Master Thesis Possible Topics in Urban Water Management · Master Thesis Possible Topics in Urban...

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Chairs of Urban Water Management

Master Thesis Possible Topics in Urban Water Management

Updated: 20.04.2017 You find the responsible contact in the contact information at the end of each topic description. If you are looking for a topic related to a given topic, you may also contact the responsible person. Irrespective of the topic, you can also contact the assistants of the Chairs of Urban Water Management for general advice: Maike Gaertner, Rachel Barrett, Martin Vogt Office: HIL G 31.2 Email: [email protected], [email protected], [email protected], Tel.: +41 44 633 30 863 If none of the listed topics fits you, you are encouraged to inform yourself about the different research fields at Eawag. If you are interested in a Master thesis in one of the groups, please contact the responsible researcher directly. In any case, make sure that a clear formulation of your tasks is done and arranged with the responsible professor (Prof. Maurer or Prof. Morgenroth) before you start with your thesis! You can find the different research groups under the following links: http://www.eawag.ch/forschung/eng/schwerpunkte/index_EN http://www.eawag.ch/forschung/sww/schwerpunkte/index_EN

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Table of Contents Monitoring pharmaceuticals and pesticides in combined sewer overflows ......... 3

Sanitation systems in the context of urban India: comparison of scales and levels of centralisation ........................................................................................ 5

Evaluating the mechanisms and performances of aerobic granular sludge for the treatment of municipal wastewater ............................................................... 8

Soft-sensing of a urine nitrification reactor for nutrient recovery ....................... 11

Monitoring wear-and-tear in pH sensors .......................................................... 13

Emissionsorientierte Erfolgskontrolle für besseren Gewässerschutz bei Regenwetter ..................................................................................................... 15

Evaluation of Membrane Integrity for Potable Water and Grey Water treatment ......................................................................................................................... 18

Low-pressure Membranes (GDM) as a Pretreatment of Reverse Osmosis for the Desalination of Seawater in Singapore ...................................................... 20

Laboratory investigation of physical disintegration of gross solids in the sewer 22

Stabilizing urine nitrification as a pretreatment for fertilizer production: development, test and evaluation of novel control concept .............................. 24

What is the impact of heavy rainfalls on a potential river contamination by engineered nanomaterials? .............................................................................. 26

Obtaining Sludge Settling Properties via Image Analysis ................................. 28

Growth of microorganisms in treated grey water as part of Blue Diversion AUTARKY project ............................................................................................. 30

How does urbanization influence groundwater recharge of alluvial aquifers? .. 32

Overland Flow Network delineation allowing for flow divergence ..................... 34

Dynamic Control and Monitoring of the Waste Water Treatment Process ....... 36

Amine-containing micropollutants – Modeling their pH-dependent uptake and biotransformation in sludge bacteria ................................................................. 38

Automatic correction of systematic errors of rainfall-runoff models .................. 40

Calibrating urban inundation models using novel information from social media ......................................................................................................................... 42

Evaluating the influence of hydrolysis on the quality of drinking water produced during Gravity-Driven Membrane filtration ........................................................ 44

Ambient water quality assessment of micropollutants in Switzerland ............... 46

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Monitoring pharmaceuticals and pesticides in combined sewer overflows

Background and project description Many wastewater treatment plants in Switzerland are being upgraded to enhance removal of micropollutants (e.g. pharmaceuticals, personal care products, pesticides). However, it is important to realise that up to half of the overall rain-driven micropollutant load can be discharged via combined sewer overflows without treatment (Fig 1).

Fig. 1. Active combined sewer overflow during rain event in spring 2016.

Monitoring micropollutants in sewer overflows is challenging due to the high temporal and spatial variabilities of load and concentrations during discharge events. Passive sampling might be a simple and promising solution to this challenge. Monitoring micropollutants via passive sampling in sewer overflows needs validation and therefore a comparison to active water sampling is needed (Fig. 2).

Fig. 2. Passive sampling disks (4 pieces) in the sewer system. In addition, the tube to

take active water samples via automated sampler is shown.

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We currently monitor sewer overflows in 19 catchments with different land uses with the aim to identify locations with potentially critical concentrations of micropollutants.

Objective The objective of this project is to evaluate the performance of passive sampler to monitor micropollutants in combined sewer overflows.

Tasks Depending on the start of the master thesis the main focus will be:

1. Comparison of passive sampling with active water sampling in a pilot scale flow channel. Experiments will be conducted during rain events. Additionally, a previously observed high initial uptake rate of the passive sampler disks should be investigated with batch experiments in the laboratory.

2. Testing our hypothesis that levels of specific micropollutants are related to urban land use. E.g. a high fraction of garden areas leads to critical pesticide concentrations in sewer overflows. The tasks are based on the samples of the field monitoring campaign and consist of sample preparation in the laboratory for analysis and evaluation of the obtained monitoring results with respect to correlations with land use (programming environment R, GIS based).

Specific information This project will be performed in the department of Urban Water Management at Eawag. Office space with computer and experimental facilities will be provided. Advisors and supervisors Prof. Dr. Max Maurer Dr. Christoph Ort (Eawag) Lena Mutzner (Eawag) Contact information Name: Lena Mutzner Email: [email protected] Phone: +41 (0)58 765 5929

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Sanitation systems in the context of urban India: comparison of scales and levels of centralisation

Research question What level of centralisation of sanitation systems is most appropriate for different contexts of urban India?

Background and project description The historic approach to urban sanitation in Europe is wastewater treatment in centralised plants. This approach has often been translated to other contexts, where it has failed regularly. Furthermore it requires a certain population density in order to be cost effective. Therefore smaller scale and often decentralised sanitation solutions gained the interest of the expert community in the last couple of years. In urban India, thousands of small-scale wastewater treatment systems have been implemented over the last decade, as part of a requirement for construction projects, allowing for the reuse of treated wastewater. However, it is known that these small-scale sanitation systems are often not working properly, and only 50-75% of the water can be reused at the building level. Life-cycle costs are commonly not considered in decision-making during the planning and design phase. New apartment buildings are typically not fully occupied from the beginning, leading to idle capacity and underperforming treatment plants during the first years of operation. Despite these challenges, the Government of the state of Karnataka has recently made it a requirement for all residential buildings with more than 20 apartments to build a wastewater treatment unit. However, in view of the difficulties involved in its implementation, this policy is being questioned by many stakeholders, requiring the government to reassess its suitability. Eawag/Sandec is partnering with the Indian Institute of Technology (IIT) Madras and BORDA, Germany to carry out the 4S project (Small-Scale Sanitation Scaling-Up), the first systematic assessment of small-scale sanitation systems in South Asia. 4S is funded by the Bill & Melinda Gates Foundation and its main goal is to develop evidence-based policy recommendations for improved sanitation system design, implementation, and operation and maintenance (O&M). This will allow decision-makers to make informed strategic decisions about sanitation systems and to accelerate the provision of collection and treatment services for used water and faecal sludge in South Asia. The goal of this master thesis will be to find out what level of (de)centralisation of sanitation systems is most cost effective and appropriate for typical urban and peri-urban Indian contexts. This will be studied on the example of 1-2 common types of sanitation systems.

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General approach The thesis will build on the work by Prof. Dr. Max Maurer and Dr. Sven Eggimann from Eawag as well as the work on costing done by Dr. Christoph Lüthi and his group at the Sandec department (also Eawag).

Tasks 1. Select 3-4 typical urban and peri-urban settings (neighbourhoods) to

compare. The settings should have different characteristic features (e.g. population density, water consumption)

2. Select 1-2 common types of wastewater treatment plant (WWTP) technology options for exemplary comparison

3. Develop the capital and operating costs of 4 different service options for each of the urban settings and selected technology options:

a. Connection to a centralised WWTP (data from implementers and infrastructure projects, e.g. ADB)

b. Connection to a small-scale WWTP at street level (or cluster of buildings)

c. Connection to a small-scale WWTP at building level

d. Faecal sludge management with an emptying service

4. Compare the service options for each of the urban settings based on costs

5. For the different urban settings, compare different scenarios (e.g. population density and growth, occupation rates, water reuse) and investigate the potential for modular systems.

Methods Costs can be assessed with different costing tools (e.g. Sandec’s BoQ-based costing tool, SaniPlan or based on a previous master thesis by Tobias Kraft (Matlab model)). Project framework: This master thesis is part of the ongoing 4S research project in India. More information under www.sandec.ch/4s Time: Starting April 2017 Advisors and Supervisors Professor: Prof. Dr. Max Maurer Supervisors Switzerland: Samuel Renggli, Philippe Reymond Supervisors India: Marius Klinger, Manas Rath, Karan Aswani

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Contact information Name: Samuel Renggli Email: [email protected] Phone: +41 58 765 5611 References:

S Eggimann, B Truffer, M Maurer - Water research, 2015; To connect or not to connect? Modelling the optimal degree of centralisation for wastewater infrastructures

S Eggimann, B Truffer, M Maurer - Water research, 2016; The cost of hybrid waste water systems: A systematic framework for specifying minimum cost-connection rates

S Eggimann, B Truffer, M Maurer - Water research, 2016; Economies of density for on-site waste water treatment

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Evaluating the mechanisms and performances of aerobic granular sludge for the treatment of municipal wastewater

Background Aerobic granular sludge (AGS) is a promising technology for the treatment of municipal wastewater (van Loosdrecht and Brdjanovic 2014) and an advancement over conventional activated sludge systems. Aerobic granules are dense aggregates with diameter larger than 250µm. A key advantage of AGS over conventional activated sludge systems is that simultaneous carbon/nitrogen/phosphorus removal can be achieved in a single reactor due to the existence of different redox zones within the granules. Additional advantages also include: fast settling velocity (i.e. easier separation between the treated water and the biomass), high biomass concentration and thus reduced reactor volume, and lower energy-demand. Energy reduction of 40 % and space savings up to 75% were reported recently ((Khan, Ahmad et al. 2015); (Rocktäschel, Klarmann et al. 2015)). Many studies performed at the laboratory-scale using synthetic wastewater helped to advance our understanding of AGS formation mechanisms. Several factors that influence granulation were identified: hydrodynamic shear force, feast–famine regime, feeding strategy, etc. However, very little information is available regarding the mechanisms and kinetics of granulation during treatment of real municipal wastewaters. Real municipal wastewaters indeed contain very little volatile fatty acids (VFA) and a large fraction of organic substrates in the particulate form (XS). Recent studies performed at Eawag suggested that the physical properties and performances of AGS fed with real municipal influent significantly differ from the ones of AGS fed with synthetic influent (Figure 1) (Derlon, Wagner et al. 2016). It is therefore crucial to evaluate the link between the influent composition, the microbial/physical structure and activity of AGS, and ultimately the operation and performances of AGS systems.

Figure 1: Picture of aerobic granular sludge cultivated with primary effluent wastewater (left) or with synthetic wastewater composed of volatile fatty acids (right).

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Objectives The main objective of the proposed master thesis is to evaluate how the wastewater composition in terms of VFA and XS content influences granulation, and ultimately the microbial/physical properties and performances (substrate conversion) of AGS systems. It is hypothesized that the concentrations in VFA and XS govern the granulation kinetic and in turn the physical properties of the AGS (settleability, ratio of flocs/granules, granule size, etc.). We also hypothesize that the type of organic substrates determines the extent of simultaneous nitrification/denitrification and thus the total nitrogen removal. The specific research questions to address during the master thesis are:

How do the VFA and XS contents of the wastewater influence the granulation process (kinetic of granule formation)?

How do the VFA and XS contents of the wastewater influence the physical properties of AGS (settling volume indexes, settling velocity, fraction of flocs vs. granules, etc.)?

How do the VFA and XS contents of the wastewater influence the distribution of microbial activities (between flocs and granules) and the overall substrate conversion (e.g. denitrification)?

Requirements Interests in technologies for biological wastewater treatment Interests in microbial processes applied to wastewater treatment Specific information This research will be performed in the department of Process Engineering at Eawag. Office space with computer and an existing experimental facility will be provided. This research is part of a joint project with Prof. Holliger (EPF Lausanne) funded by the Swiss National Foundation for Science (SNFS). Advisors Supervisor: Dr. Nicolas Derlon (Eawag) Advisor: Prof. Dr. Eberhard Morgenroth Contact information Name: Nicolas Derlon Email: [email protected] Phone: +41 (0)58 765 5378

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References Derlon, N., et al. (2016). "Formation of aerobic granules for the treatment of real and low-strength municipal wastewater using a sequencing batch reactor operated at constant volume." Water Research 105: 341-350. Khan, A. A., et al. (2015). "NEREDA: an emerging technology for sewage treatment." Water Practice & Technology 10(4): 799-805. Rocktäschel, T., et al. (2015). "Influence of the granulation grade on the concentration of suspended solids in the effluent of a pilot scale sequencing batch reactor operated with aerobic granular sludge." Separation and Purification Technology 142: 234-241. van Loosdrecht, M. C. M. and D. Brdjanovic (2014). "Anticipating the next century of wastewater treatment." Science 344(6191): 1452-1453.

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Soft-sensing of a urine nitrification reactor for nutrient recovery

Background The treatment of source-separated waste streams has been proposed as a new approach in environmental management. By means of separated handling and conversion of waste sources, one aims to recover valuable resources which are otherwise lost due to mixing and dilution with other waste streams. The biological urine nitrification process developed at Eawag is a promising implementation of this idea. With this process, the largest fraction of nitrogen and phosphorus in human excreta can be recovered as a fertilizer.

Top panels: Measured variables and measurements; Bottom panels: biomass and nitrogen concentrations and their estimated 99.9% confidence intervals. At all times, the provided confidence interval for nitrite includes the true state value. This however assumes that the model used for soft-sensing is equal to the monitored process. Unfortunately, the studied urine nitrification process is known to be unstable under high-load conditions. This is explained by the kinetics of the involved biological reactions. The nitrification process consists of two sequential biological reactions, ammonia oxidation and nitrite oxidation, executed by two distinct groups of bacteria, ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). The second group of bacteria uses nitrite as its substrate (reagent). Nitrite is however also toxic (reversibly inhibiting) to the NOB in moderate concentrations. Temporary accumulations of nitrite can lead to a complete stop of the nitrite oxidation step, eventually leading to a permanent presence of nitrite. This should be avoided since nitrite is toxic to crops and is thus not permitted to be present in the produced fertilizer. As such, it is essential to ensure that the first oxidation step is always the limiting reaction step in the chain of reactions.

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A further challenge is that currently available instruments do not permit a direct measurement of nitrite in nitrified urine. For this reason, soft-sensing of the nitrite concentration by means of a model-based observer or soft-sensor is an attractive option. This approach has led to positive results in simulation (see Figure below). The current soft-sensor however assumes that the simulated process and the model-based observer share the same model structure and parameters. Therefore, the robustness of the soft-sensor to deviations between model and reality is investigated in this study. Objectives of the suggested topic

Generate a number of scenarios which simulate toxic nitrite accumulations in the urine nitrification process.

Implement a simple control scheme which reduces the load when significant nitrite accumulations are detected.

Evaluate the robustness of model-based observer against model parameter deviations and model structure deficits.

Specific information / Requirements This project requires Matlab programming. Prior programming experience is not required however. Advisors and Supervisors Prof. Dr. Eberhard Morgenroth Dr. Kris Villez Christian Thürlimann Contact information Name: Kris Villez Email: [email protected] Phone: +41 (0)58 765 5280

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Monitoring wear-and-tear in pH sensors

Background Obtaining high quality data is critical to the monitoring, modelling, and automation of natural and engineered environmental processes. One example includes the monitoring of the biological urine nitrification process for the recovery of fertilizer from source-separated urine. In this process, controlling the pH is crucial to balance the conversion of ammonia to nitrite with the conversion of nitrite to nitrate. A failing pH measurement can lead to excessive ammonia loading which can cause nitrite accumulation and , if continued, inhibition and washout of the nitrite oxidizing bacteria. Successful process control therefore relies on reliable pH measurements.

Urine nitrification is used to test new monitoring and control concepts.

8 ISE sensors for pH are exposed continuously to the same medium.

Successful approaches to detect data of abnormal data quality rely on (i) redundancy (e.g. multiple sensors in the same location), (ii) mass balancing, or (iii) correlation-based data modelling. Despite these advances in the field, guaranteeing high quality data remains difficult. Most challenging are measurement errors caused by sensor signal drift. Drift is defined as a slowly changing measurement deviation. It is generally difficult to detect because of slow dynamics of drift, poor understanding of the causes of drift, and the simultaneous occurrence of drift in multiple sensors. For this reason, a study is under way to characterize the effects of sensor ageing in detail. Several ion-selective electrodes (ISE) for pH measurement are exposed to the same medium in order to cause the same wear-and-tear in all of them. Properties to be measured regularly include the offset, sensitivity, precision, and response

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time. It is of particular interest to know whether any of these properties can help to predict a complete failure of the sensor before it occurs (prognosis). At Eawag, we are the first in the world to collect such data in sensors exposed to wastewater media. In this study, the temporal variations of intercept, sensitivity, and response time are analyzed for the first time. Objectives of the suggested topic

Maintain a set of 8 ISE sensors for pH measurement. Evaluate the intercept, sensitivity, precision, and response time on a

regular basis for each of the sensors. Analyze the recorded sensor properties to evaluate whether significant

changes occur over time which can be related to the problem of drift. Specific information / Requirements This study requires some Matlab programming. Prior experience is not required however. The study includes routine application of sensor maintenance and testing protocols in laboratory conditions. Advisors and Supervisors Prof. Dr. Eberhard Morgenroth Dr. Kris Villez Marco Kipf Christian Thürlimann Dr. Kai Udert Contact information Name: Kris Villez Email: [email protected] Phone: +41 (0)58 765 5280

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Emissionsorientierte Erfolgskontrolle für besseren Gewässerschutz bei Regenwetter

Schüsselworte Gewässerschutz bei Regenwetter, Erfolgskontrolle, Emissionsorientiertes Monitoring, Integrierte Bewirtschaftung von Kanalisation, Kläranlage und Gewässer, Datenanalyse, Datenauswertung, Abwasserverband Region Baden Wettingen (ABW) Ausgangslage Bei Regenwetter wird häufig unbehandeltes Abwasser in unsere Gewässer eingeleitet, was diese zum Teil stark belastet. In den letzten Jahren wurden in der Schweiz bereits ca. 15-20% der Mischwasserbehandlungsanlagen mit Messtechnik instrumentiert und an das Prozessleitsystem (PLS) der Kläranlage angeschlossen. Damit sind vielerorts die Voraussetzungen gegeben, durch Analyse und Auswertung der hochaufgelösten Daten die Funktionsweise des Abwassersystems besser zu verstehen und eine emissionsorientierte Erfolgskontrolle durchzuführen. Dabei ist jedoch nicht klar, wie die komplexen Daten am besten für Betreiber und kantonale Behörden aufbereitet werden können. Ziel In dieser Arbeit sollen Grundlagen erarbeitet werden, wie die Messdaten eines Abwassersystems am besten für den Gewässerschutz bei Regenwetter eingesetzt werden können. Insbesondere soll untersucht werden, welcher Nutzen sich durch die Zusammenführung der Messdaten des PLS (Kanalnetz und ARA) mit frei verfügbaren Daten zu Klima, Niederschlag, Bevölkerung, Fliessgewässer, etc. erzielen lässt. Die Arbeit findet in enger Zusammenarbeit mit einer renommierten Privatunternehmung statt und wird am Beispiel des Abwasserverbandes Baden Wettingen (AG) durchgeführt. Die erzielten Ergebnisse sollen direkt in den Planungsprozess einfliessen.

Foto ARA Laufäcker und Einleitungsschema des ABW

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Das übergeordnete Ziel umfasst die folgenden Teilaufgaben:

Wissenschaftliche Auswertung der Entlastungs- und Entleerungsaktivität der Sonderbauwerke und der Kläranlage (Ereignis- und Gesamtauswertungen) und Defizitanalyse

Einbezug vorhandener Niederschlags- und Gewässerdaten zur Visualisierung der Entlastungsaktivitäten für grössere und kleinere Regenereignisse und Regentypen

Empfehlungen zur praktischen Erfolgskontrolle von Massnahmen, z.B. intelligente Bewirtschaftung von Kanalnetz und ARA (z.B. Kennzahlen, Visualisierungen)

Empfehlungen zur Ergänzung des ARA-Jahresbericht hinsichtlich Gewässerschutz bei Regenwetter

Aufzeigen des Handlungsbedarfes zur Reduktion von Gewässerbelastungen dank einer optimalen Ausnutzung der bestehenden Abwasserinfrastruktur

Ablauf Zur Erarbeitung der Aufgaben sind folgende Arbeitsschritte vorgesehen:

1. Grundlagenermittlung, Besprechung mit technischen Verantwortlichen Abwasserverband und Kanton

2. Sichtung der VGEP-Daten und Einleitungsschemata, der Messtechnik und PLS-Anbindung, der Labor- und Konzentrationswerte der ARA, der Messstellen für Niederschlag, Fliessgewässer und evtl. Grundwasser

3. Konzeptionelle und technische Erfassung der vorhandenen Entwässerungsinfrastruktur und der vorhandenen Datengrundlagen

4. Begehung des ARA-Einzugsgebietes, Besichtigung und Erfassung der relevanten Behandlungsanlagen, Entlastungsstellen ins Gewässer und der Messtechnik

5. Wissenschaftliche Analyse, Datenprüfung und praxisorientierte Auswertung aller relevanten, historischen Messdaten aus dem Prozessleitsystem der ARA, Konzentrations- und Frachtwerten, Niederschlags- und Wasserstandwerten. Konzeptionelle Überlegungen und technische Generierung möglichst unterschiedlicher Messwertdarstellungen einzeln und in Kombination sowie für einzelne Behandlungsanlagen und im Verbund (ergänzend Einzelereignis- und Gesamtauswertungen).

6. Entwicklung von griffigen und vielseitigen Auswerteroutinen für PLS-Daten für Betreiber, Überwachungsbehörden, Politiker etc. Ermittlung und Bewertung der Leistungsfähigkeit der Regenwasserbewirtschaftung: i) Füllungs-, Entlastungs- und Entleerungsverhalten, ii) ARA-Kapazitäts-und Leistungsfähigkeitsauswertungen, iii) Niederschlagsereignissen-, -typen- versus Entlastungsauswertungen, iv) Fliessgewässerstands- versus Entlastungsauswertungen etc.

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7. Empfehlung für Minimalstandard und optionale Visualisierungen und Auswertungen zum emissionsorientierten Monitoring zwecks Diskussion zur zukünftigen Integration in die ARA-Jahresberichte.

8. Diskussion der Ergebnisse und Vergleich mit immissionorientierter (Event-) Erfolgskontrolle, und Planungshilfen (STORM-Richtlinien, GEP Musterpflichtenhefte etc.)

9. Aufzeigen des (generellen und individuellen) Handlungsbedarfs aus den erzielten Erkenntnissen für Abwasserverband

10. Präsentation und Diskussion der Ergebnisse mit Verantwortlichen der Kantonalen Fachstellen und der Abwasserverbände.

11. Aufbereitung und Dokumentation der erzielten Resultate Voraussetzungen

Interesse an Urbanhydrologie, Genereller Entwässerungsplanung, Kläranlagenauslegung, Verfahrensoptimierung, Kanalnetzbewirtschaftung und modernem Gewässerschutz

Interesse an technischen Fertigkeiten zur rechnergestützen Datenanalyse

Interesse an angewandter Wissenschaft und Zusammenarbeit mit Praxispartnern

Programmierkenntnisse (Matlab, R etc.) sind von grossem Vorteil Kenntnisse zu hydrologischen Berechnungsprogrammen (City

Drain, SWMM, etc.) und Langzeitseriensimulationen sind von Vorteil Flair für visuelles Gestalten ist von Vorteil Genaues Arbeiten, hohe Motivation, Innovation und Initiative sowie

Bereitschaft zu interdisziplinärem Denken Termine, Dauer

Die Masterarbeit kann ab Februar 2017 beginnen, bzw. in gegenseitiger Absprache

Die Masterarbeit dauert 18 Wochen Es sind regelmässige Zwischenbesprechungen mit den Betreuern

vorgesehen (ca. 5-7) Betreuung Dr. Jörg Rieckermann, Eawag Michael Brögli und Gian Levy, HOLINGER AG Prof. Max Maurer, ETHZ und Eawag Kontakt Name: Jörg Rieckermann Email: joerg.rieckermann @eawag.ch Telefon: +41 (0)58 765 5397

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Evaluation of Membrane Integrity for Potable Water and Grey Water treatment

Ultrafiltration membrane technology is a focus of research at Eawag for treatment of potable water (e.g. household water filter Safir), and grey water treatment and recycling (SELF, NEST, Blue Diversion – Water Wall). Most of these processes are based on so-called gravity-driven membranes (GDM), a technology that allows a biofilm to be formed on the membrane and leads to stabilization of flux.

The measurement of membrane integrity is important for these applications, not only to verify the intactness of membranes before operation, but also during operation in order to check if mechanical or cleaning processes have damaged the membrane. In order to analyze membrane integrity, many different methods have been described in literature including direct and indirect measurements. In order to evaluate removal of pathogens, the most relevant information is derived from methods that detect the passage of pathogens or surrogates that resemble the structure and properties of pathogens. In preceding investigations, methods for integrity analysis have been developed using relatively harmless bacteria (Enterococcen) and non-pathogenic viruses (MS2 phage). Surprising results have been obtained in the comparison different membranes: it was shown that the pore size indicated by the manufacturer was not a reliable indicator of integrity. In comparison, some membranes showed a higher rejection for bacteria but a lower rejection for MS2, which is an indication for differences in pore size distribution or can even imply that defects (“pinholes”) may be present in certain types of membranes. Furthermore, it was shown that the presence of a biofilm on the membrane can impact the retention substantially. The MSc thesis focuses one hand on the continuation of these investigations to evaluate integrity of different membranes and the influence of operating parameters and biofilm presence. On the other hand, new methods need to be developed for measurement of integrity during system operation (“in situ”). For such purposes new surrogates needs to be identified and tested, both under lab conditions and in systems in operation for treatment of grey water and potable

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water. For this purpose, a close collaboration with the research groups working on GDM and on grey water treatment is foreseen. Advisors Prof. Dr. Eberhard Morgenroth Dr. Wouter Pronk Contact information Name: Wouter Pronk

Eawag, Process Engineering Department Email: [email protected]

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Low-pressure Membranes (GDM) as a Pretreatment of Reverse Osmosis for the Desalination of Seawater in Singapore

Reverse Osmosis (RO) is a generally used technology for the desalination of seawater. In order to prevent clogging of RO elements, an extensive pretreatment is required. In recent years, Ultrafiltration (UF) has increasingly been investigated and applied as main step in the pretreatment. However, conventional UF is associated with a relatively high consumption of energy and chemicals for membrane cleaning. An alternative, more sustainable approach consists of gravity driven ultrafiltration membranes (GDM), whereby low pressures are used and no chemical cleaning is required (1). A successful collaboration has been built up between the Singapore Membrane Technology Center (SMTC), Eawag and HSR (Hochschule Rapperswil) in order to further investigate and develop GDM technology for seawater pretreatment (2, 3). Investigations so far have shown that this technology is feasible and flux stabilization occurs without any membrane flushing or cleaning. Recently, a pilot plant based has been constructed at RO facilities in Singapore, where seawater is treated by the GDM principle using two types of membranes (hollow fiber and flat sheet).

The MSc Thesis will investigate the effect of retention time on the flux and focus on the general optimization of the system in the lab and pilot plant. The role of the microbial community and the fate of organics are important aspects which need to be considered. Furthermore, these results will be used for the dimensioning of a full-scale pretreatment plant. This includes configuration of membrane modules and estimation of investment costs and operation costs. The work will be carried out at and directly supervised by the SMTC in Singapore, while general supervision and background knowledge on GDM is provided by Wouter Pronk (Eawag).

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Advisors Prof. Dr. Eberhard Morgenroth Dr. Wouter Pronk Dr. Bing Wu (NTNU) Contact information Name: Wouter Pronk

Eawag, Process Engineering Department Email: [email protected] References 1. M. Peter-Varbanets, F. Hammes, M. Vital, W. Pronk, Stabilization of flux

during dead-end ultra-low pressure ultrafiltration. Water Research 44, 3607-3616 (2010); published online EpubJun (10.1016/j.watres.2010.04.020).

2. E. Akhondi, B. Wu, S. Sun, B. Marxer, W. Lim, J. Gu, L. Liu, M. Burkhardt, D. McDougald, W. Pronk, A. G. Fane, Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: Linking biofouling layer morphology with flux stabilization. Water Research 70, 158-173 (2015); published online Epub3/1/ (http://dx.doi.org/10.1016/j.watres.2014.12.001).

3. B. Wu, F. Hochstrasser, E. Akhondi, N. Ambauen, L. Tschirren, M. Burkhardt, A. G. Fane, W. Pronk, Optimization of gravity-driven membrane (GDM) filtration process for seawater pretreatment. Water research 93, 133-140 (2016); published online Epub2016-Apr-15 (10.1016/j.watres.2016.02.021).

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Laboratory investigation of physical disintegration of gross solids in the sewer

Background Investigation of the phenomena in sewer systems are critical for increasing the sustainability of these systems and the efficiency in their operation. Among the numerous phenomena in these systems are gross solids transport. Gross solids are usually defined as solids bigger than 6mm in two dimensions (i.e. captured by a 6mm mesh screen). Their specific gravity is usually in the range of 0.9-1.2 and they include faecal stools, toilet paper and “sanitary refuse” such as women’s sanitary protection, condoms, bathroom litter, etc. Gross solids are of particular concern for sewer systems since they can cause maintenance problems such as blockages and their sedimentation can increase the formation of toxic gasses (e.g., Sulphide and Methane), they can further cause blinding of screens at waste water treatment plants. Reduction in wastewater discharges (as a result of e.g., steep population decrease and/or implementation of domestic water saving measures), results in lower flow velocities in sewer stretches which is expected to increase the impacts of faecal matter and other gross solids material. Goal In the proposed Master research, we aim at quantifying gross solids’, specifically faecals, physical disintegration under realistic hydrodynamic conditions. Based on the experimental data we will devise a model which will constitute a module in a simulation, aiming at assessing the effects of reduction in domestic water consumption and transition to decentralized wastewater treatment systems on the operation of sewer systems. Objective and suggested tasks The objective is:

1. Characterize physical disintegration of gross solids in different turbulent conditions.

The research will consist of three main steps: Lab experiments for determination of synthetic (odor less) faecals’

physical disintegration under hydrodynamic stress varying the intensity of the turbulence. The turbulent flow will be realized in a reactor. Synthetic faecals will be produced from a receipt, altering quantities of components. An automated PTV technique (Particle Tracking Velocimetry) with the use of cameras will enable to characterize the particle size distribution over time, i.e. the physical disintegration of the synthetic faecals.

Image analysis of the images obtained from the experiments. Verification of the findings found in the previous step, by repeating the

experiments with real faecals – this step will be conducted under well-defined and safe conditions.

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Requirements Interest in sewer hydraulics and fluid mechanics Comprehensive knowledge in Matlab - required, image analysis -

advantage High motivation and initiative

Timing and schedule The thesis starts immediately, resp. in agreement with the involved

parties The duration is 16 weeks Meetings with the advisors are scheduled frequently, e.g. weekly or bi-

weekly, whereas there are two meetings with the supervisor.

Supervision Advisors: Dr. Roni Penn, Eawag

Supervisors: Prof. Dr. Markus Holzner, ETH Zürich Prof. Dr. Max Maurer, ETH Zürich and Eawag

Contact information Name: Roni Penn Email: [email protected] Phone: +41 (0)58 765 5012

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Stabilizing urine nitrification as a pretreatment for fertilizer production: development, test and evaluation of novel control concept

Background Nutrient recovery from source separated urine is a promising technology to move wastewater collection and treatment into a more sustainable future. One process chain to recover nutrient includes the biological nitrification of urine in order to stabilise the nitrogen content (Udert and Wächter, 2012). Under varying urine loads, the nitrification process accumulates nitrite on a regular basis. Without fast human interference, these accumulations lead to irreversible inhibition of the nitrite oxidizing bacteria within days and normally requires a complete new start-up of the reactor. Within the SoDAN (Soft-Sensing, Diagnosis and Automation for Nutrient Recovery) project, we aim to implement a control strategy to prevent these accumulations automatically under fluctuating inflow schemes.

Figure 1: Urine nitrification reactor.

With in-situ ultraviolet and visible light (UV-Vis) spectrometry we are able to detect nitrite in urine (Masic et al., 2015). However, we expect that the sensor lacks of absolute accuracy and only qualitatively follows the nitrite concentration in the reactor. Therefore we hypothesis that a dynamic operation of the reactor is needed to obtain an information rich signal which allows stabilising the process.

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Objectives of the suggested topic The goal of this master thesis is to evaluate this dynamic and potentially stabilising operation of the reactor with regards to the following challenges:

a. Confirmation of the qualitative nature of the UV-Vis based nitrite signal, by measurement campaigns.

b. Offline application of data analysis techniques to extract the relevant qualitative information from the signal to control the reactor loading.

c. Test the develop data analysis techniques online and challenge the reactor with artificial induced disruption.

d. Evaluate the control concept with regards to nitrogen conversion performance, N2O production etc.

Specific information This thesis involves apart from the close supervision of the reactor including laboratory measurements also PC-based analysis in the office. This research will be performed in the department of Process Engineering at Eawag in Dübendorf. Office space with computer and an existing urine nitrification reactor will be provided. For the data processing Matlab will be used. References Udert, K.M., Wächter, M. Complete nutrient recovery from source-separated urine by nitrification and distillation (2012) Water Research, 46, pp. 453-464. Mašić, A., Santos, A.T.L., Etter, B., Udert, K.M., Villez, K. Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry (2015) Water Research, 85, pp. 244-254. Advisors Prof. Dr. Eberhard Morgenroth Dr. Kris Villez (Eawag) Christian Thürlimann (Eawag) Contact information Name: Kris Villez Email: [email protected] Phone: +41 (0)58 765 5280

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What is the impact of heavy rainfalls on a potential river contamination by engineered nanomaterials? Background Although wastewater treatment plants (WWTP) have a very high removal efficiency concerning engineered nanomaterials (ENMs), occasional heavy rainfalls (storm events), during which the wastewater bypasses the WWTPs, may compromise the operational efficiency of WWTPs in Switzerland. Thus, we will investigate to what extent ENMs entering the surface water during storm events contribute to the overall ENMs budget of WWTPs in Switzerland.

Objectives of the suggested topic

1. Literature study on urban sources, removal efficiency on WWTP and selection of relevant, engineered nanomaterials.

2. Developing a stochastic model for predicting the emissions of ENMs during storm events (geographically resolved on a river section level).

3. Collecting and analyzing data to assess the expected wastewater treatment efficiencies as well as the annual direct discharges (bypasses) during heavy rainfall events.

4. Performing a model sensitivity analysis to evaluate the annual contribution of storm events to the total emission budget of ENMs.

Addressing these main objectives will lead to the development of a generalized model to asses untreated, direct discharges of ENMs. The particular challenge of this work will be collecting empirical information as well as unraveling the frequency and predictability of storm event based emissions of ENMs. Specific information This project will be performed in the department of Urban Water Management at Eawag in collaboration with ETSS. Office space with computer will be provided. Requirements Affinity to modeling and system analysis (programming environment R). Basic knowledge of GIS is an asset.

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Advisors Prof. Dr. Max Maurer Dr. Fadri Gottschalk (ETSS AG) Dr. Christoph Ort (Eawag) Dr. Ralf Kägi (Eawag) Lena Mutzner (Eawag) Contact information Name: Dr. Fadri Gottschalk Email: [email protected] Phone: +41 (0)81 860 1085 Name: Lena Mutzner Email: [email protected] Phone: +41 (0)58 765 5929

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Obtaining Sludge Settling Properties via Image Analysis

Background Secondary clarifiers are a key element of the activated sludge process for biological wastewater treatment. By providing both clarifying and thickening functions, a secondary clarifier ensure adequate effluent quality while ensuring efficient and stable operation in the long term [1]. Unfortunately, the performance of secondary settling tanks in conventional biological wastewater treatment systems is difficult to predict under realistic conditions. As a result, monitoring and optimal operation of settlers is challenging in practice. This leads to losses in efficiency which could be prevented by applying novel monitoring and modelling concepts. Most commonly, sludge settler operation is based on modelling of the sludge settling flux curve by means of correlation with measurement of the sludge volume index (SVI) [2]. More advanced and presumably accurate methods are based on empirical modelling of the sludge settling velocity as a function of the sludge concentration [3]. It remains a challenge however to collect empirical data to the point that online updating of the settling velocity function is possible and settler performance monitoring becomes practical [4]. At Eawag, a novel method to register the sludge blanket during batch settling experiments has been developed. Each of such batch settling experiments leads to an estimate for the sludge settling velocity at a single sludge concentration. By means of repeated batch experiments following sample concentration and dilution the sludge settling velocity curve can be obtained and modelled. Currently available results have been obtained for a granular sludge reactor at Eawag. In this project, the effects of variations of the batch settling experiments will be investigated. Such variations relate to the mixing conditions (e.g., with or without mixing) and the sampling method (e.g., bucket, gravity, or pumping). Objectives of the suggested topic

1. Experimental evaluation of the effect of mixing conditions and sampling methods on the obtained sludge blanket measurements, sludge settling velocity, and sludge settling flux curves.

2. Test the robustness of the available image analysis software (Matlab) against visual reference readings of the sludge blanket height.

3. Evaluate the experimental and image analysis methods with different wastewaters, sampled at different wastewater treatment plants and at different times.

Specific information Experiments and modelling tasks are executed at Eawag and at different WWTPs in the Zürich area. For experimentation, all hardware will be provided. For data analysis and modelling, the Matlab environment will be used.

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References [1] Henze, M.; van Loosdrecht, M. C. M. ; Ekama, G. A. ; Brdjanovic, D. (2008).

Biological wastewater treatment: Principles, modelling and design. IWA Publishing.

[2] Daigger, G. T. ; Roper Jr, R. E. (1985). The relationship between SVI and activated sludge settling characteristics. Journal (Water Pollution Control Federation), 57(8), 859-866.

[3] Ramin, E. ; Wágner, D. S. ; Yde, L. ; Binning, P. J. ; Rasmussen, M. R. ; Mikkelsen, P. S. ; Plósz, B. G. (2014). A new settling velocity model to describe secondary sedimentation. Water Research, 66, 447-458.

[4] Plosz, B.G.; Nopens, I., Rieger, L. ; Griborio, A. ; De Clercq, J. ; Vanrolleghem, P.A. ; Daigger, G.T., Takacs, I. ; Wicks, J. ; Ekama, G.A., 2012. A critical review of clarifier modelling: State-of-the-art and engineering practices. Proceedings of the 3rd IWA/WEF Wastewater Treatment Modelling Seminar (WWTmod2012), Mont-Sainte-Anne, Quebec, Canada.

Advisors Professor Dr. Eberhard Morgenroth Kris Villez (Eawag) Contact information Name: Kris Villez Email: [email protected] Phone: +41 (0)58 765 5280

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Growth of microorganisms in treated grey water as part of Blue Diversion AUTARKY project

Background and Objectives Blue Diversion AUTARKY toilet (BDT, http://www.bluediversiontoilet.com/, Figure 1) developed at EAWAG is a source separating toilet developed as part of the Reinvent the Toilet challenge from the Bill and Melinda Gates Foundation. The BDT has urine and feces separately collected and treated for resource recovery. The goal of the toilet is to provide a safe and affordable sanitation technology for the billions of people who lack of access. Toilet flushing, hand washing and personal hygiene water are treated and recycled within the system. A biologically activated membrane bioreactor (BAMBi) has been employed as primary treatment to efficiently remove organic materials and nitrogen from toilet wastewater. We are currently evaluating state-of-art post treatment technologies, including ozone, electrolysis, UV, and granular activated carbon (GAC) for polishing primary treated wastewater to reach safe level for hand washing and personal cleansing. The choice of post treatment technologies is based on their performance in treating the remaining organic materials and inactivating (and/or removing) pathogens with consideration of energy and cost efficiency. Additionally, regrowth of pathogens is considered as one of the criteria for the best post treatment technology due to the possibility of pathogen regrowth within the storage tank of post-treated water. The goal of this project is to ensure the safety of grey water use for hand hygiene. The student will specifically evaluate the growth potential of fecal bacteria (used as indicators for bacterial pathogens) in water within the toilet after each post treatment technology listed above. Results of this project will be used to choose the final post treatment technology for the BDT.

Figure 1: Picture of Blue Diversion prototype toilets installed in an existing structure.

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Project description We are looking for a highly motivated Master’s student to study the growth potential of two fecal indicator bacteria Escherichia coli and Enterococcus faecalis in water from the BDT. The Master thesis will provide answers for three main research questions: 1. Can the bacteria grow in water within the BDT? 2. Does the bacterial growth depend on water characteristics? 3. Can the bacterial growth be inhibited by adjusting water characteristics? The Master’s student will use culture and molecular based methods to quantify the growth potential of the bacteria. (More information of growth potential bioassay can be found in Vital et al. (2010).) The thesis will include discussion on how different post treatment technologies influence the growth potential of the bacteria. Results will be integrated into the ongoing developments of the BDT. Reference Vital, M., Stucki, D., Egli, T. & Hammes, F. Evaluating the growth potential of pathogenic bacteria in water. Appl. Environ. Microbiol. 76, 6477–6484 (2010). Additional information Work will be performed in collaboration with the Pathogens and Human Health research group at Eawag (Dübendorf). Further information about our facilities and approaches are provided at http://www.eawag.ch/forschung/eng/index_EN Further information about the Blue Diversion AUTARKY Project is available at http://forum.susana.org/forum/categories/106-user-interface-technology-innovations/13529-blue-diversion-autarky-a-self-sustaining-toilet-off-the-grid-eawag-switzerland http://www.bluediversiontoilet.com/ Advisors Prof. Dr. Eberhard Morgenroth Dr. Mi Nguyen Dr. Tim Julian Contact information Name: Mi Nguyen Email: [email protected]

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How does urbanization influence groundwater recharge of alluvial aquifers?

Background and Objectives Alluvial aquifers are a main source of drinking water in Switzerland but under pressure by increasing urbanization and intense agriculture. It is often assumed that urbanization leads to a decrease in groundwater recharge due to sealing of surfaces and as a consequence to a lower groundwater availability. In comparison, recharge rates are expected to be higher in agricultural areas. These assumptions are however rarely challenged and verified, and the opposite might actually be true. Current urban drainage rules require infiltration of clean meteoric water into the subsurface wherever possible, which might lead to an increase rather than a decrease in recharge. In reverse, intense agriculture could reduce recharge due to tile drainage, soil compaction, and stronger evapotranspiration associated with crops. The cultivation of intermediate crops to reduce nitrate loss to groundwater can further decrease recharge due to higher evapotranspiration as indicated by lysimeter studies. The objective of the Master thesis is to contribute “facts” to this groundwater recharge debate and to challenge common views on how recharge is related to land use based on a case study. Possible research approach and methods The study will focus on a well-characterized alluvial aquifer that has seen rapid urbanization but still contains large zones with intense agriculture, the Gäu aquifer between Oensingen and Olten. The following research approach could be used:

‐ Development of conceptual models/schemes of how urban areas influence groundwater recharge

‐ Establishment of water balances for agricultural and urbanized zones using existing data and complementary field measurements

‐ Comparison of older and more recently urbanized areas to evaluate how different urban drainage approaches influence the water balance and groundwater recharge

‐ Integration of study results into existing water balances of the entire aquifer to evaluate how strongly urbanization influences the overall groundwater dynamics

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Research partners As the study relies on knowledge from urban water systems as well as hydrogeology, it will be carried out in close collaboration between the Urban Water Management Laboratory of the ETHZ (Prof. M. Maurer) and the CHYN (Prof. D.Hunkeler). Advisors Prof. Dr. Max Maurer (ETH Zürich, Eawag) Prof. Dr. Daniel Hunkeler (Université de Neuchâtel, Centre d’hydrogéologie) Contact information Name: Prof. Dr. Daniel Hunkeler Email: [email protected] Phone: +41 (0)32 718 2560

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Overland Flow Network delineation allowing for flow divergence

Keywords: Digital Elevation Model, flow momentum and divergence, overland flow network, raster analysis Overland flow models require good 1D overland flow representation! High-intensity rainfall events can generate flooding in urban areas, which in turn cause serious social (e.g. injuries), economical and infrastructural damages. It is therefore desirable to have accurate flood predictions (flood extent and water depth). Current research in urban flood modeling is generally focused into the area of 1D/2D modeling: the coupling of one-dimensional (1D) hydrodynamic models of the sewer system with two-dimensional (2D) overland flow models. While 1D/2D models generate more accurate flood predictions, they come at the cost of a computation time when compared to the alternative 1D/1D flood model - a prohibitive price for Swiss engineering companies. One of the main strengths of 2D overland flow models over current 1D overland flow models is the faithful representation of diverging flow paths, a task that is currently impossible for 1D models due to the complexity of delineating flow paths over a DEM. Objectives The main goal of this thesis is to develop a novel 1D overland flow path delineation method able to take into account flow divergence. The new method should be based on the aspect driven kinematic routing algorithm presented by Lea (1992). This algorithm, also known as the “rolling ball algorithm”, uses the aspect raster to delineate flow paths. Flow paths delineated using the new method should be compared and assessed towards the results obtained using other available 1D overland flow network generators (see Wilson et al. (2008) for different 1D overland flow network generation algorithms). The new method should delineate preferential flow paths as well as secondary flow paths that only appear at higher flow regimes. The method should represent divergent flow in a way that is compatible with the EPA StormWater Management Model (SWWM) (Rossman, 2007). Suggested tasks

1. Literature review on overland flow, urban drainage modelling, and input data requirements;

2. Development of a novel method to generate 1D overland flow networks that takes into account flow divergence (and flow momentum);

3. Comparison of the obtained overland network using the proposed method with networks obtained using other algorithms, on the basis of a field test, e.g. in Adliswil;

4. Discussion of the obtained results, with a special focus on usability of

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the proposed method to improve 1D overland flow/ flood modelling in urban areas.

Requirements

Interest in urban hydrology and hydrodynamic modelling; Computer programming skills; Good knowledge of English; Basic knowledge of GIS is an asset; A good amount of motivation and initiative

Advisors Dr. João P. Leitão (Eawag) Prof. Dr. Max Maurer (ETH Zürich, Eawag) Contact information Name: João P. Leitão Email: [email protected] Phone: +41 (0)58 765 6714

References Lea, N.L., (1992), An aspect driven kinematic routing algorithm. In Parsons, A.J., Abrahams, A.D. (eds.): Overland Flow: Hydraulics and Erosion Mechanics, UCL Press, London, UK, 393–407.

Rossman, L.A. (2007). Storm Water Management Model User’s Manual, EPA/600/R-05/040, U.S. Environmental Protection Agency, Cincinnati, OH, USA.

Wilson, J.P., Aggett, G., Yongxin, D., Lam, C.S. (2008). Water in the landscape: a review of contemporary flow routing algorithms. In Zhou, Q., Lees, B., Tang, G. (Eds.), Advances in Digital Terrain Analysis, Springer, New York, USA, 213–236.

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Dynamic Control and Monitoring of the Waste Water Treatment Process

Background Dynamic adaption of the control parameter from a WWTP to the load in the influent has the potential to optimize the effluent quality and/or the cleaning capacity. Dynamic control strategies have to be on the one hand robust to all kinds of disturbances and should on the other hand guarantee a good cleaning performance. This requires a monitoring strategy of the operating data, which reflects the dynamic changes of the influent and the operational parameters in an intuitive way to empower the operator and the consulting engineers to supervise the WWTP and adapt the given parameters of the control loops. The Laboratory for Environmental Engineering has developed the Software SeNARA (Sensor Netzwerk für Abwasserreinigungsanlagen) as a platform to develop methods for supervising control strategies. In addition the project proposal which deals with dynamic control strategies (Dynamische Regelung und Prozessüberwachung in der Abwasserreinigung) has been accepted from VSA. Case study ARA Schönau The operational data of the ARA Schönau are analyzed to access the potential of dynamic control strategies. Additional measurement campaigns are conduced to get more information about the dynamic behavior of the WWTP. The student will compare new control strategies and analyze them with numerical simulations and optionally with test measurements. The thesis is a part of the project SeNARA (Sensor Netzwerk für die Abwasserreinigung). It is intended to implement results of the master thesis in the existing project. Tasks:

1. Analyzing the operational data of the last two years. 2. Estimation the effects of the asymmetric distribution of the waste water

from the five aerobic streets on the effluent quality and the cleaning capacity.

3. Simplified dynamic simulation to predict the efficiency of different control strategies (Matlab, Berkley-Madonna, ASIM).

4. Proposal for optimization of nitrification and bioP. 5. Prediction of load limits. 6. Eventually experiments on the WWTP to validate model assumptions

and effects of control strategies.

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Prerequisite The student will have direct contact to operators of waste water treatment plants; therefore the student should speak German. Experience with Matlab is advisable. Specific information The work place of the student is in the HIF building on the Hönggerberg. Advisors Luzia von Känel, Daniel Braun (ETH Zürich, Laboratory for Environmental Engineering) Prof. Dr. Eberhard Morgenroth / Prof. Dr. Max Maurer (ETH Zürich, Eawag) Contact information Name: Daniel Braun Email: [email protected] Phone: +41 (0) 44 633 2454

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Amine-containing micropollutants – Modeling their pH-dependent uptake and biotransformation in sludge bacteria

Keywords Model prediction, micropollutant, biotransformation, bioavailability, activated sludge Background Many micropollutant entering wastewater treatment plants contain an amine-functional group. They are therefore partially positively charged, depending on pH. In a series of experiments with activated sludge performed at different pH, we found that the biotransformation of amine-containing compounds increases with increasing pH. Thus, pH is potentially an important factor to understand and predict differences in removal performance for basic and acidic micropollutants between different wastewater treatment plants. Our results indicate a qualitative correlation with the degree of speciation, but the extent of observed pH-dependence was lower than predicted by a simple speciation model only. Several mechanisms could potentially be responsible for the observed attenuation of pH-dependence. Their relative contribution needs to be better understood to quantitatively account for pH-dependent removal of speciating micropollutants. Objectives The aim of this thesis is to explore different plausible mechanisms for pH-dependent biotransformation by encoding them into a basic model of cellular uptake and enzymatic transformation of speciating micropollutants and comparison of the results to our measured data. The suggested tasks are as follows:

1. Gain an overview over the different plausible mechanisms for attenuation of pH-dependence based on the scientific literature.

2. Encode a published dynamic model to estimate bioavailability and steady-state accumulation in bacterial cells in R.

3. Extend the model with the different mechanisms for attenuation of pH-dependence and compare the predicted pH dependence with the observed pH dependence, including a quantitative assessment of the uncertainty of the model predictions. Can any mechanisms be excluded based on this comparison? What mechanisms emerge as most likely mechanisms?

4. Derive suggestions for future experiments to further test the hypothesized mechanisms.

5. Documentation of the obtained results.

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Requirements ‐ Interest in modeling of biological systems and fate of micropollutants

during wastewater treatment ‐ Good programming skills (currently, a prototype of the approach is

implemented in R) ‐ Good knowledge of English ‐ A good amount of motivation and initiative

Supervisors Dr. Kathrin Fenner, Eawag and University Zurich Prof. Dr. Eberhard Morgenroth, Eawag and ETHZ D-BAUG Contact information Name: Dr. Kathrin Fenner. Eawag Email: [email protected] Phone: +41 (0)58 765 5085

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Automatic correction of systematic errors of rainfall-runoff models

Keywords Run-off predictions, Bayesian, data mining, model calibration, Gaussian process Rainfall-runoff modeling – physically-based vs. data mining approaches Traditionally, run-off predictions are computed with deterministic models which are based on physical principles. Unfortunately, such models can never capture all processes exactly, for example because they miss relevant processes such as evaporation, or due to equations that cannot represent a process perfectly. This might lead to systematic deviations (bias) in the model predictions. On the other hand, physically-based models are capable to extrapolate, i.e. to produce reasonable predictions for extreme rainfall events that are larger than those in the observed data used for calibration. In contrast, models based on data mining/artificial intelligence techniques such as regression, neuronal networks, or tree based models, are purely data driven and contain no process knowledge. Although such black-box models often produce very accurate predictions within the range of the observed data, prediction for extreme events, where the model has to extrapolate, can be very poor as no physical laws as “guidance” exist.

Figure 1: Bias correction with Gaussian processes for a toy example. The corrected predictions (grey) follow the data (blue) much better than the deterministic model alone (green).

In hydrology Gaussian processes (GP’s) are sometimes used to represent the error term (bias) of deterministic models. In data mining, however, GP’s are applied completely different: as data driven, non-linear regression models (that includes many neural networks as special cases). Bases on this two applica-tions of GP’s, a recently at Eawag developed approach tries to combine the

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strength of both modeling approaches: the predictions are based on a physically-based model whose bias is corrected by a data driven model. This correction only applies within the observed data so that extrapolation of the data driven model is avoided. Objectives The aim of this thesis is to investigate the potential of the automatic model bias correction for hydrological models. The suggested tasks are as follows:

1. Gain a basic understand of the new model bias correction approach

with some didactical examples 2. Create synthetic data sets with a complex model (e.g. implemented

in the hydrodynamic simulator SWMM) that serves as test cases for the calibration and correction.

3. Calibrate a simpler model on the synthetic data sets. How far can the ‘bias correction” compensate for the simpler model structure? What kind of model biases are corrected best?

4. Assessing the predictive performance with cross-validation. 5. Optionally, calibrate a model on real precipitation and run-off data. 6. Assessing the applicability of the approach with regard to

hydrological modeling. 7. Documentation of the obtained results.

Requirements

Interest in model calibration techniques, probabilities and statistics Good programming skills (currently, a prototype of the approach is

implemented in R) Good knowledge of English A good amount of motivation and initiative

Supervison Andreas Scheidegger, Eawag Dr. Jörg Rieckermann, Eawag Prof. Max Maurer, ETHZ and Eawag Contact information Name: Andreas Scheidegger Email: [email protected] Phone: +41 (0)58 765 5053

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Calibrating urban inundation models using novel information from social media

Keywords Urban flood modeling, water level information, facebook, twitter, flickr Accurate urban flood models need good output data Urban floods can happen in a relatively short period of time and can inundate large areas with significant water depths. Ongoing urbanization and increase of heavy rainfall events, e.g. from climate change, increase flood risks in cities. As economic damages of urban flooding are usually high, especially in city centers, it would be desirable to have accurate predictions of flood zones. Recent developments in flood modeling suggest that coupled (1D/2D) one-dimensional (1D) hydrodynamic models for sewer pipe network systems and two-dimensional (2D) surface flow models predicts urban inundation more accurately than traditional 1D/1D models. Unfortunately, as such floods only occur very locally with minutes to hours, it is virtually impossible to obtain the required surface water level data in flooded areas to calibrate such models. Objectives The goal of this thesis is to investigate how far information obtained from social media, such as facebook, twitter, flickr can provide local information on urban floods. This can also include other relevant data sources such as webcams or newspaper archives. Possible approaches could be to search and download the data, such as text, images or videos, using the provided Web APIs or use web-scarping services such as ScraperWiki. To identify the relevant content a classification based on meta-data such as coordinates, time, tags and EXIF date could be applied. Similarly, time and street names could be scraped for posts on twitter or facebook. Flood images or videos most probably still require

a manual assessment of the water level or spread however, a good pre-selection could minimize this effort considerably.

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The suggested tasks are as follows:

1. Revision of literature on surface flood modeling and data requirements on

urban flooding; 2. Literature study on possible social media sources and ways to extract relevant

information (APIs) for surface flood model calibration; 3. Investigation of data type and meta-data (e.g. date, local, coordinates, etc.),

quality and completeness: how far can social media data contain information to urban flood modeling?

4. Testing and implementation of a proof-of-concept: generation of a spatio-temporal dataset, e.g. of flood zones or water levels.

5. Assessing the results with regard to urban flood modeling. For example: which is more useful, water table information or the extent of flooded areas? Are flood levels with an accuracy of 1-2 m still useful for urban drainage?

6. Documentation of the obtained results Requirements

Good computer programming skills (Python, Ruby, R) Good knowledge of English Interest in social media analysis and urban hydrology A good amount of motivation and initiative Basic knowledge of Web API programming and GIS is an asset

Supervison Dr. Jörg Rieckermann, Eawag Dr. João P. Leitão, Eawag Andreas Scheidegger, Eawag Prof. Max Maurer, ETHZ and Eawag Contact information Name: Jörg Rieckemann Email: [email protected] Phone: +41 (0)58 765 5397

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Evaluating the influence of hydrolysis on the quality of drinking water produced during Gravity-Driven Membrane filtration

Background Biofouling reduces permeate flux in membrane filtration systems and significant efforts are directed towards preventing biofilm formation on the surface of membrane (backwashing, chemical cleaning, etc.). Practical experience, however, demonstrates that biofilm formation cannot be prevented. Removal of biofilms requires significant amounts of energy and chemicals, which significantly increases costs of operation of membrane systems. Conventional membrane filtration with biofilm control is thus not adapted to the decentralized production of drinking water in developing countries. Gravity-Driven Membrane (GDM) filtration without control of the biofilm formation was recently introduced (Peter-Varbanets et al., 2010) (figure 1). During GDM filtration biofilm formation on the membrane is tolerated and the focus is on maximizing the permeability of the biofilm. Under these conditions a highly permeable biofilm is formed and allows for long-term (several months) operation of the system without maintenance. The operation of the system at constant permeate flux (i.e. constant hydraulic resistance of the biofilm) suggests that the incoming Particulate Organic Matter (POM) is continuously degraded due to endogenous decay processes (e.g. hydrolysis). It is suggested that enhanced hydrolysis of POM is induced by the long solid residence time. What is however not clear is how does hydrolysis impact in turn the quality of the permeate (e.g. release of organic carbon content that increases the risk of pathogen regrowth). The present study thus aims at quantifying hydrolysis activities and at evaluating its influence on the permeate quality over long term (several weeks). An improved understanding of the role of hydrolysis during GDM filtration is an important step towards broadening the application of GDM filtration in both the developed and the developing world. This study would also contribute to better understand the degradation of endogenous process residues in WW treatment plants operated at long SRTs.

Figure 1: Picture of a GDM prototype tested in Kenya for the decentralized production of drinking water (Picture from M. Peter-Varbanets)

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Objectives of the suggested MS topic The objectives of this master thesis will be:

- To evaluate how the long SRT maintained in GDM systems influence the hydrolysis of the organic matter.

- To quantify the hydrolysis rate and the specific activities of different enzymes involved the hydrolysis process (e.g. glucosidase).

- To identify the effect of the organic matter accumulation on the permeate quality.

- To define how to better operate GDM filtration to limit release of organic substrate and the risk pathogen regrowth in the drinking water.

Parallel GDM systems will be operated at different Solid Residence Time (SRT). SRT will be controlled by either controlling the biofilm accumulation on the membrane surface or by removing the settled organic matter in the GDM tank. The performances of the GDM systems will be evaluated in terms of permeate quality and flux. Permeate quality will be monitored in terms of Dissolved Organic Carbon (DOC), Assimilable Organic Carbon (AOC) and organic carbon fractions (biopolymers, building blocks, etc). Hydrolysis process will be evaluated through mass balances and measurement of enzymatic activities (using different fluorescent substrates for enzymes). Specific information This research will be performed in the department of Process Engineering at Eawag. Office space with computer and an existing experimental facility will be provided. Further information about our facilities and approaches are provided at http://www.eawag.ch/membranefilter Advisors Professor Dr. Eberhard Morgenroth Dr. Nicolas Derlon (Eawag) Contact information Name: Nicolas Derlon Email: [email protected] Phone: +41 (0)58 765 5378 References Peter-Varbanets, M., F. Hammes, M. Vital and W. Pronk (2010). Stabilization of flux during dead-end ultra-low pressure ultrafiltration. Water Research. 44(12): 3607-3616.

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Ambient water quality assessment of micropollutants in Switzerland

Background A great number of substances showing a very small effect concentration are irreplaceable in various fields, such as medicine, personal care products, pesticides etc. Some of these so-called micropollutants have been claimed as potentially harmful to not only the aquatic environment but also human health. After the relevance of certain sources have been quantified quantified, the focus can shift towards the receiving water body. Objective and content of the suggested topic The thesis aims to provide a solid basis to indicate whether wet-weather discharges are harmful to the environment. Contrary to waste water treatment plants, where treated waste water is released continuously, urban drainages emit pulses of contaminants. Therefore, a conceptual framework could be used to predict hazards due to wet weather discharges in rivers. Tasks

1. Overview of sources of selected micro pollutants 2. Data assessment (rivers and flow) 3. Adaptation of the concept of “toxic units” to wet weather discharges from

urban areas and implementation into the script language R 4. Combined analysis of the Swiss river network and the sewer

infrastructure by means of Geographic Information Systems (GIS) 5. System analysis and comparison of results with water quality data 6. Development of urban indicators suitable for ambient water quality

criteria Prerequisites Affinity to system analysis and modeling Experience in computer based models (especially conceptual models) good English language skills Experienced with script oriented programming environments (R, Matlab) advisable Advisors Prof. Dr. Max Maurer Dr. Philipp Staufer (Amt für Umwelt, Kanton Solothurn) Contact information Dr.-Ing. Philipp Staufer (Amt für Umwelt Solothurn) Email: [email protected] Phone: +41 32 627 2691

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