JP2002263672A - Method and facility for treating high concentration organic waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high concentration organic waste water treatment system which requires only a small floor space, small cost of operation and equipment, etc., and which brings about performance equivalent or superior to that of a conventional two-step activated sludge treatment approach by an easy driving operation. SOLUTION: A high concentration organic waste water treatment method is provided with a combination of: a 1st stage for treating high concentration organic waste water by the fluidized bed biological treatment method; and a 2nd stage for directly treating 1st process effluent by the activated sludge treatment method, carrying out the solid-liquid separation of the treated water and separating the sludge. It is preferable to stabilize the treatment by dividing the water treatment tank of the fluidized bed biological treatment method to a plurality of tanks and to make the load of the later stage tanks lower than that of the preceding stage, or to set the BOD load in each tank nearly identical by dividing the water treatment tank of the fluidized bed biological treatment method into a plurality of tanks and increasingly reducing the size of the tanks of the later stages by a fixed ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating high-concentration organic wastewater, and by combining a fluidized-bed type biological treatment method and an activated sludge method, a reduction in treatment space and energy saving, and a high efficiency. It relates to a processing method that can be processed.

[0002]

2. Description of the Related Art Activated sludge treatment is widely used as a biological treatment method for organic wastewater. Particularly, as a method for treating high-concentration organic wastewater, the first stage is set to a high load. A two-stage activated sludge treatment method (adsorption-activated sludge method: AB method) for treatment is widely known. In this two-stage activated sludge treatment method, the load of the former stage is different from that of the latter stage. Furthermore, when the two-step activated sludge treatment method is described in detail,
The organic wastewater is oxidized and decomposed in the first stage by microbial treatment mainly of bacteria in the first stage,
This is a treatment method for improving biological treatment efficiency by converting the non-aggregating bacteria into non-aggregating bacteria in a second stage, and predating and removing the non-aggregating bacteria by microbial treatment mainly using protozoa. Thereby, high-load operation can be performed in the first stage, and the treatment efficiency by the activated sludge treatment method is improved, and at the same time, the amount of excess sludge generated can be reduced.

[0003] In recent years, attention has been paid to a treatment in which the first stage of the two-stage activated sludge treatment is a fluidized bed biological treatment method.
Specifically, wastewater is biologically treated first in a system in which a microbial carrier is suspended, and sludge is separated and separated in a first settling tank, and the primary treated water obtained there is converted into activated sludge in the second step. There is known a method of obtaining treated water by sending it to an aeration tank in which it is put and biologically treating the sludge, and sedimenting and separating sludge from effluent from the aeration tank in a second sedimentation tank.

Further, in this method, the sludge precipitated and separated in the second sedimentation tank is added to the effluent from the system in which the microorganism carrier is suspended, thereby promoting the sedimentation and separation of the sludge in the first sedimentation tank. Is to be performed. Although this method is highly efficient, it requires two stages each of a treatment tank and a sedimentation tank, and requires two sedimentation tanks requiring a relatively large surface area. It needs a size that is almost the same as

Further, in the two-stage activated sludge treatment method using the fluidized bed biological treatment method, the effluent of the fluidized bed aeration tank is subjected to anaerobic filtration in order to simultaneously remove nitrogen in addition to removing BOD and the like. Introduce into the anaerobic filter bed tank the sludge outflow from the fluidized bed aeration tank by introducing into the bed tank and then through the contact type aeration tank and the sedimentation tank in order to perform the anaerobic decomposition and digestion of the sludge. Along with proceeding, the sludge is captured by the filter medium filled in the anaerobic filter bed tank, and the outflow of the sludge is stopped. There has been proposed a method of denitrification by reducing wastewater obtained by nitrifying nitrogen or ammonia nitrogen in wastewater to nitrite or nitrate nitrogen in an anaerobic environment in the presence of organic substances in the presence of organic matter. However, this method has various drawbacks, such as the fact that the anaerobic filter tank is used as the anaerobic treatment tank, the tank is easily clogged, and bad odor is generated.

[0006]

In the above-described conventional two-stage activated sludge treatment method, the activated sludge treatment in each stage involves the following steps.
It was necessary to set up a sedimentation tank, return sludge, and pull out.
For this reason, there are problems that the processing plant becomes large, the construction cost becomes high, and the operation management becomes complicated.
In addition, the method of first performing the fluidized bed biological treatment method has various disadvantages such as a large floor area of the apparatus, or when an anaerobic filter tank is used, the tank is easily clogged, and the operation is difficult. This is as described above. The present invention
The present invention has been made in view of the above-mentioned problems of the conventional two-stage activated sludge treatment method.
The high load tank of the first stage of the activated activated sludge treatment method eliminates the burden of installing, returning and extracting sludge in the settling tank that was required between the first and second stages, reducing operating costs and equipment costs. It is an object of the present invention to provide a treatment system which is inexpensive and has a performance equal to or higher than that of a conventional two-stage activated sludge treatment method by a simple operation.

[0007]

According to the present invention, the above objects can be attained by the following means. (1) The first step in which high-concentration organic wastewater is treated by a fluidized-bed biological treatment method, and the effluent in the first step is directly treated by an activated sludge treatment method, and the treated water is separated into sludge by solid-liquid separation. A method for treating high-concentration organic wastewater, comprising combining the second step. (2) The process described in (1) above, wherein the treatment water tank of the fluidized bed biological treatment method, which is the first step, is divided into multiple tanks, and the load on the subsequent stage is set lower than that of the preceding stage to stabilize the treatment. Of high-concentration organic wastewater. (3) The treatment water tank of the fluidized bed biological treatment method, which is the first step, is divided into multiple tanks, and the separation method of each tank is reduced at a fixed ratio in the latter stage so that the BOD load in each tank is substantially the same. The method for treating high-concentration organic wastewater according to the above (1), wherein the treatment efficiency is improved by setting. (4) Combination of the first step consisting of a fluidized bed biological treatment tank and the second step consisting of an activated sludge treatment tank for introducing effluent from the fluidized biological treatment tank and a solid-liquid separator. A high-concentration organic wastewater treatment apparatus characterized by the following features.

In the system having the above-described structure, the operation of treating high-concentration organic wastewater is described. Organic matter in raw water supplied from a raw water introducing means to a fluidized-bed biological treatment tank (also referred to as a fluidized-bed contact tank) is as follows. Oxidative decomposition treatment is carried out by the biological oxidizing action of microorganisms attached to the surface of the flowable carrier placed in the treatment tank. Furthermore, the treated water treated in the fluidized-bed biological treatment tank is directly subjected to activated sludge treatment as a post-stage treatment, whereby the remaining organic substances are decomposed, and the SS of the aeration liquid has a uniform particle size. In the sedimentation basin, the sludge having excellent sedimentation property and the supernatant water having high clarity are separated to obtain good treated water quality. In addition,
The fluidized bed type biological treatment tank in the present invention refers to a state in which a large number of particulate carriers or the like carrying microorganisms are dispersed in an organic wastewater for biological treatment, and in a state of being fluidized in the wastewater, A large number of solid particles are dispersed and flowed in a rising airflow in a normal tower, and the function is different from that in which a fluidized bed of solid particles is formed below a certain interface. "

As described above, by directly treating the treated water in the fluidized biological treatment tank by the aeration method of the activated sludge treatment method, the water between the fluidized bed tank in the first step and the aeration tank in the second step is treated. Compared with the wastewater treatment method with the first settling tank and the wastewater treatment method with the anaerobic filter bed tank between the fluidized bed type aeration tank and the contact aeration tank, the processing space of the entire treatment process is significantly compact. And energy saving can be realized.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. Table 1 and FIG. 5 relate to a conventional two-stage activated sludge treatment method, and Tables 2 to 4 and FIGS. 1 to 4 show fluidized bed biological treatment according to embodiments of the present invention. 2 by the combination of the activated sludge treatment method
It relates to a step biological treatment method.

Hereinafter, a two-stage biological treatment method according to embodiments of the present invention will be described. In all the drawings for explaining the examples and comparative examples, those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.
FIG. 1 is a schematic configuration diagram of a processing apparatus used in Embodiment 1 of the present invention. In this treatment apparatus, a first step including a fluidized bed biological treatment tank (fluidized bed contact tank) 2 is connected to a second step including an aeration tank 6 and a sedimentation tank 8. In this treatment apparatus, wastewater treatment is performed by a suspension (fluid contact) treatment method in which a carrier 3 supporting microorganisms is suspended in a liquid in a first step, and wastewater treatment by an activated sludge method is performed in a second step. Will be In FIG. 1, raw water 1 enters a fluidized-bed biological treatment tank 2, and is biologically treated in a fluidized state by introducing a carrier 3 dispersed therein and air 4, and is treated with a high load. The activated sludge mixture 5 enters the aeration tank 6 of the second step and is subjected to aerobic biological treatment, and the activated sludge mixture 7 enters the sedimentation tank 8 where the sludge is settled, and the supernatant water is obtained as treated water 9. Most of the settled sludge is returned to the aeration tank 6 as returned sludge 10.

FIG. 2 is a schematic configuration diagram of a treatment apparatus used in Example 2 which combines a two-tank fluidized bed biological treatment and an activated sludge treatment. In FIG. 2, 2A is the first tank,
B is a second tank, which is connected in series so that the first tank effluent enters the second tank. FIG. 3 is a schematic configuration diagram of a treatment apparatus that combines a 4-tank fluidized bed biological treatment and an activated sludge treatment used in Example 3. In FIG. 3, 2A is the first
The tank 2B is a second tank, 2C is a third tank, 2D is a fourth tank, and is connected in series from the first tank to the fourth tank.

FIG. 4 is a schematic explanatory view showing a modified example of the four-tank fluidized-bed biological treatment tank 1 shown in FIG. In FIG.
The first tank 2A is divided into three tanks, and the second tank 2B is divided into two tanks.
The raw water under treatment is divided into two tanks, and the raw water being treated flows in parallel, and the third tank 2C and the fourth tank 2D are connected in series so as to flow in series. In the fluidized contact tank 2, the raw water 1 is separately supplied to each of the three tanks constituting the first tank 2A in FIG. 3, and the wastewater treatment by the suspension treatment method is performed in each tank in parallel. The treated water is then collected from each tank, and the treated water is collected in the second tank 2B.
Is supplied separately to each of the two tanks constituting the tank, and the treated water subjected to the wastewater treatment by the suspension treatment method in each tank in parallel is then collected from each tank, and the treated water is supplied to the third tank. After flowing into the second tank 2C, the wastewater is also subjected to the same wastewater treatment, and then flows into the fourth tank 2D. The wastewater is similarly subjected to the wastewater treatment, and is supplied to the second step.

FIG. 5 is a schematic configuration diagram of a conventional two-stage activated sludge treatment apparatus. The wastewater treatment apparatus of FIG. 5 can be regarded as a two-stage series connection of the activated sludge treatment method of the second step of FIG. The raw water 1 enters the aeration tank 21 and undergoes biological treatment. The activated sludge mixture 22 enters the sedimentation tank 23, and the supernatant water 24 is sent to the aeration tank 26 in the second step, and is precipitated in the sedimentation tank 23. The sludge is returned to the aeration tank 21 as sludge 25.
In the second step, the supernatant water 24 is further treated in an aeration tank 26, the activated sludge mixture 27 enters a settling tank 28, and the supernatant water is taken out as treated water 29 and settled in a settling tank 28. The returned sludge is returned to the aeration tank 2 as sludge 30
Return to 6. In FIGS. 1 to 4, the higher the raw water concentration flowing into the first step is, from the viewpoint of space saving, within a range where the aeration and stirring power required for oxygen supply does not become extremely high, from the viewpoint of space saving. 1000 mg / liter or more is desirable.

The carrier to be put into the fluidized-bed biological treatment tank, which is the first step, is not particularly limited as long as it has the ability to adhere and grow microorganisms, maintain and flow. However, it is needless to say that it is more advantageous to use a carrier which can maintain the volume load as high as possible and has a high organic matter removal performance from the viewpoint of space saving. The carrier to be used includes, for example, sand particles or granules such as plastic, polyurethane, resin, rubber and the like. It is preferably porous from the viewpoint of the adhesion of microorganisms.
Is preferable. The size of the carrier is preferably about 0.3 to 30 mm in diameter from the viewpoint of the retention and fluidity of the microorganism.

In the wastewater treatment system of the present invention, there is no need to provide a sedimentation basin (tank) between the aeration tanks of the first step and the second step, and the effluent of the first step is returned to the upstream part of the first step. You don't have to. Further, there is no need to return the excess sludge generated in the second step to the first step. Examples of the air supply means in the first step include aeration type and mechanical stirring type aeration devices, but are not particularly limited as long as the retention and fluidity of microorganisms attached to the carrier can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a conventional two-stage activated sludge treatment apparatus (comparative example) and a two-stage biological treatment apparatus using a combination of the fluidized-bed biological treatment method and the activated sludge treatment method of the present invention (implementation). An example in which high-concentration organic wastewater is treated using Example) will be described in more detail. However, the present invention is not limited to only these examples.

Comparative Example 1 Using the apparatus shown in FIG. 5, food-based organic wastewater (BOD = 1000 mg / liter) was supplied to the activated sludge treatment apparatus (aeration tank 10 liter, sedimentation tank 15 liter) as the first step. The operation was carried out at a BOD volume load of 10 kg / m ³ · day. As a result, a first step effluent having a BOD of 400 mg / liter was obtained. Further, as a result of treating the effluent of the first step with the activated sludge treatment apparatus (aeration tank 40 liters, sedimentation tank 15 liters) of the second step by operating at a BOD volume load of 1 kg / m ³ · day, BOD = 4
A second step effluent of 0 mg / l was obtained. Table 1 shows the processing results.

[0019]

[Table 1]

EXAMPLE 1 Using the apparatus shown in FIG. 1, a food-based organic wastewater (BOD = 1000 mg / liter) was fed to the first step, a one-tank type fluidized-bed biological treatment apparatus (tank volume: 10 liters). , BOD
The treatment was performed by operating at a volume load of 10 kg / m ³ · day. In addition, as a biological carrier, a carrier made of polyurethane was added at 30% with respect to the tank volume of the treatment water tank. As a result, BOD
= 400 mg / litre first stage effluent was obtained.
Further, the effluent from the first step was treated in an activated sludge treatment apparatus (aeration tank 40 liters, sedimentation tank 15 liters) in the second step by operating at a BOD volume load of 1 kg / m ³ · day. = 40 mg / l of the second step effluent was obtained. Table 2 shows the processing results. As a result of performing the above treatment, the conventional two-stage activated sludge treatment method (Comparative Example 1)
In comparison with the above, a processing capacity equal to or higher than that of a tank having a tank volume 19% smaller was obtained.

[0021]

[Table 2]

Example 2 Using the apparatus shown in FIG. 2, each of the treated water tanks had the same volume (the first tank 1).
0 liter), the food-based organic wastewater (BOD = 1000 mg / liter) was added to the first tank of the two-tank fluidized-bed type biological treatment apparatus (first step).
Operated at a volume load of 10 kg / m ³ · day, effluent from the first tank against the second tank (BOD = 100 mg / liter)
Was treated with a BOD volume load of 4 kg / m ³ · day. In addition, as a biological carrier, a carrier made of polyurethane was filled by 30% with respect to the tank volume of each treatment water tank. As a result, a first step effluent having a BOD of 40 mg / liter was obtained. Further, as a result of operating the effluent of the first step in the activated sludge treatment apparatus (aeration tank 4 liters, sedimentation tank 15 liters) of the second step by operating at a BOD volume load of 1 kg / m ³ · day, BOD = second of 4 mg / liter
Process effluent was obtained. The results are shown in Table 3.

[0023]

[Table 3]

As a result of the above treatment, the tank volume was reduced by 51% and 1% compared to the conventional two-stage activated sludge treatment method (Comparative Example 1).
Compared to a two-stage biological treatment apparatus (Example 1) using a combination of a tank-type fluidized-bed biological treatment method and an activated sludge treatment method,
Comparable or better throughput was obtained with a 0% smaller tank.

Example 3 Using the apparatus shown in FIG.
Liters, 4 liters in the second tank, 1.6 liters in the third tank, and 0.64 liters in the fourth tank.
Food-based organic wastewater (BOD = 1000 mg / liter) was fed into the 4-tank fluidized-bed biological treatment device (first step).
The volume load of each treated water tank was 10 kg /
The operation was performed in m ³ days. In addition, as a biological carrier, a carrier made of polyurethane was added in an amount of 30% based on the tank volume of each treatment water tank. As a result, a first step effluent having a BOD of 26 mg / liter was obtained. Further, the effluent from the first step is subjected to an activated sludge treatment apparatus (aeration tank 2.
56 liters, settling tank 15 liters)
As a result of operating at a volume load of 1 kg / m ³ · day, B
A second step effluent with an OD = 2.6 mg / l was obtained. Table 4 shows the processing results.

[0026]

[Table 4]

As a result of the above treatment, the tank volume was reduced by 58% and 1% compared to the conventional two-stage activated sludge treatment method (Comparative Example 1).
48 compared to a two-stage biological treatment apparatus (Example 1) using a combination of a tank type fluidized bed biological treatment method and an activated sludge treatment method.
%, And a two-stage biological treatment apparatus using a combination of a two-tank fluidized-bed biological treatment method and an activated sludge treatment method (Example 2)
As compared with the above, the same or higher processing capacity was obtained in a tank 13% smaller.

[0028]

According to the present invention, the first step of treating high-concentration organic wastewater by the fluidized bed biological treatment method and the second step of treating the effluent of the first step by the activated sludge treatment method are combined. By the two-phase biological treatment method, the processing space of all treatment steps can be significantly reduced in size and energy can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a processing apparatus used in a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a processing apparatus used in Embodiment 2 of the present invention.

FIG. 3 is a schematic configuration diagram of a processing apparatus used in Embodiment 3 of the present invention.

FIG. 4 is a schematic explanatory view of a modified row of the 4-tank fluidized-bed biological treatment tank of FIG. 3;

FIG. 5 is a schematic configuration diagram of a conventional two-stage activated sludge treatment apparatus.

[Explanation of symbols]

 Reference Signs List 1 raw water 2 fluidized bed biological treatment tank 2A first tank 2B second tank 2C third tank 2D fourth tank 3 carrier 4 air 5 activated sludge mixed liquid 6 aeration tank 7 activated sludge mixed liquid 8 sedimentation tank 9 treated water 10 return Sludge 21, 26 Aeration tank 22, 27 Activated sludge mixture 23, 28 Settling tank 24 Supernatant water 25, 30 Returned sludge 29 Treated water

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuichi Muranaka 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Works Co., Ltd. (72) Inventor Kazuo Fujita 111-1 Haneda Asahi-cho, Ota-ku, Tokyo Stock (72) Inventor Akira Kawakami 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Yuichi Fuchu 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside Ebara Corporation F term (reference) 4D003 AA12 AB02 BA02 CA03 CA07 EA01 EA19 EA23 EA30 4D028 AB00 BB02 BB06 BC13 BC14 BC18 BD06 BD16

Claims (4)

[Claims] 1. A first step in which high-concentration organic wastewater is treated by a fluidized-bed biological treatment method, and the effluent in the first step is directly treated by an activated sludge treatment method, and the treated water is subjected to solid-liquid separation to form sludge. A method for treating high-concentration organic wastewater, comprising combining a second step of separation. 2. The treatment step in the fluidized bed biological treatment method, which is the first step, is divided into multiple tanks, and the treatment is stabilized by reducing the load on the subsequent stage from that of the preceding stage. The method for treating high-concentration organic wastewater according to the above. 3. The BOD load in each tank is substantially reduced by dividing a treatment water tank of the fluidized bed biological treatment method, which is the first step, into multiple tanks and dividing each tank by a fixed ratio at a later stage. 2. The method for treating high-concentration organic wastewater according to claim 1, wherein the treatment efficiency is improved by setting the same. 4. A combination of a first step comprising a fluidized bed biological treatment tank, and a second step comprising an activated sludge treatment tank for introducing effluent from the fluidized biological treatment tank and a solid-liquid separation device. A high-concentration organic wastewater treatment device characterized by the following: