JP2011200829A - Raw water purifying method and apparatus of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a raw water purifying method and an apparatus therefor with a more compact structure so that the mechanism for supplying phosphoric acid or a phosphate, after it starts demonstrating sufficient ammonia nitrogen removal capacity in the zone where nitrobacteria acts, can be removed easily as a temporary device.SOLUTION: The raw water purifying method and apparatus include: a primary filter tank 2 comprising an iron removal zone Z1 carrying out iron removal treatment in the raw water using iron bacteria, and a nitrification zone Z2 carrying out ammonia nitrogen removal treatment in the raw water using nitrobacteria formed at the lower part of the iron removal zone Z1; and a secondary filter tank 3 carrying out manganese removal treatment in the raw water. A discharge port 10a is opened on the peripheral surface. Also, a supply nozzle 10 of phosphoric acid or phosphate solution in which the discharge port 10a is covered with a cylindrical elastic member 11 on which a cut-in 11a is formed, and a supply means 4 of the phosphoric acid and phosphate solution which supplies phosphoric acid or phosphate solution to the nozzle 10 are provided. The nozzle 10 is arranged at the nitrification zone Z2 of the primary filter tank 2.

Description

The present invention relates to a purification method and apparatus for raw water, and particularly for drinking iron, manganese, ammonia nitrogen (NH ₄ ⁺ -N), etc. contained in groundwater (hereinafter sometimes referred to as “raw water”). The present invention relates to a method for purifying raw water in which an unsuitable impurity is removed and its removal capability is improved by a simple method so as to treat efficiently.

Conventionally, there are chemical oxidation methods and bacterial methods as methods for removing impurities from groundwater containing impurities that are not suitable for drinking such as iron, manganese and ammoniacal nitrogen. This chemical oxidation method is a method of injecting chlorine and a flocculant into raw water, followed by a coagulation sedimentation treatment, followed by manganese sand filtration, and the other bacterial method is a filamentous form originally present in the soil near the raw water. Leptothrix sp., Toxothrix sp., Gallionella sp. And other iron-oxidizing bacteria (iron bacteria), manganese-oxidizing bacteria (manganese bacteria), and nitrifying bacteria (nitrifying bacteria) In this method, ammonia is oxidized and iron is captured in the form of hydroxide insolubilized on the bacterial surface.
In recent years, bacterial treatment facilities that can be automatically operated at a filtration rate of about 70 to 80 m / day or more have been proposed, mainly in water purification plants that use groundwater as raw water.

  By the way, the above-mentioned method is to remove impurities such as iron, manganese and ammonia nitrogen by a unified supply of dissolved oxygen in any facility. However, bacteria that act on individual substances have an optimal dissolved oxygen concentration, and in the case of the conventional method, the dissolved oxygen concentration cannot be adjusted so as to be optimal for individual bacteria. For example, in the case of the conventional method, dissolved oxygen is often supplied by a simple aeration method such as natural flow, and in that case, the optimal dissolved oxygen concentration range of iron bacteria is fully used. Since it is considerably lower than the optimum dissolved oxygen concentration, it takes a considerable number of days to exhibit stable manganese removal performance, although it is not particularly limited. For example, it takes 20 to 50 days, or manganese (Mn) There was a problem that it could hardly exert its effect on removal, and further, depending on water sources such as high concentration of iron (Fe) and high concentration of manganese (Mn), sufficient manganese removal performance could not be exhibited. .

In order to improve manganese removal performance, it is necessary to increase the dissolved oxygen concentration. In this case, if the adjustment of the unified bacterial growth environment is performed, the concentration will be considerably higher than the optimum dissolved oxygen range of iron bacteria. However, there is a problem that the iron removal performance is lowered.
Therefore, what can be processed by the conventional method is limited to a water source having a relatively low load of iron (Fe) and manganese (Mn), or limited to a case where the removal target substance is only iron. was there.

  Therefore, separating the iron / ammonia nitrogen removal part and the manganese removal part, each optimal dissolved oxygen concentration required by the bacteria group involved in the removal of iron / ammonia nitrogen and the bacteria removing manganese respectively. Therefore, it is possible to cope with high concentrations of iron, manganese, and ammonia nitrogen, and to improve the final treated water quality (see, for example, Patent Document 1).

However, at the beginning of water flow, the activity of the nitrification zone (nitrification bacteria growth zone) that should develop under the iron removal zone (iron bacteria growth zone) is insufficient and the removal rate of ammonia nitrogen does not proceed smoothly. There was an example. As a result of considering this cause, the possibility of the phosphorus content contained in the raw water was considered.
The groundwater contains a small amount of phosphorus compounds. This phosphorus compound plays a major role in the oxidation of ammoniacal nitrogen contained in the same groundwater.
In other words, if the phosphorus concentration in groundwater is sufficiently high in the iron removal by bacteria method, even if a considerable phosphorus compound is taken into the production zone of iron oxyhydroxide produced by the oxidation of Fe (II) by iron bacteria, A concentration at which sufficient nitrification occurs in the lower nitrification zone is reached, with the result that ammoniacal nitrogen is removed.

On the other hand, if the phosphorus compound concentration in the groundwater is low, or if the phosphorus compound consumption in the iron removal zone is significant, it will be understood that there are quite a few examples of such phosphorus deficiency. Is considered necessary.
Otherwise, another ammonia nitrogen removal process, such as the oxidation of ammonia nitrogen by a chlorinating agent, becomes necessary, which directly leads to an increase in the cost of building a water treatment facility.
As for the case where the removal of ammonia nitrogen in the iron bacteria treatment tank was sluggish, the phosphorus compound concentration just under the iron removal zone was measured just in case. As shown in Table 1, the phosphorus compound concentration was extremely low. Concentration (corresponding to a height of 60 cm from the filter layer surface).

This means that the activity of nitrifying bacteria is low or the number of bacteria remains low, and therefore ammonia nitrogen in raw water is not sufficiently removed, resulting in large fluctuations in chlorine demand. This means that it is difficult to manage the chlorine agent injection in the lower process than the iron removal process.
In the water purification treatment, variations in the chlorine demand due to such residual ammoniacal nitrogen are disliked.
For this reason, there is a concern that the iron removal processing system itself having such bad characteristics is not accepted.

  In order to cope with this problem, the raw water purification method previously proposed by the present inventors performs iron removal treatment in raw water using iron bacteria and manganese removal treatment in raw water using a manganese removal filter medium. In the raw water purification method, the iron removal zone for removing iron in the raw water using iron bacteria, the manganese removal zone for removing manganese in the raw water using the manganese removal filter medium after the iron removal treatment, and Phosphoric acid or phosphate is added to the nitrification zone between the two to improve the ability to remove ammoniacal nitrogen by nitrifying bacteria (see Patent Document 2).

  As a result, oxidation of ammonia nitrogen in the raw water by nitrifying bacteria (nitrification reaction) proceeds smoothly from the stage immediately after iron removal by iron bacteria, so even if the water source contains only a few phosphate ions, Ammonia nitrogen can be reliably removed, and system maintenance and management, such as management of the chlorinating rate, has become easier.

And in the actual apparatus using this purification method of raw water, as a mechanism for supplying phosphoric acid or phosphate, as shown in FIG. 7, the cross-sectional shape withstands the pressure and water flow of the filter medium and has low resistance. Is connected to the convex lens-type hollow tube 50 in a lattice pattern so that liquid (phosphoric acid or phosphate solution) can communicate with each other. The frame 51 is fixed to the primary filtration tank 2.
And, in several places of such a lattice-like hollow tube 50, there are provided injection ports to the filter medium of phosphoric acid or phosphate solution so as to prevent water or foreign matter from entering the tube from the outside. Linked with phosphate solution supply means (drug injection equipment) and diffused evenly to the zone where nitrifying bacteria act, smooth removal of ammonia nitrogen is achieved, and ammonia nitrogen removal performance is demonstrated. The operation start-up period can be shortened.

JP 2007-61809 A JP 2009-274020 A

By the way, the mechanism for supplying phosphoric acid or phosphate in an actual apparatus using the above raw water purification method is a large and complicated structure as shown in FIG. However, there was a problem that the cost of the entire equipment was soaring.
In addition, as a result of examination by subsequent experiments, it becomes clear that the supply of phosphoric acid or phosphate can provide a smooth removal effect of ammonia nitrogen only in a relatively short period at the start-up at the beginning of operation, After the nitrifying bacteria grew and activated and exhibited sufficient ammonia-ammonia capacity, it was found preferable to remove the phosphate or phosphate supply mechanism. Alternatively, the mechanism for supplying phosphate has a problem that the removal work cannot be easily performed because the structure has a large and complicated shape.

  In view of the problems of the above-described conventional raw water purification method and apparatus, the present invention provides a mechanism for supplying phosphoric acid or phosphate with sufficient ammonia-removing ability in a zone where nitrifying bacteria act. After having come to exhibit, it aims at providing the purification method of raw water and its device which were made into a more compact structure as a temporary device which can be removed easily.

  In order to achieve the above object, the raw water purification method of the present invention performs the iron removal treatment in the raw water with the use of iron bacteria, and after the removal of ammoniacal nitrogen in the raw water with the use of nitrifying bacteria, In the purification method of raw water that performs manganese removal treatment in water, a cylindrical elastic member having a discharge hole formed in the peripheral surface and a cut formed in the discharge hole in a nitrification zone that performs ammonia removal nitrogen treatment by nitrifying bacteria The phosphoric acid or phosphate solution supply nozzle covered with the above is positioned to supply phosphoric acid or phosphate to the nitrification zone.

  In addition, the raw water purification apparatus of the present invention used in the above method comprises a iron removal zone for performing iron removal treatment in raw water using iron bacteria, and a raw material using nitrifying bacteria formed under the iron removal zone. In the raw water purification apparatus comprising a primary filtration tank comprising a nitrification zone that performs deammonia nitrogen treatment in water, and a secondary filtration tank that performs manganese removal treatment in raw water, a discharge hole is opened on the peripheral surface, A phosphoric acid or phosphate solution supply nozzle configured to cover the discharge hole with a cylindrical elastic member having a cut, and a phosphoric acid or phosphate solution for supplying phosphoric acid or a phosphate solution to the nozzle And the nozzle is disposed in the nitrification zone of the primary filtration tank.

  In order to achieve the same object, the raw water purification method according to the second aspect of the present invention uses iron bacteria to remove iron from raw water and also uses nitrifying bacteria to remove ammonia nitrogen in raw water. Then, in the purification method of the raw water that performs the manganese removal treatment in the raw water, a filter medium combined with phosphate ions is disposed in the nitrification zone in which the denitrification nitrogen treatment by nitrifying bacteria is performed, and the ions contained in the raw water It is characterized in that phosphate ions are released into the nitrification zone by the ion exchange action.

  In addition, the raw water purification apparatus of the present invention used in the above method comprises a iron removal zone for performing iron removal treatment in raw water using iron bacteria, and a raw material using nitrifying bacteria formed under the iron removal zone. In a purification system for raw water that has a primary filtration tank consisting of a nitrification zone that performs denitrification treatment in water and a secondary filtration tank that carries out manganese removal treatment in raw water, phosphate ions are bound to the nitrification zone. It is characterized by disposing a filter medium.

  According to the raw water purification method and apparatus therefor according to the first aspect of the present invention, a cylindrical shape in which a discharge hole is formed in the peripheral surface and a cut is formed in the discharge hole in the nitrification zone for performing the ammonia-removing nitrogen treatment by nitrifying bacteria. The supply nozzle of the phosphoric acid or phosphate solution covered with the elastic member is positioned so as to supply phosphoric acid or phosphate to the nitrification zone. The supply nozzle can be easily inserted and removed from the zone, and after the action of phosphoric acid or phosphate, the nitrifying bacteria grow and become active, so that sufficient ammonia-removing nitrogen ability is exhibited. Can easily remove the phosphate or phosphate supply mechanism.

Further, according to the raw water purification method and apparatus therefor according to the second aspect of the present invention, a filter medium combined with phosphate ions is disposed in a nitrification zone for performing denitrification nitrogen treatment with nitrifying bacteria, and is contained in the raw water. By allowing phosphate ions to be released into the nitrification zone by ion exchange with ions, when the raw water is passed through a filter medium to which phosphate ions are bound, the bound phosphate ions are contained in the raw water. The nitrifying bacteria are gradually released into the raw water by the exchange reaction with the generated ions, and the nitrifying bacteria are proliferated and activated, thereby exhibiting sufficient ammonia-removing ability of nitrogen.
When almost complete nitrification of ammonia nitrogen was achieved, all phosphate ions were released from the filter medium combined with phosphate ions. After that, it can be used as a normal filter medium as it is. it can.

It is the schematic which shows the 1st Example of the purification method of the raw | natural water of this invention, and its apparatus. The nozzle for the supply of the phosphoric acid or phosphate solution used for the method and its apparatus is shown, (a) is a partially cutaway plan view, (b) is an XX cross-sectional view of (a). . It is a partially cutaway perspective view showing an installation example of the nozzle. It is a graph which shows the time-dependent change of ammoniacal nitrogen at the time of adding phosphoric acid or a phosphate directly to raw | natural water. It is a graph which shows the time-dependent change of ammonia nitrogen, (a) is a case where phosphoric acid or a phosphate is not added, (b) is a case where phosphoric acid or a phosphate is added. It is the schematic which shows 2nd Example of the purification method of the raw | natural water of this invention, and its apparatus. The supply mechanism of the phosphoric acid or phosphate used for the purification method of the conventional raw water is shown.

  Hereinafter, embodiments of a purification method and apparatus for raw water according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the raw water purification method and apparatus according to the present invention.
This raw water purification apparatus 1A includes an iron-removing zone Z1 for removing iron in raw water using iron bacteria, and a denitrifying nitrogen in the raw water using nitrifying bacteria formed under the iron-removing zone Z1. A primary filtration tank 2 comprising a nitrification zone Z2 for treatment and a secondary filtration tank 3 for carrying out manganese removal treatment in the raw water, opening a discharge hole 10a on the peripheral surface, and cutting the discharge hole 10a into a cut 11a Phosphoric acid or phosphate solution supply nozzle 10 covered with the formed cylindrical elastic member 11, and phosphoric acid or phosphate solution supply means for supplying phosphoric acid or phosphate solution to the nozzle 10 4 and the nozzle 10 is arranged in the nitrification zone Z2 of the primary filtration tank 2.

Specifically, as shown in FIG. 1, from a tubular casing 20 via a raw water supply pump P1 and a raw water supply pipe 5 from a tank T1 directly pumped from a groundwater source or temporarily stored by pumping up groundwater. The raw water (ground water) is supplied to the water supply port 2A provided at the upper part of the primary filtration tank 2.
A water supply port 3 </ b> A provided in the upper part of the secondary filtration tank 3 is connected via a pipe 6 from a drain port 2 </ b> B provided in the lower part of the primary filtration tank 2.
Moreover, dissolved oxygen DO1 and DO2 are supplied to the raw water supply pipe 5 and the pipe 6 by appropriate means.
In this case, an aeration tank (not shown) may be provided in the middle of the pipe 6 and the treated water may be supplied to the secondary filtration tank 3 after supplying the secondary dissolved oxygen.
The specific example shown in FIG. 1 is used, for example, for supplying industrial water used for manufacturing industrial products.

  The primary filtration tank 2 is filled with an iron bacteria filter material 21 (iron removal zone Z1) made of anthracite or the like inside, and below that is used for raw water using nitrifying bacteria made of a sand layer supported by a support layer 23. The nitrifying bacteria filter medium 22 (nitrification zone Z2) for performing the ammonia-removing nitrogen treatment is filled.

  In the nitrification zone Z2 of the primary filtration tank 2, a phosphoric acid or phosphate solution supply nozzle 10 connected to the phosphoric acid or phosphate solution supply means 4 is disposed.

Although the material of the nozzle 10 is not particularly limited, in this embodiment, stainless steel made of SUS316 or the like having strength that does not deform when inserting and removing from the filter layer and high corrosion resistance is used. .
And as shown in FIG. 2, the discharge hole 10a is opened in the surrounding surface of the front-end | tip part 10b vicinity.
The number of the discharge holes 10a and the opening positions are not particularly limited, but the openings are opened at three positions above and below by shifting the phase by 120 °.
The discharge hole 10a is covered with a cylindrical elastic member 11, and prevents entry of liquid or foreign matter from the outside into the nozzle 10.

The material of the elastic member 11 is not particularly limited, but in this embodiment, an elastic organic polymer film is used.
The elastic member 11 forms a small notch 11a at a position (a shifted position) that does not coincide with the discharge hole 10a when attached.
The number of the cuts 11a and the opening positions are not particularly limited, but the openings are shifted by 120 ° in the upper and lower three positions as in the case of the discharge holes 10a.

  The elastic member 11 is brought into close contact with the opening position of the discharge hole 10 a and fixed up and down with the tube band 12. At this time, by forming a groove-shaped step portion having a diameter slightly smaller than the outer diameter of the nozzle 10 above and below the opening position of the discharge hole 10 a of the nozzle 10, the tube band 12 protrudes greatly from the outer peripheral surface of the nozzle 10. Therefore, it is possible to prevent the elastic member 11 from being displaced or dropped from the nozzle 10 during insertion into and removal from the filter layer.

When supplying the phosphoric acid or phosphate solution, the phosphoric acid or phosphate solution is discharged from the discharge hole 10a of the nozzle 10, and the peripheral surface of the nozzle 10 and the elastic member 11 made of an organic polymer film that is in close contact with the elastic member 11 It will be in the state filled between.
In this case, the cut 11a is slightly opened due to the elasticity of the organic polymer film, and the phosphoric acid or phosphate solution is released to the outside (that is, toward the nitrifying bacteria filter medium 22). Is done.
When the supply of the phosphoric acid or phosphate solution is stopped, the organic polymer film is restored in shape so as to block the notch 11a, which is the outlet of the liquid, due to its elasticity, and intrusion of liquid or foreign matter from the outside. It works to prevent.

Further, the tip portion 10b of the nozzle 10 has a sharp pointed shape so that it can be easily inserted into and extracted from the filter layer.
The other end 10c of the nozzle 10 is formed with a male screw on the outer peripheral surface or a male screw on the inner peripheral surface, and is connected to a pipe 13 made of a stainless steel pipe such as SUS316.

The phosphoric acid or phosphate solution supply means 4 includes a chemical solution tank 40 that stores phosphoric acid or a phosphate solution, a chemical solution supply pump 41, and a chemical solution supply pipe 42 that connects the chemical solution supply pump 41 and the pipe 13.
The chemical solution supply pipe 42 may be a steel hose or a blade hose made of a flexible material.
Here, the amount of phosphoric acid or phosphate added to the raw water, as will be described later, increases the number of nitrifying bacteria and manganese bacteria, and is a very small amount, to the extent that satisfies the conditions for increasing its activity, Although it does not specifically limit, It sets so that it may become about 0.1 mg / L with respect to raw | natural water, for example. Thereby, it is hardly detected as phosphate ions in the final treated water, and the quality of the purified water becomes safe.

Then, the phosphoric acid or phosphate solution of the phosphoric acid or phosphate solution supply means 4 is supplied from the nozzle 10 to the nitrification zone Z2 formed of a sand layer formed at the lower position of the iron removal zone Z1.
As a result, the nitrifying bacteria can be grown and activated in the nitrifying zone Z2, the ammonia nitrogen removal ability by the nitrifying bacteria can be improved, and there is no need to provide a dedicated nitrifying tank.

  The secondary filtration tank 3 that performs manganese removal treatment in the raw water is a primary filtration tank that has been subjected to iron removal and ammonia-removing nitrogen treatment in the primary filtration tank 2 that is supplied from a water supply port 3 </ b> A provided in the upper part of the cylindrical housing 30. This is a process for removing manganese from the treated water. The required manganese bacteria filter material 31 is filled inside, and the final treated water subjected to the manganese bacteria filtration treatment is drained to the lower position and supplied to the final treated water tank T. For this purpose, a water distribution port 3B to which a final treated water distribution pipe 7 is connected is provided.

Further, by setting the injection amount of phosphoric acid or phosphate from the nozzle 10 so that a slight amount of phosphoric acid or phosphate remains in front of the secondary filtration tank 3, the bacteria of the manganese bacteria It is possible to increase the number and increase the activity, and as a result, the concentration of dissolved oxygen required to exhibit the manganese removal performance can be greatly reduced.
This eliminates the need for high-concentration oxygen gas generators such as PSA, which were necessary when phosphoric acid or phosphate was not added, and a device for efficiently dissolving oxygen gas in water. Since the target dissolved oxygen concentration can be achieved with a simple aeration mechanism, the initial cost can be greatly reduced.
By adding phosphoric acid or phosphate, the adaptive dissolved oxygen concentration range of manganese bacteria is expanded, so that it is easy to maintain and maintain it, which is preferable in practice.

  Moreover, when the residue of the phosphoric acid injected from the nozzle 10 or a phosphate cannot be anticipated, phosphoric acid or a phosphate can also be added in the front position of the secondary filtration tank 3. FIG.

  Manganese bacteria filtering material 31 is used for the manganese removal treatment, and water containing chlorinating agent may be used in water purification equipment and the like used for water supply (the water law states that residual chlorine exists). It is also possible to employ a manganese removal treatment system that removes manganese in raw water using a general manganese removal filter medium.

When the supply nozzle 10 for the phosphoric acid or phosphate solution is installed in the implementation facility, the nozzle 10 shown in FIG. 1 is used as a fixed frame 14 that also serves as a pipe as shown in FIG. It is preferable to install a plurality of nozzle groups set at regular intervals in a grid pattern.
The length from the fixed frame 14 to the nozzle 10 is set so that the nozzle 10 moves to the nitrification zone Z2 when the fixed frame 14 is positioned on the iron bacteria filter medium 21 made of anthracite or the like that becomes the surface of the iron removal zone Z1. By setting the length to be located, each nozzle 10 reaches a predetermined position in the nitrification zone Z2 by inserting the nozzle group into the filter layer until the fixed frame 14 is located on the iron bacteria filter medium 21, and the nitrification zone Z2 The phosphoric acid or phosphate solution can be distributed throughout.

In addition, since the nozzle 10 or a group of nozzles 10 in which a plurality of nozzles 10 are set can be easily inserted into and removed from the filter layer, nitrifying bacteria can be grown and activated in the primary filtration tank 2, and ammonia nitrogen can be almost completely removed. It can be easily removed after nitrification is achieved.
And since the stainless steel material with high corrosion resistance is used for the nozzle 10 and the piping 13, after removing, it can also be reused in another raw water processing system.

[Experimental Example 1]
As shown in FIG. 4, when the raw water is supplemented with phosphoric acid or a phosphate solution, most of the administered phosphoric acid or phosphate solution is consumed in the iron removal zone, but the rest is It passed through the iron removal zone Z1 and reached the nitrification zone Z2, and it was confirmed that the oxidation (nitrification reaction) of ammoniacal nitrogen in the raw water by nitrifying bacteria proceeded.
However, as shown in the raw water graph of FIG. 4, the progress of nitrification is extremely slow, and the removal rate of ammonia nitrogen by nitrification is not so high.
In conclusion, the method of injecting the phosphoric acid or phosphate solution before passing through the iron removal zone Z1 has a high wasteful consumption rate of the phosphoric acid or phosphate solution, and is an efficient means. I can't say that.
Therefore, as shown in the present invention, the injection position of the phosphoric acid or phosphate solution is preferably set in the filter layer (nitrification zone Z2) at the position where iron removal is almost completed in the iron bacteria filtration step, This can prevent ineffective consumption of the phosphoric acid or phosphate solution by the iron oxide produced by the action of iron bacteria.
By injecting into the middle part of the filter layer (upstream of the nitrification zone Z2) where iron removal has been almost completed, it is possible to prepare an environment where the phosphate or phosphate solution is consumed only for the growth of nitrifying bacteria (nitrifying bacteria). The filtration layer after the injection point of phosphoric acid or phosphate solution can be a nitrification zone Z2 specialized for ammoniacal nitrogen removal.

[Experiment 2]
When the operation of the iron bacteria filtration tank was started, a comparative experiment was performed depending on whether or not phosphoric acid or a phosphate solution was added to the middle part of the filter layer.
When the phosphoric acid or phosphate solution was not added, an operation period of about 40 days was required until ammonia nitrogen in the raw water was almost completely removed, as shown in FIG. 5 (a). However, when phosphoric acid or a phosphate solution was added, it could be achieved in about 20 days as shown in FIG.
Therefore, it is considered that the added phosphorus content increased the ability of nitrifying bacteria to grow, leading to an improvement in the nitrifying ability of ammoniacal nitrogen.

FIG. 6 shows a second embodiment of the raw water purification method and apparatus according to the present invention.
This raw water purification apparatus 1B includes an iron-removing zone Z1 for performing iron-removing treatment in raw water using iron bacteria, and a denitrifying nitrogen in the raw water using nitrifying bacteria formed below the iron-removing zone Z1. A primary filtration tank 2 composed of a nitrification zone Z2 for treatment and a secondary filtration tank 3 for manganese removal treatment in raw water are provided, and a filter medium 8 combined with phosphate ions is disposed in the nitrification zone Z2. Phosphate ions bonded to the filter medium 8 are discharged into the nitrification zone Z2 by an ion exchange action with ions contained in the raw water.

Specifically, as in the first embodiment, as shown in FIG. 6, either directly from the groundwater source or from the tank T1 that is temporarily stored by pumping up the groundwater, through the raw water supply pump P1 and the raw water supply pipe 5, Raw water (ground water) is supplied to a water supply port 2 </ b> A provided in the upper part of the primary filtration tank 2 composed of a cylindrical casing 20.
A water supply port 3 </ b> A provided in the upper part of the secondary filtration tank 3 is connected via a pipe 6 from a drain port 2 </ b> B provided in the lower part of the primary filtration tank 2.

  The primary filtration tank 2 is filled with an iron bacteria filter material 21 (iron removal zone Z1) made of anthracite or the like inside, and below that is used for raw water using nitrifying bacteria made of a sand layer supported by a support layer 23. The nitrifying bacteria filter medium 22 (nitrification zone Z2) for performing the ammonia-removing nitrogen treatment is filled.

  In the nitrification zone Z2 of the primary filtration tank 2, a filter medium 8 combined with phosphate ions is arranged. Specifically, the filter medium 8 is mixed with the sand layer upstream of the nitrifying bacteria filter medium 22, or the upstream sand layer is replaced with the filter medium 8.

The filter medium 8 is obtained by sufficiently binding phosphate ions in advance to a support in which an iron-based compound having anion exchange ability is supported on a support such as silica sand. Separately, a filter medium in which a hydroxide ion supplier is supported on a support such as silica sand is mixed, and the amount of phosphate ions released from the iron-based compound is controlled by the ratio. .
When this is used as the filter medium 8 and raw water is passed through, the bound phosphate ions are gradually released into the raw water by exchange reaction with other ions in the raw water, and the phosphoric acid of the first embodiment. Alternatively, the same effect as the supply of the phosphoric acid or the phosphate solution from the phosphate solution supply nozzle 10 can be obtained.
Further, as shown in FIG. 6, the filter medium 8 is disposed (filled) so as to be located upstream of the nitrification zone Z2, so that phosphate ions are spread throughout the nitrification zone Z2, and nitrifying bacteria in the nitrification zone Z2 are dispersed. Proliferation and activation can be achieved, the ability to remove ammoniacal nitrogen by nitrifying bacteria can be improved, and there is no need to provide a dedicated nitrification tank.

By the time when almost complete nitrification of ammonia nitrogen in the primary filtration tank 2 is achieved by the effect of phosphate ions, all phosphate ions are released from the filter medium 8, and thereafter, the normal filtration is performed as usual. It can be used as a filter medium.
By using this method and apparatus, it is possible to save the trouble of installing and removing the temporary device of the nozzle group including the nozzle 10 for supplying the phosphoric acid or phosphate solution as in the first embodiment. It is a feature.

  The other configuration and operation of the present embodiment are the same as those of the first embodiment.

  As mentioned above, although the purification method and the apparatus of the raw water of this invention were demonstrated based on the several Example, this invention is not limited to the structure described in the said Example, A phosphoric acid or phosphate solution The configuration can be changed as appropriate without departing from the spirit of the present invention, for example, by using a combination of a supply nozzle and a filter medium combined with phosphate ions.

  The purification method and apparatus for raw water according to the present invention provides a mechanism for supplying phosphoric acid or phosphate after exhibiting sufficient nitrogen-removing ability in a zone where nitrifying bacteria act. Since it has a characteristic that it can be easily removed, it can be used widely and suitably as a purification system for raw water such as ground water that is inexpensive and easy to manage.

1A Purification device 1B Purification device 2 Primary filtration tank 3 Secondary filtration tank 4 Means for supplying phosphoric acid or phosphate solution 5 Raw water supply pipe 6 Pipe 7 Final treated water distribution pipe 8 Filter medium 10 Supply of phosphoric acid or phosphate solution Nozzle 10a Discharge hole 11 Elastic member 11a Cut 14 Fixed frame 21 Filter medium 22 Filter medium 31 Manganese bacteria filter medium Z1 Iron removal zone Z2 Nitrification zone

Claims (4)

  In the purification method of raw water, which uses iron bacteria to remove iron in raw water, and after nitrifying bacteria to remove ammoniacal nitrogen in raw water, remove manganese in raw water, In the nitrification zone where the ammonia-removing nitrogen treatment is performed, a discharge nozzle is opened on the peripheral surface, and a supply nozzle for a phosphoric acid or phosphate solution, which is covered with a cylindrical elastic member in which the discharge hole is formed, is positioned. A method for purifying raw water, wherein phosphoric acid or phosphate is supplied to the nitrification zone.   Primary filtration comprising an iron removal zone for removing iron in raw water using iron bacteria and a nitrification zone for removing ammonia nitrogen in raw water using nitrifying bacteria formed below the iron removal zone In a raw water purification apparatus comprising a tank and a secondary filtration tank for removing manganese in the raw water, a discharge hole is opened in the peripheral surface, and the discharge hole is covered with a cylindrical elastic member having a cut. A phosphoric acid or phosphate solution supply nozzle, and a phosphoric acid or phosphate solution supply means for supplying phosphoric acid or a phosphate solution to the nozzle, wherein the nozzle is a nitrification zone of a primary filtration tank An apparatus for purifying raw water.   In the purification method of raw water, which uses iron bacteria to remove iron in raw water, and after nitrifying bacteria to remove ammoniacal nitrogen in raw water, remove manganese in raw water, A filter medium combined with phosphate ions is installed in the nitrification zone where the ammonia-removing nitrogen treatment is performed, and phosphate ions are released into the nitrification zone by ion exchange with ions contained in the raw water. A method for purifying raw water.   Primary filtration comprising an iron removal zone for removing iron in raw water using iron bacteria and a nitrification zone for removing ammonia nitrogen in raw water using nitrifying bacteria formed below the iron removal zone A raw water purification device comprising a tank and a secondary filtration tank for removing manganese in the raw water, wherein the filter medium combined with phosphate ions is disposed in the nitrification zone. .

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