EN
A quaternary ammonium salt (A), a bisquaternary (FB), and an amine oxide (B) were tested for biodegradability using bacterial strains isolated from a municipal waste-water treatment plant Adsorption of the compounds by the cells was distinguished from actual biodegradation. The bisquaternary hard detergent FB was of lower affinity to the bacterial cells in comparison to soft compound A, where adsorption is accompanied by degradation. A soft surfactant, amine oxide (B) is also degraded without marked adsorption by cells. Adsorption of the compouds by the cells is also lower in mineral biodegradation medius where cell membranes are stabilised by ions.