Method for cooperatively repairing chromium polluted soil by biochar-based zero valent iron and microorganism

Abstract

The invention discloses a method for cooperatively repairing chromium polluted soil by biochar-based zero valent iron and microorganism, and relates to methods for repairing soil environments. The method for cooperatively repairing the chromium polluted soil by the biochar-based zero valent iron and microorganism aims to solve the problem that agglomeration and oxidation are prone to occurring easily when the chromium polluted soil is repaired. The method for repairing the chromium polluted soil includes the steps that the biochar-based zero valent iron is prepared, specifically, biomass is added to a soluble iron salt solution for modification, the modified biomass is filtred and roasted to obtain a biochar-based zero valent iron remediation material; strain domestication is carried out,specifically, an organic matter and hydrogen are selected from the chromium polluted soil as electron donors, hexavalent chromium, trivalent iron, sulfate, nitrate and oxygen are selected from the chromium polluted soil as dominant bacteria of electron acceptors for metabolism activities to be subjected to domestication and expanding culture; and repairing is carried out, specifically, the biochar-based zero valent iron, the dominant bacteria and the chromium polluted soil to be repaired are mixed at room temperature for repair. According to the method for cooperatively repairing the chromiumpolluted soil by biochar-based zero valent iron and microorganism, the reduction rate of the hexavalent chromium can be greatly improved, the mobility and bioavailability of chromium are reduced, thesoil can further be improved and the microbial diversity can be increased.

Description

technical field

[0001] The invention relates to a soil environment restoration method, in particular to a method for biochar-based zero-valent iron and microorganisms to synergistically restore chromium-contaminated soil. Background technique

[0002] As one of the important chemical raw materials, chromium is widely used in metallurgy, electroplating, tanning, printing and dyeing and other industries. Due to leakage in the production process, non-standard discharge of wastewater, and infiltration of chromium-containing waste residues, a large amount of chromium entered the surrounding soil and groundwater of the site. In the soil environment, the main forms of chromium are trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). Trivalent chromium is easily fixed in soil by soil colloids and minerals through adsorption, coordination, complexation, precipitation, etc., and its mobility and bioavailability are low. Because hexavalent chromium is negatively charged, it...

Examples

Embodiment 1

[0037] Add 0.6g of biomass to 100mL ferric chloride solution with a concentration of 0.5mol / L, stir at 60rpm for 8h to make it evenly mixed, then add ammonia water with a concentration of 10%, adjust the pH of the solution to 5-7, filter The biomass was washed several times with deionized water, dried at 80°C, and then roasted at 600°C for 8 hours under anaerobic conditions to obtain the biochar-based zero-valent iron restoration material BC-Fe 0 (FeCl 3 ).

[0038] Add 0.6g of biomass to 100mL ferric nitrate solution with a concentration of 0.5mol / L, stir at 60rpm for 8h to make it evenly mixed, then add ammonia water with a concentration of 10%, adjust the pH of the solution to 5-7, The biomass was filtered and washed several times with deionized water, dried at 80°C and then roasted at 600°C for 8 hours under anaerobic conditions to obtain the biochar-based zero-valent iron restoration material BC-Fe 0 (Fe(NO 3 ) 3 ).

[0039] Add 0.6g of biomass to 100mL ferric citrate ...

Embodiment 2

[0046] Biochar-based zero-valent iron (BC-Fe 0 (FeCl 3 )) and bacterial suspension preparation method are the same as in Example 1. Weigh 10g of chromium-contaminated soil with a concentration of 200mg / kg and transfer it to a 50mL centrifuge tube. The original soil pH value is 6.2, adjust the soil moisture content to 60% with water, and add zero-valent iron or biochar at a concentration of 0.25g / kg. Based on zero-valent iron and a bacterial suspension with a concentration of 80 mg / kg, mix them evenly, cover and seal them, and culture them statically at room temperature 20°C, 25°C and 30°C for 14 days. After the reaction, add quantitative deionized water and centrifuge at 4000rpm for 10 minutes to measure the chromium concentration in the supernatant; measure the change of chromium occurrence form in the remediation soil by multi-step continuous extraction method.

[0047] Four reaction systems were set up in the remediation process: 1. Blank system, including blank or chromi...

Embodiment 3

[0060] Biochar-based zero-valent iron (BC-Fe 0 (FeCl 3 )) and bacterial suspension preparation method are the same as in Example 1. Weigh 10g of chromium-contaminated soil with a concentration of 200mg / kg and transfer it to a 50mL centrifuge tube. kg of biochar-based zero-valent iron and bacterial suspension with a concentration of 80 mg / kg, mix well, cover and seal, and culture at room temperature 30°C for 14 days. After the reaction, add quantitative deionized water and centrifuge at 4000 rpm for 10 minutes to measure the chromium concentration in the supernatant. It can be seen from Table 6 that when the dosage of biochar-based zero-valent iron increases from 0.05 to 1g / kg, the removal ability of soil water-soluble hexavalent chromium after 14 days of reaction increases from 23mg Cr / g Fe 0 Rise to 53mgCr / g Fe 0 , the removal capacity of total chromium from 34mg Total Cr / g Fe 0 Rise to 79mg Total Cr / g Fe 0 , but when the amount of biochar-based zero-valent iron exceeds...

technical field

[0001] The invention relates to a soil environment restoration method, in particular to a method for biochar-based zero-valent iron and microorganisms to synergistically restore chromium-contaminated soil. Background technique

[0002] As one of the important chemical raw materials, chromium is widely used in metallurgy, electroplating, tanning, printing and dyeing and other industries. Due to leakage in the production process, non-standard discharge of wastewater, and infiltration of chromium-containing waste residues, a large amount of chromium entered the surrounding soil and groundwater of the site. In the soil environment, the main forms of chromium are trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). Trivalent chromium is easily fixed in soil by soil colloids and minerals through adsorption, coordination, complexation, precipitation, etc., and its mobility and bioavailability are low. Because hexavalent chromium is negatively charged, it...

Examples

Embodiment 1

[0037] Add 0.6g of biomass to 100mL ferric chloride solution with a concentration of 0.5mol / L, stir at 60rpm for 8h to make it evenly mixed, then add ammonia water with a concentration of 10%, adjust the pH of the solution to 5-7, filter The biomass was washed several times with deionized water, dried at 80°C, and then roasted at 600°C for 8 hours under anaerobic conditions to obtain the biochar-based zero-valent iron restoration material BC-Fe 0 (FeCl 3 ).

[0038] Add 0.6g of biomass to 100mL ferric nitrate solution with a concentration of 0.5mol / L, stir at 60rpm for 8h to make it evenly mixed, then add ammonia water with a concentration of 10%, adjust the pH of the solution to 5-7, The biomass was filtered and washed several times with deionized water, dried at 80°C and then roasted at 600°C for 8 hours under anaerobic conditions to obtain the biochar-based zero-valent iron restoration material BC-Fe 0 (Fe(NO 3 ) 3 ).

[0039] Add 0.6g of biomass to 100mL ferric citrate ...

Embodiment 2

[0046] Biochar-based zero-valent iron (BC-Fe 0 (FeCl 3 )) and bacterial suspension preparation method are the same as in Example 1. Weigh 10g of chromium-contaminated soil with a concentration of 200mg / kg and transfer it to a 50mL centrifuge tube. The original soil pH value is 6.2, adjust the soil moisture content to 60% with water, and add zero-valent iron or biochar at a concentration of 0.25g / kg. Based on zero-valent iron and a bacterial suspension with a concentration of 80 mg / kg, mix them evenly, cover and seal them, and culture them statically at room temperature 20°C, 25°C and 30°C for 14 days. After the reaction, add quantitative deionized water and centrifuge at 4000rpm for 10 minutes to measure the chromium concentration in the supernatant; measure the change of chromium occurrence form in the remediation soil by multi-step continuous extraction method.

[0047] Four reaction systems were set up in the remediation process: 1. Blank system, including blank or chromi...

Embodiment 3

[0060] Biochar-based zero-valent iron (BC-Fe 0 (FeCl 3 )) and bacterial suspension preparation method are the same as in Example 1. Weigh 10g of chromium-contaminated soil with a concentration of 200mg / kg and transfer it to a 50mL centrifuge tube. kg of biochar-based zero-valent iron and bacterial suspension with a concentration of 80 mg / kg, mix well, cover and seal, and culture at room temperature 30°C for 14 days. After the reaction, add quantitative deionized water and centrifuge at 4000 rpm for 10 minutes to measure the chromium concentration in the supernatant. It can be seen from Table 6 that when the dosage of biochar-based zero-valent iron increases from 0.05 to 1g / kg, the removal ability of soil water-soluble hexavalent chromium after 14 days of reaction increases from 23mg Cr / g Fe 0 Rise to 53mgCr / g Fe 0 , the removal capacity of total chromium from 34mg Total Cr / g Fe 0 Rise to 79mg Total Cr / g Fe 0 , but when the amount of biochar-based zero-valent iron exceeds...

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