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

Quantitative carbon detector (QCD) for calibration-free, high-resolution characterization of complex mixtures

Current research of complex chemical systems, including biomass pyrolysis, petroleum refining, and wastewater remediation requires analysis of large analyte mixtures (>100 compounds). Quantification of each carbon-containing analyte by existing methods (flame ionization detection) requires extensive identification and calibration. In this work, we describe an integrated microreactor system called the Quantitative Carbon Detector (QCD) for use with current gas chromatography techniques for calibration-free quantitation of analyte mixtures. Combined heating, catalytic combustion, methanation and gas co-reactant mixing within a single modular reactor fully converts all analytes to methane (>99.9%) within a thermodynamic operable regime. Residence time distribution of the QCD reveals negligible loss in chromatographic resolution consistent with fine separation of complex mixtures including cellulose pyrolysis products.

Liquid chromatography–(tandem) mass spectrometry for the follow-up of the elimination of persistent pharmaceuticals during wastewater treatment applying biological wastewater treatment and advanced oxidation

The persistent and hardly eliminable pharmaceutical compounds carbamazepine, diazepam, diclofenac and clofibric acid were monitored in municipal wastewater by electrospray LC-MS and LC-MS-MS in positive and negative mode under high resolution and high mass accuracy conditions. While biological treatment by conventional and membrane bioreactors failed, the advanced oxidation methods using ozone (O3), O3/UV or hydrogen peroxide in combination with UV (H2O2/UV) successfully led to the complete elimination of these compounds. Target compounds could be confirmed as permanently present pollutants in Aachen-Soers wastewater in concentrations between 0.006 and 1.9 microg l(-1). Pharmaceuticals were determined after extraction using either C18 solid-phase extraction or by directly injecting them into the column without pre-concentration, achieving limits of quantification of 0.001 or 0.00001 microg l(-1), respectively.

Removal of a broad range of surfactants from municipal wastewater--comparison between membrane bioreactor and conventional activated sludge treatment

Elimination of alkylphenol ethoxylates (APEO) and their degradation products (alkylphenols and alkylphenoxy carboxylates), as well as linear alkylbenzene sulfonates (LAS) and coconut diethanol amides (CDEA), was studied in a pilot plant membrane bioreactor (MBR) working in parallel to a full-scale wastewater treatment plant (WWTP) using conventional activated sludge (CAS). In the CAS system 87% of parent long ethoxy chain NPEOs were eliminated, but their decomposition yielded persistent acidic and neutral metabolites which were poorly removed. The elimination of short ethoxy chain NPEOs (NP(1)EO and NP(2)EO) averaged 50%, whereas nonylphenoxy carboxylates (NPECs) showed an increase in concentrations with respect to the ones measured in influent samples. Nonylphenol (NP) was the only nonylphenolic compound efficiently removed (96%) in the CAS treatment. On the other hand, MBR showed good performance in removing nonylphenolic compounds with an overall elimination of 94% for the total pool of NPEO derived compounds (in comparison of 54%-overall elimination in the CAS). The elimination of individual compounds in the MBR was as follows: 97% for parent, long ethoxy chain NPEOs, 90% for short ethoxy chain NPEOs, 73% for NPECs, and 96% for NP. Consequently, the residual concentrations were in the low mug/l level or below it. LAS and CDEA showed similar elimination in the both wastewater treatment systems that were investigated, and no significant differences were observed between the two treatment processes. Nevertheless, for all studied compounds the MBR effluent concentrations were consistently lower and independent of the influent concentrations. Additionally, MBR effluent quality in terms of chemical oxygen demand (COD), NH(4)(+) concentration and total suspended solids (TSS) was always superior to the ones of the CAS and also independent of the influent quality, which demonstrates high potential of MBRs in the treatment of municipal wastewaters.

Biodegradation studies of selected priority acidic pesticides and diclofenac in different bioreactors

The biodegradation of selected priority acidic pesticides MCPP, MCPA, 2,4-D, 2,4-DP and bentazone and the acidic pharmaceutical diclofenac was investigated using a membrane bioreactor (MBR) and a fixed-bed bioreactor (FBBR). A pilot plant MBR was fed with raw water spiked with the selected compounds. The experiment was repeated every week during four weeks to enhance the adaptation of microorganisms. In order to further study the biodegradability of these compounds, degradation studies in a FBBR were carried out. All the samples were analysed by solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). The results indicate that in the MBR compounds except for bentazone were eliminated within the first day of the experiment at rates ranging from 44% to 85%. Comparing these results with the degradation rates in the FBBR showed that in the latter only MCPP, MCPA 2,4-D and 2,4-DP were degraded after a much longer adaptation phase of microorganisms.

Analysis of persistent organic pollutants in marine sediments using a novel microwave assisted solvent extraction and liquid-phase microextraction technique

A simple and novel analytical method for quantifying persistent organic pollutants (POPs) in marine sediments has been developed using microwave assisted solvent extraction (MASE) and liquid-phase microextraction (LPME) using hollow fibre membrane (HFM). POPs studied included twelve organochlorine pesticides (OCP) and eight polychlorinated biphenyl (PCB) congeners. MASE was used for the extraction of POPs from 1 g of sediment using 10 ml of ultrapure water at 600 W for 20 min at 80 degrees C. The extract was subsequently subjected to a single step LPME-HFM cleanup and enrichment procedure. Recovery varied between 73 and 111% for OCPs; and 86-110% for PCBs, and exceeded levels achieved for conventional multi-step Soxhlet extraction coupled with solid-phase extraction. The method detection limit for each POP analyte ranged from 0.07 to 0.70 ng g(-1), and peak areas were proportional to analyte concentrations in the range of 5-500 ng g(-1). Relative standard deviations of less than 20% was obtained, based on triplicate sample analysis. The optimized technique was successfully applied to POP analysis of marine sediments collected from the northeastern and southwestern areas of Singapore's coastal environment.

Determination of non-ionic polyethoxylated surfactants in wastewater and river water by mixed hemimicelle extraction and liquid chromatography–ion trap mass spectrometry

The capability of hemimicelles-based solid phase extraction (SPE)/liquid chromatography/atmospheric pressure chemical ionisation in positive mode, ion trap mass spectrometry (LC/(APCl+-IT)-MS) for the concentration, separation and quantitation of non-ionic surfactants has been investigated. Concentration was based on the formation of mixed aggregates of analytes [alkylphenol ethoxylates (APE, octyl and nonyl) and alkyl ethoxylates (AE, C12-C16)] with the anionic surfactant sodium dodecyl sulphate (SDS) that is adsorbed on alumina. Parameters affecting SPE were investigated on the basis that hemimicelles are dynamic entities in equilibrium with the aqueous phase. The performance of ion trap mass spectrometry for MS and MS/MS quantitation of non-ionic homologues was assessed. Recoveries of analytes from wastewater influent and effluent and river water samples ranged between 91 and 98% and were found independent on the length of the alkyl chain under the optimised conditions. Anionic surfactants did not interfere to the levels found in environmental samples. The detection limits ranged between 14 and 111 ng/l for wastewater influent, 10 and 40 for wastewater effluent and 4 and 35 for river water, after concentration of 250, 500 and 750 ml of sample, respectively. The approach was applied to the determination of AE and APE in influent and effluent samples from four wastewater treatment plants and four river samples. The concentrations of individual non-ionic surfactants found ranged between 0.3 and 373 microg/l.

Elucidation of the behavior of tannery wastewater under advanced oxidation conditions

Diverse advanced oxidation process (AOP) techniques applying UV, TiO2/UV, O3 and O3/UV were used to degrade pollutants contained in tannery wastewater. The total mineralization of these pollutants is desirable, but it is quite energy consuming and sometimes impossible. Therefore the objective was to achieve an enhancement of biodegradability, preferentially with a decrease in toxicity in parallel. This work demonstrates that the dominant pollutants were chemically degraded by oxidation, while changes in carbon content were only marginal. These results were obtained monitoring the total organic carbon content (TOC), chemical and biochemical oxygen demand (COD and BOD), and substance-specific pollutant content by application of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography/mass spectrometry (LC-MS). Daphnia magna toxicity testing performed in parallel proved a decrease in toxicity after AOP treatment of the tannery wastewater.

Liquid chromatography-(tandem) mass spectrometry of selected emerging pollutants (steroid sex hormones, drugs and alkylphenolic surfactants) in the aquatic environment

Among the various compounds considered as emerging pollutants, alkylphenolic surfactants, steroid sex hormones, and pharmaceuticals are of particular concern, both because of the volume of these substances used and because of their activity as endocrine disruptors or as causative agents of bacterial resistance, as is the case of antibiotics. Today, the technique of choice for analysis of these groups of substances is liquid-chromatography coupled to mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS-MS). In the last decades, this technique has experienced an impressive progress that has made possible the analysis of many environmental pollutants in a faster, more convenient, and more sensitive way, and, in some cases, the analysis of compounds that could not be determined before. This article reviews the LC-MS and LC-MS-MS methods published so far for the determination of alkylphenolic surfactants, steroid sex hormones and drugs in the aquatic environment. Practical considerations with regards to the analysis of these groups of substances by using different mass spectrometers (single quadrupole, ion trap and triple quadrupole instruments, etc.), interfaces and ionization and monitoring modes, are presented. Sample preparation aspects, with special focus on the application of advanced techniques, such as immunosorbents, restricted access materials and molecular imprinted materials, for extraction/purification of aquatic environmental samples and extracts are also discussed.

Recent advances in the mass spectrometric analysis related to endocrine disrupting compounds in aquatic environmental samples

An overview of mass spectrometric methods used for the determination of endocrine disrupting compounds (EDCs) in environmental samples is presented. Among the EDCs we have selected five groups of compounds that are of priority within European Union and US research activities: alkylphenols, polychlorinated compounds (dioxins, furans and biphenyls), polybrominated diphenyl ethers, phthalates and steroid sex hormones. Various aspects of current LC-MS and GC-MS methodology, including sample preparation, are discussed.

Analysis of ethoxylated nonionic surfactants and their metabolites by liquid chromatography/atmospheric pressure ionization mass spectrometry

The widespread use and questionable environmental acceptability of nonionic surfactants make the alkylphenol ethoxylates (APEOs) and their neutral and acidic degradation products a focus of interest in environmental analytical chemistry. The characterization and especially quantification of polyethoxylate mixtures in environmental matrices is a challenge, because of the complexity of the mixtures. A review on trace analysis of APEOs using atmospheric pressure ionization mass spectrometry, including sample preparation and liquid chromatographic separation, is presented. In this Special Feature, the performances of two ionization methods, atmospheric pressure chemical ionization and electrospray ionization, is discussed in terms of selectivity and sensitivity toward oligomeric mixtures of APEOs. Capabilities and limitations associated with the liquid chromatographic/mass spectrometric detection of APEOs, their main degradation products and their halogenated metabolites, and also specific issues related to the sample preparation, formation of fragments, adducts and cluster ions, quantification of oligomeric mixtures and signal suppression effects in complex matrices, are discussed. Conclusions and future perspectives are outlined.