Comparative studies on the anaerobic biodegradations of anionic and nonionic surfactants.

Abstract

We examined anaerobic biodegradations of sodium linear alkylbenzenesulfonate (LAS), sodium alkyl sulfate (AS), sodium alkylpoly (oxyethylene) sulfate (AES), sodium alkylphenyl (oxyethylene) sulfate (NES), sodium α-olefinsulfonate (AOS), sodium salt of fatty acid (Soap), alkyl poly (oxyethylene) ether (AE) and p-alkylphenyl poly (oxyethylene) (APE) by bacterial sources from sewage sediments. In the course of biodegradation, the productions of H2, H2S, CO2 and CH4 were determined. Assuming that the final products were CO2 and CH4, the results of the anaerobic biodegradabilities of surfactants were as follows : (AS, Soap)>AE>(APE, AES, NES)>(AOS, LAS). These results indicated that the surfactant having benzene ring, branched alkyl chain or ethoxylate chain [-(EO)n-] was resistant to anaerobic biodegradations. The biodegradability of surfactants was also influenced by the structure of hydrophilic group. When the hydrophobic group was identical, the extent of biodegradation decreased in the following order : -OSO3Na>-(EO)nH>-(EO)nSO3Na, -SO3Na.