JP2021146326A5 - - Google Patents

Description

Furthermore, in the wet cleaning method for contaminated soil according to one aspect of the present invention, the heat treatment of the adsorbent may be thermal decomposition of the pollutant in a pyrolysis furnace, and the adsorbent may be granular activated carbon.

In the contaminated soil wet cleaning system 1 according to the present embodiment, only the adsorbent separated by the adsorbent separation device 5 is heat-treated by the heat treatment device 6. The water containing PFOS and PFOA analogous compounds separated from the clean granules may be heat-treated by the heat treatment device 6 . However, in this case, since it is necessary to sufficiently heat the water, it is expected to be disadvantageous in terms of energy cost.

Therefore, in step S23, a water jet process is performed to crush the above-mentioned small-diameter particles into sand and fine particles using water flow, and to separate the fine particles adhering to the surface of the sand. This water jet treatment may be simply a treatment of spraying high-pressure water, or a high-speed jet flow by applying high pressure to the slurry itself, which is a mixture of sand, fine particles, and water, which is called collision jet (registered trademark) treatment. and collide with an appropriate target, or by colliding the jets with each other. As a result of this treatment, the slurry consisted of clean sand from which fine granules and PFOS and PFOA-related compounds were removed, crushed fine granules adsorbing PFOS and PFOA-related compounds, and water in which PFOS and PFOA-related compounds were dissolved. It is a mixture of

Since the exhaust gas may contain hydrogen fluoride gas of high concentration and cannot be discharged into the atmosphere as it is, in step S6, such exhaust gas is purified, that is, harmful substances are removed from the waste gas. Substance removal is performed by the exhaust gas cleaning device 7 .

In order to remove other pollutants contained in the exhaust gas, the exhaust gas purification device 7 may include devices such as a dust remover and a desulfurization device. Further, the exhaust gas purifying device 7 may be provided with a heat exchanger so that the temperature of the exhaust gas when being treated in each pollutant removal device becomes appropriate. The clean exhaust gas cleaned by the exhaust gas cleaner 7 is released into the atmosphere, and the fluoride compounds, dust, sulfides, etc. dissolved or fixed in the aqueous liquid are appropriately treated or reused. is done.

The polluted sludge, which is the residue after the adsorbent is separated in step S4 , is dehydrated in step S7 and separated into clean granules and water in which a small amount of PFOS and PFOA-related compounds are dissolved. The dehydrated water is recycled as water added during separation of clean gravel in step S2.

Claims (8)

A wet cleaning method for soil contaminated with contaminants containing at least one of PFOS and PFOA-related compounds,
separating the contaminated soil into clean gravel and contaminated mud;
A step of mixing an adsorbent larger than a predetermined particle size with the contaminated mud;
A step of separating fine particles in the polluted mud and the adsorbent;
heat-treating the adsorbent;
A method for wet cleanup of contaminated soil containing 2. The method for wet cleaning of contaminated soil according to claim 1, wherein the separation of the contaminated mud is performed using a difference in particle size between the fine particles and the adsorbent. 3. The wet cleanup method for contaminated soil according to claim 1 or 2, wherein the heat treatment of the adsorbent is thermal decomposition of the pollutants in a pyrolysis furnace, and the adsorbent is granular activated carbon. 4. The wet cleaning method for contaminated soil according to claim 3, further comprising a step of removing hydrogen fluoride gas from waste gas generated by said heat treatment. The step of separating the contaminated soil into clean gravel and contaminated mud,
a step of separating clean gravel from the contaminated soil;
A step of stripping the pollutants and fine grains from the sand in the contaminated soil after gravel separation by a water jet;
a step of separating clean sand from the contaminated soil after gravel separation;
The wet cleaning method for contaminated soil according to any one of claims 1 to 4, comprising The contaminated soil according to any one of claims 1 to 5, wherein in the step of heat-treating the adsorbent, the waste to which PFOS and PFOA-related compounds are attached, or the waste containing fluorine-containing organic compounds is simultaneously heat-treated. Wet cleaning method. a device for supplying contaminated soil with contaminants containing at least one of PFOS and PFOA analogues;
a clean gravel separator for separating the contaminated soil into clean gravel and contaminated mud;
A mixing device for mixing an adsorbent larger than a predetermined particle size with the contaminated mud;
an adsorbent separation device for separating fine particles in the polluted mud and the adsorbent;
a heat treatment device for heat-treating the adsorbent;
Wet cleanup systems for contaminated soil, including The supply device, the clean gravel separation device, the mixing device, the adsorbent separation device and the heat treatment device are portable,
The wet cleaning system for contaminated soil according to claim 7.