MOBILIZATION AND COTRANSPORT OF PYRENE IN THE PRESENCE OF PSEUDOMONAS-AERUGINOSA UG2 BIOSURFACTANTS IN SANDY SOIL COLUMNS

Washing technologies are currently applied for the remediation of cont aminated soils. The efficiency of biosurfactants produced by Pseudomon as aeruginosa strains to mobilize some hydrocarbons sorbed on soils ha s already been demonstrated. However. few studies have been made to de fine optimal procedures for the injection of these rhamnolipids in soi l. This study examines (1) the efficiency of the biosurfactants produc ed by FI aeruginosa UG2 to mobilize pyrene from a contaminated sandy l oam as compared to that of sodium dodecyl sulfate (SDS); (2) the injec tion procedures (surfactant concentration, pore water velocity, contin uous or interrupted flow) that might affect the efficiency of pyrene m obilization using UG2 biosurfactants; and (3) the co-transport of UG2 biosurfactants and pyrene. The UG2 biosurfactants were more efficient for pyrene mobilization than SDS and had much less impact on soil. The mobilization of pyrene was approximately proportional to the mass of UG2 biosurfactants injected for both the 0.25% and the 0.50% (w/v) con centrations used. Pyrene mobilization was not greatly dependent on eit her the pore water velocity-about 5.9 and 10.2 inch/h (15 and 26 cm/h) -or the duration of flow interruption (5 or 15 h). suggesting that mob ilization was not rate limited under these conditions. The rhamnolipid s appeared to be weakly retained in the soil. Based on the experimenta l results, it would be advantageous to use a high UG2 biosurfactant co ncentration, a high pore water velocity, and possibly a flow interrupt ion of more than 15 h in order to reduce the injected volume and the d uration of the treatment required. The 0.25% UG2 biosurfactant concent ration greatly enhanced pyrene transport and could facilitate contamin ant recovery.