Bioremediation and reclamation of soil contaminated with petroleum oil hydrocarbons by exogenously seeded bacterial consortium: a pilot-scale study

Purpose  

Spillage of petroleum hydrocarbons causes significant environmental pollution. Bioremediation is an effective process to remediate petroleum oil contaminant from the ecosystem. The aim of the present study was to reclaim a petroleum oil-contaminated soil which was unsuitable for the cultivation of crop plants by using petroleum oil hydrocarbon-degrading microbial consortium.     

Evaluation of biosurfactants for crude oil contaminated soil washing

An evaluation of the ability of aqueous biosurfactant solutions (aescin, lecithin, rhamnolipid, saponin and tannin) for possible applications in washing crude oil contaminated soil was carried out. The biosurfactants behaviour in soil-water, water-oil and oil-soil systems (such as foaming, solubilization, sorption to soil, emulsification, surface and interfacial tension) was measured and compared with a well-known chemical surfactant (sodium dodecyl sulphate, SDS) at varying concentrations. Results showed that the biosurfactants were able to remove significant amount of crude oil from the contaminated soil at different solution concentrations for instance rhamnolipid and SDS removed up to 80% oil and lecithin about 42%. The performance of water alone in crude oil removal was equally as good as those of the other biosurfactants. Oil removal was due to mobilization, caused by the reduction of surface and interfacial tensions. Solubilization and emulsification effects in oil removal were negligible due to the low crude oil solubilization of 0.11%. Therefore, these studies suggest that knowledge of surfactants' behaviour across different systems is paramount before their use in the practical application of oil removal.     

Anaerobic PAH degradation in soil by a mixed bacterial consortium under denitrifying conditions

Polycyclic aromatic hydrocarbons (PAHs) are one of the main classes of contaminants in the terrestrial environment. Concentrations of biphenyl, fluorene, phenanthrene and pyrene were added to soil samples in order to investigate the anaerobic degradation potential of PAHs under denitrifying conditions. A mixed population of microorganisms obtained from a paddy soil was incubated for 20 days in anaerobic conditions in the presence of soil alone or with nitrate, adding, as electron donors, PAHs and, in some samples, glucose or acetate. At regular time intervals oxidation-reduction potential, PAHs concentration, microbial ATP and nitrate concentration into the solution were measured. Degradation trends for each hydrocarbon are similar under all conditions, indicating that the molecular conformation prevails over other parameters in controlling the degradation. Poor degradation results were obtained when PAHs were the only organic matter available for the inoculum, thus confirming the recalcitrance to degradation of these compounds. Biodegradation was influenced by the addition of other carbon sources. As better degradation results were generally obtained when acetate or glucose were added, the hypothesis of a co-metabolic enhancement of PAH biodegradation seems likely. Thus, anaerobic biodegradation of PAHs studied, biphenyl, fluorene, phenanthrene and pyrene, seems to be possible both through fermentative and respiratory metabolism, provided that low molecular weight co-metabolites and suitable electron acceptors (nitrate) are present.     

表面活性剂强化甲基营养型芽孢杆菌修复柴油污染土壤

使用吐温80（Tween80）、鼠里糖脂（RL）、十二烷基苯磺酸钠（SDBS）和十二烷基苯硫酸钠（SDS）强化甲基营养型芽孢杆菌（Bacillus methylotrophicus）修复柴油污染土壤,研究了表面活性剂对甲基营养型芽孢杆菌的影响。结果表明：甲基营养型芽孢杆菌可以较好地降解柴油,但由于土壤的吸附,土壤中柴油的修复效率较低,仅为22.68%;因此,需要使用表面活性剂进行强化。浓度为3 000 mg·L-1的SDBS和SDS、2 000 mg·L-1的Tween80、500 mg·L-1的RL具有较好的洗脱效果。微生物毒性实验表明,Tween80和RL对甲基营养型芽孢杆菌具有促进作用,可以用于强化修复柴油污染土壤。2 000 mg·L-1 Tween80强化甲基营养型芽孢杆菌修复柴油土壤的修复效果（46.11%）优于500 mg·L-1 RL的修复效果（45.32%）,同时具有较好的经济性,具有较好的应用前景。     

Analytical study of Asthart crude oil asphaltenes biodegradation

Various analyses of an asphaltenic fraction of Asthart crude oil enabled us to show that it was partially degraded by a marine mixed bacterial population with saturated hydrocarbons as cosubstrate. We also gave evidence of its strong biotransformation rate and tried to correlate its evolution with the nature of the produced fractions.     

生态堆技术修复老化油泥污染土壤

通过添加海藻酸钠包埋菌剂、缓释肥料,并辅以通风工艺及浇水设备建立了修复石油污染土壤的生态堆,对胜利油田一处油泥暂存点的石油污染土壤进行了生态堆修复。修复结果显示：生态堆能高效修复污染土及油泥中的石油烃,一年后,C6~C16的脂肪烃降解至检出限以下,C17~C36的脂肪烃一年内降解率为93.5%,总PAHs的降解率能达到78%以上,但随着PAHs苯环数的增加,降解率呈下降趋势;缓释肥料及包埋菌剂的添加,以及生态堆顶部植物的种植,使生态堆内的环境条件保持较为稳定的状态,为石油烃的降解创造良好的条件。     

影响原油生物降解因素的实验研究

以原油为唯一碳源,从长期被石油污染土壤中筛选出6株原油降解菌SY1~SY6,通过单因素实验研究初始pH、温度、充氧量(摇床转数)、盐浓度、氮源和磷源等环境因素和营养条件对各菌株生物降解原油的影响。实验结果表明:6株原油降解菌在初始pH7~9,温度30℃,摇床转速180 r/min时生长良好,且能有效地降解石油类污染物,其平均降解率为50%以上。6菌株在盐浓度在1%时生长良好,SY3菌和SY4菌能在盐浓度10%以上生长,具有一定的耐盐能力。同时,6菌株以氯化铵(NH4Cl)为氮源,磷酸氢二钾(K2HPO4)和磷酸二氢钾(KH2PO4)的混合物(2∶1)为磷源时生长良好,因此可作为各菌生长的最适氮源和磷源。研究结果可以为含油废水的处理提供微生物基础。     

生物柴油促进原油污染砂粒释放油

对4种生物柴油促进原油污染砂粒释放油的效果进行了研究,并探讨了菜籽生物柴油投加量和砂粒粒径对促进效果的影响。结果表明,菜籽生物柴油的促进效果最好,8 h释放量达到73%,废油脂生物柴油的效果最差,仅为52%;生物柴油的促进效果随着投加量的增大而升高,当投加量超过海水体积的5%时促进效果不再明显增加;在生物柴油作用下,小粒径砂粒上原油的释放效果优于大粒径砂粒。     

Role of cyanobacteria in the biodegradation of crude oil by a tropical cyanobacterial mat

Cyanobacterial mats are ubiquitous in tropical petroleum-polluted environments. They form a high biodiversity microbial consortium that contains efficient hydrocarbons degraders. A cyanobacterial mat collected from a petroleum-contaminated environment located in Indonesia was studied for its biodegradation potential. In the field, the natural mat was shown to degrade efficiently the crude oil present in the environment. This natural mat demonstrated also a strong activity of degradation on model crude oil under laboratory conditions. In axenic cultures, the monospecific cyanobacterium Phormidium animale that constitute the bulk of the biomass did not exhibit any degradative capacity on hydrocarbons in the range of C13-C35 carbon atom number either in autotrophic or heterotrophic conditions. It was concluded that this cyanobacterial strain living on a heavily contaminated site had no direct effect on biodegradation of crude oil, the degradation activity being exclusively achieved by the other microorganisms present in the microbial consortium of the mat.     

PCB congener selective biodegradation by the white rot fungus Pleurotus ostreatus in contaminated soil

Six strains of white rot fungi were tested for their biodegradation ability of low chlorinated polychlorinated biphenyl (PCB) commercial mixture (Delor 103) in real soil system. Phanerochaete chrysosporium and Trametes versicolor did not show any ability to degrade PCBs in soil. On the contrary, four strains of Pleurotus ostreatus were able to remove about 40% of Delor 103 in two months. All P. ostreatus strains decomposed PCBs selectively with the preference for congeners with chlorine atoms in ortho > meta > para position. Degradation efficiency decreased with increasing number of chlorination.     

Assessment of crude oil biodegradation in arctic seashore sediments: effects of temperature,salinity, and crude oil concentration

The expected increase in offshore oil exploration and production in the Arctic may lead to crude oil spills along arctic shorelines. To evaluate the potential effectiveness of bioremediation to treat such spills, oil spill bioremediation in arctic sediments was simulated in laboratory microcosms containing beach sediments from Barrow (Alaska), spiked with North Slope Crude, and incubated at varying temperatures and salinities. Biodegradation was measured via respiration rates (CO₂ production); volatilization was quantified by gas chromatography/mass spectrophotometry (GC/MS) analysis of hydrocarbons sorbed to activated carbon, and hydrocarbons remaining in the sediment were quantified by GC/flame ionization detector (FID). Higher temperature leads to increased biodegradation by naturally occurring microorganisms, while the release of volatile organic compounds was similar at both temperatures. Increased salinity had a small positive impact on crude oil removal. At higher crude oil dosages, volatilization increased, however CO₂ production did not. While only a small percentage of crude oil was completely biodegraded, a larger percentage was volatilized within 6–9 weeks.     

Construction of bacterial consortium for efficient degradation of mixed pharmaceutical dyes

Environmental Science and Pollution Research - Synthetic dyes are established colorants in the pharmaceutical industries for the coating and coloration of tablets, capsules, etc. to mark the...     

热水洗辅助微生物修复高含油落地油泥

为解决油田落地油泥含油率高但不能直接进行生物无害化处置的问题,探索一种热水洗辅助微生物修复工艺。利用热水洗实验考察了清洗配方和水温对降低含油率的影响;从落地油泥中分离出石油烃降解菌,以用于含油残砂的微生物降解过程,同时探究填料和烃降解微生物对残砂中石油烃降解效果的影响。结果表明,鼠李糖脂清洗剂在总用量为0.5%、水洗时间30 min和50 ℃条件下,可将油泥含油率由107.1 mg·g⁻¹降至为39.3 mg·g⁻¹;水洗后残砂中的土著菌群数量出现了明显下降。分离获得了2株烃降解菌,并优选出具有增加油泥溶氧和保水的沼渣。将烃降解微生物和优选沼渣加入残砂后,石油烃生物降解效率得到显著提升,200 d后含油率降为4.62 mg·g⁻¹。在此过程中,微生物优先降解分子量小的饱和烃和芳香烃组分,对胶质和沥青质等组分降解程度偏低。该研究结果可为油田高含油落地油泥的环保处置提供参考。     

Solvent extraction for heavy crude oil removal from contaminated soils

A new strategy of heavy crude oil removal from contaminated soils was studied. The hexane-acetone solvent mixture was used to investigate the ability of solvent extraction technique for cleaning up soils under various extraction conditions. The mixtures of hexane and acetone (25 vol%) were demonstrated to be the most effective in removing petroleum hydrocarbons from contaminated soils and approx 90% of saturates, naphthene aromatics, polar aromatics, and 60% of nC₇-asphaltenes were removed. Kinetic experiments demonstrated that the equilibrium was reached in 5 min and the majority of the oil pollutants were removed within 0.5 min. The effect of the ratio between solvent and soil on the extraction efficiency was also studied and results showed that the efficiency would increase following the higher solvent soil ratio. Then the multistage continuous extraction was considered to enhance the removal efficiency of oil pollutants. Three stages crosscurrent and countercurrent solvent extraction with the solvent soil ratio 6:1 removed 97% oil contaminants from soil. Clearly the results showed that the mixed-solvent of hexane and acetone (25 vol%) with character of low-toxic, acceptable cost and high efficiency was promising in solvent extraction to remove heavy oil fractions as well as petroleum hydrocarbons from contaminated soils.     

微波修复石油污染土壤升温特性影响因素的实验研究

实验研究了微波功率、土壤受污染程度和各种吸波介质对微波修复石油污染土壤升温特性的影响,所用的吸波介质有水、颗粒活性炭、铝、镍、三氧化二钴、三氧化二铬和氧化锡.实验中以氮气为保护气微波辐照各种石油污染土壤样品,测量样品的升温特性.实验结果表明:(1)随着微波加热功率的增加,石油污染土壤的升温速率和最高温度都增大,功率从4...     

Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added ¹³C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass.     

Chemical oxidation of cable insulating oil contaminated soil

Leaking cable insulating oil is a common source of soil contamination of high-voltage underground electricity cables in many European countries. In situ remediation of these contaminations is very difficult, due to the nature of the contamination and the high concentrations present. Chemical oxidation leads to partial removal of highly contaminated soil, therefore chemical oxidation was investigated and optimized aiming at a subsequent bioremediation treatment. Chemical oxidation of cable oil was studied with liquid H₂O₂ and solid CaO₂ as well as permanganate at pH 1.8, 3.0 and 7.5. Liquid H₂O₂ most effectively removed cable oil at pH 7.5 (24%). At pH 7.5 poor oil removal of below 5% was observed with solid CaO₂ and permanganate within 2 d contact time, whereas 18% and 29% was removed at pH 1.8, respectively. A prolonged contact time of 7 d showed an increased oil removal for permanganate to 19%, such improvement was not observed for CaO₂.Liquid H₂O₂ treatment at pH 7.5 was most effective with a low acid use and was best fit to a subsequent bioremediation treatment. To further optimize in situ chemical oxidation with subsequent bioremediation the effect of the addition of the iron catalyst and a stepwise liquid H₂O₂ addition was performed. Optimization led to a maximum of 46% cable oil removal with 1469 mM of H₂O₂, and 6.98 mM Fe(II) chelated with citric acid (H₂O₂:FeSO₄ = 210:1 (mol mol⁻¹). The optimum delivery method was a one step addition of the iron catalyst followed by step wise addition of H₂O₂.     

Surfactant-enhanced release of carbaryl and ethion from two long-term contaminated soils

The potential of five nonionic surfactants, Triton X-100, Brij35, Ethylan GE08, Ethylan CD127, and Ethylan CPG660 for enhancing release of carbaryl and ethion from two long-term contaminated soils was evaluated using the batch method. Incorporation of the surfactants into soils enhanced the release of both pesticides to various extents, which could be related to the type of pesticides and type and the amount of surfactants added. Release of ethion was dramatically enhanced by aqueous concentrations of surfactants above their critical micelle concentration values. This was attributed to solubility enhancement through incorporation of the highly hydrophobic compound within surfactant micelles. A concentration of 10 g L(-1) of various surfactants released >70% of the total ethion from the soil irrespective of the surfactant. For carbaryl, the surfactants were effective at low concentrations and dependence on concentration was lower than in the case of ethion. The ethylan surfactants (GE08, CD127, and CPG660) had a higher potential than Triton X-100 and Brij35 for releasing the pesticides. However, there was still a significant portion of carbaryl (11% of the total) and ethion (17% of the total) left in the soil. Our study also showed that there must be an optimal concentration of each surfactant to maximize the mass transfer of pesticides. At some threshold concentration level, additional surfactant started to inhibit the mass transfer of solute from the soil into the water. The results suggested that surfactants could help remediation of soils polluted by pesticides. The choice of surfactant should be made based on the properties of pesticides.     

Bioremediation assessment,hematological, and biochemical responses of the earthworm (Allolobophora caliginosa) in soil contaminated with crude oil

Environmental Science and Pollution Research - Soil contamination with crude oil is a major environmental problem. The aim of this study was to assess whether the earthworm Allolobophora caliginosa...     

Biodegradation of dibromoneopentyl glycol by a bacterial consortium

Dibromoneopentyl glycol (DBNPG) is a brominated flame retardant that is used as an additive during the manufacture of plastic polymers and as a chemical intermediate for other flame retardants. It is classified as not readily biodegradable and based on experimental studies in animals is believed to be a carcinogen. We have demonstrated, to the best of our knowledge for the first time, the complete biodegradation of DBNPG under aerobic conditions. Total organic carbon (TOC) analysis indicates the complete mineralization of DBNPG. DBNPG biodegradation was accompanied by the release of bromide into the medium, probably due to a biological debromination reaction by bacterial consortia. A denaturing gradient gel electrophoresis (DGGE) analysis of PCR amplified 16S rRNA gene was used, to characterize the bacterial consortia involved in DBNPG biodegradation. At least seven bacterial species were found to be involved in this process, among them species with similarity to strains that are known for their dehalogenating ability.