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130 Ergebnisse
Bereich: Suchergebnisse
Publikation Organic photovoltaics: Potential fate and effects in the environment(Elsevier, 2012) Zimmermann, Yannick-Serge; Schäffer, Andreas; Hugi, Christoph; Fent, Karl; Corvini, Philippe; Lenz, MarkusIn times of dwindling fossil fuels it is particularly crucial to develop novel “green” technologies in order to cover the increasing worldwide demand for energy. Organic photovoltaic solar cells (OPVs) are promising as a renewable energy source due to low energy requirement for production, low resource extraction, and no emission of greenhouse gasses during use. In contrast to silicium-based solar cells, OPVs offer the advantages of light-weight, semi-transparency and mechanical flexibility. As to a possible forthcoming large-scale production, the environmental impact of such OPVs should be assessed and compared to currently best available technologies. For the first time, this review compiles the existing knowledge and identifies gaps regarding the environmental impact of such OPVs in a systematic manner. In this regard, we discuss the components of a typical OPV layer by layer. We discuss the probability of enhanced release of OPV-borne components into the environment during use-phase (e.g. UV- and biodegradation) and end-of-life phase (e.g. incineration and waste disposal). For this purpose, we compiled available data on bioavailability, bioaccumulation, biodegradation, and ecotoxicity. Whereas considerable research has already been carried out concerning the ecotoxicity of certain OPV components (e.g. nanoparticles and fullerenes), others have not been investigated at all so far. In conclusion, there is a general lack of information about fate, behavior as well as potential ecotoxicity of most of the main OPV components and their degradation/transformation products. So far, there is no evidence for a worrying threat coming from OPVs, but since at present, no policy and procedures regarding recycling of OPVs are in action, in particular improper disposal upon end-of-life might result in an adverse effect of OPVs in the environment when applied in large-scale.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation 01B - Beitrag in Magazin oder ZeitungPublikation Opciones para el aprovechamiento energético de residuos en la gestión de residuos sólidos urbanos. Guía para los responsables de la toma de decisiones en países en vías de desarrollo y emergentes(Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, 2017) Mutz, Dieter; Hengevoss, Dirk; Hugi, Christoph; Gross, Thomas05 - Forschungs- oder ArbeitsberichtPublikation Progress in sensor technology - progress in process control? Part I: Sensor property investigation and classification(IWA Publishing, 2003) Rieger, Leiv; Alex, Jens; Winkler, S.; Boehler, Marc; Thomann, Michael; Siegrist, H.To ensure correctly operating control systems, the measurement and control equipment in WWTPs must be mutually consistent. The dynamic simulation of activated sludge systems could offer a suitable tool for designing and optimising control strategies. Ideal or simplified sensor models represent a limiting factor for comparability with field applications. More realistic sensor models are therefore required. Two groups of sensor models are proposed on the basis of field and laboratory tests: one for specific sensors and another for a classification of sensor types to be used with the COST simulation benchmark environment. This should lead to a more realistic test environment and allow control engineers to define the requirements of the measuring equipment as a function of the selected control strategy.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Spectral in-situ analysis of NO2, NO3, COD, DOC and TSS in the effluent of a WWTP(IWA Publishing, 2004) Rieger, Leiv; Langergraber, Günter; Thomann, Michael; Fleischmann, Nikolaus; Siegrist, HansruediAn in-situ UV spectrometer was applied to the effluent of a WWTP in Switzerland and calibrated using a multivariate calibration algorithm based on PLS regression. Except for nitrite, the calibration was based on comparative measurements of the effluent in the plant laboratory. Samples made of stock solution added to three different matrices prepared in the EAWAG laboratory were used for the nitrite calibration because the effluent concentrations were always in the range of 0.06–0.26 mg/l. The results show very good precision for nitrite and nitrate. The measuring range for COD and DOC was not completely covered by the measurements, so the meaningfulness of the results is limited. Nevertheless the precision obtained for soluble COD is high enough for most applications at WWTPs. The accuracy of the TSS measurement is unsatisfactory as regards effluent limits since the spectrometer used does not cover the wavelength region up to 700 nm, which gives better signals for TSS calibration due to its strong correlation with turbidity.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Computer-aided monitoring and operation of continuous measuring devices(IWA Publishing, 2004) Rieger, Leiv; Thomann, Michael; Joss, Adriano; Gujer, Willi; Siegrist, HansruediExtended studies of measuring and control systems in activated sludge plants at EAWAG revealed that the measuring devices remain the weakest point in control applications. To overcome this problem, a software package was developed which analyses and evaluates the residuals between a reference measurement and the sensor and collects the information in a database. The underlying monitoring concept is based on a two-step evaluation of the residuals by means of statistical evaluations using control charts with two different sets of criteria. The first step is a warning phase in which hints on probable errors trigger an increase in the monitoring frequency. In the second step, the alarm phase, the error hypothesis has to be validated and should allow immediate and targeted reactions from the operator. This procedure enables an optimized and flexible monitoring effort combined with an increased probability of early detection of systematic measuring errors. Beside the monitoring concept, information about the measuring device, the performed servicing actions and the responsibilities is stored. Statistical values for the quantitative characterization of the measuring system during operation will be given. They are needed to parameterise controllers or to guarantee the accuracy of the instrument in order to allow reliable calculations of effluent tax. In contrast to other concepts, not only is the measuring device examined under standard conditions, but so is the entire measuring chain from the liquid to be analysed to the value stored in the database of the supervisory system. The knowledge of the response time of the measuring system is then required in order to allow a comparison of the corresponding values.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Quantifying the uncertainty of on-line sensors at WWTPs during field operation(Elsevier, 12/2005) Rieger, Leiv; Thomann, Michael; Gujer, Willi; Siegrist, HansruediIt remains an ongoing task to quantify the uncertainty of continuous measuring systems at WWTPs during field operation. The commonly used methods are based on lab experiments under standardized conditions and are only suitable for characterizing the measuring device itself. For measuring devices under field conditions, a knowledge of the response time, trueness and precision is equally important. A method is proposed which can be used to characterize newly installed on-line sensors or to evaluate monitoring data which may contain systematic errors. The concept is based on comparative measurements between the sensor and a reference. A linear regression is used to differentiate between trueness and precision. Various statistical tests are conducted to validate the preconditions of linear regression. The information about the trueness and precision of the measuring system under field conditions helps to adapt control strategies more effectively to the relevant processes and permits sophisticated control concepts. Moreover, the concept can help to define guidelines for evaluating the uncertainties of effluent quality monitoring to overcome the concerns about on-line sensors, improve the trust in these systems and to allow the use of continuously measuring systems for legislative purposes. The approach is discussed in detail in this paper and all statistical tests and formulas are listed in the Appendix.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Quality evaluation methods for wastewater treatment plant data(IWA Publishing, 2008) Thomann, MichaelNon identified systematic errors in data sets can cause severe problems inducing wrong decisions in function control, process modelling or planning of new treatment infrastructure. In this paper statistical methods are shown to identify systematic errors in full-scale WWTP data sets. With a redundant mass balance approach analyzing five different mass balances, systematic errors of about 10%–20% compared to the input fluxes can be identified at a 5%-significance level. A Shewhart control-chart approach to survey the data quality of on-line-sensors allows a statistical as well as a fast graphical analysis of the measurement process. A 19 month data set indicates that NO3−, PO4− and NH4− on-line analyzers in the filter effluent and MLSS sensors in the aeration tanks were not disturbed by any systematic error for 85–95% of the measuring time. The in-control-interval (±3·standard deviation) has a width of ±12–17% (NO3-N), ±35–40% (PO4-P), ±83% (NH4-N) and ±12–15% (TS) of the measured reference value.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation An efficient monitoring concept with control charts for on-line sensors(IWA Publishing, 2002) Thomann, Michael; Rieger, Leiv; Frommhold, Sabine; Siegrist, Hansruedi; Gujer, WilliA monitoring concept for on-line sensors will be discussed which helps the WWTP staff to detect drift-, shift- and outlier effects as well as unsatisfactory calibration curves. The approach is based on the analysis of comparative measurements between the sensor and a reference method. It combines statistical analysis such as control charts and regression analysis with decision support rules. The combination of two different detection levels in the selected Shewhart control charts with additional criteria allows one to detect ‘out-of-control’ situations early with an optimized measurement effort. Beside the statistical analysis the concept supports the operator with a graphical analysis to monitor the accuracy of on-line measurements efficiently. The widely applicable monitoring concept will be illustrated with examples for an ion-sensitive NH4+- and a MLSS-sensor.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Surface water treatment by UV/H2O2 with subsequent soil aquifer treatment. Impact on micropollutants, dissolved organic matter and biological activity(Royal Society of Chemistry, 2019) Wünsch, Robin; Plattner, Julia; Cayon, David; Eugster, Fabienne; Gebhardt, Jens; Wülser, Richard; von Gunten, Urs; Wintgens, ThomasBecause organic micropollutants (MP) are frequently detected in river waters that are used as drinking water sources, combining a relatively cost-efficient natural treatment with upstream advanced oxidation processes (AOP) appears promising for their efficient abatement. Such a multi-barrier system can be integrated in drinking water production schemes to minimize risks from potentially hazardous MPs. This study investigates the impact of an UV/H2O2 AOP before soil aquifer treatment (SAT) on the abatement of selected MPs (EDTA, acesulfame, iopamidol, iomeprol, metformin, 1H-benzotriazole, iopromide), dissolved organic matter (DOM) (apparent molecular size distribution, specific UV absorbance at 254 nm – SUVA) and microbial parameters (intact cell count, cell-bound ATP). A pilot plant consisting of an AOP (0.5 m3 h−1, 4 mg L−1 H2O2, 6000 J m−2) and two parallel soil columns (filtration velocity: 1 m d−1, column height: 1 m) was continuously operated over a period of 15 months with Rhine river water pre-treated with rapid sand filtration. The investigations revealed a shift towards longer retention times of the humic substances peak in LC analysis of DOM, lower SUVA and higher biodegradability of DOM after UV/H2O2 treatment. In addition, an overall higher abatement of all investigated MPs by the combined treatment was observed (AOP with subsequent SAT) compared to either process alone. This observation could be explained by an addition of the single treatment effects. The strong primary disinfection effect of the AOP was detectable along the first meter of infiltration, but did not lead to any change in the column performance (i.e., similar abatement of dissolved organic matter).01A - Beitrag in wissenschaftlicher Zeitschrift