JP2552542B2 - Solid-liquid separation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to industrial wastewater, night soil, sewage, and biological treatment water, brewing waste liquid, brewing liquid, dredging liquid, dredging containing fine particles such as dredged bottom mud. The present invention relates to a solid-liquid separation method for aggregating and separating fine particles [microorganisms, algae, plankton, etc.] from a liquid.

[Prior Art] In biological treatment of contaminated wastewater, high concentration treatment of activated sludge that prevents deterioration of treated water quality due to occurrence of bulking, improves treated water quality, reduces excess sludge, and improves treatment capacity. It was impossible to continue operating the law.

In the case of the culture solution and the fermentation solution, in which the addition of the flocculant is preferred,
When separating microorganisms, high-grade separators that require enormous equipment costs are used. In addition, the conventional settling tanks were too low-performance to remove dredging sludge, fine particles in lakes and seawater, and phytoplankton in vast areas.

[Problems to be Solved by the Invention] The agglomerator and the solid-liquid separator previously proposed by the present inventor contain fine particles by contacting the sludge liquid containing fine particles with the injection liquid in the mixing pipe of these devices. The fine particles in the sludge liquid are aggregated and separated, but at the interface where the two liquids contact, there is a difference in the electrolyte concentration between the injected liquid washed fine particles and the unwashed fine particles, resulting in a difference in the surface potential value. , It will be a collision with suction. When the liquid discharged from the injection pipe flows in a laminar flow in the mixing pipe, the thickness of the interface becomes thin, the occurrence of vortex flow and disturbance is suppressed, and the solid-liquid separation performance is improved. To obtain a laminar flow, it is necessary to lengthen the injection pipe length and the mixing pipe length. There was a drawback that the equipment cost would increase if the pipe length was increased.

[Means for Solving the Problem] As a result of earnest research to solve such a drawback, the present inventor succeeded in improving the previously proposed solid-liquid separation method.

One of the characteristics of the solid-liquid separation method of the present invention is that, unlike the invention of the prior application, the separated fine particles are added to the injection liquid [for example, the electrolyte concentration is low] having a large difference from the electrolyte concentration of the fine particle-containing sludge liquid. The surface potential of the fine particles in the mixed injection liquid rises in an instant, so the mixed injection liquid containing the fine particles is mixed with the sludge liquid containing the fine particles having a low surface potential in the mixing pipe. By contacting
The fine particles in the sludge liquid containing fine particles aggregate to form huge flocs.

Fine particles added to the mixed injection liquid different from the electrolyte concentration of the fine particle-containing sludge liquid in the mixing tube, the value of the surface potential due to the electrolyte concentration in the fine particle-containing sludge liquid will be in contact with different fine particles, Suction aggregation easily occurs between the two fine particle groups. When contacting the conventional injection liquid and sludge liquid containing fine particles, in order to obtain fine particles with different surface potential values from the fine particles in the sludge liquid containing fine particles in contact with the injection liquid, It is an absolute requirement to form washed fine particles and unwashed fine particles (obtain fine particles having different surface potential values) at the interface of the particles in contact with the injection liquid. Therefore, it is necessary to continuously form an interface of a thin film of 0.1 to several tens of microns formed between two particles.
Therefore, no disturbance of the interface or generation of eddy current is allowed.
In order to obtain such a laminar flow, the mixing pipe length had to be 100 times as long as the diameter, or a porous material having a diameter of 0.005 to 3 mm had to be attached to the injection pipe.

The method of the present invention, the injection liquid having a large concentration difference with the electrolyte of the fine particle-containing sludge, just by adding fine particles in advance, the fine particles having a large difference with the surface potential value of the fine particles of the fine particle-containing sludge liquid Can be obtained. (Injection liquid containing the fine particles is referred to as “mixed injection liquid” in the present invention.) Sludge liquid containing fine particles and mixed injection liquid are mixed in a mixing pipe.
Since giant flocs can be obtained even when mixed at an interface with a thickness of 0.1 to several thousand microns, the length of the mixed injection liquid supply pipe, the length of the injection pipe injected into the mixing pipe, and the length of the mixing pipe can be shortened. Since a thick film may be used for the contact at the interface, the flow rate between the injection tube and the mixing tube can be increased several times or more. It was only necessary to attach a perforated plate with a pore size of 0.3 mm or more to the injection pipe in layers, and it became possible to circulate a part of the biologically treated water containing much SS.

In the solid-liquid separation method of the present invention, the flow rate of the mixed liquid (fine particle-containing sludge liquid and injection liquid) in the mixing pipe is set to 10 <Re <5 × 10 ⁵ ,
The flow rate of the mixed injection liquid in the injection pipe is maintained at 5 <Re <5 × 10 ⁴ , and both liquids are brought into contact with each other in the mixing pipe to almost complete the aggregation action.

The sludge liquid containing fine particles to be added to the injecting solution of the present invention and the fine particles to be treated by the solid-liquid separation device is a culture growth liquid, brewing waste liquid, dredging sludge [algae (diatoms, cyanobacteria, green algae, flagellates) microorganisms and them. Dead sea urchins and other organic and inorganic substances], lake water with a lot of phytoplankton generated due to eutrophication, and sea water, lake water containing actinomycetes of musty odor source, red tide flagella, and sea water Settled sediment sludge, industrial wastewater (including livestock waste) and its biologically treated water, domestic wastewater and its biologically treated water, night soil and its biologically treated water, and / or sewage and its biologically treated water, and all of the above liquids. SS.

The injection liquid is biological treatment supernatant, physicochemical treatment supernatant, low-concentration contaminated industrial wastewater, seawater, tap water, distilled water, irrigation water and / or industrial water (lakes, river water, groundwater, etc.). To be Further, as the injection liquid, an aqueous solution containing a coagulant, for example, a metal coagulant (aluminum salt, iron salt, activated silicic acid, magnesium salt, calcium salt) aqueous solution, an alkali metal salt aqueous solution, or a polymer coagulant aqueous solution can be used. .

In the apparatus used in the present invention, the solid-liquid separation chamber means a room for sedimentation / separation / concentration for flocculating flocs (see FIG. 1) and a room for flotation / concentration for flotation / concentration (see FIG. 2). As expected.

The apparatus used in the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an example of a solid-liquid separation device used in the present invention. In the solid-liquid separator, the dispersion chamber (2) is provided in the liquid supply chamber to which the fine particle-containing sludge liquid (1) is supplied. One or a plurality of mixing pipes (4) (two are shown in FIG. 1) are provided in the dispersion chamber, one end of the mixing pipe (4) having both ends opened is provided in the dispersion chamber, and a supply port for sludge liquid containing fine particles ( 13) and
The other end is a mixing pipe discharge port (15) for directly discharging the agglomerates to the solid-liquid separation chamber (3), and a plurality of mixed injection liquid supply pipes (1) for supplying the mixed injection liquid (6) to which fine particles are added ( 1
FIG. 1 is a view of an apparatus in which 1) is provided in an injection pipe (5), and a plurality of mixing pipes are provided with one injection pipe each having its central axis united.

The injection pipe discharge port (14) opens toward the downstream of the mixing pipe. A wall (12) is provided between the dispersion chamber and the solid-liquid separation chamber so that the flow of the mixed injection liquid (6) supplied from the injection pipe discharge port and the annular portion (17) to the single pipe portion (18). The sludge liquid (1) containing fine particles that flows into (see FIG. 3) flows in contact with each other, and at the interface, the violent collision between the fine particles of the sludge liquid containing fine particles and the fine particles of the mixed injection liquid. Is repeated, and huge flocs are formed while passing through the mixing tube. The fine particle-containing sludge liquid supply ports of a 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 pipes is determined so that the total amount of the mixed liquid (7) including the sludge liquid amount containing fine particles and the injection liquid amount is maintained so that the flow velocity passing through each mixing pipe is 10 <Re <5 × 10 ⁵ . The flow rate of the injection liquid in the injection pipe is also 5 <Re <5 × 10 ⁴
To hold.

FIG. 2 shows an example of an apparatus for treating floating phytoplankton as dredging sludge, which uses a floating solid-liquid separation chamber (3) as a solid-liquid separation chamber. The arrangement of the mixed injection liquid supply pipe (11) equipped with the perforated plate (16), the mixing pipe (4) and the injection pipe (5), and the flow velocity in the mixing pipe and in the injection pipe are within the same range as in FIG. In order to separate the giant flocs from the mixed liquid (7) discharged from the mixing pipe, the mixed liquid supplied to the buoyant solid-liquid separation chamber is guided to the connecting pipe (22) and is an outer cylinder of the solid-liquid separation chamber. Supply to. The giant flocs are concentrated while being swirl-floated and discharged from the top of the solid-liquid separation chamber as dredging sludge (10), and the supernatant liquid (8) is discharged from the central cylinder at the bottom of the floating solid-liquid separation chamber, Diffuse into the dredging water body (lake or sea).

FIG. 3 is a view in which the central axis (19) of the mixed injection liquid supply pipe (11) equipped with the perforated plate (16) is united with the injection pipe central axis (20) and the mixing tube central axis (21). .

The longer the length of the injection tube, the greater the ability to form flocs,
It is not easily affected by the water quality of the injection liquid, the shape of the pipe, and the injection method.
The pipe length is from the mixed liquid supply port to the injection liquid supply port of the perforated plate attached to the injection pipe or the discharge port of the filter injection pipe. The pipe length is preferably 5-100 of the injection pipe diameter (square pipe: equivalent diameter)
Double is better. Flock formation is not possible if it is 5 times or less. Even if the diameter of the injection pipe is 100 times or more, there is no problem in aggregating, but the solid-liquid separation device becomes huge, which is not economical.

If the flow velocity in the mixing tube is Re> 5 × 10 ⁵ , no flocs will form. If Re <5 × 10 ⁵ , flock will form. If 10> Re, the processing amount of the mixing tube per pipe is small and the processing cost is high. Even if the formed flocs are once destroyed when the flow rate in the mixing tube becomes 10 ⁴ <Re <5 × 10 ⁵ , they are formed if they are kept at Re <5 × 10 ⁵ . If the ejection speed of the injection liquid in or from the injection pipe is Re> 5 × 10 ⁴ , no flocs are formed.

If Re <5 × 10 ⁴ is maintained, flock growth is promoted. If Re <5, the treatment amount of the injection pipe per one is small, and the treatment cost becomes large.

The amount of the mixed injection liquid is 200% or less, preferably 30 to 1%, with respect to the sludge liquid containing fine particles. If it is less than 1%, the aggregating effect is low, and if it is more than 200%, the floc forming ability is not changed. If it exceeds 200%, the load on the solid-liquid separation chamber is too large, and the effect of increasing the injection liquid cannot be recognized.

The solid-liquid separation performance is improved because the fine particles in the sludge liquid containing fine particles come into contact with the fine particles added to the mixed injection liquid having different electrolyte concentrations, and the two (0.1 to 5) × 10 ^-3 mm Since there is a difference in electrolyte concentration between fine particles,
The decrease in repulsive potential energy causes a violent agglomeration action between the fine particles, and the agglomeration action of mixing is repeated to form a giant floc toward the downstream side of the mixing tube. This is due to the addition of powerful cohesive properties other than the cohesive properties of sludge. Therefore, even bulking sludge will form huge flocs.

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 electrolyte concentration difference between the mixed injection liquid and the sludge liquid containing fine particles is 1 mg / l or more, flocs are easily formed, and if it is 10 mg / l or more, the floc forming ability is strong. Flock is formed even at 2 × 10 ⁵ mg / l or more, but the drug cost is large and it is not economical.

The amount of fine particles added to the mixed injection liquid is 1 to 200% of the amount of fine particles in the sludge liquid containing fine particles. Desirably 3 to 1
It is 00%. If it is less than 1%, the floc forming ability is low, and if it is more than 200%, the coagulation facility, the mixing facility for added fine particles and the solid-liquid separation device become large. Generally, fine particles of the same quality that have been aggregated and separated are circulated and used, but when different types of fine particles are used, there is a device that responds to changes in the electrolyte concentration of the mixed injection liquid.

Example 1 An example of solid-liquid separation treatment of sludge (MLSS4120 mg /) obtained from the final aeration tank of an activated sludge facility that biologically treats pulp paper wastewater is shown. The equipment used in this method is
It is a seed.

Conventional device (device described in Japanese Patent Application No. 63-155624) A) Precipitation tank diameter 0.505 m, volume 0.4 m ³ (0.2 m ² × 2 m) test precipitation tank with solid-liquid separation chamber (diameter 0.2 m A device with a structure in which x 1.8 m) is installed.

In the solid-liquid separation chamber, an injection pipe (40 mm x 1000 mm) was equipped with a porous material propylene non-woven fabric (thickness 10 mm and 1080 g / m ² with a thickness of 45 mm) and a mixing pipe (diameter 60 mm, single pipe part length 600 mm annular part length 1000 mm).

B) It has a settling tank and a solid-liquid separation chamber of the same size as described above, and instead of a porous material in the injection pipe, a perforated plate (a stainless steel plate having a thickness of 1 mm has a hole diameter of 0.8 mm and 52 holes) (3 holes with a diameter of 3 mm and 2 plates are assembled in layers at intervals of 4 mm) are installed at a position 800 mm upstream from the inlet of the injection pipe, and the central axis of the injection tube and the central axis of the mixing tube are united. The device that was installed.

 Two types of devices, conventional devices A and B, were operated under the following conditions.

a) The activated sludge (MLSS4 120 mg /) supplied was 6 m ³ / day, and the injection liquid was 1 m ³ / day.

b) Activated sludge (MLSS4 120mg /) 6m ³ / day for mixed injection liquid 1m ³ / day [The composition of the mixed injection liquid is returned sludge (MLSS15100m
g /) 0.24m ³ / day mixed in a ratio of infusate 0.76 m ³ / day against] and the. The returned sludge was 1.64 m ³ / day for both a) and b).

 The injection liquid used was as follows.

B) Tap water a), b) Discharged water (Na + 220mg /) 40% tap water 60% mixed solution b), c) Discharged water (Na + 220mg /) in Ca
++ 10mg / was added to the solution, and it was necessary to stop the supply of activated sludge and the injection liquid to the solid-liquid separation device and the withdrawal of sludge from the settling tank to lower the sludge interface in the settling tank and double the concentration. Time and SS of discharged water
Table 1 shows the results of measuring the degree of clogging of the perforated plate and the porous material of the injection pipe due to the pressure loss after operating for 6 hours.

Defective: Flock is formed and liquid cannot be passed for 3 hours or more. A-
b) Inoperable / Clogged after 3 minutes of porous material. B-a) Unmeasurable, 10% coagulation of supplied sludge is impossible.

Example 2 An example in which water-bloom-contaminated water from a brackish water canal is subjected to floating treatment is shown. The apparatus used was a solid-liquid separation apparatus of the same type as the solid-liquid separation tank in FIG. 2, and the same mixing tube and injection tube as in Example 1-B were used. A perforated plate [a stainless steel plate with a thickness of 1 mm has a hole diameter of 1.2 mm (36 pieces) (downstream side) and a hole diameter of 5 mm (9 pieces) (upstream side) is opened in the injection tube, and two plates are assembled in layers at 6 mm intervals] Was installed at an upstream position of 800 mm from the center, and the central axis of the injection tube and the central axis of the mixing tube were united and installed. As the injecting solution, a mixed solution of the treated water of the present invention (COD20.6 mg /, SS1.85 mg /, Cl148 mg /) and river water (COD5.2 mg /, SS4.8 mg /, Cl16 mg /) in a ratio of 0.5: 1 is used. did. The river water was previously filtered with a 0.6 mm screen. A water-contaminated water was treated at a rate of 1.5 m ³ / day of injection solution for 12 m ³ / day. Algae sludge water 12m ³ / day, 15m ³ / day mixed injection liquid (in addition to the injection liquid 500 of 2700mg / algae sludge 100 floated and separated in A, 500, stirred and mixed, the whole sludge obtained by filtration is further injected liquid 50
B treated at a rate of 1.5 m ³ / day (added to 0). The SS and pressure loss (pressure drop during 8 hours from the start of operation to the stop of operation) in the treatment liquids of A and B were obtained.

In the case of B, which used the mixed injection liquid containing the water-bloom sludge, the treated water quality did not deteriorate even if the amount of the water-polluted water supply was increased by 25% of that of A.

[Effect of the Invention] The coagulation method of the present invention can add fine particles in sludge liquid containing fine particles to an injecting liquid having a large difference from the electrolyte concentration in the sludge liquid containing fine particles by simply adding fine particles in the sludge liquid containing fine particles. Fine particles having a surface potential value different from that of the particles can be easily obtained in the mixed injection liquid.

When the mixed injection liquid containing the fine particles and the sludge liquid containing the fine particles were contacted in the mixing pipe at Re <5 × 10 ⁵ , the processing capacity per mixing pipe was enhanced several times.

[Brief description of drawings]

FIG. 1 is a sectional view of a solid-liquid separation device used in the present invention. FIG. 2 is a sectional view of the solid-liquid separation device (floating solid-liquid separation chamber) used in the present invention. FIG. 3 is a cross-sectional view in which the mixed injection liquid supply pipe equipped with the perforated plate used in the present invention, the injection pipe, and the central axes of the mixing pipe are completely united. 1 ... Sludge liquid containing fine particles, 2 ... Dispersion chamber, 3 ... Solid-liquid separation chamber, 4 ... Mixing pipe, 5 ... Injection pipe, 6 ... Mixed injection liquid, 7 ... Mixed liquid, 8 ... … Supernatant, 9 …… Concentrated sludge, 10
...... Floating concentrated sludge, 11 …… Mixed injection liquid supply pipe, 12 ……
Wall, 13 ... Sludge liquid supply port containing fine particles, 14 ... Injection pipe discharge port, 15 ... Mixing pipe discharge port, 16 ... Perforated plate, 17 ... Annular part, 18 ... Single pipe part, 19 ... … Mixed injection liquid supply pipe central axis, 20
…… Injection tube central axis, 21 …… Mixing tube central axis, 22 …… Connection tube

Claims (8)

(57) [Claims] 1. A dispersion chamber (2) for dispersing a sludge liquid (1) containing fine particles, and a solid-liquid separation chamber (3) for separating fine particles and a supernatant from the sludge. , One or more mixing pipes (4) having one end open to the dispersion chamber and the other end to the solid-liquid separation chamber are provided through the wall (12) of the dispersion chamber, and the injection liquid is injected into the mixing pipes. Using a solid-liquid separation device having a structure in which one or a plurality of injection pipes (5) for supplying the injection liquid and further one or a plurality of injection liquid supply pipes (11) for supplying the injection liquid to the injection pipes are included. Separation of fine particles and supernatant from sludge liquid is characterized by using a mixed injection liquid in which fine particles are added in advance as an injection liquid. Separation of fine particles and supernatant liquid from sludge liquid containing fine particles Solid-liquid separation method. 2. A dispersion chamber (2) for dispersing sludge liquid containing fine particles, one or a plurality of mixing pipes (4) having one end opened to the dispersion chamber and the other end having a wall (12) of the dispersion chamber. A structure in which one or a plurality of injection pipes (5) for injecting an injection liquid into the mixture are provided so as to penetrate therethrough and opened to the outside, and further one or a plurality of injection liquid supply pipes (11) are provided in the injection pipe. In separating the fine particles and the supernatant from the fine particle-containing sludge liquid using the solid-liquid separation device member having a fine particle content characterized by using a mixed injection liquid to which the fine particles are added in advance as the injection liquid A solid-liquid separation method for separating fine particles and a supernatant from sludge liquid. 3. The solid-liquid separation method according to claim 1, wherein the amount of the mixed injection liquid is 1 to 200% of the amount of the sludge liquid containing fine particles. 4. The difference between the electrolyte concentration in the mixed injection liquid and the electrolyte concentration in the sludge liquid containing fine particles is 1 mg / to 2 × 10 ⁵ mg /
The solid-liquid separation method according to claim 1 or 2, wherein 5. The solid-liquid separation method according to claim 1, wherein the amount of fine particles added to the mixed injection liquid is 1 to 200% of the amount of fine particles in the sludge liquid containing fine particles. 6. The solid-liquid separation method according to claim 1, wherein the electrolyte concentration in the mixed injection liquid is lower than the electrolyte concentration in the sludge liquid containing fine particles. 7. The solid-liquid separation method according to claim 1 or 2, wherein the electrolyte concentration in the mixed injection liquid is higher than the electrolyte concentration in the sludge liquid containing fine particles. 8. The solid-liquid separation method according to claim 1 or 2, wherein the mixed injection liquid has a composition in which the injection liquid is mixed with fine particles separated from sludge liquid containing fine particles in advance.