Bioremediation of hydrocarbon-contaminated polar soils

Bioremediation is increasingly viewed as an appropriate remediation technology for hydrocarbon-contaminated polar soils. As for all soils, the successful application of bioremediation depends on appropriate biodegradative microbes and environmental conditions in situ. Laboratory studies have confirmed that hydrocarbon-degrading bacteria typically assigned to the genera Rhodococcus, Sphingomonas or Pseudomonas are present in contaminated polar soils. However, as indicated by the persistence of spilled hydrocarbons, environmental conditions in situ are suboptimal for biodegradation in polar soils. Therefore, it is likely that ex situ bioremediation will be the method of choice for ameliorating and controlling the factors limiting microbial activity, i.e. low and fluctuating soil temperatures, low levels of nutrients, and possible alkalinity and low moisture. Care must be taken when adding nutrients to the coarse-textured, low-moisture soils prevalent in continental Antarctica and the high Arctic because excess levels can inhibit hydrocarbon biodegradation by decreasing soil water potentials. Bioremediation experiments conducted on site in the Arctic indicate that land farming and biopiles may be useful approaches for bioremediation of polar soils.     

土壤中高环多环芳烃微生物降解的研究进展

微生物修复是去除土壤中多环芳烃(PAHs)的主要措施。本文以微生物修复PAHs污染土壤的理论基础及其难点为主线,全面综述了土壤中高环PAHs的微生物降解机理。近年来,富集分离得到的以高环PAHs为唯一碳源和能源的优势降解菌逐渐增多,其中,主要是代谢降解四环PAHs的单株降解菌,一些降解菌还能以共代谢方式利用五环PAHs。高环PAHs污染土壤修复的一个难点是其低生物可利用性,微生物通过释放生物表面活性剂、形成生物膜以及分泌胞外多糖提高高环PAHs的生物可利用性,从而加速其降解。真菌和细菌联合作用能增强污染土壤实地修复的效果。因此,通过微生物修复技术来去除土壤中PAHs具有环境友好性、经济适用性以及可持续应用性。     

Bioventing soils contaminated with petroleum hydrocarbons

Summary Bioventing combines the capabilities of soil venting and enhanced bioremediation to cost-effectively remove light and middle distillate hydrocarbons from vadose zone soils and the groundwater table. Soil venting removes the more volatile fuel components from unsaturated soil and promotes aerobic biodegradation by driving large volumes of air into the subsurface. In theory, air is several thousand times more effective than water in penetrating and aerating fuel-saturated and low permeability soil horizons. Aerobic microbial degradation can mitigate both residual and vapor phase hydrocarbon concentrations. Soil venting is being evaluated at a number of U.S. military sites contaminated with middle distillate fuels to determine its potential to stimulate in situ aerobic biodegradation and to develop techniques to promote in situ vapor phase degradation. In situ respirometric evaluations and field pilot studies at sites with varying soil conditions indicate that bioventing is a cost-effective method to treat soils contaminated with jet fuels and diesel.     

Toward the bioremediation of dioxin-polluted soil: structural and functional analyses of in situ microbial populations by quinone profiling and culture-dependent methods

In order to obtain basic information toward the bioremediation of dioxin-polluted soil, microbial communities in farmland soils polluted with high concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were studied by quinone profiling as well as conventional microbiological methods. The concentration of PCDD/Fs in the polluted soils ranged from 36 to 4,980 pg toxicity equivalent quality (TEQ) g(-1) dry weight of soil. There was an inverse relationship between the levels of PCDD/Fs and microbial biomass as measured by direct cell counting and quinone profiling. The most abundant quinone type detected was either MK-6 or Q-10. In addition, MK-8, MK-8(H2), and MK-9(H8) were detected in significant amounts. Numerical analysis of quinone profiles showed that the heavily polluted soils (> or = 1,430 pg TEQ g(-1)) contained different community structures from lightly polluted soils (< or = 56 pg TEQ g(-1)). Cultivation of the microbial populations in the heavily polluted soils with dibenzofuran or 2-chlorodibenzofuran resulted in enrichment of Q-10-containing bacteria. When the heavily polluted soil was incubated in static bottles with autoclaved compost as an organic nutrient additive, the concentrations of PCDD/Fs in the soil were decreased by 22% after 3 months of incubation. These results indicate that dioxin pollution exerted a significant effect on microbial populations in soil in terms of quantity, quality, and activity. The in situ microbial populations in the dioxin-polluted soil were suggested to have a potential for the transformation of PCDD/Fs and oxidative degradation of the lower chlorinated ones thus produced.     

Prepared Bed Land Treatment of Soils Containing Diesel and Crude Oil Hydrocarbons

An ex situ, field-scale, prepared bed land treatment unit (LTU) was used to bio-remediate soils containing petroleum hydrocarbons. Two soils were treated in side-by-side units to compare performance: (1) a clayey silt containing crude oil hydrocarbons from releases 30 to 40 years ago and (2) a silty sand containing diesel fuel hydrocarbons from a leak about three years prior to the bioremediation. The effectiveness of the bioremediation in the LTU was evaluated over a period of 18 months. The results indicated that: (1) prepared bed bioremediation reduced the hydrocarbon concentration, mobility, and relative toxicity in the soil with the diesel fuel, and (2) chemical bioavailability appeared to limit bioremediation of the soil containing the crude oil hydrocarbons. Although the soils containing the crude oil hydrocarbons contained an average of 10,000?mg TPH/kg dry soil, these soils had limited hydrocarbon availability, nontoxic conditions, and low potential for chemical migration. For the soils containing the diesel fuel, active prepared bed bioremediation of about 15 weeks was adequate to reach an environmentally acceptable endpoint. At that time, there was little further TPH loss, no Microtox^TM toxicity, and limited hydrocarbon mobility.     

Bacterial biosurfactant increases ex situ biodiesel bioremediation in clayey soil

The contamination of soils by oily compounds has several environmental impacts, which can be reversed through bioremediation, using biosurfactants as auxiliaries in the biodegradation process. In this study, we aimed to perform ex situ bioremediation of biodiesel-contaminated soil using biosurfactants produced by Bacillus methylotrophicus. A crude biosurfactant was produced in a whey-based culture medium supplemented with nutrients and was later added to biodiesel-contaminated clayey soil. The produced lipopeptide biosurfactant could reduce the surface tension of the fermentation broth to 30.2 mN/m. An increase in the microbial population was observed in the contaminated soil; this finding can be corroborated by the finding of increased CO₂ release over days of bioremediation. Compared with natural attenuation, the addition of a lower concentration of the biosurfactant (0.5% w/w in relation to the mass of diesel oil) to the soil increased biodiesel removal by about 16% after 90 days. The added biosurfactant did not affect the retention of the contaminant in the soil, which is an important factor to be considered when applying in situ bioremediation technologies.

     

Release Of Petroleum Hydrocarbons From Bioremediated Soils

This article presents a qualitative evaluation of the extent to which the bioavailability (release) of a chemical is related to the biodegradation of hydrocarbons in a field bioremediation unit. The objectives of this research were to (1) quantify the rate of release of petroleum hydrocarbons from two soils that were bioremediated, (2) explore hydrocarbon release as a process affecting bioremediation; and (3) investigate the impact of bioremediation on chemical release in the two soils. An experimental protocol was used to quantify the rate of release of these hydrocarbons from two soils that had been bioremediated in a field-scale prepared bed land treatment unit. One soil showed little change in hydrocarbon concentration during 55 weeks of prepared bed bioremediation. The field study results indicated that, prior to the bioremediation, this soil had reached an environmentally acceptable endpoint. The second soil showed considerable hydrocarbon loss as a result of the bioremediation. The rate of hydrocarbon release was determined for the first soil and for the second soil at time zero and after 1, 2, and 7 months of prepared bed bioremediation. The results indicated: (1) the fraction (F) of the specific hydrocarbons that were released rapidly from the soil and the rates of release (k₂) of the residual hydrocarbons that were released slowly, (2) that the mass of each chemical of concern that was released from the first soil was very low; and (3) that the hydrocarbon released rapidly from the second soil decreased as treatment progressed. The experiments also verified, qualitatively, that some portion of each chemical evaluated was not able to be released, and thus was unavailable for bioremediation in the prepared bed land treatment unit.     

Rhamnolipid-Enhanced Mineralization of Phenanthrene in Organic-Metal Co-Contaminated Soils

Successful remediation of soils co-contaminated with organics and metals may require a combination of technologies. This research addresses the organic component within co-contaminated sites. It is well known that metal contaminants in soil can partially or completely inhibit normal heterotrophic microbial activity and hence prevent in situ biodegradation of organics. Previous work has shown that a rhamnolipid biosurfactant can complex metals such as lead and cadmium. It has also been demonstrated, in pure culture, that rhamnolipid can mitigate metal inhibition during the degradation of naphthalene. The goal of this study was to investigate whether rhamnolipid could reduce the toxicity of a model metal, cadmium, to indigenous soil populations in two different soils, Brazito and Gila, during the mineralization of phenanthrene. Results show that cadmium inhibited phenanthrene mineralization in both soils at bioavailable cadmium concentrations as low as 27 µM. This inhibition was reduced by the addition of rhamnolipid. Since rhamnolipid is degraded by soil populations, a rhamnolipid pulsing strategy was used to maintain a constant level of rhamnolipid in the system. Using this strategy, phenanthrene mineralization levels comparable to the control (0 mM Cd/0 mM rhamnolipid) were achieved in the presence of toxic cadmium concentrations. This research demonstrates that pulsed application of rhamnolipid may allow bioremediation of organic contaminants in sites that are co-contaminated with organics and metals.     

The effect of the bioremediation of soil contaminated with petroleum derivatives on the occurrence of epigeic and edaphic fauna

This field study investigated the colonization process of soil contaminated with different petroleum products (petrol, diesel fuel, spent engine oil; dose: 6000 mg of fuel·kg^?1 dry mass [d.m.] of soil) by epigeic and edaphic invertebrates during the progress of natural bioremediation and bioremediation enhanced using selected microorganisms (ZB-01 biopreparation). Epigeic fauna was captured using pitfall traps. Occurrence of edaphic fauna in soil samples as well as total petroleum hydrocarbon contents (TPH) were also investigated. Results showed that inoculation with ZB-01 biocenosis allowed the degradation of petroleum derivatives in the soil contaminated with diesel fuel and engine oil, with 82.3% and 75.4% efficiency, respectively. Applying bioremediation to all contaminated soils accelerated the process of recolonization by edaphic invertebrates. However, the 28-month period was too short to observe full population recovery in soils contaminated with diesel fuel and engine oil. Microbe-enhanced bioremediation accelerated recolonization by epigeic invertebrates on soil contaminated with diesel fuel, whereas it exerted inhibitory effect on recolonization of soil contaminated with engine oil (especially by Collembola). The observed discrepancies in the rates of recolonization for soils contaminated with petrol and diesel fuel that were still noted at the stage of no longer different TPH levels justify the idea to include the survey of edaphic faunal density as one of the parameters in the ecological risk assessment of various bioremediation techniques.     

Nonreductive Biomineralization of Uranium(VI) Phosphate Via Microbial Phosphatase Activity in Anaerobic Conditions

The remediation of uranium from soils and groundwater at Department of Energy (DOE) sites across the United States represents a major environmental issue, and bioremediation has exhibited great potential as a strategy to immobilize U in the subsurface. The bioreduction of U(VI) to insoluble U(IV) uraninite has been proposed to be an effective bioremediation process in anaerobic conditions. However, high concentrations of nitrate and low pH found in some contaminated areas have been shown to limit the efficiency of microbial reduction of uranium. In the present study, nonreductive uranium biomineralization promoted by microbial phosphatase activity was investigated in anaerobic conditions in the presence of high nitrate and low pH as an alternative approach to the bioreduction of U(VI). A facultative anaerobe, Rahnella sp. Y9602, isolated from soils at DOE's Oak Ridge Field Research Center (ORFRC), was able to respire anaerobically on nitrate as a terminal electron acceptor in the presence of glycerol-3-phosphate (G3P) as the sole carbon and phosphorus source and hydrolyzed sufficient phosphate to precipitate 95% total uranium after 120 hours in synthetic groundwater at pH 5.5. Synchrotron X-ray diffraction and X-ray absorption spectroscopy identified the mineral formed as chernikovite, a U(VI) autunite-type mineral. The results of this study suggest that in contaminated subsurfaces, such as at the ORFRC, where high concentrations of nitrate and low pH may limit uranium bioreduction, the biomineralization of U(VI) phosphate minerals may be a more attractive approach for in situ remediation providing that a source of organophosphate is supplied for bioremediation.     

Copper uptake and phytotoxicity as assessed in situ for durum wheat (Triticum turgidum durum L.) cultivated in Cu-contaminated, former vineyard soils

This work assessed in situ, copper (Cu) uptake and phytotoxicity for durum wheat (Triticum turgidum durum L.) cropped in a range of Cu-contaminated, former vineyard soils (pH 4.2–7.8 and total Cu concentration 32–1,030 mg Cu kg⁻¹) and identified the underlying soil chemical properties and related root-induced chemical changes in the rhizosphere. Copper concentrations in plants were significantly and positively correlated to soil Cu concentration (total and EDTA). In addition, Cu concentration in roots which was positively correlated to soil pH tended to be larger in calcareous soils than in non-calcareous soils. Symptoms of Cu phytotoxicity (interveinal chlorosis) were observed in some calcareous soils. Iron (Fe)–Cu antagonism was found in calcareous soils. Rhizosphere alkalisation in the most acidic soils was related to decreased CaCl₂-extractable Cu. Conversely, water-extractable Cu increased in the rhizosphere of both non-calcareous and calcareous soils. This work suggests that plant Cu uptake and risks of Cu phytotoxicity in situ might be greater in calcareous soils due to interaction with Fe nutrition. Larger water extractability of Cu in the rhizosphere might relate to greater Cu uptake in plants exhibiting Cu phytotoxic symptoms.     

Do ammonia-oxidizing archaea respond to soil Cu contamination similarly asammonia-oxidizing bacteria?

Inhibitory experiments were conducted to investigate the responses of the population sizes of ammonia-oxidizing archaea (AOA) and bacteria (AOB) and the potential nitrification rates (PNRs) to Cu contamination in four Chinese soils. PNR was determined using a substrate-induced nitrification (SIN) assay, and the population size of the nitrifiers represented by amoA gene abundances was quantified using a real-time polymerase chain reaction (qPCR) assay. Both population size and PNR of the ammonia oxidizers reduced considerably at high Cu concentrations in all the soils. Bacterial amoA gene abundance was reduced by from 107-fold (Hailun soil) to more than 232-fold (Hangzhou soil) at the highest Cu concentrations (2,400 mg kg^?1 Cu for Hailun, Langfang and Guangzhou soils and 1,600 mg kg^?1 Cu for Hangzhou soil), while reduction in archaeal amoA gene abundance was from 10-fold (Langfang soil) to 89-fold (Hangzhou soil). AOA seemed more tolerant to Cu contamination than AOB. Nitrification rates were inhibited by more than 50% at a Cu concentration of 600 mg kg^?1, and by more than 90% at the highest Cu concentrations in all soils. These results indicated that both AOA and AOB can be inhibited by toxic metals, highlighting the need to consider the role of AOA in nitrification in soils.     

Effects of soil amendment with different carbon sources and other factors on the bioremediation of an aged PAH-contaminated soil

Carbon supplementation, soil moisture and soil aeration are believed to enhance in situ bioremediation of PAH-contaminated soils by stimulating the growth of indigenous microorganisms. However, the effects of added carbon and nitrogen together with soil moisture and soil aeration on the dissipation of PAHs and on associated microbial counts have yet to be fully assessed. In this study the effects on bioremediation of carbon source, carbon-to-nitrogen ratio, soil moisture and aeration on an aged PAH-contaminated agricultural soil were studied in microcosms over a 90-day period. Additions of starch, glucose and sodium succinate increased soil bacterial and fungal counts and accelerated the dissipation of phenanthrene and benzo(a)pyrene in soil. Decreases in phenanthrene and benzo(a)pyrene concentrations were effective in soil supplemented with glucose and sodium succinate (both 0.2 g C kg⁻¹ dry soil) and starch (1.0 g C kg⁻¹ dry soil). The bioremediation effect at a C/N ratio of 10:1 was significantly higher (P < 0.05) than at a C/N of either 25:1 or 40:1. Soil microbial counts and PAH dissipation were lower in the submerged soil but soil aeration increased bacterial and fungal counts, enhanced indigenous microbial metabolic activities, and accelerated the natural degradation of phenanthrene and benzo(a)pyrene. The results suggest that optimizing carbon source, C/N ratio, soil moisture and aeration conditions may be a feasible remediation strategy in certain PAH contaminated soils with large active microbial populations.     

Metal accumulation in cattle raised in a serpentine-soil area: Relationship between metal concentrations in soil, forage and animal tissues

Soils developed on serpentine rocks contain high levels of heavy metals such as copper (Cu), nickel (Ni) and chromium (Cr), and are deficient in some macronutrients. The crops and pasture grown on these soils may accumulate high levels of metals, which constitute a potential health hazard for cattle. The aim of this study was to evaluate Cr, Ni and Cu accumulation in cattle raised in a serpentine area in Southwest Europe (Galicia, NW Spain). Samples of liver, kidney and muscle of 41 animals aged 8–12 months were collected at slaughter. Representative samples of soil and forage were taken from 10 farms. Samples were acid-digested and metal concentrations determined by ICP-MS (Cr and Ni) and ICP-AES (Cu). The concentrations of the metals in soils and forage were in the range of those found in serpentine soils in other areas. Accumulation of Cr in animal tissues was generally low and within the normal range. However, 20% of the animals had toxic levels of Ni in kidney and 32% of the animals had liver Cu levels above the acceptable range. Serpentine soils had a significant effect on Ni and Cu accumulation in cattle, and a relatively high percentage of the animals showed tissue levels of Ni and Cu indicative of risk of toxicity.     

Biodegradation of aged diesel in diverse soil matrixes: impact of environmental conditions and bioavailability on microbial remediation capacity

While bioremediation of total petroleum hydrocarbons (TPH) is in general a robust technique, heterogeneity in terms of contaminant and environmental characteristics can impact the extent of biodegradation. The current study investigates the implications of different soil matrix types (anthropogenic fill layer, peat, clay, and sand) and bioavailability on bioremediation of an aged diesel contamination from a heterogeneous site. In addition to an uncontaminated sample for each soil type, samples representing two levels of contamination (high and low) were also used; initial TPH concentrations varied between 1.6 and 26.6 g TPH/kg and bioavailability between 36 and 100 %. While significant biodegradation occurred during 100 days of incubation under biostimulating conditions (64.4–100 % remediation efficiency), low bioavailability restricted full biodegradation, yielding a residual TPH concentration. Respiration levels, as well as the abundance of alkB, encoding mono-oxygenases pivotal for hydrocarbon metabolism, were positively correlated with TPH degradation, demonstrating their usefulness as a proxy for hydrocarbon biodegradation. However, absolute respiration and alkB presence were dependent on soil matrix type, indicating the sensitivity of results to initial environmental conditions. Through investigating biodegradation potential across a heterogeneous site, this research illuminates the interplay between soil matrix type, bioavailability, and bioremediation and the implications of these parameters for the effectiveness of an in situ treatment.     

Benzene Degradation at a Site Amended with Nitrate or Chlorate

Aromatic hydrocarbons are widespread in nature and often contribute to the pollution of soils, sediments, and groundwater. The contamination of soil with mobile aromatic compounds, generally termed BTEX (benzene, toluene, ethylbenzene, xylene) is observed at many industrial sites, especially those associated with the petrochemical industry. In situ bioremediation of sites that are contaminated with BTEX can be applied both aerobically and anaerobically. The use of anaerobic in situ bioremediation is advantageous because supply of oxygen is not needed. Nevertheless, anaerobic in situ bioremediation is less commonly used for BTEX contaminated sites. This paper describes push-pull experiments in order to stimulate the degradation of benzene by the addition of nitrate or chlorate. Deuterated benzene was subjected with nitrate-amended groundwater to the aquifer, and the mineralization was traced by the enrichment of deuterium in the groundwater. Nitrate can be used as electron acceptor, and the addition of nitrate at a site in The Netherlands resulted in partial degradation of benzene. This was demonstrated by comparing various push-pull experiments, benzene concentration measurements, stable isotope analyses of benzene and water, and modeling. Chlorate can be used for the in situ production of oxygen, followed by degradation of benzene with oxygen as electron acceptor. The addition of chlorate at the site resulted in the complete removal of benzene demonstrating a complete degradation within 4 weeks. A pull phase was not needed during this run.     

Laboratory study on the bioremediation of petrochemical sludge-contaminated soil

This study evaluated by biological and chemical analyses the effectiveness of bioremediation of sludge from the petrochemical industry in systems containing artificially contaminated soil. The sludge–soil systems were prepared with three different initial concentrations of sludge, and during bioremediation 86–95% of the hydrocarbons was eliminated. Simultaneously, soil bacterial populations and inhibition of seed germination by aqueous extracts increased in all sludge–soil systems during the first 180 days of treatment. After 1 year of bioremediation, a loss in the catabolic capacity of the Gram-negative bacterial population was observed, but was not dependent on the initial sludge concentration. Furthermore, residual levels of hydrocarbons and seed germination inhibitory effect decreased sharply, but some level of toxicity remained in the systems containing the highest initial sludge concentration. Independent of the initial sludge concentration, the contaminated soils did not re-establish their original features even when residual hydrocarbon concentrations suggested the end of the process.     

Effects of humic substances and soya lecithin on the aerobic bioremediation of a soil historically contaminated by polycyclic aromatic hydrocarbons (PAHs)

The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) strongly reduces their bioavailability in aged contaminated soils, thus limiting their bioremediation. The biodegradation of PAHs in soils can be enhanced by employing surface-active agents. However, chemical surfactants are often recalcitrant and exert toxic effects in the amended soils. The effects of two biogenic materials as pollutant-mobilizing agents on the aerobic bioremediation of an aged-contaminated soil were investigated here. A soil historically contaminated by about 13 g kg(-1) of a large variety of PAHs, was amended with soya lecithin (SL) or humic substances (HS) at 1.5% w/w and incubated in aerobic solid-phase and slurry-phase reactors for 150 days. A slow and only partial biodegradation of low-molecular weight PAHs, along with a moderate depletion of the initial soil ecotoxicity, was observed in the control reactors. The overall removal of PAHs in the presence of SL or HS was faster and more extensive and accompanied by a larger soil detoxification, especially under slurry-phase conditions. The SL and HS could be metabolized by soil aerobic microorganisms and enhanced the occurrence of both soil PAHs and indigenous aerobic PAH-degrading bacteria in the reactor water phase. These results indicate that SL and HS are biodegradable and efficiently enhance PAH bioavailability in soil. These natural surfactants significantly intensified the aerobic bioremediation of a historically PAH-contaminated soil under treatment conditions similar to those commonly employed in large-scale soil bioremediation.     

Changes of chromium behavior in soil during phenanthrene removal by <Emphasis Type="Italic">Penicillium frequentans</Emphasis>

Soil contamination due to polycyclic aromatic hydrocarbons is often associated with the presence of high levels of potentially toxic metals. Bioremediation is an important option for the clean up of this type of contamination. Changes of chromium fluxes and concentrations during the phenanthrene removal by Penicillium frequentans in soil were investigated. During the bioremediation process, changes in chromium behavior were monitored by Diffusive Gradients in Thin-films (DGT) and by filtration in both sterilized and non-sterilized soils. DGT provided absolute data on fluxes from the solid phase and relative trends of concentrations of the most labile metal species. Filtration provided data on the concentrations of Cr in the solution phase. Together the data provided information about the physical and chemical metal behavior. Results showed that the highest phenanthrene removal was observed in non-sterilized soil (which included the autochthonous microorganisms and P. frequentans inoculum), with a phenanthrene removal of 73 ± 3.2%. However, in all cases microbial activity increased chromium fluxes and chromium soil solution concentration. The bioremediation of soil by P. frequentans increased the lability and mobility of chromium in soil, with potential consequences for plant uptake and for increased movement of metals into the human food chain. Published online December 2004     

Effect of activated charcoal on bioremediation of diesel fuel-contaminated soil

Elevated plant and microbial toxicity throughout the season was found in field experiments on bioremediation of diesel fuel (DF)-contaminated soil (4.5%). This was an indication of the presence of mobile toxic DF components and their metabolites. Introduction of granulated activated charcoal (GAC) was shown to decrease the bio- and phytotoxicity of petroleum-contaminated soil, resulting in a sharp increase in the abundance of petroleum degraders (both aboriginal and inoculated ones), as well as to create conditions for improved growth at the stage of post-treatment by phytoremediation. In spite of short-time deceleration of DF degradation, more complete decrease of hydrocarbon concentrations occurred in the presence of GAC, while simultaneous introduction of the sorbent and a biopreparation (and association of mesophilic petroleum-degrading strains) provided the best results. In these variants the concentration of petroleum hydrocarbons decreased to 0.19–0.21 and 0.13–0.14%, respectively, which was 1.5 and 2 times lower than the values for unsupplemented control. Thus, GAC introduction during bioremediation of DF-contaminated soils increases the efficiency of remediation and localizes the pollutants in the treated layer, which decreases the risk of their penetration into groundwater during in situ soil treatment.