Remediation Of Diesel-contaminated Soils Research Articles

Analyzing atmospheric plasma's potential for diesel soil remediation: Insightful mechanisms

The remediation of diesel-contaminated soil is a critical environmental concern, driving the need for effective solutions. Recently, the methodology of Non-thermal Atmospheric Plasma (NTAP) technology, which is equipped with a Dielectric Barrier Discharge (DBD) electrode and has become a feasible approach, was proven to be viable. The reactive species from the plasma were exposed to the contaminated soil in this investigation using the NTAP technique. The reacted soil was then extracted using dichloromethane, and the amount of Total Petroleum Hydrocarbon (TPH) removed was assessed. Investigation into varying power levels, treatment durations, and hydrogen peroxide integration revealed significant findings. With an initial concentration of 3086 mg of diesel/kg of soil and a pH of 5.0, 83% of the diesel was removed from the soil at 150 W in under 20 min. Extended exposure to NTAP further improved removal rates, highlighting the importance of treatment duration optimization. Additionally, combining hydrogen peroxide (H2O2) with NTAP enhanced removal efficiency by facilitating diesel breakdown. This synergy offers a promising avenue for comprehensive soil decontamination. Further analysis considered the impact of soil characteristics on removal efficacy. Mechanistically, NTAP generates reactive species that degrade diesel into less harmful compounds, aiding subsequent removal. Overall, NTAP advances environmental restoration efforts by offering a quick, economical, and environmentally benign method of remediating diesel-contaminated soil especially when used in tandem with hydrogen peroxide.

Remediation of Diesel-contaminated soil using zero-valent nano-nickel and zero-valent nano copper particles-stabilized Tween 80 surfactant foam

This paper uniquely reports the remediation of diesel-contaminated desert soil by aqueous Tween 80 (TW80) surfactant foams stabilized by zero–valent nickel (Ni0) and zero–valent copper (Cu0) nanoparticles (NPs). The sizes of synthesized nanoparticles, ∼21 nm (Cu0), ∼20 nm (Ni0), are determined by XRD and FE-SEM. The impact of these NPs (1 mg, 2 mg concentrations) on foaming characteristics, remediation of diesel-contaminated soils is explored at 2 vol% TW80 surfactant concentration. With 2 mg concentration of Ni0, Cu0 NPs and 2 vol% TW80 surfactant, it is found that 98.73 and 99.38 % diesel contaminants are removed.

Biosolids-derived biochar enhances the bioremediation of diesel-contaminated soil

Biochar, a low-cost carbonaceous product, is gaining relevance in the remediation of hydrocarbon-contaminated soil. Current literature has shown that biochar studies have been carried out under different conditions. Although some attempts have been made to assess the effect of varying conditions in biochar-based remdediation studies, no work has assessed the effect of biochar pyrolysis temperature, biochar dose, and fertiliser dose altogether on the efficacy of biosolids-derived biochar in the remediation of diesel-contaminated soil, despite the fact that the influence of these parameters on the efficacy of the remediation process are likely to be significant. This study aimed to investigate the effect of biosolids-derived biochar on the remediation and ecotoxicity of diesel-contaminated soil, as well as to assess the influence of biochar pyrolysis temperature, biochar dose, and fertiliser addition on soil remediation. After 12 weeks, the contaminated soil amended with biochar produced at 900 °C and applied at 10% together with 1% fertiliser had a TPH concentration lower than the EPA Victoria maximum threshold for Category D waste (5000 mg/kg); in contrast, the TPH concentration in the control exceeded this threshold. Further, soil ecotoxicity at week 12 was lower in most of the biochar treatments. The alkB gene copy numbers increased at week 12 in almost all treatments. Hydrocarbon removal and soil ecotoxicity was affected by the studied factors. This study demonstrated the potential of biosolids biochar as a low-cost treatment to enhance the bioremediation of diesel-contaminated soils, while showing the importance of the treatment conditions on the biochar efficacy in remediation.

Remediation of diesel-contaminated soil by alkoxyethanol aqueous two-phase system.

The increasing diesel pollution accidents pose a serious threat to the ecological environment and human health. Remediation of diesel-contaminated soil (DCS) has attracted widespread attention during the past few decades. This work proposed an approach for the remediation of DCS by alkoxyethanol aqueous two-phase extraction (ATPE), which was an application of this small molecule aqueous two-phase system (ATPS). In addition, the influence of temperature, stirring speed, stirring time, and solid-liquid ratio on the removal of diesel was explored respectively. The removal efficiency of diesel could reach more than 97.18% in 18min. Meanwhile, ATPS had high reusability, and the removal efficiency remained above 85.17% in the reuse process. Alkoxyethanol ATPE could effectively remove diesel hydrocarbons with different carbon chain lengths and the remediation process hardly caused residual organic solvents on the soil surface according to the analysis of gas chromatography-mass spectrometry (GC-MS) and Fourier transforms infrared (FT-IR), which could be regarded as the distinct advantage compared to the traditional surfactant washing method and organic solvent extraction method. The study of soil physicochemical properties and wheat germination proved that the soil structure and properties changed little after ATPE remediation. And finally, the mechanism of alkoxyethanol ATPE was intensively discussed according to the remediation characteristic. This work provided an efficient method for the remediation of DCS and widened the application fields of alkoxyethanol ATPS as well.

A comparative study of methods for remediation of diesel-contaminated soil

A comparative study of methods for remediation of diesel-contaminated soil

Effects of soil properties on the remediation of diesel-contaminated soil by Triton X-100-aided washing.

Although nonionic surfactant is widely used for petroleum-contaminated soil washing, there is no definite conclusion on the main soil factors which determine the removal of petroleum hydrocarbons from the soil. In this study, the influences of soil properties on Triton X-100-aided soil washing were investigated using 12 soils in China. The sorption characteristic of Triton X-100 on soils was described as well. The sorption isotherms of Triton X-100 on 12 typical soils were fitted to the Langmuir adsorption model, and the maximum sorption amount of Triton X-100 (Qmax) varied from 1.54 to 15.15mg/g. The removal rates of diesel for 12 soils were well fitted to the modified Michaelis-Menten equation, and the maximum removal rate of diesel (φmax) ranged from 62.92 to 90.36%. The correlation analysis indicated that the φmax is significantly correlated with the Qmax. The soil factors affecting diesel removal from soils followed the order of sand content > cation exchange capacity (CEC) > organic matter (OM) content > silt and clay content > SSA >> pH. The prediction model based on CEC, silt content, and pH explained 83.1% of variance of diesel removal from soils. This study will have important implication for successfully remediating organic-contaminated soil using nonionic surfactant-based soil washing.

Remediation of diesel-contaminated soil by low-temperature thermal desorption

Site contamination by petroleum hydrocarbons is a widespread environmental problem in the world. One of the methods used to cleanup petroleum compounds from contaminated soils is low-temperature thermal desorption (LTTD) that uses heat to evaporate volatile pollutants from the soil. The remediation of contaminated soil by diesel using the LTTD method was studied. The effect of temperature (180 and 340 °C), residence time (from 5 to 20 min) and soil texture (two different types containing sand, Bentonite clay and Kaolinite clay) was investigated. By using the LTTD method, the maximum removal efficiency of diesel from soil type A (30% sand, 50% Kaolinite, 20% Bentonite) was 95.6% at 340 °C during a period of 20 min. Moreover, the diesel removal rate was higher in samples containing a higher percentage of Kaolinite than of Bentonite. By applying a temperature range of 180–340 °C to soils contaminated by diesel with an initial concentration of 20,000 mg kg−1, the cleanup standards of diesel range organics contaminated soils can be achieved after 23 min. The costs of thermal remediation may be reduced by reusing the waste heat generated in several industries and may cover the required heat for the LTTD process and the selected range of temperature.

Remediation of Diesel-Contaminated Soil by Ultrasonic Solvent Extraction

Soil contamination by hydrocarbons is an environmental problem and its remediation is necessary. This work presents the effect of ultrasound on solvent extraction of soil contaminated with diesel fuel. For the experiments, the soil was contaminated with diesel (10% wt.). The remediation was carried out by ultrasonic solvent extraction and compared with Soxhlet extraction. The effect of different parameters (time, temperature, soil/solvent ratio and type of solvent) on removal efficiency was examined. With the aim to optimize the ultrasonic extraction, a Box–Behnken design under response surface methodology was used and the proposed model showed a good fit of the experimental data. The obtained results were compared with a conventional solvent extraction (Soxhlet) for both solvents (n-hexane and acetone). Moreover, the phytotoxic effect of soil after remediation treatment was observed on seed germination of Brassica rapa. The obtained results demonstrated that hexane was more effective than acetone in removing hydrocarbons from contaminated soil (80%), and the removal efficiency increased with the soil/solvent ratio (> 1:5) and reaction time (> 90 min). A second-order polynomial model was proposed to predict the removal efficiency of the extraction process.

A Low-Foaming and Biodegradable Surfactant as a Soil-Flushing Agent for Diesel-Contaminated Soil

A novel low-foaming and biodegradable surfactant, consisting of a nonionic head and acyl tail, was synthesized by the base-catalyzed additions of ethylene oxide and propylene oxide to oleic acid. The structure of the new surfactant was elucidated by 1H- and 13C NMR and FT-IR spectroscopies. Measured surface tension was approximately 35.1 mN/m, with a critical micelle concentration (CMC) of 0.026 mM. Both the viscosity and the foaming tendency were relatively low compared to the reported values of similar surfactants. These properties make this surfactant suitable as a cleaning agent for the purpose of remediation of diesel-contaminated soils via soil-flushing. Moreover, the biodegradability test showed that it was nearly completely removed (more than 95%) after seven days, suggesting it is indeed an environmentally-friendly detergent which is an important trait for any remediation reagents. Feasibility tests using diesel-contaminated soils demonstrated its superb potential as a soil-flushing agent to the level comparable to nonionic commercial products.

Effects of soil organic matter and ageing on remediation of diesel-contaminated soil

Bioremediation of diesel-contaminated soil was investigated for the effects of soil organic matter (SOM) and ageing time in two sets of experiments (Batch I and II, respectively). This study examined degradation efficiency in soil artificially contaminated with diesel oil (maximum total petroleum hydrocarbons (TPH) concentration of 9000 mg/kg soil). Batch I data showed that the values of the first-order degradation rate, k, were relatively high in the low-SOM soil batches. The quantity of SOM negatively correlated with the TPH degradation rates and with the total TPH degradation efficiency (%). Introduction of rhamnolipid to the soil proved to be a useful solution to resolve the problem of the residual TPH in the soil with high SOM. In Batch II, the k values decreased with the length of ageing time: 0.0245, 0.0128 and 0.0090 1/d in samples ST0 (freshly contaminated), ST38 (aged for 38 days) and ST101 (aged for 101 days), respectively. The TPH degradation efficiency (%) also decreased along with the ageing time. The research also applied molecular technology to analyse the bacterial community dynamics during the bioremediation course. Multivariate statistics based on terminal-restriction fragment length data indicated: 1) the soils with different SOM resulted in separate bacterial community structures, 2) ageing time created a variety of bacterial communities, 3) the bacterial community dynamics was associated with the hydrocarbon consumption. The SOM content in soils affected the TPH degradation rate and efficiency and the bacterial community structures. Aged soil is more difficult to remediate than freshly contaminated soil, and the resulting bacterial community was less dynamic and showed a lack of succession.

Remediation of Diesel-Contaminated Soils Using Persulfate Under Alkaline Condition

A laboratory study was conducted to assess the feasibility of remediating diesel-contaminated soils using sodium persulfate (SPS) oxidation under an alkaline pH. Lime (CaO) and sodium hydroxide (NaOH) were used as the alkaline sources, and various factors, including temperature, reaction time and concentration level, were investigated. Moreover, the combined usage of hydrogen peroxide (HP) and SPS in the presence or absence of NaOH was also studied. It was found that lime hydration resulted in rapid increases in pH (>12) and temperature (75 °C maximum) at a CaO/H2O mass ratio of 3/20. In the NaOH or CaO/SPS system, the maximum diesel degradation achieved was approximately 30 %. It was observed that using a larger amount of alkaline increased SPS decomposition and had almost no effect on diesel degradation. Limited solubilization of contaminants may have inhibited the effectiveness of alkaline-activated persulfate oxidation during the aqueous phase and hence resulted in incomplete diesel degradation. The highest rate of diesel degradation (i.e., 56 % in 7 days) was achieved using the dual oxidation system, in which a HP/SPS molar ratio of 3.3/0.5 was used. An aggressive oxidation process, coupled with HP, may enhance desorption of diesel from soils and allow oxidation to occur during the aqueous phase.

Potential of grasses and rhizosphere bacteria for bioremediation of diesel-contaminated soils

The techniques available for the remediation of environmental accidents involving petroleum hydrocarbons are generally high-cost solutions. A cheaper, practical and ecologically relevant alternative is the association of plants with microorganisms that contribute to the degradation and removal of hydrocarbons from the soil. The growth of three tropical grass species (Brachiaria brizantha, Brachiaria decumbens and Paspalum notatum) and the survival of root-associated bacterial communities was evaluated at different diesel oil concentrations. Seeds of three grass species were germinated in greenhouse and at different doses of diesel (0, 2.5, 5 and 10 g kg-1 soil). Plants were grown for 10 weeks with periodic assessment of germination, growth (fresh and dry weight), height, and number of bacteria in the soil (pots with or without plants). Growth and biomass of B. decumbens and P. notatum declined significantly when planted in diesel-oil contaminated soils. The presence of diesel fuel did not affect the growth of B. brizantha, which was highly tolerant to this pollutant. Bacterial growth was significant (p < 0.05) and the increase was directly proportional to the diesel dose. Bacteria growth in diesel-contaminated soils was stimulated up to 5-fold by the presence of grasses, demonstrating the positive interactions between rhizosphere and hydrocarbon-degrading bacteria in the remediation of diesel-contaminated soils.

Terrestrial microcosms in a feasibility study on the remediation of diesel-contaminated soils

Phytoremediation and bioremediation are site-specific processes, and feasibility studies should be performed as an initial step in scaling-up these processes. Soil microcosms can be a useful tool for investigating the efficiency of remediation alternatives under realistic conditions. In the present study, the degradation of diesel fuel in soil was studied in artificially assembled microcosms during a 180-day experiment. Microcosms consisted of soil columns seeded with a mix of Festuca arundinacea and Trifolium pratense into which earthworms were introduced and native soil microflora was used. Remediation assays were performed with different combinations of soil organisms' assemblages (micro-organisms, earthworms and plants) to determine the effects of these organisms and their interaction on diesel degradation. The microcosm system allowed for the study of the efficiency of remediation under field-relevant conditions. This system provided information about the dissipation of the pollutants as well as chemical leaching and possible toxic effects on the organisms during the remediation process. The decrease in soil hydrocarbon levels depended on the organisms' assemblage. Plants were not effective in the remediation of these soils despite their stimulation of microbial biomass. Conversely, earthworms had a beneficial impact on the dissipation of hydrocarbons that did not appear to be related to a generic improvement of plant or microbial activity. The grass species was more tolerant than the legume species to diesel fuel-contaminated soils. Leaching of hydrocarbons was negligible and independent of the organisms' assemblage.

Effect of metal oxides on the reactivity of persulfate/Fe(II) in the remediation of diesel-contaminated soil and sand

The effect of metal oxides on the ability of persulfate (PS) with Fe(II) to remediate diesel-contaminated soil was investigated. In both natural soil and purchased sand, the highest diesel degradation occurred at pH 3 and the optimum molar ratio of PS/Fe(II) was 100:1 (i.e. 500 mM PS to 5 mM Fe(II)). Moreover, adding Fe(II) increased PS reactivity more in soil than it did in sand, indicating the involvement of metal oxides in the soil matrix. Evaluating the effects of metal oxides (i.e. goethite, hematite, magnetite, and manganese oxide) on the reactivity of PS with/without Fe(II) in a system containing diesel-contaminated sand revealed that manganese oxide increased PS activity the most and that the highest diesel degradation by PS occurred when both manganese oxide and Fe(II) were used as activators. XRD did not show the transformation of manganese oxide in the presence of Fe(II). SEM-EDS showed the association of Fe(II) on the surface of manganese oxide, and ICP analysis revealed that almost all the added Fe(II) adsorbed to manganese oxide but almost none adsorbed to iron oxides under acidic conditions. Therefore, the high reactivity of PS could be due to the high density of Fe(II) over the surface of manganese oxide.

디젤오염토양의 TPH 분해를 위한 마이크로파의 가열특성

The application of microwave technology has been investigated in the remediation of diesel-contaminated soil. The paper deals with economic assessment by means of cost analysis and degradation characteristics at different microwave powers for total petroleum hydrocarbon (TPH) in diesel contaminated soils. The soils from S Mountain around the D University were sampled. The samples were screened with 2.0 mm mesh and dried for 6 hours before the diesel was added into the dried soils. The diesel-contaminated soil (3,300 mg THP/kg soil) was prepared with diesel (S Co.). The drying process was carried out in a microwave oven, a standard household appliance with a 2,450 MHz frequency and 700 W of power. The experiments were conducted from 0 to 20 minutes as the microwave powers increased from 350W to 500W to 700W. The concentrations of TPH were analysed using a gas chromatography/mass spectrometer (GC/MS). The initial concentration of TPH was 3,300 mg TPH/kg soil. The weight of contaminated soil was 200g. The concentration of TPH was decreased to 1,828 mg TPH/kg soil (44.7%), 1,347 mg TPH/kg soil (59.2%) and 1,014 mg TPH/kg soil (69.3%) at 350W, 500W and 700W for 15 minutes respectively. In addition, the curve was best fit with first order kinetics using the least-square method. The ranges of a first order rate constant k and r-square were <TEX>$0.0298{\sim}0.0375min^{-1}$</TEX> and <TEX>$0.9373{\sim}0.9541$</TEX> respectively.

Remediation of Diesel-Contaminated Soil Using Supercritical Carbon Dioxide and Ultrasound

The purpose of this study was to identify and evaluate the efficiency of the supercritical fluid extraction (SFE) method for removing diesel from an artificially contaminated soil using a supercritical carbon dioxide and an ultrasound. Compared with SFE, ultrasound-enhanced/assisted SFE (USFE) was able to provide a 14.8% increase in the diesel removal rate from diesel-contaminated soil at the SFE conditions of 40 °C, 16 MPa, 2 mL/min CO2 flow rate and 40 min dynamic extraction time, and the ultrasound conditions of 316 W/cm2 and 20 kHz. These results showed that an ultrasound reduce the extraction time, the extraction pressure, the CO2 flow rate and the extraction temperature during the SFE process by enhancing the mass transfer from the soil to the supercritical CO2.

2-09-04 Remediation of Diesel-Contaminated Soil using Supercritical Carbon Dioxide and Ultrasound(High power ultrasound)

2-09-04 Remediation of Diesel-Contaminated Soil using Supercritical Carbon Dioxide and Ultrasound(High power ultrasound)

A Laboratory and Pilot Study of Thermally Enhanced Soil Vapor Extraction Method for the Removal of Semi-Volatile Organic Contaminants

Laboratory and field pilot study was conducted to evaluate the effectiveness of thermally enhanced soil vapor extraction (SVE) system for the removal of semi-volatile organic contaminants (SVOCs) from soils. Several parametric studies were conducted to evaluate the effect of temperature and air flow rate on the removal of SVOCs. Column studies near ambient temperature show very little efficiency for SVOCs removal. The removal rates of SVOCs are highly dependent on temperature. Moving fronts in the effluent concentrations of contaminants are observed, according to the order of volatility of contaminant. This result is attributed to continuous changes in the liquid composition toward less volatile fractions, thus increasing the mole fraction of the less volatile fractions remaining in the liquid mixture. It is also found that increased air flow rate results in high removal rate of contaminants. However, too high air flow rate brings about the mass transfer limitation on the volatilization of the contaminants. Results from steady-state column studies show that mass transfer limitation is reduced at high temperature, possibly due to the increase in the diffusivity of contaminant in the liquid and gas phase. A field pilot study of a hot air injection method for the remediation of diesel-contaminated soil has shown advantages over the conventional SVE. Within 30 days of test operation, TPH concentrations at unsaturated soils were dramatically reduced, corresponding to more than 95% removal. However, temperature profiles and the removal rates of SVOCs near groundwater level indicate that moisture content would be a limiting factor in the real application of hot air injection.

A Central Composite Rotatable Analysis for the Catalyzed Hydrogen Peroxide Remediation of Diesel-Contaminated Soils.

A central composite rotatable design was used to investigate the interactions between hydrogen peroxide concentration, slurry volume, initial contaminant concentration, and soil organic carbon content in the catalyzed hydrogen peroxide remediation of diesel-contaminated soil. Two separate experimental matrices were investigated: (1) high slurry volumes and low peroxide concentrations, and (2) low slurry volumes with high peroxide concentrations. The time required for the high volume/low concentration system to proceed to completion was approximately three weeks; the low volume/high concentration reactions were complete within three days. The results showed that the soil organic carbon content was an insignificant variable in the catalyzed peroxide treatment of diesel-contaminated soils. However, significant interactions were found for the remaining three variables. The data were analyzed for total petroleum hydrocarbon (TPH) degradation and treatment stpichiometry. Although both systems could achieve equal levels of treatment, the stoichiometry of the high volume/low concentration system was significantly more efficient; therefore, the high volume/low concentration was determined to be the most economical system for the remediation of diesel-contaminated soils.