TW201703834A - Treatment method of dioxin-containing soils - Google Patents

Abstract

A treatment method of dioxin-containing soils is provided. The treatment method has steps of: (1) providing an emulsion solution; (2) mixing the emulsion solution with dioxin-containing soils, so that a first part of dioxin is released from the dioxin-containing soils into the emulsion solution; (3) filtering out the emulsion solution containing the first part of dioxin to obtain the dioxin-containing soils; (4) adding a microorganism for decomposing dioxins into the dioxin-containing soils; and (5) allowing the dioxin-containing soils to stand for performing a biodegradation, so that a second part of dioxin is removed from the dioxin-containing soils.

Description

Remediation method containing Dioxin soil

The invention relates to a method for remediation of soil containing dioxin, in particular to a method for remediation combined with leaching and biodegradation of dioxin.

Dioxin compounds are attributed to persistent organic pollutants (POPs), which are toxic to humans, including dermal toxicity, neurotoxicity, hepatotoxicity, carcinogenic toxicity, reproductive system toxicity, etc.; Dioxin is also a powerful cancer-promoting agent. , has been classified as "a first-class human to determine carcinogens." In addition, Dioxin has a long half-life, stable chemical and physical properties, and is bioaccumulative, easily accumulating in the food chain, thereby jeopardizing the top human beings in the food chain. The chemical structure of these compounds is similar to that of human hormones, so they can bind to hormone receptors, causing the body to exert excessive effects on hormones in the body; or directly stimulate or inhibit the endocrine system, interfere with the body's hormone balance, and make the endocrine system dysfunctional. In order to protect the health of the human body, it is necessary to rectify the treatment with dioxin.

Dioxin can be discharged into the general environment from different sources by different release methods, and spread by different natural effects such as volatilization, long-distance transmission, dry/wet sedimentation, photolysis, bioaccumulation and amplification, and biodegradation. Environmental media or organisms, where dry/wet sedimentation is the primary mechanism by which dioxin is brought to surface waters or soil.

In the case of Dioxin in the soil, volatilization and photolysis only occur in the top layer of the soil. It is not easily decomposed by microorganisms. In addition, Dioxin is extremely difficult to dissolve in water, and it is not easy to migrate vertically with the infiltration of water. Therefore, Dioxin mostly stays within 15 cm of the surface of the soil. The half-life of Dioxin in the near-surface soil is about 9 to 15 years, and may be as high as 25 to 100 years below the surface. Only a very small amount of dioxin in the soil will volatilize back to the atmosphere, while some soil particles attached to the surface may be transmitted to other places by wind or surface runoff.

The amount of organic matter in the soil also evokes its ability to adsorb dioxin. Dioxin is a hydrophobic organic compound (HOCs), and the higher the hydrophobicity, the more the amount of pollutants adsorbed by natural organic matter (NOM). In addition, the fine particles of less than 62 micrometers (μm) in the soil, that is, the granules and the clay, also contain more dioxin.

At present, there are many techniques for remediation of Dioxin pollution, which can be divided into Methods such as science, chemistry or biology. The physical treatment method refers to the technology of separating pollutants from the contaminated medium, but this method only separates the pollutants from the contaminated medium, and no degradation reaction occurs; therefore, the separated pollutants must be treated subsequently. If the pollutants separated by UV degradation or activated carbon adsorption are used, the treated soil must also be disposed of properly. The chemical treatment method mainly uses soil reductive dehalogenation techniques and chemical oxidation methods to remediate the soil. The chemical reaction procedure can be used to replace the chlorine atoms in the pollutants or convert them into water, carbon dioxide, etc. A hazardous or non-hazardous substance. The biological treatment method can use plants and microorganisms for remediation, the cost is cheaper than physical and chemical treatment, energy consumption and chemical saving, and the ecological damage to the local site is small, and the efficiency and sustainability can be simultaneously considered, but the disadvantage is remediation. The time is usually longer.

At present, the treatment of dioxin-contaminated soil is mostly treated by physical high temperature heat treatment. The method is mainly based on the fact that although the removal rate can reach 99.9% or more, the treatment temperature needs to reach 1000 ° C, which consumes a lot of energy. In addition, special equipment capable of providing high temperatures is required, so the cost of energy and equipment is quite expensive.

Therefore, it is necessary to provide a treatment method containing Dioxin soil, which can reduce the cost of remediation and shorten the remediation time to solve the problems existing in the conventional technology.

The main object of the present invention is to provide a method for remediation of soil containing Dioxin. In the first stage, the emulsified solution is used to extract and remove most of the dioxin in the contaminated soil, and then the second stage is further to remove the contaminated soil by biodegradation. A small part of the residual Dioxin. Since the emulsified solution can be used not only as an extract, but also directly as a nutrient source liquid for microorganisms during biodegradation of dioxin, the soil remediation step can be simplified, the remediation time can be shortened, expensive equipment is not required, and the cost of remediation is reduced, and Reduce the dioxin residue rate to less than 17%.

In order to achieve the above object, an embodiment of the present invention provides a method for treating soil containing Dioxin, which comprises the following steps: (1) providing an emulsification solution comprising vegetable oil, biodegradable surfactant, soybean lecithin And water; (2) mixing the emulsified solution and a dioxin-containing soil to release a first portion of the dioxin from the dioxin-containing soil to the emulsified solution; (3) filtering out the first portion of the dioxin Emulsifying the solution and leaving the soil containing dioxin; (4) adding a microorganism decomposing dioxin to the soil containing dioxin; and (5) allowing the soil containing dioxin to be subjected to biodegradation reaction from the dioxin-containing A second part of the dioxin is removed from the soil.

In an embodiment of the invention, the ratio of vegetable oil to water of the emulsified solution It is from 3:100 to 3:400.

In one embodiment of the present invention, the vegetable oil is from 0.7% to 3% by weight of the emulsified solution, and the biodegradable surfactant is from 0.1% to 0.4% by weight of the emulsified solution, and The soybean lecithin is from 0.01% to 0.02% by weight of the emulsified solution.

In an embodiment of the invention, the emulsified solution further comprises a multivitamin composition, a lactate or a mixture thereof.

In one embodiment of the invention, the multivitamin composition comprises from 0.01% to 0.02% by weight of the emulsified solution, and the lactate comprises from 0.01% to 0.02% by weight of the emulsified solution.

In an embodiment of the invention, the vegetable oil is soybean oil.

In an embodiment of the present invention, in the step (2), an amount of the emulsified solution is 5 to 30 times the volume of the dioxin-containing soil (Pore Volumn, PV for short).

In an embodiment of the present invention, in the step (4), the microorganism capable of decomposing dioxin is Pseudomonas mendocina NSYSU.

In an embodiment of the present invention, in the step (5), the water content of the dioxin-containing soil is 70%.

In an embodiment of the present invention, after the step (5), the method further comprises a step (6): periodically detecting the concentration of the dioxin in the soil containing the dioxin to confirm the remediation effect.

Fig. 1 is a graph showing changes in OCDD and OCDF residual ratio in soil after emulsification solution A rinsing according to an embodiment of the present invention.

Fig. 2 is a graph showing changes in the content of organic carbon in the soil after emulsification solution A rinsing according to an embodiment of the present invention.

The above and other objects, features, and advantages of the present invention will become more apparent from

An embodiment of the present invention provides a method for treating soil containing dioxin, which mainly comprises the steps of: (1) providing an emulsified solution; (2) mixing the emulsified solution and a soil containing dioxin; and (3) filtering the first Part of the emulsified solution of dioxin and leaving the soil containing dioxin; (4) adding a microorganism decomposing dioxin to the soil containing dioxin; and (5) allowing the soil containing dioxin to be subjected to biodegradation.

The method for treating dioxin-containing soil according to an embodiment of the present invention is firstly: (1) providing an emulsified solution. In this step, the emulsified solution contains vegetable oil, biodegradable surfactant, soy lecithin, and water. The vegetable oil and water of the emulsified solution preferably have a ratio of oil to water of vegetable oil: water = 3:100 to 3:400, and the emulsified solution is a state in which oil droplets are dispersed by using water as a medium. Furthermore, in the composition of the emulsified solution, the vegetable oil may be 0.7% to 3% by weight, such as 0.74%, 1.25% or 2.89%, but is not limited thereto; the biodegradable surfactant may be by weight 0.1% to 0.4%, such as 0.1%, 0.25% or 0.38%, but is not limited thereto; the soybean lecithin may be from 0.1% to 0.5% by weight, such as 0.12%, 0.35% or 0.48%, but not limited thereto This; and the rest of the weight is complemented by water. The vegetable oil can be soybean oil. The biodegradable surfactant enables water-insoluble vegetable oil to be dissolved in water and in the environment Natural decomposition, no harmful substances in the environment, in line with environmental protection needs. The biodegradable surfactant may be, for example, a natural sapindus extract saponin, but is not limited thereto.

Further, in the emulsified solution, a multivitamin composition may be additionally included. The multivitamin composition comprises, for example, at least one of vitamin B group, vitamins A, C, D, E, and K, or any combination thereof, to promote microbial growth, in a ratio of about 0.01% to 0.02% by weight, For example, it is 0.015%, 0.017% or 0.019%, but is not limited thereto. Preferably, the emulsified solution may additionally comprise a lactate as a carbon source, such as sodium lactate, which may be from 0.01% to 0.02% by weight, such as 0.012%, 0.015% or 0.019%, but is not limited thereto.

A method for remediating soil containing Dioxin according to an embodiment of the present invention is followed by: (2) The emulsified solution and a soil containing dioxin are mixed. In this step, the volume of the emulsified solution may be 5 to 30 times the pore volume (Pore Volumn, PV for short) of the dioxin-containing soil, and may be, for example, 10, 20 or 30 times, but is not limited thereto. After mixing, since Dioxin is fat-soluble, it can be partially taken up by the oil droplets contained in the emulsified solution, so that the Dioxin-containing soil can release a first portion of Dioxin into the emulsified solution.

A method for remediating soil containing Dioxin according to an embodiment of the present invention is followed by: (3) The emulsified solution containing the first portion of dioxin is filtered off and the dioxin-containing soil is left behind. In this step, the present invention can utilize an existing screen device to filter out most of the emulsified solution containing the first portion of dioxin (for example, 95% to 99% by volume of the emulsified solution), and leave The dioxin-containing soil is subjected to a subsequent step (3); on the other hand, the present invention can select various treatment methods for concentrating the concentration of dioxin in the emulsified solution to be subsequently recovered, incinerated, solidified or biodegraded. The first part is Dioxin. After the above filtering step, the surface of the granules containing the dioxin soil still adheres to a small portion of the emulsified solution (for example, 5% to 1% by volume of the emulsified emulsion) Solution), the residual emulsified solution attached to the surface of the soil also contains a very small amount of the first part of the dioxin, and the other part of the dioxin-containing soil has the remaining part of the dioxin content.

A method for treating dioxin-containing soil according to an embodiment of the present invention is followed by: (4) adding a microorganism decomposing dioxin to the soil containing dioxin. In this step, the microorganism which can decompose dioxin is, for example, Pseudomonas mendocina NSYSU, but is not limited thereto. The Pseudomonas Mendoza was deposited with the Bioresource Conservation and Research Center (BCRC of FIRDI) of the Food Industry Development Research Institute of Taiwan on July 6, 2007. The registration number is BCRC 910356, and it has been found in the invention. Ren et al., filed on December 4, 2007 and approved by the Republic of China on July 16, 2009, No. I377249, "Microbial reagents for removing dioxin pollutants present in a contaminated medium and methods of use thereof In the invention patent. The Pseudomonas Mendocs can use pentachlorophenol as a carbon source, so it can be used to decompose environmental pollutants such as dioxin, dioxin and polycyclic aromatic hydrocarbons (PAHs), so it can be applied to the steps of the present invention. (4).

The method for rectifying the soil containing Dioxin according to an embodiment of the present invention is: (5) The dioxin-containing soil is allowed to stand for biodegradation reaction to remove a second portion of dioxin from the dioxin-containing soil. Preferably, the water content of the Dioxin-containing soil is controlled to be about 70%, and the temperature is about room temperature to an outdoor ambient temperature, such as 15 ° C, 20 ° C, 25 ° C, 30 ° C or 35 ° C. The proportion of the second part of Dioxin can be referred to the OCDD residual rate and / or OCDF residual rate in Table 3 below; at the same time, the proportion of the first part of the Dioxin is 100% minus the OCDD residual rate and / or 100% minus the OCDF residual rate.

In addition to the steps of the aforementioned remediation method, after step (5), it may be included Including one step (6): periodically check the concentration of dioxin in the soil containing Dioxin to confirm the whole The effect of treatment. If the concentration of dioxin in the Dioxin-containing soil still exceeds the environmental regulations, proceed to step (5) until the residual rate of dioxin falls below a predetermined target value.

In order to verify the effectiveness of the dioxin-containing soil treatment method of the present invention, the experiment was carried out as follows.

1. Contaminated soil collection and treatment: Dioxin contaminated soil originated from the Tainan Sinopec (Taiwan) Anshun plant remediation site, which previously used the mercury electrode method to mass produce pentachlorophenol as a pesticide and firewood preservative. The raw material, and Dioxin is a by-product of the pentachlorophenol process.

On November 11, 1999, the research team collected about 15 cm of Dioxin-contaminated soil on the surface of the PeCure plant of Sinopec Anshun Plant in Tainan City. All samples were packed in sealed boxes to avoid exposure to dioxin-contaminated soil. The collected contaminated soil is first removed from branches, weeds, gravel and other debris, and the large clods are crushed and mixed evenly, and then the soil is dried in a freeze-dried manner and sieved through a mesh of 35 mesh (500 μm). Fill in the sample vial and store in a 4 ° C freezer for later use.

2. Epoxy solution cleaning Dioxin soil: 10 g of the above soil samples were separately placed in 6 brown glass bottles, and the soil PV was calculated, and 5, 10, 20 and 30 times PV emulsification solution was rinsed. The method is to simulate the mashing process by shaking with a horizontal oscillator at 200 rpm for 5 minutes, and the sample after leaching is centrifuged at 3000 rpm for 5 minutes to separate the solid and liquid, and then for the liquid phase (emulsified solution), solid phase (soil) OCDD (Octachlorodibenzo-p-dioxin, octachlorodibenzo-p-dioxin) and OCDF (Octachlorodibenzofuran, octachlorodibenzofuran) were analyzed. The composition of the emulsified solution is shown in Table 1, wherein the emulsified solutions A and B have different oil-water ratios, respectively. In addition, in order to make the rinsing effect An objective evaluation was obtained, and a deionized water eluent was provided as a control group. The rinsing methods and rinsing volumes of the emulsified solutions A, B and deionized water are shown in Table 2.

Please refer to Figure 1, after the experimental group 1 rinsing procedure, the results show that after doubling the emulsification solution A of the present invention as the leaching solution for the Dioxin soil, the residual OCDD in the dioxin soil is about 47%. And the residual OCDF is about 51%. When the volume of the emulsified solution (eluent) of the present invention is gradually increased to 20 times PVs, the residual OCDD in the dioxin soil is about 32%; and the residual OCDF is about 34%. When the amount of the emulsified solution of the present invention is increased to 30 times PVs, the residual OCDD and OCDF in the dioxin soil have been reduced to about 20%. In addition, The OCDD and OCDF residual rates in the soil after the rinsing in the experimental group 2 and the control group are also shown in Table 3 below. In addition, as shown in Fig. 2, after the emulsified solution A (leaching solution) of the present invention is washed with Dioxin soil by 5 times, 10 times, 20 times, 30 times PVs, the organic carbon content in the soil of Dioxin is also dripped with The washing volume is increased and the organic carbon content is increased from 0.37% to 2.53% (that is, the organic carbon carried by the emulsified solution attached to the surface of the soil particles), which can be used as a carbon source for subsequent microbial treatment.

3. Treatment of Dioxin soil with PM NSYSU bacteria: Pseudomonas mendocina NSYSU is a native strain that can be extracted from the soil of the site with pentachlorophenol as the sole carbon source. It is also found to have a good decomposition of Dioxin. The effect was provided by the research team of Professor Liu Zhongkang from the Department of Biological Sciences of National Sun Yat-Sen University. First, take 30g of the soil after rinsing solution A, add the above-mentioned PM NSYSU bacteria at a concentration of 4×10 ⁸ cells/mL, and incubate at room temperature with a horizontal shaker (OS-72) and set the rotation speed to 100 rpm. The experiment was carried out under the condition of a water content of 70%. The experimental time and the number of samples were 16 bottles per week for a total of 8 weeks, and one bottle was taken for soil Dioxin concentration detection. After 56 days, the residual rate of OCDD and OCDF in the soil could have been reduced to 16 and 17%, respectively, in terms of concentration.

Compared with the prior art, in the first stage of the dioxin-containing soil treatment method provided by the present invention, the emulsified solution is used to extract and remove most of the dioxin in the contaminated soil, and then the second stage is biodegraded. Further remove a small portion of the dioxin remaining in the contaminated soil. Since the emulsified solution can be used not only as an extract, but also directly as a nutrient source solution for microorganisms during biodegradation of dioxin, it is possible to remove the soil by using the same emulsified solution in two stages without a large amount of manpower, material and energy. The dioxin in the process simplifies the soil remediation steps, shortens the remediation time and does not require expensive equipment, achieves a reduction in remediation costs, and reduces the dioxin residue rate to less than 17%.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

Claims (10)

A method for treating soil containing dioxin, comprising the steps of: (1) providing an emulsified solution comprising vegetable oil, a biodegradable surfactant, soy lecithin, and water; (2) mixing the emulsified solution and a Dioxin soil, releasing a first portion of Dioxin in the Dioxin soil to the emulsified solution; (3) filtering out the emulsified solution containing the first portion of Dioxin, and leaving the Dioxin-containing soil; (4) adding a microorganism that decomposes dioxin to the soil containing dioxin; and (5) allowing the soil containing dioxin to be subjected to biodegradation to remove a second portion of dioxin. The method for treating dioxin-containing soil according to claim 1, wherein the ratio of vegetable oil to water of the emulsified solution is from 3:100 to 3:400. The method for treating dioxin-containing soil according to claim 1, wherein the vegetable oil accounts for 0.7% to 3% by weight of the emulsified solution, and the biodegradable surfactant accounts for the emulsification by weight. 0.1% to 0.4% of the solution, and the soybean lecithin is from 0.1% to 0.5% by weight of the emulsified solution. The method for treating dioxin-containing soil according to claim 1, wherein the emulsified solution further comprises a multivitamin composition, a lactate or a mixture thereof. The method for treating dioxin-containing soil according to claim 4, wherein the multivitamin composition accounts for 0.01% by weight of the emulsified solution. Up to 0.02%, the lactate is from 0.01% to 0.02% by weight of the emulsified solution. The method for treating dioxin-containing soil according to claim 1, wherein the vegetable oil is soybean oil. The method for treating dioxin-containing soil according to claim 1, wherein in the step (2), the emulsified solution is used in an amount of 5 to 30 times the pore volume of the dioxin-containing soil. The method for retreating the dioxin-containing soil according to claim 1, wherein in the step (4), the microorganism capable of decomposing dioxin is Pseudomonas mendocina NSYSU. The method for treating dioxin-containing soil according to claim 1, wherein in the step (5), the water content of the dioxin-containing soil is 70%. The method for remediation of the dioxin-containing soil according to claim 1, wherein the step (5) further comprises a step (6): periodically detecting the concentration of dioxin in the soil containing dioxin to confirm the remediation effect.