JP5284255B2 - Purification method for contaminated soil - Google Patents

Description

  The present invention relates to a method for purifying contaminated soil that can purify contaminated soil contaminated with PCBs or dioxins on site.

  As a method of purifying contaminated soil contaminated with PCB (polychlorinated biphenyl or polychlorinated biphenyl) or dioxins (polychlorinated dibenzopararadixin and polychlorinated dibenzofuran), a method using a heating and purifying apparatus that purifies the contaminated soil by heating. Is known (see Patent Document 1).

JP 2008-062168

However, in the purification method using the heating purification device described above, the contaminated soil must be transported to the place where the heating purification device is installed, and the contaminated soil is scattered during transportation, which incurs transportation costs and processing costs. There was a problem.
The present invention provides a method for purifying contaminated soil, which can purify contaminated soil at a contaminated site, and can solve the problems of scattering, transportation cost and treatment cost of contaminated soil.

In the method for purifying contaminated soil according to the present invention, the pressure wave generating unit of the pressure wave generating device is installed in the purification target portion in the contaminated soil contaminated with PCB or dioxins to generate a pressure wave, and then the target to be purified. After adding acid or alkali to the part, water was added, and then the enzyme solution was added to the part to be purified. In this way, the diatom shell covering the PCB and dioxins in the contaminated soil is destroyed by the pressure wave, the diatom shell becomes a water glass state by acid or alkali, and water is added to the purification target part. As a result, the water glass shell and water react to form Na ₂ S _i O ₃ and move downward in the ground, leaving PCBs and dioxins in their original positions. Thereafter, an enzyme solution is added to the portion to be purified where PCBs and dioxins remain, so that the enzyme in the enzyme solution decomposes the PCBs and dioxins. Therefore, according to the present invention, the contaminated soil can be purified at the contaminated site, and the problems of scattering of the contaminated soil, transportation cost, and processing cost can be solved.

The figure which shows the procedure of the purification method of contaminated soil. The figure which shows the mode in the contaminated soil by the purification method of contaminated soil. The figure which shows the taking-out method of an enzyme liquid. The figure which shows a discharge device.

FIG. 1; A method for purifying contaminated soil will be described with reference to FIG. First, as shown in FIG. 1A, a discharge electrode unit 6 of a discharge device 1 (pressure wave generator) described later in a contaminated soil 100 of a purification target portion 101 in a contaminated soil 100 contaminated with PCBs or dioxins. (Pressure wave generating part) is installed, and a discharge treatment is performed to discharge at the discharge electrode part 6 (see FIG. 1A). In this case, since PCBs and dioxins generally stay in the ground about 50 cm from the ground surface, it is preferable to install the discharge electrode portion 6 in the ground about 50 cm below the ground surface of the purification target portion 101. Due to the pressure wave generated by this discharge, the shell 103 (silicon dioxide (S _i O ₂ )) of the diatom 102 covering the PCB 100a and the dioxins 100b in the contaminated soil 100 is broken (see FIG. 2A). Next, the acid 104 or the alkali 105 is added to the purification target part 101 after the discharge treatment (see FIG. 1B). Thereby, shell 103 of diatom 102 will be in a water glass state (refer to Drawing 2 (b)). Water 106 is further added to the purification target portion 101 after the addition of the acid 104 or the alkali 105 (see FIG. 1C). As a result, the shell 103 in the water glass state and the water 106 react to form Na ₂ S _i O ₃ and move downward in the ground, and the PCB 100a and dioxins 100b remain in their original positions (FIG. 2 (c)). reference). That is, since PCBs and dioxins are not soluble in water, they are dissolved in the lipid part of the fossilized microalgae organic substance, which is a silt particle after the diatom shell is removed, and remains in the original position. Thereafter, the enzyme solution 107 is added to the purification target portion 101 where PCBs and dioxins remain (see FIG. 1D). Since the enzyme in the enzyme solution 107 destroys the PCB and dioxins of the purification target portion 101, the contaminated soil 100 is purified (see FIG. 2 (d)).

The enzyme solution 107 was prepared as follows, for example. The cultured bacteria are centrifuged with a centrifuge, and the precipitated bacteria are collected. A dense fungus group can be obtained by centrifuging with a centrifuge. Then, a discharge electrode part of the electrode device is placed in the obtained fungus group and discharged, and the cell membrane 111 of the fungus 110 is destroyed by a pressure wave due to the discharge, thereby containing an enzyme 108 covered with the cell membrane 111. The liquid 107 can be taken out (see FIG. 3). As the fungus, for example, a fungus obtained by inoculating a corn steep liquor (corn starch squeezed rice cake) diluted 40-fold with water to neutrality and culturing at 70 ° C. for 8 hours was used. As the fungus, any fungus having an enzyme that destroys PCBs and dioxins may be used. For example, Midosuji (GeoBacillus)
midousuji (American Type Culture Collection) ATCC 55926, ATCC 202050), genetically modified bacteria containing a Midosuji gene, and the like can be used.

  As shown in FIG. 4, the discharge device 1 includes an electrode device 2, a power supply device 3, and a connection body 30 for electrically connecting the electrode device 2 and the power supply device 3.

  The electrode device 2 includes a discharge electrode portion 6 composed of positive and negative electrodes 4; 5 arranged at an interval (discharge gap) g by an interval maintaining means 6A.

  The electrode 4; 5 is formed by one end of the electrode assembly 4A; 5A. The electrode structure 4A; 5A is formed of a so-called coated wire having a wire diameter of about 4 mm to 5 mm, for example, in which a conductor wire such as a copper wire having a wire diameter of about 2 mm to 3 mm is coated with a resin such as vinyl resin. In this case, the electrodes 4; 5 are formed by one end of the conductor wire exposed at one end of the covered wire. A positive electrode terminal 4 a is provided at the other end of the electrode structure 4 </ b> A whose one end is the positive electrode 4, and a negative electrode terminal 5 a is provided at the other end of the electrode structure 5 </ b> A whose one end is the negative electrode 5.

  By bending one end (electrode 4; 5) side of the electrode structure 4A; 5A in a straight line at a right angle from the straight state, L-shaped one end portions having a right angle relationship with each other are formed. One end (electrode 4; 5) of the bent portion 4B; 5B (hereinafter referred to as an electrode portion) is arranged with a gap g therebetween, and the positive and negative electrodes 4; 5 with the gap g held by the gap maintaining means 6A. A discharge electrode portion 6 made of is formed. The spacing maintaining means 6A is formed of an insulator, for example, a pair of sandwiching bodies provided at both ends with sandwiching bodies 6d; 6d that are sandwiched and attached to the electrode portions 4B; 6d; the interval b between 6d is maintained by the interval maintaining member 6e. The interval maintaining means 6A is composed of a rod-shaped insulator (not shown) that connects the electrode portions 4B; 5B to each other so that the electrodes 4; May be.

The power supply device 3 includes a booster device 12 and a pulse power output device 13.
The booster 12 includes a power supply voltage input unit 14A, a booster circuit 15 including a transformer (not shown), and an output unit 14.
The booster circuit 15 inputs, for example, a three-phase AC 200V power supply voltage via a power cable 14C connected to the power supply voltage input unit 14A to generate a voltage of DC 20 kV to 50 kV, for example, and generates the generated voltage of DC 20 kV to 50 kV. Output from the output unit 14. The output unit 14 includes a positive terminal 14a and a negative terminal 14b.

  The pulse power output device 13 includes an input terminal 16, a charging circuit 17, and an electrode connection unit 18 as an output unit. The input terminal 16 includes a positive terminal 16a and a negative terminal 16b. The electrode connecting portion 18 includes a positive terminal 18a and a negative terminal 18b. The charging circuit 17 includes a positive electrode line 17a, a negative electrode line 17b, a capacitor 20, and switches 21; 22. A switch 21 and a switch 22 are connected in series to the positive electrode line 17a. One end of the positive electrode line 17 a is connected to the positive electrode terminal 16 a of the input terminal 16, and the other end of the positive electrode line 17 a is connected to the positive electrode terminal 18 a of the electrode connection part 18. One end of the negative electrode wire 17 b is connected to the negative electrode terminal 16 b of the input terminal 16, and the other end of the negative electrode wire 17 b is connected to the negative electrode terminal 18 b of the electrode connection portion 18. The capacitor 20 is connected to a connection point between the switch 21 and the switch 22 in the positive electrode line 17a and the negative electrode line 17b. That is, the capacitor 20 is connected in parallel to the positive electrode line 17a and the negative electrode line 17b. The switch 21 is a switch for charging the capacitor 20 with the voltage supplied from the booster 12, and the switch 22 is a switch for discharging the charge charged in the capacitor 20 and outputting it to the electrode device 2 via the electrode connection unit 18. It is. Although not shown, the charging circuit 17 is grounded.

  The connection body 30 includes a connection cable 31, an input-side connector 32 provided at one end of the connection cable 31, and an output-side connector 33 provided at the other end of the connection cable 31. The input-side connector 32 includes a positive terminal 32 a and a negative terminal 32 b that are connected to each of the positive terminal 18 a and the negative terminal 18 b of the electrode connection portion 18 of the power supply device 3. The output side connector 33 includes a positive electrode terminal 33a connected to the positive electrode terminal 4a of the electrode structure 4A and a negative electrode terminal 33b connected to the negative electrode terminal 5a of the electrode structure 5A.

  Next, a method for using the discharge device 1 will be described. While connecting the input side connector 32 of the connection body 30 and the electrode connection part 18 of the power supply device 3, the output side connector 33 of the connection body 30 and the electrode structure 4A; 5A are electrically connected. By setting both the switch 21 and the switch 22 of the power supply device 3 to the non-conductive state and electrically connecting the power supply device 3 to the AC 200V power supply via the power supply cable 14C, the booster device via the power supply cable 14C is provided. 12 is supplied with AC 200V power, and the AC 200V is boosted by the booster circuit 15 to, for example, DC 20 kV to 50 kV. When the switch 21 is turned on, charge is accumulated in the capacitor 20. After the electric charge is accumulated in the capacitor 20, the switch 22 is turned on. As a result, a voltage is applied to the electrodes 4; 5 of the discharge electrode portion 6 of the electrode device 2 to generate a discharge between the electrodes 4;

  Instead of the electrode device 2, an electrode device 2A shown in FIG. 4 may be used. The electrode device 2 </ b> A is provided, for example, on a rod-shaped inner conductor 73 as one electrode such as a + electrode, a cylindrical insulator 74 that covers the outer periphery of the inner conductor 73, and an outer periphery of the insulator 74. It is constituted by an outer conductor 75 as the other electrode such as an electrode. That is, the electrode device 2A is a coaxial electrode having a configuration in which the inner conductor 73, the insulator 74, and the outer conductor 75 are arranged coaxially. The outer conductor 75 constitutes a plurality of floating electrodes 76; 76... Spaced apart in the direction along the center line of the inner conductor 73. The floating electrode is an electrode that is electrically insulated from the power supply side. A leading end side discharge gap 77 is formed between the leading end portion 73t of the internal conductor 73 protruding from the leading end 74t of the insulator 74 and exposed, and the leading end portion 76t of the floating electrode 76 closest to the leading end portion 73t. An intermediate discharge gap 78 that generates a discharge is formed between the end portions 76s and the end portions 76s of the floating electrodes 76 that perform the discharge. A plurality of intermediate discharge gaps 78 are formed. The discharge electrode portion 6 is formed by the inner conductor 73 in which the front end side discharge gap 77 and the intermediate side discharge gap 78 are maintained and the plurality of floating electrodes 76.

  According to the embodiment, the contaminated soil can be purified at the contaminated site, and the problems of scattering of the contaminated soil, transportation cost, and processing cost can be solved.

  Although the discharge device is used in the above, other pressure wave generators such as an ultrasonic device may be used as long as the device generates pressure waves.

1 discharge device (pressure wave generator), 6 discharge electrode part (pressure wave generator),
100 contaminated soil, 101 part to be purified, 104 acid, 105 alkali, 106 water, 107 enzyme solution.

Claims (1)

The pressure wave generator of the pressure wave generator was installed in the target area of the contaminated soil contaminated with PCBs and dioxins to generate pressure waves and destroyed the diatom shells covering the PCBs and dioxins . After that, the diatom shell destroyed by adding acid or alkali to the part to be purified is made into a water glass state, then water is added to cause the water glass state shell to react with water and move down into the ground as Na ₂ S _i O ₃ A method for purifying contaminated soil, comprising: adding an enzyme solution to the portion to be purified and then decomposing PCB or dioxins with the enzyme .

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