JP4655974B2 - Waste water treatment method and treatment apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for treating wastewater containing hardly water-soluble suspended substances such as oil and organic matter, and in particular, combined floating treatment and biological treatment for removing hardly water-soluble substances from wastewater. The present invention relates to a wastewater treatment method and apparatus.

  Conventionally, as a method for treating organic wastewater containing organic matter, biological treatment utilizing the action of various microorganisms that grow using the organic matter as a substrate is known. For example, as a method for biological treatment under aerobic conditions, an activated sludge method using an aerobic microorganism community called activated sludge, or a method for biological treatment under anaerobic conditions includes acid-producing bacteria and methane. A methane fermentation method using the producing bacteria (hereinafter sometimes collectively referred to as “methane fermentation bacteria”) is known.

  Biological treatment methods use organic microorganisms to decompose organic matter and thus have a low treatment cost, and are widely used for the treatment of industrial wastewater or sewage. However, biodegradation does not proceed well when wastewater contains substances that inhibit microbial activity. For example, since oils, surfactants, dispersants, and the like are difficult to be microbially decomposed, there is a possibility of causing problems such as inhibiting microbial activity and remaining in treated water without being decomposed during the biological treatment process.

Therefore, a method has been proposed in which a hardly decomposable substance is separated from a liquid component in advance before biological treatment of wastewater containing the hardly decomposable substance. For example, Patent Document 1 discloses a treatment method in which lipase is added to oil-and-fat-containing water to hydrolyze the oil and fat, followed by methane fermentation. According to the method disclosed in Patent Document 1, since the fat and oil is hydrolyzed prior to biological treatment, the liquid to be treated that is subjected to methane fermentation is easily microbially decomposed, and a reduction in treatment efficiency in the biological treatment step can be prevented.
JP-A-6-246295

  In the method described in Patent Document 1, it is necessary to add lipase in order to hydrolyze fats and oils, so that the processing cost increases. On the other hand, if it is configured to remove fats and oils by performing solid-liquid separation operation such as flotation separation before biological treatment of organic matter-containing wastewater containing poorly water-soluble substances such as fats and oils, it is unique No additives are necessary. However, in such a configuration, a coagulation sedimentation tank or a pressure levitation tank is separately provided before the biological treatment step, and thus there is a problem that the configuration of the processing apparatus becomes complicated and the apparatus installation area increases.

  The present invention has been made in view of the above problems, avoids an increase in the size of the apparatus with a simple configuration, and can prevent a reduction in treatment efficiency when biologically treating water to be treated containing a substance such as oil. It aims at providing a processing method and equipment.

  As a result of studying to solve the above problems, the present inventor has found that flotation separation can be performed using a gas generated in the process of biologically treating wastewater under anaerobic conditions, and has completed the present invention. Specifically, the present invention provides the following.

(1) By introducing waste water containing a poorly water-soluble substance and an organic substance into a sealable container and anaerobically biologically treating the floc in a coexisting state with floc, the gas is generated in the waste water. Pressurized wastewater generation step for obtaining pressurized wastewater contained in a pressurized state, and by depressurizing the pressurized wastewater, the poorly water-soluble substance is caused to float on the adsorbed floc adsorbed on the floc and separate from the liquid component And supplying the airtight container with the sludge generated in the post-treatment step as the floc, and a floating separation step for obtaining the adsorption floc and the separation water, and a post-treatment step for treating the separation water with activated sludge. processing method of waste water.
(2) By introducing waste water containing a poorly water-soluble substance and organic matter into a sealable container and anaerobically biotreating the floc in a coexisting state to generate gas, the gas is added to the waste water. Pressurized wastewater generation step for obtaining pressurized wastewater contained in a pressurized state, and by depressurizing the pressurized wastewater, the poorly water-soluble substance is caused to float on the adsorbed floc adsorbed on the floc and separate from the liquid component The floating separation step for obtaining the adsorption floc and the separation water, the methane generation step for introducing the separation water into a methane generation tank and performing methane fermentation, and the treated sludge treatment of the treated water obtained in the methane generation step A post-treatment step, the sludge produced in the post-treatment step is supplied to the sealed container as the floc, and in the pressurized waste water production step, acid treatment by acid-producing bacteria is performed as a biological treatment. Law.
(3) The method for treating wastewater according to (1) or (2), wherein the poorly water-soluble substance is oil.
(4) The wastewater treatment according to any one of (1) to (3), further comprising a coagulation reaction step of adding a flocculant to the wastewater to form the floc before the pressurized wastewater generation step. Method.
(5) Provide a sealable container into which waste water containing a poorly water-soluble substance and an organic substance is introduced, and generate gas by anaerobically biologically treating the waste water in the presence of floc in the container. The pressurized waste water generating means for obtaining pressurized waste water containing the gas in a pressurized state in the waste water, and the adsorption floc in which the poorly water-soluble substance is adsorbed on the floc by depressurizing the pressurized waste water Floating separation means for separating the liquid from the liquid to obtain the adsorption floc and separation water, a post-treatment tank for introducing activated water sludge by introducing the separation water, and sludge generated in the post-treatment tank. A wastewater treatment apparatus comprising: a sludge floc supply path for supplying the container as the floc.
(6) Provide a sealable container into which waste water containing a poorly water-soluble substance and organic matter is introduced, and generate gas by anaerobically biologically treating the waste water in the presence of floc in the container. The pressurized waste water generating means for obtaining pressurized waste water containing the gas in a pressurized state in the waste water, and the adsorption floc in which the poorly water-soluble substance is adsorbed on the floc by depressurizing the pressurized waste water The floating separation means for floating the liquid and separating it from the liquid to obtain the adsorption floc and separated water, the methane production tank for introducing the separated water to perform methane fermentation, and the treated water flowing out from the methane production tank are introduced. A post-treatment tank for treating activated sludge, and a sludge floc supply path for supplying the sludge produced in the post-treatment tank to the container as the floc, wherein the container holds acid-producing bacteria and generates acid. I will do Processing apparatus wastewater are configured.
(7) The wastewater treatment apparatus according to ( 5) or (6), wherein the floating separation means includes a valve that can be opened and closed provided in the container.
(8) A coagulation reaction tank for adding a flocculant to the waste water to form the floc, and a coagulation floc supply path for supplying the floc generated in front of the coagulation reaction tank to the container. (5) The wastewater treatment apparatus according to any one of (7).

  In the present specification, the “poorly water-soluble substance” refers to a solid that exists as SS in water and a liquid that undergoes phase separation without being mixed with water near room temperature. Specific examples include oil, surfactant, milk protein, and dispersant.

  “Flock” refers to a suspended matter in which SSs are gathered. The flocs may be biologically formed flocs (aggregates of microorganisms) or may be flocculent flocs formed by the addition of flocculants.

  As a biological treatment in the pressurized wastewater production step, a treatment in which a biological reaction that produces a gas using an organic substance as a substrate is performed under anaerobic conditions in which the oxygen concentration in the liquid to be treated is almost zero. Specific examples include methane fermentation and heterotrophic denitrification.

  Methane fermentation is divided into an “acid production step” in which an acid such as butyric acid is produced using sugar or protein as a substrate, and a “methane production step” in which methane is produced from acetic acid or hydrogen. The acid production step can be further divided into a “lower fatty acid production step” for producing lower fatty acids such as butyric acid and propionic acid from sugar and the like, and an “acetic acid production step” for producing acetic acid from lower fatty acids. In the pressurized wastewater generation step, the methane fermentation step may be divided into two or more, and only one of the steps may be performed as a biological treatment for generating pressurized wastewater.

  The gas produced in the pressurized wastewater production process is a gas produced by metabolic activity of microorganisms (sometimes referred to as “microbe production gas”), and specifically, carbon dioxide produced in the methane fermentation process. Methane gas, hydrogen gas, and nitrogen gas produced in the denitrification process.

  In this pressurized wastewater generation process, wastewater containing poorly water-soluble substances and organic substances is introduced into a sealable container and treated by a biological reaction involving gas generation under anaerobic conditions, so that the generated gas is contained in the container. It will be dissolved in the liquid under pressure. For this reason, the liquid (pressure waste water) containing the microorganism-generated gas in the container is suddenly released to atmospheric pressure, whereby the gas dissolved in the pressurized state floats as micro bubbles called micro air. At this time, the fine bubbles and the poorly water-soluble substance adhere to the floc, and the adsorption floc that has adsorbed the poorly water-soluble substance floats near the liquid surface in the container.Therefore, the poorly water-soluble substance is separated by separating the adsorption floc from the liquid. Can be removed. For this reason, the fall of the processing efficiency at the time of carrying out biological treatment of the separated water further can be prevented.

  In particular, since oil has a low specific gravity, it can be floated and separated satisfactorily even if the amount of micro air produced is small.

  Anaerobic treatment of wastewater containing organic matter is suitable for the treatment of high-concentration organic wastewater whose organic matter (BOD) concentration expressed by biochemical oxygen consumption is about 1,000 mg / L or more, while treating the water quality at a level that allows sewage discharge. It is difficult to get water. For this reason, when methane fermentation is performed in the pressurized wastewater generation step, the treated water after methane fermentation may contain about several hundred mg / L of organic matter. Therefore, in the post-treatment process, when the treated water after methane fermentation is treated by the activated sludge method, the organic matter remaining in the methane fermentation treated water can be further decomposed to obtain treated water with good water quality. Moreover, the sludge (biological floc) produced | generated at a post-processing process can be utilized as a floc to which a poorly water-soluble substance adheres in the case of floating separation.

  The floc required for flotation separation may be generated by adding a flocculant to the wastewater introduced into the pressurized wastewater generation step.

In addition, the methane fermentation process is divided into at least an acid generation process and a methane generation process, and after the acid generation process is performed in the pressurized wastewater generation process, the pressure wastewater is subjected to solid-liquid separation in the floating separation process, and the resulting separation is obtained. Water may be treated in the methane production step. In this case, the separated water in which the sugar or the like is converted into an acid and the SS concentration is reduced can be used as the liquid to be treated in the methane production step. Since such separated water can be subjected to a high load treatment in a high load type methane fermentation tank holding granule sludge and the like, the treatment apparatus can be further downsized. In the present specification, “high load” means that, for example, the volume load of an organic substance (CODcr) represented by chemical oxygen consumption can be 2 kg-CODcr / m ³ / d or more.

  As a method for releasing the pressurized waste water at atmospheric pressure at once, there is a method in which a valve is provided in a sealable container and the inside of the container is rapidly depressurized by opening the valve. In addition, a flotation separation tank that performs flotation separation is provided separately from the biological treatment tank that generates pressurized wastewater, the biological treatment tank and the flotation separation tank are connected by a passage having a pressure reducing valve, and the pressurized wastewater is floated from this passage. You may lead to a separation tank and release atmospheric pressure at a stretch.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that a processing apparatus becomes excessive by using an anaerobic processing tank as a floating separation tank, and can prevent the biological treatment efficiency from falling.

  Hereinafter, with reference to the drawings, an embodiment in which the present invention is carried out using oil-containing wastewater as a wastewater containing a hardly water-soluble substance and an organic substance will be described. Hereinafter, members having the same function are denoted by the same reference numerals.

  FIG. 1 is a system diagram showing an embodiment of a method and apparatus for treating fat and oil-containing wastewater according to the first embodiment. The treatment apparatus 101 includes a raw water storage tank 1, a coagulation reaction tank 2, an acid generation tank 3, a high load methane generation tank 5, a post-treatment tank 6, and a settling tank 7, which are connected in series in this order. . The processing apparatus 101 also includes a methane fermentation tank 8, a sludge dehydrator 9, a desulfurization tower 10, and a gas holder 11 as accompanying equipment.

  The raw water storage tank 1 is connected to the raw water pipe 21 and one end edge of the desorption liquid pipe 40. The other end of the desorbed liquid pipe 40 is connected to the sludge dehydrator 9, and the oil-containing waste water and the sludge dehydrated filtrate (desorbed liquid) pass through the raw water pipe 21 and the desorbed liquid pipe 40, respectively. To be temporarily stored. The raw water storage tank 1 is connected to the agglomeration reaction tank 2 via an introduction pipe 22, and a mixed liquid of oil-containing waste water and desorption liquid is introduced into the aggregation reaction tank 2 as raw water.

  A coagulant injection pipe 23 is connected to the coagulation reaction tank 2, and the coagulant stored in the coagulant storage tank 2B is added to coagulate the raw water. The flocculant added to the raw water in the flocculation reaction tank 2 is not particularly limited, and an inorganic flocculant such as an iron salt and an aluminum salt, or an organic polymer flocculant such as an anionic, cationic or amphoteric polymer is used alone or in combination. Can be used. In the agglomeration reaction tank 2, a flocculant floc is formed by adding a flocculant to the raw water and stirring. For this reason, the agglomerated water that flows out of the agglomeration reaction tank 2 includes agglomerated floc, and the agglomerated water pipe 24 constitutes an agglomerated floc supply path.

  The aggregation reaction tank 2 and the acid generation tank 3 are connected to each other via an aggregation treatment water pipe 24, and the aggregation treatment water is introduced into the acid generation tank 3 from the aggregation treatment water pipe 24. In the present embodiment, the acid generation tank 3 includes a pressure-resistant container that can be sealed, and a valve V that can be opened and closed is provided in the pressure-resistant container. Acid producing bacteria are held in the container, and an acid producing reaction is performed as an anaerobic biological treatment in a state in which raw water is supplied, the valve V is closed and the container is sealed.

  In the acid generation step, butyric acid, propionic acid, acetic acid, and the like are generated using an organic substance contained in the raw water as a substrate, and a gas mainly containing carbon dioxide gas is generated along with the acid generation. The inside of the container of the acid generation tank 3 is in a pressurized state by gas generation, and pressurized waste water containing the generated acid and gas is obtained. Thus, in this embodiment, the container of the acid production | generation tank 3 functions as a pressurized waste water production | generation means. In addition, hydrogen sulfide, ammonia, etc. may be contained in the gas produced | generated with acid production | generation. Therefore, in the present embodiment, the exhaust gas pipe 36B is connected to the valve V, and the outlet side end edge of the exhaust gas pipe 36B is connected to the first gas passage 27, whereby the generated gas is processed in the desulfurization tower 10 and the gas holder 11 can be stored.

  In the acid generation tank 3, by opening the valve V rapidly, the pressurized waste water in the container is opened to atmospheric pressure, and the gas dissolved in the liquid in a pressurized state is turned into fine bubbles. The fine bubbles adhere to the aggregated floc and float the aggregated floc, and the oil and fat component is adsorbed by the aggregated floc during the ascent. For this reason, the floc which adsorb | sucked the fats and oils component accumulates in the upper interface vicinity of a container, and an adsorption | suction floc and isolation | separation water are isolate | separated by isolate | separating this floc from a liquid component. Thus, the container of the acid generation tank 3 also serves as a floating separation tank, and the container and the valve V constitute a floating separation means.

  In order to satisfactorily perform flotation separation in the flotation separation step, it is preferable that the acid generation step is performed under the conditions of a hydraulic residence time (HRT) <5 days and a temperature of 20 ° C. or higher.

  A floating sludge pipe 36 is connected to one end face of the pressure vessel, and the adsorbed floc is sent to the methane fermentation tank 8 via the floating sludge pipe 36. The adsorbed floc is anaerobically digested in the methane fermentation tank 8 in which the floating methane fermentation bacteria are held, and the microbial gas containing the generated methane gas is sent to the desulfurization tower 10 via the second gas path 37. The microorganism-generated gas contains hydrogen sulfide generated in the methane fermentation process, and the desulfurized gas from which hydrogen sulfide has been removed by being treated in the desulfurization tower 10 is sent to the gas holder 11 via the desulfurization gas passage 28. It is stored in the gas holder 11.

  The fermentation residue (digested sludge) in the methane fermentation tank 8 is supplied to the sludge dehydrator 9 through the digested sludge pipe 38 and dehydrated. The desorbed liquid generated in the dehydration process is returned to the raw water storage tank 1 through the desorbed liquid pipe 40. The dewatered cake from which the digested sludge has been dewatered is discharged out of the system from the dewatered sludge tube 39 and disposed of as waste.

On the other hand, the separated water separated from the adsorbed floc has an acid content, a reduced fat content, and a low SS concentration. Therefore, separated water is supplied from the separated water pipe 26 to the high-load methane production tank 5 to generate methane. In this embodiment, granule sludge in which methane-producing bacteria are granulated is held in the high-load methane production tank 5, and an upward sludge blanket (UASB) method with a high load of about 2 kg-CODcr / m ³ / d or more. Methane production is performed. However, the method of methane fermentation of separated water is not limited to this, and may be other methods such as membrane methane fermentation and anaerobic fluidized bed method.

  The microorganism-producing gas containing methane gas produced in the high-load methane production tank 5 is sent to the desulfurization tower 10 via the first gas passage 27. The microbial product gas sent to the desulfurization tower 10 is desulfurized and then stored in the gas holder 11 and sent from the gas pipe 29 to a boiler or the like and used as energy.

  Excess sludge generated from the high-load methane production tank 5 is fed to the methane fermentation tank 8 through the anaerobic surplus sludge pipe 30 as necessary, and is anaerobically digested together with the floating sludge. Thus, when surplus sludge (anaerobic surplus sludge) generated from the high-load methane production tank 5 containing a high concentration of methanogens is supplied to the methane fermentation tank 8, the methane fermentation tank 8 is inoculated with a high concentration of methanogens. Will do. For this reason, stabilization and efficiency improvement of the methane fermentation in the methane fermentation tank 8 can be achieved.

  On the other hand, the treated water flowing out from the high-load methane production tank 5 contains about several hundred mg / L of organic matter, and is therefore introduced into the post-treatment tank 6 through the anaerobic treated water pipe 32. Activated sludge is held in the post-treatment tank 6. In the post-treatment tank 6, the biological treatment is performed aerobically under conditions normally used while supplying an oxygen-containing gas such as air from the air diffuser such as the air diffuser 31.

  The activated sludge treated water obtained by such aerobic treatment is introduced into the sedimentation basin 7 from the activated sludge treated water pipe 33 and separated into solid and liquid. The liquid obtained in the sedimentation basin 7 is discharged out of the system from the treated water pipe 34 as treated water. The separated sludge is drawn out from the sludge pipe 35. A sludge return pipe 35A and an aerobic surplus sludge pipe 35B are branched from the sludge pipe 35. The sludge return pipe 35A is connected to the post-treatment tank 6, and a part of the separated sludge is returned to the post-treatment tank 6 from the sludge return pipe 35A. The aerobic surplus sludge pipe 35B is connected to the methane fermentation tank 8, and the remainder of the separated sludge is supplied to the methane fermentation tank 8, and methane-fermented together with the floating sludge and the like.

  In this processing apparatus 101, fats and oils are adsorbed by performing biological treatment in the acid generation tank 3 and generating a liquid (pressurized wastewater) in which gas is dissolved in a pressurized state, and releasing the pressurized wastewater to atmospheric pressure. The adsorbed floc can be levitated and separated. As described above, since the floating separation can be performed in the acid generation tank 3, the oil and fat can be floated and separated without providing a separate floating separation tank, and the processing apparatus 101 can be downsized. Moreover, in the processing apparatus 101, in the acid generation tank 3, since the fats and oils and SS of raw | natural water are solubilized and organically oxidized, the soluble COD density | concentration of pressurized wastewater can be raised. Moreover, since the floating sludge supplied to the methane fermentation tank 8 is also subjected to acid fermentation in advance, the treatment in the methane fermentation tank 8 can be stabilized and the organic matter decomposition efficiency can be improved.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a system diagram showing an embodiment of the method for treating fat and oil-containing wastewater and the treatment apparatus 102 according to the second embodiment of the present invention. The processing apparatus 102 is different from the processing apparatus 101 according to the first embodiment in the following three points.

  First, in the processing apparatus 102, the aerobic surplus sludge pipe 35B is not connected to the methane fermentation tank 8, but is connected to the agglomeration reaction tank 2 instead. The anaerobic surplus sludge pipe 30 is also connected to the agglomeration reaction tank 2 through the digested sludge branch pipe 38B described below, not the methane fermentation tank 8. Further, the digested sludge branch pipe 38B branches from the digested sludge pipe 38 and is connected to the agglomeration reaction tank 2.

  With this configuration, the aerobic surplus sludge generated in the post-treatment tank 6, the anaerobic surplus sludge generated from the high-load methane generation tank 5, and the digested sludge are fed to the agglomeration reaction tank 2 in the processing apparatus 102. These sludges supplied to the agglomeration reaction tank 2 are mixed with raw water, whereby oil in the raw water is adsorbed by these sludges. That is, since these sludges function as biological flocs that adsorb fats and oils, the required amount of flocculant is greatly reduced, or floating separation without flocculant addition becomes possible. Thus, in the processing apparatus 102, the three pipes of the aerobic surplus sludge pipe 35B, the anaerobic surplus sludge pipe 30, and the digested sludge branch pipe 38B constitute a sludge floc supply path.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a system diagram showing an embodiment of the method for treating fat and oil-containing wastewater and the treatment apparatus 103 according to the third embodiment of the present invention. The processing apparatus 103 is different from the processing apparatus 102 of the second embodiment in that the digested sludge branch pipe 38B is not provided, while the dehydrated sludge return pipe 39B branched from the dehydrated sludge pipe 39 is provided. . The anaerobic excess sludge pipe 30 is directly connected to the agglomeration reaction tank 2.

  In this processing apparatus 103, the digested sludge extracted from the methane fermentation tank 8 is dehydrated or concentrated by a sludge dehydrator (or sludge concentrator) 9, and then part or all of the dehydrated sludge or concentrated sludge is returned to the methane fermentation tank 8. . Thereby, the sludge density | concentration in the methane fermentation tank 8 can be raised, and the residence time (SRT) of the sludge in the methane fermentation tank 8 can be lengthened simultaneously. For this reason, the methane fermentation tank 8 can be operated with a high load, and the methane fermentation tank 8 can be downsized. The operating conditions of the methane fermentation tank 8 with such a configuration are as follows: the sludge concentration in the tank is 20000 mg / L or more, preferably 20000 to 100000 mg / L, the SRT is 15 days or more, preferably 15 to 40 days, The residence time (HRT) can be 20 days or less, preferably 3 to 20 days.

  The process shown in FIGS. 1-3 is an example of embodiment of this invention, Comprising: This invention is not limited to the process of illustration at all unless the summary is exceeded. For example, the separated water obtained in the levitation separation step is not limited to the combined use of the aerobic treatment and the high-load anaerobic treatment, and may be treated by other methods, or only one of the treatments.

  Moreover, in the processing apparatus 102 of FIG. 2, you may return only aerobic surplus sludge, anaerobic surplus sludge, and digested sludge to the aggregation reaction tank 2. FIG. For example, aerobic surplus sludge may be introduced into the methane fermentation tank 8 in the processing apparatus 102 of FIG. 2 and the processing apparatus 103 of FIG. Alternatively, the aerobic surplus sludge is returned to the flocculation reaction 2 and the anaerobic surplus sludge from the high-load methane production tank 5 is introduced into the methane fermentation tank 8 to increase the concentration of the methane producing bacteria in the methane fermentation tank 8. Also good. Furthermore, a part of the dewatered sludge from the sludge dewatering machine 9 may be returned to the agglomeration reaction tank 2 together with the digested sludge in the methane fermentation tank 8 or instead of the digested sludge. Also in this case, as a result, the sludge concentration in the methane fermentation tank 8 can be increased and high-load operation can be performed.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[Example 1]
The following water quality food factory wastewater (flow rate 430 m ³ / d) containing fats and oils as a poorly water-soluble substance was treated using the treatment apparatus 102 shown in FIG. The organic substance concentration is shown as BOD concentration, and the fat and oil concentration is shown as normal hexane extract concentration.
[Raw water quality]
BOD: 2300mg / L
SS: 653 mg / L
n-hexane extract: 170 mg / L

  This oil-containing wastewater has a relatively low fat concentration, and the composition ratio of sludge when the activated sludge process is performed without subjecting the separated water obtained after the pressure flotation treatment and the pressure flotation treatment to methane fermentation is 3: 4. (Pressurized flotation scum: excess sludge)

The specifications of each tank are as follows.
Acid production tank volume: 110 m ³
High load methane production tank volume: 210 m ³ (organic load: 10-15 kg-CODcr / m ³ / d)
Post-treatment tank volume: 150 m ³
Methane fermentation tank volume: 45 m ³ (organic load: 10-15 kg-CODcr / m ³ / d)

As a result, the amount of methane generated was 526 m ³ / d, the water content of the dehydrated cake was 85%, and the amount generated was 0.73 ton / d. Moreover, deterioration of the biological treatment, such as the reduction of the processing efficiency in the high-load methane production tank 5 and the occurrence of bulking in the post-treatment tank 6, was not recognized.

  Thus, according to the present invention, without providing a pressurized flotation tank, fats and oils that are difficult to biodegrade can be floated and separated, and the separated water can be methane-fermented with a high load such as the UASB method. For this reason, a processing apparatus can be simplified.

  INDUSTRIAL APPLICABILITY The present invention can be used for the treatment of organic matter-containing wastewater that treats fat-containing wastewater or the like under anaerobic conditions.

It is a schematic diagram of the wastewater treatment apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram of the wastewater treatment apparatus which concerns on 2nd Embodiment of this invention. It is a schematic diagram of the wastewater treatment apparatus which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water storage tank 2 Coagulation reaction tank 3 Acid production tank 5 High load methane fermentation 6 Post-treatment tank 7 Sedimentation tank 8 Methane fermentation tank 9 Sludge dewatering machine 10 Desulfurization tower 11 Gas holder 101-104 Wastewater processing equipment

Claims (8)

By introducing waste water containing poorly water-soluble substances and organic substances into a sealable container and anaerobically biotreating the floc in a coexisting state, the gas is pressurized to the waste water. A pressurized wastewater generation step for obtaining pressurized wastewater contained in
A levitation separation step of depressurizing the pressurized wastewater to float the adsorption floc adsorbed on the floc so that the poorly water-soluble substance is separated from the liquid to obtain the adsorption floc and separated water;
Wherein the post-processing of the separated water to the activated sludge process, only containing, treatment method of the waste water supplied to the sealed container sludge generated in the post-processing step as the flock. By introducing waste water containing poorly water-soluble substances and organic substances into a sealable container and anaerobically biotreating the floc in a coexisting state, the gas is pressurized to the waste water. A pressurized wastewater generation step for obtaining pressurized wastewater contained in
A levitation separation step of depressurizing the pressurized wastewater to float the adsorption floc adsorbed on the floc so that the poorly water-soluble substance is separated from the liquid to obtain the adsorption floc and separated water;
A methane production step of introducing the separated water into a methane production tank and performing methane fermentation;
A post-treatment step of treating the treated water obtained in the methane generation step with an activated sludge,
Supplying the sludge generated in the post-treatment step to the sealed container as the floc,
A method for treating wastewater, wherein acid production by acidogenic bacteria is performed as biological treatment in the pressurized wastewater production step. The wastewater treatment method according to claim 1 or 2 , wherein the poorly water-soluble substance is oil. The wastewater treatment method according to any one of claims 1 to 3, further comprising a coagulation reaction step in which a flocculant is added to the wastewater to form the floc before the pressurized wastewater generation step. By providing a sealable container into which waste water containing a poorly water-soluble substance and an organic substance is introduced, and in the container, the waste water is anaerobically biologically treated to generate gas in a state where floc coexists. A pressurized wastewater generating means for obtaining pressurized wastewater containing the gas in a pressurized state in the wastewater;
A levitation separation means for depressurizing the pressurized wastewater to float the adsorption flocs adsorbed by the flocs on the flocs so as to separate the liquids from the liquid components and obtain the adsorption flocs and separated water;
A post-treatment tank for introducing activated water sludge by introducing the separated water;
A sludge floc supply path for supplying the sludge generated in the post-treatment tank to the container as the flock;
Wastewater treatment equipment including. By providing a sealable container into which waste water containing a poorly water-soluble substance and an organic substance is introduced, and in the container, the waste water is anaerobically biologically treated to generate gas in a state where floc coexists. A pressurized wastewater generating means for obtaining pressurized wastewater containing the gas in a pressurized state in the wastewater;
A levitation separation means for depressurizing the pressurized wastewater to float the adsorption flocs adsorbed by the flocs on the flocs so as to separate the liquids from the liquid components and obtain the adsorption flocs and separated water;
A methane production tank for introducing methane fermentation by introducing the separated water;
A post-treatment tank that introduces treated water flowing out of the methane generation tank to treat activated sludge;
A sludge floc supply path for supplying the sludge generated in the post-treatment tank to the container as the floc,
The said container hold | maintains an acid production microbe, The wastewater processing apparatus comprised so that acid generation might be performed. The waste water treatment apparatus according to claim 5 or 6, wherein the floating separation means includes an openable / closable valve provided in the container. An agglomeration reaction tank in which a flocculant is added to the wastewater to form the floc;
The wastewater treatment apparatus according to any one of claims 5 to 7 , further comprising a coagulation floc supply path for supplying the floc generated in front of the coagulation reaction tank to the container.

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