Removal of dimethylsulfide, n-hexane and toluene from waste air in a flat membrane bioreactor under continuous conditions

Dimethylsulfide (DMS), n-hexane and toluene removal from a waste air was carried out by using a flat composite membrane bioreactor under continuous feeding conditions. The composite membrane consisted of a dense polydimethylsiloxane top layer with an average thickness of 1.5 μm supported with a porous polyacrylonitrile layer of 50 μm. The membrane bioreactor (MBR) was operated during 9 months in which several operational conditions were applied. The inlet load of each compound ranged from 0 to 350 g m-3 h-1 and removal efficiencies of 80, 70 and 0 to 30 % were reached for DMS, toluene and hexane respectively. Two different empty bed residence time (EBRT) were applied on the MBR in order to check the influence of the residence time on the reactor performance. In this case, DMS and toluene removal increased with an increasing EBRT, while the removal of hexane remained constant. By increasing the flow rate of the recirculated liquid from 22 l min-1 to 45 l min-1, the total performance of the biofilter decreased. To increase the mass transfer of hexane in order to get a higher removal, an emulsion of water/silicone oil 80/20 V% was used as recirculated medium at the liquid side of the reactor. This caused a decrease in DMS removal while the removal of toluene remained constant. The variation on the hexane removal decreased significantly, so the reactor became more reliable for degrading hexane

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