DE4208591A1 - METHOD FOR CLEANING CONTAMINATED SOIL - Google Patents

Abstract

Organic pollutants may be extracted from the soil even at a temperature considerably lower than their own boiling temperature, by swirling the soil in a reactor (4) and by injecting steam (2) into the swirling soil in order to lower the boiling point of the pollutants by steam distillation.

Description

The invention relates to a method for cleaning with organic Contaminated soil contaminated with ongoing Circulation and water vapor exposure to the soil.

In the present context, the term "soil" is used other than soil and soil in the narrow sense granular solids or sludges, such as residues from others Floor washing systems, adsorbents and the like, understood, the, e.g. B. for reasons of environmental protection. Hydraulic and are available for decontamination of contaminated sites pneumatic measures, chemical / physical and biological Procedures as well as thermal treatment are available.  

Thermal cleaning processes are common to all organic as well as for volatile inorganic impurities and have the highest efficiency. In contrast to time consuming biological process is the short-term success of renovation to achieve and relatively easy to control. The Advantage over floor washing systems on chemical / physical The basis also lies in the complete recording of the pollutants that adsorb into the fine and very fine grain are. In contrast, floor washing processes have a principle Limit of application for silt portions of the soil of greater than about 20%. The highly contaminated fine grain fraction cannot be decontaminated by washing the floor, but is to be disposed of elsewhere as a residue.

A thermal process for cleaning with hydrocarbons Contaminated soil is described in DE 36 04 761 A1 specified. The cleaning is achieved by heating of the soil to the boiling point of the soil Pollutants at about atmospheric pressure. The required Heat is supplied indirectly. To remove the An inert carrier gas is used for pollutant gases. The end inert carrier gas, water vapor and hydrocarbons The mixture can then be fractionally distilled. With this method, the soil is heated to around 400 ° C heated.

DE 37 06 684 A1 describes a method for thermal separation volatile pollutants from contaminated soil described. Here, the soil together with its  Water content in a rotary kiln with the help of superheated steam gradually heated to 200 to 700 ° C that the volatile Evaporate pollutants. The water vapor and pollutant gases become a subsequent one Subject to condensation, and the main part of the water vapor is condensed out of the system and withdrawn and removes the pollutants wet-chemically or physically. Only pollutants can be separated using this method, which are volatile at the specified temperatures are.

Volatile contamination can be classified according to the state technology only at the high temperatures of pyrolysis and Combustion process - in the range from 350 to 1200 ° C - split off; these temperatures do not only effect that Decomposition of anthropogenic impurities (pollutants), but also the destruction of the natural organic Soil constituents (useful substances), that is primarily humic substances. Soils pretreated in this way are therefore only after additional processing can be used as a plant substrate.

Furthermore, the contamination transferred into the gas phase in thermal processes usually directly or in separate units burned. The downstream flue gas cleaning exceeds in terms of plant technology and costs clearly the corresponding values of the primary step, that is, the actual cleaning process. Cost-intensive measures for dust separation, for chemical Laundry, for denitrification and adsorption of  Heavy metals and ultra poison from the exhaust gas flow lead to Cleaning costs of 500, - DM / t contaminated soil and more. Finally, the thermal cleaning process because of the emission of Ultra poisons (ecotoxicological organic substances) about the exhaust gas flow is not accepted by large parts of the population.

The invention is based on this prior art based on the task of a thermal cleaning process create, which the advantages of a high efficiency, one wide field of application and short renovation periods has, without the often high boiling temperatures of the to be driven out organic pollutants would have to be stopped.

The solution according to the invention is that the organic Pollutants based on the principle of steam distillation with the help of a continuously in the sense of a Surface enlargement swirled soil continuously conducted water vapor stream expelled from the ground and be separated.

The soil is "swirled" in the method according to the invention so that the water vapor flow is as large as possible Surface offers; in this sense the "swirling" in the present connection also a very intensive revolution, mechanical fluidization of the ground or the like, e.g. B. in a fluidized bed or in a fluidized bed reactor, but also in a forced wave mixer. The more careful that  Soil is swirled, the faster the organic Pollutants except for the rest prescribed be extracted. One in the sense of the method according to the invention sufficient swirling is achieved in a reactor, whose internals work sufficiently quickly. So it's enough not a simple circulation like in a rotary kiln, rather, such a spatial distribution of the individual Particles of the soil desirable - especially with regard for efficiency and economy - that of the chemical Mechanism of steam distillation practically in the entire volume of the reactor and practically at the same time on all particles to be cleaned can take place.

The extraction of organically contaminated soils according to the invention or residues with the help of water vapor has with conventional thermal cleaning methods common that a Transfer of pollutants from the liquid or adsorbed Condition in the vapor or gas phase. However works the steam extraction used according to the invention in general already satisfactory at temperatures considerably below 200 ° C, at most in the case of very volatile contaminants, e.g. B. with tar residues, higher operating temperatures up to about 300 ° C in question. On the oxidative - and also limited in known pyrolytic working thermal process necessary high temperature level - in DE 37 06 684 A1 mentioned are still 200 to 700 ° C. preferred - can therefore be dispensed with. The invention low operating temperatures, preferably between 100 and 200 ° C lead to much less changes  the physical and chemical soil structure and to lower operating costs of the cleaning process.

In the method according to the invention, the swirled by the Soil-guided water vapor flow preferably on maintained a pressure of 0.1 to 7 bar. The amount of pressure depending on the type of contamination in the sense of a faster Reaction, in particular H₂O addition, or in the sense of Lowering of the boiling point set. In practical operation the pressure is generally close to the normal pressure of 1 bar held. Pressures of 1 to 1.5 bar are preferred. If, especially with usually very high-boiling contaminations, an additional lowering of the boiling point is desired according to a further invention, the operating pressure in the reactor, i.e. the operating pressure of the water vapor, to values down to 0.1 bar. At one would think that in the present context the lowering of the boiling point caused by steam distillation and the lowering of the boiling point due to negative pressure just add up, it has been surprising but when testing the method showed that lowering pressure below 1 bar also improve efficiency steam distillation itself. In this sense, it can be cheap in many applications be the water vapor pressure in a generally preferred range from 0.1 to 1.5 bar despite the additional effort for seals in an area more or less wide lower below 1 bar. All for a variety of reasons applied operating pressures according to another invention  advantageous if the water vapor used is unsaturated is. In particular, saturated steam should not normally superheated steam is preferred.

The use of steam is one at all, if not that essential feature of the invention. The steam is used according to the invention not primarily for heating the in if possible small particles swirled cleaning substance, but to seemingly lower the boiling point of this substance. According to the invention, it does not become more or less more liquid, possibly like in a rotary kiln slowly circulating swamp heated with the help of steam, such that contamination present in the liquid sump evaporate due to the higher bottom temperature, but they become those in the whirled up particles of the earth contained contamination molecules or the like by wrapping driven out of the particles with H₂O molecules and transported away with the steam.

Basis of the method for floor cleaning according to the invention with steam is the application of those used in large chemicals Steam distillation. This is the most important special case of so-called carrier steam distillation, with the high-boiling, hydrophobic substances often have it separated at 100 ° C. Because of their real Such substances usually have a very high boiling point by itself a correspondingly low one Vapor pressure, which is common with the water vapor pressure added to the total pressure (see Dalton's Law of  Partial pressures). With steam distillation, however, occurs a solvation and consequently a considerable lowering of the boiling point of organic pollutants. the molecules the substance to be distilled is namely through Water molecules enveloped, making their real chemical Character is masked. These "quasi-water atoms" can distill off at relatively low temperatures.

In chemical engineering, steam distillation either takes place in mixtures with water or by blowing in steam into the bubble sump (still). Steam distillation is in the laboratory, e.g. B. in nitrogen determination according to Kjeldahl, or used in the representation of quinone. In technology, it is used in the refining of fatty acids as well as in the production of essential oils and Essences.

When using the steam treatment according to the invention for soil remediation, it was found that not only - how expected - volatile, but surprisingly also volatile organic pollutants according to the relevant State of the art of separation by distillation from soil - at the temperatures used - not at all should be accessible, must be separated without residue and that the treated soil is practically unchanged in its physical properties, e.g. B. regarding the grain size distribution, remains. as a further advantage comes - as I said - still surprisingly, the useful substances essentially remain. This unforeseen effect does that  Steam cleaning of the type according to the invention is particularly valuable, because they are the humic substances integrated in the soil matrix spares.

An essential further advantage of the cleaning method according to the invention results when separating the organic Pollutants from water vapor following extraction from the ground. A complex, multi-stage gas scrubbing is not necessary in the water vapor process according to the invention, if the in the aforementioned first step separated and removed with the water vapor organic Pollutants according to another invention in a second Process step in the presence of water vapor Use of temperatures up to about 500 ° C and pressures of cracked up to 7 bar, i.e. chemically split and / or being transformed. The water vapor as a carrier component thus free again and can be used again in the cycle for steam distillation be used. Alternatively, the vapors laden with pollutants already separated from the ground by the way, even in the first process step alone - without the second process step, the condensation.

According to yet another invention, they can be removed from the ground separated pollutants with the addition of oxygen or Air largely into simpler, essentially harmless Substances are converted or split. The pollutants can also directly to H₂O, CO₂, NH₃ or sulfur-containing or halogenated organic substances in the corresponding  Mineral acids are implemented.

In the method according to another invention, the with the Water vapor at the low temperatures from the contaminated Soil-driven organic pollutants preferably in a single apparatus or in a single Containers with a colder zone up to about 200 ° C and one hotter zone up to about 500 ° C for each for cracking provided temperature and pressure values brought. Accordingly the organic pollutants are caused by steam splitting - optionally also under oxidative Reaction conditions - too simple, not or less toxic Molecules such as alcohols, ammonia, carbon dioxide and / or Water decomposes. For example, alcohols are formed by hydrolysis of halogenated hydrocarbons. Organic Nitriles can match with water at higher temperatures Carboxylic acid amines or carboxylic acids are saponified.

As said, the extraction method according to the invention can of organic pollutants in the same reaction container like the downstream process for splitting or converting of organic pollutants occur when the particular Reaction vessel a correspondingly colder zone and one suitably hotter zone. Basically, e.g. B. if different pressures are desired, it is also possible the two process steps in two series Run reaction units. In the first unit the contaminated soil is then brought in and under  constant circulation by steam distillation from the organic Free pollutants. In the second unit the splitting and / or conversion of the water vapor carried organic pollutants.

During the first process step for possible humic substances and the like substantially harmless temperatures can be carried out in the second step much higher temperatures are used because it is here only about the conversion or decomposition of the organic Pollutants go and useful substances are no longer adversely affected can be. To save energy and if necessary however, it can be beneficial to improve efficiency be in the subsequent to the inventive method A catalyst or a conversion step Use reaction mass.

When using the extraction process, the grain size of the materials to be cleaned in a range from 0.001 to 20 mm include. With these granular values, there are sufficient short diffusion paths for water vapor on the one hand and guarantee the organic pollutants to be separated on the other hand.

Finally, the extraction process can basically both discontinuously in a boiler and continuously, e.g. B. in a fluidized bed reactor, fluidized bed reactor or forced wave mixer. For continuous The process may also be continuous  Aftertreatment of the water vapor for the purpose of conversion or splitting of organic pollutants and recovery of Water vapor, at least for partial recovery be.  

Based on exemplary embodiments and drawings, others Details of the invention explained. It shows

Fig. 1 is a system for the steam extraction organic contaminated soils and the like;

Figure 2 is an ion current chromatogram showing contamination of a soil sample prior to treatment.

Fig. 3 is an ion current chromatogram of the bottom of Fig. 2 after treatment (T = 100 ° C, p = 1 bar);

Fig. 4 is an ion current chromatogram of the condensate of Fig. 3 during the first thirty minutes;

FIG. 5 is an ionic flow chromatogram of the condensate of FIG. 3 during the half hour following the first 30 minutes after the start of the extraction;

Fig. 6 is an ion current chromatogram of the condensate of Fig. 3 from sixty to one hundred and twenty minutes after the start of the extraction;

Fig. 7 is a Ionenstromchromatogramm illustrating the contamination of a prepared in the laboratory in front of the water sample to be executed for a detoxification steam distillation;

Fig. 8 is a Ionenstromchromatogramm by steam distillation over silica glass at T = 500 ° C of a condensate obtained from the water sample shown in FIG. 7;

Fig. 9 is a Ionenstromchromatogramm by steam distillation over copper at T = 500 ° C the resultant condensate from the water sample shown in FIG. 7;

FIG. 10 is an ion current chromatogram depicting the residual contamination of the distillation sump of the water sample of FIG. 7; and

Fig. 11 cleaning performance of a reactor depending on the degree of turbulence in the soil.

The water vapor extraction according to the invention of an organically contaminated soil is described below in a first example ( FIGS. 2 to 6). In a second example ( FIGS. 7 to 10) results of the detoxification of organic contaminations of a water vapor stream are given.

Fig. 1 shows a test facility for water vapor extraction of organically contaminated soils or residues. With the help of a steam generator 1 , steam 2 is passed via a valve 3 into a (heated) reaction mixer 4 . In the reaction mixer 4 5 contaminated solid 6 , z. B. contaminated soil, entered in the direction of the arrow. On the discharge side 7 , the cleaned solid 8 is discharged in the direction of the arrow. Within the mixer 4 , the introduced solid 6 is constantly using internals 9 , z. B. blades or the like, swirled so that new surfaces of the granular solid form continuously. At the same time, the water vapor 2 is continuously passed directly through the swirled solid. The reaction mixer 4 of FIG. 1 has a heating mantle with inlet 11 and outlet 12 for a heating medium, for example. B. steam.

The reaction mixer 4 used for soil treatment in FIG. 1 can, for example, operate in batch mode and can be charged with a conventional steam generator 1 with preferably superheated steam. After flowing through the solid in the reaction mixer 4-laden contamination vapors can via a line 1 3 - possibly with valve 14 - passed into a condenser 15, deposited there, and (not shown) in a parallel are subjected plattenabschneider phase separation. The condensate 16 can leave the condenser 15 via an outlet 17 . The valve 14 , like the valve 3 , serves to set or maintain a specific vapor state in the reaction mixer 4 .

Example 1 Water vapor extraction from an organically contaminated soil (first stage of the procedure)

The investigations were based on a system according to FIG. 1. Contaminated soil from a waste disposal site was used as the feed material (solid). Before the treatment, the floor had a dark brown to black appearance and consisted mainly of middle sand with gritty and slightly silty secondary components. Table 1 shows the chemical parameters of the sample used on the site.

Table 1: Chemical parameters of the sample used

In addition, the soil was treated with a phenol mix (tracer) artificially contaminated. It is a mixture of the same Mass fractions from 2-chlorophenol, 2,4-dichlorophenol, m- Cresol, 2,4,6-trichlorophenol with boiling points between 180 and 230 ° C. The soil was acidified to pH 3 with H₃PO₄.

The Figs. 2 to 6 show Ionenstromchromatogramme of the extracts of the soil before and after treatment, as well as the different duration of the experiment condensate samples continuously drawn. The abscissa represents the retention time (time steps) of the sample constituents. The intensity value noted on the right ordinate is used to compare different chromatograms. Identical or similar numerical values allow a direct comparison of the peak heights and thus also a first approximation of the concentration. The detected relative ion current (RIC) is plotted on the left ordinate. The value 100% is automatically assigned to the highest peak detected.

In addition to specifying the total chemical parameters of the contaminated soil in Table 1, the chromatogram of FIG. 2 (soil before treatment) allows the contamination spectrum to be characterized. .: In Figures 2 to 6

1 o-cresol
2 2-chlorophenol
3 2,4-dichlorophenol
4 2,4,6-trichlorophenol
5 C₁₂H₂₆
6 C₁₃H₂₈
7 C₁₄H₃₀
8 C₁₅H₃₂
9 C₁₆H₃₄
10 C₁₇H₃₆
11 tributyl phosphate
12 hexachlorobenzene (HCB)
DCB dichlorobenzene isomers

Before the steam treatment, various alkanes are C₁₂ to  C₁₇, hexachlorobenzene (original contamination) and tributyl phosphate (Plasticizer) detected. The proportions of the untreated Soil added phenol mix (0.4 h / kg) approximately recovered using GD / EDC analysis (GD / EDC = Gas Chromatography / Electron Detecture Capture).

The relevant process parameters are summarized below listed:

Weight: 90 kg soil sample
Contamination: approx.8.5 g / kg KW = hydrocarbon). Additional doping with 0.4 g / kg phenol mix.
Reactor pressure / temperature: p = 1 bar, T = 100 ° C.
Steam throughput: m _D = 65 kg / h
Test duration: 120 minutes
Soil sampling: before / after experiment
Sampling condensate: mixed samples 0-30 ′, 60-120 ′.

The analysis of the soil sample after the steam treatment at T = 100 ° C. and p = 1 bar shows a completely different picture than the starting material according to FIG. 3 (soil after treatment).

The alkanes found before treatment are as well as that "Mountain" of alkane degradation products, except for the slightest residue C₁₄ and C₁₅ disappeared. This also applies to hexachlorobenzene to. The tracer substances (phenol mix) are up to below enriched the detection limit. Only the plasticizer opposes water vapor extraction.  

The analyzes of the condensates obtained reflect the depletion of the soil in terms of contamination. A majority of the alkanes, their biodegradation products ("Berg"), contain the non-volatile hexachlorobenzene, in a condensate sample from the first thirty minutes (0-30 min; Fig. 4, T = 100 ° C, p = 1 bar) (Boiling point 322 ° C!) As well as the tracer substances. Furthermore, 9-ethyl carbazole can be identified as a nitrogen-containing compound. Also proven dichlorobenzene is due to residues from other test series.

This contamination spectrum continues to weaken in the extracts of the further condensate samples (T = 100 ° C; p = 1 bar) ( Fig. 5 and 6; condensate from the period 30'- 60 'or 60'-120' after the start extraction).

Tributyl phosphate was not driven out of the soil ( Fig. 2 and 3), nor is it found in the condensate or water samples ( Fig. 4 to 6).

In the condensate the first half hour (0-30 ′) are estimated Contain 90% of the contamination. Between thirty and sixty minutes (30'-60 ') after starting steam treatment will be 5-8%, in the following sixty to one hundred and twenty Minutes (60'-120 ') are only 2 to 5% of Contamination found.

Example 1 shows that with the use of steam  100 ° C the entire existing contamination spectrum from the Soil could be removed. Even existing non-volatile ones Substances were driven out to below the detection limit. For example, all hydrocarbons and Hexachlorobenzene as an example of less volatile impurities after two hours of treatment over 98% removed. Already at a steam temperature of 100 ° C the as Tracer used chlorinated phenols completely expelled.

Example 2 Detoxification of organic contaminants in the water vapor stream (Second stage of the procedure)

In laboratory tests, water was mixed with contaminants, here organohalogen compounds ( FIG. 7, contamination of the water sample before steam distillation). A laboratory apparatus was loaded with this mixture. The following substances are identified in FIGS. 7 to 10:

1 hexachlorobutadiene
2 tetrachlorobenzene
3 hexachlorocycloheptadiene
4 tetrachlorobenzene
5 bromotrichlorobenzene
6 pentachlorobenzene
7 hexachlorobenzene
8 octachloronaphthalene

X₁-X₁₀ other halogenated substances present
X _N newly formed halogenated substance,
P phthalate

In the apparatus loaded with the prepared mixture became steam at a temperature of 100 ° C under normal pressure initiated. The emerging, with contamination loaded steam then entered a quartz U-tube (Length 80 cm, diameter 1.8 cm) and was at 500 ° C heated (tube furnace). The superheated steam was then condensed in a cooler, the condensate was on Brought to room temperature.

Two different variants were tested in the tests:

• a) Steam distillation over quartz at 500 ° C
• b) Ditto, but over copper granulate (⌀ around 1 mm)

Fig. 8 shows the - Fabric spectrum found in the condensed vapor (the condensate by steam distillation überr silica glass at T = 500 ° C) - to flow through the quartz glass tube.

The condensates were worked up by stirring with a mixture of hexane and acetone (9: 1). After drying over Na₂SO₄ the extracts were concentrated to a volume of 1 ml. The analysis was carried out using GC / MS (Gas Chromatography / Mass Spectrometry). The volume of treated in the same way Reference solution (contamination without water vapor treatment) was  0.5 ml, which means the solution was twice as concentrated like that of the extracts.

The presence of alkylated aromatics as well as the occurrence of polyaromatic compounds, such as. B. naphthalene, in Condensation of the distillation attempt over quartz glass means that carbon-halogen bonds broken in the molecules were. The mean residence time of the steam in the hot Quartz U-tube was around 1 second.

Even if the contamination in the test described is quantitative, as due to the short exposure time to the high Expected temperature, hardly decreasing, let these results conclude that if the Steam in the hot zone of the apparatus an increasing number of carbon-halogen bonds and thus break the connections are broken down into less toxic substances can.

When using a catalytically active element, such as copper (variant b), the decrease in quantity relative to the originally present contamination amounts is evident ( Fig. 9: condensate after steam distillation over copper at T = 500 ° C). Thus compounds such as hexachlorobutadiene, the highly chlorinated compound octachloronaphthalene and the halogenated compound X₉ ( FIG. 7) are completely absent. A comparison with the ingredients (residual contamination) of the distillation sump ( Fig. 10) excludes that this could be the result of an apparent degradation caused by incomplete steam distillation. Substances with comparable retention times and mass spectra are given the same names in all chromatograms.

Also the alkyl compounds found in the distillation over quartz glass can no longer be proven. That means for further destruction or dechlorination of the corresponding Molecules both through the catalytic action of copper as well as due to the longer dwell time the lower permeability of the related copper granules there. The mean stay was around 2 to 3 Seconds. Here too, the result is correspondingly longer Exposure time an even higher efficiency.

Overall, the tests with contaminations typical of contaminated sites showed that the process is simple, not optimized version for the desired detoxification of the water vapor flow of expelled pollutants is advantageous. The experiments prove that the detoxication of organic halogen Compounds under certain reaction conditions by the occurrence of carbon-halogen bond breaks can be carried out successfully.

Fig. 11 shows the results of comparative tests on a fluidized-bed reactor, which was operated at two different speeds. In both cases, the input material was a soil contaminated with mineral oil with about 1% hydrocarbon content. Two speeds of the fluidized bed reactor were investigated:

At n = 30 / min, the floor became just like in a concrete mixer or circulated in a rotary kiln. At n = 80 RPM the floor was swirled so violently inside the reactor that permanently a very large grain surface for the water vapor was accessible.

The results of the comparison tests are shown in the corresponding two curves in FIG. 11.

At n = 60 rpm, cleaning can be accomplished in two hours not completely.

At n = 80 rpm the vapor / pollutant contact was so good that Practically complete cleaning after just 80 minutes was achieved.

Fig. 11 shows in the abscissa, the duration of treatment in minutes, and in the ordinate the amount of the pollutant removal percentage. 100% means complete cleaning.

Claims (16)

1. A method for cleaning soil contaminated with organic pollutants in the event of continuous circulation and steam application to the soil, characterized in that the organic pollutants are expelled from the soil and separated from the soil by means of a water vapor distillation with the aid of a water vapor stream continuously conducted through the continuously swirling soil will. 2. Procedure according to claim 1, characterized, that unsaturated water vapor is used and, in particular according to the type and concentration of the pollutants to be separated, is regulated. 3. The method according to claim 1 or 2, characterized, that the balance between that adhering to the ground solid or liquid organic phase of the pollutant and the organic phase already in vapor form is shifted towards the vapor phase. 4. The method according to at least one of claims 1 to 3, characterized, that a steam flow of about 100 to 200 ° C through the swirling soil is conducted.   5. The method according to at least one of claims 1 to 4, characterized, that the water vapor flow with about 0.1 to 7 bar, in particular with about 0.1 to 1.5 bar, preferably close to normal pressure, is passed through the swirling soil. 6. The method according to at least one of claims 1 to 5, characterized, that separated in a first step and organic pollutants removed with water vapor a second process step in the presence of water vapor and at temperatures up to about 500 ° C and pressures up to cracked to about 7 bar, that is chemically split and / or being transformed. 7. The method according to claim 6, characterized, that the second process step with the addition of oxygen or air is running. 8. The method according to claim 6 or 7, characterized, that the organic pollutants in the second process step largely in simpler, essentially harmless substances or directly to H₂O, CO₂, NH₃ or, in the case of sulfur-containing or halogenated organic substances, in the corresponding mineral acids cracked, that is chemically split or being transformed.   9. The method according to at least one of claims 6 to 8, characterized, that the separation of the organic pollutants in the first process step and the splitting or conversion of these substances in the second process step in a single apparatus or is carried out in a single reaction container, which is a colder zone up to about 200 ° C or a hotter one Zone with a temperature up to about 500 ° C. 10. The method according to at least one of claims 6 to 8, characterized, that the two process steps connected in two in a row Reaction units are carried out, in which first unit the contaminated soil is entered as well there the organic pollutants are expelled and wherein in the second unit, the splitting or conversion the organic pollutants carried with the water vapor is carried out. 11. The method according to at least one of claims 6 to 10, characterized, that the splitting or conversion of the organic pollutants in the second process step using a catalyst or a reaction mass is executed. 12. The method according to at least one of claims 1 to 11, characterized, that the soil during the first process step with With the help of internals, such as screws, shovels or roller mills,  is so swirled that constantly new surfaces are formed, and that the water vapor directly through the swirling soil is passed through. 13. The method according to at least one of claims 1 to 12, characterized, that the grain size of the soil to be cleaned is in one area from 0.001 to 20 mm is set to be sufficient short diffusion paths for water vapor on the one hand and the ensure organic pollutants to be separated on the other hand. 14. The method according to at least one of claims 6 to 13, characterized, that discontinuous in the first and / or second process step is worked. 15. The method according to at least one of claims 6 to 14, characterized, that in the first and / or second process step with continuous Run through the swirled soil or with continuous post-treatment of the water vapor worked becomes. 16. The method according to at least one of claims 1 to 15, characterized, that each part of the water vapor is circulated and another part of the water vapor is condensed.