Removal of SO4, uranium and other heavy metal ions from simulated solution by sulfate reducing bacteria

In the case of in-situ leaching of uranium, the primitive geochemical environment for groundwater is changed since leachant is injected into the water bearing uranium deposit. This increases the concentration of SO4^2-, uranium and other heavy metal ions and results in the groundwater contamination. The effects of pH values of the simulated solution on the reduction of SO4^2- and the removal of uranium and other heavy metal ions by sulfate reducing bacteria（SRB） were studied. The results show that, when the pH value of the simulated solution is about 8, the reduction rate of SO4^2- by SRB and the removal rate of uranium, Mn^2＋, Zn^2＋, Pb〉 and Fe^2＋ will reach their highest values. A bioremediation technique for remediation of groundwater in in-situ leaching uranium mine can be developed.     

石油污染物的微生物降解

从炼油厂污水池底泥中富集、驯化、分离、筛选,得到4种优势石油降解菌。采用摇床培养,研究了各优势 菌和混合菌对石油烃的降解性能。结果表明:4种菌和混合菌20d可将初始质量浓度为10000mg/L的石油烃 依次降解90.8%、88.9%、57.8%、49.8%、91.2%;培养液中石油烃的半衰期依次为5.5、6、15、19、5d。初 步鉴定4种菌分别属:节细菌(Arthrobactersp.)、芽胞杆菌(Bacillussp.)、不动杆菌(Acinetobactersp.)、不动 杆菌(Acinetobactersp.)。     

Comparative Study of Structural Changes of Polylactide and Poly(ethylene terephthalate) in the Presence of Trichoderma viride

Plastic pollution is one of the crucial global challenges nowadays, and biodegradation is a promising approach to manage plastic waste in an environment-friendly and cost-effective way. In this study we identified the strain of fungus Trichoderma viride GZ1, which was characterized by particularly high pectinolytic activity. Using differential scanning calorimetry, Fourier-transform infrared spectroscopy techniques, and viscosity measurements we showed that three-month incubation of polylactide and polyethylene terephthalate in the presence of the fungus lead to significant changes of the surface of polylactide. Further, to gain insight into molecular mechanisms underneath the biodegradation process, western blot hybridization was used to show that in the presence of poly(ethylene terephthalate) (PET) in laboratory conditions the fungus produced hydrophobin proteins. The mycelium adhered to the plastic surface, which was confirmed by scanning electron microscopy, possibly due to the presence of hydrophobins. Further, using atomic force microscopy we demonstrated for the first time the formation of hydrophobin film on the surface of aliphatic polylactide (PLA) and PET by T. viride GZ1. This is the first stage of research that will be continued under environmental conditions, potentially leading to a practical application.     

Diesel Oil Degradation Potential of a Bacterium Inhabiting Petroleum Hydrocarbon Contaminated Surface Waters and Characterization of Its Emulsification Ability

Degradation of poorly water soluble hydrocarbons, like n‐alkanes and polycyclic aromatic hydrocarbons are challenged by some bacteria through emulsification of hydrocarbons by producing biosurfactants. In diesel oil bioremediation, diesel oil degrading and surfactant producing bacteria are used to eliminate these pollutants from contaminated waters. Therefore, identifying and characterizing bacteria capable of producing surfactant and degrading diesel oil are pivotal. In this study, bacteria isolated from hydrocarbon contaminated river water were screened for their potential to degrade diesel oil. Primary selection was carried out by using conventional enrichment culture technique, emulsification index measurement, gravimetric and gas chromatographic analyses of diesel oil degradation. A bacterium with 60 % emulsification index and 92 % diesel oil degradation ability in 14 days was identified as Acinetobacter haemolyticus Zn01 by 16S rRNA sequencing. A. haemolyticus Zn01 was shown to harbor both catabolic genes alkB and C23O effective in diesel oil degradation. The biosurfactant of the bacterium was also characterized in terms of surface tension, zeta potential, Fourier transform infrared spectroscopy and scanning electron microscopy. Being able to emulsify and degrade diesel oil, A. haemolyticus Zn01 seems to have high potential for the elimination of diesel oil from polluted waters.     

A reactor model for pulsed pumping groundwater remediation

A hybrid in situ bioremediation/pulsed pumping strategy has been developed to cost effectively remediate a carbon tetrachloride plume in Schoolcraft, Michigan. The pulsed pumping system uses a line of alternating injection and extraction wells perpendicular to the direction of natural groundwater flow. The wells pump periodically to clean the recirculation zone between adjacent wells. During the pump-off phase, natural groundwater flow brings new contaminant into the recirculation zone. The wells are pumped again prior to breakthrough of contaminant from the recirculation zone. A computationally efficient reactor model has been developed, which conceptually divides the aquifer into injection, extraction, and recirculation zones, which are represented by a network of chemical reactors. Solute concentration histories from three-dimensional finite difference simulations and from field data confirm the reactor model predictions. The reactor model is used to investigate the optimal well configuration, pumping rate, and pumping schedule for achieving maximum pollutant degradation.     

重金属污染土壤的植物修复技术

重金属污染后的土壤严重威胁着环境安全,植物的土壤修复技术是当前的研究热点。利用植物的萃取、挥发、稳定、根系过滤等不同方法对土壤中的重金属吸收富集,达到去除重金属的目的。土壤的性质和重金属在土壤中的存在形态是影响超富集植物吸收富集重金属的影响因素。植物修复技术是新兴高效、绿色廉价的修复途径,具有良好的经济和生态综合效益。     

耐热石油降解混合菌群的降解性能研究

针对极端环境下石油污染土壤的生物修复,从克拉玛依油田石油污染土壤中筛选获得一组最适生长温度为45～55℃、最高耐受温度为75℃的耐热石油降解混合菌群KLO-8,该混合菌群由4株单菌组成,16S rDNA序列分析鉴定表明,其中3株为芽孢杆菌(Bacillus sp.)、1株为地芽孢杆菌(Geobacillus sp.)....     

SDBS残留对微生物修复石油污染土壤的影响

为探究表面活性剂清洗对微生物修复石油污染土壤的影响,模拟实际石油污染土壤微生物修复,考察不同十二烷基苯磺酸钠(SDBS)添加量的土壤修复过程中总石油烃降解率的变化情况,探究了SDBS对微生物修复石油污染土壤效果的影响;比较了不同微生物法修复石油污染土壤的实验方案,确定了最佳微生物修复方式。结果表明：少量的SDBS残留对后续微生物修复有促进作用,但SDBS残留质量分数大于1 mg/g时,则不宜于石油污染土壤的生物修复;土著菌+秸秆固定化微生物和土著菌+游离高效降解菌+秸秆2种修复方式,启动快,降解率的增速大,修复效率高,可以实现石油污染土壤快速和持续修复。