Universität Stuttgart
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Item Open Access Batch studies of phosphonate and phosphate adsorption on granular ferric hydroxide (GFH) with membrane concentrate and its synthetic replicas(2020) Reinhardt, Tobias; Veizaga Campero, Adriana Noelia; Minke, Ralf; Schönberger, Harald; Rott, EduardPhosphonates are widely used as antiscalants for softening processes in drinking water treatment. To prevent eutrophication and accumulation in the sediment, it is desirable to remove them from the membrane concentrate before they are discharged into receiving water bodies. This study describes batch experiments with synthetic solutions and real membrane concentrate, both in the presence of and absence of granular ferric hydroxide (GFH), to better understand the influence of ions on phosphonate and phosphate adsorption. To this end, experiments were conducted with six different phosphonates, using different molar Ca:phosphonate ratios. The calcium already contained in the GFH plays an essential role in the elimination process, as it can be re-dissolved, and, therefore, increase the molar Ca:phosphonate ratio. (Hydrogen-)carbonate ions had a competitive effect on the adsorption of phosphonates and phosphate, whereas the influence of sulfate and nitrate ions was negligible. Up to pH 8, the presence of CaII had a positive effect on adsorption, probably due to the formation of ternary complexes. At pH > 8, increased removal was observed, with either direct precipitation of Ca:phosphonate complexes or the presence of inorganic precipitates of calcium, magnesium, and phosphate serving as adsorbents for the phosphorus compounds. In addition, the presence of (hydrogen-)carbonate ions resulted in precipitation of CaCO3 and/or dolomite, which also acted as adsorbents for the phosphorus compounds.Item Open Access Impact of combined sewer systems on the quality of urban streams : frequency and duration of elevated micropollutant concentrations(2020) Dittmer, Ulrich; Bachmann-Machnik, Anna; Launay, Marie A.Water quality in urban streams is highly influenced by emissions from WWTP and from sewer systems particularly by overflows from combined systems. During storm events, this causes random fluctuations in discharge and pollutant concentrations over a wide range. The aim of this study is an appraisal of the environmental impact of micropollutant loads emitted from combined sewer systems. For this purpose, high-resolution time series of river concentrations were generated by combining a detailed calibrated model of a sewer system with measured discharge of a small natural river to a virtual urban catchment. This river base flow represents the remains of the natural hydrological system in the urban catchment. River concentrations downstream of the outlets are simulated based on mixing ratios of base flow, WWTP effluent, and CSO discharge. The results show that the standard method of time proportional sampling of rivers does not capture the risk of critical stress on aquatic organisms. The ratio between average and peak concentrations and the duration of elevated concentrations strongly depends on the source and the properties of the particular substance. The design of sampling campaigns and evaluation of data should consider these characteristics and account for their effects.Item Open Access Detoxification of pesticide-containing wastewater with FeIII, activated carbon and Fenton reagent and its control using three standardized bacterial inhibition tests(2017) Rott, Eduard; Pittmann, Timo; Wasielewski, Stephan; Kugele, Amélie; Minke, RalfDischarge of toxic industrial wastewaters into biological wastewater treatment plants may result in inhibition of activated sludge bacteria (ASB). In order to find an appropriate method of detoxification, the wastewater of a pesticide-processing plant in Vietnam was treated with three different methods (FeIII, powdered activated carbon (PAC), Fenton (FeII/H2O2)) analyzing the detoxification effect with the nitrification inhibition test (NIT), respiration inhibition test (RIT) and luminescent bacteria test (LBT). The heterotrophic ASB were much more resistant to the wastewater than the autotrophic nitrificants. The NIT turned out to be more suitable than the RIT since the NIT was less time-consuming and more reliable. In addition, the marine Aliivibrio fischeri were more sensitive than the nitrificants indicating that a lack of inhibition in the very practical and time-efficient LBT correlates with a lack of nitrification inhibition. With 95%, the Fenton method showed the highest efficiency regarding the chemical oxygen demand (COD) removal. Although similar COD removal (60–65%) was found for both the FeIII and the PAC method, the inhibitory effect of the wastewater was reduced much more strongly with PAC. Both the NIT and the LBT showed that the PAC and Fenton methods led to a similar reduction in the inhibitory effect.Item Open Access Influence of ammonium ions, organic load and flow rate on the UV/chlorine AOP applied to effluent of a wastewater treatment plant at pilot scale(2018) Rott, Eduard; Kuch, Bertram; Lange, Claudia; Richter, Philipp; Minke, RalfThis work investigates the influence of ammonium ions and the organic load (chemical oxygen demand (COD)) on the UV/chlorine AOP regarding the maintenance of free available chlorine (FAC) and elimination of 16 emerging contaminants (ECs) from wastewater treatment plant effluent (WWTE) at pilot scale (UV chamber at 0.4 kW). COD inhibited the FAC maintenance in the UV chamber influent at a ratio of 0.16 mg FAC per mg COD (kHOCl–COD = 182 M−1s−1). An increase in ammonium ion concentration led to a stoichiometric decrease of the FAC concentration in the UV chamber influent. Especially in cold seasons due to insufficient nitrification, the ammonium ion concentration in WWTE can become so high that it becomes impossible to achieve sufficiently high FAC concentrations in the UV chamber influent. For all ECs, the elimination effect by the UV/combined Cl2 AOP (UV/CC) was not significantly higher than that by sole UV treatment. Accordingly, the UV/chlorine AOP is very sensitive and loses its effectiveness drastically as soon as there is no FAC but only CC in the UV chamber influent. Therefore, within the electrical energy consumption range tested (0.13–1 kWh/m3), a stable EC elimination performance of the UV/chlorine AOP cannot be maintained throughout the year.Item Open Access Entwicklung und Validierung eines CSB-basierten und temperatursensitiven Bemessungsansatzes für Tropfkörper : Untersuchungen an technischen und halbtechnischen Tropfkörpern in warmen Klimazonen(Stuttgart : Institut für Siedlungswasserbau, Wassergüte- und Abfallwirtschaft der Universität Stuttgart ISWA, 2020) Seeger, Michael; Steinmetz, Heidrun (Prof.-Dr.-Ing.)Untersuchungen an technischen und halbtechnischen Tropfkörperanlagen in warmen Klimazonen zur Evaluierung des Temperatureinflusses auf die Kohlenstoffelimination und Nitrifikation. Entwicklung, Kalibrierung und Validierung eines CSB-basierten und temperatursensitiven Bemessungsansatzes für Tropfkörper, basierend auf den gewonnenen Betriebsdaten sowie Literaturwerten. Zudem flankierende (halbtechnische) Untersuchungen zum Einfluss konstant erhöhter Salzgehalte (bis 10 g/l NaCl) auf die Kohlenstoffelimination im Tropfkörper.Item Open Access Kombination aus Biowäscher- und Biomembranverfahren zur Reinigung von Abluft und hydrophilen und hydrophoben Inhaltsstoffen(1994) Reiser, Martin; Fischer, Klaus; Engesser, Karl-HeinrichAbluft, die eine Mischung aus wasserlöslichen uod wasserunlöslichen organischen Lösungsmitteln enthält, stellt für ein biologisches Reinigungsverfahren eine große Herausforderung dar. Durch Kombination eines Biomembranreaktors mit Silikonkautschukmembranen und einem Biowäscher konnten für ein Gemisch von Methanol, n-Hexan und Toluol in der Abluft gute Reinigungsleistungen erzielt werden.Item Open Access Einsatz von Gensonden zur Identifikation von Mikroorganismen im belebten Schlamm(1994) Engesser, Karl-Heinrich; Schmid, AndreasDie Gensondentechnik stellt heute schon einen extrem leistungsfähigen, neuartigen Ansatz zur Populationsanalyse komplexer Ökosysteme und damit auch der Charakterisierung der "Biomasse" des Belebtschlammes dar. Für die Gensondentechnik typisch ist ein relativ geringer Zeitaufwand bei der Durchführung. Dies ermöglicht erstmals die Analyse der Dynamik einer Population nahezu in Echtzeit.Item Open Access Recycling of coffee by-products by composting in context of climate-relevant emissions and products(Stuttgart : FEI e.V. Eigenverlag, 2023) San Martin Ruiz, Macarena; Kranert, Martin (Prof. Dr.-Ing.)Coffee has become one of the most popular beverages and provides a livelihood for millions of people around the world. Coffee is one of Costa Rica's most important and emblematic exports (about one and a half million bags per year) and is closely linked to the country's national identity. However, climate change poses a challenge to the livelihoods of Costa Rican coffee farmers and the long-term viability of the crop. Thus, the environmental impact of coffee production must also be reduced and made more sustainable. Therefore, it is necessary to treat the residues from coffee production as climate-neutral and resource-saving as possible in the sense of a circular economy. This is of particular importance, not least because the consumption of coffee has increased worldwide. Agriculture and waste management are disconnected from each other worldwide. This leads to permanent nutrient depletion of soils and high greenhouse gas (GHG) emissions due to insufficient or excessive use of fertilizers. Coffee by-products, especially coffee pulp, are usually considered waste on coffee plantations and are mostly discarded or disposed of in rivers. In some cases, composting of residues also takes place, which usually results in high emissions due to improper rotting processes. In the context of global warming, inadequate composting and mineral fertilization contribute to greenhouse gas emissions. Composting emits greenhouse gases such as methane from the decomposition of organic material and carbon dioxide from fossil fuels from the equipment required to turn and process the waste. Fertilization of coffee plants, on the other hand, emits greenhouse gases such as nitrous oxide from the soil, especially when nitrogen fertilizers are used. This leads to serious consequences for the climate and the environment. The purpose of the present thesis was to investigate which methane emissions occur with the current treatment method of the residues and how an optimized composting process can significantly reduce these emissions and at the same time produce an organic fertilizer. In addition, nitrous oxide emissions from the use of composts compared to mineral fertilizers on coffee plantations should be investigated. This should contribute to making coffee production more sustainable.Item Open Access Dosage concentration and pulsing frequency affect the degradation efficiency in simulated bacterial polycyclic aromatic hydrocarbon-degrading cultures(2023) Vogel, Anjela L.; Thompson, Katharine J.; Kleindienst, Sara; Zarfl, ChristianeA major source of anthropogenic polycyclic aromatic hydrocarbon (PAH) inputs into marine environments are diffuse emissions which result in low PAH concentrations in the ocean water, posing a potential threat for the affected ecosystems. However, the remediation of low-dosage PAH contaminations through microbial processes remains largely unknown. Here, we developed a process-based numerical model to simulate batch cultures receiving repeated low-dosage naphthalene pulses compared to the conventionally used one-time high-dosage. Pulsing frequency as well as dosage concentration had a large impact on the degradation efficiency. After 10 days, 99.7%, 97.2%, 86.6%, or 83.5% of the 145 mg L −1 naphthalene was degraded when given as a one-time high-dosage or in 2, 5, or 10 repeated low-concentration dosages equally spaced throughout the experiment, respectively. If the simulation was altered, giving the system that received 10 pulses time to recover to 99.7%, pulsing patterns affected the degradation of naphthalene. When pulsing 10 days at once per day, naphthalene accumulated following each pulse and if the degradation was allowed to continue until the recovered state was reached, the incubation time was prolonged to 17 days with a generation time of 3.81 days. If a full recovery was conditional before the next pulse was added, the scenario elongated to 55 days and generation time increased to 14.15 days. This indicates that dissolution kinetics dominate biodegradation kinetics, and the biomass concentration of PAH-degrading bacteria alone is not a sufficient indicator for quantifying active biodegradation. Applying those findings to the environment, a one-time input of a high dosage is potentially degraded faster than repeated low-dosage PAH pollution and repeated low-dosage input could lead to PAH accumulation in vulnerable pristine environments. Further research on the overlooked field of chronic low-dosage PAH contamination is necessary.Item Open Access Emission von Pilzsporen in Müllverarbeitungsanlagen(1994) Göttlich, Elke; Engesser, Karl-Heinrich; Bardtke, DieterDie Häufigkeit und Sporendichte verschiedener Pilzarten in der Luft von Kompostwerken, bei der Sortierung, Müllverbrennung und auf Deponien wurden in einer Studie in 11 Betrieben untersucht. Außer A. fumigatus, über dessen klinische und allergologische Bedeutung die meisten Kenntnisse vorliegen, wurden verschiedene Pilzarten, die als potentiell gesundheitlich relevant angesehen werden,in Keimdichten über den derzeitigen Orientierungswerten für Pilzbelastungen der Luft nachgewiesen. Obwohl vergleichbare Daten zumeist fehlen und daher gesicherte Richtgrenzwerte gegenwärtig nicht festgelegt werden können, sind die gesundheitlichen Risiken der Beschäftigten an den Arbeitsplätzen als erheblich anzusehen.