remediation of oil-contaminated soil using the cleansoil technology

ISSN 1064�2293, Eurasian Soil Science, 2011, Vol. 44, No. 4, pp. 453–461. © Pleiades Publishing, Ltd., 2011.Original Russian Text © A.V. Zakharchenko, Yu.V. Korzhov, E.D. Lapshina, M.G. Kul’kov, D.M. Yarkov, D.I. Khoroshev, 2011, published in Pochvovedenie, 2011, No. 4, pp. 495–504.

453

INTRODUCTION

A large amount of oil is dangerous for living organ�isms, while small oil quantities may be used as nutri�ents for many groups of microorganisms [2, 8], espe�cially when the oil is dissolved in water. When the mainpart of the oil and oil products are collected in thesoil’s surface and the topsoil, two ways for the remedi�ation of oil�polluted soils are used: (1) plowing withthe application of mineral fertilizers and oil�consum�ing microorganisms and (2) the removal of the pol�luted surface soil layer and its further regenerationunder semi�industrial conditions [12]. Both ex situmethods produce a disturbance of the fertile topsoiland the complete destruction of the natural soil. Theuse of conventional methods may be difficult becauseoil�polluted areas may be occupied by buildings, con�structions, roads, etc.

According to the innovative technology, perforatedplastic drainage pipes are put into the soil by horizon�tal boring and the soil above them remains undis�turbed. This type of soil drainage is efficient at theamelioration of excessively moistened soils [5]. Forthe soil purification, the drainage pipes are filled withan adsorbent in long bags whose diameter is equal tothat of the pipes. A concentration gradient is formedbetween the sorbent and the pollutant in the soil. Itgenerates a diffusive flow of the pollutants from the soiltowards the adsorbent. The greater the differencesbetween the sorption properties of the sorbent and thesoil, the more effective the uptake of the pollutant bythe adsorbent and the soil purification. The soil drain�age system made of perforated pipes requires excessivemoisture and favors the optimization of the soil water

regime. The pollutant is removed from the soil bychanging the adsorbent. The CLEANSOIL technol�ogy is protected by a European patent (no. EP 1 009553 B1) and is now realized in EEC countries, theRussian Federation, and Ukraine.

The CLEANSOIL technology is aimed at soil puri�fication from pesticides and heavy metals. The scientistsof the Institute of Problems of Nature Use and Ecologyof the National Academy of Sciences of Ukraine haverevealed that the content of water�soluble pesticidesdrops to 0.001–0.335 mg/kg when a chernozem iswashed with water. At natural moistening, the drop isonly 30%. The simazine content in the adsorbent risesconsiderably and is 1.112–1.288 mg/kg [13, 15].

Using the data given on the Internet, scientists ofthe Institute of Problems of Economic Ecology of theNorth and the Kola Research Center of the RussianAcademy of Sciences have studied the possibility ofthe use of the CLEANSOIL technology for the purifi�cation of soils contaminated by heavy metals near theSeveronikel’ Enterprise. The investigations haveshown that the method may be used for the purifica�tion of soils contaminated by heavy metals under theexisting infrastructure. If there are diverse pollutants,this method is practically the only one to be used.

The CLEANSOIL technology is interestingbecause it permits one to purify fertile topsoil withoutits disturbance, especially when the frozen ground isdrilled in the winter. Our participation was confirmedby the leaders of the project (The Sixth FrameworkProgram: An Innovative Method for the on SiteRemediation of polluted Soil under the Existing Infra�structure [http://inep.ksc.ru/index.php]). It was

DEGRADATION, REHABILITATION, AND CONSERVATION OF SOILS

Remediation of Oil�Contaminated Soil Using the CLEANSOIL Technology

A. V. Zakharchenko, Yu. V. Korzhov, E. D. Lapshina, M. G. Kul’kov, D. M. Yarkov, and D. I. Khoroshev

Yugorsk State University, ul. Chekhova 16, Khanty�Mansiisk, Tyumen oblast, 628012 RussiaE�mail: [email protected]

Received December 17, 2009

Abstract—Approbation data of the innovative CLEANSOIL technology of soil purification after oil pollu�tion are given. Drainage pipes filled with an adsorbent with microorganisms placed in the soil are used. It isrevealed that the content of hydrocarbons under the technological constructions (metal columns and reser�voirs) rises in comparison with the open oil�polluted areas. It is shown that the oil is destroyed quicker underthe constructions versus in the open areas. The microorganisms better assimilate the n�alkanes with C14chains than the C32–40 hydrocarbons. The application of a combined technology based on the sorption andreduction of the hydrocarbons by microorganisms makes it possible to quickly reduce the soil pollution by oilproducts without the soil cover’s disturbance.

DOI: 10.1134/S1064229311020189

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decided to make the scheme of the experiment morecomplicated and to impregnate a part of the adsorbentwith hydrocarbon�reducing microorganisms (HCRM)prior to its placement into the perforated pipes. Wesuppose that HCRMs begin to move to the earth’s sur�face from the adsorbent in the perforated pipes at themoment of the pipe’s lining. It decomposes the hydro�carbons (HC) and reduces their content in the soil.

The experiment shows that the oil�consumingmicroorganisms are rather effective and may be usedfor the rehabilitation of oil�contaminated soils [14].The perforated pipes with the adsorbent are not onlythe source of the HCRM and are also an obstacle forthe HC decomposition products migration to thegroundwater. This is another advantage of this method.

A native HCRM culture was extracted from soil sam�ples from the test plot by a group of biotechnologists ofWarsaw Technological University. Its HC�decomposingactivity was enhanced. The Polish scientists obtainedenough active culture for filling a portion of the adsor�bent in the perforated pipes by the beginning of theexperiment. For this aim, they used equipment (a fer�menter) brought from Poland at the test plot.

The experiment performed according to theCLEANSOIL program is aimed at assessing the possi�bility of using the soil drainage system filled with

adsorbent with HCRM in order to decrease the con�tent of HC related to oil pollution in the undisturbedtopsoil in the open area and under industrial construc�tions.

OBJECTS

We chose a plot in the area of the functioningpetroleum storage depot of Yugorsk State Universitywithin the city of Khanty�Mansiisk in order to studythe possibilities of using the CLEANSOIL technologyfor the purification of soils contaminated by oil prod�ucts. The area is located in the Irtysh River floodplain.

The quadrangle�shaped test plot is 11 m wide and33 m long. Its total area is 363 m2 (Figure). The largestpart of the plot is an open area. There are two techno�logical constructions. The first construction with anarea of 48 m2 is a metal box for oil products storage inmetal barrels. The box is set on metal supports at aheight of 1 m from the earth’s surface. The secondconstruction is a metal reservoir for the storage ofwaste oil products 50 m2 in area set on the soil’s sur�face.

The test plot was completely covered by crude oil in2002 with the exception of the areas under the con�structions. The microrelief was a cause of the uneven

1

Construction 2

0 сm

Construction 2 Construction 1

Construction 1

2 3 4 5

33 m

11 m

20 сm

40 сm

60 сm

(a)

(b)

The horizontal (a) and vertical (b) schemes of the pipes at a depth of 60 cm in the open area and the under the constructions.Designations: (1) the soil’s surface; (2) the soil contaminated with oil; (3) the adsorbent with the HCRM; (4) the pure adsorbent;(5) the place of the oil spill.


REMEDIATION OF OIL�CONTAMINATED SOIL USING 455

oil distribution on the soil’s surface. The oil was cov�ered by a sand layer whose surface was leveled, so theboundaries of the oil spill cannot be determined, butthe spill’s area exceeds the plot’s area. That is why weshow only the place of the beginning of the oil spill inthe figure. This uncertain situation caused additionaldifficulties at the soil sampling.

The location of the perforated horizontal pipes wascoordinated with the leaders of the CLEANSOIL project.The mean distance between the pipes is 1000 mm, theirdepth in the oil is 600–500 mm, and their diameter is150 mm. All the pipes were placed parallel to the longside of the test plot by the method of horizontal drilling,and their number was 33. The volume of the groundfrom the soil’s surface to the surface of the pipes (to bepurified) is about 33 × 11 × 0.5 = 181.5 m3.

There were no other oil spills in the area of thepetroleum storage depot, and a mosaic plant cover wasformed there within five years after the oil spill. Thecontaminated sand layer is underlain by a stratifieddeposit: a buried soddy alluvial soil on stratified allu�vial sands.

THE MORPHOLOGICAL AND PHYSICOCHEMICAL SOIL PROPERTIES

The soil profile includes three layers: (1) the depos�ited sandy loamy man�made one (C0rr and Crr 10 cmthick), (2) the buried profile of the soddy alluvial soil(Ah and AhC, 34 cm thick), and (3) an alluvial strati�fied deposit (C1 and C2, 52 cm thick). The descriptionof the stratified alluvial primitive soil is as follows.

COrr, 0–3 cm, dark brown, moist sand with brownmottles with impregnation by organic matter ofunknown origin. It contains mazut and few plant resi�dues.

Crr, 4–10 cm, brownish gray, stratified, structure�less, and moist sand with few plant roots.

Ah, 11–26 cm, gray, buried, sandy loamy, powdery,and a moist humus horizon with few plant roots.

AhC, 26–45 cm, light brown, medium�grained,structureless, moist sand.

C1, 46–65 cm, stratified, sandy and sandy loamy,alluvium with clay lamellae.

C2, >70 cm, grayish–bluish and structureless sand.Water�saturated.

According to the soil classification [6], the soils aredefined as lithostrates on a toxilithostrate of buriedand chemically transformed alluvial weakly soddy soil.

The top technogenic stratified layer (0–20 cm) isspecified by a high content of medium and coarse sand(>0.25 mm). It is silty coarse sandy loam (Table 1). Ata depth from 20 to 40 cm, there is cohesive fine sand.It is dominated by the fine sand (91%) fraction. At adepth of 40–60 cm, the content of coarse silt increasesand that of fine sand decreases. With respect to thecontent of physical clay (5–10%), the layer is definedas cohesive coarse�silty sand. In the 60� to 80�cm�thick layer, the content of fine sand increases (finecohesive sand). In the 80� to 10�cm�thick layer, thecontent of coarse silt (0.05–0.01 mm) rises, contraryto that of fine sand, and it is called coarse�silt sandyloam. At a depth more than 100 cm, there is cohesive(almost loose) fine sand.

Three layers (0–20, 40–60, and 80–100 cm�thick)are specified with respect to the relative increase in thecontent of physical clay (<0.01 mm). Thus, withrespect to the content of coarse sand, fine silt, andphysical clay, the soil profile is divided into three layerswith elevated and three layers with low contents ofphysical clay. Among the layers with an elevated con�tent of physical clay, a layer with a high content of finesand and two layers with the predominance of thecoarse�silt fraction are specified. This testifies to thefact that the first layer is alien. Therefore, we may con�firm that the layer 10–15 cm thick was deposited afterthe oil spill.

The soils of the test plot are saturated with mineralnutrients of plants and microorganisms, which is nottypical for such low productive soils (Table 2). Nitro�gen fertilizers were probably used with the sand addedto the contaminated soil. The content of availablenitrogen in the soils is very high (102 mg/100 g) for thelayer with the sandy loamy texture. The nitrogen con�tent drops with the depth to low values. The content ofavailable phosphates (according to Kirsanov) in thetop layer is lower than the normal one (6.4 mg/100 g).

Table 1. Particle�size distribution; fraction contents, %

Hori�zon

Depth, cm

Fraction size, mm Physical clay Physical sand

>0.25 0.25–0.05 0.05–0.01 0.01–0.005 0.005–0.001 <0.001 <0.01 >0.01

C0rr 0–3 12.7 75.0 2.9 2.6 0.7 6.1 9.4 90.6

Ah 15–20 0.6 90.9 2.7 0 0 5.8 5.8 94.2

AhC 35–40 0.8 79.0 11.4 0.2 0.7 5.5 8.8 91.2

C1 55–60 3.2 87.7 3.2 0.4 0 5.5 5.9 94.1

C2 75–80 1.1 78.3 10.7 1.3 1.3 7.3 9.9 90.1

C2 95–100 0.5 91.6 2.4 0 0.1 5.4 5.5 94.5

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At a Р2О5 content lower than 8 mg/100 g, the soils areassigned to those poorly provided with phosphorus.

There is a drop in the phosphorus content to4.3 mg/100 g at a depth of 60–80 cm, and then it risesup to 11 mg/100 g in the deep part of the soil profile(stratified sand of river channel facies at a depth ofmore than 70 cm). There was soil groundwater here inthe period of the soil sampling.

The iron content is low, which may be evidenced bythe absence of morphological features of iron hydrox�ides' precipitation and is confirmed by the analyticaldata. The soils of the test plot are characterized by alow content (0.10–0.32%) of oxalate�soluble ironcompounds (the Tamm extract). The iron content ishigh in the 80� to 100�cm�thick layer, which is locatedabove the groundwater table and has an alternatingredox regime. This creates conditions for the accumu�lation of iron hydroxide films. The soils of the test plotare also characterized by a low content of manganese(0.003%) and aluminum (0.0003–0.008%) in theTamm extract, which testifies to the fact that they aremobile and removed beyond the soil profile.

The pHwater is close to neutral and varies slightly(6.3–6.9) in the soil profile (Table 3). The pHsalt islower by 1 as compared to that of the water extract,which points to the considerable effect of exchange�able hydrogen.

The total acidity is not high for soils of light textureand with a low aluminum content. The content ofexchangeable hydrogen is the lowest in the AhC hori�zon and the highest in the C2 horizon with clay lamel�lae. The layers with an increased physical clay contentdisplay an increase of their total acidity.

The content of exchangeable Ca2+ in the sandysoils of this natural zone is 4–5 mg�equiv/100 g. Thecontent of exchangeable Mg2+ is rather high in the0� to 80�cm�thick layer and reaches 2.8 mg�equiv/100 g in the 20� to 40�cm�thick layer. In thelayer deeper than 80 cm, the content of exchangeableMg2+ drops to 1.2 mg�equiv/100 g.

The cation exchange capacity is only 7–9 mg�equiv/100 g. It is higher in the layers with an increasedcontent of physical clay. The base saturation in the tophorizon is 86%. In some layers, it rises up to 92.5%because of the predomination of the coarse� and fine�sand fractions with a small cation exchange capacity.

The soil ground water appears at a depth of 70 cmand causes a bluish tint of the sand deposits of theC2 horizon. For comparison, we sampled the soilground water from the borehole in the central part ofthe test plot and in similar geomorphologic conditionsat a great distance from the test plot. The electricalconductivity of the water at the test plot is two timeshigher than of the water sampled at the floodplain at adistance from the industrial enterprises.

Table 2. Content of humus and available nitrogen compounds according to Shkonde, the phosphorus according to Kir�sanov, the Fe2O3 according to Tamm, the MnO according to Tamm, and the Al2O3 according to Tamm (for absolutely dryweighed portions)

Horizon Depth, cmN according to Shkonde P2O5 C Fe2O3 MnO Al2O3

mg/100 g %

C0rr 0–3 101.92 6.4 1.86 0.17 0.002 0.006

Ah 15–20 17.36 9.3 0.12 0.10 0.003 0.003

AhC 35–40 18.48 7.7 0.16 0.19 0.005 0.005

C1 55–60 2.24 4.3 0.08 0.11 0.005 0.005

C2 75–80 1.12 8.2 0.21 0.32 0.008 0.008

C2 95–100 0.57 10.5 0.11 0.12 0.005 0.005

Table 3. The characteristic pH, total acidity, and sorption�capacity of the soils (for absolutely dry weighed portions)

Hori�zon

Depth, cm

pH Hydrolytic acidity Exchange�able Ca2+

Exchange�able Mg2+

Cation exchange capacity Base saturation,

%water salt mg�equiv/100 g

C0rr 0–3 6.3 5.6 1.01 4.0 2.0 7.01 85.6Ah 15–20 6.9 6.0 0.55 4.0 2.8 7.35 92.5AhC 35–40 6.7 5.7 1.08 5.2 2.4 8.68 87.6C1 55–60 6.7 5.9 0.59 4.8 2.0 7.39 92.0C2 75–80 6.4 5.4 1.72 6.4 1.6 9.72 82.3C2 95–100 6.6 5.8 0.67 4.8 1.2 6.67 90.0



At the test plot, the ground water was revealed bydrilling at a depth of 5.8–7.7 m. It is characterized bya high content of NaCl and an increased content ofpotassium and bromine. It may be assumed that theareas of the petroleum storage depot and the adjacentstores were used not only for oil products but also forcommon salt and fertilizers. Taking into considerationthe light texture of the soils of the experimental plot,the water infiltration into them should be quick andcomplete. This is not the case, because the groundwa�ter is close to the surface in the spring, summer, andautumn.

METHODS

The content and composition of the oil hydrocar�bons in the soils were determined at Yugorsk StateUniversity with the use of standard equipment (aClarus 500MS device produced by the Perkin Elmerfirm with the Turbomass Gold program).

A preliminary survey (2006) and monitoring (2007)were performed in the field. The preliminary surveywas aimed at the determination of the taxonomic posi�tion and the agrochemical properties of the soils andthe composition of the oil polluting the area in order tochoose the reclamation measures. The soils of the testplot were sampled by drilling with their simultaneousmorphological description. For this purpose, we chosean area with the slightest oil contamination in order toexclude the effect of the oil’s chemical properties onthe analytical data on the soils. The chemical soilproperties were determined in dried and sieved(through a 1�mm screen) samples with the use of con�ventional methods [1]. The analysis was performed inTomsk at the laboratory of the Institute of Monitoringof Climatic and Ecological Systems of the SiberianBranch of the Russian Academy of Sciences.

For monitoring the soils at the test plot, they weresampled according to State Standard 17.4.4.02�84.The samples were taken using a hand columnar sam�pler. A joint sample was made of six single samples.Samples were taken from the 0� to 20� and 20� to40�cm�thick soil layers in the open areas and underthe constructions. Under the box for metal barrels, thedistance between the soil’s surface and the metal coverunder the barrels is sufficient for the soil sampling byvertical drilling. Under the reservoir set on the surface,samples were taken by a sampler at inclined drilling. Inthis case, the sampling depth is conventional, and thesampling of the required soil layer is the main task.

The samples were taken in three periods. The initialconcentration of the oil products in the soils of the testplot was determined in a mixed sample taken at theexperiment’s start on June 16, 2007. Intermediatesampling was performed on the 45th day of the adsor�bent’s exposition (July 28, 2007), and the final one wasperformed after 131 days (October 22, 2007). Theareas under the constructions and the open areas aredivided into two parts. Pure adsorbent (PS) was placed

into the perforated pipes in the first part, and a similaradsorbent with the HCRM culture was used in the sec�ond part.

Samples for the chemical analysis (1 kg) were takenfrom the joint sample in a random way. They wereplaced into a special plastic package chemically inertto HC. Then, the samples were air dried, crushed, anduniformly mixed. A weighed portion was taken fromeach sample and used for the gravimetric determina�tion of the oil hydrocarbons.

The substances were extracted by n�hexane [3]. Itwas added to the weighed soil sample (about 50 g) inthe amount of 40 ml and shaken for 5 minutes. Themixture was allowed to set for one hour, and an aliquotof the extract was poured into a graduated cylinder.The extraction was repeated with the same amount ofsolvent. The aliquots were poured and their total vol�ume was measured. The obtained total aliquot wasdewatered using anhydrous sodium sulfate; then, thesolvent was evaporated using a rotation evaporator to avolume of 1 ml at a temperature of 40°С. The remain�ing solvent was blown out using a nitrogen flow atroom temperature, and the amount of the oil productswas determined using the gravimetric method.

The composition of the n�alkanes in the soils wasdetermined. The compositions of the other hydrocar�bons (isoprenoids, in particular) did not significantlychanged in the short time period, so they were notstudied [7]. The sample was chromatographed with theuse of an Elite�1 capillary column 30 m × 0.32 mm ×0.25 µm in size with a temperature programmingregime from 40 to 260°С at a heating rate of 5°/min.The rate of the further temperature increase up to330°C was 8°/min, and helium was used as the carriergas. The temperature of the electron source of themass spectrometer was 250°С.

RESULTS OF THE EXPERIMENT

One of the main tasks of the CLEANSOIL Projectis to study the possibility of the use of a local adsorbentfor soil purification from HCs. The Irvelen polymerfibers are characterized by the best adsorption of satu�rated and aromatic HCs among all the local adsor�bents. Irvelen fibers (produced by the RUNO+ enter�prise in Tomsk) are made from waste products andtheir price is acceptable, which is also an indispensablecondition of the CLEANSOIL program.

The initial content of oil products shows that thesoil contamination at the test plot was very nonuni�form (Table 4). The content of oil products under theconstructions is several times higher as compared tothe open areas and rises considerably with the depth.Under the constructions, the HC content drops by7.3–12.4% in the case when the pure (withoutHCRM) adsorbent was exposed for 45 days(28.07.2007). The rate of the soil purification from theHCs is low for the top layer (7.3 mg/kg per day) andrises up to 25.5 mg/kg per day at a depth close to the

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ZAKHARCHENKO et al.

adsorbent. It may be concluded that the soil purifica�tion by the pure adsorbent placed into the soil drainagepipes is slight.

The presence of the HCRM in the adsorbentenhances the soil purification and provides a drop inthe content of the oil products by 51.5% in the 0� to20�cm�thick layer and by 58.2% in the 20� to 40�cm�thick layer. The presence of HCRM in the adsorbentsignificantly increases the purification rate of soilsfrom HCs under constructions: up to 59.5 mg/kg perday in the 0� to 20�cm�thick layer and up to 115 mg/kgper day in the 20� to 40�cm�thick layer, which is closerto the adsorbent with HCRM.

After adsorbent’s exposition for 131 days, the situ�ation changes. In the summer, the drop in the HCcontent under the constructions in the places wherethe HCRM was absent is insignificant, while, in theautumn, the relative drop in the content of the oilproducts rises to 51.9% in the 0� to 20�cm�thick layerand to 95.9% in the 20� to 40�cm�thick layer. Thehighest rate—87 mg/kg per day—was recorded.

In the open part of the test plot, the content of theoil products drops sharply with the depth. In the openarea without the HCRM, the content of the HCs ofthe oil products within the first 45 days of the adsor�bent’s exposition drops insignificantly (by 22%) in the0� to 20�cm�thick layer and even rises (–24.4%) at adepth of 20–40 cm. A rise in the HC content due tothe inflow of new HC portions is impossible, becausethis is controlled according to the experimental condi�tions. Part of the HCs probably migrates from the 0� to20�cm�thick layer into the 20� to 40�cm�thick one.

In case of the HCRM’s presence, the relative vari�ations are more significant. The change in the HCcontent increases to 60.3% at a depth of 20–40 cm

near the adsorbent with the HCRM. The purificationrates from the HCs in the open areas are lower as com�pared to those in the areas under the constructions.

In the autumn, the entire test plot was flooded byrainwater, so the last soil samples (on the 131st day ofthe exposition) were taken in the open part of the testplot without consideration for the HCRM’s presenceor absence. The data obtained on the content of the oilproducts show the final drop of the pollutant contentwithin the summer period in the open part of the testplot, although the HC reduction rates are insignificant(0.05 mg/kg per day in the 0� to 20�cm�thick layer and5.4 mg/kg per day in the 20� to 40�cm�thick layer).

The purification of the test plot contaminated byoil is confirmed by the changes in the oil compositionin the soil. A wide range of n�alkanes is revealed in thesoil samples taken prior to the experiment’s start in2006. This points to the fact that crude oil was spilledamong the other oil products in 2002 (Table 5). Theabsolute content of the n�alkanes was calculated as arelative one, and the isoprenes were excluded for theconvenient comparison of the composition.

The content of the HCs was determined in thesamples taken in July. They were affected by theHCRM for 45 days. In the 0� to 20�cm�thick layer ofthe open area, the part of the n�alkanes with chains upto С14 among soil the HCs and the part of the high�molecular n�alkanes with С31–С40 dropped. Part ofthe high�molecular С30–С40 components dropped inparallel with the distance from the HCRM source (inthe 20� to 40�cm�thick layer). The content of C29 andC27 increases considerably. When HCRM are used inthe soil samples taken under the constructions fromthe 20� to 40�cm�thick layer, high�molecular normalС26–С40 alkanes are absent, and the relative content of

Table 4. The effect of the exposition (for 45 and 131 days) of the pure adsorbent (PS) and the adsorbent with microorgan�isms (HCRM) in the open area and under the constructions on the HC content, the drop in the content in relation to thepreceding measurements, and the rate of the soil purification (in the 0� to 20�cm�thick layer above the line and in the 20�to 40�cm�thick layer under the line)

Adorbent Initial content, mg/kg

45 days of exposition 131 days of exposition

Content, mg/kg relative drop, % rate, mg/kg per day

Content, mg/kg relative drop, % rate,

mg/kg per day

Under the constructions

PS

HCRM

Open area

PS

HCRMNot det.

5374.59269.8�� 4980.2

8124.4�� 7.3

12.4�� 8.8

25.5�� 2396.8

579.4�� 51.9

92.9�� 30.0

87.7��

5203.18881.7�� 2526.1

3708.8�� 51.5

58.2�� 59.5

115.0�� 1715.2

3518.0�� 32.1

5.1�� 9.4

2.2��

1894.9806.8

�� 1477.81003.8�� 22.0

24.4–�� 0.5

0.5–�� 1473.6

539.1�� 0.3

46.3�� 0.05

5.4��

1614.1958.5

�� 1466.2380.6

�� 9.260.3�� 0.2

1.3��



the low�molecular С17–С21 n�alkanes is higher ascompared to the initial HCs distribution in the oil pol�lution.

In the 0� to 20�cm�thick layer, the composition ofthe С28–С40 n�alkanes also becomes less diverse. Boththe n�alkanes up to С14 and the very large moleculesundergo decomposition. The content of the medium�size n�alkanes increases.

DISCUSSION

The soil properties in the test plot permit one toimplement the remediation procedures after the soilcontamination with petroleum using oil�consumingmicroorganisms. The light soil texture creates water–air conditions favorable for microorganisms. Thegroundwater table is not deep, but the internal drain�age made of perforated pipes removes the excessivemoisture from the soil and serves as a source of oil�consuming microorganisms. They migrate moreintensively in more porous light�textured soils than inheavy�textured ones. Exchangeable hydrogen ispresent in the soil, but the weakly acid reaction favorsthe development of microorganisms. In addition,there are many nutrients in the soil (N, P, and K). Theelevated content of exchangeable Ca and Mg alsofavors the development of microorganisms and deter�mines the buffering properties of the soils in relation tothe substances forming at the HCs decomposition.The podzolic soils of the surrounding area are charac�terized by their more acid reaction (pH = 5 andlower), base saturation of 40–48%, and pHsalt for topthe horizons of 3.5–3.8 [4]. The content of exchange�able Ca2+ and Mg2+ is two times lower as compared tothe test plot. The poorly formed soil of the test plotcould not contain as much nitrogen, phosphorus, andadsorbed Ca and Mg, and this is a result of the techno�genic pollution of the area. The additional applicationof mineral fertilizers to the soils of the test plot was notrequired.

The drop in the HC content in the soil above theadsorbent with the microorganisms is greater as com�pared to the soil above the adsorbent without them.According to the published data [8, 11], the applica�tion of HC�reducing bacteria to soils contaminated byoil results in the destruction of about 30% of the oilHCs within 40 days and up to 70–75% within12 months.

The content of the oil HCs under the constructionsis higher by about an order of magnitude as comparedto the open area. The constructions were made prior tothe HC inflow to the soil; that is to say, the HCsappeared under the constructions as a result of theirhorizontal migration in the soil. This is the cause oftheir low�molecular composition and higher contentas compared to the open areas. For example, the HCcontent in the 0� to 20�cm�thick layer is 5374.5 mg/kgunder the constructions and 1894.9 mg/kg in the openarea. The difference is especially great in the 20� to 40�cm�

thick layer: 9269.8 and 806.8 mg/kg, respectively.Under the constructions, the HC distribution patternis inverse: the deeper the layer, the greater the content.The situation in the open areas is the opposite. Theregularities are similar in the areas with the HCRM’suse, which may be explained by two hypotheses.

Table 5. Relative changes in the composition of the n�al�kanes (% of the total area of the maximums) in the samplestaken in 2006 (without microorganisms) and after 45 days ofexposition of the adsorbent with the microorganisms in soilsof the test plot in June–July 2007 at two depths in the openarea and under the constructions

n�al�kanes

Without HCRM After the effect of the HCRM

open area open area under the con�structions

0–20 cm 0–20 cm 20–40 cm 0–20 cm 20–40 cm

n�C10 1.53 Absent

n�C13 5.20 ''

n�C14 6.40 ''

n�C15 6.67 0.68 1.69 3.50 3.88

n�C16 5.72 2.52 4.66 5.48 6.44

n�C17 6.11 3.76 5.504 6.81 8.92

n�C18 5.71 5.88 7.08 8.40 10.17

n�C19 4.26 5.88 6.35 10.44 12.85

n�C20 5.50 5.56 6.30 10.30 14.00

n�C21 3.81 4.42 5.59 5.57 8.51

n�C22 3.55 5.74 6.33 4.15 6.26

n�C23 3.32 5.65 4.76 8.03 11.10

n�C24 2.87 7.08 6.00 7.89 13.35

n�C25 2.96 10.55 6.24 6.61 4.52

n�C26 2.46 7.86 3.92 7.07 Absent

n�C27 1.93 16.07 15.41 15.75 ''

n�C28 2.04 6.83 9.90 Absent

n�C29 2.55 6.84 10.28 ''

n�C30 1.79 2.57 Absent

n�C31 2.37 1.08 ''

n�C32 2.16 ''

n�C33 2.25 1.04 ''

n�C34 2.50 ''

n�C35 2.43 ''

n�C36 2.61 ''

n�C37 2.83 ''

n�C38 2.86 ''

n�C39 2.78 ''

n�C40 2.82 ''

Total 100 100 100 100 100

460


ZAKHARCHENKO et al.

The first one is based on the soil’s saturation withoil at the spill. In this case, the HC amount enteringthe soil in the open area and under the constructions isalmost equal. Under the constructions, the HCsremain unchanged because of the insufficient mois�ture for their decomposition. In the open area, theHCs are decomposed, which results in their relativelyhigher content under the constructions. In the openarea, the HCs most available for the microorganismsare utilized first. In this case, the oil amount in the 0�to 20�cm�thick layer should be higher as compared tothe 20� to 40�cm�thick layer, but this is not the case.Therefore, the hypothesis of the thermodynamic oilmigration in the soil seems more probable.

The second hypothesis is related to the migration ofthe capillary moisture in the soil after the rainfallsfrom the open moistened areas to the drier soils underthe constructions. The flow of the film moisture mobi�lizes the pollutants, which may become rather con�centrated under the constructions. A thermodynamicgeochemical barrier is formed in the soil [9] due to thehorizontal gradient of the hydrothermal conditionsbetween the soils of the open area and those under theconstructions. This results in the HCs accumulationunder the constructions.

The high intensity of the HCs decompositionunder the constructions is seen not only in the soillayer closest to the adsorbent with the HCRM but alsoin the surface layer (Table 4). The decomposition’sintensity is from 51.5% in the 0� to 20�cm�thick layerto 55% in the 20� to 40�cm�thick layer. The capillaryforces under the constructions are one of the probablecauses of the HCRM’s transportation from the adsor�bent to the soil’s surface. This process could be studiedmore comprehensively if we had data on the HCscomposition under the constructions prior to theexperiment.

The study of the changes in the HC content revealsthe process of the oil’s destruction. The sample of 2006characterizes the HC composition at the beginning ofthe experiment after the crude oil spill. This sample ischaracterized by the uniform distribution of the HCswith respect to their chain length. After the 45�day�long exposition of the soils under HCRM’s effect, theHCs with chains smaller than С15 disappear. Accord�ing to [10], the composition of the methane–naph�thenic fractions is characterized by a sharp drop in thepart of the long�chain n�alkanes, which are probablythe most preferable substrate for the biochemicaltransformation.

The HC compositions of the soils in the open areasand under the constructions differ considerably. In theopen areas, n�alkanes with HC chains of more thanС27 are present in the soil. At a depth of 20–40 cm, thegreatest accumulation is typical for the n�alkanes withchains of С27, С28, and С29.

Under the constructions, the reduction of thehigh�molecule oil part is even more advanced: nearthe HCRM source (the 20� to 40�cm�thick layer), all

the HC chains more of than C25 are reduced. Twomaximums of the HCs with chains of C23–C24 andC19–C20 accumulation are revealed. Near the surface(the 0� to 20�cm�thick layer), the n�alkanes withchains of more than C27 are reduced, and the maxi�mum relative accumulation of the C27, C19, and C20 isrevealed. The use and accumulation of the remaindersis typical for the C15–C25 range, which is seen from theHC composition at a depth of 20–40 cm under theconstructions. Therefore, the initial HC compositionin the soil and the HCs assimilation by the microor�ganisms under the constructions differ from those inthe open area. Here, the greatest accumulation is typ�ical for the chains with an odd amount of carbonatoms, which is not the case under the constructions.

On the 45th day of the exposition, a local minimumin the C21 content was revealed in the open areas andunder the constructions. The curve of the C21 content(the C22 content under the constructions at a depth of20–40 cm) in relation to the composition of the n�alkanes is divided into two parts with their own modes.According to other data [10], odd n�alkanes are morepreferable for microorganisms. The polymodal distri�bution pattern of the HC content with respect to thecomposition of the n�alkanes caused by the microbialdestruction is explained by the diversity of the system�atic groups of microorganisms in the HCRM cultureand the different ways of the oil’s reduction and theHCs assimilation.

CONCLUSIONS

(1) The test plot is characterized by light�texturedsediments, a slightly acid reaction, an elevated contentof available nitrogen and phosphorus, a not deepgroundwater table, and the presence of artificial mate�rial drainage. The soil exchange complex containsCa2+ and Mg2+. All these factors create favorable min�eral nutrition and hydrophysical conditions in the soilsfor the oil�assimilating microorganisms.

(2) It has been revealed that, at the use of theCLEANSOIL technology with oil�assimilatingmicroorganisms, the soil purification from oil HCs ismore effective under the constructions, where it isseen in the entire soil layer, while, in the open areas, adrop in the HC content is only seen in the layer closeto the adsorbent with the microorganisms.

(3) The soil purification from oil by the pure adsor�bent set at a depth of 60 cm in the perforated pipes isnot revealed.

(4) The oil�assimilating microorganisms activelyutilize the HCs with С14 and smaller chains andchange the composition of the oil products. The con�tent of high�molecular HCs (С32–С40) decreases withthe depth, and the chains of n�alkanes under the con�structions become shorter.

(5) The CLEANSOIL technology for soil purifica�tion of oil products in situ may only be used for soils oflight texture at the addition of hydrocarbon�reducing



microorganisms to the adsorbent and with sufficientmineral nutrition.

REFERENCES

1. E. F. Arinushkina, Manual on the Chemical Analysis ofSoils (Izd. Mosk. Gos. Univ., Moscow, 1970) [in Rus�sian].

2. O. K. Bazhenova, Yu. K. Burlin, B. A. Sokolov, andV. E. Khain, Geology and Geochemistry of Oil and Gas(Izd. Mosk. Gos. Univ., Moscow, 2004) [in Russian].

3. Yu. S. Drugov and A. A. Rodin, Ecological Analysisupon Accidental Oil Spills (St. Petersburg, 2000) [inRussian].

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10. T. A. Odintsova, “Ecological and Geochemical Aspectsof the Transformation of Organic Matter in Oil�Pol�luted Geosystems,” in Modeling of the Strategy of theDevelopment of Georesources (Gornyi Inst. Ural’sk.Otd. Ross. Akad. Nauk, Perm, 2003), pp. 241–245 [inRussian].

11. O. B. Soprunova, O. S. Sangadzhieva, and M. A. Klyu�yanova, “Experimental Study of the Biological Purifi�cation of Soils by the Growing Microbial Culture,”Ekologich. Sist. Pribory No. 11, 12–15 (2004).

12. Technologies of the Remediation of Soils Polluted with Oiland Oil Products. Reference Manual (REFIA NIA�Priroda, Moscow, 2001) [in Russian].

13. A. G. Shapar’, O. K. Tyapkin, N. A. Emets, andO. A. Skripnik, “Major Technical Solutions upon theDesign of the Experimental Polygon for Purification ofSoils Contaminated with Pesticides,” Materials of the4th Int. Conf. Waste Management and Utilization(Kharkov, 2007) [in Russian].

14. I. I. Shilova, “The Biological Remediation of Oil�Pol�luted Soils in the Taiga Zone, in Remediation of Oil�Pol�luted Soil Ecosystems (Moscow, 1988), pp. 159–168 [inRussian].

15. A. G. Shapar, O. A. Skrypnyk, O. K. Tyapkin, andN. A. Yemets, “Some Results of Soil Pesticides Removalin Ukrainian Part of the EU Project CLEANSOIL—AnInnovative Method for the On�Site Remediation ofPolluted Soil Under Existing Infrastructures,” Int.Symp. “Euro�ECO�Hanover 2009” Environmental,Engineering, Economic and Legal Aspects for SustainableLiving (2009).

remediation of oil-contaminated soil using the cleansoil technology

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