JP2558547B2 - Coagulation method and coagulation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to dilute pollutants such as tap water / industrial water sampling water (river water, river downflow water, groundwater, lake water), biological / physicochemically treated water, etc. And coagulation method to separate concentrated pollutants such as washing drainage of filtration basin of water purification plant, high-speed coagulation sedimentation effluent sludge, chemical sedimentation effluent sludge into supernatant liquid (clean water / water / reused water / drainage) And a flocculating device.

[Prior Art] As a device for separating dilute pollutants (fine particles) in the liquid to be treated from the liquid to be treated, a device for removing the contaminants by a flooded filter bed on which filamentous bacteria have adhered or by adding a coagulant is used. A precipitation tank and / or a filtration tank for separating agglomerated fine particles are used. In the settling tank, agglomerated fine particles (flocks) generated by adding a coagulant to the liquid to be treated are supplied to the liquid supply cylinder, and the flocs are generated under the action of gravity while reaching the overflow weir of the solid-liquid separation chamber. It is to settle. Addition of a coagulant lowers the electric charge on the sludge surface of the fine particles, reduces the repulsive energy, and causes collisions between the fine particles to form flocs. A method is used in which the liquid to be treated on which flocs are formed is subjected to a water treatment of a fine particle packed bed (filter tank).

[Problems to be Solved by the Invention] In order to improve the quality of tap water, irrigation water, reused water, and tap water, the present invention improves solid-liquid separation performance to several times or more of the current level, and microorganisms of about 1 micron , Fine particles, dispersed floating fine particles are used as an aggregating agent for the electrolyte in the liquid to be treated, or an electrolyte is added to the liquid to be treated to form huge flocs in an instant and the aggregate is separated. .

Since the flocs are large and the solid load can be large, the sedimentation tank and the filtration tank can be made compact and lightweight. 10 fine sedimentable particles
When the concentration is less than mg / l, the distance between particles is large, and even if there is a difference in surface potential that can cause collision between particles, there is little chance of collision between particles. Often low.

It is an object of the present invention to provide at low cost a device having a good performance of coagulating and removing fine particles of around 1 micron.

[Means for Solving the Problem] The present inventor firstly aggregates fine particles from a liquid to be treated containing fine particles to form huge flocs, and causes the flocs to settle, and the solid-liquid separation tank is loaded with solid matter of 50 to 250 kg. / m ^{2 It took more than a} day to invent a device and an agglomeration method for efficiently separating it from the supernatant, and filed as Japanese Patent Application No. 63-155624 (see Japanese Patent Application Laid-Open No. 2-52010).

The aggregating apparatus of the present invention, like the aggregating apparatus described in Japanese Patent Application No. 63-155624, in the liquid supply chamber for supplying the liquid to be treated,
A dispersion chamber for dispersing the liquid to be treated and a mixing pipe open to the dispersion chamber are provided, an injection pipe is inserted into the mixing pipe, and a flow for injecting the injection liquid into the mixing pipe from the injection pipe discharge port and flowing into the mixing pipe. Comes into contact with the flow of the liquid to be treated, which causes an electrolyte concentration difference between the fine particles and the fine particles at the interface, and the reduction in the energy of the counter power generation is 1-5 × 10 ⁻³ mm.
The violent collision is repeated even between the fine particles which are difficult to collide, and a huge floc of 0.5 to 1 mm is formed up to the mixing pipe discharge port (for 2 to 3 seconds). This mixed liquid is sent to the solid-liquid separation chamber, and the floating fine particle flocs 22) in the mixed liquid float,
It is removed from the solid-liquid separation chamber by the scraping arm 20), and the huge flocs of sedimentable fine particles are discharged from the sludge discharge port 19) provided at the bottom of the solid-liquid separation chamber, and recycled and reused as necessary. It The supernatant liquid 21) is taken out of the system through a supernatant liquid outlet provided below the liquid surface of the solid-liquid separation chamber.

The aggregation method of the present invention uses the above-mentioned aggregating apparatus to separate the sedimentable fine particles and the supernatant in the liquid to be treated, when the fine particle concentration is low (10 ppm or less), an aggregating aid. By adding a large number of fine coagulation aids between the fine particles intended to be removed by adding, the effect of collision between the target fine particles (including the coagulation aid) is enhanced and the floc forming ability is enhanced. Is the way. The sludge (including the coagulation aid) that has been coagulated and concentrated by adding the coagulation aid is circulated and reused, and it is not necessary to add the coagulation aid to the washing wastewater and the waste sludge from the rapid filtration tank with a high concentration of fine particles.

Set the flow rate of the mixed solution (processing solution and injection solution) in the mixing tube to 10 <
Re <10 ⁵ and the flow rate of the injection liquid in the injection pipe are maintained at 5 <Re <10 ⁴ , and both liquids are brought into contact in the mixing pipe to almost complete the aggregation and separation action.

The liquid to be treated by the aggregating apparatus of the present invention is river water, groundwater, lake water, industrial / agricultural water, underground water, biological / physical chemical treated water, water purification plant drainage (discharged from a water purification plant The water used for washing the filtering pond and the sludge in the sedimentation pond) is called the liquid to be treated.

As the injection liquid, 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.) are used. When the electrolyte concentration of the liquid to be treated is low and does not differ from the electrolyte concentration of the injecting liquid, the electrolyte is added to the liquid to be treated or an aqueous solution containing the electrolyte as the injecting liquid, for example, an alkaline earth metal salt aqueous solution, an alkali metal. It is also possible to use an aqueous salt solution, a polymer flocculant, an Fe ++++, or an Al ++++ aqueous solution.

The coagulant added when the concentration of fine particles in the liquid to be treated is low is diatomaceous earth, bone charcoal powder, carbon powder (coal, coconut charcoal, activated carbon), magnesium carbonate powder, calcium phosphate powder, mica, feldspar, white clay, ceramics. Stone, talc, bentonite, kaolin, clay, kaolin, dolomite, magnesia, magnesium silicate, chrome, chrome magnesia, magnesia chrome alumina, silica, wax stone, titanium oxide, aluminum It is a fine powder of ceramic raw materials such as acid-lime, siliceous dicalcium, spinel, and zircon, finely pulverized fibers, and fine powder of a water-insoluble organic substance.

By installing porous materials (perforated plates) with a hole diameter of 0.5 to 8 mm in multiple stages in the annular part of the mixing tube, the liquid that has penetrated the holes of the porous materials (porous plates) at the discharge port downstream of the porous materials. However, the coagulation / separation performance does not deteriorate even if the lengths of the mixing tube and the injection tube are shortened, so that the coagulation device can be downsized.

The present invention will be described below with reference to the accompanying drawings. First
The figure shows an example of a flocculation device of the present invention, which is a vertical device. In the aggregating 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 a plurality of mixing tubes 5) (two are shown in FIG. 1) are provided in the dispersion chamber, one end of the mixing tube 5 having both ends opened is provided in the dispersion chamber as a supply port for the liquid to be treated, and the other end is Mixing pipe discharge port 15) that directly discharges the agglomerates into the solid-liquid separation chamber 4), injection pipes 6) to a plurality of mixing pipes, injection liquid supply pipe central axis 11) injection pipe central axis 12) mixing tube central axis 13) FIG. 13 is a view of an apparatus in which central axes are united (not necessarily required if a porous material is provided) and provided one by one. The injection pipe discharge port 14) opens toward the downstream 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) supplied in a laminar flow state from the injection pipe discharge port 14) through the porous material 16) and the mixing pipe. And the injection pipe, the laminar flow of the liquid to be treated flowing into the single pipe portion 18) of the mixing pipe downstream of the outlet of the injection pipe flows in contact with the liquid to be treated at the interface. The violent collision is repeated between the fine particles of and the huge particles are formed while passing through the mixing tube. The flocs that have settled are discharged from the sludge discharge port 19). The treated liquid supply ports of the plurality of mixing pipes are maintained at the same water level to equalize the inflow water amount of each mixing pipe. The number of mixing tubes depends on the total amount of the mixed solution 7) of the amount of liquid to be treated and the amount of injection liquid, and the flow rate passing through each mixing tube.
Decide to keep 10 <Re <10 ⁵ . The flow rate of the injection liquid in the injection pipe is also maintained at 5 <Re <10 ⁴ .

The solid-liquid separation performance of the present invention is high, because the fine particles of the liquid to be treated are washed in contact with the injecting liquid, and if the difference in the electrolyte concentration of both liquids is large, the decrease in the counter power generation level is caused between the fine particles. This is because it violently agglomerates and the mixed agglomeration is repeated to form huge flocs toward the downstream of the mixing tube. In general, when the difference in the electrolyte (ion) concentration between the two solutions is large, the cohesive force between the agglomerated fine particles and the floc particles seems to be strong. Desirably, if the difference in electrolyte concentration between the injecting liquid and the liquid to be treated is 0.1 mg / l or more, flocs are easily formed, and if it is 10 mg / l or more, the floc forming ability is strong.

The liquid to be treated with a low concentration of pollutants often has a distance between fine particles of 100 Å or more.If the distance between particles is greater than 100 Å, the number of collisions between particles is small and the block is small, resulting in agglomeration performance. Markedly reduced. Therefore, a coagulation aid having a large specific gravity with a diameter around the diameter of the particles in the liquid to be treated, and sludge (including the coagulation aid) that has been coagulated and separated is added as a coagulation aid and reused in circulation. The amount of addition is 10 to 1 × 10 ⁵ mg / l added to the liquid to be treated to enhance the collision effect to form huge flocs for aggregation and separation. Below 10 mg / l, the cohesive effect is not the prefectural capital. 1 × 10
^{At 5} mg / l and above, the effects just added do not appear.

The porous material (16) mounted on the annular portion of the mixing tube changes the hole diameter of the porous material depending on the diameter of the fine particles in the liquid to be treated. The solid particles of 1 mm or more in the liquid to be treated are removed with an inexpensive filter, the fine particle diameter here is 1 m.
m to 0.1 micron. In order to mount the porous material and reduce the size of the aggregating apparatus, it is necessary that the liquid to be treated that has passed through each hole of the porous material has a constant velocity as much as possible. Porous materials are antibacterial granules with a diameter of 0.01 to 5 mm, metal with a hole diameter of 0.001 to 8 mm, inorganic, polymeric resin porous plates, woven fabrics, knitted fabrics, non-woven fabrics, nets, sponges ) These materials may be used alone or in combination in layers. It is desirable to set the loading height of the porous material to 0.1 to 500 mm and the pressure loss to 0.01 to 10,000 mm at an average velocity of 1 mm / sec in the tap water pipe. If the pressure loss is 0.01 mm or less, there is little rectification effect, and if it is 10,000 mm or more, the required power is large and it is uneconomical.

Example -1 papermaking wastewater BOD250ppm, process water pipe that biological treatment of 1500 m ³ / day for COD230ppm is BOD5ppm, COD13ppm, SS6ppm, an electrolyte concentration 420 ppm. This treatment liquid is sand filtered (average filtration rate
4m / hr) is treated and used as recycled water. On the other hand, 50 ppm diatomaceous earth (average particle diameter 3.5 μm) was added to the above biological treatment liquid, and 1500 m ³ / day and 100 ³ / day of the injecting liquid were supplied to the liquid supply inlet of the liquid to be treated of the flocculating apparatus of FIG. 1 of the present invention. , The supernatant liquid was removed from the bottom of the solid-liquid separation chamber 30 cm below the water surface, and the settling fine particles were removed from the bottom of the solid-liquid separation chamber, and the removed sludge (sludge concentration 3.7%)
Was added to the biological treatment solution as diatomaceous earth and reused by circulation.
The aggregator consists of a mixing pipe (diameter 120 mm, length 1800 mm) and an injection pipe (diameter 25 mm, length 1300 mm) as one set 64
Two sets (4 rows x 16) / set were arranged and installed in two dispersion chambers, and the dispersion chamber water level was set 45 mm above the solid-liquid separation chamber water level.

Table 1 shows the treatment results of the sand filtration treated water and the treated water of the flocculating device of the present invention.

Example-2 River water, KMnO ₄ consumption 3.5 ppm, turbidity 73.6 degrees General bacteria 874
(Piece / ml), 200 m ³ / day of a mixed solution having bentonite of 30 ppm added to a chromaticity of 1.4 was used for the flocculating apparatus of the present invention [12 tubes (4 rows × 3 tubes) combining the same mixing tube and injection tube as in Example-1] To the dispersion chamber equipped with the. The water level in the dispersion chamber was set 50 mm above the water level in the solid-liquid separation chamber. The sedimentable fine particles were discharged from the bottom of the solid-liquid separation, and the discharged sludge was added as bentonite to the liquid to be treated (river water) and reused by circulation. The quality of treated water is the quality of the treated water (A) discharged from 25 cm below the water surface of the solid-liquid separation chamber, and the river water is the quality of the treated water (B) obtained by filtering the sand layer at a slow speed of 4 to 5 m / day. Table 3 shows the sludge concentration when the river water was collected in a cylinder and the sludge settled and concentrated, and the sludge concentration of (A), and the filter medium for slow sand filtration is shown in Table-2.

Table-2 Sand diameter mm Thickness mm Fine sand 0.2 to 0.4 800 Coarse sand 3.2 150 Fine gravel 5 to 9 140 〃 11 to 18 140 Cobblestone 22 to 31 250 Table-3 River water A B Turbidity 73.6 0.3 0 Color 1.4 0 0 KMnO ₄ Consumption ppm 3.5 1.33 1.13 General bacteria / ml 874 14 16 Sludge concentration ppm Settling time 1 min −5980 −24 hr 3670 − −Example-3 Washing drainage from rapid filtration pond of river water purification plant On the other hand, the same flocculating device as in Example 1 of the present invention is used for sedimentation concentration. Ca + + 5ppm added to filter pond cleaning wastewater, solid load
Table 4 shows a comparison of the concentration of concentrated sludge when supplied at 250 kg / m ² days and the change with time of sludge collected in a graduated cylinder. EFFECTS OF THE INVENTION In the aggregation method of the present invention, the electrolyte in the liquid to be treated can be used as the aggregating liquid of the fine particles in the liquid to be treated, so that the drug cost can be reduced.

In the coagulation method of the present invention, an alkali metal salt or an alkaline earth metal salt can be added to the liquid to be treated as a coagulant, and since the concentration thereof is low, there is no concern about clean water or environmental pollution.

Even if the concentration of fine particles in the liquid to be treated is low, inorganic fine particles having no eluate can be added as an aggregating aid to enhance the aggregating effect. Moreover, even if sludge (including a coagulation aid) that has been sedimented and concentrated is reused as a coagulation aid, the same coagulation effect as when using the coagulation aid alone is obtained, and SS in the treated water has the same water quality as that of the slow filtration. Can be obtained.

Since the solid load and the amount of treated water are large, the precipitation tank and the filtration tank can be downsized, and the same quality of water as the slow filtration tank can be obtained.

Since the flocculating device of the present invention forms a huge floc in the mixing tube only by contacting the injection liquid and the liquid to be treated, a power for collision and a floc growth chamber are unnecessary. Since the interface between the coagulated sludge in the solid-liquid separation chamber and the supernatant liquid is distinct, it can be automatically drawn out at a speed commensurate with the sedimentation and sedimentation speed, which facilitates operation management.

[Brief description of drawings]

FIG. 1 is a sectional view of the aggregating apparatus of the present invention. FIG. 2 is a cross-sectional view in which the discharge ports of the injection pipe are opened in multiple stages and the injection pipe and the mixing pipe are loaded with a porous material. 1: 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, 10 : Injection liquid 11: Injection liquid supply pipe central axis, 12: Injection pipe central axis, 13: Mixing pipe central axis, 14: Injection pipe discharge port, 15: Mixing pipe discharge port, 16: Porous material, 17: Annular part , 18: Single pipe part, 19: Sludge discharge port, 20: Scrape arm, 21: Supernatant liquid, 22: Floating fine particle flock

Claims (4)

(57) [Claims] 1. A liquid supply chamber 1) and a solid-liquid separation chamber 4),
A dispersion chamber 3) for dispersing the liquid 2) to be treated is provided in the liquid supply chamber, and one or a plurality of mixing pipes 5) having one end open to the dispersion chamber and the other end opened to a solid-liquid separation chamber, and the mixing is further performed. Injection liquid into tube 10)
Using an aggregating device having a structure in which one or a plurality of injection pipes 6) for injecting the liquid are provided, the injection liquid and the liquid to be treated are brought into contact with each other in a laminar flow state, so that the treated liquid contains polluted fine particles and a supernatant liquid. When separating into, the coagulation aid in the liquid to be treated is 30 to 1 × 10 ⁵ mg / l
An aggregating method for separating fine particles causing pollution from the liquid to be treated from the liquid to be treated and the upper liquid. 2. The agglutination method according to claim 1, wherein an electrolyte is added to the liquid to be treated. 3. The coagulation method according to claim 1, wherein sludge (including a coagulation aid) which has been coagulated and separated is added to the liquid to be treated and circulated. 4. The aggregating apparatus according to claim 1, wherein the porous material 16) is attached to the annular portion 17) of the mixing tube.