JP2012205990A - Treatment apparatus of organic wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment apparatus of organic wastewater in which the organic wastewater decomposition reaction in an anaerobic treating tank can be efficiently performed in the treatment apparatus of organic wastewater in which the organic wastewater is performed with anaerobic treating, then is film-separated by an internal pressure type tubular membrane.SOLUTION: The treatment apparatus of organic wastewater includes an anaerobic treating tank 1 in which the organic wastewater is performed by anaerobic treating, and in the wastewater treatment apparatus, a treatment liquid in the anaerobic treating tank is performed by solid-liquid separation by an internal pressure type tubular membrane 3 at the outside of the anaerobic treating tank, wherein a microorganism immobilizing carriers 4, 5 exist in the anaerobic treating tank 1.

Description

  The present invention relates to a biological treatment apparatus that anaerobically treats organic wastewater (organic matter-containing wastewater) and solid-liquid separates this treatment liquid with a tank outer membrane, and is particularly suitable for treatment of electronic component manufacturing factory wastewater and the like. The present invention relates to an organic wastewater treatment apparatus.

  After anaerobic treatment of organic wastewater such as electronic component manufacturing factory wastewater, as an organic wastewater treatment device for membrane separation, Patent Document 1 anaerobically treats organic wastewater with an anaerobic group of methanogens And a method of membrane separation treatment using an RO membrane outside the tank is described.

  In this way, the membrane surface flow rate can be easily controlled and the contamination of the membrane surface can be prevented by adopting the outside type in which the membrane that separates the liquid content and solid content in the anaerobic treatment solution is provided outside the anaerobic treatment bath. Can do. In particular, in an internal pressure type tubular membrane, sludge and gas can be flowed at a high flow rate without being biased toward the membrane surface, and therefore a high flux can be obtained.

JP2009-148714

  Anaerobic treatment produces little mucilage and weak floc formation. In order to prevent contamination of the membrane surface, when a high flow rate is given by the internal pressure tubular membrane, the sludge flocs are refined by the high shearing force.

Some low-molecular-weight organic substances such as propionic acid, butyric acid, and isopropyl alcohol that are generated during the anaerobic decomposition of organic substances are produced by hydrogen / acetic acid producing bacteria (hydrogen / acetone producing bacteria in the case of isopropyl alcohol). Decomposition proceeds favorably because it is consumed quickly by the methanotrophic methane bacterium, the hydrogen partial pressure is maintained at 10 ⁻⁶ to 10 ⁻⁴ atm, and the symbiotic relationship between the two holds. In order for this symbiotic relationship to be established, it is necessary that both exist within several μm, and most reactions usually occur between cells fixed in a sludge floc having a particle size of several tens of μm. It seems that it is happening. If the sludge flocs become finer, the amount of cells maintained at an appropriate distance decreases, the symbiotic relationship is disrupted, and the processing does not proceed.

  The present invention is an organic wastewater treatment apparatus in which an organic wastewater is subjected to anaerobic treatment and then separated by an internal pressure tubular membrane outside the tank, and the organic matter decomposition reaction in the anaerobic treatment tank can be efficiently performed. An object of the present invention is to provide a wastewater treatment device.

  The organic wastewater treatment apparatus according to claim 1 is an anaerobic treatment tank for anaerobically treating organic wastewater, and a wastewater treatment apparatus for solid-liquid separation of the treatment liquid of the anaerobic treatment tank with an internal pressure tubular membrane outside the anaerobic treatment tank. The anaerobic treatment tank has a microorganism-immobilized carrier.

  The organic waste water treatment apparatus according to claim 2 is characterized in that, in claim 1, the surface flow velocity of the treatment liquid in the internal pressure tubular membrane is 0.5 m / sec or more.

  According to a third aspect of the present invention, there is provided an organic wastewater treatment apparatus according to the first or second aspect, wherein the organic wastewater contains isopropyl alcohol as a main component.

  In the organic wastewater treatment apparatus of the present invention, after the organic wastewater is subjected to anaerobic treatment, the microorganism-immobilized carrier exists in the anaerobic treatment tank in which the membrane is separated by an internal pressure tubular membrane outside the tank. Let As a result, the decomposition of the organic matter involving the symbiotic relationship between the cells surrounding hydrogen, such as propionic acid, butyric acid and isopropyl alcohol, which are generated in the process of anaerobic decomposition of the organic matter, is stably performed by the cells attached to the carrier. In addition, the solid-liquid separation process is performed with a high flux by the internal pressure tubular membrane.

It is a flowchart of the processing device of organic drainage concerning an embodiment. It is a flowchart of the processing device of organic drainage concerning an embodiment. It is a graph which shows an experimental result. It is a graph which shows an experimental result.

  Hereinafter, the present invention will be described in more detail.

  In the present invention, the organic waste water is subjected to anaerobic treatment in an anaerobic treatment tank having a microorganism-immobilized carrier, and the anaerobic treated water is subjected to membrane separation using an internal pressure tubular membrane (internal pressure tubular membrane) outside the tank.

  1 and 2 each show an example of the organic wastewater treatment apparatus of the present invention. Raw water is introduced into the anaerobic treatment tank 1 and subjected to anaerobic treatment. The liquid in the tank is taken out through the screen 1b and supplied to the internal pressure tubular membrane 3 outside the tank by the pump 2 for membrane separation. The membrane permeated water is taken out as treated water, and the concentrated water is returned to the anaerobic treatment tank 1. In FIG. 1, an anaerobic treatment tank 1 is filled with a fluid carrier 4 as a microorganism-immobilized carrier. In FIG. 2, a fixed bed type microorganism immobilization carrier 5 is installed in the anaerobic treatment tank 1. The anaerobic treatment tank 1 is provided with a stirrer 1a.

  Biogas such as methane gas generated in the anaerobic treatment tank 1 is extracted via the gas extraction line 6. In this embodiment, a part of the biogas is internally tubular via the branch line 7 and the blower 8. Supplied to the membrane 3. Thus, by circulating biogas through the internal pressure tubular membrane 3, the membrane surface is washed and membrane filtration efficiency is improved. A non-oxidizing gas such as nitrogen may be supplied instead of or together with the biogas.

  As organic wastewater, in addition to electronic component manufacturing factory wastewater, chemical factory wastewater, pharmaceutical factory wastewater, food / beverage factory wastewater, sewage, etc., the TOC is 100 to 10,000 mg / L, particularly about 300 to 3,000 mg / L. Those are preferred. The main component of the organic matter in the organic waste water includes isopropyl alcohol, but also includes diethylene glycol monobutyl ether and tetramethylammonium hydroxide.

The anaerobic treatment tank preferably has a COD _cr load of 2 to 50 kg / m ₃ · d, particularly 5 to 20 kg / m ³ · d. The membrane sludge concentration (also the sludge concentration of the liquid supplied to the internal pressure tubular membrane 3) is about 4,000 to 30,000 mg SS / L, particularly about 6,000 to 12,000 mg / L. It is preferable in terms of good filterability.

  The material, shape, size, etc. of the microorganism-immobilized carrier in the anaerobic treatment tank are not particularly limited. Examples of the flow type carrier include granular, spherical, columnar, and cylindrical carriers of about 1 to 50 mm, and examples of the stationary carrier include sponge, string, and net shapes. It is not limited. The amount of the carrier present is preferably about 10 to 70%, particularly about 20 to 40% with respect to the anaerobic treatment tank capacity.

  The internal pressure tubular membrane is one in which a liquid to be treated is circulated inside the tubular membrane, and the permeate is permeated to the outer peripheral surface side of the tube to be taken out. The diameter of one internal pressure tubular membrane module is preferably 3 mm to 3 cm, and the pore diameter is preferably 0.01 to 1 μm. It is preferable to pass the treatment liquid in the anaerobic treatment tank through the internal pressure tubular membrane at 0.5 m / sec or more, for example, 0.5 to 2 mm / sec. As described above, the membrane filterability can be improved by aerating a gas not containing oxygen such as a gas mainly composed of methane generated by anaerobic treatment or nitrogen gas together with the treatment liquid.

  In the organic wastewater treatment apparatus of the present invention configured as described above, in the organic wastewater treatment apparatus in which the organic wastewater is subjected to anaerobic treatment and then separated by the internal pressure tubular membrane 3 outside the tank, the anaerobic treatment tank 1 Since the microorganism-immobilized carrier 4 or 5 is present in the inside, the decomposition of the organic matter involving the symbiotic relationship between the cells surrounding hydrogen such as propionic acid, butyric acid and isopropyl alcohol generated in the process of anaerobic decomposition of the organic matter It is carried out stably by the cells attached to the carrier.

[Example 1]
In accordance with the flow shown in FIG. 1, raw water having the following water quality was treated under the following conditions.
<Raw water>
Wastewater from electronic component manufacturing plant 1.5m ³ / d
TOC 300-700 mg / L (average 500 mg / L), TN 30-70 mg / L (average 50 mg / L), TP 3.0 mg / L (added as a nutrient with other inorganic salts)
Composition of organic matter
Isopropyl alcohol (IPA) 200-400 mg / L
Diethylene glycol monobutyl ether (BDG) 200-400mg / L
Tetramethylammonium hydroxide (TMAH) 200-400 mg / L

<Anaerobic treatment tank>
Capacity 500L (hydraulic residence time 8hr)
Water temperature 35 ℃
The sewage sludge was used as seed sludge for 6 months. The sludge was drawn out so as to maintain MLSS 12,000 mg / L in the tank.

A PVA sponge carrier (30 mm square) was added at a volume ratio of 30%. A 5 mm wide screen was installed in the liquid outflow part to prevent the carrier from flowing out of the tank. In addition, 4 Nm ³ / h of the biogas generated from the anaerobic treatment tank was supplied to the internal pressure tubular membrane.

<Internal pressure tubular membrane>
Norit's airlift UF membrane module 33PE (pore size 0.03 μm, membrane area 5.1 m ² )
The anaerobic treatment solution was passed at 4 m ³ / hr so that the treatment solution surface flow velocity in the internal pressure tubular membrane was 0.5 m / sec, the permeate was taken out, and the concentrated solution was returned to the anaerobic treatment tank.
In a cycle of 3 min filtration and 10 sec backwashing, treated water corresponding to the amount of raw water was sucked out from the secondary side of the membrane. At the time of backwashing, treated water was passed from the secondary side at 7.2 m ³ / hr.

The operation results are shown in FIGS. FIG. 3 shows the change over time of the COD _Cr load (kg / m ³ · d) of the anaerobic treatment tank. FIG. 4 shows changes with time in the TOC removal rate.

[Comparative Example 1]
The same raw water was operated for the same period as in Example 1 except that the anaerobic treatment tank was not filled with the microorganism-immobilized carrier. The results are shown in FIGS.

As shown in FIGS. 3 and 4, with respect to the COD _cr load that fluctuated at 4 to 7.5 kg / m ³ · d for 3 months, the removal rate of 96% or more was stably maintained in Example 1, and the treated water TOC was 30 mg. Whereas / L or less was satisfied, in Comparative Example 1, the removal rate remained at 60 to 80%, particularly when the load increased rapidly, the quality of the treated water deteriorated, and the effect continued for a long time. Analysis of the residual organic matter in the treated water of Comparative Example 1 revealed that most of it was butyric acid, which was thought to have been generated during the decomposition process of IPA and BDG, and the hydrogen partial pressure increased when the load increased, It is thought that degradation was inhibited.

  As described above, according to the present invention, with respect to organic components whose decomposition progresses due to the symbiosis between bacterial cells surrounding hydrogen, the decomposition proceeds stably, and solid-liquid separation and treatment at high flux by an internal pressure tubular membrane It is possible to achieve both stabilization.

1 Anaerobic Treatment Tank 3 Internal Pressure Tubular Membrane 4, 5 Microorganism Immobilization Support

Claims (3)

  An anaerobic treatment tank for anaerobically treating organic wastewater, and a wastewater treatment apparatus for solid-liquid separation of the treatment liquid in the anaerobic treatment tank with an internal pressure tubular membrane outside the anaerobic treatment tank, the microorganism-immobilized carrier is present in the anaerobic treatment tank. Organic wastewater treatment equipment characterized by that.   2. The organic wastewater treatment apparatus according to claim 1, wherein the surface flow velocity of the treatment liquid in the internal pressure tubular membrane is 0.5 m / sec or more.   3. The organic waste water treatment apparatus according to claim 1, wherein the organic waste water contains isopropyl alcohol as a main component.

Images