阅读说明：本技术 一种利用负载芽孢杆菌的电石渣活化过硫酸钠修复有机污染土的方法 (Method for repairing organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus ) 是由 魏明俐 薛强 刘磊 陈亿军 万勇 李江山 李源 于 2021-09-14 设计创作，主要内容包括：本发明涉及一种利用负载芽孢杆菌的电石渣活化过硫酸钠修复有机污染土的方法,首先对有机污染土壤进行预处理,测试有机污染土壤的含水率,计算干土质量,测试有机污染物的浓度；接着采用芽孢杆菌发酵菌液制备负载芽孢杆菌的电石渣；往有机污染土壤中加入过硫酸钠和负载芽孢杆菌的电石渣,过硫酸钠与有机污染土壤中有机污染物的摩尔比为10～50：1,加水控制有机污染土壤中的含水率,然后拌合反应,得到修复后的土壤。本发明采用负载芽孢杆菌的电石渣来活化过硫酸钠,以废治废,绿色环保,能实现对老化高浓度有机污染土,特别是苯系物、多环芳烃有机污染土的快速修复,同时芽孢杆菌不仅可以增强修复过程还可以降低土壤的盐碱性,减少二次污染。(The invention relates to a method for restoring organic contaminated soil by activating sodium persulfate through carbide slag loaded with bacillus, which comprises the steps of pretreating the organic contaminated soil, testing the water content of the organic contaminated soil, calculating the quality of dry soil and testing the concentration of organic pollutants; then preparing carbide slag loaded with bacillus by using bacillus fermentation bacteria liquid; adding sodium persulfate and the carbide slag loaded with bacillus into the organic contaminated soil, wherein the molar ratio of the sodium persulfate to the organic contaminants in the organic contaminated soil is 10-50: adding water to control the water content in the organic contaminated soil, and then mixing for reaction to obtain the repaired soil. According to the invention, the calcium carbide slag loaded with the bacillus is adopted to activate the sodium persulfate, so that the waste is treated by the waste, the method is green and environment-friendly, the rapid repair of aged high-concentration organic polluted soil, especially benzene series and polycyclic aromatic hydrocarbon organic polluted soil can be realized, and meanwhile, the bacillus can enhance the repair process, reduce the salt alkalinity of the soil and reduce the secondary pollution.)

1. A method for restoring organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus is characterized by comprising the following steps:

(1) pretreating the organic contaminated soil, testing the water content of the organic contaminated soil, calculating the dry soil quality, and testing the concentration of organic pollutants in the organic contaminated soil;

(2) preparing a bacillus zymocyte liquid, and then preparing carbide slag loaded with bacillus by using a hot solution chemical deposition method;

(3) adding sodium persulfate and the carbide slag loaded with bacillus into the organic contaminated soil, wherein the molar ratio of the addition amount of the sodium persulfate to the organic pollutants in the organic contaminated soil is 10-50: and 1, then carrying out blending reaction to obtain the repaired soil.

2. The method for remediating organically-polluted soil by activating sodium persulfate through the bacillus-loaded carbide slag as set forth in claim 1, wherein in the step (1), the pretreatment is: removing large broken stones in the organic contaminated soil, and then crushing and uniformly mixing the organic contaminated soil.

3. The method for remediating organic contaminated soil by activating sodium persulfate through the bacillus-loaded carbide slag as claimed in claim 1, wherein in the step (2), the method for preparing the bacillus zymophyte liquid comprises:

1) inoculating a bacillus strain which is frozen and stored at the temperature of-90 ℃ into a plate culture medium for activation culture, wherein the activation conditions are as follows: activating for 12h at the temperature of 38 +/-2 ℃ in a dark place;

2) the monoclonal colonies growing in the plate medium were selected using an inoculating loop and inoculated in a medium containing 500mL of sterile seed solution, the medium formulation being: 10g of peptone, 5g of yeast extract and 10g of sodium chloride, wherein the pH value is 7.2, and the mixture is placed in a horizontal shaking table with 200rpm and the temperature of 38 +/-2 ℃ for shaking culture for 10 hours to obtain the bacillus zymophyte liquid.

4. The method for remediating organically-polluted soil using bacillus-loaded acetylene sludge for activating sodium persulfate according to claim 1, wherein in the step (2), the method for preparing the bacillus-loaded acetylene sludge mixture comprises:

1) completely drying the carbide slag, grinding, sieving with a 75 μm sieve, and taking the carbide slag under the sieve for later use;

2) centrifuging bacillus fermentation bacteria liquid at the room temperature at the speed of 5000r/min for 20min, adding the centrifugal thalli precipitate into a galactose protective agent at the mass ratio of 1:1, carrying out vacuum freeze drying under the aseptic condition to obtain solid fermentation bacillus, and sieving the solid fermentation bacillus through a 75-micrometer sieve after crushing;

3) mixing solid-state fermentation bacillus and carbide slag according to the mass ratio of (5-10) to (90-95), and adding the mixture into sterile ultrapure deionized water, wherein the solid-liquid ratio is 1: 20g/mL, oscillating in a horizontal shaker at the room temperature at the rotating speed of 200rpm for 12h, and then drying to constant weight to obtain the carbide slag loaded with the bacillus.

5. The method for remediating organically-polluted soil by activating sodium persulfate through the bacillus-loaded carbide slag as claimed in claim 1, wherein in the step (3), the mass ratio of the bacillus-loaded carbide slag to the sodium persulfate is 1: 3.

6. The method for remediating organically-polluted soil using Bacillus-charged carbide slag to activate sodium persulfate according to claim 1, wherein the temperature of the blending reaction in the step (3) is 23 ± 1 ℃.

7. The method for remediating organically-polluted soil using Bacillus-charged carbide slag to activate sodium persulfate as described in any one of claims 1 to 6, wherein in the step (3), water is added to the organically-polluted soil to a water content of 30 to 35% before the blending reaction.

Technical Field

The invention belongs to the technical field of environmental rock and soil, and particularly relates to a method for repairing organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus.

Background

The types of organic pollutants have complex spatial distribution, the main pollutants in the northeast of China are polycyclic aromatic hydrocarbons, the main pollutants in the northeast and middle China are benzenes and organochlorine pesticides, the main pollutants in the east and south China are polychlorinated biphenyls, and the complex compound organic pollutants exist in the areas with dense population and high industrialization degree. Therefore, a green and efficient repair technique must be developed.

The prior art widely applies chemical oxidation repair technology, and the chemical oxidation repair technology is as follows: hydrogen peroxide oxidation, potassium permanganate oxidation, and persulfate oxidation. The hydrogen peroxide oxidation method can generate more free radicals to oxidize organic matters, but in the underground soil environment, the free radicals are quickly reacted after being generated, and the durability is poor, so that the method is not beneficial to the treatment of organic pollutants in the soil; the potassium permanganate is adopted to oxidize the organic matters, so that the types of the organic matters which can be effectively treated are not wide enough, and the applicability is poor; the persulfate (sodium persulfate is commonly used) is used for avoiding the two main problems, the persulfate is suitable for treating the high-concentration organic polluted soil, the sodium persulfate is independently added for repairing the organic polluted soil, the effect is poor, the repairing period is long, and some activation technologies are required to be adopted for greatly improving the oxidation efficiency.

Conventionally, there is a method of activating with a strong base such as sodium hydroxide, and for example, (Zhao, Liao et al.2013) about 70% of contaminants can be oxidized in 72 hours by adding 7.5ml of a 0.5mol/l sodium persulfate solution to 5g of a soil contaminated with polycyclic aromatic hydrocarbon and adjusting the pH to 12 with sodium hydroxide. The repair efficiency of sodium persulfate activated by sodium hydroxide is still low, and the following disadvantages are mainly existed: 1. the cost is increased by using a large amount of strong alkali such as sodium hydroxide; 2. strong alkali such as sodium hydroxide is used, so that the low-carbon green soil remediation principle is not met, and the carbon footprint in the remediation process is increased; 3. the use of strong alkali such as sodium hydroxide can cause salinization of soil, which is not beneficial to secondary utilization of soil.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for repairing organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus. Compared with the method of activating by using sodium hydroxide, the method has the advantages of high restoration efficiency, low cost, waste utilization, simple and safe construction, strong alkaline durability of the adopted carbide slag, capability of generating calcium sulfate and convenience for resource utilization of the restored polluted soil.

The invention adopts the carbide slag loaded with bacillus to activate sodium persulfate as a repairing agent of organic polluted soil, the carbide slag can provide enough alkalinity to activate the sodium persulfate, and the principle is as follows:

SO₄ ^·-+OH^-→SO₄ ^2-+OH^· (2)

under the alkaline environment, the decomposition of sodium persulfate is promoted to generate sulfate radicals and superoxide radicals, and then the sulfate radicals and hydroxyl radicals can be generated through the reaction of the hydroxyl radicals. After alkali activation, a large amount of stable superoxide radicals, hydroxyl radicals and sulfate radicals can be generated, organic matters are quickly oxidized, and the method has a good effect on most organic matters. The bacillus also has certain oxidizability, and can also oxidize organic pollutants, and meanwhile, the bacillus can relieve the salt alkalinity of soil.

Technical scheme

A method for restoring organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus comprises the following steps:

(1) pretreating the organic contaminated soil, testing the water content of the organic contaminated soil, calculating the dry soil quality, and testing the concentration of organic pollutants in the organic contaminated soil;

(2) preparing a bacillus zymocyte liquid, and then preparing carbide slag loaded with bacillus by using a hot solution chemical deposition method;

(3) adding sodium persulfate and the carbide slag loaded with bacillus into the organic contaminated soil, wherein the molar ratio of the addition amount of the sodium persulfate to the organic pollutants in the organic contaminated soil is 10-50: and 1, then carrying out blending reaction to obtain the repaired soil.

Further, in the step (1), the pretreatment is: removing large broken stones in the organic polluted soil, and then crushing and uniformly mixing the organic polluted soil.

Further, in the step (2), the method for preparing the bacillus zymocyte liquid comprises the following steps:

1) inoculating a bacillus strain which is frozen and stored at the temperature of-90 ℃ into a plate culture medium for activation culture, wherein the activation conditions are as follows: activating for 12h at the temperature of 38 +/-2 ℃ in a dark place;

2) the monoclonal colony growing in the plate culture medium is selected by using an inoculating loop and inoculated in a culture medium filled with 500mL of a sterilized seed solution, and the formula of the culture medium is as follows: 10g of peptone, 5g of yeast extract and 10g of sodium chloride, wherein the pH value is 7.2, and the mixture is placed in a horizontal shaking table with 200rpm and the temperature of 38 +/-2 ℃ for shaking culture for 10 hours to obtain the bacillus zymophyte liquid.

Further, in the step (2), the method for preparing the carbide slag mixture loaded with the bacillus comprises the following steps:

1) completely drying the carbide slag, grinding, sieving with a 75 μm sieve, and taking the carbide slag under the sieve for later use;

2) centrifuging the bacillus fermentation bacteria liquid at the speed of 5000r/min for 20min at room temperature, adding the centrifugal thalli precipitate into a galactose protective agent in a mass ratio of 1:1, carrying out vacuum freeze drying under the aseptic condition to obtain solid fermentation bacillus, and sieving by a 75-micrometer sieve after crushing;

3) mixing solid-state fermentation bacillus and carbide slag according to the mass ratio of (5-10) to (90-95), and adding the mixture into sterile ultrapure deionized water, wherein the solid-liquid ratio is 1: 20g/mL, oscillating in a horizontal shaker at the room temperature at the rotating speed of 200rpm for 12h, and then drying to constant weight to obtain the carbide slag loaded with the bacillus.

In the prepared carbide slag loaded with the bacillus, the number of live spores of the bacillus in each gram of the carbide slag loaded with the bacillus is 1 multiplied by 10¹⁰–2×10¹⁰The number of the best load viable bacteria is 1.5 multiplied by 10¹⁰。

Further, in the step (3), the mass ratio of the carbide slag loaded with the bacillus to the sodium persulfate is 1: 3.

Further, in the step (3), the temperature of the kneading reaction is 23. + -. 1 ℃.

Further, in the step (3), before the blending reaction, water is added to ensure that the water content in the organic contaminated soil is 30-35%.

The invention has the beneficial effects that: the invention provides a method for repairing organic polluted soil by using sodium persulfate activated by carbide slag loaded with bacillus, the method adopts the carbide slag loaded with the bacillus to activate the sodium persulfate, treats waste by waste, is green and environment-friendly, can realize efficient and low-carbon footprint repair of aged high-concentration organic polluted soil, particularly benzene series, polycyclic aromatic hydrocarbon, petroleum hydrocarbon and the like, and provides a better solution for repairing the aged high-concentration organic polluted soil which is difficult to treat.

Drawings

FIG. 1 is a flowchart showing a method for remediating organically-polluted soil using sodium persulfate activated with acetylene sludge in example 1;

FIG. 2 is a graph showing the remediation efficiency of toluene-contaminated soil using the methods of example 1, comparative example 1, and comparative example 2;

FIG. 3 is a graph showing the pH of soil after remediation of toluene-contaminated soil using the methods of example 1, comparative example 1, and comparative example 2;

FIG. 4 is a graph showing the remediation efficiency of naphthalene contaminated soil using the methods of example 2, comparative example 3, and comparative example 4;

FIG. 5 is a graph showing the pH of the soil after remediation of naphthalene contaminated soil using the methods of example 2, comparative example 3, and comparative example 4.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings and specific embodiments, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1: repairing aged high-concentration volatile organic pollutants represented by toluene

A method for repairing organic polluted soil by activating sodium persulfate through carbide slag loaded with bacillus is shown as a flow chart in figure 1:

preparing organic matter contaminated soil: sorting the soil to be polluted, screening out large gravels, crushing, wherein the related physical and chemical indexes of the soil to be polluted are detailed in a table 1; and adding a pollutant toluene into the soil to be polluted to enable the concentration of the pollutant toluene to be 2400mg/kg, and obtaining the soil polluted by the toluene. The method is adopted to repair the artificial wetland.

TABLE 1 main physicochemical indices of unpolluted soil for the tests

The repairing method comprises the following steps:

(1) after the toluene-polluted soil is crushed and uniformly mixed, testing the water content of the polluted soil, and calculating the dry soil mass, wherein the toluene pollution concentration is 2400 mg/kg;

(2) preparing a bacillus zymocyte liquid, and then preparing carbide slag loaded with bacillus by using a hot solution chemical deposition method;

the preparation method of the bacillus zymocyte liquid comprises the following steps:

1) inoculating a bacillus strain which is frozen and stored at the temperature of-90 ℃ into a plate culture medium for activation culture, wherein the activation conditions are as follows: activating for 12h at the temperature of 38 +/-2 ℃ in a dark place;

2) the monoclonal colony growing in the plate culture medium is selected by using an inoculating loop and inoculated in a culture medium filled with 500mL of a sterilized seed solution, and the formula of the culture medium is as follows: 10g of peptone, 5g of yeast extract and 10g of sodium chloride, the pH value is 7.2, and the mixture is placed in a horizontal shaking table at 200rpm and the temperature of 38 +/-2 ℃ for shaking culture for 10 hours (16 layers of sterilized gauze are used for sealing to ensure the dissolved oxygen amount).

The method for preparing the carbide slag loaded with the bacillus comprises the following steps:

1) completely drying the carbide slag, grinding, sieving with a 75 μm sieve, and taking the carbide slag under the sieve for later use;

2) centrifuging bacillus fermentation bacteria liquid at room temperature at 5000r/min for 20min, adding thallus centrifugal precipitate into galactose protective agent at mass ratio of 1:1, vacuum freeze drying under aseptic condition (80 deg.C, 12 hr) to obtain solid fermentation bacillus, pulverizing, and sieving with 75 μm sieve;

3) mixing solid-state fermentation bacillus and carbide slag according to the mass ratio of 10:90, and adding the mixture into sterile ultrapure deionized water, wherein the solid-liquid ratio is 1: 20g/mL, oscillating in a horizontal shaker at the room temperature at the rotating speed of 200rpm for 12h, and then drying at 120 ℃ to constant weight to obtain the carbide slag loaded with the bacillus.

(3) Adding sodium persulfate and the carbide slag loaded with bacillus into the soil polluted by the toluene, wherein the molar ratio of the addition amount of the sodium persulfate to the toluene in the soil polluted by the toluene is 10: 1 (the addition amount of sodium persulfate is 62g/kg), the addition amount of the carbide slag loaded with bacillus is 21g/kg, then water is added to control the water content in the organic polluted soil to be about liquid limit (the water content is 35% in the embodiment), then stirring reaction is carried out at 23 ℃, the pollutant concentration is monitored when the water content is 0h, 7h, 14h, 1d, 3d, 7d, 14d, 28d, 56d and 90d, the remediation efficiency is observed, and the remediated soil is obtained after remediation is completed.

Comparative example 1

The contaminated soil was the same as in example 1.

The remediation of contaminated soil was carried out by using only 62g/kg of sodium persulfate without using the carbide slag loaded with Bacillus, and the rest was the same as in example 1.

Comparative example 2

The contaminated soil was the same as in example 1.

The polluted soil is repaired by adopting sodium hydroxide and sodium persulfate without adopting the carbide slag loaded with bacillus, wherein the addition amount of the sodium persulfate is 62g/kg, the addition amount of the sodium hydroxide is 21g/kg, and the rest is consistent with that of the example 1.

The repair efficiency curves of the methods of example 1, comparative example 1 and comparative example 2 for repairing the toluene-contaminated soil are shown in fig. 2, and it can be seen that the repair efficiency curves of example 1 and comparative example 2 both show the same rule, i.e., the organic matter is rapidly oxidized at the early stage (the first stage process), and then is steadily increased for a period of time (the second stage process) until the repair requirements are met. Meanwhile, it can be seen that the repair efficiency can be obviously improved by activating sodium persulfate through the carbide slag loaded with the bacillus, the repair rate of 98.97% can be achieved in the third day of repair, and the repair rate of 99.88% can be achieved only after about 56 days in comparative example 1.

FIG. 2 is the pH value of the soil after the toluene contaminated soil is repaired by the methods of example 1, comparative example 1 and comparative example 2, and it can be seen that the pH value in the comparative example is obviously increased to be over 10, particularly the pH value in the comparative example 2 added with sodium hydroxide reaches over 12, and the secondary resource utilization of the soil is very not facilitated due to the excessively high saline-alkali property; and in the embodiment 1, the pH value is greatly reduced to about 9, and the salt alkalinity of the soil is relieved.

Example 2: remediation of organic pollutants of low volatility, represented by naphthalene, which is a representative substance in polycyclic aromatic hydrocarbons

Preparing organic matter contaminated soil: the soil to be contaminated (same as example 1) was sorted, the large sand was sieved off, crushed, and the contaminant naphthalene was added to the soil to be contaminated to a concentration of 1400mg/kg, to obtain naphthalene-contaminated soil. The method is adopted to repair the artificial wetland.

The repairing method comprises the following steps:

(1) after the soil polluted by naphthalene is crushed and uniformly mixed, testing the water content of the polluted soil, and calculating the dry soil mass, wherein the naphthalene pollution concentration is 1400 mg/kg;

(2) preparing a bacillus zymocyte liquid, and then preparing carbide slag loaded with bacillus by using a hot solution chemical deposition method;

the preparation method of the bacillus zymocyte liquid comprises the following steps:

1) inoculating a bacillus strain which is frozen and stored at the temperature of-90 ℃ into a plate culture medium for activation culture, wherein the activation conditions are as follows: activating for 12h at the temperature of 38 +/-2 ℃ in a dark place;

2) the monoclonal colony growing in the plate culture medium is selected by using an inoculating loop and inoculated in a culture medium filled with 500mL of a sterilized seed solution, and the formula of the culture medium is as follows: 10g of peptone, 5g of yeast extract and 10g of sodium chloride, the pH value is 7.2, and the mixture is placed in a horizontal shaking table at 200rpm and the temperature of 38 +/-2 ℃ for shaking culture for 10 hours (16 layers of sterilized gauze are used for sealing to ensure the dissolved oxygen amount).

The method for preparing the carbide slag loaded with the bacillus comprises the following steps:

1) completely drying the carbide slag, grinding, sieving with a 75 μm sieve, and taking the carbide slag under the sieve for later use;

2) centrifuging the bacillus fermentation bacteria liquid at the speed of 5000r/min for 20min at room temperature, adding the centrifugal thalli precipitate into a galactose protective agent in a mass ratio of 1:1, carrying out vacuum freeze drying under the aseptic condition to obtain solid fermentation bacillus, and sieving by a 75-micrometer sieve after crushing;

3) mixing the solid-state fermentation bacillus and the carbide slag according to the mass ratio of 5:95, and adding the mixture into sterile ultrapure deionized water, wherein the solid-liquid ratio is 1: 20g/mL, oscillating in a horizontal shaker at the room temperature at the rotating speed of 200rpm for 12h, and then drying to constant weight to obtain the carbide slag loaded with the bacillus.

(3) Adding sodium persulfate and the carbide slag loaded with bacillus into the soil polluted by naphthalene, wherein the molar ratio of the addition amount of the sodium persulfate to toluene in the soil polluted by toluene is 30: 1 (the addition amount of sodium persulfate is 78g/kg), the addition amount of the carbide slag loaded with the bacillus is 26g/kg, then water is added to control the water content in the organic contaminated soil to be about the liquid limit (the water content is 35% in the embodiment), then stirring reaction is carried out at 23 ℃, the pollutant concentrations in 0h, 7h, 14h, 1d, 3d, 7d, 14d, 28d, 56d and 90d are monitored, the remediation efficiency is observed, and the remediated soil is obtained after remediation is completed.

Comparative example 3

The contaminated soil was the same as in example 2.

The remediation of contaminated soil was carried out without using the carbide slag loaded with Bacillus, but with 78g/kg of sodium persulfate, the remainder being identical to that of example 2.

Comparative example 4

The contaminated soil was the same as in example 2.

The polluted soil is repaired by adopting sodium hydroxide and sodium persulfate without adopting the carbide slag loaded with bacillus, wherein the addition amount of the sodium persulfate is 78g/kg, the addition amount of the sodium hydroxide is 26g/kg, and the rest is consistent with that of the example 1.

The restoration efficiency curves of the methods of example 2, comparative example 3 and comparative example 4 for restoring the naphthalene-contaminated soil are shown in fig. 4, and it can be seen that the restoration efficiency curves of example 2 and comparative example 4 both show the same rule, i.e. the organic matter is rapidly oxidized in the early stage (first stage process), and then is steadily increased for a period of time (second stage process) until the restoration requirement is met, but the restoration efficiency of the naphthalene-contaminated soil is lower than that of the toluene-contaminated soil. The repairing efficiency can be obviously improved by activating sodium persulfate by using the carbide slag loaded with the bacillus, the repairing of naphthalene polluted soil is completed at 28 days, the repairing rate reaches 99.11 percent, and when the carbide slag loaded with the bacillus is not used for activation (comparative example 4), the repairing efficiency after 90 days of reaction is only 74.59 percent, and the repairing rate in the comparative example 3 is negligible (only 6.11 percent when 90 days are adopted).

Fig. 5 is a graph showing the pH of the soil after the naphthalene-contaminated soil is remediated by the methods of example 2, comparative example 3 and comparative example 4, and it can be seen that, similarly, example 2 greatly lowers the pH to about 9, which effectively relieves the salt alkalinity of the soil.

In conclusion, the alkaline environment provided by the carbide slag loaded with the bacillus can effectively activate the sodium persulfate, so that the sodium persulfate can be better applied to repairing aged high-concentration organic polluted soil, the salinization of the soil can be effectively relieved, the soil can have the potential of secondary utilization, the purposes of treating wastes with wastes and realizing high efficiency and low carbon footprint can be achieved, and the advanced oxidation technology of the carbide slag loaded with the bacillus as a green repairing means in the foreseeable future has wide application value in the field of repairing the organic polluted soil.

The following embodiments are provided for the purpose of illustrating the present invention and are not to be construed as limiting the present invention in any way, and it will be apparent to those skilled in the art that the technical features of the present invention can be modified or changed in some ways without departing from the scope of the present invention.