生物过滤塔降解BTEX行为的研究

以陶粒为填料,对生物过滤塔降解BTEX的行为进行了研究。结果表明,在不同氮源浓度条件下,4种物质的生物降解程度不同,生物降解最优的氮源浓度为2.0 g.L-1,而且也表明苯系物中碳原子数与生物降解程度的关系。通过对BTEX生物降解反应平衡方程的分析,得出有机物体积去除负荷与降解过程所产生的CO2之间基本上存在线性关系,并得出了线性回归方程。通过试验数据对反应平衡方程的各系数进行了计算,结果表明Pc/Lr近似为一常数,Pc/Lr的试验值与挥发性有机物完全氧化(不考虑生物量产生)时的计算值相比要小。比较4种挥发性有机物的生物降解反应平衡方程的系数可以看出,BTEX的反应路径相似。     

Method Dependency in the Measurement of BTEX Levels in Contaminated Soil

Environmental consultants and analytical laboratories are increasingly realizing the importance of analytical method selection and validation for the reliable measurement of soil contamination. Aromatic hydrocarbons (BTEX) is one class of environmentally significant soil contamination for which testing is required by regulatory authorities in most industrialized countries. Unfortunately, in most guidelines there is a lack of direction for the selection of a testing method for BTEX and, in practice, any one of a variety of methods may be employed. The fact that these may not all yield comparable results is a source of much frustration in the industry and there is a paucity of published research into this problem. In a number of carefully controlled experiments, the method dependency of measured BTEX levels in contaminated soil samples has been investigated. Three commonly employed methods, namely, (methanol extraction) purge-and-trap/gas chromatography with mass selective detection (P&T/GCMSD), headspace/GCMSD and dichloromethane (DCM) extraction/gas chromatography with flame ionization detection (GCFID) have been compared in the analysis of 109 gasoline-contaminated soil samples collected from station sites in Melbourne, Australia. Measurable BTEX concentrations were recorded in 92% of the samples using P&T/GCMSD, 59% using DCM/GCFID, and 40% using headspace/GCMSD. Correspondingly, the magnitudes of the recovered concentrations were significantly higher by P&T/GCMSD than by DCM/GCFID, which in turn were significantly higher than the magnitudes determined by headspace/GCMSD. These trends are evident for both clay and sandy soils. These studies clearly demonstrate that, for the three commonly employed methods described, measured BTEX levels are extraction and analytical method dependent in at least two different soil types.     

Spatial Changes of Redox Environment in Aquifer Contaminated by BTEX

The changes of redox environment conditions and the concentrations of BTEX in different conditions are monitored in this study through setting simulated column. The results showed that the concentration of redox components presented zoning in the simulated column. Oxygen reduction zone formatted in 80～98 cm away from the source, Nitrate reduction zone formatted in 60～80 cm, Iron reduction zone formatted in 35～60 cm, and Sulfate reduction zone formatted in 30～50 cm. At the bottom of the column, the methane zone formatted in 0～30 cm because of the decreasing of HCO3-. The concentration of BTEX components showed a sharp decline. The degradation rates of benzene, toluene, ethylbenzene, xylene and o-xylene reached 99.94%, 99.96%, 99.94%, 99.49% and 98.3%, respectively.     

顶空-气质联用法分析水基胶中的苯系物

[目的]测定水基胶中的苯系物。[方法]分别对不同的前处理方法、溶剂、顶空平衡时间和平衡温度进行比较选择,并采用气质联用法/SIM测定水基胶中的苯、甲苯、乙苯、邻二甲苯、间二甲苯、对二甲苯。[结果]N,N-二甲基甲酰胺为最佳溶剂,顶空条件为最佳前处理手段,且其最佳平衡温度80℃,最佳平衡时间15 min;该方法的回收率为96.96%～105.19%,RSD为1.082%～2.082%,定量限为0.003～0.016 mg/kg。[结论]顶空-气质联用法前处理简单、污染小,方法简单、快速,具有较高的灵敏度和准确度,测定结果准确、可靠。     

BTEX厌氧降解纯菌株的筛选及降解效率影响因素研究

通过驯化和分离纯化方法,从被污染的土壤中筛选出3株厌氧降解BTEX的纯菌种,对地下水中苯系物(BTEX)在厌氧条件下的微生物降解进行研究.采用正交试验法对BTEX各个组分在不同菌种、不同电子受体和污染物不同起始浓度的条件下生物厌氧降解效率进行研究.结果表明,苯、甲苯和乙苯在以硝酸根和硫酸根为电子受体、污染物初始浓度较低的条件下,降解效率可达95%,而以3价铁为电子受体或者初始浓度较高时降解效率较低.二甲苯在各种条件下都可以得到有效的降解.在各个因素中,电子受体对BTEX降解效率的影响最大.     

Rhizosphere effect of Galega orientalis in oil-contaminated soil

Randomized lysimeters in an oil-contaminated field contained the following treatments: (1) Galega orientalis seeds inoculated with Rhizobium galegae HAMBI 540, (2) bioaugmentation with Pseudomonas putida PaW85, and (3) R. galegae -inoculated G. orientalis seeds plus bioaugmentation with P. putida PaW85. The bacterial abundance and diversity were analysed in composite samples after one growing season. A total of 208 m-toluate tolerating bacteria were isolated and screened with m-toluate tolerance and utilization tests, and the catechol test. Seventy-nine isolates were characterized with (GTG)₅-PCR genomic fingerprinting and 16S rRNA gene PCR-RFLP ribotyping. Only 10% of the isolated strains were able to degrade m-toluate. Most of the m-toluate utilizing bacteria were catechol positive indicating the existence of a TOL plasmid. Rhizosphere effect of G. orientalis was manifested in oil-contaminated soil. G. orientalis and Pseudomonas bioaugmentation increased the amount of bacteria in oil-contaminated soil. G. orientalis especially together with Pseudomonas bioaugmentation increased the numbers of m-toluate utilizing and catechol positive bacteria in the soil samples indicating an increase in degradation potential. The rhizosphere of G. orientalis increased also the diversity of bacteria. More ribotypes were found in soils treated with G. orientalis and P. putida PaW85 compared to the untreated soil, but the diversity of the m-toluate utilizing bacteria did not significantly increase.     

污水河地区地下水土中苯系物分布特征分析——以太行山前平原为例

通过对河水、河床底泥、岸边土壤剖面、地下水样品的测定,对太行山前平原磁河地区地下水中苯系物在水土系统中的分布特征进行了研究。结果表明,各种介质中的苯系物(苯、甲苯、乙苯、二甲苯)具有一定的相关性,与河不同距离和不同深度土壤中的苯系污染物主要来自污水河。但是,由于有机污染物在土壤中的吸附等作用过程,有机污染物浓度在一定的距离内迅速降低。在河岸边不同距离的地下水中,仅少量地下水水样中检出了苯系物,但它们的浓度均低于生活饮用水的要求限值。     

河流渗滤系统中BTEX的吸附行为实验模拟研究

河流渗滤是一种自然净化过程,污染河水通过该过程在河流沉积层中发生物理、化学和生物作用,使得污染物浓度降低,入渗河水水质得到净化。为了研究BTEX污染河水通过河流渗滤系统时的吸附行为,进行了静态吸附模拟实验。结果表明BTEX4种组分在3种河流沉积物样品中的吸附平衡均可以在48h内完成。通过比较BTEX在3种不同河流沉积物样品中的吸附动力学曲线,可以发现BTEX在粉土中吸附速率最大,细砂中次之,粗砂中最小。BTEX在粉土和细砂中的吸附等温线符合Henry等温吸附方程,而在粗砂中符合Langmuir等温吸附方程。3种土壤中粉土和细砂具有较大的吸附容量,而粗砂吸附容量相对较小;粉土和细砂对苯的吸附能力最强,甲苯次之,乙苯和间二甲苯相对较小。从阻滞因子的计算结果来看,黄河花园口区采集的河流沉积物样品对BTEX各组分的迁移均具有较强的阻滞作用,在较高浓度范围内,河流渗滤系统能够通过吸附作用有效阻滞BTEX污染物,降低其对地下水的危害。     

蒸汽强化气相抽提修复苯系物污染粘性土壤

蒸汽强化土壤气相抽提是近期发展并具良好应用前景的土壤污染修复技术。研究以6种挥发性苯系物(BTEX)为目标污染物,考察了抽气速率、搅拌速率、土壤温度、蒸汽加热功率等对土壤污染物去除的影响及抽提过程特征。结果表明,调质药剂(0~40%)、搅拌速率(60~300r/min)、土壤温度(60~150℃)和加热功率(100~400 W)对污染物的去除影响较大,而抽气速率(3.0~15.0L/min)影响较小。较佳的工艺条件为:抽气速率6.0L/min、调质药剂40%、搅拌速率300r/min、土壤温度100℃和加热功率200 W。此条件下土壤气相苯系物浓度遵从一级衰减动力学模型,其速率常数与污染物沸点呈负相关;伴随冷凝水中污染物浓度逐渐下降,6d后土壤有机质含量从初始6.998%下降至2.741%,污染物整体去除率均超90%。研究表明,该技术是BTEX污染粘性土壤的一种快速、有效的修复方法。     

过硫酸盐活化技术处理地下水中的BTEX及其动力学

利用模拟苯、甲苯、乙苯和二甲苯(BTEX)污染的地下水,研究过硫酸盐(Na2S2O8)活化氧化处理BTEX污染。结果表明,过硫酸盐对BTEX污染的地下水具有很好的处理能力。当Na2S2O8/BTEX(摩尔比)=20,Na2S2O8/Fe2+(摩尔比)=8的时候,BTEX的处理效果最好,甲苯、乙苯和二甲苯去除率均能达到80%以上;而苯的去除率稍低。整个试验过程中体系均处于强氧化环境,pH值降至3以下。过硫酸盐对苯、甲苯、乙苯和二甲苯(BTEX)的去除过程均符合二级反应动力学:1/ct=kt+1/c0。