JP5021902B2 - Organic wastewater treatment facility and treatment method - Google Patents

Description

  The present invention relates to an organic wastewater treatment facility and treatment method, and more particularly, to an organic wastewater treatment facility and method comprising at least one biological treatment tank and a fixed filter bed inside the biological treatment tank. .

  As an organic wastewater treatment facility, water treatment methods with a fixed filter bed inside include anaerobic filter bed method, aerobic filter bed method, catalytic oxidation method, activated sludge method fixed filter bed method, etc. Yes.

  The anaerobic filter bed method is described in Non-Patent Document 1 below, for example. That is, on page 58, line 13 to line 16 of Non-Patent Document 1, “The function of the anaerobic filter bed tank is to separate solids contained in the inflowing sewage and separate the solids for a certain period of time. In addition, the characteristics of an anaerobic filter bed tank can be expected to have an inclined plate effect and a filtration effect when separating solids by filling the tank with a filter medium, and an anaerobic biofilm on the surface of the filter medium. The removal of BOD and the reduction of sludge can be expected depending on the work. "The advantages of the anaerobic filter bed method are described.

On the other hand, in the 17th to 19th lines of the same non-patent document 1, “BOD removal has a stable removal effect depending on the type of filter medium to be filled and the use conditions. The BOD removal rate in the anaerobic filter bed tank is treated as 0% in terms of structural standards.
Is described. Also, the reason for this is that the structure standard does not provide any specific provisions regarding the type of filter medium to be filled, and the range of use conditions is notable, so the removal rate is not expected in the design of the contact aeration tank. Is safe ".

  Actually, the BOD value of the treated water from the anaerobic filter bed equipment is high, and it is impossible to discharge the treated water of the anaerobic filter bed directly into the river by providing it in the previous stage as a pretreatment for the aerobic treatment.

Septic tank maintenance and management 2nd edition (issued by the Japan Environmental Education Center)

The aerobic filter bed method is described in Non-Patent Document 2 below, for example. That is, in Non-Patent Document 2, page 241 lines 12 to 13, "the aerobic microorganism adsorption action, biodegradation action, physical filtration work by flowing down between the filter media synergistically, in a short time Advantages such as “good treated water can be obtained” are described. And in this aerobic filter bed method, it is possible to perform processing in a high filter medium density with a structure in which filter media such as pebbles are densely laid while increasing the volume load up to 2 kg BOD / m ³ · day. .

  However, according to the aerobic filter bed method, it is necessary to keep the whole aerobic, and since sludge and biofilm grow and clog easily, the work is complicated and complicated to remove the sludge. The washing process usually needs to be performed frequently, such as about once a day, and the backwash water needs to be separately subjected to sedimentation separation. Therefore, there are various problems such as a lot of time for dehydration and the like and an increase in sludge treatment costs.

Sewerage facility planning / design guidelines and commentary (Japan Sewerage Association)

Further, the contact oxidation method is also described in Non-Patent Document 2. In other words, in line 25 to line 26 of page 237 of Non-Patent Document 2, “Adopting a contact material with a large specific surface area and maintaining a large amount of attached organisms, it can flexibly cope with fluctuations in the inflowing substrate. Advantages such as “can be done” are described. However, according to the description of Non-Patent Document 2, the BOD volumetric load is based on about 0.3 kg / m ³ · day, and the contact material filling rate which is a fixed filter bed is about 55%. In addition, the possibility that the filter medium is clogged with sludge and the necessity of backwashing equipment are also described.

Some septic tanks use the same method as the contact oxidation method, and are described as the contact aeration method on pages 84 to 99 of Non-Patent Document 1. On page 89 of Non-Patent Document 1, the BOD volumetric load is 0.5 kg / m ³ · day or less (notice 2) in the small merged treatment septic tank, and the BOD volumetric load is 0. 3kg / m ³ · day or less (notifications 3 and 6) is described, and on page 91, the filling rate of the contact material used in these septic tanks is as follows. It is stated that it is generally 55% and 55% or more in the merged septic tank.

  As described above, the contact material filling rate can be 55% or more by the contact oxidation method or the contact aeration method only in the range where the volume load is very low as described above. Membranes and sludge may accumulate inside the contact material and become clogged. For this reason, Non-Patent Document 1 describes a facility for backwashing, and attention is paid to the backwashing method. Furthermore, after backwashing, the facility for transferring sludge that is peeled off from the filter medium and accumulated in the tank. And methods are also described.

  As described above, in the contact oxidation method and the contact aeration method, it is necessary to perform backwash regularly, such as once or twice a week, and in order to avoid sludge blockage, BOD volume load or contact material filling There is a problem that the rate must be reduced, and as a result of these restrictions, the amount of processing is reduced, and in order to prevent this, a large-scale facility treatment is required. Furthermore, it requires time and labor for sedimentation and separation of sludge transferred from the tank after backwashing, extraction of the sludge out of the system, coagulation dehydration, disposal of the sludge, etc. It was.

A method similar to a normal activated sludge method, in which the concentration of floating sludge is relatively high, for example, 2000 mg / l or more, and a method of installing a filter medium is called a fixed filter bed method or an activated sludge method. However, in these methods, sludge is more likely to clog than in the contact aeration method, so the filter media is formed in a “ribbon”, “string” or “bunch” shape that is less likely to clog. The specific surface area was as low as 60 m ² / m ³ or less, and the packing rate of the filter medium had to be lowered.

  In addition, various measures are taken with respect to the air diffusion method so that air bubbles hit the filter medium from below or the filter medium is washed with a stream of air diffused so as not to be clogged with sludge and to prevent the entire interior from being spoiled. ing. However, this method has a condition that the surface area of the filter medium is low, and the filling rate of the filter medium is lowered and the sludge concentration is increased. Therefore, a large sedimentation tank corresponding to the concentration is required, and the standard activated sludge method is used. It will be similar to equipment and operating conditions.

  In the contact aeration method and the fixed filter bed method, sludge accumulates on the filter medium, and the sludge often peels off from the filter medium due to the generation of bubbles in the inside, and the sludge concentration changes rapidly and the sludge settles. As a result, it was necessary to make more detailed handling of the operating conditions. Therefore, the settling property and treatment status of the sludge are monitored, the operation method is dealt with, and complicated operations such as drawing out the generated sludge and dehydrating treatment are involved.

  In the treatment facility using the filter medium, the sludge on the filter medium is the basis of the process, and more efficient treatment is possible by increasing the specific surface area of the filter medium and the filling rate of the filter medium. However, the conventional equipment and methods have a decisive problem of clogging due to the accumulation of sludge on the filter medium. Therefore, it is necessary to reduce the volume load of the BOD or reduce the specific surface area and packing rate of the filter medium. In addition, it requires complicated work such as periodic backwashing, or requires monitoring and operation to maintain a high-concentration sludge interface. Since problems such as disposal are also caused, the water treatment work is troublesome.

  The present invention was made to solve all of the above problems, and was said to be difficult in the biological treatment of the activated sludge method fixed filter bed method and the contact aeration method in the treatment equipment for organic wastewater, Using a filter medium with a high specific surface area, increasing the filter medium packing rate, increasing the BOD volumetric load of the equipment to increase the BOD removal efficiency, solving the internal clogging problem due to sludge and eliminating the time-consuming backwash process Another object of the present invention is to provide an organic wastewater treatment facility and a treatment method capable of purifying wastewater in a state where there is almost no generation of excess sludge.

The present invention was made as an organic wastewater treatment facility and treatment method in order to solve such problems, and the invention according to claim 1 according to the organic wastewater treatment facility is characterized by at least two or more biological treatments. An organic wastewater treatment facility equipped with a tank, wherein a fixed filter bed is installed in a biological treatment tank corresponding to a capacity equivalent to at least 1/2 or more of the total capacity of the at least two biological treatment tanks, Of the at least two or more biological treatment tanks, the front biological treatment tank is an aerobic aeration tank not provided with a fixed filter bed, and a fixed filter bed is provided on the rear side of the aerobic aeration tank. A biological treatment tank is provided, and in the biological treatment tank in which the fixed filter bed is installed, air bubbles that are diffused in an aqueous layer portion where no fixed filter bed is present do not directly hit the filter medium in the fixed filter bed. The stationary filter bed is provided with a bubble blocking wall. The filter medium of the stationary filter bed has a specific surface area is formed as a skeleton-like spherical filter medium such that 60~100m ² / m ^3, and the filter media filling rate of relative tank volume of the fixed filter bed biological treatment tank which is installed Is 70-90% by volume , and the capacity load for all the biological treatment tanks in which the fixed filter bed is installed and in the biological treatment tank in which the fixed filter bed is not installed is 0.6 kg BOD / m ³ · day-2. It is configured to be 5 kg BOD / m ³ · day .

Further, the invention of claim 2, wherein according to the method of treating organic waste water is a method of treating organic waste water to process the organic waste water processing facility organic wastewater having two or more biological treatment tanks even without least A fixed filter bed is installed in a biological treatment tank corresponding to a capacity of at least 1/2 or more of the total capacity of the at least two biological treatment tanks. The biological treatment tank on the front side is an aerobic aeration tank not equipped with a fixed filter bed, a biological treatment tank equipped with a fixed filter bed is provided on the rear side of the aerobic aeration tank, and the fixed filter bed is installed. In the biological treatment tank, aeration is performed in the water layer portion where no fixed filter bed exists, and a bubble blocking wall is provided in the fixed filter bed so that the bubble does not directly hit the filter medium in the fixed filter bed, The filter medium of the fixed filter bed has a specific surface area of 60 to 100 m. Formed as a scaffold-like spherical filter medium such that ² / m ^3, and the filter media filling rate of relative tank volume of the fixed filter bed the installed biological treatment tank while the 70 to 90 volume%, the fixed filtration Organic so that the capacity load of all biological treatment tanks with a floor installed and biological treatment tanks without a fixed filter bed is 0.6 kg BOD / m ³ · day to 2.5 kg BOD / m ³ · day It is characterized by treating wastewater.

  The sludge accumulation does not prevent the blockage of sludge unless the sludge condition changes significantly, but the sludge hardly changes under aerobic conditions that contain some oxygen. If sludge that accumulates a lot is subjected to conditions up to anaerobic digestion, sludge is liquefied by anaerobic decomposition (decomposition to low molecular acids as previously known) and sludge volume reduction by anaerobic digestion. Can escape from sludge blockage. However, under half-way anaerobic conditions, sludge liquefaction occurs to some extent, but it is close to rot, and usually has a negative effect such as bulking phenomenon and worsening of treated water.

Therefore, in the invention described in claim 1 and in the invention described in claim 7, a condition that is different from the conventional common sense condition disclosed in Non-Patent Document 1 and Non-Patent Document 2 is set. By strongly promoting the anaerobic situation, it was possible to liquefy or reduce the volume of sludge deposited on fixed filter beds and contact aerated filter media without causing the conventional harmful effects. .

In the invention according to claim 1 and claim 7, the specific surface area of the filter medium is set to 60 to 100 m ² / m ^{3. When} the specific surface area is less than 60 m ² / m ³ , sludge is sufficiently accumulated. This is because anaerobic conditions are unlikely to occur because it is not possible, and when the specific surface area exceeds 100 m ² / m ³ , sludge may be clogged.

  The reason why the filling rate of the filter medium with respect to the tank volume of the biological treatment tank is set to 70 to 90% by volume is that the filling rate of the filter medium is larger than the set values disclosed in the conventional Non-Patent Document 1 and Non-Patent Document 2. This is to make it possible to collect a large amount of sludge by setting it to 70% by volume or more, and the reason why it is set to 90% by volume or less may be that aeration and stirring may be required in the water layer around the filter medium. This is because when it exceeds 90% by volume, there is a possibility that the sludge may be blocked. Here, “with respect to the tank volume of the biological treatment tank” means that a fixed filter bed, which is a main treatment tank that occupies at least half or more of all the treatment tanks, is installed, excluding the aerobic aeration tank on the front side. It is a calculated value only for the biological treatment tank.

Furthermore, the capacity load on all the tanks of the biological treatment tank in which the fixed filter bed 4 is installed and the biological treatment tank in which the fixed filter bed 4 is not installed is 0.6 kg BOD / m ³ · day to 2.5 kg BOD / m ³ · It is preferable to set the date. If the capacity load is less than 0.6 kg BOD / m ³ · day, the oxygen deficient state does not increase inside the fixed filter bed, so it is not always easy to cause anaerobic digestion. This is because the filter bed may be clogged, and when it is 2.5 kg / m ³ · day or more, the treatment may be difficult. However, it is also possible to perform the treatment in a state where the capacity load is outside the range of 0.6 kgBOD / m ³ · day to 2.5 kgBOD / m ³ · day.

This BOD volumetric load excludes raw water tanks that store raw water flowing in or prevent fluctuations in the raw water, and excludes biological treatment tanks equipped with a fixed filter bed as described above and organisms equipped with the fixed filter bed. A biological treatment tank such as an aerobic aeration tank provided on the front side of the treatment tank is included. Therefore, if it is calculated only with a biological treatment tank equipped with a fixed filter bed, the volume load becomes high, and it is about 1 kg / m ³ · day or more, which is 2 to 4 times higher than that of normal contact aeration. It has become. When the inflow load increases, the BOD value of the treated water in the facility of the present invention becomes higher. Therefore, when the BOD volume load is close to 2 kg / m ³ · day, the facility is configured to discharge the treated water into the sewer. Suitable for

  The shape of the filter medium is not particularly limited. For example, a string-like or ribbon-like one is not preferable because a strong anaerobic situation is hardly obtained inside. Also, the accumulated sludge is often separated from the location due to the occurrence of bubbles such as methane from the inside, so it is preferable to use a shape that allows the filter medium to receive the separated sludge, such as a shape that has an upward dish structure. Although it can be used, a deep cylindrical shape like a small cylinder is difficult to move even if the sludge fluidity is improved, and it is easy to collect in the filter medium, so sludge is likely to clog, and in a preferred shape Absent. From such a viewpoint, a skeleton-like spherical filter medium as defined in claim 3 or a skeleton-like spherical filter medium having a shape similar to the shape is preferable. As long as the filter medium has the same effect, a filter medium having a shape such as a regular octahedron, a regular dodecahedron, or a saddle shape can also be used.

  In addition, since it is preferable that the water layer around the fixed filter bed 4 has a certain amount of oxygen, aeration is performed in the water layer as described in claim 4. In order to make the inside into a strong anaerobic condition, it is desirable not to directly apply air bubbles to the filter medium 8, and an air bubble blocking wall 5 such as a metal or plastic plate is provided on the fixed filter bed 4, Is preferably blocked. Even when aeration is performed by aeration, it is necessary to keep the inside of the fixed filter bed 4 in an anaerobic condition by gentle agitation.

  In order to make the soluble BOD sludge, it is desirable to aerate the raw water in the presence of some sludge and oxidize it on the front side of the biological treatment tank equipped with a fixed filter bed. A tempered aeration tank 1 is provided. A filter medium may be installed in the aerobic aeration tank 1, but it is not necessary to have a filling rate as in the biological treatment tank provided with the fixed filter bed 4 as described above, and an amount much smaller than 70% may be used. Good. Further, from the viewpoint of economy, the aerobic aeration tank 1 may be a tank without a filter medium. Even when a filter medium is provided, the capacity of the entire tank should be at most ½ or less. If this capacity is increased too much, the sludge is oxidized, and the fixed filter bed in the biological treatment tank in the latter stage is used. Anaerobic digestion is less likely to occur inside.

In the present invention, a portion of the sludge that has been anaerobically decomposed inside the fixed filter bed 4 is discharged, and the BOD value of the treated water in the middle may be increased. It is preferable to process in multiple stages. Specifically, it is preferable to provide four or more biological treatment tanks as described in claim 6, and more preferably six or more stages. When biological treatment tanks equipped with fixed filter beds are provided in multiple stages, sludge and SS remain slightly in the final biological treatment tank, but the sludge concentration in the final biological treatment tank is not high. Even if the floor is not provided, a small separation tank is sufficient. It is also possible to return sludge or a small amount several times to several tens of times a day from such a separation tank to the aerobic aeration tank 1 for reuse. In this case, the sludge separated in the separation tank becomes seed sludge for the aerobic aeration tank 1.
In addition, there is virtually no sludge to be discharged.

  In addition, a processing tank equipped with a fixed filter bed having a considerably smaller volume than that of the main biological treatment tank can be installed as a final finish on the rear side of such a separation tank.

  In order to make the inside of the fixed filter bed 4 anaerobic, it is desirable that the oxidation-reduction potential value of −350 mV or less, which is the methane generation region, but it is usually difficult to measure the internal state. Any evidence of methane generation is sufficient. The generation of methane can be confirmed by stopping the aeration, collecting bubbles generated from the bottom after a few minutes, and analyzing the contents.

  The type of waste water targeted by the present invention is not particularly limited, and the present invention can be applied to waste water from various manufacturing plants, food processing waste water, village waste water, septic tank waste water, livestock related waste water, and the like.

As described above, in the present invention, a large amount of sludge is accumulated by setting the specific surface area of the filter medium in the fixed filter bed to 60 to 100 m ² / m ³ and the filling rate of the filter medium to 70 to 90% by volume. Thereby increasing the oxygen deficiency inside the fixed filter bed, and as a result, it is possible to make it easy to cause anaerobic digestion, which would normally be blocked However, without backwashing, the facility can be operated smoothly without causing clogging, and clean treated water can be obtained with almost no generation of excess sludge. effective.

  Compared with the conventional contact aeration method, the BOD volumetric load is more than doubled, which means that more efficient processing can be performed with less than half of the conventional equipment, greatly increasing the cost of equipment construction compared to the conventional method. Since the excess sludge is hardly discharged, the operating cost of the facility can be greatly reduced.

  Furthermore, by setting conditions that are different from conventional common-sense conditions and strongly promoting anaerobic conditions, sludge deposited on fixed filter beds and contact aerated filter media will cause the same harmful effects as before. Therefore, it can be liquefied or reduced in volume, and the treatment equipment as a whole can be made more efficient, and sludge can be reduced at the same time by operating in the actual equipment.

  As described above, according to the present invention, the treatment efficiency is increased, the treatment facility is reduced, and the wastewater that is difficult to be treated by the conventional activated sludge method can be treated by partially including the aerobic treatment and the anaerobic treatment. In addition, since the amount of aeration is small, the power consumption is low, and there is almost no excess sludge discharge as described above. In addition, there is no need to monitor the sludge interface, greatly reducing the labor of operation management. Possible facilities can be obtained. Incidentally, in the present invention, surplus sludge is not generated, or the amount of sludge discharged from the facility can be 10% or less of the amount of sludge discharged from a general activated sludge facility.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic block diagram of an organic wastewater treatment apparatus according to an embodiment, and FIG. 2 is a schematic perspective view of a biological treatment tank in the treatment facility of FIG. The organic wastewater treatment apparatus of the present embodiment includes an aerobic aeration tank 1 on the front stage side, a total of eight stages of biological treatment tanks 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, and separation at the final stage. A tank 3 is provided.

  In the respective biological treatment tanks 2a, 2b,... 2h, as shown in FIGS. On the side of the fixed filter bed 4, an air bubble blocking wall 5 made of an iron plate is provided, and stainless steel meshes 6 and 7 are provided at the upper and lower portions thereof. The fixed filter bed 4 is filled with a large number of filter media 8. In the present embodiment, a large number of filter media 8 are packed in the fixed filter bed 4 so that the filling rate of the filter media 8 occupies 70 to 90% in the entire space of the biological treatment tanks 2a, 2b,.

  Further, an aeration tube 9 is provided in the approximate center of each biological treatment tank 2a, 2b,. The position of the air diffuser 9 a provided at the lower end of the air diffuser 9 is set so as not to fall below the lower end of the air bubble blocking wall 5. In the state seen from the front side of the facility, as shown in FIG. 1, only one aeration tube 9 is shown in the approximate center of each biological treatment tank 2a, 2b,... 2h. As shown in FIG. 3, three diffuser tubes 9, 9, 9 are provided side by side in a direction intersecting with the fixed filter beds 4, 4 on both sides.

  The aerobic aeration tank 1 does not have a fixed filter bed, and has a configuration in which an aeration tube 9 is simply disposed. Specifically, three diffuser tubes 9, 9, 9 are provided as seen from the front side of the facility as shown in FIG. The aerobic aeration tank 1 is a general aeration tank that sludges soluble organic matter with microorganisms. The sludge is intermittently returned to the aerobic aeration tank 1 from a separation tank 3 described later as seed sludge. A small amount is added, raw water is mixed and aerated, and sludge composed of bacteria and other organisms is formed. The separation tank 3 also has no fixed filter bed, and is a general precipitation separation tank that performs solid-liquid separation between solids such as sludge and treated water.

  In each biological treatment tank 2a, 2b,... 2h, a transfer pipe 10 for transferring the water to be treated in one biological treatment tank to the next biological treatment tank is provided in each biological treatment tank 2a, 2b,. It is provided to straddle. Moreover, such a transfer pipe 10 is provided from the aerobic aeration tank 1 to the first biological treatment tank 2a and from the final biological treatment tank 2h to the separation tank 3. The aerobic aeration tank 1 is provided with an inflow pipe 12 through which raw water flows, and the separation tank 3 is provided with a return flow path 13 for returning treated water to the aerobic aeration tank 1.

  FIG. 3 is a perspective view showing the filter medium 8 filled in the fixed filter bed 4. As shown in FIG. 3, the filter medium 8 of this embodiment is formed in a skeleton-like spherical shape. More specifically, the filter medium 8 is composed of one lateral member 15 and a total of three longitudinal members 16a, 16b, and 16c. These lateral members 15 and longitudinal members 16a, 16b, and 16c are all plate-like in thickness.

  As shown in FIG. 3, the transverse member 15 has a curved surface like a twisted ridge, and the transverse member 15 is formed with a circular hole 14.

  In addition, the three longitudinal members 16a, 16b and 16c in total have a face extending in the vertical direction, but the two longitudinal members 16a and 16b are arranged in parallel to each other. The other longitudinal member 16c is disposed so as to be orthogonal to the two longitudinal members 16a and 16b. And as for these longitudinal direction members 16a, 16b, and 16c, all have the top part formed in the curve shape. Further, ribs 17 are formed on both sides of the two longitudinal members 16a and 16b that are parallel to each other so as to be orthogonal to the longitudinal members 16a and 16b, and at substantially the center of the other longitudinal members 16c. Also, a rib 18 is formed so as to be orthogonal to the longitudinal member 16c. These ribs 17 and 18 are also formed with a face extending in the vertical direction. Further, a long hole 19 is formed in the longitudinal members 16a, 16b and 16c.

  Next, a method for treating organic wastewater with such an organic wastewater treatment facility will be described. First, raw water is caused to flow into the aerobic aeration tank 1 through the inflow pipe 12. The raw water contains sludge and organic SS. The introduced raw water is aerobically treated in the aerobic aeration tank 1. That is, air flows into the aerobic aeration tank 1 from the diffuser tubes 9, 9, and 9 and aeration agitation is performed.

  Next, the water to be treated that has been aerobically aerated in the aerobic aeration tank 1 flows into the first biological treatment tank 2 a through the transfer pipe 10. Since a diffuser tube 9 is provided in the approximate center of the biological treatment tank 2a, when air flows in from the diffuser 9a of the diffuser pipe 9, the fixed filter bed 4 in the biological treatment tank 2a. So-called aeration agitation is performed in the other water layer portion.

  In this case, since the air bubble blocking wall 5 is provided on the side surface of the fixed filter bed 4, air bubbles are prevented from entering the fixed filter bed 4 from the side surface, and at the lower end of the air diffuser tube 9. Since the position of the provided air diffuser 9 a is set so as not to drop below the lower end of the air bubble blocking wall 5, the bubbles released from the air diffuser 9 a Therefore, it does not enter the fixed filter bed 4 from the lower wire mesh 7.

  Therefore, aerobic processing is performed as a result of aeration agitation in the water layer portion in the biological treatment tank 2a other than the fixed filter bed 4, and air intrusion into the fixed filter bed 4 is prevented as described above. Therefore, anaerobic treatment is performed in the fixed filter bed 4.

In this case, the fixed filter bed 4 is filled with a large number of filter media 8 so as to occupy a very high filling rate of 70 to 90% in the biological treatment tank 2a. As a result, anaerobic decomposition of organic substances and the like is promoted. The filter medium 8 is composed of one transverse member 15 and a total of three longitudinal members 16a, 16b, and 16c as described above, and is formed into a skeleton-like sphere as a whole. The surface area becomes as large as 60 to 100 m ² / m ³ , whereby sludge is more favorably supported and anaerobic decomposition is more efficiently promoted.

In addition, since the filling rate of the filter medium is as large as 70 to 90% as described above, and the specific surface area of the filter medium is as large as 60 to 100 m ² / m ³ , sludge clogging occurs. easy. Nevertheless, sludge blockage is less likely to occur under the conditions described above, and the total capacity load applied to the aerobic aeration tank 1 and the biological treatment tanks 2a to 2h is 0.6 kg BOD / m ^3. · day due to set so that ~2.5kgBOD / m ³ · day, is promoted anaerobic digestion within the fixed filter bed, because volume reduction phenomena of liquefaction phenomenon and sludge sludge by anaerobic decomposition occurs to a preferred It is.

As described above, in the biological treatment tank 2a, the aerobic treatment is performed by aeration agitation in the water layer portion other than the fixed filter bed 4, and the infiltration of air is caused by the air bubble blocking wall 5 in the fixed filter bed 4. Therefore, an anaerobic process is performed in the fixed filter bed 4. In particular, the filling rate of the filter medium 8 packed in the fixed filter bed 4 is very high, about 70 to 90% with respect to the entire volume of the biological treatment tank 2a, and the specific surface area of the filter medium 8 is 60 to 100 m ² / m ^3. Therefore, anaerobic digestion inside the fixed filter bed 4 is promoted, and sludge liquefaction and sludge volume reduction due to anaerobic decomposition are preferably caused.

The treated water treated in the biological treatment tank 2a is supplied to the biological treatment tank 2b in the next stage through the transfer pipe 10. In the biological treatment tank 2 as well, the treatment is performed aerobically and anaerobically as in the biological treatment tank 2a. Also in the biological treatment tank 2b, the filling rate of the filter medium 8 is very high at about 70 to 90% with respect to the biological treatment tank 2b, and the specific surface area of the filter medium 8 is as large as 60 to 100 m ² / m ^3. Therefore, anaerobic digestion inside the fixed filter bed 4 is promoted in the same manner as in the biological treatment tank 2a.

  Furthermore, the water to be treated treated in the biological treatment tank 2b is supplied to the biological treatment tank 2c in the next stage through the transfer pipe 10. In the biological treatment tank 2c, the treatment is performed aerobically and anaerobically as in the biological treatment tanks 2a and 2b. In this way, the water to be treated is sequentially treated in the biological treatment tanks 2c, 2d, 2e, 2f, 2g and 2h, and further transferred from the biological treatment tank 2h in the final stage to the separation tank 3.

  The treated water separated in the separation tank 3 is discharged out of the system and discharged. The solid matter such as sludge separated in the separation tank 3 is returned to the aerobic aeration tank 1 and reused. The treated water separated in the separation tank 3 can be returned to the aerobic aeration tank 1 or the biological treatment tank 2a and circulated without being discharged out of the system.

  In this embodiment, since biological treatment is performed in a total of eight biological treatment tanks, the quality of the treated water is further improved.

The filter medium 8 of the present embodiment is formed to include the three longitudinal members 16a, 16b, and 16c as described above, the transverse member 15 having a twisted curved surface, and the rib 17. Therefore, the specific surface area can be increased to 60 to 100 m ² / m ^3, and sludge can be suitably loaded, but clogging hardly occurs between a large number of filter media 8 and 8 due to the accumulation of sludge. It is also a shape.

  Examples of the present invention will be described below.

Example 1
In this example, the organic wastewater was treated using the treatment apparatus of the embodiment of FIG. The effective volume of all the aerobic aeration tank 1, biological treatment tanks 2a, 2b, ˜2h, and separation tank 3 was set to be about 14 m ^{3 in} total. The volume of the aerobic aeration tank 1 was set to 3 m ^3, and the volume ratio of all the treatment tanks was set to 21%.

The three biological treatment tanks 2a, 2b, and 2c were set so that their effective capacities were 1.5 m ³ , respectively. In the biological treatment tanks 2a, 2b, and 2c, the filter bed portions provided with the fixed filter bed 4 were each 1.1 m ^3, and the volume ratio of the filter bed portion to the biological treatment tank was set to 72%. . In addition, the three biological treatment tanks 2d, 2e, and 2f were set to have an effective capacity of 1.3 m ³ , respectively. The filter bed portions in the biological treatment tanks 2d, 2e, and 2f were set to 1.0 m ³ , respectively, and the volume ratio of the filter bed part to the biological treatment tank was set to 75%.

Furthermore, the biological treatment tank 2g was set to have an effective capacity of 1.1 m ³ , the filter bed part was set to 0.8 m ^3, and the volume ratio of the filter bed part to the biological treatment tank was set to 75%. Furthermore, the biological treatment tank 2h was set to have an effective capacity of 0.23 m ³ , the filter bed part was set to 0.19 m ^3, and the volume ratio of the filter bed part to the biological treatment tank was set to 82%. In addition, the tank from the biological treatment tanks 2a to 2h is the main reaction tank in the entire equipment.

  In these biological treatment tanks 2a to 2h, as described in the embodiment of FIG. 1 and FIG. 2, the fixed filter bed 4 is provided inside, and in this embodiment, in all the biological treatment tanks 2a to 2h. The filling rate of the filter medium 8 is 70% or more. The water layer portion in the upper part of the fixed filter bed 4 is set to 10 to 30 cm. The lower part of the fixed filter bed 4 is also an aqueous layer portion, and the upper and lower aqueous layer portions are configured to circulate water as shown in the direction of the arrow in FIG. Mild aeration is performed by the air diffuser tube 9 so that oxygen is present in the water layer, and sludge is accumulated in the fixed filter bed 4 and sufficient anaerobic conditions are set.

The effective capacity of the separation tank 3 is set to 0.5 m ³ . The effective capacity of the separation tank 3 is smaller than that of the biological treatment tanks 2a to 2h and the aerobic aeration tank 1, but since the sludge concentration is reduced in each of the biological treatment tanks 2a to 2h, this size is sufficient. It has become. As the sludge is reduced, the amount of separated sludge is small, and in this embodiment, the sludge is intermittently returned from the separation tank 3 to the aerobic aeration tank 1.

  As the filter medium 8, a skeleton spherical filter medium as shown in FIG. 3 was used. In the biological treatment tank 2a, a filter medium having a diameter of 15 cm is used. In the five biological treatment tanks 2b to 2f, a filter medium having a diameter of 12.5 cm is used. In the biological treatment tanks 2g and 2h, the filter medium is used. The diameter of 10 cm was used.

In the treatment facility of the present example, wastewater treatment was performed using chemical factory wastewater with a high acetic acid content as raw water. The amount and quality of raw water are as follows.
Raw water volume 10m ³ / day Raw water quality BOD (1200mg / l)
COD (600mg / l)
SS (100 mg / l)
n-hexane soluble content (100 mg / l)

Therefore, the volume load divided by the entire processing equipment is 0.86 kg BOD / m ³ · day, and the volume load of the fixed filter bed tank is 1.3 kg BOD / m ³ · day. Nitrogen and phosphorus were periodically replenished (BOD: N: P = 100: 5: 0.5). The DO value of the aerobic aeration tank 1 was 2 to 4 mg / l, and the biological treatment tanks 2 a to 2 h were water layer portions of 0.5 to 2 mg / l. In the measurement inside the filter medium of the biological treatment tank 2a and the biological treatment tank 2c, the ORP value was normally stable in an anaerobic region of −350 mV to −450 mV, and the sludge was blackened.

  The equipment of this example was stably operated, and no excess sludge was discharged after one year of operation. Initially, the sludge concentration in the aerobic aeration tank 1 which was 1000 mg / l was stabilized at 1000 to 1500 mg / l. When the facility air was temporarily stopped and the generated gas was captured and analyzed, methane was 50% and carbon dioxide was 20%.

  The inorganic carbonic acid content of the treated water (TC) is 80 mg / l on average, indicating that the carbonic acid content is discharged as inorganic carbon such as carbon dioxide. Therefore, it was found that the inflowing carbon as an organic substance (usually said to be about half of the BOD amount) was released as an inorganic substance in the atmosphere or during processing.

  The treated water quality is BOD 8 mg / l on average, COD 14 mg / l, SS 5 mg / l, n-hexane soluble 1 mg / l, maximum BOD 14 mg / l, COD 19 mg / l, SS 10 mg / l, n-hexane soluble 2 mg / l was obtained.

(Example 2)
In this example, the treatment facility of the above embodiment was used as an abatement facility for sewer drainage. The processing equipment of Example 1 was used as it was. Raw water, which is wastewater from food factories with high sugar and protein content, was treated as wastewater removal equipment. The target BOD was 200 mg / l or less, and processing was performed in a situation where the load was increased and the processing amount was increased.

The amount and quality of raw water are as follows.
Raw water volume 25m ³ / day Raw water quality BOD (1100mg / l)
COD (500mg / l)
SS (150mg / l)
n-hexane soluble content (70 mg / l)

Therefore, the volume load divided by the entire processing equipment is 2 kg / m ³ · day, and the volume load of the fixed filter bed tank is 2.6 kg / m ³ · day. Nitrogen and phosphorus were periodically replenished (BOD: N: P = 100: 4: 0.3). The DO value of the aerobic aeration tank 1 is 2.5 mg / l, the biological treatment tanks 2a to 2h are 0.5 to 1.0 mg / l in the water layer, and the inside of the filter medium of the biological treatment tank 2a and the biological treatment tank 2c is measured. Then, the ORP value was -350 mV to -500 mV, and the ORP value was often -50 mV or less even in the aqueous layer.

  The equipment of this example operated stably, and no excess sludge was discharged after one year of operation. The sludge concentration in the aerobic aeration tank 1 was 700 to 1000 mg / l. When the facility air was temporarily stopped and the generated gas was captured and analyzed, the methane was 64% and the carbon dioxide was 15%.

  The average carbonic acid content (TC) of the treated water was 150 mg / l. The treated water quality is average BOD 150 mg / l, COD 250 mg / l, SS 100 mg / l, n-hexane soluble content 10 mg / l, maximum value BOD 200 mg / l, COD 300 mg / l, SS 200 mg / l, n-hexane soluble content 15 mg / l was obtained.

(Example 3)
In this example, a raw water tank that was not provided in Examples 1 and 2 was provided. The volume of the raw water tank was 350 m ³ . Sludge was put in the aerobic aeration tank after the raw water tank and aerated to make BOD sludge. The capacity of this aerobic aeration tank was 350 m ³ . In this example, 18 biological treatment tanks were provided. The total capacity of the biological treatment tank was set to 580 m ³ . Furthermore, the capacity of the separation tank was 61 m ³ . A contact aeration tank was installed at the rear stage of the separation tank for finishing two tanks. The capacity of the two contact aeration tanks was set to a total of 50 m ³ . The total 18 biological treatment tanks have different sizes, but the ratio of the volume of the fixed filter bed in the biological treatment tank, that is, the filling rate of the filter medium is 70% or more.

Wastewater treatment was performed using food factory wastewater with the following protein-rich conditions as raw water.
Raw water volume 350m ³ / day Raw water quality BOD (1600mg / l)
COD (500mg / l)
SS (400mg / l)
n-hexane soluble component (150 mg / l)
Total nitrogen 80mg / l
Total phosphorus 4mg / l

Except for the raw water tank for storage, the volumetric load in the main processing equipment of the aerobic aeration tank, biological treatment tank, and separation tank is 0.6 kgBOD / m ³ · day, and the biological load in the biological treatment tank is 1.0 kgBOD / m ³・ It will be a day. The DO value of the aerobic aeration tank is 1.5 mg / l on the average, the biological treatment tank is 0.5 to 1.0 mg / l in the water layer, and the ORP value in the vicinity of the filter medium in the tank is -350 mV to- It was 500 mV.

  The equipment of this example operated stably, and there was no discharge of surplus sludge after one year of operation. The sludge concentration in the aerobic aeration tank was 1000 to 2000 mg / l. The treated water quality is BOD 8 mg / l, COD 15 mg / l, SS 10 mg / l, n-hexane soluble content 1 mg / l on average, BOD 15 mg / l, COD 20 mg / l, SS 20 mg / l, n-hexane acceptable 2 mg / l of solute was obtained. The total nitrogen and total phosphorus were 15.3 mg / l, respectively.

The schematic block diagram which shows the treatment facility of the organic wastewater as one Embodiment. The schematic perspective view of the biological treatment tank in the processing equipment of FIG. The perspective view of the filter medium used with the processing equipment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Aerobic aeration tank 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h ... Biological treatment tank 3 ... Separation tank

Claims (2)

An organic wastewater treatment facility equipped with at least two or more biological treatment tanks, wherein a fixed filter is attached to the biological treatment tank corresponding to a capacity equivalent to at least 1/2 or more of the total capacity of the at least two biological treatment tanks. A floor (4) is installed, and among the at least two or more biological treatment tanks, the foremost biological treatment tank is an aerobic aeration tank (1) not provided with a fixed filter bed (4), A biological treatment tank provided with a fixed filter bed (4) is provided on the rear stage side of the aerobic aeration tank (1), and the fixed filter bed (4) in the biological treatment tank in which the fixed filter bed (4) is installed. An air bubble blocking wall (5) is provided in the fixed filter bed (4) so that the air bubbles diffused in the water layer portion where no water is present do not directly hit the filter medium (8) in the fixed filter bed (4). is, the filter medium of the fixed filter bed (4) (8) has a specific surface area of the 60~100m ² / m ³ Such is formed as a skeleton-like spherical filter medium, a and the stationary filter bed (4) 70 to 90% by volume filling ratio of the filter medium (8) for the installation has been tank volume of the biological treatment tank, said fixed filter bed (4 ) And biological treatment tanks with no fixed filter bed installed are configured to have a capacity load of 0.6 kg BOD / m ³ · day to 2.5 kg BOD / m ³ · day. An organic wastewater treatment facility characterized by An organic wastewater treatment method for treating organic wastewater with an organic wastewater treatment facility having at least two or more biological treatment tanks, wherein the total capacity of the at least two or more biological treatment tanks is at least 1 / A fixed filter bed (4) is installed in a biological treatment tank equivalent to two or more capacities, and the biological treatment tank on the foremost stage among the at least two biological treatment tanks is provided with a fixed filter bed (4). A non-aerobic aeration tank (1), a biological treatment tank equipped with a fixed filter bed (4) on the rear side of the aerobic aeration tank (1), and a living organism in which the fixed filter bed (4) is installed The fixed filter bed (4) is diffused in an aqueous layer where no fixed filter bed (4) exists in the treatment tank, and the air bubbles do not directly hit the filter medium (8) in the fixed filter bed (4). 4) a bubble blocking wall (5) diffusing the provided filter medium (8) of the fixed filter bed (4), the ratio Area is formed as a skeleton-like spherical filter medium such that 60~100m ² / m ^3, and 70 to the filling rate of the filter medium (8) with respect to the stationary filter bed (4) is installed in the tank volume of the biological treatment tank In a state of 90% by volume, the capacity load on all the biological treatment tanks where the fixed filter bed (4) is installed and the biological treatment tanks where the fixed filter bed is not installed is 0.6 kg BOD / m ³ · day ~ An organic wastewater treatment method comprising treating organic wastewater so as to be 2.5 kgBOD / m ³ · day .

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