JP6216253B2 - Method and apparatus for treating oil-containing wastewater - Google Patents

Description

  The present invention relates to a method and apparatus for treating oil-containing wastewater.

  Wastewater containing a large amount of oil and fat, such as food factory wastewater and domestic wastewater, causes various problems such as blockage of sewage piping. Conventionally, for example, those described in Patent Documents 1 and 2 have been proposed as treatment methods and treatment apparatuses for wastewater containing such fats and oils.

  In Patent Document 1, a chemical is added to and mixed with wastewater, and then floats by pressure or floats by microbubbles generated by a microbubble generator, then aeration using microbes, and sludge is separated or separated by membrane. In the wastewater treatment facility that purifies the pollutants in the wastewater by separating and removing the sludge from the mixed solution of treated water and sludge that has been aerated by solid-liquid separation treatment, etc. The waste water treatment method to be added to is described. In addition, it is described that a simple method can reduce the cost of chemicals for floating separation treatment with fine bubbles and avoid the problem of bad odor.

  Patent Document 2 states that "in order to treat activated sludge with pollutants in raw water, 1 to 30 parts, preferably 3 to 15 parts of the returned sludge (reactive sludge) is mixed and stirred in advance for 100 parts of raw water, and then the reactive sludge is added. Concentrated and separated by pressure flotation to obtain sludge (adsorption-concentration reaction sludge) containing 0.5% or more, preferably 2% or more of solids and treated raw water, which is combined with the returned sludge in the activated sludge aeration tank. After aeration treatment, solid-liquid separation is performed to obtain final effluent water and return sludge.Adsorption-concentration reaction sludge is anaerobically and aerobically digested in a thick sludge digester, and the polluted material adsorbed by the reaction sludge is microbially decomposed, The digested sludge is obtained, and an activated sludge treatment method in which the digested sludge is extracted and removed as surplus sludge is described. And, “Due to the efficient digestion of microorganisms by thick sludge digestion and the amount of undegraded substances is small, the digestion of sludge progresses, so the amount of generated sludge solids is small, and the amount of flocculant consumed is stable and stable for coagulation dehydration. Since good agglomeration is obtained, the dewatering efficiency of the dehydrator is increased, and since the water content of the obtained dewatered cake is low, not only the amount of the dewatered cake is small but also it is difficult to rot, so there are few bad odors and less work environment problems. Is described.

JP 2012-115820 A JP-A-6-315695

However, in the conventional method, a large amount of excess sludge and the like are generated. For example, Patent Document 1 describes that in FIG. 1 and the like, floating separation is performed and oil is discharged out of the system. Further, Patent Document 2 describes that activated sludge with less offensive odor can be obtained by dehydrating with a dehydrator.
Further, in the conventional method, it is difficult to decompose the fat and oil contained in the wastewater in a short time. For example, the method described in Patent Document 2 is a method in which anaerobic digestion and aerobic digestion are combined, and processing time of about 30 to 60 days is usually required even with only anaerobic digestion.
Furthermore, in the conventional method, oil residue is easily generated in the process. An example of the oil residue is an oil ball. Since the oil residue was difficult to decompose, the decomposition process took a very long time.

An object of the present invention is to solve the above problems.
That is, the objective of this invention is providing the processing method and processing apparatus of fats and oils containing waste water which can decompose | disassemble fats and oils in a short time, and are hard to produce excess sludge.

The present inventor has intensively studied to solve the above-described problems and completed the present invention.
The present invention includes the following (1) to (10).
(1) An anaerobic treatment step of performing anaerobic treatment on fat-containing wastewater to discharge anaerobic treated water;
An aerobic treatment step of applying an aerobic treatment to the anaerobic treated water;
A method for treating fat-containing wastewater, comprising: a sludge returning step of supplying the sludge generated in the aerobic treatment step to the fat-containing wastewater.
(2) Furthermore, the oil and fat-containing wastewater is subjected to a concentration treatment to obtain a concentrate and separated water,
The anaerobic treatment step is a step of subjecting the concentrate to an anaerobic treatment,
The method for treating oil-containing wastewater according to (1), wherein the sludge returning step is a step of supplying the sludge to the oil-containing wastewater and / or the concentrate.
(3) Furthermore, it comprises a dispersion step of obtaining a dispersion-treated water by subjecting the fat and oil-containing wastewater and / or the concentrate to a dispersion treatment,
The anaerobic treatment step is a step of subjecting the dispersion treated water to an anaerobic treatment,
The sludge returning step is the step of supplying the sludge to at least one selected from the group consisting of the oil and fat-containing wastewater, the concentrate, and the dispersion-treated water, as described in (1) or (2) above. Treatment method for oil-containing wastewater.
(4) In the dispersion step, the oil-and-fat residue generated in the anaerobic treatment step and / or the aerobic treatment step is subjected to a dispersion treatment together with the oil-containing wastewater and / or the concentrate to obtain the dispersion-treated water. The processing method of the fat-and-oil containing waste water as described in said (3) which is a process.
(5) The method for treating oil-containing wastewater according to any one of (1) to (4), wherein the aerobic treatment in the aerobic treatment step includes activated sludge treatment.
(6) anaerobic treatment means for performing anaerobic treatment on the fat-containing wastewater and discharging anaerobic treated water;
An aerobic treatment means for applying an aerobic treatment to the anaerobic treated water;
An apparatus for treating oil-containing wastewater, comprising: sludge returning means for supplying sludge generated in the aerobic treatment means to the oil-containing wastewater.
(7) Furthermore, it has a concentration means for obtaining a concentrate and separated water by performing a concentration treatment on the oil-containing wastewater,
The anaerobic treatment means is means for subjecting the concentrate to anaerobic treatment,
The processing apparatus for oil-containing wastewater according to (6), wherein the sludge returning means is means for supplying the sludge to the oil-containing wastewater and / or the concentrate.
(8) Further, the oil-containing wastewater and / or the concentrate is subjected to a dispersion treatment to obtain dispersion treated water,
The anaerobic treatment means is means for subjecting the dispersed treated water to anaerobic treatment,
(6) or (7), wherein the sludge return means is means for supplying the sludge to at least one selected from the group consisting of the oil-containing wastewater, the concentrate, and the dispersion-treated water. Oil and fat-containing wastewater treatment equipment.
(9) The dispersion means applies the dispersion means together with the oil-containing wastewater and / or the concentrate to the oil residue generated in the anaerobic treatment means and / or the aerobic treatment means to obtain the dispersed treated water. The processing apparatus of fat-and-oil containing waste water as described in said (8) which is a means.
(10) The apparatus for treating oil-containing wastewater according to any one of (6) to (9), wherein the aerobic treatment in the aerobic treatment means includes activated sludge treatment.

  According to the present invention, it is possible to provide a method and an apparatus for treating oil-containing wastewater that can decompose oils and fats in a short time and hardly generate excess sludge.

It is a conceptual diagram for demonstrating the apparatus of this invention. It is a conceptual diagram for demonstrating the suitable aspect of the apparatus of this invention. It is the schematic which shows the suitable aspect of the apparatus of this invention used in the Example. It is another schematic diagram which shows the suitable aspect of the apparatus of this invention used in the Example.

The present invention will be described.
The present invention provides an anaerobic treatment step for performing anaerobic treatment on oil-containing wastewater to discharge anaerobic treatment water, an aerobic treatment step for subjecting the anaerobic treatment water to an aerobic treatment, and the aerobic treatment step. And a sludge returning step of supplying the generated sludge to the fat-containing wastewater. Hereinafter, such a processing method is also referred to as a “method of the present invention”.
Further, the present invention provides an anaerobic treatment means for performing anaerobic treatment on oil-containing wastewater to discharge anaerobic treated water, an aerobic treatment means for subjecting the anaerobic treated water to an aerobic treatment, and the aerobic treatment. And a sludge returning means for supplying the sludge generated in the means to the fat and oil containing wastewater. Hereinafter, such a processing apparatus is also referred to as “the apparatus of the present invention”.
The method of the present invention is preferably performed using the apparatus of the present invention.
In the following, simply referring to “the present invention” shall mean both the method of the present invention and the apparatus of the present invention.

The present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an apparatus of the present invention.
In FIG. 1, an apparatus 1 according to the present invention includes an anaerobic treatment means 3 that performs anaerobic treatment on the fat-containing wastewater 2 and discharges the anaerobic treated water 4, and an anaerobic treatment on the anaerobic treated water 4. Aerobic treatment means 5 for discharging 7 and sludge return means 9 for supplying the sludge 8 generated in the aerobic treatment means 5 to the oil-containing wastewater 2.

<Oil containing wastewater>
The fat and oil containing waste water which is a process target object of this invention is demonstrated.
In the present invention, the fat and oil-containing waste water means water containing fat and oil. As the fat and oil-containing wastewater, wastewater mainly containing animal and vegetable oils and fats (triglycerides and partially decomposed products thereof) as the fat and oil can be mentioned. Specific examples include wastewater discharged from food factories and kitchens and domestic wastewater. The oil and fat-containing wastewater may further contain components other than the oil and fat content (for example, other organic substances and nitrogen components (ammonia nitrogen, organic nitrogen, etc.)).

In the present invention, the fat and oil-containing wastewater may have a lower limit of hexane extract concentration of 30 mg / L, preferably 50 mg / L, more preferably 100 mg / L, and an upper limit of 50,000 mg / L, preferably 30,000 mg. / L, more preferably 10,000 mg / L.
Here, the hexane extract concentration of the fat and oil-containing wastewater means a value obtained by measurement based on a factory wastewater test method (JIS K01024 24).
In the following description, the hexane extract concentration means a value obtained by measurement by such a method.

  In this invention, the anaerobic process can be given to what pretreated the fat-and-oils containing waste_water | drain. Therefore, what pre-processed to fat and oil containing wastewater shall correspond to fat and oil containing wastewater in this invention. As one aspect | mode of the fat-and-oils containing waste_water | drain in this invention, the dispersion process water obtained by giving the dispersion | distribution processing to the concentrate obtained by giving a concentration process to the fat-and-fat containing waste water and a fat-and-oil containing waste water is mention | raise | lifted, for example.

<Anaerobic treatment means, anaerobic treatment process>
The anaerobic treatment means 3 included in the apparatus 1 of the present invention will be described.
Anaerobic treatment means 3 performs anaerobic treatment on fat-and-water containing waste water 2 and discharges anaerobic treated water 4.

An anaerobic process is demonstrated.
In the present invention, the anaerobic treatment refers to a group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria in anaerobic environment without oxygen or in a microaerobic environment where oxygen is in a trace amount. The process which makes at least 1 chosen from act on the fats and oils contained in fats and oils containing waste water is meant.
Therefore, the anaerobic treatment in the present invention may be a conventionally known anaerobic treatment or anaerobic digestion.
The conventionally known anaerobic treatment (anaerobic biological treatment) means a biological treatment method in which organic substances are decomposed into methane gas or carbon dioxide gas by metabolic action of anaerobic bacteria growing in an anaerobic environment without oxygen. Here, the decomposition path from organic matter to methane gas is considered to consist of three stages. Specifically, the first stage of solubilization and low molecular weight hydrolysis of organic substances, and then the low molecular weight substance. It is considered that it consists of three stages: a second stage in which volatile fatty acids and alcohols are produced by acid fermentation, and finally a third stage in which methane gas is produced from acetic acid or hydrogen and carbon dioxide.

Further, at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria in anaerobic environment without oxygen or in a microaerobic environment where oxygen is a trace amount By acting on the fats and oils contained in the fat and oil-containing wastewater, the emulsification of fats and oils is mainly promoted by metabolites such as biosurfactants produced by these bacteria and / or partially decomposed by enzymes such as lipases. Thus, in principle, the treatment may not involve generation of gas (methane gas, carbon dioxide gas, etc.) accompanying decomposition by the methanogen that is an anaerobic bacterium.
Hereinafter, such processing is also referred to as “semi-anaerobic processing”.

Since the semi-anaerobic treatment does not include a decomposition reaction (methane gas generation reaction) corresponding to the third stage in the conventional anaerobic treatment in principle, no methane gas is generated. Further, the inventor presumes that the decomposition reaction (acid fermentation) corresponding to the second stage is not substantially included. Furthermore, there is a possibility that the decomposition reaction (hydrolysis) corresponding to the first stage proceeds at least for a part of the oil and fat.
The semi-anaerobic treatment does not include conventional anaerobic digestion (for example, anaerobic digestion described in Patent Document 2).

  The anaerobic treatment in the present invention can be performed, for example, by adjusting conditions (time, pH, temperature, etc.) that cause the anaerobic bacteria, microaerobic bacteria, and the like to act on the fat-and-water containing waste water 2.

  In the anaerobic treatment, the lower limit of the time during which at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria is allowed to act on the oil and fat-containing wastewater 2 is 20 hours. Preferably it is 2 days, more preferably 3 days. The upper limit of this time is preferably 15 days, and more preferably 10 days.

  As will be described later, when two or more stages of anaerobic treatment are performed, the total treatment time in each stage is such that the fat-containing wastewater 2 contains anaerobic bacteria, facultative anaerobic bacteria, and microaerobic bacteria. And at least one selected from the group consisting of aerobic bacteria.

  The anaerobic treatment is preferably performed at a pH of 7.2 or higher for the fat-and-oil-containing wastewater 2 (when a reaction tank is used in the anaerobic treatment means 3, the contents of the tank). Further, this pH is preferably set to 11.0 or less, more preferably 8.8 or less.

  The anaerobic treatment is preferably performed at a temperature of 20 ° C. or higher, and more preferably 30 ° C. or higher, when the fat-and-oil-containing wastewater 2 (when a reaction tank is used in the anaerobic treatment means 3, the contents of the tank). Moreover, it is preferable to perform this temperature as 58 degrees C or less, and it is more preferable to carry out as 47 degrees C or less.

  The anaerobic treatment is preferably carried out by adding sulfate ions to the fat and oil-containing wastewater 2. Moreover, it is preferable that the density | concentration of the sulfate ion in the fat and oil containing waste water 2 shall be 10-3,000 mg / L, It is more preferable to set it as 50-2,000 mg / L, It is further more preferable to set it as 100-1000 mg / L. .

  Moreover, when anaerobic bacteria and facultative anaerobic bacteria are made to act on the fat-and-oil containing waste water 2 and anaerobic treatment is performed, the fat-and-oil containing waste water 2 (the tank contents when the reaction tank is used in the anaerobic treatment means 3). An anaerobic treatment is performed by adjusting the redox potential to be preferably −200 mV or less, more preferably −300 mV or less.

  In the present invention, the oxidation-reduction potential means a value obtained by measurement by an ORP electrode method using a platinum electrode.

  The hexane extract concentration acceptable for the oil-containing wastewater 2 in the anaerobic treatment is preferably 30 to 30,000 mg / L, more preferably 30 to 20,000 mg / L, and more preferably 30 to 10,000 mg / L. More preferably, L is used.

  When the present invention is performed by semi-anaerobic treatment, it is preferably performed under the following conditions. This is because emulsification of fats and oils by metabolites such as biosurfactants and / or partial decomposition by enzymes such as lipase tends to proceed. Semi-anaerobic treatment is, for example, conditions (time, pH, temperature) that cause at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria to the oil-containing wastewater 2. Etc.).

  In the semi-anaerobic treatment, the lower limit of the time during which at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria is allowed to act on the oil-containing wastewater 2 is 20 hours. Is preferably 2 days, more preferably 3 days. The upper limit of this time is preferably 15 days, and more preferably 10 days. Since the treatment time in conventionally known anaerobic digestion is about 30 to 60 days, the semi-anaerobic treatment is preferable because it can be made shorter.

  Moreover, it is preferable that semi-anaerobic treatment is performed by setting the pH of the oil-and-fat-containing wastewater 2 (when a reaction vessel is used in the anaerobic treatment means 3) to pH 7.2 or more. Further, this pH is preferably set to 11.0 or less, more preferably 8.8 or less.

  The semi-anaerobic treatment is preferably performed at a temperature of 20 ° C. or higher, and more preferably at 30 ° C. or higher, when the fat and oil-containing wastewater 2 (when the reaction tank is used in the anaerobic treatment means 3). preferable. Moreover, it is preferable to perform this temperature as 58 degrees C or less, and it is more preferable to carry out as 47 degrees C or less.

  Moreover, it is preferable to perform a semi-anaerobic process by making the fat-and-oil containing waste water 2 contain a sulfate ion. Moreover, it is preferable to make the density | concentration of the sulfate ion in the fat-and-oils containing waste water 2 into 10-3,000 mg / L, It is more preferable to set it as 50-2,000 mg / L, It is set as 100-1,000 mg / L. Further preferred.

  When a semi-aerobic treatment is performed by causing microaerobic bacteria and / or aerobic bacteria to act on the oil-containing wastewater 2, for example, a limited oxygen supply different from the conventionally known aeration treatment is used for the oil-containing wastewater 2 (anaerobic). When using a reaction tank in the processing means 3, it is preferable to carry out with respect to the tank contents). At this time, the oxidation-reduction potential of the fat and oil-containing wastewater 2 (when the reaction tank is used in the anaerobic treatment means 3) is +50 mV or less, more preferably −50 mV or less, and further preferably −50 to −250 mV. It is preferable to adjust so that a semi-anaerobic treatment is performed.

  The anaerobic treatment means 3 of the apparatus 1 of the present invention is a means capable of discharging the anaerobic treated water 4 by applying the anaerobic treatment as described above (preferably semi-anaerobic treatment) to the oil-containing wastewater 2. If there is no particular limitation. For example, the oil and fat-containing wastewater 2 is received in a sealed container having anaerobic bacteria that live in an anaerobic environment without oxygen, and the anaerobic treated water 4 is discharged by causing the anaerobic bacteria to act on this. Can be mentioned. In addition, for example, a container having at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria living in a microaerobic environment with a small amount of oxygen. Then, the oil-containing wastewater 2 is received inside, and at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria is allowed to act on this, and anaerobic treated water 4 is discharged. Whatever container is used, it is preferable to have a device capable of stirring the inside thereof.

  As the anaerobic treatment means 3, an apparatus that performs a conventionally known treatment such as an anaerobic fixed bed method, anaerobic fluidized bed method, UASB method, EGSB method, or the like can be used. When semi-anaerobic treatment is performed as anaerobic treatment, as a general rule, treatment is performed under conditions where decomposition by methane producers (methane fermentation) does not proceed, such as a gas holder for storing methane gas, a desulfurization treatment device, etc. Ancillary facilities are not necessary in principle.

The anaerobic treatment means 3 further includes means capable of adjusting the pH, temperature, and oxidation-reduction potential of the oil-and-fat-containing wastewater 2 (when the reaction tank is used in the anaerobic treatment means 3, the contents of the tank) as described above. Preferably there is. The pH and temperature can be adjusted by known acid or alkali addition means or heating means. The oxidation-reduction potential can be adjusted by performing a semi-anaerobic treatment while blowing an appropriate amount of air to the oil-containing wastewater 2 (in the case of using a reaction tank in the anaerobic treatment means 3, the contents of the tank).
Moreover, as mentioned above, when using a reaction tank in the fat-and-oil containing waste water 2 or the anaerobic processing means 3, it is preferable to have a means which can add a sulfate ion to the tank contents. Sulfate ions can be added by known addition means.

The anaerobic treatment means 3 is preferably one that performs two or more stages of anaerobic treatment.
Here, the two-stage anaerobic treatment means that the anaerobic treatment is performed twice. For example, the airtight container is divided into two parts, a front part and a rear part, and after the anaerobic treatment is performed on the oil-containing drainage 2 at the front part, an anaerobic treatment is further performed at the rear part. Moreover, for example, after using two apparatuses and performing anaerobic treatment on the fat-and-oil containing waste water 2 by the first apparatus, an anaerobic process is further performed by the second apparatus.
The anaerobic processing means 3 may be an embodiment that performs anaerobic processing three or more times.
When the oil-and-fat-containing wastewater 2 is subjected to two or more anaerobic treatments in this manner, the aerobic treatment means 5 is further applied to the obtained anaerobic treatment water 4 to obtain treated water 7 with better water quality. It is.

  When the anaerobic treatment means 3 performs the anaerobic treatment on the oil-and-fat-containing wastewater 2, it is difficult for oil-and-fat residues to be generated. Even if it occurs, the amount is much less than that of the conventional method. When the oil residue is generated, it is preferable to treat the oil residue by a dispersing means described later.

It is preferable that the anaerobic treatment means 3 is configured to receive the return sludge generated in the aerobic treatment means 5. This is because when the returned sludge is received and treated together with the oil-and-fat containing waste water 2, treated water having better water quality can be obtained by further applying the aerobic treatment means 5 to the obtained anaerobic treated water 4.
The anaerobic treatment step provided in the method of the present invention can be performed by the anaerobic treatment means 3 as described above.

<Aerobic treatment means, aerobic treatment process>
The aerobic processing means 5 included in the apparatus 1 of the present invention will be described. The aerobic treatment means 5 performs an aerobic treatment on the anaerobic treated water 4 and discharges the treated water 7 and the sludge 8.

  The aerobic process will be described. In the present invention, the aerobic treatment means a treatment in which microorganisms mainly composed of aerobic bacteria that live in an aerobic environment where oxygen is present are decomposed by acting on anaerobic treated water.

  As the aerobic treatment of the present invention, for example, a conventionally known aerobic biological treatment can be applied. Specifically, the process which receives the anaerobic treated water 4 in a tank and aerates while stirring is exemplified. More specifically, known floating biological treatment methods (batch activated sludge method, continuous activated sludge method, etc.) and biofilm treatment methods (rotating disc method, aerobic filter bed method, fluidized bed method, etc.) Illustrated.

  Moreover, it is preferable that an aerobic process contains multiple types of process. For example, it is preferable to apply the fluidized bed method after applying the continuous activated sludge method to the anaerobic treated water 4. Moreover, it is preferable that it is the process which applies a continuous activated sludge method after performing an aeration process to the anaerobic treated water 4. FIG. Further, a denitrification step may be introduced into the treatment process.

  When the aerobic treatment includes a plurality of types of treatment, it is preferable to include a conventionally known activated sludge treatment as one of them. This is because in such a case, the purity of the treated water 7 finally obtained is further increased, and the treated water 7 having a hexane extract concentration that satisfies the sewage discharge standard value defined in the Sewerage Law can be obtained.

  The aerobic treatment in the present invention can be performed, for example, by adjusting conditions (time, pH, temperature, etc.) that cause aerobic bacteria or the like to act on the anaerobic treated water 4.

In the aerobic treatment, the lower limit of the time for aerobic bacteria to act on the anaerobic treated water 4 is preferably 3 hours, more preferably 3 days, and even more preferably 4 days. The upper limit of this time is preferably 14 days, and more preferably 7 days. This is because if the time for causing the aerobic bacteria to act on the anaerobic treated water 4 is within such a range, the treated water 7 with higher cleanliness can be obtained.
As will be described later, when two or more aerobic treatments are performed, the total treatment time in each step corresponds to the time for aerobic bacteria to act on the anaerobic treated water 4 as described above. .

  The aerobic treatment is preferably carried out at a pH of 7.2 or more, more preferably 7.5 or more, when the anaerobic treated water 4 (when the reaction vessel is used in the aerobic treatment means 5, the contents of the vessel). preferable. The pH is preferably set to 11.0 or less, more preferably 9.0 or less. This is because if the anaerobic treated water 4 is subjected to an aerobic treatment at such a pH in the range, treated water 7 having a higher cleanliness can be obtained.

  The aerobic treatment is preferably carried out at a temperature of 20 ° C. or more, more preferably 30 ° C. or more, when the temperature of the anaerobic treated water 4 (when a reaction vessel is used in the aerobic treatment means 5, the contents of the vessel). Moreover, it is preferable to perform this temperature as 58 degrees C or less, and it is more preferable to carry out as 47 degrees C or less. This is because if the anaerobic treated water 4 is subjected to an aerobic treatment at a temperature in such a range, treated water 7 with higher cleanliness can be obtained.

The aerobic treatment is preferably carried out at a ratio of the mass of oil and fat to the mass of nitrogen atoms (nitrogen atom / oil and fat content) in the anaerobic treated water 4 being 0.05 or more, and 0.1 to 0.5. Is more preferable.
The aerobic treatment is preferably performed by setting the ratio of the mass of the fat and oil to the mass of phosphorus atoms (phosphorus / fat and fat content) in the anaerobic treated water 4 as 0.01 or more, and as 0.05 to 0.1. More preferred.
It is preferable to replenish nutrients such as a nitrogen source during the aerobic treatment so that the mass ratio of nitrogen, phosphorus and fats and oils is obtained.

  As will be described later, when the aerobic treatment means 5 performs two or more aerobic treatments, the first stage aerobic treatment has a dissolved oxygen amount (DO) in the treatment tank of 2 mg / L or less. Preferably, it is performed so that it may become 1.0 mg / L or less, and it is still more preferable to carry out so that it may become 0.6 mg / L or less. The amount of dissolved oxygen (DO) in the aerobic treatment tank after the second stage is preferably 1.0 mg / L or more, more preferably 2.0 mg / L or more, It is more preferable to carry out so that it may become 3.0 mg / L or more. This is because the treated water 7 having a higher cleanliness can be obtained. In addition, when the aerobic processing means 5 is 1 step | paragraph, it is preferable to carry out so that the amount of dissolved oxygen (DO) in a processing tank may be 1.0 mg / L or more, and it will carry out so that it may become 2.0 mg / L or more. More preferably, it is more preferable to carry out so that it may become 3.0 mg / L or more.

The aerobic treatment means 5 included in the apparatus 1 of the present invention is not particularly limited as long as it can apply the aerobic treatment as described above to the anaerobic treated water 4 and discharge the treated water 7 and the sludge 8. For example, an anaerobic treated water 4 is received in a container having an aerobic bacterium inhabiting in an aerobic environment where oxygen is present, and the treated water 7 is discharged by causing the aerobic bacterium to act on this. It is done. It is preferable to have a device capable of stirring the inside of such a container.
Conventional aerobic treatment means 5 such as floating biological treatment methods (batch activated sludge method, continuous activated sludge method, etc.) and biofilm treatment methods (rotating disc method, aerobic filter bed method, fluidized bed method, etc.) It is possible to use an apparatus that performs a known process.
Furthermore, as described above, it further has means capable of adjusting the pH, temperature, nitrogen, phosphorus, dissolved oxygen amount, etc. of the anaerobic treated water 4 (when the reaction tank is used in the aerobic treatment means 5, the contents of the tank). It is preferable. The pH and temperature can be adjusted by conventionally known acid and alkali addition means and heating means. Nitrogen or phosphorus can be adjusted using a conventionally known nitrogen source or phosphorus source replenishing means. The amount of dissolved oxygen can be adjusted by aeration stirring means.

It is preferable that the aerobic processing means 5 performs aerobic processing of two or more stages.
Here, the two-stage aerobic process means that the aerobic process is performed twice. For example, the container is divided into two parts, a front part and a rear part, and after the aerobic treatment is performed on the anaerobic treated water 4 at the front part, an aerobic treatment is further performed at the rear part. In addition, for example, there is an embodiment in which two apparatuses are used, and the anaerobic treatment water 4 is subjected to the aerobic treatment with the first apparatus and then subjected to the aerobic treatment with the second apparatus.
The aerobic processing means 5 may be an embodiment that performs aerobic processing three or more times.
This is because when two or more aerobic treatments are performed on the anaerobic treated water 4 in this way, treated water 7 having better water quality can be obtained.

In the aerobic treatment in the aerobic treatment means 5, bubbles may be generated from the surface of the treatment liquid during the treatment. When bubbles are generated, there is a possibility that sludge flows out from the reaction tank or the piping provided in the aerobic treatment means 5 may be blocked, which is not preferable. In such a case, it is preferable that the aerobic processing means 5 further includes a foam removing means for removing the foam.
Examples of the foam removing means include adding an antifoaming agent by an aerobic treatment. If an antifoaming agent is added, generation | occurrence | production of foam can be suppressed. As the antifoaming agent, it is preferable to use a nonionic surfactant antifoaming agent.

Further, as another bubble removing means, a structure capable of attaching the generated bubbles to the upper space of the liquid surface being processed can be used. When such a structure is installed in the upper space of the liquid surface being processed, the bubbles adhere to the surface of the structure in a film form, so that the bubbles can be separated from the liquid surface. And the processing speed of the fats and oils in an aerobic process can be improved. Examples of the structure include a unit in which sheet-like filters are arranged in the vertical direction.
It is preferable that the method of the present invention further includes a foam removing step that can be performed using such a foam removing means.

The anaerobic treatment step provided in the method of the present invention is preferably a step of subjecting the oil-containing wastewater to anaerobic treatment together with the foam separated in the foam removal step.
As described above, when a structure capable of adhering foam generated in the upper space of the liquid surface being treated is used as the foam removal means, the recovered foam is used for the oil-containing wastewater and / or anaerobic treatment means. By adding to the process, anaerobic treatment can be applied to the oil-containing wastewater together with the separated foam.
As another aspect, an anaerobic treatment can be performed on the oil-and-fat-containing wastewater together with the recovered bubbles by providing means for transferring the foam generated in the aerobic treatment step to the anaerobic treatment step.
In addition, for example, a reaction tank that performs an aerobic treatment has a sealed structure, and a reaction liquid (anaerobic treated water 4) that overflows from a reaction tank that performs an anaerobic treatment is introduced into the reaction tank that performs an aerobic treatment. Thus, the separated foam can be supplied to a reaction tank (semi-anaerobic treatment means 3) for performing anaerobic treatment, and the oil-containing wastewater can be subjected to anaerobic treatment together with the separated foam. In such a case, a reaction tank is formed in which a reaction liquid that overflows from the reaction tank that performs the anaerobic treatment and a bubble that is discharged together with the exhaust by aeration are formed, and at least a part of the foam is subjected to the anaerobic treatment. Can be supplied within. The bubbles supplied into the reaction tank that performs the anaerobic treatment disappear by the stirring flow in the reaction tank.

  When the aerobic treatment means 5 performs the aerobic treatment on the anaerobic treated water 4, it is difficult for oil and fat residues to be generated. Even if it occurs, the amount is much less than the conventional method. When the oil residue is generated, it is preferable to treat the oil residue by a dispersing means described later.

The aerobic treatment means 5 has a configuration capable of discharging the sludge 8 since it is stored inside.
The aerobic treatment means 5 preferably includes a solid-liquid separation means. In this case, the sludge 8 stored in the aerobic treatment means 5 can be discharged quickly. As described above, the aerobic treatment in the present invention preferably includes an activated sludge treatment. However, the activated sludge treatment is usually a treatment using an apparatus comprising an aeration tank and a settling tank, and the activated sludge is treated by the settling tank. Means for separating flocs by natural sedimentation. Thus, it is preferable that the aerobic treatment means 5 includes a solid-liquid separation means such as a sedimentation tank for performing activated sludge treatment. Of course, the aerobic treatment means 5 that does not include activated sludge treatment preferably includes a solid-liquid separation means.
The sludge 8 discharged from the aerobic treatment means 5 is used as return sludge and is added to the fat and oil containing waste water 2 by the sludge return means 9.
The aerobic treatment step provided in the method of the present invention can be performed by the aerobic treatment means 5 as described above.

<Sludge return means, sludge return process>
The sludge return means 9 which the apparatus 1 of this invention has is demonstrated. The sludge return means 9 is means for supplying the sludge 8 generated in the aerobic treatment means 5 to the oil-containing wastewater 2.
As the sludge return means 9, for example, a pipe is connected from the outlet of the sludge 8 in the aerobic treatment means 5 to a tank for storing the oil-containing wastewater 2 disposed in the previous stage of the anaerobic treatment means 3. The means to transfer 8 and add the sludge 8 to the fat and oil containing waste water 2 is illustrated.
The amount of return sludge added to the fat-and-oil containing waste water 2 by the sludge return means 9 is preferably such that the SS concentration after addition is 50 to 500 mg-SS / L.

  The present inventor has found that when the apparatus of the present invention has the sludge return means 9 for adding return sludge to the fat-and-oil containing drainage 2, oil and fat residues are hardly generated. Moreover, this inventor discovered that decomposition | disassembly of fats and oils became easier and the treated water 7 with a higher cleanliness was obtained.

  The method of the present invention further comprises a sludge return step for supplying the sludge 8 generated in the aerobic treatment step to the oil-containing wastewater 2, and the sludge 8 is treated together with the oil-containing wastewater 2 in the anaerobic treatment step. It is preferable. Such a sludge returning step can be performed by the sludge returning means 9.

  The apparatus of the present invention preferably has the anaerobic treatment means 3, the aerobic treatment means 5, and the sludge return means 9 as described above, and further has a concentration means and / or a dispersion means.

  The apparatus of the present invention having an anaerobic treatment means 3 and an aerobic treatment means 5, a plurality of sludge return means (11, 23, 26), and further comprising a concentration means 18 and a dispersion means 19. An example will be described with reference to FIG.

FIG. 2 is a schematic diagram showing a preferred embodiment (apparatus 10) of the apparatus of the present invention.
The apparatus 10 has an anaerobic treatment means 3 and an aerobic treatment means 5, and further has a sludge return means 11, a concentration means 18, a dispersion means 19, a sludge return means 23 and a sludge return means 26. Moreover, the apparatus 10 has a PAC addition means 12 for adding PAC (polyaluminum chloride) to the oil-containing wastewater 2 and an aggregation polymer addition means 13 for adding an aggregation polymer.
In the following, the device 10 will be described in detail with respect to differences from the device 1 of the present invention shown in FIG. In FIG. 2, the same reference numerals are given to the same components of the device 10 as those of the device 1 of the present invention shown in FIG.

The sludge return means 11 will be described. The sludge return means 11 is means for adding the return sludge 28 generated in the aerobic treatment means 5 to the fat and oil containing waste water 2.
As the sludge return means 11, for example, a return sludge 28 discharge port in the aerobic treatment means 5 is connected to a tank for storing the oil-containing wastewater 2 disposed in the preceding stage of the concentration means 18, and the return sludge is obtained by the action of a pump. A means for transferring 28 and adding the return sludge 28 to the oil-containing wastewater 2 is exemplified.
It is preferable that the addition amount of the return sludge to the fat-and-oil containing waste water 2 by the sludge return means 11 is an amount in which the SS concentration after the addition is 50 to 500 mg-SS / L.

The present inventor found that when the apparatus (apparatus 10) of the present invention has the sludge return means 11 for adding the return sludge to the fat and oil-containing wastewater 2, the oil and fat residue is hardly generated. Moreover, this inventor discovered that decomposition | disassembly of fats and oils became easier and the treated water 7 with a higher cleanliness was obtained. As will be described later, compared with the case where the return sludge is added by the sludge return means 23 in the dispersing means 19 or the case where the return sludge is added by the sludge return means 26 in the anaerobic treatment means 3, the previous stage of the concentration means 18. The present inventor has found that the addition of return sludge to the oil-containing wastewater 2 by the sludge return means 11 makes it easier for oil residue to be generated and further facilitates the decomposition of the oil and fat.
After the return sludge is added to the oil-containing wastewater 2, when the concentration means 18 such as a pressurized flotation tank is applied, the concentrate 21 (such as floss) is not a lump of fat and oil, but the fat and oil is adsorbed on the return sludge surface. Since it becomes a dispersed state, the inventor presumes that the reactivity in the subsequent anaerobic treatment is improved, the generation of oil residue is suppressed, and the oil and fat content is easily decomposed.

  The method of the present invention further includes a sludge return step for supplying the return sludge 28 generated in the aerobic treatment step to the oil-containing wastewater 2, and the return sludge 28 is supplied to the fat-containing wastewater 2 or in the anaerobic treatment step. It is preferable to treat this together with the concentrate 21 or the dispersion treated water 25 obtained by further processing. Such a sludge return process can be performed by the sludge return means 11.

The PAC addition unit 12 and the aggregate polymer addition unit 13 will be described.
A desired amount of PAC can be added to the fat and oil-containing wastewater 2 by the PAC addition means 12. Further, a desired amount of aggregated polymer can be added to the fat-and-oil-containing wastewater 2 by the aggregated polymer adding means 13. A cationic polymer or an anionic polymer can be used as the aggregation polymer. When PAC and / or agglomerated polymer is added to the fat-and-oil-containing wastewater 2, the cleanliness of the treated water 7 discharged from the apparatus 10 tends to increase. Moreover, when the apparatus of this invention is equipped with the concentration means 18, when PAC and / or agglomerated polymer are added to the fat-and-oils containing waste water 2, the separation efficiency will increase more in the concentration means 18, and the fat and oil concentration in the concentrate will tend to increase. There exists a tendency for the cleanliness of the treated water 7 discharged | emitted from the apparatus 10 to become high.

  Each of the PAC addition unit 12 and the aggregation polymer addition unit 13 stores the PAC or the aggregation polymer as a solution or a dispersion in a dedicated tank, and supplies the PAC or the aggregation polymer to the oil-containing wastewater 2 with a desired supply amount through a pipe by the action of a pump. What can do is illustrated.

When the apparatus 10 further includes a regulating tank, the PAC and / or the agglomerated polymer from the PAC addition unit 12 and / or the agglomerated polymer addition unit 13 is received and mixed with the oil-containing waste water 2 to obtain a desired discharge amount. Thus, it is preferable to discharge to a subsequent process such as the concentration means 18.
In addition, if the adjustment tank has a storage part which can store the fat and oil containing waste water 2, the form of the structure will not be specifically limited.

  The concentration means 18 will be described. The concentrating means 18 receives the fat / oil-containing wastewater 2 (which may contain return sludge, PAC or agglomerated polymer), concentrates the oil / fat content contained in the fat / oil-containing wastewater 2, and discharges it as a concentrate 21. It is means for discharging a portion other than 21 as separated water 22.

The concentrate 21 can be supplied to the dispersing means 19. The separation water 22 is configured to be supplied to the aerobic treatment process in the aerobic treatment means 5 or to the vicinity of the inlet or the outlet thereof.
When the aerobic treatment in the aerobic treatment means 5 includes the activated sludge treatment, it is preferable to supply the separation water 22 immediately before the activated sludge treatment, for example, near the inlet of the activated sludge tank.

It is preferable to obtain the concentrate 21 in which the concentration of the fat and oil contained in the fat and oil-containing waste water 2 is concentrated 10 times or more by the concentration means 18. The degree of concentration is preferably 40 to 50 times.
A pressure levitation tank is preferably used as the concentration means 18. A concentrate obtained by a flotation separation process using a pressurized flotation tank is also referred to as floss.

If the apparatus of the present invention has the concentration means 18, the anaerobic treatment means 3 is applied to the concentrate 21 containing the fat and oil contained in the oil-containing wastewater 2 at a high concentration, and the aerobic treatment means 5 is further applied. In the anaerobic treatment and the aerobic treatment, the concentration of microorganisms is increased, and the contact efficiency between the oil and fat and the microorganisms is increased, which is preferable because the decomposition rate is increased.
Moreover, compared with the case where an anaerobic process is performed with respect to the fat-and-oils containing waste water 2, the direction of performing the anaerobic process with respect to the concentrate 21 becomes remarkably small. Therefore, when a reaction vessel is used in the anaerobic treatment means 3, it is preferable because the treatment time (retention time) per volume of the reaction vessel can be increased.

  In the method of the present invention, the anaerobic treatment step is a step of subjecting the concentrate 21 to an anaerobic treatment after the fat-containing waste water 2 is concentrated to obtain the concentrate 21 and the separated water 22. preferable. Such concentration treatment can be performed by the concentration means 18.

  The dispersing means 19 will be described. The dispersion means 19 is a means for receiving the concentrate 21, stirring it, and discharging it as the dispersion treated water 25. Further, the dispersing means 19 is configured to receive the oil residue 24 and the return sludge from the sludge return means 23. Therefore, the dispersion means 19 receives the fat residue 24 and / or the return sludge 28 as necessary, stirs the concentrate 21 together with these, and discharges them as the dispersion treated water 25. As the dispersing means 19, for example, a structure having a storage section provided with a stirring device is exemplified.

The stirring in the dispersing means 19 is preferably physical stirring means such as mechanical stirring. In addition, mechanical stirring under alkaline pH conditions, mechanical stirring under high temperature conditions, mechanical stirring under the action of degrading enzymes such as lipase, mechanical stirring in the presence of surfactants such as emulsifiers, oxidizing agents such as ozone and chemical oxidizing agents It is more preferable that the mechanical stirring is performed under an environment because a good dispersion state can be obtained.
It is preferable that the apparatus of the present invention has the dispersing means 19 since it can be efficiently decomposed when an oil residue is generated. As the dispersion means 19, for example, a structure having a storage part provided with a stirring device inside is exemplified.

The method of the present invention further comprises a dispersion step of subjecting the oil-containing wastewater 2 and / or the concentrate 21 to a dispersion treatment to obtain a dispersion treatment water 25, and the anaerobic treatment step is an anaerobic treatment on the dispersion treatment water 25. It is preferable that it is the process of giving.
Moreover, such a dispersion | distribution process performs a dispersion | distribution process with the fat-and-oil containing waste water 2 and / or the concentrate 21 to the fat-and-oil residue 24 which generate | occur | produced in the said anaerobic treatment process and / or the said aerobic treatment process, and dispersion-treated water 25 It is preferable that it is the process of obtaining.
Such a dispersion step can be performed by the dispersion means 19 described above.

The sludge return means 23 will be described. The sludge return means 23 is means for adding the return sludge 28 generated in the aerobic treatment means 5 to the concentrate 21 in the dispersion means 19.
As the sludge return means 23, the thing similar to the above-mentioned sludge return means 11 is mentioned. For example, there is exemplified a means for connecting the return sludge 28 from the discharge port of the return sludge 28 in the aerobic treatment means 5 to the dispersing means 19 by piping, transferring the return sludge 28 by the action of a pump, and adding the return sludge 28 to the concentrate 21. The The amount of return sludge added to the concentrate 21 by the sludge return means 23 is preferably such that the SS concentration after addition is 500 to 5,000 mg-SS / L.

  The present inventors have found that when the apparatus (apparatus 10) of the present invention has the sludge return means 23 for adding the return sludge to the concentrate 21, it is difficult for oil and fat residues to be generated. Moreover, this inventor discovered that decomposition | disassembly of fats and oils became easier and the treated water 7 with a higher cleanliness was obtained. As will be described later, in comparison with the case where the return sludge is added by the sludge return means 26 in the anaerobic treatment means 3, the return sludge is added to the concentrate 21 by the sludge return means 23 in the dispersion means 19. The present inventor has found that the residue is less likely to be generated and that the oil and fat content is more easily decomposed.

  The method of the present invention further includes a sludge return step for supplying the return sludge 28 generated in the aerobic treatment step to the concentrate 21 which is an embodiment of the oil-containing wastewater 2, and the return sludge in the anaerobic treatment step. 28 is preferably treated with the concentrate 21 or the dispersion treated water 25 obtained by further processing the concentrate 21. Such a sludge returning step can be performed by the sludge returning means 23.

The anaerobic processing means 3 will be described. The anaerobic processing means 3 may be the same as that shown in FIG. Anaerobic treatment means 3 accepts dispersed treated water 25, performs anaerobic treatment, and discharges anaerobic treated water 4.
The anaerobic treatment means 3 is configured so that the sludge return means 26 can accept the return sludge. Further, as described above, when the oil / fat residue 24 is generated, the oil / fat residue 24 can be collected and supplied to the dispersing means 19.
The oil-and-fat residue can be collected, for example, by means of collecting the oil-and-fat residue floating on the water surface with a scraper and transferring it by human power or a conveyor. Also in the aerobic processing means 5, fat and oil residues can be collected by the same method.

The sludge return means 26 will be described. The sludge return means 26 is means for adding the return sludge 28 generated in the aerobic treatment means 5 to the concentrate 21 and / or the dispersion treated water 25 in the anaerobic treatment means 3.
As the sludge return means 26, the thing similar to the above-mentioned sludge return means 11 and the return sludge 23 is mentioned. For example, the return sludge 28 in the aerobic treatment means 5 is connected to the anaerobic treatment means 3 by piping, the return sludge 28 is transferred by the action of a pump, and the return sludge 28 is concentrated 21 and / or dispersed. A means for adding to the water 25 is exemplified.
The amount of return sludge added to the dispersion treated water 25 by the sludge return means 26 is preferably such an amount that the SS concentration after addition is 500 to 5,000 mg-SS / L.
The present inventor has found that when the apparatus (apparatus 10) of the present invention has the sludge return means 26 for adding the return sludge to the concentrate 21 and / or the dispersed treated water 25, oil residue is less likely to be generated. . Moreover, this inventor discovered that decomposition | disassembly of fats and oils became easier and the treated water 7 with a higher cleanliness was obtained.

  The method of the present invention further includes a sludge return step of supplying the return sludge 28 generated in the aerobic treatment step to the concentrate 21 and / or the dispersed treated water 25 which is one embodiment of the oil-containing wastewater 2, In the property treatment step, the return sludge 28 is preferably subjected to anaerobic treatment together with the concentrate 21 and / or the dispersion treated water 25. Such a sludge return process can be performed by the sludge return means 26.

  The aerobic processing means 5 will be described. The aerobic processing means 5 may be the same as that shown in FIG. The aerobic treatment means 5 receives the anaerobic treated water 4, performs aerobic treatment by the action of aerobic bacteria, and discharges the treated water 7. The aerobic treatment means 5 is configured to receive the separated water 22. Further, as described above, when the oil / fat residue 24 is generated, the oil / fat residue 24 can be collected and supplied to the dispersing means 19.

Further, the aerobic treatment means 5 preferably includes a solid-liquid separation means such as a precipitation tank.
The solid-liquid separation means is configured to discharge the precipitate as the return sludge 28 and discharge the supernatant as the treated water 7.
The return sludge 28 discharged from the aerobic treatment means 5 is configured so as to be supplied as the return sludge to the fat and oil-containing waste water 2, the dispersion means 19 or the anaerobic treatment means 3.
It is preferable that the aerobic treatment means 5 includes a solid-liquid separation means because treated water 7 with higher cleanliness can be obtained.

  Moreover, when the aerobic processing means 5 performs an aerobic process of two or more stages, it is preferable to use the sludge generated in the process of the previous stage as the return sludge. Moreover, it is preferable to add and use the sludge obtained here to the fat-and-oils containing waste water 2 as return sludge before processing with the concentration means 18. For example, when the aerobic treatment means 5 is an embodiment having an aerobic tank, an activated sludge tank, and a sedimentation tank in this order, when sludge generated in the aerobic tank on the front stage is used as the return sludge, Compared with the case where sludge generated in a certain sedimentation tank is used as return sludge, treated water 7 having a higher cleanliness can be obtained, which is preferable.

  The present invention will be described using examples. The present invention is not limited to the following examples.

  The experimental apparatus used in the examples will be described with reference to FIGS. In the examples, the experimental device 30 (FIG. 3) or the experimental device 90 (FIG. 4) described below was used.

  The experimental apparatus 30 will be described. The experimental apparatus 30 shown in FIG. 3 has an adjustment tank 32, a pressurized levitation tank 34, a dispersion tank 36, an anaerobic tank 38, an aerobic tank 40, an activated sludge tank 42, and a sedimentation tank 44. The experimental apparatus 30 has sludge return means 52, 62, 70, 74.

The pressurized levitation tank 34 corresponds to a concentration means that the apparatus of the present invention preferably has.
The dispersion tank 36 corresponds to a dispersion means that the apparatus of the present invention preferably has.
The anaerobic tank 38 corresponds to an anaerobic treatment means included in the apparatus of the present invention.
The aerobic tank 40, the activated sludge tank 42, and the settling tank 44 correspond to the aerobic treatment means of the apparatus of the present invention.
The sludge return means 52, 62, and 70 correspond to the sludge return means that the apparatus of the present invention has.

The adjustment tank 32 stores the oil-containing wastewater 50, and the experimental apparatus 30 uses a structure having a storage part. The oil and fat-containing wastewater 50 is received and stored in the adjustment tank 32 and can be supplied to the pressurized levitation tank 34 with a desired supply amount.
Further, the sludge return means 52, the PAC addition means 54, and the agglomerated polymer addition means 56 are configured so that the return sludge, the PAC, and the agglomerated polymer can be supplied to the inside of the adjustment tank 32. Specifically, each of the PAC and the agglomerated polymer is stored as a solution or a dispersion in a dedicated tank, and can be supplied to the adjustment tank 32 with a desired supply amount through a pipe by the action of a pump. Specifically, the sludge return means 52 connects the return sludge 76 and the sludge 80 in the aerobic tank 40 and the sedimentation tank 44 to the adjustment tank 32 by piping, and returns the sludge 76 and the sludge 80 by the action of the pump. The return sludge 76 and the sludge 80 can be added to the oil-containing wastewater 2 inside the adjustment tank 32.

  The pressurized levitation tank 34 receives the oil-containing wastewater 50 (which may contain return sludge, PAC, or agglomerated polymer) supplied from the adjustment tank 32, performs a levitation separation process, and discharges the floss 58 and the separated water 60. To do. Further, the floss 58 can be supplied to the dispersion tank 36 or the anaerobic tank 38. Further, the separated water 60 can be supplied to the inlet or outlet of the activated sludge tank 42.

The dispersion tank 36 receives the oil / fat residue 64 and / or the return sludge, and stirs the floss 58 together with these to discharge the dispersion treated water 66.
The dispersion tank 36 has a storage part and a stirring device inside thereof, and is configured so that the inside of the storage part can be stirred by the stirring device. Moreover, the dispersion tank 36 is configured to receive the oil residue 64 and the sludge returned by the sludge return means 62. Specifically, the sludge return means 62 connects the return sludge 76 and the sludge 80 in the aerobic tank 40 and the sedimentation tank 44 to the dispersion tank 36 by piping, and transfers the return sludge 76 and the sludge 80 by the action of the pump. The return sludge 76 and the sludge 80 can be added to the floss 58 inside the dispersion tank 36.
The dispersion tank 36 can receive the oil residue 64 and / or the return sludge, stir the floss 58 together with them, and discharge it as the dispersion treated water 66.

The anaerobic tank 38 has a storage part and is configured so that the storage part can be sealed, and is equipped with a stirrer so that the inside can be stirred. Moreover, it is comprised so that an inside can be divided into 2 parts or 3 parts. The anaerobic tank 38 receives the dispersed treated water 66 and / or the floss 58, performs anaerobic treatment, and discharges the anaerobic treated water 68.
Further, the anaerobic tank 38 is configured to be able to receive the returned sludge by the sludge returning means 70. Specifically, the sludge return means 70 connects the return sludge 76 and the sludge 80 in the aerobic tank 40 and the sedimentation tank 44 to the anaerobic tank 38 by piping, and transfers the return sludge 76 and the sludge 80 by the action of the pump. The return sludge 76 and the sludge 80 can be added to the floss 58 or the dispersed treated water 66 inside the anaerobic tank 38.
In addition, as described above, the anaerobic tank 38 is configured so that when the oil residue 64 is generated, it can be collected and supplied to the dispersion tank 36.

The aerobic tank 40 has a storage part, and is configured to be able to supply air into the storage part. Moreover, it is comprised so that an inside can be divided into 2 parts or 3 parts. The aerobic tank 40 receives anaerobic treated water 68, performs aerobic treatment by the action of aerobic bacteria, facultative anaerobic bacteria, etc., discharges a part of the reaction liquid as return sludge 76, and performs aerobic treatment. Discharge as water 72.
Moreover, the aerobic tank 40 is comprised so that return sludge can be received by the sludge return means 74. FIG. Specifically, the sludge return means 74 connects the return sludge 76 and the sludge 80 in the aerobic tank 40 and the settling tank 44 to the aerobic tank 40 from the discharge port of the return sludge 76 and the sludge 80, and the return sludge 76 and the sludge 80 by the action of the pump. The return sludge 76 and the sludge 80 are transferred and added to the vicinity of the inlet of the aerobic tank 40.
Further, as described above, the aerobic tank 40 is configured such that when the oil residue 64 is generated, it can be collected and supplied to the dispersion tank 36. Further, the aerobic tank 40 is configured so that the reaction liquid in the vicinity of the outlet can be discharged as the return sludge 76.

  The activated sludge tank 42 has a storage part, can supply air into the storage part, and is configured to be able to stir, and the inside is divided into three parts. The activated sludge tank 42 receives the aerobic treated water 72 (which may include the separated water 60), performs a conventionally known activated sludge treatment, and discharges the activated sludge treated water 78.

  The sedimentation tank 44 is configured to receive activated sludge treated water 78 (which may include separated water 60). The sediment is discharged as sludge 80 and the supernatant is discharged as treated water 82.

  Next, the experimental apparatus 90 will be described. The experimental apparatus 90 shown in FIG. 4 is partially different from the experimental apparatus 30 shown in FIG. Specifically, the experimental apparatus 90 does not have the pressurized levitation tank 34 and the activated sludge tank 42, but has two aerobic tanks (a first aerobic tank and a second aerobic tank). Below, the experimental apparatus 90 is demonstrated in detail about a different location from the experimental apparatus 30. FIG. In FIG. 4, the same reference numerals are given to the same components of the experimental apparatus 90 as in the experimental apparatus 30 illustrated in FIG. 3.

The experimental apparatus 90 shown in FIG. 4 has the adjustment tank 32, the dispersion tank 36, the anaerobic tank 38, the 1st aerobic tank 401, the 2nd aerobic tank 402, and the sedimentation tank 44. The experimental apparatus 90 has sludge return means 52, 62, 70, 74. Two aerobic tanks (the first aerobic tank and the second aerobic tank) and the sedimentation tank 44 correspond to the aerobic treatment means of the apparatus of the present invention.
The adjustment tank 32, the dispersion tank 36, the anaerobic tank 38, the sedimentation tank 44, and the sludge return means 52, 62, 70, 74 are the same as those in the experimental apparatus 30 shown in FIG. Since the experimental apparatus 90 shown in FIG. 4 does not have the pressurized levitation tank 34, the oil-containing wastewater 50 discharged from the adjustment tank 32 (which may include return sludge, PAC, or agglomerated polymer) / Or supplied to the anaerobic tank 38. Separated water 60 is not generated.

The 1st aerobic tank 401 and the 2nd aerobic tank 402 are respectively the aspects similar to the aerobic tank 40 which the experimental apparatus 30 has. That is, each has a storage part and is comprised so that air can be supplied in the storage part. Moreover, it is comprised so that an inside can be divided into 2 parts or 3 parts.
The first aerobic tank 401 receives the anaerobic treated water 68, performs an aerobic treatment by the action of aerobic bacteria, facultative anaerobic bacteria, and the like, and discharges the first aerobic treated water 73. The second aerobic tank 402 receives the first aerobic treated water 73, performs an aerobic treatment by the action of aerobic bacteria, and discharges the second aerobic treated water 79.
Further, the first aerobic tank 401 is configured to receive the returned sludge by the sludge returning means 74. Further, as described above, when the oil residue 64 is generated, the oil residue 64 can be collected and supplied to the dispersion tank 36. Furthermore, the 1st aerobic tank 401 is comprised so that the reaction liquid near an outflow port can be transferred and discharged as return sludge. The return sludge 76 is configured to be usable as return sludge by the sludge return means 52, 62, 70, 74, similarly to the aerobic tank 40 of the experimental apparatus 30.

  The settling tank 44 is the same mode as the settling tank 44 which the experimental apparatus 30 shown in FIG. 1 has. The second aerobic treated water 79 is received, the sediment is discharged as sludge 80, and the supernatant is discharged as treated water 82.

Using the experimental apparatus 30 or the experimental apparatus 90, the oil-containing wastewater 50 discharged from the food factory was treated under various conditions.
In addition, only the process of processing the fat and oil containing waste water 50 by the pressurization float tank 34 was made into the batch type, and the other process performed the continuous process.

<Example 1>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG. The amount of treated water in the continuous treatment was 3 L / day.

  In Example 1, the return sludge generated from the aerobic tank 40 is added to the adjustment tank 32 (that is, the return sludge 76 is added as return sludge by the sludge return means 52), and the PAC addition means 54 and the agglomerated polymer are further added. PAC and agglomerated polymer were added by means 56. Here, the return sludge was added in such an amount that the SS concentration of the oil-containing wastewater 50 in the adjustment tank 32 after the return sludge was added was 150 mg-SS / L. Moreover, the addition amount of PAC was 300 mg / L with respect to the oil-containing waste water 50 in the adjustment tank 32. Furthermore, the addition amount of the aggregation polymer was set to 1 mg / L with respect to the oil-containing wastewater 50 in the adjustment tank 32.

Next, the fat and oil-containing wastewater 50 to which the return sludge, PAC, and the agglomerated polymer were added was treated in the pressurized flotation tank 34. The entire amount of the obtained floss 58 was supplied to the dispersion tank 36. In addition, the volume ratio of the floss 58 and the separated water 60 was 1:39. In Example 1, the dispersion treatment using the dispersion tank 36 was not performed.
The entire amount of the separated water 60 was supplied to the inlet of the activated sludge tank 42. That is, the separated water 60 was joined to the aerobic treated water 72 and then treated in the activated sludge tank 42.

In the anaerobic tank 38, the tank was sealed and adjusted by adding NaOH appropriately so that the pH in the tank was 8.5. Moreover, it adjusted so that the temperature in a tank might be 37 degreeC. Furthermore, the inside was mechanically stirred. The residence time in the anaerobic tank 38 was 4 days.
Such processing in the anaerobic tank 38 corresponds to an anaerobic treatment.
In the aerobic tank 40, it adjusted by adding NaOH suitably so that pH in a tank might be set to 8.0. Moreover, it adjusted so that the temperature in a tank might be 37 degreeC. Furthermore, it aerated on the conditions of 1 L / min. The residence time in the aerobic tank 40 was 5 days.

  In the activated sludge tank 42, stirring was performed while venting under the condition that the dissolved oxygen concentration of the tank contents was 3.0 mg / L. The residence time in the activated sludge tank 42 was 6 hours.

In Example 1, the number of partitions in the anaerobic tank 38 and the aerobic tank 40 was adjusted, and the four cases as shown in Table 1 were processed. Specifically, in Example 1-1, the anaerobic tank 38 is not partitioned and the aerobic tank 40 is not partitioned, and in Example 1-2, the anaerobic tank 38 is not partitioned and the aerobic tank 40 is divided into two parts. In Example 1-3, the anaerobic tank 38 was not partitioned, and the aerobic tank 40 was divided into three parts. In Example 1-4, the anaerobic tank 38 was divided into three parts, and the aerobic tank 40 was divided into three parts.
In addition, for comparison, the case where only the aerobic tank 40 is processed without performing the process with the anaerobic tank 38 (Comparative Example 1-1) and the process with only the anaerobic tank 38 without performing the process with the aerobic tank 40 are performed. And the case (Comparative Example 1-2). In Comparative Example 1-1, the aerobic tank 40 was divided into three, and in Comparative Example 1-2, the anaerobic tank 38 was divided into three.

  The fat and oil-containing wastewater 50 is treated using such an experimental apparatus 30, and in each of the total of six cases of the examples and comparative examples, the fat-and-oil containing wastewater 50, the floss 58, the separated water 60, the anaerobic treated water 68, The hexane extract concentration was measured for the gas treated water 72 and the treated water 82. In addition, the measuring method of a hexane extract density | concentration is as above-mentioned. The results are shown in Table 1.

As shown in Table 1, the hexane extract concentration of the treated water 82 satisfied the sewage discharge standard value of 30 mg / L in all Examples. Moreover, in all the Examples, generation | occurrence | production of the fats and oils residue was not recognized in the anaerobic tank 38 and the aerobic tank 40. FIG.
On the other hand, in the two comparative examples, the hexane extract concentration of the treated water 82 was high, and the sewage discharge standard value was not satisfied. In Comparative Example 1-1, an oil residue was generated.

  From the results of Example 1, it is considered that the froth can be efficiently treated without generating oil residue by the biological treatment combining the anaerobic treatment and the aerobic treatment. Moreover, it is thought that water quality can be improved by providing a partition in an anaerobic tank and / or an aerobic tank. Floss anaerobic treatment does not involve vigorous aeration treatment, so it is estimated that it is possible to prevent the formation of oil residue, and emulsification by biosurfactant produced by anaerobic microorganisms and microorganisms that can grow in microaerobic environments It is estimated that the treatment speed in the subsequent aerobic treatment can be improved by solubilization of the fat and oil by the action and the action of both microorganisms to lower the molecular weight of the fat and oil contained in the froth. The In the semi-anaerobic treatment of floss as in Example 1, anaerobic digestion with main methane fermentation as the main reaction is not performed, and although the reduction in fats and oils hardly progresses, the combination with the aerobic treatment in the latter stage It is thought that decomposition of fats and oils can be achieved.

<Example 2>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 2, in order to promote the reaction efficiency in the biological treatment process of froth, the necessity of return sludge, the supply source of return sludge, and the influence of the supply destination were investigated.
The experiment was the same as in Example 1-4 except that the dispersion treatment was performed in the dispersion tank 36 and the conditions of the supply source and the supply destination of the returned sludge.
Here, the distributed processing conditions will be described. In the dispersion tank 36, NaOH was appropriately added to the received floss 58 to maintain the pH in the tank at 8.5 to 9.5. Moreover, the temperature in the tank was kept at 50 ° C. Furthermore, the inside was mechanically stirred. The residence time in the dispersion tank 36 was 1 hour.
And the fat-and-oil containing waste water 50 was processed using the returned sludge as follows.

In Example 2-1, the return sludge 76 discharged from the aerobic tank 40 was supplied to the adjustment tank 32 by the sludge return means 52.
In Example 2-2, the sludge 80 discharged from the sedimentation tank 44 was supplied to the adjustment tank 32 by the sludge return means 52.
In Example 2-3, the return sludge 76 discharged from the aerobic tank 40 was supplied to the dispersion tank 36 by the sludge return means 62.
In Example 2-4, the sludge 80 discharged from the settling tank 44 was supplied to the dispersion tank 36 by the sludge return means 62.
In Example 2-5, the return sludge 76 discharged from the aerobic tank 40 was supplied to the vicinity of the inlet of the anaerobic tank 38 by the sludge return means 70.
In Example 2-6, the sludge 80 discharged from the settling tank 44 was supplied to the vicinity of the inlet of the anaerobic tank 38 by the sludge return means 70.
In Comparative Example 2-1, the return sludge 76 discharged from the aerobic tank 40 was supplied to the vicinity of the inlet of the aerobic tank 40 by the sludge return means 74.
In Comparative Example 2-2, the sludge 80 discharged from the settling tank 44 was supplied to the vicinity of the inlet of the aerobic tank 40 by the sludge return means 74.
In Comparative Example 2-3, neither the return sludge 76 nor the sludge 80 was used.

The fat-and-oil containing waste water 50 is processed using such an experimental apparatus 30, and in each of the total of nine cases of the examples and comparative examples, the fat-and-oil containing waste water 50, the floss 58, the separated water 60, the aerobic treated water 72, and The hexane extract concentration was measured for the treated water 82. In addition, the amount of oil residue was measured.
In addition, the measuring method of the generation amount of fat and oil residue collect | recovered the generated fat and oil residue, and measured mass. The results are shown in Table 2.

As shown in Table 2, although no fat residue was observed in Example 2-1 and Example 2-2, fat residue was generated in other Examples and Comparative Examples.
From these results, it is considered preferable to use sludge return for improving the reaction efficiency in the biological treatment of froth and preventing the generation of oil residue. In addition, the sludge in the aerobic tank 40 and the sedimentation tank 44 is effective as a supply source of the return sludge. In particular, the sludge in the former aerobic tank 40 is more effective for promoting the oil treatment and preventing the generation of oil residue. It is thought that. In the aerobic tank 40, a high effect is obtained by the presence of a high concentration of microbial species having a particularly high ability to decompose oil, and the secretion of biosurfactants (microbe surfactants) for dispersing the oil. it is conceivable that.

  In addition, the adjustment tank 32 is most effective as the supply destination of the return sludge, and then the effect is recognized in the dispersion tank 36 and the anaerobic tank 38. On the other hand, the return sludge supply effect by the sludge return means 74 to the aerobic tank 40 was not high. Such an effect is presumed to be that the dispersibility of the oil contained in the floss can be optimized by setting the supply destination of the return sludge to the front stage of the pressurized flotation tank 34. Moreover, the volume of the object of an anaerobic process and an aerobic process is made small by making the water | moisture content contained in a returned sludge into the separation water 60 by making the supply destination of a return sludge into the front stage from the pressurized levitation tank 34, and an anaerobic tank It is estimated that the residence time in the aerobic tank can be increased.

<Example 3>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 3, the effect of the dispersion tank 36 installed as a pretreatment process in which the floss 58 was subjected to anaerobic treatment was examined.
Example 3-1 is based on the conditions of Example 2-3. Floss 58 is supplied to dispersion tank 36, and return sludge 76 discharged from aerobic tank 40 is supplied to dispersion tank 36 and discharged. Dispersed treated water 66 was supplied to the anaerobic tank 38. Further, the oil residue 64 generated in the anaerobic tank 38 and the aerobic tank 40 was collected and supplied to the dispersion tank 36.
Example 3-2 is the same as the condition of Example 2-3, and the floss 58 is supplied to the dispersion tank 36, and the return sludge 76 discharged from the aerobic tank 40 is supplied to the dispersion tank 36 and discharged. Dispersed treated water 66 was supplied to the anaerobic tank 38. Moreover, the fat residue 64 generated in the anaerobic tank 38 and the aerobic tank 40 was not supplied to the dispersion tank 36.
In Comparative Example 3-1, the return sludge 76 discharged from the aerobic tank 40 was supplied to the vicinity of the inlet of the aerobic tank 40 based on the conditions of Comparative Example 2-1. The floss 58 was not supplied to the dispersion tank 36, but the entire amount was supplied to the anaerobic tank 38. Further, the oil residue 64 generated in the anaerobic tank 38 and the aerobic tank 40 was collected and supplied to the dispersion tank 36.
In Comparative Example 3-2, the return sludge 76 discharged from the aerobic tank 40 was supplied to the vicinity of the inlet of the aerobic tank 40 based on the conditions of Comparative Example 2-1. The floss 58 was not supplied to the dispersion tank 36, but the entire amount was supplied to the anaerobic tank 38. Moreover, the fat residue 64 generated in the anaerobic tank 38 and the aerobic tank 40 was not supplied to the dispersion tank 36.

  The fat-and-oil containing waste water 50 was processed using such an experimental apparatus 30, and the generation amount of the total fat residue in the anaerobic tank 38 and the aerobic tank 40 was measured in each of a total of four cases of an Example and a comparative example. The results are shown in Table 3.

As shown in Table 3, in Example 3-1 and Example 3-2, the generation of oil and fat residues was negligible.
Moreover, it is thought that generation | occurrence | production of fat and oil residue can be suppressed notably by processing the floss 58 in the dispersion tank 36. FIG.
Moreover, it is thought that the generation | occurrence | production amount of fat and oil residue can be suppressed by collect | recovering the fat and oil residue which generate | occur | produced in the anaerobic tank 38 and the aerobic tank 40, and performing a process with the dispersion | distribution tank 36.

<Example 4>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 4, an experiment was conducted on the influence of the amount of return sludge supplied to the adjustment tank 32. The experiment was performed based on the conditions of Example 2-1.
In Example 4-1, the return sludge concentration of the oil-containing wastewater 50 after adding the return sludge in the adjustment tank 32 was set to 20 mg-SS / L.
In Example 4-2, the return sludge concentration of the oil-containing wastewater 50 after adding the return sludge in the adjustment tank 32 was set to 50 mg-SS / L.
In Example 4-3, the return sludge concentration of the oil-containing wastewater 50 after the return sludge was added in the adjustment tank 32 was set to 100 mg-SS / L.
In Example 4-4, the return sludge concentration of the oil-containing wastewater 50 after the return sludge was added in the adjustment tank 32 was set to 300 mg-SS / L.
In Example 4-5, the return sludge concentration of the oil-containing wastewater 50 after adding the return sludge in the adjustment tank 32 was set to 1000 mg-SS / L.
In Example 4-6, the return sludge concentration of the oil-containing wastewater 50 after the return sludge was added in the adjustment tank 32 was set to 2000 mg-SS / L.

  And in each of a total of six cases of Example 4, the hexane extract density | concentration was measured about the fat and oil containing waste water 50, the floss 58, the separation water 66, the aerobic treated water 72, and the treated water 82. The results are shown in Table 4.

  From Table 4, the optimum value of the supply amount of sludge returned to the adjustment tank 32 is such that the return sludge concentration in the oil-containing wastewater 50 after adding the return sludge in the adjustment tank 32 is 50 to 1000 mg-SS / L. It is considered to be a quantity.

<Example 5>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 5, the influence of pH in the anaerobic treatment of floss was examined. The experiment was based on the conditions of Example 1-4, and the pH in the anaerobic tank 38 was adjusted.
In Example 5-1, the tank pH in the anaerobic tank 38 was adjusted to 7.2.
In Example 5-2, the pH in the anaerobic tank 38 was adjusted to 7.8.
In Example 5-3, the pH in the anaerobic tank 38 was adjusted to 8.3.
In Example 5-4, the pH in the anaerobic tank 38 was adjusted to 8.8.
In Example 5-5, the pH in the anaerobic tank 38 was adjusted to 9.5.

  And in each of a total of five cases of Example 5, the hexane extract density | concentration and the generation amount of fat residue were measured about the fat-and-oil containing waste water 50, the floss 58, the separation water 60, the aerobic treated water 72, and the treated water 82. . The results are shown in Table 5.

  From Table 5, it is considered that the pH in the anaerobic tank 38 is preferably 7.2 to 8.8.

<Example 6>
The fat and oil containing waste water 50 was processed using the experimental apparatus 90 shown in FIG.
In Example 6, the influence of the temperature in the anaerobic tank 38 was examined. The amount of treated water in the continuous treatment was 3 L / day.

  In Example 6, the return sludge 76 generated from the first aerobic tank 401 was added to the adjustment tank 32. That is, the returned sludge 76 was added to the fat-and-water containing waste water 50 as returned sludge by the sludge returning means 52. Here, the return sludge was added in such an amount that the return sludge concentration of the oil-containing wastewater 50 in the adjustment tank 32 after the return sludge was added was 500 mg-SS / L.

Next, the entire amount of the oil-containing wastewater 50 to which the return sludge was added was supplied to the dispersion tank 36. PAC and agglomerated polymer were not added.
In the dispersion tank 36, NaOH was appropriately added to the received oil-and-fat drainage 50 to maintain the pH in the tank at 8.5 to 9.5, and the tank temperature was maintained at 50 ° C. Furthermore, the inside was mechanically stirred. The residence time in the dispersion tank 36 was 1 hour.

  In the anaerobic tank 38, the tank was sealed and adjusted by adding NaOH appropriately so that the pH in the tank was 8.5. Moreover, it adjusted so that the temperature in a tank might be 37 degreeC. Furthermore, the inside was mechanically stirred. The residence time in the anaerobic tank 38 was 20 hours.

  In the 1st aerobic tank 401, it adjusted by adding NaOH suitably so that pH in a tank might be set to 8.0. Moreover, it adjusted so that the temperature in a tank might be 37 degreeC. Furthermore, it aerated and stirred on the conditions of 1 L / min. The residence time in the first aerobic tank 401 was 6 hours.

  In the 2nd aerobic tank 402, it adjusted by adding NaOH suitably so that pH in a tank might be set to 8.0. Moreover, it adjusted so that the temperature in a tank might be 37 degreeC. Furthermore, it aerated and stirred on the conditions of 1 L / min. Moreover, the residence time in the 2nd aerobic tank 402 was 6 hours.

And the experiment which changed the tank internal temperature in the anaerobic tank 38 was conducted.
In Example 6-1, the tank temperature in the anaerobic tank 38 was maintained at 20 ° C.
In Example 6-2, the temperature inside the anaerobic tank 38 was maintained at 30 ° C.
In Example 6-3, the temperature inside the anaerobic tank 38 was maintained at 37 ° C.
In Example 6-4, the temperature inside the anaerobic tank 38 was maintained at 47 ° C.
In Example 6-5, the temperature inside the anaerobic tank 38 was maintained at 58 ° C.

  And in each of a total of five cases of Example 6, the hexane extract density | concentration was measured about the fat-and-oils containing waste water 50, the anaerobic treated water 68, the 1st aerobic treated water 73, and the 2nd aerobic treated water 79. The results are shown in Table 6.

From Table 6, it is considered that the temperature inside the anaerobic tank 38 is preferably 20 to 58 ° C.
Moreover, in Example 6, generation | occurrence | production of the fats and oils residue was not recognized on all the conditions.

<Example 7>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 7, in order to promote the reaction efficiency in the anaerobic treatment and aerobic treatment of froth, the effects of sulfuric acid addition and aeration (oxygen input) in the anaerobic treatment were examined. The experiment was based on the conditions of Example 1-4, and the reaction conditions in the anaerobic tank 38 were adjusted. Moreover, the oxidation-reduction potential in the liquid in the tank of the anaerobic tank 38 was measured using the ORP meter by a platinum electrode.

In Example 7-1, the anaerobic tank 38 was sealed and ventilation was not performed. Moreover, sulfuric acid was not added.
In Example 7-2, the anaerobic tank 38 was sealed and ventilation was not performed, and sulfuric acid was added to adjust the sulfate ion concentration in the tank to 30 mg / L.
In Example 7-3, the anaerobic tank 38 was sealed and ventilation was not performed, and sulfuric acid was added to adjust the sulfuric acid ion concentration in the tank to 1,000 mg / L.
In Example 7-4, the anaerobic tank 38 was sealed and ventilation was not performed, and sulfuric acid was added to adjust the sulfuric acid ion concentration in the tank to 3,000 mg / L.
In Example 7-5, air was blown onto the surface of the liquid in the tank so that the oxidation-reduction potential in the liquid in the tank of the anaerobic tank 38 was −250 mV. Moreover, sulfuric acid was not added.
In Example 7-6, air was blown onto the surface of the liquid in the tank so that the oxidation-reduction potential in the liquid in the tank of the anaerobic tank 38 was -180 mV. Further, sulfuric acid was added to adjust the sulfate ion concentration in the tank to 30 mg / L.
In Example 7-7, air was blown onto the surface of the liquid in the tank so that the oxidation-reduction potential in the liquid in the tank of the anaerobic tank 38 was −50 mV. Moreover, sulfuric acid was not added.

  And in each of a total of seven cases of an Example, hexane extract density | concentration and fat residue of fat and oil containing waste water 50, floss 58, separated water 60, anaerobic treated water 68, aerobic treated water 72, and treated water 82 The amount generated was measured. The results are shown in Table 7.

  From Table 7, it is considered that the treatment performance is improved by the addition of sulfuric acid and aeration (oxygen input) in the anaerobic treatment.

<Example 8>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 8, the influence of pH in the aerobic treatment of the anaerobic treated water 68 was examined. The experiment was based on the conditions of Example 1-3, and the pH in the aerobic tank 40 was adjusted.
In Example 8-1, the tank pH in the aerobic tank 40 was adjusted to 7.2.
In Example 8-2, the pH in the tank in the aerobic tank 40 was adjusted to 7.5.
In Example 8-3, the pH in the aerobic tank 40 was adjusted to 8.5.
In Example 8-4, the pH in the aerobic tank 40 was adjusted to 9.0.
In Example 8-5, the pH in the aerobic tank 40 was adjusted to 10.0.
In Example 8-6, the pH in the aerobic tank 40 was adjusted to 11.0.

  And in each of a total of six cases of an Example, the hexane extract density | concentration and the generation amount of fats and oil residue were measured about the fat-and-oil containing waste water 50, the floss 58, the separation water 60, the aerobic treated water 72, and the treated water 82. The results are shown in Table 8.

  From Table 8, it is considered that the pH in the aerobic tank 40 is preferably 7.5 to 11.0.

<Example 9>
The fat and oil containing waste water 50 was processed using the experimental apparatus 90 shown in FIG.
In Example 9, the influence of the temperature in the aerobic tank was examined. The experiment is based on the conditions of Example 1-3 except that solid-liquid separation is not performed in the pressurized levitation tank 34, and the temperature in the first aerobic tank 401 and the second aerobic tank 402 is adjusted. did.
In Example 9-1, the internal temperature was maintained at 20 ° C.
In Example 9-2, the temperature in the tank was maintained at 30 ° C.
In Example 9-3, the temperature in the tank was maintained at 37 ° C.
In Example 9-4, the temperature in the tank was maintained at 47 ° C.
In Example 9-5, the temperature in the tank was maintained at 58 ° C.

  And in each of a total of five cases of an Example, the hexane extract density | concentration was measured about the fat-and-oils containing waste water 50, the anaerobic treated water 68, the 1st aerobic treated water 73, and the 2nd aerobic treated water 79. The results are shown in Table 9.

From Table 9, it is considered that the temperature in the first aerobic tank 401 and the second aerobic tank 402 is preferably 30 to 58 ° C.
Moreover, in Example 9, generation | occurrence | production of the fats and oils residue was not recognized on all the conditions.

<Example 10>
The fat and oil containing waste water 50 was processed using the experimental apparatus 30 shown in FIG.
In Example 10, the influence of the partition installation location in the aerobic tank 40, the effect when a structure (a microbial membrane unit for forming a microbial film) is installed on the water surface of the aerobic tank 40, and the aerobic tank 40 are used. The influence when the foam generated in the above was discharged to the anaerobic tank 38 in the previous stage was examined.
Here, the microorganism membrane unit is a unit in which a plurality of polyethylene nonwoven fabrics are suspended in the vertical direction.
In the experiment, Example 1-2 was used as a basic condition.

In Example 10-1, the partition was installed in the position in which the volume ratio of the front | former stage and back | latter stage in the aerobic tank 40 will be 1: 2. The microbial membrane unit was not installed, and the foam generated in the aerobic tank 40 was not returned to the anaerobic tank 38.
In Example 10-2, the partition was installed in the position in which the volume ratio of the front | former stage and back | latter stage in the aerobic tank 40 becomes 1: 1. The microbial membrane unit was not installed, and the foam generated in the aerobic tank 40 was not returned to the anaerobic tank 38.
In Example 10-3, the partition was installed in the position in which the volume ratio of the front | former stage and back | latter stage in the aerobic tank 40 will be 2: 1. The microbial membrane unit was not installed, and the foam generated in the aerobic tank 40 was not returned to the anaerobic tank 38.
In Example 10-4, the partition was installed in the position in which the volume ratio of the front | former stage and back | latter stage in the aerobic tank 40 is set to 1: 1. And the microbial membrane unit was installed in the upper part of the liquid level in an aerobic tank. The foam generated in the aerobic tank 40 was not returned to the anaerobic tank 38.
In Example 10-5, the partition was installed in the position in which the volume ratio of the front | former stage and back | latter stage in the aerobic tank 40 is set to 1: 1. No microbial membrane unit was installed. However, the foam generated in the aerobic tank 40 was returned to the anaerobic tank 38.

And in each of a total of five cases of an Example, hexane extract about the sample water in each of the front stage part and rear stage part in the aerobic tank 40 in the fat and oil containing waste water 50, the floss 58, the separation water 66, and the treated water 82, and the aerobic tank 40 Concentration was measured. Moreover, MLSS was measured about the sample water in each of the front | former stage part and back | latter stage part in the aerobic tank 40. FIG. Furthermore, the dissolved oxygen amount (DO) was measured for the sample water in the front stage in the aerobic tank 40.
In addition, the measuring method of the amount of dissolved oxygen was performed by the oxygen electrode method using the dissolved oxygen electrode.
The MLSS measurement method is based on the factory drainage test method (JIS K0102 14).
The results are shown in Table 10.

From Table 10, it is considered that the partition 82 installed in the aerobic tank 40 can obtain treated water 82 with better water quality if it is installed at a position that equally divides the tank. Moreover, the MLSS concentration in the aerobic tank 40 can be kept high and the processing performance can be improved under the condition that the dissolved oxygen concentration in the previous stage in the aerobic tank 40 is 0.6 mg / L or less.
When the microbial membrane unit was installed in the aerobic tank 40, the result with the highest oil removal performance was obtained.
By introducing the foam generated in the aerobic tank 40 into the anaerobic tank 38, it was not necessary to add an antifoaming agent, and there was no generation of oil residue, and it was possible to obtain treated water with good water quality.

DESCRIPTION OF SYMBOLS 1 Apparatus of this invention 2,50 Oil-containing wastewater 3 Anaerobic treatment means 4,68 Anaerobic treatment water 5Aerobic treatment means 7,82 Treated water 9,11,23,26,52,62,70,74 Sludge return Means 10 Apparatus 12, 54 PAC addition means 13, 56 Aggregated polymer addition means 18 Concentration means 19 Dispersion means 21 Concentrate 22, 60 Separated water 24, 64 Oil residue 25, 66 Dispersed treated water 8, 80 Sludge 28, 76 Return sludge 30, 90 Experimental device 36 Dispersion tank 38 Anaerobic tank 40 Aerobic tank 401 First aerobic tank 402 Second aerobic tank 42 Activated sludge tank 44 Precipitation tank 58 Floss 72 Aerobic treated water 73 First aerobic treated water 78 Activity Sludge treated water 79 Second aerobic treated water

Claims (10)

Anaerobic treatment step of subjecting the fat-containing wastewater to anaerobic treatment and discharging anaerobic treated water;
An aerobic treatment step of applying an aerobic treatment to the anaerobic treated water;
In the method for treating fat-containing wastewater, comprising the sludge generated in the aerobic treatment step, the sludge returning step of supplying the sludge to the fat-containing wastewater,
The anaerobic treatment step, an oxidation-reduction potential while spraying an appropriate amount of air was adjusted to be less -50 mV, chosen from anaerobic bacteria and facultative anaerobes or Ranaru group relative to the oil-containing wastewater The processing method of the fat-and-oil wastewater characterized by making at least 1 act on the fat-and-oil content contained in fat-and-oil containing wastewater. The oil-and-fat-containing wastewater is floated and separated in a pressurized flotation tank to obtain a concentrate (floss) and separated water, and includes a pressurized flotation step for supplying the concentrate to the anaerobic treatment step,
The method for treating oil-containing wastewater according to claim 1, wherein the sludge is supplied to the oil-containing wastewater by the sludge returning step. The anaerobic treatment step includes
Claims wherein the oil-containing wastewater at least one limit of the time to act selected from anaerobic bacteria and facultative anaerobes or Ranaru group and 20 hours, the upper limit of this time characterized by a 15 days Item 3. A method for treating oil-containing wastewater according to item 1 or 2. The anaerobic treatment step includes
It adjusts so that the oxidation-reduction potential of the said fat-containing wastewater may be -50--250 mV, The processing method of the fat-containing wastewater in any one of Claims 1-3 characterized by the above-mentioned.   In the aerobic treatment step, the foam removal by any one of the defoaming agent addition means for removing the foam generated from the surface of the treatment liquid during the treatment and the foam adhesion means (structure) for attaching the foam. The processing method of the fat and oil containing waste water in any one of Claims 1-4 provided with the means. An adding means for adding sludge and agglomerated polymer to the oil-containing wastewater;
A concentration and separation means for separating the oil and fat-containing wastewater to which the sludge and the agglomerated polymer are added into a concentrate and separated water;
The redox potential while spraying an appropriate amount of air to the concentrate was adjusted to be less -50 mV, at least one selected from the anaerobic bacteria and facultative anaerobes or Ranaru group to the concentrate An anaerobic tank for obtaining anaerobic treated water from the concentrate by acting;
Aerobic treatment of the anaerobic treated water to obtain aerobic treated water and sludge;
Sludge returning means for supplying the sludge from the aerobic tank back to the oil-containing wastewater and the concentrate;
The processing apparatus of the fat-and-oil containing waste water characterized by having.   The anaerobic tank residence time has a lower limit of 20 hours and an upper limit of 15 days, the pH of the anaerobic tank is 7.2 or more and 11.0 or less, the temperature of the anaerobic tank is 20 ° C. or more and 58 ° C. or less, and the oxidation The apparatus for treating oil-containing wastewater according to claim 6, wherein the reduction potential is -50 to -250 mV. A concentration and separation tank for concentrating the fat and oil contained in the fat and oil-containing wastewater to obtain a concentrate and separated water;
Adjusting the redox potential to be −50 mV or less while blowing an appropriate amount of air to the concentrate, causing anaerobic bacteria to act on the concentrate, anaerobically treating the concentrate, and anaerobic treatment An anaerobic tank to get water,
Aerobic treatment of the anaerobic treated water to obtain aerobic treated water and sludge;
An activated sludge tank for obtaining activated sludge treated water by treating the separated water and the aerobic treated water with activated sludge;
A settling tank for precipitating the activated sludge treated water to obtain sludge and treated water;
Sludge return means for supplying the sludge from at least one of the aerobic tank and the settling tank to the oil-containing wastewater;
The processing apparatus of the fat-and-oil containing waste water characterized by having.   The oil-containing wastewater is received and stored, and sludge from at least one of the aerobic tank and the sedimentation tank, a flocculated polymer, and at least one of PAC are supplied, and the oil-containing wastewater in which these are stored is stored. The apparatus for treating oil-containing wastewater according to claim 8, further comprising an adjustment tank to be supplied to the concentration separation tank. Concentrate from the concentration / separation tank or fat / oil-containing wastewater from the adjustment tank and return sludge from the aerobic tank are supplied and stirred to obtain dispersed treated water. A dispersion tank to be supplied to the anaerobic tank,
The processing apparatus of the fat-and-oil containing waste water of Claim 9 characterized by the above-mentioned.

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