The adoption of decision support tools for the definition of cost-effective strategies is seen to gain more importance in the coming years. This development is due for one part to the general degradation of the existing systems and for the other part to changes into the regulations and demands for more transparency in decision-making (Ana and Bauwens, 2007). A key element of decision support systems is the ability to assess and predict the remaining life of the assets (Marlow et al., 2009). For this purpose, deterioration models have been developed to understand and describe the sewer aging based on available CCTV inspections and a list of factors that influence the deterioration. This report first describes the potential sewer deterioration factors and analyzes a panel of literature case studies regarding the relevance of each factor on sewer deterioration. Results are hardly directly comparable, because of the different construction practices, historical backgrounds and environmental conditions of the networks investigated. However, some trends regarding the most significant factors may be identified. In most studies, the construction year and the material seem to be the most relevant factor to explain sewer aging. Pipe size, depth, location and sewer function show generally a medium significance on sewer deterioration. Pipe slope was found to have a low significance for the structural deterioration, but a high relevance on the hydraulic deterioration. The effect of other factors as pipe shape, pipe length, soil type, sewer bedding, presence of trees, installation method, standard of workmanship, joint type, and ground water level have been highlighted but rarely or never investigated. On a second step, this report presents three main approaches for sewer deterioration modeling: deterministic, statistical and artificial intelligence based models. The models can be further categorized into pipe group and pipe level models (Ana and Bauwens, 2010). Pipe group models (e.g. Cohort survival or Markov) can be used to predict the condition of a group of sewers or cohorts and are useful to support strategic asset management, i.e. the definition of long term strategies and budget requirements. These models enable to evaluate the efficiency of several scenarios at the network scale. Pipe level models (e.g. regression, discriminant analysis, neural networks) can be used to simulate the condition of each single pipe. They may be useful to set priorities and justify asset management operations. Pipe level models are tools that can support the utilities in the short and mid-term planning and determine at a finer resolution how, when, and where to rehabilitate sewers. Literature results indicate that cohort survival and Markov models are two useful approaches for modeling the degradation of pipe groups. However, the quality of prediction of these models depends highly on the availability of a large amount of inspection data. Extensive datasets are required to create representative sewer groups (cohorts) with sufficient inspected sewers in each condition state. Regression and Discriminant Analysis were tested on several case studies but showed pretty low prediction performances. Three main reasons could be (i) the non-validity of model assumptions, (ii) the biased distribution of the datasets in terms of number of samples for each condition state and (iii) the lack of data for important deterioration factors. Neural networks have proven to be successful tools for the prediction of the deterioration of individual pipes. However, they require (i) relatively complex and time-consuming training processes and (ii) extensive datasets of CCTV inspection and deterioration factors. Only very few case studies intended to evaluate the quality of prediction of these deterioration models. Furthermore, validation results are often contradictory and hardly comparable since (i) the data available for model calibration differ (percentage of CCTV available, type of deterioration factors available) and (ii) the metrics of the methodologies used to assess the quality of prediction differ. Thus, there is still no clear conclusion about the best modeling approach depending on the modeling purpose (pipe group or pipe level). There is also no clear conclusion regarding the quality of prediction that can be reached since in most case studies only a few percentages of CCTV data were available and many data regarding potential deterioration factors were missing. Further research work is needed in order to (i) identify the most appropriate modeling approach depending on the modeling purpose, (ii) understand the influence of CCTV data availability on the modeling results, (iii) analyze the influence of input data uncertainty (CCTV and deterioration factors) on the modeling processes and (iv) find out the optimum input data requirement (availability of CCTV data and deterioration factors) for model calibration.

Abwassereinigungsprozessen an. In Deutschland fallen jährlich etwa zwei Millionen Tonnen Klärschlammtrockensubstanz aus kommunalen Kläranlagen an. Der Anteil von thermisch entsorgten Klärschlämmen stieg von 31,5 % im Jahr 2004 auf über 55 % im Jahr 2011 an [Umweltbundesamt, DESTATIS 2012]. Eine ökologisch nachhaltige und ökonomische Klarschlämm-Entsorgung wird seit Jahren unter rechtlichen, politischen und technischen Aspekten in Deutschland diskutiert. Die Schlammbehandlung und Entsorgung ist immer noch einer der größten Kostenfaktoren in kommunalen Kläranlagen. Insbesondere die Schlammentwässerung mit Zentrifugen hat einen maßgeblichen Einfluss auf die Betriebskosten. Die Entsorgungsverfahren werden unter Berücksichtigung von Quantität und Qualität des Schlamms und in Hinblick auf die gewünschten Entsorgungsziele kombiniert. Dabei können folgende Verfahrensstufen genutzt werden: Stabilisieren, Eindicken, Konditionieren, Hygienisieren, Entwässern und Trocknen. Die anzuwendenden Verfahren werden entsprechend ausgewählt und in unterschiedlicher Reihenfolge durchgeführt. Die Voraussetzung für die jeweils angestrebte Verwertung oder Entsorgung des Schlammes ist die weitgehende Abtrennung des Wassers von den Schlammfeststoffen. Heutzutage ist eine Kombination mit Eindickung, Konditionierung, maschineller Schlammentwässerung (ggf. Trocknung) besonders von Bedeutung. Die Konditionierung ist dabei eine technisch und wirtschaftlich wichtige Vorstufe zur Schlammentwässerung. Ziel dieser Masterarbeit ist eine Optimierung der Konditionierung und Entwässerung von Klärschlamm unter Einsatz von unterschiedlichen Konditionierungsmitteln mit besonderem Augenmerk auf den Polymerbedarf. Im Rahmen des „Decamax“ Projekts des Kompetenzzentrums Wasser Berlin (KWB) wurde die Schlammentwässerung im Labormaßstab untersucht. Es sollten verschiedene Möglichkeiten der Betriebsoptimierung in der Schlammentwässerung in Theorie und Praxis systematisch verglichen und bewertet werden. Im Fokus der Untersuchungen stand die Zentrifugation mit ihren vorgeschalteten Prozessen wie Schlammvorerwärmung mit Überschusswärme, Flockenbildung vor der Entwässerung und andere Parameter. Im Klärwerk Waßmannsdorf wird seit Anfang der 90-iger Jahre die Phosphateliminierung im Abwasserbereich auf biologische Art vorgenommen. Bei der Schlammbehandlung in Waßmannsdorf wird eine gezielte MAP-Fällung in einem speziellen Reaktionsbehälternach der Faulung und vor der Faulschlammentwässerung betrieben. Durch das Ausgasen von CO2 steigt der pH-Wert deutlich an und dadurch fällt Magnesiumammoniumphosphat (MAP) kristallin aus. Die gezielte Fällung von MAP begünstigt eine bessere Entfernung der freien Orthophosphationen aus dem Schlamm und gleichzeitig führt sie auch zu einer Absenkung des Polymerbedarfes und bessere Entwässerungsgrad. Ziel dieser Masterarbeit ist die Optimierung der Schlammentwässerung in Waßmannsdorf durch Zugabe von chemischen Konditionierungsmitteln wie z. B. Eisen- und Aluminiumsalze sowie Kalk, um eine bessere Entwässerbarkeit zu erreichen. Als Vorbereitungsstufe wurden die Untersuchungen mit den Schlämmen aus der Kläranlage Stahnsdorf durchgeführt. Weiterhin sollte der optimale Polymerbedarf und die Scherstabilität der konditionierten Flocke unter verschiedenen pH-Bedingungen bestimmet werden.

The overall goal of the project Cosma-1: “Geological CO2 storage and other emerging subsurface activities” is the assessment of potential impacts of subsurface activities on shallow aquifers used for drinking water production. The first two deliverables (D 1.1 and D 1.2) dealt with general approaches for risk assessment and a description of potential hazards and hazardous events, which might be a risk for shallow freshwater aquifers, as well as lessons learned from existing geothermal energy production and storage sites in Germany. This Technical Report describes the activities of the second phase of the project COSMA-1 and focuses on the compilation of geological and hydrogeological background data (average values) and the development of a simplified conceptual hydrogeological model for a setting typical for the Northern German Sedimentary Basin. The hydrogeological model of the Cenozoic includes Quaternary and Tertiary aquifers down to the layer beneath the Rupelian clay. On this basis, a numerical model with the program Modflow (PMWIN 5.3) was implemented as no complex geometries had to be considered. The structural geological model of the target formation for underground utilisation, the Detfurth Formation (Middle Bunter), incorporates four different fault systems with nine faults in total enclosing the area of interest. Further, a concept for modeling the interaction between deep, consolidated, saline aquifers with unconsolidated freshwater aquifers in a setting typical for the Northern German Sedimentary Basin was developed. This included the model selection, model parameterization, definition of boundary conditions and implementation in hydrogeological flow model software packages. In the further course of the project, a scenario analysis will be performed by using the numerical hydraulic model of the Middle Bunter and the simplified numerical groundwater model of the Cenozoic. The numerical models will be used to assess the key parameters, having an impact on the upconing of deeper saline groundwater beneath the well fields of water works (in shallow aquifer) due to imposed pressure signals.

Im BMBF-Forschungsverbund „Risikomanagement von neuen Schadstoffen und Krankheitserregern im Wasserkreislauf (RiSKWa)“ wurde die Definition von „Indikatorsubstanzen“ als ein interessantes Querschnittsthema identifiziert. Es wurde dazu eine Arbeitsgruppe gebildet, die sich die Aufgabe stellte, einen Leitfaden zur Zweckbestimmung, Auswahl, Bedeutung und Interpretation von polaren organischen spurenstoffen als chemische Indikatoren zu verfassen. Mit Hilfe der Indikatoren sollten insbesondere anthropogene Veränderungen der Wasserqualität erkennbar sein, sowie natürliche Prozesse und technische Aufbereitungsverfahren überwacht und gesteuert werden können. Diese Indikatoren dienen nicht der Bewertung der Wasserqualität. Mögliche Anwender sind die Bearbeiter in den Verbundvorhaben des RiSKWa-Programms und in weiteren Vorhaben in den Bundesländern, die sich mit Spurenstoffen befassen, Fachbehörden, Forschungseinrichtungen, Wasserlabors der Trinkwasserversorgung und Abwasserreinigung und Ingenieurfirmen, die wassertechnologische Themen der Spurenstoffentfernung bearbeiten. Einen Überblick über mögliche Quellen, Eintragspfade und Barrieren im Wasserbereich zeigt die folgende Abbildung aus dem Bericht eines DECHEMA-Arbeitsausschusses „Pfad- und wirkungsspezifische Indikatorsysteme für Wasser- und Bodensysteme“ (Leitung: W. Dott). Dieser Leitfaden wird dabei sehr wesentliche Teile des dargestellten Systems behandeln.

This report aims at documenting the scientific evidence at 4 managed aquifer recharge (MAR) sites in India after 18 months duration of the EU (European Union) funded project SAPH PANI. The site investigations include compilation of previously existing data, a wide range of field experiments, surface-/groundwater and sediment sampling, data analysis, interpretation and the development of (preliminary) conceptual models. The MAR sites are realised under a wide range of geological and hydrological conditions and the covered aspects can be summarised as:…

Water is one of the sectors where climate change will be most pronounced. While the extents of the impacts are not known yet, it is the right period to prepare the utilities to adapt to the global changes in an urbanising world. Adaptation to climate change, though not always perceived as such, is often already reality in the urban water sector. Several adaptation strategies have been tested to address the key questions: Adapt to what? What to adapt? How to adapt? In this context, within the framework of the EU-project PREPARED, a tentative classification and catalogue of implemented initiatives in the water sector has been compiled. This catalogue is organised into four major categories of initiatives: (1) risk assessment and management, (2) supply-side measures, (3) demand-side measures and (4) global planning tools. The document aims at providing examples on how utilities could go ahead into preparing their water supply and sanitation systems to climate change. Initiatives include various measures ranging from the promotion of active learning to the prevention of sewer flooding and water conservation measures. Within PREPARED, this catalogue is supporting the development of solutions. Being a living document, it is updated regularly along the project when new solutions and initiatives are known. In addition, this work and the subsequent database of adaptation initiatives are accessible to a broader audience thanks to the web-based ‘WaterWiki’ of the International Water Association (IWA).

The study aims at assessing in long-term trials a gravity-driven ultrafiltration pilot plant designed for a capacity of 5 m3/d. The unit was operated in South Africa with Ogunjini surface water and was run with restricted chemical intervention or maintenance (no backflush, no aeration, no crossflow and no chemical). Under South African environmental conditions and with direct filtration of the river water and only one manual drainage of the membrane reactor every weekday, the unit could fulfil the design specification in terms of water production (5 m3/d) as long as the turbidity of the raw water remained in a reasonable level (up to 160 NTU), with a filtration flux typically 4 to 6 L/h.m² (corrected at 20°C). This value was in the same range as the lab results and was consistent with the first phase results (around 5-7 L/h.m² after biosand filtration). However, the flux dropped significantly to a range of 2 to 4 L/h.m² after a rain event resulting in a turbidity peak over several days up to > 600 NTU. This demonstrated that for variable raw water types with expected turbidity peaks above 100 NTU, a pre-treatment would be required for the system (biosand filter or other). The performance of microbiological tests confirmed the integrity of the membrane and the ability of the system to achieve advanced disinfection.