JP2001121136A - Soil washing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the polluted environment sound and to enable the effective utilization of removed hazardous materials by removing almost all of the hazardous materials, such as dioxin and heavy metals, included in soil. SOLUTION: The soil 1 is fed into the air-containing high-pressure jet water flow in a washing running-down pipe 2 and a flocculating agent is supplied thereto. The soil fed into the washing running-down pipe 2 is intensively jostled by the air-containing high-pressure jet water flow 6 and is decomposed to soil particles 7 and solid lumps 8 like stones. Further, the deposits 9 of the solid lumps 8 are also completely peeled. The soil particles 7 and peeled materials 11 containing there hazardous materials are captured by the flocculating agent 10 and flocculated sludge 12 is formed. The flocculated sludge is mingled with mud water together with the solid lumps 8 and is discharged. Accordingly, the hazardous materials in the soil may be completely captured as the flocculated sludge 12. Further, the flocculated sludge is granulated by a solidifying agent and is formed to round grains, etc., from which the hazardous materials are not eluted. The found grains etc., may be recycled to regenerated building materials, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil washing apparatus, and more particularly to a soil washing apparatus, which is suitable for separating and removing harmful substances including dioxin and the like contained in soil to obtain healthy soil. A simple soil washing device.

[0002]

2. Description of the Related Art In recent years, various harmful substances contained in soil have become a problem. The following are generally listed as harmful substances contained in soil. Mercury or its compound, cadmium or its compound, lead or its compound, hexavalent chromium or its compound, arsenic or its compound, organic phosphorus compound, cyanide, PC
B, dioxin, trichloroethylene, atrachloroethylene, selenium or a compound thereof.

[0003] As a method of treating these harmful substances in the soil, there are studies to mix specific chemicals into the soil containing the harmful substances to detoxify the specific harmful substances, and to add soil such as cement to the soil. There is a method of mixing with a solidifying agent and solidifying with concrete (for example, see Japanese Patent Publication No. 52-47483).

[0004] Soil improvement methods for improving the acidity and alkalinity of soil are generally carried out, but they have not been able to remove harmful substances such as heavy metals and PCBs contained in soil.

[0005]

The above-mentioned conventional soil improvement method for neutralizing or alkalizing acidic soil cannot detoxify harmful substances including dioxin and the like in soil.

Further, the method of mixing and solidifying a soil containing a harmful substance with a solidifying agent has a problem that the soil is hardened. In addition, the harmful substances may be dissolved from the hardened soil, and the harmful substances cannot be completely removed.

[0007] In general soil, in addition to soil, sand, gravel, rocks, etc., various things are usually mixed. For example, metal pieces, glass pieces, cloth pieces, resins, animals and plants are mixed. Here, not only soil, but also a concept including these inclusions is referred to as soil.

The harmful substances are present in the soil,
They also adhere to these inclusions. Therefore, it was not possible to treat all harmful substances under all conditions simply by mixing the chemical with the soil.

An object of the present invention is to remove harmful substances such as dioxins and heavy metals contained in soil, to purify the soil and to make the polluted environment sound, and to enable the effective use of the removed harmful substances. It is.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have studied a means for removing harmful substances such as dioxins and heavy metals from soil and preventing these harmful substances from being eluted into groundwater. And conducted various studies.

As a result, the soil is thoroughly washed together with various contaminants and solid lumps contained therein, and residues containing harmful substances washed out of the soil and solid lumps are collected as sludge and dissolved in groundwater or the like. A means for granulating into a granular material without the inventor was devised.

That is, the soil washing apparatus of the present invention comprises a pipe for feeding soil together with washing water, an aerated high-pressure jet water stream generating means for generating a high-pressure jet water stream containing air in the pipe, And a coagulant supplying means for supplying a coagulant to the pipe.

When the soil is put into the high-pressure jet water stream containing the air, and the coagulant is supplied and fed through the straight pipe, the sediment and solid lumps are washed cleanly, and the harmful substances washed out are coagulated as sludge. Is discharged. In particular, it is effective to use an inorganic coagulant as a powder. In addition, mobility can be improved by using this apparatus as a vehicle-mounted type.

According to the present invention, by applying a flocculant to the high washing action of the aerated high-pressure jet water stream, not only harmful substances contained in the soil but also solid matters such as stones and metal fragments can be obtained with a simple structure. Even harmful substances adhering to the lump are completely removed and agglomerated as sludge.

Further, the waste water from which the flocculated sludge has been separated is re-washed or reused as driving water for the jet water flow, whereby the waste water can be efficiently purified. Further, the separated coagulated sludge is granulated so that harmful substances are not eluted, and can be effectively used.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of a soil cleaning device of the present invention.

As shown in FIG. 1, the present apparatus comprises a washing pipe 2 made of a steel pipe for flowing soil 1 together with an air-mixed high-pressure jet water stream mixed with air, and an air mixture into the washing pipe 2. Plunger pump 3 for generating high-pressure jet water flow
And a coagulant quantitative supply device 4 for supplying the coagulant into the high-pressure jet water flow, and includes a hopper 5 for charging the soil 1 into the high-pressure jet water flow.

FIG. 2 is a cross-sectional view showing a state of soil conveyed in the washing flow pipe 2. The soil introduced into the washing flow pipe 2 is violently swirled by the mixed high-pressure jet water stream 6, is decomposed into solid particles 8 such as soil particles 7 and stones, and is washed and fed. At this time, the deposits 9 attached to the solid mass 8 and the soil particles 7 are almost completely peeled off to form the peeled material 11.

The coagulant 1 is contained in the mixed high-pressure jet water stream 6.
If 0 is supplied, soil particles 7 containing harmful substances and exfoliated materials 11
Is also agglomerated into an agglomerate 12 called sludge, which is discharged together with the solid mass 8 in the muddy water.

The mechanism of cleaning inside the cleaning flow pipe 2 is as follows. The soil particles 7 and solid lumps 8 which are to be cleaned are violently swirled by the air-mixed high-pressure jet water stream 6 and are strongly cleaned. The solid masses 8 violently collide with each other, and the deposits 9 containing harmful substances and the like are separated.

Since the inner wall of the steel pipe of the cleaning pipe 2 and the soil come into intense contact with each other, the deposits 9 of the solid mass 8 are peeled off, and the solid soil is also decomposed into soil particles 7. The soil particles 7 containing the harmful substances, the exfoliated materials 11, and the like are collected by the coagulant to form coagulated sludge 12. The above is a function peculiar to a high-pressure aerated jet pump.

In this way, the soil introduced into the jet water flow in the pipe is decomposed into soil particles and solid lumps, and the soil particles containing harmful substances and exfoliated matters are collected by the coagulant to form coagulated sludge 12. Thus, the jet water flow becomes a jet of the mixed muddy water, and the solid lump 8 is fed through the pipe while continuing to roll.

Next, a soil improvement plant which is an example of a soil improvement system to which the soil cleaning device of the present invention is applied will be described with reference to FIGS. FIG. 3 is a configuration diagram of a soil improvement plant, and FIG. 4 is a soil improvement processing flow. This plant is configured as follows, and the improvement processing is performed.

The backhoe 21 excavates and collects the soil 20 to be improved (S1). In the excavated soil 20,
As described above, in addition to earth and sand, solid lumps such as rocks, waste, and various kinds of waste are mixed. Therefore, these are pulverized to a predetermined diameter or less by the pulverizer 22 as a plan A (S2). In this example, the size may be 90% or less of the pipe diameter of the cleaning flow pipe 2.

The soil containing the solid lumps having a predetermined diameter or less is supplied to a hopper 24, which is a means for charging the soil into the soil washing / flowing pipe 25 (S4). In this case, B
As a plan, by using a hopper 23 with a screen such as a vibrating screen, without using the crusher 22,
It is also possible to screen out a solid lump having a predetermined diameter or less (S
3).

A mixed high-pressure jet water flow is generated in the washing flow pipe 25 by a plunger pump 26 (S).
5) With the high-pressure jet water stream mixed with the air, the soil and the like put into the pipe are sent while being strongly washed (S7). As an example, an inner diameter of 1
When using a steel pipe of 50 mmφ and an extension of about 5 m, about 100
Cubic m / H soil can be treated.

In this example, almost simultaneously with the supply of the soil 20,
A predetermined amount of coagulant is supplied into the washing flow pipe 25 (S6).
A coagulant metering and feeding device 27 is provided. By generating a jet water flow in the cleaning flow pipe 25 and supplying an object to be cleaned such as soil and an aggregating material thereto, as described in FIG. It is discharged as coagulated sludge.

The discharge discharged from the cleaning flow pipe 25 is as follows.
Mesh: Separated into solids 29 having a predetermined diameter or more to which no harmful substances are adhered and sludge water 30 composed of aggregates containing harmful substances and sewage while being washed with a screen 28 having a shower of 0.5 cm to several cm. Is performed (S8).

The solids 29 (S9) to which no harmful substances have been selected by the screen 28 with a shower are conveyed to a predetermined yard by a conveyor such as a belt conveyor 31 (S10), and the final cleaning process is performed. Soil and sand 32 (S1
1) and reused.

The sludge water 30 containing harmful substances (S12) selected by the screen 28 with a shower is collected in a receiving tank 35 (S13), and then the sediment such as agglomerates is settled in a settling tank 36. Separate the supernatant (S1
6).

In this case, before sending the sludge water collected in the receiving tank 35 to the sedimentation tank 36, if necessary,
The coagulant is supplied from the coagulant quantitative supply device 38 in the stirring tank 37 (S14), and is stirred by the stirrer 39.
Aggregates harmful substances and the like in the sludge water (S15).

In the present invention, the soil to be washed and the discharge from the washing flow pipe 25 are inspected in advance,
If the harmful substances are effectively removed as aggregates, the reaggregation step using the stirring tank 37 can be omitted.

The sludge such as agglomerates containing harmful substances precipitated in the sedimentation tank 36 is removed by a sludge pump 40 to a dehydrator 41.
It is sent to (S17) and dewatered, and becomes the coagulated sludge 42 or the dewatered cake (S18). The coagulation sludge 42 or the dewatered cake is mixed with the solidifying agent 43 (S1).
9) Granulate with the granulation mixer 44 (S20) (S2
1) In this example, round grains 45 having an average of several mm
I made it.

In the experiments of the present inventors, when granulation was performed using a cement-based solidifying agent, harmful substances were contained in the round particles, and did not elute into, for example, groundwater. .

Since the granules 45 thus granulated do not elute harmful substances, they can be transported to a recycling plant 46, and can be effectively used for construction materials such as road base materials, bricks, blocks and the like.

The supernatant separated in the sedimentation tank 36 is collected in the water tank 47 together with the water dewatered from the mud by the dehydrator 41 (S22), and the plunger pump 26 is re-used as a mixed high-pressure jet water stream. The cleaning fluid is again supplied to the cleaning flow pipe 25 via the cleaning pipe 25. In the process, water is appropriately supplied from a water truck 48 or the like to maintain a required water amount.

In the above description, the harmful substances in the soil are agglomerated by the aggregating agent while the soil is put into the washing flow pipe and washed with the mixed air jet stream, but the present invention is not limited to this. That is, it is possible to wash and purify the sludge water after the soil washing with the washing flow pipe.

That is, the mixed air and the high-pressure jet water flow are generated by the sewage in the water tank 47 such as the supernatant of the sedimentation tank 36 and the contaminated water from the dehydrator 41 without charging the soil into the washing flow pipe 25. The harmful substances in the sewage can be captured by the coagulant and removed as the coagulated sludge 42. Further, by repeating this cycle and circulating the sewage, it is possible to purify the water to a quality that can be naturally discharged.

Here, the flocculant in the present invention will be described. As the flocculant in the present invention, an inorganic flocculant is preferable. For example, bentonite, zeolite, fly ash, slaked lime, natural minerals such as anhydrous gypsum, aluminum salts, iron salts, etc., alone or in appropriate combination, may be supplied directly to the washing flow pipe in powder or solid form and line blended. .

When the soil is introduced into the jet stream, the soil is decomposed into soil particles and solid lumps, and the deposits attached to the solid lumps are also separated, and these become suspended substances in the water stream. Therefore, harmful substances in the soil will be included in this suspended substance. This suspended substance is agglomerated by the aggregating agent to form agglomerated sludge.

The amount of the inorganic coagulant to be added in the present invention may slightly increase or decrease, but the purpose can be achieved within the range of 50 to 300 mg / l. By adding an appropriate amount of an inorganic coagulant as it is to the jet water flow in the washing flow pipe as it is and stirring vigorously with the jet water flow, the reaction is completed in 1 to 2 minutes.

From the washing flow pipe, solid lump having the attached matter washed thereon or coagulated sludge containing harmful substances is mixed with the washing water and discharged. The discharged flocculated sludge immediately begins to settle, completely separates from the supernatant water, and its interface is also clear.

The coagulated sludge by the inorganic coagulant is mainly composed of an oxide, has extremely high stability and dehydration properties, and does not collapse or dissolve even when stirred again. Rather,
The aggregation density tends to increase, which confirms that the stability is high over time. On the other hand, sludge generally formed of an organic polymer flocculant is mainly composed of hydroxide, and thus lacks dehydration properties.

Table 1 shows a comparison table between commonly used organic polymer flocculants and inorganic flocculants in the present invention. As described in Table 1, both have the following differences in operation and effect due to the difference of the main components.

[0045]

[Table 1]

(1) In the reaction to a suspended substance, the suspended substance is linked by crosslinking in an organic system, whereas
In an inorganic system, it is due to an adsorption action. (2) Therefore, the floc strength is low in an organic system. That is, the mechanical strength is weak, and it is easy to collapse. In an inorganic system, the flock strength is extremely strong.

(3) Due to the strength of the bonding force, turbidity remains in the supernatant in the case of an organic system, but the transparency of the supernatant is higher in an inorganic system than in an organic system. (4) The coagulated sludge by the organic coagulant has a water content, and therefore has a sticky feeling and poor dewatering property. Sludge by the inorganic coagulant becomes small when dewatered.

(5) It is usual that the organic coagulant is dissolved in water in advance, and the aqueous solution is added to the liquid to be treated.
On the other hand, the inorganic coagulant in this example can be directly charged as it is in a powder or solid state and can be rapidly stirred, so that the workability is good.

(6) In an organic system, dissolution of a flocculant → stirring → mixing → retention → precipitation → dehydration → drying
It takes a lot of work. On the other hand, in the case of inorganic system, labor saving and cost reduction are possible because of short process such as stirring → precipitation separation → dehydration. (7) Due to the strength of the cohesive sludge, suspended solids are easily eluted in an organic system and hardly eluted in an inorganic system.

From the above, the organic polymer flocculant generally used causes viscosity in the flocculation sludge, and the sludge water becomes muddy. And maintenance is reduced.

On the other hand, the inorganic coagulant of the present invention is mainly composed of a natural mineral, and a suspended substance, that is, a suspended substance (heavy metal, organic compound, polluted substance, etc.) diffused in water is stirred for 1 minute. It has the function of coagulating and sedimenting in ~ 2 minutes.

Further, when a plurality of stages of stirring are performed, it is very effective to increase the floc. In addition, adsorption of organic substances and ammonia dissolved in water is performed at the same time.
It also demonstrates great power in reducing oD.

Further, pH adjustment is basically unnecessary, water solubility is high, and floc is formed immediately after stirring. for that reason,
The capital investment can be reduced, and the processing steps can be shortened. The pH of the treated water is about 0.2 to 0.4, which is closer to neutrality, than the raw water.

As described above, the good reactivity, the size of the agglomerated particles, the good dehydration, etc. are particularly high for the air-mix jet pump of the present invention. Very suitable for adsorbing and removing harmful substances.

Therefore, the inorganic coagulant of the present invention has a structure that does not impose a burden on the human body and the environment, unlike an organic polymer coagulant such as a polymer coagulant.
Extremely effective disposal can be achieved in waste disposal.

When the above-mentioned inorganic coagulant is used in the mixed jet water stream, the powder (coagulation) is converted into a three-phase flow of solids (soil particles, solid lumps, etc.), liquid (wash water), and gas (air). Agent)
By performing line blending, rapid floc formation is performed, and solid-liquid separation is easily performed.

As described above, the inorganic powder coagulant is preferable because the coagulation effect of the suspended substance is improved, and the viscosity of the treated water is extremely low and it is not sticky. This is because there is no maintenance, the maintenance is improved, and the water is suitable for reflux.

As described above, when the soil is put into the jet water stream in the washing flow pipe and the coagulant is supplied, the solid is easily separated into solid lumps, coagulated sludge, and treated water, and harmful substances in the soil are coagulated. Contained in the sludge, the treated water is purified water that can be discharged naturally without harmful substances. Further, the coagulated sludge can be granulated into a granular material from which no harmful substances are eluted by adding a solidifying agent and dehydrating and solidifying.

Although various embodiments have been described in connection with the present invention, the mobility of these devices and systems is greatly improved by installing these devices and systems on-site, and contaminated soil can be efficiently cleaned on-site. Therefore, it is possible to easily purify the polluted environment.

[0060]

As described above, according to the soil washing apparatus of the present invention, harmful substances such as dioxins and heavy metals in soil can be efficiently and efficiently removed by washing with mixed high-pressure jet water and the action of a coagulant. It can be removed with high precision and can be improved to a healthy soil that does not contain harmful substances.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a soil cleaning device of the present invention.

FIG. 2 is a cross-sectional view showing a state of soil conveyed in a washing flow pipe according to the present invention.

FIG. 3 is a configuration diagram of a soil improvement plant to which the present invention is applied.

FIG. 4 is a diagram showing a flow of a soil improvement treatment according to the present invention.

[Explanation of symbols]

 1,20 Soil 2,25 Cleaning flow pipe 3,26 Plunger pump 4,27 Coagulant quantitative feeder 5,24 Hopper 6 Aerated high-pressure jet water flow 7 Soil particles 8 Solid lump 9 Deposit 10 Coagulant 11 Contamination Soil 12 Agglomerate 32 Washed earth and sand 36 Sedimentation tank 41 Dehydrator 42 Coagulated sludge 43 Solidifying agent 44 Granulator 45 Round granules 47 Water tank

Continued on the front page F term (reference) 2E191 BA02 BA11 BA12 BA13 BA15 BB01 4D004 AA41 AB03 AB06 AB07 BA02 CA12 CA13 CA14 CA40 CA50 CB44 CB45 CC03 CC13 CC20 4D015 BA04 BB08 BB16 CA10 DA02 DA24 DA25 DA32 DA35 DA36 EA06 EA32 FA30

Claims (8)

[Claims] 1. A cleaning flow pipe for flowing soil together with cleaning water, a mixed high pressure jet water flow generating means for generating a high pressure jet water flow mixed with air in the cleaning flow pipe, and a coagulation in the jet water flow. And a coagulant supply means for supplying an agent. 2. The soil washer according to claim 1, wherein the coagulant is a powder mainly composed of a natural mineral. 3. A soil washing vehicle equipped with the soil washing device according to claim 1. 4. A soil washer comprising a sludge separating means provided at a subsequent stage of the soil washer according to claim 1 or 2, for separating coagulated sludge in effluent discharged from a washing pipe of the soil washer. system. 5. The soil cleaning system according to claim 4, further comprising a drainage resupply pipe for resupplying the wastewater from which the flocculated sludge has been separated to the cleaning flow pipe. 6. The soil cleaning system according to claim 4, further comprising a driving water supply pipe for supplying the wastewater from which the flocculated sludge is separated as driving water for the jet water flow of the cleaning flow pipe. 7. The soil washing system according to claim 4, further comprising a granulating means for granulating the agglomerated sludge after the sludge separating means. 8. A harmful substance in the soil by generating a high-pressure jet water stream mixed with air, charging the soil into the jet water stream, supplying an inorganic coagulant, washing and flowing the same. A soil washing method for collecting water with the coagulant.