Assessment of anionic and nonionic surfactant removal by wastewater treatment plants using wet chemical methods

Surfactants are among the most common pollutants found in municipal and industrial wastewater, and their regular monitoring in wastewater and surface water is crucial for environmental protection. The presence of surfactants can negatively impact aquatic ecosystems, leading to biological imbalances and deterioration of water quality. Surfactant content was analyzed at a selected wastewater treatment plant in the Wielkopolska region (Poland). Results of anionic and nonionic surfactant determinations in municipal, industrial, and treated wastewater were presented. Anionic surfactants were determined using the standard and simplified MBAS method based on methylene blue, while nonionic surfactants were analyzed using the modified BiAS-thio method using thiourea. The indirect tensammetric method (ITM) was used as the reference method. The effectiveness of the methods for determining anionic and nonionic surfactants in raw and treated wastewater from a typical biological wastewater treatment plant was analyzed. The selected wastewater treatment plant in Greater Poland demonstrates high removal efficiency of anionic surfactants, exceeding 94%, and of nonionic surfactants, reaching 93% using the ITM method and 98% using the modified iodobismuthate BiAS-thio method. The retention time of sewage flowing into the treatment plant was one day.