JP2012005971A - Organic wastewater treatment system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic wastewater treatment system high in purification treatment capability.SOLUTION: The wastewater treatment system A for purifying organic wastewater by using microorganisms circulates the organic wastewater in a substantially-sealed anaerobic circulation water passage 21, and comprises an anaerobic treatment unit 2 which ferments methane. The wastewater treatment system also comprises an aerobic treatment unit 3 which circulates anaerobic treatment water in an aerobic circulation water passage 31 while aerating it, and makes aerobic microorganisms decompose organic substances. By fermenting the methane in the circulation water passage, operation cost and construction cost can be reduced. Furthermore, by continuously performing anaerobic treatment (fixed-floor methane fermentation treatment) and aerobic treatment (treatment by a fixed-floor oxidation ditch method), the purification treatment capacity with respect to the organic wastewater can largely be improved.

Description

  The present invention relates to an organic wastewater treatment system for performing methane fermentation in a substantially sealed anaerobic circulation channel, an organic wastewater treatment system for performing an aerobic treatment by an oxidation ditch method as a subsequent treatment of the anaerobic treatment, Or it is related with the organic wastewater treatment system which installed the fixed bed (for example, nonwoven fabric etc.) which can fix aerobic microorganisms, the organic wastewater treatment method similar to them, etc.

  When wastewater with high organic matter content, such as domestic wastewater and industrial wastewater, flows into rivers, etc., exceeding the self-cleaning action of nature, water pollution progresses. When organic wastewater flows into rivers, aerobic microorganisms temporarily grow and dissolved oxygen decreases. This in turn activates anaerobic microorganisms, causing bad odors and adverse effects on aquatic organisms, leading to deterioration of living and natural environments. Therefore, in order to prevent water pollution, it is preferable to perform an appropriate purification treatment of organic waste water before releasing it into a river or the like.

  As a means for purifying organic wastewater, the activated sludge method, the methane fermentation method, etc. are widely adopted.

  The activated sludge method is a wastewater treatment method in which sludge containing aerobic microorganisms (activated sludge) and organic wastewater are mixed and stirred while aerated to oxidatively decompose organic matter.

  When activated sludge and organic wastewater are mixed and stirred in an appropriate ratio in the presence of oxygen, aerobic microorganisms in the activated sludge grow using organic matter, and floating particles such as microorganisms, organic matter, and inorganic matter Flocculate to form flocs. Since good flocs are excellent in cohesiveness and sedimentation, clean water can be obtained by removing sludge from the water after aeration by sedimentation separation / filtration.

  In addition to the standard activated sludge method, the activated sludge method includes a long-time aeration method (long-time aeration method), oxidation ditch method (oxidation groove method), two-stage aeration method, anaerobic aerobic method (AO method) membrane separation Many modified methods have been developed and put into practical use, including the activated sludge method.

  Among them, the oxidation ditch method is a wastewater treatment method in which activated sludge and organic wastewater are mixed and stirred to circulate wastewater while aerated in a circulating waterway (endless waterway) to decompose organic matter. Operation management is simple, stable removal of organic matter can be performed even if there is a temporal change in the amount and quality of the influent wastewater, the amount of sludge generated can be reduced, and the amount of aeration can be reduced. It has the advantage of being able to control costs and is often used in relatively small wastewater treatment facilities.

  On the other hand, the methane fermentation method is a method of generating methane by decomposing organic wastewater, organic waste, etc. by anaerobic microorganisms. Organic matter is decomposed into methane, carbon dioxide, water, etc. by methane fermentation. Methane can also be used as an energy source. Since methane fermentation is performed under anaerobic conditions, it does not require aeration power and is an energy-saving processing method. In addition, wastewater with a high organic matter content can be decomposed and purified by methane fermentation.

  In addition to the fermentation at normal temperature, the methane fermentation method includes a medium temperature fermentation method in which fermentation is performed at around 37 ° C. and a high temperature fermentation method in which fermentation is performed at around 55 ° C. Among them, the high-temperature fermentation method has a large energy loss for heating, but has advantages such as high decomposition efficiency of organic substances, a small fermentation tank, and high-temperature sterilization treatment.

Patent Document 1 describes an anaerobic treatment method and apparatus for an organic substance-containing liquid using methanogens and other anaerobic microorganisms. In addition, regarding the oxidation ditch method, for example, in Patent Document 2, a flow rate adjusting tank is provided in the front stage of the aeration tank, the sludge precipitated in the settling tank is returned to the flow rate adjusting tank, and mixed with the inflowing sewage to remove the sludge. The denitrification / dephosphorization method in the oxidation ditch that is allowed to flow into the aeration tank after the complete anaerobic state is disclosed in Patent Document 3, the nitrogen removal method and apparatus in the membrane separation type oxidation ditch, and in Patent Document 4, An oxidation ditch method and apparatus having an aerobic zone and an anaerobic zone are described in Patent Document 5, and a control method and a control apparatus for an oxidation ditch type water treatment apparatus are described.
Japanese Patent No. 4368171 JP-A-7-290083 JP 2003-1293 A JP 2003-285095 A JP-A-8-323384

  An object of the present invention is to provide a wastewater treatment means having a high purification capacity.

  In the present invention, first, an organic wastewater treatment system for purifying organic wastewater using microorganisms, anaerobic treatment for circulating organic wastewater in a substantially sealed anaerobic circulation channel and methane fermentation Provided are an organic wastewater treatment system provided with a means, and an organic wastewater treatment method similar to that.

  By performing anaerobic treatment (methane fermentation) in the circulation channel, the reaction tank can be mixed and stirred with less power consumption, so that the opportunity for contact between the degradation substrate and the methane fermentation microorganism group is maintained while reducing the operating cost. It is possible to maintain the wastewater treatment capacity almost equivalent to that of a conventional methane fermentation treatment facility. In addition, since construction costs such as digestion tanks can be omitted, it is possible to reduce the cost of constructing a wastewater treatment facility. In addition, for example, by installing a fixed bed to which methane fermentation microorganisms can be established in an anaerobic circulation channel, the anaerobic treatment capacity can be greatly improved, and the wastewater treatment speed can be increased or the wastewater treatment facility can be downsized. Can be realized.

  In the present invention, secondly, as the latter stage treatment of the anaerobic treatment, the anaerobic treatment means is provided with an aerobic treatment means for circulating the anaerobic treatment water in the aerobic circulation channel while aeration, and decomposing the organic matter into the aerobic microorganisms. A wastewater treatment system and an organic wastewater treatment method similar to the wastewater treatment system are provided.

  By performing the purification process by the oxidation ditch method as a subsequent process of the anaerobic process, the purification capacity can be greatly improved. Therefore, even when wastewater with a high organic matter content or wastewater with a large fluctuation in the organic matter content flows in, the purification treatment can be appropriately performed. In addition, by installing a fixed bed in which aerobic microorganisms can be fixed in the aerobic circulation channel, the purification treatment capacity can be further greatly improved.

  As described above, methane fermentation is performed in the circulation channel, and anaerobic treatment (methane fermentation treatment) and aerobic treatment (treatment by the oxidation ditch method) are performed continuously to purify organic wastewater. The capacity can be greatly improved, enabling large-scale wastewater treatment. Moreover, compared with the conventional wastewater treatment means, the wastewater treatment facility itself can be greatly downsized while maintaining the same treatment capacity.

  In addition, by making both the anaerobic treatment means and the aerobic treatment means into circulation channels and approximating the shape and water circulation means of both, there is an advantage that the construction cost and operation cost of this wastewater treatment system can be reduced.

  According to the present invention, it is possible to improve the purification treatment capacity for organic wastewater.

<About the organic wastewater treatment system according to the present invention>
Hereinafter, an example of the organic wastewater treatment system according to the present invention will be described with reference to FIGS. 1 and 2. The present invention includes all organic wastewater treatment systems having at least a configuration including anaerobic treatment means for circulating organic wastewater in a substantially sealed anaerobic circulation channel and performing methane fermentation. The present invention is not limited to the embodiments.

  FIG. 1 is a schematic diagram showing an example of an organic wastewater treatment system according to the present invention.

  An organic wastewater treatment system A shown in FIG. 1 includes a storage tank 1 that stores organic wastewater, anaerobic treatment means 2 that circulates organic wastewater in a substantially sealed anaerobic circulation channel 21 and performs methane fermentation. And aerobic treatment means 3 that circulates organic wastewater in the aerobic circulation channel 31 while aeration, and decomposes organic matter into aerobic microorganisms.

  In the organic wastewater treatment system A shown in FIG. 1, the organic wastewater is first supplied to the anaerobic treatment means 2 (see symbol X1) and circulates in the circulation channel 21 (see symbol X2). In that case, an anaerobic process is performed as a front | former stage process, and organic substance is decomposed | disassembled by methane fermentation. Biogas generated by methane fermentation is recovered (see symbol Y1) and can be used as an energy resource.

  Next, the primary treated water treated by the anaerobic treatment means 2 is sent to the aerobic treatment means 3 (see symbol X3) and circulates in the circulation channel 31 (see symbol X4). At that time, an aerobic treatment is performed to decompose the organic matter. Through the above process, treated water that has been purified is obtained (see symbol X5).

  The storage tank 1 is a part for storing organic wastewater before wastewater treatment, and can be appropriately provided as necessary. For example, an organic wastewater treatment system is configured to supply organic wastewater to the anaerobic treatment means 2 while adjusting the supply amount using a known liquid supply means (not shown) such as a pump. Operation A may be performed.

  The organic wastewater may be any wastewater containing organic matter, for example, domestic wastewater (including wastewater generated from kitchens, bathhouses, washing, cleaning, etc.) and industrial wastewater (food factories, biofuel manufacturing factories).・ Including plant wastewater generated at other factories, livestock wastewater such as human waste, etc.), water mixture of various pollutants and other organic waste, and sewage mixed with rainwater .

  The anaerobic treatment means 2 includes a substantially sealed circulation channel (endless channel) 21. The organic wastewater is circulated in the water channel 21 and subjected to methane fermentation under anaerobic conditions to decompose organic matter and recover the generated biogas as an energy resource.

  As described above, by performing methane fermentation in the circulation channel, the reaction tank can be mixed and stirred with power saving, so the opportunity to contact the decomposition substrate and the methane fermentation microorganism group can be maintained while reducing the operating cost. It is possible to maintain the wastewater treatment capacity almost equivalent to that of the conventional methane fermentation treatment facility. In addition, since construction costs such as digestion tanks can be omitted, it is possible to reduce the cost of constructing a wastewater treatment facility.

  The anaerobic treatment means 2 only needs to form a circulation channel, and the shape, material, size, depth, etc. thereof are not particularly limited. For example, the predetermined groove may be formed of reinforced concrete. The construction cost and operation cost can be reduced by approximating the shape of the anaerobic treatment means 2 and the shape of the aerobic treatment means 3 described later, the water circulation means, and the like.

  Since the anaerobic treatment means 2 performs anaerobic treatment, it needs to have a substantially sealed structure. A known method can be used for the means for providing a substantially sealed structure, and is not particularly limited.

  In general, methane fermentation proceeds at room temperature, but from the viewpoint of increasing the reaction efficiency of methane fermentation, the temperature of the circulating water is set to medium temperature (around 37 ° C., for example, 30 to 40 ° C.) or high temperature (around 55 ° C., for example, You may make it the structure provided with the mechanism adjusted to 50-70 degreeC.

  Thereby, the decomposition | disassembly efficiency (purification capability of organic wastewater) of organic substance can be made high, and the circulating water channel 21 can be reduced in size. In addition, for example, performing methane fermentation treatment at high temperature has an advantage that high-temperature sterilization treatment is performed. In addition, when performing intermediate temperature fermentation or high temperature fermentation, a heating means, a temperature control means, etc. are suitably installed in the storage tank 1, the anaerobic processing means 2, the flow path between them (part of the code | symbol X1), etc. It is good (not shown). A well-known thing can be used for a heating means and a temperature control means.

  In the anaerobic circulation channel 21, a fixed bed 22 capable of fixing the methane fermentation microorganism group may be installed. By installing the fixed bed 22 in the anaerobic circulation channel and fixing the methane fermentation microorganism group on the fixed bed 22, the anaerobic treatment capacity can be improved. Thereby, the purification treatment capacity for organic wastewater having a high organic matter content can be greatly improved, and the wastewater treatment can be speeded up or the wastewater treatment facility can be downsized. Moreover, even when there is a large variation in the content of the inflowing organic matter, treated water purified to the same degree can be stably obtained.

  The fixed bed 22 is not particularly limited as long as it is made of a material capable of fixing the methane fermentation microorganism group. For example, aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyolefin fiber, non-woven fabric such as felt, non-woven fabric such as felt, carbon fiber composed of acrylic fiber, etc. Nonwoven fabrics, polyester cotton, and the like are preferable because they are porous and easily adhere to microorganisms, and are relatively inexpensive and easy to install.

  A known means for circulating the wastewater 23 supplied into the anaerobic circulation channel 21 can be used, and is not particularly limited. For example, as shown in FIG. 1, the circulating water may be formed by rotating a stirring blade or the like, or the stored water may be circulated by a known liquid circulating means such as a pump (not shown). The circulation means 23 may be installed at one place or may be installed at a plurality of places. Further, the position and orientation of the circulation means 23 may be set as appropriate so that the stored water is circulated in a certain direction.

  The aerobic treatment means 3 includes a circulating water channel (endless water channel) 31. By circulating the organic wastewater / anaerobic treated water in the circulation channel 31 while aeration, the aerobic microorganisms decompose organic substances.

  The aerobic treatment means 3 only needs to form a circulation channel, and the shape, material, size, depth, etc. thereof are not particularly limited. For example, as described above, the predetermined groove may be formed of reinforced concrete.

  In the aerobic circulation channel 31, a fixed bed 32 on which aerobic microorganisms can be fixed may be installed. Similarly to the above, by installing a fixed bed 32 in the aerobic circulation channel 31 and fixing aerobic microorganisms on the fixed bed 32, the aerobic treatment capacity can be improved. In addition, anaerobic treatment (methane fermentation treatment) and aerobic treatment (treatment by the oxidation ditch method) are continuously performed, and either or both fixed beds 22 and 32 are installed to purify organic wastewater. The processing capacity can be further greatly improved.

  The fixed bed 32 is not particularly limited as long as it is made of a material capable of fixing aerobic microorganisms. For example, as above, aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyolefin fiber, woven fabric / nonwoven fabric made of felt, etc. Nonwoven fabric such as felt, carbon fiber made of acrylic fiber, etc. Nonwoven fabrics and polyester cotton blended with fibers are suitable because they are porous and easily adhere to microorganisms, and are relatively inexpensive and easy to install.

  As the circulation means 33 of the waste water supplied into the aerobic circulation water channel 31, a publicly known one can be used, and it is not particularly limited. For example, similarly to the above, circulating water may be formed by rotating a stirring blade or the like, or the stored water may be circulated by known liquid circulation means such as a pump (not shown). The circulation means 33 may be installed at one place, or may be installed at a plurality of places. The position and orientation of the circulation means 33 may be set as appropriate so that the stored water is circulated in a certain direction.

  In the aerobic treatment means 3, an aeration means 34 is provided in the aerobic circulation channel 31 in order to maintain an aerobic condition. A well-known thing can be employ | adopted for the aeration means 34. FIG. Further, the stored water may be circulated by the liquid circulation means 33 and aerated. However, in FIG. 1, for example, aerobic microorganisms are growing by installing the fixed bed 32 in the aerobic circulation channel. Therefore, in order to maintain a high purification treatment capacity, it is necessary to maintain the dissolved oxygen at a high level. Therefore, it is preferable to install the aeration means 34 separately to sufficiently supply oxygen to the stored water.

  As described above, the organic wastewater treatment system A shown in FIG. 1 includes both the anaerobic treatment means 2 (methane fermentation treatment) and the aerobic treatment means 3 (treatment by the oxidation ditch method).

  By performing anaerobic treatment by methane fermentation and aerobic treatment by oxidation ditch method, the operation management operation is simple. Stable organic matter even if the amount of water and quality of the influent wastewater vary over time. The ability to purify organic wastewater while maintaining the advantages of the oxidation ditch method, such as the ability to remove, reduce the amount of sludge generated, and reduce the amount of aeration, so that maintenance costs can be reduced. This can be further improved. Therefore, compared with the wastewater treatment by the conventional methane fermentation method or oxidation ditch method, the wastewater treatment facility itself can be further downsized while maintaining the same treatment capacity.

  FIG. 2 is a schematic diagram showing another example of the organic wastewater treatment system according to the present invention.

  The organic wastewater treatment system A ′ shown in FIG. 2 includes anaerobic treatment means 2 that circulates organic wastewater in the anaerobic circulation channel 21 while aeration and causes the methane fermentation microorganism group to undergo anaerobic treatment. In the sex circulation channel 21, a fixed bed 22 capable of fixing methane fermentation microorganisms is installed.

  In the organic wastewater treatment system A ′ shown in FIG. 2, the organic wastewater is supplied to the anaerobic treatment means 2 (see symbol X1) and circulates in the circulation channel 21 (see symbol X2). In that case, the anaerobic process by methane fermentation is performed, organic substance is decomposed | disassembled, and the biogas generated by methane fermentation is collect | recovered (refer code | symbol Y1). Through the above process, treated water that has been purified is obtained (see symbol X3). The circulation means 23 is the same as that shown in FIG.

  The installation location of the fixed floor 22 is not particularly limited. For example, as in FIG. 1, it may be installed on the peripheral wall surface of the circulating water channel 21, or a fixed floor installation surface may be separately provided in the circulating water channel 21, and the fixed floor 22 ′ may be installed there.

  The installation method of the fixed floor 22 is not particularly limited. For example, it may be installed by placing or sticking on the peripheral wall surface or fixed floor installation surface of the circulating water channel 21, or a frame or plate-like body in which the fixed floor 22 is previously installed is installed in the circulating water channel. It may be fixed.

  It should be noted that the installation location and installation method of the fixed floor can also be applied to the installation of the fixed floor 32 in the aerobic processing means 3 shown in FIG.

<About the organic wastewater treatment method according to the present invention>
The organic wastewater treatment method according to the present invention will be described below.

  The organic wastewater treatment method according to the present invention includes an anaerobic treatment step (first step) in which organic wastewater is circulated in a substantially sealed anaerobic circulation channel and subjected to methane fermentation as a pre-treatment of the aerobic treatment step. And an aerobic treatment step (second step) in which anaerobic treated water or organic waste water is circulated while aerated to decompose an organic substance into an aerobic microorganism. However, the organic wastewater treatment method including only either the first step or the second step is also widely included in the present invention, and the present invention is not limited to the one including both the first step and the second step.

  In the anaerobic treatment step (first step), as a pre-treatment of the aerobic treatment step (second step), methane fermentation of organic wastewater is performed in the anaerobic circulation channel, and the organic matter in the wastewater is decomposed. Collect the generated biogas as an energy resource.

  By performing anaerobic treatment as a pre-treatment of the aerobic treatment step, biogas can be generated from wastewater, and the purification treatment capacity for organic wastewater in the entire system A can be greatly improved.

  Moreover, construction cost and operation cost can be reduced by performing both anaerobic treatment and aerobic treatment in the circulation channel.

  In the anaerobic circulation channel, a fixed bed capable of fixing the methane fermentation bacteria group may be installed. An anaerobic treatment capacity can be improved by installing a fixed bed in the anaerobic circulation channel and fixing a group of methane fermentation bacteria on the fixed bed. Thereby, the purification processing capability with respect to organic wastewater with high organic substance content can be improved significantly. Moreover, even when there is a large variation in the content of the inflowing organic matter, treated water purified to the same degree can be stably obtained.

  Subsequently, in the aerobic treatment process (second process), organic wastewater and anaerobic treated water are circulated while aerated in the aerobic circulation channel, and organic matter is decomposed into aerobic microorganisms, thereby purifying wastewater. I do.

  In the aerobic circulation channel, a fixed bed capable of fixing aerobic microorganisms may be installed. As described above, the aerobic treatment capacity can be improved by installing a fixed bed in the aerobic circulation channel and fixing aerobic microorganisms on the fixed bed. In addition, the anaerobic treatment (methane fermentation treatment) and the aerobic treatment (treatment by the oxidation ditch method) are continuously performed, and a fixed bed is installed in one or both of the circulation channels, so that organic wastewater can be treated. The purification treatment capacity can be further greatly improved.

  As described above, by performing anaerobic treatment (methane fermentation treatment) and aerobic treatment (treatment by oxidation ditch method) continuously, the operation management operation is simple. Retains the advantages of the oxidation ditch method, such as stable organic removal even with global fluctuations, reduced sludge generation, and reduced maintenance costs due to less aeration. In addition, the purification capacity for organic wastewater can be further greatly improved. Therefore, compared with the wastewater treatment means by the conventional oxidation ditch method, the wastewater treatment facility itself can be further reduced in size while maintaining the same treatment capacity.

  In Example 1, the performance test of the organic wastewater treatment according to the present invention was performed using the wastewater generated in the distilled liquor manufacturing process.

  The following was produced as a prototype model of the organic wastewater treatment system. Manufactures 6L-volume, almost sealed anaerobic circulation channels and 6L-size aerobic circulation channels, installs agitators in both circulation channels, and installs aeration equipment in the aerobic circulation channels, anaerobic aerobic treatment The prototype model. In addition, a polyethylene non-woven fabric was installed as a fixed bed on the walls of both circulation channels, and a prototype model of fixed bed anaerobic aerobic treatment was used.

  To each of these prototype models, the wastewater generated in the distilled liquor production process (see Table 1 below for the influent water quality and load factor) is supplied and treated in an anaerobic circulation channel for 8 days (1st Treatment) Next, the water was treated in an aerobic circulation channel for 8 days (second treatment), and the water quality was measured.

Tables 1 and 2 show the results of water quality measurement. Table 1 shows the results of water quality measurement in a prototype model of anaerobic aerobic treatment, and Table 2 shows the results of water quality measurement in a prototype model of fixed-bed anaerobic aerobic treatment. In the table, “COD Cr” is the chemical oxygen demand measured using potassium dichromate and “SS” is the suspended matter (Suspended)
solids) and “VSS” represent volatile suspended solids, respectively. In the table, “Influent water quality” is the quality of the wastewater used in the test, “Load factor” is the value of the wastewater supplied to the wastewater treatment system, converted to the value per day, and “After anaerobic treatment” is after the first treatment. “After aerobic treatment” represents the water quality after the first treatment and the second treatment, respectively.

The decomposition rates calculated from Tables 1 and 2 are shown in Tables 3 and 4. Table 3 shows the decomposition rate in the prototype model of the anaerobic aerobic treatment, and Table 4 shows the decomposition rate in the prototype model of the fixed-bed anaerobic aerobic treatment. In the table, “decomposition rate after the first treatment” is the decomposition rate of the organic matter after the first treatment when compared with the waste water before treatment (inflow water quality), “decomposition rate of the first to second treatment” is the first The degradation rate of the organic matter after the second treatment when compared with the treated water after one treatment, and the “total degradation rate” is after the first treatment and second treatment when compared with the wastewater before treatment (inflow water quality) Represents the decomposition rate of organic matter.

  As shown in Tables 1 and 3, when organic wastewater having an influent water quality of 16,600 mg / L is subjected to anaerobic treatment in a circulation channel for 8 days of hydraulic residence time, for example, the decomposition rate in COD Cr is 73 3%. This value is almost equivalent to the processing capacity in ordinary methane fermentation using a digester. On the other hand, as described above, construction cost and operation cost can be reduced by performing methane fermentation in the circulation channel. Therefore, this result suggests that the construction cost and the operation cost can be reduced by performing the anaerobic treatment in the circulation channel, and the treatment capacity almost equal to that in the case of normal methane fermentation can be maintained.

  Moreover, as shown in Table 2 and Table 4, when the nonwoven fabric made from polyethylene was installed as the fixed bed on the wall surface of the anaerobic treatment circulation channel, for example, the decomposition rate in COD Cr was 93.0%. This result shows that the methane fermentation treatment capacity can be greatly improved by installing a fixed bed capable of fixing the methane fermentation microorganism group in the anaerobic circulation channel.

  On the other hand, as shown in Tables 1 and 3, when the anaerobic treatment and the aerobic treatment were continuously performed (anaerobic aerobic treatment), for example, the decomposition rate in COD Cr was 91.1%. This result shows that the methane fermentation treatment capacity can be greatly improved by performing the aerobic treatment in the circulation channel as the latter stage treatment of the anaerobic treatment.

  Moreover, as shown in Table 2 and Table 4, when a nonwoven fabric was installed in both circulation channels (fixed-bed anaerobic aerobic treatment), for example, the decomposition rate in COD Cr was 99.3%. This result shows that the purification treatment capacity for organic wastewater can be further greatly improved by continuously performing the fixed bed methane fermentation treatment and the treatment by the fixed bed oxidation ditch method.

  In addition, the biogas recovery amount obtained in the anaerobic treatment of this test was about 1 NL / L-reactor / day, the methane concentration in both the case where the nonwoven fabric was installed in both circulation channels and the case where the nonwoven fabric was not installed. Was about 60%.

  In Example 2, the organic material load was increased and the performance test of the organic wastewater treatment according to the present invention was performed.

  As in Example 1, a 6-L approximately sealed anaerobic circulation channel and a 6-L aerobic circulation channel were created, and a stirrer was installed in both circulation channels, and an aeration device was installed in the aerobic circulation channel Then, a non-woven fabric made of polyethylene was installed on the wall surfaces of both circulation channels to make a prototype model of fixed-bed anaerobic aerobic treatment.

  This prototype model is supplied with the wastewater generated in the distilled liquor manufacturing process (see Table 5 below for influent water quality and load factor) and treated in an anaerobic circulation channel for 3 days in the hydraulic retention time (first treatment) Then, the hydrological residence time was treated for 3 days in the aerobic circulation channel (second treatment), and the water quality was measured.

Table 5 shows the results of water quality measurement. Table 5 shows the result of water quality measurement when wastewater with a high organic content is subjected to fixed-bed anaerobic aerobic treatment. Each item in the table is the same as in Table 1 or Table 2.

Table 6 shows the decomposition ratio calculated from Table 5. Each item in the table is the same as in Table 3 or Table 4.

  As shown in Tables 5 and 6, by performing the fixed-bed anaerobic aerobic treatment according to the present invention, a sufficient amount of organic matter could be decomposed even with wastewater with a high organic matter load. This result shows that the purification treatment capacity for organic wastewater can be further greatly improved by continuously performing the fixed bed methane fermentation treatment and the treatment by the fixed bed oxidation ditch method.

  Note that the biogas recovery amount obtained in the anaerobic treatment of this test was about 3.65 NL / L-reactor / day, and the methane concentration was about 60%.

  In Example 3, waste water having the same water quality as in Example 2 was supplied to the prototype model similar to that in Example 2, and the hydraulic residence time at which the decomposition rate of COD Cr was 90% or more of the influent water quality was calculated. . In addition, when only the aerobic treatment was performed in the aerobic circulation channel having no fixed bed, the decomposition rate of CODCr did not become 90% or more of the influent water quality.

The results are shown in Table 7. Table 7 shows the hydraulic residence time when the purification treatment is performed under each condition. In the table, “anaerobic treatment / no fixed bed + aerobic treatment / no fixed floor” means anaerobic treatment without an aerobic treatment after anaerobic treatment in an anaerobic circulation channel without a fixed bed. The result of aerobic treatment in the circulation channel is the result of “anaerobic treatment only with fixed bed” when anaerobic treatment is performed in the anaerobic circulation channel with a fixed bed and no aerobic treatment is performed. The result is that “anaerobic treatment with fixed bed + aerobic treatment with fixed bed” is an anaerobic circulation channel with a fixed bed and then an anaerobic circulation channel with a fixed bed. The results when the tempering process is performed are respectively shown. The number of days in the table represents the hydraulic retention time, and represents the number of days for which anaerobic treatment was performed, the number of days for which aerobic treatment was performed, and the total hydraulic residence time, respectively.

  As shown in Table 7, by performing anaerobic treatment and aerobic treatment, even in the case of organic wastewater with a high organic matter content, the organic matter can be reduced to 90% or more of the influent water quality at a value of CODCr within a predetermined period. I was able to break it down. In addition, by installing a fixed bed in the anaerobic circulation channel, and by installing a fixed bed in both the anaerobic circulation channel and the aerobic circulation channel, the hydraulic residence time can be significantly shortened.

1 is a schematic diagram showing an example of an organic wastewater treatment system according to the present invention. The schematic schematic diagram which shows another example of the organic wastewater treatment system which concerns on this invention.

DESCRIPTION OF SYMBOLS 1 Storage tank 2 Anaerobic treatment means 21 Anaerobic circulation channel 22 Fixed bed 23 Circulation means 3 Aerobic treatment means 31 Aerobic circulation channel 32 Fixed bed 33 Circulation means 34 Aeration means A, A 'Organic wastewater treatment system

Claims (8)

An organic wastewater treatment system that purifies organic wastewater using microorganisms,
An organic wastewater treatment system equipped with anaerobic treatment means for circulating organic wastewater in a substantially sealed anaerobic circulation channel and performing methane fermentation.   The organic wastewater treatment system according to claim 1, wherein a fixed bed capable of fixing methane fermentation microorganisms is installed in the anaerobic circulation channel. As a subsequent process of the anaerobic process,
The organic wastewater treatment system according to claim 1, further comprising aerobic treatment means for circulating the anaerobic treated water in the aerobic circulation channel while aeration, and decomposing organic substances into aerobic microorganisms.   The organic wastewater treatment system according to claim 3, wherein a fixed bed capable of fixing aerobic microorganisms is installed in the aerobic circulation channel.   An organic wastewater treatment method comprising at least an anaerobic treatment step in which organic wastewater is circulated in a substantially sealed anaerobic circulation channel and subjected to methane fermentation.   The organic wastewater treatment method according to claim 5, wherein a fixed bed capable of fixing methane fermentation bacteria is installed in the anaerobic circulation channel. As a subsequent process of the anaerobic treatment process,
The organic wastewater treatment method according to claim 5, comprising at least an aerobic treatment step in which the anaerobic treatment water is circulated while aerated to decompose an organic substance into an aerobic microorganism.   The organic wastewater treatment method according to claim 7, wherein a fixed bed capable of fixing the aerobic microorganism is installed in the aerobic circulation channel.

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