Combined treatment method for polluted soil and carbon emission reduction and system utilizing combined treatment method

Abstract

The invention belongs to the technical field of environmental treatment, and particularly relates to a combined treatment method for polluted soil and carbon emission reduction and a system utilizing the combined treatment method. The polluted soil and carbon emission reduction combined treatment method provided by the invention comprises the following steps: sequentially filling a reaction tower with a mixture of polluted soil, calcium peroxide and slag, a first mixture of the polluted soil and the calcium peroxide and a second mixture of the polluted soil and the calcium peroxide from bottom to top; the reaction tower filled with the filler is obtained; the content of calcium peroxide in the second mixture is higher than that of the first mixture; activating the filler in the reaction tower filled with the filler so as to decompose organic pollutants in the polluted soil, and then introducing waste gas containing carbon dioxide to perform carbon immobilization, so as to respectively obtain purified soil and purified waste gas; the activating treatment mode comprises the step of introducing steam into the reaction tower. The synergistic interaction of soil pollutant removal and carbon immobilization is achieved, industrial waste heat and waste are fully utilized, and the resource utilization rate is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental governance, and in particular relates to a combined governance method for contaminated soil and carbon emission reduction and a system utilizing the same. Background Art

[0002] The petrochemical industry produces a large amount of petroleum hydrocarbon pollutants and flue gas CO2 during its production and operation. At the same time, the petrochemical industry also causes serious land pollution, which requires the restoration of polluted sites. Traditional petrochemical pollution site restoration methods have significant disadvantages, and their carbon emissions are large, which brings a heavy additional burden to the ecological environment. In addition, although the existing flue gas carbon capture technology can capture CO2 to a certain extent, it is difficult to promote and apply it on a large scale in actual industrial scenarios due to factors such as high cost and complex process.

[0003] In the specific research field of contaminated soil remediation technology, although the permeable reaction wall (PRB) technology has shown certain advantages in the remediation of some contaminated sites due to its high efficiency, economy and strong adaptability, most of the current research focuses on the treatment of specific pollutants, and there is a serious lack of exploration in the face of complex pollution and multi-media synergistic remediation. More importantly, most of the current remediation plans regard pollution reduction and carbon reduction as two independent processes, and fail to effectively integrate carbon capture and solidification links in the site remediation process, which not only leads to a significant increase in remediation costs, but also fails to fully tap the maximum potential for emission reduction, making it difficult to achieve a win-win situation of environmental and economic benefits. Summary of the invention

[0004] In view of this, the present invention provides a combined treatment method for contaminated soil and carbon emission reduction and a system utilizing the same. The method provided by the present invention can simultaneously achieve the treatment of contaminated soil and the solidification of carbon dioxide, and the treatment method is simple, thereby reducing the cost of environmental treatment.

[0005] In order to solve the above technical problems, the present invention provides a method for the joint treatment of contaminated soil and carbon emission reduction, comprising the following steps: The mixture of contaminated soil, calcium peroxide and slag, the first mixture of contaminated soil and calcium peroxide and the second mixture of contaminated soil and calcium peroxide are sequentially filled into the reaction tower from bottom to top to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than the content of calcium peroxide in the first mixture of contaminated soil and calcium peroxide; The filler in the reaction tower filled with filler is activated to decompose organic pollutants in the contaminated soil, and then waste gas containing carbon dioxide is introduced to fix carbon to obtain purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower.

[0006] Preferably, the contaminated soil includes contaminated soil from a petrochemical site, and the average particle size of the contaminated soil is ≤2 mm; The slag includes slag from a steel plant, and the average particle size of the slag is ≤5 mm; The calcium peroxide has a purity of 30-60%, an active oxygen content of ≥18%, and an average particle size of 100-300 μm; The organic pollutants include benzene series and / or polycyclic aromatic hydrocarbons.

[0007] Preferably, the mass ratio of contaminated soil to slag in the mixture of contaminated soil, calcium peroxide and slag is 1:0.6~1:0.5~2; The height of the mixture of contaminated soil, calcium peroxide and slag accounts for 33-39% of the total height of all fillers in the reaction tower.

[0008] Preferably, the mass ratio of contaminated soil to calcium peroxide in the first mixture of contaminated soil and calcium peroxide is 1:0.3-1; The height of the first mixture of contaminated soil and calcium peroxide accounts for 32-39% of the total height of all fillers in the reaction tower.

[0009] Preferably, the mass ratio of contaminated soil to calcium peroxide in the second mixture of contaminated soil and calcium peroxide is 1:1 to 1.5; The height of the second mixture of contaminated soil and calcium peroxide accounts for 22-29% of the total height of all fillers in the reaction tower.

[0010] Preferably, the temperature of the steam is 90-120° C., the flow rate of the steam is 0.5-3.0 L / min, and the time for passing the steam is 2-6 hours.

[0011] Preferably, the volume concentration of carbon dioxide in the waste gas containing carbon dioxide is 15-50%; The flow rate of the waste gas containing carbon dioxide is 1.0-2.0 L / min, and the time of passing the waste gas containing carbon dioxide is 2-4 hours.

[0012] Preferably, the pH value of the system after carbon fixation is 7 to 10; The carbon fixation further comprises: The tail gas after carbon fixation is recovered and condensed to obtain recovered water and recovered tail gas containing carbon dioxide respectively; The effluent is collected at the bottom of the reaction tower.

[0013] The present invention also provides a system utilized in the combined treatment method for contaminated soil and carbon emission reduction described in the above technical solution, comprising a reaction tower 1, a filler conveying unit 2 connected to the top inlet of the reaction tower 1, a carbon dioxide-containing waste gas conveying unit 3 connected to the bottom inlet of the reaction tower 1, and a steam conveying unit 4 connected to the bottom inlet of the reaction tower 1.

[0014] Preferably, it also includes a tail gas recovery unit connected to the top outlet of the reaction tower 1 and a water collection unit connected to the bottom outlet of the reaction tower 1.

[0015] The present invention provides a combined treatment method for contaminated soil and carbon emission reduction, comprising the following steps: filling a mixture of contaminated soil, calcium peroxide and slag, a first mixture of contaminated soil and calcium peroxide and a second mixture of contaminated soil and calcium peroxide into a reaction tower from bottom to top in sequence to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than the content of calcium peroxide in the first mixture of contaminated soil and calcium peroxide; activating the fillers in the reaction tower filled with fillers to decompose organic pollutants in the contaminated soil, and then introducing waste gas containing carbon dioxide for carbon fixation to obtain purified soil and purified waste gas respectively; the activation treatment method comprises introducing steam into the reaction tower. The present invention makes full use of boiler room steam and flue gas (waste gas containing carbon dioxide) two industrial wastes, alternately blowing them into the reaction tower, and cleverly activates calcium peroxide in the reaction tower to form an advanced oxidation system (AOPs); the high temperature and moisture provided by the steam can effectively promote the activation of calcium peroxide, facilitate the decomposition of organic pollutants, and significantly improve the pollutant removal efficiency. At the same time, during the oxidation process, the alkaline product of the oxidant (calcium hydroxide) reacts with the flue gas CO2, successfully achieving carbon fixation and converting the originally harmful greenhouse gas into stable carbonates. The method provided by the present invention not only achieves the synergistic effect of soil pollutant removal and carbon fixation, but also makes full use of industrial waste heat and waste, greatly improves resource utilization, and effectively solves the problem of low efficiency of pollutant removal and carbon fixation in the prior art, opening up a new feasible path for the field of contaminated site remediation and carbon emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a system used in the combined treatment method for contaminated soil and carbon emission reduction provided by the present invention, wherein 1 is a reaction tower, 2 is a filler conveying unit, 3 is a carbon dioxide-containing waste gas conveying unit, 4 is a steam conveying unit, and 5 is an air compressor; Figure 2 The figure is a flow chart of the combined treatment of contaminated soil and carbon emission reduction according to the embodiment. DETAILED DESCRIPTION

[0017] The present invention provides a combined treatment method for contaminated soil and carbon emission reduction, comprising the following steps: The mixture of contaminated soil, calcium peroxide and slag, the first mixture of contaminated soil and calcium peroxide and the second mixture of contaminated soil and calcium peroxide are sequentially filled into the reaction tower from bottom to top to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than the content of calcium peroxide in the first mixture of contaminated soil and calcium peroxide; The filler in the reaction tower filled with filler is activated to decompose organic pollutants in the contaminated soil, and then waste gas containing carbon dioxide is introduced to fix carbon to obtain purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower.

[0018] The present invention sequentially fills a reaction tower with a mixture of contaminated soil, calcium peroxide and slag, a first mixture of contaminated soil and calcium peroxide and a second mixture of contaminated soil and calcium peroxide from bottom to top into a reaction tower to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than the content of calcium peroxide in the first mixture of contaminated soil and calcium peroxide. As a specific embodiment of the present invention, the contaminated soil may include contaminated soil derived from a petrochemical site, and the average particle size of the contaminated soil may be ≤2 mm, and may also be 1-2 mm; the organic pollutants in the contaminated soil may include benzene series and / or polycyclic aromatic hydrocarbons, the benzene series may include benzene and / or toluene, and the polycyclic aromatic hydrocarbons may include one or more of naphthalene, pyrene and benzo[a]pyrene, and may specifically be naphthalene, a mixture of pyrene and benzo[a]pyrene, a mixture of naphthalene and pyrene, a mixture of naphthalene and benzo[a]pyrene, a mixture of pyrene and benzo[a]pyrene, naphthalene, pyrene or benzo[a]pyrene; the mass concentration of benzene series in the contaminated soil may be 1-100 mg / kg, and may also be 10-95 mg / kg, and may further be 20-80 mg / kg; the mass concentration of polycyclic aromatic hydrocarbons in the contaminated soil may be 1-15 mg / kg, and may also be 11-13 mg / kg. As a specific embodiment of the present invention, the slag may include slag or coal slag from a steel plant, and the average particle size of the slag may be ≤5 mm, and may also be 1-4 mm; the components in the slag mainly include CaO, MgO, and also include a small amount of Al2O3 and Fe2O3; the slag mainly provides alkaline substances (such as CaO, MgO, etc.) and physical support, which can neutralize the acidic substances (such as carbon dioxide) generated in the treatment process (such as the organic matter degradation process) and promote the formation of carbonates.

[0019] As a specific embodiment of the present invention, the calcium peroxide can be industrial-grade calcium peroxide powder, the purity of the calcium peroxide can be 30-60%, or 40-50%; the active oxygen content of the calcium peroxide can be ≥18%, or 19-21%; the average particle size of the calcium peroxide can be 100-300 μm, or 120-260 μm. In the present invention, the calcium peroxide acts as an activator of the advanced oxidation system, provides oxidation capacity, activates the generation of hydroxyl radicals (·OH), and decomposes organic pollutants in the contaminated soil.

[0020] As a specific embodiment of the present invention, the mixture of contaminated soil, calcium peroxide and slag is obtained by mixing contaminated soil and slag, and the mixing can be carried out under stirring conditions. The present invention has no special limitation on the stirring, as long as the mixture can be evenly mixed; the first mixture of contaminated soil and calcium peroxide and the second mixture of contaminated soil and calcium peroxide are obtained by mixing contaminated soil and calcium peroxide, and the mixing can be carried out under stirring conditions. The present invention has no special limitation on the stirring, as long as the mixture can be evenly mixed.

[0021] As a specific embodiment of the present invention, the mass ratio of contaminated soil to slag in the mixture of contaminated soil, calcium peroxide and slag can be 1:0.6~1:0.5~2, or 1:0.8:0.8~1.5; the height of the mixture of contaminated soil, calcium peroxide and slag can account for 33~39% of the total height of all fillers in the reaction tower, or 33~38%, or further 35~37%. As a specific embodiment of the present invention, the mass ratio of contaminated soil to calcium peroxide in the first mixture of contaminated soil and calcium peroxide can be 1:0.3~1, or 1:0.5~0.8; the height of the first mixture of contaminated soil and calcium peroxide can account for 32~39% of the total height of all fillers in the reaction tower, or 33~38%, or further 35~37%. As a specific embodiment of the present invention, the mass ratio of contaminated soil to calcium peroxide in the second mixture of contaminated soil and calcium peroxide can be 1:1-1.5, or 1:1.2-1.3; the height of the second mixture of contaminated soil and calcium peroxide can account for 22-29% of the total height of all fillers in the reaction tower, or 23-28%, or further 24-26%.

[0022] As a specific embodiment of the present invention, the density of all fillers in the reaction tower can be 100-300 kg / m³, or 150-250 kg / m³, based on the total volume of the reaction tower. In the present invention, the mixture layer of the contaminated soil, calcium peroxide and slag provides sufficient alkaline substances for the reaction, helps to adjust the pH value of the system, and effectively reacts with the reaction gas (such as steam and CO2). The slag in the mixture helps to provide a sufficient alkaline environment and supports the formation of carbonates. The iron element in the slag can also be used as a catalyst to catalyze the activation of calcium peroxide; the first mixture of the contaminated soil and calcium peroxide contacts the calcium peroxide with the contaminated soil, and promotes the degradation of organic pollutants through advanced oxidation reactions (AOPs). Due to the high reactivity of CaO2 in this layer, it can produce a large amount of oxidative free radicals under the action of high-temperature steam, effectively decomposing pollutants such as benzene series and polycyclic aromatic hydrocarbons; the second mixture of the contaminated soil and calcium peroxide contains more CaO2, which can ensure that the reaction continues, and at the same time provide a strong oxidizing ability to promote the decomposition of organic pollutants.

[0023] After obtaining the reaction tower filled with fillers, the present invention activates the fillers in the reaction tower filled with fillers to decompose organic pollutants in the contaminated soil, and then introduces waste gas containing carbon dioxide for carbon fixation to obtain purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower, and the steam can be introduced from the bottom of the reaction tower. As a specific embodiment of the present invention, the steam can be steam generated by a boiler, making full use of the remaining heat; the temperature of the steam can be 90~120℃, and can also be 100~110℃. In the present invention, when the temperature of the steam is lower than 90℃, the advanced oxidation system (AOPs) cannot be effectively activated, and when the temperature of the steam is higher than 120℃, the filler will fail and waste energy. As a specific embodiment of the present invention, the flow rate of the steam can be 0.5~3.0L / min, can also be 1.0~2.0L / min, and can further be 1.5~2.5L / min; the time for introducing steam can be 2~6h, and can also be 3~5h. The present invention limits the steam flow rate within the above range to facilitate the reaction to proceed fully. When the flow rate is too low, the reaction will be incomplete, and when the flow rate is too high, heat loss will occur. The present invention activates calcium peroxide (CaO2) and other oxidants to produce strong oxidants such as hydroxyl radicals (·OH) through activation treatment. These free radicals can effectively degrade organic pollutants in the soil; at the same time, the alkaline substances CaO and MgO in the polluted soil and slag react with water in the steam to generate Ca(OH)2 and Mg(OH)2, and the pH value of the system is stable at 7~14. The generated Ca(OH)2 and Mg(OH)2 provide conditions for subsequent carbon fixation reactions. Chimney CO2 reacts with alkaline substances to form stable carbonates, which not only achieves carbon capture, but also solves the problem of inhibition of the oxidation system by the alkaline environment. The process ensures the removal of organic pollutants in the soil and the coordinated optimization of carbon fixation by dynamically controlling the pH value.

[0024] As a specific embodiment of the present invention, waste gas containing carbon dioxide can be introduced from the bottom of the reaction tower, and the waste gas containing carbon dioxide can be boiler flue gas, and the volume concentration of carbon dioxide in the waste gas containing carbon dioxide can be 15-50%, 20-40%, and further 30-38%; the flue gas can also be subjected to dust removal before being introduced, and the dust obtained by the dust removal can be mixed with slag for use. As a specific embodiment of the present invention, the position for introducing waste gas containing carbon dioxide can be the position where the bottom of the reaction tower intersects with the central axis of the reaction tower. In the present invention, too low CO2 concentration (less than 15%) may lead to low carbonate generation efficiency, thereby reducing carbon capture and carbon fixation effects; too high CO2 concentration (more than 50%) may lead to too fast reaction speed, causing problems such as pipeline blockage. As a specific embodiment of the present invention, the flow rate of the exhaust gas containing carbon dioxide can be 1.0~2.0L / min, or 1.2~1.7L / min, or further 1.4~1.6L / min; the time for introducing the exhaust gas containing carbon dioxide can be 2~4h, or 2.5~3.5h, or further 3~3.3h.

[0025] As a specific embodiment of the present invention, during the carbon fixation process, CO2 reacts with Ca(OH)2 and Mg(OH)2 generated in the filler to form stable carbonates (CaCO3, MgCO3). This process not only achieves carbon fixation, but also dynamically adjusts the pH value of the system to a neutral range (6.5~8.5).

[0026] As a specific embodiment of the present invention, the pH value of the system after carbon fixation can be 7-10, or 8-9.

[0027] The treatment method provided by the present invention makes full use of the waste heat and water vapor resources of industrial boilers, recovers steam and CO2 and applies them to the pollution treatment process, thereby realizing efficient recycling of resources; the filler design combines the multifunctionality of soil, CaO2 and slag, which not only supports the degradation of pollutants but also enhances the efficiency of carbonate generation; the removal rate of the present invention for benzene series is ≥90%, the removal rate of polycyclic aromatic hydrocarbons is ≥85%, and the carbonate generation rate is ≥80%.

[0028] As a specific embodiment of the present invention, the carbon fixation further comprises: The tail gas after carbon fixation is recovered and condensed to obtain recovered water and recovered tail gas containing carbon dioxide respectively; The effluent is collected at the bottom of the reaction tower.

[0029] The present invention can recover all the unreacted carbon dioxide through the tail gas reflux pipeline for recycling; the tail gas is passed through a condenser to fully extract water, which is conducive to the recycling of the water.

[0030] In the present invention, the effluent contains organic matter and carbonate (calcium carbonate, magnesium carbonate).

[0031] The method provided by the present invention has significant steam waste heat utilization rate, pollutant removal rate and carbon fixation efficiency; the present invention divides the hot steam and flue gas in the boiler room into two pipes and alternately blows them into the reaction tower, the steam can provide sufficient heat and moisture to activate the advanced oxidation system (AOPs), the catalyst in the liquid system (such as iron contained in soil or slag) can activate calcium peroxide, and the moisture in the steam can provide a liquid phase for the system; at the same time, the increase in temperature can promote the progress of the catalytic system, generate more hydroxyl radicals (·OH), thereby decomposing organic pollutants such as benzene series and polycyclic aromatic hydrocarbons in the soil. Carbon dioxide (CO2) in flue gas reacts with alkaline substances to form stable carbonates. In this process, CO2 reacts with substances such as Ca(OH)2 and Mg(OH)2 from the soil to generate carbonates such as CaCO3 and MgCO3, which can achieve carbon capture and carbon fixation. The present invention can maintain high temperature conditions and sufficient moisture in the reaction tower to activate advanced oxidation reactions by alternately introducing hot steam and flue gas, and can also use the reaction of CO2 with alkaline substances to regulate the salinization problem caused by calcium peroxide products (calcium hydroxide), thereby achieving a cycle of efficient pollutant removal and carbon fixation.

[0032] The present invention also provides a system for the combined treatment method of contaminated soil and carbon emission reduction described in the above technical solution, comprising a reaction tower 1, a filler delivery unit 2 connected to the top inlet of the reaction tower 1, a waste gas delivery unit 3 containing carbon dioxide connected to the bottom inlet of the reaction tower 1, and a steam delivery unit 4 connected to the bottom inlet of the reaction tower 1. As a specific embodiment of the present invention, a tree-like pipeline is arranged in the reaction tower, which is conducive to the uniform distribution of gas (steam, waste gas containing carbon dioxide), can better contact with fillers (contaminated soil, slag, calcium peroxide), and improve the reaction efficiency.

[0033] As a specific embodiment of the present invention, the carbon dioxide-containing waste gas delivery unit 3 and the steam delivery unit 4 are connected in parallel to the reaction tower 1 through an air compressor.

[0034] As a specific embodiment of the present invention, the system may further include a tail gas recovery unit connected to the top outlet of the reaction tower 1 and a water collection unit connected to the bottom outlet of the reaction tower 1 .

[0035] Figure 1This is a structural schematic diagram of the system for the combined treatment method for contaminated soil and carbon emission reduction provided by the present invention, wherein 1 is a reaction tower, 2 is a filler conveying unit, 3 is a carbon dioxide-containing waste gas conveying unit, 4 is a steam conveying unit, and 5 is an air compressor.

[0036] Figure 2 The figure is a flow chart of the combined treatment of contaminated soil and carbon emission reduction according to the embodiment.

[0037] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0038] Embodiment Figure 2 The process shown is used to treat contaminated soil and carbon dioxide in flue gas.

[0039] Example 1 In the vicinity of a petrochemical site, the soil is seriously polluted by benzene series, and the benzene content in the polluted soil is 95 mg / kg. The remediation method of the present invention is used for treatment: First, the filler is prepared: the materials are contaminated soil with an average particle size of 2 mm, industrial-grade CaO2 with an active oxygen content of 18% and an average particle size of 200 μm, and industrial coal slag with an average particle size of 5 mm and the main components of CaO, MgO and a small amount of Al2O3 and Fe2O3; the contaminated soil, CaO2 and industrial coal slag are stirred and mixed in a mass ratio of 1:0.8:1 for 45 minutes and then loaded into the reaction tower as the lower filler (accounting for 37% of the total height of the filler); the contaminated soil and CaO2 are stirred and mixed in a mass ratio of 1:0.5 for 40 minutes and then loaded into the reaction tower as the middle filler (accounting for 37% of the total height of the filler); the contaminated soil and CaO2 are stirred and mixed in a mass ratio of 1:1.2 for 50 minutes and then loaded into the reaction tower as the upper filler (accounting for 26% of the total height of the filler); the total amount of filler in the reaction tower is 200 kg / m 3 .

[0040] Coal furnace steam was introduced, and steam with a temperature of 110°C was injected from the bottom of the reaction tower at a flow rate of 1.5L / min through a hollow ring-walled glass tube and continuously introduced for 4 hours for activation treatment. In this process, the heat and moisture of the steam activated the advanced oxidation system (AOPs), generating a large number of hydroxyl radicals (·OH), which effectively decomposed the benzene series in the soil. At the same time, the alkaline substances in the soil and slag reacted with water, causing the pH value of the system to rise.

[0041] After steam oxidation is completed, the flue gas from the coal furnace is dedusted and the CO2 concentration is stably maintained at 30%. The flue gas is injected from the bottom of the reaction tower through a hollow glass pipe at a flow rate of 1.5L / min for 3 hours to carry out carbon fixation. At this time, CO2 reacts rapidly with the Ca(OH)2 and Mg(OH)2 generated in the filler to efficiently form stable carbonates (CaCO3, MgCO3), achieving carbon fixation and accurately adjusting the pH value of the system to 7.5.

[0042] During the tail gas treatment stage, all unreacted CO2 is recovered and recycled through the tail gas reflux pipeline, and the remaining tail gas is fully extracted with water through the condenser.

[0043] Finally, the treated water samples were collected from the bottom of the reaction tower for testing. The removal rate of benzene series reached 93%, the removal rate of polycyclic aromatic hydrocarbons reached 88%, and the carbonate generation rate was 89%. According to XRD analysis, the main crystal forms of carbonate products are calcite (CaCO3) and magnesite (MgCO3), and their characteristic peaks appear clearly at 29.4° (CaCO3) and 42.9° (MgCO3), respectively.

[0044] Example 2 At a certain industrial waste site, the benzene content in the contaminated soil was 12 mg / kg.

[0045] The filling was carried out according to the method of Example 1, except that the active oxygen content of CaO2 was 19%, the average particle size of the contaminated soil was 1.8 mm, the average particle size of the slag was 3 mm (the main components included CaO, MgO and a small amount of Al2O3 and Fe2O3), and the total amount of filler was determined to be 230 kg / m according to the volume of the reaction tower. 3 ; The stirring time when mixing the materials is 50 minutes.

[0046] Coal furnace steam at a temperature of 105°C was injected from the bottom of the reaction tower at a flow rate of 2.0L / min for 5 hours to activate AOPs to decompose pollutants and increase the pH value of the system; the coal furnace flue gas was then dust-removed and flue gas with a CO2 concentration of 40% was injected from the bottom of the reaction tower at a flow rate of 1.2L / min for 3.5 hours to react with the generated alkaline substances to achieve carbon fixation and pH adjustment.

[0047] Tail gas recovery, water extraction and effluent collection were performed according to the method of implementation 1. After testing, the removal rate of benzene series in the water sample (effluent) reached 90%, the removal rate of polycyclic aromatic hydrocarbons reached 86%, and the carbonate generation rate was 84%. The crystal form and characteristic peaks of the product detected by XRD were consistent with those of Example 1, indicating that the present invention can effectively remove pollutants and achieve a certain degree of carbon fixation under different pollution scenarios, verifying its feasibility and effectiveness.

[0048] Example 3 In a contaminated site in a shutdown area of ​​a petrochemical plant, the soil was subject to complex pollution, with a benzene content of 17 mg / kg, a naphthalene content of 11 mg / kg, and heavy metal lead (Pb) content of 0.6 mg / kg and mercury (Hg) content of 0.08 mg / kg.

[0049] Prepare the filler: Fill the filler according to the method of Example 1, except that the filler is contaminated soil with an average particle size of 1.8 mm, industrial-grade CaO2 with an active oxygen content of 21% and a particle size in the range of 120-260 μm, and industrial waste slag with a particle size not exceeding 4 mm and main components including CaO, MgO and a small amount of Al2O3 and Fe2O3. The mixed materials are stirred in a planetary mixer for 58 minutes.

[0050] Next, coal furnace steam at a temperature of 115°C was injected from the bottom of the reaction tower through a hollow ring-walled glass tube at a flow rate of 1.9 L / min for activation treatment, and the injection was continued for 4.8 hours; the steam activated advanced oxidation system (AOPs) produced a large number of hydroxyl radicals (·OH) to decompose organic pollutants, and the alkaline substances in the soil and slag reacted with water to increase the pH value of the system; after steam oxidation, the coal furnace flue gas was dust-removed and the preliminary purified flue gas with a CO2 concentration of 38% was injected from the bottom of the reaction tower through a hollow glass pipe at a flow rate of 1.7 L / min for 3.6 hours for carbon fixation, and CO2 reacted with the generated Ca(OH)2 and Mg(OH)2 to form carbonate to achieve carbon fixation and adjust the pH value to 7.9.

[0051] During the tail gas treatment stage, all unreacted CO2 is recovered and recycled through the tail gas reflux pipeline, and the remaining tail gas is fully extracted with water through the condenser.

[0052] Finally, the water sample at the bottom of the reaction tower was tested, and the removal rate of benzene series was 94%, the removal rate of naphthalene was 90%, and the carbonate generation rate was 91%. XRD analysis showed that the main crystal forms of the products were calcite (CaCO3) and magnesite (MgCO3), and the characteristic peaks appeared at 29.4° (CaCO3) and 42.9° (MgCO3), respectively. The content of lead (Pb) in the treated soil was reduced to 0.15mg / kg, and the content of mercury (Hg) was reduced to 0.02mg / kg.

[0053] Example 4 At a site where a chemical leak had occurred and the subsequent cleanup was not thorough, the soil pollution was highly complex. The benzene content in the soil was 17 mg / kg, the toluene content was 13 mg / kg, the pyrene content was 11 mg / kg, and the benzo[a]pyrene content was 7 mg / kg. There were also heavy metal cadmium (Cd) content of 0.6 mg / kg and chromium (Cr) content of 0.4 mg / kg.

[0054] The filler is loaded according to the method of Example 1, except that the filler is contaminated soil with an average particle size of 1.6 mm, industrial-grade CaO2 with an active oxygen content of 21% and a particle size in the range of 120-280 μm, and industrial waste slag with a particle size not exceeding 4 mm and main components including CaO, MgO and a small amount of Al2O3 and Fe2O3. The mixed materials are stirred in a high-power mixer for 52 minutes.

[0055] Next, coal furnace steam at a temperature of 100°C was injected upward from the bottom of the reaction tower through a hollow ring-walled glass tube at a flow rate of 1.6L / min for activation treatment, and was continuously introduced for 4.6 hours; the heat and moisture of the steam activated the advanced oxidation system (AOPs), decomposing benzene and polycyclic aromatic hydrocarbons in the soil. At the same time, the alkaline substances in the soil and slag reacted with water, and the pH value of the system increased.

[0056] After steam oxidation is completed, the flue gas from the coal furnace is dust-removed and the CO2 concentration is stabilized at 35%. The preliminarily purified flue gas is injected from the bottom of the reaction tower through a highly sealed hollow glass pipe at a flow rate of 1.7L / min for carbon fixation. The injection time is 3.4h, achieving carbon fixation and adjusting the pH value of the system to 7.8.

[0057] In the tail gas treatment stage, all unreacted CO2 is recovered and recycled through a reflux pipeline, and the remaining tail gas is fully extracted with water through a condenser.

[0058] Finally, the treated effluent samples were collected from the bottom of the reaction tower for testing. The removal rate of benzene series reached 94%, the removal rate of polycyclic aromatic hydrocarbons reached 91%, and the carbonate generation rate was 90%. According to XRD analysis, the main crystal forms of carbonate products are calcite (CaCO3) and magnesite (MgCO3), and their characteristic peaks are clearly shown at 29.4° (CaCO3) and 42.9° (MgCO3), further highlighting the excellent performance of the present invention in treating complex polluted sites, especially in the face of multiple organic pollutants and heavy metal composite pollution.

[0059] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for the joint treatment of polluted soil and carbon emission reduction, characterized in that: The following steps are involved: The mixture of contaminated soil, calcium peroxide and slag, the first mixture of contaminated soil and calcium peroxide and the second mixture of contaminated soil and calcium peroxide are sequentially filled into the reaction tower from bottom to top to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than the content of calcium peroxide in the first mixture of contaminated soil and calcium peroxide; The filler in the reaction tower filled with filler is activated to decompose organic pollutants in the contaminated soil, and then waste gas containing carbon dioxide is introduced to fix carbon to obtain purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower.

2. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 is characterized in that: The contaminated soil includes contaminated soil from a petrochemical site, and the average particle size of the contaminated soil is ≤2 mm; The slag includes slag from a steel plant, and the average particle size of the slag is ≤5 mm; The calcium peroxide has a purity of 30-60%, an active oxygen content of ≥18%, and an average particle size of 100-300 μm; The organic pollutants include benzene series and / or polycyclic aromatic hydrocarbons.

3. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 or 2 is characterized in that: The mass ratio of the contaminated soil to the slag in the mixture of the contaminated soil, calcium peroxide and slag is 1:0.6~1:0.5~2; The height of the mixture of contaminated soil, calcium peroxide and slag accounts for 33-39% of the total height of all fillers in the reaction tower.

4. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 or 2, characterized in that: The mass ratio of the contaminated soil to the calcium peroxide in the first mixture of the contaminated soil and the calcium peroxide is 1:0.3-1; The height of the first mixture of contaminated soil and calcium peroxide accounts for 32-39% of the total height of all fillers in the reaction tower.

5. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 or 2, characterized in that: The mass ratio of the contaminated soil to the calcium peroxide in the second mixture of the contaminated soil and the calcium peroxide is 1:1 to 1.5; The height of the second mixture of contaminated soil and calcium peroxide accounts for 22-29% of the total height of all fillers in the reaction tower.

6. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 is characterized in that: The temperature of the steam is 90-120° C., the flow rate of the steam is 0.5-3.0 L / min, and the time for passing the steam is 2-6 hours.

7. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 is characterized in that: The volume concentration of carbon dioxide in the waste gas containing carbon dioxide is 15-50%; The flow rate of the waste gas containing carbon dioxide is 1.0-2.0 L / min, and the time of passing the waste gas containing carbon dioxide is 2-4 hours.

8. The combined treatment method for contaminated soil and carbon emission reduction according to claim 1 is characterized in that: The pH value of the system after carbon fixation is 7-10; The carbon fixation further comprises: The tail gas after carbon fixation is recovered and condensed to obtain recovered water and recovered tail gas containing carbon dioxide respectively; The effluent is collected at the bottom of the reaction tower.

9. The system used in the combined treatment method for contaminated soil and carbon emission reduction according to any one of claims 1 to 8 comprises a reaction tower (1), a filler conveying unit (2) connected to the top inlet of the reaction tower (1), a carbon dioxide-containing waste gas conveying unit (3) connected to the bottom inlet of the reaction tower (1), and a steam conveying unit (4) connected to the bottom inlet of the reaction tower (1).

10. The system according to claim 9, characterized in that: It also comprises a tail gas recovery unit connected to the top outlet of the reaction tower (1) and a water collection unit connected to the bottom outlet of the reaction tower (1).

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