JP2007283249A - Organic wastewater treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological treatment technique of organic wastewater capable of further reducing a production quantity of sludge and capable of further reducing the quantity of heat required in the adjustment of the temperature of organic wastewater. <P>SOLUTION: Organic wastewater is subjected to solid-liquid separation in a first sedimentation tank 1 while the liquid drawn out of the bottom part of the first sedimentation tank 1 is treated with thermophilic bacteria in a high-temperature treatment tank 2 and the thermophilic bacteria treated liquid discharged from the high-temperature treatment tank 2 is subjected to solid-liquid separation in a second sedimentation tank 3. The supernatant liquids of the first and second sedimentation tanks 1 and 3 are supplied to a biological treatment tank 4 for biological treatment and the liquid drawn out of the bottom part of the second sedimentation tank 3 is returned to the second sedimentation tank 3 while the biologically treated liquid discharged from the biological treatment tank 4 is subjected to solid-liquid separation in a third sedimentation tank 5 and the liquid drawn out of the bottom part of the third sedimentation tank 5 is returned to the biological treatment tank 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for treating organic wastewater with microorganisms.

  The activated sludge method of treating organic wastewater with activated sludge containing aerobic microorganisms has advantages such as high purification capacity and relatively low treatment costs. For this reason, various water treatment methods using the activated sludge method have been proposed and widely used in wastewater treatment such as sewage treatment and industrial wastewater treatment.

In the activated sludge method, various organic wastewaters to be treated are guided to an aeration tank (aeration tank), and in this aeration tank, organic matter in wastewater indicated by BOD (biochemical oxygen demand) is indicated by activated sludge. Purify treatment by decomposing pollutant components. The activated sludge method is usually carried out under conditions of a load amount expressed by BOD of about 0.3 to 0.8 kg / m ³ · day. For this reason, in order to process a large amount of organic waste water, there exists a tendency for an installation to enlarge, for example, the large aeration tank which requires a large site area is needed.

  Further, in the activated sludge method, 50 to 70% of the decomposed load amount is consumed as microbial maintenance energy, but the remaining 30 to 50% is used for the growth of bacterial cells, so the amount of activated sludge Will gradually increase. For this reason, in general, wastewater treated in the aeration tank is guided to the settling tank, and only the amount necessary for the purification treatment of organic wastewater is returned from the precipitated activated sludge to the aeration tank. The activated sludge other than is treated as surplus sludge through steps such as concentration, digestion, dehydration, composting, and incineration. For this reason, such processing is costly and troublesome, which is a problem.

  For this reason, as a treatment method in which sludge is not generated as much as possible, a large amount of sludge is retained in the reaction tank by a long-time aeration method in which the sludge residence time in the aeration tank is increased, or by attaching sludge to the surface of the contact material. A catalytic oxidation method or the like has been proposed and put into practical use (for example, see Non-Patent Document 1).

  However, these methods require a large installation area as an aeration tank in order to increase the sludge residence time in the aeration tank. In a long-time aeration tank, sludge is diffused when the load is reduced, which may impede solid-liquid separation. Also, the contact oxidation method is not preferred because sludge clogging may occur when the load increases.

  Therefore, it is conceivable to increase the residence time of the liquid to be treated in the activated sludge treatment tank corresponding to the increase in BOD load due to the solubilization treatment, that is, to increase the volume of the activated sludge treatment tank. Equipment costs will increase.

  On the other hand, Patent Document 1 discloses that organic waste water (raw water) is treated with bacteria (mainly by dispersal bacteria) to oxidize and decompose organic matter in the waste water and convert it into non-aggregating bacteria. It has been proposed to improve the efficiency of biological treatment by allowing the adherent protozoa to prey and remove the non-aggregating bacteria. In Patent Document 1, when the above method is used, it is possible to operate in a high load state, the treatment efficiency by the activated sludge method is remarkably improved, and further, the efficiency of biological treatment can be improved, and at the same time, surplus sludge is generated. It is described that the amount can be reduced.

However, as a result of research conducted by the present inventor using the above-described method, it has been found that the above-described effect may not be obtained unless the BOD concentration of the influent wastewater is about 600 mg / L or more. This is presumably because bacteria that inhabit at high temperatures are very active and require a large amount of nutrients, and when the influent wastewater concentration is low, they die of starvation. Therefore, since the BOD concentration of general domestic wastewater is about 100 mg / L, it has been found that the above method may not be used as it is.

  In addition, Patent Document 1 describes that the temperature of the bacterial treatment is increased from the viewpoint of preventing protozoa from being mixed during the bacterial treatment. Since the amount of heat becomes enormous, even if inexpensive heat such as waste heat of cogeneration is used, the heat cost may become larger than the cost merit due to sludge reduction.

  Furthermore, Patent Document 2 discloses that a solid food waste is finely crushed into a fluid bowl, and the obtained pulverized product is introduced into a high-temperature water tank together with raw water and solubilized with high-temperature hot water. Is described as biological treatment. When this inventor experimented according to patent document 2, it was confirmed that a part of bowl-shaped solid substance which flowed into the high-temperature water tank flows out into a biological treatment tank of a back | latter stage as it is. And the soot-like solids that flowed out to the biological treatment tank in the subsequent stage are almost untreated, and the form of waste such as vegetable waste remains, so it is difficult to treat in the biological treatment tank, resulting in the generation of sludge. It was confirmed that the amount may increase.

Moreover, in the treatment of organic wastewater, techniques including wastewater treatment with thermophilic bacteria at high temperatures are known (see, for example, Patent Documents 3 to 6). However, these techniques are techniques for decomposing solids after biological treatment at room temperature with thermophilic bacteria at high temperatures, and there remains room for study from the viewpoint of reducing the load in the biological treatment tank.
Japanese Patent Publication No. 56-48235 Japanese Patent No. 3643287 Japanese Patent No. 3267935 JP 2003-205279 A JP 2005-334886 A JP 2005-279464 A Issued by the Japan Sewerage Association, supervised by the Ministry of Construction City Bureau Sewerage Department, "Sewerage Facility Planning and Design Guidelines and Explanations", second part, 1994 edition

  The present invention provides a biological treatment technology for organic wastewater that can further reduce the amount of sludge generated.

  Moreover, this invention provides the biological treatment technique of the organic wastewater which can reduce more calorie | heat amount required for adjustment of the temperature of organic wastewater.

The present invention is a system for treating organic wastewater by a first solid-liquid separator, a high-temperature treatment tank, and a second solid-liquid separator. In the present invention, the organic waste water is separated into a solid phase and a liquid phase by a first solid-liquid separation device to obtain a supernatant and a liquid containing a large amount of solids, and only a liquid containing a large amount of solids is treated at a high temperature. The resulting treatment liquid is further separated into a solid phase and a liquid phase by the second solid-liquid separator, and the solid matter in the obtained solid phase is returned to the high-temperature treatment tank and the supernatant is obtained. Let said liquid phase, such as a liquid, be primary treated water. Then, the primary treated water is treated with a known biological treatment system to obtain purified treated water. When the organic wastewater has a high BOD, the primary treated water may not satisfy the release standard. However, the primary treated water may be obtained by a known biological treatment system such as a standard activated sludge method, a submerged membrane activated sludge method, or a contact aeration method. The treated water satisfying the discharge standard can be obtained.

  By separating the organic waste water with the first solid-liquid separator and increasing the ratio of solids in the inflow water to the high temperature treatment tank, the BOD concentration of the inflow water to the high temperature treatment tank increases. In a high-temperature treatment tank, solids are decomposed by thermophilic bacteria that inhabit at high temperatures. However, since these thermophilic bacteria are highly active, a lot of nutrients are always required. Therefore, thermophilic bacteria can be propagated in the high temperature treatment tank by increasing the BOD concentration of the inflow water to the high temperature treatment tank. Proliferation of thermophilic bacteria in the high-temperature treatment tank improves wastewater treatment capacity in the high-temperature treatment tank, and the amount of sludge generated can be reduced.

  Further, since only solid concentrated water having a high proportion of solids is allowed to flow into the high-temperature treatment tank, the amount of water in the high-temperature treatment tank can be reduced. Therefore, the amount of heat applied for temperature adjustment in the high-temperature treatment tank can be reduced, and the running cost can be reduced.

  In addition, a second solid-liquid separation device is provided downstream of the high-temperature treatment tank, and the solid matter obtained by the second solid-liquid separation device is returned to the high-temperature treatment tank, so that the solid matter that has not been subjected to high-temperature treatment can be discharged. And the residence time of the solid matter in the high-temperature treatment tank can be extended, and the solid matter flowing into the high-temperature treatment tank is sufficiently decomposed.

  As for the BOD concentration of the inflow water to the high-temperature treatment tank, thermophilic bacteria are sufficiently proliferated in this amount of nutrients in wastewater with a BOD concentration of about 100 mg / L, which is usually equivalent to wastewater generated at home. It has been confirmed that there may be no.

  More specifically, the present invention relates to a first solid-liquid separation device for solid-liquid separation of organic waste water containing an organic solid and water, and a solid-liquid in the first solid-liquid separation device. A high-temperature treatment tank for decomposing the solid in the first solid-containing liquid with thermophilic bacteria, to which a first solid-containing liquid containing solids by separation is supplied, and the high-temperature treatment tank A second solid-liquid separation device for solid-liquid separation of the thermophilic bacterium treatment liquid supplied with a thermophilic bacterium treatment liquid discharged from the liquid, and solid-liquid separation in the first solid-liquid separation device The first treated water as a liquid phase and the second treated water as a liquid phase by solid-liquid separation in the second solid-liquid separation device are supplied. A biological treatment tank for processing, and a second solid-containing liquid containing solids by solid-liquid separation in the second solid-liquid separation device is It is supplied to the high temperature treatment tank, to provide an organic waste water processing system.

  In the system, solids in organic wastewater are treated with thermophilic bacteria having relatively high decomposing activity, and the liquid phase in organic wastewater is treated with normal biological treatment with relatively low decomposing activity. Moreover, the solid substance in the liquid processed with the thermophilic bacterium is processed again with the thermophilic bacterium, and the liquid phase in the liquid processed with the thermophilic bacterium is processed with a normal biological treatment. Therefore, it is possible to further reduce the amount of sludge generated compared to a conventional system that first treats organic wastewater by ordinary biological treatment. In addition, in the treatment with thermophilic bacteria, it is necessary to heat the liquid to be treated. However, in the above system, only a part of the organic waste water can be used as the liquid to be treated. It is possible to further reduce the amount of heat necessary for adjusting the temperature as compared with the case of processing in step (1).

The present invention further includes a third solid-liquid separation device for solid-liquid separation of the biological treatment liquid supplied with the biological treatment liquid discharged from the biological treatment tank, and the third solid-liquid separation The third solid-containing liquid containing solids obtained by solid-liquid separation in the separation device may be supplied to one or both of the high-temperature treatment tank and the biological treatment tank. In this system, since the sludge generated by the biological treatment is treated again, it is possible to further reduce the amount of sludge generated. According to the viewpoint of reducing the amount of sludge generated, the third solid-containing liquid is supplied to both the biological treatment tank and the high-temperature treatment tank rather than the third solid-containing liquid is supplied only to the biological treatment tank. It is preferable to supply the third solid-containing liquid only to the high-temperature treatment tank.

  Moreover, in this invention, the said biological treatment tank is an activated sludge tank which has a tank supplied with said 1st and 2nd treated water, and an aeration pipe | tube for contacting the liquid and air in the said tank, The said tank, It is an immersion membrane activated sludge tank having the aeration tube and an immersion membrane for filtering the liquid in the tank, or a contact aeration tank having the tank, the aeration tube and a filler for containing the organism. Is preferable from the viewpoint of achieving both wastewater treatment capacity and economic merits.

  In the present invention, the high-temperature treatment tank is preferably a tank for treating the liquid in the tank at 40 to 95 ° C. from the viewpoint of developing sufficient processing capability for the solid-containing liquid.

  In addition, the present invention is excellent in wastewater treatment capacity and has a relatively low running cost such as a temperature control temperature. Therefore, organic wastewater containing organic solids derived from foods pulverized by a pulverizer It is preferably used for the treatment of organic waste water including disposer waste water.

  The system of the present invention includes the first and second solid-liquid separation devices, the high-temperature treatment tank, and the biological treatment tank, and the second solid-containing liquid is supplied to the high-temperature treatment tank. Therefore, organic wastewater can be sufficiently treated by living organisms, and the amount of generated sludge can be reduced. Furthermore, according to the system of the present invention, the amount of water flowing into the high-temperature treatment tank is small as compared with the total amount of waste water, so that a small amount of heat is sufficient.

  In the system of the present invention, when the third solid-liquid separator is further provided and the third solid-containing liquid is supplied to one or both of the high-temperature treatment tank and the biological treatment tank, the amount of sludge generated is reduced. It is further effective from the viewpoint of further reduction. Supplying the third solid-containing liquid only to the high-temperature treatment tank is more effective from the viewpoint of further reducing the amount of sludge generated. Supplying the third solid-containing liquid only to the biological treatment tank is even more effective from the viewpoint of suppressing an increase in cost for adjusting the temperature of the treatment liquid in the high-temperature treatment tank. Supplying the third solid-containing liquid to both the high-temperature treatment tank and the biological treatment tank achieves both a further reduction in the amount of sludge generated and a reduction in the cost for adjusting the temperature of the treatment liquid in the high-temperature treatment tank. From the viewpoint of making it more effective.

  In the system of the present invention, when the biological treatment tank is the activated sludge tank, the submerged membrane activated sludge tank, or the contact aeration tank, it is more effective from the viewpoint of obtaining a high treatment capacity in the treatment of organic wastewater at a relatively low cost. Is.

  In the system of the present invention, it is more effective from the viewpoint of sufficiently reducing the amount of sludge generated that the high-temperature treatment tank is a tank for treating the liquid in the tank at 40 to 95 ° C.

  The system of the present invention is more effective in the treatment of organic wastewater containing organic solids derived from foodstuffs crushed by a crusher, and is more effective in the treatment of organic wastewater including disposer wastewater. It is.

The organic wastewater treatment system of the present invention includes a first solid-liquid separation device for solid-liquid separation of organic wastewater containing organic solids and water, and the first solid-liquid separation device. A high-temperature treatment tank for decomposing the solid in the first solid-containing liquid with thermophilic bacteria, to which a first solid-containing liquid containing solids by solid-liquid separation is supplied, and the high temperature A second solid-liquid separation device for solid-liquid separation of the thermophilic bacterium treatment liquid, which is supplied with a thermophilic bacterium treatment liquid that is a liquid discharged from the treatment tank;
First treated water that is a liquid phase by solid-liquid separation in the first solid-liquid separation device and second treated water that is a liquid phase by solid-liquid separation in the second solid-liquid separation device are supplied. A biological treatment tank for treating the first and second treated water with a living organism.

  As the first and second solid-liquid separators, there can be used ordinary solid-liquid separators used for separating organic solids and sludge generated during processing from the liquid phase. Examples of such a solid-liquid separation device include known solid-liquid separation devices such as a sedimentation tank, a pressure levitation device, a screen and a net. The first and second solid-liquid separation devices may be the same type of device, or may be different types of devices.

  The said high temperature processing tank will not be specifically limited if it is a tank which can maintain the temperature of the liquid in a tank to the temperature which a thermophile can decompose | disassemble a solid substance etc. The high-temperature treatment tank is preferably a tank for treating the liquid in the tank at 40 to 95 ° C., from the viewpoint of sufficiently expressing the ability to decompose solids by thermophilic bacteria. It is more preferable that it is a tank for processing at 70 degreeC. As the high-temperature treatment tank, a known tank used in wastewater treatment by thermophilic bacteria can be used, and for example, it can be constituted by a tank and a heating device for adjusting the liquid temperature in the tank. In the case where an aerobic thermophilic bacterium is used as the thermophilic bacterium, the high-temperature treatment tank further has an aeration tube.

  The biological treatment tank may be a known tank used for treating organic wastewater at room temperature. As such a biological treatment tank, for example, an activated sludge tank having a tank to which the first and second treated waters are supplied and an air diffuser for bringing the liquid and air in the tank into contact with each other, the tank A submerged membrane activated sludge tank having an immersion film for filtering the liquid in the tank and the aeration pipe, and a contact aeration tank having a filling material for containing the tank, the aeration pipe and the organism, Etc.

  In particular, the immersed membrane activated sludge tank and the contact aeration tank can retain activated sludge in the tank for a longer time than the activated sludge tank, which is excellent in terms of reducing the amount of sludge generated. ing. Furthermore, the submerged membrane activated sludge tank is excellent in terms of further reducing the suspended solids concentration (SS) of the treated water because the liquid filtered in the tank is obtained as the treated water.

  In the system of the present invention, a second solid-containing liquid containing solids obtained by solid-liquid separation in the second solid-liquid separator is supplied to the high-temperature treatment tank.

  In the present invention, the supply of the solid-containing liquid from the solid-liquid separator to the processing tank can be performed with an appropriate configuration according to the form of the solid-liquid separator. For example, in the case where the solid-liquid separation device is a precipitation tank, a pipe connecting the bottom of the precipitation tank where the solid is precipitated and the treatment tank, a valve for opening and closing the pipe, and a liquid in the pipe The solid-containing liquid can be supplied from the solid-liquid separator to the processing tank by a pump for feeding the liquid to the processing tank.

  For example, in the case where the solid-liquid separation device is a device that separates a solid and a liquid phase using a filtration member such as a screen or a net, the filtration member that collects the solid is used as an organic wastewater or the liquid phase ( An apparatus for cleaning with treated water), a pipe connecting the apparatus and the treatment tank, a valve for opening and closing the pipe, and a washing liquid generated in the washing apparatus and supplied to the pipe toward the treatment tank The solid-containing liquid can be supplied from the solid-liquid separator to the treatment tank by a pump for feeding.

  In addition, the supply of the solid-containing liquid from the solid-liquid separator to the treatment tank and the supply of the organic waste water to the first solid-liquid separator are performed by detecting the flow rate with a flow meter, operating the pump, and opening the valve. It is possible to adjust continuously or intermittently using a normal technique such as degree.

  The organic waste water contains an organic solid and water. The organic solid is not particularly limited, and examples of the organic solid include organic solids derived from foods (so-called garbage) pulverized by a pulverizer. Examples of the organic waste water containing, include a disposer drainage discharged from a disposer that is a pulverizer. Disposer waste water may be used as it is as organic waste water, or may be used after appropriately diluted with other waste water or water.

  The thermophilic bacterium is not particularly limited as long as it is a bacterium that decomposes organic solids at a high temperature (for example, 40 to 95 ° C.) in a high-temperature treatment tank. The thermophilic bacterium may be an aerobic bacterium or an anaerobic bacterium. As thermophiles, for example, as described in JP-A-2003-205279, thermophiles such as Bacillus stearothermophilus itself, and commercially available microbial preparations containing such thermophiles Is mentioned. The thermophilic bacterium can be obtained from the bacterium or the microbial preparation, but is obtained by culturing the bacterium in the organic waste water at the treatment temperature in the high temperature treatment tank, and is grown at the treatment temperature. Can also be used as the thermophilic bacterium.

  As the organism used for the treatment in the biological treatment tank, an organism used in a normal biological treatment method of sewage such as a standard activated sludge method, a submerged membrane activated sludge method, or a contact aeration method can be used. Examples of such organisms include bacteria such as Acinetobacter bacteria, Alkagenes bacteria, Pseudomonas bacteria, Bacillus bacteria, Aerobacter bacteria, Flavobacterium bacteria, and the like as described in Japanese Patent No. 3643287. And protozoa such as stalk-fixed ciliates such as vorticella, epistairis, opelclaria, calcesium, and zutanium, commercially available preparations containing the bacteria and the protozoa, and activities containing the bacteria and the protozoa Examples include sludge.

  The system of the present invention may further include a third solid-liquid separation device for solid-liquid separation of the biological treatment liquid supplied with a biological treatment liquid that is a liquid discharged from the biological treatment tank. good. As the third solid-liquid separation device, the same device as the first and second solid-liquid separation devices described above can be used.

  The third solid-containing liquid containing solids obtained by solid-liquid separation in the third solid-liquid separator is supplied to one or both of the high-temperature treatment tank and the biological treatment tank. The supply of the third solid-containing liquid to the high-temperature treatment tank and the biological treatment tank can be performed in the same manner as the above-described supply of the second solid-containing liquid to the high-temperature treatment tank.

  The system of the present invention may further include other components other than the above-described apparatus. Examples of such other constituent elements include an ozone generator for treating sludge in treated water. According to the ozone generator, sludge can be solubilized or sterilized. In particular, when the ozone generator is used for treated water, it is possible to decompose hardly decomposed substances in the treated water such as humic substances and to remove chromaticity accordingly.

  In addition, the system of the present invention includes, as the other component, a device for adjusting the pH in the tank, and a nutrient as a device for adjusting a thermophilic bacterium in a high-temperature treatment tank and a living environment in a biological treatment tank. You may have further the apparatus etc. which replenish.

  The system of the present invention is configured as shown in FIG. 1, for example. The system of FIG. 1 includes a first settling tank 1 to which organic waste water is supplied, a high-temperature treatment tank 2 connected to the bottom of the first settling tank 1, and a second liquid to which the liquid in the high-temperature treatment tank 2 is supplied. A sedimentation tank 3, a biological treatment tank 4 connected to each of the upper part of the first precipitation tank 1 and the upper part of the second precipitation tank 3, and a third precipitation tank 5 to which the liquid of the biological treatment tank 4 is supplied Have. The bottom of the second sedimentation tank 3 and the high temperature treatment tank 2 are connected, and the bottom of the third sedimentation tank 5 and the biological treatment tank 4 are connected.

  The first settling tank 1 is supplied with organic waste water such as a disposer drain or a diluted solution thereof. Solids in the organic wastewater are precipitated at the bottom of the first precipitation tank 1, and the liquid in the first precipitation tank 1 is divided into a precipitate and a supernatant.

  The sediment in the first sedimentation tank 1 is extracted from the bottom of the first sedimentation tank 1 together with the liquid in the first sedimentation tank 1. The liquid extracted from the bottom of the first sedimentation tank 1 contains a large amount of sediment in the first sedimentation tank 1, and this liquid (first solid-containing liquid) is supplied to the high-temperature treatment tank 2. The The amount of liquid extracted from the bottom of the first sedimentation tank 1 may be of a level that does not increase the deposit height of the sediment in the first sedimentation tank 1, for example, the concentration of solids in the organic wastewater is 500 to 500. If it is 2,000 mg / L, it will be 10 to 40% of the inflow amount of the organic waste water to the first sedimentation tank 1. However, the amount of liquid extracted from the bottom of the first sedimentation tank 1 depends on the sedimentation property of the solid matter in the inflowing organic waste water, and is low when the sedimentation property is good, and increases when the sedimentation property is poor. It may be out of the range.

  The high-temperature treatment tank 2 has, for example, a jacket for adjusting the liquid temperature in the tank and a diffuser tube for gas-liquid contact in the tank, and is loaded with aerobic thermophilic bacteria. The liquid extracted from the bottom of the first sedimentation tank 1 is processed by thermophilic bacteria in the high-temperature processing tank 2, and the solid matter in the liquid is decomposed by thermophilic bacteria.

  The liquid (thermophilic treatment liquid) treated in the high temperature treatment tank 2 is supplied to the second precipitation tank 3. The solid of the thermophilic bacterium treatment liquid is precipitated at the bottom of the second precipitation tank 3, and the liquid in the second precipitation tank 3 is divided into a precipitate and a supernatant. The sediment in the second sedimentation tank 3 is extracted from the bottom of the second sedimentation tank 3 together with the liquid in the second sedimentation tank 3. The liquid extracted from the bottom of the second sedimentation tank 3 contains a large amount of sediment in the second sedimentation tank 3, and this liquid (second solid-containing liquid) is supplied to the high-temperature treatment tank 2. The The amount of liquid withdrawn from the bottom of the second sedimentation tank 3 may be such that it does not increase the deposit height of the sediment in the second sedimentation tank 3. For example, the concentration of solids in the thermophilic bacteria treatment liquid is If it is 250 to 1,000 mg / L, it is 5 to 20% of the inflow amount of the thermophilic bacteria treatment liquid to the second sedimentation tank 3. However, the extraction amount of the liquid from the bottom of the second sedimentation tank 3 depends on the sedimentation property of the solid matter in the inflowing thermophilic treatment solution, and is small when the sedimentation property is good and increases when the sedimentation property is poor. Therefore, it may be out of the range.

  On the other hand, the supernatant liquid of the first sedimentation tank 1 is supplied to the biological treatment tank 4. The supernatant liquid of the second sedimentation tank 3 is also supplied to the biological treatment tank 4. The biological treatment tank 4 is an activated sludge tank having, for example, a tank and an air diffuser for bringing the liquid and air in the tank into contact with each other, and contains activated sludge. The supernatant liquid is treated in the biological treatment tank 4 by the organisms in the activated sludge, and the organic matter in the supernatant liquid is decomposed by the organisms in the activated sludge.

  The liquid (biological treatment liquid) processed in the biological treatment tank 4 is supplied to the third precipitation tank 5. Solid matter of the biological treatment liquid is precipitated at the bottom of the third settling tank 5, and the liquid in the third settling tank 5 is divided into a precipitate and a supernatant. The precipitate in the third settling tank 5 is extracted from the bottom of the third settling tank 5 together with the liquid in the third settling tank 5. The liquid extracted from the bottom of the third sedimentation tank 5 contains a large amount of sediment in the third sedimentation tank 5, and this liquid (third solid-containing liquid) is supplied to the biological treatment tank 4. The The extraction amount of the liquid from the bottom of the third sedimentation tank 5 is set to be equal to the activated sludge treatment that is generally performed.

  The supernatant liquid of the third sedimentation tank 5 is discharged into sewage as final treated water.

In the system of FIG. 1, the solid matter in the organic waste water is selectively supplied to the high temperature treatment tank 2, and the solid matter is decomposed in the high temperature treatment tank 2. Thus, the solid matter in the organic wastewater having a high treatment load can be selectively supplied to the high-temperature treatment tank 2 having a high treatment capacity and decomposed.

  Further, in the system of FIG. 1, the sediment in the second sedimentation tank 3 is selectively returned to the high temperature treatment tank 2. Therefore, since the sludge produced by the treatment of the solid matter is further decomposed in the high-temperature treatment tank 2, the amount of sludge generated due to the treatment of the solid matter can be reduced.

  In the system of FIG. 1, the sediment in the second sedimentation tank 3 is selectively returned to the high temperature treatment tank 2, so that untreated solid matter can be returned to the high temperature treatment tank 2, and the solid in the high temperature treatment tank 2 The residence time of the product can be increased. Therefore, the solid material can be sufficiently processed.

  In the system of FIG. 1, a part of the organic waste water and a part of the thermophilic bacterium treatment liquid are supplied to the high temperature treatment tank 2. Thus, the amount of the liquid whose temperature should be adjusted in the high temperature treatment tank 2 can be reduced, and the cost for adjusting the temperature of the liquid in the high temperature treatment tank 2 can be reduced.

  Further, in the system of FIG. 1, the supernatant liquid of the first precipitation tank 1 and the supernatant liquid of the second precipitation tank 3 having a relatively low processing load are supplied to the biological treatment tank 4. Therefore, treated water satisfying the discharge standard can be obtained by biological treatment in the biological treatment tank 4.

  Moreover, in the system of FIG. 1, since the sediment of the 3rd sedimentation tank 5 is returned to the biological treatment tank 4, from the viewpoint of preventing sludge reduction in the biological treatment tank 4 and outflow of sludge to the final treated water. Even more effective.

  The system of the present invention is configured as shown in FIG. 2, for example. The system of FIG. 2 is the same as the system of FIG. 1 except that the bottom of the third sedimentation tank 5 is connected to both the high temperature treatment tank 2 and the biological treatment tank 4.

  In the system of FIG. 2, the sediment in the third sedimentation tank 5 is supplied to both the biological treatment tank 4 and the high temperature treatment tank 2 at an appropriate ratio. Therefore, the solid time such as sludge generated in the biological treatment tank 4 can be extended in the biological treatment tank 4 or decomposed in the high-temperature treatment tank 2. The distribution of the third solid-containing liquid from the third sedimentation tank 5 to the high-temperature treatment tank 2 and the biological treatment tank 4 in the system of FIG. 2 is performed, for example, according to the increase in SS of the biological treatment liquid. It can adjust suitably according to water quality, such as SS of the biological treatment liquid which flows into the 3rd sedimentation tank 5, such as increasing the supply amount of a 3rd solid substance containing liquid.

  The system in FIG. 2 is more effective than the system in FIG. 1 from the viewpoint of reducing the amount of sludge generated and improving the quality of the final treated water.

  Furthermore, the system of the present invention is configured as shown in FIG. 3, for example. In the system of FIG. 3, the biological treatment tank 4 is an immersion membrane activated sludge tank having, for example, a tank, the air diffuser, and an immersion membrane for filtering the liquid in the tank, and has a third sedimentation tank 5. The third solid-containing liquid is the same as the system in FIG. 1 except that the biological treatment tank 4 is not supplied.

  In the system of FIG. 3, the final treated water filtered through the immersion membrane is obtained. Therefore, it is more effective from the viewpoint of improving the quality of the final treated water.

  The system of the present invention can be widely used for wastewater treatment in houses, apartment houses, restaurants, food manufacturing factories, and the like, and exhibits excellent effects of the present invention in these applications.

[Example 1]
Using the organic wastewater treatment system shown in FIG. 1, the test wastewater which is organic wastewater was treated. The capacity, material and form of each tank in the organic wastewater treatment system of FIG. 1 are as follows.
First to third settling tanks: 10 L (made of PVC, conical)
High temperature treatment tank: 10L (made of stainless steel, jacket type for heating)
Biological treatment tank: 20L (PVC, square type)

  The composition of the test wastewater, the inflow time, and the ratio of the inflow amount were in accordance with “Disposer wastewater treatment system performance standards for sewage (draft)” (Japan Sewage Association, March 2004). For the test wastewater, disposer drainage prepared based on the description of “[3] Disposer drainage conditions” in the above-mentioned document is used, and the water quality tolerance of “raw water for test” described in “Document 8 Test Method” in the above-mentioned document is used. A solution diluted with water so as to be in the range was used. The garbage to be crushed by the disposer was prepared in accordance with the descriptions in “Document 3 Composition of Standard Garbage” and “Document 4 Preparation Method of Standard Garbage”.

  The inflow time and the inflow amount of the test wastewater were based on the description in “Document 8 Test Method” in the above literature. In addition, the amount of inflow of test wastewater was 0.5 people. That is, based on the description of the “raw water inflow pattern example” in the above document, the following table was used.

  Air was supplied to the high-temperature treatment tank and the biological treatment tank through an air diffuser. Air was supplied to the high temperature treatment tank at 10 L / min, and air was supplied to the biological treatment tank at 5 L / min. Moreover, the liquid temperature of the high temperature treatment tank was kept at 65 ° C., and the liquid temperature of the biological treatment tank was kept at room temperature (about 23 ° C.). For the thermophilic bacteria in the high temperature treatment tank, the bacteria in the organic wastewater that grows in the environment in the high temperature treatment tank was used. That is, the test wastewater was introduced into the present system or a system having the same configuration under the above-described conditions, and the bacteria that grew in a high-temperature treatment tank in which the temperature of the liquid in the tank was 65 ° C. were used for 1 to 2 weeks. The growth of thermophilic bacteria was confirmed by visually observing that the appearance (color) of the liquid in the high-temperature treatment tank changes (darkens). Moreover, the activated sludge used by the treatment of another organic wastewater was used for the treatment organism in a biological treatment tank.

  The inflow amount of the first solid-containing liquid from the first precipitation tank to the high-temperature treatment tank was adjusted so that all the precipitates in the first precipitation tank flowed to the high-temperature treatment tank. The inflow amount of the first solid-containing liquid from the first precipitation tank to the high-temperature treatment tank was about 20% of the total amount of water in the high-temperature treatment tank.

  The inflow amount of the second solid-containing liquid from the second precipitation tank to the high-temperature treatment tank was adjusted so that the solids did not accumulate in the second precipitation tank. The inflow of the second solid-containing liquid from the second precipitation tank to the high-temperature treatment tank was about 30% of the total inflow of the solid-containing liquid into the high-temperature treatment tank.

The inflow amount of the third solid content from the third settling tank to the biological treatment tank was adjusted to be about 50% of the total inflow amount of the treatment liquid and the solid content liquid into the biological treatment tank.

  The test wastewater was treated for 30 days under the conditions described above. Then, when the deposits in the high-temperature treatment tank and the second sedimentation tank were examined, there was almost no precipitate except for the eggshell that was not biologically treated. Moreover, when the biological treatment tank and the third sedimentation tank were investigated, solids such as vegetable waste were not confirmed. Table 1 shows the quality of raw water (test wastewater) and the final treated water that is the supernatant of the third sedimentation tank. It was found that by using this system, the drainage standard values (SS: 300 mg / L or less, BOD: 300 mg / L or less) were sufficiently satisfied. SS and BOD are the methods described in “Document 5 Disposer Wastewater Disposal Wastewater Treatment System Performance Standard (Draft)” described in “Document 5 Method for Measuring Discharged Wastewater Full Load Water Quality” and issued by Japan Sewerage Association. It was obtained in accordance with the "Sewage Test Method"-1997 edition, supervised by the Ministry of Construction, Urban Bureau, Sewerage Department, Ministry of Health and Welfare, Health Sanitation Bureau, Water Environment Department.

[Comparative Example 1]
The test wastewater was treated in the same manner as in Example 1 except that the temperature of the liquid in the high-temperature treatment tank was kept at room temperature (about 23 ° C.). Table 2 shows the quality of raw water and final treated water. In Comparative Example 1, since it was overloaded, the sludge was bulked, the final treated water could not be obtained, the test wastewater could not be treated continuously for 30 days, and the treatment of the test wastewater was stopped halfway. The experimental results in Table 2 are values when final treated water is still obtained. When the deposits in the high temperature treatment tank and the second sedimentation tank were examined, it was confirmed that in Comparative Example 1, about half of the tank was filled with untreated garbage, and the test wastewater could not be treated at room temperature.

[Comparative Example 2]
The test wastewater was treated in the same manner as in Example 1 except that the lower sedimentation tank, that is, the second sedimentation tank, was removed. Table 2 shows the quality of raw water and final treated water. In Comparative Example 2, by not providing a sedimentation tank after the high-temperature treatment tank, the quality of the final treated water by the solid matter contained in the first solid-containing liquid flowing into the high-temperature treatment tank flows out to the biological treatment tank as it is. Deterioration was seen.

  Furthermore, Table 3 shows the amount of relative excess sludge generated in Example 1 and Comparative Examples 1 and 2. The amount of excess sludge generated was determined by measuring the total amount of SS in the test system before the start of the test and after the completion of the test, and obtaining the difference.

The amount of surplus sludge generated was smaller in Example 1 than in Comparative Examples 1 and 2. In addition, although it cannot express by a numerical value, the activated sludge in a biological treatment tank is the sludge in Example 1, and the stable operation | movement was possible during the process of test wastewater. In Comparative Example 2, it was confirmed that garbage was mixed in the activated sludge in the biological treatment tank, and the amount thereof increased as the treatment of the test wastewater proceeded. From this, it was confirmed that the garbage in the test wastewater was not completely treated.

[Example 2]
As shown in FIG. 2, the test wastewater was treated in the same manner as in Example 1 except that a part of the third solid-containing liquid in the third sedimentation tank was returned to the high-temperature treatment tank. Specifically, about 10% of the third solid-containing liquid was returned to the high temperature treatment tank. As a result, the amount of excess sludge was reduced by about 20% compared to Example 1. Table 4 shows the amount of excess sludge generated relative to Example 1. In addition, the quality of the final treated water at this time was the same as in Example 1. The decrease in excess sludge in this example is considered to be a result of predation of sludge by thermophilic bacteria, but details are unknown.

[Example 3]
As shown in FIG. 3, the test wastewater was treated in the same manner as in Example 1 except that a submerged membrane activated sludge tank was provided instead of the biological treatment tank and the third sedimentation tank was removed. Table 5 shows the quality of raw water and final treated water. Table 6 shows the amount of excess sludge generated relative to Example 1.

  By using an immersion film, very good final treated water can be obtained. In addition, the amount of excess sludge generated was smaller than that in Example 1. In addition, when the immersion membrane was used, the quality of the final treated water was good, and SS was accumulated in the immersion membrane activated sludge tank. Therefore, the amount of surplus sludge generated was larger than that in Example 2. The reason why the amount of surplus sludge generated is smaller than that in Example 1 is considered to be that the sludge self-digestion occurred because the sludge residence time in the submerged membrane activated sludge tank is long.

It is a figure which shows roughly the structure of an example of the organic wastewater treatment system of this invention. It is a figure which shows roughly the structure of the other example of the organic wastewater treatment system of this invention. It is a figure which shows roughly the structure of the other example of the organic wastewater treatment system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st precipitation tank 2 High temperature treatment tank 3 2nd precipitation tank 4 Biological treatment tank 5 3rd precipitation tank

Claims (7)

A first solid-liquid separation device for solid-liquid separation of organic wastewater containing organic solids and water;
The first solid-containing liquid containing the solid by solid-liquid separation in the first solid-liquid separator is supplied, and the solid in the first solid-containing liquid is decomposed by thermophilic bacteria. A high-temperature treatment tank,
A second solid-liquid separation device for solid-liquid separation of the thermophilic bacterium treatment liquid supplied with a thermophilic bacterium treatment liquid discharged from the high-temperature treatment tank;
First treated water that is a liquid phase by solid-liquid separation in the first solid-liquid separation device and second treated water that is a liquid phase by solid-liquid separation in the second solid-liquid separation device are supplied. A biological treatment tank for treating the first and second treated water with a living organism,
An organic wastewater treatment system in which a second solid-containing liquid containing solids obtained by solid-liquid separation in the second solid-liquid separator is supplied to the high-temperature treatment tank. A third solid-liquid separation device for solid-liquid separation of the biological treatment liquid supplied with the biological treatment liquid discharged from the biological treatment tank;
The third solid-containing liquid containing solids obtained by solid-liquid separation in the third solid-liquid separator is supplied to one or both of the high-temperature treatment tank and the biological treatment tank. The organic wastewater treatment system according to claim 1.   The organic wastewater treatment system according to claim 2, wherein the third solid-containing liquid is supplied to each of the biological treatment tank and the high-temperature treatment tank.   The biological treatment tank has an activated sludge tank having a tank to which the first and second treated waters are supplied and an air diffuser for contacting the liquid and air in the tank, the tank, the air diffuser, and the air It is a submerged membrane activated sludge tank having a submerged membrane for filtering the liquid in the tank, or a contact aeration tank having the tank, the air diffuser, and a filler for containing the organism. The organic wastewater treatment system according to claim 1.   The organic wastewater treatment system according to any one of claims 1 to 4, wherein the high-temperature treatment tank is a tank for treating a liquid in the tank at 40 to 95 ° C.   The organic wastewater treatment according to any one of claims 1 to 5, wherein the solid matter in the organic wastewater is a food-derived organic solid matter pulverized by a pulverizer. system.   The organic wastewater treatment system according to claim 6, wherein the pulverizer is a disposer, and the organic wastewater includes disposer drainage discharged from the disposer.

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