JPH06292807A - Filter machine built-in type thickener - Google Patents

Abstract

PURPOSE:To reduce a water area and to provide the small-sized thickener by adding a fluidized filter layer which can remove small flocks and can be regenerated by washing to the thickener. CONSTITUTION:This thickener includes a flocculation reaction vessel 10 which flocculates suspended materials by mixing a flocculating agent into waste water contg. the suspended materials and stirring the waste water and a settling and separating vessel 20 which settles the formed flocs and separates the flocs from the waste water. Filter media 30 which float by covering the waste water surface in the vessel and a filter medium washing and circulating device 31 which takes the filter media out of the water surface, washes the media and returns the media onto the water surface are disposed within this settling and separating vessel 20. The small flocs ascending without being completely settled in the settling and separating vessel 20 of the thickener are removed by the filter media 30 and, therefore, the water area part for setting the small flocks which is heretofore required for the conventional thickeners is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickener with a built-in filter, which can obtain excellent separation performance in a small installation area.

[0002]

2. Description of the Related Art Various types of colloidal substances such as clay are contained as suspended solids (SS) in construction wastewater that flows out during construction work such as civil engineering and construction, and if discharged as it is, it causes environmental pollution. Therefore, it must be purified within a certain standard value. Conventionally, when purifying such construction wastewater, a flocculant is added to the wastewater, and the suspended substances dispersed in the wastewater are aggregated to form flocs, and the sedimentation speed is increased and sedimentation is separated with a thickener. Is being done.

Conventionally used thickeners include a square thickener shown in FIG. 4 and a circular thickener shown in FIG. In both thickeners, a flocculation reaction tank 10 that flocs floating substances by mixing agitation agent with turbid wastewater H containing suspended substances and stirring, and a settling partition that separates flocs from wastewater And a separation tank 20. The waste water containing the flocs formed in the flocculation reaction tank 10 is sent to the sedimentation separation tank 20. Now, the treated water volume of thickener is M (m ³ / H), and the sedimentation velocity of floc is V (m / H).
Then, the water area S of thickener is represented by S = M / V. The water area S of the conventional thickener is set to be 3 to 6 m / H or less when the sedimentation velocity V in the final partition portion is square, and 2 to 3 m / H or less when it is circular. Most sediment suspended in the wastewater has a sedimentation velocity of 10 m / H.
As described above, the flocs become very large, and most of them settle in the initial section A where the flow velocity is relatively fast in the settling separation tank 20. The subsequent section B is a section required for sedimentation separation of flocs having a smaller sedimentation velocity V.

[0004]

In the conventional thickener, most of the flocs formed in the flocculation reaction tank 10 are settled and separated in the first section A, but the flocs having a small settling speed are not formed. It cannot be removed completely and the standard value of treated water cannot be satisfied. Therefore, it is necessary to add the section B to increase the water area, which inevitably increases the installation area of the thickener.

As the thickener becomes large, the processing amount becomes 50t.
In wastewater treatment facilities of / h or more, the individual components of the plant are brought to the construction site for assembly, which increases costs. In particular, in the case of a circular thickener, a bent iron plate is transported to the site for welding and assembled, and once assembled, it cannot be diverted, so it was discarded at one site, which was very uneconomical. Therefore, there has been a strong demand for a miniaturized thickener that can be integrated as a unit.

The present invention has been made by paying attention to the above-mentioned conventional problems, and by adding a washable and reproducible fluidized filter layer capable of removing small flocs to the conventional thickener, the water area is reduced and the size is reduced. Intended to provide Thickener.

[0007]

Means for Solving the Problems The present invention which achieves the above-mentioned object, comprises a flocculation reaction tank for flocculating a suspended substance by mixing a flocculant with waste water containing the suspended substance and stirring the mixture, The present invention relates to a thickener equipped with a settling separation tank for settling flocs to separate them from wastewater. In the settling separation tank, a filtering material that covers the drainage surface in the tank and floats, and the filtering material is taken out from the water surface and washed. And a filter material washing / circulating device for returning to the surface of the water.

[0008]

[Function] Small flocs that cannot be completely settled in the Thickener settling tank and rise up are removed by the filter material floating on the water surface. The filter material with the flocs attached is pumped up with a filter material cleaning circulation device, washed, regenerated and returned to the water surface for reuse. By forcibly removing small flocs, the water area required by the conventional thickener can be greatly reduced.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a square thickener according to an embodiment of the present invention. The drainage H is stored in the drainage tank 1. The drainage H pumped up from the drainage tank 1 by the pump P is sent to the upper part of the flocculation reaction tank 10 through the line mixer 3 installed in the pipe 2. The agglutination reaction tank 10 is a closed type container having a stirrer 13 inside which is partitioned into a plurality of shelves 11 (three partitions in the figure) and a stirring blade 12 is installed in each partition. The inorganic coagulant storage tank 14 stores an inorganic coagulant such as base aluminum chloride (PAC), which is supplied to the inlet side of the line mixer 3 through the pipe 15 by the pump P _1. ing.
Further, an organic flocculant such as polyacrylamide is stored in the polymer flocculant dissolution storage tank 16 while being stirred by a stirrer 17, and is supplied into the intermediate section of the flocculation reaction tank 10 via a pipe 18 by a pump P _2. It is supposed to be done.

The sedimentation tank 20 has a prismatic shape, and is provided with a cylindrical section 21 having a conical bottom and an open top.
The tank is composed of a tank and a tank B which is partitioned by a partition wall 22 and communicates with each other through an opening 23, and screw conveyors 25 and 26 which are commonly rotated by a motor 24 are provided at the bottom of each tank. . The slurry S scraped by the screw conveyors 25 and 26 is taken out of the sedimentation separation tank 20 by a slurry drawing pump P _S and sent to a slurry tank (not shown) through a pipe 27.

Further, in the upper part of the B tank of the sedimentation separation tank 20,
A filter medium 30 that covers the drainage surface of the tank and floats up, and a filter medium cleaning circulation device 31 that takes the filter medium 30 out of the water surface and cleans it back to the water surface are provided. Filter material 30
Is a granular material having a specific gravity smaller than that of water and having a large surface area that easily floats. In this embodiment, for example, plastic is used.

In this embodiment, the filter material washing / circulating device 31 is a vertical screw conveyor 33 driven by a motor 32, a gutter 34 mounted on the upper part thereof, and a washing water device 35 supplied to the upper part of the gutter 34. It has and. A net (not shown) is laid on the bottom surface of the gutter 34, and the filter medium 30 is returned to the water surface by removing the flocs while flowing down the gutter 34 together with the washing water. It flows down the bottom, is taken out from a branch pipe (not shown), and is returned to the drainage tank 1, for example. As the cleaning water, the treated water W after passing through the filter medium 30 may be used and may be pumped up by a pump (not shown) and supplied.

At the upper part of tank B, weir 4 from which treated water W flows out
0 is provided. It should be noted that it is possible to add a B ₁ tank to the B tank to cope with fluctuations in the amount of raw wastewater. Next, the operation will be described. The drainage H of the drainage tank 1 is pumped,
The inorganic coagulant from the inorganic coagulant storage tank 14 is rapidly stirred by a line mixer and sent to the coagulation reaction tank 10.
The inorganic coagulant promotes the action of the organic coagulant in the subsequent step, and when it is uniformly mixed in the wastewater in a short time by the rapid stirring of the line mixer, its coagulation promoting effect is exhibited. In the coagulation reaction tank 10, the organic coagulant sent from the polymer coagulant dissolution storage tank 16 is further mixed, and is allowed to flow down in the tank while being gently stirred by the stirrer 13. During that time, the reaction between the suspended solids in the waste water and the flocculant is promoted, and the fine suspended solids grow into coarse flocs. In this case, the flocculation reaction tank 10 is a closed container, and since waste water is put in from above and taken out from below, short circuit of waste water and accumulation of flocs in the tank are prevented, and a sufficient flocculation reaction is performed.

Wastewater containing flocculated suspended solids is blown up to the bottom of the cylindrical section 21 in the tank A of the settling separation tank 20 and rises to flow down from the upper opening into the tank A. It flows into the B tank through the opening 23. Meanwhile, many coarse flocs separate from the wastewater and settle to the bottom of tanks A and B. However, the small flocs that cannot fully settle along with the drainage and rise in the B tank. The ascending flocs are captured by the filter medium 30 floating in a thick layer on the water surface and separated and removed from the wastewater. In this way, only the treated water W whose amount of suspended solids SS has been cleaned within the standard value is taken out of the tank from the overflow weir 40 and discharged.

The filter medium 30 which has captured the flocs is continuously pumped out from the water surface by the vertical screw conveyor 33 of the filter medium cleaning / circulating device 31, discharged to the upper part of the gutter 34, and supplied from the cleaning water device 35. Gutter 34 with wash water
Run down. The flocs adhering during that time are removed, discharged from the lower end of the gutter 34, and returned to the water surface again. Since the filter material 30 is continuously washed and regenerated, the filter material 30 is not clogged.

Thus, the small flocs that cannot be completely settled and separated in the A and B tanks are captured and removed by the filter medium 30,
The water area of the portion shown in FIG. 4B, which is required to settle and separate the small flocs in the related art, is unnecessary, and the size of the settling / separation tank 20 corresponding to that is reduced and the size is reduced. FIG. 2 shows another embodiment, which is applied to a circular thickener.

In this embodiment, the tank A and the tank B of the sedimentation separation tank 20 are connected in a conical bottom cylindrical shape of the same size,
A filter medium 30 and a filter medium cleaning / circulating device 31 are arranged in the B tank. The slurry S that has settled at the bottom of each tank is
It is taken out by the slurry extraction pump P _S installed in each. Other functions and effects are similar to those of the first embodiment.

FIG. 3 shows still another embodiment, which is a sedimentation separation tank 20.
It is a circular thickener with one tank. The floc-containing wastewater from the flocculation reaction tank 10 is tangentially fed to the middle portion of the cylindrical section 21A having the upper and lower openings installed in the sedimentation separation tank 20, and becomes a centrifugal flow to be vertically divided and divided in the A tank. Flow and flocs collide with each other to promote coarsening. Then, the large flocs settle to the bottom of the tank, and the small flocs are carried along with the rising wastewater toward the water surface, and are captured and removed by the filter medium 30. This embodiment is more compact than the first and second embodiments, and is suitable when the amount of treated water is relatively small or when flocs are likely to become coarse.

[0019]

As described above, according to the present invention, the flocculation reaction tank for flocculating the suspended matter by mixing and stirring the flocculant in the wastewater containing the suspended matter, and the floc thus formed. In a thickener settling separation tank equipped with a settling separation tank that settles and separates the wastewater from the wastewater, a filter material that covers the drainage surface in the tank and floats is taken out from the water surface, washed and returned to the water surface. Since a material washing and circulation device is installed, small flocs that cannot be settled in the thickener settling separation tank and rise without being removed can be removed by the filter material floating on the water surface, and the small flocks required by conventional thickeners can be removed. It is possible to greatly reduce the water area portion for sedimentation and separation, and as a result, it is possible to obtain an effect that the entire size can be made extremely small.

As a result, the site where the thickener is installed on the construction site can be small, and the on-site installation and dismantling work of the wastewater treatment equipment can be facilitated. The wastewater treatment equipment is divided into multiple units to be manufactured for large-scale treatment on site. It is extremely useful in practice because it can be integrated into a capacity plant.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention.

FIG. 2 is a schematic view of another embodiment of the present invention.

FIG. 3 is a schematic view of still another embodiment of the present invention.

FIG. 4 is a schematic view of a conventional square thickener.

FIG. 5 is a schematic view of a conventional circular thickener.

[Explanation of symbols]

 1 Drainage Tank 10 Coagulation Reaction Tank 14 Inorganic Coagulant Storage Tank 16 Organic Coagulant Storage Tank 20 Sedimentation Separation Tank 30 Filtration Material 31 Filtration Material Cleaning Circulator

Claims (1)

[Claims] 1. A flocculation reaction tank for flocculating suspended matter by mixing and stirring a flocculant in wastewater containing suspended matter, and a settling separation vessel for settling the flocs formed and separating them from wastewater. In the thickener provided, the settling / separation tank is provided with a filter material that covers the drainage surface in the tank and floats up, and a filter material cleaning circulation device that takes the filter material out from the water surface and cleans it back to the water surface. Thickener with a built-in filter.