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A regression curve based on a Weibull distribution model is generated to describe the binodal curve on a three component liquid-liquid ternary phase diagram. The methodology involves transforming the experimental phase partitioning data points of each mixture from the ternary phase diagram to equivalent Cartesian coordinates. The regression curve is then generated, and the regression curve becomes the Weibull-derived binodal curve by superimposing the regression curve onto the original ternary phase diagram. A total of seven regression curves for seven ternary mixtures are generated in this study. From the regression analysis, the resulting [R.sup.2] value for each mixture is very close to one, indicating that there is strong correlation between the regression curve and the transformed experimental data points. The method developed in this research allows researchers to empirically describe a binodal curve, which is useful in analyzing and predicting the various phase partitioning scenarios of a three-component liquid-liquid system. DOI: 10.1061/(ASCE)EE.1943-7870.0000196 CE Database subject headings: Groundwater pollution; Equilibrium; Regression models; Nonaqueous phase liquids. Author keywords: Groundwater pollution; Nonaqueous phase liquid; Equilibrium; Regression models.

Laboratory experiments are conducted to determine the liquid-liquid phase separation behavior of six three-component systems with each system comprised of a common alcohol (namely ethanol, isopropanol, or methanol), water, and one of two engineered dense nonaqueous phase liquids (DNAPLs) manufactured by the 3[M.sup.TM] Corporation (namely methoxy-nonafluorobutane (HFE-7100) or ethoxy-nonafluorobutane (HFE-200)). The experimental results are presented on ternary phase diagrams and compared against available published experimental data where tetrachloroethylene (PCE) and (or) trichloroethylene (TCE) is the dense nonaqueous phase liquid (DNAPL). Results show that the two engineered fluids exhibit similar phase separation behavior in the presence of the same alcohol. Furthermore, these engineered fluids exhibit similar phase separation behavior to that of PCE, but relatively dissimilar phase separation behavior to that of TCE. Key words: alcohol, HFE-7100, HFE-7200, nonaqueous phase liquids, liquid-liquid phase separation, PCE, TCE. Des experiences de laboratoire ont ete realisees pour determiner le comportement de separation en phase liquide-liquide de six systemes a trois composantes; chaque systeme comportait un alcool commun (ethanol, alcool isopro-pylique on methanol), de l'eau et un des deux liquides non aqueux denses artificiels fabriques par 3MMc (methoxy-nonafluorobutane (HFE-7100) on ethoxy-nonafluorobutane (HFE-7200)). Les resultats experimentaux sont presentes sur des diagrammes de phases ternaires et compares aux donnees experimentales publiees dans lesquelles le liquide non aqueux dense artificiel etait le tetrachlorethylene (PCE) et(ou) le trichlorethylene (TCE). Les resultats montrent que les deux liquides artificiels montraient une separation de phase similaire en presence d'un alcool donne. De plus, ces liquides artificiels presentaient une separation de phase similaire a celle du PCE, mais relativement differente de celle du TCE. Mots-cles : alcool, HFE-7100, HFE-7200, liquides non aqueux, separation en phase liquide-liquide, PCE, TCE. [Traduit par la Redaction], Introduction Subsurface contamination from dense nonaqueous phase liquids (DNAPLs, with specific gravity greater than 1) such as tetrachloroethylene (PCE) or trichloroethylene (TCE) is a widespread problem. As a response, environmental [...]

A novel pilot-scale photochemical reactor is utilized to carry out vapor-phase tetrachloroethylene (PCE) and trichloroethylene (TCE) destruction experiments from the exhaust of a groundwater remediation air stripper. The cylindrical-shaped stainless steel photochemical reactor has an inner diameter of 32 cm and a length of 105 cm. Low-pressure mercury ultraviolet (UV) lamps are used as the photochemical energy source to initiate the destruction reaction within the reactor. A cylindrical-shaped air stripper with a volume of 15.7 L is constructed and utilized for transferring the contaminant from the aqueous phase to the vapor phase. Experiments are conducted using the air stripper to determine phase-transfer characteristics of PCE and TCE. The results show good contaminant phase transfer using clean airflow rates of 1.5 and 3.0 L/min. Next, groundwater remediation experiments are conducted with the air stripper exhaust flowing into the photochemical reactor for contaminant destruction. The first experiment use distilled water contaminated with dissolved PCE, the second experiment use distilled water contaminated with dissolved TCE, and the third experiment use distilled water contaminated With both dissolved PCE and TCE. All three experiments show excellent contaminant destruction efficiencies. This study demonstrates that the photochemical reactor should be included as part of an overall air-stripping PCE/TCE groundwater remediation scheme for complete contaminant destruction. DOI: 10.1061/(ASCE)0733-9372(2005)131:10(1441) CE Database subject headings: Ground-water pollution; Reactors; Air stripping; PCE; TCE; Ultraviolet radiation.

In this study, a three-dimensional mathematical model for simulating the transport of dissolved contaminants originating from an elliptic-shaped coal tar pool in homogeneous saturated porous media is developed. The methodology of the solution is based on a semianalytical approach that assumes the contaminant source input can be represented by the superposition of a series of consecutive short dissolution pulses, The model accounts for possible solidification of polycyclic aromatic hydrocarbon compounds as the coal tar pool dissolves. A circular-shaped synthetic coal tar pool consisting of 22 components is used for model simulation. Simulations show that even after 130 years of dissolution, the coal tar pool remains a potential groundwater pollution threat despite a significant reduction in overall pool volume. DOI: 10.1061/(ASCE)0733-9372(2004)130:12(1507) CE Database subject headings: Coal tar; Ground-water pollution; Mathematical models; Nonaqueous phase liquids; Porous materials; Hydrologic models.

In this study, an existing thermodynamic model was used to predict equilibrium phase partitioning behavior of a cosolvent in a two-phase nonaqueous phase liquid (NAPL)-water system. The activity coefficients are calculated using the universal quasichemical functional group activity coefficient (UNIFAC) method. We examined an assortment of cosolvent-NAPL pairs of environmental interest and compared the UNIFAC-predicted ternary phase diagrams against published experimentally derived ternary phase diagrams. Results show that the UNIFAC model is a promising method for predicting equilibrium cosolvent partitioning behavior in NAPL water systems, and thus can be useful in estimating the potential for NAPL solubilization and mobilization in remediation processes. The cosolvent partitioning behavior is interpreted with regard to changes in the physical properties of the NAPL-water system. Changes in interfacial tension between the two phases were estimated using an existing correlation. A viscosity experiment was conducted for selected mixtures of ethanol, toluene, and water; and the viscosity was found to increase with increasing amounts of the cosolvent. CE Database subject headings: Thermodynamics; Ground-water pollution; Viscosity; Remedial action; Nonaqueous phase liquids.

A custom designed pilot-scale photochemical remediation reactor is constructed for remediation of vapor-phase volatile organic halocarbons (VOHs), particularly chlorinated hydrocarbons such as PCE (tetrachloroethylene). Ultraviolet (UV) light, when emitted at an effective absorption frequency, cleaves a VOH's carbon-chloride bond, transforming harmful contaminants to harmless products. The stainless steel reactor is of tubular-shape with an inner diameter of 32 cm and a length of 105 cm. The net volume of the reactor is approximately 73.7 L. Three stainless steel baffles are welded inside the reactor to create a well-mixed vapor phase and uniform UV contact time. Special low-pressure mercury amalgam UV lamps (Heraeus, Inc., Duluth, Ga.) are used as the photoenergy source. Two independent vapor-phase PCE destruction experiments are conducted using different influent contaminant concentrations. Both experiments show a PCE destruction efficiency of over 99%. CE Database subject headings: Photochemical reactions; Cisterns; PCE; Design; Construction.

A two-dimensional numerical model is developed to study contaminant transport resulting from the dissolution of single- and multicomponent dense nonaqueous-phase liquid (DNAPL) pools in heterogeneous porous media. The aqueous-phase concentration of each dissolved component is assumed to undergo first-order decay as well as sorb under local equilibrium conditions. Pool shrinkage is accounted for by modeling the progressive reduction of the DNAPL pool surface area as a time-dependent boundary. Multicomponent pool dissolution is modeled using an effective solubility (or equilibrium aqueous solubility) relationship, where the nonaqueous-phase activity coefficient for each constituent is evaluated at each and every time step. Subsurface heterogeneities are depicted by an ideally stratified porous formation and by a statistically anisotropic aquifer. In the stratified formation, a multicomponent DNAPL pool is assumed to be formed at the interface between a sand layer and a clay layer, where DNAPL dissolution occurs simultaneously in both strata. The ground-water velocity inside the sand stratum is uniform in the longitudinal direction whereas the interstitial liquid in the aquitard is stagnant. In the statistically anisotropic aquifer, a single-component DNAPL pool is assumed to be formed on top of an impermeable bedrock, where DNAPL dissolution occurs in the aquifer only. Results from several model simulations indicate that dissolved contaminant concentrations in aquifers are reduced significantly in the presence of aquitards, and most importantly, the transfer of dissolved contaminants along the pool-water interface is slower within statistically anisotropic than within homogeneous aquifers.

The article discusses several aspects of nonpoint sources (NPS) pollution, including general policy and attitudes; water quality of water resources; best management practices (BMPs) for NPS control; NPS modeling and monitoring; and use of Geographic information systems (GIS) for NPS applications.

Patellar and hamstring tendinopathy are common injuries among elite athletes. Platelet-rich plasma (PRP) has emerged as a promising new therapy for accelerating healing and shortening recovery in patients with these conditions. We present 15 cases of PRP injection used for either patellar or hamstring tendinopathy in varsity collegiate athletes at a single institution. All of the athletes in our case series with hamstring or patellar tendinopathy were fully able to return to sport. Three of the athletes with patellar tendinopathy were referred for surgery, while none of the athletes with hamstring strain underwent a subsequent surgical procedure., (© 2019 Published by Elsevier B.V. on behalf of Professor P K Surendran Memorial Education Foundation.)