ENHANCED TRANSPORT OF BACTERIA THROUGH A SOIL MATRIX USING COLLOIDAL GAS APHRON SUSPENSIONS

The influence of an anionic surfactant sodium dodecylbenzene sulfonate (DDBS) in the form of either an aqueous solution or microgas dispersi on known as colloidal gas aphron (CGA) on the transport of a Pseudomon as pseudoalcaligenes strain through a saturated soil matrix was examin ed. The experiments were conducted in 30-cm-long and 6.35 cm internal diameter stainless steel columns packed with a sandy clay loam. A 10-m l pulse (0.033 pore volumes) of a bacterial suspension containing 10(1 0) colony forming units (cfu) per mi was injected, and the column was eluted with either deionized water, a solution of DDBS, or a CGA suspe nsion ata surface loading rate of 0.16 cm/min. The bacterial distribut ions within the column were similar after the passage of the water and surfactant solutions; however, the distribution of bacteria ill the c olumns and effluent after the passage of the CGA suspension was marked ly enhanced. The bacterial concentration in the lower half of the colu mn after the passage of the CGA suspension was 2 to 3 orders of magnit ude higher than that observed for either the surfactant or water solut ions under similar experimental conditions. The final bacterial densit y in the effluent after the passage of the surfactant solution was one -half order of magnitude greater than that in the effluent produced by passage of water. After the passage of the CGA suspension, the total number of bacteria in the effluent was at least 2 or 3 orders of magni tude greater than that obtained by passage of either surfactant or wat er as the eluting agent, respectively. The results of the study sugges ts that CGA suspensions can transport bacteria more efficiently than c onventional surfactant solutions or water.