Combination of steam-enhanced extraction and electrical resistance heating for efficient remediation of perchloroethylene-contaminated soil: Coupling merits and energy consumption

● Coupling merits of SEE and ERH were explored by a laboratory-scale device. ● SEE promotes the soil electrical conductivity and ERH process. ● Preheating soil by ERH improves the soil permeability and SEE. ● Combined method is more energy-efficient for perchloroethylene extraction. In situ thermal desorption (ISTD) technology effectively remediates soil contaminated by dense nonaqueous phase liquids (DNAPLs). However, more efforts are required to minimize the energy consumption of ISTD technology. This study developed a laboratory-scale experimental device to explore the coupling merits of two traditional desorption technologies: steam-enhanced extraction (SEE) and electrical resistance heating (ERH). The results showed that injecting high-density steam (> 1 g/min) into loam or clay with relatively high moisture content (> 13.3%) could fracture the soil matrix and lead to the occurrence of the preferential flow of steam. For ERH alone, the electrical resistance and soil moisture loss were critical factors influencing heating power. When ERH and SEE were combined, preheating soil by ERH could increase soil permeability, effectively alleviating the problem of preferential flow of SEE. Meanwhile, steam injection heated the soil and provided moisture for maintaining soil electrical conductivity, thereby ensuring power stability in the ERH process. Compared with ERH alone (8 V/cm) and SEE alone (1 g/min steam), the energy consumption of combined method in remediating perchloroethylene-contaminated soil was reduced by 39.3% and 52.9%, respectively. These findings indicate that the combined method is more favorable than ERH or SEE alone for remediating DNAPL-contaminated subsurfaces when considering ISTD technology.     

环境样品中DNA提取方法的研究进展

利用微生物降解污染物是废水处理中的常用方法,研究废水处理工艺中微生物的多样性和动态性对于优化废水处理工艺的性能、提高其处理效率具有重要的指导意义.分子生物学方法是研究微生物多样性和动态性的有效方法.由于大多数分子生物学方法都是以提取研究对象的基因组DNA为前提,因此建立一种高效的环境样品DNA的提取方法具有重要作用.综述了从环境样品中提取DNA的主要方法及其研究进展,并提出了一种有效的从活性污泥中提取DNA的具体方法.     

水中痕量多环芳烃(PAHs)类环境污染物检测方法的研究

对水中多环芳烃（ＰＡＨｓ）检测方法进行了系统研究,采用固相萃取技术进行样品前处理,以取代传统的液液萃取,并建立了优化的ＰＡＨｓ液相色谱分析条件,可以适用于美国ＥＰＡ优先监控的水中１６种ＰＡＨｓ的同时分析     

ISS-2锌渣标准样品中Zn、Pb、Cd全量浸取研究及与纯水浸提比较

锌渣标准样品２００目,已经过多家实验室协作定值,通过二种方法可提取样品中的全量Ｐｂ、Ｚｎ、Ｃｄ：（１）１＋９ＨＣｌ,密封,０１２～０１４ＭＰａ,１２１℃,６０ｍｉｎ;（２）１＋９ＨＣｌ,超声波处理,６０ｍｉｎ。     

直接进水样气相色谱法及萃取法测定水中苯系物的比较研究

对二硫化碳萃取法和直接进水样气相色谱法测定水中的苯系物作了分析、比较和研究。对方法进行了线性、精密度等试验,表明了萃取法可以满足对地面水中苯系物的测定要求,直接进水样法则适用于工业废水中苯系物的监测。     

Determination of polycyclic aromatic hydrocarbonswith supercritical fluid extractionand chromatography (SFE/SFC )

Ｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｐｏｌｙｃｙｃｌｉｃａｒｏｍａｔｉｃｈｙｄｒｏｃａｒｂｏｎｓｗｉｔｈｓｕｐｅｒｃｒｉｔｉｃａｌｆｌｕｉｄｅｘｔｒａｃｔｉｏｎａｎｄｃｈｒｏｍａｔｏｇｒａｐｈｙ（ＳＦＥ／ＳＦＣ）ＹａｏＷｅｉｘｉ（ＲｅｓｅａｒｃｈＣｅｎｔｅ...     

煤矸石中Al_2O_3的提取与测定

本文对煤矸石中Ａｌ２Ｏ３的提取与测定方法作了初步研究，对影响Ａｌ２Ｏ３提取率的一些因素进行了实验分析。     

萃取--反萃取分离原子吸收光谱法测定海水痕量的铜锌铅镉

海水中的铜锌铅镉经氯仿乙酸丁脂萃取和硝酸反萃取得到与基体同时分离，用原子吸收光谱法分别测定反萃取液中的这四种金属。该法具有较低的检出限和较好的回收率，对海水测定可获较满意的结果。     

炼钢厂炼焦车间土壤中PAHs的超临界流体萃取-色质联用分析方法研究

超临界流体萃取炼钢厂炼焦车间土壤中多环芳烃的最佳萃取条件为４０ＭＰａ，８０℃，０．５％甲醇动态改性液体ＣＯ２１０ｍＬ时，对土样进行超临界流体萃取，色质联用分析，并与索氏萃取法进行比较。土样中能准确定性的多环芳烃４４种，其中能定量分析的３１种。色谱定量的回收率均值为７８．５％￣１０４．１％，相对标准偏差为５．０％￣１５．６％。     

土壤中持久性有机污染物的提取技术研究

文章介绍了持久性有机污染物的分析检测方法,指明了研究土壤中持久性有机污染物的必要性.将国内最常用的两种提取方法--索式提取和超声波提取进行比较,结果表明了索式提取的方法更适合从土壤中提取多种持久性有机污染物,提取剂和洗脱剂可选比例1:1的丙酮和石油醚,回收率可在70%～90%之间;而超声波提取的方法比较适合从土壤中提取个别的持久性有机污染物,如op′-DDT 和pp′-DDT,节省实验时间,试剂使用量少,回收率也可在50%以上.