JP4560810B2 - Nitrate ion removal equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nitrate ion removal treatment apparatus to which a denitrification method using an autotrophic sulfur oxidative denitrification bacterium suitable for removing nitrate ions from agricultural wastewater, industrial wastewater, domestic wastewater or the like is applied.
[0002]
[Prior art]
In order to prevent environmental pollution caused by nitrate ions in various wastewaters, various treatment methods corresponding to this have been developed. Examples of the method for removing the nitrate ions include an autotrophic denitrification method using an autotrophic sulfur oxidative denitrification bacterium and a heterotrophic denitrification method using a heterotrophic denitrification bacterium. Among these, unlike the latter, the former is attracting attention in various directions because it does not require complicated maintenance such as quantitative addition of methanol and the cost.
[0003]
In particular, a method for removing nitrate ions using a sulfur oxidizing denitrifying bacterium using a mixed composition of sulfur and a calcium carbonate-containing substance (Japanese Patent Laid-Open No. 11-285377, Japanese Patent Laid-Open No. 2000-93997) as a denitrifying substrate is The system is excellent in that it can fully perform its functions, and the apparatus can be easily maintained, simplified in operation, and can realize a reliable denitrification process at low cost.
[0004]
However, denitrification with a mixed composition of sulfur and calcium carbonate containing substances using autotrophic sulfur oxidative denitrifying bacteria exhibits a function based on the conversion reaction from nitrate ions to nitrogen gas on the solid surface, Depending on external factors such as the inflow amount, flow state, flow rate, water temperature, viscosity, suspended suspension amount or coexisting ions of the treated water, nitrogen gas tends to adhere to the solid surface which is the denitrification substrate at the same time. When the amount of dissolved oxygen in the water to be treated is large, sulfur is oxidized regardless of denitrification, and the denitrification efficiency may be lowered.
[0005]
When a large amount of the nitrogen gas adheres to the surface of the denitrification substrate as bubbles, the surface renewal function of the solid denitrification substrate decreases, and the denitrification efficiency is reduced by slowing the conversion reaction from nitrate ions to nitrogen gas. A decrease may be seen.
[0006]
Conventionally, as a denitrification device, it is provided on the upper side of the water supply pipe 1 and the exhaust pipe 2 processing tank 3 as shown in Figure 1 2, a plurality of rectifying plates 4a and Chigae the height of the water surface alternately , 4b ... are disposed in the tank of the treatment tank 3, and the waste water W is meandered by the rectifying plates 4a, 4b ... There has been proposed (Japanese Patent Laid-Open No. 11-104689).
[0007]
This denitrification equipment is suitable for heterotrophic denitrification, especially denitrification by the activated sludge method, and is suitable for autotrophic denitrification using a sulfur-containing material as a filter medium from the viewpoint of contact efficiency between the water to be treated and the filter medium. Absent.
[0008]
Other denitrification apparatus described above, attached to a plurality of rectifying plates 4a, 4b ... are positioned inside the filter material bed by sulfur-containing filter medium S provided in a bath of the processing tank 3 as shown in Figure 1 3, The thing which can be applied to autotrophic denitrification by letting the to-be-processed water W pass through the inside of a filter-medium bed is also proposed.
[0009]
In this denitrification apparatus, when a denitrification method comprising the above-mentioned mixed composition of sulfur and alkaline substance and autotrophic sulfur oxidative denitrifying bacteria is used, a rectifying plate is possible because it is necessary to increase the reaction efficiency. It is necessary to arrange as many as possible, and the amount of dissolved oxygen increases when the water to be treated comes into contact with the air many times on the surface of the water. As a result, sulfur is oxidized outside of the denitrification reaction, resulting in denitrification efficiency. It will fall.
[0010]
In addition, if the amount of daily drainage fluctuates within a certain range depending on the weather and the growth stage of crops, such as hydroponic drainage, a large-capacity drainage storage container may be placed separately or a small human Control or automatic control is required.
[0011]
[Problems to be solved by the invention]
The present invention suppresses the influence of external factors such as the inflow amount, flow state, flow rate, water temperature, viscosity, suspended suspension amount or coexisting ions of the water to be treated, and sulfur is oxidized other than in the denitrification reaction. It is an object of the present invention to provide a nitrate ion removal treatment apparatus that can effectively prevent denitrification and exhibit a denitrification function efficiently.
[0012]
At the same time, it is an object of the present invention to provide a nitrate ion removal treatment apparatus that can contribute to high efficiency and stabilization of the treatment speed even when the amount of daily wastewater varies greatly.
[0013]
[Means for Solving the Problems]
In the nitrate ion removal treatment apparatus of the invention according to claim 1 of the present application, a denitrification method using an autotrophic sulfur oxidative denitrification bacterium is applied, and a filter medium bed made of granular or massive sulfur-containing filter medium is placed in the tank. In addition, a water supply piping system that feeds the water to be treated into the tank is disposed in the lower part of the tank below the filter medium bed , and the upper end of the pipe that rises in the tank above the filter medium bed opens, and an outflow hole for treated water is formed. An overflow pipe provided on the peripheral side near the upper end of the pipe is provided in the piping system for controlling the discharge of treated water, and a drain piping system for sending treated water from the filter medium bed to the outside of the tank is arranged above the tank above the filter medium bed. It is configured as a water treatment tank of an upward flow type in which water to be treated flows from the lower side of the filter medium bed toward the upper side.
[0014]
In the nitrate ion removal treatment apparatus of the invention according to claim 2 of the present application, a plurality of water discharge holes that are opposed to the floor bottom of the filter medium bed and are scattered within the area of the floor bottom are used for dispersion water supply of the treated water. It is comprised by providing the water supply piping system provided in the piping in a tank as.
[0015]
In the nitrate ion removal processing apparatus of the invention according to claim 3 of the present application, a filter medium bed composed of a mixed composition of sulfur and an alkaline substance is provided in the tank, and is located between particles of the mixed composition of sulfur and an alkaline substance. This is configured by setting the oxidation-reduction potential of the water to be treated and / or the oxidation-reduction potential in the tank to 0 mV to -300 mV.
[0016]
In the nitrate ion removal processing apparatus of the invention according to claim 4 of the present application, the distance between the uppermost part of the filter medium bed and the water surface of the water to be treated or treated water is set to 30 mm or more.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, mainly explaining based on the embodiment of FIG. 1 , the illustrated nitrate ion removing apparatus includes a filter medium bed 10 with a sulfur-containing filter medium S using autotrophic sulfur oxidative denitrifying bacteria in a tank. The feed water piping system 11 for feeding the treated water W ₁ into the tank is disposed at the lower part of the tank below the filter medium bed 10, and the drain pipe system 12 for sending the treated water W ₂ to the outside of the tank is above the filter medium bed 10. by disposing the tank top, and is configured as a water treatment tank 13 of the upflow mode to flow upward to the water to be treated W ₁ from the lower side of the filter medium bed 10.
[0018]
For the sulfur-containing filter medium S, it is most suitable to use a mixed composition of sulfur and an alkaline substance. This filter medium S uses a granular material or a massive material in which sulfur and a substance mainly composed of calcium carbonate (alkaline substance) coexist as a denitrifying substrate of autotrophic sulfur oxidative denitrifying bacteria. The denitrification substrate is obtained by heating and melting sulfur to solidify by cooling after mixing sulfur and an alkaline substance or by crushing or granulating the solid (Japanese Patent Laid-Open No. 11-285377). ).
[0019]
Further, sulfur and an alkaline substance can be used as a denitrification substrate by coexisting a substance having fine pores in a main composition (Japanese Patent Laid-Open No. 2000-93997). The fine pore materials include diatomaceous earth, diatomaceous earth burned material, tuff, olivine, perlite, pearlite, porous ceramic, brick, ALC, pumice, pozzolana, shirasu, shirasu balloon, expanded shale fired product, attabargite, sepiolite, cristobalite. Mineral products or processed products such as sericite, acid clay, illite, etc., or charcoal such as charcoal, coconut husk charcoal, rice husk charcoal, coal, bamboo charcoal, activated carbon, etc. are used.
[0020]
The composition of the denitrification substrate can be mixed with a third component such as various rock powders, soil, or rock wool. As an alkaline substance, things which do not contain calcium carbonate, such as steel slag and lightweight cellular concrete crushed material, may be used. The autotrophic sulfur-oxidizing bacteria are not particularly limited, and sulfur-oxidizing denitrifying bacteria that exist in general nature (Thiobacillus denitrificans) and the like are used.
[0021]
The sulfur-containing filter medium S is granular or massive and is deposited in a tank to form the filter medium bed 10. However, there are no particular restrictions on the amount and particle size of the mixed composition of sulfur and alkaline substance, the filling thickness in the tank, and the like.
[0022]
The filter medium bed 10 is provided with a receiving bottom 14 in the tank by filling and depositing the sulfur-containing filter medium S in the tank bottom, or a perforated double pipe (container) or an expanded metal that can pass the water to be treated. If necessary, an in-tank water temperature maintaining device (not shown) is provided at the bottom of the tank, and the sulfur-containing filter medium S is received and deposited inside the bottom 14 of the tank.
[0023]
The water supply piping system 11 and the drainage piping system 12 can be disposed by attaching a round tubular pipe member communicating with the inside and outside of the water treatment tank 13 to the side wall. In view of installation efficiency, the water treatment tank 13 is desirably configured in a cylindrical shape shown in FIG. 2 or a rectangular parallelepiped shape not particularly shown, and a semi-sealed structure that can be opened and closed with a lid, a door, or the like. However, the denitrified nitrogen gas outlet is arbitrarily secured. The diameter, height, material and thickness of the water treatment tank 13 are not particularly limited, and can be freely designed according to the type and amount of water to be treated, the discharge frequency, and the like.
[0024]
The nitrate ion removal treatment device configured in this way is installed so that it is directly connected to a drainage source such as agricultural wastewater, industrial wastewater, or household wastewater, or introduced through a storage tank. It can be installed to introduce wastewater by gravity due to difference or pumping by pump.
[0025]
The waste water, that is, the water to be treated W ₁ is fed into the tank from the water supply piping system 11 disposed at the lower part of the tank, and flows upward in the tank from the lower side of the filter medium bed 10. In the course of this flow, in the presence of autotrophic sulfur oxidative denitrifying bacteria, the treated water W ₁ passes through the solid surface of the sulfur-containing filter medium S, so that nitrate ions on the solid surface of the sulfur-containing filter medium S are converted into nitrogen. The denitrification function based on the conversion reaction to gas can be sufficiently exerted.
[0026]
Furthermore, since by applying an upward flow type to flow upward to the water to be treated W ₁ from below, various inorganic wastewater passes through the filter medium bed 10 is to remove process nitrate ions, to be treated It is not easily affected by external factors such as water inflow, flow state, flow rate, water temperature, viscosity, suspended suspension amount or coexisting ions, and nitrogen gas adheres to the solid surface as a denitrification substrate at the same time. Therefore, the increase of new dissolved oxygen can be suppressed, and the denitrification efficiency can be improved because sulfur is not oxidized regardless of the denitrification.
[0027]
The process water W ₂ may be Okuridase from waste water pipe system 12 which is disposed above the tank above the filter medium bed 10 as waste removal or reduction filter media bed 10 of nitrate outside the tank. This can greatly contribute to prevention of environmental pollution caused by nitrate ions in various wastewaters.
[0028]
The above-described water supply piping system 11 is provided with an in-tank piping 11a, and a plurality of water discharge holes 11b, 11b... That are opposed to the floor bottom of the filter medium floor 10 and are scattered within the floor bottom area are treated water W _1. It is good to equip the piping system provided in the piping 11a in the tank for the distributed water supply. In the tank the pipe 11a, the water to be treated W ₁ a plurality of water discharge holes 11b, are 11b ... widely dispersed in from the tank is efficiently supplied pass filter medium bed 10. It is also possible to omit the in-tank piping 11a and the water discharge holes 11b, 11b... By replacing the perforated receiving bottom 14 with the in-tank piping 11a and the water discharge holes 11b, 11b.
[0029]
The in-tank pipe 11a is formed into a hollow disk-like body as shown in FIG. 2 according to the tank shape of the water treatment tank 13, and is formed into a hollow square disk-like body (not shown). Can be. In addition, various shapes or structures can be formed as described later.
[0030]
Drainage to the pipe system 12, the tube upper end is open, processed water W ₂ of outlet holes 12b, 12b ... tube upper end side of the peripheral side surface arranging a plurality longitudinally of treated water W ₂ which is provided with overflow pipe 12a As shown in FIG. 1, a water tank is provided in the tank above the filter medium bed 10 for adjusting the drainage. Its downcomers 12a is intended for closing the tube lower end, gradually flows out treated water _{W 2} outlet holes 12b, from 12b .... Thus, it is effectively act-treatment water W ₁ 0.00 long residence time of the water to be treated W ₁ in the sulfur-containing filter medium S. Incidentally, regulation of the residence time of the water to be treated W ₁ is outlet hole 12b of the waterproof tape or the like, if necessary, easily the like pasted 12b ....
[0031]
In the downcomers 12a, because the tube and the upper end is opened, also the water to be treated exceed the capacity of the water treatment tank 13 is introduced in a short time, the filter medium bed 10 treated water W ₂ which nitrate ions are reduced The waste water can be sent out from the upper end of the pipe, and can respond to fluctuations in the amount of treated water without water level sensors, solenoid valves, or human management.
[0032]
As for the overflow pipe 12a, the distribution range of the outflow holes 12b, 12b... Is limited for discharge adjustment, but the hole shape, diameter, number, diameter, installation site, length, material, thickness, etc. of the pipe are There is no restriction, and it can be designed according to the type and amount of water to be treated, the discharge frequency, etc. Further, together with the overflow pipe 12a, the retention time and introduction of the water to be treated are also obtained depending on the structure of the water treatment tank 13 so as to ensure a large volume of the water treatment tank 13 as a horizontally long plane as shown in FIGS . 3a and 3b. Can be designed to handle volume fluctuations.
[0033]
In the above-described embodiment, when a sulfur-containing filter medium comprising a mixed composition of sulfur and an alkaline substance is used, the oxidation-reduction potential of water to be treated between the particles of the mixed composition of sulfur and an alkaline substance and / or The oxidation-reduction potential (Eh) in the tank may be set to 0 mV to -300 mV, preferably -50 mV to -250 mV. Thereby, the environment suitable for sulfur denitrification is obtained.
[0034]
Specifically, when Eh is higher than −50 mV (plus side), the reduction condition is insufficient, and when Eh is more than 0 mV, the oxidation condition is reached, and sulfur is oxidized by sulfur-oxidizing bacteria other than denitrification. . On the other hand, when Eh is lower than −300 mV (minus side), particularly lower than −500 mV, a strong reducing atmosphere is formed, and iron sulfide may be deposited on the surface of the sulfur-containing filter medium S.
[0035]
In order to obtain the good Eh condition, it is also necessary to secure a distance of at least 30 mm between the surface height of the filter medium bed 10 and the water surface height of the treated water W ₁ or the treated water W ₂ . Thereby, the environment suitable for sulfur denitrification is obtained reliably.
[0036]
As mentioned above, although main embodiment of this invention was described, the water supply piping system 11 is provided with the tank piping 11a of the shape thru | or structure described below. As a modified example, although the shape differs depending on the planar shape of the water treatment tank 13 formed of a cylindrical body or a rectangular tubular body, a common type of both of them may be mentioned.
[0037]
As a modification thereof, a ring shape in which a plurality of branch pipes extend in a ring shape from the root tube 11c as shown in FIGS . 4a and 4b , or a spiral shape that continues in a spiral shape from the root tube 11c as shown in FIGS . 5a and 5b. 6a and 6b , a branch type in which a plurality of branches extend from the root tube 11c, and a fork type in which a plurality of branches as shown in FIGS . 7a and 7b extend from near the root tube, shown in FIGS . 8a and 8b. Such a plurality of branches extending in parallel from the root tube 11c, a meandering type continuous from the root tube 11c as shown in FIGS . 9a and 9b , and annular from the root tube 11c as shown in FIGS . 10a and 10b Examples include a ring type that extends, and a net type that protrudes in a net shape from the root tube 11c as shown in FIGS . 11a and 11b .
[0038]
In addition, the waste water pipe system 12 of the water supply pipeline 11 and the process water W ₂ of the water to be treated W ₁ showed a treated water introduced and the treated water discharge of the apparatus form of a series, for example, the scale of each device configuration change Thus, two devices arranged in parallel, symmetrically arranged, or three or more devices can be arranged. In this case, the waste water pipe system of the feed water pipe system and treated water W ₂ of the for-treatment water W ₁ may be provided plural in one processing unit.
[0039]
In order to check the validity of the above-mentioned nitrate ion removal apparatus of the invention, with the device shown in Figure 13, it was carried out the following experiment. The apparatus according to the present invention and the apparatus shown in FIG. 13 are equipped with several types of water treatment tanks having different capacities, charged with 70 kg of a sulfur / calcium carbonate mixed composition having a particle size of 5 to 20 mm, and nitrate nitrogen: about 200 mg / L of water to be treated (hydroponic culture wastewater) was passed at a water temperature of 20 to 30 ° C. and a flow rate of 140 L / day, and the time-dependent change of the nitrate nitrogen removal treatment status was examined.
[0041]
[Example 1]
In the apparatus having the overflow pipe shown in FIG . 3a and FIG. 3b, a cuboid treatment tank with a capacity of 500L is provided, and the water to be treated is passed at a flow rate of 50 to 600L / day, so When the change with time was confirmed, the nitrate nitrogen concentration of the treated water was reduced to an average of about 5 mg / L even after 14 days after the start of the denitrification treatment, even when the flow rate was 600 L / day.
[0042]
[Comparative Example 1]
In the apparatus having no overflow pipe shown in FIG. 13 , a cuboid treatment tank with a capacity of 500 L is provided, 300 kg of a sulfur / calcium carbonate mixed composition having a particle size of 5 to 20 mm is filled, and the water to be treated is supplied at a flow rate of 50 to 600 L / Water was passed in a range of days, and the time-dependent change in the nitrate nitrogen removal treatment status was confirmed. After 14 days from the start of the denitrification treatment, the average concentration of nitrate nitrogen in the treated water was about 50 mg when the flow rate was 450 L / day or more. / L. This is because when the water flow rate is 450 L / day or more, untreated water also flows out from the treated water discharge port at the same time, and the residence time in the apparatus to be treated is short. At a flow rate of 300 L / day or less, the nitrate nitrogen concentration of the treated water was reduced to about 5 mg / L or less.
[0043]
Further, in the apparatus according to the present invention and the apparatus shown in FIG. 13, a water treatment tank having a capacity of 100 L, a particle size: 5-20 mm sulfur / calcium carbonate mixed composition: 50 kg is loaded, and the uppermost part of the filter medium bed The water to be treated or the distance between the water surfaces of the treated water is changed, and the total amount of nitrate nitrogen and nitrite nitrogen is about 14 mg / L of treated water (single septic tank treated water = sewage treated water, chlorinated water) ) Was passed at a water temperature of 12 to 16 ° C. and a flow rate of 250 to 300 L / day, and the change with time of removal of nitrate nitrogen and nitrite nitrogen was confirmed.
[0044]
[Example 2]
In the apparatus according to FIGS . 1 and 2, when water was passed from the top of the filter medium bed with a cylindrical treatment tank having a water surface distance of 400 mm, nitrate nitrogen and nitrous acid remaining in the denitrification treated water were passed. The total concentration of nitrate nitrogen was 0 to 0.4 mg / L. In addition, the amount of sulfate ions produced as a by-product remained at 67-96 mg / L in the treated water, compared to about 33-40 mg / L in the treated water. The treated hydroxide reduction potential between the sulfur / calcium carbonate mixed composition particles at this time was about -180 mV on average. The sulfate ion produced as a by-product is instantly neutralized by the sulfur / calcium carbonate mixed composition, so there is no problem.
[0045]
[Comparative Example 2]
In the apparatus shown in FIG. 13, nitrate nitrogen remaining in the denitrification treated water is passed from the uppermost part of the filter medium bed with a rectangular parallelepiped treatment tank having a water surface distance of 0 to 20 mm. In addition, the total amount of nitrite nitrogen remained about 5 to 10 mg / L. Further, the amount of sulfate ions produced as a by-product was about 33 to 40 mg / L in the water to be treated, and 60 to 87 mg / L in the treated water. The treated hydroxide reduction potential between the sulfur and calcium carbonate mixed composition particles at this time was about +20 mV on average. The sulfate ions produced as a by-product are instantly neutralized by the sulfur / calcium carbonate mixed composition, so there is no problem, but dissolved oxygen supplied from a plurality of water surfaces has caused a decrease in denitrification efficiency.
[0046]
【The invention's effect】
As described above, according to the nitrate ion removal processing apparatus of the invention according to claim 1 of the present application, the denitrification method using autotrophic sulfur oxidative denitrification bacteria is applied. By converting the nitrate ion to nitrogen gas on the solid surface of the sulfur-containing filter medium by configuring the floor as a water treatment tank of the upward flow method in which the water to be treated flows from the bottom to the top of the filter medium bed Denitrification function based on the reaction can be fully exerted, and it is not easily affected by external factors such as the inflow amount, flow state, flow rate, water temperature, viscosity, suspended suspension amount or coexisting ions of water to be treated. It is possible to prevent the gas from adhering to the solid surface as a denitrification substrate in a large amount at the same time, and to suppress the increase of new dissolved oxygen. Since sulfur is not oxidized regardless of denitrification, the denitrification efficiency can be improved.
[0047]
In addition , a drainage piping system having an overflow pipe with an outflow hole provided on the peripheral side near the upper end of the pipe, which is open at the upper end of the pipe in the tank above the filter medium bed , for controlling the discharge of the treated water. By installing it, the residence time of the treated water can be adjusted rationally, allowing the treated water to effectively act on the sulfur-containing filter medium, and even if a large amount of treated water is introduced in a short time, the opening at the upper end of the pipe It can be discharged without difficulty from the department.
[0048]
According to the nitrate ion removal processing apparatus of the invention according to claim 2 of the present application, a plurality of water discharge holes which are opposed to the floor bottom of the filter medium bed and are scattered within the floor bottom area are dispersed in the water to be treated. By providing the water supply piping system provided in the tank piping for water supply, the water to be treated is dispersed widely in the tank through the plurality of water discharge holes, and can be efficiently supplied to the filter medium bed.
[0049]
According to the nitrate ion removal treatment apparatus of the invention of claim 3 of the present invention, a filter medium bed comprising a mixed composition of sulfur and an alkaline substance is provided in the tank, and particles of the mixed composition of sulfur and an alkaline substance are provided. By setting the oxidation-reduction potential of the water to be treated and / or the oxidation-reduction potential in the tank to 0 mV to -300 mV, it is possible to prevent wasteful consumption of sulfur by sulfur-oxidizing bacteria. An environment suitable for sulfur denitrification can be obtained because a reducing atmosphere can be prevented and deposition of iron sulfide or the like on the surface of the filter medium can be prevented.
[0050]
According to the nitrate ion removing treatment apparatus of the invention according to claim 4 of the present application, by setting the distance between the uppermost part of the filter medium bed and the water surface of the treated water or treated water to 30 mm or more, sulfur denitrification The environment suitable for is surely obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a nitrate ion removal treatment apparatus having a cylindrical body treatment tank in a preferred embodiment of the present invention.
FIG. 2 is an explanatory view showing the nitrate ion removal process of FIG. 1 in cross section.
FIG. 3a is an explanatory view showing a nitrate ion removal treatment apparatus including a square tube treatment tank in a preferred embodiment of the present invention.
FIG. 3b is an explanatory view showing the nitrate ion removing process of FIG. 3a in a cross section.
FIG. 4a is an explanatory view showing a ring-shaped tank internal pipe for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 4b is an explanatory view showing a pipe in a ring-shaped tank for a square tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 5a is an explanatory diagram showing a spiral tank internal pipe for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 5b is an explanatory diagram showing a spiral tank internal pipe for a square tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 6A is an explanatory view showing a branching tank internal pipe for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 6b is an explanatory diagram showing a branch-type tank piping for a square tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 7a is an explanatory diagram showing a fork-type tank internal pipe for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 7b is an explanatory view showing a fork-type tank internal pipe for a rectangular tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 8a is an explanatory view showing a pipe in a comb tank for a cylindrical body treatment tank provided in a water supply piping system of a nitrate ion removal treatment apparatus according to the present invention.
FIG. 8b is an explanatory diagram showing a comb-type tank internal pipe for a square tube processing tank provided in a water supply pipe system of the nitrate ion removing apparatus according to the present invention.
FIG. 9a is an explanatory view showing meandering tank piping for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 9b is an explanatory view showing a meandering-type tank piping for a rectangular tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 10a is an explanatory diagram showing a ring-type tank piping for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 10b is an explanatory view showing a ring-type tank piping for a rectangular tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 11a is an explanatory diagram showing a mesh-type tank piping for a cylindrical body processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 11b is an explanatory diagram showing a mesh-type tank piping for a square tube processing tank provided in a water supply piping system of a nitrate ion removal processing apparatus according to the present invention.
FIG. 12 is an explanatory view showing a denitrification apparatus according to a conventional example.
FIG. 13 is an explanatory view showing a conventional denitrification apparatus according to another example.
[Explanation of symbols]
W ₁ Treated water W ₂ Treated water S Sulfur-containing filter medium 10 Filter medium floor 11 Water supply piping system 11a Water supply piping system tank piping 11b Water discharging hole of tank piping 12 Drain piping system 12a Drain piping system overflow pipe 12b Overflow Pipe drain hole 13 Water treatment tank

Claims (4)

A nitrate ion removal treatment apparatus to which a denitrification method using autotrophic sulfur oxidative denitrification bacteria is applied, and a filter medium bed made of granular or massive sulfur-containing filter medium is provided in the tank, and water to be treated is fed into the tank. Overflow with the water supply piping system installed in the lower part of the tank below the filter medium bed, the upper end of the pipe rising in the tank above the filter medium bed is open, and the outflow hole for treated water is provided on the peripheral side near the upper end of the pipe There is a pipe in the piping system for controlling the discharge of treated water, and a drain piping system for sending treated water from the filter medium bed to the outside of the tank is installed in the upper part of the tank above the filter medium bed, and the treated water is placed below the filter medium bed. A nitrate ion removing apparatus, characterized in that it is configured as an upward-flow type water treatment tank that flows upward from the top.   A water supply piping system provided with a plurality of water discharge holes, which are opposed to the floor of the filter media floor and scattered within the area of the floor, is provided in the piping in the tank for the distributed water supply of the water to be treated. The nitrate ion removal processing apparatus according to claim 1. A filter medium bed comprising a mixed composition of sulfur and an alkaline substance is provided in the tank, and the redox potential of the water to be treated between the particles of the mixed composition of sulfur and the alkaline substance and / or the redox potential in the tank is 0 mV. The nitrate ion removing apparatus according to claim 1 or 2 , wherein the apparatus is set to -300 mV. The nitrate ion removal treatment apparatus according to claim 3 , wherein the distance between the uppermost part of the filter medium bed and the surface of the treated water or the treated water is set to 30 mm or more.

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