JP6499562B2 - Method and system for detoxifying hydrogen sulfide generated at the bottom of a lake or bay - Google Patents

Description

  The present invention relates to a method for detoxifying hydrogen sulfide generated at the bottom of a lake or the bottom of a bay using hematite produced by iron bacteria present in agricultural waterways, and a system thereof.

  For example, Lake Shinji in Shimane Prefecture is a brackish lake facing the Sea of Japan, and is famous for the production of Yamato Shijimi. Its output gradually decreased to 19,234 tons in 1973, the highest. In 2008, it decreased to 3,700 tons, but as of 2008, it accounted for 37% of Japan's total production, and is still the largest producer of Yamato Shijimi in Japan.

  The cause of the decrease in the production of Yamato Shijimi in Lake Shinji, which is a brackish water lake, can be thought of in various ways, but in combination with the geographical conditions where the ends of the surrounding rivers are located, the occurrence of blue tide due to eutrophication Is considered to be a cause. In September 2012, a large amount of fish such as sea bass, crucian carp, goby, etc. died on the west coast of Lake Shinji, and it is thought that blue tide was the cause. In addition, blue tide refers to things that occur in inner bays near cities such as Tokyo Bay, Osaka Bay, Mikawa Bay, etc., where there is little tide movement, and the surface water color appears to be pale blue from summer to autumn. Is recognized. The blue tide is a phenomenon that occurs when hydrogen sulfide formed in the bottom region of an anoxic state rises to the upper layer by a water flow and changes to particulate sulfur by contact with oxygen.

  In the case of a lake, not limited to Lake Shinji, in the case of a lake, domestic and industrial wastewater containing nutrients and organic substances flows through multiple rivers poured into the lake, eutrophication of the lake water, and nutrients are used as nutrient sources. Phytoplankton grows, and zooplankton also grows along with this. In both plankton, organic matter that became dead bodies and organic matter that flowed in from the outside remain deposited on the bottom of the lake because the microorganisms are inactive in winter when the water temperature is low. In brackish lakes such as Lake Shinji, the density difference between seawater and freshwater creates a density crest, also referred to as a fresh salt boundary, and keeps the seawater and freshwater separated. On the other hand, from spring to summer, it is the time when microorganisms become active, and by using the oxygen in the seawater to decompose organic matter deposited on the bottom of the lake, a large amount of dissolved oxygen around the bottom of the lake is consumed, Due to the presence of the density stratum, the lake water is not exchanged between the fresh water in the upper layer and the sea water in the lower layer, so that the bottom of the lake reaches an anoxic state or an oxygen-free state with a small amount of dissolved oxygen.

  At the bottom of the lake, which has become anaerobic / anoxic, the anaerobic sulfate-reducing bacteria instead of the aerobic microorganisms oxidize and decompose organic matter using sulfate ions in the lake water. It is reduced to hydrogen sulfide, increasing the hydrogen sulfide concentration at the bottom of the lake. For this reason, Yamatoshijimi inhabiting the shallow waters of the lake are damaged, and the anoxic / anoxic water mass at the bottom of the lake springs up to the upper layer due to strong wind in the area where the density stratum does not exist clearly. When raised, it may kill fish that exist along the way.

  Around 1955, algae shellfish and oysters were killed by hydrogen sulfide in Nakaumi, which is downstream of Lake Shinji. It was sprayed under the armpit to improve the survival rate. This is to reduce the concentration of hydrogen sulfide by reacting iron ions generated by the dissolution of “hematite” contained in red soil and hydrogen sulfide existing at the bottom of the lake to produce iron sulfide. Thus, hydrogen sulfide is rendered harmless to marine products such as algae and oysters.

  As another method of reducing the concentration of hydrogen sulfide generated in the brackish water bottom mud of the bay or brackish lake, artificially processed iron powder is sown in the brackish water bottom mud to react with hydrogen sulfide. It is already known that it becomes iron sulfide, and it has been confirmed that the soil is improved by sowing iron powder in an aging paddy field where hydrogen sulfide is generated. However, when this method of reducing hydrogen sulfide concentration is carried out on brackish water bottom mud, it is necessary to artificially process a large amount of iron powder, which requires a large amount of cost for processing a large amount of iron powder. At the same time, there is a problem that a lot of manpower and facilities are required for the work of sowing iron powder only in the brackish water bottom mud by preventing the iron powder from flowing to the surrounding watershed.

  In Patent Document 1, floating mud in an artificial bottom depression such as a channel is pumped together with seawater, sand removal treatment and aeration treatment are performed to improve mud, and the improvement mud is returned to the original artificial bottom depression. Then, ferric trioxide contained in the improved mud and hydrogen sulfide existing in the artificial water bottom depression are reacted to form iron sulfide, thereby reducing the amount of hydrogen sulfide in the artificial water bottom depression and generating blue tide. A technique for suppressing the above is disclosed. The technology disclosed in Patent Document 1 artificially forms a contact opportunity between iron ions and hydrogen sulfide existing in the sea, and reduces the hydrogen sulfide concentration in the artificial water bottom depression, so that In terms of detoxification, this is related to the detoxification measures for hydrogen sulfide in Nakaumi.

  On the other hand, there are iron bacteria that are a kind of soil microorganisms in nature, and they appear as red-brown or brown-brown precipitates or agar-like iron bacteria mud in general waterways including drainage channels for agriculture and drainage ditches. It has been known since ancient times to oxidize iron ions to produce oily iron oxide (hematite) in a stationary part where there is almost no water flow on the water surface. For example, if iron bacterial mud is generated over time in a narrow channel connected to a tunnel, the water channel is blocked, or excess iron bacterial mud leaks out on the track in the tunnel. Drugs that suppress mud generation have been developed (Patent Document 2). That is, conventionally, iron bacterial mud is often regarded as a useless or harmful substance, and the idea of actively utilizing the characteristics of the iron bacterial mud has not been found.

  There are many agricultural canals that flow into brackish lakes such as Lake Shinji, and the amount of iron bacterial mud (hematite) produced by the reaction of iron bacteria and iron ions in fresh water in the agricultural canal increases during rainfall. Then, the flow rate is higher than normal and poured into the brackish lake, but the iron bacterial mud is present in fresh water, so in the lake water, the water is in the fresh water area above the fresh salt boundary. Or it will float on the surface. Therefore, there is almost no chance that the iron bacterial mud that has been present in the freshwater area due to the inflow into the brackish lake will come into contact with the hydrogen sulfide existing at the bottom of the seawater area below the fresh salt boundary at the bottom of the lake. It can be said. It should be noted that among the fishermen, the iron bacterial mud flowing into the brackish lake and floating in the fresh water area is simply called “mud”.

  In particular, Shoji Hara and Ikuo Takeda have confirmed that the Izumo Plain located in the west of Lake Shinji (also referred to as “Yodogawa Plain”) has a high proportion of iron in groundwater. Based on that information, Shoichiro Inoue, the joint inventor of the present application, said that the iron bacterial mud in the agricultural canal of the Izumo Plain contains 370 g / kg of iron, which is much higher than usual. The result of the analysis was confirmed. In addition, the collaborative inventor of this application, Akira Ueno, researched latent sulfate soil, and pyrite (pyrite) in the soil was subjected to the action of iron and sulfuric acid bacteria, resulting in hematite (hematite) and sulfuric acid. Report changes.

  In addition, as described above, brackish lakes such as Lake Shinji do not exchange lake water between upper fresh water and lower sea water due to the presence of the density stratum, and hydrogen sulfide that causes blue tide is It is known that it is concentrated in the area near the lake bottom in the large lower layer of seawater.

Japanese Patent No. 4842781 JP-A-10-54721

  Based on the above findings, the present invention introduces muddy water containing natural hematite produced by the action of iron bacteria present in agricultural waterways into the seawater part of the lower layer of the density crest. The challenge is to reduce the concentration of hydrogen sulfide by artificially creating contact opportunities between iron ore and hydrogen sulfide and reacting both.

The invention of claim 1 for solving the above-mentioned problem is a method for detoxifying hydrogen sulfide existing at the bottom of a lake or at the bottom of a bay using hematite produced by iron bacteria present in an agricultural waterway,
The mud containing hematite in the agricultural waterway is stored in a mud storage tank installed in a portion close to a lake or bay, and the mud is stored while maintaining the non-precipitation state of the hematite,
The muddy water is discharged to the bottom of the lake or the bay by the action of a pump, and hematite contained in the muddy water reacts with hydrogen sulfide existing in the bottom of the lake or the bay to sulfidize the bottom of the lake or the bay. It is characterized by reducing the hydrogen concentration.

  Iron dissolved in groundwater is in the form of divalent iron ions, and forms iron-shelled shells of iron hydroxide by the action of iron bacteria existing in the natural world such as agricultural waterways to become sheath-shaped hematite. [It exists as iron (Kanake)] is known, and in the waterway for agriculture, pod-like hematite is contained in the mud. Shoichiro Inoue, co-inventor of the present application, said that the muddy water containing the scabbard hematite has a specific gravity (about 1.03) that is equivalent to seawater. When it is discharged to the bottom or the bay bottom, a chemical reaction occurs between the sheathed hematite contained in the mud and the hydrogen sulfide generated at the bottom of the lake or the bottom of the bay, thereby generating iron sulfide. It came to the idea to reduce the hydrogen sulfide concentration at the bottom of the bay. Here, the muddy water containing scabbard hematite is separated in specific gravity from the supernatant water due to sedimentation of the mud containing hematite in a relatively short time, and includes hematite using pipes, hoses, etc. It is difficult to send mud. For this reason, the muddy water containing scabbard hematite needs to be kept almost uniformly cloudy over a long period of time. In the invention of claim 1, as this means, as a peptizer in the ceramic industry. By adding the sodium silicate (water glass) used to the mud containing hematite, the specific gravity separation of the mud containing hematite during storage is prevented and the fluidity is increased, Ensuring ease of mud feeding with hose etc.

  Therefore, when sodium silicate is added to the mud in the agricultural canal and stored in the mud tank, the mud is discharged to the bottom of the lake or the bay using pipes, hoses, etc. Since the mud has the same specific gravity as seawater, the mud containing hematite does not rise and stays at the bottom of the lake or the bay as it is. Because of the increased fluidity of the mud, the mud is not settled only at the place where it was released, and if there is a water flow at the bottom of the lake or the bay, Sprayed on. As a result, iron sulfide is generated by the reaction of hematite contained in the muddy water and hydrogen sulfide generated and present at the bottom of the lake or the bay. By reducing the hydrogen concentration, the green tide environment by eutrophication is improved, and the environment is transformed into a favorable environment for aquatic products.

  On the other hand, when muddy water containing sodium silicate mixed as a peptizer containing hematite is supplied to the bottom of the brackish lake or the bottom of the bay, silicon will be supplied to the diatoms present in the brackish water In addition, the silicon deficiency of diatoms has been resolved, food is stably secured for shellfish such as Yamatojimi, clams and fish that feed on diatoms, and sodium silicate supplied to brackish water is Harmless to shellfish and fish.

The invention of claim 2 is a method for detoxifying hydrogen sulfide present at the bottom of a lake or at the bottom of a bay using hematite produced by iron bacteria present in an agricultural waterway,
Storing mud containing hematite in the agricultural canal in a mud tank installed near a lake or bay;
The muddy water is discharged to the bottom of the lake or the bay by the action of a pump, and hematite contained in the muddy water reacts with hydrogen sulfide existing in the bottom of the lake or the bay to sulfidize the bottom of the lake or the bay. It is characterized by reducing the hydrogen concentration.

  In the invention of claim 1, if discharge of mud containing hematite is possible by using a hematite produced by iron bacteria present in agricultural waterways without using sodium silicate, It is possible to detoxify the hydrogen sulfide present at the bottom of the bay, and claim 2 is the invention according to claim 1 when sodium silicate is not used.

  The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the mud water is stirred in the mud tank before the mud water in the mud tank is discharged and discharged immediately thereafter.

  In invention of Claim 1 or 2, the mud which has settled in the bottom part and the part of the upper supernatant water are mixed by stirring the muddy water before discharge | release in a mud tank, and hematite is included. It becomes easy to discharge muddy water.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the lake is a brackish lake, and the muddy water containing hematite is supplied to the lower portion of the fresh salt boundary between the fresh water and sea water. It is characterized by being discharged using it.

  According to the invention of claim 4, when the discharge destination of the muddy water containing hematite is a brackish lake, the muddy water containing hematite discharged to a portion slightly lower than the density flow is composed of fresh water and seawater. Due to the action of the density current flowing at the boundary, it spreads over a wide part of the brackish lake and settles at the bottom of the lake, so that the effect of hematite scattering increases, making hydrogen sulfide harmless over a wide area of the brackish lake. It becomes possible.

  In addition, as described in paragraph “0010”, iron bacterial mud (hematite) generated in agricultural canals poured into brackish lakes is contained in fresh water, so after being poured into brackish lakes However, it will continue to exist in the freshwater area above the fresh salt boundary, so that it will not reach the bottom of the lake where hydrogen sulfide is generated (the bottom of the seawater area), and hydrogen sulfide and hematite will come into contact with each other. Although there is almost no opportunity for reaction, according to the invention of claim 4, mud water containing hematite is discharged into the portion below the fresh salt boundary between fresh water and sea water using density flow. In this area, iron bacterial mud (hematite) does not float and stays in the bottom of the lake, which is a seawater area. It reacts with hydrogen sulfide existing in the bottom of the lake to form iron sulfide, which is sulfided at the bottom of the lake. Hydrogen concentration is reduced.

  A fifth aspect of the present invention is characterized in that, in the invention of the fourth aspect, the brackish lake is a Shinji lake in Shimane Prefecture, and the place where the muddy water is discharged is near the mouth of the Hii River.

  As described in the paragraph “0011”, the Izumo Plain located in the west of Lake Shinji is known to have a high proportion of iron contained in groundwater, and in the muddy water of agricultural waterways flowing through this Izumo Plain, It will contain more hematite than the outside area, and the area around the mouth of the Hirai River that flows through the Izumo Plain is also a place where Yamato Shijimi is abundantly produced. Therefore, as in the invention of claim 5, when muddy water containing hematite is discharged to the vicinity of the mouth of the Hii River, the effect of detoxifying hydrogen sulfide in the hydrogen sulfide generation region existing at the bottom of the lake near the mouth of the river is increased. , The productivity of Yamatoshijimi living on the bottom of the lake is increased.

  The invention of claim 6 is the invention according to any one of claims 1 to 5, wherein the lake water having a large specific gravity in the sea area below the fresh salt boundary of the brackish lake is returned to the mud tank, and the water is stored through the agricultural waterway. It is characterized by being discharged into a brackish lake in a state mixed with muddy water containing hematite flowing into the mud tank.

  According to the invention of claim 6, the mud containing the hematite discharged to the brackish lake contains the lake water in the sea area below the fresh salt boundary having a larger specific gravity than the fresh water. Is much larger than fresh water, so the time to stay at the bottom of the lake becomes longer and the chance of contact with hydrogen sulfide becomes larger, or the contact time becomes longer and the concentration of hydrogen sulfide is increased. Decrease is promoted.

The invention of claim 7 is a system for carrying out the invention of claim 1,
In order to store mud containing hematite in the agricultural channel, a mud tank installed in a portion near a lake or bay,
In order to supply a predetermined amount of sodium silicate to the mud stored in the mud tank, a sodium silicate supply device attached to the mud tank;
In order to send mud containing hematite to the lake bottom or the bay bottom, a base end is connected to the mud tank, and a mud feed pipe disposed along the coast of the lake or bay,
A number of branch hoses branched from the mud pipe and having a tip reaching the bottom of the lake or the bay,
A mud feeding pump for sucking mud water added with sodium silicate in the mud storage tank and sending it to the lake bottom or the bay bottom through the mud feeding pipe;
It is characterized by having.

  According to the seventh aspect of the present invention, the most downstream end of the agricultural waterway is connected to the mud storage tank installed near the lake or the bay, and mud containing hematite is always infused and stored. When discharging mud containing hematite, sodium silicate is added to the mud from the sodium silicate feeder. On the coast of the lake or bay where hydrogen sulfide may be generated, mud pipes are arranged along the coast, and the tip of a number of branch pipes branched from the mud pipe is the bottom of the lake. Alternatively, the muddy water containing hematite added with sodium silicate is discharged to the lake bottom or the bay bottom via the mud pipe and the branch pipe by the suction action of the mud pump that has reached the bottom of the bay.

  The invention of claim 8 is characterized in that, in the invention of claim 7, a stirrer for stirring the mud in the mud tank is provided.

  According to the invention of claim 8, when the mud containing the hematite stored in the mud tank is stirred by the stirrer immediately before the discharge of the mud containing the hematite, the mud portion precipitated in the lower part, By mixing with the upper supernatant water, the whole becomes almost uniform concentration, and the mud containing hematite is not stored in the bottom of the mud tank, and the mud is stored in the mud tank. Muddy water can be discharged.

  The invention according to claim 9 is the invention according to claim 7 or 8, wherein the lake is a brackish lake, and the tip of the branch hose is disposed in a portion below the density flow flowing at the boundary between fresh water and seawater. It is characterized by being.

  In the part of the brackish lake connected to the river, due to the density difference between fresh water and seawater, a density flow is generated at the boundary between the two waters. The muddy water containing hematite discharged from the branch hose is diffused extensively by being flown far away by the flow of the density flow, and settles on the lake bottom. Therefore, the range in which hydrogen sulfide can be rendered harmless is expanded by using a density flow that is a natural water flow.

  The present invention is a method for adding muddy water containing natural hematite existing in agricultural waterways and the like to a storage tank installed in a portion near a lake or a bay, as required, by adding sodium silicate. The mud is stored in a non-precipitated state, and the mud is discharged to the bottom of the lake or the bay by the action of the pump, that is, the muddy water containing hematite produced in nature by the action of iron bacteria is removed from the pump. It is discharged to the bottom of the lake or the bay by the action, artificially creating an opportunity for contact between the hematite contained in the mud and the hydrogen sulfide existing at the bottom of the lake or the bay, Or hydrogen sulfide is made harmless by reducing the hydrogen sulfide concentration at the bottom of the bay. In this way, iron is produced artificially by discharging the muddy water to the bottom of the lake or the bay by the action of the pump in the natural state with the hematite produced in nature in the muddy water. Or remove large amounts of red soil containing hematite, remove pump power, and discharge hematite naturally generated in agricultural waterways etc. into the muddy water, and discharge it to the bottom of the lake or bay By doing so, hydrogen sulfide existing at the bottom of the lake or the bay can be rendered harmless, and therefore, a small number of facilities for implementation are required and the implementation can be performed at low cost.

  In addition, when the discharge destination is a brackish lake, it is possible to diffuse mud containing hematite widely with no power by flowing muddy water containing hematite using density flow, The range in which hydrogen sulfide can be rendered harmless is expanded. Furthermore, by adding sodium silicate before the discharge of the mud containing hematite, the non-precipitation state of the hematite in the mud can be maintained, and the discharge of the mud becomes easy. It contributes to the supply of silicon that lacks diatoms present in freshwater and seawater, and is harmless to marine organisms such as shellfish and fish, so it does not harm the lake water environment or the bay water environment.

1 is a schematic plan view of a lake bottom detoxification system using hematite produced in an agricultural waterway according to the present invention. It is a typical sectional view similarly. It is a top view of the mud storage tank A containing a hematite. It is sectional drawing similarly. FIG. 4 is a view taken in the direction of arrow X in FIG. 3. (A), (b) is the top view of the stirrer M installed in the mud storage tank A, respectively, and a front view. (A), (b) is the top view of the sodium silicate supply tower E installed in the mud storage tank A, respectively, and a front view. FIG. 3 is a schematic cross-sectional view showing the principle of discharging mud water W ₀ using a density flow D. Back lake large seawater W ₂ of the specific gravity (seawater) to貯泥tank A, is a schematic plan view of a system for increasing the specific gravity of the mud W ₀ to discharge.

  FIGS. 1 and 2 are a schematic plan view and a schematic cross-sectional view of a hydrogen sulfide detoxification system according to the present invention on the west coast of Lake Shinji in Shimane Prefecture. As mentioned in the “Background Technology” section, Lake Shinji has the largest production of Yamatoshijimi in Japan, but its production has been decreasing year by year, and it is also sulphurized due to anoxic conditions. There is also a lake bottom where hydrogen is generated, which worsens the growth environment of yamatoshijimi, and the Izumo Plain, located west of Lake Shinji, has a higher proportion of iron in groundwater than in normal areas. The iron bacterial mud in the agricultural canals in the paddy field area of the Izumo Plain contains 370 g / kg of iron, which is much higher than usual, so the red produced by iron bacteria in the mud Due to the high content of iron ore, the west coast of Lake Shinji is an area where the implementation of the present invention is strongly desired.

The plain portion outside the levee 61 of Lake Shinji is lower than the lake surface, and mud water (mud flowing in the irrigation canal 62 in the most downstream portion of the relatively large agricultural canal 62 in the plain close to the levee 61貯泥tank a is provided for storing water) W ₀ containing part. The agricultural water channel 62 may be a single water channel with a relatively wide water volume formed in an actual rice field. When the water channel width is narrow, a plurality of water channels flowing in close proximity are joined together. It is desirable to secure the required amount of water by forming them. The shape of the mud storage tank A is arbitrarily determined in relation to the surrounding topography, but in the schematic diagram, it is rectangular. A portion of the square-shaped peripheral wall 1 of the mud storage tank A connected to the agricultural water channel 62 is formed with a rectangular inlet 2 corresponding to the width of the agricultural water channel 62. The mud water in the agricultural water channel 62 always flows in from 2 and the capacity of the mud tank A is exceeded by the action of the mud pump P ₁ until the mud water W ₀ stored in the mud tank A is discharged to the bottom of the lake. When muddy water flows in, the supernatant water generated by the sedimentation of the mud is discharged to the outside through a cough 3 provided in an arbitrary part of the peripheral wall 1 of the mud tank A and passed through the supernatant water drainage channel 63. It is structured to flow through the river closest to the mud tank A. 1 to 4, the cough 3 is formed at one place on the peripheral wall 1 parallel to the inflow direction of the mud water W ₀ from the agricultural water channel 62 to the mud tank A.

Mud containing hematite stored in the mud storage tank A is branched from the mud pipes Qa and Qb and the mud pipe Qb by the action of the mud pump P ₁ and is arranged in the lake water. It is discharged to the bottom of the lake near the lake shore through the hose Qc. The mud pipe Qa is a part that is routed between the storage tank A and the lake shore across the bank 61, and the mud pipe Qb is branched from the single mud pipe Qa to both sides, It is a part piped along. Each of the above-described mud feeding pipes Qa and Qb and the branch hose Qc may be exposed pipes, but it is desirable to embed them underground from the viewpoint of landscape maintenance and prevention of contact accidents. Further, in a brackish lake Shinjiko, in almost the entire, seawater W ₂ below the freshwater W ₁ exists separated in the depth direction, the boundary of the two waters W _1, W ₂ is Awashio boundary mud has become is B, the present invention is included in the specific gravity than freshwater W ₁ is large, the seawater W ₂ which is located below the freshwater W _1, the hematite generated in nature Is released as it is, artificially forming contact opportunities between hydrogen sulfide and hematite existing at the bottom of the lake, and reacting both to form iron sulfide, thereby reducing the concentration of hydrogen sulfide. Specifically, the mud water W ₀ containing hematite stored in the mud tank A is sucked from the mud tank A by the power of the mud pump P ₁ , regularly to be released into the seawater W ₂ parts. In FIG. 1, W ₁₀ indicates a lake part of the brackish lake, and 64 indicates a boundary line between the lake part and the lake shore part.

Of the mud water W ₀ containing hematite stored in the mud storage tank A, the mud containing hematite is separated by specific gravity with the passage of time and settles to the bottom of the mud tank A, and the upper part is mud. In order to obtain supernatant water that does not contain water, the fluidity (mud-feeding performance) in the above-described mud-feeding pipes Qa and Qb and the branch hose Qc is ensured so that mud is uniformly contained throughout the discharge. Need to increase. For this reason, as shown in FIGS. 3 to 6, a plurality of agitators M are installed inside the mud tank A, and the agitator M is operated immediately before the mud water stored in the mud tank A is discharged. Further, the fluidity (mud-feeding property) of the mud water in the mud-feeding pipes Qa, Qb and the branch hose Qc is improved by uniformly dispersing the mud containing hematite in the mud-water.

The stirrer M may be of any structure as long as the mud content in the mud can be uniformly dispersed. For example, as shown in FIG. A bearing portion 14 is integrally provided directly below the upper support plate 13 of the frame-shaped frame 12, and the upper end portion of the vertical rotating shaft 15 is cantilevered by the bearing portion 14. A first reduction gear 16 attached to a portion protruding upward, and a second reduction gear attached to the drive shaft 17a of the motor 17 supported on a motor support frame (not shown) with the drive shaft 17a downward. By meshing with the gear 18, the vertical rotation shaft 15 is driven and rotated by the driving force of the motor 17. A plurality of stirring blades 19 are integrally attached to the vertical rotating shaft 15, and when the vertical rotating shafts 15 of the plurality of stirrers M are driven and rotated, the hematite with mud precipitated on the bottom by the rotation of the plurality of stirring blades 19. The mud containing water is agitated and the mud is mixed with the muddy water W ₀ immediately before the discharge. In FIG. 6, 20 indicates a roof plate that covers the motor 17 and the gears 16 and 18, and 4 indicates the bottom wall of the mud tank A.

On the other hand, sodium silicate (water glass) is used as a peptizer in the ceramics field, and by adding the sodium silicate to the mud containing hematite, the specific gravity separation of hematite containing hematite during storage When the mud water W ₀ containing hematite in the mud is fed using the above-described mud feeding pipes Qa and Qb and the branch hose Qc, the fluidity is improved and the fluidity is enhanced. In combination with the stirring action of the mud water W ₀ by the plurality of stirrers M, the mud feeding ability of the mud water W ₀ is enhanced and the mud can be smoothly fed.

  For this reason, the sodium silicate supply tower E is installed in the upstream of the mud tank A (side near the agricultural water channel 62). In other words, a circular supply tower insertion hole 34 is formed at the center of the horizontal support plate 33 formed of four support columns 31 and in the upper part of the square frame 32 in plan view, and the cylinder of the sodium silicate supply tower E The sodium silicate supply tower E is attached to the frame 32 by supporting a plurality of brackets 35 attached to the upper surface of the horizontal support plate 33 and fixing both the bolts 33 and 35 with bolts.

Supply of sodium silicate for muddy water reserved in the貯泥tank A, immediately before discharge of the mud, and stirring the mud W ₀ being gravity separation by a plurality of agitator M, in the mud W _0, hematite Is carried out after the mud part containing water is uniformly dispersed, the specific gravity separation of the mud water W ₀ is suppressed by the peptization of sodium silicate, and the mud part is uniformly dispersed in the mud water W ₀ . The muddy water W ₀ can be discharged into the lake water.

While mud W ₀ is above the貯泥tank A, by the action of Okudoro pump P _1, Okudoro pipe Qa, through Qb and branched hose Qc, muddy water W ₀ reserved in the貯泥tank A, shores To the sea area W ₂ at the bottom of the lake near the lake. Here, when the fresh water of the agricultural water channel 62 is poured into the brackish lake as it is, the mud water W ₀ containing hematite, which is fresh water, stays in the fresh water area W ₁ above the fresh salt boundary B. In the seawater area W ₂ , it does not react with hydrogen sulfide at the bottom of the lake, but the muddy water W ₀ has a specific gravity (1.02 to 1.03) equivalent to seawater. the presence of Awashio boundary B, retention for lake exchange is not performed between the upper layer of freshwater W ₁ and a lower seawater W _2, without mud content including hematite floats, as it is to the bottom of the lake At the same time, the fluidity of the mud water W ₀ containing hematite has increased due to the peptization of sodium silicate, so that the mud water W ₀ does not sink to the location where it was discharged, but flows into the lake bottom. Is generated, it is spread over a wide area by the water flow. As a result, hematite contained in the mud water W ₀ reacts with hydrogen sulfide generated and present at the bottom of the lake to produce iron sulfide, and the hydrogen sulfide concentration at the bottom of the lake is reduced. Thus, the green tide environment due to eutrophication is improved, and the environment is transformed into a favorable environment for aquatic products, particularly Yamato Shijimi that live only on the bottom of the lake. 6 and 7 indicate the water surface S of the mud water W ₀ stored in the mud storage tank A.

  The muddy water containing hematite discharged from the tip of the branch hose Qc is discharged to the bottom of the shallow water where Yamatoshijimi is most likely to live in brackish lakes including Lake Shinji. As the concentration of hydrogen sulfide is reduced, the degree of improvement in the habitat of Yamatoshijimi increases.

  On the other hand, when the muddy water containing sodium silicate mixed as a peptizer containing hematite is supplied to the bottom of the brackish lake, silicon is supplied to the diatom present in the brackish water, The shortage of silicon is resolved, and food is stably secured against shellfish such as Yamatoshijimi, clams and fish that feed on diatoms. In addition, sodium silicate supplied to brackish water is harmless to shellfish and fish.

On the west coast of Lake Shinji, there is the Hii River as a large river that flows into Lake Shinji. At the estuary, a fresh salt boundary B is formed between the fresh water area W ₁ and the sea water area W _2, and the river Due to the flow of fresh water from the seawater, a phenomenon called “density flow” occurs in which the fresh water in the upper layer and the seawater in the lower layer flow independently from each other at the fresh salt boundary B. When it is discharged muddy water W ₀ of the above lake portion of the mouth of the river, by the action of "Density flow" of the mud W ₀ which is discharged into lake section, above the freshwater W ₁ than Awashio boundary B Without being flowed into the seawater, it remains in the seawater area W ₂ and is further discharged to the periphery by the “density flow”, so that the discharge area of the mud water W ₀ becomes wider and the area where the hydrogen sulfide concentration is reduced becomes wider.

For example, as shown in FIG. 8, the main pile 41 is driven into the river mouth at a predetermined interval along the river width direction, and the downstream side of the main pile 41 is supported by the support pile 42. Supporting, arranging the mud pipe Qb on the upstream side of the plurality of main piles 41, binding and fixing to the main pile 41, connecting the branch hose Qc to the main pile 41 at a predetermined interval, This can be realized by discharging the muddy water W ₀ from the branch hose Qc into the seawater area W ₂ where the “density flow D” is generated.

In brackish lakes such as Lake Shinji, back of seawater W ₂ lake water (the sea) in貯泥tank A, by increasing the specific gravity of the mud W ₀ which discharged into the lake, often the generation of hydrogen sulfide lakebed It is possible to lengthen the time during which the mud water W ₀ stays in the part, and to increase the efficiency of detoxifying hydrogen sulfide.

FIG. 9 is a schematic plan view of a system for carrying out the above technique, and in parallel with a pipe portion in which a mud feeding pump P ₁ is incorporated in a portion near the mud storage tank A in the mud feeding pipe Qa, The reverse flow pump P ₂ is incorporated, and the mud pipe Qa intersects with the pipe portion where the reverse flow pump P ₂ is incorporated and a branch portion, and the mud pipe Qb piped in parallel with the boundary line 64 between the lake water portion and the lake shore portion. The three-way valves V ₁ and V ₂ are respectively incorporated in the parts that perform the operation, and the on-off valve V ₃ is provided in the mud pipe Qb so that one branch hose Qc exists between the three-way valve V _2. It has been incorporated.

Therefore, at the time of discharge of the mud W ₀ of貯泥tank A, muddy water W ₀ discharged from Okudoro pump P ₁ is, through the Okudoro pipe Qa, is branched to each Okudoro pipe Qb both sides at its end As described above, the three-way valves V ₁ and V ₂ are switched, and the on-off valve V _{3 is set} to “open”, so that the mud storage pump A sucks and discharges mud water W ₀ in the mud tank A by the mud pump P _1. The muddy water W _{0 in the} tank A is discharged into the lake water through a plurality of branch hoses Qc.

On the other hand, when returning the lake water (seawater) in the seawater area W ₂ to the mud tank A and increasing the specific gravity of the mud water W ₀ discharged into the lake water, the seawater area sucked by a specific single branch hose Qc The three-way valves V ₁ and V ₂ are switched and the on-off valve V _{3 is set} to “closed” so that the lake water of W ₂ is returned to the mud tank A through the paths indicated by the arrows in FIG. This is realized.

In particular, on the west coast of Lake Shinji, mud tank A is installed in the lower part of the lake surface, so the water level difference H between the lake water surface and mud tank A (see FIG. 2) is a reverse flow pump. When the lake water (seawater) in the seawater area W ₂ is sucked by P ₂ , and the lake water is made to flow back through the specific one branch hose Qc and each of the mud pipes Qb and Qa and returned to the storage tank A Since the “siphon function” is achieved, the reverse flow of the lake water is facilitated, and the power of the reverse flow pump P ₂ can be reduced.

  In addition to Lake Shinji, the object of implementation of the present invention is not only a brackish lake with the occurrence of hydrogen sulfide at the bottom of the lake or its fear, but also a bay where shellfish such as swordfish and bivalve inhabit by the presence of brackish water, Alternatively, the present invention can be applied to the estuary of a large river, and the present invention can be applied to a bay or a estuary of a large river by storing and discharging mud containing iron bacterial mud from a nearby agricultural channel. Can be implemented.

  As described above, the present invention discharges muddy water containing hematite produced in nature to the seawater area at the bottom of the lake by the action of the mud pump in the natural state of flowing through agricultural waterways and the like. In order to eliminate mud water containing hematite naturally generated in agricultural waterways, etc., without pumping power, without artificially processing iron or carrying a large amount of red soil containing hematite, etc. By discharging it to the bottom of the lake or the bay, hydrogen sulfide existing at the bottom of the lake or the bay can be rendered harmless, so that it requires less facilities for implementation and can be carried out at a low cost. In particular, when the present invention is applied to Lake Shinji in Shimane Prefecture, the ratio of the hematite contained in the mud flowing in the agricultural waterways and the like is that the groundwater in the surrounding plains contains more iron than in other areas. When hydrogen sulfide is generated at the bottom of the lake, combined with the fact that it is higher than in other areas, the concentration is effectively reduced, so that the habitats for shellfish such as Yamatoshijimi and fish As a result, the production volume of Yamatoshijimi, which is currently the best in Japan, can be expected to increase further.

A: Mud tank
B: Fresh salt boundary
D: Density flow
E: Sodium silicate supply tower
H: Water level difference
M: Stirrer
P _1: Okudoro pump
P ₂ : Backflow pump Qa, Qb: Mud pipe
Qc: Branch hose
S: Mud water level in the mud tank V ₁ , V ₂ : Three-way valve
V _3: opening and closing valve
W ₀ : Mud containing hematite
W ₁ : Freshwater area
W ₂ : Seawater area
W _10: Lake section
62: Agricultural waterway

Claims (9)

A method of detoxifying hydrogen sulfide existing at the bottom of a lake or bay using hematite produced by iron bacteria present in an agricultural waterway,
The mud containing hematite in the agricultural waterway is stored in a mud storage tank installed in a portion close to a lake or bay, and the mud is stored while maintaining the non-precipitation state of the hematite,
The muddy water is discharged to the bottom of the lake or the bay by the action of a pump, and hematite contained in the muddy water reacts with hydrogen sulfide existing in the bottom of the lake or the bay to sulfidize the bottom of the lake or the bay. A method for detoxifying hydrogen sulfide generated at the bottom of a lake or at the bottom of a bay, wherein the hydrogen concentration is reduced. A method of detoxifying hydrogen sulfide existing at the bottom of a lake or bay using hematite produced by iron bacteria present in an agricultural waterway,
Storing mud containing hematite in the agricultural canal in a mud tank installed near a lake or bay;
The muddy water is discharged to the bottom of the lake or the bay by the action of a pump, and hematite contained in the muddy water reacts with hydrogen sulfide existing in the bottom of the lake or the bay to sulfidize the bottom of the lake or the bay. A method for detoxifying hydrogen sulfide generated at the bottom of a lake or at the bottom of a bay, wherein the hydrogen concentration is reduced.   The sulfidation generated at the bottom of a lake or at the bottom of a bay according to claim 1 or 2, wherein the mud is stirred in the mud before the mud is discharged in the mud, and immediately after that. Hydrogen detoxification method.   4. The lake according to claim 1, wherein the lake is a brackish lake, and muddy water containing hematite is discharged using a density flow in a portion below a fresh salt boundary between fresh water and sea water. A method for detoxifying hydrogen sulfide generated at the bottom of a lake or the bottom of a bay.   The brackish lake is Shinji Lake in Shimane Prefecture, and the place where the muddy water is discharged is in the vicinity of the mouth of the Hii River. The hydrogen sulfide generated at the bottom of the lake or bay according to claim 4, Detoxification method.   The lake water with a high specific gravity in the sea area below the brackish lake fresh salt boundary is returned to the mud tank and mixed with mud containing hematite flowing into the mud tank through the agricultural canal. The method for detoxifying hydrogen sulfide generated at the bottom of a lake or at the bottom of a bay according to any one of claims 1 to 5, characterized in that it is discharged. A system for carrying out the invention according to claim 1,
In order to store mud containing hematite in the agricultural channel, a mud tank installed in a portion near a lake or bay,
In order to supply a predetermined amount of sodium silicate to the mud stored in the mud tank, a sodium silicate supply device attached to the mud tank;
In order to send mud containing hematite to the lake bottom or the bay bottom, a base end is connected to the mud tank, and a mud feed pipe disposed along the coast of the lake or bay,
A number of branch hoses branched from the mud pipe and having a tip reaching the bottom of the lake or the bay,
A mud feeding pump for sucking mud water added with sodium silicate in the mud storage tank and sending it to the lake bottom or the bay bottom through the mud feeding pipe;
A detoxification system for hydrogen sulfide generated at the bottom of a lake or at the bottom of a bay.   The system for detoxifying hydrogen sulfide generated at the bottom of a lake or at the bottom of a bay according to claim 7, further comprising a stirrer for stirring the mud in the mud storage tank.   The lake bottom according to claim 7 or 8, wherein the lake is a brackish lake, and a tip end portion of the branch hose is disposed in a portion below a density flow flowing at a boundary between fresh water and sea water. Detoxification system for hydrogen sulfide generated at the sea or bay bottom.

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