JP2007098301A - Method for continuously cleaning and discharging soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously clean contaminated soil by contamination, complex contamination or the like by oil, organic compound materials, heavy metals and its compounds at a low cost. <P>SOLUTION: This method comprises the followings: (i) a process of slurrying for preparing a contaminated soil slurry by preparing a mixed fluid by injecting water to contaminated soil and sucking the mixed fluid by a water ejector utilizing pressurized water as a driving source; (ii) a process of precipitation-separation for continuously preparing precipitated soil comprising soil particles precipitated and separated from a downward flow at the time of recovering an upward flow as contaminated water by continuously precipitating and separating the contaminated soil slurry and separating into the upward flow of diluted water containing lots of contaminants and the downward flow consisting of most of the soil particles; and (iii) a process of discharge having an extruder continuously discharging and transferring the precipitated soil to prepare cleaned soil. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a slurry is continuously made from contaminated soil and water, and then the slurry is continuously settled and separated, and then the sedimented and separated sediment is discharged and transferred to obtain washed soil. It relates to a cleaning and discharging method.

  In recent years, as a result of industrial activities, the presence of soil contaminated with oil, organic compounds, heavy metals and their compounds, and contaminated soil due to complex pollution has attracted attention as an environmental problem. The problem of soil contamination is that the existence of the contaminated soil itself is a problem, as well as water pollution of the water that has passed through the soil, air pollution due to the diffusion of harmful volatile substances from the soil, etc. It has a great negative effect.

  Soil remediation measures have been proposed as a method for avoiding such adverse environmental effects due to soil contamination. Examples thereof include excavation and disposal of contaminated soil, incineration processing of contaminated soil, chemical extraction processing of pollutants, or biodemetry. These methods are selected and implemented in consideration of the characteristics of pollutants, the nature of the contaminated soil, the environment, treatment costs and construction period, and the like.

  However, in reality, the above-described method has a major drawback. For example, in many cases, the excavation and disposal method of contaminated soil is merely transfer of pollutants, and environmental pollution spreads instead. Since the incineration method incinerates the soil, it requires enormous consumption of energy, and at the same time, the soil is altered by heat.

  In the soil cleaning treatment method, water or a cleaning agent is used. In the case of washing with water, in order to use, for example, a cyclone as described in Patent Document 1 to separate soil and contaminants, fine particles in the soil composition are also discarded together with the contaminants. For this reason, some tens of percent of the soil is discarded.

In the soil cleaning treatment, many cleaning methods using a cleaning agent are also disclosed.
In the method described in Patent Document 2, for example, for washing oil-contaminated soil, water corresponding to the mass of the soil and a nonionic surfactant are added and washed for 10 minutes. Next, for rinsing and washing after dehydration, the same amount of water as before is added and stirring and washing is performed for 10 minutes.

In the method described in Patent Document 3, for example, a soil cleaning agent 5 times the mass of the contaminated soil is added and stirred for 15 minutes. Next, it is dehydrated and further washed with water 3 times the mass of the soil.
In addition, as a method of washing contaminated soil with poorly water-soluble organic matter, after adding a nonionic surfactant to the wash water and washing it, an iron salt and a polymer flocculant are added to treat the contaminated water. Methods are also known.

  The use of such a cleaning agent and a method requiring a long processing time are economically disadvantageous. In addition, the chemical extraction treatment method leaves the possibility of further contamination of the soil with a cleaning agent or an extraction agent, and in biomedation, the work period is prolonged due to the delayed effect. Furthermore, in the conventional soil cleaning method, soil cleaning is performed by batch operation, and there is no known soil continuous cleaning and discharging method in which soil is slurried and then washed and discharged in a continuous operation. It was.

  As described above, there are many problems with the conventionally known soil cleaning methods, but the preconditions for soil treatment such as the types of pollutants in the contaminated soil and the contaminated environment may be complicated, so the cost of the soil Currently, a purification method is employed, and there is a demand for a soil purification method that can realize cost reduction.

JP 2003-251330 A JP 2003-1238 A JP 2003-119495 A

  The present invention has been made to solve the problems of the conventional methods as described above, and after making a slurry with contaminated soil and diluted water, the slurry is continuously settled and separated and continuously stabilized. In this way, the soil that has been purified and has almost the same composition as the contaminated soil and remains unaltered is recovered stably and at a high recovery rate, and the contaminated water containing the contaminant is treated with water and recovered. The purpose is to reduce the amount of water used by effectively circulating the used water as dilution water.

As a result of diligent research to solve the above-mentioned problems, the present inventor considers the influence on the environment, uses only water as a cleaning medium, dilutes contaminated soil with water, and creates a slurry. The slurry is continuously settled and separated, and the contaminated water containing most of the pollutants is separated, and the settled sediment is separated and settled at a target high washing rate and recovery rate through a stable operation. The inventors have found a method for obtaining the washing soil and have completed the present invention. The cleaning rate is the contaminant removal rate.
That is, the present invention is as follows.

(1) A soil continuous washing and discharging method comprising the following (a), (b), and (c).
(I) Mixing a mixture of contaminated soil composed of soil particles, contaminants and contained water and water injected to impart fluidity to the contaminated soil with a water ejector driven by pressure water. , A slurrying process that continuously creates a contaminated soil slurry using the injected water and pressure water as dilution water,

  (B) Injecting the contaminated soil slurry into the center of the sedimentation separation tank, and dividing the slurry into a downward flow mainly composed of soil particles and an upward flow composed mainly of contaminated water in the sedimentation separation tank. In this way, soil particles and contaminants are continuously separated, diluted water containing contaminants is continuously discharged as contaminated water from the upper part of the sedimentation tank, and the settled soil settled and separated from the descending flow is removed from the lower part of the sedimentation tank. Sedimentation and separation step of continuously discharging from

  (C) A discharging step in which the settling soil is continuously discharged and transferred from the lower part of the settling separation tank using an extruder to obtain washed soil.

(2) When the volume of soil particles contained in the volume V ₀ of contaminated soil is S, the volume of contained water is G, and the volume of pollutants is P, the volume of pollutants remaining in the washed soil is In order to reduce to P1, the soil continuous washing and discharging method according to the above (1), wherein the volume W of the dilution water is operated under the conditions satisfying the following formulas (a) and (b).
W ≧ (P / P1-1) × G (a)
(G + W) /S≧1.5 (b)

  (3) The soil continuous washing and discharging method according to the above (1) or (2), wherein the extruder increases the filling rate of the subsidence during transfer of the subsidence.

  (4) The volume per hour of the contaminated soil slurry flowing into the settling tank is V, the volume of the soil particles constituting the V is S, the volume of the contained water is G, the volume of the diluted water is W, the volume of the pollutant P, and the volume per hour of the settled soil discharged from the bottom of the settling tank is V1, the volume of the soil particles constituting the V1 is S1, and the entrained water composed of each part of the contained water and dilution water Any one of the above (1) to (3), wherein a sedimentation tank satisfying the operating conditions of the following formulas (c) and (d) is used, where T1 is the volume of the pollutant and P1 is the volume of the contaminant. The soil continuous washing | cleaning discharge method of crab.

(S1 / S) ≧ 0.8 (c)
(T1 / S1) ≦ 2 (d)

(5) The volume per hour of the contaminated soil slurry flowing into the settling tank is V, the volume of soil particles constituting the V is S, the volume of contained water is G, the volume of diluted water is W, the volume of contaminants Is set to P, the operating conditions of the sedimentation tank satisfy the following (e), and
((W + G) / S) ≧ 1.5 (e)

  V1 is the volume per hour of the settled soil discharged from the bottom of the settling tank, S1 is the volume of the soil particles constituting the V1, T1 is the volume of the entrained water consisting of each part of the contained water and dilution water, and contamination. The volume of the substance is P1, and

  The volume per hour of the washed soil discharged from the outlet of the extruder connected to the settling tank is V3, the volume of the soil particles constituting the V3 is S3, and the volume of the entrained water composed of each part of the contained water and the dilution water. Is T3, the volume of contaminant is P3, and

  The volume of settled soil existing at the bottom of the settling tank is K1, the volume of soil particles constituting the K1 is SK1, the volume of entrained water consisting of each part of the contained water and dilution water is TK1, and the volume of contaminants Is PK1, and

  The volume of the washed soil at the outlet of the extruder connected to the settling tank is K3, the volume of the soil particles constituting the K3 is SK3, the volume of the entrained water consisting of each part of the contained water and the diluted water is TK3, and the contamination When the volume of the substance is PK3,

  The soil continuous washing and discharging method according to any one of the above (1) to (4), wherein an extruder that satisfies the operating conditions of the following formulas (f) to (j) is used.

(S3 / S) ≧ 0.8 (f)
(T3 / S3) ≦ 2 (g)
α = TK1 / SK1 (……) (h)
β = TK3 / SK3 (i)
(Α / β) ≧ 1.2 ……… (j)

  (6) Raise the outlet of the extruder upward, set the vertical distance between the inlet and outlet of the extruder to H1, and between the inlet of the extruder and the polluted water discharge port of the settling tank The soil continuous washing and discharging method according to any one of (1) to (5) above, wherein (H1 / H2) is 1.3 to 0.4 when the vertical distance is H2.

  (7) In any one of the above (1) to (6), in the sedimentation tank, the sedimentation height and / or pressure of the sedimentation soil is detected to control the sedimentation time of the sedimentation soil. The soil continuous washing | cleaning discharge | emission method as described in.

  (8) In the water ejector, a part of the water after purifying the polluted water continuously discharged from the upper part of the settling tank is used as the pressure water of the driving source. 7) The soil continuous washing and discharging method according to any one of 7).

  Hereinafter, the present invention will be described in detail.

The invention relating to the above (1) will be described.
In order to impart fluidity to oil, inorganic compounds, organic compounds, heavy metals and their compounds, etc., and contaminated soil contaminated by them, the invention according to (1) is used to create a mixed fluid by injecting water, and as a drive source A slurrying step (a) in which a mixed fluid is sucked with a water ejector (an example is shown in FIG. 1) using pressure water to create a contaminated soil slurry, and a contaminated soil slurry in which the injected water and the pressure water are diluted water. Is separated into a rising flow of dilution water containing a large amount of contaminants and a downward flow consisting of most soil particles, and the upward flow is recovered as contaminated water, and the soil separated from the downward flow by sedimentation is separated. It is characterized by comprising a settling and separation step (B) for continuously obtaining settling soil composed of particles, and a discharge step (C) having an extruder for continuously discharging and transferring the settling soil to be washed soil. .

(B) Slurry process The contaminated soil to be cleaned is composed of soil particles, water contained therein, and pollutants. The soil particle size is generally distributed from approximately 20000 microns to a particle size of 1 micron or less. In many cases, the volume of soil particles in the contaminated soil is substantially the same as the volume of water contained.

  Water is poured into this contaminated soil to the extent that fluidity in the pipe is ensured, and the mixture is then sucked with a water ejector as shown in FIG. The mixture is ejected from the nozzle together with 1 to 5 MPa of pressure water (preferably about 10 to 50 atmospheres of pressure water) and the sucked air, and flows into the water ejector whose pressure is reduced by the effect of the ejection.

  The mixture, the pressure water and the air are mixed while passing through the throat part, and flow out from the outlet part of the water ejector as a high-speed contaminated soil slurry. That is, a high-speed contaminated soil slurry in which dilution water composed of injected water and pressure water, contained water, and sucked air are mixed is obtained. Since this high-speed contaminated soil slurry is ejected at a speed of about 1 to 10 m / sec from the outlet of the water ejector, it passes through a speed reducer as shown in FIG. It is preferable to decelerate to about 5 m / sec to obtain a contaminated soil slurry. However, these speeds are examples, and are not limited to these.

  In addition to the injection water and pressure water, it is also possible to add water to make a soil washing slurry as dilution water. Since the contaminants are mostly present between the soil particles, the soil particles are separated from each other in the contaminated soil slurry, and the contaminants are separated from the soil particles and uniformly dispersed in the diluted water and the contained water. Compared with the concentration of the pollutant with respect to the contained water, the concentration of the pollutant with respect to the contained water and the diluted water becomes diluted in inverse proportion to the amount of the diluted water.

Even if the pollutant is a heavy metal other than a liquid such as oil, the source of heavy metal contamination is often a compound, and since the compound is attached to many soil particles, the soil particles are in a colloidal state. As a result, the heavy metal is also uniformly dispersed in the contained water and the diluted water.
Such a state is a slurrying process.

(B) Sedimentation separation process When contaminated soil slurry is injected into the vertical section of the sedimentation tank and approximately the center in the left-right direction, it is divided into a downward flow mainly composed of soil particles and an upward flow composed of dilution water. For example, the cumulative amount of soil particles from the large diameter is 95% (volume%) so that 80% (volume%) or more, preferably 95% (volume%) or more of the soil particles constituting the contaminated soil slurry is gravity settled. In the sedimentation tank with a cross-sectional area that realizes the ascent rate of the upward flow mainly composed of dilution water, the majority of the soil particles separated from the contaminated soil slurry are settled and separated using the Stokes sedimentation rate of the soil particle size It becomes a subsoil that forms a sedimentary layer at the bottom of the tank. This settling soil is continuously discharged from the settling tank.

  Although entrained water is present in the subsidence soil, the entrained water is formed from each part of the contained water and the diluted water, so the concentration of contaminants in the entrained water is inversely proportional to the amount of diluted water. Thus, the volume of contaminant per unit volume of subsidence is reduced compared to the volume of contaminant per unit volume in the contaminated soil.

On the other hand, the dilution water containing most of the contaminants separated from the contaminated soil slurry becomes an upward flow and is discharged out of the tank as contaminated water from the upper part of the settling tank. The above operation is the sedimentation separation process.
Since the contaminated water discharged from the sedimentation tank contains many contaminants, after removing the contaminants from the contaminated water, diluted water such as injection water and pressure water used in the soil continuous washing and discharging method of the present invention. Of course, it is desirable to reuse as

  As the shape of the sedimentation separation tank, a vertical cylindrical tank, an upper cylindrical lower conical tank, a rectangular tank, or the like can be used, and the sedimentation outlet is preferably at the bottom of the tank, and the drainage of contaminated water is performed. There may be a plurality of outlets located in the upper part of the tank.

(C) Discharge process The settled soil is discharged out of the tank and transferred through an extruder connected to the sedimentation tank.
The extruder prevents the contaminated soil slurry injected into the settling tank from settling and forming a sediment layer, that is, preventing it from flowing out of the settling tank with more entrained water than the target, and at the same time In order to reduce water, the sedimentation soil is transported while also having the function of controlling the discharge amount of the extruder so as to maintain the necessary accumulation time in the sedimentation tank. The necessary deposition time is about 0.5 to 3 minutes.

The invention relating to the above (2) will be described.
When the volume of soil particles contained in the volume V _{0 of the} contaminated soil is S, the volume of the contained water is G, and the volume of the pollutant is P, the concentration ratio R ₀ of the pollutant to water is (P / G). .

When a homogeneous slurry is formed with the volume W of the dilution water and the contaminated soil V ₀ , the concentration ratio RS of the pollutant to water is (P / (G + W)). Naturally, the pollutant concentration ratio RS is small compared to _R0 . As an ideal condition, assuming that the total amount of soil particles is separated from the slurry and the volume of the entrained water is G corresponding to the amount of contained water, the pollutant P1 in the entrained water is (P / (G + W)) XG. Therefore, the dilution water W necessary for reducing the contaminants remaining in the cleaning soil to the volume P1 may satisfy the following formula (a).

W ≧ ((P / P1) −1) × G (a)
The following formulas (a-1), (a-2), (a-3) and (a-4) are introduction formulas of the above formula (a).

P1 = (P / (G + W)) × G (a-1)
P1 / P = G / (G + W) ......... (a-2)
(G + W) = G × (P / P1) (a-3)
W = G × ((P / P1) −1) (a-4)

At the same time, the necessary amount of dilution water for ensuring the fluidity of the contaminated soil slurry in the pipe may satisfy the following formula (b).
(G + W) /S≧1.5 (b)

The invention according to (2) is the soil continuous washing and discharging method according to the above (1), characterized in that the operation is performed under conditions satisfying these expressions (a) and (b).
Moreover, when reducing this pollutant P to P1, it is desirable to implement | achieve by multistage operation of 2 times or 3 times etc. according to the degree of the reduction.

The invention relating to (2) will be described in more detail.
In the present invention, the contaminated soil slurry produced in the slurrying process is transferred to the next sedimentation separation process, where it is continuously settled and separated in the sedimentation separation tank, so that most of the soil particles are descended and separated from the soil particles. The diluted water containing pollutants becomes an upward flow, is separated as contaminated water, and is discharged out of the tank.

The concept of this phenomenon is as follows.
The mass balance of the soil slurry fluid in the settling tank is shown in FIG. In FIG. 3, the flow rate (V) of slurry continuously flowing into the settling separation tank, the flow rate (V2) of contaminated water continuously discharged from the upper part of the settling separation tank, and continuous discharge from the lower part of the settling separation tank. The flow rate (V1) of the settled soil is as follows.

V = S + G + W + P
V2 = S2 + W2 + P2
V1 = S1 + G + W1 + P1
V = V1 + V2
In addition, the symbol regarding a soil slurry fluid is as follows (a unit is a volume per time).

V: Flow rate of slurry continuously flowing into the settling tank (ie, V1 + V2)
V1: Flow rate of sedimentary soil discharged continuously from the lower part of the sedimentation tank V2: Flow rate of contaminated water continuously discharged from the upper part of the sedimentation tank S: Total volume of soil particles in the contaminated soil (ie, S1 + S2) )
S1: Volume of soil particles continuously discharged from the lower part of the sedimentation tank S2: Volume of soil particles continuously discharged from the upper part of the sedimentation tank

P: Volume of pollutant in the contaminated soil (ie P1 + P2)
P1: Volume of contaminants continuously discharged from the lower part of the sedimentation tank P2: Volume of contaminants continuously discharged from the upper part of the sedimentation tank W: Volume of diluted water added to the contaminated soil (ie, W1 + W2)
W1: Volume of dilution water continuously discharged from the lower part of the settling separation tank W2: Volume of dilution water discharged continuously from the upper part of the settling separation tank

G: Volume of water contained in the contaminated soil before washing T: Water amount per unit soil in the slurry at the inlet of the sedimentation tank (ie, contained water G + diluted water W)
Further, symbols related to other than the slurry fluid are as follows.
u1: Average speed when the fluid V1 flows down the sedimentation tank (ie, V1 / A)
u2: Average speed when fluid V2 moves up the sedimentation tank (ie, V2 / A)
This u2 is equal to the sedimentation speed of the soil particle diameter at which the amount of accumulated fine particles of the soil becomes S2.

A: Cross-sectional area of sedimentation separation tank (the cross-sectional area that realizes u2)
D: Diameter or equivalent diameter of the cross section of the sedimentation separation tank (Note that the equivalent diameter means a diameter assuming a circular area equal to the cross sectional area when the cross sectional shape is not circular.)
L1: Longitudinal section length of sedimentation separation tank where fluid V1 flows down L2: Longitudinal section length of sedimentation separation tank where fluid V2 rises R: Sedimentation speed of soil particles

The conditions for transferring the slurry are preferably (G + W) /S≧1.5 in order to secure the fluidity of the slurry and transfer the piping.
In order to realize the pollutant P1 of the washing soil from the pollutant content P per volume V _{0 of the} contaminated soil, the condition of the dilution water W satisfies W ≧ (P / P1-1) × G So, soil cleaning can be realized.

The invention relating to the above (3) will be described.
When the extruder discharges the settled soil from the lower part of the sedimentation tank and transfers it to the washed soil, the amount of entrained water in the settled soil is small, that is, the packing density of the soil particles is large, which improves the washing rate. Become. Therefore, it is preferable to reduce the entrained water when a situation occurs in which the entrained water of the subsoil increases due to fluctuations in operating conditions such as at the start of operation. As the method, when the cross-sectional diameter D1 of the screw at the inlet of the extruder and the cross-sectional diameter D3 of the outlet are set, the screw diameter is gradually decreased toward the outlet so as to satisfy (D1 / D3) ≧ 1.5. In addition, it is preferable to increase the packing density inside the screw by reducing the screw length L to L ≧ (4 × D1) and to reduce the entrained water.

As another method, the packing density can be increased by installing a cylinder that constantly compresses the soil at a pressure of 20 KPa (0.2 atm) or more at the outlet of the extruder.
Thus, it is preferable in the present invention to have an extruder having a function for reducing entrained water.

The invention relating to the above (4) will be described.
The volume per unit time of the contaminated soil slurry flowing into the settling tank is V, the volume of soil particles constituting the V is G, the volume of water contained is G, the volume of diluted water is W, and the volume of contaminants And P1, the volume per unit time of the subsidence discharged from the bottom of the subsidence separation tank is V1, the volume of the soil particles constituting the V1 is S1, and the entrained water consists of a part of the contained water and dilution water. When the water volume is T1 and the pollutant volume is P1, the cumulative amount of soil fine particles floating in the upward flow of the sedimentation tank (contaminated water mainly containing the pollutant separated from the contaminated soil slurry) is It is preferable that the accumulated amount achieves the target yield of the soil particles.

  That is, in order to reduce the rising soil particles as much as possible, it is preferable to set the cross-sectional area of the sedimentation separation tank so as to realize the Stokes velocity in which the particle diameter that becomes the boundary of the cumulative amount is the floating limit. Specifically, it is preferable to use a sedimentation tank capable of achieving a washing soil yield of 80% (volume%) or more and realizing entrained water twice or less the volume of soil particles.

Such operating conditions are conditions that satisfy the following formulas (c) and (d).
(S1 / S) ≧ 0.8 (c)
(W1 / S1) ≦ 2 (d)

The invention relating to the above (5) will be described.
The volume per unit time of the contaminated soil slurry flowing into the settling tank is V, the volume of soil particles constituting the V is S, the volume of contained water is G, the volume of diluted water is W, and the volume of contaminants is When P is set, it is preferable that the operating conditions of the sedimentation tank satisfy ((W + G) / S) ≧ 1.5. In addition, in the settled soil discharged from the bottom of the settling tank, accompanying water composed of part of the contained water G and dilution water W is present, and it is desirable that the amount of accompanying water is small in order to increase the washing rate. As a means for reducing the amount of entrained water as much as possible, it is preferable to reduce the amount of entrained water by adding a compression function by reducing the screw diameter toward the longitudinal direction of the screw shaft at the same time as being transferred by an extruder.

This function is described as follows.
The volume per unit time of the subsidence discharged from the bottom of the subsidence separation tank is V1, the volume of soil particles constituting the V1 is S1, the volume of entrained water consisting of each part of the contained water and the dilution water is T1, And the volume of the pollutant is P1, and the volume per unit time of the washing soil discharged from the outlet of the extruder connected to the settling tank is V3, the volume of the soil particles constituting the V3 is S3, The volume of entrained water composed of each part of the dilution water is T3, the volume of the pollutant is P3, the unit volume of the subsidence soil discharged from the bottom of the subsidence separator is K1, and the soil particles constituting the K1 The volume of SK1, the volume of entrained water composed of contained water and dilution water is TK1, the volume of contaminants is PK1, and the unit volume of the washing soil discharged from the outlet of the extruder connected to the settling tank is K3, The volume of the soil particles constituting the K3 When the volume of entrained water consisting of K3, containing water and dilution water is TK3, and the volume of contaminants is PK3, the yield of the washing soil at the exit of the extruder is desirably large, and (S3 / S) is 0. It is preferably 8 or more, and more preferably 0.95 or more economically.

  Furthermore, it is desirable that the amount of water accompanying the washing soil is as small as possible because it leads to an improvement in the washing rate, and (T3 / S3) is preferably 2 or less, and more preferably 1.5 or less.

  In order to realize this condition, when the case of (T1 / S1) ≧ 2 occurs in the sedimentation soil of the sedimentation tank, a function to increase the filling rate of the soil particles with an extruder is required. That is, when expressed as (volume of water) / (volume of soil particles) as an index of the filling rate of soil particles, α = TK1 / SK1, if the filling rate indexes at the inlet and outlet of the extruder are α and β, β = TK3 / SK3. This filling rate index is increased by an extruder, and the degree thereof is preferably (α / β) ≧ 1.2.

The invention relating to the above (6) will be described with reference to FIG.
This is an embodiment in which an extruder is inclined. If the B point of the outlet part of the extruder is raised upward and the horizontal height of the outlet is above the horizontal height of point C of the contaminated water discharge port of the settling tank, the entrained water of the subsidized soil is Even when there are many at the start of operation or when conditions change, it is possible to prevent the slurry from leaking and at the same time to compress the sediment. This is important in order to operate the sedimentation separation tank continuously and stably.

  The exit B point of the extruder may not always need to be positioned higher than the horizontal height of the contaminated water discharge point C. That is, from the composition of the soil particles, when the settled soil is easy to deposit and the dewaterability is high (the soil filling density is large), the exit B point of the extruder is more than the horizontal position of the contaminated water discharge port C point. Even in a low position, the sedimentation tank can be operated continuously and stably. Furthermore, if considering that the outflow of the sediment due to the resistance of the screw of the extruder is prevented, the vertical distance between the inlet portion F point of the extruder and the outlet portion B point of the extruder is H1, When the vertical distance between the inlet F point of the extruder and the contaminated water discharge port C point of the settling tank is H2, (H1 / H2) is preferably 0.4 to 1.2, more preferably. Is 0.8 to 1.1, and ideally (H1 / H2) = 1.

The invention relating to the above (7) will be described.
Sedimented sediment separated in the sedimentation tank forms a deposited layer with a high packing density toward the bottom of the tank, but it is necessary to secure the packing density to achieve the target cleaning at the sedimentation tank outlet. is there. Therefore, the height of the deposited layer is required to realize the packing density. That is, if the required height of the deposited layer does not exist, the amount of entrained water increases and the cleaning rate deteriorates. Therefore, in order to always maintain the height of the deposited layer, it is necessary to grasp the height of the deposited layer. In order to maintain the height of the sedimentary layer within an appropriate range, the height of the sedimentary layer is measured with a propeller level meter, or the pressure due to the sedimentary layer height is detected with a diaphragm pressure gauge, It is preferable to control the deposition time. For that purpose, for example, it is preferable to control the rotation speed of the extruder.

The invention relating to the above (8) will be described.
In order to reduce the volume of contaminants remaining in the washed soil to P1, where S is the volume of soil particles contained in the unit volume V ₀ of the contaminated soil, G is the volume of water contained, and P is the volume of contaminants. When the volume W of diluted water in the contaminated soil is operated under the conditions satisfying the above formulas (a) and (b), a part of the volume W of the diluted water is used as pressure water for the drive source of the water ejector. It is preferable to do.

  The soil continuous washing and discharging method of the present invention is continuous, and at the same time, the equipment can be downsized, and at the same time, by recirculating and using the water after purifying the contaminated water, the proportional cost can be significantly reduced. .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further, this invention is not limited only to these Examples.

[Example 1]
FIG. 5 is a schematic diagram illustrating a soil continuous washing and discharging method in the first embodiment.
Contaminated soil by oil (soil particles constituting the soil 0.94 m ³ / hr, containing water ^{1 m} 3 / hr and the oil 0.06 m ³ / hr) the mixture consisting of and injection water ^(2m 3 / hr), the pressure High speed contaminated soil slurry is made through a water ejector driven by water (4 m ³ / hr, pressure 20 MPa) and air (10 m ³ / hr).

At this time, the high-speed contaminated soil slurry is a diluting water of 6 m ³ / hr which is the sum of the injected water and the pressure water, and the oil that is the pollutant is a jet dispersed uniformly in the contained water and the diluting water. Therefore, it was decelerated through a decelerator to obtain a contaminated soil slurry. The speed reducer used was as shown in FIG. 2 described above, and had an impact disk built in a cylindrical tube having a diameter of 300 mm and a length of 1 m at the inlet and outlet and a thick central portion. In addition, the inflowing slurry collides here and decelerates by exhausting air.

As shown in FIG. 5, the above-mentioned contaminated soil slurry is placed in the center in the vertical direction of a cylindrical conical sedimentation separation tank consisting of a 1 m diameter 1 m high cylinder part and a 1 m 1 m high cone part. Introduced. Most of the soil particles in the contaminated soil slurry settle down as a downflow and become sedimentary soil. The composition of該沈Hod was soil particles 0.92 m ³ / hr, water 1.3 m ³ / hr and the oil 0.01 m ³ / hr. This subsidence soil is transferred by an extruder connected to a sedimentation separation tank to be washed soil. The composition of the washed soil is the same as that of the subsidence soil.

On the other hand, most of the dilution water separated from the contaminated soil slurry in the settling tank becomes an upward flow and is discharged out of the tank as contaminated water. The composition of the contaminated water, water 5.7 m ³ / hr, was soil particles 0.02 m ³ / hr and the oil 0.05 m ³ / hr.
As a result, the oil in the washed soil was reduced to 17% (oil removal rate 83%) compared to the oil in the contaminated soil (100%). Moreover, the soil yield reached 98%.

[Example 2]
FIG. 6 is a schematic diagram illustrating a soil continuous washing and discharging method in the second embodiment.
In Example 2, it operated using what reduced the height of the cone part of the sedimentation tank in Example 1 to 0.5 m.
Since the conditions from the contaminated soil to the production of the contaminated soil slurry were the same as in Example 1, the composition of the contaminated soil slurry in Example 2 was the same as that in Example 1.

Velocity of each composition of the precipitated soil, soil particles 0.90 m ³ / hr, but was water 1.5 m ³ / hr and the oil 0.013 m ³ / hr, the volume composition per liter of sedimentation soil Soil The particles were 0.31 liter, water was 0.684 liter, and oil was 0.006 liter.

The settled soil was transferred to a washing soil by an extruder connected to the sedimentation tank.
The used extruder has a shape in which the cross section of the screw is narrowed from the inlet portion toward the outlet portion. Specifically, when the cross-sectional diameter of the screw shaft of the extruder is constant Ds, the screw cross-sectional diameter of the inlet portion of the extruder is De, the screw cross-sectional diameter of the outlet portion is Do, and the screw length is Ls, Ls = 6 Ds, and the screw cross-sectional diameter was gradually decreased from De = 3 Ds to Do = 2 Ds from the inlet to the outlet.
By increasing the packing density of such soil particles using an extruder design, velocity of each composition of the cleaning soil, soil particles 0.9 m ³ / hr, water 1.5 m ³ / hr and the oil 0. The volume composition per liter of the washed soil was 0.37 liter of soil particles, 0.625 liter of water, and 0.005 liter of oil, although it was 013 m ³ / hr.

On the other hand, most of the dilution water separated from the slurry in the settling tank becomes an upward flow and is discharged out of the tank as contaminated water. The composition of the contaminated water was soil particles 0.04 m ³ / hr, the oil 0.047m ³ / hr, and water 5.5 m ³ / hr. Further, α of the filling rate index defined in (5) was 2.2, β was 1.7, and α / β = 1.3.
As a result, the oil in the washing soil was reduced to 22% (oil removal rate 78%) compared to the oil (100%) in the contaminated soil. The soil yield reached 96%.

  The soil continuous washing and discharging method of the present invention can purify contaminated soil caused by oil, organic compounds, heavy metals and their compounds and complex pollution, etc., continuously and at low cost by using small equipment. It is extremely useful for solving environmental problems.

It is the schematic of an example of the water ejector used for this invention. It is the schematic of an example of the speed reducer used for this invention. It is a figure which shows the mass balance of the soil slurry fluid in a sedimentation tank. In the method of this invention, it is the schematic which shows the example in the case of using an extruder inclined. It is the schematic which shows the soil continuous washing | cleaning discharge method of Example 1. FIG. It is the schematic which shows the soil continuous washing | cleaning discharge method of Example 2. FIG.

Explanation of symbols

F Inlet part B Outlet part C Contaminated water outlet H1 Vertical distance between F and B H2 Vertical distance between F and C

Claims (8)

The soil continuous washing | cleaning discharge method characterized by having the following (I), (B), (C).
(I) Mixing a mixture of contaminated soil composed of soil particles, contaminants and contained water and water injected to impart fluidity to the contaminated soil with a water ejector driven by pressure water. , A slurrying process that continuously creates a contaminated soil slurry using the injected water and pressure water as dilution water,
(B) Injecting the contaminated soil slurry into the center of the sedimentation separation tank, and dividing the slurry into a downward flow mainly composed of soil particles and an upward flow composed mainly of contaminated water in the sedimentation separation tank. In this way, soil particles and contaminants are continuously separated, diluted water containing contaminants is continuously discharged as contaminated water from the upper part of the sedimentation tank, and the settled soil settled and separated from the descending flow is removed from the lower part of the sedimentation tank. Sedimentation and separation step of continuously discharging from
(C) A discharging step in which the settling soil is continuously discharged and transferred from the lower part of the settling separation tank using an extruder to obtain washed soil. When the volume of soil particles contained in the volume V ₀ per unit time of contaminated soil is S, the volume of contained water is G, and the volume of pollutants is P, the volume of pollutants remaining in the washed soil is reduced to P1. In order to make it operate | move, the volume W of dilution water operates on the conditions which satisfy | fill following formula (a) and (b), The soil continuous washing | cleaning discharge method of Claim 1 characterized by the above-mentioned.
W ≧ (P / P1-1) × G (a)
(G + W) /S≧1.5 (b)   3. The soil continuous washing and discharging method according to claim 1 or 2, wherein the extruder increases the filling rate of the settled soil during transfer of the settled soil. The volume per hour of the contaminated soil slurry flowing into the settling tank is V, the volume of the soil particles constituting the V is S, the volume of the contained water is G, the volume of the diluted water is W, and the volume of the pollutant is P. And V1 is the volume per hour of the settled soil discharged from the bottom of the settling tank, S1 is the volume of the soil particles constituting the V1, and the volume of entrained water consisting of each part of the contained water and the dilution water. The soil continuation according to any one of claims 1 to 3, wherein a sedimentation separation tank that satisfies the operating conditions of the following formulas (c) and (d) is used when T1 and the pollutant volume are P1. Cleaning discharge method.
(S1 / S) ≧ 0.8 (c)
(T1 / S1) ≦ 2 (d) The volume per hour of the contaminated soil slurry flowing into the settling tank is V, the volume of soil particles constituting the V is S, the volume of contained water is G, the volume of diluted water is W, and the volume of pollutants is P. When the operation condition of the sedimentation tank satisfies the following (e), and
((W + G) / S) ≧ 1.5 (e)
V1 is the volume per hour of the settled soil discharged from the bottom of the settling tank, S1 is the volume of the soil particles constituting the V1, T1 is the volume of the entrained water consisting of each part of the contained water and dilution water, and contamination. The volume of the substance is P1, and
The volume per hour of the washed soil discharged from the outlet of the extruder connected to the settling tank is V3, the volume of the soil particles constituting the V3 is S3, and the volume of the entrained water composed of each part of the contained water and the dilution water. Is T3, the volume of contaminant is P3, and
The volume of settled soil existing at the bottom of the settling tank is K1, the volume of soil particles constituting the K1 is SK1, the volume of entrained water consisting of each part of the contained water and dilution water is TK1, and the volume of contaminants Is PK1, and
The volume of the washed soil at the outlet of the extruder connected to the settling tank is K3, the volume of the soil particles constituting the K3 is SK3, the volume of the entrained water consisting of each part of the contained water and the diluted water is TK3, and the contamination When the volume of the substance is PK3,
The continuous soil washing and discharging method according to any one of claims 1 to 4, wherein an extruder that satisfies the operating conditions of the following formulas (f) to (j) is used.
(S3 / S) ≧ 0.8 (f)
(T3 / S3) ≦ 2 (g)
α = TK1 / SK1 (……) (h)
β = TK3 / SK3 (i)
(Α / β) ≧ 1.2 ……… (j)   Raise the outlet of the extruder upward, let H1 be the vertical distance between the inlet and outlet of the extruder, and let the vertical distance between the inlet of the extruder and the contaminated water discharge port of the settling tank The soil continuous washing and discharging method according to any one of claims 1 to 5, wherein when H2, (H1 / H2) is 1.3 to 0.4.   The soil continuous washing according to any one of claims 1 to 6, wherein the sedimentation height of the sedimentation soil and / or the pressure of the sedimentation soil is detected in the sedimentation tank to control the sedimentation time of the sedimentation soil. Discharge method.   In a water ejector, a part of water after purifying the polluted water continuously discharged | emitted from the upper part of a sedimentation-separation tank is used as pressure water of a drive source. The soil continuous washing discharge method as described.

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