Biodegradation of naphthalene in aqueous nonionic surfactant systems

Abstract

The principal objective of this study was to quantify the bioavailability of micelle-solubilized naphthalene to naphthalene-degrading microorganisms comprising a mixed population isolated from contaminated waste and soils. Two nonionic surfactants were used, an alkylethoxylate, Brij 30 (C 12 E 4), and an alkylphenol ethoxylate, Triton X-100 (C 8 PE 9.5). Batch experiments were used to evaluate the effects of aqueous, 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 solubilization and biodegradation under aerobic conditions was monitored by radiotracer and spectrophotometric techniques. Experimental results showed that surfactant concentrations above the critical micelle concentration were not toxic to the naphthalene-degrading bacteria and that the presence of surfactant micelles did not inhibit mineralization of naphthalene. Naphthalene solubilized by micelles of Brij 30 or Triton X-100 in liquid media was bioavailable and degradable by the mixed culture of bacteria.

Microbial surfactants and their use in field studies of soil remediation

“…The more hydrophobic surfactants exhibited better solubilizing properties. Contradictory results have been obtained from tests on biodegradability of PAH solubilized by synthetic surfactants (Liu et al 1995). Tiehm (1994) showed that bacteria were less tolerant to the more hydrophobic surfactants.…”

Toxicity of phenanthrene dissolved in nonionic surfactant solutions toPseudomonas putidaP2

“…There have been a number of studies on the effectiveness of surfactants on biodegradation of PAHs, but results are inconclusive. Some reports have demonstrated that nonionic surfactants stimulate the biodegradation of PAH in liquid or soil systems (Guerin & Jones, 1988;Tiehm, 1994;Liu et al, 1995;Sartoros et al, 2005). However, in other cases the presence of surfactants resulted in no or decreased PAH degradation (Tiehm, 1994;Lei et al, 2005;Li & Bai, 2005;Sartoros et al, 2005).…”

Polycyclic aromatic hydrocarbon behavior in bioactive soil slurry reactors amended with a nonionic surfactant

“…A number of investigators have demonstrated that surfactants can enhance bioavailability of PAHs by increasing rates of their mass transfer (e.g., dissolution or desorption) to the aqueous phase in which microbial uptake occurs [2][3][4][5], or micelle-associated PAHs are directly available to PAH-degrading microbes via direct contact between micelles and microbes [6,7]. The extent of stimulation varies with the type and concentration of surfactants and the type of microorganisms involved [8][9][10][11][12][13]. Conversely, others have reported surfactant additions to inhibit, or at least not enhance, PAH biodegradation [14][15][16][17][18].…”