JP2007275833A - Microorganism treatment method and device for waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microorganism treatment method and device for waste water where biological treatment for organic matter is performed at a low concentration, so as to reduce the amount of surplus sludge, thus the reduction of treatment cost and running cost for surplus sludge is made possible, and further, a sludge load for the biological treatment is made high, thus the miniaturization of the device and the reduction of cost are made possible. <P>SOLUTION: Raw water W1 is made to flow into a low concentration reaction tank 3 provided at a purification treatment system, further, microorganisms of decomposing sludge are replenished only by the amount to be required via an organism replenishment system 5, and, while activated sludge concentration (MLSS) is held to the low concentration of ≤1,000 mg/L, the sludge in the raw water W1 is aerated, so as to be decomposed by biological treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, raw water such as industrial wastewater and domestic wastewater containing organic pollutants generated in kitchens, etc. is purified by biological treatment of microorganisms and released into sewers or general rivers that meet discharge standards. The present invention relates to a method and apparatus for treating microbial wastewater.

  For microbial treatment of this type of wastewater, raw water tanks, aeration tanks, sedimentation tanks, treated water tanks, sludge storage tanks, etc. are provided in the purification treatment system, and the wastewater flowing into the raw water tanks is pumped into the aeration tanks and aerated in the aeration tanks. The clarified supernatant is obtained by decomposing organic matter, etc. by the catalytic oxidation action of microorganisms that are introduced from the inside or outside while being transferred to the settling tank, and in the settling tank, the liquid is separated by gas-liquid separation by gravity sedimentation of activated sludge. Water is transferred to the treated water tank, and the purified treated water is discharged into the sewer or river through the treated water tank.

  In addition, some of the sediment containing activated sludge that has settled in the sedimentation tank is returned to the aeration tank as return sludge and reused for decomposition of organic matter, etc., and the rest is transferred to the sludge storage tank as surplus sludge. After processing such as concentration and dehydration in the sludge storage tank, it is transferred to an industrial waste treatment facility and disposed of by incineration. Purified treated water discharged from the treated water tank is discharged into rivers or sewers. To do.

Furthermore, various proposals including the prior art disclosed in Patent Documents 1 to 4, for example, have been made regarding reduction (volume reduction) of excess sludge in microbial treatment of wastewater.
JP 2005-349252 A JP 2005-279351 A JP 2004-141802 A JP 2000-051886 A

  In the prior art, unless the activated sludge concentration (MLSS) containing microorganisms is increased, the purification treatment ability by microorganisms performed in an aeration tank or the like cannot be sufficiently exerted, and the activated sludge is aggregated in the sedimentation tank to obtain a supernatant. The activated sludge concentration (MLSS) is set to a high concentration of about 3000 to 5000 mg / L, for example, so as to increase the reaction rate by microorganisms.

  However, when the activated sludge concentration is increased, microorganisms gradually grow to generate a large amount of excess sludge, and if the aeration tank is enlarged and not sufficiently diffused, it will die due to lack of oxygen. Decreases the degradation capacity of organic matter, but a large amount of money is required to dispose of a large amount of excess sludge. Therefore, in order to solve these problems, proposals relating to the reduction (volume reduction) of excess sludge disclosed in Patent Documents 1 to 4 and the like have been made.

  Similar to the prior arts disclosed in Patent Documents 1 to 4, the present invention mainly aims to reduce excess sludge in the microbial treatment of wastewater. By reducing the volume (volume reduction) of surplus sludge by conducting biological treatment of organic matter at a low concentration, it is possible to reduce surplus sludge treatment costs and running costs, and increase the sludge load for biological treatment Accordingly, the present invention provides a microbial treatment method and apparatus for wastewater that enables downsizing and cost reduction of the apparatus.

  The microbial treatment method for wastewater according to the present invention allows raw water to flow into a low-concentration reaction tank provided in a purification treatment system, and microorganisms that decompose pollutants replenish only a necessary amount via a biological replenishment system. While maintaining the concentration (MLSS) at a low concentration of 1000 mg / L or less, the pollutants in the raw water are aerated and decomposed by biological treatment. (Claim 1)

  The microbial treatment apparatus for wastewater according to the present invention is an apparatus for carrying out the method of claim 1 and a microbial culture branched from the raw water tank and connected to a purification treatment system comprising a low concentration reaction tank connected to the raw water tank. A biological replenishment system was provided for high concentration treatment in the tank and circulating the increased microorganisms to the low concentration reaction tank. (Claim 2)

  The microbial treatment apparatus for wastewater according to the present invention is an apparatus for carrying out the method of claim 1, and is connected to a raw water tank for primary treatment by being connected to a raw water tank, and to a downstream side of the low concentration reaction tank. A purification treatment system provided with an aeration tank and a sedimentation tank for performing a secondary treatment, and a biological replenishment system for circulating a part of excess sludge from the sedimentation tank to a low-concentration reaction tank were provided. (Claim 3)

  In the microbial treatment method of wastewater according to claim 1, it is necessary to increase the sludge load by restricting the accumulation of excess activated sludge and the growth of microorganisms in the low-concentration reaction tank, and to decompose organic matter. By supplying an appropriate amount of microorganisms from the bioreplenishment system and maintaining a low concentration, at least 70% or more of the pollutant can be decomposed.

  Therefore, since the generation of surplus sludge that settles can be suppressed, the surplus sludge can be reduced (volume reduction) to easily and inexpensively dispose of it, and even with a small amount of oxygen supplied in a small reaction tank. Since decomposition processing is possible, it can contribute to size reduction and cost reduction of the apparatus.

  In addition to the above-described operation and effect of claim 1, the microbial treatment apparatus for wastewater according to claim 2 adopts a form in which the majority of the purification treatment system is composed of only a low concentration reaction tank and the aeration tank and the precipitation tank are omitted. As a result, it is possible to reduce running costs, reduce the size and cost of the equipment, and use nutrients in the raw water to grow in a microbial culture tank and circulate in a low-concentration reaction tank, thus reducing habitats. Acclimatized microorganisms can be activated to increase degradation capacity.

  In the microbial treatment apparatus for wastewater according to claim 3, in addition to the above-mentioned action and effect according to claim 1, the primary purified water obtained by performing the primary treatment in the low concentration reaction tank to decompose at least 70% of the pollutant, Since the water quality is further purified in the aeration tank and the sedimentation tank, the treatment in the aeration tank and the precipitation tank becomes easier and the running cost is reduced and the apparatus is smaller than the purification system provided with the prior art aeration tank and the precipitation tank. And cost reduction.

  DETAILED DESCRIPTION OF THE INVENTION A method and apparatus for treating microorganisms of wastewater according to the present invention will be described in detail with reference to the accompanying drawings showing a preferred embodiment to which the present invention is applied. FIG. 1 is a first example to which the present invention is applied. FIG. 2 is a schematic configuration diagram showing a microbial treatment apparatus 1A having a configuration in which treated water W2 purified from raw water W1 is discharged into a sewer. FIG. 2 is a second embodiment, and treated water W3 purified from raw water W1 is treated as a river. The microorganisms processing apparatus 1B by the form discharged | emitted is shown with a typical block diagram.

  The microbial treatment apparatus 1A includes a purification system using a raw water tank 2, a low-concentration reaction tank 3, and a treated water tank 4 connected in series, and a microorganism culture tank 5 branched from the raw water tank 2 and connected in parallel. The raw water W1 that is provided with a biological replenishment system by the chamber 5A and contains organic pollutants generated in the kitchen or the like and that is made up of industrial wastewater or domestic wastewater flows into the raw water tank 2 through the pipe L1 and is stored therein, and then the pump P1 , P2 and transferred to the low-concentration reaction tank 3 of the purification treatment system via the pipe L2 and transferred to the microorganism culture tank 5 of the biological supply system via the pipe L3.

  The raw water W1 contains activated sludge of organic or inorganic substances, and the flow rate transferred from the raw water tank 2 to the low-concentration reaction tank 3 of the purification treatment system and the microorganism culture tank 5 of the biological supply system is a predetermined distribution ratio. The flow rate can be controlled so that the distribution ratio can be finely adjusted as necessary, and a flow meter (not shown) is provided in the pipe L2 to be transferred to the low concentration reaction tank 3. Is set so that, for example, about 1/5 thereof is transferred to the microorganism culture tank 5.

  The low-concentration reaction tank 3 is provided with aeration means (not shown) such as an ultrafine bubble diffuser as in the case of the aeration tank in the prior art, and promotes the catalytic oxidation action of microorganisms by aeration. The organic matter is decomposed, but the difference from the conventional aeration tank is that the activated sludge concentration (MLSS) is lowered and the organic matter is decomposed in a state where the number of microorganisms is limited. An appropriate amount of microorganisms is secured from the microorganism culture tank 5 via the pump P3 and the pipe L4 while supplying the shortage.

  In this regard, in the prior art, if the activated sludge containing microorganisms is not sufficiently present in the aeration tank, the purification treatment capacity cannot be sufficiently exhibited. Therefore, the activated sludge concentration (MLSS) in the aeration tank is, for example, 3000 to 5000 mg / L. Although the reaction rate by microorganisms was increased by increasing the concentration to such a level, when the activated sludge concentration is increased, the microorganisms gradually grow to generate a large amount of excess sludge.

  Therefore, in the low-concentration reaction tank 3, the amount of raw water W1 pumped from the raw water tank 2 is measured while flowing with the flow meter so that the activated sludge concentration (MLSS) is maintained at a low concentration of 1000 mg / L or less. The activated sludge containing microorganisms necessary for the decomposition treatment of the organic matter with respect to the raw water W1 is replenished from the microorganism culture tank 5 in an appropriate amount that does not become excessive, and these microorganisms are mixed with the supernatant water of the low concentration reaction tank 3 and Together with this, it is possible to replenish microorganisms flowing out into the treatment water tank 4, thereby ensuring a low activated sludge concentration (MLSS) and a microorganism concentration.

  In this way, the accumulation of excess activated sludge and the growth of microorganisms in the low-concentration reaction tank 3 are restricted to increase the sludge load, and an appropriate amount of microorganisms necessary for the decomposition treatment of organic matter is removed by microorganisms. By replenishing from the culture tank 5 and maintaining a low concentration, it is possible to decompose at least 70% of the pollutant and suppress the generation of surplus sludge that settles. Since the volume can be reduced and the disposal process can be easily and inexpensively performed, and the decomposition process can be performed with a small amount of oxygen supplied in a small reaction tank, the apparatus can be reduced in size and cost.

  The supernatant water purified by the decomposition treatment in the low-concentration reaction tank 3 flows into the treated water tank 4 through the pipe L5, and the supernatant water in which the microorganisms are precipitated from the microorganism culture tank 5 in the settling chamber 5A is piped L4. In this case, in the case of the microorganism treatment apparatus 1A according to the first embodiment, the treated water W2 is discharged into a general river. It is assumed that it is discharged into the sewer instead of being purified to the extent possible, and some microorganisms are mixed and discharged into the treated water W2.

  In order to maintain an environment in which microorganisms can grow in the microorganism culture tank 5, culture water containing activated sludge containing microorganisms is stored in advance in the tank, and ultrafine bubbles are contained in the tank. Aeration means (not shown) such as an air diffuser of a type is provided, and the contact oxidation action of microorganisms is promoted by aeration so that the decomposition of organic matter and the growth of microorganisms are performed, and a pipe L3 is provided there. For example, a part of the raw water W1 is allowed to flow in at a distribution ratio of about 1/5 of the flow rate sent to the low concentration reaction tank 3.

  In the microorganism culturing tank 5, the organic matter is decomposed and the microorganisms are propagated. Accordingly, the pump P3 and the pipe L4 are measured while measuring the activated sludge containing microorganisms from the surplus settled sludge with a flow meter (not shown). The appropriate amount (for example, about 1/10 of all microorganisms in the low-concentration reaction tank 3) is transferred to the low-concentration reaction tank 3 through The necessary amount of activated sludge and the amount of microorganisms are ensured, and surplus flows into the sedimentation chamber 5A, and the supernatant is transferred to the treated water tank 4 via the pipe L6.

  In particular, in the microorganism culture tank 5, microorganisms are propagated by nutrients contained in the raw water W <b> 1 supplied from the raw water tank 2, and microorganisms in a state acclimatized to the sludge environment to be decomposed are contained in the low concentration reaction tank 3. Since it is circulated in the raw water W1 and used for the decomposition of organic matter in the low-concentration reaction tank 3, it is possible to increase the ability to decompose organic matter compared to the case where microorganisms are simply supplied from the outside. In addition, the input amount of microorganisms is adjusted to the low-concentration reaction tank 3 in accordance with the consumption amount that decreases due to outflow or the like.

  In the microorganism treatment apparatus 1A according to the first embodiment illustrated in FIG. 1, a microorganism culture tank 5 for supplying activated sludge containing microorganisms to the low concentration reaction tank 3 is connected to the raw water tank 2, and the raw water W1. The microorganisms are allowed to grow in the microorganism culture tank 5 due to the nutrients contained therein. The microorganism culture tank 5 is separated from the raw water tank 2, and the microorganisms and nutrients are introduced into the microorganism culture tank 5 from the outside to be propagated. It is also possible to take a form in which the microorganisms are replenished to the low concentration reaction tank 3.

  Next, the microorganism treatment apparatus 1B according to the second embodiment eliminates the microorganism culture tank 5 branched and connected from the raw water tank 2 in the first embodiment, and decomposes the low concentration reaction tank 3 of the purification treatment system. The biological replenishment system for replenishing the necessary microorganisms takes a form of reflux from the rear side of the purification treatment system, and the purification treatment system is provided with the low concentration reaction tank 3 as in the case of the first embodiment. In the subsequent stage, an aeration tank 6 and a precipitation tank 7 having the same configuration as in the case of the prior art are connected, but the same components as those in the microorganism treatment apparatus 1A of the first embodiment are denoted by the same reference numerals. Detailed description will be omitted.

  In the microorganism treatment apparatus 1B, the raw water W1 flowing into and stored in the raw water tank 2 through the pipe L1 is pumped up by the pump P1, transferred to the low concentration reaction tank 3 through the pipe L2, and is stored in the low concentration reaction tank 3. Replenishment of microorganisms necessary for the decomposition treatment is performed by drawing out a necessary amount of concentrated sludge containing activated sludge from the settling tank 7 and returning it through the pipes L8 and L9, and aerating the microorganisms while aerating by aeration means. Then, the organic substance is decomposed (primary treatment), and the primary purified water by the supernatant water purified by the primary treatment is transferred to the aeration tank 6 through the pipe L10.

  In this primary treatment, an appropriate amount of activated sludge and microorganisms necessary for the decomposition treatment of organic matter are set so as to increase the sludge load by restricting the accumulation of excess activated sludge and the growth of microorganisms in the low-concentration reactor 3. It is possible to decompose at least 70% or more of the pollutant while maintaining the low concentration by replenishing by returning from the sedimentation tank 7, and it is possible to suppress the generation of surplus sludge that settles. Since the sludge can be reduced in volume and can be disposed of easily and inexpensively, and it can be decomposed with a small amount of oxygen supplied in a small reaction tank, it can contribute to downsizing and cost reduction of the apparatus. .

  In the aeration tank 6 and the sedimentation tank 7, secondary treatment is performed on the primary purified water transferred from the low-concentration reaction tank 3, and the aeration tank 6 is provided with aeration means (illustrated) such as an ultrafine bubble diffuser. In addition, the activated sludge and microorganisms necessary for the decomposition treatment of the organic matter are transferred to the sludge containing the activated sludge extracted from the settling tank 7 by a necessary amount through the pipes L8 and L11. It is replenished, the organic matter is decomposed by microorganisms while aeration, and the purified supernatant water is transferred to the sedimentation tank 7 through the pipe L12.

  In addition, the sedimentation tank 7 performs gas-liquid separation by gravity sedimentation of activated sludge, and the purified supernatant water is transferred to the treated water tank 4 via the pipe L13, and the excess sludge that has settled and concentrated at the bottom is a low concentration reaction tank. 3 and the return to the aeration tank 6, except for the timely discharge to the outside and disposal as in the case of the prior art, but at least 70% or more of the pollutants are decomposed by the primary treatment in the low concentration reaction tank 3 Since it is treated, the secondary treatment can be performed by the aeration tank 6 and the sedimentation tank 7 which are small in size and have a small amount of aeration, and the decomposition treatment capacity for the organic matter is reduced, or a large amount of excess sludge is produced. It can be eliminated.

  Since the supernatant water purified by the secondary treatment by the aeration tank 6 and the sedimentation tank 7 flows into the treated water tank 4 through the pipe L13, the treated water W3 after the foreign matter is settled from the supernatant water is discharged. Although it discharges | releases to the drainage channel suitable for a reference | standard through the pipe L7, in the case of the microorganisms processing apparatus 1B by this 2nd Example, it can purify | clean to the extent which can be discharged to a general river.

  In the microorganism treatment apparatus 1B according to the second embodiment shown in FIG. 1, the primary purified water primarily treated by the low-concentration reaction tank 3 is secondary to the aeration tank 6 and the precipitation tank 7 provided separately. Although the treatment is performed, it is also possible to adopt a form in which an aeration / precipitation tank in which the aeration tank 6 and the precipitation tank 7 are integrally formed is provided, and in that case, an aeration means is provided in the aeration / precipitation tank. The aeration is stopped at an appropriate time interval by a timer or the like so that the sludge is settled and the supernatant water is discharged.

  As described above, in the microorganism treatment apparatuses 1A and 1B according to the first and second embodiments, the low concentration reaction tank 3 is provided in the purification treatment system, and the sludge of the raw water W1 pumped from the raw water tank 2 is provided in the low concentration reaction tank 3. The amount of microorganisms necessary for the decomposition treatment of the organic matter against the sludge is measured by the flowmeter, and the microorganisms in the microorganism culture tank 5 (first embodiment) or the sedimentation tank 7 (second embodiment) are used. The activated sludge in which microorganisms are grown in the replenishment system is replenished, and the activated sludge concentration (MLSS = microorganism concentration) is maintained at a constant low concentration of 1000 mg / L or less.

  That is, in the low concentration reaction tank 3, a low concentration inhabiting the minimum necessary microorganisms suitable for the decomposition treatment of the organic matter so that the microorganisms are not grown by excess activated sludge or the microorganisms are not killed by lack of oxygen. The organic matter in the raw water W1 is biologically treated to decompose at least 70% or more of the pollutants to purify the water quality, and the decrease in microorganisms flowing out to the subsequent stage together with the supernatant purified water An appropriate amount is replenished from the tank 5 or the sedimentation tank 7 side, and the amount of raw water W1 inflow relative to the volume of the low-concentration reaction tank 3 and the amount of microorganisms charged are controlled so that the decrease amount of microorganisms and the replenishment amount become equal. Are managed.

  In this way, when the concentration of the reaction tank for decomposing organic matter with microorganisms is lowered (using the low-concentration reaction tank 3), the environment inhabiting the microorganisms is stabilized and the organic matter is decomposed by the catalytic oxidation action. It is possible to activate and suppress the generation of surplus sludge that settles by increasing the decomposition treatment capacity, so that the surplus sludge can be reduced in volume and can be disposed of easily and inexpensively, and in a small reactor Since the decomposition process is possible even with an oxygen supply amount, it is possible to contribute to downsizing and cost reduction of the apparatus.

  In particular, as in the first embodiment, the low-concentration reaction tank 3 is used for the purification treatment system, and the aeration tank and the precipitation tank are omitted. In addition, microorganisms are cultured in the bioreplenishment system to replenish the low-concentration reaction tank 3. In the case of adopting the form of the microbial treatment apparatus 1A provided with the microbial culture tank 5, the biological treatment of only the low-concentration reaction tank 3 decomposes at least 70% or more of the pollutant with respect to the raw water W1 containing organic matter. Therefore, the water quality can be purified and discharged into the sewer, so that the running cost can be reduced and the apparatus can be reduced in size and price.

  Moreover, while providing the aeration tank 6 and the precipitation tank 7 similar to a prior art like 2nd Example, the form of the microorganism treatment apparatus 1B which performs a primary process using the low concentration reaction tank 3 in the front | former stage side of these is used. In the case of collecting, the primary treatment is performed in the low-concentration reaction tank 3, and at least 70% or more of the pollutants are decomposed to purify the water quality. Since it can be discharged, the treatment in the aeration tank and the sedimentation tank becomes easier compared to the purification system provided with the aeration tank and the precipitation tank in the prior art, and the running cost can be reduced and the apparatus can be reduced in size and price. it can.

  As is clear from the above examples, in the prior art, unless the concentration of activated sludge containing microorganisms is at least 1000 mg / L or more, the purification treatment ability by microorganisms cannot be exhibited in the aeration tank, and activated sludge in the sedimentation tank. The activated sludge concentration (MLSS) is set to a high concentration of about 3000 to 5000 mg / L, for example, to increase the reaction rate by microorganisms. In the low-concentration reaction tank 3 of the microbial treatment apparatus 1A, 1B according to the first and second embodiments, the idea of this prior art is changed to perform biological treatment of organic matter at a low concentration, thereby solving the problems of the prior art. did.

The typical block diagram of the microorganisms processing apparatus by the 1st Example to which this invention is applied is shown. The typical block diagram of the microorganisms processing apparatus by the 2nd Example to which this invention is applied is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microorganism processing apparatus 1A (according to the first embodiment) Microorganism processing apparatus 1B (according to the second embodiment) Microorganism processing apparatus 2 Raw water tank 3 Low concentration reaction tank 4 Treated water tank 5 Microorganism culture tank 5A, 7 Precipitation tank 6 Aeration Tank L1-L13 Piping P1-P3 Pump W1 Raw water W2, W3 Treated water

Claims (3)

  The raw water is allowed to flow into a low-concentration reaction tank provided in the purification treatment system, and microorganisms that decompose the pollutants are replenished only through the biological replenishment system, and the activated sludge concentration (MLSS) is 1000 mg / L or less. A method for microbial treatment of wastewater, characterized by aeration of pollutants in raw water and decomposition by biological treatment while maintaining a low concentration.   An apparatus for carrying out the method according to claim 1, wherein a high concentration treatment is performed in a purification treatment system having a low-concentration reaction tank connected to the raw water tank and a microorganism culture tank branched from the raw water tank and connected to the microorganism. A microbial treatment apparatus for wastewater, characterized in that a biological replenishment system for circulating the water in a low-concentration reaction tank is provided.   It is an apparatus which implements the method of Claim 1, Comprising: The low concentration reaction tank which performs a primary process by connecting to a raw | natural water tank, The aeration tank and the precipitation tank which connect to the back | latter stage side of a low concentration reaction tank, and perform a secondary process And a biological replenishment system for circulating a part of the excess sludge from the sedimentation tank to the low-concentration reaction tank.

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