JP2015071157A - Animal and vegetable oils-containing wastewater treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment system capable of stably and preferably decomposing and removing an oil content of wastewater containing animal and vegetable oils, in biological treatment using an activated sludge aeration tank.SOLUTION: The wastewater treatment system for treating wastewater containing animal and vegetable oils by biological treatment includes the activated sludge aeration tank. The activated sludge aeration tank includes: an outflow port 14 for flowing out sludge-containing liquid in the activated sludge aeration tank; and a shielding plate 16 for preventing outflow of animal and vegetable oils floating on the sludge-containing liquid in the activated sludge aeration tank from the outflow port 14.

Description

  The present invention relates to a wastewater treatment system containing animal and vegetable oils.

Organic wastewater containing high concentrations of animal and vegetable oils is discharged from food factories, kitchens, cosmetics manufacturing factories, and the like. Such organic wastewater is often discharged as floating oil, and in that case, it is removed by floating separation. However, it is difficult to completely remove animal and vegetable oils only by floating separation.
In addition, when the oil recovered by separation is treated as sludge, there is also a problem that the working environment deteriorates due to the handling and odor. When the treatment target is a dispersion oil or an emulsified oil, pressurized flotation separation may be employed. However, the pressure levitation separation has a problem that stable processing cannot be performed due to load fluctuation or the like.

Against this backdrop, for example, Patent Documents 1 and 2 propose a method for increasing the oil decomposing ability using a special oil-degrading bacterium.
It is also known to treat wastewater containing animal and vegetable oils by biological treatment using an activated sludge aeration tank or the like.

Japanese Patent Laid-Open No. 2002-018481 JP 2002-233890 A

  However, in biological treatment using a conventional activated sludge aeration tank or the like, it has been difficult to sufficiently remove oil from wastewater containing animal and vegetable oils.

  The present invention has been made in view of the above circumstances, and provides a treatment system capable of stably and satisfactorily decomposing and removing oil from wastewater containing animal and vegetable oils in biological treatment using an activated sludge aeration tank. Objective.

The present invention has the following configuration.
[1] A wastewater treatment system for biologically treating wastewater containing animal and vegetable oils, having an activated sludge aeration tank, and the activated sludge aeration tank drains the sludge containing liquid in the activated sludge aeration tank An animal and vegetable oil-containing wastewater treatment system comprising an outlet and a shielding plate that prevents the animal and vegetable oil floating on the sludge-containing liquid in the activated sludge aeration tank from flowing out from the outlet.
[2] The animal and vegetable oil-containing wastewater treatment system according to [1], further including a separation tank for solid-liquid separation of the sludge-containing liquid flowing out from the activated sludge aeration tank after the activated sludge aeration tank.
[3] The animal and vegetable oil-containing wastewater treatment system according to [1] or [2], wherein a microorganism-immobilized carrier is introduced into the activated sludge aeration tank.
[4] The animal and vegetable oil-containing wastewater treatment system according to [3], wherein the microorganism-immobilized carrier has polypropylene as a main component.
[5] The animal and plant oil-containing wastewater treatment system according to [3] or [4], wherein the microorganism-immobilized carrier is a cylindrical shape that satisfies the following conditions (A) to (C).
(A) Outer diameter: 3-15mm
(B) Inner diameter: 2 to 13 mm
(C) Length: 3-20mm
[6] The animal and vegetable oil-containing wastewater treatment system according to any one of [3] to [5], wherein the microorganism-immobilized carrier includes at least one of a carbonaceous filler and a glassy filler.
[7] The animal and plant oil-containing wastewater treatment system according to [6], wherein a ratio of the carbonaceous filler and the glassy filler to the total mass of the microorganism-immobilized carrier is 0.1% or more and less than 5%.
[8] The animal and plant oil-containing wastewater treatment system according to [6] or [7], wherein the carbonaceous filler and the glassy filler have a length of 50 μm to 3 mm and a thickness of 1 μm to 25 μm.
[9] The animal and plant oil-containing wastewater according to any one of [3] to [8], wherein pores are formed on the surface of the microorganism-immobilized carrier, and the microorganism-immobilized carrier satisfies the following formula (1): Processing system.
A / B ≧ 0.8 (1)
A: Sum of pore volumes having a diameter of 1-1000 μm B: Sum of pore volumes having a diameter of 0.003-1000 μm

According to the animal and vegetable oil-containing wastewater treatment system of the present invention, in the biological treatment using the activated sludge aeration tank, the oil content of the wastewater containing the animal and vegetable oil can be decomposed and removed stably and favorably.
In the present invention, “animal and vegetable oil” means animal oil and / or vegetable oil.

It is a schematic block diagram which shows an example of the animal and vegetable oil containing waste water treatment system of this invention. It is a schematic block diagram which shows the activated sludge aeration tank and separation tank with which the processing system of FIG. 1 is provided. It is a schematic plan view of the activated sludge aeration tank of FIG. It is the graph which plotted the hexane extract substance density | concentration of the treated water sampled from the sedimentation tank with respect to the elapsed days from the operation start of an activated sludge aeration tank. It is the graph which plotted the filter paper filtration amount of the sludge containing liquid sampled from the activated sludge aeration tank with respect to the elapsed days from the operation start of the activated sludge aeration tank.

Hereinafter, the present invention will be described in detail.
<Animal and vegetable oil-containing wastewater treatment system>
FIG. 1 is a schematic configuration diagram showing an example of an animal and vegetable oil-containing wastewater treatment system (hereinafter also simply referred to as “treatment system”) of the present invention. FIG. 2 is a schematic configuration diagram showing an activated sludge aeration tank and a solid-liquid separation tank (separation tank) included in the treatment system of FIG.

In the treatment system of FIG. 1, first, wastewater discharged from food factories, kitchens, cosmetics manufacturing factories, etc., containing high-concentration animal and vegetable oils is stored in the raw water tank as raw water, and the raw water is taken from this raw water tank. Introduce into the flotation tank. Subsequently, the floating separation treated water after a part of the oil is separated in the floating separation tank is introduced into the adjustment tank, and the flow rate, concentration, and the like of the floating separation treated water are adjusted.
Next, the floating separation treated water that has passed through the adjustment tank is introduced into the activated sludge aeration tank, and the floating separation treated water is biologically treated in the activated sludge aeration tank. Thereafter, the sludge mixed liquid in the activated sludge aeration tank is introduced into the solid-liquid separation tank and separated into activated sludge and treated water. At least a part of the activated sludge obtained by the separation is returned to the activated sludge aeration tank, and the treated water is discharged.

[Activated sludge aeration tank]
The activated sludge aeration tank 10 in this example processes floating separation treated water (hereinafter referred to as “treatment target water”) that has passed through the adjustment tank, and the activated sludge aeration tank 10 contains the treatment target water. be introduced. The activated sludge aeration tank 10 is provided with an aeration pipe 11 for aeration (aeration) of air supplied from a blower (not shown) into the activated sludge aeration tank 10. Further, in the activated sludge aeration tank 10, the activated sludge 12 that performs biological treatment and the microorganisms contained in the activated sludge 12 are immobilized, and a large number of microorganisms that flow in the activated sludge aeration tank 10 are immobilized. Carrier 13 is charged. In this example, the sludge mixed liquid (including water to be treated and activated sludge) from the activated sludge aeration tank 10 is solid-liquid separated in the membrane separation tank 20 including the membrane unit 21.

In the upper part of the tank wall of the activated sludge aeration tank 10, an outlet 14 is formed for overflowing the sludge mixed liquid in the tank to the membrane separation tank 20 after (after) the activated sludge aeration tank 10. In addition, in the vicinity of the outlet 14 in the activated sludge aeration tank 10, a carrier outflow prevention for preventing the microorganism-immobilized support 13 put in the activated sludge aeration tank 10 from flowing out of the activated sludge aeration tank 10. A net 15 is provided.
In addition, as will be described in detail later, in this example, the animal and vegetable oils floating in the sludge mixed liquid in the activated sludge aeration tank 10 are sufficiently biological in the tank in the vicinity of the outlet 14 in the activated sludge aeration tank 10. A shielding plate 16 is provided for preventing the outflow from the outlet 14 to the membrane separation tank 20 after the activated sludge aeration tank 10 (the latter stage) without being subjected to special treatment.

(Microorganism immobilization carrier)
In the present embodiment, a carrier mainly composed of polypropylene is used as the microorganism-immobilized carrier 13 used in the activated sludge aeration tank 10. By using a carrier mainly composed of polypropylene, the oil content of wastewater containing animal and vegetable oils can be decomposed and removed stably and satisfactorily. Further, in the subsequent solid-liquid separation, a sludge-containing liquid having a good membrane separation property can be obtained.
In addition, a main component means the component contained exceeding 50 mass%.

Examples of the microorganism-immobilized carrier mainly composed of polypropylene include a carrier molded from a composition containing a thermoplastic resin component containing at least polypropylene and a filler. Examples of the shape of the microorganism-immobilized carrier include a columnar shape, a cylindrical shape, a spherical shape, a cubic shape, and the like, and in particular, when the shape is cylindrical, in terms of adhesion of microorganisms, fluidity in an activated sludge aeration tank, and the like. preferable.
Examples of the resin other than polypropylene constituting the thermoplastic resin component include polyethylene, polyvinyl chloride, ethylene-vinyl acetate copolymer resin, polystyrene, and the like, and one or more of these can be used.

The polypropylene as the main component of the carrier is not particularly limited as long as it is polymerized with propylene as the main component, and for example, commercially available general polypropylene can be used. Also, propylene, acid-modified polypropylene, recycled polypropylene, etc., which are copolymerized with a small amount of ethylene for modification can be used.
Examples of commercially available general polypropylene include those manufactured by Nippon Polychem Co., Ltd., trade names “Novatech PP BC4”, “Novatech PP BC4L”, and the like. Examples of commercially available acid-modified polyolefins include Mitsui Chemical Co., Ltd., trade name “Admer”, Sanyo Kasei Co., Ltd., trade name “Yumex” and the like.

  From the viewpoint of carrier strength, the microorganism-immobilized carrier preferably contains 70% by mass or more of polypropylene, more preferably more than 95% by mass, in 100% by mass of the microorganism-immobilized carrier.

The microorganism-immobilized carrier preferably contains a filler. The filler is a natural or synthetic material having a shape such as granular, rod-like, or fiber-like, and is made of a material that does not melt or decompose at the molding temperature of polypropylene or other thermoplastic resin used as necessary. Can be used. The filler is used for the purpose of improving the strength of the microorganism-immobilized carrier, increasing the surface area of the microorganism-immobilized carrier, and improving the affinity with microorganisms.
The surface area of the microorganism-immobilized carrier is preferably 400 m ² / m ³ or more, more preferably 4000 m ² / m ³ or more, from the viewpoint of affinity with microorganisms.

  As the filler, it is preferable to use at least one of a carbonaceous filler mainly made of carbon and a glassy filler mainly made of glass. Examples of the carbonaceous filler include activated carbon, activated carbon fiber, and carbon fiber. Examples of the vitreous filler include glass having a granular shape, a rod shape, a plate shape, a fiber shape, and the like. When at least one of the carbonaceous filler and the glassy filler is used, the strength of the microorganism-immobilized carrier is greatly improved by adding a small amount. In addition, the degree of roughening of the carrier surface is remarkably increased, the amount of microorganisms attached to the surface of the microorganism-immobilized carrier is increased, and the treatment efficiency of waste water containing animal and vegetable oils is excellent.

  In addition, the microorganism-immobilized support to which the carbonaceous filler and the glassy filler are not added floats while enclosing bubbles for a while after the addition to the activated sludge aeration tank, whereas the carbonaceous filler and the glassy filler The microorganism-immobilized carrier to which at least one of the above is added floats slightly immediately after the addition of these fillers to the activated sludge aeration tank, but immediately starts good flow. This is presumably based on the fact that the surface of the microorganism-immobilized carrier to which at least one of the carbonaceous filler and the glassy filler is added is made hydrophilic.

  When a glassy filler is used alone as the filler, it is preferable in that the adhesion of microorganisms to the surface of the microorganism-immobilized carrier is further improved. When the carbonaceous filler and the glassy filler are used in combination, the adhesion of microorganisms is further improved. The reason why the combined effect is manifested in this way is not clear, but there is a possibility that the affinity of the carbonaceous filler to the microorganism and the hydrophilicity of the glassy filler to the microorganism function synergistically.

The filler is preferably added in a range of 0.1% by mass or more and less than 5.0% by mass in 100% by mass of the microorganism-immobilized support, and is added in a range of 0.3% by mass or more and less than 3.0% by mass. More preferably, it is particularly preferable to add in the range of 1.0 mass% or more and less than 2.5 mass%.
If the proportion of the filler is not less than the lower limit of the above range, the effect of improving the strength and affinity with microorganisms can be expected, and if it is not more than the upper limit of the above range, the moldability when molding the microorganism-immobilized carrier can be improved. It can be maintained well and the cost due to the filler can also be suppressed.

  When the carbonaceous filler and the glassy filler are used in combination, the mass ratio of the carbonaceous filler to the mass of the glassy filler is preferably from 0.02 to 2, and preferably from 0.1 to 1, from the viewpoint of better adhesion of microorganisms. More preferred is 0.1 to 0.5. When the carbonaceous filler and the glassy filler are used in combination, the proportion of the carbonaceous filler in 100% by mass of the microorganism-immobilized carrier is preferably 2% by mass or less, and more preferably 1% by mass or less. Moreover, 0.1 mass% or more is preferable and 0.3 mass% or more is more preferable. On the other hand, the proportion of the glassy filler in 100% by mass of the microorganism-immobilized carrier is preferably less than 5% by mass, and more preferably 3% by mass or less. Moreover, 0.1 mass% or more is preferable and 1 mass% or more is more preferable.

  When a fiber is used as the filler, both the effect of improving the strength of the microorganism-immobilized carrier and the effect of roughening the carrier surface are further improved.

The filler preferably has a length of 50 μm to 3 mm, and more preferably 100 μm to 2 mm, from the viewpoint of improving the strength of the microorganism-immobilized carrier and improving the affinity with the microorganism. The thickness of the filler is preferably 1 to 25 μm and more preferably 5 to 20 μm from the viewpoint of improving the strength of the microorganism-immobilized carrier.
Here, the length of the filler is the length along the longitudinal direction of the filler, and the thickness is the maximum diameter of the surface perpendicular to the longitudinal direction of the filler. When the vertical surface is a perfect circle, the maximum diameter is the diameter, and when it is a shape other than a perfect circle, the maximum diameter is the diameter of a perfect circle circumscribing the shape.
In the present specification, the length and thickness of the filler are the average values of the values measured by microscopic observation of any 15 of the fillers contained in the microorganism-immobilized carrier, as “filler length and thickness”. Adopted as “sa”.

  The microorganism-immobilized carrier can be easily produced by mixing, melting, and extrusion-molding polypropylene, if necessary, other thermoplastic resin, and more preferably a filler. It can be manufactured without the need for special equipment or after-treatment, and is excellent in cost.

  When polypropylene is used for molding the microorganism-immobilized carrier and other thermoplastic resin raw materials used as necessary, pellets are excellent in handleability. Moreover, when adding a filler, it is preferable to use the master pellet shape | molded with resin and a filler. When master pellets are used, the master pellets are not used. Compared to the method of melt-kneading polypropylene and other thermoplastic resins to be used as needed and fillers cut to the required length, and extrusion molding, Grinding can be suppressed. Therefore, the strength of the obtained microorganism-immobilized carrier is very excellent, and the handleability is remarkably excellent.

When producing master pellets, it is preferable to use a filler having a length of 3 to 12 mm in consideration of passing through steps such as melt-kneading and cutting in an extruder. It is more preferable to use a filler.
Master pellets are manufactured by, for example, guiding a filler roving consisting of thousands of filaments to an impregnation die, uniformly impregnating the molten resin between the filaments, and then cutting into a predetermined length to form pellets. it can.

  As a filler, when using both a carbonaceous filler and a glassy filler, as a master pellet, one containing both a carbonaceous filler and a glassy filler can be used, or a pellet containing a carbon filler and Also, a pellet containing a glassy filler can be used in combination.

  Specific examples of the master pellet include, for example, a long fiber glass fiber reinforced polypropylene resin (trade name “Funkster LR25Z”, glass fiber content = 50 mass%) manufactured by Chisso Corporation, carbon manufactured by Mitsubishi Rayon Co., Ltd. Examples thereof include fiber reinforced polypropylene resin (trade name “Pyrofil PP-C20”, carbon fiber content = 20 mass%).

The microorganism-immobilized carrier includes, as optional components, specific gravity adjusting materials such as calcium carbonate, talc, zeolite, barium sulfate, titanium oxide, potassium titanate, and aluminum hydroxide; azodicarbonamide (ADCA) for making porous , Dinitrosopentamethylenetetramine (DPT), carbonate-based foaming agents and foaming aids; various additives may be included. Examples of the additive include an additive mainly composed of liquid paraffin and a nonionic surfactant for improving dispersibility with the pellet when a powder-based foaming agent is used.
The optional component may be added directly during the production of the microorganism-immobilized carrier, or may be added as a resin pellet containing the optional component.

  The shape of the microorganism-immobilized carrier is preferably cylindrical as described above. The size of the cylindrical microorganism-immobilized carrier is, for example, an outer diameter of 3 to 15 mm, an inner diameter of 2 to 13 mm, and a length of 3 to 20 mm. Adhesion of microorganisms and fluidity in an activated sludge aeration tank Etc. are preferable. More preferably, the outer diameter is 6 to 12 mm, the inner diameter is 5 to 10 mm, and the length is 5 to 15 mm.

It is preferable that pores are formed on the surface of the microorganism-immobilized carrier, and the microorganism-immobilized carrier satisfies the following formula (1).
A / B ≧ 0.8 (1)
A: Total pore volume having a diameter of 1-1000 μm B: Total pore volume having a diameter of 0.003-1000 μm In order to increase the activity of the microorganism-immobilized support, among the microorganisms attached to the support, It is effective to improve the amount of microorganisms that work effectively. For that purpose, it is effective to increase the volume of pores having a diameter of 1 μm or more. When the pore volume having a diameter of less than 1 μm is large, the surface area (specific surface area) per volume of the microorganism-immobilized support increases, but the amount of microorganisms that work effectively hardly increases. Therefore, the specific surface area is insufficient as an indicator of the activity of the microorganism-immobilized carrier.
Therefore, the above A / B is used as an index of the activity of the microorganism-immobilized carrier.
The microorganism-immobilized carrier more preferably satisfies the following formula (2), and more preferably satisfies the following formula (3). Further, the upper limit of A / B may be 1.
A / B ≧ 0.83 (2)
A / B ≧ 0.85 (3)

In this specification, the pore volume was measured by a mercury intrusion porosimeter method using “Autopore 9520 type” manufactured by Shimadzu Corporation. The whole measurement range of the pore diameter was 0.003-1000 μm and 1-1000 μm, and A and B were calculated.
The pore volume was measured after the microorganism-immobilized support was sufficiently dried.

When the diameter of the pores is excessively large, the microorganism-immobilized carrier floats by biting bubbles, which is not preferable. In this respect, the upper limit of the pore diameter is preferably 1000 μm, and more preferably 700 μm. On the other hand, as described above, the lower limit of the pore diameter is preferably 1 μm, more preferably 2 μm, and more preferably 4 μm.
Therefore, the ratio of the total pore volume having a diameter within the range of the upper limit and the lower limit is 80% or more with respect to B (the total pore volume having a diameter of 0.003 to 1000 μm). Preferably, it is 83% or more, more preferably 85% or more. The proportion may be 100%.

  The pores on the surface of the microorganism-immobilized carrier are formed by adding a filler to the microorganism-immobilized carrier or adding the above-mentioned foaming agent, foaming aid, additive and the like. A / B can be controlled by adjusting the type and size of the filler used, or adjusting the type and amount of the foaming agent, foaming aid, additive, and the like.

  Since such a microorganism-immobilized carrier is mainly composed of polypropylene and preferably contains a filler, the oil content of wastewater containing animal and vegetable oils can be decomposed and removed stably and satisfactorily. Further, in the subsequent solid-liquid separation, a sludge-containing liquid having a good membrane separation property can be obtained.

(Processing method)
Biological treatment in the activated sludge aeration tank 10 is performed by aerating the inside of the activated sludge aeration tank 10 with the diffusion tube 11 and flowing the microorganism-immobilized carrier 13 to which microorganisms adhere. As processing conditions, the following conditions are preferable, for example.
-Input amount of the microorganism-immobilized carrier: 10 to 20% by volume of the capacity of the activated sludge aeration tank.
-Water temperature of activated sludge aeration tank: 15-37 degreeC.
-Amount of dissolved oxygen in the activated sludge aeration tank: 2.0 mg / L or more.
-BOD volumetric load: 0.5-3.0 (kg-BOD / m < ³ > * day).
-Sludge density | concentration (MLSS): 10-20000 (mg / L).

(Shield)
As described above, an outlet 14 is formed in the upper part of the tank wall of the activated sludge aeration tank 10 in FIG. 2 to overflow the sludge mixed solution in the tank to the membrane separation tank 20 after the activated sludge aeration tank 10. A shielding plate 16 is provided in the vicinity of the outlet 14 in the tank. The shielding plate 16 floats on the liquid surface of the sludge mixed liquid in the activated sludge aeration tank 10 even when the animal and vegetable oil floating on the liquid surface of the liquid to be processed sent from the previous stage (in this example, the adjustment tank) is floated. It is provided to prevent it from flowing out from the outlet 14 to the membrane separation tank 20 after (after) the activated sludge aeration tank 10 without being sufficiently biologically treated. As shown in FIG. 2, the shielding plate 16 has a semi-cylindrical shape in this example, and a part in the height direction protrudes above the liquid level, and the remaining part in the height direction is located below the liquid level. Thus, it is provided so that the surface direction becomes a substantially vertical direction. From the viewpoint of more effectively suppressing the outflow of animal and vegetable oils, the liquid surface height H and liquid surface depth D of the shielding plate are each preferably 5 cm or more, and more preferably 20 cm or more. More preferably, it is 30 cm or more. The upper limit of the liquid surface height H and the liquid surface depth D of the shielding plate is, for example, 100 cm. The liquid surface height H and liquid surface depth D of the shielding plate are set according to the scale such as the depth of the activated sludge aeration tank 10, the flow state of the active-containing liquid and the microorganism-immobilized carrier, the behavior of bubbles, etc. it can. Further, as shown in the plan view of FIG. 3, the animals and plants are such that both end portions 16 a and 16 b are attached to the inner wall of the activated sludge aeration tank 10 so that the shielding plate 16 surrounds the outlet 14. It is preferable in that oil outflow is more effectively suppressed and the oil can be decomposed and removed stably and satisfactorily.

As described above, since the activated sludge aeration tank of the treatment system of the present embodiment has a shielding plate, the animal and plant oil floating in the sludge-containing liquid in the activated sludge aeration tank is not sufficiently treated and is discharged from the outlet. It is prevented from flowing out. Therefore, in the activated sludge aeration tank, the oil content of the wastewater containing animal and vegetable oils can be decomposed and removed stably and favorably.
Moreover, the processing system of the present embodiment has an activated sludge aeration tank 10 in which a microorganism-immobilized carrier mainly composed of polypropylene is charged. Therefore, in the activated sludge aeration tank 10, the oil content of the treatment target liquid containing animal and vegetable oils can be effectively decomposed and removed, and depending on the treatment conditions in the activated sludge aeration tank 10, the oil concentration is, for example, several tens It is also possible to reduce to ppm. Thus, if it is a sludge containing liquid with which the density | concentration of oil was reduced, solid-liquid separation can fully be carried out also in the membrane separation tank provided with separation membranes, such as a hollow fiber membrane.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
A model solution obtained by adding commercially available salad oil (Nisshin Oilio Co., Ltd.) to the synthesized sewage having the composition and analysis values shown in Table 1 was used as the treatment target solution of the activated sludge aeration tank. Salad oil was added as a hexane extract substance so that it might become 300 mg / L per liter of synthetic sewage. Synthetic sewage and salad oil were added in separate lines. As the microorganism-immobilized carrier, as shown in Table 2, a cylindrical carrier formed of a resin composition containing polypropylene as a main component and carbon fibers and glass fibers as fillers was used. The contents of carbon fiber and glass fiber in Table 2 are values relative to 100% by mass of the microorganism-immobilized support.

As shown in Table 2, the outer diameter and length of the used microorganism-immobilized carrier are both 10 mm and the inner diameter is 7.2 mm.
The length of the carbon fiber (carbonaceous filler) in the microorganism-immobilized carrier was 3 mm and the thickness was 17 μm, and the length of the glass fiber (glassy filler) was 3 mm and the thickness was 7 μm.
The A / B of the microorganism-immobilized carrier was 0.86.
The length and thickness of the filler and the A / B for the microorganism-immobilized carrier were determined by the method described above.

Using such a model solution and a microorganism-immobilized carrier, water treatment was performed in an activated sludge aeration tank shown in FIG. 2 and a sedimentation tank (not shown) under the biological conditions shown in Table 3. The height H above the liquid level of the shielding plate was 10 cm, and the depth D below the liquid level was 5 cm.
And the treated water was sampled from the sedimentation tank for every fixed elapsed days, and the hexane extract substance density | concentration in treated water was analyzed by JISK0102. The results are shown in the graph of FIG.
Moreover, the sludge containing liquid was sampled from the activated sludge aeration tank for every fixed elapsed days, and the filter paper filtration amount which is an index of membrane separation was measured. The results are shown in FIG.
The amount of filter paper filtration is No. for sludge containing liquid. This is the amount of filtrate when filtered for 5 minutes using 5C (JIS P 3801) filter paper.

[Example 2]
As shown in Table 2, water treatment was performed in the same manner as in Example 1 except that a cylindrical carrier formed of polypropylene was used as the microorganism-immobilizing carrier, and the same evaluation was performed. The results are shown in FIGS. In addition, as shown in Table 2, the outer diameter and the length of the used microorganism-immobilized carrier are both 10 mm and the inner diameter is 7.2 mm.

[Example 3]
Water treatment was performed in the same manner as in Example 1 except that the microorganism-immobilized carrier was not used in the activated sludge aeration tank, and the same evaluation was performed. The results are shown in FIGS.

  From the graph of FIG. 4, when a microorganism-immobilized support mainly composed of polypropylene is used in an activated sludge aeration tank, it is stable and favorable from the beginning of the elapsed days as compared with the case where a microorganism-immobilized support is not used. It was found that treated water with reduced hexane extractables was obtained. Moreover, from the graph of FIG. 5, when the amount of filter paper filtration was also excellent and it processed by providing a membrane separation tank after an activated sludge aeration tank (after stage), it was suggested that membrane separation property is also favorable.

[Comparative Example 1]
The model liquid was treated with water using the same activated sludge aeration tank as in Example 1 except that no shielding plate was installed.
As a result, the oil in the model liquid floated on the surface of the sludge treatment liquid in the activated sludge aeration tank, and flowed out from the outlet to the sedimentation tank without being treated in the activated sludge aeration tank.
From this, it was found that the oil component could not be sufficiently treated in the activated sludge aeration tank when no shielding plate was installed. In addition, when a membrane separation tank is provided after the activated sludge aeration tank and the membrane treatment is carried out, it is suggested that the membrane is blocked by the oil flowing out from the activated sludge aeration tank and the membrane treatment cannot be performed stably. It was.

10 activated sludge aeration tank 12 activated sludge 13 microorganism immobilization support 16 shielding plate

Claims (9)

A wastewater treatment system for biologically treating wastewater containing animal and vegetable oils,
Has an activated sludge aeration tank,
The activated sludge aeration tank is configured to discharge the sludge-containing liquid in the activated sludge aeration tank and the outflow from the outlet of the animal and plant oil floating on the sludge-containing liquid in the activated sludge aeration tank. Animal and vegetable oil-containing wastewater treatment system having a shielding plate to prevent.   The animal and vegetable oil-containing wastewater treatment system according to claim 1, further comprising a separation tank for solid-liquid separation of the sludge-containing liquid flowing out of the activated sludge aeration tank after the activated sludge aeration tank.   The animal and vegetable oil-containing wastewater treatment system according to claim 1 or 2, wherein a microorganism-immobilized carrier is introduced into the activated sludge aeration tank.   The animal and vegetable oil-containing wastewater treatment system according to claim 3, wherein the microorganism-immobilized carrier has polypropylene as a main component. The animal and vegetable oil-containing wastewater treatment system according to claim 3 or 4, wherein the microorganism-immobilized carrier has a cylindrical shape that satisfies the following conditions (A) to (C).
(A) Outer diameter: 3-15mm
(B) Inner diameter: 2 to 13 mm
(C) Length: 3-20mm   The animal and vegetable oil-containing wastewater treatment system according to any one of claims 3 to 5, wherein the microorganism-immobilized carrier includes at least one of a carbonaceous filler and a glassy filler.   The animal and vegetable oil-containing wastewater treatment system according to claim 6, wherein a ratio of the carbonaceous filler and the glassy filler to the total mass of the microorganism-immobilized carrier is 0.1% or more and less than 5%.   The animal and vegetable oil-containing wastewater treatment system according to claim 6 or 7, wherein the carbonaceous filler and the glassy filler have a length of 50 µm to 3 mm and a thickness of 1 µm to 25 µm. The animal and vegetable oil-containing wastewater treatment system according to any one of claims 3 to 8, wherein pores are formed on the surface of the microorganism-immobilized carrier, and the microorganism-immobilized carrier satisfies the following formula (1).
A / B ≧ 0.8 (1)
A: Total pore volume having a diameter of 1-1000 μm B: Total pore volume having a diameter of 0.003-1000 μm

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