Diesel Fuel-contaminated Soil Research Articles

A full-scale bioremediation study of diesel fuel-contaminated soil: the effect of plant species and soil amendments

This article presents a comprehensive on-site bioremediation of an excavated diesel fuel-contaminated soil aided by various soil amendments and plant species. In the first 125 days, the excavated soil was placed in a land treatment unit, mixed with compost, and seeded with white clover (Trifolium repens). In the next 155 days, the land treatment unit was re-established and divided into four experimental plots. Experimental plots 2 and 3 were seeded with a mixture of plant seeds (Trifolium alexandrinum, Fagopyrum esculentum Moench, Trifolium incarnatum, Phacelia tanacetifolia, Sinapis alba, Trifolium repens), while experimental plots 1 and 4 were left without seeded vegetation. Moreover, a zeolite and an Ascophyllum nodosum-based biostimulant were added to experimental plots 3 and 4. The objectives were to select the most beneficial plant species for the plant-based bioremediation process, to evaluate applicability of different soil amendments for an enhanced hydrocarbon biodegradation, and to study their effects on the microbial community in soil. Our results showed an overall reduction in hydrocarbon pollution by more than 95% within 280 days. The rates of hydrocarbon degradation and changes in the microbial population were not affected by the presence of the zeolite and the biostimulant. In addition, the use of different plant species did not have a statistically significant effect on hydrocarbon degradation but affected microbial population dynamics, confirming stabile and diverse indigenous hydrocarbon-degrading microbial community in the native soil.

Ex situ bioremediation of diesel fuel-contaminated soil in two different climates

The petroleum industry is often faced with accidental spills and discharges that pollute valuable natural resources such as soil. The purpose of this study was to assess bioremediation potential of an on-site landfarming unit (LU), a highly economical solution that complies with the zero-waste policy, for bioremediation of the contaminated soil after an actual diesel fuel leakage in a fuel depot. The first aim was to evaluate the effects of different climates on hydrocarbon bioremediation. For this reason, a part of the contaminated soil was moved from the initial location with a sub-Mediterranean climate to an LU at another location with a temperate continental climate. Our results demonstrated that remediation in sub-Mediterranean climate is less effective than the remediation in a temperate continental climate. The second aim of this study was to evaluate the effect of different plant species on the microbial population during bioremediation. For that purpose, 365-day monitoring of phospholipid fatty acids (PLFA) was performed. Our results support the hypothesis that plant-assisted bioremediation can diminish toxic effects of diesel-polluted soil and that the changes in plant species during bioremediation cause changes in the microbial population.

The Effect of Petroleum-Derived Substances and Their Bioremediation on Soil Enzymatic Activity and Soil Invertebrates

Petroleum-derived substances (PDSs) as main pollutants of the natural environment can negatively affect the microbiological, biochemical, and biological properties of agricultural soils and, consequently, plant production. The present study aimed to determine the after-effect of PDSs such as petrol, used engine oil, and diesel fuel on the activity of selected soil enzymes (phosphatase, dehydrogenase, and urease) and on the occurrence of soil invertebrates. Moreover, changes in the analyzed parameters in response to bioremediation of the polluted soil by using ZB-01 preparation were investigated. The field experiments were performed four- and five-years post contamination. The results showed that even after five years, PDSs significantly modified the activity of soil enzymes; however, this effect was often varied, depending on the pollutant, enzyme, and time after soil contamination. Dehydrogenase seems to be a good indicator of soil contamination with PDSs, particularly diesel fuel. Engine oil and diesel fuel limited still the occurrence of soil invertebrates, particularly Collembola from the families Hypogastruidae, Isotomidae, and Entomobryidae, even after four and five years of contamination. This finding suggests the usefulness of these organisms in assessing soil pollution and in monitoring the progress of bioremediation. The effect of ZB-01 biopreparation on the activity of selected enzymes was varied. Its effect on the occurrence of soil invertebrates was usually beneficial, which was evident in diesel fuel-contaminated soil.

Assessing the Effect of Diesel Fuel on the Seed Viability and Germination of Medicago sativa Using the Event-Time Model.

The remediation of contaminated sites using plant-based techniques has gained increasing attention in recent decades. However, information on the effects of contaminant imbibition on seed viability and germination rates are often lacking in the literature. To this end, our research investigated, by means of an event-time model, the effect of diesel fuel imbibition on the seed viability and germination rate of Medicago sativa, a plant species with great potential for remediation of organic contaminants. The event-time model provided an accurate and biologically relevant method for analysing germination data. Our results reveal that the direct imbibition of diesel fuel by M. sativa seeds for ≤48 h, or their exposure to soil diesel fuel concentrations of 0–10 g/kg diesel fuel, affects their germination rates, as shown by increasing t50 values from 90.6 (±2.78) to 114.2 (±2.67) hours, without significantly affecting seed viability. On the other hand, diesel fuel imbibition of longer duration, or the exposure of M. sativa seeds to ≥20 g/kg diesel fuel-contaminated soils, leads to no further effect on time to seed emergence. Instead, these conditions compromise seed viability, resulting in a decrease in the proportion of germinated seeds from 0.91 (±0.03) in 10 g/kg diesel fuel contaminated soil to 0.84 (±0.04) and 0.70 (±0.05) in 20 and 30 g/kg diesel fuel-contaminated soils, respectively. The fact that low concentrations of diesel fuel and 0–48 h of direct imbibition delayed seed emergence without adversely affecting the percentage of viable seeds suggests that this inhibitory effect on germination at low diesel fuel exposure could be attributed more to physical constraints rather than biological damage on the seeds. The models used in this study provide an accurate and biologically relevant method for the analyses of germination data. This is vital since expensive germination experiments, be it in the field of toxicology or agriculture, deserve to be accurately analysed.

Construction and Evaluation of a Korean Native Microbial Consortium for the Bioremediation of Diesel Fuel-Contaminated Soil in Korea.

A native microbial consortium for the bioremediation of soil contaminated with diesel fuel in Korea was constructed and its biodegradation ability was assessed. Microbial strains isolated from Korean terrestrial environments, with the potential to biodegrade aliphatic hydrocarbons, PAHs, and resins, were investigated and among them, eventually seven microbial strains, Acinetobacter oleivorans DR1, Corynebacterium sp. KSS-2, Pseudomonas sp. AS1, Pseudomonas sp. Neph5, Rhodococcus sp. KOS-1, Micrococcus sp. KSS-8, and Yarrowia sp. KSS-1 were selected for the construction of a microbial consortium based on their biodegradation ability, hydrophobicity, and emulsifying activity. Laboratory- and bulk-scale biodegradation tests showed that in diesel fuel-contaminated soil supplemented with nutrients (nitrogen and phosphorus), the microbial consortium clearly improved the biodegradation of total petroleum hydrocarbons, and all microbial strains constituting the microbial consortium, except for Yarrowia survived and grew well, which suggests that the microbial consortium can be used for the bioremediation of diesel fuel-contaminated soil in Korea.

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.

Bioavailability and Bioremediation of Diesel Fuel-Contaminated Soil Using Organic Wastes as Supplement

Soil and surface water contamination by organic compounds is a common occurrence in most developing countries. This caused harmful effects on the environment and human beings. Bioremediation can be an alternative green technology for remediation of such hydrocarbon-contaminated soil. Bioremediation of soil contaminated with 5% and 10% (w/w) diesel fuel amended with 10% soy cake (SC), potato skin (PS) and tea leaf (TL) was studied for a period of 84 days, under laboratory condition. At the end of 84 days, the highest percentage of oil biodegradation (88%) was recorded in soil contaminated with 5% diesel fuel and amended with SC, while only 75% of oil biodegradation was recorded in soil contaminated with 10% diesel fuel and amended with SC. Bioavailability which was assessed by the hydroxypropyl cyclodextrin (HPCD) extraction method showed that bioavailability reduced in soil amended with organic wastes. Results of first order kinetic model to determine the rate of biodegradation of diesel fuel revealed that soil amended with SC recorded the highest kinetic rate of oil biodegradation 0.148 day and 0.103 day in 5% and 10% oil pollution. The results of this study demonstrated the potential of SC as a good substrate to enhance remediation of hydrocarbon contaminated soil at low pollution concentration.

Organic wastes to enhance phyto-treatment of diesel-contaminated soil

Toxic inorganic and organic chemicals are major contributors to environmental contamination and pose major health risks to human population. In this work, Dracaena reflexa and Podocarpus polystachyus were investigated for their potential to remove hydrocarbons from 2.5% and 1% diesel fuel-contaminated soil amended individually with 5% organic wastes (tea leaf, soy cake and potato skin) for a period of 270 days. Loss of 90% and 99% oil was recorded in soil contaminated with 2.5% and 1% oil with soy cake amendment, respectively, compared with 52% and 62% in unamended soil with D. reflexa at the end of 270 days. Similarly, 84% and 91% oil loss was recorded for P. polystachyus amended with organic wastes in 2.5% and 1% oil, respectively. Diesel fuel disappeared more rapidly in the soil amendment with SC than in other organic waste supplementation. It was evident that plants did not accumulate hydrocarbon from the soil, while the number of hydrocarbon-utilizing bacteria was high in the rhizosphere, thus suggesting that the mechanism of the oil degradation was rhizodegradation. The kinetic model result indicated a high rate of degradation in soil amendment with SC at 1% with D. reflexa compared with other treatments. Thus, a positive relationship was observed between diesel hydrocarbon degradation with plant biomass production. Dracaena reflexa with organic wastes amendment has a greater potential of restoring hydrocarbon-contaminated soil compared to P. polystachyus plant.

Small-scale studies towards a rational use of bioaugmentation in an Antarctic hydrocarbon-contaminated soil

AbstractBioaugmentation is a controversial strategy. In this work, the effect of the inoculum size and the absence of natural microflora on the efficiency of hydrocarbon removal were studied. Two levels of inoculum (106and 109CFU g-1) were applied to soil microcosms containing sterile (S6 and S9) and non-sterile (NS6 and NS9) oil contaminated Antarctic soil. Community controls (CC) and biostimulated autochthonous microflora (BAM) were also included. Total heterotrophic aerobic (THAB) and hydrocarbon degrading (HDB) bacteria as well as total petroleum hydrocarbons (TPH) were analysed. At day 0, THAB and HDB counts (CFU g-1) showed no differences among CC, BAM and NS6 but significantly higher values were observed in NS9 and S9. At day 60, three different levels of HDB were observed. The lower level was represented by CC (106CFU g-1), a second group (5 x 107CFU g-1) was represented by BAM, NS6, NS9 and S6, and the third level was constituted by S9 (1 x 109CFU g-1). TPH values at day 60 decreased significantly in all systems excluding the controls. NS6, NS9, S6 and S9 were not different from those corresponding to BAM. Results suggest that the bioaugmentation of a chronically diesel fuel-contaminated Antarctic soil is unlikely to be profitable or beneficial.

Field Detector Evaluation of Organic Clay Soils Contaminated with Diesel Fuel

Due to numerous types of uncontrolled petroleum releases into the environment such as leaking storage tanks, spills, and improper disposal of petroleum wastes, there is a need for quicker, more efficient methods to determine the levels of soil contamination for site remediation. The portable field detectors used most often in preliminary site evaluations are the flame ionization detector (FID) and the photoionization detector (PID). This research explored the relationship between these two instruments in analysis of two clay soil sites contaminated with diesel fuel. As in previous research, a log-log linear correlation was found between the PID and FID instruments for diesel fuel-contaminated soil at each site (R 2 > 0.91). Also, the correlation factors (0.64 and 0.60) between the field instruments at each site were found to be similar. It was asserted that either field instrument can be used to delineate the diesel fuel contamination at that site based upon a previously calculated correlation between the two instruments, and an overall numerical correlation between the field instruments can be used at various sites of similar soil and contamination characteristics. The implementation of the relationships between these two instruments could facilitate and accelerate site characterization in the future.

Correlations between PID and FID Field Analytical Instruments in the Analysis of Soil Contaminated with Diesel Fuel

Research was conducted to determine if there is a correlation between the data gathered by field analytical instruments in analyzing soil contaminated with diesel fuel. One instrument was equipped with a flame ionization detector (FID) and the other a photoionization detector (PID). The results showed that the concentration readings of the PID and FID displayed a linear relationship for soil recently contaminated with diesel fuel. However, for soil containing weathered diesel fuel in the field, a logarithmic relationship between the PID and FID readings was displayed. It was also determined by laboratory experimentation that the PID and FID readings both exhibited log-linear decreases over time for uncovered diesel fuel-contaminated soil. It was concluded that the PID and FID can both individually be used to evaluate soil contaminated by diesel fuel and might be interchangeable depending on the needs of the researcher.

Volatile Hydrocarbon Emissions from a Diesel Fuel-Contaminated Soil Bioremediation Facility

Concerns have been expressed that emissions of volatile hydrocarbons (HCs) from bioremediation facilities containing soils contaminated with petroleum HCs may negatively impact regional air quality or human health. Little information is available regarding the emission of HCs from bioremediation sites, and few field studies have been performed during which the flux of HCs has been directly measured during bioremediation. To aid in answering questions about the impact of bioremediation facilities on the atmospheric environment, a two-part field study was conducted over summer 1996 at a remote landfarm in northern Ontario where diesel fuel-contaminated soil was undergoing bioremediation. Volatile total hydrocarbon (THC) atmospheric flux measurements were successfully taken over 18 days using a flux gradient micrometeorological technique incorporating a THC detector constructed in-house. Peak THC emissions reached 131 μg C/m2/sec shortly after implementation and tilling of the landfarm soil. The influence of soil temperature and tillage on THC emissions was examined. Off-site inhalation exposure was considered with the aid of an ar-eal source model and results from speciated air samples collected on sorbent tubes and analyzed via gas chroma-tography/mass spectrometry (GCMS) techniques.

A micrometeorological technique to monitor total hydrocarbon emissions from landfarms to the atmosphere.

Landfarming is used to treat petroleum hydrocarbon-contaminated soils and a variety of waste streams from industrial operations. Wastes are applied to a soil surface and indigenous soil microorganisms utilize the hydrocarbons in the applied waste as a carbon source for metabolism, thereby biodegrading the applied material. Concerns have been expressed that abiotic losses, such as volatilization, play a significant role in hydrocarbon reduction within the soil. To assist in better defining atmospheric releases of total hydrocarbons from landfarms treating petroleum hydrocarbons, a flux gradient micrometeorological approach was developed and integrated with a custom-built total hydrocarbon detector, and a novel air sampling system and averaging algorithm. The micrometeorological technique offers unobtrusive spatially averaged real-time continuous measurements, thereby providing a time history of emissions. This provides opportunities to investigate mechanisms controlling emissions and to evaluate landfarm management strategies. The versatility of the technique is illustrated through measurements performed at a remote landfarm used to treat diesel fuel-contaminated soil in northern Ontario and during routine operations at two active refinery landfarms in southwestern Ontario.

A comparison of CSTR and SBR bioslurry reactor performance

A continuous-flow stirred tank reactor (CSTR) and a soil slurry-sequencing batch reactor (SS-SBR) were maintained in 8 l vessels for 180 days to treat a diesel fuel-contaminated soil. The SS-SBR provided markedly enhanced contaminant degradation relative to the CSTR. Diesel fuel removal efficiency was 96% in the SS-SBR, compared with 75% in the CSTR. Microbial growth was approximately 25% greater in the SS-SBR than the CSTR. However, significant biosurfactant production and foaming occurred in the SS-SBR, whereas none was observed in the CSTR. Surfactants were produced in the SS-SBR at concentrations up to 70 times the critical micelle concentration (CMC), but were biodegraded by the end of the cycle. Reactor operation was reversed after 80 days. The reactor converted from an SS-SBR to a CSTR lost surfactant production and showed reduced diesel fuel degradation. Converting the CSTR to an SS-SBR resulted in surfactant production and enhanced diesel fuel degradation. These results indicate that fill-and-draw operation selected for microbes with a greater ability to produce surfactants and degrade diesel fuel than the CSTR operation. Decreasing the diesel fuel addition rate in the SS-SBR by four times on day 160 reduced the maximum surfactant concentration and foam thickness by more than three times without affecting diesel fuel removal.