Pretreatment of secondary effluents in view of optimal ozone-based AOP removal of trace organic contaminants : bench-scale comparison of efficiency and energy consumption

This study compares the performance of several ozone-based advanced oxidation processes (AOPs), in combination with filtration, in terms of trace organic contaminant (TrOC) removal efficiency and energy and cost requirement. It was shown that the hydroxyl radical ((OH)-O-center dot) scavenging rate of the secondary wastewater effluent decreased as a result of an additional pretreatment step, leading to an increase of ozone and (OH)-O-center dot exposures at the same ozone dose. Adding filtration such as sand filtration or granular activated carbon filtration (GACF) as a pretreatment increased the removal efficiency of TrOCs by all tested ozone-based AOPs and reduced the minimum effective ozone dose for TrOC elimination. When the applied ozone dose is more than this minimum effective ozone dose, the elimination of TrOCs can be observed. For example, because of the use of anion resin filtration, 17 alpha-ethinylestradiol elimination contributed by the process of ozone-based AOP increased from 34.6 to 42.1% at an ozone dose of 1.0 g O-3/g dissolved organic carbon. Ozone-based AOPs coupled with filtration as a pretreatment were found to be more cost-efficient than the single AOPs at all ozone dose levels. The energy consumption of ozone-based AOPs was decreased by more than 25% when applying GACF as a pretreatment. In comparison with other filtration techniques, the pretreatment of secondary effluents by GACF before ozonation was proven to be the most cost-effective method for TrOC elimination

Multi-residue analysis of pharmaceuticals in Belgian surface water : a novel screening-to-quantification approach using large-volume injection liquid chromatography coupled to high-resolution mass spectrometry

The ever growing number of emerging micropollutants such as pharmaceuticals requests rapid and sensitive full-spectrum analytical techniques. Time-of-flight highresolution mass spectrometry (TOF-HRMS) is a promising alternative for the state-ofthe- art MS/MS instruments because of its ability to simultaneously screen towards a virtually unlimited list of suspect compounds and to perform target quantification. The challenge for such suspect screening is to develop a strategy which minimizes the false negative rate without restraining numerous false positives. At the same time, omitting laborious sample enrichment through large-volume injection ultraperformance liquid chromatography (LVI-UPLC) is advantageous avoiding selective preconcentration. A novel suspect screening strategy was developed using LVI-UPLC-TOF-MS aiming the detection of 69 multi-class pharmaceuticals in surface water without the a priori availability of analytical standards. As a novel approach, the screening takes into account the signal intensity-dependent accurate mass error, hereby assuring the detection of 95% of pharmaceuticals present in surface water. Subsequently, the validation and applicability of the full-spectrum method for target quantification of the 69 pharmaceuticals in surface water is discussed. Analysis of five Belgian river water samples revealed the occurrence of 17 pharmaceuticals in a concentration range of 17 ng L-1 up to 3.1 μg L-1