FATE OF SURFACTANTS IN ACTIVATED-SLUDGE WASTE-WATER TREATMENT PLANTS - OUTCOME OF FIELD STUDIES

An extensive monitoring programme was conducted in seven Dutch municip al sewage treatment plants to determine the environmental concentratio ns of the main types of surfactants, including linear alkylbenzene sul phonate (LAS), alcohol ethoxylates (AE), alcohol ethoxy sulphates (AES ), alcohol sulphates (AS) and soap. All surfactants were removed by mo re than 99 % during sewage treatment. The concentrations of the surfac tants in the treated sewage averaged 39 mu g/l for LAS, 6.2 mu g/l far AE, 6.5 mu g/l far AES, 5.7 mu g/l for AS and 174 mu g/l for soap. Th e measured effluent concentrations were used to determine the frequenc y distribution of surfactants in the receiving river water. In additio n the monitoring study demonstrated that a significant part of the sur factants were degraded in the sewer.