In-Situ Surfactant/Surfactant-Nutrient Mix-Enhanced Bioremediation of NAPL (Fuel)-Contaminated Sandy Soil Aquifers

摘要

Scope and Background. Contamination of soils, aquifers and groundwater by nonaqueous phase liquid (NAPL) pollutants constitutes a major environmental issue of concern, worldwide. The residual (biodegradation-resistant) hydrophobic fuel hydrocarbons entrapped in the soil porous matrix, possess a particular bioremediation challenge due to their becoming virtually immobile, nor desorbable, or water dispersible. Consequently, they are not available as substrates to the micro-organism-based bio-degradation. Materials and Methods. Our research involves the development of economically feasible, surfactant/surfactant-nutrient mix (SSNM) - enhanced bioremediation methodologies for sustainable, in situ bioremediation of fuel-contaminated aquifers. This requires, methodologically, (a) the optimization, via in vitro 'flow' (columns) lab experiments and screening processes, of an effective mixture for the intended SSNM-enhanced bioremediation; and (b) the study of the combined effect of the optimized SSNM on the solubilization/mobilization and biodegradation of NAPL (fuel) in in vitro site/aquifer-simulated bioremediation. Results and Discussion. The essence of our findings: (1) kerosene's maximum enhanced mobilization - f = 3.6, compared with that of deionized water, was achieved with an SSNM having the composition of linear alkylbenzene sulfonate (LABS): coco-amphodiacetate (containing N): surfactant-nutrient X (containing both N and P) = 0.15: 0.15: 0.05 g/L, respectively; (2) 62-64 percent of the initial amount of kerosene in the initially saturated soil matrix, 'packed' in a column, has been eluted from it during -30 days, compared with 68 percent of kerosene biodegradation in 'vessel' settings, in 21 days.