JP6287876B2 - Waste water treatment method and waste water treatment equipment - Google Patents

Description

  The present invention relates to a wastewater treatment method and a wastewater treatment apparatus for treating wastewater containing organic substances such as domestic wastewater and industrial wastewater by activated sludge treatment and membrane filtration.

  As one of the wastewater treatment methods, wastewater containing organic matter is introduced into the treatment tank and treated with activated sludge to remove organic matter etc., and then reverse osmosis membrane, ultrafiltration membrane, microfiltration membrane, hollow fiber membrane, etc. A membrane separation activated sludge method (MBR: Membrane BioReactor) is known in which a membrane module equipped with a separation membrane is passed through, and suspended microorganisms and other suspended substances (abbreviated as SS) are filtered and solid-liquid separated. ing. Since the membrane separation activated sludge method performs solid-liquid separation using a membrane module, the final sedimentation basin can be omitted and the apparatus can be downsized.

  However, there has been a problem that floating microorganisms and other suspended substances (SS) are gradually deposited on the membrane module over a long period of operation, and the separation membrane is clogged. When the separation membrane is clogged, an increase in membrane pressure, a decrease in filtration flux, and the like occur, and the overall operation efficiency of the waste water treatment device decreases. Moreover, finally, the separation membrane must be replaced. If the replacement interval is short, continuous operation is hindered and the cost for the replacement is high. Recently, the main cause of such clogging of the separation membrane is a deposit containing a glycoprotein produced by microorganisms in activated sludge (adhesive property) that exhibits strong adhesion that cannot be removed even by bubbling or backwashing. Including microorganisms and their debris).

  Regarding the membrane separation activated sludge method, for example, in Patent Document 1 below, a small animal having an excellent ability to prey on dispersible bacteria that cause clogging of the separation membrane is introduced into the treatment tank to enhance its feeding effect. Therefore, there is an attempt to solve the problem of clogging of the separation membrane. In addition, for example, in Patent Document 2 below, there is an attempt to solve the problem of clogging of the separation membrane by providing microorganisms that can reduce or prevent the formation of biofilms that cause clogging to the separation membrane. .

  On the other hand, the sludge used for such activated sludge treatment is a conglomerate of microorganisms which are mainly composed of microorganisms in the reaction tank and grow using organic substances in waste water as a substrate. For this reason, the activated sludge treatment purifies organic matter in the wastewater, and the sludge generation amount increases accordingly. In addition, the microorganisms present in the reaction tank are not in a closed system treatment in which no microorganisms are mixed from the outside, and microorganisms that exist universally in the natural world are always mixed. Therefore, there are a wide variety of microorganisms involved in biological treatment and have various characteristics and functions. Therefore, the microorganisms that predominate in the reaction tank by the wastewater to be treated are also different.

  Therefore, it has been proposed to improve the efficiency of wastewater treatment by using a method that predominates Bacillus bacteria that produce a large amount of enzymes that decompose organic matter, and that has a fast growth rate among microorganisms in the wastewater treatment environment. Has been. In this case, in order to dominate and maintain Bacillus bacteria in the treatment tank, an activator containing a silicon compound or a mineral is also added (see Patent Documents 3 and 4 below).

JP 2007-260664 A Special table 2013-510710 gazette Japanese Patent No. 4826982 International Publication No. 2011/136188

  However, regarding the problem of clogging of the separation membrane in the membrane separation activated sludge method, in the method of the above cited reference 1, a small animal having excellent predatory ability of dispersible bacteria is introduced into the treatment tank, which is useful for activated sludge treatment. Even microorganisms were predated, and there was a risk that the wastewater treatment capacity would be hindered. Further, even in the method of the above cited reference 2, since microorganisms that can reduce or prevent the formation of biofilms that cause clogging are provided in the treatment tank, the presence of microorganisms in the treatment tank There was a risk that the growth balance of the plant would be disrupted and the wastewater treatment capacity would be hindered.

  Accordingly, an object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus capable of extending the life of a separation membrane with little influence on the original activated sludge treatment environment in the membrane separation activated sludge method.

  In order to achieve the above-mentioned object, the wastewater treatment method of the present invention introduces wastewater containing organic substances into a treatment tank to perform activated sludge treatment, and discharges wastewater after activated sludge treatment with a separation membrane installed in the treatment tank. A wastewater treatment method for taking out treated water by solid-liquid separation, measuring the clogging state of the separation membrane while predominating microorganisms that improve the clogging state of the separation membrane, The microorganism is activated based on the clogged state of the separation membrane.

  According to the wastewater treatment method of the present invention, the activated sludge treatment is performed in the treatment tank, and the treated water is taken out by solid-liquid separation of the wastewater after the activated sludge treatment with a separation membrane installed in the treatment tank. A tank is not required, and the apparatus configuration can be simplified. In addition, the microorganisms that improve the clogging state of the separation membrane are dominated, and the microorganisms are activated according to the clogging state of the separation membrane, so the clogging of the separation membrane is performed at the desired timing. It can be eliminated, and at least during the period other than the activation process of the microorganism, the inside of the treatment tank can be set in an environment suitable for the activated sludge treatment. Therefore, the life of the separation membrane can be extended with little influence on the original activated sludge treatment environment.

  In the wastewater treatment method of the present invention, it is preferable that the microorganism activation process is performed when an index indicating a clogged state of the separation membrane exceeds a predetermined threshold. According to this, the clogging of the separation membrane can be eliminated at a desired timing at a more accurate time based on the clogging state of the separation membrane.

  In the wastewater treatment method of the present invention, the index indicating the clogged state of the separation membrane is the water pressure of the treated water solid-liquid separated by the separation membrane, and when the water pressure value falls below a predetermined value, It is preferable to activate the microorganism. According to this, the clogging state of the separation membrane can be easily monitored, and the clogging of the separation membrane can be resolved at a desired timing at a more accurate time.

  In the wastewater treatment method of the present invention, the microorganism that improves the clogging state of the separation membrane preferably includes a microorganism that secretes at least a proteolytic enzyme or a carbohydrate-degrading enzyme outside the cell. According to this, even a deposit containing a glycoprotein that exhibits strong adhesion that cannot be peeled off even by bubbling or backwashing can be decomposed and purified to extend the life of the separation membrane. it can.

  In the wastewater treatment method of the present invention, the microorganism activation treatment is preferably a treatment including an increase in proteolytic enzymes and / or carbohydrate degrading enzymes secreted by the microorganisms outside the cells. According to this, even if it is a deposit containing a glycoprotein that shows strong adhesion so as not to be peeled off even by bubbling or backwashing by such activated microorganisms, it is decomposed and purified, The life of the separation membrane can be extended.

  In the wastewater treatment method of the present invention, the microorganism activation treatment is preferably a treatment in which an iron compound and / or a magnesium compound is added to wastewater to be treated with activated sludge in the treatment tank. According to this, since the secretion of proteolytic enzymes and carbohydrate degrading enzymes secreted by microorganisms outside the cells by the added iron compound and magnesium compound occurs, the clogging of the separation membrane can be eliminated at the desired timing. In at least a period other than the activation process of the microorganism, the inside of the treatment tank can be set in an environment suitable for the activated sludge treatment. Therefore, the life of the separation membrane can be extended with little influence on the original activated sludge treatment environment.

  In the wastewater treatment method of the present invention, the microorganism activation treatment is preferably a treatment in which a silicon compound is added to wastewater treated with activated sludge in the treatment tank. According to this, the growth of microorganisms is activated by the added silicon compound, and the proteolytic enzymes and carbohydrate-degrading enzymes secreted by the microorganisms increase accordingly, eliminating clogging of the separation membrane at the desired timing. can do.

  In the wastewater treatment method of the present invention, it is preferable to measure the clogged state of the separation membrane after backwashing or bubbling the separation membrane. According to this, the clogged state of the separation membrane can be monitored more accurately.

On the other hand, the wastewater treatment apparatus of the present invention introduces wastewater containing organic substances into a treatment tank to perform activated sludge treatment, and solid-liquid separates the wastewater after activated sludge treatment with a separation membrane installed in the treatment tank. A wastewater treatment device for taking out treated water,
Means for supplying a microbial activator to improve the clogging state of the separation membrane;
Means for measuring the state of clogging of the separation membrane;
Control means for controlling the supply amount of the activator into the wastewater to be treated with activated sludge in the treatment tank based on the clogged state of the measured separation membrane is provided.

  According to the wastewater treatment apparatus of the present invention, activated sludge treatment is performed in the treatment tank, and the wastewater after the activated sludge treatment is separated into solid and liquid by the separation membrane installed in the treatment tank, and the treated water is taken out. A tank is not required, and the apparatus configuration can be simplified. Further, a means for supplying a microbial activator for improving the clogging state of the separation membrane, a means for measuring the clogging state of the separation membrane, and a treatment based on the measured clogging state of the separation membrane. Because it is equipped with a control means to control the amount of activator supplied to the wastewater that is treated with activated sludge in the tank, microorganisms that improve the state of clogging of the separation membrane are dominant, and clogging of the separation membrane is prevented. Depending on the state, clogging of the separation membrane can be eliminated at a desired timing by supplying the microbial activator, and at least during the period other than when the microbial activator is supplied, It is possible to create an environment suitable for activated sludge treatment. Therefore, the life of the separation membrane can be extended with little influence on the original activated sludge treatment environment.

  In the wastewater treatment apparatus of the present invention, the microorganism that improves the clogged state of the separation membrane is preferably a microorganism that secretes at least a proteolytic enzyme or a carbohydrate degrading enzyme outside the cell. According to this, even a deposit containing a glycoprotein that exhibits strong adhesion that cannot be peeled off even by bubbling or backwashing can be decomposed and purified to extend the life of the separation membrane. it can.

  In the wastewater treatment apparatus of the present invention, the microbial activator preferably contains at least an iron compound or a magnesium compound. According to this, the iron compound or magnesium compound supplied as the activator increases the secretion of proteolytic enzymes and carbohydrate degrading enzymes that are secreted from the cells by the microorganisms. The clogging can be eliminated, and at least during the period other than the time when the activating agent for the microorganism is supplied, the inside of the treatment tank can be kept in an environment suitable for the activated sludge treatment. Therefore, the life of the separation membrane can be extended with little influence on the original activated sludge treatment environment.

  In the waste water treatment apparatus of the present invention, the microbial activator preferably contains at least a silicon compound. According to this, the growth of microorganisms is activated by the silicon compound supplied as the activator, and the proteolytic enzymes and carbohydrate degrading enzymes secreted by the microorganisms increase accordingly. Clogging can be eliminated.

  In the wastewater treatment apparatus of the present invention, it is preferable that the means for measuring the clogged state of the separation membrane includes a means for measuring the water pressure of the treated water solid-liquid separated by the separation membrane. According to this, the clogged state of the separation membrane can be easily monitored.

  According to the wastewater treatment method and the wastewater treatment apparatus of the present invention, in the membrane separation activated sludge method, the life of the separation membrane can be extended with little influence on the original activated sludge treatment environment.

It is a schematic block diagram which shows an example of the waste water treatment apparatus for enforcing the waste water treatment method by this invention. It is a schematic block diagram which shows the other example of the waste water treatment apparatus for enforcing the waste water treatment method by this invention. It is a control flowchart in the control apparatus of the waste water treatment apparatus shown in FIG. It is a control flowchart in the control apparatus of the waste water treatment apparatus shown in FIG. It is a graph which shows the result of having measured the proteolytic activity per cell density | concentration about the Bacillus strain A in the test example 1. FIG. It is a graph which shows the result of having measured the color of the iodine starch reaction about Bacillus strain A in Test Example 2 by the light absorbency of 550 nm. It is a graph which shows the result of having measured the proteolytic activity per cell density | concentration about the Bacillus strain B in the test example 3. FIG. It is a graph which shows the result of having measured the color of the iodine starch reaction about Bacillus strain B in the test example 4 by the light absorbency of 550 nm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an example of a wastewater treatment apparatus for carrying out a wastewater treatment method according to the present invention. This waste water treatment apparatus includes a treatment tank 1 that treats waste water with activated sludge and a membrane module 2 installed in the treatment tank 1, and is a waste water treatment apparatus using a so-called membrane separation activated sludge method. Wastewater from which impurities have been removed in the pretreatment process is introduced into the treatment tank 1 through the flow rate adjustment tank, and activated sludge treatment is performed in the treatment tank 1 after staying for a predetermined time. The treated waste water is sucked by the suction pump 3 through a pipe communicating with the membrane module 2, and the liquid part separated by the separation membrane provided in the membrane module 2 is taken out as treated water. Excess sludge is discharged out of the system by the sludge extraction pump 4 as necessary.

  The wastewater to be treated is not particularly limited as long as it contains nitrogen and organic matter. For example, household wastewater, cereal starch manufacturing industry, dairy manufacturing industry, meat center, sugar manufacturing industry, livestock food manufacturing industry, Examples include wastewater from livestock farming, meat product manufacturing, meat ham / sausage manufacturing, fish paste product manufacturing, fishery food manufacturing, organic chemical industry, and inorganic chemical industry.

  As for the treatment tank 1, any activated sludge containing microorganisms stays in or is put into the tank, and the activated sludge can be treated so that the contaminated components of the wastewater are decomposed and removed by the microorganisms in the activated sludge. There is no particular limitation. Examples thereof include an aeration tank containing aerobic microorganisms such as ammonia oxidizing bacteria and nitrite oxidizing bacteria, and an intermittent aeration tank containing an aerobic microorganisms such as nitrite oxidizing bacteria and anaerobic microorganisms such as denitrifying bacteria.

  As a separation membrane used in the membrane module 2, any general filtration membrane can be used. For example, a reverse osmosis (RO) membrane, an ultrafiltration (UF) membrane, a microfiltration (MF) membrane, a hollow fiber (HF) membrane, etc. are mentioned. Examples of the material for the filtration membrane include polyacrylonitrile, polyimide, polyethersulfone, polyphenylene sulfide sulfone, polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, and polyethylene. The form of the membrane module 2 is not particularly limited, and examples thereof include a hollow fiber membrane module, a flat membrane type module, a spiral type module, and a tubular module.

  In this embodiment, a diffuser plate 5 is provided at the bottom of the treatment tank 1 and below the membrane module 2, and the air from the blower 6 is supplied to the diffuser plate 5 to be processed in the treatment tank 1. The waste water is aerated. The purpose of this aeration treatment is to supply oxygen to the microorganisms in the activated sludge in the tank, but the bubbling action eliminates contaminants that are relatively weakly attached to the membrane module 2, or such contaminants are removed. It also plays a role of preventing the membrane module 2 from adhering.

  In addition, an activator that improves the activity of microorganisms that improve the clogging state of the separation membrane, which will be described later, is supplied from the activator supply tank 7 to the wastewater in the treatment tank 1 by an activator injection pump 8. It has become so. A valve 9 is provided in the middle of the pipe, and the supply amount of the activator is adjusted by opening and closing the valve 9.

  In addition, a pressure sensor 10 is provided in the middle of the pipe communicating with the membrane module 2 to monitor the water pressure of the treated water that has been solid-liquid separated by the separation membrane.

(Wastewater treatment method)
Conventionally, in a wastewater treatment device using the membrane separation activated sludge method, clogging occurs in the separation membrane of the membrane module as the operation progresses, so periodically add water pressure from the treated water side opposite to that during steady operation. Perform backwashing and remove impurities adhering to the membrane module, measure the water pressure of the treated water after solid-liquid separation, and if the water pressure falls below the specified value, take out the membrane module and remove the chemical solution It was necessary to wash the membrane module and finally replace the membrane module.

  In the wastewater treatment method of the present invention, in order to prolong the life of the separation membrane of the membrane module, the state of clogging of the separation membrane is improved in addition to or in place of such maintenance of the membrane module. The microorganisms are dominant, and the microorganisms are activated according to the clogged state of the separation membrane.

  For microorganisms that improve the state of clogging of separation membranes, the main cause of clogging of separation membranes in membrane modules is an activity that shows strong adhesion that cannot be removed by bubbling or backwashing from recent research. It has been clarified that it is a deposit containing glycoprotein produced by microorganisms in sludge (including sticky microorganisms and their debris). And glycoprotein is a strong causative agent. Therefore, by decomposing and removing this glycoprotein, it is possible to eliminate deposits firmly attached to the separation membrane of the membrane module and improve the clogging state of the separation membrane. Examples of microorganisms capable of degrading and removing glycoproteins include microorganisms belonging to the genus Bacillus and microorganisms belonging to the genus Bifidos that secrete at least a proteolytic enzyme or a carbohydrate degrading enzyme outside the cell.

  The microorganism that improves the clogging state of the separation membrane can also be obtained by screening a microorganism that secretes at least a proteolytic enzyme or a carbohydrate-degrading enzyme outside the cell from an existing group of microorganisms. For example, a microorganism having excellent protein degradability and carbohydrate degradability can be screened by the following simple enzyme activity test.

(1) Protein degradability A fungus is inoculated linearly on a plate of an agar culture medium containing casein at a concentration of 0.2 to 1.0%. The agar culture medium containing casein is opaque to translucent, but exhibits a protein degradability (has protein degradability) when a transparent band is formed around the colony of the fungus after the growth of the fungus.

(2) Carbohydrate degradability A fungus is linearly inoculated on a plate of an agar culture medium containing soluble starch at a concentration of 0.2 to 1.0% and cultured, and iodine solution is poured onto the plate after growth. If a transparent band that does not turn blue is formed around the colony of the fungus, it indicates starch degradability (has starch degradability).

  Specifically, the Bacillus methotrophicus CBMB205T (EU194897) strain, the Bacillus subtilis subsis subspis subbis subsisis subs.

  Further, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium minfantis, etc., which are bifidobacteria, can be used.

  The microorganisms described above can be cultured, stored, and separated by a method generally used for Bacillus or Bifidobacteria. For example, if the nutrient medium is mentioned, the medium such as Nutrient medium (0.3% meat extract, 0.5% peptone) or LB medium (0.5% yeast extract, 1% peptone, 1% sodium chloride) Culture can be performed.

In the wastewater treatment method of the present invention, microorganisms that improve the clogging state of the separation membrane are dominant. “Dominance” means that the number of the biota living in the treatment tank 1 is dominant. Whether it is dominant or not is determined by randomly identifying the biota living in the treatment tank 1 by determining the 16S rDNA sequence, etc. In addition, the percentage of microorganisms belonging to the genus species contained in the genus species is found by the simple enzyme activity test described above, etc. Can do. Specifically, about 1 × 10 ⁷ to 1 × 10 ¹⁰ bacteria are present in 1 mL of activated sludge in the treatment tank 1 for improving the clogging state of the separation membrane.

  The means for predominating the microorganism that improves the clogging state of the separation membrane in the treatment tank 1 is not particularly limited. For example, the Bacillus or Bifidobacterium exemplified above is used as an inoculum. As such, it is added to the seed sludge to be added, added to the waste water before flowing into the treatment tank 1, added to the waste water after flowing into the treatment tank 1, etc., and then the Bacillus bacteria and Bifidobacterium The method of maintaining the processing conditions in which the is maintained is mentioned. That is, by adding the above microorganisms to the initial stage of the wastewater treatment operation, it is possible to ensure that the number is dominant in the biota living in the treatment tank 1, and then the treatment conditions of the conventional method If this is maintained, microorganisms that improve the clogging state of the separation membrane are dominant during the treatment period. In addition, the surplus sludge obtained after dominating microorganisms that improve the clogging state of the separation membrane and performing wastewater treatment maintains the balance of the biota in which the microorganisms are dominated. Therefore, such excess sludge may be obtained from another wastewater treatment facility, and this may be added as seed sludge at the time of starting up the wastewater treatment facility to be newly treated. Alternatively, when the dominance of microorganisms that improve the clogging state of the separation membrane has diminished, such seed bacteria and seed sludge may be added as needed.

  The wastewater treatment condition may be performed according to the conventional method. Typically, for example, the concentration (MLSS) of the activated sludge in the treated wastewater in the treatment tank 1 is controlled in the range of 2000 mg / L to 2500 mg / L. The pH is preferably controlled in the vicinity of neutrality, that is, in the range of 6.5 to 7. In addition, treatments that utilize the activity of microorganisms that tend to prefer anaerobic conditions (denitrifying bacteria, dephosphorizing bacteria, denitrifying phosphorus-accumulating bacteria, etc.) and microorganisms that prefer aerobic conditions (nitrifying bacteria, yeast, The treatment for utilizing the activity of E. coli etc. may be carried out stepwise, continuously or intermittently in the treatment tank 1. In this case, although depending on the nitrogen concentration, the phosphorus concentration, etc. in the wastewater, the redox potential under anaerobic conditions is set in the range of −150 mV to −200 mV, and the dissolved oxygen amount under the aerobic conditions is 2.0 mg / L˜ It is preferable to manage so that it may become the range of 3.5 mg / L. For example, the wastewater treatment apparatus shown in FIG. 1 can be performed by adjusting the supply of air from the diffuser plate 5. However, in order to prevent ammonia, which is an odor component, from remaining in the wastewater that has been treated for a predetermined time in the treatment tank 1, the treatment is performed in an aerobic condition in which nitrifying bacteria act in the final process. It is preferable to finish the process.

  In the wastewater treatment method of the present invention, the activation treatment of microorganisms for improving the clogging state of the separation membrane is performed according to the clogging state of the separation membrane. The activation treatment can be performed, for example, by adding an iron compound such as an iron salt or a magnesium compound such as a magnesium salt to the wastewater treated with activated sludge in the treatment tank 1. This increases the secretion of proteolytic enzymes and carbohydrate-degrading enzymes that are secreted by the microorganisms outside the cells. Moreover, you may perform the activation process by adding silicon compounds, such as a silicate, to the waste_water | drain processed by the activated sludge in the processing tank 1. FIG. This activates the growth of the microorganism. The microorganism activation process may be a process including both of them.

  For example, in the wastewater treatment apparatus shown in FIG. 1, an activator containing at least an iron compound, a magnesium compound, and a silicon compound is stored in the activator supply tank 7, and the activator infusion pump 8 is used to store the activator in the treatment tank 1 when desired. Can be added. In this case, the content ratio of the total amount of iron compound and magnesium compound contained in the activator and the silicon compound is preferably 0.5 to 5: 1 in terms of mass, and more preferably 2: 1. . Moreover, it is preferable to add a silicon compound so that it may exist in the waste_water | drain in the processing tank 1 with the density | concentration of 0.1-2 mass% with respect to the BOD load of a processing tank, It is more preferable to add so that it may exist with the density | concentration of 0.2-1 mass%. In the case of an iron compound and a magnesium compound, it is preferable to add the waste water in the treatment tank 1 so as to exist at a concentration of 0.1 to 2% by mass with respect to the BOD load of the treatment tank. It is more preferable to add so that it may exist in the density | concentration of 0.4-2 mass% with respect to BOD load.

  The activator may contain other minerals in addition to the iron compound such as iron salt, magnesium compound such as magnesium salt, and silicon compound such as silicate. Examples include calcium compounds such as calcium salts, aluminum compounds such as aluminum salts, nickel compounds such as nickel salts, and titanium compounds such as titanium salts.

  In order to grasp the clogged state of the separation membrane, for example, it can be performed by measuring whether or not the water pressure of the treated water solid-liquid separated by the separation membrane is lower than a predetermined value. In other words, the separation membrane clogs with the progress of the wastewater treatment operation, and the membrane pressure rises, while the water pressure of the treated water solid-liquid separated by the separation membrane decreases, so that the water pressure is a predetermined threshold value. If it exceeds and falls below, it can be determined that it is time to eliminate clogging. In this case, it is preferable to perform measurement after applying a reverse water treatment from the treated water side opposite to that during steady operation to perform a backwash treatment of the separation membrane or a bubbling treatment of the separation membrane. According to this, since measurement is performed after removing impurities that are relatively weakly attached to the membrane module 2, the state of the clogging of the separation membrane can be grasped more accurately. For example, in the wastewater treatment apparatus shown in FIG. 1, the pressure of the treated water that has been solid-liquid separated by the separation membrane is monitored by a pressure sensor 10 provided in the middle of a pipe that communicates with the membrane module 2. . Further, the water pressure from the treated water side can be applied by reversing the suction direction by the suction pump 3.

  In order to grasp the clogging state of the separation membrane, in addition to using the water pressure of the treated water solid-liquid separated by the separation membrane as an index as described above, for example, the treated water separated by solid-liquid separation by the separation membrane is used. This can be done by measuring whether or not the amount of water per unit time falls below a predetermined value determined arbitrarily. That is, the separation membrane clogs with the progress of the wastewater treatment operation, and the membrane pressure increases, while the amount of treated water solid-liquid separated by the separation membrane decreases per unit time. When the amount of water per hit exceeds a predetermined threshold and falls below, it can be determined that it is time to eliminate clogging.

  FIG. 2 is a schematic configuration diagram showing another example of the waste water treatment apparatus for carrying out the waste water treatment method according to the present invention. This waste water treatment apparatus differs from the waste water treatment apparatus shown in FIG. 1 in that it includes another activator supply tank 11 in addition to the activator supply tank 7. Similar to the activator supply tank 7, an activator that improves the activity against microorganisms that improve the clogging state of the separation membrane by the activator injection pump 12 from the activator supply tank 11 is a treatment tank. It is supplied to the waste water in 1. A valve 13 is provided in the middle of the pipe, and the supply amount of the activator is adjusted by opening and closing the valve 13.

  In this embodiment, the activator can be added into the treatment tank 1 from two independent routes. For example, the iron compound and the magnesium compound can be introduced from the activator supply tank 11 while the silicon compound is introduced from the activator supply tank 7. According to this embodiment, the silicon compound such as silicate has low solubility and must be supplied as a suspension, and the handling of the iron compound and magnesium is slightly complicated in order to adjust the addition concentration. The compound can be supplied into the treatment tank 1 separately from the silicon compound such as silicate, without complicated handling. In addition, for example, when the number of microorganisms in the treatment tank 1 steadily shows a decreasing tendency, the silicon compound that activates the growth of microorganisms regardless of the clogging state is continued. At the time of adding and eliminating clogging, the amount of silicon compound added may be increased or only the iron compound and magnesium compound may be added.

(Wastewater treatment equipment)
The waste water treatment apparatus of the present invention measures the clogging state of the separation membrane and means for supplying a microbial activator for improving the clogging state of the separation membrane in order to extend the life of the separation membrane of the membrane module. And a control means for controlling the supply amount of the activator into the wastewater treated with activated sludge in the treatment tank.

  Referring to FIGS. 1 and 3, the activator supply tank 7 stores the activator, and from there, the activator injection pump 8 supplies the activator to the treatment tank 1. This constitutes the “means for supplying a microbial activator for improving the clogging state of the separation membrane” of the present invention. In addition, a pressure sensor 10 is provided in the middle of the pipe communicating with the membrane module 2 to monitor the water pressure of the treated water that has been solid-liquid separated by the separation membrane. This constitutes the “means for measuring the clogging state of the separation membrane” of the present invention. Furthermore, a control device 14 capable of receiving a signal corresponding to the water pressure value of the treated water in the pressure sensor 10 and transmitting a drive signal to the activator injection pump 8 or the valve 9 is provided. It constitutes “control means for controlling the amount of activator supplied into the wastewater treated with activated sludge in the treatment tank”.

  And when the water pressure value of the treated water in the pressure sensor 10 is inputted to the calculation unit 15 of the control device 14 and compared with an arbitrarily determined predetermined value stored in the calculation unit 15, it falls below that value. Determines that it is time to eliminate clogging (FIG. 3). Then, a signal corresponding to the determination drives the activator infusion pump 8 or increases its driving amount through the output unit 16, or opens the valve 9 or increases its opening amount ( FIG. 3). Thereby, based on the clogged state of the separation membrane, the activator can be supplied into the processing tank 1 or the supply amount thereof can be increased. The supply of the activator is continued until the water pressure value of the treated water in the pressure sensor 10 is compared with an arbitrarily determined predetermined value stored in the calculation unit 15 of the control device 14 and exceeds that value. Alternatively, it may be finished in a predetermined time.

  2 and FIG. 4, this waste water treatment apparatus is provided with another activator supply tank 11 in addition to the activator supply tank 7, and the first from the activator supply tank 7. 1 is different from the waste water treatment apparatus shown in FIG. 1 in that the supply amount of the second active agent and the supply amount of the second active agent from the active agent supply tank 11 can be independently controlled by the control device 14. In this aspect, the water pressure value of the treated water in the pressure sensor 10 is input to the first calculation unit 17 of the control device 14 and compared with an arbitrarily determined predetermined value stored in the calculation unit 17. If it is below the value, it is determined that it is time to eliminate clogging (FIG. 4). A signal corresponding to the determination drives the activator infusion pump 8 or increases its driving amount through the first output unit 18 or opens the valve 9 or increases its opening amount. (Fig. 4). On the other hand, a signal corresponding to the water pressure value of the treated water in the pressure sensor 10 is also input to the second calculation unit 19 of the control device 14 and is compared with an arbitrarily determined predetermined value stored in the calculation unit 19. If it is below that value, it is determined that it is time to eliminate clogging. A signal corresponding to the determination drives the activator infusion pump 12 through the second output unit 20 or increases its driving amount, or opens the valve 13 or increases its opening amount. (Fig. 4). Thereby, based on the clogging state of the separation membrane, the first activator from the activator supply tank 7 can be supplied into the processing tank 1 or the supply amount thereof can be increased, and independently of that. In addition, the second activator from the activator supply tank 11 can be supplied into the processing tank 1 or its supply amount can be increased. The supply of the first activator from the activator supply tank 7 is such that the water pressure value of the treated water in the pressure sensor 10 is an arbitrarily determined predetermined value stored in the first calculation unit 17 of the control device 14. The comparison may be continued until the value becomes equal to or greater than the value, or may be terminated in a predetermined time. In addition, the second activator is supplied from the activator supply tank 11 in such a way that the water pressure value of the treated water in the pressure sensor 10 is an arbitrarily determined predetermined value stored in the second calculation unit 19 of the control device 14. The comparison may be continued until the value becomes equal to or greater than the value, or may be terminated in a predetermined time.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited by these examples.

<Test Example 1>
Bacillus methylotropicus (hereinafter referred to as “Bacillus strain A”), a bacterium belonging to the genus Bacillus, was inoculated into a Nutrient medium and cultured at 30 ° C. overnight. At this time, an activator (a mineral containing silicate) that improves the activity of Bacillus bacteria, an iron salt added to the activator to increase the iron salt content by a factor of 2, and a magnesium salt as the activator To increase the magnesium salt content by a factor of 2, adding manganese salt to the active agent to increase the manganese salt content to a double amount, adding calcium salt to the active agent The calcium salt content increased by a factor of 2 was added to the culture medium at 2 mg / mL and cultured, and the proteolytic enzyme activities secreted into the culture were compared.

  The proteolytic activity was measured by filtering the above culture solution through a filter having a pore size of 0.2 μm, and using the filtrate in a fluorescent proteolytic enzyme assay kit (Thermo Fisher Scientific). In this kit, the fluorescence intensity increased due to the presence of the proteolytic enzyme, and the measured fluorescence intensity was divided by the absorbance at 600 nm representing the cell concentration, and compared as the protease activity per unit cell concentration.

  As a result, as shown in FIG. 5, when the content of the iron salt or magnesium salt in the active agent is increased to twice the usual amount, proteolysis of Bacillus strain A is achieved as compared with the case where the conventional active agent is used. Enzyme activity increased. On the other hand, when the content of the manganese salt in the activator was increased to twice the usual amount, the protease activity of Bacillus strain A decreased compared to the case where the conventional activator was used. When the content of the calcium salt in the active agent was increased to twice the usual amount, the protease activity was the same as when the conventional active agent was used.

<Test Example 2>
About Bacillus strain A, the amylolytic enzyme activity secreted in each culture solution cultured like Test Example 1 was investigated.

  Specifically, the culture broth was filtered through a filter having a pore size of 0.2 μm, 3 mL of 0.5% water-soluble starch was added to 1 mL of the filtrate, and an iodine solution was added dropwise after 60 minutes. If starch remains, it exhibits a blue-violet color characteristic of iodine starch reaction, and if starch is decomposed, it does not change color. The color was measured by absorbance at 550 nm.

  As a result, as shown in FIG. 6, when the content of iron salt, magnesium salt or calcium salt in the active agent is increased to twice the usual amount, the Bacillus strain A is compared with the case where the conventional active agent is used. Increased amylolytic enzyme activity. On the other hand, when the content of the manganese salt in the activator was increased to twice the usual amount, the amylolytic enzyme activity of Bacillus strain A was reduced as compared with the case where the conventional activator was used.

<Test Example 3>
Bacillus sp. Closely related to the Bacillus subtilis of the genus Bacillus. (Hereinafter referred to as “Bacillus strain B”) was tested in the same manner as in Test Example 1.

  As a result, as shown in FIG. 7, when the content of iron salt or magnesium salt in the active agent is increased to twice the usual amount, proteolysis of Bacillus strain B is achieved as compared with the case where the conventional active agent is used. Enzyme activity increased. On the other hand, when the content of the manganese salt or calcium salt in the activator was increased to twice the usual amount, the protease activity of Bacillus strain B decreased compared to the case where the conventional activator was used.

<Test Example 4>
For Bacillus strain B, the same test as in Test Example 2 was performed.

  As a result, as shown in FIG. 8, when the content of iron salt or magnesium salt in the active agent is increased to twice the usual amount, starch degradation of Bacillus strain B can be achieved as compared with the case where the conventional active agent is used. Enzyme activity increased. On the other hand, when the content of manganese salt or calcium salt in the active agent was increased to twice the usual amount, the amylolytic enzyme activity of Bacillus strain B was reduced as compared with the case where the conventional active agent was used.

  From the results of Test Examples 1 to 4, the active agent consisting of a mineral containing a silicate conventionally used as an activator for improving the activity of Bacillus bacteria, the iron salt and the magnesium salt of the mineral content It has been clarified that the effect of improving the enzymatic activity of Bacillus bacteria is particularly high by increasing the secretion of proteolytic enzymes and carbohydrate-degrading enzymes secreted by Bacillus bacteria outside the cells. On the other hand, it has been clarified that the manganese salt in the mineral content of the active agent has a particularly high effect of inhibiting the enzyme activity of Bacillus bacteria. Conventionally, it has been known that silicate among the mineral content of the active agent has an effect of assisting the growth of Bacillus bacteria. Therefore, it became clear that the activation process of Bacillus bacteria can be performed efficiently by individually optimizing the addition amount of these minerals added as the activator.

1: treatment tank 2: membrane module 3: suction pump 4: sludge extraction pump 5, diffuser plate 6: blower 7, 11: activator supply tank 8, 12: activator injection pump 9, 13: valve 10: pressure sensor 14: Control device 15: Calculation unit 16: Output unit 17: First calculation unit 18: First output unit 19: Second calculation unit 20: Second output unit

Claims (9)

A wastewater treatment method in which wastewater containing organic matter is introduced into a treatment tank to perform activated sludge treatment, and the wastewater after activated sludge treatment is separated into solid and liquid by a separation membrane installed in the treatment tank, and the treated water is taken out. Improving the clogging state of the separation membrane, predominating the microorganisms belonging to the genus Bacillus, and indicating the clogging state of the separation membrane as a water pressure or amount of treated water solid-liquid separated by the separation membrane Then, based on the measured value , as an activation treatment of the microorganism, a treatment of adding an iron compound and / or a magnesium compound to wastewater treated with activated sludge in the treatment tank is performed. Wastewater treatment method. Before when measured value of Kisui pressure or water falls below a predetermined value, the waste water treatment method according to claim 1, wherein performing the activation treatment of said microorganism. The wastewater treatment method according to claim 1 or 2, wherein the microorganism that improves the clogged state of the separation membrane includes a microorganism that secretes at least a proteolytic enzyme or a carbohydrate degrading enzyme to the outside of the cell. The wastewater treatment method according to any one of claims 1 to 3 , wherein the activation treatment of the microorganism is a treatment including an increase in a proteolytic enzyme and / or a carbohydrate degrading enzyme secreted by the microorganism outside the cell. The wastewater treatment method according to any one of claims 1 to 4 , wherein the activation treatment of the microorganism includes a treatment of further adding a silicon compound to wastewater to be treated with activated sludge in the treatment tank. The wastewater treatment method according to any one of claims 1 to 5 , wherein the state of clogging of the separation membrane is measured after backwashing or bubbling of the separation membrane. A wastewater treatment apparatus that introduces wastewater containing organic substances into a treatment tank to perform activated sludge treatment, and separates the wastewater after activated sludge treatment with a separation membrane installed in the treatment tank, and takes out the treated water. ,
A means for supplying an activator of a microorganism belonging to the genus Bacillus, which improves the clogging state of the separation membrane, and comprising at least an iron compound or a magnesium compound;
Means for measuring the clogging state of the separation membrane using as an index the water pressure or amount of treated water solid-liquid separated by the separation membrane ;
A wastewater treatment apparatus comprising control means for controlling a supply amount of the activator into wastewater to be treated with activated sludge in the treatment tank based on the measured value . The wastewater treatment apparatus according to claim 7, wherein the microorganism that improves the clogging state of the separation membrane is a microorganism that secretes at least a proteolytic enzyme or a carbohydrate degrading enzyme to the outside of the microbial cell. Activator of the microorganisms is further waste water treatment apparatus according to claim 7 or 8 Symbol mounting comprising a silicon compound.