Transport of a bacterial suspension through a soil matrix using water and an anionic surfactant

Down-flow column studies were used in this research to investigate the ability of an anionic surfactant, sodium dodecylbenzene sulfonate (DDBS), to facilitate transport of an isolate of Pseudomonas pseudoalcaligenes through a processed soil matrix under pressurized flow. The influences of bacterial density and the volume of bacterial suspension pumped were examined to determine their influence on bacterial transport in soil. Experiments were conducted using 6.35 cm diameter by 30 cm long stainless steel columns packed with a sandy clay loam. Bacterial suspensions were prepared using either water or surfactant solutions. The surfactant solution enhanced the transport of bacteria through soil columns at both bacterial densities of the pumping solution (10¹⁰ and 10⁸ cfu/ml) tested. Pumping a higher density of bacteria increased the number of bacteria recovered at all depths when either water or surfactant solutions were used. Increasing the volume of bacterial suspension pumped appears to cause significant pore blockage when water is used as the pumping suspension. However, use of DDBS facilitated the transport of bacteria by apparently reducing the extent of pore blockage.