http://deepblue.lib.umich.edu/bitstream/handle/2027.42/31591/0000520.pdf?sequence=1

Surfactant enhanced remediation of soil columns contaminated by residual tetrachloroethylene

Biosurfactant-enhanced removal of residual hydrocarbon from soil

The bioremediation of soil contaminated with polycyclic aromatic hydrocarbons (PAH) often is limited by a low bioavailability of the contaminants. The effect of two nonionic surfactants of the alkylphenolethoxylate type, Arkopal N-300 and Sapogenat T-300, on bioavailability of PAH in manufactured gas plant soil was evaluated in soil columns percolated by recirculating flushing water. Both surfactants enhanced the mass transfer rate of sorbed PAH into the aqueous phase due to solubilization. Solubilized PAH were available for biodegradation. Degradation of the surfactants themselves was monitored by counting cell numbers of surfactant degraders. It could be demonstrated that the rapid degradation of Arkopal N-300 resulted in a lack of oxygen and an inhibition of PAH degradation. Sapogenat T-300 was degraded more slowly, but a depletion of oxygen occurred after 54 d of incubation. Until then the surfactant-enhanced PAH mobilization resulted in an increased PAH degradation as compared to the treatment withou...

Surfactant-Enhanced Mobilization and Biodegradation of Polycyclic Aromatic Hydrocarbons in Manufactured Gas Plant Soil

Use of Organoclays in Pollution Abatement

Biodegradable natural surfactants obtained from plants can be an attractive alternative to synthetic surfactants in the remediation of contaminated soils. In this research, a plant-based surfactant obtained from the fruit pericarp of Sapindus mukurossi, a tree generally grown in tropical regions of Asia, is tested. A simple and economical method for the preparation of the surfactant is developed. An empirical formula for the surfactant was determined to be (C26H31O10)n. The aqueous solubilities of hexachlorobenzene (HCB) and naphthalene in the natural surfactant solutions were found to vary linearly with the concentration of the surfactant showing trends comparable to that of typical com mercial surfactants. Natural surfactant solutions were also employed for flushing HCB from one-dimensional soil columns. HCB recoveries after 12 pore volumes of flushing with 0.5 and 1% natural surfactant solutions were 20 and 100 times more than that recovered by water flooding. These promising results warrant further re...

Soil Washing Potential of a Natural Surfactant

Data on the solubilization of p-dichlorobenzene (DCB), naphthalene, and biphenyl in aqueous solutions of sodium dodecylsulfate (SDS) (0-100 mM concentration) indicate increases in effective solubilities of these hydrophobic compounds by factors of roughly 20 to 100. DCB is effectively removed from spiked clay-sand mixtures by leaching with SDS solutions in laboratory columns. Surfactant solutions loaded with DCB are satisfactorily treated by gentle extraction with hexane, and the recovered surfactant solution satisfactorily solubilizes biphenyl. A simple model for predicting the solubilization behavior of surfactants is developed and tested experimentally.

Soil Clean Up by in-situ Surfactant Flushing. III. Laboratory Results

Competition authorities have recently placed an increasing emphasis on developing screening tools to pro-actively detect cartels through the analysis of procurement data. In light of this development, this article reviews the economics behind such screening tools together with strategic considerations for corporations seeking to develop and implement similar tools. Owing to their access to data and the known recent development of screens by competition authorities, the authors believe that, if corporations become active screeners, they could effectively contribute to the deterrence and detection of cartels. This should be in their own interest to do so as well. As part of the development and application of such screening tools, a close cooperation between competition authorities and corporations is advocated for each party to exchange experiences and to mutually benefit from the results of well-functioning screens.

/pdf/cartel-screening-can-competition-authorities-and-ikmbf1zm.pdf

O. Keith Gannon

Papers

Soil Clean Up by in-situ Surfactant Flushing. III. Laboratory Results

Cartel screening – can competition authorities and corporations afford not to use big data to detect cartels?