Monitoring of Anionic Surfactants in a Wastewater Treatment Plant of Algiers Western Region by a Simplified Spectrophotometric Method

Evaluation of anionic surfactant (AS) quantities in the environment has been the subject of intensive worldwide investigation. Even so, significant questions related to their presence in Algerian wastewaters discharged into the Mediterranean Sea remain. For the first time, monitoring of AS in a wastewater treatment plant (WWTP) located about 30 km west of Algiers was carried out. Four sampling points were selected to inspect the behavior of AS and investigate surfactant removal efficiencies of the WWTP: untreated wastewaters (UW), samples clarified via primary treatment, samples biologically treated and treated waters. To achieve this work, a spectrophotometric method of AS determination has been developed. Dioctyl sulfosuccinate sodium was chosen as a reference because of its low costs and its high response, compared to other AS commonly used by this method. The effects of pH, time of extraction, and washing step were studied. The volume of solvent was optimized. The calibration curve was linear and exhibited a significant coefficient of correlation. The lower limit of detection was found to be around 10 −6 M. Mechanical and biological treatments remove 53 % of AS from wastewaters before being discharged into the aquatic environment. It was found that the concentration of AS discharged into the Mediterranean Sea in the studied region reaches 10 −4 M.