In-situ remediation method for organic contaminated underground water

A technology of organic pollution and in-situ remediation, applied in water/sewage treatment, chemical instruments and methods, oxidized water/sewage treatment, etc., can solve the problems of groundwater acidification and heavy metal pollution, persulfate decomposition loss, consumption of oxidants, etc. Achieve the effect of avoiding acidification and heavy metal release secondary risks, avoiding secondary risks, and extending electrolysis time

Active Publication Date: 2013-02-06
CHINA UNIV OF GEOSCIENCES (WUHAN)
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Thermal activation requires heating the water to a higher temperature (such as 50 o C or above), alkali activation needs to adjust the pH to above 12, these two activation methods increase the repair cost and difficulty, S 2 o 8 2- Decomposition will inevitably occur before reaching the polluted area leading to loss
In contrast, the activation reaction conditions of Fe(II) (including chelated state) are milder, but the adsorption, oxidation, precipitation, etc. of Fe(II) during the transmission process will also cause losses, which greatly reduces the effective transmission distance. Moreover, the high concentration of Fe(II) in the initial injection stage will also consume the oxidant
In addition, S 2 o 8 2- After the activation reaction is completed, the pH of the system will drop to 2–3, causing the risk of heavy metal release in the underground environment
[0005] In the current persulfate oxidation repair, there are the following problems: ①The current activation method can only improve the oxidation activity of persulfate, once the persulfate is activated, the activity cannot be adjusted, let alone inhibited or eliminated. When the concentration of pollutants is low, this will inevitably cause a large amount of persulfate to be unusable and wasted
②The activator is mixed with the persulfate solution and then injected into the ground, which cannot realize the in-situ activation after the persulfate is transported to the polluted area
The decomposition of persulfate begins immediately after mixing with the activator, thus causing persulfate decomposition loss during injection into the ground and its transport in the underground environment, reducing the utilization of persulfate
③The sulfuric acid produced by self-decomposition after persulfate oxidation will reduce the pH of the groundwater in the remediation area to 2–3, which will cause the desorption and release of heavy metals adsorbed on the mineral surface and the total heavy metals in the mineral body in the underground environment, resulting in groundwater acidification and heavy metal pollution. secondary risk

Method used

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  • In-situ remediation method for organic contaminated underground water
  • In-situ remediation method for organic contaminated underground water
  • In-situ remediation method for organic contaminated underground water

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] In a sealed reactor to simulate the groundwater organic contamination area, add 410 mL of 52 mg / L trichlorethylene (TCE) and Na 2 S 2 o 8 , Na 2 S 2 o 8 The concentration is 12.5 times that of TCE, insert iron sheet (length × width × height = 76 × 9.5 × 3.2 mm) and titanium mesh (length × width × height = 85 × 15 × 1.8 mm) to act as two electrodes, two electrodes The distance between them is 2–30cm. Use wires to connect the electrodes to the two output terminals of the regulated DC power supply. After sealing, use the iron sheet as the positive electrode and apply a positive current of 50mA to activate the persulfate radicals, thereby realizing the organic matter oxidative degradation, the current value can be adjusted between 10–500mA during the degradation process, when the organic pollutant repair reaches 95% by mass, change iron as the negative electrode and apply a negative current of 50mA to inhibit the activity of persulfate radicals and the current during th...

Embodiment 1

[0021] In the sealed reactor to simulate organic pollution waters, add 410mL of 52mg / L trichlorethylene (TCE) and Na 2 S 2 o 8 , Na 2 S 2 o 8 The concentration is 12.5 times that of TCE, insert cast iron sheet (length × width × height = 76 × 9.5 × 3.2mm) and titanium mesh (length × width × height = 85 × 15 × 1.8 mm) to act as two electrodes, change after sealing The electrode polarity and current magnitude applied to the iron electrode, the removal effect of TCE is as follows figure 1 shown. Obviously, the degradation effect of TCE is accelerated with the increase of positive current, and is more significantly inhibited with the increase of negative current. When the negative current reaches -50mA, the degradation of TCE is almost completely inhibited.

Embodiment 2

[0023] Using the same reactor, in another set of experiments, the Na 2 S 2 o 8Concentration, which is 4 times the concentration of TCE, was continuously applied to the iron electrode at +100mA. Experimental results such as figure 2 shown by figure 2 It can be seen that the concentration of TCE and persulfate decreased significantly with time. After 30 minutes, TCE was completely degraded. Continue to apply +100mA current to the iron electrode, and the concentration of persulfate continued to decrease. After 50 minutes, the free heavy metal copper ions (Cu 2+ ) concentration began to decrease significantly. Depend on image 3 The corresponding pH and oxidation-reduction potential (ORP) changes showed that the pH of the aqueous solution began to increase significantly at 50 min, and reached the neutral range at 90 min.

[0024] The pollutant TCE in the above examples can be replaced by other substances in chlorinated solvents, benzene series and polycyclic aromatic hydro...

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PUM

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Abstract

The invention relates to an in-situ remediation method for organic contaminated underground water, comprising the specific steps that S2O8<2-> is injected to the organic contaminated region of underground water, an electrified iron electrode is inserted into the organic contaminated region, Fe (II) is provided by regulating the current magnitude of the iron electrode, when the iron electrode is electrified by positive current, the iron electrode partially is dissolved and generates Fe (II), so that S2O8<2-> is activated; when the iron electrode is electrified by negative current, the iron electrode is in the passivation state, so that the reaction activity of S2O8<2-> is restrained and even terminated; and when S2O8<2-> is used up, the iron electrode is used as the anode to continuously electrolyze, so as to provide Fe<2 / 3+> and OH<->, so that the pH of the system is increased to neutral state. The in-situ remediation method solves the difficult problems of in-situ regulation (enhancing and restraining) on the activity of peroxydisulfate and heavy metal release in the in-situ chemical oxidization remediation of peroxydisulfate.

Description

technical field [0001] The invention relates to an in-situ remediation method for organically polluted groundwater, in particular to regulate the persulfate (S 2 o 8 2- ) for the oxidation activity of organic pollutants to realize an in-situ remediation method for organically polluted groundwater, which belongs to the technical field of groundwater remediation. Background technique [0002] Ground water is widely used as a source of drinking water, but the ground water in many cities is polluted to varying degrees, especially the pollution caused by toxic organic substances such as chlorinated hydrocarbons, and the overall pollution situation is very serious. In groundwater pollution, the contamination of groundwater by small-area sites characterized by source pollution has received high attention due to the high degree of pollution and serious hazards. Therefore, it is of great significance to remediate the groundwater of the polluted site caused by toxic organic substan...

Claims

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Application Information

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IPC IPC(8): C02F1/461C02F1/72
Inventor 袁松虎廖鹏艾克元爱沙瓦比克
Owner CHINA UNIV OF GEOSCIENCES (WUHAN)
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