Spectroscopic determination of poly-aromatic compounds in petroleum contaminated soils

The determination of poly-aromatic hydrocarbons (PAHs) in the soil is of interest because of their carcinogenic and mutagenic activity in biological systems. The present study deals with the rapid application of infrared, fluorescence, synchronous luminescence spectrometries and gas chromatography to detect organic pollutants and their quantity in the soil. Sohxlet extraction followed by column separation was used to isolate organic pollutants. Although several solvent mixtures were used as eluents for the column, the solvent mixture, hexane:dichloromethane (50:50) efficiently extracts the aromatic compounds. Total petroleum hydrocarbons (TPH) measured by IR were found at high concentrations (30810.0 ppm) in the contaminated soil compared with the reference soil (30.0 ppm). Furthermore, the fluorescence results reveal that almost one-fourth of the 30810.0 ppm are aromatic hydrocarbons. In addition, the presence of PAHs such as naphthalene, acenaphthene, fluorene, fluoranthene, phenanthrene, pyrene, benzo(a)pyrene, chrysene, and dibenzo(a,h)anthracene in the polluted soil was determined by using synchronous study.     

Iron compounds and oil biodegradation in overmoistened contaminated soils: A review of publications

In Russia, the areas of oil pollution gradually shift toward the north into the zone of increased moistening with widespread hydromorphic soils. In this zone, the role of the rapid aerobic degradation of hydrocarbons decreases, while that of slow anaerobic degradation increases. The biological reduction of Fe(III) only proceeds at the expense of the energy of oxidation of organic substances, including oil hydrocarbons, in the oil-polluted soils. This favors the development of technogenic gleying. In contrast to the uncontaminated background soils, in which gleying is correctly considered a degradation process, the same process in the oil-contaminated mineral soils plays a positive role, because it is accompanied by the oxidation of organic pollutants, which otherwise penetrate into rivers and lakes with water flows. The role of Fe(III) reduction may be significant: at one of the oil-spill sites, one-third of the organic pollutants degraded within twelve years after an accident in the anaerobic zone due to Fe(III) reduction. Both iron hydroxides and clay minerals enriched in Fe(III) participate in the reduction processes. In the anaerobic zone, the destruction of organic pollutants begins several years after the relevant natural microorganisms become active. The reduction of Fe(III) reaches its maximum faster than the process of methanogenesis. Upon the soil’s cooling in the winter, the reduction of Fe(III) is replaced by the spontaneous formation of iron oxides (oxidogenesis). Thus, alternating reduction ↔ oxidation reactions proceed in the soils with a contrasting temperature regime. Iron oxides formed in the winter are reduced to Fe(II) in the summer and, thus, resume the associated oxidation of organic pollutants upon the stagnant moisture regime. Therefore, upon monitoring of hydromorphic oilcontaminated soils, special attention should be paid to the forms of iron compounds.     

Adjusted Fick's law for gas diffusion in soils contaminated with petroleum hydrocarbons

In bioremediation, hydrocarbon biodegradation rates can be estimated from measured O₂ and CO₂ profiles in situ. Although Fick's law is typically used in calculating the respiration rates, its theoretical base is weak. We propose an adjusted Fick's law with a correction term for the advective flux. We evaluated the applicability of this model to simulate gas diffusion associated with passive degradation of petroleum hydrocarbons in a biopile by comparing the results of this model with the results of Fick's law and the Stefan–Maxwell equations. The deviations from the use of Fick's law depended strongly on the consumption rate of oxygen, the respiration quotient, the mineralization quotient and the volatility of the hydrocarbon. In the whole range of calculated CO₂ concentration versus depth profiles, production rates of CO₂ could be estimated by Fick's law with a maximum deviation of 6%. For the consumption rate of O₂ the maximum deviation is 19%. However, when we used the adjusted Fick's law, the deviations from the results obtained with the Stefan–Maxwell equations were much smaller. The deviations amounted up to only 4%, when the respiration rate r was 1.5 or a hydrocarbon with volatility similar to benzene was present. If the presence of a hydrocarbon was neglected in the calculations, the deviations of the adjusted Fick's law from the results obtained with the Stefan–Maxwell equations were substantial for a hydrocarbon with volatility similar to benzene or toluene.     

采用通气堆沤对石油烃污染土壤进行生物修复

Laboratory simulation studies and a composting pilot study were conducted to evaluate the capacity of three strains of fungi, indigenous fungus Fusarium sp. and Phanerochaete chrysosporium and Coriolus Versicolor, to remediate petroleum-contaminated soils. In laboratory, the fungi were inoculated into a liquidculture medium and the petroleum-contaminated soil samples for incubation of 40 and 50 days 5 respectively. In the 200-day pilot study, nutrient contents and moisture were adjusted and maintained under aerobiccondition in composting units using concrete container (118.5 cm × 65.5 cm × 12.5 cm) designed specially for this study. The laboratory simulation results showed that all the three fungi were effective in degrading petroleum in the liquid culture medium and in the soil. At the end of both the laboratory incubations, the degradation rates by Phanerochaete chrysosporium were the highest, reaching 66% after incubation in liquid culture for 50 days. This was further demonstrated in the composting pilot study where the degradation rate by P. chrysosporium reached 79% within 200 days, higher than those of the other two fungi (53.1% and 46.1%), indicating that P. chrysosporium was the best fungus for bioremediation of soil contaminated with petroleum. Further research is required to increase degradation rate.     

Polycyclic aromatic compounds and microtox® acute toxicity in contaminated sediments in Sweden

Limnic and brackish aquatic sediments from contaminated locations in Sweden were analysed for polycyclic aromatic compounds (PACs) and tested for acute aquatic toxicity. The organic compounds were analysed in solvent-extractable and alkaline-treated fractions to complete the analysis of a set of priority pollutants according to the Swedish EPA. Additionally, the acute toxicity was measured by the solid phase Microtox test. The measured effects were correlated with sedimentological and chemical parameters. Analysis revealed no indication of a contribution of PACs to the acute sediment toxicity in highly contaminated sediments, with concentrations in the range of 11.3-307 μg SPAC_37/39/g dry matter. Despite a high ranking of 3 to 5 within the Swedish EPA list for coastal sediments, the acute toxicity results indicate a very low bioavailability of the analysed PACs from the creosote and combustion-contaminated sediments. A correlation of acute toxicity to elemental sulfur was indicated.     

Bioremediation of the soil contaminated with petroleum oil products using sewage sludge

ABSTRACT

The remediation technologies of soils contaminated with petroleum products are developed in two main directions: the first one encompasses searching for new effective bioagents and the other one explores the ways to activate those microorganisms present in the soil that are capable of degrading oil. The objective of this research was to determine if it is possible to increase the effectiveness of biodegradation of petroleum products by using chemical additives. The soil was supplemented with additives: CuSO4, MnSO4, KMnO4, H2O2, 5% and 10% chemical industry plants sludge, 5% and 10% Stock Company ‘Klaipedos vanduo’ (SC‘KV’) municipal wastewater treatment plants sludge. The data suggest that all the additives statistically significantly stimulated the degradation of diesel fuel (F = 12.01; p = .001) and black oil (F = 9.93; p = .001) compared with the control. It was determined that diesel fuel was degraded the fastest in samples with KMnO4, where efficiency of degradation was 90%, and 88% efficency in samples with 10% chemical industry plants sludge. Black oil was degraded the best in samples, where KMnO4 was added: efficiency of degradation was up to 63%. In the samples with 10% of sewage sludge from chemical industry plant degradation efficiency was 62%.     

Influence of environmental factors on the biological treatment of organic compounds in contaminated lagoon sediments

Background and Scope  Many technologies available to remediate soils are not cost-effective when applied to marine and lagoon sediments, due to the physico-chemical characteristics of these matrices (high percentages of small particle size material, high moisture and organic matter content, many different types of inorganic and organic contamination). For these types of waste, slurry phase bioreactors can provide versatile processes, with very high removal efficiencies of recalcitrant organic compounds. The biodegradation of these contaminants strictly depends on the specific structure of the molecules and on environmental factors, such as the dissolved oxygen concentration, salinity, pH, and macronutrient availability. This paper presents the results of lab-scale tests performed to investigate the effect of the above-mentioned factors on the removal efficiency of saturated hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) in slurry phase biological treatment of lagoon sediments. Methods  Sediments were contaminated by saturated hydrocarbons (958 mg/kg d.w.), polyaromatic hydrocarbons (PAHs) (29 mg/kg d.w.) and polychlorobiphenyls (PCBs) (236 μg/kg d.w.). Carbon to nitrogen to phosphorous ratios in the matrix were not properly balanced for biological treatment. High concentrations of metals were also present (Cu: 200 mg/kg d.w.; Zn: 1710 mg/kg d.w.; As: 33 mg/kg d.w.; Cd: 13 mg/kg d.w.; Pb: 244 mg/kg d.w.). Biodegradation studies were carried out at 21 ± 1°C, in completely mixed slurry phase aerobic, anaerobic and sequential anaerobic/aerobic batch systems (3.5 1), with a solid to liquid ratio of 10% w/w. Where required, anaerobic conditions occurred naturally within three days of not aerated treatment. The aerated reactors were also equipped with traps for the waste vapors. Twelve tests were performed, over a period between ten and twenty-two days, mixing water, sediments and different amounts of various additives (macronutrients to balance C:N:P to 100:10:1 w/w, sodium chloride from 0 to 20 g/1, pH buffer solution) in the reactors, depending on the test being performed. Results and Discussion  No significant differences among the removal efficiencies of saturated hydrocarbons in tests could be observed. Abatements between 63% and 93% were obtained. The dissolved oxygen concentration was the most critical factor affecting the treatment of PAHs. Removal efficiencies below 20% were obtained for two and three-ring PAHs in the non-aerated tests. Higher values, between 45% and 61%, were obtained for these compounds in the aerated treatments; however, large (16% to 21%) abiotic losses (volatilization) were observed in these cases. Four-ring PAH removal efficiency was below 5% in all the non-aerated treatments, except for test performed without additions (30%); in the aerobic processes, removal efficiencies between 40% and 50% were obtained, except for test performed with nutrient addition and 10 g NaCl/1 (16%). Abatements of five and six-ring PAHs were between 43% and 69% in the aerated tests, and between 17% and 51% in the non-aerated treatments. Concerning PCBs, tests evidenced that reductive dehalogenation mechanisms have occurred in the anaerobic reactors with the most stable pH values, resulting in an increase of 2,4,4′-CB and 2,2′,5,5′-CB concentrations; the aerobic treatments did not modify the PCB mixture. In both types of systems, no variation of the total PCB concentration could be observed. Conclusions  This study showed that saturated hydrocarbon removal efficiency was nearly insensitive to the environmental factors investigated. The molecule structure and the dissolved oxygen concentration were the most affecting factors the removal efficiency of PAHs. PCB degradation under anaerobic conditions could be related to the pH values measured during the tests. Evaluation of results suggested that the abatement of pollutants investigated was not limited by a high salinity. High concentrations of dissolved metals and macronutrient addition did not influence the removal efficiency. Recommendations and Outlook. The slurry phase biological treatment of contaminated sediments could be applied whenever moderate removal efficiencies were required for remediation from saturated hydrocarbons and PAHs within a few days; further studies should be performed to improve the PCB abatement. Aerobic conditions should be maintained for the biodegradation of polyaromatic compounds; seawater or lagoon water could be used in the system.     

Immobilization of cadmium in simulated contaminated soils using thermal-activated serpentine

ABSTRACT

The thermal-activated serpentine prepared by heating natural serpentine at different temperatures was used to immobilize cadmium (Cd) in simulated contaminated soils. The results showed that the increasing soil pH induced by adding serpentine was primarily responsible for reducing the content of TCLP-Cd (toxicity characteristic leaching procedure-Cd) in soil. Furthermore, adding thermal-activated serpentine could promote the transformation from exchangeable form of Cd in soil to low bioavailable Cd (Fe-Mn oxides, carbonate, and residual form) by surface adsorption and surface precipitation, and then reduced the bioavailability of Cd in soil. Under the same treatment condition, adding S700 (serpentine activated at 700°C) exhibited better performance to immobilization of Cd, and it could reduce exchangeable Cd by 23.76~36.49%, and increase carbonate, Fe-Mn oxide, and residual form of Cd by 6.03~8.03%, 6.05~8.35%, and 11.17~19.58%, respectively. These results indicated that thermal-activated serpentine would be the great potential for immobilization of Cd in soil.     

Phytoremediation of soils contaminated by organic compounds: hype,hope and facts

Journal of Soils and Sediments - The present opinion paper is focused on the phytoremediation of organic pollutants and is based on the lectures given by the author during the International...     

Prediction of landfarming period using degradation kinetics of petroleum hydrocarbons: test with artificially contaminated and field-aged soils and commercially available bacterial cultures

Purpose

This study predicts the optimal landfarming period for the total petroleum hydrocarbons (TPHs)-contaminated field soils that are subject to the combined landfarming and Fenton oxidation treatment.

Materials and methods

The TPHs degradation in the artificially contaminated model soils and the field-aged contaminated soils were compared in a laboratory scale. The soils were bioaugmented with the 16 petroleum hydrocarbon-degrading microbial cultures that are commercially available in Korea.

Results and discussion

The TPHs degradation by bioaugmentation in the model soils was 81?±?2% after 56 days, while it was only 27?±?2% after 74 days in the field-aged soils. The lower degradation in the field-aged soils can be attributed to the removal of a large part of the biodegradable and volatile TPHs fractions during the weathering process. The two-compartment model that can depict a fast-degradation phase followed by a slow-degradation phase predicted that the remedial goal of 475 mg kg^?1 of TPHs could be achieved in the model soils within the conventional landfarming period of 60–120 days in Korea; however, the predicted period for the field-aged soils (710–4,086 days) was not practical requiring a combined biological and chemical treatment approach. Based on the kinetics study, the optimal landfarming period for the field-aged soils was 3 weeks and pre-Fenton oxidation can be used to meet the remedial goal.

Conclusions

The two-compartment model can be useful for predicting landfarming period for the combined landfarming and Fenton oxidation treatment of field-aged TPHs contaminated soils. The prediction of the optimal landfarming period could lead to the reduction in both the treatment cost and period.     

Arsenic, lead, and zinc compounds in contaminated soils according to EXAFS spectroscopic data: A review

The application of the synchrotron technique of the third generation in soil science has permitted researchers to perform a quantitative mineralogical microanalysis in undisturbed samples and to reveal the relationship between the microelements and the solid phase of soils. Three principal methods are used in this technique: microfluorescence (μXRF), microdiffraction (μXRD), and the expanded analysis of the fine structure of the adsorption spectra. By the data of EXAFS spectroscopy, secondary arsenic was found to occur in three forms in soils, i.e., As adsorbed on iron hydroxides, scorodite (FeAsO₄ · 2H₂O, and As⁵⁺ containing jarosite. Despite the high share of carboxyl groups in the organic substance of soils, lead is more readily chelated by the functional groups of aromatic rings to form bidentant complexes. Lead phosphates are the most stable form of Pb in soils. One of the phosphates, i.e., pyromorphite Pb₅(PO₄)₃Cl has been found in ore tailings, lawn soils, soils near some chemical plants, and in soils within geochemical anomalies. The secondary Zn compounds are represented by Zn-containing silicate (kerolith) Si₄Zn₃O₁₀(OH)₂ and, to a lesser extent, by zinc fixed by manganese oxides (birnessite) and iron hydroxides (feroxyhyte).     

基于AHP和TOPSIS的污染场地修复技术筛选方法研究

污染场地作为潜在的污染源,多位于城市人口密集区,具有较大环境风险,且随我国城市产业结构的调整有逐年增加的趋势,引起国家的日益重视。目前国内外应用于污染场地修复的技术类型较多,采用科学的方法选择技术适用、经济可行和环境友好的修复技术具有重要意义。在分析了已有的污染场地修复技术筛选方法和解决多参数决策问题的方法及工具的基础上,提出了基于层次分析法（AHP）和逼近理想解的排序法（TOPSIS）的污染场地修复技术筛选决策流程,构建了污染场地修复技术筛选的指标体系,通过领域专家调查和AHP法获得修复技术筛选不同指标的权重,然后采用TOPSIS法对污染场地修复技术进行排序。利用该方法筛选与某案例污染场地的实际筛选结果接近一致。AHP和TOPSIS结合运用于解决复杂的多因素决策问题,既能克服AHP在不易定量化指标上的主观性,又能避免TOPSIS对指标权重的忽视,能够为土地拥有者或环境工作者解决实际修复技术筛选问题提供了有益的工具。     

Group composition of heavy metal compounds in the soils contaminated by emissions from the Novocherkassk power station

The effect of natural and technogenic factors on the mobility and transformation of metal compounds was studied from an analysis of the fractional-group composition of Cu, Zn, and Pb compounds in the soils of areas adjacent to the Novocherkassk power station. Changes in the composition of Cu, Zn, and Pb compounds in the soils of technogenic landscapes were estimated. The effect of aerosol technogenic emissions on the mobility of metal compounds was revealed; a higher metal mobility was found in soils with low buffering capacity. Common and specific features of the formation of Cu, Zn, and Pb compounds in soils were determined. The role of individual soil components in the retention of metals in clean and contaminated soils was established.     

Biodegradation of hexachlorocyclohexane-isomers in contaminated soils

Several sites that are contaminated with isomers of the chlorinated insecticide hexachlorocyclohexane (HCH) are present across the globe and cause toxicity. For their bioremediation, we studied the degradation of HCH-isomers in contaminated soils by an isolate Pseudomonas aeruginosa ITRC-5. The degradation is optimal at 2 mg technical-HCH (t-HCH)/g soil, 15% water content, pH 8.0, temperature 28 °C and inoculum density 10⁶ colony forming unit/g soil. Under these conditions, from 5 kg soil, >98% α- and γ-HCH, 17% β-HCH and 76% δ-HCH are degraded after 15 days of incubation, which is accompanied with the release of 600 μg chloride/mg t-HCH. Concomitant to the degradation, a four-fold reduction in the toxicity of HCH-isomers to earthworm, Eisenia foetida, is also observed. Addition of ITRC-5 enhanced the degradation of soil-applied HCH-isomers in ‘open field’ conditions as well, and 97%, 43%, 94% and 77% of α-, β-, γ- and δ-HCH, respectively, are degraded after 12 weeks of incubation. Thus, the bacterium causes microbial degradation and detoxification of HCH-isomers, and can be used for the bioremediation of contaminated soils.     

香薷属植物在重金属修复中的应用进展

香薷属植物应用于重金属修复经历了矿区植物资源调查和比较、室内模拟研究、田间规模修复以及修复后处置研究,已经初步形成一个植物修复技术的完整体系。在现有技术条件下,把生态修复模式、品种驯化及诱导剂"配方"应用到香薷属植物修复土壤重金属污染对提高修复效率具有重要意义。     

Saturated hydrocarbons in the background and contaminated soils of the cisurals

A homologous series of n-alkanes (C₂₀–C₃₅) was identified in peaty-podzolic-gleyic soils. Structures with odd numbers of carbon atoms (C₂₅–C₃₅) were predominant in the soil organic matter. It was found that the major amount of both odd and even n-alkanes was accumulated in the peaty litter. In the mineral horizons, the mass fraction of the odd n-alkanes abruptly decreased to become comparable to that of the even n-alkanes in the soil-forming rock.     

Effect of wetting conditions on the fractional composition of heavy metal compounds in agrosoddy-podzolic soils contaminated with sewage sludge

Excessive wetting significantly affects the physicochemical, chemical, and biological properties of soils and changes the valence of Fe and Mn and the fractional composition of their compounds, as well as the compounds of the microelements and heavy metals bound to them. It was found that the metals are subdivided into three groups with respect to the soil wetting conditions: (1) the iron-group metals, the state of which is determined by the soil wetting conditions, the development of the reduction processes, and the status of the Fe and Mn compounds as the main sorption complexes closely bound to Co and Ni; (2) the Cu and Pb compounds, the status of which depends on the soil wetting and redox conditions and which are closely bound to organic matter and Fe and Mn compounds; and (3) the Zn and Cd compounds, the status of which little depends on the soil wetting and redox conditions and which are characterized by a low affinity for Fe, Mn, and organic compounds.     

Perchlorate biodegradation in contaminated soils and the deep unsaturated zone

In the United States, perchlorate has been officially recognized as an environmental contaminant. In Israel, widespread perchlorate contamination has been found in the 40-m deep vadose zone near an ammonium perchlorate manufacturing plant north of Tel Aviv, above the central part of Israel's coastal aquifer, with peak concentrations of 1200 mg kg_sediment^?1. In this study, we examined the perchlorate-reduction potential by native microbial communities along this deep contaminated vadose zone profile. We analyzed the effect of various concentrations of nitrate on perchlorate reduction and determined whether perchlorate concentrations in the profile are toxic to the native microbial population. All experiments were performed in soil slurries with sediments taken from the contaminated site. Perchlorate was reduced to chloride in three (1, 15 and 35 m) of the four examined sediment samples taken from different depths (1, 15, 20, and 35 m below surface). No activity was observed in the sediment sample from 20 m below land surface, suggesting low viable microbial communities and water content, and high perchlorate concentrations. In the presence of nitrate, the lag time for perchlorate degradation was inversely correlated to nitrate concentration. We found no perchlorate degradation as long as nitrate was present in the system, and perchlorate degradation initiated only after all the nitrate had been reduced. Nitrate-reduction rates were correlated to the initial concentrations of nitrate and no lag period was observed for nitrate reduction. Viable microbial populations were observed at both high concentrations (10,000 mg l^?1 and 20,000 mg l^?1) and with no addition of perchlorate, at levels of 2.35 × 10⁵, 4.01 × 10⁵, and 3.41 × 10³ CFU ml^?1, respectively; these results were well correlated to those found by PCR amplification analysis of chlorite dismutase. We suggest that the microbial community has adapted to the conditions of high perchlorate concentrations in the unsaturated zone over 30 years of exposure. When no external carbon source was added to the slurry of soil from land surface, all perchlorate was removed after 134 days of incubation. The average perchlorate-reduction rate using natural organic matter as a carbon source was 0.45 mg day^?1, while the average rate using acetate as an external carbon source was 7.2 mg day^?1.     

Organic compounds in soils and sediments from unlined waste disposal pits for natural gas production and processing

Samples of soil in dry waste pits and of sediment from waste pits currently in-use for natural gas production in the San Juan Basin of northwest New Mexico were collected for characterization of the presence and concentration of organic compounds. Samples were dried at 25 °C and about 50 g were extracted successively in a Soxhlet apparatus using hexane, benzene, and methanol. Extracts were filtered and condensed to 10 mL. Analyses of hexane extracts of samples using high-resolution gas chromatography showed presence of a complex mixture of 40 to 50 organic compounds in dry soil and in sediment from in-use pits. The range of size for compounds was C₁₀ to C₂₅. Although no compounds were detected in GC analyses of subsequent benzene and methanol extracts of the same soil samples, these extracts were highly colored and contained 5 to 10% of total absorptivity at 254 nm. Total extractable residues in the hexane extracts ranged from 49 to 110 mg g^?1 of soil. Polycyclic aromatic hydrocarbons were detected in hexane extracts at concentrations of 270 to 870μg g^?1 of dry sample.