JP2016101538A - Method for biologically treating waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for biologically treating waste water, in which when the waste water contains both of a sulfur-based COD component and a nitrogen component is treated under an oxygen-free sulfur oxidation condition, the rate of an oxygen-free sulfur oxidation reaction can be accelerated without necessitating a continuous or intermittent charge of a substance for activating metabolism of bacteria and without further necessitating membrane separation treatment.SOLUTION: The method for biologically treating waste water containing the sulfur-based COD component and the nitrogen component comprises the steps of: throwing a solid electron acceptor substance, which is functioned as an electron acceptor, in a reaction tank to proliferate denitrifying sulfur oxidation bacteria in the presence of the electron acceptor substance; and treating the proliferated denitrifying sulfur oxidation bacteria in the reaction tank under the oxygen-free sulfur oxidation condition so that the sulfur-based COD component in the waste water is oxidized and reduced and the nitrogen component is removed as a gas.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a biological treatment method for waste water.

Applied to wastewater containing sulfur-based COD components, that is, reducing sulfur components (for example, wastewater containing at least one of S ²⁻ , HS ⁻ , SO ₃ ²⁻ , S ₂ O ₃ ²⁻ , SCN ⁻ ). As a biological treatment method, a treatment method using sulfur-oxidizing bacteria is well known. In this wastewater treatment method using sulfur-oxidizing bacteria, there are aerobic sulfur oxidation and anaerobic sulfur oxidation as reaction pathways for sulfur oxidation.

In the treatment method under aerobic sulfur oxidation conditions, the sulfur-based COD component serves as an electron donor, and molecular oxygen serves as an electron acceptor to cause a sulfur oxidation reaction. For example, aerobic sulfur-oxidizing bacteria belonging to the genus Pseudomonas (Patent Document 1), the Paracoccus genus (Non-Patent Document 1), and the like perform this reaction. On the other hand, in the treatment method under anaerobic sulfur oxidation conditions, sulfur-based COD components serve as electron donors, and nitrite ions (NO ₂ ⁻ ) and nitrate ions (NO ₃ ⁻ ) serve as electron acceptors and sulfur. occurs denitrification, NO ₂ becomes electron acceptor ^- and NO ₃ ^- is a nitrogen-containing gas _{(NO, N 2 O, N} 2 , etc. gas) so vaporized is to be removed, sulfur-COD components And the nitrogen component can be removed simultaneously. For example, denitrifying sulfur-oxidizing bacteria belonging to the genus Thiobacillus (Patent Document 2), the genus Thioalkalivibrio (Non-Patent Documents 2 and 3), and the like perform this reaction.

  Unlike the treatment method under the aerobic sulfur oxidation condition, the treatment method under the anaerobic sulfur oxidation condition is excellent in that the sulfur-based COD component and the nitrogen component can be removed simultaneously. However, the treatment method under the anaerobic sulfur oxidation condition has a problem that the reaction rate is slower than the treatment method under the aerobic sulfur oxidation condition by the aerobic sulfur oxidation bacteria. Therefore, if the reaction rate can be increased in the treatment method under anaerobic sulfur oxidation conditions, the sulfur-based COD component and nitrogen component that cannot be realized by the treatment method under aerobic sulfur oxidation conditions should be removed simultaneously. And wastewater treatment can be performed efficiently.

  As a method of increasing the reaction rate of this oxygen-free sulfur oxidation, conventionally, a method using a granular material or a massive material in which calcium carbonate and sulfur coexist is used to activate the metabolism of denitrifying sulfur-oxidizing bacteria. (Patent Document 3) and a method of improving the treatment efficiency by preventing sludge from flowing out of the reaction tank by incorporating sludge containing denitrifying sulfur-oxidizing bacteria into the water-absorbent resin and fixing it comprehensively ( Patent literature 4), a method for improving the treatment efficiency by adopting a membrane separation activated sludge treatment method, maintaining a high concentration of denitrifying sulfur-oxidizing bacteria in the reaction tank, and the like (patent literature 5) are proposed. .

The method of Patent Document 3 is a wastewater treatment method using a denitrifying sulfur-oxidizing bacterium characterized by using a granular material or a massive material in which calcium carbonate and sulfur coexist as a composition for imparting microbial activity, The above-mentioned granular substance or lump becomes a nutrient substrate for the denitrifying sulfur-oxidizing bacteria and activates the denitrifying sulfur-oxidizing bacteria.
However, since the particulates or lumps used as the composition for imparting microbial activity in this method are consumed by the denitrifying sulfur-oxidizing bacteria, it is necessary to add them continuously or intermittently during wastewater treatment. However, this method has a problem that processing costs increase.

In the method of Patent Document 4, the sewage sludge incineration ash and the incineration ash suspension are added to and mixed with the sludge containing denitrifying sulfur-oxidizing bacteria, and the water absorbent resin is further added to and mixed with the sludge. This is a technology that takes in the water-absorbing resin and fixes it in a fixed manner, thereby preventing the sludge containing denitrifying sulfur-oxidizing bacteria from flowing out of the reaction tank and improving the processing efficiency.
However, in this method, the surface of the sludge immobilized and immobilized is peeled off over time, and microorganisms other than denitrifying sulfur-oxidizing bacteria adhere to the surface of the sludge immobilized and immobilized. Another problem in operation is that only denitrifying sulfur-oxidizing bacteria cannot be accumulated at high concentrations.

The method of Patent Document 5 is a membrane separation activated sludge treatment method using denitrifying sulfur-oxidizing bacteria, and the denitrifying sulfur-oxidizing bacteria can be maintained at a high concentration in the reaction tank, so that the treatment efficiency can be improved. it can.
However, in the membrane separation activated sludge method, in order to prevent clogging of the membrane, it is necessary to periodically perform membrane cleaning (chemical cleaning) with chemicals such as hypochlorous acid or backwashing, and chemical cleaning In this case, there is a problem that the treatment needs to be stopped and the cost of the medicine is increased, and in the case of backwashing, the treatment needs to be stopped, and a washing container for backwashing There is a problem that a place for cleaning is required.

Japanese Unexamined Patent Publication No. 08-323,390 JP-A-11-299,481 Japanese Patent Laid-Open No. 11-285,377 Japanese Unexamined Patent Publication No. 5-138,193 JP 2002-316,189

Katayama, et al., Paracoccus thiocyanatus sp. Nov., A new species of thiocyanate-utilizing facultative chemolithotroph, and transfer of Thiobacillus versutus to the genus Paracoccus as Paracoccus versutus comb. -1477, 1995 Sorokin, DY. Et al., Denitrification at extremely high pH values by the alkaliphilic, obligately chemolithoautotrophic, sulfur-oxidizing bacterium Thioalkalivibrio denitrificans ALJD, Archives of Microbiology, 175, 94-101, 2001 Sorokin, DY. Et al., Thioalkalivibrio nitratireducens sp. Nov., a nitrate-reducing member of an autotrophic denitrifying consortium from a soda lake., International Journal of Systematic and Evolutionary Microbiology, 53, 1779-1783, 2003

  As described above, in wastewater containing both sulfur-based COD components and nitrogen components such as water-activated activated sludge treated water, the biological treatment method under anaerobic sulfur oxidation conditions that can treat both of them simultaneously performs wastewater treatment. Although considered simple and advantageous, this method has the problem of slow reaction rates and is intended to increase reaction rates during biological treatments under this anaerobic sulfur oxidation condition. In the conventional method, the processing cost increases, such as the necessity of continuous or intermittent input of a substance that activates bacterial metabolism, another operational problem, or the necessity of chemical washing or back washing. There was a problem.

  The present invention is a method for treating wastewater containing both a sulfur-based COD component and a nitrogen component under anoxic sulfur oxidation conditions, and it is not necessary to continuously or intermittently add a substance that activates bacterial metabolism. An object of the present invention is to provide a biological treatment method for wastewater that can increase the reaction rate of anaerobic sulfur oxidation while requiring no membrane separation treatment.

In view of this, the present inventor believes that in biological treatment under anaerobic sulfur oxidation conditions by a denitrifying sulfur-oxidizing bacterium, electrons taken out from the sulfur-based COD component (electron donor) are ultimately nitrogen components. Focusing on being transferred to nitrite ions and nitrate ions (electron acceptors), solid substances that function as electron acceptors in addition to nitrite ions and nitrate ions in this reaction under anoxic sulfur oxidation conditions If (electron acceptor substance) is present, the total capacity of the electron acceptor, which is a delivery destination of electrons extracted from the sulfur-based COD component, is increased, and the transfer of electrons is facilitated, so that the decomposition rate of the sulfur-based COD component is increased. If the solid electron acceptor substance is a substance that is not substantially consumed by microorganisms such as denitrifying sulfur-oxidizing bacteria, it can be continuously or intermittently used during wastewater treatment. Added to Considered it unnecessary that further actually a result of the verification of these ideas are selected nitrogen components with reducing sulfur-COD components in waste water by oxidizing NO, from the group consisting of N 2 _O and N ₂ The present invention has been completed by finding that it can be efficiently removed as one or more gases.

That is, the gist of the present invention is as described in the following (1) to (6).
(1) Contains at least one selected from the group consisting of S ²⁻ , HS ⁻ , SO ₃ ²⁻ , S ₂ O ₃ ²⁻ , and SCN ⁻ as the sulfur-based COD component, and NO ₂ as the nitrogen component ^- and NO ₃ ^- a biologically processing method for waste water containing a reaction vessel and,
A solid electron acceptor substance that functions as an electron acceptor is put into the waste water in the reaction tank, and denitrifying sulfur-oxidizing bacteria are grown in the presence of this electron acceptor substance,
The waste water is treated under anaerobic sulfur oxidation conditions in the reaction vessel to oxidize and reduce the sulfur-based COD component in the waste water, and the nitrogen component is selected from the group consisting of NO, N ₂ O and N ₂ A method for biological treatment of wastewater, characterized in that it is removed as one or more gases.
(2) The denitrifying sulfur-oxidizing bacteria grown in the waste water in the presence of a solid electron acceptor substance are bacteria contained in the activated sludge put into the waste water together with the electron acceptor substance, and The biological treatment method of wastewater according to (1) above, wherein the bacteria are contained in the wastewater.
(3) Said (1) or (2), wherein said electron acceptor substance is one or more selected from the group consisting of magnetite, zeolite, and a mixture of pyrite and chalcopyrite A biological treatment method of waste water as described in 1.
(4) the drainage is at least SCN as the sulfur-based COD components ^- the characterized in that it contains (1) to the biological treatment method of the waste water according to any one of (3).
(5) The biological treatment method for wastewater according to any one of (1) to (4), wherein the wastewater is treated with water-activated activated sludge.
(6) The biological treatment of wastewater according to any one of (1) to (4), wherein the wastewater is wastewater obtained by mixing blast furnace slag immersion water with water-activated activated sludge treated water. Method.

  According to the present invention, a solid electron acceptor substance functioning as an electron acceptor is charged into a reaction vessel, and wastewater containing a sulfur-based COD component and a nitrogen component is treated under anoxic sulfur oxidation conditions. Compared with the conventional method in which the electron acceptor substance is not charged into the reaction vessel, these sulfur-based COD components and nitrogen components can be removed more efficiently and more easily.

FIG. 1 is an explanatory diagram of a denitrifying sulfur-oxidizing bacterium used in a biological treatment method of wastewater by an oxygen-free sulfur oxidation reaction. FIG. 2 is an explanatory diagram showing an example of a test apparatus for confirming that electrons flow into a solid electron acceptor substance functioning as an electron acceptor. FIG. 3 is an explanatory diagram showing an example of the biological wastewater treatment process of the present invention. FIG. 4 is an explanatory diagram showing an example of a metabolic reaction of a denitrifying sulfur-oxidizing bacterium using thiocyanic acid as an electron donor and nitrite nitrogen or nitrate nitrogen as an electron acceptor. FIG. 5 is an explanatory diagram showing an example of the metabolic reaction of denitrifying sulfur-oxidizing bacteria and denitrifying bacteria in an environment where a solid electron acceptor substance coexists.

The present invention relates to a sulfur-based COD component (one or more selected from the group consisting of S ²⁻ , HS ⁻ , SO ₃ ²⁻ , S ₂ O ₃ ²⁻ , and SCN ⁻ ) and a nitrogen component (NO ₂ ⁻ and NO ₃ ^-) and a biological treatment method of the waste water for treating the waste water containing in the electron acceptor substance solids which functions as an electron acceptor in the reaction vessel was charged, the drainage anaerobic sulfur The wastewater is treated under oxidizing conditions to oxidize and reduce the sulfur-based COD component in the wastewater and to remove the nitrogen component as one or more gases selected from the group consisting of NO, N ₂ O and N ₂ . Biological treatment method. Here, the oxygen-free sulfur oxidation condition in the present invention means that dissolved oxygen is not present in the waste water, but dissolved in a state where nitrite nitrogen (NO ₂ ⁻ ) and nitrate nitrogen (NO ₃ ⁻ ) are present. This is a condition in which not sulfur oxidation using oxygen as an electron acceptor but sulfur oxidation using nitrite nitrogen or nitrate nitrogen as an electron acceptor.

The wastewater to be treated in the present invention is a sulfur-based COD component (one or more selected from the group consisting of S ²⁻ , HS ⁻ , SO ₃ ²⁻ , S ₂ O ₃ ²⁻ , and SCN ⁻ ) and a nitrogen component. (NO ₂ ^- and NO 3 ^_-) is not a subject to any particular limitation so long as it contains, for example, aqueous ammonia activated sludge treated water, blast furnace slag steep water, ammonia liquor activated sludge treated water in these blast furnace slag soaking water , Wastewater generated from petroleum refining industry, photographic industry, chemical industry, leather industry, metal refining industry, mine, and the like. Here, the blast furnace slag immersion water is drainage generated by contact of blast furnace slag with rainwater or the like. Blast furnace slag contains reducing sulfur compounds (sulfur-based COD) and is stored in the yard, so the blast furnace slag immersion water generated when it comes into contact with rainwater contains sulfur-based COD components. Reducing sulfur is included, and the pH is about 12.

Each of the above-described wastewater contains a sulfur-based COD component, but the nitrogen component is small, and conversely, the nitrogen component is contained, but the sulfur-based COD component may be small. . In such a case, for example, drainage containing nitrogen components such as water-activated activated sludge treated water is added in an appropriate amount, or drainage containing sulfur-based COD components such as blast furnace slag immersion water is necessary. The present invention can be applied by adding an appropriate amount so that the wastewater to be treated contains both the sulfur-based COD component and the nitrogen component. Since these are drainage, the cost does not increase. Incidentally, NO ₂ contained in the waste water ^- and NO ₃ ^- are little if it contains only one, in most cases contain both even in small amounts.

  In addition, the present invention is a biological treatment method of wastewater, and when the denitrifying sulfur-oxidizing bacteria are contained in the wastewater to be treated, the denitrifying sulfur-oxidizing bacteria are grown and drained. May be biologically treated, and if the wastewater to be treated does not contain denitrifying sulfur-oxidizing bacteria or if it is contained in a small amount, this denitrifying sulfur-oxidizing bacteria The activated sludge containing the wastewater may be added to the wastewater, and the added denitrifying sulfur-oxidizing bacteria are grown to biologically treat the wastewater.

  In the present invention, the solid electron acceptor substance that is charged into the reaction vessel and functions as an electron acceptor in the reaction vessel is an oxygen-free sulfur oxidation reaction by a denitrifying sulfur-oxidizing bacterium that occurs in the reaction vessel. Any solid substance that can receive electrons generated at the time and is not consumed by denitrifying sulfur-oxidizing bacteria in wastewater or difficult to consume, and is not particularly limited, for example, magnetite, Zeolite, mixture of pyrite and chalcopyrite, mixture of pyrite and sphalerite, mixture of pyrite and sphalerite, mixture of chalcopyrite and sphalerite, mixture of chalcopyrite and sphalerite, zinc blende 1 type or 2 or more types chosen from the group which consists of a mixture of an ore and a bright ore, carbon fiber, etc. are mentioned. Since these substances are hardly consumed due to their low solubility, in most cases they need only be added once, and the cost of adding them again does not increase.

  The amount of the solid electron acceptor substance charged into the reaction vessel is preferably 10% or more and 50% or less in volume ratio with respect to the volume of the reaction vessel of 100%. If it is less than 10%, the microorganism group containing denitrifying sulfur-oxidizing bacteria and the solid electron acceptor substance cannot be sufficiently contacted in the reaction tank, and the sulfur-based COD component and nitrogen component in the wastewater It may not be removed sufficiently. On the contrary, if it is 50% or more, the volume occupied by the mixture of the microorganism group containing denitrifying sulfur-oxidizing bacteria and the wastewater with respect to the volume of the reaction tank becomes small, the hydraulic residence time becomes too short, The sulfur-based COD component and nitrogen component may not be sufficiently removed. However, even if it is 50% or more, if it is allowed to reduce the inflow rate of the wastewater into the reaction tank and take sufficient hydraulic residence time, the sulfur-based COD component and nitrogen component in the wastewater will be sufficiently removed. Can be removed.

  In addition, the solid electron acceptor substance should have a large specific surface area. This is because the exchange of electrons between the solid electron acceptor substance functioning as the electron acceptor and the microorganism group including the denitrifying sulfur-oxidizing bacteria is performed more efficiently when the specific surface area is larger. . The particle size range of the solid electron acceptor substance is preferably 0.5 mm or more and 30 mm or less. If it is less than 0.5 mm, it may be suspended in the wastewater and flow out with the treated water. Conversely, if it is more than 30 mm, the specific surface area becomes too small and it is difficult to exchange electrons efficiently. is there.

The present invention relates to a biological treatment method for growing denitrifying sulfur-oxidizing bacteria to remove or reduce sulfur-based COD components and nitrogen components in wastewater, which can be carried out as follows. it can.
When using activated sludge containing denitrifying sulfur-oxidizing bacteria, put solid electron acceptor substance and activated sludge containing denitrifying sulfur-oxidizing bacteria in the reaction tank, and drain the wastewater upward or downward. Let it flow continuously. In order to maintain an oxygen-free state in the reaction tank, stirring is not performed, or stirring is gently performed so as not to entrain air so that the activated sludge and the waste water are efficiently in contact with each other. Regarding the temperature at which the wastewater flows into the reaction tank and the hydraulic retention time of the wastewater in the reaction tank, the temperature is such that the microorganisms in the activated sludge can grow, and the inflowing sulfur-based COD components and nitrogen What is necessary is just the residence time of the waste water in which the removal rate of these components by the microorganism group is equal to or higher than the loading rate of the components, and usually the temperature is about 5 to 40 ° C., and the hydraulic residence time Is preferably about 1 to 24 hours.

  In addition, when denitrifying sulfur-oxidizing bacteria in the wastewater are grown without putting activated sludge in the reaction tank, only the solid electron acceptor substance is put in the reaction tank, and the wastewater is flowed upward or downward. The denitrifying sulfur-oxidizing bacteria contained in the waste water may be allowed to grow in the reaction tank continuously by flowing in the flow. In this case, it is preferable that part or all of the treated water once extracted from the reaction tank is returned to the reaction tank and circulated, thereby effectively removing the denitrifying sulfur-oxidizing bacteria contained in the waste water. Can be grown.

  Here, the microorganisms that can be applied in the wastewater biological treatment method of the present invention are those that can decompose and remove sulfur-based COD components and nitrogen components in wastewater under anoxic sulfur oxidation conditions. Although not particularly limited, a typical example thereof will be described. As shown in FIG. 1, for example, a species of the genus Thiobacillus denitrificans that grows in the pH range of approximately 5.5 to 8.5. The genus Thiobacillus (patent document 2), which generally grows in the range of pH 6.0 to pH 9.5 (Non-patent document 1), and grows in the range of approximately pH 7.5 to pH 10.5 Thioalkalivibrio genus (Niopatent literature 2), such as the genus Thioalkalivibrio genus Denitrificans (isolate), and approximately pH 8.5 to pH10 5 land Contact alkaline Vibrio to grow in the range of (Thioalkalivibrio) genus Knightly Thiry du sense (Nitratireducens) species (isolate) such as thio alkali Vibrio (Thioalkalivibrio) genus (non-patent document 3) or the like can be exemplified.

Next, a method for confirming that electrons flow into a solid electron acceptor substance functioning as an electron acceptor will be described.
For example, it can be confirmed using the test apparatus shown in FIG. In this test apparatus, the center of the container body is divided into half tanks by a proton exchange membrane 6 and is constituted by two tanks. One tank is a negative electrode tank 3 and the other tank is a positive electrode tank 4. It is said that.

  In this test apparatus, the negative electrode tank 3 and the positive electrode tank 4 are each filled with an equal amount of a mixture of the water-activated activated sludge treated water 7 and the activated sludge. Here, as the activated sludge to be put into the negative electrode tank 3 and the positive electrode tank 4, it is preferable to use one that has been acclimatized under anaerobic sulfur oxidation conditions using the water-activated activated sludge treated water in advance. The denitrifying sulfur-oxidizing bacteria 1 are grown in the activated sludge put into the negative electrode tank 3, and the denitrifying bacteria 2 are grown in the activated sludge put into the positive electrode tank 4. Here, the denitrifying bacterium 2 is a denitrifying bacterium other than the denitrifying sulfur-oxidizing bacterium 1, and examples thereof include the genus Marinobacter and the genus Pseudomonas. Can do.

  Next, two solid substances to be measured for examining whether or not the substance functions as an electron acceptor (herein, described as “electron acceptor substance 5” functioning as an electron acceptor) are respectively positive electrodes. The negative electrode 3 and the negative electrode 3 are connected to each other by a conductive wire 8, one of which is placed in the negative electrode vessel 3, and the other is placed in the positive electrode vessel 4. The voltage between the positive electrode tank 4 can be measured.

When the inside of the negative electrode tank 3 and the positive electrode tank 4 of the test apparatus configured as described above is put into an oxygen-free state (either left without stirring, gently stirred, or gently with nitrogen gas or argon gas) In the negative electrode tank 3, for example, electrons are extracted from thiocyanic acid (SCN ⁻ ) by an oxygen-free sulfur oxidation reaction by the denitrifying sulfur-oxidizing bacteria 1, and one of the extracted electrons is Part is transferred to the solid electron acceptor material 5. Then, the electrons transferred to the electron acceptor material 5 in the negative electrode tank 3 reach the solid electron acceptor material 5 in the positive electrode tank 4 through the conductive wire 8, and then are received by the denitrifying bacteria 2, Using the received electrons, the denitrifying bacterium 2 reduces nitrite nitrogen (NO ₂ ⁻ ) and nitrate nitrogen (NO ₃ ⁻ ) to nitrogen gas (N ₂ ). At this time, since a potential difference is generated between the negative electrode tank 3 and the positive electrode tank 4, if this potential difference is measured by the voltmeter 10, a solid electron acceptor material 5 in which the substance to be measured functions as an electron acceptor. It is confirmed that

Subsequently, the biological wastewater treatment process using the wastewater treatment apparatus shown in FIG. 3 is taken as an example, and the case where the wastewater is a safe activated sludge treated water and the activated sludge is used as an example. Specific embodiments will be described in detail.
First, the low-water activated sludge treated water is put into the drainage tank 3. In this case, when the wastewater is a wastewater obtained by mixing the blast furnace slag soaked water with the water-activated activated sludge treated water, for example, the blast furnace slag soaked water is placed in the drainage tank 1 and the water-activated activated sludge treated water is discharged. The waste water is put into the tank 2, and both waste waters are sent to the waste water tank 3 by the liquid feed pump 13 and the liquid feed pump 14, and mixed. The waste water tank 3 produces waste water for processing.

  In the drainage tank 3, the pH of the wastewater is adjusted to a desired range in consideration of the growth pH region of the microorganism group used for biological wastewater treatment. Here, since the pH of the blast furnace slag immersion water is about 12 and the pH of the low-water activated sludge treatment water is about 8 to 9, it is produced depending on the mixing ratio of the low-water activated sludge treatment water to the blast furnace slag immersion water. In some cases, the pH of the mixed wastewater is higher than the desired pH value range (for example, pH 5.5 to 10.5). In that case, seawater with pH buffering action is added. And mixing to lower the pH to within the desired pH value range. In such a case, as a method of adding seawater, for example, after preparing a mixed wastewater in which blast furnace slag immersion water is mixed with water-activated activated sludge treated water in the drainage tank 3, the seawater is put into the drainage tank 1 or 2. The required amount may be sent to the drainage tank 3 to adjust the pH, and a seawater tank (not shown) is provided in the drainage tanks 1 and 2, and the required amount of seawater is sent from the seawater tank to the drainage tank 3. You may adjust pH by.

  Next, in the reaction tank 4, a solid electron acceptor substance 5 that functions as an electron acceptor is charged, and activated sludge is charged. The activated sludge may be activated sludge that treats domestic wastewater or safety water, etc., preferably activated sludge that has been acclimatized in advance with wastewater mixed with low-water activated sludge treated water or blast furnace slag soaked water. It is good to be. Thereafter, the wastewater from the drainage tank 3 is passed through the reaction tank 4 by the liquid feed pump 15, becomes a mixture 6 of activated sludge and wastewater in the reaction tank 4, and is necessary for processing in the reaction tank 4. The mixture 6 of activated sludge and waste water is retained for a time (hydraulic residence time). At the same time, while the pH sensor 7 is monitoring so that the pH of the wastewater in the reaction tank 4 is maintained at 5.5 or more and 10.5 or less, the acid solution is again supplied from the acid tank 8 by the liquid feed pump 16. The alkaline solution is fed from the alkaline tank 9 by the liquid feed pump 17 as necessary, and the pH of the mixture 6 of the activated sludge and the wastewater staying in the reaction tank 4 is adjusted. The pH adjustment range of the mixture 6 of the activated sludge and waste water staying in the reaction tank 4 is specifically determined by the growth pH region of the microorganism group to be used, but is generally known denitrification. The pH range in which oxidative sulfur-oxidizing bacteria can grow is 5.5 to 10.5, and the same applies to denitrifying sulfur-oxidizing bacteria contained in activated sludge and denitrifying sulfur-oxidizing bacteria contained in waste water. It can grow in the pH range. However, when the activated sludge is acclimatized in advance, the pH adjustment range should be approximately the same as the pH adjustment range at the time of acclimatization, and it is considered that the activated sludge acclimatized has a higher activity. It is done.

  In the waste water treatment apparatus shown in FIG. 3, the upflow type reaction tank 4 is taken as an example, but a downflow type reaction tank may be used. Further, in order to maintain the inside of the reaction vessel 4 in an oxygen-free state, it is preferable that stirring is not performed, stirring is performed gently so as not to entrain air, or the gas is gently aerated with nitrogen gas, argon gas, or the like. Also, the activated sludge and the waste water are made to contact efficiently. The drainage of water into the reaction tank 4 may be intermittent. However, in order to stably propagate the microorganisms in the activated sludge and to efficiently treat the wastewater, It is preferable to pass water. The mixture 6 of activated sludge and waste water overflows into the activated sludge settling tank 10 and separates into treated water 11 and activated sludge 12, and the activated sludge 12 is returned into the reaction tank 4 by a liquid feed pump 18.

The microorganisms containing the denitrifying sulfur oxidizing bacteria in the activated sludge, Sulfur denitrification of sulfur-COD components and nitrogen components in the waste water takes place, for the sulfur denitrification reaction, for example, SCN ^- and NO ₃ ^- as if the following reaction formula (1) and, also, S ₂ O ₃ ^2-and NO ₃ ^- as long as the reaction of as follows equation (2), be written respectively it can. Furthermore, SCN ^- and NO ₂ ^- if the reaction of as in the following equation (3), _also, S ₂ ^{O 3 2-and} NO ₂ ^- and as if the following reaction formula (4) Can be described respectively.

Formula (1)
^{_{5SCN - + 8NO 3 - + H}} 2 O → 5SO 4 2- + 5CNO - + 4N 2 + 2H +
Formula (2)
5S ₂ O ₃ ²⁻ + 8NO ₃ ⁻ + H ₂ O → 10SO ₄ ²⁻ + 4N ₂ + 2H ⁺
Formula (3)
3SCN ⁻ + 8NO ₂ ⁻ + 2H ⁺ → 3CNO ⁻ + 3SO ₄ ²⁻ + 4N ₂ + H ₂ O
Formula (4)
3S ₂ O ₃ ²⁻ + 8NO ₂ ⁻ + 2H ⁺ → 6SO ₄ ²⁻ + 4N ₂ + H ₂ O

Here, regarding the reaction of the formula (1) and the formula (3), as shown in FIG. 4, the denitrifying sulfur-oxidizing bacterium 1 itself generates electrons generated by oxidation of SCN ⁻ as NO ³⁻ or NO ^2−. It can be understood that this is a delivery reaction route used for the reduction of. In the present invention, by introducing a solid electron acceptor substance 5 that functions as an electron acceptor into the reaction vessel 4, as shown in FIG. 5, in addition to the reaction path shown in FIG. A new reaction pathway has been formed in which denitrifying sulfur-oxidizing bacteria 1 passing through body material 5 transfer electrons to other denitrifying sulfur-oxidizing bacteria 1 and other denitrifying bacteria 2, and this reaction pathway has increased. The decomposition reaction of the sulfur-based COD component and the nitrogen component by the sulfur denitrification reaction is accelerated by the amount. Therefore, the method of the present invention can be applied to any reaction route as long as the electron is transferred from the electron donor to the electron acceptor. For example, phenol (C ₆ H ₅ OH) Is an electron donor, and can also be applied to a phenol denitrification reaction in which nitrite nitrogen (NO ₂ ⁻ ) or nitrate nitrogen (NO ₃ ⁻ ) serves as an electron acceptor.

  After the sulfur-based COD component and the nitrogen component in the wastewater are simultaneously removed by the sulfur denitrification reaction of the above formulas (1) to (4), the mixture 6 of activated sludge and wastewater overflows from the reaction tank 4. Is sent to the activated sludge settling tank 10 and discharged out of the system. Here, when the sulfur-based COD component and the nitrogen component remain in the treated water 11, the treated water 11 is returned to the drainage tank 3 to perform the circulation treatment, and the sulfur-based COD component can be discharged to the environment. Remove the nitrogen component.

In the present invention, the sulfur-based COD component and nitrogen component may be quantified as long as the sulfur-based COD component and nitrogen component can be quantified over time or intermittently. For example, COD uses potassium permanganate. According to the acidic high temperature permanganate method (hereinafter referred to as COD _Mn ), S ²⁻ , HS ⁻ , SO ₃ ²⁻ and S ₂ O ₃ ²⁻ are analyzed by iodine titration method, and SCN ⁻ is mixed with nitric acid. after adjusting the pH to acidic by adding, with nitric acid solution of ferric thiocyanate ferric spectrophotometric method in which color development was added and further, NO ₂ ^- by ion chromatography for, ^- and NO ₃ Each can be quantified.

  As explained in the above embodiments, according to the present invention, the water-activated activated sludge treated water, which is a waste water containing a sulfur-based COD component and a nitrogen component, can be treated independently, and blast furnace slag immersion water In addition, wastewater mixed with water-activated activated sludge treated water can be treated in the same manner.

  Hereinafter, although an example of implementation of this invention implemented using the waste water treatment apparatus shown in FIG. 3 is shown, this invention is not limited to these Examples.

[Example 1]
Wastewater to be treated contains sulfur-based COD components and nitrogen components shown in Table 1 and pH 8.3 and COD _Mn : 150 mg / L of water-activated sludge treated water is used. 3 and into the reaction vessel 4, magnetite (with a particle size adjusted in the range of 0.5 mm to 30 mm) as the solid electron acceptor material 5 is added and the above-mentioned water-activated activated sludge treated water is used. The activated sludge that had been acclimatized under anaerobic sulfur oxidation conditions was added. At this time, the input amount of magnetite (electron acceptor material 5) was 20% with respect to the volume of the reaction tank 4, and the pH adjustment range when the activated sludge was acclimatized was 8.0 to 9.0. It was.

The hydraulic retention time of the wastewater in the reaction tank 4 is set to 2 hours, and the water-activated activated sludge treated water in the drainage tank 3 is caused to flow into the reaction tank 4 by the liquid feed pump 15 to adjust the pH of the wastewater in the reaction tank 4 to 8 The wastewater treatment was performed while adjusting to 0.0 to 9.0, and the quality of the treated water 11 in the activated sludge settling tank 10 was examined one week after the start of the wastewater treatment. The results are as shown in Table 1, and the low-water activated sludge treated water has been treated to COD _Mn to 15 mg / L or less of the target value, and each of NO ₂ ⁻ and NO ₃ ⁻ has the target value. It was processed to 10 mg / L or less.

[Example 2]
Without putting activated sludge in the reaction tank 4, only the magnetite is added as the solid electron acceptor material 5, and the waste water is continuously flowed into the reaction tank 4 at a flow rate with a hydraulic retention time of 2 hours. Part (50% by volume) of the waste water was circulated by providing a circulation route for returning the activated sludge settling tank 10 to the drainage tank 3, and denitrifying sulfur-oxidizing bacteria contained in the drainage were grown in the reaction tank 4 for 20 days. Except for this, when biological treatment of water-reduced activated sludge treated water was carried out under the same conditions as in Example 1, denitrifying sulfur-oxidizing bacteria in the wastewater proliferated and, as shown in Table 1, A result almost equivalent to that in Example 1 was obtained.

Example 3
Except that zeolite (having a particle size adjusted to 0.5 mm or more and 30 mm or less) was charged as a solid electron acceptor material 5 in the reaction tank 4, the living water sludge treated water was treated under the same conditions as in Example 1 above. The water quality of the obtained treated water 11 was investigated.
As a result, as shown in Table 1, the low-water activated sludge treated water was treated so that COD _Mn was 15 mg / L or less of the target value, and each of NO ₂ ⁻ and NO ₃ ⁻ was 10 mg / L of the target value. Processed below L.

Example 4
A mixture of pyrite and chalcopyrite as a solid electron acceptor substance 5 in the reaction vessel 4 (mixed in a ratio of 50% by mass to 50% by mass with a particle size adjusted to 0.5 mm to 30 mm, respectively). Except that it was added, biological treatment of the low-water activated sludge treated water was carried out under the same conditions as in Example 1, and the water quality of the obtained treated water 11 was examined.
As a result, as shown in Table 1, the low-water activated sludge treated water was treated so that COD _Mn was 15 mg / L or less of the target value, and each of NO ₂ ⁻ and NO ₃ ⁻ was 10 mg / L of the target value. Processed below L.

[Comparative Example 1]
As a control system for Examples 1, 3, and 4, low water was used in the same manner as in Examples 1, 3, and 4 except that the solid electron acceptor material 5 was not introduced into the reaction vessel 4. Biological treatment of activated sludge treated water was carried out, and the quality of the treated water 11 obtained was examined.
As a result, as shown in Table 1, the low-water activated sludge treated water was not treated until COD _Mn was 15 mg / L or less of the target value, and the target value of NO ₂ ⁻ and NO ₃ ⁻ was 10 mg of the target value. Not processed below / L.

[Comparative Example 2]
As a control system for Examples 1, 3, and 4, the reaction was carried out except that quartzite (having a particle size adjusted to 0.5 mm or more and 30 mm or less) was introduced as a solid substance that did not function as an electron acceptor in the reaction vessel 4. In the same manner as in Examples 1, 3, and 4, the biological treatment of the water-activated activated sludge treated water was carried out, and the quality of the obtained treated water 11 was examined.
As a result, as shown in Table 1, the low-water activated sludge treated water was not treated until COD _Mn was 15 mg / L or less of the target value, and the target value of NO ₂ ⁻ and NO ₃ ⁻ was 10 mg of the target value. Not processed below / L.

Example 5
The wastewater to be treated contains sulfur-based COD components shown in Table 1 and has pH 12.0 and COD _Mn : 49 mg / L blast furnace slag immersion water, and contains sulfur-based COD components and nitrogen components shown in Table 1, pH 8.3 and COD _Mn : 150 mg / L of low-water activated sludge treated water is used, the blast furnace slag immersion water is put into the drain tank 1, and the low-water activated sludge treated water is put into the drain tank 2, The mixture was sent to the drainage tank 3 by the feed pump 13 and the feed pump 14 and mixed to prepare a mixed wastewater in which the blast furnace slag immersion water and the water-activated activated sludge treated water were mixed at a mixing ratio of 1: 3 by volume. .

Using the mixed wastewater produced above as wastewater to be treated, the pH adjustment range when acclimatizing activated sludge under anoxic sulfur oxidation conditions using the above mixed wastewater in advance is 8.5 to 9.5. In addition, except that the pH of the waste water in the reaction tank 4 was adjusted to 8.5 to 9.5, biological treatment of the mixed waste water was carried out in the same manner as in Example 1 above, and the treated water obtained Eleven water qualities were examined.
As a result, as shown in Table 1, the mixed waste water is treated so that COD _Mn is 15 mg / L or less of the target value, and each of NO ₂ ⁻ and NO ₃ ⁻ is 10 mg / L or less of the target value. It has been processed.

Example 6
Biological treatment of the mixed wastewater was carried out under the same conditions as in Example 5 above, except that zeolite (having a particle size adjusted to 0.5 mm or more and 30 mm or less) was charged as the solid electron acceptor material 5 in the reaction vessel 4. The water quality of the treated water 11 obtained was examined.
As a result, as shown in Table 1, the waste water obtained by mixing the blast furnace slag immersion water with the water-activated activated sludge treated water is treated until the COD _Mn is 15 mg / L or less of the target value, and NO ₂ ^- and NO ₃ ^- each of which is processed to below 10 mg / L of the target value of.

Example 7
Mixed waste water under the same conditions as in Example 5 above, except that a mixture of pyrite and chalcopyrite (particle size adjusted to 0.5 mm or more and 30 mm or less) as a solid electron acceptor material 5 was put into the reaction vessel 4. The biological treatment was conducted and the water quality of the obtained treated water 11 was examined.
As a result, as shown in Table 1, the waste water obtained by mixing the blast furnace slag immersion water with the water-activated activated sludge treated water is treated until the COD _Mn is 15 mg / L or less of the target value, and NO ₂ ^- and NO ₃ ^- each of which is processed to below 10 mg / L of the target value of.

[Comparative Example 3]
As a control system of Examples 5 to 7, biological treatment of the mixed waste water was carried out in the same manner as in Examples 5 to 7 except that the solid electron acceptor substance 5 was not introduced into the reaction vessel 4. Then, the water quality of the obtained treated water 11 was examined.
Results are as shown in Table 1, mixed wastewater, _{COD Mn} is not processed until the following 15 mg / L of the target value, also, NO ₂ ^- and NO ₃ ^- both 10 mg / L or less of the target value also It was not processed until.

[Comparative Example 4]
As a control system of Examples 5 to 7, Example 5 was used except that silica (as the particle size was adjusted to 0.5 mm or more and 30 mm or less) as a solid substance that did not function as an electron acceptor was put in the reaction vessel 4. Biological treatment of the mixed waste water was carried out in the same manner as in No. 7, and the water quality of the obtained treated water 11 was examined.
Results are as shown in Table 1, mixed wastewater, _{COD Mn} is not processed until the following 15 mg / L of the target value, also, NO ₂ ^- and NO ₃ ^- are both below 10 mg / L of the target value also Was not processed until.

  1, 2, 3, ... Drain tank, 4 ... Reaction tank, 5 ... Solid electron acceptor substance that functions as an electron acceptor, 6 ... Mixture of activated sludge and waste water, 7 ... pH sensor, 8 ... Acid tank, 9 DESCRIPTION OF SYMBOLS ... Alkali tank, 10 ... Activated sludge settling tank, 11 ... Treated water, 12 ... Activated sludge, 13-15, 18 ... Liquid feed pump, 16 ... Acid pump, 17 ... Alkaline pump.

Claims (6)

It contains at least one selected from the group consisting of S ²⁻ , HS ⁻ , SO ₃ ²⁻ , S ₂ O ₃ ²⁻ , and SCN ⁻ as the sulfur-based COD component, and NO ₂ ⁻ and NO as the nitrogen component. ₃ ^- a biologically processing method for waste water containing a reaction vessel and,
A solid electron acceptor substance that functions as an electron acceptor is put into the waste water in the reaction tank, and denitrifying sulfur-oxidizing bacteria are grown in the presence of this electron acceptor substance,
The waste water is treated under anaerobic sulfur oxidation conditions in the reaction vessel to oxidize and reduce the sulfur-based COD component in the waste water, and the nitrogen component is selected from the group consisting of NO, N ₂ O and N ₂ A method for biological treatment of wastewater, characterized in that it is removed as one or more gases.   The denitrifying sulfur-oxidizing bacteria grown in the waste water in the presence of a solid electron acceptor substance are bacteria contained in the activated sludge introduced into the waste water together with the electron acceptor substance, and / or The biological treatment method of wastewater according to claim 1, wherein the wastewater is a bacterium contained in the wastewater.   The wastewater organism according to claim 1 or 2, wherein the electron acceptor substance is one or more selected from the group consisting of magnetite, zeolite, and a mixture of pyrite and chalcopyrite. Processing method. The drainage is at least SCN as the sulfur-based COD components ^- biological treatment method of the waste water according to any one of claims 1 to 3, characterized in that it contains.   The biological treatment method for wastewater according to any one of claims 1 to 4, wherein the wastewater is treated with water-activated activated sludge.   The biological wastewater treatment method according to any one of claims 1 to 4, wherein the wastewater is wastewater obtained by mixing low-water activated sludge treated water with blast furnace slag immersion water.

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