JP2002273471A - Equipment and method for purifying water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide equipment and a method for purifying water which can prevent eutrophication economically even in a closed water area of a large capacity. SOLUTION: This water purifying equipment 1 is provided with a cut-off area forming member (impermeable sheet 5) forming a cut-off area 11 to which supplying of oxygen is cut of at a part of water mass (stagnated water 2) in a stagnated water area and an anaerobic state generation means for making the area 11 anaerobic. The equipment is used for the water purifying method for reducing nitride concentration in the stagnated water area such as the closed water area, a water reservation tank by using physical, chemical or biological ability for purifying water which natural ecosystem has.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying water under anaerobic conditions and a method of purifying water under anaerobic conditions using water masses under anaerobic conditions, and more particularly, to preventing eutrophication of closed water areas and stagnant water areas. The present invention relates to a water purification apparatus and a water purification method under anaerobic conditions which can be used for direct purification or purification of general wastewater.

[0002]

2. Description of the Related Art In recent years, water quality of rivers has been improved, but water quality of closed water areas such as lakes, dams, reservoirs, and inner bays has been stagnant or deteriorating. The cause of this is thought to be the large effect of internal production by phytoplankton in eutrophic enclosed waters, and nitrogen is a problem as one of the causative substances of this eutrophication.

[0003] On the other hand, there is a strong demand for flushing toilets in areas where sewerage is not maintained. Under such conditions, the combined treatment septic tank, which treats human waste and household wastewater (kitchen, laundry, bath drainage, etc.) together, is relatively inexpensive and easy to install, and because the quality of the discharged water is good, It is being taken up by many municipalities as an effective means of preventing the deterioration of the living environment due to gray water and the pollution of public water bodies such as rivers, lakes, and the sea.

[0004] However, it is said that the combined treatment septic tank generally has a larger unprocessed amount of nitrogen than the collection treatment.
For this reason, in the closed water body from which the water purified by the combined treatment septic tank is discharged, it is expected that the eutrophication will further progress due to the untreated nitrogen.

[0005] Further, in a closed water body in which the sediment has deteriorated due to such eutrophication, ammonia nitrogen and the like are eluted from the sediment which has been subjected to anaerobic conditions, and a vicious cycle that eutrophication further progresses. Get up.

[0006] As a technique for removing nitrogen flowing into such a closed water area, for example, absorption removal using a plant or removal by sedimentation dredging is performed.

However, in the absorption removal using plants and the removal of sediment by dredging, the amount of nitrogen that can be economically removed is small, and at present, there is an effective nitrogen removal technology from closed water bodies. Absent.

Further, as a measure for improving the sediment quality, techniques for supplying dissolved oxygen to the bottom layer to eliminate anaerobic conditions, such as aeration of the bottom layer and a method of sending water containing a large amount of dissolved oxygen in the surface layer, have been developed.

[0009] However, if the sediment is purified only under aerobic conditions, there is a concern that nitrogen sources such as nitrites and nitrates may accumulate in the water because the substance metabolism is biased only in the oxidation direction.

On the other hand, the water purification method using both the purification by microorganisms under aerobic conditions and the purification by microorganisms under anaerobic conditions can increase the amount of nitrogen removed. And some have been put to practical use.

For example, as a nitrogen removal technique using microorganisms in sewage treatment, nitrogen is purified (oxidized) to nitrate nitrogen in aerobic treatment, and then this nitrate nitrogen is removed under anaerobic conditions by denitrifying bacteria. Techniques have been established to remove nitrogen gas from the aquatic atmosphere into the atmosphere using the denitrification effect of the work. This technology is applied to nitrogen removal countermeasures in sewage treatment plants and nitrogen removal type combined treatment septic tanks.
It is disclosed in the standard denitrification treatment system shown in the “National Urban Cleaning Council”.

JP-A-1-281198 discloses a water tank partitioned by a porous or fibrous partition, and an anaerobic water sealed by the partition is provided below the partition. A space is formed, while a water space to be treated is formed above the partition, in which oxygen is supplied and the aerobic condition is maintained.

The partition has a special water-permeable structure in which aerobic microorganisms are supported in layers on the water space to be treated and anaerobic microorganisms are supported in layers on the enclosed anaerobic water space. A carrier is used. Thereby, the water to be treated is brought into contact with aerobic microorganisms and anaerobic microorganisms, and water treatment under aerobic conditions and anaerobic conditions is performed in the same water tank to purify the treated water.

According to Japanese Patent Application Laid-Open No. H11-114593, a hypoxic region having a low oxygen concentration is formed in water, and a heterotrophic bacterial group that is implanted in an environment with low dissolved oxygen in the anoxic region is solidified. Water purification by supplying organic carbon, such as polymer biodegradable resin and natural polysaccharide liquid, to convert oxides and final oxides present in water into harmless gases by reduction such as denitrification A method has been proposed.

The oxygen-deficient region is provided inside or outside the water tank. For example, the oxygen-deficient region in the water tank is provided with a sand layer at the bottom in the water tank, and the stagnant area of the water flow in the lower part of the sand layer is defined as the oxygen-deficient region, or a housing having a small hole at the bottom of the water tank is provided. The inside of the housing is defined as an oxygen-deficient region, or a filter is provided at the bottom of the water tank, and the lower portion is defined as the oxygen-deficient region. In addition, the oxygen-deficient region outside the water tank is, for example, formed as an oxygen-deficient region by forming a stagnant region of water inside a filter housing installed outside the water tank by an appropriate method. Further, in the case of water existing in the natural world, an anoxic region is set at a position where only a small amount of water passes under the soil on the bottom surface. A part of the water to be purified is supplied to each of the anoxic regions very slowly, and the treated water is discharged into the water to be purified and circulated.

[0016]

However, in Japanese Patent Application Laid-Open No. 1-281198, it is described that water is most advantageous when used for water containing organic substances originating from nature. According to the disclosed water purification method, a special carrier such as a water-permeable porous partition that supports aerobic microorganisms and anaerobic microorganisms in layers is required. For this reason, in fact, the invention is intended for purification of a closed water area of the size of an artificial aquarium such as a fish tank, and is not intended for use in a large-scale closed water area targeting natural terrain. Seems unsuitable. Further, if the porous carrier as such a partition is clogged, it is necessary to wash or replace the entire partition.

The water purification method described in JP-A-11-114593 is considered to be suitable for treating low-concentration nitrogen generated in a natural circulation cycle. The method of forming the oxygen region requires a small volume of the region, and requires a special filtering material and a housing having a predetermined shape. For this reason, it is considered that if the volume of the oxygen-deficient region is small, it is not suitable for purification of the treated water contaminated with high concentration.

For example, if an oxygen-deficient region is provided below a sand layer, a sufficient volume cannot be secured when the concentration of nitrogen to be treated is high. In addition, in order to install a fixed building such as a housing, there is a problem in selecting an installation place of the housing, and a housing that can secure a sufficient volume becomes large. In addition, when a special filter medium is used, it is necessary to wash or replace the special filter medium similar to that described in the case of Japanese Patent Application Laid-Open No. 1-281198. It is considered unsuitable for improving the water quality of lakes and marshes.

Accordingly, an object of the present invention is to provide a water purification apparatus and a water purification method capable of economically preventing eutrophication and conserving water quality even in a large-capacity closed water area. . An object of the present invention for this purpose is to reduce the concentration of highly contaminated nitrogen in closed waters, which is one of the causative substances of eutrophication. Another object of the present invention is to improve the deteriorated sediment so as to eliminate a vicious cycle in which eutrophication is accelerated due to the adverse effect from the deteriorated sediment.

[0020]

According to the first aspect of the present invention,
An apparatus used in a water purification method for reducing nitrogen concentration in a stagnant water area such as a closed water area or a water tank using a physical, chemical or biological water purification ability of a natural ecosystem, wherein A blocking region forming member that forms a blocking region that blocks supply of oxygen to a part of the water mass in the water area,
An anaerobic state generating means for setting the blocking area in an anaerobic state.

According to this structure, the cut-off region forming member forms a cut-off region in which supply of molecular oxygen such as dissolved oxygen is cut off to a part of the water mass in the closed water area or the stagnant water area such as the storage tank. The cut-off area is made anaerobic by the anaerobic state generating means.

In the anaerobic blocking region, nitrogen is reduced by being purified by the action of anaerobic microorganisms existing in nature.

According to a second aspect of the present invention, there is provided the water purification system according to the first aspect, wherein the anaerobic state generating means is formed of a geological material surrounding the cutoff area and exuding a reducing substance to the cutoff area. Device.

According to this structure, since the reducing substance contained in the geology surrounding the cutoff region seeps into the cutoff region, the cutoff region can be made anaerobic.

Generally, sediment existing at the bottom of a closed water area contains a lot of organic matter derived from plant remains such as fallen leaves and plankton remains. Since these organic substances are reducing substances and are released from the sediment, the cut-off region in contact with the sediment can be in an anaerobic state with a small amount of dissolved oxygen (poor oxygen).

Thus, as the organic carbon source required for the denitrification, the one contained in the sediment can be used, so that the sediment can be improved at the same time. Purification can be performed by effectively utilizing the anaerobic water and the deteriorated sediment at the bottom of the stagnant water area such as the closed water area.

The invention according to claim 3 is characterized in that the anaerobic state generating means is an organic carbon supply device for supplying organic carbon artificially to the cutoff region. It is a water purification device.

According to this structure, the blocking region is reduced by the organic carbon added to the blocking region, and the blocking region can be brought into an anaerobic state. In addition, since the artificially added organic carbon is oxidized by the action of anaerobic microorganisms (denitrifying bacteria) and is emitted as carbon dioxide gas, it can be added as a substance that artificially creates anaerobic conditions. It does not pollute the water quality.

As such an organic carbon supply device,
It is an addition container for directly adding organic carbon such as liquid such as methyl alcohol or solid such as cellulose to anaerobic water area, or water area anaerobic for wastewater containing organic carbon such as domestic wastewater. It may be a water conveyance device that directly conveys water to the water.

According to a fourth aspect of the present invention, the blocking area forming member is a water blocking sheet that blocks a part or the whole of the bottom of the stagnant water area from the water surface.
3. A water purification device according to any one of the above items 3.

According to this structure, part or all of the bottom of the stagnant water area, such as a closed water area or a water storage tank, is covered with the impermeable sheet, so that the water mass below the impermeable sheet is separated from the water surface. Is done. In the separated body of water, the inflow of upper layer water and the supply of dissolved oxygen from the water surface or upper layer are cut off, thereby forming a cutoff region. According to the formation of such a blocking area, since the water blocking material is in a sheet shape,
It is easy to cope with a case where a large blocking area is desired.

Here, if the bottom of the cut-off region is provided with a sediment containing a large amount of organic matter, the cut-off region can be made anaerobic without artificially supplying organic carbon.

According to a fifth aspect of the present invention, there is provided the water quality according to any one of the first to fourth aspects, wherein the water blocking device is provided in the cutoff area with a drainage water containing nitrite nitrogen or nitrate nitrogen. It is a purification device.

According to this structure, the wastewater containing nitrite nitrogen or nitrate nitrogen is introduced into the shut-off region with low dissolved oxygen (anaerobic state) by the water introduction device, thereby preventing the action of anaerobic microorganisms and the like. Thus, nitrogen in wastewater can be removed at the same time. Here, nitrate nitrogen becomes nitrogen gas and is removed from the hydrosphere by the action of the denitrifying bacteria.

According to a sixth aspect of the present invention, a part of the water-impervious sheet is provided with a weight for sinking the water-impervious sheet to the bottom of the water, and a part of the water-impervious sheet is suspended from above the water surface. The water purification device according to claim 4, further comprising a device.

With this configuration, the impermeable sheet can be suspended from the water surface or the shore by a suspending device such as a rope, and can be installed at an appropriate position in the water area. This hanging device can be floated on the water surface by a float or the like.

The invention according to claim 7 is characterized in that a part of the water-impervious sheet is provided with a gas discharging device for discharging gas retained under the water-impervious sheet. It is a water purification device.

In the anaerobic purification, nitrogen gas or carbon dioxide gas is generated, which may cause the gas to stay under the water-impermeable sheet and float up the water-impermeable sheet. The water impermeable sheet can be stably held in water without floating.

According to an eighth aspect of the present invention, there is provided a water purification device, wherein the gas discharging device according to the seventh aspect is suspended by the suspending device according to the sixth aspect.

According to this structure, the gas generated by the anaerobic purification is concentrated and stays in the vicinity of the gas discharge device suspended by the suspension device, so that the gas can be efficiently discharged. Can be.

According to a ninth aspect of the present invention, the blocking area forming member is provided with a structure other than an inflow port through which the water mass to be treated in the stagnant water area flows in sequentially or continuously and a discharge port through which the treated water is discharged. Is formed by shutting off the inflow of water from the stagnant water area and the supply of dissolved oxygen by a tubular body such as a closed vessel or a hose, and the tubular body is artificially added to the shutoff region. The water purification device according to claim 1, further comprising an organic carbon supply device that supplies organic carbon.

With this configuration, the supply of dissolved oxygen is cut off in the tubular body to form a cut-off region, and organic carbon is supplied artificially to the cut-off region by the organic carbon supply device. The state is maintained. This allows the blocking area to be transferred sequentially or continuously through the tubular body from the inlet to the outlet, but the tubular body is elongated so that a longer residence time can be gained and during this longer residence time. The blocking area in the tubular body becomes anaerobic, and anaerobic purification can be performed in this tubular body.

According to a tenth aspect of the present invention, the tubular body is
The water purification device according to claim 9, wherein the water purification device is suspended on the water surface or in the water in the stagnant water area.

With this configuration, even if the length of the tubular body is long, the tubular body is suspended on the water surface or in the water, so that a special place for installing the tubular body is not required.

The invention according to claim 11 is characterized in that the water purification device according to claim 9 or 10 is provided with a water guiding device for guiding waste water containing nitrite nitrogen or nitrate nitrogen in the cutoff region. is there.

According to this structure, the waste water containing nitrite nitrogen or nitrate nitrogen is guided by the water guide device to the shut-off area where the dissolved oxygen is low (anaerobic state), so that the action of the anaerobic microorganisms and the like can be prevented. Thus, nitrogen in wastewater can be removed at the same time. Here, nitrate nitrogen becomes nitrogen gas and is removed from the hydrosphere by the action of the denitrifying bacteria.

According to a twelfth aspect of the present invention, in the water purification apparatus, the water purification apparatus further comprises a water-impervious tank having a sloped water-impervious bottom surface, in which soil having a water-purifying ability is filled under aerobic conditions. A water supply unit for supplying treated raw water to be treated to the impermeable tank, and a discharge unit for discharging treated water treated in the impermeable tank,
The water purification apparatus according to claim 5, further comprising: an inclined soil tank configured of: and the discharge unit is connected to a water guide device that guides water to the cutoff region.

With this configuration, the treated raw water is purified by the inclined soil tank by the purification ability of the soil. However, since this purification is mainly performed under aerobic conditions, the concentration of nitrate nitrogen is relatively high. There are cases. The high (rich) waste water containing nitrate nitrogen is led to the cut-off area by the water guiding device.
Since the cutoff area is in an anaerobic state, nitrate nitrogen in the wastewater is discharged as nitrogen gas by the action of the denitrifying bacteria.

Such an inclined soil tank can be disposed adjacent to a closed water area, or can be formed on a floating facility floating in the closed water area.

According to a thirteenth aspect of the present invention, the inclined soil tank has a stagnant portion formed by erecting a water-impervious plate for impervious to the road from the bottom wall of the water-impervious tank. The water purification apparatus according to claim 12, wherein

According to this structure, by providing the water impermeable tank with the retaining portion, the residence time of the water impermeable tank can be increased, and sufficient aerobic purification can be performed even with a small water impermeable tank.

Such a sloping earth tank is particularly advantageous because the apparatus can be miniaturized when floating in a closed water area.

If a ventilation structure for purifying water under aerobic conditions is buried on the downstream side of the stagnant portion, purification under aerobic conditions can be carried out efficiently and floating in closed water bodies. This is particularly advantageous because the size of the device can be reduced.

The invention according to claim 14 is a container-like structure in which the inclined soil tank has a water-shielding bottom surface and side surfaces,
The container-like structures are stacked in the direction of gravity to form a water purification device, a drain port is disposed near the lowermost end of the bottom surface in the direction of gravity, and treated water flowing out of the drain port is disposed upstream of the lower inclined soil tank. The water purification device according to claim 12, wherein the water purification device is disposed so as to flow down.

According to this structure, the inclined soil tank can be reduced in size, so that the purification device using the inclined earth tank can be installed at any location by adjoining to the closed water area or floating in the closed water area. Can be connected.

According to a fifteenth aspect of the present invention, the water purification device includes a stagnant water supply device for supplying the stagnant water in the stagnant water area to the water supply section of the inclined soil tank according to any one of the twelfth to fourteenth aspects. It is a water quality purification device characterized by having.

With this configuration, not only anaerobic purification of the stagnant water in the stagnant water area but also purification under aerobic conditions can be performed. Although the treated water purified in the inclined soil tank may have a high nitrogen content, the treated water is purified under anaerobic conditions in a shut-off area provided in the stagnant water area and is discharged as nitrogen gas.

[0058] The invention of claim 16 is a water purification system that utilizes the physical, chemical or biological water purification ability of a natural ecosystem to reduce the nitrogen concentration in a stagnant water area such as a closed water area or a water storage tank. A method, wherein artificially shielding a part of the water mass of the stagnant water area to form a cut-off region where supply of oxygen is cut off, and artificially supplying organic carbon to the cut-off region. A method for purifying water, characterized in that the cut-off area is made anaerobic, and the anaerobic cut-off area is purified by microorganisms existing in nature.

According to this structure, an artificial oxygen blocking region is formed in the stagnant water region, and organic carbon is artificially supplied to the blocking region. This blocking region is reduced by the organic carbon. The cut-off area is made anaerobic. Subsequently, the anaerobic water region thus formed can be anaerobically purified by microorganisms existing in nature.

The organic carbon supply source may be an organic carbon itself such as a liquid such as methyl alcohol or a solid such as cellulose, or may include an organic carbon such as domestic wastewater. May be sewage.

[0061] The invention of claim 17 is a water purification system that reduces the nitrogen concentration in a stagnant water area such as a closed water area or a water storage tank by utilizing the physical, chemical or biological water quality purification ability of a natural ecosystem. A method, wherein artificially shielding a part of the water mass of the stagnant water area including the sediment to form a shut-off area in which the supply of oxygen is cut off, and forming the shut-off area by microorganisms existing in nature. It is a water purification method characterized by purifying.

According to this structure, the cutoff region artificially formed in the stagnant water area includes the sediment, from which the reducing substance is exuded. Then, the cut-off region is reduced by the reducing substance to an anaerobic state, whereby
This anaerobic zone can be anaerobically purified by naturally occurring microorganisms.

As a result, purification can be performed by effectively utilizing the anaerobic water and the deteriorated sediment at the bottom of a stagnant water area such as a closed water area where only the adverse effects have been emphasized.

The invention according to claim 18 is characterized in that treated raw water containing nitrite nitrogen or nitrate nitrogen is introduced into the cut-off area to remove nitrogen mainly by a denitrification reaction. Item 18. A water purification method according to item 16 or 17.

With this configuration, by feeding treated raw water containing nitrite nitrogen and nitrate nitrogen to the cut-off region, it is possible to remove nitrogen from treated raw water such as wastewater by denitrification.

The invention according to claim 19 is characterized in that the treated raw water is obtained by purifying surface water containing phytoplankton generated in large quantities in the stagnant water area under aerobic conditions. The water purification method according to claim 18, wherein

With this configuration, anaerobic purification of a closed water area is performed by utilizing the large amount of phytoplankton in the surface water having a higher nitrogen concentration than the middle and lower layer water in which phytoplankton is not generated in large amounts. be able to.

The stagnant water in the stagnant water area at the portion where the water bloom has been generated is supplied to a purifying device under aerobic conditions such as an inclined soil tank by a stagnant water supply device, and then guided to an anaerobic water region. In this purification under aerobic conditions, the biochemical oxygen demand, suspended solids and total phosphorus are purified.

Organic nitrogen, which is nitrogen contained in plankton, is converted into nitrite nitrogen and nitrate nitrogen through ammonia nitrogen in purification under aerobic conditions (inclined soil tank), and almost nitrogen is removed. Becomes nitrate nitrogen. This nitrate nitrogen is purified and released as nitrogen gas in the anaerobic water region.

Thus, even when water blooms occur on the surface layer of a closed water area, the loads of a large amount of biochemical oxygen required, the total amount of suspended matter, and the total amount of nitrogen contained in the water blooms are reduced. Can be done.

[0071]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described.
Will be described based on the drawings.

First, FIG. 5 is a diagram for explaining an example of a closed water area such as a lake, a marsh, a dam reservoir, an inner bay, and the like. A sediment 4 containing organic matter is deposited on a bottom surface 3 of a stagnant water 2 retained inside. ing. Sewage such as domestic wastewater flows into the closed watershed through the inflow pipe 17 and the like.

The sediment of the closed water area contains a lot of organic matter derived from plant remains such as fallen leaves and plankton remains. In addition, since these consume the dissolved oxygen in the water, oxygen in the bottom layer is lost during the stratification period when the up-down mixing of water stops, and nitrogen and phosphorus are eluted from the sediment 4 and the phenomenon that the eutrophication state worsens is also observed. Can be As a result, the eutrophication of the closed water area is progressed by the untreated nitrogen in the sewage, and ammonia nitrogen and the like are eluted from the sediment 4 under the anaerobic condition, and the eutrophication further progresses. Has been repeated.

The first embodiment of the present invention provides a water purification apparatus and a water purification method capable of simultaneously performing the drainage countermeasure for sewage and improving the sediment in such closed water areas.

In FIG. 1, reference numeral 1 denotes a water purification device according to Embodiment 1 of the present invention, in which stagnant water 2 which is eutrophically enriched and needs to be purified is retained, and the water bottom 3 is to be reformed. It has sediment 4.

The water purification device 1 includes a water-blocking sheet 5 as a blocking area forming member.
Is provided with a plurality of degassing valves 6 arranged at appropriate intervals and a plurality of weights 7 (7a, 7b) arranged between the degassing valves 6, 6 and on the peripheral edge 5a of the impermeable sheet 5. I have.

On the other hand, a plurality of floats 9 are suspended on the water surface 8 of the closed water area, and the floats 9 are connected to a gas release valve 6 or a rope 10 connected to a water shielding sheet 5 near the gas release valve 6. Are linked. In this way, in the lower part of the water-blocking sheet 5, a blockage area in which the supply of dissolved oxygen is cut off by cutting off a part of the water mass of the stagnant water 2 from the water surface 8 and another water mass (stagnant water 2) 11 are formed.

On the other hand, on the shore 12, an inclined soil tank 13 is provided as a nitrate nitrogen supply source. This inclined soil tank 1
Reference numeral 3 denotes a water supply unit 15 formed of a water-impervious tank 14 having a water-impervious inclined bottom surface 14a. The water supply unit 15 supplies the raw water to be treated to the water-impervious tank 14; And a section 16.

The impermeable tank 14 is formed by stacking a plurality of container-like structures in which soil having a water purification ability is filled while maintaining aerobic conditions, in the direction of gravity.
A drain port is arranged near the lowermost end in the gravity direction of each inclined bottom surface 14a, and the treated water flowing out from the drain port is arranged to flow down to the upstream side of the lower container-like structure. Thereby, the water-blocking tank 14 is downsized while maintaining the residence time.

An inflow pipe 17 is connected to the water supply section 15, and sewage such as domestic wastewater discharged into the closed basin flows in. In addition, the discharge section 16 has a
A water pipe 18 extending from the outlet 18a is connected. Further, the impermeable sheet 5 near the discharge port 18a
a is grounded by the weight 7a.

Next, the operation of the water purification device 1 configured as described above will be described.

As shown in FIG. 5, in a closed water area in which the water purification device 1 of the present invention is not installed, the inflow pipe 17 flows directly into the vicinity of the surface of the stagnant water 2 in the closed water area, and is stagnated. The water quality of water 2 is getting worse.

On the other hand, according to the water purification apparatus 1 of the present invention, a part of the stagnant water 2 in the stagnant water area is shut off by the impermeable sheet 5 to form the shut-off area 11. Since the cutoff region 11 contains the sediment 4, the reducing substance contained in the sediment 4 exudes to the cutoff region 11. The cut-off region is reduced by the reducing substance, and the dissolved oxygen is consumed, so that an anaerobic state in which the dissolved oxygen is low (poor oxygen) is obtained. In the anaerobic cut-off area 11, anaerobic purification is performed by the action of anaerobic microorganisms (denitrifying bacteria) present in the stagnant water 2 and the sediment 4.

On the other hand, the sewage is supplied from the inflow pipe 17 to the inclined soil tank 1.
3 As a result, this sewage is transferred to the inclined earth tank 13.
The purification is carried out by the purification ability of the soil inside, and since this purification is purification under aerobic conditions, the nitrogen content contained in the sewage is reduced to nitrous acid or nitric acid when discharged from the discharge port 18a. Purified to form nitrogen.

This high (rich) wastewater of nitrate nitrogen is
It is guided to the blocking area 11 by the water guide pipe 18. Here, since the cutoff area 11 is in an anaerobic state, nitrate nitrogen in the wastewater is denitrified (purified) by the action of denitrifying bacteria that inhabit the natural world such as in water or in sediment, and nitrogen gas is released. . At the same time, the denitrifying bacteria decompose the organic carbon contained in the sediment rich in organic matter and the organic carbon leached (or eluted) from the sediment to release carbon dioxide gas. The denitrification of nitrate nitrogen is represented by the following equation.

2NO ₃ → N ₂ + 3O ₂ 3O ₂ + 3Org-C → 3CO ₂ As a result, the released nitrogen gas and carbon dioxide gas are scattered near the gas release valve 6 installed on the water shielding sheet 5, and this gas release is performed. After passing through the valve 6, it is discharged as bubbles 19 from the shut-off area 11. Here, since the position of the gas release valve 6 is suspended from the float 9 by the rope 10,
The gas discharged from the denitrifying bacterium can be efficiently removed by this degassing valve 6.
Dispersed nearby. Water purified under anaerobic conditions
The weight 7a, which flows gently in the direction of the arrow 20, is discharged from the impermeable area 11 near the weight 7b opposite to the weight 7a.

According to this structure, the sediment contained in the sediment can be used as the organic carbon source required for the denitrification, so that it is necessary to supply the carbon source necessary for the anaerobic microorganisms. And the improvement of the bottom quality can be performed at the same time. As a result, purification can be performed by effectively utilizing the anaerobic water at the bottom and the deteriorated sediment, such as a closed water area, where only the adverse effects have been emphasized.

Further, since anaerobic microorganisms existing in the natural world are used as they are, there is no need to provide a special carrier for supporting the microorganisms. Further, since no special microorganism such as activated sludge is used, there is no need to separate the activated sludge from the treated water. This makes it easy to use it practically even when the place where the water to be purified is stored is large.

In the first embodiment, the nitrogen in the sewage supplied from the inflow pipe 17 is purified to nitrite or nitrate nitrogen by including wastewater purified by a combined treatment tank or the like. If this is the case,
7 may be directly connected to the water guide pipe 18 without through the inclined earth tank 13 and introduced into the cutoff area 11. Thereby, substantially the same effect is expected.

The inclined soil tank 13 includes a water-tight tank 14.
A ventilation structure for standing up a water-impervious plate that blocks the road as well as the bottom surface 14a, and for purifying water under aerobic conditions downstream of the water-holding plate. By burying the soil, purification under aerobic conditions can be performed efficiently, and the device for the inclined soil tank can be reduced in size. Details of such an inclined soil tank 13 are disclosed in, for example, Patent Distribution Fair in Shikoku '99 and the like, and are disclosed in JP-A-11-319861, and Japanese Patent No. 307.
No. 6024 and the like.

[0091]

Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts as those in the first embodiment will be described with the same reference numerals.

First, FIG. 2 is a diagram for explaining a water purification apparatus and a water purification method using the same according to the second embodiment of the present invention. This is an example of improving the water quality and bottom quality of a closed water area closed by a dam dam (artificial weir) 22 or the like.

In this water purification apparatus 1, a floating island-like structure such as a barge 23 is arranged on the water surface 8, and the barge 2
3 is a water-impregnated tank 1 in which the number of polymerization stages of the container-like structure is two
And a water supply pump 24 that supplies surface water 21 to a water supply unit 15 of the inclined soil tank 13 through a water supply pipe 24a. Thereby, surface water 2
1 is pumped to the water supply section 15 of the inclined earth tank 13. A water guide pipe 18 is connected to the discharge part 16, and a discharge port 18 a at the tip of the water guide pipe 18 extends through the central part of the water shield sheet 5 and extends to the central part in the planar direction of the blocking area 11.

A plurality of floats 9 are arranged around the barge 23, and the water shield sheet 5 is hung down from the floats 9 and connected thereto. In this water-impervious sheet 5, a gas vent valve 6 is installed at the center, and a plurality of weights 7 b are fixed to the periphery of the water-impervious sheet 5. The rope 10 suspended from the float 9 is directly connected to the periphery 5a or the weight 7b of the impermeable sheet 5 to which the weight 7b is fixed. As a result, a part of the water mass of the stagnant water 2 is blocked by the water-blocking sheet 5, and a blocking area 11 in which the supply of oxygen from the water surface 8 is blocked by convection or the like is formed below the water-blocking sheet 5. Have been.

Next, the operation of the water purification apparatus 1 configured as described above will be described.

In this figure, a large amount of biochemical oxygen demand (BOD), suspended solids (SS), total phosphorus (TP) and total nitrogen are contained in the surface water 21 where a large amount of phytoplankton is generated. (T-N). This surface water 21
Water is supplied to the inclined soil tank 13 by the pump 24.

In the inclined soil tank 13, aerobic purification is performed, and organic contaminants represented by BOD, SS and the like are decomposed, and organic phosphorus and the like are also removed. Organic nitrogen (Org-) in the form contained in phytoplankton
N) is almost purified to nitrate nitrogen. This reaction is expressed as Org-N (organic nitrogen) → NH ₄ —N (ammonia nitrogen) → NO ₂ —N (nitrite nitrogen) → NO ₃ —N (nitrate nitrogen).

[0098] The treated water thus obtained contains nitrate nitrogen, flows into the center of the anaerobic impermeable area 11 from the discharge port 16 through the water guide pipe 18, and gently flows around the periphery along the arrow 20. Dissipated.

During this time, nitrogen is removed from the water and the sediment is purified in the impermeable area 11 by the action of the denitrifying bacteria. Here, the surface water 21 where a large amount of phytoplankton is generated is
Since the concentration of nitrogen and phosphorus is higher than that of the middle and lower layers of water not generated in large amounts, a large amount of nitrate nitrogen can be supplied from the water supply pipe 18. Thus, according to this method, nitrogen and phosphorus in a closed water area can be effectively removed by utilizing the mass production of phytoplankton. In addition, sediment quality can be improved.

Further, in such an apparatus, the inclined earth tank 13
Can be installed floating on the water surface 8, so that it is not necessary to secure a special place for installing the equipment.

[0101]

Third Embodiment Next, a third embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts as those in the second embodiment will be described with the same reference numerals.

The third embodiment relates to a water purification apparatus and a water purification method using the same in the second embodiment in which it is not necessary to improve the sediment, as shown in FIG.
In this water purification device 1, an anaerobic water purification container using a tubular body such as a hose 25 is used.

That is, the anaerobic water purification container of the third embodiment is formed of a hose 25 having both ends open as a water-blocking material, and the hose 25 has an addition container 26 as an organic carbon supply device. Are arranged at appropriate intervals. The addition container 26 is for supplying an organic carbon such as a liquid such as methyl alcohol or a solid such as cellulose to the treated water flowing down in the hose 25.

The hose 25 is floated in the water by being pulled by the float 9 by the rope 10. One end of the hose 25 is connected and fixed to the discharge portion 16 of the inclined earth tank 13, and the other end 2
5a is floating in water.

Next, the operation of the water purification apparatus 1 configured as described above will be described.

In this figure, the surface water 21 in which a large amount of phytoplankton has been generated is pumped by a pump 24 to the inclined soil tank 1.
3 and aerobic purification is performed in the same manner as in the second embodiment. Organic contaminants represented by BOD and the like are decomposed and phosphorus and the like are removed. The treated water thus obtained contains nitrous acid or nitrate nitrogen, and is discharged from the outlet 16 through the hose 25.
It is conducted inside. The supply of oxygen in the hose 25 is cut off, and the hose 25 is reduced by the organic carbon added by the addition container 19 to maintain an anaerobic state.

As a result, the treated water flows through the outlet 25 through the hose.
The anaerobic purification is performed during the gradual transfer toward the a, the nitrate nitrogen in the water guided by the action of the denitrifying bacteria is released as nitrogen gas, and the organic carbon added by the addition vessel 26 is converted into carbon dioxide gas. As each exit 25a
Is released as bubbles 19.

Thus, according to this method, the surface water 21 containing a large amount of phytoplankton can be purified without releasing nitrate nitrogen into the water by a combination of the inclined soil tank 13 and anaerobic purification.

Further, in such a water purification apparatus 1, since the inclined soil tank 13 and the hose 25 can be floated on the water surface 8 or can be installed by effectively using the water, it is necessary to secure a special place for installing the equipment. Nor.

[0110]

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts as those in the first embodiment will be described with the same reference numerals.

First, FIG. 4 shows a sewage purification apparatus in which the present invention and the inclined soil tank method are combined, and is shown in "Commentary Guideline for Sewage Treatment Facility Structure-1988 Edition-National Urban Cleaning Council". This is based on the principle of the standard denitrification process.

One end 27a of the water shielding sheet or plate 27
Anaerobic water purification tank 28 which is slightly open
It is installed substantially horizontally in the middle stage (hereinafter referred to as a water storage tank 28). The inflow pipe 17 of the sewage which is the raw water to be treated has its tip 17
a is extended and guided to one end of the bottom of the water storage tank 28.

A water supply pump 24 and an inclined soil tank 13 are provided around the water storage tank 28, and the water storage tank 28 is provided through a water supply pipe 24a.
Can be supplied from the water supply section 15 to the inclined soil tank 13. Then, the discharge section 16 of the inclined earth tank 13 is connected to the water pipe 1.
8, and the distal end 18 a of the water pipe 18 is disposed near the distal end 17 a of the inflow pipe 17.

As a result, the inside of the water storage tank 28 is
The upper layer 29 is in contact with the atmosphere, but the lower layer 30 can be the cut-off region 11 cut off from the upper layer 29 by the water shield plate 27.

According to the water purification apparatus 1 configured as described above, the sewage flowing from the inflow pipe 17 is maintained in an anaerobic state by the action of the reducing substance in the sewage in the cut-off region 11 of the lower layer 30. On the other hand, the supernatant water (dirty water) in the water storage tank 28 is supplied to the inclined soil tank 13 via the water supply pump 24. Purification under aerobic conditions is performed in the inclined soil tank 13, and organic nitrogen in the sewage is purified to nitrite or nitrate nitrogen, and supplied to the water storage tank 28 via the water pipe 18.

In the cut-off area 11, the organic carbon contained in the sewage supplied from the inflow pipe 17 is decomposed simultaneously with the denitrification of nitrous acid or nitrate nitrogen supplied from the water supply pipe 18 by the action of the denitrifying bacteria. It becomes nitrogen gas and carbon dioxide gas and is removed as bubbles 19. The treated water in the blocking area 11 is gently transferred to the upper layer 29 along the arrow 20 from the vicinity 27a of the tip. Thereby, the treated water in the water storage tank 28 is circulated and purified under aerobic conditions and anaerobic conditions.

FIG. 4 shows the simplest method, a batch method in which the whole is purified and then discharged, and as a countermeasure against wastewater having a high concentration of both organic matter and nitrogen in livestock wastewater, etc. Simple and effective.

[0118]

As described above, according to the present invention, even in a large-capacity closed water area, a water purification apparatus and a water purification method capable of economically preventing eutrophication and preserving water quality. Can be provided. In addition, it is possible to reduce the concentration of highly contaminated nitrogen in enclosed waters, which are considered to be one of the causative substances of eutrophication, and to improve the deteriorated sediment, Can eliminate the vicious cycle that accelerates eutrophication due to the adverse effects of.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a water purification device and a water purification method according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating a water purification device and a water purification method according to Embodiment 2 of the present invention.

FIG. 3 is a diagram illustrating a water purification device and a water purification method according to Embodiment 3 of the present invention.

FIG. 4 is a diagram illustrating a water purification device and a water purification method according to Embodiment 4 of the present invention.

FIG. 5 with sediment to be reformed

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water purification apparatus 2 Stagnant water (water mass of stagnant water area) 3 Water bottom 4 Sediment 5 Water shielding sheet (blocking area forming member) 6 Deaeration valve 7 Weight 8 Water surface 9 Float 10 Rope 11 Blocking area 13 Inclined soil tank 17 Inflow Pipe 18 Water pipe 19 Bubbles 21 Surface water 23 Barge 24 Feed pump

Claims (19)

[Claims] An apparatus used in a water purification method for reducing nitrogen concentration in a stagnant water area such as a closed water area or a water storage tank by utilizing a physical, chemical or biological water purification ability of a natural ecosystem. A blocking region forming member that forms a blocking region that blocks the supply of oxygen to a part of the water mass in the stagnant water region; and an anaerobic state generating unit that causes the blocking region to be in an anaerobic state. Water purification equipment. 2. The water purification apparatus according to claim 1, wherein said anaerobic state generating means is a geological material surrounding said cut-off area and exuding a reducing substance into said cut-off area. 3. The water purification apparatus according to claim 1, wherein said anaerobic state generating means is an organic carbon supply device for artificially supplying organic carbon to said cut-off region. 4. The water purification according to claim 1, wherein the blocking area forming member is a water blocking sheet that blocks a part or the whole of the bottom of the stagnant water area from the water surface. apparatus. 5. The water purification device according to claim 1, further comprising a water guiding device for guiding waste water containing nitrite nitrogen or nitrate nitrogen in the cutoff region. 6. A part of the water-impervious sheet is provided with a weight for sinking the water-impervious sheet to the bottom of the water, and a suspending device for suspending a part of the water-impervious sheet from above the water surface. The water purification apparatus according to claim 4, characterized in that: 7. The water purification apparatus according to claim 4, wherein a part of the water-impervious sheet is provided with a gas discharge device that discharges gas remaining under the water-impervious sheet. 8. A water purification device according to claim 7, wherein the gas discharge device is suspended by the suspension device according to claim 6. 9. The container in which the blocking area forming member is hermetically sealed except for an inflow port through which water to be treated in the stagnant water area flows in sequentially or continuously and an outlet through which treated water is discharged. Or, the inflow of water from the stagnant water area and the supply of dissolved oxygen are cut off by a tubular body such as a hose, and the tubular body is supplied with organic carbon that is artificially added to the shutoff area. The water purification device according to claim 1, further comprising an organic carbon supply device. 10. The water purification device according to claim 9, wherein the tubular body is suspended on the surface of the stagnant water area or on the water. 11. The water purification device according to claim 9, further comprising a water guiding device for guiding waste water containing nitrite nitrogen or nitrate nitrogen in the cutoff region. 12. The water purification device according to claim 1, wherein the water purification device has an inclined water-impervious bottom surface, and a water-impregnated tank in which soil having a water-purifying ability is filled under aerobic conditions. A water supply section for supplying treated raw water to be treated, and a discharge section for discharging treated water treated in the impermeable tank, wherein the inclined section is configured with an inclined soil tank, and the discharge section is connected to the water guide device. The water purification device according to claim 5 or 11, wherein: 13. The inclined soil tank according to claim 12, further comprising a retaining portion formed by erecting a water impervious plate for impervious to a water path from a bottom wall of the water impervious tank. Water purification device. 14. The inclined soil tank is a container-like structure having a bottom surface and a side surface made of water-blocking, and the container-like structures are stacked in the direction of gravity to form a water purification device. The drainage port is disposed near the lowermost end in the direction of gravity, and the treated water flowing out of the drainage port is disposed so as to flow down to the upstream side of the lower inclined soil tank. Water purification device. 15. The water purification apparatus further comprises a stagnant water supply device for supplying the stagnant water in the stagnant water area to a water supply unit of the inclined soil tank according to any one of claims 12 to 14. Water purification equipment. 16. A water quality purification method for reducing nitrogen concentration in a stagnant water area such as a closed water area or a water storage tank by utilizing a physical, chemical or biological water quality purification ability of a natural ecosystem. An artificially shielded part of the water mass in the stagnant water area to form a cutoff region in which the supply of oxygen is cut off, and the cutoff region is anaerobically supplied by artificially supplying organic carbon to the cutoff region. Wherein the anaerobic blocking area is purified by microorganisms existing in nature. 17. A water purification method for reducing nitrogen concentration in a stagnant water area such as a closed water area or a water storage tank by utilizing a physical, chemical or biological water purification ability of a natural ecosystem, Forming a cutoff region in which the supply of oxygen is cut off by artificially shielding a part of the water mass of the stagnant water area, including the sediment, and purifying the cutoff region by microorganisms existing in nature. Water purification method. 18. The method according to claim 16, wherein treated raw water containing nitrite nitrogen or nitrate nitrogen is introduced into the cut-off area to remove nitrogen mainly by a denitrification reaction. Water purification method. 19. The process according to claim 18, wherein the treated raw water is obtained by purifying surface water containing phytoplankton generated in large amounts in the stagnant water area under aerobic conditions. Water purification method.