JP2015208693A - Method and apparatus for wastewater treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for treatment of oil and fat-containing wastewater which suppresses occurrence of oil and fat residue.SOLUTION: A treatment method of oil and fat-containing wastewater includes an aerobic treatment step of conducting an aerobic treatment by supplying micro-bubbles to oil and fat-containing wastewater.

Description

  The present invention relates to a wastewater treatment method and a wastewater treatment apparatus.

  There is a need for a treatment method for efficiently separating fats and oils from wastewater containing a large amount of fats and oils such as food factory wastewater and domestic wastewater. Then, the processing method and processing apparatus which isolate | separate fats and oils using a microbubble are proposed as a conventional method.

  In Patent Document 1, waste containing oil is charged, a treatment tank filled with a non-acidic solution, a separation tank capable of separating oil from a mixed liquid of the solution and oil flowing in from the treatment tank, There is described an oil separation device comprising a microbubble generating device that generates microbubbles in a solution filling the treatment tank.

  Patent Document 2 includes a pretreatment tank for removing oil and solids in oil-associated water as water to be treated, and the oil-associated water from which oil and solids have been removed in contact with an oxygen source, A water treatment apparatus, characterized by comprising a reaction tank for oxidative decomposition of dissolved organic compounds in the associated water, and further, microbubbles in the oil-associated water in the pretreatment tank. It is described that the product is supplied in a fertile manner.

  In Patent Document 3, the microbubbles (20a) are sent to waste liquid containing foreign matters mainly including oil, including emulsions, and the microbubbles (20a) are raised to the water surface (WL) until the microbubbles (20a) rise to the water surface (WL). The surface of the microbubble (20a) is made to adhere to a foreign substance centered on oil contained in the waste liquid to form floating oil, and the floating oil on the water surface (WL) is forcibly convected so that the floating oil recovery port (40) describes a method for recovering floating oil from waste liquid.

  Patent Document 4 discloses a method for treating accompanying water that is taken out along with production of crude oil or natural gas and contains at least an oil as a processing target substance, and emulsifies by introducing micro-nano bubbles made of ozone-containing gas into the accompanying water. An associated water treatment method is described, which comprises a flocculation step for flocculating oil and a levitation separation step for floating and separating the flocculated emulsified oil as scum to obtain purified water.

  Patent Document 5 discloses an oil / water separation device for separating oil from oil-containing wastewater, and a cylindrical oil / water separation tank standing on the ground and a cylindrical shaft of the oil / water separation tank with an opening facing upward. An oil collecting cup installed in such a manner, an oil discharge pipe for discharging the oil collected in the oil collecting cup to the outside of the oil-water separation tank, and an oil discharge pump installed in the oil discharge pipe , An intermediate treated water discharge pipe for discharging the intermediate treated water from which the oil component has been separated from the oil-containing waste water to the outside of the oil / water separation tank, a bubble supply pipe connected to a lower portion of the oil / water separation tank, and the bubble supply pipe A microbubble generating means for supplying microbubbles having a diameter of 20 to 50 μm to the inside of the oil / water separation tank through an outlet, and a diameter 0 to the inside of the oil / water separation tank via an ejector nozzle connected above the bubble supply pipe. .5-5mm And an oil-containing wastewater supply pipe that supplies the oil-containing wastewater, an oil-containing wastewater supply pump installed in the oil-containing wastewater supply pipe, and a gas self-priming pipe that supplies gas to the ejector nozzle. An oil-water separation apparatus is described in which the oil-containing wastewater supply pipe is connected so that the tip thereof is tangent to the peripheral wall of the oil-water separation tank.

JP 2011-131153 A JP 2013-184124 A JP 2007-38195 A JP 2013-180213 A JP 2013-94704 A

  However, in the conventional methods represented by the above Patent Documents 1 to 5, since a large amount of oily residue is generated after treating wastewater or the like, it is necessary to separately decompose it.

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 fat and oil containing waste_water | drain which does not produce fat residue easily.

The present invention has been intensively studied to solve the above-described problems, and the present invention has been completed.
The present invention includes the following (1) to (6).
(1) A method for treating fat and oil-containing wastewater comprising an aerobic treatment step in which microbubbles are supplied to the fat and oil-containing wastewater to perform aerobic treatment.
(2) In addition, an anaerobic treatment step is provided for performing anaerobic treatment on the fat-containing wastewater to discharge anaerobic treated water,
The method for treating oil-containing wastewater according to (1) above, wherein the aerobic treatment step is a step of supplying the microbubbles to the anaerobic treated water to perform an aerobic treatment.
(3) The aerobic treatment step includes a mixing step of mixing the fat-containing wastewater or the anaerobic treated water and the microbubbles. The method for treating fat-containing wastewater according to (1) or (2) above. .
(4) An apparatus for treating oil-containing wastewater having aerobic treatment means for supplying microbubbles to the oil-containing wastewater to perform aerobic treatment.
(5) Furthermore, it has an anaerobic treatment means for giving anaerobic treatment to the oil-containing wastewater to discharge anaerobic treated water,
The oil and fat-containing wastewater treatment apparatus according to (4), wherein the aerobic treatment means is means for supplying the microbubbles to the anaerobic treatment water to perform an aerobic treatment.
(6) The apparatus for treating oil-containing wastewater according to (4) or (5), wherein the aerobic treatment means includes mixing means for mixing the oil-containing wastewater or the anaerobic treated water and the microbubbles. .

  ADVANTAGE OF THE INVENTION According to this invention, the processing method and processing apparatus of fats and oils containing waste water which cannot produce fat residue easily can be provided.

It is an example of the apparatus of this invention. It is another example of the apparatus of this invention. It is a conceptual diagram for demonstrating the suitable aspect of the apparatus of this invention.

The present invention will be described. This invention is a processing method of the fat-and-oil containing wastewater provided with the aerobic processing process which supplies a microbubble to fat-and-oil containing wastewater and performs an aerobic process. Hereinafter, such a processing method is also referred to as a “method of the present invention”.
Moreover, this invention is a processing apparatus of the fat and oil containing waste_water | drain which has an aerobic processing means which supplies a micro bubble to fat and oil containing waste water and performs aerobic processing. 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.

  Furthermore, in the present invention, the final product obtained by treating the oil-containing wastewater is also referred to as treated water below.

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. Examples of oils and fats include animal and vegetable oils and fats (triglycerides and partially decomposed products thereof). 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, 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 the present invention, aerobic treatment can be performed on oil-containing wastewater that has been pretreated. Therefore, what pre-processed to fat and oil containing wastewater shall correspond to fat and oil containing wastewater in this invention. As one aspect of the oil-containing wastewater in the present invention, for example, in addition to the oil-containing wastewater pretreated, the concentrate obtained by subjecting the oil-containing wastewater to concentration treatment, as described later, dispersed in the oil-containing wastewater Examples thereof include dispersed water obtained by the treatment.

The aerobic process in the present invention will be described.
In the present invention, the aerobic treatment means a treatment in which microorganisms mainly composed of aerobic bacteria living in an aerobic environment are decomposed by acting on oil-containing wastewater.
An aerobic environment is an environment in which oxygen is present, and refers to a state where the dissolved oxygen concentration (DO) is 0 mg / L or more.

In the aerobic treatment in the present invention, microbubbles are supplied to the fat and oil-containing waste water in order to obtain the aerobic environment as described above. That is, microbubbles are supplied as an oxygen source for performing an aerobic treatment.
In the present invention, the microbubble includes fine bubbles having a bubble diameter of 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, more preferably 10 μm or less, and further preferably 5 μm or less. In addition, bubbles having a bubble diameter of less than 1 μm, that is, nanobubbles are also included in the microbubbles of the present invention.
Further, the microbubble is a bubble containing oxygen and may be a bubble of air or oxygen-enriched air.

  The present inventor has found that when microbubbles are supplied to the oil-and-fat-containing wastewater and subjected to aerobic treatment, the oil-and-fat residue is hardly generated. As a reason for this, the present inventor presumes that oxygen can be supplied to the fat-containing wastewater without excessive mixing and stirring, and as a result, coalescence of the dispersed fat can be prevented. Yes. In addition, since microbubbles have a small bubble diameter, the mass transfer coefficient increases and the oxygen dissolution rate also increases. Furthermore, it is estimated that microbubbles can suppress the rising of fats and oils because of their slow rising speed. Moreover, when the bubble diameter of a microbubble is 20 micrometers or less, it is estimated that a microbubble shrink | contracts, dissolution rate becomes larger, and the floating of fats and oils can also be suppressed more.

  In the present invention, the bubble diameters of all the microbubbles may not be within the above range, and a part of the microbubbles only needs to be included in this range. Specifically, among the microbubbles immediately after the occurrence, the frequency in the bubble diameter distribution of 50 μm or less (preferably 30 μm or less, more preferably 20 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less). ) Is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. Here, the micro bubble immediately after generation means the bubble diameter of the micro bubble immediately after being supplied to the aerobic processing means. For example, when an aerobic treatment tank is used as the aerobic treatment means, microbubbles immediately after being released into the fat-containing wastewater in the aerobic treatment tank and microbubbles immediately after being generated in the fat-containing wastewater can be mentioned.

  The measurement method of the bubble diameter and bubble diameter distribution (frequency) of microbubbles is measured using a conventionally known laser diffraction / scattering method. This method is a method of measuring a diffraction / scattered light pattern (scattered light pattern) in association with a bubble diameter when laser light is irradiated to a liquid containing microbubbles. For more details, see Mitsuru Maruyama, “Laser diffraction / scattering method”, the latest technology of microbubbles and nanobubbles, CMC Publishing (2007), p. 31-41.

  The generation method of microbubbles is not particularly limited, and a conventionally known method can be used. For example, a swirling flow type, a static mixer type, an ejector type, a venturi type, a pressure dissolution type, a pore type, a rotary type, an ultrasonic type, a vapor condensation type, an electrolysis type and the like can be mentioned.

  In the present invention, conventionally known aerobic biological treatment can be applied as long as microbubbles are supplied as the aerobic treatment. Specifically, the process which receives fat-and-oils containing waste_water | drain in a tank, and aerated with a microbubble, stirring is illustrated. More specifically, microbubbles are used for conventionally known floating biological treatment methods (batch activated sludge method, continuous activated sludge method, etc.) and biofilm treatment methods (aerobic filter bed method, fluidized bed method, etc.). A method is illustrated.

  The aerobic treatment preferably includes a plurality of types of treatment. For example, it is preferable to apply a fluidized bed method after applying a continuous activated sludge method to fat and oil-containing wastewater. Moreover, it is preferable that it is the process which applies a continuous activated sludge method after performing an aeration process to fat and oil containing waste water. Further, a denitrification step may be incorporated into the above 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 finally obtained is further increased, and treated water having a hexane extract concentration that satisfies the sewage discharge standard value defined in the Sewerage Law can be obtained.

In the present invention, when the aerobic process includes a plurality of types of aerobic processes, at least one of them may be an aerobic process using microbubbles.
For example, when a continuous activated sludge method is applied after aeration treatment is performed on fat and oil-containing wastewater, microbubbles may be used for the aeration treatment and the continuous activated sludge method, or the microbubble may be used in either of these two methods. Bubbles may be used.

  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 oil-and-fat-containing wastewater.

In the aerobic treatment, the lower limit of the time for aerobic bacteria and the like to act on the oil-containing wastewater 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 aerobic bacteria to act on the oil-containing wastewater is within such a range, treated water 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 oil-containing wastewater as described above.

  The aerobic treatment is preferably performed at a pH of the oil-containing wastewater of 7.2 or more, and preferably 7.5 or more. The pH is preferably 11.0 or less, and preferably 9.0 or less. This is because if the aerobic treatment is performed on the fat-and-water containing waste water having such a pH in the range, treated water with higher cleanliness can be obtained.

  The aerobic treatment is preferably performed at a temperature of the fat-containing wastewater of 20 ° C or higher, and more preferably 30 ° C or higher. 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 oil-and-fat-containing waste water is subjected to an aerobic treatment at such a temperature range, treated water 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) of 0.05 or more, more preferably 0.1 to 0.5. preferable.
The aerobic treatment is preferably carried out with the ratio of the mass of the fats and oils and the mass of phosphorus atoms (phosphorus / fats and fats) in the fat-containing wastewater being 0.01 or more, preferably 0.05 to 0.1.
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 performs two or more aerobic treatments, the first stage aerobic treatment has a dissolved oxygen content (DO) in the fat-containing wastewater of 2.0 mg / L. It is preferable to carry out so that it may become below, More preferably, it will carry out so that it may become 1.0 mg / L or less, It is further more preferable to carry out so that it may become 0.6 mg / L or less. 2. The dissolved oxygen amount (DO) in the fat and oil-containing waste water 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 0 mg / L or more. This is because treated water with higher cleanliness can be obtained.
The amount of dissolved oxygen can be measured with a conventionally known DO meter.

The aerobic processing means possessed by the apparatus of the present invention will be described.
The aerobic treatment means is not particularly limited as long as the aerobic treatment using the microbubble as described above can be performed on the oil-containing wastewater. For example, oil and fat-containing wastewater is received in a container having an aerobic bacterium that lives in an aerobic environment where oxygen is present, and the aerobic bacterium acts on this. It is preferable to have a device capable of stirring the inside of such a container.

  The aerobic treatment means possessed by the apparatus of the present invention preferably includes a mixing means for mixing the microorganisms in the aerobic treatment apparatus, the fat and oil-containing waste water, and the microbubbles. This is to obtain an appropriate stirring force. This mixing is preferably a gentle stirring force that does not cause excessive flow. For example, when the aerobic treatment means is in a tank shape, examples of the mixing means include an apparatus capable of stirring the inside of the tank, that is, a stirrer.

Conventional aerobic treatment methods using microbubbles, such as floating biological treatment methods (batch activated sludge method, continuous activated sludge method, etc.) and biofilm treatment methods (aerobic filter bed method, fluidized bed method, etc.) It is possible to use an apparatus that performs a known process.
Furthermore, it is preferable that the aerobic treatment means further includes means capable of adjusting the pH, temperature, nitrogen, phosphorus, dissolved oxygen amount, etc. of the oil-containing wastewater as described above. The pH and temperature can be adjusted by conventionally known acid and alkali addition means and heating means. Nitrogen, phosphorus, and dissolved oxygen can be supplied by a conventionally known replenishment means such as a nitrogen source.

The aerobic treatment means is preferably one that performs aerobic treatment 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 aerobic treatment is performed on the oil-containing wastewater at the front part, an aerobic treatment is further performed at the rear part. In addition, for example, there may be mentioned an embodiment in which two apparatuses are used and the fat-containing wastewater is subjected to aerobic treatment with the first apparatus and then subjected to aerobic treatment with the second apparatus.
The aerobic processing means may be one that performs aerobic processing three or more times.
In addition, when the aerobic processing means performs aerobic processing of two or more stages, microbubbles are supplied in at least one stage.
This is because when two or more aerobic treatments are performed on the oil-and-fat-containing wastewater, aerobic treated water having better water quality can be obtained.

  When aerobic treatment includes activated sludge treatment as described above, and when two or more aerobic treatments are performed, sludge discharged by activated sludge treatment or sludge discharged by aerobic treatment after two steps is used. It is preferable to supply oil and fat-containing wastewater as return sludge. This is because the purity of treated water finally obtained is further increased. That is, it is preferable that the aerobic processing means is configured to be able to accept return sludge.

In the aerobic treatment, bubbles may be generated from the surface of the treatment liquid during the treatment. When bubbles are generated, there is a possibility that the sludge flows out or the piping provided in the aerobic processing means is blocked, which is not preferable. In such a case, it is preferable that the aerobic processing means 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. It is preferable to use a nonionic surfactant antifoaming agent as the antifoaming agent because it prevents not only the generation of bubbles but also the coalescence of microbubbles.

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.
As another foam removing means, there is a method of separating and transferring the generated foam from the aerobic treatment process.

A preferred embodiment of the apparatus of the present invention will be described with reference to FIGS.
The apparatus 10 shown in FIG. 1 is an apparatus of the present invention having a microporous microbubble generator 11. Moreover, the apparatus 10 has the stirring apparatus 15 for mixing stirring as a mixing means which mixes the fat and oil containing waste water 1 and the microbubble 3. FIG.

In the apparatus 10, the micro-bubble generator 11 is provided at the lower part in the aerobic treatment tank 17. The pore type microbubble generator 11 generates the microbubble 3 by passing the pressurized air supplied from the pressurized air supply device 13 through a pore plate (not shown). A porous material such as ceramics or metal, a membrane or a filter can be used for the pore plate. In addition, it is preferable to add a surfactant in order to prevent coalescence of bubbles.
The stirring device for mixing and stirring 15 rotates the stirring blade 16 to mix the microorganisms in the aerobic treatment tank 17, the fat / oil containing waste water 1 and the microbubbles 3. The stirring by the mixing and stirring device 15 is preferably a gentle stirring force while maintaining the reaction efficiency of the aerobic treatment. This is to suppress the generation of oil and fat residues and further stabilize the bubble diameter of the microbubbles. Specifically, the stirring speed is preferably 10 to 50 mim- ¹ .

  The apparatus 20 shown in FIG. 2 is an apparatus of the present invention having a pressure dissolution type microbubble generator 21. In addition, the apparatus 20 has a mixing and stirring apparatus 15 as with the apparatus 10.

In the apparatus 20, a pressure dissolution type microbubble generator 21 is provided in the lower part of the aerobic treatment tank 17. The pressure dissolution type microbubble generator 21 generates the microbubble 3 by releasing the pressure of the pressure dissolution water 27 supplied from the pressure dissolution tank 25 with a pressure reducing valve (not shown). The pressure-dissolved water 27 supplies the oil-containing wastewater 1 in the aerobic treatment tank 17 to the pressure-dissolve tank 25 by the pump 23, and adds pressurized air 24 to this to apply high pressure (about 300 to 400 kPa). Air is dissolved.
The function and effect of the mixing and stirring apparatus 15 in the apparatus 20 are the same as those in the apparatus 10. The stirring speed of the stirring device 15 for mixing and stirring is the same as that of the device 10.

The aerobic treatment means included in the apparatus of the present invention preferably includes the microbubble generating means as described above for supplying microbubbles.
Moreover, when using an aerobic processing tank in an aerobic process, it is desirable to use the system which does not generate | occur | produce an excessive flow in a tank as a microbubble generation | occurrence | production means.

  When the apparatus of the present invention as described above is used to perform an aerobic treatment on the oil-and-fat-containing wastewater, an oil-and-fat residue is hardly generated.

The aerobic treatment step included in the method of the present invention is a step of supplying the microbubbles to the oil-containing wastewater to perform the aerobic treatment. The aerobic treatment process can be performed by the aerobic treatment means as described above.

  The apparatus of the present invention further comprises anaerobic treatment means for performing anaerobic treatment on the fat-containing wastewater to discharge the anaerobic treated water, and the aerobic treatment means supplies microbubbles to the anaerobic treated water. A means for applying an aerobic treatment is preferable.

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.
Semi-anaerobic treatment does not include conventional anaerobic digestion.

  The anaerobic treatment in the present invention can be carried out, for example, by adjusting conditions (time, pH, temperature, etc.) that cause anaerobic bacteria and microaerobic bacteria to act on oil-containing wastewater.

  In the anaerobic treatment, it is preferable that 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 is 20 hours. Two days are more preferable, and three days are more preferable. 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 as described above for the fat-containing wastewater, anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and It corresponds to the time for which at least one selected from the group consisting of aerobic bacteria is allowed to act.

  The anaerobic treatment is preferably performed with the pH of the oil-containing wastewater set to 7.2 or higher. 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 the fat-containing wastewater of 20 ° C or higher, and more preferably 30 ° C or higher. 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 waste water. Moreover, it is preferable that the density | concentration of the sulfate ion in fats and oils containing waste_water | drain is 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 oil-containing wastewater and anaerobic treatment is performed, the redox potential of the oil-containing wastewater is preferably −200 mV or less, more preferably −300 mV or less. Adjust and apply anaerobic treatment.

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

  Acceptable hexane extract concentration of oil-containing wastewater in anaerobic treatment is preferably 30 to 30,000 mg / L, more preferably 30 to 20,000 mg / L, and 30 to 10,000 mg / L. More preferably.

  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, etc.) that act on at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria on fat and oil-containing wastewater. ) Can be adjusted.

  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 and fat-containing wastewater 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. 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 to perform semi-anaerobic treatment by setting the pH of the fat-and-oil containing waste water to 7.2 or more. Further, this pH is preferably set to 11.0 or less, more preferably 8.8 or less.

  Further, the semi-anaerobic treatment is preferably performed at a temperature of the fat / oil-containing waste water of 20 ° C. or higher, and more preferably 30 ° C. or higher. 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 a fat-and-oils containing wastewater contain a sulfate ion. Moreover, it is preferable that the density | concentration of the sulfate ion in fats and oils containing waste water shall be 10-3,000 mg / L, it is more preferable to set it as 50-2,000 mg / L, and it is further referred to as 100-1,000 mg / L. preferable.

  When semi-anaerobic treatment is performed by causing microaerobic bacteria and / or aerobic bacteria to act on oil-containing wastewater, for example, a limited oxygen supply, which is different from conventionally known aeration treatment, is performed on oil-containing wastewater. Is preferred. At this time, it is preferable to perform the semi-anaerobic treatment by adjusting the redox potential of the oil-containing wastewater to +50 mV or less, more preferably -50 mV or less, and still more preferably -50 to -250 mV.

  The anaerobic treatment means possessed by the apparatus of the present invention is particularly limited as long as it is a means capable of performing the anaerobic treatment (preferably semi-anaerobic treatment) as described above on the fat-containing wastewater and discharging the anaerobic treated water. Not. For example, oil-containing wastewater is received in a sealed container having anaerobic bacteria living in an anaerobic environment without oxygen, and the anaerobic bacteria are allowed to act on this to discharge anaerobic treated water. . 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. The oil and fat-containing wastewater 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 the anaerobic treated water. What is discharged. Whatever container is used, it is preferable to have a device capable of stirring the inside thereof.

  As the anaerobic treatment means, 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 an anaerobic treatment, when the treatment is performed under the condition that decomposition by methane producers (methane fermentation) does not proceed as described above, incidental facilities such as a gas holder for storing methane gas and a desulfurization treatment device Is not necessarily required.

The anaerobic treatment means preferably further has means capable of adjusting the pH, temperature, and oxidation-reduction potential of the oil-and-fat-containing wastewater as described above. 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 applying a semi-anaerobic treatment while blowing an appropriate amount of air to the oil-containing wastewater.
Moreover, as mentioned above, when using a reaction tank in fat and oil containing waste water or an anaerobic treatment means, 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 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 may be divided into two parts, a front part and a rear part, and after anaerobic treatment is performed on the oil-containing wastewater at the front part, an anaerobic treatment is further performed at the rear part. In addition, for example, there may be mentioned an embodiment in which two apparatuses are used and the fat-containing wastewater is subjected to anaerobic treatment with the first apparatus and then subjected to anaerobic treatment with the second apparatus.
An anaerobic processing means may be a mode which performs anaerobic processing three times or more.
This is because when two or more stages of anaerobic treatment are performed on the oil-and-fat-containing wastewater, treated water having better water quality can be obtained by further applying aerobic treatment means to the obtained anaerobic treated water.

It is preferable that the anaerobic treatment means is configured to be able to accept the return sludge generated in the aerobic treatment means. This is because when the returned sludge is received and treated together with the oil-and-fat-containing wastewater, treated water having better water quality can be obtained by subjecting the obtained anaerobic treated water to further aerobic treatment.
The apparatus of the present invention preferably has an anaerobic treatment means as described above.

  It is preferable that the method of the present invention further includes an anaerobic treatment step of subjecting the fat and oil-containing wastewater to anaerobic treatment and discharging anaerobic treated water. The anaerobic treatment step can be performed by the anaerobic treatment means described above.

The aerobic treatment means of the present invention is preferably a means for supplying an aerobic treatment by supplying microbubbles to the anaerobic treated water. This is because oil and fat residues are less likely to occur.
At this time, the conditions for subjecting the anaerobic treated water to the aerobic treatment (the bubble diameter of the microbubbles, the frequency in the bubble diameter distribution, the time, pH, temperature, etc.) Preferably they are the same.
Moreover, it is preferable that the aerobic processing means which the apparatus of this invention has includes the mixing means which mixes the anaerobic processing water, the microorganisms in an aerobic processing apparatus, and microbubble. As this mixing means, a mixing means for mixing the microorganisms in the aerobic treatment apparatus, the oil-containing waste water, and the microbubbles can be used.

  The aerobic treatment step provided in the present invention is preferably a step in which microbubbles are supplied to the anaerobic treatment water to perform an aerobic treatment. Such an aerobic treatment process can be performed by the aerobic treatment means as described above.

A preferred embodiment of the apparatus of the present invention will be described with reference to FIG.
FIG. 3 is a conceptual diagram for explaining a preferred embodiment of the apparatus of the present invention.
In FIG. 3, the apparatus 30 of the present invention includes an adjustment tank 32 that receives the oil-containing wastewater 1, an aggregated polymer addition means 56 that adds the aggregated polymer to the oil-containing wastewater 1 in the adjustment tank 32, and a PAC addition means that adds PAC. 54, the pressurized levitation tank 34 for solid-liquid separation of the oil-containing wastewater 1 into the floss 58 and the separated water 60, the dispersion tank 36 for dispersing the floss 58 and discharging the dispersed water 66, and the floss 58 or the dispersed water. An anaerobic treatment tank 38 that performs anaerobic treatment on 66 and discharges the anaerobic treatment water 68; an aerobic treatment tank 40 that performs an aerobic treatment on the anaerobic treatment water 68 and discharges the aerobic treatment water 72; An activated sludge treatment tank 42 for performing activated sludge treatment on the aerobic treated water 72 and discharging the activated sludge treated water 78; and a precipitation tank 44 for solid-liquid separation of the activated sludge treated water 78 into treated water 82 and return sludge 80. Have.

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 treatment tank 38 corresponds to an anaerobic treatment means that the apparatus of the present invention preferably has.
The aerobic treatment tank 40 corresponds to an aerobic treatment means included in the apparatus of the present invention.
The activated sludge treatment tank 42 corresponds to an activated sludge treatment means that the apparatus of the present invention preferably has.
The settling tank 44 corresponds to a settling means that the apparatus of the present invention preferably has.

  In addition, the apparatus 30 of the present invention uses at least a part of the return sludge 76 discharged from the aerobic treatment tank 40 and / or the return sludge 80 discharged from the sedimentation tank 44 to the adjustment tank 32, the dispersion tank 36, and the anaerobic treatment. Sludge return means 52, 62, 70 and 74 that can be returned to the tank 38 and the aerobic treatment tank 40, respectively.

The adjustment tank 32 stores the oil-containing wastewater 1, and the apparatus 30 uses a structure having a storage part. The oil and fat-containing waste water 1 is received and stored in the adjustment tank 32 and can be supplied to the pressure 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 to supply the return sludge, the PAC, and the agglomerated polymer 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.
Also, the sludge return means 52 connects the return sludge 76 and return sludge 80 in the aerobic treatment tank 40 and the settling tank 44 to the adjustment tank 32 by piping, and the return sludge 76 and return sludge 80 are acted on by a pump. The return sludge 76 and the return sludge 80 can be added to the oil-containing wastewater 1 inside the adjustment tank 32.

The apparatus of the present invention preferably has a concentration means for concentrating the fat and oil contained in the fat and oil-containing wastewater and discharging it as a concentrate (also referred to as floss), and discharging a portion other than the concentrate as separated water. Further, it is preferable that the concentrate can be supplied to the dispersing means, and the separated water can be supplied to the aerobic treatment process in the aerobic treatment means or to the vicinity of the inlet or the outlet thereof.
Moreover, when an activated sludge process is included after an aerobic process, it is preferable to supply isolation | separation water just before performing an activated sludge process, for example, the inflow port vicinity of an activated sludge tank.
Furthermore, it is preferable to obtain a concentrate obtained by concentrating the concentration of the oil and fat contained in the oil and fat-containing wastewater 10 times or more by the concentration means. The degree of concentration is preferably 40 to 50 times.
As such a concentration means, for example, a pressurized levitation tank 34 can be used.

  The pressurized levitation tank 34 receives the oil-containing wastewater 1 (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 treatment tank 38. Further, the separated water 60 can be supplied to the inlet or outlet of the activated sludge treatment tank 42.

  The method of the present invention preferably includes a concentration step of concentrating the oil and fat contained in the oil and fat-containing wastewater and discharging it as a concentrate, and discharging a portion other than the concentrate as separated water. The concentration step can be performed by the concentration means as described above.

  The apparatus of the present invention preferably has a dispersing means for receiving the concentrate, stirring it and discharging it as dispersed water. Moreover, it is preferable that the dispersion | distribution means is comprised so that the return sludge from a fat residue and a sludge return means can be received. That is, it is preferable that a dispersion | distribution means receives fats and oil residue and / or return sludge as needed, stirs a concentrate with these, and discharges it as dispersion water. As such a dispersing means, for example, a dispersion tank 36 can be used.

The dispersion tank 36 receives the oil residue 64 and / or the return sludge (76, 80), and stirs the floss 58 together with these to discharge as dispersed 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 return sludge 80 in the aerobic treatment tank 40 and the settling tank 44 to the dispersion tank 36 with piping, and the return sludge 76 and 80 is connected by a pump. It is configured so that it can be transferred and added to the floss 58 inside the dispersion vessel 36.

  The method of the present invention preferably has a dispersion step of accepting the concentrate, stirring it and discharging it as dispersed water. The dispersing step can be performed by the dispersing means as described above.

The anaerobic treatment tank 38 receives the dispersed water 66 and / or the floss 58 and anaerobic treatment by at least one action selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria. And anaerobic treated water 68 is discharged.
The anaerobic treatment 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. In addition, when processing on the conditions which do not carry out methane fermentation, there may not be incidental facilities, such as a gas holder for storing methane gas, and a desulfurization processing apparatus, and the apparatus 30 does not provide.

Further, the anaerobic treatment tank 38 is configured to receive the returned sludge by the sludge returning means 70. Specifically, the sludge return means 70 connects the return sludge 76 and the return sludge 80 in the aerobic treatment tank 40 and the settling tank 44 to the anaerobic treatment tank 38 by piping, and the return sludge 76 and The return sludge 80 is transferred, and the return sludge 76 and the return sludge 80 can be added to the floss 58 or the dispersed water 66 inside the anaerobic treatment tank 38.
In addition, the anaerobic treatment 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 treatment tank 40 has a storage part, and is configured to be able to supply microbubbles into the storage part. Moreover, it is comprised so that an inside can be divided into 2 parts or 3 parts. The aerobic treatment 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 the remaining reaction The liquid is discharged as aerobic treated water 72. Note that a microbubble generator (not shown) is disposed in the lower portion of the aerobic treatment tank 40 so that the microbubbles can be supplied into the tank. Moreover, the stirring apparatus for mixing stirring for mixing the inside of an aerobic processing tank as needed is arrange | positioned. The aerobic treatment tank 40 is provided with an air supply apparatus for generating microbubbles such as a pressurized air supply apparatus and a pressurized dissolution tank.
In addition, the aerobic treatment tank 40 is configured to receive the returned sludge by the sludge return means 74. Specifically, the sludge return means 74 connects the return sludge 76 and the return sludge 80 in the aerobic treatment tank 40 and the settling tank 44 to the aerobic treatment tank 40 from the discharge port, and connects the return sludge 76 and the aerobic treatment tank 40 by the action of a pump. 80 is transported and added to the vicinity of the inlet of the aerobic treatment tank 40.
In addition, the aerobic treatment tank 40 is configured to transfer and discharge the reaction liquid in the vicinity of the outlet as return sludge (return sludge 76).

  The aerobic treatment means of the apparatus of the present invention preferably includes an activated sludge treatment means for performing activated sludge treatment on the aerobic treated water and discharging the activated sludge treated water. An activated sludge treatment tank 42 can be used as the activated sludge treatment means.

  The activated sludge treatment tank 42 is a structure that can supply air (oxygen) to the inside and can be agitated, and the inside is divided into three. The activated sludge treatment 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. Moreover, the activated sludge treatment tank 42 may supply microbubbles into the tank as an oxygen source.

  The aerobic treatment step included in the method of the present invention preferably includes an activated sludge treatment step of performing activated sludge treatment on the aerobic treated water and discharging the activated sludge treated water. The activated sludge treatment step can be performed by the activated sludge treatment means as described above.

The aerobic treatment means included in the apparatus of the present invention preferably includes precipitation means for solid-liquid separation of the aerobic treated water into treated water and sludge. In addition, the aerobic treatment in the present invention preferably includes 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 flocated by the settling tank. Means for separation by natural sedimentation. A sedimentation tank for performing such activated sludge treatment may be included as a sedimentation means.
The precipitation means is not particularly limited as long as it is a means capable of precipitating the sludge contained in the aerobic treated water. For example, a precipitation tank 44 can be used.

  The sedimentation tank 44 is configured to receive activated sludge treated water 78 (which may include separated water 60). And it is comprised so that a sediment can be discharged | emitted as the return sludge 80 and a supernatant can be discharged | emitted as the treated water 82. FIG.

  The aerobic treatment step provided in the method of the present invention preferably includes a precipitation step in which aerobic treated water (including activated sludge treated water) is solid-liquid separated into treated water and sludge. The precipitation step can be performed by the precipitation means as described above.

The apparatus of the present invention may have sludge return means for supplying the return sludge generated in the aerobic treatment means and / or the precipitation means to oil-containing wastewater (including concentrate or dispersed water) or anaerobic treated water. preferable.
As the sludge return means, for example, from a return sludge discharge port in the aerobic treatment means and / or the precipitation means, a storage part (for example, the adjustment tank 32) for storing oil-containing wastewater, a dispersion means, an anaerobic treatment means, or an aerobic treatment Examples include means for connecting up to the processing means with piping and transferring the returned sludge by the action of the pump. Examples of such sludge return means include sludge return means 52, 62, 70 or 74. The amount of return sludge added to oil-containing wastewater (including concentrate or dispersed water) or anaerobic treated water by the sludge return means is such that the SS concentration after addition is 50 to 5,000 mg-SS / L. The amount is preferably 500 to 5,000 mg-SS / L.

  The apparatus of the present invention preferably has sludge return means for adding return sludge to the concentrate. This is because oil and fat residues are less likely to be generated. Moreover, it is because decomposition | disassembly of fats and oils becomes easier and the treated water with a higher cleanliness is obtained. In addition, compared with the case where the return sludge is added to the anaerobic treatment means, the return sludge added to the concentrate in the dispersion means is less likely to generate oil residue, and the oil content is more easily decomposed. Because it becomes.

  The method of the present invention further includes a sludge return step for supplying the return sludge generated in the aerobic treatment and / or the precipitation step to the fat-containing wastewater (including concentrate or dispersed water) or anaerobic treated water. preferable. In the anaerobic treatment, it is preferable to treat the returned sludge generated in the aerobic treatment and / or the precipitation step together with fat and oil-containing wastewater (including concentrate or dispersed water). Such a sludge returning step can be performed by the sludge returning means.

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

  The fat and oil containing waste water 1 discharged | emitted from a food factory is processed on the process conditions shown below using the apparatus 30 shown in FIG. In addition, only the process of processing the fat-and-oils containing waste_water | drain 1 by the pressurization floating tank 34 is made into a batch type, and the other process performs the continuous process. The amount of treated water in the continuous treatment is 3 L / day.

  In the adjustment tank 32, the PAC and the agglomerated polymer are added by the PAC addition unit 54 and the agglomerated polymer addition unit 56. Here, the amount of PAC added is 300 mg / L with respect to the oil-containing wastewater 1 in the adjustment tank 32. Furthermore, the addition amount of the agglomerated polymer is 1 mg / L with respect to the oil-containing wastewater 1 in the adjustment tank 32.

  Next, the fat and oil-containing wastewater 1 to which PAC and agglomerated polymer are added is treated in the pressure levitation tank 34. Then, the entire amount of the obtained floss 58 is supplied to the dispersion tank 36. At this time, the volume ratio of the floss 58 and the separated water 60 is 1:39. The whole amount of the separated water 60 is supplied to the inlet of the activated sludge treatment tank 42. That is, after the separated water 60 is merged with the aerobic treated water 72, it is treated in the activated sludge treatment tank 42.

  Next, the floss 58 is processed in the dispersion tank 36. In the dispersion tank 36, NaOH is appropriately added to the received floss 58 to maintain the pH in the tank at 8.5 to 9.5. Moreover, the temperature inside the tank is maintained at 50 ° C., and the inside is mechanically stirred. Furthermore, the residence time in the dispersion tank 36 is 1 hour.

  The anaerobic treatment tank 38 is divided into three parts by providing a partition inside the tank. Further, the tank is sealed, and adjusted by adding NaOH appropriately so that the pH in the tank becomes 8.5. Moreover, it adjusts so that the temperature in a tank may be 37 degreeC, and also mechanically stirs the inside. The residence time in the anaerobic treatment tank 38 is 4 days.

  Further, the return sludge 80 discharged from the settling tank 44 is supplied to the vicinity of the inlet of the anaerobic treatment tank 38. The return sludge 80 is transferred by the sludge return means 70 and supplied so that the SS concentration of the dispersed water 66 at the transfer destination is 150 mg-SS / L.

  The aerobic treatment tank 40 is divided into three parts by providing a partition inside the tank. Moreover, it adjusts by adding NaOH or a sulfuric acid suitably so that pH in a tank may be set to 8.0. Moreover, it adjusts so that the temperature in a tank may be 37 degreeC. Moreover, it stirs, ventilating on the setting conditions that the dissolved oxygen concentration of the liquid in a tank is 0.5 mg / L. Furthermore, the residence time in the aerobic treatment tank 40 is 5 days.

  A microbubble generator and a stirring device for mixing and stirring are disposed in the aerobic treatment tank 40. Moreover, since the aerobic processing tank 40 is divided | segmented, the microbubble generator and the stirring apparatus for mixing stirring are arrange | positioned in each division tank.

  As the microbubble generator, the same pressure dissolution type microbubble generator (made by Auratech, model: OM4-MDG-045) as in FIG. 2 is used. The microbubbles are supplied so that the dissolved oxygen concentration in the anaerobic treated water 68 in the aerobic treatment tank 40 is 0.5 mg / L. Here, the microbubbles generated in each example include those within the bubble diameter range shown in Table 1. The frequency (number basis) in the bubble size distribution of the microbubbles is adjusted so that the microbible within the bubble size range shown in Table 1 is 50% or more. In addition, the measurement of the bubble diameter and the frequency (number basis) in bubble diameter distribution of a microbubble uses the nanoparticle diameter distribution measuring apparatus (The Shimadzu Corporation make, model: SALD-7500 nano).

As the mixing and stirring apparatus, the mixing and stirring apparatus 15 shown in FIG. 2 is used. One stirring device 15 for mixing and stirring is disposed in each tank obtained by dividing the inside of the tank into three partitions, and stirs the anaerobic treated water 68 and the microbubbles. The stirring speed at this time is 10 to 25 min ⁻¹ .

  In the activated sludge treatment tank 42, NaOH or sulfuric acid is appropriately added and adjusted so that the pH in the tank becomes 7.8. Moreover, it adjusts so that the temperature in a tank may be 37 degreeC. Furthermore, it stirs, ventilating on the setting conditions that the dissolved oxygen concentration of the liquid in a tank is 3.0 mg / L. The residence time in the activated sludge treatment tank 42 is 6 hours. In addition, ventilation | gas_flowing in a tank is performed by supplying air (bubble diameter: 800-1200 micrometers) from the diffuser pipe (illustration omitted) which the activated sludge process tank 42 has.

Under such conditions, the oil-containing wastewater 1 is treated, and the n-hexane extract concentration of the treated water 82 is measured. The measuring method of n-hexane extract concentration is as described above. In addition, the n-hexane extract density | concentration of the fat-and-oils containing waste water 1 used by a present Example is 500 mg / L.
Moreover, the fat residue produced | generated in the aerobic processing tank 40 is collect | recovered as the generation amount of a fat residue, and the mass is measured.
The results are shown in Table 1.

As shown in Table 1, in all Examples, the n-hexane extract concentration in the treated water 82 is 5 mg / L at the maximum. Moreover, the generation amount of fat residue becomes 30 mg-wet / L at the maximum.
On the other hand, in Comparative Examples 1 and 2, the maximum amount of oil residue is 300 mg-wet / L.

1: Oil and fat-containing wastewater, 3: Microbubbles, 10, 20, 30: Apparatus, 11: Fine pore type microbubble generator, 13: Pressurized air supply apparatus, 15: Stirring apparatus for mixing and stirring, 16: Stirring blade, 17, 40: Aerobic treatment tank, 21: Pressurized dissolution type microbubble generator, 23: Pump, 24: Pressurized air, 25: Pressurized dissolution tank, 27: Pressurized dissolved water, 32: Adjustment tank, 34 : Pressurized flotation tank, 36: dispersion tank, 38: anaerobic treatment tank, 42: activated sludge treatment tank, 44: sedimentation tank, 52, 62, 70, 74: sludge return means, 54: PAC addition means, 56: Coagulated polymer addition means, 58: Floss, 60: Separated water, 64: Oil residue, 66: Dispersed water, 68: Anaerobic treated water, 72: Aerobic treated water, 76, 80: Return sludge, 78: Activated sludge treatment Water, 82: treated water

Claims (6)

  The processing method of fat and oil containing wastewater provided with the aerobic processing process which supplies a microbubble to fat and oil containing wastewater and performs aerobic processing. Furthermore, it comprises an anaerobic treatment step of performing anaerobic treatment on the fat-containing wastewater to discharge anaerobic treated water,
The method for treating fat-and-oil-containing wastewater according to claim 1, wherein the aerobic treatment step is a step of supplying the microbubbles to the anaerobic treatment water to perform an aerobic treatment.   The processing method of the fat and oil containing wastewater of Claim 1 or 2 with which the said aerobic treatment process includes the mixing process which mixes the said fat and oil containing wastewater or the said anaerobic treated water, and the said microbubble.   An apparatus for treating fat-containing wastewater having aerobic treatment means for supplying microbubbles to fat-containing wastewater to perform aerobic treatment. Furthermore, it has an anaerobic treatment means for performing anaerobic treatment on the oil-containing wastewater to discharge anaerobic treated water,
The fat-and-oil-containing wastewater treatment apparatus according to claim 4, wherein the aerobic treatment means is means for supplying the microbubbles to the anaerobic treated water to perform an aerobic treatment. The processing apparatus of the fat and oil containing waste water of Claim 4 or 5 in which the aerobic processing means contains the mixing means which mixes the said fat and oil containing waste water or the said anaerobic treated water, and the said microbubble.

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