Toxic effect of surfactants and probable products of their biodegradation on methanogenesis in an anaerobic microbial community

Surfactants used in household and various industries, are rather toxic; therefore, the accumulation of these compounds in the environment through wastewaters has challenged the problem of their biodegradation. In this research, an attempt was made to assess the toxic effect of various surfactants and the likely products of their biodegradation on the acetoclastic methanogens of an anaerobic microbial community. Among the substances investigated, cationic surfactants were found to be most toxic to methanogens: 154 mg/l alkamon DS and 345 mg/I catamin AB induced a 50% inhibition of methanogenesis. Toxicity studies of some aromatic and cyclic compounds, as the probable products of biodegradation of alkylbenzene sulfonate surfactants, showed that methanogenesis in the microbial community under study are rather tolerant to high concentrations of these compounds.