JPH0138523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved coagulation treatment apparatus for coagulation and sedimentation treatment of suspensions (raw wastewater) and the like.

Coagulation-sedimentation treatment methods are generally used to clarify raw wastewater and separate suspended substances (particles) in wastewater, but the flocs produced by conventional coagulation-sedimentation methods have very loose bonds. Moreover, the aggregated flocs themselves have a particle size distribution of various sizes. Since the particles also contain small particles, the upward flow rate, that is, the separation speed, could only be maintained at a maximum of 2 m/h. If this separation speed is increased, the settling tank itself can be made smaller, but in the conventional method, the tank itself had to be large, and the installation area was large.

The present invention was made to eliminate the above-mentioned drawbacks, and by forming highly uniform, coarse, and dense flocs, the upward flow rate, that is, the separation speed, is increased, and the flocculation is compact and has excellent performance. The purpose of the present invention is to provide a sedimentation treatment device, in which a rotatable feed supply pipe is installed upright in a sedimentation tank, and the tip of the feed supply pipe is equipped with a blowout pipe having a plurality of blowout holes, Furthermore, a mechanism for supplying raw wastewater and sludge to the upper part of the feed supply pipe, a mechanism for supplying additives from at least two locations, the upper and lower parts of the feed supply pipe, a mechanism for mixing and stirring the feed in the feed supply pipe, The present invention is characterized by comprising a sludge scraping mechanism provided at the lower part of the sedimentation tank that rotates integrally with the feed supply pipe, and a sludge extraction means that operates in conjunction with an interface detector.

Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings.

1 is a settling tank, and the inside is divided into a clear layer A, a coagulated floc layer B, and a thickened sludge layer C. Reference numeral 2 denotes a feed supply pipe, which is installed vertically inside the sedimentation tank 1 and can be rotated by a drive unit 14, and a sludge scraper 5 is provided below the feed pipe. This feed supply pipe 2
Raw wastewater is sent from the inflow pump 6 into the interior, and various additives (inorganic flocculant, polymer flocculant, neutralizing agent) are sent to the upper part of the supply pipe 2 and, if necessary, the lower part by the chemical supply pump 7. etc.), and concentrated sludge returned by the return pump 8 or sludge obtained from a separate process. In addition, by injecting the additive not only into the upper part of the feed pipe 2 but also into the lower part or the coagulated floc layer, the desired floc strength and high level can be achieved with a small amount of additive (approximately 0.5 to 1 mg per amount of raw wastewater). A concentrated sludge is obtained,
It improves the dewaterability of sludge and is economically advantageous. The amount of sludge input is determined depending on the raw wastewater and sludge concentration, etc., but the ratio between raw wastewater and sludge amount
A ratio of 100:1 to 100:5 is desirable. Reference numeral 3 denotes a feed suspension blowing pipe, which is provided at the lower tip of the feed supply pipe 2 and has a plurality of blowing holes 9. Reference numeral 4 denotes a stirring blade, which is rotated by the stirring drive unit 10 within the feed supply pipe 2 to mix and stir the feed consisting of raw wastewater, sludge, and additives. As the stirring blades 4, any of paddle type, gate type, and pillow type can be used, but it is preferable to provide a large number of them. 11 is an interface detector, 12 is a sludge drawing pump, 13 is an overflow section, and 14 is a drive section for a feed supply pipe and a sludge scraper connected thereto.

Next, to describe the operation of this embodiment, when raw wastewater is supplied from the inflow pump 6, various additives are supplied from the chemical supply pump 7, and concentrated sludge is supplied from the return pump through the pipes into the feed supply pipe 2. These raw wastewater and additive sludge are stirred and mixed by the stirring blades 4 rotated by the stirring drive unit 10 to form a feed. This feed flows out from a plurality of blow-off holes provided in the blow-off pipe 3 into the settling tank 1, and the initial flocs in the feed are captured by the agglomerated floc layer B formed by the uniform upward flow. It becomes a finer coarse flock. The clarified liquid flows upward to form a clarified layer A. A part of the coagulated floc layer B settles to the lower part of the settling tank 1 and becomes concentrated sludge, and the sludge scraper 5 is rotated to further concentrate the sludge to form a concentrated sludge layer C. This thickened sludge is returned into the feed supply pipe 2 by the return pump 8. The interface between the clarified layer A and the coagulated floc layer B in the settling tank 1 is detected by an interface detector 11 so that it does not exceed a set height, and the interface is controlled by drawing out the thickened sludge with a drawing pump. The clear water overflows from the overflow part 13 at the upper part of the tank 1 and is discharged.

According to the present invention, the feed in the supply pipe, which is rapidly stirred, and each layer in the sedimentation tank, which is slowly stirred, are mixed and stirred by completely different driving sources, so that the feed and each layer are mixed and agitated by completely different driving sources. , the reaction of the feed can be sufficiently stirred without interference,
A good initial floc is formed. In addition, since the feed supply pipe equipped with a blow-off pipe with multiple blow-off holes is rotated to stir the inside of the tank, the initial flocs are evenly dispersed, and even if a large amount of initial flocs flows out into the tank, there is no flow inside the tank. In addition to suppressing turbulence in the flow, it also improves the uniformity of the upward flow within the tank, and has the advantage of producing dense, coarse, and highly uniform flocs. Moreover, it is 10 to 20 times more than conventional (10 to 20
m/h) can be expected, the device can be made smaller, the installation area can be reduced, and it also has the function of a sludge thickening tank.

[Brief explanation of drawings]

The drawing is a schematic sectional view showing a specific embodiment of the device of the present invention. 1...Sedimentation tank, 2...Feed supply pipe, 3...
Blower pipe, 4... stirring blade, 5... sludge scraper, 6...
...Inflow pump, 7...Drug supply pump, 8...Return pump, 9...Blowout hole, 10...Stirring drive unit,
11... Interface detector, 12... Extraction pump, 1
3... Overflow part, 14... Drive part, A... Clear layer,
B...Agglomerated floc layer, C...Thickened sludge layer.

Claims (1)

[Scope of Claims] 1. A rotatable feed supply pipe is installed vertically in the sedimentation tank, and a blowout pipe having a plurality of blowout holes is provided at the tip of the feed supply pipe, and further, the feed A mechanism for supplying raw wastewater and sludge to the upper part of the feed pipe, a mechanism for supplying additives from at least two locations, the upper and lower parts of the feed pipe, a mechanism for mixing and stirring the feed in the feed pipe, and a feed pipe. A coagulation and sedimentation treatment device comprising a sludge scraping mechanism provided at the bottom of a sedimentation tank that rotates integrally with the sludge extraction means interlocked with an interface detector. 2. The coagulation and sedimentation treatment apparatus according to claim 1, wherein a layer of concentrated sludge is formed in the sedimentation tank below the blow-off pipe.