Target Analysis, Suspected-Target, and Non-Target Screening for Evaluation and Comparison of Full-Scale Ozonation at Three Wastewater Treatment Plants

The entry of micropollutants into the water cycle is of growing concern. This is also reflected by the EU Water Framework Directive and new guidelines for wastewater treatment plant effluents. Ozonation seems to be a good answer to this problem. The wastewater treatment plants Bad Sassendorf, Duisburg-Vierlinden and Schwerte were extended by a full-scale ozonation. Removal efficiency and process optimization were assessed by target analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS). Suspected-target and non-target screening using high resolution mass spectrometry (HRMS) were applied for chemical evaluation of transformation products and comparison of the three wastewater treatment plants. Data evaluation was done using an in-house created reference database as well as commercially and freely available databases. The different workflows are exemplarily discussed and a new concept using microscale two-dimensional liquid chromatography coupled to high resolution mass spectrometry is presented.