JP4830307B2 - Method and apparatus for processing soluble organic substance-containing liquid - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is a soluble organic substance that can be suitably used for treating a liquid containing a soluble organic substance, such as industrial waste water and domestic waste water containing polysaccharides discharged from food factories, etc., by the membrane separation activated sludge method. The present invention relates to a processing method and a processing apparatus for a contained liquid.

  As a treatment method applied to the treatment of a soluble organic substance-containing liquid such as waste water, first, a conventional activated sludge method is exemplified. However, when activated sludge composed of microorganisms and micro-animals decomposes organic matter, living organisms grow in the process, increasing activated sludge. This sludge is subjected to solid-liquid separation in a sedimentation tank or the like provided at a later stage, and a part thereof is returned to the biological treatment tank, but a part needs to be treated as surplus sludge. This surplus sludge is being reused, but most of it is still industrial waste and is disposed of in landfills after pretreatment such as dehydration and incineration. However, dehydration requires a large amount of power for dehydration and a dryer, and incineration requires a large amount of heat energy. In addition, landfill disposal sites are becoming tighter and regulations are being strengthened, resulting in a surge in disposal costs and a major environmental problem. The development of an effective volume reduction method for excess sludge has become an urgent issue.

As an example of this solution, there has been proposed a method in which a membrane separation device is provided in an aeration tank containing activated sludge, and waste water is decomposed aerobically with activated sludge and solid-liquid separation is performed with the membrane separation device. According to such a membrane separation activated sludge method, the sludge concentration is increased by retaining activated sludge by membrane separation, thereby reducing the amount of organic matter (sludge load) serving as a yield per microorganism. By reducing the sludge load, the self-degradation of microorganisms is promoted, and the energy that the microorganisms direct to growth is insufficient, resulting in the effect of reducing the generation of excess sludge.
However, in the case where the discharge of excess sludge is a more severe problem, there may be a problem that even if the membrane-separated activated sludge method is used, the excess sludge is generated even though it is less than the simple activated sludge method. is there.

  As a means to solve this problem, the membrane separation activated sludge method utilizes the fact that the generation of excess sludge is reduced by keeping the sludge load low as described above, and the sludge is compared with the conventional membrane separation activated sludge method. It is possible to further reduce the amount of extraction, lower the sludge load to less than 0.15 kg-BOD / kg-VSS / day, and reduce the amount of surplus sludge or prevent the generation of wastewater, and construct a treatment system with good treatment water quality. Sex is conceivable. If this can be realized, a treatment system having an outstanding advantage in terms of generation of surplus sludge, which is one of the major problems of the conventional membrane separation activated sludge method, can be established. However, if such sludge extraction is suppressed and operation with a low sludge load is continued, troubles with membrane permeability failure, foaming, scum, viscosity increase, etc. often occur and stable operation cannot be performed. The cause of such trouble is completely unknown.

  On the other hand, various methods for predicting and grasping instability have been proposed in biological treatment of dissolved organic matter-containing liquids such as the activated sludge method. For example, dissolved oxygen, redox potential, pH fluctuation, etc. Monitoring methods are known. Particularly in recent years, a technique for monitoring the growth of useful microorganisms and helping to control the growth has been proposed (Patent Document 1). Similarly, a technique for monitoring the growth of trouble-causing microorganisms has also been proposed. For example, filamentous bacteria (“Eikel boom type”), which is one of the causes of sedimentation failure in the activated sludge process (filamentous bulking). A method of monitoring 021N (Eikeboom Type 021N) bacteria) has been proposed (Patent Document 2).

  However, such conventional methods are not applicable to all biological treatment methods of liquids containing soluble organic substances, and are often not suitable particularly in the membrane separation activated sludge method. This is because the activated sludge method is generally a treatment method including the method described in Patent Document 2, and therefore, it is important to focus on countermeasures against sedimentation defects such as a decrease in the specific gravity of sludge and a decrease in compactness. This is because, unlike the activated sludge method, other factors such as poor membrane water permeability, foaming, scum generation, and increased viscosity become major problems in the membrane separation activated sludge method. Nevertheless, the instability prediction and grasping method and its control method appropriate for the membrane separation activated sludge method have not been sufficiently established.

  On the other hand, not only in the case of operation with low sludge load by suppressing the above sludge extraction, but also as a method of avoiding problems with membrane permeability failure, foaming, scum generation, viscosity increase etc. in conventional membrane separation activated sludge method Several techniques have been devised. For example, Patent Literature 1 and Patent Literature 2 disclose a method of performing operation control based on the viscosity measurement result of the sludge mixed liquid. However, in the methods described in these methods, the operating conditions are controlled after the viscosity has increased, that is, the method is to be dealt with after actually affecting the membrane permeability. However, a method for detecting the occurrence of trouble at an earlier stage is desired. Further, Patent Document 3 describes a method for preventing deterioration of membrane permeability by performing temperature control with multiple stages of biological treatment steps during operation with a low sludge concentration and an increased sludge load. However, this cannot make use of the above-mentioned advantages inherent in the membrane separation activated sludge method, and is not a fundamental solution.

  On the other hand, the present inventors have proposed an operation method in which treatment is carried out while monitoring the state of the bacteria of the Streptococcus strain group in the membrane separation activated sludge method (Patent Document 4). With this method, it is possible to monitor specific microorganisms that cause the above troubles, so the accuracy is high, and the trouble is caused regardless of whether or not the Fructobacillus strain bacteria are dispersed in the sludge mixture. Can be predicted and detected. However, even with this method of the present inventors, when troubles are caused by microorganisms other than the Fructobacillus strains, it is insufficient to predict and detect the occurrence of troubles.

Under these circumstances, in the membrane separation activated sludge method, especially in the membrane separation activated sludge method, in which the sludge load is further reduced compared to the conventional membrane separation activated sludge method, and the generation of surplus sludge is reduced or basically not generated. Therefore, it was urgent to develop a means that can take measures such as predicting and detecting troubles and temporarily avoiding irreversible deterioration of membrane permeability.
JP-A-7-75782 Japanese Patent Laid-Open No. 9-75938 JP 2003-53363 A JP 2004-306026 A

  The present invention has been made in response to the above-mentioned problems in the prior art, and its purpose is to prevent the membrane separation activity of a liquid containing a soluble organic substance while preventing membrane permeability failure, foaming, scum generation, viscosity increase, and the like. The object is to provide a method for treating sludge and a treatment apparatus therefor.

  In order to solve the above problems, the present invention has the following configuration.

(1) When processing a soluble organic substance-containing liquid by the membrane separation activated sludge method, CFB group bacteria and / or CFB in which several bacteria are chained free and growing in the sludge mixed liquid alone Monitor at least one selected from the abundance, concentration, predominance of group bacteria, and changes in characteristics over time, reduce the amount of membrane filtration water per hour, reduce suction pressure, stop membrane filtration, membrane filtration operation Reduced time, reduced or stopped inflow of soluble organic matter, added flocculant, adjusted pH, adjusted temperature, adjusted aeration rate, adjusted agitation conditions, adjusted sludge load, contained in soluble organic matter-containing liquid Type of pollutant, addition of chemicals and specific viruses, addition of oxidizer, recovery of generated foam, adjustment of addition amount of nitrogen, phosphorus, magnesium or trace elements, adjustment of sludge extraction amount, adjustment of water retention time At least one selected from transition to intermittent filtration system, shortening of membrane filtration operation time during intermittent filtration, adjustment of adjustment tank for adjusting inflow load fluctuation, change of aeration method, improvement of sludge flow state in tank processing method dissolve organic matter-containing liquid you and performing One.

(2) The method for treating a soluble organic substance-containing liquid according to (1), wherein the operation is performed with a BOD sludge load of less than 0.15 kg-BOD / kg-VSS / day.

(3) CFB group bacteria present in the filtrate obtained by centrifuging the sludge mixed solution with a filter having a pore size of 10 μm or less or a centrifugal supernatant obtained by centrifuging at 3000 × g or more and 3 minutes or more. By monitoring at least one selected from the abundance, concentration, dominance, and change in characteristics over time, the CFB group bacteria and / or several of the The method for treating a solution containing a soluble organic substance according to (1) or (2), wherein monitoring of the state of CFB group bacteria to which bacteria are linked is realized.

(4) a biological reaction tank for treating a soluble organic substance-containing liquid with activated sludge, a separation membrane for solid-liquid separation in the sludge mixed liquid, a CFB group bacterium that is free and grows in the sludge mixed liquid, and And / or monitoring means for monitoring at least one selected from the number of CFB group bacteria linked to several bacteria, concentration, dominance, change in characteristics over time, and based on the result of the monitoring means, Reduction of membrane filtration water volume per hour, reduction of suction pressure, stop of membrane filtration, reduction of membrane filtration operation time, reduction or stop of inflow of soluble organic matter, addition of flocculant, pH adjustment, temperature adjustment, Adjustment of aeration volume, adjustment of agitation conditions, adjustment of sludge load, adjustment of the type of pollutants contained in liquids containing soluble organic substances, addition of chemicals and specific viruses, addition of oxidizing agents, recovery of generated bubbles, nitrogen or phosphorus Or magnesi Adjustment of amount of water or trace elements, adjustment of sludge extraction amount, adjustment of water retention time, transition to intermittent filtration method, reduction of membrane filtration operation time during intermittent filtration, adjustment of adjustment tank to adjust inflow load fluctuation , change of diffuser methods, improvement of the sludge flowing state in the tank, at least one control means for performing that have the dissolve organic matter-containing liquid processing apparatus selected from.

(5) The processing apparatus for a soluble organic substance-containing liquid according to (4), wherein the biological reaction tank has means for keeping the BOD sludge load below 0.15 kg-BOD / kg-VSS / day.

(6) The monitoring means is present in the filtrate obtained by filtering with a filter having a pore size of 10 μm or less by centrifuging the sludge mixed solution with 3000 × g or more and centrifuging for 3 minutes or more. By monitoring at least one selected from the abundance, concentration, dominance, and change in characteristics of CFB group bacteria over time, CFB group bacteria that are free and growing in the sludge mixture and / or Alternatively, the apparatus for treating a solution containing a soluble organic substance according to (4) or (5), which monitors the state of a CFB group bacterium in which several bacteria are linked.

  According to the present invention, when a soluble organic substance-containing liquid is treated by the membrane separation activated sludge method, the treatment is performed while monitoring the state of CFB group bacteria dispersed and present in the sludge mixed liquid. Predict and detect increases in viscosity and clogging of membranes. Furthermore, since the processing conditions are controlled based on the monitoring results, measures can be taken at an early stage, and various phenomena that impair processing stability such as poor membrane permeability and foaming and scum are temporarily generated. Can be avoided or prevented in advance. Moreover, the property of sludge can be easily analyzed with high accuracy.

Hereinafter, the present invention will be described in detail and specifically.
In the present invention, the membrane separation activated sludge method is a method that uses membrane separation to obtain a clear treatment liquid by removing organic substances in the soluble organic substance-containing liquid and nitrogen / phosphorus by microorganisms in the activated sludge and obtaining a clear treatment liquid. I mean. The membrane separation method is not particularly limited, such as an immersion membrane method, an external membrane separation method, and a rotating flat membrane method.

  In the present invention, the CFB group bacterium is a group of bacteria defined by molecular phylogeny, and refers to a group of bacteria classified into Bacteroides (Phylum Bacteroides). The classification of bacteria is described in “Bergey's Manual of Systematic Bacteriology” (edited by George M. Garrity et al., 2nd edition, Springer Fairerk (Springer). Verlag), 2002, p.119-166), and various phylogenetic classification services can be used.

  The state of CFB group bacteria refers to the number, concentration, dominance, characteristics, etc. of CFB group bacteria.

  Here, being dispersed in the sludge mixed solution means not existing in the floc. A floc is an aggregate in which a plurality of microorganisms in activated sludge are bonded to each other via an extracellular polymer, etc., and the major axis exceeds 10 μm (however, filamentous bacteria are not included when defining the diameter) Point to something. Bacteria that are dispersed in the sludge mixture include, for example, bacteria that are free and growing alone, bacteria that are linked to several bacteria (diococci and streptococci), and floc. Not contained filamentous bacteria, and can be confirmed by optical microscope observation.

  In the present invention, a soluble organic substance-containing liquid such as waste water is treated by, for example, the treatment apparatus shown in FIG. 1, and the finally obtained clarified liquid is soluble organic substance to such an extent that it can be discharged into a river or the like as it is. Has been disassembled. Examples of the soluble organic substance-containing liquid to be treated here include industrial wastewater and domestic wastewater, and can be more suitably used for industrial wastewater discharged from food factories. Moreover, it can use further more suitably with respect to the soluble organic substance containing waste water which has polysaccharide as a main component.

  The processing apparatus shown in FIG. 1 includes a biological reaction tank 1 containing sludge containing microorganisms, a raw solution pump 4 for supplying a raw solution to the biological reaction tank 1, and a membrane separation for solid-liquid separation of the biologically processed processing liquid. A device 2, a suction pump 3 for sucking the separated liquid during solid-liquid separation, a monitoring means 7 for monitoring the state of CFB group bacteria dispersed and present in the sludge mixed liquid in the biological reaction tank 1, and monitoring And a processing condition control device 8 for controlling processing conditions based on the result of the means 7. The membrane separation device 2 is immersed in a treatment liquid in the biological reaction tank 1, and oxygen is supplied below the membrane separation device 2 to advance the aerobic treatment and to clean the membrane surface. An aeration device 5 connected to is provided. In addition, a sludge extraction pump 13 for extracting excess sludge as necessary is installed below the biological reaction tank 1.

  The biological reaction tank 1 contains sludge containing microorganisms, and these microorganisms act as organic matter-degrading bacteria and further decompose these microorganisms to perform biological treatment. Microorganisms contained in sludge contribute to the degradation of soluble organic matter such as bacteria, yeasts and fungi including fungi, and are obtained from nature, such as soil, compost, and sludge, by accumulating culture and acclimatization. The It is also possible to isolate and use the main microbial group involved in the degradation from this conditioned solution.

  The biological reaction tank 1 must contain other components necessary for the growth of microorganisms. Therefore, for example, nitrogen, phosphorus, potassium, sodium, magnesium and other metal salts are added to the bioreactor, except when already contained in the stock solution.

  As the membrane separation device 2 provided in the biological reaction tank 1, a module formed using a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, or the like can be used. From the economical point of view, a module using a microfiltration membrane or an ultrafiltration membrane that has a high filtration rate and can be made compact and is easy to maintain is preferable. The membrane may be a flat membrane, a hollow fiber membrane or the like. The form of the module is not particularly limited, but in this embodiment, an immersion type membrane module is used for space saving. In the case of the immersion type, the shape is preferably such that the fouling substance can be successfully removed by combination and arrangement with an aeration apparatus or a stirring apparatus. Furthermore, as a filtration method in the membrane separation device 2, there are a cross flow method and a total amount filtration method. If the cross flow method is employed, filtration can be performed while removing the membrane surface.

  Hereinafter, a method for monitoring dispersed bacteria will be described.

  As the monitoring means 7 for monitoring the state of the CFB group bacteria dispersed and existing in the sludge mixed liquid in the biological reaction tank 1, the state of the CFB group bacteria dispersed and present in the sludge mixed liquid is efficiently monitored. For example, an image recording means attached to the microscope and an automatic monitoring means using the image analysis means can be used. In this case, the microscope observation means is used after fluorescently staining the sludge mixed solution. It can also be used.

However, because of its simplicity, it is desirable to first detect a sample that efficiently collects microorganisms that are dispersed and present in the sludge mixture. As an example of a sample in which microorganisms present in a dispersed state in a sludge mixed liquid are efficiently collected, a centrifugal supernatant liquid, a filter filtrate, and the like can be considered. This is because the size of microorganisms present in a dispersed state is smaller than the floc of sludge, and therefore, microorganisms present in a dispersed state and other microorganisms can be separated by centrifugation or filter filtration. Specifically, the microorganisms present in a dispersed state are obtained in the supernatant in the case of centrifugation and in the filtrate in the case of filter filtration. The centrifugal supernatant is obtained, for example, by centrifuging the sludge mixed solution at 3000 × g (about 29420 m / s ² ) for 3 minutes, and the filter filtrate is obtained by, for example, filtering through a filter having a pore diameter of 10 μm. . In addition, it can be obtained by filtering with filter paper, non-woven fabric, or glass filter. Specifically, solid-liquid separation means such as a centrifugal separator or a filtration unit may be used.

  Next, a method for monitoring CFB group bacteria will be described.

  The measurement item for the sample obtained by using the above method or the like is not particularly limited as long as it can efficiently monitor the state of the CFB group bacteria. As a monitoring method, CFB group bacteria can be grown and monitored by a plate culture method using a selective medium. For example, as described below, genetic information, RNA transcription characteristics, protein of CFB group bacteria It is preferable to observe the existence number, concentration, dominance, change in characteristics over time, and the like based on the translation characteristics, the generated substance characteristics, etc., because it is highly accurate and efficient.

  Specifically, when monitoring based on genetic information, a fluorescence measurement device such as a fluorescence microscope or a fluorescence image scanner, a nucleic acid hybridization detection device, a flow cytometer, a thermal cycler, and an electrophoresis device may be used. . In addition, when monitoring based on gene expression characteristics such as RNA transcription characteristics, protein translation characteristics, and expressed protein product characteristics, fluorescence microscope, flow cytometer, electrophoresis apparatus, mass spectrometer, image analyzer, spectrophotometer A meter, a fluorescence measurement device, a light emission amount measurement device, or the like may be used.

  Methods for monitoring the number, concentration, and dominance of CFB group bacteria based on genetic information include methods based on hybridization homology values of the entire chromosome genome and methods based on gene sequences specific to CFB group bacteria. However, it is preferable to perform monitoring based on the method based on the gene sequence specific to the latter CFB group bacteria from the viewpoint that it can be easily confirmed efficiently and substantially. Specific gene sequence targets include 16S ribosomal RNA gene, 23S ribosomal RNA gene, gyrB gene sequence, spacer region between ribosomal RNA genes, and the like. The monitoring target may be all or part of the CFB group bacteria, and may further include other bacteria as long as the CFB group bacteria can be monitored.

  When monitoring the dominance of CFB group bacteria, for example, measurements that reflect the number of total prokaryotes, total bacteria, and bacteria in a certain taxonomic group as much as possible are performed at the same time. Should be calculated.

  As a method for monitoring a specific gene sequence, a known method can be used. For example, a region specific to a CFB group bacterium is selected from gene sequence information, and an oligonucleotide or polynucleotide having the gene sequence is selected. It is preferable to use a method that utilizes the hybridization efficiency of Specifically, dot hybridization methods, microarray methods, in situ hybridization methods, etc. can be used using fluorescent substances, radioisotopes, enzymatic reporter molecules, electroactive intercalators, etc. Depending on the method, gene amplification by polymerase chain reaction (PCR) or the like can be combined with these methods. As the in situ hybridization method, a fluorescence in situ hybridization method (FISH method) using a fluorescently labeled oligonucleotide or a fluorescently labeled polynucleotide can be used. In addition, what is necessary is just to implement a FISH method, enhancing a signal as needed. The detection method using the FISH method may be a method using a fluorescence microscope or a method using a flow cytometer. In the dot hybridization method and the microarray method, oligonucleotides or polynucleotides having gene sequences specific to CFB group bacteria are immobilized on a membrane filter or substrate, and nucleic acid derived from the sludge to be detected is fluorescent with a fluorescent substance or the like. Examples include a method in which a labeled substance is hybridized.

  As a method of utilizing the hybridization efficiency of an oligonucleotide or polynucleotide having a 16S ribosomal RNA gene sequence specific to CFB group bacteria, a DNA or RNA probe capable of specifically hybridizing with a nucleic acid of CFB group bacteria can be used. Good. For example, the DNA probe “CFB560” (Louis A. O'Sullivan et al., Two persons, Applied and Environmental Microbiology (Appl. Environ. Microbiol.), 2002, volume 68. , P.201-210.). Of course, in addition to this probe, any probe designed to be able to detect CFB group bacteria by hybridization can be used.

  As a method for monitoring a specific gene sequence, there is also a method for detecting and quantifying by applying a polymerase chain reaction method (PCR) using a primer DNA having a gene sequence specific to CFB group bacteria. Examples of such a method include a quantitative PCR method in which nucleic acid amplification is detected in real time using a primer set specific to CFB group bacteria. Furthermore, the genomic DNA of microorganisms contained in the sludge mixture is extracted, PCR amplification is performed using a primer set specific for prokaryotes in general, bacteria in general or a narrower taxonomic group, and CFB group bacteria are obtained by electrophoresis. It is also possible to sort and monitor the gene sequence of. As this electrophoresis method, denaturant concentration gradient gel electrophoresis (DGGE) can be used.

  Furthermore, as a method for monitoring CFB group bacteria, its gene expression characteristics can be used. Gene expression characteristics refer to RNA transcription characteristics, protein translation characteristics, and product substance characteristics (for example, expressed protein product substance characteristics) from the CFB group bacterial genome. Bacteria that are dispersed and grown in the sludge mixed solution vary greatly in the properties of the bacteria due to differences in growth conditions such as whether they grow in a floc or disperse. Therefore, tracking the changes in the properties of CFB group bacteria with gene expression characteristics is very useful in the operational stability of the membrane separation activated sludge method. This makes it possible to more accurately predict and detect problems and take countermeasures. The target of gene expression characteristics is not particularly limited, and may be any constituent gene or regulatory gene.

  The target of the RNA transcription characteristic may be either messenger RNA or ribosomal RNA. Various known methods can be used for monitoring these RNA transcription characteristics, such as a method for analyzing the abundance of messenger RNA by hybridization, a method using a DNA chip using an image analyzer, and the like. Is mentioned. Also, the FISH method can be used.

  Moreover, the target protein of the protein translation property is not particularly limited, and examples thereof include a morphological change-inducing protein, a dispersed expression protein, and an extracellular polymer-forming protein. As a method for monitoring protein translation characteristics, various known protein analysis methods such as two-dimensional electrophoresis, Western blot, and mass spectrometer can be used.

  Furthermore, it is not particularly limited as a target of the product substance characteristics, and examples thereof include extracellularly generated polymers and intracellular components. Examples of methods for monitoring extracellularly produced polymers and intracellular components include methods using a liquid chromatography device, a gas chromatography device, a mass spectrometer, a spectrophotometer, a fluorescence measuring device, a luminescence measuring device, etc. An ELISA method using an antibody-antigen reaction can also be applied.

  The monitoring means 7 is connected to a processing condition control device 8 that controls processing conditions based on the monitoring result. Although the processing condition control device 8 is not particularly limited, it issues a processing condition adjustment signal 9 based on the monitoring result to the suction pump 3 or the like to reduce the amount of membrane filtration water and suction pressure per hour, stop membrane filtration, Reduce the membrane filtration operation time, reduce or stop the inflow of soluble organic matter, and add flocculants.

  Moreover, the process condition adjustment signal 10 for controlling the atmosphere of the biological reaction tank 1 can be issued to adjust the pH, temperature, aeration amount, and stirring conditions. Furthermore, a processing condition adjustment signal 11 for controlling the detailed conditions of the soluble organic substance-containing liquid flowing into the biological reaction tank 1 is issued, adjusting the sludge load amount, adjusting the type of the pollutant contained in the soluble organic substance-containing liquid, antibiotics, etc. It is possible to add chemicals and specific viruses, add oxidizers such as ozone and chlorine, collect bubbles generated by foaming equipment, and adjust the amount of components such as nitrogen, phosphorus and magnesium, and trace elements. . And in order to control the sludge residence time in the biological reaction tank 1, the process condition adjustment signal 12 can be emitted and the sludge extraction amount can also be adjusted. Furthermore, the water residence time can be adjusted through these adjustments.

  Through trials of these methods, control is performed so as to temporarily avoid irreversible deterioration in membrane permeability or to approach the monitoring situation before trouble occurs. In addition, the type adjustment of the pollutant is, for example, when sugar wastewater and lipid wastewater discharged in separate processes are mixed and biologically treated, the input of sugar wastewater is temporarily suspended or the ratio is reduced, and the lipid wastewater is reduced. It is an adjustment that increases the input ratio temporarily.

  Among these process condition adjustment methods, reduction of membrane filtration water volume and suction pressure per hour, transition to intermittent filtration method, shortening of membrane filtration operation time during intermittent filtration, stop of membrane filtration, inflow of soluble organic matter It is preferable to reduce or stop the volume, adjust the adjustment tank to adjust the inflow load fluctuation, add a flocculant, change the aeration amount / aeration method, improve the sludge flow state in the tank, etc. It is more preferable to reduce the amount of filtered water and suction pressure, shorten the membrane filtration operation time during intermittent filtration, stop membrane filtration, and improve the sludge flow state in the tank.

  In the processing apparatus configured as described above, the soluble organic substance-containing liquid is processed as follows. The soluble organic substance-containing liquid is supplied to the biological reaction tank 1 by the stock solution pump 4, and the soluble organic substance is decomposed by the activated sludge in the biological reaction tank 1. At this time, the biological reaction tank 1 is kept aerobic by being supplied with oxygen by the aeration apparatus 5 connected to the blower 6. Then, the sludge mixed liquid is supplied to the membrane separation device 2 and separated into activated sludge and a clear treatment liquid. The clear treatment liquid is discharged as it is into a river, for example, and the activated sludge is left in the biological reaction tank 1.

  Here, in the present invention, the amount of sludge withdrawn is adjusted according to the amount of soluble organic matter to be processed per hour, and the sludge load in the biological reaction tank 1 is made less than 0.15 kg-BOD / kg-VSS / day. preferable. That is, the sludge concentration is increased by reducing the sludge extraction amount, and as a result, the sludge load is made less than 0.15 kg-BOD / kg-VSS / day. By making the sludge load less than 0.15 kg-BOD / kg-VSS / day, it is possible to obtain an effect that excess sludge is reduced or basically not generated as compared with the conventional membrane separation activated sludge method. At this time, since the sludge load is “the amount of soluble organic matter to be treated per hour / microbe concentration (MLVSS)”, an appropriate amount of sludge extraction is determined according to the amount of soluble organic matter to be treated per hour, and the sludge concentration is determined. By adjusting, the sludge load becomes less than 0.15 kg-BOD / kg-VSS / day. Therefore, it is not necessary to specifically limit the sludge concentration itself, and the sludge concentration is defined so as to obtain an appropriate sludge load according to the amount of soluble organic matter to be processed per hour.

  The sludge load can also be set lower depending on the raw water quality such as the sludge properties, the magnitude of necessity for reducing excess sludge, and the cell conversion rate of soluble organic components contained in the raw water. From the viewpoint of reducing excess sludge, it is more preferable to adjust to less than 0.10 kg-BOD / kg-VSS / day, and most preferably to less than 0.08 kg-BOD / kg-VSS / day. It should be noted that excessive sludge cake formation on the submerged membrane, which tends to occur as the sludge concentration increases, can be improved by measures such as rocking and backwashing.

  However, when such a low sludge load operation is performed, troubles with deterioration of membrane permeability, foaming, generation of scum, increase in viscosity, etc. often occur. As a result of diligent research, the cause is not clear, but it has been found that these troubles involve the state of CFB group bacteria dispersed and present in the sludge mixture. In order to cope with this problem and to achieve a balance with the effect of reducing or basically not generating the excess sludge, in the present invention, the state of CFB group bacteria present dispersed in the sludge mixed solution by the monitoring means 7 The processing condition control device 8 adjusts the processing conditions based on the monitoring result. By monitoring the CFB group bacteria dispersed in the sludge mixture, it is possible to predict and detect membrane problems at an early stage while reducing sludge load and reducing the generation of excess sludge. Can be taken.

  Conventionally, it has been known that the sludge load increases by lowering the MLSS concentration, and that dispersal bacteria that do not form flocs under these conditions are a problem (Patent Document 3), but the cause of the occurrence of dispersal bacteria is high load. (Takiguchi, “Water and Wastewater”, 2000, Vol. 42, No. 9, p35-42). However, the inventors have a very low sludge load as a whole tank, and disperse prokaryotes are generated even in a state completely different from the situation where BOD is abundant, which is the cause of trouble. And found that they are CFB group bacteria. That is, the present invention is a disperse prokaryote whose generation mechanism is different from the conventionally known dispersible microorganisms, and the bacteria belonging to the CFB group are a cause of trouble mainly in a low sludge load state. By monitoring them based on the findings, it was possible to predict and detect troubles at an early stage and to take various measures.

  In addition, since troubles occur when CFB group bacteria appear in a dispersed state, a signal that leads to troubles with much higher accuracy than by monitoring CFB group bacteria in the entire sludge by monitoring dispersed CFB group bacteria. Can be grabbed. This is because when detecting CFB group bacteria in the entire sludge, it will also detect useful CFB group bacteria in the floc, so the signal of dispersed CFB group bacteria that actually cause troubles is overlooked. Because it ends up. In general, many CFB group bacteria contribute to the degradation of pollutants such as polysaccharides and the degradation of dead bacteria, and contain many microorganisms that are useful for the membrane separation activated sludge method. By using the method of the present invention, CFB group bacteria that lead to troubles can be detected efficiently.

  On the other hand, the method previously proposed by the present inventors to detect the state of the Fructobacillus strain group bacteria, which are specific trouble-related microorganisms present in the sludge mixed solution, is the limited microorganism group actually involved in troubles. Therefore, it is possible to detect the entire sludge as a target without squeezing and detecting the detection target in microorganisms present in a dispersed manner. Furthermore, by being able to detect the entire sludge, it is excellent in that the trend can be monitored from the time when the Bacteroides strain bacteria are present in the floc without being dispersed, and an effect different from the present invention can be obtained. Therefore, a method for detecting a limited microbial group such as a bacterium from the group of Streptobacillus strains may be used separately or in combination with the method of the present invention depending on the situation.

  On the other hand, in the present invention, after the monitoring target is narrowed down to microorganisms that are present in a dispersed manner, the monitoring microorganism is not a Fractobacillus strain group bacteria but a CFB group bacteria that is a classification group including them.

  The reason why CFB group bacteria are used as monitoring microorganisms is that CFB group bacteria are usually considered to have useful properties in the membrane separation activated sludge method as described above. Is based on the knowledge that it is involved in trouble. Specifically, not only the previously proposed Flectobacillus strain group bacteria, for example, a bacterium having the base sequence of SEQ ID NO: 1 in the 16S ribosomal RNA gene, a bacterium having the base sequence of SEQ ID NO: 2 in the 16S ribosomal RNA gene, etc. Bacteria located in a wide phylogenetic position of the CFB group are involved in trouble. Although the detailed mechanism by which the CFB group bacteria that have grown in a dispersed manner are involved in the trouble is still unknown, there is a possibility that biosurfactants and extracellular polymers unique to the CFB group bacteria may be involved in the trouble of the membrane separation activated sludge method. It is done. Next, the merit of using the entire CFB group bacteria as a detection target will be described. When the detection target is a limited group of microorganisms in the CFB group bacteria, there is a merit that sensitivity is increased, but it is necessary to increase the detection system accordingly. On the other hand, if this is utilized based on the discovery that the bacteria that cause trouble by dispersion as described above are CFB group bacteria, the detection target can be made large, such as CFB group bacteria. There is a merit that becomes simpler. In fact, when dispersal bacteria are the detection target, sufficient accuracy can be obtained by using the normal CFB group bacteria as the detection target. In other words, when considering points such as simplification of the detection system and cost reduction, it is desirable to widen the detection target within a range where there is no problem in detection accuracy, and it is necessary to determine the optimal detection target range from that viewpoint. . Since microorganisms involved in trouble due to dispersed growth belong to the CFB group as described above, the range of CFB group bacteria is preferable. That is, when the detection target range is expanded as much as possible from the viewpoint of simplification and cost reduction within the range where the effect is recognized, it is understood that the maximum detection target range should be the CFB group bacteria. On the other hand, the present inventors have proposed a method for monitoring prokaryotic organisms present in a dispersed manner, but this method is also inferior to the present invention but can provide a certain degree of accuracy. This method can also be employed when simplification of the detection system and cost are a problem.

<Example 1>
(1) Prepare two series of membrane separators, which are modularized PVDF microfiltration membranes with a pore size of 0.1 μm, immersed in a biological reaction tank with an effective volume of 30 L. Treated by the separated activated sludge method. The MLSS concentration (mixed liquid suspended substance concentration) was fixed at 24.0 g / L by extracting the sludge, and the residence time of the artificial wastewater in the biological reaction tank was set to 1 day (BOD sludge load: 0.05 kg). -BOD / kg-VSS / day). In addition, the sludge mixture was periodically centrifuged at 3000 × g (about 29420 m / s ² ) for 3 minutes, and the CFB group bacteria contained in the supernatant were monitored by the FISH method. However, no CFB group bacteria were detected (10 ⁶ cells / mL or less). The FISH method was performed using DNA probe “CFB560” (Louis A. O'Sullivan et al., Applied and Environmental Microbiology (Appl. Environ. Microbiol.), 2002. , Vol. 68, p. 201-210.) Was performed on CFB group bacteria contained in a 4% paraformaldehyde-fixed sample of the supernatant based on the literature of the probe developers. In addition, whole bacterial staining with DAPI (4 ′, 6-diamidino-2-phenylindole dihydrochloride) and DNA probe “EUB338” (Rudolf I. Amman and others, Applied and Enviro The concentration of CFB group bacteria using the FISH method using mental microbiology (Appl. Environ. Microbiol., 1990, 56, pp. 1919-1925.) Was calculated.

(2) Thereafter, biological treatment was carried out with the BOD concentration of dextrin-based artificial wastewater supplied to the biological reaction tank being alternately changed to 750 ppm or 1250 ppm every 6 hours, and the CFB group bacteria were monitored 7 days after the BOD concentration was changed. As a result, the sludge concentration and viscosity of the sludge mixed liquid in the biological treatment tank were constant before and after the change, and were 24.0 g / L and 23 mPa · s, respectively. 10 ⁷ pieces / mL were detected.
(3) As a result of monitoring the state of CFB group bacteria present in a dispersed state, the concentration increased as described above, and as a control means against this, load fluctuation was suppressed for one of the two series. It was. In other words, the BOD concentration of the dextrin artificial wastewater flowing into the biological reaction tank is returned to 1000 ppm again (series A). For the other series, the BOD concentration of the dextrin artificial wastewater flowing into the biological reaction tank is kept as it is every 6 hours. Biological treatment was carried out alternately at 750 ppm or 1250 ppm (series B). As a result, the viscosity of the series B sludge mixed liquid increased to 100 mPa · s after 3 days and the differential pressure between the PVDF membrane raw solution side and the filtrate side increased, whereas the viscosity of the series A remained almost unchanged at 25 mPa · s.・ It was s, and no increase in differential pressure was observed.

When CFB group bacteria contained in the supernatant were monitored by the FISH method, no CFB group bacteria were detected in line A (10 ⁶ cells / mL or less), whereas in line B, CFB group bacteria were about 5 × 10 6. ^Nine / mL were detected.
(4) By monitoring the CFB group bacteria dispersed and present in the sludge mixture as described above, it is possible to predict the deterioration of membrane permeability that is seen in the differential pressure increase earlier than the viscosity is monitored. By dealing with this, it was possible to prevent an increase in viscosity and poor membrane permeability.

<Example 2>
(1) A membrane separation device in which a PVDF microfiltration flat membrane with a pore size of 0.1 μm is modularized is prepared by immersing it in a biological reaction tank with an effective volume of about 1 L, and BOD 500 ppm dextrin artificial wastewater is membrane-separated Treated by activated sludge method. As a result of treating the residence time of the artificial wastewater in the biological reaction tank as 12 hours, the MLSS concentration was constant at 20 g / L without extracting the sludge (BOD sludge load: 0.06 kg-BOD / kg-VSS / day). In addition, a part of the sludge mixed solution was periodically centrifuged at 3000 × g (about 29420 m / s ² ) for 3 minutes, and the CFB group bacteria contained in the supernatant were subjected to an example. As in 1, it was monitored by FISH method, but no CFB group bacteria were detected (10 ⁶ cells / mL or less).

(2) Membrane separation activated sludge treatment was further continued for 2 weeks, and CFB group bacteria contained in the supernatant were measured by the FISH method. As a result, approximately 4 × 10 ⁷ CFB group bacteria / mL were detected. On the other hand, a DNA probe “R-FL615” (Karel Simek et al., 7 people, Applied and Environmental Microbiology (Appl. Environ. Microbiol.) For detecting bacteria of the family of Streptobacillus, 2001, Vol. 67, p. 2723-2733.) As a result of detection by the FISH method, no bacteria of the Streptococcus strain group were detected (10 ⁶ cells / mL or less).

(3) As a result of monitoring the state of CFB group bacteria present in a dispersed state, the concentration increased as described above, and thus fluidity was confirmed and improved as a control means for this. That is, when the state of sludge flow in the tank was checked, there was a portion where the sludge was stuck on the inner wall of the tank and did not flow. Therefore, the sticky sludge was removed to make it flowable. As a result, one week later, when the CFB group bacteria in the centrifugation supernatant were measured by the FISH method, no CFB group bacteria were detected (10 ⁶ cells / mL or less).

  (4) Even if the membrane-separated activated sludge treatment was continued for another 2 weeks, no troubles such as deterioration of membrane filterability occurred.

  (5) Thus, by monitoring the CFB group bacteria dispersed and present in the sludge mixed liquid, it was possible to prevent deterioration of membrane permeability.

<Example 3>
(1) A membrane separation device in which a PVDF microfiltration flat membrane with a pore size of 0.1 μm is modularized is prepared by immersing it in a biological reaction tank with an effective volume of about 8 L, and BOD 500 ppm dextrin artificial wastewater is membrane-separated Treated by activated sludge method. As a result of treating the residence time of the artificial wastewater in the biological reaction tank as 12 hours, the MLSS concentration was constant at 24 g / L without extracting the sludge (BOD sludge load: 0.05 kg-BOD / kg-VSS / day). In addition, a part of the sludge mixed solution was periodically centrifuged at 3000 × g (about 29420 m / s ² ) for 3 minutes, and the CFB group bacteria contained in the supernatant were subjected to an example. As in 1, it was monitored by FISH method, but no CFB group bacteria were detected (10 ⁶ cells / mL or less).

(2) Membrane separation activated sludge treatment was further continued for 3 weeks, and CFB group bacteria contained in the supernatant were measured by the FISH method. As a result, CFB group bacteria were detected (about 2 × 10 ⁷ cells / mL). As a result of monitoring the state of the CFB group bacteria present in a dispersed state, the concentration increased as described above. The cause was unknown, but the inflow load was stopped as a control means. In other words, the flow of artificial wastewater was temporarily stopped and changed to a flow for supplying tap water instead.

(3) As a result, one week later, when the CFB group bacteria in the centrifugation supernatant were measured by the FISH method, no CFB group bacteria were detected (10 ⁶ cells / mL or less).

  (4) Even if the membrane-separated activated sludge treatment was continued for another 2 weeks, no troubles such as deterioration of membrane filterability occurred.

  (5) Thus, by monitoring the CFB group bacteria dispersed and present in the sludge mixed liquid, it was possible to prevent deterioration of membrane permeability.

<Example 4>
(1) A membrane separation device in which a PVDF microfiltration flat membrane with a pore size of 0.1 μm is modularized is prepared by immersing it in a biological reaction tank with an effective volume of about 1 L, and BOD 500 ppm dextrin artificial wastewater is membrane-separated Treated by activated sludge method. As a result of treating the residence time of the artificial wastewater in the biological reaction tank as 12 hours, the MLSS concentration was constant at 20 g / L without extracting the sludge (BOD sludge load: 0.06 kg-BOD / kg-VSS / day). Moreover, the microscopic observation of the sludge mixed liquid was performed regularly over one week.

(2) As a result of continuing the membrane separation activated sludge treatment for another week, 3 × 10 ⁷ prokaryotes present in a dispersed state were observed by microscopic observation. Here, when the detection of CFB group bacteria was attempted by the FISH method in the same manner as in Example 1, no CFB group bacteria were detected (10 ⁶ cells / mL or less).

  (3) On the other hand, when the FISH method was performed using not the supernatant but the entire sludge as a sample, CFB group bacteria of at least 10% or more of the microorganisms in the sludge were detected.

  (4) Even if the membrane-separated activated sludge treatment was continued for another 2 weeks, no troubles such as deterioration of membrane filterability occurred.

It is a schematic flowchart of the processing apparatus which shows one Embodiment of this invention.

Explanation of symbols

1: Bioreaction tank 2: Membrane separation device 3: Suction pump 4: Stock solution pump 5: Aeration device 6: Blower 7: Monitoring means 8: Treatment condition control device 9-12: Treatment condition adjustment signal 13: Sludge extraction pump

Claims (6)

When a soluble organic substance-containing liquid is treated by the membrane separation activated sludge method, CFB group bacteria and / or CFB group bacteria in which several bacteria are linked in a sludge mixed solution are separated and grown. Monitor at least one selected from the number of existence, concentration, dominance, and change in characteristics over time to reduce the amount of membrane filtration water per hour, reduce suction pressure, stop membrane filtration, reduce membrane filtration operation time , Reduction or termination of inflow of soluble organic matter, addition of flocculant, adjustment of pH, adjustment of temperature, adjustment of aeration amount, adjustment of stirring conditions, adjustment of sludge load, pollutant contained in liquid containing soluble organic matter Type adjustment, addition of chemicals and specific viruses, addition of oxidizing agent, recovery of generated foam, adjustment of addition amount of nitrogen, phosphorus, magnesium or trace elements, adjustment of sludge extraction amount, adjustment of water retention time, intermittent At least one selected from the transition to the excess method, shortening the membrane filtration operation time during intermittent filtration, adjusting the adjustment tank to adjust the inflow load fluctuation, changing the air diffusion method, improving the sludge flow state in the tank processing method dissolve organic matter-containing liquid you and performs. 2. The method for treating a soluble organic substance-containing liquid according to claim 1, wherein the operation is performed with a BOD sludge load of less than 0.15 kg-BOD / kg-VSS / day. Number of CFB group bacteria present in the filtrate obtained by centrifuging the sludge mixed solution with a filter having a pore size of 10 μm or less or a centrifugal supernatant obtained by centrifuging at 3000 × g or more and 3 minutes or more. By monitoring at least one selected from concentration, dominance, change in characteristics over time, CFB group bacteria and / or several bacteria that are free and growing alone in the sludge mixture are linked. The processing method of the soluble organic substance containing liquid of Claim 1 or 2 which implement | achieves monitoring of the state of the CFB group bacteria currently performed. Biological reaction tank for treating soluble organic matter-containing liquid with activated sludge, separation membrane for solid-liquid separation in sludge mixed liquid, CFB group bacteria and / or number growing independently in sludge mixed liquid Monitoring means for monitoring at least one selected from the time course of the number, concentration, dominance, and characteristics of CFB group bacteria linked to a single bacteria, and based on the results of the monitoring means, Membrane filtration water volume reduction, suction pressure reduction, membrane filtration stop, membrane filtration operation time reduction, dissolved organic matter inflow reduction or stop, flocculant addition, pH adjustment, temperature adjustment, aeration volume Adjustment, adjustment of stirring conditions, adjustment of sludge load, adjustment of the type of pollutants contained in the solution containing soluble organic substances, addition of chemicals and specific viruses, addition of oxidizing agents, recovery of generated foam, nitrogen, phosphorus or magnesium Adjusting the amount of trace elements added, adjusting the amount of sludge extraction, adjusting the water retention time, shifting to the intermittent filtration method, shortening the membrane filtration operation time during intermittent filtration, adjusting the adjustment tank to adjust the inflow load fluctuation , change of diffuser methods, improvement of the sludge flowing state in the tank, at least one control means for performing that have the dissolve organic matter-containing liquid processing apparatus selected from. The biological reaction tank has means for keeping the BOD sludge load below 0.15 kg-BOD / kg-VSS / day, the processing apparatus for a soluble organic substance-containing liquid according to claim 4 . The CFB group present in the filtrate obtained by filtering with a filter having a pore size of 10 μm or less, or a centrifugal supernatant obtained by centrifuging the sludge mixed solution at 3000 × g or more and 3 minutes or more. By monitoring at least one selected from the abundance, concentration, dominance, and change in characteristics of the bacteria over time, the CFB group bacteria and / or several that are growing independently in the sludge mixture. The apparatus for processing a solution containing a soluble organic substance according to claim 4 or 5 , which monitors the state of a CFB group bacterium to which the bacterium is linked.

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