Remediation of contaminated soil using soil washing and biopile methodologies at a field level

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.     

不同类型表面活性剂增效去除焦化厂污染土壤中多环芳烃的研究

Surfactant enhanced remediation is thought to be an effective method for the remediation of soils polluted with hydrophoblc organic compounds. Desorption of polycyclic aromatic hydrocarbons （PAHs） from an abandoned manufactured gas plant （MGP） soil was evaluated using four eluting agents including Triton X-100 （TX100）, sodium dodecylbenzene sulfonate （SDBS）, rhamnolipid water solution （RWS） and rhamnolipid fermentation broth （RFB）. The weight solubilization ratios for acenaphthene and fluorene were in the order of TX100 〉 SDBS 〉 RWS 〉 RFB. The Sm value, which indicates the maximum amounts of surfactants adsorbed in the soil, was in the order of RWS 〉 RFB 〉 SDBS 〉 TX100. By using 8 g L-1 of TX100, SDBS and RWS and 100% of RFB, the T-PAHs removal for the MGP soil contaminated with 207.86 mg T-PAHs kg-1 dry soil was 48.0%, 45.7%, 1.9%, and 8.6%, respectively, while that decreased to 41.6%, 37%, 0.38%, and 1.3% for the soil contaminated with 3494.78 mg T-PAHs kg-1 dry soil. Only 8 g L-1 TX100 could remove all types of the 16 PAHs partly in the MGP soil, and the removal efficiencies of different PAHs ranged from 13% to 77.8%. The results of this study herein provide valuable information for the selection of TX100 surfactant for remediating PAH-contaminated soils in MGP.     

Contamination by PAHs,PCBs, PCPs and heavy metals in the mecoácfin lake estuarine water and sediments after oil spilling

Intention, Goal, Scope, Background  Environmental pollution caused by oil spills is a major ecological problem. Oil contamination in the environment is primarily evaluated by measuring the chemical concentrations of hydrocarbons. The results of chemical analyses are important for estimating water and sediment quality in the risk assessment to the flora and fauna of oil-contaminated sites. In the world there are lake ecosystems under permanent chemical stress due to urbanization and the oil industry. Studies, however, have been generally limited to petroleum compounds and have not considered other pollutants of the site like PCBs, polychlorinated pesticides and heavy metals. Objective  Water and sediment from stations in the Mecoacán Lake in the Mexican State of Tabasco were analyzed for polycy-clic aromatic compounds (PAHs), aliphatic hydrocarbons (AHs), polychlorinated biphenyls (PCBs), polychlorinated pesticides (PCPs) and heavy metals. The objective of this study was to examine the contaminant levels of the samples collected in February 1993 and 1996 after oil spills at the Mecoacán petroleum region. The goals of this study were to reveal the effect of the spills on the distribution of the hydrocarbons and assess the toxi-cological significance of the levels found. In addition, our aim was to examine the distribution of the PAHs in sediments from Mecoacán originated from both pyrolytic and petrogenic sources. Methods  Samples were collected from 19 stations and prepared according to the CARIPOL (Caribbean Pollution) methodology of the United Nations Environmental Programme (1992) of the Great Caribbean Region for hydrocarbons in marine and coastal water, and sediments. The gas-chromatographic and atomic absorption analysis of the samples was performed after sampling. Results and Discussion  Concentrations of PAHs in water ranged from 0.2 to 0.8 μg/l in 1993 and from 0.3 to 2.8 μg/l in 1996. The concentration of the 16 EPA-PAHs varied from 0.1 to 36 mg/kg dry weight in the lake sediment samples collected in 1996, while those of AHs, PCBs and PCPs ranged from 0.1 to 67 mg/kg, 0.1 to 59 μg/kg and 6 to 370 μg/kg, respectively. The most abundant contaminants in water were benz[a]anthracene and pyrene, in 1993 and 1996, respectively; while in sediments collected in 1996: Pyrene, C₂₄, 2-chlorobiphenyl and endrin predominated. Heavy metals (Cu, Pb and Zn) were found at low concentrations. Benzo[a]pyrene was detected in some sediment samples in varying amounts (0.2 to 0.3 mg/kg). Conclusions  The maximum total PAH concentration in sediments was found at sites near the oil fields and the AH concentration near the urban zone. The mayor pollutants in sediments were PAHs and AHs, and taking into regard the detected PAHs near the oil fields, the source was the oil spilling. The mean total PAH value in Mecoacan sediments of 6.4 mg/kg did not exceed the median range effects value (ERM) for total PAHs of 44.8 mg/kg. The measured organochlorine compounds and heavy metals were present in amounts much inferior to the ERM values. This study confirms that contaminants concentration in sediments did not exceed the environmental quality guideline for the 50% probability and no adverse effect can be expected. Recommendation and Outlook  Analysis revealed no indication of a contribution of PAHs, PCBs, PCPs and heavy metals to acute sediment toxicity. The results of this study demonstrate the importance of continuous monitoring of ecosystems exposed to pollution to make pre-spill data available in order to evaluate the real consequence of the spilling and its effect on flora and fauna.     

甜菜与牧草间作对多环芳烃污染土壤的修复作用

通过盆栽试验方法,选择经济作物甜菜和牧草类黑麦草、苏丹草、香根草为供试植物,研究了甜菜与3种牧草分别间作及各自单作对多环芳烃（PAHs）菲、荧蒽、芘和苯并[a]芘污染土壤修复作用。结果显示：经6个月连续两茬种植试验后,所有种植植物的处理中土壤PAHs的去除率均高于无植物种植组,间作种植土壤PAHs的去除率高于单作,黑麦草、苏丹草、香根草与甜菜间作对土壤PAHs的去除率分别达到84.85%、79.96%、84.11%;在土壤污染条件下,间作模式更有利于甜菜生长;种植植物增强了土壤中多酚氧化酶和过氧化氢酶的活性,间作模式下二者活性高于单作4.37%~43.07%,过氧化氢酶较多酚氧化酶对PAHs土壤污染更敏感,可作为关键酶用于评价土壤PAHs污染状况。在不影响农业生产的前提下,修复植物牧草和经济作物甜菜间作种植模式显著提高了土壤PAHs的降解率。     

生物质炭中的污染物含量及其田间施用的环境风险预测

生物质炭在碳固定、污染修复和酸性土壤改良中的应用非常广泛,但对生物质炭中所含污染物的研究甚少,其在田间应用中的环境风险并不清楚。该文选择松针和麦秆为原料,采用不同制备方法,研究了不同条件下获得的生物质炭中的重金属和多环芳烃含量,并初步评估了其田间应用的环境风险。研究表明,不同有机废弃物来源制备的生物质炭中均含有一定量的重金属(0.301～128mg/kg)和多环芳烃(1.48～5.48mg/kg);松针制备的生物质炭中的重金属含量普遍高于麦秆制备的生物质炭,而多环芳烃含量则相反,且高温制备有助于降低生物质炭中的多环芳烃含量;在低施用量的田间条件下,生物质炭的施用不易对土壤造成多环芳烃的环境风险,但在高施用量条件下,生物质炭中含有的多环芳烃容易使土壤中多环芳烃含量达到中度或重度污染的程度;生物质炭中的重金属在土壤中的积累量比较有限,环境风险较小。     

Polycyclic Aromatic Hydrocarbons, Polychlorinated Biphenyls and Trace Metals in Sediments from a Coastal Lagoon (Northern Adriatic, Italy)

Surface sediments (0–5 cm) were analysed to provide information on levels, spatial trends and sources of the 16 USEPA polycyclic aromatic hydrocarbons (PAH), 15 polychlorinated biphenyls (PCBs) and trace metals (copper, chromium, mercury, nickel and zinc) in channel and wetland habitats of Pialassa Baiona lagoon (Italy). The highest levels of PAHs, PCBs and Hg (3,032–87,150, n.d.–3,908 and 1.3–191 mg kg⁻¹) were mainly found at channel habitats close to industrial sources. Pyrogenic PAH inputs were significant, with a predominance of four-ring PAHs and combustion-related PAHs in both channel and wetland habitats. Among PCB congeners, chlorination class profiles show that penta- and hexachlorinated PCBs are the most prevalent homologues accounting for approximately 33% and 47% of the total PCB concentrations in channel sediments. Total toxicity equivalent factors (TEQs) of potentially carcinogenic PAHs varied from 348 to 7,879 μg kg⁻¹ and from 4.3 to 235 μg kg⁻¹ in channel and wetland sediments; calculated TEQs for dioxin-like PCB congeners at channel habitats ranged from n.d. to 86.7 μg kg⁻¹. Comparison of PAHs, PCBs and metal levels with Sediment Quality Guidelines suggests that more concern should be given to the southern area of the lagoon for potential risks of carcinogenic PAHs, dioxin-like PCBs and mercury.     

酸碱调控对泥浆反应去除土壤中多环芳烃的影响研究

采用摇瓶试验模拟研究了酸碱调控对泥浆反应去除污染土壤中多环芳烃的影响,结果表明,泥浆反应对污染土壤中的多环芳烃具有一定的去除效果,长期污染土壤中多环芳烃的去除率为10.6% ~ 20.7%,模拟污染土壤中的去除率为37.4% ~ 42.1%;酸碱调控对不同性质的多环芳烃的去除影响不同,整体上看,酸性条件有利于高环（五环和六环）多环芳烃的去除,而中性条件有利于低环（三环和四环）多环芳烃的去除。在实际修复中,根据污染土壤中多环芳烃的组成进行适当的酸碱调控,可以促进污染土壤的快速修复。     

接种丛枝菌根真菌的种植紫花苜蓿土壤中球囊霉素含量与去除的关系

以菲和芘为多环芳烃（PAHs）代表物,以紫花苜蓿（Medicago sativa L.）为宿主植物,选用幼套球囊霉（Glomus etunicatum, Ge）、摩西球囊霉（Glomus mosseae,Gm）和层状球囊霉（Glomus lamellosum,Gla）3种丛枝菌根真菌（AMF）,研究了接种AMF下土壤中AMF菌丝密度、球囊霉素含量与PAHs去除率的关系。35~75 d,接种Ge、Gm、Gla处理的土壤中菌丝密度、总球囊霉素含量、易提取球囊霉素含量均随时间延长而显著增大,与不接种对照相比,75 d时接种Ge、Gm、Gla处理的土壤中易提取球囊霉素含量提高了48.58%、55.99%和50.23%,总球囊霉素含量则提高了38.75%、50.95%和46.12%。接种AMF促进了土壤中菲和芘的去除,随着时间（35~75 d）延长,接种Ge、Gm、Gla处理的土壤中菲去除率分别高达83.4%~92.7%、82.1%~93.8%、86.9%~93.4%,芘去除率达42.2%~63.5%、43.7%~69.2%、44.6%~66.4%。接种Ge、Gm和Gla处理土壤中AMF菌丝密度、总球囊霉素含量均与土壤中菲和芘的去除率之间存在极显著正相关关系,表明接种AMF提高了土壤中AMF菌丝密度和总球囊霉素含量,并促进了土壤中PAHs的去除。研究结果为阐明丛枝菌根修复PAHs污染土壤的规律及机理提供了依据。     

混合菌群强化去除泥浆体系中菲、芘的效果及影响因素

通过室内泥浆体系模拟试验,研究了混合微生物菌群(嗜热菌和多环芳烃特异性降解菌),在40℃条件下(两类微生物均能较快生长繁殖),对泥浆体系中代表性多环芳烃菲、芘的去除效果及其影响因素(水土比,葡萄糖、淀粉、水杨酸及其浓度)。结果表明:泥浆体系中混合微生物菌群对多环芳烃的去除效果显著(P0.01),单日菲去除率最大可达20.0%,芘达15.3%。随着反应进程的进行,菲和芘的去除率提高,去除速率则逐步降低,菲的半衰期1.8天小于芘4.9天,因此菲的去除较芘更快。试验得到该泥浆体系中混合微生物菌群去除多环芳烃最合适的水土比为2︰1,碳源为葡萄糖,浓度TOC_(葡萄糖):TOC_(PAHs)为2︰1。该研究结果可为泥浆体系中混合微生物菌群强化修复多环芳烃污染土壤的技术研发提供理论基础和技术支撑。     

Polycyclic Aromatic Hydrocarbons (PAHs) Slurry Phase Bioremediation of a Manufacturing Gas Plant (MGP) Site Aged Soil

Bench scale tests have been carried out in order to investigatebioremediation feasibility of a Manufacturing Gas Plant site(Bovisa Gasometri – MI – I) aged soil, highly contaminated bypolyaromatic hydrocarbons (PAHs) and mineral oils. Biodegradationstudies were carried out at 22 °C in a slurry system reactor, with a solid to liquid ratio of 10% w/w. Three testswere performed, over a period of 23, 24 and 91 days respectively.In the first test, only soil and water were put into the system.In the second test, microbial activity was inhibited to evaluatethe amount of abiotic losses. In the third test, macronutrientswere added to the reactor; bioaugmentation was also carried outby an inoculum of autochthonous PAH-degrading microorganisms. Saturated hydrocarbons, PAHs, transformation products, heterotropic and PAH-degrading bacteria and fungi were monitored.Tests showed that high removal efficiency could be obtained following 23 days of treatment for all PAHs, including high molecular weight compounds. Abiotic losses were an importantprocess contributing to concentration abatement in soil, especially in the first phase of the treatment. Lag time lackfor all polyaromatic hydrocarbons revealed that autochthonousmicroorganisms were well adapted to these contaminants; bioaugmentation did not seem to speed up the process. The higherremoval rate and efficiency for high molecular weight PAHs obtained in the third test suggested that nutrient addition could play an important role in the biodegradation process ofthese compounds, whereas it did not significantly modify total(abiotic + biotic) removal of light compounds.     

Biodegradation combined with ozone for the remediation of contaminated soils

The effectiveness of the SS-SBR (Soil Slurry – Sequencing Batch Reactor) process for the remediation of soils contaminated by several organic pollutants has been evaluated. Experimental tests have been performed on two different soils, a spiked one and an industrial aged soil. The spiked soil, artificially contaminated, has been prepared trying to simulate the pollution of an industrial aged soil in terms of number and kind of contaminants. PAHs (Polycyclic Aromatic Hydrocarbons) and phenols degradation has been particularly investigated because they are considered persistent and recalcitrant. Concerning the spiked soil, removal efficiencies higher than 95% in 6 to 9 weeks have been found for all the pollutants, except for five-rings PAHs; however, these compounds were partly removed in 11 to 13 weeks. Good results have been achieved also for the industrial aged soil with a maximum removal of about 80% in 7–8 weeks. To enhance the pollutants degradation, trying to obtain a faster remediation, the biological treatment has been combined with a chemical oxidation with ozone. The best degradation effectiveness of the combined process has been obtained applying the ozonation after few days of the biological treatment. Therefore, a combined biological and chemical treatment allowed to markedly improve the remediation of contaminated soils.     

双污泥反硝化除磷系统中氨氮容积负荷的优化

农村生活污水具有处理量小,分散,日变化系数大等特点,分散处理成为农村污水处理的首要选择。该研究采用AAO工艺与BAF组成的双污泥反硝化除磷系统（anaerobic anoxic oxic-biological aerated filter,AAO-BAF）处理农村生活污水,探讨了氨氮容积负荷对该系统BAF单元硝化性能及出水悬浮物（SS）的影响。通过改变水力负荷和有效滤料容积（即方式1和方式）2种方式,氨氮容积负荷在0.43～1.21 kg/(m3·d)之间变化。试验结果表明,随着氨氮容积负荷的增加,氨氮去除率呈现先缓慢降低后急剧减小的趋势,不同的是,出水SS对方式1（即水力负荷的变化）更敏感。当氨氮容积负荷在0.43～1.12 kg/(m3·d)时,氨氮去除率大于81%;当氨氮容积负荷大于1.12 kg/(m3·d),氨氮去除率急剧降低,氨氮容积负荷为1.21 kg/(m3·d),2种运行方式的氨氮去除率分别为65%和68%。当氨氮容积负荷小于0.74 kg/(m3·d)时,出水SS小于10 mg/L;当氨氮容积负荷大于0.74 kg/(m3·d)时,出水SS急剧增加,但方式1增加得更快,氨氮容积负荷增加到1.21 kg/(m3·d)时,方式1和方式2的出水SS分别为21.8和14.2 mg/L。所以,为保证BAF出水水质达到国家一级A排放标准,其氨氮容积负荷应小于0.74 kg/(m3·d)。     

Studying the Effects of Two Various Methods of Composting on the Degradation Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Sewage Sludge

The research comprised of studying the effect composting sewage sludge with sawdust and vermicomposting with earthworm Eisenia fetida has on the degradation of 16 polycyclic aromatic hydrocarbons (PAHs). Raw rural sewage sludge prior composting was more contaminated with PAHs than urban sewage sludge, in both cases exceeding EU cutoff limits of 6 mg/kg established for land application. Dibenzo[a,h]anthracene (DBahAnt), acenaphtylene (Acy) and indeno[1,2,3-c,d]pyrene (IPyr) were predominant in rural sewage sludge, whilst the urban sewage sludge contained the highest concentrations of benzo[b]fluoranthene (BbFl), benzo[k]fluoranthene (BkFl) and indeno[1,2,3-c,d]pyrene (IPyr). Thirty days of composting with sawdust has caused a significant reduction of 16 PAHs on average from 26.07 to 4.01 mg/kg (84.6%). During vermicomposting, total PAH concentration decreased on average from 15.5 to 2.37 mg/kg (84.7%). Vermicomposting caused full degradation of hydrocarbons containing 2 and 6 rings and significant reduction of PAHs with 3 aromatic rings (94.4%) as well as with 5 aromatic rings (83.2%). The lowest rate of degradation (64.4%) was observed for hydrocarbons with 4 aromatic rings such as fluoranthene, benzo(a)anthracene, chrysene and pyrene. On the other hand, the highest level of degradation was determined for PAHs with 2 rings (100%), 3 rings (88%) and 6 aromatic rings in the molecule (86.9%) after composting with sawdust. Acenaphthene and pyrene were found to be the most resistant to biodegradation during both composting methods.     

Polycyclic aromatic hydrocarbons and polychlorinated biphenyls in urban and semi-urban soils of Havana,Cuba

Purpose

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in Havana were quantified and analyzed in relation to possible emission sources to assess metropolitan soil contaminations in a highly dynamic, urban environment. The results of this study will serve Cuban legislators as a basis to develop environmental quality standards for organic pollutants in soils.

Materials and methods

Possible emission sources as, e.g., the vicinity to roads or industrial plants and the influence of the land use were related to the organic contaminants concentrations. Therefore, 28 topsoils in the Havana urban and semi-urban area were sampled at agricultural (n?=?12), organoponic (urban gardens in the capital, n?=?8), public park (n?=?7), and remediation (on-site bioremediation of an oil refinery, n?=?1) sites. Their PAH and PCB concentrations were measured with gas chromatography mass spectroscopy and the total organic carbon (TOC) and black carbon (BC) concentrations with the chemo-thermal oxidation.

Results and discussion

The sum of the 16 PAH concentrations ranged from 0.04 mg/kg in agricultural and organoponic soils to up to 72 mg/kg in a public park at about 1.5 km distance from an oil refinery. The lowest sum of the seven PCB congener concentrations was also measured in organoponic soils (0.002 mg/kg) and the highest in an arable patch of land between the rail roads and a main road (0.1 mg/kg). Both, PAH as well as PCB soil concentrations in Havana were almost up to two orders of magnitudes higher compared to a soil monitoring in the neighboring province of Mayabeque, but overall in the typical range of urban soils reported by other studies. The pollutants showed no relationship between TOC and BC except for PAHs with BC. For PAHs, combustion was the main source.

Conclusions

A comparison of the pollutant concentrations with regulatory guidance values (RGV) of other countries revealed PCB concentrations in Havana soils far below these RGV. In contrast, some concentrations of benzo[a]pyrene, the most carcinogenic PAH, in agricultural and park soils in Havana exceeded some RGV. Thus, some public parks pose a risk according to the Canadian quality guidelines when people have direct contact with these soils but not if they were consuming products thereof.

     

Polycyclic Aromatic Hydrocarbons Formation in Sludge Incineration by Fluidised Bed and Rotary Kiln Furnace

Polycyclic Aromatic Hydrocarbons (PAHs) are typical pollutants arising from incineration. They are produced in any incomplete combustion principally due to inhomogeneities in a combustion chamber. The effects of the afterburning temperature on PAHs formation during sewage sludge incineration are discussed in this paper. Tests were performed inside the area of the wastewater treatment plant of `Bari Ovest' on a demonstrative plant (maximum throughput 250 kg hr^-1 of dewatered sludge at 20% solids concentration) equipped with a fluidised bed furnace (FBF) and a rotary kiln furnace (RKF) where sewage sludge was fed, either as it was taken from the dewatering section of the wastewater treatment plant, or previously spiked by different dosages of chlorinated hydrocarbons. Exhaust gases were sampled before the bag filter, where the pollutants can be considered representative of those arising from the process. Parallel sampling of flue gas at the stack was also carried out. In the FBF tests with sludge spiked with high dosages of chlorinated hydrocarbons highest values of PAHs concentrations (>3.9 μg Nm^-3) were detected before filtration, when the afterburning chamber was not in use. The operation of the afterburning chamber, at a temperature higher than 900 °C, allows to partially suppress PAHs formation up to values of 0.9—3.2 μg Nm^-3. PAHs removal efficiency of the exhaust gas treatment was calculated with a mean value for all the test of 72%.In RKF tests PAHs displayed much lower values before filtration (range 0.04—2.98 μg Nm^-3, mean value 0.51 μg Nm^-3) probably due to the longer gas residence time in the furnace (>6 s in comparison with values <2 s in fluidised bed furnace). Surprisingly, for RKF tests PAHs removal efficiency of gas treatment appeared quite unstable: some tests evidenced PAHs stripping in the scrubber, where the effluent of the wastewater treatment plant was used. No correlation was observed in RKF tests between PAHs concentration before the bag filter and the temperature of the afterburning chamber.     

多环芳烃污染土壤表面活性剂清洗及生物柴油强化

针对某焦化厂内高浓度多环芳烃污染土壤,以烷基苷（APG）、十二烷基苯磺酸钠（SDBS）和曲拉通X-100（TX100）为表面活性剂代表物,采用静态平衡法和高效液相色谱分析,探索采用单一及混合表面活性剂清洗修复多环芳烃污染土壤,并考察生物柴油对多环芳烃去除效果的影响。结果表明,单一表面活性剂对土壤中多环芳烃去除率顺序为SDBS〉APG〉TX100。APG／SDBS混合处理及TX100/SDBS为9：1混合处理提高了土壤中多环芳烃去除率,而APG／TX100混合处理没能提高多环芳烃去除率。生物柴油对TX100及TX100／SDBS去除多环芳烃效果没有明显提高,对APG及APG/TX100去除多环芳烃略有提高。当APG／SDBS为9：1时,生物柴油可以使多环芳烃去除率从（63．3±2．0）％提高到（75．6±2．0）％。单一表面活性剂、混合表面活性剂、及表面活性剂-生物柴油乳液对多环芳烃各组分去除率比较类似,对菲的去除率最高,茚并[1,2,3-d]芘次之,其余相对较低。因此,建议采用APG／SDBS＋生物柴油的混合体系对高浓度多环芳烃污染土壤进行修复。     

不同还原条件下多环芳烃厌氧微生物降解研究：基于文献计量的剖析

厌氧微生物降解是环境中多环芳烃（polycyclic aromatic hydrocarbons,PAHs）污染削减的重要途径。为系统、全面地了解PAHs厌氧微生物降解的研究现状,以Web of Science核心数据库为数据源,对该领域已发表文献进行文献计量分析,并以厌氧环境中不同还原条件对应的电子受体还原体系为切入点,分别论述反硝化体系、金属离子还原体系、硫酸盐还原体系和产甲烷体系中的PAHs厌氧微生物降解的研究进展,在此基础上重点对土壤中PAHs厌氧微生物降解研究的现存理论空白和未来发展趋势进行探讨。分析结果表明,PAHs厌氧微生物降解领域的研究整体较少,其中,绝大多数仅针对低环PAHs;不同还原条件中对产甲烷和金属离子还原体系的关注也较少;已有研究多侧重纯培养物或水体、沉积物等环境介质,较少基于土壤展开,且新兴技术在该领域尚未得到广泛应用。因此,目前针对土壤中PAHs厌氧微生物降解的认识尚存在诸多理论空白。土壤是环境中PAHs汇集和积累的重要场所,未来应当尝试将单体稳定同位素分析、稳定同位素核酸探针、组学等多种新兴技术与传统研究方法相结合,从多种的角度深入探究土壤PAHs厌氧微生物降解的机制,并将已有的理论和经验在土壤中进行验证,以填补现存理论空白,推进厌氧土壤中PAHs污染微生物修复工作的开展。     

Microtox技术检测多环芳烃生物毒性的研究

利用Microtox技术检测 5种多环芳烃化合物生物毒性结果表明 ,二甲亚砜配制的测试液中萘、菲及荧蒽均对发光细菌具有一定生物毒性 ,且随浓度的增大而增强 ,相同浓度下毒性菲 >萘 ;测试液中当萘浓度小于其溶解度时即产生 10 0 %的抑光率 ,萘EC50 为 4 .32mg/L ,而菲及荧蒽浓度近其溶解度时所产生的最大抑光率分别为 <5 0 %和15 %左右 ;芘及蒽最大浓度时则对发光细菌无生物毒性显示。表明Microtox技术可有效检测低环化合物萘的生物毒性 ,但对高环化合物 (≥ 3环 )的检测因受其低水溶性的限制而灵敏度降低 ,利用二甲亚砜获取多环芳烃污染物提取液的生物毒性主要与低分子化合物萘及菲有关     

微生物降解石油源多环芳香烃的研究进展

石油源多环芳香烃是存在于石油中的一类致畸、致癌污染物,具有以低环(2~3环)为主且取代基比例明显高于其他来源PAHs的组分特征。石油泄露引发的PAHs污染,其降解主要依赖于微生物的活动。本文对能够降解PAHs的微生物种类、降解机理、代谢途径及编码基因进行了概述。从PAHs作为碳源的角度将微生物降解机理划分为能以PAHs为唯一碳源进行生长的降解机理和共代谢机理。对与PAHs有关的好氧和厌氧微生物降解途径及对应的编码基因簇进行了总结。自然界中细菌、放线菌、真菌及藻类都能够降解PAHs,由加氧酶催化的苯环羟基化和还原酶介导的苯环脱芳烃化是好氧和厌氧降解途径的关键步骤,与降解有关的pca,cat,paa,nah,nah-like和bcr基因簇则分别调控好氧和厌氧降解过程。这些进展有助于系统了解石油源PAHs的降解过程、微生物作用机理和分子遗传机制,为进一步利用微生物促进环境生物修复提供理论依据。     

Removal of polycyclic aromatic hydrocarbons from soil amended with biosolid or vermicompost in the presence of earthworms (Eisenia fetida)

Earthworms burrow through the soil thereby accumulating many lipophilic organic pollutants from the surrounding environment, so they could be used to remove polycyclic aromatic hydrocarbons (PAHs) from soil. Sterilized and unsterilized soil was contaminated with phenanthrene (Phen), anthracene (Anth) and benzo[a]pyrene (BaP), with or without added Eisenia fetida and biosolid or vermicompost. Concentrations of PAHs were monitored in soil and earthworms for 70 days. Removal of PAHs increased in soil with earthworms added as 91% of Anth, 16% BaP and 99% Phen was dissipated compared to 42%, 3% and 95% in unamended soil. The microorganisms in the gut of the earthworm contributed to PAHs removal and 100% of Phen, 63% of Anth and 58% of BaP was removed from sterilized soil with E. fetida added. Biosolid and to lesser extent vermicompost accelerated removal of PAHs from soil. Applying earthworms to a contaminated site might be an environmentally friendly way to remove hydrocarbons from soil. However, a limitation might be the cost of the large amounts of earthworms required to remove PAHs from soil and the necessity to supply them with sufficient substrate while maintaining the water content of the soil high enough for their normal functioning.