JP2019130504A - Water treatment method and water treatment device - Google Patents

Abstract

To provide a water treatment method and a water treatment device capable of suppressing an amount of generation of sludge while stabilizing treatment of a membrane separation activated sludge tank in treatment of water to be treated containing at least one of organic SS components and oil and fat.SOLUTION: The water treatment method has an anaerobic treatment step in which water to be treated containing at least one of organic SS components and fat is subjected to an anaerobic treatment in an anaerobic fluidized bed reaction tank 12 having a stirrer 26, and an aerobic treatment step in which the anaerobic treated water obtained by the anaerobic treatment is subjected to an aerobic treatment in a membrane separation activated sludge tank 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water treatment method and a water treatment apparatus for water to be treated containing at least one of an organic SS component and fats and oils.

  Compared with the activated sludge method, the membrane separation activated sludge method (MBR method) is becoming widespread because of the advantages such as the ability to reduce sedimentation basins and the quality of treated water. However, when the suspended matter (SS) concentration of the water to be treated is high, the sludge retention time in the membrane separation activated sludge method is shortened, membrane clogging is likely to occur, and the membrane chemical cleaning frequency is increased. . Even when fats and oils are contained in the water to be treated, clogging of the film is likely to occur as in the case where the SS concentration is high. Therefore, in general, SS components, oils and fats are removed by solid-liquid separation (coagulation sedimentation method, pressurized flotation method, etc.) as a pretreatment for the membrane separation activated sludge method, and then treated by the membrane separation activated sludge method. However, there is a problem that a large amount of sludge is generated from the solid-liquid separation process.

  Patent Document 1 proposes a treatment method for aerobic biological treatment, not solid-liquid separation treatment, as a pretreatment for membrane separation activated sludge process for organic wastewater containing fats and oils. Due to the high conversion rate to sludge, there is still a need to reduce excess sludge.

JP 2012-239940 A

  The object of the present invention is to suppress the generation amount of sludge while stabilizing the treatment of the membrane separation activated sludge tank in the treatment of the water to be treated containing at least one of the organic SS component and fats and oils. The object is to provide a water treatment method and a water treatment apparatus.

  The present invention relates to an anaerobic treatment step in which an anaerobic fluidized bed type reaction tank having a stirrer is anaerobically treated for water to be treated containing at least one of an organic SS component and fats and oils, and the anaerobic treatment. An anaerobic treatment step of aerobically treating the anaerobic treated water obtained by the above in a membrane separation activated sludge tank.

  In the water treatment method, it is preferable that the SS concentration contained in the water to be treated is 400 mg / L or more, and the SS concentration is reduced to less than 400 mg / L in the anaerobic treatment step.

  In the water treatment method, the fat concentration contained in the water to be treated is preferably 100 mg / L or more, and the fat concentration is preferably reduced to less than 100 mg / L in the anaerobic treatment step.

  In the anaerobic fluidized bed reactor in the water treatment method, it is preferable to use a gel carrier as a carrier.

  In addition, the present invention provides an anaerobic fluidized bed reaction tank having an agitation device for anaerobically treating water to be treated containing at least one of an organic SS component and fats and oils, and the anaerobic treatment. It is a water treatment apparatus provided with the membrane separation activated sludge tank for carrying out the aerobic treatment of the anaerobic treated water obtained by this.

  In the water treatment apparatus, the SS concentration contained in the water to be treated is preferably 400 mg / L or more, and the SS concentration is preferably reduced to less than 400 mg / L by the anaerobic treatment.

  In the water treatment apparatus, the fat concentration contained in the water to be treated is preferably 100 mg / L or more, and the fat concentration is preferably reduced to less than 100 mg / L by the anaerobic treatment.

  In the anaerobic fluidized bed reactor in the water treatment apparatus, a gel carrier is preferably used as the carrier.

  ADVANTAGE OF THE INVENTION According to this invention, in the process of the to-be-processed water containing at least 1 among organic SS component and fats and oils, the generation amount of sludge can be suppressed, stabilizing the process of a membrane separation activated sludge tank. .

It is a schematic structure figure showing an example of the water treatment equipment concerning the embodiment of the present invention. It is a graph which shows the time-dependent change of the suction pressure (kPa) of the membrane separation part in the membrane separation activated sludge process of Example 1 and Comparative Example 1.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  An example of a water treatment apparatus according to an embodiment of the present invention is schematically shown in FIG.

  The water treatment apparatus 1 is an anaerobic fluidized bed type reaction having a stirring device 26 for anaerobically treating water to be treated containing at least one of an organic suspended solids (SS) component and fats and oils. The tank 12 and the membrane separation activated sludge tank 14 for carrying out the aerobic process of the anaerobic process water obtained by the anaerobic process are provided. The water treatment apparatus 1 may include a water tank 10 to be treated for storing the water to be treated.

  In the water treatment apparatus 1 of FIG. 1, a water treatment pipe 18 is connected to the inlet of the water tank 10 to be treated. The outlet of the water tank 10 to be treated and the inlet of the anaerobic fluidized bed reaction tank 12 are connected by a water pipe 20 to be treated via a pump 16. The outlet of the anaerobic fluidized bed reactor 12 and the inlet of the membrane separation activated sludge tank 14 are connected by an anaerobic treated water pipe 22. A membrane 30 is installed in the membrane separation activated sludge tank 14, and a treated water pipe 24 is connected to the membrane 30. In the anaerobic fluidized bed reaction tank 12, for example, a carrier 28 to which anaerobic microorganisms are attached in the form of a biofilm is placed, and a stirring device 26 having stirring blades and the like is installed. The anaerobic fluidized bed type reaction tank 12 is a stirring type anaerobic flow for conducting biological treatment by passing water to be treated under anaerobic conditions while flowing the carrier 28 in the tank by stirring by the stirring device 26. It is a bed type reaction tank.

  The operation of the water treatment method and the water treatment apparatus 1 according to this embodiment will be described.

  The treated water containing at least one of the organic SS component and fat is stored in the treated water tank 10 as needed through the treated water pipe 18 and then anaerobic through the treated water pipe 20 by the pump 16. The solution is sent to the ionic fluidized bed reactor 12. The carrier 28 is put into the anaerobic fluidized bed type reaction tank 12 before or after the start of liquid feed of the water to be treated. In the anaerobic fluidized bed reactor 12, the biological treatment is performed under anaerobic conditions while the carrier 28 and the water to be treated are stirred by the stirring device 26 (anaerobic treatment step).

  The anaerobic treated water obtained by the anaerobic treatment is sent to the membrane separation activated sludge tank 14 through the anaerobic treated water pipe 22, and the membrane separation activated sludge tank 14 is subjected to aerobic conditions (aeration, agitation, etc.) by the microorganisms in the tank. Biological treatment is carried out with oxygen supply (aerobic treatment step). The aerobic treated water is separated from the sludge by the membrane 30 (separation process). The separated aerobic treated water is discharged as treated water through the treated water pipe 24 and the sludge in the membrane separation activated sludge tank 14 is concentrated. The

  In the water treatment method and the water treatment apparatus 1 according to the present embodiment, a stirring type anaerobic fluidized-bed reaction tank and membrane separation are performed on water to be treated containing at least one of an organic SS component and fats and oils. In combination with the activated sludge tank, anaerobic treatment is performed in the anaerobic fluidized bed reaction tank 12 having a stirring device without performing solid-liquid separation treatment, and then anaerobic treatment of the anaerobic treated water in the membrane separation activated sludge tank 14 is performed. . Thereby, in the process of the to-be-processed water containing at least 1 among organic SS component and fats and oils, the generation amount of sludge can be suppressed, stabilizing the process of a membrane separation activated sludge tank.

<Anaerobic treatment process>
[Reactor form of anaerobic fluidized bed water treatment]
The anaerobic fluidized bed reaction tank 12 has a high contact efficiency between the water to be treated and the carrier 28, and can be treated with water to be treated having a high fat concentration and a high SS concentration. An anaerobic fluidized bed reactor is used. The stirring type anaerobic fluidized bed reaction tank 12 is not particularly limited as long as it is of a type in which the carrier flows by stirring with a stirring device.

  When the water to be treated contains at least one of organic SS components and fats and oils, solid-liquid separation treatment (coagulation sedimentation method, pressurized flotation method, etc.) and aerobic organisms as pretreatment of membrane separation activated sludge method An anaerobic biological treatment may be performed instead of the treatment. However, organic treated water containing at least one of organic SS components and oils and fats is treated with a conventional upward flow anaerobic fluidized bed reactor in which the carrier in the tank is not stirred by a stirring device. When trying to do so, SS components or oils and fats adhere to the carrier, and the carrier floats up or the adhesion of methane fermentation bacteria capable of decomposing organic matter is inhibited, so a stable high load treatment is performed for a long period of time. I couldn't. As a pretreatment of the membrane separation activated sludge method, the present inventors include at least one of an organic SS component and fats and oils by performing a treatment using a stirring type anaerobic fluidized bed reactor. It has been found that in the treatment of water to be treated, the amount of sludge generated can be suppressed while stabilizing the treatment of the membrane separation activated sludge tank.

  In the case of the stirring type anaerobic fluidized bed reactor 12, the carrier 28 is stirred by the stirring device 26 and shear force is applied to the carrier 28, so that adhesion of SS components or oils and fats to the carrier 28 is suppressed. it is conceivable that. As a result, the floating of the carrier 28 is suppressed, and methane fermentation bacteria and the like adhere to the carrier 28, or methane fermentation bacteria and the like are immobilized inside the carrier 28. In the accompanying anaerobic biological treatment, it is considered that a high-load treatment that is stable for a long time can be performed. Therefore, before the treatment by the anaerobic biological treatment or the membrane separation activated sludge method, the pretreatment for separating the SS component or the oil and fat from the organic water to be treated, for example, the coagulation sedimentation treatment, the pressure flotation treatment or the like is not performed. Also good. That is, the water to be treated containing a high concentration organic SS component or oil / fat can be directly introduced into the anaerobic fluidized bed reactor 12. Moreover, since the to-be-processed water is stirred by the stirring apparatus 26, it is suppressed that the inlet_port | entrance etc. of the anaerobic fluidized bed reaction tank 12 are obstruct | occluded with SS component or fats and oils.

  The stirring device 26 may be any device configuration that can stir the carrier 28 in the anaerobic fluidized bed reaction tank 12, and is not particularly limited. Examples of the stirring device 26 include a stirring device having a motor, a stirring blade, a shaft connecting the motor and the stirring blade, and the like. Since the anaerobic fluidized bed reaction tank 12 has the stirring device 26 for stirring the carrier 28, when the carrier 28 is taken out from the anaerobic fluidized bed reaction tank 12 and to the anaerobic fluidized bed reaction tank 12. When the carrier 28 is taken in, the carrier can be taken out and taken in the anaerobic fluidized bed reactor 12 as evenly as possible (as uniformly as possible).

  Although it is preferable to install a draft tube (not shown) inside the anaerobic fluidized bed reaction tank 12 in terms of improving the fluidity of the carrier 28, the draft tube is not necessarily installed. The draft tube is a cylindrical tube such as a cylindrical tube that is installed substantially vertically in the anaerobic fluidized bed reaction tank 12 and is open at the top and bottom.

  The water treatment apparatus 1 may include, for example, a screen (not shown) installed so as to surround the anaerobic treated water outlet of the anaerobic fluidized bed reaction tank 12. This screen makes it possible to suppress the outflow of the carrier 28 from the anaerobic fluidized bed reactor 12. Examples of the screen include a wedge wire screen, a wire net, and a punching metal.

[Carrier]
The carrier for attaching anaerobic microorganisms in the form of a biofilm is not particularly limited as long as it is a carrier conventionally used in anaerobic biological treatment. Examples of the carrier include a plastic carrier, a sponge carrier, a gel carrier and the like. In particular, by using a gel-like carrier, methane-fermenting bacteria that do not produce a polymer polymer enter into the pores of the three-dimensional network structure of the gel-like carrier, or adhere due to the shape, charge, etc. of the gel-like carrier. It is easy and effective for holding a biofilm, and the fluidity of the carrier by stirring is high, so that a higher load treatment is possible compared to a plastic carrier and a sponge carrier. The gel carrier is not particularly limited, and examples thereof include a water-absorbing polymer gel carrier containing polyvinyl alcohol, polyethylene glycol, polyurethane and the like.

  The shape of the carrier 28 is not particularly limited, but is preferably spherical or cubic (cube), rectangular, cylindrical or the like having a diameter of about 0.5 mm to 20 mm. In particular, a spherical or cylindrical gel carrier having a diameter of about 3 to 8 mm is preferable.

  In order to form a fluidized state inside the anaerobic fluidized bed reactor 12, the specific gravity of the carrier 28 is at least larger than 1.0 and the true specific gravity is 1.1 or more, or the apparent specific gravity is 1.01 or more. Is preferred.

  The amount of the carrier 28 introduced into the anaerobic fluidized bed reactor 12 is preferably in the range of 10 to 50% with respect to the volume of the anaerobic fluidized bed reactor 12. When the input amount of the carrier 28 is less than 10% with respect to the volume of the anaerobic fluidized bed reaction tank 12, the reaction rate may be small. The treated water may be short-passed due to sludge blockage or the like, resulting in poor treated water quality.

  The sedimentation rate of the carrier 28 is preferably 100 to 150 m / hr. When the sedimentation speed of the carrier 28 is less than 100 m / hr, the carrier 28 floats up and easily flows out of the anaerobic fluidized bed type reaction tank 12, and when it exceeds 150 m / hr, the fluidized state deteriorates and water to be treated May have a short pass or agitation energy may increase.

[Anaerobic microorganism adhesion carrier]
The biofilm is a membranous structure in which anaerobic microorganisms and products such as exopolysaccharides produced by the anaerobic microorganisms are assembled, and has a film thickness of at least 10 μm, preferably a film thickness of 20 μm or more. It is what has. The film thickness is a thickness from the surface of the carrier 28 and is an average value of 10 to 20 carriers 28. For products such as extracellular polysaccharides, polysaccharides can be extracted from biofilms using alkali, and the sugar concentration in the extract can be measured by the Anthrone method. Products such as exopolysaccharides are considered to be sticky and affect the adhesion of biofilms, for example, preferably 20 ppm or more in biofilms, 50 ppm or more More preferably.

[Operating conditions of anaerobic fluidized bed reactor]
In this embodiment, when biologically treating the organic treated water, the pH of the treated water is preferably in the range of 6.0 to 8.5, more preferably in the range of 6.5 to 7.5. The pH of the water to be treated is adjusted, for example, by supplying the pH adjusting agent from a pH adjusting agent supply pipe (not shown) to the water tank 10 to be treated in which the water to be treated is stored. If the pH of the water to be treated is outside the above range, the organic substance decomposition reaction rate by biological treatment may decrease.

  Examples of the pH adjuster include acid agents such as hydrochloric acid and alkali agents such as sodium hydroxide, and are not particularly limited. Further, the pH adjusting agent may be, for example, sodium bicarbonate having a buffering action, a phosphate buffer or the like.

  In the present embodiment, when biologically treating organic treated water, for example, it is preferable to add a nutrient to the treated water from the viewpoint of maintaining good degradation activity of anaerobic microorganisms. Although it does not restrict | limit especially as a nutrient, For example, a carbon source, a nitrogen source, a phosphorus source, other inorganic salts (salts, such as nickel, cobalt, iron), etc. are mentioned.

  In this embodiment, it is preferable to adjust the temperature of the anaerobic fluidized bed reactor 12 so that the water temperature is 20 ° C. or higher. Usually, when it is lower than 20 ° C., the decomposition reaction rate tends to decrease. The method for adjusting the temperature of the water temperature in the anaerobic fluidized bed reaction tank 12 is not particularly limited. For example, a heater or the like is installed in the anaerobic fluidized bed reaction tank 12 to provide a heater or the like. The method of adjusting the water temperature in the anaerobic fluidized bed reaction tank 12 with the heat of this is mentioned.

<Aerobic treatment process>
[film]
For the water treatment method and the water treatment apparatus 1 of the present embodiment, a submerged membrane activated sludge method that is a membrane separation activated sludge method, an outside tank type membrane separation activated sludge method, or the like can be applied. Further, as the membrane (separation membrane) 30 to be used, any of a flat membrane, a hollow fiber membrane, a cross flow membrane and the like can be applied.

  The material of the film 30 is not particularly limited, and examples thereof include fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), polyethylene (PE), polyvinyl chloride (PVC), and ceramics. In view of strength, chemical resistance, etc., a fluororesin or ceramic is preferable.

  The pore diameter of the membrane 30 is not particularly limited, but is preferably 0.5 μm or less, and more preferably in the range of 0.01 μm or more and 0.1 μm or less.

  The permeation flow rate of the membrane 30 during operation may be operated at, for example, about 0.1 to 1.0 m / day, and is preferably operated at 0.2 to 0.6 m / day. If the permeation flow rate of the membrane 30 during operation is less than 0.1 m / day, the membrane area to be installed may become excessive, and if it exceeds 1.0 m / day, clogging of the membrane is likely to occur. There is a case.

[Operating conditions of membrane separation activated sludge tank]
As a treatment condition of the membrane separation activated sludge tank 14 in the membrane separation activated sludge method, the sludge concentration may be, for example, 15,000 mg / L or less, and preferably 3,000 to 10,000 mg / L. Good. If the sludge concentration is less than 3,000 mg / L, the quality of the treated water may deteriorate, and if it exceeds 15,000 mg / L, clogging of the membrane is likely to occur.

The load of the aerobic membrane separation activated sludge tank 14 may be operated at, for example, 1.5 kg BOD / m ³ / day or less, and preferably in the range of 0.1 to 1.0 kg BOD / m ³ / day. Is preferred. If the load on the membrane separation activated sludge tank 14 is less than 0.1 kg BOD / m ³ / day, the reaction tank volume may become excessive, and if it exceeds 1.5 kg BOD / m ³ / day, the quality of treated water deteriorates. In addition, clogging of the film is likely to occur.

  The sludge load (BOD-SS load) in the membrane separation activated sludge tank 14 may be, for example, in the range of 0.01 to 0.15 kg BOD / SS / day. When the sludge load (BOD-SS load) in the membrane separation activated sludge tank 14 is out of the proper range, the quality of treated water and the clogging of the membrane are likely to occur.

  The pH in the membrane separation activated sludge tank 14 may be adjusted to be in the range of 6.0 to 8.5, for example, and is preferably adjusted to be in the range of 6.5 to 7.5.

  The DO (dissolved oxygen) concentration in the membrane separation activated sludge tank 14 may be, for example, 0.5 mg / L or more, and is preferably in the range of 1.5 to 3.5 mg / L.

  In the membrane separation activated sludge tank 14, at least one of a nutrient source, a nitrogen source and a phosphorus source may be added. Nutrient sources include trace metals such as nitrogen, phosphorus, alkali metals such as sodium, potassium, calcium, and magnesium, and metals such as iron, manganese, and zinc in order for microorganisms to decompose and grow organic matter. At least one of the classes. As the nitrogen source, urea, ammonia salt or the like may be added from the outside. As the phosphorus source, phosphate and phosphoric acid may be added from the outside. Moreover, you may add the nutrient source required in the membrane separation activated sludge tank 14 in advance, for example in the anaerobic fluidized bed reaction tank 12 or the to-be-treated water tank 10 grade | etc.,.

<Treatment water to be treated>
The water to be treated in the water treatment method and the water treatment apparatus 1 of the present embodiment contains at least one of organic SS components and fats and oils, for example, a food production factory, an electronics industry factory, and a pulp production Water containing organic substances (oils and fats, organic suspended substances (SS), and organic substances other than oils and suspended substances) discharged from factories and chemical factories. When the water to be treated contains both an organic SS component and fats and oils, the water treatment method and the water treatment apparatus 1 of the present embodiment are more effective.

  The SS component in the water to be treated is an insoluble substance contained in the water to be treated, and examples thereof include biodegradable organic substances such as starch and cellulose, inorganic substances such as diatomaceous earth, sand and metals. The water treatment method and the water treatment apparatus 1 of this embodiment according to this embodiment are particularly effective for organic treated water containing an organic SS component that can be biodegraded.

  The fats and oils in the water to be treated are substances extracted to the normal hexane side by mixing the water to be treated and normal hexane, and examples thereof include biodegradable animal and vegetable oils and mineral oils. The water treatment method and the water treatment apparatus 1 of the present embodiment are particularly effective for organic treated water containing biodegradable animal and vegetable oils and the like.

  Organic substances other than fats and SS components are BOD components other than fats and SS components and are biodegradable organic substances such as soluble proteins, saccharides, amino acids, alcohols, organic acids, fatty acids and the like. It is done.

  The oil / fat concentration of the water to be treated is determined by the following method, for example, in accordance with JIS K0102, as the normal hexane extract substance concentration. First, an appropriate amount (about 200 to 1,000 mL) of water to be treated is put into a separatory funnel, a methyl orange solution is added dropwise, and hydrochloric acid is added dropwise until the color of the solution changes to red. Then, adding 40 mL of normal hexane and shaking vigorously for 2 minutes was repeated twice. After separating only the normal hexane layer, filtration and dehydration were performed, and normal hexane was volatilized at 80 ° C. Obtain extract material. And the normal hexane extract substance density | concentration is calculated | required from the mass of the obtained normal hexane extract substance, and the mass of the input organic physical waste water.

  The SS concentration (suspended substance concentration) is, for example, measured according to JIS K0102, and is the weight of the residue when dried at 105 ° C. for 2 hours. The organic SS concentration is measured as a loss on ignition (a decrease upon ignition at 600 ° C. for 30 minutes).

  The stirring type anaerobic fluidized bed reactor 12 can be treated with water to be treated having a high fat concentration or SS concentration, but the fat concentration of the water to be treated is, for example, 100 mg / L or more. Yes, preferably 100 mg / L to 1000 mg / L. Moreover, SS concentration of to-be-processed water is 400 mg / L or more, for example, Preferably it is 400 mg / L-2000 mg / L.

  In the water treatment method and the water treatment apparatus 1 of the present embodiment, when the water to be treated contains an organic SS component, it is preferable to reduce the organic SS concentration of anaerobic treated water to less than 400 mg / L by anaerobic treatment. . When treated water contains fats and oils, it is preferable to reduce the fat and oil concentration of anaerobic treated water to less than 100 mg / L by anaerobic treatment. When the water to be treated contains an organic SS component and fats and oils, it is preferable to reduce the organic SS concentration of anaerobic treated water to less than 400 mg / L and reduce the fat concentration to less than 100 mg / L by anaerobic treatment.

  That is, in the water treatment method and the water treatment apparatus 1 of the present embodiment, the water to be treated contains an SS component, the SS concentration contained in the water to be treated is 400 mg / L or more, and the SS concentration is 400 mg / L in the anaerobic treatment step. It is preferable to reduce to less than L.

  In the water treatment method and the water treatment apparatus 1 of the present embodiment, the water to be treated contains fats and oils, the fat and oil concentration contained in the water to be treated is 100 mg / L or more, and the fat and oil concentration is less than 100 mg / L in the anaerobic treatment step. It is preferable to reduce.

  In the water treatment method and the water treatment apparatus 1 of the present embodiment, the water to be treated contains SS components and fats and oils, the SS concentration contained in the water to be treated is 400 mg / L or more, and the fats and oils concentration contained in the water to be treated. Is 100 mg / L or more, and it is preferable to reduce the SS concentration to less than 400 mg / L and the fat concentration to less than 100 mg / L in the anaerobic treatment step.

  By making at least one of the organic SS concentration and the fat concentration of the anaerobic treated water by the anaerobic treatment, the membrane is less likely to be clogged in the aerobic treatment step by the membrane separation activated sludge tank at the subsequent stage. Become.

<Treatment water>
With the water treatment method and the water treatment apparatus 1 of the present embodiment, the SS concentration of treated water (aerobic treated water) can be reduced to 2 mg / L or less. Or the fats and oils concentration of treated water (aerobic treated water) can be reduced to 5 mg / L or less.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Example 1>
[Target treated water]
Food factory wastewater (COD _Cr concentration of 1,000 to 5,000 mg / L) was used as water to be treated. The SS concentration during the test of the used food factory wastewater was 200 to 800 mg / L (maximum 1,500 mg / L, average 430 mg / L), and the fat concentration was 50 to 200 mg / L (maximum 260 mg / L, average 110 mg / L). L), and the amount of water was 40 to 60 m ³ / day. Since the ratio of the organic SS concentration to the SS concentration of the water to be treated is 99% or more, all the SSs of the water to be treated can be regarded as organic SS. The SS concentration / COD _Cr concentration of the water to be treated was 0.07 to 0.36 (average 0.18), and the fat concentration / COD _Cr concentration was 0.01 to 0.08 (average 0.05).

[Test method]
An anaerobic fluidized bed reactor having a volume of 30 m ³ was used. Spherical polyvinyl alcohol gel-like carrier (pore diameter 4-20 μm, diameter 4 mm, specific gravity 1.025, sedimentation rate 4 cm / sec) was charged 30% with respect to the volume of the anaerobic fluidized bed reactor, and the stirring blade The carrier was constantly flowed by stirring the inside of the tank with a stirring device having A membrane separation activated sludge tank with a volume of 95 m ³ was used, and a hollow fiber membrane made of polyvinylidene fluoride (PVDF) was used as the membrane.

<Comparative Example 1>
The treatment was performed in the same manner as in Example 1 except that the treatment was performed without using the anaerobic fluidized bed reactor.

[Test results]
Table 1 shows the average water quality of treated water and anaerobic treated water in Example 1. In an anaerobic fluidized bed reaction tank, the organic SS concentration and the fat concentration were reduced to 200 mg / L and 46 mg / L, respectively, and allowed to flow into the subsequent membrane separation activated sludge tank. FIG. 2 shows changes over time in the suction pressure (kPa) of the membrane separation part in the membrane separation activated sludge treatment of Example 1 and Comparative Example 1. In Comparative Example 1, the suction pressure increased to −10 to −12 kPa in about 40 days. An increase in suction pressure indicates clogging of the membrane, and in situations where the suction pressure tends to increase, chemical cleaning of the membrane must be performed frequently. On the other hand, in Example 1, the period until the suction pressure reached −10 kPa was about 130 days, which is three times or more that of Comparative Example 1, and the clogging of the film could be improved. Further, the conversion rate to sludge was 0.3 g-SS / g-BOD (0.2 g-SS / g-CODCr) in Comparative Example 1, whereas 0.08 g-SS / in Example 1. It became g-BOD (0.05g-SS / g-CODCr), and it was possible to reduce the generation amount of sludge to 1/3 or less.

  Thus, in the treatment of water to be treated containing at least one of the organic SS component and fats and oils by the water treatment method and treatment apparatus of the examples, the sludge is stabilized while stabilizing the treatment of the membrane separation activated sludge tank. It was confirmed that the generation amount of can be suppressed.

  DESCRIPTION OF SYMBOLS 1 Water treatment apparatus, 10 to-be-treated water tank, 12 anaerobic fluidized bed reaction tank, 14 membrane separation activated sludge tank, 16 pump, 18, 20 to-be-treated water piping, 22 anaerobic treated water piping, 24 treated water piping, 26 stirring Device, 28 carrier, 30 membranes.

Claims (8)

An anaerobic treatment step of anaerobically treating the water to be treated containing at least one of the organic SS component and the oil and fat in an anaerobic fluidized bed reactor having a stirring device;
An aerobic treatment step of aerobically treating the anaerobic treated water obtained by the anaerobic treatment in a membrane separation activated sludge tank;
A water treatment method comprising: The water treatment method according to claim 1,
The SS concentration contained in the to-be-treated water is 400 mg / L or more, and the SS concentration is reduced to less than 400 mg / L in the anaerobic treatment step. The water treatment method according to claim 1 or 2,
A water treatment method, wherein a fat concentration contained in the water to be treated is 100 mg / L or more, and the fat concentration is reduced to less than 100 mg / L in the anaerobic treatment step. The water treatment method according to any one of claims 1 to 3,
In the anaerobic fluidized bed reactor, a gel-like carrier is used as a carrier. An anaerobic fluidized bed type reaction tank having a stirrer for anaerobically treating the water to be treated containing at least one of the organic SS component and oil and fat;
A membrane separation activated sludge tank for aerobic treatment of anaerobic treated water obtained by the anaerobic treatment;
A water treatment apparatus comprising: The water treatment device according to claim 5,
The SS concentration contained in the to-be-treated water is 400 mg / L or more, and the SS concentration is reduced to less than 400 mg / L by the anaerobic treatment. The water treatment device according to claim 5 or 6,
The water treatment apparatus characterized by the fat and oil density | concentration contained in the said to-be-processed water being 100 mg / L or more, and the fat and oil density | concentration being reduced to less than 100 mg / L by the said anaerobic treatment. The water treatment apparatus according to any one of claims 5 to 7,
In the anaerobic fluidized bed reactor, a gel-like carrier is used as a carrier.