While climate change is an emerging hazard to water supply, literature on the vulnerability of bank filtration (BF), a proven technique of drinking water production in Central Europe and North America, is yet scarce. The Intergovernmental Panel of Climate Change (2007) has projected a global temperature increase between 1.1 and 6.4 °C by 2100. This will affect vital factors for water supply such as precipitation regime, groundwater recharge, run-off, river discharge and raw water quality. Projections on climate change and the implications are difficult because of the uncertainties associated with climate scenarios and modelling. However, in Europe and North America where BF is in operation, the projected increase in seasonal floods and droughts has already been experienced. In addition, site-specific considerations (e.g. land use, demographic trends) are to be taken into account to evaluate the potential impacts on water supply. To fill the current gap in literature, this report provides a first overview on how changing environmental conditions may affect BF operation.

Work package WP 5.2 “Combination of Managed Aquifer Recharge (MAR) and adjusted conventional treatment processes for an Integrated Water Resources Management“ within the European Project TECHNEAU (“Technology enabled universal access to safe water”) investigates bank filtration (BF) + post-treatment as a MAR technique to provide sustainable and safe drinking water supply to developing and newly industrialised countries. One of the tasks of WP 5.2 is to develop a Decision Support System (DSS) as a first qualitative tool to assess the feasibility of bank filtration for drinking water supply in developing countries. The Bank Filtration Simulator (BFS), which is the subject of this report, is a sub-model used within the DSS to compute steady-state solutions for a two dimensional groundwater flow field in the horizontal plane for BF settings. Input parameters are required for aquifer, bank and well characteristics to calculate the BF share analytically. In addition the minimum travel time between bank and well is computed numerically. The sensitivity analysis yielded that the analytical calculated BF share is the most reliable output parameter, since its value is grid-independent. The most sensitive input parameters for the BF share calculation are the hydraulic conductivity of the aquifer and the clogging parameter, which both are the most uncertain ones to estimate. The accuracy of the numerically computed minimum traveltime of the BFS was cross-checked against a MODFLOW model, which produced only a very small discrepancy below 5%. Due to the lacking time-dependency of the BFS model its application is only appropriate on a management horizon for which the system’s boundary conditions (e.g. baseflow, clogging parameter and pumping rates) do not change significantly over time. In a nutshell it is therefore highly recommended to use the BFS only as a qualitative assessment tool in a first planning step to evaluate the feasibility of BF systems. Nevertheless the qualitative outputs give a valuable physically based insight of the system’s behaviour for distinct operational scenarios (e.g. minimal/maximum pumping rates) in order to add transparency and reproducibility to the decision making process.

Riverbank filtration (RBF) denotes the process whereby river water is induced to infiltrate into a groundwater system by well operation adjacent to banks. In Central Europe, RBF has been common practice for 100 years to produce drinking water. Due to the easy implementation and little maintenance necessary, BF has been suggested to be a useful drinking water treatment for developing and newly-industrialised countries. Experience from Europe has demonstrated that RBF is suitable to remove a range of organic and inorganic contaminants while an exhaustion of cleaning capacity has not been observed. RBF systems can mitigate shock loads and are particularly known for the efficient removal of pathogens, suspended solids and algal toxins from surface water, all being water quality parameters of high relevance in developing and newly-industrialised countries. Another benefit of RBF operation is the storage capacity which may help to balance freshwater availability in areas experiencing high variations of precipitation and run-off. This report aims at evaluating the relevance and opportunities of RBF systems to provide safe water to these countries. In order to evaluate the relevance and opportunities of RBF systems to developing and newly-industrialised countries, the report is structured to address key considerations and (i) identify prerequisites for successful RBF operation based on the experience in Central Europe and the United States, (ii) assess the removal potential of RBF for various water contaminants based on available literature, the TECHNEAU investigations in India and NASRI data from Berlin and (iii) evaluate the sustainability and relevance of RBF operation with regard to the particular needs in developing and newly-industrialised countries.

Waterborne diseases are frequent and recurrent episodes in developing countries with deficient sanitary conditions affecting drinking water. Waterborne epidemics might affect thousands of persons, like the Hepatitis-E-epidemics of Kuntra (Naik et al. 1992) and Delhi (Ramalingaswami and Purcell, 1988) with 79,000 and 25,000 ill persons respectively. It is not by chance that both epidemics occurred after drinking water treatment suffered a failure, allowing contaminated drinking water to reach the consumers. In order to ameliorate the consequences of water scarcity and poor sanitary conditions, systems for obtaining drinking water are needed which are efficient, robust, and require only low-cost technology. River Bank Filtration (RBF) is a process during which surface water is induced to infiltrate into the subsurface, either due to a natural hydraulic gradient or the depression cone of an abstraction well. During infiltration and soil passage, the quality of the surface water is substantially improved thanks to a combination of physical, chemical, and biological processes such as filtration, dilution with genuine groundwater, sorption and biodegradation of pollutants Apart from pathogens, organic trace compounds are widespread pollutants in rivers and lakes. The capacity of RBF to effectively or even completely remove both, pathogens and many organic contaminants has been confirmed in numerous investigations (e.g., Matthess et al. 1988). Its low costs in technology and labor makes RBF a very suitable drinking water treatment tool for developing countries. The aim of this study was to ascertain if RBF kept its power to remove pollutants and pathogens even in highly polluted waters as they are encountered in many urban agglomerations in developing countries.

The intention of the work package 5.2 is to analyze the function and relevance of managed aquifer recharge (MAR) techniques with a main focus on Riverbank Filtration (RBF) to enable sustainable water resources management, especially in developing or newly industrialized countries. For this aim three RBF sites in Delhi were equipped with groundwater observation wells and sampled monthly for determination of surface and groundwater quality. This report includes information of more than 150 samples from surface- and groundwater, which were analyzed for a broad series of chemical and physicochemical parameters. For each sample, physicochemical parameters were determined in situ (pH, T, ORP, EC, DO) along with alkalinity, nitrite, ammonia and hydrogensulphide content by the Freie Universität Berlin (FUB) and the Indian Institute of Technology, Delhi (IITD). Additionally, water samples were collected and prepared under appropriate conditions for analysis of inorganic substances (major ions, heavy metals and other inorganic substances) and stable isotopes at FUB laboratories and microbiological parameters and organic contaminants at IIT laboratories. At FUB, in general all parameters were determined monthly except for some heavy metals for which the analysis is very time consuming and costly. For these metals, three sampling campaigns (monsoon, pre- and postmonsoon) were selected for analysis to get an overview of possible contaminations. Investigations on RBF are being performed at three different field sites within the National Capital Territory of Delhi (NCT), two of them on the banks of River Yamuna (Palla and Nizamuddin) and one of them at it’s major tributary in the Delhi stretch, called Najafgarh Drain (Najafgarh). At each of the field sites, at least five piezometers were constructed with varying depths and distances from the surface water. For each field site, groups of piezometers were built, to differentiate surface water and piezometers tapping shallow, medium and deep groundwater. For each parameter distribution and range of the values are shown with boxplots and compared to the German and the Indian drinking water standards. At the Palla field site positive effects during bankfiltration can be observed for several heavy metals like Pb, Al and Cu, while no significant changes or an increase in the concentration can be observed for Fe and Mn, respectively. Other substances like As, NO2- and Ammonia decrease during underground passage while no significant changes or an increase in the concentration can be observed for B and F, respectively. Only Fluoride exceeds the threshold for drinking water standard (Indian standard 1.5 mg/l) and must be considered as critical. At the Nizamuddin field site positive effects during bankfiltration can be observed only for one heavy metal (Al), while no significant changes can be observed for Pb and Cu and an increase in the concentration can be observed for Fe and Mn. Other substances like As, F and Ammonia increase during the underground passage while no significant changes or an decrease in the concentration can be observed for B and NO2-, respectively. At this field site elevated concentrations of several substances like As, Fe, Mn, F and NH4 will make a post-treatment necessary. At the Najafgarh field site the main constraints is the high salinity of the groundwater and the seasonal disavailability of fresh surface water. Due to the high mineralization of the groundwater a possible RBF site must be situated very close to the drain with shallow filter screens in order to obtain a high share of bank filtrate. The design and the potential capabilities of RBF facilities are currently subject to ongoing work and cannot evaluated finally. The sampling campaigns carried out so far are very useful to evaluate i) the seasonal changes in the surface water and ii) the depth dependent changes of the ambient groundwater. It needs to be taken into account that nitrogen species will promote the occurrence of problematic substances like ammonia, nitrite or nitrate due to a load with untreated sewage. Fluoride is expected to be no problematic substance.

Riverbank Filtration (RBF) is a valuable method for the (pre-)treatment of surface water for drinking water production. It has successfully been used in different parts of Europe for more than one century. The main intention of work package 5.2 of the TECHNEAU integrated project is to analyze the function and relevance of Riverbank Filtration (RBF) to enable sustainable water resources management, especially in developing and newly industrialized countries. A review on the attenuation capacity of RBF with a main focus on the significance for developing and newly industrialized countries is given in the D 5.2.3. This report (D 5.2.6) provides an overview on pathogen and organic trace compound content in water samples from the three TECHNEAU riverbank filtration (RBF) sites in Delhi, India. It is a follow up of the D 5.2.1 report that gives an introduction to the studies in Delhi, including regional information to water stressed mega city, environmental conditions at the three field sites and a summary of the hydrogeological investigations. Further information on hydrogeochemistry including inorganic ions (major ions, heavy metals and inorganic trace substabnces) and physicochemical parameters was submitted in D 5.2.2. The data published in this report represents water samples that have been collected during several field campaigns between May 2007 and March 2008 and analysed in different laboratories in India and Europe. Microbiological analysis includes faecal bacteria and indicator bacteria, bacteriophages and enteric viruses. For the analysis of organic contaminants, a non target GC-MS screening was performed as well as a quantitative analysis of pesticides and other trace pollutants.

Membrane processes stand as a promising technology to ensure a safe water supply at the community and the household levels. As the price of membranes has notably decreased over the last years, the market of membrane-based systems for decentralised applications has developed and diversified. In order to have a view of what the current market offers, 204 water companies were contacted and asked to characterise their Point-of-use (POU) or small-scale membrane systems, with a focus set on operation and maintenance, costs and energy requirements. Such study was not performed previously. With a 15% reply rate, the survey enables to identify the different market niches. That includes ceramic POU, organic POU, organic point-of-entries (POE), modular treatment units and emergency systems, whose technical characterization is further detailed in the Annex. Besides, the review of the marketed membrane modules reveals that ultrafiltration is the most available process. The survey also shows that the pre-treatment is a key parameter when considering options for decentralised water supply. As needs for sustainable solutions for small water supply are established, the membrane market is expected to grow and more standardised products to appear. The market evaluation can be summarized in Figure 1. Depending on the product niche, the membrane material and the filtration type, different degrees toward the market maturity are then highlighted. Such systems would be broadly applied in developed countries, but they represent also great potential for transition and developing countries. However, few systems designed for long-term operation with low-energy and low-chemical requirements exist yet. Therefore, the R&D identified within Techneau matches a non-fulfilled yet requirement.

The use of groundwater for public water supply and irrigation has many benefits for water suppliers as well as for consumers. Over the last decades availability and consumption of this valuable resource has increased worldwide along with technical progress, but it has often been ignored that any abstraction of groundwater is an intervention in the balance of the natural water cycle. Managed aquifer recharge (MAR) present the double interest : 1. to be a possible technical answer to over-exploitation of groundwater reservoirs and can contribute to water resource preservation and possibly reuse 2. to provide a natural cleaning step to pre-treat surface water for drinking water supply, and therefore could contribute to reduce the need for highly sophisticated treatment methods which are cost intensive in installation and also in maintenance. In many parts of the world, such as low income countries, MAR offers the possibility to profit from the storage and purification capacity of natural soil/rock and to guarantee a sustainable management of groundwater. River bank filtration is an ancient and widely used method that currently provides water to a large number of population in EU (45% of Hungarian water supply, 16% of German water supply, 5% of The Netherland water supply). River bank filtration relies on natural conditions to operate efficiently and allow to produce a quality of water which, in some cases, doesn't required further treatment before distribution (such as in Berlin). There are now many evidences that global environmental conditions are progressively changing and may impact existing water supply scheme by bank filtration. The extensive study of bank filtration systems in different environmental settings (such as in India with higher temperature, different surface water quality, systems subject to monsoons and flooding ...) will allow apprehending the limitation that current bank filtration systems may face, and highlight the possible need for adaptive strategies. The aim of this report is to document work performed within the first 6 months since the start of WP 5.2 of TECHNEAU integrated project and to give an overview of the results and future planning. This includes detailed regional investigations, field studies and laboratory work performed in collaboration between the KompetenzZentrum Wasser Berlin gGmbH (KWB), the Indian Institute of Technology in Delhi (IIT) and the Freie Universität Berlin (FUB). Preliminary studies at potential sites in different parts of the world were performed prior to the TECHNEAU Project with the aim to investigate their suitability for RBF and thus to allow for deeper investigation within TECHNEAU. These preliminary studies were carried out in the cities Kaliningrad (Russia), Recife (Brazil) and New Dehli (India), and were funded by Veolia Water. In Recife (Brazil), the investigation performed by the FUB showed that both hydrogelogical data and model results indicate that the area is not suitable for the production of drinking water by RBF in sufficient amounts due an unfavorable hydrogeological conditions (too low transmissivity of the target aquifer because of the low content of sand in the samples and the scarce distribution of sandy sediments). At this point further investigations were stopped since no alternative field site area was found. In Kalingrad, water quality data that was gained in the preliminary study from the field site and will be compared with the data gained from investigations in Delhi and Berlin. In Delhi, India, the appropriate conditions, as well as the establishment of a valuable collaboration with the IIT, has lead to the implementation of three different field sites (in three different conditions). The activity performed within the techneau framework and included (i) the integration of existing information and literature on local climate, geology and water supply system, (ii) the detailed investigation about the local hydrogeology and ground and surface water quality and (iii) the development of a GIS (Geo Information System). In agreement with local authorities, three different field sites were selected in the territory of Delhi, representing distinctly different environmental conditions within the district. According to local conditions, a net of 17 groundwater observation points (piezometers) has been designed and installed on each of the field sites. A description of local geology, including stratigraphical charts has been elaborated, based on the evaluation of information obtained during the drilling and from analysis of sediment samples. A strategy for monitoring of water level and water sampling analysis has been developed, and monthly field campaigns have been carried out. Water samples have been analyzed, considering a broad variety of parameters including major chemical contents, trace substances and pathogens. Hydraulic tests have been conducted to obtain aquifer properties in order to estimate travel velocities during underground passage.

The term "Watergy" was coined by the Alliance to Save Energy to describe the strong link between water and energy in municipal water systems. The Watergy approach helps cities realize significant energy, water and monetary savings through technical and managerial improvements in water supply and wastewater treatment systems, creating efficiencies that provide consumers with quality service with a minimum of water and energy. Efficiency in the water sector involves both the end use of water - such as efficient toilets, low-flow showerheads and reducing peak demand - as well as efficiencies in the supply of water. This paper focuses on the water supply system itself since in many cities most of the inefficiencies occur before the water even reaches the end user. Watergy principles have been applied in numerous cities around the world, demonstrating that water efficiency measures repay themselves quickly and yield many rewards: improvements in water service, immediate increased water delivery, reduced water and energy consumption, and more revenue for system upgrades and new customer connections. Opportunities abound throughout all stages of a water supply system. The most promising areas for intervention within water supply systems are: (i) improving the pumping system, (i) managing leaks, (iii) automating system operations, and (iv) regular monitoring (preferably with rigorous metering of end use). These improvements often pay for themselves in months, most do so within a year, and almost all recover their costs within three years. The pumping system is all important, since every liter of water that passes through the system represents a significant energy cost, a cost that is magnified by every liter lost to leaks. Pumping improvements range from lower cost measures like soft starters for motors, trimming impellers (when pumps are over-sized) and re-winding motors, to higher cost measures like replacing inefficient pumps with efficient ones and installing variable speed drives. System automation saves water, energy and operation costs, improves service, and lengthens equipment life. Automation handles operational functions in real time in response to changing situations. Examples are optimizing pressure in the network, triggering alarms in case of emergency, and turning off pumps. Regular monitoring of the system components, operations, and performance is essential targets. in order to track performance and evaluate it against a set of benchmarks and Incorporated as part of the larger O&M protocol, monitoring is a no- or low-cost efficiency enhancement within reach of all utility budgets. Effective management of leaks can save enormous quantities of water and energy. Leakage rates can be lowered dramatically with automated controls that reduce pressure in the network, especially at night. Pressure management is generally more cost-effective than expensive repairs to numerous leaks in buried pipes. This paper provides a comprehensive overview—suitable to all technical levels—to introduce the reader to the approaches and benefits of Watergy. It is intended for a wide audience ranging from municipal and water utility decision makers, to funding organizations, to technical utility staff who want a solid understanding of what a water efficiency program entails without a high level of technical detail.

Access to microbiologically and chemically safe water is limited not only in developing countries, but also in transition countries and even in remote areas of developed countries. For these cases, decentralized water supply concepts such as point-of-use (POU), point-of-entry (POE) or small-scale system (SSS) technologies can be promising alternatives to centralized treatment concepts. Membrane-based treatment systems have gained importance for drinking water treatment in the developed countries. In principle, application of membrane technology is attractive also for the transition and developing countries, because it provides absolute barriers for control of hygienic hazards (Ultrafiltration (UF)) and because the modular construction enables implementation on each possible scale size. However membrane technology is still not affordable for the poorest part of the world population. The sustainable application of POU membrane system presumes that system should be operated without or with limited addition of chemicals, with limited possibility of regular backflushing and with low pressure, presumably hydrostatic. On the other hand, while the water needs for drinking and cooking for a family of four people constitute approx. 20 l/day, operation of POU UF system under low flux conditions is possible. One of the most important limitations for application of ultrafiltration in simple household devices, is membrane fouling. In order to overcome the reasons of the limited application of UF in POU systems, the better understanding of the UF process in these specific conditions and specially membrane fouling is needed. Recent studies have shown that dissolved or colloidal polysaccharides and proteins and their interactions with the membrane and between macromolecules might have more severe impact. During long term dead-end filtration, accumulation of the macromolecules on the membrane surface and increase of their concentration is severe. The interactions between those macromolecules in the conditions of high concentrations in the boundary layer affect the structure of the layer and its permeability. However, in most of the studies, only the foulant-membrane interactions are considered like relevant for reversibility of fouling. The foulant-foulant interactions in the boundary layer have been studied only superficially. Therefore, we systematically investigated the impact of polysaccharide and solution properties on UF membrane fouling in conditions of low flux and limited backflushing, under constant TMP conditions (hydrostatic pressure of 120 mbar - 150 mbar. Our experimental results lead us to the following conclusions: Regarding the initial stage of flux decline (0-80 ml permeate/cm2) the polysaccharide structure, and particularly availability of carboxyl groups, has a major impact on the membrane fouling, while the molecular weights of polysaccharides does not play a significant role (in the studied range of Mw 5-250 kDa). Such solution conditions as presence of metal ions and ionic strength are also detrimental for the fouling, while both metal ions and ionic strength have impact on the gel structure and properties, generally stabilizing it, and increasing the possibility of water trapping by hydrogen bonding, which leads to the higher permeability. However, independently of the initial solution conditions, after approx. 80 ml has been filtered through 1 cm2 of the membrane, flux becomes stable on the level of approx. 10 L/(hm2) over the whole period of operation (several weeks in some cases). We suppose that the gel layer formed by polysaccharides play a role of a “second” membrane on the surface of the PES UF membrane, keeping remaining permeability on the certain level, determined by the water retention properties of the gel structure. Regarding practical application, the obtained results open a new direction for the ultrafiltration in specific conditions of household systems. The long term ultrafiltration should be studied on natural waters to prove the flux stabilization phenomenon. This phenomenon may give a possibility to produce up to 10 L/h of water from 1 m2 of the membrane applying only 120 mbar of hydrostatic pressure (1.2 m water level difference) without backflushing or crossflow, which may simplify the design and maintenance of the system and significantly reduce its costs. Next activities in Techneau project will include the further evaluation of the long term ultrafiltration on natural waters; characterization of the impact of biofouling on the flux decline; and evaluation of the operational parameters of the Point-of-use system, based on the proposed above concept to treat at least 20 L/day.