Influence of nonionic surfactant on attached biofilm formation and phenanthrene bioavailability during simulated surfactant enhanced bioremediation.

Surfactant effects on preformed attached biofilm formation and the biodegradation of soil-sorbed phenanthrene were monitored using a continuously flowing flowcell system. Thirty-two flowcell reactors were constructed to monitor phenanthrene degradation and biofilm formation under five different surfactant concentrations. Initially, all flowcell reactors were operated without surfactant for 25 days to allow for the formation of an attached bacterial biofilm on phenanthrene spiked soil; after that, a model nonionic surfactant (Triton X-100) was applied to the flowcell reactors at five different concentrations (0, 100, 200, 500, and 1000 mg/L), which represent concentrations below (0 and 100 mg/L) and above (200, 500, and 1000 mg/L) the critical micelle concentration (cmc). The results obtained in this study reveal that bacterial biofilm formation with extracellular polymeric substances was the strategy of bacteria to utilize partially soluble PAHs. However, in the presence of surfactant, this strategy was modified. The presence of surfactant at all concentrations changed the physiological aspects of the attached biofilm, and the bioavailability of the phenanthrene increased with the addition of surfactant above the cmc.