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The present work focuses on the remediation of contaminated aquifers by hydrophobic organic contaminants, such as hydrocarbons or chlorinated solvents, following the approach of Surfactant Enhanced Aquifer Remediation (SEAR) technology, based on the use of surfactants for the solubilization and mobilization of pollutants. In this context, surfactin, a lipopeptide biosurfactant produced by Bacillus Subtilis, was selected as reference material for the NAPLs mobilization study. After a preliminary characterization of surfactin for the experimental evaluation of its physicochemical parameters (critical micelle concentration and surface behavior), the study involved in a batch configuration test in which toluene and perchloroethylene adsorption on a porous material was investigated in the presence and in the absence of surfactin as an indirect way to evaluate mobilization ability of surfactin through the reduction of NAPLs adsorption. Experimental measurements highlighted a relatively low CMC value (2.45 x 10-2 g L-1 ) and a great tendency of surfactin to adsorb at the surfaces or interfaces. The batch test showed that the surfactin solution had no effects on the adsorption of toluene and PCE. On the other hand, surfactin led to an important decrease in the affinity between dissolved pollutants and solid surface. In general, these results suggest the possibility of using surfactin in the enhanced surfactant remediation technology. [ABSTRACT FROM AUTHOR]

This study presents the proof-of-concept of the "Oil-Spill Snorkel": a novel bioelectrochemical approach to stimulate the oxidative biodegradation of petroleum hydrocarbons in sediments. The "Oil-Spill Snorkel" consists of a single conductive material (the snorkel) positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated sediment) and the oxic zone (the overlying O2-containing water). The segment of the electrode buried within the sediment plays a role of anode, accepting electrons deriving from the oxidation of contaminants. Electrons flow through the snorkel up to the part exposed to the aerobic environment (the cathode), where they reduce oxygen to form water. Here we report the results of lab-scale microcosms setup with marine sediments and spiked with crude oil. Microcosms containing one or three graphite snorkels and controls (snorkel-free and autoclaved) were monitored for over 400 days. Collectively, the results of this study confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1.7-fold increase (p = 0.023, two-tailed t-test) in the cumulative oxygen uptake and 1.4-fold increase (p = 0.040) in the cumulative CO2 evolution in the microcosms containing three snorkels compared to snorkel-free controls. Accordingly, the initial rate of total petroleum hydrocarbons (TPH) degradation was also substantially enhanced. Indeed, while after 200 days of incubation a negligible degradation of TPH was noticed in snorkel-free controls, a significant reduction of 12 ± 1% (p = 0.004) and 21 ± 1% (p = 0.001) was observed in microcosms containing one and three snorkels, respectively. Although, the "Oil-Spill Snorkel" potentially represents a groundbreaking alternative to more expensive remediation options, further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify suitable configurations for field applications. [ABSTRACT FROM AUTHOR]