Search

CN-121972506-A - Method for repairing chromium-polluted soil by cooperation of microorganisms and natural iron-containing minerals

CN121972506ACN 121972506 ACN121972506 ACN 121972506ACN-121972506-A

Abstract

The application discloses a method for restoring chromium-polluted soil by utilizing microorganism to cooperate with natural iron-containing minerals, which comprises the steps of mixing natural iron-containing minerals into chromium-polluted soil, standing for a plurality of days, adding mixed bacteria into an obtained system, standing for reduction reaction, reducing high-valence iron and high-valence sulfur in the system into ferrous iron and divalent sulfur, forming a low oxidation-reduction potential environment in the system, adding chromium-reducing bacteria into the system in the low oxidation-reduction potential environment, standing for reduction of hexavalent chromium, obtaining trivalent chromium, carrying out mineralization reaction on the trivalent chromium and the ferrous iron, obtaining chromite-like products, and restoring the chromium-polluted soil. According to the method provided by the application, the natural iron-containing mineral, the mixed bacteria and the chromium-reducing bacteria cooperatively reduce and mineralize hexavalent chromium, so that the mineralization stable restoration of hexavalent chromium is realized, the problems of unstable chromium products, easiness in re-dissolution and re-pollution and the like after the traditional restoration are solved, and the method has the advantages of short restoration period, low construction cost and long-acting stable effect, and the problem of secondary pollution in the treatment process is avoided.

Inventors

  • LI HONGXIA
  • Cui xinglan
  • WANG LEI
  • SHI XINYUE

Assignees

  • 有研资源环境技术研究院(北京)有限公司

Dates

Publication Date
20260505
Application Date
20260324

Claims (10)

  1. 1. A method for repairing chromium-contaminated soil by microorganisms in combination with natural iron-containing minerals, the method comprising: mixing natural iron-containing minerals into chromium-contaminated soil, standing for several days, adding mixed bacteria into the obtained system, standing for reduction reaction, reducing high-valence iron and high-valence sulfur in the system into ferrous iron and ferrous sulfur, and forming a low oxidation-reduction potential environment in the system; adding chromium reducing bacteria into a system in a low oxidation-reduction potential environment, standing and reducing hexavalent chromium to obtain trivalent chromium, and carrying out mineralization reaction on the trivalent chromium and the ferrous iron to obtain a chromite-like product, so as to repair the chromium-polluted soil; wherein the mixed bacteria are formed by compounding sulfate reducing bacteria EM2 and alicyclic acid bacillus.
  2. 2. The method for restoring chromium-contaminated soil by utilizing the microorganism to cooperate with natural iron-containing minerals according to claim 1, wherein the sulfate reducing bacteria EM2 are preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2017645; The chromium-reducing bacteria are selected from at least one of microbacterium GRINML SWG, chromium-reducing bacillus GRINML SWG and fens-type fiber microbacterium GRINML SWG; Wherein the microbacterium GRINML SWG1 is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021992; The chromium-reduced bacillus GRINML SWG is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021991; The Fenne type fiber microzyme GRINML SWG is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021990.
  3. 3. The method for restoring chromium-contaminated soil by utilizing microorganisms in combination with natural iron-containing minerals according to claim 1, wherein said method further comprises: And in the step of standing and reducing hexavalent chromium, monitoring the oxidation-reduction potential of a reduction system, and supplementing the mixed bacteria into the reduction system when the oxidation-reduction potential is higher than zero potential so as to recover the oxidation-reduction potential in the reduction system to be lower than zero potential.
  4. 4. The method for restoring chromium-contaminated soil in coordination with natural iron-containing minerals of claim 1, wherein said natural iron-containing minerals are selected from at least one of natural pyrite, natural magnetite, and natural hematite.
  5. 5. The method for restoring chromium-contaminated soil by cooperating microorganisms with natural iron-containing minerals according to claim 1 or 4, wherein the natural iron-containing minerals have a particle size of 63.5 μm to 254 μm; the addition amount of the natural iron-containing minerals accounts for 0.2% -1% of the mass of the chromium-polluted soil.
  6. 6. The method for restoring chromium-contaminated soil by utilizing microorganisms in combination with natural iron-containing minerals according to claim 1, wherein said standing for several days is not less than 3 days and not more than 7 days.
  7. 7. The method for restoring chromium-contaminated soil by utilizing the microorganism to cooperate with natural iron-containing minerals according to claim 1, wherein the mixed bacteria are obtained by mixing sulfate-reducing bacteria EM2 and alicyclic acid bacillus in a volume ratio of 1:2-2:1, and then placing the mixed bacteria in an incubator at a temperature of 25-35 ℃ for expansion culture for 3-4 days.
  8. 8. The method for restoring chromium-contaminated soil by utilizing microorganisms to cooperate with natural iron-containing minerals according to claim 1, wherein the inoculation amount of the mixed bacteria is 5% -40% of the volume and mass of the chromium-contaminated soil; the time of the reduction reaction is 3-7 days.
  9. 9. The method for restoring chromium-contaminated soil by utilizing microorganisms to cooperate with natural iron-containing minerals according to claim 1, wherein the chromium-reducing bacteria are added to the system in the environment with low oxidation-reduction potential for reducing hexavalent chromium after being subjected to expansion culture in a shaker with the temperature of 25-35 ℃ and the rotation speed of 120-180 rpm for 10-14 days.
  10. 10. The method for restoring chromium-contaminated soil by utilizing microorganisms in combination with natural iron-containing minerals according to claim 1, wherein the inoculation amount of the chromium-reducing bacteria is 5% -30% of the volume mass of the chromium-contaminated soil.

Description

Method for repairing chromium-polluted soil by cooperation of microorganisms and natural iron-containing minerals Technical Field The application belongs to the technical field of chromium-polluted soil restoration, and particularly relates to a method for restoring chromium-polluted soil by cooperation of microorganisms and natural iron-containing minerals. Background Chromium slag discharged in the chromium salt production process easily causes serious pollution to a storage yard and the surrounding environment. The toxicity of chromium is mainly derived from hexavalent chromium, the toxicity of hexavalent chromium is about 100 times higher than that of trivalent chromium, and the chromium has strong oxidability, is easily absorbed by organisms and causes mutation of the organisms, so that the pollution of the chromium to the treated soil is not sustained. At present, researches find that microorganisms have effects of accumulating and detoxifying hexavalent chromium, and the method has the advantages of high efficiency, low cost, small influence on environment and the like in treating chromium pollution, so that the microorganism has been reported in a plurality of researches. However, the problems of insufficient electron donor and poor stability of repair products still commonly exist in the process of repairing hexavalent chromium by microorganisms, so that the repair efficiency is difficult to continuously improve, and the reduced trivalent chromium is easily reoxidized into hexavalent chromium by oxidizing substances in the environment, so that pollution is caused to return yellow and rebound, and the practical application and long-acting stability of the technology are severely restricted. Disclosure of Invention The application aims to provide a method for repairing chromium-polluted soil by utilizing microorganism cooperated with natural iron-containing minerals, which is used for solving the problems of low repairing efficiency and unstable repairing products in the existing chromium-polluted soil repairing method, efficiently providing electron donors by utilizing the natural iron-containing minerals, promoting hexavalent chromium to reduce and mineralize to generate chromite-like products, realizing long-acting stable repairing of the chromium-polluted soil, and avoiding re-dissolution and re-pollution of the repaired chromium-polluted soil. In order to solve the technical problems, the application is realized as follows: In a first aspect, an embodiment of the present application provides a method for repairing chromium-contaminated soil by microorganisms in combination with natural iron-containing minerals, the method comprising: mixing natural iron-containing minerals into chromium-contaminated soil, standing for several days, adding mixed bacteria into the obtained system, standing for reduction reaction, reducing high-valence iron and high-valence sulfur in the system into ferrous iron and ferrous sulfur, and forming a low oxidation-reduction potential environment in the system; adding chromium reducing bacteria into a system in a low oxidation-reduction potential environment, standing and reducing hexavalent chromium to obtain trivalent chromium, and carrying out mineralization reaction on the trivalent chromium and the ferrous iron to obtain a chromite-like product, so as to repair the chromium-polluted soil; wherein the mixed bacteria are formed by compounding sulfate reducing bacteria EM2 and alicyclic acid bacillus. Optionally, the sulfate reducing bacteria EM2 is preserved in China Center for Type Culture Collection (CCTCC) with a preservation number of M2017645; The chromium-reducing bacteria are selected from at least one of microbacterium GRINML SWG, chromium-reducing bacillus GRINML SWG and fens-type fiber microbacterium GRINML SWG; Wherein the microbacterium GRINML SWG1 is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021992; The chromium-reduced bacillus GRINML SWG is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021991; The Fenne type fiber microzyme GRINML SWG is preserved in China Center for Type Culture Collection (CCTCC) with the preservation number of M2021990. Optionally, the method further comprises: And in the step of standing and reducing hexavalent chromium, monitoring the oxidation-reduction potential of a reduction system, and supplementing the mixed bacteria into the reduction system when the oxidation-reduction potential is higher than zero potential so as to recover the oxidation-reduction potential in the reduction system to be lower than zero potential. Optionally, the natural iron-containing mineral is selected from at least one of natural pyrite, natural magnetite, and natural hematite. Optionally, the natural iron-containing mineral has a particle size of 63.5 μm to 254 μm; the addition amount of the natural iron-containing minerals accounts for 0.2% -1% of