JP2001137865A - Method for separating insolubilized matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for separating insolubilized matter which is capable of obtaining clean filtrate for a long period by improving the affinity of the inorganic insolubilized matter precipitated by an insolubilization treatment of liquid to be treated to a filter medium, thereby enhancing the capturability by the filter medium and preventing the leakage of the insolubilized matter from the filter medium to execute filtration and separation efficiently. SOLUTION: The liquid 5 to be treated is introduced into an insolubilization vessel 1 where a flocculating agent or insolubilizing agent is added thereto to precipitate the inorganic insolubilized matter. The precipitated insolubilized matter is partly subjected to a separation of solid from the liquid in a settling vessel 3 or floating vessel 4 and thereafter or without subjecting the insolubilized matter to the separation of the solid from the liquid, an alkali metal salt 10 of a higher fatty acid is added thereto and the insolubilized matter is subjected to a filtration and separation treatment in a filter vessel 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insolubilized material separation method for insolubilizing a liquid to be treated, thereby precipitating an inorganic insoluble material, and filtering and separating the insoluble material.

[0002]

2. Description of the Related Art In waste water treatment, coagulation treatment is performed to remove impurities such as turbid and colloidal substances contained in a liquid to be treated. In this coagulation treatment, an inorganic coagulant is added to the liquid to be treated, and if necessary, a pH adjuster is added to adjust the pH.
There is a method in which the coagulant component is precipitated as an insolubilized substance by adjusting the concentration, and at this time, impurities are embodied in the insolubilized substance and removed. The insolubilized material thus precipitated is separated by settling,
After separation by solid-liquid separation such as flotation separation, or separation without filtration, separation is performed.

[0003] Apart from such agglomeration treatment, there is a neutralization treatment method in which when a liquid to be treated contains heavy metal ions, the solution is neutralized by adding an alkali to make the heavy metal ions insoluble. There is a method in which a heavy metal ion is insolubilized by adding an insolubilizing agent such as a sulfide or a phosphate in addition to the alkali, and the insolubilized material is separated by solid-liquid separation or by filtration without separation.

[0004] As a filtration device used for filtration and separation of such inorganic insolubilized materials, a filtration device having a filter layer filled with a particulate filter material such as sand or anthracite is used. Are used in two layers. In such a usual two-layer filtration device, the anthracite filled in the upper layer has a particle size of 0.7 to 0.7.
1.4 mm, the filling height is 300 to 500 mm, the lower sand layer has a particle size of 0.35 to 0.7 mm, and the filling height is 300
Although it is about 500 mm, a filter medium having a small particle size is used in order to obtain treated water as clear as possible. The suspended matter is trapped in the gap between the filter medium particles. However, when the filter medium is small, the gap is narrowed. Therefore, the suspended matter is reduced, the clogging occurs early, and the backwashing must be constantly performed. As a result, the operation time was reduced, and the intended water volume could not be obtained in some cases. Therefore, in general, a combination of sand having a particle size of 0.45 mm and anthracite having a particle size of 0.7 mm is often applied.

However, when there is no affinity between the trapped turbid substance and the filter medium, the turbid substance may not pass through the filter medium but pass through the filter medium, and the target clear treated water may not be obtained. In such a case, the problem may be solved by reducing the particle size of the filter medium, but there is a problem that the trapped amount is reduced as described above. Also, even if the filter media particle size is reduced,
If the affinity of the turbid filter media is low, slight pressure changes,
Even if the flow rate changes, the liquid will pass through the filter medium gap, and the physical properties of the turbid substance may have a significant effect.

Hitherto, in the filtration separation, no consideration has been given to the affinity between the filter medium and the material to be filtered. on the other hand,
In a method of adding an inorganic coagulant to perform coagulation treatment and separating precipitates by pressure flotation, an alkali metal salt of a higher fatty acid is added to increase the stability of flocs and efficiently perform pressure flotation. A method has been proposed (Japanese Unexamined Patent Publication No.
No. 6313). However, in this method, the higher fatty acid alkali metal salt is used to increase the stability of the floc in the flotation under pressure, and the affinity in the subsequent filtration separation is not considered.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the affinity of an inorganic insolubilized substance precipitated by insolubilizing a liquid to be treated with a filter medium to increase the trapping property of the filter medium, and to improve the insolubilized filter medium. The present invention proposes a method for separating an insolubilized substance capable of preventing leakage from water and efficiently performing filtration separation to obtain a clear filtrate over a long period of time.

[0008]

The present invention relates to the following method for separating insolubles. (1) The solution to be treated is insolubilized to precipitate an inorganic insolubilized substance, and after a part of the precipitated insolubilized substance is subjected to solid-liquid separation or without solid-liquid separation, a higher fatty acid alkali metal salt is added. A method for separating an insolubilized substance, comprising performing filtration separation. (2) The method according to the above (1), wherein the insolubilization treatment of the liquid to be treated is an aggregation treatment in which an insolubilized substance is precipitated by adding an aggregating agent. (3) The insolubilization treatment of the liquid to be treated is a treatment for insolubilizing the components in the liquid to be treated by adding an insolubilizing agent.
The described method.

In the present invention, the liquid to be treated is a liquid to be subjected to an insolubilization treatment such as an aggregation treatment and a neutralization treatment. The liquid to be treated to be subjected to the coagulation treatment is a liquid containing impurities, such as suspensions, colloids, and organic substances, which are removed by the coagulation treatment with an inorganic coagulant. The liquid to be treated to be subjected to the neutralization treatment or the like is a liquid which contains impurity ions such as heavy metal ions and which precipitates as insolubilized substances by the addition of an insolubilizing agent such as an alkali. In addition to the alkali, a liquid containing impurity ions or the like which are insolubilized by the addition of another insolubilizing agent such as sulfide or phosphate may be used.

In the present invention, the insolubilization treatment includes, in addition to a treatment such as a coagulation treatment in which an added chemical is precipitated as an insolubilized material, and a treatment such as neutralization treatment in which aluminum, iron, manganese, and copper contained in the liquid to be treated are contained. In addition, there is a treatment in which impurities (including a complex) such as heavy metal ions such as zinc precipitate as insolubilized substances by adding an insolubilizing agent. The treatment for insolubilization by the addition of an insolubilizing agent is, in addition to the neutralization treatment by the addition of an alkali agent, the treatment of precipitation as an insoluble sulfide by the addition of sulfide, and the treatment of precipitation as an insoluble phosphate by the addition of phosphoric acid or a salt. And so on.

The inorganic flocculant used in the flocculation treatment includes a sulfuric acid band, basic aluminum chloride (PAC), iron chloride, iron sulfate and the like. Examples of the pH adjusting agent used together with these inorganic coagulants include alkali agents such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and acids such as hydrochloric acid and sulfuric acid. In the coagulation treatment, an inorganic coagulant is added to the liquid to be treated, and if necessary, a pH adjuster is added to optimize the pH.
And stir rapidly and slowly. This causes the components of the flocculant to precipitate as insolubilized substances such as hydroxides,
Flock is formed.

As the alkaline agent used for the neutralization treatment,
Examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, and sodium carbonate. Other insolubilizing agents include sulfides such as hydrogen sulfide and sodium sulfide, and phosphates such as sodium phosphate and potassium phosphate. In addition, it can be insolubilized using an oxidizing agent or an inorganic coagulant.

[0013] The insolubilization treatment using these insolubilizing agents includes:
By adding an insolubilizer to the liquid to be treated and reacting,
Impurities such as heavy metal ions contained in the liquid to be treated are precipitated as insolubilized substances such as hydroxides, sulfides and phosphates.
In the case of a complex ion, it may be insolubilized by being decomposed in combination with an oxidizing agent or the like. Aggregation can also be performed using an inorganic coagulant in combination.

The insolubilization treatment such as the above-mentioned coagulation treatment and neutralization treatment can be performed only by a chemical reaction, but the insolubilization can be promoted by adding operations such as heating, light irradiation, and ultrasonic treatment. When the insolubilized substance is precipitated by these insolubilization treatments, it is preferable to grow flocs to form large flocs, but it is not always necessary to grow flocs. An organic polymer flocculant may be added, but need not be added.

The insolubilized solution in which the inorganic insolubilized substance has been precipitated as described above may be added to the alkali metal salt of a higher fatty acid as it is and subjected to filtration and separation. However, prior to this, other solidification such as sedimentation separation and flotation separation may be performed. After separating the insolubilized product by the liquid separating means, the higher fatty acid alkali metal salt is added to perform the filtration separation, whereby the load in the filtration separation can be reduced. In the sedimentation separation, separation is performed by natural sedimentation by staying in a sedimentation tank. Floating separation is a method in which fine bubbles are usually attached to an insolubilized substance using a foaming agent or the like to separate them by floating, and a pressurized floating method using pressurized water is preferable. In addition, solid-liquid separation means such as centrifugation may be used.

In the present invention, after a part of the insolubilized product is subjected to solid-liquid separation or without the solid-liquid separation, a higher fatty acid alkali metal salt is added to the insolubilized solution to carry out filtration separation. As higher fatty acids, C ₈ -C ₂₂ , preferably C
Higher fatty acids, saturated or unsaturated ₁₂ -C ₂₀ and the like. Examples of the alkali metal salt include a sodium salt and a potassium salt. Such higher fatty acid alkali metal salt is added in an amount of 1/5 to 1/10 of the insolubilized amount by weight.
0, preferably about 1/10 to 1/30. If such higher fatty acid alkali metal salt is added before the insolubilization treatment, it will be taken into the insolubilized material.By adding it after the insolubilization treatment, the surface of the insolubilized material is modified to impart affinity to the filter medium. be able to. When a part of the insolubilized product is subjected to solid-liquid separation before filtration and separation, if added before solid-liquid separation, the higher fatty acid alkali metal salt is also separated. Therefore, the higher fatty acid alkali metal salt is added after solid-liquid separation. Thereby, the surface of the insolubilized material can be modified.

There is no particular limitation on the filtration device used for the filtration separation, but a filtration device using a particulate filter medium is preferred. As the granular filter media, those conventionally used, such as sand and anthracite, are used. In particular, two-layer filtration in which sand and anthracite are laminated is preferable. In this case, the anthracite filled in the upper layer has an average particle size of 0.7 to 1.4 mm, the filling height is 300 to 500 mm, and the lower sand layer has an average particle size of 0.35.
It is preferable that the filling height is 0.7 mm and the filling height is 300 mm to 500 mm.

By adding a higher fatty acid alkali metal salt to the insolubilized liquid or the solid-liquid separation liquid and performing filtration separation, the affinity of the insolubilized substance with the filter medium is improved, so that the insoluble substance is easily captured by the filter medium. Become. For this reason, even if the particle size of the filter medium is not reduced, the insolubles can be efficiently captured and the amount of the insolubles leaking out can be reduced, and a clear separated solution can be obtained.

Since filter media such as sand and anthracite have a high affinity for hydrophobic turbidity, when a wastewater containing oil, which is a typical hydrophobic substance, is filtered, the oil is strongly adsorbed to the filter media, and the filter media is backwashed. It cannot be ruled out by performing operations. Eventually, the solidification of the filter media, known as the mudball phenomenon, occurs. In the present invention, an organic substance having a hydrophobic group is adsorbed based on the idea that the surface of the insolubilized substance is made hydrophobic to increase the affinity for the filter medium. Since the insolubilized substance to be separated by filtration in the present invention contains a metal, the organic substance to be added is preferably a linear organic substance having one end hydrophobic and the other end having an affinity for the metal. If the above functional group reacts with or is adsorbed to the turbid metal part, the hydrophobic group at the other end remains on the liquid side, so that the insolubilized substance behaves like a hydrophobic substance and is also adsorbed to the filter medium. It is presumed that it will be easier.

[0020]

As described above, according to the present invention, the insolubilized substance is precipitated, and the higher fatty acid alkali metal salt is added to carry out the filtration and separation. The affinity of the insolubilized substance with the filter medium is improved to enhance the trapping property of the filter medium, and the insoluble substance is prevented from leaking out of the filter medium, and is efficiently separated by filtration to obtain a clear filtrate over a long period of time.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A to 1C are flowcharts showing an insolubilized matter separation method according to an embodiment. FIG. 1 (a)-
In (c), 1 is an insolubilization tank, 2 is a filtration tank, 3 is a sedimentation tank, and 4 is a floating tank.

In FIG. 1A, the liquid passage 5 to be treated is
, A coagulant or an insolubilizing agent is injected from the chemical injection path 6, and a pH adjuster or other chemicals are injected from the chemical injection path 7 if necessary, and the mixture is stirred by the stirrer 8 to perform an aggregation treatment.
Perform insolubilization such as neutralization. Chemical injection route 6 for coagulation treatment
By injecting a coagulant from the solution and injecting a pH adjuster from the chemical injection path 7 to cause a reaction, thereby precipitating an insolubilized substance mainly composed of a hydroxide of an inorganic salt as a coagulant component, and Flocs are formed by incorporating impurities such as suspensions, colloids, and organic substances. In the case of the neutralization treatment or other insolubilization treatment, an insolubilizing agent such as an alkali, a sulfide, a phosphate, or the like is injected from the chemical injection path 6, and a coagulant or other chemical is injected from the chemical injection path 7 if necessary. It reacts with heavy metal ions and the like in the treatment liquid to precipitate insolubles.

The insolubilized solution is added and mixed with a higher fatty acid alkali metal salt from the chemical injection line 10 while being sent from the transfer passage 9 to the filtration tank 2, introduced into the filtration tank 2, and subjected to filtration and separation. The filtration tank 2 is a two-layer filtration tank in which an upper layer is filled with anthracite as a large-diameter filter medium layer 11 and a lower layer is filled with sand as a small-diameter filter medium layer 12. The insolubilized solution to which the higher fatty acid alkali metal salt is added first removes most of the insolubilized substance in the large-diameter filter medium layer 11 and further removes the remaining insoluble substance in the small-diameter filter medium layer 12. At this time, since the insolubilized substance binds to the higher fatty acid alkali metal salt and has a high affinity for the filter medium, even if a filter medium having a large particle size is used, the insolubilized substance is highly trapped, preventing leakage from the filter medium layer. As a result, filtration and separation can be performed efficiently, and a clear filtrate can be obtained. The filtrate is discharged from the treatment water channel 13 as treated water.

In FIG. 1B, the insolubilized solution in the insolubilization tank 1 is settled and separated in the settling tank 3 and then filtered and separated in the filtration tank 2. In this case, the insolubilized liquid that has entered the sedimentation tank 3 from the transfer path 9a precipitates the insolubilized matter by natural settling, the sludge is discharged from the sludge discharge path 14, and the separated liquid is transferred to the transfer path 9b.
, The higher fatty acid alkali metal salt is added from the chemical injection path 10 during filtration to the filtration tank 2 to carry out filtration separation. When the higher fatty acid alkali metal salt is injected into the transfer path 9a from the chemical injection path 15,
Most of the higher fatty acid alkali metal salt is lost in the precipitation tank 3, but by injecting it from the chemical injection path 10, the affinity of the insolubilized substance flowing into the filtration tank 2 can be efficiently improved.

In FIG. 1C, the insolubilized solution in the insolubilization tank 1 is subjected to pressure flotation in the flotation tank 4 and then filtered and separated in the filtration tank 2. In this case, the pressurized water channel 1
When the insolubilized solution mixed by injecting pressurized water from 6 into the floating tank 4, fine bubbles generated by depressurization adhere to the insolubilized material and float to perform floating separation. The sludge that has floated is collected in the sludge collecting section 17 and discharged from the sludge passage 14.
While the separated liquid is sent from the transfer path 9b to the filtration tank 2, the chemical injection path 10
, A higher fatty acid alkali metal salt is added thereto, followed by filtration. When the higher fatty acid alkali metal salt is injected from the chemical injection path 18 into the transfer path 9a, most of the higher fatty acid alkali metal salt is lost in the floating tank 4, but is injected into the filtration tank 2 by injection from the chemical injection path 10. The affinity of the insolubilized substance can be efficiently improved.

The above-described processing of FIG. 1A is suitable for a case where the amount of insoluble matter is small, the processing of FIG. 1B is suitable for a case where a large amount of heavy insoluble matter is generated, and the processing of FIG. Suitable when a lot of light insolubilized substances are produced. When the filtered water is recovered and used, an activated carbon treatment or a microfiltration can be further provided at a later stage. When collecting as pure water, an ion exchange resin, a reverse osmosis membrane device, or the like can be installed. In these cases, the filtered water should be as clear as possible to prevent fouling.

In any of the treatments shown in FIGS. 1 (a) to 1 (c), since the higher fatty acid alkali metal salt is added to the insolubilized solution before filtration and separation, the liquid to be treated is separated from the inorganic solution precipitated in the insolubilization process. The affinity of the insolubilized substance with the filter medium is improved to increase the trapping property of the filter medium, the insoluble substance is prevented from leaking out of the filter medium, and the filtration is efficiently performed, whereby a clear filtrate can be obtained over a long period of time.

[0028]

Embodiments of the present invention will be described below. In the examples, the clarity of the processing solution was determined by the MF check method using a microfiltration membrane having a pore size of 0.45 μm manufactured by Millipore to filter 1 liter of sample water, and the filtration time was indicated in MF time (unit: [minute: second]). did.

Example 1, Comparative Example 1 Groundwater (pH 7.5, electric conductivity: 21) was used as the liquid to be treated.
mS / m, M alkalinity: 95 mg / l (as CaCO ₃ ), turbidity: 1.8 degrees, chromaticity: 12 degrees, Fe: 0.6
mg / l) and the treatment was performed by the method shown in FIG. In the insolubilization tank, chlorine 2 mg / l and liquid sulfuric acid band 10 mg /
l, and the treated water amount is 110 m ³ / hr, and the reaction time is 1
Aggregation treatment was performed for 0 minutes. In the insolubilized solution, 0.2 mg / l of an oleic acid-based complex soap was added as a higher fatty acid alkali metal salt (Example 1), and the case where it was not added (Comparative Example 1) was separated by filtration in a filtration tank. Was done. The filtration tank contains 3 anthracite particles with a particle size of 0.9 mm.
This was a two-layer filtration of an upper layer filled to a height of 50 mm and a lower layer filled to a height of 350 mm with sand having a particle size of 0.45 mm. Filtration was performed at LV 6.5 m / hr. MF of treatment liquid
Table 1 shows the filtration time by time (liquid temperature: 12 ° C., degree of vacuum: 67 kPa, filtration time of 1 liter of distilled water as a blank is 2 minutes and 04 seconds).

[0030]

[Table 1]

Example 2, Comparative Example 2 The effect of the addition position of the fatty acid soap in the method shown in FIG. The liquid to be treated is lake water (pH 7.8, electric conductivity: 12 mS / m, M alkalinity: 40 mg / l)
(As CaCO ₃ ), turbidity: 4.5 degrees, chromaticity: 20
(SS, 6.0 mg / l), polyaluminum chloride was added at 25 mg / l in the insolubilization tank, and the coagulation treatment was performed at a treatment water volume of 80 m ³ / hr for a reaction time of 10 minutes. A pressure levitation treatment was performed. In the pressure levitation treatment, pressurized water (350 kPa... Gauge pressure) was injected at a ratio of raw water / pressurized water = 10/2, and levitation separation was performed at a levitation LV of 7 m / hr. Filtration tank is sand layer 0.45mm, filling height 3
50mm, anthracite part 0.9mm, filling height 35
0 mm and LV 5 m / hr. The MF time depending on the amount of treated water when the fatty acid soap (oleic acid-based complex soap) is added at the chemical injection route 10 (Example 2) and when the fatty acid soap is added at the chemical injection route 18 (Comparative Example 2). Table 2 shows the difference between the liquid temperature of 15 ° C., the degree of vacuum of 67 kPa, and the filtration time of 1 liter of distilled water as a blank is 2 minutes 01 seconds.

[0032]

[Table 2]

From the results shown in Table 1, in Example 1 in which the higher fatty acid salt was added, the water quality at the level of distilled water could be ensured for 12 hours. In Comparative Example 1 in which the higher fatty acid salt was not added,
3 hours or less. Also, from the results in Table 2, Example 2 in which the higher fatty acid salt is added to the outlet side of the floating tank has a smaller amount of drug for a longer time than Comparative Example 2 in which the higher fatty acid salt is added to the inlet side of the floating tank. It can be seen that an excellent effect of filtration separation can be obtained.

[Brief description of the drawings]

1 (a) to 1 (c) are flow charts showing an insolubilized matter separation method according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insolubilization tank 2 Filtration tank 3 Precipitation tank 4 Floating tank 5 Liquid path to be processed 6, 7, 10, 15, 18 Chemical injection path 8 Agitator 9, 9a, 9b Transfer path 11 Large-diameter filter medium layer 12 Small-diameter filter medium layer 13 Treatment water passage 14 Drainage passage 16 Pressurized water passage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D037 AA01 AB08 BA02 BB07 CA02 CA08 CA14 4D038 AA02 AB60 AB66 AB68 AB69 AB79 AB80 BB01 BB04 BB07 BB13 BB17 BB18

Claims (3)

[Claims] 1. An insolubilizing treatment of a liquid to be treated to precipitate an inorganic insolubilized substance, and after adding a solid-liquid separation to a part of the precipitated insolubilized substance, or adding a higher fatty acid alkali metal salt without solid-liquid separation. And separating the solution by filtration. 2. The method according to claim 1, wherein the insolubilization treatment of the liquid to be treated is a coagulation treatment in which an insolubilized substance is precipitated by adding a coagulant. 3. The method according to claim 1, wherein the insolubilizing treatment of the liquid to be treated is a treatment for insolubilizing components in the liquid to be treated by adding an insolubilizing agent.