地下水—土壤原位生物修复技术研究进展

简要介绍地下水-土壤原位生物修复技术原理,分析了地下水-土壤原位修复技术影响因素,综述了国内外关于溶解氧的输送方法以及有机污染物在地下水-土壤中的迁移转化规律等方面的研究进展,指出了地下水-土壤原位生物修复技术的研究方向。     

Sporosarcina pasteurii诱导碳酸盐-铀共沉淀修复低浓度铀废水的试验研究

对有钙源条件下Sporosarcina pasteurii诱导碳酸盐-铀共沉淀修复低浓度铀废水的性能开展了试验研究。试验结果表明,该细菌能分泌脲酶水解尿素诱导产生方解石并促使其与铀发生共沉淀,使废水中铀的去除率达到95.38%;该细菌能够耐受的铀浓度高达500 mg/L;铀的去除率随Ca²⁺浓度的升高而增加;温度在30℃左右和碱性环境有利于方解石与铀的共沉淀。对沉淀产物进行XRD、SEM-EDS表征分析表明,其主要成分为方解石,且包含铀元素;消解分析表明,在方解石形成过程中铀以共沉淀的方式被固定到了沉淀产物中。本研究表明,Sporosarcina pasteurii诱导碳酸盐-铀共沉淀对修复低浓度铀废水有潜在应用前景。     

AM真菌和牛粪对铅污染土壤的修复效应

铅污染会对环境和人体健康产生较大风险,如何修复污染土壤、降低农产品中的铅残留值得深入研究。在温室盆栽条件下研究了接种丛枝菌根(AM)真菌、施加牛粪及复合处理对铅污染土壤的修复效应和机理。结果表明,在所有铅污染水平下,接种AM 真菌、施加牛粪和复合处理均显著促进烟草生长,改善烟草磷营养。复合处理在所有铅污染水平下均降低烟草铅残留量,而施加牛粪仅在轻度和中度铅污染水平下、接种AM 真菌仅在重度污染水平下作用显著。土壤pH 升高,铅有效性降低。可见,AM 真菌和有机肥对铅污染地区优质烟叶生产及铅污染土壤的植物修复具有一定的应用潜力。     

Microbial aspects of acid mine drainage and its bioremediation

The role of chemolithotrophs such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans which were isolated from some abandoned mines and processed waste tailings in the generation of acid mine drainage and toxic metal dissolution was discussed. Mechanisms of acid formation and dissolution of copper, zinc, iron and arsenic from copper, lead-zinc and arsenopyrite-bearing sulfide ores and railings were established in the presence of Acidithiobacillus group of bacteria. Sulphate Reducing Bacteria（SRB） isolated from the above mine sites could be used to precipitate dissolved metals such as copper, zinc, iron and arsenic. Arsenic bioremediation was demonstrated through the use of native microorganisms such Thiomonas spp. which could oxidize arsenite to arsenate. Bioremoval of arsenic through the use of jarosite precipitates generated by Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans was also found to be very effective. Biotechnological processes hold great promise in the remediation of acid mine drainage and efficient removal of toxic metal ions such as copper, zinc and arsenic.     

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.)。     

Influence of geometry and solids concentration on the hydrodynamics and mass transfer of a rectangular airlift reactor for marine sediment and soil bioremediation

Hydrodynamics and mass transfer characteristics of a three-phase airlift reactor were studied in a rectangular split-vessel reactor and using an air-seawater-marine sediment system. Experiments were conducted over a range of downcomer to riser cross-sectional area ratios (A_D/A_R = 0.65 to 1.0) for two-phase systems and for five sediment concentrations (5 to 25% w/v) using marine sediments. The influence of higher sediment concentrations (30 to 50% w/v) was examined for A_D/A_R = 1. The presence of fine sediment particles in the system had little effect on hydrodynamic and mass transfer parameters compared to the two-phase systems up to 25% loading, decreasing at higher loadings. The airlift reactor was found to meet the dissolved oxygen demand needed for a contaminated sediment treatment process. Axial distribution of the particles was uniform along the riser and the downcomer. Correlations were developed that described the hydrodynamic and mass transfer behaviour for all experimental conditions examined.     

Evaluation of basidiomycetous fungi for pretreatment of contaminated soil

BACKGROUND: For most dioxin‐contaminated sawmill soils, combustion is recommended. However, the process may be inefficient if the soil has a high organic matter content. The use of saprotrophic basidiomycetous fungi is an alternative for pretreatment of this kind of soil. A total of 147 fungi were evaluated for their ability to grow in sawmill soil. From this screening, the best soil colonizing fungi were selected to study their enzyme activities and degradation of soil organic matter. Pine (Pinus sylvestris) bark was used as a co‐substrate to propagate the fungi into the soil. The activities of manganese peroxidase (MnP), laccase, endo‐1,4‐β‐glucanase, endo‐1,4‐β‐xylanase, and endo‐1,4‐β‐mannanase were analysed from the inocula and fungal treated soil. RESULTS: The screening revealed that 56 out of 147 fungi were able to grow in non‐sterile soil, and most of them were litter‐decomposing fungi (LDF). In pine bark cultures, the highest enzyme activities were observed with Phanerochaete velutina, which produced 5 U g^?1 of MnP. The activity of endo‐1,4‐β‐glucanase was generally higher than that of other hydrolytic enzymes. The highest carbon loss from soil with a high organic matter content was achieved by P. velutina (3.4%) and Stropharia rugosoannulata (2.4%). CONCLUSIONS: Many LDF, and in addition the white‐rot fungus P. velutina, are potential degraders of soil organic matter since they showed good growth and respiratory activity. Pine bark was a suitable lignocellulosic co‐substrate and a good promoter of MnP activity. Copyright © 2009 Society of Chemical Industry     

The effect of three chemical oxidants on subsequent biodegradation of 2,4‐dinitrotoluene (DNT) in batch slurry reactors

BACKGROUND: Recent studies indicate that chemical oxidation may be compatible with subsequent biodegradation in contaminated soils. To test this, soil contaminated with 2,4‐dinintrotoluene (2,4‐DNT) was treated in batch slurry reactors with (1) ozone, (2) modified Fenton chemistry (MFC), and (3) iron‐activated sodium persulfate (SPS). Chemical and subsequent biological oxidation were monitored, and compared with biodegradation alone. Release of nitrite and nitrate distinguished biological from chemical oxidation of 2,4‐DNT, respectively. DNT‐degrading microorganisms were enumerated. The disappearance of volatile fatty acids (VFAs) accumulated during chemical oxidation was also monitored. RESULTS: In the biological reactor 66% of the 2,4‐DNT was degraded, but further biodegradation was inhibited by nitrite concentrations approaching 18 mmol L^?1. At the doses tested, all oxidants achieved chemical oxidation followed by biodegradation, resulting in 98% DNT removal overall. Ozone achieved the greatest DNT removal (70%), but also caused the greatest reduction in DNT degraders and the longest rebound time (60 days) before biodegradation of the remaining DNT and VFAs. SPS resulted in the least DNT removal by chemical oxidation (37%), but showed no obvious rebound period for DNT degraders, and even signs of co‐existing chemical and biological oxidation. By releasing nitrate, which is less toxic than nitrite, the oxidants kept nitrite levels below 18 mmol L^?1, enabling the follow‐on biodegradation step to attain lower concentrations of 2,4‐DNT than biodegradation alone. CONCLUSIONS: All three chemical oxidants were compatible with biodegradation of residual 2,4‐DNT. Post‐oxidation bioremediation should be included in remedial designs. Copyright © 2009 Society of Chemical Industry     

石油污染土壤微生物群落分布特征

采用高通量测序法研究东营某炼油厂不同污染程度的土壤中细菌、真菌和古菌的群落结构,分析石油污染对土壤微生物群落结构的影响。结果表明：微生物群落可操作分类单元(OTU)数量随着油污土壤油含量的增加先增多后减少;Beta多样性与土壤石油污染程度有一定的关系;受污染程度相近的土壤样品,微生物群落结构的相似度较高。细菌、真菌、古菌群落中相对丰度最大的分别为变形菌门(Proteobacteria)、子囊菌门(Ascomycota)和奇古菌门(Thaumarchaeota),分别为44.8%～79.5%、54.4%～83.2%和28.3%～93.1%。属水平群落聚类分析结果显示,随着土壤油含量增加,真菌踝节菌属(Talaromyces)的相对丰度由0增加到31.6%,细菌寡养单胞菌(Stenotrophomonas)由0.1%增加到1.9%,古菌甲烷八叠球菌属(Methanosarcina)由5.8%增加到37.8%。微生物群落结构与土壤中烃类组分含量相关性分析发现,真菌炭疽菌属(Colletotrichum)、细菌节杆菌属(Arthrobacter)、古菌盐红菌属(Halorubrum)与烷烃含量呈显著正相关性,细菌甲基杆菌属(Methylobacterium)、古菌甲烷八叠球菌属(Methanosarcina)与芳香烃含量呈显著正相关性。