JP2584763B2 - Immersion filter bed method for cleaning biological treatment equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cleaning a biological treatment apparatus using a immersion filter bed method for biologically treating water to be treated containing an organic substance and / or a nitrogen component. It is.

<Conventional technology> Conventionally, organic substances (BOD) contained in treated water such as wastewater
Or removal of COD), or nitrogen components (NH ₄ -N, NO ₃ -
As a biological treatment apparatus for performing nitrification or denitrification of N, etc., a immersion filter bed treatment apparatus (hereinafter referred to as an immersion filter bed apparatus) that is easily operated and can obtain an arbitrary removal rate is widely used. ing. The immersion filter bed apparatus flows in the water to be treated containing an organic substance and / or a nitrogen component from the upper or lower part of a filler layer composed of gravel, crushed stone, Raschig rings, a net-like body, and the like, and microorganisms that have formed on the filler layer ( Aerobic microorganisms or anaerobic microorganisms) to biologically decompose and remove organic matter in the water to be treated or to biologically nitrify or denitrify nitrogen components, so-called free biological treatment Compared to the apparatus, the concentration of microorganisms in the tank can be considerably increased, and therefore, it has the feature that high-load treatment of organic substances or nitrogen components is possible.

However, in such a submerged filter bed apparatus,
If the treatment of the treated water is continued, the filler layer will be clogged due to the enlargement of microorganisms and the accumulation of suspended solids in the treated water, and it will not be possible to secure a predetermined water flow rate. So-called washing, in which washing water and / or washing gas flows periodically from the lower part of the filler layer to eliminate clogging of the filler layer, since the anaerobicization of microorganisms and the quality of treated water deteriorates. You are performing an operation.

<Problems to be Solved by the Invention> When cleaning the filler layer in such a immersed filter bed apparatus, if the cleaning effect is to be enhanced, the filler layer is fluidized smoothly during cleaning, and the fillers are mutually separated. It is necessary to separate them. However, in the conventional immersion filter apparatus, natural fillers such as natural gravel or crushed stone are used as fillers, and large fillers are used to prevent clogging.
In most cases, a filler is used, so that a relatively large flow rate of water and / or air is required to fluidize the filler layer, and thus a large power is required. And the disadvantage that the cleaning effect is often insufficient. Further, when washing is performed using water and / or air having such a large flow rate, excessive separation of microorganisms that have formed on the surface of the filler occurs, and the treated water quality in the water passage treatment immediately after washing is reduced. There is also the problem that it worsens temporarily.

The present invention solves such a problem in a conventional immersion filter bed apparatus, and can reduce the power required for cleaning when the filler layer is clogged, and can reduce the power required for water passing treatment immediately after cleaning. It is an object of the present invention to provide a method for cleaning a submerged filter bed apparatus that can prevent temporary deterioration of treated water quality as much as possible and stabilize treated water quality.

<Means for solving the problems> The present invention forms a filler tank by filling a tank with an aerobic microorganism or an anaerobic microorganism grown on its surface to form a filler tank, and as the filler, The specific gravity of floating above the treated water to form a floating filler layer is 0.9 or more and less than 1.0, and the specific gravity of sedimenting in the treated water to form a settling filler layer is 1.0 or more and 1.1 or less. The two kinds of particulate matter are filled so as to form a space between the two filler layers for fluidizing the filler during washing, and the water to be treated flows into the filler layer to remove the water to be treated. In biological treatment equipment using a immersion filter bed method for biological treatment, microbial enlargement is severe and clogging is frequently caused.Partial washing to fluidize only one filler layer, and both filler layers are clogged. And selecting the whole cleaning to fluidize the entire filler layer in the event of occurrence of A.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

The drawing is an immersion filter bed apparatus using aerobic microorganisms, and is a longitudinal sectional explanatory view showing an example in which the present invention is applied to an apparatus configured to allow water to be treated to flow upward in a filler layer. A floor plate 2 having a large number of openings or slits is provided below a tank 1 having a circular or rectangular cross section, and a plurality of collectors (water collecting mechanisms) 3 having a large number of slits are provided above the tank 1. The filling material 4 is filled in the tank 1 between the floor plate 2 and the collector 3. The filler 4 is a mixture of two types of particulates, which float in the water to be treated and have a specific gravity of 0.9 or more and less than 1.0, and those which sink in the water to be treated and have a specific gravity of 1.0 or more and 1.1 or less. As shown in the drawing, a floating filler layer 5 composed of a filler 4A floating in water and a settling filler layer 6 composed of a filler 4B settling in water as shown in the drawing.
To form In addition, a space 7 between the two filler layers 5 and 6 is provided such that the filler 4 can flow smoothly when washing is performed.
Is provided. In the following description, the entirety of the floating filler layer 5, the settling filler layer 6, and the empty space 7 will be collectively referred to as a packed layer portion 8. In addition, a plurality of water diffusion pipes 11 having a large number of holes communicating with the raw water pipe 9 and the washing water pipe 10 and a large number of air diffusion pipes 13 having a large number of holes communicating with the air pipe 12 are buried under the floor plate 2, respectively. Further, an outlet pipe 14 is connected to the collector 3.

The filler 4 used in the present invention is, for example, a granulated and baked porous artificial stone or a granulated brick that has been granulated and baked by adjusting the specific gravity of natural stone or granulated by calcining natural stone, It is desirable to use one having a particle size of about 15 to 30 mm. The shape of the filler 4 is not particularly limited as long as it is a granular material. However, in order to maintain an appropriate porosity between the fillers 4 and to perform a smooth flow of the filler 4 during washing, the shape of the filler 4 is substantially spherical. In order to reduce clogging, it is desirable that the surface has a smooth surface and no irregularities.

<Effect> In order to treat the water to be treated containing, for example, organic substances or NH ₄ —N by the immersion filter bed apparatus shown in the drawing, the raw water pipe 9
The water to be treated flows through the hole of the water sprinkling pipe 11 through the through hole, and the water to be treated flows through the packed bed portion 8 in an upward flow, and the air pipe
Air flows in from the hole of the air diffuser 13 through 12. In this manner, the biological oxidation and decomposition of organic substances in the water to be treated or the biological nitrification of NH ₄ —N are performed by the action of the aerobic microorganisms that have settled on the settling filler layer 5 and the floating filler layer 6. The treated water is collected from the slit of the collector 3 and can be obtained from the outlet pipe 14. Note that, instead of the collector-3, a holding plate (for example, a wire mesh) having a large number of openings is horizontally provided in the tank 1 and an outlet pipe is provided above the holding plate.
14 may be provided.

While such treatment is continued, the packed bed portion 8 is enlarged due to the enlargement of aerobic microorganisms and the slight accumulation of SS in the water to be treated.
Are clogged, so that they are periodically cleaned. In the present invention, the cleaning is performed by partially cleaning the packed bed portion 8 under relatively mild cleaning conditions (hereinafter referred to as normal cleaning),
Clogging of the packed bed portion 8 is effectively eliminated by performing two types of washing with the entire packed bed portion 8 (hereinafter referred to as special washing) performed under relatively intense washing conditions. At the same time, it is possible to prevent temporary deterioration of the treated water quality in the water passing treatment after the washing as much as possible.

That is, the enlargement of the microorganisms in the immersion filter bed device,
Filler layer on the side where the water to be treated flows in, tank 1 in the drawing
Violently in the settling filler layer 6 formed in the lower part, while on the outflow side, in the drawing, the floating filler layer 5 in the upper part of the tank 1
Inside, there is a characteristic that the rate of enlargement is slow. Therefore,
In the normal cleaning, after the water supply process is interrupted, the cleaning water flows from the sprinkling pipe 11 through the cleaning water pipe 10 into the packed bed portion 8 at a flow rate of about 3 to 6 times the flow rate in the normal processing. On the other hand, air is introduced from the air diffuser 13 through the air pipe 12 at the same flow rate as during normal processing, and washing is performed for 5 to 20 minutes. At this time, the enlargement of microorganisms in the lower part of the tank 1 is remarkable. The settling filler layer 6 is mainly washed. This is the aforementioned normal cleaning. At this time, the filler 4B forming the settling filler layer 6
As described above, the specific gravity is 1.0 or more and 1.1 or less, close to the specific gravity of the water in the tank 1, easily floated by the rising particles of the washing water and the air, and the filler 4B is separated from the sedimentary filler layer. 6 causes a gentle flow. Excessive aerobic microorganisms that have settled on the surface of the filler 4B due to slight collision between the fillers 4B due to the flow can be separated, and the separated microorganisms are expelled above the settled filler layer 6, and Material layer 6
Most of the clogging is eliminated. Furthermore, the separated microorganisms are finely crushed by the mixed flow of the air and the washing water and rise in the tank 1, and reach the floating filler layer 5 or the filler 4A forming the filler layer 5 As described above, since a relatively large particle having a particle size of about 15 to 30 mm is used, the exfoliated microorganisms are partially captured by the filler layer 5, but most of the microorganisms pass through the gap of the filler layer 5. After passing through, it reaches the collector 3 and is discharged out of the system via the outlet pipe 14. Therefore, the floating filler layer 5 does not suddenly become clogged by the washing.

At this time, the filler 4A that floats in the water to be treated and forms the floating filler layer 5 hardly flows due to its buoyancy, and the microorganisms that have settled on the filler 4A hardly peel off. Therefore, compared to the conventional immersion filter apparatus in which the entire filler layer is fluidized and washed, the amount of microorganisms in the tank after washing can be maintained higher, and thus the quality of the treated water in the water treatment immediately after washing can be maintained. Temporary deterioration can be prevented.

By performing the regular cleaning as described above at regular intervals, it is possible to eliminate clogging of the settling filler layer 6 in which the microbial growth is intense and, therefore, clogging is likely to occur. During the repetition of the above, the microbial enlargement progresses also in the floating filler layer 5 formed in the upper part of the tank 1, and a part of the microorganisms separated by the normal washing is captured in the floating filler layer 5. As a result, the floating filler layer 5 will eventually be clogged. Therefore, in this case, a cleaning method for fluidizing the entire packed bed portion 8,
That is, the above-described special cleaning is performed. The special cleaning is most effectively performed by the following method. That is, after the water supply process is interrupted, first, only the cleaning air flows from the air diffuser 13 through the air pipe 12 at a flow rate about 3 to 6 times that of the normal processing for 3 to 15 minutes, and the rising flow of the cleaning air is increased. By
The fillers 4B settled in the tank 1 are separated from each other and the settled filler layer 6 is fluidized. At this time, in the present invention, the floating filler layer 5 is also fluidized by the rising flow of the cleaning air. Can be done. That is, a circulating flow is generated in the tank 1 by an air lift effect caused by the rising flow of the cleaning air, and a downward flow acts on the floating filler layer 5, while forming the floating filler layer 5 The filling material 4A, which floats in the water to be treated, has a specific gravity of 0.9 or more and less than 1.0, is close to the specific gravity of water in the tank 1, and has not so large buoyancy. By the flow, the floating filler layer 5 can be easily fluidized. If the specific gravity of the filler 4A is less than 0.9, the buoyancy is too large and it is difficult to fluidize by the area soft effect, which is not preferable.

By cleaning only the cleaning air, both the filler layers 5 and 6 are removed.
And cause the fillers 4 to collide with each other,
Some of the SS deposited between the fillers 4 is floated, and excess aerobic microorganisms that have settled on the surface of the fillers 4 are peeled off. Next, with the washing air flowing in or after stopping the inflow of the washing air, the washing air flows again from the air diffuser 13, and at the same time, the washing water is sprayed through the washing water pipe 10.
11 flows at a flow rate of about 3 to 6 times that of the normal processing, and the cleaning by simultaneous inflow of the cleaning air and the cleaning water is performed for 5 to 20 minutes, and the rising flow of the mixed fluid is the same as the case of only the cleaning air. In addition to the above action, the suspended SS and the separated microorganisms are expelled from the packed bed portion 8 by the inflow of the washing water, and are discharged from the outlet pipe 14 through the collector 3 to the outside of the system. As described above, in the special cleaning, by first providing a cleaning step using only the cleaning air, and then providing a cleaning step using the cleaning air and the cleaning water together, some of the SS deposited between the fillers 4 is floated, 4. Exfoliation of surplus aerobic microorganisms from the surface of No. 4 and elimination of SS and aerobic microorganisms from the packed bed portion 8 can be performed effectively.
Further, by providing the cleaning step using only the cleaning air, it is possible to significantly reduce the cleaning water. In addition, in the special washing, before washing with the washing air alone, the water in the tank 1 is drawn in advance by a drain pipe (not shown) attached to the lower part of the tank 1, and the water level is settled and filled. The water level is lowered to a position slightly lower than the upper surface of the material layer 6, and then the washing water flows in from the sprinkling pipe 11 to raise the water level in the tank 1 again to the position of the collector 3, and then the washing air alone is washed. In this case, more effective cleaning can be performed. That is, the floating filler layer 5 follows the vertical movement of the water level in the tank 1.
Also moves up and down by a distance corresponding to the space 7, during which the floating filler layer 5 is loosened, and the filler 4A forming the layer 5
Can be separated from each other.

In the special cleaning, since the entire packed bed portion 8 is fluidized and washed, the aerobic microorganisms settled on the surface of the filler 4 may be excessively peeled off as described above. Although the treated water quality may be temporarily deteriorated in the present invention, in the present invention, the above-mentioned normal cleaning is usually performed with little deterioration of the treated water quality immediately after the cleaning, and after repeating this several times, the special cleaning is performed. It is only necessary to perform once, so that the quality of treated water can be remarkably stabilized, and the energy required for cleaning can be greatly improved as compared with the conventional immersion filter apparatus requiring the same strong cleaning as the special cleaning every time. Can be reduced than before.

Filler 4 used in the present invention floats in the water to be treated and has a specific gravity of 0.9 or more and less than 1.0 (filler 4A)
And those that settle in the water to be treated and have a specific gravity of 1.0 or more and 1.1 or less (filler 4B), and even those that float in the water to be treated and have a specific gravity of less than 0.9, As described above, the buoyancy is too large to fluidize at the time of washing, and even if it settles, those having a specific gravity of more than 1.1 are too heavy and also require large power to fluidize. Absent. The respective fillers 4A and 4B to be mixed may be any as long as the above conditions are satisfied, and may be a single specific gravity, or may have a specific specific width. .

In addition, the mixing ratio of the filler 4A floating in the water to be treated and the filler 4B sinking in the water to be treated is 30 to 70% of those floating in the water to be treated, and 70% of those floating in the water to be treated. ~ 30
%, And preferably each filler is mixed in half and filled. By using such a mixing ratio, it is possible to obtain an immersion filter bed device capable of effectively cleaning the filler layer and reducing the temporary deterioration of the treated water quality in the water passing treatment immediately after the cleaning as much as possible. .

In the above-described embodiment, the configuration is such that the water to be treated flows through the filler layer in the upward flow, but the present invention may be configured to flow the water to be treated in the downward flow.

As described above, an example in which the present invention is applied to a immersion filter bed apparatus using an aerobic microorganism has been described.However, even when the present invention is applied to an immersion filter bed apparatus using an anaerobic microorganism, for example, an anaerobic fermentation apparatus, a tank is used. The gas generated by closing the upper part of 1 is collected, and the collected gas flows in through the hole of the air diffuser 13 instead of air. Description is omitted.

<Effects> As described above, in the present invention, as a filler of the immersion filter bed device, a material that floats in the water to be treated and has a specific gravity of 0.9 or more and less than 1.0, and a material that sediments in the water to be treated and has a specific gravity of 0.9 or less.
1.0 or more and 1.1 or less, both of which use a filler mixture of two types of particulate matter close to the specific gravity of the water in the tank, so in cleaning, water or air for fluidizing the filler is used. Low flow rate and energy saving.
Furthermore, since the filler forms a floating filler layer and a sedimentary filler layer separately in the tank, in normal cleaning, microorganisms are greatly enlarged on the side to which the water to be treated flows, and the frequency of clogging is severe. Cleaning can be performed by selectively fluidizing only one of the filler layers, and only when the cleaning is repeated and both filler layers are clogged. Therefore, it is possible to maintain a high level of microorganisms in the tank, because the degree of exfoliation of epiphytic microorganisms is less than that of conventional equipment, in which the entire filler layer must be strongly washed every time washing is performed. Therefore, it is possible to prevent the temporary deterioration of the treated water quality in the water passing treatment immediately after washing as much as possible, and to stabilize the treated water quality dramatically.

<Examples> Examples will be described below to clarify the effects of the present invention.

Made of almost spherical artificial stone with a particle size of 15 to 30 mm, specific gravity 0.95
And a granular material having a specific gravity of 1.05 mixed in halves was used as a filler, and the actual packed bed height (layer height of the filler alone excluding the void 7 in the drawing) was 3.4 m. A immersion filter bed apparatus A (example of the present invention) as shown in the drawing, with a particle size of 15 to
Using artificial stone with 30 mm and specific gravity of 1.5 as filler, and using a dipping filter bed apparatus B (conventional example) with a filler layer height of 3.4 m, while periodically performing cleaning under the following conditions, respectively. The aerobic treatment of food processing wastewater was continuously performed, and the COD removal performance of both devices in a steady state was compared.

Washing conditions (1) Immersion filter bed device A (Example of the present invention) Normal washing: once a day for 20 minutes Special washing: once a day (process of washing air alone: 10 minutes, washing air and washing water combined use) (Step: 20 minutes) (2) Immersion filter bed apparatus B (conventional example) The same washing as the above-mentioned special washing is performed once a day. As a result, in the immersion filter bed apparatus A which is an example of the present invention, water is passed immediately after the special washing. Degradation of processing performance was observed in the processing (COD removal rate of 50-60%), but in other cases, the performance of COD removal rate of 70-80% was obtained stably, and the clogging of the filler layer was sufficient Had been resolved. On the other hand, in the immersion filter bed apparatus B, the COD removal rate during the normal treatment is 60-70.
%, While the COD removal rate dropped to 40 to 50% every time when water was passed immediately after washing, and at the same time the clogging during washing was somewhat inadequate. There is a tendency to be somewhat clogged, so that the COD removal ability itself during normal processing is also lower than that of the present invention as described above.

[Brief description of the drawings]

The drawing is an explanatory longitudinal sectional view showing an example in which the present invention is applied to a immersion filter bed device using an aerobic microorganism. DESCRIPTION OF SYMBOLS 1 ... Tank, 2 ... Floor plate 3 ... Collector, 4 ... Filler 5 ... Floating filler layer, 6 ... Settling filler layer 7 ... Vacancy, 8 ... Filling layer part 9 ... Original Water pipe, 10 ... Cleaning water pipe 11 ... Sprinkling pipe, 12 ... Air pipe 13 ... Diffusion pipe, 14 ... Outlet pipe

Claims (1)

(57) [Claims] A microorganism fills a tank with a filler that has settled on its surface to form a filler layer, and as the filler, a specific gravity for floating in the water to be treated to form a floating filler layer. Is 0.9
Above, less than 1.0, and two types of particulate matter, the specific gravity of which is settled in the treated water to form a settling filler layer is 1.0 or more, 1.1 or less, between the two filler layers when washing Filling to form a space for fluidization of the filler, in the immersion filter bed biological treatment apparatus for biologically treating the water to be treated by flowing the water to be treated into the filler layer, Partial washing to fluidize one of the packing layers, mainly due to microbial enlargement and high frequency of clogging, and total washing to fluidize the entire packing layer when both packing layers are clogged And a method for cleaning a biological treatment apparatus using a immersion filter bed method.