Assessment of the pollutant elimination efficiency by gas chromatography/mass spectrometry, liquid chromatography-mass spectrometry and -tandem mass spectrometry - Comparison of conventional and membrane-assisted biological wastewater treatment processes

The elimination efficiency of advanced conventional biological wastewater t reatment was compared to membrane-assisted biological wastewater treatment. The sum parameter analyses dissolved organic carbon (DOC) and chemical oxy gen demand (COD) or substance-specific analyses such as gas chromatography combined with mass spectrometry, flow injection analysis (FIA-MS) and liqui d chromatography (LC-MS) in combination with mass or tandem mass spectromet ry (MS-MS) were applied to assess elimination of hardly eliminable compound s in both types of wastewater treatment plants (WWTP). Reduction of DOC and COD in wastewater treatment processes confirmed a favourable elimination e fficiency. Substance-specific methods which were applied in addition permit ted a qualitative and semi-quantitative assessment of elimination with a vi sual pattern recognition approach. In order to identify pollutants either t he MST library of electron impact mass spectra for unpolar compounds or the laboratory-made collision-induced dissociation spectra Library for polar p ollutants was used. To assess elimination efficiency FIA-MS in the selected ion monitoring mode (SIM) besides high selective substance-specific mass s pectrometric techniques such as parent ion scans and neutral loss scans wer e used for quantification. Results proved that membrane-assisted treatment was more effective than advanced biological treatment. In both types of WWT Ps predominantly unpolar pollutants were eliminated, while all effluents we re dominated by polar compounds of anthropogenic and biogenic origin. These unpolar and polar compounds which had been identified as hardly eliminable are reported about. Quantitative results obtained by FIA-MS, LC-MS and MS- MS for the elimination of alkyl polyglycol ethers, nonylphenol ethoxylates and linear alkylbenzenesulfonic acids from wastewater are presented. (C) 20 00 Elsevier Science B.V. All rights reserved.