The use of bank filtration for drinking water treatment in Europe dates back to the days of beginning industrialization in the 19th century. With regard to improved source water quality in Europe, the millennium development goals and global climate change, aquifer recharge (AR) and bank filtration (BF) need to be reassessed in terms of sustainability and their role within an integrated water resource management. Based on the IC-NASRI study comprising 194 drinking water facilities worldwide integrating aquifer recharge techniques in their treatment system, an average AR/BF site would be located in Central Europe alongside a river and is characterized by: a sandy gravel aquifer with a hydraulic conductivity of 2x10-3 m/s, a maximum aquifer thickness of 30 m, 175 m travel distance from bank to well, a travel time of 70 days and by vertical well operation with a daily capacity of 55.000 m³. A literature survey conducted within the TECHNEAU project demonstrated that for substances highly relevant to newly-industrialized or developing countries (e.g. pathogens) the removal efficiency is good. Hydro-chemical analyses from three study sites in Delhi support these results. However, it was also shown that poor surface water quality, saline groundwater or subsurface conditions leading to mobilization of trace metals like iron, manganese or arsenic may limit the applicability of AR / BF without further post-treatment. Climate change might affect the performance of AR / BF worldwide, impairing source water quality and influencing removal efficiency. However, other factors like changes in demography or land-use can impact the systems by far more severely.

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.

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.