Municipal solid waste (MSW) in landfill bioreactors is subjected to mechanical, biological, and hydrological processes. To understand these processes, four large-scale bioreactor pilots were specifically designed to simulate the behavior of waste in the core of a landfill. Here, the results of two long-term tests that were performed in two compression cells are presented. Mechanical, biochemical, and hydrological parameters were analyzed throughout the experiments. The promising results of this research improve the understanding of biodegradation and its correlation with the hydromechanical behavior of municipal solid waste. In particular, the sensitivity of the biodegradation to leachate injection and the correlation between the biogas flow and vertical settlement were confirmed for wastes with high initial moisture content. The results showed that it is important to consider the potential of different monitoring techniques and the representative volume for the experimental approach. Furthermore, the operational results led to interesting conclusions, especially regarding the addition of moisture to waste, which is a key element for bioreactor landfill operation.

Wastewater reuse is increasingly considered as possible alternative water source for diverse non-potable uses. Among the major questions, defining which water quality for which reuse is required is crucial. If the demand for reclaimed water is seasonal, the question of reclaimed water storage is also essential. Aquifer recharge for further nonpotable reuse can be a solution to address many final reuse applications, including indirect agricultural or landscape irrigation, saltwater intrusion barriers, subsidence mitigation/aquifer replenishment or other non-potable reuses. Most of the aquifer recharge applications of wastewater reuse so far rely on high-pressure membrane systems or even double-membrane combined with advanced oxidation processes. However, when non-potable reuse is targeted, or the replenishment of a threatened aquifer is planned, recharge with high-quality non-potable water could be envisaged as acknowledged by the legislation of several countries. In this report, the performance of hybrid disinfection/filtration and recharge schemes is assessed in comparison to a high-pressure membrane system working under similar conditions. Among the portfolio of available disinfection and filtration technologies, five treatment trains were chosen – combinations of ozone or UV treatment with sand filters or UF membrane and final infiltration or injection – and compared to a double-membrane system (UF+NF). A synthetic secondary effluent (SE) was considered for this conceptual study on the basis of a worldwide survey of typical SE water qualities. The major legislations from the WHO, the USEPA and Australian guidelines were considered to define the water quality to be reached by these hybrid treatment schemes. The low targeted value in suspended solids (10 mg/L) and microbiological contaminants (1 fecal coliform / 100 mL) requires extensive disinfection and filtration processes. The proposed schemes were selected on the base of a large review of typical pollutant removal efficiencies found in the literature. To perform a comparative Life-Cycle Assessment of the different treatment trains, similar assumptions were made in all cases for a hypothetical case study of a 50,000-PE reuse plant downstream of a secondary sewage treatment plant. All five proposed hybrid treatment trains are capable of supplying very high non-potable water quality, and the combination of disinfection, filtration and aquifer passage proved to be an efficient combination for removing suspended solids, residual BOD and microbiological contaminants. The environmental performance of the treatment trains was compared in terms of carbon footprint, but also energy demand, human toxicity, acidification impact and land footprint. Both the energy demand and carbon footprint of hybrid schemes was found to be considerably lower than for a double-membrane system, besides offering an additional storage solution in the aquifer. Thus, there is a significant margin for lowering the environmental impact, energy demand and operational costs if non-potable water quality is sufficient for the reuse goal. However, the legal context and social acceptability may represent barriers for this intended recharge of nonpotable water to the aquifer. This conceptual study has shown the potential of hybrid solutions to provide high-quality non potable water for aquifer recharge and further reuse. A large portfolio of solutions was proposed to reach the intended non-potable uses. To assist the selection of adequate treatment trains, the strengths and weaknesses of the solutions can be summarized in a decision tree taking into account the reuse goal, aquifer type and space availability, and selecting the least energy-intensive solution for a given legal and sociocultural context.

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).

Water is one of the sectors where climate change will be most pronounced, but at the same time it is one of the sectors where numerous adaptation possibilities exist. 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 urbanizing world. Adaptation to climate change, though not always perceived as such, is already reality in the urban water sector. In this context, within the framework of the international research project PREPARED funded by the European Commission and, among others, Veolia Water and local utilities, a toolbox consisting in a catalogue and a dynamic matrix of initiatives in the water sector is being compiled by the Berlin Centre of Competence for Water, KWB.

This report concludes the first phase of the project “OptiWells”, which focuses on the optimization of drinking water well field operation with respect to energy efficiency. The purpose of this document is to provide sound answers to questions that utilities and well field operators are facing. Thus, it is built as a thematically organized sequence of main questions and answers rather than an extensive manuscript-like report. In total, 13 questions are addressed in detail, while 3 main “unanswered” questions and issues are detailed at the end of this report. The focus of this report is identical to the project’s focus: it addresses energy efficiency issues within the well field system. Thus, the main area of focus of the project lies in the interactions between the groundwater, the well, the pump and raw water pipe system. Drinking water treatment, as well as water distribution is not included in this study. This document, in combination with the other project deliverables, shall provide an overview of the potential optimizations for drinking water well fields. It shall yield both answers about saving potentials in general, and give some concrete examples from a French well field. By doing so, it shall assist the identification of solutions for an energyefficient groundwater abstraction, and provide a basis for a sound, practical methodology for well field energy audits and assessments.

The optimisation of drinking water well field operation may significantly reduce the energy demand and associated costs, but is seldom applied in a systematic methodological approach. In this study, a well field was analysed using a coupled model that takes into account aquifer, wells, pumps and raw water pipes. This coupled approach enabled to identify and quantify the key energy demand drivers. The geometrical elevation was the most important driver, while pipe network losses were in the same order of magnitude as aquifer- and well losses. Using the modelling tool, the most energyefficient well field operation scheme could be derived and energy savings of up to 17% may be achieved by optimising well field operation only whereas further 5% may be saved by investing in new pump equipment. These findings show the potentials for significant energy savings in the field of drinking water abstraction.

In the 2nd phase of the project (OXIRED 2), trials at lab and technical scale were conducted to validate the results for trace organic and DOC removal from OXIRED 1 and to gain a more reliable knowledge about oxidation by-product formation for surface water from Berlin. To assess the stability of the process, a pilot unit was operated at Lake Tegel. Moreover the effect of oxidation + MAR on toxicological parameters was investigated (s. D 1.1). To prepare a field study three sites in Germany were evaluated regarding their suitability including parameters such as aquifer depth and composition, source water quality and possibility of authorization (s. D 2.1). The results were that none of the sites (Hobrechtsfelde, Braunschweig WWTP or artificial recharge site in Görlitz) was identified as suitable. The current state-of-the-art for influencing the redox zonation in the subsurface was reviewed (D 3.1) and the options to assess the quantity, composition and activity of the microbial population in the soil samples were summarized (D 2.2). To investigate the dynamic of redox processes, short term column tests were conducted (D 3.2). On the basis of these results reactive flow and transport modelling was carried out (D 3.2 and 3.3). The aim of this report is to give a summary of the main results from OXIRED 2 and to identify promising opportunities for further experiments and transfer to field scale.

There is a significant potential for optimizing pump systems currently in use in groundwater wells. This potential lies in: (i) the improvement in pump technology, which can yield up to ~5% more efficiency, (ii) the improvement in motor technology, which can yield up to ~3% more efficiency, with further improvements if innovations from aboveground motors are adapted, (iii) the improvement in performance adaptability, which can be very efficient in some cases (~10-50%), but also counterproductive if not adapted to current situation (0% or even efficiency loss), and sometimes not very flexible (impeller trimming); (iv) the improvement of the system maintenance and management which may yield up to ~20% more efficiency, and which, in general, has a shorter payback time than performance adaptability options.The improvement of equipments may induce only moderate additional costs if it is done at the time of scheduled new investments, after amortization of the equipment formerly in use. Unfortunately, these expected savings are influenced by uncertainties, which can be of the same order of magnitude as the savings themselves. For instance, the determination of the optimal operation point of a pump bears uncertainties between 1% and 4% and grows with pump rotation speed (Gülich 2010). Other considerable saving potentials lie within cleaning, maintenance and smart wellfield operation with short to moderate payback times (Table 6). These potentials are however very site-specific, and difficult to estimate on a general basis. Best practices for a “smart” pumping shall include choosing equipment that fits the actual requirements of the system, operating the pumps nearest of their Best Efficiency Point, and operating the motors in an energy-efficient load range. The most obvious energy savings are those associated with improvements in the efficiency of the motor and of the pump (Shiels 1998). Such gains are often worth the added capital expenditure – although often having moderate to long payback times. However, as underlined by (Kaya, Yagmur et al. 2008), that pumps have high efficiency alone is not enough for a pump system to work in maximum efficiency. An improvement of pump technology will yield, even optimistically seen, an efficiency improvement of up to 10%, which is the potential “theoretical limit” (EC 2003). For further improvements, it is necessary to consider solutions that go beyond the pump system, since maximizing efficiency depends not only on a good pump design, but also on a good system design. Even the most efficient pump in a system that has been wrongly designed is going to be inefficient. Moreover, an efficient pump in an inefficient well is pointless. Hence, a global approach of the groundwater abstraction system is required. The optimization potentials highly depend on the site characteristics themselves, on the local demand (what distribution of the demand? what load profile?), and on the operation and maintenance history (e.g., what is the cleaning frequency of the pipes, if any?). Finally, one should not forget the primary objective of water abstraction, which is satisfying a given water demand, thus, the safety of drinking water production prevails over energy efficiency.