The time-window - an inadequate criterion for the ready biodegradability assessment of technical surfactants

The attainment of the biodegradation pass-level within a distinct time peri od (10 days after the end of the lag-phase) is one of the criteria for asse ssing the ready biodegradability of chemical substances. The time-window as a simple approach for describing biodegradation kinetics is a poor descrip tor in the case of mixtures and poorly soluble compounds. Technically used surfactants are a mixture of numerous homologues and isomers and many are c omposed of two organic moieties which will be degraded sequentially. The as sociated problems in fulfilling the time-window requirement and the inadequ acy of this criterion for the ready biodegradability assessment of surfacta nts are illustrated and discussed. (C) 2001 Elsevier Science Ltd. All right s reserved.