02 Fakultät Bau- und Umweltingenieurwissenschaften
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3
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Item Open Access Optimal design of experiments to improve the characterisation of atrazine degradation pathways in soil(2021) Chavez Rodriguez, Luciana; González‐Nicolás, Ana; Ingalls, Brian; Streck, Thilo; Nowak, Wolfgang; Xiao, Sinan; Pagel, HolgerContamination of soils with pesticides and their metabolites is a global environmental threat. Deciphering the complex process chains involved in pesticide degradation is a prerequisite for finding effective solution strategies. This study applies prospective optimal design (OD) of experiments to identify laboratory sampling strategies that allow model‐based discrimination of atrazine (AT) degradation pathways. We simulated virtual AT degradation experiments with a first‐order model that reflects a simple reaction chain of complete AT degradation. We added a set of Monod‐based model variants that consider more complex AT degradation pathways. Then, we applied an extended constraint‐based parameter search algorithm that produces Monte‐Carlo ensembles of realistic model outputs, in line with published experimental data. Differences between‐model ensembles were quantified with Bayesian model analysis using an energy distance metric. AT degradation pathways following first‐order reaction chains could be clearly distinguished from those predicted with Monod‐based models. As expected, including measurements of specific bacterial guilds improved model discrimination further. However, experimental designs considering measurements of AT metabolites were most informative, highlighting that environmental fate studies should prioritise measuring metabolites for elucidating active AT degradation pathways in soils. Our results suggest that applying model‐based prospective OD will maximise knowledge gains on soil systems from laboratory and field experiments.Item Open Access Hydrologische und hydraulische Entwurfsgrundlagen und Bemessungsrichtlinien : Vorwort zum Sonderheft(1988) Kobus, HelmutAm 21. Juli 1987 fand an der Universität Stuttgart eine Vortragsveranstaltung statt, die sich mit den hydrologischen und hydraulischen Aspekten der Sicherheit von Stauanlagen befaßte. Das Sonderheft der WASSERWIRTSCHAFT enthält die Beiträge dieser Veranstaltung, welche vom Ministerium für Umwelt Baden-Württemberg gemeinsam mit dem Institut für Wasserbau der Universität Stuttgart ausgerichtet und vom Lehrstuhl für Technische Hydromechanik und Wasserbauliches Versuchswesen organisatorisch betreut wurde.Item Open Access Sustainability assessment of fuel cell buses in public transport(2018) Lozanovski, Aleksandar; Whitehouse, Nicole; Ko, Nathanael; Whitehouse, SimonHydrogen fuel cell (H2FC) buses operating in every day public transport services around Europe are assessed for their sustainability against environmental, economic and social criteria. As part of this assessment the buses are evaluated against diesel buses both in terms of sustainability and in terms of meeting real world requirements with respect to operational performance. The study concludes that H2FC buses meet operability and performance criteria and are sustainable environmentally when ‘green’ hydrogen is used. The economic sustainability of the buses, in terms of affordability, achieves parity with their fossil fuel equivalent by 2030 when the indirect costs to human health and climate change are included. Societal acceptance by those who worked with and used the buses supports the positive findings of earlier studies, although satisfactory operability and performance are shown to be essential to positive attitudes. Influential policy makers expressed positive sentiments only if ‘green’ hydrogen is used and the affordability issues can be addressed. No “show-stopper” is identified that would prevent future generations from using H2FC buses in public transport on a broad scale due to damage to the environment or to other factors that impinge on quality of life.Item Open Access Statistical analysis of climate trends and impacts on groundwater sustainability in the Lower Indus Basin(2024) Ahmed, Waqas; Ahmed, Suhail; Punthakey, Jehangir F.; Dars, Ghulam Hussain; Ejaz, Muhammad Shafqat; Qureshi, Abdul Latif; Mitchell, MichaelAgricultural intensification is increasing global demand for water, with groundwater especially susceptible given its year-round reliability. Climate change impacts on groundwater recharge exacerbate uncertainties for future access and use, especially for large aquifers across alluvial plains such as the Indus Basin of Pakistan. To generate better understanding of climate change impacts on groundwater balances in such contexts, we used MODFLOW 2005 to quantify the groundwater budget of the Northern Rohri Canal Command Area under RCP 4.5 and 8.5 climatic scenarios, while also taking climatic regionalisation into account. Under a baseline scenario, total annual pumping in the northern Rohri command was estimated to be 3.619 billion cubic metres (BCM), and the total net loss in storage over the simulation period from October 2010 to April 2014 was estimated at 1.244 BCM per year. By 2047, net decline in storage is projected to more than double to 2.185 per year under RCP 4.5 scenario and 2.214 under RCP 8.5. Our estimates suggest that a sustainable yield across the command area should be managed at approximately 3 ± 0.3 BCM per year to ensure sufficient adaptive reserves of groundwater for access during times of drought and inadequate surface supply, while also reducing waterlogging impacts from high watertables. This first-time estimate of sustainable yield provides irrigation system managers with an overall guide from which divisional-scale measures to achieve the goal can be identified through stakeholder engagement.Item Open Access Enhanced composting as a way to a climate-friendly management of coffee by-products(2020) San Martin Ruiz, Macarena; Reiser, Martin; Kranert, MartinThis study investigated the performance of aerobic windrow systems by using coffee by-products and green waste to reduce gaseous emissions. Thereafter, a comparison with the current treatment and gaseous emissions at a Coffee Mill in Costa Rica was made. Two different studies where performed in Germany (pile I and II) and one study in a Coffee Mill in Costa Rica (pile III). Temperature, water content, and pH were the key parameters controlled over 35 days in all the systems. Moreover, CH4 emission rates were quantified by a FTIR and by a portable gas detector device where the emissions reached values 100 times higher when coffee by-products as a unique material for the composting process was used. Results show that highest emission rates during the composting process for pile I was 0.007 g(m2)-1 h-1, for pile II 0.006 g(m2)-1 h-1, and for pile III 3.1 g(m2)-1 h-1. It was found that CH4 emissions could be avoided if the mixture and the formation of the windrow piles were performed following the key parameter for composting, and the usage of additional material is used. With this, the reduction of CH4 emissions at the Mill in Costa Rica could be achieved in the future.Item Open Access Design for and from disassembly with timber elements : strategies based on two case studies from Switzerland(2023) Grüter, Cäsar; Gordon, Matthew; Muster, Marcel; Kastner, Fabian; Grönquist, Philippe; Frangi, Andrea; Langenberg, Silke; Wolf, Catherine deWhen a timber building gets disassembled and its elements either are burned or biodegrade, the carbon stored in the timber structure gets released to the atmosphere as CO2. Reusing timber elements prevents this process from happening and thus delays the global warming caused by greenhouse gas emissions. Even if there is a long historic tradition of timber reuse in Switzerland, currently a low fraction of a timber building’s elements is being reused after its disassembly. In this study, strategies that could facilitate circular use of timber elements are analyzed. The focus lies on the design process, which is investigated from two perspectives: strategies at the start-of-life of buildings to enable new timber element cycles to emerge (design for disassembly, or DforD), and strategies at the end-of-life of buildings to keep existing timber elements cycles closed (design from disassembly, or DfromD). Two case studies of recently completed multi-story timber-hybrid buildings in Switzerland were analyzed from both perspectives. Regarding DforD, a scoring system was developed that assesses single elements according to their disassembly and reuse potential. Regarding DfromD, a building design optimization tool was created that takes dimensional design tolerances of a building as an input and proposes a procurement-optimized and structurally safe arrangement of reused elements, which are taken from an inventory that is based on the two case studies. It was found that connections between reinforced concrete and timber parts play a crucial role in terms of DforD and that building layouts with DfromD elements may vary widely according to the chosen optimization variable. In conclusion, both applications have the potential to scale up the competitiveness of reused elements.Item Open Access Advanced methods to investigate hydro‐morphological processes in open‐water environments(2021) Haun, Stefan; Dietrich, StephanHydro‐morphology describes the interactions between water and sediments in fluvial systems and the corresponding processes across all spatial and temporal scales. The results are natural and anthropogenically influenced bed structures and fluvial landforms. However, many of these hydro‐morphological processes cannot be described analytically yet, as a result of their stochastic behaviour and the multitude of processes involved across spatial and temporal scales. Deeper knowledge of these processes is essential, not only for understanding the system itself, but also for practical applications, which rely on correct and reliable investigations of these processes. During the European Geoscience Union (EGU) General Assembly (GA) 2018 in Vienna, Austria, the conveners of the session on “Measurements, monitoring and numerical modelling of sedimentary and hydro‐morphological processes in open‐water environments” had the idea of initiating a special issue, containing a collection of recent achievements in this research field. The aim of this extended introduction is twofold. First, an overview on research needs in investigating hydro‐morphological processes in open‐water environments is given in this article. Second, recently published studies that aim to improve the understanding of hydro‐morphological processes in rivers, lakes and reservoirs by innovative measurement approaches are discussed. In addition to submitted papers collected from the EGU GA in 2017, 2018 and 2019, related studies published in Earth Surface Processes and Landforms (ESPL) over the last two years are also incorporated into this special issue. The papers selected cover a wide range of studies with differing spatial and temporal resolutions. This broad spectrum of different scales clearly indicates the challenges associated with the development and use of advanced methods for investigating hydro‐morphological processes in open‐water environments.Item Open Access Biological waste air and waste gas treatment : overview, challenges, operational efficiency, and current trends(2020) Dobslaw, Daniel; Ortlinghaus, OliverInternational contracts to restrict emissions of climate-relevant gases, and thus global warming, also require a critical reconsideration of technologies for treating municipal, commercial, industrial, and agricultural waste gas emissions. A change from energy- and resource-intensive technologies, such as thermal post-combustion and adsorption, as well to low-emission technologies with high energy and resource efficiency, becomes mandatory. Biological processes already meet these requirements, but show restrictions in case of treatment of complex volatile organic compound (VOC) mixtures and space demand. Innovative approaches combining advanced oxidation and biofiltration processes seem to be a solution. In this review, biological processes, both as stand-alone technology and in combination with advanced oxidation processes, were critically evaluated in regard to technical, economical, and climate policy aspects, as well as present limitations and corresponding solutions to overcome these restrictions.Item Open Access Ein Beitrag zur Bemessung der engeren Schutzzone in Porengrundwasserleitern(1980) Spitz, Karlheinz; Mehlhorn, Hans; Kobus, HelmutEine wichtige wasserwirtschaftliche Aufgabe zur Sicherung der Grundwasservorkommen als Trinkwasserreserven besteht in der Ausweisung von Wasserschutzgebieten. Die Begrenzung der engeren Schutzzone wird hierbei durch eine vorgegebene Mindestverweilzeit (in der Regel 50 Tage) festgelegt. Es wird ein einfaches analytisches Berechnungsverfahren vorgestellt, das die Ermittlung der 50-Tage-Linie für den Einzelbrunnen in einem Grundwasserstrom exakt und ohne mathematische Vereinfachungen ermöglicht. Zudem wird erstmals der Einfluß von Vermischungseffekten quantitativ berücksichtigt. Die vorgestellte Methodik läßt sich auf beliebige Strömungskonfigurationen wie Brunnengruppen oder Uferfiltrationsbrunnen erweitern.Item Open Access Beeinflussung von Grundwassertemperaturen durch Wärmepumpen(1980) Kobus, Helmut; Mehlhorn, HansGrundwasserbetriebene Wärmepumpen sind energiewirtschaftlich zwar wünschenswert, doch steht ihrem verstärkten Einsatz derzeit noch entgegen, daß über die Auswirkungen solcher Anlagen auf das Grundwasser bisher nur sehr wenig bekannt ist. Im vorliegenden Beitrag werden zunächst die Grundlagen der Wärme- und Schadstoffausbreitung in Grundwasserleitern behandelt und die Transportmechanismen Konvektion, Dispersion und Wärmeleitung erläutert. Für einfache Strömungsfälle werden quasi-stationäre Lösungen zur Abschätzung der langfristig zu erwartenden Temperaturanomalie vorgestellt. Die Bedeutung von dispersiven Vermischungseffekten sowie von Schichtungseffekten zufolge temperaturbedingter Dichteunterschiede wird ebenfalls diskutiert. Damit liefert der Aufsatz einen ersten Beitrag zur Quantifizierung der Umweltauswirkungen von Wärmepumpen.