JP2004181274A - Method for removing nitrogen by using string-like fiber assembly and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of obtaining treated water by removing nitrogen by a simple treatment process without the need for adding methanol to the water. <P>SOLUTION: The method for removing the nitrogen comprises storing the water 10 to be treated into a storage section 2 for the water to be treated having an anaerobic atmosphere in the interior 7 thereof, dipping a filter member 3 composed of the assembly of a plurality of string-like fiber assemblies disposed in the storage section for the water to be treated into the water to be treated to form a microorganism colony 1 and allowing the treated water 8 to flow out of the filter member in the state that the water is controlled to the oxidation reduction potential of a prescribed range in such a manner that the dissolution of the ammonia nitrogen is little and organic materials are well dissolved in the microorganism colony. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for removing nitrogen using a filtration member comprising a string-like fiber aggregate, and particularly to remove nitrogen contained in wastewater to prevent eutrophication of rivers and lakes. The present invention relates to a method for denitrifying and obtaining clean treated water and an apparatus therefor.
[0002]
[Prior art]
Taking a typical activated sludge method among the wastewater treatment methods as an example, in this case, raw water such as domestic wastewater is allowed to flow into an aeration tank, and water treatment is performed using a high concentration of microorganisms in the aeration tank. I have.
However, nitric acid nitrogen (NO₃If -N) is contained, if this water is discharged to rivers and lakes as it is, it will cause water pollution due to eutrophication.
[0003]
Therefore, as a technique for removing nitrogen in wastewater, for example, Non-Patent Document 1 discloses a biological nitrogen removal method for removing nitrogen from wastewater, a methanol addition method in which an organic carbon source such as methanol is added, and a circulation method. Is described.
However, in both cases of the methanol addition method and the circulation method, a sedimentation tank and the like are provided, and sludge is returned, so that the treatment process becomes complicated and sophisticated operation technology is required.
Further, in the methanol addition method, it is necessary to always supply methanol for removing nitrogen, so that maintenance work is difficult and costly. On the other hand, in the circulation method, nitrification is performed after removing nitrogen (meaning oxidization of ammonia nitrogen to nitrite or nitrate nitrogen). Therefore, nitrification is inhibited and nitrogen removal becomes difficult. Had become.
In either case, sludge is separated in the sedimentation tank, and filtration is not performed. Therefore, solid-liquid separation is not sufficient, and it is difficult to obtain clean treated water.
As a related art of the present invention, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-263408) describes a water treatment method using a filtration member composed of a string-like fiber aggregate and an apparatus therefor. There is no description on the removal of
[0004]
[Non-patent document 1]
"Maintenance of septic tanks" published by Japan Environmental Education Center, March 1986, p. 449-451
[Patent Document 1]
JP-A-2002-263408 (page 1, FIG. 9)
[0005]
[Problems to be solved by the invention]
The present invention has been made to solve such a problem, and it is not necessary to add methanol or the like for removing nitrogen, and it is possible to obtain clean treated water by removing nitrogen in a simple treatment process. It is an object of the present invention to provide a method for removing nitrogen using a string-like fiber aggregate and an apparatus therefor.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a nitrogen removing method using a string-like fiber aggregate according to the present invention is a method for removing nitrogen from a nitrogen-containing water to be treated, wherein the inside of the water to be treated has an anaerobic atmosphere. Storing the water to be treated in the storage part, immersing a filtration member provided in the water to be treated storage part constituted by a collection of a plurality of string-like fiber aggregates in the water to be treated to form a microbial colony, In the microbial colony, the treated water was allowed to flow out of the filtration member in a state where the redox potential was controlled within a predetermined range so that the ammonia nitrogen was less dissolved and the organic matter was dissolved well.
A nitrogen removing device using a string-like fiber aggregate suitable for carrying out this method is a nitrogen removing device for removing nitrogen from treated water containing nitrogen, wherein the treated water is stored and the inside is anaerobic. Treatment water storage part of a neutral atmosphere, a filtration member provided in the treatment water storage part, configured by a collection of a plurality of string-like fiber aggregates, and the oxidation-reduction potential of the treated water flowing out from the filtration member. And an oxidation-reduction potential adjusting means for adjusting, wherein the filtration member is immersed in the water to be treated to form a microbial colony, and in this microbial colony, ammonia-based nitrogen is less dissolved and organic matter is well dissolved. The treated water is allowed to flow out of the filtration member while being controlled to a predetermined range of oxidation-reduction potential by the oxidation-reduction potential adjusting means.
[0007]
A method according to a specific embodiment is a method for removing nitrogen from treated water containing nitrogen, the method comprising: storing the treated water in a treated water storage section having an anaerobic atmosphere therein; A part or almost all of the filtering member provided in the storage part and constituted by a collection of a plurality of elongated string-like fiber aggregates is immersed in the water to be treated, and the water to be treated is immersed in the water of the filtering member due to a difference in water level. By entering the interstices between the fibers from the entire surface, small groups of microorganisms that cannot enter the interstices of the fibers adhere to the surface of the string-like fiber aggregate in a pipe shape, and the water to be treated is Flowing through the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the fiber assembly, the small group of microorganisms attached in a pipe shape on the surface of the string-like fiber assembly gradually becomes large and becomes minute inside. Has a clearance function with a gap After that, the water to be treated is filtered where it enters the microscopic gap inside the microbial colony, and then flows through the microscopic gap due to the difference in water level. The treated water is controlled to a predetermined range of oxidation-reduction potential so as to flow by the pressure gradient and to dissolve ammonia nitrogen in the microbial colonies less and to dissolve organic matter well and to form a suitable anaerobic state. In this state, the water flows out of the filtration member and is discharged to the outside of the treated water storage part.
A preferred and specific nitrogen removing apparatus for carrying out this method is a nitrogen removing apparatus for removing nitrogen from the water to be treated containing nitrogen, wherein the water to be treated is stored and the inside of which is treated in an anaerobic atmosphere. A water storage part, a filtration member provided in the water storage part to be treated, a part or substantially all of which is immersed in the water to be treated, and a filtration member constituted by a collection of a plurality of elongated string-like fiber aggregates; A treated water discharging means for discharging treated water flowing out of the apparatus, and an oxidation-reduction potential adjusting means for adjusting the oxidation-reduction potential of the treated water, wherein the water to be treated is provided with By entering the gap between the fibers from the entire surface immersed in water, a small group of microorganisms that cannot enter the gap between the fibers adheres to the surface of the string-like fiber aggregate in a pipe shape, and the water to be treated is The longitudinal direction of the cord-like fiber aggregate Flow through the interfiber gap due to the pressure gradient generated, the small population of microorganisms attached in a pipe shape to the surface of the string-like fiber aggregate gradually increases and has a fine gap inside and is filtered. After forming a microbial colony that exhibits a function, the water to be treated is filtered where it enters the microscopic gap inside the microbial colony, and then flows through the microscopic gap due to the water level difference. The treated water flows through the gap by the pressure gradient, and in the microbial colonies, the treated water is adjusted to the oxidation-reduction potential adjustment so that the ammonia nitrogen is less dissolved and the organic matter is dissolved in a favorable anaerobic state. In the state where the oxidation-reduction potential is controlled within a predetermined range by the means, the water flows out of the filtration member and is discharged to the outside of the treated water storage unit by the treated water discharging means. It was.
In the above method and apparatus, it is preferable that the oxidation-reduction potential of the treated water is controlled in a range of -120 mV to +50 mV.
Preferably, the concentration of the solid in the microbial colony is 3% by weight to 5% by weight.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment according to the present invention will be described with reference to FIGS.
In the present embodiment, the nitrogen removal method and apparatus according to the present invention are treated with a typical activated sludge method among sewage treatment methods to form nitrate nitrogen (NO₃-N) will be described by way of example.
[0009]
The method and apparatus of the present invention treats raw water (water before treatment supplied to a nitrogen removal device) having a relatively low concentration of suspended solids (SS) to produce clean treated water (treated water). Also used to get. For example, when river water or lake water (raw water) taken from rivers and lakes is treated at a waterworks to make it clean (drinking water), when well water (raw water) is treated to make clean water, the pool water (Raw water) for processing and recycling, precision processing using ultra-fine fibers, processing equivalent to processing in sedimentation tanks and sand filtration equipment of wastewater treatment equipment, and fish cultivation To purify the water in the culture pond. In addition, the present invention is also applicable to a septic tank for sewage treatment of a house.
[0010]
FIG. 1 is a schematic configuration diagram of a nitrogen removing apparatus using a string-like fiber assembly, FIG. 2 (A) is an explanatory view showing a filtering member composed of the string-like fiber assembly, and FIG. 2 (B) is a string-like shape. It is an expanded sectional view of a fiber aggregate.
3 (A) and 3 (B) are a plan view and a front view, respectively, showing a state where the filtering member shown in FIG. 2 is sewn in a circle, and FIG. 4 (A) is a longitudinal section showing the filtering member and treated water discharging means. FIG. 4B is a sectional view taken along line BB of FIG. 4A, and FIG. 5 is a partially enlarged sectional view of FIG. 4A.
FIG. 6A is a diagram corresponding to a micrograph of a state in which a small group of microorganisms has begun to adhere to a string-like fiber aggregate, and FIG. 6B is a diagram in which small groups of microorganisms gather to form a microbial colony. It is a figure corresponding to the micrograph of the state where it began to do.
[0011]
As shown in FIGS. 1 to 6, the method of removing (denitrifying) nitrogen from the water to be treated 10 containing nitrogen involves storing the water to be treated 10 in the water to be treated storage section 2 having an anaerobic atmosphere 7. The filtration member 3 provided in the water-to-be-treated storage section 2 and constituted by a collection of a plurality of string-like fiber aggregates 6 is immersed in the water to be treated 10 to form microbial colonies 11.
Then, the treated water 8 is filtered in a state where it is controlled to a predetermined range of oxidation-reduction potential (hereinafter referred to as ORP) so that the ammonia-based nitrogen is less dissolved and the organic matter is favorably dissolved in the microbial colony 11. It flows out of the member 3.
The nitrogen removing apparatus 1 for removing nitrogen from the water to be treated 10 for carrying out this method includes a water to be treated storage part 2 in which the water to be treated 10 is stored and the inside of which is an anaerobic atmosphere; And a redox potential adjusting means 5 for adjusting the ORP of the treated water 8 flowing out of the filtering member 3. .
Then, the filtration member 3 is immersed in the water 10 to be treated to form a microbial colony 11, and the treated water 8 has an oxidation-reduction potential such that the ammonia-based nitrogen is less dissolved in the microorganism colony 11 and the organic matter is well dissolved. It flows out of the filtering member 3 in a state where the ORP is controlled to a predetermined range by the adjusting means 5.
[0012]
The nitrogen removal method according to a more specific embodiment is characterized in that the water to be treated 10 is stored in the water to be treated storage 2 having an anaerobic atmosphere 7 therein, and a plurality of elongated strings provided in the water to be treated storage 2 are provided. Part or almost all of the filtration member 3 formed by the collection of the fiber aggregates 6 is immersed in the water 10 to be treated, and the water 9 is removed from the entire surface of the filtration member 3 where the water 10 is immersed in the water due to the water level difference H. By entering the gap between the fibers, a small group of microorganisms (aggregates of microorganisms, also called flocs) that cannot enter the gap between the fibers adheres to the surface of the string-like fiber aggregate 6 in a pipe shape, and 10 flows through the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the string-like fiber aggregate 6, and the small population of microorganisms attached to the surface of the string-like fiber aggregate 6 in a pipe shape gradually increases. Filter with a small gap inside Microbial colonies exhibiting (a visible agglomerates of microorganisms, for example, colonies of activated sludge) to form a 11.
Thereafter, the water to be treated 10 is filtered where it enters a minute gap inside the microbial colony 11, and then flows through the minute gap by the water level difference H, and then flows through the gap between the fibers by a pressure gradient.
Then, in the microbial colony 11, the treated water 8 is filtered under a predetermined range of ORP such that the ammonia nitrogen is less dissolved and the organic matter is dissolved well and a suitable anaerobic state is obtained. And is discharged to the outside of the water-to-be-treated storage unit 2.
[0013]
A preferred and specific nitrogen removing apparatus 1 for performing this method has a function of removing nitrogen from the water to be treated 10 containing nitrogen. The nitrogen removal device 1 is provided in the treated water storage unit 2 in which the treated water 10 is stored and the inside 7 has an anaerobic atmosphere, and a part or almost all of the treated water 10 is stored in the treated water 10. A filtration member 3 formed by a set of a plurality of elongated string-like fiber aggregates 6 soaked, treated water discharge means 4 for discharging treated water 8 flowing out from the filtration member 3, An oxidation-reduction potential adjusting means 5 for adjusting ORP is provided.
The plurality of string-like fiber aggregates 6 constituting the string-like filtration member 3 are composed of a large number of fibers 9. In the string-like fiber assembly 6, the fibers 9 are entangled with each other, and a narrow gap is formed between the fibers 9. Also, a small gap is formed between the fiber 9 of the string-like fiber assembly 6 and the fiber 9 of the other string-like fiber assembly 6. The gaps between these fibers constitute a pseudo fine tube similar to a fine tube.
[0014]
In the nitrogen removing device 1, the water to be treated 10 enters the gap between the fibers 9 from the entire surface of the filter member 3 immersed in water due to the water level difference H, so that the small population 30 of microorganisms that cannot enter between the fiber gaps The to-be-processed water 10 adheres in a pipe shape to the surface of the string-like fiber aggregate 6 and flows through the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the string-like fiber aggregate 6. The small group 30 of microorganisms adhered in the shape of a pipe to the surface of the substrate gradually grows to form microbial colonies 11 having a minute gap 31 therein and exhibiting a filtering function.
Thereafter, the water to be treated 10 is filtered where it enters the microscopic gap 31 inside the microbial colony 11, flows through the microscopic gap 31 by the water level difference H, and then flows through the interfiber gap by the pressure gradient.
In the microbial colony 11, the treated water 8 is controlled to a predetermined range of ORP by the oxidation-reduction potential adjusting means 5 so that the ammonia nitrogen is less dissolved and the organic matter is dissolved well and the anaerobic state is good. In this state, the water flows out of the filtration member 3 and is discharged to the outside of the treated water storage unit 2 by the treated water discharge means 4.
[0015]
By supplying the water to be treated 10 via the supply pipe 12 by a pump or the like, the water level La of the water to be treated 10 in the water to be treated storage 2 is maintained at a predetermined height position.
The to-be-processed water storage part 2 is provided with a stirrer 17 for stirring the stored to-be-processed water 10. The stirrer 17 stirs the water 10 by slowly rotating the blades 17a so that the small group 30 of microorganisms and the microbial colony 11 adhering to the filtration member are not broken or separated from the filtration member 3.
The treated water storage unit 2 is provided with an air supply unit 13. The air supply unit 13 controls the ORP of the treated water 8 within a predetermined range by discharging air 18 from a nozzle 19 near the bottom surface of the treated water storage unit 2.
A treated water storage section 12 for storing the treated water 8 is provided downstream of the treated water storage section 2. The water level Lc of the treated water 8 in the treated water storage unit 12 is lower than the water level La of the water 10 to be treated. The treated water storage unit 12 receives and stores the treated water 8 discharged from the filtration member 3 and flowing through the treated water discharge means 4.
[0016]
The treated water discharge means 4 has a filtration member support 15 provided in the treated water storage 2 and a discharge pipe 14 connected to the filtration member support 15. Inside the filtration member support portion 15, a water guide portion 16 in which the treated water 8 flows in communication with the filtration member 3 is formed.
The discharge pipe 14 communicates with the water guide 16, guides the treated water 8 flowing through the water guide 16 to the outside of the treated water storage 2, and discharges the treated water 8 to the treated water storage 12. The treated water 8 flowing out of the filtering member 3 flows through the water guide 16 and the discharge pipe 14 and is stored in the treated water storage 12.
[0017]
The nitrogen removal device is provided with a water level difference adjusting means so that the water level difference H can be adjusted.
The discharge port 14 a of the discharge pipe 14 is immersed in the treated water 8 in the treated water storage unit 12. The water level difference H in this case is from the downstream water level of the treated water 8 (that is, the water level Lc of the treated water 8 in the treated water storage unit 12) to the water level La of the treated water 10 in the treated water storage unit 2. Is the height dimension. That is, the water level difference H = water level La−water level Lc. The water level difference H can be adjusted by the water level difference adjusting means.
Separately from this, the discharge port 14a of the discharge pipe 14 may be located above the water surface of the treated water storage unit 12 and located above the water level, and the discharge port 14a may be located below the water level La of the water 10 to be treated. (Not shown).
The water level difference H in this case is the height dimension from the downstream water level Lb of the treated water 8 (that is, the height position of the water surface in the discharge pipe 14 near the discharge port 14a) to the water level La of the water 10 to be treated. It is. That is, the water level difference H = water level La−water level Lb.
[0018]
The water to be treated 10 flows naturally due to the energy at the position due to gravity based on the water level difference H serving as the driving source (energy source) of the flow and the cohesive force between the water molecules, and is treated from the treated water storage 2. It moves to the water storage unit 12.
That is, since the filtration member 3 has the pseudo fine tube constituted by the inter-fiber gap, the water to be treated 10 in the water to be treated storage section 2 is generated in the longitudinal direction of the string-like fiber aggregate 6. Flows through the pseudo fine tube due to the pressure gradient.
The water to be treated 10 contains a large amount of suspended solids larger than the inside diameter of the pseudo fine tube. Therefore, among the suspended solids contained in the water 10 to be treated, suspended solids larger than the inner diameter of the pseudo fine tube cannot pass through the pseudo fine tube. Therefore, the suspended solids adhere to the filtering member 3 and are removed. This filtration is performed in the water to be treated 10 stored in the treated water storage unit 2.
As described above, the size of the suspended solids to be removed is determined by the inner diameter of the pseudo fine tube. Therefore, according to the type, size, particle size distribution, etc. of the suspended solids contained in the water 10 to be treated, the selection of the optimum material of the filtering member 3 and the size, density, etc. of the string-like fiber aggregate 6 and the fiber 9 are determined. Just do it.
[0019]
The oxidation-reduction potential adjusting means 5 for controlling the ORP of the treated water 8 within a predetermined range includes the air supply unit 13, the detector 21, and the air 18 by controlling the air supply unit 13 based on a signal from the detector 21. And a control unit (not shown) that adjusts the flow rate.
The detector 21 is provided in the discharge pipe 14 and detects the ORP of the treated water 8 flowing out of the filtration member 3. By adjusting the flow rate of the air 18 supplied into the water 10 to be treated by the air supply unit 13 based on the signal output from the detector 21, the ORP of the treated water 8 flowing through the discharge pipe 14 can be adjusted to a predetermined value. , For example, in the range of -120 mV to +50 mV.
Further, the range of the concentration of solid matter (that is, sludge) in the microbial colony 11 is preferably 3% by weight to 5% by weight.
If the temperature of the water to be treated 10 in the water to be treated storage unit 2 is low, the activity of the microorganisms is reduced. However, if the temperature of the water to be treated 10 is within a predetermined range (preferably 23 ° C. ± 7 ° C.), And the nitrogen removal is satisfactorily performed.
Therefore, the nitrogen removing device 1 has a water temperature adjusting means 22 for adjusting the water temperature of the water 10 to be treated to a predetermined range. The water temperature adjusting means 22 can control the heater 23 provided in the water to be treated 10 of the water to be treated storage 2 to control the temperature of the water to be treated 10 to, for example, 23 ° C. ± 7 ° C. It is.
[0020]
The filtering member 3 is composed of a plurality of elongated string-like fiber aggregates 6. That is, the filtering member 3 is configured in a “border shape” by the string-like fiber aggregate 6 composed of only the warp yarn. One string-like fiber aggregate 6 is formed by combining a plurality of warp yarns in which a large number of fine fibers 9 are gathered.
As described above, the string-like filtration member 3 is less likely to be clogged because the plurality of string-like fiber aggregates 6 are gathered into an interdigital shape.
The composition of the filtering member 3 is preferably selected from at least one of synthetic fibers such as polyester synthetic fiber, rayon and acrylic fiber. For example, the filtering member 3 is composed of about 40% by weight of a polyester synthetic fiber, about 40% by weight of rayon, and about 20% by weight of an acrylic fiber.
In addition, you may use the following high molecular compounds as a raw material of the filtration member 3. For example, ethyl cellulose, cellulose acetate, nylon, vinylon, acetate, cupra, acrylonitrile, polyethylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polystyrene, polytetrafluoroethylene, polyterephthalate ethylene, polytrifluoroethylene, poly Examples thereof include chlorotrifluoroethylene, polyvinyl alcohol, polypropylene, and polymethyl methacrylate.
[0021]
The filtering member 3 has a stitching portion 40 for making the plurality of string-like fiber aggregates 6 into a flat bundle. In the stitching portion 40, the string-like fiber aggregates 6 are loosened without being compressed, so that even when the treated water 8 flows inside the stitching portion 40, the treated water 8 can easily pass therethrough.
The diameter e (FIG. 2B) of the string-like fiber aggregate 6 is appropriately selected according to the type, size, particle size distribution, and the like of the microorganism, and is, for example, about 3 mm to about 4 mm in diameter e.
As shown in FIGS. 3A and 3B, the filtering member 3 is formed into a circular shape by sewing both ends 40a and 40b of the stitched portion 40 together as shown in FIGS. Have been. Note that, in FIG. 3B, illustration of a part of the string-like fiber aggregate 6 is omitted.
[0022]
An annular band 45 is attached to the outer peripheral surface of the annularly formed sewing portion 40. The band 45 holds the stitched portion 40 in an annular shape and prevents the string-like fiber aggregate 6 from being loosened.
Using the stitched portion 40 and the band 45 as support portions, the string-like fiber aggregates 6 on one side and the string-like fiber aggregates 6 on the other side are used by being turned back so as to spread radially outward.
The string-like fiber aggregate 6 in the present invention includes, in addition to those shown in the present embodiment, a thread-like fiber aggregate having a small diameter, and a fiber aggregate including a warp and a slight weft. Further, for example, a case where a cloth-like nonwoven fabric or the like is cut into small pieces to form a string-like fiber aggregate having a slightly wide width and an elongated shape may be used.
[0023]
The filtration member support portion 15 is a pipe-shaped support tube 41 that is disposed vertically in the center and has a closed lower end, a hollow holder 42 that is supported by the support tube 41, and has an upper end and a lower end closed respectively. have.
A plurality of communication holes 48 are formed in the support tube 41. An annular holding portion 46 for holding the support tube 41 at the center position is formed integrally with the holder 42, and a plurality of communication holes 47 are formed in the holding portion 46.
[0024]
The filtering member 3 is attached to the opening of the holder 42 so that there is no gap. Thereby, since the internal space 49 of the holder 42 is shielded from the water 10 to be treated in the water to be treated storage part 2 by the filtration member 3, a short path of the water to be treated can be prevented.
The inner space 49 and the inner space of the support tube 41 constitute the water guide 16 through which the treated water 8 flows.
The water 10 to be treated is treated by the filtration member 3. The treated water 8 flowing out of the filtering member 3 enters the internal space 49 of the holder 42 and then passes through the communication hole 47 into the support tube 41 through the communication hole 48 or directly passes through the communication hole 48 from the internal space 49. Into the support tube 41. Thereafter, the treated water 48 is discharged from the support pipe 41 to the outside of the treated water storage unit 2 through the discharge pipe 14.
[0025]
FIG. 5 shows one string-shaped fiber aggregate 6 among a plurality of string-shaped fiber aggregates 6 as an example.
When no solid matter (microbial colony 11) is attached to the string-like fiber aggregate 6, most of the water to be treated 10 is at the root of the string-like fiber aggregate 6 due to gravity based on the water level difference H. By entering the gap between the fibers 9 from the entire surface of the string-like fiber assembly 6 immersed in water by the energy of the position, a small group 30 of microorganisms that cannot enter between the fiber gaps is placed on the surface of the string-like fiber assembly 6. The to-be-treated water 10 adheres in a pipe shape and flows through the inter-fiber gap due to a pressure gradient generated in the longitudinal direction of the string-like fiber aggregate 6.
As time passes, a small group 30 of microorganisms adheres to the surface of the string-like fiber aggregate 6 in a pipe shape, and the small group 30 of microorganisms gradually grows and becomes a microbial colony 11 composed of activated sludge (adhered solid matter). To form
The string-like fiber aggregate 6 to which the microbial colonies 11 adhere and are surrounded has a structure like a pseudo pipe (or honeycomb) constituted by a plurality of inter-fiber gaps. Inside the microbial colony 11, a minute gap 31 that exerts a filtering function is formed.
Therefore, the water to be treated 10 flows through the gap in the pseudo pipe by the energy of the position due to gravity based on the water level difference H and the cohesive force between the water molecules. Further, the water to be treated 10 flows through the minute gaps 31 inside the microbial colonies that exhibit the filtering function due to the water level difference H.
[0026]
The water 10 to be treated is filtered at the gap between the fibers 9 from the entire surface of the string-like fiber aggregate 6 due to the water level difference H. The water to be treated 10 flows in the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the string-like fiber aggregate 6.
Further, the water to be treated 10 is also filtered where it enters the minute gap 31 inside the microbial colony 11 having a filtering function, flows through the minute gap 31 due to the water level difference H, and then pressurizes the gap between the fibers. It flows by the gradient.
Thereby, the water to be treated 10 becomes the treated water 8 and flows into the internal space 49 of the holder 42. Since the water to be treated 10 flows through the gaps between the fibers 9 due to the pressure gradient, it can continue to flow even if the size of the attached microbial colonies 11 increases.
[0027]
Next, an experiment performed by the inventor will be described. The experimental conditions are as follows.
Composition of the filter member 3: 40% by weight of polyester synthetic fiber, 40% by weight of rayon, 20% by weight of acrylic fiber
・ Dimensions of filtering member 3 (when deployed): about 43 cm (width D) x about 30 cm (length E)
String-like fiber aggregate 6: diameter e is about 4 mm
・ Capacity of treated water storage unit 2: 1m³
-Filtration member support 15: 2 sets of 3 sets (1 set) with one holder of about 2 m in length
・ Water to be treated 10: Water after treatment by activated sludge method at sewage treatment center
・ Flow rate of water to be treated: 3.9m³/Day
・ Experiment period: 2 days
[0028]
When one holder 42 having a length of about 2 m is used as the filtration member supporting portion 15, two sets of three sets (one set) (that is, a total of six sets) are installed in the treated water storage section 2. , And connected to the discharge pipe 14 in parallel.
4.8 kg (dry) of sludge is charged into the treated water storage section 2 after storing the treated water 10, and the filtration member 3 sucks up the sludge to form microbial colonies 11. An experiment on nitrogen removal was performed.
The water treated by the activated sludge method at the sewage treatment center in Ibaraki Prefecture is used as raw water (water to be treated 10), 3.9m³The raw water flowed into the treated water storage unit 2 at a flow rate of / day. The average residence time in the treated water storage unit 2 was 6.15 Hr.
The water temperature of the water 10 to be treated in the treated water storage unit 2 is adjusted to a range of 23 ° C. ± 7 ° C. by turning on and off the heater 23 by the water temperature adjusting means 22.
The nitrogen removal state (denitrification state) includes nitrite and nitrate nitrogen (NO₂+ NO₃ ⁻-N). FIG. 7 is a diagram showing an example of experimental data relating to the removal of nitrogen. FIG. 8 shows BOD (biochemical oxygen demand) of treated water 8 and ammonia nitrogen (NH₄It is a graph which shows an example of the density of -N). The horizontal axis in FIG. 8 indicates the ORP of the treated water 8, and the vertical axis indicates the concentration. Curve A in FIG. 8 shows BOD, and curve B shows NH₄−N is indicated.
[0029]
In the nitrogen removal apparatus 1 used in this experiment, the water to be treated 10 is stored in the water to be treated storage section 2 having an anaerobic atmosphere inside, and the entire filtering member 3 provided in the water to be treated storage section 2 is covered. It is immersed in treated water 10.
A predetermined flow rate of the water to be treated 10 is supplied to the water to be treated storage section 2 via a supply pipe 12. As a result, the water level La of the treated water 10 in the treated water storage unit 2 is higher than the water level Lc of the treated water 8 in the treated water storage unit 12, so that the water level difference H is secured.
[0030]
Due to the water level difference H, the water to be treated 10 enters the gap between the fibers 9 from the entire surface of the filter member 3 immersed in water, and the small group 30 of microorganisms that cannot enter between the fiber gaps becomes a string-like fiber aggregate. The to-be-processed water 10 adheres to the surface of the body 6 in a pipe shape, and flows through the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the string-like fiber aggregate 6 (the state of FIG. 6A).
Thus, the small group 30 of microorganisms attached to the surface of the string-like fiber aggregate 6 in a pipe shape gradually grows to form the microorganism colonies 11. The microbial colony 11 has a minute gap 31 inside and exhibits a filtering function (the state of FIG. 6B).
The dimensions of the gaps between the fibers 9 (eg, about 20-30 μm inner diameter), the dimensions of the microbial particles (eg, about 1-2 μm), and the dimensions of the minute gaps 31 inside the microbial colony 11 (eg, Can be confirmed by a micrograph.
[0031]
After that, the water to be treated 10 is filtered where it enters the microscopic gap 31 inside the microbial colony 11, flows through the microscopic gap 31 by the water level difference H, and then flows through the interfiber gap by the pressure gradient.
The treated water 8 flows out of the filtration member 3 and is discharged to the outside of the treated water storage section 2 in a state where the ORP is controlled to a predetermined range by the oxidation-reduction potential adjusting means 5. That is, the treated water 8 flows from the filtration member 3 to the internal space 49 of the holder 42, the interior of the support tube 41, and the discharge pipe 14 in this order, and is stored in the treated water storage unit 12.
Since the ORP of the treated water 8 is preferably measured before the treated water 8 comes into contact with air, the ORP is measured at a position immediately after the treated water 8 is discharged from the treated water storage unit 2.
[0032]
The ORP of the treated water 8 can be increased or decreased by increasing or decreasing the flow rate of the air 18 supplied by the air supply unit 13. When the supply amount of the air 18 is reduced and the ORP of the treated water 8 is reduced, the BOD of the treated water 8 is increased as shown by a curve A in FIG. This means that if the ORP of the treated water 8 is reduced, the organic matter of the microorganism is dissolved in the treated water 8 in the microorganism colony 11.
When such dissolution of organic matter occurs in the microbial colony 11, the remaining microorganisms eat the organic matter as food. Moreover, since microorganisms need oxygen to breathe, they take in oxygen by decomposing nitric acid contained in water flowing through the minute gaps 31 inside the microorganism colony 11.
The nitric acid in the water flowing through the minute gap 31 is thus decomposed into oxygen and nitrogen, so that nitrogen is removed from the water. In addition, since microorganisms eat dissolved organic matter as food, there is no need to add an organic carbon source such as methanol which has been added by a conventional methanol addition method or the like.
As shown by the curve A in FIG. 8, when the ORP of the treated water 8 was +50 mV or less, it was confirmed that the organic matter was dissolved well and was particularly effective in removing nitrogen.
[0033]
On the other hand, NH in the treated water 8₄Regarding -N (ammonia-based nitrogen), as shown in a curve B in FIG. 8, when the ORP of the treated water 8 decreases and becomes anaerobic, the ammonia-based nitrogen (NH₄−N) is increasing. This means that in the microbial colony 11, dissolution of ammonia nitrogen has occurred and decay has started.
When the ammonia nitrogen is dissolved in the treated water 8 and the nitrogen is increased, the purpose of the nitrogen removal is defeated. This ammonia nitrogen is particularly large when the ORP of the treated water 8 is in the range of -120 mV or less.
[0034]
To summarize the above experimental results, the conditions under which the dissolution of ammonia nitrogen in the microbial colony 11 is small and the organic matter is well dissolved and the anaerobic state is good are as follows: ORP of the treated water 8 is in the range of -120 mV to +50 mV It can be seen that it is preferable to control
At this time, the concentration of solid matter (concentration of sludge) in the microbial colony 11 is 3% by weight to 5% by weight, and the temperature of the water 10 to be treated in the treated water storage unit 2 is in the range of 23 ° C. ± 7 ° C. For example, nitrogen was successfully removed.
As for the ORP of the treated water 8, the flow rate of the air 18 is adjusted by controlling the air supply unit 13 based on the value of the ORP of the treated water 8 detected by the detector 21. Thereby, the ORP of the treated water 8 can be controlled.
Increasing the water level difference H increases the concentration of the solid, and decreasing the water level difference H decreases the concentration of the solid. Therefore, if the water level difference H is adjusted by the water level difference adjusting means, the concentration of the solid can be controlled.
Further, the water temperature adjusting means 22 turns on and off the heater 23 so that the water temperature of the water to be treated 10 in the water to be treated storage section 2 can be controlled within a range of 23 ° C. ± 7 ° C.
[0035]
By operating the nitrogen removing apparatus 1 as described above, it is possible to remove nitrogen from the water to be treated 10 and obtain clean treated water 8. FIG. 7 shows the concentrations and removal rates of nitrite and nitric acid in the raw water (the water to be treated 10) and the treated water 8. In this experiment, the average removal rate was 63.6%, and it was confirmed that nitrogen could be removed well.
In this way, since clean wastewater can be discharged by removing nitrogen in the wastewater, eutrophication of rivers and lakes can be prevented, and the water quality can be improved.
[0036]
In the conventional nitrogen removal technology, microorganisms are always suspended in the entire tank in an anaerobic atmosphere, and the concentration of suspended solids composed of such microorganisms cannot be so high. 0.5% was the upper limit of the concentration.
On the other hand, in the present invention, the microbial colonies 11 are formed on the filtering member 3, and water flows through the minute gaps 31 in the microbial colonies 11. Since the microbial colony 11 is also a place where the microorganisms live, the microorganisms can stay at substantially the same position without floating in the tank.
Thus, when the microbial colony 11 is formed, the sludge (microorganism) stays at substantially the same place, so that the concentration of the sludge in the microbial colony 11 can be significantly increased as compared with the conventional method.
[0037]
Further, in the microbial colony 11, there is a sufficient amount of organic matter serving as food for the microbes, necessary oxygen is constantly supplied by water flowing through the minute gaps 31, and the microbial concentration is significantly higher than before (for example, , About 10 times higher than before).
Therefore, the microorganisms can live in a stable state in the microorganism colony 11, and nitrogen is removed in a biologically favorable state. Further, in the microbial colony 11, since the microorganisms eat dissolved organic matter as food and consume the sludge, it is not necessary to remove the sludge, and there is a possibility that the treatment of the sludge which becomes industrial waste becomes unnecessary. high.
[0038]
In the past, in the anaerobic atmosphere, the floating organisms in the water were in contact with the nitrogen component, or were in contact with the nitrogen component on the surface of the biofilm, but in the present invention, the contact structure in which water passes through the inside of the microbial colony 11 Therefore, the chance of contact increases, and nitrogen can be removed with higher efficiency.
In the conventional circulation method, the removal of nitrogen inhibits nitrification. However, in the present invention, since there is no inhibition of nitrification, nitrogen can be easily removed.
For example, if the present invention is applied to a waterworks installed in a water intake source area to obtain clean water (drinking water), nitrogen can be easily removed without adding chemicals to the collected water, Water quality can be improved.
[0039]
ADVANTAGE OF THE INVENTION According to this invention, the substance (sludge) which becomes an industrial waste can be made into a natural circulation form by further promoting the food chain of living things, energy saving, the facility can be simplified, and Can greatly reduce the cost of social life and contribute to society.
Since the filtering member 3 and the microbial colony 11 perform the filtering function, the conventionally required sedimentation tank and the like become unnecessary, and the sludge does not need to be returned. Therefore, the treatment process is simplified, and solid-liquid separation is sufficiently performed without separately providing a filtration device, so that clean treated water 8 can be obtained.
[0040]
In the present invention, the nitrogen removing device 1 of the present invention can be easily configured by adding a filter member support portion 15 to which the filter member 3 is attached in the treated water storage portion 2 having an anaerobic atmosphere inside. it can.
In the present embodiment, the movement of the water to be treated 10 and the treated water 8 is due to the energy at the position due to gravity based on the water level difference H serving as the driving source (energy source) of the flow and the cohesive force between the water molecules. No power was used during this time. Also, there is no need to circulate water.
Therefore, compared with the conventional water treatment technology, the power is smaller, so that the energy consumption of the water treatment device can be reduced, the noise hardly occurs, and the operation is easy because the treatment process is simple.
[0041]
In addition, although the case where the whole of the filtering member 3 is immersed in the to-be-processed water 10 was shown, the case where not the whole of the filtering member 3 but most of the filtering member 3 is immersed in the to-be-processed water 10 may be sufficient.
In addition, although the case where the filter member supporting portion 15 is arranged in a substantially vertical direction (vertical direction) as a whole is shown, the case where the filter member supporting portion 15 is arranged in a direction inclined with respect to the vertical direction (oblique direction) may be employed.
[0042]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications and additions can be made within the scope of the present invention.
In the drawings, the same reference numerals indicate the same or corresponding parts.
[0043]
【The invention's effect】
Since the present invention is configured as described above, it is not necessary to add methanol or the like for removing nitrogen, and clean treated water can be obtained by removing nitrogen in a simple treatment step.
[Brief description of the drawings]
FIGS. 1 to 8 show an example of an embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of a nitrogen removing apparatus.
FIG. 2 (A) is an explanatory view showing a filtering member made of a string-shaped fiber aggregate, and FIG. 2 (B) is an enlarged sectional view of the string-shaped fiber aggregate.
3 (A) and 3 (B) are a plan view and a front view showing a state where the filtering member shown in FIG. 2 is sewn in a circular shape.
4 (A) is a longitudinal sectional view showing the filtration member and the treated water discharging means, and FIG. 4 (B) is a sectional view taken along line BB of FIG. 4 (A).
FIG. 5 is a partially enlarged sectional view of FIG.
FIG. 6A is a diagram corresponding to a micrograph of a state in which a small group of microorganisms has begun to adhere to a string-like fiber aggregate, and FIG. 6B is a diagram in which a small group of the microorganisms is gathered. It is a figure corresponding to the micrograph of the state where the microbe colony began to form.
FIG. 7 is a diagram showing an example of experimental data on nitrogen removal.
FIG. 8 is a graph showing an example of the concentrations of BOD and ammonia nitrogen in treated water.
[Explanation of symbols]
1 Nitrogen removal equipment
2 treated water storage
3 Filtration member
4 Treated water discharge means
5 Redox potential adjusting means
6 string fiber aggregate
8 Treated water
9 Fiber
10 Water to be treated
11 Microbial colonies
30 Small group of microorganisms
31 Minute gap
H water level difference

Claims (8)

A method for removing nitrogen from treated water containing nitrogen,
The treated water is stored in the treated water storage part having an anaerobic atmosphere inside,
A microbial colony is formed by immersing a filtration member, which is provided in the water-to-be-treated storage part, and constituted by a collection of a plurality of string-like fiber aggregates in the water to be treated,
In this microbial colony, the treated water is caused to flow out of the filtration member in a state where the treated water is controlled to a predetermined range of oxidation-reduction potential so that the ammonia nitrogen is less dissolved and the organic matter is favorably dissolved. A nitrogen removal method using a string-like fiber aggregate. A method for removing nitrogen from treated water containing nitrogen,
The treated water is stored in the treated water storage part having an anaerobic atmosphere inside,
A part or almost the entirety of a filtration member formed by a collection of a plurality of elongated string-like fiber aggregates provided in the water to be treated is immersed in the water to be treated,
Due to the water level difference, the water to be treated enters the gap between the fibers from the entire surface of the filter member immersed in water, so that a small population of microorganisms that cannot enter between the fiber gaps is on the surface of the string-like fiber aggregate. Attached in a pipe shape, the to-be-processed water flowed through the inter-fiber gap due to a pressure gradient generated in a longitudinal direction of the string-shaped fiber aggregate, and adhered in a pipe shape to the surface of the string-shaped fiber aggregate. The small population of microorganisms gradually grows to form microbial colonies that exhibit a filtering function with small gaps inside,
Thereafter, the water to be treated is filtered where it enters the microscopic gap inside the microbial colony, and then flows through the microscopic gap due to the water level difference, and then flows through the interfiber gap by the pressure gradient. ,
In the microbial colony, the treated water is filtered from the filtration member in a state where the dissolution of ammonia nitrogen is small and the organic matter is dissolved in a favorable anaerobic state so as to be in a favorable anaerobic state. A method for removing nitrogen using a string-like fiber aggregate, wherein the nitrogen is discharged and discharged to the outside of the treated water storage part. The method according to claim 1 or 2, wherein the oxidation-reduction potential of the treated water is controlled in a range of -120 mV to +50 mV. 4. The method of claim 1, wherein a concentration of solids in the microbial colony is 3% by weight to 5% by weight. 5. A nitrogen removing device for removing nitrogen from treated water containing nitrogen,
The treated water is stored, and the treated water storage portion has an anaerobic atmosphere inside,
A filtration member provided in the water-to-be-treated storage part and configured by a set of a plurality of string-like fiber aggregates,
An oxidation-reduction potential adjusting means for adjusting the oxidation-reduction potential of the treated water flowing out of the filtration member,
The filtration member is immersed in the water to be treated to form a microbial colony.In this microbial colony, the treated water is treated by the oxidation-reduction potential adjusting means so that the dissolution of ammonia nitrogen is small and the organic matter is well dissolved. A nitrogen removal device using a string-like fiber aggregate, wherein the nitrogen-removal device is made to flow out of the filtration member in a state where the oxidation-reduction potential is controlled within a predetermined range. A nitrogen removing device for removing nitrogen from treated water containing nitrogen,
The treated water is stored, and the treated water storage portion has an anaerobic atmosphere inside,
A filtration member provided in the treated water storage part, a part or almost all of which is immersed in the treated water, and constituted by a collection of a plurality of elongated string-like fiber aggregates,
Treated water discharge means for discharging treated water flowing out of the filtration member,
An oxidation-reduction potential adjusting means for adjusting the oxidation-reduction potential of the treated water,
The water to be treated enters the gaps between the fibers from the entire surface of the filter member immersed in water due to the difference in water level. The to-be-treated water flows through the inter-fiber gap due to the pressure gradient generated in the longitudinal direction of the string-like fiber aggregate, and adheres in a pipe-like manner to the surface of the string-like fiber aggregate. The small population of the microorganisms gradually grows to form microbial colonies that exhibit a filtering function with small gaps inside,
Thereafter, the water to be treated is filtered where it enters the microscopic gap inside the microbial colony, and then flows through the microscopic gap due to the water level difference, and then flows through the interfiber gap by the pressure gradient. ,
In the microbial colony, the treated water is controlled to a predetermined range of oxidation-reduction potential by the oxidation-reduction potential adjusting means so that the ammonia-based nitrogen is less dissolved and the organic matter is dissolved well and a suitable anaerobic state is obtained. The nitrogen removal device using a string-like fiber aggregate, wherein the device is discharged from the filtering member in a state of being discharged and discharged to the outside of the treated water storage section by the treated water discharge means. 7. The nitrogen removing apparatus according to claim 5, wherein the oxidation-reduction potential of the treated water is controlled in a range of -120 mV to +50 mV. 8. The nitrogen removing apparatus according to claim 5, 6 or 7, wherein the concentration of the solid matter in the microbial colony is 3% by weight to 5% by weight.

Images