Freshwater lakes represent a major natural source of methane to the atmosphere, a potent greenhouse gas with critical climatic implications. Particularly in stratified lakes methane can potentially build up to high concentrations in the anoxic hypolimnion and be emitted by a variety of flux mechanisms. Microbial methane oxidation, which is principally mediated by anaerobic archaea and aerobic proteobacteria, is the only process impeding methane emissions from lacustrine waters. The majority of occurring methane oxidation in lakes has been ascribed to aerobic methanotrophs, which are preferably located at oxic/anoxic interfaces in both sediments and water columns. However, there is increasing evidence that methane is also oxidized in anoxic hypolimnia of lakes, where oxygen is not available as an oxidizing agent. It is speculated that electron acceptors such as nitrate, nitrite and iron- or manganese oxides could be of relevance there. Though the microorganisms mediating these processes remain elusive, recent laboratory studies revealed novel methanotrophs and pathways for methane oxidation, which could also be essential in lakes. [...]<br /><br /> Methan ist ein starkes Treibhausgas und hoch relevant für Klimafragen. Wichtige Quellen des natürlichen Ausstosses von Methan in die Atmosphäre sind Süsswasserseen. Besonders in geschichteten Seen können hohe Konzentrationen von Methan im anoxischen Hypolimnion akkumuliert und auf verschiedenste Weise emittiert werden. Einzig durch mikrobielle Methanoxidation, welche prinzipiell durch anaerobe Archeaen und aerobe Proteobakterien durchgeführt wird, kann der Ausstoss von Methan aus Seen unterbunden werden. Der Hauptteil der mikrobiellen Methanoxidation wird aeroben methanotrophen Bakterien zugeschrieben, welche sich vorzugsweise in oxisch/anoxischen Grenzschichten von Sedimenten oder Wassersäulen aufhalten. Zunehmend gibt es jedoch Hinweise, dass Methan auch im anoxischen Hypolimnion oxidiert wird, also ohne Verfügbarkeit von Sauerstoff als Oxidationsmittel. Stattdessen könnten unter diesen Bedingungen alternative Elektronenakzeptoren, wie Nitrat, Nitrit und Eisen- oder Manganoxide eine Rolle spielen. Bislang konnte nicht geklärt werden, welche Mikroorganismen diese Prozesse steuern, jedoch wurden kürzlich in Laborstudien neue methanotrophe Mikroorganismen entdeckt, welche ebenfalls eine wichtige Rolle in Seen spielen könnten. [...]

One of the core areas of ecological research is to understand species distributions across spatial and environmental gradients. Environmental change can affect spatially structured species distributions and modify ecosystem functioning. Many ecosystem functions, such as biomass production and the decomposition of organic material, are driven by microbes, which are the most abundant organisms on our planet, and essential drivers of ecosystem functions. While being so important for live on earth, we still know very little about the factors governing microbial diversity. One reason for this is that high resolution molecular methods, which allow for describing microbial diversity and community composition, have only been developed within the last few decades. However, even modern sequencing methods still have drawbacks and limitations and there is still no standard method for analyzing microbial communities. [...]<br /><br />Die Untersuchung, wie sehr sowohl biogeographische Gradienten, als auch Umweltveränderungen die Ausbreitung und räumliche Verteilung von Organismen beeinflussen, ist ein Kerngebiet der ökologischen Forschung. Umweltveränderungen können sich auf die räumliche Struktur der Verteilung von Organismen auswirken und so auch Ökosystemfunktionen verändern. Kleinstlebewesen (Mikroorganismen) sind nicht nur die häufigsten Lebewesen auf unserem Planeten, sondern auch verantwortlich für viele Ökosystemfunktionen, wie zum Beispiel den Auf- und Abbau von organischem Material. Obwohl das Leben auf unserer Erde ohne Mikroorganismen nicht möglich wäre, wissen wir immer noch sehr wenig darüber, welche Faktoren ihre Vielfalt beeinflussen. Ein Grund dafür ist, dass hochauflösenden molekulare Methoden, welche es uns erlauben, mikrobielle Diversität besser zu untersuchen, erst in den letzten Jahrzehnten entwickelt worden sind. Doch auch hochmoderne molekulare Sequenziermethoden haben noch immer ihre Nachteile und Grenzen, und so gibt es bisher noch keine Standardmethode für die Untersuchung von mikrobiellen Gemeinschaften. [...]

Each year, around 2 million children younger than five years die due to acute respiratory infections and diarrhoeal diseases. The two diseases are not only the global leading causes of under-five mortality but also major killers in humanitarian disasters. Handwashing with soap at key times is the best preventive measure against diarrheal diseases and an effective barrier to acute respiratory infections. In developing countries, where the death tolls are highest, regular handwashing is rarely habitual. Accordingly, promotion of handwashing should be a priority in development and emergency programs. There is a need and a demand for effective handwashing interventions but rigorous evaluations of handwashing interventions in development and emergency aid are scarce. Evaluation of handwashing interventions are challenging due to the lack of a valid behaviour measure which is at the same time efficiently collected. Consequently, the effectiveness of regularly applied handwashing interventions is uncertain and evidence-based programming an exception. Behaviour change interventions are assumed to be especially effective when they are theory-based, i.e. when they address and thus modify the social-cognitive determinants of a behaviour and consequently change the behaviour itself. [...]

Hydrological or drainage models can be valuable tools to support water management in urban environments. They can help to assess the characteristics of a catchment and to make predictions about its response (e.g. discharge). Unfortunately, parameters and results of these models are not perfect. These inaccuracies manifest themselves as model discrepancy, the so-called bias. Model bias represents the systematic deviation between model output and the real system response. There are two main causes of bias. First, there are errors in the input estimates, e.g. due to the insufficient coverage of pluviometers. Second, there are deficits in the model structure, e.g. due to the use of oversimplified empirical equations. Besides model bias, there are output measurement errors, e.g. due to imprecise flowmeters.<br />Until now, a large proportion of hydrological studies implicitly neglected input and structural errors. Neglecting these can lead to: i) misrepresented output measurement errors, ii) incorrect parameter estimates which compensate for model discrepancy, and iii) predictions which underestimate the uncertainty. Furthermore, these approaches do not provide guidance for finding the reasons for bias. Therefore, they cannot support its reduction. This inappropriate error consideration can finally lead to faulty risk assessment, flawed evaluation of decision alternatives, and, consequently, impaired urban water management. More advanced error assessment techniques are therefore called for.<br />The main goal of this thesis is to better represent input, structural, and output measurement errors. This can meliorate parameter estimation and prediction generation. The main thesis contributions are two. The first is a realistic description of the uncertainties in stormwater, wastewater, and sediment transport predictions. The second is a sound representation of errors in the rainfall inputs. Additionally, we discuss and compare different statistical methods used for hydrological inference. Finally, we also present a new tool to improve sewer flow monitoring. [...]

The interplay of natural selection and gene flow is a debate that keeps evolutionary biologists busy for years. A whole body of literature deals with it, and especially the study of lake-stream divergence in freshwater ecosystems helped to get insight into these complex interactions. However, we argue that there is a gap in the understanding of divergence between lakes and streams in metapopulations. Therefore, we studied several lake and stream populations of Cottus gobio in the Lake Lucerne drainage system. We were able to show parallel phenotypic differentiation between lake and stream populations. Additionally microsatellite analyses showed that lake-stream transitions are a significant barrier to gene flow. We conclude that natural selection reduces gene flow between populations of contrasting habitats.

A plethora of natural and synthetic chemicals are produced and consumed worldwide. Once those chemicals are consumed and enter the environment, they can reach natural water systems via waste water treatment plant effluents, agricultural run off or other input sources. In case these contaminants are stable enough, they can potentially reach lakes and sorb to sediments. Pollutants which persist over time in the sediment can serve as indicators of past applications and sometimes reveal input patterns. Since the development and establishment of liquid chromatography- high resolution mass spectrometry (LC-HRMS), the analysis of polar organic pollutants was simplified, even for more complex matrices like sediments. Recently, new strategies like the application of target analysis combined with suspect screening and non-target screening are being used to exploit the cocktail of substances present today. Additionally, the risk for organisms exposed to those chemicals can help to understand the individual effects they inherit. Target and suspect screening analysis was conducted at 5 different sampling points, resulting in the detection of 39 target compounds, including 4 transformation products, 16 plant protection products, 7 biocides and 1 corrosion inhibitor, all detected in the<em> pg\g_dw</em> to <em>ng\g_dw</em> range. Temporal and spatial patterns for the last few decades of pesticides and their metabolites within the catchment of Lake Greifensee was determined for all detected compounds. Diuron and its transformation product diuron-desmethyl showed an almost identical temporal trend across the sediment core. Further, spatial trends across the lake showed a distinct decrease of concentrations for climbazole and<br /> 4-&amp;5-methylbenzotriazole, when looking at the top three sediment layers. Temporal and spatial concentration trends of the detected contaminants were linked to their application within the catchment, resulting in explanations for their presence at different locations. Based on these results, a risk assessment was performed using chronic water quality criteria data converted into sediment quality criteria using partition coefficient between organic carbon in the sediment and water as well as the corresponding sediment concentrations of single substances, which led to a risk quotient. The highest RQs were obtained for irgarol, while the remaining compounds show RQs from 0.02 up to approximately 5. The mixture toxicity showed an insufficient to poor evaluation even when excluding the major contributor irgarol from the calculation. Overall, this work showed that temporal and spatial concentration patterns of pesticides within a sediment core can be linked to the applications in the associated catchment. Further, a rough risk assessment was derived for the detected pesticides which showed a relevant risk evaluation for several single substances and the mixture toxicity of sediment layers.

Der einstufige Nitritations/Anammox-Prozess hat sich in den vergangenen Jahren als effektive Methode zur biologischen Behandlung ammoniumreicher Abwässer etabliert. Aufgrund seiner ökologischen und ökonomischen Vorteile gegenüber der Nitrifikation mit anschließender Denitrifikation leistet er bereits heute einen wertvollen Beitrag zur qualitativen Verbesserung unserer Gewässer.<br /> Eine der größten Herausforderungen beim Betrieb des Verfahrens besteht darin, die Population Nitrit oxidierender Bakterien im Reaktor möglichst gering zu halten. Diese konkurrieren mit den Anammoxbakterien um Nitrit und sind daher in der Lage die Entstickungsleistung des Prozesses maßgeblich zu verringern. Mittlerweile ist bekannt, dass Nitritoxidierer genetisch dazu befähigt sind Enzyme zu produzieren, welche für den Abbau niedermolekularer, leicht abbaubarer organischer Kohlenstoffverbindungen notwendig sind. Ob sich diese Fähigkeit auf die praktische Anwendung des Verfahrens auswirkt, ist derzeit jedoch nicht bekannt. [...]<br /><br /> In recent years the nitritation/anammox-process has proven to be one of the most viable strategies for biological treatment of high strength wastewaters. An important contribution to the purification of receiving water bodies has been made by using this novel approach. The process has also shown to be more sustainable and cost effective compared to conventional nitrification with subsequent denitrification.<br /> One of the most important drawback of this technique is the confinement of nitrite oxidizing bacteria in the reactor. These bacteria compete with anammox bacteria for nitrite and are therefore able to reduce the nitrogen removal rate significantly. While it is known that nitrite oxidizers are genetically capable to produce enzymes involved in the degradation of low molecular organic carbon compounds, it remains unknown whether this ability could negatively affect the process performance. [...]

Despite concerted efforts, Nepal continues to suffer from an underdeveloped water supply infrastructure. Low piped-water supply coverage especially in rural areas have been motivating an increasing number of water provision projects. However, the concern about water quality is very low, especially concerning the microbial water quality, that is related to waterborne disease like diarrhea. A few studies on microbial water quality were performed in Nepal, however, most of them are limited to urban areas.<br /> The main objective of the joint research project of the Swiss Federal Institute of Aquatic Science and Technology (EAWAG) and HELVETAS Swiss Intercooperation (HELVETAS) was to assess the microbial water quality, household water management practices, and opportunities for market-based interventions in remote rural areas in Western Nepal. This shall provide the systematic microbiological data, behavioral, and economic understanding required to design an action plan that can improve the drinking water quality at the household level. [...]

The <em>Blue Diversion Toilet </em>(BDT) was developed as a possible answer to the sanita-tion crisis in urban slums. It is a urine-diverting dry toilet with an integrated water cycle that provides water for handwashing, personal hygiene and flushing the urine bowl. The recovery of the water happens in a so called water wall, based on a biolog-ically activated membrane bioreactor (BAMBi) together with an electrolysis module as the post-treatment. In order to primarily minimize the costs and the energy de-mand of the toilet, granular activated carbon (GAC) filters were investigated as an alternative to the electrolysis. For this purpose, four water walls with different post-treatments were monitored and compared: a control without any treatment, one drained and one flooded GAC bed and an electrolysis module. This study focused on the produced water quality from a hygienic point of view as well as with regard to the aesthetic, namely the colour. In order to investigate the possibility of the presence of pathogens in the recycled water, faecal indicators (<em>E. coli </em>and total coliforms) were monitored. Moreover, surrogates for organic content and therefore, the potential for microbial growth were investigated by measuring the amount of total organic carbon (TOC) and assimilable organic carbon (AOC). Further, a spiking experiment with a viral indicator (MS2) was conducted in order to examine the retention of vi-ruses within the water wall. Finally, the absorbance of the water was measured in order to investigate the colour removal. It was found that with both applications, GAC and electrolysis, the absence of <em>E. coli </em>in the effluent in most of the times was guaranteed and thus the risk of bacterial pathogens could be most probably excluded. While drained GAC and flooded GAC yielded to a significant TOC removal, no sig-nificant TOC removal by the electrolysis was observed. Further, no significant AOC removal by the post-treatments could be measured; neither for the electrolysis nor for GAC. All median AOC concentrations in the effluents exceeded the proposed limits for a biological stability at least for drinking water. In order to draw reliable conclu-sions of the impact of the post-treatments on the removal of viruses, further research is needed. With regard to the aesthetic, both, electrolysis and GAC, yielded to a sig-nificant reduction of absorbance of the water and did not significantly differ in their ability to reduce the colour. From those results it can be concluded that at the current settings of the electrolysis, GAC constitutes a feasible alternative. Due to the fact that both, electrolysis and GAC alone, only partly achieved a satisfying water quality, the combination of both should be considered, since this could achieve a better water quality and save energy.

The hydraulic behavior and the capacity of sewer systems are assessed through hydrodynamic modeling. They are widely used in drainage planning, although their parameters are mostly estimated and the models are only checked for general plausibility. The Master‘s Thesis assessed the effect of calibration on the model reliability on the basis of a case study, namely Fehraltorf.<br /> Fehraltorf is located in the agglomeration of Zurich and Winterthur and is inhabited by 6’292 people. Most of the village of Russikon and Fehraltorf are connected to the WWTP of Fehraltorf. The DWF amounts up to 66 l/s, whereas the residual flow Q347 of the main receiving water (Luppmen) is 72 l/s. The infiltration of the groundwater is 30.1 l/s, as a significant share of the drainage system was built below the average groundwater table.<br /> During the thesis the conversion of the Mike Urban model to SWMM was revised and further adjustments were implemented. The data for input and calibration was chosen depending on its reliability and further processed if necessary. Rain events were selected and split for calibration and validation. Parameters known to be changed in the calibrations were selected and in the sensitivity analysis the most sensitive, and thus, important parameters were determined. Then, the calibration was conducted manually as well as automatically with simulated annealing. The effect of calibration was assessed for the calibration and validation events visually and with various objective functions, viz. Nash-Sutcliffe Efficiency, total volume, peak flow and time to peak. The hydraulic performance of the sewer system was tested by simulating a 10-year design rainfall event in the uncalibrated and the calibrated model.<br /> For the simulations, the data of the rain gauge on the WWTP had to be discarded because it showed high deviations to the ones installed by EAWAG. The rainfall data and flow data (of the FloDars) collected by EAWAG were assessed to be reliable, but as the measurements were installed recently, only four rain events were available for calibration and validation. The objective functions could be raised to a satisfying level in the manual calibration and were further improved in the automatic calibration. The validation confirmed that the reliability of the model could be increased with calibration. Furthermore, the assessment of the sewer system revealed that there are less capacity limits in the calibrated model then in the uncalibrated one, but further adjustments are needed due to numerical instabilities.<br /> Even though the validation suggests that manual as well as automatic calibration enhance the reliability of the model because of improved goodness of fit assessed by different objective functions, further input data and reliable calibration data is needed to perform the calibration once more.<br /> After all, calibration is strongly recommended by the author of this thesis to not only improve parameter values which were only estimated in the uncalibrated models but also to detect systematic errors in the data and the model structure.

Many organic substances enter our environment, either intact or as transformation product, after their application as pharmaceuticals, personal care products, pesticides, biocides or industrial chemicals. Due to annually increasing production rates od these chemicals, there is a need for detailed monitoring. Besides target screening, the addition of new detection techniques, like suspect and nontarget screening, are becoming increasingly important to pay attention to all contaminants. Sediments cores provide historic records of many organic contaminants, but their use was limited to legacy compounds due to the very complex matrix. [...]

Fresh water sources are getting scarcer and innovative technologies are necessary to treat other water sources, for example wastewater. Forward Osmosis (FO) has been met with increasing interest over the past decades as it shows different advantages over pressure driven membrane processes. One advantage is a lower fouling propensity that gives FO high potential in treating feed waters with high fouling capacity. Literature on biofouling in FO is sparse. The objective of this thesis was therefore to investigate the e ect of feed spacers on biofouling in a FO system.<br /><em>Pseudomonas aerigunosa</em> was used as a model strain to biofoul a closed-loop custom-made flow system with a polyamide thin-film composite FO membrane. Synthetic wastewater mimicking secondary effluent was circulated as the feed solution, while 0.5M sodium chloride solution was used on the draw side to generate an initial flux of 20L/m²/h. Baselines were recorded over 24h to account for dilution, followed by the biofouling run lasting again 24h. After the biofouling membrane and feed spacer were analyzed for bacterial concentration via plate counts, for total organic carbon and protein and with confocal laser scanning microscopy for further characterization of the biofilm.<br /> Results show that flow rate and spacer configuration on the draw side infuence the flux decline due to dilution, which varied from 9% to 24% at 500mL cumulative volume. This effect was not captured by the calculation of the water flux and was attributed to changes in the mass transfer coecient on the draw side, which was used as a fitting parameter. Those changes could be caused by the used spacer type and stagnant zones between spacer laments, but more experiments are necessary to investigate this further.<br /> No flux decline due to biofouling was observed and the application of a feed spacer did not lead to significant differences. Flux decline during the baseline and biofouling without a feed spacer was 23±2% at a cumulative volume of 600mL. With a feed spacer flux decline was 26±4% during the baseline and 251% during biofouling. There was no difference between the biofilm grown in experiments with and without a feed spacer.<br /> An equation was developed for the estimation of water flux influenced by bio lm growth. It represents the biofilm analogously to the membrane support layer relying on the concept of cake-enhanced concentration polarization. The equation predicted a flux decline of 5% due to biofouling. Biofilm growth was probably reduced by high shear forces and short experiment durations and its effect on flux might have been lessened by low feed solution concentrations. The equation did not represent the biofilm or the mechanism correctly and again more experiments are necessary to nd out what caused the biofilm to be without influence on the flux and how it can be represented correctly.

Fluvial ecosystems are highly dynamic, with spatio-temporal fluctuations mainly driven by the sediment and flow regime. Over the last centuries humans have spent much effort taming and exploiting river systems for their benefit and interests. The anthropogenic exploitation, such as channelization or hydropower production, has considerably altered river ecosystems, including their sediment regime. The aim of the present study was to better understand the effects of altered sediment regimes on brown trout <em>Salmo trutta</em> and their diet. We studied two groups of alpine streams with a near-natural and a depleted sediment regime, respectively. Study reaches were sampled by quantitative electrofishing and kick-netting. Biotic variables on the population level were measured, such as trout biomass and densities, and macroinvertebrate community composition, as well as on the level of the individual fish (Fulton’s body condition factor, stomach contents, food electivity indices). To further assess the impact of sediment alteration selected abiotic variables were measured (Pfankuch stability index, d90 of sediment, CPOM, FPOM, degree on inner clogging). The relationship between abiotic and biotic variables was analysed through stepwise linear regression (linear models and linear mixed models).<br /> We hypothesized that (i) particulate organic matter content in the sediment is generally higher in sediment-depleted streams as compared to streams with a near natural sediment regime, and (ii) trout in streams with a near-natural sediment regime show higher proportions of terrestrial invertebrates in their diet than trout in sediment-depleted streams.<br /> Our categorical variable (near-natural vs. depleted) proved to be an unsuitable descriptor for the pronounced variability observed in the study reaches, both for the biotic and the abiotic variables and on the two hierarchical levels. However, hydromorphological characteristics such as the physical stability of a reach or the particulate organic matter content in the sediment showed complex, but significant influence on brown trout and their diet, also through linkage of different trophic levels.<br /> This study described the relationships between selected abiotic variables that are influenced by sediment alterations and the structure and function of aquatic communities. The results contribute to a better understanding of the high complexity in dynamic fluvial systems and hence to the protection and restoration of these valuable ecosystems and the services they provide.

Environmental stress is a fundamental force influencing species distributions and abundances in many habitats globally. The role of environmental stress may be increasing in a wide range of locations due to anthropogenic factors including chemical pollution, habitat degradation, and climate change. These abiotic stressors often combine to cause complex effects and challenge researchers to accurately assess and predict impacts at different levels of biological organisation. Thus, understanding how multiple stressors damage ecological systems is an important research goal for ecotoxicologists and ecologists.<br /> Over recent decades, concern has mounted regarding the threat posed by chemicals discharged to waterways from municipal wastewater, as opposed to industry or agriculture, on aquatic ecosystems. Municipal wastewater treatment plants (WWTPs) are designed to remove contaminants prior to discharge, but total elimination using traditional technologies is often impossible. This means treated wastewater effluent often contributes a wide range of contaminants to the environment, including both micropollutants (e.g., low concentrations of pharmaceuticals and pesticides in mixtures) and nutrients. However, it is poorly understood how the effect of these compounds act together on the receiving ecosystems. My thesis is part of a mesocosm experiment at Eawag to investigate how nutrients modify the toxic effects of micropollutants, and focuses on the responses of the freshwater amphipod Gammarus fossarum as a model study organism to these abiotic stressors.<br /> A recent meta-analysis of multiple stressor effects suggests the most common interaction is antagonistic (i.e., one stressor cancels the other one out), and previous work has shown that nutrients can dampen the effects of pesticides on freshwater invertebrates. Thus, the main hypothesis I tested was that there is an interaction of effects of nutrients and toxicants and that nutrients reduce (‘mask’) the negative effects of micropollutants found in wastewater. Here I assumed that nutrients improve food resources for amphipods (for example, promoting the microbial conditioning of leaf discs). As a result, amphipods might be better able to cope with the stress caused by micropollutants, which should increase metabolic activity and thus represent an energy demand. Therefore, we predicted that a micropollutant treatment would have strong negative effects on gammarids, while the combined presence of nutrients and micropollutants would show effects more similar to the controls, which would constitute the best conditions.<br /> The experiment was conducted using the Maiandros experimental flumes system at ARA Bachwis in Fällanden. The design involved four water quality treatments that were each replicated in four channels (16 channels in total). Each channel contained 14 amphipods in individual cages and four control cages (amphipods absent). River water only from the Glatt was used as the control treatment, and river water dosed with a solvent (methanol) was used as technical control. The third treatment consisted of a mixture of micropollutants representative for wastewater in Switzerland in composition and concentration. For the last treatment, nutrients (nitrogen and phosphorus) were added to this mixture. These two mixtures were dosed to Glatt river water with the methanol solvent. The influence of nutrients on the effects of the micropollutants treatment is therefore the main research interest of this thesis.<br /> In my thesis, I tested the hypothesis that nutrients mask the effects of micropollutants using three <em>Gammarus fossarum endpoints</em> (survival, growth, and consumption) during a five-week experiment.<br /> The results were equivocal and there was large variation observed in the treatments. Survival was reduced in the nutrient treatments compared to micropollutants, while no significant effects of treatments were found for growth and consumption. The initial size of gammarids was evenly distributed over treatments and significantly explained growth but not survival at the end of the experiment.<br /> My results do not strongly support the hypothesis tested that nutrients reduce a negative effect of micropollutants, although they do not necessarily reject it. This shows the complexity of the topic investigated and points to the need for further research regarding the ecosystem effects of multiple stressors in wastewater.

Just about 150 years ago, the three-spined stickleback, Gasterosteus aculeatus, was introduced to Switzerland. Since then, the populations have expanded and colonize today lake as well as stream habitats. In this study I investigated if sticklebacks already underwent adaptive radiation into a benthic (stream) and a limnetic (lake) ecotype. The goal was to know if feeding efficiency on a benthic prey item differs between fish type and habitat complexity. The other aim of this study was to learn more about how habitat complexity influences feeding efficiency.<br /> To investigate these questions, I conducted a behavioural experiment where I compared different factors of feeding efficiency between fish type as well as habitat complexity. I could show that high habitat complexity strongly influences feeding efficiency in a benthic diet, possibly because of higher difficulty to detect prey without sight.<br /> Additionally my results suggest that there is type-specific variation in prey detection as well as overall feeding efficiency.

In a small pond near Bern, Switzerland, two male types of threespined sticklebacks (<em>Gasterosteus aculeatus</em>) exist in sympatry, reminiscent in some traits of well-known sympatric stickleback species pairs from British Columbia. The focus of this study was to investigate two aspects of behaviour relevant to reproductive isolation. In one part, habitat choice of the males was explored. Males that had been caught in the pond at their respective breeding sites (offshore and nearshore) were individually placed in tanks where two features of both habitats, substrate and slope, had been modelled and we asked if they choose their site for nest building as expected from observations in the pond, in the absence of competition. In another part, females were tested for mate preference. In a simultaneous two-stimulus design, they were given the choice between one typical male of each ecotype and we asked if there is a bias in preference and if different preferences could be explained by the females’ morphology. Contrary to our expectations, neither did the males show a preference for the habitat they had been caught in, nor was the shore the preferred habitat as we had hypothesized. Male nesting habitat choice may depend on more factors than the ones tested. We found no evidence for size-assortative mate preference, but female eye size and head length were associated with a female’s mate preference. In conclusion, female mate preferences might be too broad to cause reproductive isolation in association with the two male ecotypes. However, potential assortment may also be underestimated in this experimental setup, as habitat choice of the males might also be important for female preference, but was not tested for here.

Adaptive radiation is an important evolutionary process to shape biological diversity. To understand the initial stages and early adaption processes is a major problem in evolutionary biology. The Greenland freshwater drainage systems are very young and the structure of the ecosystems is relatively simple. Due to that the Greenland study system can be regarded as a great opportunity to address questions of evolutionary biology. Threespine stickleback <em>Gasterosteus aculeatus</em> is a proven study organism to investigate these processes. Using existing knowledge of stickleback ecology and evolutionary history investigated in different regions, freshwater stickleback populations in southwest Greenland have been investigated for the first time. Body shape analysis of eighteen populations was conducted to investigate patterns of local adaption. It was found that stickleback populations in adjacent lake and streams were differed in two out of four cases. It was also found that present phenotypes where different between many lakes. In addition to that, morphology of the very diverse water bodies has also been assessed. Properties of the water bodies have proved to explain phenotypic variation among stickleback populations. Using relatively simple methods, this work gives an impression of the phenotypic diversity of Greenland stickleback populations and can be seen as a signpost for further research projects in this area.

Swiss rivers have a large potential for energy production from hydropower and there is currently a push towards to construction of small hydropower plants (SHPs, &lt;10 MW). Since the early 20s there were about 7000 SHPs running and the potential of further SHPs expansion is estimated in an annual increase of about 2,200GWh which is interesting for the planning of the “Energiestrategie 2050” to cover the loss of energy production from opting out of the nuclear energy program. However, the impact of SHPs on biodiversity and the provisioning of ecosystem services is not well known. In this study I sought to investigate whether SHPs have an impact on Swiss alpine river ecosystems, with special focus on the macroinvertebrate community and brown trout (Salmo trutta) foraging ecology, by studying near-natural and impacted stream reaches of five SHPs in Graubünden (Switzerland). I analyzed environmental data, benthic macroinvertebrate community composition and brown trout somatic condition and stomach contents. I found no significant differences but trends for benthic macroinvertebrate communities in residual reaches which might reflect a negative influence of SHPs and could be explained by environmental variables. Residual flow reaches had a more stable river channels, lower current velocities, significantly lower discharges and lower organic matter concentrations. Trout had a significantly lower somatic conditions in residual reaches compared to downstream reaches and it also tended to be lower than in upstream regions. Trout from residual reaches fed disproportionally more on EPT taxa than there were available in the benthic invertebrate community. This feeding pattern might have come at the cost of a higher energy expenditure and therefore led to reduced body condition. My study shows that SHPs had substantial impacts on stream habitat and ecosystem processes. Further, I could show that the reduced trout somatic condition in residual flow reaches may be a result of shifts in invertebrate prey availability.

A variety of organic micropollutants (MPs) enter wastewater treatment plants (WWTPs). Conventional activated sludge (CAS) treatment is one of the most important treatment steps to reduce the MP load to receiving water bodies. However, the removal of MPs during wastewater treatment is often not complete, and can lead to the formation of stable transformation products (TPs). Evidence is increasing that the receiving aquatic ecosystems are negatively affected by anthropogenic chemicals. To reduce the risk originating from the mixture of countless MPs and their TPs which are discharged from WWTPs, wastewater treatment can either be adjusted to yield a better removal of MPs, or prevalent MPs that have a high risk potential (either themselves or through TPs) can be restricted or banned by authorities. Both approaches rely on a better understanding of what influences the removal of MPs and which TPs are formed during activated sludge treatment. Several studies that tried to investigate these processes for a limited set of structurally diverse MPs have shown that studying MPs with a confined set of structural features is a necessary complement to obtain a more fundamental understanding and, hence, more predictive power. The amine functional group is highly abundant in wastewater-relevant MPs and most of the amine-containing MPs are polar organical compounds. The pH-dependent speciation of these compounds is an important aspect also relevant for many other functional groups in polar organic MPs. For these compounds, the most relevant removal process during CAS treatment is biotransformation, whereas sorption is known to be of minor importance. [...]<br /><br />Zahlreiche organische Mikroschadstoffe (Micropollutants, MPs) von verschiedenster Art und Herkunft gelangen in Kläranlagen. Dort ist das konventionelle Belebtschlammverfahren eine der wichtigsten Behandlungsstufen, um die Belastung des aufnehmenden Gewässers mit MPs zu verringern. Die Abwasserreinigung kann jedoch oft keine komplette Entfernung von MPs bewirken und sogar zur Bildung von stabilen Transformationsprodukten (TPs) führen. Immer mehr Anzeichen deuten darauf hin, dass die aufnehmenden Gewässer durch diese anthropogenen Chemikalien negativ beeinflusst werden. Um das von der Mischung aus unzähligen MPs und TPs ausgehende Risiko zu verringern, können entweder die Verfahren der Abwasserreinigung erweitert werden, um damit die Entfernung der MPs zu verbessern, oder MPs, die selbst oder durch ihre TPs ein hohes Potential haben aquatischen Ökosystemen zu schaden, können von Behörden eingeschränkt oder verboten werden. Für beide Herangehensweisen ist ein besseres Verständnis dessen nötig, was die Entfernung von MPs beeinflusst und welche TPs bei der Abwasserreinigung entstehen. Die Ergebnisse mehrerer Studien, die versucht haben diese Prozesse für strukturell vielfältige MPs zu untersuchen, zeigen, dass es vorteilhaft sein könnte, MPs mit einer eingeschränkten Menge an strukturellen Merkmalen zu untersuchen, um die Vorgänge grundlegend zu verstehen und somit Vorhersagen zu ermöglichen. Die funktionelle Gruppe der Amine ist in abwasserrelevanten MPs sehr oft zu finden. Ihre pH-abhängige Speziierung ist ein wichtiges Merkmal, das auch für viele andere funktionelle Gruppen in polaren organischen MPs relevant ist. Die meisten aminhaltigen MPs sind polare organische Chemikalien. Für diese ist Biotransformation der wichtigste zur Entfernung führende Prozess während des Belebtschlammverfahrens. Sorption hingegen ist für polare Substanzen von geringer Bedeutung. [...]

The Dagstuhl Seminar 15492 on Computational Metabolomics brought together leading experimental (analytical chemistry and biology) and computational (computer science and bioinformatics) experts with the aim to foster the exchange of expertise needed to advance computational metabolomics. The focus was on a dynamic schedule with overview talks followed by breakout sessions, selected by the participants, covering the whole experimental-computational continuum in mass spectrometry, as well as the use of metabolomics data in applications. A general observation was that metabolomics is in the state that genomics was 20 years ago and that while the availability of data is holding back progress, several good initiatives are present. The importance of small molecules to life should be communicated properly to assist initiating a global metabolomics initiative, such as the Human Genome project. Several follow-ups were discussed, including workshops, hackathons, joint paper(s) and a new Dagstuhl Seminar in two years to follow up on this one.

Darkfield and confocal laser scanning microscopy both allow for a simultaneous observation of live cells and single nanoparticles. Accordingly, a characterization of nanoparticle uptake and intracellular mobility appears possible within living cells. Single particle tracking makes it possible to characterize the particle and the surrounding cell. In case of free diffusion, the mean squared displacement for each trajectory of a nanoparticle can be measured which allows computing the corresponding diffusion coefficient and, if desired, converting it into the hydrodynamic diameter using the Stokes-Einstein equation and the viscosity of the fluid. However, within the more complex system of a cell's cytoplasm unrestrained diffusion is scarce and several other types of movements may occur. Thus, confined or anomalous diffusion (e.g. diffusion in porous media), active transport, and combinations thereof were described by several authors. To distinguish between these types of particle movement we developed an appropriate classification method, and simulated three types of particle motion in a 2D plane using a Monte Carlo approach: (1) normal diffusion, using random direction and step-length, (2) subdiffusion, using confinements like a reflective boundary with defined radius or reflective objects in the closer vicinity, and (3) superdiffusion, using a directed flow added to the normal diffusion. To simulate subdiffusion we devised a new method based on tracks of different length combined with equally probable obstacle interaction. Next we estimated the fractal dimension, elongation and the ratio of long-time / short-time diffusion coefficients. These features were used to train a random forests classification algorithm. The accuracy for simulated trajectories with 180 steps was 97% (95%-CI: 0.9481-0.9884). The balanced accuracy was 94%, 99% and 98% for normal-, sub- and superdiffusion, respectively. Nanoparticle tracking analysis was used with 100 nm polystyrene particles to get trajectories for normal diffusion. As a next step we identified diffusion types of nanoparticles in vital cells and incubated V79 fibroblasts with 50 nm gold nanoparticles, which appeared as intensely bright objects due to their surface plasmon resonance. The movement of particles in both the extracellular and intracellular space was observed by dark field and confocal laser scanning microscopy. After reducing background noise from the video it became possible to identify individual particle spots by a maximum detection algorithm and trace them using the robust single-particle tracking algorithm proposed by Jaqaman, which is able to handle motion heterogeneity and particle disappearance. The particle trajectories inside cells indicated active transport (superdiffusion) as well as subdiffusion. Eventually, the random forest classification algorithm, after being trained by the above simulations, successfully classified the trajectories observed in live cells.

The use of the black solider fly, Hermetia illucens, for conversion of organic waste streams into valuable animal protein has become a hot topic in the past decade. Large-scale protein production facilities treating up to 200 tonnes of waste per day are already in operation, with focus on protein production. On the other end of the spectrum are decentralised small-scale household composting systems focusing on waste treatment, motivated by the thought of self-sufficiency. In the middle of the scale – waste management systems treating up to 10 tonnes per day – there is of yet no alternative. There are benefits and constrains, with both large- and small-scale BSF treatment. However, by combining the advantages of the centralised large-scale protein production systems with the benefits of decentralised waste management strategies, many of the constraints can be overcome. In this paper is suggested a semi-centralised BSF-treatment approach that could bridge the lack of waste management in places current management strategies have failed. The absence of adequate organic waste management has dire health implications in low and middle-income countries and serious negative impacts on the environment all around the world. In semi-centralised BSF treatment, a centralised facility is used for fly rearing – for the production of small larvae required for the treatment – and for the refinery of the products generated from the treatment (grown larvae and residue). From the centralised BSF Rearing and Refinery (BSF R2) facility, small larvae are sent to decentralised waste treatment units located at the place of waste production. The great volume reduction occurring in the treatment (80-85% on a wet weight basis) greatly reduce the need for transportation, while the valuable products generated from the treatment (animal protein and organic fertiliser) renders the treatment an economically viable option for the clients using the treatment units, while also allowing for business opportunities for waste management entrepreneurs operating a BSF R2 facility. The flexibility in waste source and amounts possible to treat with BSF-technology, along with the refining of high-value products and the reduced need for transportation, can make the semi-centralised BSF-treatment approach a key player in providing organic waste treatment in areas that today are either completely lacking any service or that are not adequately treating the organic fraction. This would substantially improve the health of millions and considerably reduce the negative environmental impacts associated with poor organic waste management.

Behavior that has changed following promotion campaigns is usually not maintained at its initial level. Psychosocial factors for initiating behavior are often not the same as for the continuation of health behaviors such as water treatment and are much less understood. Better knowledge of factors for behavioral continuation would help to improve programs, both in the design of strategies for sustainable behavior change and by defining stronger criteria for the evaluation of sustainability. This study compared the mindsets of caregivers who continuously performed household drinking water treatment over time with individuals that stopped doing so in a population sample from Chad. Several factors from health psychology based on the Risks, Attitudes, Norms, Abilities, and Self-Regulation (RANAS) model were used to compare the two groups and examine their differing development. Normative factors such as others’ behavior, personal obligation, social support and discourse, perceived self-efficacy convictions, action control, and intention best discriminated between the two groups and developed significantly more positively over time for continuers of water treatment. These factors should be considered when designing future interventions intended to lead to sustainable behavior change.

In the modular experimental building known as NEST, Eawag and Empa – together with industrial and scientific partners – are investigating new forms of living and working, innovative construction methods and energy-efficient technologies. In the Water Hub project, researchers are studying, for example, how urine-separating toilets can be used to save water and recover valuable nutrients.

A lake’s sediments are a window onto the past – the various layers deposited over time can provide valuable information on changes in local environmental conditions. Eawag researchers have studied how the settlement and economic development of the Joux Valley in Canton Vaud is reflected in the sediments of Lake Joux.

What is required to facilitate the adoption of new technologies such as potable water reuse? According to a study carried out by environmental social scientists in California, users need to see not only how an innovation benefits them personally, but also that it is compatible the community’s values and can become a routine part of daily life.

In order to protect aquatic ecosystems from the adverse effects of chemical pollutants it is important to understand the factors that can influence their impact on organisms in the environment. Aquatic organisms, such as microalgae, are not only exposed to chemical pollutants, but also to additional environmental stressors, such as ultraviolet radiation (UVR). In combination, chemical and environmental stressors cause so-called multiple stressor effects. Effects resulting from combined exposure to multiple stressors might be predicted from the known effects of each individual stressor. However, multiple stressor effects might also be higher (synergism) or lower (antagonism) than expected, depending on the stressor combination. Stressor effect interactions are believed to be one reason for the limited predictability of multiple stressor effects. Moreover, organisms can acclimate to stressful environmental conditions which may increase or decrease (cotolerance) their sensitivity toward chemical pollutants and thus change multiple stressor effects. [...]<br /><br />Um die aquatische Umwelt vor den negativen Effekten von Schadstoffen schützen zu können, muss man diejenigen Faktoren verstehen, die deren schädlichen Auswirkungen auf die Umwelt beeinflussen. Wasserlebewesen, wie z.B. Mikroalgen, sind nicht nur chemischen Schadstoffen allein ausgesetzt, sondern zusätzlich auch weiteren Umweltstressoren, wie Ultraviolettstrahlung (UVR). In Kombination können chemische Stressoren und Umweltstressoren sogenannte Multiple-Stressor-Effekte verursachen. Die Effekte die aus einer kombinierten Exposition gegenüber mehreren Stressoren resultieren, können gegebenenfalls anhand der Effekte der einzelnen Stressoren erklärt werden, können aber je nach Stressor auch höher (synergistisch) oder niedriger (antagonistisch) sein. Interaktionen von Stressor-Effekten werden als ein Grund für die begrenzte Vorhersagbarkeit von Multiple-Stressor-Effekten angesehen. Darüber hinaus können sich Organismen auch an widrige Umweltbedingungen akklimatisieren was unter Umständen ihre Sensitivität gegenüber chemischen Schadstoffen erhöhen oder vermindern (Ko-Toleranz) kann. [...]

The main advantage of membrane filtration processes is efficiency of separation, which allows to reach very high quality treated water. However, main disadvantages are cost of the treatment (electricity, chemicals) and membrane fouling, which can severely reduce the efficiency of the filtration process. Biofouling and biofilm formation is a major type of fouling due to biological deposition and activity on any membrane type surface. Biofilms on membranes significantly reduce permeation rates, and as such are removed and controlled by using chemical treatments (Flemming 2002). [...]<br /><br />Die Membranfiltration ist attraktiv für die Trinkwasseraufbereitung, da sie Partikel sicher zurückhalten kann. Nachteile der Membranfiltration sind die hohen Kosten, verursacht durch den Energie‐ und Chemikalienverbrauch, sowie das sogenannte Fouling, welches die Effizienz der Filtration stark beeinträchtigen kann. Eine wichtige Form des Foulings ist das Biofouling bzw. Biofilmwachstum. Biofilme können die Permeabilität der Membran stark beeinträchtigen und werden in der Regel durch regelmässige, chemische Reinigung entfernt (Flemming 2002). [...]

With the global nanotechnology market growing rapidly, nanomaterials are being increasingly released into aquatic environments, where they can undergo modifications and sedimentation, which will put benthic organisms at risk. Of particular interest is the study of nanomaterial effects on periphyton, a community of auto- and heterotrophic microorganisms embedded in an extracellular polymer matrix that covers submerged surfaces in aquatic ecosystems. Although periphyton assumes important functions in ecosystems, like primary production, little information is available on its sensitivity to nanomaterials and how these might be transferred to higher trophic levels in food webs. [...]<br /><br />Avec le développement des nanotechnologies, le risque de contamination des milieux aquatiques par les nanoparticules est de plus en plus important, perturbant ainsi les communautés benthiques dans ces écosystèmes. Parmi ces communautés, le périphyton est un ensemble de microorganismes auto- et hétérotrophes, inclus dans une matrice d’exopolymères et fixés sur un support solide immergés dans l’eau. En dépit du fait que le périphyton joue un rôle essentiel dans les cours d’eau, peu d’informations sont disponibles sur sa sensibilité aux nanoparticules ainsi que sur les effets sur la chaine trophique. [...]

The stone crayfish <em>Austropotamobius torrentium</em> is an endangered species native to the northeastern parts of Switzerland. Since the 19th century its populations have been declining due to habitat deterioration, fragmentation and the devastating crayfish plague that has been introduced by invasive crayfish species. The goal of this study was to analyze the genetic diversity and structure of the remaining stone crayfish populations in the Canton of Thurgau and gain information about conservation measures needed to ensure the long term survival of these populations. For this purpose microsatellite data of twelve stone crayfish populations were analyzed and genetic diversity, effective population size and differentiation among the populations were estimated. Overall low genetic diversity and effective population sizes were observed in most populations whereas differentiation was strong between all population pairs. The genetic structure of the populations was virtually unrelated to drainage structure and I did not observe signficant isolation-by-distance despite the strong overall genetic differentiation. This is characteristic of small and isolated populations in which genetic drift is much more important than gene flow. Even though effective population sizes could only be estimated with high uncertainty, the generally low values suggest rather small effective population sizes for most of the populations. Some estimates are so low that it has to be feared that evolutionary potential has already been lost to a certain amount. Many populations may be too small to even ensure short term survival over five generations. This result is alarming and it is important that conservation measures are initiated as soon as possible. Applicable conservation measures for crafish populations are described in detail in the Swiss Action Plan for crafish. This plan includes proposed genepool sites for translocations and reintroductions. However, my results suggest that these populations (Ruti, Zezikon, Baltschhuuse) are not necessarily better suited than other populations in canton Thurgau, because some showed either low genetic diversity or population density. To increase population size as well as genetic diversity of the populations I recommend to improve the habitat quality by habitat restoration and to reintroduce animals from breeding programs.

Many micropollutant transformation products (TPs) can be formed out of their respective parent compounds during biological wastewater treatment. However, as the identities of many<br /> TPs are not known, assessing the risk to downstream aquatic communities is not feasible. The objective of this thesis was to identify unknown TPs caused by biological wastewater treatment. Prior to the work described in this thesis, samples from the in infuent and effluent of a wastewater treatment plant in Dubendorf, Switzerland were collected and measured using liquid chromatography coupled to high-resolution mass spectrometry (LC-ESI-HR-MS). The resulting data was processed using a nontarget screening approach that included principal component analysis (PCA) to identify peaks characteristic of pre- and post-treatment samples. Subsequent linkage analysis set up possible pairs of parent compound and corresponding TP. Within the scope of this thesis, a method was developed to obtain a suitable selection of those postulated linkages for targeted tandem mass spectral (MS/MS) measurements. This method was based on visual inspection and assessment of the extracted ion chromatograms (EICs) of the linkages. The obtained MS/MS data was prioritized for evaluation in two di erent ways. In one approach, linkages involving simple structural transformation reactions were selected for structure elucidation based on spectral similarity between parent compound and corresponding TP. In one example this led, together with openly accessible structure identi cation tools and databases, to the tentative suggestion of alcohol ethoxylates as potential precursors for the formation of unknown micropollutant TPs. In the second approach, spectra of linkages associated with (de)conjugation reactions were directly matched to the library entries of the mass spectral database MassBank. In one case, a conjugate of the cough suppressant Dextromethorphan was tentatively identified to get deconjugated during wastewater treatment.

This work focuses on Tonalide, a small fragrance molecule with an octanol-water partitioning coefficient of 5.7. Fragrances are an environmentally relevant substance class because they are produced in high amounts and strongly utilized for a multitude of products. The input into the aquatic environment is significant due to continuous use and low removal rates in waste water treatment plants. Their partly high hydrophobicity makes dietary uptake and bioaccumulation very likely. In this work, a cell line-based model for the intestinal barrier in fish and its application for compound permeability testing is presented and tested with Tonalide in a recently developed setup.<br /> The model is based on intestinal epithelial cells from rainbow trout that were seeded into permeable supports. This creates a separation into an apical, representing the luminal side, and a basolateral, representing the blood-facing side, compartment, which generates a system in which permeation can be precisely studied. Complementary, an airtight stainless steel chamber was used for the compound exposure to reduce loss through evaporation and material binding. Furthermore, the system allowed the use of a passive dosing system for the exposure of hydrophobic substances as well as apical and basolateral stirring. For the basolateral compartment two setups were used: Medium without sink which leads to compound concentration gradient decrease over time and medium with sink used to maintain the concentration gradient. This setup is well suited for the assessment of fragrance permeation because it reduces compound loss, a common problem caused by their relative hydrophobicity and volatility.<br /> It was found that experimental system and methodology are suitable to test the Tonalide permeation across the RTgut-GC cell layer. The accumulation in the cells and the permeation from the apical into the basolateral compartment was clearly detected through measurement of Tonalide mass in the different compartments. The permeation through permeable supports with and without cells was not significantly different. The same is true for the permeation with an without passive sink. The Tonalide permeability for experiments without sink is 4.95*10^-6 ± 8.3*10^-7 cm/s for cell-free and 6.595*10^-6 ± 7.2*10^-7 cm/s for cell-containing permeable supports, for experiments with sink the corresponding values are 6.667*10^-6 ± 3.3*10^-7 cm/s and 6.537*10^-6 ± 1.6*10^-6 cm/s. The accumulation in the cells increased twofold through the use of the passive sink. The measured permeation was compared to and evaluated with the help of permeabilities of other compounds. This revealed a dependency of substance lipophilicity and permeability across cell layers in permeable supports.

Removal of bacteria and reduction of the assimilable organic carbon (AOC) are two of the main goals in drinking water treatment. In a gravity‐driven membrane (GDM) system the bacteria are retained by an ultrafiltration membrane while the biofilm on top of the membrane reduces the AOC concentration. But with the ageing of the biofilm, the AOC concentration in the permeate increases and the drinking water quality deteriorates (Derlon et al., 2014).<br /> In this thesis, the influence of multiple GDMs in series on the permeate quality is investigated. An experiment with five GDMs in series, fed with a 5 mg C L^‐1 acetate feed, is conducted. The permeate after each GDM was analyzed for its acetate concentration, total organic carbon (TOC) concentration and total cell count (TCC). The biofilm on each GDM was analyzed for its TOC, TCC and adenosine triphosphate (ATP) content as well as its biofilm resistance. The mean biofilm thickness was measured with optical coherence tomography.<br /> The results of the experiment showed a decrease of TCC in the permeate at the time of sampling, as well as after three days of incubation at 30 °C, over the number of GDMs. The TOC, TCC and ATP in the biofilm decreased over the number of GDMs. So did the biofilm resistance and the mean biofilm thickness. These results indicate a decrease of AOC over the number of GDMs.<br /> No flux stabilization over the five GDMs in series was observed. The flux varied between 3 L m^‐2 h^‐1 and 4 L m^‐2 h^‐1. This flux is higher than expected and can be explained by the low biofilm resistance of the GDM 2 to 5. Biofilm 1 displays by far the highest biofilm resistance to flux.<br /> Overall, multiple GDMs in series result in a decrease of TCC in the permeate and therefore in an increase of the permeate quality. The flux obtained was higher than expected. Hence, multiple GDMs in series should be further investigated for drinking water treatment.

Farmed and natural brown trout populations in Switzerland have suffered severe losses (60% decrease in population size) within the last 35 years. Proliferative Kidney Disease (PKD) in salmonids - in conjunction with eutrophication and human alterations to natural water flow regimes - has been identified as the main contributor of these losses. <em>Tetracapsuloides bryosalmonae</em> (<em>Tb</em>), a myxozoan parasite, is the causative agent of PKD. <em>Tb</em>’s primary and most abundant host, the bryozoan <em>Fredericella sultana</em> (<em>Fs</em>), ensures Tb transmission to salmonid fish by shedding of infectious parasitic spores. Thus, <em>Fs</em> is crucial in PKD spread and key to efforts aimed at disease containment. Bryozoans are colonial filter feeders, hence their distribution is likely to be governed by nutrient availability in a stream. Effluent from waste water treatment plants (WWTPs) is a persistent and extensive source of micropollutants (chemical and natural trace pollutants) that can have detrimental effects on freshwater inhabitants. The study at hand assessed the effect of effluent on the occurrence of <em>Fs </em>and, by extension, the possible implications of effluent on PKD spread. Growth, survival and <em>Tb</em> infections of Fs colonies were determined in artificial river systems with three concentrations of effluent (0%, 30%, and 70%). This study revealed that effluent enhances growth and survival of <em>Fs</em> while, to some extent, promoting <em>Tb</em> infections. These findings suggest that sites downstream of WWTPs might pose hotspots of <em>Fs</em> abundance. Such an increase in <em>Fs</em> biomass, and subsequently in material available for parasite exploitation, should facilitate persistence of<em> Tb</em> in a river and potentially exacerbate the decline of trout populations.

In the context of nutrient recovery research, urine is collected separately at Eawag Dübendorf (CH) and treated with biological nitrification. It is important to have an appropriate technique to measure the nitrite concentration in the reactor as nitrite, which is the intermediate product of nitrification, inhibits the process.<br /> The objective of this project is to test UV-Vis spectrophotometry for the simultaneous estimation of nitrite and nitrate in the nitrified urine. For this purpose, the influence of changing nitrite and nitrate concentrations and of the urine background composition on the absorbance spectrum and the estimation accuracy is analysed. Furthermore, the stability of the estimation performance of the linear model under changes in the urine composition is evaluated. [...]

Aquatic biodiversity in rivers and streams is threatened in many regions worldwide. As biodiversity loss has severe consequences on environmental processes it is important to understand the cause of decline and to predict the state of change of biodiversity in space and time. In this study a spatially explicit habitat distribution model for aquatic macroinvertebrates in Swiss watercourse networks was developed using the national biodiversity monitoring data (BDM). The aim was to identify the spatial environmental variable datasets available nationwide, which explain the diversity of macroinvertebrates, in order to predict and upscale their nationwide distribution.<br /> The modelling was carried out with a generalized linear model that related the richness of the Ephemeroptera, Plecoptera and Trichoptera species (EPT) and the IBCH family and higher order taxa (indice biologique global normalisé - IBGN, adapted to Swiss watercourses) to 38 environmental variables. The model parameters were then used to predict the EPT species and IBCH taxa richness at both levels to the landscape scale.<br /> The results show that land-use (forest, pasture, cultivated land and developed area) and topology (elevation and slope) variables influence the Swiss macroinvertebrate richness distribution at a landscape level. However, they do not influence all macroinvertebrate orders equally: the EPT species react more sensitively towards land-use changes than the IBCH taxa, resulting in opposing spatial predictions on richness at the landscape scale. This indicates firstly, that the diversity pattern of one macroinvertebrate group cannot be used as a proxy of another macroinvertebrate group and secondly, that a better understanding of the the relationship between environmental variables and macroinvertebrate richness is gained when the focus is placed on a few sensitive macroinvertebrate species with a clearly defined ecological niche (eg. EPT species), than when a broad mixture of macroinvertebrate taxa with varying sensitivity and less clearly defined ecological niche (eg. IBCH taxa) are considered.

Since the 16th century pressure from human use and following alterations of the river flow is increasing exponentially. With the result that 50 percent of the rivers in Switzerland below 600 m altitude are in a deficient state. Due to flood events occurring with alarming frequency, environmental awareness has risen in the last three decades, which led to a paradigm shift in hydraulic engineering. Although the number of restoration projects is increasing constantly, success evaluations are still scarce and the lack of knowledge about the impact of the applied measures is high.<br /> The goal of this master thesis was to perform an evaluation of the success of the ecological goals of the restoration project of the Wutach (CH/GER). With the emphasis on ecology, biotic and abiotic indicators described by Woolsey et al. (2005) were analyzed to evaluate the degree of achievement of the project goals. Additionally, two new indicators were assessed to quantify the success of natural reproduction of brown trout <em>Salmo trutta fario</em>. To evaluate the change caused by the restoration, two additional reaches, a natural and a channelized reach, were examined. [...]<br /><br /> Seit dem 16 Jahrhundert steigen Nutzungsdruck und Verbauung der Fliessgewässer exponentiell an. In Höhenlagen bis 600 m weisen rund 50 Prozent aller Fliessgewässer der Schweiz eine ungenügende Gewässermorphologie auf. Infolge vermehrter Hochwasserkatastrophen in den letzten Jahrzehnten etablierte sich ein gewisses Umweltbewusstsein, das zu einem Paradigmenwechsel im Wasserbau führte. Obwohl die Zahl der Revitalisierungsprojekte seither stark steigt, werden Erfolgskontrollen selten durchgeführt, und der Wissensmangel über die Auswirkungen der angewandten Massnahmen ist gross.<br /> Diese Masterarbeit ist eine Erfolgskontrolle der 2010 begonnen Revitalisierung an der Wutach (CH/D). Zur Beurteilung der Revitalisierung wurden biotische und abiotische Indikatoren gemäss Woolsey et al. (2005) untersucht und zusätzlich zwei neue Indikatoren formuliert, die den Erfolg der Naturverlaichung der Bachforelle <em>Salmo trutta fario quantifizieren</em>. Die Indikatoren beschreiben Schlüsselelemente oder -prozesse der Fliessgewässer. Um den Erfolg auf die Massnahmen der Revitalisierung zurückführen zu können, wurden zusätzlich zwei angrenzende Referenzstrecken, eine naturnahe und eine kanalisierte, untersucht. [...]

The emergence of intraspecific variation is thought to be an important first step towards specia-tion. To understand which drivers promote the emergence of initial variation would increase our knowledge of predicting the likelihood of a population to undergo ecological speciation. To assess some of the possible drivers of initial variation I studied Arctic charr (<em>Salvelinus alpinus</em>) from 16 lakes of the Vatnahverfi peninsula in southern Greenland. I assessed variation of overall body form depending on lake variables such as lake area and lake depth as well as presence or absence of sticklebacks using a geometric morphometrics approach. Further, variation in trophic levels and its correlation with lake variables was assessed using stable isotope analysis. The variation of total morphospace, estimated from convex hull areas, did not significantly increase with lake area or depth. However, a significant directional expansion of morphospace into negative PC1 values, rep-resenting slender body shape typical for planktivorous charr, was observed with both increasing lake area and depth. Variation in trophic levels, represented by the δ¹⁵N -range of a lake’s charr population, significantly increased with lake area and depth, suggesting that food chains of charr become longer and that there is increasing specialization on piscivory in larger and deeper lakes. Further, I found that variation in trophic levels within a population was not constrained by mor-phological variation. High variation in trophic levels could be observed across the entire range of morphological variation, whereas large morphological variation was always associated with large variation in trophic levels.

Persistent organic pollutants (POPs) are known to accumulate in the polar regions. As one of the priority POPs hexachlorobenzene (HCB) concentrates in Antarctic biota and biomagnifies in the foodchain. Southern hemisphere humpback whale populations accumulate large amounts of HCB in their blubber. Seasonal migration leads to an increase in concentrations and potential re-mobilization. However, to date, no studies assess the toxic effects of HCB on humpback whales. In this thesis a passive dosing setup for HCB was established, using silicone O-rings as a reservoir. Thereby losses due to sorption and evaporation are compensated for. O-rings as reservoir were loaded with HCB to establish a stable concentration in aqueous medium by equilibrium partitioning. The partitioning coefficient between loading buffer and silicone was determined as log<em>K</em>_{<em>LB:sil</em>} = -2.18. Loaded O-rings were used to dose cell culture medium with and without FBS. The resulting partitioning coefficients between silicone and medium were log<em>K_sil:medium</em> = 4.96, and log<em>K_{sil:medium;1%FBS}</em> = 3.66. It was assessed that 95% of HCB bound to serum constituents in medium with 1% FBS. The passive dosing setup was applied for HCB toxicity tesing using humpback whale fibroblast cell lines. No effect on cell viability was detected by conventional passive dosing of HCB. However, cells exposed immediately to HCB during seeding followed by passive dosing of 3h showed a significant reduction in metabolic activity of 14% compared to control. Afterwards subsequent recovery was observed within 24 hours. This effect was less distinctive in primary subcultured HuWa1 cells. Effect of HCB on membrane integrity and cellular resistance (measured by impedance spectroscopy) showed a trend to increase rigidity and resistance respectively, but no significant effect was found. Similarly, no final conclusion was drawn whether HCB causes significant DNA damage (measured by alkaline comet assay) or not. This study shows that passive dosing is a suitable setup for <em>in vitro</em> toxicity testing of HCB, and it presents the first results on toxicity of HCB to humpback whale cells.

Aerobic granular sludge (AGS) is a new technology for biological treatment of wastewater. Simultaneous removal of organic matter, nitrogen and phosphorus is possible in an AGS reactor due to the large physical size of granules and their heterogeneous structure. While sufficient removal efficiencies of C and P have been achieved, N removal from municipal wastewaters using AGS still remains a challenge.<br /> To address this knowledge gap, a model was developed in SUMO software to assess the mechanisms driving simultaneous nitrification and denitrification (SND) in a granular sludge reactor. Nitrification and denitrification can be accomplished in a single reactor due to coexistence of aerobic and anoxic zone in granules. Therefore, the objective of this master’s thesis is to evaluate the influence of oxygen concentration and anoxic volume in the granules on SND performance. Another objective is to evaluate the contribution of phosphorous accumulating organisms (PAO) on SND as PAOs are mainly responsible for the denitrification in AGS.<br /> The granular sequenced batch reactor (SBR) module in SUMO was used to simulate mass transport and conversion processes occurring in the reactor. A low-strength influent with particulate organic carbon, which is typical for the municipal wastewater, was used in the study. A total COD concentration was 420 g_COD.m^-3. The model included growth and decay of nitrifiers, ordinary heterotrophs and PAO. Three case studies were analyzed with low, intermediate and high granulation. The simulations were performed under different airflow resulting in different dissolved oxygen concentration in the bulk.<br /> The highest SND of 96% was achieved for the simulation with intermediate granulation and oxygen concentration in the bulk reaching 1.2 g_O2.m^-3. Complete nitrification occurred in this simulation. The fraction of anoxic volume in the granule reached 100% and remained high during most of the aerobic period, which is significantly higher than the anoxic volume in cases with low or high granulation. In case with intermediate granulation, high PHA concentrations are found in anoxic layers of the granule. Therefore, there is a sufficient amount of organic carbon for denitrification by PAOs. In cases with low and high granulation, most of the PHA was concentrated in the aerobic layers and was not available for denitrification by PAOs.<br /> To conclude, this study shows that aerobic granular sludge can be an effective technology for treatment of municipal wastewater, achieving high nitrification and SND efficiencies. However, special consideration shall be paid to oxygen concentration, anoxic volume in the granule and organic carbon availability in the anoxic zone.

Die Bevölkerung wird via Medien regelmässig über verkeimte Wasserinstallationen und deren Gefahren informiert. Dies führt dazu, dass Planer ind Installateure vermehrt über mögliche hygienische Präventivmassnamen Auskunft geben müssen. Weiter werden Planer durch neu definierte Grenzwerte in Normen und Labels zu neuen Konzepten gezwungen. Es gilt, ernauerbare Energien oder Abwärme aus thermischen Prozessen zu nutzen. Dabei kommt es oft zum Widerspruch zwischen energetisch optimaler und hygienisch einwandfreier Warmwasserversorgung.