JPH0215275B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for coagulating and clarifying suspended water in water supplies, industrial waterways, sewers, civil engineering drainage, human waste treatment, industrial wastewater treatment, etc. There are two types of suspended matter in turbid water: inorganic matter and organic matter (algae, etc.). Inorganic matter has a high density and is easy to settle, but organic matter has a low density and is difficult to settle. , rather, it has the property of easily surfacing. In normal river water, inorganic turbidity makes up the majority, while in lake water and eutrophic reservoir water, organic turbidity often occupies the majority. Even in river water, turbidity may change seasonally due to drought periods, torrential rains, etc. That is, during dry periods, organic turbidity is mixed or accounts for most of the turbidity, and when turbidity increases due to torrential rain, etc., the turbidity is mostly inorganic. A coagulation-sedimentation device is generally used as a coagulation and turbidity removal device, but when organic turbidity is mixed, a phenomenon that difficult-to-settle flocs often flows out into the treated water, and it is difficult to use the rapid filtration device after the rapid filtration device When installed, this outflow floc causes the filtration device to become clogged more quickly. Furthermore, conventional coagulation-sedimentation equipment requires about 4 hours of residence time, including mixing of chemicals and formation of flocs. In view of this, the present invention has been developed to treat water of the same quality as conventional coagulation and sedimentation equipment, in a time three to one fraction of the time, and to process raw water from low turbidity to high turbidity. Furthermore, the aim was to stably remove turbidity regardless of whether the turbidity was organic or inorganic, by injecting a flocculant into the suspended water and stirring it rapidly, then arranging a large number of perforated plates. The flocs are allowed to flow down the floc formation tank to form the desired flocs, and then the flocs are rectified and settled to perform primary clarification, and the supernatant water is led to the flotation tank where the scum is floated and separated under pressure. The first invention is characterized in that the secondary clarification of turbidity is carried out, and the mixing tank is characterized in that a flocculant is injected into turbid water and rapidly stirred,
A perforated plate floc formation tank in which a large number of perforated plates are arranged is provided adjacent to the tank, and a rectifying table descending tank is installed in the tank to allow the flocs to settle and perform primary clarification, and the supernatant water of this rectifying settling tank is guided to float A separation tank is provided, and the flotation separation tank is equipped with a reduced pressure bubble generator to help float the scum and a sludge scraping device to perform secondary clarification by scraping and scraping the floating scum. This invention consists of a second invention. The present invention will be explained below based on illustrated embodiments. Suspended water (raw water) such as sewage, industrial, industrial, and civil engineering wastewater is supplied to a mixing tank 1 and rapidly stirred with a chemical such as a coagulant injected into the tank by a rapid stirring device 2. Reference numeral 3 denotes a partition wall provided between this mixing tank 1 and the next adjacent floc forming tank 4. The lower part of the partition wall is opened, and the flocculant and turbid water stirred in the mixing tank 1 are passed through the opening in the lower part of this partition wall. The flocculation tank 4 is supplied with more fluid. This floc formation tank 4 has a large number of perforated plates 5 arranged in a direction that prevents the flow of turbid water.
are vertically arranged at arbitrary intervals, and when flowing down the group of perforated plates 5, the suspended solids in the turbid water are flocculated by the action of the flocculant, and the flocculated particles grow while flowing down each of the perforated plates. Flows down the hole. In this case, the size and shape of the perforated plate are arbitrary. For example, in order to facilitate flocculation, the pore diameter on the upstream side near the mixing tank is small, and the pore diameter on the downstream side near the rectifying settling tank is large. Or, perforated plates with the same hole diameter may be arranged at unequal intervals on the upstream and downstream sides of the floc formation tank, or the perforation positions on each plate may be different. The holes may be arranged as shown in FIG. A rectifying sedimentation tank 6 is adjacent to the downstream side of the flocculation tank 4 in which a large number of perforated plates are arranged, and the suspended matter in the turbid water is supplied from the flocculation tank 4 to the rectification sedimentation tank 6 as flocculation particles. Do it like this. A sludge pipe 7 is installed at the bottom of this rectification settling tank to discharge the settled flocculated turbidity out of the tank, and when the settled sludge reaches a certain amount, it is discharged periodically or selectively. . In this case, the bottom of the tank should be shaped like a ship's bottom or some other shape to facilitate the collection of settled flocculated suspended solids. In this rectified sedimentation tank, the main material is inorganic suspended matter that has high turbidity and is easy to settle. The flocculated turbidity is sedimented in this rectifying sedimentation tank and primary clarification is performed, but organic turbidity with low turbidity or unsedimented turbidity is transferred to the upper clear turbid water of the sedimentation tank. is supplied to the flotation separation tank 8. The supernatant turbid water supplied to the flotation tank 8 is supplied within a partition plate 9 provided on the upstream side of the flotation tank. The lower part of this partition plate 9 is opened, and the air is guided into the flotation separation tank through this opening, but in this case, a vacuum bubble generator 10 is provided below the partition plate of the tank, and a decompression bubble generator 10 is installed outside the tank. Pressurized water is supplied from a pressurized water tank 11. This pressurized water storage tank 11 is supplied with treated water or clean water from which suspended solids (scum) have been removed in a flotation separation tank, and a pressurized pump 1
2, pressurized air is supplied from the compressor 13 to the tank 11, the air is dissolved under pressure, and this is ejected into the separation tank from the vacuum bubble device 10 through the pressurized water supply pipe 14. When the pressure is reduced, the air dissolved in the pressurized water becomes bubbles due to the reduced pressure and floats up inside the separation tank. At this time, the low turbidity and organic suspended matter contained in the supernatant turbid water rises to the surface and becomes suspended on the liquid surface above the tank, forming scum. This floating scum is scraped up by a sludge scraping device 15 installed at the top of the flotation separation tank and discharged to the outside of the tank, and the treated water from which the suspended matter has been separated is drained via a strainer 16. It is. Example

[Table] The treatment conditions of the above table were set to treat turbid water, and the flow was sequentially flowed down from the mixing tank to the flocculation tank, rectification sedimentation tank, and flotation separation tank. As a result, the following effects were obtained.

[Table] Therefore, when using the present invention, turbid water can be treated in an extremely short time compared to conventional methods, and it can be used to treat turbid water from low turbidity raw water to high turbidity raw water, regardless of the quality of the turbidity, organic or organic. It has advantages such as stable turbidity removal.

[Brief explanation of drawings]

The drawing is a schematic diagram showing the apparatus for coagulating and removing turbidity of turbid water according to the present invention. 1... Mixing tank, 2... Rapid stirring device, 3, 9...
... Partition wall, 4 ... Block forming tank, 5 ... Perforated plate,
6... Rectification sedimentation tank, 7... Sludge removal pipe, 8... Flotation separation tank, 10... Decompression bubble generator, 11... Pressurized water tank, 12... Pressurized pump, 13... Compressor, 14 ... Pressurized water supply pipe, 15 ... Sludge scraping device, 16 ... Strainer.

Claims (1)

[Claims] 1. After injecting a flocculant into suspended water and stirring rapidly, the flocculant is allowed to flow down a floc formation tank in which a large number of perforated plates are arranged to form a desired floc, and then the flocculant is rectified. It is characterized in that primary clarification is performed by sedimentation, and the supernatant water is led to a flotation separation tank, where the scum is floated and separated under pressure to perform secondary clarification of the turbidity. Coagulation and clarification method for turbid water. 2 Rectification sedimentation in which a perforated plate floc formation tank in which a large number of perforated plates are arranged is adjacent to a mixing tank in which a flocculant is injected into turbid water and rapidly stirred, and the floc is settled in the tank to perform primary clarification. In addition to providing a tank, a flotation separation tank is installed to guide the supernatant water of this rectification sedimentation tank, and a depressurized bubble generator to help float the scum and a scraping scraper for the floating scum are installed in the flotation separation tank. A turbid water coagulation clarification device comprising a sludge scraping device that performs secondary clarification.