A combined treatment method for contaminated soil and carbon emission reduction and a system using the same

Abstract

The present invention belongs to the field of environmental governance technology, and specifically relates to a joint governance method for contaminated soil and carbon emission reduction and a system for its use. The joint governance method for contaminated soil and carbon emission reduction provided by the present invention comprises the following steps: 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 are sequentially filled into a reaction tower from bottom to top from a reaction tower to obtain a reaction tower filled with fillers; the content of calcium peroxide in the second mixture is higher than that in the first mixture; the fillers in the reaction tower filled with fillers are activated to decompose organic pollutants in the contaminated soil, and then waste gas containing carbon dioxide is introduced for carbon fixation to obtain purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower. The synergistic effect of soil pollutant removal and carbon fixation is achieved, industrial waste heat and waste are fully utilized, and resource utilization is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental governance, and particularly relates to a combined treatment method for polluted soil and carbon emission reduction and a system using the same. Background Art

[0002] The petrochemical industry will generate a large amount of petroleum hydrocarbon pollutants and flue gas CO 2 during its production and operation process; at the same time, the petrochemical industry will also cause serious pollution to the land, and it is necessary to repair the polluted sites. The traditional petrochemical polluted site repair methods have significant drawbacks, with large carbon emissions, bringing a heavy additional burden to the ecological environment. And the existing flue gas carbon capture technologies, although they can capture CO 2 to a certain extent, are difficult to be widely applied on a large scale in actual industrial scenarios due to factors such as high cost and complex process.

[0003] Delving into the specific research field of polluted soil remediation technologies, although the permeable reactive barrier (PRB) technology has shown certain advantages in the remediation of some polluted sites with its characteristics of high efficiency, economy, and strong adaptability, however, current research mostly focuses on the treatment of specific pollutants, and there is a serious lack of exploration in the face of combined pollution and multi-media collaborative remediation. More critically, most current remediation schemes regard pollution reduction and carbon reduction as two independent processes, and the carbon capture and solidification links are not effectively integrated during the site remediation process, which not only leads to a significant increase in remediation costs, but also fails to fully exert the maximum potential of carbon emission reduction, and it is 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 polluted soil and carbon emission reduction and a system using the same. The method provided by the present invention can simultaneously achieve the treatment of polluted soil and the solidification of carbon dioxide, and the treatment method is simple, reducing the cost of environmental governance.

[0005] To solve the above technical problems, the present invention provides a combined treatment method for polluted soil and carbon emission reduction, including the following steps:

[0006] A mixture of polluted soil, calcium peroxide and slag, a first mixture of polluted soil and calcium peroxide, and a second mixture of polluted soil and calcium peroxide are filled into a reaction tower from bottom to top in sequence by the reaction tower to obtain a reaction tower filled with packing; the content of calcium peroxide in the second mixture of polluted soil and calcium peroxide is higher than that in the first mixture of polluted soil and calcium peroxide;

[0007] The packing in the reaction tower filled with packing is activated to decompose organic pollutants in contaminated soil, and then waste gas containing carbon dioxide is introduced for carbon fixation, obtaining purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower.

[0008] Preferably, the contaminated soil includes contaminated soil from a petrochemical site, and the average particle size of the contaminated soil is ≤ 2 mm;

[0009] The slag includes slag from a steel plant, and the average particle size of the slag is ≤ 5 mm;

[0010] The purity of the calcium peroxide is 30 - 60%, the active oxygen content is ≥ 18%, and the average particle size is 100 - 300 μm;

[0011] The organic pollutants include benzene series and / or polycyclic aromatic hydrocarbons.

[0012] Preferably, in the mixture of the contaminated soil, calcium peroxide and slag, the mass ratio of the contaminated soil to the slag is 1:0.6 - 1:0.5 - 2;

[0013] The height of the mixture of the contaminated soil, calcium peroxide and slag accounts for 33 - 39% of the total height of all packings in the reaction tower.

[0014] Preferably, in the first mixture of the contaminated soil and calcium peroxide, the mass ratio of the contaminated soil to the calcium peroxide is 1:0.3 - 1;

[0015] The height of the first mixture of the contaminated soil and calcium peroxide accounts for 32 - 39% of the total height of all packings in the reaction tower.

[0016] Preferably, in the second mixture of the contaminated soil and calcium peroxide, the mass ratio of the contaminated soil to the calcium peroxide is 1:1 - 1.5;

[0017] The height of the second mixture of the contaminated soil and calcium peroxide accounts for 22 - 29% of the total height of all packings in the reaction tower.

[0018] 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 introducing the steam is 2 - 6 h.

[0019] Preferably, the volume concentration of carbon dioxide in the waste gas containing carbon dioxide is 15 - 50%;

[0020] The flow rate of introducing the waste gas containing carbon dioxide is 1.0 - 2.0 L / min, and the time for introducing the waste gas containing carbon dioxide is 2 - 4 h.

[0021] Preferably, the pH value of the system after carbon fixation is 7-10;

[0022] After carbon fixation, it further includes:

[0023] The tail gas after carbon fixation is recovered and condensed to obtain recovered water and recovered tail gas containing carbon dioxide respectively;

[0024] The water is collected at the bottom of the reaction tower.

[0025] The present invention also provides a system for using the combined treatment method of the above-mentioned polluted soil and carbon emission reduction, including a reaction tower 1, a packing conveying unit 2 connected to the top inlet of the reaction tower 1, an exhaust gas conveying unit 3 containing carbon dioxide 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.

[0026] Preferably, it further 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.

[0027] The present invention provides a combined treatment method for polluted soil and carbon emission reduction, including the following steps: filling a mixture of polluted soil, calcium peroxide and slag, a first mixture of polluted soil and calcium peroxide, and a second mixture of polluted soil and calcium peroxide into the reaction tower from bottom to top in sequence to obtain a reaction tower filled with packing; the content of calcium peroxide in the second mixture of polluted soil and calcium peroxide is higher than that in the first mixture of polluted soil and calcium peroxide; activating the packing in the reaction tower filled with packing to decompose organic pollutants in the polluted soil, and then introducing exhaust gas containing carbon dioxide for carbon fixation to obtain purified soil and purified exhaust gas respectively; the activation treatment method includes introducing steam into the reaction tower. The present invention makes full use of two industrial wastes, namely the steam and flue gas (exhaust gas containing carbon dioxide) from the boiler room, alternately blowing them into the reaction tower, and cleverly activating 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 (calcium hydroxide) of the oxidant reacts with the flue gas CO 2 to achieve carbon fixation successfully, converting the originally harmful greenhouse gas into stable carbonate. The method provided by the present invention not only realizes the synergistic effect of soil pollutant removal and carbon fixation, but also makes full use of industrial waste heat and waste, greatly improves the resource utilization rate, effectively solves the problem of low efficiency of pollutant removal and carbon fixation in the prior art, and opens up a new feasible path for the field of polluted site remediation and carbon emission reduction. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the system used in the combined treatment method of contaminated soil and carbon emission reduction provided by the present invention. Among them, 1 is a reaction tower, 2 is a filler conveying unit, 3 is an exhaust gas conveying unit containing carbon dioxide, 4 is a steam conveying unit, and 5 is an air compressor;

[0029] Figure 2 It is a schematic process diagram for the combined treatment of contaminated soil and carbon emission reduction in the embodiment. Specific implementation manners

[0030] The present invention provides a combined treatment method for contaminated soil and carbon emission reduction, including the following steps:

[0031] 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 filled into the reaction tower from bottom to top in sequence from the 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 that in the first mixture of contaminated soil and calcium peroxide;

[0032] The fillers in the reaction tower filled with fillers are activated to decompose organic pollutants in the contaminated soil, and then exhaust gas containing carbon dioxide is introduced for carbon fixation to obtain purified soil and purified exhaust gas respectively; the activation treatment method includes introducing steam into the reaction tower.

[0033] In the present invention, 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 are filled into a reaction tower from bottom to top in sequence from the reaction tower, obtaining a reaction tower filled with packing materials; the content of calcium peroxide in the second mixture of contaminated soil and calcium peroxide is higher than that 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 from a petrochemical site, 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, the polycyclic aromatic hydrocarbons may include one or more of naphthalene, pyrene and benzo[a]pyrene, and may specifically be a mixture of naphthalene, 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, 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 cinder from a steel plant, 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 Al 2 O 3 and Fe 2 O 3 ; the slag mainly provides alkaline substances (such as CaO, MgO, etc.) and physical support, and can neutralize acidic substances (such as carbon dioxide) generated during the treatment process (such as the organic matter degradation process) to promote the formation of carbonates.

[0034] As a specific embodiment of the present invention, the calcium peroxide may be industrial-grade calcium peroxide powder, the purity of the calcium peroxide may be 30-60%, and may also be 40-50%; the active oxygen content of the calcium peroxide may be ≥18%, and may also be 19-21%; the average particle size of the calcium peroxide may be 100-300 μm, and may also be 120-260 μm. In the present invention, the calcium peroxide serves as an activator of the advanced oxidation system, provides oxidation ability, activates the generation of hydroxyl radicals (·OH), and decomposes organic pollutants in the contaminated soil.

[0035] 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.

[0036] 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 to 1:0.5 to 2, and can also be 1:0.8:0.8 to 1.5; the height of the mixture of contaminated soil, calcium peroxide and slag can account for 33 to 39% of the total height of all fillers in the reaction tower, and can also be 33 to 38%, and can further be 35 to 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 to 1, and can also be 1:0.5 to 0.8; the height of the first mixture of contaminated soil and calcium peroxide can account for 32 to 39% of the total height of all fillers in the reaction tower, and can also be 33 to 38%, and can further be 35 to 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 to 1.5, and can also be 1:1.2 to 1.3; the height of the second mixture of contaminated soil and calcium peroxide can account for 22 to 29% of the total height of all fillers in the reaction tower, and can also be 23 to 28%, and can further be 24 to 26%.

[0037] As a specific embodiment of the present invention, based on the total volume of the reaction tower, the density of all fillers in the reaction tower can be 100 to 300 kg / m³, and can also be 150 to 250 kg / m³. In the present invention, the mixture layer of contaminated soil, calcium peroxide and slag provides sufficient alkaline substances for the reaction, helps to adjust the pH value of the system, and reacts effectively with the reaction gas (such as steam and CO 2 ), and the slag in the mixture helps to provide a sufficient alkaline environment and support the formation of carbonates. The iron element in the slag can also act as a catalyst to catalyze the activation of calcium peroxide; the first mixture of contaminated soil and calcium peroxide brings calcium peroxide into contact with contaminated soil, and promotes the degradation of organic pollutants through advanced oxidation processes (AOPs). Since CaO 2Due to its high reactivity in this layer, it can generate a large number of oxidation 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 CaO 2 It can ensure the continuation of the reaction, and at the same time provide strong oxidation ability to promote the decomposition of organic pollutants.

[0038] After obtaining the reaction tower filled with packing, the present invention activates the packing in the reaction tower filled with packing to decompose organic pollutants in the contaminated soil, and then passes in waste gas containing carbon dioxide for carbon fixation to obtain purified soil and purified waste gas respectively; the activation treatment method includes passing steam into the reaction tower, and the steam can be passed in from the bottom of the reaction tower. As a specific embodiment of the present invention, the steam can be the steam generated by a boiler, making full use of its waste heat; the temperature of the steam can be 90~120°C, or can also be 100~110°C. In the present invention, when the temperature of the steam is lower than 90°C, the advanced oxidation system (AOPs) cannot be effectively activated, and when the temperature of the steam is higher than 120°C, it will cause the packing to fail and result in energy waste. As a specific embodiment of the present invention, the flow rate of the steam can be 0.5~3.0 L / min, or can also be 1.0~2.0 L / min, and further can be 1.5~2.5 L / min; the time for passing in the steam can be 2~6 h, or can also be 3~5 h. The present invention limits the steam flow rate within the above range to facilitate the full progress of the reaction. When the flow rate is too low, the reaction will be insufficient, and when the flow rate is too high, heat loss will occur. Through activation treatment in the present invention, oxidants such as calcium peroxide (CaO 2 ), etc., act together with steam to be activated to generate strong oxidants such as hydroxyl radicals (·OH). These free radicals can effectively degrade organic pollutants in the soil; at the same time, the alkaline substances CaO and MgO in the contaminated soil and slag react with the water in the steam to form Ca(OH) 2 and Mg(OH) 2 , the pH value of the system is stabilized at 7~14, and the generated Ca(OH) 2 and Mg(OH) 2 provide conditions for the subsequent carbon fixation reaction. The chimney CO 2 reacts with alkaline substances to form stable carbonates, which not only realizes carbon capture but also solves the problem of the inhibition of the oxidation system by the alkaline environment. This process ensures the synergistic optimization of the removal of organic pollutants in the soil and carbon fixation by dynamically regulating the pH value.

[0039] As a specific embodiment of the present invention, waste gas containing carbon dioxide can be introduced from the bottom of the reaction tower. The waste gas containing carbon dioxide can be boiler flue gas. The volume concentration of carbon dioxide in the waste gas containing carbon dioxide can be 15 - 50%, can also be 20 - 40%, and can further be 30 - 38%. Before introducing the flue gas, the flue gas can also be subjected to dust removal treatment, and the dust obtained from the dust removal treatment can be mixed with the slag for use. As a specific embodiment of the present invention, the position where the waste gas containing carbon dioxide is introduced 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 CO 2 concentration (lower than 15%) may lead to low efficiency of carbonate formation, thereby reducing the carbon capture and carbon sequestration effect; too high CO 2 concentration (exceeding 50%) may cause the reaction rate to be too fast, leading to problems such as pipeline blockage. As a specific embodiment of the present invention, the flow rate of the waste gas containing carbon dioxide can be 1.0 - 2.0 L / min, can also be 1.2 - 1.7 L / min, and can further be 1.4 - 1.6 L / min; the time for introducing the waste gas containing carbon dioxide can be 2 - 4 h, can also be 2.5 - 3.5 h, and can further be 3 - 3.3 h.

[0040] As a specific embodiment of the present invention, during the carbon fixation process, CO 2 reacts with Ca(OH) 2 and Mg(OH) 2 formed in the packing to form stable carbonates (CaCO 3 、MgCO 3 ), which not only realizes carbon fixation but also dynamically adjusts the pH value of the system to the neutral range (6.5 - 8.5).

[0041] As a specific embodiment of the present invention, the pH value of the system after carbon fixation can be 7 - 10, can also be 8 - 9.

[0042] The treatment method provided by the present invention makes full use of the waste heat and water vapor resources of industrial boilers, recovers and applies steam and CO 2 to the pollution treatment process, realizing the efficient recycling of resources; the packing design combines the versatility of soil, CaO 2 and slag, which not only supports the degradation of pollutants but also enhances the efficiency of carbonate formation; the removal rate of benzene series compounds in the present invention is ≥90%, the removal rate of polycyclic aromatic hydrocarbons is ≥85%, and the formation rate of carbonates is ≥80%.

[0043] As a specific embodiment of the present invention, after carbon fixation, it further includes:

[0044] The tail gas after carbon fixation is recovered and condensed to obtain recovered water and recovered tail gas containing carbon dioxide respectively;

[0045] Water is collected at the bottom of the reaction tower.

[0046] Through recovery, the present invention can recycle all the unreacted carbon dioxide through the tail gas reflux pipeline; the water in the tail gas is fully extracted through the condenser, which is conducive to the recycling of water.

[0047] In the present invention, the discharged water contains organic matters and carbonates (calcium carbonate, magnesium carbonate).

[0048] The method provided by the present invention has remarkable steam waste heat utilization rate, pollutant removal rate and carbon fixation efficiency; in the present invention, the hot steam and flue gas in the boiler room are alternately blown into the reaction tower through two pipelines. The steam can provide sufficient heat and moisture to activate the advanced oxidation system (AOPs). In the liquid system, the catalyst (such as the iron element 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, generating more hydroxyl radicals (·OH), thereby decomposing organic pollutants such as benzene series and polycyclic aromatic hydrocarbons in the soil. Carbon dioxide (CO 2 )in the flue gas reacts with alkaline substances to form stable carbonates. In this process, CO 2 reacts with Ca(OH) 2 , Mg(OH) 2 and other substances from the soil to generate carbonates such as CaCO 3 , MgCO 3 and so on, which can achieve carbon capture and carbon fixation; by alternately introducing hot steam and flue gas, the present invention can not only maintain high-temperature conditions and sufficient moisture in the reaction tower to activate the advanced oxidation reaction, but also utilize the reaction of CO 2 with alkaline substances to adjust the salinization problem caused by the calcium peroxide product (calcium hydroxide), achieving an efficient cycle of pollutant removal and carbon fixation.

[0049] 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, including a reaction tower 1, a packing conveying unit 2 connected to the top inlet of the reaction tower 1, an exhaust gas conveying unit 3 containing carbon dioxide 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. As a specific embodiment of the present invention, a tree-shaped pipeline is arranged in the reaction tower, which is conducive to the uniform distribution of gases (steam, exhaust gas containing carbon dioxide), and can better contact with the packing (contaminated soil, slag, calcium peroxide) fully, improving the reaction efficiency.

[0050] As a specific embodiment of the present invention, the carbon dioxide-containing waste gas conveying unit 3 and the steam conveying unit 4 are connected in parallel to the reaction tower 1 through an air compressor.

[0051] 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 outlet collection unit connected to the bottom outlet of the reaction tower 1.

[0052] Figure 1 It is a schematic structural diagram of the system for the combined treatment method of contaminated soil and carbon emission reduction provided by the present invention, where 1 is the reaction tower, 2 is the filler conveying unit, 3 is the carbon dioxide-containing waste gas conveying unit, 4 is the steam conveying unit, and 5 is the air compressor.

[0053] Figure 2 It is a schematic process diagram for the combined treatment of contaminated soil and carbon emission reduction in the embodiment.

[0054] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0055] The embodiment is carried out according to Figure 2 the shown process to treat the contaminated soil and carbon dioxide in the flue gas.

[0056] Example 1

[0057] Around a certain petrochemical site, the soil is severely contaminated by benzene series substances. The benzene content in the contaminated soil is 95 mg / kg, and the following treatment is carried out using the repair method of the present invention:

[0058] First, filler preparation is carried out: the materials are contaminated soil with an average particle size of 2 mm, industrial-grade CaO with an active oxygen content of 18% and an average particle size of 200 μm 2 , industrial coal slag with an average particle size of 5 mm and a main component containing CaO, MgO and a small amount of Al 2 O 3 and Fe 2 O 3 ; the contaminated soil, CaO 2 and industrial coal slag are stirred and mixed in a mass ratio of 1:0.8:1 for 45 min and then loaded into the reaction tower as the lower filler (accounting for 37% of the total filler height); the contaminated soil and CaO 2 are stirred and mixed in a mass ratio of 1:0.5 for 40 min and then loaded into the reaction tower as the middle filler (accounting for 37% of the total filler height); the contaminated soil and CaO 2 are stirred and mixed in a mass ratio of 1:1.2 for 50 min and then loaded into the reaction tower as the upper filler (accounting for 26% of the total filler height); the total amount of filler in the reaction tower is 200 kg / m 3。

[0059] Inject steam into the coal stove. Inject steam at a temperature of 110 °C into the bottom of the reaction tower through a hollow ring-wall glass tube at a flow rate of 1.5 L / min, and continuously inject for 4 h for activation treatment; during this process, the heat and moisture of the steam activate the advanced oxidation system (AOPs), generating a large amount of hydroxyl radicals (·OH), effectively decomposing benzene series compounds in the soil. At the same time, the alkaline substances in the soil and slag react with water, causing the pH value of the system to rise.

[0060] After the steam oxidation is completed, the coal stove flue gas is dust-removed and then the flue gas with a stable CO 2 concentration maintained at 30% is injected into the bottom of the reaction tower through a hollow glass pipeline at a flow rate of 1.5 L / min for 3 h for carbon fixation; at this time, CO 2 rapidly reacts with Ca(OH) 2 and Mg(OH) 2 formed in the packing to efficiently form stable carbonates (CaCO 3 and MgCO 3 ), realizing carbon fixation and accurately adjusting the pH value of the system to 7.5.

[0061] In the tail gas treatment stage, the unreacted CO 2 is fully recycled through the tail gas reflux pipeline, and the remaining tail gas is used to fully extract moisture through a condenser.

[0062] Finally, collect the treated water sample from the bottom of the reaction tower for detection. The removal rate of benzene series compounds reaches 93%, the removal rate of polycyclic aromatic hydrocarbons reaches 88%, and the carbonate formation rate is 89%. Through XRD analysis, the main crystal forms of the carbonate products are calcite (CaCO 3 ) and magnesite (MgCO 3 ), and their characteristic peaks clearly appear at 29.4° (CaCO 3 ) and 42.9° (MgCO 3 ) respectively.

[0063] Example 2

[0064] In an industrial waste site, the content of benzene in the contaminated soil is 12 mg / kg.

[0065] Load the packing according to the method of Example 1, the difference is that the active oxygen content of CaO 2 is 19%, the average particle size of the contaminated soil is 1.8 mm, and the average particle size of the slag is 3 mm (the main components include CaO, MgO and a small amount of Al 2 O 3 and Fe 2 O 3), the total amount of packing is determined to be 230 kg / m based on the volume of the reaction tower 3 ; The stirring time for mixing the materials is 50 min.

[0066] Inject the steam from the coal stove at a temperature of 105 °C into the bottom of the reaction tower at a flow rate of 2.0 L / min for 5 h for activation treatment to activate the decomposition of pollutants by AOPs, causing the pH value of the system to rise; Subsequently, after dust removal treatment of the coal stove flue gas, the flue gas with a CO 2 concentration of 40% is injected into the bottom of the reaction tower at a flow rate of 1.2 L / min for carbon fixation, and the injection time is 3.5 h, reacting with the generated alkaline substances to achieve carbon fixation and pH value adjustment.

[0067] Perform tail gas recovery, water extraction, and effluent collection according to the method of Example 1. After detection, the removal rate of benzene series compounds in the water sample (effluent) reaches 90%, the removal rate of polycyclic aromatic hydrocarbons reaches 86%, and the carbonate generation rate is 84%. The crystal form and characteristic peaks of the products detected by XRD are consistent with those of Example 1, indicating that the present invention can effectively remove pollutants and achieve a certain degree of carbon fixation in different pollution scenarios, verifying its feasibility and effectiveness.

[0068] Example 3

[0069] In a polluted site in the shutdown area of a petrochemical plant, the soil is complexly polluted, with the benzene content being 17 mg / kg, the naphthalene content being 11 mg / kg, and accompanied by heavy metals lead (Pb) content of 0.6 mg / kg and mercury (Hg) content of 0.08 mg / kg.

[0070] Prepare the packing: Load the packing according to the method of Example 1. The difference is that the packing is polluted soil with an average particle size of 1.8 mm, industrial-grade CaO with an active oxygen content of 21% and a particle size in the range of 120 - 260 μm 2 、slag from industrial waste furnaces with a particle size not exceeding 4 mm and mainly composed of CaO, MgO, and a small amount of Al 2 O 3 and Fe 2 O 3 Stir for 58 min in a planetary mixer when mixing the materials.

[0071] Then, inject the steam from the coal stove at a temperature of 115 °C into the bottom of the reaction tower through a hollow ring-wall glass tube at a flow rate of 1.9 L / min for activation treatment, and continuously inject for 4.8 h; The steam activates the advanced oxidation system (AOPs) to generate a large amount of hydroxyl radicals (·OH) to decompose organic pollutants, and the alkaline substances in the soil and slag react with water to cause the pH value of the system to rise; After steam oxidation, after dust removal treatment of the coal stove flue gas, the CO 2The preliminarily purified flue gas with a concentration of 38% is injected into the reaction tower from the bottom through a hollow glass pipeline at a flow rate of 1.7 L / min for 3.6 h for carbon fixation, and CO 2 reacts with the generated Ca(OH) 2 and Mg(OH) 2 to form carbonates to achieve carbon fixation and adjust the pH value to 7.9.

[0072] In the tail gas treatment stage, the unreacted CO 2 is completely recycled through the tail gas reflux pipeline, and the remaining tail gas is fully extracted of moisture through a condenser.

[0073] Finally, the water sample at the bottom of the reaction tower is detected. The removal rate of benzene series is 94%, the removal rate of naphthalene is 90%, and the carbonate formation rate is 91%. XRD analysis shows that the main crystal forms of the products are calcite (CaCO 3 ) and magnesite (MgCO 3 ), and the characteristic peaks appear at 29.4° (CaCO 3 ) and 42.9° (MgCO 3 ) respectively. The content of lead (Pb) in the treated soil drops to 0.15 mg / kg, and the content of mercury (Hg) drops to 0.02 mg / kg.

[0074] Example 4

[0075] At a site where a chemical leakage accident occurred and the subsequent cleanup was not thorough, the soil pollution shows high complexity. The benzene content in the soil is 17 mg / kg, the toluene content is 13 mg / kg, the pyrene content is 11 mg / kg, the benzo[a]pyrene content is 7 mg / kg, and at the same time, the heavy metal cadmium (Cd) content is 0.6 mg / kg and the chromium (Cr) content is 0.4 mg / kg.

[0076] The packing is loaded according to the method of Example 1, except that the packing is contaminated soil with an average particle size of 1.6 mm, industrial-grade CaO with an active oxygen content of 21% and a particle size in the range of 120 - 280 μm 2 , furnace slag of industrial waste residue with a particle size not exceeding 4 mm and the main components including CaO, MgO and a small amount of Al 2 O 3 and Fe 2 O 3 . When mixing the mixed materials, stir in a high-strength mixer for 52 min.

[0077] Next, coal furnace steam at a temperature of 100 °C is injected upward from the bottom of the reaction tower through a hollow ring-wall glass tube at a flow rate of 1.6 L / min for activation treatment for 4.6 h. The heat and moisture of the steam activate the advanced oxidation system (AOPs) to decompose benzene series compounds and polycyclic aromatic hydrocarbons in the soil. At the same time, the alkaline substances in the soil and slag react with water, and the pH value of the system rises.

[0078] After the steam oxidation is completed, the coal furnace flue gas is dust-removed, and then the flue gas with a CO 2 concentration stably maintained at 35% after preliminary purification treatment is injected from the bottom of the reaction tower through a highly sealed hollow glass pipeline at a flow rate of 1.7 L / min for carbon fixation for 3.4 h to achieve carbon fixation and adjust the pH value of the system to 7.8.

[0079] In the tail gas treatment stage, the unreacted CO 2 is fully recycled by using a reflux pipeline, and the remaining tail gas is used to fully extract moisture by using a condenser.

[0080] Finally, the treated effluent water sample is collected from the bottom of the reaction tower for detection. The removal rate of benzene series compounds reaches 94%, the removal rate of polycyclic aromatic hydrocarbons reaches 91%, and the carbonate formation rate is 90%. Through XRD analysis, the main crystal forms of the carbonate products are calcite (CaCO 3 3) and magnesite (MgCO 3 3), and their characteristic peaks clearly appear at 29.4° (CaCO 3 3) and 42.9° (MgCO 3 3), further highlighting the excellent performance of the present invention in treating complex polluted sites, especially the outstanding effect in the face of multiple organic pollutants and heavy metal combined pollution.

[0081] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments according to these embodiments without creative efforts, and these embodiments all belong to 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 contaminated soil includes contaminated soil from a petrochemical site, and the average particle size of the contaminated soil is ≤2mm; the slag includes slag from a steel plant, and the average particle size of the slag is ≤5mm; the purity of the calcium peroxide is 30-60%, the active oxygen content is ≥18%, and the average particle size is 100-300μm; The filler in the reaction tower filled with the filler is activated to decompose the organic pollutants in the contaminated soil, and then the waste gas containing carbon dioxide is introduced to fix carbon, thereby obtaining purified soil and purified waste gas respectively; the activation treatment method includes introducing steam into the reaction tower; the organic pollutants include benzene series and / or polycyclic aromatic hydrocarbons; 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; 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; The mass ratio of contaminated soil to calcium peroxide in the second mixture of contaminated soil and calcium peroxide is 1:1-1.5; 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.

2. 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.

3. 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.

4. 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.

5. The system used in the combined treatment method for contaminated soil and carbon emission reduction according to any one of claims 1 to 4 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).

6. The system according to claim 5, 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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