The present study provides an overview of geogenic contamination, its occurrence, impacts and possible treatment options for drinking water production. Natural background and anthropogenic contamination can be differentiated using an algorithm based on the frequency distribution of measured substance concentrations. Case studies for geogenic contaminants such as ammonium, fl uoride, chloride, sulfate and uranium are discussed based on the origin, occurrence, controlling factors and treatment options. It is suggested that, in case of occurrence of geogenic contaminants, water must be treated or alternative sources need to be found, e.g., managed aquifer recharge, prior to the distribution as drinking water.

In order to efficiently tackle odour problems from sewers which are connected with resident’s complaints and health risks, reliable online odour monitoring is necessary. Multi-gas sensor systems (electronic noses), which display a broad range of odorants, may substitute common online odour monitoring devices in the future. Four electronic noses with different configurations were tested over a period of 8 months at a sewer research plant of Berliner Wasserbetriebe. The objective was to analyse the applicability of four electronic noses for sewer odour management. 11 evaluation criteria were defined to evaluate the E-noses measurement behaviour, stability and their general practicability and handling. Generally it can be mentioned that the results are promising and the E-noses show good potentials. The E-noses which showed good results in predicting the odour concentration at the site have lack of some practical features. Whereas the systems which provide more possibilities (e.g. remote control, direct odour display) and have more complex gas preparation or measurements modes (like thermal desorption) showed lower capabilities to measure the actual odour at the site.

Combined sewer overflows (CSO) after heavy rainfall can cause acute depletions of dissolved oxygen (DO) in the Berlin River Spree. A planning instrument for CSO impact assessment has been developed in the framework of the research project MIA-CSO at the Kompetenzzentrum Wasser Berlin. This instrument couples the sewer model InfoWorks CS, the water quality model Hydrax/QSim and an impact assessment tool. Within this thesis it is tested for various CSO management strategies and climate change scenarios. The coupled sewer-river-model InfoWorks CS-Hydrax/QSim was validated for the years 2010 and 2011. Simulation results for the critical parameters discharge and DO concentrations in the Berlin River Spree agree well with measurements. Although not all observed DO deficits can be simulated accurately, the very good representation of processes related to the oxygen budget allows assessing relative changes in boundary conditions, e.g. from different CSO control strategies. The conducted scenario analysis indicates that the coupled sewer-river-model reacts sensitively to changes in boundary conditions (temperature, rainfall, storage volume and other CSO control strategies, etc.). Based on the simulation year 2007 - representing an extreme year with regards to CSO volume and critical conditions in the river - sewer rehabilitation measures planned to be implemented until 2020 are predicted to reduce total CSO volumes by 17% and discharged pollutant loads by 21-31%. The frequency of critical DO conditions for the most sensitive local fish species (<2 mg/L) will decrease by one third. For a further improvement of water quality after the year 2020, the reduction of impervious surfaces emerges as a very effective management strategy. A reduction of the impervious connected area by 20% results in a decrease in the frequency of critical DO conditions by another third. The studied increase in surface air and water temperature as part of the climate change scenarios leads to a significant aggravation of DO stress due to background pollution in the Berlin River Spree, while acute DO depletions after CSO are barely affected. However, changes in rain intensity have a considerable effect on CSO volumes, pollutant loads and the frequency of critical DO concentrations. The extended sensitivity analysis shows that a general reduction of discharged pollutant loads by 60% based on the sewer status 2020 can prevent critical DO conditions in the Berlin River Spree, even for the exceptionally rain intense year 2007. Further, it has been shown that the entry and biodegradation of organic carbon compounds is the most important process for acute DO depletions after CSO. However, mixing of oxygen free spill water with the Berlin River Spree provokes an additional impairment of DO conditions. In the framework of this thesis, CSO impacts under different management strategies or climate change conditions are only assessed for a part of the Berlin combined sewer system and for one exemplary year. Before applying the presented instrument for planning specific measures it is proposed to expand the model area and simulated time period.

Within the context of continuously increasing CO2 concentrations in the atmosphere, as well as diminishing reserves of fossil fuels, finding new ways for autarkic and “climate friendly” energy production becomes more and more important. The development of emerging subsurfaces activities like Carbone Capture and Storage, and Hydraulic Fracturation might offer new options to tackle all three of the mentioned challenges. But, carbon capture and storage (CCS) and unconventional gas exploration (“hydro-fracking”) have in common that they impact parts of the subsurface and may thus potentially have an effect on fresh water aquifers. The combination of all the most recent studies about GCS and Hydro-fracking, allows the identification of a broad panel of key parameters that can assess and indicate a groundwater contamination resulting from emerging subsurface activities. Strong emphasis needs to be put on the fact that numerous new monitoring, verification and accounting tools are being developed worldwide threw researches programs. However, actually, it seems that the most efficient monitoring and early warning network should be based on the combined used of the most suitable (site-specific) geophysics and geochemicals tools.

The goal of this study is to analyze whether the integration of a Hydrothermal Carbonization (HTC) process into sewage sludge disposal routes improves the holistic energy balance compared to state of the art technologies. Furthermore the decisive parameters for the improvement are identi ed. For this a static model is set up within the energy and material flow calculation software Umberto. Within the selected treatment scenarios without and with anaerobic digestion the Cumulative Energy Demand (CED) and Global Warming Potential (GWP) are determined per functional unit disposal of one kg TSsludge. The model is fed with full-scale data from state of the art sludge treatment and data of a pilot HTC plant. It comprises all relevant processes including their chemicals and energy demands as well as transportation of materials. Expenditures for infrastructure are excluded. The reference input flow is based on the annual sludge amount of a waste water treatment plant for 500,000 people equivalents. The final disposal options of the sludge or hydrochar are either co-incineration within a lignite power plant or mono-incineration. Some co-products such as electricity, biomass fuel (dried sludge, hydrochar) and nitrogen fertilizer are created during sludge treatment and accounted for as substitutes for production of equivalent resources. HTC distinguishes from the conventional sludge treatment by improved mechanical dewaterability of the products. It reaches dry matter contents of ~ 65%. Trade-offs are the significant process heat demand of 88kWh/m3 sludge at high temperatures > 220 °C and a decreased mass yield of 72 % for the undigested and 75 % for the digested sludge. The dry matter loss results in process liquor with multiple load compared to raw sludge liquor (80 x org. C, 60 x Ntot, 25 x Ptot). The CED and GWP results generally show good correlation. For the CED of raw sludges the net values range from savings of -11.7 to expenditures of +1.8MJ/kg TS. The GWP ranges from -1.07 to +0.43 kg CO2-eq/kg TS. The net values for the HTC scenarios exceed the reference scenarios for undigested sludge when the dry matter content after sludge dewatering is < 27% or if it is ~ 27% and the process heat demand of the HTC can be reduced by half e.g. via insulation. However, the best scenario for undigested sludge includes HTC with a small scale digester only for the liquor. The loads are largely reduced, saving energy for the return ow treatment and producing biogas for use in a CHP plant. The heat can be fed to the HTC reactor while grid electricity is substituted. In disposal routes including sludge digestion the CED ranges from -11 to -1.1MJ/kg TS and the GWP ranges from -0.73 to +0.22 kg CO2-eq/kg TS. The scenarios with HTC exceed the reference scenarios irregardless of the TS after dewatering. The HTC liquor is returned to the digester, reducing the load and yielding extra biogas as mentioned above. Also, with sludge digestion the HTC process benefits from the larger amount of CHP heat. It is sufficient to cover the heat demand within the analyzed scenarios. The reference sludge treatment is based on representative full-scale data, but the pilot plant data of HTC showed inconsistencies. The data has to be validated in full scale. Furthermore, important aspects such as refractory COD within the hydrochar liquor, pollutants such as heavy metals, legal aspects of the hydrochar incineration, nutrient recovery and economic aspects have to be addressed in future studies.

Objective of this synthesis report is to summarize the main achievements of the WELLMA-2 project. Based on the preparatory phase WELLMA-1 (2007-2009), the main project phase WELLMA-2 (2009-2012) included extensive laboratory, pilot-scale and field site investigations aiming at optimizing the operation and maintenance of drinking water production wells with respect to costs, energy efficiency and sustainability. The main reason for inefficient well performance is so-called well ageing. Deposit formation due to multiply correlated biological, chemical and/ or physical clogging processes in and around the well cause a decrease in performance. Thus, the interdisciplinary WELLMA-project team aimed at improving the efficiency of drinking water production wells by providing a scientific basis to support operators in their efforts to reduce well ageing. This included the development of guidance and recommendations for an adapted and well-planned operation scheme and maintenance strategy to sustain or reinstall the well performance. Well ageing processes were intensively studied at a multitude of vertical drinking water production wells located in Berlin, Germany and near Bordeaux, France. Thereby, classical monitoring and diagnosis methods, such as pumping tests and TV inspections, but also newly developed own experimental setups, such as the in-situ measurement of oxygen, depth-oriented water sampling or the exposure of object slides and bio-reactors for biofilm growth were applied. This synthesis report follows the project outline featuring four work packages dealing with (i) the identification of ageing types and the site-specific ageing potential from optimal data processing of site and well characteristics to provide decision support for the diagnosis and subsequent optimisation of well operation, monitoring and maintenance, (ii) field methods and experimental setups applied within the WELLMA-project to investigate mixing processes, oxygen uptake and biofilm formation, (iii) the impacts of intermittent operation on the uptake potential and distribution patterns of oxygen, and (iv) the efficiency of hydrogen peroxide treatments for preventive well maintenance against biochemically induced iron ochre formation and the oxygen uptake potential correlated to the decomposition of H2O2. Intermediate data were presented at various occasions at scientific and practiceoriented conferences, e.g. the Association for General and Applied Microbiology (VAAM), the International Water Association (IWA) Groundwater conference, International Association of Hydrogeologists (IAH), Berlin-Brandenburger Brunnentage, Wasser Berlin etc. and in related papers. A publication list is given at the end of this synthesis report.

Recent infrastructure studies underline the general deterioration of sewer system and the risk reversing public health, environment and increasing costs (ASCE, 2009). Since the origin of sewer systems in the 19th century, sewers have been installed at different periods using available standards and technologies. Sewer assets have limited service life and it is crucial to assess their condition throughout their life cycles to avoid potential catastrophic failure and expensive emergency rehabilitation due to their deterioration (Hao et al., 2011). This report first presents the wide panel of inspection technologies available to obtain information about sewer defects and condition. Visual inspection (e.g. Closed-circuit television CCTV, zoom camera) appears to be the industry standard for sewer inspection. It provides visual data (images and/or videos) of the internal surface of the pipe. Defects are usually coded manually by the inspection staff according to standard coding methods. In Europe, the current codification system is the normative EN 13508-2 for visual inspection (EN 13508-2, 2011) used by the CEN-Members (European Committee for Standardization). In addition, physical techniques are available that can give further information and details about pipe defects. These techniques do not replace the CCTV inspection but can give deeper insights on the type and severity of defects. Sonar and Lasers enables to analyze pipe geometry and can identify defects such as deflections, cracks, sediments or corrosion. Ultrasonic testing and magnetic flux leakage (MFL) are applied directly on the pipe wall. They enable to measure wall thickness and detect pipe defects such as corrosion, deflections and cracks. Ground Penetrating Radar (GPR) and Infrared Thermography are used from above ground and are useful to locate pipes and identify bedding conditions, voids and leaks. Finally, network wide inspection technologies like smoke testing or Distributed Temperature Sensing (DTS) can locate cross-connections and/or sewer infiltration. The purpose, inspection procedure and limitations of these methodologies are briefly presented. On a second step, this report presents the available classification methodologies developed to interpret automatically visual CCTV inspection reports and evaluate sewer condition. These methodologies enable to transfer the extensive amount of visual inspection data from CCTV inspection into a more easily manageable number, useful to support asset management practices. Most approaches have a similar goal: they aim to rank rehabilitation priorities and support municipalities in the definition of rehabilitation programs. They do not pretend to replace the knowledge and analysis skills of a local expert but can help him to identify rehabilitation priorities. All methodologies provide an overall condition score for each sewer segment or sub-scores for different requirements (e.g. structural and operational condition) or dysfunctions. From the review of available methodologies, two main approaches can be distinguished: priority based and substance based methodologies. For priority based methodologies, the calculation of sewer condition grades is based on the most severe defects, the density of defects and/or the defects length. Condition grades express the priority of rehabilitation, i.e. the emergency of action regarding the probability of failure or collapse. For substance based methodologies, the final score is calculated based on the length of sewer that will be affected by rehabilitation actions. Substance based methodologies do not aim to assess the condition of sewers but rather to rank sewer pipes considering the amount and type of rehabilitation needs: replacement, renovation and repair. Each methodology aggregates and combines sewer defects in a very different way making very hazardous the benchmarking of final scores from different methods. Therefore, municipalities using different evaluation system are not able to benchmark the condition of theirs networks. Finally, the accuracy of the classification results remains a key issue, crucial for the further use of inspection data to support asset management strategies.