BIODEGRADATION OF NAPHTHALENE IN AQUEOUS NONIONIC SURFACTANT SYSTEMS

The principal objective Of this study was to quantify the bioavailabil ity of micelle-solubilized naphthalene to naphthalene-degrading microo rganisms comprising a mixed population isolated from contaminated wast e and soils. Two nonionic surfactants were used, an alkylethoxylate, B rij 30 (C(12)E(4)), and an alkylphenol ethoxylate, Triton X-100 (C(8)P E(9.5)). Batch experiments were used to evaluate the effects of aqueou s, micellized nonionic surfactants on the microbial mineralization of naphthalene and salicylic acid, an intermediate compound formed in the pathway of microbial degradation of naphthalene. The extent of solubi lization and biodegradation under aerobic conditions was monitored by radiotracer and spectrophotometrie techniques. Experimental results sh owed,ved that surfactant concentrations above the critical micelle con centration were not toxic to the naphthalene-degrading bacteria and th at the presence of surfactant micelles did not inhibit mineralization of naphthalene. Naphthalene solubilized by micelles of Brij 30 or Trit on X-100 in liquid media was bioavailable and degradable by the mixed culture of bacteria.