JP2004141773A - Flocculation and precipitation equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make always and stably demonstrable the excellent functions of a high speed flocculation and precipitation equipment, that is, a high speed treatment function and a water quality improvement function by always monitoring the concentration of particulates in a flocculation tank and preferably keeping the concentration automatically within a target concentration range. <P>SOLUTION: The flocculation and precipitation equipment having the flocculation tank for flocculating suspended solids in raw water into a flock by the addition of a flocculant and the particulates and a precipitation tank which precipitates the flock in water from the flocculation tank to separate the flock from treatment water, is characterized by being provided with a densitometer which can continuously measure the concentration of the particulates in the flocculation tank. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coagulation sedimentation apparatus for separating suspended matter in raw water into sludge and treated water by coagulation sedimentation, and in particular, adding particulate matter, circulating and forming a suspended matter into flocs to quickly sediment. TECHNICAL FIELD The present invention relates to a technique for allowing a particulate substance to be constantly maintained and controlled at a concentration appropriate for processing in a coagulation sedimentation apparatus which is capable of performing high-speed processing.
[0002]
[Prior art]
A coagulation tank for coagulating a suspended substance in raw water as floc by adding a coagulant and a particulate matter; and a sedimentation tank for precipitating floc in the water introduced from the coagulation tank and separating it into treated water and floc. There is known a coagulation / sedimentation apparatus capable of performing a treatment at a high linear speed of 30 to 100 m / h.
In this high-speed coagulation sedimentation apparatus, the floc settled and separated in the sedimentation tank is separated into sludge and particulate matter by a separator such as a cyclone, and the particulate matter is returned to the coagulation tank and recycled. Has become.
[0003]
In such a coagulation sedimentation apparatus, in order to keep the quality of treated water good and stable, the concentration of particulate matter in the coagulation tank (this is approximated by the concentration of sludge in the coagulation tank) is within a certain appropriate range (usually, 5 to 200 g / L), and the sludge concentration is measured as an operation management. If the sludge concentration is out of this range or expected to be soon, the granular material is removed. It is necessary to supply the coagulation tank.
[0004]
In the operation of the coagulation-sedimentation apparatus using the above-mentioned circulating granules, the concentration of the granules in the coagulation tank is reduced in the long term unless the granules are intentionally supplied. This is because the separation of the sludge and the particulate matter in a separator such as a cyclone is not complete, and a part of the granular matter is discharged out of the system together with the sludge or mixed into the treated water and flows out. . In order to keep the quality of the treated water good and stable, it is important to keep the concentration of the particulate matter (sludge concentration) in the flocculation tank at a certain value or more (usually 5 g / L or more). It is required to control the concentration so as not to fall below a certain value, such as by measuring and replenishing particulate matter as needed. Conventionally, for such a concentration measurement for management, water was sampled from a flocculation tank, that is, a floc forming tank, via a sampling cock or the like, and was manually measured. However, in the manual measurement, a large error may occur depending on the method of water sampling, and it is difficult to strictly control the concentration. In addition, the measurement requires several hours and the operation is complicated.
[0005]
As a technique different from the high-speed coagulation and sedimentation apparatus described above, a densitometer capable of measuring the concentration of a turbid component in a liquid to be measured with high accuracy using diffuse reflection light of a laser beam is known. It is known (for example, Patent Document 2).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-317215 (Claims)
[Patent Document 2]
JP-A-2002-98637 (Claims)
[0007]
[Problems to be solved by the invention]
The object of the present invention is to pay attention to the problems in the high-speed coagulation and sedimentation apparatus using the above-mentioned granules in circulation, and to constantly monitor the concentration of the granules to be controlled in the coagulation tank, preferably within the target concentration range. The purpose of the present invention is to make it possible to constantly and stably exhibit the excellent function of the high-speed coagulation and sedimentation apparatus, that is, the function of obtaining high-speed treatment and excellent quality of treated water.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an aggregating and settling apparatus according to the present invention comprises an aggregating tank for aggregating suspended substances in raw water as flocs by adding a flocculant and particulate matter, and a method for sedimenting flocs in water introduced from the aggregating tank. A coagulation sedimentation apparatus having a sedimentation tank for separating treated water and floc, wherein a concentration meter capable of continuously measuring the concentration of the particulate matter is provided in the coagulation tank.
[0009]
This coagulation-sedimentation apparatus can be configured as a coagulation-sedimentation apparatus capable of performing high-speed processing in which the linear velocity of the processing in the above-mentioned sedimentation tank is 30 to 100 m / h.
[0010]
The concentration meter is not particularly limited as long as it is a concentration meter capable of continuously measuring the concentration of the particulate matter in the coagulation tank.From the viewpoint of measurement accuracy and the measurement target range, particularly, an optical fiber for emitting laser light and a light receiving device are used. A plurality of optical fibers are bundled together to form a single sensor unit, and the concentration of turbid components in the liquid to be measured is detected by detecting the diffuse reflection of laser light emitted toward the liquid to be measured. It preferably comprises a densitometer for measuring. The densitometer having such a configuration can be configured to have at least a concentration measurement target range of 1 to 30 g / L. Since the concentration of the particulate matter in the coagulation tank is generally preferably controlled within the range of 5 to 20 g / L, the above-mentioned densitometer is suitable for measuring the concentration near the control value of such a particulate matter.
[0011]
Further, in the coagulation / sedimentation apparatus according to the present invention, based on the measurement information from the densitometer, a particulate matter automatic supply system for automatically replenishing the particulate matter in the coagulation tank so that the concentration of the particulate matter is within a target concentration range. It is preferable to have The target concentration range is preferably set within the range of 5 to 20 g / L as described above. The configuration of the automatic granular material supply system is not particularly limited, but, for example, a granular material storage tank, a unit for measuring the granular material sent out from the granular material storage tank, and a granular material sent to the flocculation tank as a slurry of the granular material with water. It can be configured to include a transfer means.
[0012]
In the coagulation / sedimentation apparatus according to the present invention as described above, since a concentration meter capable of continuously measuring is provided in the coagulation tank, the concentration and concentration of the particulate matter in the coagulation tank are sampled and analyzed in the conventional manner. Instead, it can be continuously measured and monitored in the processing system, and the concentration of particulate matter can be constantly maintained within a target range according to the measured value. In addition, if an automatic supply system for particulate matter is provided, it is possible to automatically replenish the particulate matter as needed, and the concentration of the particulate matter in the coagulation tank is always stable and controlled within the target range. Is done. As a result, a high-speed coagulating sedimentation apparatus that forms flocs using the particulate matter and can quickly settle the flocs can be always operated under optimal conditions without performing a complicated analysis operation. Excellent treated water quality can be obtained stably.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a coagulation / sedimentation apparatus according to one embodiment of the present invention. The coagulation / sedimentation apparatus 1 includes a coagulation tank 2 and a precipitation tank 3 disposed adjacent to the coagulation tank 2. In this embodiment, an inorganic coagulant mixing tank 4 is provided in front of the coagulation tank 2. Raw water 6 is supplied to the inorganic coagulant mixing tank 4 via a raw water supply line 5, and in this embodiment, PAC 7 (polyaluminum chloride) is injected into the raw water supply line 5 as an inorganic coagulant. The raw water into which the PAC 7 has been injected is stirred by the stirrer 8 in the inorganic coagulant mixing tank 4, and PAC 7 is mixed with the raw water as the inorganic coagulant. Raw water mixed with the inorganic coagulant is introduced from the inorganic coagulant mixing tank 4 through the overflow weir 9 into the coagulation tank 2 from below. The polymer flocculant 10 is added into the flocculation tank 2 and is stirred by the stirrer 11 in the blanket 12 of the flocculation tank 2 together with the particulate matter described later. The polymer coagulant 10 can be injected into the coagulation tank 2 through an introduction line 13.
[0014]
As the inorganic coagulant 7, besides the above-mentioned polyaluminum chloride (PAC), for example, ferric chloride, ferric sulfate or the like can be used. As the polymer coagulant 10, for example, nonionic, anionic or amphoteric Can be used. Examples of the anionic polymer coagulant include a polymer of acrylic acid or a salt thereof, a copolymer of acrylic acid or a salt thereof and acrylamide, and a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid salt And a tertiary copolymer of acrylic acid or a salt thereof, acrylamide and 2-acrylamido-2-methylpropanesulfonate, and a partial hydrolyzate of polyacrylamide, but are not particularly limited thereto. A typical nonionic polymer coagulant includes polyacrylamide, but is not particularly limited thereto. Examples of the amphoteric polymer flocculant include at least one cationic monomer such as tertiary salt and quaternary salt of dimethylaminoethyl (meth) acrylate (eg, methyl chloride salt), acrylic acid and a salt thereof. (Salts such as sodium and calcium), copolymers of at least one anionic monomer such as 2-acrylamido-2-methylpropanesulfonate (salts such as sodium and calcium), or at least one of Examples include tertiary or quaternary or higher copolymers of at least one kind of cationic monomer and at least one kind of anionic monomer and at least one kind of nonionic monomer such as acrylamide, It is not particularly limited to these. The range of the molecular weight of the polymer flocculant is not particularly limited, but is preferably in the range of 5,000,000 to 20,000,000. These polymer flocculants can be used alone or as a mixture. The amount of the polymer flocculant to be added is generally about 0.3 to 2 mg / l from an economic viewpoint.
[0015]
Sand 14 as granular material is added into the coagulation tank 2 and functions as a sedimentation promoting material in the coagulation sedimentation device. The addition amount is initially added, for example, so that the concentration of the sand 14 in the flocculation tank 2 becomes 5 g / L or more, and as described later, a shortage is replenished in a timely manner so as to maintain a predetermined concentration. The addition amount is preferably in the range of 5 g / L to 200 g / L, but it is most preferable from an economic viewpoint that a predetermined treatment effect can be exhibited with a small addition amount. It is preferable to control or control the concentration of the particulate matter in 2 within a range of 5 to 20 g / L.
[0016]
In the flocculation tank 2, the suspended substance in the raw water is flocculated as flocs containing the inorganic flocculant 7, the polymer flocculant 10, and the sand 14 by stirring in the blanket 12 by the stirrer 11.
[0017]
In this flocculation, the inorganic flocculant 7 flocculates the suspended substance to form fine flocs, and the polymer flocculant 10 becomes entangled and grows into larger flocs. And grows into flocs which are relatively large as a whole and have a large specific gravity and are easy to precipitate.
[0018]
Flock growth proceeds in a region above the stirring blades of the stirrer 11 rather than near the stirring blades. The lower portion 2a of the flocculation tank 2 is formed in a cone shape narrowing downward, and the flow velocity of the rotating flow of the water to be treated, which rotates with the rotation of the stirring blade, is increased in the lower portion 2a. Precipitation and accumulation of floc on the lower portion 2a of the fin are properly prevented.
[0019]
In the blanket 12 in the coagulation tank 2, a densitometer 15, particularly a sensor unit 16 thereof, is provided. Outside the coagulation tank 2, a converter of the densitometer 15 and a concentration display unit 17 are provided. The densitometer 15 is a densitometer capable of continuously measuring the concentration of particulate matter in the coagulation tank 2. The sensor unit 16 of the densitometer 15 is installed in a portion (flock blanket 12) of the flocculation tank 2 where the flocs in which the particulate matter has absorbed are retained (flock blanket 12). Any place may be used as long as it does not cause any problem. However, in order to increase the measurement accuracy, it is desirable that the blanket 12 be installed at the middle position and at a position separated from the wall surface of the tank by 2 cm or more. The main body of the densitometer, that is, the main body of the densitometer including the converter and the concentration display section 17 does not need to be near the coagulation / sedimentation apparatus 1 (in particular, the coagulation tank 2). It should be installed in a place that is easy to see and manage.
[0020]
In this embodiment, the densitometer 15 comprises a densitometer having a basic configuration as shown in FIG. In FIG. 2, the concentration meter 15 has a tip in the form of a sensor, and is attached so that the tip faces, for example, the inside of the coagulation tank 2. The densitometer 15 is a diffuse reflection light of the laser irradiation light 45 emitted toward the turbid component 44 (in the present invention, the flocculant for measuring the concentration of the particulate matter) in the liquid 43 to be measured in the flocculation tank 2. This is configured as a diffuse reflection light type densitometer that detects the concentration of the turbid component 44 in the liquid 43 to be measured by detecting 46.
[0021]
In this embodiment, a laser light emitting diode 47 (which may be abbreviated as a laser diode) that emits high-intensity laser light in a specific wavelength range suitable for laser light emission is used as a laser light source, and an oscillator is used. Laser light is emitted in a predetermined pulse form by pulse driving by the driving circuit 48 provided. The laser light emitted from the laser light emitting diode 47 is incident on the incident ends of a large number of light emitting optical fibers 51 bundled and held by an optical fiber fixing bracket 50 via a laser light diffusion plate 49. The laser light is applied to the incident end of the light emitting optical fiber 51 in a state of being uniformly diffused by the laser light diffusion plate 49.
[0022]
A large number of light emitting optical fibers 51 and a substantially equal number of light receiving optical fibers 52 are bundled to constitute one sensor unit 53. The bundled light-emitting optical fiber 51 and light-receiving optical fiber 52 are held, for example, in a state in which their relative positions are fixed in a fixture 54, and are formed on the sensor surface 55 such that the positions of the tip surfaces of the optical fibers are aligned. . From the sensor surface 55, the light is guided through the light emitting optical fiber 51, and the laser light emitted from the emission end of the light emitting optical fiber 51 is irradiated toward the liquid to be measured 43, and the turbid component in the liquid to be measured 43 The laser light that has been diffused and reflected at 44 is received at the incident end of the light receiving optical fiber 52. In the present embodiment, the reception and emission of the laser light on the sensor surface 55 are performed through a glass plate 56 provided on the sensor surface 55.
The material of the glass plate 56 is not particularly limited, but sapphire glass that is hard and hard to be scratched, is chemically stable, has excellent acid resistance, alkali resistance, solvent resistance, and is thermally stable is preferable. Further, it is preferable that the surface of the glass plate 56 on the side of the liquid 43 to be measured is mirror-finished because dirt by sludge hardly adheres and scratches by sludge hardly occur. Although FIG. 2 shows the glass plate 56 as a flat plate, a lens having an appropriate focal length may be employed instead of the glass plate 56. As the lens, a plano-convex lens or the like having a lens function by forming the sensor surface side as a flat surface and the other surface side as a convex surface is preferable.
[0023]
The diffusely reflected light of the laser beam received from the incident end of the light receiving optical fiber 52 is guided through the light receiving optical fiber 52, and is emitted from the emission end which is the opposite end. A large number of light receiving optical fibers 52 are held in a bundled state by an optical fiber fixing bracket 57 also at the end of the light receiving optical fiber 52 on the emission end side.
[0024]
In this embodiment, the diffuse reflected light emitted from the emission end of the light receiving optical fiber 52 is received by a photodiode 59 as a reflected light receiving element through a visible light cut filter 58, and the light amount is detected. By disposing the visible light cut filter 58, the influence of disturbance light (for example, disturbance light from a fluorescent lamp or the like) on the density measurement can be suppressed. In the present embodiment, the received light amount signal of the photodiode 59 is amplified by the amplifier circuit 60 and output as a signal having a magnitude suitable for density measurement, and is displayed as a detected density on an appropriate display device as necessary. Is done.
[0025]
As the arrangement of the light emitting optical fiber 51 and the light receiving optical fiber 52 on the sensor surface 55 of the sensor section 53, a random arrangement, a concentric arrangement, a form in which each is arranged in a semicircle, or the like can be adopted. The total number of optical fibers on the sensor surface 55 is appropriately set, for example, within a range of about 100 to 50,000. Even if each optical fiber is an ultra-fine optical fiber and the measurement is impossible due to the shortage of light with a single core, for example, 1500 optical fibers for light emission and 1500 optical fibers for light reception, about 3000 in total. By doing so, a sufficiently large light emission amount and light reception amount can be obtained.
[0026]
As described above, a large number of light emitting optical fibers 51 and light receiving optical fibers 52 are bundled to form one sensor section 53, and these are arranged in a predetermined form on the sensor surface 55, so that each optical fiber is Even if it is thin and the amount of received light is small, it is possible to obtain a sufficiently large amount of emitted light and received light as a whole by bundling a large number. As a result, it is possible to avoid a shortage of light quantity in both light emission and light reception in the density measurement, and to obtain a light quantity necessary and sufficient for obtaining high sensitivity. More specifically, a sufficient quantity of light can be obtained by setting the number to 100 to 50,000, particularly 1000 or more, and more preferably about 3000 in total.
[0027]
Further, since the light emitting optical fiber 51 and the light receiving optical fiber 52 bundled in a large number are each made of an ultrafine optical fiber, the light span in the concentration measurement can be reduced to the limit. For example, in the case of random arrangement, when the diameter of the optical fiber is 30 μm, the light span between the light emitting optical fiber 51 and the light receiving optical fiber 52 adjacent to each other is about 30 μm, and an extremely small light span can be obtained. Compared to a mode having a long light span of about 5 mm, the ratio of the light span is actually 30: 5000 = 1: 167. That is, a sensitivity as high as 167 times as high as the sensitivity for density measurement can be obtained. As a result of the significant increase in sensitivity, high sensitivity is measured not only when the concentration of the turbid component is low, but also when the concentration is higher than 1%, especially higher than 3%, and even higher than 5%. It becomes possible to do. In addition, since it has high sensitivity, it can favorably follow changes in the properties and concentration of the turbid component, and stable and accurate concentration measurement can be performed.
[0028]
In addition, since a laser light emitting diode 47 that emits high-intensity laser light in a specific wavelength region is used instead of a normal LED as a light source of the laser light, sufficient intensity as a light source is obtained as compared with other light sources. As a result, excellent reproducibility can be obtained, and at the same time, excellent pulse drive characteristics can be obtained in which a target frequency characteristic can be accurately obtained at the time of pulse drive and a desired light emission can be sharply performed. As a result, by using the densitometer 15, the concentration of the turbid component in the flocculation tank 2 can be continuously measured with extremely high sensitivity and high accuracy. The concentration of the turbid component in the coagulation tank 2 represents the concentration of the particulate matter 14 in the coagulation tank 2.
[0029]
Now, referring again to FIG. 1, while the concentration of the particulate matter in the flocculation tank 2 is continuously measured as described above, the water to be treated including the flocculated flocs grown in the flocculation tank 2 is over-flowed. It is introduced into the precipitation tank 3 via the weir 18. In the sedimentation tank 3, the flocs in the introduced water are sedimented downward, and the sedimented flocs are separated from the upper treated water 19. A plurality of inclined plates 20 are juxtaposed at the upper part in the settling tank 3 to prevent the floc from flowing out together with the treated water 19.
[0030]
The bottom of the settling tank 3 is connected to a drawing line 21 for drawing out the settled flocs, and the settled flocs are drawn out by a sludge drawing pump 22. The pulled-out floc is sent to a cyclone 23 as a separator, and is separated into sludge 24 and particulate matter 14 by centrifugation in the cyclone 23. The separated particulate matter 14 is returned to the flocculation tank 2 again and used for circulation.
[0031]
In the coagulation / sedimentation apparatus 1 configured as described above, the concentration of the particulate matter in the coagulation tank 2 can always be automatically measured by the densitometer 15, so that the time and effort for the measurement are reduced as compared with the conventional sampling water sampling. Omitted, the measured concentration is output quickly and continuously.
Therefore, the measurement result can be fed back to the management and control of the concentration of the particulate matter without delay, and the concentration can be easily and stably maintained within the target concentration range with high accuracy.
[0032]
Further, since the sensor unit of the concentration meter 15 is installed in the sludge in the flocculation tank 2, there is no error in water sampling, and the concentration can be always measured with high accuracy. In addition, since the measurement can be performed continuously, the tendency can be accurately grasped before the particulate matter concentration goes out of the control range and the quality of the treated water deteriorates. Can be constantly maintained in good water quality.
[0033]
FIG. 3 shows a coagulation-sedimentation apparatus 31 according to another embodiment of the present invention.
In the present embodiment, the concentration of the particulate matter in the flocculation tank 2 falls within the target concentration range (for example, 5 to 20 g / L) based on the measurement information from the densitometer 15 in the coagulation sedimentation apparatus shown in FIG. It has a granular material automatic supply system 32 for automatically replenishing granular materials.
[0034]
The automatic granular material supply system 32 includes a granular material storage tank 33, a metering / sending device 34 as a means for measuring the granular material sent out from the granular material storage tank 33, and a granular material that feeds the granular material into the flocculation tank 2 as a slurry with water. An object transfer means 35 is provided. In the present embodiment, the particulate matter transfer means 35 includes a receiving hopper 36 for containing the particulate matter from the fixed-quantity sending device 34, a treated water tank 37 for containing treated water in the coagulating sedimentation device 31, and a treated water tank 37. A treated water pump 38 for extracting the treated water and sending it into the receiving hopper 36 and sending it out as transfer water; a hopper ejector 39 for sucking and pumping particulate matter from inside the receiving hopper 36 in the form of a water slurry; A particulate supply line 40 for supplying the water slurry into the flocculation tank 2; Based on the concentration measurement signal from the densitometer 15, an operation instruction signal from a control system 42 including a control device 41 is sent to the treated water pump 38 and the fixed-rate sending device 34, whereby these operations are controlled, and The particulate matter is automatically replenished such that the concentration of the particulate matter in is maintained within the target concentration range.
[0035]
In the present embodiment, the automatic granular material supply system 32 is configured as described above. However, the present invention is not limited to this configuration as long as the apparatus can supply the set replenishment amount from the storage tank of the granular material to the coagulation tank. Further, in consideration of the energy required for transferring the particulate matter to the coagulation tank, it is desirable that the automatic supply device is installed at a position as close as possible to the coagulation and sedimentation device.
[0036]
In the automatic granular material supply system 32 according to the present embodiment, a predetermined supply amount of the granular material is put into the receiving hopper 36 from the granular material storage tank 33 by the metering / sending device 34. At the same time, the water supply pump (process water pump 38) is operated, and a part of the water supply is injected from the branch pipe into the receiving hopper 36 from the upper portion, passes through the hopper ejector 39, and passes through the particulate supply line 40 to form the water slurry. The granular material is transferred to the coagulation tank 2 by. It is efficient to use treated water for water supply for transfer, but tap water or the like may be used. Further, as the metering / sending device 34, the granular material is dropped downward by a predetermined amount by controlling the number of rotations by a rotor system (a rotating rod having a groove parallel to the rotation axis) attached to the bottom of the granular material storage tank 33. Is the easiest to use. However, the present invention is not limited to this method as long as the set amount of granular material can be metered and supplied. It is desirable that the injection point of the water slurry of the granular material is injected into a floc blanket of the flocculation tank 2 and immediately absorbed into the floc of the inorganic flocculant and the polymer flocculant.
[0037]
In the control, the replenishment start concentration and the replenishment amount are set (the replenishment amount is set to the target concentration after replenishment). When the concentration drops to the replenishment start concentration, the automatic particulate supply system is activated, and replenishment of the set amount of particulates is started.
[0038]
In the coagulating sedimentation apparatus 31 having the automatic particulate matter supply system 32, the sludge concentration (the concentration of the particulate matter in the flocculation tank 2) is always accurately measured, and the replenishment amount of the particulate matter is determined based on the measured value. Since it is calculated and automatically replenished into the flocculation tank 2, the control of the concentration of the particulate matter is greatly reduced.
[0039]
Further, since the concentration of the particulate matter can be stably maintained at a low value (near the lower limit of the control value, for example, about 5 g / L), the separation of the sludge and the particulate matter is efficiently performed in a separator such as a cyclone. In addition, the loss of the granular material can be kept low. In addition, the cost for replenishing particulate matter can be reduced accordingly.
[0040]
【Example】
Example 1
A treatment test using a coagulating sedimentation apparatus shown in FIG. 1 was performed using certain river water as raw water. Coagulation sedimentation equipment:
Inorganic flocculant mixing tank (0.5m ³ ): Sulfuric acid for pH adjustment and an inorganic coagulant polyaluminum chloride (hereinafter, PAC) were injected into the inflow section of this tank.
Coagulation tank (0.5m ³ ): At the inlet of the main tank, an organic polymer flocculant (nonionic polyacrylamide) and a granular material separated by a cyclone are injected.
Sedimentation tank (0.5 m ³ ): Upflow type inclined plate sedimentation tank (surface area 0.5m × 0.5m)
Densitometer: Install the sensor part by immersing it in the floc blanket inside the coagulation tank.
The main unit is installed outside the device.
[0041]
Operating conditions:
Treated water volume: 10m ³ / Time
Sedimentation tank surface area load: 40m ³ / M ² /Time
PAC injection rate: 30 mg / L
Organic polymer flocculant injection rate: 0.6 mg / L (nonionic polyacrylamide, molecular weight 1600 × 10 ⁴ )
Circulation flow rate: 0.6m ³ /Time
Particulate matter concentration at start of experiment: 7.0 g / L
[0042]
result:
During the test period, the raw water fluctuated randomly in the range of 4 to 20 degrees turbidity.
One month after the start of the experiment, the treated water turbidity was stable at 0.2 to 0.3 degrees. The indicated value of the concentration of the particulate matter was 7.0 g / L at the beginning of the experiment, but decreased to 4.5 g / L after one month. Ten days later, it decreased to 3.5 g / L.
After about one month, the turbidity of the treated water gradually increased, and rose to 0.6 degrees on the day when the concentration of the particulate matter became 3.5 g / L. This increase was accompanied by a decrease in the concentration of the particulate matter, and when the concentration became 5.0 g / L or less, the turbidity of the treated water tended to deteriorate. In order to confirm the indicated concentration value, water from a floc blanket was sampled, and the concentration of the particulate matter was separately measured by a manual solid matter measurement method. The concentration at the beginning of the experiment was 7.2 g / L, one month. After that, the concentration was 4.3 g / L, and the concentration ten days later was 3.9 g / L, and the indicated concentration values of the densitometer almost coincided therewith, and it was confirmed that there was no large deviation in the indicated values.
[0043]
When the concentration dropped to 3.5 g / L, 1.75 kg of the particulate matter was supplied to the coagulation tank so that the concentration became 7.0 g / L. After the replenishment, the turbidity of the treated water was again 0.2 to 0.3 degrees and remained stable. Three weeks after the replenishment, the concentration of the particulate matter became 5.0 g / L, so 1 kg of the particulate matter was replenished into the coagulation tank, and the concentration of the particulate matter was adjusted to 7.0 g / L. It changed from 0.2 to 0.3 degrees before replenishment and 0.2 to 0.3 degrees after replenishment. That is, based on the concentration indication value of the densitometer, it was understood that the concentration of the particulate matter had decreased, and the particulate matter could be supplied before the turbidity of the treated water deteriorated.
[0044]
Example 2
A treatment test was performed using the same river water as in Example 1 as raw water.
Coagulation sedimentation apparatus: Same as in Example 1.
Densitometer: Same as in Example 1.
Granular material automatic supply system:
Granule replenishment start concentration: 5.0 g / L
Granular material replenishment amount: 1.0 kg (target concentration: 7.0 g / L)
Transfer water: Coagulated sediment treated water stored in a treated water tank is used.
Transfer water flow rate: 20 L / min x 6 minutes
Metering and sending device: 200 kg / min × 5 minutes, 1.0 kg was transferred to the hopper ejector.
[0045]
result:
During the test period, the raw water fluctuated irregularly in the turbidity range of 4 to 18 degrees, almost as in Example 1.
After the start of the test, the treated water turbidity was stable at 0.2 to 0.3 degrees. The indicated value of the concentration of particulate matter was 7.0 g / L at the beginning of the experiment, but decreased to 5.0 g / L of the starting concentration after 3 weeks. When the automatic replenishment system was operated and 1.0 kg of the granular material was supplied to the coagulation tank, the concentration of the coagulation tank was restored to 7.0 g / L. Even after replenishment, the treated water turbidity was stable at 0.2 to 0.3 degrees. That is, in this test, before the quality of the treated water deteriorated, the replenishment of the particulate matter could be automatically performed, and the quality of the treated water could be stably maintained. In addition, the labor involved in managing and replenishing the concentration of particulate matter has been greatly reduced.
[0046]
【The invention's effect】
As described above, according to the coagulation / sedimentation apparatus according to the present invention, the concentration of the particulate matter in the coagulation tank can be automatically measured with high accuracy at all times, which greatly reduces the time and effort required for measurement as compared with the conventional sampling water sampling. And the concentration can be measured directly in the coagulation tank, so that the measurement accuracy can be greatly improved, and the concentration of the particulate matter can be constantly and stably maintained within the target concentration range. As a result, the excellent high-speed treatment function of the high-speed coagulation and sedimentation apparatus and the function of obtaining excellent treated water quality can always be stably exhibited.
[0047]
In particular, if an automatic supply system for particulate matter is provided, in addition to the automatic measurement of the concentration of particulate matter, the replenishment of particulate matter necessary to maintain the concentration within the target concentration range can be performed automatically, and the target The concentration can be maintained within the range, the amount of the circulating granules used can be minimized, and the operating cost can be reduced.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a coagulation / sedimentation apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram showing a basic configuration of a densitometer used in the apparatus of FIG.
FIG. 3 is an overall configuration diagram of a coagulation / sedimentation apparatus according to another embodiment of the present invention.
[Explanation of symbols]
1 Coagulation sedimentation equipment
2 Coagulation tank
2a Lower part of coagulation tank
3 Sedimentation tank
4 Inorganic flocculant mixing tank
5 Raw water supply line
6 Raw water
7 Inorganic flocculants
8 Stirrer
9 Overflow Wet
10 Polymer flocculant
11 Stirrer
12 blanket
13 Introduction line to coagulation tank
14. Sand as granular material
15 Densitometer
16 Sensor section
17 Converter and density display
18 Overflow Wet
19 Treated water
20 Inclined plate
21 Drawing line
22 Sludge extraction pump
23 Cyclone as separator
24 sludge
31 Coagulation sedimentation equipment
32 Automatic supply system for granular materials
33 granular material storage tank
34 Metering transmitter
35 Granular material transfer means
36 Receiving hopper
37 Treated water tank
38 Treated water pump
39 Hopper ejector
40 granular material supply line
41 Control device
42 Control system
43 Liquid to be measured
44 Suspended components
45 Laser light emitted
46 Diffuse reflected light of laser light
47 Laser light emitting diode
48 Laser drive circuit
49 Laser light diffuser
50 Optical fiber fixing bracket
51 Optical fiber for light emission
52 Optical fiber for receiving light
53 Sensor section
54, 57 Fixing bracket
55 sensor surface
56 glass plate
58 Visible light cut filter
59 Photodiode
60 amplifying circuit

Claims (7)

Coagulation sedimentation equipped with a flocculation tank for flocculating suspended substances in raw water as flocs by adding a flocculant and granules, and a sedimentation tank for sedimenting flocs in water introduced from the flocculation tank and separating them into treated water and flocs The apparatus according to claim 1, wherein a concentration meter capable of continuously measuring the concentration of the particulate matter is provided in the flocculation tank. The coagulating sedimentation apparatus according to claim 1, wherein the linear velocity of the treatment in the sedimentation tank is 30 to 100 m / h. The densitometer, a plurality of optical fibers for emitting laser light and a plurality of optical fibers for receiving light are bundled to form one sensor unit, and the concentration of the turbid component in the liquid to be measured is emitted toward the liquid to be measured. 3. The coagulating sedimentation apparatus according to claim 1, comprising a densitometer for measuring by detecting diffuse reflection of the laser light. The coagulation sedimentation device according to any one of claims 1 to 3, wherein the densitometer has a measured concentration range of at least 1 to 30 g / L. The apparatus according to any one of claims 1 to 4, further comprising an automatic particle supply system for automatically replenishing the particulate matter based on the measurement information from the densitometer so that the concentration of the particulate matter in the coagulation tank falls within a target concentration range. 3. The coagulation sedimentation apparatus according to item 1. The coagulation sedimentation device according to claim 5, wherein the target concentration range is set within a range of 5 to 20 g / L. The granular material automatic supply system includes a granular material storage tank, a unit for measuring the granular material sent out from the granular material storage tank, and a granular material transfer unit for sending the granular material as a slurry with water into the agglomeration tank, The coagulation sedimentation device according to claim 5 or 6.

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