JP2013056321A - Anaerobic biological treatment method and anaerobic biological treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anaerobic biological treatment method and an anaerobic biological treatment apparatus capable of stable treatment with high load in an anaerobic biological treatment of wastewater containing organic matters with a carbon number of 6 or less.SOLUTION: The anaerobic biological treatment apparatus 1 is used which includes a reaction tank 16 which ferments the wastewater containing the organic matters having the carbon number of 6 or less with methane under an anaerobic condition, and a membrane separator 26 that separates a treatment liquid obtained by the reaction tank 16 into sludge and treated water by a filter membrane, wherein a biological sludge concentration in the reaction tank 16 is adjusted to be within a range of 15,000-35,000 mg/L.

Description

  The present invention relates to a biological treatment method and biological treatment apparatus for biologically treating wastewater containing organic matter having 6 or less carbon atoms under anaerobic conditions.

  Conventionally, carbon number of 6 or less, specifically methanol, tetramethylammonium hydroxide (hereinafter sometimes referred to as TMAH), ethanol, acetaldehyde, acetic acid, etc. discharged from electronic industrial factories, pulp manufacturing factories, and chemical factories In the case of anaerobic treatment of wastewater containing organic substances as a main component under high load, UASB (Upflow Anaerobic Sludge Blanket), EGSB (Expanded Granular Sludge Blanket), etc. using granule sludge are applied.

  In normal anaerobic treatment, the cross-linking effect of anaerobic hydrolyzing bacteria that decompose high molecular carbohydrates, proteins, and lipids into low molecules and biopolymers produced by acid-producing bacteria that produce organic acids, etc. It is thought to play an important role in maintenance. Furthermore, the genus Methanosaeta, which is a filamentous methanogenic bacterium, is said to be a skeleton for granulation, and is an important entity for granule formation.

  However, when decomposing organic substances having a small number of carbon atoms, there are few anaerobic hydrolyzing bacteria and acid-producing bacteria, and methanogenic bacteria are the main biota. Further, in methanol, TMAH, and the like, the genus Methanosalucina and Methanobacterium, which are non-filamentous methanogens, are more dominant than the genus Methanosaeta, which is a filamentous methanogen, and the granular sludge tends to become finer and collapse. If the granule sludge becomes finer and collapses, the sludge in the reaction tank flows out and the treatment becomes unstable.

  Conventional examples of these measures include, for example, a method of adding a polymer flocculant, a method of adding nitrous acid and nitric acid, a method of adding acetic acid, a method of adding starch and glucose, and adding molasses and alcohol And the like have been proposed (see, for example, Patent Documents 1 to 6).

  In addition, a method has been proposed in which wastewater containing dimethyl sulfoxide, monoethanolamine, and TMAH discharged from an electronics industry factory is subjected to biological treatment by anaerobic methane fermentation and then subjected to solid-liquid separation treatment using a filtration membrane (for example, And Patent Documents 7 and 8).

Japanese Patent No. 4193310 JP 2008-279383 A Japanese Patent No. 2563004 JP 2008-279385 A JP 2010-274207 A JP 2009-255067 A JP 2010-17614 A JP 2010-17615 A

  However, in the methods described in Patent Documents 1 to 6, since it is necessary to add a polymer flocculant, nitric acid, organic matter, and the like from the outside, appropriate management of these drugs is necessary. In addition, in the methods described in Patent Documents 7 and 8, although a chemical is not added, low load treatment is performed in a low-concentration drainage system.

  Accordingly, an object of the present invention is to provide an anaerobic biological treatment method and an anaerobic biological treatment apparatus that can stably perform treatment at high load in anaerobic biological treatment of wastewater containing organic matter having 6 or less carbon atoms. There is.

  The anaerobic biological treatment method of the present invention includes a biological treatment step of subjecting wastewater containing an organic substance having 6 or less carbon atoms to methane fermentation under anaerobic conditions, and treating liquid obtained in the biological treatment step with sludge and treated water using a filtration membrane. And the biological sludge concentration in the biological treatment step is adjusted to a range of 15000 to 35000 mg / L.

  In the anaerobic biological treatment method, the organic substance is preferably at least one of tetramethylammonium hydroxide and methanol.

  In the anaerobic biological treatment method, it is preferable to adjust the waste water so that the organic matter is single and contains 90% by weight or more of the total organic matter in the waste water.

In the anaerobic biological treatment method, the biological treatment step is effective when the biological treatment is performed with a CODcr load of 10 kg / m ³ / d or more or a TMAH load of 5 kg / m ³ / d.

  Moreover, the anaerobic biological treatment apparatus of this invention is a reaction tank which carries out methane fermentation of the waste_water | drain containing C6 or less organic substance under anaerobic condition, and the process liquid obtained in the said reaction tank is made into sludge and treated water with a filtration membrane. And the biological sludge concentration in the reaction tank is adjusted to a range of 15000 to 35000 mg / L.

  In the anaerobic biological treatment apparatus, the organic substance is preferably at least one of tetramethylammonium hydroxide and methanol.

  Moreover, in the anaerobic biological treatment apparatus, the membrane separation unit is preferably provided outside the reaction tank.

  Moreover, in the anaerobic biological treatment apparatus, it is preferable that the waste water has means for adjusting the organic matter so that the organic matter is contained in a single amount and is 90% by weight or more of the total organic matter in the waste water.

In the anaerobic biological treatment apparatus, the reaction vessel is effective when biological treatment is performed at a CODcr load of 10 kg / m ³ / d or more or a TMAH load of 5 kg / m ³ / d.

  ADVANTAGE OF THE INVENTION According to this invention, in the anaerobic biological treatment of the waste_water | drain containing C6 or less organic substance, it can process stably with high load.

It is a schematic diagram which shows an example of a structure of the anaerobic biological treatment apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of a structure of the anaerobic biological treatment apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of a structure of the anaerobic biological treatment apparatus which concerns on this embodiment. It is the TMAH density | concentration and TMAH load in the treated water obtained by Example 1. FIG. It is a daily change of the suction pressure of the filtration membrane used in Example 1. FIG. It is a TMAH density | concentration and TMAH load in the treated water obtained by the comparative example 1. It is the methanol density | concentration and CODcr load in the treated water obtained by Example 2. FIG. It is a daily change of the suction pressure of the filtration membrane used in Example 2. FIG. It is the figure which put together the relationship between the sludge density | concentration of the anaerobic sludge of Example 3, and a viscosity.

  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.

  FIG. 1 is a schematic diagram illustrating an example of the configuration of the anaerobic biological treatment apparatus according to the present embodiment. As shown in FIG. 1, the anaerobic biological treatment apparatus 1 includes a raw water first line 10, a raw water tank 12, a raw water second line 14, a reaction tank 16, a treatment liquid discharge line 19, a treated water discharge line 20, and a gas discharge line. 22, a concentrated water return line 24, a membrane separation device 26, a nutrient supply device, and a pH adjuster supply device. The nutrient supply device of the present embodiment includes a nutrient storage tank 30 and a nutrient supply line 32. The pH adjuster supply device of this embodiment includes a pH adjuster storage tank 34 and a pH adjuster supply line 36. However, the configuration of each supply device is not limited to the above configuration as long as the solution can be supplied to the waste water. For example, in order to freely adjust the flow rate of the solution, a pump is connected to each supply line. It is preferable to install. A stirring device 38 is provided in the raw water tank 12, and it is preferable to make the concentration uniform by the stirring device 38 or the like.

  A raw water first line 10 is connected to a raw water inlet (not shown) of the raw water tank 12. A nutrient solution discharge port (not shown) of the nutrient solution storage tank 30 and a nutrient solution supply port (not shown) of the raw water tank 12 are connected by a nutrient solution supply line 32, and a pH adjuster discharge port (not shown) of the pH raw water tank 12. The pH adjuster supply port (not shown) of the raw water tank 12 is connected by a pH adjuster supply line 36. The raw water discharge port (not shown) of the raw water tank 12 and the reaction tank 16 are connected by a raw water second line 14. In addition, it is preferable that the connection position of the raw | natural water 2nd line 14 by the side of the reaction tank 16 is the lower part of the reaction tank 16. FIG.

  A gas-solid-liquid separator (hereinafter sometimes referred to as GSS) is provided in the reaction tank 16. The gas-solid-liquid separator includes partition plates 40a and 40b that are inclined in opposite directions, and a solid-liquid separator 42 is formed inside the upper part thereof. The lower ends of the partition plates 40a and 40b are isolated, and a communication passage 44 is formed. One lower end portion of the partition plates 40a and 40b covers the lower side of the other lower end portion, and the rising gas is connected to the communication passage. In this structure, the solid-liquid separation unit 42 is prevented from entering from 44. The solid-liquid separation unit 42 is provided with an overflow type treatment liquid extraction unit 46, and the treatment water discharge line 20 is connected to a treatment water discharge port (not shown) of the treatment water extraction unit 46. A gas discharge line 22 is connected to the top of the reaction tank 16.

  Since the reaction tank 16 may be anything that can biologically treat wastewater containing organic matter under anaerobic conditions, the reaction tank 16 is a mixed reaction tank in which GSS is installed in the tank like the reaction tank 16 in FIG. It is not limited, A mixed reaction tank etc. which does not install GSS in a tank may be sufficient.

  Prior to biological treatment under anaerobic conditions, seed sludge used for biological treatment is preferably introduced into the reaction tank 16. The seed sludge is not particularly limited, but for example, anaerobic sludge, granule, or digested sludge from a sewage treatment plant used in food factories, beverage factories, paper factories, chemical factories, livestock wastewater treatment, etc. Etc.

  A processing liquid discharge line 19 is connected between the processing liquid discharge port (not shown) of the reaction tank 16 and the processing liquid supply port (not shown) of the membrane separation device 26. A treated water discharge line 20 is connected to a treated water discharge port (not shown) of the membrane separation device. The concentrated water discharge port (not shown) of the membrane separator 26 and the concentrated water supply port (not shown) of the raw water tank 12 are connected by a concentrated water return line 24.

  A filtration membrane is provided in the membrane separator 26. The filtration membrane is not particularly limited as long as it can separate sludge and the like in the treatment liquid mainly treated by the reaction tank 16, but for example, an ultrafiltration membrane (UF membrane), Examples thereof include a microfiltration membrane (MF membrane). The module formation of the membrane separation device 26 is not particularly limited, and for example, a module format in which hollow fiber membranes are bundled, a format in which flat membranes are unitized, or the like is adopted. In the present embodiment, the membrane separation device 26 is an outside tank type provided outside the reaction tank 16, but is not limited to this, and an inside tank type provided in the tank as will be described later. It may be. However, an outside tank type membrane separation device is preferable in terms of operation management such that the filtration membrane of the membrane separation device 26 can be washed or replaced separately from the reaction vessel 16. In the case of an outside tank type membrane separation device, for example, a cross flow type membrane surface flow velocity is set in a range of 0.1 to 3 m / s in order to prevent clogging of a filtration membrane due to biological sludge described later. It is preferable.

  Operation | movement of the anaerobic biological treatment apparatus 1 of this embodiment is demonstrated.

  First, wastewater containing an organic substance having 6 or less carbon atoms is supplied from the raw water first line 10 to the raw water tank 12. Then, the waste water is introduced into the reaction tank 16 from the raw water second line 14. In the reaction tank 16, organic substances having 6 or less carbon atoms are subjected to methane fermentation treatment with biological sludge under anaerobic conditions, and decomposed into methane, carbonate ions, and the like. As described above, when wastewater containing an organic substance having 6 or less carbon atoms is biologically treated under anaerobic conditions, biological sludge particles in the reaction tank are refined (particularly noticeably in granular sludge). Biological sludge flows out together with the treated water, and clogging of the filtration membrane used in the subsequent membrane separation device is likely to occur. Therefore, conventionally, wastewater containing organic substances with 6 or less carbon atoms has been maintained by anaerobic MBR (Membrane Bioreactor) that combines biological treatment under anaerobic conditions and solid-liquid separation treatment (membrane treatment) using a filtration membrane. Thus, it has been difficult to realize stable processing and high load processing equivalent to processing using granules such as UASB (Upflow Analytic Slack Blanket) and EGSB (Expanded Granular Sludge Blanket). However, as a result of intensive studies, the inventors of the present invention treated the wastewater containing organic matter having 6 or less carbon atoms with anaerobic biological treatment under appropriate operating conditions, thereby maintaining an excessive viscosity of microbial sludge while maintaining a high concentration of sludge. It has been found that the rise is suppressed and the biological sludge is less likely to clog the pores of the subsequent filtration membrane. As a result, stable processing can be realized even with a high load.

  In the present embodiment, a single organic substance having 6 or less carbon atoms is particularly effective when biologically treating wastewater containing 90% by weight or more of the entire organic substance under anaerobic conditions.

  Therefore, for example, when TMAH, methanol, and other organic substances having 7 or more carbon atoms are contained in the waste water discharged from the electronic industry factory, pulp manufacturing factory, chemical factory, etc., the waste water is used as the reaction tank 16. Before being put into the wastewater (substantially before being put into the raw water first line 10), TMAH is separated into wastewater containing 90% by weight or more of the whole organic matter, and wastewater containing 90% by weight or more of the whole organic matter. Process it. Then, for example, wastewater containing 90% by weight or more of TMAH in the whole organic matter is put into the reaction tank 16 to perform biological treatment. The fractionation treatment is not particularly limited as long as the content of a single organic substance having 6 or less carbon atoms satisfies the above range.

  Examples of the organic matter having 6 or less carbon atoms contained in the waste water of this embodiment include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethylethylammonium hydroxide, dimethyldiethylammonium hydroxide, and isopropyl alcohol (IPA). , Methanol, monoethanolamine, acetic acid, propylene glycol monomethyl ether (PGME), cyclohexanone, dimethyl sulfoxide (DMSO), propylene glycol methyl ether acetate (PGMEA) and the like. The present embodiment is particularly suitable for the treatment of tetramethylammonium hydroxide (TMAH) and methanol discharged from a semiconductor manufacturing factory or the like.

  In addition, if the wastewater supplied to the reaction tank 16 contains a single organic substance having 6 or less carbon atoms, such as TMAH, in an amount of 90% by weight or more of the whole organic substance, other organic substances having 6 or less carbon atoms or Further, it may contain an organic substance having 7 or more carbon atoms. Examples of the organic substance having 7 or more carbon atoms include, for example, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, trimethyl (2-hydroxyethyl) ammonium hydroxide (that is, choline) and the like.

  As described above, in the reaction tank 16, organic matter in the wastewater is decomposed into methane, carbonate ions, and the like by biological treatment under anaerobic conditions. Then, the biologically processed liquid (including biological sludge and the like) enters the solid-liquid separation unit 42 from the communication path 44, and the solid-liquid separated processing liquid overflows and flows to the processing liquid extraction unit 46, and the processing liquid discharge line 19 is taken out. A gas such as methane generated in the reaction tank 16 is blocked by the partition plates 40 a and 40 b and does not flow into the solid-liquid separation unit 42, but rises in the reaction tank 16 and is taken out from the gas discharge line 22.

  The treatment liquid flowing through the treatment liquid discharge line 19 flows into the membrane separation device 26 and is separated into sludge and treated water. And treated water is discharged | emitted from the membrane separator 26, passes through the treated water discharge line 20, and is discharged | emitted out of the system. Concentrated water (including sludge) in the membrane separator 26 is supplied to the raw water tank 12 from the concentrated water return line 24. Thereby, since concentrated water is supplied from the raw water tank 12 to the reaction tank 16, it is possible to easily prevent a decrease in the sludge concentration in the reaction tank 16.

In the present embodiment, digested sludge, granules and the like are introduced into the reaction tank 16, and concentrated water (including biological sludge) in the membrane separation device 26 is supplied to the reaction tank 16. The sludge concentration is adjusted to the range of 15000 to 35000 mg / L. In addition, since sludge increases due to biological treatment, when the sludge concentration exceeds 35000 mg / L, a part of the sludge is obtained from at least one of the reaction tank 16 and the line for supplying the concentrated water of the membrane separator to the reaction tank 16. And the sludge concentration in the reaction tank 16 is adjusted to a range of 15000 to 35000 mg / L. When the sludge concentration in the reaction tank 16 is less than 15000 mg / L, biological treatment may not be performed with a high load. Here, “high load treatment” refers to performing an anaerobic biological treatment with a CODcr load of 10 kg / m ³ / d or more or a TMAH load of 5 kg / m ³ / d or more, for example. Moreover, when the sludge density | concentration in the reaction tank 16 exceeds 35000 mg / L, the viscosity of biological sludge will raise and the clogging of the filtration membrane of a back | latter stage will be caused, and as a result, the process with a high load may be impossible.

  Below, an example of the other conditions of the anaerobic biological treatment of this embodiment is demonstrated.

  In the present embodiment, the concentration of a single organic substance having 6 or less carbon atoms in the wastewater when flowing into the reaction tank 16 (when biologically treating) is preferably 10000 mg / L or less, and is 2000 mg / L or more to 5000 mg / L. It is preferable to set it as the range below L. If the concentration of a single organic substance having 6 or less carbon atoms in the waste water when flowing into the reaction tank 16 exceeds 10,000 mg / L, the decomposition reaction rate of the organic substance may be slow during biological treatment. In this embodiment, when the concentration of a single organic substance having 6 or less carbon atoms in the wastewater supplied to the raw water tank 12 exceeds 10,000 mg / L, a part of the treated water after biological treatment is returned to the concentrated water. It is desirable to supply the raw water tank 12 from the line 24 and dilute to a concentration of 10000 mg / L or less.

  In the present embodiment, for example, a sensor that detects the concentration of organic substances in the treated water after biological treatment may be installed in the treated water discharge line 20 or the like. And based on the detected organic substance density | concentration, the single organic substance density | concentration of C6 or less at the time of flowing in into the reaction tank 16 is estimated, and based on the estimated value, a single organic substance density | concentration of C6 or less is obtained. It is preferable to determine the supply amount of the treated water so as to be in the above range. Further, for example, a sensor for detecting the organic substance concentration may be installed in the raw water tank 12 or the raw water first line 10 or the like. Moreover, instead of the biologically treated treated water, for example, industrial water, effluent water, or distilled water (condensed water) obtained from distillation of ammonia waste liquid, IPA waste liquid or the like when there is equipment in the factory. Dilution water may be diluted using dilution water. Distilled water is preferable in that the water temperature is as high as 40 ° C., so that the reaction tank 16 can be heated and the decomposition reaction of organic matter can be promoted.

  In this embodiment, when biologically treating organic matter-containing wastewater, the pH of the wastewater is preferably in the range of 6.5 to 9.0, and more preferably in the range of 7.0 to 8.0. The pH adjustment of the waste water is performed by supplying the pH adjuster to the raw water tank 12 from the pH adjuster supply line 36, for example. If the pH of the organic matter-containing wastewater is outside the above range, the decomposition reaction rate of organic matter due to biological treatment may decrease. Conventionally, in the case of anaerobic biological treatment of alkylammonium salts such as TMAH, a weak acidity of pH 6.5 to 7 has been preferred to suppress ammonia inhibition, but alkylammonium salts such as TMAH are preferred. As for the treatment, the treatment performance is best on the weak alkali side having a pH of 7-8.

  The pH adjuster used in the present embodiment is not particularly limited, such as an acid agent such as hydrochloric acid or an alkali agent such as sodium hydroxide. Further, the pH adjusting agent may be, for example, sodium bicarbonate having a buffering action, a phosphate buffer or the like.

  In this embodiment, in order to maintain the decomposition | disassembly activity of anaerobic biological sludge favorably, it is preferable to supply a nutrient to the raw | natural water tank 12 from the nutrient supply line 32, for example. Although it does not restrict | limit especially as a nutrient, For example, a carbon source, a nitrogen source, other inorganic salts etc. are mentioned.

  In the present embodiment, when biologically treating organic matter-containing wastewater, it is preferable to adjust the temperature of the water in the reaction tank 16 to be 20 ° C. or higher, and to adjust the temperature to be in the range of 28 to 35 ° C. More preferred. The decomposition of the organic substance by the anaerobic biological treatment is possible even at a temperature lower than 20 ° C. However, if the temperature is lower than 20 ° C., the decomposition reaction rate is lowered. The temperature adjusting method is not particularly limited. For example, the water temperature in the reaction tank 16 may be adjusted by supplying steam to the raw water tank 12, or a heater is installed in the reaction tank 16. The water temperature in the reaction tank 16 may be adjusted by the heat of the heater. Further, for example, the water temperature in the reaction tank 16 may be adjusted by supplying warmed dilution water. In addition, for example, methane gas is generated by decomposition of an organic substance having 6 or less carbon atoms, but after performing a desulfurization process in the same manner as a normal anaerobic process, it is recovered as thermal energy with a methane gas boiler, and the thermal energy is supplied to the reaction tank 16. The water temperature may be adjusted.

  FIG. 2 is a schematic diagram illustrating another example of the configuration of the anaerobic biological treatment apparatus according to the present embodiment. In the anaerobic biological treatment apparatus 2 shown in FIG. 2, the same components as those in the anaerobic biological treatment apparatus 1 shown in FIG. In the anaerobic biological treatment apparatus 2 shown in FIG. 2, a membrane separation device 27 is provided in the reaction tank 16, and a treated water discharge line 20 is connected to a treated water discharge port (not shown) of the membrane separation device 27. Yes. In the present embodiment, no solid-liquid separation device is installed in the reaction tank 16.

  Also in this embodiment, as described above, wastewater containing organic matter having 6 or less carbon atoms is supplied into the reaction tank 16 and biologically treated under anaerobic conditions in which the sludge concentration is adjusted to 15000 to 30000 mg / L. The As a result, the refinement of the biological sludge in the reaction tank 16 is alleviated and the increase in the viscosity of the biological sludge is also suppressed. As a result, even when the membrane separation device 27 is installed in the reaction tank 16, clogging of the filtration membrane of the membrane separation device 27 can be suppressed, so that processing with a high load is possible.

  The separation membrane device 27 installed in the reaction tank 16 is preferably a hollow fiber membrane module in which a large number of hollow fiber membranes are bundled and accommodated so as to extend in parallel in a cylindrical case. Note that both ends of the bundled hollow fiber membranes are bonded and fixed to each other using an adhesive resin in a cylindrical case.

  FIG. 3 is a schematic diagram showing another example of the configuration of the anaerobic biological treatment apparatus according to the present embodiment. In the anaerobic biological treatment apparatus 3 shown in FIG. 3, the same code | symbol is attached | subjected about the structure similar to the anaerobic biological treatment apparatus 1 shown in FIG. The anaerobic biological treatment apparatus 3 of the present embodiment is provided with a plurality of reaction vessels. Specifically, a first reaction tank 16 and a second reaction tank 17 are provided. A membrane separation device 27 is installed in the second reaction tank 17. In addition, as shown in FIG. 3, a treatment liquid discharge line 19 is provided between a treated water discharge port (not shown) of the first reaction tank 16 and a treated water supply port (not shown) of the second reaction tank 17. It is connected. A concentrated water return line 24 is connected between the concentrated water discharge port (not shown) of the membrane separator 27 and the concentrated water supply port (not shown) of the first reaction tank 16. Further, a treated water discharge line 20 is connected to a treated water discharge port (not shown) of the membrane separation device 27.

  In the anaerobic biological treatment apparatus shown in FIG. 3, wastewater containing a single organic substance having 6 or less carbon atoms is supplied into the first reaction tank 16 and the sludge concentration is adjusted to 15000 to 3000 mg / L. Biologically treated under anaerobic conditions. Further, the waste water in the first reaction tank 16 and the treatment liquid biologically treated in the first reaction tank 16 are supplied from the treatment liquid discharge line 19 into the second reaction tank 17. In the second reaction tank 17, wastewater containing organic matter is biologically treated under anaerobic conditions, and biological sludge in the treatment liquid is removed by the membrane separation device 27 in the second reaction tank 17. A part of the concentrated water that has been subjected to the membrane separation treatment is returned from the concentrated water return line 24 into the first reaction tank 16 so that, for example, the sludge concentration in the first reaction tank 16 is adjusted. The treated water that has been solid-liquid separated by the membrane separator 27 is discharged from the treated water discharge line 20 to the outside of the system.

  Also in this embodiment, as described above, wastewater containing a single organic substance having 6 or less carbon atoms is supplied into the first reaction tank 16 and the second reaction tank 17 and is biologically treated under anaerobic conditions. . As a result, the refinement of the biological sludge in the first reaction tank 16 and the second reaction tank 17 is alleviated, and the increase in the viscosity of the biological sludge is suppressed. As a result, even when the membrane separation device 27 is installed in the second reaction tank 17, clogging of the filtration membrane of the membrane separation device 27 can be suppressed, so that processing with a high load is possible.

  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
The test of Example 1 was performed using the anaerobic biological treatment apparatus shown in FIG. The wastewater to be biologically treated in Example 1 is TMAH-containing actual wastewater discharged from a semiconductor factory, and is subjected to separation treatment so that 90% by weight or more of the entire organic matter becomes TMAH. And the TMAH density | concentration in this real waste_water | drain was adjusted so that it might become 8000 mgTMAH / L. Next, after adding anaerobic sludge (sludge concentration: 23000 mg / L) as seed sludge to the first reaction tank having an internal volume of 1.5 L, the actual waste water is 10 kg TMAH / m ³ / d (5.4 kg TOC / in TOC load). Water was passed through with a TMAH load of m ³ / d). Further, the waste water in the first reaction tank is supplied to a second reaction tank (internal volume 1.2 L) in which a solid-liquid separation device using a 0.4 μm PVDF hollow fiber membrane is installed in the tank, and 0 Suction filtered at 3 m / d. The solid-liquid separation treatment was performed in a cycle of 7 minutes suction filtration and 1 minute stop.

  The temperature when draining water into the first reaction tank was adjusted to 30 ° C. and the pH to 7-8. Further, 0.16 mL of nutrient (85% phosphoric acid), 5 mL / L of trace elements (Orgamine 10 manufactured by Organo Corporation), and 0.4 mg / L of Ni and Co were added.

(Comparative Example 1)
In Comparative Example 1, waste water treatment was performed by passing the same waste water as in Example 1 through a UASB treatment device using anaerobic granules. In addition, the treated water discharged | emitted from UASB was supplied to the waste_water | drain at the time of flowing in into a UASB processing apparatus, and the TMAH density | concentration in waste_water | drain was adjusted so that it might become 8000 mgTMAH / L. When the treatment apparatus was started up, the TMAH concentration was adjusted by supplying industrial water to the waste water flowing into the UASB treatment apparatus. The TMAH load at the start-up of the processing apparatus was set to 1 kg TMAH / m ³ / d and increased while checking the processing status. Other processing conditions were the same as in Example 1.

FIG. 4 shows the TMAH concentration and TMAH load in the treated water obtained in Example 1. FIG. 5 shows changes over time in the suction pressure of the filtration membrane used in Example 1. FIG. 6 shows the TMAH concentration and TMAH load in the treated water obtained in Comparative Example 1. As shown in FIG. 4, in the first embodiment, be subjected to a treatment with (5.4kgTOC ^{/ m} 3 ^/ d in the TOC load) and high load TMAH load 10kgTMAH ^/ m 3 ^/ d, obtained by Example 1 It has been found that the TMAH concentration in the treated water, that is, the treated water discharged from the membrane separation device does not increase even after 30 days, and that TMAH can be stably removed even at a high load. Moreover, as shown in FIG. 5, the suction pressure of the filtration membrane did not change. That is, it was confirmed that there was almost no clogging of the filtration membrane, and membrane treatment with a stable flux was possible. On the other hand, in Comparative Example 1, the TMAH concentration in the treated water obtained in Comparative Example 1 hardly increased with a TMAH load of ³ kg TMAH / m ³ / d from about 10 days after the start of water flow. However, after 14 days from the start of water flow, the anaerobic granules in the UASB treatment device were refined and flowed out of the UASB treatment device, and the TMAH concentration in the treated water discharged from the UASB treatment device increased. On the 20th day from the start of water flow, the TMAH removal rate decreased to about 50%, and stable treatment could not be performed.

(Example 2)
The wastewater to be biologically treated in Example 2 is an actual wastewater containing methanol discharged from a semiconductor factory, and is subjected to a separation treatment so that 90% by weight or more of the whole organic matter becomes methanol. And the TMAH density | concentration in this real waste_water | drain was adjusted so that it might become 10000 mg / L. Next, after adding anaerobic sludge (sludge concentration: 23000 mg / L) as seed sludge to the first reaction tank having an internal volume of 1.5 L, the actual waste water is added to 12 kg CODcr / m ³ / d (3.2 kg TOC / at TOC load). Water was passed with a CODcr load of m ³ / d). Further, the waste water in the first reaction tank was supplied to a second reaction tank (internal volume 1.2 L) in which a filtration device using a 0.4 μm PVDF hollow fiber membrane was installed in the tank, and 0.3 m / D was filtered by suction.

  The temperature when draining water into the first reaction tank was adjusted to 30 ° C. and the pH to 7-8. In addition, 0.3 g / L of nutrient (Orgamine NP-51, manufactured by Organo Corp.), 3 mL / L of trace element (Orgamine 10 manufactured by Organo Corp.), 0.3 mg / L each of Ni and Co Added.

FIG. 7 shows the methanol concentration and CODcr load in the treated water obtained in Example 2. FIG. 8 shows changes over time in the suction pressure of the filtration membrane used in Example 2. As shown in FIG. 7, in Example 2, be subjected to a treatment at a high load (3.2kgTOC ^{/ m} 3 ^/ d in the TOC load) and CODcr load 10kgCODcr ^/ m 3 ^/ d, obtained by Example 2 It has been found that the methanol concentration in the treated water, that is, the treated water discharged from the membrane separation apparatus, can be stably removed without increasing even after 25 days. Moreover, as shown in FIG. 8, the suction pressure of the filtration membrane hardly changed. That is, it was confirmed that there was almost no clogging of the filtration membrane, and membrane treatment with a stable flux was possible even under high load.

(Example 3)
In Example 3, the sludge density | concentration of the anaerobic sludge thrown into the 1st reaction tank with an internal volume of 1.5L was changed to 0-40000 mg / L, and the viscosity in each sludge density | concentration was measured. The sludge concentration of the anaerobic sludge was adjusted by dilution with industrial water or concentration by centrifugation, and the sludge viscosity was measured using a viscometer (manufactured by Lion Co., Ltd., Viscotester VT-03E).

  FIG. 9 is a diagram summarizing the relationship between the sludge concentration and the viscosity of the anaerobic sludge of Example 3. As shown in FIG. 9, when the sludge concentration (MLSS) exceeded 35000 mg / L, it was confirmed that the sludge viscosity rapidly increased. By controlling the operation so that the sludge concentration in the reaction tank is 35000 mg / L or less, the clogging of the membrane of the subsequent membrane separation apparatus is further suppressed, and thus it can be said that processing with a high load becomes possible.

  1-3 Anaerobic biological treatment apparatus, 10 Raw water first line, 12 Raw water tank, 14 Raw water second line, 16 First reaction tank, 17 Second reaction tank, 19 Treatment liquid discharge line, 20 Treated water discharge line, 22 Gas discharge line, 24 Concentrated water return line, 26, 27 Membrane separation device, 30 Nutrient storage tank, 32 Nutrient supply line, 34 pH adjuster storage tank, 36 pH adjuster supply line, 38 Stirrer, 40a, 40b Partition plate , 42 Solid-liquid separation part, 44 Communication path, 46 Processing liquid extraction part.

Claims (9)

A biological treatment process for methane fermentation of wastewater containing organic matter having 6 or less carbon atoms under anaerobic conditions, and a membrane separation process for separating the treatment liquid obtained in the biological treatment process into sludge and treated water by a filtration membrane. Have
An anaerobic biological treatment method comprising adjusting a biological sludge concentration in the biological treatment step to a range of 15000 to 35000 mg / L.   The anaerobic biological treatment method according to claim 1, wherein the organic substance is at least one of tetramethylammonium hydroxide and methanol.   The anaerobic biological treatment method according to claim 1 or 2, wherein the waste water is adjusted so that the organic matter is single and contains 90% by weight or more of the total organic matter in the waste water. The anaerobic organism according to any one of claims 1 to 3, wherein in the biological treatment step, biological treatment is performed at a CODcr load of 10 kg / m ³ / d or more or a TMAH load of 5 kg / m ³ / d. Processing method. A reaction tank for methane fermentation of wastewater containing organic matter having 6 or less carbon atoms under anaerobic conditions, and a membrane separation unit for separating the treatment liquid obtained in the reaction tank into sludge and treated water by a filtration membrane ,
An anaerobic biological treatment apparatus, wherein the biological sludge concentration in the reaction tank is adjusted to a range of 15000 to 35000 mg / L.   The anaerobic biological treatment apparatus according to claim 5, wherein the organic substance is at least one of tetramethylammonium hydroxide and methanol.   The anaerobic biological treatment apparatus according to claim 5, wherein the membrane separation unit is provided outside the reaction tank.   The anaerobic apparatus according to any one of claims 5 to 7, further comprising means for adjusting the waste water so that the organic matter is single and contains 90% by weight or more of the total organic matter in the waste water. Sex biological treatment equipment. The anaerobic organism according to any one of claims 5 to 8, wherein in the reaction vessel, biological treatment is carried out at a CODcr load of 10 kg / m ³ / d or more or a TMAH load of 5 kg / m ³ / d. Processing equipment.

Images