TREATMENT OF CONTAMINATED SOIL AND WATER

Abstract

A method of remediation of polluted soil or water by chemical oxidation of organic pollutants, including adding to the soil or water separate or joined streams of aqueous iron salt solution and an acid, and injecting aqueous hydrogen peroxide solution and oxygen-containing gas to the soil or water, such that said aqueous streams and the oxygen-containing gas mix with one another in the soil or water in an acidic environment.

Claims

1. A method of remediation of polluted soil or water by chemical oxidation of organic pollutants, comprising adding to the soil or water separate or joined streams of aqueous iron salt solution and an acid, and injecting aqueous hydrogen peroxide solution and oxygen-containing gas to the soil or water, such that said aqueous streams and the oxygen-containing gas mix with one another in the soil or water in an acidic environment.

2. The method according to claim 1, comprising ex-situ, on site or in-situ chemical oxidation of polluted soil.

3. The method according to claim 2, comprising successively adding to the soil a first aqueous stream that contains ferrous salt and a mineral acid and a second aqueous stream which contains hydrogen peroxide.

4. The method according to claim 2, wherein the injection of the oxygen-containing gas to the soil starts simultaneously with, or after, the addition of the hydrogen peroxide stream.

5. The method according to claim 4, comprising addition of hydrogen peroxide to aqueous ferrous salt solution-soaked soil under acidic environment with injection of oxygen-containing gas stream into the soil, and allowing decontamination of pollutants to proceed under said acidic environment over a period of time.

6. The method according to claim 5, wherein a stream of aqueous alkali hydroxide solution is added to the soil after the lapse of said period of time, with addition of hydrogen peroxide and injection of oxygen-containing gas.

7. The method according to claim 2, wherein the soil is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

8. The method according to claim 7, wherein the soil is contaminated with one or more of crude oil, diesel oil, polychlorinated biphenyls and TPH.

9. The method according to claim 1 for remediation of polluted water, comprising either the pumping of the polluted water and treatment by chemical oxidation; or in situ chemical oxidation of polluted water.

10. The method according to claim 9, comprising the steps of: pumping groundwater to an above-ground reactor; treating the water in the reactor by a two-stage chemical oxidization, wherein the first stage includes addition to the water of a ferrous salt, an acid, hydrogen peroxide with simultaneous injection of the oxygen-containing gas; and the second stage includes addition of alkali hydroxide and hydrogen peroxide with simultaneous injection of the oxygen-containing gas; and discharging the treated water from the reactor and reinjecting the treated water to the groundwater.

11. The method according to claim 9, comprising the steps of: introducing to groundwater a ferrous salt, an acid, hydrogen peroxide with simultaneous injection of the oxygen-containing gas, followed by addition of alkali hydroxide and hydrogen peroxide with simultaneous injection of the oxygen-containing gas.

12. The method according to claim 9, wherein the groundwater is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

13. The method according to claim 12, wherein the groundwater is polluted with one or more pollutants selected from the group consisting of chlorinated solvents, diesel fuel and crude oil.

14. The method according to claim 3, wherein the injection of the oxygen-containing gas to the soil starts simultaneously with, or after, the addition of the hydrogen peroxide stream.

15. The method according to claim 3, wherein the soil is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

16. The method according to claim 4, wherein the soil is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

17. The method according to claim 5, wherein the soil is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

18. The method according to claim 6, wherein the soil is contaminated with one or more pollutants selected from the group consisting of polychlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents, pharmaceutical leftovers, petroleum products such as petroleum, gasoline, crude oil, diesel fuel, aviation fuel, jet fuel, kerosene, liquefied petroleum gases, petrochemical feedstocks and any mixture thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 shows a proposed reaction mechanism for the ‘oxygen-augmented Fenton-like reaction’.

[0034] FIG. 2 illustrates ex situ chemical oxidation of excavated polluted soil based on ‘oxygen-augmented Fenton-like reaction’.

[0035] FIG. 3 illustrates in situ chemical oxidation of polluted soil, based on ‘oxygen-augmented Fenton-like reaction’.

[0036] FIGS. 4 and 5 show the results of GC-FID analysis for the experiment of Example 1 (soil treatment), demonstrating conversion of crude oil and diesel, respectively, achieved by the method of the invention (top section: polluted sample; lower section: treated sample).

[0037] FIG. 6 shows the results of GC-FID analysis for the experiment of Example 2 (soil treatment), demonstrating conversion of polychlorinated biphenyls, achieved by the method of the invention (top section: polluted sample; lower section: treated sample).

[0038] FIG. 7 is a bar diagram illustrating the results of a comparative study.

[0039] FIG. 8 shows the results of GC-FID analysis for the experiment of Example 4 (soil treatment), demonstrating conversion of TPH, achieved by the method of the invention (top section: polluted sample; lower section: treated sample).

[0040] FIG. 9 shows the results of GC-FID analysis for the experiment of Example 5 (water treatment), demonstrating conversion of crude oil and diesel, achieved by the method of the invention (top section: polluted sample; lower section: treated sample).

[0041] FIG. 10 shows the results of GC-FID analysis for the experiment of Example 6 (water treatment), demonstrating conversion of chlorinated solvents and diesel, achieved by the method of the invention (top section: polluted sample; lower section: treated sample).

[0042] FIG. 11 illustrates groundwater remediation by integration of the ‘oxygen-augmented Fenton-like reaction’ into ‘pump and treat’ technology.

[0043] FIG. 12 illustrates in situ chemical oxidation of groundwater based on the ‘oxygen-augmented Fenton-like reaction’.

DETAILED DESCRIPTION

Examples

Example 1

Soil Treatment—Removal of Crude Oil and Diesel

[0044] The experimental set-up consists of 1000 mL adiabatic glass reactor equipped with a magnetic stirrer and fitted with 100% oxygen cylinder, with flow rate of 1 ml/min or with 100% air cylinder (Maxima, LTD). The Purity level of the gas in both gas cylinders is 99%.

[0045] The reactor was charged with a soil sample (1 g) that was artificially contaminated with a mixture consisting of crude oil and diesel, to reach 1% (10,000 ppm) total contamination level. A volume of 0.7 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of FeSO.sub.4.7H.sub.2O dissolved in 0.7 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity).

[0046] Thirty minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was absorbed by the soil sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. The reaction proceeded for two hours under stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 1 ml/min.

[0047] The soil at the end of the process was extracted with 1 ml of toluene and measured by GC-FID (Thermo Ltd. RESTECK. FAMEWAX™ 30 m, 0.32 mm ID, 0.25 μm) as shown in FIGS. 4 and 5. The results indicate 92% and 90% conversion of the crude oil and diesel contaminants, respectively.

Example 2

Soil Treatment—Removal of Polychlorinated Biphenyls

[0048] An experimental set-up similar to that of previous example was used. The reactor was charged with a soil sample (1 g) that was taken from PCBs polluted site. The contamination level was estimated to be about 2 ppm. A volume of 0.7 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of solid FeSO.sub.4.7H.sub.2O dissolved in 0.7 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity).

[0049] Thirty minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was absorbed by the soil sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. The reaction proceeds for two hours under stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 1 ml/min.

[0050] Next, 0.1 mL of aqueous sodium hydroxide solution (1% by weight concentration) was added under the same continuous stirring, added H.sub.2O.sub.2 and aeration conditions described above over additional one hour.

[0051] The soil at the end of the process was extracted with 1 ml of toluene and measured by GC-FID (Thermo Ltd. RESTECK. FAMEWAX™ 30 m, 0.32 mm ID, 0.25 μm) as shown in FIG. 6. The results indicate 97% conversion of the PCBs pollutants that contaminated the soil sample.

Example 3

Soil Treatment—Removal of Polychlorinated Biphenyls Comparative Example

[0052] An experimental set-up similar to that of previous examples was used. Four different soil treatment were tested, in each of them the reactor was charged with a soil sample (1 g) that was taken from PCBs polluted site. The contamination level was estimated to be about 2 ppm.

[0053] The four different soil treatment procedures are detailed herein below: [0054] A. The experimental conditions and reagent amounts were identical to those utilized in Example 2: A volume of 0.7 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of solid FeSO.sub.4.7H.sub.2O dissolved in 0.7 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity). Thirty minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was absorbed by the soil sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. Next, 0.1 mL of aqueous sodium hydroxide solution (1% by weight concentration) was added to the reactor over additional one hour. This process took place under constant stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 1 ml/min and added 14202. [0055] B. The experimental conditions and reagent amounts were identical to those utilized in A, however, the process took place with no aeration, i.e. no air or oxygen injection into the reactor. [0056] C. A volume of 0.7 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of solid FeSO.sub.4.7H.sub.2O dissolved in 0.7 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity). Thirty minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was absorbed by the soil sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. This process was done with no aeration, i.e. no air or oxygen injection into the reactor, and no addition of alkali hydroxide. [0057] D. The conditions of the process were reproduced according to the publication Journal of Environmental Science and Health Part A (2009) 44, 1120-1126, in which 4.6 mL of hydrogen peroxide solution (35%) and 0.4 ml of the Fe.sub.2(SO.sub.4).sub.3 solution were reacted with 1 gr of soil, said comparative reaction took place for 4 hours.

[0058] The soil at the end of each process (A to D) was extracted with 1 mL of toluene and measured by GC-FID. The results are depicted in FIG. 7 in the form of a bar diagram; bars are indicated by the letters A-D, respectively. Clearly the method of the invention (A) emerges superior, achieving better decontamination effect, that is, practically almost full decontamination (expressed as conversion percentage; 97%, 83%, 69% and 23, for the A-D experiments, respectively).

Example 4

Soil Treatment—Removal of TPH

[0059] An experimental set-up similar to that of previous example was used. The reactor was charged with a soil sample (1 g) that was taken from TPHs polluted site. The contamination level was estimated to be about 1,600 ppm. A volume of 0.7 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of solid FeSO.sub.4.7H.sub.2O dissolved in 0.7 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity).

[0060] Thirty minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was absorbed by the soil sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. The reaction proceeds for two hours under stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 1 ml/min.

[0061] Next, 0.1 mL of aqueous sodium hydroxide solution (1% by weight concentration) was added under the same continuous stirring, added H.sub.2O.sub.2, and aeration conditions described above over additional one hour.

[0062] The soil at the end of the process was extracted with 1 ml of dichloromethane and measured by GC-FID (Thermo Ltd. RESTECK. FAMEWAX™ 30 m, 0.32 mm ID, 0.25 μm) as shown in FIG. 8. The results indicate 91% conversion of the TPHs pollutants that contaminated the soil sample.

Example 5

Groundwater/Wastewater Treatment—Removal of Crude Oil and Diesel

[0063] The experimental set-up consists of 2000 mL adiabatic glass reactor equipped with a magnetic stirrer and fitted with 100% oxygen cylinder, with flow rate of 0.5 ml/min or with 100% air cylinder (Maxima, LTD). The Purity level of the gas in both gas cylinders is 99%.

[0064] The reactor was charged with a contaminated water sample (500 mL) that was contaminated with a mixture consisting of crude oil and diesel, to reach 0.7% (7,000 ppm) total contamination level. A volume of 0.1 mL of a separately prepared solution of solid ferrous sulfate heptahydrate and sulfuric acid (0.1 g of FeSO.sub.4.7H.sub.2O dissolved in 0.1 ml of water to which 0.2 of H.sub.2SO.sub.4 98% was added) was fed to the glass beaker under stirring (100 rpm stirring velocity).

[0065] Ten minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was homogeneously dissolved in the sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. The reaction proceeds for four hours under stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 0.5 ml/min.

[0066] Next, 0.1 mL of aqueous sodium hydroxide solution (1% by weight concentration) was added under the same continuous stirring, added H.sub.2O.sub.2, and aeration conditions described above over additional one hour.

[0067] The water at the end of the process was extracted with 100 ml of dichloromethane and measured by GC-FID (Thermo Ltd. RESTECK. FAMEWAX™ 30 m, 0.32 mm ID, 0.25 μm) as shown in FIG. 9. The results indicate 99% conversion of the contaminated water.

Example 6

Groundwater/Wastewater Treatment—Removal of Chlorinated Solvents and Diesel

[0068] The experimental set-up consists of 2000 mL adiabatic glass reactor equipped with a magnetic stirrer and fitted with 100% oxygen cylinder, with flow rate of 0.5 ml/min or with 100% air cylinder (Maxima, LTD). The Purity level of the gas in both gas cylinders is 99%.

[0069] The reactor was charged with a contaminated water sample (500 mL) that was contaminated with a mixture consisting of chlorinated solvents and diesel, to reach 1% (10,000 ppm) total contamination level. A volume of 0.1 mL of a separately prepared solution of ferrous sulfate heptahydrate and sulfuric acid (0.1 g of FeSO.sub.4.7H.sub.2O dissolved in 0.1 ml of water to which 0.2 μL of H.sub.2SO.sub.4 98% was added) is fed to the glass beaker under stirring (100 rpm stirring velocity).

[0070] Ten minutes elapsed before the addition of hydrogen peroxide began, during which period the aqueous ferrous solution was homogeneously dissolved in the sample. Hydrogen peroxide (0.3 mL of 35% solution) was then added slowly to the reactor. The reaction proceeds for four hours under stirring and continuous aeration by means of injecting an air stream to the reactor at a flow rate of 0.5 ml/min.

[0071] Next, 0.1 mL of aqueous sodium hydroxide solution (1% by weight concentration) was added under the same continuous stirring, added H.sub.2O.sub.2 and aeration conditions described above over additional one hour.

[0072] The water at the end of the process was extracted with 100 ml of dichloromethane and measured by GC-FID (Thermo Ltd. RESTECK. FAMEWAX™ 30 m, 0.32 mm ID, 0.25 μm) as shown in FIG. 10. The results indicate 98.5% conversion of the contaminated water.

[0073] While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.