Fate of secondary alkane sulfonate surfactants during municipal wastewater treatment

A field study was conducted to determine the mass flow of secondary alkane sulfonate (SAS) surfactants in a municipal wastewater treatment plant. The concentration of SAS in samples of sewage (raw sewage, primary and secondary effluent) was determined using solid-phase extraction with C18 disks and injection port derivatization with gas chromatography/mass selective detection (GC/MS). The concentration of SAS in raw and anaerobically-digested sludge was determined by ion-pair/supercritical fluid extraction and injection-port derivatization GC/MS. The removal of SAS from the waste stream is efficient (99.7%) with approximately 16% (w/w) transferred to sludge. Given current Swiss sludge disposal regulations, a maximum of approximately 350 mg m−2 SAS are applied every three years to a given section of agricultural soil. Of the total SAS mass flow entering the treatment plant, an average of 0.3% (w/w) is discharged to the adjacent receiving water stream.