JP6292612B2 - River water clarification method - Google Patents

Description

The present invention relates to a clarification method for obtaining clean water using river water.

  Conventionally, various water supply systems have been proposed to obtain clean water from river water and dam / lake water. For example, water discharged from a dam is taken, introduced into a sand basin, sand and coarse dust flowing there are removed, and then introduced into a receiving well through a water tunnel. The landing well adjusts the amount and level of raw water (river water), adds a chlorinating agent (sodium hypochlorite) for disinfection, and injects caustic soda for pH adjustment. The raw water thus adjusted is then introduced into the chemical mixing pond, where aggregating agent such as polyaluminum chloride is added and agitated in order to agglomerate the pollutants in the raw water. The raw water to which the flocculant has been added is then introduced into the floc formation pond, where the raw water is gently flowed up and down to stir to coagulate the pollutant and to flock.

  The raw water treated in the floc formation pond is introduced into the inclined plate sedimentation basin, where the floc is settled and the supernatant water is sent to the next rapid filtration pond. The rapid filtration pond is provided with a sand and gravel filtration layer. By passing this filtration layer, dirt and the like that have not been removed in the inclined plate sedimentation basin are removed. If necessary, the clarified water (clean water) processed in the rapid filtration pond is injected with a chlorine agent or the like and introduced into the water purification pond. The water from the clean pond is sent to the city and town reservoirs through the water pipe.

  On the other hand, the sludge settled in the sloping plate sedimentation pond is sent to the waste mud pond and sent from here to the concentration tank, where the sludge is concentrated. The concentrated sludge is sent to a sun drying bed or dehydrator to be dried, and the water is discharged into the river.

  In addition, in the water supply system, as an improvement of the inclined plate sedimentation pond, a sheet-like membrane is formed in the vicinity of the raw water inflow section in a sedimentation separation device that may cause a convection phenomenon due to a difference in water temperature between the pond water and the inflowing raw water. A sedimentation and separation apparatus is proposed, which is arranged in series so as to cross at right angles to the water flow direction of the raw water, and is provided with a space behind the series of sheet-like membranes so as to extend multiple strips below the water surface. (Patent Document 1).

  Patent Document 1 JP 2013-85998 A

However, in the case of the inclined plate sedimentation basin, the inclined plate is good when the turbidity is low, but when the raw water becomes high turbidity due to rainfall or landslide, it is difficult to settle the solid-liquid separation.
That is, when the turbidity of river water becomes high due to rain or the like, sedimentation in the inclined plate goes to the lower layer due to the pressure on the inclined plate wall surface, so that the turbidity concentration increases and the sedimentation rate becomes slow. This is due to the fact that the sedimentation condition that should be solid-liquid separated changes and the desired sedimentation area and sedimentation speed cannot be obtained. Furthermore, if the interference sedimentation state continues due to the particles that have settled from the upper stage of the inclined plate, it stagnates, and the gap between the connected inclined plates closes, increasing the frequency of washing of the subsequent filter and pausing the water supply system. As a result, the supply of clean water became impossible. In order to solve this problem, the technology of Patent Document 1 was developed, and it was possible to prevent the clogging of the inclined plate even in high concentration turbidity river water, but the sludge amount in the inclined plate settling basin increased. As a result, the treatment of the concentrated layer could not be handled, and as a result, the water supply system had to be stopped.
Therefore, the present inventor has completed the present invention as a result of conducting various studies on a method for continuously operating the water supply system even in the case of river water with high turbidity using the existing water supply system.

That is, in the present invention, after adding flocculant in the chemical mixing pond to the river water, it is introduced into the floc-forming pond to flock the pollutants, and then the water is inclined into the sloping plate sedimentation basin by the water-flow inclined plate. The sludge / blanket part having a contact / filtration function with a high concentration is installed, and the sludge settled in the inclined plate sedimentation basin is introduced into the inclined plate sedimentation basin provided with the inclined plate downstream thereof. After introducing the sludge water from the bottom into the sludge pond by a sand pipe and introducing this sludge water into a concentrating tank that has been extended in a circular shape with a water flow inclined plate, the sludge is concentrated, and then a sun drying bed or dehydrator On the other hand, the supernatant water of the inclined plate sedimentation basin is introduced into a rapid filtration pond having a filtration layer, and the water that has passed through the filtration layer is introduced into the water purification pond.

According to the method of the present invention, by providing a sludge / blanket part with a water flow inclined plate in the inclined plate settling basin, the concentration becomes high in the preceding stage of the settling basin provided with the water flow inclined plate. Concentrate, thereby increasing water area, water area ordering and rectification, improving initial sedimentation concentration, forming multi-particle groups, preventing short circuit flow, reducing chemical injection volume, and reducing filter washing frequency Can do.
Further, by providing a water flow inclined plate in the concentration tank, initial sedimentation can be promoted and solid-liquid separation can be measured, so that a large amount of sludge can be treated.

As described above, the present invention solves the problems in the inclined plate sedimentation basin and the concentration tank at the same time, and can always operate without stopping the water supply system due to changes in turbidity of river water. The entity called pause can be resolved.

Front view showing an example of a water current inclined plate Top view of sloping plate sedimentation pond Longitudinal section of inclined plate sedimentation pond Top view of the concentration tank Longitudinal section of the concentration tank Flow chart showing the river water treatment method of the present invention

First, the water flow inclined plate used in the apparatus of the present invention will be described.
FIG. 1 is a front view in which water flow inclined plates 1 are stretched in series. The water flow inclined plate 1 has a flexible or rigid hanging plate 3 at the lower part of the float 2, and a weight 4 is provided at the lower end of the hanging plate 3 as necessary. The width of the hanging plate 3 is narrower than the width of the float 2, and by connecting the floats 2 in series, the water surface portion has no gap between the adjacent floats 2, and the water flow is stopped and returned to the surface. The reverse flow occurs. Since the underwater portion has a gap between the adjacent hanging plates 3, the raw water can easily pass therethrough.
Moreover, the water flow inclination board 1 fixes the support frame which suspends the drooping board 3 using steel materials, such as H-shaped steel, near the water surface part of the apparatus extended instead of the above-mentioned float 2, and adjoins this support frame. It is suspended in a desired shape with a gap between the hanging plates 3.
Examples of the flexible hanging plate 3 used in the present invention include a canvas sheet, a PVA tarpaulin sheet, an EVA tarpaulin sheet, a rubber tarpaulin sheet, and a net film. Moreover, as the rigid drooping board 3, resin boards, such as a vinyl chloride board and a polyethylene board, or metal boards, such as a stainless steel board and a titanium board, are fried.

FIG. 2 shows a plan view of the inclined plate sedimentation basin. The existing inclined plate on the floc formation pond side of the inclined plate settling basin is removed, and the water flow inclined plate 1 is further expanded in the shape. Fig. 2 shows the case where 6 square shapes are installed in the flow direction of river water. The number of square shapes should be selected as appropriate considering the turbidity of river water. Can do.
FIG. 3 is a sectional view of FIG.

Next, the concentration tank used in the method of the present invention will be described.
FIG. 4 shows a plan view of a concentration tank with a sludge scraper 5. As shown in the figure, a case is shown in which the water flow inclined plate 1 is multi-stretched in a hexagonal shape. And how many strips of the water flow inclined plate 1 should be extended may be appropriately selected depending on the concentration of sludge and the like. FIG. 5 is a schematic diagram of FIG.

Next, the river water clarification method of the present invention will be described with reference to FIG.
River water is introduced into the sand basin 7 from the intake weir 6 to remove sand and large debris flowing along with the river water. Thereafter, the water is introduced into the landing well 9 through the water conduit 8, where a chlorinating agent is added for disinfection and caustic soda is added for pH adjustment. River water treated in the landing well 9 is introduced into the chemical mixing basin 11 through the conduit 10. In the chemical mixing pond 11, a flocculant such as polyaluminum chloride is added while being stirred by the stirrer 12, and introduced into the floc forming pond 14 through the conduit 13. The flock formation pond 14 is provided with a partition wall 15 from above and below so that the river water is upstream and downstream. Here, the pollutant is flocked and becomes a lump that tends to settle. Next, the river water is introduced into the inclined plate sedimentation basin 16 and first passes through the sludge / blanket portion 17 provided with the water flow inclined plate 1 and then passes through the inclined plate 18 to collect the flock at the bottom of the inclined plate sedimentation basin 16. . Sludge collected in the inclined plate sedimentation basin 16 is introduced into the mud basin 20 through the sludge pipe 19. The sludge that has entered the sludge pond 20 is introduced into the concentration tank 23 through the conduit 22 in a state of being stirred and dispersed by the stirrer 21. In the concentrating tank 23, since the water flow inclined plate 1 is multi-stretched in a hexagonal shape from the water surface, initial sedimentation is promoted and suitable solid-liquid separation can be measured. The sludge water treated in the concentration tank 23 is introduced into the sun drying bed 25 through the conduit 24, the supernatant water is discharged into the river, and the concentrated sludge is naturally dried or dehydrated.

On the other hand, the supernatant water treated in the inclined plate sedimentation basin 16 is introduced into the rapid filtration basin 27 through the conduit 26, filtered through the filtration layer 28 made of sand and gravel, and then sent to the clean water basin 30 through the conduit 29. . The treated water from the water purification basin 30 is fed by a water pipe to a distribution reservoir in a municipality via a pressure-intensifying pump station and a water supply station. Water is then supplied from the distribution reservoir to each household.

DESCRIPTION OF SYMBOLS 1 ... Water flow inclination board 2 ... Float 3 ... Flexible or rigid hanging board 16 ... Inclination board sedimentation basin 22 ... Concentration tank

Claims (1)

After adding the flocculant in the chemical sedimentation pond to the river water, it is introduced into the floc formation pond to flock the pollutants, and then the water flow with a flexible or rigid drooping plate at the bottom of the float in the sloping plate sedimentation pond. The sludge blanket section divided into the shape by the inclined plate is installed, and the sludge settled in the inclined plate settling basin is introduced into the inclined plate settling basin provided with the inclined plate on the downstream side. And then introduced into a sludge pond by a sand drain pipe, and this sludge water is introduced into a concentration tank that is multi-stretched in a circular shape with the water flow inclined plate to concentrate the sludge, and then to a sun drying bed or dehydrator, On the other hand, the river water clarification method is characterized in that the supernatant water of the inclined plate sedimentation basin is introduced into a rapid filtration pond having a filtration tank, and the clean water that has passed through the filtration tank is introduced into the water purification pond.

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