JPS62136295A - Method and apparatus for treating waste water - Google Patents

Abstract

PURPOSE:To enhance the treatment efficiency of waste water, by a method wherein the cross-sectional area of the upper part of a draft tube is made larger than that of the lower part and both of upper and lower parts are connected and an accumulation bed comprising solid particles is fluidized by the convection passing through an opening part. CONSTITUTION:Waste water is received in a fluidized tank 1 in an amount to be treated and mixed with solid particles. Sedimenting solid particles are pushed up along with a recirculation stream by the rising action of air of an air diffuser 7 blown in from the lower part of a draft tube 3 to be fluidized. The fluidized solid particles are accumulated not only between the draft tube 3 and a solid-liquid separation tower 5 but also the underside of the solid-liquid separation tower 5 and the inclined surface of a solid separation part 8 and collapsed from the lower part thereof by the convection passing through the opening parts 3d... provided to the inclined surface part 3c of the draft tube 3 to be fluidized. By this method, waste water is increased in the contact with solid particles to undergo purifying treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" This invention is a method of dissolving solid particles (microbial carriers) to which microorganisms are attached or encapsulated into wastewater using F! ! The present invention relates to a fluidized bed wastewater treatment method and apparatus for purifying wastewater.

"Conventional technology As is well known, in this fluidized bed method, it is an essential condition that solid molecules are continuously used in a suspended state of fluid in a treatment tank.

As a wastewater treatment apparatus used in such a fluidized waste method, a RANO having a structure shown in FIG. 3 is conventionally known. As shown in the figure, this processing apparatus consists of a fluidization tank 1 and a settling tank 2. The fluidization tank I has a draft tube 3 erected in its center, an overflow base 4 at the top, and a solid-liquid separation bath (outer cylinder pipe) 5 between the weir 4 and the duplex 3. It is something that is established. draft dupe 3
An air diffuser 7 connected to the electric blower 6 is provided at the lower part of the air conditioner.

In such a wastewater treatment device, the wastewater in the fluidized tank I is
The rising action of the air blown into the bottom of the tank from the air diffuser 7 causes it to flow and circulate in the direction of the arrow in the figure, and as the wastewater circulates and flows, solid particles are also circulated and come into contact with the wastewater, thereby causing the wastewater to flow and circulate. Purification will be carried out. Here, as the solid particles, a carrier having a specific gravity of more than 1 is used, such as sand, anthracite, activated carbon, microbial enclosing body, etc., and microorganisms are attached to or encapsulated on the surface of the solid particles.

Next, the purified wastewater has solid particles removed in a solid separation section 8 between the overflow base 4 and the same bath 5 for solid-liquid separation, and then flows over the overflow base 4 to become effluent water. It is designed to be sent to settling tank 2.

In the wastewater treatment method using this wastewater treatment equipment, a fluidized tank l
If you increase the amount of particles filled inside, the total surface area of the particles will increase, or the amount of microorganisms contained will increase, and the amount of microorganisms retained in the tank will increase, so it is possible to avoid increasing the reaction rate of waste removal. There are advantages that can be achieved.

"Problems to be Solved by the Invention" However, in addition to the 111 points mentioned above, the wastewater treatment method using such a wastewater treatment device also has the following problems.

In other words, from the point of view of processing efficiency, it is sufficient to increase the amount of particles as described above, but if the amount of particles is too large, it will be difficult to completely fluidize the solid particles, and some of them will flow into the fluidized tank I.
It tends to accumulate at the bottom of the tank, and if it is increased further, it will not flow at all. Furthermore, when the amount of particles is large, solid particles tend to settle in the tank due to slight fluctuations in operating conditions such as fluctuations in blowing air pressure, and the flow of particles and furthermore, the circulation of the liquid itself tends to stop. When the particles are deposited in this way, as shown in Fig. 4, not only the lower outer peripheral part of the draft tube 3 (section A in the figure) but also the inside of the draft tube 3 reach a position higher than the surface of the deposited particles in the outer peripheral part. Solid particles begin to accumulate (part 8 in the figure). In this state, even if gas is blown into the air diffuser 7, the gas will be blocked by the accumulated particles in the 8 parts of the draft tube 3 and will escape to the outer periphery of the draft tube 3, making it impossible to fluidize the solid particles again. There was a drawback that it could lead to a fatal situation such as running out.

For these reasons, there is a limit to the amount of solid particles that can be added into the fluidized fluidized tank 1, and the amount added to the tank volume is about 15-18% at most, and 5-18% during normal processing.
It was about 12%. With this amount of solid particles added,
Wastewater treatment efficiency was poor, and in order to improve the efficiency, the volume of the fluidized tank had to be increased, which led to problems such as increased costs due to the expansion of equipment.

"Means for Solving the Problem" Therefore, according to the wastewater treatment method of the present invention, the cross-sectional area of the upper part of the draft tube is made smaller than the lower part, and the upper part and the lower part are connected by a connecting part, and the upper part An opening is formed in either or both of the connecting parts, and the deposited layer of solid particles deposited between the draft tube and the outer tube is collapsed and fluidized by convection passing through the opening. By doing this, the above problem was solved.

Furthermore, the wastewater treatment device of the present invention includes a fluidized tank having an aeration device at the bottom, a draft tube and an outer cylindrical pipe installed vertically in the fluidized tank, and the cross-sectional area of the upper part of the draft duplex is made smaller than that of the lower part. The above problems are solved by increasing the size, connecting the upper and lower parts by a connecting part, and forming an opening in either or both of the upper part and the connecting part.

"Example" Hereinafter, the wastewater treatment method of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a wastewater treatment apparatus of the present invention, and in the figure, parts common to those of the conventional apparatus shown in FIG. 3 are given the same reference numerals to simplify the explanation.

The structure of the wastewater treatment device shown in FIG. 3a and the lower part 3b are connected by an inclined surface part (connection part) 3c, and a circular opening part 3d is formed in this inclined surface part 3C.

The cross-sectional area of the upper part 3a of the draft tube 3 is the first
In the figure, it is desirable that the cross-sectional area of the fluidized bed 1 at position A is 30% or more. Generally, it is preferably 50% or more. The ratio of the outer diameter of the draft duplex 3 to the outer diameter of the solid-liquid separation circle (outer cylindrical tube) 5 is about 60 to 85%, preferably about 70 to 82%.

Further, the shape of the openings 3d may be any shape other than a circle, such as a rectangular shape or a slit shape.

It is desirable that the openings 3d are formed at equal intervals on the sloped surface 3c of the draft tube 3, and the number and cross-sectional area of each opening 3d is determined by the distribution of the openings 3d... formed on the outside of the sloped surface 3c. It is determined by taking into account that the deposited particle layer can be collapsed by convection passing through the openings 3d..., but it is determined that the total cross-sectional area of the openings 3d... It is preferably 50 to 120%.

Next, a wastewater treatment method using the wastewater treatment apparatus having such a configuration will be explained. First of all, the wastewater is a fluidized tank! A predetermined processing amount is accommodated in the chamber, and mixed with solid particles such as diatomaceous earth at an appropriate mixing ratio. Since the solid particles have a specific gravity greater than 1, they naturally settle in the wastewater, but the settling solid particles are caused by the upward action of the gas from the diffuser 7 blown from the lower part of the draft tube 3 together with the circulating flow. It is pushed up and fluidized. A part of the solid particles fluidized in this way circulates down along the wall of the fluidization tank l via the openings 3d, and a part rises up the upper part 3a of the draft tube 3 and enters the draft duplex. 3 and descends between the draft tube 3 and the solid-liquid separation circle diameter 5, and between the draft tube 3 and the solid-liquid separation circle diameter 5 and between the lower side of the solid-liquid separation bath 5 and the solid. The particles are deposited from above between the inclined surface of the material separating section 8, and a substantially doughnut-shaped deposited particle layer is formed here. Here, the convection that passes through the openings 3d... is a flow both in and out.
In general, the upper part of the opening 3d... enters the draft tube 3, and the lower part of the opening 3d...
It's leaking outside. The above deposited particle layer is formed in the opening 3d provided in the inclined surface portion 3c of the draft tube 3.
It is gradually collapsed from the bottom by the convection current passing through it, and is fluidized again. Such flow increases the contact of the wastewater with solid particles and thereby purifies it.

After the purified wastewater has solid particles removed in the solid separation section 8 between the overflow weir 4 and the solid-liquid separation diameter 5, it crosses the overflow weir 4 and becomes runoff water. and sent to settling tank 2.

The above wastewater treatment method was for aerobic wastewater treatment, but when performing anaerobic wastewater treatment, the upper part of fluidized tank I is sealed in Fig. 1. The air diffuser 7 is equipped with a pipe 9 that connects it to the electric blower 6.
The gas from the electric blower 6 sent into the fluidized tank 1 via the fluidizer is recovered at the upper part of the fluidizer III, and is circulated and supplied to the electric blower 6 again. In this way, it is possible to perform anaerobic wastewater treatment using this wastewater treatment device.

Further, in the above embodiment, the openings 3 (1...) of the draft duplex 3 are formed in the inclined surface part 3c, but the portion where the openings 3d... can be formed is not limited to the inclined surface part 3c. , as shown in FIG. 2, there is an opening 3d in the upper part 3a...
It may also be a purchase that has been formed.

Furthermore, in the above embodiment, the connection part that connects the upper part 3a and the lower part 3b of the draft tube 3 of the wastewater treatment apparatus is formed into an inclined surface part 3C having an inclination angle, but the connection part does not have an inclination angle. A horizontal plane is also possible.

Hereinafter, the effects of this invention will be clarified by showing experimental examples.

[Experiment example! ]

The amount of solid particles that can be filled into the fluidized tank of the wastewater treatment apparatus shown in FIG. 1 was compared with the amount of solid particles that can be filled into a conventional fluidized tank. The volume of the fluidized tank is the same in both cases, and the amount of wastewater flowing into the fluidized tank is also the same. In the comparative study, the criterion was whether or not the solid particles filled inside the fluidized tank could flow. Also,
The main specifications of the fluidized tank used are as follows.

Height of fluidized tank・・・・・・・・・・・・・・・・・・
...3300mm outer diameter of solid-liquid separation column...
・・・・・・500mm Upper outer diameter of draft tube...400mm Lower outer diameter...200m
m Note that the solid particles used were diatoms with a diameter of 0.3 to 0.6 mm (Table 1) and activated carbon with an average diameter of 0.6 mm (Table 2). The numerical values in Tables 1 and 2 are the amounts of solid particles added to the volume of the fluidized tank.

Table 1 Table 2 As is clear from these results, in any case, the device that satisfies the requirements of this invention can add about 2 to 3.5 times more flowable particles than the conventional radish. Therefore, it can be seen that the wastewater treatment efficiency can be improved by the amount of increased particles.

[Experiment Example 2] Solid particles were added to the fluidized tank of the wastewater treatment equipment shown in Figure 1 at different rates relative to the volume of the fluidized tank, and the inside of the upper part of the draft tube and the outer part of the lower part of the draft tube during fluidization were The density of solid particles at the location was measured. The measurement results are shown in Table 3. Note that the solid particles contain 0.
Diatomaceous earth with a diameter of 3 to 0.6 mm was used.

Table 3 Unit of particle density: Volume % when allowed to settle still.

As is clear from this result, the particle density at the mouth position is
The particle density increases in proportion to the particle addition rate, and it is always higher than the particle density at the position C.
That is, it can be seen that a circulating flow of solid particles occurs inside the upper part of the draft tube without passing through the bottom of the fluidization tank. In a fluidized bed using particles with a specific gravity greater than 1, as the number of particles is increased, the bottom of the fluidized bed is generally clogged and cannot flow, but it is possible to increase the amount of particles retained at the top of the fluidized bed. This is prevented by. That is, there are many solid particles that are convecting inside the draft tube, and some of these solid particles settle inside the draft tube due to their own weight and circulate down along the wall of the fluidization tank via the opening. The remainder of the solid particles rises over the top of the draft tube, passes over the top end of the draft tube, and descends between the draft duplex and the solid-liquid separation circle to form a layer of deposited particles from above. This deposited particle layer is gradually collapsed from the bottom by convection passing through the opening provided in the inclined surface of the draft dupe, and is again fluidized.

"Effects of the Invention" As explained above, according to the present invention, it is possible to increase the amount of solid particles held in the upper part of the fluidized fluidization tank when the blowing air pressure fluctuates, thereby providing an excellent effect of preventing solid particles from clogging. can be obtained. Further, according to the present invention, solid particles can be sufficiently fluidized in the fluidized tank without causing clogging even if the amount of solid particles added is large. The amount of microorganisms that can be used can be significantly increased, and the efficiency of wastewater treatment can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of the wastewater treatment apparatus of the present invention, and FIG. Figure 3 is a configuration diagram of a conventional fluidized bed wastewater treatment equipment, and Figure 4 is a state diagram when the flow of solid particles in the fluidized tank stops and particles accumulate in a conventional fluidized bed wastewater treatment equipment. be. ■...Fluidization tank 3...Draft tube 5...Circle diameter for solid-liquid separation (outer cylinder tube) 7...
...Air diffuser.

Claims (2)

[Claims] (1) Wastewater is introduced into a wastewater treatment device consisting of a fluidized tank with an aeration device at the bottom, a draft tube and an outer cylindrical pipe installed vertically in the fluidized tank, and microorganisms are attached or In the wastewater treatment method of purifying wastewater by flowing solid particles that are contained and have a specific gravity larger than 1 through the aeration device, the cross-sectional area of the upper part of the draft tube is larger than that of the lower part, and the upper part and the lower part are connected. In addition to being installed in a row depending on the department,
An opening is formed in either or both of the upper part and the connecting part, and the deposited layer consisting of solid particles deposited between the draft tube and the outer tube at the upper part of the draft tube and the connecting part is formed through the opening. A wastewater treatment method characterized by disintegration and fluidization by passing convection. (2) Consisting of a fluidized tank having an air diffuser at the bottom, a draft tube and an outer cylindrical tube installed upright within this fluidized tank, the cross-sectional area of the upper part of the draft tube being larger than that of the lower part, and A wastewater treatment device characterized in that an upper part and a lower part are connected to each other by a connecting part, and an opening is formed in either or both of the upper part and the connecting part.