JP4181972B2 - Coagulation sedimentation processing equipment - Google Patents

Description

  The present invention relates to a coagulation sedimentation treatment apparatus, and more specifically, promotes sedimentation of flocs by adding a flocculant to raw water and mixing a sedimentation promoting material such as fine sand to form a floc having a large sedimentation rate, The present invention relates to a coagulation sedimentation processing apparatus that can rapidly precipitate and separate suspended components in raw water.

  As an apparatus for precipitating and separating suspended components (SS) in the raw water, a flocculant and a sedimentation accelerator such as fine sand are added and mixed in the raw water, and flocs with the fine sand as the core are formed and aggregated. There is known a high-speed coagulation sedimentation processing apparatus in which flocs are increased in weight to increase the sedimentation speed so that the sediment separation process can be performed in an extremely short time (see, for example, Patent Document 1).

  Such a coagulation sedimentation processing apparatus includes floc forming means for forming flocs by adding and mixing flocculant and fine sand to raw water, and floc separating means for precipitating and separating flocs generated by the floc forming means. And a fine sand separating means for separating the fine sand from the sediment separated by the floc separating means and circulating it to the floc forming means, and circulating the insoluble fine sand as a settling accelerator in the system. I am trying to use it.

  As the fine sand separation means, a cyclone that separates both the sludge and the fine sand in the floc is generally used, but in order to separate the sludge and the fine sand by the cyclone, the floc is separated at high speed. Need to be introduced to the cyclone. For this reason, there is a problem that not only a large-capacity pump is required to introduce the floc into the cyclone at a high speed, but also the flake containing fine sand passes through the pipe at a high speed and the pipe is worn. For this reason, not only the equipment cost and the power cost are increased, but also the maintenance cost required for maintenance of the pump and the piping is increased. Furthermore, in order to prevent clogging of the cyclone, a fine or fine screen must be installed in the inflow portion of the raw water to remove fine impurities.

In addition, as a means for separating fine sand without using a cyclone, a floc is introduced into a separation tank equipped with a stirrer, and the floc is crushed by the stirrer and separated into sludge and fine sand. Separation means has been proposed in which sand is extracted and circulated, and sludge is overflowed and extracted from the upper part of the separation tank (see, for example, Patent Document 2).
Japanese Patent No. 2634230 JP 2000-325704 A

  However, in the separation means described in Patent Document 2, since the inside of the separation tank is stirred at high speed by the stirrer, the fine sand separated from the floc overflows from the upper part of the separation tank together with the sludge. It sometimes leaked out of the system. For this reason, it will be necessary to replenish fine sand frequently. In addition, flocs that are not sufficiently crushed settle out to the bottom of the separation tank and are extracted and circulated to the floc forming means, which may increase the processing load.

  Therefore, the present invention can reliably separate the fine sand, can prevent the fine sand from flowing out of the system and circulate almost the entire amount of the fine sand, greatly increasing the equipment cost and maintenance cost. It aims at providing the coagulation sedimentation processing apparatus which can be reduced.

  In order to achieve the above object, the coagulation sedimentation processing apparatus of the present invention comprises a floc forming means for forming a sedimentation promoting material-containing floc by adding and mixing a sedimentation promoting material comprising a flocculant and insoluble fine particles to raw water, and the floc A floc separating means for precipitating and separating the sedimentation promoting material-containing floc produced by the forming means to obtain treated water; and separating the sedimentation promoting material from the sedimentation promoting material-containing floc precipitated and separated by the floc separating means A floc crushing means for crushing the sedimentation promoting material-containing floc and separating it into sludge and a sedimentation promoting material. A sedimentation promoting agent for separating and separating a sedimentation promoting material from a mixture comprising a floc crushing portion provided with a sludge and a sedimentation promoting material separated by the floc crushing portion The material sedimentation separation unit, the sedimentation promotion material extraction path for extracting and supplying the sedimentation promotion material precipitated and separated in the sedimentation promotion material sedimentation separation unit and circulating to the floc forming means, and the top of the sedimentation promotion material precipitation separation unit It is characterized by having a sludge extraction route for extracting sludge.

  Furthermore, the coagulation sedimentation processing apparatus of the present invention is provided with a circulation path for extracting a part of the mixture from the sedimentation promoting material sedimentation separation unit and circulating it to the floc crushing unit, A draft tube provided in the mixture in the central portion of the tank, and a downward flow generator for generating a downward flow on the inner periphery of the draft tube and generating an upward flow on the outer periphery of the draft tube It is characterized by that.

  According to the coagulation sedimentation processing apparatus of the present invention, the floc extracted from the floc separating means is crushed by the floc crushing section equipped with the floc crushing means, so that it is not necessary to transfer the floc at a high speed, and a large capacity pump is unnecessary. As a result, there is almost no wear on the piping. Further, since the separation and collection of the fine sand is performed in the sedimentation promoting material settling part, it is possible to reliably separate the sludge and the fine sand, and it is possible to circulate substantially the entire fine sand. Accordingly, it is possible to reduce the facility cost and the power cost, and it is almost unnecessary to replenish the fine sand, and the replacement time of the piping and the like is greatly extended, so that the maintenance cost can be greatly reduced.

  FIG. 1 is a system diagram of a coagulation sedimentation processing apparatus showing an embodiment of the present invention. First, the coagulation sedimentation processing apparatus includes a floc forming means 10 for agglomerating and forming flocs with good sedimentation by adding and mixing fine sand as a settling accelerator composed of an aggregating agent and insoluble fine particles to raw water, and the floc formation. The floc separating means 20 for separating and separating the floc containing the sedimentation promoting material produced by the means 10, and the floc forming means 10 by separating fine sand from the precipitate (floc) precipitated and separated by the floc separating means 20 And sedimentation promoting material separating means 30 to be circulated.

  The floc forming means 10 includes a raw water inflow path 11, an inorganic flocculant addition path 12, and a first agitation tank (rapid agitation tank) 13 provided with a stirrer 13M, a polymer flocculant addition path 14, a fine sand addition path 15 and It is formed of a second stirring tank (injection stirring tank) 16 provided with a stirrer 16M and a flock forming tank 17 provided with a stirrer 17M. The first stirring tank 13 and the second stirring tank 16 communicate with each other at the upper part of the partition wall 18, and the second stirring tank 16 and the flock formation tank 17 communicate with each other at the lower part of the partition wall 19.

  The floc separating means 20 has a sediment extraction path 23 for extracting sediment (precipitation accelerating material-containing floc, hereinafter referred to as floc) from a sludge pit 21 provided at the bottom of the tank via a sediment transport pump 22. A sedimentation tank 26 having a treated water outflow path 25 for discharging treated water through a water collecting tank 24 provided at the upper part, and flocs settled on the bottom of the tank are scraped into the sludge pit 21 at the bottom of the tank. A sludge scraper 27 for feeding is provided. In addition, an inclined plate 28 for promoting a floc separation effect is provided below the catchment basin 24, and a partition wall 29 that communicates with the floc formation tank 17 at one side on one side of the sedimentation tank 26. Is provided.

  The sedimentation promoting material separating means 30 includes a floc crushing tank 31 as a flock crushing section that crushes the floc extracted in the sediment extraction path 23 and separates it into fine sand and sludge, and the fine particles separated in the flock crushing tank 31. A fine sand settling tank 32 as a settling promoting material settling part for precipitating fine sand from a mixture containing sand and sludge, and the fine sand settling at the bottom of the fine sand settling tank 32 and extracting the fine sand 15, a sedimentation promoting material extraction path 33 that is circulated and supplied to 15, a sludge extraction path 34 that extracts the sludge rising above the fine sand settling tank 32, and fine sand and sludge from the flock crushing tank 31 to the fine sand settling tank 32. A mixture supply path 35 for supplying a mixture containing the mixture, and a mixture circulation in which a part of the mixture in the fine sand settling tank 32 is circulated from the fine sand settling tank 32 to the flock crushing tank 31 by the circulation pump 36. And a route 37.

  The flock crushing tank 31 is provided with a crusher 38 provided with a cutter for crushing flocks as a flock crushing means. By operating this crusher 38, the flock is crushed and fine sand and sludge are obtained. And to separate.

  Further, inside the fine sand settling tank 32, a draft tube 41 provided in the mixture in the center of the tank, and a downward flow is generated on the inner periphery of the draft tube 41, and the outer periphery of the draft tube 41 rises. A downward flow generator 42 such as a screw for generating a flow and an upper partition wall 43 that divides the tank upper portion into the inside and outside are provided, and an upper tank wall 32a of a portion where the upper partition wall 43 is provided, The sludge ascending portion 44 having a large area is formed between the upper partition wall 43 and the upper tank wall 32a.

  The raw water flowing into the first agitation tank 13 from the raw water inflow path 11 is mixed with the inorganic flocculant supplied from the inorganic flocculant addition path 12, then passes over the partition wall 18 and flows into the second agitation tank 16. . In the second agitation tank 16, after the polymer flocculant supplied from the polymer flocculant addition path 14 and the fine sand introduced from the fine sand addition path 15 are mixed, the floc formation tank passes below the partition wall 19. When the suspended components in the raw water agglomerate in the floc forming tank 17, the fine sand which is a settling accelerator is adsorbed to form an agglomerated floc having a high sedimentation property.

  The raw water containing the floc flows into the settling tank 26 through the upper part of the partition wall 29, the floc settles and separates at the bottom of the tank, and the treated water is extracted from the treated water outflow path 25, and the floc that has settled at the bottom of the tank. Is extracted from the sludge pit 21 to the sediment extraction path 23 and sent to the floc crushing tank 31.

  The floc that has flowed into the floc crushing tank 31 is crushed by a cutter of a crusher 38 that rotates at high speed, and becomes a mixture in which fine sand and sludge are separated. This mixture is supplied to the fine sand settling tank 32 through the mixture supply path 35. At this time, in the mixture supplied to the fine sand settling tank 32, fine sand and sludge separated in the flock crushing tank 31 and uncrushed flock existed, and their specific gravity is fine. Sand, frock and sludge are decreasing in this order.

  The downflow generator 42 generates a flow rate such that fine sand having the largest specific gravity settles in the mixture rising outside the draft tube 41 and flocs and sludge rise. Therefore, the fine sand is settled toward the bottom of the tank while the mixture ascends outside the draft tube 41. The fine sand that has settled at the bottom of the tank is extracted to the settling accelerator extraction path 33 and circulated and supplied to the second stirring tank 16 through the fine sand addition path 15. The conveyance of the fine sand from the settling accelerator extraction path 33 to the fine sand addition path 15 can be arbitrarily selected according to the positional relationship between them, for example, using a screw type conveyor or the like. Can do.

  At this time, by storing the fine sand in the equipment used as the conveying means, for example, the screw conveyor, the fine sand is collected and stored in the screw conveyor after the coagulation sedimentation operation is completed. Therefore, by operating the screw conveyor at a predetermined speed at the start of the next coagulation sedimentation operation, it is possible to supply a fixed amount of fine sand to the second agitation tank 16, so that the operation can be resumed in a short time. It can be carried out.

  Further, the sludge ascending section 44 has the highest specific gravity according to the mixture inflow amount from the mixture supply path 35, the fine sand extraction amount from the settling accelerator extraction path 33, and the mixture circulation quantity in the mixture circulation path 37. The water area is set so that the flow rate is such that small sludge rises but uncrushed flocs sink. Therefore, when sludge and floc flow from the lower end of the upper partition wall 43 into the sludge ascending portion 44, the sludge rises along with the upward flow of the sludge ascending portion 44, overflows the upper portion of the tank, and is extracted from the sludge extraction path 34. The flocs are returned to the flow of the mixture rising outside the draft tube 41 without rising the sludge raising portion 44.

  As described above, the flow rate of the upward flow in the fine sand settling tank 32 is set so that the fine sand is settled and the floc and sludge rise, and the upper partition wall 43 where the sludge rises and the floc settles. By separating the area from the outer area, fine sand and floc are not accompanied by the sludge extracted from the sludge extraction passage 34, so that the fine sand can be reliably separated and floc formed. It is almost unnecessary to replenish the means 10 with fine sand.

  Furthermore, since the floc and mixture containing fine sand such as the sediment extraction channel 23 and the mixture supply channel 35 do not require a high flow rate like a cyclone, the capacity of the sediment transport pump 22 and the like can be reduced. As a result, the pipes and pump parts that form the sediment extraction path 23 are hardly worn. In addition, even if fine contaminants invade, there is almost no effect on the separation of fine sand, so the secondary effect of installing a screen to remove coarse contaminants at the inflow of raw water Can also be obtained.

  Further, a part of the mixture in the fine sand settling tank 32 is extracted from the inner part of the upper partition wall 43 to the mixture circulation path 37 at the upper part of the fine sand settling tank 32 and returned to the floc crushing tank 31 to be stored in the flocs. The crushing process is performed again. The mixture circulated from the fine sand settling tank 32 to the flock crushing tank 31 is mainly sludge and flocks depending on the position of the mixture circulation path 37, and the flock is in an uncrushed state in the flock crushing tank 31. The floc that has flowed into the fine sand settling tank 32 and the floc that has been re-agglomerated inside the fine sand settling tank 32 are included.

  In this way, by circulating a part of the mixture in the fine sand settling tank 32 to the flock crushing tank 31, the floc crushing tank 31 cannot be sufficiently crushed or reaggregated inside the fine sand settling tank 32. The flocs can be reliably separated into sludge and fine sand, and the separation efficiency of fine sand can be greatly increased. However, the circulation of the mixture by the mixture circulation path 37 can be omitted if the crushed floc and the re-aggregated floc can be crushed by the downflow generator 42.

  If there is no problem even if a small amount of floc is returned to the floc forming means 10 together with the fine sand, only the sludge increases the flow rate of the upward flow in the fine sand settling tank 32, and the floc and fine sand are settled. By setting the conditions, the mixture circulation path 37 can be omitted.

  Further, by providing the draft tube 41 and the downward flow generator 42 to form the upward flow as described above, the fine sand can be reliably separated in a short time. On the other hand, the upward flow in the fine sand settling tank 32 can also be formed by supplying the mixture from the mixture supply path 35 directly downward into the draft tube 41. In this case, the downward flow generator 42 is omitted. can do. Further, an upflow can also be formed by supplying the mixture from the mixture supply path 35 from the lower part of the tank without providing the draft tube 41. In this case, the draft tube 41 and the downflow generator 42 are omitted. You can also

  FIG. 2 is a cross-sectional view showing another embodiment of the sedimentation promoting material sedimentation separation unit. In addition, in the following description, the same code | symbol is attached | subjected to the component same as the component in the sedimentation promoting material sedimentation separation part shown by the said form example, and detailed description is abbreviate | omitted.

  The sedimentation promoting material sedimentation separation part shown in this embodiment is provided with a downflow generator 52 and a crusher 53 such as a cutter inside a draft tube 51 provided in the fine sand sedimentation tank 32, and a flock crushing part and sedimentation promotion. The material precipitation separation part is integrated. Thus, by integrating the floc crushing part and the sedimentation promoting material precipitation separating part, the installation area can be reduced and the equipment cost can be reduced. In addition, the integrated sedimentation accelerator sediment separation portion and the floc crushing tank 31 may be installed to omit the mixture circulation path 37.

  The coagulation sedimentation treatment apparatus of the present invention can rapidly precipitate and separate suspended components in raw water while reducing facility costs and maintenance costs, and can therefore be used as a suspension component removal device in various water treatment facilities.

It is a systematic diagram of the coagulation sedimentation processing device which shows one example of the present invention. It is sectional drawing which shows the other example of a form of a sedimentation promoter sedimentation part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Flock formation means, 11 ... Raw water inflow path, 12 ... Inorganic flocculant addition path, 13 ... 1st stirring tank (rapid stirring tank), 14 ... Polymer flocculant addition path, 15 ... Fine sand addition path, 16 ... Second stirring tank (injection stirring tank), 17 ... flock formation tank, 18, 19 ... partition wall, 20 ... flock separating means, 21 ... sludge pit, 22 ... sediment transport pump, 23 ... sediment extraction path, 24 ... collection Water tank, 25 ... treated water outflow route, 26 ... sedimentation tank, 27 ... sludge scraper, 28 ... inclined plate, 29 ... partition wall, 30 ... sedimentation accelerator separating means, 31 ... floc crushing tank, 32 ... fine sand sedimentation Tank, 33 ... Settling accelerating material extraction path, 34 ... Sludge extraction path, 35 ... Mixture supply path, 36 ... Circulation pump, 37 ... Mixture circulation path, 38 ... Crusher, 41 ... Draft tube, 42 ... Downflow generation Machine, 43 ... Upper partition, 44 ... Sludge Temperature portion, 51 ... draft tube, 52 ... downflow generator, 53 ... crusher

Claims (3)

  A floc forming means for forming a flocculant containing flocculant and insoluble fine particles into raw water to form a floc forming material-containing floc, and processing by precipitating and separating the flocculant-containing floc generated by the floc forming means Floc separation means for obtaining water, and a settling accelerator separating means for separating the settling accelerator from the settling accelerator-containing floc precipitated and separated by the floc separating means and circulating it to the floc forming means In the processing apparatus, the settling promoting material separating means includes a flock crushing section provided with a flock crushing means for crushing the settling promoting material-containing floc and separating it into sludge and a settling promoting material, and sludge separated by the floc crushing section. The sedimentation promoting material is separated from the mixture containing the sedimentation promoting material and the sedimentation promoting material is separated by precipitation. It comprises a sedimentation facilitating material extraction path for extracting the sedimentation facilitating material and supplying it to the floc forming means, and a sludge extraction path for extracting the sludge rising above the sedimentation facilitating material sedimentation section. Coagulation sedimentation processing equipment.   The coagulation sedimentation processing apparatus according to claim 1, further comprising a circulation path for extracting a part of the mixture from the sedimentation promoting material sedimentation separation unit and circulating it to the floc crushing unit.   The sedimentation accelerator sediment separator is a draft tube provided in the mixture in the center of the tank, and generates a downward flow on the inner periphery of the draft tube and an upward flow on the outer periphery of the draft tube. The coagulation sedimentation processing apparatus according to claim 1, further comprising a downflow generator.

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