JPH0741251B2 - Sewage purification device - Google Patents

Description

Description: TECHNICAL FIELD The present invention highly purifies sewage, especially sewage, primary and secondary treated water of human waste, dairy wastewater from domestic sewage, etc. or dairy wastewater from pig farms, etc., using soil. To improve the soil purification device.

[Technical background]

The soil purification method purifies sewage by actively utilizing the adsorption function of digestion and decomposition of soil animals and soil microorganisms yesterday and soil colloids. Therefore, SS content, BOD, CO
Not only can D components, ammonia and other organic substances be adsorbed and decomposed and removed, but also phosphorus and nitrogen, which are difficult to remove by the widely used sprinkling filter method and domestic sludge method, can be easily removed and deodorized, as well as energy saving. The cost is excellent.

However, conventional soil purification methods are not completely ideal. This is because although the various conditions required for soil are inconsistent as it is an ideal sewage purification method, those conditions have not been sufficiently considered or examined. Therefore, as a result of earnest studies, the present inventor has found that the properties required for the soil used in the soil purifying apparatus can be summarized in the following three points.

The water permeability is high enough that clogging is unlikely to occur. This determines the wastewater treatment capacity. It is an important property from the viewpoint of effective use of land.

High content of compounds capable of adsorbing phosphoric acid such as activated aluminum and activated iron. This determines the ability to remove phosphorus from wastewater.

The aerobic soil layer required for nitrification and nitrite of ammonia nitrogen and the carbon layer required for the denitrification by microorganisms, and the relatively anaerobic soil layer coexist, and It must have a structure that can pass through both layers at a sufficient speed and can sufficiently contact and penetrate both layers. This determines not only the decomposition and purification of pollutants in wastewater, but also the nitrogen removal capacity in wastewater.

The inventors of the present invention are able to satisfy both of these contradictory conditions, and the soil layer having excellent air permeability and water permeability (hereinafter referred to as "water permeable / aerobic soil layer") and the air permeability / water permeability are inferior. An ideal soil remediation method and device, which should be called a multi-stage soil layer method, has been developed that combines active aluminum, daily iron, and a soil layer rich in carbon sources (hereinafter referred to as "impermeable and anaerobic soil layer") ( Japanese Patent Application No. 60-52729).

The device (a) shown in FIG. 9 is an example of such a device. Below the sewage sprinkling pipe (3) arranged in a covered soil layer (2) made of masa soil, a non-permeable and anaerobic soil made of black soil is used. Group (b)
A layer comprising a permeable / aerobic soil group (C) consisting of Masa soil and a permeable / aerobic soil layer (D) consisting of Masa soil, provided with a purification layer (E) alternately stacked. Is. In this way, the sewage sufficiently contacts and infiltrates the hardly permeable / anaerobic soil group (b) while flowing down. In addition, various structures are possible such as stacking a poorly permeable / anaerobic soil layer and a water / aerobic soil layer in steps. Water permeability
Zeolites, etc. are used as aerobic soil, and red soil, etc. are used as poorly permeable and anaerobic soils. It is possible to make a purification device according to the amount and nature of wastewater.

[Disadvantages of conventional technology]

The feature of the above-mentioned apparatus based on the multi-stage soil layer method is that, in other words, it is difficult to exert the intended effect unless it is constructed as designed. However, in the actual construction, even if it has a simple structure as shown in Fig. 9, each soil group (b) and (c) is incorporated in a mosaic pattern in one horizontal layer, so the construction is extremely troublesome. . Further, it is practically difficult to finish the layer thickness and area as designed, and the layer thickness and water permeability also change depending on the degree of compaction. Moreover, the predetermined effect does not occur in the area where the soils of both species are mixed.

[Means for solving problems]

The present invention has been made in view of the above, and the amount of soil required to form one layer or group according to the design is packed in a water-permeable container or bag in advance, and these are arranged or stacked. This makes it possible to easily construct a sewage purification device by the multi-stage soil layer method.

And one way of thinking is to pack only the hardly water-permeable / anaerobic soil into a container or bag, and to put this kind of soil block into the water-permeable / anaerobic soil.
It is interposed between aerobic soil layers to form a purification layer. Another approach is to lay / stack blocks of permeable / anaerobic soil and blocks of permeable / aerobic soil at predetermined positions with appropriate intervals, leaving the voids as they are or permeable / aerobic soil. To form a purification layer. If a material having a high carbon ratio (C / N ratio) is used as the material for these containers and bags, denitrification is favorably performed.

The present invention will be described in detail below based on the embodiments shown in the drawings.

〔Constitution〕

(First Embodiment) FIGS. 1 and 2 show an example of a sewage purification apparatus according to the present invention. This sewage purification device (1) has the same structure as the device (a) shown in FIG. 9, and has a water-impermeable / anaerobic soil group (b) ...
Instead of the above, a soil block (6) in which a water-impermeable bag (4) is filled with hardly water-permeable / anaerobic soil (5) is used. The illustrated device (1) (same as (a)) is of a practical scale, and each soil is stored in an iron tank (7) of 75 cm in width, 150 cm in length, and 150 cm in depth with an inner size. Is. And the upper part thereof is a covered soil layer (2) provided with a drainage pipe (3),
The central part is a purification layer (8) and the lower part is a drainage layer (9). Incidentally, nitrification and other reactions also take place in the coated soil layer (2), but the main reaction takes place in the central part, so the central part is defined as the purification layer (8) in the present invention.

The covered soil layer (2) consists of permeable and aerobic soil (masa soil) with a thickness of about 40 cm. The circumference of the water sprinkling pipe (3) is surrounded by a gravel layer (10), the upper surface of the gravel layer (10) is surrounded by a mesh body (11) for preventing clogging, and the lower surface is surrounded by a partition plate (12) for diffusing sewage. And constitutes the trench (13) as a whole. The partition plate (12) improves the dispersion of sewage, and a molded product of plastic or rubber or a flexible sheet is preferably used. The drainage layer (9) is composed of a gravel layer (14) having a thickness of about 15 cm, and a drainage pipe (15) (corrugated pipe, etc.) having a hole is arranged at the bottom. The upper surface of the gravel layer (14) is covered with the mesh body (16),
The upper side is in contact with the purification layer (8) through the sand layer (17) having a thickness of about 5 cm.

On the other hand, the purification layer (8) is composed of the soil block (6) and the permeable / aerobic soil (18). Soil block (6)
15 x 30 (and 20) x 75 cm size jute bag (4)
Is filled with 22 kg (and 15 kg) of black soil, which are arranged with a 10 cm gap. Then, the gap is filled with Masa soil as permeable / aerobic soil (18) to form one layer, and the permeable / aerobic soil (1
8) As a layer of masa soil. Each of these layers (4 layers and 3
Layers) are staggered to make a total of about 90 cm. The soil blocks (6) of each layer are arranged 10 cm apart so that the sewage can sufficiently contact and permeate into the impermeable and anaerobic soil (5). It should be noted that each of the above numbers is an example, and the present invention is not limited to these.

(Action) Then, the sewage (A) that permeates the gravel layer (10) and the covered soil layer (2) from the sewage sprinkling pipe (3) is caused by the digestive decomposition action of soil organisms and the adsorption and filtration action of soil, SS minutes, BOD and COD
It is subject to aerobic decomposition and removal of organic matter and other organic substances. Ammonia nitrogen is also nitrified or nitrated by the action of nitrifying bacteria and the like, and becomes treated water (B). This is the conventional soil purification method (capillary purification method).

A part of the treated water (B) evaporates from the surface of the coated soil layer (2), but most of the treated water (B) gravitationally permeates into the purification layer (8) below the trench (13). At this time, treated water (B)
Is placed under more oxidative conditions mainly through the permeable and aerobic soil (18) (solid arrow).

On the other hand, soil blocks (6) are connected to the top, bottom, left and right of the permeable / aerobic soil (18). The jute bag (4) which is the outer wall of the soil block (6) not only constitutes a unit for filling black soil, but also
As such, it is a reticulate body that exists at the interface between Masa soil and Kuroboku soil, and allows water to permeate and move in all directions at the contact interface between both layers. This bag (4) can be compared to a huge cell wall, and the treated water (B) freely permeates into the Masa sand bag (4) Kuroboku soil as if it freely moves through the plant tissue. Move (dotted arrow). Since the jute bag (4) has an extremely high carbon ratio (C / N ratio) (usually 50 or more), it also serves as a carbon source for denitrifying bacteria and also serves to enhance the denitrifying activity of the device.

At this degree, the phosphoric acid (positive and poly) in the treated water (B) is easily adsorbed and fixed to the black soil in the soil block (6). Further, NO ₂ and NO ₃ in the treated water (B) are also converted to N ₂ and N ₂ O by the action of denitrifying bacteria in the black soil, and are denitrified. Various heavy metals are also adsorbed and removed.

Thus, the purified water (C) from which SS, BOD, COD, and other organic substances, as well as nitrogen and phosphorus are almost completely removed, is discharged out of the apparatus through the drain pipe (15).

(Modification) By the way, in consideration of water permeability, the bag body (4) is preferably a knitted woven fabric having coarse mesh. Further, the material is not limited to jute (linen), and rice straw, coconut fiber, and other natural fiber having a high C / N ratio are preferably used. However, plastic products such as split yarn of plastic film can also be used. However, in that case, it is preferable to mix the carbon source into the filled soil.

As the impervious water / anaerobic soil (5), in addition to the above black soil, red-yellow soil, brown / yellow-brown forest soil or gray lowland soil, etc., active aluminum or active iron is 1 to 2% by weight.
(Available for dry soil) You can use as long as it contains the above.
In some cases, in order to increase the active aluminum content, the soil filled with the active aluminum-containing material may be mixed and used. Further, as the carbon source, leaves and other animals and plants, surplus activated sludge, and other substances having a high carbon ratio (C / N ratio) may be mixed.

On the other hand, as the permeable and aerobic soil (18), in addition to masa soil, immature sand dune soil, coarse volcanic ash soil, coarse brown forest soil or coarse brown lowland soil is used. Further, zeolite is one of the most preferable.

The main role of this permeable and aerobic soil is
The purpose is to allow contact, diffusion, and permeation into the anaerobic soil layer (soil block (6)) as efficiently as possible, and prevent clogging of the device to allow rapid water permeation. In addition, mainly for this permeable and aerobic soil, SS content, BOD and
Aerobic decomposition, nitrification, and deodorization of COD and other organic substances are performed. Therefore, this soil is required to have high air permeability and high water permeability (for example, saturated water permeability coefficient higher than 10 ^-2 to 10 ^-3 cm / s). In some cases, sand, gravel, tree branches of appropriate size, artificial turf, or the like, which promote water permeability, may be mixed.

Generally, the concentration of monovalent Na ions in sewage (A) is divalent.
Since the concentration of Ca is higher than that of Ca ions, the soil colloid becomes Na type and easily disperses when the sewage is infiltrated for a long time, which is a major cause of irreversible clogging of the entire soil purification device. Therefore, when the limestone with a particle size of several cm is filled around the waste water sprinkling pipe (3) or Ca ions are added to the waste water at the previous stage, the Ca / Na ratio in the waste water (A) becomes It becomes higher and the soil colloid becomes Ca type and maintains a stable structure.

By the way, the degree of purification and the treatable amount by the device of the present invention vary depending on the roles and arrangement states of the permeable / aerobic soil (18) and the soil block (6), and also the type of soil used and the components contained therein. Therefore, it is advisable to concretely determine the optimum combination of soil layers depending on the quantity and quality of wastewater and the desired quality of purified water. Also, the more practical size of the equipment, especially the width and length, is determined by the amount of sewage treated, the structure of the equipment, the site area, etc., but the maximum width is 3 m and the length is about 20 m. It suffices if a large number of such devices are arranged in parallel. The bottom of the tank (7) may be omitted, and other materials such as concrete, plastic, clay, wood, etc. having a low water permeability claim may be used, and sometimes masonry or bedrock may be used.

(Other Embodiments) The wastewater purifying apparatus (1A) shown in FIGS. 3 and 4 is a bag body (4) smaller than that of the above example (8 × 25 × 75 cm size).
A soil block (6K) filled with 10 kg of black soil (6 layers) with a gap of about 2 cm, and 13 kg
This is a layer (2 layers) in which soil blocks (6R) filled with red soil are lined up with a gap of 2 cm above and below. Red soil is a substitute for black soil, and this ratio may be changed or only one of them may be used. In addition, since the soil blocks in the even-numbered stages are shifted by 1/2, both ends are filled with black soil or red soil.

Zeolite (clinoptiolite) particles having a particle diameter of 1 to 3 mm are filled in the gaps as the water-permeable / aerobic soil (18). In this device, the zeolite particles have a role of a water passage that prevents clogging and helps the permeation / flow of the treated water (B). Then, the treated water (B) is changed by changing the particle size of the zeolite used and the thickness of the zeolite layer.
The water permeability of the can be controlled. Further, since zeolite has a large ammonium ion retaining ability, it has an effect of prolonging the residence time of nitrogen in the apparatus. Further, the large CEC of zeolite has a buffering action against the pH drop of the treated water (B) due to nitrification, and protects the microbial activity in the device. In addition, it becomes a home for each microorganism. The zeolite may be of the mordenite type.

In this device (1A), as shown in Fig. 4, the jute bag (4) and the zeolite are in a state in which the black soil (red soil) is double-coated, and these act organically. In addition to its ability to decompose organic pollutants (BOD, COD, SS) in wastewater, it also has an extremely excellent ability to purify phosphorus and nitrogen. In the figure, the solid arrow indicates the flow of treated water (B) in the permeable / aerobic soil (18), and the dotted arrow indicates the impervious water.
The flow of the treated water (B) in anaerobic soil (5) is shown.

Next, the sewage purification apparatus (1B) shown in FIG. 5 shows an example in which a water-permeable container (19) is used instead of the bag body (4). This container (19) has a through hole (2) on the bottom surface (20) as shown in FIG.
1) A tray-like wooden box with a large number of ... In addition, the dimension a on the upper side and both sides of the tab surface (22)
Protrusions b and b are provided so that a gap can be formed when a large number are stacked. Further, the through holes (21) may be enlarged and closed with a net-like body for preventing soil from falling off.

And, this container (19) is filled with black soil and red soil to make a hardly permeable / anaerobic soil block (23K) / (23R), and it is filled with zeolite particles to make a permeable / aerobic soil block (23Z). The purification layer (8) is obtained by laying and stacking these as shown in the figure. And, between each soil block (23)…, a gap of acm in the vertical direction and bcm in the longitudinal direction (2
4) is formed, and the gap (24) serves as a passage for the treated water (B) and purified water (C) and gives an aerobic atmosphere.

The role of the black soil (red soil) in this device (1B) is the same as that in the device (1A). However, in this example, the zeolite is also soil-blocked. Therefore, since all soil can be unitized, labor saving in construction,
It is useful for standardization and has a feature that the flow of sewage can be easily controlled by adjusting the gap between each soil block (23). In addition, the wooden box with a high carbon rate is itself a carbon source for denitrifying bacteria, similar to the jute bag (4).
Achieves efficient nitrogen purification capacity.

The container (19) may be a wooden box, a corrugated box, or any other source that supplies a carbon source by being subjected to microbial decomposition. The shape of the container and the number, shape and position of the through holes may be appropriately selected.
In addition, a plastic porous molding can be used as the container. However, in that case, it is preferable to separately mix a carbon source in the filled soil. As a modified example of this device (1B), other permeable / aerobic soil (18) such as masa soil is used in place of zeolite, and the gap (24) is enlarged to have permeable / aerobic soil (18) here. It is conceivable to fill the Further, although not shown, it is also possible to form the purification layer (4) by supporting a bag (4) filled with soil with a pipe or the like installed vertically and horizontally with a vertical gap.

The above has described the case where the waste water sprinkling pipe (3) is arranged in the covered soil layer (2) as a waste water supply source, but the present invention is naturally applicable to the waste water tank (25) as shown in FIG. Used. In this case, the purification layer (8) as described above may be spread around and around the opening of the dirty water tank (25). Further, even when using the sewage sprinkling pipe (3), the purification layer (8) may be arranged on the side or the upper side thereof.

Although there are various other conceivable methods of supplying the sewage and the structure of the upper portion of the purification layer (4), the point is that the treated water (B) is supplied to the efficiency bath purification layer (4). Alternatively, it is conceivable to increase the layer of masa soil in the purification layer (4) itself so that the nitrification reaction also takes place there.

(Comparison with Conventional Soil Purifying Device) Next, Table 1 shows the results of comparing the sewage purification performance of the device of the present invention with the conventional simple multi-stage soil layer method.

In the table, the device of the present invention (embodiment) means that the embodiment 1 has the structure shown in FIG. 1, the embodiment 2 has the structure shown in FIG. 3, and the embodiment 3 has the structure shown in FIG. belongs to. A conventional multistage device (comparative example) has a structure shown in FIG. Content of active aluminum and active iron in Masa soil and Kuroboku soil used for each of these devices (based on dry soil weight)
Were 0.1 and 0.3%, 5.6 and 0.6%, respectively.

The comparative device also has a multi-stage soil layer structure and has a high degree of purification as can be seen from the table, but all the devices of the examples have a practically sufficient treatable capacity (l / m ² · day). Moreover, the purifying ability is equal to or higher than that of the comparative example. In particular, the one shown in Example 2 has an extremely high nitrogen purifying ability, and other BOD
It can be said that it has excellent purifying ability and is excellent.

On the other hand, the time required for constructing the apparatus of FIG. 1 (Example 1) and the conventional multi-stage apparatus (Comparative Example) shown in FIG. 9 having substantially the same structure is about 2 days and 4 days, respectively. In the case of the device of the present invention, the efficiency is improved about twice or more. This difference becomes larger in a large-scale actual device, and the difference becomes larger when the structure is complicated. Further, in the case of the present invention, the work as designed can be easily performed, and the expected effect is exhibited.

[Effect] As described in detail above, the present invention is difficult to permeable to water and anaerobic when constructing a sewage purification device by a multi-stage soil layer method in which layers or groups of hardly permeable / anaerobic soil and permeable / aerobic soil are laminated A certain amount of soil or water-permeable / aerobic soil is filled in a bag or container having excellent water permeability to form a kind of block, and this soil block is laid and accumulated.

Therefore, according to the present invention, a multi-stage soil layer type sewage purification device having a complicated structure can be accurately manufactured as designed, and its function can be fully exerted and standardization can be performed without labor and construction cost. Can be reduced. Further, if a bag or a container for forming a soil block having a high carbon content is used, it has various advantages in economic and technical aspects such as a remarkable denitrification reaction.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an example of the wastewater purifying apparatus according to the present invention, FIG. 2 is a transverse sectional view showing the same, FIG. 3 is a longitudinal sectional view showing another embodiment, and FIG. FIG. 5 is a partially enlarged view, FIG. 5 is a vertical cross-sectional view of a sewage purification device showing still another example, and FIG.
FIG. 7 is a perspective view of a water-permeable container used in the apparatus of FIG. 7, FIG. 7 is a partially enlarged view of FIG. 5, FIG. 8 is a vertical cross-sectional view of a wastewater purification apparatus showing another example in which wastewater supply sources are different, It is a longitudinal cross-sectional view showing a conventional example. 1.1A ・ 1B …… Sewage purification device 2 …… Coated soil layer 3 …… Sewage sprinkling pipe 4 …… Bag 5 …… Impermeable water / anaerobic soil 6.6K ・ 6R …… Soil block 8 …… Purification layer 9 …… Drainage layer 13 …… Trench 15 …… Drain pipe 18 …… Permeable / aerobic soil 19 …… Container 23K.23R.23Z …… Soil block 24 …… Gap 25 …… Sewage tank A …… Sewage B… … Treated water C… Purified water

Claims (5)

[Claims] 1. A container or a bag having water permeability, which is poor in air permeability and water permeability but is rich in activated aluminum or iron, is filled with a soil layer having excellent air permeability and water permeability. A sewage purification device characterized by having a purification layer that has been stacked. 2. The sewage purification device according to claim 1, which uses a container or a bag made of a material having a high carbon rate. 3. A water-permeable container or bag filled with soil having excellent air permeability and water permeability, and a water-permeable container filled with soil having poor air permeability and water permeability but rich in active aluminum or iron. A sewage purification device comprising a purification layer in which a bag body is stacked in layers and in a stepwise manner with a space provided around the bag body. 4. The sewage purification device according to claim 3, wherein the surrounding voids are filled with soil having excellent air permeability and water permeability. 5. The sewage purification device according to claim 3, which uses a container or a bag made of a material having a high carbon rate.