Method for remediating groundwater organic contamination by in-situ reaction zone

Patent metadata

Field	Value
Publication number	US-11897797-B2
Application number	US-202318198994-A
Country	US
Kind code	B2
Filing date	May 18, 2023
Priority date	May 19, 2022
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

The present disclosure belongs to the field of environmental protection and relates to a method for remediating groundwater chlorophenols organic contamination. The method includes determining a location of a contamination source; setting up an injection well based on the location of the contamination source; and injecting a remediation reagent into groundwater in a to-be-remediated region through the injection well so as to degrade chlorophenols organic contamination in the groundwater in the to-be-remediated region.

First claim

The invention claimed is:

1. A method for remediating groundwater chlorophenols organic contamination, comprising the following steps of:
step S1. determining a location of a contamination source;
step S2. setting up an injection well in upstream in a flowing direction of the groundwater of the contamination source; and
step S3. degrading chlorophenols organic contamination in groundwater in the to-be-remediated region by injecting a remediation reagent into groundwater in a to-be-remediated region through the injection well;
wherein,
the step S3 comprises: detecting a flow rate of the groundwater in the to-be-remediated region,
when the flow rate is greater than 4 m/d, the remediation reagent comprises sulfidated nanoscale zero-valent iron and hydrogen peroxide, wherein an iron-sulfur ratio in the sulfidated nanoscale zero-valent iron is 15; and
when the flow rate is smaller than or equal to 4 m/d, the remediation reagent comprises sulfidated nanoscale zero-valent iron modified by sodium carboxymethylcellulose and hydrogen peroxide, wherein the sodium carboxymethylcellulose in the sulfidated nanoscale zero-valent iron modified by sodium carboxymethylcellulose is used at a concentration of 1.0 g·L −1 .

2. The method of claim 1 , wherein the sulfidated nanoscale zero-valent iron is prepared by the following steps:
adding absolute ethyl alcohol into a prepared FeSO 4 solution for stirring, dropwise adding a NaOH solution with dissolved NaBH 4 , and then reacting to obtain nanoscale zero-valent iron; and
adding the obtained nanoscale zero-valent iron into a prepared Na 2 S solution, obtaining a sulfidated nanoscale zero-valent iron suspension liquid through ultrasonic, and thereby preparing the sulfidated nanoscale zero-valent iron.

3. The method of claim 1 , wherein the sulfidated nanoscale zero-valent iron modified by sodium carboxymethylcellulose is prepared by the following steps:
adding the sulfidated nanoscale zero-valent iron into a debubbled sodium carboxymethylcellulose solution, performing ultrasonic dispersion, then freezing and shaking well to obtain a sulfidated nanoscale zero-valent iron suspension liquid modified by sodium carboxymethylcellulose, and thereby obtaining the sulfidated nanoscale zero-valent iron modified by sodium carboxymethylcellulose after magnetic separation.

4. The method of claim 1 , wherein when the flow rate is greater than 4 m/d, an amount of the added sulfidated nanoscale zero-valent iron is 0.5 g per liter of groundwater, a concentration of H 2 O 2 is 3 mM, and pH is 4.

5. The method of claim 1 , wherein when the flow rate is smaller than or equal to 4 m/d, an amount of the added sulfidated nanoscale zero-valent iron modified by sodium carboxymethylcellulose is 0.6 g per liter of groundwater, a concentration of H 2 O 2 is 5 mM, and pH is 4.

6. The method of claim 1 , wherein before injecting the remediation reagent, a concentration of SO 4 2− in the groundwater in the to-be-remediated is adjusted to a range of 1 mM to 100 mM, and a concentration of is adjusted to a range of 1 mM to 10 mM.

7. The method of claim 1 , wherein, a plurality of monitoring wells are arranged in a to-be-remediated region, when the remediation reagent is injected at interval time, a next injection node of the remediation reagent is determined through change conditions of one or more monitored parameters of a pollutant concentration, a total iron concentration distribution and a pH value in the groundwater monitored in real time by each monitoring well, wherein the injection node is at least at a moment when any one or more monitored parameters have an inflection point in a range curve in data obtained from all the monitoring wells.

8. The method of claim 7 , wherein at least one processing unit capable of receiving real-time monitored data of each monitoring well is configured to analyze the injection node of the remediation reagent, wherein, a monitoring frequency that the processing unit obtains the real-time monitored data of each monitoring well is adjusted at least in a periodic fluctuation mode based on the injection node of the remediation reagent, and a peak value of the monitoring frequency can be set higher than a peak value of a previous fluctuation period.

9. The method of claim 7 , wherein S-nZVI or CMC-S-nZVI in the remediation reagent can be recycled repeatedly under a condition of controlling a degradation rate of a pollutant to be at least greater than 70%.

10. The method of claim 2 , wherein before injecting the remediation reagent, a concentration of SO 4 2− in the groundwater in the to-be-remediated is adjusted to a range of 1 mM to 100 mM, and a concentration of Cl − is adjusted to a range of 1 mM to 10 mM.

11. The method of claim 3 , wherein before injecting the remediation reagent, a concentration of SO 4 2− in the groundwater in the to-be-remediated is adjusted to a range of 1 mM to 100 mM, and a concentration of Cl −1 is adjusted to a range of 1 mM to 10 mM.

12. The method of claim 4 , wherein before injecting the remediation reagent, a concentration of SO 4 2− in the groundwater in the to-be-remediated is adjusted to a range of 1 mM to 100 mM, and a concentration of Cl − is adjusted to a range of 1 mM to 10 mM.

13. The method of claim 5 , wherein before injecting the remediation reagent, a concentration of SO 4 2− in the groundwater in the to-be-remediated is adjusted to a range of 1 mM to 100 mM, and a concentration of Cl − is adjusted to a range of 1 mM to 10 mM.

14. The method of claim 2 , wherein before injecting the remediation reagent, a concentration of HCO 3 − in the groundwater is less than 10 mM, and a concentration of NO 3 − is less than 10 mM.

15. The method of claim 3 , wherein before injecting the remediation reagent, a concentration of HCO 3 − in the groundwater is less than 10 mM, and a concentration of NO 3 − is less than 10 mM.

16. The method of claim 4 , wherein before injecting the remediation reagent, a concentration of HCO 3 − in the groundwater is less than 10 mM, and a concentration of NO 3 − is less than 10 mM.

17. The method of claim 5 , wherein before injecting the remediation reagent, a concentration of HCO 3 − in the groundwater is less than 10 mM, and a concentration of NO 3 − is less than 10 mM.

Assignees

• Univ Chengdu Technology

Inventors

• Pu Shengyan
• Ma Hui
• Yu Dong
• Luo Dongyuan
• Du Junyan
• Ni Xinxin
• Miao Zhu
• Wang Yu

Classifications

• C02F1/705 Primary

  Reduction by metals · CPC title

• B09C1/002 Primary

  involving in-situ ground water treatment · CPC title

• C02F1/722 Primary

  Oxidation by peroxides · CPC title

• C02F2101/345

  Phenols · CPC title

• C02F2101/36

  containing halogen · CPC title