of the machine waste water,
A solid suspension obtained by extracting and combining the solid suspension layer sedimented and separated in the first coagulation sedimentation tank and the solid suspension layer containing activated sludge separated and settled in the sedimentation separation tank An organic wastewater treatment apparatus comprising an activated sludge suspension aerated in the sludge reprocessing tank, and an activated sludge suspension aerated in the sludge reprocessing tank.   As a dehydration apparatus, a concentration tank for further sedimentation and concentration of the solid suspension layer extracted from the second coagulation sedimentation tank, and a dehydrator for dehydrating the solid suspension layer introduced from the concentration tank 5. The apparatus for treating organic wastewater according to claim 4, wherein the supernatant of the concentration tank and the separated water of the dehydrator are introduced into a treated water mixing tank.

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