JP2006326522A - Method for controlling water treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling water treatment without causing a delay in taking countermeasures, without depending on the capability of an operator and capable of maintaining treatment performance by specifying indicator bacteria which provide an indicator of the treatment performance in a water treatment process. <P>SOLUTION: In the method for controlling water treatment which controls the treatment performance of the water treatment process, the water treatment process which removes an object substance to be treated from treated water supplied to a water treatment tank using a plural kinds of bacteria comprises a selection process for selecting the indicator bacteria providing the indicator of the treatment performance from a group consisting of the plural kinds of bacteria, a measurement process for measuring the number of indicator bacteria in the water treatment tank and a holding process for holding the indicator bacteria of a predetermined number or more in the water treatment tank. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water treatment management method.

  Conventionally, in water treatment processes where wastewater from various production facilities (factories), etc., and treated water such as sewage are treated with bacteria, the amount of activated sludge (activated sludge concentration) is one of the maintenance management indicators, exceeding the required amount. Wastewater treatment has been carried out by maintaining the amount of activated sludge. However, even if the amount of activated sludge is maintained above the necessary amount, the processing performance may be insufficient.

  On the other hand, in the water treatment process, it is generally known that the number of bacterial species differs between when the treatment is performed smoothly and when the treatment is performed in a deteriorated state. Therefore, it is considered that the number of each bacterial species is monitored in order to perform the process smoothly. For example, as a method for determining whether or not the processing is being performed smoothly, a method has been attempted in which specific bacteria and processing performance are determined in association with each other through microscopic observation.

  Furthermore, a method has been proposed that includes a method for obtaining image information relating to the characteristics, shape, number, etc. of specific bacteria, storing it in a knowledge database, and determining the state of the activated sludge process (for example, patents). Reference 1).

In addition, in the method known in microbiology, the bacterial suspension is diluted thinly and spread on an agar medium, and each individual is cultured in a sufficiently spatially separated state, so that the bacteria propagate. The population (colony) is counted, and the treatment performance is judged from the ratio of the number of colonies of each bacterial species.
JP-A-1-31539

  However, in a method for determining specific bacteria and treatment performance in association with each other by microscopic observation, generally activated sludge is sampled from a water treatment tank, and an operator observes the bacteria using a microscope. These are all manual operations, take time, and require specialized knowledge and skill. Therefore, determination by microscopic observation is not widespread despite its significance being recognized.

  There is also a method of obtaining image processing and using it for observing bacteria, but now it is a stage where the length of filamentous microorganisms is measured and the area and number of activated sludge flocs are measured. Application to the identification of protozoa that change or bacteria with a size of about 1 micron has not been put to practical use.

  Furthermore, in the method of calculating the ratio of the number of colonies coming out from the bacterial suspension sprinkled on the agar medium, the culture takes time in months and only those that can be cultured are counted, or the type of agar medium In addition, since completely different values appear at the timing of counting the colony number, there is a problem that the absolute value of the number of each bacterial species in the bacterial suspension cannot be obtained accurately. Therefore, it cannot be a management index for the daily water treatment process, and the ratio of the number of colonies of each bacterial species is the exact ratio of the number of bacteria at that time, that is, the exact number of each bacterial species. Not represented.

  That is, a water treatment process in which a plurality of bacteria are present in a water treatment tank has been treated like a kind of black box because it is difficult to analyze the type and activity of the bacteria.

  On the other hand, a nitrification denitrification method is known as a method for removing nitrogen components. The nitrification denitrification method uses bacteria contained in activated sludge to oxidize ammonia nitrogen from wastewater through nitrite nitrogen to nitrate nitrogen, then reduce from nitrate nitrogen to nitrite nitrogen to nitrogen molecules, and then In this method, nitrogen gas is diffused into the atmosphere. A reaction that oxidizes ammonia nitrogen to nitrate nitrogen is called nitrification, and a reaction that reduces nitrate nitrogen to nitrogen molecules is called denitrification. That is, nitrification and denitrification are combined to form a nitrification denitrification method.

  The nitrification denitrification method is not a reaction that can be performed by a single bacterium, but a plurality of bacteria present in the activated sludge. First, regarding nitrification, it is known that there are ammonia oxidizing bacteria that oxidize from ammonia nitrogen to nitrite nitrogen and nitrite oxidizing bacteria that oxidize from nitrite nitrogen to nitrate nitrogen. Examples of ammonia oxidizing bacteria include Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosobolus and the like. Examples of nitrite oxidizing bacteria include Nitrobacter, Nitrococcus, Nitrospira and the like.

  Regarding denitrification, the existence of various denitrifying bacteria that reduce nitrate nitrogen or nitrite nitrogen to nitrogen molecules is known. Nitrate-reducing bacteria that reduce from nitrate nitrogen to nitrite nitrogen, nitrite-reducing bacteria that reduce from nitrite nitrogen to nitric oxide, bacteria that reduce from nitric oxide to nitrous oxide, from nitrous oxide to nitrogen molecule Examples include nitrous oxide-reducing bacteria that reduce. Examples of nitrate-reducing bacteria include Azotobacter, Bacillus, Paracoccus, Pseudomonas and the like. Examples of nitrite-reducing bacteria include Paracoccus and Pseudomonas. Examples of nitrous oxide-reducing bacteria include Corynebacterium, Pseudomonas and the like.

  Therefore, in view of the above points, the present invention specifies the indicator bacteria that serve as an indicator of the treatment performance of the water treatment process, so that no delay in countermeasures occurs, and the treatment performance is not dependent on the ability of the operator. It aims at providing the water treatment management method which can be maintained.

  In particular, in view of the above points, the present invention is directed to a group consisting of ammonia oxidizing bacteria, nitrite oxidizing bacteria, nitrate reducing bacteria, nitrite reducing bacteria, and nitrous oxide reducing bacteria. Therefore, it is an object of the present invention to provide a water treatment management method capable of maintaining the treatment performance without depending on the ability of the operator without causing a delay in measures.

  The present invention is a water treatment management method for managing the treatment performance of a water treatment process, wherein the water treatment process uses a plurality of types of bacteria and is treated from a treated water supplied to a water treatment tank. A selection step of selecting an indicator bacterium as an indicator of treatment performance from the plurality of types of bacteria, a measurement step of measuring the number of indicator bacteria in the water treatment tank, and the water treatment And a holding step of holding a predetermined number or more of indicator bacteria in the tank (Claim 1).

  According to the water treatment management method of the present invention, by identifying the indicator bacteria that serve as an indicator of the treatment performance of the water treatment process, it is only necessary to measure the identified indicator bacteria thereafter, so that the treatment performance can be grasped quickly. It becomes possible.

  In addition, since only the specified indicator bacteria need to be held at a predetermined number or more, when the number of indicator bacteria is less than the predetermined number, a substrate suitable for the indicator bacteria is added, pH, temperature, redox potential (ORP) By controlling the above, it is possible to maintain the processing performance without causing a delay in measures.

  Furthermore, it becomes possible to objectively manage the processing performance without depending on the operator's ability and subjective judgment.

  Here, “substance to be treated” refers to a nitrogen component, a specific chemical substance, or the like.

  The present invention is a water treatment management method for managing the treatment performance of a water treatment process, wherein the water treatment process uses a plurality of types of bacteria to remove nitrogen components from water to be treated supplied to a water treatment tank. A selection step of selecting an indicator bacterium to be removed and serving as an indicator of treatment performance from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria; It includes a measuring step of measuring the number of indicator bacteria in the water treatment tank and a holding step of holding a predetermined number or more of indicator bacteria in the water treatment tank (claim 2).

  According to the water treatment management method of the present invention, the indicator bacteria that serve as an indicator of the treatment performance of the water treatment process are the group consisting of ammonia oxidizing bacteria, nitrite oxidizing bacteria, nitrate reducing bacteria, nitrite reducing bacteria, and nitrous oxide reducing bacteria. Since it is sufficient to measure only the specified indicator bacteria after that, it becomes possible to quickly grasp the processing performance.

  In addition, since the indicator bacteria can be identified in 1 to 2 days, it can be quickly reflected in operation management.

  In addition, since only the specified indicator bacteria need be retained at a predetermined number or more, when the number of indicator bacteria is less than the predetermined number, a substrate suitable for the indicator bacteria is added, and pH, temperature, redox potential, etc. are controlled. By doing so, it is possible to maintain the processing performance without causing a delay in measures.

  Furthermore, it is possible to manage the processing performance with high accuracy and objectively without depending on the ability and subjective judgment of the operator.

  Here, the “nitrogen component” refers to a nitrogen atom such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen or the like.

  Further, the present invention relates to the ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria based on the relationship between the number of single bacteria and the treatment performance. It is preferable to select (Claim 3).

  According to the water treatment management method of the present invention, the number of single bacteria and treatment of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria using treated water. By creating something that indicates the relationship with the performance, it is possible to grasp the reaction that is important in the processing performance, so it is possible to accurately grasp the processing performance.

  At this time, it is preferable to create all the five types of bacteria that show the relationship between the number of single bacteria and the processing performance, but it is also possible to create them with at least one type of bacteria.

  Here, the “single bacterium” refers to a kind of bacteria selected from the group consisting of ammonia oxidizing bacteria, nitrite oxidizing bacteria, nitrate reducing bacteria, nitrite reducing bacteria, and nitrous oxide reducing bacteria. In addition, even if it is a kind of bacteria selected from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria, a plurality of types of bacteria may exist. . For example, when a nitrite-reducing bacterium is a single bacterium, a plurality of types of bacteria such as Paracoccus and Pseudomonas that are nitrite-reducing bacteria are used as a single bacterium.

  In the present invention, it is preferable to use a quantitative PCR method in the measurement step (claim 4). Examples of the quantitative PCR method include C-PCR method, real-time PCR method, MPN-PCR method and the like.

  According to the water treatment management method of the present invention, since it can be determined by the quantitative PCR method, the number of indicator bacteria in the water treatment tank can be measured more quickly and accurately.

  And as for this invention, it is preferable that the said to-be-processed water is the waste_water | drain from a thermal power station (Claim 5). Furthermore, in the present invention, it is preferable that the indicator bacterium is a nitrite-reducing bacterium (claim 6). This is because the reaction controlled by nitrite-reducing bacteria in effluent from thermal power plants is likely to be rate-limiting in the nitrification denitrification method.

  According to the water treatment management method of the present invention, by identifying the indicator bacteria that serve as an indicator of the treatment performance of the water treatment process, it is only necessary to measure the identified indicator bacteria thereafter, so that the treatment performance can be grasped quickly. It becomes possible.

  In addition, since only the specified indicator bacteria need be retained at a predetermined number or more, when the number of indicator bacteria is less than the predetermined number, a substrate suitable for the indicator bacteria is added, and pH, temperature, redox potential, etc. are controlled. By doing so, it is possible to maintain the processing performance without causing a delay in measures.

  Furthermore, it becomes possible to objectively manage the processing performance without depending on the operator's ability and subjective judgment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following unless it exceeds the gist thereof.

  FIG. 1 is a schematic configuration diagram of a water treatment process for managing treatment performance by a water treatment management method according to the present invention. The water treatment process includes a nitrification tank 2, a denitrification tank 4, a re-aeration tank 6, and a precipitation tank 8 in this order.

  In the present invention, waste water (treated water) containing a nitrogen component is introduced into the connecting pipe 1 and first supplied to the nitrification tank 2. In the nitrification tank 2, ammonia nitrogen is oxidized to nitrite nitrogen and a part or all of nitrite nitrogen is oxidized to nitrate nitrogen by activated sludge containing ammonia oxidizing bacteria, nitrite oxidizing bacteria, and the like.

  Subsequently, the water treated in the nitrification tank 2 is fed to the denitrification tank 4 through the communication pipe 3. In the denitrification tank 4, nitrite nitrogen and / or nitrate nitrogen generated in the nitrification tank 2 is reduced to nitrogen gas by activated sludge containing nitrate reducing bacteria, nitrite reducing bacteria, nitrous oxide reducing bacteria and the like. At this time, nitrogen gas is diffused into the atmosphere.

  Subsequently, the treated water treated in the denitrification tank 4 is supplied to the re-aeration tank 6 through the communication pipe 5. In the re-aeration tank 6, organic substances are decomposed and removed by treatment under aerobic conditions.

  Further, the water treated in the re-aeration tank 6 is fed to the precipitation tank 8 through the communication pipe 7. In the precipitation tank 8, the liquid is separated into a separated liquid and a precipitated sludge. Thereafter, the separation liquid is taken out through the connecting tube 9. On the other hand, a part of the precipitated sludge is returned to the nitrification tank 2 as return sludge. Further, the remaining part of the precipitated sludge is discharged out of the water treatment process as excess sludge, for example, and appropriately treated.

  Examples of the wastewater include wastewater from thermal power plants, wastewater from steelworks, wastewater from food plants, wastewater from paper pulp plants, wastewater from chemical plants, and domestic wastewater such as sewage treatment. Although it is mentioned, the drainage from a thermal power plant is preferable. That is, it becomes more effective for the waste water whose total nitrogen concentration is 20 mg / L or more and 100 mg / L or less.

  Here, FIG. 2 is a flowchart showing an example of a routine of the water treatment management method of the present invention. The water treatment management method of the present invention includes a preparation stage including a creation process and an execution stage including a selection process, a measurement process, and a holding process. In the water treatment management method of the present invention, the preparation stage is prepared for managing the treatment performance, and the execution stage is for actually managing the treatment performance.

  First, a creation process is performed (step S1). In the preparation process, using the above wastewater, a correlation formula showing the relationship between the number of single bacteria and treatment performance for ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria To determine the coefficient of determination. The creation process will be described in detail later.

  Next, a selection process is performed (step S2). In the selection step, an indicator bacterium that serves as an indicator of processing performance is selected from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria based on the determination coefficient. The selection process will be described in detail later.

  Next, a measurement process is performed (step S3). In the measurement step, the number of indicator bacteria in the water treatment tank is measured. At this time, it is preferable to use a quantitative PCR method such as a C-PCR method, a real-time PCR method, or an MPN-PCR method, and the C-PCR method is more preferable in that a result can be obtained quickly and more accurately. In addition, about a measurement process, the case where C-PCR method is used later is explained in full detail.

  Next, a holding process is performed (step S4). In the holding step, a predetermined number or more of indicator bacteria are held in the water treatment tank. The holding process will be described in detail later.

  Next, it is determined whether or not to continue managing the processing performance (step S5). When it is determined that the management of the processing performance is to be continued, the measurement process is performed again (step S3). That is, the processes of steps S3 to S4 described above are repeatedly executed. By repeatedly executing the process in this manner, the state in the water treatment tank is again determined, that is, the processing performance is managed. In addition, when performing a measurement process again, it is preferable to carry out on the day different from the last day.

  On the other hand, when it is determined in step S5 that the management of the processing performance is not continued, this routine is ended.

  Next, a creation process subroutine for creating a correlation equation showing the relationship between the number of nitrite-reducing bacteria and the treatment performance performed in step S1 shown in FIG. 2 and calculating a determination coefficient will be described with reference to FIG. . In the water treatment management method of the present invention, the correlation showing the relationship between the number of single bacteria and the treatment performance for ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria. The formula is created and the coefficient of determination is calculated by this, but the correlation process showing the relationship between the number of nitrite-reducing bacteria and the processing performance is created, and the creation process for calculating the coefficient of determination by this is mainly described. .

(1) Creation process First, activated sludge is sampled from the denitrification tank 4 (step S10).

  Next, the total DNA of a plurality of types of bacteria contained in the activated sludge is extracted (step S11). Furthermore, it is preferable to purify the total DNA after decomposing the mixed RNA. Examples of the method for extracting total DNA include a conventional method described in a literature such as Current Protocol in Molecularbiology or a method using a commercially available DNA extraction kit.

  Next, a known number of competitive DNAs are added to the extracted total DNA, and the target DNA fragment and the competitive DNA fragment present in the nitrite-reducing bacteria are amplified by the DNA replication enzyme chain reaction (PCR method) (step S12). ). At this time, in order to measure the number of nitrite-reducing bacteria in the denitrification tank 4 to be described later (step S16), the extracted total DNA is divided into several pieces, and a different number of competitive DNAs are added to each to perform PCR. Do the law. Examples of the PCR method include a method of adding primers, enzymes (Taq polymerase), dNTPs, salts and the like to the extracted total DNA and competitive DNA. As a primer, a DNA fragment having a base sequence designed for detecting nitrite-reducing bacteria, that is, specifically binding only to DNA of nitrite-reducing bacteria and competitive DNA, Those that do not bind to bacterial DNA other than competitive DNA are selected.

  The reaction temperature in the PCR method is preferably set to a value that takes into account the Tm value of the primer. Furthermore, the number of cycles in the PCR method is preferably 15 cycles or more and 50 cycles or less.

  Next, for each, the obtained target DNA fragment and competitive DNA fragment are separated (step S13). Examples of the method for separating the target DNA fragment and the competitive DNA fragment include agarose gel electrophoresis and polyacrylamide gel electrophoresis. Agarose gel electrophoresis is convenient and preferable. For example, using agarose gel of 1% or more and 3% or less and performing at 100 V for about 30 minutes at room temperature can be mentioned.

  Next, a dye that specifically binds to the DNA fragment and emits fluorescence, such as ethidium bromide, SYBR Gold, SYBR Green I, or the like is added (step S14).

  Next, the fluorescence intensity of the band corresponding to the target DNA fragment and the competitive DNA fragment emitted when the excitation light of a predetermined wavelength is irradiated by a gel documentation system or the like is measured (step S15). FIG. 4 is an example of an agarose gel electrophoresis photograph of the target DNA fragment and the competitive DNA fragment. Since the target DNA fragment and the competitive DNA fragment are different in the number of base pairs, they are divided into positions corresponding to the number of base pairs. Each band corresponding to each has a fluorescence intensity corresponding to the number. Furthermore, for comparison, a sample containing a different number of competitive DNAs is run on a single agarose gel.

  Next, the number of nitrite-reducing bacteria in the denitrification tank 4 is measured based on the relationship between the ratio of the fluorescence intensity of the band corresponding to the target DNA fragment and the competitive DNA fragment and the number of mixed competitive DNAs (step) S16). For example, the relationship between the ratio of the fluorescence intensity of the band corresponding to the target DNA fragment and the competitive DNA fragment and the number of mixed competitive DNAs corresponds to the fluorescence intensity T of the band corresponding to the target DNA fragment and the competitive DNA fragment. A graph or the like is created with the logarithm of the ratio to the fluorescence intensity C of the band to be used as the horizontal axis and the logarithm of the number N of competitive DNAs mixed as the vertical axis (see FIG. 5). And it approximates with a linear function Y = aX + b. As a result, the point where the fluorescence intensity of the band corresponding to the target DNA fragment becomes equal to the fluorescence intensity of the band corresponding to the competitive DNA, that is, the intersection of the line where log (T / C) is 0 and the approximate expression By reading, the number of nitrite-reducing bacteria contained in the collected activated sludge is obtained, and the number of nitrite-reducing bacteria in the denitrification tank 4 is obtained.

  Next, the total nitrogen per unit time in the waste water and the total nitrogen concentration in the separation liquid are measured (step S17). In order to measure the total nitrogen per unit time in the waste water, for example, the waste water is collected from the connecting pipe 1, the total nitrogen concentration TN in the waste water is measured, and the amount of waste water per unit time is further measured. On the other hand, in order to measure the total nitrogen concentration TN in the separation liquid, for example, the separation liquid is collected from the communication tube 9. Here, the total nitrogen concentration TN means the concentration of all nitrogen atoms such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and the like.

  Examples of the method for measuring total nitrogen include the summation method, Kjeldahl nitrogen method, reductive distillation Kjeldahl method, ultraviolet absorption photometry method, etc. (see “Sewage Test Method”, Vol. 1, 1997 edition, Japan Sewerage Association) ).

  Next, it is determined whether or not the data indicating the relationship between the number of nitrite-reducing bacteria and the processing performance is sufficient (step S18). If it is determined that there is not enough data to create a correlation equation indicating the relationship between the number of nitrite-reducing bacteria and the treatment performance, activated sludge is again collected from the denitrification tank 4 (step S10). That is, the processes of steps S10 to S17 described above are repeatedly executed. By repeatedly executing the processing in this way, the number of data indicating the relationship between the number of nitrite-reducing bacteria and the processing performance is increased. In addition, when collecting activated sludge again from the inside of the denitrification tank 4, it is preferable to carry out on the day different from the last day.

On the other hand, when it is determined in step S18 that the data indicating the relationship between the number of nitrite-reducing bacteria and the processing performance is sufficient, a correlation equation indicating the relationship between the number of nitrite-reducing bacteria and the processing performance is created ( Step S19). For example, as a correlation equation showing the relationship between the number of nitrite-reducing bacteria and treatment performance, the nitrogen load per nitrite-reducing bacterium (total nitrogen per unit time in wastewater / number of nitrite-reducing bacteria) A graph or the like having the vertical axis and the total nitrogen concentration TN in the separation liquid as the vertical axis is created (see FIG. 6A). Then, the correlation function is obtained by approximating with the exponential function Y = ae ^bX .

Next, a determination coefficient R ² is calculated based on the correlation equation (step S20).

  In FIG. 3, the correlation equation indicating the relationship between the number of nitrite-reducing bacteria and the treatment performance is created and the process of calculating the determination coefficient has been described. However, the same applies to nitrate-reducing bacteria and nitrous oxide-reducing bacteria. (See FIG. 6C). Further, ammonia oxidizing bacteria and nitrite oxidizing bacteria are similarly processed except that the place where the activated sludge is collected in step S10 is changed from the denitrification tank 4 to the nitrification tank 2 (see FIG. 6B). . Thus, the water treatment management method of the present invention shows the relationship between the number of single bacteria and the treatment performance for ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria. It is preferable to create a correlation formula and thereby calculate the coefficient of determination.

  Note that FIG. 3 shows a case where only a correlation equation indicating the relationship between the number of nitrite-reducing bacteria and the treatment performance is created. The target DNA fragment and the competitive DNA fragment of the present invention are amplified by the PCR method, and all of the target DNA fragment and the competitive DNA fragment are separated, so that nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria are isolated. A correlation equation indicating the relationship between the number of one and the processing performance may be created at the same time.

(2) Selection Step Next, an indicator bacterium that serves as an index of processing performance based on the coefficient of determination performed in step S2 shown in FIG. 2 is selected from ammonia oxidizing bacteria, nitrite oxidizing bacteria, nitrate reducing bacteria, nitrite reducing bacteria, and An example of the selection process for selecting from the group consisting of nitrous oxide-reducing bacteria will be described.

Based on the determination coefficient of each bacterium prepared in the above-described preparation process, the one having the highest determination coefficient R ² is selected, and the indicator bacteria serving as the processing performance index are selected from ammonia oxidizing bacteria and nitrite oxidation. Selected from the group consisting of bacteria, nitrate reducing bacteria, nitrite reducing bacteria and nitrous oxide reducing bacteria.

  In the following, a case where nitrite-reducing bacteria are selected as indicator bacteria will be described. In addition, after identifying the indicator bacteria that are indicators of treatment performance from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria, in order to manage the treatment performance Therefore, it is only necessary to measure the number of the specified indicator bacteria.

(3) Measurement Step Next, a measurement step subroutine for measuring the number of nitrite-reducing bacteria in the denitrification tank 4 performed in step S3 shown in FIG. 2 will be described using the flowchart shown in FIG. First, activated sludge is collected from the denitrification tank 4 (step S21).

  Next, the total DNA of a plurality of types of bacteria contained in the activated sludge is extracted (step S22). Examples of the method for extracting DNA include the same methods as described above.

  Next, a known number of competitive DNA is added to the extracted total DNA, and the indicator DNA fragment and the competitive DNA fragment present in the nitrite-reducing bacteria are amplified by the PCR method (step S23). At this time, the extracted total DNA is divided into several pieces, and a different number of competitive DNAs are added to each to perform PCR. Examples of the PCR method include a method of adding primers, enzymes (Taq polymerase), dNTPs, salts and the like to the extracted total DNA and competitive DNA. As a primer, a DNA fragment having a base sequence designed for detecting nitrite-reducing bacteria, that is, specifically binding only to DNA of nitrite-reducing bacteria and competitive DNA, Those that do not bind to bacterial DNA other than competitive DNA are selected.

  The reaction temperature in the PCR method and the number of cycles in the PCR method are preferably the same as those described above.

  Next, for each, the obtained indicator DNA fragment and competitive DNA fragment are separated (step S24). Examples of the method for separating the indicator DNA fragment and the competitive DNA fragment include the same methods as described above.

  Next, a dye that specifically binds to the DNA fragment and emits fluorescence, such as ethidium bromide, SYBR Gold, SYBR Green I, or the like is added (step S25).

  Next, the fluorescence intensity of the band corresponding to the indicator DNA fragment and the competitive DNA fragment emitted when the excitation light of a predetermined wavelength is irradiated by a gel documentation system or the like is measured (step S26).

  Next, the number of nitrite-reducing bacteria in the denitrification tank 4 is measured based on the relationship between the ratio of the fluorescence intensity of the bands corresponding to the indicator DNA fragment and the competitive DNA fragment and the number of mixed competitive DNAs (step) S27). For example, as the relationship between the ratio of the fluorescence intensity of the band corresponding to the indicator DNA fragment and the competitive DNA fragment and the number of the competitive DNAs mixed, the ratio of the fluorescence intensity of the band corresponding to the indicator DNA fragment and the competitive DNA fragment A graph or the like is created with the logarithm as the horizontal axis and the logarithm of the number of mixed competitive DNAs as the vertical axis. And it approximates with a linear function Y = aX + b. As a result, the nitrite reduction contained in the collected activated sludge was obtained by reading the intersection of the line with the logarithm of the ratio of the fluorescence intensity of the band corresponding to the indicator DNA fragment and the competitive DNA fragment being zero and the approximate expression. The number of bacteria is obtained, and the number of nitrite-reducing bacteria in the denitrification tank 4 is obtained.

  Next, the total nitrogen per unit time in the waste water is measured (step S28). In order to measure the total nitrogen per unit time in the waste water, for example, the waste water is collected from the connecting pipe 1, the total nitrogen concentration TN in the waste water is measured, and the amount of waste water per unit time is further measured.

(4) Holding Step Next, an example of a holding step for holding a predetermined number or more of nitrite-reducing bacteria in the denitrification tank 4 performed in step S4 shown in FIG. 2 will be described.

  When the number of nitrite-reducing bacteria is less than a predetermined number (for example, the nitrogen load per nitrite-reducing bacteria is larger than a predetermined number), a substrate suitable for nitrite-reducing bacteria is added to the denitrification tank 4 or denitration is performed. The pH, temperature, oxidation-reduction potential, etc. in the nitrogen tank 4 are controlled. On the other hand, when the number of nitrite-reducing bacteria is not less than a predetermined number (for example, the nitrogen load per nitrite-reducing bacteria is not more than a predetermined number), nothing is required. By measuring the number of nitrite-reducing bacteria in this way, it is possible to maintain the processing performance without causing a delay in measures.

  In addition, as described with reference to FIG. 1, the water treatment management method of the present invention can be used in a configuration including the nitrification tank 2, the denitrification tank 4, the re-aeration tank 6, and the precipitation tank 8 in this order. Furthermore, in the present invention, as shown in FIG. 8, a denitrification tank 21, a nitrification tank 22, and a precipitation tank 23 are provided in this order, and the nitrification liquid treated in the nitrification tank 22 is used in a configuration that can be circulated to the denitrification tank 21. It is also possible.

  When used in such a configuration, when the nitrite-reducing bacteria in the denitrification 21 are selected as indicator bacteria, the number of nitrite-reducing bacteria in the denitrification tank 21 is measured to determine a predetermined value in the denitrification tank 21. It will retain more than a few nitrite-reducing bacteria.

  Further, as shown in FIG. 9, the water treatment management method of the present invention includes a denitrification tank 31, a nitrification tank 32, a denitrification tank 33, a nitrification tank 34, and a precipitation tank 35 in this order, and was treated in the nitrification tank 34. It is also possible to use the structure in which the nitrification liquid can be circulated to the denitrification tank 33 and the waste water can be supplied to the denitrification tank 31 and the denitrification tank 33.

  When used in such a configuration, when the nitrite-reducing bacteria in the denitrification tank 31 and the denitrification tank 33 are selected as indicator bacteria, the number of nitrite-reducing bacteria in the denitrification tank 31 and the denitrification tank 33 is measured. Thus, a predetermined number or more of nitrite-reducing bacteria are retained in the denitrification tank 31 and the denitrification tank 33.

  In addition, as a water treatment tank such as a denitrification tank or a nitrification tank, for example, an activated sludge treatment apparatus that floats activated sludge containing bacteria in the water treatment tank, a fluidized bed type using a carrier to which activated sludge containing bacteria is attached. A processing apparatus, a fixed bed type processing apparatus, etc. are mentioned. Therefore, in the case of the above activated sludge treatment apparatus, a constant volume of sample is taken from the water treatment tank, and then converted into the entire sample volume in the water treatment tank, thereby grasping the state in the water treatment tank. It will be possible. In the case of the above fluidized bed type processing apparatus and fixed bed type processing apparatus, a fixed number of carriers or sludge from a certain surface area is collected from the water treatment tank, and then converted into the total number of carriers in the treatment tank. By doing so, the state in the water treatment tank can be grasped.

  In a water treatment process having a nitrification tank 2, a denitrification tank 4, a re-aeration tank 6, and a precipitation tank 8 as shown in FIG. 1, nitrogen components are removed from waste water from a thermal power plant, The water treatment process taken out as (TN: 2.0 mg / L or less) was performed. In addition, the denitrification tank 4 is an activated sludge treatment apparatus, and the effective volume in the denitrification tank 4 was 400,000 L.

(1) Preparation process First, 1 mL of the activated sludge and waste water mixture was collected from the denitrification tank 4. Next, the activated sludge in the mixture was separated by centrifugation to obtain activated sludge. Then, total DNA of a plurality of types of bacteria contained in the activated sludge was extracted using FastDNA SPIN kit for Soil (manufactured by Qbiogene, Inc.) according to the method recommended by the manufacturer, and 11400 ng of total DNA was obtained.

Next, a known number of competitive DNAs were added to the extracted total DNA using a competitive DNA Construction Kit (manufactured by Takara Bio Inc.) according to the method recommended by the manufacturer. At this time, five samples with 10 ng of total extracted DNA were prepared, and competitive with 1.25 × 10 ³ , 2.5 × 10 ³ , 5 × 10 ³ , 1 × 10 ⁴ , and 2 × 10 ⁴ copies respectively. 1.0 μL of DNA was added. In addition, 5.0 μL of 10 × PCR Buffer (Qiagen), 10.0 μL of 5 × Q solution (Qiagen), 4.0 μL of 10 mM dNTPs (Applied Biosystems Japan), 2.0 μL of 25 mM MgCl ₂ , 0.3 μL of 0.3 unit Taq polymerase (manufactured by Qiagen) and 0.5 μL of each primer were added, and a reaction solution with a total volume of 50 μL was obtained using sterile water (manufactured by Eppendorf).

  Each primer used was a DNA fragment described below having a base sequence designed to detect the target nitrite-reducing bacteria (nir S) (reference: G. Braker, A. Fesefeldt, and KP. Witzel, 1998 Appl. Environ. Microbiol. 64, 3769-3775.).

nirS1F: CCTA (C / T) TGGCCGCC (A / G) CA (A / G) T (SEQ ID NO: 1)
nirS6R: CGTTGAACTT (A / G) CCGGT (SEQ ID NO: 2)
And PCR method was implemented on the conditions shown in Table 1 using the obtained reaction liquid.

次に、ＰＣＲ法で増幅させた目的ＤＮＡ断片及び競合的ＤＮＡ断片10μLに1μLのloading dye（東洋紡績株式会社製）を添加して、常法にしたがい、室温で、１００Ｖ、３０分で２％アガロースゲルを用いて電気泳動を行った。

Next, 1 μL of loading dye (manufactured by Toyobo Co., Ltd.) is added to 10 μL of the target DNA fragment and competitive DNA fragment amplified by the PCR method, and 2% at 100 V for 30 minutes at room temperature according to a conventional method. Electrophoresis was performed using an agarose gel.

  Next, ethidium bromide staining was performed, and the fluorescence intensity of the band corresponding to the target DNA fragment and the competitive DNA fragment was measured by electrophoresis gel imaging / analysis method 1D Image Analysis Software (Kodak) (see FIG. 4).

  Thus, the horizontal axis represents the logarithm of the ratio of the fluorescence intensity T of the band corresponding to the target DNA fragment and the fluorescence intensity C of the band corresponding to the competitive DNA fragment, and the logarithm of the number N of mixed competitive DNAs represents the vertical axis. A graph was created. And it approximated with linear function Y = aX + b, and Y = -1.3007X + 4.0877 was obtained (refer FIG. 5).

From FIG. 5, by reading the intersection of the line where log (T / C) is 0 and the graph as 4.09, the number of nitrite-reducing bacteria contained in 10 ng of total DNA was calculated as 10 ^4.09 copies. Since the total DNA purified from 1 mL of the activated sludge and wastewater mixture was 11400 ng, the number of nitrite-reducing bacteria contained in 1 mL of the activated sludge and wastewater mixture was 10 ^4.09 × 11400/10 = 10 ^7.15. It was calculated to be copies.

Next, the total nitrogen concentration TN in the wastewater collected from the connecting pipe 1 is 40 mg / L (NH ₄ -N: 20 mg / L, NO ₂ -N: 10 mg / L, NO ₃ -N: 10 mg / L) Further, the amount of discharged water per day was measured as 1800 m ³ . On the other hand, the total nitrogen concentration TN in the separated liquid collected from the connecting tube 9 was measured as 0.9 mg / L (the amount of water per day: 1800 m ³ ).

The above-described processing was repeatedly executed at regular intervals. This produced a graph with the horizontal axis representing the nitrogen load per nitrite-reducing bacterium and the vertical axis representing the total nitrogen concentration TN in the separation liquid. Then, an approximation was made with an exponential function Y = ae ^bX to obtain a correlation equation Y = 0.5826e ^{4E + 0.7X} . Furthermore, the determination coefficient R ² was obtained as 0.7880 (see FIG. 6A).

Similarly, it performed for nitrous oxide reducing bacteria, the coefficient of determination R ² to give a 0.2136 (see Figure 6 (c)).

  Each primer used was a DNA fragment described below having a base sequence designed to detect the target nitrous oxide reducing bacterium (Nos Z) (Reference: DJScala and LJKerkhof. 1998 FEMS). Microbiology Letters 168, 61-68).

Nos1527F: CGCTGTTC (A / T / C) TCGACAG (C / T) CA (SEQ ID NO: 3)
Nos1773R: AT (A / G) TCGATCA (A / G) CTG (T / C / G) TCGTT (SEQ ID NO: 4)
Furthermore, ammonia-oxidizing bacteria were obtained in the same manner except that the place for collecting activated sludge was changed from the denitrification tank 4 to the nitrification tank 2, and a determination coefficient R ² of 2 × 10 ⁻⁹ was obtained (FIG. 6 (b)). )reference).

  Each primer used was a DNA fragment described below having a base sequence designed to detect the target bacteria, ammonia-oxidizing bacteria (amo A) (reference: JH. Rotfhauwe, KP. Witzel and W. Liesack. 1997. Appl. Environ. Microbiol. 63, 4704-4712).

amoA-1F: GGGGTTTCTACTGGTGGT (SEQ ID NO: 5)
amoA-2R: CCCCTC (G / T) G (C / G) AAAGCCTTCTTC (SEQ ID NO: 6)
(2) selection process based on the coefficient of determination of each of the bacteria that have been created in the above-described forming process, the coefficient of determination R ² has selected the most high was nitrite-reducing bacteria as the indicator bacteria.

(3) Measurement process First, 1 mL of the activated sludge and wastewater mixture was collected from the denitrification tank 4. Next, the activated sludge in the mixture was separated by centrifugation to obtain activated sludge. Then, total DNA of a plurality of types of bacteria contained in the activated sludge was extracted according to the method recommended by the manufacturer using FastDNA SPIN kit for Soil (manufactured by Qbiogene, Inc.) to obtain 12300 ng of total DNA.

Next, a known number of competitive DNAs were added to the extracted total DNA using a competitive DNA Construction Kit (manufactured by Takara Bio Inc.) according to the method recommended by the manufacturer. At this time, five samples with 10 ng of total extracted DNA were prepared, and competitive with 1.25 × 10 ³ , 2.5 × 10 ³ , 5 × 10 ³ , 1 × 10 ⁴ , and 2 × 10 ⁴ copies respectively. 1.0 μL of DNA was added. In addition, 5.0 μL 10 × PCR Buffer (Qiagen), 10.0 μL 5 × Q solution (Qiagen), 4.0 μL 10 mM dNTPs (Applied Biosystems Japan), 2.0 μL 25 mM MgCl ₂ , 0.3 μL 0.3 unit Taq polymerase (Qiagen), 0.5 μL of each primer was added, and a sterilized water (Eppendorf) was used to obtain a reaction solution with a total volume of 50 μL.

  As each primer, a DNA fragment described below having a base sequence designed to detect nitrite-reducing bacteria (nir S), which are indicator bacteria, was used.

nirS1F: CCTA (C / T) TGGCCGCC (A / G) CA (A / G) T (SEQ ID NO: 1)
nirS6R: CGTTGAACTT (A / G) CCGGT (SEQ ID NO: 2)
And PCR method was implemented on the conditions shown in Table 1 using the obtained reaction liquid.

  Next, 1 μL of loading dye (manufactured by Toyobo Co., Ltd.) is added to 10 μL of the indicator DNA fragment and competitive DNA fragment amplified by the PCR method, and 2% at 100 V for 30 minutes at room temperature according to a conventional method. Electrophoresis was performed using an agarose gel.

  Next, ethidium bromide staining was performed, and the fluorescence intensity of the bands corresponding to the indicator DNA fragment and the competitive DNA fragment was measured by electrophoresis gel imaging / analysis method 1D Image Analysis Software (Kodak).

  Thus, the horizontal axis represents the logarithm of the ratio of the fluorescence intensity T of the band corresponding to the indicator DNA fragment and the fluorescence intensity C of the band corresponding to the competitive DNA fragment, and the logarithm of the number N of mixed competitive DNAs represents the vertical axis. A graph was created. And it approximated by the linear function Y = aX + b, and Y = 1.13X + 4.18 was obtained.

The intersection between the line and the graph log (T / C) is 0 by reading the 4.18, the number of nitrite-reducing bacteria contained in the total DNA 10 ng was calculated as 10 ^4.18 copies. Since the total DNA purified from 1 mL of the activated sludge and wastewater mixture was 12300 ng, the number of nitrite-reducing bacteria contained in 1 mL of the activated sludge and wastewater mixture was 10 ^4.18 × 12300/10 = 10 ^7.27. It was calculated to be copies.

Next, the total nitrogen concentration TN in the wastewater collected from the connecting pipe 1 is 40 mg / L (NH ₄ -N: 20 mg / L, NO ₂ -N: 10 mg / L, NO ₃ -N: 10 mg / L) Further, the amount of discharged water per day was measured as 1800 m ³ .

(4) Holding step From Fig. 6 (a), in order to keep the total nitrogen concentration (TN) of the separation liquid at 2.0 mg / L or less, the nitrogen load per nitrite-reducing bacterium is set to 3.2 x 10 ^-8. Nitrite-reducing bacteria may be retained so as to be less than mg / (copies · day). Therefore, in order to manage the processing performance, a measurement process for measuring the number of nitrite-reducing bacteria was performed every 10 days. When the nitrogen load per nitrite-reducing bacterium exceeds 3.2 × 10 ^-8 mg / (copies / day), a substrate suitable for nitrite-reducing bacteria can be added, pH, temperature, redox potential, etc. Controlled. On the other hand, when the nitrogen load per nitrite-reducing bacterium was 3.2 × 10 ⁻⁸ mg / (copies · day) or less, nothing was done.

<Evaluation method>
From the beginning of managing the processing performance, the total nitrogen concentration TN in the separated liquid collected from the communication tube 9 was measured on the first, tenth, twentieth, thirty and forty days. The results are shown in Table 2.

実施例１に係る水処理管理方法によれば、水処理プロセスの処理性能の指標となる指標細菌を亜硝酸還元細菌に特定して、その後は亜硝酸還元細菌の数のみを測定することにより、オペレータの能力に依存せずに、処理性能を維持できた。

According to the water treatment management method according to Example 1, by specifying an indicator bacterium as an indicator of the treatment performance of the water treatment process as a nitrite-reducing bacterium, and then measuring only the number of nitrite-reducing bacteria, The processing performance could be maintained without depending on the operator's ability.

  In addition, the relationship between the commonly used T-N-SS load and treated water quality was low, and the treatment performance could not be managed. Similarly, the relationship between the nitrogen load per ammonia-oxidizing bacterium (Fig. 6 (b)) and the nitrogen load per nitrous oxide-reducing bacterium (Fig. 6 (c)) and the quality of treated water is low. It was not possible to manage the processing performance.

  In this way, measures are taken by identifying indicator bacteria that are indicators of treatment performance of water treatment processes from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria. The processing performance can be maintained without depending on the operator's ability and subjective judgment.

It is a schematic block diagram of the water treatment process which manages process performance with the water treatment management method which concerns on this invention. It is a flowchart which shows an example of the routine of the water treatment management method of this invention. It is a flowchart which shows the subroutine of the preparation process which produces the correlation type | formula which shows the relationship between the number of nitrite reduction bacteria, and processing performance, and calculates a determination coefficient. It is an example of the agarose gel electrophoresis photograph of the target DNA fragment and a competitive DNA fragment. A graph in which the horizontal axis represents the logarithm of the ratio of the fluorescence intensity T of the band corresponding to the target DNA fragment and the fluorescence intensity C of the band corresponding to the competitive DNA fragment, and the vertical axis represents the logarithm of the number of mixed competitive DNAs N It is. It is a graph which makes the horizontal axis | shaft the nitrogen load per bacterium, and makes the vertical axis | shaft the total nitrogen concentration TN in a separation liquid. It is a flowchart which shows the subroutine of the measurement process which measures the number of nitrite reduction bacteria in a denitrification tank. It is a schematic block diagram of the other water treatment process which manages process performance with the water treatment management method which concerns on this invention. It is a schematic block diagram of the other water treatment process which manages process performance with the water treatment management method which concerns on this invention.

Explanation of symbols

1, 3, 5, 7, 9: Communication pipe 2, 22, 32, 34: Nitrification tank 4, 21, 31, 33: Denitrification tank 6: Re-aeration tank 8, 23, 35: Precipitation tank

Claims (6)

A water treatment management method for managing the treatment performance of a water treatment process,
The water treatment process uses a plurality of types of bacteria to remove a substance to be treated from water to be treated supplied to a water treatment tank,
A selection step of selecting an indicator bacterium serving as an indicator of treatment performance from the plurality of types of bacteria;
A measuring step of measuring the number of indicator bacteria in the water treatment tank;
And a holding step of holding a predetermined number or more of indicator bacteria in the water treatment tank. A water treatment management method for managing the treatment performance of a water treatment process,
The water treatment process is to remove nitrogen components from the treated water supplied to the water treatment tank using a plurality of types of bacteria.
A selection step of selecting an indicator bacterium serving as an indicator of treatment performance from the group consisting of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria;
A measuring step of measuring the number of indicator bacteria in the water treatment tank;
And a holding step of holding a predetermined number or more of indicator bacteria in the water treatment tank.   The indicator bacteria are selected based on the relationship between the number of single bacteria and treatment performance for ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, nitrate-reducing bacteria, nitrite-reducing bacteria, and nitrous oxide-reducing bacteria. Or the water treatment management method of 2.   The water treatment management method according to any one of claims 1 to 3, wherein a quantitative PCR method is used in the measurement step.   The water treatment management method according to any one of claims 1 to 4, wherein the water to be treated is drainage from a thermal power plant. The water treatment management method according to any one of claims 1 to 5, wherein the indicator bacterium is a nitrite-reducing bacterium.

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