Predicting DNAPL entrapment and recovery: the influence of hydraulic property correlation

The influence of aquifer property correlation on multiphase fluid migration, entrapment and recovery was explored by incorporating correlated and uncorrelated porosity, permeability, and capillary pressure-saturation (P_c-Sat) parameter fields in a cross-sectional numerical multiphase flow model. Comparison of two-dimensional entrapped organic saturation distributions for a simulated tetrachloroethylene (PCE) spill in ensembles of aquifer realizations suggests that the degree of spatial correlation in P_c-Sat parameters exerts a controlling influence on dense nonaqueous phase liquid (DNAPL) spreading and redistribution in saturated aquifers. The predicted evolution of DNAPL source zones and resultant remediation efficiency under surfactant enhanced aquifer remediation (SEAR) also appear to be strongly influenced by the spatial correlation of aquifer parameters and multiphase flow constitutive relationships. Results for a limited number of realizations selected from each ensemble showed that removal of 60% to 99% of entrapped PCE could reduce dissolved contaminant concentration and mass flux by approximately two orders of magnitude under natural gradient conditions. Aqueous phase contaminant mass flux did not vary uniformly as a function of % DNAPL removed, however, and notable differences in behavior were observed for models incorporating correlated versus uncorrelated P_c-Sat and permeability fields. Although these results must be confirmed through analysis of additional realizations, it is likely that similar or larger differences between correlated and uncorrelated system behavior will be observed in aquifers with greater spatially variability than that of the nonuniform, homogeneous sand aquifer studied here. Funding for this research was provided by the United States Environmental Protection Agency, Great Lakes and Mid-Atlantic Center for Hazardous Substance Research under Grant No. R-825540, the Michigan Department of Environmental Quality under Contract No. Y80011, and the Strategic Environmental Research and Development Program under Project No. CU-1293. The content of this publication does not necessarily represent the views of these agencies and has not been subject to agency review.     

Electrokinetic Removal of Petroleum Hydrocarbon from Residual Clayey Soil Following a Washing Process

This study investigates total petroleum hydrocarbon (TPH) removal from residual clayey soil, after a washing procedure, using an electrokinetic process. Eight electrokinetic experiments were carried out to investigate the characteristics of TPH removal. When 0.1 M MgSO₄ or 0.1 M NaOH was used as an electrolyte, the electric current rapidly increased within the first 100 or 200 h, respectively. A negatively charged soil surface resulted in a more negative zeta potential and greater electroosmotic flow toward the cathode. Therefore, the accumulated electroosmotic flow (EOF) when using 0.1 M NaOH as the anolyte‐purging solution was higher than when using 0.1 M MgSO₄. Although the energy consumption for the two purging solutions was similar, the efficiencies of TPH removal when 0.1 M MgSO₄ and 0.1 M NaOH with surfactant were used were 0 and 39%, respectively, because the electroosmotic flow rate increased with TPH removal efficiency. When 5% isopropyl alcohol (IPA) was used as a circulation solution, the electric current increased but the TPH removal was similar to that using water. In terms of energy consumption, the use of a surfactant‐enhanced electrokinetic process with NaOH as electrolyte was effective in removing TPHs from low‐permeability soil.     

Bioremediation of Phenanthrene by Mycoplana sp. MVMB2 Isolated from Contaminated Soil

The effect of nutrient and surfactant addition on the biodegradation of phenanthrene was studied in a batch scale soil–slurry system using isolated Mycoplana sp. MVMB2strain. The study was conducted using an artificially phenanthrene spiked and as well as contaminated soil from petrochemical industrial site. Maximum phenanthrene degradation and subsequent high microbial growth were observed at optimum pH (pH 6) and C/N/P ratio (100:20:3). To investigate maximum substrate degradation potential of Mycoplana sp. MVMB2, very high concentrations of phenanthrene (50–200 mg/kg soil) were used. The organism was capable of degrading >60% for a concentration below 20 mg/kg soil and >40% for concentrations up to 200 mg/kg within 8 days. Further the influence of five different surfactants namely Span 80, Tween 20, Triton X‐100, cetyl trimethyl ammonium bromide, and sodium dodecyl sulfate were tested at their critical micelle concentration (CMC) levels for phenanthrene degradation in the soil. The addition of surfactant enhanced the biodegradation and a maximum of 84.49% was obtained for Triton X‐100. Complete phenanthrene degradation by Mycoplana sp. MVMB2 was observed at 3 CMC concentration of Triton X‐100. The optimized parameters obtained were used for the degradation of phenanthrene present in the contaminated soil and 98.6% biodegradation was obtained. Thus, the results obtained in the study suggested that biodegradation of phenanthrene by Mycoplana sp. MVMB2 appeared to be feasible to remediate phenanthrene rich contaminated sites.     

Sorption-desorption kinetics and toxic cell concentration in marine phytoplankton microalgae exposed to Linear Alkylbenzene Sulfonate

Linear Alkylbenzene Sulfonates (LAS) are ubiquitous surfactants. Traces can be found in coastal environments. Sorption and toxicity of C₁₂-LAS congeners were studied in controlled conditions (2-3500 μg C₁₂LAS/L) in five marine phytoplanktonic species, using standardized methods. IC₅₀ values ranged from 0.5 to 2 mg LAS/L. Sorption of ¹⁴C₁₂-6 LAS isomer was measured at environmentally relevant trace levels (4 μg/L) using liquid scintillation counting. Steady-state sorption on algae was reached within 5 h in the order dinoflagellate > diatoms > green algae. The sorption data, fitted a L-type Freundlich isotherm, indicating saturation. Desorption was rapid but a low LAS fraction was still sorbed after 24 h. Toxic cell concentration was 0.38 ± 0.09 mg/g for the studied species. LAS toxicity results from sorption on biological membranes leading to non-specific disturbance of algal growth. Results indicate that LAS concentrations in coastal environments do not represent a risk for these organisms.     

Surfactant Enhance DLLME/FO‐LADS: Assay of Malachite Green Level in Aquatic Environment of Trout Fish

Malachite green (MG), a traditional agent used in aquaculture although is not approved; its low cost and high efficacy make illicit use likely. We developed a small‐scale, simple, and sensitive dispersive liquid–liquid microextraction procedure for the assay of trace amounts of MG in aquatic environment of Trout fish. Fiber optic‐linear array detection spectrophotometry with charge‐coupled device detector benefiting from a microcell was used for this purpose. The method is based on enhancement effect of an anionic surfactant on the extraction of MG in to very fine multidroplets of microextraction solvent which made assisted by disperser solvent. Under the optimum conditions, the enrichment factor 77.5 was obtained from a 5‐mL water sample. The calibration graph was linear up to 5 × 10^?7 mol L^?1 with detection limit of 1 × 10^?8 mol L^?1. The relative standard deviation for seven replicate measurements of 4 × 10^?7 and 5 × 10^?8 mol L^?1 of MG were 3.3 and 4.5%, respectively.     

硫酸钾镁肥防结块剂的开发研究

分析了青海中信国安科技发展有限公司生产的"国安"牌硫酸钾镁肥产品在生产和运输中产生的结块现象,针对硫酸钾镁肥产品产生结块的原因,开发研制了一种主要成分为阴离子表面活性剂(分子的活性部分有一个带负电荷的离子如磺酸盐、烷基芳基磺酸盐、烷基磺酸盐和脂肪酸铵盐等)的防结块剂产品。     

Mobilisierbarkeit von hydrophoben organischen Schadstoffen in belasteten Böden und Abfällen. Teil I: Mobilisierbarkeit von PCB,PAK und n-Alkanen durch Lösungsvermittler

Mobilization Potential of Hydrophobic Organic Compounds (HOCs) in Contaminated Soils and Waste Materials. Part I: Mobilization Potential of PCBs, PAHs, and Aliphatic Hydrocarbons in the Presence of Solubilizing Substances When using an elution procedure for organic pollutants to estimate the leaching behaviour of contamined soils and waste deposits, the influence of organic matter in solids and eluates adequately has to be considered. In batch tests with a solid/liquid ratio of 1:10, various aqueous solutions were composed, the solubilizing effect of which can be attributed to ubiquitous natural compounds (e. g., phospholipids, humic and carbonic acids). These solutions were evaluated in regard to the mobilization of PAHs, PCBs, and aliphatic hydrocarbons in soil and waste samples. The results were compared with batch tests containing sodium dodecyl sulfate (SDS), the properties and applications of which are selected and optimized in order to simulate the chemical interactions between pollutant and solubilizing substances of natural sources. Under alkaline conditions, the part of eluated pollutants was high because of the release of humic substances indigenous to the sample. Low concentrations of phospholipids and humic acid could decrease the mobility of aliphatic hydrocarbons. The extend of HOC mobilization is affected by specific interdependences between solubilizing substances and reactive matter of the samples. For most samples, 5.0 g/L concentrated SDS solution was able to simulate the most effective natural solutizer potential in regard to the mobilization of PAHs, PCBs, and aliphatic hydrocarbons within the system of batch tests. Whereas elution with pure water caused significant deviations in pollutant composition and too low yields, the use of SDS effected à good conformity. Modified in such a manner, the elution procedure can follow DIN 38414 part 4, when loss of pollutants will be minimized; e. g., centrifugation is needed to separate phases.     

正己烷/海水微乳液形成的相图研究

用相图方法研究正己烷／海水微乳液的形成。体系相图由水（或人工海水，盐度分别为０，１３．６９６，３０．０７０和４１．１１８）／油（正己烷）／表面活性剂（ＡＳ，ＣＴＡＢ及ＢＲＩＪ３５）／助表面活性剂（正丁醇）在４０℃时构成。分别研究表面活性剂类型，油及醇含量和海水盐度对微乳液形成的影响。结果表明：醇与表面活性剂的摩尔浓度比值大于１时，最适宜于形成微乳液；形成微乳液区的面积随正己烷含量增加而减少；含离子     

钍-水扬基荧光酮-两性及非离子表面活性剂胶束增溶络合物光度法的研究及其在岩石分析中的应用

本文提出用水扬基荧光酮(SF)和十二烷基二甲基铵基乙酸(DDMAA)及非离子表面活性剂(Triton X-100)测定岩石中钍的灵敏的分光光度法,在ρH=9.4—10的NH_4Ac-NH_4OH介质中,钍生成玫瑰色胶束增溶络合物。此络合物在567nm处具有最大吸收,摩尔吸光系数ε=1.74×10~5,在DDMAA和Triton X-100存在条件下,络合物组成为Th:SF=1:2,钍浓度至少在0—30μg/25ml范围内服从比耳定律。经743大孔强酸型阳离子交换树脂分离后,岩石中一般干扰元素不影响钍的测定。     

Effects of surfactants and electrolyte solutions on the properties of soil

Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction, strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO₃ decreased the liquid limit and plasticity index of the test soil. Maximum dry unit weights were increased and optimum moisture contents were decreased as SDS and biosurfactant were added for the compaction tests for mixtures of 30% kaolinite and 70% sand. The addition of non-ionic surfactant, biosurfactant, and CaCl₂ increased the initial elastic modulus and undrained shear strength of the kaolinite–sand mixture soils. Hydraulic conductivities were measured by fixed-wall double-ring permeameters. Results showed that the hydraulic conductivity was not significantly affected, but slightly decreased from 1×10⁻⁷ cm/s (water) to 0.3×10⁻⁷ cm/s for Triton X-100 and SDS. The adsorption characteristics of the chemicals onto kaolinite were also investigated by developing isotherm curves. SDS adsorbed onto soil particles with the strongest bonding strength of the fluids tested. Correlations among parameters were developed for surfactants, electrolyte solutions, and clayey soils.