JP2002336605A - Water treatment system and floc forming pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system, by which water to be treated is purified without using an aluminum based flocculant, the whole system is prevented from being large scaled, the time necessary for purifying is reduced and the purifying performance for the water to be treated is improved. SOLUTION: The water treatment system 1 is provided with a water receiving well 2 into which the water to be treated flows, a settling tank 6 in which floc 20 in the water to be treated is settled and a floc forming pipe 9 for connecting between the water receiving well 2 and the settling tank 6. The settling tank 6 is connected to a filtration tank 7 through a settlement water conduit 17 and the filtration tank 7 is connected to a water discharge pipe 18 to which a sterilization pipe 19 is attached. The floc forming pipe 9 has a flocculant mixing zone 21 where a flocculant injection pipe 8 for injecting polysilica iron 16 is injected to the water to be treated is attached, a floe forming zone 22 connected to the flocculant mixing zone 21 and for forming the floc 20 and a floc growing zone 23 connected to the floc forming zone 22 and for growing the floc 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment system for purifying water to be treated by coagulating and sedimenting suspended substances in the water to be treated.

[0002]

2. Description of the Related Art Conventionally, a rapid filtration method has been employed as a water treatment system for purifying treated water such as raw water from a river into tap water. This rapid filtration method includes a coagulation sedimentation step of coagulating and sedimenting the turbidity and bacteria in order to remove turbid matter and bacteria in the water to be treated, a filtration step of filtering the water to be treated through the coagulation and sedimentation step, It comprises a disinfection step of disinfecting the water to be treated that has passed through the process.

[0003] Generally, in the coagulation sedimentation step of a water treatment system employing a rapid filtration method, an aluminum-based coagulant such as aluminum sulfate or polyaluminum chloride (PAC) is used.

FIG. 5 is a configuration diagram showing a conventional water treatment system employing a rapid filtration system.

The water treatment system shown in FIG. 5 includes a landing well 2 into which water to be treated flows, and a mixing pond 3 connected to the landing well 2 via a communication pipe 2a and into which water to be treated from the landing well 2 flows. ,
The mixing pond 3 is connected to the downstream side of the mixing pond 3 through the raw water drain 4.
And a floc forming pond 5 into which the water to be treated flows. A sedimentation basin 6 is connected to the downstream side of the floc formation basin 5, and an inclined plate device 6 a for promoting floc sedimentation is provided in the sedimentation basin 6. Communication pipe 2a
Is provided with a coagulant injection tube 8. A filtration basin 7 is connected to the downstream side of the sedimentation basin 6 via a sewer culvert 17, and a filter sand 7 a and a lower water collecting device 7 are provided in the filtration basin 7.
b is installed. A discharge pipe 18 is provided downstream of the filtration pond 7.
Is connected to the discharge pipe 18, and a disinfection pipe 19 for injecting a disinfectant into the water to be treated is attached to the discharge pipe 18.

The flocculation and sedimentation step is constituted by the landing well 2, the communication pipe 2a, the coagulant injection pipe 8, the mixing pond 3, the raw culvert 4, the floc forming pond 5, and the sedimentation pond 6. Yes,
The filtration step is constituted by the filtration pond 7 and the discharge pipe 18
And the disinfection tube 19 constitute a disinfection process.

The water to be treated, which has flowed into the landing well 2, is injected with the aluminum-based coagulant 15 through the coagulant injection pipe 8.
It flows into the mixing pond 3. In the mixing pond 3, the water to be treated is rapidly stirred by the flash mixer 10 installed in the mixing pond 3, and fine colloid particles composed of turbid components and bacteria floating in the water to be treated aggregate to form flocs (particle clumps). ) 20
To form Note that the flash mixer 10 is a motor 10
Driven by a.

The water to be treated in the mixing pond 3 flows into the floc formation pond 5 via the raw water culvert 4 together with the floc 20. In the floc formation pond 5, the water to be treated is stirred by the flocculator 11 installed in the floc formation pond 5, and the floc 20 contained in the water to be treated grows slowly and largely.

The water to be treated in the floc forming pond 5 flows into the sedimentation pond 6 together with the grown floc 20. Settling basin 6
Then, the flocks 20 settle down due to gravity. The water to be treated after the floc 20 has settled in the sedimentation basin 6 has a turbidity of about 1 degree or less, but the treated water still contains fine suspended substances. In addition, the sedimentation of the floc 20 is promoted by the inclined plate device 6a.

The water to be treated in the sedimentation basin 6 is sent to the filtration basin 7 through the sedimentation culvert 17, and the fine sand contained in the water to be treated is filtered by the filter sand 7a in the filtration basin 7 and the lower water collecting device 7b. Is removed. Thereafter, the water to be treated flows out of the filtration pond 7 to the discharge pipe 18, and the water to be treated flowing through the discharge pipe 18 is disinfected by injecting a disinfectant from the disinfecting pipe 19. In this way, the water to be treated is purified and supplied to clear and safe tap water.

[0011]

As described above, water to be treated such as raw water is purified into clear and safe tap water by the water treatment system 1 using the aluminum-based coagulant 15.

However, sludge containing a large amount of aluminum has a reduced sedimentation and condensing property when settling in the water to be treated and a dewatering property when dewatering from the water to be treated.

The water treatment system 1 using the aluminum-based flocculant 15 includes large facilities such as a flocculant injection pipe 8, a mixing pond 3, a raw culvert 4, and a floc forming pond 5, in addition to the landing well 2. Since it is necessary, it is difficult to secure an installation site for the water treatment system 1, and a long time is required for a series of treatment steps.

When the aluminum-based flocculant 15 is used, it is difficult to completely remove the pathogens of Cryptosporidium from the water to be treated.

Further, it is not preferable to accumulate a large amount of aluminum contained in the aluminum-based coagulant 15 in the human body and the environment.

The present invention has been made in view of the above points, and can purify water to be treated without using an aluminum-based flocculant. It is an object of the present invention to provide a water treatment system capable of shortening the time and improving the purification performance of the water to be treated.

[0017]

SUMMARY OF THE INVENTION The present invention relates to a water treatment system for injecting a coagulant into water to be treated and subjecting the water into which the coagulant has been injected to settling treatment. A well, a sedimentation basin for sedimenting the water to be treated mixed with the coagulant, and a floc forming pipe connecting between the landing well and the sedimentation pond, the floc forming pipe is configured to transfer the flocculant into the water to be treated. A water treatment system comprising: a flocculant mixing region to be injected; a floc forming region for forming flocs in water to be treated by the flocculant; and a floc growth region for growing flocs.

According to the present invention, the landing well into which the water to be treated flows and the sedimentation basin in which the flocs in the water to be treated are settled are connected by a floc forming pipe. It has a simple structure consisting of a flocculant-mixed region injected into water, a floc-forming region in which flocs are formed from colloid particles in the water to be treated, and a floc growth region in which the formed flocs grow. In addition to preventing an increase in size, it is possible to shorten the time for purifying the water to be treated.

Preferably, the diameter of the floc forming tube is increased from the flocculant mixing region to the floc growth region.

[0020] Preferably, the floc forming pipe is provided with one or more baffles for inhibiting the flow of the water to be treated in the floc forming pipe.

Preferably, the coagulant injected into the water to be treated in the coagulant mixing region of the floc forming tube is a silica-based iron salt coagulant.

The present invention provides a floc forming pipe for forming flocs in water to be treated, a flocculant-mixing region for injecting a flocculant into the water to be treated, and a floc forming region for forming flocs in the water to be treated by the flocculant. And a flock growth region for growing flock.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention. Here, FIG. 1 is a configuration diagram showing a water treatment system having a coagulation settling process, a filtration process, and a disinfection process, and FIG. 2 is a configuration diagram showing a floc forming tube used in the coagulation settling process of the water treatment system. .

In FIG. 1, a water treatment system 1 according to the present invention comprises a landing well 2 into which water to be treated containing colloidal particles such as turbid matter and bacteria flows, and a sedimentation pond 6 for sedimenting flocs 20 in the water to be treated. And a floc forming pipe 9 connecting between the landing well 2 and the sedimentation basin 6.

Downstream of the sedimentation basin 6, a filtration basin 7 is connected via a sewer culvert 17.
A filter sand 7a for removing fine suspended substances contained in the water to be treated, and a lower water collecting device 7b for collecting the water to be treated and assisting the passage of the water to be treated through the sand 7a are provided. I have.

A discharge pipe 18 is connected to the downstream side of the filtration pond 7. The discharge pipe 18 is provided with a disinfecting pipe 19 for injecting a disinfectant into water to be treated flowing through the discharge pipe 18.

As shown in FIGS. 1 and 2, the floc forming tube 9 is made of polysilica iron 16 which is a silica-based iron salt coagulant.
Mixing area 21 provided with a coagulant injection pipe 8 for injecting the water into the water to be treated, and a floc forming area connected to the coagulant mixing area 21 and forming flocs 20 from colloid particles in the water to be treated by the polysilica iron 16. 22 and a floc growth region 23 connected to the floc formation region 22 for growing the floc 20.

The pipe diameter of the floc forming pipe 9 in the flocculant mixing area 21 is smaller than the pipe diameter of the floc forming pipe 9 in the floc growing area 23, and the pipe diameter of the floc forming pipe 9 in the floc forming area 22 is upstream. From the side to the downstream side.

Further, in the flocculant-mixing region 21 of the floc-forming tube 9, downstream of the flocculant-injecting tube 8 and at the center of the floc-forming tube 9 in the radial direction of the pipe, a bowl-shaped first baffle is provided. A plate 12a is provided. Further, a second baffle plate 12b composed of a plurality of disks having different diameters is provided in an intermediate portion of the floc formation region 22. further,
A third baffle plate 12c is provided downstream of the second baffle plate 12b in the flock formation region 22, and a fourth baffle plate 12d is provided in the flock growth region 23. Each of the third baffle plate 12c and the fourth baffle plate 12d is composed of a plurality of disks having different diameters, similarly to the second baffle plate 12b. The first baffle 12a, the second baffle 12b,
Each of the third baffle plate 12c and the fourth baffle plate 12d is provided at right angles to the flow of the water to be treated, and obstructs the flow of the water to be treated in the floc forming pipe 9.

The water landing well 2, the flocculant injection pipe 8, the floc forming pipe 9, and the sedimentation basin 6 constitute a coagulation and sedimentation step, the filtration pond 7 constitutes a filtration step, and the discharge pipe 1
8 and the disinfection tube 19 constitute a disinfection process.

The polysilica iron (PSI) 16 is composed of water glass and an iron salt. More specifically, diiron chloride (iron salt) is added to polymerized silicic acid (water glass) polymerized and stabilized in an acidic region. Is the one with Here, the molecular weight of the polysilica iron 16 is 200,000 to 500,000.

Next, the operation of the present embodiment having such a configuration will be described.

The water to be treated such as raw water supplied to the water treatment system 1 first flows into the landing well 2, and the water flowing into the landing well 2 flows into the floc forming pipe 9. At this time, the polysilica iron 16 is injected from the flocculant injection pipe 8 into the water to be treated flowing in the floc forming pipe 9. When the polysilica iron 16 is injected into the water to be treated, the colloid particles in the water to be treated aggregate, and the flocs 20 are formed and grown. Thereafter, the water to be treated is sent to the sedimentation basin 6 together with the flocs 20.

In the sedimentation basin 6, the flocs 20 in the water to be treated settle down by gravity and settle at the lower part of the sedimentation basin 6. In this way, the colloid particles in the water to be treated become flocs 20 and are subjected to the precipitation treatment, and the turbidity of the water to be treated after the precipitation treatment becomes approximately 1 degree or less (aggregation precipitation step).

However, the treated water subjected to the sedimentation treatment in the sedimentation basin 6 still contains fine suspended substances. Then, the water to be treated, in which the colloid particles have been subjected to the sedimentation treatment in the coagulation sedimentation step, is sent from the sedimentation basin 6 to the filtration basin 7 through the sedimentation culvert 17, and is filtered by the filter sand 7a and the lower water collecting device 7b in the filtration basin 7. Fine suspended substances contained in the water to be treated are removed (filtration step). Then, the water to be treated after the filtration step further flows out from the filtration pond 7 to the discharge pipe 18. The water to be treated flowing through the discharge pipe 18 is disinfected by injecting a disinfectant from the disinfection pipe 19 (disinfection step). In this way, the water to be treated is purified and supplied to clear and safe tap water. In addition, the water to be treated flowing in the system of the water treatment system 1 is flowed using the potential energy of the water to be treated in the landing well 2.

Next, the injection of the polysilica iron 16 into the water to be treated and the formation and growth of the flocs 20 in the floc forming tube 9 will be described in detail with reference to FIG.

When the water to be treated flows in the floc forming pipe 9 between the landing well 2 and the sedimentation basin 6, the water to be treated flows into the flocculant mixing area 21, the floc forming area 22,
And sequentially pass through the floc growth region 23.

First, polysilica iron 16 is injected from the flocculant injection pipe 8 into the flocculant mixing area 21 with respect to the water to be treated flowing in the floc forming pipe 9. As a result, colloidal particles composed of turbid components and bacteria floating in the water to be treated aggregate. Then, the water to be treated mixed with the poly-iron is sent from the flocculant mixing area 21 to the floc forming area 22. At this time, the water to be treated is a bowl-shaped first baffle plate 12.
Collide with a. Thereby, the polysilica iron 16 injected into the water to be treated diffuses widely into the water to be treated, and the polysilica iron 16 and the water to be treated are mixed. Therefore, aggregation of the colloid particles in the water to be treated is promoted.

By increasing the flow velocity of the water to be treated flowing through the coagulant mixing area 21 to increase the collision of the water to be treated with the first baffle plate 12a, the polysilica iron 16
And the water to be treated are promoted. As described above, in order to increase the flow rate of the water to be treated flowing through the flocculant-mixed region 21, it is desirable that the pipe diameter of the floc forming pipe 9 in the flocculant-mixed region 21 be small.

The water to be treated flowing through the floc formation region 22 collides with the second baffle plate 12b and the third baffle plate 12c and is sent to the floc growth region 23. At this time,
The water to be treated includes the second baffle plate 12b and the third baffle plate 12c
The colloid particles in the water to be treated aggregate with each other and gradually form a large floc 20 because the particles collide with each other and are stirred by bypass.

As will be described later, the floc growth region 23
It is desirable that the flow rate of the water to be treated sent to the water be relatively low. For this reason, the size of the pipe diameter of the floc forming pipe 9 in the floc forming area 22 is gradually increased from the upstream side to the downstream side, and the flow rate of the water to be treated is gradually reduced.

The water to be treated flowing through the floc growth region 23 collides with the fourth baffle plate 12d and is sent to the subsequent settling basin 6. The water to be treated flowing in the floc growth region 23 collides with the fourth baffle plate 12 d and is detoured and agitated, so that the floc 20 formed in the floc formation region 22 further grows in the floc growth region 23. As a result, flocs 20 having a density and a size that easily settle in the sedimentation basin 6 are obtained. At this time, in order to grow the floc 20,
It is desirable that the flow rate of the to-be-processed water in the floc growth region 23 be reduced and the floc 20 be grown for a sufficient time. Therefore, the size of the pipe diameter of the floc formation pipe 9 in the floc growth area 23 is larger than the pipe diameter of the floc formation pipe 9 in the flocculant-mixed area 21 and the floc formation area 22. The flow rate of the treated water is lower than the flow rate of the treated water in the flocculant mixing region 21 and the floc forming region 22.

As described above, the water to be treated is sent from the landing well 2 to the sedimentation basin 6 through the floc forming pipe 9.
During this time, the water to be treated flowing in the floc forming pipe 9 repeatedly collides with the plurality of baffles and diffuses and detours sufficiently, so that the flocs 20 are sufficiently formed and grown.
Further, the water to be treated flowing in the floc forming pipe 9 is sufficiently bypassed by the baffle plate, so that no short-circuit flow is generated. Further, since the water to be treated flows in the floc forming pipe 9 having a simple structure in a short time, the coagulation and sedimentation step can be shortened, and the purification time of the water to be treated by the water treatment system 1 can be reduced. Can be shortened.

The water treatment system 1 uses the floc forming pipe 9 having a simple structure, and does not require the mixing pond 3 or the floc forming pond 5 as in the prior art. Further, in order to introduce the water treatment system 1 according to the present invention into an existing water purification plant, it is only necessary to lay a floc forming pipe 9 having a simple structure between the existing landing well 2 and the existing sedimentation basin 6. Sufficient and does not require major remodeling. Furthermore, since the size of the floc forming pipe 9 can be changed depending on the amount of the water to be treated requiring purification treatment, the water treatment system 1 according to the present invention can be applied to both large and small sized water treatment systems. Therefore, according to the present invention, the water treatment system 1 can be constructed economically, the space of the entire system can be reduced, and the water treatment system 1 suitable for the installation site can be provided. it can.

The floc forming pipe 9 has a simple structure in which a plurality of baffle plates are provided in the pipe although the pipe diameter gradually changes, and a stirrer for stirring the water to be treated is installed. do not have to. In addition, the flock forming tube 9
Since the water to be treated flows in the landing well 2 by utilizing the potential energy of the water to be treated in the landing well 2, the water to be treated flows in the floc forming pipe 9, so that there is no need to provide a power source such as a transport pump. In addition, since the water to be treated is always flowing in the floc forming pipe 9, the flocs 20 in the water to be treated do not accumulate in the floc forming pipe 9, but the flocs 20 in the floc forming pipe 9 related to the accumulation of the flocs 20. No inspection or cleaning is required.

Further, polysilica iron 1 used as a coagulant
6 has less influence on the human body and the environment than the aluminum-based coagulant 15.

FIG. 3 shows that polysilica iron (PSI) is used as a flocculant.
16 is a table comparing floc cohesion, floc sedimentation, and floc strength when using iron trichloride (FeCl ₃ ) and aluminum sulfate (Al (SO ₄ ) ₃ ), respectively. As shown in FIG. 3, floc cohesiveness, floc sedimentation, and floc strength are all
Polysilica iron 16> iron trichloride> aluminum sulfate. Therefore, the following can be considered by using polysilica iron 16 as the coagulant.

That is, when the polysilica iron 16 is used as the flocculant, the polysilica iron 16 has a strong crosslinking action, so that the coagulability of the colloid particles in the water to be treated is very good, and the formation time of the floc 20 is long. Be shorter. In addition, since the polysilica iron 16 can form flocs 20 by aggregating the colloid particles in the water to be treated more efficiently than using a coagulant such as iron trichloride or aluminum sulfate, the suspended component Can be effectively removed from the water to be treated. Further, by setting appropriate flocculation conditions, the floc 20 grows even during stirring, so that the floc 20 can grow even while the water to be treated flows through the floc growth region 23 of the floc forming tube 9. It is possible to reduce the time required for the water purification treatment.

The floc 20 formed and grown using polysilica iron 16 as the flocculant has a higher density and better sedimentation than the case where a flocculant such as iron trichloride or aluminum sulfate is used. Therefore, the floc 20 can be easily settled and removed from the water to be treated, and even if the water to be treated in which the floc 20 has settled is stirred, the floc 20 that has settled does not float. Furthermore, since the floc 20 formed and grown using the polysilica iron 16 as a coagulant has a large strength, the floc 20 once formed does not break and diffuse in the water to be treated.

Furthermore, when polysilica iron 16 is used as a coagulant, it is possible to coagulate cryptosporidium pathogens, etc., which were difficult to coagulate with the aluminum coagulant 15, and to precipitate from the water to be treated.

Next, a modified example of this embodiment will be described. FIG. 4 is a configuration diagram showing a modified example of the floc forming tube of the present embodiment.

As shown in FIG. 4, a part 24 of the water to be treated, which is pumped by a transport pump (not shown), flows together with the polysilica iron 16 from the coagulant injection pipe 8 through the coagulant mixing area 21 of the floc forming pipe 9. It may be injected into the water to be treated.

The other structure is substantially the same as the embodiment shown in FIGS. In FIG. 4, the same portions as those of the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description is omitted.

According to the present modified example shown in FIG. 4, the water to be treated flowing in the floc forming pipe 9 is separated from the baffle plates 12a, 12a.
The colloid particles in the water to be treated form flocs 20 because the polysilica iron 16 diffuses in the water to be treated by diverting by colliding with b, 12c, 12d. In particular, since a part of the water to be treated 24 pumped by the transport pump is injected into the water to be treated in the floc forming pipe 9 together with the polysilica iron 16, the water to be treated mixed with the polysika iron 16 is more violently in each case. Baffle plates 12a, 12b, 12c, 1
Collide with 2d. Thereby, the diffusion of the polysilica iron 16 and the formation and growth of the flocs 20 are further promoted, and the colloid particles in the water to be treated are more effectively subjected to the precipitation treatment.

[0056]

As described above, according to the present invention,
The floc forming tube used in the water treatment system is a flocculant mixing region for injecting a flocculant into the water to be treated, and a floc forming region for forming flocs in the water to be treated by the flocculant,
Since it has a simple structure consisting of a floc growth region for growing flocs, it is possible to prevent the entire water treatment system from being enlarged, and to shorten the time required for purification treatment of the water to be treated. Further, by using the polysica iron as the coagulant, the purification performance of the water to be treated can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a water treatment system having a coagulation-sedimentation step, a filtration step, and a disinfection step according to the present invention.

FIG. 2 is a configuration diagram showing a floc forming tube used in the coagulation sedimentation step of the water treatment system according to the present invention.

FIG. 3 is a chart comparing floc aggregation, floc sedimentation, and floc strength when using polysilica iron, iron trichloride, and aluminum sulfate as flocculants.

FIG. 4 is a configuration diagram showing a modified example of the floc forming tube.

FIG. 5 is a configuration diagram showing a conventional water treatment system employing a rapid filtration method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water treatment system 2 Landing well 2a Communication pipe 3 Mixing pond 4 Raw water culvert 5 Floc formation pond 6 Sedimentation pond 6a Inclined plate device 7 Filtration pond 7a Filter sand 7b Lower water collecting device 8 Flocculant injection pipe 9 Floc formation pipe 10 Flash mixer DESCRIPTION OF SYMBOLS 10a Motor 11 Flocculator 11a Motor 12a 1st baffle 12b 2nd baffle 12c 3rd baffle 12d 4th baffle 15 Aluminum coagulant 16 Polysilica iron 17 Sedimentary culvert 18 Discharge pipe 19 Disinfection pipe 20 Flock 21 Coagulant mixing area 22 Flock formation area 23 Flock growth area 24 Part of water to be treated

Continued on the front page (72) Inventor Keiichi Sato 3-2-34 Ningyo, Kounosu-shi, Saitama (72) Inventor Atsushi Masuko 4-19-17 Hamadayama, Suginami-ku, Tokyo F-term (reference) 4D015 BA09 BA29 BB05 CA14 DA17 EA06 EA32 FA02 FA16

Claims (5)

[Claims] A water treatment system for injecting a coagulant into water to be treated and subjecting the water into which the coagulant has been injected to a sedimentation treatment, wherein a water landing well into which the water to be treated flows and a coagulant are mixed. A sedimentation basin that sediments the water to be treated, and a floc forming pipe that connects between the landing well and the sedimentation basin, the floc forming pipe is a coagulant mixing region that injects the coagulant into the water to be treated, A water treatment system comprising: a floc forming region for forming flocs in water to be treated with a coagulant; and a floc growing region for growing flocs. 2. The water treatment system according to claim 1, wherein the pipe diameter of the floc forming pipe increases from the flocculant mixing area to the floc growth area. 3. The water according to claim 1, wherein the floc forming pipe is provided with one or more baffles for inhibiting the flow of the water to be treated in the floc forming pipe. Processing system. 4. The water according to claim 1, wherein the coagulant injected into the water to be treated in the coagulant mixing region of the floc forming tube is a silica-based iron salt coagulant. Processing system. 5. A floc forming pipe for forming flocs in water to be treated, a flocculant-mixing region for injecting a flocculant into the water to be treated, a floc forming region for forming flocs in the water to be treated by the flocculant, And a flock growth region for growing the flock.