The aim of this article is to present the problem of purification of 50-year-old weathered wastes (soil) from waste pits—the result of oil drilling. The soil was deeply contaminated with petroleum hydrocarbons—total petroleum hydrocarbon (TPH) level: 85,654–101,842 mg kg dry mass. This work presents results of waste pit material purification with the use of stage technology: initial reclamation, basic bioremediation, and bioaugmentation (inoculation with indigenous microorganisms). The whole process was controlled with the use of gas chromatography/flame ionization detector. This analytical method enables observation of alternation in n-alkanes content during the consecutive stages of purification. According to this method, estimation of oil hydrocarbon biodegradation degree with the use of n-C17/Pr and n-C18/F indicators can be done. The use of biomarker C30-17α(H)21β(H)-hopane to normalize the TPH concentration in laboratory research enabled the creation of the first-order mathematical model of biodegradation. It is possible to recognize the dynamics of the following purification stages due to the calculated first-order biodegradation constants. Decrease in the TPH content (63.8–65.1%) was a result of laboratory tests led in 130 days of basic bioremediation. The next stage of soil purification (130 days) included inoculation with biopreparation based on indigenous microorganisms—TPH decrease in 80.7–81.7%. Laboratory tests results enabled elaboration of purification methods applied in tested waste pits in industrial conditions (in situ). The technology of the G-44 and G-12 waste pits purification from huge petroleum hydrocarbons content, consisting of stage purification process, enables the TPH decrease to the satisfactory level in 3 years. 相似文献
In order to improve and support decision-making for the selection of remedial techniques for contaminated sites, a multi-criteria assessment (MCA) method has been developed. The MCA framework is structured in a decision process actively involving stakeholders, and compares the sustainability of remediation alternatives by integrating environmental, societal, and economic criteria in the assessment.
Materials and methods
The MCA includes five main decision criteria: remedial effect, remediation cost, remediation time, environmental impacts, and societal impacts. The main criteria are divided into a number of sub-criteria. The environmental impacts consider secondary impacts to the environment caused by remedial activities and are assessed by life-cycle assessment (LCA). The societal impacts mainly consider local impacts and are assessed in a more qualitative manner on a scale from 1 to 5. The performance on each main criterion is normalized to a score between 0 and 1, with 1 being the worst score. An overall score is obtained by calculating a weighted sum with criteria weights determined by stakeholders. The MCA method was applied to assess remediation alternatives for the Groyne 42 site, one of the largest contaminated sites in Denmark.
Results and discussion
The compared remediation alternatives for the site were: (1) excavation of the site followed by soil treatment; (2) in situ alkaline hydrolysis; (3) in situ thermal remediation; and (4) continued encapsulation of the site by sheet piling. Criteria weights were derived by a stakeholder panel. The stakeholders gave the highest weighting to the remedial effect of the methods and to the societal impacts. For the Groyne 42 case study, the excavation option obtained the lowest overall score in the MCA, and was therefore found to be the most sustainable option. This was especially due to the fact that this option obtained a high score in the main categories Effect and Social impacts, which were weighted highest by the stakeholders.
Conclusions
The developed MCA method is structured with five main criteria. Effect and time are included in addition to the three pillars of sustainability (environment, society, and economy). The remedial effect of remediation is therefore assessed and weighted separately from the main criteria environment. This structure makes interpretation of criteria scores more transparent and emphasizes the importance of effect and time as decision parameters. This also facilitated an easier weighting procedure for the stakeholders in the case study, who expressed a wish to weigh the remedial effect independently from the secondary environmental impacts.
This work examines the rates of bioremediation during a landfarming process. A field study was performed using three types of soil, which were contaminated with two different hydrocarbon concentrations: 20,000 and 50,000 ppm of total petroleum hydrocarbons (TPH). They were subjected to landfarming under the action of different treatments, based on the provision of irrigation, aeration by rototilling, fertilizer, and surfactant. The biodegradation of TPH, considering concentration and families of hydrocarbon compounds (including polycyclic aromatic hydrocarbons, PAHs), was precisely measured for a period of 486 days. The results show how biodegradation rates depend on soil texture, initial contamination level, and type of amendment. Thus, the combination of fertilizer, irrigation, and aeration was the best treatment for treating the soil contaminated with 20,000 ppm of TPH (TPH final concentrations were reduced to a range of 49 to 62% depending on the soil texture). In the case of parcels contaminated with 50,000 ppm of TPH, the most effective treatment combined the supply of fertilizer, surfactant, irrigation, and aeration (TPH final concentrations were reduced to a range of 47 to 63%, depending on the soil texture). The best biodegradation results are obtained for soils with coarser textures and using the treatment with fertilizer, irrigation, and aeration. In addition, the application of surfactant did not imply a significant improvement in the level of biodegradation of hydrocarbons in soil contaminated with 20,000 ppm of TPH, whereas in soils contaminated with 50,000 ppm of TPH, it played a leading role.
Background, Aims and Scope An out-of-service oil distribution and storage station (ODSS), which operated from 1966 to 2000 in Mexico, is contaminated
mainly by gasoline and diesel, showing the presence of methyl-tert-butyl-ether, benzene, toluene, ethyl benzene, and xylenes.
Nine of the 16 polycyclic aromatic hydrocarbons were found, as well as Fe, Pb, V, and Zn. The health risk assessment suggested
the necessity of reducing of three PAHs [benzo(a)anthracene, benzo(a)pyrene, and benzo-(b)fluoranthene], and vanadium. The
aim of this work is to show that soil washing (on-site) and biopiles are excellent remediation methodologies to treat soils
contaminated with petroleum derivates and metals. Applying them, it is possible to reach the goal value of 2,000 mg TPH/kg
in a few months, as requested by Mexican legislation.
Methods More than 140 m3 were excavated from the ODSS. Three soil-washing dishes were built. 1540 m3 were treated by soil washing using a nonionic surfactant. A 100 m3 biopile was built to study the system capabilities in the biodegradation of around 4,500 mg/kg of TPH using the autochthonous
microflora.
Results and Discussion The soil washing, average TPH-removal value was 83%, but values up to ca. 93% were observed. Removal values resulted in a
function of the TPH initial values. Biopile (100 m3) worked during 66 days, reaching a TPH-removal value of 85%. At the end of the processes, no PAHs were detected. The contaminated
soil was treated successfully, reaching the legislation limits (TPH values under 2,000 mg/kg, and a significant reduction
in PAH concentrations).
Conclusion and Recommendation Both systems are suitable for remediation purposes, achieving high removal efficiencies at short and medium stages. It is
highly recommended to proceed with soil washing studies, identifying new products, and mixtures, which could reduce costs
and assure optimum operation. 相似文献
In this biological oxygen demand (BOD) study, the manometric respirometric BOD OxiTop® method was used to monitor the biodegradation of two summer grade (SFO 1 and 2) and two winter grade light fuel oils (WFO 1 and 2) in OECD 301 F conditions, in groundwater, and in two different Finnish forest soils (mineral-poor and mineral-rich). The biodegradation measurements in the OECD 301 F conditions were carried out in two nutrient solutions for 28 days. In both solutions WFO 1 reached the highest biodegradation degree, 32% in the solution OECD 301 F, and 70% in a solution containing additional ammonium chloride. In groundwater conditions all the biodegradation degrees of fuel oils remained below 2% within the 28-day period. SFO 1 reached the highest 30 day biodegradability (4%) in mineral-poor soil, 18% in mineral-rich soil. In a 189-day measurement in a mineral-rich soil, the biodegradation degree for the SFO 1 was 94%. The manometric respirometric method proved to be a very suitable and practicable measurement method for the purpose of biodegradation studies of highly volatile light fuel oils, because in this method samples are treated to a lesser degree than in conventional methods, and dilutions are not needed. Results also indicated a considerable effect of conditions on the biodegradability in both water and soil environments. The results of these biodegradation studies could be used when planning in situ treatment methods based on natural biodegradation. In situ treatment methods are eco-efficient, and are especially suitable for sparsely populated sites. 相似文献
A greenhouse pot experiment was conducted for investigating the capability of a grass (annual ryegrass), a legume (summer vetch), and a crucifer (white mustard) to grow in a soil with portions from a former coal gasification site, influence the soil bacterial community, and promote the biodegradation of petrol hydrocarbons (PHCs). Soil concentrations of 1517 mg kg−1 of total petrol hydrocarbons (TPHs), including 71.4 mg kg−1 of total US EPA priority polycyclic aromatic hydrocarbons (TPAHs) have caused a significant (P < 0.05) reduction in shoot and root dry matter yields by more than 50%. Culturable bacteria and actinomycetes in soil were as much as 18-fold more abundant and the species composition was largely altered because of PHC contaminants and depending on crop species and age. After 95 days, 68.7% of initial TPH amounts and 59% of the TPAHs had disappeared from unplanted soil. Mustard and vetch fostered the removal of PHCs from soil reaching final TPH concentrations that were 15.6% and 12% lower than in unplanted soil. Both crops elicited the greatest degradative root activities and sustained particularly great populations of rhizosphere bacteria that are known hydrocarbon degraders. None of the crops aided the reduction of TPAHs in soil. 相似文献
Phytoremediation is a novel treatment option for weathered, hydrocarbon contaminated, flare-pit soil in prairie ecosystems. The remediation potential of six different naturalized prairie plants was assessed by examining their impact on the degradation potential of indigenous bacterial communities. Culture-based and culture-independent microbiological methods were used to determine if mixed plant treatments stimulate different microbial communities and catabolic genotypes in comparison to individual plant species that comprise the mix. DGGE analysis of PCR-amplified 16S rRNA genes revealed that alfalfa (Medicago sativa) had a dominant effect on the structure of rhizosphere microbial communities in mixed plant treatments, stimulating relative increases in specific Bacteroidetes and Proteobacteria populations. Alfalfa and mixes containing alfalfa, while supporting 100 times more culturable PAH degraders than other treatments, exhibited only 10% TPH reduction, less than all planted treatments except perennial rye grass (Lolium perenne). Total petroleum hydrocarbon (TPH) reduction was greatest in single-species grass treatments, with creeping red fescue (Festuca rubra) reducing the TPH concentration by 50% after 4.5 months. Overall TPH reduction throughout the study was positively correlated (p<0.001) to culturable n-hexadecane degraders. 相似文献
The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study. 相似文献
The effects of two different biological treatments on hydrocarbon degradation and on soil biological activities were determined during a 100-d incubation period. An evaluation of soil biological activities as a monitoring instrument for the decontamination process of diesel-oil contaminated soil was made using measurements of organic carbon content, soil microbial respiration, soil ATP and dehydrogenase, β-glucosidase, lipase enzyme activities. Five samples were used: S (control, uncontaminated soil), CS (contaminated soil), SCS (sterilized contaminated soil), CFS (contaminated soil plus N and P), CCS (contaminated soil plus compost). The relationships between soil parameters and the levels of total petroleum hydrocarbons (TPH) residues were investigated. Results showed that inorganic nutrients NP and compost stimulated hydrocarbon biodegradation but not all biological activities to a significant extent. The residual hydrocarbon trend was positively related with that of the organic C content, microbial respiration and with β-glucosydase activity, while both soil lipase and dehydrogenase activities were negatively related with the hydrocarbon trend. Lipase activity was found to be the most useful parameter for testing hydrocarbon degradation in soil. 相似文献
Journal of Soils and Sediments - The remediation of diesel-contaminated hydrophobic soil is difficult due to the inability of aqueous phase remedial agents to infiltrate the soil. This novel... 相似文献
Research on oil residuals in lowland forest soil was carried out in 6 sample plots in the lowland forest ecosystem located in an oil field. Four plots were differently affected in terms of discharged oil and the time lapsed after the accident, as well as in terms of micro-relief terrain features. One plot was established in a reclaimed mud ditch site, while the control plot was set up in a micro-relief elevation outside the influence of oil pollution. Total petroleum hydrocarbon (TPH) concentrations were measured at three soil depths at the beginning and the end of the vegetation period. The analysis of the results revealed significant differences in petroleum hydrocarbon concentrations among the sites. Increased TPH concentrations were recorded in several plots, while the values measured in some other plots indicated very low quantities of residual TPH in the soil. The highest average TPH concentrations (200–400 mg kg1) were recorded in the mud ditch site. In one of the plots exposed to oil pollution after an oil pipe rupture, there was the constant presence of increased TPH concentration in the surface soil part (≥200 mg kg1 on average). The sporadic presence of increased TPH concentrations in micro-depressions that cannot be attributed to a local accident indicates seasonal soil pollution with petroleum carbohydrates from floodwater. The soil in the sample plots is not contaminated with soluble salts or heavy metals. Low values of TPH concentrations in the soil water eluate indicate that the soil does not represent a source of hydrospheric pollution with petrol hydrocarbons. 相似文献
Soil erosion and land degradation are global problems and pose major issues in many countries.Both soil erosion and mass movement are two forms of land degradation and humans play important roles in these geomorphological processes.This paper reviews slope processes associated with mass movement and soil erosion and contributory factors,including physical and human agents.Acting together,these cause diverse geomorphological features.Slope processes are illustrated by reference to case studies from Brazil and UK.The causes and impacts of erosion are discussed,along with appropriate remedial bioengineering methods and the potential of the measures to prevent these types of environmental degradation.Although there are several agents of erosion,water is the most important one.Cultivation can promote soil erosion,due to ploughing and harvesting,which moves soil down slopes.Soil erosion and mass movement data would inform the viability of soil conservation practices.Integrated management of drainage basins offers a promising way forward for effective soil conservation and soil remedial bioengineering in Brazil and UK. 相似文献
In order to provide highly effective yet relatively inexpensive strategies for the remediation of recalcitrant organic contaminants,
research has focused on in situ treatment technologies. Recent investigation has shown that coupling two common treatments—in
situ chemical oxidation (ISCO) and in situ bioremediation—is not only feasible but in many cases provides more efficient and
extensive cleanup of contaminated subsurfaces. However, the combination of aggressive chemical oxidants with delicate microbial
activity requires a thorough understanding of the impact of each step on soil geochemistry, biota, and contaminant dynamics.
In an attempt to optimize coupled chemical and biological remediation, investigations have focused on elucidating parameters
that are necessary to successful treatment. In the case of ISCO, the impacts of chemical oxidant type and quantity on bacterial
populations and contaminant biodegradability have been considered. Similarly, biostimulation, that is, the adjustment of redox
conditions and amendment with electron donors, acceptors, and nutrients, and bioaugmentation have been used to expedite the
regeneration of biodegradation following oxidation. The purpose of this review is to integrate recent results on coupled ISCO
and bioremediation with the goal of identifying parameters necessary to an optimized biphasic treatment and areas that require
additional focus. 相似文献
To devise effective procedures for the remediation of soil contaminated by VOCs, an improved understanding of their fate and transport mechanisms in soil is essential. To show the effect of plants on the dissipation of 1,1,1-trichloroethane (TCA), trichloroethylene (TCE) and tetrachloroethylene (PCE), two types of experiments, vial and column, were conducted. The results suggested that keeping the soil moisture content at field capacity is desirable for VOCs dissipation. All VOCs were dissipated quickly in unplanted columns than planted conditions in early periods of the experiment because more volatilization occurred in unplanted conditions. The plants could take up and retard volatile contaminants, and prevent contamination of ambient air. Although the time for acclimation for microbial communities to contaminants for enhanced biodegradation should be considered, phytoremediation is potentially a cost-effective remediation technique for soils contaminated by volatile organic compounds (VOCs). 相似文献
