JPS5851986A - Apparatus for biologically purifying waste water with aerobes - Google Patents

Abstract

PURPOSE:To enhance the effect of biological treatment and to improve the efficiency of purifying waste water, by providing a packed layer formed by uniformly mixing solid particles having a particle size of 0.2-10mm. and a filler larger than the particles and a supporting layer for the packed layer inside a purifying cell. CONSTITUTION:Waste water containing BOD components, nitrogen components, etc. is let flow from raw water piping 2 into a purifying cell 1, while air is fed from piping 7 through a water-collecting air-introducing means 5 into the cell 1 to maintain a packed layer 3 in an aerobic atmosphere. While the waste water passes through the packed layer 3, BOD components, etc. in the waste water adhere to and grow on the surface of the filler to form biomembranes of aerobes such as BOD component-decomposing bacteria and nitrifying bacteria. Consequently, BOD components, etc. in the waste water successively flowing downwards through the packed layer 3 are decomposed and removed by the action of the aerobic biomembranes. Ammoniac nitrogen and organic nitrogen are oxidized into NO3-N and NO2-N, while purified water is withdrawn through the water- collecting means 5 and a draining opening 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aerobic biological treatment device for wastewater, and more particularly, to a wastewater treatment device that biologically purifies wastewater under aerobic conditions using a biofilm. It is.

To purify organic wastewater containing nitrogen compounds and other organic substances,
Biological methods are generally employed.

In biological methods, organic substances, especially BOD components, indicated by indicators such as BOD-'Pc0D, are oxidized and removed by microorganisms. In other words, ammonia nitrogen is oxidized (nitrified) to nitrate nitrogen or nitrite nitrogen by nitrifying bacteria under aerobic conditions, and then reduced to nitrogen gas (denitrification) by denitrifying bacteria under anaerobic conditions and removed. Ru.

By the way, an activated sludge method using suspended sludge is known as a biological treatment method for removing BOD components and nitrification under aerobic conditions. In this method, treated water and suspended sludge are brought into contact with each other in a treatment tank with aeration to perform oxidation, and then the mixture of treated water and suspended sludge is transferred to a settling tank, where the sludge settles and is separated from the treated water. . The treated water is either discharged as is or introduced into the next treatment tank, the settled sludge is pulled out and a portion is returned to the original treatment tank for reuse, and the rest is disposed of as surplus sludge. This method has an extremely slow processing speed and requires a long time to process, so large-capacity equipment is required to treat a large amount of wastewater. In addition, a phenomenon called bulking occurs, causing the sludge to settle, causing the sludge to flow out together with the treated water, reducing the quality of the treated water, and in severe cases, causing the sludge in the treatment tank to disappear, resulting in biological treatment itself. There is also the problem that it stops progressing. Furthermore, it has been pointed out that since the oxygen absorption efficiency is low, a large amount of air must be blown in to maintain aerobic conditions, which increases power costs.

On the other hand, there is a biofilm method as a biological treatment method other than the above-mentioned activated sludge method.
There are methods such as the immersion offshore method and the rotating disk method.

These methods purify wastewater using a microbial film attached to the surface of plastic fillers, honeycomb tubes, solid particles, disks, etc. filled in the treatment tank as biofilm media. It has advantages such as easy maintenance and management since there is no need to send it back and bulking does not occur. However, these methods have two problems: ■ The biofilm area per tank volume is relatively small and the treatment capacity is low; ■ The SS components in the treated water and the microbial film detached from the biofilm medium flow out of the tank together with the treated water. There are drawbacks such as the need for separate solid-liquid separation operations.

In view of the above-mentioned circumstances, the present invention was completed as a result of intensive research to solve the problems of treatment capacity and treated water quality that have been pointed out in the biofilm method. The biological treatment of wastewater consists of a treatment tank provided with a wastewater introduction part and a treated water discharge part at the bottom. f of j-
A treated water collection device and an air intake device are installed on the side, =
The gist of the i+ filled kA layer is that solid particles having a particle size of 0.2 to 10IIJI and a filler that is sufficiently larger than the solid particles are uniformly mixed and filled.

The structure and effects of the present invention will be explained below based on the drawings showing examples, but the following are representative examples and are not intended to limit the present invention, and will be limited to the extent that can comply with the spirit of the above and below. It is free to change the shape and structure of the treatment tank body, the configuration of the treated water collection device and air introduction device, or the piping for the treated water, etc., and all of these are included in the scope of the technology of the present invention. .

FIG. 1 is an explanatory diagram conceptually showing the processing device of the present invention, and FIG.
The figure is a cutaway diagram of the main parts of the treatment equipment, in which 1 is the treatment tank, 2 is the treated water storage tank, 3 is the packed bed, 4 is the support layer, and 5 is the collection of the treated water and the introduction of air for aeration. A water collection/air introduction device M (details will be described later), 6 indicates a raw water introduction pipe, 7 indicates an air pipe, and 8.9 indicates a treated water pipe. A water collection/air introduction device 5 is arranged at the bottom of the treatment tank 1 to not only collect treated water but also to disperse backwash water and air throughout the treatment tank 1.
A support layer 4 is disposed above the support layer 4, and a filling layer 3, which is the most characteristic feature of the present invention, is disposed above the support layer 4. A deep part 14 is formed at a suitable position at the bottom of the treatment tank 1.
A treated water outlet 15 is provided on the lower wall surface, and an air pipe 7 for supplying air to the water collection and air introduction device 5 is arranged. In FIG. 1, reference numeral 10 indicates a backwash pump used when backwashing the packed bed 3, 13 indicates a valve, and 11 indicates a discharge pipe for backwash water. FIG. 3 is an enlarged cutaway diagram showing the water collection/air introduction device 5, in which two reinforcing plates 5b are inserted into the rectangular cylindrical body 5a, and the upper wall of the rectangular cylindrical body 5a and the reinforcing plate 5b are arranged. A large number of through holes 5C are bored in the cylindrical body 5C, and a large number of rectangular cylindrical bodies 5a are arranged on the bottom of the treatment tank 1 as shown in FIG. 2 to form a water collection and air introduction system. 5 is composed. Therefore, as will be described later, the treated water that has been purified while passing through the packed bed 3 and the support layer 4 enters the rectangular cylinder 5a through the through hole 5C, flows along the bottom toward the bottom 14, and exits the tank from the discharge port 15. is discharged to. Also, from the air pipe 7 to the rectangular cylinder 5a
The air sent inside is dispersed and rises from the entire lower surface of the processing tank 1 through the through hole 5C.

Wastewater treatment using such a device is carried out as follows. First, wastewater containing BOD components, nitrogen components, etc. is flowed into the treatment tank 1 from the raw water pipe 2, and air is sent into the tank 1 from the pipe 7 through the water collection/air introduction device 5 to make the packed bed 3 aerobic. Create an atmosphere. In the process of wastewater passing through the packed bed 3, BOD components in the wastewater adhere to and grow on the surface of the filling material, and an aerobic microbial film such as BOD component oxidizing bacteria and nitrifying bacteria is formed, which sequentially flows down inside the packed bed 3. BOD components, etc. in the wastewater are decomposed and removed by the action of the aerobic microbial membrane, and ammonia nitrogen and organic nitrogen are converted into N0a-N and NO.
Oxidized to 2-N. The treated water purified in this manner is taken out through the water collection/air introduction device 5 and the discharge port 15.

By the way, in order to efficiently proceed with the biological purification described above, it is necessary to increase the effective contact area of the aerobic microbial film formed on the surface of each filling material in the packed bed 3 with the wastewater, and to also It is necessary to rise while dispersing the air evenly and create an aerobic atmosphere throughout. Moreover, as the growth of the microbial film progresses, it falls off the surface of the filler and reduces the cleanliness of the treated water, so in order to prevent such problems, it is necessary to provide the filler bed 3 itself with an overflow effect. It is. However, in the conventional packed bed used in this type of equipment, the particle size of the packed material is too large and the effective area of the aerobic microbial membrane cannot be made large enough, resulting in insufficient biological purification effects. If the particle size of the packing material is too small, the air will not rise evenly through the entire packing bed, creating an anaerobic atmosphere in some areas and reducing the purification effect. I couldn't say that it was.

In contrast, in the present invention, the purification effect is significantly enhanced by adjusting the particle size structure of the filler constituting the packed bed. That is, the filler used is a homogeneous mixture of relatively fine solid particles with a particle size of 0.2 to 10 degrees, particularly preferably 0.4 to 7 degrees, and a filler that is sufficiently larger than the solid particles. However, the purpose cannot be achieved with a filler having a substantially single particle size as in the conventional example. However, the inventors have confirmed through experiments that: (1) In the case of only the filling, the air rises uniformly throughout the packed bed, but because the surface area is small, the effective area of the microbial film is sufficiently large. I can't do it,
Furthermore, since the porosity of the packed bed is large, bubbles tend to grow into large particles during the rising process, which tends to slow down the activity of microorganisms, and the removal effect of microbial membrane debris is poor. On the other hand, in the case of only fine packing, the effective area of the microbial membrane can be increased due to the large surface area, and the removal effect of microbial membrane debris is also high, but since the porosity of the packing is small, air The entire packed bed is not raised evenly, and an anaerobic atmosphere is formed locally, reducing the purification effect. In addition, the packed bed is likely to become clogged, requiring frequent backwashing.

However, when using a homogeneous mixture of fillers and fine fillers,
It takes advantage of the features of both, eliminates their drawbacks, and exhibits an outstanding purifying effect. Here, the particle size of the solid particles is 0.2
~], Ow is set in order to simultaneously satisfy the diffusibility of air, effective surface area of microbial film, treatment efficiency, Oki-over effect, etc., and for fine particles of less than 0.2 order, the diffusivity of air and The treatment efficiency decreases, and if the amount exceeds 10 fl, the effective surface area of the microbial film becomes insufficient and the overflow effect becomes poor, both of which fail to achieve the object of the present invention. Further, the filler has the effect of increasing air diffusivity and increasing processing efficiency and backwashing efficiency, and it is sufficient that the filler is sufficiently larger than the solid particles, and it is difficult to specify the particle size. However, the most practical particle size is between 25 and 300 mm, with 60 mm being particularly preferred.
~300, and it is preferable to select from those within the above particle size range, taking into consideration the size of the processing tank and the particle size of the solid particles used together. It is essential that the solid particles and filler be mixed uniformly when filling. If the mixing is insufficient, air and raw water will concentrate in uneven parts of the filler, and the purification effect will be extremely reduced. At the same time, the backwashing efficiency also decreases. Although the blending ratio of the two is not particularly limited, it is preferable that the filler is filled in an apparent volume of 50 to 100% of the volume of the filled bed. The porosity of the packed bed 3 varies depending on the blending ratio of the two, but it is about 50% for solid particles (in the case of sand) alone and about 70 to 95% for the filler alone, so air diffusivity,
The porosity is set to a value between the above individual porosity values, taking into consideration biological treatment effects, offshore effects, etc. In the actual filling method, it is difficult to form a packed layer all at once, and the process of filling solid particles into the pores of the filler, which have been tightened to a certain extent, and adjusting the filling uniformly with water or air is carried out in stages. A method of forming a layer of constant height is preferred.

As the solid particles mentioned above, all conventionally known filling materials such as sand, anthracite, blast furnace slag, and plastic particles can be used, and the shape is not limited to spherical shapes, but also pellet-like, All types of fillers can be used, including short columnar shapes and irregularly shaped crushed pieces.Furthermore, various types of fillers such as Raschig rings and Lessing-shaped fillers used in gas-liquid contact devices, pipes, spheres, and irregular shapes can be used. Gravel, various lattice containers, etc. can all be used.

The support layer disposed below the packed bed is provided to prevent fine solid particles in the packed bed from leaking out from the through holes 5C of the water collection/air introduction device 5. Gravel, etc. with a slightly larger diameter is used.

In addition, as the water collection/air introduction device 5, an A/W type Leo Leobold block type developed by Shindo Faudler ■ is shown, which is the best in that it can feed air from the entire bottom surface of the treatment tank. It is of course possible to use water collection devices such as a perforated block type, perforated pipe type, perforated plate type, boiler set, T-block type, and strainer type, which are effective. It is also possible to provide a separate air blowing pipe in the support layer or the like to supply aeration air from a location different from the water collection device.

The present invention is roughly constructed as described above, but the point is that by using a uniform mixture of fine solid particles and fillers as the filler in the packed bed, wastewater treatment has a high purification effect as listed below. I was able to obtain the equipment.

(1) Due to the presence of the filler, aeration air is uniformly supplied to the entire layer of the filler I, so the entire layer can be maintained in an aerobic atmosphere, increasing the biological treatment effect.

Furthermore, the entire packed bed can be made to have an appropriate porosity, and the efficiency of wastewater treatment and backwashing can also be improved.

(2) The presence of fine solid particles expands the effective surface area of the microbial membrane and also promotes the formation of fine bubbles in the aeration air, further increasing the biological treatment efficiency.

In addition, the solid particle-filled section also has the effect of removing microbial membrane debris and SS components in wastewater, thereby increasing the cleanliness of the treated water.

Next, examples will be given to clarify the effects of the present invention.

Example 1 A treatment tower with a diameter of 200 fi and a height of 3,500 m was used for experiment purposes, a water collection/air introduction device was placed at the bottom, and gravel with a particle size in the range of 2 to 20 tml/g was filled on top according to the particle size. It was used as a support layer. In this upper layer, sand with a particle size of 0.4 to 3 mm is used as solid particles, magnetic spheres of 2560 and lessing-like filler of 25 mm are used as fillers, and the apparent volume of the filler is equal to the volume of the packed bed. ioo% filling, and the voids were filled with solid particles (401 fillings of lessing-like filler were filled, and the spaces were filled with solid particles). The filling is filled to a bed height of 1300 m (filling volume 401). Using this treatment tower, 200% of BOD components mainly consisting of peptone
ppm synthetic sewage was treated under the following conditions and the removal rate of BOD components was investigated.

Treated water IT: 1m'/day LV: 32rn/day Treated water temperature = 25℃ SV: 1"/hBOD load = 5 instant/d
- Day Air amount: 1.7 Ntrt/day Number of backwashing = 2 times/day The results are shown in Table 1.

Table 1 As is clear from Table 1, the BOD removal rate is low when sand as solid particles is used alone, but the BOD removal rate can be significantly increased by using a mixture of sand and filler. I can do it.

Example 2 Filling 1-
was formed, and the primary treated sewage water was treated under the following conditions.

Treated water m: 1.7a, r/day LV: 65m/day SV: 1.81/h BOD load = 4.6-7.1 instant/d・day Air blowing amount: 2
．． 2 Nyv/day Air lid/Amount of treated water: 1.3 Treated water temperature: 17-21°C Number of backwashing: 3 times/day The results are shown in Table 2.

As is clear from Table 2, no matter which mixed filler is used, the BOD value of the treated water is 20 ppm or less, SS
The content is 15 ppm or less, and a high purification effect can be obtained. In addition, for those using granulated blast furnace slag and sand as solid particles, the BOD load is 8.5 to 1
The treatment was carried out at higher levels of 0 KF/day and 7.5 to 8 Vd/day, but in both cases the BOD value was 20 ppm.
The following treated water could be obtained.

Example 3 A water collection/air introduction device was placed at the bottom of a treatment tower with a diameter of 600 m and a height of 400 m (1 m), and gravel with a particle size of 2 to 20 M0 was filled on top to form a support layer. , lessing-like packing with a fighting diameter of 70 and granulated blast furnace slag with a diameter of 0.4 to 3 wxD were used, and the apparent volume of the filler was 100% of the packed bed volume, and the voids were filled with solid particles (Lessing (fill the space with solid particles).

Using this treatment tower, purification treatment was carried out under the following conditions using as raw water a wastewater obtained by removing phenol from ammonium water by penzol extraction and diluting it five times with gray water such as cooling water.

Treated water jii: 4.0m 7 days LV: tam/day SV: O151/h BOD load: 9.6KF/day Air blowing amount: 33Nm’/day Air volume/processed water volume: 7 Processing water wet: 23-25℃ Backwashing frequency: 2 times/day The results are shown in Table 3.

As is clear from Table 3, the BOD load is 9.6Kg/
It can be seen that BOD and phenol can be removed extremely efficiently even under a high load of -.

Example 4 A treatment tower was prepared in the same manner as in Example 1, except that a lessing-like packing with a diameter of 25 ff was used as the packing material, and granulated blast furnace slag with a diameter of 0.4 to 3 wmD was used as the solid particles. The secondary treated water was purified. During the treatment, a pH electrode was placed in the treatment tower to prevent a decrease in the pH within the packed bed, and an aqueous NaOH solution was added to adjust the pH to 7.0.

Treated water: 1, 2, 47 days LV: 38n/day SV: 1.25 1/h ]30D load: 0.4/door/day NHa-N load: 0.6 immediate/-day Air blowing amount: 1.2Ngo/day Processing water temperature: 25℃ Backwashing frequency: 1 time/day The results are shown in Table 4.

Table 4 As is clear from Table 4, this treatment resulted in NHa-N of 9
9% or more is removed, and BOD and SS components can also be removed efficiently.

Example 5 The same procedure as Example 4 was used, except that as the solid particles, granulated blast furnace slag of 0.4 to 3. A treatment tower was prepared in the same manner, and the secondary treated sewage water was purified.

During the treatment, the pH inside the column was adjusted to 9 using an aqueous NaOH solution.
The other treatment conditions were the same as in Example 4 except that an aqueous solution of CaCl2 was separately added into the column as a Ca source. The amount of Ca added was 100 ppm.

The results are shown in Table 5, and if the solid particles are subjected to dephosphorization treatment, phosphorus can be efficiently removed at the same time as nitrification.

+191 Table 5

[Brief explanation of drawings]

FIG. 1 is a schematic overall view illustrating the processing apparatus of the present invention, and FIG.
The figure is a partially cutaway sketch of the treatment tank, and FIG. 3 is a partially cutaway sketch showing an enlarged view of the water collection/air introduction device. 1. Treatment tank, 2. Treated water storage tank, 3. Filled bed, 4.
・・Support layer, 5.・Water collection/air introduction device, 6.・Raw water (
Wastewater) introduction pipe, 7... Air piping, 8, 9... Treated water piping, 10... Backwash pump, 15... Treated water outlet,
14...Fuchibe

Claims (1)

[Claims] (1) A biological treatment device for wastewater consisting of a treatment tank with a wastewater introduction section at the top and a treated water discharge section at the bottom, the treatment tank having a packed bed and a support layer for the packed bed, A treated water collection device and an air introduction device are provided below the support layer,
Wastewater aerobic biology characterized in that the packed bed is filled with a uniform mixture of solid particles having a particle size of 0.2 to 10 bait and a filler that is sufficiently larger than the solid particles. processing equipment.