JP2004202320A - Method and apparatus for reducing volume of sludge and organic suspended substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively digest excess sludge formed in activated sludge treatment equipment or organic SS formed in a pressure floating separator or a flocculation/sedimentation tank without using an expensive apparatus to markedly reduce the quantity of excess sludge or organic SS formed in the pressure floating separator or the flocculation/sedimentation tank. <P>SOLUTION: The organic SS generates sludge with a solid concentration of 4,000-40,000 mg/l formed by an activated sludge method and/or organic SS with a solid concentration of 4,000-40,000 mg/l formed by a pressure floating separation method or a sedimentation/separation method for raw water is supplied to a digestion tank having a fixed bed therein and capable of performing aerobic digestion by the aeration of an aqueous phase part other than the fixed bed while keeping the fixed bed anaerobic. The sludge and/or organic SS is reduced in volume so that the solid concentration of 4,000-40,000 mg/l of the sludge and/or organic SS is reduced by half and the BOD value thereof becomes 3,000 mg/l or below. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for reducing the volume of sludge and other organic suspended substances (hereinafter also referred to as organic SS) in an activated sludge treatment facility, and more specifically, for example, a sewage treatment plant, a human waste treatment plant, and the like. Waste sludge generated in wastewater treatment equipment that treats wastewater discharged from wastewater treatment processes, food factories, manufacturing processes of the chemical industry, etc. with activated sludge, and pressurized flotation equipment and coagulation sedimentation equipment in separate processes in wastewater treatment The present invention relates to a method and an apparatus for reducing the volume of an organic suspended substance separated by the above method.
[0002]
Problems to be solved by the prior art and the invention
2. Description of the Related Art Activated sludge processes have been widely used for treating wastewater discharged from sewage treatment processes such as sewage treatment plants and human waste treatment plants, and manufacturing processes of food factories and chemical industries.
[0003]
This activated sludge method is performed by an activated sludge treatment facility equipped with an aeration tank and a sedimentation tank, but after decomposing organic substances and the like in wastewater by microorganisms in the sludge, surplus sludge that has been used, that is, Excess sludge will inevitably occur.
[0004]
Treatment and disposal of such excess sludge is costly and how to treat it is an important issue.
[0005]
Therefore, a treatment method for reducing excess sludge has also been developed, and a method that is often used at present is a method of digesting in a completely anaerobic atmosphere using a large anaerobic digestion tank.
However, this method requires an anaerobic digestion tank for sludge with great corrosion resistance, requires measures to generate methane and hydrogen sulfide, and requires a huge gas tank, resulting in huge costs. Was to be done.
Moreover, while investing such a huge amount of money, the sludge reduction rate was at most about 40 to 50%.
[0006]
On the other hand, as a method of disposing of sludge, a method of incinerating a large amount of dewatered sludge is mainly used, but there is a possibility that toxic gases such as dioxin may be generated, and environmental destruction may occur. Therefore, it is necessary to install an incinerator with good performance, oil for incineration is required, and the cost is increased. Further, even if a high-performance incinerator is installed, the possibility of generation of dioxin or the like cannot be eliminated.
[0007]
Therefore, methods other than the method using a large tank and the method of incineration as described above have recently been studied, and as a method of reducing excess sludge which has been partially put into practical use, for example, as described in Patent Document 1 below, A method for reducing sludge using microorganisms such as thermophilic bacteria, a method for reducing sludge using ozone as in Patent Documents 2 and 3, and a method for reducing weight using chemicals as in Patent Document 4 below, There is a method of crushing sludge using a mill as in Patent Document 5.
[0008]
[Patent Document 1]
JP-A-11-90493
[Patent Document 2]
Patent No.2973761
[Patent Document 3]
JP-A-7-116685
[Patent Document 4]
Japanese Patent No. 2132622
[Patent Document 5]
German Patent Application No. 4030668
[0009]
These methods mainly decompose excess sludge using microorganisms, ozone, chemicals, mills, and the like. However, since the decomposed excess sludge becomes new BOD, it must be renewed for the BOD decomposition. Activated sludge treatment equipment requires a complicated process, and activated sludge treatment equipment also needs to be expanded or aerated to treat the increased BOD amount. In addition, not only the operating cost but also the operating cost of the activated sludge treatment equipment itself is required to be higher, which increases the cost.
[0010]
Furthermore, as a device for removing organic SS separately from pretreatment of activated sludge equipment and activated sludge, techniques such as pressure flotation equipment, pressureless flotation separation, and coagulation sedimentation are used. In the past, organic fossils and discharged sludge that had become highly concentrated due to the organic SS discharged from the equipment were dehydrated and incinerated or treated as compost materials or industrial waste at treatment plants and factories without a proper method to treat them. There was no other way but to discharge it outside.
[0011]
In order to solve all of the above problems, the present invention uses a high-cost device to remove excess sludge generated in activated sludge treatment equipment and organic SS generated in a pressurized flotation device or a coagulation settling tank. An object of the present invention is to reduce the amount of excess sludge and organic SS generated in activated sludge treatment equipment and pressurized flotation separators by inexpensive digestion.
[0012]
[Means for Solving the Problems]
The present invention has been made as a method and an apparatus for reducing the volume of sludge and organic suspended substances in order to solve such problems, and features as a method for reducing the volume of sludge and organic suspended substances. Is the sludge generated by the activated sludge method and / or the organic suspended matter generated by the pressurized flotation method or the sedimentation method of the raw water, and the concentration is 4000 to 40,000 mg / l. A sludge and / or organic suspension is supplied to a digestion tank equipped with a fixed bed and capable of performing aerobic digestion by aerating an aqueous phase portion other than the fixed bed while keeping the fixed bed portion anaerobic. The sludge and / or organic suspension is controlled so that the solid concentration of the substance is less than half the concentration of the sludge and / or organic suspension substance of 4000 to 40,000 mg / l and the BOD value is 3000 mg / l or less. It is to reduce the volume of the substance.
[0013]
Another feature of the method for reducing the volume of sludge and organic suspended substances is sludge generated by the activated sludge method and / or organic suspension generated by the pressurized flotation method or sedimentation method of raw water. Suspended substances having a concentration of 4000 to 40,000 mg / l are supplied to a digestion tank of the preceding stage provided with an air inflow agitating means on the upper part which is at least 1/3 of the dimension in the depth direction. In the above, the air inflow stirring means aerobically treats the sludge and the organic suspended matter in the upper part while stirring the sludge, and the sludge and the organic matter in the lower part without applying the stirring force of the diffuser stirring means. The suspension is subjected to anaerobic treatment in a state where it is allowed to stand still, and the sludge and the organic suspension are digested so that the sludge to be treated aerobically and the sludge to be treated anaerobically do not mix. The sludge and organic suspended solids digested in the digestion tank at the previous stage are equipped with a fixed bed inside. The aerobic digestion can be performed by aerating the aqueous phase other than the fixed bed while keeping the fixed bed anaerobic, while supplying the sludge and / or organic suspended matter to the digestion tank. The sludge and / or the organic suspended substance is so controlled that the solid concentration is not more than half of the concentration of the sludge and / or the organic suspended substance having the 4000 to 40,000 mg / l and the BOD value is not more than 3000 mg / l. It is to reduce the volume.
[0014]
Further, as a feature of the apparatus for reducing the volume of sludge and organic suspended substances, an air inflow stirring means is provided at an upper portion of a tank main body having a dimension equal to or more than 1/3 of a depth direction, and the air inflow stirring means is used. In the upper part of the main body, sludge and organic suspended matter are aerobically treated while stirring, and in the lower part of the tank main body, sludge and organic suspended matter are not acted on by the agitating force of the diffuser stirring means. An anaerobic treatment is performed in a state where the sludge is left standing, and a digestion tank at a former stage configured so that the sludge to be aerobically treated and the sludge to be anaerobically treated are not mixed, and a fixed bed therein. In addition, a digestion tank at a later stage configured to perform aerobic digestion by aerating an aqueous phase portion other than the fixed bed while keeping the fixed bed portion anaerobic.
[0015]
The concentration of sludge and / or organic SS is 4000 to 40,000 mg / l. If the concentration is less than 4000 mg / l, the treatment cost may increase, while if the concentration exceeds 40,000 mg / l, there is a possibility that problems of treatment efficiency and odor are likely to occur. From this viewpoint, the sludge concentration is more preferably 10,000 to 20,000 mg / l.
If sludge is continuously added, the rate of anaerobic digestion may decrease. Therefore, it is desirable to add sludge to the sludge digestion tank intermittently.
[0016]
In order to increase the processing capacity of the apparatus of the present invention, it is better to raise the temperature in the digestion tank.If the temperature is below 15 ° C., the processing capacity may decrease, and the capacity of the apparatus increases, which is economically problematic. , 15 ° C. or higher. In this respect, the temperature is more preferably equal to or higher than 25 ° C.
There is no problem with the upper limit of the temperature if it is the limit of anaerobic digestion, but if it is too high, a considerable amount of heat retention energy is required, the odor of sludge becomes a problem, and the device itself needs special specifications that can withstand high temperatures. Become. Therefore, from this viewpoint, the temperature is preferably 60 ° C or lower, and more preferably 50 ° C or lower from various economical viewpoints.
[0017]
In the present invention, it is more efficient to circulate the aqueous phase of the digestion tank as much as possible in the flowing state, but from this viewpoint, the treated water is returned from the latter digestion tank to the former digestion tank. It is preferable to provide a circulation line that can circulate the treated water.
[0018]
In the volume reduction device as described above, using a digestion tank provided with a fixed bed having a large number of holding materials, submerging the fixed bed in water containing sludge and high-concentration organic suspended substances, The mixture is stirred by aeration so that air is not mixed into the water, and flowing water containing no air bubbles is passed through a fixed bed for treatment.
[0019]
In this manner, anaerobic digestion is performed by strengthening the anaerobic conditions in the fixed bed portion, and the sludge is oxidized by aeration and agitation in the aqueous phase portion other than the fixed bed, whereby excess sludge and / or high-concentration organic SS is removed. Perform digestion.
[0020]
In the fixed bed, it is necessary to increase the density of the fixed bed so that the sludge accumulates thereon and a sufficient anaerobic condition is obtained, for example, so that the oxidation-reduction potential is -300 mv or less. To prevent this, the structure and density of the fixed bed must be determined so that the accumulated sludge can be sufficiently separated and cleaned by merely increasing the aeration strength outside the bubble intrusion prevention wall. As a structure of the carrier provided in the fixed bed, a packing carrier for gas-liquid contact, such as a teralet-shaped, saddle-shaped, short tube-shaped material, or the like can be used.
[0021]
In the apparatus of the present invention, the number of tanks (the number of stages) does not matter, and one or two tanks may be used. However, increasing the number of tanks has the effect of lowering the BOD value and SS value of treated water. However, on the other hand, the entire processing apparatus tends to be relatively large.
[0022]
It is also possible to install a hot water pipe, a steam pipe, a heated air pipe, an electric heater or the like as a heat retaining device.
[0023]
In the above digestion tank, the level of the lower sludge zone is determined and drain pipes are installed.The sludge that rises to a higher level and accumulates in the sludge zone is guided to the digester in the latter stage, and if it is processed, the latter Before entering the digestion tank, the bacteria of anaerobic digestion will be introduced, and the anaerobic digestion will be easily performed, and even in the preceding digestion tank, the control of the sludge zone will be easier, leading to an increase in the capacity of each. So it will be a more economical way.
In addition, when the water in the upper aqueous phase of the first digestion tank is circulated and flowed into the second digestion tank, the treatment efficiency is improved, and the quality of the treated water is also improved.
[0024]
The water depth of the digestion tank is preferably about 1 to 8 m, more preferably 2 to 5 m. The height of the sludge digester is set accordingly. If the depth is less than 1 m, the efficiency is reduced because the part that maintains the anaerobic state is reduced, and if it is more than 8 m, a dead zone tends to be formed below, and the stirring flow becomes strong and the space of the aerobic treatment section becomes large. This is because the treated water is likely to be deteriorated and deteriorated.
[0025]
The size of the equipment varies considerably depending on the type and temperature of the excess sludge and organic SS to be treated, the required quality of the treated water, and the set temperature of the equipment, but the sludge concentration is 15000 mg / l and the flow rate is 5 m. ^Three / day, 50 ~ 100m at 40 ℃ ^Three Can be processed by a device having an effective capacity of
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of an apparatus for reducing the volume of sludge and organic SS according to one embodiment. The digestion tank 1 of the volume reduction device according to the present embodiment is divided into two compartments 3 and 3 via a partition wall 2 as shown in FIG.
[0028]
In the compartment 3, fixed floors 4 and 4 are provided at two places on the left and right, respectively. The fixed floor portion 4 is provided with an inner wall 5 for preventing air bubble intrusion on a side surface thereof, and wire nets 6, 7 provided on upper and lower portions thereof. The fixed floor portion 4 is filled with a large number of sludge holding materials 8.
[0029]
In addition, diffuser pipes 9, 9 are provided substantially at the centers of the compartments 3, 3, respectively. The position of the air diffuser 9a provided at the lower end of the air diffuser tube 9 is set so as not to fall below the lower end of the air bubble intrusion prevention inner wall 5.
[0030]
Further, on the bottom side of the digestion tank 1, a heat retaining pipe 10 is provided. The heat retaining pipe 10 is provided so as to penetrate one compartment 3 and enter the other compartment 3.
[0031]
An inflow pipe 11 is provided in one compartment 3, and a transfer pipe 12 for transferring treated water in the one compartment 3 to the other compartment 3 is provided near the partition wall 2. I have. Further, the other compartment 3 is provided with a discharge pipe 13 for discharging the treated water in the other compartment 3 to the outside.
[0032]
Next, a method of digesting sludge and organic suspended matter by such a device will be described.
[0033]
First, raw water flows into the digestion tank 1 via the inflow pipe 11. Raw water is generated in sludge discharged from activated sludge treatment equipment and in pressurized flotation equipment.
Organic SS and the like are contained.
[0034]
The flowed raw water is further flowed into the other compartment 3 via the transfer pipe 12. Since the air diffusers 9 are provided substantially at the centers of the respective compartments 3 and 3, air is introduced from the air diffuser 9a of the air diffusers 9 and 9 so that the compartments 3 are provided. The so-called aeration agitation is performed in the aqueous phase portion other than the fixed bed portion 4 inside.
[0035]
In this case, since the inner wall 5 for preventing air bubble intrusion is provided on the side surface of the fixed floor portion 4, air bubbles are prevented from entering the fixed floor portion 4 from the side surface side, and the lower end of the air diffuser 9 is also provided. The position of the air diffuser 9a is set so that it does not fall below the lower end of the bubble intrusion prevention inner wall 5, so that the air bubbles released from the air diffuser 9a are not intruded. Is prevented from entering the fixed floor 4 from the wire mesh 7 below.
[0036]
Therefore, in the present embodiment, aeration is performed in the aqueous phase portion in the compartment 3 other than the fixed bed portion 4, so that aerobic treatment is performed, and the intrusion of air into the fixed bed portion 4 is as described above. Therefore, an anaerobic treatment is performed in the fixed floor portion 4.
[0037]
The treated water treated in the latter compartment 3 is discharged to the outside from the drain pipe and discharged. However, it is also possible to return to the preceding compartment 3 and circulate without discharging to the outside.
[0038]
(Embodiment 2)
In the present embodiment, an apparatus is used in which a digestion tank 15 having the same structure as that of the above-described first embodiment is provided at the subsequent stage, and another digestion tank 14 is provided at the preceding stage.
The digestion tank 14 at the former stage has an aerobic treatment section 17 for aerobically treating sludge and an anaerobic treatment section 18 for anaerobically treating sludge in a tank body 16.
[0039]
The aerobic processing section 17 and the anaerobic processing section 18 are not necessarily partitioned in the tank body 16, but the aerobic processing section 17 is agitated to diffuse the sludge. Aerobic treatment is performed, and the anaerobic treatment part 18 is treated anaerobically by leaving the sludge standing without stirring, so the aerobic treatment part 17 and the anaerobic treatment part 18 are conceptual only. It is formed in. Therefore, the position of the boundary between the aerobic processing unit 17 and the anaerobic processing unit 18 may be specified, or may not be clearly specified. On the upper part of the tank main body 16, a gas diffuser 19 is provided.
[0040]
Then, when air is introduced from the diffused gas 19, diffused stirring is performed in the aerobic processing unit 17. On the other hand, the stirring effect of the air flowing from the diffused gas 19 is adjusted such that the inflow amount of the air does not reach the part of the anaerobic processing unit 18, and as a result, in the anaerobic processing unit 18, The sludge is left standing.
[0041]
As a result, while the entire inside of the tank main body 16 is a tank having one continuous space, the aerobic processing unit 17 separately performs aerobic processing and the anaerobic processing unit 18 separately performs anaerobic processing. It is done.
[0042]
Further, the digestion tank 15 in the latter stage is provided with an inner wall 5 for preventing air bubble intrusion on the side surface and wire meshes 6 and 7 on the upper and lower sides, similarly to the apparatus of the first embodiment, so that many sludge holding materials are provided. Reference numeral 8 denotes a fixed floor portion 4 filled on the left and right sides.
[0043]
However, the digestion tank 15 in the latter stage does not have two compartments as in the apparatus of the first embodiment, and is composed of only one compartment. The point that the air diffuser 9 is provided substantially in the center and the point that the heat retaining pipe 10 is provided on the bottom side of the tank body 20 are the same as in the first embodiment.
[0044]
The upstream digestion tank 14 is provided with an inflow pipe 21, and the upstream digestion tank 14 and the downstream digestion tank 15 are provided with an aqueous phase transfer pipe 22 and a sludge transfer pipe 23. The aqueous phase transfer pipe 22 and the sludge transfer pipe 23 become outflow pipes in the digestion tank 14 in the former stage, and become inflow pipes in the digestion tank 15 in the latter stage.
[0045]
Next, a method of digesting sludge and organic suspended matter by such a device will be described.
[0046]
First, the sludge discharged from the activated sludge treatment facility and the raw water containing the organic suspended matter generated by the pressurized flotation device or the like are caused to flow into the digestion tank 14 in the former stage. The raw water that has flowed into the digestion tank 14 on the front side is further flowed into the digestion tank 15 on the rear side via the aqueous phase transfer pipe 22 and the sludge transfer pipe 23.
[0047]
In the digestion tank 14 at the former stage, air is introduced from the diffused gas 19, thereby performing diffused stirring in the aerobic treatment unit 17. In this case, the effect of stirring the air flowing in from the diffused gas 19 does not reach the anaerobic treatment section 18. Accordingly, no agitation is performed in the anaerobic treatment section 18, and the sludge remains in a stationary state.
[0048]
As a result, while the entire inside of the tank main body 16 is a tank having one continuous space, the aerobic processing unit 17 separately performs aerobic processing and the anaerobic processing unit 18 separately performs anaerobic processing. It is done.
[0049]
The sludge and the organic suspended matter that have not been consumed in the digestion tank 14 in the first stage are supplied to the digestion tank 15 in the second stage through the sludge transfer pipe 23. Further, the treated water treated in the digestion tank 14 in the first stage is supplied to the digestion tank 15 in the second stage through the aqueous phase transfer pipe 22.
[0050]
Since the air diffuser 9 is provided substantially at the center of the digestion tank 15 on the subsequent stage, the treated water supplied to the digestion tank 15 is supplied with air from the air diffuser 9a of the air diffuser 9 as in the first embodiment. The aeration is performed in the aqueous phase portion by the inflow.
[0051]
Further, since the position of the air diffuser 9a provided at the lower end of the air diffuser 9 is set so as not to be lower than the lower end of the air bubble intrusion prevention inner wall 5, the air bubbles released from the air diffuser 9a are set. Does not penetrate into the fixed floor 4 from the lower wire mesh 7, and the fixed floor 4 is provided with an inner wall 5 for preventing air bubbles from entering the side of the fixed floor 4. Air bubbles are also prevented from entering the air.
[0052]
Therefore, also in this embodiment, aeration is performed in the water phase portion other than the fixed bed portion 4 to perform aerobic treatment, and the intrusion of air into the fixed bed portion 4 is prevented as described above. In the fixed floor 4, an anaerobic process is performed.
[0053]
The treated water treated in the digestion tank 15 on the downstream side is discharged to the outside from the drainage pipe 13, but a part of the water is returned to the digestion tank 14 on the upstream side by the return pipe 24, and It will circulate with the digestion tank 15 on the subsequent stage.
[0054]
As described above, in the present embodiment, in the former digester 14, the excess sludge and the water containing the high-concentration organic suspended matter are subjected to anaerobic and aerobic digestion to reduce the amount of sludge. The sludge interface rises above a certain level, flows into the digestion tank 15 at the subsequent stage by the sludge transfer pipe 23, and is further digested. Therefore, the volume of the sludge and the organic suspended matter can be reduced more favorably. Further, the water in the upper aqueous phase of the digestion tank 14 in the former stage is transferred to the digester 15 in the latter stage through the aqueous phase transfer pipe 22 and circulated, so that the treatment efficiency is further improved and the quality of the treated water is improved. Is better.
[0055]
(Embodiment 3)
In the present embodiment, a digestion tank 14 having the same structure as that of the above-described second embodiment is provided at the front stage, and the digestion tank 14 of the second embodiment has the same structure as the digestion tank 15 of the second embodiment, but is divided into a plurality of compartments. A device provided at the subsequent stage of 15 is used.
[0056]
The digestion tank 14 at the former stage includes an aerobic processing unit 17 and an anaerobic processing unit 18 as in the second embodiment. Further, the point that a gas diffuser 19 is provided on the upper part of the tank body 16 is also the same as in the first embodiment. Further, the digestion tank 15 at the latter stage is divided into two digestion compartments 3a, 3a, a separation compartment 3b, and a sterilization compartment 3c.
[0057]
The two digestion compartments 3a, 3a have exactly the same configuration as the compartment 3 of the first embodiment and the digestion tank 15 of the second embodiment. The separation compartment 3b basically has the same configuration as the digestion compartments 3a, 3a, but differs from the digestion compartment 3a in that a tapered surface 25 is formed at the lower right side. Sludge floating in the separation compartment 3b is collected near the bottom of the separation compartment 3b along the tapered surface 25, and a suction port (not shown) of a sludge return pipe (not shown) near the bottom is provided. Is returned to the digestion tank 14.
[0058]
The treated water that has been treated and separated in the separation compartment 3b is transferred from the transfer pipe 12 to the sterilization compartment 3c, but a part of it is returned to the digestion tank 14 in the preceding stage by the return pipe 24, and the digestion in the preceding stage is performed. The tank 14 and the digestion tank 15 at the subsequent stage are circulated.
[0059]
Further, in the sterilization compartment 3c, a sterilization process is performed, and in that state, the water is discharged from the discharge pipe 13 to the outside.
[0060]
The point that the water in the upper aqueous phase of the digestion tank 14 on the front side is transferred to the digestion tank 15 on the subsequent side via the aqueous phase transfer pipe 22 is the same as in the second embodiment. The effect that the treated water is transferred from one digestion compartment 3a to the other digestion compartment 3a via the other, and the treated water is further transferred from the other digestion compartment 3a to the separation compartment 3b,
This is the same as in the first embodiment.
[0061]
In the present embodiment, the digestion tank 15 at the latter stage is divided into a total of four compartments of digestion compartments 3a, 3a, a separation compartment 3b, and a sterilization compartment 3c, and sterilization is performed in the sterilization compartment 3c at the final stage. Since the water is discharged after being made, the quality of the treated water is further improved.
[0062]
(Other embodiments)
In the first embodiment, the air diffuser 9 is provided as the air inflow stirring means. In the second and third embodiments, the gas diffuser 19 is provided in the digestion tank 14 in addition to the air diffuser 9. Means can also be employed.
[0063]
Further, in the above embodiment, the heat retaining pipe 10 is provided below the compartment 3 or the digestion tank 15, but it may be provided above.
[0064]
Further, the number of digestion tanks is not limited to the above-described embodiment, and the number of compartments is not limited even when the digestion tank is partitioned.
[0065]
【Example】
Hereinafter, examples of the present invention will be described.
[0066]
(Example 1)
BOD value is 100mg / l on average and 500m inflow ^Three 1m / day at activated sludge treatment facility ^Three , And excess sludge with a sludge concentration of 15000 mg / l is discharged.
Effective volume of 15m to reduce sludge volume ^Three A digestion tank as shown in Fig. 1 was installed, and the DO value of the water layer was 1.5 mg / l by aeration and the ORP value around the fixed bed was -350 mv. Processed. As a carrier provided on the fixed bed in the digester, a teralet type carrier was used.
[0067]
5m as circulating water ^Three / day was returned from the outlet to the inlet, and the evaporated water was replenished with tap water. Since treated water having an SS concentration of 500 mg / l and a BOD value of around 400 mg / l was obtained, the treated water was introduced into a raw water inflow line and introduced into an activated sludge treatment facility.
1m of treated water ^Three Since it is / day, it is 1/500 of the amount of raw water, and no change in the BOD value or SS of the raw water was observed even when mixed with the treated water.
This situation has been maintained for more than six months and no excess sludge has been discharged.
[0068]
(Example 2)
In the above equipment, 0.2m discharged from the pressure flotation device ^Three , 30,000 mg / l of starchy organic SS (floss) was treated with the excess sludge.
The processing temperature was set to 50 ° C. because the processing efficiency decreased and putrefactions accumulated inside. Since treated water having an SS concentration of treated water of 1000 mg / l and a BOD value of 800 mg / l was obtained, the treated water was returned to the raw water inflow line in the same manner as in Example 1 above.
[0069]
Treated water from the activated sludge treatment equipment of the main unit is stable with SS value of 15 mg / l or less and BOD value of 10 mg / l or less, and no more than half a year, neither excess sludge nor floss from pressure flotation has been discharged outside the system. .
When the treatment temperature in the digestion tank of this example was increased to 55 ° C., there was a slight odor, and the SS value of the treated water tended to increase, but the treatment could be performed.
[0070]
(Example 3)
BOD is 800mg / l and capacity is 300m ^Three Activated sludge treatment equipment that treats raw water after coagulation and sedimentation. Organic SS discharged from coagulation and sedimentation (0.5 m at a concentration of 35000 mg / l) ^Three / day) and surplus sludge discharged from activated sludge (4.8m at a concentration of 15000mg / l) ^Three / day), a digester as shown in FIG. 2 was used.
[0071]
In this volume reduction device, the first digestion tank has an effective capacity of 80 m ^Three , The depth of the water is 4.5m, the digestion tank at the latter stage is equipped with a fixed bed filled with Terralet type polypropylene carrier, the effective capacity is 80m ^Three The water was circulated using the digestion tanks at the first and second stages at a depth of 4.5 m. In the charging method, the surplus sludge and the organic SS discharged from the flocculation settling tank were withdrawn every two days, and charged every two days into the preceding stage of the digestion tank.
[0072]
Since the water temperature was 30 ° C., the treatment was performed for 10 months without increasing the temperature.
The SS of the treated water returning to the raw water from the digestion tank can be stably treated at 150 mg / l and the BOD value is 60 mg / l, and there is no problem at all in the activated sludge treatment equipment that treats the raw water into which the treated water flows. Did not.
[0073]
【The invention's effect】
As described above, the present invention is a sludge generated by the activated sludge method, and / or an organic suspended substance generated by the pressurized flotation method, the sedimentation method, or the like of raw water, and has a concentration of 4000 to 40,000 mg / The sludge is supplied to a digestion tank capable of performing aerobic digestion by aerating an aqueous phase other than the fixed bed while keeping the fixed bed part anaerobic while having a fixed bed inside. And / or the sludge so that the solid content of the organic suspended substance is not more than half of the concentration of the aforementioned 4000 to 40,000 mg / l and / or the concentration of the organic suspended substance and the BOD value is not more than 3000 mg / l. And / or a method for reducing the volume of organic suspended substances. Since the treated water can be returned to the activated sludge treatment facility and reprocessed without a large burden, the excess sludge of the activated sludge can be reduced and reduced. As a result, the amount of industrial waste can be significantly reduced compared to the past. There is an effect that it can be reduced.
[0074]
In addition, it is necessary to reduce the volume of high-concentration organic SS discharged from a pressurized separation flotation device or a coagulation sedimentation tank for separating organic SS in combination with activated sludge treatment equipment in wastewater treatment. Can be.
[0075]
Furthermore, since sludge and the like are hardly discharged, a dehydrator and a coagulating dewatering agent are not required, and there is no need to arrange personnel for dehydrating excess sludge, which has the effect of reducing the number of workers as a whole.
[0076]
Further, there is an advantage that the manufacturing cost and the operating cost of the apparatus are very low, and the apparatus can be automated and the operation management can be substantially reduced.
[0077]
Further, since the digested sludge obtained by the present invention is very easily dehydrated, it can be easily and inexpensively dewatered even when dewatered in some cases.
[0078]
Furthermore, the sludge generated by the activated sludge method and / or the organic suspended matter generated by the pressurized flotation method or the sedimentation method of the raw water, having a concentration of 4000 to 40,000 mg / l, The gas is supplied to the digestion tank at the preceding stage provided with an air inflow stirring means at the upper part which is equal to or more than one third of the dimension in the direction. While aerobically performing the treatment while stirring, the lower part performs the anaerobic treatment in a state where the sludge and the organic suspended substance are allowed to stand still without applying the stirring force by the diffuser stirring means, The sludge to be treated aerobically and the sludge to be treated anaerobically are digested so that the sludge and the organic suspended matter are not mixed, and then the sludge digested in the digestion tank at the preceding stage and the organic suspended matter are removed. With a fixed floor inside, keeping the fixed floor anaerobic The sludge and / or organic sludge and / or organic suspended solid having a solid concentration of 4000 to 40,000 mg / l is supplied to a subsequent digestion tank capable of performing aerobic digestion by aerating the portion. When reducing the volume of sludge and / or organic suspended matter so that the BOD value is less than or equal to 3000 mg / l at a concentration of less than half of the concentration of the aqueous suspended matter, Thereby, there is an effect that the volume of the sludge and the organic SS can be more favorably reduced.
[0079]
Further, when a circulation line is provided for returning the treated water from the latter digester to the former digester and circulating the treated water, the water phase of the digester is in a flowing state, so that the treatment efficiency is improved. There is an effect that is improved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an apparatus for reducing the volume of sludge and organic suspended matter as one embodiment.
FIG. 2 is a schematic sectional view of an apparatus for reducing the volume of sludge and organic suspended substances according to another embodiment.
FIG. 3 is a schematic sectional view of an apparatus for reducing the volume of sludge and organic suspended matter according to another embodiment.
[Explanation of symbols]
1 ... digestion tank 14 ... digestion tank
15… digestion tank

Claims (6)

Sludge generated by the activated sludge method and / or organic suspended solids generated by the pressurized flotation method, sedimentation method, etc. of raw water with a concentration of 4,000 to 40,000 mg / l are fixed-bed inside. To supply a digestion tank capable of performing aerobic digestion by aerating an aqueous phase portion other than the fixed bed while keeping the fixed bed portion anaerobic, and supplying sludge and / or organic suspended substances. The sludge and / or the organic suspended substance is so controlled that the solid concentration is not more than half of the concentration of the sludge and / or the organic suspended substance having the 4000 to 40,000 mg / l and the BOD value is not more than 3000 mg / l. A method for reducing the volume of sludge and organic suspended substances, which comprises reducing the volume. The method for reducing the volume of sludge and organic suspended matter according to claim 1, wherein the temperature of sludge and organic suspended matter in the digestion tank is maintained at 15 ° C to 60 ° C. The method for reducing the volume of sludge and organic suspended matter according to claim 1, wherein the temperature of sludge and organic suspended matter in the digester is maintained at 25C to 50C. The sludge generated by the activated sludge method and / or the organic suspended matter generated by the pressurized flotation method or the sedimentation method of the raw water with a concentration of 4000 to 40,000 mg / l The gas is supplied to the digestion tank (14) at the preceding stage provided with an air inflow stirring means on the upper part which is at least one third of the size. The suspension is aerobically treated while stirring, and the lower portion is anaerobically anaerobically kept sludge and organic suspension without standing by the agitating force of the diffuser stirring means. Process, digesting the sludge and organic suspended matter so that the aerobicly treated sludge and the anaerobically treated sludge are not mixed, and then the sludge digested in the digestion tank (14) in the preceding stage. In addition, a fixed bed is provided inside, and the organic suspended matter is kept anaerobic in the fixed bed, A sludge having a solid concentration of the sludge and / or the organic suspended matter of 4000 to 40,000 mg / l is supplied to a digestion tank (15) at a later stage capable of performing aerobic digestion by aerating the portion. Sludge and / or organic suspension, characterized in that the volume of sludge and / or organic suspension is reduced so that the BOD value is less than or equal to 3000 mg / l at half the concentration of the organic suspension or less. How to reduce the volume of a substance. An air inflow stirrer is provided at the upper part of the tank body (16) which is 1/3 or more of the dimension in the depth direction, and the air inflow stirrer stirs sludge and organic suspended matter at the upper part of the tank body (16). Aerobically while the sludge and the organic suspended matter are allowed to stand still at the lower part of the tank body (16) without exerting the stirring force of the diffuser stirring means. The digestion tank (14) of the former stage, which is configured so that the sludge to be aerobically treated and the sludge to be anaerobically treated are not mixed, and has a fixed bed inside, and a fixed bed portion is provided. Sludge, organic characterized by comprising a digestion tank (15) of the subsequent stage configured to be able to perform aerobic digestion by aerating an aqueous phase portion other than the fixed bed while maintaining anaerobic Device for reducing the volume of a suspended substance. 6. The sludge and organic suspended matter volume reduction according to claim 5, wherein a circulation line is provided for returning the treated water from the latter digester (15) to the former digester (14) and circulating the treated water. apparatus.

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