JPH0698247B2 - Float blanket type coagulating sedimentation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an improvement of a floc blanket type coagulation sedimentation device for solid-liquid separation of river water, lake water, wastewater and the like by coagulation sedimentation.

<Prior art> When removing suspended solids from river water, lake water, wastewater, etc.,
A flocculant is added to raw water to flocculate suspended matter in the raw water to form flocs, and the flocs are removed from the water by sedimentation separation to obtain turbid water. Yes, it is widely used due to the advantage of its installation area. As one of the high-speed coagulation-sedimentation devices, there is a floc blanket type coagulation-sedimentation device, and the conventional floc blanket-type coagulation-sedimentation device is shown in FIG. It flows in from the bottom in an ascending flow, collides against the baffle cylinder 3 to mix and stir, and further stirs with a stirring blade 5 rotating by a drive unit 4 to agglomerate suspended substances in the raw water and rise while forming flocs. Then, the flocs in the flocculating liquid are contacted and captured by passing them through the floc blanket layer 6, and the treated water from which suspended substances have been removed is obtained through the trough 7. The excess flocs flow out of the tank from the outflow pipe 25 provided on the side wall of the layer 2.

In another example, as shown in FIG. 4, raw water added with a flocculant flows downward through a raw water pipe 1 into a flocculation chamber 8 provided in the upper center of a tank 2 and is provided in the flocculation chamber 8. In addition, the stirrer 5 rotating by the driving machine 4a stirs the suspended solids in the raw water to form flocs, and the flocculation liquid is blown out from the flocculating chamber 8 rotated by the driving machine 4b. 9 is uniformly jetted over the entire tank 2 and passed through the floc blanket layer 6 in an ascending flow to contactly capture the flocs in the coagulation liquid, and the treated water from which suspended substances have been removed is obtained through the trough 7. is there. The lower part of the flock blanket layer 6 is a flock concentration part.

<Problems to be Solved by the Invention> However, in the above-described conventional device, power consumption is large because power is required, maintenance is complicated because the machine part is included, and the structure is complicated and the equipment cost is high. Had the drawback of.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a floc blanket type coagulation-sedimentation device which does not have a special power part or mechanical part, has a simple structure and is capable of high-speed coagulation-sedimentation treatment. It is a thing.

<Means for Solving Problems> In the present invention, a tubular body having an open upper end and a closed lower end is provided upright in the center of a tank, and a raw water inlet is provided around the lower portion of the tubular body. In a floc blanket-type coagulating sedimentation apparatus in which a treated water outlet is provided above the opening of the tubular body, a precipitation chamber having a flock blanket layer on the outer side of the tubular body, and a flock concentrating chamber on the inner side of the tubular body. Orienting the raw water inlet so that the raw water blown out from at least a part of the raw water inlet blows out in a direction in which a swirl flow occurs in the lower part of the floc blanket layer in the precipitation chamber,
By blowing out the raw water, a swirling flow is given to the flock blanket layer, an inner cylinder having an open lower end is inserted from the opening of the tubular body, and one end of the communication pipe is connected to the upper end of the inner cylinder. The other end opening of the communication pipe is located below the water surface formed in the tank, and due to the water head difference of the water surface, the water in the inner cylinder is constantly discharged from the communication pipe to allow a downward flow into the tubular body. It is characterized by giving.

The present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective explanatory view showing an example of an embodiment of the device of the present invention, in which a cylindrical body 19 having an open upper end and a closed lower end is provided upright at the center of a cylindrical or polygonal columnar tank 2. The outside of the tubular body 19 is the precipitation chamber 11, the inside of the tubular body is the floc concentrating chamber 12, and the raw water pipe 13 communicating with the raw water pipe 1 is provided in the lower portion of the precipitation chamber 11. The raw moisture pipe 13 is usually provided with several outlet pipes 9 each having a raw water inlet 14,
From the opening of the tubular body 19, insert the inner cylinder 24 with the lower end opened and the upper end closed, connect one end of the communication pipe 23 to the upper end of the inner cylinder 24, and open the other end opening of the communication pipe 23. , Communicates with the trough 7 provided above the tank 2, and positions the opening below the water surface formed in the tank 2. Due to the water head difference of the water surface, the water in the inner cylinder is discharged from the communication pipe 23. By constantly discharging, a downward flow is given into the tubular body 19. The upper end position of the tubular body 19 determines the height of the upper surface of the flock blanket layer formed around the tubular body 19, and the height from the bottom plate 10 to the upper end of the tubular body 19 is usually set to 1 ~ 3m, the height from the upper end of the tubular body 19 to the water surface formed in the tank 2
0.1 to 1.5m. In addition, the flock concentrating chamber 12 has a cone-shaped bottom having an inclination equal to or greater than the angle of repose of the flock,
A sludge drawing pipe 20 is erected above the top of the cone. The shapes of the inner wall of the tank 2 and the outer wall of the tubular body 19 give a swirl flow to the lower part of the flock blanket layer formed as described later in the device of the present invention, so that the swirl flow is not attenuated as much as possible, that is, a cylindrical shape. Alternatively, it is desirable that the polygonal column shape has a large number of polygonal column shapes. The direction of the raw water inlet 14 of the blow-out pipe 9 is such that the inflowing raw water causes a swirling flow in the flock blanket layer, that is, as shown in FIG. In the case of the shape, the direction (for example, the direction c) that is more inward than the same direction b as the horizontal tangential direction is desirable. According to the research by the present inventor, the direction of the raw water inlet 14 is more preferably a direction slightly outward from the horizontal tangential direction d of the outer wall of the tubular body 19, for example, near the direction e. This is because even if the direction inward of the direction b is close to the direction b, a swirling flow occurs only in the tank 2 or in the vicinity of the inner wall and almost no swirling flow occurs in the vicinity of the outer wall of the tubular body 19. In addition, the raw water inlet 14 of the outlet pipe 9
In the direction f in which the raw water blown from the water directly collides with the outer wall of the tubular body 19, the flow is attenuated by the collision, and a swirling flow is less likely to occur, which is not preferable.

Although one raw moisture pipe 13 is provided in this embodiment, another raw moisture pipe 13 having a plurality of holes serving as raw water inlets at the bottom may be separately provided below the raw moisture pipe 13. Good.

<Operation of the Invention> In the apparatus of the present invention shown in FIG. 1, raw water added with a coagulant is passed through the raw water pipe 1 and the raw water pipe 13 to blow out a few blow pipes 9.
The raw water inflow port (14) is made to jet out and flow into the lower part of the flock blanket layer formed around the tubular body (19). Since the raw water inlets 14 of the several outlet pipes 9 face inward from the direction b as shown in FIG. 2, the raw water flowing from the raw water inlet 14 is outside the tubular body 19 and in the tank. It is possible to give a swirl flow to the entire doughnut-shaped portion inside 2. More preferably, by making the direction of the raw water inlet 14 of the blow-out pipe 9 slightly outward from the horizontal tangential direction of the outer wall of the tubular body 19, the donut shape between the tubular body 19 and the tank 2 described above is provided. The linear flow velocities of the swirling flow inside and outside the portion can be made substantially the same, and a uniform swirling flow can be given to the entire donut-shaped portion described above. Although the apparatus of the present invention requires that the tubular body 19 be erected at the center of the tank 2, the installation of the tubular body 19 is very important. If the tubular body 19 is not provided in the center of the tank 2, even if a swirl flow is generated in the flock blanket layer, there is a portion in which the swirl flow does not occur in the center of the tank 2. This is because aggregation and floc formation become insufficient, which eventually causes deterioration of the quality of treated water. In the device of the present invention, tank 2
By arranging the tubular body 19 upright in the center of the, the above-mentioned portion where swirl flow does not occur is positively removed, and swirl flow is uniformly generated in the entire floc blanket layer, and the suspended solids in the raw water are aggregated. The flock formation is performed sufficiently. Further, by erection of the tubular body 19, another purpose of always maintaining the upper surface position of the flock blanket layer at a constant height can be achieved.

The raw water that has flowed in from the raw water inlet 14 is subjected to stirring by jetting or swirling flow, and suspended substances in the raw water aggregate to form flocs. Further, the flocs grow and become stronger as they grow due to the collision between the flocculated flocs and the existing flocs in the flock blanket layer, or the collision between the existing flocs.

Then, the flocculating liquid containing the flocs thus grown rises while swirling and reaches the upper portion of the floc blanket layer. The upper part of the floc blanket layer is a floc group suspended and equilibrated to a high concentration, and the flocs in the ascending flocculating liquid are contacted and captured to allow only the suspended water from which suspended substances have been removed to pass through. Is. The lower part of the flock blanket layer is affected by the swirl flow described above, and a strong swirl flow is generated, but the upper part of the flock blanket layer is a gentle swirl flow because the swirl flow from below is attenuated. That is, the rapid agitation and slow agitation generally required for flocculation of the suspension can be continuously formed from the lower part to the upper part of the precipitation chamber. Furthermore, the swirling of the flock blanket layer makes the floc concentration of the flock blanket layer uniform throughout, and the carryover of fine flock can be effectively prevented.

Further, from the opening of the tubular body 19, an inner cylinder 24 having a lower end opened and an upper end closed is inserted below the water surface formed in the tank, and one end of the communication pipe 23 is connected to the upper end of the inner cylinder 24. While connecting, the other end opening of the communication pipe 23 is communicated with a position below the water surface of the trough 7 formed in the tank 2. Therefore, the water in the inner pipe 24 can be constantly discharged from the opening on the trough side of the communication pipe 23 due to the difference in water head of the tank 2, and the water corresponding to the discharged amount of water above the tubular body 19 is lowered. Can give flow. The suspended water, which has passed through the floc blanket layer and trapped and removed flocs (suspended substances), overflows into the trough 7 as treated water and is taken out as treated water through the treated water pipe 18.

Although the flock blanket layer will gradually increase in thickness as the above-described treatment is continued, the inner cylinder 24 is inserted into the tubular body 19 to constantly discharge water from the communication pipe 23. Therefore, as described above, a downward flow of the amount of water equivalent to the water discharged from the communication pipe 23 is generated in the tubular body 19 as indicated by the dotted arrow line, and thus the downward flow causes the downward flow of the upper surface in the flock blanket layer. Excessive flock overflows the upper end of the tubular body 19 and descends inside the tubular body 19 and forcibly flows down into the tubular body 19 (flock concentration chamber 12).
It is possible to increase the sedimentation velocity of the flocs within 12, and to make the interface of the floc blanket layer more constant.

This makes it possible to increase the rate of increase of flocs in the flock blanket layer, and thus to increase the rising linear velocity of the treated water.

Note that the flocs overflowing into the tubular body 19 descend in the tubular body 19 and are stored and concentrated in the lower part of the tubular body 19, and the excess concentrated flocs are sludge through the sludge extraction pipe 20. Periodically discharge out of the system.

The amount of raw water that gives the swirling flow to the flock blanket layer is 0.2 ~ 0.8 m / as the flow velocity at the raw water inlet.
It is desirable to set to sec. If the amount of raw water is less than 0.2 m / sec, the swirling velocity will be small and the floc concentration in the floc blanket layer cannot be made uniform.
If the amount of raw water is more than / sec, the swirling flow velocity becomes too high, and the flocs in the flock blanket layer may be destroyed or miniaturized. When treating more than the amount of raw water to give a swirling flow,
It is advisable that the excess raw water is jetted in a direction in which the swirl flow is not provided, usually downward, through a raw water pipe separately provided below the raw water pipe for providing the swirl flow.

<Example> An example will be described below in order to further clarify the effect of the device of the present invention.

[Example-1] In the apparatus of the present invention shown in Fig. 1, 40 mg / l of PAC (10% solution of polyaluminum chloride) was injected into raw water having a suspended substance concentration of 100 mg / l in which kaolin was suspended, and was inline After rapid mixing with a mixer, inject 1.1 mg / l of polyacrylic amide polymer flocculant and immediately height 3500 mm (height 2000 mm from bottom plate 10 to upper end of tubular body 19, height 2500 m of concentrating chamber 12)
m), and led to tank 2 having an inner diameter of 1000 mm. The inner diameter of the tubular body 19 was 500 mm. 0.5m from the raw water inlet 14 that blows the raw water in the direction that gives the swirling flow to the flock blanket layer.
Raw water was supplied at a flow rate of / sec.

At this time, the inner cylinder 24 having a lower end with an inner diameter of 300 mm opened and a closed upper end is inserted into the tubular body 19 (insertion depth 500 m.
m), one end of the communication pipe 23 is connected to the upper end of the inner cylinder 24, and the other end is positioned below the water surface of the tank 2 so that the communication pipe 23
By causing a part of the treated water to overflow due to the head difference from the above, an upward flow of 20 m / H was applied to the inner cylinder 24. As a result, it was possible to treat the raw water at an ascending linear velocity of 20 m / H, and the concentration of suspended solids in the treated water was 0.5 mg / l or less, which was an excellent result.

[Example-2] Raw water was treated under the same conditions as in Example-1 except that 1.0 m / sec of raw water was supplied from the raw water inlet 14 that blows the raw water in a direction to give a swirling flow to the floc blanket layer. As a result, the swirling flow velocity of the floc blanket layer was higher than that in Example-1, a slight amount of floc carryover occurred, and the concentration of suspended substances in the treated water was 1 to 2 mg / l.

[Example-3] Raw water was treated under the same conditions as in Example-1 except that 0.1 m / sec of raw water was supplied from the raw water inlet 14 that blows the raw water in a direction to give a swirling flow to the floc blanket layer. As a result, a part that does not fluidize is generated in a part of the floc blanket layer, the floc is partially wound up due to the channeling phenomenon, and the concentration of suspended matter in the treated water is 1 to 2 m.
It became g / l.

From the above results, it is understood that better treated water can be obtained by giving a proper swirling flow to the flock blanket layer.

<Effects of the Invention> As described above, the device of the present invention blows out at least a part of raw water at the raw water inlet in a direction in which a swirl flow is generated in the lower part of the flock blanket layer in the precipitation chamber, and the outside of the cylindrical body. In addition, by giving a uniform swirl flow to the donut-shaped portion inside the tank, it is possible to surely agglomerate the suspended matter in the raw water and form flocs, and to make the flocs concentration of the flocks blanket layer uniform. In addition, when the other part of the raw water flows in from below the swirl flow position, the swirl flow can be made to act as a water flow barrier against the upward flow from below, and the swirling flow can partially act due to the channeling phenomenon of the upward flow. Carryover of various flocs can be prevented in advance, and the uniform floc concentration in the flock blanket layer can provide a large ascending linear flow rate, which enables high-speed coagulation-sedimentation treatment. Further, the inner cylinder is inserted into the cylindrical body to give an upward flow to the inner cylinder, and a downward flow having a water amount corresponding to the amount of water of the upward flow is positively given to the cylindrical body. The sedimentation velocity can be increased, and the interface of the flock blanket layer can be made more constant, whereby the rising linear velocity of the treated water can be increased.

As described above, the device of the present invention has a simple structure having no special power part or mechanical part, and is highly useful as a high-speed coagulation-sedimentation processing device that is easy to maintain and consumes less energy.

[Brief description of drawings]

1 and 2 both relate to a floc blanket type coagulating sedimentation device of the present invention. FIG. 1 is a partially cutaway perspective explanatory view showing an example of an embodiment thereof, and FIG. 2 is a cross section of FIG. All of the surface explanatory views, FIG. 3 and FIG. 4 are longitudinal sectional explanatory views showing a conventional floc blanket type coagulating sedimentation device. 1 ... Raw water pipe, 2 ... Tank 3 ... Blocking cylinder, 4 ... Driver 5 ... Stirring blade 6 ... Flock blanket layer 7 ... Trough, 8 ... Coagulation chamber 9 ... Blowoff pipe, 10 …… Bottom plate 11 …… Settling chamber, 12 …… Floc concentrating chamber 13 …… Raw water piping, 14 …… Raw water inlet 18 …… Treatment water pipe, 19 …… Cylinder 20 …… Sludge extraction pipe 23 …… Communication Pipe, 24 …… Inner cylinder 25 …… Outflow pipe

Claims (2)

[Claims] 1. A tubular body having an open upper end and a closed lower end is erected in the center of the tank, and a raw water inlet is provided around the lower side of the tubular body, and the opening of the tubular body is provided. At least one of the raw water inlets is provided in a floc blanket type coagulating sedimentation apparatus in which a treated water outlet is provided above, a precipitation chamber having a flock blanket layer on the outside of the tubular body and a floc concentrating chamber on the inside of the tubular body. Part of the raw water is blown out in a direction that causes a swirl flow in the lower part of the flock blanket layer in the settling chamber to give a swirl flow to the flock blanket layer, and an inner cylinder with a lower end opened from the opening of the tubular body. Insert one end of the communication pipe to the upper end of the inner cylinder, and position the other end opening of the communication pipe below the water surface formed in the tank. Inner than tube Floc blanket type flocculator device characterized by providing a tubular body to the downward flow by discharging the water at all times. 2. The amount of raw water blown out in the direction in which a swirling flow is generated in the lower part of the flock blanket layer is 0.2 to 0.8 m / se.
The floc blanket type coagulation-sedimentation device according to claim 1, wherein the flocculation is c.