JP2012206039A - Treatment apparatus of organic matter containing wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment apparatus of organic matter containing wastewater in which the film filterability of an aerobic biological treatment sludge is improved, film flux is maintained high, and chemical washing frequency is reduced when the aerobic biological treatment is performed after the organic matter containing waste water is performed by anaerobic biological treatment, and the aerobically biologically treated water is performed by a membrane separation treatment.SOLUTION: The treatment apparatus of organic matter containing wastewater includes: an anaerobic biological treatment tank 1 which performs the anaerobic biological treatment of the organic matter containing wastewater; an aerobic biological treatment tank 2 which performs the aerobic biological treatment of the anaerobically biologically treated water that flows out from the anaerobic biological treatment tank 1; and a membrane separator 5 which solid-liquid separates the aerobically biologically treated water of the aerobic biological treatment tank 2, and is characterized by providing a biological fixed bed 4 in the aerobic biological treatment tank 2.

Description

  The present invention relates to an organic matter-containing wastewater treatment apparatus for treating an organic matter-containing wastewater after anaerobic biological treatment and then subjecting the aerobic biological treatment water to membrane separation treatment, and in particular, to an aerobic treatment after an anaerobic biological treatment tank. In an organic matter-containing wastewater treatment system that uses a membrane-separated activated sludge-type aerobic biological treatment tank as the biological treatment tank, the membrane filterability of the aerobic biological treatment sludge is improved and the amount of permeated water (flux) is improved. The present invention relates to an organic matter-containing wastewater treatment device.

Conventionally, as a method for treating organic matter-containing wastewater, a method is known in which an organic matter-containing wastewater is subjected to anaerobic biological treatment, followed by aerobic biological treatment, and aerobic biologically treated water is solid-liquid separated (for example, Patent Document 1).
As a solid-liquid separation means for aerobic biologically treated water, a membrane separation activated sludge method is also known in which activated sludge is concentrated using a membrane separation device (for example, Patent Document 2).

  In the case of using a membrane separation device as a solid-liquid separation means for aerobic biologically treated water, anaerobic biological treatment produces less amount of metabolites that cause membrane sludge than aerobic biological treatment. When the anaerobic biological treatment is performed before the aerobic biological treatment, the membrane contamination is reduced and the chemical cleaning frequency of the membrane is reduced compared to the case where the raw water is directly subjected to the aerobic biological treatment and then the membrane separation treatment. There is an advantage that you can.

  In addition, as a method for treating organic matter-containing wastewater, a multistage activated sludge method using the predatory action of micro-animals such as protozoa and metazoans located at a high level of bacteria is also known and has already been put into practical use (for example, patents) Reference 3). In the multistage activated sludge method, the organic matter-containing wastewater is first treated with bacteria in the first biological treatment tank, the organic matter contained in the wastewater is oxidatively decomposed and converted into non-aggregating bacterial cells, and then the second biological treatment tank. By allowing the fixed micro-animal to prey and remove, excess sludge can be reduced and high-load operation can be performed.

JP 2007-175582 A JP 2009-297688 A JP 2006-51414 A

  As described above, when aerobic biological treatment water is solid-liquid separated with a membrane separation device, anaerobic biological treatment can be performed before the aerobic biological treatment to reduce membrane contamination by metabolites. Compared to aerobic biological treatment, the production of sticky substances is less and the ability to form flocs is weaker in aerobic biological treatment. Therefore, fine SS components with a diameter of less than 10 μm are treated with anaerobic biological treatment water, and aerobic biological treatment It becomes included in water. These fine SS components form a dense cake layer on the surface of the membrane in the membrane separation treatment, and easily increase the transmembrane pressure difference. For this reason, when anaerobic biological treatment water is subjected to aerobic biological treatment and solid-liquid separation is performed with a membrane separation device to obtain a clear treated water having no SS component, a high membrane flux cannot be obtained; There is a problem that chemical cleaning is required frequently.

  The present invention solves the above-mentioned conventional problems, anaerobic biological treatment of wastewater containing organic matter, followed by aerobic biological treatment, the membrane filterability of the aerobic biological treatment sludge in the membrane separation treatment It is an object of the present invention to provide an organic matter-containing wastewater treatment device that improves and maintains a high membrane flux and reduces the frequency of chemical cleaning.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have established a biological fixed bed in a membrane-separated activated sludge-type aerobic biological treatment tank, and thus, microanimals that prey on fine SS components, in particular, Providing scaffolds for filtered predatory micro-animals such as stag beetles with high removal capacity, preferentially increasing these micro-animals in an aerobic biological treatment tank, and produced by these micro-animals in anaerobic biological treatment It has been found that by efficiently feeding in fine SS, the membrane filterability of the aerobic biologically treated sludge is improved, and the membrane flux of the subsequent membrane separator is improved.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] An anaerobic biological treatment tank for anaerobically biologically treating organic matter-containing wastewater; an aerobic biological treatment tank for aerobically biologically treating anaerobic biological treated water flowing out of the anaerobic biological treatment tank; An organic matter-containing wastewater treatment apparatus having a membrane separation means for solid-liquid separation of aerobic biological treatment water in an aerobic biological treatment tank, wherein an organic matter is provided with a biological fixed bed in the aerobic biological treatment tank Wastewater treatment equipment.

[2] The organic matter-containing wastewater treatment apparatus according to [1], wherein the biological fixed bed has a volume of 1 to 30% with respect to a volume of the aerobic biological treatment tank.

[3] An apparatus for treating organic matter-containing wastewater according to [1] or [2], wherein the membrane separation means is a submerged membrane separator immersed in the aerobic biological treatment tank.

[4] In [3], the biological fixed bed is immersed in one half side of the aerobic biological treatment tank, and the submerged membrane separation device is immersed in the other half side, and is disposed below the submerged membrane separator. An organic matter-containing wastewater treatment apparatus, wherein aeration means is provided.

  According to the present invention, by providing a biological fixed bed in an aerobic biological treatment tank, a scaffold for microanimals that prey on fine SS components, in particular, filter predatory microanimals such as stag beetles that have a high removal ability, is provided. These micro animals can be preferentially increased in the aerobic biological treatment tank, and the fine SS generated by the anaerobic biological treatment can be efficiently consumed by these micro animals. The membrane filterability of the aerobic biological treatment sludge can be improved, the membrane flux of the subsequent membrane separation device can be maintained high, and the chemical cleaning frequency can be reduced to perform an efficient treatment.

It is a systematic diagram showing an embodiment of the present invention. 6 is a graph showing changes with time in transmembrane pressure difference in Example 1 and Comparative Example 1.

  Embodiments of an organic matter-containing wastewater treatment apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system diagram showing an example of an embodiment of the organic matter-containing wastewater treatment apparatus of the present invention. In FIG. 1, 1 is an anaerobic biological treatment tank, and 2 is an aerobic biological treatment tank. The anaerobic biological treatment tank 1 is filled with a carrier 3. A biological fixed bed 4 is immersed in one half side of the aerobic biological treatment tank 2 and a submerged membrane module 5 is immersed in the other half side. A diffuser tube (aeration means) is provided below the membrane module 5. 6 is provided. P ₁ and P ₂ are pumps, and PI is a pressure gauge.

  In FIG. 1, organic matter-containing wastewater (raw water) is introduced into the bottom of an anaerobic biological treatment tank 1 through a pipe 11 and is subjected to anaerobic biological treatment while flowing upward in the anaerobic biological treatment tank 1. The biologically treated water is introduced into the aerobic biological treatment tank 2 through the pipe 12. The aerobic biological treatment water in the aerobic biological treatment tank 2 is solid-liquid separated by the membrane module 5, and the membrane permeated water is taken out from the pipe 13 as treated water. Excess sludge is extracted from the pipe 14.

The treatment method of the anaerobic biological treatment tank 1 is not particularly limited, and may be a fixed bed type treatment tank in addition to a fluidized bed type filled with a fluid carrier 3 as shown in FIG. A sludge blanket of granulated sludge with high density and high sedimentation, and UASB (Upflow Anaerobic Sludge Blanket) method that performs high-load high-speed treatment by upward flow of raw water, EGSB (Expanded Granule Sludge Blanket), which uses raw reaction water at a high flow rate in a reaction tank that is higher than the UASB method, and develops sludge blankets at a high expansion rate for anaerobic treatment at higher loads. It may be a law.
Moreover, the 1 phase type which performs an acid production | generation reaction and a methane production | generation reaction in the same processing tank may be sufficient, and the 2 phase type which performs each reaction in another processing tank may be sufficient.

A fluidized bed type processing tank using a carrier, a fixed bed type processing tank, and a processing tank using granules such as UASB and EGSB are preferable because high load processing with a COD _Cr load of 5 kg / m ³ · d or more can be performed. .

  The aerobic biological treatment tank 2 shown in FIG. 1 is a submerged membrane separation activated sludge treatment tank in which the membrane module 5 is immersed in the tank. The membrane module is provided in the aerobic biological treatment tank 2 in this way. Not limited to this, an outside tank type membrane separation activated sludge method in which a membrane module is provided outside the aerobic biological treatment tank 2 may be adopted. In the case of the outside membrane separation activated sludge method, the membrane module is immersed in an aeration tank provided separately from the treatment tank 2 to obtain a membrane permeate, and the membrane concentrated water is circulated to the aerobic biological treatment tank 2. Good.

  Although it is possible to use a normal membrane module instead of a submerged membrane module, the power is relatively small and the shearing force is relatively low, so the size of the sludge is not reduced and the membrane is clogged. Therefore, it is preferable to employ a submerged membrane module.

  As the type of membrane, an MF (microfiltration) membrane or a UF (ultrafiltration) membrane excellent in solid-liquid separation of SS can be used, and there is no particular limitation on the type thereof, a flat membrane, a tubular membrane, Any of the hollow fiber membranes can be employed.

  In the aerobic biological treatment tank 2 of FIG. 1, the air diffuser 6 is provided below the membrane module 5. By providing the air diffuser 6 below the membrane module 5 in this way, the membrane surface of the membrane module 5 is provided. A part of the deposit is removed by the cleaning action of the aerated air by aeration to improve the membrane permeability.

  The biological fixed bed 4 provided in the aerobic biological treatment tank 2 serves as a scaffold for micro animals that prey on the fine SS components, in particular, filtration predatory micro animals such as stag beetles having high removal ability. It is only necessary to use a carrier fixed to the treatment tank such as a plastic corrugated sheet, net, honeycomb-shaped, fiber or rope with a ribbon, sponge plate, etc. that are generally used in the contact aeration method. A porous material such as a sponge is particularly preferable. In this case, micro-animals inhabit the porous holes, and these efficiently prey on the fine SS produced by the anaerobic biological treatment. The porous pore diameter is preferably about 200 to 1000 μm from the viewpoint of suspicion of minute animals.

  The volume of the biological fixed bed provided in the aerobic biological treatment tank 2 varies depending on the presence or absence of the membrane module in the treatment tank 2, but is preferably 1 to 30%, particularly preferably 5 to 10% with respect to the volume of the treatment tank 2. .

  If the volume of the biological fixed bed is too small, the micro-animal cannot be sufficiently grown. If the volume is too large, the cost increases and the stirring and mixing of the biological treatment tank tends to be insufficient. Here, the volume of the biological fixed bed is an apparent volume that does not take into account the porous holes, and the volume of the treatment tank refers to the volume excluding the volume of the membrane module immersed in the tank.

The biological fixed bed 4 provided in the aerobic biological treatment tank 2 is preferably provided in an area where the flow in the treatment tank 2 is small due to aeration, that is, an area where sludge wound up by aeration sinks as a downward flow. By doing so, it becomes easy to inhabit the micro animal which processes fine SS by a fixed bed.
For this reason, in the aerobic biological treatment tank 2 in FIG. 1, the biological fixed bed 4 is immersed in one half side of the treatment tank 2 and the membrane module 5 is immersed in the other half side. The air diffuser 6 is provided.

  The aerobic biological treatment tank 2 may be provided in multiple stages. For example, the first stage may be a denitrification tank and the latter stage may be a nitrification tank, and sludge may be circulated from the nitrification tank to the denitrification tank. In this case, the biological fixed bed is preferably provided in the nitrification tank, and the membrane module is preferably provided in the nitrification tank or another aeration tank (membrane immersion tank) for circulating the sludge in the nitrification tank.

As processing conditions of such an aerobic biological treatment tank 2, COD _Cr load 0.7-5 kg / m ³ · d, especially 1-2.5 kg / m ³ / d, BOD load 0.3-3 kg / m ³ · d, especially 0.5 to 2 kg / m ³ · d, MLSS concentration of 2,000 to 20,000 mg / L, especially 4,000 to 12,000 mg / L It is preferable from the point.

  The organic matter-containing wastewater to be treated by the organic matter-containing wastewater treatment apparatus of the present invention is not particularly limited as long as it is an organic matter-containing wastewater that is usually biologically treated. Examples include factory wastewater and food factory wastewater. For example, in the electronic component manufacturing process, a large amount of various organic wastewater is generated from the development process, peeling process, etching process, cleaning process, etc., and the wastewater can be collected and purified to a pure water level for reuse. These wastewaters are suitable as wastewater to be treated in the present invention, and high-purity water is obtained by further treating the treated water of the organic matter-containing wastewater treatment device of the present invention as necessary. Can do.

  Examples of such organic wastewater include organic wastewater containing isopropyl alcohol, ethyl alcohol, and the like, organic nitrogen such as monoethanolamine (MEA) and tetramethylammonium hydroxide (TMAH), and ammonia nitrogen. Organic waste water and organic waste water containing organic sulfur compounds such as dimethyl sulfoxide (DMSO) can be mentioned.

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

[Example 1]
Using the wastewater of the following water quality electronic component manufacturing factory as raw water, treatment was performed with the organic matter-containing wastewater treatment apparatus shown in FIG.

<Raw water quality>
COD _Cr : 1,500 to 3,000 mg / L (average 2,000 mg / L)
TN: 30 to 70 mg / L (average 50 mg / L)
TP: 3.0mg / L (added as a nutrient with Ca, Mg, K and other trace metals)

As the anaerobic biological treatment tank 1, a tank capacity of 10 L (φ16 cm × H60 cm cylindrical shape) was used, and the treatment was carried out by heating to a hydraulic retention time of 4.8 hr and a temperature of 35 ° C.
The anaerobic biological treatment tank 1 is filled with 4 L of a polypropylene cylindrical carrier (φ3 mm × 5 mm), and 500 mL of granule of a wastewater treatment facility in a beer factory is added as seed sludge, and after 2 months acclimatization, treated water is supplied. It introduced into the aerobic biological treatment tank 2.

  As the aerobic biological treatment tank 2, a tank having a tank capacity of 1.5 L is used. As the biological fixed bed 4, a sponge plate having a pore diameter of 500 μm and a thickness of 1 cm (apparent volume: 100 mL (aerobic biological treatment tank volume) 7%)) and fixed to a position where the sludge wound up by aeration from the diffuser tube 6 installed at the lower part of the membrane module 5 sinks.

  As the membrane module 5, a hollow fiber type MF membrane (“Microza MF Lab Module” manufactured by Asahi Kasei Chemicals Co., Ltd., manufactured by polyvinylidene fluoride, pore size 0.10 μm) was immersed and disposed above the diffuser tube 6.

The aerobic biological treatment tank 2 is activated sludge from the wastewater treatment facility of the electronic component manufacturing factory as seed sludge, and the membrane module 5 sucks with a cycle of 6 min suction filtration / 2 min stop and a filtration flux of 0.4 m / d. Then, the membrane was subjected to a membrane separation process, and excess sludge was drawn at 75 mL / d (SRT20d).
Moreover, when the transmembrane differential pressure rose to 30 kPa, the membrane module 5 was pulled up and chemical cleaning (immersion in an effective chlorine 0.3% NaClO + NaOH (adjusted to pH 12) solution for 6 hours) was performed.
The transition of the transmembrane pressure difference was measured from 2 weeks after the start of operation (2 weeks after the start of operation was set to 0 days of operation), and the change over time between the transmembrane differences is shown in FIG.

[Comparative Example 1]
In Example 1, it processed similarly except not having provided the biological fixed bed in the aerobic biological treatment tank 2, and the time-dependent change of transmembrane pressure difference was shown in FIG.

In both the example 1 and the comparative example 1, the anaerobic biological treatment tank 1 stably obtained a removal rate of around 90% throughout the test period with respect to a COD _Cr load of 10 kg / m ³ · d. The treated water COD _{Cr in the} treatment tank 2 was stably changed at 10 mg / L or less (Comparative Example 1: Average 5.4 mg / L, Example 1: Average 5.0 mg / L).
The rate of increase of the transmembrane pressure difference during the period when the operation was considered to be stable was Comparative Example 1: 1.3 kPa / d, Example 1: 0.54 kPa / d, and in Comparative Example 1, approximately once / 20 Whereas chemical cleaning was required on a daily basis, in Example 1, the chemical cleaning frequency could be reduced to about once / 50 days.
Furthermore, when the flux at the time of filtration was increased to 0.7 m / d, in Comparative Example 1, the rate of increase in the transmembrane pressure difference increased to 2.8 kPa / d, and chemical cleaning was performed at a frequency exceeding 1 time / 10 days. In contrast to the necessity, in Example 1, the increase rate of the transmembrane pressure difference was slight, and the cleaning frequency of about once / 50 days could be maintained.

  Moreover, when SS of anaerobic biological treatment water was analyzed, 60-100 mg / L of SS was contained in the anaerobic biological treatment water, and it always flowed into the aerobic biological treatment tank 2. When the particle size distribution of the SS component in the anaerobic biological treatment water and the aerobic biological treatment tank sludge was measured, the fine SS component having a particle size of less than 10 μm accounted for 40% in the anaerobic biological treatment water. Even in the aerobic biological treatment tank sludge, fine SS components having a particle diameter of less than 10 μm accounted for about 10%. In contrast, in the aerobic biological treatment tank sludge in Example 1, the fine SS component having a particle size of less than 10 μm is remarkably reduced to about 0.3%, and the fine SS component is decomposed in the aerobic biological treatment tank. It was thought that this led to an improvement in membrane filterability.

  As described above, according to the present invention, in the treatment combining the anaerobic biological treatment and the membrane separation activated sludge treatment, the membrane contamination due to the fine SS component generated by the anaerobic biological treatment is reduced, and the membrane washing frequency is reduced. It can be seen that the membrane flux can be increased and the operation can be performed.

DESCRIPTION OF SYMBOLS 1 Anaerobic biological treatment tank 2 Aerobic biological treatment tank 3 Carrier 4 Biological fixed bed 5 Membrane module 6 Aeration pipe

Claims (4)

An anaerobic biological treatment tank for anaerobically biologically treating organic wastewater,
An aerobic biological treatment tank for aerobically biologically treating anaerobic biological treatment water flowing out of the anaerobic biological treatment tank;
In a treatment apparatus for organic matter-containing wastewater having a membrane separation means for solid-liquid separation of aerobic biological treatment water in the aerobic biological treatment tank,
An organic matter-containing wastewater treatment apparatus, wherein a biological fixed bed is provided in the aerobic biological treatment tank.   In Claim 1, The volume of the said biological fixed bed is 1 to 30% with respect to the volume of the said aerobic biological treatment tank, The processing apparatus of the organic matter containing waste_water | drain characterized by the above-mentioned.   3. The organic matter-containing wastewater treatment apparatus according to claim 1 or 2, wherein the membrane separation means is a submerged membrane separation apparatus immersed in the aerobic biological treatment tank.   4. The biological fixed bed according to claim 3, wherein the biological fixed bed is immersed in one half side of the aerobic biological treatment tank, and the submerged membrane separation device is immersed in the other half side, and aeration means is provided below the submerged membrane separation device. An organic matter-containing wastewater treatment apparatus characterized by being provided.

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