Aerobic biodegradation of linear alkylbenzene sulfonates and sulfophenylcarboxylic acids for different salinity values by means of continuous assays

Aerobic biodegradation of linear alkylbenzene sulfonates (LAS) and sulfophenylcarboxylic acids (SPCs) in water, at different salinity values, has been studied. Three experiments have been carried out employing a staircase model system with continuous dosage of LAS to the system and using concentrations of LAS of the same order as those detected in littoral waters receiving urban wastewater discharges. LAS biodegradation was observed to be almost complete (showing a great extent), and in all cases exceeds 98.4%. At the very low concentration values of LAS utilized in the experiments, no significant variations in the biodegradation of LAS due to the effect of the different salinity values assayed were observed. The biodegradation intermediates detected for all the cases were sulfophenylcarboxylic acids with carboxylic chains of between five and 13 carbon atoms. The detection of C13-SPC (which is only produced by C13-LAS) confirms the existence of ω-oxidation. The total disappearance of SPCs in all cases indicates that mineralization of LAS at the concentrations tested was complete.