Simultaneous extraction and fate of linear alkylbenzene sulfonates, coconut diethanol amides, nonylphenol ethoxylates and their degradation products in wastewater treatment plants, receiving coastal waters and sediments in the Catalonian area (NE Spain)

Abstract

The efficiency of six wastewater treatment plants (WWTPs) in the Catalonian region to remove several classes of ionic and non-ionic surfactants was investigated, using solid-phase extraction (SPE) followed by liquid chromatography–mass spectrometry (LC–MS). Occurrence and distribution of linear alkylbenzene sulfonates (LASs), coconut diethanol amides (CDEAs), nonylphenol ethoxylates (NPEOs) and their degradation products were studied in coastal areas receiving WWTP effluents. For the analysis of sediment samples pressurized liquid extraction (PLE) followed by SPE extract clean-up and LC–MS detection was used for simultaneous extraction of all target compounds. Concentrations of parent long ethoxy chain NPEOs in raw water entering WWTPs ranged from 60 to 190 μg/L. In effluents concentrations ranged from 2.8 to 6.6 μg/L, which corresponded to an average primary elimination of 93–96%. Nonylphenol (NP) was found in concentrations from 0.2 to 18 μg/L in WWTP influents and up to 5 μg/L in the treated water, showing a clear declining trend with respect to concentrations reported in the last 5 years. The elimination of LASs and CDEAs varied depending on the WWTP and was higher than 85% in well operated WWTPs with secondary treatment and only 56% (for CDEAs) and 30% (for LAS) in WWTPs with primary treatment. Levels up to 86 mg/kg of LAS, 1.7 mg/kg of NP, 400–760 μg/L for NPEOs and NPECs were detected in sediments at sampling points near the discharge of WWTP effluents, clearly showing that in coastal area receiving WWTP effluents surfactants and their degradation products are widespread contaminants.