Method for cleaning groundwater contaminated by pollutants, in particular by organic pollutants

Abstract

The invention relates to a method for cleaning groundwater (1a, 1b) contaminated by pollutants. The contaminated groundwater is brought into contact with an adsorption material (2). Pollutants or organic pollutants are adsorbed by the adsorption material. An adsorption material is used that comprises at least one polymer, in particular a rubber, and at least one filler, in particular carbon black.

Description

[0001] Process for the purification of groundwater contaminated with pollutants, in particular organic pollutants

[0002] Description:

[0003] The invention relates to a method for purifying groundwater contaminated with pollutants, particularly organic pollutants. The organic pollutants are, in particular, hydrocarbons, preferably halogenated hydrocarbons and / or cyclic hydrocarbons, particularly aromatic hydrocarbons.

[0004] Groundwater contaminated with pollutants poses a significant environmental problem. Halogenated hydrocarbons, especially chlorinated hydrocarbons, are used in various industrial and technical sectors. For decades, the resulting waste was improperly disposed of, resulting in groundwater contaminated with these toxic substances. A particular problem is trichloroethylene (TCE), which is virtually insoluble in water and extremely difficult to remove if groundwater is contaminated.

[0005] Processes of the type described above are already known, in which contaminated groundwater is pumped from the soil to the earth's surface and there diluted with water to such an extent that it can be fed for further treatment, for example, in sewage treatment plants. This procedure requires, disadvantageously, large quantities of water and complex and energy-intensive pumping systems to transport the significant quantities of diluted groundwater to the treatment sites, which are usually located far away. Any leaks during this transport can, in turn, lead to very detrimental environmental impacts due to the release of pollutants. In this respect, the known procedure is complex, inefficient, costly, and dangerous.

[0006] In contrast, the invention is based on the technical problem of providing a method of the type mentioned above with which pollutants or organic pollutants can be removed from contaminated groundwater in a simple, effective, and cost-effective manner. Above all, further environmental pollution should be avoided.

[0007] To solve this technical problem, the invention teaches a method for purifying groundwater contaminated with pollutants, in particular organic pollutants, wherein the contaminated groundwater is brought into contact with an adsorption material, whereby pollutants or organic pollutants are adsorbed by the adsorption material, wherein an adsorption material is used which comprises at least one polymer, in particular at least one rubber, and at least one filler, in particular carbon black. According to a particularly recommended embodiment of the invention, the adsorption material is produced from at least one polymer, in particular at least one rubber, in finely divided form, and from at least one powdered filler, in particular powdered carbon black.

[0008] It is within the scope of the invention that the at least one polymer of the adsorption material is a rubber. According to a very preferred embodiment of the invention, an adsorption material comprising at least one rubber from the group consisting of emulsion styrene-butadiene rubber (ESBR), styrene-butadiene rubber (SBR), and natural rubber is used. A butadiene rubber is preferably used. The use of a food-grade rubber is particularly recommended within the scope of the inventive process.

[0009] It is further within the scope of the invention that the adsorption material comprises at least one filler in the form of carbon black. The at least one carbon black is, in particular, carbon black or industrial carbon black. Preferably, the at least one carbon black is industrial carbon black. According to a very preferred embodiment of the invention, at least one carbon black from the group “furnace black, gas black, lamp black” is used as the filler. The use of furnace black as the filler is particularly recommended within the scope of the invention. Preferably, a carbon black with an iodine absorption number of 20 to 400 mg / g, preferably 40 to 300 mg / g, particularly preferably 60 to 200 mg / g (measured according to ASTM D 1510) is used for the adsorption material. A carbon black having a BET surface area (NSA) of 10 to 800 m 2 / g, preferably from 30 to 500 m 2 / g, particularly preferably from 50 to 250 m 2 / g (measured according to ASTM D 6556).

[0010] A highly recommended embodiment of the invention is characterized in that the adsorption material consists of at least 80 wt. %, preferably at least 85 wt. %, and more preferably at least 90 wt. % of the at least one polymer – in particular of the at least one rubber – and of the at least one filler or carbon black. It is within the scope of the invention for the adsorption material to comprise further additives such as minerals and / or metal salts or the like. However, the main components of the adsorption material are the at least one polymer, in particular the at least one rubber, and the at least one filler, in particular the at least one carbon black. Very preferred within the scope of the invention is an adsorption material which consists of 10 to 70 wt. %, preferably 15 to 60 wt. %, more preferably 20 to 50 wt. %, very preferably 30 to 50 wt. %, particularly preferably 35 to 50 wt. %, most particularly preferably 40 to 50 wt.-%, more preferably 45 to 50 wt.%, for example 50 wt.% or approximately 50 wt.%, of the at least one polymer or of the at least one rubber. According to a recommended embodiment of the invention, the mass ratio of polymer (preferably rubber) to filler (preferably carbon black) is 0.5:3 to 4.5:3 and preferably 0.75:3 to 3:3. It is within the scope of the invention for the filler or carbon black to be present in excess compared to the polymer or rubber. It is also possible within the scope of the invention for the polymer or rubber to be present in excess compared to the filler or carbon black. It is furthermore possible for the mass ratio of polymer (preferably rubber) to filler (preferably carbon black) to be 1:1 or approximately 1:1.

[0011] In principle, the adsorption material can be used in various forms within the scope of the process according to the invention. Preferably, a powdered adsorption material and / or an adsorption material in the form of pellets and / or granules is used within the scope of the process according to the invention.

[0012] The process according to the invention can, in principle, remove a wide variety of organic pollutants or organic solvents from contaminated groundwater. The invention is based on the finding that the process is particularly suitable for the purification or selective purification of heavily contaminated groundwater. Heavily contaminated groundwater refers in particular to groundwater contaminated with organic pollutants undissolved in the groundwater and / or with pollutants consisting of bulky molecules. The process according to the invention has proven particularly effective in removing organic pollutants in the form of halogenated hydrocarbons, in particular in the form of chlorinated hydrocarbons, and / or in the form of cyclic hydrocarbons, in particular aromatic hydrocarbons, from contaminated groundwater.Of particular importance within the scope of the inventive process is the removal of halogenated hydrocarbons, in particular chlorinated hydrocarbons, from the contaminated groundwater. The inventive process has proven particularly effective in this regard. The removal of trichloroethylene (TCE) from the contaminated groundwater is of particular importance. TCE can be removed from the contaminated groundwater surprisingly selectively and effectively using the inventive process. Surprisingly, the adsorption material can absorb 8 to 10 times its own weight in TCE. It is within the scope of the invention that the adsorption material is used to remove undissolved organic pollutants, preferably halogenated hydrocarbons, and more preferably chlorinated hydrocarbons, from the contaminated groundwater, particularly in the contaminated groundwater.Such undissolved organic pollutants, especially halogenated hydrocarbons, have so far caused the greatest problems.

[0013] The invention is based on the discovery that the removal of organic pollutants—particularly halogenated hydrocarbons—from contaminated groundwater proceeds according to a specific mechanism. In a first step, the organic pollutants are adsorbed by the adsorption material. It is assumed that the pollutant particles are embedded in the pore structure of the adsorption material, and that swelling of the adsorption material occurs. The pollutant particles are thereby efficiently enclosed in the adsorption material and thus preferably absorbed by the adsorption material. This mechanism is particularly effective for halogenated hydrocarbons, and especially for TCE. In principle, however, other organic pollutants, particularly aromatic hydrocarbons, can also be efficiently removed from contaminated groundwater.This applies especially to organic pollutants undissolved in groundwater. The adsorption material used according to the invention is expediently a hydrophobic adsorption material. Furthermore, the at least one polymer, in particular the at least one rubber, preferably forms a polymer framework or matrix, and the polymer framework or matrix is ​​particularly preferably filled with the at least one filler, in particular with carbon black.

[0014] One embodiment of particular importance within the context of the process according to the invention is characterized in that the adsorption material loaded with pollutants is regenerated. The regeneration is preferably carried out thermally and particularly preferably by stripping. The adsorption material loaded with pollutants is heated, for example, to 90°C to 110°C. If, according to the preferred embodiment, the regeneration is carried out by stripping, a hot gas, in particular hot air, is expediently used as the stripping agent or stripping gas. The invention is based on the finding that, in particular, the adsorption material loaded with pollutants from heavily contaminated groundwater can be effectively regenerated. This applies in particular to adsorption material loaded with halogenated hydrocarbons, in particular with TCE.It is within the scope of the invention that the adsorption material, after the preferred regeneration, can be returned to its intended use or used for the further purification of contaminated groundwater. Although the pollutants, especially the halogenated hydrocarbons, are very effectively bound in the adsorption material after the contaminated groundwater has been purified, a simple regeneration can nevertheless take place, which surprisingly works particularly effectively with the halogenated hydrocarbons, especially with TCE.

[0015] Preferred alternatives of the method according to the invention are described below. - According to a first embodiment of the method according to the invention, contaminated groundwater is pumped from the soil to the earth's surface and brought into contact with the adsorption material at the earth's surface or above the earth's surface to absorb the pollutants. It is within the scope of the invention that at least one adsorption container is filled with the adsorption material and that the contaminated groundwater is passed through this adsorption container or through the adsorption material. According to a recommended embodiment, several adsorption containers filled with the adsorption material are connected in series and the contaminated groundwater flows through them. It is within the scope of the invention that the groundwater is cleaned to such an extent that the pollutants it contains are below predetermined or prescribed limit values.It is within the scope of the invention that undissolved organic pollutants and / or bulky pollutant molecules contained in particular in heavily contaminated groundwater are removed or selectively removed using at least one adsorption container. Conveniently, in a further process step, the pollutants contained in slightly contaminated groundwater can be removed from the groundwater - preferably in at least one separate cleaning container. It is within the scope of the invention that the cleaning containers are filled with the adsorption material used according to the invention. Additionally or alternatively, other cleaning substances, such as activated carbon, can also be used in the cleaning containers. Lightly contaminated groundwater means in particular groundwater that is contaminated with organic pollutants dissolved in the groundwater and / or with pollutants with less bulky molecules.It is within the scope of the invention that the groundwater is purified to such an extent that the pollutants it contains are below specified or prescribed limits. The groundwater purified by this first method according to the invention can then be returned to the soil.

[0016] According to another method according to the invention, the adsorption material is fed or pumped into the soil and brought into contact with the contaminated groundwater below the earth's surface to absorb the pollutants. Subsequently, the adsorption material loaded with the pollutants is transferred or pumped to the earth's surface. In this method, the adsorption material is expediently introduced into the soil as a suspension or in the form of an aqueous suspension.

[0017] Within the scope of the procedure described above, a second embodiment of the method according to the invention is characterized in that the contaminated groundwater is first passed through the adsorption material fed into the soil. It is within the scope of the invention that pollutants from the heavily contaminated groundwater are absorbed by the adsorption material. It is recommended that the groundwater pre-cleaned or pre-filtered in this way is transported to the earth's surface for further purification and there further purified - for example, in at least one purification tank. As already mentioned above, it is within the scope of the invention that the adsorption material used according to the invention and / or other purification substances such as activated carbon are used in the at least one purification tank.It is within the scope of the invention that pre-purified, slightly contaminated groundwater is transferred to the earth's surface, and during the latter purification—in particular in at least one purification tank—the pollutants of the slightly contaminated groundwater are removed. Preferably, the adsorption material loaded with pollutants is transferred or pumped from the soil to the earth's surface, collected in at least one collecting tank, and preferably subjected to at least one further treatment measure. Such a treatment measure may involve the preferential regeneration of the adsorption material loaded with pollutants. The groundwater thus purified of dissolved pollutants can then expediently be returned to the soil.

[0018] A third preferred alternative of the process according to the invention is characterized in that, in at least one upstream process step, the adsorption material is fed into the soil, brought into contact with the contaminated groundwater for adsorption of the pollutants, and then the adsorption material laden with the pollutants is transferred to the earth's surface and preferably collected in at least one collecting container. According to a recommended embodiment of this third alternative, at least two such process steps are carried out successively. It is within the scope of the invention that the pollutants of the heavily contaminated groundwater are removed in the process. Advantageously, after this adsorption of the pollutants according to the invention - in particular the undissolved organic pollutants - the remaining slightly contaminated groundwater is transferred to the earth's surface orand there freed from the remaining organic pollutants. This cleaning is expediently carried out in at least one cleaning tank. According to one embodiment, this is at least one of the cleaning tanks described above. The groundwater thus cleaned of pollutants can then be returned to the soil.

[0019] The invention is based on the finding that, within the framework of the inventive method, groundwater contaminated with pollutants—in particular organic pollutants—can be cleaned in a simple, efficient, and cost-effective manner. This applies in particular to organic pollutants undissolved in the groundwater, and in particular to halogenated hydrocarbons and / or cyclic hydrocarbons or aromatic hydrocarbons. The groundwater can be easily cleaned down to the pollutant limits prescribed by the authorities. Compared to the process measures described above, the disadvantageous use of considerable quantities of water and the costly, long transport of the groundwater to be cleaned are eliminated. The pollutants are reliably absorbed by the adsorption material, thus preventing further environmental impacts.The effectiveness of the process according to the invention is characterized, among other things, by the fact that the adsorption material can absorb several times its own weight in pollutants. The regeneration of the adsorption material and its reuse according to the invention are also relatively easy. The aforementioned advantages can be achieved particularly clearly when halogenated hydrocarbons or chlorinated hydrocarbons are used as pollutants. This applies in particular to the adsorption of trichloroethylene (TCE). It should also be emphasized that the adsorption material used according to the invention, in particular the hydrophobic one, is highly resistant to acids, bases, and salt solutions and can therefore also be used without problems for many of the purposes according to the invention. As a result, the process according to the invention is characterized by simplicity, efficiency, low effort, and cost-effectiveness.

[0020] The invention is explained in more detail below with reference to a drawing that represents only one exemplary embodiment. The drawing shows a schematic representation:

[0021] Fig. 1 shows a device for carrying out the inventive

[0022] Method in a first embodiment,

[0023] Fig. 2 shows the article according to Fig. 1 in a second embodiment and

[0024] Fig. 3a) to e) the object according to Fig. 1 in a third embodiment.

[0025] The figures show different embodiments of devices for carrying out the method according to the invention for purifying groundwater 1a, 1b contaminated with organic pollutants. The contaminated groundwater 1a, 1b is brought into contact with an adsorption material 2 used according to the invention, whereby organic pollutants are adsorbed by the adsorption material 2.

[0026] In the embodiment shown in Fig. 1, contaminated groundwater 1a, 1b is pumped from the soil 3 via at least one pumping line 4 to the earth's surface 5. In the embodiment of Fig. 1, two such pumping lines 4 are shown. Preferably, and in the embodiment of Fig. 1, both heavily contaminated groundwater 1a and lightly contaminated groundwater 1b are pumped to the earth's surface 5. The heavily contaminated groundwater 1a is contaminated with undissolved organic pollutants and / or with organic pollutants consisting of bulky molecules. In contrast, the lightly contaminated groundwater 1b is contaminated with dissolved organic pollutants and / or with less bulky molecules of organic pollutants. The organic pollutants can in particular be organic solvents.

[0027] Preferably, and in the embodiment of Fig. 1, the contaminated groundwater 1a, 1b at the earth's surface 5 is first brought into contact with the adsorption material 2 used according to the invention. The adsorption material 2 is expediently and in the embodiment of Fig. 1 accommodated in at least one adsorption container 6. In the embodiment of Fig. 1, for example, three adsorption containers 6 are operated in parallel. It is also possible to connect several adsorption containers 6 in series. In such an adsorption container 6, the heavily contaminated groundwater 1a is purified by the adsorption material 2 used according to the invention selectively adsorbing or absorbing the undissolved organic pollutants and / or bulky molecules of organic pollutants. Expediently and in the embodiment of Fig.1, the remaining slightly contaminated groundwater 1b, which has been pre-cleaned in this inventive manner, is fed to at least one cleaning tank 7. In such a cleaning tank 7, any organic pollutants remaining in the groundwater 1b are removed from the slightly contaminated groundwater 1b. In the exemplary embodiment in Fig. 1, for example, there are two cleaning stages for the slightly contaminated groundwater 1b, with two cleaning tanks 7 connected in series one behind the other. Furthermore, in the exemplary embodiment in Fig. 1, three cleaning tanks 7 are connected in parallel in each cleaning stage. It is fundamentally within the scope of the invention for the cleaning tanks 7 to be filled with the adsorption material 2. Additionally or alternatively, other cleaning substances, such as activated carbon, can also be used in the cleaning tanks 7. This is not shown in more detail in the figures.It is within the scope of the invention that the groundwater 1a, 1b is purified with the proviso that the pollutant content of the purified groundwater 1 is below predetermined or prescribed limit values. The purified groundwater 1 is returned to the soil 3 via at least one return line 8. In the embodiment of Fig. 1, two such return lines 8 are shown.

[0028] In the exemplary embodiment according to Fig. 2, the adsorption material 2 used according to the invention is fed into the soil 3 and brought into contact with the contaminated groundwater 1a, 1b below the earth's surface 5 to absorb the pollutants. The adsorption material 2 is expediently fed in via at least one feed line 9. The adsorption material 2 laden with pollutants is then pumped to the earth's surface 5 and there, preferably and in the exemplary embodiment, transferred to at least one collecting container 10. According to a preferred embodiment and in the exemplary embodiment, the contaminated groundwater 1a, 1b in the soil 3 is first passed through the adsorption material 2 so that the pollutants of the heavily contaminated groundwater 1a are absorbed by the adsorption material 2. The adsorption material 2 preferably functions as a pre-filter here.It is within the scope of the invention that the slightly contaminated groundwater 1b, which has been passed through the adsorption material 2 and pre-filtered, is then pumped to the earth's surface 5 for further purification. Expediently, and in the exemplary embodiment, the slightly contaminated groundwater 1b is transferred to the earth's surface 5 at the same time as the adsorption material 2 loaded with pollutants. The preferred transfer of the loaded adsorption material 2 into the at least one collecting container 10 is recommended via at least one collecting line 11. Preferably, the slightly contaminated groundwater 1b is transferred to the earth's surface 5 via at least one discharge line 12. Recommended and in the exemplary embodiment, the slightly contaminated groundwater 1b is purified at the earth's surface 5 in purification containers 7. Expediently, as in the exemplary embodiment in Fig.1 - two purification stages are provided for the slightly contaminated groundwater 1b, with two purification tanks 7 connected in series for this purpose. It has been indicated that a plurality of purification tanks 7 can be operated in parallel in each purification stage. It is within the scope of the invention that the groundwater 1 purified in the purification tanks 7 is returned to the soil 3 via at least one return line 8. - The adsorption material 2 collected in the at least one collecting tank 10 and laden with pollutants can be regenerated according to one embodiment of the invention and returned to its intended use according to the invention.

[0029] Figures 3a) to 3e) show individual process steps of a third embodiment of the process according to the invention. In a first process step shown in Fig. 3a), the unloaded adsorption material 2 is fed into the soil 3 and brought into contact with the contaminated groundwater 1a, 1b below the earth's surface 5. Expediently, the adsorption material 2 loaded with the pollutants of the heavily contaminated groundwater 1a is then transferred to the earth's surface 5 in a second process step according to Fig. 3b) and preferably collected in a collecting container 10. It is within the scope of the invention that these two process steps according to Figures 3a) and 3b) involve a pre-purification of the heavily contaminated groundwater 1a with the adsorption material 2. In this embodiment, heavily contaminated groundwater 1a still remains in the soil 3. Preferably, and in a manner shown in Fig.In the third process step shown in Fig. 3c), adsorption material 2 is then again introduced into the soil 3 and brought into contact with the contaminated groundwater 1a, 1b. In this process step, the remaining pollutants of the heavily contaminated groundwater 1a are expediently absorbed by the adsorption material 2. The adsorption material 2 thus loaded is transferred to the earth's surface 5 in a process step shown in Fig. 3d) and preferably collected in a collection container 10. Finally, only slightly contaminated groundwater 1b remains in this purified area in the soil 3. Preferably, in a fifth process step shown in Fig. 3e), the slightly contaminated groundwater 1b is pumped to the earth's surface 5 via at least one discharge line 12. Here, the slightly contaminated groundwater 1b is then expediently purified, preferably and in the exemplary embodiment in purification containers 7.This purification of the slightly contaminated groundwater 1b is carried out in principle analogous to the alternatives of the method according to the invention shown in Figures 1 and 2. It is within the scope of the invention that the groundwater 1 purified in this way is subsequently returned to the soil 3 via at least one return line 8.

[0030] All process alternatives shown in Figures 1 to 3 are excellently suited for the purification of contaminated groundwater 1a, 1b, particularly for the purification of heavily contaminated groundwater 1a. Of the adsorption material 2 used according to the invention, the

[0031] In the groundwater 1, undissolved organic pollutants and / or pollutants with bulky organic molecules are absorbed. The processes are particularly suitable for the removal of halogenated hydrocarbons, in particular for the removal of chlorinated hydrocarbons from the groundwater 1. The processes according to the invention are particularly suitable for the removal of trichloroethylene (TCE) from the contaminated groundwater 1a, 1b.

[0032] The adsorption material 2 loaded with the pollutants of the heavily contaminated groundwater 1a in the process alternatives shown in Figures 1 to 3 can be regenerated relatively easily, particularly thermally, and very preferably by stripping. Here, too, the adsorption material 2 loaded with TCE is characterized by particularly easy regeneration.

Claims

Patent claims:

1. A method for purifying groundwater (1a, 1b) contaminated with pollutants, in particular with organic pollutants, wherein the contaminated groundwater (1a, 1b) is brought into contact with an adsorption material (2), wherein pollutants or organic pollutants are adsorbed by the adsorption material (2), wherein an adsorption material (2) is used which comprises at least one polymer, in particular at least one rubber, and at least one filler, in particular carbon black.

2. The method according to claim 1, wherein the adsorption material (2) is produced from at least one polymer, in particular at least one rubber, in finely divided form and from at least one powdered filler, in particular powdered carbon black.

3. The method according to claim 1 or 2, wherein an adsorption material (2) with at least one rubber from the group "emulsion styrene-butadiene rubber (ESBR), styrene-butadiene rubber (SBR), natural rubber" is used.

4. A process according to any one of claims 1 to 3, wherein at least one carbon black from the group consisting of furnace black, gas black and flame black is used as filler.

5. The method according to any one of claims 1 to 4, wherein the adsorption material (2) consists of at least 80 wt.%, preferably at least 85 wt.% and preferably at least 90 wt.% of the at least one polymer - in particular of the at least one rubber - and of the at least one filler or carbon black.

6. A process according to any one of claims 1 to 5, wherein the adsorption material (2) to 10 to 70 wt.%, preferably to 15 to 60 wt.%, more preferably to 20 to 50 wt.%, very preferably to 30 to 50 wt.%, particularly preferably to 35 to 50 wt.%, very particularly preferably to 40 to 50 wt.%, more preferably to 45 to 50 wt.%, for example to 50 wt.% or about 50 wt.%, of the at least one polymer or of the at least one rubber.

7. Method according to one of claims 1 to 6, wherein organic pollutants in the form of halogenated hydrocarbons, in particular in the form of chlorinated hydrocarbons, are removed from the contaminated groundwater (1a, 1b) using the adsorption material (2).

8. Method according to one of claims 1 to 7, wherein undissolved organic pollutants, in particular halogenated hydrocarbons, preferably chlorinated hydrocarbons, are removed from the contaminated groundwater (1a, 1b) using the adsorption material (2).

9. Method according to one of claims 1 to 8, wherein trichloroethylene (TCE) is removed from the contaminated groundwater (1a, 1b) using the adsorption material (2).

10. Method according to one of claims 1 to 9, wherein contaminated groundwater (1a, 1b) is pumped from the soil (3) to the earth's surface (5) and is brought into contact with the adsorption material (2) at the earth's surface (5) or above the earth's surface (5) for adsorbing the pollutants.

11. A process according to any one of claims 1 to 10, wherein the adsorption material (2) is fed or pumped into the soil (3) and is brought into contact with the contaminated groundwater (1a, 1b) below the earth's surface (5) for adsorption of the pollutants, and wherein the adsorption material (2) loaded with the pollutants is transferred or pumped to the earth's surface (5).

12. The method according to any one of claims 1 to 11, wherein the adsorption material (2) loaded with the pollutants is regenerated, preferably thermally regenerated and particularly preferably regenerated by stripping.

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