JP6607440B2 - Constructed wetland for water quality improvement - Google Patents

Description

  The present invention relates to an artificial wetland for improving water quality.

  Organic matter and nutrients contained in domestic wastewater, agricultural wastewater, livestock wastewater, industrial wastewater, etc., are collected as BOD (Biochemical Oxygen Demand) and treated water with reduced nitrogen components using the decomposition action of microorganisms. Is called.

  In Patent Document 1, as an artificial wetland for improving water quality, a plurality of filter beds on which biofilms or plant rhizosphere microorganisms are formed are layered, and an inter-filter bed is provided between the layered filter beds. Stated to supply air to the floor.

  Non-Patent Document 1 points out that in an environment where water is present in an artificial wetland, oxygen concentration is insufficient and the biological aerobic degradation action is rate-determined. As a model of natural phenomena that can overcome this, Describes the tides. In tidal flats, there are regular periods of time during which the water level drops at low tide, the sediment is exposed, and oxygen is supplied directly from the atmosphere without water. As a result, in the tidal flat, organic matter and nutrients flow in and sink during the time when the water level rises due to the rising tide, and they are decomposed during the time when the water level falls due to the lower tide.

JP, 2014-231042, A

Nakano, Limitation and application of the purification function of natural ecosystems-Case study of artificial wetland-Journal of Environmental Biotechnology, Vol. 10, no. 2, 2010, p53-57

  In a natural tidal flat, the period during which the tidal flat sand absorbs and exhausts air is about 6 hours of the tidal cycle. In contrast, in artificial wetlands for improving water quality, the types and concentrations of organic matter and nutrients contained in the wastewater to be treated, the types of biofilms and plant rhizosphere microorganisms formed on the filter media of artificial tidal flats, Depending on the density and the like, the processing time required to reduce BOD and nitrogen components varies. If the water level of the filter medium is changed and the cycle of the water level change can be set according to the purpose, it is possible to efficiently reduce BOD and nitrogen components using a tidal flat tidal model in an artificial wetland.

  An object of the present invention is to provide an artificial wetland for improving water quality that can vary the water level of a filter medium. Another object is to provide an artificial wetland for improving water quality in which the period of fluctuation of the water level of the filter medium can be set according to the purpose. The following means contribute to achieving at least one of these objectives.

The artificial wetland for improving water quality according to the present invention is an artificial wetland for improving water quality that utilizes the decomposition action of microorganisms on organic matter and nutrients, and has a predetermined filter medium thickness formed with a biofilm or a plant rhizosphere microorganism group. and artificial tidal filter bed Ru Tei top portion and the peripheral wall portion includes a filter medium and a bottom portion is formed in the waterproof structure is opened to the atmosphere side with the water to be treated to the filter medium of the artificial tidal filter bed containing an organic substance and nutrients A water supply unit that supplies water, a drainage unit that drains treated water that has been decomposed to the outside of the waterproof structure of the artificial tidal flat filter bed, and fluctuates the water level in the artificial tidal flat filter bed with a predetermined breathing period cycle. The fresh air is sucked into the filter medium from the atmosphere side during the period when the treated water is drained, and the air that has been decomposed during the period during which the water to be treated is permeated into the filter medium is released from the filter medium to the atmosphere. Comprising a filter medium breathing mechanism for the gas, the filter medium breathing mechanism has a water absorption portion which absorbs water predetermined water level measured from the reference position of the bottom surface of the waterproof structure whereas the edge, drainage of low water side of the water level A siphon tube mechanism that has a drainage part that drains at the water level at the other end, and a part of the pipe line connecting the water absorption part and the drainage part is arranged at a height position of the operation reference water level higher than the water absorption water level, The respiration period cycle can be adjusted by setting three conditions: the filter medium volume of the filter medium of the artificial tidal flat, the water penetration rate in the filter medium, and the operation reference water level of the siphon tube mechanism. the larger, the more slow permeation rate, the higher the operating reference level, the respiratory period period is characterized Rukoto be set longer.

The artificial wetland for improving water quality according to the present invention is an artificial wetland for improving water quality that utilizes the decomposition action of microorganisms on organic matter and nutrients, and has a predetermined filter medium thickness formed with a biofilm or a plant rhizosphere microorganism group. An artificial tidal flat filter bed that includes a filter medium having a peripheral wall portion and a bottom surface portion that is formed with a waterproof structure and has an upper surface portion that is open to the atmosphere, and water to be treated that contains organic matter and nutrient salts is added to the filter medium of the artificial tidal flat filter bed. A water supply unit that supplies water, a drainage unit that drains treated water that has been decomposed to the outside of the waterproof structure of the artificial tidal flat filter bed, and fluctuates the water level in the artificial tidal flat filter bed with a predetermined breathing period cycle. The fresh air is sucked into the filter medium from the atmosphere side during the period when the treated water is drained, and the air that has been decomposed during the period during which the water to be treated is permeated into the filter medium is released from the filter medium to the atmosphere. Comprising a filter medium breathing mechanism for the gas, the filter medium breathing mechanism has a water absorption portion which absorbs water predetermined water level measured from the reference position of the bottom surface of the waterproof structure whereas the edge, drainage of low water side of the water level A drainage part that drains at the water level is provided at the other end, and the pipe line connecting the water absorption part and the drainage part is shut off until the water level of the water to be treated that has permeated the filter medium reaches the predetermined operation reference water level. conduit check opening mechanism der comprising a water level open check valve the water level to open the conduit portion connecting reaches the operating reference level and the water absorption portion and the drain portion of the is, the breathing period cycle, artificial tidal filtration It can be adjusted by setting three conditions: the filter medium volume of the filter medium on the floor, the water permeation rate in the filter medium, and the operation reference water level of the pipe check release mechanism. The other conditions are the same. The slower the speed, the higher the operating reference water level, Ku can be set and said Rukoto.

In the artificial wetland for improving water quality according to the present invention, in order to set the respiration period cycle of two artificial tidal flat filter beds having the same infiltration rate and different filter medium volumes, the artificial tidal flat filter bed having a smaller filter medium volume is used. than the operating reference level, Rukoto to set high an operation reference water level of the artificial tidal filter bed towards the filter media volume is large are preferred.

In the artificial wetland for improving water quality according to the present invention, with respect to the two artificial tidal flat filter beds having different infiltration rates with the same operation reference water level, the infiltration rate is higher than the breathing period cycle of the artificial tidal flat filter bed having a higher infiltration rate. The respiration period cycle of the artificial tidal flat filter with the slower speed may be set longer.

  In the artificial wetland for improving water quality according to the present invention, a plurality of artificial tidal flat filter beds are arranged in a stepped manner to form a staircase constructed wetland group, and the raw water supply unit for the staircase constructed wetland group is the staircase constructed wetland group. Placed on the uppermost artificial tidal filter bed, two pairs of artificial tidal flats adjacent to each other in a staircase constructed wetland group, and a filter medium breathing mechanism for each set. The drainage part of the filter medium breathing mechanism, which has a water absorption part on the artificial tidal flat filter bed, is placed above the artificial tidal flat filter bed one stage lower than the upper stage to serve as the water supply section for the artificial tidal filter bed one stage lower. In addition, it is preferable to provide a treatment port for draining the final treated water for the staircase constructed wetland group in the bottom artificial tidal flat filter bed of the staircase constructed wetland group.

  In the constructed wetland for water quality improvement according to the present invention, a plurality of artificial tidal flats are stacked to form a multistory constructed wetland group, and the water supply section of the multistory constructed wetland group is the uppermost artificial tidal flat filter bed The two-stage artificial tidal flat filter bed adjacent to the multi-layer constructed wetland group is set as one set, and the filter medium breathing mechanism is arranged for each set, and the water absorption part is placed on the upper artificial tidal flat filter bed of each set. The drainage part of the arranged filter medium breathing mechanism is located above the artificial tidal flat filter bed on the first stage lower side with respect to the upper stage side to serve as the water supply part for the artificial tidal flat filter bed on the first stage lower stage. It is preferable to arrange the treatment port for draining the treated water on the bottom artificial tidal flat filter bed of the multilayer constructed wetland group.

  In the artificial wetland for improving water quality according to the present invention, it is preferable that the raw water supply section for the multistory artificial wetland group is a water supply pipe extending from the raw water reservoir through a water supply pump.

  In the artificial wetland for improving water quality according to the present invention, it is preferable that the water absorption portion is provided with a filter mechanism that suppresses suction of the filter medium.

The artificial wetland for improving water quality according to the present invention includes a filter medium respiration mechanism for changing the water level in the artificial tidal flat filter at a predetermined respiration period cycle. The filter medium breathing mechanism has been used for decomposition during the period of rising water level, in which fresh air is sucked into the filter medium from the atmosphere side during the period of falling water level to drain the treated water from the filter medium, and the water to be treated penetrates into the filter medium. Exhale air from the filter medium to the atmosphere.
The filter medium breathing mechanism is a siphon tube mechanism. The siphon pipe mechanism is an inverted U-shaped pipe, and the water level in the water absorbed from the water absorption part at one end rises, and the water level is at the highest point of the inverted U-shaped pipe while expelling air from the pipe. When a certain operation reference water level is reached, drainage is performed due to the difference in water level between the water absorption level and the drainage water level, and the water level drops. By applying the siphon tube mechanism to the drainage of the filter medium, the water level of the filter medium can be easily changed.
The respiration period cycle can be adjusted by setting three conditions: the filter medium volume of the filter medium of the artificial tidal flat, the water penetration rate in the filter medium, and the operation reference water level of the siphon tube mechanism. The larger the is, the slower the permeation rate, and the higher the operation reference water level, the longer the breathing period cycle can be set. In this way, the water level of the filter medium can be changed, so by setting the water level fluctuation cycle according to the purpose, efficient reduction of BOD and nitrogen components using tidal flat tidal models in constructed wetlands Is possible.

In the artificial wetland for improving water quality according to the present invention , the filter medium breathing mechanism is a conduit check opening mechanism. The pipe non-return mechanism cuts off the pipe connecting the water absorption part and the drainage part until the water level of the water to be treated that has permeated the filter medium reaches the predetermined operational reference water level, When it reaches, the water level opening type check valve for opening the pipe connecting the water absorption part and the drainage part is provided. If air remains in the pipeline, the siphon tube mechanism does not operate normally. However, according to the above method, the check valve is opened when the water level reaches the operation reference water level. For example, even if the rise in the water level of the filter bed is gradual, it is possible to perform the same operation as the siphon tube mechanism.

In the artificial wetland for improving water quality according to the present invention, in order to set the respiration period cycle of two artificial tidal flat filter beds having the same infiltration rate and different filter medium volumes, the artificial tidal flat filter bed having a smaller filter medium volume is used. than the operating reference level, you set high operating reference level of the artificial tidal filter bed towards the filter medium has a large volume. Thereby, even if a filter medium volume differs, the water level fluctuation | variation period of a filter medium can be set according to the objective.

In the artificial wetland for improving water quality according to the present invention, with respect to the two artificial tidal flat filter beds having different infiltration rates with the same operation reference water level, the infiltration rate is higher than the breathing period cycle of the artificial tidal flat filter bed having a higher infiltration rate. The respiration period cycle of the artificial tidal flat filter with the slower speed can be set longer. Thereby, the filter medium of the osmosis | permeation rate suitable for a desired respiration period period can be selected.

  In the artificial wetland for improving water quality according to the present invention, a plurality of artificial tidal flats are arranged stepwise to form a staircase artificial wetland group, and one set of two-stage artificial tidal flat filter beds adjacent to the staircase artificial wetland group is provided. As described above, a filter medium breathing mechanism is arranged for each set. Thereby, for example, an artificial wetland group having a multi-stage configuration can be formed on an inclined land. Moreover, the water level of a filter medium can be changed in the constructed wetland group of a multistage structure, and the water level fluctuation | variation period can be set according to the objective. By using a multi-stage constructed wetland group, purification capacity can be improved. Moreover, it becomes possible to cope with different processing times required for reducing BOD and nitrogen components depending on purposes.

  In the artificial wetland for improving water quality according to the present invention, a plurality of artificial tidal flats are stacked to form a multistory artificial wetland group, and two sets of artificial tidal flats adjacent to the multistory artificial wetland group are set as one set, and each set is set. Place the filter media breathing mechanism. Thereby, the constructed wetland group of a multistage structure can be formed under a small installation area. Moreover, the water level of a filter medium can be changed in the constructed wetland group of a multistage structure, and the water level fluctuation | variation period can be set according to the objective. By using a multi-stage constructed wetland group, purification capacity can be improved. Moreover, it becomes possible to cope with the processing time required for reducing the BOD and nitrogen component which differ depending on the purpose.

  In the constructed wetland for improving water quality according to the present invention, the raw water supply unit for the multistory constructed wetland group is a water supply pipe that extends from the raw water storage tank through a water supply pump. By appropriately setting the capacity of the water supply pump, the number of layers can be increased, and an artificial wetland for efficient water quality improvement can be obtained with a smaller installation area.

  In the artificial wetland for improving water quality according to the present invention, the water absorption part is provided with a filter mechanism that suppresses suction of the filter medium, so that the filter medium breathing mechanism can be prevented from being clogged.

It is sectional drawing about the artificial tidal flat filter bed of the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a figure which shows the time fluctuation | variation of the water level at the time of using a filter medium with a coarse particle size about the artificial tidal flat filter bed of the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a figure which shows the time fluctuation | variation of the water level at the time of using the filter medium with a fine particle size about the artificial tidal flat filter bed of the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a figure which takes time on the horizontal axis and shows the water level on the vertical axis for the temporal fluctuation of the filter medium water level. 4A shows the fluctuation of the filter medium water level in FIG. 2, and FIG. 4B shows the fluctuation of the filter medium water level in FIG. It is a block diagram of a staircase-shaped artificial wetland group as the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a figure which shows the example which applies the structure of FIG. 5 as a terraced rice field structure in a slope. It is a block diagram of a multistory constructed wetland group as the constructed wetland for improving water quality in the embodiment according to the present invention. It is a figure which shows the result of having compared each operation effect about the multistory constructed wetland group of the structure of FIG. 7, and the conventional multistory constructed wetland group which does not use a siphon pipe mechanism. It is a figure which shows the water absorption part filter used for the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a figure which shows the subject when the siphon pipe mechanism is provided in the artificial wetland for water quality improvement in embodiment which concerns on this invention. It is a block diagram of the pipe line reverse opening mechanism as another filter-medium respiration mechanism. It is a figure which shows solution to the problem in FIG. 10 by using a pipe line check opening mechanism.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. The dimensions, shapes, types of filter media, the number of filter bed stages, and the like described below are examples for explanation, and can be appropriately changed according to the specifications of the constructed wetland. In the following, corresponding elements in all drawings are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of an artificial wetland 10 for improving water quality. Hereinafter, unless otherwise specified, the artificial wetland 10 for improving water quality is referred to as an artificial wetland 10. In FIG. 1, although not a constituent element of the constructed wetland 10, the treatment target water 4 to be improved in water quality and the treated water 6 after the water quality improvement are illustrated. The artificial wetland 10 is a water quality improvement treatment facility that drains the treated water 6 with reduced BOD and nitrogen components by utilizing the decomposition action of microorganisms on organic substances and nutrients contained in the water 4 to be treated. The BOD processed here includes organic BOD and nitrogenous BOD. Organic BOD may be referred to as carbonized BOD, and nitrogenous BOD may be referred to as N-BOD.

  The artificial wetland 10 includes an artificial tidal flat filter bed 20, a siphon pipe mechanism 40, and a water supply unit 48 that supplies the processing target water 4. The artificial tidal flat filter bed 20 includes a waterproof frame 22 and a filter medium 30 accommodated therein. The siphon tube mechanism 40 has a water absorption portion 50 that is a tip opening portion inserted into the filter medium 30, and a drainage portion 60 that opens to the outside of the waterproof frame body 22. The water 4 to be treated is supplied to the filter medium 30 of the artificial tidal flat filter 20 by the water supply unit 48. The treated water that has permeated the filter medium 30 and has been decomposed is absorbed from the water absorption part 50 of the siphon pipe mechanism 40, and the treated water 6 is discharged from the drain part 60 of the siphon pipe mechanism 40 to the outside. The vertical direction shown in FIG. 1 is a direction in which water falls along the direction of gravity. The height described below and the water level of the filter medium are values measured along this vertical direction.

The waterproof frame 22 is a container-like structure that forms the outer shape of the artificial tidal flat filter bed 20, separates the filter medium 30 from the outside, and partitions the processing target water 4 included in the filter medium 30 so as not to flow out. is there. As for the waterproof frame 22, the surrounding wall part 24 and the bottom face part 26 are waterproof structures, and the upper surface part 28 is open | released by the atmosphere side. The position where the filter medium 30 is in contact with the bottom surface portion 26 is a reference position O, and the height H ₀ of the peripheral wall portion 24 from the reference position O is higher than the top surface of the filter medium thickness D from the reference position O.

  As shown in FIG. 1, the water supply unit 48 that supplies the processing target water 4 to the filter medium 30 is provided on the upper surface side of the waterproof frame 22. Thus, when the treatment target water 4 is discharged from the water supply unit 48, it is poured into the filter bed 30 as it is by gravity. The treatment target water 4 can also be supplied from the bottom of the waterproof frame 22. In that case, the water supply part 48 is provided in the bottom part of the waterproof frame 22, and the process target water 4 is supplied to the filter bed 30 toward a vertical direction by water supply pressure. This method is close to a model that springs from the bottom in a natural tidal flat. The water 4 to be treated may be supplied from the peripheral wall portion 24 of the waterproof frame 22.

  The waterproof structure may not be a complete liquid shielding structure, and may have a slight leakage flow rate compared to the flow rate of the treated water 6 flowing through the siphon tube mechanism 40. Compared to the unit time, the leakage flow rate from the waterproof structure may be several percent or less of the flow rate of the treated water 6 flowing through the siphon tube mechanism 40. The waterproof structure can be composed of concrete, mortar, plastic material, or the like. Instead, the waterproof structure may be composed of a sheet material having low water permeability such as a plastic sheet. Moreover, the structure where the surrounding wall part and the bottom face part were comprised with the soil etc. with low water permeability, such as a clay, like the rice terrace mentioned later may be sufficient.

  The filter medium 30 is a filter material that is spread in the internal space of the waterproof frame 22 to form a biofilm or a plant rhizosphere microorganism group. The filter medium 30 is gravel, sand, soil, glass cullet, or the like. The filter medium volume V of the filter medium 30 accommodated in the waterproof frame 22 is represented by V = S × D using the filter medium thickness D and the filter medium area S in the waterproof frame 22.

  The biofilm is a microorganism film that adheres to the filter material of the filter medium 30. For example, a slimy layer is attached to gravel and sand in a river flow, and this layer is a film made of organic matter and nutrients contained in water and microorganisms that eat them. This membrane is a biofilm. Although not shown in FIG. 1, the plant rhizosphere microorganism group is a community of microorganisms in the filtering material around the roots of aquatic plants such as reeds that grow on the filter medium 30 and eats organic matter and nutrient salts.

  The microorganisms contained in the biofilm or the plant rhizosphere microorganism group include BOD oxidizing bacteria and N-BOD oxidizing bacteria. N-BOD oxidizing bacteria are called nitrifying bacteria. BOD-oxidizing bacteria take saccharides and organic acids into the body, and oxidatively decompose most of them by enzymatic reaction within about 48 hours. In addition, starch, protein, and lipid are reduced in molecular weight by hydrolysis and then oxidatively decomposed by enzymatic reaction. In this case, it takes time to lower the molecular weight. N-BOD oxidizing bacteria oxidize ammonia nitrogen in water to nitrate nitrogen, and the denitrifying bacteria reduce and decompose nitrate nitrogen in a subsequent denitrification step by nitrate respiration in an oxygen-free environment. By using BOD-oxidizing bacteria and N-BOD-oxidizing bacteria contained in biofilms and plant rhizosphere microorganisms, treated water that decomposes organic substances and nutrients contained in the water to be treated 4 and reduces BOD and nitrogen components 6

The siphon pipe mechanism 40 has a water absorption portion 50 that opens to the water absorption water level H ₁ measured from the reference position O at one end, and a drainage portion 60 that opens to a drain water level (−H ₂ ) on the lower water level side than the water absorption water level. At the other end. The siphon pipe mechanism 40 is an inverted U-shaped pipe line in which a part of the pipe line connecting the water absorption part 50 and the drainage part 60 is disposed at the operation reference water level H ₃ higher than the water absorption water level H ₁ .

The siphon pipe mechanism 40 does not drain the water contained in the filter medium 30 until the water level of the filter medium 30 reaches the operation reference water level H ₃ even if the water to be treated 4 is supplied from the water supply unit 48 to the artificial tidal flat filter bed 20. When the water level of the filter medium rises, the air in the pipe is expelled and reaches the operation reference water level H ₃ , the water level is drained to the outside as the treated water 6 from the drainage unit 60 for the first time to lower the water level of the artificial tidal flat filter bed 20. Therefore, the siphon tube mechanism 40 is a water level fluctuation mechanism that fluctuates the water level of the filter medium in the artificial tidal flat filter bed 20.

  When the water level fluctuation is divided into a water level drop and a water level rise, fresh air is sucked into the filter medium 30 from the atmosphere side during the period of the water level drop in which the treated water 6 is drained from the filter medium 30 of the artificial tidal flat filter bed 20. Further, when the water 4 to be treated is infiltrated into the filter medium 30 and reaches the reference position O, which is the bottom surface of the waterproof frame 22, the filter medium water level rises from there and is used due to the decomposition action of organic matter and nutrient salts. Exhaust air is exhaled from the filter medium 30 to the atmosphere side. Thus, the siphon tube mechanism 40 is a filter medium breathing mechanism that causes the filter medium 30 to perform an inhalation action for inhaling the atmosphere and an exhalation action for discharging the atmosphere.

  2 and 3 are diagrams showing the filter medium respiration action by the siphon tube mechanism 40. FIG. Here, the filter medium 30 is compared with a filter medium 32 having a coarse particle diameter and a filter medium 34 having a small particle diameter. As an example of the filter medium 32 having a coarse particle size, shale gravel having a particle size of about 5 mm to about 10 mm can be used. As an example of the filter medium 34 having a small particle size, shale gravel having a particle size of about 1 mm to 5 mm can be used. When glass cullet is used instead of shale gravel, glass cullet having a maximum particle size of about 10 mm can be used as the filter medium 32 having a large particle size. A glass cullet having a maximum particle size of about 1 mm to 5 mm can be used as the filter medium 34 having a small particle size.

  2 is a diagram in the case of using a filter medium 32 having a coarse particle diameter, and FIG. 3 is a diagram in the case of using a filter medium 34 having a small particle diameter. Each figure shows the artificial tidal flat filter bed 20, the filter medium 32 (or the filter medium 34), the treatment target water 4 and the treated water 6 in the constructed wetland 10 of FIG. 1, and shows the change of the water level in the artificial tidal flat filter bed 20 over time. It is sectional drawing. FIG. 4 is a transition diagram showing the time change with time on the horizontal axis and the filter medium water level which is the water level in the filter medium 32 (or filter medium 34) on the vertical axis. Hereinafter, the filter medium water level refers to the water level from the reference position O when the water to be treated 4 penetrates the entire filter medium 30 and then reaches the bottom surface of the waterproof frame 22 and the water level rises therefrom, or the reference position O. It is a water level that descends when the water level that has risen from is drained. It is not the position of the tip of the water 4 to be treated during infiltration.

  FIG. 2A is a diagram showing an initial state of the artificial tidal flat filter bed 20 of the coarse filter medium 32. In this state, the treatment target water 4 has not been supplied to the artificial tidal flat filter bed 20 yet. (B) is a figure which shows the state of the time tb when the process target water 4 was supplied to the artificial tidal flat filter bed 20. Since the particle diameter of the filter medium 32 is coarse, the supplied water 4 to be treated does not stay on the upper surface of the filter medium 32 and immediately starts to penetrate into the filter medium 32. Since the water 4 to be treated is infiltrating near the upper surface of the filter medium 32, the filter medium water level and the siphon water level are zero.

  (C) is a figure which shows the state of the time tc after the time tb. The processing target water 4 is continuously supplied, and the supplied processing target water 4 is infiltrating the filter medium 32. At this time, since the tip of the permeated treatment target water 4 has not yet reached the bottom surface of the waterproof frame 22, the filter medium water level and the siphon water level are zero.

(D) is a figure which shows the state of the time td after the time tc. Here, the processing target water 4 is continuously supplied, and the supplied processing target water 4 penetrates into the inside of the filter medium 32, and its tip reaches the bottom surface of the waterproof frame 22, and the water level rises therefrom. In (d), the filter medium water level measured from the reference position O is indicated as H _U1 . The siphon water level is also H _U1 .

(E) is a figure which shows the state of the time te after the time td. Here, due to the waterproof action of the waterproof frame 22, the water level of the artificial tidal flat filter bed 20 rises from the bottom side, and the water 4 to be treated that has permeated the filter medium 30 diffuses and spreads inside the filter medium 32. The area remaining on the upper surface portion side is reduced. In this way, the water to be treated 4 that has penetrated into the filter medium 32 by the action of the waterproof frame 22 diffuses and spreads inside the filter medium 32, thereby decomposing organic substances and nutrient salts in a wide range of the filter medium volume V of the filter medium 32. Water quality improvement efficiency is improved. Before and after this state is reached, water supply of the water 4 to be treated is stopped. In (e), the filter medium water level measured from the reference position O is indicated as H _U2 . The siphon water level is also H _U2 .

  In (b) to (e) of FIG. 2, the water 4 to be treated penetrates into the filter medium 32. Since the filter medium 32 contains microorganisms that decompose, organic substances and nutrients contained in the permeated water 4 to be treated are decomposed by the decomposition action of the microorganisms. The microorganisms consume oxygen in the air contained in the filter medium 32 and perform a decomposition action. The air in the filter medium 32 in which oxygen is reduced by the decomposition action is replaced with the permeation of the water 4 to be treated into the filter medium 32, and is discharged to the atmosphere as used air 3 from the portion exposed to the atmosphere on the upper surface of the filter medium 32. The This is the exhalation action of the filter medium 32. Since the exhalation action occurs during the period of the water level rise in the filter medium 32, it continues until the time tf described below.

(F) is a figure which shows the state of the time tf after the time te. At time tf, the filter medium water level further rises above H _U2 , and both the filter medium water level and the siphon water level reach the operation reference water level H ₃ while air is expelled from the inverted U-shaped pipe line of the siphon pipe mechanism 40. At this time, according to the principle of siphon, the water in the filter medium 32 is drained as treated water 6 from the drainage part 60 through the siphon tube mechanism 40. Thereby, a filter medium water level falls.

(G) the time elapses from the time tf, the filter medium water level is a diagram showing a state of operating reference level H ₃ time becomes H _D from tg. H _D is higher than the water absorption level H ₁ . Therefore, drainage by the siphon tube mechanism 40 is continuing, and the treated water 6 is drained from the drainage part 60. Although the filter medium water level continues to decrease, the siphon water level maintains the operation reference water level H ₃ until the water of the filter medium 32 is not drained.

  In (g) of FIG. 2, the water in the filter medium 30 is drained as the treated water 6 through the siphon tube mechanism 40, so that it is replaced with the drained treated water 6 and fresh from the air exposed surface on the upper surface of the filter medium 32. Fresh air 2 is supplied to the filter medium 32. This is the intake action of the filter medium 32. Since the intake action occurs during the period when the water level of the filter medium 32 falls, it continues until the time th described below.

(H), the time elapses from the time tg, the water level of the filter medium 32 is a diagram showing a state where a water level H ₁ decreases. Since no water filter medium 32 is drained more, also treated wastewater 6 is entirely from the siphon tube mechanism 40, siphon the water level also becomes water level H _1.

  The above is the explanation of the fluctuation of the water level and the filter medium breathing action when the filter medium 32 having a coarse particle diameter is used. FIG. 3 is a diagram showing the fluctuation of the water level and the filter medium respiration effect when the filter medium 34 having a small particle diameter is used. In FIG. 2, because the particle size of the filter medium 32 is coarse, the water 4 to be treated from the water supply unit 48 does not stay on the upper surface of the filter medium 30 and immediately permeates the filter medium 32. That is, (permeation flow rate per unit time in the filter medium 32)> (feed water flow rate per unit time from the water supply unit 48). In FIG. 3, it is assumed that the filter medium 34 having a fine particle diameter satisfying (the permeation flow rate per unit time in the filter medium 34) <(the feed water flow rate per unit time from the water supply unit 48) is used. When this filter medium 34 is used, the water 4 to be treated from the water supply unit 48 cannot completely penetrate into the filter medium 34 simultaneously with the water supply, and a part of the water stays on the upper surface of the filter medium 34.

  3A to 3H correspond to FIGS. 2A to 2H, respectively. Compared with FIG. 2, the water 4 to be treated remains on the upper surface of the filter medium 34 in FIGS. 3 (b) to 3 (d). As shown in FIG. 3 (e), the staying water 4 to be treated gradually permeates the filter medium 34. Then, the area left as it is is finally eliminated. The difference between FIG. 2 and FIG. 3 is due to (the permeation flow rate per unit time in the filter medium 32)> (the permeation flow rate per unit time for the filter medium 34). In other words, the time for the treatment target water 4 to permeate the filter medium thickness D is longer for the filter medium 34 in FIG. 3 than for the filter medium 32 in FIG. Excluding this difference, the contents of FIGS. 3A to 3H are the same as the contents of FIGS. 2A to 2H, respectively, and thus detailed description thereof is omitted.

  FIG. 4 is a diagram showing time-series changes with time on the horizontal axis and the filter medium water level on the vertical axis. 4A is a diagram for the case of FIG. 2 using a filter medium 32 having a coarse particle diameter, and FIG. 4B is a diagram for the case of FIG. 3 using a filter medium 34 having a small particle diameter. In each figure, ta to th are the times described in FIG. 2 and FIG.

4A, the filter medium water level is zero = reference position O until time tb. After time tb, the filter medium water level = 0 even at time tc. The filter medium water level starts to rise from the time before time td. In FIG. 4A, it is assumed that the filter medium water level = the water absorption water level H ₁ near the time td. As the time elapses, the filter medium water level gradually increases, and at time tf, the filter medium water level = the operation reference water level H ₃ . As tb = ta when time tb is immediately after the time ta, a period T ₁ of the from the time ta to time tf is a period during which the filter medium water level is rising, expiratory period filter media 32 is performing the breath It is. From time tf, the filter medium water level starts to decrease, and at time th, the filter medium water level = water absorption level H ₁ . A period T ₂ from time tf to time th is an intake period in which the filter medium 32 is performing intake.

Thus, the filter medium 32 performs an exhalation action in the period T ₁ during which the filter medium water level rises, and performs an intake action during the period T ₂ during which the filter medium water level falls. The period from time ta to time th is (T ₁ + T ₂ ), which corresponds to one breathing period of the filter medium 32.

During the period T ₁ in which the exhalation action is performed in one breathing period, air is expelled from the filter medium 32, so that the oxygen is insufficient in the filter medium 32. Therefore, it becomes an environment suitable for denitrifying bacteria that perform a decomposing action by a reducing action without using oxygen. On the other hand, in the period T ₂ during which the intake action is performed, air is sent to the filter medium 32, so that the filter medium 32 has a sufficient amount of fresh oxygen. Therefore, it becomes an environment suitable for BOD oxidation bacteria which decomposes using oxygen. Depending on the composition of the water 4 to be treated, the water quality can be effectively improved by appropriately allocating and balancing the period T ₁ for performing the exhalation action and the period T ₂ for performing the inhalation action.

In an example such as a student cafeteria where the water 4 to be treated is generated once a day in the day, it is sufficient to use the artificial wetland 10 for one breathing period a day. On the other hand, in the example of domestic sewage in which the treatment target water 4 is generated throughout the day, it is necessary to continuously repeat the breathing period in addition to one breathing period per day. For this purpose, the water to be treated 4 is supplied again from the water supply unit 48 in the state of time th in FIG. The state at time th in FIG. 2 (h) is substantially the same as the initial state in FIG. 2 (a). The difference is that the filter medium water level = the reference position O in FIG. 2 (a), but the filter medium water level = water absorption level = H ₁ at time th in FIG. 2 (h). Therefore, the water level of the filter medium is increased by re-supplying the water to be treated 4 from the water supply unit 48 at time th, and thereafter, the states described in FIGS. 2B to 2H are repeated.

If this is demonstrated in Fig.4 (a), the filter medium 32 of the artificial tidal flat filter bed 20 can repeat inhalation | exhalation and expiration by re-supplying the process target water 4 in time th or the time before and after that. . In FIG. 4 (a), the water level fluctuation in one breathing period corresponding to (a) to (h) in FIG. 2 is indicated by a thick solid line, and the water level fluctuation in each subsequent breathing period is indicated by a thin solid line. If necessary, the water may be re-supplied after an appropriate margin time without being re-supplied immediately at the time th. When inhalation and expiration are repeated, a breathing period period T ₀ which is a repetition period of expiration and inspiration is T ₀ = (T ₁ + T ₂ ).

  4 (b) showing the fluctuation of the filter medium water level in the case of FIG. 3 using the filter medium 34 having a fine particle diameter corresponds to the time axis of FIG. 4 (a) extended for the filter medium 32 having a coarse particle diameter. . This is due to the relationship of (permeation flow rate per unit time in the filter medium 32)> (permeation flow rate per unit time for the filter medium 34). In the example of FIG. 4, one breathing period of the filter medium 34 is about twice as long as one breathing period of the filter medium 32. This is an illustrative example, and the ratio is different depending on the specifications of the filter media 32 and 34.

The respiration period period T ₀ = (T ₁ + T ₂ ), which is a repetition period of exhalation and inspiration, is the volume V of the filter medium 30 of the artificial tidal flat filter 20, the water permeation rate in the filter medium 30, and the siphon tube mechanism 40. It can be adjusted by setting the operating reference level H _3. Assuming other conditions are the same, the breathing period period T ₀ = () as the filter medium volume V of the filter medium 30 of the artificial tidal flat filter bed 20 increases, the water permeation rate through the filter medium 30 decreases, and the operation reference water level H ₃ increases. T ₁ + T ₂ ) becomes longer. These conditions may be set according to the purpose of water quality improvement in the constructed wetland 10.

As Example 1, in the case of a large-scale constructed wetland 10 in which the filter medium volume V of the filter medium 30 inside the artificial tidal flat filter bed 20 is large and the specification is to reduce the organic matter BOD of the water 4 to be treated in a short time, The breathing period period T ₀ is shortened. On the other hand, as the case 2, in the same large-scale constructed wetland 10, when it is desired to reduce the N-BOD of the treatment target water 4 over time, the respiration period cycle T ₀ in the case 2 is lengthened. In Case 1 and Case 2, the filter media volume V of the filter medium 30 are the same, than the operating reference level H ₃ of the siphon tube mechanism 40 in case 1, the operating reference level H ₃ of the siphon tube mechanism 40 in Case 2 To be higher. This allows longer than the breathing period period T ₀ the respiratory period period T ₀ in the case 2 in Example 1.

With the operation reference water level H ₃ of the siphon tube mechanism 40 kept the same, the filter medium 32 having a coarse particle diameter may be used in the case 1, and the filter medium 34 having a small particle diameter may be used in the case 2. In this case, the water penetration speed of the filter medium 32 in the artificial tidal flat filter bed 20 of Example 1 is high, and the water penetration speed of the filter medium 34 in the artificial tidal flat filter bed 20 of Case 2 is low. Therefore, it can be made longer than the breathing period period T ₀ the respiratory period period T ₀ in the case 2 in Example 1.

Filter medium volume V1 of filter medium 30 of case 1 = (filter medium area S1 × filter medium thickness D1), filter medium volume V3 of filter medium 30 of case 3 = (filter medium area S1 × filter medium thickness D3), filter medium thickness D3> filter medium In the case of the thickness D1, suppose that it is desired to reduce the organic matter BOD of the water to be treated 4 in the same time. In this case, it suffices to respiratory period period T ₀ of the respiratory period cycle T ₀ and case 3 of Example 1 in the same. Since (filter medium volume V3 of filter medium 30 of case 3)> (filter medium volume V1 of filter medium 30 of case 1), the siphon pipe in case 3 is higher than the operation reference water level H ₃ of the siphon pipe mechanism 40 in case 1. The operation reference water level H ₃ of the mechanism 40 is increased. As another method, the filter medium 32 having a coarse particle diameter may be used in the case 1, and the filter medium 34 having a small particle diameter may be used in the case 3.

As example 4, the treatment target water 4 containing a large amount of organic matter BOD was brought into one artificial tidal flat filter bed 20 on one day, and the treatment target water 4 containing a large amount of N-BOD was carried on another day. To do. In this case, the operation standard of the siphon pipe mechanism 40 is set so that the period T ₂ during which the intake action is performed is matched with the time required for decomposing the organic substance BOD on the day when the treatment target water 4 containing a large amount of the organic substance BOD is carried. to set the water level H _3. In addition, on the day when the water 4 to be treated containing a large amount of N-BOD is brought in, the operation reference water level of the siphon pipe mechanism 40 is adjusted so that the time T ₁ during which exhalation is performed is matched with the time required to decompose the N-BOD. setting the H _3.

In this way, by setting the operation reference water level H ₃ of the siphon tube mechanism 40 according to the filter medium volume V, the filter medium area S, and the filter medium thickness D of the filter medium 30 of the artificial tidal flat filter bed 20, the water level fluctuation of the filter medium 30 is set. Can be set according to the purpose of the artificial tidal flat filter bed 20. Alternatively, depending on the processing content of the target water 4 was brought, by performing the setting of the operating reference level H ₃ of the siphon tube mechanism 40 can set the cycle of the level change of the filter medium 30. In addition, when there are many types of artificial tidal flat filter beds 20 having filter media 32 and 34 having different particle sizes, the artificial tidal flat filter bed 20 having filter media 32 and 34 having a particle size suitable for the contents of the water 4 to be treated is selected. May be.

  The filter medium area S required for the constructed wetland 10 may be secured by one artificial tidal flat filter bed 20, but the necessary filter medium area S may be secured by an artificial wetland group including a plurality of artificial tidal flat filter beds 20. For example, a plurality of artificial tidal flat filter beds 20 are connected in series between adjacent artificial tidal flat filter beds 20 using a siphon tube mechanism 40, so that the artificial wetland group has one water supply unit that supplies raw water, and the final treatment. Only one processing port for draining water is required, and the configuration is simplified.

  The step-like constructed wetland group 12 shown in FIG. 5 is an example in which six artificial tidal flat filter beds 20a, 20b, 20c, 20d, 20e, and 20f are connected in series using the step-like structure 11 or topography. It is. The number of artificial tidal flat filter beds 20 may be other than six.

  Each of the artificial tidal flat filter beds 20a, 20b, 20c, 20d, 20e, and 20f accommodates filter media 30a, 30b, 30c, 30d, 30e, and 30f. The uppermost artificial tidal flat filter 20a is provided with a water supply unit 48 for supplying raw water, which is the processing target water 4 for the stepped artificial wetland group 12. Further, the lowermost artificial tidal flat filter bed 20f is provided with a treatment port portion 62 for draining the final treated water 8 for the stepped constructed wetland group 12.

  Two steps of artificial tidal flat filter beds adjacent to each other in the staircase constructed wetland group 12 are connected by siphon tube mechanisms 40a, 40b, 40c, 40d, and 40e, respectively. The connection relationship is the same for each set of two sets of artificial tidal flats adjacent to each other. For example, the uppermost artificial tideland filter bed 20a and the next lower artificial tideland filter bed 20b will be described. The upper artificial tideland filter bed 20a has a water absorption part 50a of the siphon pipe mechanism 40a. Be placed. The drainage section 60a of the siphon pipe mechanism 40a is disposed above the lower artificial tideland filter bed 20b, and the first treated water 6a treated by the upper artificial tideland filter bed 20a is used as the lower artificial tideland filter bed. It becomes the water supply part 48b which supplies water to 20b.

  The same applies to the two adjacent artificial tideland filter beds 20b and 20c. The drainage part 60b of the siphon pipe mechanism 40b having the water absorption part 50b on the artificial tideland filter bed 20b on the upper side is the artificial tideland filter bed on the lower side. It is arranged above 20c. This drainage part 60b becomes the water supply part 48c which supplies the 2nd treated water 6b processed with the artificial tidal flat filter bed 20b to the artificial tidal flat filter bed 20c of the lower stage side. The same applies to the other siphon tube mechanisms 40c, 40d, and 40e. In this way, the six artificial tidal filter beds 20a, 20b, 20c, 20d, 20e, and 20f are connected in series by the five siphon tube mechanisms 40a, 40b, 40c, 40d, and 40e.

In the configuration of FIG. 5, when the processing target water 4 that is the raw water is supplied from the water supply unit 48 in the uppermost artificial tidal flat filter bed 20a, as shown in FIG. 2, the raw water is supplied until time tf. Although the water level rises, there is no drainage from the drainage part 60a. When the time becomes tf, the water level reaches the operation reference water level H ₃ of the siphon tube mechanism 40a, the first treated water 6a is drained from the drain portion 60a of the siphon tube mechanism 40a. The drained first treated water 6a is supplied to the filter medium 30b of the artificial tidal flat filter bed 20b on the lower stage side.

  The operation when the first treated water 6a is supplied to the second-stage artificial tidal filter bed 20b is the same as that of the first-stage artificial tidal filter bed 20b. When time tf is measured from when the first treated water 6a is supplied, the water level reaches the operation reference water level of the siphon tube mechanism 40b, and the second treated water in the artificial tidal flat filter bed 20b from the drainage part 60b of the siphon tube mechanism 40b. 6b is drained. The drained second treated water 6b is further supplied to the filter medium 30c of the artificial tidal flat filter bed 20c on the lower side.

  By repeating this, the fifth treated water 6e treated by the fifth-stage artificial tidal flat filter bed 20e becomes the filter medium 30f of the lowermost artificial tidal flat filter bed 20f using the drainage section 60e of the siphon pipe mechanism 40e as the water supply section 48f. Water is supplied. The filter medium 30f decomposes the organic matter and nutrients of the supplied fifth treated water 6e and drains it from the treatment port 62 as the final treated water 8 of the stepped constructed wetland group 12. Thus, in the step-like constructed wetland group 12, the raw water that is the treated water 4 that has been supplied is finally subjected to water quality improvement through the six-stage artificial tidal flats 20a, 20b, 20c, 20d, 20e, and 20f. It is recovered as treated water 8.

  The stepped artificial wetland group 13 in FIG. 6 is an example in which a plurality of artificial tidal flat filter beds 21a, 21b, and 21c have a terraced structure using a stepped landform. In the rice terrace configuration, a clay-like partition wall and a bottom wall are used as a waterproof structure.

  In the terraced rice pad configuration, a water supply section 48 for supplying raw water as the treatment target water 4 is provided on the uppermost artificial tidal flat filter bed 21a, and a processing port section 62 for draining the final treated water 8 to the lowermost artificial tidal flat filter bed 21c. Is provided. A siphon tube mechanism 41a is provided between adjacent artificial tidal filter beds 21a and 21b, and a siphon tube mechanism 41b is provided between adjacent artificial tidal filter beds 21b and 21c. Since the action of the stepped constructed wetland group 13 is the same as the action of the stepped constructed wetland group 12 of FIG. 5, detailed description thereof is omitted.

  In the above, one siphon tube mechanism was used for one artificial tidal flat, but when the planar shape is complicated and the area is large as in the terraced rice pad configuration of FIG. 6, one artificial tidal flat is necessary. Multiple siphon tube mechanisms may be used for the filter bed.

  The multistory constructed wetland group 14 shown in FIG. 7 has six artificial tidal flats 23a, 23b, 23c, 23d, 23e, and 23f stacked in a vertical direction on a flat structure 15 or terrain and adjacent to each other. The filter bed is connected in series. By adopting the multi-layer structure, the filter medium volume V can be increased while the installation area is substantially the same as the filter medium area S. The number of artificial tidal flats may be other than six.

  Similarly to the example of FIG. 5, the filter media 30a, 30b, 30c, 30d, 30e, and 30f are accommodated in the artificial tidal flats 23a, 23b, 23c, 23d, 23e, and 23f, respectively. In the multistory constructed wetland group 14, a water storage tank 16 that stores raw water that is the treatment target water 4 is disposed on the upper surface of the flat structure 15. A water supply pump 17 is connected to the water storage tank 16. The feed water pump 17 pumps the raw water as the treatment target water 4 from the water storage tank 16 and supplies the raw water to the raw water supply unit 48 provided above the uppermost artificial tidal flat filter bed 23 a via the water supply pipe 18. The lowermost artificial tideland filter bed 23 f is provided with a treatment port portion 62 for draining the final treated water 8 from the multilayer constructed wetland group 14.

  In the multilayer constructed wetland group 14, two adjacent artificial tidal flats are connected by siphon tube mechanisms 43a, 43b, 43c, 43d, and 43e, respectively. The connection relationship is the same for each set of two sets of artificial tidal flats adjacent to each other. For example, the uppermost artificial tideland filter bed 23a and the next lower artificial tideland filter bed 23b will be described. The upper artificial tideland filter bed 23a has a water absorption part 50a of the siphon pipe mechanism 43a. Be placed. The drainage part 60a of the siphon pipe mechanism 43a is arranged above the lower artificial tideland filter bed 23b, and the first treated water 6a treated by the upper artificial tideland filter bed 23a is used as the lower artificial tideland filter bed. It becomes the water supply part 48b which supplies water to 23b.

  The same applies to the two adjacent artificial tideland filter beds 23b and 23c. The drainage part 60b of the siphon pipe mechanism 43b having the water absorption part 50b on the upper artificial tideland filter bed 23b is connected to the lower artificial tideland filter bed. It is arrange | positioned above 23c. This drainage part 60b becomes the water supply part 48c which supplies the 2nd treated water 6b processed with the artificial tidal flat filter bed 23b to the artificial tidal flat filter bed 23c of the lower stage. The same applies to the other siphon tube mechanisms 43c, 43d, and 43e. In this way, the six artificial tidal filter beds 23a, 23b, 23c, 23d, 23e, and 23f are connected in series by the five siphon tube mechanisms 43a, 43b, 43c, 43d, and 43e.

  In addition, it is preferable that the adjacent siphon pipe mechanism avoids disposing the water absorption part of the lower artificial tideland filter bed directly below the water supply part from the upper artificial tideland filter bed. In the example of FIG. 7, the position of the water absorption part in the lower artificial tideland filter bed is shifted from the position of the water supply part from the upper artificial tideland filter bed along the width direction perpendicular to the vertical direction. By doing so, it is possible to improve the uniformity of the water distribution in the artificial tidal flat.

The operation of the configuration of FIG. 7 is the same as that of the stepped constructed wetland group 12 of FIG. That is, the raw water is supplied from the raw water supply section 48 in the uppermost artificial tidal flat filter 23a, as in the configuration of FIG. When it is time tf measured from when the raw water is water, the water level reaches the operation reference water level H ₃ of the siphon tube mechanism 43a, a first treated water 6a is drained from the drain portion 60a of the siphon tube mechanism 43a, one Water is supplied to the filter medium 30b of the artificial tidal flat filter bed 23b on the lower side.

  In the second-stage artificial tidal flat filter bed 23b, the first treated water 6a is supplied from the drainage part 60a = the water supply part 48b of the siphon pipe mechanism 43a. When time tf is measured from when the first treated water 6a is supplied, the water level reaches the operation reference water level of the siphon pipe mechanism 43b, and the second treated water in the artificial tidal flat filter bed 23b from the drainage part 60b of the siphon pipe mechanism 43b. 6b is drained. The drained second treated water 6b is supplied to the filter medium 30c of the artificial tideland filter bed 23c on the lower stage side.

  By repeating this, the fifth treated water 6e treated with the fifth-stage artificial tidal flat filter bed 23e becomes the filter medium 30f of the lowermost artificial tidal flat filter bed 23f using the drainage section 60e of the siphon pipe mechanism 43e as the water supply section 48f. Water is supplied. The filter medium 30f decomposes the organic matter and nutrient salts of the supplied fifth treated water 6e and drains it from the treatment port 62 as the final treated water 8 of the multilayer constructed wetland group 14. Thus, also in the multistory constructed wetland group 14, the same action as the step-like constructed wetland group 12 is performed, and the raw water as the treatment target water 4 is converted into the six-stage artificial tidal flat filter beds 23a, 23b, 23c, 23d, Through 23e and 23f, the final treated water 8 with improved water quality is recovered.

  In a configuration in which a plurality of artificial tidal flats are connected in series, such as the stepped constructed wetland group 12 in FIG. 5 and the multi-layer constructed wetland group 14 in FIG. 7, the filter medium and the lower stage constituting the upper artificial tidal flat filter bed are used. The filter medium constituting the artificial tidal flat on the side can be different. For example, a filter medium 32 having a coarse particle size is used as the filter medium constituting the upper artificial tideland filter bed, and a filter medium 34 having a small particle diameter is used as the filter medium constituting the lower artificial tideland filter bed.

  FIG. 8 summarizes the results of comparing the effects of the constructed constructed wetlands with the prior art. As the constructed wetland, a multistory constructed wetland group in which filter media having the same filter medium area S and filter medium thickness D were accommodated and five artificial tidal flats having the same inner shape and size were stacked was used. The filter medium constituting the filter bed uses a glass cullet having a maximum particle size of about 10 mm as the coarse filter medium 32 for the upper two stages and the maximum particle as the fine filter medium 34 for the lower three stages. A glass cullet having a diameter of about 5 mm was used. The conventional multi-layer constructed wetland group does not use a waterproof frame or siphon tube mechanism, and directly between the bottom of the artificial tidal flat on the upper stage and the upper surface of the artificial tidal flat on the lower stage between adjacent artificial tidal flats. Thus, water was dripped. In FIG. 8, the multi-layer constructed wetland group having five layers in the configuration of FIG. 7 is classified as “tidal flat type”, and the conventional multi-layer constructed wetland group is distinguished as “conventional type”.

FIG. 8 summarizes the results of obtaining the purification rate for the four evaluation indices when the accumulated water supply amount of the raw water that is the treatment target water 4 is sequentially increased. The total amount of raw water supply is 10L, 250L, 500L, 750L, and 1000L, assuming that 1L = 1000 cm ³ . The four evaluation indexes are BOD as biochemical oxygen demand, COD as chemical oxygen demand, n-Hex (normal hexane) as oil, and suspended solid mass SS (Suspended Solid). These indicated the detected value in mg / L.

  The purification rate (%) was determined by [1-{(detected value in final treated water) / (detected value in raw water)}] × 100. The significance test between the purification rate of the “tidal flat type” and the purification rate of the “conventional type” uses the p-value of the t test, and when p <0.05, “significantly different”, and p> 0. When “10”, “no significant difference” was set, and when 0.05 <p <0.10, “significant difference tendency” was set.

  From the results of FIG. 8, there is a significant difference between the biochemical oxygen demand BOD and the chemical oxygen demand COD in that the “tidal flat” purification rate is better than the “conventional” purification rate. On the other hand, regarding the purification rate of n-Hex as an oil component, a significant difference tendency is recognized between “tidal flat type” and “conventional type”, and the purification rate of suspended solid mass SS is “tidal flat type” and “ There is no significant difference from the conventional type. The reason why no significant difference is observed in the SS purification rate is that the selection of the particle size of the filter medium 30 may be insufficient.

  Although not clearly shown in FIG. 8, when the cumulative amount of raw water is gradually increased, the treatment time tends to increase even in the “tidal flat type”. This is considered that clogging in the water absorption part of the siphon tube mechanism is starting to occur. As a countermeasure against this, as shown in FIG. 9, a filter 70 is provided for the water absorption portion of the siphon tube mechanism 40. The filter 70 contains a filter material having a particle size larger than the inner diameter of the pipe line of the siphon tube mechanism and having a particle size several times larger than the particle size of the filter medium 30 in a reed with a mesh outer periphery. . As the material of the filter material, shale, glass cullet and the like can be used. By the action of the mesh of the ridges and the particle size of the filter material, the filter medium 30 is suppressed from entering the inner diameter of the pipe line of the siphon pipe mechanism 40, and clogging in the water absorption part of the siphon pipe mechanism 40 can be suppressed.

The siphon pipe mechanism 40 is an inverted U-shaped pipe line having a water supply part 50 at one end and a drainage part 60 at the other end. The water level in the pipe line of water absorbed from the water absorption part 50 at one end rises, and when the water level reaches the operation reference water level H ₃ which is the highest point of the inverted U-shaped pipe line while expelling air from the pipe line, the water absorption level H Drainage is performed by the difference in water level between ₁ and the drainage water level (−H ₂ ), and the water level falls. By applying the siphon tube mechanism 40 to the drainage of the filter medium 30, the filter medium water level can be easily changed. If, in the siphon tube mechanism 40, the water level rising speed is a gradual, even if the water level becomes near the reference operation level H _3, when still have air conduit, not work principle of siphon. At this time, the siphon water level and the filter medium water level remain in the vicinity of the operation reference water level H ₃ , and the filter medium water level cannot be changed. An example in which the water level rising speed is slow is when the water permeation speed in the filter medium 30 is small, as described in FIGS. Further, when the filter medium volume V is large with respect to the amount of water supply, the water level rising speed becomes slow.

FIG. 10 is a diagram illustrating an example in which the filter medium water level remains in the vicinity of the operation reference water level H ₃ when the water level rising speed in the filter medium 30 is moderate. FIG. 10A shows the case where the filter medium water level H ₂₉ has not yet reached the maximum height of the inverted U-shaped pipe line of the siphon pipe mechanism 40. (B) is a state immediately before the filter medium water level H ₂₉ of (a) slowly rises to the filter medium water level H ₃₀ . Medium water level H _30, in an inverted U-shaped conduit up to the height of the siphon tube mechanism 40, is a lower height level height of the tube, siphon tube mechanism 40 when the water level rising rate is suitably faster It corresponds to the operation reference water level H ₃ that operates. In FIGS. 10A and 10B, drainage from the siphon tube mechanism 40 is not yet performed.

FIG. 10C shows the state when the filter medium water level slowly rises from the state (b) and reaches the filter medium water level H ₃₁ exceeding the filter medium water level H ₃₀ . At this time, since the filter medium water level rises slowly, air remains in the maximum height portion of the inverted U-shaped pipe line of the siphon pipe mechanism 40 without being expelled. Accordingly, the treated water 6 exceeding the filter medium water level H ₃₀ is dripped little by little along the inner wall of the siphon tube mechanism 40 as dripping water 7. Thereby, even if the filter medium water level rises, the corresponding dropped water 7 is drained. Therefore, the filter medium water level is lowered, and when the filter medium water level H _{30 is} lowered, the drainage of the dropped water 7 stops.

FIG. 10 (d) once after down to medium water level H _30, beyond the filter medium water level H ₃₀ and filter medium water level rises again by the feed water or the like, and when it becomes medium water level H _31. Also at this time, as in the case of FIG. 10C, the filter medium water level slowly rises, so that air is not yet expelled to the maximum height portion of the inverted U-shaped pipe line of the siphon pipe mechanism 40. Remain. Accordingly, the treated water 6 exceeding the filter medium water level H ₃₀ is dripped little by little along the inner wall of the siphon tube mechanism 40 as dripping water 7. Thereby, even if the filter medium water level rises again to H ₃₁ , the dropped water 7 is drained accordingly, so that the filter medium water level decreases, and when the filter medium water level falls to H ₃₀ , the drainage of the dropped water 7 stops. Since repeating this, the filter medium water level remains caught H ₃₀ near does not work principle of siphon.

FIG. 11 is a configuration diagram of a pipe non-return opening mechanism 100 as a filter medium breathing mechanism capable of changing the filter medium water level even when the filter medium water level slowly rises. Conduit check opening mechanism 100, until the filter medium water level reaches the operation reference water level H ₃ is, closes the passage portion connecting the water absorbing portion drainage unit, the water absorption unit when the filter medium water level reaches the operation reference water level H ₃ Open the pipe line connecting the drainage part.

  The pipe non-return opening mechanism 100 is a mechanism that is connected to the artificial tidal flat filter bed 20 that houses the filter medium 30 therein. The intermediate water tank 102, a support base 120 that supports the intermediate water tank 102, and a lower part of the support base 120. A drainage stand 122 is provided.

  The intermediate water tank 102 is a water tank that temporarily stores the treated water 6 having a water level corresponding to the filter medium water level of the artificial tidal flat filter bed 20. The inner volume of the intermediate water tank 102 is smaller than the inner volume defined by the waterproof frame 22 of the artificial tidal flat filter bed 20. For example, the inner volume of the intermediate water tank 102 is 1% or less of the inner volume defined by the waterproof frame 22 of the artificial tidal flat filter bed 20. Preferably it is good to set it as about 0.1%-1%.

The communication pipe 104 is a pipe line having a water absorption part 54 provided at the bottom surface of the artificial tidal flat filter bed 20 at one end and a water supply part 49 provided at the bottom face of the intermediate water tank 102 at the other end. The position of the bottom surface of the intermediate water tank 102 is (−H ₄ ) below the reference position O. Thus, since the water absorption part 54 is provided at a position higher than the water supply part 49 by + H ₄ , when the treated water 6 is contained in the artificial tidal flat filter bed 20, the intermediate water tank 102 is provided with an artificial tidal flat filter by the communication pipe 104. The treated water 6 is accommodated at the same water level as the filter medium water level of the floor 20.

The water level pipe 106 erected in the vertical direction in the intermediate water tank 102 has an upper opening 56 at the height of the operation reference water level H ₃ of the artificial tidal flat filter bed 20, and the lower opening 58 is inside the drainage stand 122. It is a pipe line provided toward. When the filter medium water level of the artificial tidal flat filter bed 20 rises slowly and exceeds the operation reference water level H ₃ , the water level pipe 106 introduces the excess treated water 6 into the upper opening 56 and travels along the inner wall of the pipe line. The dripping water 7 is dropped from the lower opening 58 toward the inside of the drainage stand 122.

  The check pipe 108 erected vertically in the intermediate water tank 102 is a pipe line having an upper valve seat 110 that opens in a funnel shape at one end and a lower opening 64 at the other end. The upper valve seat 110 is disposed in the inner space of the intermediate water tank 102, and the lower opening 64 opens toward the inside of the drainage stand 122.

  The check valve body 112 has a spherical outer shape, and is received by a conical slope opening in a funnel shape of the upper valve seat 110 in the check tube 108 by its own weight. The upper valve seat 110 of the check tube 108 and the check valve body 112 constitute a check valve. When the spherical outer shape of the check valve body 112 is received by and contacted with the funnel-shaped conical slope of the upper valve seat 110, the conduit of the check pipe 108 is blocked. In the shut-off state, even if the inner space of the intermediate water tank 102 is filled with the treated water 6, the treated water 6 does not flow into the inner space of the drainage table 122 due to the action of the check valve. When the spherical outer shape of the check valve body 112 is separated from the funnel-shaped conical slope of the upper valve seat 110, the conduit of the check tube 108 is opened. When the inner space of the intermediate water tank 102 is filled with the treated water 6 in the open state, the treated water 6 flows into the check tube 108 from the funnel-shaped opening of the upper valve seat 110, and the drainage basin from the lower opening 64. It flows down toward the internal space of 122.

The height position where the sphere which is the check valve body 112 contacts on the funnel-shaped conical slope of the upper valve seat 110 is (−H ₅ ) below the reference position O of the artificial tidal flat filter bed 20. (−H ₅ ) is a position above (−H ₄ ) at the bottom surface position of the intermediate water tank 102. Therefore, even if the check tube 108 is opened and the treated water 6 in the internal space of the intermediate water tank 102 flows down to the internal space of the drainage table 122, the water level of the intermediate water tank 102 does not become lower than (−H ₅ ). However, the water level is lower than the reference position O of the artificial tidal flat filter bed 20. As a result, when the check tube 108 is opened and the treated water 6 in the inner space of the intermediate water tank 102 flows down to the inner space of the drainage table 122, the filter medium water level of the artificial tidal flat filter bed 20 is lowered to the reference position O. .

  A support stand 120 between the intermediate water tank 102 and the drainage stand 122 is a base member in which the communication pipe 104 is arranged and the water level pipe 106 and the check pipe 108 are penetrated and supported. The support table 120 may be a part of the intermediate water tank 102 or a part of the drainage table 122.

The drainage stand 122 is a waterproof box provided below the intermediate water tank 102. The upper surface of the drainage table 122 is covered with the support table 120, but the lower opening 58 of the water level pipe 106 and the lower opening 64 of the check pipe 108 are opened. A drainage portion 66 is provided on the lower side of one side surface of the outer wall of the drainage stand 122. The drainage stand 122 receives the treated water 6 flowing from the intermediate water tank 102 via the water level pipe 106 or the check pipe 108 when the filter medium water level of the artificial tidal flat filter bed 20 reaches the operation reference water level H _3. The waterproof box body is then drained from the drainage portion 66 to the outside.

  The triangular bucket 124 provided in the internal space of the drainage stand 122 is a water storage bucket that can rotate around the rotation center 126. The upper surface of the triangular bucket 124 that is open is disposed to face the lower opening 58 of the water level pipe 106. Dropped water 7 dripped from the lower opening 58 along the inner wall of the water level pipe 106 is received by the triangular bucket 124 and stored.

  The support column 130 that is fixedly installed on the upper edge of the intermediate water tank 102 is a lever support body that rotatably supports the lever body 134 at the rotation center 132 on the distal end side. The lever body 134 has one end of the tension rope 136 connected to one end with the rotation center 132 in between, and the weight 140 suspended from the other end via the weight suspension rope 138. On the other end side of the lever body 134, one end of the spherical suspension rope 142 is connected to an intermediate position between the rotation center 132 and the other end. The other end of the sphere suspension rope 142 is connected to a sphere that is the check valve body 112.

  The weight 140 is a lower return weight that rotates the lever body 134 around the rotation center 132 and pulls the other end downward when there is no tensile force from the tension rope 136. This state of the lever body 134 is referred to as a downward stable state. In the lower stable state of the lever body 134, the spherical suspension rope 142 is slightly loosened, and the spherical outer shape of the check valve body 112 is received by and contacted with the funnel-shaped conical slope of the upper valve seat 110. In FIG. 11, the state of each element in the downward stable state is indicated by a solid line.

  The other end of the tension rope 136 is connected to the tip of the triangular bucket 124 opposite to the rotation center 126. When the triangular bucket 124 is in an empty state where the dripping water 7 is not stored, the tension rope 136 is pulled by the weight 140 exclusively, and the lever body 134 is in a downward stable state in which the weight 140 settles at the lower position. Therefore, the tip of the triangular bucket 124 is pulled up by the tension rope 136, and the triangular bucket 124 is in a state where the dripping water 7 dripping from the lower opening 58 of the water level pipe 106 can be stored.

  The operation of the above configuration will be described with reference to FIG. Each figure of FIG. 12 is a figure which shows the relationship between the filter medium water level of the artificial tidal flat filter bed 20, and the effect | action of the pipe | tube non-return release mechanism 100. FIG.

12 (a) is a view corresponding to FIG. 10 (a) in the siphon tube mechanism 40, the filter medium water level of the artificial tidal flat filter bed 20 indicates when the H _29. The height of the upper opening 56 of the water level pipe 106 is set to the operation reference water level H ₃ , and H ₂₉ <H ₃ . Therefore, the treated water 6 does not flow into the water level pipe 106, and the triangular bucket 124 is empty. When the triangular bucket 124 is empty, the lever body 134 is in a downward stable state, the sphere suspension rope 142 is slightly loosened, and the sphere that is the check valve body 112 opens the upper opening of the upper valve seat 110 of the check pipe 108. Block it. As a result, the check tube 108 is cut off and the treated water 6 in the intermediate water tank 102 does not flow to the drainage stand 122.

FIG. 12B is a view corresponding to FIG. 10B in the siphon tube mechanism 40 and shows a state immediately before the filter medium water level of the artificial tidal flat filter bed 20 rises and reaches H ₃₀ . H ₃₀ is a water level corresponding to the height of the upper opening of the water level pipe 106 and is the operation reference water level H ₃ . In this state, the treated water 6 has not yet flowed into the water level pipe 106.

FIG. 12 (c), a diagram corresponding to FIG. 10 (c) in the siphon tube mechanism 40 indicates when the filter medium water level of the artificial tidal flat filter bed 20 becomes H ₃₁ beyond the H _30. Since H ₃₁ > H ₃ = H ₃₀ , the treated water 6 having a water level exceeding the operation reference water level H ₃ = H ₃₀ in the intermediate water tank 102 travels along the inner wall of the water level pipe 106 as the dropped water 7 as the lower opening 58. The water is received by the triangular bucket 124 inside the drainage stand 122 and stored. At this stage, the mass of the dripping water 7 accumulated in the triangular bucket 124 is still small, the tensile force of the tension rope 136 is insufficient, and the lever body 134 maintains the downward stable state.

  When the filter medium water level further rises from FIG. 12C and the treated water 6 continues to drip from the lower opening 58 as dripping water 7 along the inner wall of the water level pipe 106, dripping stored in the triangular bucket 124. The mass of the water 7 increases gradually.

  When the mass of the dripping water 7 stored in the triangular bucket 124 exceeds the threshold mass, the triangular bucket 124 rotates around the rotation center 126. When the triangular bucket 124 rotates, the tension rope 136, the lever body 134, the weight 140, the weight suspension rope 138, the sphere suspension rope 142, the position state of the sphere that is the check valve body 112, and the like change accordingly. In FIG. 11, the state after the change of these elements after the triangular bucket 124 is rotated is indicated by a two-dot chain line, and the sign of the element after the change is (+1) before the change.

  When the mass of the dropped water 7 stored in the triangular bucket 124 becomes equal to or greater than the threshold mass, the triangular bucket 125 shown in FIG. When the triangular bucket 124 is in the state of the triangular bucket 125, the tensile rope 136 is pulled toward the triangular bucket 125, and the tensile rope 137 is in the state. When the tension rope 136 becomes the tension rope 137, the lever body 134 rotates around the rotation center 132 against the mass of the weight 140, and the lever body 135 is brought into a state. Along with this, the weight suspension rope 138 becomes the state of the weight suspension rope 139, and the weight 140 rises in the vertical direction and becomes the state of the weight 141.

  When the lever body 134 is in the state of the lever body 135, the sphere suspension rope 142 is pulled up in the vertical direction to form the sphere suspension rope 143, and the sphere that is the check valve body 112 is the sphere that is the check valve body 113. It becomes the state of. In this state, the sphere as the check valve body 113 is separated from the upper valve seat 110 of the check tube 108. Accordingly, the upper valve seat 110 of the check pipe 108 is opened, and the treated water 6 flows toward the drainage table 122 through the check pipe 108. The treated water 6 that has flowed into the drainage table 122 is drained from the drainage part 66 of the drainage table 122 as the treated water 6.

Accordingly, the water level of the intermediate water tank 102 is lowered, and the filter medium water level of the artificial tidal flat filter bed 20 is also lowered through the communication pipe 104. In FIG. 12D, the lowered filter medium water level is indicated by H ₂₀ . Since the treated water 6 continues to flow from the check tube 108 toward the drainage stand 122, the filter medium water level further decreases as time passes. In this way, the filter medium water level of the artificial tidal flat filter bed 20 can be varied.

Since the opening position of the upper valve seat 110 of the check tube 108 is (−H ₅ ) below the reference position O of the artificial tidal flat filter bed 20, the filter medium water level of the artificial tidal flat filter bed 20 is lowered to the reference position O. And stop there. Thereby, all the treated water 6 in the artificial tidal flat filter bed 20 is drained from the drainage part 66 to the outside through the communication pipe 104, the intermediate water tank 102, the check pipe 108 and the drainage stand 122.

Until the mass of the dripping water 7 stored in the triangular bucket 124 exceeds the threshold mass and becomes the triangular bucket 125 state, the filter medium water level of the artificial tidal flat filter bed 20 hardly changes and is in a staying state. Dwell period T _S is the duration of the dwell state can be set storage capacity of the triangular bucket 124, the eccentric position of the rotation center 126 in a triangular bucket 124, the lever ratio in the lever 134, by the mass or the like of the weight 140. In addition, the lever ratio in the lever body 134 means that the length between the position where the weight suspension rope 138 is connected and the rotation center 132 along the longitudinal direction of the lever body 134 is L1, and the tension rope is connected. The length between the position and the rotation center 132 is L2 / L2, where L2.

The drainage period, which is a period required for the filter medium water level to drop to the reference position O from the state where the filter medium water level of the artificial tidal flat 20 is the operation reference water level H ₃ , corresponds to the intake period T ₂ described in FIG. . When it is desired to shorten the breathing period period T ₀ , the residence period T _S is shortened with respect to the inspiration period T ₂ . For example, the residence period T _S is preferably about 1% to 10% of the intake period T ₂ .

The intake period T ₂ in the artificial tidal flat filter bed 20 is a period required for the water level of the treated water 6 in the filter medium 30 to be lowered and drained. On the other hand, the expiration period T ₁ is a period until the water 4 to be treated penetrates the filter medium 30 and thereafter the water level in the filter medium 30 rises to the operation reference water level H ₃ . Due to this difference in mechanism, even if the filter bed thickness D is the same, in general, exhalation period T ₁ > inspiration period T ₂ . As an example, if the expiration period T ₁ = (2 × inspiration period T ₂ ), the expiration period T ₁ = 48 hours and the inspiration period T ₂ = 24 hours. The residence period T _S is 0.24 hours and about 15 minutes, assuming 1% of the intake period T ₂ . As a further example, assuming that the filter medium water level rises by 15 mm in about 15 minutes in the expiration period T ₁ , treated water 6 having a volume obtained by multiplying the filter medium area S of the artificial tidal flat filter bed 20 by about 15 mm passes through the water level pipe 106. Then, dripping water 7 is dropped into the triangular bucket 124. If other conditions are determined so that the mass of the dropped water 7 of this volume becomes the threshold mass of the triangular bucket 124, the desired residence time T _S can be obtained.

As described above, the pipe check opening mechanism 100 depends on the water level of the artificial tidal flat filter bed 20, and the pipe of the check pipe 108 provided between the water absorption part 54 and the drainage part 66 is opened from the blocked state. A check valve of a water level opening type transitioning to is provided. In the above example, the check valve transitions from the shut-off state to the open state at the timing when the water level of the artificial tidal flat filter bed 20 rises by about 15 mm from the operation reference water level H ₃ . Conduit check opening mechanism 100, if elapsed dwell period T _S is set by the mass or the like of the reservoir capacity and weight 140 of the triangular bucket 124, lowers the filter medium water level of the artificial tidal flat filter bed 20. Like the siphon tube mechanism 40, the residence period does not continue and the filter medium water level does not remain fixed.

The residence period T _S is also a period during which the expiration period T ₁ transitions to the inspiration period T ₂ . During the residence period T _S , the filter medium water level of the artificial tidal flat filter bed 20 remains fixed at the operation reference water level H ₃ , and no air is supplied from the atmosphere to the filter medium 30. Therefore, if the residence period T _S is lengthened, the expiration period T _{1 in} which the decomposition action by reduction is performed can be substantially extended. For example, in the artificial tidal flat filter bed 20 in which the expiration period T _{1 is set} to 48 hours and the inhalation period T ₂ is set to 24 hours, if the residence period T _S is set to 5 hours by increasing the retention period T _S , the effective expiration period Will be 53 hours.

  The water level opening type pipe check opening mechanism may be configured to electrically detect the amount of water stored in the triangular bucket 124 and operate an electric check valve according to the signal. In this case, an electric measuring device, an electric check valve, an electric control device, and the like are required, and a power source for operating them is required. Since the conduit check opening mechanism 100 of FIG. 11 is configured by a mechanical mechanism, it can be used even in an environment where power supply is difficult.

  2,3 Air, 4 Water to be treated, 6, 6a, 6b, 6e Treated water, 7 Drip water, 8 Final treated water, 10 Constructed wetlands, 11, 15 Structures, 12, 13 Staircase constructed wetlands, 14 layers Artificial wetland group, 16 water tank, 17 water supply pump, 18 water supply pipe, 20, 20a, 20b, 20c, 20d, 20e, 20f, 21a, 21b, 21c, 23a, 23b, 23c, 23d, 23e, 23f Artificial tidal flat filter Floor, 22 waterproof frame, 24 peripheral wall, 26 bottom surface, 28 top surface, 30, 30a, 30b, 30c, 30d, 30e, 30f, 32, 34 filter media, 40, 40a, 40b, 40c, 40d, 40e, 41a, 41b, 43a, 43b, 43c, 43d, 43e Siphon pipe mechanism, 48 (raw water) water supply unit, 48b, 48c, 48f, 49 Water supply unit, 50, 0a, 50b, 54 Water absorption part, 56 Upper opening, 58, 64 Lower opening, 60, 60a, 60b, 60e, 66 Drainage part, 62 Treatment port part, 70 Filter, 100 Pipe line non-return opening mechanism, 102 Intermediate water tank, 104 communication pipe, 106 water level pipe, 108 check pipe, 110 (check pipe) upper valve seat, 112, 113 (check pipe) check valve body, 120 support base, 122 drainage stand, 124, 125 triangle Bucket, 126, 132 Center of rotation, 130 Support pillar, 134, 135 Lever body, 136, 137 Tensile rope, 138, 139 Weight suspension rope, 140, 141 weight, 142, 143 Ball suspension rope.

Claims (8)

An artificial wetland for improving water quality that utilizes the microbial decomposition of organic matter and nutrients,
And artificial tidal filter bed Ru Tei is open upper surface and a biofilm or plant rhizosphere microorganisms is formed the peripheral wall portion comprises a filter medium having a predetermined filter medium thickness and the bottom portion is formed in the waterproof structure is the atmosphere side,
A water supply part for supplying water to be treated containing the organic matter and nutrients to the filter medium of the artificial tidal flat filter bed;
A drainage section for draining the treated water subjected to the decomposition action to the outside of the waterproof structure of the artificial tidal flat filter bed;
The water level in the artificial tidal flat is varied at a predetermined breathing period cycle, and fresh air is sucked into the filter medium from the atmosphere side in the period of water level descent for draining the treated water from the filter medium, and the filter medium performs the treatment A filter medium breathing mechanism for exhaling air that has been used in the decomposition action from the filter medium to the atmosphere side during a period of water level rise that permeates the target water;
Equipped with a,
The filter medium breathing mechanism is
Having a water absorption part at one end for absorbing water at a predetermined water absorption level measured from the reference position of the bottom surface of the waterproof structure;
The drainage portion drains at the drainage water level lower than the water absorption level at the other end,
A siphon pipe mechanism in which a part of the pipe line connecting the water absorption part and the drainage part is disposed at a height position of an operation reference water level higher than the water absorption water level,
The respiration period period can be adjusted by setting three conditions: the filter medium volume of the filter medium of the artificial tidal flat filter bed, the water penetration rate in the filter medium, and the operation reference water level of the siphon tube mechanism. as the same, as the filter media volume is large, the higher the permeation rate is low, as the operation reference water level is high, the breathing period cycle artificial wetland for water quality improvement, wherein Rukoto be set longer. An artificial wetland for improving water quality that utilizes the microbial decomposition of organic matter and nutrients,
An artificial tidal flat filter bed in which a biofilm or a plant rhizosphere microorganism group is formed and includes a filter medium having a predetermined filter medium thickness, a peripheral wall portion and a bottom surface portion are formed in a waterproof structure, and an upper surface portion is open to the atmosphere side;
A water supply part for supplying water to be treated containing the organic matter and nutrients to the filter medium of the artificial tidal flat filter bed;
A drainage section for draining the treated water subjected to the decomposition action to the outside of the waterproof structure of the artificial tidal flat filter bed;
The water level in the artificial tidal flat is varied at a predetermined breathing period cycle, and fresh air is sucked into the filter medium from the atmosphere side in the period of water level descent for draining the treated water from the filter medium, and the filter medium performs the treatment A filter medium breathing mechanism for exhaling air that has been used in the decomposition action from the filter medium to the atmosphere side during a period of water level rise that permeates the target water;
With
The filter medium breathing mechanism is
Having a water absorption part at one end for absorbing water at a predetermined water absorption level measured from the reference position of the bottom surface of the waterproof structure;
The drainage portion drains at the drainage water level lower than the water absorption level at the other end,
Until the water level of the water to be treated that has permeated the filter medium reaches a predetermined operation reference water level, the pipe portion connecting the water absorption part and the drainage part is blocked, and the water level of the treatment target water becomes the operation reference water level. reaches the conduit check opening mechanism der comprising a check valve in the water level open to open the conduit portion connecting said drain portion and the water absorbing portion is,
The breathing period cycle can be adjusted by setting three conditions: the filter medium volume of the filter medium of the artificial tidal flat filter bed, the water permeation rate in the filter medium, and the operation reference water level of the conduit check release mechanism, as same conditions as the filter media volume is large, the more the rate of water penetration in the filter medium is slow, as the operational reference water level is high, for the respiratory period cycle to improve water quality, wherein Rukoto be longer Artificial wetland. In the constructed wetland for water quality improvement according to claim 1 or 2 ,
In order to set the respiration period period of two artificial tidal flat filter beds having different filter medium volumes with the same permeation rate, the operation reference water level of the artificial tidal flat filter bed having a smaller filter medium volume is set. the operating reference level set high to artificial wetland for water quality improvement, wherein Rukoto of the artificial tidal filter bed towards the filter medium has a large volume. In the constructed wetland for water quality improvement according to claim 1 or 2 ,
For the two artificial tidal filter beds having different permeation speeds with the same operation reference water level, the permeation rate is slower than the respiration period cycle of the artificial tidal filter bed having the higher permeation rate. the artificial tidal the artificial wetland for water quality improvement, wherein Rukoto can set a respiratory period period longer filter bed. In the constructed wetland for water quality improvement according to claim 1 or 2 ,
A plurality of steps of the artificial tidal flat filter bed are arranged in a staircase to form a staircase artificial wetland group,
The raw water supply section for the stepped constructed wetland group is placed on the artificial tidal flat filter bed at the top of the stepped constructed wetland group,
Two sets of the artificial tidal flat filter beds adjacent to the stepped constructed wetland group are set as one set, and the filter medium breathing mechanism is arranged for each set, and the water absorption is placed on the artificial tidal flat filter bed on each upper set. The water supply part for the artificial tidal filter bed on the first lower stage side by disposing the drainage part of the filter medium breathing mechanism in which the part is disposed above the artificial tidal filter bed on the first lower stage side with respect to the upper stage side age,
An artificial wetland for water quality improvement, characterized in that a treatment port for draining the final treated water for the stepped artificial wetland group is provided in the artificial tidal flat filter bed at the bottom of the stepped artificial wetland group. In the constructed wetland for water quality improvement according to claim 1 or 2 ,
A plurality of the artificial tidal flats are stacked to form a multilayer constructed wetland group,
A raw water supply unit for supplying raw water that is the treatment target water for the multistory constructed wetland group is disposed on the artificial tidal flat filter bed at the top of the multistory constructed wetland group,
The two-stage artificial tidal flat filter beds adjacent to the multistory constructed wetland group are set as one set, and the filter medium respiration mechanism is arranged for each set, and the water absorption part is placed on the artificial tidal flat filter bed on each upper set side. The drainage part of the filter medium breathing mechanism in which the filter is disposed is disposed above the artificial tidal filter bed on the first lower stage with respect to the upper stage, and serves as the water supply part for the artificial tidal filter bed on the first lower stage side. ,
An artificial wetland for improving water quality, characterized in that a treatment port for draining final treated water for the multistory constructed wetland group is disposed on the artificial tidal flat filter bed at the bottom of the multistory constructed wetland group. In the artificial wetland for water quality improvement according to claim 6 ,
An artificial wetland for improving water quality, wherein the raw water supply section for the multistory artificial wetland group is a water supply pipe extending from the raw water reservoir through a water supply pump. In the constructed wetland for water quality improvement according to claim 1 or 2 ,
An artificial wetland for improving water quality, wherein the water absorption part is provided with a filter mechanism for suppressing suction of a filter medium.

Images