JPH04108502A - Flocculation and device therefor - Google Patents

Abstract

PURPOSE:To realize high performance and low cost for flocculation by providing injection pipes in a plurality of mixing pipes, each one end thereof being opened to the dispersion chamber of a liquid supplying chamber, the other end thereof to the solid-liquid separation chamber of the same, and setting the flow rate of the liquid mixture in the mixing pipe within the range defined by the inequality 10<Re<10<5>, and that of the injection liquid in the injection pipe within the range of 10<Re<10<4>. CONSTITUTION:A liquid supplying chamber 1 supplying a liquid 2 to be treated is provided with a dispersion chamber 3, and a partition wall 8 is provided between a dispersion chamber 3 and a solid-liquid separation chamber 4. One end of each of the plurality of mixing pipes 5 is opened to the dispersion chamber 3 and the other to the solid-liquid separation chamber 4. An injection pipe 6 is provided in each of mixing pipes 5, meeting the central axis in alignment. A flow of an injected liquid 10, which is supplied in a state of a laminar flow from a discharging port 14 of the injection pipe through a porous material and a laminar flow of the liquid 2 to be treated, which flows into the monotube part of a mixing pipe on the downstream of the discharging port 14 of the injection pipe flow in contact with each other, and on the boundary surface between these phase flows, the fine particles of the liquid 2 to be treated violently collide with each other over and again, whereby huge flocks are formed during the passage of these particles through the mixing pipes. Number of the mixing pipes is determined such that the flow rate of the liquid mixture 7 during the passage of the total quantity of the liquid mixture 7 through each mixing pipe 5 is maintained within the range of 10<Re<10<5>, and the flow rate of the injected liquid 10 in the injection pipe 6 within the range of 10<Re<10<4>.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to dilute polluted water such as tap water/industrial water collection water (river water, underground river water, groundwater, lake water), biological/physicochemical treated water, etc. Concentrated raw sludge such as wastewater from wastewater and filter ponds at water treatment plants, sludge from high-speed flocculation sedimentation tanks, and sludge from chemical sedimentation tanks is converted into a supernatant liquid (
This invention relates to a flocculation method and a flocculation device for separating water into water (tap water, commercial water, reprint water, gray water).

``Prior art'' As a device for separating dilute contaminants (fine particles) from the liquid to be treated, it is possible to remove the filamentous bacteria by submersion filtration, or by adding a flocculant. A sedimentation tank and/or a filtration tank are used to separate flocculated fine particles. In the sedimentation tank, flocculated fine particles (flocs) generated by adding a flocculant to the liquid to be treated are supplied to a liquid supply cylinder. The flocs are allowed to settle under the action of gravity while reaching the overflow weir of the solid-liquid separation chamber.By adding a coagulant, the charge on the sludge surface of the fine particles is reduced, and the repulsive energy is reduced, causing the flocs to settle between the fine particles. Collision occurs and flocs are formed. A method is adopted in which the treated liquid that has formed flocs is passed through a bed filled with fine particles (filter tank).

[Invention or problem to be solved] This invention improves the solid-liquid separation performance by more than several times the current level in order to improve the quality of tap water, industrial water, reprint water, and gray water. Fine particles or dispersed floating fine particles are coagulated and separated by using an electrolyte in the liquid to be treated as a flocculant, or by adding an electrolyte to the liquid to be treated to instantly form giant flocs.

Since the flocs are large and a large solid load can be taken, the sedimentation tank and filtration tank can be made smaller and lighter. Sedimentable fine particles are l
When it is less than 0 mg/l, the distance between particles is large, and even if there is a surface potential difference that can cause collision between particles, there is little chance of collision between particles, and even if flocs are formed, the flocs are small and there is no agglomeration removal effect. Often low.

The purpose is to provide an inexpensive device with good performance for coagulating and removing fine particles of around 1 micron.

[Means for Solving the Problems] The present inventor first agglomerates fine particles from a liquid to be treated containing fine particles to form a huge floc, and settles the solids to a solid-liquid separation tank with a solid load of 50 to 250 kg. /m' days, he invented an apparatus and aggregation method for efficiently separating the supernatant from
(See Publication No. 10).

The flocculating apparatus of the present invention is similar to the flocculating apparatus described in Japanese Patent Application No. 63-155624, and includes a liquid supply chamber for supplying the liquid to be treated, a dispersion chamber for dispersing the liquid to be treated, and a mixing chamber opened in the dispersion chamber. A pipe is provided, an injection pipe is inserted into the mixing pipe, and the flow of injected liquid into the mixing pipe from the injection pipe outlet comes into contact with the flow of the liquid to be treated flowing into the mixing pipe, and the interface between Creates an electrolyte concentration difference between fine particles,
Based on this, the reduction in repulsion potential energy is 1 to 5X
Violent collisions are repeated even between fine particles of 103 sm, which are difficult to collide with, until they reach the mixing tube outlet (within 2 to 3 seconds).
．． Forms 5-11 giant flocs. This mixture is
The floating fine particle flocs 22) in the mixed liquid sent to the solid-liquid separation chamber float and are removed from the solid-liquid separation chamber by the scraper arm 20), and the huge flocs of sedimentary fine particles are removed from the solid-liquid separation chamber. The sludge is discharged from the sludge discharge port 19) provided at the bottom, and is recycled and reused as necessary. Supernatant liquid 21)
is taken out of the system from a supernatant liquid outlet provided below the liquid level in the solid-liquid separation chamber.

In the flocculation method of the present invention, when the fine particle concentration in the liquid to be treated is low (10 ppm or less), when the fine particle concentration is low (10 ppm or less), the flocculation aid is By adding a large number of fine flocculation aids between the fine particles to be removed, the collision effect between the target fine particles (including the flocculation aids) is increased and the ability to form flocs is increased. It's a method. The sludge (including the flocculation aid) that has been flocculated and concentrated with the addition of a flocculation aid is recycled and reused, and the addition of a flocculation aid is not required in the washed waste water and waste sludge from the rapid filtration ponds, which have a high concentration of fine particles.

The flow rate of the mixed liquid (processed liquid and injection liquid) in the mixing tube is set to 10<
When Re<105, the flow rate of the injection liquid in the injection tube was set to 5<R
By maintaining e<105, both liquids are brought into contact within the mixing tube, and the coagulation and separation action is almost completed.

The liquid to be treated by the flocculation device of the present invention includes river water containing dilute fine particles, ground water, lake water, industrial/agricultural water,
Underflow water, biological/physicochemical treated water, and water treatment plant wastewater (filtered oil washing wastewater discharged from water treatment plants, settling tank sludge) are referred to as treated liquids.

The injection liquid may be biological treatment supernatant water, physicochemical treatment supernatant water, low concentration contaminated industrial wastewater, seawater, tap water, distilled water, irrigation water and/or industrial water (lake water, river water, groundwater, etc.). If the electrolyte concentration of the treated solution is low and there is no difference from the electrolyte concentration of the injection solution, add an electrolyte to the treatment solution or use an aqueous solution containing an electrolyte as the injection solution, such as an aqueous alkaline earth metal salt solution, an alkali metal Salt aqueous solution, polymer flocculant, PC! +++, AI+÷10 aqueous solution can also be used.

Coagulation aids to be added when the concentration of fine particles in the liquid to be treated is low include diatomaceous earth, bone char powder, carbon powder (coal, coconut husk, activated carbon), magnesium carbonate powder, calcium phosphate powder, mica, feldspar, white clay, Pottery stone, talc, bentonite, kaolin, clay, kaolin, dolomite, magnesia, magnesium silicate, chromium, chromium magnesia, magnesia chromium alumina, silica,
These include fine powders of ceramic raw materials such as waxite, titanium oxide, calcareous aluminate, dicalcic silicate, spinel, and norconite, finely pulverized fibers, and fine powder of water-insoluble organic substances.

Porous material of injection pipe, hole diameter 05-8I in annular part of mixing pipe
By installing the I+n porous materials (perforated plates) in multiple stages, the liquid that has passed through the holes in the porous materials (perforated plates) will each have a uniform velocity at the discharge port downstream of the porous materials. Even if the lengths of the mixing tube and the injection tube are shortened, the flocculation and separation performance does not deteriorate, so it is possible to downsize the flocculation device.

The present invention will be explained below based on the accompanying drawings.

FIG. 1 shows an example of the aggregation apparatus of the present invention, which is a vertical type apparatus. In the flocculation apparatus, a chamber to which the liquid to be treated 2) is supplied is called a liquid supply chamber 1), and a dispersion chamber 3) is provided in the liquid supply chamber. One or more mixing tubes 5) (2 in Fig. 1) in the dispersion chamber.
One end of the mixing tube 5) with both ends open in the dispersion chamber is provided as a supply port for the liquid to be treated, and the other end is a mixing tube discharge port that directly discharges the aggregates into the solid-liquid separation chamber 4). 15) and
The injection pipe 6) is connected to a plurality of mixing pipes, and the injection liquid supply pipe central axis 11
) Injection tube center axis 12) Mixing tube center axis 13) It is a diagram of a device in which one tube is provided with their respective center axes being unified (unification is not necessarily required if a porous material is provided). The injection pipe discharge port 14) opens toward the downstream side of the mixing pipe. A partition wall 8) is provided between the dispersion chamber and the solid-liquid separation chamber, and the flow of the injection liquid 10) that passes through the porous material 1B) and is supplied in a laminar flow from the injection tube outlet 14) and the mixing tube. The laminar flow of the liquid to be treated flows from [7) into the single pipe part 1g) of the mixing tube downstream of the injection tube outlet, and at the interface, the Violent collisions between the fine particles of the liquid occur repeatedly, forming huge flocs while passing through the mixing tube. The settled flocs are discharged from the sludge discharge port 19). The liquid supply ports of the plurality of mixing tubes are maintained at the same water level to equalize the amount of water flowing into each mixing tube. The number of mixing tubes is determined so that the total amount of the mixed liquid 7) of the amount of liquid to be treated and the amount of injection liquid is maintained at a flow rate of 10<Re<105 through each mixing tube. The flow rate of the injection liquid in the injection tube is also 5<Re<
105.

The reason why the solid-liquid separation performance of the present invention is high is that when the fine particles of the liquid to be treated come into contact with the injection liquid and are washed, and the electrolyte concentration difference between the two liquids is large, the repulsion potential decreases between the fine particles based on this. This is because it causes a severe agglomeration effect, and the mixing and agglomeration effect is repeated to form huge flocs toward the downstream side of the mixing pipe. Generally, when the difference in electrolyte (ion) concentration between the two solutions is large, the bonding force between aggregated fine particles and floc particles seems to be strong. Desirably, if the electrolyte concentration difference between the injection solution and the treated solution is 0.1 mg/1 or more, flocs will be easily formed, and if it is 10 mg/1 or more, the floc-forming ability will be strong. 2X to 5 mg/1 or more will form flocs, but the drug cost will be high and it is not economical.

If the flow rate in the mixing tube is Re>105, no flocs will form. If Re < 105, flocs will form. If 10>Re, the throughput per mixing tube will be small and the processing cost will be high. Even if the formed flocs are once destroyed when the flow velocity in the mixing tube becomes 105<Re<105, the flocs will still be formed if Re<105 is maintained. If the injection velocity of the injection liquid into or from the injection tube is Re>105, no flocs will be formed. If Re<105 is maintained, floc growth is promoted. If Re < 5, the amount of injection tubes to be processed for one injection tube will be small, and the processing cost will be high.

The amount of the injected liquid is approximately 200 z or less, preferably 30 to 1% of the liquid to be treated. If it is less than 1%, the flocculation effect is low, 20
oz or more, the floc-forming ability remains the same. 2002
If it exceeds , the load on the solid-liquid separation chamber will be too large, and the effect of increasing the amount of injected liquid will not be recognized.

In the case of a liquid to be treated with a low concentration of pollutants, the distance between fine particles is often 100 August long or more.If the distance between particles is larger than 100 August long, there are fewer collisions between particles, resulting in small flocs and agglomeration. Performance will be significantly degraded. Therefore, a flocculation aid with a diameter around the same as that of the particles in the liquid to be treated and a large specific gravity, and flocculated and separated sludge (including the flocculation aid) are added as a flocculant and are recycled and reused. The amount of addition is lO~lx ]O'mg/l is added to the liquid to be treated to enhance the collision effect and form giant flocs for coagulation and separation. The aggregation effect is not significant below tomg/l. At 5mg/1 or more of 1xlO, there is no noticeable effect just by adding it.

The hole diameter of the porous material (16) attached to the annular portion of the injection pipe and mixing pipe is changed depending on the diameter of the fine particles in the injection liquid and the liquid to be treated. 1mm in the liquid to be treated
The above solid particles are removed by an inexpensive filter, and the fine particle diameter here refers to a diameter of 1 mm to 0.1 micron. In order to reduce the size of the flocculation apparatus by installing a porous material, it is necessary that the injection liquid and the liquid to be treated that pass through each type of porous material have as uniform a velocity as possible. Porous material is antibacterial 001
Powder with a diameter of ~5 mm, porous plates made of metal, inorganic, or polymeric resin with a hole diameter of 0.001 to 8+ nm, woven fabrics, knitted fabrics, nonwoven fabrics, nets, sponges (continuous fine cell diameter), each of these materials individually Alternatively, a combination of layers may be mentioned. The loading height of the porous material is 0.1 to 500 mm, and the pressure loss at an average velocity in the tap water pipe of 1 mm/sec is 0.01.
~10. O[It is desirable to keep it within 10 mm. If the pressure loss is less than 0.01mm, the rectification effect will be small and the pressure loss will be less than 0.01mm.
More than m+n requires a large amount of power and is uneconomical.

Example-1 Paper manufacturing wastewater with BOD of 250 ppm and COD of 230 ppm was biologically treated for 1500 m for 37 days, resulting in a BOD of 5 p.
pm, COD] 3 ppm, SS 6 ppm, electrolyte concentration 4
It is 20 ppm. This treated liquid is subjected to sand filtration (average filtration rate of 4 m/hr) and used as reused water. On the other hand, 50 ppm of diatomaceous earth (average particle diameter 35 microns) was added to the above biological treatment liquid, and the injection liquid was poured into the supply port of the treated liquid of the flocculation apparatus shown in Fig. 1 of the present invention for 1500 m'7 days.
The supernatant liquid is removed from 30 cm below the water surface of the solid-liquid separation chamber, and the settled fine particles are removed from the bottom of the solid-liquid separation chamber, and the removed sludge (sludge concentration 3.7%) is transferred to the biological treatment liquid. was added as diatomaceous earth and recycled for reuse.

The agglomeration device is a mixing tube (diameter 12011I1m, length 180
0IIl111) and injection tube (diameter 25m+a, length 13
64 (4 rows x 16
Two sets of wood/sets were placed in two dispersion chambers, and the water level of the dispersion chambers was set 45 mm above the water level of the solid-liquid separation chamber.

Table 1 shows the treatment results of the sand filter treated water and the treated water of the flocculation device of the present invention.

Table-1 Sand filtration coagulation device coagulation aid None Diatomite diatomaceous earth recirculation sludge coagulation aid addition amount mg/ ] Treated water quality BOD 〃2 3'l IC0D
〃 5 5 2 2SS
3 4 1 1 Example-2 River water, KMnOa consumption 3.5 ppmS turbidity 73.6
A mixed solution of 874 general bacteria (number/rQ1), chromaticity 1.4, and 30 ppm of bentonite was added to the flocculation apparatus of the present invention [12 tubes (4 rows, combining the same mixing tube and injection tube as in Example 1). x 3 bottles) was supplied to a dispersion chamber equipped with 3 bottles. Set the water level in the dispersion chamber to 50 m above the water level in the solid-liquid separation chamber.
It was installed on +s. The fine sedimentary particles were discharged from the bottom of the solid-liquid separator, and the discharged sludge was added to the liquid to be treated (river water) as bentonite and recycled for reuse. The supernatant liquid is the quality of the treated water (A) discharged from 25ca+ below the water surface of the solid-liquid separation chamber, while the Iku River water is the quality of the treated water (B) that is filtered through the sand layer at a slow speed of 4 to 5 m/day. Table 3 shows the sludge concentration when river water is collected in a cylinder and the sludge is sedimented and concentrated, and the sludge concentration in (8) is shown in Table 2. The filter media for slow sand filtration is shown in Table 2.

Table-2 From the top Sand diameter mm Thickness mm Fine sand
0.2~0.4 800 coarse sand
3.2 150 fine gravel 5
~9140''] l~18 140 stones 22~31 250 Table-3 Turbidity chromaticity HnO, consumption jl ppm General bacteria/ml Sludge concentration ppm Sedimentation time 1 min 4 hr River water A B 1.4 0 0 3 .5 [331,13 Example-3 The same flocculation device as in Example-1 of the present invention is used for sedimentation concentration for cleaning wastewater from rapid filtration oil in a river water purification plant.Filtration oil cleaning Table 4 shows a comparison of the concentrated sludge concentration when 5 ppm of Ca++ was added to the wastewater and the solid matter load was 250 kg/m'day and the change over time of the sludge collected in the measuring cylinder.

Table-4 Sedimentation time Sludge concentration (%) Time Graduated cylinder Coagulation device of the present invention 0 0.67
0.671/60
3261 2.87 5.584
4.06 24 5.61 [Effects of the Invention] Since the aggregation method of the present invention can utilize the electrolyte in the liquid to be treated as a flocculating liquid for fine particles in the liquid to be treated, chemical costs can be reduced.

In the flocculation method of the present invention, alkali metal salts and alkaline earth metal salts can be added to the liquid to be treated as flocculants, and since their concentration is low, there is no concern about water purification or environmental pollution.

Even if the concentration of fine particles in the liquid to be treated is low, the flocculating effect can be increased by adding inorganic fine EB particles free of eluates as a flocculation aid. Furthermore, even if the sedimented and concentrated sludge (including flocculation aid) is recycled and reused as a flocculation aid, it produces the same flocculation effect as using the flocculation aid alone, and the SS in the treated water maintains the same water quality as slow filtration. It is economical.

Since the solid load and the amount of water to be treated are large, the sedimentation tank and filter connection can be downsized, and the same water quality as that of a slow-speed filter connection can be obtained.

Since the flocculation device of the present invention forms giant flocs in the mixing tube simply by contacting the injected liquid and the liquid to be treated, there is no need for power for collision or for a floc growth chamber.

Since the interface between the flocculated sludge and the supernatant liquid in the solid-liquid separation chamber is clearly defined, the sludge can be automatically pulled out at a rate commensurate with the sedimentation rate, making operation management easy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the aggregation device of the present invention. FIG. 2 is a sectional view in which the discharge port of the injection tube is opened in multiple stages and the injection tube and the mixing tube are loaded with porous material. J, Liquid supply chamber 2 Liquid to be treated 3: Dispersion chamber 4: Solid-liquid separation chamber 5 Mixing pipe 6/Injection pipe 7 Mixed liquid 8/Partition wall 9
・Injection liquid supply pipe 1〇-Injection liquid 11 Injection liquid supply pipe center axis 12 Injection pipe center axis 13: Mixing pipe center axis 14
: Injection tube outlet 15. Mixing pipe discharge port 16 Porous material 17 Annular part 18 Single pipe part 19: Sludge discharge port 20: Scraping arm 21: Supernatant liquid 22/Floatable fine particle floc Patent applicant Kazuji Fukunaga No. ■ Ward: Figure

Claims (1)

[Scope of Claims] 1) A dispersion chamber 3) consisting of a liquid supply chamber 1) and a solid-liquid separation chamber 4), in which the liquid to be treated 2) is dispersed, one end of which is the dispersion chamber, and the other end of which is the dispersion chamber. The flocculation device has a structure in which one or more mixing tubes 5) are provided whose ends open into the solid-liquid separation chamber, and one or more injection tubes 6) are further provided for injecting the injection liquid 10) into the mixing tubes. When separating the polluted fine particles and the supernatant liquid from the liquid to be treated 2), the flow of the mixed liquid 7) of the injection liquid and the liquid to be treated in the mixing tube is 10<Re<10^5, and the flow of the injection liquid is A flocculation method for separating fine particles causing contamination from a liquid to be treated and a supernatant liquid, characterized in that the flow in the injection tube is maintained in the range of 5<Re<10^4. 2) The aggregation method according to claim 1, wherein the amount of the injected liquid is 1 to 200% of the amount of the liquid to be treated. 3) The flocculation method according to claim 1, wherein the difference between the electrolyte concentration in the injection solution and the electrolyte concentration in the treated solution is in the range of 0.1 mg/l to 2 x 10^5 mg/l. 4) The aggregation method according to claim 1, wherein the electrolyte concentration in the injection liquid is lower than the electrolyte concentration in the liquid to be treated. 5) The aggregation method according to claim 1, wherein the electrolyte concentration in the injection liquid is higher than the electrolyte concentration in the liquid to be treated. 6) The aggregation method according to claim 1, characterized in that an electrolyte is added to the liquid to be treated. 7) Add 30 to 1 x 10^5 mg/l of coagulation aid to the liquid to be treated.
2. The aggregation method according to claim 1, wherein: 8) The flocculation method according to claim 1, wherein the flocculated and separated sludge (containing a flocculation aid) is added to the liquid to be treated and used for circulation. 9) The flocculation device according to claim 1, wherein a porous material 16) is attached to the annular portion 17) of the mixing tube.