JP5443057B2 - Anaerobic biological treatment method and anaerobic biological treatment apparatus - Google Patents

Description

  The present invention relates to a biological treatment method for anaerobically biologically treating wastewater containing tetramethylammonium hydroxide (hereinafter sometimes simply referred to as TMAH), alkylammonium salts such as choline, or organic substances having a small carbon number, and the like. The present invention relates to a biological treatment apparatus.

  Conventionally, when sludge discharged from pulp manufacturing wastewater processes or chemical factories is treated with anaerobic wastewater mainly containing organic matter having 2 or less carbon atoms such as acetic acid, ethanol or acetaldehyde, granule sludge Is dismantled to reduce the particle size, the amount of sludge is reduced and the treatment becomes unstable.

  In normal anaerobic treatment, the cross-linking effect of anaerobic hydrolyzing bacteria that decompose high molecular carbohydrates, proteins, and lipids into low molecules, 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, methanogenic bacteria are the main biota with few hydrolyzing bacteria and acid-producing bacteria. 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.

  Conventionally, as specific examples of these countermeasures, for example, methods of Patent Documents 1 to 4 have been proposed.

Japanese Patent No. 4193310 JP 2008-279383 A Japanese Patent No. 2563004 JP 2008-279385 A

  The method of Patent Document 1 relates to an anaerobic biological treatment method in which a polymer flocculant is added to prevent the granular sludge from collapsing after the granule sludge is introduced and the treatment is started. It is difficult to start up the treatment by introducing the activated sludge and to form the granular sludge from the anaerobic sludge. In addition, when the polymer flocculant is added over a long period of time, there is a concern that the charge between the polymer flocculants repels and the granular sludge is dispersed. Another problem is that the polymer flocculant is expensive.

  In addition, the method of Patent Document 2 is an anaerobic biological treatment method in which nitric acid and nitrous acid are added. However, since nitric acid and nitrous acid, which are originally targeted for wastewater treatment, are actively added, fluctuations in raw water, equipment troubles, etc. When trouble occurs in operation management, etc., nitrogen is discharged together with the treated water, which may cause water pollution. In addition, in this method, it is necessary to coexist denitrifying bacteria and methanogenic bacteria, and considering that the anaerobic reaction starts after the denitrification reaction occurs, the quality of treated water deteriorates due to fluctuations in raw water, nitric acid, etc. There is concern about the possibility of leakage into treated water.

  In addition, the method of Patent Document 3 is an anaerobic treatment method in which acetic acid is added four times as much as methanol, which is a treatment target substance, at the time of start-up. Not right. Further, in this method, since acetic acid injection is stopped after the start-up, granule stability and processing stability after a predetermined period from the stop of acetic acid injection pose problems.

  Moreover, the method of patent document 4 is an anaerobic processing method which adds carbohydrate. Here, carbohydrates are carbohydrates, and include monosaccharides that are simple substances, oligosaccharides that are several condensates, and polysaccharides (starch, cellulose, chicken, etc.) that consist of many monosaccharides. Monosaccharides include triose having 3 carbon atoms, tetrose having 4 carbon atoms, pentose having 5 carbon atoms, hexose having 6 carbon atoms, and the like. In such anaerobic biological treatment in which monosaccharides are added, there is a concern about the collapse of granule sludge. Therefore, it is not considered that the addition of carbohydrates is necessarily useful for preventing the collapse of granule sludge. In addition, in the method, only specific examples of starch are shown among saccharides. And when starch is used, since starch is hardly soluble in water, there is a problem in operation management and the like that must be dissolved once in hot water to form a solution.

  As described above, since each of the above methods has problems, practical application is difficult. In addition, each of the above methods is an example of wastewater containing organic matter having 1 carbon such as methanol discharged in the pulp manufacturing process, and discharged from a process using pure water or ultrapure water in a semiconductor manufacturing factory or the like. There are no examples of anaerobic biological treatment of alkyl ammonium salt-containing wastewater (which may contain resist-derived resin or surfactant) such as used TMAH-containing wastewater containing 4 carbon atoms.

  An object of the present invention is to provide an anaerobic biological treatment method that satisfactorily treats wastewater containing an alkylammonium salt or organic matter having 6 or less carbon atoms, particularly wastewater containing TMAH, choline, etc. discharged from a semiconductor manufacturing factory or the like. And providing an anaerobic biological treatment apparatus.

The present invention is an anaerobic biological treatment method for anaerobically biologically treating wastewater containing an alkylammonium salt discharged from a semiconductor manufacturing plant using granules , wherein molasses is added to the wastewater at a total organic carbon ratio. It supplies so that it may become 1 to 10% of the said waste_water | drain .

Further, the reference example is an anaerobic biological treatment method for anaerobically biologically treating wastewater containing an organic substance having 6 or less carbon atoms, and molasses is supplied to the wastewater.

  In the anaerobic biological treatment method, it is preferable to supply the molasses at the time of starting and after the biological treatment.

  In the anaerobic biological treatment method, it is preferable that anaerobic sludge is introduced into a reaction tank in which the biological treatment is performed to start up the biological treatment.

  In the anaerobic biological treatment method, the waste water is preferably discharged from a semiconductor manufacturing factory.

  In the anaerobic biological treatment method, the alkyl ammonium salt or the organic substance having 6 or less carbon atoms is preferably tetramethylammonium hydroxide (TMAH).

  In the anaerobic biological treatment method, it is preferable to fill a reaction tank in which the biological treatment is performed with a carrier when the biological treatment is started up.

The anaerobic biological treatment apparatus of the present invention includes a reaction tank for anaerobically biologically treating wastewater containing alkylammonium salts discharged from a semiconductor manufacturing plant using granules , and molasses is added to the wastewater as a whole organic matter. Molasses supply means for supplying the carbon dioxide so as to be 1 to 10% of the waste water .

Moreover, the anaerobic biological treatment apparatus of a reference example is provided with the reaction tank which carries out the anaerobic biological treatment of the waste_water | drain containing C6 or less organic substance, and the molasses supply means which supplies molasses to the said waste_water | drain.

  In the anaerobic biological treatment apparatus, it is preferable that the molasses supply means supplies molasses at the time of starting and after the biological treatment.

  In the anaerobic biological treatment apparatus, it is preferable that anaerobic sludge is put into the reaction tank when the biological treatment is started up.

  In the anaerobic biological treatment apparatus, the waste water is preferably discharged from a semiconductor manufacturing factory.

  In the anaerobic biological treatment apparatus, the alkyl ammonium salt or the organic substance having 6 or less carbon atoms is preferably tetramethylammonium hydroxide (TMAH).

  In the anaerobic biological treatment apparatus, when the biological treatment is started, the reaction tank is preferably filled with a carrier.

  According to the present invention, wastewater containing an alkylammonium salt or an organic substance having 6 or less carbon atoms, particularly wastewater containing TMAH, choline, etc. discharged from a semiconductor manufacturing plant or the like can be treated well.

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 a figure which shows the sludge particle size before water flow and 36 days after water flow. It is a figure which shows the 50 times magnified photograph of the sludge before water flow, the Example after 36 days of water flow, and the sludge of Comparative Examples 1-3. It is a figure which shows the sludge density | concentration in the column before a water flow and 55 days after a water flow. It is a figure which shows the sludge interface height in the column before water flow and after 55 days of water flow.

  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 regulation tank 12, a raw water second line 14, a reaction tank 16, a treated water discharge line 20, a gas discharge line 22, and a treated water circulation line 24. , Molasses supply means, nutrient supply means, and pH adjuster supply means. The molasses supply means is composed of a molasses storage tank 26 and a molasses supply line 28, the nutrient supply means is composed of a nutrient preparation reservoir 30 and a nutrient supply line 32, and the pH adjuster supply means is pH adjustment. It comprises an agent storage tank 34 and a pH adjusting agent supply line 36. However, the configuration of each supply means 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 adjustment 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 adjustment tank 12. The molasses discharge port (not shown) of the molasses storage tank 26 and the molasses supply port (not shown) of the adjustment tank 12 are connected by a molasses supply line 28, and the nutrient supply outlet (not shown) of the nutrient storage tank 30 and the adjustment tank. The 12 nutrient supply ports (not shown) are connected by a nutrient supply line 32, and the pH adjuster discharge port (not shown) of the pH adjustment tank 12 and the pH adjuster supply port (not shown) of the adjustment tank 12. The space is connected by a pH adjuster supply line 36. The raw water outlet (not shown) of the adjustment 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 separator 42 is provided with an overflow-type treated water outlet 46, and the treated water discharge line 20 is connected to a treated water outlet (not shown) of the treated water outlet 46. Further, a treated water circulation line 24 is connected between the treated water return port (not shown) of the treated water outlet 46 and the treated water supply port (not shown) of the adjustment tank 12. A gas discharge line 22 is connected to the top of the reaction tank 16.

  The reaction tank 16 may be any tank that can mainly biologically treat alkylammonium salts anaerobically, and an upflow sludge bed type reaction using granules represented by the UASB method, the EGSB method, and the like. A tank, a fixed bed type fluidized bed type reaction tank using a carrier, or the like can be used.

  Below, the operation | movement of the anaerobic biological treatment apparatus 1 of this embodiment and the anaerobic biological treatment method are demonstrated.

  The alkylammonium salt-containing wastewater is supplied from the raw water first line 10 to the adjustment tank 12, and the molasses in the molasses storage tank 26 is supplied from the molasses supply line 28 to the adjustment tank 12. The mixed solution (alkyl ammonium salt-containing wastewater and molasses) mixed by the stirring device 38 is introduced into the reaction tank 16 from the raw water second line 14 and is passed therethrough in an upward flow. According to the knowledge of the present inventor, it is considered that the alkylammonium salt (for example, TMAH) is decomposed into methane, carbonate ion, ammonium ion, and the like by the anaerobic organism in the reaction tank 16. The seed sludge used for anaerobic biological treatment is not particularly limited. For example, anaerobic sludge and granules used in food factories, beverage factories, paper factories, chemical factories, livestock wastewater treatment, etc. Or digested sludge from a sewage treatment plant.

  In the prior art, it has been disclosed that granule sludge containing anaerobic microorganisms is introduced into the reaction tank 16 from the start of biological treatment, and anaerobic treatment is performed. By adding it, it is possible to form granular sludge from anaerobic sludge. Therefore, anaerobic sludge can be introduced into the reaction tank 16 to start up biological treatment.

  In the present embodiment, it is preferable that the molasses is supplied at the start and after the start of the biological treatment. The supply amount of molasses is not particularly limited, but for example, it is preferable to supply molasses so that the total organic carbon ratio is 0.5 to 20% of the target wastewater, and the total organic carbon ratio is More preferably, the molasses is supplied so as to be 1 to 10% of the target waste water.

  The present inventors have found that granule sludge can be formed from anaerobic sludge by adding molasses in anaerobic biological treatment, and the refinement of granule sludge can be suppressed. It came. As the cause of the above effect by the addition of molasses, for example, molasses is a high molecular organic substance, so that the growth of hydrolyzing bacteria and acid producing bacteria is promoted, and a biopolymer having a crosslinked structure of granules is produced, and This is considered to be because filamentous Methanosaeta genus, an acetic acid-assimilating methanogenic bacterium, can be grown. In addition, for example, molasses contains essential trace elements necessary for the growth of microorganisms in addition to organic substances, and it is considered that these trace elements contribute to the promotion of granulation. The above trace elements are deficient in factory effluents using pure water and ultrapure water in semiconductor manufacturing factories, etc., but by adding molasses, essential trace elements necessary for the growth of microorganisms are replenished. Therefore, the refinement | miniaturization etc. of granule sludge are suppressed and the stable process is attained.

  In addition, in order to increase the amount of granules at the start of biological treatment, substances that promote the formation of granules such as activated carbon, iron and calcium salts, fly ash, or flocculants and organic substances are added. May be.

  Here, “molasses (including waste molasses)” in the present specification refers to sugarcane (cane molasses) produced from sugarcane juice or when raw sugar is refined or sugar beet sugar is added from sugar beet. It is a by-product (sticky brown liquid with a large specific gravity) that is generated during sugar production, such as during production. Molasses contains 40-60% sugar. Moreover, since molasses is generally a by-product of the sugar refining process, sucrose (disaccharide of glucose and fructose) is the main component. In addition, molasses contains protein, fat, minerals, amino acids, vitamins and the like. The raw material of molasses is not particularly limited, and examples include sugarcane, sweet potato, brown sugar, corn, raw sugar, sugar beet and the like. The molasses used in the present embodiment may be molasses, and the molasses is more preferable in terms of cost. In addition, the starch used by patent document 4 (Unexamined-Japanese-Patent No. 2008-279385) is a general term for the glucose polymer which D-glucopyranose continued in the alpha-1 / 4 bond.

  As described above, in the reaction tank 16, the alkylammonium salt (eg, TMAH) is decomposed into methane, carbonate ions, ammonium ions, etc. by an anaerobic organism (mainly after the start of biological treatment). Then, the waste water that has been subjected to the anaerobic biological treatment enters the solid-liquid separation unit 42 from the communication path 44, and the treated water that has undergone solid-liquid separation overflows and flows to the treated water extraction unit 46, and is taken out from the treated water discharge line 20. 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.

  In the present embodiment, part of the treated water after biological treatment is supplied from the treated water circulation line 24 to the adjustment tank 12 and flows into the reaction tank 16 (when biologically treated) in the alkylammonium salt-containing wastewater. The alkylammonium salt concentration is preferably 20000 mg / L or less, and more preferably 10,000 mg / L or less. In particular, when there is a concern about fluctuations in water quality or the influence of coexisting substances, the alkylammonium salt concentration in the wastewater containing alkylammonium salt when flowing into the reaction tank 16 (biological treatment) should be 5000 mg / L or less. Is preferable, and the range of 1000 to 3000 mg / L is more preferable. Here, in this embodiment, when the alkylammonium salt concentration in the alkylammonium salt-containing wastewater exceeds at least 20000 mg / L, the treated water may be supplied and diluted to a concentration of 20000 mg / L or less. However, even if the alkylammonium salt concentration in the wastewater containing alkylammonium salt is 20000 mg / L or less (for example, 10000 mg / L or more), treated water is supplied, for example, 10000 mg / L or less or 1000 to 3000 mg / L You may dilute to the range of L. When the alkylammonium salt concentration in the wastewater containing alkylammonium salt when flowing into the reaction tank 16 exceeds 20000 mg / L, the decomposition reaction rate of the alkylammonium salt may be slow during biological treatment.

  In the present embodiment, for example, a sensor for detecting the ammonium ion concentration in the treated water after biological treatment may be installed in the treated water discharge line 20 or the like. Then, the alkylammonium salt concentration is estimated from the detected ammonium ion concentration, and the amount of treated water added is determined based on the estimated value so that the alkylammonium salt concentration when flowing into the reaction tank 16 falls within the above range. It is preferable to do. Further, for example, a sensor that detects the alkylammonium salt concentration may be installed in the adjustment tank 12 or the raw water first line 10. And based on the detected alkyl ammonium salt density | concentration, you may determine the addition amount of treated water so that the alkyl ammonium salt density | concentration at the time of flowing in into the reaction tank 16 may become the said range.

  In addition, when the ammonium ion concentration in the reaction tank 16 exceeds 5000 mg / L, the decomposition reaction rate decreases. Therefore, a part of the treated water after biological treatment is supplied from the treated water circulation line 24 to the adjustment tank 12 to react. The ammonium ion concentration in the tank 16 is preferably 5000 mg / L or less, and more preferably 1000 mg / L or less.

  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. You may dilute the alkyl ammonium salt containing waste water 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 to promote the decomposition reaction of the alkylammonium salt.

  In this embodiment, when biologically treating the alkylammonium salt-containing wastewater, the pH adjuster is preferably such that the pH is in the range of 6.5 to 9.0, more preferably in the range of 7.0 to 8.0. It is preferable to supply the pH adjuster from the supply line 36 to the adjustment tank 12. If the pH of the alkylammonium salt-containing wastewater is outside the above range, the decomposition reaction rate of the alkylammonium salt by biological treatment may decrease. Conventionally, in anaerobic biological treatment, weak acidity at pH 6.5 to 7 was preferred in order to suppress ammonia inhibition. However, regarding treatment with alkylammonium salt, the weak alkali side at pH 7 to 8 was used. Thus, the processing performance is the best. This is what the present inventors have clarified for the first time. Here, when adjusting pH to the said range, it is preferable that the alkyl ammonium salt density | concentration in an alkyl ammonium salt containing waste water shall be 20000 mg / L or less and an ammonium ion density | concentration shall be 5000 mg / L or less.

  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 activity of anaerobic organisms satisfactorily, for example, it is preferable to supply the nutrient to the adjustment tank 12 from the nutrient supply line 32. 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 this embodiment, when biologically treating the alkylammonium salt-containing wastewater, the temperature of the water in the reaction tank 16 is preferably adjusted to 20 ° C. or higher, and the temperature is adjusted to be in the range of 28 to 35 ° C. It is more preferable. The decomposition of the alkyl ammonium salt by the anaerobic biological treatment is possible even at a temperature lower than 20 ° C. However, if it is lower than 20 ° C., the decomposition reaction rate is lowered, so the water temperature is preferably adjusted to the above range. The temperature adjustment method is not particularly limited. For example, the water temperature in the reaction tank 16 may be adjusted by supplying steam to the adjustment 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. Further, for example, methane gas is generated by the decomposition of the alkylammonium salt, but after the desulfurization treatment is carried out in the same manner as a normal anaerobic treatment, it is recovered as thermal energy with a methane gas boiler, the thermal energy is supplied to the reaction tank 16, and the water temperature is increased. You may adjust. Here, when adjusting the water temperature in the reaction tank 16 to the above range, the alkylammonium salt concentration in the alkylammonium salt-containing waste water is preferably 20000 mg / L or less and the ammonium ion concentration is 5000 mg / L or less.

  Although the alkylammonium salt-containing wastewater has been described as an example of wastewater to be subjected to anaerobic treatment in the present embodiment, anaerobic treatment can be similarly performed with organic matter-containing wastewater having 6 or less carbon atoms.

  In treating alkylammonium salt-containing wastewater and organic matter-containing wastewater containing 6 or less carbon atoms (for example, isopropyl alcohol, monoethanolamine, etc.) discharged from processes using pure water or ultrapure water at semiconductor manufacturing plants, etc. In conventional anaerobic biological treatment methods, granule sludge is generated at the time of start-up, granule sludge is maintained after the start-up (ie, suppression of granule sludge refinement), and long-term treatment performance is maintained. There's a problem. In addition, as a conventional treatment method other than the anaerobic biological treatment method, various treatment methods such as distillation concentration treatment, treatment using an ion exchange resin, and membrane treatment have been proposed. There is an environmental problem. However, as in the present embodiment, molasses is added even in wastewater containing alkylammonium salt or wastewater containing organic matter having 6 or less carbon atoms discharged from a process using pure water or ultrapure water such as a semiconductor manufacturing factory. So, for example, the generation of granular sludge at startup, maintenance of granule sludge after startup, and long-term stable treatment, as well as good anaerobic in terms of economy, operation management, and environment Biological treatment can be realized. Here, waste water discharged from a semiconductor manufacturing factory in this specification includes waste water discharged from a factory that manufactures semiconductors such as IC and LSI, liquid crystal panels, and the like.

  The alkylammonium salt to be treated in this embodiment is, for example, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, trimethylethylammonium. Hydroxide, dimethyldiethylammonium hydroxide, trimethyl (2-hydroxyethyl) ammonium hydroxide (ie choline), triethyl (2-hydroxyethyl) ammonium hydroxide, dimethyldi (2-hydroxyethyl) ammonium hydroxide, diethyldi (2 -Hydroxyethyl) ammonium hydrooxy Id, methyltri (2-hydroxyethyl) ammonium hydroxide, ethyltri (2-hydroxyethyl) ammonium hydroxide, tetra (2-hydroxyethyl) ammonium hydroxide, and their salts, and the like. This embodiment is particularly suitable for the treatment of tetramethylammonium hydroxide (TMAH) and trimethyl (2-hydroxyethyl) ammonium hydroxide (that is, choline) discharged from a semiconductor manufacturing factory or the like.

  The treatment target of this embodiment can also be applied to the treatment of organic substances having 6 or less carbon atoms. For example, the above alkyl ammonium salts having 6 or less carbon atoms, isopropyl alcohol (IPA), methanol, monoethanolamine, acetic acid, propylene Examples include glycol monomethyl ether (PGME), cyclohexanone, dimethyl sulfoxide (DMSO), and propylene glycol methyl ether acetate (PGMEA).

  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 separation tank 18 is installed at the subsequent stage of the reaction tank 16, and a return line 48 for returning the sludge separated by the separation tank 18 to the reaction tank 16 as necessary is provided. It has been. The return line 48 is provided between the separation tank 18 and the reaction tank 16. With the above configuration, when biological treatment is started up, sludge that has flowed into the treated water due to fluctuations in the raw water or the like can be collected in the separation tank 18 and returned to the reaction tank 16 from the return line 48 again. The separation tank 18 is not particularly limited, for example, a coagulation-precipitation process in which a coagulant is added and processed, a pressure levitation process, or the like. Further, when the treated water is significantly foamed, it is preferable to add an antifoaming agent when the treated water is supplied to the separation tank 18.

  In addition, when the alkylammonium salt-containing wastewater contains SS components such as a resist and a surfactant, a separation tank capable of separating and removing the SS components is further installed in the previous stage of the reaction tank 16. Is preferred. When the alkylammonium salt-containing wastewater is treated in the reaction tank 16, even if a resist or a surfactant is mixed in, it does not affect biological treatment. By installing the tank, clogging of the processing apparatus due to the SS component can be prevented.

  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 2 shown in FIG. 2, and the description is abbreviate | omitted. A carrier 50 is filled in the reaction tank 16 of the anaerobic biological treatment apparatus 3 shown in FIG. When the biological treatment is started up, the carrier 50 is filled in the reaction tank 16 to form and maintain granule sludge, shorten the biological treatment start-up period, and improve the wastewater treatment stability. it can. The type of carrier used in the present embodiment is not particularly limited. For example, a sponge carrier such as polyurethane, a gel carrier such as polyvinyl alcohol (PVA), a fibrous carrier, a non-woven fabric molded product, or a product made of polypropylene. Examples include molded products. The form of the molded product is not particularly limited, and various forms such as a net-like skeleton body such as a honeycomb type and a V-type, a net-like mat shape, a net-like pipe shape, and a net-like ball shape are possible. Although not shown, it is more preferable to install a gas-solid-liquid separator at the upper part in the reaction tank filled with the carrier.

  Further, since the treatment water obtained by biologically treating the alkylammonium salt-containing wastewater in the reaction tank 16 contains ammoniacal nitrogen, it is preferable to install a nitrogen treatment tank in the subsequent stage of the reaction tank 16. The nitrogen treatment tank may be a generally known nitrogen treatment apparatus, for example, biological treatment such as nitrification-denitrification-reoxidation treatment, nitritation-anammox treatment, ammonia distillation, stripping treatment, etc. And an apparatus capable of performing the physicochemical treatment. Further, by partially circulating the treated water, mixing it with waste water, and performing the TMAH treatment after the stripping treatment, it is possible to reduce the load of the nitrogen biological treatment in the subsequent stage.

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

(Example)
After adjusting the actual waste water containing TMAH discharged from the semiconductor factory to 2000 mg TMAH / L, anaerobic sludge (sludge concentration 25148 mg / L) was added as a seed sludge to the column with an internal volume of 0.8 L, and half of the column was added. The actual waste water was passed through with a load of 5 kg TMAH / m 3 / d. The temperature during water flow was adjusted to 35 ° C. and the pH to 7-8. Further, a nutrient (Orgamine NP-51 manufactured by Organo Corp.), trace elements (Orgamine 10 manufactured by Organo Corp. 1.2 mL / L), Ni and Co (each 0.1 mg / L) were added. In addition, waste molasses (sugar cane and sweet potato as raw materials) was added to the actual waste water continuously from the start-up so that it was 200 mg / L (57 mg C / L, TOC ratio was 5.3% with respect to TMAH). . The components of the molasses used in the examples have a sugar content of 30 to 40% or more, a pure sugar ratio of 35% or more, a reducing sugar of 15% or more, and a pure sugar content of 55% or more. Other components are shown in Table 1.

(Comparative Example 1)
The comparative example 1 performed the process similar to an Example except not adding molasses.

(Comparative Example 2)
The comparative example 2 performed the process similar to an Example except having added ferric chloride (inorganic flocculant) instead of molasses so that it might become 19 mg / L (6.5 mgFe / L as iron).

(Comparative Example 3)
In Comparative Example 3, the same treatment as in Example was performed except that 0.5 mg / L of a cationic polymer (polymer flocculant: OX-606 manufactured by Organo Corporation) was added instead of molasses.

  FIG. 4 is a diagram showing the sludge particle size before water passage and after 36 days of water passage. FIG. 5: is a figure which shows the 50 times enlarged photograph of the sludge before water flow, the Example after 36 days of water flow, and the sludge of Comparative Examples 1-3. FIG. 6 is a diagram showing the sludge concentration in the column before passing water and 55 days after passing water. FIG. 7 is a diagram showing the sludge interface height in the column before passing water and 55 days after passing water.

  As can be seen from FIG. 4 and FIG. 5, it was confirmed that the particle size of the sludge was larger in Examples than in Comparative Examples 1 to 3, and granulation was promoted. Moreover, as can be seen from FIG. 6 and FIG. 7, the example shows that the sludge concentration and the sludge interface height are increased as compared with Comparative Examples 1 to 3, and the amount of sludge maintained in the column is increased. confirmed. In particular, the effect of addition of the cationic polymer, which was conventionally effective in the anaerobic treatment of methanol, was not clear, but the effect of this example was clear and very effective for promoting and maintaining the formation of granules. It was confirmed.

  1-3 Anaerobic biological treatment equipment, 10 Raw water first line, 12 Adjustment tank, 14 Raw water second line, 16 Reaction tank, 18 Separation tank, 20 Treated water discharge line, 22 Gas discharge line, 24 Treated water circulation line, 26 Molasses storage tank, 28 Molasse supply line, 30 nutrient storage tank, 32 nutrient supply line, 34 pH regulator storage tank, 36 pH regulator supply line, 38 stirrer, 40a, 40b partition plate, 42 solid-liquid separator, 44 stations Passage, 46 treated water outlet, 48 return line, 50 carrier.

Claims (10)

  An anaerobic biological treatment method for anaerobically biologically treating wastewater containing alkylammonium salts discharged from a semiconductor manufacturing plant using granules, wherein molasses is added to the wastewater in a ratio of total organic carbon to the wastewater. An anaerobic biological treatment method characterized by supplying 1 to 10%. Anaerobic biological treatment method according to claim 1, characterized in that after the launch and during start-up of the biological treatment, supplying the molasses. The anaerobic biological treatment method according to claim 1 or 2 , wherein anaerobic sludge is introduced into a reaction tank for performing the biological treatment to start up the biological treatment. The anaerobic biological treatment method according to claim 1, wherein the alkylammonium salt is tetramethylammonium hydroxide (TMAH). The anaerobic biological treatment method according to claim 3 , wherein a carrier is filled in a reaction tank for performing the biological treatment when the biological treatment is started. A reaction tank that anaerobically biologically treats wastewater containing alkylammonium salt discharged from a semiconductor manufacturing plant using granules;
An anaerobic biological treatment apparatus comprising: molasses supply means for supplying molasses to the wastewater so that the total organic carbon ratio is 1 to 10% of the wastewater. The anaerobic biological treatment apparatus according to claim 6, wherein the molasses supply means supplies the molasses at the time of starting and after the biological treatment. The anaerobic biological treatment apparatus according to claim 6 or 7 , wherein anaerobic sludge is put into the reaction tank when the biological treatment is started up. The anaerobic biological treatment apparatus according to claim 6 , wherein the alkylammonium salt is tetramethylammonium hydroxide (TMAH). The anaerobic biological treatment apparatus according to claim 8 , wherein when the biological treatment is started up, the reaction tank is filled with a carrier.