Degradation of polycyclic aromatic hydrocarbons in the presence of synthetic surfactants

Abstract

The biodegradation of polycyclic aromatic hydrocarbons (PAH) often is limited by low water solubility and dissolution rate. Nonionic surfactants and sodium dodecyl sulfate increased the concentration of PAH in the water phase because of solubilization. The degradation of PAH was inhibited by sodium dodecyl sulfate because this surfactant was preferred as a growth substrate. Growth of mixed cultures with phenanthrene and fluoranthene solubilized by a nonionic surfactant prior to inoculation was exponential, indicating a high bioavailability of the solubilized hydrocarbons. Nonionic surfactants of the alkylethoxylate type and the alkylphenolethoxylate type with an average ethoxylate chain length of 9 to 12 monomers were toxic to a PAH-degrading Mycobacterium sp. and to several PAH-degrading mixed cultures. Toxicity of the surfactants decreased with increasing hydrophilicity, i.e., with increasing ethoxylate chain length. Nontoxic surfactants enhanced the degradation of fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.

Effect of surfactant addition on phenanthrene biodegradation in sediments

“…The adverse effects of nonionic surfactants in this and other laboratory biodegradation experiments [26,28,29] suggest that a surfactant-microbial interaction inhibited phenanthrene mineralization by the surfactants.…”

“…1). Although decreased toxicity of nonionic surfactants with a greater number of ethoxyl groups has been reported [28], generalizations regarding surfactant structure-activity relationships should be made with caution.…”

Reductive dechlorination of chlorobenzenes in surfactant‐amended sediment slurries

“…Depending on the organism, substrate uptake may take place by one of the aforementioned modes or by a combination of modes. Microbes utilizing hydrocarbon directly through the aqueous phase can be limited by the rate of dissolution or desorption [3][4][5]. In the presence of micellized and/or microemulsified hydrocarbon the rate of microbial growth is often enhanced over growth in the presence of hydrocarbon alone [2,5].…”

“…Microbes utilizing hydrocarbon directly through the aqueous phase can be limited by the rate of dissolution or desorption [3][4][5]. In the presence of micellized and/or microemulsified hydrocarbon the rate of microbial growth is often enhanced over growth in the presence of hydrocarbon alone [2,5]. Increased mass transport due to an increase in substrate interfacial area is the reason generally given for this enhanced substrate utilization.…”

“…Most studies that have examined surfactant effects on microbial HOC degradation have looked at hydrocarbon utilization by pure cultures in aqueous media. Several of these studies, using a variety of nonionic surfactants, demonstrated a positive effect on microbial growth concurrent with enhanced degradation of hydrocarbon substrate [1,2,5,[11][12][13][14][15]. Generally, no evidence of surfactant degradation was observed.…”