Riverbank Filtration Hydrology

Riverbank Filtration (RBF) has gained popularity in the past decade as an excellent source of high quality water for public water supply. This text compliments the existing literature on RBF water quality, and provides much-need guidance in the design and operation of RBF facilities. RBF has proven effective in many hydrogeological settings worldwide, and can be an excellent solution to water supply problems in both developed and developing countries. Topics covered include surface stream hydrology, particle clogging, and biological/geochemical processes. Data and case histories are provided from dozens of installations, providing much-needed practical information regarding RBF design, operation, and performance. This book provides the necessary tools to evaluate potential RBF sites, and is a must-have if you are considering RBF as a source of water supply.

Chittaranjan Ray, Ph. D. , P. E. University of Hawaii at Mãnoa Honolulu, Hawaii, United States Jürgen Schubert, M. Sc. Stadtwerke Düsseldorf AG Düsseldorf, Germany Ronald B. Linsky National Water Research Institute Fountain Valley, California, United States Gina Melin National Water Research Institute Fountain Valley, California, United States 1. What is Riverbank Filtration? The purpose ofthis book is to show that riverbank filtration (RBF) isa low-cost and efficient alternative water treatment for drinking-water applications. There are two immediate benefits to the increased use of RBF: Minimized need for adding chemicals like disinfectants and coagulants to surface water to control pathogens. Decreased costs to the community without increased risk to human health. Butwhat,exactly, isRBF? In humid regions, river water naturally percolates through the ground into aquifers (which are layers of sand and gravel that contain water underground) during high-flow conditions. In arid regions, most rivers lose flow, and the percolating water passes through soil and aquifer material until it reaches the water table. During these percolation processes, potential contaminants present in river water are filtered and attenuated. If there are no other contaminants present in the aquifer or ifthe respective contaminants are present at lower concentrations, the quality of water in the aquifer can be ofhigher quality than that found in theriver. In RBF, production wells — which are placed near the banks ofrivers —pump large quantities ofwater.

This report provides addresses the basic hydrology of RBF systems, focusing on the interaction of the river, the riverbed, the aquifer, and the well, along with the associated parameters that influence how much water will flow from a given system at a given site. The primary parameter evaluated was specific capacity (pump discharge per unit drawdown). Site and water quality characteristics thought to impact specific capacity were also evaluated, including stream velocity and slope, riverbed shear stress, riverbed media composition, aquifer and riverbed hydraulic conductivity, and river quality and temperature.

Riverbank filtration is widely used in Europe and to some extent in the United States for the public water supply. It is a cost-effective and realisable treatment technology in which horizontal and vertical wells pump a mixture of ground water and induced surface water from a river. This book describes the biogeochemical issues involved in contaminant removal from surface water and the mechanisms of pathogen removal. Specifically, the following three points are considered: *The role of hydrogeological and well construction factors in the development of redox zones at bank filtration sites and the resulting impacts on contaminant removal. *The mechanisms of pathogen removal, including the processes, colloid filtration, die-away, decay, and predation. *The status of riverbank filtration processes in NATO partner countries.

The objective of this research was to investigate the clogging process in riverbank filtration (RBF) systems and identify factors significant to yield. Specific objectives included the following: Evaluate commonly available stream and aquifer characteristics from RBF systems with regards to system yield Collect data from the RBF system in Louisville and apply the information to clogging theory Provide recommendations regarding the design of future RBF systems with regards to riverbed clogging Data from the participating sites were compiled to allow easy comparison to future RBF sites. High-capacity RBF systems have been constructed in a wide range of hydrogeologic settings, and data from these sites provide insight to capacity-limiting factors in RBF systems. Field data for temperature, head, and riverbed flux rates into the riverbed were collected at Louisville, allowing estimates of riverbed hydraulic conductivity to be calculated as a function of distance from the well. These data indicated variations in riverbed hydraulic conductivity resulting from riverbed clogging and the development of unsaturated conditions. The impact of temperature on specific capacity was evaluated at four sites where adequate operating data were available. Wide variations in water viscosity associated with temperature resulted in the doubling of specific capacity from winter to summer, indicating that the rated capacity of RBF systems should be considered as a range between coldest and warmest water conditions. Information from this project was summarized into a set of recommendations for utilities considering the design of an RBF system for future water supply.

Riverbank filtration is a low cost, yet efficient water treatment technology. It has most potential to provide safe drinking water to large cities located along rivers or lakes. In particular, it is ideal for large population centres in developing countries, where the cost of building extensive treatment facilities is prohibitive. Water filtration can be successfully implemented using naturally occurring sand and gravel along the river/lake banks. The cost of water produced by this means is much lower than that of water treated in conventional treatment plants. Authored by a multi-disciplinary team of experts, this volume addresses the scientific basis of the filtration process, and also numerous topics of importance for the planning, technical realization, and security of such plants. Their application for the removal of relevant chemical pollutants and a variety of pathogens is analysed in detail.

Sustainable technologies for water supply are urgently needed if water has to be supplied to billions of less fortunate people with inadequate access to water. These technologies must be simple, less expensive, less energy intensive, and easy to maintain for their adaptation among the poor masses. Four appropriate technologies are discussed here: solar pasteurization, membrane desalination, natural filtration (riverbank filtration), and solar distillation. Solar pasteurization can be a useful means of producing water at remote, but sunny locations where fuel may not be easily available for boiling water. Membrane desalination will remain as a viable means of drinking water production for individual households to large communities. Various membrane filtration techniques as well as the means to “democratize” membrane filtration have been presented. Riverbank filtration is a “natural” filtration technique where drinking water is produced by placing wells on the banks of rivers. The riverbed/bank material and the underlying aquifer act as natural filters to remove pollutants from river water. Solar distillation can be a viable method of drinking water production for individual households to small communities without the input of external energy. Sustainability framework and technology transfer are discussed through transdisciplinary analysis.

The book is an overview of the diversity of anthropogenic aquifer recharge (AAR) techniques that use aquifers to store and treat water. It focusses on the processes and the hydrogeological and geochemical factors that affect their performance. This book is written from an applied perspective with a focus of taking advantage of global historical experiences, both positive and negative, as a guide to future implementation. Most AAR techniques are now mature technologies in that they have been employed for some time, their scientific background is well understood, and their initial operational challenges and associated solutions have been identified. However, opportunities exist for improved implementation and some recently employed and potential future innovations are presented. AAR which includes managed aquifer recharge (MAR) is a very important area of water resources management and there is no recent books that specifically and comprehensively addresses the subject.