JPS6349357Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a new invention in a wastewater treatment device, particularly a wastewater treatment device that can be used as a gray water generation device.

In recent years, large buildings being constructed in large cities are beginning to introduce gray water systems based on social demands such as energy conservation.

These gray water systems treat gray water and use it for flush toilets, car washes, watering, air conditioning equipment, etc., but especially when installed in buildings etc., they are small and have low treatment performance. A wastewater treatment system that is expensive and easy to maintain is required.

A wastewater treatment device that meets these demands is an aeration filtration type device that integrates standard activated sludge treatment and filtration functions.In other words, it is a treatment tank that combines the above two functions in one tank, with the upper part This is a microbial breeding retention area for biological treatment such as sludge treatment and biofilm method, and the lower part is made of filter material with relatively high specific gravity, such as gravel or sand, in order to filter the above-mentioned treated wastewater. Japanese Patent Publication No. 56-14360 discloses a compact treatment tank consisting of a filtration layer and an upper filtration layer made of a filter material whose specific gravity is smaller than that of the filter material of the lower filtration layer, such as anthracite or granular activated carbon. No., Japanese Patent Publication No. 57-48388
proposed in No.

As mentioned above, both of these methods involve immediately filtering the biologically treated water without going through the process of separating it from microbial sludge.
In the case of No. 14360, the sludge concentration of the mixed liquid in the microorganism breeding and retention area is high, which is disadvantageous as it places a burden on the filtration layer. We have an improved relationship. However, even this improved type of treatment tank has the following drawbacks.

In other words, during backwashing, the filter media such as sand that makes up the above-mentioned filtration layer collides with the microbial membrane based on corrugations or pipes that make up the microbial breeding and retention area, which causes peeling and biological treatment. This results in a deterioration of ability. Further, anthracite, sand, etc. of the filter medium may adhere to the above-mentioned exfoliated sludge, forming a sludge lump, and the corrugated plate or pipe-shaped contact material fixed in the microorganism retention area may become clogged.

Also, for both types, especially the Special Publication Showa 56-14360
In the case of No. 1, the dense and adsorbent sludge layer formed on the top surface of the filtration layer is smooth and smooth because it is based on fine-grained filter media.
Although it is good in terms of high-level physical filtration because it is formed to be uniformly thick, it has the drawback that it is unable to meet the requirement of being ``resistant to fluctuations in inflow load.''

On the other hand, if the inside of the aeration tank is maintained at a high MLSS state, it is resistant to inflow load fluctuations, difficult to decompose substances can be removed, the amount of sludge generated is reduced, and the aeration tank capacity can be reduced. Both filters use sand, sand, etc. as filter media, making it impossible to achieve high MLSS. This is because if the inside of the aeration tank is maintained at a high MLSS, sludge lumps are likely to form, and as a result, systems that use grit, sand, etc. as filter media will cause blockage in a short period of time.

In addition, since the discharge of sludge in the tank relies on an increase in the amount of backwash water, the amount of backwash water required to maintain a constant MLSS in the tank increases, and it is necessary to increase the capacity of each water layer to account for the amount of water. Ta. As a result, the installation space for the facility becomes large, which poses a problem in terms of maximizing the effective use of architectural space.

Furthermore, in locations where land costs are high, such as urban buildings, it is necessary to further reduce the space required for the equipment attached to the aeration filtration tank. A, installation space B for piping, operation valves, etc. had to be laid out occupying a separate planar area from the treatment tank C.

This proposal was developed based on a completely new idea in view of the above points, and its gist is that the microorganism breeding and retention area constructed in the aeration section for biological treatment of activated sludge, biofilm, etc. A cylindrical or spherical container in which a filling of fiber mass is placed in the lower part thereof with a predetermined free space configured to have a narrower planar area than the planar area of the aeration part, and the upper part thereof is covered with a net-like material for preventing outflow of the filter medium. By connecting a filtration tower made up of 100% filtration towers, and accommodating machines, valves, piping, etc. in the space formed at the bottom of the tank, and keeping the MLSS concentration in the tank high, the aeration section can be made smaller and negative fluctuations in the inflow can be reduced. In addition, by using a fiber mass filling, the filtration rate can be increased, making it possible to install a filtration tower in a part of the area of the aeration section. , space can be used more effectively, the equipment can be made more compact, and the backwashing of the filter media can be performed using only air, and the backwashing water tank itself does not discharge sludge due to the increased amount of backwashing water. It is very advantageous when installing inside a building because it can eliminate or make it smaller.

This will be explained in detail below based on the drawings.

Figures 2a and 2b are a plan view and a vertical cross-sectional view of the treatment tank 1 which has two functions of the present invention, in which a filtration section is constructed at the lower part of the aeration section 2 to have a narrow plane area compared to the plane area of the aeration section. 3 is connected to the aeration section 2, and an aeration pipe 4 is provided at the bottom of the aeration section 2, and a raw water pipe 5 is installed at the top.
A level controller 7 is provided. Excess sludge is discharged out of the system by a pump (not shown) (an air lift pump is also possible). The filtration section 3 is composed of a packed layer 8 using fiber lumps as a filter medium, and a mesh 10 for preventing the filter medium from flowing out is covered above the packed layer 8 at a predetermined level to ensure a stirring allowance 9 for the filter medium during backwashing. It consists of a cylindrical or spherical container tower.

The net-like material 10 is not limited to synthetic fiber or metal, and it is sufficient that the mesh is smaller than the minimum diameter of the fiber mass used and can withstand the water pressure of backwashing and water pressure during treatment. 10cm to 1.0cm above layer 8
Stretch horizontally over the entire surface at a distance of approximately 300 m.

Note that the filtration section 3 may be arranged on the side of the tank instead of at the center of the tank.

The above-mentioned fiber mass is formed by processing and molding thin short fibers with a fiber diameter of 10 to 100 microns into a small fluff ball shape, which is spherical or oblate oval with a diameter of 3 to 50 mm.

The first reason for this shape is to prevent the short fibers from flowing out through the holes in the partition plate during filtration or washing if they are used as they are.The second reason is to prevent this. , to facilitate the cleaning of the filter medium that has captured SS, that is, to facilitate the separation of the SS and the filter medium.

In other words, since the filter medium, which is a loosely compacted fiber mass, has a light specific gravity, it easily flows in water by blowing air, is vigorously stirred, and washed, but it is easy to separate the washed SS because the filter medium is large. .

In addition, the shape is spherical to improve fluidity in water during washing and to facilitate molding.

Therefore, the average porosity of the filter medium packed bed 8 of the present invention is
The specific surface area of the filter media layer is approximately 3000 m ² /m ³ , and the fiber mass is characterized by a large space (large SS trapping capacity) compared to a sand-filled filter media layer (porosity 50%).

The thickness of the packed layer 8 of such fiber mass is 10 cm to 1.0 m.
The filtration action in terms of degree is detailed as follows.

In other words, coarse SS in the water to be treated is captured in the gaps between the fiber masses, and fine SS enters the interior of the fiber masses and is mainly captured between the fibers.
SS acquisition is done in depth.

In addition, the fiber mass has a moderate elasticity, but when the filtration speed is high, the fiber mass in the lower layer is slightly deformed by water pressure during filtration and becomes a thick disk shape, and the degree of filling becomes higher in the lower layer. This is the preferred shape for increasing accuracy.

Normally, in the case of sand filtration, if the suspended particles have a large diameter and the filtration rate is high, a stable adhesion state cannot be maintained after the particles come into contact with the filter medium. In other words, this indicates that the adhesion efficiency decreases due to the scattering of captured SS, but in the case of fiber lumps, it is confirmed that the removal efficiency remains constant with respect to changes in the filtration rate.

The reason for this is that the fiber mass is composed of fibers and has elasticity, and as mentioned above, when the filtration rate increases, the water pressure compresses the filter medium layer slightly, increasing the degree of filling. This is thought to be due to the fact that the penetration of SS is suppressed, and this compensates for the deterioration of the adhesion effect when the filtration rate is high. On the other hand, unlike in the case of sand filtration, the surface of the packed bed 8 is not flat, but rather has a very uneven surface. Because the layer is formed unevenly and its thickness is uneven, an appropriate physical filtration capacity is maintained by expanding the surface area of the layer and mixing thin layer thickness for easy filtration. It is possible to respond to the aspect of ``strong in the field''.

In this case, as a natural structure of a treatment tank, the packed bed 8 is stacked on a support bed 11 made of gravel or the like, and a water collection pipe 12 is arranged in the support bed 11. .

In this case, the air diffuser 13 for backwashing
is arranged at a position slightly below the surface layer of the filling layer 8.

Backwashing performed using the air diffuser 13 will be described in detail below.

In other words, if filtration continues for a predetermined period of time or more,
Eventually, the filtration pressure will increase or the SS will begin to leak. It must be cleaned before reaching this state.

There are two methods for cleaning filter media:

(a) Automatic semi-continuous cleaning by blowing air from the air diffuser 13 for backwashing.

(b) Continuous cleaning in which cleaning water is continuously supplied from the bottom of the filtration layer from the water collecting pipe 12 at the same time as the above air blowing.

The former (a) is advantageous because it requires less water for washing, but in this case, the specific gravity of the filter medium is extremely light.
Only (a) can be sufficiently stirred and the desired cleaning can be performed.

To explain method (a) in detail, first, water flow is stopped, then the water level in the treatment tank is lowered, and then the blower is operated to blow in air from the aeration pipe 13.

This air violently stirs the water in the tank,
The filter medium layer is loosened and dispersed into individual fiber clumps, and is washed by convection in the water flow in the area where the filter medium is stirred.

At this time, the captured SS is completely peeled off from the surface and inside of the filter medium. Excess sludge is allowed to settle and is drawn out by the pump 6 in a timely manner.

In this case, since the specific gravity of the filter medium is light, SS
Washing waste water containing
It is also possible to drain the water out of the system through a permanently installed drain (not shown) at the bottom of the tank.

During this backwashing, the fiber mass does not flow out of the net-like material 10 and enter the upper microbial growth retention area.

There are various ways to determine the timing of backwashing, as described below, and it may be selected depending on conditions such as the characteristics of raw water, the frequency of backwashing, the grade of required water quality, and the maintenance management system.

(b) Method by water quality check.

Water quality of treated water (especially suspended solids concentration, turbidity, etc.)
This is done by measuring regularly or automatically and making a judgment.

(b) Method using treatment tank water level detection.

Since the water level in the treatment tank will rise due to the decrease in filtration capacity, backwashing will begin when the water level rises to a predetermined level.

(c) Method using a timer.

If the situation of backwashing period is clarified by method (a) etc. and the cycle time is known,
Automatic cleaning is possible with a built-in timer.

(d) Method based on water volume detection.

This method takes advantage of the fact that when the filter layer becomes clogged, the instantaneous flow rate of treated water decreases.

(e) Method by detecting cumulative water volume.

The integrated flow rate is detected on the raw water side or the treated water side, and the process is performed at regular flow rate intervals.

The filtration layer formed by the packed bed 8 of the present invention described above has the following characteristics as compared to the conventional sand filtration layer.

(1) Ultra-high-speed filtration is possible.

Since it is filled with a spherical filter medium made of small diameter fibers and has a high porosity, the filtration rate (LV) is 30~30.
Filtration is possible at a rate of 70 m/hr, which allows the installation area of the filtration tank to be small. Since it is possible to secure a predetermined amount of water to be treated by reducing the planar area, layer thickness, and water head, there is no problem even if the area is narrower than the microbial breeding and retention area.

(2) The quality of the filtered water is good.

Raw water (biologically treated water) SS14~
When 28mg/ of water is filtered, the treated water has a SS of 2mg/or less and a transparency of 100cm or more, resulting in good water quality.

(3) Low pressure loss and energy savings.

Since the filtration porosity is large, high speed (LV50
Even with filtration (m/Hr), the pressure loss is as small as 0.06Kg/ ^cm2 , and the pump power is small.

(4) The amount of washing water required is small.

As a washing method, stirring in water using air is sufficiently effective, and the washing water may be used in an amount of 1 to 2% of the filtered water.

(5) It is also possible to perform denitrification.

The purification by the filtration layer of this proposal does not only remove fine suspended solids through physical filtration, but also reduces the LV by 0.1.
5 m/hour, residual organic matter in the wastewater is supplemented and denitrified by the activity of microorganisms attached to the filter medium.

The mechanism of nitrogen removal is in the microbial retention area at the top of the treatment tank, where ammonia nitrogen and organic nitrogen in wastewater are oxidized to nitrite nitrogen and nitrate nitrogen (nitrification).

Next, when passing through the filtration layer, the dissolved oxygen inside the filtration layer is in an anaerobic state with almost zero dissolved oxygen except for air washing, so due to the action of microorganisms, the above-mentioned
NO ₂ -N and NO ₃ -N are converted into gases such as N ₂ (nitrogen gas) and released (denitrification).

In addition, in this case, if the water collection is drawn out by a pump, the layout will be much easier.

The biggest feature of this proposal is that the filtration section 3 is smaller than the aeration section 2.
Since the space is narrow, a space may be formed at the bottom of the aeration section 2, but this can be removed by machines, operating valves,
By using it as a housing section for piping, etc., construction can be carried out even under conditions where space is limited.

That is, as shown in the figure, the pump 14, operating valve 15, piping 16, etc. are all accommodated within the area occupied by the tank 1 at the bottom of the aeration section 2, and do not occupy a separate space.

As a result, an optimal layout has become possible.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the use of space in the conventional device, and FIGS. 2a and 2b are plane and longitudinal cross-sections of the present device. 1... treatment tank, 2... aeration section, 3... filtration section,
4... Diffuser pipe, 5... Raw water pipe, 7... Level controller, 8... Filled bed, 9... Filter medium stirring allowance, 1
0...Network, 11...Support floor, 12...Water collection pipe, 13...Diffuser pipe, 14...Pump, 15...
Operation valve, 16...piping.

Claims (1)

[Scope of utility model registration request] At the bottom of the microorganism breeding and retention area configured in the aeration section for biological treatment of activated sludge, biofilm, etc., a predetermined free space section configured to have a narrower planar area than the aeration section planar area is provided. A filtration tower consisting of a cylindrical or spherical container filled with fiber lumps covered with a mesh material to prevent the filter media from flowing out is connected, and machines, valves, and piping are installed in the space at the bottom of the tank formed by this. What is claimed is: 1. A wastewater treatment device characterized by accommodating a filtration tower, etc., and further having a backwashing pipe arranged inside the filtration tower.