JPH0736917B2 - Organic wastewater biological treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel treatment device for highly purifying organic wastewater such as sewage, various industrial wastewater, septic tank sludge, and human waste.

[Conventional technology]

A conventional aerobic biological filter device is a tank as shown in FIG.
Under the water surface of 21, a packed bed of various granular solids such as anthracite, granular activated carbon, chamotte, etc. (called biological filter bed 22) is provided, and an air diffuser pipe 23 is arranged in the lower part of the biological filter bed 22. is there. A single type of filter medium is used for the filling layer, and a plurality of types of filter medium are not used.

This aerobic filter bed has 24 sedimentation tanks and 2 treated water storage tanks.
8. A washing and drainage storage tank 30 is installed.

In the organic sewage (raw water), after SS which easily settles in the sedimentation basin 24 is separated by sedimentation, the overflowing sedimentation water flows into the upper part of the treatment tank 21 from the pipe 25 and flows through the biological filter bed 22 in a downward flow. In contact with microorganisms on the surface of the granular filter medium and air bubbles supplied from the blower 26, BOD is biologically removed and fine SS is removed by filtration, resulting in clarified treated water and treated water through the outflow pipe 27. It flows into the storage tank 28.

As such operation continues, the trapped SS in the biological filter bed 22
Due to the increase in the amount, the filtration resistance increases and the quality of the treated water also begins to deteriorate.
Is supplied to the lower part of the filter and the biological filter bed 22 is backwashed.

The washing wastewater of the biological filter bed 22 overflows from the upper part of the tank 21 and flows into the washing drainage tank 30, and then is supplied to the sedimentation basin 24 by the pump 31 to separate the SS content from the raw water and the washing drainage flow rate. The total amount is again fed to the submerged filter bed 22.

[Problems to be Solved by the Invention]

However, the conventional device shown in FIG. 2 has the following major drawbacks, and it is the actual situation that a further excellent device and system are desired.

When the raw water SS is high, a sedimentation basin must be installed in front of the aerobic biological filter bed as shown in Fig. 2 to remove the SS and reduce the biological filter bed to an acceptable concentration.

Otherwise, the filter bed of the aerobic biological filter bed will be rapidly clogged (blocked), and it will be impossible to continue the operation of the biological filter bed. The frequency of cleaning the filter bed also increases dramatically. Moreover, since the sedimentation separation speed of the sedimentation pond can be set to only about 30 m / day,
The installation space of the sedimentation pond and the construction cost are large.

SS carryover from the settling pond inevitably occurs when the flow rate fluctuates and flows into the aerobic filter bed,
Speed up the clogging of the filter bed.

Scum is generated in the sedimentation pond, and bad odors such as hydrogen sulfide are also emitted from the surface of the sedimentation pond, resulting in poor appearance and working environment.

Even if a sedimentation basin is installed before the aerobic organism filter bed, the SS removal rate in the sedimentation basin is not high, so the aerobic organism filter bed is clogged quickly and the filter bed should be washed once a day. It must be made. Therefore, the production efficiency of the treated water deteriorates.

The object of the present invention is to completely solve the above-mentioned drawbacks of conventional devices,
It is to achieve organic wastewater extremely effectively and rationally.

[Means for Solving the Problems]

The present invention is directed to a first aerobic immersion filter bed filled with a granular filter medium (filter medium average particle size d ₁ , specific gravity ρ ₁ ), and a granular filter medium (filter medium average particle size disposed on the first filter bed). d ₂ and specific gravity ρ ₂ ) The second aerobic immersion filter bed filled with the second aerobic immersion filter bed, and the inflow port of the organic waste water provided at the lower part of the first filter bed, and the waste water is flowed in an upward flow. A treatment tank for letting treated water flow out from the upper part of the second filter bed, wherein a space is provided between the first filter bed and the second filter bed, and both of the granular filter media are d. This is a biological treatment apparatus for organic wastewater, which is characterized by satisfying the conditions of ₁ > d ₂ and ρ ₁ <ρ ₂ and can solve the above problems.

The present invention is, in an aerobic biological filter treatment apparatus, an aerobic immersion filter apparatus in which two types of granular filter media having different particle sizes and specific gravities are filled in the upper part and the lower part of an integrated treatment tank. It is a device that processes in an upward flow. Granules used for the lower first aerobic immersion filter bed (hereinafter referred to as the first filter bed) and the second upper aerobic immersion filter bed (hereinafter referred to as the second filter bed) By using a granular filter medium (hereinafter referred to as the first filter medium) having a particle size larger than that of the filter medium (hereinafter referred to as the second filter medium) and a specific gravity smaller than that of the second filter medium,
The first filter bed and the second filter bed have different processing functions to improve processing efficiency.

That is, as a function and effect obtained by limiting the particle diameters of the first filter medium and the second filter medium, particularly, the first filter bed is used to pass the waste water.
By having the function of removing BOD and the like by biological oxidation and by using the above-mentioned first filter medium, the packing density can be made smaller than that of the second filter medium, that is, the space between the filter mediums can be made larger, so SS of sewage can be used as the second filter medium. In comparison, it can be captured and held sufficiently. In addition, the second filter bed has a smaller space between the filter media and a higher packing density than the first filter bed, so that minute SS and the like not removed by the first filter bed can be reliably filtered and removed.
BOD etc. can be reliably removed. In addition, since the SS capture is functionally separated by the first filter medium and the second filter medium, and the absolute capture amount is increased, the cleaning frequency can be reduced and BOD etc.
Since the filter bed and the second filter bed are removed in two stages and in an upward flow, the sewage component does not remain on the surface of the second filter bed, and thus it is possible to prevent the malodor from being emitted to the outside of the system.

On the other hand, in the present invention, as the effect of limiting the difference in specific gravity, that is, when the specific gravity ρ ₂ of the second filter medium is larger than the specific gravity ρ ₁ of the first filter medium,
The packing density of the filter media in the first filter bed is smaller than that in the second filter bed, and the voids between the filter particles can be increased.
This can give the same action to the first filter bed and the second filter bed as in the case of limiting the particle size. That is, it means that the amount of SS captured in the first filter bed can be made larger than that in the second filter bed, and the second filter bed can be subjected to strict SS filtration. Furthermore, the specific gravity ρ ₁ of the first filter medium is the second filter medium ρ ₂
Since it is smaller, the first filter medium is easily shaken by the rise of the oxygen-containing bubbles, which has the effect of slowing the progress of SS clogging. On the contrary, since the second filter medium has a large specific gravity, the packing degree becomes dense and the filter medium does not move due to the upward movement of bubbles, so the SS trapping effect is extremely good and the residual SS flowing out from the first filter bed is almost completely trapped. it can.

Further, in the filter bed cleaning for recovering the state where the SS trapping capacity of the device of the present invention is saturated, if the first filter medium has a smaller specific gravity than the second filter medium, the first filter medium is easily stirred and the cleaning effect is obtained. Since it can be higher than the second filter medium, both filter beds can be reasonably washed.

On the other hand, if ρ ₁ > ρ ₂ , the above effect cannot be obtained at all.

Since the second filter medium has a larger specific gravity than the first filter medium, if the first filter bed and the second filter bed are continuously filled, the first and second filter mediums are mixed at the time of cleaning the device of the present invention. It is necessary to prevent this by providing a space in the. Examples of means for providing this space include providing a water-permeable holding member at the bottom of the second filter bed.

The average particle size of the first filter medium used in the present invention is preferably in the range of 4 to 10 mm, and the average particle size of the second filter medium is preferably in the range of 1 to 3 mm. The specific gravity of the first filter medium is 1.2 or less,
The specific gravity of the second filter medium is preferably in the range of 1.5 to 2.5.

The material of the first filter medium and the second filter medium is not particularly limited as long as it is capable of forming a biofilm and has appropriate strength and corrosion resistance, and known inorganic materials such as ceramics, coal and rocks. And the like, and organic materials such as various resins such as plastics can be used.

Preferable examples of the first filter medium include a porous body having a large specific surface area, and chamotte, lightweight aggregate, that is, neolite (trade name; fired anti-fire stone) and the like,
Preferable examples of the second filter medium include granular activated carbon and anthracite.

The biofilm-forming microorganism used in the present invention is not particularly limited, but examples include BOD-oxidizing bacteria, nitrifying bacteria,
Examples thereof include denitrifying bacteria and yeast.

The apparatus of the present invention can use known means for maintaining the first filter bed and the second filter bed under aerobic conditions. For example, an air diffuser for supplying an oxygen-containing gas to the lower part of the first filter bed can be used. It is possible to provide it. Alternatively, a means such as dissolving oxygen in the water to be treated before introducing the water to be treated into the apparatus can be used.

Further, the present apparatus can be provided with an arbitrary processing space having other functions in addition to both filter beds. For example, a space for precipitating and retaining the settling SS of wastewater can be provided under the first filter bed integrally with both filter beds. In this case, the coagulant may be added before introducing the waste water into the space.

In the present invention, the organic sewage is introduced from the inlet at the lower part of the first filter bed, but the introduction means is not particularly limited, and even if it is directly introduced, it is first stored in the sewage storage tank before being introduced. You may.

As a method for washing both filter beds of the device of the present invention, any method can be used without particular limitation.

For example, air may be supplied from the air diffuser to both filter beds, and treated water or raw water may be passed to send the wash water from the upper part of the second filter bed to the waste water storage tank.

The volume ratio of the first filter bed to the second filter bed in the present invention depends on the water quality of the treated raw water, but SS is 50 to 300 mg / l and BOD is 40 to 500 m.
When it is in the range of g / l, the first filter bed: the second filter bed = 1: 0.5 to 2.0, more preferably 1: 1.

In the case of the above water quality, BOD is 20 mg / l or less and SS is 10 mg / l.
The filtration speed for obtaining treated water of 1 or less can be set to 100 to 250 m / day, and the first filtration bed or the second filtration bed of the present invention can be used.
A filtration rate of 4 to 10 times can be achieved as compared with a conventional upflow treatment apparatus comprising a filter bed corresponding to only one of the filter beds.

In this case, in the device of the present invention, the continuous filtration time required for cleaning is about 48 hours, whereas in the conventional device it is about 12 hours, and the present invention achieves a continuous filtration time about 4 times that of the conventional device. it can.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. 1 and the structure and operation of the present invention will be described.

The processing apparatus 1 of the present invention is composed of three main parts when viewed in the height direction. That is, the lowermost portion is composed of three main parts: a settling portion A of SS, an intermediate portion is a first filter bed B filled with a first filter material b, and a second filter bed C is filled with a second filter material c.

2 is organic sewage such as sewage, 3 is a raw water storage tank, 4 is a raw water supply pipe, and 5 is a raw water pump.

The part a which is blackened under the settling part A represents the settled sludge. 6 is a sludge discharge pipe, 7 is an air diffuser for supplying air to the first filter bed B and the second filter bed C, and 8 is air or an oxygen-containing gas.

Further, a space B is provided between the first filter bed B and the second filter bed C. 9a and 9b are porous water-passing members that support the granular filter media of the first filter bed B and the second filter bed C, 11 is a treated water outlet launder, and 12 is a treated water outlet pipe. Further, 13 is a washing drainage outflow pipe, and 14 is a treated water storage tank, which is used when washing the first filter bed B and the second filter bed C. 15 is a cleaning water supply pump.

If necessary, a porous water-permeable member for holding the first filter medium b and the second filter medium c may be provided in the upper portion, and when the specific gravity is 1.0 or less, or close to 1.0, the porous water-permeable member is provided in the upper portion of the filter bed. Set up.

The principle of operation of the present invention will be described.

Organic sewage (raw water) such as sewage flows into the settling section A from the raw water inflow pipe 4, and SS that easily settles is settled and separated.

The colloid and fine SS in the raw water may be flocculated by adding the flocculant 16, and the flocs may be separated at the precipitation portion A.

The raw water from which most of the sedimentable SS has been precipitated and separated becomes an upward flow and first enters the first filter bed B.

On the surface of the first filter medium b, a biofilm that consumes the BOD component in the raw water is propagated by the oxygen supplied from the air bubbles, and in the process of the raw water passing through the first filter bed B, BOD Are biologically removed, while at the same time fine SS is filtered off.

Then, after passing through the space b, SS and BOD that flowed into the second filter bed C and could not be completely removed in the first filter bed B were highly removed in the second filter bed C, and were clearer than the water surface. Treated water 10 flows out.

In the present invention, by setting the particle size of the second filter medium c smaller than the particle size of the first filter medium b and making the specific gravity of the second filter medium c larger than the specific gravity of the first filter medium b, the second filter bed is obtained. Of C
It is possible to enhance the filtration effect of SS, and moreover, since the voids between the filter media of the first filter bed B can be maintained large, there is an advantage that the trapping capacity of SS is large and the increase of filtration resistance can be reduced.

In addition, it is necessary to provide a space b between the first filter bed B and the second filter bed C in order to prevent mixing of the first filter material b and the second filter material c in each filter bed. Since the specific gravity of the second filter medium c is larger than that of the first filter medium b, unless the space b is provided, the filter mediums b and c will be mixed during the cleaning of the filter bed, resulting in a treatment effect. Cause deterioration.

In a preferred embodiment of the particle sizes of the first filter medium b and the second filter medium c, the particle size of the first filter medium b is 4 to 10 mm, and the particle size of the second filter medium c is 1 to 3 mm. Further, it is suitable that the layer thickness of the first filter bed B is 1 to 2 m, and the layer thickness of the second filter bed C is 0.5 to 1.5 m.

The space b is also important for allowing the filter medium to expand when the first filter medium b is backwashed.

With the above operation, as the operation is continued for a long time, the amount of SS captured in the first filter bed B and the second filter bed C reaches the limit, which causes a significant increase in the filtration resistance. Wash bed B and second filter bed C.

The washing of the first filter bed B and the second filter bed C is preferably performed by the following method.

The treated water valve 18 is closed, the washing and draining valve 19 is opened, and the inflow of the raw water 3 into the settling portion A is stopped to increase the amount of air from the air diffuser member 5 to 10 times as much as in the steady operation. A violent rising bubble flow is generated in the first filter bed B and the second filter bed C.

The washing pump 15 is driven to give a strong rising water flow to the first filter bed B and the second filter bed C to expand and fluidize these, and the SS trapped in the filter bed is washed out by the rising bubbles and the rising water flow. The cleaning drainage is introduced into the raw water storage tank 3 via the cleaning drainage pipe 13. (Note that the cleaning drainage tank may be separately provided and the cleaning drainage may flow into this.) After the above operation is continued for a predetermined time (about 5 to 10 minutes), the supply of the air 8 and the cleaning water 17 is stopped.

The cleaning drain valve 19 is closed, the treated water valve 18a is opened, and the raw water 4
Is restarted and the diffused air 8 is set to a steady amount.

The above is a preferred example of the method for cleaning the first filter bed B and the second filter bed C in the present invention.

According to the experiment of the present inventor, in the case of sewage treatment, the amount of air 8 to be diffused is ^1-2 QNm ² / day when the sewage treatment amount is Qm ² / day during the steady treatment. It was only 1/5 to 1/7 of the required air volume for the activated sludge method, and it was confirmed to be extremely energy-saving.

In addition, the recovery of the treated water quality after washing the filter bed is fast, and after 20 to 30 minutes, clear treated water of SS 10 to 15 mg / l is obtained.

In the present invention, the effect of improving the quality of treated water by providing the second filter bed C on the first filter bed B is remarkable, and is simply the first filter bed.
It was also confirmed that even if the layer thickness of the filter bed B was increased, good treated water with low SS could not be obtained.

If the first filter bed B is omitted and only the second filter bed C is used,
The drawback was that the filter bed became clogged quickly and required frequent washing.

As a result of various studies by the present inventor on the types of filter media of the first filter bed B and the second filter bed C, the first filter material b is a lightweight aggregate (particle diameter 8 mm) having a specific gravity of 1.1 to 1.2, and the second filter material c is Is an anthracite with a specific gravity of 1.5 (particle size 3 mm), which allows a long filtration duration,
It was confirmed that the quality of water and treated water would be good.

〔The invention's effect〕

According to the present invention as described above, it was confirmed that the following important effects can be obtained.

The extremely clear treated water flows out from the upper part of the treatment tank like a fountain, so it has a very beautiful appearance and no odor is generated.

 No SS carryover or scum occurs.

As a result of the multi-layered structure of the first filter bed and the second filter bed, even if the filtration rate is high, the clogging progress rate of the filter bed is low, and in the case of sewage treatment, ultra-high-speed treatment of 250 m / day is possible and filtration is continued. The time was 48 hours.

When treating sewage with the conventional equipment shown in Fig. 2, the rising velocity of the sedimentation basin is only 30 m / day, the filtration rate of the aerobic biological filter is 25 m / day, and the continuous filtration time of the biological filter is 12 ~. It is clear how the present invention can achieve high performance as compared with what was possible only for about 15 hours.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention. FIG. 2 is a diagram for explaining a conventional device. DESCRIPTION OF SYMBOLS A: settling part, B: first filter bed C: second filter bed, b: first filter material c: second filter material, a: sludge, b: space part, 1: treatment device of the present invention 2: organic Sewage, 3: Raw water storage tank 4: Raw water supply pipe, 5: Raw water pump 6: Mud pipe, 7: Diffusing member 8: Air or oxygen-containing gas 9a, 9b: Porous water passing member, 10: Treated water 11: Treated water outflow launder 12: Treated water outflow pipe, 13: Wash drainage outflow pipe 14: Treated water storage tank, 15: Wash water supply pump 16: Flocculant, 17: Wash water 18, 18a: Treated water valve, 19: Wash Drain valve

Claims (1)

[Claims] 1. A first aerobic immersion filter bed filled with a granular filter medium (average particle size of filter medium d ₁ , specific gravity ρ ₁ ), and granular filter medium (average particle size of filter medium disposed on the first filter bed). A _second aerobic immersion filter bed filled with a diameter d ₂ and a specific gravity ρ ₂ ) and an inlet port for organic waste water provided at the lower part of the first filter bed are used to pass the waste water through an upward flow. A treatment tank for allowing treated water to flow out from the upper part of the second filter bed, wherein a space is provided between the first filter bed and the second filter bed, and both of the granular filter media are d ₁ ＞ d ₂
And a biological treatment apparatus for organic sewage, which satisfies the condition of ρ ₁ <ρ ₂ .