JP2005279423A - Method for in situ purification of contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable in situ purification by enhancing a recovery efficiency of an organic contaminated substance (particularly, oils) in a contaminated area in a geologic stratum. <P>SOLUTION: A method for in situ purification of contaminated soil includes a process for injecting a mixed liquid of a detergent and a solvent, and water into the contaminated area 12 in the geologic stratum caused by the organic contaminated substance to mix with the organic contaminated substance present in the geologic stratum, thereby preparing an emulsified liquid having a low viscosity by an emulsification/release action; and a process for injecting a foaming agent to promote mixing and emulsification by a foaming action in the geologic stratum, wherein the emulsified liquid decreasing a viscosity is sucked to recover on the ground. A process for diluting the emulsified liquid by the continuous passage of water and sucking to recover on the ground, or a process for injecting water containing an activated carbon, adsorbing the emulsified liquid left in the geologic stratum on an activated carbon particle and sucking to recover on the ground may be incorporated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for in situ purification of in-situ contamination with organic pollutants, particularly oils. More specifically, the present invention injects a mixture of a surfactant and a solvent and water to bring it into contact with organic pollutants present in the formation, and injects a foaming agent to mix by microfoaming in the formation. The present invention relates to an in-situ purification method for contaminated soil that promotes emulsification and lowers the viscosity of the resulting emulsified liquid to increase fluidity and suck and collect it.

  In recent years, soil and groundwater contamination due to oil leaks has become serious in factories and gas station sites all over the country. Although the leaked oil is dissolved to some extent in the groundwater, most of the oil remains in the formation in the state of a stock solution. From the viewpoint of reuse of land and prevention of expansion of groundwater pollution, purification of the strata by collecting contaminated oil is required.

  Conventionally, there is a pumping method as a method for cleaning soil and groundwater contaminated with oils in situ. This is a method of installing a pumping well to lower the surrounding groundwater level, guiding oil into the well, and collecting the contaminated oil with a pumping device such as an oil skimmer pump. However, due to the viscosity of oils and the action of adsorbing to soil particles, oils do not collect in wells when the groundwater level decreases due to pumping. In other words, the oil does not flow into the water under the action of the water gradient, and therefore does not flow into the well. Therefore, in such a conventional method, it is the actual situation that only water is pumped up and oils cannot be recovered.

Therefore, in order to improve the oil recovery efficiency, a method has been proposed in which water is pumped up and recovered from the wells mixed with chemicals (cleaning agents) for cleaning the oil in the groundwater outside the permeation range of the oil. (For example, refer to Patent Document 1). However, in a large soil tank experiment conducted by the present inventors, the neutral detergent aqueous solution was administered to the oil-contaminated soil and pumped up, and the oil adhering to the soil particles was simply added by adding the neutral detergent aqueous solution. It turns out that even the oil present in the gap can hardly be moved. In other words, oils in the immediate vicinity of the well can be pumped together with water, but only water is pumped after that, and the recovery efficiency is very low. When the oil is no longer pumped up, it is determined that the collection is complete, and then when the ground is dug up and surveyed, it is found that most of the oil remains in the formation.
JP-A-1-95191

  The problem to be solved by the present invention is that the conventional technology has very poor recovery efficiency of organic pollutants (especially oils) in the contaminated area in the formation.

  The present invention pays attention to the fact that oil and oil do not flow only by the action of the hydrodynamic gradient (does not ride on the flow of water) because water and oil are in separate phases. In addition to making it a single phase, the emulsion obtained at that time is made to have a low viscosity, and mixing and emulsification in micro gaps are promoted by utilizing the micro-foaming action in the formation to improve fluidity. It has been devised to make it easier to suck and collect on the ground.

  That is, the present invention injects a mixture of a surfactant and a solvent and water into an area contaminated with organic pollutants and mixes it with organic pollutants present in the formation, and has low viscosity due to emulsification and peeling action. It comprises a step of generating an emulsion and a step of injecting a foaming agent to promote mixing and emulsification by a fine foaming action in the formation, and the emulsion that has been reduced in viscosity is sucked to the ground and recovered. In-situ purification method for contaminated soil. Organic pollutants to be purified in the present invention are mainly mineral oils such as crude oil, gasoline, kerosene, heavy oil, machine oil, cutting oil, coolant oil, and other hydrocarbon compounds such as trichlorethylene and creosote Is also included.

  Here, it is effective to inject the mixed liquid of the surfactant and the solvent and water in a stepwise manner so that the ratio of the mixed liquid is high at the beginning and the ratio of water is increased later. It is. It is effective to perform a plurality of cycles by combining the steps of injecting the foaming agent. The solvent serves to dilute the surfactant, and for example, ethanol is used. Moreover, it is preferable to start foaming when the foaming agent and the foaming aid are separately injected from the ground so as to foam in the formation and mixed in the ground. For example, sodium bicarbonate water is used as a foaming agent, and acetic acid is used as a foaming aid. When sodium bicarbonate water is injected and acetic acid (in this specification, “acetic acid” is an aqueous solution of acetic acid) is injected after reaching the formation, the reaction proceeds throughout the formation and a micro-foaming phenomenon occurs. Moreover, the process of diluting an emulsion liquid by continuous water flow and sucking it on the ground and collecting it is appropriately incorporated. It is also effective to incorporate a step of injecting activated carbon-containing water (particularly during foaming), adsorbing the emulsion remaining in the formation to the activated carbon particles, and sucking and collecting the emulsion.

  The surfactant used in the present invention is a mixture of one or more selected from nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants, and is suitable for harmful pollutants. Select what you did. It is preferable that the HLB of the surfactant in which one kind or two or more kinds are mixed is 5 to 12. The solvent used is a mixture of one or more selected from solvents having a solubility in water at 20 ° C. of 1% by weight or more. The mixing ratio of the surfactant and the solvent is 5 to 95% by weight: 95 to 5% by weight.

  For liquid injection into the formation, for example, a horizontal spray nozzle that sprays a mist-like liquid uniformly over the entire circumference in the horizontal direction and a reverse spray nozzle that sprays a mist-like liquid evenly over the entire circumference in an obliquely upward direction are used. It is preferable to do this. Insert them into the injection well protected by the hole wall with slit screen, horizontal injection nozzle from the same level as the contaminated area in the formation, and from the lower level than the contaminated area in the reverse injection nozzle formation at any multiple depths A mist-like liquid is injected under pressure. During the purification work, a number of wells are distributed in the target stratum, and the contaminated areas in the strata are identified, and a part of the wells in the contaminated area are used for liquid injection, and at least a part of the other is recovered in the emulsion. The well outside the contaminated area will be used for monitoring the pollution diffusion.

  The emulsion recovered on the ground promotes oil-water separation by natural standing or physical or chemical treatment, and the water layer portion is treated by biological treatment, and the oil layer portion is treated by incineration or the like. Regarding biological treatment of water layer parts containing unseparated oil, solid-liquid separation after treatment is carried out by precipitation, flotation or membrane separation, and when the separated sludge is returned to the aeration tank, oil that is not biologically treated is removed. Continuous operation or batch operation can be performed by drawing out with excess sludge.

  The in-situ purification method for contaminated soil of the present invention is a method of injecting a mixture of a surfactant and a solvent and water and mixing it with an organic contaminant present in the formation, Since it has a step of generating and a step of injecting a foaming agent and promoting mixing and emulsification by the fine foaming action in the formation, the emulsion can be made to have a low viscosity, improve fluidity, and can be mixed evenly. Therefore, by sucking the emulsified liquid on the ground, organic pollutants (especially oils) in the contaminated area in the formation can be efficiently recovered.

  The emulsion remaining in the formation can be recovered more effectively by appropriately combining the dilution of the emulsion by continuous water flow or the adsorption of the emulsion to the activated carbon particles by the injection of activated carbon-containing water. It becomes possible to do.

  If a horizontal injection nozzle that injects a mist-like liquid uniformly over the entire circumference in the horizontal direction and a reverse injection nozzle that injects a mist-like liquid uniformly over the entire circumference in an obliquely upward direction, even with one injection well, any It becomes possible to inject liquid under different directions at a plurality of depths. In particular, the use of the horizontal injection nozzle at a level level with respect to the contaminated area and the reverse injection nozzle at a level below the contaminated area facilitates oil detachment and emulsification.

  The work procedure of the in-situ purification method for contaminated soil according to the present invention is shown in FIG. If contamination by oil is found and needs to be removed and collected, a survey is first conducted to identify the contaminated area. As shown in a plan view in FIG. 2, a number of wells (indicated by circles) are dispersed around the underground tank 10 (for example, in a grid pattern with a pitch of 3 to 10 m). The well 12 is excavated and observed to the extent that contamination cannot be confirmed, and the contaminated area 12 is specified. At least a part of the well provided inside the contaminated area 12 is a countermeasure injection well. The remaining wells may be pumped oil (emulsified liquid) recovery wells, or a pumped oil recovery well (indicated by Δ) may be excavated separately. Wells outside the contaminated area will be used to monitor the spread of contamination during the process. An example of the xx cross section in FIG. 2 is schematically shown in FIG. Once the contaminated area is identified, a chemical and water injection facility for purification and a pumping oil recovery facility will be installed on the ground. Then, the injection / recovery operation is performed.

  FIG. 4 schematically shows the purification method of the present invention. A mixture of a surfactant and a solvent and water are injected from an injection facility on the ground through the injection pipe 20 into the contaminated area in the formation with oil, mixed with the oil (contaminant) present in the formation, and emulsified. -A low-viscosity emulsion is produced by the peeling action. Moreover, a foaming agent is inject | poured through the injection pipe 20 in the injection well 14 from the injection | pouring equipment on the ground, and mixing and emulsification are accelerated | stimulated by the fine foaming effect | action in a formation. The emulsified liquid whose viscosity has been reduced in this manner is sucked and collected by the ground collecting equipment through the suction pipe 22 in the collecting well 16. If necessary, dilute the emulsion by continuous water flow, or inject the activated carbon-containing water while foaming continues to adsorb the emulsion remaining in the formation to the activated carbon particles, and suck and collect them on the ground. .

  A process of injecting a mixture of surfactant and solvent and water and mixing with oils to produce a low-viscosity emulsion by emulsification / peeling action, and a foaming agent to inject fine foam in the formation The step of promoting mixing and emulsification may be repeated as necessary. The process of diluting the emulsion by continuous water flow and sucking it to the ground and collecting it, and injecting the activated carbon-containing water while foaming continues to adsorb the emulsion remaining in the formation to the activated carbon particles and sucking them to the ground The recovering steps may be incorporated into them in any order.

  As the surfactant, an optimum one that can exhibit an emulsification phenomenon and separation performance is selected by preliminary experiments according to the type of oil that is a contaminant, and the blending ratio with the solvent is adjusted. As the solvent, for example, ethanol is used. The solvent serves to dilute the surfactant, thereby fulfilling the function of reducing the viscosity of the emulsion and increasing the fluidity. As described above, the foaming agent and the foaming aid are, for example, a combination of sodium bicarbonate water and acetic acid, and are injected into the formation after a certain time. Baking soda may be mixed with water when a mixture of a surfactant and a solvent and water are injected. The emulsified liquid collected by suction promotes oil / water separation by natural standing or physical or chemical treatment, and the water layer portion is treated by biological treatment, and the oil layer portion is treated by incineration or the like.

  FIG. 5 is a process explanatory view showing an embodiment of the in-situ purification method for oil-contaminated soil according to the present invention. As shown in A, a liquid injection facility 24 and an emulsion (oil / water mixture) recovery facility 26 are installed on the ground. In addition, various liquids can be injected into the well provided in or near the contaminated area using the injection pipe 20, and the emulsified liquid or the like can be sucked and collected from another well in the contaminated area through the suction pipe 22. To do.

  First, as shown in B, a mixed liquid of a surfactant and a solvent (ethanol) suitable for emulsification of contaminated oil is prepared at a desired blending ratio, and is injected into the formation through the injection pipe 20 from the injection equipment together with water. . These liquids come into contact with the contaminated oil stock solution in the contaminated area and emulsify them. At this time, the emulsion is recovered by suction from the suction tube 22 by a suction recovery facility. However, sufficient emulsification is difficult only by this process, and as shown in C, the contaminated area is a mixed portion where the oil remains as a whole, and the oil stock remains locally.

  Therefore, as shown in D, a foaming agent is injected. As shown, the suction tube is preferably switched to the injection tube and injected over substantially the entire contaminated area. Here, sodium bicarbonate water is injected first, and then acetic acid is injected after a period of time. Baking soda water reaches almost the entire contaminated area, and then reacts with acetic acid when it comes into contact. By this (sodium bicarbonate + acetic acid) reaction, fine foaming occurs in the entire contaminated area, thereby promoting the mixing / emulsification of the mixed liquid (surfactant + solvent) and oil injected.

  If the emulsification is considered insufficient due to severe contamination or due to the formation conditions of the strata and wells, the above steps may be repeated one or more times. That is, the step of injecting the mixed liquid (surfactant + solvent) and water and the step of injecting the foaming agent are repeated as many times as necessary. In this case, it is preferable that the concentration of the mixed solution with respect to water is initially set to be high, and the concentration is changed step by step so that the amount of water is increased in later steps.

  Then, as indicated by E, water is continuously passed through the injection tube 20, and the liquid (emulsified liquid + water) is sucked and collected from the suction tube 22. This is a so-called “rinse” process. As a result, the emulsion is diluted and almost recovered.

  However, depending on the state of the formation and the arrangement of the wells, as shown in F, it is expected that the emulsified liquid will remain on the soil particles because it is difficult to remove. Therefore, in order to further enhance the removal effect, as shown in G, water containing activated carbon powder is injected from the injection tube 20. As a result, the emulsifier remaining in the formation is adsorbed on the activated carbon particles and sucked and collected together with water. In this way, as indicated by H, it is possible to realize a state in which the oil and the emulsifier are almost completely removed.

  A horizontal spray nozzle or a reverse spray nozzle is preferably used for injecting the liquid into the formation. As shown in FIG. 6A, the horizontal injection nozzle 30 has a structure in which about 6 to 10 minute openings 32 are formed over the entire circumference in the horizontal direction, and the mist is evenly distributed over almost the entire circumference in the horizontal direction. The liquid is jetted in the shape of As shown in FIG. 6B, the reverse injection nozzle 34 has a structure in which about 6 to 10 minute openings 36 are formed over the entire circumference of the diagonally rearward direction, and substantially all of the diagonally rearward (and hence diagonally upward). The liquid is sprayed uniformly in the form of a mist over the circumference.

  Using these nozzles, as shown in FIG. 7, the liquid is injected by inserting into the same injection well where the hole wall is protected by the slit screen 38 at different depths. In that case, the horizontal injection nozzle 30 is positioned laterally of the contaminated area, and the reverse injection nozzle 34 is positioned below the contaminated area to perform liquid injection. By selecting the nozzle and changing the installation position in this way, it becomes possible to inject liquid uniformly from various directions and positions with respect to the contaminated area.

  The recovered emulsified liquid promotes oil / water separation by natural standing or physical or chemical treatment, and the water layer portion is treated by biological treatment, and the oil layer portion is treated by incineration or the like. Regarding biological treatment of water layer parts containing unseparated oil, solid-liquid separation after treatment is carried out by precipitation, flotation or membrane separation, and when the separated sludge is returned to the aeration tank, oil that is not biologically treated is removed. Continuous operation or batch operation is performed by drawing out with excess sludge. Oil-containing wastewater usually floats and separates oil by a pressure flotation method, etc., but in the above examples, water containing sodium bicarbonate is sucked and collected. It is possible to float and separate by generating bubbles and attaching these bubbles to the oil. In addition, the oil component that has not been completely separated and has been used for biological treatment can be taken out of the system together with the excess sludge by adhering to the activated sludge.

  The surfactant used in the present invention is a mixture of one or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

  As the nonionic surfactant, polyoxyalkylene nonionic surfactants, polyhydric alcohol fatty acid ester nonionic surfactants, fatty acid alkanolamides, polyoxyalkylene fatty acid alkanolamides, alkyl glucosides, and the like can be used. Examples of the polyoxyalkylene nonionic surfactant include polyoxyalkylene alkyl (or alkenyl) ether, polyoxyalkylene alkyl (or alkenyl) phenyl ether, polyoxyalkylene alkyl (or alkenyl) ester, polyoxyalkylene glycerin fatty acid ester, polyoxyalkylene alkyl (or alkenyl) ether Oxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkyl (or alkenyl) amine, polyoxyethylene-polyoxypropylene copolymer (block or random copolymer), polyoxyalkylene castor oil ether, polyoxyalkylene hardened castor oil ether, polyoxy Examples include alkylene alkyl (or alkenyl) ester alkoxylates. As the alkyl group and alkenyl group in the compounds exemplified as the polyoxyalkylene nonionic surfactant, those having 8 to 22 carbon atoms, particularly those having 12 to 18 carbon atoms are preferable. Examples of the polyoxyalkylene group include a polyoxyethylene group, a polyoxypropylene group, a polyoxyethylene-polyoxypropylene group (block or random copolymer), and the like.

As the polyhydric alcohol fatty acid ester nonionic surfactant, either a partial ester or a complete ester of a polyhydric alcohol and a fatty acid can be used. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, trimethylolpropane, glycerin, diglycerin, triglycerin, pentaerythritol, sorbitol and the like. Is mentioned. More specific examples of polyhydric alcohol fatty acid esters include ethylene glycol monooleate, propylene glycol monolaurate, trimethylolpropane monopalmitate, pentaerythritol monomyristate, sorbitol monooleate, glycerin monoolein Acid ester, glycerol dioleate, glycerol trioleate, etc. are mentioned. Among the polyhydric alcohol fatty acid esters, monoesters and diesters of polyethylene glycol, glycerin, sorbitol and C _{12 to} C ₁₈ saturated or unsaturated fatty acids are preferable. Among fatty acid alkanolamides, diethanolamides of C _{12 to} C ₁₈ saturated or unsaturated fatty acids are preferred. Of the polyoxyalkylene fatty acid alkanolamides, monoethanolamides and diethanolamides of C _{12 to} C ₁₈ saturated or unsaturated fatty acids are preferred. Examples of the polyoxyalkylene groups include polyoxyethylene groups, polyoxypropylene groups, and polyoxyalkylenes. An ethylene-polyoxypropylene group (block or random copolymer) and the like can be mentioned. Moreover, as an alkyl group in alkyl glucoside, a C10-C12 thing is preferable. In this invention, a nonionic surfactant can be used 1 type or in mixture of 2 or more types.

  Examples of the anionic surfactant include salts of fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, alkyl (or alkenyl) sulfate esters, and alkyl (or alkenyl) sulfates. Alkyl (or alkenyl) benzene sulfate, polyoxyalkylene alkyl (or alkenyl) ether sulfate, polyoxyalkylene alkyl (or alkenyl) ether phosphate, polyoxyalkylene alkyl (or alkenyl) phenyl ether sulfate, Examples include α-olefin sulfate, castor oil sulfate ester, sodium dialkyl (or dialkenyl) sulfosuccinate and the like. Examples of the salt include sodium salt, potassium salt, ammonium salt, alkanolamine salt and the like.

  Alkyl (or alkenyl) sulfate, alkyl (or alkenyl) sulfate, alkyl (or alkenyl) benzene sulfate, polyoxyalkylene alkyl (or alkenyl) ether sulfate, polyoxyalkylene alkyl (or alkenyl) ether As alkyl groups and alkenyl groups in phosphoric acid ester salts, polyoxyalkylene alkyl (or alkenyl) phenyl ether sulfate salts, α-olefin sulfate salts, sodium dialkyl (or dialkenyl) sulfosuccinates, etc., those having 8 to 22 carbon atoms In particular, those of 12 to 18 are preferred. Examples of the polyoxyalkylene group include a polyoxyethylene group, a polyoxypropylene group, a polyoxyethylene-polyoxypropylene group (block or random copolymerization), and the like. In the present invention, the anionic surfactant can be used alone or in combination of two or more.

  Examples of the cationic surfactant include alkyl (or alkenyl) dimethylamine oxide, alkyl (or alkenyl) trimethyl ammonium halide, dialkyl (or alkenyl) dimethyl ammonium halide, alkyl (or alkenyl) pyridinium halide, and the like. Examples of the halogen in the halide compound include chlorine and bromine. As the alkyl group and alkenyl group in the compounds exemplified as the cationic surfactant, those having 8 to 18 carbon atoms, particularly those having 12 to 16 carbon atoms are preferable. In the present invention, the cationic surfactant can be used alone or in combination of two or more.

  Amphoteric surfactants include alkyl (or alkenyl) betaines, alkyl (or alkenyl) dimethylaminoacetic acid betaines, alkyl (or alkenyl) amidopropyl betaines, 2-alkyl (or alkenyl) -N-carboxymethyl-N-hydroxyethyl. Examples include imidazolinium betaine and alkaloylmethyl-β-alanine. As the alkyl group and alkenyl group in the compounds exemplified as the amphoteric surfactant, those having 8 to 22 carbon atoms, particularly those having 12 to 18 carbon atoms are preferable. In the present invention, amphoteric surfactants can be used alone or in combination of two or more.

  In the present invention, a surfactant obtained by mixing one or two or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants is used, and the HLB of the surfactant is 5 It is preferably ~ 12. If the surfactant HLB is less than 5, it is difficult to dissolve in water, and the affinity with the hydrocarbon compound that is the source of contamination increases, so it tends to remain in the soil together with the hydrocarbon compound, thereby purifying the contaminated soil. It becomes difficult. When the HLB of the surfactant exceeds 12, the affinity with the hydrocarbon compound that is the source of contamination is reduced, so that the hydrocarbon compound cannot be sufficiently emulsified, and it becomes difficult to purify the contaminated soil.

In the present invention, the HLB of the polyoxyalkylene nonionic surfactant refers to the value obtained from the following formula (1), and the HLB of the polyhydric alcohol fatty acid ester nonionic surfactant is a value obtained from the following formula (2). Say. Moreover, HLB of fatty acid alkanolamide and polyoxyalkylene fatty acid alkanolamide refers to a value obtained from the following formula (3). The HLB of the alkyl glucoside is 13 and the HLB of the anionic surfactant, cationic surfactant and amphoteric surfactant is 20. Moreover, HLB at the time of mixing 2 or more types of surfactant says the value calculated | required from following (4) Formula.
HLB = (AO ÷ NS) × 20 (1)
HLB = (PA ÷ NS) × 20 (2)
HLB = {(AO + AL) ÷ NS} × 20 (3)
AO: molecular weight of alkylene oxide PA: molecular weight of polyhydric alcohol AL: molecular weight of alkanol × number of alkanol × 2
NS: Molecular weight of nonionic surfactant HLB = (A × a + B × b + C × c +...) ÷ 100 (4)
A: HLB of surfactant A, a: Mixing ratio (%) of surfactant A
B: HLB of surfactant B, b: Mixing ratio of surfactant B (%)
C: HLB of surfactant C, c: Mixing ratio of surfactant C (%)
a + b + c +... = 100

  The solvent used in the present invention is preferably a solvent having a solubility in water at 20 ° C. of 1% by weight or more. Such solvents include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, 2-butanol, 3-butanol, 1-pentanol, 3-methyl-1-butanol, 2-pentanol, 4- Alcohol solvents such as methyl-2-pentanol, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ketone solvents such as acetone, methyl acetone, methyl ethyl ketone, acetonyl acetone, diacetone alcohol, methyl acetate, ethyl acetate, Esters such as n-propyl acetate, isopropyl acetate, methoxybutyl acetate, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoe Ether, ethylene glycol diethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether, methoxyethoxyethanol, ethylene glycol monoacetate, ethylene glycol diacetate, Diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl Ether, diethylene glycol dimethyl ether, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether Glycol solvents such as 1-butoxyethoxyethanol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, , 5-pentanediol, hexylene diol Call, octylene glycol, glycerin, glyceryl monoacetate, glyceryl diacetate, glyceryl triacetate, trimethylolpropane, 1,2,6-hexane polyhydric alcohol solvents triol such as tetrahydrofuran and the like. Among the above solvents, alcohol solvents are particularly preferable. In the present invention, the solvent having a solubility in water at 20 ° C. of 1% by weight or more can be used alone or in combination of two or more.

  The solvent used in the present invention preferably has a solubility in water at 20 ° C. of 1% by weight or more. Among them, the solubility in water is particularly preferably 10% by weight or more. If the solubility in water is less than 1% by weight, it cannot be diluted with water, so that the solvent may remain in the soil and contaminate the soil.

  The mixing ratio of the surfactant and the solvent used in the present invention is preferably 5 to 95% by weight: 95 to 5% by weight. If the surfactant is less than 5% by weight, it is difficult to sufficiently emulsify the hydrocarbon compound which is a pollution source, and it becomes difficult to purify the contaminated soil. Further, if the solvent is less than 5% by weight, the viscosity of the emulsion produced by the surfactant does not decrease, so that it becomes difficult to move in the soil, and it becomes difficult to recover the pumped water.

  In the following, basic experiments conducted to support the effectiveness of the present invention will be outlined.

(Experimental example 1)
Previous studies have confirmed that the washing efficiency is improved by emulsification, but the viscosity of the liquid immediately after emulsification is so high that the fluidity in the ground is significantly reduced. It was. In order to solve this problem, these steps were conceived by (a) diluting the surfactant with ethanol (solvent) and (b) promoting mixing using the foaming action of sodium bicarbonate and acetic acid. Was examined.

A column experimental apparatus as shown in FIG. As a soil sample, Toyoura sand (the gap is smaller than mountain sand and the oil does not easily move) is mixed uniformly with 300 g Toyoura sand and 30 g oil to make oil-contaminated soil, and this is placed in a transparent column 40 made of acrylic resin. Filled. Then, the liquid was administered from above, and the emulsified liquid was sucked from the bottom by the vacuum pump 42. The oil was previously colored red with a colorant (Zudan IV) to facilitate observation of oil movement. According to several liquid dosing processes, the liquid was administered every 5 minutes. as a result,
The liquid dosing process of (1) surfactant (HLB 6.39 polyoxyethylene (10) hydrogenated castor oil ether) + ethanol (2) aqueous sodium bicarbonate (3) acetic acid (4) water was the best. In this liquid dosing process,
(1) When the surfactant and ethanol were administered, the oil and the surfactant changed to a familiar state.
(2) When sodium bicarbonate water was administered, it reacted with water and emulsified. Furthermore,
(3) By administering acetic acid water, it reacted with baking soda to cause a foaming action and promote mixing and emulsification.
(4) The oil could be completely removed by repeating dilution (rinsing) with water.
A comparison between before and after the experiment confirmed that no oil remained in the soil sample.

  Since the above-mentioned column experiment solved the problem regarding the fluidity of the emulsion, an experiment for confirming the flow of the emulsion was conducted using a tabletop water tank in order to bring it closer to the actual ground. An experimental apparatus using a tabletop water tank is shown in FIG. The water tank 44 has a width of 29 cm, a depth of 17 cm, and a depth of 17 cm. In order to prevent clogging of the soil particles due to suction, the suction hole at the lower end of the suction pipe 48 was covered with a cloth bag 46 containing glass beads (particle diameter 1.0 mm). Dry Toyoura sand (layer thickness 12 cm) and oil-contaminated soil (layer thickness 2 cm) uniformly mixed with oil were filled, and the liquid was administered according to the liquid administration process described above. The suction by the vacuum pump 42 was performed from the bottom of Toyoura sand, and the movement when the oil became an emulsified liquid was confirmed. In this experiment, the above liquid administration process was performed for two cycles.

  First cycle: Liquid was administered to the oil-contaminated soil according to the liquid administration process. It was confirmed that the emulsified liquid floated from the entire surface due to the foaming action of the reaction between sodium bicarbonate and acetic acid. In the previous air pressure insertion experiment, there was a problem of uneven cleaning only at 2 to 3 places, but this foaming solved the problem of unevenness. However, residual oil was still found on the side of the tank. Therefore, it shifted to the second cycle for further purification.

  Second cycle: The soil sample in the water tank was compacted due to the suction of the vacuum pump in the first cycle. Therefore, in the second cycle, sodium bicarbonate water and acetic acid were first administered, and the soil sample was once foamed and remained. The oil was made easy to move. Again, water was administered and dilution (rinsing) was repeated several times to confirm that the emulsion was no longer recovered, and the experiment was terminated. After the experiment was completed, the surface layer of the soil sample was excavated to confirm the residual state of the oil. As a result, no oil remained on the ground surface or in the soil.

  In the previous emulsification experiment using only the surfactant, once a highly viscous part appears in the ground due to some change in the situation, the viscosity of this part could not be lowered thereafter. However, using the liquid administration process established this time, it was found that the purification operation can be continued for several cycles as in the above experiment.

  Based on this tabletop water tank experiment, we conducted a small two-dimensional soil tank experiment in the next chapter in order to confirm the extent to which the contaminated oil can be purified and recovered even when the experimental scale is further increased. Using the administration process established in this way, the purification effect in a state closer to the actual ground was confirmed in a small two-dimensional soil tank experiment. An experimental apparatus as shown in FIG. 10 was assembled. In this experiment, the suction hole 50 was separated from the oil-contaminated area by 25 cm, and the movement of the emulsion was visually observed. The earthen tank 52 was 69 cm wide × 13 cm deep × 80 cm high. The soil sample 54 was Toyoura sand, moistened with water, and mixed with 1500 ml of oil.

The administration process is as follows. The first cycle administration process is
(1-1) Surfactant (HLB 6.39 polyoxyethylene (10) hardened castor oil ether) + ethanol (volume ratio 5:95)
(1-2) Sodium bicarbonate water (concentration 8%)
(1-3) Acetic acid (concentration 5%)
(1-4) Water, and the second cycle administration process is
(2-1) Surfactant (HLB 6.39 polyoxyethylene (10) hydrogenated castor oil ether) + ethanol (volume ratio 10:90)
(2-2) Sodium bicarbonate water (concentration 8%)
(2-3) Acetic acid (concentration 5%)
(2-4) Water.

  While aspirating with the vacuum pump 42, the surfactant + ethanol → sodium bicarbonate water → acetic acid → water was administered to the entire ground surface in this order. After each dosing process, suction was performed and the emulsion was recovered before the next liquid was administered. Dilution with water was continued until no emulsion was recovered. The position of the contaminated part was lowered as a whole, and it was confirmed that the color became lighter. However, there were still some contaminated oils in the original contaminated oil part. Subsequently, the solution of the second cycle was administered. It was confirmed that there was no contaminated oil remaining in the original contaminated portion, it moved downward, and the color became lighter. Thereafter, rinsing with continuous water flow was performed. As a result of rinsing until the emulsified liquid was not recovered, the oil in the earth tub could not be completely removed, but it was confirmed that the color was further faded and moved downward than at the end of the second cycle. . When disassembled, no oil was found in the cross section of the initial contaminated oil portion.

  At the end of the experiment, the amount of oil in the liquid in the collection server was measured to determine how much oil was collected in total or time. In that case, operation which isolate | separates oil and another liquid was performed. The measurement results are shown in FIG. The collected liquid was separated by an emulsion breaker and measured, and as a result, the total amount of oil greater than 1500 ml of oil added at the time of sample filling was determined. In an additional experiment, it was confirmed that the cause was that the surfactant (polyoxyethylene (10) hardened castor oil ether) was mixed in the oil phase. From this, when correction was made from the amount of oil obtained by the emulsion breaker, the recovered oil amount was 1025 ml and the residual oil amount was 475 ml. Therefore, it is considered that about 70% of the oil was removed in this experiment. When the cumulative amount of liquid in the collection server and the cumulative amount of collected oil are plotted, the difference in the slope of the graph is greatly different between the first cycle and the second cycle, and the purification efficiency after entering the second cycle is remarkably high. It turned out to be growing. From this, it was confirmed that a multiple cycle liquid administration process was effective.

  As a result of the accumulation of the above basic experiments, it was found that about 70% or more of the contaminated oil can be purified as a whole.

  In addition, as a result of conducting a beaker experiment using a soil sample after emulsification treatment and rinsing with only water and rinsing with activated carbon-containing water, the transparency when rinsing with activated carbon-containing water is higher, The soil sample was also smooth. From this result, it can be said that the use of activated carbon can increase the rinsing effect and reduce the amount of water used.

  When the same experiment was conducted under the following conditions A to E in which the composition and mixing ratio of the surfactant and the solvent in the administration process were changed, it was possible to purify about 70% or more of the contaminated oil, and the purification method of the present invention Was confirmed to be effective.

Condition A
(1-1) Surfactant (polyoxyethylene of HLB 5 (7.11) hardened castor oil ether) + ethanol (volume ratio 40:60)
(2-1) Surfactant (polyoxyethylene of HLB 5 (7.11) hardened castor oil ether) + ethanol (volume ratio 43:57)

Condition B
(1-1) Surfactant (polyoxyethylene (4.23) lauryl ether of HLB 10) + ethanol (volume ratio 70:30)
(2-1) Surfactant (polyoxyethylene (4.23) lauryl ether of HLB 10) + ethanol (volume ratio 72:28)

Condition C
(1-1) Surfactant (HLB 8.30 polyoxyethylene (3) lauryl ether + HLB 12.54 coconut oil fatty acid diethanolamide (mixed at a weight ratio of 36.3: 63.7 so that HLB is 11) And propylene glycol monomethyl ether (volume ratio 70:30)
(2-1) Surfactant (HLB 8.30 polyoxyethylene (3) lauryl ether + HLB 12.54 coconut oil fatty acid diethanolamide (mixed at a weight ratio of 36.3: 63.7 so that HLB is 11) And propylene glycol monomethyl ether (volume ratio 72:28)

Condition D
(1-1) Surfactant (polyethylene glycol 400 dilaurate of HLB 10.44 + sodium lauryl sulfate of HLB 20 (mixed at a weight ratio of 83.7: 16.3 so that HLB is 12) + propylene Glycol monomethyl ether (volume ratio 50:50)
(2-1) Surfactant (polyethylene glycol 400 dilaurate ester of HLB 10.44 + sodium lauryl sulfate ester of HLB 20 (mixed at a weight ratio of 83.7: 16.3 so that HLB is 12) + propylene Glycol monomethyl ether (volume ratio 53:47)

Condition E
(1-1) Surfactant (HLB 12.54 coconut oil fatty acid diethanolamide + HLB 5.19 glycerin monooleate (mixed at a weight ratio of 11:89 so that HLB is 6) + ethanol ( Volume ratio 95: 5)
(2-1) Surfactant (HLB 12.54 coconut oil fatty acid diethanolamide + HLB 5.19 glycerin monooleate (mixed at a weight ratio of 11:89 so that HLB is 6) + ethanol ( Volume ratio 95: 5)

  Moreover, when the same experiment was performed on the following conditions FG which changed the composition and mixing ratio of surfactant and a solvent in an administration process, the purification effect of contaminated oil was lower than the said conditions AE.

Condition F
(1-1) Surfactant (polyoxyethylene (1.06) lauryl ether of HLB 4) + ethanol (volume ratio 5:95)
(2-1) Surfactant (polyoxyethylene (1.06) lauryl ether of HLB 4) + ethanol (volume ratio 10:90)

Condition G
(1-1) Surfactant (HLB 6.39 polyoxyethylene (10) hydrogenated castor oil ether + sodium lauryl sulfate (mixed at a weight ratio of 51.4: 48.6 so that HLB is 13) + Ethanol (volume ratio 50:50)
(2-1) Surfactant (polyoxyethylene (10) hydrogenated castor oil ether of HLB 6.39 + sodium lauryl sulfate ester (mixed at a weight ratio of 51.4: 48.6 so that HLB is 13) + Ethanol (volume ratio 53:47)

  On the other hand, in the administration process, the same experiment was conducted when only the surfactant (the following condition H) and only the solvent (the following condition I) were used. As a result, the contaminated oil remained in the original contaminated part. The contaminated oil could not be purified.

Condition H
(1-1) Surfactant (HLB 7 polyoxyethylene (11.48) hydrogenated castor oil ether) without solvent (2-1) Surfactant (HLB 7 polyoxyethylene (11.48) hydrogenated castor oil Ether) only, no solvent

Condition I
(1-1) No ethanol and no surfactant (2-1) No ethanol and no surfactant

Explanatory drawing which shows the work procedure of the in-situ purification method which concerns on this invention. Explanatory drawing of oil pollution area and well arrangement. The xx sectional drawing. Explanatory drawing of an in-situ purification method. Process explanatory drawing which shows one Example of this invention method. Explanatory drawing which shows the example of the nozzle for liquid injection | pouring used by this invention. Explanatory drawing which shows the liquid injection | pouring condition using the nozzle. Explanatory drawing of a column experiment apparatus. Explanatory drawing of the experimental apparatus using a tabletop water tank. Explanatory drawing of a small two-dimensional soil tank experimental apparatus. The graph which shows the accumulation amount of collection | recovery oil.

Explanation of symbols

12 Contaminated Area 14 Injection Well 16 Recovery Well 20 Injection Pipe 22 Suction Pipe

Claims (13)

  A mixture of surfactant and solvent and water are injected into the contaminated area in the formation due to organic pollutants, and mixed with organic pollutants present in the formation to produce a low-viscosity emulsion by emulsification / peeling action. The in-situ location of the contaminated soil is characterized by having a process and a process of injecting a foaming agent and promoting mixing and emulsification by microfoaming action in the formation, and sucking and collecting the reduced viscosity emulsion on the ground Purification method.   The contaminated soil raw material according to claim 1, wherein the mixture of the surfactant and the solvent and the injection of water are performed stepwise so that the ratio of the mixture is high at the beginning and the ratio of water is increased later. Position purification method.   The in-situ purification method of contaminated soil according to claim 1 or 2, wherein foaming is started by separately injecting a foaming agent and a foaming aid from the ground so as to foam in the formation, and mixing and reacting in the ground.   The in-situ purification method of the contaminated soil according to any one of claims 1 to 3, further comprising a step of diluting the emulsion by continuous water flow and sucking and collecting the emulsion on the ground.   The contaminated soil raw material according to any one of claims 1 to 4, further comprising a step of injecting activated carbon-containing water, adsorbing the emulsified liquid remaining in the formation into activated carbon particles, and sucking and collecting the emulsion on the ground. Position purification method.   5. The surfactant according to claim 1, wherein the surfactant is one or a mixture of two or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. In-situ purification method for contaminated soil.   The in-situ purification method of contaminated soil according to claim 6, wherein the HLB of the surfactant in which one kind or two or more kinds are mixed is 5-12.   The in-situ purification method of contaminated soil according to claim 6 or 7, wherein the solvent is a mixture of one or more selected from solvents having a solubility in water at 20 ° C of 1% by weight or more.   The in-situ purification method of contaminated soil according to claim 8, wherein the mixing ratio of the surfactant and the solvent is 5 to 95% by weight: 95 to 5% by weight.   For the liquid injection into the formation, a horizontal spray nozzle that sprays the mist-like liquid uniformly over the entire circumference in the horizontal direction and a reverse spray nozzle that sprays the mist-like liquid uniformly over the entire circumference in the diagonally upward direction are used. The in-situ purification method of contaminated soil according to any one of claims 1 to 9, wherein liquid is pressurized and injected at an arbitrary plurality of depths into the same injection well protected by a slit screen with a hole wall.   Distribute multiple wells in the target geological survey, identify the contaminated area within the stratum by survey using them, and inject some of the wells in the contaminated area for liquid injection and at least some of the other for recovering emulsion The in-situ purification method for contaminated soil according to any one of claims 1 to 10, wherein a well outside the contaminated area is used for monitoring contamination diffusion.   12. The recovered emulsion is promoted by natural standing or physical or chemical treatment to promote oil / water separation, and the aqueous layer portion is treated by biological treatment, and the oil layer portion is treated by incineration or the like. In-situ purification method for contaminated soil. Regarding the biological treatment of the water layer containing unseparated oil, the solid-liquid separation after the treatment is the precipitation method, flotation method or membrane separation method, and when the separated sludge is returned to the aeration tank, excess oil that is not biologically treated is used. The in-situ purification method of contaminated soil according to claim 12, wherein continuous operation or batch operation is performed by extracting with sludge.

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